JP2008195951A - Method for preparing organic pigment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare an organic pigment having high crystal stability, and to provide an electrophotographic photoreceptor by using the organic pigment, having high sensitivity and neither lowering electrostatic-charging properties nor heightening residual potential even after repeated use. <P>SOLUTION: The method for preparing the organic pigment essentially involves a process of taking out the pigment which is in the state of contacting with a solvent as the final process, and is characterized in that a wet cake containing the solvent, wherein the pigment solid concentration is at least 75%, is dried by heating at room temperature or higher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an organic pigment, an electrophotographic photoreceptor using an organic pigment produced using the same, an electrophotographic method using the electrophotographic photoreceptor, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus More specifically, a method for producing an organic pigment having excellent dispersibility and crystal stability and good handleability, an electrophotographic photosensitive member excellent in stability of charging potential and residual potential even after repeated use, and the same. The present invention relates to an electrophotographic method, an electrophotographic apparatus, and a process cartridge for an electrophotographic apparatus.

  Organic pigments have been used as fillers for 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 organic pigments, various materials have been produced since they have been spotlighted as materials for organic photoelectric conversion devices.

  In forming such a film containing an organic pigment, most of the wet film forming methods that can easily increase the area are occupied. It is no exaggeration to say that the quality of a coating film formed by a wet film formation method is almost dependent on the quality of a dispersion containing a pigment. Here, the dispersibility of the pigment is a decisive factor for the quality of the dispersion. Therefore, a good dispersion is one in which the pigment is sufficiently dispersed in the vehicle and the dispersion state continues for a long time.

  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, generally, a dispersion medium having a small size is used. However, if the pigment is difficult to disperse, the dispersion power is insufficient. The only way to improve this is to increase the media size or use pigments that are easily dispersed. Since the former has a limit on the final particle size, it is efficient to develop the latter method. However, there are few approaches from the pigment side regarding dispersion.

  In addition, among organic pigments, there are polymorphic pigments having many crystal forms as aggregates even though 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 that maintain the crystal form are necessary. However, there is no example in which a method for producing a pigment in view of this point has been studied.

  On the other hand, the development of an information processing system using an electrophotographic system is remarkable. In particular, an optical printer that converts information into a digital signal and records information by light is markedly improved in 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, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, it is expected that its demand will increase further in the future.

  As a light source for an optical printer, a small-sized, inexpensive and highly reliable semiconductor laser (LD) or light emitting diode (LED) is currently used. The light emission wavelength of the LED that is often used at present is 660 nm, and the light emission wavelength region of the LD is in the near infrared light region. Therefore, development of an electrophotographic photoreceptor having high sensitivity from the visible light region to the near infrared light region is desired.

  The photosensitive wavelength region of the electrophotographic photosensitive member is almost determined by the photosensitive wavelength region of the charge generating material used in the photosensitive member. Therefore, many charge generating materials such as various azo pigments, polycyclic quinone pigments, trigonal selenium and various phthalocyanine pigments have been developed. Among them, titanyl phthalocyanine (abbreviated as TiOPc) exhibits high sensitivity to light having a long wavelength of 600 to 800 nm, and therefore, a photoconductor material for an electrophotographic printer or digital copying machine whose light source is LED or LD. As extremely important and useful.

  On the other hand, the electrophotographic photosensitive member used repeatedly in the Carlson process and similar processes has excellent electrostatic characteristics such as sensitivity, receptive potential, potential retention, potential stability, residual potential, and spectral characteristics. Is required. In particular, for high-sensitivity photoconductors, it has been empirically known that a decrease in chargeability and an increase in residual potential due to repeated use dominate the lifetime characteristics of photoconductors, and titanyl phthalocyanine is also an exception. is not. Therefore, stability due to repeated use of a photoreceptor using titanyl phthalocyanine has not been sufficient yet, and the completion of the technique has been eagerly desired. Further, there has been a demand for a dispersion that can stably produce a photoconductor having these characteristics for a long period of time.

  An object of the present invention is to provide a method for producing an organic pigment having high crystal stability when producing a dispersion using the organic pigment. Another object of the present invention is to provide a stable electrophotographic photosensitive member that does not cause a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity. Another object of the present invention is to provide an electrophotographic photoreceptor having improved wear 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 an increase in residual potential even after repeated use without losing high sensitivity. Another object of the present invention is to provide a stable electrophotographic apparatus and a process cartridge for an electrophotographic apparatus that do not cause a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity.

  In order to solve the above-mentioned problems, the present inventors have examined the dispersibility of the organic pigment, the change in crystal form, and the like again. Here, the dispersibility of the organic pigment can be broadly classified into the grindability and dispersion stability of the pigment. The latter is determined by factors such as the paintability of the pigment and the vehicle, the particle size, and 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 a certain dispersion condition. In other words, the hardness of the pigment can be said to be the bulk density of the pigment.

  The bulk density of a pigment is greatly influenced by the density of the pigment itself and the cohesive strength of the pigment. The minimum unit of the organic pigment particles is a primary particle, and interaction between particles is generated by intermolecular hydrogen bonding or the like to form secondary particles in which the primary particles are aggregated. The size of the primary particles is almost determined in the process of pigment synthesis unless a means for dissolving the pigment such as acid pasting is used. Since one secondary particle is an aggregate of primary particles, its state can be changed by a post-process of 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. In general, materials exhibiting good characteristics have a high cohesive force and a very strong packing property for secondary particles. For this reason, it is very difficult to produce a good dispersion. Even in the case of materials represented by the same chemical structural formula, there are many cases where only a specific crystal form exhibits a specific function. Such a specific crystal type may easily change due to simple physical / mechanical stress in addition to chemical stress. In such a case, it is not preferable to apply a lot of physical and mechanical stress such as dispersion.

  In preparing a dispersion using such a pigment having a specific crystal type, two methods are conceivable. One is a method in which a pigment having a secondary particle packing as weak as possible is prepared, and the dispersion is promoted in a state in which the stress during dispersion is minimized, thereby producing a dispersion having good dispersion. The other is a method of producing a pigment with little change in crystal form with respect to stress during dispersion.

  As for the former, it is proposed to pulverize the pigment used before dispersion in an organic solvent as small as possible, and to arrange the pigment particles used for dispersion in a small object by using a sieve etc. Has been used in practice. Certainly, by using these methods, dispersion can be completed in a short time, and a dispersion having a small average particle size can be produced. However, the stability of the crystal form with respect to the solvent of the pigment, 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 with high crystal type stability, by carrying out dispersion using appropriate dispersion conditions, a dispersion having good dispersibility and high crystal stability can be produced. Is possible.

  Therefore, according to the present invention, first, in the organic pigment preparation method in which the final step of preparing the pigment is a step of taking out the pigment from a state in contact with the solvent, the pigment solid content concentration in the wet cake containing the solvent is There is provided a method for producing an organic pigment, which is dried by heating at a temperature of 75% or more at a temperature of room temperature or more (more precisely, a temperature of room temperature or more and a decomposition point or less).

  Second, in the method for producing an organic pigment, in which the final step of producing the pigment is a step of taking out the pigment from a state in contact with the solvent, the pigment solid content concentration in the wet cake containing the solvent is 90% or more at room temperature or higher. There is provided a method for producing an organic pigment, characterized in that it is heated and dried at a temperature of

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

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

  Fifth, the organic pigment produced in the production method is a phthalocyanine pigment, and the method for producing an organic pigment according to any one of the first to fourth aspects is provided.

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

  Seventh, the organic pigment produced in the production method is titanyl phthalocyanine having a Bragg angle 2θ maximum diffraction peak of 27.2 ± 0.2 ° with respect to at least CuKα characteristic X-ray (wavelength 1.541 波長). There is provided a method for producing an organic pigment according to any one of the first to fourth aspects.

  Further, according to the present invention, eighthly, in the 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 in contact with at least the solvent as a final step of preparing the pigment. For an electrophotographic photosensitive member, characterized in that the pigment is removed from the dried state, and is an organic pigment that is dried by heating at a temperature of room temperature or higher at a pigment solid content concentration of 75% or higher in a wet cake containing a solvent. A dispersion is provided.

  Ninth, the organic pigment contained in the dispersion is titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of 27.2 ± 0.2 ° with respect to at least CuKα characteristic X-rays (wavelength 1.541Å). The dispersion for an electrophotographic photosensitive member according to the eighth aspect is provided.

  According to the present invention, tenthly, in the electrophotographic photosensitive member in which at least a photosensitive layer is provided on a conductive support, the pigment contained in the photosensitive layer is in contact with at least a solvent as the final step of preparing the pigment. Provided is an electrophotographic photosensitive member characterized in that it is an organic pigment obtained by removing the pigment from the state and being dried by heating at a temperature of room temperature or higher at a pigment solid content concentration of 75% or higher in a wet cake containing a solvent. Is done.

  Eleventh, the electrophotographic photosensitive member according to the tenth aspect is provided, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer.

  Twelfth, there is provided the electrophotographic photoreceptor according to the eleventh aspect, wherein the charge transport layer contains a polycarbonate having at least a triarylamine structure in the main chain and / or side chain.

  According to the invention, thirteenthly, in the electrophotographic method in which at least charging, image exposure, development, transfer, cleaning, and charge removal are repeated on the electrophotographic photosensitive member, the electrophotographic photosensitive member is at least the final pigment preparation. Photosensitivity containing an organic pigment that is removed from at least a solvent in contact with the solvent and heated and dried at a temperature of room temperature or higher at a pigment solid content concentration of 75% or higher in the wet cake containing the solvent. An electrophotographic method is provided, wherein the layer is provided on a conductive support.

  According to the present invention, in the 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 charge eliminating unit, and an electrophotographic photosensitive member. At least the pigment is taken out from the state in which the photographic photoconductor is in contact with the solvent at least as the final step of producing the pigment, and is dried by heating at a temperature of room temperature or higher at a pigment solid content concentration of 75% or higher in the wet cake containing the solvent. An electrophotographic apparatus is provided in which a photosensitive layer containing an organic pigment is provided on a conductive support.

  Furthermore, according to the present invention, in the fifteenth aspect, there is provided a process cartridge for an electrophotographic apparatus comprising at least an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is in contact with at least a solvent as at least a final step of producing a pigment. A photosensitive layer containing an organic pigment that has been dried by heating at a temperature of room temperature or higher with a pigment solid content concentration of 75% or higher in a wet cake containing a solvent removed from the state on a conductive support. The process cartridge for an electrophotographic apparatus is provided.

  According to the present invention, there is provided a method for producing a dispersible organic pigment without changing the crystal form (high crystal stability) in producing a dispersion. By using this, a dispersion having a fine particle size is 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 few coating film defects. This provides a photoconductor having high wear resistance while maintaining specific characteristics (high sensitivity and stable surface potential even after repeated use). Furthermore, there are provided a stable electrophotographic apparatus and a process cartridge for an electrophotographic apparatus that do not cause a decrease in chargeability and an increase in residual potential even after repeated use without losing high sensitivity.

  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 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 pigment that is very tight (a bulk density) is produced. Such pigments require greater energy for coarse pulverization or dispersion than pigments with a low bulk density. However, the pigment prepared in this manner is rich in crystal stability against organic solvents and crystal stability against mechanical stress such as dispersion, and is easier to use than pigments with a low bulk density. In addition, good handling in the above-mentioned pigment removal step is also an advantage. Such an effect is even more remarkable when the solid content concentration is 90% or more (a state closer to 100%).

  On the other hand, when the solid content concentration of the pigment is less than 75%, the solvent is sufficiently contained, and the bulk density is not so large in this state. The pigment in this state is immediately heated and dried at a temperature equal to or higher than room temperature to produce a pigment having a small bulk density. Such pigments have extremely high dispersibility and excellent coarse pulverization and dispersibility, but their crystal stability against solvents is lower than that of pigments with a large bulk density, and in actual use, selection (setting of dispersion conditions) ) The width is extremely narrow and the manufacturing conditions are severe.

In the above-mentioned pigment removal step, after reaching a predetermined pigment solid content concentration, the effect of the present invention becomes remarkable by heating and drying at a temperature of room temperature or higher. This is because when the solid content concentration exceeds a certain level, the degree of tightening of the pigment (the bulk density) tends to saturate, and it is not preferable to keep the organic solvent in contact with the pigment for a long time. This is because it is advantageous to keep it as dry as possible. Furthermore, if the organic solvent used in the final step is different from the organic solvent used in the dispersion step, the residual solvent in the final step of pigment production may have an adverse effect. Therefore, the effect is further demonstrated by performing the above-mentioned heat drying process under reduced pressure, specifically 1.33 × 10 ³ Pa or less. The present invention has been made on the basis of finding such a method for producing a pigment.

  Any of the known organic pigments can be used as the organic pigment produced in the present invention. For example, phthalocyanine pigments, monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perinone pigments, quinacridone pigments, Examples thereof include quinone-based condensed polycyclic compounds, squaric acid-based dyes, naphthalocyanine-based pigments, and azulenium salt-based dyes.

  It is very effective for phthalocyanine pigments having a large number of crystal types. In particular, titanyl phthalocyanine is a pigment whose properties vary greatly depending on the crystal type. In particular, titanyl phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ of 27.2 ± 0.2 ° with respect to the characteristic X-ray (wavelength 1.541 波長) of CuKα has an extremely high photocarrier generation ability, but has a poor crystal form. It is stable and easily converted into another crystal form. However, by using the present invention, a dispersion can be produced while maintaining a stable crystal form.

Any known dryer can be used to heat and dry the pigment at room temperature or higher. However, when it is performed in the air, a blower-type dryer is preferable. Furthermore, drying under reduced pressure is a very effective means in order to increase the drying speed and to exhibit the effects of the present invention more remarkably. In particular, it is an effective means for a material that decomposes at a high temperature or changes its crystal form. In the present invention, “under reduced pressure of 1.33 × 10 ³ Pa or less” refers to a state in which the degree of vacuum is higher than 1.33 × 10 ³ Pa.

  Next, the dispersion for an electrophotographic photoreceptor of the present invention will be described. The dispersion for electrophotographic photoreceptors has very strict specifications, unlike the dispersion used for ordinary paints. For example, in the case where a pigment having a specific crystal form has a desired function for the first time, it is necessary to prepare a dispersion while maintaining the crystal form. In recent electrophotographic processes, the resolution of an image is very important, and the particle size of the pigment contained in the photoreceptor must be small accordingly. 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 with this point in mind, it was found that by using the pigment prepared as described above and dispersing under appropriate dispersion conditions, a dispersion with a small crystal size and a small particle size can be produced. I found it.

  A general method is used for preparing the dispersion, and the pigment is obtained by dispersing the pigment in a suitable solvent together with a binder resin as necessary using a ball mill, an attritor, a sand mill, a bead mill, an ultrasonic wave, or the like. Is. At this time, the binder resin may be selected depending on the electrostatic characteristics of the photoreceptor, and the solvent may be selected depending on the wettability to the pigment, the dispersibility of the pigment, and the like.

  Next, the electrophotographic photosensitive member according to 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, and a single-layer photosensitive layer 33 mainly composed of a charge generating material and a charge transporting material is provided on a conductive support 31. . 2 and 3 are cross-sectional views showing another configuration example of the electrophotographic photosensitive member used in the present invention, in which a charge generation layer 35 mainly composed of a charge generation material and a charge mainly composed of a charge transport material. The transport layer 37 has a laminated structure.

Examples of the conductive support 31 include those having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, indium oxide, etc. The metal oxides of the above are coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc. and the like by extrusion, drawing, etc. After pipe formation, surface treatment pipes such as cutting, superfinishing, and polishing can be used. Further, an endless nickel belt or an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can also be used as the conductive support 31.

  In addition, the conductive support 31 of the present invention can be used in which conductive powder is dispersed in a suitable binder resin and coated on the support.

  Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done.

  The binder resin used at the same time is 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, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic resins such as melamine resin, urethane resin, phenol resin, and alkyd resin, thermosetting resin, and photocurable resin.

  Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, it is electrically conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also 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 laminate, but for convenience of explanation, the case where it is composed of the charge generation layer 35 and the charge transport layer 37 will be described first.

  The charge generation layer 35 is heated at a temperature of room temperature or higher in a state where the pigment is taken out from at least the state in contact with the solvent as a final step of pigment preparation and the pigment solid content concentration in the wet cake containing the solvent is 75% by weight or higher. This is a layer mainly composed of an organic pigment obtained by drying.

  In the charge generation layer 35, the pigment is dispersed in a suitable solvent together with a binder resin, if necessary, using a ball mill, an attritor, a sand mill, an ultrasonic wave, etc., and this is coated on a conductive support and dried. Is formed.

  As the binder resin used for the charge generation layer 35 as necessary, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicon resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N -Vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. can give. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material.

  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.

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

  The charge transport layer 37 can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

  The charge transport material includes a hole transport material and an electron accepting material. Examples of the electron acceptor include chloroanil, bromoanil, 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-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

  Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned.

  These charge transport materials may be used alone or in combination of two or more.

  Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarate, 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, phenol resin And thermoplastic resins such as alkyd resins or thermosetting resins.

  As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used.

  The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 μm.

  In addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the charge transport layer. The charge transport layer composed of these polymer charge transport materials is excellent in wear resistance. A known material can be used as the polymer charge transporting material, but a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the formulas (1) to (10) are favorably used, and these are exemplified below and specific examples are shown.

式中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立して置換もしくは無置換のアルキル基又はハロゲン原子、Ｒ_４は水素原子又は置換もしくは無置換のアルキル基、Ｒ_５、Ｒ_６は置換もしくは無置換のアリール基、ｏ、ｐ、ｑはそれぞれ独立して０〜４の整数、ｋ、ｊは組成を表し、０．１≦ｋ≦１、０≦ｊ≦０．９、ｎは繰り返し単位数を表し５〜５０００の整数である。Ｘは脂肪族の２価基、環状脂肪族の２価基、または下記一般式で表される２価基を表す。

In the formula, R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₅ and R ₆ are substituted or unsubstituted. Substituted aryl group, o, p and q are each independently an integer of 0 to 4, k and j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n is the number of repeating units Represents an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula.

式中、Ｒ_１０１、Ｒ_１０２は各々独立して置換もしくは無置換のアルキル基、アリール基またはハロゲン原子を表す。ｌ、ｍは０〜４の整数、Ｙは単結合、炭素原子数１〜１２の直鎖状、分岐状もしくは環状のアルキレン基、−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ_２−、−ＣＯ−、−ＣＯ−Ｏ−Ｚ−Ｏ−ＣＯ−（式中Ｚは脂肪族の２価基を表す。）または、

In the formula, R ₁₀₁ and R ₁₀₂ each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or

（式中、ａは１〜２０の整数、ｂは１〜２０００の整数、Ｒ_１０３、Ｒ_１０４は置換または無置換のアルキル基又はアリール基を表す。）を表す。ここで、Ｒ_１０１とＲ_１０２、Ｒ_１０３とＲ_１０４は、それぞれ同一でも異なってもよい。

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

式中、Ｒ_７、Ｒ_８は置換もしくは無置換のアリール基、Ａｒ_１、Ａｒ_２、Ａｒ_３は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

In the formula, R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar 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).

式中、Ｒ_９、Ｒ_１０は置換もしくは無置換のアリール基、Ａｒ_４、Ａｒ_５、Ａｒ_６は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

In the formula, R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and 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).

式中、Ｒ_１１、Ｒ_１２は置換もしくは無置換のアリール基、Ａｒ_７、Ａｒ_８、Ａｒ_９は同一又は異なるアリレン基、ｐは１〜５の整数を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

_{Wherein, R 11,} R ₁₂ is a substituted or unsubstituted aryl _{group, Ar 7, Ar 8, Ar} 9 are identical or different arylene group, p is an integer of 1-5. X, k, j, and n are the same as in the case of equation (1).

式中、Ｒ_１３、Ｒ_１４は置換もしくは無置換のアリール基、Ａｒ_１０、Ａｒ_１１、Ａｒ_１２は同一又は異なるアリレン基、Ｘ_１、Ｘ_２は置換もしくは無置換のエチレン基、又は置換もしくは無置換のビニレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

In the formula, R ₁₃ and R ₁₄ are substituted or unsubstituted aryl groups, Ar ₁₀ , Ar ₁₁ and Ar ₁₂ are the same or different arylene groups, X ₁ and X ₂ are substituted or unsubstituted ethylene groups, or substituted or unsubstituted Represents a substituted vinylene group. X, k, j, and n are the same as in the case of equation (1).

式中、Ｒ_１５、Ｒ_１６、Ｒ_１７、Ｒ_１８は置換もしくは無置換のアリール基、Ａｒ_１３、Ａｒ_１４、Ａｒ_１５、Ａｒ_１６は同一又は異なるアリレン基、Ｙ_１、Ｙ_２、Ｙ_３は単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表し同一であっても異なってもよい。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

In the formula, R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ , Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ , 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, or a vinylene group may be the same or different. X, k, j, and n are the same as in the case of equation (1).

式中、Ｒ_１９、Ｒ_２０は水素原子、置換もしくは無置換のアリール基を表し、Ｒ_１９とＲ_２０は環を形成していてもよい。Ａｒ_１７、Ａｒ_１８、Ａｒ_１９は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

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).

式中、Ｒ_２１は置換もしくは無置換のアリール基、Ａｒ_２０、Ａｒ_２１、Ａｒ_２２、Ａｒ_２３は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

In the formula, R ₂₁ represents a substituted or unsubstituted aryl group, and Ar 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).

式中、Ｒ_２２、Ｒ_２３、Ｒ_２４、Ｒ_２５は置換もしくは無置換のアリール基、Ａｒ_２４、Ａｒ_２５、Ａｒ_２６、Ａｒ_２７、Ａｒ_２８は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

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

式中、Ｒ_２６、Ｒ_２７は置換もしくは無置換のアリール基、Ａｒ_２９、Ａｒ_３０、Ａｒ_３１は同一又は異なるアリレン基を表す。Ｘ、ｋ、ｊおよびｎは、（１）式の場合と同じである。

In the formula, R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, and Ar ₂₉ , Ar ₃₀ and Ar ₃₁ represent the same or different arylene groups. X, k, j, and n are the same as in the case of equation (1).

  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 a plasticizer for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is suitably about 0 to 30% with respect to the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% is appropriate.

  Next, the case where the photosensitive layer has a single layer structure 33 will be described. A photoreceptor in which a pigment prepared by the above-described specific method is dispersed in a binder resin can be used. Single-layer photosensitive layers consist of a coating solution in which a charge generating substance, a charge transporting substance, and a binder resin are dispersed with a disperser using a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane. It can be formed by coating with a coat. The thickness of the single photosensitive layer is suitably about 5 to 100 μm. Further, the photosensitive layer may be a function separation type to which the above-described charge transport material is added, and can be used satisfactorily. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

  As the binder resin, the binder resin previously mentioned in the charge transport layer 37 may be used as it is, or the binder resin mentioned in the charge generation layer 35 may be mixed and used. Of course, the polymer charge transport materials mentioned above can also be used favorably. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight.

  In the electrophotographic photosensitive member of the present invention, an undercoat layer can be provided between the conductive support 31 and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin.

  Further, a metal oxide fine powder pigment exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moire and reduce residual potential.

These undercoat layers can be formed using an appropriate solvent and coating method as in the above-described 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, in the undercoat layer of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic matter such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

  In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. Materials used for the protective layer include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, Polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, poly Examples of the resin include vinylidene chloride and epoxy resin. In addition to the protective layer, fluorine resins such as polytetrafluoroethylene, silicone resins, and those resins dispersed with inorganic materials such as titanium oxide, tin oxide, potassium titanate, etc. for the purpose of improving wear resistance, etc. Can be added.

  As a method for forming the protective layer, a normal coating method is employed. In addition, about 0.1-10 micrometers is suitable for the thickness of a protective layer. In addition to the above, a known material such as a-C or a-SiC formed by a vacuum thin film forming method can be used as the protective layer.

  In the present invention, an intermediate layer may be provided between the photosensitive layer and the protective layer. In the intermediate layer, a binder resin is generally used 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, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.

  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 view for explaining the electrophotographic process and the electrophotographic apparatus of the present invention, and the following modifications also belong to the category of the present invention.

  In FIG. 4, the photosensitive member 1 has a pigment solid content concentration in a wet cake containing a solvent, on the conductive support, from which the pigment is taken out from at least the state in contact with the solvent as a final step of producing a pigment as a charge generating material. A photosensitive layer mainly composed of an organic pigment obtained by heating and drying at a temperature of room temperature or higher in a state of 75% or higher is provided.

  The photosensitive member 1 has a drum shape, but may be a sheet shape or an endless belt shape. For the charging charger 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13, known means such as a corotron, a scorotron, a solid state charger, and a charging roller are used. It is done.

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

  The light source such as the image exposure unit 5 and the charge removal lamp 2 emits light such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). All things can be used. Various types of 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 to irradiate only light in a desired wavelength range. Such a light source or the like irradiates the photosensitive member with light by providing a transfer process, a static elimination process, a cleaning process, or a pre-exposure process using light irradiation in addition to the process shown in FIG.

  The toner developed on the photoreceptor 1 by the developing unit 6 is transferred to the transfer paper 9, but not all is transferred, and some toner remains on the photoreceptor 1. Such toner is removed from the photoreceptor 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. When this is developed with negative (positive) polarity toner (electrodetection fine particles), a positive image can be obtained, and when developed with positive (negative) polarity toner, a negative image can be obtained. A known method is applied to the developing unit, and a known method is also used for the charge eliminating unit.

  FIG. 5 shows another example of the electrophotographic process according to the present invention. The photosensitive member 21 is a state in which the pigment is taken out from at least the state in contact with the solvent as a charge generation material on the conductive support and the pigment solid content concentration in the wet cake containing the solvent is 75% or more on the conductive support. And a photosensitive layer mainly composed of an organic pigment heated and dried at a temperature of room temperature or higher, driven by driving rollers 22a and 22b, charged by a charger 23, image exposure by a light source 24, and development (not shown). 1), transfer using the charger 25, exposure before cleaning with the light source 26, cleaning with the brush 27, and static elimination with the light source 28 are repeated. In FIG. 5, the photoconductor 21 (of course, the support is translucent in this case) is irradiated with pre-cleaning exposure light from the support side.

  The above illustrated electrophotographic process is illustrative of an embodiment of the present invention, and of course other embodiments are 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 image exposure and neutralization light irradiation may be performed from the support side.

  On the other hand, the light irradiation process is illustrated as image exposure, pre-cleaning exposure, and static elimination exposure. In addition, a pre-transfer exposure, a pre-exposure of image exposure, and other known light irradiation processes are provided to light the photosensitive member. Irradiation can also be performed.

  The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. A process cartridge is a single device (part) that contains a photosensitive member and includes a charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit. There are many shapes and the like of the process cartridge, but a general example is shown in FIG. The photosensitive member 16 has a pigment solid content concentration of 75% or more in a wet cake containing the solvent, on the conductive support, in which the pigment is taken out from at least the state in contact with the solvent as a final step of producing the pigment as a charge generating material. In this state, the photosensitive layer is composed mainly of an organic pigment obtained by heating and drying at a temperature of room temperature or higher.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not restrict | limited by these Examples. All parts are parts by weight.

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

(Example 1)
292 parts of 1,3-diiminoisoindoline and 1800 parts of sulfolane are mixed, and 204 parts of titanium tetrabutoxide are 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 completion of the reaction, the mixture was allowed to cool, and then the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, further washed several times with hot water at 80 ° C., and dried. Crude titanyl phthalocyanine was obtained. 60 parts of the obtained crude titanyl phthalocyanine pigment washed with hot water were stirred and dissolved in 1000 parts of 96% sulfuric acid at 3 to 5 ° C. and filtered. The obtained sulfuric acid solution was added dropwise to 35000 parts of ice water with stirring, the precipitated crystals were filtered, and then washed with water until the washing solution became neutral to obtain an aqueous paste of titanyl phthalocyanine pigment. 1,500 parts of 1,2-dichloroethane was added to 500 parts of this water paste, and the mixture was stirred at room temperature for 2 hours. Then, 2500 parts of methanol was further added and stirred and filtered. This was washed with methanol to obtain 98 parts of a pigment wet cake (solid content concentration of the wet cake was 76% by weight). Of these, 50 parts were dried at 70 ° C. in the air (1.0 × 10 ⁵ Pa) to obtain 38 parts of a titanyl phthalocyanine pigment.

(Example 2)
50 parts of pigment wet cake prepared in the same manner as in Example 1 (wet cake solid content concentration 76%) was dried under reduced pressure (1.33 × 10 ³ Pa) at 70 ° C. to obtain 24 parts of titanyl phthalocyanine pigment. 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) to obtain a titanyl phthalocyanine pigment in the same manner.

(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. To 250 parts of this water paste, 750 parts of 1,2-dichloroethane was added and stirred at room temperature for 2 hours, and then 1250 parts of methanol was further added and stirred and filtered. This was washed with methanol to obtain 98 parts of a wet cake of pigment (solid content concentration of wet cake 60% by weight). Of these, 50 parts were dried at 70 ° C. under reduced pressure (1.33 × 10 ³ Pa) to obtain 30 parts of a titanyl phthalocyanine pigment.

The pigments obtained in Examples 1 to 3 and Comparative Example 1 were coarsely pulverized using a commercially available mixer. The coarsely pulverized pigment was classified using a 300 mesh sieve to obtain a 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 spectrum, the X-ray diffraction spectrum of the pigment obtained in Example 3 is shown in FIG. 7 as a representative example. . It can be seen that the obtained titanyl phthalocyanine pigment has a desired crystal form with a maximum diffraction peak at a Bragg angle 2θ of 27.2 ± 0.2 °.

  Further, these pigments were immersed in 2-butanone, and a one-week storage test was conducted. In the method, 1 part of each pigment is put in 30 parts of 2-butanone and shaken, and then stored in a dark place for 1 week. After one month, each pigment was filtered and vacuum dried at 70 ° C. to obtain a dried pigment powder. Each was measured for X-ray diffraction spectra under the same conditions as described above. As a result, the pigments obtained in Examples 1 to 3 showed the same spectrum as that shown in FIG. 7, but the pigment prepared in Comparative Example 1 showed the X-ray diffraction spectrum shown in FIG. It can be seen that changes.

Example 4
A dispersion having the following composition was prepared by bead milling under the conditions shown below (this is referred to as Dispersion 1).
Titanyl phthalocyanine powder prepared in Example 1 10 parts polyvinyl butyral 10 parts methyl ethyl ketone 80 parts A commercially available bead mill disperser was charged with 1 mm diameter PSZ balls, all of methyl ethyl ketone and pigment dissolved with polyvinyl butyral were added, and the rotor rotation speed was 1000 r. Dispersed for 20 minutes at pm.

(Example 5)
A dispersion having the following composition was prepared by bead milling under the same conditions as in Example 4 (this is referred to as Dispersion 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 by bead milling under the same conditions as in Example 4 (this is referred to as Dispersion 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 A commercially available bead mill disperser was charged with 1 mm diameter PSZ balls, all of methyl ethyl ketone and pigment dissolved in polyvinyl butyral were charged, and the rotor rotation speed was 1000 r. pm. And dispersed for 5 minutes.

(Comparative Example 3)
A dispersion having the following composition was prepared by bead milling under the same conditions as in Example 4 (this is referred to as Dispersion 5).
10 parts of titanyl phthalocyanine powder prepared in Comparative Example 1 10 parts of polyvinyl butyral 80 parts of methyl ethyl ketone

  The pigment particle sizes in the dispersions prepared in Examples 4 to 6 and Comparative Examples 2 to 3 were measured with HORIBA, Ltd .: CAPA700 (centrifugal automatic particle size distribution analyzer). Further, when the prepared dispersion was solidified and powdered, the X-ray diffraction spectrum was measured in the same manner as described above, and the same X-ray diffraction spectrum as that of the titanyl phthalocyanine pigment obtained in Example 3 was obtained. . 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 produced in Examples 4 to 6 are fine dispersions and have a stable crystal form.

(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 composition on the electroformed nickel belt were sequentially applied and dried to prepare a laminated photoreceptor.
[Undercoat layer coating solution]
Titanium dioxide powder 15 parts Alcohol-soluble nylon 6 parts Ethanol 150 parts [Charge generation layer coating solution]
The aforementioned dispersions 1, 2, 3, and 5 were used, respectively.
[Charge transport layer coating solution]
Polycarbonate 10 parts Charge transport material of the following structural formula 7 parts

塩化メチレン ８０部

80 parts of methylene chloride

  The electrophotographic photosensitive member thus formed is mounted on the electrophotographic process shown in FIG. 5 (no exposure before cleaning), and the image exposure light source is a 780 nm semiconductor laser (image writing by a polygon mirror). A surface potential meter probe was inserted so that the surface potential of the photoconductor could be measured. 7000 sheets were continuously printed, and the surface potentials of the image exposed area and the image non-exposed area at that time were measured initially and after 7000 sheets. The results are shown in Table 2. From Table 2, it can be seen that the electrophotographic photoreceptors of Examples 7 to 9 maintain a stable surface potential even after repeated use. In particular, it can be seen that the photoreceptor of Example 9 has a stable surface potential even after repeated use.

(Examples 10 to 12 and Comparative Example 5)
The aluminum cylinder surface was anodized and then sealed. On top of this, the following charge generation layer coating solution and charge transport layer coating solution are 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 photographic photoreceptor was prepared.
[Charge generation layer coating solution]
The aforementioned dispersions 1 to 4 were used, respectively.
[Charge transport layer coating solution]
8 parts of charge transport material of the following structural formula

ポリカーボネート １０部
塩化メチレン ８０部

Polycarbonate 10 parts Methylene chloride 80 parts

  The electrophotographic photoreceptor thus constructed was mounted on the electrophotographic process cartridge shown in FIG. 6 and then mounted on the image forming apparatus. However, the image exposure light source was a semiconductor laser of 780 nm (image writing by a polygon mirror). 5000 sheets were printed continuously, and the initial and 5000th images were evaluated. The results are shown in Table 3. From Table 3, it can be seen that when dispersions 5 to 7 are used (Examples 10 to 12), good images can be obtained at the initial stage and after repeated use.

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

塩化メチレン １００部

100 parts methylene chloride

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

塩化メチレン １００部

100 parts methylene chloride

  Each of the electrophotographic photosensitive members of Examples 10 and 13 to 14 described above was mounted on the electrophotographic process shown in FIG. 4 (however, the image exposure light source was an LD having a light emission at 780 nm), and 20,000 sheets were continuously formed. Printing was performed, and images at that time were evaluated after the initial and 20,000 sheets. Further, the change (decrease amount) in the thickness of the charge transport layer was measured. The results are shown in Table 4. From Table 4, it can be seen that the electrophotographic photoreceptors of Examples 13 to 14 exhibit particularly excellent wear resistance.

1 is a schematic cross-sectional view of an electrophotographic photosensitive member used in the present invention. FIG. 3 is a schematic cross-sectional view of another electrophotographic photosensitive member used in the present invention. FIG. 6 is a schematic cross-sectional view of still another electrophotographic photosensitive member used in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Schematic for demonstrating the electrophotographic process and electrophotographic apparatus of this invention. Schematic for demonstrating another electrophotographic process and electrophotographic apparatus of this invention. Schematic for demonstrating the typical process cartridge of this invention. The X-ray-diffraction spectrum of the titanyl phthalocyanine pigment obtained in Example 3. The X-ray diffraction spectrum after carrying out the storage test of the titanyl phthalocyanine pigment obtained by the comparative example 1 for one week. The X-ray-diffraction spectrum after carrying out the storage test of the titanyl phthalocyanine pigment obtained by the comparative example 3 for one week.

Explanation of symbols

31 Conductive Support 33 Monolayer Photosensitive Layer 35 Charge Generation Layer 37 Charge Transport Layer

Claims (7)

In the method for producing an organic pigment, in which the final step of producing the pigment is a step of taking out the pigment from a state in contact with the solvent, heating at a temperature of room temperature or higher with the pigment solid content concentration in the wet cake containing the solvent being 75% or higher A method for producing an organic pigment, which comprises drying. In the method for producing an organic pigment, in which the final step of producing the pigment is a step of taking out the pigment from a state in contact with the solvent, heating at a temperature of room temperature or higher with the pigment solid content concentration in the wet cake containing the solvent being 90% or higher A method for producing an organic pigment, which comprises drying. The method for producing an organic pigment according to claim 1 or 2, wherein the final step is a method for controlling the crystal form of the pigment. The said drying process is performed under the reduced pressure of 1.33 * 10 < ³ > Pa or less, The preparation methods of the organic pigment in any one of Claims 1-3 characterized by the above-mentioned. The method for producing an organic pigment according to any one of claims 1 to 4, wherein the organic pigment produced in the production method is a phthalocyanine pigment. The method for producing an organic pigment according to claim 1, wherein the organic pigment produced in the production method is titanyl phthalocyanine. The organic pigment produced in the production method is at least titanyl phthalocyanine having a Bragg angle 2θ maximum diffraction peak at 27.2 ± 0.2 ° with respect to the characteristic X-ray (wavelength 1.541 波長) of CuKα. A method for producing an organic pigment according to any one of claims 1 to 4.

Images