JP4262061B2 - Method for producing electrophotographic photosensitive member - Google Patents

Description

The present invention relates to a method for producing an electrophotographic photoreceptor.

  The electrophotographic process includes, for example, charging a photosensitive member having at least a photosensitive layer on a conductive support, formation of a latent image by exposure, formation of a developed image by toner, transfer to a transfer material mainly composed of paper, and The transfer residual toner is removed (cleaned) / collected. The electrophotographic photosensitive member used here is required to have required sensitivity, electrical characteristics, and optical characteristics according to the applied electrophotographic process. Furthermore, the surface layer of the photoreceptor to be used repeatedly is directly subjected to electrical and mechanical external forces such as charging, toner development, transfer to paper, and cleaning of residual toner. Is done. Specifically, when using a charging method that involves scratches and wear due to rubbing, or discharge, resistance to chemical degradation caused by ozone or NOx generated under high humidity is required. Further, when the remaining toner is repeatedly cleaned, there are problems such as toner adhesion to the surface of the photoconductor and turning of the blade when performing blade cleaning. Therefore, characteristics such as surface slipperiness, releasability, and contamination resistance are required. The

  In order to meet such demands, the surface layer material of the photoreceptor is a resin having excellent releasability and slipperiness such as a fluorine resin, silicone resin, urethane resin, unsaturated ester material, etc. It has been widely proposed to use a high hardness resin material represented by

  However, no material has yet been found that satisfies the various characteristics described above. For example, the fluororesin alone has a low hardness and it is difficult to suppress the occurrence of scratches, and furthermore, it is difficult to form a film because it is hardly soluble in general solvents.

  On the other hand, examples have been reported in which a material having a high hardness such as a curable silicone resin utilizing the high reactivity of alkoxysilane is used for the photoreceptor, but these resins are slippery and have an electrical property under high humidity. It was not sufficient in terms of characteristics or releasability. Furthermore, since these curable materials are highly reactive with hydroxyl groups, there are restrictions on the solvent used to apply the photosensitive layer, and the curing reaction proceeds gradually due to the influence of moisture, which makes the coating solution stable. There was also a problem in terms of productivity of the photoreceptor.

In addition, for example, a material that forms a cured film using unsaturated bond cleavage , such as a prepolymer of diallyl phthalate resin, is generally radically polymerizable, and a coating solution using this material is resistant to moisture. On the other hand, although it is comparatively stable, insulation resistance, etc. due to poor curing on the film surface due to the polymerization inhibition effect by oxygen in the air, and when a photoinitiator is used, the carbon-carbon bond breakage reaction due to light irradiation. Only cured products with unstable electrical properties can be obtained. Therefore, there are problems such as a decrease in transfer efficiency due to an increase in surface free energy and an image blur due to moisture absorption.

On the other hand, the material used for the surface layer of the photoconductor is not limited to the above-mentioned surface properties such as hardness, rubbing resistance and slipperiness, and the movement of charge is not delayed in the uppermost surface layer. Electrical characteristics are required. Here, when the surface layer does not have a function of moving charges, charge is accumulated in the photosensitive layer, and the electrophotographic process of charge-exposure is repeated, resulting in an increase in residual potential and degrading image quality . It will be.

  In order to solve this problem, a method of incorporating a charge transport material in the surface layer has been proposed. For example, when curing is performed by adding a charge transport material to alkoxysilanes, the charge transport material and the siloxane component are often poorly compatible, and also includes a highly polar unit such as a urethane resin. When a charge transport material is contained in the resin, the charge mobility due to the charge transport material is reduced, and satisfactory electrophotographic characteristics cannot be obtained.

  Further, in thermosetting resins, it is not sufficient to perform heat treatment alone, and various materials to which a curing catalyst such as a curing accelerator and a polymerization initiator must be added are found. However, if such a curing catalyst remains in the cured film, there is a possibility that even if it is a very small amount, the movement of electric charge may be hindered or the electrical resistance of the cured film may be reduced. . On the other hand, paints to which a curing catalyst is added tend to gradually react even at room temperature, resulting in poor paint stability and the disadvantage of making it difficult to produce and store paints in large quantities. .

  In addition, as a charging method for the electrophotographic photosensitive member, a method involving discharge is the mainstream, but among them, in the contact charging method, both a DC voltage and an AC voltage are superimposed on the charging member, and the electrophotographic photosensitive member and the charging member are superposed. The method of charging with a slight gap between the surface and the surface of the electrophotographic photoreceptor due to oxidative degradation is observed due to the discharge energy, although the charging stability is excellent. The transfer efficiency decreases due to the increase in free energy. Further, when a curable resin is used, the amount of abrasion of the photosensitive layer is small, so that a substance destroyed due to oxidative degradation may cause a problem such as image blur due to moisture absorption.

  In general, when a surface layer is provided with a curable resin on a thermoplastic resin photosensitive layer, if the chemical composition is completely different from that of the lower photosensitive layer such as a fluororesin, the adhesion to the surface layer is improved. Unfortunately, when used for a long time in an electrophotographic process, a part of the photosensitive layer is peeled off, resulting in an image defect.

  In addition, when the crosslink density increases in some curable resins, the hardness increases, but at the same time, the brittleness also increases, and the surface roughness of the electrophotographic photosensitive member increases extremely during long-term use, causing problems on the image. In reality, no satisfactory material has been obtained for adapting the curable resin to the surface layer.

  Further, Patent Document 1 and the like disclose examples in which a charge transport material containing a phenolic hydroxyl group or a hydroxyalkyl group is contained in the surface layer of the photoreceptor, but these photoreceptors still have high durability in recent years. However, it is not in response to the demands for high productivity and high image quality, and the actual situation is that the mechanical strength, residual potential, productivity, etc. are not fully satisfied.

Patent Document 2 discloses that an electrophotographic photosensitive member having a protective layer containing a resol-type phenol resin and metal particles or metal oxide particles on a photosensitive layer remains in a low-humidity environment. There is almost no increase in potential, high-quality images with no image blur and flow in high-temperature environments, excellent releasability, and excellent durability against wear and scratches. Is disclosed.
Japanese Patent Laid-Open No. 10-228126 JP 2002-82466 A

An object of the present invention is to provide an electrophotographic photosensitive member having a surface layer that has excellent wear resistance without causing addition of a curable catalyst, has a hardness that does not cause scratches, etc., and does not reduce the charge transport properties inherent to the photosensitive member. It is to provide a manufacturing method . Furthermore, this invention is providing the manufacturing method of the electrophotographic photoreceptor which has a surface layer which can be apply | coated with high productivity. Another object of the present invention is to provide a method for producing a high-quality electrophotographic photoreceptor that has good adhesion to the lower layer and exhibits excellent resistance to discharge deterioration .

According to the present invention, there is provided a process for producing an electrophotographic photosensitive member having a photosensitive layer on an electroconductive substrate, the phenolic hydroxyl groups of Les Orres type phenolic resin, the epoxy compound having two or more epoxy groups in the molecule and epoxy-modified phenolic resins obtained by the Rukoto by adding an epoxy group, the charge transport material and the either or both of the conductive fine particles, a coating film of paint for forming a surface layer that contains There is provided a method for producing an electrophotographic photoreceptor, comprising a step of curing to form a surface layer of the electrophotographic photoreceptor.

By using the surface layer of the present invention, it has a surface layer that is excellent in adhesion and wear resistance, has hardness and toughness that do not cause scratches, etc., and does not deteriorate the charge transport property inherent to the photoreceptor. An electrophotographic photoreceptor can be provided. Furthermore, the surface layer of the present invention can be applied with high productivity, and mass production of electrophotographic photoreceptors having high durability, high stability, and high image quality becomes possible .

Hereinafter, embodiments of the present invention will be described in detail.
As a result of intensive studies, the present inventors have found that an electrophotographic photosensitive member having a surface layer containing a crosslinked product of an epoxy-modified phenol resin having a specific structure and at least one of a charge transport material and conductive fine particles. I have come to find that my body can solve the above problems.

  The epoxy-modified phenol resin according to the present invention is obtained by adding an epoxy group to the phenolic hydroxyl group of a resol type phenol resin. Here, the resol type phenolic resin is a compound obtained by addition / condensation reaction of a compound having a phenolic hydroxyl group and an aldehyde under an alkali catalyst, and the hydroxymethyl group produced when formaldehyde is added to the phenol ring. Reactive crosslinking group. Examples of the compound having a phenolic hydroxyl group include phenol, cresol, xylenol, paraalkylphenol, paraphenylphenol, resorcin, and bisphenol. Examples of aldehydes include formaldehyde, paraformaldehyde, furfural, acetaldehyde and the like.

The epoxy-modified of the phenolic hydroxyl group of resol-type phenolic resin, upon resol reaction of the compound and an aldehyde having a phenolic hydroxyl group under alkaline conditions, by mixing a compound having an epoxy ring in the reaction system, a phenol This can be carried out by a method in which an addition hydroxyl group and an epoxy ring are reacted . A resin in which the phenolic hydroxyl group of such a resol type phenol resin is modified with an epoxy group is subjected to a heat treatment of about 130 ° C. to 170 ° C., whereby an ether bond or a further condensation reaction is caused by a condensation reaction between hydroxymethyl groups. To form a methylene bond, or to form a methylene bond by a condensation reaction between a hydroxymethyl group and a hydrogen atom at the ortho-position or para-position of a phenolic hydroxyl group. These condensation reactions may occur between various molecules. As a result, a three-dimensional cured film having a high crosslinking density can be obtained. These condensation reactions are essentially reactions that are not hindered by moisture and oxygen in the air, and proceed sufficiently even in a system to which a charge transport material is added. The crosslinking reaction by heat treatment of the epoxy-modified phenolic resin has a feature that it is not particularly necessary to add a curing catalyst generally used for thermosetting. Therefore, when the compound according to the present invention is used for the surface layer of the electrophotographic photoreceptor, problems such as an increase in residual potential and a decrease in resistance of the surface layer due to the residual curing catalyst do not occur.

  In addition, the epoxy-modified resol type phenol resin of the present invention is obtained by adding an epoxy group to the phenolic hydroxyl group of the resol type phenol resin, and is not simply a blend of a phenol resin and an epoxy resin. Since the epoxy resin and the phenol resin are in a main agent-curing agent relationship, the curing reaction proceeds gradually only by blending, and the pot life is shortened. On the other hand, those blended with a slow-reaction epoxy resin-phenolic resin combination are also slow to cure by heating, and in order to obtain sufficient hardness, heating is required to significantly impair the characteristics of the photoreceptor. According to such an epoxy-modified phenol resin, since the reaction between the epoxy group and the phenolic hydroxyl group is completed in advance, the heat treatment that causes such pot life and thermal deterioration is released.

  In addition, since the epoxy-modified phenolic resin according to the present invention can be crosslinked by heating, there is no need to add a curing catalyst, and the hydroxymethyl group itself is different from isocyanate and silicone resin, and has stability against moisture. It was found that the coating solution was excellent in stability because it was sufficient.

  Moreover, regarding the epoxy-modified phenol resin according to the present invention, when the phenolic hydroxyl group is modified with, for example, an epoxy group represented by the following formulas (1) or (2), the following formulas (3) and (4) It has an ether bond as shown in FIG. Further, in addition to the ether bond, the epoxy-modified phenol resin according to the present invention is present due to the presence of a highly flexible bond group such as an alkylene bond, a cycloalkylene bond, and an ester bond in the skeleton of the epoxy compound used when modified. Alternatively, the crosslinked product is provided with flexibility and flexibility and toughness in addition to the excellent film strength possessed by a normal curable phenol resin. Furthermore, it is possible to improve the adhesion to the adherend, which is a feature of the epoxy resin.

  In the present invention, examples of the compound containing an epoxy group used for modification of the phenolic hydroxyl group include epoxy compounds represented by the following structural formulas [Chemical Formula 5] to [Chemical Formula 30]. In particular, by using a polyfunctional epoxy compound, the hardness of the surface layer after film formation and curing can be further increased.

  The proportion of these epoxy compounds added to the phenolic hydroxyl group of the resol-type phenolic resin affects the film strength after curing and the resistance to discharge deterioration. Therefore, it depends on the usage environment of the electrophotographic photoreceptor and the required durability life. However, it is possible to add an epoxy group in a proportion of 3 to 70%, preferably 5 to 50%, more preferably 7 to 25% with respect to the phenolic hydroxyl group of the resol type phenol resin. It is.

  Moreover, the epoxy-modified phenol resin according to the present invention can have a structure that does not contain hetero atoms other than oxygen. In the combination of the epoxy-modified phenolic resin having this composition and the charge transporting material, the charge transporting ability is hardly hindered, so that particularly excellent electrophotographic characteristics can be obtained.

  The layer constituting the outermost surface of the electrophotographic photosensitive member according to the present invention, that is, the surface layer, may contain at least one selected from a charge transport material and conductive fine particles in order to cause the movement of charges without delay. preferable. The structure of the charge transport material is preferably modified with a hydroxy group in view of compatibility with the epoxy-modified phenol resin. The hydroxy group is suitably a hydroxyalkyl group, a hydroxyalkoxy group or a phenolic hydroxyl group.

  Here, when the hydroxy group that modifies the charge transporting substance is a hydroxyalkyl group or a hydroxyalkoxy group, the solubility in a solvent can also be improved, so that the charge transporting ability in the surface layer is maintained at a high level. Is possible. In particular, the number of carbon atoms in the alkyl chain of these hydroxyalkyl groups and hydroxyalkoxy groups is preferably from 1 to 8, more preferably from 1 to 5, in view of operability and solubility in the synthesis of these charge transport materials.

  In addition, when the hydroxy group that modifies the charge transport material is a phenolic hydroxyl group, it can also react with the ortho- or para-position hydrogen atom of the phenolic hydroxyl group in the condensation reaction process of the polyhydroxymethylated bisphenol compound described above. For this reason, the cross-linking reaction occurs even in the case of the bisphenol compound and the charge transport material, and it is possible to bring out a synergistic effect characteristic that the strength of the formed surface layer is further improved.

  Specific examples of the charge transport material (CTM) containing a hydroxy group that can be used in the present invention are illustrated below, but the present invention is not limited only to these compounds.

  Examples of conductive fine particles that can be used in the present invention include, for example, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, graphite, carbon black, tin oxide doped with indium, and antimony doped. It is possible to select from conventionally known materials such as tin oxide and zirconium oxide. These conductive particles can be used alone or in combination of two or more.

  As a solvent for preparing a coating material for forming the surface layer, the epoxy-modified phenolic resin according to the present invention, further dissolves the charge transport substance well, and further, a lower layer constituting a surface to which the coating material of the surface layer is applied, For example, a solvent that does not adversely affect the charge transport layer, the charge generation layer, and the like is preferable.

  Therefore, as solvents, alcohols such as methanol, ethanol and 2-propanol, ketones such as acetone, cyclohexanone and MEK, esters such as methyl acetate and ethyl acetate, ethers such as tetrahydrofuran and dioxane, toluene, xylene and the like Aromatic hydrocarbons, halogen-based hydrocarbons such as chlorobenzene and dichloromethane can be used, and these may be used in combination.

  Among these, the most suitable solvent for the form of the phenol resin is alcohols such as methanol, ethanol, and 2-propanol.

  Conventionally known charge transport materials are generally insoluble or hardly soluble in alcohol solvents, and uniform dissolution in the epoxy-modified phenolic resin of the present invention is difficult, but they contain a hydroxy group as a charge transport material. In some cases, it is soluble in a solvent containing alcohol as a main component, and there is little damage to the lower layer such as a charge transport layer.

  As a method for applying the surface layer, general coating methods such as a dip coating method, a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method and a blade coating method can be used.

  In the present invention, an antioxidant additive may be added to the surface layer for the purpose of preventing deterioration of the surface layer due to adhesion of active substances such as ozone and NOx generated during charging.

  Next, the configuration of the electrophotographic photoreceptor according to the present invention will be described below.

  The electrophotographic photoreceptor according to the present invention preferably has mainly a laminated structure. In the electrophotographic photosensitive member of FIG. 1a, a charge generation layer 3 and a charge transport layer 2 are provided in this order on a conductive support 4, and further a curable charge transport type surface layer 1 of the present invention is provided.

  Further, as shown in FIGS. 1 b and 1 c, a binder layer 5 and an undercoat layer 6 for preventing interference fringes may be provided between the conductive support 4 and the charge generation layer 3.

  In FIG. 1 d, the charge generation layer 3 is provided in order on the conductive support 4, and the curable charge transport type surface layer 1 of the present invention is provided directly on the charge generation layer 3. It is an example. That is, an embodiment in which the charge transport layer constitutes a surface layer is shown.

  Although it depends on the layer structure of the photoconductor, the thickness of the surface layer should be set to an appropriate thickness in order to improve the durability of the photoconductor and suppress the increase in residual potential due to the provision of the surface layer. Is preferred. Specifically, for example, when the surface layer 1 is provided on the charge transport layer 2 as shown in FIGS. 1A, 1B, and 1C, a range of 0.1 μm to 10 μm, particularly a range of 0.5 μm to 7 μm. Is preferred. Further, when the surface layer 1 as a charge transport layer is provided directly on the charge generation layer 3 as shown in FIG. 1D, the range of 3 μm to 40 μm, particularly the range of 8 μm to 20 μm is preferable.

  As the conductive support 4, it is possible to use a conductive support itself, for example, aluminum, aluminum alloy, stainless steel, etc. In addition, aluminum, aluminum alloy, indium oxide-tin oxide alloy, etc. are vacuumed. The conductive support having a layer formed by vapor deposition, a plastic, a support obtained by impregnating plastic or paper with a suitable binder with conductive fine particles (for example, carbon black, tin oxide, titanium oxide, silver particles, etc.), A plastic having a conductive binder can be used.

  In addition, a binder layer (adhesive layer) having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer.

  The binder layer is formed to improve the adhesion of the photosensitive layer, improve coating properties, protect the support, cover defects on the support, improve charge injection from the support, and protect against electrical breakdown of the photosensitive layer. Is done. The binder layer can be formed of casein, polyvinyl alcohol, ethyl cellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, aluminum oxide, or the like. The thickness of the binding layer is preferably 5 μm or less, and more preferably 0.1 to 3 μm.

  Examples of the charge generating material used in the present invention include (1) azo pigments such as monoazo, disazo and trisazo, (2) phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, and (3) indigo materials such as indigo and thioindigo. Pigments, (4) perylene pigments such as perylene anhydride and perylene imide, (5) polycyclic quinone pigments such as anthraquinone and pyrenequinone, (6) squarylium dyes, (7) pyrylium salts and thiapyrylium salts ( 8) Triphenylmethane dyes, (9) inorganic substances such as selenium, selenium-tellurium, amorphous silicon, (10) quinacridone pigments, (11) azulenium salt pigments, (12) cyanine dyes, (13) xanthene dyes, 14) quinoneimine dye, (15) styryl dye, (16) cadmium sulfide Such as arm and (17) zinc oxide.

  Examples of the binder resin used for the charge generation layer include polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, Examples include, but are not limited to, silicone resins, polysulfone resins, styrene-butadiene copolymer resins, alkyd resins, epoxy resins, urea resins, and vinyl chloride-vinyl acetate copolymer resins. These may be used alone, as a mixture or as a copolymer polymer, or one or more thereof.

  The solvent used for the coating for the charge generation layer is selected in consideration of the solubility and dispersion stability of the resin used and the charge generation material. As the organic solvent, alcohols, sulfoxides, ketones, ethers, esters , Aliphatic halogenated hydrocarbons or aromatic compounds can be used.

  The charge generation layer 3 is well dispersed by a method such as a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, and a roll mill together with the above-described charge generation material in a amount of 0.3 to 4 times the binder resin and solvent. It is formed by coating and drying. The thickness is preferably 5 μm or less, particularly in the range of 0.01 to 1 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers or known charge generating substances may be added to the charge generation layer 3 as necessary.

  The charge transport materials used are various triarylamine compounds, various hydrazone compounds, various styryl compounds, various stilbene compounds, various pyrazoline compounds, various oxazole compounds, various thiazole compounds, various triarylmethane compounds. Etc.

  Examples of the binder resin used to form the charge transport layer 2 include acrylic resin, styrene resin, polyester, polycarbonate resin, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin, and unsaturated resin. A resin selected from resins and the like is preferable. Particularly preferred resins include polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, polycarbonate resin or diallyl phthalate resin.

  The charge transport layer 2 is generally formed by dissolving the charge transport material and the binder resin in a solvent and applying them. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 2. Solvents include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, and chlorinated hydrocarbons such as chlorobenzene, chloroform and carbon tetrachloride. . When applying this solution, for example, a coating method such as a dip coating method, a spray coating method, or a spinner coating method can be used, and drying is performed at a temperature in the range of 10 ° C. to 200 ° C., preferably 20 ° C. to 150 ° C. It can be carried out under blast drying or static drying at a temperature of 5 minutes to 5 hours, preferably 10 minutes to 2 hours.

  The charge transport layer 2 is electrically connected to the above-described charge generation layer, receives the charge carriers injected from the charge generation layer in the presence of an electric field, and transfers these charge carriers to the interface with the protective layer. Has the function of transporting. Since this charge transport layer has a limit to transport charge carriers, the film thickness cannot be increased more than necessary, but a range of 5 to 40 μm, particularly 7 to 30 μm is preferable.

  Furthermore, an antioxidant, a UV absorber, a plasticizer, or a known charge transport material can be added to the charge transport layer 2 as necessary.

  In the present invention, the protective layer is coated on the charge transport layer and cured to form a film.

  A specific example of an electrophotographic apparatus using the electrophotographic photosensitive member of the present invention is shown in FIG. In this apparatus, a primary charging unit 3, an image exposure unit 4, a developing unit 5, and a transfer unit 6 are disposed on the peripheral surface of the electrophotographic photosensitive member 1.

  In the image forming method, first, a voltage is applied to the primary charging unit 3 to charge the surface of the photoconductor 1, and an image corresponding to the original is image-exposed on the surface of the photoconductor 1 by the image exposure unit 4, thereby electrostatic latent image Form. Next, the electrostatic latent image on the photosensitive member 1 is developed (visible increase) by attaching the toner in the developing unit 5 to the photosensitive member 1. Further, the toner image formed on the photoconductor 1 is transferred onto a transfer material 7 such as paper supplied by a transfer means 6, and the remaining toner remaining on the photoconductor 1 without being transferred to the transfer material is cleaned. Collect at 9 mag. In recent years, a cleaner-less system has been studied, and the residual toner can be directly collected by a developing device or the like. Further, after the charge removal process is performed by the pre-exposure from the pre-exposure unit 10, it is repeatedly used for image formation. Note that the pre-exposure means is not always necessary.

  In this image forming apparatus, a halogen light, a fluorescent lamp, a laser beam, an LED, or the like can be used as a light source of the image exposure unit 4. Moreover, you may add another auxiliary | assistant process as needed.

  In the present invention, the above-described photosensitive member 1 and a plurality of constituent elements such as the primary charging unit 3, the developing unit 5, and the cleaning unit 9 are integrally coupled as a process cartridge. You may comprise so that attachment or detachment with respect to electrophotographic apparatus main bodies, such as a copying machine and a printer, is possible. For example, a process in which at least one of the primary charging unit 3, the developing unit 5, and the cleaning unit 9 is integrally supported together with the photoreceptor 1 to form a cartridge and can be attached to and detached from the apparatus main body using guide means such as the rail 12 of the apparatus main body. The cartridge 11 can be obtained. Further, when the electrophotographic apparatus is a copying machine or a printer, the image exposure means 4 uses reflected light or transmitted light from a document, or converts a signalized document into a laser beam that is performed according to this signal. Light emitted by scanning, LED array driving, liquid crystal shutter array driving, and the like.

  Next, an example explains the present invention. However, embodiments of the present invention are not limited to these.

  Using an aluminum cylinder (JIS A3003 aluminum alloy) having a length of 260.5 mm and a diameter of 30 mm as a support, a 5% by mass methanol solution of polyamide resin (trade name: Amilan CM8000, manufactured by Toray) was applied thereon by a dipping method. A subbing layer of 0.5 μm was provided.

  Next, a crystal form having strong peaks at 9.6 and 27.2 ° with a diffraction angle of 2θ ± 0.2 ° in the X-ray diffraction spectrum of CuKα represented by the following structural formula [Chemical Formula 44] as a charge generation material. 4 parts of oxytitanium phthalocyanine pigment (parts by mass, the same applies hereinafter)

2 parts of polyvinyl butyral resin BX-1 (manufactured by Sekisui Chemical Co., Ltd.) and 110 parts of cyclohexanone were dispersed in a sand mill with φ1 mm glass beads for 4.5 hours. Thereafter, it was diluted with 130 parts of ethyl acetate to obtain a charge generation layer coating material.
The dispersion was applied onto the previous undercoat layer by a dipping method to form a 0.18 μm charge generation layer.

Next, 7.5 parts of a charge transport material having the following structural formula [Chemical Formula 45],

And 10 parts of bisphenol Z-type polycarbonate (trade name: Z-200, manufactured by Mitsubishi Gas Chemical) was dissolved in 60 parts of monochlorobenzene and 20 parts of dichloromethane. This solution was dip-coated on the charge generation layer and dried with hot air at 115 ° C. for 50 minutes to form a 20 μm charge transport layer.

  Next, an epoxy obtained by adding the epoxy compound of the exemplified compound [Chemical Formula 23] to 15% of the number of phenolic hydroxyl groups of the phenol / aldehyde resol type phenol resin as the binder resin prepolymer component of the surface layer 10 parts of the modified phenolic resin and 7 parts of the hydroxyl group-containing charge transport material represented by the exemplified compound No. 12 are dissolved in 40 parts of ethyl alcohol as a solvent to form a coating solution for the surface layer, and the charge transport layer A surface layer having a thickness of 3 μm was provided by dip coating on the substrate and drying with hot air at 155 ° C. for 1 hour. Here, the film thickness of the surface layer was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd.).

  In addition, the stability of the coating solution of the surface layer was good, and even when the coating solution was circulated for 20 days in an environment of a temperature of 23 ° C. and a humidity of 50%, no significant change in the liquid property was observed. .

  Further, adhesion evaluation between the surface layer and the lower layer was performed based on JISK 5400. As a result, there was no problem with respect to the adhesion between the surface layer and the lower charge transport layer in the photoreceptor.

The electrophotographic characteristics were evaluated by attaching to a laser beam printer (trade name: LBP-NX: manufactured by Canon Inc.). The laser beam printer was modified so that the electrophotographic sensitivity of the mounted electrophotographic photosensitive member was charged so that the dark portion potential was −700 (V). Then, the amount of light necessary to lower the potential of −675 (V) to −175 (V) is measured by irradiating the photosensitive member whose dark portion potential is set to −700 (V) with laser light having a wavelength of 780 (nm). The sensitivity of the electrophotographic photosensitive member was used. Furthermore, the potential when a light amount of 20 μJ / cm ² was irradiated was measured as a residual potential Vr.

  Further, the same laser beam printer was used to measure the amount of scraping after a durability test of 10,000 sheets and to compare the output image quality in an environment of temperature 30 ° C./humidity 80%.

In Example 1, the charge generating material is 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction and An electrophotographic photosensitive member was produced in the same manner except that the crystal type hydroxygallium phthalocyanine having a strong peak at 28.3 ° was used.

<Examples 3 to 10>
An electrophotographic photoreceptor was prepared in the same manner as in Example 2, except that the resin used for the surface layer was changed to an epoxy-modified resol type phenol resin obtained by using the epoxy compounds shown in Table 1 below.

<Examples 11 to 18>
An electrophotographic photoreceptor in the same manner as in Example 3 except that at least one selected from the surface layer thickness, the hydroxyl group-containing charge transport material , and the epoxy modification rate of the epoxy-modified resol type phenol resin is changed as shown in Table 1. Was made.

<Example 19>
The hydroxyl group-containing charge transporting material is exemplified by Compound No. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 33 was used.

<Comparative Example 1>
In Example 1, the novolak type phenolic resin (trade name: CMK-2400, manufactured by Showa Polymer Co., Ltd.) not subjected to epoxy modification was used as the resin for the surface layer . In place of Ex. A photoconductor was prepared in the same manner except that No. 16 was used.

<Comparative example 2>
In Example 1, the resin of the surface layer was changed to a resol type phenol resin (modification rate: 30%) modified with an epoxy compound of the exemplified compound [Chemical Formula 14], and the same procedure was performed except that the hydroxyl group-containing charge transport material was not contained. An electrophotographic photosensitive member was produced.

<Comparative Example 3>
In Example 2, the following structural formula

A coating solution is prepared by dissolving the exemplified compound No. 16 in 50 parts of methyl ethyl ketone as a charge transporting substance and 5 parts of a modified burette solution (solid content: 67% by mass) represented by the following formula: spray coating on the charge transporting layer It was applied by the method, dried at room temperature for 5 minutes, and then heated at 155 ° C. for 60 minutes to form a surface layer having a thickness of 3 μm. The mixing ratio of this coating solution was adjusted so that [total number of moles of hydroxy groups of Exemplified Compound 16]: [total number of moles of isocyanate groups of Chemical Formula 46] was about 47:53.

<Comparative example 4>
In Comparative Example 1, as a resin for the surface layer, 7 parts of a novolak type phenol resin (trade name: CMK-2400, manufactured by Showa Polymer Co., Ltd.) not subjected to epoxy modification and 3 parts of the following epoxy compound [Chemical Formula 47] An electrophotographic photoreceptor was prepared in the same manner except that the simple blend material was used.

<Comparative Example 5>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface layer was not provided.

<Comparative Example 6>
A photoconductor was prepared in the same manner as in Example 19 except that the epoxy-modified resol type phenol resin was replaced with an alkali resol type phenol resin (manufactured by Asahi Organic Materials Co., Ltd., HP-8300).

  The protective layer configurations of Examples 1 to 19 and Comparative Examples 1 to 6 are summarized in Table 1.

Surface layer configurations of Examples 1 to 19 and Comparative Examples 1 to 6 These electrophotographic photoreceptors and coatings for the surface layer were evaluated by the same test method as described in Example 1. Adhesion between surface layer and photosensitive layer, stability of surface layer coating, sensitivity as electrophotographic photoreceptor, image quality after durability test by laser beam printer in environment of temperature 30 ° C / humidity 80%, per 10,000 sheets The amount of wear of the surface layer was compared, and the evaluation results are summarized in Table 2.

The evaluation of adhesion and paint stability was performed according to the following criteria.
Adhesiveness: As a result of evaluation based on the coating adhesion evaluation method (cross-cut method) defined in JIS K 5400 (corresponding to ISO 2409: 1992),
○: No peeling of the film was observed.
(Circle) (triangle | delta): The area of the film peeling part was less than 10% of the whole.
X: The area of the peeling part of the film was 10% or more of the whole.
Paint stability:
○: In the paint circulation test for 20 days, no changes were observed after 20 days with respect to the viscosity change, gelation, aggregation, sedimentation, and turbidity of the paint.
○ △: In 20 days of paint circulation test, some changes were observed after 20 days in terms of viscosity change, gelation, aggregation, sedimentation, and turbidity of the paint, but it had a significant effect on the coatability of the surface layer. Was not affected.
X: In a paint circulation test for 20 days, changes in viscosity, gelation, aggregation, sedimentation, and turbidity of the paint are observed after 20 days, which is the coatability of the surface layer , or the surface layer after coating. The membrane condition was affected.

From the evaluation results of these results of Examples 1 to 19 and Comparative Examples 1 to 6, if the resin of the present invention is used as a table surface layer it may not observed significant decrease in sensitivity as an electrophotographic photoreceptor, the electrophotographic process It is possible to remarkably improve the durability strength inside. Furthermore, it is possible to maintain sufficient adhesion with the lower charge transport layer. Also, when using a resin of the present invention to prepare a coating material for the front surface layer, there is plenty also the paint stability, it has been found that not any disturb even in continuous production.

<Example 20>
A photoconductor was prepared in the same manner as in Example 2 except that the surface layer paint was prepared as follows.

  Antimony-containing tin oxide fine particles (trade name: T-1, manufactured by Mitsubishi Materials Corporation) having an average particle diameter of 0.02 μm and surface-treated with (3,3,3-trifluoropropyl) trimethoxysilane are mixed with 100 parts of ethanol. 15 parts of the epoxy-modified phenol resin used in Example 2 was dissolved in a dispersion obtained by adding 96 parts to a dispersion for 96 hours using a sand mill apparatus to obtain a coating material for the surface layer. Using this coating material, a surface layer having a thickness of 3 μm was provided by dip coating on the charge transport layer and heat treatment at 155 ° C. for 1 hour.

<Example 21>
A photoconductor was prepared in the same manner as in Example 20 except that the thickness of the surface layer was changed to 1 μm.

<Example 22>
A photoconductor was prepared in the same manner as in Example 20 except that the thickness of the surface layer was changed to 6 μm.

<Examples 23 to 32>
In Example 20, the resin used for the surface layer was changed to an epoxy-modified resol-type phenol resin obtained by using the epoxy compounds shown in Table 3, respectively, and the film thickness and epoxy modification rate of the surface layer were also shown in Table 3. An electrophotographic photosensitive member was produced in the same manner except that the above was changed.

<Example 33>
A photoconductor was prepared in the same manner as in Example 20 except that the coating material for the surface layer was prepared as follows.

  That is, the surface was treated with (3,3,3-trifluoropropyl) trimethoxysilane. Antimony-containing tin oxide fine particles having an average particle size of 0.02 μm (trade name: T-1, manufactured by Mitsubishi Materials Corporation) in 100 parts of ethanol and dispersed in a sand mill apparatus for 96 hours in a tetrafluoroethylene resin After 8 parts of particles (PTFE particles, trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) were added and further dispersed for 1 hour, 15 parts of the epoxy-modified phenol resin used in Example 20 was dissolved. Thus, a paint for the surface layer was obtained. Using this coating material, a surface layer having a thickness of 3 μm was provided by dip coating on the charge transport layer and heat treatment at 155 ° C. for 1 hour.

<Examples 34 to 45>
In Example 33, the resin used for the surface layer was changed to an epoxy-modified resol-type phenol resin obtained by using the epoxy compounds shown in Table 3, and the film thickness of the surface layer and the epoxy modification rate were also shown in Table 3. An electrophotographic photosensitive member was produced in the same manner except that the above was changed.

<Comparative Example 7>
A photoconductor was prepared in the same manner as in Example 20 except that the surface layer was provided as follows.

  Surface treatment was performed with (3,3,3-trifluoropropyl) trimethoxysilane. In a dispersion obtained by adding 100 parts of methyl ethyl ketone to 25 parts of antimony-containing tin oxide fine particles (trade name: T-1, manufactured by Mitsubishi Materials Corporation) having an average particle size of 0.02 μm and dispersing for 96 hours in a sand mill apparatus, the following structural formula

In this manner, 7.2 parts of a modified burette solution (solid content: 67% by mass) and 10 parts of a novolac type phenol resin (trade name: CMK-2400, manufactured by Showa Polymer Co., Ltd.) are dissolved to obtain a coating solution. It was prepared, applied onto the charge transport layer by spray coating, dried at room temperature for 5 minutes, and then heated at 155 ° C. for 60 minutes to form a surface layer having a thickness of 3 μm.

<Comparative Example 8>
In Example 20, as a resin for the surface layer, a simple blend of 7 parts of phenol resin (trade name: CMK-2400, manufactured by Showa Polymer Co., Ltd.) not subjected to epoxy modification and 3 parts of the following epoxy compound [Chemical Formula 49] An electrophotographic photosensitive member was produced in the same manner except that the material was changed.

<Comparative Example 9>
In Example 20, an electrophotographic photosensitive member was produced in the same manner except that an alkaline resol type phenol resin (manufactured by Asahi Organic Materials Co., Ltd., HP-8300) was used as the resin for the surface layer .

Surface layer configurations of Examples 20 to 45 and Comparative Examples 7 to 9 These electrophotographic photoreceptors and coatings for the surface layers were evaluated by the same test method as described in Example 1, and the surface layers and photosensitive layers were evaluated. Adhesion, surface layer coating stability, sensitivity as an electrophotographic photosensitive member, residual potential (Vr), image quality after a durability test with a laser beam printer in an environment of temperature 30 ° C./humidity 80%, 10,000 The amount of wear of the surface layer per sheet was compared, and the evaluation results are summarized in Table 4.
The evaluation criteria for adhesion and coating film stability are the same as described above.

From the evaluation results of these results of Example 20-45 and Comparative Examples 7-9, when the resin of the present invention is used as a table surface layer it may not observed significant decrease in sensitivity as an electrophotographic photoreceptor, the electrophotographic process It is possible to remarkably improve the durability strength inside. Furthermore, it is possible to maintain sufficient adhesion with the lower charge transport layer. Also, when using a resin of the present invention to prepare a coating material for the front surface layer, there is plenty also the paint stability, it has been found that not any disturb even in continuous production.

According to the present invention, there is provided an electrophotographic photoreceptor having an uppermost surface layer that is excellent in adhesion and wear resistance, has hardness and toughness, and does not deteriorate charge transportability. It becomes possible to provide a process cartridge and an electrophotographic apparatus constituted by using an electrophotographic photosensitive member having these characteristics, and the industrial utility value is extremely large.

1 is a cross-sectional view illustrating an outline of an electrophotographic photosensitive member of the present invention. It is a schematic block diagram of an example of the electrophotographic apparatus used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Primary charging means 4 Image exposure means 5 Development means 6 Transfer means 7 Transfer material 8 Image fixing means 9 Cleaning means 10 Pre-exposure means 11 Process cartridge 12 Rail

Claims (4)

A method for producing an electrophotographic photosensitive member having a photosensitive layer on a conductive support ,
The phenolic hydroxyl groups of Les Orres type phenol resin, and epoxy-modified phenolic resins obtained by the Rukoto by adding the epoxy group of the epoxy compound having two or more epoxy groups in the molecule, a charge transport material and a conductive An electrophotographic photosensitive material comprising a step of forming a surface layer of the electrophotographic photosensitive member by curing a coating film of a coating material for forming a surface layer containing any one or both of fine particles Body manufacturing method . The method for producing an electrophotographic photosensitive member according to claim 1, wherein the epoxy-modified phenol resin does not contain a hetero atom other than oxygen. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the epoxy compound is any one of the following formulae.













. The method for producing an electrophotographic photosensitive member according to any one of claims 1 to 3, wherein said charge transporting substance is one containing a hydroxyl group.