JP2022049733A - Polyarylate resin, and electrophotographic photoreceptor - Google Patents

Abstract

To provide a polyarylate resin which enables abrasion resistance and sensitivity characteristics of a photosensitive layer of a photoreceptor to be improved when the polyarylate resin is contained in the photosensitive layer of the photoreceptor, and enables liquid life characteristics of coating liquid for a photosensitive layer to be improved when the polyarylate resin is contained in the coating liquid for the photosensitive layer, and an electrophotographic photoreceptor including the polyarylate resin.SOLUTION: An electrophotographic photoreceptor is provided, comprising a wholly aromatic polyarylate resin, a conductive base material and a photosensitive layer, wherein the photosensitive layer contains a charge generator, a hole transport agent and a binder resin, and the binder resin includes the polyarylate resin.SELECTED DRAWING: None

Description

The present invention relates to a polyarylate resin and an electrophotographic photosensitive member.

The electrophotographic photosensitive member is used as an image carrier in an electrophotographic image forming apparatus (for example, a printer or a multifunction device). The electrophotographic photosensitive member includes a photosensitive layer. As the electrophotographic photosensitive member, for example, a single-layer electrophotographic photosensitive member and a laminated electrophotographic photosensitive member are used. The single-layer electrophotographic photosensitive member includes a single-layer photosensitive layer having a function of generating charges and a function of transporting charges. The laminated electrophotographic photosensitive member includes a photosensitive layer including a charge generating layer having a charge generating function and a charge transporting layer having a charge transporting function.

Patent Document 1 describes an electrophotographic photosensitive member having a photosensitive layer. The binder resin of this photosensitive layer is a polyarylate resin containing a structure represented by the following chemical formula.

Japanese Patent Application Laid-Open No. 2003-322982

However, according to the studies by the present inventors, it has been found that the electrophotographic photosensitive member described in Patent Document 1 is insufficient in terms of wear resistance, sensitivity characteristics, and liquid life characteristics.

The present invention has been made in view of the above problems, and an object thereof is to improve wear resistance and sensitivity characteristics when contained in the photosensitive layer of an electrophotographic photosensitive member, and to apply the electrophotographic photosensitive member to the photosensitive layer. It is an object of the present invention to provide a polyarylate resin capable of improving liquid life characteristics when contained in a liquid. Another object of the present invention is to provide an electrophotographic photosensitive member having excellent wear resistance, sensitivity characteristics, and liquid life characteristics.

The polyarylate resin of the present invention is represented by the general formula (1).

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a methyl group. X represents a divalent group represented by the general formula (X1) or (X2). Y represents a divalent group represented by the chemical formula (Y1), (Y2), or (Y3). m represents a number of 50 or more and less than 100.

In the general formula (X1), t represents 1 or 2, and * represents a bond. In the general formula (X2), R ³ and R ⁴ represent a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, R ³ and R ⁴ represent groups different from each other, and * represents a bond. show.

In the chemical formulas (Y1), (Y2), and (Y3), * represents a bond.

The electrophotographic photosensitive member of the present invention includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generator, a hole transport agent, and a binder resin. The binder resin contains the polyarylate resin.

The polyarylate resin of the present invention can improve wear resistance and sensitivity characteristics when contained in the photosensitive layer of an electrophotographic photosensitive member, and has liquid life characteristics when contained in a coating liquid for a photosensitive layer of an electrophotographic photosensitive member. Can be improved. The electrophotographic photosensitive member of the present invention is excellent in wear resistance, sensitivity characteristics, and liquid life characteristics.

It is a partial cross-sectional view of the laminated electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on 2nd Embodiment of this invention. It is a partial cross-sectional view of the laminated electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on 2nd Embodiment of this invention. It is a partial cross-sectional view of the laminated electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on 2nd Embodiment of this invention. It is a partial cross-sectional view of the single-layer type electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on 2nd Embodiment of this invention. It is a partial cross-sectional view of the single-layer type electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on 2nd Embodiment of this invention. It is a partial cross-sectional view of the single-layer type electrophotographic photosensitive member which is an example of the electrophotographic photosensitive member which concerns on 2nd Embodiment of this invention. It is ¹ H-NMR spectrum figure of the polyarylate resin (R-3). It is an enlarged view near the range of 1.0ppm or more and 2.5ppm or less of ¹ H-NMR spectrum shown in FIG. 7. It is an enlarged view near the range of 7.0ppm or more and 8.3ppm or less of ¹ H-NMR spectrum shown in FIG. 7.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention. The description may be omitted as appropriate for the parts where the explanations are duplicated, but the gist of the invention is not limited. Hereinafter, the compound and its derivatives may be collectively referred to by adding "system" after the compound name. Further, when the polymer name is represented by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative. Unless otherwise specified, each component described in the present specification may be used alone or in combination of two or more. Unless otherwise specified, the viscosity average molecular weight is a value measured according to JIS (Japanese Industrial Standards) K7252-1: 2016.

First, the substituents used in the present specification will be described. Unless otherwise specified, the alkyl group having 1 or more and 8 or less carbon atoms, the alkyl group having 1 or more and 6 or less carbon atoms, the alkyl group having 1 or more and 3 or less carbon atoms, and the alkyl group having 3 carbon atoms are directly described. It is chain-like or branched chain-like and unsubstituted. Examples of the alkyl group having 1 or more and 8 or less carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, and an n-pentyl group, and 1 -Methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 2-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethyl Butyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethylbutyl Examples include groups, 2-ethylbutyl and 3-ethylbutyl groups, linear and branched heptyl groups, and linear and branched octyl groups. Examples of the alkyl group having 1 or more and 6 or less carbon atoms, the alkyl group having 1 or more and 3 or less carbon atoms, and the alkyl group having 3 carbon atoms are described as examples of the alkyl group having 1 or more and 8 or less carbon atoms, respectively. Among the groups, it is a group having a corresponding number of carbon atoms.

Unless otherwise specified, the alkoxy group having 1 or more and 8 or less carbon atoms and the alkoxy group having 1 or more and 3 or less carbon atoms are linear or branched and unsubstituted. Examples of the alkoxy group having 1 or more and 8 or less carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group and an n-pentoxy group. 1-methylbutoxy group, 2-methylbutoxy group, 3-methylbutoxy group, 1-ethylpropoxy group, 2-ethylpropoxy group, 1,1-dimethylpropoxy group, 1,2-dimethylpropoxy group, 2,2- Dimethylpropoxy group, n-hexyloxy group, 1-methylpentyloxy group, 2-methylpentyloxy group, 3-methylpentyloxy group, 4-methylpentyloxy group, 1,1-dimethylbutoxy group, 1,2- Dimethylbutoxy group, 1,3-dimethylbutoxy group, 2,2-dimethylbutoxy group, 2,3-dimethylbutoxy group, 3,3-dimethylbutoxy group, 1,1,2-trimethylpropoxy group, 1,2, 2-trimethylpropoxy group, 1-ethylbutoxy group, 2-ethylbutoxy group, 3-ethylbutoxy group, linear and branched heptyloxy group, and linear and branched octyloxy group. Can be mentioned. An example of an alkoxy group having 1 or more and 3 or less carbon atoms is a group having a corresponding carbon atom number among the groups described as an example of an alkoxy group having 1 or more and 8 or less carbon atoms. The substituents used in the present specification have been described above.

<First Embodiment: Polyarylate resin>
The first embodiment of the present invention relates to a polyarylate resin. The polyarylate resin of the first embodiment is represented by the general formula (1). Hereinafter, the polyarylate resin represented by the general formula (1) may be referred to as a polyarylate resin (1).

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a methyl group. X represents a divalent group represented by the general formula (X1) or (X2). Y represents a divalent group represented by the chemical formula (Y1), (Y2), or (Y3). m represents a number of 50 or more and less than 100.

In the general formula (X1), t represents 1 or 2, and * represents a bond. In the general formula (X2), R ³ and R ⁴ represent a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, R ³ and R ⁴ represent groups different from each other, and * represents a bond. ..

In the chemical formulas (Y1), (Y2), and (Y3), * represents a bond.

The divalent group represented by the chemical formula (Y1), (Y2), or (Y3) of the polyarylate resin (1) has an —OCO— group. The divalent group represented by the chemical formula (Y1), (Y2), or (Y3) having the -OCO- group does not make the polyarylate resin (1) too rigid, and imparts appropriate elasticity. As a result, when the polyarylate resin (1) is contained in the photosensitive layer of the electrophotographic photosensitive member (hereinafter referred to as the photosensitive member), the wear resistance of the photoconductor is improved. Further, the polyarylate resin (1) is imparted with an appropriate polarity by the divalent group represented by the chemical formula (Y1), (Y2), or (Y3) having an —OCO— group. As a result, the solubility of the polyarylate resin (1) in the solvent for forming the photosensitive layer and the polyarylate resin (1) in the material contained in the photosensitive layer (more specifically, a charge generator, a hole transporting agent, etc.) ) Improves compatibility. By improving the solubility and compatibility, when the polyarylate resin (1) is contained in the photosensitive layer, a uniform photosensitive layer is formed and the sensitivity characteristics of the photoconductor are improved. Further, by improving the solubility and compatibility, the dispersibility of the polyarylate resin (1) in the coating liquid for forming the photosensitive layer is enhanced, and the gelation of the coating liquid is suppressed. As a result, the liquid life characteristics of the photoconductor are improved. As for the liquid life characteristic, even when the coating liquid for forming the photosensitive layer is stored for a while without being used immediately after production, the dispersibility of the components contained in the coating liquid can be maintained, and the coating liquid can be used. It is a characteristic that gelation is unlikely to occur.

The polyarylate resin (1) may be described as a repeating unit represented by the general formula (1A) and a repeating unit represented by the general formula (1B) (hereinafter, each of which is referred to as a repeating unit (1A) and (1B). There is). R ¹ , R ² , and X in the general formula (1A) and Y in the general formula (1B) are synonymous with R ¹ , R ² , X, and Y in the general formula (1), respectively. ..

As already described, in the general formula (1), m represents a number of 50 or more and less than 100. Since m is not 100, the polyarylate resin (1) is a copolymer having both the repeating units (1A) and (1B). m preferably represents a number of 60 or more and 95 or less, more preferably 70 or more and 90 or less, and particularly preferably 80. m indicates a percentage (unit:%) of the number of repeating units (1A) with respect to the total number of repeating units (1A) and (1B). m can be calculated from the ratio of peaks characteristic of each repeating unit in the obtained ¹ H-NMR spectrum obtained by measuring the ¹ H-NMR spectrum of the polyarylate resin (1) using a proton nuclear magnetic resonance spectrometer. .. In order to improve wear resistance, sensitivity characteristics, and liquid life characteristics, the polyarylate resin (1) preferably has only repeating units (1A) and (1B) as repeating units.

In the general formula (X1), t preferably represents 2.

In the general formula (X2), R ³ represents a hydrogen atom and R ⁴ represents a methyl group, an ethyl group, or an alkyl group having 3 carbon atoms, R ³ represents a methyl group and R ⁴ represents an ethyl group or It is preferable that an alkyl group having 3 carbon atoms is represented, or R ³ represents an ethyl group and R ⁴ represents an alkyl group having 3 carbon atoms. It is more preferable that R ³ represents a hydrogen atom and R ⁴ represents a methyl group, or R ³ represents a methyl group and R ⁴ represents an ethyl group.

The bond represented by * in the general formulas (X1) and (X2) is bonded to the carbon atom to which X in the general formula (1) is bonded. The bond represented by * in the chemical formulas (Y1), (Y2), and (Y3) is bonded to the carbon atom to which Y in the general formula (1) is bonded.

In the general formula (1), R ¹ and R ² preferably represent a methyl group, and X preferably represents a divalent group represented by the general formula (X1).

A preferred embodiment when R ¹ and R ² in the general formula (1) represent a methyl group is as follows. That is, it is preferable that X represents a divalent group represented by the general formula (X1). In the general formula (X1), t preferably represents 2. As already described, Y represents a divalent group represented by the chemical formula (Y1), (Y2), or (Y3).

In a more preferred embodiment in which R ¹ and R ² in the general formula (1) represent a methyl group, the general formula (1) is the general formula (1-1), (1-2), or (1) described later. 1-3).

In the general formula (1), it is also preferable that R ¹ and R ² represent a hydrogen atom, and X represents a divalent group represented by the general formula (X2).

A preferred embodiment when R ¹ and R ² in the general formula (1) represent a hydrogen atom is as follows. That is, it is preferable that X represents a divalent group represented by the general formula (X2). In the general formula (X2), R ³ preferably represents a hydrogen atom. R ⁴ preferably represents a methyl group. Y preferably represents a divalent group represented by the chemical formula (Y3).

Another preferred embodiment when R ¹ and R ² in the general formula (1) represent a hydrogen atom is as follows. That is, it is preferable that X represents a divalent group represented by the general formula (X2). In the general formula (X2), R ³ preferably represents a methyl group. R ⁴ preferably represents an ethyl group. Y preferably represents a divalent group represented by the chemical formula (Y3).

In a more preferred embodiment when R ¹ and R ² in the general formula (1) represent a hydrogen atom, the general formula (1) is the general formula (1-4) or (1-5) described later. ..

Preferable examples of the polyarylate resin (1) are polyarylate resins represented by the general formulas (1-1) to (1-5) (hereinafter, each of which is a polyarylate resin (1-1) to (1-). 5) may be described). M ₁ in the general formula (1-1), m ₂ in the general formula (1-2), m ₃ in the general formula (1-3), m ₄ in the general formula (1-4), and general. Each of m ₅ in the formula (1-5) is synonymous with m in the general formula (1).

The viscosity average molecular weight of the polyarylate resin (1) is preferably 10,000 or more, more preferably 20,000 or more, further preferably 30,000 or more, and 40,000 or more. Is particularly preferred. When the viscosity average molecular weight of the polyarylate resin (1) is 10,000 or more, the wear resistance of the photoconductor can be improved. On the other hand, the viscosity average molecular weight of the polyarylate resin (1) is preferably 80,000 or less, more preferably 70,000 or less. When the viscosity average molecular weight of the polyarylate resin (1) is 80,000 or less, the polyarylate resin (1) is easily dissolved in the solvent for forming the photosensitive layer. The polyarylate resin (1) may be, for example, a random copolymer, an alternate copolymer, a periodic copolymer, or a block copolymer.

Hereinafter, a method for producing the polyarylate resin (1) will be described. Examples of the method for producing the polyarylate resin (1) include a method of polycondensing a bisphenol for forming a bisphenol-derived repeating unit and a dicarboxylic acid for forming a dicarboxylic acid-derived repeating unit. For the polycondensation, a known synthesis method (for example, solution polymerization, melt polymerization, or interfacial polymerization) can be adopted.

Examples of the bisphenol for constituting the bisphenol-derived repeating unit of the polyarylate resin (1) include compounds represented by the general formulas (BP-1) and (BP-2). Examples of the dicarboxylic acid for constituting the dicarboxylic acid-derived repeating unit of the polyarylate resin (1) include a compound represented by the general formula (DC). R ¹ , R ² , and X in the general formula (BP-1) and Y in the general formula (BP-2) are R ¹ , R ² , X, and Y in the general formula (1), respectively. Is synonymous with.

Bisphenol may be used by derivatizing it with aromatic diacetate. The dicarboxylic acid may be derivatized and used. Examples of dicarboxylic acid derivatives include dicarboxylic acid dichloride, dicarboxylic acid dimethyl ester, dicarboxylic acid diethyl ester, and dicarboxylic acid anhydride. The dicarboxylic acid dichloride is a compound in which the two "-C (= O) -OH" groups of the dicarboxylic acid are each substituted with "-C (= O) -Cl" groups.

In the polycondensation of bisphenol and dicarboxylic acid, one or both of the base and the catalyst may be added. Examples of bases include sodium hydroxide. Examples of catalysts include benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine, and trimethylamine.

<Second Embodiment: Photoreceptor>
The second embodiment of the present invention relates to a photoconductor. The photoconductor of the second embodiment includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generator, a hole transport agent, and a binder resin. The photoconductor is, for example, a single-layer electrophotographic photosensitive member (hereinafter, may be referred to as a single-layer type photosensitive member) or a laminated electrophotographic photosensitive member (hereinafter, may be referred to as a laminated photosensitive member). Is.

(Laminated photoconductor)
Hereinafter, the laminated photoconductor 1 as an example of the photoconductor will be described with reference to FIGS. 1 to 3. 1 to 3 show partial cross-sectional views of the laminated photoconductor 1, respectively.

As shown in FIG. 1, the laminated photoconductor 1 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 includes a charge generation layer 3a and a charge transport layer 3b. That is, the laminated photoconductor 1 includes a charge generation layer 3a and a charge transport layer 3b as the photosensitive layer 3. The charge generation layer 3a is, for example, a single layer. The charge transport layer 3b is, for example, one layer.

As shown in FIG. 1, a charge generation layer 3a may be provided on the conductive substrate 2, and a charge transport layer 3b may be provided on the charge generation layer 3a. Alternatively, as shown in FIG. 2, the charge transport layer 3b may be provided on the conductive substrate 2, and the charge generation layer 3a may be provided on the charge transport layer 3b.

As shown in FIG. 3, the laminated photoconductor 1 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2 and the photosensitive layer 3. The intermediate layer 4 is provided between the conductive substrate 2 and the photosensitive layer 3. As shown in FIGS. 1 and 2, in the laminated photoconductor 1, the photosensitive layer 3 may be provided directly on the conductive substrate 2. Alternatively, as shown in FIG. 3, in the laminated photoconductor 1, the photosensitive layer 3 may be provided on the conductive substrate 2 via the intermediate layer 4. When the laminated photoconductor 1 includes the intermediate layer 4, as shown in FIG. 3, the intermediate layer 4 is provided on the conductive substrate 2, the charge generation layer 3a is provided on the intermediate layer 4, and the charge generation layer 3a is provided. A charge transport layer 3b may be provided on top. Alternatively, the intermediate layer 4 may be provided on the conductive substrate 2, the charge transport layer 3b may be provided on the intermediate layer 4, and the charge generation layer 3a may be provided on the charge transport layer 3b.

The laminated photoconductor 1 may further include a protective layer 5 (see FIG. 6) in addition to the conductive substrate 2 and the photosensitive layer 3. The protective layer 5 is provided on the photosensitive layer 3. As shown in FIGS. 1 to 3, the photosensitive layer 3 (for example, the charge transport layer 3b or the charge generating layer 3a) may be provided as the outermost surface layer of the laminated photoconductor 1. Alternatively, the protective layer 5 may be provided as the outermost surface layer of the laminated photoconductor 1.

As shown in FIG. 1, it is preferable that the photosensitive layer 3 (preferably the charge transport layer 3b) is provided as the outermost surface layer of the laminated photosensitive member 1. It is more preferable that the charge transport layer 3b is a single layer and is provided as the outermost surface layer of the laminated photoconductor 1. By providing the charge transport layer 3b containing the polyarylate resin (1) as the outermost surface layer, the wear resistance of the laminated photoconductor 1 can be further improved.

The charge generating layer 3a contains a charge generating agent. The charge generation layer 3a may contain a base resin, if necessary. The charge generation layer 3a may contain an additive, if necessary. The thickness of the charge generation layer 3a is not particularly limited, but is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 3 μm or less.

The charge transport layer 3b contains a hole transport agent and a binder resin. The charge transport layer 3b may contain an additive, if necessary. The thickness of the charge transport layer 3b is not particularly limited, but is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less. The laminated photoconductor 1 has been described above with reference to FIGS. 1 to 3.

(Single-layer photoconductor)
Next, the single-layer type photoconductor 10 as an example of the photoconductor will be described with reference to FIGS. 4 to 6. 4 to 6 show partial cross-sectional views of the single-layer photoconductor 10, respectively.

As shown in FIG. 4, the single-layer photoconductor 10 includes, for example, a conductive substrate 2 and a photosensitive layer 3. The photosensitive layer 3 provided in the single-layer type photosensitive member 10 is a single layer. Hereinafter, the "single-layer photosensitive layer 3" may be referred to as a "single-layer photosensitive layer 3c".

As shown in FIG. 5, the single-layer type photosensitive member 10 may further include an intermediate layer 4 (undercoat layer) in addition to the conductive substrate 2 and the single-layer type photosensitive layer 3c. The intermediate layer 4 is provided between the conductive substrate 2 and the single-layer photosensitive layer 3c. As shown in FIG. 4, the single-layer photosensitive layer 3c may be provided directly on the conductive substrate 2. Alternatively, as shown in FIG. 5, the single-layer photosensitive layer 3c may be provided on the conductive substrate 2 via the intermediate layer 4.

As shown in FIG. 6, the single-layer photosensitive member 10 may further include a protective layer 5 in addition to the conductive substrate 2 and the single-layer photosensitive layer 3c. The protective layer 5 is provided on the single-layer photosensitive layer 3c. As shown in FIGS. 4 and 5, the single-layer type photosensitive layer 3c may be provided as the outermost surface layer of the single-layer type photosensitive member 10. Alternatively, as shown in FIG. 6, the protective layer 5 may be provided as the outermost surface layer of the single-layer type photoconductor 10.

As shown in FIGS. 4 and 5, it is preferable that the photosensitive layer 3 (more specifically, the single-layer type photosensitive layer 3c) is provided as the outermost surface layer of the single-layer type photosensitive member 10. By providing the single-layer type photosensitive layer 3c containing the polyarylate resin (1) as the outermost surface layer, the wear resistance of the single-layer type photosensitive member 10 can be further improved.

The single-layer photosensitive layer 3c contains a charge generator, a hole transport agent, and a binder resin. The single-layer photosensitive layer 3c may further contain an electron transporting agent, if necessary. The single-layer photosensitive layer 3c may contain an additive, if necessary.

The thickness of the single-layer photosensitive layer 3c is not particularly limited, but is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. The single-layer photoconductor 10 has been described above with reference to FIGS. 4 to 6.

(Binder resin)
The binder resin contains the polyarylate resin (1) described in the first embodiment. When the photosensitive layer contains the polyarylate resin (1) as the binder resin, the abrasion resistance, sensitivity characteristics, and liquid life characteristics of the photoconductor are improved.

The photosensitive layer may contain only one type of polyarylate resin (1) as the binder resin, or may contain two or more types of polyarylate resin (1). Further, the photosensitive layer may contain only the polyarylate resin (1) as the binder resin, and may further contain a binder resin other than the polyarylate resin (1) (hereinafter, may be referred to as another binder resin). It may be contained. Examples of other binder resins include thermoplastic resins (more specifically, polyarylate resins other than the polyarylate resin (1), polycarbonate resins, styrene resins, styrene-butadiene copolymers, and styrene-acrylonitrile co-weights. Combined, styrene-maleic acid copolymer, styrene-acrylic acid copolymer, acrylic copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer, chloride Vinyl-vinyl acetate copolymer, polyester resin, alkyd resin, polyamide resin, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyvinyl acetal resin, and polyether resin), thermosetting resin (more Specifically, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, and other crosslinkable thermosetting resins), and photocurable resin (more specifically, epoxy-acrylic acid-based resin). , And urethane-acrylic acid-based copolymer).

(Hole transport agent)
Examples of the hole transporting agent include triphenylamine derivatives, diamine derivatives (for example, N, N, N', N'-tetraphenylbenzidine derivatives, N, N, N', N'-tetraphenylphenylenediamine derivatives, and the like. N, N, N', N'-tetraphenylnaphthylene diamine derivative, N, N, N', N'-tetraphenylphenanthrylene diamine derivative, and di (aminophenylethenyl) benzene derivative), oxadiazole System compounds (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), styryl compounds (eg, 9- (4-diethylaminostyryl) anthracene), carbazole compounds (eg, 9- (4-diethylaminostyryl) anthracene). For example, polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (eg, 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline), hydrazone compounds, indol compounds, oxazole compounds, isooxazole compounds, thiazole. Examples thereof include a system compound, a thiadiazol system compound, an imidazole system compound, a pyrazole system compound, and a triazole system compound. The photosensitive layer may contain only one kind of hole transporting agent, or may contain two or more kinds of hole transporting agents.

Preferable examples of the hole transporting agent include compounds represented by the general formulas (20), (21), and (22) (hereinafter, the hole transporting agents (20), (21), and (hereinafter, respectively). 22) may be described). Since the photosensitive layer contains the hole transporting agent (20), (21), or (22) together with the polyarylate resin (1), the wear resistance of the photoconductor is not impaired without impairing the charging characteristics of the photoconductor. , Sensitivity characteristics, and liquid life characteristics can be further improved.

In the general formula (20), R ²¹ and R ²² independently represent an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms. R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ each independently have a hydrogen atom, an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or one or more carbon atoms. Represents 8 or less alkoxy groups. a1 and a2 each independently represent an integer of 0 or more and 5 or less.

In the general formula (20), when a1 represents an integer of 2 or more and 5 or less, the plurality of R ^21s may represent the same group or different groups. When a2 represents an integer of 2 or more and 5 or less, the plurality of R ^22s may represent the same group or different groups.

In the general formula (20), R ²¹ and R ²² each independently preferably represent an alkyl group having 1 or more and 8 or less carbon atoms, and more preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. , It is more preferable to represent a methyl group. It is preferable that R ²³ and R ²⁴ each independently represent a phenyl group or a hydrogen atom. R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ can each independently represent a hydrogen atom, an alkyl group having 1 or more and 8 or less carbon atoms, or an alkoxy group having 1 or more and 8 or less carbon atoms. preferable. The alkyl group represented by R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ having 1 or more and 8 or less carbon atoms is preferably an alkyl group having 1 or more and 6 or less carbon atoms, and is preferably a methyl group, an ethyl group, or an ethyl group. The n-butyl group is more preferable. As the alkoxy group represented by R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , and R ²⁹ having 1 or more and 8 or less carbon atoms, an alkoxy group having 1 or more and 3 or less carbon atoms is preferable, and a methoxy group is more preferable. It is preferable that a1 and a2 independently represent 0 or 1, respectively.

In the general formula (21), R ³¹ , R ³² , R ³³ , R ³⁴ , R ³⁵ , and R ³⁶ each independently represent an alkyl group or a phenyl group having 1 or more and 8 or less carbon atoms. R ³⁷ and R ³⁸ each independently represent a hydrogen atom, an alkyl group having 1 or more carbon atoms and 8 or less carbon atoms, or a phenyl group. b1, b2, b3, and b4 each independently represent an integer of 0 or more and 5 or less. b5 and b6 each independently represent an integer of 0 or more and 4 or less. d and e independently represent 0 or 1, respectively.

In the general formula (21), when b1 represents an integer of 2 or more and 5 or less, the plurality of R ^31s may represent the same group or different groups. When b2 represents an integer of 2 or more and 5 or less, the plurality of R ^32s may represent the same group or different groups. When b3 represents an integer of 2 or more and 5 or less, the plurality of R ^33s may represent the same group or different groups. When b4 represents an integer of 2 or more and 5 or less, the plurality of R ^34s may represent the same group or different groups. When b5 represents an integer of 2 or more and 4 or less, the plurality of R ^35s may represent the same group or different groups. When b6 represents an integer of 2 or more and 4 or less, the plurality of R ^36s may represent the same group or different groups.

In the general formula (21), R ³¹ to R ³⁶ each independently preferably represent an alkyl group having 1 or more and 8 or less carbon atoms, and more preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. , Methyl group or ethyl group is more preferable. R ³⁷ and R ³⁸ preferably represent a hydrogen atom. It is preferable that b1, b2, b3, and b4 each independently represent an integer of 0 or more and 2 or less. b5 and b6 preferably represent 0.

In the general formula (22), R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ , and R ⁴⁶ each independently have an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or 1 carbon atom. Represents an alkoxy group of 8 or more and 8 or less. f1, f2, f4, and f5 each independently represent an integer of 0 or more and 5 or less. f3 and f6 each independently represent an integer of 0 or more and 4 or less.

In the general formula (22), when f1 represents an integer of 2 or more and 5 or less, the plurality of R ^41s may represent the same group or different groups. When f2 represents an integer of 2 or more and 5 or less, the plurality of R ^42s may represent the same group or different groups. When f4 represents an integer of 2 or more and 5 or less, the plurality of R ^44s may represent the same group or different groups. When f5 represents an integer of 2 or more and 5 or less, the plurality of R ^45s may represent the same group or different groups. When f3 represents an integer of 2 or more and 4 or less, the plurality of R ^43s may represent the same group or different groups. When f6 represents an integer of 2 or more and 4 or less, the plurality of R ^46s may represent the same group or different groups.

In the general formula (22), R ⁴¹ to R ⁴⁶ each independently preferably represent an alkyl group having 1 or more and 8 or less carbon atoms, and more preferably represent an alkyl group having 1 or more and 3 or less carbon atoms. , Methyl group or ethyl group is more preferable. It is preferable that f1, f2, f4, and f5 each independently represent an integer of 0 or more and 2 or less. It is preferable that f3 and f6 represent 0. The diphenylaminophenylethenyl group having R44, ^R45 , and ^R46 can be attached to the ^paraposition of the phenyl group with respect to the diphenylaminophenylethenyl group having ^R41 , ^R42 , and ^R43 . preferable.

As a more preferable example of the hole transporting agent, the compounds represented by the chemical formulas (HTM-1) to (HTM-8) (hereinafter, each of them is referred to as a hole transporting agent (HTM-1) to (HTM-8)). May be described). The hole transport agents (HTM-1) to (HTM-6) are suitable examples of the hole transport agents (20), respectively. The hole transport agent (HTM-7) is a good example of the hole transport agent (21). The hole transport agent (HTM-8) is a good example of the hole transport agent (22).

The hole transport agent can be a hole transport agent (20) in which R ²³ and R ²⁴ represent a phenyl group. Further, the hole transporting agent may be a hole transporting agent (HTM-6). Such a hole transporting agent tends to cause gelation of the coating liquid when it is contained in the coating liquid for forming the photosensitive layer. However, since the coating liquid contains the polyarylate resin (1), gelation of the coating liquid is suitably suppressed even when such a hole transporting agent is contained.

When the photoconductor is a laminated photoconductor, the content of the hole transporting agent is preferably 10 parts by mass or more and 200 parts by mass or less, and 20 parts by mass or more and 100 parts by mass or less, with respect to 100 parts by mass of the binder resin. It is more preferably 40 parts by mass or more and 60 parts by mass or less. When the photoconductor is a single-layer photoconductor, the content of the hole transport agent is preferably 50 parts by mass or more and 200 parts by mass or less, and 50 parts by mass or more and 70 parts by mass with respect to 100 parts by mass of the binder resin. More preferably, it is less than or equal to a part.

(Charge generator)
Examples of the charge generator include phthalocyanine pigments, perylene pigments, bisazo pigments, trisazo pigments, dithioketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaline pigments, indigo pigments, azurenium pigments, and cyanine. Pigments, powders of inorganic photoconductive materials (eg, selenium, selenium-tellu, selenium-arsenide, cadmium sulfide, and amorphous silicon), pyrylium pigments, anthanthrone pigments, triphenylmethane pigments, sulene pigments, toluidin pigments. , Pyrazoline pigments, and quinacridone pigments. The photosensitive layer may contain only one type of charge generator, or may contain two or more types of charge generator.

The phthalocyanine pigment is a pigment having a phthalocyanine structure. Examples of the phthalocyanine pigment include non-metallic phthalocyanine and metallic phthalocyanine. Examples of the metallic phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine. Metal-free phthalocyanine is represented by the chemical formula (CGM-1). Titanyl phthalocyanine is represented by the chemical formula (CGM-2).

The phthalocyanine pigment may be crystalline or amorphous. Examples of the crystal of the non-metal phthalocyanine include an X-type crystal of the non-metal phthalocyanine (hereinafter, may be referred to as an X-type non-metal phthalocyanine). Examples of the crystals of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter, each may be referred to as α-type, β-type, and Y-type titanyl phthalocyanine).

For example, for a digital optical image forming apparatus (for example, a laser beam printer or a facsimile using a light source such as a semiconductor laser), it is preferable to use a photoconductor having sensitivity in a wavelength region of 700 nm or more. Since it has a high quantum yield in the wavelength region of 700 nm or more, the phthalocyanine pigment is preferable, the metal-free phthalocyanine or the titanyl phthalocyanine is more preferable, the titanyl phthalocyanine is further preferable, and the Y-type titanyl phthalocyanine is particularly preferable. ..

The Y-type titanyl phthalocyanine has a main peak at 27.2 ° of the Bragg angle (2θ ± 0.2 °) in the CuKα characteristic X-ray diffraction spectrum, for example. The main peak in the CuKα characteristic X-ray diffraction spectrum is the peak having the first or second highest intensity in the range where the Bragg angle (2θ ± 0.2 °) is 3 ° or more and 40 ° or less. Y-type titanyl phthalocyanine does not have a peak at 26.2 ° C. in the CuKα characteristic X-ray diffraction spectrum.

The CuKα characteristic X-ray diffraction spectrum can be measured by, for example, the following method. First, a sample (titanylphthalocyanine) is filled in a sample holder of an X-ray diffractometer (for example, "RINT (registered trademark) 1100" manufactured by Rigaku Co., Ltd.), and an X-ray tube Cu, tube voltage 40 kV, tube current 30 mA, The X-ray diffraction spectrum is measured under the condition that the wavelength of the CuKα characteristic X-ray is 1.542 Å. The measurement range (2θ) is, for example, 3 ° or more and 40 ° or less (start angle 3 °, stop angle 40 °), and the scanning speed is, for example, 10 ° / min. The main peak is determined from the obtained X-ray diffraction spectrum, and the Bragg angle of the main peak is read.

When the photoconductor is a laminated photoconductor, the content of the charge generator is preferably 10 parts by mass or more and 300 parts by mass or less, and 100 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the base resin. Is more preferable. When the photoconductor is a single-layer photoconductor, the content of the charge generating agent is preferably 0.1 part by mass or more and 50 parts by mass or less, and 0.5 part by mass with respect to 100 parts by mass of the binder resin. It is more preferably 30 parts by mass or less.

(Base resin)
The example of the base resin contained in the charge generation layer is the same as the example of the other binder resin contained in the charge transport layer.

(Additive)
Additives include, for example, UV absorbers, antioxidants, radical scavengers, singlet scavengers, softeners, surface modifiers, bulking agents, thickeners, dispersion stabilizers, waxes, donors, surfactants. Agents, plasticizers, sensitizers, electron acceptor compounds, and leveling agents. Examples of the antioxidant include a hindered phenol antioxidant.

(Combination of materials)
In order to improve the wear resistance, sensitivity characteristics, and liquid life characteristics of the photoconductor, the combination of the hole transporting agent and the binder resin is the combination No. 1 shown in Tables 1 and 2. Each of 1 to 80 is preferable. For the same reason, the combination of the hole transporting agent and the binder resin is the combination No. 1 shown in Tables 1 and 2. Each of 1 to 80, and the charge generator is preferably Y-type titanylphthalocyanine. For the same reason, the combination of the hole transporting agent and the binder resin is the combination No. 1 shown in Tables 1 and 2. It is more preferable that the additive contained in the charge transport layer, which is each of 1 to 80, is a hindered phenol antioxidant.

In Tables 1 and 2, "No." indicates "combination No.", "HTM" indicates "hole transporting agent", and "resin" indicates "polyarylate resin" which is a binder resin. The polyarylate resins (R-1) to (R-5) shown in Tables 1 and 2 will be described later in Examples.

(Conductive hypokeimenon)
The conductive substrate is not particularly limited, and at least the surface portion may be made of a material having conductivity. An example of a conductive substrate is a conductive substrate made of a conductive material. Another example of a conductive substrate is a conductive substrate coated with a conductive material. Examples of the conductive material include aluminum, iron, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass. Among these conductive materials, aluminum and aluminum alloys are preferable because the transfer of electric charges from the photosensitive layer to the conductive substrate is good.

The shape of the conductive substrate is appropriately selected according to the structure of the image forming apparatus. Examples of the shape of the conductive substrate include a sheet shape and a drum shape. Further, the thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

(Middle layer)
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (resin for the intermediate layer) used for the intermediate layer. The presence of the intermediate layer makes it possible to smooth the flow of current generated when the photoconductor is exposed and suppress the increase in resistance while maintaining an insulating state to the extent that leakage generation can be suppressed.

Inorganic particles include, for example, metal (eg, aluminum, iron, and copper) particles, metal oxide (eg, titanium oxide, alumina, zirconium oxide, tin oxide, and zinc oxide) particles, and non-metal oxides. Particles of (eg silica) can be mentioned.

The example of the resin for the intermediate layer is the same as the example of the other binder resin described above. In order to satisfactorily form the intermediate layer and the photosensitive layer, it is preferable that the resin for the intermediate layer is different from the binder resin contained in the photosensitive layer. The intermediate layer may contain additives. The example of the additive contained in the intermediate layer is the same as the example of the additive contained in the photosensitive layer.

(Manufacturing method of photoconductor)
As a method for manufacturing a photoconductor, an example of a method for manufacturing a laminated photoconductor and an example of a method for manufacturing a single-layer photoconductor will be described.

The method for producing a laminated photoconductor includes, for example, a charge generation layer forming step and a charge transport layer forming step. In the charge generation layer forming step, first, a coating liquid for forming the charge generation layer (hereinafter, may be referred to as a charge generation layer coating liquid) is prepared. The coating liquid for the charge generation layer is applied onto the conductive substrate. Next, at least a part of the solvent contained in the applied liquid for the charge generation layer is removed to form the charge generation layer. The coating liquid for the charge generating layer contains, for example, a charge generating agent, a base resin, and a solvent. Such a coating liquid for a charge generating layer is prepared by dissolving or dispersing a charge generating agent and a base resin in a solvent. The coating liquid for the charge generation layer may further contain additives, if necessary.

In the charge transport layer forming step, first, a coating liquid for forming the charge transport layer (hereinafter, may be referred to as a charge transport layer coating liquid) is prepared. The coating liquid for the charge transport layer is applied onto the charge generation layer. Next, at least a part of the solvent contained in the applied liquid for the charge transport layer is removed to form the charge transport layer. The coating liquid for the charge transport layer contains a hole transport agent, a binder resin, and a solvent. The coating liquid for the charge transport layer can be prepared by dissolving or dispersing the hole transport agent and the binder resin in a solvent. The coating liquid for the charge transport layer may further contain additives, if necessary.

The method for producing a single-layer photosensitive layer includes, for example, a single-layer photosensitive layer forming step. In the single-layer type photosensitive layer forming step, a coating liquid for forming the single-layer type photosensitive layer (hereinafter, may be referred to as a single-layer type photosensitive layer coating liquid) is prepared. The coating liquid for a single-layer photosensitive layer is applied onto a conductive substrate. Next, at least a part of the solvent contained in the coated liquid for the single-layer type photosensitive layer is removed to form the single-layer type photosensitive layer. The coating liquid for a single-layer photosensitive layer contains, for example, a charge generator, a hole transporting agent, a binder resin, and a solvent. The coating liquid for a single-layer photosensitive layer is prepared by dissolving or dispersing a charge generating agent, a hole transporting agent, and a binder resin in a solvent. The coating liquid for a single-layer photosensitive layer may further contain one or both of an electron transporting agent and an additive, if necessary.

The solvent contained in the coating liquid for a single-layer photosensitive layer, the coating liquid for a charge generating layer, and the coating liquid for a charge transport layer (hereinafter, these may be collectively referred to as a coating liquid) is used in the coating liquid. It is not particularly limited as long as each component contained can be dissolved or dispersed. Examples of the solvent include alcohols (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbons (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic hydrocarbons, etc. Hydrogen (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbons (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene, etc.), ethers (more specifically, dimethyl ether). , Diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.), ketones (more specifically, acetone, methyl ethyl ketone, cyclohexanone, etc.), esters (more specifically, ethyl acetate, methyl acetate, etc.), Included are dimethylformaldehyde, dimethylformamide, and dimethylsulfoxide.

The solvent contained in the coating liquid for the charge transport layer is preferably different from the solvent contained in the coating liquid for the charge generating layer. This is because when the coating liquid for the charge transport layer is applied onto the charge generation layer, it is preferable that the charge generation layer is not dissolved in the solvent of the coating liquid for the charge transport layer.

The coating liquid is prepared by mixing each component and dispersing them in a solvent. For mixing or dispersion, for example, a bead mill, a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser can be used.

The method of applying the coating liquid is not particularly limited as long as the coating liquid can be applied uniformly. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

Examples of the method for removing at least a part of the solvent contained in the coating liquid include heating, depressurization, or combined use of heating and depressurization. More specifically, a method of heat treatment (hot air drying) using a high temperature dryer or a vacuum dryer can be mentioned. The temperature of the heat treatment is, for example, 40 ° C. or higher and 150 ° C. or lower. The heat treatment time is, for example, 3 minutes or more and 120 minutes or less.

The method for producing the photoconductor may further include one or both of a step of forming an intermediate layer and a step of forming a protective layer, if necessary. A known method can be appropriately selected for the step of forming the intermediate layer and the step of forming the protective layer.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the scope of the examples.

<Synthesis of polyarylate resins (R-1) to (R-5)>
Each of the polyarylate resins (R-1) to (R-5) shown below was synthesized.
Polyarylate resin (R-1): Polyarylate resin (1-1) in which m ₁ in the general formula (1-1) is 80.
Polyarylate resin (R-2): Polyarylate resin (1-2) in which m ₂ in the general formula (1-2) is 80.
Polyarylate resin (R-3): Polyarylate resin (1-3) in which m ₃ in the general formula (1-3) is 80.
Polyarylate resin (R-4): Polyarylate resin (1-4) in which m ₄ in the general formula (1-4) is 80.
Polyarylate resin (R-5): Polyarylate resin (1-5) in which m ₅ in the general formula (1-5) is 80.

The compounds (BP-Y1), (BP-Y2), (BP-Y3), (BP-a), (BP-b), (BP-c), and (DC-a) described in the following description are They are represented by the following chemical formulas (BP-Y1), (BP-Y2), (BP-Y3), (BP-a), (BP-b), (BP-c), and (DC-a), respectively. ..

(Synthesis of polyarylate resin (R-1))
As a reaction vessel, a three-necked flask equipped with a thermometer, a three-way cock, and a dropping funnel was used. In a reaction vessel, compound (BP-a) (32.8 mmol), compound (BP-Y2) (8.2 mmol), p-tert-butylphenol (0.413 mmol), and sodium hydroxide (98). Millimole) and benzyltributylammonium chloride (0.384 mmol) were added. The air in the reaction vessel was replaced with argon gas. Water (300 mL) was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 50 ° C. for 1 hour. The contents of the reaction vessel were cooled to 10 ° C. to obtain an alkaline aqueous solution A.

Next, the dicarboxylic acid dichloride (32.4 mmol) of compound (DC-a) was dissolved in chloroform (150 mL). As a result, chloroform solution B was obtained.

Chloroform solution B was slowly added dropwise to the alkaline aqueous solution A over 110 minutes using a dropping funnel. While adjusting the temperature (liquid temperature) of the contents of the reaction vessel to 15 ± 5 ° C., the contents of the reaction vessel were stirred for 4 hours to proceed with the polymerization reaction. The upper layer (aqueous layer) of the contents of the reaction vessel was removed using a decant to obtain an organic layer. Then, ion-exchanged water (400 mL) was added to the Erlenmeyer flask. The obtained organic layer was further added into the Erlenmeyer flask. Chloroform (400 mL) and acetic acid (2 mL) were further added to the Erlenmeyer flask. The contents of the Erlenmeyer flask were stirred at room temperature (25 ° C.) for 30 minutes. The upper layer (water layer) of the contents of the Erlenmeyer flask was removed using a decant to obtain an organic layer. The obtained organic layer was washed with ion-exchanged water (1 L) using a separating funnel. Washing with ion-exchanged water was repeated 5 times to obtain an organic layer washed with water. Next, the organic layer washed with water was filtered to obtain a filtrate. The obtained filtrate was slowly added dropwise to methanol (1 L) to obtain a precipitate. The precipitate was removed by filtration. The removed precipitate was vacuum dried at a temperature of 70 ° C. for 12 hours. As a result, a polyarylate resin (R-1) was obtained.

(Synthesis of polyarylate resin (R-2))
The polyarylate resin (polyarylate resin (R-1) is synthesized by the same method as that of the polyarylate resin (R-1), except that the compound (BP-Y2) (8.2 mmol) is changed to the compound (BP-Y1) (8.2 mmol). R-2) was obtained.

(Synthesis of polyarylate resin (R-3))
The polyarylate resin (polyarylate resin (R-1) is synthesized by the same method as that of the polyarylate resin (R-1), except that the compound (BP-Y2) (8.2 mmol) is changed to the compound (BP-Y3) (8.2 mmol). R-3) was obtained.

(Synthesis of polyarylate resin (R-4))
Compound (BP-Y2) (8.2 mmol) and compound (BP-a) (32.8 mmol), compound (BP-Y3) (8.2 mmol) and compound (BP-b) (32.8). The polyarylate resin (R-4) was obtained by the same method as the synthesis of the polyallylate resin (R-1) except that the mixture was changed to millimole).

(Synthesis of polyarylate resin (R-5))
Compound (BP-Y2) (8.2 mmol) and compound (BP-a) (32.8 mmol), compound (BP-Y3) (8.2 mmol) and compound (BP-c) (32.8). Polyarylate resin (R-5) was obtained by the same method as the synthesis of polyallylate resin (R-1) except that the mixture was changed to millimole).

The viscosity average molecular weights of the obtained polyarylate resins (R-1) to (R-5) were all 50,500.

The ¹ H-NMR spectra of the obtained polyarylate resins (R-1) to (R-5) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., 600 MHz). Deuterated chloroform was used as the solvent. Tetramethylsilane (TMS) was used as the internal standard sample. As a representative example of the polyarylate resin (R-1) to (R-5), the ¹ H-NMR spectrum of the polyarylate resin (R-3) is shown in FIG. An enlarged view of the ¹ H-NMR spectrum shown in FIG. 7 in the vicinity of the range of 1.0 ppm or more and 2.5 ppm or less is shown in FIG. An enlarged view of the ¹ H-NMR spectrum shown in FIG. 7 in the vicinity of the range of 7.0 ppm or more and 8.3 ppm or less is shown in FIG. ¹ It was confirmed that the polyarylate resin (R-3) was obtained from the chemical shift read from the 1 H-NMR spectrum. The same method applies to the polyarylate resins (R-1), (R-2), (R-4), and (R-5), and the polyarylate resins (R-1), (R-2), (R). It was confirmed that -4) and (R-5) were obtained.

<Preparation of polyarylate resin used in comparative example>
As the polyarylate resin used in the comparative example, the polyarylate resin represented by the following chemical formulas (R-6C) and (R-7C) (hereinafter, each of which is a polyarylate resin (R-6C) and (R-7C)) May be described) was prepared. The number attached to the lower right of the repeating unit indicates the percentage (unit:%) of the number of the corresponding repeating units with respect to the total number of the repeating units contained in the polyarylate resin. The viscosity average molecular weights of the polyarylate resins (R-6C) and (R-7C) were both 50,500.

<Manufacturing of laminated photoconductor>
(Manufacturing of laminated photoconductor (A-1))
First, an intermediate layer was formed. Surface-treated titanium oxide (“Prototype SMT-A” manufactured by TAYCA Corporation, number average primary particle size 10 nm) was prepared. In SMT-A, titanium oxide was surface-treated with alumina and silica, and the surface-treated titanium oxide was further surface-treated with methylhydrogenpolysiloxane while being wet-dispersed. Next, 2 parts by mass of SMT-A and 1 part by mass of a polyamide resin ("Amilan (registered trademark) CM8000" manufactured by Toray Industries, Inc., a quaternary copolymerized polyamide resin of polyamide 6, polyamide 12, polyamide 66 and polyamide 610). , 10 parts by mass of methanol, 1 part by mass of butanol, and 1 part by mass of toluene were mixed for 5 hours using a bead mill to obtain a coating liquid for an intermediate layer. The coating liquid for the intermediate layer was filtered using a filter having an opening of 5 μm. Then, the coating liquid for the intermediate layer was applied to the surface of the conductive substrate by the dip coating method. As the conductive substrate, an aluminum drum-shaped support was used. Subsequently, the coated coating liquid for the intermediate layer was dried at 130 ° C. for 30 minutes to form an intermediate layer (film thickness: 2 μm) on the conductive substrate.

Next, a charge generation layer was formed. Specifically, 1.5 parts by mass of Y-type titanylphthalocyanine, which is a charge generator, 1.0 part by mass of polyvinyl acetal resin (“ESREC BX-5” manufactured by Sekisui Chemical Co., Ltd.), which is a base resin, and propylene glycol monomethyl. 40.0 parts by mass of ether and 40.0 parts by mass of tetrahydrofuran were mixed for 2 hours using a bead mill to obtain a coating liquid for a charge generation layer. The coating liquid for the charge generation layer was filtered using a filter having an opening of 3 μm. The obtained filtrate was applied onto the intermediate layer by the dip coating method and dried at 50 ° C. for 5 minutes. In this way, a charge generation layer (film thickness: 0.3 μm) was formed on the intermediate layer.

Next, a charge transport layer was formed. Specifically, 50 parts by mass of the hole transport agent (HTM-1), 100 parts by mass of the polyarylate resin (R-1) which is a binder resin, and a hindered phenol antioxidant (BASF Co., Ltd. "Irganox (registered)" Trademark) 1010 ”) 2 parts by mass, 350 parts by mass of tetrahydrofuran, and 350 parts by mass of toluene were mixed to obtain a coating liquid for a charge transport layer. The coating liquid for the charge transport layer was applied onto the charge generating layer by the dip coating method, and dried at 120 ° C. for 40 minutes. In this way, a charge transport layer (thickness: 20 μm) was formed on the charge generation layer to obtain a laminated photoconductor (A-1). In the laminated photoconductor (A-1), an intermediate layer was provided on the conductive substrate, a charge generation layer was provided on the intermediate layer, and a charge transport layer was provided on the charge generation layer.

(Manufacturing of laminated photoconductors (A-2) to (A-13) and (B-1) to (B-3))
The laminated photoconductors (A-2) to (A-13) are manufactured by the same method as for producing the laminated photoconductor (A-1) except that the hole transporting agent and the polyarylate resin shown in Table 3 are used. And (B-1) to (B-3) were each produced.

<Evaluation>
The photoconductors (more specifically, each of the laminated photoconductors (A-1) to (A-13) and (B-1) to (B-3)) were evaluated as shown below. ..

(Evaluation of charging characteristics)
The environment for evaluating the charging characteristics of the photoconductor was an environment with a temperature of 25 ° C. and a relative humidity of 50% RH. Using a drum sensitivity tester (manufactured by Gentec Co., Ltd.), the surface of the photoconductor was charged under the conditions that the charging current flowing through the charger was −10 μA and the rotation speed of the photoconductor was 31 rpm. The surface potential of the photoconductor after charging was measured. The measured surface potential was defined as the charging potential of the photoconductor (V ₀ , unit: −V). The charging potential of each photoconductor is shown in Table 3. When the charging potential is −700V or more and −650V or less, it is determined that the charging characteristics of the photoconductor are maintained.

(Evaluation of sensitivity characteristics)
The environment for evaluating the sensitivity characteristics of the photoconductor was an environment with a temperature of 25 ° C. and a relative humidity of 50% RH. The surface of the photoconductor was charged to −600 V using a drum sensitivity tester (manufactured by Gentec Co., Ltd.). Then, using a bandpass filter, monochromatic light (wavelength: 780 nm, exposure amount: 0.8 μJ / cm ² ) was taken out from the light of the halogen lamp and irradiated on the surface of the photoconductor. The surface potential of the photoconductor was measured 80 milliseconds after irradiation with monochromatic light. The measured surface potential was defined as the post-exposure potential ( _VL , unit: −V) of the photoconductor. The post-exposure potential of each photoconductor is shown in Table 3. The smaller the absolute value of the post-exposure potential, the better the sensitivity characteristics of the photoconductor.

(Evaluation of wear resistance)
The coating liquid for the charge transport layer prepared in the above <Manufacturing of laminated photoconductor> was applied to a polypropylene sheet (thickness: 0.3 mm) wound around an aluminum pipe (diameter: 78 mm). The applied coating liquid for the charge transport layer was dried at 120 ° C. for 40 minutes to prepare a polypropylene sheet on which the charge transport layer (thickness 30 μm) was formed. Subsequently, the charge transport layer was peeled off from the polypropylene sheet. The peeled charge transport layer was attached to a card-shaped member (“S-36” manufactured by Taber Co., Ltd.). The mass MA of the card _- shaped member to which the charge transport layer was attached was measured. Next, a card-shaped member was attached to the rotary table of the rotary ablation tester (Toyo Seiki Seisakusho Co., Ltd.). Then, the rotary table was rotated 1000 times at a rotation speed of 60 rpm with a wear ring (“CS-10” manufactured by Taber Co., Ltd.) having a load of 500 gf placed on the photosensitive layer on the card-shaped member. In this way, the charge transport layer on the rotary table was worn. After wear, the mass MB of the card _- shaped member to which the charge transport layer was attached was measured again. Then, the wear loss (= _{MA -} MB, unit: mg), which is the mass change of the charge transport layer before and after wear, was determined. The measured wear loss is shown in Table 3. The smaller the wear loss, the better the wear resistance of the photoconductor.

(Evaluation of liquid life characteristics)
The coating liquid for the charge transport layer prepared in the above <Manufacturing of laminated photoconductor> was allowed to stand for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH. After standing for 24 hours, the presence or absence of gelation of the coating liquid for the charge transport layer was visually confirmed. From the confirmation results, the liquid life characteristics were evaluated based on the following criteria. The evaluation results are shown in Table 3.
Evaluation A: The coating liquid for the charge transport layer did not gel.
Evaluation B: The coating liquid for the charge transport layer gelled.

In Table 3, "HTM" indicates a hole transporting agent, and "resin" indicates a polyarylate resin which is a binder resin.

The wear resistance was evaluated using the coating liquid for the charge transport layer immediately after preparation, and the liquid life characteristics were evaluated using the coating liquid for the charge transport layer 24 hours after the preparation. Regarding the laminated photoconductors (B-2) and (B-3), the evaluation of the liquid life characteristics was B, that is, the coating liquid for the charge transport layer 24 hours after the preparation was gelled, but immediately after the preparation. The coating liquid for the charge transport layer was not gelled, and the charge transport layer could be formed to evaluate the wear resistance.

As shown in Table 3, the photosensitive layers of the laminated photoconductors (A-1) to (A-13) are polyarylate resin (1) (more specifically, polyarylate resin (R-1) to (). It contained one of R-5)). On the other hand, the photosensitive layers of the laminated photoconductors (B-1) to (B-3) contained the polyarylate resin (R-6C) or (R-7C), but the polyarylate resin (R-6C). ) And (R-7C) were not polyarylate resins included in the general formula (1). Therefore, the wear resistance and the liquid life characteristics of the laminated photoconductors (A-1) to (A-13) are superior to those of the laminated photoconductors (B-2) and (B-3). rice field. Further, the sensitivity characteristics of the laminated photoconductors (A-1) to (A-13) were superior to those of the laminated photoconductors (B-1) and (B-2). Further, the laminated photoconductors (A-1) to (A-13) were able to improve wear resistance, sensitivity characteristics, and liquid life characteristics without impairing the charging characteristics. Further, the coating liquid for the charge transport layer containing the hole transport agent (HTM-6) tends to gel. However, it has been shown that even when such a hole transporting agent (HTM-6) is contained, gelation of the coating liquid for the charge transport layer can be suppressed by using the polyarylate resin (1). Was done.

From the above, the polyarylate resin of the present invention including the polyarylate resins (R-1) to (R-5) can improve the wear resistance and the sensitivity characteristics when contained in the photosensitive layer of the photoconductor. It was shown that the liquid life characteristics can be improved when it is contained in the coating liquid for the photosensitive layer of the photoconductor. Further, it was shown that the photoconductors of the present invention including the laminated photoconductors (A-1) to (A-13) are excellent in wear resistance, sensitivity characteristics, and liquid life characteristics.

The photoconductor according to the present invention can be used in an image forming apparatus.

1: Laminated photoconductor (laminated electrophotographic photosensitive member)
2: Conductive substrate 3: Photosensitive layer 3a: Charge generation layer 3b: Charge transport layer 3c: Single layer type photosensitive layer 10: Single layer type photosensitive member (single layer type electrophotographic photosensitive member)

Claims (10)

Polyarylate resin represented by the general formula (1).

(In the general formula (1),
R ¹ and R ² each independently represent a hydrogen atom or a methyl group.
X represents a divalent group represented by the general formula (X1) or (X2).
Y represents a divalent group represented by the chemical formula (Y1), (Y2), or (Y3).
m represents a number of 50 or more and less than 100. )

(In the general formula (X1), t represents 1 or 2, * represents a bond, and
In the general formula (X2), R ³ and R ⁴ represent a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, R ³ and R ⁴ represent groups different from each other, and * represents a bond. show. )

(In the chemical formulas (Y1), (Y2), and (Y3), * represents a bond.) The polyarylate resin according to claim 1, wherein in the general formula (1), R ¹ and R ² represent a methyl group, and X represents a divalent group represented by the general formula (X1). The polyarylate resin according to claim 1 or 2, wherein the general formula (1) is the general formula (1-1), (1-2), or (1-3).

(In the general formula (1-1), m ₁ represents a number of 50 or more and less than 100.
In the general formula (1-2), m ₂ represents a number of 50 or more and less than 100.
In the general formula (1-3), m ₃ represents a number of 50 or more and less than 100. ) The polyarylate resin according to claim 1, wherein in the general formula (1), R ¹ and R ² represent a hydrogen atom, and X represents a divalent group represented by the general formula (X2). The polyarylate resin according to claim 1 or 4, wherein the general formula (1) is the general formula (1-4) or (1-5).

(In the general formula (1-4), m ₄ represents a number of 50 or more and less than 100.
In the general formula (1-5), m ₅ represents a number of 50 or more and less than 100. ) With a conductive substrate and a photosensitive layer,
The photosensitive layer contains a charge generator, a hole transport agent, and a binder resin.
The binder resin is an electrophotographic photosensitive member containing the polyarylate resin according to any one of claims 1 to 5. The electrophotographic photosensitive member according to claim 6, wherein the hole transporting agent contains a compound represented by the general formula (20), (21), or (22).

(In the general formula (20), R ²¹ and R ²² each independently represent an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms, and R ²³ . ~ R ²⁹ each independently represents a hydrogen atom, an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms, and a1 and a2 independently represent 0. Represents an integer of 5 or more and 5 or less
In the general formula (21), R ³¹ to R ³⁶ each independently represent an alkyl group or a phenyl group having 1 or more and 8 or less carbon atoms, and R ³⁷ and R ³⁸ each independently represent a hydrogen atom. Represents an alkyl group or phenyl group having 1 or more and 8 or less carbon atoms, b1, b2, b3, and b4 each independently represent an integer of 0 or more and 5 or less, and b5 and b6 each independently represent 0. It represents an integer of 4 or more, and d and e independently represent 0 or 1, respectively.
In the general formula (22), R ⁴¹ to R ⁴⁶ independently represent an alkyl group having 1 or more and 8 or less carbon atoms, a phenyl group, or an alkoxy group having 1 or more and 8 or less carbon atoms, and f1 and f2. , F4, and f5 each independently represent an integer of 0 or more and 5 or less, and f3 and f6 each independently represent an integer of 0 or more and 4 or less. ) The hole transporting agent has chemical formulas (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), (HTM-7), and more. Or the electrophotographic photosensitive member according to claim 6 or 7, which comprises a compound represented by (HTM-8).

The electrophotographic photosensitive member according to any one of claims 6 to 8, wherein the photosensitive layer is provided as the outermost surface layer. The photosensitive layer includes a charge generating layer containing the charge generating agent and a charge transporting layer containing the hole transporting agent and the binder resin.
The electrophotographic photosensitive member according to any one of claims 6 to 9, wherein the charge transport layer is one layer and is provided as the outermost surface layer.

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