JP2014178425A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly durable electrophotographic photoreceptor that has excellent cleanability, electrical characteristics, and wear resistance.SOLUTION: An electrophotographic photoreceptor includes a conductive support, and at least a photosensitive layer and a surface protective layer in this order on the conductive support. The surface protective layer contains a binder resin, and metal oxide fine particles; and the surface protective layer includes the metal oxide fine particles present in the vicinity of the surface; and the metal oxide fine particles have an average primary particle diameter larger than an average primary particle diameter of the metal oxide fine particles present in the vicinity of a boundary with the photosensitive layer. The surface protective layer has the surface of a concave-convex structure; and the concave-convex structure has an average height of concave-convex parts of 0.5 μm or more and 2 μm or less.

Description

  The present invention relates to an electrophotographic photosensitive member, and an image forming apparatus and a process cartridge using the electrophotographic photosensitive member.

  Conventionally, in an electrophotographic process, transfer residual toner adhering to a surface after transferring a toner image to a transfer paper or an intermediate transfer member is removed by a cleaning device as a cleaning unit. .

  As a cleaning member of this cleaning device, one that uses a strip-shaped cleaning blade is well known because it can generally be simplified in configuration and has excellent cleaning performance. This cleaning blade is made of an elastic body such as polyurethane rubber. Then, the base end of the cleaning blade is supported by a support member, the electrophotographic photosensitive member contact portion is pressed against the peripheral surface of the electrophotographic photosensitive member, and the toner remaining on the electrophotographic photosensitive member is damped and scraped off and removed.

Further, in order to meet the recent demand for higher image quality, an image forming apparatus using a toner having a small particle diameter and a nearly spherical shape (hereinafter, polymerized toner) formed by a polymerization method or the like is known. This polymerized toner has characteristics such as higher transfer efficiency than conventional pulverized toner, and can meet the above requirements. However, it is difficult to remove the polymer toner sufficiently from the surface of the electrophotographic photosensitive member using a cleaning blade, and there is a problem that cleaning failure occurs. This is because the polymer toner having a small particle diameter and excellent sphericity passes through a slight gap formed between the blade and the electrophotographic photosensitive member.
In order to suppress such slip-through, it is necessary to increase the contact pressure between the electrophotographic photosensitive member and the cleaning blade to enhance the cleaning ability.

  However, when the contact pressure of the cleaning blade is increased, the cleaning blade is turned over or easily worn, and as a result, the toner cannot be properly cleaned over a long period of time, resulting in poor cleaning.

  As a method for solving these problems, it is conceivable to reduce the contact area with the cleaning blade and reduce the frictional force by roughening the surface of the electrophotographic photosensitive member.

  As one of them, a method has been proposed in which a dimple-shaped concave portion is provided on the surface of the electrophotographic photosensitive member to reduce the friction coefficient of the cleaning blade contact portion, thereby realizing a highly durable image forming apparatus (for example, (See the description of Patent Document 1).

  In addition, a method for realizing a highly durable image forming apparatus by forming a surface shape having a fine uneven structure in a large unevenness on a surface layer of an electrophotographic photosensitive member has been proposed (for example, Patent Documents). 2).

  Further, a highly durable image forming apparatus is formed by forming a surface shape in which grooves are formed linearly in the main scanning direction, which is the circumferential direction, and convex portions are formed by fillers in the “linear grooves”. Has been proposed (for example, see the description of Patent Document 3).

  However, although the durability of the photoconductor and the cleaning blade is improved by these technologies, side effects are caused in the electrical characteristics due to the characteristic surface shape of the photoconductor, and the stability of the image quality is deteriorated. There is a problem that is enough. In addition, since the photoconductor and the cleaning blade come into contact with each other with friction over a long period of time, it is difficult not to change the surface shape of the photoconductor at all. The current situation is not enough.

  An object of the present invention is to solve various problems in the prior art and achieve the following objects. That is, an object of the present invention is to provide a highly durable electrophotographic photoreceptor excellent in cleaning properties, electrical properties, and abrasion resistance.

Means for solving the above-described problems are as follows. That is,
An electrophotographic photoreceptor having a conductive support and at least a photosensitive layer and a surface protective layer in this order on the conductive support, wherein the surface protective layer contains a binder resin and metal oxide fine particles. ,
In the surface protective layer, the average primary particle diameter of the metal oxide fine particles present in the vicinity of the surface is larger than the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer,
The surface of the surface protective layer has an uneven structure,
The electrophotographic photosensitive member is characterized in that an average concavo-convex height of the concavo-convex structure is 0.5 μm or more and 2 μm or less.

  According to the present invention, it is possible to provide a highly durable electrophotographic photosensitive member that can solve the above-described problems and has excellent cleaning properties, electrical characteristics, and abrasion resistance.

FIG. 1 is a schematic diagram relating to the irregularity period and irregularity height of the surface protective layer of the electrophotographic photosensitive member of the present invention. FIG. 2 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 3 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 4 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 5 is a schematic view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 6 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 7 is a schematic view showing an example of the process cartridge of the present invention.

(Electrophotographic photoreceptor)
The electrophotographic photoreceptor of the present invention (hereinafter sometimes simply referred to as “photoreceptor”) has a conductive support and at least a photosensitive layer and a surface protective layer in this order on the conductive support. In addition, it has other layers as required.
The surface protective layer is a surface protective layer defined in the present invention. As the conductive support, the photosensitive layer, and the other layers, the same ones as in the past can be applied.

<Surface protective layer>
The surface protective layer contains a binder resin and metal oxide fine particles, and further contains other components as necessary. In the surface protective layer, the average primary particle diameter of the metal oxide fine particles existing in the vicinity of the surface is larger than the average primary particle diameter of the metal oxide fine particles existing in the vicinity of the boundary with the photosensitive layer. The surface of the surface protective layer has an uneven structure, and the average maximum uneven height of the uneven structure is 0.5 μm or more and 2 μm or less.

<< Binder resin >>
The binder resin is not particularly limited and may be appropriately selected depending on the purpose. For example, AS resin, ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether resin, allyl resin, Phenol resin, polyacetal resin, polyamide resin, polyamideimide resin, polyacrylate resin, polyallylsulfone resin, polybutylene resin, polybutylene terephthalate resin, polycarbonate resin, polyethersulfone resin, polyether resin, polyethylene terephthalate resin, polyimide resin, acrylic resin , Polymethylpentene resin, polypropylene resin, polyphenylene oxide resin, polysulfone resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, epoxy resin, etc. That.

  From the viewpoint of mechanical strength, the binder resin is preferably a cured resin formed by polymerizing a polymerizable compound. More preferable is a cured resin formed by polymerizing a polymerizable compound having 3 or more polymerizable functional groups, and a cured resin formed by polymerizing an acrylic monomer having 3 or more polymerizable functional groups. Further preferred. By polymerizing the polymerizable compound having three or more polymerizable functional groups, a three-dimensional network structure is developed, and a high hardness and high elasticity surface protective layer having a very high crosslinking density is obtained. High wear resistance and scratch resistance are achieved. These may be used alone or in combination of two or more.

-Cured resin-
There is no restriction | limiting in particular as said cured resin, According to the objective, it can select suitably, For example, an acrylic resin, a phenol resin, a urethane resin, an epoxy resin, a silicone resin, an amino resin etc. are mentioned. A UV curable acrylic resin formed from an acrylic polymerizable compound having a polymerizable functional group number of 3 or more is preferable in that it is particularly excellent in wear resistance.

--Acrylic resin--
The acrylic resin is obtained by mixing and crosslinking an acrylic polymerizable compound and a radical polymerization initiator. The synthesis method is not particularly limited and may be appropriately selected depending on the intended purpose. However, a known acrylic polymerizable compound and a known radical polymerization initiator are mixed, and energy such as heating and light irradiation is applied. Then, a method of synthesizing by crosslinking is preferable.

  There is no restriction | limiting in particular as a polymeric functional group in the said acrylic polymerizable compound, Although it can select suitably according to the objective, An acryloyloxy group, a methacryloyloxy group, etc. are preferable at the point of crosslinking reactivity.

  The number of polymerizable functional groups of the acrylic polymerizable compound is not particularly limited and may be appropriately selected depending on the intended purpose. However, two or more are preferable in terms of surface protective layer strength and film forming property, and three The above is more preferable.

  The compound having two polymerizable functional groups of the acrylic polymerizable compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 1,3-butanediol diacrylate, 1,4- Butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, EO-modified bisphenol A diacrylate, EO Examples thereof include modified bisphenol F diacrylate and neopentyl glycol diacrylate.

  The compound having 3 or more polymerizable functional groups of the acrylic polymerizable compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include trimethylolpropane triacrylate (TMPTA) and trimethylolpropane. Trimethacrylate, trimethylolpropane alkylene-modified triacrylate, trimethylolpropane ethyleneoxy-modified (hereinafter EO-modified) triacrylate, trimethylolpropane propyleneoxy-modified (hereinafter PO-modified) triacrylate, trimethylolpropane caprolactone-modified triacrylate, trimethylolpropane Alkylene-modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate Glycerol epichlorohydrin modified (ECH modified) triacrylate, glycerol EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone modified hexaacrylate , Dipentaerythritol hydroxypentaacrylate, alkylated dipentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, phosphoric acid EO Modified triacrylate, 2,2,5,5-te And La hydroxymethyl cyclopentanone tetraacrylate and the like. These may be used alone or in combination of two or more.

  The radical polymerization initiator used in combination with the acrylic polymerizable compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a peroxide initiator, a thermal polymerization initiator; an acetophenone light Polymerization initiator, ketal photopolymerization initiator, benzoin ether photopolymerization initiator, benzophenone photopolymerization initiator, thioxanthone photopolymerization initiator, titanocene photopolymerization initiator, acridine compound, triazine compound, imidazole And photopolymerization initiators such as compounds. These may be used alone or in combination of two or more. Among these, a photopolymerization initiator is preferable.

  Examples of the acetophenone photopolymerization initiator and the ketal photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone. 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1,2-hydroxy-2- Methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime Etc.

  Examples of the benzoin ether photopolymerization initiator include benzoin ether photopolymerization initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, o- Examples include methyl benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, and 1,4-benzoylbenzene.

  Examples of the thioxanthone photopolymerization initiator include 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, and the like.

  Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compounds, triazine compounds, imidazole compounds, etc. Can be mentioned.

  The photopolymerization initiator may be used alone or in combination with a photopolymerization accelerator. The photopolymerization accelerator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, and benzoic acid. Examples include acid (2-dimethylamino) ethyl, 4,4′-dimethylaminobenzophenone, and the like.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5. -Di (peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, 2,2-bis (4,4-di-t-butyl Peroxycyclohexyl) propane-based initiators, azobisisobutylnitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid, etc. And azo initiators.

  There is no restriction | limiting in particular as content of the said radical polymerization initiator, Although it can select suitably according to the objective, 0.5 mass part-40 mass parts are preferable with respect to 100 mass parts of acrylic polymerizable compounds, 1 mass part-20 mass parts are more preferable.

--Phenolic resin--
There is no restriction | limiting in particular as said phenol resin, According to the objective, it can select suitably, For example, a novolak resin, a resole resin, etc. are mentioned. Among these, a resole resin is preferable in that it is excellent in latent image maintenance and can be crosslinked without using the initiator as compared with a novolak resin in which an initiator such as an acid catalyst is essential.

  The phenolic crosslinkable compound is not particularly limited and may be appropriately selected depending on the intended purpose. By heating and crosslinking a phenol derivative having one or more methylol groups in the unit structure. Those synthesized are preferred.

  There is no restriction | limiting in particular as said phenol resin, A commercial item may be used and what was synthesize | combined suitably may be used. The synthesis method is not particularly limited and may be appropriately selected depending on the intended purpose. However, the synthesis method is performed by heating and crosslinking a phenol derivative having one or more methylol groups in the unit structure. Is preferred.

  The phenol derivative having one or more methylol groups in the unit structure is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include dimethylol compounds of phenolic monomers, trimethylol of phenolic monomers. Examples thereof include high molecular weight compounds such as compounds and phenolic dimers. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as a dimethylol compound of the said phenols monomer, According to the objective, it can select suitably, For example, 2, 6- dihydroxymethyl-4-methylphenol, 2, 4- dihydroxymethyl-6-methyl Phenol, 2,6-dihydroxymethyl-3,4-dimethylphenol, 4,6-dihydroxymethyl-2,3-dimethylphenol, 4-t-butyl-2,6-dihydroxymethylphenol, 4-cyclohexyl-2, 6-dihydroxymethylphenol, 2-cyclohexyl-4,6-dihydroxymethylphenol, 2,6-dihydroxymethyl-4-ethylphenol, 4,6-dihydroxymethyl-2-ethylphenol, 4,6-dihydroxymethyl-2 -Isopropylphenol, 6-cyclohex Etc. Le-2,4-dihydroxy-3-methyl phenol.

  The trimethylol compound of the phenolic monomer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include 2,4,6-trihydroxymethylphenol.

-Urethane resin-
There is no restriction | limiting in particular as said urethane resin, According to the objective, it can select suitably, For example, ester type urethane resin, ether type urethane resin, etc. are mentioned. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as said urethane resin, A commercial item may be used and what was synthesize | combined suitably may be used. The method for synthesizing is not particularly limited and may be appropriately selected depending on the intended purpose. However, a known polyol compound and a known isocyanate compound are mixed and subjected to crosslinking by applying energy such as heating and light irradiation. Thus, a method of synthesizing is preferable.

There is no restriction | limiting in particular as said polyol compound, Although it can select suitably according to the objective, A bifunctional or more functional polyol compound is preferable at the point which is excellent in surface strength and film forming property.
The bifunctional or higher functional polyol compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alkylene glycol, alkylene ether glycol, alicyclic diol, and alkylene oxide adduct of alicyclic diol, Diol compounds such as alkylene oxide adducts of bisphenols; polyhydric aliphatic alcohols (eg glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, sorbitol, etc.), trivalent or higher phenols (eg phenol novolac, cresol) Novolak, etc.) and trivalent or higher polyol compounds such as alkylene oxide adducts of trivalent or higher phenols. These may be used alone or in combination of two or more.

There is no restriction | limiting in particular as said isocyanate compound, Although it can select suitably according to the objective, A bifunctional or more isocyanate compound is preferable at the point which is excellent in surface protective layer intensity | strength and film forming property.
The bifunctional or higher functional isocyanate compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, bis ( Isocyanatomethyl) cyclohexane, trimethylhexamethylene diisocyanate, HDI isocyanurate, HDI biuret, XDI trimethylolpropane adduct, IPDI trimethylolpropane adduct, IPDI isocyanurate, and the like. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as content of the said isocyanate compound, Although it can select suitably according to the objective, 0.5 mass part-40 mass parts are preferable with respect to 100 mass parts of said polyol compounds, 1 mass part -20 mass parts is more preferable, and it is preferable to mix | blend an appropriate quantity based on OH value and NCO value.

--- Epoxy resin--
There is no restriction | limiting in particular as said epoxy resin, According to the objective, it can select suitably, For example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a cresol novolak type epoxy resin, a phenol novolak type epoxy resin etc. are mentioned. It is done. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as said epoxy resin, A commercial item may be used and what was synthesize | combined suitably may be used. The method of synthesizing is not particularly limited and may be appropriately selected depending on the purpose. However, an epoxy ring-containing compound having two or more epoxy rings in one molecule and a curing agent are mixed, heated, A method of synthesizing by applying energy such as light irradiation and crosslinking is preferable.

  The epoxy ring-containing compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyalkylene glycol diglycidyl ether, bisphenol A diglycidyl ether, glycerin triglycidyl ether, diglycerol triglycidyl ether, Examples thereof include diglycidyl hexahydrophthalate, trimethylolpropane diglycidyl ether, allyl glycidyl ether, and phenyl glycidyl ether. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as said hardening | curing agent, According to the objective, it can select suitably, For example, a thermal acid generator, a photo-acid generator, etc. are mentioned, Specifically, an aliphatic amine compound, an alicyclic ring, etc. Group amine compounds, aromatic amine compounds, modified amine compounds, polyamidoamines, imidazoles, polymercaptans, acid anhydrides and the like. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as content of the said hardening | curing agent, Although it can select suitably according to the objective, 0.5 mass part-20 mass parts are preferable with respect to 100 mass parts of said epoxy ring containing compounds, 1 More preferred is 10 parts by mass.

--Silicone resin--
The silicone resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, dimethylpolysiloxane, methylphenylpolysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, vinyl silicone, polyether Modified silicone, polyglycerin modified silicone, amino modified silicone, epoxy modified silicone, mercapto modified silicone, methacryl modified silicone, carboxylic acid modified silicone, fatty acid ester modified silicone, alcohol modified silicone, alkyl modified silicone, fluoroalkyl modified silicone, etc. . These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as said silicone resin, A commercial item may be used and what was synthesize | combined suitably may be used. The synthesis method is not particularly limited and may be appropriately selected depending on the intended purpose. However, a reactive organosilicon compound having one or more hydrolyzable groups on a silicon atom may be used alone or mixed with a condensation catalyst. A method of synthesizing by crosslinking by applying energy such as heating is preferable.

  The reactive organosilicon compound is not particularly limited and may be appropriately selected depending on the purpose. For example, two or more hydrolyzable groups are bonded to a silicon atom in terms of excellent surface protective layer strength. A reactive organosilicon compound having a structure is preferred. The hydrolyzable group is not particularly limited and may be appropriately selected depending on the intended purpose. For example, methoxy group, ethoxy group, methyl ethyl ketoxime group, diethylamino group, acetoxy group, propenoxy group, propoxy group, butoxy group And a methoxyethoxy group.

  The condensation catalyst is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a catalyst that acts catalytically in a condensation reaction, a catalyst that moves a reaction equilibrium of a condensation reaction to a production system, etc. Specifically, alkali metal salts such as organic carboxylic acid, nitrous acid, sulfurous acid, aluminate, carbonic acid and thiocyanic acid; organic amine salts such as tetramethylammonium hydroxide and tetramethylammonium acetate; stanna octo And tin organic acid salts such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin mercaptide, dibutyltin thiocarboxylate, and dibutyltin malate.

  There is no restriction | limiting in particular as content of the said condensation catalyst, Although it can select suitably according to the objective, 0.5 mass part-20 mass parts are preferable with respect to 100 mass parts of said reactive organosilicon compounds. 1 mass part-10 mass parts are more preferable.

--Amino resin--
There is no restriction | limiting in particular as said amino resin, According to the objective, it can select suitably, For example, an aniline resin, a melamine resin, a urea resin etc. are mentioned. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular as said amino resin, A commercial item may be used and what was synthesize | combined suitably may be used. The method for synthesizing is not particularly limited and may be appropriately selected depending on the intended purpose. However, a method in which a compound containing an amino group and formaldehyde are mixed, heated and polycondensed is preferred.

<< Metal oxide fine particles >>
The metal oxide fine particles are not particularly limited and can be appropriately selected depending on the purpose. For example, aluminum oxide, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin are doped. Examples thereof include indium oxide, tin oxide doped with antimony and tantalum, and zirconium oxide doped with antimony. These may be used alone or in combination of two or more.

  As the size of the metal oxide fine particles, the average primary particle diameter of the metal oxide fine particles existing in the vicinity of the surface is larger than the average primary particle diameter of the metal oxide fine particles existing in the vicinity of the boundary with the photosensitive layer. .

  The average primary particle diameter of the metal oxide fine particles present in the vicinity of the surface is not particularly limited and may be appropriately selected depending on the intended purpose. However, the wear resistance of the photoreceptor can be increased. For example, the thickness is preferably 0.1 μm or more and 1.0 μm or less.

  The average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 20 nm or more and 40 nm or less are preferable in that excellent electrical characteristics are exhibited at the interface portion of the surface protective layer.

  The average primary particle diameter of the metal oxide fine particles is calculated by calculating the average value of the major axis and the minor axis of the metal oxide particles observed at 50,000 times or more using a scanning electron microscope (SEM). It can be determined by deriving the average value of 10 particles.

  There is no restriction | limiting in particular as content of the said metal oxide fine particle, Although it can select suitably according to the objective, It is preferable that it is 100 to 300 mass parts with respect to 100 mass parts of binder resin. When the content is less than 100 parts by mass, it is difficult to obtain the concavo-convex structure of the present invention, and the cleaning property and electrical characteristics may be insufficient. On the other hand, when the content is more than 300 parts by mass, similarly, it is difficult to obtain the concavo-convex structure of the present invention, and cleaning properties and electrical characteristics may be insufficient.

  The method for dispersing the metal oxide fine particles in the surface protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a dispersion method generally used for preparing a coating solution for the surface protective layer Examples thereof include a method of preparing a dispersion using a ball mill, a sand mill, a KD mill, a three-roll mill, a pressure homogenizer, and ultrasonic dispersion.

<< Other ingredients >>
The other component is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a dispersant, a surfactant, a charge transporting compound, a plasticizer, a leveling agent, and an antioxidant. .

-Dispersant-
There is no restriction | limiting in particular as said dispersing agent, According to the objective, it can select suitably, For example, a polycarboxylic acid type dispersing agent (For example, DISPERBYK (trademark) -P104, DISPERBYK-220S, Big Chemie Japan Co., Ltd.). ), Polyether phosphate dispersant (for example, HIPLAAD ED151, manufactured by Enomoto Kasei Co., Ltd.), polyether ester dispersant (for example, HIPLAAD ED118, HIPLAAD ED350, manufactured by Enomoto Kasei Co., Ltd.) Examples include coalescence. These may be used alone or in combination of two or more.

  The amount of the dispersant added is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5% by mass or more and 50% by mass or less, and preferably 10% by mass or more with respect to the metal oxide fine particles. 40 mass% or less is more preferable, and 15 mass% or more and 30 mass% or less are still more preferable.

-Surfactant-
In the case where the metal oxide fine particles are favorably dispersed in the surface protective layer, a surfactant may be used. There is no restriction | limiting in particular as said surfactant, According to the objective, it can select suitably.
The content of the surfactant is not particularly limited and may be appropriately selected depending on the purpose such as the particle diameter of the metal oxide fine particles, but is 0.5 mass relative to the total amount of the metal oxide fine particles. % To 30% by mass is preferable, and 1% to 15% by mass is more preferable. When the content is less than 0.5% by mass, the dispersion effect of the metal oxide fine particles may not be obtained. When the content exceeds 30% by mass, problems such as a significant increase in residual potential occur. Sometimes.

-Charge transporting compounds-
The charge transporting compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a known hole transporting material having a hole transporting structure such as triarylamine, hydrazone, pyrazoline, and carbazole. A known electron transport material having an electron transport structure such as an electron-withdrawing aromatic ring (condensed polycyclic quinone, diphenoquinone, cyano group, nitro group, etc.) and the like. These may be used alone or in combination of two or more.
Further, when the cross-linked resin is used as the binder resin, a charge transporting compound having a functional group reactive with the cross-linked resin, for example, a hydroxyl group, an acryloyloxy group, a methacryloyloxy group, or the like is used. Also good.

  The content of the charge transporting compound is not particularly limited and may be appropriately selected according to the purpose. However, it is possible to reduce the influence of deterioration of the electrophotographic photoreceptor characteristics due to deterioration of the charge transporting compound. In this respect, 20 parts by mass or less is preferable with respect to 100 parts by mass of the binder resin.

  There is no restriction | limiting in particular as a method of measuring content in the surface protective layer of the said charge transportable compound, According to the objective, it can select suitably, For example, X-ray photoelectron spectroscopy (XPS), energy dispersion type X Method of measuring by elemental analysis such as X-ray spectroscopy (EDX), wavelength dispersive X-ray analyzer (WDX), method of measuring based on dyeing amount stained with reagent, Fourier transform infrared spectroscopy (FT-IR) The method of measuring by is mentioned. Among these, quantification is simple and highly versatile, and it is possible to perform quantification based on a calibration curve created based on the ratio of peak intensities measured by Fourier transform infrared spectroscopy (FT-IR). preferable.

  As the calibration curve, for example, the surface protective layer is prepared by blending a known amount of the charge transporting compound, and the intensity (peak height or peak area) of the vibration peak characteristic of the charge transporting compound is described above. Measured by FT-IR and created based on the ratio of the obtained vibration peak intensities. In order to improve the accuracy of the calibration curve, a surface protective layer prepared with a blending amount of 2 to 5 levels is prepared, and a calibration curve is created based on the vibration peak intensity obtained by the FT-IR measurement. May be. As the vibration peak intensity, it is preferable to use the vibration peak intensity (peak height or peak area) characteristic of the charge transporting compound, which has poor reactivity and has a known compounding ratio in the film. It is more preferable to use the vibration peak intensity.

-Plasticizer-
The plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include dibutyl phthalate and dioctyl phthalate. These may be used alone or in combination of two or more. There is no restriction | limiting in particular as content of the said plasticizer, Although it can select suitably according to the objective, 0.1 mass part-50 mass parts are preferable with respect to 100 mass parts of said binder resins. 5 mass parts-20 mass parts are more preferable.

-Leveling agent-
The leveling agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil; polymers or oligomers having a perfluoroalkyl group in the side chain. And so on. There is no restriction | limiting in particular as content of the said leveling agent, Although it can select suitably according to the objective, 0.001 mass part-5 mass parts are preferable with respect to 100 mass parts of said binder resins.

-Antioxidant-
The antioxidant is not particularly limited, and examples thereof include phenol compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, organic phosphorus compounds, hindered amines, and the like. There is no restriction | limiting in particular as content of the said antioxidant, Although it can select suitably according to the objective, 0.1 mass part-50 mass parts are preferable with respect to 100 mass parts of said binder resins, 0 More preferred is 5 to 20 parts by mass.

<< Method for forming surface protective layer >>
A method for forming the surface protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the surface protective layer includes the binder resin and the metal oxide fine particles, and, if necessary, the other Examples of the method include forming a surface protective layer coating liquid containing the above component by coating the surface of the photosensitive layer of the electrophotographic photoreceptor with UV irradiation or heat drying and curing.

  The surface protective layer has a configuration in which the average primary particle diameter of the metal oxide fine particles present in the vicinity of the surface is larger than the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer. There is no restriction | limiting in particular as a method to obtain, According to the objective, it can select suitably. For example, a method of forming by laminating a layer containing metal oxide fine particles in order on a photosensitive layer using a plurality of surface protective layer coating solutions in which the average primary particle sizes of the contained metal oxide fine particles are different from each other. Is mentioned. In this method, after the first surface protective layer coating solution is applied to the interface side with the photosensitive layer, the next surface protective layer coating solution is applied before curing. Thereby, since the metal oxide fine particles of the upper layer and the lower layer are mixed at the interface portion between these layers, the barrier due to the difference in resistance between the layers is reduced, and the current easily flows uniformly.

  The coating method of the coating solution is not particularly limited and can be appropriately selected according to the purpose of the coating solution, such as the viscosity of the coating solution and the desired thickness of the surface protective layer. For example, a dip coating method, Examples thereof include spray coating, bead coating, ring coating, roll coater, gravure coating, nozzle coating, and screen printing. Among these, the spray coating method is preferable in that the shape of the unevenness on the surface can be easily controlled.

  Since the coating liquid is a solid or a relatively highly viscous liquid at normal temperature, it is preferably prepared by dissolving in a solvent. The solvent is not particularly limited as long as it can dissolve or disperse the above-described components constituting the surface protective layer, and can be appropriately selected according to the purpose. For example, methanol, ethanol, Alcohol solvents such as propanol and butanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran, dioxane and propyl ether; dichloromethane and dichloroethane And halogen solvents such as trichloroethane and chlorobenzene; aromatic solvents such as benzene, toluene and xylene; cellosolve solvents such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These may be used alone or in combination of two or more.

When a curable resin is selected as the binder for the surface protective layer, energy is applied from the outside after coating to cure. The external energy used at this time includes heat, light, radiation, etc., and is selected depending on the resin used. These external energies may be used alone or in combination of two or more. The heating method is not particularly limited and can be appropriately selected depending on the purpose. For example, air, Examples thereof include a method of heating gas such as nitrogen, steam, various heat media, thermal energy such as infrared rays and electromagnetic waves from the coated surface side or the conductive support side.
There is no restriction | limiting in particular as temperature at the time of the said heating, Although it can select suitably according to the objective, 100 to 170 degreeC is preferable. When the temperature is less than 100 ° C., the reaction is slow and the curing reaction may not be completed completely. Further, the amount of the solvent remaining in the surface protective layer is likely to increase, which may affect the characteristics of the electrophotographic photosensitive member. When the temperature exceeds 170 ° C., the curing reaction proceeds non-uniformly and is large in the surface protective layer. There is a possibility that distortion, a large number of unreacted residues and reaction termination terminals may occur, and a low molecular weight component in the photosensitive layer adjacent to the surface protective layer may easily migrate to the surface protective layer.

When a photocurable resin is used as the binder resin, a lamp capable of irradiating energy rays used for curing is used. The lamp is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a low pressure, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a (pulse) xenon lamp, and an electrodeless discharge lamp. Can be mentioned. There is no restriction | limiting in particular as irradiation light quantity of the energy ray to irradiate, Although it can select suitably according to the objective, 50 mW / cm < ² > or more and 1,000 mW / cm < ² > or less are preferable. When the irradiation light quantity is larger than 1,000 mW / cm ² , the reaction progress is non-uniform, local flaws occur on the surface of the surface protective layer, and many unreacted residues and reaction termination ends are generated. There is a fear. In addition, the internal stress increases due to rapid curing, causing cracks and film peeling. When the irradiation light amount is less than 50 mW / cm ² , it takes time for the curing reaction.

  There is no restriction | limiting in particular as said radiation, According to the objective, it can select suitably, For example, an electron beam is mentioned.

  There is no restriction | limiting in particular as thickness of the said surface protective layer, Although it can select suitably according to the objective, 1.5 micrometers or more and 8 micrometers or less are preferable, and 2 micrometers or more and 6 micrometers or less are more preferable. When the thickness of the surface protective layer is 1.5 μm or more and 8 μm or less, an excellent electrophotographic photosensitive member surface can be obtained, and very high wear resistance can be achieved.

  As a method for forming the surface protective layer, a plurality of surface protective layer coating liquids having different average primary particle diameters of the metal oxide fine particles contained therein are sequentially laminated on the photosensitive layer. When the method is employed, the thickness of the layer provided on the interface side with the photosensitive layer is preferably 0.1 μm to 3 μm, and the thickness of the layer provided on the surface side is preferably about 1 to 5 μm.

<< Presence state of metal oxide fine particles in surface protective layer >>
When the surface protective layer is cross-sectionally observed using an electron microscope, metal oxide fine particles having a relatively large average primary particle diameter are present in the vicinity of the surface, and a relative average average particle diameter is present in the vicinity of the boundary with the photosensitive layer. Large metal oxide fine particles are observed.
The boundary vicinity means a portion having a height within 0.1 μm from the boundary surface with the photosensitive layer.
On the other hand, the surface vicinity portion means a portion having a depth within 1 μm from the surface of the surface protective layer.

<< Uneven structure >>
The concavo-convex structure is not particularly limited as long as the average concavo-convex height is not less than 0.5 μm and not more than 2 μm, and can be appropriately selected according to the purpose, but the average concavo-convex period is not less than 10 mm and not more than 50 mm. Is preferred.

The concavo-convex height and the concavo-convex cycle (interval between adjacent convex portions) in the concavo-convex structure can be measured, for example, by examining a cross-sectional curve using a surface roughness meter (FIG. 1).
Examples of the surface roughness meter include Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.).
Using the surface roughness meter, the height of the concavo-convex structure and the concavo-convex cycle can be measured by driving a measurement pickup under the conditions of a measurement length of 100 mm and a measurement speed of 0.3 mm / s.

  The average unevenness height and the average unevenness period are the average values of the unevenness height and the unevenness period measured at arbitrary 10 locations, respectively.

<Photosensitive layer>
The photosensitive layer may be a laminated type photosensitive layer or a single layer type photosensitive layer.

<< Single-layer type photosensitive layer >>
The single-layer type photosensitive layer is a layer having a charge generation function and a charge transport function at the same time.
The single-layer type photosensitive layer contains a charge generating substance, a charge transporting substance, and a binder resin, and further contains other components as necessary.

-Charge generation material-
The charge generating material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include the same materials as those used in the laminated photosensitive layer described later. There is no restriction | limiting in particular as content of the said charge generation substance, Although it can select suitably according to the objective, 5 mass parts-40 mass parts are preferable with respect to 100 mass parts of said binder resins.

-Charge transport material-
There is no restriction | limiting in particular as said charge transport substance, According to the objective, it can select suitably, For example, the substance similar to what is used by the laminated type photosensitive layer mentioned later etc. are mentioned. There is no restriction | limiting in particular as content of the said charge transport material, Although it can select suitably according to the objective, 190 mass parts or less are preferable with respect to 100 mass parts of said binder resin, and 50 mass parts-150 masses. Part is more preferred.

-Binder resin-
There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably, For example, the binder resin similar to what is used by the laminated type photosensitive layer mentioned later etc. are mentioned.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the purpose. For example, the same low molecular charge transport material, the same solvent, and the same as those used in the laminated photosensitive layer described later A leveling agent, the above-mentioned antioxidant, etc. are mentioned.

-Method for forming a single-layer type photosensitive layer-
The method for forming the single-layer photosensitive layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a charge generating material, a charge transporting material, a binder resin, other components, etc. Examples thereof include a method of forming a coating liquid obtained by dissolving or dispersing in a suitable solvent (for example, tetrahydrofuran, dioxane, dichloroethane, cyclohexane, etc.) by coating or drying.

  There is no restriction | limiting in particular as a method to apply the said coating liquid, According to the objective, it can select suitably, For example, a dip coating method, a spray coat, a bead coat, a ring coat etc. are mentioned. Moreover, you may add a plasticizer, a leveling agent, antioxidant, etc. as needed.

  There is no restriction | limiting in particular as thickness of the said single layer type photosensitive layer, Although it can select suitably according to the objective, 5 micrometers-25 micrometers are preferable.

<< Laminated Photosensitive Layer >>
Since the layered photosensitive layer has independent charge generation functions and charge transport functions, it has at least a charge generation layer and a charge transport layer in this order. In addition, a conventionally well-known thing can be used for the said charge generation layer and the said charge transport layer.

  In the multilayer photosensitive layer, the stacking order of the charge generation layer and the charge transport layer is not particularly limited and may be appropriately selected depending on the purpose. However, many charge generation materials have poor chemical stability, and when exposed to an acidic gas such as a discharge product around a charger in an electrophotographic imaging process, the charge generation efficiency is reduced. For this reason, it is preferable to laminate the charge transport layer on the charge generation layer.

-Charge generation layer-
The charge generation layer includes a charge generation material, preferably includes a binder resin, and further includes other components such as the above-described antioxidant as necessary.

-Charge generation material-
There is no restriction | limiting in particular as said charge generation substance, According to the objective, it can select suitably, For example, an inorganic material, an organic material, etc. are mentioned.

---- Inorganic material ---
The inorganic material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, amorphous silicon (For example, a dangling bond that is terminated with a hydrogen atom, a halogen atom, or the like; a boron atom, a phosphorus atom, or the like is preferred).

---- Organic materials ---
The organic material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine; azulenium salt pigments, squaric acid methine pigments, and carbazole skeletons. Azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, azo pigments having a dibenzothiophene skeleton, azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo having a bisstilbene skeleton Pigment, azo pigment having distyryl oxadiazole skeleton, azo pigment having distyryl carbazole skeleton, perylene pigment, anthraquinone or polycyclic quinone pigment, quinoneimine pigment, diphenylmethane and triphenylmethane face , Benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, indigoid pigments, and bis-benzimidazole-based pigments. These may be used individually by 1 type and may use 2 or more types together.

--Binder resin--
The binder resin is not particularly limited and can be appropriately selected according to the purpose. For example, polyamide resin, polyurethane resin, epoxy resin, polyketone resin, polycarbonate resin, silicone resin, acrylic resin, polyvinyl butyral resin, Examples thereof include polyvinyl formal resin, polyvinyl ketone resin, polystyrene resin, poly-N-vinyl carbazole resin, polyacrylamide resin and the like. These may be used individually by 1 type and may use 2 or more types together.

  As the binder resin, in addition to the above-mentioned binder resin, a charge transporting polymer material having a charge transport function may be included.For example, an arylamine skeleton, a benzidine skeleton, a hydrazone skeleton, a carbazole skeleton, a stilbene skeleton, A polymer material having a pyrazoline skeleton or the like, such as a polycarbonate, polyester, polyurethane, polyether, polysiloxane, or acrylic resin, or a polymer material having a polysilane skeleton can be used.

-Other ingredients-
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a low molecular charge transport material, a solvent, a leveling agent etc. are mentioned, You may contain the above-mentioned antioxidant.
There is no restriction | limiting in particular as content of the said other component, Although it can select suitably according to the objective, 0.01 mass%-10 mass% are preferable with respect to the total mass of the layer to add.

--- Low molecular charge transport material ---
There is no restriction | limiting in particular as said low molecular charge transport material, According to the objective, it can select suitably, For example, an electron transport material, a hole transport material, etc. are mentioned.

  The electron transport material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, chloroanil, bromilyl, 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-trinitrodibenzothiophene-5,5-dioxide, diphenoquinone derivatives and the like. These may be used individually by 1 type and may use 2 or more types together.

  The hole transport material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, and triarylamine derivatives. , Stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc. Derivatives, enamine derivatives and the like. These may be used individually by 1 type and may use 2 or more types together.

--- Solvent ---
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose.For example, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl ketone, Acetone, ethyl acetate, butyl acetate and the like can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

--- Leveling agent ---
There is no restriction | limiting in particular as said leveling agent, According to the objective, it can select suitably, For example, silicone oils, such as dimethyl silicone oil and methylphenyl silicone oil, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

--Method of forming charge generation layer--
The method for forming the charge generation layer is not particularly limited and may be appropriately selected depending on the purpose. For example, the charge generation material and the binder resin are dissolved or dispersed in the other components such as the solvent. For example, a method of forming the coating liquid obtained by applying the coating liquid on the conductive support and drying it may be used. In addition, the said coating liquid can be apply | coated by the casting method etc.

  There is no restriction | limiting in particular as thickness of the said charge generation layer, Although it can select suitably according to the objective, 0.01 micrometer-5 micrometers are preferable, and 0.05 micrometer-2 micrometers are more preferable.

-Charge transport layer-
The charge transport layer is a layer intended to hold a charged charge and to couple the charge generated and separated in the charge generation layer by exposure to the charged charge held by movement. In order to achieve the purpose of holding the charged charge, it is required that the electric resistance is high. Further, in order to achieve the purpose of obtaining a high surface potential with the charged charge that has been held, it is required that the dielectric constant is small and the charge mobility is good.

  The charge transport layer preferably includes a charge transport material, preferably includes a binder resin, and further includes other components as necessary.

-Charge transport material-
The charge transport material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an electron transport material, a hole transport material, and a polymer charge transport material.

  There is no restriction | limiting in particular as content in the charge transport layer whole quantity of the said charge transport material, Although it can select suitably according to the objective, 20 mass%-80 mass% are preferable, and 30 mass%-70 mass% are preferable. More preferred. If the content is less than 20% by mass, the charge transporting property of the charge transport layer may be reduced, so that desired light attenuation characteristics may not be obtained. The body may wear more than necessary due to various hazards. On the other hand, when the content of the charge transport material in the charge transport layer is within the more preferable range, a desired light attenuation can be obtained, and an electrophotographic photoreceptor with less wear can be obtained by use. This is advantageous.

---- Electron transport material ---
The electron transport material (electron-accepting material) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 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] thiophene-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and the like. These may be used alone or in combination of two or more.

--- Hole transport material ---
The hole transport material (electron donating material) is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (P-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, Examples include acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These may be used alone or in combination of two or more.

--- Polymer charge transport material ---
The polymer charge transport material is a material having both the functions of a binder resin and a charge transport material described later.

  The polymer charge transport material is not particularly limited and may be appropriately selected depending on the intended purpose.For example, a polymer having a carbazole ring, a polymer having a hydrazone structure, a polysilylene polymer, or a triarylamine structure may be used. For example, a polymer having a triarylamine structure described in Japanese Patent No. 3852812, Japanese Patent No. 3990499, and the like, a polymer having an electron donating group, and other polymers. These may be used individually by 1 type, may use 2 or more types together, and may use together with the binder resin mentioned later at the point of abrasion durability or film forming property.

  The content of the polymer charge transport material in the total mass of the charge transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. The polymer charge transport material and the binder resin are used in combination. In the case, 40 mass%-90 mass% is preferable, and 50 mass%-80 mass% is more preferable.

--Binder resin--
The binder resin is not particularly limited and can be appropriately selected depending on the purpose. For example, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyethylene resin, polyvinyl chloride resin, polyvinyl acetate resin, Polystyrene resin, phenol resin, epoxy resin, polyurethane resin, polyvinylidene chloride resin, alkyd resin, silicone resin, polyvinyl carbazole resin, polyvinyl butyral resin, polyvinyl formal resin, polyacrylate resin, polyacrylamide resin, phenoxy resin, and the like are used. These may be used alone or in combination of two or more.
The charge transport layer may also contain a copolymer of a crosslinkable binder resin and a crosslinkable charge transport material.

-Other ingredients-
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a solvent, a plasticizer, a leveling agent, etc. are mentioned, You may contain antioxidant mentioned above.
There is no restriction | limiting in particular as content of the said other component, Although it can select suitably according to the objective, 0.01 mass%-10 mass% are preferable with respect to the total mass of the layer to add.

--- Solvent ---
The solvent is not particularly limited and may be appropriately selected depending on the purpose. The same solvent as the charge generation layer can be used, but a solvent that dissolves the charge transport material and the binder resin satisfactorily. preferable. These may be used singly or in combination of two or more.

---- Plasticizer ---
The plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate.

--- Leveling agent ---
The leveling agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil; polymers or oligomers having a perfluoroalkyl group in the side chain. Etc.

--Method of forming charge transport layer--
The method for forming the charge transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the charge transport material and the binder resin are dissolved or dispersed in the other components such as the solvent. And a method of forming the coating liquid obtained by applying the coating liquid on the charge generation layer and heating or drying.

  The method for applying the coating liquid used for forming the charge transport layer is not particularly limited, and may be appropriately selected according to the purpose such as the viscosity of the coating liquid and the desired thickness of the charge transport layer. Examples thereof include a dip coating method, a spray coating method, a bead coating method, and a ring coating method.

From the viewpoint of electrophotographic characteristics and film viscosity, the charge transport layer needs to be heated by some means to remove the solvent from the charge transport layer.
Examples of the heating method include a method of heating heat energy such as air, nitrogen and other gases, steam, various heat media, infrared rays, and electromagnetic waves from the coated surface side or the support side.
There is no restriction | limiting in particular as temperature at the time of the said heating, Although it can select suitably according to the objective, 100 to 170 degreeC is preferable. When the temperature is less than 100 ° C., the organic solvent in the film cannot be sufficiently removed, and electrophotographic characteristics and wear durability may be deteriorated. On the other hand, when the temperature exceeds 170 ° C., not only the surface of the surface is distorted and cracks are generated, peeling occurs at the interface with the adjacent layer, etc., but volatile components in the photosensitive layer are scattered to the outside. In this case, desired electrical characteristics may not be obtained.

  There is no restriction | limiting in particular as thickness of the said charge transport layer, Although it can select suitably according to the objective, From the point of resolution thru | or response, 50 micrometers or less are preferable and 45 micrometers or less are more preferable. The lower limit varies depending on the system to be used (particularly charging potential), but is preferably 5 μm or more.

<Other layers>
There is no restriction | limiting in particular as said other layer, According to the objective, it can select suitably, For example, an undercoat layer, an intermediate | middle layer, etc. are mentioned.

-Undercoat layer-
The undercoat layer can be provided between the conductive support and the photosensitive layer.
The undercoat layer contains a resin and, if necessary, further contains other components such as the above-mentioned antioxidant, fine powder pigment, and coupling agent.

The resin contained in the undercoat layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include water-soluble resins such as polyvinyl alcohol, casein and sodium polyacrylate, copolymer nylon, and methoxymethyl. Examples thereof include alcohol-soluble resins such as nylon fluoride, curable resins that form a three-dimensional network structure, such as polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy resin.
Among these, a resin having a high solvent resistance with respect to a general organic solvent is preferable in that a photosensitive layer is coated on the resin with a solvent.

  The fine powder pigment contained in the undercoat layer is not particularly limited as long as it is a pigment that can prevent moire, reduce residual potential, etc., and can be appropriately selected according to the purpose. Examples thereof include metal oxides such as titanium, silica, alumina, zirconium oxide, tin oxide, and indium oxide.

  There is no restriction | limiting in particular as a coupling agent contained in the said undercoat layer, According to the objective, it can select suitably, For example, a silane coupling agent, a titanium coupling agent, a chromium coupling agent etc. are mentioned.

  There is no restriction | limiting in particular as said undercoat layer, According to the objective, it can select suitably, For example, a single layer may be sufficient and the lamination | stacking of two or more layers may be sufficient.

A method for forming the undercoat layer is not particularly limited, and can be formed by using an appropriate solvent and a coating method as in the above-described photosensitive layer. For example, a method of forming by anodizing Al ₂ O ₃ And an organic material such as polyparaxylylene (parylene); an inorganic material such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, and CeO ₂ ; by a vacuum thin film manufacturing method.

  There is no restriction | limiting in particular as thickness of the said undercoat layer, Although it can select suitably according to the objective, 1 micrometer-5 micrometers are preferable.

-Intermediate layer-
The intermediate layer can be provided between the charge transport layer and the surface protective layer for the purpose of suppressing mixing of charge transport layer components into the surface protective layer or improving adhesion between the two layers. .

  The intermediate layer includes a binder resin, and further includes other components such as the above-described antioxidant as necessary. The intermediate layer coating liquid is preferably one that is insoluble or hardly soluble in the surface protective layer coating liquid.

  There is no restriction | limiting in particular as binder resin contained in the said intermediate | middle layer, According to the objective, it can select suitably, For example, polyamide, alcohol soluble nylon, polyvinyl butyral, polyvinyl alcohol, etc. are mentioned.

  There is no restriction | limiting in particular as a formation method of the said intermediate | middle layer, According to the objective, it can select suitably, For example, the method etc. which form using the suitable solvent and coating method similar to the said photosensitive layer are mentioned.

  There is no restriction | limiting in particular as thickness of the said intermediate | middle layer, Although it can select suitably according to the objective, 0.05 micrometer-2 micrometers are preferable.

<Conductive support>
The conductive support is not particularly limited as long as it has a volume resistivity of 1 × 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose. An endless belt (such as an endless nickel belt or an endless stainless steel belt) disclosed in Japanese Patent Laid-Open No. 52-36016 may be used.

  There is no restriction | limiting in particular as a formation method of the said electroconductive support body, According to the objective, it can select suitably, For example, a metal (aluminum, nickel, chromium, nichrome, copper, gold | metal | money, silver, platinum etc.) or a metal A method of forming an oxide (tin oxide, indium oxide, etc.) by depositing or sputtering and coating a support (film, cylindrical plastic, paper, etc.); metal (aluminum, aluminum alloy, nickel, For example, a method of extruding a plate of stainless steel, etc., performing drawing, etc., and performing surface treatment (cutting, superfinishing, polishing, etc. after forming a blank), and the like.

The conductive support may be provided with a conductive layer on the conductive support.
The method for forming the conductive layer is not particularly limited and may be appropriately selected depending on the purpose. For example, the conductive layer and the binder resin may be dispersed or dissolved in a solvent as necessary. A method of forming the applied coating liquid on the conductive support, such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon (registered trademark) Examples include a method of forming using a heat-shrinkable tube containing conductive powder.

  There is no restriction | limiting in particular as said electroconductive powder, According to the objective, it can select suitably, For example, carbon fine particles, such as carbon black and acetylene black; Aluminum, nickel, iron, nichrome, copper, zinc, silver, etc. And metal oxide powders such as conductive tin oxide and ITO.

  There is no restriction | limiting in particular as binder resin used for the said electroconductive layer, According to the objective, it can select suitably, For example, a thermoplastic resin, a thermosetting resin, a photocurable resin etc. are mentioned, Specifically, Are polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate resin, Polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Melamine resin, Ureta Resins, phenol resins, and alkyd resins.

  There is no restriction | limiting in particular as a solvent used for the said electroconductive layer, According to the objective, it can select suitably, For example, tetrahydrofuran, a dichloromethane, methyl ethyl ketone, toluene etc. are mentioned.

[Embodiment of electrophotographic photosensitive member]
Hereinafter, embodiments of the electrophotographic photosensitive member of the present invention will be described.

<First Embodiment>
The layer structure of the electrophotographic photosensitive member according to the first embodiment will be described with reference to FIG.
FIG. 2 is a diagram showing a layer structure of an electrophotographic photosensitive member having a single-layer type photosensitive layer, in which a single-layer type photosensitive layer 26 and a surface protective layer 25 are sequentially laminated on a conductive support 21. is there.

<Second Embodiment>
The layer structure of the electrophotographic photosensitive member according to the second embodiment will be described with reference to FIG.
FIG. 3 shows a configuration having a laminated photosensitive layer, and shows a layer configuration of an electrophotographic photosensitive member in which a charge generation layer 23, a charge transport layer 24, and a surface protective layer 25 are sequentially laminated on a conductive support 21. It is a figure. The charge generation layer 23 and the charge transport layer 24 correspond to the photosensitive layer.

<Third Embodiment>
The layer structure of the electrophotographic photosensitive member according to the third embodiment will be described with reference to FIG.
4 has a configuration in which an intermediate layer is further provided on the electrophotographic photosensitive member having the configuration of FIG.
FIG. 4 is a diagram showing a layer structure of an electrophotographic photosensitive member in which an undercoat layer 22, a charge generation layer 23, a charge transport layer 24, and a surface protective layer 25 are sequentially laminated on a conductive support 21. The charge generation layer 23 and the charge transport layer 24 correspond to the photosensitive layer.

<Fourth Embodiment>
The layer structure of the electrophotographic photosensitive member according to the fourth embodiment will be described with reference to FIG.
FIG. 5 shows a structure having a laminated photosensitive layer, and shows a layer structure of an electrophotographic photoreceptor in which a charge transport layer 24, a charge generation layer 23, and a surface protective layer 25 are sequentially laminated on a conductive support 21. It is a figure. The charge generation layer 23 and the charge transport layer 24 correspond to the photosensitive layer.

(Image forming device)
The image forming apparatus includes: an electrophotographic photosensitive member; a charging unit that charges a surface of the electrophotographic photosensitive member; an exposure unit that exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image; Developing means for developing a latent image with toner to form a visible image, transfer means for transferring the visible image to a recording medium, and cleaning means for removing toner remaining on the electrophotographic photosensitive member It has at least, and further has other means as needed. The electrophotographic photosensitive member used in the image forming apparatus is the above-described electrophotographic photosensitive member of the present invention. The charging unit and the exposure unit may be collectively referred to as an electrostatic latent image forming unit.

<Charging means>
The charging means is not particularly limited and may be appropriately selected according to the purpose. For example, a known contact charger including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotron and scorotron (including proximity-type non-contact chargers having a gap of 100 μm or less between the surface of the electrophotographic photosensitive member and the charger).

<Exposure means>
The exposure means is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charging means can be exposed like an image to be formed, and can be appropriately selected according to the purpose. Examples include various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system, and examples of the light source in the exposure device include a light emitting diode (LED) and a semiconductor laser. (LD), electroluminescence (EL), etc. and the light source etc. which can ensure high brightness | luminance are mentioned. In the present invention, an optical backside system that performs imagewise exposure from the backside of the electrophotographic photosensitive member may be employed.

<Developing means>
The developing means is not particularly limited and may be appropriately selected depending on the purpose. For example, as long as development can be performed using the toner or developer, there is no particular limitation, and the developing means is appropriately selected according to the purpose. However, it is preferable to have at least a developing unit that accommodates the developer and can apply the developer to the electrostatic latent image in a contact or non-contact manner. The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multicolor developing unit. For example, a developer having a stirrer for charging the developer by frictional stirring and a rotatable magnet roller is preferable. In the developing device, for example, the toner and the external additive are mixed and stirred, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. The Since the magnet roller is disposed in the vicinity of the electrophotographic photosensitive member, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted to the electrophotographic photosensitive member. Move to the surface of the body. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrophotographic photosensitive member.

  There is no restriction | limiting in particular as said external additive, According to the objective which assists fluidity | liquidity, developability, and electrification property, it can select suitably, For example, an inorganic fine particle, polymeric fine particle, etc. are mentioned. Among these, inorganic fine particles are preferable.

The inorganic fine particles are not particularly limited and can be appropriately selected depending on the purpose. For example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, oxide Tin, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, etc. Can be mentioned.
The specific surface area by the BET method, not particularly limited and may be appropriately selected depending on the intended ^purpose, 20m ² / ^g~500m 2 / g are preferred.
The amount of the inorganic fine particles added to the toner particles is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably 0.01% by mass to 5% by mass, and 0.01% by mass to 2% by mass. More preferred.

The polymer fine particles are not particularly limited and can be appropriately selected depending on the purpose. For example, polystyrene, methacrylic acid ester or acrylic acid ester copolymer obtained by soap-free emulsion polymerization, suspension polymerization, or dispersion polymerization can be used. Examples thereof include polymer, polycondensation systems such as silicone, benzoguanamine, and nylon, and polymer particles made of thermosetting resin.

The external additive is surface treated with a surface treatment agent to increase hydrophobicity and prevent deterioration of the external additive itself even under high humidity.
The surface treatment agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, and an organic titanate coupling agent. , Aluminum coupling agents, silicone oils, modified silicone oils, and the like.

<Transfer means>
The transfer means is a means for transferring the visible image to a recording medium, and uses a method for directly transferring a visible image from the surface of the electrophotographic photosensitive member to a recording medium, and an intermediate transfer member. There is a method in which a visible image is primarily transferred onto the recording medium, and then the visible image is secondarily transferred onto the recording medium. Either aspect can be used satisfactorily, but the former (direct transfer) method with a small number of transfers is preferred when the adverse effect of the transfer is great when the image quality is improved. The transfer can be performed, for example, by charging the electrophotographic photosensitive member with the transfer charger using the visible image, and can be performed by the transfer unit.

<Cleaning means>
The cleaning means is not particularly limited as long as it can remove the electrophotographic toner remaining on the electrophotographic photosensitive member, and can be appropriately selected from known cleaners. For example, a magnetic brush cleaner , Electrostatic brush cleaner, magnetic roller cleaner, blade cleaner, brush cleaner, web cleaner and the like.

  Examples of the blade cleaner include a strip-shaped elastic blade that removes toner by bringing the tip ridge portion of the elastic blade into contact with the surface of the electrophotographic photosensitive member. There is no restriction | limiting in particular as a material of the said elastic body blade, Generally a well-known material can be selected suitably according to the objective, For example, rubber | gum etc. are mentioned.

<Other means>
There is no restriction | limiting in particular as said other means, According to the objective, it can select suitably, For example, a fixing means, a static elimination means, a recycling means, a control means, etc. are mentioned.

-Fixing means-
The fixing unit is not particularly limited and may be appropriately selected depending on the purpose. However, a known heating and pressing unit is preferable, and the heating and pressing unit includes a combination of a heating roller and a pressing roller, A combination of a heating roller, a pressure roller, and an endless belt is exemplified, and the heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C. The fixing may be performed, for example, every time the toner of each color is transferred to the recording medium, or may be performed simultaneously in a state where the toner of each color is stacked.

-Static elimination means-
The neutralizing means is not particularly limited and may be appropriately selected from known neutralizers as long as it can apply a neutralizing bias to the electrophotographic photosensitive member. For example, a neutralizing lamp is preferably used. Can be mentioned.

-Recycling means-
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

-Control means-
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

[Embodiment of Image Forming Apparatus]
Hereinafter, embodiments of the image forming apparatus of the present invention will be described.
FIG. 6 is a schematic diagram for explaining the image forming apparatus of the present invention. A charging unit 3, an exposing unit 5, a developing unit 6, a transfer unit 10 and the like are arranged around the electrophotographic photosensitive member 1. FIG.

  First, the electrophotographic photosensitive member 1 is charged on average by the charging means 3 shown in FIG. As the charging means 3, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known system can be used.

  Next, an electrostatic latent image is formed on the uniformly charged electrophotographic photosensitive member 1 by the exposure means 5 shown in FIG. As the light source, all luminescent materials 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) 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.

  Next, the electrostatic latent image formed on the electrophotographic photoreceptor 1 is visualized by the developing means 6 shown in FIG. Examples of the developing method include a one-component developing method using a dry toner, a two-component developing method, and a wet developing method using a wet toner. When the electrophotographic photoreceptor 1 is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photoreceptor. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

  Next, the toner image visualized on the electrophotographic photoreceptor 1 is transferred onto the recording medium 9 by the transfer means 10 shown in FIG. In addition, a pre-transfer charger 7 may be used for better transfer. As the transfer means 10, an electrostatic transfer method using a transfer charger, a bias roller, or the like; a mechanical transfer method such as an adhesive transfer method or a pressure transfer method; a magnetic transfer method, or the like can be used.

  Further, if necessary, a separation charger 11 and a separation claw 12 may be used as means for separating the recording medium 9 shown in FIG. 6 from the electrophotographic photosensitive member 1. As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger 11, the charging means can be used. In addition, cleaning means such as a fur brush 14 and a cleaning blade 15 are used to clean the toner remaining on the photoconductor after transfer, and the pre-cleaning charger 13 may be used for more efficient cleaning. Good. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination. Further, in order to remove the latent image on the electrophotographic photosensitive member 1, the charge eliminating means 2 may be used. As the charge removal means 2, a charge removal lamp, a charge removal charger or the like is used, and the exposure light source and the charging means can be used, respectively. In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.

(Process cartridge)
The process cartridge of the present invention includes an electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, Developing means for developing an electrostatic latent image with toner to form a visible image, transfer means for transferring the visible image to a recording medium, and cleaning for removing toner remaining on the electrophotographic photosensitive member It has at least one of the means, and further has other means as necessary. The electrophotographic photosensitive member used in the process cartridge of the present invention is the above-described electrophotographic photosensitive member of the present invention.

  As shown in FIG. 7, the process cartridge includes an electrophotographic photosensitive member 101, and at least one of a charging unit 102, a developing unit 104, a transfer unit 106, a cleaning unit 107, and a discharging unit (not shown). And an apparatus (part) that can be attached to and detached from the main body of the image forming apparatus. Referring to the image forming process using the process cartridge of FIG. 7, the photosensitive member 101 is charged in the direction of the arrow while being charged by the charging unit 102 and exposed by the exposure unit 103. The electrostatic latent image is developed with toner by the developing unit 104, and the toner development is transferred to the recording medium 105 by the transfer unit 106 and printed out. Next, the surface of the photoconductor after the image transfer is cleaned by the cleaning unit 107 and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example. In addition, all "parts" used in an Example represent a mass part.

(Manufacture of electrophotographic photoreceptors)
<Example 1>
On an aluminum cylinder having a diameter of 40 mm, an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition are sequentially dip coated and dried to obtain an average thickness of 3.5 μm. An undercoat layer, a charge generation layer having an average thickness of 0.2 μm, and a charge transport layer having an average thickness of 23 μm were formed. After coating each layer, it was dried by touch, and then the undercoat layer was dried at 130 ° C., the charge generation layer was 95 ° C., and the charge transport layer was dried at 120 ° C. for 20 minutes.

[Coating liquid for undercoat layer]
-Alkyd resin: 14 parts (Beckolite M-6401-50, solid content: 50% by mass, manufactured by DIC Corporation)
Melamine resin: 8 parts (Super Becamine L-145-60, solid content: 60% by mass, manufactured by DIC Corporation)
Titanium oxide: 50 parts (CR-EL, average primary particle size: 0.25 μm, particle density: 4.3 g / cm ³ , manufactured by Ishihara Sangyo Co., Ltd.)
・ Methyl ethyl ketone 70 parts

[Coating liquid for charge generation layer]
Polyvinyl butyral (BX-1, Sekisui Chemical Co., Ltd.) 10 parts Titanyl phthalocyanine crystal 15 parts Methyl ethyl ketone 280 parts Preparation of coating solution for charge generation layer
Using bead mill disperser (Dispermat SL, manufactured by VMA-Getzmann), using PSZ balls (Traceram, manufactured by Toray Industries, Inc.) with a diameter of 0.5 mm, methyl ethyl ketone and titanyl phthalocyanine crystal in which polyvinyl butyral is dissolved are introduced, and the rotor rotates. Formula 1,200 r. p. m. For 30 minutes to prepare a charge generation layer coating solution.

[Coating liquid for charge transport layer]
・ Bisphenol Z-type polycarbonate 10 parts (Panlite TS-2050, manufactured by Teijin Chemicals Ltd.)
-Charge transporting compound of the following structural formula (1) ... 7 parts-Tetrahydrofuran ... 68 parts-Tetrahydrofuran solution of 1 mass% silicone oil ... 0.2 parts (KF50-1CS, Shin-Etsu Chemical Co., Ltd.) Made)

[Coating process of surface protective layer]
On the laminate having the conductive support, the undercoat layer, the charge generation layer, and the charge transport layer in this order, the surface protection layer coating solution 1 having the following composition is charge transported under the following coating conditions 1. The coating was sprayed once on the layer. Further, a surface protective layer having an average thickness of 4.0 μm was formed by spraying the surface protective layer coating solution 2 having the following composition once by coating under the following coating conditions 2.

[Coating liquid 1 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
Γ-type alumina (aluminum oxide) fine particles: 20 parts (NanoTek Powder Al ₂ O ₃ , average primary particle size: 31 nm, manufactured by CI Kasei Co., Ltd.)
・ Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 2 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Α-type alumina fine particle 20 parts (Sumicorundum (registered trademark) AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

-Coating conditions 1
・ Spray gun-photoreceptor distance: 60mm
-Laminate rotation speed: 100 rpm
・ Spray gun moving speed: 30mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s
-Coating conditions 2-
・ Spray gun-photoreceptor distance: 30mm
-Laminate rotation speed: 100 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

[UV irradiation and drying process]
While rotating the laminate on which the surface protective layer was formed, an ultraviolet lamp (bulb type: H bulb, manufactured by Fusion UV Systems) was used, and the lamp output was 200 W / cm, the illuminance was 450 mW / cm ² , and the irradiation time was 30 seconds. The surface protective layer was crosslinked by irradiating with light under the conditions. Next, the film was dried at 130 ° C. for 30 minutes to produce an electrophotographic photoreceptor 1 (OPC1).

<Example 2>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the coating liquid 2 for surface protective layer used in Example 1 was changed to the following coating condition (coating condition 3). Photoreceptor 2 (OPC2) was produced.
-Coating conditions 3-
・ Spray gun-photoreceptor distance: 40mm
-Laminate rotation speed: 100 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Example 3>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the surface protective layer coating liquid 2 used in Example 1 was changed to the following coating condition (coating condition 4). A photoconductor 3 (OPC3) was produced.
-Coating conditions 4-
・ Spray gun-photoreceptor distance: 20mm
-Laminate rotation speed: 100 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Example 4>
In the same manner as in Example 1, except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the following surface protective layer coating solutions 3 and 4, respectively, the electrophotographic photoreceptor 4 ( OPC4) was produced.
[Coating liquid 3 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Tin oxide fine particles: 20 parts (SN-100P, average primary particle size: 20 nm, manufactured by Ishihara Sangyo Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 4 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Titanium oxide fine particles: 20 parts (ET-300W, average primary particle size: 45 nm, manufactured by Ishihara Sangyo Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 5>
An electrophotographic photoreceptor 5 (OPC5) was produced in the same manner as in Example 1 except that the surface protective layer coating solution 2 used in Example 1 was changed to the following surface protective layer coating solution 5.
[Coating liquid 5 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Titanium oxide fine particles: 20 parts (PT-501A, average primary particle size: 0.1 μm, manufactured by Ishihara Sangyo Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 6>
In the same manner as in Example 1, except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the following surface protective layer coating solutions 6 and 7, respectively, the electrophotographic photoreceptor 6 ( OPC6) was produced.
[Coating liquid 6 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Zinc oxide fine particles: 20 parts (NanoTek Powder ZnO, average primary particle size: 34 nm, manufactured by CII Kasei Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 7 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Α-type alumina fine particle 20 parts (Sumicorundum AA-05, average primary particle size: 0.5 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 7>
In the same manner as in Example 1 except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the following surface protective layer coating solutions 8 and 9, respectively, an electrophotographic photoreceptor 7 ( OPC7) was produced.
[Coating liquid 8 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Tin oxide fine particles: 20 parts (S-2000, average primary particle size: 30 nm, manufactured by Mitsubishi Materials Corporation)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 9 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Α-type alumina fine particle 20 parts (Sumicorundum AA-05, average primary particle size: 0.5 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 8>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the surface protective layer coating solution 2 used in Example 1 was changed to the following coating condition (coating condition 5). A photoconductor 8 (OPC8) was produced.
-Coating conditions 5-
・ Spray gun-photoreceptor distance: 30mm
-Laminate rotation speed: 150 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Example 9>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the surface protective layer coating solution 2 used in Example 1 was changed to the following coating condition (coating condition 6), A photoconductor 9 (OPC9) was prepared.
-Coating conditions 6
・ Spray gun-photoreceptor distance: 30mm
-Laminate rotation speed: 125 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Example 10>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the coating solution 2 for surface protective layer used in Example 1 was changed to the following coating condition (coating condition 7). A photographic photoreceptor 10 (OPC10) was produced.
-Coating condition 7-
・ Spray gun-photoreceptor distance: 30mm
-Laminate rotation speed: 75 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Example 11>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the surface protective layer coating liquid 2 used in Example 1 was changed to the following coating condition (coating condition 8). A photoconductor 11 (OPC11) was produced.
-Coating conditions 8-
・ Spray gun-photoreceptor distance: 30mm
-Laminate rotation speed: 50 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Example 12>
In the same manner as in Example 1, except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the following surface protective layer coating solutions 10 and 11, respectively. OPC12) was produced.
[Coating liquid 10 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Cerium oxide fine particles: 20 parts (NanoTek Powder CeO ₂ , average primary particle size: 12 nm, CI Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 11 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Titanium oxide fine particles: 20 parts (PT-501A, average primary particle size: 0.1 μm, manufactured by Ishihara Sangyo Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 13>
In the same manner as in Example 1, except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the following surface protective layer coating solutions 12 and 13, respectively, the electrophotographic photoreceptor 13 ( OPC13) was produced.
[Coating liquid 12 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Tin oxide fine particles: 20 parts (SN-100P, average primary particle size: 20 nm, Ishihara Sangyo Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 13 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Titanium oxide fine particles: 20 parts (CR-EL, average primary particle size: 0.25 μm, manufactured by Ishihara Sangyo Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 14>
In the same manner as in Example 1, except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the following surface protective layer coating solutions 14 and 15, respectively. OPC14) was produced.
[Coating liquid 14 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Titanium oxide fine particles: 20 parts (NanoTek Powder TiO ₂ , average primary particle size: 36 nm, CII Kasei Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 15 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Α-type alumina fine particles 20 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 15>
In the same manner as in Example 1, except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the following surface protective layer coating solutions 16 and 17, respectively, the electrophotographic photoreceptor 15 ( OPC15) was produced.
[Coating liquid 16 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Titanium oxide fine particles: 20 parts (ET-300W, average primary particle size: 45 nm, Ishihara Sangyo Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts [Coating liquid 17 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Α-type alumina fine particles: 20 parts (Sumicorundum AA-05, average primary particle size: 0.5 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 16>
An electrophotographic photoreceptor 16 (OPC16) was produced in the same manner as in Example 1 except that the surface protective layer coating solution 2 used in Example 1 was changed to the following surface protective layer coating solution 18.
[Coating liquid 18 for surface protective layer]
Acrylic monomer: 10 parts (ethoxylated pentaerythritol tetraacrylate, functional group number: 4, ATM-35E, manufactured by Shin-Nakamura Chemical Co., Ltd.)
-Α-type alumina fine particles 20 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 17>
An electrophotographic photoreceptor 17 (OPC 17) was produced in the same manner as in Example 1 except that the surface protective layer coating solution 2 used in Example 1 was changed to the following surface protective layer coating solution 19.
[Coating liquid 19 for surface protective layer]
Acrylic monomer: 10 parts (dipentaerythritol penta and hexaacrylate, functional group number: 6, DPHA M-402, manufactured by Toagosei Co., Ltd.)
-Α-type alumina fine particles 20 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 18>
An electrophotographic photoreceptor 18 (OPC18) was produced in the same manner as in Example 1 except that the surface protective layer coating solution 2 used in Example 1 was changed to the following surface protective layer coating solution 20.
[Coating liquid 20 for surface protective layer]
・ Acrylic monomer: 10 parts (Hexanediol diacrylate, functional group number: 2, HDDA, manufactured by Daicel-Cytec Corporation)
-Α-type alumina fine particles 20 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Example 19>
Similar to Example 1, except that the surface protective layer coating solution 2 used in Example 1 was changed to the following surface protective layer coating solution 21 and heated at 150 ° C. for 30 minutes to form a crosslinked film. Thus, an electrophotographic photoreceptor 19 (OPC19) was produced.
[Coating liquid 21 for surface protective layer]
-Phenol resin: 12.5 parts (phenol resin, PR-50404, solid content: 80% by mass, manufactured by Sumitomo Bakelite Co., Ltd.)
-Α-type alumina fine particles 20 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Comparative Example 1>
An electrophotographic photoreceptor 20 (OPC20) was produced in the same manner as in Example 1, except that the surface protective layer coating solution 2 used in Example 1 was changed to the following surface protective layer coating solution 22.
[Coating liquid 22 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Comparative example 2>
An electrophotographic photoreceptor 21 (OPC21) was prepared in the same manner as in Example 1 except that the surface protective layer coating solution 1 used in Example 1 was changed to the following surface protective layer coating solution 23.
[Coating liquid 23 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Comparative Example 3>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the surface protective layer coating liquid 2 used in Example 1 was changed to the following coating condition (coating condition 9). A photoconductor 22 (OPC22) was produced.
-Coating conditions 9-
・ Spray gun-photoreceptor distance: 50mm
-Laminate rotation speed: 100 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Comparative example 4>
In the same manner as in Example 1, except that the coating condition (coating condition 2) of the surface protective layer coating solution 2 used in Example 1 was changed to the following coating condition (coating condition 10). A photoconductor 23 (OPC23) was produced.
-Coating conditions 10-
・ Spray gun-photoreceptor distance: 10mm
-Laminate rotation speed: 100 rpm
・ Spray gun moving speed: 45mm / s
Spray gun atomization pressure: 1.5 kgf / cm ²
・ Spray gun coating amount: 1cc / s

<Comparative Example 5>
An electrophotographic photoreceptor 24 (OPC24) was produced in the same manner as in Example 1 except that the surface protective layer coating solution 2 used in Example 1 was changed to the following surface protective layer coating solution 24.
[Coating liquid 24 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
Γ-type alumina (aluminum oxide) fine particles: 20 parts (NanoTek Powder Al ₂ O ₃ , average primary particle size: 31 nm, manufactured by CI Kasei Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Comparative Example 6>
An electrophotographic photoreceptor 25 (OPC25) was produced in the same manner as in Example 1 except that the surface protective layer coating solution 1 used in Example 1 was changed to the following surface protective layer coating solution 25.
[Coating liquid 25 for surface protective layer]
-Acrylic monomer: 10 parts (Trimethylolpropane triacrylate, functional group number: 3, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.)
-Α-type alumina fine particles 20 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) 0.5 part (Irgacure 184, manufactured by BASF Japan Ltd.)
・ Tetrahydrofuran ・ ・ ・ 180 parts

<Comparative Example 7>
The electrophotographic photosensitive member 26 (OPC26) was obtained in the same manner as in Example 1 except that the surface protective layer coating solutions 1 and 2 used in Example 1 were changed to the surface protective layer coating solutions 25 and 24, respectively. ) Was produced.

Table 1 shows an outline of the structure of the produced electrophotographic photosensitive member (OPC1 to OPC26).

(Measurement of surface uneven structure of surface protective layer)
Using a surface roughness meter, the cross-sectional curve is measured under the following conditions, and for the adjacent convex portions, the concave / convex period (distance between adjacent convex portions) and the convex / concave height (the height difference of the concave / convex portions) at any 10 locations. ) And the average values thereof were defined as the average irregularity period and the average irregularity height, respectively.
The measurement was performed by reading the obtained cross-sectional curve graph. When a plurality of adjacent convex portions and uneven heights exist in one sectional curve, all data were obtained and averaged.
The results are shown in Table 2.
Analyzer: Surface roughness meter (Surfcom 1400D, manufactured by Tokyo Seimitsu Co., Ltd.)
Measurement probe: Surfcom pickup E-DT-S01A (manufactured by Tokyo Seimitsu Co., Ltd.)
・ Measurement length: 100mm
・ Measurement speed: 0.3mm / s

(Evaluation)
The following evaluations were performed on the electrophotographic photoreceptors produced in the examples and comparative examples.

<Image (cleaning characteristics) evaluation>
An electrophotographic photosensitive member (OPC1 to OPC26) was attached to imagio MP C4500 (manufactured by Ricoh Co., Ltd.), and an initial image was output. Thereafter, using a copy chart with an image area ratio of 6%, a paper passing test of 100,000 sheets was performed on the side of A4 paper, and the image after long-term use was confirmed to evaluate the image. The results are shown in Table 2.

<Evaluation of electrical characteristics (exposed portion potential)>
After the 100,000 sheet passing test, an electric potential measuring jig was installed in an imagio MP C4500 (manufactured by Ricoh Co., Ltd.), and a solid image was written on the entire surface to measure the exposed portion potential. The results are shown in Table 2.

<Abrasion durability evaluation>
The amount of wear was measured by measuring the thickness of the electrophotographic photoreceptor before and after the 100,000 sheet passing test using an eddy current film thickness meter (FISHERSCOPE MMS, manufactured by Fischer Instruments). The results are shown in Table 2.

  In the electrophotographic photoreceptor of the present invention, the surface of the surface protective layer has an uneven structure, and in the surface protective layer, metal oxide fine particles having a large average primary particle diameter are present in the vicinity of the boundary with the photosensitive layer. Since there are metal oxide part particles with a small average primary particle size, the advantages and uniform distribution of the metal oxide fine particles with large particle size that have high wear resistance and inactive and stable characteristics are possible. It is possible to combine the advantages of a metal oxide with a small particle diameter that exhibits excellent electrical properties at the interface between the photosensitive layer and the surface protective layer, resulting in excellent cleaning properties, durability, and electrical properties. Is shown.

The aspect of the present invention is as follows.
<1> An electrophotographic photosensitive member having a conductive support and at least a photosensitive layer and a surface protective layer in this order on the conductive support, wherein the surface protective layer includes a binder resin and metal oxide fine particles. Containing
In the surface protective layer, the average primary particle diameter of the metal oxide fine particles present in the vicinity of the surface is larger than the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer,
The surface of the surface protective layer has an uneven structure,
The electrophotographic photosensitive member is characterized in that an average concavo-convex height of the concavo-convex structure is 0.5 μm or more and 2 μm or less.
<2> In the surface protective layer, the average primary particle diameter of the metal oxide fine particles present in the vicinity of the surface is 5 times the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer. The electrophotographic photosensitive member according to <1>, which is 10 times or less.
<3> The electrophotographic photosensitive member according to any one of <1> to <2>, wherein the uneven structure has an average unevenness period of 10 mm to 50 mm.
<4> The electrophotography according to any one of <1> to <3>, wherein in the surface protective layer, the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer is 10 nm or more and 50 nm or less. It is a photoreceptor.
<5> The electron according to any one of <1> to <4>, wherein the surface protective layer is composed of two layers, and the binder resin of the surface side layer is a cured resin obtained by curing an acrylic monomer having 3 or more functional groups. It is a photographic photoreceptor.
<6> An electrophotographic photosensitive member, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that exposes the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image An image having at least developing means for developing a visible image by developing with toner, transfer means for transferring the visible image to a recording medium, and cleaning means for removing toner remaining on the electrophotographic photosensitive member A forming device,
An electrophotographic photosensitive member according to any one of <1> to <5>, wherein the electrophotographic photosensitive member is an image forming apparatus.
<7> The image forming apparatus according to <6>, wherein the cleaning unit includes a strip-shaped elastic blade, and removes the toner by bringing a tip ridge line portion of the elastic blade into contact with the surface of the electrophotographic photosensitive member.
<8> An electrophotographic photosensitive member, charging means for charging the surface of the electrophotographic photosensitive member, exposure means for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image At least one of developing means for developing a visible image by developing toner, transfer means for transferring the visible image to a recording medium, and cleaning means for removing toner remaining on the electrophotographic photosensitive member A process cartridge having such means,
A process cartridge, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of <1> to <5>.
<9> The apparatus according to <8>, further including a cleaning unit, wherein the cleaning unit includes a strip-shaped elastic blade, and removes the toner by bringing a tip ridge line portion of the elastic blade into contact with the surface of the electrophotographic photosensitive member. This is a process cartridge.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photosensitive member 3 Charging means 5 Exposure means 6 Developing means 10 Transfer means 21 Conductive support body 23 Charge generation layer 24 Charge transport layer 25 Surface protective layer 26 Single layer type photosensitive layer 101 Electrophotographic photosensitive member 102 Charging means 104 Development Means 106 Transfer means

Japanese Patent No. 4590308 JP 2003-156865 A JP 2011-145457 A

Claims (9)

An electrophotographic photoreceptor having a conductive support and at least a photosensitive layer and a surface protective layer in this order on the conductive support, wherein the surface protective layer contains a binder resin and metal oxide fine particles. ,
In the surface protective layer, the average primary particle diameter of the metal oxide fine particles present in the vicinity of the surface is larger than the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer,
The surface of the surface protective layer has an uneven structure,
An electrophotographic photosensitive member, wherein an average concavo-convex height of the concavo-convex structure is from 0.5 μm to 2 μm.   In the surface protective layer, the average primary particle diameter of the metal oxide fine particles present in the vicinity of the surface is 5 to 10 times the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer. The electrophotographic photosensitive member according to claim 1, wherein:   The electrophotographic photosensitive member according to claim 1, wherein the concavo-convex structure has an average concavo-convex period of 10 mm or more and 50 mm or less.   The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein in the surface protective layer, the average primary particle diameter of the metal oxide fine particles present in the vicinity of the boundary with the photosensitive layer is 10 nm or more and 50 nm or less.   The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the surface protective layer comprises two layers, and the binder resin of the surface layer is a cured resin obtained by curing an acrylic monomer having 3 or more functional groups. An electrophotographic photosensitive member, a charging means for charging the surface of the electrophotographic photosensitive member, an exposure means for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image using toner An image forming apparatus having at least developing means for forming a visible image by developing, a transfer means for transferring the visible image to a recording medium, and a cleaning means for removing toner remaining on the electrophotographic photosensitive member. There,
An image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.   The image forming apparatus according to claim 6, wherein the cleaning unit includes a strip-shaped elastic blade, and removes the toner by bringing a tip ridge line portion of the elastic blade into contact with the surface of the electrophotographic photosensitive member. An electrophotographic photosensitive member; charging means for charging the surface of the electrophotographic photosensitive member; exposure means for exposing the charged surface of the electrophotographic photosensitive member to form an electrostatic latent image; At least one of developing means for forming a visible image by using the developing means, transfer means for transferring the visible image to a recording medium, and cleaning means for removing toner remaining on the electrophotographic photosensitive member A process cartridge having
A process cartridge, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.   The process cartridge according to claim 8, further comprising a cleaning unit, wherein the cleaning unit includes a strip-shaped elastic blade, and removes the toner by bringing a tip ridge line portion of the elastic blade into contact with the surface of the electrophotographic photosensitive member.