JP2001265022A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having very high photosensitivity and low residual potential, nearly free of the accumulation of residual potential even after repeated use, having such very good stability as to suppress the variation of its electrification ability and sensitivity and excellent in durability. SOLUTION: In the electrophotographic photoreceptor with at least a photosensitive layer on an electrically conductive substrate, a polyester resin having a biphenyl structure and a bisphenol structure of formula (1) (where each of A and B is a benzene ring having at least two substituents and X is a divalent organic residue) as repeating units is contained in the photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member. More specifically, the present invention relates to a higher sensitivity and higher performance electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Electrophotographic technology is widely used not only in conventional copying machines but also in various printers and facsimile machines because of its immediacy and high-quality images. At present, some inorganic photoconductive materials such as amorphous silicon and arsenic-selenium are used for photoconductors which form the core of electrophotographic technology, but the mainstream is organic photoconductors.

Several layer configurations have been devised for the organic photoreceptor. The so-called laminated type photoreceptor, in which the functions of charge generation and charge transport are separated and the charge generation layer and the charge transport layer are laminated, has been designed. It has been studied and developed energetically because it is easy to do, has high productivity, and can obtain higher-performance photoconductors. At present, it has been used in medium- and high-speed copiers and printers.

[0004] However, for use in high-speed machines, in terms of electrical characteristics, the photosensitivity is insufficient, the residual potential is high, the photoresponsiveness is poor, and the chargeability decreases when used repeatedly. There are various problems such as accumulation, fluctuation in sensitivity, and deterioration of various characteristics when used at low temperatures, and it cannot be said that the film has sufficient characteristics.

Among them, the development of a higher-performance photoconductor is widely desired for use in high-speed copying machines, printers, and the like. For example, in the case of a photoreceptor in which a charge transport layer composed of a charge transport agent and a binder resin is disposed on an upper layer, toner adheres to the surface of the charge transport layer, and the developer or transfer paper and the photoreceptor surface contact each other. There are problems such as abrasion due to contact, generation of scratches, etc., and many examples of using polycarbonate resin, polymethyl methacrylate resin, etc. as a binder resin in the charge transport layer have been reported to improve these problems. However, there were still problems in electrophotographic characteristics and durability.

Accordingly, various photoconductors using a polyester resin have been reported as an improvement. However, Japanese Patent Application Laid-Open Nos. 62-135840 and 63-2
JP-A-569691, JP-A-3-6567, JP-A-4-274434, JP-A-6-27692, JP-A-9-22126, and JP-A-10-205
No. 17, JP-A-10-268535, and the like have the drawback that the electrical characteristics are significantly deteriorated when used at low temperatures.

Further, the photoreceptor using a polyester resin exemplified in JP-A-5-341439, JP-A-7-114191, JP-A-8-110646, and the like is inferior in ozone resistance. Had.

[0008]

SUMMARY OF THE INVENTION We have been intensively studying a photoreceptor having excellent printing durability and have been studying the use of a polyester resin as a binder resin for a photosensitive layer. It is inevitable that the mobility is deteriorated as compared with the case where is used as a binder, and improvement of the electric characteristics at low temperatures has been a particular problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrophotographic photoreceptor having favorable electrical characteristics and excellent electrical and mechanical properties.
That is, one of the objects of the present invention is to provide an electrophotographic photosensitive member having high mechanical durability such as friction resistance and toner filming property. A second object of the present invention is to provide an electrophotographic photosensitive member having good electric characteristics even at a low temperature.

A third object of the present invention is to provide an electrophotographic photoreceptor which does not cause deterioration over time in chargeability, sensitivity and the like. A fourth object of the present invention is to provide an electrophotographic photoreceptor that satisfies both electrical durability such as charging property and sensitivity and mechanical durability such as friction resistance and toner filming property.

[0011]

Means for Solving the Problems As a result of intensive studies on the binder resin used in the photosensitive layer, the present inventors have found that when a polyester resin having a specific structure is used, excellent electrophotographic properties are exhibited. And completed the present invention. That is, the gist of the present invention is to provide an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, wherein the photosensitive layer has a biphenyl structure as a repeating unit and a bisphenol structure represented by the following general formula (1). An electrophotographic photoreceptor characterized by containing a polyester resin.

[0012]

Embedded image (In the general formula (1), A and B each represent a benzene ring having at least two substituents, and X represents a divalent organic residue.)

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION <Conductive Support> The electrophotographic photosensitive member of the present invention has a structure in which at least a photosensitive layer is provided on a conductive support. As the conductive support on which the photosensitive layer is formed, any of those used for known electrophotographic photosensitive members can be used.

Specifically, for example, a drum or sheet made of a metal material such as aluminum, stainless steel, copper, nickel or the like, or a laminate or a deposit of these metal foils, or aluminum, copper, palladium, tin oxide, oxidized Examples thereof include an insulating support such as a polyester film and paper provided with a conductive layer such as indium. Furthermore, a conductive film such as a metal powder, carbon black, copper iodide, and a polymer electrolyte coated with an appropriate binder and subjected to conductive treatment, a plastic drum,
Paper, paper tube, and the like are included. Further, a plastic sheet or drum containing a conductive substance such as a metal powder, carbon black, or carbon fiber to become conductive may be used. or,
Plastic films and belts that have been subjected to conductive treatment with a conductive metal oxide such as tin oxide and indium oxide can be used.

Among them, an endless pipe made of a metal such as aluminum is a preferable support. A known barrier layer, which is generally used, may be provided between the conductive support and the photosensitive layer. As the barrier layer, for example, an anodized aluminum film, an inorganic layer such as aluminum oxide and aluminum hydroxide, an organic layer such as polyvinyl alcohol, casein, polyvinylpyrrolidone, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, and polyamide. Is used.

When the organic layer is used as the barrier layer, it may be used alone or by dispersing a metal oxide such as titania, alumina, silica and zirconium oxide or a fine metal powder such as copper, silver and aluminum. The thickness of these barrier layers can be set as appropriate, but is usually 0.05 to 2
It is in the range of 0 μm, preferably 0.1 to 10 μm. <Photosensitive Layer> (1) Layer Configuration The photosensitive layer (photoconductive layer) is a layer in which a charge generation layer and a charge transport layer are laminated in this order, or a layer in which a charge generation layer and a charge transport layer are laminated in reverse order, Any of a so-called dispersion type in which a charge generating substance is dispersed in a transport medium can be used.

Specifically, a charge generation material is directly deposited or coated as a dispersion with a binder to form a charge generation layer, and a charge transport material is dissolved together with polyester on the charge generation layer, and the dispersion is applied. To form a charge transport layer (described above), a charge generation layer and a charge transport layer having a reverse stacking order (described above), or a charge generation material and a charge transport material. May be a single-layer type photoreceptor (described above) coated on a conductive support in a state of being dispersed and dissolved in a binder. (2) Binder resin The polyester resin used in the photosensitive layer of the electrophotographic photoreceptor according to the present invention has a biphenyl structure as a repeating unit and a bisphenol structure represented by the following general formula (1).

[0018]

Embedded image (In the general formula (1), A and B each represent a benzene ring having at least two substituents, and X represents a divalent organic residue.) Among them, A and B each represent 2
It is preferable that the compound has two methyl groups, and X is preferably a methylene group.

The polyester resin is obtained by reacting an acid component and a glycol component according to a conventional method.
The biphenyl structure may be contained in any of the acid component and the glycol component, but is preferably contained in the acid component. The viscosity average molecular weight of the polyester resin is usually about 5,000 to 100,000. In consideration of printing durability, the biphenyl structure is preferably, for example, a structure represented by the following general formula (2).

[0020]

Embedded image In consideration of the polymerizability and the like, a more preferred biphenyl structure is a structure represented by the following general formula (3).

[0021]

Embedded image It is. Here, in the general formulas (2) and (3), C and D represent a benzene ring which may have a substituent.

The polyester resin preferably further has a structure represented by the general formula (6) from the viewpoint of solubility and the like.

[0023]

Embedded image (In the general formula (6), E, F and G each represent a benzene ring which may have a substituent. R ₁ and R ₂ each represent a hydrogen atom or an alkyl which may have a substituent. And the polyester resin has structural units represented by the following general formulas (4) and (5), and the numbers of the structural units are x and y, respectively. It is preferable that the ratio of these structural units is represented by the following formula (1) from the viewpoint of the stability of the coating solution.

[0024]

Embedded image

[0025]

Embedded image

[0026]

## EQU4 ## 0.01 <x / (x + y) <0.95 Further, from the viewpoint of electrical characteristics, the above range is

[0027]

It is more preferable that 0.3 <x / (x + y) <0.95,

[0028]

It is most preferable that 0.4 <x / (x + y) <0.90. Further, in consideration of surface properties and printing durability, it is preferable that at least one of each of the benzene rings C and D has a substituent. At this time, the substituent is preferably an alkyl group, and among them, a methyl group is most preferable. In consideration of slipperiness, it is preferable that one benzene ring has two or more substituents.

The main specific examples of the polyester satisfying the above conditions are shown below, but the present invention is not limited thereto.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

[0035]

[Table 6] In addition, BP-1 to BP-
When the polyester of No. 32 is used as a copolymer with each of the polyesters described below, a favorable effect in terms of solubility can be obtained.

[0036]

[Table 7]

[0037]

[Table 8]

[0038]

[Table 9]

[0039]

[Table 10]

[0040]

[Table 11]

[0041]

[Table 12]

[0042]

[Table 13]

[0043]

[Table 14]

[0044]

[Table 15]

[0045]

[Table 16]

[0046]

[Table 17]

[0047]

[Table 18]

[0048]

[Table 19]

[0049]

[Table 20]

[0050]

[Table 21]

[0051]

[Table 22]

[0052]

[Table 23] Examples of the combination of copolymerization include the following examples.

[0053]

[Table 24] (3) Charge transport material In the present invention, the charge transport material used in the photosensitive layer includes:
Any known substances can be used, but the ionization potential IP of the charge transport material is

[0054]

[Mathematical formula-see original document] In a range of 4.7 (eV) <IP <5.5 (eV), it is preferable in terms of electrical characteristics. Further, it is preferable that the charge transport material contains a charge transport material having at least one of a stilbene skeleton, an arylamine skeleton, and a butadiene skeleton in its structural formula.

Next, main specific examples of the charge transporting material satisfying the above conditions will be shown, but the present invention is not limited thereto.

[0056]

[Table 25]

[0057]

[Table 26]

[0058]

[Table 27]

[0059]

[Table 28]

[0060]

[Table 29]

[0061]

[Table 30]

[0062]

[Table 31]

[0063]

[Table 32]

[0064]

[Table 33]

[0065]

[Table 34]

(4) Charge Generating Substances The charge generating substances include selenium, selenium-tellurium alloy,
Inorganic photoconductive particles such as selenium-arsenic alloy, cadmium sulfide, amorphous silicon, etc .; metal-free phthalocyanine, metal-containing phthalocyanine, perinone pigment, thioindigo, quinacridone, perylene pigment, anthraquinone pigment, azo pigment, bisazo pigment, trisazo Organic photoconductive particles such as pigments, tetrakis azo pigments, and cyanine pigments.

Further, various organic pigments and dyes such as polycyclic quinone, pyrylium salt, thiopyrylium salt, indigo, anthantrone and pyranthrone can be used. Among them, metal-free phthalocyanine, copper, indium chloride, gallium chloride,
Metals such as tin, oxytitanium, zinc, vanadium, or their oxides, phthalocyanines coordinated with chlorides,
Azo pigments such as monoazo, bisazo, trisazo and polyazos are preferred.

Preferred azo components of the azo pigment include the following structures.

[0069]

Embedded image Preferred coupling components for the diazo component include the following structures.

[0070]

Embedded image These azo components and couplers may have a substituent. As azo pigments, JP-A-54-79632;
JP-A-54-145142, JP-A-55-11715
No. 1, JP-A-57-176055, JP-A-63-19
The use of bisazo pigments disclosed in JP-A Nos. 2627 and 63-282743 is preferable from the viewpoint of electrical characteristics.

Further, a metal-containing and metal-free phthalocyanine is used as the charge generating material, and
By combining the binder resin represented by the formula (1), a photoconductor having improved sensitivity to laser light can be obtained. In particular, when the photosensitive layer contains at least a charge generating material and a charge transporting material, the charge generating material has an oxy group having a diffraction peak at a black angle (2θ ± 0.2 °) of 27.3 ° in the X-ray diffraction spectrum. Titanium phthalocyanine or (2θ
Oxytitanium phthalocyanine showing diffraction peaks at 9.3 °, 13.2 °, 26.2 °, and 27.1 °, Bragg angle 2θ (± 0.3 °) 9.2, 14.1, 15.
Dihydroxysilicon phthalocyanine compound having diffraction peaks at 3, 19.7 and 27.1 °, X-ray diffraction spectrum black angle (2θ ± 0.2 °) 8.5 °, 12.2 °, 1
It is preferable to contain dichlorotin phthalocyanine showing main diffraction peaks at 3.8 °, 16.9 °, 22.4 °, 28.4 ° and 30.1 °. (5) Other Additives-Dye Colorant In the present invention, the dye colorant optionally added to the photosensitive layer includes, for example, triphenylmethane dyes such as methyl violet, brilliant green and crystal violet, thiazine dyes such as methylene blue, and quinizarin Such as quinone dyes and cyanine dyes and billium salts,
Thiavirylium salts, benzovirylium salts and the like can be mentioned. -Electron-withdrawing compound In the present invention, examples of the electron-withdrawing compound optionally added to the photosensitive layer include chloranil, 2,3-dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5- Quinones such as nitroanthraquinone, 2-chloroanthraquinone and phenanthrenequinone; aldehydes such as 4-nitrobenzaldehyde; 9
-Benzoylanthracene, indandione, 3,5-
Ketones such as dinitrobenzophenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 3,3 ', 5,5'-tetranitrobenzophenone; phthalic anhydride, 4-chloronaphthal Acid anhydrides such as acid anhydrides; tetracyanoethylene, terephthalalmalononitrile, 9-anthrylmethylidenemalononitrile, 4-nitrobenzalmalononitrile, 4- (p
-Nitrobenzoyloxy) cyano compounds such as benzalmalononitrile; 3-benzalphthalide, 3- (α-cyano-p-nitrobenzal) phthalide, 3- (α-cyano-p-nitrobenzal) -4,5,6,7 -Electron-withdrawing compounds such as phthalides such as tetrachlorophthalide. <Method of Forming Photosensitive Layer> The photosensitive layer of the electrophotographic photoreceptor of the present invention may contain a well-known plasticizer to improve film formability, flexibility, and mechanical strength.

At this time, examples of the plasticizer to be added to the coating solution include phthalic acid esters, phosphate esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and aromatic compounds such as methylnaphthalene. In the case of a laminated photoreceptor, the coating liquid when the arylamine-based compound is used as the charge transporting material in the charge transporting layer may have the above-mentioned composition, but the photoconductive particles, the dye, the electron withdrawing compound, etc. Remove or add a small amount.

In this case, the charge generation layer is formed by dissolving or dispersing the photoconductive particles in a solvent such as a binder polymer or another organic photoconductive substance, a dye or an electron-withdrawing compound, if necessary. Examples include a thin layer formed by applying and drying a liquid, and a layer in which the photoconductive particles are formed into a film by means such as vapor deposition. Examples of the method for coating the photosensitive layer include a spray coating method, a spiral coating method, a ring coating method, and a dip coating method.

As the spray coating method, air spray,
There are airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, hot airless spray, etc., considering the degree of atomization and adhesion efficiency to obtain a uniform film thickness. In the rotary atomization type electrostatic spray, the conveying method disclosed in the re-published Japanese Patent Publication No. 1-805198, that is, by continuously conveying the cylindrical work without rotating the axial direction while rotating the cylindrical work, An electrophotographic photoreceptor excellent in uniformity of film thickness with high overall deposition efficiency can be obtained.

The spiral coating method is disclosed in
Japanese Patent Application Laid-Open No. H11-231966 discloses a method using a liquid injection coating machine or a curtain coating machine disclosed in Japanese Patent Application Publication No. 119651.
There is a method disclosed in Japanese Patent Application Laid-Open Publication No. H10-193, in which the coating material is continuously flew from the minute opening in a streak shape, and a method using a multi-nozzle body disclosed in Japanese Patent Application Laid-Open No. 3-193161.

The dip coating method includes, for example, the following procedure. First, using a charge transporting substance (preferably the above-mentioned compound), a binder, a solvent, or the like, a suitable total solid content concentration is 25% or more, and more preferably 40% or more.
% Or less and the viscosity is usually 50 centipoise to 300
A coating liquid for forming a charge transporting layer having a density of not more than centipoise, preferably 100 to 200 centipoise is prepared.

Here, the viscosity of the coating solution is substantially determined by the type of the binder polymer and its molecular weight. If the molecular weight is too low, the mechanical strength of the polymer itself is reduced, so that the molecular weight of the polymer does not deteriorate. It is preferable to use a binder polymer having the same. The charge transport layer is formed by a dip coating method using the coating solution thus adjusted.

Thereafter, the coating film is dried, and the drying temperature and time are preferably adjusted so that necessary and sufficient drying is performed. The drying temperature is usually 100 to 250 ° C, preferably 110 to 250 ° C.
170 ° C, more preferably in the range of 120 to 140 ° C. As a drying method, hot air dryer, steam dryer,
An infrared dryer and a far infrared dryer can be used.

The thus obtained electrophotographic photoreceptor of the present invention has high sensitivity, low residual potential, high chargeability, and small fluctuation due to repetition. In particular, the charge stability affecting image density is low. Since it is good, it can be used as a highly durable photoconductor. Further, since the sensitivity is high in the range of 750 to 850 nm, it is particularly suitable for a photoreceptor for a semiconductor laser printer. <Laminated Photoreceptor>-Charge Generating Layer The charge generating layer forming the above-mentioned laminated photoconductive layer is composed of a binder resin and another organic photoconductive compound, a dye, an electron if necessary. It is dissolved or dispersed in a solvent together with a suction compound or the like, and the coating liquid thus obtained is applied and dried to obtain a charge generation layer.

That is, the charge generation layer in the layered photosensitive layer is made of fine particles of these substances, for example, polyester resin, polyvinyl acetate, polyester, polycarbonate, polyvinyl acetoacetal, polyvinyl propional, polyvinyl butyral, phenoxy resin,
It may be used in a dispersion layer in a form bound with various binder resins such as an epoxy resin, a urethane resin, a cellulose ester and a cellulose ether. Further, examples of the binder resin include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinyl alcohol, and ethyl vinyl ether, polyamide, and silicon resin. In this case, the use ratio of the charge generation material (charge generation substance) is usually 20 to 2 with respect to 100 parts by weight of the binder resin.
000 parts by weight, preferably 30 to 500 parts by weight, more preferably 33 to 500 parts by weight, and the thickness of the charge generation layer is usually 0.05 to 5 μm, preferably 0.1 to 5 μm.
The thickness is preferably from 1 to 2 μm, more preferably from 0.15 to 0.8 μm. Further, the charge generation layer may contain various additives such as a leveling agent, an antioxidant, and a sensitizer for improving applicability, if necessary. Furthermore, the charge generation layer may be a deposited film of the above-described charge generation material. -Charge transport layer As the charge transport material used in the charge transport layer, in addition to the charge transport material having at least one structure selected from stilbene, arylamine, and butadiene skeleton, hydrazone, condensed polycyclic, and heterocyclic A compound having a ring and an enamine skeleton can be used in combination.

As the binder resin used in the charge transport layer, in addition to the above-mentioned polyester resin of the present invention,
For example, vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyester, polyester carbonate, polysulfone, polyimide, phenoxy, epoxy, and silicone resin may be shared or copolymerized. It is also possible to use these partially crosslinked cured products.

The ratio of the binder resin to the charge transporting substance is usually 30 parts by weight with respect to 100 parts by weight of the binder resin.
It is used in an amount of from 90 to 90 parts by weight, preferably from 40 to 70 parts by weight. The thickness of the charge transport layer is usually 10 to 60 μm.
m, preferably 10 to 45 μm, more preferably 27 to 4 μm.
Preferably, it is used at a thickness of 0 μm.

Further, the charge transport layer may contain various additives such as an antioxidant and a sensitizer, and other charge transport materials, if necessary. In addition, various additives for improving the mechanical strength and durability of the coating film can be used. Examples of such additives include well-known plasticizers, various stabilizers, fluidity-imparting agents, and cross-linking agents.・
Formation method of photosensitive layer In the case of a photosensitive layer composed of two layers, a charge generation layer and a charge transport layer, the above-mentioned coating solution is applied on the charge generation layer, or the charge transport layer obtained by applying the above coating solution. It can be manufactured by forming a charge generation layer thereon.

Solvents for preparing a coating solution include ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; N, N-dimethylformamide, acetonitrile; N-methylpyrrolidone,
Aprotic polar solvents such as dimethyl sulfoxide; esters such as ethyl acetate, methyl formate, and methyl cellosolve acetate; solvents that dissolve amine compounds such as chlorinated hydrocarbons such as dichloroethane and chloroform. Of course, it is necessary to select a material that dissolves the binder from these.

The photoreceptor formed as described above may also be provided with an intermediate layer such as a barrier layer, an adhesive layer, and a blocking layer, a transparent insulating layer, or a protective layer, if necessary, to improve electrical and mechanical properties. It is needless to say that a layer may be provided. As the outermost layer, a conventionally known overcoat layer mainly composed of, for example, a thermoplastic or thermosetting polymer may be provided.

As a method for forming each layer, a known method such as sequentially applying a coating solution obtained by dissolving or dispersing a substance to be contained in a layer in a solvent can be applied. <Single-Layer Photoreceptor> In the case of the above-mentioned dispersion type photosensitive layer, the kind of the charge generating substance used is the same as that described above, but the particle diameter thereof needs to be sufficiently small, preferably 1 μm. Below, more preferably, it is used at 0.5 μm or less.

The amount of the charge generating substance dispersed in the photosensitive layer is, for example, in the range of 0.5 to 50% by weight. If the amount is too small, sufficient sensitivity cannot be obtained.
There are adverse effects such as a decrease in sensitivity, and more preferably 1 to 20.
Used in the range of weight percent. The single-layer type photosensitive layer is prepared by dissolving the above-described charge transporting material together with the above-described binder resin in a suitable solvent according to a conventional method, and, if necessary, a suitable charge generating material, a sensitizing dye, an electron-withdrawing compound, Other charge transporting materials, or a coating solution obtained by adding a known additive such as a plasticizer and a pigment onto a conductive support, dried, and usually several μ to several tens μ, preferably 10-45 μm,
Particularly preferably, it can be produced by forming a layer having a thickness of 20 μm or more.

[0088]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist thereof. Example 1 (2θ ± 0.2 °) 9.3 °, 13.2 °, 26.2
200 parts by weight of n-propanol were added to 10 parts by weight of oxytitanium phthalocyanine showing X-ray diffraction peaks at 0 ° and 27.1 ° by CuKα radiation, and the mixture was pulverized with a sand blind mill for 10 hours to perform atomization and dispersion treatment. Next, a dispersion was prepared by mixing 5 parts by weight of polyvinyl butyral (trade name “Denka butyral” # 6000C, manufactured by Denki Kagaku Kogyo KK) with a 10% methanol solution. Next, the dispersion was dried by a bar coater on an aluminum-deposited surface on which a polyester film was deposited to a thickness of 0.4 μm.
The charge generation layer was provided such that On this charge generation layer, 60 parts by weight of the above-described charge transport material (CT-38),
Then, a solution prepared by dissolving 100 parts by weight (Mv = 32100) of a 1: 1 copolymer of the polyesters (BP-1) and (M-1) in 1,000 parts by weight of a tetrahydrofuran / toluene mixed solution is applied by a film applicator. Then, a charge transport layer was provided so that the film thickness after drying was 20 μm.

The obtained photoreceptor is referred to as photoreceptor A. The evaluation of the photoreceptor was performed as follows. [Abrasion Test] Photoconductor A was cut into a circle having a diameter of 10 cm, and abrasion was evaluated using a Taber abrasion tester (manufactured by Toyo Seiki Co., Ltd.). The test conditions were 23 ° C and 50% RH.
Using the worn wheel CS-10F, the amount of wear after 1000 rotations without a load (the weight of the worn wheel) was measured by comparing the weight before and after the test. The results are shown in Table 1.

[Friction Test] The toner was uniformly placed on the photoreceptor prepared above at a concentration of 0.1 mg / cm ^2, and urethane rubber of the same material as that of the cleaning blade was cut to a width of 1 cm on the surface to be contacted. Used at 45 degree angle, load 200g, speed 5mm / sec, stroke 2
The coefficient of kinetic friction when urethane rubber was moved at 0 mm was measured using the fully automatic friction and wear tester DFPM manufactured by Kyowa Interface Chemical Co., Ltd.
-Measured by SS. The results are shown in Table 1.

[Electrical Characteristics] The electrical characteristics at 5 ° C. and a humidity of 10% were determined as follows. The half-exposure amount is obtained by first negatively charging the photoreceptor A with a corona current of 50 μA in a dark place, then exposing the same to light of 780 nm, and measuring the exposure amount required for the surface potential to attenuate from −700 V to −350 V. Determined by In addition, 780 nm light is 2.4 MJ
/ Cm ² and the residual potential (Vr) after irradiation with static elimination light were measured. Table 1 shows the results.
Shown in

[Ionization Potential] The ionization potential of the charge transporting substance (CT-38) powder used for the photoreceptor A was measured using an AC-1 manufactured by Riken Keiki, and was found to be 5.19 eV. . Comparative Example 1 In place of the copolymerized polyester used for the charge transport layer in Example 1, the above-mentioned polyester (P-1) and (M
Comparative Photoconductor 1 was prepared in the same manner as in Example 1 except that the 1: 1 copolymer of -1) was used. Next, in the same manner as in Example 1, the friction coefficient, the wear amount, the sensitivity, the residual potential, and the surface potential were measured. The results are shown in Table 1.

[0093]

[Table 35] As is clear from the above results, the photoreceptor according to the present invention has
It can be seen that the photoconductor shows very good sensitivity and residual potential with respect to the comparative photoconductor. In particular, it has excellent characteristics at low temperature and low humidity. The friction and wear characteristics are also very good.

[0094]

The electrophotographic photoreceptor of the present invention exhibits extremely high photosensitivity and low residual potential, has little accumulation of residual potential even when used repeatedly, and has very little fluctuation in chargeability and sensitivity. Extremely good stability and excellent durability. Further, since the electrical characteristics are not significantly deteriorated even at a low temperature, it can be used for a high-speed copying machine or printer without any problem.

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Yuta Kumano 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Chemical Research Institute (72) Inventor Akiteru Fujii 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Mitsubishi Chemical Corporation Yokohama Research Laboratory (72) Inventor Protection 1000 Kamoshitacho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Mitsubishi Chemical Research Laboratory Yokohama Research Laboratory F-term (reference) 2H068 AA13 AA20 AA33 AA34 AA35 BA12 BA13 BA22 BB26 BB27 BB53 FA01 FA13 FA19

Claims (10)

[Claims] 1. An electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, wherein the polyester resin has a biphenyl structure as a repeating unit and a bisphenol structure represented by the following general formula (1) in the photosensitive layer. An electrophotographic photoreceptor comprising: Embedded image (In the general formula (1), A and B each represent a benzene ring having at least two substituents, and X represents a divalent organic residue.) 2. The electrophotographic photosensitive member according to claim 1, wherein the biphenyl structure is represented by the following general formula (2). Embedded image (In the general formula (2), C and D represent a benzene ring which may have a substituent.) 3. The electrophotographic photoreceptor according to claim 1, wherein the biphenyl structure is represented by the following general formula (3). Embedded image 4. The electrophotographic photoreceptor according to claim 1, wherein in formula (1), A and B each have at least two methyl groups. 5. The electrophotographic photoreceptor according to claim 1, wherein in the general formula (1), X is a methylene group. 6. A polyester resin represented by the following general formula (4):
And a structural unit represented by (5), wherein the numbers of the structural units are x and y, respectively, and the ratio of these structural units is represented by the following formula (1). 5. The electrophotographic photosensitive member according to any one of 5. Embedded image Embedded image [Expression 1] 0.01 <x / (x + y) <0.95 (1) 7. The electrophotographic photoreceptor according to claim 6, wherein the ratio between x and y is represented by the following formula (2). 0.3 <x / (x + y) <0.95 (2) 8. The photosensitive layer on the conductive support contains a charge transporting substance having an ionization potential IP in the range of 4.7 (eV) <IP <5.5 (eV). Item 8. The electrophotographic photosensitive member according to any one of Items 1 to 7. 9. The photosensitive layer according to claim 1, wherein the photosensitive layer on the conductive support contains a charge transport material having at least one structure selected from a stilbene skeleton, an arylamine skeleton, and a butadiene skeleton. The electrophotographic photosensitive member according to the above. 10. The electron according to claim 1, wherein the photosensitive layer comprises at least a charge generation layer and a charge transport layer, and the charge transport layer contains a charge transport agent and a polyester resin. Photoreceptor.