Plural color toners, developers comprising the same, image-forming method using the plural toners, and image-forming system therefor

The present invention relates to plural color toners for use in image-forming method of forming images cyclically with the toners, developers comprising the toners and image-forming method by use of the toners or developers and image-forming system therefor, and is characterized in that use is made of toners which have their surfaces in a substantially identical state.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to plural developers or toners each of which 
contains different materials, an image-forming method by use of them and 
an image-forming system therefor. 
Particularly, it relates to monocolor toners each of which contains 
different coloring agents, developers comprising these toners, a 
color-image forming method for forming color images by use of these toners 
or developers and a color image-forming system therefor. 
2. Description of the Prior Art 
Recently, as information for an office and a person are increasing, color 
copy is sought in the electrophotographic field. 
For example, sought are electrophotographic copying machine which can form 
exact full-color images from a manuscript, or copying machines, printers, 
facsimiles and the like of digital or analog type having multicolor 
function, business-color function and the like in order to provide such 
color images from the necessary parts as demanded by the operator. 
In these image-forming systems, a visible image is formed by 
electrophotography by use of plural monocolor developers or monocolor 
toners. Such developers and toners comprise for optimization of their 
performance various additives e.g. charge controlling agents (various 
dyes, metal complexes, etc.), magnetic powders and fluidity improvers 
(various oxides, nitrides, etc.). It goes without saying that in forming 
multi-color images, these developers or toners contain different coloring 
agents respectively or they are constituted of different binder resins 
respectively. 
When plural of toners or developers containing various materials are 
utilized in an image-forming process, optimal image-forming conditions are 
different from one toner or developer to the other, giving rise to 
troubles such as difficulty in control and unstable picture quality and so 
on. Further, variation in their image-forming performance under 
environmental fluctuation differs from one toner or developer to the 
other, resulting in image instability under varying environmental 
conditions, even after their performance is adjusted under a definite 
environment. Or even under identical environmental conditions, different 
corrections are required between individual toners or developers in the 
course of their continuous use because of the difference in durability 
from one toner or developer to the other. 
Recently known is a technique in which plural coloring agents are contained 
in a developer or toner. This developer or toner has difficulty to control 
because of different electrification performance from one coloring agent 
to the other or gives unstable picture quality. Such a trouble widely 
occurs notably in image-forming methods making use of plural/single 
toner(s) or developer(s) containing various coloring agents and the system 
used therefor. Even if a coloring agent is used in common, the other 
materials contained therein are different and the above trouble is brought 
about. When developers or toners containing a coloring agent in common are 
utilized in one system, the same trouble arises. For example, in the case 
of micro-reader/printer which makes use of 2 types of toners comprising a 
common coloring agent, charge controlling agents differs in 
electrification polarity for normal and reversal development. This poses 
the trouble to be resolved. 
Furthermore, when toners or developers containing various kind of materials 
are used in an image-forming process, the individual toners or developers 
undergo different variations from one to the other under different 
environmental conditions. When the variations in use are monitored, the 
individual toners or developers must be monitored. For example, when an 
image concentration is detected automatically in forming full color images 
(this system is referred to as AIDC), it becomes necessary to make 
detection for each toner of yellow, cyan, magenta and black. This leads 
not only to difficulty in control but rises in cost. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a developer, toner and 
image-forming method and the system used therefor in which the 
aforementioned inconveniences have been got rid of. 
Another object of this invention is to improve the performance of 
plural/single developer(s) or toner(s) containing various materials. 
A further object of this invention is to provide a method and a system 
which have large tolerances for the setting ranges of optimal 
image-forming conditions in the image-forming method and the system used 
therefore. 
A still another object of this invention is to provide a method and a 
system whose image-forming performance is insusceptible to change under 
fluctuating environmental conditions, when the image-forming method and 
the system used therefor utilize plural/single developer(s) and toner(s) 
containing plural materials. 
A still another object of this invention is to provide a method and a 
system whose image forming-performance is insusceptible to change in its 
continuous use, when the image-forming method and the system used therefor 
make use of plural/single developer(s) or toner(s) containing plural 
materials. 
A still another object of this invention is to provide an image-forming 
method and a system used therefor which permit easy monitoring of the 
image-forming situation in the image-forming method and the system used 
therefor which make use of plural/single developer(s) or toner(s) 
containing plural materials. 
The present inventors found out that the major factor responsible for the 
aforementioned inconvenience is the difference in the surface state of the 
developers or toners which gives rise to the difference in their 
electrification performance. 
Accordingly, it is the object of the present invention to provide 
developers or toners which have nearly identical surface properties, in 
particular, electrification characteristics. 
Therefore, it is the object of this invention to provide an image-forming 
method and the system used therefor which permit stable electrification 
performance to be continuously maintained by use of the said developers or 
toners. 
The above objects can be achieved by toners and developers having a common 
surface state. 
The present invention relates to plural color toners for use in 
image-forming method of forming images cyclically with the toners, 
developers comprising the toners and image-forming method by use of the 
toners or developers and image-forming system therefor, and is 
characterized in that use is made of toners which have their surfaces in a 
substantially identical state. 
When multiple types of developers or toners containing various kinds of 
materials are researched and developed or when an image-forming method and 
the system used therefor which make use of the toners and the developers 
are researched and developed, it has become possible to research and 
develop such the developers, the toners, the image-forming method and the 
system used therefor in a very short period of time.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention provides toners or developers containing the toners 
each of which undergo identical variations in the amount of 
electrification under varying environmental conditions and which give 
stable adhesion of respective color toners, the respective toners being of 
different colors and containing different coloring agents. 
This invention also provides toners which are capable of meeting in a short 
time the demand for toners which are adaptable for multi-item and small 
lot production and which can be mixed to produce any desired colors. 
Further it provides an image-forming method and the system used therefor 
which make use of plural the aforementioned toners. 
This invention can be achieved by substantially equalizing the states of 
exposed surfaces of respective color toners. Such a toner may be obtained 
by composing it as shown in FIG. 1. Thus the toner of this invention 
comprises at least a domain-resin composition 1, a matrix-resin 
composition 2 which is low in compatibility with the domain resin and a 
dispersing assistant 3 which is compatible with both the domain and matrix 
resins and which has a higher Izod impact value than that of the matrix 
resin, the domain-resin composition being dispersed in the matrix-resin 
composition with the dispersing assistant interposed therebetween. The 
reference number 4 shows a coloring agent. The reference number shows a 
charge controlling agent, added if desired. 
The dispersing assistant phase is covering at least part of the domain 
resin phase. Used as a dispersing assistant and the matrix resin are 
resins having definitely different impact resistances between them, 
whereby effective protection of the domain resin from breakage is assured 
in the pulverizing step. Therefore, the coloring agent is confined in the 
domain resin, without being exposed at the toner particle surfaces, to 
achieve stabilized electrification. Further, the existence of such a 
dispersing assistant deters overpulverizing, resulting in high producing 
efficiency. 
The matrix resins of the toners composing the electrophotographic 
developers of this invention include homo- or co-polymers of 
.alpha.-olefines (including ethylene) such as ethylene, propylene, 
butene-1, pentene-1, 4-methyl pentene-1 and hexane-1, block, random or 
graft copolymers of more than half by weight of these .alpha.-olefins with 
other unsaturated compounds, modified olefinic polymers which are formed 
from the above homo- or co-polymers by halogenation, sulfonation, 
oxidation and so forth, acrylonitrile-styrene copolymers (AS resin), 
polycarbonates, thermoplastic polyesters, polyamides, polystyrenes, 
styrene-butadiene-styrene block copolymers, polyacrylonitrile, polymethyl 
methacrylate and rubber and the like thermoplastic polymers. 
Said unsaturated compounds which are copolymerizable with the 
.alpha.-olefins are vinyl esters such as vinyl acetate and like, vinyl 
silanes such as vinyl trimethoxysilane and vinyl triethyoxysilane, and 
ethylenic unsaturated monomers other than the above-illustrated 
.alpha.-olefins. 
As the thermoplastic polymers used according to this invention, polyesters 
and polystyrenes are preferable for the matrix resin. 
The polyesters preferably used according to this invention are 
appropriately selected from among those obtained by polycondensation of 
typically used polybasic acids and polyhydric alcohols. 
The polybasic acids include aromatic carboxylic acids such as terephthalic 
acid, isophthalic acid and trimellitic acid, aliphatic carboxylic acids 
such as adipic acid, hexahydroterephthalic acid, succinic acid, 
n-dodecenyl succinic acid, isododecenyl succinic acid, n-dodecyl succinic 
acid, n-octyl succinic acid, isooctyl succinic acid and n-butyl succinic 
acid, unsaturated carboxylic acids such as maleic acid fumaric acid, and 
their anhydrides. The polyhydric alcohols include ethylene glycol, 
propylene glycol, 1,4-butanediol, hexamethylene glycol, neopentyl glycol, 
2,2,4,4-tetramethylene glycol, glycerine, trimethylol propane, bisphenol 
A, hydrogenated bisphenol A, sorbitol or their etherized hydroxyl 
compounds such as polyoxyethylene (10) sorbitol, polyoxypropylene (5) 
glycerine, polyoxyethylene (4) pentaerythritol, 
polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane and 
polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane. 
More preferable polyesters are those soluble in solvents. Those 
noncrystalline or slightly crystalline, particularly those having less 
than 5% crystallinity, as determined by X-ray analysis, have large effect. 
With regard to the softening point, those having 40.degree.-150.degree. 
C., particularly 60.degree.-150.degree. C., have large effect and with 
regard to the number average molecular weight (Mn), those having 
500-30000, particularly 1000-20000 have large effect. 
Polystyrenes preferably used according to this invention are polystyrene or 
those formed by copolymerizing with styrene any of unsaturated 
copolymerizable monomers e.g. unsaturated carboxylic acids such as acrylic 
acid and methacrylic acid, unsaturated carboxylates such as 
methylacrylate, ethyl acrylate, methyl methacrylate, n-butyl methacrylate, 
dibutyl fumarate and dioctyl fumarate, unsaturated carboxylic anhydrides 
such as maleic anhydride and itaconic anhydride, and derivatives thereof, 
in the range below half thereof. Among them those having 
30.degree.-105.degree. C. of glass transition points and 1000-150000 of 
Mn, particularly 2000-100000 of Mn, have large effect. 
As the polystyrenes used according to this invention, those soluble in 
solvents are especially preferable. 
Such a matrix resin should exist in an amount sufficient to substantially 
coat the dispersed domain-resin component. Thus they are usable in wide 
ranges in respective toners. In general it should preferably be used at 
20-99% by weight, more preferably 30-95% by weight, of the toner resin. If 
its amount is less than the aforementioned range, the matrix resin and the 
domain resin undergo phase reversal. As a result, the coloring 
agent-containing resin is exposed after pulverization, causing improper 
electrification and tending to overpulverizing. This results in spreading 
particle size distribution, improper dispersion and lowered manufacturing 
efficiency. Its amount in excess of the aforementioned range will invite 
improper dispersion of the coloring agent into the matrix resin. 
While similar resins as those of the aforementioned matrix resin may be 
applied to the domain resin. The domain resin, however, should be made not 
evenly compatible with the matrix resin by using comonomers to be 
copolymerized to change its compatibility with the matrix resin. In this 
way the domain resin can be dispersed in the matrix resin. 
The coloring agent used in the toner for the electrophotographic developer 
of this invention is dispersed in and held by the domain resin and this 
domain resin is dispersed in the matrix resin, whereby the exposure of the 
coloring agent at the toner surface is prevented. Thus the materials of 
the exposed surface can be made substantially identical to those of other 
toners even if the toners have different types of coloring agents. 
That is to say, in the toner composition of this invention, the matrix 
resin and the domain resin are not uniformly compatible with each other 
and the one having larger affinity for the coloring agent should serve as 
the domain resin. 
The dispersing assistant used in the toner of this invention is a copolymer 
containing the domain resin component and the matrix resin component. The 
one obtained by graft-copolymerizing a resin containing monomers which 
compose one of the domain or matrix resin with monomers composing the 
other resin is preferable. 
The dispersing assistant used according to this invention acts to finely 
disperse the domain resin into the matrix resin. Its 1% by weight or more, 
if present in the toner composition, will make the dispersion phase 
sufficiently fine and uniform. It should preferably be used at 3% by 
weight or more. 
The dispersing assistant used should have an Izod impact value of 0.1 
kgf.multidot.cm/cm.sup.2 or more, preferably 0.2 kgf.multidot.cm/cm.sup.2 
or more, more preferably 0.4 kgf.multidot.cm/cm.sup.2 or more higher than 
that of the matrix resin. By using such a resin, the matrix phase is 
preferentially broken in the pulverizing process, thereby preventing the 
breakage of the domain resin. Accordingly, the coloring agent is left 
confined in the domain resin phase, thereby making it possible to prevent 
exposure of the coloring agent at the toner surface. If its Izod impact 
value is smaller than the aforementioned range, the domain resin also 
tends to be stressed, thereby becoming vulnerable to breakage. Once the 
domain resin phase is broken, the coloring agent is exposed, making it 
impossible to make the materials of their exposed surfaces substantially 
identical between different toners. 
In connection with this invention, the Izod impact value is represented by 
the value obtained by measurement by use of a Mini-max Izod impact tester 
(Model CS-183; made by Instrument K.K.). In taking this measurement, a 
test piece of 30.times.12.times.2.0 [mm] is prepared by press molding 
(conditions: 130.degree. C., 60-70 kg/cm.sup.2) and this test piece is 
placed on the tester. 
Actual examples of the method for preparing the dispersing assistant by 
graft reaction of styrenic polymer with vinyl monomer include (1) a method 
of making the reaction with vinyl monomer added to a solution of the 
polymer dissolved in a solvent, (2) a method of making the reaction with 
the polymer dissolved in vinyl monomer, (3) a method of making the 
reaction, after suspending polymer particles in water and then adding 
vinyl monomer thereto, thereby to impregnate the polymer particles with 
it, (4) a method of making the reaction, with the polymer dissolved in 
vinyl monomer in the state of being floated as liquid drops in water, (5) 
a method of making the reaction of the polymer in melt state with vinyl 
monomer and (6) radiation-grafting method, etc. Among these methods, 
preferable methods are those of (3) or (4) mentioned above. In the polymer 
obtained by the method of (3) or (4), the matrix resin and the domain 
resin are simultaneously contained and formed, so that the product may be 
used without separately adding the matrix or domain resin. 
In performing this reaction, normally a polymerization initiator is used. 
As the polymerization initiator, generally those for use in radical 
polymerization may be used, but it is preferable to choose it from those 
having a decomposition temperature of 45.degree.-110.degree. C., 
particularly 50.degree.-105.degree. C., in view of the temperature of the 
polymerization reaction. The decomposition temperature means the 
temperature when the decomposition ratio of the radical generator is 50% 
after a solution added with 0.1 mole of the polymerization initiator in 1 
liter of benzene was left to stand for 10 hours. 
Such initiators that may be mentioned as practical examples include organic 
peroxides such as 2,4-dichloro-benzoyl peroxide (54.degree. C.) (the 
temperature in parenthesis designates the decomposition temperature), 
tert-butyl peroxypivalate (56.degree. C.), o-methyl benzoyl peroxide 
(57.degree. C.), bis-3,5,5-trimethyl hexanoyl peroxide (60.degree. C.), 
octanoyl peroxide (61.degree. C.), lauroyl peroxide (62.degree. C.), 
benzoyl peroxide (74.degree. C.), tert-butyl peroxy-2-ethyl hexanoate 
(74.degree. C.), 1,1-bis(tert-butyl peroxy)-3,5,5-trimethyl cyclohexane 
(91.degree. C.), cyclohexanone peroxide (97.degree. C.), 
2,5-dimethyl-2,5-dibenzoyl peroxyhexane (100.degree. C.), tert-butyl 
peroxybenzoate (104.degree. C.), di-tert-butyl-diperoxyphthalate 
(105.degree. C.), methyl ethyl ketone peroxide (109.degree. C.), dicumyl 
peroxide (117.degree. C.), dicumyl-tert-butyl peroxide. These compounds 
may be jointly used. 
The amount of the polymerization initiator to be used should fall in the 
range of 0.05-30% by weight, preferably 0.1-10% by weight, of vinyl 
monomer. 
According to this invention, the dispersing assistant may be obtained by 
graft-polymerizing in situ a monomer which can form the matrix resin (e.g. 
polyester) and a monomer (e.g. styrene) which can form the domain resin. 
Usable coloring agents to be contained in the toners are not particularly 
limited, but include well-known ones e.g. carbon black, azo dyes, titanium 
oxide and other various dyes and pigments. As substantial total amount of 
the coloring agent is dispersed and filled into the domain resin, the 
coloring agent to be used should have larger affinity for the domain resin 
than for the matrix resin. 
Generally in the electrophotographic copying system, there is employed a 
mechanism for automatically supplementing the amount of the toner that has 
decreased by a predetermined rate as the toner in the developing machine 
has been consumed. In the developing system for full color, there is 
employed a mechanism for supplementing the decreased amount of the toner 
upon detection of the toner concentration in the developing machine, 
taking advantage of the spectroscopic characteristic (reflection 
characteristic) to near infrared light of the coloring agent contained in 
the toner. In the case of a black toner containing carbon black as 
coloring agent, the carbon black absorbs nearly 100% of near infrared 
light. The black toner can not be detected using near infrared light. Thus 
the black toner containing the conventional carbon black can not be used 
as a black toner for full color. On this account, the black toner for use 
in the full color developing system should be composed of a mixture of 
three coloring agents of magenta, cyan and yellow which give spectroscopic 
characteristics to near infrared light. When a black color is produced by 
mixing the three coloring agents, it turns bluish black, if each coloring 
agent is not uniformly dispersed. As it is difficult to make uniform 
dispersion particularly by a melting and kneading method, it is difficult 
to achieve pure black. 
The toners used for electrophotography are prepared generally by kneading a 
coloring agent etc. with a matrix resin which serves as a binder, 
pulverizing the kneaded matter and classifying the pulverized matter to 
adjust their particle size distribution to specified one. 
The toner obtained by the pulverizing process in this way has the coloring 
agent nonuniformly exposed at its surface. The coloring agents, because of 
their low humidity and environmental resistance, raise problems in 
individual toners' uniformity and in their amount of electrification, and 
storage and environmental stability etc. Further, separation of coloring 
agent and its adhesion on the carrier surface cause unstable 
chargeability. 
In this connection this invention provides for the benefit of more 
preferable mode of its application a black toner for use of full color 
which contains the coloring agent with surface exposure restrained and 
which is excellent in electrification characteristic and stability 
(humidity, printing, environmental and storage resistance) and also in 
tint. 
Thus a more preferable black toner in the present invention is a black 
toner for use of full color which comprises a domain-resin composition 
containing a black coloring agent comprising in mixture respective 
coloring agents of at least yellow, cyan and magenta, a matrix-resin 
composition having low compatibility with the domain resin and a 
dispersing assistant which is compatible with both the domain resin and 
the matrix rein and which has an Izod impact value higher than that of the 
matrix resin, the domain-resin composition being dispersed in the 
matrix-resin composition, with the dispersing assistant interposed 
therebetween. 
This black toner is obtained by a production method comprising (a) a step 
of obtaining a kneaded matter prepared by melting and kneading the domain 
resin and a black coloring agent composed of in mixture at least yellow, 
cyan and magenta, (b) a step of obtaining a colored composition by melting 
and kneading the kneaded matter obtained by the step of (a), the matrix 
resin having low miscibility with the domain resin, and the dispersing 
assistant which is compatible with both the domain and matrix resins and 
which has an Izod impact value higher than that of the matrix resin, and 
(c) a step of pulverizing and classifying the kneaded matter obtained by 
the step of (b). 
In the constitution of the black toner for use of full color according to 
this invention, the coloring agent 4 in reference to FIG. 1 is a black 
coloring agent comprising in mixture at least yellow, cyan and magenta 
coloring agents. 
The black coloring agent for use in the more preferable black toner of this 
invention comprises in mixture at least yellow, cyan and magenta coloring 
agents. 
There are mentioned as yellow coloring agents, C.I. pigment yellow 12, C.I. 
pigment yellow 13 etc.; as magenta (red) coloring agents, C.I. pigment red 
122, C.I. pigment red 57:1 etc.; as cyan (blue) coloring agent, C.I. 
pigment blue 15 etc. But the usable coloring agents are not limited to 
them. Any of various color pigments and dyes conventionally used in 
transparent color toners are usable. 
The mixing proportion of the respective colors of yellow, magenta and cyan 
may be so selected as to give the desired black color. 
As for their mixing method, the coloring agents of yellow, magenta and cyan 
and the domain resin may be simultaneously mixed by a melting and kneading 
method. The domain resin may be mixed with the black coloring agent 
prepared in advance by mixing the respective coloring agents of yellow, 
magenta and cyan. 
The black coloring agent composed of respective yellow, magenta and cyan 
coloring agents in mixture is used in a range of 3-50% by weight, 
preferably 5-25% by weight of the toner finally obtained. If its amount is 
less than 3% by weight, adequate concentration is not obtained even with a 
large amount of the developer. If it is larger than 50% by weight, 
possibility of the domain being broken at the time of pulverizing the 
toner is high. Then the coloring agent will be exposed at the toner 
surface, causing improper electrification. Besides because of the small 
proportion of the matrix resin, its fixing performance is poor. 
Since it is necessary to disperse and fill the substantial total amount of 
the coloring agent into the domain resin, the coloring agent used should 
have larger affinity for the domain resin than for the matrix resin. 
To the toners composing the developers of this invention, may be further 
added low molecular weight olefinic polymers, colloidal silica, fatty 
acids and metal salts of fatty acids and the like for the purpose of 
modifying their fluidity, mold releasability and so on. 
For the toners of this invention, it is proper to select the component 
compositions according to their uses as one-component toners or as 
two-component developers which is used together with carriers. Basically 
they may be prepared through the undermentioned steps: 
(1) A step of obtaining a kneaded matter by melting and kneading the domain 
resin and the coloring agent. 
(2) A step of obtaining a kneaded matter by melting and kneading the matrix 
resin which has low compatibility with the domain resin with a charge 
controlling agent. 
(3) A step of obtaining a colored composition by melting and kneading the 
kneaded matter obtained by the step (1), the kneaded matter obtained by 
the step (2) and a dispersing assistant which is compatible with both the 
domain and matrix resins and which has an Izod impact value higher than 
the matrix resin, and 
(4) A process of pulverizing and classifying the kneaded matter obtained by 
the step (3). 
Since the impact resistance of the dispersing assistant phase is set higher 
than that of the matrix phase, possible breakage of the dispersing 
assistant phase and the domain resin phase in the pulverizing process, 
when producing the toner, is effectively prevented. Accordingly, breakage 
occurs in the matrix resin phase only, so that the surface of the 
pulverized matter or the surface of the toner obtained is substantially 
formed only of the matrix resin phase containing the charge controlling 
agent. This is because the substantial total amount of the coloring agent 
is contained in the domain resin phase and the stress of pulverization 
concentrates in the matrix phase, to have the matrix phase form the 
surface phase, so that the respective coloring agents in the domain phase 
will not be exposed at the surface. Accordingly, even if the type and 
color of the coloring agent are altered in many ways, toners with their 
exposed surfaces in a substantially identical state are obtainable. The 
particle diameter of the dispersed phase of the domain resin in the matrix 
resin should preferably be 5 .mu.m or smaller. The particle diameter 
herein mentioned means the average primary particle diameter (Martin's 
diameter) which is measured by observation of the section of the specimen 
by means of a microscope. 
Thus a toner of the present invention is usually obtained to have a mean 
particle diameter of 5-20 .mu.m, preferably 5-10 .mu.m. 
The present invention has as its principal objects attainment of high 
classified yield and stabilization of electrification through prevention 
of exposure of coloring agents with attention focused on the breakability 
of the toner, but its various characteristics may be controlled by 
appropriately adding other additives e.g. charge controlling agents, 
fluidizing agents etc. into the matrix or domain resin and such modes are 
also covered by this invention. 
The present invention will be particularly described in connection with its 
preferred embodiments, without however being limited thereto. 
Example 1 
The domain resin, matrix resin and the dispersing assistant used in this 
embodiment are listed as follows: 
Domain resin Styrene-acrylate copolymer 
MW: 53000 
Izod impact strength: 0.51 [kgf.multidot.cm/cm.sup.2 ] 
Matrix resin Styrene-maleic anhydride copolymer 
MW: 10000 
Izod impact strength: 0.17 [kgf.multidot.cm/cm.sup.2 ] 
Dispersing assistant Modified styrene polymer 
Izod impact strength: 0.41 [kgf.multidot.cm/cm.sup.2 ] 
Example of manufacture of dispersing assistant 
Four kg of water, 80 g of tribasic calcium phosphate and 0.12 g of sodium 
dodecyl benzene sulfonate were put in an autoclave of a 10-liter capacity 
to provide an aqueous medium, to which was added a solution of 8 g of 
NYPER B dissolved in a mixed solution of 640 g of styrene and 160 g of 
n-butyl acrylate, followed by stirring. Into this mixture, 1200 g of 
particles of the aforementioned matrix resin (styrene copolymer) were 
introduced. After replacing the atmosphere inside the autoclave with 
nitrogen, the inside-system temperature was raised to 60.degree. C. This 
temperature was maintained for 3 hr, thereby impregnating the styrene 
containing the aforementioned polymerization initiator into the matrix 
resin particles. Next 11.4 g of PERBUTYL PV was introduced into this 
suspension. Then the inside-system temperature was raised to 65.degree. C. 
and this temperature was maintained for 2 hr, thereby initiating the 
polymerization on the surfaces of the styrene polymer particles. 
Thereafter, the system-inside temperature was raised to 90.degree. C. and 
this temperature was maintained for 3 hr, to complete the polymerization. 
After cooled, the content was taken out, pickled and rinsed to give 2 kg of 
dispersing assistant resin. 
Forty-two parts by weight (hereinafter abbreviated to pbw) of the domain 
resin and 3 pbw of the coloring agent (Lionol Yellow FG-1310; made by Toyo 
Ink Seizo K.K.) were melt-kneaded in a twin extruder. 
Next 52 pbw of the matrix resin and 3 pbw of a charge controlling agent 
(Bontron E-81; made by Orient Kagaku K.K.) were melt and kneaded in a twin 
extruder. 
Then 45 pbw of the kneaded domain resin, 55 pbw of the kneaded matrix resin 
and 8 pbw of the dispersing assistant were melt and kneaded in a twin 
extruder to give a colored composition. 
Part of this colored composition was sandwiched between a slide glass and a 
cover glass and turned into a thin film by heat fusion on a hot press. As 
this film was observed under a transmission type optical microscope, 
existence of a colored dispersion phase was seen. The diameter of the 
dispersion phase ranges from 0.5-1.0 .mu.m. This dispersion phase was 
uniformly and finely dispersed in the matrix. The coloring agent was not 
seen in the matrix and the charge controlling agent existed only in the 
matrix. 
The colored matter thus obtained was finely pulverized by a jet mill and 
thereafter a yellow toner of 11 .mu.m average particle diameter was 
obtained by classification. 
Further magenta, cyan and black toners of 11 .mu.m average particle size 
were prepared by using coloring agent(s) set as below to be melt and 
kneaded with 42 pbw of the domain resin: 
______________________________________ 
Magenta toner 
Lionol Red 6B FG-4213 (made by Toyo Ink Seizo K.K.) 
3 pbw 
Cyan toner 
Lionol Blue FG-7350 (made by Toyo Ink Seizo K.K.) 
3 pbw 
Black toner 
Lionol Yellow FG-1310 (made by Toyo Ink Seizo K.K.) 
2 pbw 
Lionol Red 6B FG-4213 (made by Toyo Ink Seizo K.K.) 
2 pbw 
Lionol Blue FG-7350 (made by Toyo Ink Seizo K.K.) 
2 pbw 
______________________________________ 
As the respective colored compositions were observed by the above-mentioned 
method, existence of colored dispersion phase was likewise seen. In this 
dispersion phase, its dispersion had particle diameters ranging from 
0.5-1.0 .mu.m and was found to be uniformly and finely dispersed in the 
matrix. The coloring agent was not seen in the matrix and the charge 
controlling agent existed only in the matrix. 
The colored matters thus obtained were finely pulverized by a jet mill and 
then classified to give magenta, cyan and black toners respectively. Each 
toner was 11 .mu.m in average particle diameter. 
Comparative Example 1 
A colored matter was obtained by melting and kneading the listed materials 
below: Resin as a binder 
Styrene-maleic acid copolymer (same as the resin used as the matrix resin 
in the aforementioned example) 100 pbw 
______________________________________ 
Charge controlling agent 
Bontron E-81 (made by Orient Kagaku K.K.) 
3 pbw 
Coloring agent 
Lionol Yellow FG-1310 (made by Toyo Ink K.K.) 
3 pbw 
______________________________________ 
The colored matter thus obtained was finely pulverized by a jet mill and 
thereafter classified to give a yellow toner of 11 .mu.m average particle 
diameter. 
Further magenta, cyan and black toners 11 .mu.m average particle diameter 
were prepared by using coloring agent(s) set as below. 
______________________________________ 
Magenta toner 
Lionol Red 6B FG-4213 (made by Toyo Ink Seizo K.K.) 
3 pbw 
Lionol Blue FG-7350 (made by Toyo Ink Seizo K.K.) 
3 pbw 
Black toner 
Lionol Yellow FG-1310 (made by Toyo Ink Seizo K.K.) 
2 pbw 
Lionol Red 6B FG-4213 (made by Toyo Ink Seizo K.K.) 
2 pbw 
Lionol Blue FG-7350 (made by Toyo Ink Seizo K.K.) 
2 pbw 
______________________________________ 
Evaluation Measurement of amount of electrification in one-component 
system: 
Each of the 4 color toners of Example and Comparative Example i.e. yellow, 
magenta, cyan and black toners was put into a developing machine (its 
control blade was made of SUS) for one component system shown in FIG. 2, 
to measure the amount of its electrification in respective environmental 
conditions. 
In FIG. 2, toner particles are put in the space where a feed vane 10 
rotates. The toner particles are stirred by a feed vane 10 in the space. 
After stirred for a specified time, the toner particles are provided on a 
brush roller 9. The toner particles on the brush roller cover the surface 
of a sleeve 8. The toner particles on the surface are regulated to a thin 
layer by a control blade 7. 
The measurement was carried out by stirring the toner in the developing 
machine for 5 min after putting it thereinto, followed by blowing off the 
toner on the sleeve. The results are displayed in FIGS. 3 and 4. 
FIGS. 3 and 4 demonstrate that while the respective color toners of Example 
gave identical variations in the amount of electrification, respective 
color toners of Comparative Example gave different variations. This is 
believed to be due to the fact that whereas in the toners of Comparative 
Example, respectively different coloring agents are exposed at their 
surfaces, in the toners of Example of this invention, respective coloring 
agents are protected and coated with the identical resin. 
Measurement of amount of electrification in two-component system: 
Under respective environmental conditions, each of the four color toners of 
Example and Comparative Example and a ferrite carrier (F141-300; made by 
Powdertech K.K.) were put in a poly bottle made of polypropylene. This 
bottle was placed on a stirring stand and after its content was stirred 
for 5 min, the amount of its electrification was measured. The toner 
concentration was 6% and the measurement of the amount of electrification 
was taken by means of the blow-off method. The results are shown in FIGS. 
5 and 6. 
FIGS. 5 and 6 demonstrate that whereas the respective color toners of 
Example gave identical variations in the amount of electrification, the 
respective color toners of Comparative Example gave differing variations. 
The reason is presumed to be similar to that in the case of the 
one-component system. Confirmation by use of a full color copying machine 
CF-70 (made by Minolta Camera K.K.) 
Application of toners prepared in Example and Comparative Example to 
full-color copying machine CF-70 (made by Minolta Camera K.K.) 
In the following, some explanation is made on CF-70. It was somewhat 
modified for expediency in the experiment. 
FIG. 7 is a schematic sectional view of the mechanism sections of the 
digital color copying machine CF-70. 
This digital color copying machine is equipped with a color-image-reading 
section A located at the upper part, a color-printer section B placed at 
the intermediate part and a feeding unit C provided at the lower part. The 
color-image-reading section A reads the color images of the manuscript 
mounted on a manuscript mounting glass 26. CCD image sensor of contact 
type resolves color images into 3 colors of red (R), green (G) and blue 
(B) by a contact CCD image sensor, and then converts the read data into 
respective digital image signals for the three colors. The color printer B 
is an electrophotographic laser color printer. The printer reproduces the 
cyan (C), magenta (M), yellow (Y) and black (K) colors in this order at 
every scanning in accordance with the aforementioned digital image 
signals. Dot images, that are so-called digital images, are transferred to 
the copying paper fed from the feeding unit C plural number of times. This 
digital copying machine is provided with monocolor modes of forming 
monocolor images in 7 colors of C, M, Y, K and R, G and B. 
First the color-image-reading section A will be explained: 
A manuscript-scanning device 50 is provided with an exposure lamp 27 for 
irradiating the manuscript, a rod lens array 28 for condensing the light 
reflected from the manuscript and a CCD image sensor of contact type 29 
for converting the condensed reflected light into electric signals of R, G 
and B respectively. At the time of reading the manuscript image, the 
manuscript-scanning device 50 scans the manuscript on the manuscript 
mounting glass 26 in the sub-scanning direction Al. The manuscript image 
irradiated by the exposure lamp 27 is photoelectrically converted by the 
CCD image sensor of contact type 29. The respective R, G and B electrical 
image signals outputted from the CCD image sensor of contact type 29 are 
converted by an image processing unit 30 into a digital signal for either 
one of C, M, Y or K. The digital signal is in turn outputted to the print 
head part 31 of the color printer section B. 
Next the color printer section B will be described: 
The print head part 31 is provided with a digital/analog conversion 
(hereinafter abbreviated to D/A conversion) circuit for making D/A 
conversion of the print-driving digital signals outputted from the image 
processing unit 30, a laser diode for driving amplifier amplifying the 
print-driving signals which have been D/A converted, a laser diode LD 
which emits light in response to each of the print-driving signals, a 
polygon mirror (not shown) for scanning the laser beam emitted from the 
laser diode LD in the main scanning direction, a motor (not shown) for 
rotationally driving the polygon mirror and a f.theta. glass (not shown) 
for focussing the scanned laser beam on a photosensitive drum 4 through a 
reflection mirror 33. 
The laser beams emitted from the laser diode LD inside the print head part 
31 in response to the print-driving signals are scanned by the polygon 
mirror in the main scanning direction. Then after reflected by the 
reflection mirror 33, the laser beams reach onto a photosensitive drum 4. 
Electrostatic latent images corresponding to the manuscript images are 
formed on the photosensitive drum 4. Around the photosensitive drum 4, 
there are installed a charger 5 for uniformly charging the surface of the 
photosensitive drum 4 in the predetermined polarity, an eraser lamp 6 for 
eliminating electrical charges on the surface of the photosensitive drum, 
a developing system 20 for developing with use of toners the electrostatic 
latent images formed on the photosensitive drum 4 and a blade 7 for 
recovering the residual toner left untransferred to a transfer drum 8 from 
the photosensitive drum 4. The developing machine 20 has developing units 
20a, 20b, 20c and 20d each of which contains a developer comprising a 
mixture of one of the respective toners mentioned above, that is, magenta, 
cyan, yellow and black colored toners, with a carrier. Each developing 
unit is movable in vertical direction, as shown by the arrow A.sub.2. 
When, for example, the toner image of cyan is to be formed on the 
photosensitive drum 4, the developing unit 20b for cyan may be moved to 
the position where it is brought into touch with the photosensitive drum 
4, to perform the development with the cyan toner. It should be noted that 
this experimental machine is so composed as to make variable the applied 
voltage Vb of the developing electrode (sleeve). Development by use of 
magenta, yellow or black toner is similarly to be performed by moving each 
developing unit 20a, 20c or 20d for respective toners to the position 
where each unit comes in contact with the drum 4. 
This experimental machine is modified such that the mechanism can be 
stopped to detect an amount of the toner transferred on the photosensitive 
drum 4 when a toner image has been formed thereon. 
A transfer drum 8 for transferring the toner image formed on the 
photosensitive drum 4 to copying paper is installed below the 
photosensitive drum 4 and in contact therewith. Around the transfer drum 
8, there are installed charge-eliminating chargers 9a and 9b for 
eliminating electrical charges on the surface of the transfer drum 8, a 
transfer charger 10 for transferring the toner image formed on the 
photosensitive drum 4 to the transfer drum 8, an adsorption charger 11 for 
electrostatically adsorbing the copying paper onto the transfer drum 8, a 
press roller 12 for pressing the copying paper against the transfer drum 8 
at the time of the electrostatic adsorption, a reference-position sensor 
13 for detecting the predetermined reference position on the transfer drum 
8, a fur brush 14 for recovering the toner not transferred onto the 
copying paper from the transfer drum 8 and a separating pawl 51 for 
separating the copying paper from the transfer drum 8. The photosensitive 
drum 4 and the transfer drum 8 are, as shown in FIG. 7, rotationally 
driven respectively in the directions of arrows A.sub.3 and A.sub.4 and 
synchronized to each other. 
The feeding unit C is provided with three feeding trays 21a, 21b and 21c. 
The copying paper is fed from one of the feeding trays selected from among 
the feeding trays 21a, 21b and 21c. The copying paper is conveyed by 
conveying rollers 44, 43, 42, 41 and 40, thereafter chucked at its front 
end on the transfer drum 8 by dint of the feeding charger 11 and the press 
roller 12. After the toner image on the transfer drum 8 is transferred to 
the copying paper by the well-known method, the copying paper is separated 
from the transfer drum 8 by means of a separating pawl 51 and carried to 
the image fixing device 16 by a conveying belt 22. Then the copying paper 
on which the image has been completely fixed is discharged onto a 
discharge tray 24 by a discharge roller 45. 
In a copying machine is used in full color mode, the respective toner 
images are formed on the photosensitive drum 4 in the order of cyan, 
magenta, yellow and black. These toner images are superposed on the 
copying paper chucked on the transfer drum 8 one by one. Then the copying 
paper on which the four color images have been superposed is conveyed to 
the fixing device 16. 
In the monocolor mode, only single color of cyan, magenta, yellow or black 
respectively is transferred to the copying paper, then to be fixed in 
accordance with the predetermined mode. Or it includes the modes in which 
only yellow and magenta are superposed on the copying paper to be fixed as 
red (R), only cyan and yellow to have green (G) or only magenta and cyan 
for blue (B). 
To be sure, this invention will be effective not only in the full color 
mode but in all image modes, even such monocolor modes as mentioned above, 
in the case where plural of toners take part in producing any color. 
A confirmation experiment has been carried out, using the four colors of 
toners of the aforementioned example. The conditions therefor were set as 
follows: 
Developer: Two-component type 
Carrier: F141-300 (made by Powdertech K.K.) 
Toner concentration: 6%. 
Environmental conditions: H/H, N/N, L/L (high temp./high humidity, normal 
temp./normal humidity, low temp./low humidity) 
Image stabilizing method: The adhesion amount of the yellow toner on the 
photosensitive member is detected, to compare it with a standard one. With 
respect to the standard amount, the developing potential difference 
.DELTA.V was adjusted so as to make the maximal adhesion amount of the 
yellow toner on the paper constant at 0.8 mg/cm.sup.2 in any environmental 
conditions. In this machine, for which the reversal development is 
adopted, .DELTA.V was controlled by altering the developing electrode bias 
(Vb). 
The data of .DELTA.V obtained for the yellow toner was applied to the 
conditions for toners of other colors. The results are shown in FIG. 8. 
FIG. 8 clearly demonstrates that toners of respective colors gave quite 
stable adhesion amount under respective environmental conditions. From 
this it was confirmed that the toners of respective colors undergo equal 
variations in the amount of electrification under any environmental 
conditions. 
This results assures that when full color images are formed or when images 
are formed under any monocolor mode by use of any toners of this 
invention, copy images are obtainable which give no deviating adhesion 
amount in each color, but which are true to the images of the manuscript. 
Further toners of different colors containing different coloring agents 
show equal fluctuations in the amount of electrification. The adhesion 
amount of each color toner is stable. 
Example 2 
In developers of other forms, toner mixtures for desired colors may be 
obtained by mixing various color toners. For example, by mixing yellow and 
magenta toners, a mixed toner of red may be obtained; from yellow and cyan 
toners, green; and from magenta and cyan, blue. Further, a metallic toner 
may be mixed to give metallic tone. Besides, by mixing these toners in 
various proportions, mixed toners of desired colors may be obtained. 
The preferred embodiments will be particularly described: 
Yellow, magenta and cyan toners used in this embodiment are identical with 
those described in Example 1. Only the black toner is different from that 
of Example 1. 
The three color toners were taken respectively in the same proportion and 
put in a mixer to be mixed together, yielding a black toner for use of 
full color. 
This black toner was mixed with a carrier (F141-300; made by Powdertech 
K.K) to have 8% toner concentration. The developer of black was taken into 
the developing machine 20d in a full color copying machine CF-70 (made by 
Minolta Camera K.K.). Each developer of yellow, magenta or cyan was taken 
into the developing machines 20a, 20b and 20c in a manner similar to 
Example 1. 
The running test with this system was done with 15000 sheets of paper to 
form full color copy images based on color manuscript images. Fine fogless 
images could be maintained. 
Comparative Example 2 
A colored matter was obtained by melt and kneading the undermentioned 
materials: 
______________________________________ 
Resin for binder 
Styrene-maleic anhydride copolymer 
100 pbw 
(the same as the resin used as the matrix resin in 
the aforementioned Example) 
Charge controlling agent 
Bontron E-81 3 pbw 
(made by Orient Kagaku K.K.) 
Coloring agent 
Lionol Yellow FG-1310 3 pbw 
(made by Toyo Ink Seizo K.K.) 
______________________________________ 
The colored matter thus obtained was finely pulverized by a jet mill, 
followed by classification, to give a yellow toner having average particle 
diameter of 11 .mu.m. 
Then by use of the coloring agents below, magenta, cyan and black toners 
having average particle diameter of 11 .mu.m were obtained: 
______________________________________ 
Magenta toner 
Lionol Red 6B FC-4213 3 pbw 
(made by Toyo Ink Seizo K.K.) 
Cyan toner 
Lionol Blue G-7350 3 pbw 
(made by Toyo Ink Seizo K.K.) 
______________________________________ 
Since in the above three color toners, respective coloring agents are 
exposed at the toner surfaces, the materials appearing on the surfaces are 
different in each toner. 
A black toner for use of full color was obtained by putting the above three 
color toners into a mixer respectively in equal proportion. 
This toner was mixed with a carrier (F141-300; made by Powdertech K.K.) to 
have 8% toner concentration. The mixture was then charged into a full 
color copying machine CF-70 (made by Minolta Camera Co., Ltd.) similarly 
as in Example 2, to perform a running test. From the beginning heavy 
fogging occurred. It was impossible to put the developer into practical 
use. 
Example 3 (red toner) 
A red toner was obtained by taking the yellow and magenta toners obtained 
in Example 1 in equal proportion into a mixer and mixing them together. 
This toner was mixed with a carrier of binder type (made by Minolta Camera 
K.K.) to have toner concentration of 8%. Then the mixture was taken into a 
copying machine EP-5400 (made by Minolta Camera K.K.) to be subjected to a 
running test of 15000 sheets. Fogless fine image were kept. 
In the following, some explanation will be taken on FP5400: 
FIG. 9 is a schematic sectional view of a copying machine capable of making 
two-color copy simultaneously. The standard copying operation is explained 
to reproduce the manuscript image as it is by referring to FIG. 9. 
First in the state of a photosensitive drum 100 turning in the direction of 
an arrow (a), a definite electrical charge is given on the photosensitive 
drum 100 by the discharge of the electrification charger 101. 
Then while a scanner 104 having an exposure lamp 103 in an optical system 
102 is scanned in the direction of an arrow (b) to irradiate a manuscript 
mounted on a manuscript mounting glass 105. The surface of the 
photosensitive drum 100 is exposed to the reflected light at the exposing 
area W through mirrors and lenses, whereby a static latent image is formed 
thereon in correspondence with the manuscript image. This electrostatic 
latent image is turned into a visible image by the toner supplied at the 
developing region X or X' facing the following first developing unit 106 
or second developing unit 107, whereby a toner image reproducing the 
manuscript image is formed. 
Copying paper is selectively fed from a feeding unit 108 and conveyed to 
the part facing a transfer charger 110, with the timing adjusted to the 
toner image on the photosensitive drum 100 by means of a pair of timing 
rollers 109. The toner image is transferred to the copying paper. The 
copying paper is carried between a pair of fixing rollers 112 by 
transporting unit 111, where the toner image is melt to be fixed on the 
copying paper. The paper is then discharged to the delivery section 113. 
The first developing unit 106 and the second developing unit 107 are 
removable in the copying machine. They are exchangeable with developing 
units of the same type containing different colored developers. These 
developing units 106 and 107 are designed to be exchangeable with a black 
developing unit containing a developer comprising the black toner and a 
carrier, a red developing unit containing a developer comprising the 
aforementioned red toner and a carrier or other color developing units 
containing developers comprising each color toner and a carrier. 
In this example, the developing machine is so composed that its first unit 
is not operated and that its second unit only is operated. In Example 3, 
the black toner in the first developing unit is not particularly defined, 
but the toners in the first developing unit may be assumed to have their 
surfaces in the same state as the toner in the second developing unit. 
While in this example 3, a red toner is described, a blue toner may be 
obtained by mixing the magenta toner with the cyan toner obtained in 
Example 1, and a green toner by mixing cyan and yellow toners. 
Comparative Example 3 
The yellow and magenta toners obtained in Comparative Example 2 were taken 
in the same proportion into a mixer to give a red toner. 
This toner was mixed with a binder carrier (made by Minolta Camera K.K.) to 
have toner concentration of 8%. Then a running test was done with this 
developer charged into a copying machine EP-5400 (made by Minolta Camera 
K.K.) similarly as in Example 3. Its practical use was impossible because 
heavy fogs are formed from the beginning. 
Example 4 (Metallic Blue Toner) 
Forty two pbw of the domain resin prepared in Example 1 and 3 pbw of Pearl 
pigment (Iriodin 100 Silver Pearl; made by Merck K.K. ) were melt and 
kneaded in a twin extruder. 
Next 52 pbw of the matrix resin prepared in Example 1 and 3 pbw of a charge 
controlling agent (Bontron E-81; made by Orient Kagaku K.K.) were melt and 
kneaded in a twin extruder. 
Then 45 pbw of the kneaded domain resin, 55 pbw of the kneaded matrix resin 
and 8 pbw of a dispersing assistant were melt and kneaded in a twin 
extruder to give a metallic composition. 
Part of this metallic composition was sandwiched between a slide glass and 
a cover glass and turned into a thin film by heat fusion on a hot press. 
As this film was observed under an optical microscope of transmission 
type, existence of a dispersion phase colored with a metallic tone was 
observed. The dispersion phase had particle diameters ranging from 40-80 
.mu.m and was uniformly and finely dispersed in the matrix. The Pearl 
pigment was not found in the matrix and the charge controlling agent was 
present only in the matrix. 
The obtained metallic composition in this way was finely pulverized by a 
jet mill and then classified, to give a metallic toner having average 
particle diameter of 100 .mu.m. 
The magenta and cyan toners prepared in Example 1 and the metallic toner 
were put into a mixer in a proportion of 1:1:2, to be mixed together, 
giving a metallic blue toner. 
The toner thus obtained was mixed with a carrier of binder type (made by 
Minolta Camera K.K.) to have toner concentration of 8%. This mixture was 
put into a copying machine EP-5400 (made by Minolta Camera K.K.). The 
running test of 150000 sheets was done similarly as in Example 3. A fine 
fogless image was maintained. 
While in this example, a metallic blue toner was described, a metallic 
green toner may be obtained by mixing the cyan and yellow toners prepared 
in Example 1 with the metallic toner, and a metallic red toner by mixing 
the yellow and magenta toners with the metallic toner. 
Comparative Example 4 
A metallic composition was obtained by melting and kneading the materials 
below: 
______________________________________ 
Resin as a binder 
Styrene/maleic anhydride copolymer 
100 pbw 
(the same resin as the matrix resin in the above 
example) 
Charge controlling agent 
Bontron E-81 (made by Orient Kagaku K.K.) 
3 pbw 
Coloring agent 
Iriodin 100 Silver Pearl (made by Merck K.K.) 
3 pbw 
______________________________________ 
The metallic composition then obtained was finely pulverized by a jet mill, 
followed by classification to give a metallic toner having average 
particle diameter 11 .mu.m. 
A metallic blue toner was obtained by putting the magenta and cyan toners 
prepared in Example 1 and the aforementioned metallic toner into a mixer 
in a proportion of 1: 1: 2. 
The toner thus obtained was mixed with a binder carrier (made by Minolta 
Camera K.K.), to have toner concentration of 8%. Then a running test of 
15000 sheets was performed with this mixture put into a copying machine 
EP-5400 (made by Minolta Camera K.K.) similarly as in Example 3. Heavy 
fogging occurred from the beginning. The metallic blue toner can not taken 
into practical use. 
Example 5 
In the following, black toners preferable according to this invention are 
illustrated. 
The same domain and matrix resins and dispersing assistant as employed in 
Example 1 were used. 
Fifty pbw of the domain resin, 3 pbw of an organic pigment Lionol Yellow 
FG-1310 (made by Toyo Ink Seizo K.K.), 6 pbw of another organic pigment 
Lionol Red 6B FG-4213 (made by Toyo Ink Seizo K.K.) and 6 pbw of an 
further organic pigment Lionol Blue FG-7350 (Toyo Ink Seizo K.K.) were 
melt and kneaded in a twin extruder. 
Sixty pbw of this kneaded material, 40 pbw of the matrix resin and 8 pbw of 
the dispersing assistant were melt and kneaded to give a colored 
composition. 
Part of this colored composition was sandwiched between a slide glass and a 
cover glass, to turn it into a thin film through its heat fusion on a hot 
press. Observation of this film under an optical microscope of 
transmission type revealed that a colored dispersion phase is present with 
its particle diameters ranging from 0.5-1.0 .mu.m and that this dispersion 
phase was uniformly and finely dispersed in the matrix. No coloring agent 
was seen in the matrix. 
The colored matter thus obtained was finely pulverized by a jet mill, 
followed by classification, to give a toner having average particle 
diameter of 11 .mu.m. Its classified yield at this time was 91%. 
Example 6 
A colored composition was obtained similarly as in Example 5, except that 
use was made of 90 pbw of a kneaded matter which was obtained by melting 
and kneading in a twin extruder 50 pbw of the domain resin, 8 pbw of an 
organic pigment Lionol Yellow FG-1310 (made by Toyo Ink Seizo K.K.), 16 
pbw of another organic pigment Lionol Red 6B FC-4213 (made by Toyo Ink 
Seizo K.K.) and 16 pbw of a further organic pigment Lionol Blue FG-7350 
(made by Toyo Ink Seizo K.K.). 
As this composition was evaluated in the similar way, it turned out to be 
in the same dispersed state as that of Example 1. Further the classified 
yield was 87%, which was equal to that in Example 1. 
Further 1.0% by weight of hydrophobic titanium (T805; made by Nihon Aerosil 
K.K.) and 0.2% by weight of hydrophobic silica (H2000/4) were added to 
each toner of Examples 5 and 6 to be mixed in a Henschel mixer. This 
mixture and a ferrite carrier (F141-300; made by Powdertech K.K.) were 
mixed in a proportion of 8:92, to give a developer. Then its amount of 
electrification was measured. 
The amount of electrification of each toner was measured by a blow-off 
electrification measuring instrument. Its amount of electrification after 
leaving it under high temperature (30.degree. C.) and high humidity (85% 
RH) for 12 hr and that after leaving it at 45.degree. C. for 1 month were 
measured. 
The results are summarized in Table 1. 
TABLE 1 
______________________________________ 
Characteristics of respective toners 
Electrification performance 
Initial After After 
amount of leaving at leaving at 
Electric electrifi- 
30.degree. C., 85% 
45.degree. C., for 
resistance cation for 12 hr 1 month 
______________________________________ 
Example 
More than -20 .mu.c/g 
-19 .mu.c/g 
-19 .mu.c/g 
5 10.sup.15 
Example 
10.sup.15 -19 -18 -16 
______________________________________ 
Similarly as in Example 1, the developers prepared as described hereinabove 
were put in a full color copying machine (CF-70; made by Minolta Camera 
K.K.) to be subjected to a durability test of 7000 sheet. 
The toners of Examples 5 and 6 showed no tendency of forming fogs on the 
ground and gave a degree of blackness which was quite high and which had 
no bluish tint. 
The black toner for use of full color is excellent in environmental 
stability in its electrification characteristic, printing resistance and 
keeping stability.