JP2016057595A - Electrophotographic photoreceptor, image forming apparatus, and cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that has excellent electrical characteristics, excellent adhesive properties, and excellent wear resistance in various use environments from high temperature and high humidity to low temperature and low humidity, an image forming apparatus, and a cartridge.SOLUTION: There is provided an electrophotographic photoreceptor that has an undercoat layer and a photosensitive layer on a conductive support, where the undercoat layer contains a binder resin, and metal oxide particles each having a surface treated with an organic metal compound having the following structural formula (I), and the photosensitive layer contains a polyarylate resin having the structural formula (II). The structural formula (I): CH=CR-COO-R-M.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photosensitive member having an undercoat layer. More specifically, the present invention relates to an electrophotographic photosensitive member having good electrical characteristics, including wear resistance and adhesion, including initial and repeated low temperature and low humidity to high temperature and high humidity. It is about the body.

  In recent years, electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers because of its immediacy and high-quality images. As for photoconductors that are the core of electrophotographic technology, in recent years, photoconductors using organic photoconductive materials that have the advantages of non-polluting, easy film formation, easy manufacture, etc. Has been developed. In particular, a stacked type photoconductor composed of a charge generation layer and a charge transfer layer that separates the function of absorbing light to generate charges and the function of transporting the generated charges has become the mainstream. Currently, these photoreceptors are widely used in the field of image forming apparatuses such as copying machines and laser printers.

The electrophotographic photosensitive member has a basic structure in which a photosensitive layer is formed on a conductive support. An undercoat layer is provided between the photosensitive layer and the support in order to eliminate image defects due to charge injection from the support or defects in the support, improve adhesion to the photosensitive layer, and improve chargeability. Yes.
As the undercoat layer, various resin materials are known to be used, and it is known that a soluble polyamide resin is particularly preferable (see Patent Document 1). Further, a copolymerized polyamide resin having a specific diamine component as a constituent component is preferably used (see Patent Document 2). As an undercoat layer in which an inorganic material is dispersed in such a polyamide resin, for example, one in which titanium oxide and tin oxide are dispersed in 8-nylon is known (see cited reference 3), which improves the leak resistance characteristics. For this purpose, it is known to use metal acid compound particles surface-treated with an organometallic compound having an acrylic group (see Patent Document 4).

  On the other hand, various binder resins have been investigated for the photosensitive layer in order to improve the wear resistance. It is known that a polyarylate resin having a specific structure is excellent in wear resistance (see Patent Document 5). However, it is known that when the photosensitive layer contains a polyarylate resin having a specific structure, the adhesiveness deteriorates. To solve this problem, for example, by using a subbing layer having a polyamide resin having a polyether structure, even a photoreceptor having a photosensitive layer having the polyarylate resin can maintain good adhesion ( (See Patent Document 6).

JP 56-21129 A JP-A-4-31870 Japanese Patent Laid-Open No. 62-280864 JP 2012-88430 A JP 2006-53549 A JP 2014-44417 A

However, in the undercoat layer described in Patent Document 6, although the adhesiveness is improved, the electrical characteristics in a high temperature and high humidity environment, particularly the repeated electrical characteristics in a high temperature and high humidity state may be deteriorated, and the polylayer having a specific structure is deteriorated. When an arylate resin is used, the electrophotographic photoreceptor using the previously known undercoat layer cannot achieve both electrical properties and adhesiveness in a high temperature and high humidity environment. That is, the present invention is an electrophotographic photosensitive member and image forming that are excellent in electrical characteristics, excellent in adhesion, and excellent in abrasion resistance both in the initial stage and repeatedly under various usage environments ranging from high temperature and high humidity to low temperature and low humidity. An object is to provide an apparatus and a cartridge.

As a result of intensive studies on materials used for the undercoat layer in the electrophotographic photoreceptor containing the polyarylate resin having the structural formula (II), the present inventors have found that the surface of the organometallic compound having the structural formula (I) The photoreceptor using the treated metal acid compound particles and the undercoat layer containing the binder resin was found to be excellent in electrical characteristics and adhesiveness, and reached the present invention. That is, the gist of the present invention resides in the following <1> to <9>.
<1> In an electrophotographic photoreceptor having an undercoat layer and a photosensitive layer on conductivity, the undercoat layer is a metal oxide particle surface-treated with an organometallic compound having the following structural formula (I): An electrophotographic photoreceptor comprising a binder resin, wherein the photosensitive layer contains a polyarylate resin having the structural formula (II).

Structural formula (I)
_{^{CH 2 = CR 1 -COO-R}} 2 -M

(R ¹ is a hydrogen atom or an alkyl group, R ² is an alkylene group, M is Si (R ³ ) ₃ , Ti (R ³ ) ₃ , or Al (R ³ ) _2. R ³ is alkyl. Represents a group or an alkoxy group.)

(In the formula (II), Ar ^{1 to} Ar ⁴ each independently represents a phenylene group optionally having an alkyl group, and R ³ and R ⁴ represent a hydrogen atom or an alkyl group. R ³ and R ⁴ represent It may be bonded to form a ring.)
<2> The electrophotographic photosensitive member according to <1>, wherein the photosensitive layer is a laminated photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order.
<3> The electrophotographic photosensitive member according to <1> or <2>, wherein R ^{1 in the} structural formula (I) is a methyl group.
<4> The organic metal compound having the structural formula (I) is 5% by mass to 30% by mass with respect to the metal oxide particles, and any one of <1> to <3> The electrophotographic photoreceptor described in 1.
<5> The electrophotographic photosensitive member according to any one of <1> to <4>, wherein the metal oxide particles are n-type semiconductor particles.
<6> The electrophotographic photosensitive film according to any one of <1> to <5>, wherein the metal oxide particles are 100 to 400 parts by mass with respect to 100 parts by mass of the binder resin. body.
<7> The binder resin is a polyamide resin, <1> to <6>
The electrophotographic photosensitive member according to any one of the above.
<8> An image forming apparatus using the electrophotographic photosensitive member according to any one of <1> to <7>. <9> A cartridge for an image forming apparatus using the electrophotographic photosensitive member according to any one of <1> to <7>.

  According to the present invention, in various usage environments ranging from high temperature and high humidity conditions to low temperature and low humidity conditions, even when the polyarylate resin having the structural formula (II) is contained, the adhesion between the photosensitive layer and the conductive substrate. High-performance electrophotographic photosensitive member excellent in electrical characteristics such as chargeability and residual potential, high-performance image forming apparatus using the photosensitive member, and image forming apparatus using the photosensitive member Cartridges can be provided.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and is appropriately modified and implemented without departing from the spirit of the present invention. can do.
<Electrophotographic photoreceptor>
An undercoat layer is formed on the conductive support, and a photosensitive layer is formed on the undercoat layer.

[Conductive support]
There is no particular limitation on the conductive support, but for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powder such as metal, carbon, and tin oxide are added to impart conductivity. A resin material, a resin, glass, paper, or the like on which a conductive material such as aluminum, nickel, or ITO (indium tin oxide) is deposited or applied on the surface is mainly used. These may be used alone or in combination of two or more in any combination and ratio. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Further, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

  Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after giving an anodic oxide film. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method. The surface of the support may be smooth, or may be roughened by using a special cutting method or by performing a roughening treatment. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support. In order to reduce the cost, it is possible to use a centerless polishing process or a drawing tube as it is without performing a cutting process.

[Underlayer]
In the present invention, an undercoat layer containing metal oxide particles surface-treated with an organometallic compound having the structural formula (I) and a binder resin is formed on a conductive support.
Structural formula (I)
_{^{CH 2 = CR 1 -COO-R}} 2 -M
(R ¹ is a hydrogen atom or an alkyl group, R ² is an alkylene group, M is Si (R ³ ) ₃ , Ti (R ³ ) ₃ , or Al (R ³ ) _2. R ³ is alkyl. Represents a group or an alkoxy group.)
In the structural formula (I), as the alkyl group of R ^1, a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, an i-propyl group, a t-butyl group, and an ethylhexyl group And a cyclic alkyl group such as a cyclohexyl group. From the viewpoint of adhesiveness, an alkyl group having 3 or less carbon atoms is preferable, and a methyl group is more preferable. Examples of the alkylene group for R ² include a methylene group, an ethylene group, an n-propylene group, and an n-butylene group. From the viewpoint of adhesiveness, an alkylene group having 4 or less carbon atoms is preferable. More preferably, it is a group. Examples of the alkoxy group for R ³ include linear alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, and n-butoxy group, branched alkoxy groups such as isopropoxy group and ethylhexyloxy group, and cyclohexyloxy group. And an alkoxy group having a fluorine atom, such as a cyclic alkoxy group, a trifluoromethoxy group, a pentafluoroethoxy group, and a 1,1,1-trifluoroethoxy group, and those exemplified for R ¹ are applicable. From the viewpoint of adhesiveness, an alkoxy group having 3 or less carbon atoms is preferable, and an ethoxy group or a methoxy group is more preferable. The organometallic compound having the structural formula (I) is preferably a silane coupling agent. Among the organometallic compounds, 3-methacryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane are particularly preferable from the viewpoints of electrical characteristics and adhesiveness.

  As the metal oxide particles, those having high dispersion stability of the coating liquid are preferable. Specific examples include silica, alumina, titanium oxide, barium titanate, zinc oxide, lead oxide, indium oxide, and the like. Among these, from the viewpoint of electrical characteristics, metal oxide particles exhibiting n-type semiconductor characteristics are preferable, titanium oxide, zinc oxide, and tin oxide are more preferable, and titanium oxide is more preferable.

As the titanium oxide, either crystalline or amorphous can be used. In the case of crystalline, the crystalline form may be any of anatase type, rutile type or brookite type. It is preferable to use an anatase type or rutile type, and it is more preferable to use a rutile type.
The average primary particle size of the metal oxide particles is usually 100 nm or less, preferably 60 nm or less, and particularly preferably 40 nm or less, from the viewpoint of dispersion stability in the coating solution. From the viewpoint of suppressing aggregation, the lower limit is 1 nm or more, preferably 10 nm or more, and particularly preferably 20 nm or more. The particle size of the particles used in the coating solution may be uniform or a composite system having different particle sizes. For example, a mixture having an average primary particle diameter of 100 m and 30 nm may be used.

  The metal oxide particles treated with the organometallic compound having the structural formula (I) of the present invention (hereinafter sometimes referred to as a surface treating agent) can be produced by a dry process and a wet process. That is, in the dry method, the surface treatment agent of the present invention can be produced by a method in which metal oxide particles are coated by mixing with the metal oxide particles, and heat treatment is performed as necessary. In the wet method, the metal oxide particles and a mixture of the surface treatment agent of the present invention mixed with an appropriate solvent are thoroughly stirred until they are uniformly attached or mixed with media, and then dried, if necessary. It can manufacture by the method of heat-processing.

  By treating with the surface treatment agent of the present invention, the organometallic compound having the structural formula (I) is firmly bonded to the surface of the metal oxide particles, and the dispersion stability of the coating liquid containing the particles, low water absorption, good Delivers excellent electrical properties. As for the amount of the surface treatment agent, when the treatment amount is small, the effect of the present invention cannot be obtained. This may cause film repelling. Therefore, the lower limit is usually 1 part by mass or more, preferably 5 parts by mass or more, and more preferably 10 parts by mass or more with respect to 100 parts by mass of the metal oxide particles used. From the viewpoint of electrical characteristics, the upper limit is usually 50 parts by mass or less, preferably 30 parts by mass or less, and more preferably 20 parts by mass or less.

  As the binder resin for the undercoat layer, resin materials such as polyvinyl acetal, polyamide resin, phenol resin, polyester, epoxy resin, polyurethane, and polyacrylic acid can be used. Among these, a polyamide resin having excellent adhesion to the support and low solubility in a solvent used for the charge generation layer coating solution is preferable. Among the polyamide resins, a copolymer polyamide having a cycloalkane ring structure as a constituent component is preferable, and a copolymer polyamide having a cyclohexane ring structure as a constituent component is more preferable, and among them, the following structural formula (III) is particularly preferable. A copolymerized polyamide resin having a diamine component as a constituent material is preferable.

(In Formula (III), A and B each independently represent a cyclohexane ring which may have a substituent, and X represents a methylene group which may have a substituent.)
The ratio between the metal oxide particles treated with the surface treatment agent and the binder resin is usually 50 parts by mass or more and preferably 100 parts by mass or more with respect to 100 parts by mass of the binder resin in terms of electrical characteristics. The upper limit is usually 800 parts by mass or less, preferably 400 parts by mass or less, from the viewpoint of liquid stability and applicability. The undercoat layer is mainly composed of metal oxide particles coated with an organometallic compound having the structural formula (I) and a binder resin, but if necessary, other surface-treated metal acid compound particles (fluorine silane treatment). In addition, it is preferable to add methyldimethoxysilane-treated titanium oxide from the viewpoint of transferability. Moreover, you may add metal compound particle | grains without surface treatment, antioxidant, an additive, a electrically conductive agent, etc.

If the film thickness of the undercoat layer is too thin, the effect on local charging failure will not be sufficient, and conversely if it is too thick, the residual potential will increase or the adhesive strength between the conductive substrate and the photosensitive layer will decrease. Cause. In the present invention, the thickness of the undercoat layer is from 0.1 to 20 μm, more preferably from 0.5 to 10 μm, still more preferably from 1 to 5 μm. The volume resistance value of the undercoat layer is usually 1 × 10 ¹¹ Ω · cm or more, preferably 1 × 10 ¹² Ω · cm or more, and usually 1 × 10 ¹⁴ Ω · cm or less, preferably 1 × 10 ¹³ Ω · cm. cm or less.

In order to obtain an undercoat coating solution containing metal oxide particles coated with an organometallic compound having the structural formula (I) and a binder resin, a planetary mill, a ball mill, a sand mill, a bead mill, a paint shaker, an attritor, What is necessary is just to mix and stir the slurry of the metal oxide particle processed with the grinding | pulverization or dispersion processing apparatuses, such as an ultrasonic wave, and the binder resin solution which melt | dissolved binder resin in the appropriate solvent previously. It can also be obtained by adding a binder resin to the metal oxide slurry and dissolving it. Moreover, it is also possible to disperse using small-diameter beads as described in Japanese Patent No. 4949893. Furthermore, metal oxide particles may be added to the binder resin solution, and pulverization or dispersion treatment may be performed using the above-described dispersion apparatus.

[Photosensitive layer]
As a type of the photosensitive layer, a charge generation material and a charge transport material are present in the same layer and are dispersed in a binder resin, a charge generation layer in which a charge generation material is dispersed in a binder resin, and a charge. A functional separation type (laminated type) composed of two layers of a charge transporting layer in which a transport material is dispersed in a binder resin can be mentioned, and it is a laminated type photosensitive layer in which a charge generation layer and a charge transporting layer are laminated in this order. In some cases, the adhesion is particularly improved by using the undercoat layer. In addition, the multilayer photosensitive layer is preferably a sequential multilayer photosensitive layer in which a charge generation layer and a charge transport layer are stacked in this order from the conductive support side. For the purpose of improving film forming properties, flexibility, coating properties, contamination resistance, gas resistance, light resistance, etc., in both the photosensitive layer and the layers constituting the photosensitive layer, both of the multilayer type photosensitive member and the single layer type photosensitive member. Additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents may be included.

[Laminated Photosensitive Layer-Charge Generation Layer]
In the case of a laminated type photoreceptor (function separation type photoreceptor), the charge generation layer is formed by binding a charge generation material with a binder resin. Examples of the charge generation material include inorganic photoconductive materials such as selenium and its alloys, cadmium sulfide, and organic photoconductive materials such as organic pigments, but organic photoconductive materials are preferred, especially organic pigments. Is preferred. Examples of organic pigments include phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. . Among these, phthalocyanine pigments or azo pigments are particularly preferable. When organic pigments are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

  When using a phthalocyanine pigment as a charge generation material, specifically, metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum or other metal or oxide thereof, halide, water Those having crystal forms of coordinated phthalocyanines such as oxides and alkoxides, and phthalocyanine dimers using oxygen atoms as bridging atoms are used. In particular, titanyl phthalocyanines (also known as oxytitanium) such as X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), and D-type (also known as Y-type), which are highly sensitive crystal types Phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, hydroxyindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, type II, etc. The [mu] -oxo-aluminum phthalocyanine dimer is preferred.

  Among these phthalocyanines, A-type (also known as β-type), B-type (also known as α-type), and powder X-ray diffraction angle 2θ (± 0.2 °) are 27.1 ° or 27.3 °. D-type (Y-type) titanyl phthalocyanine, II-type chlorogallium phthalocyanine, V-type and 28.1 ° have the strongest peaks, and 26.2 ° have peaks Hydroxygallium phthalocyanine having a clear peak at 28.1 ° and a full width at half maximum W of 25.9 ° of 0.1 ° ≦ W ≦ 0.4 °, G-type μ-oxo -Gallium phthalocyanine dimer and the like are particularly preferable.

  The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state that can be put in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or they may be mixed in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, and crystallization. It may be the one that caused the condition. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known. In order to generate a mixed crystal state, as described in JP-A-10-48859, two types of crystals are mixed, mechanically ground and made amorphous, and then converted into a specific crystal state by solvent treatment. The method of doing is mentioned.

The binder resin used for the charge generation layer is not particularly limited, but examples include polyvinyl butyral resin, polyvinyl formal resin, polyvinyl acetal type such as partially acetalized polyvinyl butyral resin in which a part of butyral is modified with formal, acetal, or the like. Resin, Polyarylate resin, Polycarbonate resin, Polyester resin, Modified ether type polyester resin, Phenoxy resin, Polyvinyl chloride resin, Polyvinylidene chloride resin, Polyvinyl acetate resin, Polystyrene resin, Acrylic resin, Methacrylic resin, Polyacrylamide resin, Polyamide Resin, polyvinyl pyridine resin, cellulosic resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, vinyl chloride -Vinyl acetate-vinyl acetate copolymers such as vinyl acetate copolymers, hydroxy-modified vinyl chloride-vinyl acetate copolymers, carboxyl-modified vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, etc. Insulating resins such as polymers, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, styrene-alkyd resins, silicon-alkyd resins, phenol-formaldehyde resins, poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl Examples include organic photoconductive polymers such as perylene, and polyvinyl acetal resins are particularly preferable, and polyvinyl acetal resins are preferably polyvinyl butyral resins from the viewpoint of dispersibility. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.

  In the charge generation layer, the mixing ratio (mass) of the binder resin and the charge generation material is usually 10 parts by mass or more, preferably 30 parts by mass or more, and usually 1000 parts by mass with respect to 100 parts by mass of the binder resin. Part or less, preferably 500 parts by mass or less, and the film thickness is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material, while if the ratio of the charge generation material is too low, the sensitivity as a photoreceptor may be decreased. There is. It is effective to refine the particles to a particle size in the range of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

[Laminated Photosensitive Layer-Charge Generation Layer]
The charge transport layer of the multilayer photoreceptor contains a charge transport material and a binder resin. Furthermore, you may contain another component as needed. It can be obtained by dissolving or dispersing the charge transport material and the binder resin in a solvent to prepare a coating solution, and coating and drying on the charge generation layer. In the case of a laminated type photoreceptor, a polyarylate resin having the following structural formula (II) is contained in the charge transport layer.

(In the formula (II), Ar ^{1 to} Ar ⁴ each independently represents a phenylene group optionally having an alkyl group, and R ³ and R ⁴ represent a hydrogen atom or an alkyl group. R ³ and R ⁴ represent It may be bonded to form a ring.)
Examples of the alkyl group that Ar ^{1 to} Ar ⁴ may have include a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, an i-propyl group, a t-butyl group, Examples thereof include a branched alkyl group such as an ethylhexyl group and a cyclic alkyl group such as a cyclohexyl group. From the viewpoint of electrical characteristics, an alkyl group having 3 or less carbon atoms is preferable, and a methyl group is more preferable. From the viewpoint of electrical characteristics, Ar ¹ and Ar ² do not have an alkyl group, Ar ³ ,
Ar ⁴ preferably has an alkyl group. As the alkyl group for R ³ and R ⁴ , those exemplified as the alkyl group that Ar ^{1 to} Ar ⁴ may have are applicable. From the viewpoint of wear resistance, R ³ is a hydrogen atom, and R ⁴ is methyl. It is preferably a group. Specific examples are shown below.

  The polyarylate resin having the structural formula (II) is usually 50% by mass or more and preferably 80% by mass or more with respect to the total binder resin of the charge transport layer from the viewpoint of wear resistance. Other binder resins may be included as necessary. Examples of such binder resins include polymers and copolymers of vinyl compounds such as butadiene resins, styrene resins, vinyl acetate resins, vinyl chloride resins, acrylic ester resins, methacrylic ester resins, vinyl alcohol resins, and ethyl vinyl ethers. , Polyvinyl butyral resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyester resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicon resin, silicon-alkyd resin, poly-N-vinylcarbazole resin, structure Examples include polyarylate resin having no formula (II). Of these, polyarylate resins and polycarbonate resins are preferred from the viewpoint of compatibility.

  The charge transport material is not particularly limited, and any material can be used. Examples of known charge transport materials include aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, electron withdrawing materials such as quinone compounds such as diphenoquinone, and carbazole derivatives. , Indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives and multiple types of these compounds Or an electron donating substance such as a polymer having a group composed of these compounds in the main chain or side chain. Among these, from the viewpoint of electrical properties, carbazole derivatives, tertiary aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and those in which a plurality of these compounds are combined are preferred, enamine derivatives, tertiary aromatics. Amine derivatives are particularly preferred. Any one of these charge transport materials may be used alone, or two or more thereof may be used in any combination. Specific examples of the structure are shown below.

  Among the charge transport materials, the hole transport material is preferably a compound having the following structure from the viewpoint of residual potential.

  Among the charge transport materials, the electron transport material is preferably a compound having the following structure from the viewpoint of sensitivity.

As a ratio of the binder resin and the charge transport material, the charge transport material is usually used at a ratio of 10 parts by mass or more with respect to 100 parts by mass of the binder resin. Among these, 20 parts by mass or more is preferable from the viewpoint of reducing the residual potential, and 30 parts by mass or more is more preferable from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, the charge transport material is usually used at a ratio of 100 parts by mass or less. Among them, 70 parts by mass or less is preferable from the viewpoint of compatibility between the charge transport material and the binder resin, 60 parts by mass or less is more preferable from the viewpoint of wear resistance, and 50 parts by mass or less is particularly preferable from the viewpoint of scratch resistance.
The thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 15 μm or more from the viewpoint of high resolution, and is usually 30 μm or less, preferably 25 μm or less from the viewpoint of long life and image stability.

[Single-layer type photosensitive layer]
The single-layer type photosensitive layer is formed by using a polyarylate resin having the structural formula (II) as a binder resin in the same manner as the charge transport layer of the multilayer photoreceptor in addition to the charge generation material and the charge transport material. Specifically, the charge generation material, the charge transport material, and the polyarylate resin can be dissolved or dispersed in a solvent to prepare a coating solution, which can be applied to the undercoat layer and dried.

  The types of charge transport materials and the usage ratios of the charge transport material and the binder resin are the same as those described for the charge transport layer of the multilayer photoreceptor. A charge generating material is further dispersed in a charge transport medium comprising these charge transport materials and a binder resin. As the charge generation material, the same materials as those described for the charge generation layer of the multilayer photoreceptor can be used. However, in the case of a photosensitive layer of a single-layer type photoreceptor, it is necessary to sufficiently reduce the particle size of the charge generating material. Specifically, the range is usually 1 μm or less, preferably 0.5 μm or less. If the amount of the charge generating material dispersed in the single-layer type photosensitive layer is too small, sufficient sensitivity cannot be obtained, but if it is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. It is used in the range of usually 0.5% by mass or more, preferably 1% by mass or more, and usually 50% by mass or less, preferably 20% by mass or less based on the whole layer-type photosensitive layer. In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is the range of 10 mass parts or less. The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.

[Other functional layers]
Further, in both the laminated type photoreceptor and the single layer type photoreceptor, the photosensitive layer formed by the above procedure may be the uppermost layer, that is, the surface layer, but another layer may be provided on the photosensitive layer and used as the surface layer. Good. For example, a protective layer may be provided for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to discharge products generated from a charger or the like. Since the polyarylate resin having the structural formula (II) has good wear resistance, it is preferable that the photosensitive layer is a surface layer in order to make use of its characteristics and to reduce the number of production steps.

[Method for forming each layer]
The undercoat layer of the present invention and each layer constituting the photoconductor are formed by dip coating, spray coating, nozzle coating, bar coating on a support obtained by dissolving or dispersing a substance contained in each layer in a solvent. It is formed by repeating the coating / drying step for each layer in order by a known method such as coating, roll coating, blade coating or the like.

  There are no particular restrictions on the solvent or dispersion medium used in the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene and xylene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1, Chlorinated hydrocarbons such as 2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine , Nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

  The amount of the solvent or dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriate so that the physical properties such as solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust. For example, in the case of a charge transport layer of a single layer type photoreceptor or a function separation type photoreceptor, the solid content concentration of the coating solution is usually 5% by mass or more, usually 5% by mass or more, preferably 10% by mass or more. The range is usually 40% by mass or less, preferably 35% by mass or less. Further, the viscosity of the coating solution is usually in the range of 10 cps or more, preferably 50 cps or more, and usually 500 cps or less, preferably 400 cps or less.

In the case of a charge generation layer of a multilayer photoreceptor, the solid content concentration of the coating solution is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass. % Or less. The viscosity of the coating solution is usually 0.01 cps or more, preferably 0.1 cps or more, and usually 20 cps or less, preferably 10 cps or less.
Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used.

<Image forming apparatus, cartridge>
An image forming apparatus such as a copying machine or a printer using the electrophotographic photosensitive member of the present invention includes at least charging, exposure, development, transfer, and static elimination processes. Also good. As shown in FIG. 1, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, and a developing device 4, and further includes a transfer device 5, a cleaning device 6, and a fixing device as necessary. 7 is provided.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention still in detail, this invention is not limited to these, unless the summary is exceeded. In addition, "part" used in an Example shows a "mass part".

<Manufacture of dispersion for undercoat layer coating formation>
[Coating liquid P1 for forming the undercoat layer]
Rutile white titanium oxide with an average primary particle size of 40 nm (product name: TT, manufactured by Ishihara Sangyo Co., Ltd.)
O55N) and 15 parts of titanium oxide were subjected to a surface treatment by stirring 15 parts of 3-methacryloxypropyltrimethoxysilane with a super mixer until the temperature in the mixer reached 160 ° C. by shearing force. . Next, this surface-treated titanium oxide, methanol and 1-propanol were ball milled with 5 mmφ alumina beads to obtain a titanium oxide dispersion. ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [compound represented by the following formula (B)] / hexamethylenediamine [represented by the following formula (C) Compound] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [compound represented by the following formula (E)] has a composition molar ratio of 60% / 15% / 5%. / 15% / 5% of the copolymerized polyamide pellets was stirred and mixed in a methanol / 1-propanol / toluene mixed solvent with heating to obtain a copolymerized polyamide resin solution. After stirring and mixing the titanium oxide dispersion and the copolymerized polyamide resin solution, an ultrasonic dispersion treatment with an ultrasonic transmitter having a frequency of 25 kHz and an output of 1200 W is performed for 1 hour, and a PTFE membrane filter having a pore size of 5 μm (Mytecs LC manufactured by Advantech). ), The mass ratio of titanium oxide / copolymerized polyamide is 3/1, the mass ratio of the mixed solvent of methanol / 1-propanol / toluene is 7/1/2, and the concentration of the solid content contained Obtained 18.0 mass% undercoat layer forming coating solution P1.

[Undercoat layer forming coating solution P2]
Undercoat forming coating solution P2 was obtained in the same manner as dispersion P1, except that the surface treating agent was changed to methyldimethoxysilane and the amount of surface treating agent was changed to 3 parts.

[Undercoat layer forming coating solution P3]
Mixing 15 parts of 3-methacryloxypropyltrimethoxysilane with shear force against rutile white titanium oxide with an average primary particle size of 40 nm (product name: TTO55N, manufactured by Ishihara Sangyo Co., Ltd.) and 100 parts of the titanium oxide Surface treatment was carried out by stirring with a supermixer until the temperature reached 160 ° C. Next, 1000 g of a raw material slurry obtained by mixing 250 g of this surface-treated titanium oxide and 750 g of methanol, with zirconia beads having a diameter of about 50 μm (YTZ manufactured by Nikkato Co., Ltd.) as a dispersion medium, a mill volume of about 0.15 L Using an ultra apex mill (UAM-015 type) manufactured by Kotobuki Industries Co., Ltd., a dispersion treatment of 28 minutes was performed in a circulating state with a rotor peripheral speed of 10 m / second and a liquid flow rate of 6 g / second to prepare a titanium oxide dispersion. After stirring and mixing this titanium oxide dispersion and a commercially available copolymerized polyamide resin (product name: CM8000, manufactured by Toray Industries, Inc.) previously dissolved in a mixed solvent of methanol / 1-propanol / toluene, the frequency is 25 kHz and the output is 1200 W. Ultrasonic dispersion treatment with an ultrasonic transmitter is performed for 1 hour, followed by filtration through a PTFE membrane filter (Advantech Mytex LC) having a pore size of 5 μm, and the mass ratio of titanium oxide / copolymerized polyamide is 3 /
1 and the mass ratio of the mixed solvent of methanol / 1-propanol / toluene was 7/1/2, and the coating solution P3 for forming the undercoat layer having a solid content concentration of 18% by mass was obtained.

[Undercoat layer forming coating solution P4]
Undercoat forming coating solution P4 was obtained in the same manner as dispersion P3, except that the surface treating agent was changed to methyldimethoxysilane and the amount of surface treating agent was changed to 3 parts.

[Coating liquid Q1 for forming a charge generation layer]
10 parts of oxytitanium phthalocyanine showing a characteristic peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in a powder X-ray spectrum pattern by CuKα ray, and polyvinyl acetal resin (manufactured by Denki Kagaku Kogyo Co., Ltd.) , Trade name DK31) 5 parts and 1,2-dimethoxyethane 500 parts were mixed and pulverized and dispersed in a sand grind mill to obtain a charge generation layer forming coating solution Q1.

[Coating liquid Q2 for forming a charge generation layer]
In the charge generation layer forming coating solution Q1, in addition to 5 parts of polyvinyl acetal resin (trade name DK31, manufactured by Denki Kagaku Kogyo Co., Ltd.), 2 parts of polyvinyl acetal resin (product name KS1, manufactured by Sekisui Chemical Co., Ltd.) A charge generation layer forming coating solution Q2 was obtained in the same manner as Q1 except that was used.

[Charge transport layer forming coating solution R1]
Polyarylate resin represented by the following structural formula (IV) (viscosity average molecular weight 75,000)
100 parts, 40 parts of a charge transport material represented by the following structural formula (V), 4 parts of dibutylhydroxytoluene, 1 part of tribenzylamine and 1 part of a compound represented by the following structural formula (VI) were added to tetrahydrofuran: toluene = By dissolving and stirring in an 8/2 mixed solvent, a charge transport layer forming coating solution R1 having a solid content concentration of 15% was obtained.

[Coating liquid R2 for forming a charge transport layer]
100 parts of a polyarylate resin represented by the structural formula (IV), 40 parts of a charge transport material represented by the following structural formula (VII), 4 parts of dibutylhydroxytoluene, 1 part of tribenzylamine, the structural formula (VI) 1 part of the compound represented by the following formula was dissolved in a mixed solvent of tetrahydrofuran: toluene = 8/2 and mixed with stirring to obtain a charge transport layer forming coating solution R2 having a solid concentration of 15%.

[Charge transport layer forming coating solution R3]
100 parts of a polyarylate resin represented by the following structural formula (VIII), 40 parts of a charge transport material represented by the above structural formula (VII), 4 parts of dibutylhydroxytoluene, 1 part of tribenzylamine, the above structural formula (VI) 1 part of the compound represented by formula (1) was dissolved in a mixed solvent of tetrahydrofuran: toluene = 8/2 and mixed by stirring to obtain a charge transport layer forming coating solution R3 having a solid concentration of 15%.

[Charge transport layer forming coating solution R4]
100 parts of a polycarbonate resin represented by the following structural formula (VIIII), 40 parts of a charge transport material represented by the structural formula (VII), 4 parts of dibutylhydroxytoluene, 1 part of tribenzylamine, the structural formula (VI) 1 part of the compound represented by the following formula was dissolved in a mixed solvent of tetrahydrofuran: toluene = 8/2 and mixed by stirring to obtain a charge transport layer forming coating solution R4 having a solid concentration of 15%.

<Example 1>
The undercoat layer forming coating solution P1 is dip-coated on an aluminum cylinder having a surface of 30 mmφ and a length of 246 mm, and an undercoat layer is provided so that the dry film thickness is 1.5 μm. It was. The charge generation layer forming coating solution Q1 was dip coated on the undercoat layer, and the charge generation layer was provided so that the dry film thickness was 0.4 g / m ² . A photoreceptor prepared by dip-coating the charge transport layer forming coating solution R1 on the charge generation layer and having a dry film thickness of 18.0 μm is designated as a photoreceptor D1.

<Example 2>
A photoconductor produced in exactly the same manner as the photoconductor D1 except that the charge generation layer forming coating solution Q1 is changed to the coating solution Q2, is designated as photoconductor D2.
<Example 3>
A photoconductor prepared in the same manner as the photoconductor D1 except that the charge transport layer forming coating solution R1 is changed to the coating solution R2, is referred to as a photoconductor D3.

<Example 4>
The undercoat layer forming coating solution P1 was applied to an aluminum plate having a thickness of 1 mm with a wire bar, and an undercoat layer was provided so that the dry film thickness was 1.5 μm. On the undercoat layer, the charge generation layer forming coating solution Q1 was applied with a wire bar, and the charge generation layer was provided so that the dry film thickness was 0.3 g / m ² . A photoconductor prepared by applying the charge transport layer forming coating solution R1 on the charge generation layer with an applicator and having a dry film thickness of 18 μm is defined as a photoconductor S1.

<Example 5>
The undercoat layer forming coating solution P3 was applied to a 1 mm thick aluminum plate with a wire bar, and an undercoat layer was provided so that the dry film thickness was 1.5 μm. The charge generation layer forming coating solution Q2 was applied onto the undercoat layer with a wire bar, and the charge generation layer was provided so that the dry film thickness was 0.3 g / m ² . The photoconductor S2 is a photoconductor prepared by applying the charge transport layer forming coating solution R2 on the charge generation layer with an applicator and having a dry film thickness of 18 μm.

<Comparative Example 1>
The photoconductor D4 was prepared in exactly the same manner as the photoconductor D1, except that the undercoat layer forming coating solution was changed to the dispersion P2.
<Comparative Example 2>
A photoconductor prepared in the same manner as the photoconductor S1 except that the undercoat layer-forming coating solution was changed to the dispersion P2 is referred to as a photoconductor S3.

<Comparative Example 3>
A photoconductor produced in exactly the same manner as the photoconductor S2 except that the undercoat layer forming coating solution was changed to the dispersion P4 is designated as a photoconductor S4.
<Reference Example 1>
A photoreceptor prepared in exactly the same manner as the photoreceptor S2 except that the coating liquid R2 for forming the charge transport layer is changed to the coating liquid R3 is referred to as a photoreceptor S5.

<Reference Example 2>
A photoconductor prepared in the same manner as the photoconductor S5 except that the coating liquid for forming the undercoat layer was changed to the dispersion P4 was designated as photoconductor S6.
<Reference Example 3>
A photoconductor prepared in the same manner as the photoconductor S2 except that the charge transport layer forming coating solution R2 is changed to the dispersion R4 is referred to as a photoconductor S7.

<Reference Example 4>
A photoconductor produced in the same manner as the photoconductor S7 except that the undercoat layer forming coating solution was changed to the dispersion P4 was designated as photoconductor S8.

[Evaluation of electrical characteristics]
Next, an electrophotographic characteristic evaluation apparatus prepared according to the electrophotographic society standard for these electrophotographic photoreceptors D1 to D3 (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405) And mounted on a photoconductor characteristic measuring machine, and according to the following procedure, the electrical characteristics were evaluated by a cycle of charging (negative polarity), exposure, potential measurement, and static elimination. Irradiation energy (half-exposure exposure) when the surface potential is -300 V by charging the photosensitive body so that the initial surface potential is -600 V, and irradiating the light of the halogen lamp with monochromatic light of 740 nm with an interference filter Energy) was measured as sensitivity (E1 / 2) (μJ / cm ² ). Further, the post-exposure surface potential (VL) after 60 ms when the exposure light was irradiated at an intensity of 0.5 μJ / cm ² was measured (−V). Further, the potential holding ratio (DDR) after being charged to −600 V and left for 5 seconds was measured (%).
The electrical property evaluation results are shown in Table-1.

[Adhesion evaluation]
Photoreceptors D1 to D3 were scratched by a 9 × 3 mm square grid with a cutter knife (KO-100YO made HA-100SN) and subjected to a peel test with cellophane tape (TSCT-18 made by Otsuka Shokai). The number of peeled bodies D1 was 2, the number of peeled photoreceptors D2 was 0, and the number of peeled photoreceptors D3 was 3. The number of peeled photoreceptors D4 was 9 (totally peeled). When the photoreceptors S1 to S8 were scratched with 25 mm squares with a razor blade and subjected to a peel test with a cellophane tape (3M), the number of peels from the photoreceptor S1 was 0. However, the number of peeled photoreceptors S3 was 25 (total peeled), and the number of peeled photoreceptors S4 was 13. The number of peeled photoreceptors S3 was 0, but the number of peeled photoreceptors S5 was 23, and the number of peeled photoreceptors S6 was 12. The number of peeled off the photoreceptors S7 and S8 was 0. The evaluation results are shown in Table-2.

  The photoconductors D1 to D3 of the present invention were good in both adhesiveness and electrical characteristics, but the photoconductor D4 of the comparative example had good electrical characteristics but poor adhesiveness. Further, the adhesion of the photoreceptors S1 to S2 of the present invention was good, but the adhesion of the photoreceptors S3 to S4 of the comparative example was bad. In Reference Examples 1 to 4, the adhesion of the photoreceptors S5 to S8 using the polyarylate resin represented by the structural formula (VIII) and the polycarbonate resin structural formula (VIIII) as the binder resin of the charge transport layer was good. . That is, the resin used for the charge transport layer of the reference example has no problem with the adhesiveness in relation to the undercoat layer.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (developing part)
5 Transfer device 6 Cleaning device (cleaning part)
7 Fixing Device 41 Developing Tank 42 Agitator 43 Supply Roller 44 Developing Roller 45 Regulating Member 71 Upper Fixing Member (Pressure Roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (9)

In an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on conductivity, the undercoat layer has surface-treated metal oxide particles having an organic metal compound having the following structural formula (I), a binder resin, An electrophotographic photoreceptor, wherein the photosensitive layer contains a polyarylate resin having the following structural formula (II).

Structural formula (I)
_{^{CH 2 = CR 1 -COO-R}} 2 -M

(R ¹ is a hydrogen atom or an alkyl group, R ² is an alkylene group, M is Si (R ³ ) ₃ , Ti (R ³ ) ₃ , or Al (R ³ ) _2. R ³ is alkyl. Represents a group or an alkoxy group.)

(In the formula (II), Ar ^{1 to} Ar ⁴ each independently represents a phenylene group optionally having an alkyl group, and R ³ and R ⁴ represent a hydrogen atom or an alkyl group. R ³ and R ⁴ represent It may be bonded to form a ring.) 2. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is a laminated photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order. The electrophotographic photosensitive member according to claim 1, wherein R ^{1 in the} structural formula (I) is a methyl group. The organic metal compound having the structural formula (I) is 5 to 30 parts by mass with respect to 100 parts by mass of the metal oxide particles, according to any one of claims 1 to 3. The electrophotographic photosensitive member described. The electrophotographic photosensitive member according to claim 1, wherein the metal oxide particles are n-type semiconductor particles. The electrophotographic photosensitive member according to claim 1, wherein the metal oxide particles are 100 to 400 parts by mass with respect to 100 parts by mass of the binder resin. The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a polyamide resin. An image forming apparatus using the electrophotographic photosensitive member according to claim 1. A cartridge for an image forming apparatus using the electrophotographic photosensitive member according to claim 1.

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