JP5040318B2 - Photosensitive layer forming coating solution, electrophotographic photosensitive member, electrophotographic photosensitive member cartridge, and image forming apparatus - Google Patents

Description

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

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

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

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

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

  In the case of a general photoreceptor having no functional layer such as a surface protective layer, it is the photosensitive layer that receives such a load. The photosensitive layer is usually composed of a binder resin and a photoconductive substance, and the binder resin substantially determines the strength. However, since the doping amount of the photoconductive substance is considerably large, the conventional technology has not yet provided the photosensitive layer with sufficient mechanical strength.

  In addition, due to the increasing demand for high-speed printing, materials that can cope with higher-speed electrophotographic processes have been demanded. When performing high-speed printing, the time from exposure to development is shortened. Therefore, it is desired that the photosensitive member has good responsiveness in addition to high sensitivity and long life. The responsiveness of the photoreceptor is governed by the charge transport layer, particularly the charge transport material, but is known to vary greatly depending on the binder resin.

  Each layer constituting these electrophotographic photoreceptors is usually formed by applying a coating liquid containing a photoconductive substance, a binder resin or the like on a conductive support. At this time, as the coating method, for example, methods such as dip coating, spray coating, nozzle coating, bar coating, roll coating, blade coating, etc. are used. In these layer forming methods, for example, a known method such as preparing a coating solution in which a substance to be contained in a layer is dissolved in a solvent and applying the coating solution is applied.

  In many processes, a coating solution is prepared in advance and stored. For this reason, the binder resin is also desired to have excellent solubility in the solvent used in the coating step and excellent stability of the coating solution after dissolution. In particular, when the photoconductive substance (especially the charge transporting substance) contains an aliphatic multiple bond (mostly a double bond), a coating liquid configuration that does not decompose is desired.

  Examples of the binder resin of the photosensitive layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, thermoplastic resins such as polycarbonate, polyester, polysulfone, phenoxy, epoxy, and silicone resins, and various types. The thermosetting resin is used. Among the various binder resins, the polycarbonate resin has a relatively excellent performance, and various polycarbonate resins have been developed and put into practical use (see, for example, Patent Documents 1 to 4).

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

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

  Conventional photoreceptors may be worn or scratched by practical loads such as development with toner, friction with transfer members and paper, and friction with cleaning members (blades). It was. For this reason, at present, the printing performance using the photosensitive member is limited to practically limited printing performance.

  In addition, the electrophotographic photosensitive member using the conventionally known polyester resin is improved in strength and the like as compared with the case of using other resins, but is poor in stability when used as a coating solution for forming a photosensitive layer, and is cloudy. And problems such as precipitation and insolubilization occurred. In addition, the electrical characteristics of the photosensitive member may be deteriorated due to the structural deterioration of the components in the coating solution over time.

  The present invention was devised to solve the above-described problems, and provides a photosensitive layer that is excellent in stability over time of electrical characteristics and excellent in both electrical characteristics and wear resistance when a photosensitive layer is formed. It is an object of the present invention to provide a coating solution for forming a photosensitive layer, an electrophotographic photoreceptor excellent in both electrical characteristics and wear resistance, an electrophotographic photoreceptor cartridge and an image forming apparatus using the electrophotographic photoreceptor.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have liquid properties and electrical characteristics over time by including a polyester resin having a specific structure and an antioxidant in the photosensitive layer forming coating solution. The electrophotographic photosensitive member produced using the coating solution was found to be stable and found to have sufficient mechanical properties and good electrical properties, resulting in the completion of the present invention. .

（前記式（１）中、Ａｒ¹〜Ａｒ⁴は、それぞれ独立に、置換基を有していてもよいアリーレン基を表わし、Ｘ¹は単結合または二価基を表わす。） Specifically, the subject matter of the present invention is a photosensitive layer forming coating solution for forming the photosensitive layer of the electrophotographic photosensitive member having a photosensitive layer on a conductive support, the coating solution for photosensitive layer formation, the following A polyester resin containing a repeating structure represented by the formula (1), an antioxidant, and a charge transport material, wherein the charge transport material contains at least one of a stilbene derivative and a butadiene derivative. The present invention resides in a coating solution for forming a photosensitive layer.

(In the formula (1), Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X ¹ represents a single bond or a divalent group.)

（式（２）中、Ａｒ⁵〜Ａｒ⁸は、それぞれ独立に、置換基を有していてもよいフェニレン基を表わし、Ｒ¹は水素原子またはメチル基を表わす。） At this time, it is preferable that this polyester resin contains the repeating structure represented by following formula (2) (Claim 2).

(In formula (2), Ar ^{5 to} Ar ⁸ each independently represents a phenylene group which may have a substituent, and R ¹ represents a hydrogen atom or a methyl group.)

  Moreover, it is preferable that this antioxidant is a phenolic antioxidant (Claim 3).

  Another gist of the present invention resides in an electrophotographic photosensitive member comprising a layer formed by coating the photosensitive layer forming coating solution on a conductive support (claim 4).

Still another subject matter of the present invention is an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer includes a polyester resin having a repeating structure represented by the formula (1), and an antioxidant. An electrophotographic photoreceptor comprising an agent and a charge transporting material, wherein the charge transporting material contains at least one of a stilbene derivative and a butadiene derivative .

  At this time, it is preferable that this polyester resin contains the repeating structure represented by said Formula (2) (Claim 6).

  Moreover, it is preferable that this antioxidant is a phenolic antioxidant (Claim 7).

  Further, the electrophotographic photosensitive member is preferably used for monochromatic writing light having a wavelength of 380 to 500 nm.

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

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

  In this case, it is preferable that the exposure means performs exposure with monochromatic light having an exposure wavelength of 380 nm to 500 nm.

The coating solution for forming a photosensitive layer of the present invention is excellent in stability over time of electrical characteristics, and by using this, a photosensitive layer excellent in electrical characteristics and abrasion resistance can be formed.
Furthermore, according to the present invention, an electrophotographic photoreceptor excellent in electrical characteristics and abrasion resistance, and an electrophotographic photoreceptor cartridge and an image forming apparatus using the electrophotographic photoreceptor can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can implement in various deformation | transformation.

[I. Coating liquid]
The coating solution for forming a photosensitive layer of the present invention (hereinafter referred to as “the coating solution of the present invention” as appropriate) is a coating solution for forming a photosensitive layer of an electrophotographic photosensitive member (photosensitive member). The photoreceptor has a photosensitive layer on a conductive support (substrate).
The photosensitive layer of the photoreceptor is provided on the conductive support, and if the photoreceptor has an undercoat layer, it is provided on the undercoat layer (that is, on the conductive support via the undercoat layer). It is done. The type of the photosensitive layer is usually a type (single layer type or dispersed type) photosensitive layer in which the charge generation material and the charge transport material are present in the same layer and dispersed or dissolved in the binder resin; A mold (laminated layer) having a functionally separated structure of a charge generation layer in which a generating material is dispersed or dissolved in a binder resin and a charge transport layer in which a charge transporting material is dispersed or dissolved in a binder resin. Type or function separation type) photosensitive layer. A photoreceptor having a single layer type photosensitive layer is a so-called single layer type photoreceptor (or a dispersion type photoreceptor), and a photoreceptor having a laminated type photosensitive layer is a so-called laminated type photoreceptor (or function separation). The photosensitive layer may be of any configuration.

Further, as the laminated photosensitive layer, a charge generating layer and a charge transport layer are laminated in this order from the conductive support side, and 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. Among these, a forward laminated photosensitive layer that can exhibit the most balanced photoconductivity is preferable.
The coating solution of the present invention is used for forming the photosensitive layer. When the photosensitive layer is composed of two or more layers (for example, a charge generation layer and a charge transport layer), the coating solution of the present invention forms at least one of the layers constituting the photosensitive layer. It is used for.

  Furthermore, the coating liquid of the present invention contains a polyester resin having a specific repeating structure (hereinafter referred to as “polyester resin according to the present invention” as appropriate) and an antioxidant. In addition, the coating liquid of the present invention further contains a solvent, a charge generation material, a charge transport material, an additive and the like as appropriate.

（前記式（１）中、Ａｒ¹〜Ａｒ⁴は、それぞれ独立に、置換基を有していてもよいアリーレン基を表わし、Ｘ¹は単結合または二価基を表わす。） [I-1. Polyester resin]
The polyester resin according to the present invention is a polyester resin including a repeating structure represented by the following formula (1).

(In the formula (1), Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X ¹ represents a single bond or a divalent group.)

In the formula (1), Ar ^{1 to} Ar ⁴ each independently represents an arylene group.
The carbon number of Ar ^{1 to} Ar ⁴ is arbitrary as long as the effects of the present invention are not significantly impaired. However, the carbon number of Ar ¹ and Ar ² is usually 6 or more, usually 20 or less, preferably 12 or less, particularly preferably 7. Ar ³ and Ar ⁴ usually have 6 or more carbon atoms, usually 20 or less, preferably 12 or less, and particularly preferably 6.

The number of rings Ar ^{1 to} Ar ⁴ is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 1 or more, usually 3 or less, preferably 2 or less, and particularly preferably 1.

Specific examples of Ar ^{1 to} Ar ⁴ include a phenylene group, a naphthylene group, a 3-methylphenylene group, and a 3-phenylphenylene group. In addition, examples include an anthrylene group, a phenanthrylene group, a pyrenylene group, and the like. Among these, a phenylene group and a naphthylene group are particularly preferable from the viewpoint of production cost. Further, when a phenylene group and a naphthylene group are compared, a phenylene group is more preferable in terms of ease of synthesis in addition to manufacturing cost.

Moreover, the arylene group which comprises Ar < ¹ > -Ar < ⁴ > may have a substituent each independently. Specific examples of the substituent include an alkyl group, an aryl group, a halogen group, an alkoxy group, and a condensed polycyclic group. Of these, considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer, the aryl group is preferably a phenyl group, a naphthyl group, etc., and the halogen group is a fluorine atom, chlorine An atom, a bromine atom, an iodine atom and the like are preferable, and examples of the alkoxy group include a methoxy group, an ethoxy group and a butoxy group. In addition, when the substituent is an alkyl group, the carbon number of the alkyl group is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 2 or less, and specifically, a methyl group is particularly preferred. . Moreover, there is no restriction | limiting in particular in the number of each substituent of Ar < ¹ > -Ar < ⁴ >, Preferably it is 3 or less, It is more preferable that it is 2 or less, It is especially preferable that it is 1 or less.

Further, in the formula (1), when Ar ¹ and Ar ² have a substituent, Ar ¹ and Ar ² are preferably the same arylene group having the same substituent, and phenylene having a methyl group as a substituent. More preferably, it is a group. Ar ³ and Ar ⁴ are preferably the same arylene group, and particularly preferably a phenylene group having no substituent.

In the formula (1), X ¹ represents a single bond or a divalent group. Preferable examples of X ¹ include a sulfur atom, an oxygen atom, a sulfonyl group, a cycloalkylene group, —CR ² R ³ — and the like. Here, R ² and R ³ each independently represent a hydrogen atom, an alkyl group, an aryl group, a halogen group, or an alkoxy group. Of R ² and R ³ , the aryl group is preferably a phenyl group, a naphthyl group, etc., considering the mechanical properties as a binder resin for the photosensitive layer and the solubility in the coating solution for forming the photosensitive layer. As the halogen group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like are preferable, and as the alkoxy group, a methoxy group, an ethoxy group, a butoxy group and the like are preferably exemplified. When R ² or R ³ is an alkyl group, the alkyl group usually has 1 or more carbon atoms, usually 10 or less, preferably 8 or less, more preferably 2 or less.

Further, considering the simplicity of production of the divalent hydroxy compound used in producing the polyester resin according to the present invention, examples of preferable groups as X ¹ include —O—, —S—, —SO—, _{-SO 2 -, - CO -,} - CH 2 -, - CH (CH 3) -, - C (CH 3) 2 -, include cyclohexylidene. Among these, —CH ₂ —, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, and cyclohexylidene are preferable, and —CH ₂ —, —CH (CH ₃ ) —, cyclohexylene are particularly preferable. Den.

（式（３），（４）において、Ａｒ¹〜Ａｒ⁴は、それぞれ独立に、置換基を有していてもよいアリーレン基を表わし、Ｘ¹は単結合または二価基を表わす。） By the way, the repeating structure represented by the above formula (1) is represented by a divalent hydroxy residue (partial structure represented by the following formula (3)) and a dicarboxylic acid residue (the following formula (4)). Partial structure). The structures of these divalent hydroxy residues and dicarboxylic acid residues have various effects on the polyester resin according to the present invention. Therefore, it is desirable that the structures of the divalent hydroxy residue and the dicarboxylic acid residue are appropriately preferred.

(In formulas (3) and (4), Ar ^{1 to} Ar ⁴ each independently represent an arylene group which may have a substituent, and X ¹ represents a single bond or a divalent group.)

Hereinafter, preferred structures of the above divalent hydroxy residue and dicarboxylic acid residue will be described.
First, the divalent hydroxy residue is represented by the formula (3). In the formula (3), Ar ¹ , Ar ² and X ¹ are the same as those described in the formula (1).

（式（５）中、Ａｒ⁵、Ａｒ⁶は、それぞれ独立に、置換基を有していてもよいフェニレン基を表わし、Ｒ¹は水素原子またはメチル基を表わす。） Among the divalent hydroxy residues represented by the above formula (3), a divalent phenol residue represented by the following formula (5) is particularly preferable.

(In Formula (5), Ar ⁵ and Ar ⁶ each independently represent a phenylene group which may have a substituent, and R ¹ represents a hydrogen atom or a methyl group.)

In the formula (5), Ar ⁵ and Ar ⁶ each independently represent a phenylene group which may have a substituent. At this time, the substituents of Ar ⁵ and Ar ⁶ are the same as those described above as the substituents of Ar ^{1 to} Ar ⁴ .
In the formula (5), R ¹ represents a hydrogen atom or a methyl group.

Specific examples of the formula (5) include divalent phenol residues having a structure in which a hydrogen atom is removed from the hydroxyl group of the divalent phenol compound exemplified below.
That is, when R ¹ is a hydrogen atom, examples of the dihydric phenol compound corresponding to the dihydric phenol residue represented by the formula (5) include bis (2-hydroxyphenyl) methane, (2-hydroxyphenyl). ) (3-hydroxyphenyl) methane, (2-hydroxyphenyl) (4-hydroxyphenyl) methane, bis (3-hydroxyphenyl) methane, (3-hydroxyphenyl) (4-hydroxyphenyl) methane, bis (4- Hydroxyphenyl) methane, bis (2-hydroxy-3-methylphenyl) methane, bis (2-hydroxy-3-ethylphenyl) methane, (2-hydroxy-3-methylphenyl) (3-hydroxy-4-methylphenyl) ) Methane, (2-hydroxy-3-ethylphenyl) (3-hydroxy-4-ethylphenyl) Tan, (2-hydroxy-3-methylphenyl) (4-hydroxy-3-methylphenyl) methane, (2-hydroxy-3-ethylphenyl) (4-hydroxy-3-ethylphenyl) methane, bis (3- Hydroxy-4-methylphenyl) methane, bis (3-hydroxy-4-ethylphenyl) methane, (3-hydroxy-4-methylphenyl) (4-hydroxy-3-methylphenyl) methane, (3-hydroxy-4 -Ethylphenyl) (4-hydroxy-3-ethylphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, bis (4-hydroxy-3-ethylphenyl) methane, bis (4-hydroxy-3, 5-dimethylphenyl) methane, (4-hydroxy-3,5-dimethylphenyl) (3-hydroxy-2,4 -Dimethylphenyl) methane, bis (3-hydroxy-2,4-dimethylphenyl) methane, and the like.

When R ¹ is a methyl group, examples of the dihydric phenol compound corresponding to the dihydric phenol residue represented by the formula (5) include 1,1-bis (2-hydroxyphenyl) ethane, 1- (2-hydroxyphenyl) -1- (3-hydroxyphenyl) ethane, 1- (2-hydroxyphenyl) -1- (4-hydroxyphenyl) ethane, 1,1-bis (3-hydroxyphenyl) ethane 1- (3-hydroxyphenyl) -1- (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (2-hydroxy-3-methylphenyl) ethane, 1,1-bis (2-hydroxy-3-ethylphenyl) ethane, 1- (2-hydroxy-3-methylphenyl) -1- (3-hydroxy-4-methylphenyl) ethane 1- (2-hydroxy-3-ethylphenyl) -1- (3-hydroxy-4-ethylphenyl) ethane, 1- (2-hydroxy-3-methylphenyl) -1- (4-hydroxy-3) -Methylphenyl) ethane, 1- (2-hydroxy-3-ethylphenyl) -1- (4-hydroxy-3-ethylphenyl) ethane, 1,1-bis (3-hydroxy-4-methylphenyl) ethane, 1,1-bis (3-hydroxy-4-ethylphenyl) ethane, 1- (3-hydroxy-4-methylphenyl) -1- (4-hydroxy-3-methylphenyl) ethane, 1- (3-hydroxy -4-ethylphenyl) -1- (4-hydroxy-3-ethylphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) ethane, 1,1-bis (4- Hydroxy-3-ethylphenyl) ethane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) ethane, 1- (4-hydroxy-3,5-dimethylphenyl) -1- (3-hydroxy- 2,4-dimethylphenyl) ethane, 1,1-bis (3-hydroxy-2,4-dimethylphenyl) ethane, and the like.

Among these, considering the simplicity of production of the dihydric phenol compound, when R ¹ is a hydrogen atom, bis (4-hydroxyphenyl) methane, (2-hydroxyphenyl) (4-hydroxyphenyl) methane, bis ( 2-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, bis (4-hydroxy-3-ethylphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) methane are particularly preferred. . When R ¹ is a methyl group, 1,1-bis (4-hydroxyphenyl) ethane, 1- (2-hydroxyphenyl) -1- (4-hydroxyphenyl) ethane, 1,1-bis ( 2-hydroxyphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) ethane, 1,1-bis (4-hydroxy-3-ethylphenyl) ethane, 1,1-bis (4-hydroxy) -3,5-dimethylphenyl) ethane and the like are preferred.

  Further, in the formula (3), when an example of a divalent hydroxy residue not included in the formula (5) is given, divalent hydroxy having a structure in which a hydrogen atom is removed from the hydroxyl group of the divalent hydroxy compound exemplified below. Residue.

  That is, examples of the divalent hydroxy compound corresponding to the divalent hydroxy residue represented by the formula (3) include 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl, 2 , 4,3 ′, 5′-tetramethyl-3,4′-dihydroxybiphenyl, 2,2 ′, 4,4′-tetramethyl-3,3′-dihydroxybiphenyl,

1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2 -(4-hydroxy-3,5-dimethylphenyl) -2- (3-hydroxy-2,4-dimethylphenyl) propane, 1,1-bis (3-hydroxy-2,4-dimethylphenyl) propane, 2 , 2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2- (4-hydroxy-3,5-dimethylphenyl) -2- (3-hydroxy-2,4-dimethylphenyl) propane, 2,2-bis (3-hydroxy-2,4 Dimethylphenyl) propane,

Bis- (4-hydroxyphenyl) phenylmethane, 1,1-bis- (4-hydroxyphenyl) -1-phenylethane, 1,1-bis- (4-hydroxyphenyl) -1-phenylpropane, bis- ( 4-hydroxyphenyl) diphenylmethane, bis- (4-hydroxyphenyl) dibenzylmethane,

1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) cyclohexane, -(4-hydroxy-3,5-dimethylphenyl) -1- (3-hydroxy-2,4-dimethylphenyl) cyclohexane, 1,1-bis (3-hydroxy-2,4-dimethylphenyl) cyclohexane,

Bis (2-hydroxyphenyl) ether, (2-hydroxyphenyl) (3-hydroxyphenyl) ether, (2-hydroxyphenyl) (4-hydroxyphenyl) ether, bis (3-hydroxyphenyl) ether, (3-hydroxy Phenyl) (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ether, bis (2-hydroxy-3-methylphenyl) ether, bis (2-hydroxy-3-ethylphenyl) ether, (2-hydroxy- 3-methylphenyl) (3-hydroxy-4-methylphenyl) ether, (2-hydroxy-3-ethylphenyl) (3-hydroxy-4-ethylphenyl) ether, (2-hydroxy-3-methylphenyl) ( 4-hydroxy-3-methylphenyl) ether (2-hydroxy-3-ethylphenyl) (4-hydroxy-3-ethylphenyl) ether, bis (3-hydroxy-4-methylphenyl) ether, bis (3-hydroxy-4-ethylphenyl) ether, (3 -Hydroxy-4-methylphenyl) (4-hydroxy-3-methylphenyl) ether, (3-hydroxy-4-ethylphenyl) (4-hydroxy-3-ethylphenyl) ether, bis (4-hydroxy-3- Methylphenyl) ether, bis (4-hydroxy-3-ethylphenyl) ether, bis (4-hydroxy-3,5-dimethylphenyl) ether, (4-hydroxy-3,5-dimethylphenyl) (3-hydroxy- 2,4-dimethylphenyl) ether, bis (3-hydroxy-2,4-dimethylphenol Le) ether,

Bis (4-hydroxyphenyl) ketone, etc. are mentioned.

  Among these, considering the simplicity of production of the divalent hydroxy compound, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxy-3) , 5-dimethylphenyl) propane, 1,1-bis (4-hydroxy-3,5-dimethylphenyl) cyclohexane, or bis (4-hydroxyphenyl) ether, (2-hydroxyphenyl) (4-hydroxyphenyl) Ether, bis (2-hydroxyphenyl) ether, bis (4-hydroxy-3-methylphenyl) ether, bis (4-hydroxy-3-ethylphenyl) ether, bis (4-hydroxy-3,5-dimethylphenyl) Ether, etc. are preferred.

  In addition, the bivalent hydroxy compound and divalent hydroxy residue mentioned above may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

On the other hand, the dicarboxylic acid residue is represented by the formula (4). In the formula (4), Ar ³ and Ar ⁴ are the same as those described in the formula (1). Specific examples of the dicarboxylic acid residue having the structure represented by the above formula (4) include dicarboxylic acid residues having a structure in which the hydroxyl group is removed from the carboxyl group of the dicarboxylic acid compound exemplified below.
That is, for example, examples of the dicarboxylic acid compound corresponding to the dicarboxylic acid residue represented by the formula (4) include diphenyl ether-2,2′-dicarboxylic acid, diphenyl ether-2,3′-dicarboxylic acid, diphenyl ether- Examples include 2,4′-dicarboxylic acid, diphenyl ether-3,3′-dicarboxylic acid, diphenyl ether-3,4′-dicarboxylic acid, diphenyl ether-4,4′-dicarboxylic acid. Among these, diphenyl ether-2,2′-dicarboxylic acid, diphenyl ether-2,4′-dicarboxylic acid, and diphenyl ether-4,4′-dicarboxylic acid are preferable, considering the simplicity of production of the dicarboxylic acid compound. -4,4'-dicarboxylic acid is particularly preferred.
In addition, the dicarboxylic acid compound and dicarboxylic acid residue mentioned above may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

（式（２）中、Ａｒ⁵〜Ａｒ⁸は、それぞれ独立に、置換基を有していてもよいフェニレン基を表わし、Ｒ¹は水素原子またはメチル基を表わす。） Therefore, it is preferable to appropriately select the aforementioned Ar ^{1 to} Ar ⁴ and X ¹ so that the structure of the divalent hydroxy residue and the dicarboxylic acid residue is the preferable structure.
From the above points, among the polyester resins according to the present invention described above, those including a repeating structure represented by the following formula (2) are particularly preferable.

(In formula (2), Ar ^{5 to} Ar ⁸ each independently represents a phenylene group which may have a substituent, and R ¹ represents a hydrogen atom or a methyl group.)

In the formula (2), Ar ⁵ , Ar ⁶ and R ¹ are the same as those described in the formula (5).
In the formula (2), Ar ⁷ and Ar ⁸ each independently represent a phenylene group which may have a substituent. At this time, the substituents of Ar ⁷ and Ar ⁸ are the same as those described above as the substituents of Ar ^{1 to} Ar ⁴ .

Moreover, the repeating structure represented by the formula (1) may be one kind in the polyester resin according to the present invention, or two or more kinds may be used in any combination and ratio. Therefore, the above divalent hydroxy residue and dicarboxylic acid residue may be used alone or in combination of two or more in any combination and ratio. Ar ^{1 to} Ar ⁴ and X ¹ may each be used alone or in combination of two or more in any combination and ratio.

  Furthermore, the polyester resin according to the present invention may contain a component other than the divalent hydroxy residue represented by the above formula (3) or the dicarboxylic acid residue represented by the formula (4) as its partial structure. . For example, a resin that includes another dicarboxylic acid residue of the dicarboxylic acid residue represented by the formula (4) and includes the repeating structure of the formula (1) in a part of the structure may be used. Specific examples of other dicarboxylic acid residues include adipic acid residues, suberic acid residues, sebacic acid residues, phthalic acid residues, isophthalic acid residues, terephthalic acid residues, toluene-2,5-dicarboxylic acid Residue, p-xylene-2,5-dicarboxylic acid residue, pyridine-2,3-dicarboxylic acid residue, pyridine-2,4-dicarboxylic acid residue, pyridine-2,5-dicarboxylic acid residue, pyridine -2,6-dicarboxylic acid residue, pyridine-3,4-dicarboxylic acid residue, pyridine-3,5-dicarboxylic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,3-dicarboxylic acid Examples include acid residues, naphthalene-2,6-dicarboxylic acid residues, biphenyl-2,2′-dicarboxylic acid residues, biphenyl-4,4′-dicarboxylic acid residues and the like. Among these, preferably, adipic acid residue, sebacic acid residue, phthalic acid residue, isophthalic acid residue, terephthalic acid residue, naphthalene-1,4-dicarboxylic acid residue, naphthalene-2,6-dicarboxylic acid residue Group, biphenyl-2,2′-dicarboxylic acid residue, biphenyl-4,4′-dicarboxylic acid residue, and particularly preferred are isophthalic acid residue and terephthalic acid residue. In addition, as for the repeating unit (residue) other than the divalent hydroxy residue represented by the above formula (3) or the dicarboxylic acid residue represented by the formula (4), one type may be used alone, or two types may be used. The above may be used in any combination and ratio.

  However, in the polyester resin according to the present invention, it is preferable that the number of repeating units other than the divalent hydroxy residue represented by the formula (3) or the dicarboxylic acid residue represented by the formula (4) is small. Therefore, it is preferable that the amount of divalent hydroxy residues other than those represented by formula (3) and dicarboxylic acid residues other than those represented by formula (4) is also small. Although the specific ratio is not limited, for example, for the dicarboxylic acid residue, the ratio of the dicarboxylic acid residue represented by the formula (4) in the total amount of the dicarboxylic acid residue is usually 70 by the ratio of the number of repeating units. % Or more, preferably 80% or more, more preferably 90% or more, and particularly preferably 100%.

  Next, the manufacturing method of the polyester resin concerning this invention is demonstrated. As a method for producing the polyester resin according to the present invention, a known polymerization method can be used. Examples thereof include an interfacial polymerization method, a melt polymerization method, and a solution polymerization method.

  For example, in the case of production by the interfacial polymerization method, a solution in which a divalent hydroxy compound is dissolved in an alkaline aqueous solution and a halogenated hydrocarbon solution in which an aromatic dicarboxylic acid chloride is dissolved are mixed. At this time, a quaternary ammonium salt or a quaternary phosphonium salt may be present as a catalyst. The polymerization temperature is preferably in the range of 0 to 40 ° C., and the polymerization time is preferably in the range of 2 to 20 hours from the viewpoint of productivity. After 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, whereby the intended resin can be obtained.

  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, the range of 1.01-3 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. In addition, a halogenated hydrocarbon may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, 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, benzyl Trimethylammonium chloride, benzyltributylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, trioctylmethylammonium chloride, tetrabutylphosphonium bromide, triethyloctadecylphosphonium bromide, N-laurylpyridinium chloride, laurylpicolinium chloride, etc. Is mentioned. In addition, a catalyst may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and ratios.

  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. Phenol, hexylphenol, octylphenol, nonylphenol, alkylphenols such as 2,6-dimethylphenol derivatives and 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. Particularly preferred are p- (tert-butyl) phenol, 2,3,6-tetramethylphenol, and 2,3,5-tetramethylphenol. In addition, a molecular weight regulator may also be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

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

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

  Moreover, although the usage rate of the resin used together is not specifically limited, In order to fully acquire the effect of this invention, it is preferable to use together in the range which does not exceed the ratio of the polyester resin concerning this invention. In particular, it is preferable not to use other resins in combination.

[I-2. Antioxidant]
As the antioxidant, known ones can be arbitrarily used. For example, radical chain reaction inhibitors such as phenol-based antioxidants and amine-based antioxidants; chain reaction initiation inhibitors such as UV absorbers, light stabilizers, metal deactivators, and ozone degradation inhibitors; sulfur-based oxidation Examples thereof include peroxide decomposers such as inhibitors and phosphorus antioxidants.

  The radical chain reaction inhibitor has a function of stopping radical chain reaction by capturing radicals generated by the influence of heat, light, gas, etc. on the photoreceptor. The chain reaction initiation inhibitor has a function of suppressing a chain initiation reaction caused by factors such as light and heat. The peroxide decomposing agent has a function of breaking the contribution to the chain reaction by decomposing peroxide (peroxide) resulting from ozone generated during charging into an inactive compound.

  Among the radical chain reaction inhibitors, examples of the phenolic antioxidant include 3,5-di-t-butyl-4-hydroxytoluene, 2,6-di-t-butylphenol, and 2,6-di- t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-methylphenol, 2,2'-methylenebis (6-t-butyl-4-methylphenol), 4,4'-butylidenebis ( 6-t-butyl-3-methylphenol), 4,4'-thiobis (6-t-butyl-3-methylphenol), 2,2'-butylidenebis (6-t-butyl-4-methylphenol), α-tocopherol, β-tocopherol, 2,2,4-trimethyl-6-hydroxy-7-t-butylchroman, pentaerythrityltetrakis [3- (3,5-di-t-butyl-4- Hydroxyphenyl) propionate], 2,2′-thioethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,6-hexanediol bis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], butylhydroxyanisole, dibutylhydroxyanisole, 1- [2-{(3,5-di-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4 -[3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperazyl, 2,4-bis- (n-octylthio) -6- ( 4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 1,3,5-trimethyl-2,4,6-tris (3 5-di-t-butyl-4-hydroxybenzyl) benzene, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5 -Chlorobenzotriazole, 1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-t-butyl) -4-hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, etc. Can do.

  Among these, those having one or more t-butyl groups on the phenol ring in the molecule are preferable, and among them, those in which the t-butyl group is bonded to the position adjacent to the phenolic hydroxyl group are more preferable. Specific examples thereof include 3,5-di-t-butyl-4-hydroxytoluene, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6 Monophenolic antioxidants such as di-t-butyl-4-methylphenol and n-octadecyl-3- (4'-hydroxy-3 ', 5'-di-t-butylphenyl) propionate; '-Methylenebis (6-tert-butyl-4-methylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, penta A polyphenol antioxidant such as erythrityltetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is suitable.

  In addition, as the radical chain reaction inhibitor, for example, hydroquinones can be used. Specific examples thereof include 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) -5-methylhydroquinone and the like can be mentioned. Examples of amine-based antioxidants include phenyl-β-naphthylamine, α-naphthylamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine, and tribenzylamine.

  Furthermore, among these, 3,5-di-t-butyl-4-hydroxytoluene, n-octadecyl-3- (4'-hydroxy-3 ', 5'-di-t-butylphenyl) propionate, 1, 3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene is particularly preferred in terms of electrical properties.

  Furthermore, among the chain reaction initiation inhibitors, examples of the ultraviolet absorber and light stabilizer include phenyl salicylate, monoglycol salicylate, 2-hydroxy-4-methoxybenzophenone, 2- (2′-hydroxy). -5'-methylphenyl) benzotriazole, resorcinol monobenzoate and the like. Examples of the metal deactivator include N-salicyloyl-N′-aldehyde hydrazine, N, N′-diphenyloxamide and the like. Furthermore, examples of the ozone deterioration preventing agent include 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-N′-isopropyl-p-phenylenediamine, and the like.

  Among the peroxide decomposers, examples of the sulfur-based antioxidant include dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, and ditetradecyl-3,3. Examples include '-thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl thiodipropionate, and 2-mercaptobenzimidazole. Further, phosphorus antioxidants include, for example, triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, tridecyl Examples include phosphine and trioctadecylphosphine.

Of these antioxidants, phenolic antioxidants are particularly preferred. This is because the stability of the coating solution can be increased. Among them, 3,5-di-t-butyl-4-hydroxytoluene, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2, 4,6-Tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene is good.
In addition, antioxidant may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Moreover, the usage-amount of antioxidant is arbitrary unless the effect of this invention is impaired remarkably. However, the antioxidant is usually 0.01 parts by weight or more, preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and usually 100 parts by weight or less with respect to 100 parts by weight of the binder resin. , Preferably 30 parts by weight or less, more preferably 16 parts by weight or less. If the upper limit of this range is exceeded, electrical characteristics may be deteriorated, and if the lower limit is not reached, the effects of the present invention may not be sufficiently obtained.

[I-3. solvent]
The coating liquid of the present invention usually contains a solvent. The polyester resin and the antioxidant according to the present invention are present in a state of being dissolved or dispersed in a solvent in the coating liquid of the present invention. Especially, it is preferable that the polyester resin and antioxidant concerning this invention exist in the state melt | dissolved in the solvent.

There is no restriction | limiting in particular in the kind of solvent, Arbitrary things can be used in the range which does not impair the effect of this invention remarkably, if the polyester resin concerning this invention and antioxidant are dissolved or disperse | distributed. For example, alcohols such as methanol, ethanol, propanol and 2-methoxyethanol; ethers such as tetrahydrofuran, 1,4-dioxane and dimethoxyethane; esters such as methyl formate and ethyl acetate; acetone, methyl ethyl ketone and cyclohexanone Ketones; aromatic hydrocarbons such as benzene, toluene, xylene; dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-di Chlorinated hydrocarbons such as chloropropane and trichloroethylene; nitrogen-containing compounds such as n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine and triethylenediamine; acetonitrile, N- Methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like.
In addition, a solvent may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Moreover, when using a solvent, there is no restriction | limiting in the usage-amount. However, when the coating solution of the present invention is used for forming a photosensitive layer of a single layer type photoreceptor or a charge transport layer of a laminated type photoreceptor, the solid content concentration of the coating solution is usually 10% by weight or more, preferably 15%. It is desirable to adjust the amount of solvent used so that it is in the range of not less than wt%, usually not more than 40 wt%, preferably not more than 35 wt%. In order to keep the coating property of the coating solution good, the viscosity of the coating solution of the present invention is usually 50 mPa · s or more, preferably 100 mPa · s or more, and usually 1000 mPa · s or less, preferably 600 mPa · s. It is desirable to adjust the composition and use amount of the solvent so as to be in the following range.

  Further, when the coating solution of the present invention is used for forming the charge generating layer of the multilayer photoreceptor, the solid content concentration of the coating solution is usually 1% by weight or more, preferably 2% by weight or more, and usually 15% by weight. It is desirable to adjust the amount of the solvent used so that it is in the range of not more than%, preferably not more than 10% by weight. In order to keep the coating property of the coating solution good, the viscosity of the coating solution of the present invention is usually 0.1 mPa · s or more, preferably 0.5 mPa · s or more, and usually 10 mPa · s or less, preferably It is desirable to adjust the composition and use amount of the solvent so that is in the range of 8 mPa · s or less.

[I-4. Charge generation material]
When the coating solution of the present invention is used for a photosensitive layer of a single layer type photoreceptor or a charge generation layer of a laminated type photoreceptor, the coating solution of the present invention usually contains a charge generation material. This charge generation material is a material contained in the charge generation layer of the single layer type photoreceptor or the multilayer type photoreceptor when the photosensitive layer is formed.

  Examples of charge generation materials include selenium and its alloys, cadmium sulfide, and other inorganic photoconductive materials; phthalocyanine pigments, azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, benzimidazole pigments Various photoconductive materials such as organic pigments; Among these, organic pigments are particularly preferable, and phthalocyanine pigments and azo pigments are more preferable.

  In particular, when a phthalocyanine compound is used as the charge generation material, specifically, a metal such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, or an oxide or halide thereof. Coordinated phthalocyanines are used. Examples of the ligand to the trivalent or higher metal atom include a hydroxyl group and an alkoxy group in addition to the oxygen atom and chlorine atom shown above. Among them, particularly sensitive X-type, τ-type metal-free phthalocyanine, A-type, B-type, D-type titanyl phthalocyanine, vanadyl phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, and the like are preferable.

  Of the crystal forms of titanyl phthalocyanine mentioned here, A type and B type are described in W.W. It has been shown by Heller et al. As phase I and phase II (Zeit. Kristallogr. 159 (1982) 173), respectively, and type A is known as a stable type. The D-type is a crystal type characterized by a clear peak at a diffraction angle 2θ ± 0.2 ° of 27.3 ° in powder X-ray diffraction using CuKα rays.

  In addition, the charge generation material may be used alone or in combination of two or more in any combination and ratio. Furthermore, when two or more charge generation materials are used in combination, the charge generation material used in combination and the mixed state in the crystalline state may be used by mixing the respective constituent elements later, or synthesis, pigmentation Alternatively, a mixed state may be generated and used in the charge generation material production / treatment process such as crystallization. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known.

  In particular, in the photosensitive layer of a single-layer type photoreceptor, it is desirable that the particle size of the charge generating material is sufficiently small. Specifically, it is usually 1 μm or less, preferably 0.5 μm or less.

  Furthermore, the content of the charge generating substance in the coating solution of the present invention is arbitrary as long as the effects of the present invention are not significantly impaired. However, when the coating solution of the present invention is used for the charge generation layer of the multilayer photoreceptor, the amount of the charge generating substance in the coating solution of the present invention is the binder resin in the coating solution of the present invention (that is, the present invention). The total amount of polyester resin and other resin is 100 parts by weight, usually 30 parts by weight or more, preferably 50 parts by weight or more, more preferably 100 parts by weight or more, and usually 500 parts by weight or less, preferably It is desirable that the amount be 300 parts by weight or less, more preferably 200 parts by weight or less. If the amount of the charge generating material is too small, sufficient sensitivity may not be obtained. If the amount is too large, the photosensitive member may be deteriorated in chargeability and sensitivity.

  Further, when used for a photosensitive layer of a single-layer type photoreceptor, the amount of the charge generating substance in the coating solution of the present invention is usually 0.5% by weight or more, preferably the amount of the charge generating substance in the photosensitive layer. It is desirable to prepare such that it is 1% by weight or more, and usually 50% by weight or less, preferably 20% by weight or less. This is because if the amount of the charge generating substance is too small, sufficient sensitivity may not be obtained, and if the amount is too large, the photoreceptor may be deteriorated in chargeability and sensitivity.

[I-5. Charge transport material]
When the coating solution of the present invention is used for a photosensitive layer of a single layer type photoreceptor or a charge transport layer of a laminated type photoreceptor, the coating solution of the present invention usually contains a charge transport material. This charge transport material is a material contained in the charge transport layer of the single layer type photoreceptor or the multilayer photoreceptor when the photosensitive layer is formed.

  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. Any one of these charge transport materials may be used alone, or two or more thereof may be used in any combination and ratio.

  Specific examples of suitable structures of the charge transport material are shown below. However, these specific examples are shown for illustration, and any known charge transport material may be used as long as it is not contrary to the gist of the present invention. “T-Bu” represents a t-butyl group.

  Furthermore, the content of the charge transport material in the coating solution of the present invention is arbitrary as long as the effects of the present invention are not significantly impaired. However, the amount of the charge transport material in the coating solution of the present invention is the same as that of the coating solution of the present invention, regardless of whether the coating solution of the present invention is used for either the photosensitive layer of the single-layer type photoreceptor or the charge transport layer of the multilayer type photoreceptor. Usually 30 parts by weight or more, preferably 40 parts by weight or more, more preferably 50 parts by weight or more with respect to 100 parts by weight of the binder resin in the liquid (that is, the total of the polyester resin and other resins according to the present invention). Further, it is usually 200 parts by weight or less, preferably 150 parts by weight or less, more preferably 100 parts by weight or less. If the amount of the charge transport material is too small, the electrical characteristics may be deteriorated. If the amount is too large, the coating film becomes brittle and the wear resistance may be deteriorated.

[I-6. Additives etc.]
The coating liquid of the present invention may appropriately contain components other than those described above.
For example, the coating liquid of the present invention may contain a known additive. These additives are used for improving the film formability, flexibility, coatability, stain resistance, gas resistance, light resistance, mechanical strength and the like of the photosensitive layer. Examples of additives include plasticizers, ultraviolet absorbers, electron withdrawing compounds, dyes, pigments and the like. In particular, examples of dyes and pigments include various pigment compounds and azo compounds. In addition, residual potential inhibitors for suppressing residual potential, dispersion aids for improving dispersion stability, leveling agents (for example, silicone oil, fluorine-based oil, etc.) for improving coating properties, surfactants Etc. can also be used as additives.
In addition, an additive may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[I-7. Application method]
When the coating solution of the present invention is coated on a conductive support to form a layer such as a photosensitive layer, a charge generation layer, or a charge transport layer, there is no limitation on the coating method of the coating solution of the present invention. Therefore, any coating method can be adopted when coating the coating liquid of the present invention. Examples of coating methods include dip coating, spray coating, nozzle coating, bar coating, roll coating, blade coating, and the like. Among these, the dip coating method is preferable because of its high productivity. Note that these coating methods may be performed by only one method, or may be performed by combining two or more methods.

[I-8. Advantages of coating liquid of the present invention]
The coating liquid of the present invention has stable electrical characteristics over time. That is, even after a lapse of time after preparation, the electrical characteristics of the resulting photosensitive layer are unlikely to deteriorate. This effect is particularly remarkable when the coating solution containing the charge transport material contains an antioxidant. This advantage is presumed to be due to the fact that the structure of the present invention suppresses the decomposition of the charge transport material.

Further, the coating liquid of the present invention is stable in liquidity over time. That is, even if time elapses, the liquid state hardly changes due to the generation of precipitates and gels. The liquid property of the coating liquid can be evaluated by the change in viscosity over time. The smaller the change in the viscosity of the coating liquid with time (for example, when the viscosity change rate after 3 months is 10% or less) It can be said that it is stable over time.
In addition, by forming a photosensitive layer using the coating solution of the present invention, a photoreceptor having a photosensitive layer excellent in electrical characteristics and abrasion resistance can be obtained.

[II. Electrophotographic photoreceptor]
The photoreceptor has a photosensitive layer on a conductive support. In the present invention, the photosensitive layer contains the polyester resin and the antioxidant according to the present invention. The polyester resin according to the present invention functions as a binder resin in the photosensitive layer, and the antioxidant functions as an additive in the photosensitive layer.

  As described above, the photosensitive layer type includes a single layer type and a laminated type, and the laminated type photosensitive layer includes a charge generation layer and a charge transport layer. Here, when the photosensitive layer is composed of two or more layers (for example, a charge generation layer and a charge transport layer), the polyester resin and the antioxidant according to the present invention are at least one of the layers forming the photosensitive layer. Although it may be contained in one layer, it is preferably contained in the charge transport layer of the multilayer photoreceptor. That is, the coating liquid of the present invention described above is preferably used for forming the charge transport layer.

[II-1. Conductive support]
There are no particular restrictions on the conductive support, but for example, metallic materials such as aluminum, aluminum alloy, stainless steel, copper and nickel; conductive powders such as metal, carbon and tin oxide were mixed to impart conductivity. Resin material: Resin, glass, paper, or the like obtained by depositing or coating a conductive material such as aluminum, nickel, ITO (indium-tin oxide) on its surface is mainly used. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
Furthermore, as a form of the conductive support, for example, a drum shape, a sheet shape, a belt shape or the like is used. Further, a conductive material having an appropriate resistance value may be coated on a conductive support made of a metal material in order to control conductivity and surface properties or to cover defects.

Further, when a metal material such as an aluminum alloy is used as the conductive support, it may be used after anodizing, chemical conversion coating or the like. When the anodizing treatment is performed, it is desirable to perform a sealing treatment by a known method.
The surface of the support may be smooth, or may be roughened by using a special cutting method or performing a polishing treatment. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the conductive support.

[II-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, a resin in which particles such as metal oxide (usually inorganic particles) are dispersed, or the like is used.

  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 silicone. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. A thing of a several crystalline state may be contained.

  In addition, various particle sizes of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is usually 1 nm or more, preferably 10 nm or more, and usually 100 nm. Below, preferably 50 nm or less.

  The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. Examples of the binder resin used for the undercoat layer include phenoxy, epoxy, polyvinyl pyrrolidone, polyvinyl alcohol, casein, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, and polyamide. Among these, alcohol-soluble copolymerized polyamide, modified polyamide, and the like are preferable because they exhibit good dispersibility and coating properties. The binder resin for the undercoat layer may be used alone or in combination of two or more in any combination and ratio. Furthermore, the binder resin can be used in the form of being cured together with the curing agent, in addition to being used only with the binder resin.

In addition, the use ratio of the particles with respect to the binder resin can be arbitrarily selected, but it is usually preferable in the range of 10% by weight to 500% by weight in view of the stability of the dispersion and the coating property.
Furthermore, the thickness of the undercoat layer is arbitrary as long as the effects of the present invention are not significantly impaired, but from the photoreceptor characteristics and applicability, it is usually preferably from 0.1 μm to 25 μm. Further, the undercoat layer may contain an additive such as an antioxidant.

[II-3. Photosensitive layer]
The photosensitive layer is a layer provided on a conductive support, and the type thereof is a laminated photosensitive layer having a charge generation layer and a charge transport layer, and both the charge transport material and the charge generation material in the same layer. And a single-layer type photosensitive layer. And this photosensitive layer contains the polyester resin and antioxidant concerning this invention.

<Charge generation layer>
The charge generation layer is a layer containing a charge generation material. In the present invention, since the polyester resin and the antioxidant according to the present invention are contained in the photosensitive layer, the polyester resin and the antioxidant according to the present invention may be contained in the charge generation layer.

The charge generating substance is as described above.
In the charge generation layer, the charge generation material is formed in a state where the charge generation material is bound by the binder resin.
At this time, when the charge generation layer contains the polyester resin and the antioxidant according to the present invention, the polyester resin according to the present invention is used as the binder resin. At this time, it is possible to use other binder resins in combination with the polyester resin according to the present invention.

  On the other hand, when the binder resin and the antioxidant according to the present invention are contained in a layer other than the charge generation layer constituting the photosensitive layer (such as a charge transport layer), the polyester according to the present invention is used as the binder resin of the charge generation layer. Only a binder resin other than the resin may be used. Examples of the binder resin used in this case include polyester resin, polyvinyl acetate, polyacrylic acid ester, polymethacrylic acid ester, polyester, polycarbonate, polyvinyl acetoacetal, polyvinyl propional, polyvinyl butyral, phenoxy resin, epoxy resin, and urethane. Examples thereof include resins, cellulose esters, and cellulose ethers. In the charge generation layer, one binder resin may be used alone, or two or more binder resins may be used in any combination and ratio.

The amount of the charge generating material used is arbitrary as long as the effects of the present invention are not significantly impaired. However, it is desirable that the range satisfies the condition of the ratio of the charge generating material to be contained in the coating solution and the binder resin described in the description of the coating solution of the present invention.
Further, the thickness of the charge generation layer is not limited, but is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 1 μm or less, preferably 0.6 μm or less.

Furthermore, when the charge generating layer contains the polyester resin according to the present invention, the charge generating layer preferably contains an antioxidant. Thus, the electrical characteristics of the charge generation layer can be improved by incorporating the polyester resin according to the present invention and the antioxidant in the charge generation layer.
Under the present circumstances, the usage-amount of antioxidant is arbitrary unless the effect of this invention is impaired remarkably. However, it is desirable to make the range satisfying the condition of the ratio of the antioxidant and the binder resin contained in the coating solution mentioned in the description of the coating solution of the present invention.

  The charge generation layer may contain other additives. Even when the charge generating layer does not contain the polyester resin according to the present invention, an antioxidant or other additives may be contained in the charge generating layer.

  The method for forming the charge generation layer is not limited and is arbitrary. For example, a known method such as coating a coating solution obtained by dissolving or dispersing a substance to be contained in the charge generation layer on a conductive support directly or via another layer can be applied. . Therefore, for example, when the charge generation layer contains both the polyester resin and the antioxidant according to the present invention, it can be formed by the following method. That is, a coating solution of the present invention containing a charge generating material, a polyester resin and an antioxidant according to the present invention, and, if necessary, a solvent, an additive and the like is prepared. And the said coating liquid is apply | coated on a conductive support body directly or through another layer. Thereafter, the charge generation layer can be formed by removing the solvent by drying.

<Charge transport layer>
The charge transport layer is a layer containing a charge transport material. Further, in the present invention, the polyester resin and the antioxidant according to the present invention are contained in the photosensitive layer, but the polyester resin and the antioxidant according to the present invention are preferably contained in this charge transport layer.

The charge transport material is as described above.
Further, in the charge transport layer, the charge transport material is formed in a state where the charge transport material is bound by the binder resin.
At this time, when the charge transport layer contains the polyester resin and the antioxidant according to the present invention, the polyester resin according to the present invention is used as the binder resin. At this time, it is possible to use other binder resins in combination with the polyester resin according to the present invention.

On the other hand, when the binder resin and the antioxidant according to the present invention are contained in layers other than the charge transport layer (charge generation layer, etc.) constituting the photosensitive layer, the polyester according to the present invention is used as the binder resin of the charge transport layer. Only a binder resin other than the resin may be used. Examples of the binder resin used in this case include those described above as the binder resin used in combination with the polyester resin according to the present invention.
In the charge transport layer, one type of binder resin may be used alone, or two or more types may be used in any combination and ratio.

The amount of the charge transport material used is arbitrary as long as the effects of the present invention are not significantly impaired. However, it is desirable that the range satisfies the condition of the ratio of the charge transport material and the binder resin contained in the coating solution described in the description of the coating solution of the present invention.
Further, the thickness of the charge transport layer is not limited, but is usually 5 μm or more, preferably 10 μm or more, and usually 50 μm or less, preferably 45 μm or less.

Furthermore, when the charge transport layer contains the polyester resin according to the present invention, the charge transport layer preferably contains an antioxidant. Thus, by incorporating the polyester resin according to the present invention and the antioxidant in combination in the charge transport layer, the electrical characteristics of the charge transport layer can be improved and the wear resistance of the charge transport layer is improved. Can be made. Thereby, it becomes possible to improve the electrical characteristics and abrasion resistance of the photosensitive layer.
Under the present circumstances, the usage-amount of antioxidant is arbitrary unless the effect of this invention is impaired remarkably. However, it is desirable to make the range satisfying the condition of the ratio of the antioxidant and the binder resin contained in the coating solution mentioned in the description of the coating solution of the present invention.

  The charge transport layer may contain other additives in order to improve film forming properties, flexibility, coating properties, contamination resistance, gas resistance, light resistance, and the like. Even when the charge transport layer does not contain the polyester resin according to the present invention, an antioxidant or other additives may be contained in the charge transport layer.

  Furthermore, the charge transport layer may be composed of a single layer, or may be a stack of a plurality of layers having different components or composition ratios. When the charge transport layer is formed from a plurality of layers, it is preferable that at least one layer contains the polyester resin and the antioxidant according to the present invention.

  There is no restriction | limiting in the formation method of a charge transport layer, and it is arbitrary. For example, a known method such as coating a coating solution obtained by dissolving or dispersing a substance to be contained in the charge transport layer on a conductive support directly or via another layer can be applied. . Therefore, for example, when the charge transport layer contains both the polyester resin and the antioxidant according to the present invention, it can be formed by the following method. That is, a coating liquid of the present invention containing a charge transport material, a polyester resin and an antioxidant according to the present invention, and, if necessary, a solvent, an additive and the like is prepared. Then, the coating solution is directly or via other layers on the conductive support (on the charge generation layer in the case of the forward lamination type photosensitive layer, and on the reverse lamination type photosensitive layer). It is applied on a conductive support (on the undercoat layer when an undercoat layer is provided). Thereafter, the charge transport layer can be formed by removing the solvent by drying.

<Single layer type (dispersion type) photosensitive layer>
The single-layer type photosensitive layer is configured by dispersing the above-described charge generating material in the charge transport layer having the above-described mixing ratio. However, the single-layer type photosensitive layer always contains the polyester resin and the antioxidant according to the present invention. Thereby, it becomes possible to improve the electrical characteristics and abrasion resistance of the photosensitive layer.

  In the single-layer type photosensitive layer, the types of charge transport materials, binder resins and antioxidants, and the usage ratios thereof are the same as those in the case of containing the polyester resin and antioxidant of the present invention. This is the same as described above. Therefore, in the single layer type photoreceptor, the polyester resin and the antioxidant according to the present invention are also contained in the photosensitive layer.

Moreover, the kind of charge generation material is as described above. However, in this case, it is desirable that the particle size of the charge generation material is sufficiently small. Specifically, the charge generation material contained in the coating solution described in the description of the coating solution of the present invention is made to fall within a desirable particle size range.
Furthermore, if the amount of the charge generating material dispersed in the photosensitive layer is too small, there is a possibility that sufficient sensitivity cannot be obtained, and if it is too large, there are problems such as a decrease in chargeability and a decrease in sensitivity. Therefore, the amount of the charge generating material in the single-layer type photosensitive layer should be within a range that satisfies the condition of the ratio of the charge generating material to be contained in the coating solution and the binder resin mentioned in the description of the coating solution of the present invention. desirable.

The thickness of the single-layer type photosensitive layer is arbitrary, but is usually 5 μm or more, preferably 10 μm or more, and usually 50 μm or less, preferably 45 μm or less.
Further, in the single-layer type photosensitive layer, an additive other than the antioxidant may be contained in the same manner as the charge generation layer.

  There is no restriction | limiting in the formation method of a single layer type photosensitive layer, and it is arbitrary. For example, a known method such as coating a coating solution obtained by dissolving or dispersing a substance contained in the photosensitive layer in a solvent may be applied directly or via another layer on the conductive support. Therefore, for example, it can be formed by the following method. That is, a coating solution of the present invention containing a charge generating material, a charge transporting material, a polyester resin and an antioxidant according to the present invention, and a solvent, an additive and the like as required is prepared. And the said coating liquid is apply | coated on an electroconductive support body directly or via another layer (when providing an undercoat layer on an undercoat layer). Thereafter, the solvent is removed by drying, whereby a single-layer type photosensitive layer can be formed.

[II-4. Other layers]
In addition to the undercoat layer, the charge generation layer, the charge transport layer, and the single-layer type photosensitive layer, the photoreceptor may further include other layers.
For example, a protective layer may be provided on the photosensitive layer for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to discharge products generated from a charger or the like. In addition, the outermost surface layer may contain, for example, a fluorine resin, a silicone resin, or the like for the purpose of reducing frictional resistance and wear on the surface of the photoreceptor, and further, particles and inorganic compounds made of these resins. Particles may be included.

  There is no restriction | limiting in the formation method of other layers, such as the said protective layer, As long as the effect of this invention is not impaired remarkably, it is arbitrary. For example, 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.

[II-5. effect]
As described above, by incorporating the polyester resin and the antioxidant according to the present invention into the photosensitive layer, it is possible to obtain a photosensitive layer excellent in electrical characteristics and abrasion resistance.
The reason why the above-mentioned advantages can be obtained by combining the polyester resin according to the present invention and the antioxidant into the photosensitive layer is not clear, but is presumed as follows. That is, although the wear resistance is improved by using the polyester resin according to the present invention, it is speculated that the polyester resin according to the present invention may be specifically decomposed. However, since the above-described decomposition is prevented by the antioxidant, it is presumed that the above-described advantages can be obtained by the configuration of the present invention.

  In addition, as described above, when the photosensitive layer is formed in a laminated type, it is preferable that the charge transport layer contains the polyester resin and the antioxidant according to the present invention. This is because the film thickness is often larger than the thickness of the generation layer, so that the effect of containing the polyester resin and the antioxidant can be obtained more remarkably.

  By the way, the photoconductor of the present invention is exposed by writing light from an exposure means to form an electrostatic latent image during image formation. The writing light used at this time is arbitrary as long as an electrostatic latent image can be formed. Among them, monochromatic light having an exposure wavelength of usually 380 nm or more, particularly 400 nm or more, and usually 500 nm or less, particularly 480 nm or less. It is preferable to use it. Thereby, a photoconductor excellent in wear resistance can be exposed with light having a smaller spot size, and a high-quality image having high resolution and high gradation can be formed.

  Considering this point in comparison with the prior art, a photoreceptor using a conventional polyester resin cannot always form an image at an exposure wavelength of 380 nm to 500 nm. For example, a binder resin made of a compound in which a plurality of ester bonds are substituted on one aromatic ring, such as a terephthalic acid residue, and a charge transporting material having a large electron donating property are both for an exposure wavelength of 380 to 500 nm. And had a sufficient transmittance. However, nevertheless, when the charge transport layer is formed by combining both, charge transfer absorption is formed, and thus the charge transport layer has a poor transmittance with respect to an exposure wavelength of 380 to 500 nm. In that respect, the polyester resin of the present invention can also be used in an image forming apparatus having an exposure wavelength of 380 to 500 nm.

[III. Image forming apparatus]
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention (an image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

  As shown in FIG. 1, the image forming apparatus includes an electrophotographic photoreceptor 1, a charging device (charging means) 2, an exposure device (exposure means; image exposure means) 3, and a developing device (developing means) 4. Furthermore, a transfer device (transfer means) 5, a cleaning device (cleaning means) 6, and a fixing device (fixing means) 7 are provided as necessary.

  The electrophotographic photosensitive member 1 is not particularly limited as long as it is the above-described electrophotographic photosensitive member. In FIG. 1, as an example, a drum-shaped photosensitive member in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. Showing the body. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged along the outer peripheral surface of the electrophotographic photoreceptor 1.

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but other corona charging devices such as corotron and scorotron, and contact-type charging devices such as charging brushes are often used.

  In many cases, the electrophotographic photosensitive member 1 and the charging device 2 are cartridges having both of them (the electrophotographic photosensitive member cartridge of the present invention. Designed to be removable from. However, the charging device 2 may be provided separately from the cartridge, for example, in the main body of the image forming apparatus. For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of exposure apparatus 3 is not particularly limited as long as it can form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member 1 by performing exposure (image exposure) on the electrophotographic photosensitive member 1. Absent. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, and LEDs (light emitting diodes). Further, exposure may be performed by a photoreceptor internal exposure method. The light at the time of exposure is arbitrary, but generally monochromatic light is preferable. For example, monochromatic light having a wavelength (exposure wavelength) of 700 nm to 850 nm, monochromatic light having a wavelength of 600 nm to 700 nm and slightly shorter wavelength, wavelength of 300 nm to 500 nm The exposure may be performed with monochromatic light having a short wavelength. Among these, [II-5. As explained in [Effect], it is preferable to perform exposure with monochromatic light having a wavelength of 380 nm to 500 nm.

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

  The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicone resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.

  The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. However, the developing roller 44 and the electrophotographic photosensitive member 1 may not be in contact with each other but may be close to each other. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed of a resin blade such as silicone resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such metal blade with resin. The regulating member 45 normally abuts on the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 0.05 to 5 N / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

  The agitator 42 is provided as necessary, and is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.

  The type of the toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method, or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

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

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

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

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

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

The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.
When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.
After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.

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

  The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.

  The photosensitive member 1 is combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge (electrophotography). The electrophotographic photosensitive member cartridge may be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. For example, at least one of the charging device 2, the exposure device 3, the developing device 4, and the transfer device 5 can be integrally supported together with the photoreceptor 1 to form a cartridge. Also in this case, similarly to the cartridge described in the above embodiment, when the electrophotographic photosensitive member 1 and other members deteriorate, for example, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic image is obtained. By attaching the photosensitive cartridge to the image forming apparatus main body, maintenance and management of the image forming apparatus are facilitated.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the following examples are given for the purpose of illustrating the present invention in detail, and the present invention is not limited to the examples shown below unless it is significantly contrary to the gist thereof. In addition, the description of “parts” in the following Examples, Comparative Examples, and Production Examples indicates “parts by weight” unless otherwise specified.

<Measurement method of viscosity average molecular weight>
First, measurement of the viscosity average molecular weight of the resin will be described.
The resin to be measured is dissolved in dichloromethane to prepare a solution having a concentration C of 6.00 g / L. The flow time t of the sample solution is measured in a constant temperature water bath set to 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 is 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
η = b / a
Mv = 3207 × η ^1.205

<Manufacture of resin>
Hereinafter, the manufacturing method of a polyester resin is demonstrated.
[Production Example 1 (Production of Resin X)]
In a 1000 mL beaker, 23.01 g of sodium hydroxide and 940 mL of H ₂ O were weighed and dissolved while stirring. Thereto, 49.36 g of bis (4-hydroxy-3-methylphenyl) methane (hereinafter referred to as “BP-a” as appropriate) was added, stirred and dissolved, and then the aqueous alkaline solution was transferred to a 2 L reaction vessel. Next, 0.5766 g of benzyltriethylammonium chloride and 1.2955 g of 2,3,5-trimethylphenol were sequentially added to the reaction vessel.

  Next, a mixed solution of 65.27 g of diphenyl ether-4,4′-dicarboxylic acid chloride and 470 mL of dichloromethane was transferred into the dropping funnel. While maintaining the external temperature of the polymerization tank at 20 ° C. and stirring the alkaline aqueous solution in the reaction tank, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 5 hours, 783 mL of dichloromethane was added and stirring was continued for 7 hours.

Thereafter, 8.34 mL of acetic acid was added and stirred for 30 minutes, and then the stirring was stopped and the organic layer was separated. This organic layer was washed twice with 942 mL of 0.1N aqueous sodium hydroxide solution, then twice with 942 mL of 0.1N hydrochloric acid, and further twice with 942 mL of H ₂ O. The washed organic layer was poured into 6266 mL of methanol, and the resulting precipitate was removed by filtration and dried to obtain the desired resin X. It was 51,400 when the viscosity average molecular weight of obtained resin X was measured by said measuring method. The repeating structure of Resin X is shown below.

[Production Example 2 (Production of Resin Y)]
In reaction tank 1, 392 L of demineralized water, 40.58 kg of 25% by weight aqueous sodium hydroxide, 23.01 kg of 1,1-bis (4-hydroxy-3-methylphenyl) ethane (hereinafter referred to as “BP-b” as appropriate) Were added and stirred to prepare an alkaline aqueous solution of BP-b. Thereafter, 0.2552 kg of benzyltriethylammonium chloride and 0.6725 kg of 2,3,5-trimethylphenol were sequentially charged into the reaction vessel.

In addition, 286 kg of dichloromethane and 28.20 kg of diphenyl ether-4,4′-dicarboxylic acid chloride were added to the reaction tank 2 and stirred to prepare a dichloromethane solution of diphenyl ether-4,4′-dicarboxylic acid chloride.
While maintaining the external temperature of the reaction vessel 1 at 20 ° C. and stirring the reaction vessel 1, the dichloromethane solution in the reaction vessel 2 was charged into the reaction vessel 1 over 1 hour. After stirring the reaction vessel 1 for 4 hours, 468 kg of dichloromethane was added and stirring was continued for 8 hours. Thereafter, 3.86 kg of acetic acid was added and stirred for 30 minutes, then stirring was stopped and the organic layer was separated.

  This organic layer was washed with 424 L of a 0.1N aqueous sodium hydroxide solution to separate the organic layer, and then the organic layer was subjected to centrifugal separation to remove water remaining in the organic phase. Again, the obtained organic layer was washed with 424 L of a 0.1N aqueous sodium hydroxide solution, and after separating the organic layer, the organic layer was subjected to centrifugal separation to remove water remaining in the organic phase.

This organic layer was washed four times with 424 L of 0.1N hydrochloric acid, and further washed twice with 424 L of demineralized water, and then the separated organic layer was subjected to centrifugal separation to remove water remaining in the organic layer. The resin dissolved in the organic phase was taken out with a hot water granulator, filtered and dried to obtain 41.7 kg of the desired resin. It was 41,000 when the viscosity average molecular weight of the obtained resin Y was measured by said measuring method. The repeating structure of Resin Y is shown below.

[Production Example 3 (Production of Resin Z)]
In Production Example 2, a resin Z having the same repeating structure as in Production Example 2 was obtained in the same manner as in Production Example 2 except that stirring after adding 468 kg of dichloromethane to reaction vessel 1 was shortened from 8 hours to 6 hours. It was. It was 40,000 when the viscosity average molecular weight of obtained resin Z was measured by said measuring method.

<Manufacture of photoreceptor sheet>
[Example 1]
The undercoat layer dispersion was produced as follows. That is, a rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were flowed at high speed. In a mixed solvent of methanol / 1-propanol in a mixed solvent of methanol / 1-propanol, which was introduced into a mixing kneader (“SMG300” manufactured by Kawata Co., Ltd.) and mixed at a high rotational speed of 34.5 m / sec. Then, a dispersion slurry of hydrophobized titanium oxide was obtained by dispersing with a ball mill. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula (B Compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [in the following formula (E) The compositional molar ratio of the compound represented] is 60% / 15% / 5% / 15% / 5% of the copolymerized polyamide pellets with heating and stirring and mixing to dissolve the polyamide pellets. By performing sonic dispersion treatment, the weight ratio of methanol / 1-propanol / toluene is 7/1/2, and the hydrophobically treated titanium oxide / co-polymer is mixed. Containing a slip polyamide in a weight ratio of 3/1, and a solid concentration of 18.0% of the undercoat layer dispersion.

The undercoat layer-forming coating solution thus obtained was applied onto a polyethylene terephthalate sheet having aluminum deposited on the surface with a wire bar so that the film thickness after drying was 1.2 μm, and dried. Was provided.
Next, 10 parts by weight of oxytitanium phthalocyanine having the powder X-ray diffraction spectrum shown in FIG. In addition to 150 parts by weight of 2-dimethoxyethane, pulverization and dispersion treatment was performed with a sand grind mill to prepare a pigment dispersion. 160 parts by weight of the pigment dispersion thus obtained was added to 100 parts by weight of a 5% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) and an appropriate amount of 1,2-dimethoxy. In addition to ethane, a dispersion having a solid content concentration of 4.0% by weight was finally produced.
The dispersion was applied on the undercoat layer with a wire bar so that the film thickness after drying was 0.4 μm, and then dried to form a charge generation layer.

  Next, 50 parts by weight of a charge transport material (A) comprising a composition of geometric isomer represented by the structure represented by the following formula (A) shown in JP-A-2002-80432, 100 parts by weight of the produced resin X, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate having a structure represented by the following formula (a) as an antioxidant (trade name, manufactured by Ciba Geigy) Irganox 1076) 8 parts by weight and 0.05 part by weight of silicone oil as a leveling agent are mixed with 640 parts by weight of a mixed solvent of tetrahydrofuran and toluene (80% by weight of tetrahydrofuran, 20% by weight of toluene) for forming a charge transport layer. A coating solution A was prepared. At this time, the solubility of the resin in the solvent was good.

  This charge transport layer forming coating solution A 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. Thus, a photoreceptor sheet A1 was produced.

Next, in order to examine the stability of the coating solution, the charge transport layer forming coating solution A was stored at room temperature for 1 month. A photoreceptor sheet A2 was produced in the same manner as the photoreceptor sheet A1, except that the charge transport layer forming coating solution A stored at room temperature for one month was used.
The charge transport layer forming coating solution A was stored at room temperature for an additional 2 months (3 months in total) to prepare a photoreceptor sheet A3 in the same manner.

[Example 2]
The charge transport layer forming coating solution B and the coating solution are the same as in Example 1 except that the resin X used in the charge transport layer forming coating solution A of Example 1 is changed to the resin Y manufactured in Production Example 2. Photosensitive sheet B1 immediately after preparation, photosensitive sheet B2 after one month storage of coating solution at room temperature, and photosensitive sheet B3 after three months storage of coating solution at room temperature were prepared. Also at this time, the solubility of the resin in the solvent was good.

[Example 3]
The charge transport layer forming coating solution C and coating solution were the same as in Example 1 except that the resin X used in the charge transport layer forming coating solution A of Example 1 was changed to the resin Z produced in Production Example 3. A photoreceptor sheet C1 immediately after preparation, a photoreceptor sheet C2 after 1 month storage of the coating solution at room temperature, and a photoreceptor sheet C3 after 3 months storage of the coating solution at room temperature were prepared. Also at this time, the solubility of the resin in the solvent was good.

[Example 4]
Except that the antioxidant used in the coating liquid B for forming a charge transport layer in Example 2 was changed from Irganox 1076 to BHT (3,5-di-t-butyl-4-hydroxytoluene), the same as in Example 2. Then, a charge transport layer forming coating solution D, a photoreceptor sheet D1 immediately after preparation of the coating solution, a photoreceptor sheet D2 after storage of the coating solution at room temperature, and a photoreceptor sheet D3 after storage of the coating solution at room temperature are prepared. did.

[Example 5]
Charge transport was carried out in the same manner as in Example 2 except that the charge transport material used in the coating liquid B for forming a charge transport layer in Example 2 was changed to a compound (B) having a structure represented by the following formula (B). A layer-forming coating solution E, a photoreceptor sheet E1 immediately after preparation of the coating solution, a photoreceptor sheet E2 after storage of the coating solution at room temperature, and a photoreceptor sheet E3 after storage of the coating solution at room temperature were prepared.

[Example 6]
The charge transport layer forming coating solution F and the coating solution were used in the same manner as in Example 5 except that the resin Y used in the charge transport layer forming coating solution E of Example 5 was changed to the resin Z produced in Production Example 3. A photoreceptor sheet F1 immediately after preparation, a photoreceptor sheet F2 after 1 month storage of the coating solution at room temperature, and a photoreceptor sheet F3 after 3 months storage of the coating solution at room temperature were prepared.

[Example 7]
Instead of the charge transport material used in the charge transport layer forming coating solution C of Example 3, 25 parts by weight of a diamine compound (C) having a structure represented by the following formula (C) and the following formula (D): A mixture of 25 parts by weight of the diamine compound (D) having the structure represented by the same procedure as in Example 3 except that a total of 50 parts by weight was used. Photoconductor sheet G1 immediately after, photoconductor sheet G2 after 1 month storage of coating solution at room temperature, and photoconductor sheet G3 after storage of coating solution at room temperature for 3 months were prepared.

[Example 8]
The antioxidant used in the coating liquid B for forming the charge transport layer was changed from Irganox 1076 to 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene. (Hereinafter, sometimes referred to as antioxidant AOX1) In the same manner as in Example 2, the charge transport layer forming coating solution Q, the photoreceptor sheet Q1 immediately after preparation of the coating solution, and the coating solution stored at room temperature. Photosensitive sheet Q2 after one month and photosensitive sheet Q3 after three months of storage of the coating solution at room temperature were prepared.

[Comparative Example 1]
In the charge transport layer forming coating solution B of Example 2, the charge transport layer forming coating solution H and the photoreceptor sheet H1 immediately after preparation of the coating solution were prepared in the same manner as in Example 2 except that the antioxidant Irganox 1076 was not included. Then, a photoreceptor sheet H2 after 1 month storage of the coating solution at room temperature and a photoreceptor H3 after 3 months storage of the coating solution at room temperature were obtained.

[Comparative Example 2]
The charge transport layer forming coating solution C of Example 3 is the same as in Example 3 except that the antioxidant Irganox 1076 is not included, and the charge transport layer forming coating solution I and the photoreceptor sheet I1 immediately after the coating solution is prepared. Then, a photoreceptor sheet I2 after 1 month storage of the coating solution at room temperature and a photoreceptor I3 after 3 months storage of the coating solution at room temperature were obtained.

[Comparative Example 3]
The charge transport layer forming coating solution J of Example 5, except that the antioxidant Irganox 1076 is not included, is the same as in Example 5 except that the charge transport layer forming coating solution J and the photoreceptor sheet J1 immediately after preparation of the coating solution are prepared. Then, a photoreceptor sheet J2 after 1 month storage of the coating solution at room temperature and a photoreceptor J3 after 3 months storage of the coating solution at room temperature were obtained.

[Comparative Example 4]
The charge transport layer forming coating solution F of Example 6 is the same as in Example 6 except that the antioxidant Irganox 1076 is not included, and the charge transport layer forming coating solution K and the photoreceptor sheet K1 immediately after the preparation of the coating solution are prepared. Then, a photoreceptor sheet K2 after 1 month storage of the coating solution at room temperature and a photoreceptor K3 after 3 months storage of the coating solution at room temperature were obtained.

[Comparative Example 5]
The charge transport layer forming coating solution G of Example 7 is the same as in Example 7 except that the antioxidant Irganox 1076 is not included, and the charge transport layer forming coating solution L and the photoreceptor sheet L1 immediately after preparation of the coating solution are prepared. Then, a photoreceptor sheet L2 after 1 month storage of the coating solution at room temperature and a photoreceptor L3 after 3 months storage of the coating solution at room temperature were obtained.

[Comparative Example 6]
Except for using the resin Y used in the charge transport layer forming coating solution B of Example 2 and using the polycarbonate resin W formed of the following repeating structural units, in the same manner as in Example 2, for forming the charge transport layer Coating liquid M, photosensitive sheet M1 immediately after preparation of coating liquid, photosensitive sheet M2 after one month storage of coating liquid at room temperature, and photosensitive sheet M3 after storage of coating liquid at room temperature were prepared. The viscosity average molecular weight of the resin W is 40,000.

[Comparative Example 7]
Except for using polycarbonate resin W instead of resin Y used in charge transport layer forming coating liquid E of Example 5, in the same manner as in Example 5, charge transport layer forming coating liquid N, immediately after preparation of the coating liquid Photoconductor sheet N1, photoconductor sheet N2 after one month of storage of the coating solution at room temperature, and photoconductor sheet N3 after three months of storage of the coating solution at room temperature.

[Comparative Example 8]
The charge transport layer forming coating solution O, immediately after preparation of the coating solution, except that the polycarbonate resin W was used instead of the resin Y used in the charge transport layer forming coating solution H of Comparative Example 1. Photoconductor sheet O1, photoconductor sheet O2 after one month of storage of the coating liquid at room temperature, and photoconductor sheet O3 after three months of storage of the coating liquid at room temperature.

[Comparative Example 9]
The charge transport layer forming coating solution P, immediately after preparation of the coating solution, except that the polycarbonate resin W was used instead of the resin Y used in the charge transport layer forming coating solution J of Comparative Example 3. Photoconductor sheet P1, photoconductor sheet P2 after one month storage of coating solution at room temperature, and photoconductor sheet P3 after three months storage at room temperature of coating solution.

[test]
The produced photoreceptor sheets A1 to P1 were subjected to the following electrical property test and wear test, and only the electrical property tests were conducted for the photoreceptor sheets A2 to P2 and A3 to P3. These results are summarized in Table 1.

<Electrical property test 1>
An electrophotographic characteristic evaluation apparatus manufactured according to the electrophotographic society measurement standard (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405) is used, and the photosensitive sheet is 80 mm in diameter. Attached to an aluminum drum to form a cylindrical shape, the aluminum drum and the aluminum base of the photosensitive sheet are electrically connected, and then the drum is rotated at a constant rotational speed of 60 rpm to perform charging, exposure, potential measurement, and static elimination cycle. An electrical property evaluation test was conducted. At that time, the surface potential after exposure when the photosensitive member is charged so that the initial surface potential becomes −700 V and the light of the halogen lamp is changed to monochromatic light of 780 nm with an interference filter at 0.8 μJ / cm ^2. (Hereinafter sometimes referred to as VL). In the VL measurement, the time required from the exposure to the potential measurement was set to 100 ms, which was a fast response condition. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%.

<Abrasion test>
The photoreceptor sheet was cut into a circle having a diameter of 10 cm, and the wear was evaluated with a Taber abrasion tester (manufactured by Taber). Test conditions were measured by comparing the weight before and after the test with 1000 wheels without load (the weight of the wear wheel) under the atmosphere of 23 ° C. and 50% RH and without wear (self-weight of the wear wheel). did.

  From this result, the photoconductors produced using the photoconductor-forming coating liquids A to G and Q of Examples 1 to 8 exhibit stable electrical characteristics even after 3 months from the preparation of the coating liquid, Moreover, it can be seen that good wear resistance is exhibited. This is considered that the effect is acquired by containing the binder resin of this invention and containing antioxidant in a coating liquid.

  By the way, the photoreceptor produced by the coating liquids M to P for Comparative Examples 6 to 9 using a conventional polycarbonate as the binder resin has stable electrical characteristics over time regardless of the presence or absence of the antioxidant. Although it shows, it is inferior to abrasion resistance. Moreover, when the antioxidant is contained, the electrical characteristics are slightly deteriorated when compared with those not containing the antioxidant.

  On the other hand, the photoconductors produced by the photosensitive layer forming coating liquids H to L of Comparative Examples 1 to 5 containing the polyester resin according to the present invention and containing no antioxidant, have excellent wear resistance, but over time. In addition to the deterioration of the electric characteristics, the initial electric characteristics are deteriorated depending on the kind of the charge transport material as compared with those having the antioxidant. This is presumed that the charge transport material is decomposed both initially and over time due to the influence of residual monomers and the like when the resin is synthesized. This is because the resin Y seems to be more polymerized in the resin Y and the resin Z in which the polymerization conditions of the resin are changed, and the coating solution using the resin Y uses the resin Z. This is consistent with the fact that the degree of deterioration is smaller than that of the coating solution.

  From the above results, the photosensitive layer-forming coating solution containing the polyester resin and the antioxidant according to the present invention exhibits high coating solution stability, and the photoconductor produced using the coating solution has wear resistance and It can be seen that the electrical characteristics are excellent.

[Example 9]
Next, evaluation with a drum-shaped photoreceptor was performed.
The surface of a cylinder made of an aluminum alloy having a mirror-finished outer diameter of 30 mm, length of 375.8 mm, and wall thickness of 1.0 mm is subjected to anodizing treatment, and then a sealing agent mainly composed of nickel acetate. By carrying out the sealing treatment, an anodic oxide coating (alumite coating) of about 6 μm was formed.

Further, 300 parts of 1,2-dimethoxyethane was added to 15 parts of the charge generation substance having the following structure as a charge generation substance, and the mixture was pulverized for 8 hours by a sand grind mill and subjected to atomization dispersion treatment. Subsequently, 7.5 parts of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Denkabutyral” # 6000C) and 7.5 parts of phenoxy resin (product of Union Carbide, PKHH) were added to 1,2-dimethoxyethane 285. 3. Mix with the binder solution dissolved in part, and finally add 135 parts of an arbitrary mixed liquid of 1,2-dimethoxyethane and 4-methoxy-4-methyl-2-pentanone to obtain a solid content (pigment + resin) concentration of 4. A 0 wt% azo pigment dispersion was prepared.

This azo pigment dispersion and the charge generation layer forming dispersion prepared in Example 1 were mixed at a weight ratio of 1: 1 to prepare a charge generation layer forming coating solution containing both the azo pigment and titanyl phthalocyanine. did.
An anodized aluminum cylinder was dip-coated in this charge generation layer forming coating solution, and a charge generation layer was prepared so that the film thickness after drying was 0.6 μm.

  Next, 35 parts each of compound (E) and compound (F) having the following structure as a charge transport material, 70 parts in total, 100 parts of polyester resin Z produced in Production Example 3 as a binder resin, 2 parts of 3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene and silicone oil as a leveling agent (trade name: KF96 Shin-Etsu Chemical Co., Ltd.) ) 0.05 part was mixed with 640 parts of a tetrahydrofuran / toluene (8/2) mixed solvent to prepare a charge transport layer forming coating solution (photosensitive layer forming coating solution) R.

  The charge transport layer forming coating solution is dip-coated on the above-described charge generation layer so that the film thickness after drying is 18 μm, thereby forming a charge transport layer, and a photosensitive drum having a laminated photosensitive layer R1 was obtained.

  Next, in order to examine the stability of the coating solution, the charge transport layer forming coating solution R was stored at room temperature for 3 months. A photoreceptor sheet R3 was produced in the same manner as the photoreceptor sheet R1, except that the charge transport layer forming coating solution N stored at room temperature for 3 months was used. At this time, no symptoms such as gelation were observed in the coating solution R.

[Comparative Example 10]
The 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene used in the coating liquid R for charge transport layer formation in Example 9 is not used. Otherwise, in the same manner as in Example 9, a coating solution S for forming a charge transport layer, a photosensitive drum S1 immediately after preparation of the coating solution, and a photoreceptor S3 after 3 months storage at room temperature of the coating solution were obtained.

[Evaluation]
The electrophotographic photoreceptors R1, R3, S1, and S3 obtained as described above were subjected to the following electrical property test and actual machine evaluation. These results are summarized in Table 2.

<Electrical property test 2>
Attached to an electrophotographic characteristic evaluation apparatus manufactured according to the Electrophotographic Society measurement standard (basic and applied electrophotographic technology, edited by Electrophotographic Society, Corona, page 404-405), and charged and exposed according to the following procedures. The electrical characteristics were evaluated by the cycle of potential measurement and static elimination.

The photosensitive member is charged so that the initial surface potential becomes −700 V, and the halogen lamp light is irradiated with monochromatic light of 405 nm by an interference filter, and the irradiation energy (μJ / cm ² ) was defined as sensitivity E1. The surface potential after exposure (−V) when exposed at 2.0 μJ / cm ² was VL1.
Similarly, the sensitivity E2 and the post-exposure surface potential VL2 were measured in exactly the same procedure using a monochromatic light of 760 nm using an interference filter. Here, all the photoconductors could be measured.
When measuring E1, VL1, E2, and VL2, the time required from the exposure to the potential measurement was 200 ms. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%.

  From this result, it was found that the coating liquid R of Example 9 showed good electrical characteristics under both conditions of 405 nm exposure and 760 nm exposure, either immediately after preparation or after three months of preparation.

<Evaluation of actual machine>
The produced photosensitive drum was mounted on a black drum cartridge of a commercially available tandem type color printer (Microline Pro 9800PS-E manufactured by Oki Data Co., Ltd.) compatible with A3 printing, and mounted on the printer.

Specifications of MICROLINE Pro 9800PS-E · 4 tandem · Color 36ppm, Monochrome 40ppm
・ 1200 dpi
・ DC contact roller charge ・ Writing by LED

  Next, a personal computer was connected to this printer, a grayscale (halftone) image was input, and the density of the output printout was confirmed. A good density image was obtained. When the coating solution S of Comparative Example 10 was used, a decrease in density was observed when printing was repeated using the photoreceptor S3 using the coating solution that had passed three months.

  Also, the exposure part of the same color printer (Microline Pro 9800PS-E manufactured by Oki Data Co., Ltd.) was remodeled so that light from a small spot irradiation type blue LED (B3MP-8: 470 nm) manufactured by Nisshin Electronics could be irradiated to the photoconductor. Remodeled.

  When the photoreceptors R1 and R3 were attached to the remodeling device and lines were drawn, a good image was obtained. Further, when a strobe illumination power source LPS-203KS was connected to the small spot irradiation type blue LED and a point was written, a point image having a radius of 8 mm could be obtained.

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

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. It is an X-ray diffraction diagram showing a powder X-ray diffraction spectrum of oxytitanium phthalocyanine used in Examples and Comparative Examples of the present invention.

Explanation of symbols

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

Claims (11)

A coating solution for forming a photosensitive layer for forming the photosensitive layer of an electrophotographic photosensitive member having a photosensitive layer on a conductive support,
The photosensitive layer forming coating solution contains a polyester resin having a repeating structure represented by the following formula (1), an antioxidant, and a charge transporting substance ,
The coating solution for forming a photosensitive layer, wherein the charge transport material contains at least one of a stilbene derivative and a butadiene derivative .

(In the formula (1), Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X ¹ represents a single bond or a divalent group.) 2. The coating solution for forming a photosensitive layer according to claim 1, wherein the polyester resin contains a repeating structure represented by the following formula (2).

(In formula (2), Ar ^{5 to} Ar ⁸ each independently represents a phenylene group which may have a substituent, and R ¹ represents a hydrogen atom or a methyl group.) 3. The coating solution for forming a photosensitive layer according to claim 1, wherein the antioxidant is a phenolic antioxidant. An electrophotographic photoreceptor comprising a layer formed by coating the photosensitive layer forming coating solution according to claim 1 on a conductive support. An electrophotographic photosensitive member having a photosensitive layer on a conductive support,
The photosensitive layer contains a polyester resin containing a repeating structure represented by the following formula (1), an antioxidant, and a charge transport material ,
The electrophotographic photosensitive member , wherein the charge transport material contains at least one of a stilbene derivative and a butadiene derivative .

(In the formula (1), Ar ^{1 to} Ar ⁴ each independently represents an arylene group which may have a substituent, and X ¹ represents a single bond or a divalent group.) 6. The electrophotographic photosensitive member according to claim 5, wherein the polyester resin includes a repeating structure represented by the following formula (2).

(In formula (2), Ar ^{5 to} Ar ⁸ each independently represents a phenylene group which may have a substituent, and R ¹ represents a hydrogen atom or a methyl group.) 7. The electrophotographic photosensitive member according to claim 5, wherein the antioxidant is a phenolic antioxidant. The electrophotographic photosensitive member according to claim 4, wherein the electrophotographic photosensitive member is used with monochromatic writing light having a wavelength of 380 to 500 nm. The electrophotographic photosensitive member according to any one of claims 4 to 8,
Charging means for charging the electrophotographic photosensitive member, exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, developing means for developing the electrostatic latent image with toner, and the toner An electrophotographic photosensitive member cartridge comprising at least one transfer means for transferring to a transfer target. The electrophotographic photosensitive member according to any one of claims 4 to 8,
Charging means for charging the electrophotographic photosensitive member;
Exposure means for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image with toner;
An image forming apparatus comprising: a transfer unit that transfers the toner to a transfer target. 11. The image forming apparatus according to claim 10, wherein the exposure means performs exposure with monochromatic light having an exposure wavelength of 380 nm to 500 nm.

Images