JP2011227486A - Electrophotographic photoreceptor, image forming method, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which is excellent in the stability of the liquid properties and the electric characteristics over time, excellent in both of the electric characteristics and the mechanical strength when a photosensitive layer is formed, and also excellent in the stability of coating liquid.SOLUTION: A coating liquid for forming a photoreceptive layer is made containing with a polyarylate resin including a repeating structure represented by formula (1), and in addition, the number of parts of added charge transport material is adjusted, so that an electrophotographic photoreceptor, which is excellent in the stability of the coating liquid over time and excellent in both of the electric characteristics and the mechanical strength when a photosensitive layer is formed, is obtained.

Description

  The present invention relates to a coating solution for forming a photosensitive layer for forming a photosensitive layer of an electrophotographic photosensitive member used in a copying machine, a printer, and the like, as well as an electrophotographic photosensitive member, an electrophotographic photosensitive member cartridge, and an image forming apparatus. More particularly, the present invention relates to a coating solution for forming a photosensitive layer having excellent coating solution stability, and an electrophotographic photosensitive member, an electrophotographic photosensitive member cartridge, and an image forming apparatus having excellent mechanical strength and excellent electrical characteristics. .

Electrophotographic technology is widely used in fields such as copiers and various printers because of its immediacy and high quality images.
For the electrophotographic photoreceptor (hereinafter referred to as “photoreceptor” as appropriate) which is the core of the electrophotographic technology, an organic photoconductive material having advantages such as non-polluting, easy film formation and easy production was used. A photoconductor is used.

  Photosensitive materials using organic photoconductive materials include so-called dispersive photoconductors in which photoconductive fine powder is dispersed in a binder resin, and laminated photoconductors in which a charge generation layer and a charge transport layer are stacked. Are known. In the laminated type photoconductor, a highly sensitive photoconductor can be obtained by combining a charge generating material and a charge transport material having high efficiency, a photoconductor having a wide material selection range and a high safety can be obtained. The layer can be easily formed by coating, has high productivity, and is advantageous in terms of cost. Therefore, it is the mainstream of photoreceptors, and has been developed and put into practical use.

  Since the electrophotographic photosensitive member is repeatedly used in an electrophotographic process, that is, a cycle of charging, exposure, development, transfer, cleaning, static elimination, etc., it is deteriorated by various stresses during that time. Such deterioration includes, for example, strong oxidation ozone and NOx generated from a corona charger used as a charger, which causes chemical damage to the photosensitive layer, or a carrier generated by image exposure or static elimination light. There are chemical and electrical deteriorations such as flowing in the photosensitive layer and decomposition of the photosensitive layer composition by external light.

  In addition to this, mechanical degradation such as abrasion of the photosensitive layer surface due to rubbing of the cleaning blade, magnetic brush, developer, contact with the transfer member or paper, scratches, and film peeling. is there. In particular, the damage generated on the surface of the photosensitive layer tends to appear on the image and directly impairs the image quality, which is a major factor that limits the life of the photoreceptor. That is, in order to develop a long-life photoconductor, it is desired to increase electrical and chemical durability, and at the same time, increase mechanical strength such as wear resistance and scratch resistance.

In the case of a general photoreceptor having no functional layer such as a surface protective layer, it is the photosensitive layer that receives such a load. The photosensitive layer is usually composed of a binder resin and a photoconductive substance, and the binder resin substantially determines the strength. However, since the doping amount of the photoconductive substance is considerably large, the conventional technique has not yet provided sufficient mechanical strength.
In addition, due to the increasing demand for high-speed printing, materials that can cope with higher-speed electrophotographic processes have been demanded. When performing high-speed printing, in addition to high sensitivity and long life, the photosensitive member is also required to have good responsiveness in order to shorten the time from exposure to development. It is known that the responsiveness of the photoreceptor is governed by the charge transport layer, particularly the charge transport material, but varies greatly depending on the binder resin.

In addition, each layer constituting these electrophotographic photoreceptors usually has a coating liquid containing a photoconductive substance, a binder resin, etc. on a support, dip coating, spray coating, nozzle coating, bar coating, roll coating, It is formed by coating by blade coating or the like. In these layer forming methods, a known method such as preparing a coating solution in which a substance contained in a layer is dissolved in a solvent and applying the coating solution is applied.

In many processes, a coating solution is prepared in advance and stored. Therefore, it is desired that each of the binder resin and the charge transport material, or both, has excellent solubility in the solvent used in the coating process and that the coating solution after dissolution is stable.
Examples of the binder resin of the photosensitive layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, thermoplastic resins such as polycarbonate, polyester, polysulfone, phenoxy, epoxy, and silicone resins, and various types. The thermosetting resin is used. Among the various binder resins, the polycarbonate resin has a relatively excellent performance, and various polycarbonate resins have been developed and put into practical use (see, for example, Patent Documents 1 to 4).

On the other hand, a technique of an electrophotographic photoreceptor using the polyarylate resin of the present invention marketed under the trade name “U-polymer” as a binder is disclosed, and among them, sensitivity is particularly excellent as compared with polycarbonate. (See, for example, Patent Documents 5 and 6).
Also disclosed is a technique for an electrophotographic photoreceptor using a polyarylate resin using a dihydric phenol component having a specific structure as a binder resin, improving the solution stability during the production of the photoreceptor, mechanical strength, It is known that the wear resistance is excellent (see, for example, Patent Documents 7 and 8).

JP 50-98332 A JP 59-71057 A JP 59-184251 JP-A-5-21478 JP-A-56-135844 Japanese Patent No. 4222307 Japanese Patent Laid-Open No. 3-6567 Japanese Patent Laid-Open No. 10-288845

Conventional photoreceptors have drawbacks such as surface wear and scratches due to practical loads such as toner development, transfer member and paper friction, and cleaning member (blade) friction. Was. For this reason, in the printing using a photoconductor, the actual printing performance is limited to practical use.
In addition, the electrophotographic photosensitive member using a polyester resin known in the past often sacrifices electrical characteristics and chemical durability when the mechanical strength is improved, and is applicable to high performance and high speed machines. It was difficult. Further, depending on the content of the charge transporting material, there are problems such as poor stability when used as a photosensitive layer forming coating solution, white turbidity, precipitation, or insolubilization.

  The present invention was devised to solve the above problems, and is excellent in stability over time of a coating solution, and when an photosensitive layer is formed, an electrophotographic photoreceptor excellent in both electrical characteristics and mechanical strength, An object is to provide an electrophotographic photosensitive member cartridge and an image forming apparatus using the same.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a photoreceptor is excellent in mechanical strength by using a polyarylate resin having a specific structure, and used together with the polyarylate resin. In particular, when the amount of the charge transport material is specified, it can be seen that the electrical characteristics are improved and the stability of the coating solution can be secured, and the present invention has been completed.
That is, the gist of the present invention is an electrophotographic photosensitive member having a photosensitive layer on a conductive support, containing a polyarylate resin having a repeating structure represented by the following formula (1) as a binder resin, Furthermore, the electrophotographic photoreceptor contains 10 to 45% by weight of a charge transport material with respect to the binder resin.

At this time, the HOMO energy level E_homo obtained as a result of the structural optimization calculation by the density functional calculation B3LYP / 6-31G (d, p) of the charge transport material satisfies E_homo> −4.72 (eV). Preferred (claim 2).
Furthermore, the polarizability α is calculated by the restricted Hartree-Fock method (basic function is 6-31G (d, p)) in the stable structure obtained after the structure optimization calculation by B3LYP / 6-31G (d, p). The value αcal is
It is preferable to satisfy αcal> 60 (Å ³ ) (Claim 3).

  Still another subject matter of the present invention is the above-described electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, An electrophotographic photosensitive member cartridge comprising: at least one of developing means for developing the electrostatic latent image with toner and transfer means for transferring the toner to a transfer target (claim 4). ).

  Still another subject matter of the present invention is the above-described electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, and exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. And an image forming apparatus comprising: a developing unit that develops the electrostatic latent image with toner; and a transfer unit that transfers the toner to a transfer target.

  According to the present invention, an electrophotographic photosensitive member excellent in electrical characteristics and mechanical strength, and an electrophotographic cartridge and an image forming apparatus using the same can be obtained. Further, sufficient stability of the coating solution for forming the photosensitive layer can be secured.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. It is an X-ray diffraction diagram showing a powder X-ray diffraction spectrum of oxytitanium phthalocyanine used in Examples and Comparative Examples of the present invention. It is the graph which showed the load curve with respect to indentation depth.

Hereinafter, the best mode for carrying out the present invention will be described in detail. In the present invention,
The present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the invention.
[Electrophotographic photoreceptor]
<Conductive support>
As the conductive support used for the photoreceptor, for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powders 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. As a form, a drum shape, a sheet shape, a belt shape or the like is used. For conductive support of metallic materials, for control of conductivity and surface properties, and for defect coating. A conductive material having an appropriate resistance value may be applied.

When a metal material such as an aluminum alloy is used as the conductive support, it may be used after an anodized film is applied. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
For example, it is formed by anodizing in an acidic bath of chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc., but anodizing in sulfuric acid gives better results. In the case of anodic oxidation in sulfuric acid, the sulfuric acid concentration is 100-300 g / l, the dissolved aluminum concentration is 2-15 g / l, the liquid temperature is 15-30 ° C., the electrolysis voltage is 10-20 V, and the current density is 0.5-. Although it is preferable to set within the range of 2A / dm2, it is not limited to the above conditions.

It is preferable to perform a sealing treatment on the anodic oxide film thus formed. The sealing treatment may be performed by a normal method. For example, the low-temperature sealing treatment is performed by immersion in an aqueous solution containing nickel fluoride as a main component, or the high-temperature sealing is performed by immersion in an aqueous solution containing nickel acetate as a main component. It is preferable that the treatment is performed.
The concentration of the nickel fluoride aqueous solution used in the case of the low-temperature sealing treatment can be appropriately selected, but more preferable results are obtained when it is used in the range of 3-6 g / l. Further, in order to proceed the sealing treatment smoothly, the treatment temperature is 25-40 ° C., preferably 30-35 ° C., and the pH of the nickel fluoride aqueous solution is 4.5-6.5, preferably It is better to process in the range of 5.5-6.0. As the pH adjuster, oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, sodium acetate, aqueous ammonia and the like can be used. The treatment time is preferably in the range of 1 to 3 minutes per 1 μm of film thickness. In order to further improve the physical properties of the film, cobalt fluoride, cobalt acetate, nickel sulfate, a surfactant or the like may be added to the nickel fluoride aqueous solution. Subsequently, it is washed with water and dried to finish the low temperature sealing treatment.

  As the sealing agent in the case of the high temperature sealing treatment, an aqueous solution of a metal salt such as nickel acetate, cobalt acetate, lead acetate, nickel acetate-cobalt, barium nitrate can be used, and it is particularly preferable to use nickel acetate. . The concentration in the case of using an aqueous nickel acetate solution is preferably in the range of 5-20 g / l. The treatment temperature is 80-100 ° C., preferably 90-98 ° C., and the pH of the nickel acetate aqueous solution is preferably 5.0-6.0. Here, ammonia water, sodium acetate, or the like can be used as the pH adjuster. The treatment time is 10 minutes or longer, preferably 20 minutes or longer. In this case as well, sodium acetate, organic carboxylic acid, anionic and nonionic surfactants may be added to the nickel acetate aqueous solution in order to improve the film properties.

Subsequently, it is washed with water and dried to finish the high temperature sealing treatment. When the average film thickness is thick, stronger sealing conditions are required due to the higher concentration of the sealing liquid and high temperature / long-time treatment. Accordingly, productivity is deteriorated and surface defects such as spots, dirt, and dusting are likely to occur on the coating surface. From such a point, it is preferable that the average film thickness of the anodic oxide coating is usually 20 μm or less, particularly 7 μm or less.

  The support surface may be smooth, or may be roughened by using a special cutting method or polishing. 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 cutting. In particular, when using a non-cutting aluminum substrate such as drawing, impact processing, ironing, etc., it is preferable because the treatment eliminates dirt, foreign matter, and other foreign matters, small scratches, etc., and a uniform and clean substrate can be obtained. .

<Underlayer>
An undercoat layer may be provided between the conductive support and the photosensitive layer described later for improving adhesion and blocking properties. As the undercoat layer, a resin, a resin in which particles such as a metal oxide are dispersed, or the like is used.
Examples of the metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium titanate and barium titanate. Only one type of particles may be used, or a plurality of types of particles may be mixed and used. Among these metal particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicone. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may contain.

Various particle diameters of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle diameter is preferably 10 nm or more and 100 nm or less, and particularly preferably 10 nm. It is 50 nm or less. This average primary particle size can be obtained from a TEM photograph or the like.
The undercoat layer is preferably formed in a form in which the metal oxide particles are dispersed in a binder resin. The binder resin used for the undercoat layer is epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, chloride Vinylidene resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacrylic acid resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, cellulose such as nitrocellulose Ester resin, cellulose ether resin, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelate compound, zirconium The organic zirconium compound alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanyl alkoxide compound, be a known binder resin such as a silane coupling agent can. These can be used alone or in a cured form together with a curing agent. Among these, alcohol-soluble copolymerized polyamide, modified polyamide, and the like are preferable because they exhibit good dispersibility and coatability.

The addition ratio of the inorganic particles to the binder resin used for the undercoat layer can be arbitrarily selected, but from the viewpoint of dispersion stability and coating properties, the binder resin is usually 10% by mass or more, It is preferable to use in the range of 500 mass% or less.
The thickness of the undercoat layer is arbitrary as long as the effects of the present invention are not significantly impaired, but the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and coating properties during production of the electrophotographic photosensitive member. Therefore, it is usually 0.01 μm or more, preferably 0.1 μm or more, and usually 30 μm or less, preferably 20 μm or less. A known antioxidant or the like may be mixed in the undercoat layer. The undercoat layer may contain pigment particles, resin particles and the like for the purpose of preventing image defects.

<Photosensitive layer>
The photosensitive layer is formed on the above-mentioned conductive support (or on the undercoat layer when the above-described undercoat layer is provided). The photosensitive layer is a layer containing a charge transport material specified in the present application. As a type of the photosensitive layer, the charge generation material and the charge transport material (including the charge transport material specified in the present application) exist in the same layer. Having a single layer structure dispersed in a binder resin (hereinafter referred to as “single layer type photosensitive layer” as appropriate), a charge generation layer in which a charge generation material is dispersed in a binder resin, and a charge transport material (specified in this application). A functionally separated layered structure composed of two or more layers, including a charge transporting layer dispersed in a binder resin (hereinafter referred to as “laminated photosensitive layer” as appropriate). However, any form may be used.

In addition, as the laminated photosensitive layer, a charge-generating layer and a charge transport layer are laminated in this order from the conductive support side, and conversely, a charge transport layer and a charge generation layer are formed from the conductive support side. There are reverse laminated photosensitive layers provided in order, and any of them can be adopted, but a forward laminated photosensitive layer that can exhibit the most balanced photoconductivity is preferable.
<Functional separation type photosensitive layer>
<Charge generation layer>
The charge generation layer of the laminated photosensitive layer (function-separated type photosensitive layer) contains a charge generation material, and usually contains a binder resin and other components used as necessary. Such a charge generation layer is prepared by, for example, preparing a coating solution by dissolving or dispersing fine particles of a charge generation material and a binder resin in a solvent or a dispersion medium. It can be obtained by coating and drying on the top (on the undercoat layer when an undercoat layer is provided) and on the charge transport layer in the case of a reverse laminated type photosensitive layer.

<Charge generating material>
The charge generating material may be used alone or in a mixed state with several dyes and pigments.
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. Organic photoconductive materials are preferred, and organic photoconductive materials are particularly preferable. Pigments are 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 as dyes used in the mixed state from the viewpoint of photosensitivity. When organic pigments are used as the charge generation material, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

  When a phthalocyanine pigment is used as the charge generation material, specifically, metal-free phthalocyanine and metal-containing phthalocyanine are used. Specific examples of metal-containing phthalocyanines include metals such as copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, or their oxides, halides, hydroxides, alkoxides, and the like. Various crystal forms of phthalocyanines are used. In particular, titanyl phthalocyanines (also known as oxytitanium phthalocyanine) such as A type (also known as β type), B type (also known as α type), D type (also known as Y type), vanadyl phthalocyanine, chloroindium phthalocyanine, which are highly sensitive crystal types Chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and I, and μ-oxo-aluminum phthalocyanine dimer such as type II are suitable. is there.

  Among these phthalocyanines, A type (β type), B type (α type), D type (Y type) oxytitanium phthalocyanine, II type chlorogallium phthalocyanine, V type hydroxygallium phthalocyanine, G type μ-oxo- Gallium phthalocyanine dimer and the like are particularly preferable. In particular, oxytitanium phthalocyanine preferably has a clear diffraction peak mainly at a Bragg angle (2θ ± 0.2 °) of 27.2 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray.

  Further, the oxytitanium phthalocyanine preferably has a clear diffraction peak at a Bragg angle (2θ ± 0.2 °) of 9.0 ° to 9.7 ° in a powder X-ray diffraction spectrum by CuKα characteristic X-ray. In view of the characteristics of the electrophotographic photosensitive member, main diffraction peaks at 9.6 °, 24.1 °, 27.2 °, or 9.5 °, 9.7 °, 24.1 °, and 27.2 ° are obtained. From the viewpoint of stability at the time of dispersion, it preferably has no peak at around 26.2 °. Among the oxytitanium phthalocyanines mentioned above, 7.3 °, 9.6 °, 11.6 °, 14.2 °, 18.0 °, 24.1 ° and 27.2 °, or 7.3 °, More preferably, it has main diffraction peaks at 9.5 °, 9.7 °, 11.6 °, 14.2 °, 18.0 °, 24.2 ° and 27.2 °.

  When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a highly sensitive photoreceptor can be obtained with respect to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm. Further, when an azo pigment such as monoazo, diazo, or trisazo is used, white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength (for example, a wavelength in the range of 380 nm to 500 nm). It is possible to obtain a photoreceptor having sufficient sensitivity to the laser beam).

  The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or the mixed state in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, crystallization, etc. It may be the one that gave rise to. 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.

On the other hand, when an azo pigment is used as a charge generation material, various known azo pigments can be used as long as they have sensitivity to a light source for light input. Trisazo pigments are preferably used.
When the above organic pigment is used as the charge generation material, one kind may be used alone, or two or more kinds of pigments may be mixed and used. In this case, it is preferable to use a combination of two or more kinds of charge generating materials having spectral sensitivity characteristics in different spectral regions of the visible region and the near red region. Among them, a disazo pigment, a trisazo pigment and a phthalocyanine pigment are preferably used in combination. More preferred.

Examples of the binder resin used for the charge generation layer in the functional separation type photoreceptor include polyvinyl butyral resin, polyvinyl formal resin, polyvinyl such as partially acetalized polyvinyl butyral resin in which a part of butyral is modified with formal or acetal. Acetal resin, polyarylate resin, polycarbonate resin, polyester resin, modified ether 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, cellulose resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, Vinyl chloride-vinyl acetate such as vinyl chloride-vinyl acetate copolymer, hydroxy-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, etc. Copolymer, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, styrene-alkyd resin, silicon-alkyd resin, phenol-formaldehyde resin and other insulating resins, poly-N-vinylcarbazole, polyvinylanthracene The organic photoconductive polymer such as polyvinyl perylene can be selected and used, but is not limited to these polymers. These binder resins may be used alone or in combination of two or more.

Specifically, the charge generation layer in the function-separated type photoconductor is prepared by dispersing the above-mentioned binder resin in an organic solvent and dispersing the charge generation material to prepare a coating solution, which is then applied on the conductive support (undercoat layer is formed). If provided, it is formed by coating (on the undercoat layer).
Solvents for dissolving the binder resin and the solvent and dispersion medium used for preparing the coating liquid include, for example, saturated aliphatic solvents such as pentane, hexane, octane and nonane, aromatic solvents such as toluene, xylene and anisole, chlorobenzene, Halogenated aromatic solvents such as dichlorobenzene and chloronaphthalene, amide solvents such as dimethylformamide and N-methyl-2-pyrrolidone, alcohol solvents such as methanol, ethanol, isopropanol, n-butanol and benzyl alcohol, glycerin, Aliphatic polyhydric alcohols such as polyethylene glycol, chain solvents such as acetone, cyclohexanone, methyl ethyl ketone, and cyclic ketone solvents, ester solvents such as methyl formate, ethyl acetate, n-butyl acetate, methylene chloride, chloroform, 1, 2-dichloro Halogenated hydrocarbon solvents such as tan, chain ether and solvent such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, acetonitrile, dimethyl sulfoxide, sulfolane, hexa Examples include aprotic polar solvents such as methylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, nitrogen-containing compounds such as ethylenediamine, triethylenediamine, and triethylamine, mineral oil such as ligroin, water, etc. Those which do not dissolve the undercoat layer are preferably used. These can be used alone or in combination of two or more.

  In the charge generation layer of the function-separated type photoconductor, the blending ratio (weight) of the binder resin and the charge generation material is 10 to 1000 parts by weight, preferably 30 to 500 parts by weight with respect to 100 parts by weight of the binder resin. The film thickness is usually 0.1 μm to 10 μm, preferably 0.15 μm to 0.6 μm. 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. On the other hand, if the ratio of the charge generating substance is too low, the sensitivity as a photoreceptor may be reduced.

As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, or a sand mill dispersion method can be used. In this case, it is effective to refine the particles to a particle size of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.
<Charge transport layer>
In forming the charge transport layer of the function-separated type photoreceptor having the charge generation layer and the charge transport layer, a binder resin is used to ensure film strength.

In the case of the charge transport layer of the function-separated type photoreceptor, a coating solution obtained by dissolving or dispersing the charge transport material and the binder resin in a solvent, and in the case of a single layer type photoreceptor, the charge generation material and the charge transport material And a coating solution obtained by dissolving or dispersing the binder resin in a solvent and applying and drying.
<Binder resin>
<Polyarylate resin of the present invention>
The polyarylate resin according to the present invention is a polyarylate resin including a repeating structure represented by the following formula (1).

  The polyarylate resin represented by the formula (1) of the present invention can be obtained, for example, as trade name “U polymer” manufactured by Unitika Ltd. This is a polymer mainly composed of polyester of bisphenol component and aromatic dicarboxylic acid component, and has a balance between the electrical properties and mechanical durability, which is intermediate between commonly used polycarbonate resins and polyester resins. It is a good resin.

  Further, in the polyester resin according to the present invention, the viscosity average molecular weight is usually not less than 10,000, preferably not less than 15,000, more preferably not less than 20,000 so as to be suitable for coating formation of the photosensitive layer. Usually, it is 300,000 or less, preferably 200,000 or less, more preferably 100,000 or less. If the viscosity average molecular weight is less than 10,000, the mechanical strength of the resin may be lowered and may not be practical. If it is more than 300,000, the solubility may be lowered or the photosensitive layer may be formed to an appropriate thickness. It may be difficult to do.

  In addition, the polyester resin concerning this invention can also be used for an electrophotographic photoreceptor, using another resin together. Therefore, you may make it make the coating liquid of this invention contain another resin. Other resins used here include vinyl polymers such as polymethyl methacrylate, polystyrene, polyvinyl chloride, and copolymers thereof, polycarbonate, polyester, polyester polycarbonate, polysulfone, phenoxy, epoxy, silicone resin, etc. Examples thereof include a plastic resin and various thermosetting resins. Of these resins, polycarbonate resins and polyester resins are preferred.

In addition, the use ratio of the resin used in combination is not particularly limited, but in order to sufficiently obtain the effects of the present invention, a range not exceeding the ratio of the polyester resin according to the present invention, that is, 100 parts by weight of the binder resin of the charge transport layer. As a result, the proportion of the resin used in combination is preferably less than 50 parts by weight.
<Charge transport material>
The energy level E_homo of HOMO by structure optimization calculation using B3LYP / 6-31G (d, p) of the charge transport material of the present invention is preferably E_homo> -4.72 (eV), E_homo> -4.70 (eV) More preferably, E_homo> −4.67 (eV) is most preferable. This is because the higher the HOMO energy level, the lower the post-exposure potential and the better the electrophotographic photoreceptor. On the other hand, if E_homo is too high, problems such as reduced gas resistance and ghosting occur, so E_homo <-4.30 (eV) is preferable, E_homo <-4.50 (eV) is more preferable, E_homo <-4.56 ( eV) is most preferred.

Furthermore, the calculated value αcal of the polarizability α by the HF / 6-31G (d, p) calculation in the stable structure obtained after the structure optimization calculation using B3LYP / 6-31G (d, p) is αcal> 60 ( Å ³ ) is preferred,
αcal> 70 (Å ³ ) is more preferable, and αcal> 80 (Å ³ ) is most preferable. This is because a charge transport film containing a charge transport material having a large αcal exhibits high charge mobility, and by using the charge transport film, an electrophotographic photoreceptor excellent in chargeability and sensitivity can be obtained. On the other hand, if αcal is too large, the solubility of the charge transport material decreases, so αcal <
Preferably, 200 (200 ³ ), αcal <150 (Å ³ ), more preferably αcal <130 (Å ³ ), and most preferably αcal <110 (Å ³ ).

In the present invention, the energy level E_homo of HOMO is a type of density functional B3LYP (AD Becke, J. Chem. Phys. 98, 5648 (1993), C. Lee, W. Yang, and RG Parr, Phys. Rev. B37, 785 (1988) and B. Miehlich, A. Savin, H. Stoll, and H. Preuss, Chem. Phys. Lett. 157, 200 (1989)). I got it. At this time, 6-31G (d, p) obtained by adding a polarization function to 6-31G was used as the basis set (R. Ditchfield, WJ Hehre, and JA Pople, J. Chem. Phys. 54, 724 (1971 ), WJ Hehre, R. Ditchfield, and JA Pople, J. Chem. Phys. 56, 2257 (1972), PC Hariharan and JA
Pople, Mol. Phys. 27, 209 (1974), MS Gordon, Chem. Phys. Lett. 76, 163 (1980),
PC Hariharan and JA Pople, Theo. Chim. Acta 28, 213 (1973), J.-P. Blaudeau, MP McGrath, LA Curtiss, and L. Radom, J. Chem. Phys. 107, 5016 (1997), MM Francl, WJ Pietro, WJ Hehre, JS Binkley, DJ DeFrees, JA Pople, and MS Gordon, J. Chem. Phys. 77, 3654 (1982), RC Binning Jr. and LA
Curtiss, J. Comp. Chem. 11, 1206 (1990), VA Rassolov, JA Pople, MA Ratner, and TL Windus, J. Chem. Phys. 109, 1223 (1998), and VA Rassolov, MA
Ratner, JA Pople, PC Redfern, and LA Curtiss, J. Comp. Chem. 22, 976 (2001)). In the present invention, B3LYP calculation using 6-31G (d, p) is described as B3LYP / 6-31G (d, p).

Furthermore, the polarizability αcal is calculated using the restricted Hartree-Fock method (“Modern Quantum Chemistry”, A. Szabo and the stable structure obtained by the structure optimization calculation using B3LYP / 6-31G (d, p).
NS Ostlund, McGraw-Hill publishing company, New York, 1989). At this time, 6-31G (d, p) was used as the basis function. In the present invention, the Hartree-Fock calculation using 6-31G (d, p) is described as HF / 6-31G (d, p).

In the present invention, the program used for B3LYP / 6-31G (d, p) calculation and HF / 6-31G (d, p) calculation is Gaussian 03, Revision D. 01 (MJ Frisch, GW Trucks, HB Schlegel, GE Scuseria, MA Robb, JR Cheeseman, JA Montgomery, Jr., T. Vreven, KN Kudin,
JC Burant, JM Millam, SS lyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, GA Petersson, H. Nakatsuji, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, M. Klene, X. Li, JE Knox, HP Ilratchian, JB Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, RE Stratmann, O. Yazyev, AJ Austin,
R. Cammi, C. Pomelli, JW Ochterski, PY Ayala, K. Morokuma, GA Voth, P.
Salvador, JJ Dannenberg, VG Zakrzewski, S. Dapprich, AD Daniels, MC
Strain, O. Farkas, DK Malick, AD Rabuck, K. Raghavachari, JB Foresman,
JV Ortiz, Q. Cui, AG Baboul, S. Clifford, J. Cioslowski, BB Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, RL Martin, DJ Fox, T. Keith, MA Al- Laham, CY Peng, A. Nanayakkara, M. Challacombe, PMW Gill, B. Johnson, W. Chen, MW Wong, C. Gonzalez, and JA Pople, Gaussian, Inc., Wallingford CT, 2004.).

There is no limitation on the structure of the charge transport material satisfying the above parameters, and aromatic amine derivatives, stilbene derivatives, butadiene derivatives, hydrazone derivatives, carbazole derivatives, aniline derivatives, enamine derivatives, and a combination of these compounds, or these
An electron donating material such as a polymer having a group consisting of a BR compound in the main chain or side chain. Among these, aromatic amine derivatives, stilbene derivatives, hydrazone derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded are preferable, and those in which a plurality of enamine derivatives and aromatic amines are bonded are more preferable. .

In addition, the charge transport material having the above parameters may be used in combination with a charge transport material outside the range of the parameters of the present invention, but in order to sufficiently exhibit the above-described effects of the present invention, The charge transport material having the parameters of the present invention is usually 10% by mass or more, preferably 5%.
It is 0% by mass or more, more preferably 80% by mass or more, and most preferably 100% by mass.

  In the present invention, the charge transport material is usually 20 parts by weight or more, preferably 30 parts by weight or more, more preferably 100 parts by weight or more with respect to 100 parts by weight of the binder resin of the charge transport layer, in order to fully exhibit the effects of the present invention described above. Is 35 parts by weight or more. In addition, the charge transport material having the parameters of the present invention has an advantage that the effect can be exhibited even in a relatively small amount, and in view of wear resistance, it is preferably 45 parts by mass or less, more preferably 40 parts by mass or less. . If the number of added parts of the charge transport material is too large, wear resistance may be reduced and the charge transport material may be precipitated.

  The charge transport material having the parameters of the present invention is particularly effective when a polyarylate resin having a repeating structure represented by the formula (1) is used. When the polyarylate resin is used, the electrical characteristics are worse than when the polycarbonate resin is used, but when the charge generation material having the parameters of the present invention is used, both excellent wear resistance and electrical characteristics are achieved. be able to.

  Examples of charge transport materials are listed in Table 1 below.

In the case of a multilayer photoreceptor, the thickness of the charge transport layer is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, and usually 50 μm or less from the viewpoint of long life, image stability, and high resolution. , Preferably 45 μm or less, more preferably 30 μm or less.
<Single layer type photosensitive layer>
The single-layer type photosensitive layer is formed using a binder resin in the same manner as the charge transport layer of the function-separated type photoreceptor in addition to the charge generation material and the charge transport material. Specifically, a charge generation material, a charge transport material, and various binder resins are dissolved or dispersed in a solvent to prepare a coating solution, and on the conductive support (on the undercoat layer when an undercoat layer is provided). It can be obtained by coating and drying.

The types of the charge transport material and the binder resin and the use ratios thereof 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. The total amount of the layer-type photosensitive layer is 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.
The use ratio of the binder resin to the charge generating substance in the single-layer type photosensitive layer is such that the charge generating substance is usually 0.1 parts by mass or more, preferably 1 part by mass or more, and usually 100 parts by mass of the binder resin. It is 30 mass parts or less, Preferably it is set as 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.
The laminated photosensitive layer and single-layered photosensitive layer thus obtained have the advantage that they are more resistant to ozone and oxidizing gas generated in the machine than conventional photoreceptors. This is greatly influenced by the hardness of the binder resin represented by the general formula (1), and the charge compatibility of the charge transport material and the binder resin is adjusted by setting the amount of the charge transport material to be within the range specified in the present invention. Is considered to be better. If a large amount of the charge transport material is added beyond the range of the amount specified in the present invention, it is easily affected by gas, and adverse effects such as a reduction in the surface resistance of the photoreceptor occur. As a result, image blur, etc. The defect appears. Therefore, not only the kind of the charge transport material to be added but also the addition amount thereof is considered to be in the appropriate range in the range defined in the present application in the compatibility with the hardness of the binder resin of the general formula (1).

In addition, in both the multilayer type photoreceptor and the single layer type photoreceptor, the film forming property, flexibility, coating property, stain resistance, gas resistance, light resistance, etc. are improved for the photosensitive layer or each layer constituting the photosensitive layer. For the purpose, a known antioxidant, plasticizer, ultraviolet absorber, electron-withdrawing compound, leveling agent, visible light shielding agent and the like may be contained.
<Elastic deformation rate>
From the viewpoints of suppressing the generation of scratches on the surface due to friction with the cleaning blade, preventing toner cleaning failure, and suppressing filming, it is preferable that the photosensitive layer has a high elastic deformation rate. The elastic deformation rate depends on both the charge transporting material and the binder resin, and is also affected by the compatibility thereof, so that it is necessary to design the elastic deformation rate so as to be within a suitable range for the combination of materials. The lower limit of the elastic deformation rate of the photosensitive layer is usually 38% or more, preferably 40% or more, more preferably 42% or more, and still more preferably 44% or more, from the viewpoint of preventing poor cleaning. The upper limit is usually 60% or less, preferably 55% or less.
The elastic deformation rate in the present invention is a micro hardness tester FISCHERSCOPE manufactured by Fischer.
It is a value measured using H100C (or an equivalent machine, HM2000) 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. 3 plotted on the Y axis and the X axis are obtained.
・ Measurement conditions Maximum indentation load 5mN
Load required time 10 seconds Unloading required time 10 seconds The above elastic deformation rate is a value defined by the following formula, and the work performed by the film due to elasticity at the time of unloading with respect to the total work required for indentation. It is a ratio.

Elastic deformation rate (%) = (We / Wt) × 100
In the above formula, the total work Wt (nJ) indicates the area surrounded by A-B-D-A in FIG. 2, and the elastic deformation work We (nJ) is the area surrounded by C-B-D-C. Indicates. As the elastic deformation rate is larger, the deformation with respect to the load is less likely to remain, and when the elastic deformation rate is 100, it means that no deformation remains.

<Other functional layers>
In a laminated or single layer type photoreceptor, a protective layer is provided on the outermost layer for the purpose of preventing the photosensitive layer from being worn and preventing or reducing the deterioration of the photosensitive layer due to discharge substances generated from a charger or the like. May be. The protective layer is formed by containing a conductive material in an appropriate binder resin, or charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 and JP-A-10-252377. The copolymer using the compound which has can be used.

Examples of the conductive material used for the protective layer include aromatic amino compounds such as TPD (N, N′-diphenyl-N, N′-bis- (m-tolyl) benzidine), antimony oxide, indium oxide, tin oxide, and oxide. Metal oxides such as titanium, tin oxide-antimony oxide, aluminum oxide, and zinc oxide can be used, but are not limited thereto.
As the binder resin used for the protective layer, known resins such as polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, and siloxane resin can be used. Further, a copolymer of the above resin with a skeleton having a charge transporting ability such as a triphenylamine skeleton as described in JP-A-9-190004 can also be used.

The electrical resistance of the protective layer is usually in the range of 10 ⁹ Ω · cm to 10 ¹⁴ Ω · cm. When the electric resistance is higher than the range, the residual potential is increased, resulting in an image with much fogging. On the other hand, when the electric resistance is lower than the range, the image is blurred and the resolution is reduced. Further, the protective layer must be configured so as not to substantially prevent transmission of light irradiated during image exposure.
Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of a fluororesin, silicone resin, polyethylene resin, or the like. You may contain the particle | grains which consist of these resin, and the particle | grains of an inorganic compound. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer.

<Method for forming each layer>
Each layer constituting the above-described photoreceptor is formed by dip coating, spray coating, nozzle coating, bar coating, roll coating, blade coating on a conductive support obtained by dissolving or dispersing a substance to be contained in a solvent. It is formed by repeating a coating / drying step sequentially for each layer by a known method such as coating.

The coating liquid of the present invention usually contains a solvent. The polyester resin and the charge transport material according to the present invention are present in a state of being dissolved or dispersed in a solvent in the coating liquid of the present invention. Among them, the polyarylate resin and the charge transport material according to the present invention are preferably present in a state dissolved in a solvent.
There is no restriction | limiting in particular in the kind of solvent, In the range which does not impair the effect of this invention remarkably, if the polyarylate resin concerning this invention and a charge transport material are dissolved or disperse | distributed, arbitrary things can be used. For example, alcohols such as methanol, ethanol, propanol and 2-methoxyethanol; ethers such as tetrahydrofuran, 1,4-dioxane and dimethoxyethane; esters such as methyl formate and ethyl acetate; ketones such as acetone, methyl ethyl ketone and cyclohexanone Aromatic hydrocarbons such as benzene, toluene, xylene; dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane , Chlorinated hydrocarbons such as trichloroethylene; nitrogen-containing compounds such as n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine, triethylenediamine; acetonitrile, N-methyl Rupiroridon, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like.

In addition, a solvent may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
Moreover, when using a solvent, there is no restriction | limiting in the usage-amount. However, the solid content concentration of the single-layer coating solution and the multilayer charge transport layer coating solution is usually 10% by weight or more, preferably 15% by weight or more, and usually 40% by weight or less, preferably 35% by weight or less. It is desirable to adjust the amount of solvent used so that it falls within the range. In order to keep the coating property of the coating solution good, the viscosity of the coating solution of the present invention is usually 50 mPa · s or more, preferably 100 mPa · s or more, and usually 1000 mPa · s or less, preferably 600 mPa · s. It is desirable to adjust the composition and use amount of the solvent so as to be in the following range.

  Further, in the case of the charge generation layer of the 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. In addition, the viscosity of the coating solution is usually 0.01 mPa · s or higher, preferably 0.1 mPa · s or higher, and usually 20 mPa · s or lower, preferably 10 mPa · s or lower, at the temperature during use.

Each layer constituting these photoconductors is formed by applying the coating solution obtained by the above-described method on a support using a known coating method, repeating the coating and drying steps for each layer, and sequentially coating the layers. The 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.

The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. Further, the heating temperature may be constant, or heating may be performed while changing the temperature during drying.
<Stability of coating solution>
The coating liquid of the present invention has stable electrical characteristics over time. That is, it is possible to manufacture a photoreceptor having (maintaining) suitable electrical characteristics, whether it is a new coating liquid immediately after manufacturing or an old coating liquid after the time has elapsed after manufacturing.

  Further, the coating liquid of the present invention is stable in liquidity over time. That is, even if time elapses, changes in the state of the liquid due to generation of precipitates and gels, changes in the viscosity of the liquid, and the like hardly occur. The liquidity of the coating liquid can be confirmed by visual observation because the liquid becomes cloudy when precipitates or the like are generated, and can be said to be stable over time when no cloudiness is generated. Further, when the change in viscosity is measured and the change in viscosity is small (for example, when the rate of change in viscosity after 3 months is 10% or less), it can be said that the change is stable over time.

In addition, by forming a photosensitive layer using the coating solution of the present invention, a photoreceptor having a photosensitive layer excellent in electrical characteristics and mechanical strength can be obtained.
<Effect>
As described above, by containing the polyarylate resin according to the present invention in the photosensitive layer and containing a specific amount or less of the charge transport material according to the present invention, a photosensitive layer having excellent electrical characteristics and mechanical strength can be obtained. Can do.

<Image forming apparatus>
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (an image forming apparatus 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 photoreceptor 1, a charging device (charging means) 2, an exposure device (exposure means; image exposure means) 3, and a developing device (developing means) 4. Furthermore, a transfer device (transfer means) 5, a cleaning device (cleaning means) 6, and a fixing device (fixing means) 7 are provided as necessary.
The electrophotographic photosensitive member 1 is not particularly limited as long as it is the above-described electrophotographic photosensitive member. In FIG. 1, as an example, a drum-shaped photosensitive member in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. Showing the body. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged along the outer peripheral surface of the electrophotographic photoreceptor 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, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but other corona charging devices such as corotron and scorotron, and contact-type charging devices such as charging brushes are often used.
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, appropriately referred to as a photosensitive cartridge). For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of exposure apparatus 3 is not particularly limited as long as it can form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member 1 by performing exposure (image exposure) on the electrophotographic photosensitive member 1. Absent. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, and LEDs (light emitting diodes). Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure is performed with monochromatic light having a wavelength of 700 nm to 850 nm, monochromatic light having a wavelength of 600 nm to 700 nm, slightly short wavelength, or monochromatic light having a wavelength of 300 nm to 500 nm. Just do it.

  In particular, in the case of an electrophotographic photoreceptor using a phthalocyanine compound as a charge generating substance, it is preferable to use monochromatic light having a wavelength of 700 nm to 850 nm, and in the case of an electrophotographic photoreceptor using an azo compound, white light or wavelength It is preferable to use monochromatic light of 700 nm or less. The photoreceptor according to the present invention preferably uses monochromatic light having a wavelength of 380 nm to 500 nm as a light source for light input.

  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 silicone 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 silicone resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such 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 (general blade linear pressure is 0.05 to 5 N / 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 polymerized toner is used, the diameter is 4 to 8 μm.
A toner having a small particle size of about m is preferable, and the toner particles can be used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. 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 a toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium, transfer target). Transfer to P.

  There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner. However, when there is little or almost no toner remaining on the surface of the photoreceptor, the cleaning device 6 may be omitted.

  The fixing device 7 includes an upper fixing member (pressure 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. Each of the upper and lower fixing members 71 and 72 includes a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, and a fixing sheet. A member can be used. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve 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 have a configuration capable of performing, 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 a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.
The photosensitive member 1 is combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge (electrophotography). The electrophotographic photosensitive member cartridge may be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. For example, at least one of the charging device 2, the exposure device 3, the developing device 4, and the transfer device 5 can be integrally supported together with the photoreceptor 1 to form a cartridge. Also in this case, similarly to the cartridge described in the above embodiment, when the electrophotographic photosensitive member 1 and other members deteriorate, for example, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic image is obtained. By attaching the photosensitive cartridge to the image forming apparatus main body, maintenance and management of the image forming apparatus are facilitated.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the following examples are given for the purpose of illustrating the present invention in detail, and the present invention is not limited to the examples shown below unless it is significantly contrary to the gist thereof. In the following examples and comparative examples, “parts” indicates “parts by weight” unless otherwise specified.
<Measurement method of viscosity average molecular weight>
First, measurement of the viscosity average molecular weight of the resin will be described.

A resin to be measured is dissolved in dichloromethane to prepare a solution having a concentration C of 6.00 g / L. The flow time t of the sample solution is measured in a constant temperature water bath set at 20.0 ° C. using an Ubbelohde capillary viscometer with a flow time t0 of the solvent (dichloromethane) of 136.16 seconds. The viscosity average molecular weight Mv is calculated according to the following formula.
a = 0.438 × ηsp + 1 ηsp = (t / t0) −1
b = 100 × ηsp / C C = 6.00
η = b / a
Mv = 3207 × η1.205
<Manufacture of photoreceptor sheet>
[Example 1]
High-speed fluidized mixing of rutile type titanium oxide (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) having an average primary particle size of 40 nm and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide. A surface-treated titanium oxide obtained by mixing in a kneading machine (“SMG300” manufactured by Kawata Corporation) and mixing at a high speed at a rotational peripheral speed of 34.5 m / sec was mixed with a ball mill in a mixed solvent of methanol / 1-propanol. Dispersion slurry of hydrophobized titanium oxide was obtained by dispersing. The dispersion slurry, 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 (B Compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [in the following formula (E) After the polyamide pellets are dissolved by stirring and mixing the pellets of the copolymerized polyamide having a composition molar ratio of 60% / 15% / 5% / 15% / 5%, By performing sonic dispersion treatment, the weight ratio of methanol / 1-propanol / toluene is 7/1/2, and hydrophobic treated titanium oxide / copolymerized polyamide is Containing a ratio 3/1, and a solid concentration of 18.0% of the undercoat layer dispersion.

The undercoat layer-forming dispersion thus obtained was applied onto a polyethylene terephthalate sheet having aluminum deposited on the surface with a wire bar so that the film thickness after drying was 1.2 μm, and dried to form an undercoat layer. Provided.
Next, 10 parts of oxytitanium phthalocyanine having a powder X-ray diffraction spectrum shown in FIG. 2 is shown in 1,2-dimethoxyethane as a strong diffraction peak with a Bragg angle (2θ ± 0.2) of 27.3 ° in X-ray diffraction by CuKα ray. In addition to 150 parts, a pigment dispersion was prepared by grinding and dispersing with a sand grind mill. 160 parts of the pigment dispersion thus obtained were added to 100 parts of a 5 wt% 1,2-dimethoxyethane solution of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name # 6000C) and an appropriate amount of 1,2-dimethoxyethane. In addition, a dispersion for forming a charge generation layer having a solid content concentration of 4.0% by weight was finally prepared.

This dispersion was applied onto the above undercoat layer with a wire bar so that the film thickness after drying was 0.4 μm, and then dried to form a charge generation layer.
Next, 100 parts of a polyarylate resin (viscosity average molecular weight: 27,200) represented by the following formula (binder 1), 30 parts of a charge transport material represented by the following formula (CT1), and 0.05 parts of silicone oil as a leveling agent Was dissolved in 640 parts of a dichloroethane solvent to prepare a charge transport layer forming coating solution (photosensitive layer forming coating solution) A.

This charge transport layer forming coating solution A is applied on the above-described charge generation layer using an applicator so that the film thickness after drying is 20 μm, and dried at 125 ° C. for 20 minutes to form a charge transport layer. And
Photoconductor sheet A1 was produced.
[Comparative Example 1]
A photoconductor sheet R1 was obtained in the same manner as in Example 1 except that the binder resin of the charge transport layer was replaced with the binder 2 (viscosity average molecular weight: 29,800) of the following structural formula.

[Comparative Example 2]
In Example 1, the same procedure was followed except that the binder resin of the charge transport layer was changed to binder 3 (viscosity average molecular weight: 35,600) of the following structural formula, and the solvent was changed to THF to obtain a photoreceptor sheet R2.

[Example 2]
In Example 1, instead of the charge transport material CT1, everything was performed in the same manner as in Example 1 except that 20 parts of CT2 having the following structural formula was used to obtain a charge transport layer forming coating solution B and a photoreceptor sheet B1. It was.

[Example 3]
In Example 1, the charge transporting material was changed to CT3 of the following structural formula, and everything was carried out in the same manner as in Example 1 except that the amount added was 40 parts, and the charge transporting layer forming coating solution C and the photoreceptor sheet C1 were used. Got.

[Example 4]
In Example 1, except that the charge transport material was changed to CT4 having the following structural formula, the same procedure as in Example 1 was performed to obtain a charge transport layer forming coating solution D and a photoreceptor sheet D1.

[Example 5]
In Example 1, except that the charge transport material is CT5 of the following structural formula and the number of added parts is changed to 40 parts, the same procedure as in Example 1 is carried out to obtain the charge transport layer forming coating solution E and the photoreceptor sheet E1. Obtained.

[Comparative Example 3]
In Example 5, everything was carried out in the same manner as in Example 5 except that 60 parts of the charge transporting material was changed to obtain a charge transporting layer forming coating solution F and a photoreceptor sheet F1.
Next, in order to examine the stability of the coating solution, the coating solutions E and F for forming a charge transport layer were stored at room temperature for 2 months. Although no change was observed in the coating liquid E, precipitates that were considered to be charge transport materials were confirmed in the coating liquid F.

[Evaluation]
The produced photoreceptor sheets A1 to E1 and R1 to R2 were subjected to the following electrical property test and wear test, and only the electrical property test was conducted on the photoreceptor sheet F1. These results are summarized in Table 2.
<Electrical characteristics test>
Using an electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405), the photosensitive sheet is 80 mm in diameter. Affixed to an aluminum drum to form a cylinder, and the aluminum drum and the aluminum substrate of the photosensitive sheet are connected to each other. Then, the drum is rotated at a constant rotational speed of 60 rpm to perform charging, exposure, potential measurement, and static elimination cycle. An electrical property evaluation test was conducted. At that time, the surface potential after exposure when the initial surface potential of the photosensitive member is charged to −700 VV and the light of the halogen lamp is 780 nm monochromatic light with an interference filter is exposed at 0.8 μJ / cm ² ( Hereinafter, it may be referred to as VL). In the VL measurement, the time required from the exposure to the potential measurement was set to 100 ms, and a fast response condition was set. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%.

<Abrasion test>
The photoreceptor sheet was cut into a circle having a diameter of 10 cm, and the wear was evaluated by a Taber abrasion tester (manufactured by Taber). Test conditions were 23 ° C, 50% RH atmosphere, wear wheel CS-10F (type-III), no load (wear wheel's own weight). Measured by comparison.

[Surface characteristics of photoconductor]
The coating solution for forming a charge transport layer prepared in Example 1, Comparative Example 1 and Comparative Example 2 was applied on a glass plate so that the film thickness after drying was 20 μm, and FischerSCOPE H100C made by Fischer was used. The elastic deformation rate was measured in an environment of a temperature of 25 ° C. and a relative humidity of 50%. The results are shown in Table 3 below.

By using a photosensitive layer having a high elastic deformation rate as shown in Table 3 above, the cleaning performance by the cleaning blade is good, and problems such as toner filming and scratches are hardly generated on the surface, and the surface quality is good. An electrophotographic photoreceptor can be obtained.
Next, evaluation with a drum-shaped photoreceptor was performed.
Example 8
The surface of a cylinder made of an aluminum alloy having an outer diameter of 30 mm, a length of 375.8 mm and a wall thickness of 1.0 mm, which has a mirror-finished surface, is anodized and then sealed with a sealing agent mainly composed of nickel acetate. By performing the hole treatment, an anodized film (alumite film) of about 6 μm was formed. Next, the charge generation layer coating solution used in Example 1 was dip-coated with an anodized aluminum cylinder, and a charge generation layer was prepared so that the film thickness after drying at room temperature was 0.6 μm. The charge transport layer coating solution used in Example 1 and Comparative Example 1 was similarly dip-coated on the charge generation layer, and the photosensitive drum DR1 having a film thickness after drying of 18 μm (containing the binder resin of the present invention). DR2 (containing the above structural formula binder 2) was obtained.

<Evaluation of actual machine>
The produced photosensitive drum was mounted on a black drum cartridge of a commercially available tandem type color printer (Microline Pro 9800PS-E manufactured by Oki Data Co., Ltd.) compatible with A3 printing, and mounted on the printer.
Specifications of MICROLINE Pro 9800PS-E
・ Four tandems ・ Color 36ppm, Monochrome 40ppm
・ 1200 dpi
・ DC contact roller charging
・ Write by LED
・ With static elimination light
・ Polymerized toner
Next, a personal computer was connected to the printer, a black and white image was input, and the output printout image was confirmed. The initial image was good for both photoconductors. Furthermore, when a printing durability test for continuous printing of 10,000 sheets was performed, the image at the end of the test on the photoconductor DR2 was insufficient in contrast with that on the photoconductor DR1. When the film thickness after removing these photoconductors after printing was measured, DR1 was 15.7 μm and DR2 was 12.1 μm.

  The present invention can be used in any field where an electrophotographic photosensitive member is used, and is particularly suitable for use in an image forming apparatus such as a printer or a copying machine.

1 Electrophotographic photoreceptor 2 Charging device (charging roller)
DESCRIPTION OF SYMBOLS 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (pressure roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper

Claims (5)

In an electrophotographic photosensitive member having a photosensitive layer on a conductive support, the photosensitive layer contains a polyarylate resin containing a repeating structure represented by the following general formula (1) as a binder resin, and the photosensitive layer contains An electrophotographic photosensitive member comprising 10 to 45 parts by weight of a charge transport material with respect to 100 parts by weight of a binder resin.

The energy level E_homo of HOMO obtained as a result of the structural optimization calculation by density functional calculation B3LYP / 6-31G (d, p) of the charge transport material is
E_homo> -4.72 (eV)
The electrophotographic photosensitive member according to claim 1, wherein: The calculated value αcal of the polarizability α by the restricted Hartree-Fock method (basic function is 6-31G (d, p)) in the stable structure obtained after the structure optimization calculation by B3LYP / 6-31G (d, p) However, the following formula αcal> 60 (Å ³ )
The electrophotographic photosensitive member according to claim 1, wherein:   An electrophotographic photosensitive member cartridge for an image forming apparatus using the electrophotographic photosensitive member according to claim 1 as an electrostatic latent image carrier.   An image forming apparatus using the electrophotographic photosensitive member according to claim 1 as an electrostatic latent image carrier.

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