JP2015141235A - Electrophotographic cartridge, electrophotographic photoreceptor, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic cartridge configured to prevent cracks as well as filming, even when a large amount of silica particles are added to obtain filming effect, and an electrophotographic photoreceptor, and an image forming apparatus.SOLUTION: An electrophotographic cartridge includes an electrophotographic photoreceptor, charging means, image exposure means which performs image exposure to form an electrostatic latent image, and developing means which develops the electrostatic latent image with toner. The charging means is contact roller charging. The electrophotographic photoreceptor includes a charge generating layer and a charge transport layer formed in this order on a conductive substrate. The charge transport layer is a single layer and an outermost surface layer, and includes a charge transport material, a binder resin having a repeated structure unit with a molecular weight of 210-290, and silica particles having an average primary particle size of 0.1-1.5 μm. The content of the silica particles in the charge transport layer is 3-20wt%.

Description

  The present invention relates to an electrophotographic cartridge, an electrophotographic photosensitive member, and an image forming apparatus used for a copying machine, a printer, and the like.

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 laminated type photoconductor in which a charge generation function and a charge transport function are separated has become the mainstream. Currently, these photoreceptors are widely used in the field of image forming apparatuses such as copying machines and laser printers.

  In general, in order to form an image by electrophotography, a toner image is formed by charging, image exposure and development on the surface of a photoreceptor, and the toner image is transferred and fixed on a transfer material to obtain an image. This photoreceptor is used repeatedly over a long period of time after residual toner is cleaned. If the cleaning is not performed well, the residual toner adheres to the photoconductor, causing an image defect (hereinafter referred to as filming).

In recent years, low-temperature fixing toners have been used for the purpose of energy saving in image forming apparatuses, and toners with large sphericity and small particle diameter have been used from the viewpoint of improving image quality, and filming is more likely to occur. It has become. It has been a big challenge to suppress filming images while maintaining good electrical characteristics in each environment.
As a countermeasure against filming, a surface protective layer or a plurality of charge transport layers are provided. For example, as a surface protective layer, a technique (Patent Document 1) containing microcapsules containing lubricating oil in the surface protective layer, a trimethylolpropane acrylate crosslinked product, a cured organosilica film, and heat or light There exists a technique (patent document 2) containing a crosslinked type crosslinked body.

  On the other hand, as a technique for containing fine particles in the surface protective layer, a technique for containing fine particles such as titanium oxide and tin oxide in the surface protective layer and setting the absorbance per 1 μm of the film thickness of the surface protective layer to a specific value (patent) Document 3), a technique (Patent Document 4) containing a radical polymerizable monomer, a crosslinkable resin and a filler in the surface protective layer, and a technique (Patent Documents 5 to 8) containing silica particles in the surface layer. Among these technologies, when a protective layer is not provided and the outermost surface layer becomes a charge transport layer, the dispersion stability of the coating solution for forming the surface layer is good, the productivity is good, and the room temperature and humidity are high. There is a need for a photoreceptor that has good electrical characteristics including high humidity repeatability and is effective in suppressing filming.

JP 2006-99035 A JP 2008-26689 A JP 2003-140373 A JP 2012-98639 A Japanese Patent No. 3844258 Japanese Patent No. 3859086 JP 2002-182409 A JP 2012-103619 A

  Among the techniques described above, the technique of containing silica particles in the surface layer is simple, and filming can be reduced. However, due to the dispersion of silica particles, when the cartridge on which the photoconductor is mounted is stored for a long time, a crack-like defect (hereinafter referred to as a crack) is formed on the photoconductor at the contact position with the roller member. It was found that is likely to occur. In particular, in the case of the contact charging method, the tendency is remarkable when a large amount of silica particles is added.

  An object of the present invention is to obtain an electrophotographic cartridge, an electrophotographic photosensitive member, and an image forming apparatus in which cracking does not occur while suppressing filming even when a large amount of silica particles is added to obtain a filming effect. is there.

The object of the present invention is achieved by adopting any one of the following configurations <1> to <13>. <1> An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an image exposing unit for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image In an electrophotographic cartridge having developing means for developing with toner,
The charging means is contact roller charging;
The electrophotographic photoreceptor has a charge generation layer and a charge transport layer in this order on a conductive substrate. The charge transport layer is a single layer and an outermost surface layer. The charge transport material has a molecular weight of 210 or more and 290. A binder resin having a repeating structural unit, and silica particles having an average primary particle size of 0.1 μm or more and 1.5 μm or less,
The electrophotographic cartridge according to claim 1, wherein the content of the silica particles is 3 to 20 wt% of the entire charge transport layer.
<2> The electrophotographic cartridge according to <1>, wherein the silica particles have an average primary particle size of 0.3 μm or more and 0.9 μm or less.
<3> The electrophotographic cartridge according to <1> or <2>, wherein the silica particles are surface-treated with a reactive organosilicon compound.
<4> The electrophotographic cartridge according to any one of <1> to <3>, wherein the sphericity of the silica particles is 0.95 to 1.0.
<5> The electrophotographic cartridge according to any one of <1> to <4>, wherein the density of the silica particles is 1.5 g / cm ³ or more and 3.0 g / cm ³ .
<6> The content of the silica particles is 5 to 15 wt% of the entire charge transport layer, <1> to <5
> The electrophotographic cartridge according to any one of the above.
<7> The electrophotographic cartridge according to any one of <1> to <6>, wherein the binder resin has a repeating structure represented by the following formula (1).

(In formula (1), R ¹ and R ² each independently represent hydrogen or a methyl group.)
<8> The charge transport material has a solubility in toluene of 10% or more, <
The electrophotographic cartridge according to any one of 1> to <7>.
<9> The electrophotographic cartridge according to any one of <1> to <8>, wherein the charging roller is disposed so as not to directly contact the charge transport layer.
<10> An image forming apparatus using the electrophotographic cartridge according to any one of <1> to <8>.
<11> In an electrophotographic photosensitive member charged by a charging roller used in an image forming apparatus,
A conductive support;
A charge generation layer;
A charge transport layer of a single layer and an outermost surface layer, having a contact portion with the charging roller, a charge transport material, a binder resin having a repeating structural unit having a molecular weight of 210 to 290, and an average primary particle size Containing 0.1 to 1.5 μm silica particles, and the content of the silica particles is 3 to 20 wt% of the entire charge transporting layer;
An electrophotographic photoreceptor, wherein a charge generation layer and a charge transport layer are laminated in this order on the conductive support.
<12> The electrophotographic photosensitive member according to <11>, wherein the silica particles have a sphericity of 0.95 to 1.0.
<13> The electrophotographic photosensitive member according to <11> or <12>, wherein the density of the silica particles is 1.5 g / cm ³ or more and 3.0 g / cm ³ or less.

  According to the present invention, the productivity is good, the stability of the coating liquid for forming the charge transport layer is good, and even when it is a contact charging method, it has excellent electrical characteristics including repeated normal temperature and high humidity, high temperature and high humidity, An electrophotographic cartridge capable of suppressing filming and cracks, an electrophotographic photosensitive member, and an image forming apparatus are obtained.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. It is a chart which shows the CuK (alpha) characteristic X-ray-diffraction peak of phthalocyanine used in an Example. It is a chart which shows the CuK (alpha) characteristic X-ray-diffraction peak of phthalocyanine used in an Example.

  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>
The charge generation layer is formed directly on the conductive support or on the conductive layer, undercoat layer and the like. A single charge transport layer is formed on the charge generation layer, and the charge transport layer becomes the outermost surface 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 in 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. Furthermore, 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 the drawing tube as it is without performing the cutting process.

<Underlayer>
In the present invention, the undercoat layer is not essential, but when an undercoat layer is provided, any undercoat layer can be provided. As the undercoat layer, a binder alone can be used, but it is preferable in terms of electrical characteristics and the like to contain an inorganic filler such as metal oxide particles.
As the metal oxide particles, those having high dispersion stability of the coating liquid are preferable, and specific examples include silica, alumina, titanium oxide, barium titanate, zinc oxide, lead oxide, and indium oxide. Among these, metal oxide particles exhibiting n-type semiconductor characteristics are preferable, titanium oxide, zinc oxide, and tin oxide are more preferable, and titanium oxide is most preferable.

  As for the particle size of the metal compound particles, those having an average particle size of usually 100 nm or less are preferable, and 10 to 60 nm is particularly preferable, for the reason of dispersion stability in the coating solution. The particle size of the particles used in the coating solution may be uniform or a composite system having different particle sizes. In the case of a composite system having different particle sizes, those having a maximum particle size peak near 150 nm and a particle size distribution with a minimum particle size of about 30 nm to about 500 nm are preferable. And 0.03 μm may be mixed and used.

  The metal oxide particles are preferably surface-treated with an organometallic compound or the like. The surface treatment can be produced by a dry method or a wet method. That is, in the dry method, it can be produced by a method in which a surface treatment agent is mixed with metal oxide particles to coat the metal oxide particles and, if necessary, heat treatment is performed. 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 surface treating agent is preferably a reactive organometallic compound. For example, methyl hydrogen polysiloxane, a silane treating agent having the following structure, and among them, methyldimethoxysilane is particularly preferable. A silane coupling agent having an acrylic group is also preferable, and 3-acryloxypropylmethoxysilane is particularly preferable.

(M is SiR ³ or the like, R is a hydrogen atom or an alkyl group, R ¹ and R ² are an alkyl group, and R ³ is an alkyl group or an alkoxy group)
As the binder resin contained in 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 in 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. Among them, in particular, the following general formula (2) A copolymerized polyamide resin having the diamine component shown as a constituent material is preferred.

In formula (2), 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 and the binder resin can be arbitrarily selected, but is 0.5 to 8 parts by mass with respect to 1 part by mass of the binder resin in terms of liquid stability, coatability, and electrical characteristics. The range is preferable, and the range of 2 parts by mass to 5 parts by mass is more preferable.

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 preferably 0.1 to 20 μm, more preferably 2 to 10 μm, still more preferably 3 to 6 μm.
In order to obtain an undercoating coating solution containing metal oxide particles and a binder resin, a metal oxide treated with a pulverization or dispersion treatment device such as a planetary mill, ball mill, sand mill, bead mill, paint shaker, attritor, or ultrasonic wave. The particle slurry may be mixed with a binder resin or a solution obtained by dissolving the binder resin in an appropriate solvent, and dissolved and stirred. Conversely, metal oxide particles may be added to the binder resin solution, and pulverization or dispersion treatment may be performed with the above-described dispersing apparatus.

<Charge generation layer>
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 an organic pigment is used as the charge generating material, a phthalocyanine pigment or an azo pigment is particularly preferable. The phthalocyanine pigment provides a photosensitive material with high sensitivity to a laser beam having a relatively long wavelength, and the azo pigment has a sufficient sensitivity to white light and a laser beam having a relatively short wavelength. , Each is excellent.

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 A hydroxygallium phthalocyanine, G-type μ-oxo-gallium, having a clear peak at 28.1 ° and a half width W of 25.9 ° of 1 ° ≦ W ≦ 0.4 ° A phthalocyanine dimer and the like are particularly preferable.

  As the phthalocyanine compound, a single compound may be used, or several mixed or mixed crystals may be used. 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 And organic photoconductive polymers such as perylene. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.

Specifically, the charge generation layer is prepared by, for example, preparing a coating solution by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent, and providing this on a conductive support (providing an undercoat layer). In some cases, it is formed by coating on an undercoat layer.
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 weight or less. 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.

  As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or a bead mill dispersion can be used. At this time, 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.

<Charge transport layer>
A single charge transport layer is formed on the charge generation layer, and the charge transport layer becomes the outermost surface layer. The charge transport layer contains a binder resin and a charge transport material, contains silica particles of 0.1 μm or more and 1.5 μm or less, and the content of silica particles is 3 to 20 wt% of the entire charge transport layer.
It is. You may contain another component as needed.
Specifically, such a charge transport layer is obtained by, for example, preparing a coating solution by dissolving or dispersing a charge transport material and the like, a binder resin, and silica particles in a solvent, and coating and drying on the charge generation layer. be able to.

  From the viewpoint of filming resistance, the average primary particle diameter of the silica particles is 0.1 μm or more, preferably 0.2 μm or more, more preferably 0.3 μm or more, and 0.4 μm or more. Particularly preferred. From the viewpoint of coating solution stability, it is 1.5 μm or less, more preferably 0.9 μm or less, and even more preferably 0.8 μm or less. When the average primary particle diameter of the silica particles is smaller than 0.1 μm, the filming suppressing effect is small. When it is larger than 1.5 μm, the stability of the coating solution is deteriorated.

  From the viewpoint of filming resistance, the lower limit of the content of silica particles is 3 wt% or more of the entire charge transport layer, and preferably 5 wt% or more. From the viewpoint of electrical characteristics, the upper limit is preferably 20 wt% or less and 15 wt% or less, and particularly preferably 10 wt% or less of the entire charge transport layer. When the content of silica particles is less than 3 wt%, the effect of suppressing filming is small. When the amount is more than 20 wt%, the aggregation of the silica particles in the charge transport layer film becomes severe, so that the effect of suppressing filming is diminished and the dispersion stability of the coating solution is deteriorated.

The sphericity of the silica particles is usually 0.95 or more, preferably 0.96 or more, more preferably 0.98 or more, from the viewpoint of crack resistance. The greater the sphericity, the smaller the surface area of the silica and the fewer the interfaces that cause cracks, making cracks less likely to occur. The upper limit is 1.0 or less.
From the viewpoint of crack resistance, the lower limit of the density of the silica particles is usually 1.5 g / cm ³ or more, preferably 1.8 g / cm ³ or more, more preferably 2.0 g / cm ³ or more. From the viewpoint of crack resistance, the upper limit is usually 3.0 g / cm ³ or less, preferably 2.8 g / cm ³ or less, more preferably 2.5 g / cm ³ or less.

  The silica particles are preferably surface-treated with a reactive organosilicon compound. The surface treatment can be produced by a dry method and a wet method. In the dry method, the surface treatment agent can be mixed with the metal oxide particles so that the metal oxide particles are coated, 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 be manufactured by performing heat treatment.

Examples of reactive organosilicon compounds include silane coupling agents, silane treatment agents, and siloxane compounds, with silane treatment agents being preferred. Among the silane treatment agents, silane treatment agents having an alkyl group having 1 to 3 carbon atoms are preferable. Such silane treating agents include hexamethyldisilazane, trimethylmethoxysilane, trimethylethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, dimethyldimethoxysilane, dimethylethoxysilane, methyldimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane. Etc.

  The charge transport material is not particularly limited as long as it is a known material. For example, aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, diphenoquinone, etc. Electron withdrawing materials such as quinone compounds, 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, Examples thereof include butadiene derivatives and those obtained by bonding a plurality of these compounds, or electron donating materials such as polymers having a group consisting of these compounds in the main chain or side chain. Among these, aromatic amine derivatives, stilbene derivatives, hydrazone derivatives, and those obtained by bonding a plurality of these compounds are preferable.

Among these, the solubility in toluene is 10% or more, preferably 15% or more, more preferably 20% or more, and particularly preferably 25% or more. As the solubility of toluene is higher, a photoreceptor that is less susceptible to cracking can be obtained.
Examples of the binder resin used for the charge transport layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyarylate, polyester, polyester carbonate, polysulfone, polyimide, phenoxy, Examples thereof include epoxies and silicone resins, and these partially crosslinked cured products can also be used. Of the binder resins, polycarbonate resins and polyarylate resins are particularly preferable. These resins may be used alone or in combination.

  In the present invention, a binder resin having units having a molecular weight of 210 or more and 290 or less is used. From the viewpoint of preventing cracks, it is preferably 280 or less, more preferably 260 or less, and 240 or less. From the viewpoint of preventing cracking, the lower limit of the unit amount having a molecular weight of 210 or more and 290 or less is 10 mol% or more, preferably 15 mol% or more, more preferably 20 mol% or more. The upper limit is 100 mol% or less, preferably 80 mol% or less, from the viewpoint of applicability. The reason is not clear, but it is thought that cracks are less likely to occur because the smaller molecular weight makes it easier to form a dense structure.

From the viewpoint of cracks and wear resistance, a binder resin having a structural unit represented by the following formula (1) or (2) is preferable.
From the viewpoint of electrical characteristics, the binder resin preferably has a repeating structure represented by the following formula (1).

(In formula (1), R ¹ and R ² each independently represent hydrogen or a methyl group.)
The binder resin preferably has a repeating structure represented by the following formula (2) from the viewpoint of wear resistance.

(In formula (2), X represents a single bond or a divalent linking group having 9 or less elements.)
Examples of the linking group having 9 or less elements include an oxygen atom, a sulfur atom, and -CRaRb-. As Ra and Rb, a hydrogen atom, an aliphatic hydrocarbon, and a halogen atom are mentioned independently. Examples of the aliphatic hydrocarbon include a methyl group and an ethyl group. Among these, Ra and Rb are preferably a hydrogen atom or a methyl group from the viewpoint of preventing cracks.

  Specific examples of suitable structures of the binder resin are shown below. These specific examples are shown for illustration, and any known binder resin may be mixed and used as long as it does not contradict the gist of the present invention.

By providing a cross-linked structure to the binder resin or charge transport material on the outermost surface layer, improvement of cracks can be expected, but from the viewpoint of productivity when used with silica and reduction of residual potential when used repeatedly, the cross-linked structure It is preferable that it is resin which does not have.
The ratio between the binder resin and the charge transport material is preferably 30 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of stability and charge mobility when the charge transport material is repeatedly used. 40 parts by mass or more is more preferable. On the other hand, from the viewpoints of thermal stability and abrasion resistance of the photosensitive layer, it is preferable to use the charge transport material in a ratio of usually 150 parts by mass or less. Especially, 120 mass parts or less are more preferable from a compatible viewpoint of charge transport material and binder resin, and 60 mass parts or less are especially preferable.

  The lower limit of the viscosity average molecular weight (Mv) is usually 20,000 or more, preferably 30,000 or more, more preferably 40,000 or more, from the viewpoint of the dispersibility of the silica particles. From the viewpoint of preventing filming, the upper limit is usually 200,000 or less, preferably 100,000 or less, and more preferably 80,000 or less. When the viscosity average molecular weight (Mv) is excessively small, the mechanical strength when obtained as a film for forming a photoconductor tends to decrease. Moreover, when a viscosity average molecular weight (Mv) is too large, the viscosity as a coating liquid will rise and it may become difficult to apply | coat to a suitable film thickness.

The thickness of the charge transport layer is not particularly limited, but from the viewpoint of electrical characteristics and image stability, and further from the viewpoint of high resolution, it is usually preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 35 μm or less, and still more preferably. 15 μm or more and 25 μm or less.
In order to improve the film forming property, flexibility, coating property, stain resistance, gas resistance, light resistance, etc. in the charge transport layer, or to further improve the mechanical strength of the photosensitive layer, a known plasticizer, It is also preferable to add additives such as a lubricant, a dispersion aid, an antioxidant, an ultraviolet absorber, an electron-withdrawing compound, a dye, a pigment, a sensitizer, a leveling agent, a stabilizer, a fluidity-imparting agent, and a crosslinking agent. . Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of dyes and pigments include various pigment compounds and azo compounds. Examples of leveling agents include silicone oil and fluorine-based surfactants.

  Electron-withdrawing compounds include tetracyanoquinodimethane, dicyanoquinomethane, cyano compounds such as aromatic esters having a dicyanoquinovinyl group, nitro compounds such as 2,4,6-trinitrofluorenone, and condensation of perylene. Polycyclic aromatic compounds, diphenoquinone derivatives, quinones, aldehydes, ketones, esters, acid anhydrides, phthalides, metal complexes of substituted and unsubstituted salicylic acid, metal salts of substituted and unsubstituted salicylic acid, aromatic carboxylic acids And metal salts of aromatic carboxylic acids. Preferably, cyanide compounds, nitro compounds, condensed polycyclic aromatic compounds, diphenoquinone derivatives, metal complexes of substituted and unsubstituted salicylic acid, metal salts of substituted and unsubstituted salicylic acid, metal complexes of aromatic carboxylic acid, aromatic carboxylic acid Metal salts are used

<Method for forming each layer>
Each layer constituting the photoreceptor is formed by immersing, coating, spraying, nozzle coating, bar coating, roll coating, blade coating, etc., on a support, a coating solution obtained by dissolving or dispersing a substance contained in each layer in a solvent. In this method, the coating and drying steps are sequentially repeated for each layer.

Although there is no particular limitation on the solvent or dispersion medium used for the production of the photosensitive layer, specific examples include ethers such as tetrahydrofuran, 1,4-dioxane and dimethoxyethane, esters such as methyl formate and ethyl acetate, acetone, Ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene and xylene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, Chlorinated hydrocarbons such as 1,2-dichloropropane and trichloroethylene, nitrogen-containing compounds such as n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, and triethylenediamine, acetonitrile, N-methylpyrrole Emissions, 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 the 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 appropriately determined so that the physical properties such as the solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
In the case of the charge transport layer, the solid content concentration of the coating solution is usually 5% by mass or more, preferably 10% by mass or more, and 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 the charge generation layer, 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 application method of the coating liquid include dip coating, spray coating, spinner coating, bead coating, wire bar coating, blade coating, roller coating, air knife coating, and curtain coating. Other known coating methods can also be used.

<Image forming apparatus>
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 cleaning processes. Also good.
An embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

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, a transfer device 5, a cleaning device 6 and a fixing device as necessary. A device 7 is provided.
The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are disposed along the outer peripheral surface of the electrophotographic photosensitive member 1.

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 1, the charging device 2 shows a charging roller. When operating as an image forming apparatus, the charge transport layer (outermost surface layer) has a contact portion with a charging roller. Due to the contact portion with the charging roller, charging can be performed more efficiently than corona charging such as corotron or scorotron, and chemical damage to the photoreceptor is small. The contact portion may be a part of the surface of the charge transport layer or the whole.

  If the charging roller and the photoconductor are left in contact with each other for a long time, a crack-like defect may occur on the surface of the photoconductor at the contact portion, which may cause a problem in the image. In order to solve this problem, when the image forming apparatus is not operated, it is preferable to provide a resin film between the members or to use a spacer so that the charging roller and the photosensitive member are not temporarily in contact with each other.

In many cases, the electrophotographic photosensitive member 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge including both of them (hereinafter also referred to as a photosensitive cartridge). For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be detached from the image forming apparatus main body, and another new photoreceptor cartridge can be mounted on the image forming apparatus main body. In addition, toner to be described later is also stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the toner cartridge used is exhausted, the toner cartridge is removed from the main body of the image forming apparatus. It is possible to remove the toner cartridge and install another new toner cartridge. Further, it is preferable to use a cartridge provided with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a short wavelength of 380 nm to 500 nm. .

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component conductive toner development, two-component magnetic brush development, or a wet development method can be used. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicon resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.
The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed of a resin blade such as silicon resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with resin. The regulating member 45 contacts the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 5 to 500 g / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method, or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like that are disposed to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

  The cleaning device 6 is not particularly limited, and any cleaning device such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, or a blade cleaner can be used. However, the present invention is effective for a blade cleaner. Is easy to demonstrate. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner.

  The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. The upper and lower fixing members 71 and 72 include a fixing roll in which a metal base tube made of stainless steel, aluminum or the like is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, a fixing sheet, or the like. A member can be used. Further, the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve the releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

  When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P. The type of the fixing device is not particularly limited, and a fixing device of any type such as heat roller fixing, flash fixing, oven fixing, pressure fixing, etc. can be provided including those used here.

In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.
Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.
When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.
In addition to the above-described configuration, the image forming apparatus may be configured to perform, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.
The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform processes such as a pre-exposure process and an auxiliary charging process, may be configured to perform offset printing, and may be configured with a plurality of types. A full-color tandem system configuration using toner may be used.

<Manufacture of coating liquid for undercoat layer formation>
[Coating fluid A1]
A rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were added to a Henschel mixer. 1 kg of a raw slurry obtained by mixing 50 parts of surface-treated titanium oxide obtained by mixing with 120 parts of methanol, and using a zirconia bead having a diameter of about 100 μm (YTZ manufactured by Nikkato Co., Ltd.) as a dispersion medium, a mill volume of about 0 Using a 15-liter Ultra Apex Mill (UAM-015 type) manufactured by Kotobuki Kogyo Co., Ltd., a titanium oxide dispersion was prepared by dispersing for 1 hour in a liquid circulation state with a rotor peripheral speed of 10 m / second and a liquid flow rate of 10 kg / hour .

  The titanium oxide dispersion, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula Compound represented by (B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula (E ) And a copolymerized polyamide pellet having a composition molar ratio of 75% / 9.5% / 3% / 9.5% / 3% while stirring and mixing the mixture to obtain polyamide pellets. After dissolution, ultrasonic dispersion treatment with an ultrasonic transmitter with an output of 1200 W is performed for 1 hour, and a PTFE membrane filter with a pore size of 5 μm ( The weight ratio of the surface-treated titanium oxide / copolymerized polyamide is 3/1, and the weight ratio of the mixed solvent of methanol / 1-propanol / toluene is 7/1/2. The undercoat layer forming coating solution A1 having a solid content concentration of 18.0% by weight was obtained.

<Manufacture of coating solution for forming charge generation layer>
[Synthesis Example 1]
Oxytitanium phthalocyanine was prepared based on Example 2 described in JP-A-2-289658. The obtained oxytitanium phthalocyanine (15 parts) and φ1.0-1.4 mm glass beads (170 parts) were filled in a polybin and treated with a dye dispersion tester (paint shaker) for 20 hours (mechanical grinding treatment). The oxytitanium phthalocyanine after milling was peeled from the glass beads, added to 250 parts of water after peeling, and stirred at room temperature for 30 minutes. Thereafter, 31 parts of o-dichlorobenzene was added, and the mixture was further stirred at room temperature for 1 h. After stirring, water was separated, 250 parts of methanol was added, and the mixture was stirred and washed at room temperature for 1 hour. After washing, it is filtered, and again stirred and washed with 250 parts of methanol for 1 hour, filtered, and dried by heating in a vacuum dryer to obtain CuKα characteristic X-rays (wavelength 1.541２) as shown in FIG. The main diffraction peaks at Bragg angles (2θ ± 0.2 °) of 7.3 °, 9.5 °, 11.6 °, 14.2 °, 18.0 °, 24.3 ° and 27.2 ° 14.3 parts of oxytitanium phthalocyanine (CG1) having was obtained.

[Synthesis Example 2]
Β-type oxytitanium phthalocyanine was prepared in the order of “Production Example of Crude TiOPc” and “Example 1” described in JP-A-10-7925. 18 parts of the obtained β-type oxytitanium phthalocyanine was added to 720 parts of 95% concentrated sulfuric acid cooled to −10 ° C. or lower. At this time, the sulfuric acid solution was slowly added so that the internal temperature did not exceed -5 ° C. After completion of the addition, the concentrated sulfuric acid solution was stirred at −5 ° C. or lower for 2 hours. After stirring, the concentrated sulfuric acid solution was filtered through a glass filter, the insoluble matter was filtered off, and then the concentrated sulfuric acid solution was released into 10800 parts of ice water to precipitate oxytitanium phthalocyanine, followed by stirring for 1 hour after the release. After stirring, the solution was filtered off, and the resulting wet cake was again washed in 900 parts of water for 1 hour and filtered. By repeating this washing operation until the ionic conductivity of the filtrate reached 0.5 mS / m, 185 parts of a wet cake of low crystalline oxytitanium phthalocyanine was obtained. (Oxytitanium phthalocyanine content 9.5%) 93 parts of a wet cake of the obtained low crystalline oxytitanium phthalocyanine was added to 190 parts of water and stirred at room temperature for 30 minutes. Thereafter, 39 parts of o-dichlorobenzene was added, and the mixture was further stirred at room temperature for 1 h. After stirring, water was separated, 134 parts of methanol was added, and the mixture was stirred and washed at room temperature for 1 hour. After washing, the product is filtered, and again stirred and washed with 134 parts of methanol for 1 hour, filtered, and dried by heating in a vacuum dryer to obtain CuKα characteristic X-rays (wavelength 1.541３) as shown in FIG. The main diffraction peaks at Bragg angles (2θ ± 0.2 °) of 7.3 °, 9.5 °, 11.6 °, 14.2 °, 18.0 °, 24.3 ° and 27.2 ° 7.8 parts by weight of oxytitanium phthalocyanine (CG2) was obtained.

[Coating fluid B1]
As a charge generation material, 20 parts of oxytitanium phthalocyanine (CG1) produced in Synthesis Example 1 and 280 parts of 1,2-dimethoxyethane were mixed, and pulverized with a sand grind mill for 2 hours for atomization dispersion treatment. Subsequently, 253 parts of 1,2-dimethoxyethane was added to polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.), and 4-methoxy-4-methyl-2-butylene. A binder solution obtained by dissolving pentanone in 85 parts of a mixed solution and 230 parts of 1,2-dimethoxyethane were mixed to obtain a charge generation layer forming coating solution B1.

[Coating fluid B2]
A charge generation layer forming coating solution B2 was prepared in the same manner as the coating solution B1, except that CG2 was used instead of CG1 as the charge generation material.

<Manufacture of coating liquid for charge transport layer formation>
[Coating liquid C1]
Silicon oxide with an average primary particle size of 0.8 μm surface-treated with hexamethylene disilazane (manufactured by Nippon Shokubai Co., Ltd., product name KE-S100, surface treatment, sphericity 1.0, density 2.2 g / cm ³ ) Was subjected to ultrasonic dispersion with a tetrahydrofuran solvent for 4 hours to obtain a silicon oxide slurry. 100 parts of a polycarbonate resin represented by the following repeating structure (resin BD1, viscosity average molecular weight 40,000), synthesized as a charge transport material based on “Example 1” of JP-A-2002-80432, the following structure 50 parts of a mixture consisting of a compound group of geometric isomers having a structure represented by the formula CT1 as a main component, 4 parts of a compound AD1 represented by the following formula, 0.5 part of AD2, 1 part of AD3, AD4 1 part of dimethylpolysiloxane was heated and stirred with a tetrahydrofuran solvent and the above silicon oxide slurry was stirred and mixed, and then stirred with Primemix Homomixer Mark II 2.5, and finally, binder resin / charge transport The mass ratio of substance / silicon oxide / AD1 / AD2 / AD3 / AD4 is 100/50/10/4 / 0.5 / 1/1, and the solid content is 2. A coating liquid C1 for forming a charge transport layer of 0% by mass was obtained.

[Coating fluid C2]
Instead of the polycarbonate resin BD1 used for the charge transport layer forming coating solution C1, 80 parts of the resin BD1 and 20 parts of a polycarbonate resin represented by the following repeating structure (resin BD2, viscosity average molecular weight 51,000) were used. Except for the above, a coating solution C2 for forming a charge transport layer was prepared in the same manner as C1.

[Coating fluid C3]
Instead of the polycarbonate resin BD1 used in the charge transport layer forming coating solution C1, 60 parts of a polycarbonate resin represented by the following repeating structure (resin BD3, viscosity average molecular weight 51,000), represented by the following repeating structure: A coating solution C3 for forming a charge transport layer was prepared in the same manner as C1, except that 20 parts of polycarbonate resin (resin BD4, viscosity average molecular weight 50,000) and 20 parts of resin BD2 were used.

[Coating fluid C4]
The same as C1 except that 100 parts of polycarbonate resin (resin BD5, viscosity average molecular weight 52,000) represented by the following repeating structure was used instead of polycarbonate resin BD1 used in coating solution C1 for charge transport layer formation. Thus, a charge transport layer forming coating solution C4 was prepared.

[Coating fluid C5]
The same as C1 except that 100 parts of polycarbonate resin (resin BD6, viscosity average molecular weight 49,000) represented by the following repeating structure was used instead of polycarbonate resin BD1 used in coating solution C1 for charge transport layer formation. Thus, a charge transport layer forming coating solution C5 was prepared.

[Coating fluid C6]
C2 was used except that silicon oxide having an average primary particle diameter of 0.4 μ (sphericity: 1.0, density: 2.2 g / cm ³ ) was used instead of the silicon oxide used in the charge transport layer forming coating solution C2. In the same manner as above, a coating liquid C6 for forming a charge transport layer was prepared.
[Coating fluid C7]
C2 was used except that silicon oxide having an average primary particle diameter of 1.4 μm (sphericity: 1.0, density: 2.2 g / cm ³ ) was used in place of the silicon oxide used in the charge transport layer forming coating solution C2. In the same manner as above, a charge transport layer forming coating solution C7 was prepared.

[Coating fluid C8]
A charge transport layer forming coating solution C8 was prepared in the same manner as C2, except that the charge transport layer forming coating solution C2 was changed to 20 parts of silicon oxide.
[Coating liquid C9]
A charge transport layer forming coating solution C9 was prepared in the same manner as C2, except that the charge transport layer forming coating solution C2 was changed to 5 parts of silicon oxide.

[Coating fluid C10]
A charge transport layer forming coating solution C10 was prepared in the same manner as C1, except that CT2 represented by the following formula was used instead of the charge transport material CT1 used in the charge transport layer forming coating solution C1.

[Coating liquid C11]
Instead of the polycarbonate resin BD1 used in the coating liquid C1 for charge transport layer formation, 100 parts of a polycarbonate resin represented by the following repeating structure (resin BD7, viscosity average molecular weight 50,000) is used instead of the charge transport material CT1. A coating solution C11 for forming a charge transport layer was prepared in the same manner as C1, except that CT2 was used.

[Coating fluid C12]
The coating solution for forming the charge transport layer is the same as C11 except that the silicon oxide used for the coating solution for forming the charge transport layer C11 is not used and the solvent is a tetrahydrofuran / toluene (8/2 (weight ratio)) mixed solvent. C12 was prepared.
[Coating fluid C13]
A charge transport layer forming coating solution C13 was prepared in the same manner as C1, except that 100 parts of the resin BD7 was used instead of the polycarbonate resin BD1 used in the charge transport layer forming coating solution C1.

[Coating fluid C14]
The coating solution for forming the charge transport layer is the same as C13 except that the silicon oxide used for the coating solution for forming the charge transport layer C13 is not used and the solvent is a tetrahydrofuran / toluene (8/2 (weight ratio)) mixed solvent. C14 was prepared.
[Coating solution C15]
Similar to C1, except that 100 parts of resin BD7 was used instead of polycarbonate resin BD1 used for coating liquid C1 for charge transport layer formation, and CT3 represented by the following formula was used instead of charge transport material CT1. Thus, a coating liquid C15 for forming a charge transport layer was prepared.

[Coating fluid C16]
The coating solution for forming the charge transport layer is the same as C15 except that the silicon oxide used for the coating solution for forming the charge transport layer C15 is not used and the solvent is a tetrahydrofuran / toluene (8/2 (weight ratio)) mixed solvent. C16 was prepared.
[Coating fluid C17]
The same as C1 except that 100 parts of polycarbonate resin (resin BD8, viscosity average molecular weight 40,000) represented by the following repeating structure was used instead of the polycarbonate resin BD1 used for the coating liquid C1 for charge transport layer formation. Thus, a charge transport layer forming coating solution C17 was prepared.

[Coating fluid C18]
The same as C1 except that 100 parts of polycarbonate resin (resin BD9, viscosity average molecular weight 35,000) represented by the following repeating structure was used instead of polycarbonate resin BD1 used in coating solution C1 for charge transport layer formation. Thus, a charge transport layer forming coating solution C18 was prepared.

[Coating fluid C19]
Except for using silicon oxide having an average primary particle diameter of 16 nm (manufactured by Nippon Aerosil Co., Ltd., product name R972, density 2.2 g / cm ³ ) instead of silicon oxide used in the coating liquid C2 for charge transport layer formation, In the same manner as C2, a coating liquid C19 for forming a charge transport layer was prepared.
[Coating solution C20]
C2 was used except that silicon oxide having an average primary particle diameter of 2.2 μm (sphericity: 1.0, density: 2.2 g / cm ³ ) was used in place of the silicon oxide used in the charge transport layer forming coating solution C2. In the same manner as above, a charge transport layer forming coating solution C20 was prepared.
[Coating fluid C21]
A charge transport layer forming coating solution C21 was prepared in the same manner as C2, except that 40 parts of silicon oxide was used in the charge transport layer forming coating solution C2.

<Manufacture of photosensitive drum>
[In case of underlayer]
A coating solution for forming an undercoat layer, a coating solution for forming a charge generation layer produced in a manufacturing example of a coating solution on a cylinder made of an aluminum alloy having an outer diameter of 30 mm, a length of 246 mm, and a wall thickness of 0.75 mm. The coating solution for forming the charge transport layer is sequentially applied and dried by the dip coating method, and the undercoat layer, the charge generation layer, and the charge transport are adjusted so that the film thickness after drying becomes 1.5 μm, 0.5 μm, and 18 μm, respectively. A layer was formed to produce a photoreceptor drum. The charge transport layer was dried at 125 ° C. for 24 minutes.

[In the case of anodization]
The surface of a cylinder made of an aluminum alloy having an outer diameter of 30 mm, a length of 246 mm, and a wall thickness of 0.75 mm is anodized and then sealed with a sealant mainly composed of nickel acetate. As a result, an anodic oxide coating (alumite coating) of about 6 μm was formed. Next, the charge generation layer forming coating solution and the charge transport layer forming coating solution are sequentially applied by a dip coating method and dried, and the charge generation layer is formed so that the film thicknesses after drying are 0.5 μm and 18 μm, respectively. Then, a charge transport layer was formed to produce a photosensitive drum. The charge transport layer was dried at 125 ° C. for 24 minutes.

<Image test>
The obtained photoconductor is mounted on a cyan photoconductor cartridge of a tandem full-color printer C711dn (DC roller charging, LED exposure, contact non-magnetic single component development) manufactured by Oki Data Co., Ltd., with an air temperature of 10 ° C. and a relative humidity of 15%. Below, one-sheet intermittent printing of 12,500 sheets was performed at a printing rate of 1%. After printing 12,500 sheets, a halftone image was printed, and filming (attachment of toner component) and dot reproducibility were determined as follows. Further, the film thickness before and after printing was measured, and the amount of film reduction in terms of 10,000 sheets was calculated. The results are shown in Table 1.
Filming A: There is no toner adhesion on the drum and no problem is observed in the image. O: A small amount of toner adhesion exists on the drum, but no problem is observed in the image. Δ: A large amount of toner on the drum. Although there is adhesion, no problem is observed in the image. ×: Dot reproducibility in which there is a large amount of toner adhesion on the drum and a defect corresponding to the image is also observed. ◎: There is no missing dot. A good image even in the far eye ○: A small amount of missing dot exists, but a good image in the far eye Δ: A small amount of missing dot exists, but a good image in the far eye ×: Dot There is a gap in the image, and even in the distance, the image is uneven

<Storage test>
The obtained photoreceptor is mounted on a cyan photoreceptor cartridge of a tandem full-color printer C711dn (DC roller charging, LED exposure, contact non-magnetic single component development) manufactured by Oki Data Co., Ltd., temperature 55 ° C., relative humidity 85% Stored below for 1 month. Thereafter, a halftone image was printed at a temperature of 25 ° C. and a relative humidity of 50%, and a determination was made. Next, the photoconductor was taken out from the cartridge, and the surface of the photoconductor was observed.
Image ○: No defect is observed in the image △: Image defect is slightly observed corresponding to the portion where the charging roller was in contact ×: Image defect corresponding to the portion where the charging roller was in contact Photoreceptor surface to be observed ○: No defects are observed on the surface of the photoreceptor. Δ: A few crack-like defects are observed in the portion where the charging roller is in contact. ×: Many cracks are present in the portion where the charging roller is in contact. Defects can be seen

<Solubility>
At a temperature of 25 ° C., a saturated toluene solution of a charge transport material is prepared, and the weight at this time is measured. The saturated solution is then dried and the weight of the remaining solid is measured. Solubility (% by weight) was calculated from the ratio of the weight of the solid to the weight of the saturated solution.

[Examples 1 to 11 and Comparative Examples 1 to 11]
Photosensitive drums were prepared and evaluated using the undercoat layer forming coating solution or anodizing treatment, charge generation layer forming coating solution, and charge transport layer forming coating solution shown in Table 1. The results are shown in Table-1. Table 2 shows the molecular weight of the repeating unit of the binder resin, and Table 3 shows the solubility of the charge transport material in toluene.

[Example 12]
A resin film was sandwiched between contact portions of the obtained photoreceptor and the charging roller, and a storage test was performed in a state where the photoreceptor and the charging roller were not in direct contact.
[Example 13]
A storage test was performed with a resin spacer sandwiched between the ends of the charging roller and the photoreceptor and the charging roller not in direct contact.

From Table-1, filming can be prevented by containing silica particles of 0.1 μm or more and 1.5 μm or less in the outermost surface layer. In particular, the average primary particle diameter contains silica particles of 0.3 to 1.0 μm, and by using a specific binder resin, the content of silica particles is 3 to 20 wt% of the entire charge transport layer, As for filming, dot reproducibility, and cracks, good results were obtained. In particular, when the silica particle content was 5 to 15 wt% of the entire charge transport layer, a more excellent effect was obtained.

  As shown in Comparative Examples 1, 3, 5, 7, and 8, when silica particles are used, a binder resin other than the present invention causes image defects due to cracks in a storage test. As shown in Comparative Examples 2, 4, and 6, when silica particles are not used, filming occurs although cracks are good. As can be seen from the comparison between Example 1 and Example 10, it can be seen that cracks are further improved by using a charge transport material having a specific solubility.

Claims (13)

An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an image exposing unit for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image, and developing the electrostatic latent image with toner In an electrophotographic cartridge having developing means for
The charging means is contact roller charging;
The electrophotographic photoreceptor has a charge generation layer and a charge transport layer in this order on a conductive substrate. The charge transport layer is a single layer and an outermost surface layer. The charge transport material has a molecular weight of 210 or more and 290. A binder resin having a repeating structural unit, and silica particles having an average primary particle size of 0.1 μm or more and 1.5 μm or less,
The electrophotographic cartridge according to claim 1, wherein the content of the silica particles is 3 to 20 wt% of the entire charge transport layer.   The electrophotographic cartridge according to claim 1, wherein an average primary particle diameter of the silica particles is 0.3 μm or more and 0.9 μm or less.   The electrophotographic cartridge according to claim 1, wherein the silica particles are surface-treated with a reactive organosilicon compound.   The electrophotographic cartridge according to claim 1, wherein the sphericity of the silica particles is 0.95 or more and 1.0 or less. The electrophotographic cartridge according to claim 1, wherein the density of the silica particles is 1.5 g / cm ³ or more and 3.0 g / cm ³ . The electrophotographic cartridge according to claim 1, wherein the content of the silica particles is 5 to 15 wt% of the entire charge transport layer. The electrophotographic cartridge according to claim 1, wherein the binder resin has a repeating structure represented by the following formula (1).

(In formula (1), R ¹ and R ² each independently represent hydrogen or a methyl group.)   The electrophotographic cartridge according to any one of claims 1 to 7, wherein the solubility of the charge transport material in toluene is 10% or more.   The electrophotographic cartridge according to claim 1, wherein the charging roller is disposed so as not to directly contact the charge transport layer.   An image forming apparatus using the electrophotographic cartridge according to claim 1. In an electrophotographic photosensitive member charged by a charging roller used in an image forming apparatus, a conductive support;
A charge generation layer;
A charge transport layer of a single layer and an outermost surface layer, having a contact portion with the charging roller, a charge transport material, a binder resin having a repeating structural unit having a molecular weight of 210 to 290, and an average primary particle size Containing 0.1 to 1.5 μm silica particles, and the content of the silica particles is 3 to 20 wt% of the entire charge transporting layer;
An electrophotographic photoreceptor, wherein a charge generation layer and a charge transport layer are laminated in this order on the conductive support.   The electrophotographic photosensitive member according to claim 11, wherein the sphericity of the silica particles is 0.95 or more and 1.0 or less. The electrophotographic photosensitive member according to claim 11 or 12, wherein the density of the silica particles is 1.5 g / cm ³ or more and 3.0 g / cm ³ or less.

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