WO2018079118A1

WO2018079118A1 - Polyarylate resin and electrophotographic photoreceptor

Info

Publication number: WO2018079118A1
Application number: PCT/JP2017/033119
Authority: WO
Inventors: 東　潤; 健二北口
Original assignee: 京セラドキュメントソリューションズ株式会社
Priority date: 2016-10-31
Filing date: 2017-09-13
Publication date: 2018-05-03
Also published as: JP6753471B2; CN109803994A; JPWO2018079118A1

Abstract

A polyarylate resin includes repeating units represented by general formula (1) and repeating units represented by general formula (2). In general formulae (1) and (2), R¹ represents a hydrogen atom or a methyl group. In general formula (2), X represents a bivalent group represented by chemical formula (2A), (2B), (2C), or (2D). An electrophotographic photoreceptor (100) comprises an electroconductive substrate (101) and a photosensitive layer (102). The photosensitive layer (102) includes a charge generating agent, a hole transport agent, and a binder resin. The binder resin includes the polyarylate resin. [Compound 1] [Compound 2] [Compound 3]

Description

Polyarylate resin and electrophotographic photosensitive member

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

The electrophotographic photoreceptor is used in an electrophotographic image forming apparatus. As the electrophotographic photosensitive member, for example, an electrophotographic photosensitive member having a single photosensitive layer is used. The single photosensitive layer has a charge generation function and a charge transport function.

The surface layer of the electrophotographic photoreceptor described in Patent Document 1 contains, for example, a polyarylate resin obtained from a dihydric phenol component and a divalent carboxylic acid component shown in the following structural unit examples.

Japanese Patent Laid-Open No. 10-20514

However, in the electrophotographic photoreceptor described in Patent Document 1, it is difficult to suppress the occurrence of filming.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a polyarylate resin capable of suppressing the occurrence of filming of an electrophotographic photoreceptor when incorporated in a photosensitive layer. Another object of the present invention is to provide an electrophotographic photosensitive member that can suppress the occurrence of filming by containing such a polyarylate resin.

The polyarylate resin of the present invention contains a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2).

In the general formulas (1) and (2), R ¹ represents a hydrogen atom or a methyl group. In the general formula (2), X represents a divalent group represented by the chemical formula (2A), (2B), (2C) or (2D).

The electrophotographic photoreceptor of the present invention comprises a conductive substrate and a photosensitive layer. The photosensitive layer includes a charge generator, a hole transport agent, and a binder resin. The binder resin includes a polyarylate resin. The polyarylate resin includes a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2).

According to the polyarylate resin of the present invention, the filming of the electrophotographic photosensitive member can be suppressed when it is contained in the photosensitive layer. Moreover, according to the electrophotographic photosensitive member of the present invention, the occurrence of filming can be suppressed.

It is a fragmentary sectional view showing an example of an electrophotographic photosensitive member, and this electrophotographic photosensitive member contains polyarylate resin concerning an embodiment of the present invention. It is a fragmentary sectional view showing an example of an electrophotographic photosensitive member, and this electrophotographic photosensitive member contains polyarylate resin concerning an embodiment of the present invention. It is a fragmentary sectional view showing an example of an electrophotographic photosensitive member, and this electrophotographic photosensitive member contains polyarylate resin concerning an embodiment of the present invention. It is a fragmentary sectional view showing an example of an electrophotographic photosensitive member, and this electrophotographic photosensitive member contains polyarylate resin concerning an embodiment of the present invention. It is a fragmentary sectional view showing an example of an electrophotographic photosensitive member, and this electrophotographic photosensitive member contains polyarylate resin concerning an embodiment of the present invention. It is a fragmentary sectional view showing an example of an electrophotographic photosensitive member, and this electrophotographic photosensitive member contains polyarylate resin concerning an embodiment of the present invention. ¹ shows a ¹ H-NMR spectrum of a polyarylate resin represented by the chemical formula (PA-1). An enlarged view of the range of 6.90 ppm to 9.00 ppm of the ¹ H-NMR spectrum shown in FIG. 3 is shown. FIG. 4 shows an enlarged view of the range of 1.2 ppm to 4.5 ppm of the ¹ H-NMR spectrum shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

Hereinafter, a compound and its derivatives may be generically named by adding “system” after the compound name. In addition, when “polymer” is added after the compound name to indicate the polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

Hereinafter, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, 1 carbon atom Unless otherwise specified, an alkoxy group having 4 or less and a cycloalkane having 5 to 7 carbon atoms have the following meanings, respectively.

The alkyl group having 1 to 8 carbon atoms, the alkyl group having 1 to 6 carbon atoms and the alkyl group having 1 to 4 carbon atoms are each linear or branched and unsubstituted. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group Hexyl group, heptyl group or octyl group. Examples of the alkyl group having 1 to 6 carbon atoms are groups having 1 to 6 carbon atoms among the groups described as examples of alkyl groups having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms are groups having 1 to 4 carbon atoms among the groups described as examples of alkyl groups having 1 to 8 carbon atoms.

The alkoxy group having 1 to 8 carbon atoms and the alkoxy group having 1 to 4 carbon atoms are each linear or branched and unsubstituted. Examples of the alkoxy group having 1 to 8 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, pentyloxy, iso Examples include a pentyloxy group, a neopentyloxy group, a hexyloxy group, a heptyloxy group, and an octyloxy group. Examples of the alkoxy group having 1 to 4 carbon atoms are groups having 1 to 4 carbon atoms among the groups described as examples of the alkoxy group having 1 to 8 carbon atoms.

A cycloalkane having 5 to 7 carbon atoms is unsubstituted. Examples of the cycloalkane having 5 to 7 carbon atoms are cyclopentane, cyclohexane or cycloheptane.

<Polyarylate resin>
The present embodiment relates to a polyarylate resin. The polyarylate resin of this embodiment contains the repeating unit represented by General formula (1) and the repeating unit represented by General formula (2). Hereinafter, the polyarylate resin containing the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) may be referred to as a polyarylate resin (PA). Moreover, the repeating unit represented by General formula (1) and the repeating unit represented by General formula (2) may be described as a repeating unit (1) and a repeating unit (2), respectively.

In the general formulas (1) and (2), R ¹ represents a hydrogen atom or a methyl group. In general formula (2), X represents a divalent group represented by chemical formula (2A), (2B), (2C) or (2D).

The polyarylate resin (PA) of this embodiment has both a repeating unit (1) and a repeating unit (2). Therefore, when the polyarylate resin (PA) is contained in the photosensitive layer, filming of the electrophotographic photosensitive member (hereinafter sometimes referred to as a photosensitive member) can be suppressed. Filming is a phenomenon in which minute components adhere to and adhere to the surface of the photoreceptor. An example of the minute component is a toner component, and more specifically, the toner or an external additive released from the toner. Another example of the minute component is a non-toner component, and more specifically, a minute component (for example, paper dust) of the recording medium.

R ^{1 in} general formulas (1) and (2) both represents a hydrogen atom. Alternatively, R ¹ in the general formulas (1) and (2) each represents a methyl group. In order to improve the abrasion resistance and electrical characteristics (especially sensitivity characteristics) of the photoreceptor in addition to the filming resistance of the photoreceptor, R ¹ in the general formulas (1) and (2) is methyl, respectively. It is preferable to represent a group.

In order to improve the abrasion resistance and electrical characteristics (especially sensitivity characteristics) of the photoreceptor in addition to the filming resistance of the photoreceptor, X in the general formula (2) is represented by the general formulas (2A) and (2B). Or a divalent group represented by (2D).

A preferred example of the repeating unit (1) is a repeating unit represented by the chemical formula (1-1) or (1-2). Hereinafter, the repeating unit represented by the chemical formula (1-1) and the repeating unit represented by the chemical formula (1-2) may be referred to as repeating units (1-1) and (1-2), respectively. . A more preferred example of the repeating unit (1) is the repeating unit (1-1).

A preferred example of the repeating unit (2) is a repeating unit represented by the chemical formula (2-1), (2-2), (2-3) or (2-4). Hereinafter, the repeating units represented by chemical formulas (2-1), (2-2), (2-3) and (2-4) are represented by repeating units (2-1), (2-2), Sometimes described as (2-3) and (2-4). A more preferred example of the repeating unit (2) is the repeating unit (2-1), (2-2) or (2-3).

In order to improve the filming resistance, abrasion resistance and electrical characteristics (particularly sensitivity characteristics) of the photoreceptor, a polyarylate resin (PA) in which the repeating unit (1) and the repeating unit (2) are as follows: Is preferred.
Whether the repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-1);
The repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-2); or the repeating unit (1) is the repeating unit (1-1), The repeating unit (2) is the repeating unit (2-3).

A more preferred embodiment is a polyarylate resin (PA) in which the repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-3). According to the polyarylate resin (PA) having such a structure, it is possible to further improve the filming resistance, abrasion resistance and electrical characteristics (particularly sensitivity characteristics) of the photoreceptor. Further, when the polyarylate resin (PA) contains the repeating unit (2-3), the solubility of the polyarylate resin (PA) in the solvent for forming the photosensitive layer can be improved.

As another more preferable embodiment, a polyarylate resin (PA) in which the repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-1) or (2-2). ). A naphthylene group that the repeating unit (1-1) has, a divalent group that is represented by the chemical formula (2A) that the repeating unit (2-1) has, and a chemical formula (2B) that the repeating unit (2-2) has. Each of the divalent groups is bonded to a carbonyl group in a positional relationship in which the molecular chain of the polyarylate resin (PA) is linear. Since the polyarylate resin (PA) has a group that forms such a positional relationship, in addition to the filming resistance of the photoreceptor, the abrasion resistance and electrical characteristics (particularly sensitivity characteristics) of the photoreceptor are improved. Can do.

Polyarylate number n of the resin repeating units contained in the (PA) (1) The number n ₁ and repeating units (2) ₂ preferably satisfies the following calculation formula (i).
0.30 ≦ n ₁ / (n ₁ + n ₂ ) ≦ 0.70 (i)

"N ₁ / (n ₁ + n _2)" is to the sum of the number n ₂ of the polyarylate resin number n ₁ and repeating units of the repeating units (1) contained in (PA) (2), the repeating units (1 It represents the ratio of the number n ₁ of). When the ratio n ₁ / (n ₁ + n ₂ ) is 0.30 or more and 0.70 or less, the filming resistance, wear resistance, and electrical characteristics (particularly sensitivity characteristics) of the photoreceptor can be improved in a balanced manner. . The ratio n ₁ / (n ₁ + n ₂ ) is more preferably 0.40 or more and 0.60 or less, and further preferably 0.50.

Further, to the sum of the number n ₂ of the number n ₁ and repeating units of the repeating units (1) contained in the polyarylate resin (PA) (2), the ratio n ₂ / number n ₂ of the repeating units (2) ( n ₁ + n ₂ ) is preferably 0.30 or more and 0.70 or less, more preferably 0.40 or more and 0.60 or less, and still more preferably 0.50.

When the repeating unit (1) is the repeating unit (1-1) or (1-2), n ₁ represents the repeating unit (1-1) or (1-2) contained in the polyarylate resin (PA). It is equivalent to the number of When the repeating unit (2) is the repeating unit (2-1), (2-2), (2-3) or (2-4), n ₂ is a repeating unit contained in the polyarylate resin (PA). This corresponds to the number of units (2-1), (2-2), (2-3) or (2-4).

Each of the ratio n ₁ / (n ₁ + n ₂ ) and the ratio n ₂ / (n ₁ + n ₂ ) is not a value obtained from one molecular chain, but is a value of the polyarylate resin (PA) contained in the photosensitive layer. It is an average value of values obtained from the whole (a plurality of molecular chains). Each of the ratio n ₁ / (n ₁ + n ₂ ) and the ratio n ₂ / (n ₁ + n ₂ ) is measured, for example, by the following method. A ¹ H-NMR spectrum of polyarylate resin (PA) is measured using a proton nuclear magnetic resonance spectrometer. CDCl ₃ is used as a solvent, and tetramethylsilane (TMS) is used as an internal standard sample. From the ratio between the peak characteristic of the repeating unit (1) and the peak characteristic of the repeating unit (2) in the ¹ H-NMR spectrum of the polyarylate resin (PA) obtained, the ratio n ₁ / (n ₁ + n ₂ ) and the ratio n ₂ / (n ₁ + n ₂ ) are calculated.

The arrangement of the repeating units (1) and (2) in the polyarylate resin (PA) is not particularly limited. The polyarylate resin (PA) may be, for example, a random copolymer, an alternating copolymer, a periodic copolymer, or a block copolymer. The random copolymer is a copolymer in which repeating units (1) and repeating units (2) are randomly arranged. The alternating copolymer is a copolymer in which repeating units (1) and repeating units (2) are alternately arranged. The periodic copolymer is a copolymer in which one or more repeating units (1) and one or more repeating units (2) are periodically arranged. The block copolymer is a copolymer in which blocks formed from a plurality of repeating units (1) and blocks formed from a plurality of repeating units (2) are arranged.

The viscosity average molecular weight of the polyarylate resin (PA) is preferably 10,000 or more, more preferably 20,000 or more, further preferably 30,000 or more, and 50,000 or more. It is particularly preferred. When the viscosity average molecular weight of the polyarylate resin (PA) is 10,000 or more, the abrasion resistance of the binder resin is increased, and the charge transport layer or the single-layer type photosensitive layer is hardly worn. On the other hand, the viscosity average molecular weight of the binder resin is preferably 80,000 or less, and more preferably 60,000 or less. When the binder resin has a viscosity average molecular weight of 80,000 or less, the polyarylate resin (PA) is easily dissolved in the solvent for forming the charge transport layer or the solvent for forming the single-layer type photosensitive layer. There is a tendency that the formation of the layer-type photosensitive layer is facilitated.

The method for producing the polyarylate resin (PA) is not particularly limited. Examples of the method for producing the polyarylate resin (PA) include a method of polycondensing an aromatic diol and an aromatic dicarboxylic acid for constituting a repeating unit of the polyarylate resin. As the condensation polymerization method, a known synthesis method (more specifically, solution polymerization, melt polymerization, interfacial polymerization, or the like) can be employed.

Two types of aromatic dicarboxylic acids for synthesizing polyarylate resin (PA) are used. Hereinafter, the two types of aromatic dicarboxylic acids for synthesizing the polyarylate resin (PA) may be referred to as a first aromatic dicarboxylic acid and a second aromatic dicarboxylic acid, respectively.

The first aromatic dicarboxylic acid is a compound represented by the chemical formula (DC-1). A preferable example of the compound represented by the chemical formula (DC-1) is a compound represented by the chemical formula (DC-1-1) (hereinafter sometimes referred to as the compound (DC-1-1)). .

The second aromatic dicarboxylic acid is a compound represented by the chemical formula (DC-2), (DC-3), (DC-4) or (DC-5). Hereinafter, the compounds represented by the chemical formulas (DC-2), (DC-3), (DC-4) and (DC-5) are respectively represented by the compounds (DC-2), (DC-3), (DC -4) and (DC-5).

The first aromatic dicarboxylic acid and the second aromatic dicarboxylic acid may each be derivatized and used. Examples of derivatives of aromatic dicarboxylic acids are aromatic dicarboxylic acid dichlorides, aromatic dicarboxylic acid dimethyl esters, aromatic dicarboxylic acid diethyl esters or aromatic dicarboxylic acid anhydrides. Aromatic dicarboxylic acid dichloride is a compound in which two “—C (═O) —OH” groups of an aromatic dicarboxylic acid are each replaced with a “—C (═O) —Cl” group.

The aromatic diol for synthesizing the polyarylate resin (PA) is a compound represented by the chemical formulas (BP-1) and (BP-2) (hereinafter referred to as the compounds (BP-1) and (BP-2), respectively) May be described). The aromatic diol for synthesizing the polyarylate resin (PA) may be used after being transformed into an aromatic diacetate.

In the condensation polymerization of an aromatic diol and an aromatic dicarboxylic acid, one or both of a base and a catalyst may be added. The base and catalyst can be appropriately selected from known bases and catalysts. An example of a base is sodium hydroxide. Examples of catalysts are benzyltributylammonium chloride, ammonium chloride, ammonium bromide, quaternary ammonium salts, triethylamine or trimethylamine.

The polyarylate resin (PA) may contain only the repeating unit (1) and the repeating unit (2) as a repeating unit. Alternatively, the polyarylate resin (PA) may further include a repeating unit other than the repeating unit (1) and the repeating unit (2) in addition to the repeating unit (1) and the repeating unit (2). The total content of the repeating unit (1) and the repeating unit (2) contained in the polyarylate resin (PA) is 80% by number or more based on the total number of the repeating units contained in the polyarylate resin (PA). Is more preferable, 90% by number or more is more preferable, and 100% by number is particularly preferable. When the total content of the repeating unit (1) and the repeating unit (2) with respect to the total number of repeating units contained in the polyarylate resin (PA) is 100% by number, the polyarylate resin (PA) is a repeating unit ( 1) and repeating unit (2) only. The polyarylate resin (PA) according to this embodiment has been described above.

<Photoconductor>
Next, a photoconductor provided with a photosensitive layer containing a polyarylate resin (PA) according to this embodiment will be described. The photoreceptor includes a conductive substrate and a photosensitive layer. The photosensitive layer contains a charge generating agent, a hole transport agent, and a polyarylate resin (PA) as a binder resin. The photoreceptor may be a single-layer photoreceptor or a laminated photoreceptor.

(Multilayer photoconductor)
Hereinafter, the structure of the photoconductor 100 when the photoconductor 100 is a laminated type photoconductor will be described with reference to FIGS. 1A to 1C. FIG. 1A to FIG. 1C are partial cross-sectional views showing an example of a photoreceptor 100 (laminated photoreceptor), and this photoreceptor 100 includes a polyarylate resin according to this embodiment.

As shown in FIG. 1A, a laminated photoreceptor as the photoreceptor 100 includes, for example, a conductive substrate 101 and a photosensitive layer 102. The photosensitive layer 102 includes a charge generation layer 102a and a charge transport layer 102b. In other words, the multilayer photoreceptor includes the charge generation layer 102 a and the charge transport layer 102 b as the photosensitive layer 102.

As shown in FIG. 1B, in the stacked type photoconductor as the photoconductor 100, the charge transport layer 102b may be provided on the conductive substrate 101, and the charge generation layer 102a may be provided on the charge transport layer 102b. However, since the charge transport layer 102b is generally thicker than the charge generation layer 102a, the charge transport layer 102b is less likely to be damaged than the charge generation layer 102a. Therefore, in order to improve the abrasion resistance of the multilayer photoreceptor, as shown in FIG. 1A, a charge generation layer 102a is provided on the conductive substrate 101, and a charge transport layer 102b is provided on the charge generation layer 102a. It is preferable to be provided.

As shown in FIG. 1C, the multilayer photoreceptor as the photoreceptor 100 may include a conductive substrate 101, a photosensitive layer 102, and an intermediate layer 103 (undercoat layer). The intermediate layer 103 is provided between the conductive substrate 101 and the photosensitive layer 102. As shown in FIGS. 1A and 1B, the photosensitive layer 102 may be provided directly on the conductive substrate 101. As shown in FIG. 1C, the photosensitive layer 102 is interposed on the conductive substrate 101 with an intermediate layer 103 interposed therebetween. May be provided. Note that a protective layer 104 (see FIG. 2C) may be provided on the photosensitive layer 102.

The thicknesses of the charge generation layer 102a and the charge transport layer 102b are not particularly limited as long as the functions as the respective layers can be sufficiently expressed. The thickness of the charge generation layer 102a 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 thickness of the charge transport layer 102b is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

The charge generation layer 102a in the photosensitive layer 102 contains a charge generation agent. The charge generation layer 102a may contain a binder resin for a charge generation layer (hereinafter sometimes referred to as a base resin). The charge generation layer 102a may contain an additive as necessary.

The charge transport layer 102b in the photosensitive layer 102 contains a binder resin and a hole transport agent. The charge transport layer 102b may contain at least one of an electron acceptor compound and an additive as necessary.

In order to suppress the occurrence of filming, the charge transport layer 102b containing a polyarylate resin (PA) is preferably disposed as the outermost surface layer of the photoreceptor 100. The structure of the photoconductor 100 when the photoconductor 100 is a multilayer photoconductor has been described above with reference to FIGS. 1A to 1C.

(Single layer type photoreceptor)
Hereinafter, the structure of the photoconductor 100 when the photoconductor 100 is a single layer type photoconductor will be described with reference to FIGS. 2A to 2C. 2A to 2C are partial cross-sectional views showing another example (single-layer type photosensitive member) of the photosensitive member 100, and the photosensitive member 100 includes the polyarylate resin according to the present embodiment.

As shown in FIG. 2A, a single-layer type photoreceptor as the photoreceptor 100 includes, for example, a conductive substrate 101 and a photosensitive layer 102. The single layer type photoreceptor as the photoreceptor 100 includes a single layer type photosensitive layer 102 c as the photosensitive layer 102. The single-layer type photosensitive layer 102c is a single photosensitive layer 102.

As shown in FIG. 2B, the single layer type photoreceptor as the photoreceptor 100 may include a conductive substrate 101, a single layer type photosensitive layer 102c, and an intermediate layer 103 (undercoat layer). The intermediate layer 103 is provided between the conductive substrate 101 and the single-layer type photosensitive layer 102c. As shown in FIG. 2A, the photosensitive layer 102 may be provided directly on the conductive substrate 101, or as shown in FIG. 2B, the photosensitive layer 102 is provided on the conductive substrate 101 via the intermediate layer 103. May be.

As shown in FIG. 2C, the single layer type photoreceptor as the photoreceptor 100 may include a conductive substrate 101, a single layer type photosensitive layer 102c, and a protective layer 104. The protective layer 104 is provided on the single-layer type photosensitive layer 102c.

The thickness of the single-layer type photosensitive layer 102c is not particularly limited as long as the function as the single-layer type photosensitive layer can be sufficiently expressed. The thickness of the single-layer photosensitive layer 102c 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 type photosensitive layer 102c as the photosensitive layer 102 contains a charge generator, a binder resin, and a hole transport agent. The single layer type photosensitive layer 102c may further contain an electron transport agent. The single-layer type photosensitive layer 102c may contain an additive as necessary. When the photoreceptor 100 is a single-layer photoreceptor, the charge generator, the binder resin, the hole transport agent, and the components (for example, an electron transport agent or an additive) that are added as necessary are one layer. Of the photosensitive layer 102 (single-layer type photosensitive layer 102c).

In order to suppress the occurrence of filming, it is preferable that the single-layer type photosensitive layer 102 c containing polyarylate resin (PA) is disposed as the outermost surface layer of the photoreceptor 100. The structure of the photoconductor 100 when the photoconductor 100 is a single layer type photoconductor has been described above with reference to FIGS. 2A to 2C. Next, the laminated type photoreceptor and the single layer type photoreceptor will be described in more detail.

(Binder resin)
The binder resin includes the polyarylate resin (PA) described above. By including the polyarylate resin (PA) in the photosensitive layer, it is possible to suppress filming of the photoreceptor as described above.

The photosensitive layer may contain only polyarylate resin (PA) as a binder resin. Alternatively, the photosensitive layer may further contain a binder resin other than the polyarylate resin (PA) (hereinafter sometimes referred to as other binder resin) in addition to the polyarylate resin (PA) as the binder resin. Good. The content of the polyarylate resin (PA) is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass with respect to the mass of the binder resin. When the content of the polyarylate resin (PA) is 100% by mass with respect to the mass of the binder resin, the photosensitive layer (for example, the charge transport layer or the single-layer type photosensitive layer) is only the polyarylate resin (PA) as the binder resin. including.

Examples of other binder resins include thermoplastic resins, thermosetting resins, and photocurable resins. Examples of the thermoplastic resin include polycarbonate resins, polyarylate resins other than polyarylate resins (PA), styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic acid polymers, Styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, Examples of the resin include urethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyester resin, and polyether resin. As a thermosetting resin, a silicone resin, an epoxy resin, a phenol resin, a urea resin, or a melamine resin is mentioned, for example. Examples of the photocurable resin include epoxy acrylic acid (acrylic acid adduct of epoxy compound) or urethane-acrylic acid (acrylic acid adduct of urethane compound). These binder resins may be used individually by 1 type, and may be used in combination of 2 or more type.

(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, N, N, N ′, N′-tetraphenylnaphthylenediamine derivative, N, N, N ′, N′-tetraphenylphenanthrylenediamine derivative or di (aminophenylethenyl) benzene derivative), oxadiazole series Compounds (eg, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole), styryl compounds (eg, 9- (4-diethylaminostyryl) anthracene), carbazole compounds (eg, , Polyvinylcarbazole), organic polysilane compounds, pyrazoline compounds (for example, 1-phenyl-3- (p- Methylamino phenyl) pyrazoline), hydrazone compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compound, or triazole-based compounds. A hole transport agent may be used individually by 1 type, and may be used in combination of 2 or more type.

The hole transport agent may contain a compound represented by the general formula (10), (11) or (12) (hereinafter sometimes referred to as compound (10), (11) or (12)). preferable. Moreover, as a hole transport agent, hole transport agents other than the compounds (10), (11) and (12) (hereinafter, may be referred to as other hole transport agents) can also be used. Hereinafter, the compounds (10), (11) and (12), and other hole transport agents will be described.

Compound (10) is represented by the following general formula (10).

In general formula (10), R ¹⁰¹ and R ¹⁰⁸ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group optionally having an alkyl group having 1 to 8 carbon atoms. Or an alkoxy group having 1 to 8 carbon atoms. R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ may each independently have a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkyl group having 1 to 8 carbon atoms. A phenyl group or an alkoxy group having 1 to 8 carbon atoms is represented. Alternatively, two adjacent R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ may be bonded to represent a cycloalkane having 5 to 7 carbon atoms. ^R102 and ^R109 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms. b ₁ and b ₂ each independently represents an integer of 0 or more and 5 or less.

In general formula (10), the alkyl group having 1 to 8 carbon atoms represented by R ¹⁰¹ to R ¹⁰⁹ is preferably an alkyl group having 1 to 6 carbon atoms, and an alkyl group having 1 to 4 carbon atoms. Is more preferable, and a methyl group or an n-butyl group is still more preferable.

In general formula (10), the phenyl group represented by R ¹⁰¹ to R ¹⁰⁹ may have an alkyl group having 1 to 8 carbon atoms. The alkyl group having 1 to 8 carbon atoms in the phenyl group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and still more preferably a methyl group.

In general formula (10), the alkoxy group having 1 to 8 carbon atoms represented by R ¹⁰¹ to R ¹⁰⁹ is preferably an alkoxy group having 1 to 4 carbon atoms, and more preferably a methoxy group or an ethoxy group.

In the general formula (10), two adjacent ^ones of R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ may be bonded to each other to represent a cycloalkane having 5 to 7 carbon atoms. For example, R ¹⁰⁶ and R ¹⁰⁷ adjacent one of ^{^{^{R 103, R 104, R 105}}} , R 106 and R ¹⁰⁷ may be bonded to each other to form a 5 carbon atoms to 7 cycloalkane. When two adjacent ^ones of R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ are bonded to each other to form a cycloalkane having 5 to 7 carbon atoms, this cyclohexane having 5 to 7 carbon atoms The alkane is condensed with a phenyl group to which R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ are bonded to form a bicyclic fused ring group. In this case, the condensation site between the cycloalkane having 5 to 7 carbon atoms and the phenyl group may contain a double bond. Cycloalkane having 5 or more and 7 or less carbon atoms represented by bonding of two adjacent ^ones out of R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ is preferably cyclohexane.

When b ₁ represents an integer of 2 or more and 5 or less, the plurality of R ¹⁰² may be the same as or different from each other. When b ₂ represents an integer of 2 or more and 5 or less, the plurality of R ¹⁰⁹ may be the same as or different from each other. It is preferable that b ₁ and b ₂ each independently represent 0 or 1.

In general formula (10), R ¹⁰¹ and R ¹⁰⁸ preferably represent a phenyl group or a hydrogen atom having an alkyl group having 1 to 8 carbon atoms. R ¹⁰² and R ¹⁰⁹ preferably represent an alkyl group having 1 to 8 carbon atoms. R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ each preferably independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. . Alternatively, it is preferable that adjacent two of R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ and R ¹⁰⁷ are bonded to each other to form a cycloalkane having 5 to 7 carbon atoms. It is preferable that b ₁ and b ₂ each independently represent 0 or 1. In order to improve the filming resistance and wear resistance of the photoreceptor, it is more preferable that R ¹⁰¹ and R ¹⁰⁸ each represent a hydrogen atom in the general formula (10).

Preferred examples of the compound (10) include compounds represented by the chemical formula (HTM-1), (HTM-2), (HTM-3) or (HTM-4) (hereinafter referred to as the compound (HTM-1), (HTM-2), (HTM-3) or (HTM-4) may be mentioned).

Compound (11) is represented by the following general formula (11).

In general formula (11), R ¹¹¹ and R ¹¹² each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group. ^R113 , ^R114 , ^R115 , ^R116 , ^R117 and ^R118 each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group. d ₁ and d ₂ each independently represents 0 or 1; d ₃ , d ₄ , d ₅ and d ₆ each independently represent an integer of 0 or more and 5 or less. d ₇ and d ₈ each independently represents an integer of 0 or more and 4 or less.

In general formula (11), the alkyl group having 1 to 8 carbon atoms represented by R ¹¹¹ to R ¹¹⁸ is preferably an alkyl group having 1 to 4 carbon atoms, and is a methyl group or an ethyl group. Is more preferable.

In the general formula (11), when d ₃ represents an integer of 2 or more and 5 or less, the plurality of R ¹¹³ may be the same as or different from each other. When d ₄ represents an integer of 2 or more and 5 or less, the plurality of R ¹¹⁴ may be the same as or different from each other. When d ₅ represents an integer of 2 or more and 5 or less, the plurality of R ¹¹⁵ may be the same as or different from each other. When d ₆ represents an integer of 2 or more and 5 or less, the plurality of R ¹¹⁶ may be the same as or different from each other. When d ₇ represents an integer of 2 or more and 4 or less, the plurality of R ¹¹⁷ may be the same as or different from each other. When d ₈ represents an integer of 2 or more and 4 or less, the plurality of R ¹¹⁸ may be the same as or different from each other.

In general formula (11), R ¹¹¹ and R ¹¹² preferably each independently represent a hydrogen atom or a phenyl group. R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , R ¹¹⁷ and R ¹¹⁸ each independently preferably represents an alkyl having 1 to 8 carbon atoms. d ₁ and d ₂ are the same as each other, and preferably represent 0 or 1. d ₃ and d ₅ each preferably represent 0. d ₄ and d ₆ are the same as each other, and preferably represent 0 or 2. d ₇ and d ₈ each preferably represent 0. In order to improve the filming resistance and wear resistance of the photoreceptor, it is more preferable that d ₁ and d ₂ each represent 1. In order to improve electrical characteristics (especially sensitivity characteristics) and wear resistance of the photoreceptor, R ¹¹¹ and R ¹¹² each preferably represent a hydrogen atom. In order to improve filming resistance, electrical characteristics (especially sensitivity characteristics) and abrasion resistance of the photoreceptor, d ₁ and d ₂ each represent 1, and R ¹¹¹ and R ¹¹² each represent a hydrogen atom. Particularly preferred.

Preferable examples of compound (11) include compounds represented by chemical formula (HTM-5), (HTM-6) or (HTM-7) (hereinafter referred to as compound (HTM-5), (HTM-6) or (It may be described as (HTM-7)).

Compound (12) is represented by the following general formula (12).

In the general formula (12), R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ and R ¹²⁶ are each independently an alkyl group having 1 to 8 carbon atoms, a phenyl group, or 1 to 8 carbon atoms. The following alkoxy groups are represented. e ₁ , e ₂ , e ₄ and e ₅ each independently represents an integer of 0 or more and 5 or less. e ₃ and e ₆ each independently represents an integer of 0 or more and 4 or less.

In general formula (12), the alkyl group having 1 to 8 carbon atoms represented by R ¹²¹ to R ¹²⁶ is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group.

In the general formula (12), when e ₁ represents an integer of 2 or more and 5 or less, the plurality of R ¹²¹ may be the same as or different from each other. When e ₂ represents an integer of 2 or more and 5 or less, the plurality of R ¹²² may be the same as or different from each other. When e ₃ represents an integer of 2 or more and 4 or less, the plurality of R ¹²³ may be the same as or different from each other. When e ₄ represents an integer of 2 or more and 5 or less, the plurality of R ¹²⁴ may be the same as or different from each other. When e ₅ represents an integer of 2 or more and 5 or less, the plurality of R ¹²⁵ may be the same as or different from each other. When e ₆ represents an integer of 2 or more and 4 or less, the plurality of R ¹²⁶ may be the same as or different from each other.

The diphenylaminophenyl ethenyl group having R ¹²⁴ , R ¹²⁵ and R ¹²⁶ is bonded to the ortho, meta or para position of the phenyl group to which the diphenylaminophenyl ethenyl having R ¹²¹ , R ¹²² and R ¹²³ is bonded. .

In the general formula _{(12), e 1, e} 2, e 4 and e ₅ are each independently preferably represents an integer of 0 to 2 or less. _one of e ₁ and e ₂ represents 0 and the other represents 2 and one of e ₄ and e ₅ represents 0 and the other represents 2, or e ₁ , e ₂ , e ₄ and e ₅ are each 1 Is more preferable. It is preferable that e ₃ and e ₆ each represent 0.

In the general formula (12), it is preferable that R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ and R ¹²⁶ each independently represents an alkyl group having 1 to 8 carbon atoms. It is preferable that e ₁ , e ₂ , e ₄ and e ₅ each independently represent an integer of 0 or more and 2 or less. It is preferable that e ₃ and e ₆ each represent 0. In order to improve the filming resistance and wear resistance of the photoreceptor, _one of e ₁ and e ₂ represents 0 and the other represents 2, and one of e ₄ and e ₅ represents 0 and the other is 2 Is more preferable.

Preferable examples of the compound (12) include compounds represented by the chemical formula (HTM-8) or (HTM-9) (hereinafter sometimes referred to as the compound (HTM-8) or (HTM-9)). Is mentioned.

In order to improve electrical characteristics (particularly sensitivity characteristics) in addition to filming resistance and abrasion resistance of the photoreceptor, the compound (10), (11) or (12) is preferable as the hole transport agent. For the same reason, compounds (HTM-1) to (HTM-9) are more preferable as the hole transporting agent.

In order to improve the filming resistance and abrasion resistance of the photoreceptor, the hole transporting agent is preferably the compound (10), (11) or (12), and more preferably the compound (10). In order to improve the filming resistance and abrasion resistance of the photoreceptor, the hole transport agent may be a compound (HTM-1), (HTM-2), (HTM-3), (HTM-5) or (HTM-8) is preferred, and compound (HTM-2) or (HTM-3) is more preferred.

In order to improve the filming resistance and electrical characteristics (especially sensitivity characteristics) of the photoreceptor, the hole transporting agent is preferably compound (10), (11) or (12), and compound (11) is more preferred. preferable. In order to improve the filming resistance and electrical characteristics (especially sensitivity characteristics) of the photoreceptor, the compound (HTM-1), (HTM-2), (HTM-3), (HTM) -4), (HTM-5) or (HTM-6) is preferred, and compound (HTM-5) or (HTM-6) is more preferred.

In order to improve the filming resistance, abrasion resistance and electrical characteristics (especially sensitivity characteristics) of the photoreceptor, holes contained in the photosensitive layer (specifically, charge transport layer or single layer type photosensitive layer) There is only one kind of transport agent, and this one kind of hole transport agent is preferably compound (10), (11) or (12).

In order to further improve the filming resistance, abrasion resistance and electrical characteristics (especially sensitivity characteristics) of the photoreceptor, the positive layer contained in the photosensitive layer (specifically, a charge transport layer or a single-layer type photosensitive layer). It is preferable that the pore transport agent and the binder resin are as follows. There is only one kind of hole transport agent, and this one kind of hole transport agent is the compound (10), (11) or (12). The binder resin is a polyarylate resin (PA) in which the repeating unit (1) is the repeating unit (1-1) and the repeating unit (2) is the repeating unit (2-3).

The photosensitive layer may contain only the compound (10), (11) or (12) as a hole transport agent. Alternatively, the photosensitive layer further contains a hole transport agent other than the compounds (10), (11) and (12) in addition to the compound (10), (11) or (12) as a hole transport agent. May be. When the hole transport agent contains the compound (10), (11) or (12), the content of the compound (10), (11) or (12) is 80 masses with respect to the mass of the hole transport agent. % Or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.

Examples of other hole transporting agents include compounds represented by the following chemical formulas (HTM-10) to (HTM-12) (hereinafter sometimes referred to as compounds (HTM-10) to (HTM-12)). Can be mentioned.

When the photoreceptor is a multilayer photoreceptor, the content of the hole transport agent is preferably 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer. More preferably, it is 20 parts by mass or more and 100 parts by mass or less.

When the photoreceptor is a monolayer type photoreceptor, the content of the hole transport agent contained in the monolayer type photosensitive layer is 10 masses with respect to 100 parts by mass of the binder resin contained in the monolayer type photosensitive layer. It is preferably no less than 200 parts by mass and more preferably no greater than 10 parts by mass and no greater than 100 parts by mass.

(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, squaraine pigments, indigo pigments, azurenium pigments, cyanine Pigments, inorganic photoconductive materials (for example, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide or amorphous silicon) powders, pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, Examples include pyrazoline pigments and quinacridone pigments. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the phthalocyanine pigment include metal-free phthalocyanine or metal phthalocyanine. Examples of the metal phthalocyanine include titanyl phthalocyanine, hydroxygallium phthalocyanine, or 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 non-crystalline. The crystal shape of the phthalocyanine pigment (for example, α type, β type, Y type, V type or II type) is not particularly limited, and phthalocyanine pigments having various crystal shapes are used.

Examples of the crystal of metal-free phthalocyanine include a metal-free phthalocyanine X-type crystal (hereinafter sometimes referred to as X-type metal-free phthalocyanine). Examples of the crystal of titanyl phthalocyanine include α-type, β-type, and Y-type crystals of titanyl phthalocyanine (hereinafter sometimes referred to as α-type, β-type, or Y-type titanyl phthalocyanine). Examples of the crystal of hydroxygallium phthalocyanine include a V-type crystal of hydroxygallium 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 photoreceptor having sensitivity in a wavelength region of 700 nm or more. Since it has a high quantum yield in a wavelength region of 700 nm or more, the charge generator is preferably a phthalocyanine pigment, more preferably a metal-free phthalocyanine or titanyl phthalocyanine, and even more preferably an X-type metal-free phthalocyanine or a Y-type titanyl phthalocyanine. Y-type titanyl phthalocyanine is particularly preferred.

An santhrone pigment is preferably used as a charge generating agent in a photoreceptor applied to an image forming apparatus using a short wavelength laser light source (for example, a laser light source having a wavelength of 350 nm to 550 nm).

The content of the charge generating agent is preferably 0.1 parts by weight or more and 50 parts by weight or less, and 0.5 parts by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the binder resin contained in the photosensitive layer. More preferably, it is more preferably 0.5 parts by mass or more and 4.5 parts by mass or less.

(Electron transfer agent and electron acceptor compound)
When the photoreceptor is a multilayer photoreceptor, the charge transport layer may contain an electron acceptor compound. When the photoreceptor is a single layer type photoreceptor, the single layer type photosensitive layer may contain an electron transport agent.

Examples of electron transport agents and electron acceptor compounds include quinone compounds, diimide compounds, hydrazone compounds, thiopyran compounds, trinitrothioxanthone compounds, 3,4,5,7-tetranitro-9-fluorenone compounds, Examples thereof include dinitroanthracene compounds, dinitroacridine compounds, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroacridine, succinic anhydride, maleic anhydride or dibromomaleic anhydride. Examples of quinone compounds include diphenoquinone compounds (eg, 3,3 ′, 5,5′-tetra-tert-butyl-4,4′-diphenoquinone), azoquinone compounds, anthraquinone compounds, naphthoquinone compounds, Examples thereof include nitroanthraquinone compounds and dinitroanthraquinone compounds. An electron transfer agent may be used individually by 1 type, and may be used in combination of 2 or more type. An electron acceptor compound may be used individually by 1 type, and may be used in combination of 2 or more type.

When the photoreceptor is a single layer type photoreceptor, the content of the electron transport agent contained in the single layer type photosensitive layer is 5 parts by mass with respect to 100 parts by mass of the binder resin contained in the single layer type photosensitive layer. The amount is preferably 100 parts by mass or less and more preferably 10 parts by mass or more and 80 parts by mass or less.

When the photoreceptor is a multilayer photoreceptor, the content of the electron acceptor compound contained in the charge transport layer is 0.1 parts by mass or more and 20 parts by mass with respect to 100 parts by mass of the binder resin contained in the charge transport layer. Part or less.

(Combination of materials)
It is preferable that the hole transport agent and the binder resin are any one of the following combinations. It is preferable that the hole transporting agent and the binder resin are any of the following combinations, and the charge generating agent is Y-type titanyl phthalocyanine. It is preferable that the hole transport agent and the binder resin are any of the following combinations, and the electron acceptor compound is 3,3 ′, 5,5′-tetra-tert-butyl-4,4′-diphenoquinone. The hole transport agent and the binder resin are any of the following combinations, the charge generator is Y-type titanyl phthalocyanine, and the electron acceptor compound is 3,3 ′, 5,5′-tetra-tert-butyl-4 4,4′-diphenoquinone is preferred.

The binder resin is a polyarylate resin containing a repeating unit (1-1) and a repeating unit (2-3), and the hole transporting agent is a compound (HTM-1), (HTM-2), (HTM-3) , (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) and (HTM-9);
The binder resin is a polyarylate resin containing a repeating unit (1-1) and a repeating unit (2-1), and the hole transporting agent is a compound (HTM-1), (HTM-2), (HTM-3) , (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) and (HTM-9);
The binder resin is a polyarylate resin containing a repeating unit (1-1) and a repeating unit (2-2), and the hole transporting agent is a compound (HTM-1), (HTM-2), (HTM-3) , (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) and (HTM-9); or the binder resin is a repeating unit ( 1-2) and a polyarylate resin containing the repeating unit (2-4), and the hole transport agent is compound (HTM-1), (HTM-2), (HTM-3), (HTM-4) , (HTM-5), (HTM-6), (HTM-7), (HTM-8) and (HTM-9).

More preferably, the hole transporting agent and the binder resin are any of the following combinations. More preferably, the hole transporting agent and the binder resin are any of the following combinations, and the charge generating agent is Y-type titanyl phthalocyanine. More preferably, the hole transporting agent and the binder resin are any of the following combinations, and the electron acceptor compound is 3,3 ′, 5,5′-tetra-tert-butyl-4,4′-diphenoquinone. . The hole transport agent and the binder resin are any of the following combinations, the charge generator is Y-type titanyl phthalocyanine, and the electron acceptor compound is 3,3 ′, 5,5′-tetra-tert-butyl-4 More preferably, 4'-diphenoquinone. The polyarylate resins (PA-1) to (PA-6) will be described later in Examples.

The binder resin is polyarylate resin (PA-1), and the hole transport agent is compound (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) or (HTM-9);
The binder resin is polyarylate resin (PA-2), and the hole transport agent is compound (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) or (HTM-9);
The binder resin is polyarylate resin (PA-3), and the hole transport agent is compound (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) or (HTM-9);
The binder resin is polyarylate resin (PA-4), and the hole transport agent is compound (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) or (HTM-9);
The binder resin is polyarylate resin (PA-5), and the hole transport agent is compound (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) and (HTM-9); or the binder resin is a polyarylate resin (PA-6) and the hole transport agent is Compounds (HTM-1), (HTM-2), (HTM-3), (HTM-4), (HTM-5), (HTM-6), (HTM-7), (HTM-8) and ( HTM-9).

The preferred combination of the hole transport agent and the binder resin has been described above.

(Additive)
Examples of additives include deterioration inhibitors (for example, antioxidants, radical scavengers, singlet quenchers or ultraviolet absorbers), softeners, surface modifiers, extenders, thickeners, dispersion stabilizers. , Waxes, acceptors, donors, surfactants, plasticizers, sensitizers or leveling agents. Antioxidants include, for example, hindered phenols (eg, di (tert-butyl) p-cresol), hindered amines, paraphenylenediamine, arylalkanes, hydroquinones, spirochromans, spirodinones or their derivatives, organic sulfur compounds or An organic phosphorus compound is mentioned.

<Conductive substrate>
The conductive substrate is not particularly limited as long as it can be used as the conductive substrate of the photoreceptor. The conductive substrate may be formed of a material having at least a surface portion having conductivity. An example of the conductive substrate is a conductive substrate formed of a conductive material. Another example of the 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. These conductive materials may be used alone or in combination of two or more (for example, as an alloy). Among these materials having conductivity, aluminum or an aluminum alloy is preferable because charge transfer 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 or a drum shape. The thickness of the conductive substrate is appropriately selected according to the shape of the conductive substrate.

<Intermediate layer>
The intermediate layer (undercoat layer) contains, for example, inorganic particles and a resin (intermediate layer resin) used for the intermediate layer. The presence of the intermediate layer is considered to suppress the increase in resistance by smoothing the flow of current generated when the photosensitive member is exposed while maintaining an insulating state capable of suppressing the occurrence of leakage.

Examples of the inorganic particles include metal (for example, aluminum, iron or copper), metal oxide (for example, titanium oxide, alumina, zirconium oxide, tin oxide or zinc oxide) particles or non-metal oxide (for example, silica). Particles. These inorganic particles may be used individually by 1 type, and may use 2 or more types together.

The intermediate layer resin is not particularly limited as long as it can be used as a resin for forming the intermediate layer. The intermediate layer may contain an additive. Examples of the additive are the same as those of the photosensitive layer.

<Method for producing photoconductor>
As a method for producing a photoreceptor, an example of a method for producing a laminated photoreceptor and an example of a method for producing a single layer photoreceptor will be described.

(Manufacturing method of laminated photoreceptor)
In the method for producing a multilayer photoreceptor, the photosensitive layer forming step includes 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, sometimes referred to as a charge generation layer coating liquid) is prepared. A charge generation layer coating solution is applied onto the conductive substrate. Next, at least a part of the solvent contained in the applied charge generation layer coating solution is removed to form a charge generation layer. The charge generation layer coating solution includes, for example, a charge generation agent, a base resin, and a solvent. Such a charge generation layer coating solution is prepared by dissolving or dispersing a charge generation agent and a base resin in a solvent. An additive may be added to the charge generation layer coating solution as necessary.

In the charge transport layer forming step, first, a coating liquid for forming the charge transport layer (hereinafter, sometimes referred to as a charge transport layer coating liquid) is prepared. A charge transport layer coating solution is applied onto the charge generation layer. Next, at least a part of the solvent contained in the applied charge transport layer coating solution is removed to form a charge transport layer. The coating solution for charge transport layer contains a hole transport agent, a polyarylate resin (PA) as a binder resin, and a solvent. The charge transport layer coating solution can be prepared by dissolving or dispersing a hole transport agent and a polyarylate resin (PA) in a solvent. If necessary, one or more electron acceptor compounds and additives may be added to the charge transport layer coating solution.

(Method for producing single-layer type photoreceptor)
In the method for producing a single layer type photoreceptor, in the photosensitive layer forming step, a coating solution for forming a single layer type photosensitive layer (hereinafter sometimes referred to as a coating solution for a single layer type photosensitive layer) is prepared. A single layer type photosensitive layer coating solution is coated on a conductive substrate. Next, at least a part of the solvent contained in the applied photosensitive layer coating solution is removed to form a single-layer type photosensitive layer. The single-layer photosensitive layer coating solution contains, for example, a charge generator, a hole transport agent, a polyarylate resin (PA) as a binder resin, and a solvent. Such a single-layer photosensitive layer coating solution is prepared by dissolving or dispersing a charge generating agent, a hole transporting agent, and a polyarylate resin (PA) as a binder resin in a solvent. One or more of an electron transport agent and an additive may be added to the coating solution for the photosensitive layer as necessary.

The solvent contained in the coating solution for charge generation layer, the coating solution for charge transport layer, and the coating solution for single-layer type photosensitive layer (hereinafter sometimes referred to as coating solution) dissolves each component contained in the coating solution. Or if it can disperse | distribute, it will not specifically limit. Examples of the solvent include alcohol (more specifically, methanol, ethanol, isopropanol, butanol, etc.), aliphatic hydrocarbon (more specifically, n-hexane, octane, cyclohexane, etc.), aromatic carbonization, and the like. Hydrogen (more specifically, benzene, toluene, xylene, etc.), halogenated hydrocarbon (more specifically, dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, etc.), ether (more specifically, dimethyl ether) , Diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, or diethylene glycol dimethyl ether), ketones (more specifically, acetone, methyl ethyl ketone, or cyclohexanone), esters (more specifically, ethyl acetate or methyl acetate, etc.), Methyl formaldehyde, dimethylformamide, or dimethyl sulfoxide. These solvents may be used alone or in combination of two or more. Of these solvents, non-halogen solvents (solvents other than halogenated hydrocarbons) are preferably used.

The solvent contained in the charge transport layer coating solution is preferably different from the solvent contained in the charge generation layer coating solution. This is because when the charge transport layer coating solution is applied onto the charge generation layer, it is preferable that the charge generation layer does not dissolve in the solvent of the charge transport layer coating solution.

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

In order to improve the dispersibility of each component or the surface smoothness of each layer formed, the coating liquid may contain, for example, a surfactant or a leveling agent.

The method for applying the coating solution is not particularly limited as long as it is a method capable of uniformly applying the coating solution. Examples of the coating method include a dip coating method, a spray coating method, a spin coating method, and a bar coating method.

The method for removing at least a part of the solvent contained in the coating solution is not particularly limited as long as it is a method capable of evaporating the solvent in the coating solution. Examples of the removal method include heating, reduced pressure, or combined use of heating and reduced pressure. More specifically, a method of performing heat treatment (hot air drying) using a high-temperature dryer or a vacuum dryer can be mentioned. The heat treatment conditions are, for example, a temperature of 40 ° C. or higher and 150 ° C. or lower and a time of 3 minutes or longer and 120 minutes or shorter.

Note that the method for manufacturing a photoreceptor may further include a step of forming an intermediate layer as necessary. A known method can be selected as appropriate for the step of forming the intermediate layer.

Hereinafter, the present invention will be described more specifically using examples. However, the present invention is not limited to the scope of the examples.

The following charge generating agents were prepared as materials for forming the charge generating layer of the photoreceptor. In addition, the following hole transport agent and binder resin were prepared as materials for forming the charge transport layer of the photoreceptor.

(Charge generator)
A Y-type titanyl phthalocyanine represented by the chemical formula (CGM-2) described in the embodiment was prepared as a charge generating agent.

(Hole transport agent)
The compounds (HTM-1) to (HTM-12) described in the embodiment were prepared as hole transport agents.

(Binder resin)
Polyarylate resins (PA-1) to (PA-4) were produced as binder resins.

[Preparation of polyarylate resin (PA-1)]
The following polyarylate resin (PA-1) was prepared. The polyarylate resin (PA-1) contained only the repeating unit (1-1) and the repeating unit (2-3) as repeating units. The ratio n ₁ / (n ₁ + n ₂ ) of the polyarylate resin (PA-1) was 0.50. The ratio n ₂ / (n ₁ + n ₂ ) of the polyarylate resin (PA-1) was 0.50.

In preparing the polyarylate resin (PA-1), a 2 L three-necked flask equipped with a thermometer and a three-way cock was used as a reaction vessel. In a reaction vessel, 20.01 g (82.56 mmol) of 1,1-bis (4-hydroxy-3-methylphenyl) ethane (compound (BP-1) described in the embodiment), 0.124 g of tert-butylphenol ( 0.826 mmol), 7.84 g (196 mmol) of sodium hydroxide and 0.240 g (0.768 mmol) of benzyltributylammonium chloride. The air in the reaction vessel was replaced with argon gas. 600 mL of water was added to the contents of the reaction vessel. The contents of the reaction vessel were stirred at 20 ° C. for 1 hour. Next, the content of the reaction vessel was cooled until the temperature of the content of the reaction vessel reached 10 ° C. to obtain an alkaline aqueous solution A.

Meanwhile, 9.84 g (38.9 mmol) of 2,6-naphthalenedicarboxylic acid dichloride (dichloride of the compound (DC-1-1) described in the embodiment) and 4,4′-oxybisbenzoic acid dichloride (embodiment) 11.47 g (38.9 mmol) of the compound (DC-5) dichloride described in 1) was dissolved in 300 g of chloroform (amylene-added product). Thereby, chloroform solution B was obtained.

While the alkaline aqueous solution A in the reaction vessel was stirred at 10 ° C., the chloroform solution B was added to the alkaline aqueous solution A. This initiated a polymerization reaction. While adjusting the temperature (liquid temperature) of the contents of the reaction vessel to 13 ± 3 ° C., the contents of the reaction vessel were stirred for 3 hours to proceed the polymerization reaction. Subsequently, the upper layer (water layer) in the contents of the reaction vessel was removed using a decant to obtain an organic layer. Next, 500 mL of ion-exchanged water was put into a 2 L Erlenmeyer flask. The resulting organic layer was added to the flask contents. To the flask contents, 300 g of chloroform and 6 mL of acetic acid were further added. The flask contents were then stirred at room temperature for 30 minutes. Thereafter, the upper layer (aqueous layer) in the flask contents was removed using a decant to obtain an organic layer. The obtained organic layer was washed with 500 mL of ion exchange water using a separatory funnel. Washing with ion-exchanged water was repeated 8 times. As a result, an organic layer washed with water was obtained.

Next, the organic layer washed with water was filtered to obtain a filtrate. 1.5 L of methanol was placed in a 3 L beaker. The obtained filtrate was slowly added dropwise to methanol in a beaker to obtain a precipitate. The precipitate was removed by filtration. The taken out precipitate was vacuum-dried at a temperature of 70 ° C. for 12 hours. As a result, a polyarylate resin (PA-1) was obtained. The yield of polyarylate resin (PA-1) was 30.0 g, and the yield was 87.0 mol%. The resulting polyarylate resin (PA-1) had a viscosity average molecular weight of 55,400.

[Preparation of polyarylate resin (PA-2)]
The following polyarylate resin (PA-2) was prepared. The polyarylate resin (PA-2) contained only the repeating unit (1-1) and the repeating unit (2-1) as repeating units. The ratio n ₁ / (n ₁ + n ₂ ) of the polyarylate resin (PA- ₂ ) was 0.50. The ratio n ₂ / (n ₁ + n ₂ ) of the polyarylate resin (PA- ₂ ) was 0.50.

Specifically, a polyarylate resin (PA-2) was produced in the same manner as the production of the polyarylate resin (PA-1) except that the following points were changed. 11.47 g (38.9 mmol) of 4,4′-oxybisbenzoic acid dichloride (dichloride of compound (DC-5) described in the embodiment) was converted into dichloride 38. of compound (DC-2) described in the embodiment. Changed to 9 mmol. The resulting polyarylate resin (PA-2) had a viscosity average molecular weight of 57,000.

[Preparation of polyarylate resin (PA-3)]
The following polyarylate resin (PA-3) was prepared. The polyarylate resin (PA-3) contained only the repeating unit (1-1) and the repeating unit (2-2) as repeating units. The ratio n ₁ / (n ₁ + n ₂ ) of the polyarylate resin (PA-3) was 0.50. The ratio n ₂ / (n ₁ + n ₂ ) of the polyarylate resin (PA-3) was 0.50.

Specifically, a polyarylate resin (PA-3) was produced in the same manner as the production of the polyarylate resin (PA-1) except that the following points were changed. 11.47 g (38.9 mmol) of 4,4′-oxybisbenzoic acid dichloride (dichloride of the compound (DC-5) described in the embodiment) was converted into dichloride 38. of the compound (DC-3) described in the embodiment. Changed to 9 mmol. The resulting polyarylate resin (PA-3) had a viscosity average molecular weight of 50,600.

[Preparation of polyarylate resin (PA-4)]
The following polyarylate resin (PA-4) was prepared. The polyarylate resin (PA-4) contained only the repeating unit (1-2) and the repeating unit (2-4) as repeating units. The ratio n ₁ / (n ₁ + n ₂ ) of the polyarylate resin (PA-4) was 0.50. The ratio n ₂ / (n ₁ + n ₂ ) of the polyarylate resin (PA-4) was 0.50.

Specifically, a polyarylate resin (PA-4) was produced in the same manner as the production of the polyarylate resin (PA-1) except that the following points were changed. 20.01 g (82.56 mmol) of 1,1-bis (4-hydroxy-3-methylphenyl) ethane (compound (BP-1) described in the embodiment) was added to the compound (BP-2 described in the embodiment). ) 82.56 mmol. The resulting polyarylate resin (PA-4) had a viscosity average molecular weight of 57,000.

[Preparation of polyarylate resin (PA-5)]
The following polyarylate resin (PA-5) was prepared. The polyarylate resin (PA-5) contained only the repeating unit (1-1) and the repeating unit (2-3) as repeating units. The ratio n ₁ / (n ₁ + n ₂ ) of the polyarylate resin (PA-5) was 0.30. The ratio n ₂ / (n ₁ + n ₂ ) of the polyarylate resin (PA-5) was 0.70.

Specifically, a polyarylate resin (PA-5) was produced in the same manner as the production of the polyarylate resin (PA-1) except that the following points were changed. The addition amount of 2,6-naphthalenedicarboxylic acid dichloride (dichloride of the compound (DC-1-1) described in the embodiment) was changed from 9.84 g (38.9 mmol) to 23.3 mmol. In addition, the amount of 4,4'-oxybisbenzoic acid dichloride (the dichloride of the compound (DC-5) described in the embodiment) was changed from 11.47 g (38.9 mmol) to 54.5 mmol. The resulting polyarylate resin (PA-5) had a viscosity average molecular weight of 50,100.

[Preparation of polyarylate resin (PA-6)]
The following polyarylate resin (PA-6) was prepared. The polyarylate resin (PA-6) contained only the repeating unit (1-1) and the repeating unit (2-3) as the repeating unit. The ratio n ₁ / (n ₁ + n ₂ ) of the polyarylate resin (PA-6) was 0.70. The ratio n ₂ / (n ₁ + n ₂ ) of the polyarylate resin (PA-6) was 0.30.

Specifically, a polyarylate resin (PA-6) was produced in the same manner as the production of the polyarylate resin (PA-1) except that the following points were changed. The addition amount of 2,6-naphthalenedicarboxylic acid dichloride (dichloride of the compound (DC-1-1) described in the embodiment) was changed from 9.84 g (38.9 mmol) to 54.5 mmol. The amount of 4,4'-oxybisbenzoic acid dichloride (dichloride of the compound (DC-6) described in the embodiment) added was changed from 11.47 g (38.9 mmol) to 23.3 mmol. The resulting polyarylate resin (PA-6) had a viscosity average molecular weight of 50,800.

Next, ¹ H-NMR spectra of each of the prepared polyarylate resins (PA-1) to (PA-6) were measured using a proton nuclear magnetic resonance spectrometer (manufactured by JASCO Corporation, 300 MHz). CDCl ₃ was used as the solvent. Tetramethylsilane (TMS) was used as an internal standard sample. Of these, polyarylate resin (PA-1) is given as a representative example.

FIG. 3 shows the ¹ H-NMR spectrum of polyarylate resin (PA-1). FIG. 4 shows an enlarged view of the range from 6.90 ppm to 9.00 ppm of the ¹ H-NMR spectrum shown in FIG. FIG. 5 shows an enlarged view of the range of 1.2 ppm to 4.5 ppm of the ¹ H-NMR spectrum shown in FIG. 3 to 5, the horizontal axis indicates the chemical shift (unit: ppm), and the vertical axis indicates the signal intensity (unit: arbitrary unit). ^{From 1} H-NMR spectrum, it was confirmed that polyarylate resin (PA-1) was obtained. As for the polyarylate resins (PA-2) to (PA-6), it was confirmed from the ¹ H-NMR spectrum that the polyarylate resins (PA-2) to (PA-6) were obtained, respectively.

As the binder resin, polyarylate resins represented by chemical formulas (PA-a) to (PA-f) (hereinafter sometimes referred to as polyarylate resins (PA-a) to (PA-f)) were also prepared. . The subscripts attached to the repeating units in the chemical formulas (PA-a) to (PA-f) indicate the ratio of the number of repeating units to which the subscripts are added to the total number of repeating units contained in the resin. .

The polyarylate resin (PA-a) had only a repeating unit represented by the following chemical formula (PA-a). The viscosity average molecular weight of (PA-a) was 60,300.

The polyarylate resin (PA-b) had two types of repeating units represented by the following chemical formula (PA-b). The viscosity average molecular weight of (PA-b) was 45,600.

The polyarylate resin (PA-c) had two types of repeating units represented by the following chemical formula (PA-c). The viscosity average molecular weight of (PA-c) was 45,600.

The polyarylate resin (PA-d) had two types of repeating units represented by the following chemical formula (PA-d). The viscosity average molecular weight of (PA-d) was 47,800.

The polyarylate resin (PA-e) had two types of repeating units represented by the following chemical formula (PA-e). The viscosity average molecular weight of (PA-e) was 58,000.

The polyarylate resin (PA-f) had two types of repeating units represented by the following chemical formula (PA-f). The viscosity average molecular weight of (PA-f) was 59,500.

<Manufacture of photoconductor>
Photoconductors (A-1) to (A-16) and (B-1) to (B-6) were produced using the charge generating agent, hole transporting agent and binder resin described above.

(Manufacture of photoconductor (A-1))
An intermediate layer was formed. First, surface-treated titanium oxide (“Prototype SMT-A” manufactured by Teika Co., Ltd., average primary particle size 10 nm) was prepared. Specifically, 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, surface-treated titanium oxide (2 parts by mass) and a polyamide resin (quaternary polyamide resin of “Amilan (registered trademark) CM8000”, polyamide 6, polyamide 12, polyamide 66 and polyamide 610 manufactured by Toray Industries, Inc.) (1 part by mass) was added to a solvent containing methanol (10 parts by mass), butanol (1 part by mass) and toluene (1 part by mass). Using a bead mill, these materials and the solvent were mixed for 5 hours to disperse the materials in the solvent. This prepared the coating liquid for intermediate | middle layers. The obtained intermediate layer coating solution was filtered using a filter having an opening of 5 μm. Then, the intermediate layer coating solution was applied to the surface of the conductive substrate using a dip coating method. As the conductive substrate, an aluminum drum-shaped support (diameter 30 mm, total length 246 mm) was used. Subsequently, the applied intermediate layer coating solution was dried at 130 ° C. for 30 minutes to form an intermediate layer (film thickness: 1.5 μm) on the conductive substrate.

Next, a charge generation layer was formed. Specifically, a Y-type titanyl phthalocyanine (1.5 parts by mass) and a polyvinyl acetal resin (“SREC BX-5” manufactured by Sekisui Chemical Co., Ltd.) (1 part by mass) as a base resin were mixed with propylene glycol monomethyl ether ( 40 parts by mass) and a solvent containing tetrahydrofuran (40 parts by mass). Using a bead mill, these materials and the solvent were mixed for 12 hours, and the materials were dispersed in the solvent to prepare a charge generation layer coating solution. The obtained coating solution for charge generation layer was filtered using a filter having an opening of 3 μm. Next, the obtained filtrate was applied on the intermediate layer using a dip coating method and dried at 50 ° C. for 5 minutes. As a result, a charge generation layer (thickness: 0.3 μm) was formed on the intermediate layer.

Next, a charge transport layer was formed. Specifically, 50 parts by mass of the compound (HTM-1) as a hole transport agent and 2 parts by mass of a hindered phenol antioxidant (“Irganox (registered trademark) 1010” manufactured by BASF Corporation) as an additive, 2,3 parts by weight of 3,3 ′, 5,5′-tetra-tert-butyl-4,4′-diphenoquinone as an electron acceptor compound and 100 parts by weight of a polyarylate resin (PA-1) as a binder resin, It added with respect to the solvent containing 550 mass parts of tetrahydrofuran and 150 mass parts of toluene. These were mixed and the material was dispersed in a solvent to prepare a coating solution for a charge transport layer. The obtained coating solution for charge transport layer was applied onto the charge generation layer using a dip coating method and dried at 120 ° C. for 40 minutes. Thereby, a charge transport layer (film thickness 20 μm) was formed on the charge generation layer. As a result, a photoreceptor (A-1) was obtained. The photoreceptor (A-1) was a multilayer photoreceptor. In the photoreceptor (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.

(Production of photoconductors (A-2) to (A-16) and (B-1) to (B-6))
Photoconductors (A-2) to (A-16) and (B-1) to (B-1) are prepared in the same manner as the production of photoconductor (A-1) except that the following points (1) to (3) are changed. Each of (B-6) was produced.
(1) In the production of the photoreceptor (A-1), polyarylate resin (PA-1) was used as the binder resin, but the photoreceptors (A-2) to (A-16) and (B-1) to In each production of (B-6), binder resins of the types shown in Tables 1 and 2 were used.
(2) In the production of the photoreceptor (A-1), the compound (HTM-1) was used as the hole transport agent, but the photoreceptors (A-2) to (A-15) and (B-1) to In each production of (B-6), hole transport agents of the types shown in Table 1 and Table 2 were used.
(3) In the production of the photoreceptor (A-1), 50 parts by mass of the compound (HTM-1) was used as a hole transport agent. However, in the production of the photoreceptor (A-16), the compound (HTM-11) was used. 25 parts by mass and 25 parts by mass of the compound (HTM-12) were used.

<Evaluation>
First, the filming resistance of the photoreceptor was examined by changing the type of the binder resin.

<Evaluation of filming resistance>
Filming resistance was evaluated for each of the photoreceptors (A-1) to (A-6) and the photoreceptors (B-1) to (B-6). As evaluation of filming resistance, the following image evaluation and filming rate were evaluated.

(Image evaluation)
The photoconductor was mounted on an evaluation machine. The evaluation machine was a color printer (“C711dn” manufactured by Oki Data Corporation). The toner cartridge of the evaluator was filled with cyan toner. Under a high temperature and high humidity environment (temperature 32 ° C. and relative humidity 85% RH: hereinafter sometimes referred to as HH environment), printing was performed on 2,000 sheets at intervals of 16 seconds using an evaluation machine. Next, printing was performed on 2,000 sheets at intervals of 16 seconds using an evaluation machine under a low-temperature and low-humidity environment (temperature: 10 ° C. and relative humidity: 15% RH: hereinafter sometimes referred to as LL environment). After printing on 2,000 sheets in the LL environment, the evaluation machine was allowed to stand for 2 hours. Next, one solid image (image density 100%) was printed in an LL environment. The solid image was used as the evaluation image. The evaluation image was visually observed to confirm whether the image was missing. Images were evaluated according to the following criteria. Table 1 shows the results of the image evaluation. In addition, when filming occurs on the surface of the photoconductor, there is a tendency that a chip appears in the image.

(Evaluation criteria)
Good: No missing image was confirmed.
Defect: A missing image was confirmed.

(Evaluation of filming rate)
After the evaluation image was printed in the image evaluation described above, the photoconductor was taken out of the evaluation machine, and the degree of toner filming on the surface of the photoconductor was observed. Specifically, the surface of the photoreceptor was observed using an optical microscope (“Sennar KK” manufactured by Nikon Corporation) to obtain an observation image. The field of view of the optical microscope was 1.7 mm × 2.1 mm square, and the observation magnification was 50 times. There were three observation points on the surface of the photoconductor (specifically, a region 25 mm from the upper end of the photoconductor, a region at the center, and a region 25 mm from the lower end).

Binary processing was performed on the observation image of the optical microscope. Specifically, using an image analysis software (Image J), a binarization process was performed on the observed image using the luminance value 180 as a threshold value. The pixels constituting the observation image each had a luminance value of 0 or more and 255 or less. A pixel having a luminance value less than the threshold corresponds to a region where filming has occurred. On the other hand, a pixel having a luminance value equal to or higher than the threshold corresponds to a region where filming has not occurred.

The binarized image was subjected to image analysis, and the ratio of the area of the adhered material to the entire image was calculated. Specifically, the area (At) of the region where filming occurred due to the binarization process and the area (An) of the region where filming did not occur were obtained. From the obtained At and An, the area ratio (A) of the region where filming occurred was obtained according to the following calculation formula.
Area ratio A [%] = [At / (At + An)] × 100

The area ratio A was determined for each of the three observation images on the photoreceptor. The number average value of the area ratio A was determined by dividing the sum of the three area ratios A by 3. The number average value of the area ratio A was defined as the filming rate. The filming rate obtained is shown in Table 1. Note that a lower filming rate indicates that filming is less likely to occur on the surface of the photoreceptor.

In Table 1, HTM and molecular weight indicate a hole transport agent and a viscosity average molecular weight, respectively.

Next, in addition to the type of binder resin, the type of hole transporting agent was changed, and the electrical characteristics and abrasion resistance of the photoreceptor were also examined.

<Evaluation of electrical characteristics>
The electrical characteristics of each of the photoreceptors (A-1) to (A-16) and the photoreceptors (B-1) to (B-6) were evaluated. As the evaluation of electrical characteristics, charging characteristics and sensitivity characteristics were evaluated. As the evaluation of the charging characteristics, the following charging potential was evaluated. As the evaluation of the sensitivity characteristics, the following sensitivity potential (hereinafter referred to as post-exposure potential) was evaluated. The evaluation environment of electrical characteristics was a temperature of 23 ° C. and a relative humidity of 50% RH.

(Evaluation of charging potential V ₀ )
Using a drum sensitivity tester (Gentec Co., Ltd.), the photosensitive member was charged under the conditions of a rotational speed of the photosensitive member of 31 rpm and a current flowing into the photosensitive member of −10 μA. The surface potential of the charged photoreceptor was measured. The measured surface potential was defined as the charging potential (V ₀ , unit: −V) of the photoreceptor. Table 2 shows the measured charging potential (V ₀ ) of the photoreceptor.

(Evaluation of post-exposure potential _VL )
Using a drum sensitivity tester (Gentec Co., Ltd.), the surface of the photoreceptor was charged to −600V. Next, monochromatic light (wavelength: 780 nm, exposure amount: 0.8 μJ / cm ² ) was taken out from the light of the halogen lamp using a bandpass filter and irradiated on the surface of the photoreceptor. The surface potential of the photoreceptor was measured when 80 milliseconds had elapsed from the end of monochromatic light irradiation. The measured surface potential was defined as the post-exposure potential (V _L , unit: −V) of the photoreceptor. Table 2 shows the measured post-exposure potential (V _L ) of the photoreceptor.

<Evaluation of wear resistance>
The wear resistance of each of the charge transport layers of the photoreceptors (A-1) to (A-16) and the photoreceptors (B-1) to (B-6) was evaluated. First, the charge transport layer coating solution prepared in the production of the photoreceptor was applied to a polypropylene sheet (thickness 0.3 mm) wound around an aluminum pipe (diameter 78 mm). The polypropylene sheet coated with the charge transport layer coating solution was dried at 120 ° C. for 40 minutes. Thereby, a charge transport layer (evaluation sheet) having a thickness of 20 μm was formed on the polypropylene sheet. Subsequently, the evaluation sheet was peeled from the polypropylene sheet. Then, the peeled evaluation sheet was attached to a wheel (“S-36” manufactured by Taber) to obtain a test piece. The mass of the obtained test piece (the mass of the test piece before the wear test) M1 was measured.

Next, a wear test was performed on the test piece. Specifically, the test piece was attached to a rotary table of a rotary abrasion tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.). Then, with the wear wheel (“CS-10” manufactured by Taber Co., Ltd.) having a load of 500 gf placed on the test piece, the turntable was rotated at a rotation speed of 60 rpm, and a 1000-turn wear test was performed. Subsequently, the mass M2 of the test piece after the wear test was measured. The wear loss (M1-M2), which is the change in the mass of the test piece before and after the test, was determined. Table 2 shows the obtained wear loss.

In Table 2, HTM, molecular weight, V ₀ and V _L represent the hole transport agent, viscosity average molecular weight, charging potential and post-exposure potential, respectively.

The filming resistance evaluation results shown in Table 1 showed the following. The photosensitive layers of the photoreceptors (A-1) to (A-6) are polyarylate containing, as a binder resin, a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2). Contains resin. Specifically, the photosensitive layers of the photoreceptors (A-1) to (A-6) contained any of polyarylate resins (PA-1) to (PA-6) as binder resins. Therefore, as is clear from Table 1, the photoreceptors (A-1) to (A-6) had good image evaluation, a low filming rate, and excellent filming resistance.

On the other hand, the photosensitive layers of the photoreceptors (B-1) to (B-6) include a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2) as a binder resin. It did not contain polyarylate resin. Specifically, the photosensitive layers of the photoconductors (B-1) to (B-6) contained any of polyarylate resins (PA-a) to (PA-f) as binder resins. Polyarylate resins (PA-a) to (PA-f) were not polyarylate resins containing a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2). Therefore, as is apparent from Table 1, the photoreceptors (B-1) to (B-6) had poor image evaluation, high filming rate, and poor filming resistance.

Moreover, the following was shown from the evaluation result of abrasion resistance shown in Table 2. The photosensitive layers of the photoconductors (A-1) to (A-3) and (A-5) to (A-16) are used as a binder resin as a repeating unit represented by the general formula (1) and the general formula (2). And a polyarylate resin containing a repeating unit represented by: Further, R ¹ in the general formulas (1) and (2) represents a methyl group. Therefore, as is apparent from Table 2, the photoreceptors (A-1) to (A-3) and (A-5) to (A-16) have a small wear loss and are resistant to filming. Excellent wear resistance.

Further, the evaluation results of the electrical characteristics (particularly sensitivity characteristics) shown in Table 2 showed the following. The photosensitive layers of the photoreceptors (A-1) to (A-14) are polyarylate containing a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2) as a binder resin. Contains resin. Further, the photosensitive layers of the photoreceptors (A-1) to (A-14) contained the compound (10), (11) or (12) as a hole transport agent. Therefore, as is apparent from Table 2, in the photoreceptors (A-1) to (A-14), the absolute value of the post-exposure potential (V _L ) is small, the filming resistance is improved, and the sensitivity characteristics are improved. It was particularly improved. In the photoreceptors (A-1) to (A-3) and (A-5) to (A-14), the film resistance and the wear resistance were improved, and the sensitivity characteristics were particularly improved. .

From the above, it was shown that the polyarylate resin according to the present invention can suppress the occurrence of filming of the photoreceptor when it is contained in the photosensitive layer. Further, it has been shown that the photoreceptor according to the present invention can suppress the occurrence of filming.

The polyarylate resin according to the present invention can be used for a photoreceptor. The photoreceptor according to the present invention can be used in an image forming apparatus.

Claims

A polyarylate resin comprising a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2).

(In the general formulas (1) and (2), R 1 represents a hydrogen atom or a methyl group,
In the general formula (2), X represents a divalent group represented by the chemical formula (2A), (2B), (2C) or (2D). )
The polyarylate resin according to claim 1 , wherein R 1 in the general formulas (1) and (2) represents a methyl group.
The repeating unit represented by the general formula (1) is a repeating unit represented by the chemical formula (1-1),
The polyarylate resin according to claim 1, wherein the repeating unit represented by the general formula (2) is a repeating unit represented by the chemical formula (2-1), (2-2), or (2-3). .
The repeating unit represented by the general formula (1) is a repeating unit represented by the chemical formula (1-1),
The polyarylate resin according to claim 1, wherein the repeating unit represented by the general formula (2) is a repeating unit represented by the chemical formula (2-3).
The number n 1 of repeating units represented by the general formula (1) and the number n 2 of repeating units represented by the general formula (2) satisfy the following formula (i). Polyarylate resin.
0.30 ≦ n 1 / (n 1 + n 2 ) ≦ 0.70 (i)
Comprising a conductive substrate and a photosensitive layer;
The photosensitive layer includes a charge generator, a hole transport agent, and a binder resin,
The binder resin includes a polyarylate resin,
The polyarylate resin is an electrophotographic photoreceptor including a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2).

(In the general formulas (1) and (2), R 1 represents a hydrogen atom or a methyl group,
In the general formula (2), X represents a divalent group represented by the chemical formula (2A), (2B), (2C) or (2D). )
The electrophotographic photoreceptor according to claim 6, wherein R 1 in the general formulas (1) and (2) represents a methyl group.
The repeating unit represented by the general formula (1) is a repeating unit represented by the chemical formula (1-1),
The electrophotographic photosensitive member according to claim 6, wherein the repeating unit represented by the general formula (2) is a repeating unit represented by the chemical formula (2-1), (2-2), or (2-3). body.
The repeating unit represented by the general formula (1) is a repeating unit represented by the chemical formula (1-1),
The electrophotographic photosensitive member according to claim 6, wherein the repeating unit represented by the general formula (2) is a repeating unit represented by the chemical formula (2-3).
The number n 1 of repeating units represented by the general formula (1) and the number n 2 of repeating units represented by the general formula (2) satisfy the following formula (i). Electrophotographic photoreceptor.
0.30 ≦ n 1 / (n 1 + n 2 ) ≦ 0.70 (i)
The electrophotographic photosensitive member according to claim 6, wherein the hole transport agent includes a compound represented by the general formula (10), (11), or (12).

(In the general formula (10),
R 101 and R 108 are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a phenyl group optionally having an alkyl group having 1 to 8 carbon atoms, or 1 or more carbon atoms. Represents 8 or less alkoxy groups,
R 103 , R 104 , R 105 , R 106 and R 107 may each independently have a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkyl group having 1 to 8 carbon atoms. Represents a phenyl group or an alkoxy group having 1 to 8 carbon atoms, or two adjacent ones of R 103 , R 104 , R 105 , R 106 and R 107 are bonded to each other to have 5 to 7 carbon atoms May represent cycloalkane,
R 102 and R 109 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms,
b 1 and b 2 each independently represents an integer of 0 or more and 5 or less. )

(In the general formula (11),
R 111 and R 112 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a phenyl group,
R 113 , R 114 , R 115 , R 116 , R 117 and R 118 each independently represents an alkyl group having 1 to 8 carbon atoms or a phenyl group,
d 1 and d 2 each independently represent 0 or 1,
d 3 , d 4 , d 5 and d 6 each independently represents an integer of 0 or more and 5 or less,
d 7 and d 8 each independently represents an integer of 0 or more and 4 or less. )

(In the general formula (12),
R 121 , R 122 , R 123 , R 124 , R 125 and R 126 each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or an alkoxy group having 1 to 8 carbon atoms,
e 1 , e 2 , e 4 and e 5 each independently represents an integer of 0 or more and 5 or less,
e 3 and e 6 each independently represents an integer of 0 or more and 4 or less. )
The hole transport agent contained in the photosensitive layer is only one kind, and the hole transport agent is a compound represented by the general formula (10), (11) or (12). The electrophotographic photoreceptor described in 1.
The hole transport agent contained in the photosensitive layer is only one kind, and the hole transport agent is a compound represented by the general formula (10), (11) or (12),
The repeating unit represented by the general formula (1) is a repeating unit represented by the chemical formula (1-1),
The electrophotographic photosensitive member according to claim 11, wherein the repeating unit represented by the general formula (2) is a repeating unit represented by the chemical formula (2-3).
The photosensitive layer includes a charge generation layer and a charge transport layer,
The charge generation layer includes the charge generation agent,
The electrophotographic photosensitive member according to claim 6, wherein the charge transport layer includes the hole transport agent and the binder resin.
The electrophotographic photosensitive member according to claim 14, wherein the charge transport layer further contains an electron acceptor compound.