JP6380124B2 - Electrophotographic photoreceptor, image forming apparatus, and polyester resin - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having good wear resistance.

  Since the electrophotographic photosensitive member is repeatedly used in an electrophotographic process, that is, a cycle such as charging, exposure, development, transfer, cleaning, and static elimination, it is deteriorated by various stresses during the process. Such deterioration includes, for example, strongly oxidative ozone generated from a corona charger normally used as a charger, chemical damage caused by NOx to the photosensitive layer, and carrier (current) generated by image exposure. There are chemical and electrical degradations such as decomposition of the photosensitive layer composition caused by flowing inside or static elimination light and external light. Furthermore, there is mechanical deterioration such as abrasion of the photosensitive layer surface due to rubbing of a cleaning blade, a magnetic brush or the like, contact with a developer or paper, generation of scratches, peeling of the film, and the like. Such damage due to mechanical deterioration tends to appear on the image, and directly impairs the image quality, which is a major factor that limits the life of the photoreceptor.

In the case of a general photoreceptor not provided with a functional layer such as a surface protective layer, the photosensitive layer is particularly susceptible to such a load. The photosensitive layer is usually composed of a binder resin and a photoconductive material, and it is the binder resin that substantially determines the strength, but since the amount of the photoconductive material doped is considerably large, sufficient mechanical strength is provided. Has not reached.
In recent years, a polyester resin excellent in sensitivity and wear resistance has been used as a binder resin for a photosensitive layer. (See Patent Documents 1 to 3). Furthermore, it has been reported that the mechanical strength of the photoreceptor is further improved by using diphenyl ether dicarboxylic acid or diphenyl dicarboxylic acid component as the dicarboxylic acid component of the polyester resin (see Patent Documents 4 to 7).

Japanese Patent Laid-Open No. 3-6567 JP-A-9-22126 JP 2004-294750 A Japanese Patent Laid-Open No. 10-20514 JP 2001-265021 A JP 2006-53549 A JP 2008-293006 A

  However, according to the inventor's study, in the photoconductor using the polyester resin of the techniques described in Patent Documents 1 to 7, the mechanical strength is high in a high-life / high-speed high-end model that prints 100,000 sheets or more. Was not enough. In addition, when a resin having a high content of diphenyldicarboxylic acid is used, when a coating solution for forming a photosensitive layer is produced using a non-halogen solvent, precipitation may occur and stability may be lacking.

Moreover, in the said patent document, there is no description of the polyester resin containing both components of diphenyl ether dicarboxylic acid and diphenyl dicarboxylic acid, and the improvement of the mechanical physical property by combining these both components was not considered.
The present invention has been made in view of the above problems. That is, an object of the present invention is to provide an electrophotographic photosensitive member that is excellent in the stability of the coating solution for forming a photosensitive layer even when a non-halogen solvent is used, and that has excellent wear resistance and electrical characteristics against a practical load. That is.

  As a result of intensive studies on an electrophotographic photosensitive member that can solve the above-mentioned problems, the present inventors have excellent mechanical properties by including a polyester resin having a specific chemical structure in the photosensitive layer. Based on this finding, it has been found that an electrophotographic photoreceptor having high solubility and excellent coating solution stability with respect to the solvent used in the coating solution for forming the photosensitive layer can be obtained, and having excellent electrical characteristics. The present invention has been completed.

  That is, the invention according to claim 1 has a conductive support and a photosensitive layer formed on the conductive support, and the photosensitive layer is a divalent carboxylic acid represented by the following formula (1). A polyester resin having a repeating structure of an acid residue, a divalent carboxylic acid residue represented by the following formula (2), and a divalent phenol residue represented by the following formula (3): The divalent carboxylic acid residue amount represented by the following formula (1) and the following formula (2) is 70 mol% or more based on the total carboxylic acid residues, and the divalent compound represented by the formula (1). The electrophotographic photosensitive member is characterized in that the content of the carboxylic acid residue satisfies a relationship of 0.3 ≦ (1) / ((1) + (2)) ≦ 0.9 in terms of molar ratio.

(In the formula ^(1), each R 1, ^{R 2} are independently an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or a benzyl group, n, m is , Represents an integer of 0 to 4.)

(In Formula (2), R < ³ >, R < ⁴ > shows a C1-C10 alkyl group, a C1-C10 alkoxyl group, a halogenated alkyl group, or a benzyl group each independently, p and q are , Represents an integer of 0 to 4.)

(In formula (3), R ^{5 to} R ⁸ are each independently an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a halogenated alkyl group, a benzyl group, or an aryl group, and X ¹ is A single bond, an alkylene group, —CR ⁹ R ¹⁰ —, an oxygen atom, or a sulfur atom, wherein R ⁹ and R ¹⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, or R ^9; And R ¹⁰ are bonded to each other to form a ring that may have a substituent.
In the invention according to claim 2, in the polyester resin, the content of the divalent carboxylic acid residue represented by the formula (1) is 0.5 ≦ (1) / ((1) + ( 2)) The electrophotographic photosensitive member according to claim 1, which satisfies ≦ 0.8.

  In the invention according to claim 3, in the polyester resin, the divalent carboxylic acid residue represented by the formula (1) is represented by the dicarboxylic acid represented by the following formula (4) and the formula (2). The electrophotographic photosensitive member according to claim 1, wherein the divalent carboxylic acid residue is a dicarboxylic acid represented by the following formula (5).

  The invention according to claim 4 is the polyester resin, wherein the divalent phenol residue represented by the formula (3) is a divalent phenol residue represented by the following formula (6). The electrophotographic photosensitive member according to any one of the above.

(In Formula (6), X ² represents a single bond, an alkylene group, or —CR ¹¹ R ¹² —. R ¹¹ and R ¹² each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. .)
The invention according to claim 5 is the electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the photosensitive layer is formed using a coating solution containing a non-halogen solvent.
According to a sixth aspect of the present invention, there is provided an electrophotographic photosensitive member according to any one of the first to fifth aspects, a charging device for charging the electrophotographic photosensitive member, and a static device by exposing the charged electrophotographic photosensitive member. An image forming apparatus comprising: an exposure device that forms an electrostatic latent image; and a developing device that develops an electrostatic latent image formed on the electrophotographic photosensitive member.

  The invention according to claim 7 is a polyester resin having a repeating structure of a divalent carboxylic acid residue and a divalent phenol residue, and a divalent carboxylic acid residue represented by the above formula (1), the above formula (2) And a divalent carboxylic acid residue represented by the above formula (3) and a divalent phenol residue represented by the above formula (3), the divalent carboxylic acid residue represented by the above formula (1) and the above formula (2). And the content of the divalent carboxylic acid residue represented by the formula (1) is 0.3 ≦ 0.3% in terms of molar ratio. It is a polyester resin characterized by satisfying (1) / ((1) + (2)) ≦ 0.9.

  The polyester resin has high solubility in a solvent used in a coating solution for forming a photosensitive layer and excellent coating solution stability, and the photoreceptor of the present invention using the polyester resin has various properties such as wear resistance and electrical characteristics. Excellent properties. Although the reason for the improvement of the wear resistance is not clear, the polyester resin becomes moderately flexible by containing a divalent carboxylic acid residue having an ether bond as in the above formula (1), while the above formula It is thought that the resin chain becomes rigid by containing a divalent carboxylic acid residue as in (2), and the polyester resin can have appropriate rigidity and toughness.

  According to the present invention, it is possible to obtain an electrophotographic photosensitive member that is particularly excellent in wear resistance and excellent in electrical characteristics and adhesion.

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

The best mode for carrying out the present invention (hereinafter, an embodiment of the present invention) will be described in detail below. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.
≪Polyester resin≫
The photosensitive layer of the electrophotographic photoreceptor to which this exemplary embodiment is applied contains a polyester resin having a divalent carboxylic acid residue represented by the following formula (1).

In formula (1), R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or a benzyl group, n, m is an integer of 0-4. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, an isobutyl group, and a cyclohexyl group. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a cyclohexoxy group. Examples of the halogenated alkyl group include a chloromethyl group and a fluorinated alkyl group. From the viewpoint of wear resistance, an alkyl group having 1 to 6 carbon atoms and an alkoxyl group having 1 to 6 carbon atoms are preferable, and a methyl group and an ethyl group are particularly preferable. n and m are each independently an integer of 0 to 4, and preferably n = m = 0 from the viewpoint of simplicity in production.

Specific examples of the divalent carboxylic acid compound that derives the divalent carboxylic acid residue represented by the formula (1) include, for example, diphenyl ether-2,2′-dicarboxylic acid, diphenyl ether-2,4′-dicarboxylic acid, And diphenyl ether-4,4′-dicarboxylic acid. Among these, diphenyl ether-4,4′-dicarboxylic acid is particularly preferable from the viewpoints of production simplicity and wear resistance.
Moreover, the said polyester resin contains the bivalent carboxylic acid residue represented by following formula (2).

In formula (2), R ³ and R ⁴ are each independently an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or a benzyl group, and p and q are It is an integer of 0-4. As the alkyl group, alkoxyl group, and halogenated alkyl group, those exemplified for R ¹ and R ² can be applied. From the viewpoint of wear resistance, an alkyl group having 1 to 6 carbon atoms and an alkoxyl group having 1 to 6 carbon atoms are preferable, and a methyl group and an ethyl group are particularly preferable. From the viewpoint of simplicity in production, p and q are particularly preferably p = q = 0.

Specific examples of the divalent carboxylic acid compound derived from the divalent carboxylic acid residue represented by the formula (2) include, for example, 4,4′-diphenyldicarboxylic acid, 2,2′-diphenyldicarboxylic acid, 2,4 And '-diphenyldicarboxylic acid. Among these, 4,4′-diphenyldicarboxylic acid is particularly preferable from the viewpoint of ease of production and wear resistance.
In the polyester resin, the total content of the divalent carboxylic acid residues represented by the formulas (1) and (2) is 70 mol% or more based on the total divalent carboxylic acid component. From the viewpoint of wear resistance, it is preferably 90 mol% or more.

Moreover, content of the bivalent carboxylic acid residue represented by Formula (1) is 0.3 mol% with respect to the total amount of the divalent carboxylic acid residue represented by Formula (1) and Formula (2). It is 0.9 mol% or less. From the viewpoint of wear resistance and adhesiveness, it is preferably 0.8 mol% or less, more preferably 0.75 mol% or less. Further, from the viewpoint of wear resistance, it is preferably 0.5 mol% or more, more preferably 0.6 mol% or more.
The polyester resin contains a divalent phenol residue represented by the following formula (3).

In formula (3), R ^{5 to} R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a halogenated alkyl group, a benzyl group, or an aryl group, X ¹ represents a single bond, an alkylene group, —CR ⁹ R ¹⁰ —, an oxygen atom, or a sulfur atom. R
⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, or a group that forms a ring in which R ⁹ and R ¹⁰ are bonded to each other and may have a substituent. Show.
As the alkyl group, alkoxyl group, and halogenated alkyl group of R ^{5 to} R ⁸ , those exemplified for R ¹ and R ² can be applied. Specific examples of the aryl group in R ^{5 to} R ⁸ include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a tolyl group, a chlorophenyl group, and a fluorophenyl group. R ^{5 to} R ⁸ are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms from the viewpoint of mechanical properties. From the viewpoint of mechanical properties, a hydrogen atom and a methyl group are particularly preferable.

Specific examples of the alkylene group for X ¹ include — (CH ₂ ) ₂ —, — (CH ₂ ) ₃ — and the like. As the alkyl group and aryl group in R ⁹ and R ¹⁰ , those exemplified for R ^{5 to} R ⁸ can be applied. In R ⁹ and R ^10, specific examples of the groups R ⁹ and R ¹⁰ form a ring which may have a bond to a substituent each other, cyclohexylidene group and the like. In formula (3), X ¹ is preferably —CR ⁹ R ¹⁰ — from the viewpoint of mechanical properties and ease of production. In particular, it is preferred that ^{X 1} is ^{X 2, X 2} is a single bond, an alkylene group, or a ^-CR 11 ^{R 12} - ^indicates, R ^{11, R 12} are each independently a hydrogen atom or 1 to carbon atoms 3 alkyl groups are shown.

  Specifically, bis- (4-hydroxyphenyl) methane, 1,1-bis- (4-hydroxyphenyl) ethane, 2,2-bis- (4-hydroxyphenyl) propane, 2,2-bis- ( 4-hydrokey 3-methylphenyl) propane, bis- (4-hydroxy-3-methylphenyl) methane, 1,1-bis- (4-hydroxyphenyl) cyclohexane, 1,1-bis- (4-hydroxy-3) -Methylphenyl) ethane, bis- (4-hydroxy-3,5-dimethylphenyl) methane, 1,1-bis- (4-hydroxy-3,5-dimethylphenyl) ethane, 2,2-bis- (4 -Hydroxy-3,5-dimethylphenyl) propane, bis- (4-hydroxy-3,6-dimethylphenyl) methane, 1,1-bis- (4-hydroxyphenyl) -1-phenyl ethane, 1,1-bis - (4-hydroxyphenyl) propane. It is also possible to use a combination of a plurality of these dihydric phenol components.

  Among these, bis (4-hydroxyphenyl) methane, 1,1-bis- (4-hydroxyphenyl) ethane, 1,1-bis-(( 4-Hydroxy-3-methylphenyl) ethane, bis- (4-hydroxy-3-methylphenyl) methane, and 2,2-bis- (4-hydroxy-3-methylphenyl) propane are preferred. In consideration of solubility and adhesion, 1,1-bis- (4-hydroxy-3-methylphenyl) ethane and 2,2-bis- (4-hydroxy-3-methylphenyl) propane are particularly preferable.

The viscosity average molecular weight (Mv) of the polyester resin is usually 10,000 or more, and preferably 25,000 or more from the viewpoint of mechanical strength. Further, it is usually 150,000 or less, and preferably 100,000 or less from the viewpoint of applicability.
The carboxylic acid value of the polyester resin is preferably 100 µequivalent / g or less, more preferably 50 µequivalent / g or less. When the carboxylic acid value exceeds 100 µequivalent / g, the electrical characteristics of the photoreceptor tend to deteriorate, and further, the storage stability when the resin is dissolved in a solvent to form a coating solution tends to be lowered. .

  The amount of the free divalent carboxylic acid contained in the polyester resin is not particularly limited, but is preferably 50 ppm or less, and more preferably 10 ppm or less. When the content of the free divalent carboxylic acid exceeds 50 ppm, the electrical characteristics of the photoreceptor may be deteriorated or it may become a foreign substance appearing in image evaluation. The smaller the amount of free divalent carboxylic acid, the better from the viewpoint of the electrical properties and image characteristics of the photoreceptor, but from the viewpoint of the stability of the polyester resin, it is preferably 0.01 ppm or more, and 0.1 ppm or more. It is particularly preferred that

  Furthermore, the amount of the free dihydric phenol contained in the polyester resin is not particularly limited, but is preferably 100 ppm or less, more preferably 50 ppm or less. If it exceeds 100 ppm, foreign matters may be produced depending on the deterioration of electrical characteristics, coloring, and the solvent used. From the viewpoint of the electrical characteristics of the photoreceptor, the less free divalent phenol is better, but from the viewpoint of ease of production, it is preferably 0.001 ppm or more, and particularly preferably 0.01 ppm or more.

  For the photosensitive layer in the electrophotographic photoreceptor to which this exemplary embodiment is applied, the polyester resin and other resins may be mixed and used from the viewpoints of adhesiveness and coatability. Examples of the resin having another structure mixed here include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride and copolymers thereof; polycarbonate resin, polyester resin, polyester polycarbonate resin, polysulfone resin, phenoxy Examples thereof include thermoplastic resins such as resins, epoxy resins, and silicone resins, various thermosetting resins, and copolymers thereof. Among these resins, polycarbonate resin, polyester resin, a copolymer of polycarbonate resin and silicone resin, and a copolymer of polyester resin and silicone resin are preferable. In addition, the mixing ratio in the case of mixing a resin having another structure is not particularly limited, but usually it is preferably used in a range not exceeding the ratio of the polyester resin, specifically, 100 parts by mass of the polyester resin. The content of the resin having another structure relative to is usually 50 parts by mass or less, and preferably 20 parts by mass or less from the viewpoint of wear resistance. Moreover, it is 1 mass part or more normally.

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

≪2. Production method of polyester resin >>
Next, a method for producing a polyester resin used for the electrophotographic photoreceptor to which the exemplary embodiment is applied will be described. As a method for producing the polyester resin, for example, a known polymerization method such as an interfacial polymerization method, a melt polymerization method, or a solution polymerization method can be used. Here, an example of the manufacturing method of a polyester resin is demonstrated.

  In the case of production by the interfacial polymerization method, for example, a solution in which a dihydric phenol compound is dissolved in an alkaline aqueous solution and a halogenated hydrocarbon and aromatic hydrocarbon solution in which an aromatic dicarboxylic acid chloride compound is dissolved are mixed. In this case, a quaternary ammonium salt or a quaternary phosphonium salt can be present as a catalyst. The polymerization temperature is preferably in the range of 0 ° C. to 40 ° C., and the polymerization time is preferably in the range of 2 hours to 20 hours from the viewpoint of productivity. After the completion of the polymerization, the water phase and the organic phase are separated, and the polymer dissolved in the organic phase is washed and recovered by a known method to obtain the intended resin.

Examples of the alkali component used in the interfacial polymerization method include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. As the usage-amount of an alkali component, the range of 1.01 times equivalent-3 times equivalent of the phenolic hydroxyl group contained in a reaction system is preferable.
Examples of the halogenated hydrocarbon include dichloromethane, chloroform, 1,2-dichloroethane, trichloroethane, tetrachloroethane, dichlorobenzene, and the like. Examples of aromatic hydrocarbons include benzene, toluene, xylene and the like.

  Examples of the quaternary ammonium salt or quaternary phosphonium salt used as the catalyst include, for example, salts of tertiary alkylamines such as tributylamine and trioctylamine such as hydrochloric acid, bromic acid and iodic acid; benzyltriethylammonium chloride, benzyltrimethylammonium Examples include chloride, benzyltributylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, trioctylmethylammonium chloride, tetrabutylphosphonium bromide, triethyloctadecylphosphonium bromide, N-laurylpyridinium chloride, laurylpicolinium chloride It is done.

  In the interfacial polymerization method, a molecular weight regulator can be used. Examples of the molecular weight regulator include phenol, o, m, p-cresol, o, m, p-ethylphenol, o, m, p-propylphenol, o, m, p- (tert-butyl) phenol, and pentyl. Alkylphenols such as phenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives; monofunctional phenols such as o, m, p-phenylphenol; acetic acid chloride, butyric acid chloride, octyl Examples thereof include monofunctional acid halides such as acid chloride, benzoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride and substituted products thereof. Among these molecular weight regulators, o, m, p- (tert-butyl) phenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives are preferred because of their high molecular weight controllability and solution stability. It is. Particularly preferred are p- (tert-butyl) phenol, 2,3,6-trimethylphenol, and 2,3,5-trimethylphenol.

  In order not to oxidize the dihydric phenol in the alkaline solution, an antioxidant can be added. Examples of the antioxidant include sodium sulfite, hydrosulfite (sodium hyposulfite), sulfur dioxide, potassium sulfite, sodium hydrogen sulfite and the like. Among these, hydrosulfite is particularly preferable from the viewpoint of the antioxidant effect and reduction of environmental load. As the usage-amount of antioxidant, 0.01 mass% or more and 10.0 mass% or less are preferable with respect to all the bivalent phenols. More preferably, it is 0.1 mass% or more and 5 mass% or less. If the content is too small, the antioxidant effect may be insufficient. If the content is too large, it may remain in the polyester and adversely affect electrical characteristics.

As the purification method after polymerization of the polyester resin, any method can be used as long as the effects of the present invention are not significantly impaired. For example, the polyester resin solution is an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide; hydrochloric acid, An aqueous solution of acid such as nitric acid and phosphoric acid; a method of separating by standing separation, centrifugation, etc. after washing with water or the like.
Other purification methods include, for example, a method in which the produced polyester resin solution is precipitated in a solvent in which the polyester resin is insoluble, a method in which the polyester resin solution is dispersed in warm water, and the solvent is distilled off, or the polyester resin You may refine | purify by the method etc. which distribute | circulate a solution to an adsorption column etc.

The purified polyester resin is precipitated in water, alcohol or other organic solvent in which the polyester resin is insoluble, or the solvent of the polyester resin is distilled off in warm water and in a dispersion medium in which the polyester resin is insoluble, or heated and reduced in pressure. For example, the solvent may be removed by distilling off the solvent, and when the slurry is taken out, the solid can be taken out by a centrifuge or a filter. The obtained polyester resin is usually dried at a temperature equal to or lower than the decomposition temperature of the polyester resin, but can be preferably dried at a temperature not lower than 20 ° C. and not higher than the melting temperature of the resin. At this time, it is preferable to dry under reduced pressure.
Preferably, the drying time is longer than the time until the purity of impurities such as the residual solvent becomes below a certain level. Specifically, the residual solvent is usually 1000 ppm or lower, preferably 300 ppm or lower, more preferably 100 ppm or lower. dry.

≪3. Electrophotographic photoreceptor >>
The electrophotographic photosensitive member to which this embodiment is applied has a photosensitive layer provided on a conductive support, and the photosensitive layer contains the polyester resin. As a specific configuration of the photosensitive layer, for example, a laminate in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material and a binder resin are stacked on a conductive support. And a dispersion type (single layer type) photoreceptor having a photosensitive layer in which a charge generating material is dispersed in a layer containing a charge transport material and a binder resin on a conductive photoreceptor and a conductive support. The polyester resin is usually used for a layer containing a charge transport material, and preferably used for a charge transport layer of a multilayer photoreceptor.

  As a specific configuration of the photosensitive layer used in the electrophotographic photosensitive member to which the exemplary embodiment is applied, for example, in the case of a laminated type photosensitive member, it contains a charge transport material and a binder resin, and retains an electrostatic charge. And a charge transport layer that transports charges generated by exposure, and a charge generation layer that contains a charge generation material and generates charge pairs by exposure. In addition, if necessary, for example, a charge blocking layer for blocking charge injection from the conductive support, a light diffusion layer for diffusing light such as laser light to prevent interference fringes, etc. There is. In the case of a dispersion type (single layer type) photoreceptor, a charge transfer material and a charge generation material are dispersed in a binder resin in the photosensitive layer.

<3-1. Conductive support>
There is no particular limitation on the conductive support, but for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper and nickel, and conductive 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. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Furthermore, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

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

<3-2. Undercoat layer>
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 and a resin in which particles such as a metal oxide are dispersed are used. The undercoat layer may be a single layer or a plurality of layers. The undercoat layer may contain a known antioxidant, pigment particles, resin particles and the like. The film thickness is usually 0.01 μm or more, preferably 0.1 μm or more, from the viewpoint of improving the electrical characteristics, strong exposure characteristics, image characteristics, repeat characteristics, and coating properties during production of the electrophotographic photoreceptor. Usually, it is 30 μm or less, preferably 20 μm or less.

  Examples of 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, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide 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 silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of the several crystal state may be contained.

In addition, various particle sizes of metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is preferably 10 nm or more and 100 nm or less, and particularly 10 nm or more and 50 nm or less. preferable. 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 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 resin. Cellulose esters such as vinylidene resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacryl resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, nitrocellulose 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 titanium alkoxide compounds include known binder resins such as a silane coupling agent. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.
The use ratio of the inorganic particles to the binder resin used in the undercoat layer can be arbitrarily selected. From the viewpoint of the stability of the dispersion and the coating property, the binder resin is usually 10% by mass or more, It is preferable to use in the range of 500 mass% or less.

<3-3. Photosensitive layer>
As a type of the photosensitive layer, a charge generation material and a charge transport material are present in the same layer and are dispersed in a binder resin, a charge generation layer in which a charge generation material is dispersed in a binder resin, and a charge. A functional separation type (laminated type) composed of two layers of a charge transport layer in which a transport material is dispersed in a binder resin can be mentioned, but any type may be used.
In addition, as the laminated photosensitive layer, a charge generation layer and a charge transport layer are laminated in this order from the conductive support side, and a charge transport layer and a charge generation layer are laminated in this order. There are reverse laminated type photosensitive layers, and any of them can be adopted, but a forward laminated type photosensitive layer capable of exhibiting the most balanced photoconductivity is preferable.

<3-3-1. Multilayer photosensitive layer>
[Charge generation layer]
In the case of a laminated type photoreceptor (function separation type photoreceptor), the charge generation layer is formed by binding a charge generation material with a binder resin. The film thickness is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less.

  Examples of the charge generation material include inorganic photoconductive materials such as selenium and its alloys, cadmium sulfide, and organic photoconductive materials such as organic pigments, but organic photoconductive materials are preferred, especially organic pigments. Is preferred. Examples of organic pigments include phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. . Among these, phthalocyanine pigments or azo pigments are particularly preferable. When organic pigments are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

  When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a photosensitive member having a high sensitivity to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm, is obtained. When an azo pigment such as diazo or trisazo is used, it is sufficient for white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength, for example, laser having a wavelength around 450 nm or 400 nm. A photosensitive member having a high sensitivity can be obtained.

When an organic pigment is used as the charge generating material, a phthalocyanine pigment or an azo pigment is particularly preferable. The phthalocyanine pigment provides a photosensitive material with high sensitivity to a laser beam having a relatively long wavelength, and the azo pigment has a sufficient sensitivity to white light and a laser beam having a relatively short wavelength. , Each is excellent.
When using a phthalocyanine pigment as a charge generation material, specifically, metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum or other metal or oxide thereof, halide, water Those having crystal forms of coordinated phthalocyanines such as oxides and alkoxides, and phthalocyanine dimers using oxygen atoms as bridging atoms are used. Particularly, titanyl phthalocyanines (also known as oxytitanium) such as X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), and D-type (also known as Y-type), which are highly sensitive crystalline Phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, hydroxyindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, type II, etc. The [mu] -oxo-aluminum phthalocyanine dimer is preferred.

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

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

When an azo pigment is used as the charge generation material, various bisazo pigments and trisazo pigments are preferably used.
When an 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.

The binder resin used for the charge generation layer is not particularly limited, but examples include polyvinyl butyral resin, polyvinyl formal resin, polyvinyl acetal type such as partially acetalized polyvinyl butyral resin in which part of butyral is modified with formal, acetal, or the like. Resin, Polyarylate resin, Polycarbonate resin, Polyester resin, Modified ether type polyester resin, Phenoxy resin, Polyvinyl chloride resin, Polyvinylidene chloride resin, Polyvinyl acetate resin, Polystyrene resin, Acrylic resin, Methacrylic resin, Polyacrylamide resin, Polyamide Resin, polyvinyl pyridine resin, cellulosic resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, vinyl chloride -Vinyl acetate-vinyl acetate copolymers such as vinyl acetate copolymers, hydroxy-modified vinyl chloride-vinyl acetate copolymers, carboxyl-modified vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, etc. Insulating resins such as polymers, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, styrene-alkyd resins, silicon-alkyd resins, phenol-formaldehyde resins, poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl And organic photoconductive polymers such as perylene. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.
In the charge generation layer, the mixing ratio (mass) of the binder resin and the charge generation material is usually 10 parts by mass or more, preferably 30 parts by mass or more, and usually 1000 parts by mass with respect to 100 parts by mass of the binder resin. Part or less, preferably 500 parts by weight or less.

[Charge transport layer]
The charge transport layer of the multilayer photoreceptor contains a charge transport material and usually contains a binder resin and other components used as necessary. The charge transport layer may be composed of a single layer, or may be a stack of a plurality of layers having different constituent components or composition ratios. The film thickness is usually 5 μm to 50 μm, preferably 10 μm to 45 μm.

  The charge transport material is not particularly limited, and any material can be used. Examples of charge transport materials include aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, electron withdrawing materials such as quinone compounds such as diphenoquinone, carbazole derivatives, indoles Derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives and multiple types of these compounds bind Or an electron donating substance such as a polymer having a group consisting of these compounds in the main chain or side chain. Among these, carbazole derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine derivatives, and those in which a plurality of these compounds are bonded are preferable. These charge transport materials may be used alone or in combination. Specific examples of suitable structures of the charge transport material are shown below.

The polyester resin is preferably used as a binder resin for a charge transport layer. The binder resin may be a mixture of the polyester resin and a resin having another structure. Examples of the other resin include those described in Resins having other structures mixed in the photosensitive layer.
The proportion of the polyester resin and the charge transport material is usually preferably 30 parts by mass or more for the charge transport material with respect to 100 parts by mass of the binder resin, and 40 parts by mass or more from the viewpoint of electrical characteristics. Moreover, usually 200 mass parts or less and 150 mass parts or less are preferable from a viewpoint of abrasion resistance. The ratio of the binder resin as a whole to the charge transport material in the photosensitive layer is such that the charge transport material is used in a ratio of 20 parts by mass or more with respect to 100 parts by mass of the binder resin. Among these, 30 parts by mass or more is preferable from the viewpoint of residual potential reduction, and 40 parts by mass or more is more preferable from the viewpoint of stability and charge mobility when repeatedly used. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, the charge transport material is usually used at a ratio of 150 parts by mass or less. Especially, 100 mass parts or less are preferable from a compatible viewpoint of charge transport material and binder resin.

  It should be noted that the charge transport layer has well-known plasticizers, antioxidants, ultraviolet absorbers, and electron withdrawing properties in order to improve film forming properties, flexibility, coating properties, stain resistance, gas resistance, light resistance, etc. You may contain additives, such as a compound, dye, a pigment, and a leveling agent. Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of dyes and pigments include various pigment compounds and azo compounds.

<3-3-2. Single-layer type photosensitive layer>
The single-layer type photosensitive layer is formed using a binder resin in order to ensure film strength, in the same manner as the charge transport layer of the multilayer photoconductor, 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 a conductive support (or an 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. The charge generating material is further dispersed in the charge transport medium comprising these charge transport material and 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. Usually 0.5% by mass or more, preferably 1% by mass or more, and usually 50% by mass with respect to the entire layer-type photosensitive layer.
Hereinafter, it is preferably used in the range of 20% by mass or less.
In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. 30 parts by mass or less, preferably 10 parts by mass 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. Also in this case, a known plasticizer for improving film formability, flexibility, mechanical strength, an additive for suppressing residual potential, a dispersion aid for improving dispersion stability, and coating properties are provided. Leveling agents and surfactants for improvement, such as silicone oil, fluorine oil and other additives may be added.

<3-4. Other functional layers>
For the purpose of improving film forming properties, flexibility, coating properties, contamination resistance, gas resistance, light resistance, etc., in both the photosensitive layer and the layers constituting the photosensitive layer, both of the multilayer type photosensitive member and the single layer type photosensitive member. Additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents may be contained. 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 fluorine resin, silicon resin, polyethylene resin, etc. Particles made of the above resin or inorganic compound particles may be contained in the surface layer. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer. Further, if necessary, it may have a layer for improving electrical properties and mechanical properties, such as an intermediate layer such as a barrier layer, an adhesive layer and a blocking layer, and a transparent insulating layer.

<3-5. Formation method of each layer>
Each layer constituting these photoreceptors is formed by immersing, coating, spraying, nozzle coating, bar coating, roll coating, blade coating, etc., on a support, a coating solution obtained by dissolving or dispersing a substance to be contained in a solvent. In this method, the coating and drying steps are sequentially repeated for each layer.

  There are no particular restrictions on the solvent or dispersion medium used in the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene and xylene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1, Chlorinated hydrocarbons such as 2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine , Nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Among these solvents, non-halogen solvents are preferable from the viewpoint of environmental considerations, and toluene, xylene, anisole, dimethoxyethane, tetrahydrofuran, and 1,4-dioxane are particularly preferable from the viewpoint of solubility. Any one of these may be used alone, or two or more of these may be used in combination.

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

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

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

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. Examples of the charging device include a corona charging device such as a corotron and a scorotron, a direct charging device (contact type charging device) that charges a direct charging member to which a voltage is applied by contacting the photosensitive member surface, and a contact type charging device such as a charging brush. Often used. Examples of direct charging means include contact chargers such as charging rollers and charging brushes. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2. As the direct charging means, either charging with air discharge or injection charging without air discharge is possible. Moreover, as a voltage applied at the time of charging, it is possible to use only a direct current voltage or to superimpose an alternating current on a direct current.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a short wavelength of 380 nm to 500 nm. . Among these, it is preferable to use light having a short wavelength of 380 to 500 nm because the resolution becomes high. Among these, 405 nm monochromatic light is preferable.

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

  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.

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.
In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.

Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.
The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.

When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.
After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.

  In addition to the above-described configuration, the image forming apparatus may be configured to perform, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform 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 electrophotographic 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 ( The electrophotographic photosensitive member cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, for example, when the electrophotographic photosensitive member 1 and other members are deteriorated, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic photosensitive member cartridge is mounted on the main body of the image forming apparatus. This facilitates maintenance and management of the image forming apparatus.

Specific embodiments of the present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.
[Production of polyester resin]
Production Example 1 (Method for producing polyester resin (1))
Sodium hydroxide (8.32 g) and H ₂ O (383 ml) were weighed in a 500 mL beaker and dissolved with stirring. 2,3,5-trimethylphenol (0.57 g), 1,1-bis (4-hydroxy-3-methylphenyl) ethane (20.47 g) (hereinafter referred to as BP1), benzyltriethylammonium chloride (0 .23 g) was added in this order and dissolved by stirring, and the aqueous alkaline solution was transferred to a 2 L reaction vessel. Separately, mixing of diphenyl ether-4,4′-dicarbonyl chloride (17.94 g) (hereinafter DC1), 4,4′-diphenyldicarbonyl chloride (7.27 g) (hereinafter DC2) and dichloromethane (215 mL) The solution was transferred into a dropping funnel.

  While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (286 mL) was added and stirring was continued for 9 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed 3 times with 0.1N hydrochloric acid (380 mL), and further washed twice with demineralized water (380 mL).

  The washed organic layer was diluted with 500 ml of methylene chloride, poured into methanol (4000 ml), and the resulting precipitate was filtered off and dried to obtain the desired polyester resin (1). The viscosity average molecular weight of the obtained polyester resin (1) was 46,600. The structural formula of the obtained polyester resin (1) is shown below.

[Measurement of viscosity average molecular weight]
The polyester resin was dissolved in dichloromethane to prepare a solution having a concentration C of 6.00 g / L. The flow time t of the sample solution was measured in a constant temperature water bath set at 20.0 ° C. using an Ubbelohde capillary viscometer with a flow time t ₀ of the solvent (dichloromethane) of 136.16 seconds. The viscosity average molecular weight (Mv) was calculated according to the following formula.
a = 0.438 × η _sp +1 η _sp = t / t ₀ −1
b = 100 × η _sp / C C = 6.00 (g / L)
η = b / a
Mv = 3207 × η ^1.205

Production Example 2 (Production Method of Polyester Resin (2))
Sodium hydroxide (4.19 g) and H ₂ O (188 ml) were weighed in a 500 mL beaker and dissolved with stirring. Then, 2,3,5-trimethylphenol (0.26 g), BP1 (10.33 g) and benzyltriethylammonium chloride (0.11 g) were added in this order and dissolved by stirring, and then this alkaline aqueous solution was added to a 1 L reaction vessel. Moved. Separately, a mixed solution of DC1 (6.48 g), DC2 (6.16 g) and dichloromethane (107 mL) was transferred into the dropping funnel.

  While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (143 mL) was added and stirring was continued for 9 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed 3 times with 0.1N hydrochloric acid (188 mL), and further washed twice with demineralized water (188 mL).

  The washed organic layer was diluted with 200 ml of methylene chloride, poured into methanol (1800 ml), and the resulting precipitate was filtered off and dried to obtain the desired polyester resin (2). The viscosity average molecular weight of the obtained polyester resin (2) was 46,000. The structural formula of the obtained polyester resin (2) is shown below.

Production Example 3 (Method for producing polyester resin (3))
Sodium hydroxide (4.04 g) and H ₂ O (190 ml) were weighed in a 500 mL beaker and dissolved with stirring. 2,3,5-trimethylphenol (0.28 g), 2,2-bis (4-hydroxy-3-methylphenyl) propane (10.52 g) (hereinafter referred to as BP2), benzyltriethylammonium chloride (0 .11 g) in this order, and dissolved by stirring, and then the aqueous alkaline solution was transferred to a 1 L reaction vessel.

Separately, a mixed solution of DC1 (8.71 g), DC2 (3.53 g) and dichloromethane (107 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (143 mL) was added and stirring was continued for 9 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed 3 times with 0.1N hydrochloric acid (188 mL), and further washed twice with demineralized water (188 mL).

The washed organic layer was diluted with 200 ml of methylene chloride, poured into methanol (1800 ml), and the resulting precipitate was filtered off and dried to obtain the desired polyester resin (3). The viscosity average molecular weight of the obtained polyester resin (3) was 40,600. The structural formula of the obtained polyester resin (3) is shown below.

Production Example 4 (Production Method of Polyester Resin (4))
Sodium hydroxide (4.22 g) and H ₂ O (202 ml) were weighed in a 500 mL beaker and dissolved with stirring. Then, 2,3,5-trimethylphenol (0.29 g), BP1 (10.38 g) and benzyltriethylammonium chloride (0.11 g) were added in this order and dissolved by stirring, and then this alkaline aqueous solution was added to a 1 L reaction vessel. Moved. Separately, a mixed solution of DC1 (3.90 g), DC2 (8.60 g) and dichloromethane (188 mL) was transferred into the dropping funnel.

  While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (85 mL) was added and stirring was continued for 9 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed 3 times with 0.1N hydrochloric acid (205 mL), and further washed twice with demineralized water (205 mL).

  The washed organic layer was diluted with 210 ml of methylene chloride, poured into methanol (2000 ml), and the resulting precipitate was filtered out and dried to obtain the desired polyester resin (4). The viscosity average molecular weight of the obtained polyester resin (4) was 52,000. The structural formula of the obtained polyester resin (4) is shown below.

Production Example 5 (Method for producing polyester resin (5))
In Production Example 4, DC1 (3.90 g) and DC2 (8.60 g) were changed to DC2 (12.42 g). Otherwise in the same manner as in Production Example 4, a polyester resin (5) was obtained. The viscosity average molecular weight of the obtained polyester resin (5) was 55,600. The structural formula of the obtained polyester resin (5) is shown below.

Production Example 6 (Method for producing polyester resin (6))
A polyester resin (6) (viscosity average molecular weight 36,200) having the following structure was produced by the method described in Example 6 of JP-A-2006-53549.

Production Example 7 (Method for producing polyester resin (7))
Sodium hydroxide (5.71 g) and H ₂ O (235 ml) were weighed in a 500 mL beaker and dissolved with stirring. Then, 2,3,5-trimethylphenol (0.36 g), BP1 (14.08 g), benzyltriethylammonium chloride (0.15 g) were added in this order and dissolved by stirring, and then this alkaline aqueous solution was added to a 1 L reaction vessel. Moved. Separately, a mixed solution of DC1 (8.80 g), terephthalic acid chloride (3.03 g) (hereinafter DC3), isophthalic acid chloride (3.03 g) (hereinafter DC4) and dichloromethane (118 mL) is placed in the dropping funnel. Moved.

  While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (195 mL) was added and stirring was continued for 9 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed with 0.1N hydrochloric acid (235 mL) three times, and further washed twice with demineralized water (235 mL).

  The washed organic layer was diluted with 300 ml of methylene chloride, poured into methanol (2400 ml), and the resulting precipitate was removed by filtration and dried to obtain the desired polyester resin (7). The viscosity average molecular weight of the obtained polyester resin (7) was 41,100. The structural formula of the obtained polyester resin (7) is shown below.

Production Example 8 (Production Method of Polyester Resin (8))
In Production Example 7, DC1 was changed to the same equivalent of DC2. Otherwise in the same manner as in Production Example 7, a polyester resin (8) was obtained. The viscosity average molecular weight of the obtained polyester resin (8) was 52,100. The structural formula of the obtained polyester resin (8) is shown below.

<Preparation of photoreceptor sheet>
[Example 1]
10 parts by mass of oxytitanium phthalocyanine and 150 parts by mass of 4-methoxy-4-methyl-2-pentanone were mixed and pulverized and dispersed in a sand grind mill to produce a pigment dispersion. Oxytitanium phthalocyanine has Bragg angles (2θ ± 0.2) of 9.3 °, 10.6 °, 13.2 °, 15.1 °, 15.7 °, 16.5 ° in X-ray diffraction by CuKα ray. Strong diffraction peaks are shown at 1 °, 20.8 °, 23.3 °, 26.3 °, and 27.1 °.

  To this pigment dispersion, 50 parts by mass of a 5 mass% 1,2-dimethoxyethane solution of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name Denkabutyral # 6000C), phenoxy resin (manufactured by Union Carbide Co., Ltd., trade name) 50 parts by mass of a 5% by mass 1,2-dimethoxyethane solution of PKHH) and then adding an appropriate amount of 1,2-dimethoxyethane to prepare a coating solution for forming a charge generation layer having a solid content concentration of 4.0% did. This charge generation layer forming coating solution was applied on a polyethylene terephthalate sheet having aluminum deposited on the surface so that the film thickness after drying was 0.4 μm and dried to provide a charge generation layer.

  Next, as a charge transport material, a mixture (CTM-1) produced by the method described in Example 1 of JP-A-2002-080432, which comprises a group of geometric isomers having a structure shown below as a main component. ), 100 parts by mass of the polyester resin (1) produced in Production Example 1, 8 parts by mass of an antioxidant (Irganox 1076), 0.05 parts by mass of silicone oil as a leveling agent, tetrahydrofuran and toluene Was mixed with 640 parts by mass of a mixed solvent (80% by mass of tetrahydrofuran, 20% by mass of toluene) to prepare a coating solution for forming a charge transport layer.

This charge transport layer forming coating solution is applied onto the above-described charge generation layer using an applicator so that the film thickness after drying is 25 μm, and dried at 125 ° C. for 20 minutes to form a charge transport layer. A photoreceptor sheet was prepared.
[Example 2]
A photoreceptor sheet was produced in the same manner as in Example 1 except that the polyester resin (1) was changed to the polyester resin (2).

[Example 3]
A photoreceptor sheet was produced in the same manner as in Example 1 except that the polyester resin (1) was changed to the polyester resin (3).
[Example 4]
A photoreceptor sheet was produced in the same manner as in Example 1 except that the polyester resin (1) was changed to the polyester resin (4).

[Comparative Example 1]
A photoreceptor sheet was produced in the same manner as in Example 1 except that the polyester resin (1) was changed to the polyester resin (5).
[Comparative Example 2]
A photoreceptor sheet was produced in the same manner as in Example 1 except that the polyester resin (1) was changed to the polyester resin (6).

[Comparative Example 3]
A photoreceptor sheet was produced in the same manner as in Example 1 except that the polyester resin (1) was changed to the polyester resin (7).
[Comparative Example 4]
A photoreceptor sheet was produced in the same manner as in Example 1 except that the polyester resin (1) was changed to the polyester resin (8).

[Electrical characteristics evaluation]
Using an electrophotographic characteristic evaluation apparatus (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404-405) prepared according to the Electrophotographic Society measurement standard, the photoconductor is made into an aluminum drum. Attached to a cylindrical shape, the aluminum drum and the aluminum base of the photoconductor are connected, and then the drum is rotated at a constant rotational speed, and an electrical property evaluation test is performed by a cycle of charging, exposure, potential measurement, and static elimination. went. At that time, the initial surface potential was set to −700 V, the exposure was performed at 780 nm and the charge removal was performed at 660 nm, and the surface potential (VL) at the time when the exposure light was irradiated by 4.6 μJ / cm 2 was measured. In the VL measurement, the time required from the exposure to the potential measurement was 139 ms. The irradiation energy (half exposure energy: μJ / cm ² ) when the surface potential was half of the initial surface potential (−350 V) was measured as sensitivity (E _1/2 ). The smaller the absolute value of the VL value, the better the electrical characteristics, and the smaller the E _1/2 value, the higher the sensitivity. The measurement environment was 25 ° C. and 50% relative humidity (N / N). The results are shown in Table-1.

[Abrasion test]
The photoreceptor film was cut into a circle having a diameter of 10 cm, and the wear was evaluated by a Taber abrasion tester (manufactured by Toyo Seiki Co., Ltd.). The test conditions were measured by comparing the mass before and after the test after 1000 rotations under a load of 1500 g using a wear wheel CS-10F in an atmosphere of 25 ° C. and 50% RH. The results are shown in Table-1.

<Production of photosensitive drum>
[Example 5]
The undercoat layer dispersion was prepared as follows. High-speed fluidized mixing of rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) Disperse the surface-treated titanium oxide obtained by mixing in a kneading machine (“SMG300” manufactured by Kawata Co., Ltd.) and mixing at high speed at a rotational peripheral speed of 34.5 m / sec using a ball mill of methanol / 1-propanol. Thus, a dispersion slurry of hydrophobized titanium oxide was obtained. 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 ( Compound represented by B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula The compound represented by (E)] has a composition molar ratio of 75% / 9.5% / 3% / 9.5% / 3%, and is stirred and mixed while heating with the copolyamide pellets. After dissolving the polyamide pellets, by carrying out ultrasonic dispersion treatment, the mass ratio of methanol / 1-propanol / toluene is 7/1/2, and hydrophobically treated titanium oxide / copolymerized poly Containing bromide at a weight ratio 3/1 was undercoat layer dispersion having a solid concentration of 18.0%.

  The charge generation layer forming coating solution was prepared as follows. As a charge generation material, 20 parts of Y-type (also known as D-type) oxytitanium phthalocyanine and 1,2- 1, which show a strong diffraction peak at 27.3 ° in the Bragg angle (2θ ± 0.2) in X-ray diffraction by CuKα rays. 280 parts of dimethoxyethane were mixed and pulverized with a sand grind mill for 1 hour for atomization dispersion treatment. Subsequently, 10 parts of polyvinyl butyral (trade name “Denka Butyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-methyl. A binder solution obtained by dissolving in a mixed solution of 85 parts of -2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution β for forming a charge generation layer.

  The charge transport layer coating solution was prepared as follows. 75 parts by mass of a charge transport material comprising an isomer mixture mainly composed of the charge transport material (CTM-1), 100 parts by mass of the polyester resin (1) produced in Production Example 1, and an antioxidant (Irganox 1076) ) 4 parts by mass, 0.05 part by mass of silicone oil (trade name KF96, manufactured by Shin-Etsu Chemical Co., Ltd.) is mixed with 640 parts by mass of a tetrahydrofuran / toluene mixed solvent (tetrahydrofuran 80% by mass, toluene 20% by mass) to form a charge transport layer. A coating solution was prepared.

  Subsequently, a cylinder made of an aluminum alloy having an outer diameter of 30 mm, a length of 248 mm, and a wall thickness of 0.75 mm, whose surface is roughly cut, is anodized, and then sealed with a sealing agent mainly composed of nickel acetate. By performing the treatment, an anodic oxide coating (alumite coating) of about 6 μm was formed. The undercoating layer forming coating solution, the charge generating layer forming coating solution, and the charge transport layer forming coating solution obtained as described above were sequentially applied to the obtained cylinder by a dip coating method, dried, and dried. An undercoat layer, a charge generation layer, and a charge transport layer were formed so that the film thicknesses were 1.5 μm, 0.4 μm, and 32 μm, respectively, and a photosensitive drum was manufactured. The charge transport layer was dried at 125 ° C. for 24 minutes to produce a photoreceptor drum D1.

<Image test>
The obtained photoreceptor is mounted on a photoreceptor cartridge of a monochrome printer SCX-6555N manufactured by Samsung, and 300,000 sheets are continuously printed at a printing rate of 5% at a temperature of 25 ° C. and a relative humidity of 50%. It was. The thickness of the charge transport layer after printing was measured, and the film thickness was confirmed by comparing the thickness of the charge transport layer before and after printing, and the printing durability was evaluated. The results are shown in Table-2.

<Evaluation of electrophotographic photoreceptor>
The obtained electrophotographic photosensitive member is attached to an electrophotographic characteristic evaluation apparatus ("Basic and Application of Secondary Electrophotographic Technology" edited by Electrophotographic Society, Corona, pages 404 to 405) prepared according to the Electrophotographic Society standard. The electrical characteristics were evaluated by carrying out a cycle of charging, exposure, potential measurement, and static elimination according to the following procedure.

  After charging so that the initial surface potential of the photosensitive member becomes −800 V under the conditions of a temperature of 25 ° C. and a humidity of 50%, the light from the halogen lamp is converted to a monochromatic light of 780 nm with an interference filter and irradiated with 1.0 μJ / cm 2. The surface potential (VL) measured after energy exposure and 97 msec after exposure was defined as the residual potential. The results are shown in Table-2.

[Comparative Example 5]
A photoconductive drum D2 was produced in the same manner as in Example 5 except that the polyester resin (1) was changed to the polyester resin (5).

  From the results shown in Table-1 and Table-2, the polyester resin within the scope of the present invention exhibits sufficient solubility even in a non-halogen solvent, and the provided photoreceptor has electrical characteristics, abrasion resistance and adhesion. It was revealed that the property was good.

1 Photoconductor 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 (7)

It has a conductive support and a photosensitive layer formed on the conductive support, and the photosensitive layer is a divalent carboxylic acid residue represented by the following formula (1), represented by the following formula (2). A polyester resin having a repeating structure of a divalent carboxylic acid residue and a divalent phenol residue represented by the following formula (3), the following formula (1) and the following formula (2) of the polyester resin: The amount of the divalent carboxylic acid residue represented by formula (1) is 70 mol% or more based on the total carboxylic acid residues, and the content of the divalent carboxylic acid residue represented by the formula (1) is: An electrophotographic photosensitive member satisfying 0.3 ≦ (1) / ((1) + (2)) ≦ 0.9 in terms of molar ratio.

(In the formula ^(1), each R 1, ^{R 2} are independently an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or a benzyl group, n, m is , Represents an integer of 0 to 4.)

(In the formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or a benzyl group, p Q represents an integer of 0 to 4.)

(In formula (3), R ^{5 to} R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a halogenated alkyl group, a benzyl group, or an aryl group. X ¹ represents a single bond, an alkylene group, —CR ⁹ R ¹⁰ —, an oxygen atom, or a sulfur atom.
⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, or a group that forms a ring in which R ⁹ and R ¹⁰ are bonded to each other and may have a substituent. Show. )   In the polyester resin, the content of the divalent carboxylic acid residue represented by the formula (1) satisfies 0.5 ≦ (1) / ((1) + (2)) ≦ 0.8 in molar ratio. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is satisfied. In the polyester resin, the divalent carboxylic acid residue represented by the formula (1) is a dicarboxylic acid represented by the following formula (4) and a divalent carboxylic acid residue represented by the formula (2). The electrophotographic photosensitive member according to claim 1, wherein is a dicarboxylic acid represented by the following formula (5).

4. The polyester resin according to claim 1, wherein the divalent phenol residue represented by the formula (3) is a divalent phenol residue represented by the following formula (6). 5. Electrophotographic photoreceptor.

(In Formula (6), X ² represents a single bond, an alkylene group, or —CR ¹¹ R ¹² —. R ¹¹ and R ¹² each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. .)   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is formed using a coating solution containing a non-halogen solvent.   The electrophotographic photosensitive member according to claim 1, a charging device that charges the electrophotographic photosensitive member, and an exposure device that forms an electrostatic latent image by exposing the charged electrophotographic photosensitive member. And a developing device for developing the electrostatic latent image formed on the electrophotographic photosensitive member. In a polyester resin having a repeating structure of a divalent carboxylic acid residue and a divalent phenol residue, a divalent carboxylic acid residue represented by the following formula (1) and a divalent carboxylic acid represented by the following formula (2) It has a repeating structure of a residue and a divalent phenol residue represented by the following formula (3), and the amount of divalent carboxylic acid residues represented by the following formula (1) and the following formula (2) is all The content of the divalent carboxylic acid residue represented by the formula (1) is 70 mol% or more based on the carboxylic acid residue, and the molar ratio is 0.3 ≦ (1) / ((1) + (2)) ≦ 0.9, a polyester resin.

(In the formula ^(1), each R 1, ^{R 2} are independently an alkyl group having 1 to 10 carbon atoms, 1 to carbon atoms
10 alkoxyl group, a halogenated alkyl group, or a benzyl group is shown, n and m show the integer of 0-4. )

(In the formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a halogenated alkyl group, or a benzyl group, p Q represents an integer of 0 to 4.)

(In formula (3), R ^{5 to} R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a halogenated alkyl group, a benzyl group, or an aryl group. X ¹ represents a single bond, an alkylene group, —CR ⁹ R ¹⁰ —, an oxygen atom, or a sulfur atom.
⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, or a group that forms a ring in which R ⁹ and R ¹⁰ are bonded to each other and may have a substituent. Show. )

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