JP2001142232A - Method for producing organic pigment, dispersion for electrophotographic photoreceptor, electrophotographic photoreceptor, electrophotographic process, electrophotographic device and process cartridge for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an organic pigment having high stability of the crystalline state and to provide an electrophotographic photoreceptor using the organic pigment, having high sensitivity and not causing the lowering of its electrification ability and the rise of residual potential even after repeated use. SOLUTION: In a method for producing an organic pigment in which the final step of production is a step for bringing out a pigment from a state in which the pigment is kept in contact with at least a solvent, a solvent-containing wet cake is dried by heating at >=75% solid concentration of the pigment and a temperature above room temperature to produce the objective organic pigment. This organic pigment is incorporated into the photosensitive layer of an electrophotographic photoreceptor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an organic pigment, an electrophotographic photosensitive member using the organic pigment produced using the same, and an electrophotographic method and an electrophotographic apparatus using the electrophotographic photosensitive member. And a process cartridge for an electrophotographic apparatus, specifically, a method for producing an organic pigment having excellent dispersibility and crystal stability and good handleability,
Also, the present invention relates to an electrophotographic photosensitive member excellent in stability of a charged potential and a residual potential of the photosensitive member even after repeated use, an electrophotographic method and an electrophotographic apparatus using the same, and a process cartridge for the electrophotographic device.

[0002]

BACKGROUND OF THE INVENTION Organic pigments have been used as fillers in paints for a relatively long time. In particular, the richness of the color is an advantage not found in inorganic pigments. In recent years, as an application example of an organic pigment, various materials have been produced since they came into the spotlight as materials for organic photoelectric conversion devices.

[0003] In forming such a film containing an organic pigment, a wet film forming method, which can be easily enlarged, is predominant. It is no exaggeration to say that the quality of the coating film formed by the wet film formation method is almost completely affected by the quality of the dispersion liquid containing the pigment. Here, the quality of the dispersion is determined by the dispersibility of the pigment. Thus, a good dispersion is one in which the pigment is sufficiently dispersed in the vehicle and the state of dispersion is maintained for a long time.

[0004] In order to prepare such a dispersion, various dispersers and dispersion systems have been proposed so far, and methods for increasing the dispersion efficiency have been devised. In order to reduce the particle size of the pigment in the dispersion, a dispersion medium having a small size is generally used. However, if the pigment is difficult to disperse, the dispersing power is insufficient. The only way to improve this is to increase the media size or use a pigment that is easily dispersed. Since the former has a limit on the particle size to be finally reached, it is efficient to develop the latter method. However, there is almost no approach from the pigment side regarding dispersion.

Further, among the organic pigments, there are polymorphic pigments which have a number of crystal forms as an aggregate even if they are represented by the same structural formula. Among these pigments, there are cases where specific characteristics are exhibited only when a specific crystal form is exhibited,
In such a case, a dispersion method and conditions while maintaining the crystal form are necessary, but there has been no example of studying a method for producing a pigment in consideration of this point.

On the other hand, the development of an information processing system using an electrophotographic system has been remarkable. In particular, optical printers that convert information into digital signals and record information with light have significantly improved print quality and reliability. This digital recording technology is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, a copier equipped with the digital recording technology in a conventional analog copy is expected to increase its demand in the future because various various information processing functions are added.

At present, small, inexpensive and highly reliable semiconductor lasers (LDs) and light emitting diodes (LEDs) are widely used as light sources for optical printers. The emission wavelength of currently used LEDs is 660 nm, and L
The emission wavelength range of D is in the near infrared region. Therefore, development of an electrophotographic photosensitive member having high sensitivity from a visible light region to a near infrared light region is desired.

The photosensitive wavelength range of an electrophotographic photosensitive member is substantially determined by the photosensitive wavelength range of a charge generating substance used in the photosensitive member. Therefore, many charge generation substances such as various azo pigments, polycyclic quinone pigments, trigonal selenium, various phthalocyanine pigments, etc. have been developed. Among them, titanyl phthalocyanine (abbreviated as TiOPc) is 60
In order to show high sensitivity to long wavelength light from 0 to 800 nm,
It is extremely important and useful as a material for a photoreceptor for an electrophotographic printer or a digital copying machine in which a light source is an LED or LD.

On the other hand, the conditions of the electrophotographic photosensitive member repeatedly used in the Carlson process and similar processes include sensitivity, receiving potential, potential holding property, potential stability,
It is required that the electrostatic characteristics represented by the residual potential and the spectral characteristics be excellent. In particular, for high-sensitivity photoreceptors, the chargeability and residual potential increase due to repeated use,
It is empirically known that many photoconductors govern the life characteristics of photoconductors, and titanyl phthalocyanine is no exception. Therefore, the stability of a photoreceptor using titanyl phthalocyanine by repeated use is not yet sufficient, and there has been an eager desire to complete the technology. Further, there has been a demand for a dispersion liquid capable of stably producing a photosensitive member having these characteristics over a long period of time.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an organic pigment having high crystal stability when preparing a dispersion using the organic pigment. Also,
An object of the present invention is to provide a stable electrophotographic photoreceptor which does not cause a decrease in chargeability and an increase in residual potential even when repeatedly used without losing high sensitivity. Another object of the present invention is to provide an electrophotographic photoreceptor having improved abrasion resistance while maintaining the above characteristics. Another object of the present invention is to provide a stable electrophotographic method which does not cause a decrease in chargeability and a rise in residual potential even when repeatedly used without losing high sensitivity. Still another object of the present invention is to provide a stable electrophotographic apparatus and a process cartridge for the electrophotographic apparatus which do not cause a decrease in chargeability and an increase in residual potential even when repeatedly used without losing high sensitivity.

[0011]

Means for Solving the Problems In order to solve the above problems, the present inventors have again studied the dispersibility of organic pigments, changes in crystal type, and the like. Here, the dispersibility of the organic pigment can be roughly classified into pigment crushability and dispersion stability. The latter is based on pigment and vehicle paintability, particle size,
It is determined by factors such as the specific gravity difference between the pigment and the vehicle.
On the other hand, the former is determined by the hardness of the pigment under certain dispersion conditions. In other words, the hardness of the pigment can be said to be the bulk density of the pigment.

[0012] The bulk density of the pigment is not only the density of the pigment itself,
It is greatly affected by the cohesion of the pigment. The minimum unit of the organic pigment particles is a primary particle, and an interaction between the particles occurs due to an intermolecular hydrogen bond or the like to form a secondary particle in which the primary particles are aggregated. The size of the primary particles is substantially determined during the synthesis of the pigment, unless a means for dissolving the pigment such as acid pasting is used. Since one of the secondary particles is an aggregate of the primary particles, the state thereof can be changed by a later process of the pigment synthesis. The bulk density of the pigment is determined by the packing strength of the secondary particles.

As mentioned above, in recent years, organic pigments have been applied as photoelectric conversion materials, and materials showing good characteristics generally have strong cohesive strength and very strong secondary particle packing properties. For this reason, it is very difficult to produce a good dispersion. In addition, even in the case of materials represented by the same chemical structural formula, there are many cases where only a specific crystal type expresses a specific function. Such a specific crystal type may be easily changed by a simple physical or mechanical stress other than the chemical stress. In such a case, it is not preferable to apply much physical and mechanical stress such as dispersion.

In preparing a dispersion using such a pigment having a specific crystal form, two methods are conceivable. One method is to prepare a pigment in which the packing of the secondary particles is reduced as much as possible, and proceed with the dispersion while minimizing the stress at the time of dispersion to produce a dispersion having good dispersion. The other is a method for producing a pigment having a small change in the crystal type with respect to stress during dispersion.

Regarding the former, it is effective to pulverize the pigment to be used as small as possible before dispersing in an organic solvent, or to use a sieve or the like to arrange pigment particles to be used for dispersion in a small substance. It has been proposed as a method and has been used in practice. Certainly, by using these methods, dispersion can be performed in a short time, and a dispersion having a small average particle size can be produced. However,
The stability of the crystal form of the pigment with respect to the solvent, in other words, the storage stability of the crystal form of the pigment in the dispersion was not always satisfactory. On the other hand, by using the latter pigment having high crystal type stability, by performing dispersion using appropriate dispersion conditions, it is possible to produce a dispersion having good dispersibility and high crystal stability. Becomes possible.

Therefore, according to the present invention, first, in the method for producing an organic pigment, wherein the final step of producing the pigment is at least a step of removing the pigment from a state in contact with the solvent, the pigment solid in the wet cake containing the solvent is A method for producing an organic pigment is provided, wherein the organic pigment is heated and dried at a temperature of room temperature or higher (particularly, a temperature of room temperature or higher and lower than the decomposition point of the organic pigment) at a partial concentration of 75% or higher.

Secondly, in the method for producing an organic pigment, wherein the final step of producing the pigment is a step of removing the pigment from at least the state in which the pigment is in contact with the solvent, the pigment solid content in the wet cake containing the solvent is 90% or more. And a method for producing an organic pigment, characterized by drying by heating at a temperature equal to or higher than room temperature.

Thirdly, there is provided the method for producing an organic pigment according to the first or second aspect, wherein the final step is a method for controlling the crystal form of the pigment.

Fourth, the drying step is performed at 1.33 × 10 3
^The method for producing an organic pigment according to any one of the first to third aspects, wherein the method is performed under a reduced pressure of ³ Pa or less.

Fifthly, there is provided the method for producing an organic pigment according to any one of the above-mentioned items 1 to 4, wherein the organic pigment produced in the production method is a phthalocyanine pigment.

Sixthly, there is provided the method for producing an organic pigment according to any one of the first to fourth aspects, wherein the organic pigment produced in the above-mentioned production method is titanyl phthalocyanine.

Seventh, the organic pigment produced by the above-mentioned production method is characterized in that at least CuKα characteristic X-rays (wavelength 1.5
14 °), the maximum diffraction peak at Bragg angle 2θ is 2
(7) The method for producing an organic pigment according to any of (1) to (4) above, wherein the method is titanyl phthalocyanine at a temperature of 7.2 ± 0.2 °.

According to the present invention, eighthly, in a dispersion for an electrophotographic photosensitive member in which an organic pigment is dispersed in at least a solvent, the pigment contained in the dispersion is used at least as a final step of pigment production. An electropigment wherein the pigment is taken out from a state in contact with a solvent, and is an organic pigment which is heated and dried at a temperature of room temperature or higher in a state where the solid concentration of the pigment in a wet cake containing the solvent is 75% or more. A dispersion for a photoreceptor is provided.

Ninth, the organic pigment contained in the dispersion is at least CuKα characteristic X-ray (wavelength 1.514).
The maximum diffraction peak at Bragg angle 2θ with respect to Å) is 27.
The dispersion liquid for an electrophotographic photosensitive member according to the eighth aspect, wherein the dispersion liquid is titanyl phthalocyanine at 2 ± 0.2 °.

According to the present invention, tenth, in an electrophotographic photoreceptor having at least a photosensitive layer provided on a conductive support, the pigment contained in the photosensitive layer is converted into at least a solvent as a final step of pigment production. An organic pigment obtained by removing the pigment from a state in which the pigment is in contact with the organic pigment and drying by heating at a temperature of room temperature or higher in a state where the solid content of the pigment in the wet cake containing the solvent is 75% or higher. A body is provided.

An eleventh aspect provides the electrophotographic photosensitive member according to the tenth aspect, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.

Twelfth, the electrophotographic photosensitive member according to the eleventh feature is provided, wherein the charge transport layer contains a polycarbonate containing at least a triarylamine structure in a main chain and / or a side chain. Is done.

According to the present invention, thirteenth, in an electrophotographic method in which the electrophotographic photosensitive member is repeatedly subjected to at least charging, image exposure, development, transfer, cleaning, and charge removal, the electrophotographic photosensitive member includes at least a pigment. As a final step of the preparation, an organic pigment which is heated and dried at a temperature of room temperature or higher in a state where the pigment is taken out from at least a state where the pigment is in contact with the solvent and the solid concentration of the pigment in the wet cake containing the solvent is 75% or higher is contained. Wherein the photosensitive layer is provided on a conductive support.

According to the present invention, in a fourteenth aspect, there is provided an electrophotographic apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transferring unit, a cleaning unit, a discharging unit, and an electrophotographic photosensitive member. The pigment is taken out of the electrophotographic photoreceptor at least in a state where the electrophotographic photoreceptor is in contact with a solvent at least as a final step of preparing the pigment, and the solid content concentration of the pigment in the wet cake containing the solvent is at least 75% at room temperature or higher. An electrophotographic apparatus is provided, wherein a photosensitive layer containing a heat-dried organic pigment is provided on a conductive support.

Further, according to the present invention, fifteenth, there is provided a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member has at least a solvent as a final step of pigment production. The photosensitive layer containing the organic pigment, which has been heated and dried at a temperature of room temperature or higher in a state where the pigment solids concentration in the wet cake containing the solvent is 75% or more, is taken out of the state where the pigment is brought into contact with the photosensitive layer. A process cartridge for an electrophotographic apparatus is provided, which is provided on a support.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. Organic pigments are generally synthesized by a wet method, and are often handled in a state where the pigment is suspended in a solvent, such as for washing, purification, and crystal conversion. From this state, only the target pigment is taken out, but various methods such as filtration and centrifugation are used. In this step, by setting the pigment to a solid content concentration of 75% or more, a very firmly compacted pigment (having a large bulk density) is produced. Such pigments require more energy for coarse pulverization or dispersion than pigments having a low bulk density. However, the pigment produced in this way has a high crystal stability against an organic solvent and a high crystal stability against mechanical stress such as dispersion, and is easy to use as compared with a pigment having a low bulk density. Another advantage is the good handling in the pigment removal step. Such effects are even more remarkable when the solid content is 90% or more (closer to 100%).

On the other hand, when the solid content concentration of the pigment is less than 75%, the pigment contains a sufficient amount of solvent, and the bulk density is not so large in this state. By immediately heating and drying the pigment in this state at a temperature equal to or higher than room temperature, a pigment having a low bulk density is produced. Such pigments have extremely high dispersibility and are excellent in coarse pulverizability and dispersibility, but have low crystal stability in a solvent as compared with the pigment having a large bulk density. ) The width is extremely narrow, and the manufacturing conditions become severe.

Further, in the above-mentioned pigment removing step, after reaching a predetermined pigment solid content concentration, by heating and drying at a temperature of room temperature or higher, the effect of the present invention becomes remarkable.
This is because, when a certain solid content concentration is exceeded, the tightness of the produced pigment (the magnitude of the bulk density) tends to be saturated, and it is not preferable to keep the organic solvent and the pigment in contact for a long time. This is because it is advantageous to keep it as dry as possible. Further, when the organic solvent used in the final step and the organic solvent used in the dispersion step are different, the residual solvent in the pigment production final step may have an adverse effect. Therefore, by performing the above-mentioned heating and drying step under reduced pressure, specifically, at 1.33 × 10 ³ Pa or less, the effect is further exhibited. The present invention has been made based on the discovery of such a method for producing a pigment.

As the organic pigment prepared in the present invention, any of known organic pigments can be used. Examples thereof include phthalocyanine pigments, monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, and quinacridone. Pigments, quinone-based condensed polycyclic compounds, squaric acid-based dyes, naphthalocyanine-based pigments, azurenium salt-based dyes, and the like are used.

The phthalocyanine pigment having a large number of crystal forms is very effective, and among them, titanyl phthalocyanine is a pigment whose properties are greatly changed depending on the crystal form. In particular, characteristic X-rays of CuKα (wavelength 1.51
4Å), the maximum diffraction peak at Bragg angle 2θ is 2
Titanyl phthalocyanine at 7.2 ± 0.2% has an extremely high photocarrier generation ability, but its crystal form is unstable and easily converted to another crystal form. However, by using the present invention, a dispersion can be produced while maintaining the crystal form stably.

Used to heat and dry pigments above room temperature
Any known dryer can be used.
However, when the drying is performed in the atmosphere, a blast-type dryer is preferable.
Further, the drying speed is increased, and the effects of the present invention are more remarkably exhibited.
Drying under reduced pressure is also a very effective means for achieving this.
In particular, it may decompose at high temperature or change crystal form.
This is an effective means for materials. In the present invention,
1.33 × 10 ^ThreeThe reduced pressure of Pa or less means that:
33 × 10^ThreeIt refers to a state where the degree of vacuum is higher than Pa
is there.

Next, the dispersion for an electrophotographic photosensitive member of the present invention will be described. The dispersion of the electrophotographic photoreceptor has very strict specifications, unlike the dispersion used in ordinary paints. For example, in the case where a pigment having a specific crystal form has a desired function for the first time, a dispersion must be prepared while maintaining the crystal form. Further, in recent electrophotographic processes, the resolution of an image is very important, and accordingly, the particle diameter of the pigment contained in the photoreceptor must be small. In order to prepare such a dispersion, it is necessary to prepare a pigment having good dispersibility from the beginning. As a result of studying in consideration of this point, by using the pigment prepared as described above and dispersing under appropriate dispersion conditions,
It has been found that a dispersion having a small crystal form and a small particle size can be produced.

A general method is used for preparing a dispersion, and the pigment is dispersed in an appropriate solvent together with a binder resin, if necessary, using a ball mill, an attritor, a sand mill, a bead mill, ultrasonic waves, or the like. It is obtained by At this time, the binder resin may be selected according to the electrostatic characteristics of the photoreceptor, and the solvent may be selected according to the wettability to the pigment, the dispersibility of the pigment, and the like.

Next, the electrophotographic photosensitive member of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an electrophotographic photosensitive member used in the present invention.
A single-layer photosensitive layer 33 mainly composed of a charge generation material and a charge transport material is provided thereon. FIGS. 2 and 3 are cross-sectional views showing another configuration example of the electrophotographic photoreceptor used in the present invention. The charge generation layer 35 mainly composed of a charge generation material and the electric charge mainly composed of a charge transport material are shown. The transport layer 37 has a stacked configuration.

The conductive support 31 has a volume resistance of 10
Those exhibiting a conductivity of ¹⁰ Ωcm or less, for example, aluminum, nickel, chromium, nichrome, copper, gold, silver, metals such as platinum, tin oxide, metal oxides such as indium oxide, by evaporation or sputtering, Film or cylindrical plastic or paper coated or plates made of aluminum, aluminum alloy, nickel, stainless steel, etc., and extruded, drawn, etc., made into a tube, then cut, super finished, polished, etc. And the like can be used. Further, an endless nickel belt and an endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support 31.

In addition to the above, a support obtained by dispersing a conductive powder on a suitable binder resin on the above support and applying the same can also be used as the conductive support 31 of the present invention.

Examples of the conductive powder include carbon black, acetylene black, metal powders such as aluminum, nickel, iron, nichrome, copper, zinc and silver, and metal oxide powders such as conductive tin oxide and ITO. And so on.

The binder resins used simultaneously include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate. Copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal,
Polyvinyl toluene, poly-N-vinyl carbazole,
A thermoplastic resin such as an acrylic resin, a silicone resin, an epoxy resin, a melamine resin, a urethane resin, a phenol resin, and an alkyd resin, a thermosetting resin, or a photocurable resin can be used.

Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in an appropriate solvent, for example, tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene, or the like, and applying the dispersion.

Further, heat shrinkage of a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark), or the like containing the conductive powder on a suitable cylindrical substrate. Also those that have a conductive layer provided by a tube,
It can be used favorably as the conductive support 31 of the present invention.

Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a stacked layer, but for convenience of explanation, the case where the photosensitive layer is composed of the charge generation layer 35 and the charge transport layer 37 will be described first.

In the charge generation layer 35, as a final step of pigment preparation, the pigment is taken out from at least the state in contact with the solvent, and the solid content concentration of the pigment in the wet cake containing the solvent is 75% by weight or more and the temperature is higher than room temperature. This is a layer containing an organic pigment obtained by heating and drying at a temperature as a main component of the charge generation material.

The charge-generating layer 35 is formed by ball milling the pigment in a suitable solvent together with a binder resin if necessary.
It is formed by dispersing using an attritor, a sand mill, an ultrasonic wave or the like, applying this to a conductive support, and drying.

If necessary, the binder resin used for the charge generation layer 35 includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, Poly-N-vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl And pyrrolidone.
The amount of the binder resin is 0 to 100 parts by weight of the charge generating substance.
500 parts by weight, preferably 10 to 300 parts by weight, is suitable.

Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. No.

As a method for applying the coating solution, a dip coating method, a spray coat, a beat coat, a nozzle coat, a spinner coat, a ring coat, or the like can be used.
The thickness of the charge generation layer 35 is appropriately about 0.01 to 5 μm, and preferably 0.1 to 2 μm.

The charge transporting layer 37 can be formed by dissolving or dispersing a charge transporting substance and a binder resin in a suitable solvent, applying this on the charge generating layer, and drying. Also,
If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

The charge transporting substance includes a hole transporting substance and an electron accepting substance. Examples of electron acceptors include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,6,8-
Examples thereof include electron accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

Examples of the hole transport material include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives,
α-phenylstilbene derivative, benzidine derivative, diarylmethane derivative, triarylmethane derivative, 9
And other known materials such as styryl anthracene derivative, pyrazoline derivative, divinylbenzene derivative, hydrazone derivative, indene derivative, butadiene derivative, pyrene derivative, bisstilbene derivative, enamine derivative and the like.

These charge transporting substances are used alone or in combination of two or more.

Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and polyacetic acid. Vinyl, polyvinylidene chloride, polyalate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin , A phenol resin, an alkyd resin, and other thermoplastic resins or thermosetting resins.

The solvents used here are tetrahydrofuran, dioxane, toluene, dichloromethane,
Monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

The amount of the charge transporting substance is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, per 100 parts by weight of the binder resin.
Parts by weight are appropriate. The thickness of the charge transport layer is 5 to 100 μm.
m is preferable.

For the charge transporting layer, a polymer charge transporting material having both a function as a charge transporting material and a function as a binder resin is preferably used. The charge transport layer composed of these polymeric charge transport materials has excellent abrasion resistance. As the polymer charge transport material, known materials can be used, but polycarbonates containing a triarylamine structure in the main chain and / or side chain are preferably used. Among them, the polymer charge transport materials represented by the formulas (1) to (10) are preferably used, and these are exemplified below and specific examples are shown.

[0060]

Embedded imageWhere R₁, R_Two, R_ThreeAre each independently substituted or
Unsubstituted alkyl group or halogen atom, R_FourIs a hydrogen atom
Or a substituted or unsubstituted alkyl group, R_Five, R ₆Is replaced
Or an unsubstituted aryl group, o, p and q are each independently
And an integer of 0 to 4, k and j represent compositions, and 0.1 ≦ k
≦ 1, 0 ≦ j ≦ 0.9, n represents the number of repeating units, and
It is an integer of 5000. X is an aliphatic divalent group, a cyclic fat
Group or a divalent group represented by the following general formula:
You.

Embedded image In the formula, R ₁₀₁ and R ₁₀₂ each independently represent a substituted or unsubstituted alkyl group, aryl group or halogen atom.
l and m are integers from 0 to 4, Y is a single bond, and has 1 to 1 carbon atoms.
2 linear, branched or cyclic alkylene group, -O
-, - S -, - SO -, - SO 2 -, - CO -, - CO
—O—Z—O—CO— (wherein, Z represents an aliphatic divalent group) or

Embedded image (In the formula, a represents an integer of 1 to 20, b represents an integer of 1 to 2000, and R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or aryl group.) Where R ₁₀₁ and R ₁₀₂ ,
R ₁₀₃ and R ₁₀₄ may be the same or different.

[0061]

Embedded image In the formula, R ₇ and R ₈ represent a substituted or unsubstituted aryl group, A
r ₁ , Ar ₂ and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (1).

[0062]

Embedded image In the formula, R ₉ and R ₁₀ are a substituted or unsubstituted aryl group,
Ar ₄ , Ar ₅ and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (1).

[0063]

Embedded image In the formula, R ₁₁ and R ₁₂ are a substituted or unsubstituted aryl group,
Ar ₇ , Ar ₈ and Ar ₉ are the same or different arylene groups, p
Represents an integer of 1 to 5. X, k, j and n are (1)
Same as for expressions.

[0064]

Embedded imageWhere R₁₃, R₁₄Is a substituted or unsubstituted aryl group,
Ar_Ten, Ar₁₁, Ar ₁₂Are the same or different arylene groups,
X₁, X_TwoIs a substituted or unsubstituted ethylene group, or
Alternatively, it represents an unsubstituted vinylene group. X, k, j and
n is the same as in the case of equation (1).

[0065]

Embedded image In the formula, R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ are a substituted or unsubstituted aryl group, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ and Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ and Y ₃ are A single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, and a vinylene group may be the same or different. X, k, j and n are
This is the same as in the case of equation (1).

[0066]

Embedded image In the formula, R ₁₉ and R ₂₀ represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (1).

[0067]

Embedded image In the formula, R ₂₁ is a substituted or unsubstituted aryl group, A
r ₂₀ , Ar ₂₁ , Ar ₂₂ and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as in the case of equation (1).

[0068]

Embedded image In the formula, R ₂₂ , R ₂₃ , R ₂₄ , and R ₂₅ are a substituted or unsubstituted aryl group, Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ , Ar ₂₈
Represents the same or different arylene groups. X, k, j and n are the same as in the case of equation (1).

[0069]

Embedded imageWhere R₂₆, R₂₇Is a substituted or unsubstituted aryl group,
Ar₂₉, Ar₃₀, Ar ₃₁Represents the same or different arylene groups
Represent. X, k, j and n are the same as in the case of equation (1).
is there.

In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 37. As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount of the plasticizer is 0 to 30% based on the binder resin.
The degree is appropriate. Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain.
The amount used is suitably from 0 to 1% based on the binder resin.

Next, the case where the photosensitive layer has a single-layer structure 33 will be described. A photoconductor in which the pigment prepared by the above-described specific method is dispersed in a binder resin can be used. The single-layer photosensitive layer is formed by dip coating, spray coating, or beading a coating liquid obtained by dispersing a charge generating substance, a charge transport substance, and a binder resin with a disperser or the like using a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane. It can be formed by coating with a coat or the like. The thickness of the single-layer photosensitive layer is 5 to 10
About 0 μm is appropriate. Further, the photosensitive layer may be of a function-separated type to which the above-described charge transporting substance is added, and can be used favorably. If necessary, a plasticizer, a leveling agent, an antioxidant and the like can be added.

As the binder resin, in addition to using the binder resin previously described for the charge transport layer 37 as it is, the charge generation layer 3
The binder resins described in 5 may be mixed and used. Of course, the above-mentioned polymer charge transport materials can also be used favorably. The amount of the charge generating substance is preferably 5 to 40 parts by weight, and the amount of the charge transporting substance is 0 to 1 part by weight based on 100 parts by weight of the binder resin.
90 parts by weight is preferred, and more preferably 50 to 150 parts by weight.
Parts by weight.

The electrophotographic photosensitive member of the present invention may have an undercoat layer between the conductive support 31 and the photosensitive layer. The undercoat layer generally contains a resin as a main component. However, considering that the photosensitive layer is coated thereon with a solvent, these resins are resins having high solvent resistance to general organic solvents. desirable. Examples of such a resin include water-soluble resins such as polyvinyl alcohol, casein and sodium polyacrylate, alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy resin. Curable resins that form a three-dimensional network structure, such as resins, may be used.

In order to prevent moire and reduce residual potential, a fine powder pigment of a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide, etc. is added to the undercoat layer. Is also good.

These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, the undercoat layer of the present invention includes Al
₂ O ₃ provided by anodic oxidation, organic material such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , Ti
Those provided with an inorganic substance such as O ₂ , ITO, CeO ₂ by a vacuum thin film forming method can also be used favorably. In addition, known materials can be used. The thickness of the undercoat layer is 0 to 5 μm
Is appropriate.

In the electrophotographic photosensitive member of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. The material used for the protective layer is ABS resin, AC
S resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallyl sulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyether sulfone, polyethylene, polyethylene terephthalate,
Polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone,
Examples include resins such as polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, and epoxy resin. Other protective layers include fluororesins such as polytetrafluoroethylene, silicone resins, and inorganic materials such as titanium oxide, tin oxide, and potassium titanate dispersed in these resins for the purpose of improving abrasion resistance. Can be added.

As a method for forming the protective layer, an ordinary coating method is employed. The thickness of the protective layer is suitably about 0.1 to 10 μm. In addition to the above, known materials such as aC and a-SiC formed by a vacuum thin film forming method can be used as the protective layer.

In the present invention, an intermediate layer can be provided between the photosensitive layer and the protective layer. The intermediate layer generally uses a binder resin as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a normal coating method is employed as described above. In addition,
The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

Next, the electrophotographic method and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings. FIG. 4 is a schematic diagram for explaining the electrophotographic process and the electrophotographic apparatus of the present invention, and the following modified examples also belong to the category of the present invention.

In FIG. 4, as a final step of preparing a pigment as a charge-generating material, a pigment is taken out of at least a state in contact with a solvent on a conductive support. 75% concentration
A photosensitive layer containing an organic pigment as a main component obtained by heating and drying at a temperature of room temperature or higher in the above state is provided.

The photosensitive member 1 has a drum shape, but may have a sheet shape or an endless belt shape. Known means such as a corotron, a scorotron, a solid state charger (solid state charger), and a charging roller are used for the charging charger 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13. Can be

As the transfer means, generally, the above-mentioned charger can be used. However, as shown in FIG. 4, a combination of a transfer charger and a separation charger is effective.

The light sources such as the image exposure unit 5 and the neutralizing lamp 2 include a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, and a light emitting diode (LE).
D), semiconductor lasers (LD), electroluminescence (EL), and other general light-emitting materials can be used.
To irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used. Such a light source or the like irradiates the photoreceptor with light by providing a transfer step, a charge removal step, a cleaning step, or a pre-exposure step using light irradiation in addition to the step shown in FIG.

The toner developed on the photosensitive member 1 by the developing unit 6 is transferred to the transfer paper 9, but not all of the toner is transferred, and toner remaining on the photosensitive member 1 is generated. Such toner is removed from the photoconductor by the cleaning brush 14 and the cleaning blade 15. Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.

When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. This is called negative (positive) polarity toner (electrostatic fine particles)
, A positive image can be obtained, and if developed with a toner of positive (negative) polarity, a negative image can be obtained. A known method is applied to the developing means, and a known method is also used for the charge removing means.

FIG. 5 shows another example of the electrophotographic process according to the present invention. The photoreceptor 21 is a state where the pigment is taken out from at least a state in which it is in contact with a solvent as a charge generation material as a charge generating material on a conductive support, and the solid concentration of the pigment in the wet cake containing the solvent is 75% or more. And has a photosensitive layer containing an organic pigment as a main component, which is heated and dried at a temperature equal to or higher than room temperature, is driven by drive rollers 22a and 22b, is charged by a charger 23, is exposed to light by a light source 24, and is developed (not shown). ), Transfer using the charger 25,
Exposure before cleaning by the light source 26, cleaning by the brush 27, and static elimination by the light source 28 are repeatedly performed. In FIG. 5, the photoconductor 21 (of course, the support is translucent in this case) is irradiated with light for pre-cleaning exposure from the support.

The above illustrated electrophotographic process is an example of the embodiment of the present invention, and other embodiments are of course possible. For example, in FIG. 6, the pre-cleaning exposure is performed from the support side, but this may be performed from the photosensitive layer side, or the image exposure and the erasing light irradiation may be performed from the support side.

On the other hand, the light irradiation step includes image exposure, pre-cleaning exposure, and charge removal exposure. However, in addition to the above, a pre-transfer exposure, a pre-exposure of image exposure, and other known light irradiation steps are provided. Light irradiation can also be performed on the body.

The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, or may be incorporated in the apparatus in the form of a process cartridge. The process cartridge includes a photoreceptor, and further includes a charging unit, an exposing unit, a developing unit, a transferring unit, a cleaning unit, and a discharging unit.
Devices (parts). Although there are many shapes and the like of the process cartridge, a general example is shown in FIG. The photoreceptor 16 is provided on a conductive support,
The pigment is taken out from at least a state in contact with a solvent as a final step of preparing a pigment as a charge generating material, and is heated and dried at a temperature of room temperature or higher in a state where a pigment solid content concentration in a wet cake containing a solvent is 75% or more. It has a photosensitive layer containing the obtained organic pigment as a main component.

[0090]

The present invention will be described below with reference to examples.
The present invention is not limited by these embodiments. All parts are parts by weight.

First, a specific synthesis example of a crystalline titanyl phthalocyanine pigment having a maximum diffraction peak at a Bragg angle of 2θ of 27.2 ± 0.2 ° will be described.

Example 1 292 parts of 1,3-diiminoisoindoline and 1800 parts of sulfolane were mixed, and 204 parts of titanium tetrabutoxide were added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C, and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C and 180 ° C. After the reaction, the precipitate was filtered after standing to cool, washed with chloroform until the powder turned blue, washed with methanol several times, further washed with hot water at 80 ° C. several times, and dried. Crude titanyl phthalocyanine was obtained.
60 parts of the obtained crude titanyl phthalocyanine pigment washed with hot water were dissolved in 1,000 parts of 96% sulfuric acid at 3 to 5 ° C. under stirring, dissolved and filtered. The obtained sulfuric acid solution is mixed with ice water 350
The mixture was added dropwise with stirring to 00 parts, and the precipitated crystals were filtered.
Subsequently, washing with water was repeated until the washing liquid became neutral, thereby obtaining a water paste of titanyl phthalocyanine pigment. To 500 parts of this water paste was added 1500 parts of 1,2-dichloroethane, and the mixture was stirred at room temperature for 2 hours. Then, 2500 parts of methanol was further added, followed by stirring and filtration. This was washed with methanol to obtain 98 parts of a pigment wet cake (solid content concentration of the wet cake: 76% by weight). Of these, 50 parts were dried at 70 ° C. in the atmosphere (1.0 × 10 ⁵ Pa) to obtain 38 parts of a titanyl phthalocyanine pigment.

(Example 2) 50 parts of a pigment wet cake prepared in the same manner as in Example 1 (solid content concentration of the wet cake: 76%) was reduced to 7 under reduced pressure (1.33 × 10 ³ Pa).
After drying at 0 ° C., 24 parts of a titanyl phthalocyanine pigment were obtained.

Example 3 A pigment wet cake (solid content: 90%) prepared in the same manner as in Example 1 was dried at 70 ° C. under reduced pressure (6.65 × 10 ² Pa), and similarly titanyl phthalocyanine was obtained. A pigment was obtained.

Comparative Example 1 30 parts of the crude titanyl phthalocyanine obtained in Example 1 was treated with sulfuric acid in the same manner as in Example 1 to obtain a water paste. 250 parts of this water paste
After adding 750 parts of 2-dichloroethane and stirring at room temperature for 2 hours, 1250 parts of methanol was further added, followed by stirring and filtration. This was washed with methanol to obtain 98 parts of a pigment wet cake (solid content of the wet cake: 60% by weight). Of these, 50 parts were reduced pressure (1.33 × 10 ³ P
By drying at 70 ° C. in a), 30 parts of a titanyl phthalocyanine pigment were obtained.

The pigments obtained in Examples 1 to 3 and Comparative Example 1 were roughly pulverized using a commercially available mixer. The coarsely pulverized pigment was classified using a 300-mesh sieve to obtain fine titanyl phthalocyanine pigment powder. X-ray diffraction spectra of the fine titanyl phthalocyanine pigments obtained in Examples 1 to 3 and Comparative Example 1 were measured under the following conditions. X-ray tube Cu, voltage 40 kV, current 20 mA, scanning speed 1 ° / min, scanning range 3 ° to 40 °, time constant 2 seconds.

Since the X-ray diffraction spectra of the titanyl phthalocyanine pigments obtained in Examples 1 to 3 and Comparative Example 1 are all the same, the X-ray diffraction spectra of the pigment obtained in Example 3 are shown as representative examples. FIG.
The obtained titanyl phthalocyanine pigment has a Bragg angle of 2θ.
It can be seen that the maximum diffraction peak has an intended crystal form at 27.2 ± 0.2 °.

These pigments were immersed in 2-butanone and subjected to a one-week storage test. The method is as follows. One part of each pigment is placed in 30 parts of 2-butanone, shaken well, and then stored in a dark place for one week. After a lapse of one month, each pigment was filtered and vacuum dried at 70 ° C. to obtain a dried pigment powder. The X-ray diffraction spectrum of each was measured under the same conditions as described above. As a result, the pigments obtained in Examples 1 to 3 showed the same spectrum as that of FIG.
8 shows the X-ray diffraction spectrum shown in FIG. 8 below, and it can be seen that the crystal form has clearly changed.

Example 4 A dispersion having the following composition was prepared by bead milling under the following conditions (this was used as dispersion 1
And). Titanyl phthalocyanine powder produced in Example 1 10 parts Polyvinyl butyral 10 parts Methyl ethyl ketone 80 parts Using a PSZ ball having a diameter of 1 mm in a commercially available bead mill disperser, all methyl ethyl ketone and pigment in which polyvinyl butyral was dissolved were charged, and the rotor rotation speed was 1000.
The dispersion was performed at rpm for 20 minutes.

Example 5 A dispersion having the following composition was prepared in Example 4.
It was produced by bead milling under the same conditions as above (this is referred to as dispersion liquid 2). Titanyl phthalocyanine powder prepared in Example 2 10 parts Polyvinyl butyral 10 parts Methyl ethyl ketone 80 parts

Example 6 A dispersion having the following composition was prepared in Example 4.
It was prepared by bead milling under the same conditions as described above (this is referred to as dispersion liquid 3). Titanyl phthalocyanine powder prepared in Example 3 10 parts Polyvinyl butyral 10 parts Methyl ethyl ketone 80 parts

Comparative Example 2 A dispersion having the following composition was prepared by bead milling under the following conditions (this is referred to as dispersion 4). Titanyl phthalocyanine powder prepared in Comparative Example 1 10 parts Polyvinyl butyral 10 parts Methyl ethyl ketone 80 parts Using a PSZ ball having a diameter of 1 mm in a commercially available bead mill disperser, all methyl ethyl ketone and pigment in which polyvinyl butyral was dissolved were charged, and the rotor rotation speed was 1000.
rpm. For 5 minutes.

Comparative Example 3 A dispersion of the following composition was prepared in Example 4.
It was prepared by bead milling under the same conditions as described above (this is referred to as dispersion liquid 5). Titanyl phthalocyanine powder prepared in Comparative Example 1 10 parts Polyvinyl butyral 10 parts Methyl ethyl ketone 80 parts

The pigment particle sizes in the dispersions prepared in Examples 4 to 6 and Comparative Examples 2 to 3 were determined by using a Horiba, CAPA.
It was measured by 700 (centrifugal automatic particle size distribution analyzer). Further, the prepared dispersion was dried and powdered, and the X-ray diffraction spectrum was measured in the same manner as described above. The X-ray diffraction spectrum was similar to that of the titanyl phthalocyanine pigment obtained in Example 3. . Subsequently, these pigments were subjected to a storage test under the same conditions as in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 1. It can be seen that the dispersions prepared in Examples 4 to 6 have a small particle size and a stable crystal form.

[0105]

[Table 1]

(Examples 7 to 9 and Comparative Example 4) An undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following compositions having the following compositions were applied on an electroformed nickel belt. Coating and drying were sequentially performed to prepare a laminated photoreceptor. [Undercoat layer coating liquid] Titanium dioxide powder 15 parts Alcohol-soluble nylon 6 parts Ethanol 150 parts [Charge generating layer coating liquid] The dispersions 1, 2, 3, and 5 described above were used. [Charge transport layer coating solution] Polycarbonate 10 parts Charge transport material of the following structural formula 7 parts

Embedded image 80 parts of methylene chloride

The electrophotographic photoreceptor thus formed is shown in FIG.
In the electrophotographic process shown in (1), the image exposure light source was set to a 780 nm semiconductor laser (image writing by a polygon mirror) so that the surface potential of the photoconductor immediately before development could be measured. An electrometer probe was inserted. Printing was continuously performed on 7000 sheets, and the surface potentials of the image-exposed area and the image non-exposed area at that time were measured at the initial stage and after 7000 sheets. Table 2 shows the results. Table 2 shows that the electrophotographic photosensitive members of Examples 7 to 9 maintain a stable surface potential even after repeated use.
In particular, it can be seen that the photosensitive member of Example 9 has a stable surface potential even after repeated use.

[0108]

[Table 2]

(Examples 10 to 12 and Comparative Example 5) Anodizing treatment was performed on the surface of an aluminum cylinder, and then sealing treatment was performed. On this, the following charge generation layer coating solution and charge transport layer coating solution were sequentially applied and dried to form a charge generation layer having a thickness of 0.3 μm and a charge transport layer having a thickness of 24 μm, respectively. A photoreceptor was prepared. [Coating solution for charge generation layer] The above-mentioned dispersions 1 to 4 were used, respectively. [Coating solution for charge transport layer] 8 parts of charge transport material having the following structural formula

Embedded image Polycarbonate 10 parts Methylene chloride 80 parts

The electrophotographic photoreceptor thus formed is shown in FIG.
After mounting in the electrophotographic process cartridge shown in
It was mounted on an image forming apparatus. However, the image exposure light source is 780n
m semiconductor laser (image writing by polygon mirror). 5000 sheets were continuously printed, and the initial and 5000th sheet images were evaluated. Table 3 shows the results.
Table 3 shows that dispersions 5 to 7 were used (Examples 10 to 1).
2) shows that a good image can be obtained both at the initial stage and after repeated use.

[0111]

[Table 3]

(Example 13) A photoconductor was prepared in the same manner as in Example 10 except that the coating solution for the charge transport layer in Example 10 was changed to the following composition. [Coating solution for charge transport layer] 10 parts of polymer charge transport material having the following structural formula

Embedded image 100 parts of methylene chloride

(Example 14) A photoconductor was prepared in the same manner as in Example 10, except that the coating composition for the charge transport layer in Example 10 was changed to the following composition. [Coating solution for charge transport layer] 10 parts of polymer charge transport material having the following structural formula

Embedded image 100 parts of methylene chloride

Each of the electrophotographic photosensitive members of Examples 10 and 13 to 14 was mounted in the electrophotographic process shown in FIG. 4 (however, an image exposure light source was an LD having a light emission at 780 nm), and two continuous electrophotographic photosensitive members were used. After printing 10,000 sheets, the images at that time were evaluated at the initial stage and after 20,000 sheets. Further, a change (decrease amount) in the film thickness of the charge transport layer was measured. Table 4 shows the results. Table 4 shows that the electrophotographic photosensitive members of Examples 13 and 14 exhibited particularly excellent wear resistance.

[0115]

[Table 4]

[0116]

According to the present invention, there is provided a method for producing a dispersible organic pigment (having high crystal stability) without changing the crystal form in producing a dispersion. By using this, a dispersion having a small particle size can be provided while maintaining a specific crystal form. This dispersion is very useful as a dispersion for an electrophotographic photoreceptor, and can provide a photoreceptor having specific photoreceptor characteristics and having few coating film defects. This provides a photosensitive member having high abrasion resistance while maintaining specific characteristics (high sensitivity and stable surface potential even after repeated use). Further, there are provided a stable electrophotographic apparatus and a process cartridge for the electrophotographic apparatus which do not cause a decrease in chargeability and an increase in residual potential even when repeatedly used without losing high sensitivity.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electrophotographic photosensitive member used in the present invention.

FIG. 2 is a schematic sectional view of another electrophotographic photosensitive member used in the present invention.

FIG. 3 is a schematic sectional view of still another electrophotographic photosensitive member used in the present invention.

FIG. 4 is a schematic diagram for explaining an electrophotographic process and an electrophotographic apparatus of the present invention.

FIG. 5 is a schematic diagram for explaining another electrophotographic process and an electrophotographic apparatus of the present invention.

FIG. 6 is a schematic diagram for explaining a typical process cartridge of the present invention.

FIG. 7 is an X-ray diffraction spectrum of the titanyl phthalocyanine pigment obtained in Example 3.

FIG. 8 is an X-ray diffraction spectrum of the titanyl phthalocyanine pigment obtained in Comparative Example 1 after a storage test for one week.

FIG. 9 is an X-ray diffraction spectrum of the titanyl phthalocyanine pigment obtained in Comparative Example 3 after a storage test for one week.

[Explanation of symbols]

 31 conductive support 33 single-layer photosensitive layer 35 charge generation layer 37 charge transport layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 5/06 371 G03G 5/06 371 5/07 103 5/07 103

Claims (15)

[Claims] 1. The method for producing an organic pigment, wherein the final step of producing the pigment is a step of taking out the pigment from at least a state in which the pigment is in contact with a solvent, wherein the solid concentration of the pigment in the wet cake containing the solvent is 75% or more and the room temperature is reduced. A method for producing an organic pigment, comprising heating and drying at the above temperature. 2. The method for producing an organic pigment, wherein the final step of producing the pigment is a step of removing the pigment from at least a state in which the pigment is in contact with the solvent, wherein the solid content of the pigment in the wet cake containing the solvent is 90% or more and the room temperature is reduced. A method for producing an organic pigment, comprising heating and drying at the above temperature. 3. The method according to claim 1, wherein the final step is a method for controlling the crystal form of the pigment.
Or a method for producing an organic pigment according to item 2. 4. The method according to claim 1, wherein the drying step is performed at 1.33 × 10 ³ Pa.
The process is performed under the following reduced pressure.
The method for producing an organic pigment according to any one of the above. 5. The method for producing an organic pigment according to claim 1, wherein the organic pigment produced in the production method is a phthalocyanine-based pigment. 6. The method for producing an organic pigment according to claim 1, wherein the organic pigment produced in the production method is titanyl phthalocyanine. 7. The method according to claim 1, wherein the organic pigment produced by the production method is at least CuKα characteristic X-ray (wavelength 1.514).
The maximum diffraction peak at Bragg angle 2θ with respect to Å) is 27.
The method for producing an organic pigment according to any one of claims 1 to 4, wherein the titanyl phthalocyanine is at 2 ± 0.2%. 8. In a dispersion for an electrophotographic photoreceptor in which an organic pigment is dispersed in at least a solvent, the pigment contained in the dispersion is removed from at least a state in which the pigment is in contact with the solvent as a final step of pigment production. A dispersion for an electrophotographic photoreceptor, wherein the dispersion is an organic pigment which is heated and dried at a temperature of room temperature or higher in a state where the pigment solid content in a wet cake containing a solvent is 75% or more. 9. The organic pigment contained in the dispersion has a maximum diffraction peak at a Bragg angle of 2θ of at least 27.2 ± 0.2 with respect to CuKα characteristic X-ray (wavelength 1.514 °).
9. The dispersion for an electrophotographic photoreceptor according to claim 8, which is titanyl phthalocyanine in 2). 10. An electrophotographic photoreceptor having at least a photosensitive layer provided on a conductive support, wherein the pigment contained in the photosensitive layer is taken out of at least a state in which it is in contact with a solvent as a final step of pigment production. An electrophotographic photoreceptor, which is an organic pigment which has been heated and dried at a temperature of room temperature or higher in a state where the pigment solid content concentration in a wet cake containing a solvent is 75% or more. 11. The electrophotographic photosensitive member according to claim 10, wherein said photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer. 12. The electrophotographic photoreceptor according to claim 11, wherein the charge transporting layer contains a polycarbonate containing at least a triarylamine structure in a main chain and / or a side chain. 13. An electrophotographic photosensitive member comprising:
In an electrophotographic method in which image exposure, development, transfer, cleaning, and static elimination are repeated, the pigment is taken out of the electrophotographic photoreceptor at least in a state where the electrophotographic photosensitive member is in contact with a solvent at least as a final step of pigment production, and the wet cake containing the solvent is removed. Wherein a photosensitive layer containing an organic pigment heated and dried at a temperature of room temperature or higher at a pigment solid content concentration of 75% by weight or more is provided on a conductive support. Method. 14. At least charging means, image exposure means,
An electrophotographic apparatus comprising a developing unit, a transfer unit, a cleaning unit, a charge removing unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is used at least as a final step of preparing a pigment in a state where the pigment is in contact with at least a solvent. A photosensitive layer containing an organic pigment which is removed and heated and dried at a temperature of room temperature or higher in a state where the solid content of the pigment in a wet cake containing a solvent is 75% or more is provided on a conductive support. An electrophotographic apparatus, characterized in that: 15. A process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photoreceptor, wherein a pigment is taken out of the electrophotographic photoreceptor at least in a state where the electrophotographic photoreceptor is in contact with a solvent at least as a final step of pigment preparation,
And the solid content of the pigment in the wet cake containing the solvent is 7
A process cartridge for an electrophotographic apparatus, wherein a photosensitive layer containing an organic pigment which is heated and dried at a temperature of 5% or more at a temperature of room temperature or more is provided on a conductive support.