JP2014157337A - Electrophotographic photoreceptor, electrophotographic cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that contains a binder resin having excellent abrasion resistance to a practical load, excellent electric characteristics while maintaining high mechanical strength, and has high stability of a photosensitive layer formation coating liquid.SOLUTION: An electrophotographic photoreceptor includes a photosensitive layer on a conductive support; and the photosensitive layer contains a polyester resin having a repeating structure of divalent phenol residue and a divalent carboxylic acid residue, and contains a compound represented by the following formula (1) in the divalent phenol residue in an amount of 10 to 60 mole% with respect to the total amount of a divalent phenol component.

Description

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

Electrophotographic technology is used in image forming apparatuses such as copiers and various printers because of its immediacy and high quality images. As a photoreceptor which is the core of electrophotographic technology, a photoreceptor using an organic photoconductive material having advantages such as pollution-free, easy film formation, and easy manufacture is used.
As a photoreceptor using an organic photoconductive material, a so-called single-layer photoreceptor in which a charge generation material is dispersed in a binder resin, and a laminate photoreceptor in which a charge generation layer and a charge transfer layer are laminated are known. ing. In particular, the laminated type photoconductor can provide a highly sensitive photoconductor by combining a highly efficient charge generating material and a charge transfer material, and can provide a highly safe photoconductor with a wide range of material selection. In addition, the photosensitive layer can be easily formed by coating, has high productivity, and is advantageous in terms of cost. Therefore, the photosensitive layer is the mainstream, 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, strongly oxidative ozone generated from a corona charger normally used as a charger, chemical damage caused by NOx to the photosensitive layer, and carrier (current) generated by image exposure. There are chemical and electrical deteriorations such as flowing in, decomposing the photosensitive layer composition due to static elimination light or external light. Furthermore, there is mechanical deterioration such as abrasion of the photosensitive layer surface due to rubbing of a cleaning blade, a magnetic brush or the like, contact with a developer or paper, generation of scratches, peeling of the film, and the like. Such damage due to mechanical deterioration tends to appear on the image, and directly impairs the image quality, which is a major factor that limits the life of the photoreceptor.

In the case of a general photoreceptor not provided with a functional layer such as a surface protective layer, the photosensitive layer is subjected to such a load. The photosensitive layer is usually composed of a binder resin and a photoconductive material, and it is the binder resin that substantially determines the strength, but since the amount of the photoconductive material doped is considerably large, sufficient mechanical strength is provided. Has not reached.
Binder resins that significantly affect the abrasion resistance of the photosensitive layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyester, polysulfone, phenoxy, epoxy, and silicone. Thermoplastic resins such as resins and various thermosetting resins are used. Among the various binder resins, the polycarbonate resin has relatively excellent performance, and various polycarbonate resins have been developed and put into practical use (see Patent Document 1).

  On the other hand, it has been reported that an electrophotographic photoreceptor using a polyester resin marketed under the trade name “U-polymer” as a binder has improved sensitivity as compared with the case of using polycarbonate (see Patent Document 2). ). However, the coating solution prepared by dissolving this resin is low in stability, and coating production may be difficult. To solve this problem, a polyester resin using a divalent phenol component having a specific structure is used as a binder resin, so that the stability of a coating solution used for producing an electrophotographic photosensitive member is improved, and the electrophotographic photosensitive member machine is used. Improvement of mechanical strength and wear resistance has been reported (see Patent Documents 3 to 5). Furthermore, it has been reported that the mechanical strength of the photoreceptor is further improved by using a diphenyl ether dicarboxylic acid component as the dicarboxylic acid component of the polyester resin (see Patent Document 6 and Patent Document 7).

Japanese Patent Laid-Open No. 4-17961 JP-A-56-135844 Japanese Patent Laid-Open No. 3-6567 JP-A-9-22126 JP-A-9-136946 JP 2006-53549 A JP 2008-293006 A

  However, according to the study of the present inventor, the techniques described in Patent Documents 6 and 7 show an improvement in wear resistance, but are not sufficient. On the other hand, as described in Patent Document 1 and Patent Document 5, by including 4,4′-biphenol in polycarbonate or polyester, it is possible to improve the wear resistance, but when the content is increased. Since insoluble components are precipitated during production, the content is limited, and the wear resistance cannot be sufficiently improved.

  The present invention has been made in view of the above problems, and is a binder resin that has excellent wear resistance against practical loads, excellent electrical characteristics while maintaining high mechanical strength, and high stability of a coating solution for forming a photosensitive layer. It is to provide an electrophotographic photoreceptor containing

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

  That is, the invention according to claim 1 is an electrophotographic photosensitive member having a photosensitive layer on a conductive support, wherein the photosensitive layer has a repeating structure of a divalent phenol residue and a divalent carboxylic acid residue. An electrophotographic photoreceptor comprising a polyester resin, wherein the divalent phenol residue contains 10 to 60 mol% of a structural unit represented by the following formula (1) with respect to all divalent phenol components: is there.

(In Formula (1), R < ¹ > -R < ⁸ > is a C1-C20 alkyl group, alkoxyl group, halogen group, or C30 or less which may have a hydrogen atom and a substituent each independently. Represents an aryl group.)
The invention according to claim 2 is characterized in that, in the divalent phenol residue, the divalent phenol other than the structural unit represented by the formula (1) is represented by the following formula (2). This is an electrophotographic photoreceptor.

(In Formula (2), R ^{9 to} R ¹⁶ are each independently a hydrogen atom, an alkyl group that may have a substituent having 1 to 20 carbon atoms, an alkoxyl group, or an aromatic group that may be substituted. X ¹ is any ^one of a single bond, an alkylene group, —CR ¹⁷ R ¹⁸ —, an oxygen atom, and a sulfur atom, and R ¹⁷ and R ¹⁸ are each independently a hydrogen atom or a carbon number of 1 to 20 Or an aryl group optionally having substituent (s), or a group in which R ¹⁷ and R ¹⁸ are bonded to each other to form a ring optionally having substituent (s).
The invention according to claim 3 is the electrophotographic photoreceptor according to claim 1 or 2, wherein the dicarboxylic acid component of the polyester resin is a structural unit represented by the following formula (3). is there.

(In Formula (3), Ar ¹ and Ar ² may be the same or different and each is an arylene group which may have a substituent. X is a single bond, an oxygen atom or a sulfur atom. , A divalent organic residue having the structure represented by formula (4) or the structure represented by formula (5): R ¹⁹ and R ^{20 in} formula (4) are each independently hydrogen An atom, an alkyl group, an aryl group, or a cycloalkylidene group formed by combining R ¹⁹ and R ^20. Further, R ²¹ in the formula (5) represents an alkylene group, an arylene group, or a formula ( 6), wherein R ²² and R ^{23 in} formula (6) each independently represent an alkylene group, Ar ³ represents an arylene group, and k represents an integer of 0 to 5.)

The invention according to claim 4 is the electrophotographic photosensitive member according to any one of claims 1 to 3, wherein a terminal carboxyl value of the polyester resin is 100 mol / ton or less.

The polyester resin containing the dihydric phenol represented by the above formula (1) has high solubility and excellent coating solution stability with respect to the solvent used in the coating solution for forming the photosensitive layer. The photoreceptor is excellent in various properties such as wear resistance and electrical characteristics. The reason for the improvement of the wear resistance and solubility is not clear, but the dihydric phenol such as the above formula (1) is biphenyl having a rigid base skeleton, while hydroxyl at the o, o'-position. It is considered that the resin becomes non-linear by having a group, so that the entire resin structure can have appropriate rigidity (hardness), flexibility, and solubility.

  According to the present invention, an electrophotographic photoreceptor having high stability and excellent electrical characteristics and wear resistance can be obtained.

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

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

In formula (1), R ^{1 to} R ⁸ are each independently a hydrogen atom, an optionally substituted alkyl group, alkoxyl group, halogen group, or aryl group having 30 or less carbon atoms. Represents.
In R ^{1 to} R ⁸ , the optionally substituted alkyl group, alkoxyl group and halogen group having 1 to 20 carbon atoms usually have 20 or less carbon atoms, preferably 6 or less, more preferably 4 or less. It is. The aryl group having 30 or less carbon atoms is preferably 20 or less, more preferably 15 or less. Beyond this range, the wear resistance may be reduced.

  Specific examples of the alkyl group having 1 to 20 carbon atoms which may have this substituent include linear alkyl groups such as methyl group, ethyl group and propyl group, isopropyl group, tertbutyl group and isobutyl group. And a branched alkyl group such as cyclohexyl group and cyclopentyl group, halogenated alkyl groups such as chloromethyl group and methyl fluoride group, and benzyl group. Among these, a linear alkyl group is preferable from the viewpoint of synthesis, and a methyl group or an ethyl group is more preferable.

Specific examples of the alkoxy group having 1 to 20 carbon atoms that may have a substituent in R ^{1 to} R ⁸ include a methoxy group, an ethoxy group, a propoxy group, and a cyclohexoxy group. From the viewpoint of synthesis, a methoxy group or an ethoxy group is preferable.
Specific examples of the aryl group which may have a substituent in R ^{1 to} R ⁸ include a phenyl group, a naphthyl group, an anthranyl group, a pyrenyl group, a chlorophenyl group, and a fluorophenyl group. From the viewpoint of synthesis, a phenyl group or a naphthyl group is preferable.

Specific examples of the halogen group that may have a substituent in R ^{1 to} R ⁸ include a bromo group, a chloro group, and a fluoro group. A bromo group and a chloro group are preferable from the viewpoint of easy availability.
As a preferable combination in R ^{1 to} R ⁸ , R ² , R ⁴ , R ⁵ , and R ⁷ are hydrogen atoms, and R ¹ , R ³ , R ⁶ , and R ⁸ are hydrogen atoms or having 1 to 4 carbon atoms. An alkyl group, an alkoxy group, and a halogen group; Among these, an alkyl group is more preferable from the viewpoint of electrical characteristics.

  Specific examples of the formula (1) include 2,2′-biphenol, 5,5′-dimethyl-2,2′-dihydroxybiphenyl, 5,5′-di-tert-butyl-2,2′-dihydroxybiphenyl, 3,3 ', 5,5'-tetramethyl-2,2'-dihydroxybiphenyl, 6,6'-dimethyl-2,2'-dihydroxybiphenyl, 3,3', 5,5'-tetra-tert-butyl-2,2 '-Dihydroxybiphenyl, 5,5', 6,6'-tetramethyl-3,3'-di-tert-butyl-2,2'-dihydroxybiphenyl, 3,3'-dimethoxy-5,5'-dimethyl-2,2 '-Dihydroxybiphenyl, 5,5'-dimethoxy-3,3'-di-tert-butyl-2,2'-dihydroxybiphenyl, 5,5'-dichloro-2,2'-hydroxybiphe Le, 5,5'-dibromo-2,2'-hydroxybiphenyl and the like. Among these, 2,2′-biphenol is particularly preferable in view of manufacturing convenience. These dihydric phenol components can be used in combination.

In the polyester resin in the present invention, the lower limit of the content of the formula (1) with respect to the total dihydric phenol component is 10 mol% or more, preferably 15 mol% or more. The upper limit is 60 mol% or less, preferably 50 mol% or less. If the content is too small, the wear resistance may be insufficient, and if the content is too large, the solubility may decrease.
In the polyester resin of the present invention, in the divalent phenol residue, the divalent phenol other than the structural unit represented by the above formula (1) is a structural unit represented by the following formula (2). preferable.

In formula (2), R ^{9 to} R ¹⁶ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a halogen group, or a carbon number of 30 or less, optionally having 1 to 20 carbon atoms. X ¹ represents a single bond, an alkylene group, —CR ¹⁷ R ¹⁸ —, an oxygen atom, or a sulfur atom. R ¹⁷ and R ¹⁸ are each independently a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, or a combination of R ¹⁷ and R ¹⁸ bonded together. It represents any of the groups that form a ring that may have a group.

Examples of R ^{9 to} R ¹⁶ include those described in the above R ^{1 to} R ⁸ .
As a preferable combination in R ^{9 to} R ¹⁶ , R ¹⁰ , R ¹² , R ¹³ , and R ¹⁵ are hydrogen atoms, and R ⁹ , R ¹¹ , R ¹⁴ , and R ¹⁶ are hydrogen atoms or having 1 to 3 carbon atoms. It is an alkyl group. From the viewpoint of mechanical properties, R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁵ , and R ¹⁶ are particularly preferably hydrogen atoms, and R ⁹ and R ¹⁴ are each a hydrogen atom or a methyl group.

Specific examples of the alkylene group for X ¹ include — (CH ₂ ) ₂ —, — (CH ₂ ) ₃ — and the like.
Specific examples of the alkyl group that may have a substituent in R ¹⁷ and R ¹⁸ include a methyl group, an ethyl group, a propyl group, and a cyclohexyl group.
Specific examples of the aryl group that may have a substituent in R ¹⁷ and R ¹⁸ include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a tolyl group.

Specific examples of the group in R ¹⁷ and R ¹⁸ in which R ¹⁷ and R ¹⁸ are bonded to each other to form a ring that may have a substituent include a cyclohexylidene group.
In Formula (2), X ¹ is preferably —CR ¹⁷ R ¹⁸ —. Specifically, bis- (4-hydroxyphenyl) methane, 1,1-bis- (4-hydroxyphenyl) ethane, 2,2-bis- (4-hydroxyphenyl) propane, 2,2-bis- ( 4-hydrokey 3-methylphenyl) propane, bis- (4-hydroxy-3-methylphenyl) methane, 1,1-bis- (4-hydroxyphenyl) cyclohexane, 1,1-bis- (4-hydroxy-3) -Methylphenyl) ethane, bis- (4-hydroxy-3,5-dimethylphenyl) methane, 1,1-bis- (4-hydroxy-3,5-dimethylphenyl) ethane, 2,2-bis- (4 -Hydroxy-3,5-dimethylphenyl) propane, bis- (4-hydroxy-3,6-dimethylphenyl) methane, 1,1-bis- (4-hydroxyphenyl) -1-phenyl ethane, 1,1-bis - (4-hydroxyphenyl) propane.

  Among these, bis (4-hydroxyphenyl) methane, 1,1-bis- (4-hydroxyphenyl) ethane, 1,1-bis-(( 4-hydroxy-3-methylphenyl) ethane, bis- (4-hydroxy-3-methylphenyl) methane, 2,2-bis- (4-hydroxy-3-methylphenyl) propane are particularly preferred. It is also possible to use a combination of a plurality of these dihydric phenol components.

  The dicarboxylic acid component of the polyester in the present invention is preferably a structural unit represented by the following formula (3).

In the formula (3), Ar ¹ and Ar ² may be the same or different, and are each independently an arylene group which may have a substituent. X is a divalent organic residue having a single bond, an oxygen atom, a sulfur atom, a structure represented by the formula (4), or a structure represented by the formula (5). R ¹⁹ and R ^{20 in} formula (4) are each independently a hydrogen atom, an alkyl group, or an aryl group, or a cycloalkylidene group formed by combining R ¹⁹ and R ²⁰ . Furthermore, R ²¹ in formula (5) is an alkylene group, an arylene group, or a group represented by formula (6), and R ²² and R ^{23 in} formula (6) are each independently an alkylene group. Ar ³ represents an arylene group. k represents an integer of 0 to 5.

In formula (3), Ar ¹ and Ar ² are not particularly limited, but an arylene group having 6 to 20 carbon atoms is preferable, and examples thereof include a phenylene group, a naphthylene group, an anthrylene group, a phenanthrylene group, and a pyrenylene group. Among these, a phenylene group and a naphthylene group are particularly preferable from the viewpoint of production cost. The substituent that may be independently present in the arylene group is not particularly limited, and preferred examples include a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, a condensed polycyclic group, and a halogen group. Considering the mechanical properties as the 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 or a naphthyl group, and the halogen group is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. The alkoxy group is preferably a methoxy group, an ethoxy group, or a butoxy group. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and 1 to 2 carbon atoms. Are particularly preferable, and specifically, a methyl group is most preferable. The number of substituents for each of Ar ^{1 to} Ar ⁴ is not particularly limited, but is preferably 3 or less, more preferably 2 or less, and particularly preferably 1 or less.
Further, in the formula (3), Ar ¹ and Ar ² are preferably the same arylene group having the same substituent, and particularly preferably an unsubstituted phenylene group.

In Formula (3), X represents a divalent organic residue having a single bond, an oxygen atom, a sulfur atom, a structure represented by Formula (4), or a structure represented by Formula (5). R ¹⁹ and R ^{20 in} formula (4) each independently represent a hydrogen atom, an alkyl group, or an aryl group, or a cycloalkylidene group formed by combining R ¹⁹ and R ²⁰ . Examples of the alkyl group of R ¹⁹ and R ^{20 in} formula (4) include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. Examples of the cycloalkylidene group formed by combining R ¹⁹ and R ²⁰ in formula (4) include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptylidene group. Furthermore, R ²¹ in formula (5) is an alkylene group, an arylene group, or a group represented by formula (6), and R ²² and R ^{23 in} formula (6) are each independently an alkylene group. Ar ³ represents an arylene group. Examples of the alkylene group represented by R ²¹ in formula (5) include a methylene group, an ethylene group, and a propylene group. Examples of the arylene group represented by R ²¹ in formula (5) include a phenylene group and a terphenylene group. It is done. Specific examples of the group represented by the formula (6) include a group represented by the following formula (7). Among these, X is preferably an oxygen atom from the viewpoint of wear resistance.

In formula (3), k is an integer of 0 to 5, preferably 0 to 1, and most preferably 1 from the viewpoint of wear resistance.
In the present invention, the formula (3) is particularly preferably the following general formula (8).

In formula (8), R ²⁴ and R ²⁵ are each independently a hydrogen atom, an alkyl group, an aryl group, a halogen group, or an alkoxy group, and n ¹ and m ¹ are each independently an integer of 0 to 4. is there. R ²⁴ and R ^{25 in} formula (8) are, for example, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms; an aryl group such as a phenyl group or a naphthyl group; a fluorine atom, a chlorine atom, a bromine atom, iodine Halogen groups such as atoms; alkoxy groups such as methoxy, ethoxy and butoxy groups. In consideration of the convenience in the production of the divalent carboxylic acid compound derived from the divalent carboxylic acid residue represented by the formula (8), R ²⁴ and R ²⁵ are a hydrogen atom, an alkyl group having 1 carbon atom (methyl Group) is particularly preferred.

n1 and m1 are each independently an integer of 0 to 4, particularly preferably n1 = m1 = 0.
Specific examples of the divalent carboxylic acid compound derived from the divalent carboxylic acid residue represented by the formula (8) include, for example, diphenyl ether-2,2′-dicarboxylic acid, diphenyl ether-2,4′-dicarboxylic acid, and diphenyl ether. -4,4'-dicarboxylic acid and the like. Among these, diphenyl ether-4,4′-dicarboxylic acid is particularly preferable in view of manufacturing convenience.

  The compound illustrated as Formula (3) can also be used in combination of a some compound as needed. Specific examples of the divalent carboxylic acid compound that can be combined include, for example, adipic acid, suberic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, toluene-2,5-dicarboxylic acid, p-xylene-2,5. -Dicarboxylic acid, pyridine-2,3-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, pyridine-2,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-3,4-dicarboxylic acid, pyridine -3,5-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-2,3-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-4,4 '-Dicarboxylic acid, diphenyl ether-2,2'-dicarboxylic acid, diphenyl ether-2,3'-dicarboxylic acid, diphenyl Ether 2,4'-dicarboxylic acid, diphenyl ether-3,3'-dicarboxylic acid, diphenyl ether-3,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid. Considering the simplicity of production of the dicarboxylic acid component, isophthalic acid, terephthalic acid, and diphenyl ether-4,4′-dicarboxylic acid are particularly preferable.

In addition, it is preferable that the carboxylic acid value of the polyester resin in this invention shall be 100 microequivalent / g or less, More preferably, it is 50 microequivalent / g or less. When the carboxylic acid value exceeds 100 µequivalent / g, the electrical characteristics of the photoreceptor tend to deteriorate, and further, the storage stability when the resin is dissolved in a solvent to form a coating solution tends to be lowered. .
The amount of the free divalent carboxylic acid contained in the polyester resin in the present invention is not particularly limited, but is preferably 50 ppm or less, and more preferably 10 ppm or less. When the content of the free divalent carboxylic acid exceeds 50 ppm, the electrical characteristics of the photoreceptor may be deteriorated or it may become a foreign substance appearing in image evaluation. The smaller the amount of free divalent carboxylic acid, the better from the viewpoint of the electrical properties and image characteristics of the photoreceptor, but from the viewpoint of the stability of the polyester resin, it is preferably 0.01 ppm or more, and 0.1 ppm or more. It is particularly preferred that

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

The polyester resin in the present invention usually contains 10 parts by mass or more, preferably 50 parts by mass or more, more preferably 100 parts by mass with respect to 100 parts by mass of all binder resins in the same layer from the viewpoint of wear resistance. .
For the photosensitive layer in the electrophotographic photoreceptor to which the exemplary embodiment is applied, it is also possible to mix and use a polyester resin having a repeating structure represented by the above-described formula (1) and another resin. Examples of the resin having another structure mixed here include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride or copolymers thereof; polycarbonate resin, polyester resin, polyester polycarbonate resin, polysulfone resin, phenoxy Examples thereof include thermoplastic resins such as resins, epoxy resins, and silicone resins, and various thermosetting resins. Of these resins, polycarbonate resins and polyester resins are preferred. In addition, the mixing ratio of the resin having another structure to be mixed is not particularly limited, but it is usually preferable to use it in a range not exceeding the ratio of the polyester resin having a repeating structure represented by the formula (1). Specifically, the content of the resin having another structure relative to the polyester resin having the repeating structure represented by the formula (1) is usually preferably 50 parts by mass or less and 80 parts by mass or less.

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

  The viscosity average molecular weight (Mv) of the polyester resin having a repeating structure represented by the formula (1) is usually 10,000 to 300,000, preferably 20,000 to 200,000, particularly preferably 25, The range is from 000 to 150,000. When the viscosity average molecular weight (Mv) is excessively small, the mechanical strength when obtained as a film for forming a photoconductor tends to decrease. Moreover, when a viscosity average molecular weight (Mv) is too large, the viscosity as a coating liquid rises and it tends to become difficult to apply | coat to a suitable film thickness.

≪2. Production method of polyester resin >>
Next, the manufacturing method of the polyester resin which has a repeating structure represented by Formula (1) used for the electrophotographic photosensitive member to which this Embodiment is applied is demonstrated. As a method for producing the polyester resin, for example, a known polymerization method such as an interfacial polymerization method, a melt polymerization method, or a solution polymerization method can be used. Here, an example of the manufacturing method of a polyester resin is demonstrated.

In the case of production by the interfacial polymerization method, for example, a solution in which a dihydric phenol compound is dissolved in an alkaline aqueous solution and a halogenated hydrocarbon solution in which an aromatic dicarboxylic acid chloride compound is dissolved are mixed. In this case, a quaternary ammonium salt or a quaternary phosphonium salt can be present as a catalyst. The polymerization temperature is preferably in the range of 0 ° C. to 40 ° C., and the polymerization time is preferably in the range of 2 hours to 20 hours from the viewpoint of productivity. After completion of the polymerization, the aqueous phase and the organic phase are separated,
By washing and collecting the polymer dissolved in the organic phase by a known method, a target 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 component, the range of 1.01 times equivalent-3 times equivalent of the phenolic hydroxyl group contained in a reaction system is preferable.
Examples of the halogenated hydrocarbon include dichloromethane, chloroform, 1,2-dichloroethane, trichloroethane, tetrachloroethane, dichlorobenzene, and the like.

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

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

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

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

  The polyester resin after purification is deposited in water, alcohol or other organic solvent in which the polyester resin is insoluble, or the solvent of the polyester resin is distilled off in warm water or in a dispersion medium in which the polyester resin is insoluble, or heating and decompression For example, the solvent may be removed by distilling off the solvent, and when the slurry is taken out, the solid can be taken out by a centrifuge or a filter.

The obtained polyester resin is usually dried at a temperature equal to or lower than the decomposition temperature of the polyester resin, but can be preferably dried at a temperature not lower than 20 ° C. and not higher than the melting temperature of the resin. At this time, it is preferable to dry under reduced pressure.
Preferably, the drying time is longer than the time until the purity of impurities such as the residual solvent becomes below a certain level. Specifically, the residual solvent is usually 1000 ppm or lower, preferably 300 ppm or lower, more preferably 100 ppm or lower. dry.

≪3. Electrophotographic photoreceptor >>
The electrophotographic photosensitive member to which this exemplary embodiment is applied has a photosensitive layer provided on a conductive support, and the photosensitive layer contains a polyester resin having a repeating structure represented by the above formula (1). To do. As a specific configuration of the photosensitive layer, for example, a laminate in which a charge generation layer mainly composed of a charge generation material and a charge transport layer mainly composed of a charge transport material and a binder resin are stacked on a conductive support. Type photoreceptor; a dispersion type (single layer type) photoreceptor having a photosensitive layer in which a charge generating substance is dispersed in a layer containing a charge transport substance and a binder resin on a conductive support. The polyester resin having a repeating structure represented by the above formula (1) is usually used for a layer containing a charge transport material, and preferably used for a charge transport layer of a multilayer photoreceptor.

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

<3-1. Conductive support>
There is no particular limitation on the conductive support, but for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powder such as metal, carbon, and tin oxide are added to impart conductivity. A resin material, a resin, glass, paper, or the like on which a conductive material such as aluminum, nickel, or ITO (indium tin oxide) is deposited or applied on the surface is mainly used. These may be used alone or in combination of two or more in any combination and ratio. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Further, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

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

<3-2. Undercoat layer>
An undercoat layer may be provided between the conductive support and the photosensitive layer described later for improving adhesion and blocking properties. As the undercoat layer, a resin or a resin in which particles such as a metal oxide are dispersed is used. The undercoat layer may be a single layer or a plurality of layers.

Examples of metal oxide particles used for the undercoat layer include metal oxide particles containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, titanium Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. One kind of these particles may be used alone, or a plurality of kinds of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite, and amorphous can be used. Moreover, the thing of a several crystal state may be contained.
In addition, various particle sizes of metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is preferably 10 nm or more and 100 nm or less, and particularly 10 nm or more and 50 nm or less. preferable. This average primary particle size can be obtained from a TEM photograph or the like.

  The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. The binder resin used for the undercoat layer is epoxy resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, chloride resin. Cellulose esters such as vinylidene resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, polyurethane resin, polyacryl resin, polyacrylamide resin, polyvinyl pyrrolidone resin, polyvinyl pyridine resin, water-soluble polyester resin, nitrocellulose Resin, cellulose ether resin, casein, gelatin, polyglutamic acid, starch, starch acetate, amino starch, zirconium chelate compound, zirconium The organic zirconium compound alkoxide compounds, titanyl chelate compounds, organic titanyl compounds such as titanium alkoxide compounds include known binder resins such as a silane coupling agent. These may be used alone or in combination of two or more in any combination and ratio. Moreover, you may use with the hardening | curing form with the hardening | curing agent. Among these, alcohol-soluble copolymerized polyamides, modified polyamides, and the like are preferable because they exhibit good dispersibility and coatability.

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

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

<3-3-1. Multilayer photosensitive layer>
-Charge generation layer In the case of a multilayer type photoreceptor (function-separated type photoreceptor), the charge generation layer is formed by binding a charge generation substance with a binder resin.

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

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

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

Among these phthalocyanines, A-type (also known as β-type), B-type (also known as α-type), and powder X-ray diffraction angle 2θ (± 0.2 °) are 27.1 ° or 27.3 °. Having strongest peaks at D-type (Y-type) titanyl phthalocyanine, II-type chlorogallium phthalocyanine, V-type, and 28.1 °, and 26.2 °
Hydroxygallium phthalocyanine characterized by having a peak at 28.1 ° without a peak at 0 ° and a full width at half maximum W of 25.9 ° of 0.1 ° ≦ W ≦ 0.4 °, Particularly preferred are G-type μ-oxo-gallium phthalocyanine dimer and the like. Among these, D-type (Y-type) titanyl phthalocyanine is most preferable because it shows good sensitivity.

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

When an azo pigment is used as the charge generation material, various bisazo pigments and trisazo pigments are preferably used.
When an organic pigment is used as the charge generation material, one kind may be used alone, or two or more kinds of pigments may be mixed and used. In this case, it is preferable to use a combination of two or more kinds of charge generating materials having spectral sensitivity characteristics in different spectral regions of the visible region and the near red region. Among them, a disazo pigment, a trisazo pigment and a phthalocyanine pigment are preferably used in combination. More preferred.

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

Specifically, the charge generation layer is prepared by dispersing the halogen-substituted indium phthalocyanine of the present invention and other charge generation materials used in some cases in a solution obtained by dissolving the above-described binder resin in an organic solvent. Is applied on a conductive support (or an undercoat layer when an undercoat layer is provided).
The solvent used for preparing the coating solution is not particularly limited as long as it dissolves the binder resin. For example, saturated aliphatic solvents such as pentane, hexane, octane, and nonane, and aromatics such as toluene, xylene, and anisole. Group solvents, halogenated aromatic solvents such as chlorobenzene, dichlorobenzene, chloronaphthalene, amide solvents such as dimethylformamide, N-methyl-2-pyrrolidone, methanol, ethanol, isopropanol, n-butanol, benzyl alcohol, etc. Alcohol solvents, aliphatic polyhydric alcohols such as glycerin and polyethylene glycol, chain or cyclic ketone solvents such as acetone, cyclohexanone, methyl ethyl ketone, ester solvents such as methyl formate, ethyl acetate, n-butyl acetate, methylene chloride ,Black Halogenated hydrocarbon solvents such as form, 1,2-dichloroethane, chain or cyclic ether solvents such as diethyl ether, dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, acetonitrile, dimethyl Aprotic polar solvents such as sulfoxide, sulfolane, hexamethylphosphoric triamide, n-butylamine, isopropanolamine, diethylamine, triethanolamine, nitrogen-containing compounds such as ethylenediamine, triethylenediamine, triethylamine, mineral oil such as ligroin, water, etc. Can be mentioned. Any one of these may be used alone, or two or more of these may be used in combination. In addition, when providing the above-mentioned undercoat layer, what does not melt | dissolve this undercoat layer is preferable.

  In the charge generation layer, the mixing ratio (mass) of the binder resin and the charge generation material is usually 10 parts by mass or more, preferably 30 parts by mass or more, and usually 1000 parts by mass with respect to 100 parts by mass of the binder resin. Part or less, preferably 500 parts by mass or less, and the film thickness is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material, while if the ratio of the charge generation material is too low, the sensitivity as a photoreceptor may be decreased. There is.

  As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, or a sand mill dispersion method can be used. At this time, it is effective to refine the particles to a particle size in the range of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

-Charge transport layer The charge transport layer of the multilayer photoconductor contains a charge transport material and usually contains a binder resin and other components used as necessary. Specifically, such a charge transport layer is prepared by, for example, preparing a coating solution by dissolving or dispersing a charge transport material and a binder resin in a solvent. In addition, in the case of a reverse lamination type photosensitive layer, it can be obtained by coating and drying on a conductive support (or on the undercoat layer when an undercoat layer is provided).

  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. Specific examples of suitable structures of the charge transport material are shown below. Specific examples are shown below 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.

  Specific examples of the charge transport material contained in the charge transport layer constituting the photosensitive layer of the electrophotographic photoreceptor to which the exemplary embodiment is applied include, for example, arylamine-based compounds described in JP-A-9-244278. Compounds, arylamine compounds described in JP-A No. 2002-275133, enamine compounds described in JP-A 2009-20504, and the like. These charge transport materials may be used alone or in combination. The charge transport layer is formed in such a form that these charge transport materials are bound to the binder resin. The charge transport layer may be composed of a single layer, or may be a stack of a plurality of layers having different constituent components or composition ratios.

The polyester resin having a repeating structure represented by the above formula (1) is preferably used as a binder resin for the charge transport layer. The binder resin may be a mixture of the polyester resin used in the present invention and a resin having another structure. Examples of the other resin include those described in Resins having other structures mixed in the photosensitive layer. Can be mentioned.
The ratio of the binder resin composed of the polyester resin having a repeating structure represented by the formula (1) and the charge transport material is usually 30 parts by mass to 200 parts by mass with respect to 100 parts by mass of the binder resin, preferably , 40 parts by mass to 150 parts by mass. The ratio of the entire binder resin and the charge transport material in the photosensitive layer is preferably 20 parts by mass or more with respect to 100 parts by mass of the binder resin. Especially, 30 mass parts or more are more preferable from a viewpoint of residual potential reduction, and 40 mass parts or more are still more preferable from a viewpoint of stability and charge mobility at the time of using repeatedly. On the other hand, from the viewpoint of thermal stability of the photosensitive layer, it is preferable to use the charge transport material in a ratio of usually 150 parts by mass or less. Especially, 110 mass parts or less are more preferable from a compatible viewpoint of charge transport material and binder resin. The film thickness of the charge transport layer is usually 5 μm to 50 μm, preferably 10 μm to 45 μm.

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

<3-3-2. Single-layer type photosensitive layer>
The single-layer type photosensitive layer is formed using a binder resin in order to ensure film strength, in the same manner as the charge transport layer of the multilayer photoconductor, in addition to the charge generation material and the charge transport material. Specifically, a charge generation material, a charge transport material, and various binder resins are dissolved or dispersed in a solvent to prepare a coating solution, and on a conductive support (or an undercoat layer when an undercoat layer is provided). It can be obtained by coating and drying.

The types of the charge transport material and the binder resin and the use ratios thereof are the same as those described for the charge transport layer of the multilayer photoreceptor. The charge generating material is further dispersed in the charge transport medium comprising these charge transport material and binder resin.
As the charge generation material, the same materials as those described for the charge generation layer of the multilayer photoreceptor can be used. However, in the case of a photosensitive layer of a single-layer type photoreceptor, it is necessary to sufficiently reduce the particle size of the charge generating material. Specifically, the range is usually 1 μm or less, preferably 0.5 μm or less.

If the amount of the charge generating material dispersed in the single-layer type photosensitive layer is too small, sufficient sensitivity cannot be obtained, but if it is too large, there are adverse effects such as a decrease in chargeability and a decrease in sensitivity. It is used in the range of usually 0.5% by mass or more, preferably 1% by mass or more, and usually 50% by mass or less, preferably 20% by mass or less based on the whole layer-type photosensitive layer.
In addition, the usage ratio of the binder resin and the charge generation material in the single-layer type photosensitive layer is such that the charge generation material is usually 0.1 parts by weight or more, preferably 1 part by weight or more, based on 100 parts by weight of the binder resin. It is 30 mass parts or less, Preferably it is set as the range of 10 mass parts or less.

  The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less. Also in this case, known plasticizers for improving film formability, flexibility, mechanical strength, additives for suppressing residual potential, dispersion aids for improving dispersion stability, coatability Leveling agents and surfactants such as silicone oil, fluorine oil and other additives may be added to improve the viscosity.

<3-4. Other functional layers>
For the purpose of improving film forming properties, flexibility, coating properties, contamination resistance, gas resistance, light resistance, etc., in both the photosensitive layer and the layers constituting the photosensitive layer, both of the multilayer type photosensitive member and the single layer type photosensitive member. Additives such as well-known antioxidants, plasticizers, ultraviolet absorbers, electron-withdrawing compounds, leveling agents, and visible light shielding agents may be included.

Further, for the purpose of reducing the frictional resistance and wear on the surface of the photoconductor, and increasing the transfer efficiency of the toner from the photoconductor to the transfer belt and paper, etc., the surface layer is made of fluorine resin, silicon resin, polyethylene resin, or the like. Particles made of this resin or inorganic compound particles may be contained in the surface layer. Alternatively, a layer containing these resins and particles may be newly formed as a surface layer.
Furthermore, it goes without saying that a layer for improving electrical properties and mechanical properties, such as an intermediate layer such as a barrier layer, an adhesive layer and a blocking layer, and a transparent insulating layer, may be provided as necessary.

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

  There are no particular restrictions on the solvent or dispersion medium used in the preparation of the coating solution, but specific examples include alcohols such as methanol, ethanol, propanol and 2-methoxyethanol, tetrahydrofuran, 1,4-dioxane, dimethoxyethane and the like. Ethers, esters such as methyl formate and ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene and xylene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1, Chlorinated hydrocarbons such as 2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, 1,2-dichloropropane, trichloroethylene, n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine , Nitrogen-containing compounds such as triethylenediamine, acetonitrile, N- methylpyrrolidone, N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

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

In the case of a charge generation layer of a multilayer photoreceptor, the solid content concentration of the coating solution is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass. % Or less. The viscosity of the coating solution is usually 0.01 cps or more, preferably 0.1 cps or more, and usually 20 cps or less, preferably 10 cps or less.
Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used.
The coating solution is preferably dried by touching at room temperature, followed by heating or drying in a temperature range of usually 30 ° C. or more and 200 ° C. or less for 1 minute to 2 hours, while still or blowing. The heating temperature may be constant or the heating may be performed while changing the temperature during drying.

<4. Image forming apparatus>
Next, an embodiment of an image forming apparatus using the electrophotographic photoreceptor of the present invention (an image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

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

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

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

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

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

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

The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like that are disposed to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

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

  The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. 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 electrophotographic photosensitive member 1 is combined with one or more of the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge ( The electrophotographic photosensitive member cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, for example, when the electrophotographic photosensitive member 1 and other members are deteriorated, the electrophotographic photosensitive member cartridge is removed from the main body of the image forming apparatus, and another new electrophotographic photosensitive member cartridge is mounted on the main body of the image forming apparatus. This facilitates maintenance and management of the image forming apparatus.

Specific embodiments of the present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.
[Production of polyester resin]
Production Example 1 (Method for producing polyester resin (1))
Sodium hydroxide (4.27 g) and H ₂ O (188 ml) were weighed in a 300 mL beaker and dissolved with stirring. There, hydrosulfite sodium (0.57 g), 2,3,5-trimethylphenol (0.27 g), 2,2′-biphenol (2.43 g) (hereinafter referred to as BP-a), 1,1-bis (4-Hydroxy-3, methylphenyl) ethane (7.36 g) (hereinafter referred to as BP-b) and benzyltriethylammonium chloride (0.12 g) were added in this order and dissolved with stirring, and then this alkaline aqueous solution was added to a 1 L reactor. Moved.

Separately, a mixed solution of diphenyl ether-4,4′-dicarboxylic acid chloride (13.16 g) and dichloromethane (94 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (157 mL) was added and stirring was continued for 7 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed with 0.1 N hydrochloric acid (190 mL) three times, and further washed with demineralized water (190 mL) twice.

  The washed organic layer was diluted with 250 ml of methylene chloride, poured into methanol (2000 ml), and the resulting precipitate was filtered out and dried to obtain the desired polyester resin (1). The viscosity average molecular weight of the obtained polyester resin (1) was 31,900. The structural formula of the obtained polyester resin (1) is shown below.

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

Production Example 2 (Production Method of Polyester Resin (2))
Sodium hydroxide (10.81 g) and H ₂ O (470 ml) were weighed in a 1 L beaker and dissolved with stirring. There, hydrosulfite sodium (0.73 g), 2,3,5-trimethylphenol (0.39 g), BP-a (8.27 g), BP-b (16.14 g) and benzyltriethylammonium chloride (0 .29 g) in this order, and dissolved by stirring, and then the aqueous alkaline solution was transferred to a 2 L reactor.

Separately, a mixed solution of diphenyl ether-4,4′-dicarboxylic acid chloride (33.35 g) and dichloromethane (235 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (392 mL) was added and stirring was continued for 7 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed with 0.1 N hydrochloric acid (470 mL) three times, and further washed twice with demineralized water (470 mL).

  The washed organic layer was diluted with 620 ml of methylene chloride, poured into methanol (5000 ml), and the resulting precipitate was removed by filtration and dried to obtain the desired polyester resin (2). The viscosity average molecular weight of the obtained polyester resin (2) was 42,000. The structural formula of the obtained polyester resin (2) is shown below.

Production Example 3 (Method for producing polyester resin (3))
Sodium hydroxide (4.38 g) and H ₂ O (188 ml) were weighed in a 300 mL beaker and dissolved with stirring. There, hydrosulfite sodium (0.49 g), 2,3,5-trimethylphenol (0.20 g), BP-a (4.17 g), BP-b (5.43 g) and benzyltriethylammonium chloride (0 .12 g) was added in order and dissolved by stirring, and the aqueous alkaline solution was transferred to a 1 L reaction vessel.

Separately, a mixed solution of diphenyl ether-4,4′-dicarboxylic acid chloride (13.50 g) and dichloromethane (94 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (157 mL) was added and stirring was continued for 7 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed with 0.1 N hydrochloric acid (190 mL) three times, and further washed with demineralized water (190 mL) twice.

  The washed organic layer was diluted with 250 ml of methylene chloride, poured into methanol (2000 ml), and the resulting precipitate was filtered off and dried to obtain the desired polyester resin (3). The viscosity average molecular weight of the obtained polyester resin (3) was 29,600. The structural formula of the obtained polyester resin (3) is shown below.

Production Example 4 (Production Method of Polyester Resin (4))
Sodium hydroxide (4.49 g) and H ₂ O (188 ml) were weighed in a 300 mL beaker and dissolved with stirring. There, hydrosulfite sodium (0.28 g), 2,3,5-trimethylphenol (0.13 g), BP-a (6.04 g), BP-b (3.37 g) and benzyltriethylammonium chloride (0 .12 g) was added in order and dissolved by stirring, and the aqueous alkaline solution was transferred to a 1 L reaction vessel.

Separately, a mixed solution of diphenyl ether-4,4′-dicarboxylic acid chloride (13.86 g) and dichloromethane (94 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (157 mL) was added and stirring was continued for 7 hours. As a result, the product precipitated in the reaction vessel, and no further operation was performed.

Production Example 5 (Method for producing polyester resin (5))
Weigh sodium hydroxide (10.58 g) and H ₂ O (470 ml) in a 1 L beaker,
It was dissolved with stirring. 2,3,5-trimethylphenol (0.59 g), bis (2-hydroxyphenyl) methane (hereinafter BP-c), (2-hydroxyphenyl) (4-hydroxyphenyl) methane (hereinafter BP-) d), a mixture of bis (4-hydroxyphenyl) methane (hereinafter referred to as BP-e) (mixing ratio, BP-c: BP-d: BP-e = 17: 45: 38 (hereinafter referred to as BP-f)) ( 6.48 g), BP-b (18.30 g) and benzyltriethylammonium chloride (0.29 g) were added in this order and dissolved by stirring, and then the aqueous alkaline solution was transferred to a 2 L reaction vessel.

Separately, a mixed solution of diphenyl ether-4,4′-dicarboxylic acid chloride (32.64 g) and dichloromethane (235 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (392 mL) was added and stirring was continued for 10 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed with 0.1 N hydrochloric acid (470 mL) three times, and further washed twice with demineralized water (470 mL).

  The washed organic layer was diluted with 620 ml of methylene chloride, poured into methanol (5000 ml), and the resulting precipitate was removed by filtration and dried to obtain the desired polyester resin (5). The viscosity average molecular weight of the obtained polyester resin (5) was 37,000. The structural formula of the obtained polyester resin (5) is shown below.

Production Example 6 (Method for producing polyester resin (6))
Weigh sodium hydroxide (10.98 g) and H ₂ O (470 ml) in a 1 L beaker,
It was dissolved with stirring. There, hydrosulfite sodium (1.86 g), 2,3,5-trimethylphenol (0.73 g), 4,4′-biphenol (3.98 g) (hereinafter referred to as BP-g), BP-b (20 .73 g) and benzyltriethylammonium chloride (0.28 g) were added in this order and dissolved by stirring, and the aqueous alkaline solution was transferred to a 1 L reaction vessel.

Separately, a mixed solution of diphenyl ether-4,4′-dicarboxylic acid chloride (32.51 g) and dichloromethane (235 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (392 mL) was added and stirring was continued for 7 hours. Thereafter, stirring was stopped and the mixture was allowed to stand for 30 minutes, and then the organic layer was separated. This organic layer was washed with 0.1 N hydrochloric acid (470 mL) three times, and further washed twice with demineralized water (470 mL).

  The washed organic layer was diluted with 620 ml of methylene chloride, poured into methanol (5000 ml), and the resulting precipitate was removed by filtration and dried to obtain the desired polyester resin (6). The viscosity average molecular weight of the obtained polyester resin (6) was 46,200. The structural formula of the obtained polyester resin (6) is shown below.

Production Example 7 (Method for producing polyester resin (7))
Sodium hydroxide (4.27 g) and H ₂ O (188 ml) were weighed in a 300 mL beaker and dissolved with stirring. There, hydrosulfite sodium (0.57 g), 2,3,5-trimethylphenol (0.29 g), BP-g (2.42 g), BP-b (7.35 g) and benzyltriethylammonium chloride (0 .12 g) was added in order and dissolved by stirring, and the aqueous alkaline solution was transferred to a 1 L reaction vessel.

Separately, a mixed solution of diphenyl ether-4,4′-dicarboxylic acid chloride (13.16 g) and dichloromethane (94 mL) was transferred into the dropping funnel.
While maintaining the external temperature of the reaction vessel at 20 ° C. and stirring the alkaline aqueous solution in the reaction vessel, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 1 hour, dichloromethane (157 mL) was added and stirring was continued for 7 hours. As a result, the product precipitated in the reaction vessel, and no further operation was performed.

Production Example 8 (Production Method of Polyester Resin (8))
A polyester resin (8) was produced in the same manner as in Production Example 1 except that sodium hydrosulfite was not used.
Production Example 9 (Production Method of Polyester Resin (9))
A polyester resin (9) (viscosity average molecular weight 36,200) having the following structure was produced by the method described in Example 6 of JP-A-2006-53549.

<Carboxylic acid value measurement>
After weighing 0.20 g of resin in a 50 mL beaker and heating and dissolving with 25 mL of benzyl alcohol, 0.01N NaOH benzyl alcohol solution using an automatic titrator GT-200 manufactured by Mitsubishi Chemical Analytech Co., Ltd. The carboxylic acid value was determined by neutralization titration with The results are shown in Table-1.

  From the results of Table 1, when synthesizing a polyester resin by interfacial polymerization using 2,2′-biphenol, the addition of sodium hydrosulfite can greatly reduce the carboxylic acid value in the resin compared to the case of no addition. It is clear that

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

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

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

This charge transport layer forming coating solution is applied onto the above-described charge generation layer using an applicator so that the film thickness after drying is 25 μm, and dried at 125 ° C. for 20 minutes to form a charge transport layer. A photoreceptor sheet was prepared.
[Example 3]
A photoreceptor sheet was produced in the same manner as in Example 2 except that the polyester resin (1) was changed to the polyester resin (2).

[Example 4]
A photoreceptor sheet was produced in the same manner as in Example 2 except that the polyester resin (1) was changed to the polyester resin (3).
[Comparative Example 2]
Since the polyester resin (4) was precipitated during the polymerization, a photoreceptor sheet could not be prepared.

[Comparative Example 3]
A photoreceptor sheet was produced in the same manner as in Example 2 except that the polyester resin (1) was changed to the polyester resin (5).
[Comparative Example 4]
A photoreceptor sheet was produced in the same manner as in Example 2 except that the polyester resin (1) was changed to the polyester resin (6).

[Comparative Example 5]
Since the polyester resin (7) was precipitated during the polymerization, a photoreceptor sheet could not be prepared.
[Comparative Example 6]
A photoreceptor sheet was produced in the same manner as in Example 2 except that the polyester resin (1) was changed to the polyester resin (9).

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

<Production of photosensitive drum>
[Example 5]
The undercoat layer dispersion was prepared as follows. High-speed fluidized mixing of rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) Disperse the surface-treated titanium oxide obtained by mixing in a kneading machine (“SMG300” manufactured by Kawata Co., Ltd.) and mixing at high speed at a rotational peripheral speed of 34.5 m / sec using a ball mill of methanol / 1-propanol. Thus, a dispersion slurry of hydrophobized titanium oxide was obtained. The dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula ( Compound represented by B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula The compound molar ratio of the compound represented by (E) is 75% / 9.5%
/3%/9.5%/3% of the copolyamide pellets heated and stirred and mixed to dissolve the polyamide pellets, and then subjected to ultrasonic dispersion treatment to obtain methanol / 1-propanol. An undercoating layer dispersion having a solid content concentration of 18.0% and containing a hydrophobic / titanium mass ratio of 7/1/2 and a hydrophobically treated titanium oxide / copolymerized polyamide at a mass ratio of 3/1.

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

  The charge transport layer coating solution was prepared as follows. 75 parts by mass of a charge transport material comprising an isomer mixture mainly composed of the charge transport material (CTM-1), 100 parts by mass of the polyester resin (2) produced in Production Example 1, and an antioxidant (Irganox 1076) ) 4 parts by mass, 0.05 part by mass of silicone oil (trade name KF96, manufactured by Shin-Etsu Chemical Co., Ltd.) is mixed with 640 parts by mass of a tetrahydrofuran / toluene mixed solvent (tetrahydrofuran 80% by mass, toluene 20% by mass) to form a charge transport layer. A coating solution was prepared.

Subsequently, the coating film for forming the undercoat layer obtained as described above was applied to a 3003 series aluminum alloy tube having a diameter of 30 mm, a length of 246 mm, and a wall thickness of 0.75 mm. A subbing layer was provided by dip coating to a thickness of 5 μm and drying at room temperature.
Further, the charge generation layer forming coating solution β obtained as described above is dip-coated on the undercoat layer so that the film thickness after drying is about 0.3 μm, and dried at room temperature. A charge generation layer was provided.
Subsequently, a photosensitive drum D1 was produced in which the charge transport layer forming coating solution was dip-coated on the charge generation layer so that the film thickness after drying was about 20 μm.

[Comparative Example 7]
A photosensitive drum D2 was produced in the same manner as in Example 5 except that the polyester resin (2) was changed to the polyester resin (5).
[Comparative Example 8]
A photosensitive drum D3 was produced in the same manner as in Example 5 except that the polyester resin (2) was changed to the polyester resin (6).

[Comparative Example 9]
It implemented except having changed the polyester resin (2) into the polyester resin (10) (viscosity average molecular weight 40,000) which has the structure shown below manufactured by the method as described in Example 6 of Unexamined-Japanese-Patent No. 2006-53549. In the same manner as in Example 5, a photosensitive drum D4 was produced.

[Measurement of film loss by wear test]
These photoconductors were mounted on a commercially available color printer COREFIDO C711dn (manufactured by Oki Data Co., Ltd.), and 40,000 sheets were printed under normal temperature and humidity. The film reduction amount per sheet was calculated, and the results are shown in Table 3. The smaller the film reduction amount, the better the wear resistance.

From the results in Table 2, it is clear that even when 50 mol% or more of 2,2′-biphenol in all bisphenols is introduced into the polyester resin, the polyester resin has high solubility and good electrical characteristics. On the other hand, when 4,4′-biphenol is contained in the polyester resin, the solubility is lowered, and only less than 30 mol% can be introduced.
From the results in Table 3, the abrasion resistance is improved by incorporating 2,2′-biphenol in the polyester resin. On the other hand, if the polyester resin contains bis (2-hydroxyphenyl) methane having one more methylene chain than 2,2′-biphenol, the wear resistance deteriorates. Further, it is clear that the wear resistance is not improved even when 4,4′-biphenol is contained.

  From the above results, it has been clarified that the use of the polyester resin in the present invention can provide a photoreceptor having high wear resistance as well as good characteristics such as electrical characteristics and coating properties.

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

Claims (4)

An electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the photosensitive layer contains a polyester resin having a repeating structure of a divalent phenol residue and a divalent carboxylic acid residue, and the divalent phenol An electrophotographic photoreceptor, wherein the residue contains a structural unit represented by the following formula (1) in an amount of 10 to 60 mol% based on all dihydric phenol components.

(In Formula (1), R < ¹ > -R < ⁸ > is a C1-C20 alkyl group, alkoxyl group, halogen group, or C30 or less which may have a hydrogen atom and a substituent each independently. Represents an aryl group.) 2. The electrophotographic photoreceptor according to claim 1, wherein in the divalent phenol residue, the divalent phenol other than the structural unit represented by the formula (1) is represented by the following formula (2).

(In formula (2), R ^{9 to} R ¹⁶ are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a halogen group, or a carbon number of 30 or less, which may have a substituent, having 1 to 20 carbon atoms. X ¹ represents a single bond, an alkylene group, —CR ¹⁷ R ¹⁸ —, an oxygen atom, or a sulfur atom, R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom, a carbon number of 1 to 20 represents an alkyl group, an aryl group which may have a substituent, or a group in which R ¹⁷ and R ¹⁸ are bonded to each other to form an optionally substituted ring.) The electrophotographic photosensitive member according to claim 1, wherein the dicarboxylic acid component of the polyester resin is a structural unit represented by the following formula (3).

(In Formula (3), Ar ¹ and Ar ² may be the same or different, and each independently represents an arylene group which may have a substituent. X represents a single bond, an oxygen atom, or a sulfur atom. Represents a divalent organic residue having the structure represented by formula (4) or the structure represented by formula (5), wherein R ¹⁹ and R ^{20 in} formula (4) are each independently hydrogen; It represents an atom, an alkyl group, an aryl group, or a cycloalkylidene group formed by combining R ¹⁹ and R ^20. Furthermore, R ²¹ in formula (5) represents an alkylene group, an arylene group, or a formula ( 6), wherein R ²² and R ^{23 in} formula (6) each independently represent an alkylene group, Ar ³ represents an arylene group, and k represents an integer of 0 to 5.)

The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein a terminal carboxyl value of the polyester resin is 100 µequivalent / g or less.

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