JP2006030704A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having a surface protective layer which has excellent lubricity, is resistant to scraping and flawing, prevents an image defect due to filming etc., is good in coming off of toner and has high durability, in the electrophotographic photoreceptor having a photosensitive layer and a surface protective layer on a conductive substrate. <P>SOLUTION: The electrophotographic photoreceptor having the photosensitive layer and the surface protective layer on the conductive substrate contains cured matter of cyanate ester as a base resin in the surface protective layer. The cured matter is preferably a high polymer which is expressed by general formula (II) (where, R<SP>1</SP>represents an aromatic organic group; n represents an integer of 2 or 3) and is prepared by curing a cyanate ester compound expressed by general formula (I) (where, R<SP>1</SP>and n represent the same as the above). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer and a surface protective layer on a conductive substrate. The electrophotographic photosensitive member of the present invention is particularly preferably mounted on electrophotographic printers, copiers, facsimiles and the like.

  In recent years, electrophotographic photoreceptors, in particular, organic electrophotographic photoreceptors using an organic photoconductive material as a photosensitive layer are non-polluting, can be produced at low cost, and have a high degree of freedom in selecting organic materials. As a result, it has excellent points such as relatively easy design of the photoreceptor characteristics corresponding to the required characteristics of the market. Therefore, many types of electrophotographic photoreceptors have already been announced and are widely used.

  An organic electrophotographic photoreceptor has a structure in which a photosensitive layer mainly composed of an organic material is coated on a conductive substrate. The photosensitive layer has as its main layer a layer in which an organic photoconductive material having a photoconductive function is dispersed in a resin. The photosensitive layer has a structure in which a layer in which a charge generation material is dispersed in a resin (charge generation layer) and a layer in which a charge transport material is dispersed in a resin (charge transport layer), or a charge generation material and charge transport. A single-layer structure in which materials are dispersed in a single resin layer is known. Both types of photoreceptors have already been put into practical use.

  The electrophotographic photoreceptor not only simply satisfies the required sensitivity, electrical characteristics, optical characteristics, etc., but also greatly deteriorates after repeated use by exerting its functions in the electrophotographic process. Therefore, it is necessary to satisfy the characteristic of forming a good image. For example, in the electrophotographic process, the surface of the photosensitive member, that is, the surface of the photosensitive layer farthest from the support (conductive substrate) is subjected to electrical charging such as corona charging, toner development, transfer to paper, and cleaning treatment. Since mechanical and mechanical external forces are applied directly and repeatedly, durability against them is required. Specifically, durability against surface abrasion and scratches due to rubbing and surface degradation due to ozone generated during corona charging is required. On the other hand, there is also a problem of toner fixing (filming) to the surface layer of the photoreceptor due to repeated toner development and cleaning. For this, it is required to improve the cleaning properties of the surface layer.

  In order to satisfy various durability required for the surface layer as described above, an attempt is made to provide a new protective layer mainly composed of a resin on the surface of the photosensitive layer. In view of the mechanical strength of the protective layer, a curable resin is generally excellent. However, even such a curable resin is not sufficient in terms of durability, which is now increasingly demanding by itself, and further, a filler that has an effect of reinforcing the mechanical strength of the resin, and an additive for imparting lubricity Etc. may be required.

  The reason for including a lubricant as the additive is simply to improve the durability by increasing the mechanical strength of the resin, and to provide a protective layer added with a curable resin or further filler to make it difficult to scrape the surface of the protective layer. This is because the surface becomes difficult to be refreshed due to scraping, and on the contrary, the toner tends to adhere to and adhere to the surface of the photosensitive layer by repeated use, filming occurs, and the image is defective.

  On the other hand, regarding the addition of a lubricating component to the surface protective layer to improve the lubricity of the surface, and to reduce the adhesion of the toner to the surface to prevent sticking and to suppress toner filming, In the case of liquid lubricants, there is a problem with the durability of the lubrication effect during repeated use, and in the case of solid lubricants, since finely divided lubricants are mixed in the paint film, it is used as a paint film. Therefore, there is a problem in the dispersibility and dispersion stability of the lubricant fine particles in the coating liquid.

In the case where the surface protective layer is composed of only the curable resin as described above, the electric resistance of the curable resin is generally an electric resistance suitable for the surface protective layer of the electrophotographic photosensitive member (10 ⁸ Ω · cm˜ 10 ¹⁵ Ω · cm) (that is, the insulating property is high), there is a problem that the photoelectric characteristics as a photoconductor are sacrificed as it is. When the photoelectric characteristics are sacrificed, for example, movement of charges generated during exposure in the protective layer is hindered, the bright part potential is not sufficiently lowered, and the bright part potential is increased, so that the development potential margin is narrowed. As a result, and the residual potential after neutralization increases, there arises a problem that the image density is lowered particularly when long-term repetitive printing is performed. In order to avoid such a problem, as the curable resin used for the surface protective layer, it is necessary to increase the conductivity (or lower the insulating property) with a highly insulating resin by using an additive.

  As described above, even when a highly protective surface protective layer is used, the electrical resistance is controlled by dispersing the metal oxide as a filler in the protective layer in the form of fine particles so as not to sacrifice the photoelectric characteristics of the photosensitive layer. A protective layer has already been proposed (Patent Document 1-Claims). It is also known to control the electrical resistance of the resin layer by adding a conductivity imparting agent (Patent Document 2-0060 paragraph). However, in the conventional method of dispersing metal oxide fine particles, there are problems in the dispersibility of the metal oxide fine particles in the binder resin, the cohesiveness, or the transparency of the protective layer. When added to and dispersed in the binder resin, phenomena such as non-uniform conductivity of the protective layer, image defects due to coating unevenness, an increase in residual potential due to repeated charging, and a decrease in sensitivity due to light scattering are likely to occur.

The purpose of dispersing the metal oxide fine particles in the surface protective layer of the electrophotographic photoreceptor or adding a conductivity-imparting agent is to repeat the electrophotographic process by controlling the electrical resistance of the surface protective layer itself. This is to prevent an increase in residual potential in the photosensitive layer, and the appropriate electrical resistance value of the protective layer of such an electrophotographic photosensitive member is about 10 ⁸ Ω · cm to 10 ¹⁵ Ω · cm as described above. It is said that there is.
Japanese Patent Publication No. 6-16213 JP 2003-202893 A

However, in general, the electrical resistance value of the resin, which is the main component for forming the protective layer, is easily influenced by ion conduction due to the hygroscopicity of the resin as the humidity environment of the installation location of the electrophotographic apparatus changes. Therefore, it also has an aspect that it is difficult to maintain good image quality while maintaining the optimum electric resistance value range necessary for the surface protective layer.

Furthermore, in order to increase the lubricity of the protective layer, which is generally the outermost layer, and to disperse particles that control electrical resistance, in order to prevent scattering of incident light by the dispersed particles, the particle size of the particles is larger than the wavelength of the incident light. Must be small, that is, 0.3 μm or less (Patent Document 1). However, in general, metal oxide particles having a particle size of 0.3 μm or less have a particularly strong tendency to agglomerate in a resin solution (coating solution), and it is difficult to uniformly disperse them. Since sedimentation occurs, it is very difficult to produce a dispersion film in which fine particles having a particle size of 0.3 μm or less are stably dispersed. In order to further improve transparency and conductivity uniformity, it is useful to disperse ultrafine particle powder (primary particle size of 0.1 μm or less) with a finer particle size. And dispersion stability tend to be poor (Patent Document 1). More particularly in high humidity, causing a decrease in the surface resistance of the photosensitive member by ozone generated by repeatedly charging process, such as corona products such as NO _X is attached to the protective layer surface, problems such as image flow occurs As a result, there has not yet been obtained a film that exhibits sufficiently satisfactory electrophotographic characteristics as a protective layer.

  The present invention has been made in view of the above-described points, and an object of the present invention is to improve the above-mentioned problems in an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer on a conductive substrate, and to lubricate. It is an object of the present invention to provide an electrophotographic photosensitive member having a highly durable surface protective layer which is excellent in properties, hard to be scraped, hardly scratched, prevents image defects due to filming and the like, and has good toner separation.

  According to the first aspect of the present invention, in the electrophotographic photosensitive member having a photosensitive layer and a surface protective layer on a conductive substrate, the cyanate ester is cured as a base resin in the surface protective layer. This is achieved by containing the product.

（式中、Ｒ¹は芳香族有機基を表し、ｎは２または３の整数を表す）で示されるシアン酸エステル化合物を硬化させた、次式(II)、

（式中、Ｒ¹およびｎは前記のものと同じものを表す）で示される高分子である請求項１記載の電子写真感光体とすることが好ましい。 According to the present invention as set forth in claim 2, the cured product has the following formula (I):

(Wherein R ¹ represents an aromatic organic group and n represents an integer of 2 or 3), a cured cyanate compound represented by the following formula (II):

2. The electrophotographic photosensitive member according to claim 1, wherein R ¹ and n are polymers represented by the same formulas above.

（式中、Ｒ²はＣＨ₂、Ｃ（ＣＨ₃）₂、ＣＨ（ＣＨ₃）、Ｃ（ＣＦ₃）₂、Ｏ、ＳＯ₂、Ｓを表す）で示される請求項１または２記載の電子写真感光体とすることが望ましい。 According to the present invention as set forth in claim 3, the cyanate ester is represented by the following formula (III):

_3. The electron according to claim 1, wherein R ² represents CH ₂ , C (CH ₃ ) ₂ , CH (CH ₃ ), C (CF ₃ ) ₂ , O, SO ₂ , S. A photographic photoreceptor is desirable.

  According to the present invention of claim 4, the surface protective layer contains at least one of a group consisting of a filler mainly composed of a metal oxide, a conductivity imparting agent, and a lubricant. The electrophotographic photosensitive member according to any one of claims 1 to 3 is more preferable.

  According to the present invention, in an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer on a conductive substrate, it has excellent lubricity, is difficult to scrape, is not easily scratched, prevents image defects due to filming, etc. It is possible to provide an electrophotographic photosensitive member having a good and highly durable surface protective layer.

  Hereinafter, embodiments of the electrophotographic photosensitive member of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the examples described below as long as the gist thereof is not exceeded. FIG. 1 is a schematic cross-sectional view of an essential part showing an embodiment of the photoreceptor of the present invention, wherein 1 is a conductive substrate, 2 is an undercoat layer, 3 is a charge generation layer, 4 is a charge transport layer, and 5 is a surface. A protective layer 6 represents a single photosensitive layer. The photosensitive layer is a functionally separated type in which the charge generation layer 3 and the charge transport layer 4 are separated, and a single layer type containing the charge generation material and the charge transport material in the same layer. FIG. 1 (c). FIG. 1A shows a negative charge type in which a charge generation layer 3 and a charge transport layer 4 are laminated in this order on a substrate, and FIG. 1B shows a charge transport layer on the substrate opposite to FIG. 1A. 4 and the charge generation layer 3 are laminated in the order of the positive charge type, and FIG. 1C is a single layer type and mainly a positive charge type.

  The conductive substrate 1 serves as a support for each of the other layers as well as serving as an electrode of the photoreceptor, and may be any of a cylindrical shape, a plate shape, and a film shape, and is made of aluminum, carbon steel, or stainless steel. In addition, a metal such as nickel, or a material obtained by conducting a conductive treatment on glass, resin, or the like may be used.

The undercoat layer 2 is composed of a resin-based layer, an anodized oxide film, or the like, which prevents injection of unnecessary charges from the conductive substrate to the photosensitive layer, covers defects on the substrate surface, and adheres to the photosensitive layer. It is provided as necessary for the purpose of improvement. As the resin binder, polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, silicone resin, polybutyral resin, polyamide resin, and copolymers thereof are appropriately used. It can be used in combination. Further, metal oxide fine particles and the like may be contained in the resin binder. As the metal oxide fine particles, fine particles such as SiO ₂ , TiO ₂ , In ₂ O ₃ and ZrO ₂ can be used.

  The film thickness of the undercoat layer 2 depends on the composition of the undercoat layer 2 but can be arbitrarily set within a range that does not cause an adverse effect such as an increase in residual potential when repeatedly used. The charge generation layer 3 is formed by vacuum-depositing an organic photoconductive substance, or is formed by applying a material in which particles of an organic photoconductive substance are dispersed in a resin binder. appear. In addition, since the charge generation efficiency is high, the injection property of the generated charge into the charge transport layer 4 is important, and the injection property is less dependent on the electric field, and it is desirable that the injection is good even at a low electric field.

  The film thickness of the charge generation layer 3 changes in relation to the magnitude of the light absorption coefficient of the contained charge generation material, and is determined to be a thickness that provides the necessary charge generation capability, and is generally 5 μm or less, Preferably, it is 1 μm or less. The charge generation layer 3 can also be used with a charge generation material as a main component and a charge transport material added thereto. As the charge generation substance, phthalocyanine pigments, azo pigments, anthanthrone pigments, perylene pigments, perinone pigments, squarylium pigments, thiapyrylium pigments, quinacridone pigments, and the like may be used, or these pigments may be used in combination. In particular, as the phthalocyanine pigment, metal-free phthalocyanine, copper phthalocyanine, and titanyl phthalocyanine are preferable. Furthermore, X-type metal-free phthalocyanine, τ-type metal-free phthalocyanine, ε-type copper phthalocyanine, β-type titanyl phthalocyanine, Y-type titanyl phthalocyanine, Preferred is titanyl phthalocyanine having a maximum peak of Bragg angle 2θ of 9.6 ° in the CuKα: X-ray diffraction spectrum described in Kaikai 2004-2874.

  The resin binder used for the charge generation layer 3 includes polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, epoxy resin, polybutyral resin, vinyl chloride copolymer, phenoxy resin, silicone resin, methacrylic ester resin, and these Copolymers and the like can be used in appropriate combinations.

  The charge transport layer 4 is a coating film made of a material in which a charge transport material is dispersed in a resin binder. The charge transport layer 4 retains the charge of the photoreceptor as an insulator layer in the dark, and is injected from the charge generation layer at the time of light reception. Exhibits the function of transporting charges.

  As a charge transport material, a hydrazone compound, a pyrazoline compound, a pyrazolone compound, an oxadiazole compound, an oxazole compound, an arylamine compound, a benzidine compound, a stilbene compound, a charge transporting polymer such as a styryl compound or polyvinylcarbazole, or the like can be used. Is possible.

  As the resin binder used for the charge transport layer 4, a polycarbonate resin, a polyester resin, a polystyrene resin, a methacrylic ester polymer, a copolymer, and the like can be used in appropriate combination.

  The thickness of the charge transport layer 4 is preferably in the range of 3 to 50 μm, more preferably 10 to 40 μm in order to maintain a practically effective surface potential.

  In the case of the single-layer photosensitive layer 6, it is a coating film made of a material in which a charge generation substance and a charge transport substance are dispersed in a resin binder, and the materials used for the charge generation layer 3 and the charge transport layer 4 are similarly used. It is possible. The film thickness is preferably in the range of 3 to 50 μm, more preferably 10 to 40 μm, in order to maintain a practically effective surface potential.

  These photosensitive layers can contain an electron accepting material as necessary for the purpose of improving sensitivity, reducing residual potential, or reducing characteristic fluctuations during repeated use. Examples of the electron acceptor include succinic anhydride, maleic anhydride, dibromosuccinic anhydride, phthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyromellitic anhydride, pyromellitic acid, trimellitic acid, Mention may be made of compounds having a large electron affinity such as trimellitic anhydride, phthalimide, 4-nitrophthalimide, tetracyanoethylene, tetracyanosinodimethane, chloranil, bromanyl, o-nitrobenzoic acid.

  Further, the photosensitive layer may contain a deterioration preventing agent such as an antioxidant or a light stabilizer for the purpose of improving environmental resistance and stability against harmful light. Compounds used for such purposes include chromanol derivatives such as tocopherol and esterified compounds, polyarylalkane compounds, hydroquinone derivatives, etherified compounds, dietherified compounds, benzophenone derivatives, benzotriazole derivatives, thioether compounds, phenylenediamine derivatives. Phosphonic acid ester, phosphorous acid ester, phenol compound, hindered phenol compound, linear amine compound, cyclic amine compound, hindered amine compound and the like.

  The surface protective layer 5 is provided on the outermost surface of the photosensitive layer as shown in FIGS. 1 (a), (b) and (c). The surface protective layer 5 is excellent in lubricity, excellent in durability against mechanical stress, and is composed of a chemically stable material, and has a function of receiving and holding the charge of corona discharge in the dark. In addition, the charge generation layer 3 has the ability to transmit the sensitive light as much as possible, transmits the light at the time of exposure, reaches the charge generation layer 3, receives the generated charge, and neutralizes and eliminates the surface charge. It is necessary to have a function. Further, as described above, it is desirable that the material used be as transparent as possible in the wavelength region of the light absorption maximum of the charge generation material. Moreover, it is preferable that the solvent used when forming the coating film of the surface protective layer does not dissolve the photosensitive layer surface including the lower charge transport layer as much as possible.

Further, as the material of the surface protective layer 5, a material containing a cured product of cyanate ester (cyanate resin) as the base resin of the present invention is suitable. The cured product of cyanate ester as the base resin is preferably used alone, but the effect of the present invention can be obtained by mixing a cured product of cyanate ester as a main component with epoxy resin, acrylic resin, urethane resin, etc. It is done. Further, in the surface protective film mainly composed of a cured product of cyanate ester according to the present invention, it is relatively preferable that the lower resin binder is a polycarbonate resin. This is because the polycarbonate resin has low solubility in methyl ethyl ketone as a solvent used when forming the protective film. Specific compounds of cyanate ester are shown below.

  Catalysts include organometallic compounds such as zinc octylate, tin octylate, acetylacetone zinc, acetylacetone iron and dibutyltin dimaleate, metal salts such as aluminum chloride, tin chloride and zinc chloride, triethylenediamine and dimethylbenzylamine. It is effective to add amines as necessary.

  Further, when a lubricant, a reinforcing filler, a conductive filler (conductivity imparting agent) or the like is added in addition to a cured product of cyanate ester, the function as a surface protective layer is enhanced. Although the detailed reason is unknown, in the case of cyanate resin, even if the above-mentioned lubricant, reinforcing filler, conductive filler, etc. are added, the fluctuation of the electrical resistance of the surface protective layer due to the fluctuation of the environment is relatively small, leading to image quality. The effect of this is small.

  As the lubricant, various silicone oils, fluorine polymer oils and the like are used. As the reinforcing filler, a high molecular weight polymer fine particle or highly crosslinkable polymer fine particle having a diameter of 0.3 μm, more preferably 0.1 μm or less, a fiber diameter of 0.1 μm to 5 μm, and a fiber length of 5 μm to 100 μm, More preferably, the fiber diameter is 0.1 μm to 2 μm, and the fiber length is 5 μm to 40 μm. Organic polymer fibers such as nylon fibers, para-aramid fibers, polyphenylene sulfide fibers, vinylon fibers, or carbon fibers, alumina, boric acid, etc. Inorganic whiskers and metal oxide fine particles such as titanium oxide are used. The inorganic fibers, metal oxide fine particles and the like are preferably subjected to a surface treatment with aminosilane, epoxysilane, methacryloxysilane or the like in order to improve dispersibility in the resin solution (coating solution). Especially as a filler, what has a metal oxide as a main component can be used suitably.

  The film thickness of the surface protective layer 5 can be arbitrarily set within a range that does not cause an adverse effect such as an increase in residual potential when repeatedly used. In addition, even if additives such as the lubricant, reinforcing filler, and conductive filler are not added, if the residual potential is not increased, such as by reducing the thickness of the resin film, only the cured product of cyanate ester However, it can be applied as a surface protective film.

  Next, the fact that the electrophotographic photosensitive member of the present invention has the excellent effects of the present invention as described above will be described through an example of the electrophotographic photosensitive member of the present invention. Hereinafter, “part” represents “part by weight”. Further, in the following examples and comparative examples, the printing durability was evaluated by simulating an actual machine and using a device provided with a urethane cleaning blade, toner, and a toner charging roller around the photosensitive drum. It was rotated (100,000 rotations) and evaluated by the amount of film scraping on the surface of the photosensitive drum by the blade, and used as an index of printing durability. Furthermore, the presence or absence of visual filming after 100,000 revolutions and the magnitude of the frictional resistance against the urethane blade after 100,000 revolutions are based on the magnitude (1.0) of the frictional resistance of any conventional surface protective layer. It was determined as a relative comparison value. The frictional resistance was measured with a surface property measuring machine (HEIDON-14DR, manufactured by Shinto Kagaku Co., Ltd.). If the frictional resistance of the conventional sample and that of the measurement sample are approximately the same, the value is 1.0.

Example 1
A cylindrical photoreceptor (30 mmΦ) was prepared for evaluation of electrical characteristics. An undercoat layer dispersion of the following composition was dip-coated on the aluminum tube, and dried at 100 ° C. for 30 minutes to form an undercoat layer having a thickness of 3 μm.
Alcohol-soluble nylon (CM8000: Toray Industries, Inc.) 5 parts Titanium oxide fine particles treated with aminosilane 5 parts Methanol / methylene chloride mixed solvent (6/4 (v / v)) 90 parts

Next, a charge generation layer dispersion having the following composition was applied by dip coating and dried at 100 ° C. for 30 minutes to form a charge generation layer having a thickness of 0.3 · m.
Titanylphthalocyanine 11 parts Vinyl chloride copolymer resin (MR-110: Nippon Zeon Co., Ltd.) 1 part Methylene chloride 98 parts

９部
下記式で示されるブタジエン化合物（Ｔ４０５：高砂香料工業（株））

１部
ビスフェノールＺ型ポリカーボネート樹脂（商品名：パンライトＴＳ２０５０、帝人化成（株）製） １０部
塩化メチレン ９０部 Next, a charge transport layer solution having the following composition was dip coated and dried at 100 ° C. for 30 minutes to form a charge transport layer having a thickness of 20 μm.
Hydrazone compound represented by the following formula (CTC191: Takasago International Corporation)

9 parts Butadiene compound represented by the following formula (T405: Takasago International Corporation)

1 part bisphenol Z-type polycarbonate resin (trade name: Panlite TS2050, manufactured by Teijin Chemicals Ltd.) 10 parts methylene chloride 90 parts

Next, a surface protective layer solution having the following composition was applied by dip coating and dried at 130 ° C. for 1 hour to form a surface protective layer having a thickness of 3 μm.
Base resin: Bisphenol E-type cyanate ester (trade name Arocy L-10: Bantico Co., Ltd.)-(The above chemical formula (1)) 70 parts Catalyst: 0.4 parts of zinc acetylacetonate Conductivity modifier (conductive filler ): Tin oxide (particle size: 0.02 μm) (NanoTek Powder SnO ₂ : CI Chemical Co., Ltd.) 30 parts Solvent: Methyl ethyl ketone 200 parts or more An electrophotographic photosensitive member was produced.

(Example 2)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below. A surface protective layer solution having the following composition was applied by dip coating and dried at 130 ° C. for 1 hour to form a surface protective layer having a thickness of 3 μm.
Base resin: Bisphenol E type cyanate ester (trade name Arocy L-10: Bantico Co., Ltd.)-(the above chemical formula (1)) 55 parts Catalyst: Zinc acetylacetonate 0.3 part Reinforcing material (reinforcing filler): Inorganic whisker (FTL-300: Ishihara Techno, fiber diameter 0.3 μm, fiber length 5.2 μm) 10 parts Conductivity adjuster: Tin oxide (particle diameter 0.02 μm) (NanoTek Powder SnO ₂ : Cii Kasei) 30 parts solvent : 180 parts of methyl ethyl ketone

Example 3
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below. A surface protective layer solution having the following composition was applied by dip coating and dried at 130 ° C. for 1 hour to form a surface protective layer having a thickness of 3 μm.
Base resin: Bisphenol E-type cyanate ester (trade name Arocy L-10: Bantico Co., Ltd.)-(The above chemical formula (1)) 55 parts Catalyst: Zinc acetylacetonate 0.3 part Lubricating: Silicone modifier ( TSR160) 5 parts Reinforcing material: Titanium oxide fine particles (ET-600W: Ishihara Techno, particle size 0.3 μm)
10 parts Conductivity adjuster: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : CI Kasei) 30 parts Solvent: Methyl ethyl ketone 180 parts

(Comparative Example 1)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: Epoxy resin (THB9502: Kyocera Chemical) 70 parts Conductivity adjuster: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : CI Kasei) 30 parts Solvent: Xylene 100 parts

(Comparative Example 2)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: Urethane resin (isocyanate + polyol) 70 parts Conductivity regulator: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : CI Kasei) 30 parts Solvent: Toluene 100 parts

(Comparative Example 3)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: Acrylic resin (Alloset AST 5221: Nippon Shokubai) 70 parts Conductivity regulator: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : Cii Kasei) 30 parts Solvent: Toluene 100 parts

(Comparative Example 4)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: Phenol resin (PR-912: Sumitomo Bakelite) 70 parts Conductivity regulator: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : CI Kasei) 30 parts Solvent: Isopropyl alcohol 100 parts

(Comparative Example 5)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: Epoxy resin (THB9502) 60 parts Reinforcing material: Inorganic whisker (FTL-300) 10 parts Conductivity regulator: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : Cai Kasei) 30 parts Solvent: 100 parts of xylene

(Comparative Example 6)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: urethane resin (isocyanate + polyol) 60 parts Reinforcing material: Inorganic whisker (FTL-300) 10 parts Conductivity regulator: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : C-I Kasei) 30 parts Solvent: 100 parts of toluene

(Comparative Example 7)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: Acrylic resin (Alloset AST 5221) 60 parts Reinforcing material: Inorganic whisker (FTL-300) 10 parts Conductivity regulator: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : C-I Kasei) 30 parts Solvent : Toluene 100 parts

(Comparative Example 8)
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except for the surface protective layer described below.
Base resin: Phenol resin (PR-912) 60 parts Reinforcing material: Inorganic whisker (FTL-300) 10 parts Conductivity regulator: Tin oxide (particle size 0.02 μm) (NanoTek Powder SnO ₂ : C-I Kasei) 30 parts Solvent: 100 parts isopropyl alcohol

(Comparative Example 9)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface protective layer was not provided.
(Evaluation results)
As an index of printing durability of the surface protective layer, the film scraping amount after 100,000 rotations of the electrophotographic photosensitive member, the presence or absence of filming visually after 100,000 rotations, and the friction resistance between the urethane blades after 100,000 rotations as well Table 1 shows the results of measurement and relative comparison with reference values.

  From Table 1, the film removal amounts of the surface protective layers of Examples 1, 2, and 3 according to the electrophotographic photosensitive member of the present invention are as small as 0.9 μm, 0.4 μm, and 0.1 μm in order, and the filming property is From the results shown in Table 1 regarding the friction resistance of the urethane blade, the cured product of the cyanate ester according to the present invention is related to the compatibility with the urethane blade. It can be seen that the protective film resin is equivalent to or small and good as an epoxy resin, urethane resin, acrylic resin, phenol resin, or the like.

  On the other hand, for the electrophotographic photoreceptors according to Comparative Examples 1 to 9 which do not include the surface protective layer or the surface protective layer not included in the present invention, Comparative Example 1 is a film of 2 μm out of the film thickness of 3 μm of the surface protective layer. That is, there is a problem that the amount of film scraping is too large, Comparative Examples 2 to 8 have a problem in filming property, and Comparative Example 9 is a case where there is no surface protective film. It can be seen that there is a problem in that the frictional resistance against the urethane blade is also increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of an essential part showing an embodiment of the electrophotographic photosensitive member of the present invention, where (a) is a schematic cross-sectional view of the essential part of a laminated electrophotographic photosensitive member, FIG. 2C is a schematic cross-sectional view of a main part of a multilayer electrophotographic photosensitive member, and FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive substrate 2 Undercoat layer 3 Charge generation layer 4 Charge transport layer 5 Protective layer 6 Single layer photosensitive layer

Claims (4)

An electrophotographic photosensitive member having a photosensitive layer and a surface protective layer on a conductive substrate, wherein the surface protective layer contains a cured product of a cyanate ester as a base resin. The cured product has the following formula (I):

(Wherein R ¹ represents an aromatic organic group and n represents an integer of 2 or 3), a cured cyanate compound represented by the following formula (II):

The electrophotographic photosensitive member according to claim 1, wherein R ¹ and n are the same as those described above. The cyanate ester is represented by the following formula (III):

_3. The electron according to claim 1, wherein R ² represents CH ₂ , C (CH ₃ ) ₂ , CH (CH ₃ ), C (CF ₃ ) ₂ , O, SO ₂ , S. Photoconductor. The electrophotography according to any one of claims 1 to 3, wherein the surface protective layer contains at least one of a group consisting of a filler mainly composed of a metal oxide, a conductivity imparting agent, and a lubricant. Photoconductor.

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