Method for production of microfine colored particles and electrophotographic toner using the particles

A method for the production of microfine colored particles, characterized by subjecting a polymeric monomer suspended in a suspension medium to suspension polymerization in the presence of a coloring agent and/or a magnetic powder thereby forming microfine globular colored particles possessing an average particle diameter in the range of from 3 to 50 .mu.m, heat treating said microfine globular colored particles with water as a heating medium at a temperature in the range of from 50.degree. C. to 130.degree. C. thereby inducing fusion of said particles and giving rise to blocks of fused particles, and then disintegrating said blocks of particles to an average particle diameter substantially equal to the average particle diameter of said microfine globular colored particles existent prior to said fusion.

BACKGROUND OF THE INVENTION 
This application is a continuation-in-part of application Ser. No. 
07/734,787, filed Jul. 23, 1991 which in turn, is a continuation-in-part 
application of application 400,065, filed Aug. 29, 1989, now U.S. Pat. No. 
5,080,992 which was with said parent application hereof Ser. No. 
07/734,787. 
1. Field of the Invention 
This invention relates to a method for the production of microfine colored 
particles and an electrophotographic toner using the microfine colored 
particles obtained by this method. More particularly, this invention 
relates to a method for the production of microfine colored particles each 
having a coloring agent uniformly dispersed therein, enjoying a modified 
particle surface, and promising to find utility as a coloring agent in 
toners, coating materials, inks, molded articles of resin, etc. and an 
electrophotographic toner produced by using the microfine colored 
particles and enabled, when used as a toner in a printing device such as a 
laser printer or a liquid crystal printer, to form a clear image. 
This invention relates to a method for the recovery of microfine globular 
particles formed mainly of resin from a suspension. To be more specific, 
this invention relates to a method for efficient recovery from a 
suspension of microfine globular particles obtained by the suspension 
polymerization method, for example. 
2. Description of the Prior Art 
The electrophotographic method comprises forming an electric latent image 
on a photosensitive material which is made of such a photoconductive 
material as selenium, zinc oxide, or cadmium sulfide, developing the 
latent image with a powder developer, transferring the developed image to 
a paper, and fixing the image on the paper. 
Heretofore, the toner used for the development of the latent image in 
electrophotography has been generally produced by melting, mixing, and 
dispersing a coloring agent and other additives (such as a charge 
controlling agent, an offset preventing agent, and a lubricant) in a 
thermoplastic resin, solidifying the resultant dispersion, pulverizing the 
solid, classifying the produced particles, and collecting microfine 
colored particles of a desired particle diameter. 
The method which produces a toner in accordance with the pulverizing step 
as described above, however, entails various drawbacks. Firstly, it 
necessitates numerous steps including the step of producing a resin, the 
step of mixing this resin with a coloring agent and other additives, the 
step of pulverizing the resultant solid mixture, and the step of 
classifying the produced particles and collecting microfine colored 
particles of a desired particle diameter and, therefore, requires use of 
as many devices as these steps. The toner which is produced by this method 
is expensive as a necessary consequence. Particularly, the step of 
classification constitutes itself an indispensable requirement for the 
production of a toner having particle diameters in a range optimum for the 
formation of an image enjoying high clarity and suffering sparingly from 
the phenomenon of fogging. It nevertheless has a problem of deficiency in 
productional efficiency and yield. Secondly, in the step of mixing, it is 
extremely difficult for the coloring agent and other additives to be 
uniformly dispersed in the resin. The toner produced by this method, 
therefore, suffers from inferior dispersion of the coloring agent, the 
charge controlling agent, etc. and consequent lack of uniformity of 
triboelectric characteristic among component particles and inevitable 
decline of resolution. In the future, these problems will gain all the 
more in prominence as a growing impetus is given to the trend of these 
toners toward particle diameter reduction which forms an indispensable 
requirement for the formation of images of high quality. The existing 
pulverizing devices are limited in ability to allow particle diameter 
reduction for such toners. Even if they are capable of producing a toner 
of a reduced particle diameter, the toner produced thereby at all still 
suffers from heavy ununiformity of the amount of charging due to inferior 
dispersion of the coloring agent and the charge controlling agent. 
For the elimination of various drawbacks observed in the toner produced by 
the method of pulverization mentioned above, various methods for the 
production of a toner by the use of the emulsion polymerization technique 
or the suspension polymerization technique have been proposed (Japanese 
Patent Publications SHO 36(1961)-10,231, SHO 43(1968)-10,799, SHO 
47(1972)-518,305, SHO 51(1976)-14,895, etc.). These methods invariably 
resort to a procedure of synthesizing a toner containing a coloring 
substance in one step of subjecting to emulsion or suspension 
polymerization a polymerizable monomer incorporating therein the coloring 
substance such as carbon black and other additives. These methods are 
capable of mending the drawbacks of the conventional pulverizing method to 
a noticeable extent. Since they include absolutely no step of 
pulverization, they find no use for improvement of brittleness of the 
produced toner. Further, since the individual particles of the produced 
toner have a globular shape and excel in flowability, they enjoy 
uniformity of triboelectric characteristic. The method for the production 
of a toner by the technique of polymerization, however, has a problem of 
its own. Firstly, since such hydrophilic substances as a dispersant and a 
surfactant which are used in the process of polymerization are not 
completely removed in the step of washing and are suffered to persist in 
the toner particle surface, the charging property of the produced toner is 
susceptible of the influence of the environment. Secondly, since the toner 
particles produced by the technique of polymerization have a spheric shape 
and a very smooth surface, the toner deposited fast on the sensitive 
material is not easily removed and the sensitive material is consequently 
compelled to suffer from poor cleanability. Various methods aimed at 
solution of these problems have been proposed in Japanese Patent 
Application Disclosures SHO 61(1986)-255,354, SHO 53(1978)-17,736, SHO 
63(1988)-17,460, SHO 61(1986)-167,956, etc. These methods are 
impracticable because they bring about no fully satisfactory effects and 
lead to increases of cost. 
For the solution of problems of this sort, methods for the production of an 
electrophotographic toner possessing a desired particle diameter have been 
disclosed which generally comprise emulsifying, dispersing, and 
polymerizing a polymerizable monomer, a coloring agent, and/or a magnetic 
powder, and a polymerization initiator in the presence of an emulsifier 
thereby preparing a main resin component, solidifying the resultant 
polymerization solution at a temperature not exceeding the glass 
transition point of the main resin component, heating the particles 
resulting from the solidification at a temperature exceeding the glass 
transition point of the main resin component thereby effecting thorough 
dissolution of the particles, and classifying the resultant solid 
particles (Japanese Patent Application Disclosures SHO 61(1986)-167,955, 
SHO 61(1986)-167,956, SHO 61(1986)-167,957, and SHO 61(1986)-72,258). 
In these methods, however, since the polymerization is carried out mainly 
in the form of emulsion polymerization, the produced polymer particles 
acquire a particle diameter on the order of submicrons and the coloring 
agent such as carbon black is not included in the polymer particles but is 
left standing outside the polymer particles. Even if these microfine 
polymer particles are occluded in larger particles in the subsequent step 
of solidification or thermal fusion, they cannot be uniformly dispersed 
therein. As a result, the produced toner suffers from lack of uniform 
dispersion of the coloring agent and, when used as an electrophotographic 
toner, entails lack of uniform electric charging or causes a draft of 
toner, possibly followed by the phenomenon of fogging or the defilement of 
the drum surface. The polymer particles obtained by polymerization in 
these methods are so small that their particle diameters are required to 
be controlled as well as increased by having the polymer particles 
subjected to solidification in the step of solidification at a temperature 
not exceeding the glass transition point of the resin. The solidification 
necessitates use of an inorganic acid or an organic acid as a solidifying 
agent. This solidifying agent cannot be thoroughly removed from the toner 
no matter how thoroughly the toner may be washed. The residual solidifying 
agent has the problem of rendering the toner resistant to dependency on 
the environment and compelling a decline in the electric property of the 
toner. 
SUMMARY OF THE INVENTION 
An object of this invention, therefore, is to provide a novel method for 
the production of microfine colored particles and an electrophotographic 
toner using the microfine colored particles obtained by this method. A 
further object of this invention is to provide a method for the production 
of microfine colored particles each having a coloring agent uniformly 
dispersed therein and, at the same time, enjoying a modified particle 
surface. Another object of this invention is to provide a method for the 
production of microfine colored particles promising to find utility as a 
coloring agent for toners, coating materials, inks, molded articles of 
resin, etc. Still another object of this invention is to provide an 
electrophotographic toner which, when used as a toner for such a printer 
device as a laser printer or a liquid crystal printer, produces clear 
images. A further object of this invention is to provide a novel method 
for the recovery from a suspension of microfine globular particles formed 
mainly of resin. Yet another object of this invention is to provide a 
method for efficient recovery from a suspension of microfine globular 
particles obtained as by the suspension polymerization technique, for 
example. 
The present inventors have continued a diligent study with a view to 
overcoming the adverse state of affairs mentioned above, to find that 
microfine colored particles obtained by treating microfine globular 
colored particles resulting from suspension polymerization through a 
specific sequence of steps are perfectly free from all of the problems 
mentioned above and useful advantageously as a coloring agent for coating 
materials, inks, and molded articles of resin, let alone 
electrophotographic toners and that an electrophotographic toner using the 
microfine colored particles, when used in a printing device such as a 
laser printer or a liquid crystal printer, produces very clear images 
positively free from the problems inherent in the prior art mentioned 
above. The present invention has been perfected as a result. 
The various objects described above are accomplished by a method for the 
production of microfine colored particles characterized by suspending a 
polymerizable monomer in a suspension medium in the presence of a coloring 
agent and/or a magnetic powder, subjecting the resultant suspension to 
suspension polymerization, heat treating the resultant microfine globular 
colored particles having an average particle diameter in the range of from 
3 to 50 .mu.m with water as a heating medium at a temperature in the range 
of from 50.degree. to 130.degree. C. thereby converting the particles 
through fusion into blocks of particles, and disintegrating the blocks 
into particles of an average particle diameter substantially equal to that 
of the microfine globular colored particles existing prior to the fusion. 
In the method for the production of microfine colored particles according 
with the present invention, the heat treatment mentioned above can be 
carried out in the state in which the microfine globular colored particles 
resulting from suspension polymerization are present in the suspension 
medium which is water. Alternatively, this heat treatment may be performed 
on a cake of the microfine globular colored particles withdrawn from the 
suspension medium. 
In one preferred embodiment of this invention, the method for production of 
microfine colored particles comprises suspending a polymerizable monomer 
in a suspension medium in the presence of a coloring agent and/or a 
magnetic powder, subjecting the resultant suspension to suspension 
polymerization, heat treating the suspension of microfine globular colored 
particles having an average particle diameter in the range of from 3 to 50 
.mu.m at a temperature in the range of from 50.degree. to 98.degree. C. 
thereby effecting aging polymerization and, at the same time, converting 
the particles through fusion into blocks of particles, and disintegrating 
the blocks into particles having an average particle diameter 
substantially equal to that of the microfine globular colored particles 
existent prior to the fusion. 
In further preferred embodiment of this invention, the method for 
production of microfine colored particles comprises suspending a 
polymerizable monomer in a suspension medium in the presence of a coloring 
agent and/or a magnetic powder, polymerizing the resultant suspension and, 
after the conversion of the microfine globular colored particles having an 
average particle diameter in the range of from 3 to 50 .mu.m has passed 
90%, (1) adding water-insoluble microfine particles to the suspension, (2) 
heat treating the resultant mixture at a temperature in the range of from 
50.degree. to 98.degree. C., thereby effecting aging polymerization and, 
at the same time, converting the microfine globular colored particles 
through fusion into blocks of particles, and then disintegrating the 
blocks of particles into particles having an average particle diameter 
substantially equal to that of the microfine globular colored particles 
existent prior to the fusion. 
In yet another embodiment of the present invention, the method for 
production of microfine colored particles comprises suspending a 
polymerizable monomer in a suspension medium in the presence of a coloring 
agent and/or a magnetic powder, polymerizing the resultant suspension, 
separating from the suspension the resultant microfine globular colored 
particles having an average particle diameter in the range of from 3 to 50 
.mu.m, subjecting the cake consequently obtained to a heat treatment under 
the conditions of 50.degree. to 130.degree. C. in temperature and 70 to 
100% in relative humidity thereby converting the particles through fusion 
into blocks of particles, and disintegrating the blocks of particles into 
particles having an average particle diameter substantially equal to that 
of the microfine globular colored particles existent prior to the fusion. 
In a preferred embodiment of the present invention, the microfine colored 
particles are produced by suspending a polymerizable monomer in a 
suspension medium in the presence of a coloring agent and/or a magnetic 
powder, polymerizing the resultant suspension, separating from the 
suspension the resultant microfine globular colored particles having an 
average particle diameter in the range of from 3 to 50 .mu.m, subjecting 
the cake consequently obtained to a heat treatment with hot water at 
50.degree. to 130.degree. C. thereby converting the particles through 
fusion into blocks of particles, and then disintegrating the blocks into 
particles having an average particle diameter substantially equal to that 
of the microfine globular colored particles existent prior to the fusion. 
The present invention is further directed to an electrophotographic toner 
of which particles each contain the microfine colored particle obtained by 
the method of production described above. 
This invention is also directed to a method for the recovery of microfine 
suspended particles from a suspension medium, characterized by suspending 
a polymerizable monomer in a suspension medium, subjecting the resultant 
suspension to suspension polymerization, adding microfine water-insoluble 
particles to the suspension of resultant microfine globular particles, 
causing agglomeration of the microfine globular particles, and separating 
the microfine globular particles in the form of agglomerated lumps by 
filtration from the suspension medium. 
By the method of production according with the present invention, there can 
be produced microfine colored particles each of which enjoys uniformity of 
particle size, possesses a jogging particle surface, exhibits a marked 
decrease in the residual content of the surfactant and the dispersant 
remaining after use in the suspension polymerization, and has substantial 
freedom from variations of physical properties accompanied by a change in 
humidity. The microfine colored particles of the present invention, 
therefore, are usable advantageously as an electrophotographic toner 
capable of forming clear images and excellent in flowability and 
cleanability and also usable as a coloring agent or a modifying agent for 
coating materials, inks, and molded articles of resin. Particularly the 
electrophotographic toner of this invention which is produced by using the 
microfine colored particles described above is capable of forming images 
excellent in quality and free from the phenomenon of fogging at all times 
under environments of all sorts and, therefore, is usable in a wide 
variety of electrophotographic devices. Further, the method of the present 
invention for recovery of microfine globular particles from a suspension 
medium realizes and facilitates the solid-liquid separation by the use of 
an ordinary filtering device even when the microfine globular particles 
obtained by suspension polymerization happen to have a small particle 
diameter. This method, therefore, contributes to enhancing the 
productivity of the. aforementioned method in the production of the 
microfine colored particles of the nature described above.

DETAILED DESCRIPTION OF THE INVENTION 
Now, the present invention will be described in detail below with reference 
to embodiments thereof. 
In the method of the present invention for the production of microfine 
colored particles, first a polymerizable monomer is suspended in a 
suspension medium in the presence of a coloring agent and/or a magnetic 
powder and polymerizing the resultant suspension. The microfine globular 
colored particles obtained by the suspension polymerization have an 
average particle diameter in the range of from 3 to 50 .mu.m, preferably 
3.5 to 20 .mu.m. This range of the average particle diameter has an 
extremely important significance from the standpoint of producing the 
microfine colored particles of this invention through the step of heat 
treatment and the step of disintegration which will be described 
specifically hereinbelow. The polymer particles which are obtained by a 
polymerization technique other than the suspension polymerization such as, 
for example, the emulsion polymerization technique generally have an 
average particle diameter approximately in the neighborhood of 0.1 .mu.m. 
Microfine colored particles which are produced by heat treating these 
smaller polymer particles with water as a heating medium and 
disintegrating the resultant solid particles are conspicuously different 
in shape of particle and particle diameter distribution from the microfine 
colored particles obtained by the method of production according with the 
present invention. When the smaller microfine colored particles are used 
as a toner, it cannot produce images of fully satisfactory quality. 
This suspension polymerization is desired to be performed after regulation 
of particle diameter or to be continued simultaneously with regulation of 
particle diameter. Preferably, it is performed after regulation of 
particle diameter. The regulation of the particle diameter is executed, 
for example, by dispersing prescribed components in an aqueous medium and 
passing the resultant suspension at least once through a line mixer such 
as T. K. Homomixer (manufactured by Tokushu Kika Kogyo K.K.) or Ebara 
Milder (manufactured by Ebara Mfg. Co., Ltd.). 
The reaction of suspension polymerization is generally carried out at a 
temperature in the range of from 40.degree. to 130.degree. C., preferably 
from 50.degree. to 90.degree. C., for a period in the range of from 0.5 to 
30 hours, preferably from 2 to 10 hours. 
The polymerizable monomers which are effectively usable as a polymerizable 
monomer component for the suspension polymerization include styrene type 
monomers such as styrene, o-methyl styrene, m-methyl styrene, p-methyl 
styrene, alpha-methyl styrene, p-methoxy styrene, p-tertbutyl styrene, 
p-phenyl styrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; 
acrylic acid or methacrylic acid type monomers such as methyl acrylate, 
ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, 
stearyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl 
methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl 
methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl 
methacrylate, and stearyl methacrylate; and ethylene, propylene, butylene, 
vinyl chloride, vinyl acetate, and acrylonitrile, for example. These 
polymerizable monomers may be used either singly or in the form of a 
mixture of two or more members. 
By suspension polymerizing the polymerizable monomer described above and 
then heat treating the resultant microfine globular colored particles 
under the conditions to be described hereinbelow, the operational 
efficiency of the disintegration is improved. The operational efficiency 
of the disintegration is inferior when the fusion of particles proceeds 
excessively during the heat treatment. No sufficient effect of the 
treatment of particle surface is obtained when the fusion is insufficient. 
A cross-linking agent may be used during the suspension polymerization for 
the purpose of avoiding excessive fusion. 
The cross-linking agents which are effectively usable herein include 
aromatic divinyl compounds such as divinyl benzene, divinyl naphthalene, 
and derivatives thereof; diethylenically unsaturated carboxylic esters 
such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 
triethylene glycol dimethacrylate, trimethylol propane triacrylate, allyl 
methacrylate, t-butylaminoethyl methacrylate, tetraethylene glycol 
dimethacrylate, and 1,3-butane diol dimethacrylate; all divinyl compounds 
such as N,N-divinyl aniline, divinyl ether, divinyl sulfide, and divinyl 
sulfonic acid; and compounds possessing at least three vinyl groups, for 
example. 
Polybutadiene, polyisoprene, unsaturated polyesters, and polyolefin 
chlorosulfonide are also effectively usable. 
The coloring agent to be used for the production of microfine globular 
colored particles may be any of the dyes and pigments known to the art 
without reference to discrimination between organic and inorganic 
substances. The coloring agents which are effectively usable herein 
include carbon black, nigrosine dyes, aniline blue, calco-oil blue, chrome 
yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue 
chloride, phthalocyanine blue, malachite green oxalate, lamp black, oil 
black, azo oil black, and rose bengal, for example. Two or more of these 
coloring agents, when necessary, may be jointly used. 
The magnetic powder is made of a substance which possesses a magnetic 
property and may be colored. Where such magnetic powders are colored they 
may be used alone, as coloring agents, or in conjunction with coloring 
agents. The magnetic powders which are effectively usable herein include 
powders of ferromagnetic metals such as iron, cobalt, and nickel and 
powders of metallic compounds such as magnetite, hematite, and ferrite, 
for example. These magnetic powders may be used as coloring agents either 
independently or in combination with the coloring agent mentioned above. 
The coloring agent and/or the magnetic powder may be used in its unmodified 
form. When the coloring agent and/or the magnetic powder which has been 
given a surface treatment by a suitable method is used, the microfine 
colored particles to be produced have the coloring agent and/or the 
magnetic powder dispersed uniformly therein. This microfine colored 
particles are desirable because they produce images of high quality when 
they are used as a toner, for example. When carbon black is used as the 
coloring agent, for example, the carbon black graft polymer disclosed in 
Japanese Patent Unexamined Publications SHO 63(1988)-270,767 and SHO 
63(1988)-265,913 proves to be ideal. When a coloring agent other than 
carbon black is used, the surface-treated coloring agent produced by the 
method disclosed in Japanese Patent Unexamined Publication HEI 
1(1989)-118,573 proves to be ideal. These are associated herein by 
reference. 
Though the amount of the coloring agent and/or the magnetic powder to be 
incorporated in the microfine colored particles may be varied in a wide 
range to suit the kind of the coloring agent and/or the magnetic powder to 
be used or the purpose for which the produced microfine colored particles 
are used, it is generally desired to be in the range of from 1 to 200 
parts by weight, preferably from 1 to 100 parts by weight, based on 100 
parts by weight of the polymerizable monomer. 
For the production of the microfine globular colored particles by the use 
of the coloring agent and/or the magnetic powder, the method which 
comprises preparing a polymerizable monomer having the coloring agent 
and/or the magnetic powder dissolved or dispersed therein and suspension 
polymerizing the polymerizable monomer is generally adopted conveniently. 
At times, this production may be effected by the method which comprises 
preparing globular polymer particles by polymerization performed in the 
absence of the coloring agent and/or the magnetic powder and then causing 
the globular polymer particles to absorb the coloring agent and/or the 
magnetic powder by the use of a suitable solvent. 
The stabilizers which are effectively usable in the suspension 
polymerization include water-soluble macromolecules such as polyvinyl 
alcohol, starch, methyl cellulose, carboxymethyl cellulose, hydroxyethyl 
cellulose, sodium polyacrylate, and sodium polymethacrylate; surfactants 
such as anionic surfactants, cationic surfactants, amphoteric ionic 
surfactants, and nonionic surfactants; and barium sulfate, calcium 
sulfate, barium carbonate, magnesium carbonate, calcium phosphate, talc, 
clay, diatomaceous earth, and powdered metal oxides, for example. 
The anionic surfactants which are effectively usable herein include fatty 
acid salts such as sodium oleate and castor oil potash, alkyl sulfuric 
ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate, 
alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, alkyl 
naphthalene sulfonates, alkane sulfonates, dialkyl sulfosuccinates, alkyl 
phosphoric ester salts, naphthalene sulfonic acid-formalin condensate, 
polyoxyethylene alkylphenyl ether sulfuric ester salts, and 
polyoxyethylene alkyl sulfuric ester salts, for example. 
The nonionic surfactants which are effectively usable herein include 
polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, 
polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxy 
sorbitan fatty acid esters, polyoxyethylene alkyl amines, glycerin fatty 
acid esters, and oxyethylene-oxypropylene block polymers, for example. 
The cationic surfactants which are effectively usable herein include alkyl 
amine salts such as lauryl amine acetate and stearyl amine acetate and 
quaternary ammonium salts such as lauryl trimethyl ammonium chloride, for 
example. 
The amphoteric ionic surfactants usable effectively herein are represented 
by lauryl dimethyl amine oxide. 
The stabilizer ought to be used with the composition and the amount of use 
thereof properly adjusted so that the produced microfine globular colored 
particles may assume particle diameters in the range of from 3 to 50 
.mu.m, preferably from 3.5 to 20 .mu.m. When a water-soluble macromolecule 
is used as the stabilizer, for example, the amount of this stabilizer is 
desirably in the range of from 0.01 to 20% by weight, preferably 0.1 to 
10% by weight, based on the amount of the polymerizable monomer component. 
When a surfactant is adopted as the stabilizer, the amount of the 
stabilizer to be used is in the range of from 0.01 to 10% by weight, 
preferably 0.1 to 5% by weight, based on the amount of the polymerizable 
monomer component. 
As the polymerization initiator for use in the polymerization, any of the 
oil-soluble peroxide type and azo type initiators which are generally used 
for suspension polymerization can be adopted. The polymerization 
initiators which are effectively usable herein include peroxide type 
initiators such as benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, 
benzoyl orthochloroperoxide, benzoyl orthomethoxyperoxide, methylethyl 
ketone peroxide, diisopropyl peroxy dicarbonate, cumene hydroperoxide, 
cyclohexanone peroxide, t-butyl hydroperoxide, and diisopropyl benzene 
hydroperoxide, and 2,2'-azo-bis-isobutylonitrile, 
2,2'-azo-bis-(2,4-dimethyl valeronitrile), 2,2'-azo-bis-2,3-dimethyl 
butylonitrile, 2,2'-azo-bis-(2-methyl butylonitrile), 
2,2'-azo-bis-2,3,3-trimethyl butylonitrile, 2,2'-azo-bis-2-isopropyl 
butylonitrile, 1,1'-azo-bis-(cyclohexane-1-carbonitrile), 
2,2'-azo-bis-(4-methoxy-2,4-dimethyl valeronitrile), 2-(carbamoyl-azo) 
isobutylonitrile, 4,4'-azo-bis-4-cyanovaleic acid, and 
dimethyl-2,2'-azo-bis-isobutylate, for example. The polymerization 
initiator is desirably used in an amount in the range of from 0.01 to 20% 
by weight, preferably from 0.1 to 10% by weight, based on the amount of 
the polymerizable monomer. 
In the production of the microfine globular colored particles by the 
suspension polymerization of the polymerizable monomer component described 
above, the monomer component may incorporate therein other polymer such 
as, for example, a polyester and further incorporate therein a suitable 
amount of a known additive such as a chain transfer agent for the purpose 
of adjustment of polymerization degree. When the microfine colored 
particles of this invention are intended for use in an electrophotographic 
toner, it can be produced in a state occluding therein wax and a charge 
controlling agent by having these additives incorporated in advance in the 
polymerizable monomer during the production. The microfine globular 
colored particles thus produced are desired to be such that the average 
particle diameter is in the range of from 3 to 50 .mu.m, preferably from 
3.5 to 20 .mu.m and the particle diameter distribution expressed by the 
coefficient of variation of particle diameters is in the range of from 0 
to 80%, preferably 1 to 50%. The expression "coefficient of variation of 
particle diameter" as used herein means the percentage of the quotient of 
the standard deviation divided by the average particle diameter. 
In the method of production according with the present invention, the 
microfine globular colored particles obtained by suspension polymerization 
and having an average particle diameter in the range of from 3 to 50 .mu.m 
are converted into fusion blocks of particles by heat treating with water 
as a heating medium at a temperature in the range of from 50.degree. to 
130.degree. C. 
This heat treatment can be carried out in the state in which the microfine 
globular colored particles resulting from the suspension polymerization 
are present in water as a suspension medium. Otherwise, the heat treatment 
may be carried out on a cake of microfine globular colored particles which 
is removed from the suspension medium. A plurality of these treatments may 
be performed in a combined state. As concrete means for executing the heat 
treatment of the cake of microfine globular colored particles removed from 
the suspension medium, a method which comprises placing the cake on a 
suitable retaining member and pouring hot water of a temperature exceeding 
the aforementioned prescribed temperature in the form of shower onto the 
cake and a method which comprises retaining the cake at a prescribed 
temperature under a prescribed high humidity may be conceived, for 
example. This heat treatment may be alternatively carried out under normal 
pressure, a reduced pressure, or an increased pressure. 
This heat treatment is an extremely important and indispensable step for 
the modification of the surface of the microfine globular colored 
particles. If the temperature of the hot water used in this case is lower 
than 50.degree. C., the fusion of the microfine globular colored particles 
does not occur at all or it occurs only insufficiently, with the result 
that a conspicuous effect of surface modification will not be manifested. 
Conversely, if this temperature exceeds 130.degree. C., the fusion of 
microfine globular colored particles proceeds excessively to an extent 
such that the subsequent step of disintegration is carried out only with 
difficulty and the produced microfine colored particles have a very wide 
particle diameter distribution. 
Particularly in the first mode in which the heat treatment is carried out 
by heating the suspension of the microfine globular colored particles, the 
temperature at which the suspension is heated is desired to be in the 
range of from 50.degree. C. to 98.degree. C., preferably from 60.degree. 
C. to 95.degree. C. If this temperature exceeds 98.degree. C., the fusion 
proceeds unduly quickly and defies control in terms of time. If it exceeds 
100.degree. C., the fusion is required to be carried out under an 
increased pressure. 
Further in this first mode of heat treatment, the conversion of the 
microfine globular colored particles in the suspension polymerization 
solution is desired to be not less than 90% during the thermal fusion of 
the microfine globular colored particles. The method of the present 
invention could be executed if the conversion was 100%. Since the time 
required for the production of the suspended polymer solution increases 
and the temperature required for the heat treatment rises in accordance as 
the conversion increases, the heat treatment cannot be effectively carried 
out under normal pressure and must be performed under an increased 
pressure attainable by the use of an autoclave, for example. The method, 
therefore, is desired to be such as to allow survival of the unaltered 
monomer to some extent. From the commercial point of view, therefore, the 
conversion is desired to be in the range of from 90 to 99.9%, preferably 
from 95 to 99.9%. If the conversion is less than 90%, since the unaltered 
monomer plasticizes the microfine globular colored particles and the 
heating induces fusion of these particles accompanied by complete loss of 
boundary surface, the subsequent disintegration encounters difficulty in 
giving the produced particles the same average particle diameter as that 
of the microfine globular colored particles existent prior to the fusion. 
A mass of blocks of particles is obtained by heat treating the microfine 
globular colored particles in the suspension solution thereby effecting 
aging polymerization and further polymerization of the unaltered monomer 
and consequently inducing fusion of the microfine globular colored 
particles. 
In the second mode in which the heat treatment is performed on the cake of 
microfine colored particles separated from the suspension solution under 
high humidity, the temperature of the high-humidity gas to be used for the 
heat treatment is desired to be in the range of from 70.degree. C. to 
100.degree. C. and the relative humidity of the atmosphere enveloping the 
site of the heat treatment is desired to be in the range of from 70 to 
100%, preferably from 80 to 100%. If the relative humidity is less than 
70%, since the water in the cake is vaporized, the fusion proceeds 
ununiformly or it does not proceed as quickly as required. The 
high-humidity heat treatment performed as described above induces aging 
polymerization and further polymerization of the unaltered monomer and, at 
the same time, effects fusion of the microfine globular colored particles, 
to give rise to the mass of blocks of particles. This high-humidity heat 
treatment is generally carried out for a period in the range of from 2 to 
90 minutes, preferably from 5 to 60 minutes. 
In the third mode in which the heat treatment is executed by pouring hot 
water on the cake of microfine colored particles separated from the 
suspension solution, the hot water to be used for this heat treatment is 
desired to have a temperature in the range of from 70.degree. C. to 
100.degree. C. The hot water heat treatment performed as described above 
induces aging polymerization and further polymerization of the unaltered 
monomer and, at the same time, effects fusion of the microfine globular 
colored particles to give rise to the mass of blocks of particles. The hot 
water heat treatment is generally carried out for a period in the range of 
from 2 to 90 minutes, preferably from 5 to 60 minutes. The hot water heat 
treatment may be carried out in a solid-liquid separating device such as, 
for example, a filter or a centrifuge which has been used in the 
withdrawal of the microfine globular colored particles from the suspension 
solution. In this case, the particles under treatment may be 
simultaneously washed with hot water without obstructing the treatment. 
The microfine globular colored particles are mutually fused by the heat 
treatment performed as described above. The state of this fusion may be 
arbitrarily controlled by regulating the effect of treatment as desired. 
In order for the subsequent step of disintegration to form microfine 
colored particles having a uniform particle diameter distribution and 
possessing properties excellent for an electrophotographic toner, the 
ideal state of fusion is such that the boundary surface of the particles 
does not wholly disappear but remains at least partially. Further, in the 
first mode in which the heat treatment is effected by heating the 
suspension solution of the microfine globular colored particles, it is 
permissible to add a flocculating agent, when necessary, to the suspension 
solution prior to the heat treatment. This addition of the flocculating 
agent promotes cohesion or sedimentation of the microfine globular colored 
particles and facilitates the mutual fusion of these particles by the heat 
treatment. Likewise in the second and third modes in which the heat 
treatment is performed on the cake of microfine globular colored particles 
withdrawn from the suspension medium, it is beneficial for the withdrawal 
of the microfine globular colored particles from the suspension medium to 
add a flocculating agent to the suspension medium and induce cohesion or 
sedimentation of the microfine globular colored particles. This is because 
the microfine globular colored particles contemplated by this invention 
have an extremely small average particle diameter falling in the range of 
from 3 to 50 .mu.m as described above and, therefore, the withdrawal of 
these particles in the unmodified form from the suspension solution is 
extremely difficult and the withdrawal, if carried out at all, 
necessitates consumption of a huge amount of energy or use of a special 
device. The cohesion or sedimentation of the microfine globular colored 
particles in the suspension solution proves to be desirable also from the 
standpoint of the ease with which the bulk density of the blocks of 
particles obtained by the fusion is controlled or the ease with which the 
cake resulting from the filtration is handled. 
The flocculating agent which is used for this purpose may be selected from 
among the known flocculating agents, which include inorganic acids such as 
hydrochloric acid, organic acids such as oxalic acid, and water-soluble 
metal salts formed between these acids and alkaline earth metals and 
aluminum, for example. The use of these known flocculating agents require 
due attention because they have the possibility of affecting the 
performance of the produced microfine colored particles when they are used 
as an electrophotographic toner. The present inventors have found that a 
bad solvent for the microfine globular colored particles can be used as a 
sedimenting agent during the isolation or fractionation of a 
macromolecular substance and further that the microfine colored particles 
produced by the use of this solvent are free from the drawbacks observed 
in the product using a flocculating agent. The bad solvents which are 
effectively usable for this purpose include hydrocarbons such as hexane, 
heptane, octane, and petroleum ether and lower alcohols such as methanol 
and ethanol, for example. The expression "bad solvent for the microfine 
globular colored particles" as used herein means a solvent which is 
incapable of dissolving or dispersing the resin forming the microfine 
globular colored particles. Of course, the bad solvent or sedimenting 
agent of the nature described above can be used in combination with the 
known flocculating agent unless the combined use causes an inconvenience. 
The present inventors have also found that when microfine water-insoluble 
particles are added to the suspension solution of the microfine globular 
colored particles, the same stable flocculation is effected to form blocks 
of particles of a desirable size as when the known flucculating agent is 
used, the operation of fusion can be stably performed, and the produced 
microfine colored particles are free from the drawbacks observed in the 
product obtained when a flocculating agent is used. The microfine 
water-insoluble particles to be used in the present invention are intended 
to keep the cohesion or fusion of the microfine globular colored particles 
in the optimum condition, notably enhance the disintegrability of the 
blocks of particles in the subsequent step and, at the same time, enable 
the microfine colored particles resulting from the disintegration to 
manifest high physical properties. The particle diameter of the microfine 
water-insoluble particles, therefore, must be smaller than that of the 
microfine globular colored particles. To be specific, it is desired to be 
less than one half of the particle diameter of the microfine globular 
colored particles. 
In a preferred embodiment of the present invention, therefore, the addition 
of such microfine water-insoluble particles to the suspension solution of 
the microfine globular colored particles is carried out prior to the step 
of thermal fusion of the microfine globular colored particles or the step 
of recovery of the microfine globular colored particles from the 
suspension solution. 
In one of the most preferred embodiments of the present invention, for 
example, there is adopted a procedure which comprises suspending a 
polymerizable monomer in a suspension medium in the presence of a coloring 
agent and/or a magnetic powder, polymerizing the resultant suspension and, 
after the conversion of the resultant microfine globular colored particles 
having an average particle diameter in the range of from 3 to 50 .mu.m has 
increased beyond 90%, (1) adding microfine water-insoluble particles to 
the suspension solution and then (2) heat treating the resultant mixture 
at a temperature in the range of from 50.degree. C. to 98.degree. C. 
thereby effecting aging polymerization and, at the same time, inducing 
fusion of the microfine globular colored particles and consequent 
conversion thereof into blocks of particles, and subsequently 
disintegrating the blocks of particles to an average particle diameter 
substantially equaling that of the microfine globular colored particles 
existent prior to the fusion. 
Now, the microfine water-insoluble particles which are used as one kind of 
flocculating agent in the present invention will be described specifically 
below. Various kinds of organic powders and inorganic powders can be used 
as the microfine water-insoluble particles. 
The organic powders which are effectively usable herein include 
cross-linked and non-cross-linked polymer powders, organic pigments, 
charge controlling agents, and waxes, for example. The cross-linked and 
non-cross-linked resin powders include styrene type resin powders, acrylic 
type resin powders, methacrylic type resin powders, polyethylene type 
resin powders, polypropylene type resin powders, silicone type resin 
powders, polyester type resin powders, polyurethane type resin powders, 
polyamide type resin powders, epoxy type resin powders, polyvinyl butyral 
type resin powders, rosin type resin powders, terpene type resin powders, 
phenol type resin powders, melamine type resin powders, and guanamine type 
resin powders, for example. The organic pigments which are effectively 
usable herein include yellow pigments such as navel yellow, naphthol 
yellow S, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR, 
quinoline yellow lake, permanent yellow NCG, and tartrazine lake, orange 
pigments such as molybdenum orange, permanent orange RK, benzidine orange 
G, and indanthrene brilliant orange GK, red pigments such as permanent red 
4R, resor red, pyrazolone, red 4R, watching red calcium salt, lake red D, 
brilliant carmine 6B, eosin lake, rhodamine lake B, azaline lake, and 
brilliant carmine B, purple pigments such as fast violet B and methyl 
violet lake, blue pigments such as alkali blue lake, victoria blue lake, 
phthalocyanine blue, nonmetallic phthalocyanine blue, partial chloride of 
phthalocyanine blue, fast sky blue, and indans blue BC, and green pigments 
such as pigment green B, malachite green lake, and fanal yellow green G, 
for example. The charge controlling agents which are effectively usable 
herein include powders of such substances as nigrosine, monoazo dyes, 
zinc, hexadecyl succinate, alkyl esters and alkyl amides of naphthoeic 
acid, nitrohumic acid, N,N-tetramethyl diamine benzophenone, 
N,N-tetramethyl benzidine, triazine, and metal complexes of salicylic acid 
which are called electrification controlling agents in the field of 
electrophotography. The waxes which are effectively usable herein include 
powders of polymers having a ring softening point in the range of from 
80.degree. C. to 180.degree. C., high-melting paraffin waxes having a 
melting point in the range of from 70.degree. C. to 60.degree. C., fatty 
acid esters and partially saponified derivatives thereof, higher fatty 
acids, metal salts of fatty acids, and higher alcohols, for example. 
The inorganic powders which are effectively usable herein include microfine 
particles or granules of alumina, titanium dioxide, barium titanate, 
magnesium titanate, calcium titanate, strontium titanate, zinc oxide, 
silica sand, clay, mica, tabular spar, diatomaceous earth, various 
inorganic oxide pigments, chromium oxide, cerium oxide, iron red, antimony 
trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium 
carbonate, calcium carbonate, silica, silicon carbide, silicon nitride, 
boron carbide, tungsten carbide, titanium carbide, and carbon black, for 
example. 
Of the water-insoluble powders cited above, those which have a 
hydrophobicity index (Mw : methanol wettability) of at least 5 prove to be 
particularly desirable because of their ability to impart ideal 
moistureproofness to the microfine globular particles to be obtained in 
consequence of disintegration. They are also beneficial in terms of the 
stability of charging which is manifested when the microfine globular 
particles are used as an electrophotographic toner. The water-insoluble 
powders which are particularly desirable as described above include 
various inorganic oxides such as silica, titanium, and zirconia which have 
undergone a treatment for impartation of hydrophobicity and 
electroconductive species of carbon black such as Ketjen black, acetylene 
black, and furnace black, for example. 
The term "hydrophobicity index" as used herein refers to the numerical 
value which is obtained by the following procedure. 
(1) In a beaker having an inner volume of 200 ml, 0.2 g of a given sample 
is placed and diluted with 50 ml of purified water. 
(2) The aqueous solution of the sample is kept stirred with a magnetic 
stirrer and methanol is added to the stirred solution under the surface. 
(3) The point at which the visible sign of the sample ceases to exist on 
the surface of the stirred solution is taken as the end point of the test. 
(4) The degree of hydrophobicity of the sample is calculated in accordance 
with the following formula using the amount of methanol consumed in the 
test. 
Hydrophobicity index (%)={x/(50+x)}.times.100 
wherein x stands for the amount of methanol used (ml). 
In consideration of the charging stability of the toner of a small particle 
diameter necessary for realizing the production of images of high 
resolution, the microfine water-insoluble particles to be selected for use 
herein are desired to possess electroconductivity. The microfine 
electroconductive water-insoluble particles which are effectively usable 
herein include powders of electroconductive carbon black, titanium oxide 
and tin oxide doped with antimony oxide, electroconductive zinc oxide, and 
titanium black, for example. 
To be used effectively for the purpose just mentioned, the microfine 
water-insoluble particles are desired to have particle diameters in the 
range of from 0.001 to 10 .mu.m, preferably from 0.005 to 5 .mu.m. If the 
microfine water-insoluble particles have particle diameters not exceeding 
0.001 .mu.m, there arises the possibility that the effect of the addition 
of these particles, i.e. the notable improvement in the property of 
flocculation, the disintegrability, the flowability, cleanability, etc. to 
be manifested by the particles when they are used as an 
electrophotographic toner, will be no longer manifested. Conversely, if 
the microfine water-insoluble particles have particle diameters exceeding 
10 .mu.m, there ensues the possibility that the effect of the addition of 
these particles will be unduly low and the improvement in resolution of 
images to be attained when the particles are used as an 
electrophotographic toner will not be manifested. The amount of these 
microfine water-insoluble particles to be added may be selected in a wide 
range, depending on the kind and particle diameter of the microfine 
water-insoluble particles to be used. If this amount is unduly small, the 
effect of the addition of these particles is manifested only with 
difficulty. If the amount is unduly large, the possibility arises that the 
particles, when used as an electrophotographic toner, will exert adverse 
effects on charging property and environmental stability. The amount of 
addition, therefore, is desired to be in the range of from 0.01 to 100 
parts by weight, preferably from 0.1 to 50 parts by weight, based on 100 
parts by weight of the polymerizable monomer component. The various 
species of microfine water-insoluble particles cited above may be used 
either singly or jointly in the form of a mixture of two or more members. 
It goes without saying that even when the microfine water-insoluble 
particles are used, the known flocculating agent or the bad solvent for 
microfine globular colored particles which is mentioned above may be 
simultaneously used unless the combined use brings about an inconvenience. 
Optionally, a proper organic solvent may be additionally used for the 
purpose of promoting the fusion. 
The cohesion or sedimentation of the microfine globular colored particles 
caused by the addition of the microfine water-insoluble particles of the 
kind described above to an aqueous suspension solution is initiated by 
making this addition to the suspension solution of the microfine globular 
particles and allowing the resultant mixture to stand for a prescribed 
period optionally in a stirred state without specifically requiring 
application of heat. In the method for production of the microfine colored 
particles of the present invention, application of heat within a 
prescribed range presents no problem of any sort because the microfine 
globular colored particles resulting from the suspension polymerization 
are brought into a mutually fused state, specifically the state in which 
these particles are mutually fused without complete loss of their boundary 
surface. To be specific, when the heat treatment for the fusion of 
microfine globular colored particles is carried out by heating the 
suspension of the microfine globular colored particles as in the first 
mode described above, the cohesion to fusion of the microfine globular 
colored particles can be continuously brought about by performing the 
application of heat at a temperature in the range of from 50.degree. C. to 
130.degree. C. subsequent to the addition of the microfine water-insoluble 
particles. When the heat treatment for fusion of microfine globular 
colored particles is carried out on the cake of microfine globular colored 
particles withdrawn from the suspension medium as in the second or third 
mode described above, the state of fusion can be produced to some extent 
in the aggregate withdrawn in the form of a cake from the suspension 
solution by performing the application of heat at or below a temperature 
in the range of from 50.degree. C. to 130.degree. C. for a brief period 
during the treatment of cohesion. 
In the case of the first mode described above in which the heat treatment 
for the fusion of the microfine globular colored particles is effected by 
heating the suspension solution of the microfine globular colored 
particles, the blocks of particles resulting from the fusion of the 
microfine globular colored particles are obtained from the suspension 
solution by the use of an ordinary solid-liquid separating device 
utilizing the principle of suction filtration, pressure filtration, or 
centrifugal filtration. The state of fusion to be produced in the blocks 
of particles is desired to be such that the product of the fusion acquires 
a bulk density in the range of from 0.1 to 0.9 g/cm.sup.3, preferably from 
0.2 to 0.7 g/cm.sup.3. Though the blocks of particles are not limited in 
shape or size, they are desired to give rise to particles having an 
average size in the range of from 20 to 10,000 .mu.m, preferably from 30 
to 1,000 .mu.m, in consideration of the conveniences of the operations of 
filtration, drying, and disintegration which follow the treatment for 
thermal fusion. If the size is less than 20 .mu.m, the withdrawal of 
particles entails consumption of a very large volume of energy or 
necessitates use of a special device. If this size exceeds 10,000 .mu.m, 
the disintegration calls for a huge energy. The blocks of particles 
obtained as described above are then forwarded to the step of 
disintegration via the step of drying. 
In the second and third modes described above in which the heat treatment 
for the sake of fusion of the microfine globular colored particles is 
performed on the cake of microfine globular colored particles withdrawn 
from the suspension medium, the microfine globular colored particles are 
desired to be converted by mutual cohesion into an aggregate of microfine 
particles in preparation for the solid-liquid separation of the microfine 
globular colored particles from the suspension medium so as to facilitate 
this separation by the use of an ordinary solid-liquid separating device. 
The aggregate of microfine particles is desired to have a bulk density in 
the range of from 0.05 to 0.9 g/cm.sup.3, preferably from 0.1 to 0.7 
g/cm.sup.3. Though the aggregate of microfine particles is not limited in 
shape and size, it is desired to be such as to give rise to particles of 
an average size in the range of from 20 to 10,000 .mu.m, preferably from 
30 to 1,000 .mu.m, in consideration of the conveniences of the operation 
of solid-liquid separation and the operations of drying and disintegration 
following the heat treatment. In these modes, the heat treatment described 
above is performed on the cake of microfine globular colored particles 
withdrawn as described above and, as a result, the blocks of particles 
resulting from fusion of the microfine globular colored particles are 
obtained. The state of fusion to be obtained is desired to be such that 
the blocks of particles acquire a bulk density in the range of from 0.1 to 
0.9 g/cm.sup.3, preferably 0.2 to 0.7 g/cm.sup.3. The blocks of particles 
are then forwarded, in much the same manner as in the first mode described 
above, to the step of disintegration through the step of drying. 
At the step of disintegration, the blocks of particles in a dry state are 
disintegrated to an average particle diameter substantially equal to that 
of the microfine globular colored particles existent prior to the fusion. 
The disintegration can be attained by the use of any of pulverizing 
devices heretofore employed for commercial production of particles and 
granules, for example. 
In an ideal mode, the disintegration to an average particle diameter 
substantially equal to that of the microfine globular colored particles 
existent prior to the fusion as referred to herein resides in causing the 
individual particles of the blocks of particles resulting from the fusion 
of microfine globular colored particles performed to an extent short of 
inducing complete loss of the boundary surface thereof as clearly shown in 
a scanning electron micrograph (60 magnifications) of FIG. 1 to be 
disintegrated into microfine globular colored particles existent prior to 
the fusion as units and consequently reverting the individual particles of 
the blocks to the state in which the microfine globular colored particles 
existent prior to the disintegration have been merely deformed. It is 
actually difficult, however, to control uniformly the state of fusion of 
the boundary surface. As shown clearly in a scanning electron micrograph 
(1,500 magnifications) of FIG. 2, the microfine colored particles to be 
produced are generally obtained in the form of a mixture of microfine 
particles which is produced when the microfine globular colored particles 
prior to the fusion and disintegration are deformed and, at the same time, 
partly chipped and the resultant chippings are caused to adhere to the 
deformed particles. Even when a set of the microfine colored particles is 
a mixture of this description, it is by no means inferior in quality to 
the microfine colored particles in the ideal form so long as the average 
particle diameter of the microfine globular colored particles of this 
mixture is substantial equal to that of the microfine globular colored 
particles prior to the fusion and disintegration. In this case, when the 
average particle diameter of the microfine colored particles has a rate of 
change generally within 20%, desirably within 10%, and more desirably 
within 5%, of the average particle diameter of the microfine globular 
colored particles, the average particle diameter of the microfine colored 
particles and that of the microfine globular colored particles may well be 
regarded as substantially identical. 
The microfine colored particles produced as described above are such that 
the particle diameter and the particle diameter distribution thereof have 
been controlled as desired. Ideally, however, the particle diameter is in 
the range of from 3 to 50 .mu.m, preferably from 3.5 to 20 .mu.m, and the 
average particle diameter distribution is such that the coefficient of 
variation of particle diameter is in the range of from 0 to 80%, 
preferably 0 to 50%. The term "coefficient of variation of particle 
diameter" as used herein means the percentage of the quotient of the 
standard deviation divided by the average particle diameter. Although the 
microfine colored particles are not specifically limited in shape, they 
may be either particles which are spheres macroscopically and yet have a 
finely jogging surface or nonspheric particles. 
The electrophotographic toner according with the present invention uses the 
microfine colored particles mentioned above. In order for this toner to 
possess a proper charging property, the average particle diameter is 
ideally in the range of from 3.5 to 20 .mu.m, preferably from 4 to 15 
.mu.m. The microfine colored particles may be used in their unmodified 
forms as an electrophotographic toner. 
Such additives as a charge controlling agent for the adjustment of charging 
and a fluidifying agent which are normally used in ordinary toners may be 
properly incorporated in the microfine colored particles of the present 
invention. 
The method for effecting the incorporation of a charge controlling agent is 
not particularly restricted. Any of the known methods available for the 
purpose of this incorporation may be adopted. For example, a method which 
comprises having the charge controlling agent incorporated in the 
polymerizable monomer in advance of the polymerization of the 
polymerizable monomer having a coloring agent dispersed therein and a 
method which comprises causing the charge controlling agent to be 
deposited fast on the surface of the microfine colored particles by 
aftertreating the microfine colored particles with the charge controlling 
agent may be properly adopted. 
In several preferred embodiments of the present invention, the cohesion or 
sedimentation of the microfine globular colored particles in the process 
of production is promoted and the solid-liquid separation of the microfine 
globular colored particles from the suspension medium is facilitated by 
adding microfine water-insoluble particles of the kind described above to 
the suspension of the microfine globular colored particles. This technical 
idea need not be limited to the method for the production of the microfine 
colored particles contemplated by this invention but may be extensively 
applied to the method for recovery of the microfine globular particles 
produced by suspension polymerization from the suspension medium and to 
the method for recovery of microfine particles by solid-liquid separation 
from a varying dispersion system having fine particles mainly of resin 
dispersed in an aqueous suspension solution such as, for example, a 
suspension obtained by heating and melting a resin component in an aqueous 
dispersion medium. 
This is because the cohesion or sedimentation which is induced after the 
addition of the microfine water-insoluble particles without application of 
heat at a particularly high temperature causes the microfine globular 
particles in the resultant blocks of particles to be fused by point 
contact or slight surface contact across their boundary surface and, as a 
result, the microfine particles which are obtained by separating the 
blocks of particles from the suspension solution by the use of an ordinary 
solid-liquid separating device mentioned above and drying and 
disintegrating the separated blocks of particles substantially retain the 
globular shape of the microfine particles obtained by suspension 
polymerization and show no sign of any deterioration of quality like the 
microfine particles produced by using a known flocculating agent. It is 
further because the disintegration which is effected by the use of a 
pulverizing device of relatively simple mechanism and small energy 
consumption is capable of converting the blocks of particles into 
particles of an average particle diameter substantially equaling the 
average particle diameter of the microfine globular particles existent 
prior to the cohesion. Of course, the treatment which follows the 
solid-liquid separation may be performed by any desired method. For 
example, the heat treatment to be performed for the purpose of modifying 
the surface property of microfine particles in the process of production 
of the microfine globular colored particles mentioned above may be 
adopted. The technique of recovery of microfine particles from the 
suspension solution by the use of the aforementioned microfine 
water-insoluble particles as a flocculating agent is believed to be 
particularly useful for the production of microfine globular particles 
having an average particle diameter in the range of from 1 to 100 .mu.m, 
especially from 1 to 50 .mu.m, and rendering difficult the separation 
thereof by the ordinary method of centrifugal sedimentation or for the 
production of microfine globular particles for use in an 
electrophotographic toner for which the deterioration of moistureproofness 
by the use of a known flocculating agent presents a particularly serious 
problem. 
In the recovery method of present invention, it is not necessary to heat 
the suspension after the addition of the microfine water-insoluble 
particles in order to induce the cohesion or sedimentation of the 
microfine particles in the suspension solution. Considering the operations 
efficiency, however, a heat treatment to a temperature exceeding the Tg of 
the polymer forming said microfine globular particles may be permissible 
unless the heat treatment causes excessive fusion of the microfine 
globular particles. 
EXAMPLE 
Now, the present invention will be described in detail below with reference 
to working examples, which are cited purely for the illustration of this 
invention and are not meant to be limitative in any sense of this 
invention. Wherever the term "parts" is mentioned in the following working 
examples and controls, it shall be construed invariably as "parts by 
weight" unless otherwise specified. 
Example 1 
In a reaction kettle provided with a stirrer, an inert gas inlet tube, a 
reflux cooling tube, and a thermometer, 2,000 parts of deionized water 
having 1 part of polyvinyl alcohol dissolved therein was placed. In this 
water, a mixture prepared in advance by dissolving 80 parts of benzoyl 
peroxide in a polymerizable monomer consisting of 585 parts of styrene, 
390 parts of butyl methacrylate, and 25 parts of glycidyl methacrylate was 
stirred at a high speed to form a homogeneous suspension. Then, the 
suspension was exposed to the blow of nitrogen gas and, at the same time, 
heated to 80.degree. C., stirred continuously at this temperature for five 
hours to undergo polymerization, and then deprived of water, to obtain a 
polymer having an epoxy group as a reactive group. 
By the use of a pressure kneader, 400 parts of the polymer having the epoxy 
group as a reactive group, 150 parts of carbon black (produced by 
Mitsubishi Chemical Industry Co., Ltd. and marketed under trademark 
designation of "Carbon Black MA-100R"), and 50 parts of a charge 
controlling agent (produced by Hodogaya Chemical Industry Co., Ltd. and 
marketed under trademark designation of "Aizen Spilon Black RH") were 
kneaded and caused to react under the conditions of 160.degree. C. and 100 
rpm. The resultant reaction mixture was cooled and pulverized, to produce 
a carbon black graft polymer as a coloring agent. 
In the same reaction kettle that was used above, 8,970 parts of deionized 
water having dissolved therein 5 parts of sodium dodecylbenzenesulfonate 
was placed. In this water, a mixture prepared in advance by combining 500 
parts of the aforementioned carbon black graft polymer as a coloring 
agent, 30 parts of azo-bis-isobutylonitrile, and 30 parts of 
2,2'-azo-bis-(2,4-dimethylvaleronitrile) with a polymerizable monomer 
component consisting of 800 parts of styrene, 200 parts of n-butyl 
acrylate, and 0.03 part of divinyl benzene was stirred by the use of a 
mixing device (produced by Tokushu Kika Kogyo K.K. and marketed under 
trademark designation of "T. K. Homomixer") at 8,000 rpm for five minutes, 
to form a homogeneous suspension. 
Then, the suspension was exposed to the blow of nitrogen gas and heated to 
65.degree. C., stirred continuously at this temperature for five hours to 
undergo suspension polymerization, and further heated at 75.degree. C. for 
one hour to afford a suspension (1) of microfine globular colored 
particles having a conversion of 95.0%, an average particle diameter of 
5.82 .mu.m, and a coefficient of variation of particle diameter of 20.5%. 
When the suspension (1) of the microfine globular colored particles kept 
at 75.degree. C. and 2,095 parts of methanol added thereto were heated for 
one hour, blocks having the particles mutually fused were obtained. The 
blocks were separated by filtration and dried by the use of a hot air 
drier at 50.degree. C. for 10 hours, to afford 1,500 parts of blocks 
having the individual particles fused in a state retaining their boundary 
surface thereof partially, possessing a bulk density of 0.20 g/cm.sup.3, 
and assuming the appearance of a cake of millet seeds glued with thick 
malt jelly. These blocks were fed at a rate of 15 kg/hr to an ultrasonic 
jet granulating device (produced by Nippon Pneumatic Kogyo K.K. and 
marketed under product code of "IDS2 Type") and disintegrated therein, to 
afford microfine colored particles (1). 
The microfine colored particles (1), by measurement with a Coulter Counter 
(aperture 100 .mu.m), were found to have an average particle diameter of 
5.67 .mu.m and a coefficient of variation of particle diameter of 18.7%. 
The microfine colored particles (1) were used in their unmodified forms as 
an electrophotographic toner (1) to produce images with an electrostatic 
copier (produced by Ricoh Company, Ltd. and marketed under product code of 
"Type -4060"). The results are shown in Table 1. 
Example 2 
In the same reaction kettle as used in Example 1, 8,970 parts of deionized 
water having dissolved therein 30 parts of polyvinyl alcohol (produced by 
Kuraray Company, Ltd. and marketed under product code of "PVA 205") was 
placed. In this water, a mixture prepared in advance by combining 50 parts 
of Brilliant Carmine 6B (produced by Noma Kagaku K.K.) as a coloring 
agent, 30 parts of azo-bis-isobutylonitrile, and 30 parts of 
2,2'-azo-bis-(2,4-dimethyl valeronitrile with a polymerizable monomer 
component consisting of 800 parts of styrene and 200 parts of n-butyl 
acrylate was stirred with a mixing device (produced by Tokushu Kiko Kogyo 
K.K. and marketed under trademark designation of "T. K. Homomixer") at 
6,000 rpm for five minutes, to form a homogeneous suspension. 
Then, the suspension was exposed to the blow of nitrogen gas and heated to 
65.degree. C. and stirred continuously at this temperature for five hours 
to undergo suspension polymerization and thereafter heated at 75.degree. 
C. for one hour, to afford a suspension (2) of microfine globular colored 
particles having a conversion of 98.0%, an average particle diameter of 
6.42 .mu.m, and a coefficient of variation of particle diameter of 21.3%. 
When the suspension (2) of the microfine globular colored particles kept 
at 75.degree. C. and 13 parts of an aqueous-paste charge controlling agent 
containing 35% of principal component (produced by Orient Kagaku Kogyo 
K.K. and marketed under trademark designation of "Bontron S-34") added 
thereto were heat treated at 95.degree. C. for one hour, to afford blocks 
having the individual particles mutually fused. The blocks were separated 
by filtration and dried by the use of a reduced-pressure drier at 
50.degree. C. for eight hours, to give rise to 1,110 parts of blocks 
having the individual particles fused in a state retaining the boundary 
surface thereof partially, possessing a bulk density of 0.28 g/cm.sup.3, 
and assuming the appearance of a cake of millet seeds glued with thick 
malt jelly. The blocks were fed at a rate of 12 kg/hr to an ultrasonic jet 
pulverizer (produced by Nippon Pneumatic Kogyo K.K. and marketed under 
product code of "IDS 2 Type") and disintegrated therein, to produce 
microfine colored particles (2). 
The microfine colored particles (2), by measurement with a Coulter Counter 
(aperture 100 .mu.m), were found to have an average particle diameter of 
6.15 .mu.m and a coefficient of variation of particle diameter of 23.0%. 
The microfine colored particles (2) were used in their unmodified form as 
an electrophotographic toner (2) to produce images with an electrostatic 
copier (produced by Ricoh Company, Ltd. and marketed under product code of 
"Type 4060"). The results are shown in Table 1. 
Example 3 
A polymer-treated magnetic material was obtained by kneading 200 parts of 
the polymer possessing an epoxy group as a reactive group obtained by 
following the procedure of Example 1 and 400 parts of a powdery magnetic 
material (produced by Titan Kogyo K.K. and marketed under trademark 
designation of "Mapico BL-200") by the use of a pressure kneader under the 
conditions of 160.degree. C. and 100 rpm, and then cooling and pulverizing 
the resultant blend. 
In the same reaction kettle as used in Example 1, 8,970 parts of deionized 
water having dissolved therein 5 parts of sodium dodecylbenzenesulfonate 
as an anionic surfactant was placed. In this water, a mixture prepared in 
advance by combining 700 parts of the aforementioned polymer-treated 
magnetic material, 30 parts of azo-bis-isobutylonitrile, and 30 parts of 
2,2'-azo-bis-(2,4-dimethyl valeronitrile) with a polymerizable monomer 
component consisting of 800 parts of styrene, 200 parts of n-butyl 
acrylate, and 0.1 part of divinyl benzene was stirred by the use of a 
mixing device (produced by Tokushu Kika Kogyo K.K. and marketed under 
trademark designation of "T. K. Homomixer") at 8,000 rpm for five minutes, 
to form a homogeneous suspension. 
Then, the suspension was exposed to the blow of nitrogen gas and heated to 
65.degree. C., stirred continuously at this temperature for five hours to 
undergo suspension polymerization, and heated further at 75.degree. C. for 
one hour, to afford a suspension (3) of microfine globular colored 
particles having a conversion of 98.0%, an average particle diameter of 
5.43 .mu.m, and a coefficient of variation of particle diameter of 22.5%. 
The suspension (3) of the microfine globular colored particles kept at 
75.degree. C. and 41 parts of an aqueous-paste charge controlling agent 
containing 35% of a principal component (produced by Orient Kagaku Kogyo 
K.K. and marketed under trademark designation of "Bontron S-34") and 5 
parts of aluminum chloride containing 5% of a principal component added 
thereto were heat treated at 95.degree. C. for three minutes, to afford 
blocks having the individual particles mutually fused. These blocks were 
separated by filtration and dried by the use of a reduced-pressure drier 
at 50.degree. C. for eight hours, to afford 1,700 parts of blocks having 
the individual particles fused in a state retaining the boundary surface 
thereof partially, possessing a bulk density of 0.22 g/cm.sup.3, and 
assuming the appearance of a cake of millet seeds glued with thick malt 
jelly. These block were fed at a rate of 18 kg/hr to an ultrasonic jet 
pulverizer (produced by Nippon Pneumatic Kogyo K.K. and marketed under 
product code of "IDS2 Type") and disintegrated therein, to give rise to 
microfine colored particles (3). 
The microfine colored particles (3), by measurement with a Coulter Counter 
(aperture 100 .mu.m), were found to possess an average particle diameter 
of 5.24 .mu.m and a coefficient of variation of particle diameter of 
19.8%. The microfine colored particles (3) were used in their unmodified 
forms as an electrophotographic toner to produce images by the use of an 
electrostatic copier (produced by Canon Co., Ltd. and marketed under 
product code of "NP-5000"). The results are shown in Table 1. 
Example 4 
A carbon black graft polymer was obtained by following the procedure of 
Example 1. In the same flask as described above, 8,970 parts of deionized 
water having dissolved therein 10 parts of an anionic surfactant (produced 
by Daiichi Seiyaku Co., Ltd. and marketed under trademark designation of 
"Hitenol N-08") was place. In the water, a mixture prepared in advance by 
combining 500 parts of carbon black graft polymer, 20 parts of 
azo-bis-isobutylonitrile, and 10 parts of 2,2'-azo-bis-(2,4-dimethyl 
valeronitrile) with a component consisting of 800 parts of styrene, 150 
parts of n-butyl acrylate, and 50 parts of polybutadiene (produced by 
Nippon Soda Co., Ltd. and marketed under trademark designation of 
"NISSO-PB-B-3000") was treated in the same manner as in Example 1, to give 
rise to a suspension (4) of microfine globular colored particles having a 
conversion of 92%, an average particle diameter of 6.30 .mu.m, and a 
coefficient of variation of particle diameter of 19.5%. 
When the suspension of microfine globular colored particles thus produced 
was heat treated at 90.degree. C. for two hours, they produced blocks of 
fused particles. These blocks were separated by filtration and dried by 
the use of a hot air drier at 50.degree. C. for 10 hours, to afford 1,500 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.31 
kg/cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. The block were fed at a rate of 17 kg/hr to an 
ultrasonic jet pulverizing device (produced by Nippon Pneumatic Kogyo K.K. 
and marketed under product code of "IDS2 Type") and disintegrated therein, 
to produce microfine colored particles (4). 
The microfine colored particles (4), by measurement with a Coulter Counter 
(aperture 100 .mu.m), were found to have an average particle diameter of 
6.14 .mu.m and a coefficient of variation of particle diameter of 20.8%. 
The microfine colored particles (4) were used in their unmodified forms as 
an electrophotographic toner to produce images with an electrostatic 
copier (produced by Ricoh Co., Ltd. and marketed under product code of 
"Type 4060"). The results are shown in Table 1. 
Example 5 
In the same flask as used in Example 1, 8,970 parts of deionized water 
having dissolved therein 5 parts of sodium dodecylbenzenesulfonate as an 
anionic surfactant was placed. In the water, a mixture prepared in advance 
by combining 500 parts of carbon black graft polymer as a coloring agent, 
30 parts of azo-bis-isobutylonitrile, and 30 parts of 
2,2'-azo-bis-(2,4-dimethyl valeronitrile) with a polymerizable monomer 
component consisting of 800 parts of styrene and 200 parts of n-butyl 
acrylate was stirred by the use of a mixing device (produced by Tokushu 
KikaKogyo K.K. and marketed under trademark designation of "T. K. 
Homomixer") at 8,000 rpm for five minutes, to form a homogeneous 
suspension. 
Then, the suspension was exposed to the blow of nitrogen gas and heated to 
65.degree. C., stirred continuously at this temperature for five hours to 
undergo suspension polymerization, and further heated at 75.degree. C. for 
one hour, to afford a suspension (5) of microfine globular colored 
particles having a conversion of 95.0%, an average particle diameter of 
5.92 .mu.m, and a coefficient of variation of particle diameter of 23.0%. 
When the suspension (5) of microfine globular colored particles kept at 
75.degree. C. and 200 parts of 1N hydrochloric acid added thereto were 
heat treated at 85.degree. C. for three hours, blocks of fused particles 
were obtained. These blocks were separated by filtration and dried by the 
use of a reduced-pressure drier at 50.degree. C. for eight hours, to 
afford 1,500 parts of blocks having the individual particles fused in a 
state retaining the boundary surface thereof intact, possessing a bulk 
density of 0.35 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. The blocks were fed at a rate of 
13 kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K.K. and marketed under product code of "IDS2 Type") and 
disintegrated therein, to produce microfine colored particles (5). 
The microfine colored particles (5) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.65 .mu.m and a coefficient of variation of particle 
diameter of 21.2%. The microfine colored particles (5) were used in their 
unmodified forms as an electrophotographic toner to produce images with an 
electrostatic copier (produced by Ricoh Co., Ltd. and marketed under 
product code of "Type 4060"). The results are shown in Table 1. 
Example 6 
A suspension (6) of microfine globular colored particles having a 
conversion of 92%, an average particle diameter of 6.02 .mu.m, and a 
coefficient of variation of particle diameter of 21.2% was obtained by 
following the procedure of Example 4, except 50 parts of chlorosulfonated 
polyethylene (produced by E. I. duPont de Nemors & Co. and marketed under 
trademark designation of "HYPOLON 20") was used in the place of 50 parts 
of polybutadiene and 30 parts of benzoyl peroxide was used in the place of 
20 parts of azo-bis-isobutylonitrile and 10 parts of 
2,2'-azo-bis-(2,4-dimethyl valeronitrile). When the suspension (6) of 
microfine globular colored particles kept at 75.degree. C. and 3 parts of 
calcium chloride added thereto were heat treated at 95.degree. C. for one 
hour, blocks of fused particles were formed. These blocks were separated 
by filtration and dried by the use of a reduced-pressure drier at 
50.degree. C. for eight hours, to afford 1,500 parts of blocks having the 
individual particles fused in a state retaining the boundary surface 
thereof partially, possessing a bulk density of 0.21 g/cm.sup.3, and 
assuming the appearance of a cake of millet seeds glued with thick malt 
jelly. The blocks were fed at a rate of 18 kg/hr to an ultrasonic jet 
pulverizing device (produced by Nippon Pneumatic Kogyo K.K. and marketed 
under product code of "IDS2 Type") and disintegrated therein, to produce 
microfine colored particles (6). 
The microfine colored particles (6) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 6.10 .mu.m and a coefficient of variation of particle 
diameter of 22.0%. The microfine colored particles (6) were used in their 
unmodified forms as an electrophotographic toner to produce images with an 
electrostatic copier (produced by Ricoh Co., Ltd. and marketed under 
product code of "Type 4060"). The results are shown in Table 1. 
Example 7 
A suspension (7) of microfine globular colored particles having a 
conversion of 96%, an average particle diameter of 5.75 .mu.m, and a 
coefficient of variation of particle diameter of 19.5% were obtained by 
following the procedure of Example 1, except 10 parts of a nonionic 
surfactant (produced by Sanyo Kasei K. K. and marketed under trademark 
designation of "Nonipol 200") was used in the place of 5 parts of sodium 
dodecylbenzenesulfonate as an anionic surfactant. When the suspension kept 
at 60.degree. C. and 750 parts of heptane added thereto were heat treated 
for one hour, blocks of fused particles were formed. These blocks were 
separated by filtration and dried by the use of a hot air drier at 
50.degree. C. for 10 hours, to afford 1,500 parts of blocks having the 
individual particles fused in a state retaining the boundary surface 
thereof partially, possessing a bulk density of 0.22 g/cm.sup.3, and 
assuming the appearance of a cake of millet seeds glued with thick malt 
jelly. These blocks were fed at a rate of 15 kg/hr to an ultrasonic jet 
pulverizing device (produced by Nippon Pneumatic Kogyo K.K. and marketed 
under product code of "IDS2 Type") and disintegrated therein, to produce 
microfine colored particles (7). 
The microfine colored particles (7) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.65 .mu.m and a coefficient of variation of particle 
diameter of 20.7%. The microfine colored particles (7) were used in their 
unmodified forms as an electrophotographic toner to produce images with an 
electrostatic copier (produced by Ricoh Co., Ltd. and marketed under 
product code of "Type 4060"). The results are shown in Table 1. 
Example 8 
The same suspension (1) of microfine globular colored particles was 
obtained as in Example 1. When the suspension (1) of microfine globular 
colored particles kept at 75.degree. C. and 500 parts of a dispersion 
prepared in advance by dispersing in 1,000 parts of deionized water 10 
parts of an electroconductive carbon black exhibiting a hydrophobicity 
index of 12.3 (produced by Ketjen International K.K. and marketed under 
trademark designation of "Ketjen EC") were heated for one hour, blocks of 
fused particles were obtained. These blocks were separated by filtration 
and dried by the use of a hot air drier at 50.degree. C. for 10 hours, to 
afford 1,500 parts of blocks having the individual particles fused in a 
state retaining the boundary surface thereof partially, possessing a bulk 
density of 0.18 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. The blocks were fed at a rate of 
16 kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K. K. and marketed under product code of "IDS2 Type") and 
disintegrated therein, to produce microfine colored particles (8). 
The microfine colored particles (8) thus produced, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.78 .mu.m and a coefficient of variation of particle 
diameter of 17.5%. The microfine colored particles (8) were used in their 
unmodified forms as an electrophotographic toner to produce images with an 
electrostatic copier (produced by Ricoh Co., Ltd. and marketed under 
product code of "Type 4060"). The results are shown in Table 1. 
Example 9 
Blocks of particles were formed by following the procedure of Example 8, 
except 123.8 parts of a dispersion prepared in advance by dispersing 10 
parts of hydrophobic aerosil exhibiting a hydrophobicity index of 50.5 
(produced by Nippon Aerosil K.K.) and 5 parts of an electroconductive 
carbon black exhibiting a hydrophobicity index of 12.3 (produced by Ketjen 
International K. K. and marketed under trademark designation of "Ketjen 
EC") in 150 parts of methanol was added instead of adding 500 parts of the 
aqueous dispersion of Ketjen EC and a heat treatment was additionally 
formed for 1.5 hours. The blocks were separated by filtration and dried by 
the use of a reduced-pressure drier at 50.degree. C. for eight hours, to 
afford 1,500 parts of blocks having the individual particles fused in a 
state retaining the boundary surface thereof partially, possessing a bulk 
density of 0.17 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. These blocks were fed at a rate 
of 20 kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K. K. and marketed under product code of "IDS2 Type") and 
disintegrated therein, to produce microfine colored particles (9). 
The microfine colored particles (9) thus produced, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to have an average 
particle diameter of 5.81 .mu.m and a coefficient of variation of particle 
diameter of 17.1%. The microfine colored particles (9) were used in their 
unmodified forms as an electrophotographic toner (9) to produce images 
with an electrostatic copier (produced by Canon Co., Ltd. and marketed 
under product code of "NP-5000"). The results are shown in Table 1. 
Example 10 
The same suspension (2) of microfine globular colored particles was 
obtained as in Example 2. When the suspension (2) of microfine globular 
colored particles kept at 75.degree. C. and 82.5 parts of a dispersion 
prepared in advance by dispersing 13 parts of an aqueous-paste charge 
controlling agent containing 35% of a principal component (produced by 
Orient Kagaku Kogyo K. K. and marketed under trademark designation of 
"Bontron S-34") and 10 parts of a hydrophobic aerosil R972 (produced by 
Nippon Aerosil K.K.) in 100 parts of methanol were heat treated at 
95.degree. C. for one hour, blocks of fused particles were formed. These 
blocks were separated by filtration and dried by the use of a 
reduced-pressure drier at 50.degree. C. for eight hours, to afford 1,110 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.26 
g/cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. The blocks were fed at a rate of 13 kg/hr to an 
ultrasonic jet pulverizing device (produced by Nippon Pneumatic Kogyo K. 
K. and marketed under product code of "IDS2 Type") and disintegrated 
therein, to produce microfine colored particles (10). 
The microfine colored particles (10) thus produced, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to have an average 
particle diameter of 6.35 .mu.m and a coefficient of variation of particle 
diameter of 19.0%. This microfine colored particles (10) were used in 
their unmodified forms as an electrophotographic toner to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 11 
The same suspension (3) of microfine globular colored particles was 
obtained as in Example 3. When the suspension (3) of microfine globular 
colored particles kept at 75.degree. C. and 110 parts of a dispersion 
prepared in advance by dispersing 41 parts of an aqueous-paste charge 
controlling agent containing 35% of a principal component (produced by 
Orient Kagaku Kogyo K. K. and marketed under trademark designation of 
"Bontron S34") and 10 parts of aerosil exhibiting a hydrophobicity index 
of 69.5 (produced by Nippon Aerosil K. K.) in 100 parts of methanol were 
heat treated at 95.degree. C. for 30 minutes, blocks of fused particles 
were obtained. These blocks were separated by filtration and dried by the 
use of a reduced-pressure drier at 50.degree. C. for eight hours, to 
afford 1700 parts of blocks having the individual particles fused in a 
state retaining the boundary surface thereof partially, possessing a bulk 
density of 0.20 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. These blocks were fed at a rate 
of 20 kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K.K. and marketed under product code of "IDS2 Type") and 
disintegrated therein, to produce microfine colored particles (11). 
The microfine colored particles (11) thus produced, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to have an average 
particle diameter of 5.24 .mu.m and a coefficient of variation of particle 
diameter of 19.8%. The microfine colored particles (11) were used in their 
unmodified forms as an electrophotographic toner to produce images with an 
electrostatic copier (produced by Canon Co., Ltd. and marketed under 
product code of "NP-5000"). The results are shown in Table 1. 
Example 12 
The same suspension (4) of microfine globular colored particles was 
obtained as in Example 4. When the suspension (4) of microfine globular 
colored particles and 20 parts of antimony oxide-doped tin oxide (produced 
by Mitsubishi Metal Corp. and marketed under product code of "T- 1") added 
thereto were heat treated at 90.degree. C. for two hours, blocks of fused 
particles were obtained. The blocks were separated by filtration and dried 
by the use of a hot air drier at 50.degree. C. for 10 hours, to afford 
1,500 parts of blocks having the individual particles fused in a state 
retaining the boundary surface thereof partially, possessing a bulk 
density of 0.30 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. These blocks were fed at a rate 
of 18 kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K.K. and marketed under product code of "IDS2 Type") and 
disintegrated therein, to produce microfine colored particles (12). 
The microfine colored particles (12) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 6.20 .mu.m and a coefficient of variation of particle 
diameter of 20.0%. The microfine colored particles (12) were used in their 
unmodified forms as an electrophotographic toner (12) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 13 
The same suspension (5) of microfine globular colored particles was 
obtained as in Example 5. To the suspension (5) of microfine globular 
colored particles, 100 parts of heptane and 100 parts of a dispersion 
prepared in advance by dispersing in 100 parts of methanol 10 parts of 
microfine water-insoluble particles produced by treating titanium oxide 
(produced by Nippon Aerosil K. K. and marketed under product code of 
"P25") until it acquired a hydrophobicity index of 15 were added. After 
these additions, the suspension was heat treated at 85.degree. C. for 
three hours, which resulted in the formation of blocks of fused particles. 
The blocks were separated by filtration and dried by the use of a 
reduced-pressure drier at 50.degree. C. for eight hours, to afford 1500 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.34 
g/cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. These blocks were fed at a rate of 13 kg/hr to an 
ultrasonic jet pulverizing device (produced by Nippon Pneumatic Kogyo K.K. 
and marketed under product code of "IDS2 Type") and disintegrated therein, 
to produce microfine colored particles (13). The microfine colored 
particles (13) thus obtained, by measurement with a Coulter Counter 
(aperture 100 .mu.m), were found to possess an average particle diameter 
of 5.73 .mu.m and a coefficient of variation of particle diameter of 
20.5%. The microfine colored particles (13) were used in their unmodified 
forms as an electrophotographic toner to produce images with an 
electrostatic copier (produced by Ricoh Co., Ltd. and marketed under 
product code of "Type 4060"). The results are shown in Table 1. 
Example 14 
The same suspension (6) of microfine globular colored particles was 
obtained as in Example 6. To the suspension (6) of microfine globular 
colored particles, 180 parts of a dispersion prepared in advance by 
dispersing in 150 parts of methanol 15 parts of zirconium oxide (produced 
by Nippon Shokubai Kagaku Kogyo Co., Ltd. and marketed under product code 
of "NS-3Y") and 15 parts of a powdered magnetic material (produced by 
Titan Kogyo K.K. and marketed under trademark designation of "Mapico 
BL-400") were added. After these additions, the suspension was heat 
treated at 95.degree. C. for one hour, which resulted in the formation of 
blocks of fused particles. These blocks were separated by filtration and 
dried by the use of a reduced-pressure drier at 50.degree. C. for eight 
hours, to afford 1,500 parts of blocks having the individual particles 
fused in a state retaining the boundary surface thereof intact, possessing 
a bulk density of 0.19 g/cm.sup.3, and assuming the appearance of a cake 
of millet seeds glued with thick malt jelly. These blocks were fed at a 
rate of 19.5 kg/hr to an ultrasonic jet pulverizing device (produced by 
Nippon Pneumatic Kogyo K. K. and marketed under product code of "IDS2 
Type") and disintegrated therein, to produce microfine colored particles 
(14). The microfine colored particles (14) thus obtained, by measurement 
with a Coulter Counter (aperture 100 .mu.m), were found to have an average 
particle diameter of 6.21 .mu.m and a coefficient of variation of particle 
diameter of 21.5%. The microfine colored particles (14) were used in their 
unmodified forms as an electrophotographic toner (14) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 15 
The same suspension (7) of microfine globular colored particles was 
obtained as in Example 7. To this suspension kept at 60.degree. C., 200 
parts of heptane and 313 parts of a dispersion prepared in advance by 
dispersing in 285 parts of methanol 12 parts of hydrophobic aerosil 
exhibiting a hydrophobicity index of 64.5 (produced by Nippon Aerosil K. 
K. and marketed under product code of "R809"), 12 parts of a hydrophobic 
aerosil exhibiting a hydrophobicity index of 50 (produced by Nippon 
Aerosil K. K. and marketed under product code of "R805"), and 4.5 parts of 
an electroconductive carbon black (produced by Ketjen International K. K. 
and marketed under trademark designation of "Ketjen EC") were added. After 
these additions, the suspension was heat treated at 60.degree. C. for 2 
hr, which resulted in the formation of blocks of fused particles. The 
blocks were separated by filtration and dried by the use of a hot air 
drier at 50.degree. C. for 10 hours, to afford 1,500 parts of blocks 
having the individual particles fused in a state retaining the boundary 
surface thereof intact, possessing a bulk density of 0.21 g/cm.sup.3, and 
assuming the appearance of a cake of millet seeds glued with thick malt 
jelly. These blocks were fed at a rate of 16 kg/hr to an ultrasonic jet 
pulverizing device (produced by Nippon Pneumatic Kogyo K. K. and marketed 
under product code of "IDS2 Type"), to produce microfine colored particles 
(15). 
The microfine colored particles (15) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.65 .mu.m and a coefficient of variation of particle 
diameter of 20.7%. The microfine colored particles (15) were used in their 
unmodified forms as an electrophotographic toner (25) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 16 
A suspension (1') of microfine globular colored particles having an average 
particle diameter of 5.82 .mu.m and a coefficient of variation of particle 
diameter of 20.5% was obtained by following the procedure of Example 1, 
except the mixture containing the polymerizable monomer component, instead 
of being treated with the T. K. Homomixer, was passed five times through a 
mixing device (produced by Ebara Mfg. Co., Ltd. and marketed under 
trademark designation of "Ebara Milder MDN-303V") operated at 15,000 rpm 
to form a homogeneous suspension and the suspension polymerization 
reaction was performed by heating the suspension at 65.degree. C. for 5 
hour, and further at 75.degree. C. for two hours. The suspension and 60 
parts of an aqueous aluminum chloride solution containing 5% of the 
principal component were mixed to induce cohesion of microfine globular 
colored particles. The resultant cake was separated by use of a centrifuge 
and then heated and humidified for 10 minutes in an atmosphere kept at 
90.degree. C. and a relative humidity of 98%, to form a mass of blocks of 
fused particles. The blocks were dried at 50.degree. C., to afford 1,500 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.4 
g/cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. These blocks were coarsely crushed and then fed at 
a rate of 11 kg/hr to an ultrasonic jet pulverizing device (produced by 
Nippon Pneumatic Kogyo K.K. and marketed under product code of "IDS2 
Type") and disintegrated therein, to produce microfine colored particles 
(16). 
The microfine colored particles (16) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.65 .mu.m and a coefficient of variation of particle 
diameter of 18.8%. This microfine colored particles (16) were used in 
their unmodified forms as an electrophotographic toner (16) to produce 
images with an electrostatic copier (produced by Ricoh Co., Ltd. and 
marketed under product code of "Type 4060"). The results are shown in 
Table 1. 
Example 17 
A suspension (2') of microfine globular colored particles having an average 
particle diameter of 6.42 .mu.m and a coefficient of variation of particle 
diameter of 21.3% was obtained by following the procedure of Example 2, 
except the reaction of suspension polymerization was carried out at 
65.degree. C. for five hours and then at 75.degree. C. for 2 hours. The 
suspension (2') of microfine globular colored particles kept at 75.degree. 
C. was combined first with 13 parts of an aqueous-paste charge controlling 
agent containing 35% of a principal component (produced by Orient Kagaku 
Kogyo K.K. and marketed under trademark designation of "Bontron S-34") and 
then with 1,110 parts of methanol to induce sedimentation of microfine 
globular colored particles. The resultant cake was separated by filtration 
and heated and humidified for 20 minutes in an atmosphere kept at 
80.degree. C. and a relative humidity of 90%, to form a mass of blocks of 
fused particles. These blocks were dried at 50.degree. C., to afford 1,110 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.70 
g/cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. These blocks were coarsely crushed and then fed at 
a rate of 8.0 kg/hr to an ultrasonic jet pulverizing device (produced by 
Nippon Pneumatic Kogyo K. K. and marketed under product code of "IDS2 
Type") and disintegrated therein, to produce microfine colored particles 
(17). The microfine colored particles (17) thus obtained, by measurement 
with a Coulter Counter (aperture 100 .mu.m), were found to possess an 
average particle diameter of 6.15 .mu.m and a coefficient of variation of 
particle diameter of 23.3%. The microfine colored particles (17) were used 
in their unmodified forms as an electrophotographic toner (17) to produce 
images with an electrostatic copier (produced by Ricoh Co., Ltd. and 
marketed under product code of "Type 4060"). The results are shown in 
Table 1. 
Example 18 
A suspension (3') of microfine globular colored particles possessing an 
average particle diameter of 5.43 .mu.m and a coefficient of variation of 
particle diameter of 22.5% was obtained by following the procedure of 
Example 3, except the reaction of suspension polymerization was carried 
out first at 65.degree. C. for five hours and then at 75.degree. C. for 
two hours. The suspension (3') of microfine globular colored particles 
kept at 75.degree. C. was combined with 41 parts of an aqueous-paste 
charge controlling agent containing 35% of a principal component (produced 
by Orient Kagaku Kogyo K.K. and marketed under trademark designation of 
"Bontron S-34") and 60 parts of an aqueous aluminum chloride solution 
containing 5% of a principal component to induce cohesion of microfine 
globular colored particles. The resultant cake was separated by filtration 
and then heated and humidified for five minutes in an atmosphere kept at 
95.degree. C. and a relative humidity of 100%, to form a mass of blocks of 
fused particles. These blocks were dried at 50.degree. C., to afford 1,700 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.35 
g/cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. The blocks were coarsely crushed and then fed at a 
rate of 13 kg/hr to an ultrasonic jet pulverizing device (produced by 
Nippon Pneumatic Kogyo K.K. and marketed under product code of "IDS3 
Type") and disintegrated therein, to produce microfine colored particles 
(3). 
The microfine colored particles (18) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.22 .mu.m and a coefficient of variation of particle 
diameter of 19.3%. The microfine colored particles (18) were used in its 
unmodified form as an electrophotographic toner (18) to produce images 
with an electrostatic copier (produced by Canon Co., Ltd. and marketed 
under product code of "NP-500"). The results are shown in Table 1. 
Example 19 
A suspension (4') of microfine globular colored particles having an average 
particle diameter of 6.30 .mu.m and a coefficient of variation of particle 
diameter of 19.5% was obtained by following the procedure of Example 4, 
except the reaction of suspension polymerization was carried out first at 
65.degree. C. for five hours and then at 75.degree. C. for two hours. The 
suspension (4') of microfine globular colored particles was combined with 
60 parts of an aqueous aluminum chloride solution containing 5% of a 
principal component to induce cohesion of the microfine globular colored 
particles. The resultant cake was separated by filtration and heated and 
humidified for 20 minutes in an atmosphere kept at 85.degree. C. and a 
relative humidity of 100%, to form a mass of blocks of fused particles. 
These blocks were dried at 50.degree. C., to afford 1,500 parts of blocks 
having the individual particles fused in a state retaining the boundary 
surface thereof partially, possessing a bulk density of 0.31 g/cm.sup.3, 
and assuming the appearance of a cake of millet seeds glued with thick 
malt jelly. These blocks were coarsely crushed and then fed at a rate of 
15 kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K. K. and marketed under product code of "IDS2 Type") and 
disintegrated therein, to produce microfine colored particles (19). 
The microfine colored particles (19) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 6.24 .mu.m and a coefficient of variation of particle 
diameter of 20.8%. The microfine colored particles (19) were used in their 
unmodified forms as an electrophotographic toner (19) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 20 
A suspension (5') of microfine globular colored particles having an average 
particle diameter of 5.92 .mu.m and a coefficient of variation of particle 
diameter of 23.0% was obtained by following the procedure of Example 5, 
except the reaction of suspension polymerization was carried out first at 
65.degree. C. for five hours and then at 75.degree. C. for two hours. This 
suspension was combined with 1,500 parts of methanol to induce 
sedimentation of the microfine globular colored particles. The resultant 
cake was separated by filtration and heated and humidified for 35 minutes 
in an atmosphere kept at 70.degree. C. and a relative humidity of 95%, to 
form a mass of blocks of fused particles. These blocks were dried at 
50.degree. C., to afford 1,500 parts of blocks having the individual 
particles fused in a state retaining the boundary surface thereof 
partially, possessing a bulk density of 0.55 g/cm.sup.3, and assuming the 
appearance of a cake of millet seeds glued with thick malt jelly. These 
blocks were coarsely crushed and then fed at a rate of 10.5 kg/hr to an 
ultrasonic jet pulverizing device (produced by Nippon Pneumatic Kogyo K. 
K. and marketed under product code of "IDS2 Type") and disintegrated 
therein, to produce microfine colored particles (20). 
The microfine colored particles (20) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.67 .mu.m and a coefficient of variation of particle 
diameter of 21.5%. The microfine colored particles (20) were used in their 
unmodified forms as an electrophotographic toner (20) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 21 
A suspension (6') of microfine globular colored particles having an average 
particle diameter of 6.02 .mu.m and a coefficient of variation of particle 
diameter of 21.2% was obtained by following the procedure of Example 6, 
except the reaction of suspension polymerization was carried out first at 
65.degree. C. for five hours and then at 75.degree. C. for two hours. This 
suspension was combined with 180 parts of an aqueous calcium chloride 
solution containing 5% of a principal component to induce cohesion of 
microfine globular colored particles. The resultant cake was separated by 
filtration and heated and humidified for three minutes in an atmosphere 
kept at 110.degree. C. and a relative humidity of 100%, to form a mass of 
blocks of fused particles. These blocks were dried at 50.degree. C., to 
afford 1500 parts of blocks having the individual particles fused in a 
state retaining the boundary surface thereof partially, possessing a bulk 
density of 0.51 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. These blocks were coarsely 
crushed and then fed at a rate of 9.5 kg/hr to an ultrasonic jet 
pulverizing device (produced by Nippon Pneumatic Kogyo K.K. and marketed 
under product code of "IDS2 Type") and disintegrated therein, to produce 
microfine colored particles (21). 
The microfine colored particles (21) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 6.15 .mu.m and a coefficient of variation of particle 
diameter of 22.5%. The microfine colored particles (21) were used in their 
unmodified forms as an electrophotographic toner (21) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 22 
A suspension (7') of microfine globular colored particles having an average 
particle diameter of 5.75 .mu.m and a coefficient of variation of particle 
diameter of 19.5% was obtained by following the procedure of Example 7, 
except the reaction of suspension polymerization was carried out first at 
65.degree. C. for five hours and then at 75.degree. C. for two hours. This 
suspension was combined with 180 parts of an aqueous Aluminium chloride 
solution containing 5% of a principal component to induce cohesion of 
microfine globular colored particles. The resultant cake was separated by 
filtration and heated and humidified for 15 minutes in an atmosphere kept 
at 85.degree. C. and a relative humidity of 90%, to form a mass of blocks 
of fused particles. These blocks were dried at 50.degree. C., to afford 
1,500 parts of blocks having the individual particles fused in a state 
retaining the boundary surface thereof partially, possessing a bulk 
density of 0.62 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. These blocks were coarsely 
crushed and then fed at a rate of 7 kg/hr to an ultrasonic jet pulverizing 
device (produced by Nippon Pneumatic Kogyo K. K. and marketed under 
product code of "IDS2 Type") and disintegrated therein, to produce 
microfine colored particles (22). 
The microfine colored particles (22) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.65 .mu.m and a coefficient of variation of particle 
diameter of 21.7%. The microfine colored particles (22) were used in their 
unmodified forms as an electrophotographic toner (22) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 23 
A cake of solids of fused particles was obtained by following the procedure 
of Example 16, except 82.5 parts of a dispersion of 10 parts of a 
hydrophobic aerosil (produced by Nippon Aerosil K. K. and marketed under 
product code of "R972") in 100 parts of methanol was used in the place of 
60 parts of an aqueous aluminum chloride solution containing 5% of a 
principal component. 
Thereafter, by following the procedure of Example 16, there were obtained 
1,500 parts of blocks having the individual particles fused in a state 
retaining the boundary surface thereof partially, possessing a bulk 
density of 0.39 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. The blocks were coarsely crushed 
and then fed at a rate of 10 kg/hr to an ultrasonic jet pulverizing device 
(produced by Nippon Pneumatic Kogyo K. K. and marketed under product code 
of "IDS2 Type") and disintegrated therein, to produce microfine colored 
particles (23). 
The microfine colored particles (23) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.64 .mu.m and a coefficient of variation of particle 
diameter of 18.7 %. The microfine colored particles (23) were used in 
their unmodified forms in an electrophotographic toner (23) to produce 
images with an electrostatic copier (produced by Ricoh Co., Ltd. and 
marketed under product code of "Type 4060"). The results are shown in 
Table 1. 
Separately, a cake was obtained by following the procedure described above 
in effecting the cohesion of microfine globular colored particles and the 
separation thereof by filtration. This cake, without undergoing the 
heating and humidifying treatments, was dried to form blocks having a bulk 
density of 0.33 g/cm.sup.3. The blocks were disintegrated by the use of a 
hammer mill, to produce microfine colored particles (23'). The microfine 
colored particles each had very high spherality. The microfine colored 
particles (23') were determined for triboelectricity. The results are 
shown in Table 2. 
Example 24 
A suspension (1') of microfine globular colored particles was obtained by 
following the procedure of Example 8. This suspension was combined with 60 
parts of an aqueous aluminum chloride solution containing 5% of a 
principal component to induce cohesion of the microfine globular colored 
particles. The blocks of particles consequently formed were filtered with 
a continuous type suction filter. The cake obtained on the filter was 
washed and, at the same time, heated by continuous addition thereto of 
5,000 parts of hot water at 85.degree. C., to form a mass of blocks of 
fused particles. These blocks were dried at 50.degree. C., to afford 1,500 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.42 
g/ cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. The blocks were coarsely crushed and then fed at a 
rate of 11 kg/hr to an ultrasonic jet pulverizing device (produced by 
Nippon Pneumatic Kogyo K. K. and marketed under product code of "IDS2 
Type") and disintegrated therein, to produce microfine colored particles 
(24). 
The microfine colored particles (24) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.60 .mu.m and a coefficient of variation of particle 
diameter of 18.7%. The microfine colored particles (24) were used in their 
unmodified forms as an electrophotographic toner (24) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 25 
A suspension (2') of microfine globular colored particles was obtained by 
following the procedure of Example 10. The suspension (2') of microfine 
globular colored particles was combined first with 13 parts of an 
aqueous-paste charge controlling agent containing 35% of a principal 
component (produced by Orient Kagaku Kogyo K.K. and marketed under 
trademark designation of "Bontron S-34") and then with 1,110 parts of 
methanol to induce sedimentation of the microfine globular colored 
particles. A mass of sedimented particles was filtered with a continuous 
type suction filter. The cake stopped on the filter was heated by 
continuous addition thereto of 4,000 parts of hot water at 80.degree. C., 
to form a mass of blocks of fused particles. The blocks were dried at 
50.degree. C., to afford 1,110 parts of blocks having the individual 
particles fused in a state retaining the boundary surface thereof 
partially, possessing a bulk density of 0.70 g/cm.sup.3, and assuming the 
appearance of a cake of millet seeds glued with thick malt jelly. The 
blocks were coarsely crushed and fed at a rate of 8.0 kg/hr to an 
ultrasonic jet pulverizing device (produced by Nippon Pneumatic Kogyo K. 
K. and marketed under product code of "IDS2 Type") and disintegrated 
therein, to produce microfine colored particles (25). 
The microfine colored particles (25) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 6.18 .mu.m and a coefficient of variation of particle 
diameter of 23.0%. The microfine colored particles (25) were used in their 
unmodified forms as an electrophotographic toner (25) to produce images 
with an electrostatic copier (produced by Ricoh Co. Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 26 
A suspension (3') of microfine globular colored particles was obtained by 
following the procedure of Example 11. The suspension (3') of microfine 
globular colored particles was combined with 41 parts of an aqueous-paste 
charge controlling agent containing 35% of a principal component (produced 
by Orient Kagaku Kogyo Co., Ltd. and marketed under trademark designation 
of "Bontron S-34") and 60 parts of an aqueous aluminum chloride solution 
containing 5% of a principal component to induce cohesion of the microfine 
globular colored particles. The blocks of particles consequently formed 
were filtered with a continuous pressure filter. The cake stopped on the 
filter was washed and, at the same time, heated by continuous addition 
thereto of 3,000 parts of hot water at 110.degree. C., to form a mass of 
blocks of fused particles. These blocks were dried at 50.degree. C., to 
afford 1,700 parts of blocks having the individual particles fused in a 
state retaining the boundary surface thereof partially, possessing a bulk 
density of 0.35 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. The blocks were coarsely crushed 
and then fed at a rate of 13 kg/hr to an ultrasonic jet pulverizing device 
(produced by Nippon Pneumatic Kogyo K. K. and marketed under product code 
of "IDS2 Type") and disintegrated therein, to produce microfine colored 
particles (26). 
The microfine colored particles (26) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.24 .mu.m and a coefficient of variation of particle 
diameter of 19.0%. The microfine colored particles (26) were used in their 
unmodified forms as an electrophotographic toner (26) to produce images 
with an electrostatic copier (produced by Canon Co., Ltd. and marketed 
under product code of "NP-5000"). The results are shown in Table 1. 
Example 27 
A suspension (4') of microfine globular colored particles was obtained by 
following the procedure of Example 12. The suspension (4') of microfine 
globular colored particles was combined with 60 parts of an aqueous 
aluminum chloride solution containing 5% of a principal component to 
induce cohesion of the microfine globular colored particles. The blocks of 
fused particles consequently obtained were subjected to separation with a 
centrifugal separator. The resultant cake stopped on the centrifugal 
separator was washed and, at the same time, heated by continuous addition 
thereto of 4,500 parts of hot water at 85.degree. C., to form a mass of 
blocks of fused particles. These blocks were dried at 50.degree. C., to 
afford 1,500 parts of blocks having the individual particles fused in a 
state retaining the boundary surface thereof partially, possessing a bulk 
density of 0.33 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly. The blocks were coarsely crushed 
and then fed at a rate of 15 kg/hr to an ultrasonic jet pulverizing device 
(produced by Nippon Pneumatic Kogyo K. K. and marketed under product code 
of "IDS2 Type") and disintegrated therein, to produce microfine colored 
particles (27). 
The microfine colored particles (27) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 6.23 .mu.m and a coefficient of variation of particle 
diameter of 20.5%. The microfine colored particles (27) were used in their 
unmodified forms as an electrophotographic toner (27) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 28 
A suspension (5') of microfine globular colored particles was obtained by 
following the procedure of Example 13. This suspension was combined with 
1,500 parts of methanol to induce sedimentation of the microfine globular 
colored particles. The blocks of particles consequently formed were 
subjected to filtration with a centrifugal separator. The cake 
consequently stopped on the centrifugal separator was washed and, at the 
same time, heated by continuous addition thereto of 6,000 parts of hot 
water at 75.degree. C., to form a mass of blocks of fused particles. These 
blocks were dried at 50.degree. C., to afford 1,500 parts of blocks having 
the individual particles fused in a state retaining the boundary surface 
thereof partially, possessing a bulk density of 0.55 g/cm.sup.3, and 
assuming the appearance of a cake of millet seeds glued with thick malt 
jelly. The blocks were coarsely crushed and then fed at a rate of 10.5 
kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K. K. and marketed under a product code of "IDS2 Type") 
and disintegrated therein, to produce microfine colored particles (28). 
The microfine colored particles (28) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.65 .mu.m and a coefficient of variation of particle 
diameter of 21.6%. This microfine colored particles (28) were used in 
their unmodified forms as an electrophotographic toner (28) to produce 
images with an electrostatic copier (produced by Ricoh Co., Ltd. and 
marketed under product code of "Type 4060"). The results are shown in 
Table 1. 
Example 29 
A suspension (6') of microfine globular colored particles was obtained by 
following the procedure of Example 14. This suspension (6') was combined 
with 180 parts of an aqueous calcium chloride solution containing 5% of a 
principal component to induce cohesion. The blocks of particles 
consequently formed were subjected to filtration with a continuous 
pressure filter. The particles stopped on the filter were washed and, at 
the same time, heated by continuous addition thereto of 4,000 parts of hot 
water at 115.degree. C., to form a mass of blocks of fused particles. 
These blocks were dried at 50.degree. C., to afford 1,500 parts of blocks 
having the individual particles fused in a state retaining the boundary 
surface thereof partially, possessing a bulk density of 0.58 g/cm.sup.3, 
and assuming the appearance of a cake of millet seeds glued with thick 
malt jelly. The blocks were coarsely crushed and then fed at a rate of 9.5 
kg/hr to an ultrasonic jet pulverizing device (produced by Nippon 
Pneumatic Kogyo K.K. and marketed under product code of "IDS2 Type") and 
disintegrated therein, to produce microfine colored particles (29). 
The microfine colored particles (29) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 6.12 .mu.m and a coefficient of variation of particle 
diameter of 22.3%. The microfine colored particles (29) were used in their 
unmodified forms as an electrophotographic toner (29) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 30 
A suspension (7') of microfine globular colored particles was obtained by 
following the procedure of Example 15. This suspension (7') was combined 
with 1,500 parts of methanol and 1,000 parts of industrial grade ethanol 
to induce sedimentation of the colored particles. The sedimented particles 
were subjected to filtration with a continuous suction filter. The cake 
consequently stopped on the filter was heated by continuous addition of 
2,500 parts of hot water at 90.degree. C., to form a mass of blocks of 
fused particles. These blocks were dried at 50.degree. C., to afford 1,500 
parts of blocks having the individual particles fused in a state retaining 
the boundary surface thereof partially, possessing a bulk density of 0.62 
g/cm.sup.3, and assuming the appearance of a cake of millet seeds glued 
with thick malt jelly. The blocks were coarsely crushed and then fed at a 
rate of 7 kg/hr to an ultrasonic jet pulverizing device (produced by 
Nippon Pneumatic Kogyo K.K. and marketed under product code of "IDS2 
Type") and disintegrated therein, to produce microfine colored particles 
(30). 
The microfine colored particles (30) thus obtained, by measurement with a 
Coulter Counter (aperture 100 .mu.m), were found to possess an average 
particle diameter of 5.61 .mu.m and a coefficient of variation of particle 
diameter of 21.5%. The microfine colored particles (30) were used in their 
unmodified forms as an electrophotographic toner (30) to produce images 
with an electrostatic copier (produced by Ricoh Co., Ltd. and marketed 
under product code of "Type 4060"). The results are shown in Table 1. 
Example 31 
A cake of blocks of fused particles was obtained by following the procedure 
of Example 24 in effecting the cohesion of microfine globular colored 
particles and the separation of the fused particles by filtration, except 
143 parts of a dispersion prepared in advance by dispersing 10 parts of a 
hydrophobic aerosil (produced by Nippon Aerosil K. K. and marketed under 
product code of "R972") and 3 parts of an electroconductive carbon black 
Ketjen EC (produced by Ketjen International K.K.) in 130 parts of methanol 
was used in the place of 60 parts of the aqueous aluminum chloride 
solution containing 5% of a principal component. 
Thereafter, 1,500 parts of blocks having the individual particles fused in 
a state retaining the boundary surface thereof partially, possessing a 
bulk density of 0.30 g/cm.sup.3, and assuming the appearance of a cake of 
millet seeds glued with thick malt jelly were obtained by following the 
procedure of Example 24. The blocks were coarsely crushed and then fed at 
a rate of 12 kg/hr to an ultrasonic jet pulverizing device (produced by 
Nippon Pneumatic Kogyo K. K. and marketed under product code of "IDS2 
Type") and disintegrated therein, to produce microfine colored particles 
(31). The microfine colored particles (31) thus obtained, by measurement 
with a Coulter Counter (aperture 100 .mu.m), were found to possess an 
average particle diameter of 5.45 .mu.m and a coefficient of variation of 
particle diameter of 17.8%. The microfine colored particles (31) were used 
in their unmodified forms as an electrophotographic toner (31) to produce 
images with an electrostatic copier (produced by Ricoh Co., Ltd. and 
marketed under product code of "Type 4060"). The results are shown in 
Table 1. 
Separately, a cake of blocks of fused particles was obtained by following 
the procedure described above in effecting the cohesion of microfine 
colored particles and the separation thereof by filtration. When this cake 
was dried without preliminarily undergoing the heating and humidifying 
treatments, there were formed blocks which had a bulk density of 0.26 
g/cm.sup.3. This cake was disintegrated by the use of a hammer mill, to 
produce microfine colored particles (31'). The microfine colored particles 
each had extremely high spherality. The microfine colored particles (31') 
were determined for triboelectricity. The results are shown in Table 2. 
Control 1 
Blocks of fused particles were formed by keeping 10,480 parts of the 
suspension (4) of microfine globular colored particles obtained in Example 
4 at 75.degree. C., adding 5 parts of aluminum chloride to the hot 
suspension, and heat treating the resultant mixture at 150.degree. C. 
under an increased pressure for 30 minutes. These blocks were separated by 
filtration, dried by the use of a reduced-pressure drier at 50.degree. C. 
for eight hours, coarsely crushed, fed at a rate of 4 kg/hr to the same 
ultrasonic jet pulverizing device and disintegrated therein, to produce 
1,500 parts of microfine colored particles (a) for comparison. 
The microfine colored particles (a) were tested for properties as a 
particulate substance. The microfine colored particles (a) were used in 
their unmodified forms as an electrophotographic toner (a) for comparison 
to produce images with an electrostatic copier (produced by Ricoh Co., 
Ltd. and marketed under product code of "Type 4060"). The results are 
shown in Table 1. 
Control 2 
A suspension of microfine globular colored particles was obtained by 
following the procedure of Example 4, except the reaction of suspension 
polymerization was carried out at 65.degree. C. for four hours and the 
conversion, therefore, was 86%. When the suspension of microfine globular 
colored particles was further heat treated at 90.degree. C. for two hours, 
there was formed a large aggregate of microfine globular colored particles 
as a whole. The aggregate did not easily succumb to the subsequent 
treatments. 
Control 3 
A toner mass was obtained by premixing 2,228 parts of styrene-acryl resin 
(produced by Sanyo Kasei K. K. and marketed under product code of 
"TB-1000F"), 187 parts of carbon black (produced by Mitsubishi Chemical 
Industry Co., Ltd. and marketed under product code of "MA-100R"), and 25 
parts of a charge controlling agent (produced by Hodogaya Chemical Co., 
Ltd. and marketed under trademark designation of "Aizen Spilon Black TRH") 
by the use of a pressure kneader at 150.degree. C. for 30 minutes and 
cooling the resultant premix. The toner mass was coarsely crushed with a 
coarse crushing device into particles 0.1 to 2 mm in diameter, the 
resultant coarse toner particles were fed at a rate of 5 kg/hr to the same 
ultrasonic jet pulverizing device as used in Example 1 and finely 
disintegrated therein, and the resultant microfine toner particles were 
classified with a wind classifier (produced by Nippon Pneumatic Kogyo K. 
K. and marketed under product code of "DS-2 Type"), to produce 1,500 parts 
of microfine colored particles (b) for comparison. 
The microfine colored particles (b) for comparison were tested for 
properties as a particulate substance. The microfine colored particles (b) 
for comparison were used in their unmodified forms as an 
electrophotographic toner (b) to produce images with an electrostatic 
copier (produced by Ricoh Co., Ltd. and marketed under product code of 
"Type 4060"). The results are shown in Table 1. 
Control 4 
A mass of blocks of fused particles was formed by preparing a cake of 
microfine globular colored particles in accordance with the procedure of 
Example 19 and heat treating this cake in a compressed atmosphere kept at 
140.degree. C. and a relative humidity of 100%. By drying this mass at 
50.degree. C., 1,500 parts of blocks were obtained. By coarsely crushing 
these blocks and then feeding the crushed particles at a rate of 2 kg/hr 
to the same device as used in Example 4 and disintegrating them therein, 
there was produced microfine colored particles (c) for comparison. 
The microfine colored particles (c) for comparison were tested for 
properties as a particulate substance. The microfine colored particles (c) 
for comparison were used in their unmodified forms as an 
electrophotographic toner (c) to produce images with an electrostatic 
copier (produced by Ricoh Co., Ltd. and marketed under product code of 
"Type 4060"). The results are shown in Table 1. 
Control 5 
A filtered cake of microfine globular colored particles was obtained by 
following the procedure of Example 19. When this filtered cake was heated 
and humidified for 20 minutes in an atmosphere kept at 85.degree. C. and a 
relative humidity of 60%, there were formed blocks which had the component 
particles thereof left virtually unfused. By drying the resultant mass of 
blocks at 50.degree. C., there were formed 1,500 parts of blocks. By 
coarsely crushing the blocks and feeding the coarse particles at a rate of 
20 kg/hr to the same device as used in Example 4 and disintegrating them 
therein, there was produced microfine colored particles (d) for 
comparison. By examination of a scanning electron micrograph of the 
microfine colored particles (d) for comparison, it was found that not less 
than 90% of the microfine colored particles (d) had spheric shapes, 
indicating total absence of any discernible effect of heating and 
humidifying treatments. 
The microfine colored particles (d) for comparison were tested for 
properties as a particulate substance. The microfine colored particles (d) 
for comparison were used as an electrophotographic toner (d) to produce 
images with an electrostatic copier (produced by Ricoh Co., Ltd. and 
marketed under product code of "Type 4060"). The results are shown in 
Table 1. 
Control 6 
A liquid containing aggregates of microfine spheric colored particles was 
obtained by the procedure of Example 27. This liquid was subjected to 
separation by filtration by the use of a continuous pressure filter. The 
resultant cake stopped on the filter was washed and, at the same time, 
heated by continuous addition thereto of 3,000 parts of hot water at 
135.degree. C., to form a mass of blocks of fused particles. By drying 
this mass at 50.degree. C., there were obtained 1,500 parts of blocks. By 
coarsely crushing the blocks, feeding the coarse particles at a rate of 2 
kg/hr to the same device as used in Example 27 and disintegrating them 
therein, to produce microfine colored particles (e) for comparison. 
The microfine colored particles (e) for comparison were tested for 
properties as a particulate substance. The microfine colored particles (e) 
for comparison were used in their unmodified forms as an 
electrophotographic toner (e) to produce images with an electrostatic 
copier (produced by Ricoh Co., Ltd. and marketed under product code of 
"Type 4060"). The results are shown in Table 1. 
Control 7 
A liquid containing aggregates of microfine globular colored particles was 
obtained by the procedure of Example 27. This liquid was subjected to 
separation by filtration by the use of a centrifuge. The cake consequently 
stopped on the centrifuge was washed and, at the same time, heated by 
continued addition thereto of 8,000 parts of hot water at 45.degree. C., 
to form blocks which had the component particles thereof left 
substantially unfused. By drying the mass of these blocks at 50.degree. 
C., there were obtained 1,500 parts of blocks. The blocks were coarsely 
crushed and then fed at a rate of 20 kg/hr to the same device as used in 
Example 27 and disintegrated therein, to produce microfine colored 
particles (f) for comparison. By the examination of a scanning electron 
micrograph of the microfine colored particles (f) for comparison, it was 
found that not less than 90% of the microfine colored particles had a 
globular shape, indicating total absence of any discernible effect of 
heating and humidifying treatments. 
The microfine colored particles (f) for comparison were tested for 
properties as a particulate substance. The microfine colored particles (f) 
for comparison were used in their unmodified forms as an 
electrophotographic toner (f) to produce images with an electrostatic 
copier (produced by Ricoh Co., Ltd. and marketed under product code of 
"Type 4060"). The results are shown in Table 1. 
Control 8 
A suspension (1') obtained by following the procedure of Example 16 was 
combined with 100 parts of an aqueous aluminum chloride solution 
containing 5% of a principal component to induce cohesion of the microfine 
globular colored particles. The resultant cake separated by filtration was 
dried, without subjecting to heat and humidify treatment to afford blocks 
possessing a bulk density of 0.23 g/cm.sup.3. The blocks were 
disintegrated by use of hammermill to produce microfine colored particles 
(g) for comparison. The microfine colored particles (g) were determined 
for triboelectricity. The results are shown in Table 2. 
TABLE 1 
__________________________________________________________________________ 
Evaluation of image production 
(Note 3) 
Attributes of Particles 
Environmental 
Environmental 
Amount (Note 2) Condition Condition 
Electro- disintegrated 
Coefficient 
Amount 23.degree. C. and 60% 
30.degree. C. and 90% 
RH 
photo- (pulverized) 
Particle 
of of tribo- Repeat- Repeat- 
graphic (kg/hr) 
diameter 
variation 
electricity 
Flow- 
Fog- 
ability of 
Clean- 
Fog- 
ability 
Clean- 
toner (Note 1) 
(.mu.m) 
(%) (.mu.C/g) 
ability 
ging 
fine line 
ability 
ging 
fine 
ability 
__________________________________________________________________________ 
Example 1 
(1) 15.0 5.67 18.7 -20.1 .circleincircle. 
none 
good fair 
none 
good fair 
Example 2 
(2) 12.0 6.15 23.0 -19.7 .circleincircle. 
none 
good fair 
none 
good fair 
Example 3 
(3) 18.0 5.24 19.8 -23.1 .circleincircle. 
none 
good fair 
none 
good fair 
Example 4 
(4) 17.0 6.14 20.8 -18.7 .circleincircle. 
none 
good fair 
none 
good fair 
Example 5 
(5) 13.0 5.65 21.2 -22.3 .circleincircle. 
none 
good fair 
none 
good fair 
Example 6 
(6) 18.0 6.10 22.0 -19.9 .circleincircle. 
none 
good fair 
none 
good fair 
Example 7 
(7) 15.0 5.65 20.7 -23.1 .circleincircle. 
none 
good fair 
none 
good fair 
Control 1 
Control 
4.0 6.22 18.3 -19.5 .largecircle. 
none 
fair fair 
seen 
bad fair 
(a) 
Control 3 
Control 
5 10.05 
14.3 -21.5 .largecircle. 
none 
bad fair 
none 
bad fair 
(b) 
Example 8 
(8) 16.0 5.78 17.5 -16.5 .circleincircle. 
none 
good fair 
none 
good fair 
Example 9 
(9) 20.0 5.81 17.1 -18.0 .circleincircle. 
none 
good fair 
none 
good fair 
Example 10 
(10) 13.0 6.35 19.0 -19.8 .circleincircle. 
none 
good fair 
none 
good fair 
Example 11 
(11) 20.0 5.24 19.8 -21.0 .circleincircle. 
none 
good fair 
none 
good fair 
Example 12 
(12) 18.0 6.20 20.0 -17.5 .circleincircle. 
none 
good fair 
none 
good fair 
Example 13 
(13) 13.0 5.73 20.5 -20.2 .circleincircle. 
none 
good fair 
none 
good fair 
Example 14 
(14) 19.5 6.21 21.5 18.5 .circleincircle. 
none 
good fair 
none 
good fair 
Example 15 
(15) 16.0 5.65 20.7 -17.5 .circleincircle. 
none 
good fair 
none 
good fair 
Example 16 
(16) 11 5.65 18.8 -20.2 .circleincircle. 
none 
good fair 
none 
good fair 
Example 17 
(17) 8 6.15 23.3 -19.6 .circleincircle. 
none 
good fair 
none 
good fair 
Example 18 
(18) 13 5.22 19.3 .circleincircle. 
none 
good fair 
none 
good fair 
Example 19 
(19) 15 6.24 20.8 -18.7 .circleincircle. 
none 
good fair 
none 
good fair 
Example 20 
(20) 10.5 5.67 21.5 -22.5 .circleincircle. 
none 
good fair 
none 
good fair 
Example 21 
(21) 9.5 6.15 22.5 -19.8 .circleincircle. 
none 
good fair 
none 
good fair 
Example 22 
(22) 7 5.65 21.7 -23.0 .circleincircle. 
none 
good fair 
none 
good fair 
Example 23 
(23) 10 5.64 18.7 -23.5 .circleincircle. 
none 
good fair 
none 
good fair 
Control 4 
Control 
2 6.22 18.3 -19.5 .largecircle. 
none 
fair fair 
seen 
bad fair 
(c) 
Control 5 
Control 
20 6.29 19.3 -15.0 .circleincircle. 
none 
fair bad seen 
bad bad 
(d) 
Example 24 
(24) 11 5.60 18.7 -20.2 .circleincircle. 
none 
good fair 
none 
good fair 
Example 25 
(25) 8 6.18 23.0 -19.6 .circleincircle. 
none 
good fair 
none 
good fair 
Example 26 
(26) 13 5.24 19.0 .circleincircle. 
none 
good fair 
none 
good fair 
Example 27 
(27) 15 6.23 20.5 -18.7 .circleincircle. 
none 
good fair 
none 
good fair 
Example 28 
(28) 10.5 5.65 21.6 -22.5 .circleincircle. 
none 
good fair 
none 
good fair 
Example 29 
(29) 9.5 6.12 22.3 -19.8 .circleincircle. 
none 
good fair 
none 
good fair 
Example 30 
(30) 7 5.61 21.5 -23.0 .circleincircle. 
none 
good fair 
none 
good fair 
Example 31 
(31) 12 5.45 12.8 -19.5 .circleincircle. 
none 
good fair 
none 
good fair 
Control 6 
Control 
2 6.22 18.3 -19.5 .largecircle. 
none 
fair fair 
seen 
bad fair 
(e) 
Control 7 
Control 
20 6.29 19.3 -15.0 .circleincircle. 
none 
fair bad seen 
bad bad 
(f) 
__________________________________________________________________________ 
(Note 1) Amount disintegrated (pulverized) The amount of a given sample 
fed to the ultrasonic jet pulverizing device (produced by Nippon Pneumati 
Kogyo K. K. and marketed under product code of "IDS2 Type") is reported 
herein as amount disintegrated (pulverized). 
(Note 2) Particle diameter: Measured with a Coulter Counter (produced by 
Coulter Electronics Inc and marketed under product code of "TAII Type"). 
Coefficient of variation: Measured with a Coulter Counter (produced by 
Coulter Electronics Inc and marketed under product code of "TAII"). 
Amount of triboelectricity: Measured of a mixture of a given sample with 
iron carrier (produced by Dowa Teppun K. K. and marketed under product 
code of "DSP128") with a blowoff powder charging tester (produced by 
Toshiba Chemical K. K. and marketed under product code of "Model TB200"). 
Flowability: The flowability of a given toner was visually evaluated on 
the fourpoint scale, wherein 
.circleincircle.: Complete independence and thorough flowability of 
individual toner particles. 
.largecircle.: Slight aggregation and ordinary flowability of individual 
toner particles. 
.DELTA.: Fair aggregation and inferior flowability of individual toner 
particles. 
X: Heavy aggregation and conspicuously poor flowability of individual 
toner particles. 
(Note 3) Evaluation of image production The ability of image production 
with an electrostatic copier was determined by copying a facsimile test 
chart No. 1 with a copier (produced by Ricoh Co., Ltd. and marketed under 
product code of "Type 4060" or produced by Canon Co., Ltd. and marketed 
under product code of "NP5000") using a given toner and evaluating the 
image consequently formed. 
Fogging This phenomenon was determined by the discrimination between the 
presence and the absence of the smearing of the ground with a given toner 
Repeatability of microfine line This property was determined by copying 
facsimile test chart No. 1 using a given toner and examining the 
legibility of the copied image. 
Cleanability This property was determined by copying a facsimile test 
chart No. 1 using a given toner and evaluating the copied image. 
TABLE 2 
______________________________________ 
Comparative 
Colored 
Colored colored 
particles 
particles 
particles 
(23') (31') (g) 
______________________________________ 
Environmental Condition 
-25.8 -21.8 -22.0 
23.degree. C. and 60% RH 
.mu.C/g .mu.C/g .mu.C/g 
Amount of 
triboelectricity 
Environmental Condition 
30.degree. C. and 90% RH 
-25.6 -20.9 -12.4 
Amount of .mu.C/g .mu.C/g .mu.C/g 
triboelectricity 
______________________________________