JP2016200757A - Electrophotographic photoreceptor, image forming apparatus, and cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that is excellent in electrical property in the initial stage and after repeated use under various types of use environment from high temperature and high humidity to low temperature and low humidity, and has good adhesiveness and leak resistance, good stability over time of a coating liquid for forming an undercoat layer, and excellent strong transferability; an image forming apparatus; and a cartridge.SOLUTION: There is provided an electrophotographic photoreceptor comprising an undercoat layer and a photosensitive layer on a conductive substrate, where the undercoat layer contains a binder resin, and metal oxide particles that are surface-treated with an organosilicon compound having the structural formula (I) and an organometallic compound having the following structural formula (II).SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photosensitive member having an undercoat layer. More specifically, the present invention relates to electrical characteristics including initial and repetition of low temperature and low humidity to high temperature and high humidity, leakage resistance, adhesion, and formation of an undercoat layer. The present invention relates to an electrophotographic photosensitive member in which the coating solution has good temporal stability and also has good strong transferability.

  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). Among soluble polyamide resins, a copolymerized polyamide resin having a specific diamine component as a constituent component has been proposed as a resin that can realize stable electrical characteristics of a photoreceptor under low temperature and low humidity (see Patent Document 2). As an undercoat layer in which an inorganic material is dispersed in such a polyamide resin, for example, an undercoat layer in which titanium oxide and tin oxide are dispersed in 8-nylon (see Reference 3), in order to improve leakage resistance characteristics An undercoat layer using metal acid compound particles surface-treated with an organometallic compound having an acrylic group is known (see Patent Document 4).

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

When the undercoat layer of the photoreceptor contains metal oxide particles treated with acrylsilane, adhesion and leakage resistance are improved, but there is a problem that strong transferability and stability with time of the coating solution are deteriorated. It was.
The present invention has excellent electrical characteristics, good adhesion and leakage resistance, and stability over time of the coating solution for forming the undercoat layer in various initial and repeated use environments ranging from high temperature and high humidity to low temperature and low humidity. In addition, an object of the present invention is to provide an electrophotographic photosensitive member, an image forming apparatus, and a cartridge which are excellent in strong transferability.

In the electrophotographic photoreceptor having an undercoat layer and a photosensitive layer on a conductive substrate, the present inventors
As a result of intensive investigations on the material used for the undercoat layer, the metal oxide compound particles surface-treated with the organosilicon compound containing the structural formula (I) and the organometallic compound having the structural formula (II), a binder resin, It has been found that a photoconductor using an undercoat layer containing is excellent in electrical characteristics, excellent in adhesion and leak resistance, and also excellent in strong transferability, and has 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 at least an undercoat layer and a photosensitive layer on a conductive substrate, the undercoat layer has an organosilicon compound having the following structural formula (I) and the following structural formula (II). An electrophotographic photoreceptor comprising metal oxide particles surface-treated with an organometallic compound and a binder resin.

(R represents an alkyl group or an aryl group.)

(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.)
<2> The electrophotographic photosensitive member according to <1>, wherein R ^{1 in the} structural formula (II) is a methyl group.
<3> The electrophotographic photosensitive member according to <1> or <2>, wherein the photosensitive layer contains a resin having a universal hardness of 125 N / mm ² or less and an elastic deformation rate of 35% or more.
<4> part The content of the organosilicon compound having the structural formula (I) is 1 to 10 parts by mass with respect to 100 parts by mass of the metal oxide particles, and the organometallic compound having the structural formula (II) The electrophotographic photosensitive member according to any one of <1> to <3>, wherein the electrophotographic photosensitive member is 5 to 20 parts by mass with respect to 100 parts by mass of the metal oxide particles.
<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 member according to any one of <1> to <5>, wherein the metal oxide particles are 50 to 400 parts by mass with respect to 100 parts by mass of the binder resin.
<7> The electrophotographic photosensitive member according to any one of <1> to <6>, wherein the binder resin is a polyamide resin.
<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, the adhesive property between the photosensitive layer and the conductive substrate is good in various usage environments ranging from high temperature and high humidity conditions to low temperature and low humidity conditions, and furthermore, it has electrical characteristics such as charging property and residual potential. It is possible to provide a high-performance electrophotographic photosensitive member excellent in excellent transferability, a high-performance image forming apparatus using the photosensitive member, and a cartridge for an image forming apparatus using the photosensitive member. .

It is the curve which showed the relationship between indentation depth and a load. 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 containing a metal oxide particle surface-treated with an organosilicon compound having the structural formula (I) and an organometallic compound having the structural formula (II) on a conductive support, and a binder resin. A layer is formed.

(R represents an alkyl group or an aryl group.)

(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, a straight chain alkyl group such as methyl group, ethyl group, n-propyl group and n-butyl group, i-propyl group, t-butyl group, ethylhexyl group and the like are branched. Cyclic alkyl groups such as an alkyl group and a cyclohexyl group. From the viewpoint of leak resistance, an alkyl group having 3 or less carbon atoms is preferable, and a methyl group is more preferable. Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group. From the viewpoint of leak resistance, a phenyl group is preferred.

Examples of the organosilicon compound having the structural formula (I) group include methyl hydrogen polysiloxane, methyldimethoxysilane, phenyldimethoxysilane, and methyldiethoxysilane. Of these, methyldimethoxysilane is preferred from the viewpoint of coating solution stability.
In the structural formula (II), 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 (II) is preferably a silane coupling agent. Among the organometallic compounds, 3-methacryloxypropyltrimethoxysilane or 3-methacryloxypropyltriethoxysilane is particularly preferable from the viewpoint 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, particularly preferably 40 nm or less from the viewpoint of dispersion stability in the coating solution. Usually 1n
m or more, preferably 10 nm or more, particularly preferably 20 nm or more from the viewpoint of suppressing aggregation. 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 size of 100 nm and 30 nm may be used.

  Treated with an organosilicon compound having the structural formula (I) of the present invention (hereinafter sometimes referred to as surface treating agent 1) and an organometallic compound having the structural formula (II) (hereinafter sometimes referred to as surface treating agent 2). The surface treatment agent 1 and the surface treatment agent 2 are simultaneously surface-treated with the metal oxide particles. The surface treatment agent 1 is surface treated with the surface treatment agent 2 after the surface treatment agent 1 is surface-treated with the metal oxide particles. The surface treatment agent 2 can be prepared by subjecting the metal oxide particles to a surface treatment with the surface treatment agent 1, but from the viewpoint of adhesiveness, after the surface treatment with the surface treatment agent 1 is performed. Surface treatment with the surface treatment agent 2 is preferred.

  The surface treatment can be performed by a dry method or a wet method. That is, in the dry method, the surface treatment agent 1 or 2 can be coated with the metal oxide particles by mixing with the metal oxide particles, and can be manufactured by a heat treatment if 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.

The organosilicon compound having the structural formula (I) is preferably 1 part by mass or more, more preferably from the viewpoint of the stability of the coating solution, leakage resistance and strong transferability with respect to the metal oxide particles used. From the viewpoint of electrical characteristics, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.
The organometallic compound having the structural formula (II) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more from the viewpoint of adhesion to the metal oxide particles used, and the stability and strength of the coating solution From a transferable viewpoint, Preferably it is 30 mass parts or less, More preferably, it is 20 mass parts or less.

Content ratio of the organosilicon compound having the structural formula (I) and the organometallic compound having the structural formula (II) to the metal oxide particles (organosilicon compound having the structural formula (I) / organic having the structural formula (II) The metal compound) is preferably 1/10 or more and 2/10 or more from the viewpoint of leakage resistance. Moreover, it is 10/1 or less normally, and 10/5 or less is preferable from an adhesive viewpoint.
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 from the electrical characteristics aspect,
The amount 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. Moreover, from a viewpoint of stability of a liquid and applicability | paintability, it is 800 mass parts or less normally, and 400 mass parts or less are preferable. The undercoat layer is mainly composed of metal oxide particles coated with an organosilicon compound having the structural formula (I) and an organometallic compound having the structural formula (II), and a binder resin. Metal oxide particles surface-treated only with an organosilicon compound having the formula (I), metal oxide particles surface-treated only with an organometallic compound having the structural formula (II), and other surface-treated metal acid compound particles ( Fluorine silane-treated titanium oxide, phenylsilane-treated titanium oxide, etc.) may be added. Moreover, you may add metal compound particle | grains without surface treatment, antioxidant, an additive, a electrically conductive agent, etc.

The thickness of the undercoat layer is usually 0.1 μm or more, and preferably 0.5 μm or more, more preferably 1 μm or more from the viewpoint of the effect on local charging failure. Further, it is usually used at a thickness of 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, from the viewpoint of residual potential or adhesive strength between the conductive substrate and the photosensitive layer. 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. Usually, it is 1 × 10 ¹⁴ Ω · cm or less, preferably 1 × 10 ¹³ Ω · cm or less.

  In order to obtain an undercoating coating solution containing metal oxide particles surface-treated with an organosilicon compound having the structural formula (I) and an organometallic compound having the structural formula (II) and a binder resin, a planetary mill is used. A slurry of surface-treated metal oxide particles treated with a grinding or dispersion treatment device such as a ball mill, sand mill, bead mill, paint shaker, attritor, or ultrasonic wave, and a binder resin solution in which a binder resin is previously dissolved in an appropriate solvent. Mixing and stirring may be performed. It can also be obtained by adding a binder resin to the dispersion slurry of surface-treated metal oxide particles and dissolving it. Moreover, it can also disperse | distribute using a small diameter bead as described in patent 4985093. Furthermore, metal oxide particles can be added to the binder resin solution, and pulverization or dispersion treatment can be performed with the dispersing device.

[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. There is a functional separation type (laminated type) consisting of two layers of a charge transport layer in which a transport material is dispersed in a binder resin. In the negative charge system, the charge generation layer and the charge transport layer are formed from the conductive support side. It is preferable that it is a sequential lamination type photosensitive layer provided by laminating in order. In the positive charging system, a single layer type is preferable. 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 resin is particularly preferable, and polyvinyl butyral resin is preferable as the polyvinyl acetal resin. 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 Transport 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.
The binder resin is preferably a resin having a universal hardness of 125 N / mm ² or less and an elastic deformation rate of 35% or more from the viewpoint of wear resistance. The universal hardness is more preferably 120 N / mm ² or less from the viewpoint of wear resistance. Moreover, it is usually 80 N / mm ² or more, and from the viewpoint of scratch resistance, 100 N / mm ² or more is preferable. The elastic deformation rate is preferably 40% or more from the viewpoint of wear resistance and cleaning properties. Moreover, it is 90% or less normally, and 80% or less is preferable from a viewpoint of adhesiveness and solubility.

  The universal hardness and elastic deformation rate are values measured using a micro hardness meter (Fischer: FISCHERSCOPE H100C) in an environment of a temperature of 25 ° C. and a relative humidity of 50%. For the measurement, a Vickers square pyramid diamond indenter having a facing angle of 136 ° is used. The measurement conditions are set as follows, the load applied to the indenter and the indentation depth under the load are continuously read, and profiles as shown in FIG. 1 plotted on the Y axis and the X axis are obtained.

Measurement conditions Maximum load 5mN
Load time 10s
Unloading time 10s
The universal hardness is a value when pushed in with a maximum load of 5 mN, and is a value defined by the following equation from the displacement amount at that time.

Universal hardness (N / mm ² ) = maximum load (N) / surface area of Vickers indenter under maximum load (mm ² )
Elastic deformation rate (%) = (We / Wt) × 100
In the above formula, Wt represents the total work (nJ), and is represented by the area surrounded by A-B-D-A in FIG.

  Examples of the binder resin include polymers and copolymers of vinyl compounds such as butadiene resin, styrene resin, vinyl acetate resin, vinyl chloride resin, acrylic ester resin, methacrylic ester resin, vinyl alcohol resin, ethyl vinyl ether, and polyvinyl butyral. Resin, polyvinyl formal resin, partially modified polyvinyl acetal, polycarbonate resin, polyarylate resin, polyester resin, polyamide resin, polyurethane resin, cellulose ester resin, phenoxy resin, silicon resin, silicon-alkyd resin, poly-N-vinylcarbazole resin, etc. However, polyarylate resin or polycarbonate resin is preferable in terms of electrical characteristics and wear resistance. Among these, polyarylate resin or polycarbonate resin having the following units is particularly preferable.

  Examples of the charge transport material include aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, electron transport materials such as quinone compounds such as diphenoquinone, carbazole derivatives, indole derivatives, Heterocyclic compounds such as imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and combinations of these compounds Or a hole transporting substance such as a polymer having a group composed of these compounds in the main chain or side chain. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, and enamine derivatives are preferable from the viewpoint of electrical characteristics, and tertiary aromatic amine derivatives are particularly preferable. 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.

  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 long life and sensitivity, and is usually 40 μm or less, preferably 25 μm or less from the viewpoint of high resolution and productivity.
[Single-layer type photosensitive layer]
The single-layer type photosensitive layer contains a charge generation material, a charge transport material, and a binder resin. Furthermore, you may contain another component as needed. It can be obtained by dissolving or dispersing a charge generating substance, a charge transporting substance and the like and a binder resin in a solvent to prepare a coating solution, and coating and drying on the undercoat layer.

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.

[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. 2, 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 the examples, “parts” means “parts by mass” unless otherwise specified.

<Manufacture of surface-treated titania>
[Surface treatment titania A]
A rutile type white titanium oxide having an average primary particle size of 40 nm (product name: TTO55N, manufactured by Ishihara Sangyo Co., Ltd.) and 100 parts of titanium oxide, 3 parts of methyldimethoxysilane, and a temperature in the mixer of 160 parts by shearing force. Surface treatment was performed by stirring with a supermixer until reaching ° C. to obtain surface-treated titania A.

[Surface treatment titania B]
Mixer of rutile type white titanium oxide (product name: TTO55N, manufactured by Ishihara Sangyo Co., Ltd., product name: TTO55N) having an average primary particle size of 40 nm and 15 parts of 3-methacryloxypropyltrimethoxysilane by shearing force. Surface treatment was performed by stirring with a supermixer until the inside temperature reached 160 ° C. to obtain surface-treated titania B.

[Surface treatment titania C]
Rutile-type white titanium oxide having an average primary particle size of 40 nm (product name: TTO55N, manufactured by Ishihara Sangyo Co., Ltd.) and 100 parts of titanium oxide, 10 parts of 3-methacryloxypropyltrimethoxysilane, 300 parts of methanol, After carrying out bead mill dispersion with 5 mmφ zirconia beads, after evaporating methanol under reduced pressure, surface treatment was performed by baking at 130 ° C. for 2 hours, and then dry pulverization to obtain surface-treated titania C. Obtained.

[Surface treatment titania D]
To 100 parts of surface-treated titania A, 10 parts of 3-methacryloxypropyltrimethoxysilane and 300 parts of methanol were subjected to bead mill dispersion with 0.5 mmφ zirconia beads, and then the methanol was evaporated under reduced pressure. Surface treatment was performed by baking at 130 ° C. for 2 hours, and then surface-treated titania D was obtained by dry pulverization.

<Manufacture of dispersion for undercoat layer coating formation>
[Coating liquid P1 for forming the undercoat layer]
Raw material slurry 100 obtained by mixing 25 g of surface-treated titania A and 75 g of methanol
g was ball mill dispersed with 5 mmφ alumina beads 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. The ultrasonic dispersion treatment with an ultrasonic transmitter is performed for 1 hour, the mass ratio of titanium oxide / copolymerized polyamide is 2/1, and the mass ratio of the mixed solvent of methanol / 1-propanol / toluene is 7/1/2. Thus, an undercoat layer forming coating solution P1 having a solid content concentration of 15.75% was obtained.

[Undercoat layer forming coating solution P2]
Undercoat forming coating liquid P2 was obtained in the same manner as dispersion P1, except that surface-treated titania A was changed to surface-treated titania B.
[Undercoat layer forming coating solution P3]
Except for changing the surface-treated titania A to surface-treated titania C, a coating solution P3 for undercoating was obtained in the same manner as the dispersion P1.

[Undercoat layer forming coating solution P4]
Undercoat forming liquid P4 was obtained in the same manner as dispersion P1, except that surface-treated titania A was changed to surface-treated titania D.
[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.) , 5 parts of a product name DK31) and 2 parts of polyvinyl acetal resin (manufactured by Sekisui Chemical Co., Ltd., trade name KS1) are mixed with 500 parts of 1,2-dimethoxyethane, and pulverized and dispersed by a sand grind mill. Then, a coating solution Q1 for forming a charge generation layer was obtained.

[Coating liquid Q2 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) was mixed with 500 parts of 1,2-dimethoxyethane, and pulverized and dispersed in a sand grind mill to obtain a charge generation layer forming coating solution Q2.

[Charge transport layer forming coating solution R1]
Polyarylate resin (viscosity average molecular weight 70,000) represented by the following structural formula (A) 1
00 parts, 40 parts of a charge transport material represented by the following structural formula (V), 4 parts of dibutylhydroxytoluene, 1 part of tribenzylamine, 1 part of a compound represented by the following structural formula (VI) 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]
The charge transport layer is the same as the charge transport layer forming coating solution R1 except that the charge transport material represented by the structural formula (V) is changed to a charge transport material represented by the following structural formula (VII). A forming coating solution R2 was obtained.

[Binder resin liquid T1]
Polyarylate resin represented by the structural formula (A) (viscosity average molecular weight 37,000) 1
00 parts, 0.07 parts of silicone oil (trade name KF-96, manufactured by Shin-Etsu Silicone Co., Ltd.) is stirred and mixed in a mixed solvent of tetrahydrofuran: toluene = 8: 2, so that the solid content concentration is 12.0% by mass. A resin liquid T1 was obtained.

<Example 1>
The undercoat layer forming coating solution P4 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 charge transport layer forming coating solution R1 is applied onto the charge generation layer with an applicator, dried at 125 ° C. for 20 minutes, and a photoreceptor prepared so that the dry film thickness is 18 μm is designated as photoreceptor S1.

<Comparative Example 1>
A photoreceptor prepared in the same manner as the photoreceptor S1 except that the undercoat layer forming coating liquid P4 is changed to the undercoat layer forming coating liquid P1 is referred to as a photoreceptor S2.
<Comparative example 2>
A photoreceptor prepared in the same manner as the photoreceptor S1 except that the undercoat layer forming coating liquid P4 is changed to the undercoat layer forming coating liquid P2 is referred to as a photoreceptor S3.

<Comparative Example 3>
A photoconductor prepared in the same manner as the photoconductor S1 except that the undercoat layer forming coating solution P4 is changed to the undercoat layer forming coating solution P3 is referred to as a photoconductor S4.
<Example 2>
The undercoat layer forming coating solution P4 was applied onto polyethylene terephthalate on which aluminum was vapor-deposited 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 . A charge transport layer forming coating solution R2 is applied onto the charge generation layer with an applicator, dried at 125 ° C. for 20 minutes, and a photoreceptor prepared to have a dry film thickness of 17.5 μm is designated as photoreceptor T1. .

<Comparative example 4>
A photoconductor produced in the same manner as the photoconductor T1 except that the undercoat layer forming coating solution P4 is changed to the undercoat layer forming coating solution P1 is referred to as a photoconductor T2.
<Comparative Example 5>
A photoreceptor prepared in the same manner as the photoreceptor T1 except that the undercoat layer forming coating solution P4 is changed to the undercoat layer forming coating solution P2 is referred to as a photoreceptor T3.

<Comparative Example 6>
A photoreceptor prepared in the same manner as the photoreceptor T1 except that the undercoat layer forming coating liquid P4 is changed to the undercoat layer forming coating liquid P3 is referred to as a photoreceptor T4.
[Sample B1 for universal hardness and elastic deformation measurement]
The binder resin liquid T1 was applied to a glass plate having a thickness of 4 mm with an applicator, dried at 125 ° C. for 20 minutes, and a resin layer was provided so that the dry film thickness was 15 μm. This universal hardness measurement and elastic deformation rate determination sample is designated as B1.

[Adhesion evaluation]
The photoreceptors S1 to S4 were scratched with 25 squares of 2 mm square with a razor blade, and a peel test was performed with a cellophane tape (3M). Table 1 shows the number of peels of each photoconductor.

[Evaluation of electrical characteristics]
Next, these photoconductors T1, T2, T3, and T4 are wound around an 80 mmφ aluminum cylinder, and an electrophotographic characteristic evaluation apparatus manufactured in accordance with the standard of the electrophotographic society (basic and applied electrophotographic techniques, edited by the Electrophotographic Society, Corona, (Pages 404 to 405), and mounted on a photoreceptor characteristic measuring machine, and the electrical characteristics were evaluated according to the cycle of charging (minus polarity), exposure, potential measurement, and static elimination according to the following procedure. Irradiation energy (half-exposure exposure) when the surface potential becomes -350 V by charging the photosensitive member so that the initial surface potential is -700 V and irradiating the light of the halogen lamp with a monochromatic light of 780 nm with an interference filter. Energy) was measured as sensitivity (E1 / 2) (μJ / cm ² ). Further, the exposure light is 0.9 μJ / c.
The post-exposure surface potential (VL) after 60 ms when irradiated at an intensity of m ² was measured (−V). Further, the potential holding ratio (DDR) after being charged to −700 V and left for 5 seconds was measured (%).
The electrical property evaluation results are shown in Table-2.

[Evaluation of strong transferability]
Wrap photoconductors T1, T2, T3, and T4 around a 30mmφ aluminum cylinder,
It is installed in the modified machine of the electrophotographic characteristic evaluation apparatus used in the evaluation of electrical characteristics, and charging (minus polarity), potential measurement, + charging (plus polarity), and static elimination cycles are performed to determine the first charging potential. The difference in charging potential for the second time after one cycle was defined as ΔV0. The results are shown in Table-2. For negative charging, a scorotron charger was used, and the first charging was set to −700V. For the positive charging, a corotron charger was used, and the potential of the photosensitive member T1 was set to be +1 kV.

  A photoconductor having a large ΔV0 in the above model test tends to generate memory. The reason is that in the case of a photoconductor having a large ΔV0, since the toner is not carried on the unexposed portion, the effect of transfer is directly affected, so that the V0 drop is large. On the other hand, since the toner is carried on the exposed portion, it is not easily affected by the transfer, and the decrease in V0 is small. That is, a photoconductor having a large ΔV0 in the model test has a large difference between V0 between the exposed portion and the unexposed portion, and a memory is easily generated. On the other hand, a photoconductor having a small ΔV0 in the model test is not easily affected by the transfer even if the toner is not carried, so the difference between V0 between the exposed portion and the unexposed portion is small, and memory is hardly generated.

[Universal hardness and elastic deformation measurement]
Sample B1 for measuring universal hardness and elastic deformation rate was measured in a microhardness meter (FischerSCOPE HM200, manufactured by Fischer) in an environment of a temperature of 25 ° C. and a relative humidity of 50%.
0) was measured under the following measurement conditions. Table 3 shows the universal hardness and elastic deformation rate of B1.

(Universal hardness and elastic deformation rate measurement conditions)
Indenter: Vickers square pyramid diamond indenter with a face angle of 136 ° Maximum indentation load: 5 mN
Time required for loading: 10 seconds Time required for unloading: 10 seconds The universal hardness is obtained from the following equation.
Universal hardness (N / mm2) = Maximum indentation load / Indentation area at maximum indentation load

  When the undercoat layer contained metal oxide particles that were surface-treated only with the silane treating agent (photosensitive members S2 and T2), the adhesion was poor. When the undercoat layer contained metal oxide particles surface-treated only with the structural formula (I) (photosensitive members S3, S4, T3, T4), the strong transferability was poor. Electrical properties and strong transferability were good only when the undercoat layer contained a silane treating agent and metal oxide particles surface-treated with the structural formula (I) (photosensitive member S1 and photosensitive member T1). In particular, in terms of adhesiveness, when each was processed alone, peeling occurred, but there was no peeling only in the case of the photoreceptor S1.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (development unit)
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 a conductive substrate, the undercoat layer has a surface made of an organosilicon compound having the structural formula (I) and an organometallic compound having the following structural formula (II). An electrophotographic photoreceptor comprising treated metal oxide particles and a binder resin.

(R represents an alkyl group or an aryl group.)

(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.) The electrophotographic photoreceptor according to claim 1, wherein R ^{1 in the} structural formula (II) is a methyl group. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains a binder resin, the binder resin has a universal hardness of 125 N / mm ² or less and an elastic deformation rate of 35% or more. body. The content of the organosilicon compound having the structural formula (I) is 1 to 10 parts by mass with respect to 100 parts by mass of the metal oxide particles, and the content of the organometallic compound having the structural formula (II) is a metal. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the amount is 5 to 20 parts by mass with respect to 100 parts by mass of the oxide particles. The electrophotographic photosensitive member according to claim 1, wherein the metal oxide particles are n-type semiconductor particles. 6. The electron according to claim 1, wherein the content of the metal oxide particles is 50 to 400 parts by mass with respect to 100 parts by mass of the binder resin in the undercoat layer. Photoconductor. The electrophotographic photosensitive member according to claim 1, wherein the binder resin of the undercoat layer 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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