Mono-component developer, method of forming image and method of forming multi-color image

The present invention provides a mono-component developer comprising toner particles containing a binding resin, a colorant and an additive and a method of forming images by use thereof. In the present invention said additive is preferably a titanium compound prepared by through the reaction between TiO(OH).sub.2 and a silane compound or through the reaction between TiO(OH).sub.2 and a silicone oil. The specific gravity of the said titanium compound is in the range of 2.8 to 3.6. The average particle diameter thereof is in the range of 10 to 70 nm. The said toner particle is preferably a non-magnetic particle. By making use of the mono-component developer and the method for forming an image using it, charging of the toner, and carriage of the toner can be stabilized over a long period of time, and stable image formation can be obtained.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is related to a mono-component developer and a method for 
forming an image, more particularly, it is related to a mono-component 
developer and a method for forming a (multicolor) image comprising the 
steps of: forming a thin layer of the developer on a developer-holding 
member by making use of said mono-component developer, carrying said thin 
layer to a developing region, and developing an electrostatic latent image 
on a latent image-holding member. 
2. Description of the Related Art 
In recent years, an electrophotographic dry developing process has been 
used in not only an electrostatic copying apparatus, but also in a 
printer, facsimile and copying apparatus as well as combined apparatus of 
copying apparatus with facsimile. It has been recently required that these 
apparatuses are formed in lighter and smaller sizes and satisfy ecological 
requirements such as economy in energy, recycling, etc. In order to 
satisfy these requirements, an improvement and development have been 
extended in a method of forming an image and developer used therefore. As 
a dry development process in an electrostatic copying system practically 
used at the present are known two kinds of development, one is two 
component development making use of toner and carrier such as iron powder 
etc. and the other is mono-component development which dose not use a 
carrier. 
The two-component development is the most widely utilized process. This 
process, however, suffers from the defect that it can not maintain long 
term image quality because of deterioration of developer. The toner 
particles adhere to the surface of the carrier. This process also has a 
disadvantage in that large developing apparatus is necessary, since it 
requires a control system for toner concentration to keep the 
concentration of the toner in the developer constant and a mixing 
apparatus for mixing the newly added toner with the developer. Therefore, 
the demand for a mono-component development system which is able to make 
the developing apparatus light and small has increased. 
The mono-component toner development system is classified into two types of 
processes, one is a magnetic mono-component development system using 
magnetic toner, and the other is a non-magnetic mono-component development 
system using non-magnetic toner. In the magnetic mono-component 
development system, the magnetic toner is retained by making use of a 
developer-holding member such as a magnet etc. equipped with a means for 
generating a magnetic field therein and development is carried out. The 
magnetic mono-component development possesses several advantages that the 
toner may be easily carried and controlled and internal adhesion of 
copying apparatus, printer, etc. is minimal. However, the magnetic toner 
used in the magnetic mono-component development suffers from a serious 
disadvantage in that it cannot be full-colored because it contains black 
or brown magnetite and the like therein. Further, there are limits to how 
much the magnetic mono-component developing apparatus can be reduced in 
size because the developing roll must include a magnet therein, and 
therefore, a developing roll of a certain size is required. 
On the other hand, colorization may be feasible in a non-magnetic 
mono-component development system because a magnetic substance is not used 
in the toner. And since no magnet is used in the developer-holding member, 
reductions in weight and size, cost-saving, etc. are feasible. In recent 
years, the non-magnetic mono-component development system has been, 
accordingly, undertaken to be practically utilized as a small-sized 
full-color printer. 
However, in the non-magnetic mono-component development system, the toner 
must be supplied and held stably on the developer-holding member and 
charged and developed by means of only static electric force due to the 
absence of stable charging and carrying means. While, the two-component 
development system contains a stable charging and carrying material as 
carrier, the magnetic mono-component development system has a magnetic 
force of a magnetic roll as stable charging and carrying means. Therefore, 
the non-magnetic mono-component development system is significantly 
inferior to the two-component development system or magnetic 
mono-component development system in maintaining high image quality over a 
long period of time. Particularly, in full-color copying apparatus and/or 
printers using four color developments of yellow, magenta, cyan and black, 
accurate control of developing amount is required and the toner should 
have strict performances such as speedy and uniform charge, good fluidity, 
etc. in order to cope with the miniaturization/speeding up of recent 
years. 
In recent years, instead of corona discharge a method for applying voltage 
to the surface of a photosensitive material in contact with a charging 
material directly or via a recording material or while pressing the 
surface of said photosensitive material directly by the charging material 
or via the recording material to charge and transfer in direct as a means 
for charging uniformly the surface of the photosensitive material 
(electrostatic charged image-holding member) or for transferring a toner 
image on said photosensitive material as described in, for example, 
Japanese Patent Application Laid-Open (JP-A) Nos. 63-149669 and 02-123385 
has been growing in popularity. The method for charging and transferring 
is superior to conventional corona discharge, since no ozone is produced 
and environmental resistance properties are excellent. In this method, the 
shear in transfer is reduced, since the surface of the photosensitive 
sheet holding an image is in contact with a transfer sheet(paper). 
Furthermore, the mono-component developing apparatus, especially the 
non-magnetic mono-component developing apparatus has the advantage of 
adapting well to shortening of the path for carrying the transfer sheet 
and to reduction of the diameter of the photosensitive material which 
result from miniaturization of image-forming apparatus required by the 
mono-component developing apparatus or non-magnetic mono-component 
developing apparatus. 
However, this apparatus also has disadvantages. The transfer apparatus must 
have pressurization to a certain extent during the transfer step. The 
toner image formed on the electrostatic latent image-holding member is 
also effected by this pressurization and agglomeration tends to occur, so 
that a phenomenon of inhibition of migration of the toner to transfer 
material is seen. This phenomenon is particularly significant in a linear 
portion in the range of 0.1 to 2.5 mm. The inventors of the present 
invention inferred that a good deal of toner is applied to the liner 
portion due to the edge effect and that agglomeration occurs through 
pressure. The toner image (transfer image) formed at this time has the 
serious defect of being formed only in profile, the so called "hollow 
character". In this way, the mono-component developing apparatus, 
especially the non-magnetic mono-component developing apparatus requires a 
toner exhibiting prevention of "hollow character". 
In order to stabilize the charging and carriage of the toner, a charge 
controlling agent is conventionally added. Typical examples of negative 
charge controlling agents may include metal-containing azo dyes, and 
metal-containing salicylic acid compounds. Typical examples of positive 
charge controlling agent may include quaternary ammonium salts etc. An 
addition of such charge controlling agents is effective and indispensable 
in the maintenance of speedy and uniform charging of toner over a long 
period of time. However, such charge controlling agents may fail to exert 
fully their effects due to the presence of additives used in combination 
therewith, especially externally supplied additives of fine particles for 
imparting fluidity. 
For example, inorganic fine powders like, for example, silica etc. are 
added to toners. However, this method can not make the carriage of the 
toner to the developer-holding member and chargeability of the toner 
optimum at either high temperature and high humidity or at low temperature 
and low humidity, and has disadvantages in that poor reproducibility of 
image density, background fogging, dripping of the toner, and internal 
adhesion of the apparatus, etc. occur. 
In order to reduce such disadvantages, use of surface treated inorganic 
fine powder has been proposed. For example, in JP-A Nos. 46-5782, 
48-47345, 48-47346, 59-34539, 59-198470, 59-231550, etc. is described a 
hydrophobic treatment of silica fine particles. However, these inorganic 
fine particles can not exert satisfactory effects, especially in 
chargeability. In the case of using a polyester resin as the binding 
resin, absolutely no effect was obtained. Further, the above problem of 
the hollow character occurred in the contact-transfer system. 
A method for treating the surface of the inorganic fine particle with 
silicone oil is proposed as described in, for example, JP-A Nos. 
61-249059, 61-277964, etc. as a method for increasing the hydrophobic 
nature of the inorganic fine particle. It is known that a significant 
effect can be obtained through this method because of the low surface 
tension peculiar to silicone oil and because of the lowering of 
non-electrostatic adhesion between toners, and especially because of the 
lowering of toner agglomeration under pressure. 
However, this conventional method exerts significant effects on the hollow 
character, but dose not solve the above problem of chargeability 
(environmental dependency). As a method of relaxation of the negative 
chargeability of the toner particles, a method of external addition of 
silica fine particles surface-treated with an amino-denatured silicone oil 
(JP-A No. 64-73354) and a method of external addition of silica fine 
particles surface-treated with aminosilane and/or amino-denatured silicone 
oil have been proposed (JP-A No. 1-237561). These methods could not, 
however, solve the environmental dependency problem. 
Further, the non-magnetic mono-component toner should, as above described, 
supply and hold stably the toner on the developer-holding member by only 
electrostatic force and should be charged and developed. Therefore, the 
non-magnetic mono-component toner must be charged by friction of contact 
with the developer-holding member (sleeve) and the charging blade for a 
short time and in a small space. Therefore, the toner must be charged 
quickly. However, the toner to which the silica fine particles are 
externally added can not usually be charged quickly with edge, whether 
with a two-component toner or a magnetic mono-component toner. The 
non-magnetic mono-component toner has the disadvantages of reverse pole 
fogging and toner clouding (internal adhesion of the apparatus) tending to 
occur easily at the low temperature and low humidity at which high charge 
can be obtained. 
As above stated, even if the silica fine particles are subjected to 
hydrophobic treatment, treatment for relaxation of negative chargeability, 
etc. the environmental dependency of the charge, charging speed and lack 
of charge distribution can not be improved with only the silica fine 
particles. 
Titania can be chosen as an inorganic oxide added for the purposes of 
charge and fluidity. The titania usually used can be charged more quickly 
than silica and may presumably make the charging distribution sharp 
through its low resistance. However, in case where titania is added high 
charge can not be given to the toner and a lowering of the amount carried, 
lowering of reproducibility of density caused by a lowering of charge and 
fogging of background tend to occur more easily. 
In order to improve this chargeability, whether in two-component or 
mono-component systems, is proposed a method for externally adding to the 
toner a hydrophobic titanium oxide obtained by treating the surface 
thereof with a silane compound, a silane coupling agent, and a silicone 
oil, etc. (JP-A Nos. 58-216252, 60-123862, 60-238847). Using this 
conventional method, the charging level of mono-component toner can be 
improved to a certain extent depending on the types and amounts of 
treating agents used. Particularly when a treatment is carried out with 
silicone oil, no phenomenon of hollow character occurs in the 
contact-transfer system. However, neither charging level nor environmental 
dependency can be improved satisfactorily. 
Improvements in charging level and environmental dependency can be seen by 
increasing the hydrophobic property of the titanium oxide with a 
processing agent. However, this titanium oxide is significantly inferior 
to conventional titanium oxide with regard to its charging speed, 
sharpness of charging distribution, etc. after the hydrophobic treatment. 
The crystals of titanium oxide can be obtained by sulfuric acid method or 
hydrochloric acid method from an ilmeniteore. However, when using these 
methods, chemical bonds formed by dehydration-condensation are naturally 
present in the crystal obtained. It was not easy to redisperse such 
agglomerated particles. Using conventional techniques this is because the 
derived titanium oxide forms secondary and tertiary agglomerations. The 
fluidity increasing effect of the toner was also significantly inferior to 
that of silica. On the other hand, the titanium oxide conventionally used 
has a specific gravity larger than that of silica and has a disadvantage 
in that it can not tightly adhere to the surface of the toner. It is 
easily removed from the surface of the toner. Therefore, the titanium 
oxide is inferior to silica with regard to the charge stability over a 
long period of time resulting from sleeve adhesion. Titanium oxide also 
tends to cause adhesion of photosensitive bodies, and thus deterioration 
of and defects in image quality. 
In order to achieve compatibility of fluidity improvement with 
environmental dependency of charging is attempted an addition of 
hydrophobic titanium oxide in combination with hydrophobic silica (JP-A 
No. 60-136755). While the defects of each hydrophobic titanium oxide and 
hydrophobic silica may be temporarily depressed by this method, they are 
much more subject to the influence of the other additive depending upon 
the state of dispersion. It is difficult to control stably the defects of 
each hydrophobic titanium oxide and hydrophobic silica over a long period 
of time. 
A method is proposed for adding hydrophobic amorphous titanium oxide 
obtained by hydrolysis to the toner (JP-A Nos. 5-204183 and 5-72797). 
However, while titanium oxide can improve both charging performance and 
fluidity of toner, much water is absorbed and contained in the particles, 
which remains in the photosensitive material at the time of transfer. That 
is to say, since adhesion between the amorphous titanium oxide and the 
photosensitive material is strong, only the amorphous remains on the 
photosensitive material without being transferred. This causes white spots 
on images or the photosensitive material is damaged by hard titanium oxide 
at the time of cleaning. 
On the other hand, in a method for purifying the titanium oxide by wet 
process, a method is proposed for hydrolyzing a silane compound in an 
aqueous medium, treating the surface of the titanium oxide, taking out the 
titanium oxide in a state of depressed agglomeration and adding the 
titanium oxide thus obtained to the toner (JP-A No. 5-188633). 
The titanium oxide obtained by this method can improve the fluidity of the 
toner more than the titanium oxide obtained by conventional hydrophobic 
process can, however, it does not satisfy high negative chargeability and 
environmental dependency. It also adversely affects the charging speed 
(admixing property of additional toner) and charging distribution. 
When these inorganic oxides are added to the surface of the toner, a 
filming or fusing of toner to the layer forming material occurs because of 
the stress applied to the toner from the layer forming material etc. by 
continuous use over a long period of time, or a change in the toner 
chargeability occurs by removal or embedding of additives externally 
supplied. Thus, this conventional method can not maintain stable charging 
and carriage of the toner over a long period of time easily. In order to 
solve these problem, is proposed a use of a specific binding resin for 
prevention of embedding of the additives externally supplied in, for 
example, JP-A Nos. 6-95429, 6-102699, 6-266156, etc. And a use of specific 
charging-controlling agent and external additives is proposed in JP-A Nos. 
6-51561, 6-208242, 6-250442, etc. However, these methods do not exert 
sufficient effects. Particularly, in a full-color development system in 
which four colors are superinposed upon each other, the amount of 
developing toner development must be controlled very accurately. 
Therefore, there still remain unsolved problems with regard to the 
charging amount and long term-stabilization of carriage amount of the 
toner. 
At present, the methods for forming an image adopted in a full-color 
copying apparatus or printer making use of electrophotographic systems, 
are exemplified by a-1) a system in which four developing apparatuses are 
arranged around the photosensitive material and steps of charging, 
exposure and development are repeated with respect to each toner in four 
cycles, and a-2) a system in which the charging, exposure and development 
of four color toner are carried out in one cycle, as well as a-3) a system 
in which four apparatuses of each charging apparatus, exposure apparatus, 
developing apparatus and transfer apparatus are disposed in one single 
apparatus and the toner images are superimposed. 
As the system in which four color toners are superinposed are exemplified 
by b-1) a system in which a toner image formed on the photosensitive 
material is transferred and superimposed color by color onto a transfer 
drum around which transfer paper is wound, b-2) a system in which a toner 
image formed on the photosensitive material are transferred to an 
intermediate transfer sheet, and color toner images are superimposed on to 
the transfer sheet and then transferred collectively to the transfer 
sheet, and b-3) a system in which color toner images are superinposed on 
to the photosensitive material, and then transferred collectively to the 
transfer sheet. 
While these methods have advantages and disadvantages in printing speed, 
apparatus size, etc., they are at present utilized according to the 
objects of the users. 
The above systems b-2) and b-3) have the following advantages; (1) system 
b-2) has good transfer paper carrying properties; and (2) system b-3) is 
capable of being reduced in size because use of an intermediate sheet is 
unnecessary. However, these two methods have the disadvantage that 
transfer of toner images formed on the bottom layer of the transfer paper 
is difficult because the toner images ultimately transferred to the 
transfer paper become multilayered. 
The full-color development has problems in common that the chargeability of 
the toner varies over repeated use, and thus the tone of the image 
changes. However, there has been no method for forming multicolor images 
able to simultaneously satisfy the problems. 
In order to improve the transferring property of the above superimposed 
toner image in addition to stabilizing the above charging amount, it is 
necessary that a reduction in adhesion between the toner and the 
photosensitive material and a reduction in adhesion between the toner and 
intermediate transfer sheet are made. 
SUMMARY OF THE INVENTION 
The object of the present invention is to solve the above problems. 
The object of the present invention is to provide a mono-component 
developer having stabilized charging and carriage of the toner over a long 
period of time and giving a stabilized image density. 
Further, the object of the present invention is to provide a mono-component 
developer which demonstrates few defects such as low developing property, 
fogging, etc., when employed over a long period of time. 
Further, the object of the present invention is to provide a mono-component 
developer which demonstrates few defects such as filming, fusing, etc., 
over a long period of time. 
The present invention achieves these objects through a non-magnetic 
mono-component developer. 
Further, the object of the present invention is to provide a method for 
forming an image by making use of the above mono-component developer. 
Particularly, the object of the present invention is to provide a method 
for forming an image which causes few problems involving hollow character, 
wherein the means of transferring toner images of the photosensitive 
material is not corona discharge, but the application of voltage to the 
surface of the photosensitive material to transfer while being in contact 
with the photosensitive material with a charging material in direct 
contact or through the recording material or while pressing the 
photosensitive material by the charging material in direct contact or 
through the recording material. 
The inventors of the present invention discovered the fact that a 
stabilized image with few problems such as change in density, fogging, 
filming, etc., can be obtained over a long period of time by using a 
mono-component developer comprising toner particles containing a binding 
resin, and a colorant and optionally a charge controlling agent and an 
additive, wherein said additive is a titanium compound obtained by a 
reaction of TiO(OH).sub.2 with silicone oil or a reaction of TiO(OH).sub.2 
with a silane compound. The mono-component developer may be preferably a 
non-magnetic mono-component developer. And the charge controlling agent 
may preferably contain a salicylic acid metal complex compound. 
The inventors of the present invention discovered also the fact that a 
method for forming an image comprising a step of forming a latent image on 
the latent image-holding member, a step of developing the said latent 
image by making use of the developer on the developer-holding member, and 
a step of transferring the toner image on the transfer sheet, wherein said 
developer is a mono-component developer, especially a method for forming 
an image by making use of contact-transfer system can provide an excellent 
image without hollow character. 
Since the mono-component developer, especially non-magnetic mono-component 
developer of the present invention fulfills all of the performances 
required of the mono-component developer such as chargeability, charging 
speed, low environmental dependency, charging distribution, ability to 
maintain the charge of the toner on the developer-holding member, low 
internal adhesion of the sleeve, few flaws and low adhesion of 
photosensitive material, etc., excellent image quality showing little 
change in image density, low developing property, low fogging, and defects 
in image quality, etc. over long periods of time can be obtained. Further, 
the mono-component developer of the present invention can provide an 
excellent image quality free of hollow character. 
Further, the object of another aspect of the present invention is to 
provide a method for forming a multicolor image, which is able to transfer 
accurately a superimposed toner image on a paper. 
And further, the object of another aspect of the present invention is to 
provide a method for forming a multicolor image, which is able to 
stabilize the toner charge over a long period of time and to provide 
stabilized image density. 
The inventors of the present invention discovered the fact that a 
stabilized image without defects such as change in image density, fogging, 
etc., can be obtained over a long period of time and a transferring 
property for transferring a superimposed toner image on a transfer sheet 
can be improved by using a method for forming an image comprising a step 
for developing repeatedly a latent image formed on the latent 
image-holding member by making use of plural developers and a step for 
transferring a multicolor toner image superimposed on said latent 
image-holding member or intermediate transfer sheet collectively on a 
transfer sheet, wherein said developer is a developer comprising at least 
a toner particle containing a binding resin and a colorant and an 
additive, and said additive being a titanium compound obtained through a 
reaction of TiO(OH).sub.2 with a silane compound or a reaction of 
TiO(OH).sub.2 with silicone oil, and silica having a BET specific surface 
area of between 20 and 100 m.sup.2 /g. 
Since the method for forming a multicolor image according to another aspect 
of the present invention satisfies all of the characteristics required for 
a multicolor forming process such as the transferring property of 
superimposed toner images, chargeability, charging speed, low 
environmental dependency, low adhesion of photosensitive material, etc., 
an excellent image can be obtained which demonstrates little change in 
image density over a long period of time, low developing property, 
fogging, and few defects in image quality, etc.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention is described below more in detail. 
The non-magnetic mono-component developer of the present invention is used 
in a method for forming an image comprising a step of forming a latent 
image on a latent image-holding member, and a step of developing said 
latent image by making use of a developer on a developer-holding member. 
The non-magnetic mono-component developer of the present invention is used 
particularly preferably in an apparatus for forming an image comprising a 
step of transferring a toner image formed on the latent image-holding 
member to a transfer sheet, and a step of heat-fixing the toner image on 
the transfer sheet in addition to the latent image forming step and the 
developing step. More preferably, the non-magnetic mono-component 
developer is used in a full color developing apparatus using four color 
toners of yellow, magenta, cyan and black. 
The conventional latent image forming step may be used for the present 
invention. For example, a electrostatic latent image is formed on the 
latent image-holding member such as photosensitive layer or dielectric 
layer, etc., by means of electrophotographic process or electrostatic 
recording process. The example of the latent image forming step may 
include a process of charging in non-contact by means of corona 
discharging device or a process of charging in contact with a charging 
material. The conventional photosensitive layer of the latent 
image-holding member may be used in the present invention such as organic 
type, amorphous silicon, etc. A cylindrical supporting member for holding 
the photosensitive layer may be obtained by the conventional producing 
method comprising extruding aluminum or aluminum alloy to mold and then 
surface-processing. 
In the developing step, a toner is formed in a state of thin layer on a 
rotating cylindrical drum as a toner-holding member(developing roller) by 
means of elastic blade etc. and carried to development region. The 
developing roller and latent image-holding member for holding the latent 
image are arranged in the development region in contact with each other or 
in a definite closed space between them and an electrostatic latent image 
is developed by a toner under applying bias between the developing roller 
and the latent image-holding member. In case of the non-magnetic 
mono-component developer, a rotary drum containing a magnet therein used a 
toner-holding member. 
The toner-holding member used in the present invention may include an 
elastic sleeve such as silicone, a sleeve formed by extruding ceramics or 
metals such as aluminum, SUS, nickel, etc., and those the surfaces of 
which are oxidized, metal-plated, ground, brushed, or coated with resin in 
order to control the carriageability of toner or chargeability. In 
particularly, if using the sleeve formed by extruding ceramics on metals 
such as aluminum, SUS, nickel, etc., the present invention may exert 
significant effects. The formation of the toner layer on the developing 
roller may be carried out by contacting the elastic blade with the surface 
of the sleeve. As the material of the elastic blade may be preferably used 
a rubber elastomer such as silicone rubber, urethane rubber, etc., and may 
be added and dispersed in the elastomer an organic or inorganic substance 
in order to control the charging amount of the toner. 
The method for developing four color toners may include a-1) a system in 
which developing apparatuses of four colors are arranged around the 
photosensitive material and steps of charging/exposure of the 
photosensitive material and development of the electrostatic latent image 
are repeated with respect to each color toner in four cycles; a-2) a 
system in which the charging/exposure/development of four color toner is 
carried out in one cycle; and a-3) a system in which developing 
apparatuses of four toners are arranged to four photosensitive materials 
and the charging/exposure/development of four color toner are carried out 
in each photosensitive material and developing apparatus. 
The method for superposing four color toner may include b-1) a system in 
which the toner image formed on the photosensitive materials is 
transferred and superinposed one color by one color onto the transfer drum 
around which a transfer paper is wound; b-2) a system in which the toner 
image formed on the photosensitive materials is transferred on the 
transfer sheet, and the color toner images are superimposed onto the 
transfer sheet, and then transferred collectively on the transfer sheet; 
and b-3) a system in which the color toner images are superinposed onto 
the photosensitive material and then transferred collectively onto the 
transfer paper. 
Preferably, the method for forming a multicolor image according to the 
third aspect of the present invention makes use of the system a-1) and 
b-2) or b-3). 
In the transferring step, the toner image formed on the latent 
image-holding member is transferred onto the transfer paper as transfer 
sheet. The method for forming a multicolor image according to the third 
aspect of the present invention comprises a collective transfer step of 
b-2) or b-3) as described above. The transferring means of the present 
invention may include conventional ones such as a contact type in which a 
transfer roller or transfer belt/drum is pressurized to contact with the 
latent image-holding member, a non-contact type using a corotron. The 
means of contact type is generally used for miniaturization of the 
apparatus. The present invention can exert its effect particularly in 
those of contact type, that is, those in which paper as transfer sheet is 
put between the latent image-holding member and the charging material is 
directly subject to contact/press and transferred. 
In the cleaning step, the toner is removed, which remains in the latent 
image-holding member without being transferred in the transfer step. The 
cleaning means may include conventional one such as blade cleaning, roller 
cleaning, etc. An elastic rubber such as silicone rubber, urethane rubber, 
etc. may be used as the blade cleaning. 
In the fixing step, the toner image transferred on the transfer sheet is 
fixed by means of a fixing apparatus. A heat roll is generally used as the 
heat-fixing means. 
The developer used in the present invention comprises toner particles 
containing a binding resin and a colorant as well as optionally a charge 
controlling agent and an additive. The charge controlling agent is 
preferably a salicylic acid metal complex compound. The additive contains 
a titanium compound obtained by a reaction of TiO(OH).sub.2 with silane 
compound or by a reaction of TiO(OH).sub.2 with silicone oil. The additive 
preferably contains hydrophobic silica fine particles. The TiO(OH).sub.2 
is produced by wet process, and the specific gravity of the titanium 
compound is preferably in the range of 2.8 to 3.6. When the specific 
gravity of the titanium compound is less than 2.8, while the elimination 
of titanium compound from the surface of toner decreases, the treatments 
tends to come away from the titanium compound because of increased 
reactions of the treatments themselves, the charging hindrance of the 
toner tends to easily occur because of filming on the photosensitive 
material or adhesion on the sleeve. When the specific gravity of the 
titanium compound is more than 3.6, the titanium compound itself tends to 
come away from the toner and the adhesion of the photosensitive material 
tends to easily occur, while the reaction of treatments themselves hardly 
occur and the treatments do not come away from the titanium compound. 
In general, the method for producing titanium oxide by normal wet process 
is carried out through a chemical reaction in a solvent, and may be 
classified in two processes; one is sulfuric acid process, and another is 
hydrochloric acid process. 
The sulfuric acid process is described briefly. The following reaction 
proceeds in a liquid phase, and insoluble TiO(OH).sub.2 is produced by 
hydrolysis. 
EQU FeTiO.sub.3 +2H.sub.2 SO.sub.4 .fwdarw.FeSO.sub.4 +TiOSO.sub.4 +2H.sub.2 O 
EQU TiOSO.sub.4 +2H.sub.2 O.fwdarw.TiO(OH).sub.2 +H.sub.2 SO.sub.4 
In the hydrochloric acid wet process, titanium tetrachloride is produced by 
chlorination according to analogous procedure to the dry process. Then, it 
is dissolved in water and hydrolyzed under an addition of strong base to 
produce Tio(OH).sub.2. The reaction formula is illustrated below; 
EQU TiCl.sub.4 +H.sub.2 O.fwdarw.TiOCl.sub.2 +2HCl 
EQU TiOCl.sub.2 +2H.sub.2 O.fwdarw.TiO(OH).sub.2 +2HCl 
The titanium compound used in the present invention may be produced by 
reacting the TiO(OH).sub.2 prepared in the wet process as described above 
with a silane compound or silicone oil, and drying. Since no calcination 
process at several temperatures is performed in the manufacturing process, 
a strong bonding of Ti--Ti is not formed and an agglomeration does not 
absolutely occur, and thus the particles may be taken out approximately in 
a state of primary particle. Further, since the titanium compound used in 
the present invention is produced by reacting directly TiO(OH).sub.2 with 
a silane compound or silicone oil, the amount treated thereby may be 
increased. While the titanium oxide conventionally treated had a low 
threshold value for treating amount contributing to the charging 
performance, the titanium compound used in the present invention has a 
high threshold value and can exert an effect on the treatment at about 
three times (about 50 to 70% on the basis of original titanium) in 
comparison with the conventional one. Therefore, the treating amount of 
silane compound can control the charge of the toner and can improve 
significantly the charging performance in comparison with the conventional 
titanium oxide. Further, since an excess silane compound is minimized and 
the reaction of silane compounds themselves is also decreased, high charge 
may be obtained without deterioration on charging speed and charging 
distribution in case of increasing treated amount. Further, the titanium 
compound used in the present invention migrates scarcely to the sleeve and 
the treatments do not also migrate therefrom, and thus the toner charge on 
the developer-carrier does not change over a long period of time because 
of little adhesion on the sleeve. Further, an adhesion on the 
photosensitive material does not absolutely occur and the defects in image 
quality do not also occur over a long period of time. This is because the 
titanium oxide used in the present invention do not come away from the 
surface of the toner for long-term use due to its strong adhesion to the 
surface of the toner because of the specific gravity of titanium oxide 
used in the present invention in the range of 2.8 to 3.6, which is lighter 
than conventional titanium oxide so that the migration of the treatments 
occurs scarcely, which is resulted from slight reaction of the silane 
compounds themselves to be treated(tightly bound to original body). 
Further, the titanium compound used in the present invention migrates 
scarcely to the sleeve and the treatments do not also migrate therefrom, 
and thus the toner charge on the developer-carrier does not change over a 
long period of time because of little adhesion on the sleeve. Further, an 
adhesion of toner to the photosensitive material does not absolutely occur 
and the defects in image quality do not also occur over a long period of 
time. This is presumably because the titanium oxide used in the present 
invention adheres tightly to the surface of the toner due to the specific 
gravity of titanium oxide used in the present invention in the range of 
2.8 to 3.6, which is lighter than conventional titanium oxide. 
Further, the titanium compound used in the present invention does not cause 
a phenomenon of hollow character even when a contact-transfer system is 
adopted. This is presumably because of low surface energy of silicone oil 
which is a treatment for titanium compound. That is, this is presumably 
because an agglomeration of toner itself does not occur due to low surface 
energy of the silicone oil even when the stress by pressure-contact is 
applied at the time of contact-transfer. 
In the present invention, the titanium compound having a resistance of 
between 10.sup.8 and 10.sup.12 .OMEGA..multidot.cm is used to control the 
charging distribution for prevention of fogging and improvement of 
developing property. When the resistance is less than 10.sup.8 
.OMEGA..multidot.cm, the chargeability of the toner decreases and thus the 
fogging and flying of toner tend to occur. On the other hand, when the 
resistance is more than 10.sup.12 .OMEGA..multidot.cm, the charging 
distribution of the toner becomes broad and the toner having two layers 
tends to easily occur because of the fogging by reverse polar toners and 
an adhesion of highly charged toner to the developer-holding member. 
The average primary particle diameter of the titanium compound used in the 
present invention is less than 100 nm, preferably in the range of 10 to 70 
nm. When the average primary particle diameter is more than 100 nm, a 
satisfactory fluidity can not be imparted to the toner, and the titanium 
compound tends to come away from the toner, which causes easily filming or 
comet to the photosensitive material. On the other hand, when the average 
primary particle diameter is less than 10 nm, an agglomeration of particle 
becomes remarkably intensified and a dispersibility to the surface of the 
toner is deteriorated. As a result, satisfactory chargeability and 
fluidity can not be obtained. A shortening of the particle diameter of the 
toner makes an adhesive force increase, and thus a failure of transfer may 
occur. In order to prevent such the failure of transfer, a silica or 
titania having large particle diameter is used as second external additive 
(transfer auxiliary), which may be available also in the present 
invention. When using such the titania of large particle diameter in the 
mono-component developer of the present invention, a good transferring 
property may be obtained without low charge, environmental dependency and 
lowering of admixing property (broadening of charging distribution for 
long run) resulted from second external additive. Also, lowering of charge 
imparting property at long term stress resulted from coming away of the 
treatments. In order to improve a failure upon transferring when the 
superimposed toner images are transferred collectively to a final transfer 
sheet, a silica having BET specific surface area of between 20 and 100 
m.sup.2 /g may be used in combination with the titanium compound to make a 
compatibility of the stability of charging with transferring property 
possible. 
The silane compound used in the present invention may include any types of 
silane compounds, for example, chlorosilane, alkoxysilane, silazane, 
specialty silylating agent. Specific examples thereof may include, but not 
limit to, methyltrichlorosilane, dimethyldichlorosilane, 
trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, 
tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, 
phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, 
methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, 
diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, 
hexamethyldisilazane, N,O-(bistrimethylsilyl)acetamide, 
N,N-(trimethylsilyl)urea, tert-butyldimethylchlorosilane, 
vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 
.gamma.-methacryloxypropyltrimethoxysilane, 
.beta.-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 
.gamma.-glycidoxypropyltrimethoxysilane, 
.gamma.-glycidoxypropylmethyldiethoxysilane 
.gamma.-mercaptopropyltrimethoxysilane, 
.gamma.-chloropropyltrimethoxysilane. 
Although the amount of the silane compound varies depending on the primary 
particle diameter of original material of TiO(OH).sub.2, the amount of the 
silane compound is, in general, in the range of 5 to 80 parts by weight, 
preferably in the range of 10 to 50 parts by weight based on 100 parts by 
weight of the original material of TiO(OH).sub.2. When the amount is less 
than 5 parts by weight, the silane compound to be treated can not exert 
its function. When the amount is more than 80 parts by weight, the 
titanium compound becomes oily because of excess silane compound, and thus 
the fluidity of the toner begins to become worse. The amount of the silane 
compound should be properly adjusted depending on kinds of toner to be 
used, developer-holding member, particle diameter of the original material 
of TiO(OH).sub.2, etc., in order to impart the high charge to the toner, 
to improve the environmental dependency, to increase the fluidity of the 
toner, to reduce the interaction of photosensitive material, and to 
prevent hollow character in the contact-transfer system. 
The titanium compound used in the present invention may be obtained by the 
reaction of TiO(OH).sub.2, especially TiO(OH).sub.2 prepared by wet 
process with a silicone oil or silicone varnish. 
As the silicone oil used in the present invention may be preferable those 
illustrated by the following general formula; 
##STR1## 
(wherein R is an alkyl group having 1 to 3 carbon atoms; R' is alkyl 
group, halogen-modified alkyl group, phenyl group, or modified phenyl 
group; R" is an alkyl group or alkoxy group having 1 to 3 carbon atoms; 
and m and n are integer.) 
These silicone oils may include, but not limited to, dimethylsilicone oil, 
methylhydrogensilicone oil, methylphenylsilicone oil, alkyl-modified 
silicone oil, .alpha.-methylsulfon-modified silicone oil, 
chlorophenylsilicone oil, amino-modified silicone oil, epoxy-modified 
silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone 
oil, methacryl-modified silicone oil, mercapto-modified silicone oil, 
phenol-modified silicone oil, polyether-modified silicone oil, 
methylstyryl-modified silicone oil, higher fatty acid-modified silicone 
oil, fluorine-modified silicone oil, etc. 
Although the treated amount of the silicone oil varies depending on the 
primary particle diameter of original material of TiO(OH).sub.2, the 
amount of silicone oil is, in general, in the range of 5 to 80 parts by 
weight, preferably in the range of 10 to 50 parts by weight based on 100 
parts by weight of the original material of TiO(OH).sub.2. When the amount 
is less than 5 parts by weight, the silicone oil to be treated can not 
exert its function. When such the amount is more than 80 parts by weight, 
the titanium compound becomes oily because of excess silicone oil, and 
thus the fluidity of the toner begins to become worse. The amount should 
be properly adjusted depending on kinds of toner to be used, 
developer-holding member, particle diameter of the original material of 
TiO(OH).sub.2, and the like, in order to impart the high charge to the 
toner, to improve the environmental dependency, to increase the fluidity 
of the toner, to reduce the interaction of photosensitive material, and to 
prevent hollow character in the contact-transfer system. 
The treatment procedure of the silicone oil to TiO(OH).sub.2 may be carried 
out by mixing silicone oil with a dispersion of TiO(OH).sub.2 or by mixing 
s solution or suspension of silicone oil with an organic solvent in a 
dispersion of TiO(OH).sub.2 to react each other. Then, the reaction 
product is filtered and dried to obtain desired product. 
Although the amount of additive (titanium compound) to be added to the 
toner varies depending on the particle diameter, such as composition of 
the developer-holding member and the like, it is in the range of 0.1 to 
5.0 parts by weight, preferably in the range of 0.2 to 2.0 parts by weight 
based on 100 parts by weight of the toner. When the amount of additive is 
less than 0.1 parts by weight, the fluidity of the toner can not be 
obtained. When the amount of additive is more than 5.0 parts by weight, a 
rise or lowering in fixing temperature may be resulted at the fixing step, 
and simultaneously a color developing property of superinposed under-layer 
may be hindered because of lowering of light transmission properties. 
In the present invention, another fine particles may be used as fluidizing 
agent in addition to the titanium compound in combination therewith for 
the purpose of assistance to proper fluidity and chargeability of the 
developer. The fine particle used as fluidizing agent may include 
inorganic fine particles such as silica, alumina, and the like; organic 
fine particles such as fatty acid or derivatives thereof and metal salts 
thereof; and resin fine particles such as fluororesin, acrylic resin and 
styrene resin. Most preferably, it may be silica fine particles. The 
surface of the silica fine particles used in the present invention may be 
treated with silane coupling agent or silicone oil to be hydrophobic, in 
order to improve chargeability and environmental stability. The silica 
treated with silicone oil may be preferable in terms of the environmental 
stability, agglomeration property of the toner and low adhesion of the 
toner to the photosensitive material. 
BET specific surface area of the hydrophobic silica to be used is in the 
range of 20 to 300 m.sup.2 /g, preferably in the range of 30 to 200 
m.sup.2 /g, more preferably in the range of 40 to 120 m.sup.2 /g. When BET 
specific surface area is less than 20 m.sup.2 /g, the hydrophobic silica 
tends to be easily dissolved from the surface of the toner, and filming or 
comet of the photosensitive materials also tends to occur, while an 
agglomeration becomes too worse to be fully dispersed on the surface of 
the toner when it is more 300 m.sup.2 /g. 
When the silica is used in the multicolor image forming process comprising 
a collective-transfer step according to the third aspect of the present 
invention, BET specific surface area of the silica is preferably in the 
range of 20 to 100 m.sup.2 /g. A variety of surface treated silica within 
the range may be used since the following disadvantage tend to occur in 
the multicolor image forming process comprising a collective-transfer 
step; when BET specific surface area is less than 20 m/g, a lacking in 
uniformity of image tends to occur because of decreased fluidity of the 
toner, while when it is more than 100 m.sup.2 /g, a transfer failure tends 
to occur in the toner, especially in the toner of the bottom layer. In 
this case, the amount of silica to be added to the toner is in the range 
of 0.1 to 5.0 parts by weight, preferably in the range of 0.2 to 2.0 parts 
by weight based on 100 parts by weight of the toner. When the amount is 
less than 0.1 parts by weight, the effect on the improvement of the 
transfer failure is not sufficient, while when more than 5.0 parts by 
weight, the lacking in unevenness of image tends to occur because of 
decreased fluidity of the toner. 
In the multicolor image forming process comprising a collective-transfer 
step according to the third aspect of the present invention, the ratio of 
the titanium compound to the silica is preferably in the range of 1:10 to 
10:1. When the ratio is out of range, there may be a tendency that the 
developing property and transferring property can not be satisfactorily 
improved at the same time. 
These fine particles are preferably used in the range of 0.1 to 3 parts by 
weight, more preferably in the range of 0.3 to 1.5 parts by weight based 
on 100 parts by weight of the toner. When the amount is less than 0.1 
parts by weight, a sufficient effect can not be imparted because of 
decreased surface coating of the toner by the fine particle. On the other 
hand, when the amount is more than 3 parts by weight, a comet or filming 
tends to easily occur because of adhesion of the fine particle to the 
photosensitive material. Furthermore, an environmental stability becomes 
worse. 
In the present invention, the toner particle used in the present invention 
may be essentially a conventional one comprising a binding resin and a 
colorant. Specific examples of the binding resin used include a 
monopolymer or copolymer of styrenes such as styrene, chlorostyrene, etc.; 
monoolefins such as ethylene, propylene, butylene, isoprene, etc.; 
vinylesters such as vinylacetate, vinylpropionate, vinylbenzoate, 
vinylbutyrate, etc.; .alpha.-methylene aliphatic monocarboxylic acid 
esters such as methylacrylate, ethylacrylate, butylacrylate, 
dodecylacrylate, octylacrylate, phenylacrylate, methylmethacrylate, 
ethylmethacrylate, butylmethacrylate, dodecylmethacrylate, etc.; 
vinylethers such as vinylmethylether, vinylethylether, vinylbutylether, 
etc.; or vinylketones such as vinylmethylketone, vinylhexylketone, 
vinylisopropenylketone, etc. 
The typical binding resin may include polystyrene, styrene-alkylacrylate 
copolymer, styrene-alkylmethacrylate copolymer, styrene-acrylic nitril 
copolymer, styrene-butadiene copolymer, styrene-maleic anhydride 
copolymer, polyethylene, polypropylene, etc. Further, the typical binding 
resin may include polyester, polyurethane, epoxy resin, silicone resin, 
polyamide, modified rosin, paraffin wax, etc. Polyesters are preferable in 
terms of color development/image intensity, more preferably, polyester 
resins having a softening point of 90-120.degree. C., preferably of 
95-115.degree. C. in terms of charging/keeping property of forming layer 
in the non-magnetic mono-component development. 
The term "softening point" as used herein means the temperature at the melt 
viscosity 10.sup.4 Pas (10.sup.5 poises) measured by a flow tester 
(manufactured by SHIMAZU SEISAKUSHO Co.Ltd., nozzle of 1.times.1 mm, 
load=10 kg). Although a color development becomes more better because of 
decreased fixing temperature and surface evenness of fixed image at the 
softening point below 90.degree. C., problems of offset to a heatroll at 
high temperatures or the decreased image intensity tend to easily arise 
and problems of lines or charging failure also tend to easily arise when 
repeatedly using because of the adhesion of the toner to the 
developer-carrier or layer forming blade. Although an adhesion of the 
toner to the developer-carrier or layer forming blade scarcely occurs and 
thus the development keeping property may be stabilized at the softening 
point of above 120.degree. C., a color development or OHP light 
transmission property comes into question because of deterioration of 
fixing property at low temperatures. 
Polyester resins having the glass transition temperature (Tg) of between 
60.degree. C. and 75.degree. C., preferably 62 and 70.degree. C. may be 
used in terms of an improvement of development keeping property to prevent 
adhering of the toner to the development-holding member or layer forming 
blade together with fixing property, blocking property and improved image. 
The glass transition temperature as used herein may be obtained from the 
Shoulder value in DSC curve measured by means of a differential scanning 
type calorimeter DSC-50 (manufactured by SHIMAZU SEISAKUSHO Co. Ltd., 
temperature-rising speed=10.degree. C./min., standard substance=alumina). 
When the Tg of the polyester is less than 60.degree. C., the blocking 
occurs and the storability lowers, while the fixing property lowers at Tg 
above 70.degree. C. 
The composition of the polyester resins in the present invention may be 
usually used a conventional monomer composition. The examples of an acid 
component may include phthalic acid, terephthalic acid, isophthalic acid, 
fumaric acid, maleic acid, etc. The example of an alcohol component may 
include ethyleneglycol, propyleneglycol, glycerin, bisphenol-A, etc. 
Preferably the polyester resins may contain an aromatic dicarboxylic acid 
such as terephthalic acid and an aromatic diaicohol such as bisphenol-A as 
main components. 
The colorant for the toner may include carbon black, Aniline Blue, Chalcoil 
Blue, chrome yellow, ultramarine blue, Du Pont Oil Red, Quinoline Yellow, 
Methylene Blue Chloride, Phthalocyanine Blue, Malachite Green Oxalate, 
lamp black, Rose Bengal, C.I. Pigment Red 48:1, C.I. Pigment Red 12:2, 
C.I. Pigment Red 57:1, C.I. Pigment Yellow 97, C.I. Pigment Yellow 12, 
C.I. Pigment Yellow 17, C.I. Pigment Black 15:1, C.I. Pigment Blue 15:3, 
etc. These colorants may be dispersed directly in the binding resin by 
means of a kneader, or a masterbatch or flushing coloring material may be 
adopted to improve the dispersion of the colorants in the resin and color 
development. 
A releasing agent may be added to the developer used in the present 
invention in order to improve the gloss and offset. Preferably, the 
releasing agent may include paraffin or polyparaffin having carbon atoms 
of more than eight, and may include paraffin wax, paraffin latex, 
microcrystalline wax, etc., or polypropylene, polyethylene, etc. These 
releasing agent may be used alone or in combination therewith. The amount 
thereof is preferably in the range of 0.3 to 10% by weight. 
A charge controlling agent may be added to the toner used in the present 
invention, if it is necessary. The charge controlling agent may include 
convnetional ones, for example, fluorine-containing surfactant; 
metal-containing dye such as salicylic acid metal complex, azo-metal 
compound, etc.; polyacid such as copolymer containing maleic acid as a 
monomer component, etc.; quatenary ammonium salt; azine-dye such as 
Nigrosine, etc.; carbon black; or charge controlling resin, etc. One 
example of the salicylic acid metal complex may be illustrated the 
compounds having the following structural formulae. When these compounds 
are added to the toner particles in addition to the titanium compound 
aforesaid, the charging amount of toner on the sleeve and carriage/layer 
forming state at continuous use may be significantly stabilized and an 
environmental dependency of charging may be significantly reduced. 
##STR2## 
(wherein M is an atom selected from the group consisting of Zn, Fe, Ni, 
and Co. R.sub.1 and R.sub.2 are independently hydrogen atom or alkyl group 
having 1 to 6 carbon atoms.) 
##STR3## 
(wherein M is an atom selected from the group consisting of Cr, Ni, and 
Co. R.sub.1 and R.sub.2 are independently hydrogen atom or alkyl group 
having 1 to 6 carbon atoms. X.sup.+ is a counter ion such as H.sup.+, 
Na.sup.+, K.sup.+, NH.sub.4.sup.+, etc.) 
##STR4## 
(wherein M is an atom selected from the group consisting of Cr, Ni, and 
Co. R.sub.1 and R.sub.2 are independently hydrogen atom or alkyl group 
having 1 to 6 carbon atoms. X.sup.+ is a counter ion such as H.sup.+, 
Na.sup.+, K.sup.+, NH.sub.4.sup.+, etc.) 
##STR5## 
(wherein M is an atom selected from the group consisting of Cr, Ni, and 
Co. R.sub.1 and R.sub.2 are independently hydrogen atom or alkyl group 
having 1 to 6 carbon atoms. X.sup.+ is a counter ion such as H.sup.+, 
Na.sup.+, K.sup.+, NH.sub.4.sup.+, etc.) 
Of these charge controlling agent, the salicylic acid metal complex having 
Zn, B, or Cr atom illustrated by the following structural formulae may be 
preferable in terms of sharpness of the charging distribution and admixing 
property, more preferably the salicylic acid metal complex having Zn atom. 
These charge controlling agent may be used in the range of 0.1 to 10 
weight percent, preferably in the range of 1 to 7 weight percent based on 
the resin. 
When the amount of the charge controlling agent based on the resin is less 
than 0.1% by weight, charge keeping property can not be obtained. The 
offset and image intensity decrease, which cause a fixation failure, when 
more than 10% by weight. 
##STR6## 
A releasing agent may be added to the toner used in the present invention 
in order to improve anti-offset property. A paraffin, polyolefin, etc., 
having carbon atoms of more than eight, for example, paraffin wax, 
paraffin latex, microcrystalline wax, etc, or polupropylene, polyethylene, 
etc. may be preferable as the releasing agent. These releasing agents may 
be used alone or in combination therewith preferably in the range of 0.3 
to 10% by weight. 
The particle diameter of the toner used in the present invention is in the 
range of 3 to 15 .mu.m, preferably in the range of 5 to 10 .mu.m by volume 
average particle diameter. When the volume average particle diameter is 
less than 3 .mu.m, the layer can not be satisfactorily formed due to the 
decreased fluidity, and thus fogging or dirt may be caused. On the other 
hand, when it is more than 15 .mu.m, a high image quality can not be 
obtained due to decreased resolution, and lines tend to easily occur in 
the layer on the development sleeve because of coarse particles. 
The toner used in the present invention may be produced by any conventional 
methods, more preferably, a kneading, pulverization, etc. The process may 
be preferable, which comprises the step of: melting and kneading a binding 
resin and a colorant, and optionally a charging-controlling agent by means 
of a kneading apparatus such as a kneader or extruder, etc., cooling, and 
pulverizing by means of a jet mill or mechanical pulverizer, 
air-classifying, and then adding and mixing additives. 
In the present invention, the titanium compound and optionally silica are 
added to the toner particles, and mixed. Mixing may be carried out by 
means of a V-type blender or Henschel mixer, Redige mixer, etc. In this 
step, a various kinds of additives may be added, if necessary. Examples of 
these additives may include fine particles magnetite and cerium oxide, 
etc. as an abrasive; organic fine particles of 
polystyrene/polymethylmethacrylate, etc.; or inorganic fine particles of 
titanium oxide etc. having relatively large particle diameter as a 
development/transfer auxiliary, fine particles of polyvinylidene fluoride 
etc. as a cleaning auxiliary. 
If necessary, the coarse particles of the toner may be removed by means of 
a vibratory screen classifier or an air screen classifier. 
The amount of charge of the toner used in the present invention is measured 
by a blow-off charge measuring device manufactured by TOSHIBA CHEMICAL Co. 
Ltd. after mixing 30 g of iron powder having 100 .mu.m diameter with 1.2 g 
of the toner by means of a tubular mixer with stirring for 60 seconds. The 
measurement was carried out under ambient temperature of 22.degree. C. and 
humidity of 55%. 
The particle size of the toner used in the present invention was measured 
by means of a Granulometer TA-II having an aperture of 100 .mu.m diameter 
manufactured by COALTER COUNTER Co. Ltd. 
The specific gravity of the titanium compound used in the present in the 
present invention is measured by means of a Le Chatelie's specific gravity 
bottle according to JIS-K-0061 5-2-1. The procedures are as follows; 
i) About 250 ml of water are added to the Le Chatelie's specific gravity 
bottle and adjusted the meniscus to the scale. 
ii) The specific bottle is immersed in a constant temperature water bath 
and the position of the meniscus is accurately read off by the scale of 
the specific gravity bottle when the temperature of the water comes to 
20.0.degree..+-.0.2.degree. C. (The precision is 0.025 ml). 
iii) About 100 g of samples are weighed in order of 1 mg and the weight 
thereof is indicated by W. 
iv) The samples weighed are put in the specific gravity bottle and bubbles 
are removed. 
v) The specific gravity bottle is immersed in the constant temperature 
water bath and the position of the meniscus is accurately read off by the 
scale of the specific gravity bottle while maintaining the temperature of 
the water at 20.0.degree..+-.0.2.degree. C. (The precision is 0.025 ml). 
vi) The specific gravity is calculated by the following procedures; 
EQU D=W/(L.sub.2 -L.sub.1) 
EQU S=D/0.9982 
wherein D is density (20.degree. C.)(g/cm.sup.3); 
S is specific gravity of the sample (20.degree./20.degree. C.); 
W is apparent weight of the sample (g); 
L.sub.1 is reading of the meniscus before the sample is put in the specific 
gravity bottle (20.degree. C.)(ml); 
L.sub.2 is reading of the meniscus after the sample was put in the specific 
gravity bottle (20.degree. C.)(ml); 
0.9982 is density of water at 20.degree. C. (g/cm.sup.3). 
The method for measuring BET specific surface area is as follows; 
The surface area is measured by means of BETA-SOAP auto surface measuring 
apparatus (Model 4200, manufactured by NIKKISO Co. Ltd.) using mixed gas 
of nitrogen and helium. 
The method for forming a multicolor image according to the third aspect of 
the present invention comprises at least a step of developing repeatedly a 
latent image formed on a latent image-holding member by plural developers, 
and a step of transferring collectively on transfer sheet a multicolor 
toner image formed by superimposition on said latent image-holding member 
or intermediate transfer sheet, and more in detail, comprises a step of 
forming the latent image on the latent image-holding member, a step of 
developing repeatedly said latent image formed on said latent 
image-holding member by plural developers, a step of transferring 
collectively on transfer paper a toner image formed by superimposition on 
said latent image-holding member or intermediate transfer sheet, and a 
step of heat-fixing said toner image on said transfer paper. 
The method for forming a multicolor image according to the third aspect of 
the present invention is able to make use of similar image-forming 
processes and similar developers to those used in the image-forming 
processes according to the first and second aspects of the present 
invention. 
EXAMPLES 
Although the present invention is described with reference to Examples, it 
should be understood that the present invention is not limited thereto. In 
the following description, the `part` means `part by weight`, unless 
otherwise noted. 
In the present invention, the titanium oxide formed by wet process, that 
is, sulfuric acid process or hydrochloric acid process may be used. The 
titanium oxide used in Examples was prepared by wet sedimentation process 
comprising dissolving an ilmenite ore in sulfuric acid to separate iron 
therefrom, and hydrolyzing TiOSO.sub.4 to form TiO(OH).sub.2. 
The key techniques in this preparation are hydrolysis and controlling of 
dispersion for the preparation of nuclei, and controlling of agglomeration 
of nuclei particles and rinsing of nuclei particles. In particularly, a 
controlling at high level of a pH-adjustment (neutralization of acid) and 
the concentration of slurry in the dispersion treatment/controlling of 
agglomeration of nuclei particles are required to determine the primary 
particle of titanium compound in succeeding step, including adjustment of 
pH, temperature, etc., at the step of treatment of silicone oil. 
Preparation of External Additive I-A 
25 parts by weight of dimethylsilicone oil (KF 96:made from SHINETSU 
KAGAKUKOHGYOH CO. LTD.) were added to 100 parts of TiO(OH).sub.2 prepared 
by the above-mentioned procedure and mixed while heating, then rinsing, 
filtrating, drying at 120.degree. C., deagglomerating soft agglomeration 
by a pin mill to obtain a titanium compound, External Additive I-A having 
an average primary particle diameter of 3 nm and a specific gravity of 
3.3. 
Preparation of External Additive I-B 
Similar procedures to those for External Additive I-A were repeated except 
that the pH-adjustment for the adjustment of particle diameter and 
dispersion/agglomeration controlling step were changed, to obtain a 
titanium compound, External Additive I-B having an average primary 
particle diameter of 25 nm and a specific gravity of 3.1. 
Preparation of External Additive I-C 
Similar procedures to those for External Additive I-B were repeated except 
that the addition amount of silicone oil were changed to 40 parts by 
weight, to obtain a titanium compound, External Additive I-C having an 
average primary particle diameter of 25 nm and a specific gravity of 3.1. 
Preparation of External Additive I-D 
Similar procedures to those for External Additive I-A were repeated except 
that a fluorine-modified silicone oil (X-70-180A: made from SHINETSU 
KAGAKUKOHGYOH CO.LTD.) was used for the dimethylsilicone oil, to obtain a 
titanium compound, External Additive I-D having an average primary 
particle diameter of 35 nm and a specific gravity of 3.4. 
Preparation of External Additive I-E 
Similar procedures to those for External Additive I-A were repeated except 
that a carboxyl-modified silicone oil (X-22-3701E; made from SHINETSU 
KAGAKUKOHGYOH CO.LTD.) was used for the dimethylsilicone oil, to obtain a 
titanium compound, External Additive I-E having an average primary 
particle diameter of 35 nm and a specific gravity of 3.3. 
Preparation of External Additive I-F 
TiO(OH).sub.2 prepared by the procedures as described above was rinsed, 
filtrated and calcined to obtain a titanium compound having an average 
primary particle diameter of 35 nm. Then, it was pulverized by means of a 
jet mill, and 100 parts by weight of titania compound were treated under 
dry with 25 parts by weight of dimethylsilicone oil in fluidized bed to 
obtain a titanium compound, External Additive I-F having an average 
primary particle diameter of 35 nm and a specific gravity of 4.0. 
Preparation of External Additive I-G 
TiO(OH).sub.2 prepared by the procedures as described above was rinsed, 
filtrated and calcined to obtain a titanium compound having an average 
primary particle diameter of 35 nm. Then, it was pulverized by means of a 
jet mill, and dispersed in methanol, and then 40 parts by weight of 
dimethylsilicone oil were added to 100 parts by weight of titania. After 
the treatment, a wet pulverizing was carried out by means of a sand 
grinder, then the solvent was removed while stirring by a kneader, and 
finally dried to obtain External Additive I-G (specific gravity=3.9). 
Preparation of External Additive I-H 
TiO(OH).sub.2 prepared by the procedures as described above was rinsed, 
filtrated and calcined to obtain a titanium compound having an average 
primary particle diameter of 25 nm. Then, it was dispersed again in water, 
and wet-pulverized by means of a sand grinder, and then, in the water, 40 
parts by weight of isobuthyltrimethoxysilane were mixed, stirred, 
heat-treated, dried, and pulverized by means of a jet mill to obtain 
External Additive I-H having a specific gravity of 3.9. 
Preparation of External Additive I-I 
The similar procedures to those for External Additive I-H were repeated 
except that the amount was changed to 10 parts by weight to obtain 
External Additive I-I having an average primary particle diameter of 25 nm 
and a specific gravity of 3.8. 
Preparation of Toner Grain I-X 
Binding resin (terephthalic acid/bisphenol-A propylene oxide adduct, 
Mw=18,500, Tg=68.degree. C.): 96 parts 
Phthalocyanine pigment(C. I. Pigment Blue 15:3): 4 parts 
The above described materials were mixed by means of Henschel mixer, 
kneaded in a molten state by Bumbury's mixer, and pulverized after being 
cooled, and then classified by means of a screen classifier to obtain a 
Toner Grain I-X having average particle diameter of 8 .mu.m. The charging 
amount of the Toner Grain I-X was -8 .mu.c/g. 
Preparation of Toner Grain I-Y 
Binding resin (terephthalic acid/bisphenol-A propylene oxide adduct, 
Mw=35,000, Tg=66.degree. C.): 89 parts 
Carbon black(BP1300: made from Cabot): 9 parts 
Charging-controlling agent(BONTRON E88: made from ORIENT KAGAKU KOHGYOH 
CO.LTD.): 2 parts 
The above described materials were mixed by means of Henschel mixer, 
kneaded in a molten state by Bumbury's mixer, and pulverized after being 
cooled, and then classified by means of a screen classifier to obtain a 
Toner Grain I-Y having average particle diameter of 7.5 .mu.m. The 
charging amount of the Toner Grain I-Y was -12 .mu.c/g. 
Reparation of Toner Grain T-Z 
Binding resin (styrene-n-butylacrylate copolymer, copolymeriation ratio: 
85/15, MW=13,500, Tg=64.degree. C.): 90 parts 
Yellow pigment (C.I. Pigment Yellow 97): 4 parts 
Polypropylene of low molecular weight (Viscole 660P: made from SANYOH KASEI 
CO.LTD.): 4 parts 
Polyethylene of low molecular weight (molecular weight=6,000): 2 parts 
The above described materials were mixed by means of Henschel mixer, 
kneaded in a molten state by a continuous keading apparatus (TEM 35) 
manufactured by TOSHIBA KIKAI CO.LTD., and pulverized by I-type mill after 
being cooled, and then classified by means of an inertia-type screen 
classifier to obtain Toner Grain I-Z having average particle diameter of 7 
.mu.m. The charging amount of Toner Grain I-Z was -10 .mu.C/g. 
An Image Forming Apparatus 
FIG. 1 shows the image forming apparatus used for evaluation of the image 
quality in the present invention. The latent image-holding member 101 and 
the developer-holding member 103 were arranged with maintaining a definite 
space between them. The latent image-holding member 101 was designed so 
that an electrostatic latent image could be formed by exposure to the 
laser light after being charged by the roller charger 102, and the 
alternating voltage and direct voltage were applied to the 
developer-holding member 103 and developer-supplying roller 104 to develop 
the latent image. The layer-forming blade of silicone rubber 105 was 
contacted directly with the developer-holding member 103 at constant line 
pressure to form a thin layer of the toner. The peripheral speed of the 
latent image-holding member (photosensitive material) 101 was 60 mm/s and 
that of the developing roll 103 was 90 mm/s. The roller transferring 
apparatus 106 was used to transfer of the toner, and the blade-type 
cleaner 107 was used for cleaning. The developer-holding member 103 was 
made from alumite. 
EXAMPLE 1 
1.0 part by weight of External Additive I-A was added to 100 parts by 
weight of Toner Grain I-X and mixed together by means of Henschel mixer, 
and classified by means of air screen classifier having a mesh diameter of 
45 .mu.m to obtain Developer I-1. The charging amount of Developer I-1 was 
-32 .mu.C/g. 
EXAMPLE 2 
The same procedures as those of Example 1 were repeated except that 
External Additive I-A was replaced with External Additive I-B to obtain 
Developer I-2. The charging amount of Developer I-2 was -28 .mu.C/g. 
EXAMPLE 3 
The same procedures as those of Example 1 were repeated except that 
External Additive I-A was replaced with External Additive I-C to obtain 
Developer I-3. The charging amount of Developer I-3 was -29 .mu.C/g. 
EXAMPLE 4 
The same procedures as those of Example 1 were repeated except that 
External Additive I-A was replaced with External Additive I-D to obtain 
Developer I-4. The charging amount of Developer I-4 was -34 .mu.C/g. 
EXAMPLE 5 
The same procedures as those of Example 2 were repeated except that Toner 
Grain I-X was replaced with Toner Grain I-Y to obtain Developer I-5. The 
charging amount of Developer I-5 was -40 .mu.C/g. 
EXAMPLE 6 
The same procedures as those of Example 5 were repeated except that 
External Additive I-B was replaced with External Additive I-E to obtain 
Developer I-6. The charging amount of Developer I-6 was -35 .mu.C/g. 
EXAMPLE 7 
The same procedures as those of Example 3 were repeated except that Toner 
Grain I-X was replaced with Toner Grain I-Z to obtain Developer I-7. The 
charging amount of Developer I-7 was -27 .mu.C/g. 
EXAMPLE 8 
The same procedures as those of Example 7 were repeated except that 
External Additive I-C was replaced with External Additive I-D to obtain 
Developer I-8. The charging amount of Developer I-8 was -31 .mu.C/g. 
EXAMPLE 9 
The same procedures as those of Example 8 were repeated except that the 
amount of External Additive added was replaced with 0.5 parts by weight to 
obtain Developer I-9. The charging amount of Developer I-9 was -27 
.mu.C/g. 
Comparative Example 1 
The same procedures as those of Example 1 were repeated except that 
External Additive I-A was replaced with External Additive I-F to obtain 
Developer I-10. The charging amount of Developer I-10 was -19 .mu.C/g. 
Comparative Example 2 
The same procedures as those of Example 1 were repeated except that 
External Additive I-A was replaced with External Additive I-G to obtain 
Developer I-11. The charging amount of Developer I-11 was -23 .mu.C/g. 
Comparative Example 3 
The same procedures as those of Example 1 were repeated except that 
External Additive I-A was replaced with External Additive I-H to obtain 
Developer I-12. The charging amount of Developer I-12 was -21 .mu.C/g. 
Comparative Example 4 
The same procedures as those of Example 1 were repeated except that 
External Additive I-A was replaced with an amorphous titanium of 30 nm 
particle diameter to obtain Developer I-13. The charging amount of 
Developer I-13 was -5 .mu.C/g. 
Comparative Example 5 
The same procedures as those of Example 5 were repeated except that 
External Additive I-B was replaced with External Additive I-G to obtain 
Developer I-14. The charging amount of Developer I-14 was -21 .mu.C/g. 
Comparative Example 6 
The same procedures as those of Example 5 were repeated except that 
External Additive I-B was replaced with a silica fine particle of 16 nm 
particle diameter treated with dimethylsilicone oil to obtain Developer 
I-15. The charging amount of Developer I-15 was -25 .mu.C/g. 
Comparative Example 7 
The same procedures as those of Example 5 were repeated except that 
External Additive I-B was replaced with a silica fine particle of 12 nm 
particle diameter treated with hexamethylsilazane to obtain Developer 
I-16. The charging amount of Developer I-16 was -23 .mu.C/g. 
Comparative Example 8 
The same procedures as those of Example 7 were repeated except that 
External Additive I-C was replaced with External Additive I-F to obtain 
Developer I-17. The charging amount of Developer I-17 was -16 .mu.C/g. 
Comparative Example 9 
The same procedures as those of Example 7 were repeated except that 
External Additive I-C was replaced with a silica fine particle of 16 nm 
particle diameter treated with fluorine-denatured silicone oil (same kind 
of External Additive I-D) to obtain Developer I-18. The charging amount of 
Developer I-18 was -26 .mu.C/g. 
Comparative Example 10 
The same procedures as those of Example 7 were repeated except that 
External Additive I-C was replaced with 0.5 parts by weight of a silica 
fine particle of 12 nm particle diameter treated with dimethylsilicone oil 
and External Additive I-H of 0.5 parts by weight to obtain Developer I-19. 
The charging amount of Developer I-19 was -18 .mu.C/g. 
Developers I-1 through I-19 obtained by the processes as described above 
were subjected to printing test for 10,000 sheets of paper under both of 
the environment of high temperature and high humidity at 30.degree. C. and 
90% RH, respectively, and low temperature and low humidity at 10.degree. 
C. and 20% RH, respectively, by the image forming apparatus illustrated in 
FIG. 1. The results were shown in Table 1. 
The evaluation of each characteristic in Table 1 was according to the 
following; 
Toner Fluidity (*1) 
Toner fluidity was evaluated by making use of off-line auger dispenser. 
Dispenser desired was .gtoreq.700 mg/sec. 
Initial Charging Amount (*2) 
The toner was carried on the sleeve, and was allowed to stand under each 
environment for 24 hours. Evaluated under each environment by means of 
suction tribo-measuring method. The charging amount after carriage of 
10,000 sheets of paper was measured by the same method as described above. 
Total Evaluation of Charging (*3) 
1)Difference in Charging Under Different Environments 
Difference in charging under different environment=1/2 {initial charging 
amount(at high temperature and high humidity)/(at low temperature and low 
humidity)! +charging amount after carriage of 10,000 sheets of paper(at 
high temperature and high humidity)/(at low temperature and low 
humidity)!}. 
Criteria for evaluation of difference charging under different environment: 
.smallcircle..gtoreq.0.7, .DELTA..gtoreq.0.5, .times.&lt;0.5, 
2) Keeping Property 
Keeping property=1/2 charging amount at high temperature and high humidity 
(charging amount after carriage of 10,000 sheets of paper)/(initial 
charging amount)+charging amount at low temperature and low 
humidity(charging amount after carriage of 10,000 sheets of 
paper)/(initial charging amount)!. 
Criteria for evaluation of keeping property: .smallcircle..gtoreq.0.8, 
.DELTA..gtoreq.0.5, .times.&lt;0.5 
3)Charging Distribution 
Charging distribution was obtained by measuring the charging distribution 
on the sleeve after carriage of 10,000 sheets of paper by means of 
charging distribution measuring apparatus and by dividing the central 
value of the distribution by the breadth of the distribution. Criteria for 
evaluation of charging amount: .smallcircle..gtoreq.0.6, 
.DELTA..gtoreq.0.4, .times.&lt;0.4 
Total Evaluation of Image Quality (*4) 
i) fogging 
Sensory evaluation by observation of background with the aid of 50.times. 
magnifier. 
Criteria for evaluation of fogging: .circle.=nil, .DELTA.=several, 
.times.=fairly, .times..times.=beyond evaluation. 
ii) unevenness in image density/carriage failure Solid evaluation--Density 
was measured at three points (from upper to lower side in A4 sized paper) 
by means of Macbeth densitometer to evaluate. 
iii) density keeping property 
The densities of initial copy and the 10,000th copy were measured 
respectively by means of Macbeth densitometer to evaluate 
iv) failure in image quality 
The failure in image quality because of defects of photosensitive material 
was visually evaluated. 
v) internal adhesion of the apparatus 
The state of deposition because of flying of the toner and sleeve line was 
visually evaluated. 
vi) hollow character 
The state of hollow character in the region of line of 0.1 mm width was 
visually evaluated. . 
Criteria for evaluation of hollow character: .smallcircle.=nil, 
.DELTA.=several, .times.=fairly, .times..times.=beyond evaluation. 
TABLE 1 
__________________________________________________________________________ 
Charging 
amount after 
Initial 
carriage of 
charging 
1000 sheets 
amount 
of paper 
Total evaluation of charging 
(.mu.C/g)*2 
(.mu.C/g) 
(After 10,000)*3 
Total evaluation of image quality(*4) 
At At At At Difference in Image 
high 
low 
high 
low 
charging Unevennes Internal 
failure 
temp. 
temp. 
temp. 
temp. 
under Fogging 
of image ad- between 
Fluidity 
& & & & different Charging 
Charging 
of density, 
Density 
hesion 
lines 
(mg/ high 
low 
high 
low 
environ- 
Keeping 
distri- 
distri- 
back- 
carriage 
keeping 
of 
(Hollow 
sec)*1 hum. 
hum. 
hum. 
hum. 
ments property 
bution 
bution 
ground 
failure 
property 
machine 
character) 
__________________________________________________________________________ 
Ex. 
1 880 (.smallcircle.) 
-14 
-18 
-12 
-16 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
2 940 (.smallcircle.) 
-13 
-16 
-12 
-14 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
3 910 (.smallcircle.) 
-15 
-17 
-11 
-16 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
4 900 (.smallcircle.) 
-17 
-21 
-14 
-19 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
5 860 (.smallcircle.) 
-15 
-18 
-11 
-16 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
6 760 (.smallcircle.) 
-11 
-16 
-9 
-14 
.DELTA. 
.smallcircle. 
.DELTA. 
.smallcircle. 
.DELTA. 
.smallcircle. 
.smallcircle. 
.DELTA. 
.smallcircle. 
7 780 (.smallcircle.) 
-13 
-17 
-11 
-15 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
8 810 (.smallcircle.) 
-18 
-24 
-14 
-19 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
9 710 (.smallcircle.) 
-13 
-17 
-11 
-16 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.DELTA. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
C.E. 
1 600 (x) 
-7 
-10 
-4 
-7 
.DELTA. 
.DELTA. 
x x x .smallcircle. 
.DELTA. 
x .smallcircle. 
2 680 (x) 
-6 
-11 
-5 
-9 
.DELTA. 
.smallcircle. 
x x .DELTA. 
.smallcircle. 
.DELTA. 
.DELTA. 
.smallcircle. 
3 670 (x) 
-8 
-12 
-5 
-8 
.DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
x x .DELTA. 
.smallcircle. 
x 
4 570 (x) 
-2 
+1 
0 -1 
x x xx x xx x .DELTA. 
xx x 
5 710 (.smallcircle.) 
-8 
-13 
-5 
-9 
.DELTA. 
.DELTA. 
x .DELTA. 
.DELTA. 
.smallcircle. 
x x .smallcircle. 
6 890 (.smallcircle.) 
-8 
-19 
-6 
-14 
x .DELTA. 
x x .smallcircle. 
.smallcircle. 
x .DELTA. 
.smallcircle. 
7 930 (.smallcircle.) 
-9 
-18 
-6 
-17 
x .DELTA. 
x x .smallcircle. 
.smallcircle. 
.DELTA. 
.DELTA. 
x 
8 580 (x) 
-6 
-9 
-5 
-10 
.DELTA. 
.DELTA. 
.DELTA. 
.DELTA. 
x x .DELTA. 
.DELTA. 
.smallcircle. 
9 940 (.smallcircle.) 
-9 
-24 
-5 
-20 
xx .DELTA. 
x x .smallcircle. 
.DELTA. 
.smallcircle. 
.DELTA. 
.smallcircle. 
10 780 (.smallcircle.) 
-8 
-15 
-4 
-9 
.DELTA. 
.DELTA. 
x x .smallcircle. 
.smallcircle. 
.smallcircle. 
x .DELTA. 
__________________________________________________________________________ 
C.E. = Comparative Example 
Preparation of External Additive II-A 
50 parts by weight of isobutyltrimethoxysilane were mixed with 100 parts of 
TiO(OH).sub.2 prepared by the procedure as described above, reacted while 
heating, then rinsed, filtrated, dried at 120.degree. C. and 
deagglomerating soft agglomeration by means of pin mill to obtain a 
titanium compound, External additive II-A having average particle diameter 
of 30 nm, specific gravity of 3.1 and resistance of 5.8.times.10.sup.10 
.OMEGA..multidot.cm. 
Preparation of External Additive II-B 
The similar procedures to those for External Additive II-A were carried out 
except that PH-adjustment and dispersion controlling to control the 
particle diameter were changed and 40 parts by weight of 
isobutyltrimethoxysilane were mixed to obtain a titanium compound, 
External Additive II-B having particle diameter of 50 nm, specific gravity 
of 3.1 and resistance of 9.8.times.10.sup.9 .OMEGA..multidot.cm. 
Preparation of External Additive II-C 
The similar procedures to those for External Additive II-B were carried out 
except that PH-adjustment and dispersion controlling to control the 
particle diameter were changed to obtain a titanium compound, External 
Additive II-C having particle diameter of 70 nm, specific gravity of 3.1 
and resistance of 8.5.times.10.sup.9 .OMEGA..multidot.cm. 
Preparation of External Additive II-D 
The similar procedures to those for External Additive II-A were carried out 
except that isobutyltrimethoxysilane was replaced with 
decyltrimethoxysilane to obtain a titanium compound, External Additive 
II-D having particle diameter of 30 nm, specific gravity of 3.4 and 
resistance of 8.0.times.10.sup.10 .OMEGA..multidot.. cm. 
Preparation of External Additive II-E 
The TiO(OH).sub.2 prepared by the procedure as described above was rinsed, 
filtrated, calcined, and obtained a titanium oxide having particle 
diameter of 30 nm. And then, it was pulverized by means of a jet mill to 
obtain External Additive II-E having specific gravity of 3.9 and 
resistance of 6.0.times.10.sup.6 .OMEGA..multidot.cm. 
Preparation of External Additive II-F 
External additive II-E was dispersed in methanol. 40 parts by weight of 
isobutyltrimethoxysilane were mixed to 100 parts by weight of External 
Additive II-E, subjected to a wet-pulverization by means of a sand 
grinder, and stirred to remove a solvent by means of a kneader, and then 
dried to obtain External Additive II-F having specific gravity of 3.9 and 
resistance of 3.0.times.10.sup.9 .OMEGA..multidot.cm. 
Preparation of External Additive II-G 
The TiO(OH).sub.2 prepared by the procedure as described above was rinsed, 
filtrated, calcined, and obtained a titanium oxide having particle 
diameter of 30 nm. And then, it was dispersed in water again, after a 
wet-pulverization by means of a sand grinder. 40 parts by weight of 
isobutyltrimethoxysilane were mixed in the water, and stirred, dried, and 
then pulverized by means of a jet mill to obtain External Additive II-G 
having specific gravity of 3.9 and resistance of 4.2.times.10.sup.9 
.OMEGA..multidot.cm. 
Preparation of Toner Grain II-1 
Polyester resin: 92 parts by weight (terephthalic acid/bisphenol-A 
propyleneoxide adduct, Mw=11,000, Mn=3,300, Tg=67.degree. C., softening 
point=97.degree. C.) Phthalocyanine (C.I. Pigment Blue 15:3) pigment: 5 
parts by weight 
Charging controlling agent: 3 parts by weight 
(Zn Salicylic Acid Complex Compound of Example (1)) 
The materials as described above were mixed together by means of a Henschel 
mixer, kneaded in a molten state by means of an extruder and pulverized by 
means of a jet mill after being cooled, and then classified by means of a 
screen classifier to obtain Cyan-Toner Grain II-1 having an average 
particle diameter of 9.0 .mu.m. 
Preparation of Toner Grain II-2 
The similar procedures to those for Toner particle II-1 were repeated 
except that the colorant was replaced with 5 parts by weight of C.I. 
Pigment Red 57:1 to obtain Magenta Toner Grain II-2 having an average 
particle diameter of 9.1 .mu.m. 
Preparation of Toner Grain II-3 
The similar procedures to those for Toner Grain II-1 were repeated except 
that the colorant was replaced with 5 parts by weight of C.I. Pigment 
Yellow 17 to obtain Yellow Toner Grain II-3 having an average particle 
diameter of 9.2 .mu.m. 
Preparation of Toner Grain II-4 
The similar procedures to those for Toner Grain II-1 were repeated except 
that the colorant was replaced with 4 parts by weight of carbon black to 
obtain Black Toner Grain II-4 having an average particle diameter of 9.0 
.mu.m. 
Preparation of Toner Grain II-5 
Polyester resin: 92 parts by weight (terephthalic acid/glycerin/bisphenol-A 
propyleneoxide adduct, Mw=18,000, Mn=3,800, Tg=65.degree. C., softening 
point=105.degree. C.) Phthalocyanine (C.I. Pigment Blue 15:3) pigment: 5 
parts by weight Charging controlling agent: 3 parts by weight 
(Zn Salicylic Acid Complex Compound of Example (3)) 
The materials as described above were mixed together by means of a Henschel 
mixer, kneaded in a molten state by means of an extruder, and pulverized 
by means of a jet mill after being cooled, and then classified by means of 
a screen classifier to obtain Cyan Toner Grain II-5 having an average 
particle diameter of 9.0 .mu.m. 
Preparation of Toner Grain II-6 
The similar procedures to those for Toner Grain II-5 were repeated except 
that the colorant was replaced with 5 parts by weight of C.I. Pigment Red 
122 to obtain Magenta Toner Grain II-7 having an average particle diameter 
of 9.0 .mu.m. 
Preparation of Toner Grain II-7 
The similar procedures to those for Toner Grain II-5 were repeated except 
that the colorant was replaced with 5 parts by weight of C.I. Pigment 
Yellow 17 to obtain Yellow Toner Grain II-7 having an average particle 
diameter of 9.2 .mu.m. 
Preparation of Toner Grain II-8 
The similar procedures to those for Toner Grain II-5 were repeated except 
that the colorant was replaced with 4 parts by weight of carbon black to 
obtain Black Toner Grain II-8 having an average particle diameter of 9.3 
.mu.m. 
Image Forming Apparatus 
FIG. 2 shows the image forming apparatus used for an evaluation of image 
quality of non-magnetic mono-component developer. The developer-holding 
member 202 having four color developer comprising yellow, magenta, cyan 
and black is arranged with a gap of 150 .mu.m between the latent 
image-holding member 201 and the developer-holding member 202. The latent 
image-holding member 201 was designed so that after the latent 
image-holding member 201 was charged by the roller charger 203, and 
electrostatic latent image was formed by an exposure to laser light, and 
said electrostatic latent image was developed by applying alternating 
voltage and direct voltage to said developer-holding member 203 and 
developer-supplying roller 204, and the charging/exposure/development 
processes of four color toner were repeated in four cycles. The formation 
of the layer of the developer was carried out by contacting the 
layer-forming blade of silicone rubber 205 directly with the 
developer-holding member 202 at a definite line pressure. The transferring 
of the toner was carried out by winding transfer paper 207 around the 
transfer drum 206 and superimposing a toner image on the latent 
image-holding member 201 on the transfer paper 207 with respect to each 
color. The fixing was carried out by a heat-fixing apparatus 208. Herein, 
the peripheral speed of the latent image-holding member 201 was 130 mm/s, 
and the peripheral speed of the developer-holding member 200 mm/s, and the 
cleaning of non-transferred toner on the latent image-holding member 201 
was carried out by making use of blade-type cleaner 208. 
EXAMPLE 10 
1.0 part by weight of External Additive II-A and 0.8 parts by weight of 
silica fine particle, the surface of which being hydrophobic-treated with 
a dimethylsilicone oil, having BET specific surface area of 110 m.sup.2 /g 
were mixed with 100 parts by weight of Toner Grains II-1 through II-4 by 
means of Henschel mixer, and screen-classified by means of air screen 
classifier having a mesh diameter of 45 .mu.m to obtain Developers II-1 
through II-4. The Developers II-1 through II-4 were put into the 
developing apparatuses of cyan, magenta, yellow and black of the 
image-forming apparatus showed in FIG. 2, and print tests of a total of 
10,000 sheets of paper were carried out under two kinds of environments to 
evaluate changes after every 1,000 sheets of paper, that is, environment 
at high temperature of 28.degree. C. and high humidity of 85% RH, and 
environment at low temperature of 10.degree. C. and low humidity of 30% 
RH., to obtain continuously a high image quality without unevenness in 
image density and fogging, etc. The results were shown in Table 2. 
EXAMPLE 11 
The similar procedures to those for Example 10 were carried out except that 
External Additive II-A was replaced with External Additive II-D, to obtain 
Developers II-5 through II-8. An evaluation test for image quality was 
carried out for Developers II-5 through II-8 as described in Example 10, 
to obtain continuously the same high image quality as that of Example 10. 
The results were shown in Table 2. 
EXAMPLE 12 
1.2 parts by weight of External Additive II-B and 0.6 parts by weight of 
silica fine particle, the surface of which being hydrophobic-treated with 
a dimethyldichlorosilane, having BET specific surface area of 120 m.sup.2 
/g were mixed with 100 parts by weight of Toner Grains II-1 thorough II-4 
by means of Henschel mixer, and screen-classified by means of air screen 
classifier having a mesh diameter of 45 .mu.m to obtain Developers II-9 
through II-12. An evaluation test for image quality was carried out for 
Developers II-9 through II-12 as described in Example 10, to obtain 
continuously the same high image quality as that of Example 10. The 
results were shown in Table 2. 
EXAMPLE 13 
1.3 parts by weight of External Additive II-C was mixed with 100 parts by 
weight of Toner Grains II-1 through II-4 by means of Henschel mixer, and 
screen-classified by means of air screen classifier having mesh of 45 
.mu.m to obtain Developers II-13 through II-16. An evaluation test for 
image quality was carried out for Developers II-13 through II-16 as 
described in Example 10, to obtain continuously the same high image 
quality as that of Example 10. The results were shown in Table 2. 
EXAMPLE 14 
1.0 part by weight of External Additive II-A and 0.9 parts by weight of 
silica fine particle, the surface of which being hydrophobic-treated with 
a dimethylsilicone oil, having BET specific surface area of 60 m.sup.2 /g 
were mixed with 100 parts by weight of Toner Grains II-1 through II-4 by 
means of Henschel mixer, and screen-classified by means of air screen 
classifier having a mesh diameter of 45 .mu.m to obtain Developers II-17 
through II-20. An evaluation test for image quality was carried out for 
Developers II-17 through II-20 as described in Example 10, to obtain 
continuously the same high image quality without unevenness and fogging, 
etc., as that of Example 10. The results were shown in Table 2. 
EXAMPLE 15 
1.0 part by weight of External Additive II-B and 0.8 parts by weight of 
silica fine particle, the surface of which being hydrophobic-treated with 
a dimethylsilicone oil, having BET specific surface area of 90 m.sup.2 /g 
were mixed with 100 parts by weight of Toner Grains II-5 through II-8 by 
means of Henschel mixer, and screen-classified by means of air screen 
classifier having a mesh diameter of 45 .mu.m to obtain Developers II-21 
through II-24. An evaluation test for image quality was carried out for 
Developers II-21 through II-24 as described in Example 10, to obtain 
continuously the same high image quality without unevenness and fogging, 
etc., as that of Example 10. The results were shown in Table 2. 
EXAMPLE 16 
The similar procedures to those for Example 15 were carried out except that 
External Additive II-B was replaced with External additive II-C to obtain 
Developers II-25 through II-28. An evaluation test for image quality was 
carried out for Developers II-25 through II-28 as described in Example 10, 
to obtain continuously the same high image quality without unevenness, 
fogging, etc., as that of Example 10. The results were shown in Table 2. 
EXAMPLE 17 
1.0 part by weight of External Additive II-D and 0.7 parts by weight of 
silica fine particle, the surface of which being hydrophobic-treated with 
a hexamethylene disilazane, having BET specific surface area of 70 m.sup.2 
/g were mixed with 100 parts by weight of Toner Grains II-5 through II-8 
by means of Henschel mixer, and screen-classified by means of air screen 
classifier having a mesh diameter of 45 .mu.m to obtain Developers II-29 
through II-32. An evaluation test for image quality was carried out for 
Developers II-29 through II-32 as described in Example 10, to obtain 
continuously the same high image quality without unevenness, fogging, 
etc., as that of Example 10. The results were shown in Table 2. 
EXAMPLE 18 
1.0 part by weight of External Additive II-A was mixed with 100 parts by 
weight of Toner Grains II-5 through II-8 by means of Henschel mixer, and 
screen-classified by means of air screen classifier having a mesh diameter 
of 45 .mu.m to obtain Developers II-33 through II-36. An evaluation test 
for image quality was carried out for Developers II-33 through II-36 as 
described in Example 10, to obtain continuously the same high image 
quality as that of Example 10. The results were shown in Table 2. 
Comparative Example 11 
The similar procedures to those for Example 10 were carried out except that 
External Additive II-A was replaced with External Additive II-E to obtain 
Developers II-37 through II-40. An evaluation test for image quality was 
carried out for Developers II-37 through II-40 as described in Example 10. 
As the result, a numerous fogging was observed in the image from the 
beginning and the internal adhesion of the apparatus occurred with 
violence because of flying of the toner. The results were shown in Table 
2. 
Comparative Example 12 
The similar procedures to those for Example 10 were carried out except that 
External Additive II-A was replaced with External Additive II-F to obtain 
Developers II-41 through II-44. An evaluation test for image quality was 
carried out for Developers II-41 through II-44 as described in Example 10. 
As the result, the image density is decreased after about 1,500th copying 
and the fogging and flying of the toner became worse. The results were 
shown in Table 2. 
Comparative Example 13 
The similar procedures to those for Example 17 were carried out except that 
External Additive II-D was replaced with External Additive II-G to obtain 
Developers II-45 through II-48. An evaluation test for image quality was 
carried out for Developers II-45 through II-48 as described in Example 10. 
As the result, the image density is decreased after about 2,000th copying 
and the fogging and flying of the toner became worse. The results were 
shown in Table 2. 
Comparative Example 14 
The similar procedures to those for Example 18 were carried out except that 
External Additive II-A was replaced with External Additive II-F to 
obtained Developers II-49 through II-52. An evaluation test for image 
quality was carried out for Developers II-49 through II-52 as described in 
Example 10. As the result, a numerous fogging was observed in the image 
from the beginning and the internal adhesion of the apparatus occurred 
with violence because of flying of the toner. The results were shown in 
Table 2. 
Comparative Example 15 
1.0 part by weight of silica fine particle, the surface of which being 
hydrophobic-treated with a dimethylsilicone oil, having BET specific 
surface area of 110 m.sup.2 /g was mixed with 100 parts by weight of Toner 
Grains II-1 through II-4 by means of Henschel mixer, and screen-classified 
by means of air screen classifier having a mesh diameter of 45 .mu.m to 
obtain Developers II-53 through II-56. An evaluation test for image 
quality was carried out for Developers II-53 through II-56 as described in 
Example 10. As the results, a numerous fogging was observed in the image 
from the beginning, and lines occurred on the developing roll after about 
500th copying and the image density dependent on environment varied 
significantly. The results were shown in Table 2. 
Comparative Example 16 
1.0 part by weight of silica fine particle, the surface of which being 
hydrophobic-treated with a dimethyldichlorosilane, having BET specific 
surface area of 120 m.sup.2 /g was mixed with 100 parts by weight of Toner 
Grains II-5 through II-8 by means of Henschel mixer, and screen-classified 
by means of air screen classifier having a mesh diameter of 45 .mu.m to 
obtain Developers II-57 through II-60. An evaluation test for image 
quality was carried out for Developers II-57 through II-60 as described in 
Example 10. As the results, a numerous fogging was observed in the image 
from the beginning, and lines occurred on the developing roll after about 
500th copying and the image density dependent on environment varied 
significantly. The results were shown in Table 2. 
Evaluation Method 
Initial Density 
In the measurement of density by means of a densitometer X-Rite 404A, 
manufactured by X-Rite Co. Ltd,; .times.&lt;1.1, 1.1 .ltoreq..DELTA.&lt;1.4, 1.4 
.ltoreq..smallcircle.. 
Density-keeping Property 
The density after copying of 1000 sheets of paper was evaluated by the same 
method as described above. 
Initial Fogging 
The background of the image was visually observed by 50.times. magnifier 
for sensory evaluation; .smallcircle. - - - nil, .DELTA. - - - several, 
.times. - - - fairly. 
Fogging-keeping Property 
The fogging after copying of 1000 sheets of paper was evaluated by the same 
method as described above. 
Difference in the Density Under Different Environments 
A difference in the densities between under the environment at high 
temperature of 28.degree. C. and 85% RH and under the environment at low 
temperature of 10.degree. C. and 30% RH; 
EQU .smallcircle.&lt;0.2, 0.2 .ltoreq..DELTA.&lt;0.4, 0.4 .ltoreq..times.. 
Line-in the Image, Flying of the Toner, Filming 
The each state was evaluated by visual examination; .smallcircle. - - - 
nil, .DELTA. - - - several, .times. - - - fairly. 
TABLE 2 
__________________________________________________________________________ 
Difference in density 
Initial Density-keeping 
Initial 
Fog-keeping 
under different 
density property 
fogging 
property 
environments 
Line in image 
Flying of toner 
Filming 
__________________________________________________________________________ 
Example 10 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Example 11 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Example 12 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.DELTA. .smallcircle. 
.smallcircle. 
.smallcircle. 
Example 13 
.smallcircle. 
.DELTA. .smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.DELTA. 
.smallcircle. 
Example 14 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Example 15 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Example 16 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Example 17 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.DELTA. .smallcircle. 
.smallcircle. 
.smallcircle. 
Example 18 
.smallcircle. 
.DELTA. .smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.DELTA. 
.smallcircle. 
Comparative 
.smallcircle. 
-- x -- -- -- x -- 
Example 11 
Comparative 
.smallcircle. 
x .smallcircle. 
x .DELTA. x x .DELTA. 
Example 12 
Comparative 
.smallcircle. 
x .smallcircle. 
x .DELTA. x x .DELTA. 
Example 13 
Comparative 
.DELTA. 
-- x -- -- -- x -- 
Example 14 
Comparative 
.DELTA. 
x x x x x x .smallcircle. 
Example 15 
Comparative 
.DELTA. 
x x x x x x .smallcircle. 
Example 16 
__________________________________________________________________________ 
Preparation of External Additive III-A 
40 parts by weight of isobutyltrimethoxysilane were mixed with 100 parts of 
TiO(OH).sub.2 prepared by the procedure as described above, reacted while 
heating, then rinsed, filtrated, dried at 120.degree. C. and 
deagglomerating soft agglomeration by means of pin mill to obtain a 
titanium compound, External Additive III-A, having average particle 
diameter of 25 nm, and specific gravity of 3.1. 
Preparation of External Additive III-B 
The similar procedures to those for External Additive III-A were carried 
out except that PH-adjustment and dispersion controlling to control the 
particle diameter were changed and 40 parts by weight of 
isobutyltrimethoxysilane were mixed, to obtain a titanium compound, 
External Additive III-B, having average particle diameter of 50 nm and 
specific gravity of 3.1. 
Preparation of External Additive III-C 
25 parts by weight of dimethylsilicone oil(KF96, made from SHINETSU 
KAGAKUKOHGYOH Co. LTD.,) were mixed with 100 parts of TiO(OH).sub.2 
prepared by the procedure as described above, reacted while heating. And 
then, the same procedures to those for External Additive III-A were 
carried out to obtain titanium compound, External Additive III-C, having 
average particle diameter of 35 nm and specific gravity of 3.3. 
Preparation of External Additive III-D 
TiO(OH).sub.2 prepared by the procedure as described above was rinsed , 
filtrated, calcined to obtain a titanium oxide having average 
particlediameter of 25 nm. Then, it was pulverized by means of a jet mill 
to obtain External Additive III-D having average particle diameter of 25 
nm and specific gravity of 4.0. 
Preparation of Y Toner Grain 
Binding Resin 95 parts (terephthalic acid/bisphenol-A propylene oxide 
adduct, Mw=3300, Tg=67.degree. C., softening point=97.degree. C.): Yellow 
pigment (C.I. Pigment Yellow 97): 5 parts 
The materials were mixed together by means of Henschel mixer, kneaded in a 
molten state by an extruder, and pulverizedafter by jet mill after being 
cooled, and then classified by means of screen classifier to obtain Yellow 
Grain III-1 having average particle diameter of 9.0 .mu.m. 
Preparation of M Toner Grain 
The similar procedures to those for Toner Grain III-1 were repeated except 
that the colorant was replaced with 5 parts by weight of C.I. Pigment Red 
57:1, to obtain Magenta Toner Grain III-2 having average particle diameter 
of 9.1 .mu.m. 
Preparation of C Toner Grain 
The similar procedures to those for Toner Grain III-1 were repeated except 
that the colorant was replaced with 5 parts by weight of C.I. Pigment Blue 
15:3, to obtain Cyan Toner Grain III-3 having average particle diameter of 
8.9 .mu.m. 
Preparation of K Toner Grain 
The similar procedures to those for Toner Grain III-1 were repeated except 
that the colorant was replaced with 5 parts by weight of carbon black, to 
obtain Black Toner particle III-4 having average particle diameter of 9.0 
.mu.m. 
EXAMPLE 19 
100 parts by weight of each Toner Grain III-1 through III-4, and 1.0 part 
by weight of External Additive III-A, and 0.5 parts by weight of 
hydrophobic silica having BET specific surface area of 60 m.sup.2 /g were 
mixed together by means of Henschel mixer to obtain four color toner. 
EXAMPLE 20 
The similar procedures to those for Example 19 were carried out except that 
External Additive III-A was replaced with External Additive III-B to 
obtain four color toner. 
EXAMPLE 21 
The similar procedures to those for Example 19 were carried out except that 
External Additive III- A was replaced with External Additive III-C to 
obtain four color toner. 
Comparative Example 17 
The similar procedures to those for Example 19 were carried out except that 
External Additive III-A was replaced with External Additive III-D to 
obtain four color toner. 
EXAMPLE 22 
The similar procedures to those for Example 19 were carried out except that 
the BET specific surface area was changed to 15 m.sup.2 /g to obtain four 
color toner. 
EXAMPLE 23 
The similar procedures to those for Example 19 were carried out except that 
the BET specific surface area was changed to 150 m.sup.2 /g to obtain four 
color toner. 
An Image Forming Apparatus 
FIG. 3 shows the image forming apparatus used for evaluation of the image 
quality in the present invention. Four-developing apparatus 210 having 
toners of yellow, magenta, cyan and black were arranged around the latent 
image-holding member 201 (photosensitive material) with a definite space 
between the developer-holding member 202 and the latent image-holding 
member 201. The latent image-holding member 201 was designed so that an 
electrostatic latent image could be formed by exposure to the laser light 
after being charged by Corotron charger 211, and the alternating voltage 
and direct voltage were applied to the developer-holding member 202 and 
developer-supplying roller 204 to develop the latent image. The 
charging/exposure/development of four color toner was carried out in four 
cycle. The formation of the layer of the toner on the developer-holding 
member 202 was carried out by directly contacting the layer-forming blade 
of silicone rubber with the developer-holding member 202 at a constant 
line pressure. The developer-holding member 202 was made from SUS. The 
peripheral speed of the latent image-holding member (photosensitive 
material) 201 was 100 mm/s, and that of the developer-holding member 202 
was 150 mm/s. The toner was transferred by means of the transfer roller 
206, and collectively transferred after superimposing four color toner on 
the photosensitive material, and then fixed through the fixing apparatus 
208. The cleaning was carried out by the blade-type cleaner 209 only at 
the time when the collective-transfer was finished. 
Density-keeping Property, Difference in Density Under Different 
Environments, Fogging-keeping Property, and Filming are evaluated by the 
methods as described previously. Unevenness of density is the difference 
in density in solid images; 
EQU .smallcircle.&lt;0.2, 0.2 .ltoreq..DELTA.&lt;0.4, 0.4 .ltoreq..times.. 
Transfer Efficiency: (weight of the toner image on the transfer 
paper)/(weight of the toner image on the photosensitive material) 
.times.100; 
EQU .times.&lt;89%, 80% .ltoreq..DELTA.&lt;90%, 90% .ltoreq..smallcircle.. 
Table 3 shows that the density-keeping property, the difference in density 
under different environment, and fog-keeping property are poor in 
Comparative Example 17 using titanium compound prepared by calicination. 
TABLE 3 
__________________________________________________________________________ 
Difference In Desnsity 
Density-Keeping 
Under Different 
Unevenness Of 
Fog-Keeping 
Transfer 
Property Environment 
Density 
Property 
Efficiency 
Filming 
__________________________________________________________________________ 
Example 19 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Example 20 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Example 21 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.smallcircle. 
Comparative 
x x .DELTA. 
x .smallcircle. 
.DELTA. 
Example 17 
Example 22 
.smallcircle. 
.smallcircle. 
.DELTA. 
.DELTA. 
.smallcircle. 
.smallcircle. 
Example 23 
.smallcircle. 
.smallcircle. 
.smallcircle. 
.DELTA. 
.DELTA. 
.smallcircle. 
__________________________________________________________________________