Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

To provide an electrophotographic photoreceptor that prevents separation and floating of a surface protective layer from a charge transport layer.SOLUTION: An electrophotographic photoreceptor comprises: a charge transport layer that contains a polyester resin (1) having a dicarboxylic acid represented by the formula (A) and diol represented by the formula (B), and a charge transport material; and a surface protective layer that is provided on the charge transport layer, contains a hardening agent having one of a guanamine compound and a melamine compound, and a reactive group-containing charge transport material having at least one substituent selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses "an electrophotographic photoreceptor comprising a conductive support and a photosensitive layer provided on the conductive support, in which an electrostatic latent image is formed by exposing the uniformly charged photosensitive layer to light corresponding to image information, wherein the surface free energy (γ) of the surface of the photosensitive layer is 20 mN / m or more and 35 mN / m or less."

[0003] Patent Document 2 discloses "an electrophotographic photoreceptor comprising a conductive support and a photosensitive layer disposed on the conductive support, the photosensitive layer comprising a first layer formed by thermally curing a first thermosetting resin composition containing a phenolic resin, and a second layer disposed adjacent to the first layer and formed by thermally curing a second thermosetting resin composition containing at least one modified phenolic resin selected from the group consisting of alkyl-modified phenolic resins, acrylic-modified phenolic resins, ester-modified phenolic resins, amide-modified phenolic resins, and urethane-modified phenolic resins." Patent Document 3 discloses an "electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, characterized in that the photosensitive layer contains a resin having a polysiloxane component and contains a polyarylate resin." Patent Document 4 discloses an image forming apparatus including "an electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in this order on a conductive substrate, charging means for charging the electrophotographic photoreceptor, electrostatic latent image forming means for forming an electrostatic latent image on the charged electrophotographic photoreceptor, developing means for forming a toner image by developing the electrostatic latent image formed on the electrophotographic photoreceptor with toner, transfer means for transferring the toner image to a transfer medium, and residual toner removing means for removing toner remaining on the electrophotographic photoreceptor after transfer of the toner image, wherein the surface protective layer of the electrophotographic photoreceptor has a surface free energy of 10 mN / m or more and 30 mN / m or less, the toner in the developing means is a toner containing silica, and the toner removing means comprises a blade member having a base layer and an edge layer having a type A durometer hardness of HsA75 or more and HsA90 or less at 23° C. and higher than the hardness of the base layer." Patent Document 5 discloses "an electrophotographic photoreceptor having a conductive substrate, a photosensitive layer provided on the conductive substrate, and a surface protective layer provided on the photosensitive layer, the surface protective layer being composed of a cured film of a composition containing a charge transport material and at least one compound selected from a compound having a guanamine structure and a compound having a melamine structure, the surface protective layer having a surface free energy of 45 mN / m or more and 95 mN / m or less." Patent Document 6 discloses an electrophotographic photoreceptor having "a conductive substrate, and a single-layer photosensitive layer provided on the conductive substrate, the photosensitive layer including a binder resin, a charge generating material, a hole transport material, and an electron transport material represented by a specific general formula, and having a surface free energy of 24 mN / m or more and 30 mN / m or less when measured on the outer peripheral surface side of the photosensitive layer." Patent Document 7 discloses an electrophotographic photoreceptor comprising: a conductive substrate; and a photosensitive layer, the photosensitive layer containing a charge generating agent, a hole transport agent, a first resin, and a second resin different from the first resin, the first resin and the second resin being contained in the same layer, the content of the first resin relative to the total mass of the first resin and the second resin being 50% or more and less than 100%, the first resin being a polyarylate resin, the polyarylate resin having repeating units represented by formulae (1), (2), (3), and (4), and the content of the repeating unit represented by formula (3) relative to the total number of repeating units represented by formulae (1) and (3) being more than 0% and less than 20%. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-205542 A [Patent Document 2] JP 2007-057603 A [Patent Document 3] JP 2009-037229 A [Patent Document 4] JP 2010-231086 A [Patent Document 5] JP 2013-195710 A [Patent Document 6] JP 2017-167423 A [Patent Document 7] JP 2022-181413 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, in a laminated electrophotographic photoreceptor having a surface protective layer containing at least one of a guanamine compound and a melamine compound curing agent and at least one reactive group-containing charge transport material having at least one substituent selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH, the adhesion at the interface between the surface protective layer and the charge transport layer is low, and when the surface protective layer is thinned, the surface protective layer may peel off or float from the charge transport layer. Therefore, in the present embodiment, the objective is to provide an electrophotographic photoreceptor having the above-mentioned surface protective layer, which suppresses peeling and floating of the surface protective layer from the charge transport layer even when the surface protective layer is thinned, compared to when the charge transport layer does not contain the polyester resin (1) but contains a polycarbonate resin. [Means for solving the problem]

[0006] Specific means for solving the above problems include the following aspects.

[0007] <1> A conductive substrate; an undercoat layer provided on the conductive substrate; a charge generating layer provided on the undercoat layer; a charge transport layer provided on the charge generating layer, the charge transport layer comprising a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B), and a charge transport material; a surface protective layer provided on the charge transport layer, the surface protective layer containing at least one of a guanamine compound and a melamine compound curing agent, and at least one reactive group-containing charge transport material having at least one substituent selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH; An electrophotographic photoreceptor comprising: [ka] (In the above formula (A), n 1 is 1, 2 or 3, and n 1 m1 are each independently 0, 1, 2, 3 or 4; m 1 Ra 1 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In the formula (B), Rb 1 and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group. <2> The surface free energy E OCL and the surface free energy E in the charge transport layer. CT The difference between OCL -E CT ) is 6 mN / m or more and 10 mN / m or less, <1> The electrophotographic photoreceptor according to claim 1. <3> The surface protection layer has a surface free energy E OCL is 38 mN / m or more and 42 mN / m or less, <2> The electrophotographic photoreceptor according to claim 1. <4> The charge transport layer has a surface free energy E CT is 32 mN / m or more and 35 mN / m or less, <2> or <3> The electrophotographic photoreceptor according to claim 1. <5> The reactive group-containing charge transport material has -OH as the substituent. <1> ~ <4> 13. The electrophotographic photoreceptor according to claim 12, <6> The content of the polyester resin (1) is 35% by mass or more and 65% by mass or less based on the total solid content of the charge transport layer. <1> ~ <5> 13. The electrophotographic photoreceptor according to claim 12, <7> The above <1> ~ <6> The electrophotographic photoreceptor according to any one of the above items is provided, A process cartridge that is detachably attached to an image forming apparatus. <8> The above <1> ~ <6> and an electrophotographic photoreceptor according to any one of the above items. a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; The electrostatic latent image formed on the surface of the electrophotographic photoreceptor is developed with a developer containing a toner. a developing device for forming a toner image by using the toner; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising: Effect of the Invention

[0008] <1> or <5> According to the invention, there is provided a laminated electrophotographic photoreceptor having a surface protective layer, which is capable of suppressing peeling and lifting of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner, as compared with a case in which the charge transport layer does not contain the polyester resin (1) but contains a polycarbonate resin. <2> According to the present invention, in a laminated electrophotographic photoreceptor having a surface protective layer, the surface free energy E OCL and the surface free energy E in the charge transport layer. CT The difference between OCL -E CT ) is less than 6 mN / m or more than 10 mN / m, an electrophotographic photoreceptor is provided which suppresses peeling and lifting of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. <3> According to the present invention, in a laminated electrophotographic photoreceptor having a surface protective layer, the surface protective layer has a surface free energy E OCLIn comparison with the case where the surface protective layer has a surface tension of less than 38 mN / m or more than 42 mN / m, an electrophotographic photoreceptor is provided which suppresses peeling and lifting of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. <4> According to the present invention, in the multi-layer electrophotographic photoreceptor having a surface protective layer, the charge transport layer has a surface free energy E CT In comparison with the case where the surface protective layer has a thickness of less than 32 mN / m or more than 35 mN / m, an electrophotographic photoreceptor is provided which suppresses peeling and lifting of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. <6> According to the invention, in a laminated electrophotographic photoreceptor having a surface protective layer, an electrophotographic photoreceptor is provided which suppresses peeling and floating of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner, compared to when the content of the polyester resin (1) is less than 35 mass % or more than 65 mass % relative to the total solid content of the charge transport layer. <7> or <8> According to the invention, there is provided a process cartridge or an image forming apparatus including an electrophotographic photoreceptor in which the charge transport layer does not contain the polyester resin (1) and instead contains a polycarbonate resin, and which suppresses peeling and floating of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a partial cross-sectional view showing an example of a layer structure of the electrophotographic photoreceptor according to the present embodiment. [Diagram 2] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic configuration diagram illustrating another example of an image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described. These descriptions and examples are merely illustrative of the embodiments, and are not intended to limit the scope of the embodiments.

[0011] In the present disclosure, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively.

[0012] In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[0013] In the present disclosure, the term "step" includes not only an independent step, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0014] When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0015] In the present disclosure, each component may contain multiple types of corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified.

[0016] In the present disclosure, the particles corresponding to each component may include multiple types. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0017] In the present disclosure, the term "(meth)acrylic" means either "acrylic" or "methacrylic".

[0018] In the present disclosure, unless otherwise specified, the alkyl group includes any of straight-chain, branched and cyclic alkyl groups.

[0019] <Electrophotographic photoreceptor> The electrophotographic photoreceptor according to the present embodiment includes a conductive substrate, an undercoat layer provided on the conductive substrate, a charge generating layer provided on the undercoat layer, a charge transport layer provided on the charge generating layer and containing a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B) and a charge transport material, and a surface protective layer provided on the charge transport layer and being a cured film of a composition containing a curing agent having at least one of a guanamine compound and a melamine compound, and at least one reactive group-containing charge transport material having at least one substituent selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH.

[0020] [ka] In formula (A), n 1 is 1, 2 or 3, and n 1 m 1 are each independently 0, 1, 2, 3 or 4; m 1 Ra 1 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (B), Rb 1 and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; Rb 1 and Rb2 may be bonded to form a cyclic alkyl group.

[0021] 1 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment. The photoreceptor 107A has a structure in which an undercoat layer 101 is provided on a conductive substrate 104, and a charge generation layer 102, a charge transport layer 103, and a surface protection layer 106 are sequentially formed thereon. The photoreceptor 107A has an organic photoreceptor layer 105 whose functions are separated into the charge generation layer 102 and the charge transport layer 103. Although not shown, the photoreceptor 107A may have an intermediate layer between the conductive substrate 104 and the undercoat layer 101, or between the undercoat layer 101 and the charge generation layer 102.

[0022] As a technique for improving the abrasion resistance of the photosensitive layer, it is known to use a polyester resin having a rigid skeleton with repeating aromatic rings as the binder resin of the charge transport material. However, when a polyester resin having a rigid skeleton with repeating aromatic rings is used as the binder resin of the charge transport layer, the molecular dispersion of the charge transport material may decrease, and as a result, the electrical properties of the photoreceptor may not satisfy the expected value. In addition, when a polyester resin having a rigid skeleton with repeating aromatic rings with low polarity is used as the binder resin of the charge transport layer, when a surface protection layer having a highly polar reactive group is applied on top, the surface wettability of the charge transport layer is low, and the adhesion between the surface protection layer and the charge transport layer after heating and drying is reduced, and peeling and lifting of the surface protection layer from the charge transport layer may occur. This phenomenon is particularly noticeable when the surface protection layer is thin.

[0023] In contrast, in the electrophotographic photoreceptor according to the present embodiment, the peeling and lifting of the surface protective layer from the charge transport layer can be suppressed. The mechanism of this action is not necessarily clear, but is presumed to be as follows. The electrophotographic photoreceptor according to the present embodiment contains a polyester resin (1) having a dicarboxylic acid unit (A) represented by the above-mentioned formula (A) and a diol unit (B) represented by the formula (B) in the charge transport layer. Therefore, the surface of the charge transport layer has wettability. In addition, the composition constituting the cured film which is the surface protective layer contains a curing agent having at least one of a guanamine compound and a melamine compound, and at least one of the reactive group-containing charge transport materials having the above-mentioned specific substituent. Therefore, the surface of the surface protective layer also has a suitable wettability. This increases the affinity at the interface between the charge transport layer and the surface protective layer, and it is considered that even when the surface protective layer is thinned, peeling and lifting of the surface protective layer from the charge transport layer is suppressed.

[0024] [Characteristics of electrophotographic photoreceptors] Surface free energy E of the surface protective layer OCL and the surface free energy E of the charge transport layer CT The difference between OCL -E CT ) is preferably 6 mN / m or more and 10 mN / m or less, and more preferably 5 mN / m or more and 9 mN / m or less. The difference (E OCL -E CT When the surface protective layer has a surface tension of 10 mN / m or less, the affinity at the interface between the surface protective layer and the charge transport layer is prevented from decreasing, and the adhesiveness at the interface between the surface protective layer and the charge transport layer is excellent. The difference (E OCL -E CT When the interfacial strength is 6 mN / m or more, the affinity at the interface between the charge transport layer and the surface protective layer is high, and the adhesiveness at the interface between the surface protective layer and the charge transport layer is excellent.

[0025] The surface protection layer has a surface free energy E OCL is preferably 38 mN / m or more and 42 mN / m or less, and more preferably 39 mN / m or more and 41 mN / m or less. Surface free energy E OCL When the surface tension is 38 mN / m or more, a decrease in the interfacial adhesion energy between the surface protective layer and the charge transport layer is easily suppressed. Surface free energy EOCL When the surface tension is 42 mN / m or less, the adhesion at the interface between the surface protective layer and the hydrophobic charge transport layer is excellent, but the activity of the surface protective layer is high and the toner cleaning property is unlikely to deteriorate.

[0026] The charge transport layer has a surface free energy E CT is preferably 32 mN / m or more and 35 mN / m or less, and more preferably 32 mN / m or more and 34 mN / m or less. Surface free energy E CT If the compressive strength is 32 mN / m or more, the wettability of the surface protective layer decreases, and a decrease in the film-forming property of the surface protective layer is easily suppressed. Surface free energy E CT When the surface tension is 35 mN / m or less, the wettability with the underlying charge generating layer is prevented from being deteriorated. Furthermore, the adhesion at the interface between the surface protective layer and the charge transport layer is excellent, but the deterioration of the electrical properties is prevented.

[0027] Surface free energy E OCL , and E CT The contact angles of water and n-hexadecane of each film are measured using a contact angle meter CA-X (manufactured by Kyowa Interface Science Co., Ltd.), and the contact angles are calculated using the OWRK method.

[0028] Surface free energy E CT The method for making the content of the dicarboxylic acid unit (A) represented by the above formula (A) and the diol unit (B) represented by the above formula (B) may be included in the charge transport layer in a predetermined amount.

[0029] Surface free energy E OCL The method for achieving the above range is not particularly limited, and an example thereof includes a method for forming the surface protective layer into a cured film of a composition containing at least one of a guanamine compound and a melamine compound curing agent, and a reactive group-containing charge transport material having at least one of -OH and -OCH3 substituents.

[0030] [Polyester resin (1)] The polyester resin (1) has at least a dicarboxylic acid unit (A) represented by formula (A) and a diol unit (B) represented by formula (B). The polyester resin (1) may contain a dicarboxylic acid unit other than the dicarboxylic acid unit (A). The polyester resin (1) may contain a diol unit other than the diol unit (B).

[0031] The dicarboxylic acid unit (A) is a structural unit represented by the following formula (A).

[0032] [ka]

[0033] In formula (A), n 1 is 1, 2 or 3, and n 1 m 1 are each independently 0, 1, 2, 3 or 4; m 1 Ra 1 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0034] In formula (A), n 1 is 1, 2 or 3, with 2 being preferred. n 1 When m is 2, the two benzene rings in formula (A) are 1 and Ra 1 may be the same benzene ring or different benzene rings. n 1 When m is 3, the three benzene rings in formula (A) are 1 and Ra 1 may be the same benzene ring or different benzene rings.

[0035] In formula (A), n 1 When is 2 or 3, the linking position between the benzene rings may be any of ortho, meta and para, and is preferably meta or para.

[0036] In formula (A), m 1 is 0, 1, 2, 3 or 4, preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. m 1 When is 2, two Ra bonds to the same benzene ring 1 may be the same type of group or different types of groups. m 1 When is 3, three Ra are bonded to the same benzene ring. 1 may be the same type of group or different types of groups. m 1 When is 4, four Ra ​​are bonded to the same benzene ring. 1 may be the same type of group or different types of groups.

[0037] In formula (A), the alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 or 2. In the formula (A), the aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The aryl group preferably has 6 to 10 carbon atoms, more preferably 6 to 9 carbon atoms. In formula (A), the alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0038] In formula (A), examples of the linear alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. Examples of branched alkyl groups having 3 to 10 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, and a sec-octyl group. , tert-octyl group, isononyl group, sec-nonyl group, tert-nonyl group, isodecyl group, sec-decyl group, and tert-decyl group. Examples of the cyclic alkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl group formed by linking these monocyclic alkyl groups.

[0039] In the formula (A), examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0040] In the formula (A), examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. In formula (A), examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. In the formula (A), examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0041] In formula (A), m 1 When is 1, 2, 3 or 4, Ra 1is preferably a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 3 to 6 carbon atoms, more preferably a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 or 4 carbon atoms, and more preferably a methyl group or an ethyl group.

[0042] Specific examples of the dicarboxylic acid unit (A) include the dicarboxylic acid units (A-1) to (A-13), but the dicarboxylic acid unit (A) is not limited thereto.

[0043] [ka]

[0044] [ka]

[0045] As the dicarboxylic acid unit (A), the above specific examples (A-1), (A-7) and (A-12) are preferred, with (A-12) being the most preferred.

[0046] The dicarboxylic acid unit (A) contained in the polyester resin (1) may be of one type or of two or more types.

[0047] The diol unit (B) is a structural unit represented by the following formula (B).

[0048] [ka]

[0049] In formula (B), Rb 1 and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb8 , Rb 9 and Rb 10 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group.

[0050] In formula (B), Rb 1 and Rb 2 The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 15 carbon atoms, more preferably has 1 to 12 carbon atoms, and further preferably has 1 to 10 carbon atoms. In formula (B), Rb 1 and Rb 2 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6 to 9. In formula (B), Rb 1 and Rb 2 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either monocyclic or polycyclic, and the alkyl group in the aralkyl group having 7 to 20 carbon atoms may be either linear, branched, or cyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6 to 9. The number of carbon atoms in the alkyl group is preferably 1 to 6, and more preferably 1 to 5, and even more preferably 1 to 4. In formula (B), Rb 1 and Rb 2 The number of carbon atoms in a cyclic alkyl group that may be formed by bonding with is preferably 5 or more and 15 or less, and more preferably 6 or more and 12 or less.

[0051] In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9and Rb 10 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 The aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6 to 9. In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 The aryl group in the aralkyl group having 7 to 20 carbon atoms may be either monocyclic or polycyclic, and the alkyl group in the aralkyl group having 7 to 20 carbon atoms may be either linear, branched, or cyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6 to 9. The number of carbon atoms in the alkyl group is preferably 1 to 6, and more preferably 1 to 5, and even more preferably 1 to 4. In formula (B), Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 The alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0052] In formula (B), examples of the straight-chain alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group. Examples of the branched alkyl group having 3 to 20 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, an isododecyl group, a sec-dodecyl group, a tert-dodecyl group, a tert-tetradecyl group, and a tert-pentadecyl group. Examples of the cyclic alkyl group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and the like, as well as polycyclic (e.g., bicyclic, tricyclic, spirocyclic) alkyl groups formed by linking these monocyclic alkyl groups.

[0053] In the formula (B), examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a biphenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0054] In formula (B), examples of the aralkyl group having 7 to 20 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, a 4-phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a phenylheptyl group, a phenyloctyl group, a phenylnonyl group, a naphthylmethyl group, a naphthylethyl group, an anthrathylmethyl group, and a phenyl-cyclopentylmethyl group.

[0055] In the formula (B), examples of the linear alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group. In formula (B), examples of the branched alkoxy group having 3 to 6 carbon atoms include an isopropoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a sec-hexyloxy group, and a tert-hexyloxy group. In the formula (B), examples of the cyclic alkoxy group having 3 to 6 carbon atoms include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0056] In formula (B), Rb 1 and Rb 2 each independently represents a hydrogen atom, a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms; 1 and Rb 2 and preferably combine to form a cyclic alkyl group having 5 to 12 carbon atoms. In formula (B), Rb 1 and Rb 2 are each independently a hydrogen atom, a linear alkyl group having 1 to 10 carbon atoms, or a branched alkyl group having 1 to 10 carbon atoms; 1 and Rb 2 and more preferably bonded to form a cyclic alkyl group having 5 to 12 carbon atoms. In formula (B), Rb 1 and Rb 2 It is more preferable that each independently represents a hydrogen atom, a linear alkyl group having from 1 to 10 carbon atoms, or a branched alkyl group having from 1 to 10 carbon atoms.

[0057] In formula (B), Rb 1 and Rb 2At least one of Rb is a linear alkyl group having 4 to 10 carbon atoms, a branched alkyl group having 4 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms, 1 and Rb 2 and preferably combine to form a cyclic alkyl group having 5 to 12 carbon atoms. In formula (B), Rb 1 and Rb 2 It is more preferable that at least one of them is a linear alkyl group having 4 to 10 carbon atoms or a branched alkyl group having 4 to 10 carbon atoms. Rb 1 and Rb 2 If at least one of Rb is as above, 1 and Rb 2 The other is preferably a hydrogen atom or a linear alkyl group having 1 to 3 carbon atoms.

[0058] The diol unit (B) is preferably a structural unit represented by the following formula (B').

[0059] [ka]

[0060] Rb in formula (B') 1 , Rb 2 , Rb 4 and Rb 9 respectively represent Rb in formula (B). 1 , Rb 2 , Rb 4 and Rb 9 The same definition and preferred form are also the same.

[0061] The diol unit (B) is, in the formula (B'), Rb 1 is a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group having 3 carbon atoms, and Rb 2is a linear alkyl group having 4 to 10 carbon atoms, a branched alkyl group having 4 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms, and Rb 4 and Rb 9 are preferably each independently a hydrogen atom or a methyl group; Rb 1 is a hydrogen atom or a methyl group, and Rb 2 is a linear alkyl group having 4 to 10 carbon atoms or a branched alkyl group having 4 to 10 carbon atoms, and Rb 4 and Rb 9 are each independently a hydrogen atom or a methyl group.

[0062] Specific examples of the diol unit (B) include diol units (B-1) to (B-38), but the diol unit (B) is not limited thereto.

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka] JPEG2025045879000013.jpg4157

[0068] The diol unit (B) contained in the polyester resin (1) may be of one type or of two or more types.

[0069] The mass proportion of the dicarboxylic acid unit (A) in the polyester resin (1) is preferably 15 mass % or more and 60 mass % or less. When the mass proportion of the dicarboxylic acid unit (A) is 15 mass% or more, the photosensitive layer has good abrasion resistance. From this viewpoint, the mass proportion of the dicarboxylic acid unit (A) is more preferably 20 mass% or more, and further preferably 25 mass% or more. When the mass proportion of the dicarboxylic acid unit (A) is 60 mass% or less, peeling of the photosensitive layer can be further suppressed. From this viewpoint, the mass proportion of the dicarboxylic acid unit (A) is more preferably 55 mass% or less, and further preferably 50 mass% or less.

[0070] The mass proportion of the diol unit (B) in the polyester resin (1) is preferably 25 mass % or more and 60 mass % or less. When the mass proportion of the diol unit (B) is 25 mass% or more, peeling of the photosensitive layer can be further suppressed. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 30 mass% or more, and further preferably 35 mass% or more. When the mass ratio of the diol unit (B) is 60 mass % or less, the coating material for forming the photosensitive layer It is possible to improve the abrasion resistance while maintaining the solubility in the fabric liquid. From this viewpoint, the mass proportion of the diol unit (B) is more preferably 55 mass % or less, and further preferably 50 mass % or less.

[0071] The polyester resin (1) may contain dicarboxylic acid units other than the dicarboxylic acid units (A).

[0072] Examples of the other dicarboxylic acid units include a dicarboxylic acid unit (C) represented by the following formula (C).

[0073] [ka]

[0074] In formula (C), Rc 1 , Rc 2 , Rc 3 , Rc 4 , Rc 5 and Rc 6 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0075] In formula (C), the alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. In the formula (C), the aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6 to 9. In formula (C), the alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0076] Examples of the alkyl group, aryl group and alkoxy group in formula (C) include the same groups as those mentioned for formula (A).

[0077] In formula (C), Rc 1 , Rc 2 , Rc 3 , Rc 4 , Rc 5 and Rc 6 are each independently preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 1 to 4 carbon atoms, even more preferably a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom.

[0078] As the dicarboxylic acid unit (C), a 2,6-naphthalenedicarboxylic acid unit (the following formula (C-1)) is most preferred.

[0079] [ka]

[0080] The dicarboxylic acid unit (C) contained in the polyester resin (1) may be of one type or of two or more types.

[0081] When the polyester resin (1) has the dicarboxylic acid unit (C), the mass proportion of the dicarboxylic acid unit (C) in the polyester resin (1) is preferably from 1 mass % to 20 mass %.

[0082] Examples of the other dicarboxylic acid units include a dicarboxylic acid unit (D) represented by the following formula (D).

[0083] [ka]

[0084] In formula (D), Rd 1 , Rd 2 , Rd 3 , Rd 4 , Rd 5 , Rd 6 , Rd 7 and Rd 8 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0085] In formula (D), the alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. In the formula (D), the aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The aryl group preferably has 6 to 10 carbon atoms, more preferably 6 to 9 carbon atoms. In formula (D), the alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0086] Examples of the alkyl group, aryl group and alkoxy group in formula (D) include the same groups as those mentioned for formula (A).

[0087] In formula (D), Rd 1 , Rd 2 , Rd 3 , Rd 4 , Rd 5 , Rd 6 , Rd 7 and Rd 8 are each independently preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 1 to 4 carbon atoms, even more preferably a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom.

[0088] The dicarboxylic acid unit (D) is preferably a structural unit represented by the following formula (D'): stomach.

[0089] [ka]

[0090] Rd in formula (D') 1 , Rd 2 , Rd 3 and Rd 4 are Rd in formula (D),1 , Rd 2 , Rd 3 and Rd 4 The same definition and preferred form are also the same.

[0091] As the dicarboxylic acid unit (D), a diphenyl ether-4,4'-dicarboxylic acid unit (the following formula (D-1)) is most preferred.

[0092] [ka]

[0093] The dicarboxylic acid unit (D) contained in the polyester resin (1) may be of one type or of two or more types.

[0094] When the polyester resin (1) has the dicarboxylic acid unit (D), the mass proportion of the dicarboxylic acid unit (D) in the polyester resin (1) is preferably from 1 mass % to 20 mass %.

[0095] Examples of other dicarboxylic acid units include aliphatic dicarboxylic acid units (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acid units (e.g., cyclohexanedicarboxylic acid), and lower alkyl ester units thereof (e.g., having 1 to 5 carbon atoms). The polyester resin (1) may contain one or more types of dicarboxylic acid units.

[0096] The polyester resin (1) may contain diol units other than the diol units (B).

[0097] An example of the other diol unit is a diol unit (E) represented by the following formula (E).

[0098] [ka]

[0099] In formula (E), Re 1 , Re 2 , Re 3 , Re 4 , Re 5 , Re 6 , Re 7 and R e 8 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0100] In formula (E), the alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. In the formula (E), the aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The aryl group preferably has 6 to 10 carbon atoms, more preferably 6 to 9 carbon atoms. In formula (E), the aryl group in the aralkyl group having 7 to 20 carbon atoms may be either monocyclic or polycyclic, and the alkyl group in the aralkyl group having 7 to 20 carbon atoms may be either linear, branched, or cyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6 to 9. The number of carbon atoms in the alkyl group is preferably 1 to 6, and more preferably 1 to 5, and even more preferably 1 to 4. In formula (E), the alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0101] Examples of the alkyl group, aryl group, aralkyl group and alkoxy group in formula (E) include the same groups as those exemplified for formula (B).

[0102] In formula (E), Re1 , Re 2 , Re 3 , Re 4 , Re 5 , Re 6 , Re 7 and Re 8 are each independently preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 1 to 4 carbon atoms, even more preferably a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

[0103] The diol unit (E) is preferably a structural unit represented by the following formula (E').

[0104] [ka]

[0105] Re in formula (E') 1 , Re 2 , Re 3 and Re 4 are the Re in formula (E), 1 , Re 2 , Re 3 and Re 4 The same definition and preferred form are also the same.

[0106] The diol unit (E) is most preferably any one of the following formulae (E-1) to (E-3).

[0107] [ka]

[0108] The diol unit (E) contained in the polyester resin (1) may be of one type or of two or more types.

[0109] When the polyester resin (1) has the diol unit (E), the mass proportion of the diol unit (E) in the polyester resin (1) is preferably from 1 mass % to 20 mass %.

[0110] An example of the other diol unit is a diol unit (F) represented by the following formula (F).

[0111] [ka]

[0112] In formula (F), Rf 1 , Rf 2 , Rf 3 , Rf 4 , Rf 5 , Rf 6 , Rf 7 and Rf 8 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0113] In formula (F), the alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 or 2 carbon atoms. In the formula (F), the aryl group having 6 to 12 carbon atoms may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6 to 9. In formula (F), the aryl group in the aralkyl group having 7 to 20 carbon atoms may be either monocyclic or polycyclic, and the alkyl group in the aralkyl group having 7 to 20 carbon atoms may be either linear, branched, or cyclic. The number of carbon atoms in the aryl group is preferably 6 to 10, and more preferably 6 to 9. The number of carbon atoms in the alkyl group is preferably 1 to 6, and more preferably 1 to 5, and even more preferably 1 to 4. In formula (F), the alkyl group in the alkoxy group having 1 to 6 carbon atoms may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group in the alkoxy group having 1 to 6 carbon atoms is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0114] Examples of the alkyl group, aryl group, aralkyl group and alkoxy group in formula (F) include the same groups as those exemplified for formula (B).

[0115] In formula (F), Rf 1 , Rf 2 , Rf 3 , Rf 4 , Rf 5 , Rf 6 , Rf 7 and Rf 8 are each independently preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, or a branched alkyl group having 1 to 4 carbon atoms, even more preferably a hydrogen atom, a linear alkyl group having 1 to 3 carbon atoms, or a branched alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

[0116] The diol unit (F) is preferably a structural unit represented by the following formula (F').

[0117] [ka]

[0118] Rf in formula (F') 1 , Rf 2 , Rf 3 and Rf 4 are Rf in formula (F), 1 , Rf 2 , Rf 3 and Rf 4 The same definition and preferred form are also the same.

[0119] As the diol unit (F), a bis(4-hydroxyphenyl)ether unit (the following formula (F-1)) is most preferred.

[0120] [ka]

[0121] The diol unit (F) contained in the polyester resin (1) may be of one type or of two or more types.

[0122] When the polyester resin (1) has the diol unit (F), the mass proportion of the diol unit (F) in the polyester resin (1) is preferably from 1 mass % to 20 mass %.

[0123] Examples of other diol units include aliphatic diol units (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol) and alicyclic diol units (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A). The polyester resin (1) may contain one or more types of these diol units.

[0124] Examples of the method for producing the polyester resin (1) include an interfacial polymerization method, a solution polymerization method, and a melt polymerization method.

[0125] The ends of the polyester resin (1) may be capped or modified with a terminal capping agent or a molecular weight regulator used during production. Examples of the terminal capping agent or the molecular weight regulator include Examples of the monohydric phenol include monohydric phenols, monoacid chlorides, monohydric alcohols, and monocarboxylic acids. Examples of monohydric phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-tert-butylphenol, m-tert-butylphenol, p-tert-butylphenol, pentylphenol, hexylphenol, octylphenol, nonylphenol, 2,6-dimethylphenol derivatives, 2-methylphenol derivatives, o-phenylphenol, m-phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3,6-trimethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2-phenyl-2-(4-hydroxyphenyl)propane, 2-phenyl-2-(2-hydroxyphenyl)propane, and 2-phenyl-2-(3-hydroxyphenyl)propane. Examples of the monovalent acid chloride include monofunctional acid halides such as benzoyl chloride, benzoic acid chloride, methanesulfonyl chloride, phenyl chloroformate, acetic acid chloride, butyric acid chloride, octylic acid chloride, benzoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride, and substituted versions of these. Examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol. Examples of the monovalent carboxylic acid include acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

[0126] The content of the polyester resin (1) is preferably from 35% by mass to 65% by mass, and more preferably from 40% by mass to 60% by mass, based on the total solid content of the charge transport layer.

[0127] [Conductive substrate] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of conductive substrates include paper, resin films, belts, etc. coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is less than Ωcm.

[0128] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiating with laser light. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for extending the life of the conductive substrate since it suppresses the occurrence of defects due to unevenness on the surface.

[0129] Examples of methods for roughening the surface include wet honing, which involves spraying an abrasive suspended in water onto the conductive substrate; centerless grinding, in which the conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0130] As a method for roughening the surface, there can be mentioned a method in which, without roughening the surface of the conductive substrate, a conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0131] In the roughening treatment by anodization, an oxide film is formed on the surface of a conductive substrate made of metal (e.g., aluminum) by anodizing the substrate in an electrolyte solution using the substrate as the anode. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodization is chemically active in its original state, easily contaminated, and has a large resistance variation depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film, in which the micropores of the oxide film are filled by volume expansion caused by hydration reaction in pressurized steam or boiling water (metal salts such as nickel may be added) to change the film into a more stable hydrated oxide.

[0132] The thickness of the anodic oxide film is preferably, for example, from 0.3 μm to 15 μm. If the thickness is within this range, the film tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential due to repeated use.

[0133] The conductive substrate may be subjected to a treatment with an acidic treatment solution or a boehmite treatment. Treatment with an acid treatment liquid is carried out, for example, as follows. First, an acid treatment liquid containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The compounding ratios of phosphoric acid, chromic acid, and hydrofluoric acid in the acid treatment liquid are, for example, in the range of 10% by mass to 11% by mass for phosphoric acid, 3% by mass to 5% by mass for chromic acid, and 0.5% by mass to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42° C. to 48° C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0134] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the material with heated steam at 90°C to 120°C for 5 to 60 minutes. The thickness of the coating is preferably 0.1 μm to 5 μm. This may be further anodized using an electrolyte solution having low coating solubility, such as adipic acid, boric acid, borates, phosphates, phthalates, maleates, benzoates, tartrates, or citrates.

[0135] [Sublayer] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0136] For example, inorganic particles have a powder resistance (volume resistivity) of 1×10 2 Ωcm or more 1×10 11 Examples of such particles include inorganic particles with a particle size of Ωcm or less. Among these, examples of inorganic particles having the above-mentioned resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0137] The specific surface area of ​​inorganic particles by the BET method is, for example, 10 m 2 / g or higher is preferable. The volume average particle size of the inorganic particles is, for example, from 50 nm to 2000 nm (preferably from 60 nm to 1000 nm).

[0138] The content of the inorganic particles is, for example, preferably from 10% by mass to 80% by mass, more preferably from 40% by mass to 80% by mass, based on the binder resin.

[0139] The inorganic particles may be surface-treated. Two or more types of inorganic particles having different surface treatments or different particle sizes may be used in combination.

[0140] Examples of the surface treatment agent include a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a surfactant, etc. In particular, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0141] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0142] Silane coupling agents may be used in combination of two or more kinds. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0143] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method.

[0144] The amount of the surface treatment agent to be used is preferably, for example, 0.5% by mass or more and 10% by mass or less based on the inorganic particles.

[0145] Here, it is preferable that the undercoat layer contains an electron accepting compound (acceptor compound) together with the inorganic particles, from the viewpoints of improving the long-term stability of electrical properties and carrier blocking properties.

[0146] Examples of the electron-accepting compound include electron-transporting substances such as quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; and diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone. In particular, the electron-accepting compound is preferably a compound having an anthraquinone structure. Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds, and more specifically, anthraquinone, alizarin, quinizarin, anthrarufin, and purpurin.

[0147] The electron accepting compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in a state of being attached to the surfaces of the inorganic particles.

[0148] The method for attaching the electron accepting compound to the surface of the inorganic particles may be, for example, a dry method or a wet method.

[0149] The dry method is, for example, a method in which an electron-accepting compound is attached to the surface of inorganic particles by dropping an electron-accepting compound directly or dissolved in an organic solvent or spraying it together with dry air or nitrogen gas while stirring inorganic particles with a mixer or the like that exerts a large shearing force. The dropping or spraying of the electron-accepting compound is preferably performed at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at 100° C. or higher. The temperature and time of baking are not particularly limited as long as electrophotographic properties can be obtained.

[0150] The wet method is a method in which, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent by stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and the inorganic particles are stirred or dispersed, and then the solvent is removed to attach the electron-accepting compound to the surface of the inorganic particles. The solvent is removed, for example, by filtration or distillation. After the solvent is removed, baking may be performed at 100°C or higher. The baking temperature and time are not particularly limited as long as electrophotographic properties are obtained. In the wet method, moisture contained in the inorganic particles may be removed before adding the electron-accepting compound, and examples of such methods include a method of removing the moisture while stirring and heating in a solvent, and a method of removing the moisture by azeotropy with the solvent.

[0151] The attachment of the electron accepting compound may be carried out before or after the inorganic particles are subjected to a surface treatment with a surface treatment agent, or the attachment of the electron accepting compound and the surface treatment with the surface treatment agent may be carried out simultaneously.

[0152] The content of the electron accepting compound is, for example, from 0.01% by mass to 20% by mass, and preferably from 0.01% by mass to 10% by mass, based on the inorganic particles.

[0153] Examples of the binder resin used in the undercoat layer include known materials such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, and epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents. Examples of the binder resin used in the undercoat layer include charge transporting resins having charge transporting groups, conductive resins (such as polyaniline, etc.), and the like.

[0154] Among these, the binder resin used in the undercoat layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and in particular, a resin obtained by reacting at least one resin selected from the group consisting of thermosetting resins such as urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, and epoxy resins, with a curing agent is preferred. When two or more of these binder resins are used in combination, the mixing ratio is set as necessary.

[0155] The undercoat layer may contain various additives for improving electrical properties, environmental stability, and image quality. Examples of the additives include known materials such as polycyclic condensation and azo-based electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, etc. As described above, silane coupling agents are used for surface treatment of inorganic particles, and may also be added to the undercoat layer as an additive.

[0156] Examples of silane coupling agents as additives include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, and the like.

[0157] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetoacetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0158] Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0159] Examples of aluminum chelate compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0160] These additives may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0161] The undercoat layer preferably has a Vickers hardness of 35 or more. The surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to between 1 / (4n) (n is the refractive index of the upper layer) and 1 / 2 of the wavelength λ of the exposure laser used in order to suppress moire images. Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. The surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, grinding, and the like.

[0162] The formation of the undercoat layer is not particularly limited, and a known formation method can be used. For example, the undercoat layer can be formed by forming a coating film of a coating solution for forming the undercoat layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary.

[0163] Examples of the solvent for preparing the coating liquid for forming the undercoat layer include known organic solvents, such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include ordinary organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0164] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming the undercoat layer include known methods such as those using a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0165] Examples of the method for applying the coating liquid for forming the undercoat layer onto the conductive substrate include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0166] The thickness of the undercoat layer is set, for example, preferably at least 15 μm, and more preferably within the range of from 20 μm to 50 μm.

[0167] [Middle layer] An intermediate layer may further be provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral, etc.), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and melamine resins. The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in the intermediate layer may be used alone or as a mixture or polycondensation product of a plurality of compounds.

[0168] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0169] The formation of the intermediate layer is not particularly limited, and a known formation method can be used. For example, the intermediate layer can be formed by forming a coating film of a coating solution for forming an intermediate layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary. The intermediate layer can be formed by any of the usual coating methods, such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating and curtain coating.

[0170] The thickness of the intermediate layer is preferably set in the range of, for example, 0.1 μm to 3 μm The intermediate layer may be used as an undercoat layer.

[0171] [Charge generation layer] The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may also be a vapor deposition layer of the charge generation material. The vapor deposition layer of the charge generation material is suitable for use with a non-coherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

[0172] Examples of charge generating materials include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; and oxide pigments. Zinc; trigonal selenium, etc.

[0173] Among these, in order to correspond to the laser exposure in the near infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material.Specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and especially titanyl phthalocyanine are more preferable.

[0174] On the other hand, in order to accommodate laser exposure in the near ultraviolet region, preferred charge generating materials include condensed aromatic pigments such as dibromoanthanthrone, thioindigo pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and bisazo pigments.

[0175] The above charge generating materials may be used when using incoherent light sources such as LEDs and organic EL image arrays that emit light at a central wavelength of 450 nm to 780 nm, but from the viewpoint of resolution, when using a thin photosensitive layer of 20 μm or less, the electric field strength in the photosensitive layer becomes high, and a decrease in charging due to charge injection from the substrate, so-called black spots, is likely to occur as an image defect. This becomes more noticeable when using charge generating materials that are p-type semiconductors such as trigonal selenium and phthalocyanine pigments and are prone to generating dark current.

[0176] In contrast, when an n-type semiconductor such as a fused aromatic pigment, a perylene pigment, or an azo pigment is used as the charge generating material, dark current is unlikely to occur, and image defects called black spots can be suppressed even when the material is made into a thin film. The n-type is determined by the polarity of the photocurrent that flows using the commonly used time-of-flight method, and those that easily pass electrons as carriers rather than holes are considered to be n-type.

[0177] The binder resin used in the charge generating layer may be selected from a wide range of insulating resins, and may also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, polysilane, and the like. Examples of binder resins include polyvinyl butyral resins, polyarylate resins (polycondensates of bisphenols and aromatic dicarboxylic acids, etc.), polycarbonate resins, polyester resins, phenoxy resins, vinyl chloride-vinyl acetate copolymers, polyamide resins, acrylic resins, polyacrylamide resins, polyvinylpyridine resins, cellulose resins, urethane resins, epoxy resins, casein, polyvinyl alcohol resins, polyvinylpyrrolidone resins, etc. Here, "insulating" refers to a material having a volume resistivity of 1×10 13 This means that the resistance is Ωcm or more. These binder resins may be used alone or in combination of two or more.

[0178] The compounding ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 by mass.

[0179] The charge generating layer may contain other known additives.

[0180] The formation of the charge generating layer is not particularly limited, and a known formation method can be used. For example, the charge generating layer can be formed by forming a coating film of a coating solution for forming the charge generating layer in which the above-mentioned components are added to a solvent, drying the coating film, and heating it as necessary. The charge generating layer can also be formed by vapor deposition of the charge generating material. Formation of the charge generating layer by vapor deposition is particularly suitable when a fused ring aromatic pigment or a perylene pigment is used as the charge generating material.

[0181] Examples of the solvent for preparing the coating liquid for forming the charge generating layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0182] Examples of methods for dispersing particles (e.g., charge generating material) in the coating liquid for forming a charge generating layer include media dispersers such as ball mills, vibration ball mills, attritors, sand mills, and horizontal sand mills, and medialess dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion liquid is dispersed by penetrating a fine flow path under high pressure. During this dispersion, it is effective to adjust the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0183] Examples of a method for applying the coating liquid for forming the charge generating layer onto the undercoat layer (or onto the intermediate layer) include conventional methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0184] The thickness of the charge generating layer is set, for example, preferably in the range of 0.1 μm or more and 5.0 μm or less, and more preferably in the range of 0.2 μm or more and 2.0 μm or less.

[0185] [Charge transport layer] The charge transport layer contains a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B), and a charge transport material. The charge transport layer may further contain a binder resin other than the polyester resin (1).

[0186] Details of the polyester resin (1) are as described above.

[0187] Examples of the charge transport material include electron transporting compounds such as quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and ethylene compounds. Examples of the charge transport material include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination, but are not limited to these.

[0188] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable.

[0189] [ka]

[0190] In structural formula (a-1), Ar T1 , Ar T2 , and Ar T3 each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -CH-CH=CH-CH=C(R T7 )(R T8 ) is shown. T4 , R T5 , R T6 , R T7 , and R T8 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Examples of the substituent for each of the above groups include a halogen atom, an alkyl group having from 1 to 5 carbon atoms, and an alkoxy group having from 1 to 5 carbon atoms. Examples of the substituent for each of the above groups also include a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0191] [ka]

[0192] In structural formula (a-2), R T91 and R T92 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 each independently represents a halogen atom, an alkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, an amino group substituted with an alkyl group having from 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) and R T12 , R T13 , R T14 , R T15 and R T16 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less. Examples of the substituent for each of the above groups include a halogen atom, an alkyl group having from 1 to 5 carbon atoms, and an alkoxy group having from 1 to 5 carbon atoms. Examples of the substituent for each of the above groups also include a substituted amino group substituted with an alkyl group having from 1 to 3 carbon atoms.

[0193] Among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7)(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 ) is preferable from the viewpoint of charge mobility.

[0194] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester polymer charge transport materials are particularly preferred. The polymer charge transport material may be used alone or in combination with a binder resin.

[0195] The charge transport material or polymer charge transport material may be a polycyclic aromatic compound, a heterocyclic compound, a hydrazone compound, a styryl compound, an enamine compound, a benzidine compound, a triaryl compound, or a cyclohexane compound. Also included are amine compounds, diamine compounds, oxadiazole compounds, carbazole compounds, organic polysilane compounds, pyrazoline compounds, indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, triazole compounds, and resins having groups derived from these substances. Specifically, the compounds described in paragraphs 0078 to 0080 of JP 2021-117377 A, paragraphs 0046 to 0048 of JP 2019-035900 A, paragraphs 0052 to 0053 of JP 2019-012141 A, paragraphs 0122 to 0134 of JP 2021-071565 A, paragraphs 0101 to 0110 of JP 2021-015223 A, and paragraph 0116 of JP 2013-097300 A can be mentioned.

[0196] The content of the charge transport material in the charge transport layer is preferably 28% by weight or more and 55% by weight or less based on the total solid content.

[0197] The charge transport layer contains at least a polyester resin (1) as a binder resin. The proportion of the polyester resin (1) in the total amount of the binder resin contained in the charge transport layer is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

[0198] The charge transport layer may contain a binder resin other than the polyester resin (1). Examples of the binder resin include polyester resins other than the polyester resin (1), polycarbonate resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl acetate resins, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, silicone resins, silicone alkyd resins, phenol-formaldehyde resins, styrene-alkyd resins, poly-N-vinylcarbazole, polysilanes, etc. These binder resins may be used alone or in combination of two or more.

[0199] The charge transport layer may contain other known additives, such as an antioxidant, a leveling agent, a defoaming agent, a filler, and a viscosity modifier.

[0200] The formation of the charge transport layer is not particularly limited, and a known formation method can be used. For example, the charge transport layer can be formed by forming a coating film of a coating liquid for forming the charge transport layer in which the above components are added to a solvent, drying the coating film, and heating it as necessary.

[0201] Examples of solvents for preparing the coating liquid for forming the charge transport layer include ordinary organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene, ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride, and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents may be used alone or in combination of two or more.

[0202] Examples of a coating method for coating the coating liquid for forming the charge transport layer on the charge generating layer include ordinary methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating and curtain coating.

[0203] The average thickness of the charge transport layer is preferably from 10 μm to 50 μm, more preferably from 15 μm to 45 μm, and even more preferably from 20 μm to 40 μm.

[0204] [Surface protective layer] The surface protective layer is a cured film of a composition containing a curing agent having at least one of a guanamine compound and a melamine compound, and at least one reactive group-containing charge transport material having at least one substituent selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH. The composition may contain other materials in addition to the curing agent and the reactive group-containing charge transport material.

[0205] [Reactive Group-Containing Charge Transport Material] The reactive group-containing charge transport material has at least one substituent selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH, and preferably has at least one of -OH and -OCH3. The surface protective layer formed using a reactive group-containing charge transport material having -OH as a substituent has low affinity with the charge transport layer in an unreacted state, but tends to have high affinity with the charge transport layer after reaction. As a result, the affinity between the surface protective layer and the charge transport layer increases as the reaction of the surface protective layer progresses. As a result, charge injection becomes easier, adhesion is improved, and peeling and lifting of the surface protective layer from the charge transport layer is more suppressed. The reactive group-containing charge transport material may be used alone or in combination of two or more kinds.

[0206] The reactive group-containing charge transport material is preferably a compound represented by the following general formula (I).

[0207] F-((-R 13 -X) n1 (R 14 ) n2 -Y) n3 (I)

[0208] In the general formula (I), F is an organic group derived from a compound having a hole transporting ability, R 13 and R 14 each independently represents a linear or branched alkylene group having 1 to 5 carbon atoms, n1 represents 0 or 1, n2 represents 0 or 1, and n3 represents an integer of 1 to 4. X represents an oxygen, NH, or sulfur atom, and Y represents -OH, -OCH3, -NH2, -SH, or -COOH. In the general formula (I), the compound having a hole transporting ability in the organic group derived from the compound having a hole transporting ability represented by F is preferably an arylamine derivative. As the arylamine derivative, preferably, a triphenylamine derivative and a tetraphenylbenzidine derivative are exemplified. The compound represented by general formula (I) is preferably a compound represented by the following general formula (II): The compound represented by general formula (II) is particularly excellent in charge mobility, stability against oxidation, etc.

[0209] [ka]

[0210] In general formula (II), Ar 1 From Ar 4 may be the same or different and each independently represents a substituted or unsubstituted aryl group; Ar 5 represents a substituted or unsubstituted aryl group or a substituted or unsubstituted arylene group, and D represents -(-R 13 -X) n1 (R 14 ) n2 -Y, c is independently 0 or 1, k is 0 or 1, and the total number of D is 1 or more and 4 or less. 13 and R 14each independently represents a linear or branched alkylene group having 1 to 5 carbon atoms, n1 represents 0 or 1, n2 represents 0 or 1, X represents an oxygen, NH, or sulfur atom, and Y represents -OH, -OCH3, -NH2, -SH, or -COOH. In the general formula (II), "-(-R 13 -X) n1 (R 14 ) n2 -Y" is the same as in general formula (I), R 13 and R 14 are each independently a linear or branched alkylene group having 1 to 5 carbon atoms. Furthermore, n1 is preferably 1. Furthermore, n2 is preferably 1. Furthermore, X is preferably oxygen. Furthermore, Y is preferably at least one of -OH and -OCH3. The total number of Ds in general formula (II) corresponds to n3 in general formula (I) and is preferably 2 or more and 4 or less, and more preferably 3 or more and 4 or less. In general formula (I) or (II), when the total number of Ds in one molecule is 2 to 4, preferably 3 to 4, the crosslinking density increases, making it easier to obtain a crosslinked membrane with higher strength.

[0211] In the general formula (II), Ar1 to Ar4 are preferably any one of the following formulas (1) to (7). In addition, the following formulas (1) to (7) each include "-(D)" which can be linked to each of Ar1 to Ar4. C " is shown.

[0212] [ka]

[0213] In equations (1) to (7), R 15 represents one member selected from the group consisting of a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, a phenyl group substituted with an alkyl group having from 1 to 4 carbon atoms or an alkoxy group having from 1 to 4 carbon atoms, an unsubstituted phenyl group, and an aralkyl group having from 7 to 10 carbon atoms; R 16 From R 18each represents one member selected from the group consisting of a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having from 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having from 7 to 10 carbon atoms, and a halogen atom; Ar represents a substituted or unsubstituted arylene group; D and c are the same as “D” and “c” in general formula (II); s each represents 0 or 1; and t represents an integer of 1 to 3.

[0214] Ar in the formula (7) is preferably represented by the following formula (8) or (9).

[0215] [ka]

[0216] In equations (8) to (9), R 19 and R 20 each represents one member selected from the group consisting of a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having from 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having from 7 to 10 carbon atoms, and a halogen atom, and t represents an integer of 1 to 3.

[0217] Z' in formula (7) is preferably represented by any one of the following formulas (10) to (17).

[0218] [ka]

[0219] In equations (10) to (17), R 21 and R 22 each represents one selected from the group consisting of a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms or a phenyl group substituted with an alkoxy group having from 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having from 7 to 10 carbon atoms, and a halogen atom; W represents a divalent group; q and Each r represents an integer of 1 or more and 10 or less, and each t represents an integer of 1 or more and 3 or less.

[0220] W in the formulae (16) to (17) is preferably any one of the divalent groups represented by the following (18) to (26), where u in the formula (25) represents an integer of 0 to 3.

[0221] [ka]

[0222] In general formula (II), Ar 5 When k is 0, Ar 1 From Ar 4 When k is 1, it is an arylene group formed by removing a hydrogen atom from any of the aryl groups (1) to (7).

[0223] Specific examples of the compound represented by formula (I) are shown below, but the compound represented by formula (I) is not limited to these in any way.

[0224] [ka]

[0225] [ka]

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] [ka]

[0230] [ka]

[0231] The total content of the specific charge transporting material (solid content concentration in the coating liquid) is preferably 90% by mass or more, more preferably 94% by mass or more. When the solid content concentration is 90% by mass or more, the deterioration of electrical properties is suppressed.

[0232] [Hardening agent] The curing agent has at least one of a guanamine compound and a melamine compound. The curing agent may be used alone or in combination of two or more. In this specification, the guanamine compound refers to a compound having a guanamine structure, and the melamine compound refers to a compound having a melamine structure. A cured film of a composition containing at least one compound selected from a guanamine compound and a melamine compound as a curing agent undergoes a crosslinking reaction with a charge transport agent, thereby reducing unreacted groups in the cured film and making the interface hydrophobic. As a result, it is believed that the interface has excellent adhesion due to strong affinity and interaction with the hydrophobic charge transport layer containing the above-mentioned polyester resin (1).

[0233] (Guanamine compounds) The guanamine compound is a compound having a guanamine skeleton (structure), and examples thereof include acetoguanamine, benzoguanamine, formoguanamine, steroguanamine, spiroguanamine, and cyclohexylguanamine. The guanamine compound is preferably at least one of the compounds represented by the following general formula (A) and their multimers. Here, the multimer is an oligomer polymerized with the compound represented by the general formula (A) as a structural unit, and has a degree of polymerization of, for example, 2 to 200 (preferably 2 to 100). The compound represented by the general formula (A) may be used alone or in combination of two or more. In particular, when the compound represented by the general formula (A) is used in combination of two or more, or as a multimer (oligomer) having the compound represented by the general formula (A) as a structural unit, the solubility in a solvent is improved.

[0234] [ka]

[0235] In the general formula (A), R1 represents a linear or branched alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 4 to 10 carbon atoms. R2 to R5 each independently represent a hydrogen atom. , -CH2-OH, or -CH2-O-R6, where R6 represents a linear or branched alkyl group having 1 to 10 carbon atoms. In the general formula (A), the alkyl group represented by R1 has a carbon number of 1 to 10, preferably 1 to 8 and more preferably 1 to 5. The alkyl group may be linear or branched. In the general formula (A), the phenyl group represented by R1 has a carbon number of 6 or more and 10 or less, more preferably 6 or more and 8 or less. Examples of the substituent substituted on the phenyl group include a methyl group, an ethyl group, and a propyl group. In the general formula (A), the alicyclic hydrocarbon group represented by R1 has a carbon number of 4 to 10, more preferably 5 to 8. Examples of the substituent substituted on the alicyclic hydrocarbon group include a methyl group, an ethyl group, and a propyl group. In the general formula (A), in "-CH2-O-R6" representing R2 to R5, the alkyl group representing R6 has a carbon number of 1 to 10, preferably 1 to 8 or more, and more preferably 1 to 6. The alkyl group may be linear or branched. Preferred examples include a methyl group, an ethyl group, and a butyl group.

[0236] Particularly preferred compounds represented by general formula (A) are those in which R1 represents a substituted or unsubstituted phenyl group having 6 to 10 carbon atoms, and R2 to R5 each independently represent -CH2-O-R6. R6 is preferably selected from a methyl group or an n-butyl group. The compound represented by the general formula (A) can be synthesized, for example, using guanamine and formaldehyde by a known method (for example, Jikken Kagaku Koza, 4th ed., Vol. 28, p. 430, edited by the Chemical Society of Japan). Below, exemplary compounds (A)-1 to (A)-42 are shown as specific examples of the compound represented by general formula (A), but the present embodiment is not limited to these. In addition, the following specific examples are monomers, but may be polymers (oligomers) having these monomers as structural units. In the following exemplary compounds, "Me" represents a methyl group, "Bu" represents a butyl group, and "Ph" represents a phenyl group.

[0237] [ka]

[0238] [ka]

[0239] [ka]

[0240] [ka]

[0241] In addition, examples of commercially available products of the compound represented by general formula (A) include Super Beckamine(R) L-148-55, Super Beckamine(R) 13-535, Super Beckamine(R) L-145-60, Super Beckamine(R) TD-126 (all manufactured by Dainippon Ink Co., Ltd.), Nikalac BL-60, and Nikalac BX-4000 (all manufactured by Nippon Carbide Corporation). After synthesis or after purchasing a commercially available product, the compound represented by general formula (A) (including polymers) may be dissolved in a suitable solvent such as toluene, xylene, ethyl acetate, etc., and washed with distilled water, ion-exchanged water, etc., or may be treated with an ion-exchange resin to remove the influence of residual catalyst.

[0242] (Melamine compounds) The melamine compound has a melamine skeleton (structure), and is preferably at least one of the compounds represented by the following general formula (B) and their multimers. Here, the multimer is an oligomer polymerized with the compound represented by the general formula (B) as a structural unit, similar to the general formula (A), and has a degree of polymerization of, for example, 2 to 200 (preferably 2 to 100). The compound represented by the general formula (B) or its multimer may be used alone or in combination of two or more. It may also be used in combination with the compound represented by the general formula (A) or its multimer. In particular, when the compound represented by the general formula (B) is used in a mixture of two or more or as a multimer (oligomer) having the compound represented by the general formula (B) as a structural unit, the solubility in a solvent is improved.

[0243] [ka]

[0244] In general formula (B), R 6 From R 11 are each independently a hydrogen atom, -CH2-OH, -CH2-OR 12 , -OR 12 R 12represents an alkyl group having 1 to 5 carbon atoms which may be branched. Examples of the alkyl group include a methyl group, an ethyl group, and a butyl group. The compound represented by the general formula (B) is synthesized, for example, by a known method using melamine and formaldehyde (for example, synthesized in the same manner as the melamine resin described in Experimental Chemistry Lectures, 4th Edition, Vol. 28, p. 430). As specific examples of the compound represented by the general formula (B), the following exemplary compounds (B)-1 to (B)-8 are shown below, but the present embodiment is not limited thereto. The following specific examples are monomers, but may be polymers (oligomers) having these as structural units.

[0245] [ka]

[0246] Examples of commercially available products of the compound represented by general formula (B) include Super Melami No. 90 (manufactured by Nippon Oil & Fats Co., Ltd.), Super Beckamin® TD-139-60 (manufactured by Dainippon Ink Co., Ltd.), U-Ban 2020 (manufactured by Mitsui Chemicals, Inc.), Sumitex Resin M-3 (manufactured by Sumitomo Chemical Co., Ltd.), and Nikalac MW-30 (manufactured by Nippon Carbide Corporation). Furthermore, after synthesis or after purchasing a commercially available product, the compound represented by general formula (B) (including polymers) may be dissolved in a suitable solvent such as toluene, xylene, ethyl acetate, etc., and washed with distilled water, ion-exchanged water, etc., or may be treated with an ion-exchange resin to remove the influence of residual catalyst.

[0247] The curing agent may further contain other curing agents other than the guanamine compound and the melamine compound within a range in which the effects according to the present embodiment are achieved. Examples of other curing agents include an isocyanate compound and a polyol.

[0248] The proportion of the guanamine compound and the melamine compound in the entire curing agent is preferably 80% by mass or more, more preferably 85% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less.

[0249] The surface protective layer may contain other known additives, such as an antioxidant and a curing catalyst. The additive preferably contains, for example, an antioxidant. When the electrophotographic photoreceptor has a long life due to the increased mechanical strength of the surface thereof, the electrophotographic photoreceptor is in contact with an oxidizing gas for a long time, and therefore has a stronger oxidation resistance than before. In this respect, when an antioxidant is contained, deterioration caused by oxidizing gas such as ozone generated in a charging device is easily prevented. The antioxidant is preferably a hindered phenol-based or hindered amine-based antioxidant, and examples thereof include known antioxidants such as organic sulfur-based antioxidants, phosphite-based antioxidants, dithiocarbamate-based antioxidants, thiourea-based antioxidants, benzimidazole-based antioxidants, etc. The amount of antioxidant added is preferably 20% by mass or less, more preferably 10% by mass or less.

[0250] The additives may include, for example, a curing catalyst. The curing catalyst is preferably an acid-based curing catalyst. Examples of the acid-based catalyst include aliphatic carboxylic acids such as acetic acid, chloroacetic acid, trichloroacetic acid, trifluoroacetic acid, oxalic acid, maleic acid, malonic acid, and lactic acid, aromatic carboxylic acids such as benzoic acid, phthalic acid, terephthalic acid, and trimellitic acid, and aliphatic or aromatic sulfonic acids such as methanesulfonic acid, dodecylsulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, and naphthalenesulfonic acid.

[0251] The formation of the surface protection layer is not particularly limited, and a well-known formation method can be used. For example, the surface protection layer can be formed by forming a coating film of a coating liquid for forming the surface protection layer in which the above components are added to a solvent, drying the coating film, and, if necessary, subjecting it to a curing treatment such as heating.

[0252] Examples of solvents for preparing a coating liquid for forming a surface protective layer include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as tetrahydrofuran and dioxane, cellosolve solvents such as ethylene glycol monomethyl ether, and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more. The coating liquid for forming the surface protective layer may be a solvent-free coating liquid.

[0253] Examples of a method for applying the coating liquid for forming a surface protective layer onto a photosensitive layer (e.g., a charge transport layer) include conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. The coating liquid for forming the surface protective layer according to the present embodiment has a high polarity of the reactive group, so that when it is applied onto a photosensitive layer (e.g., a charge transport layer), it has a high surface tension and is prone to aggregation, which tends to cause coating unevenness. Therefore, in general, a small amount of a leveling agent such as a fluorine compound or a silicone compound may be added to the coating liquid in order to lower the surface tension, thereby improving wettability. As a result, after application, the leveling agent with low surface tension migrates (bleeds) to the vicinity of the surface with the volatilization of the solvent, making it easier to maintain a more uniform coating surface.

[0254] The thickness of the surface protective layer is, for example, preferably from 1 μm to 20 μm, and more preferably from 2 μm to 10 μm.

[0255] <Image forming apparatus, process cartridge> The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging unit for charging the surface of the electrophotographic photoreceptor, an electrostatic latent image forming unit for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing unit for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image, and a transfer unit for transferring the toner image to the surface of a recording medium. The electrophotographic photoreceptor according to the present embodiment is applied as the electrophotographic photoreceptor.

[0256] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as an apparatus provided with a fixing means for fixing a toner image transferred onto the surface of a recording medium; an apparatus of a direct transfer type for directly transferring a toner image formed on the surface of an electrophotographic photosensitive member onto a recording medium; an apparatus of an intermediate transfer type for primarily transferring a toner image formed on the surface of an electrophotographic photosensitive member onto the surface of an intermediate transfer member, and then secondarily transferring the toner image transferred onto the surface of the intermediate transfer member onto the surface of a recording medium; an apparatus provided with a cleaning means for cleaning the surface of an electrophotographic photosensitive member before charging after the transfer of a toner image; an apparatus provided with a discharging means for irradiating the surface of an electrophotographic photosensitive member with discharging light before charging after the transfer of a toner image, thereby discharging the toner image; and an apparatus provided with an electrophotographic photosensitive member heating member for increasing the temperature of the electrophotographic photosensitive member and reducing the relative temperature.

[0257] In the case of an intermediate transfer type device, the transfer means has, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the electrophotographic photosensitive body onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

[0258] The image forming apparatus according to the present embodiment is an image forming apparatus of a dry development type, a wet development type (liquid The image forming apparatus may be of either a developing method using a developer or a developing method using a developing agent.

[0259] In the image forming apparatus according to the present embodiment, for example, a portion including an electrophotographic photosensitive member may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photosensitive member according to the present embodiment is preferably used. The process cartridge may include, in addition to the electrophotographic photosensitive member, at least one selected from the group consisting of a charging means, an electrostatic latent image forming means, a developing means, and a transfer means.

[0260] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Principal parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0261] FIG. 2 is a schematic diagram showing an example of the image forming apparatus according to the present embodiment. As shown in FIG. 2, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming means), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is disposed at a position where it can expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, the transfer device 40 is disposed at a position facing the electrophotographic photoreceptor 7 via the intermediate transfer body 50, and the intermediate transfer body 50 is disposed with a part of it in contact with the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer means.

[0262] 2 supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging means), a developing device 11 (an example of a developing means), and a cleaning device 13 (an example of a cleaning means) integrally within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is disposed so as to come into contact with the surface of the electrophotographic photoreceptor 7. The cleaning member may not be in the form of the cleaning blade 131, but may be a conductive or insulating fibrous member, which may be used alone or in combination with the cleaning blade 131.

[0263] FIG. 2 shows an example of an image forming apparatus equipped with a fibrous member 132 (roll-shaped) that supplies lubricant 14 to the surface of electrophotographic photosensitive member 7, and a fibrous member 133 (flat brush-shaped) that assists in cleaning, which are arranged as needed.

[0264] Hereinafter, each configuration of the image forming apparatus according to this embodiment will be described.

[0265] -Charging device- As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, charging brush, charging film, charging rubber blade, charging tube, etc. Also, a non-contact type roller charger, a scorotron charger or corotron charger that utilizes corona discharge, or other chargers known per se, can be used.

[0266] -Exposure equipment- The exposure device 9 may be, for example, an optical device that exposes the surface of the electrophotographic photoreceptor 7 to light such as semiconductor laser light, LED light, or liquid crystal shutter light in a predetermined image. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. The mainstream wavelength of the semiconductor laser is near infrared with an oscillation wavelength of about 780 nm. However, it is not limited to this wavelength, and a laser with an oscillation wavelength of 600 nm or a blue laser with an oscillation wavelength of 400 nm or more and 450 nm or less may also be used. In addition, a multi-beam is output for color image formation. A surface-emitting laser light source capable of obtaining a high-resolution image is also effective.

[0267] -Developing device- The developing device 11 may be, for example, a general developing device that develops by contacting or non-contacting a developer. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and may be selected according to the purpose. For example, it may be a known developing device that has a function of attaching a one-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, roller, or the like. Among them, it is preferable to use a developing roller that holds a developer on its surface.

[0268] The developer used in the developing device 11 may be a one-component developer containing only toner, or may be a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. Known developers are used.

[0269] -Cleaning device- The cleaning device 13 is a cleaning blade type device equipped with a cleaning blade 131. In addition to the cleaning blade type, a fur brush cleaning type or a simultaneous development and cleaning type may also be adopted.

[0270] -Transfer device- Examples of the transfer device 40 include known transfer chargers such as a contact type transfer charger using a belt, roller, film, rubber blade, etc., and a scorotron transfer charger or corotron transfer charger that utilizes corona discharge.

[0271] -Intermediate transfer body- A belt-like intermediate transfer belt containing semiconductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. is used as the intermediate transfer body 50. The intermediate transfer body may be in the form of a drum other than a belt.

[0272] FIG. 3 is a schematic diagram showing another example of the image forming apparatus according to the present embodiment. 3 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one electrophotographic photosensitive body is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem type. EXAMPLES

[0273] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are based on mass.

[0274] In the following description, syntheses, treatments, manufactures, etc. were carried out at room temperature (25° C.±3° C.) unless otherwise specified.

[0275] <Production of polyester resin (1)> [Polyester resin (1-1)] In a reaction vessel equipped with a stirring device, 12.6373 g of 4,4'-(4-methylpentane-2,2-diyl)diphenol, 0.1233 g of 4-t-butylphenol, 0.0632 g of sodium hydrosulfite, and 240 mL of water were placed to prepare a suspension. This suspension was stirred at a temperature of 20°C and then added with 4.8392 g of sodium hydroxide and 2.0 mL of benzyltributylammonium chloride. 0.1981g and 160mL of water were added and stirred for 30 minutes under a nitrogen atmosphere. 220mL of o-dichlorobenzene was added to this aqueous solution and stirred for 30 minutes under a nitrogen atmosphere, and then 12.0000g of 4,4'-biphenyl dicarbonyl chloride was added as powder. After the addition was completed, the reaction was allowed to proceed at a temperature of 20°C and stirred for 4 hours under a nitrogen atmosphere. The solution after polymerization was diluted with 300mL of o-dichlorobenzene and the aqueous layer was removed. After washing with a dilute acetic acid solution and ion-exchanged water, the polymer was precipitated by pouring into methanol. The precipitated polymer was filtered off and dried at 50°C. The polymer was redissolved in 900mL of tetrahydrofuran and poured into methanol to precipitate the polymer. The precipitated polymer was filtered off, washed with methanol, and dried at 50°C to obtain 17.5g of a white polymer. The weight average molecular weight measured by GPC (gel permeation chromatography) was 105000. The measurement was carried out using tetrahydrofuran as an eluent, and the molecular weight of the polymer was determined as a polystyrene-equivalent molecular weight.

[0276] [Polyester resins (1-2) to (1-8)] The polyester resins were synthesized in the same manner as in the production process of polyester resin (1-1), except that the monomer species used were changed. The monomer species of the polyester resins are shown in Table 1.

[0277] <Example 1> - Formation of undercoat layer - As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 250 mm, and a wall thickness of 1 mm was prepared.

[0278] Zinc oxide (average particle size 70 nm, specific surface area 15 m 2 100 parts of a silane coupling agent (trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) was added to the mixture and stirred for 2 hours. The toluene was then distilled off under reduced pressure, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0279] 110 parts of the surface-treated zinc oxide was mixed with 500 parts of tetrahydrofuran by stirring, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added thereto, followed by stirring for 5 hours at 50° C. Thereafter, the solid content was filtered off by reduced pressure filtration and dried under reduced pressure at 60° C. to obtain zinc oxide with alizarin added thereto.

[0280] 100 parts of a solution of 60 parts of alizarin-added zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, product name: Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), and 15 parts of butyral resin (product name: S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) dissolved in 68 parts of methyl ethyl ketone was mixed with 5 parts of methyl ethyl ketone, and the mixture was stirred using 1 mm diameter glass beads. The mixture was dispersed in a sand mill for 2 hours to obtain a dispersion. 0.005 parts of dioctyltin dilaurate as a catalyst and 4 parts of silicone resin particles (product name: Tospearl 145, manufactured by Momentive Performance Materials) were added to the dispersion to obtain a coating liquid for forming an undercoat layer. The coating liquid for forming an undercoat layer was applied to the outer peripheral surface of the conductive substrate by a dip coating method, and dried and cured at 170°C for 40 minutes to form an undercoat layer. The average thickness of the undercoat layer was 25 μm.

[0281] - Formation of charge generation layer - A mixture of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in the X-ray diffraction spectrum using Cukα characteristic X-rays) as a charge generating material, 10 parts of vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using glass beads with a diameter of 1 mm for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming a charge generating layer. The coating solution for forming a charge generating layer was dip-coated on the undercoat layer and dried at room temperature (25°C±3°C) to form a charge generating layer with an average thickness of 0.18 μm.

[0282] - Formation of charge transport layer - 55 parts of polyester resin (1-1) as a binder resin and 40 parts of CTM-1 as a charge transport material were dissolved in 270 parts of tetrahydrofuran and 30 parts of toluene to obtain a coating liquid for forming a charge transport layer. The coating liquid for forming a charge transport layer was dip-coated on the charge generation layer and dried at 145°C for 30 minutes to form a charge transport layer. The average thickness of the charge transport layer was 24 μm.

[0283] [ka]

[0284] - Formation of a surface protection layer - 10 parts by mass of the charge transport material (I-25), 10 parts by mass of (I-8), 2 parts by mass of (I-26), 1 part by mass of (I-27), and 0.5 parts by mass of methoxymethylated melamine ((B)-2) were added to a mixed solvent of 35 parts by mass of isopropanol and 20 parts by mass of n-butanol, and the mixture was stirred and dissolved at 50° C. for 2 hours. After cooling to room temperature, 0.1 parts by mass of curing catalyst Nacure 2500 (King Industries Co., Ltd.) was added to obtain a coating liquid for forming a surface protective layer. The coating liquid for forming a surface protective layer was applied by dip coating on the charge transport layer, and the coating liquid was dried to the touch at 25° C. for 10 minutes, and then dried and cured at 150° C. for 60 minutes to obtain an electrophotographic photoreceptor.

[0285] <Examples 2 to 17> Each photoreceptor was prepared in the same manner as in Example 1, except that in forming the charge transport layer, the type and amount of polyester resin (1-1) and the curing agent for the surface protective layer were changed to those shown in Table 1.

[0286] <Comparative Example 1 to Comparative Example 2> Each photoreceptor was prepared in the same manner as in Example 1, except that in forming the charge transport layer, the resin shown in the table was used instead of the polyester resin (1-1). The details of the resin used instead of the polyester resin are as follows. Polycarbonate resin Z: (Teijin Chemical Co., Ltd.) [ka] Polycarbonate resin BPZ: (Teijin Chemical Co., Ltd.) [ka]

[0287] <Comparative Example 3> A photoreceptor was prepared in the same manner as in Example 1, except that in forming the surface protective layer, the hardener was changed to "phenol resin PL-2243 (manufactured by Gun-ei Chemical Industry Co., Ltd.)" instead of "methoxymethylated melamine ((B)-2)".

[0288] <Evaluation> The electrophotographic photoreceptor of each example was mounted on an image forming apparatus, Color 1000i Press, manufactured by FUJIFILM Business Innovation Co., Ltd., and the following evaluations were carried out using this.

[0289] (Image quality evaluation) An image output test of 100,000 sheets was carried out at 20% halftone in an environment of 28°C temperature and 85% relative humidity. The image quality of the 100,000th sheet obtained was evaluated using the following indexes. Note that this evaluation was performed under an environment where the surface protective layer provided on the electrophotographic photoreceptor of each example was in a thin state of 2 μm in thickness and peeling or lifting of the surface protective layer is likely to occur. The results are shown in the table below. A: No unevenness in density at all, no problem. B: Density unevenness occurs, but at a level that does not cause practical problems C: Peeling causes streaky uneven density and is problematic.

[0290] (Adhesion evaluation) After the above image quality evaluation, the surface of the photoreceptor was visually observed, and peeling and lifting of the surface protective layer of the electrophotographic photoreceptor were evaluated according to the following criteria. The results are shown in the table below. A: No peeling at all, no problem. B: Very small partial discoloration can be seen, but no peeling can be seen, so it is not a problem. C: Stripes of peeling were visible to the naked eye and were at a problematic level.

[0291] [Table 1]

[0292] As shown in Table 1, it was found that the electrophotographic photoreceptors of the examples suppressed peeling and lifting of the surface protective layer from the charge transport layer, even when the surface protective layer was thinned to 2 μm, compared to the electrophotographic photoreceptors of the comparative examples.

[0293] Specific means for solving the problem of this embodiment include the following aspects. (((1))) A conductive substrate; an undercoat layer provided on the conductive substrate; a charge generating layer provided on the undercoat layer; a charge transport layer provided on the charge generating layer, the charge transport layer comprising a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B), and a charge transport material; a surface protective layer provided on the charge transport layer, the surface protective layer containing at least one of a guanamine compound and a melamine compound curing agent, and at least one reactive group-containing charge transport material having at least one substituent selected from the group consisting of -OH, -OCH3, -NH2, -SH, and -COOH; An electrophotographic photoreceptor comprising: [ka] (In the above formula (A), n 1 is 1, 2 or 3, and n 1 m 1 are each independently 0, 1, 2, 3 or 4; m 1 Ra 1 each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In the formula (B), Rb 1and Rb 2 each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb 3 , Rb 4 , Rb 5 , Rb 6 , Rb 7 , Rb 8 , Rb 9 and Rb 10 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; Rb 1 and Rb 2 may be bonded to form a cyclic alkyl group. (((2))) The surface free energy E OCL and the surface free energy E in the charge transport layer. CT The difference between OCL -E CT ) is 6 mN / m or more and 10 mN / m or less. (((3))) The surface protection layer has a surface free energy E OCL The electrophotographic photoreceptor according to (((2))) above, wherein the surface tension is 38 mN / m or more and 42 mN / m or less. (((4))) The charge transport layer has a surface free energy E CT The electrophotographic photoreceptor according to (((2))) or (((3))), wherein the surface tension is 32 mN / m or more and 35 mN / m or less. (((5))) The electrophotographic photoreceptor according to any one of (((1))) to (((4))), wherein the reactive group-containing charge transport material has —OH as the substituent. (((6))) The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein the content of the polyester resin (1) is 35% by mass or more and 65% by mass or less, based on the total solid content of the charge transport layer. (((7))) An electrophotographic photoreceptor according to any one of (((1))) to (((6))), A process cartridge that is detachably attached to an image forming apparatus. (((8))) The electrophotographic photoreceptor according to any one of (((1))) to (((6))) above; a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; The electrostatic latent image formed on the surface of the electrophotographic photoreceptor is developed with a developer containing a toner. a developing device for forming a toner image by using the toner; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

[0294] According to the invention related to (((1))) or (((5))), there is provided a laminated electrophotographic photoreceptor having a surface protective layer, which is capable of suppressing peeling and floating of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner, as compared with a case in which the charge transport layer does not contain the polyester resin (1) but contains a polycarbonate resin. According to the invention related to (((2))), in a laminated electrophotographic photoreceptor having a surface protective layer, the surface free energy E OCL and the surface free energy E in the charge transport layer. CT The difference between OCL -E CT ) is less than 6 mN / m or more than 10 mN / m, an electrophotographic photoreceptor is provided which suppresses peeling and lifting of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. According to the invention related to (((3))), in a laminated electrophotographic photoreceptor having a surface protective layer, the surface protective layer has a surface free energy E OCL In comparison with the case where the surface protective layer has a surface tension of less than 38 mN / m or more than 42 mN / m, an electrophotographic photoreceptor is provided which suppresses peeling and lifting of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. According to the invention related to (((4))), in the laminated electrophotographic photoreceptor having a surface protective layer, the charge transport layer has a surface free energy E CTIn comparison with the case where the surface protective layer has a thickness of less than 32 mN / m or more than 35 mN / m, an electrophotographic photoreceptor is provided which suppresses peeling and lifting of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. According to the invention related to (((6))), there is provided an electrophotographic photoreceptor which is capable of suppressing peeling and floating of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner, compared with a case in which the content of the polyester resin (1) is less than 35 mass % or more than 65 mass % relative to the total solid content of the charge transport layer, in a laminated electrophotographic photoreceptor having a surface protective layer. According to the invention related to (((7))) or (((8))), there is provided a process cartridge or image forming apparatus including an electrophotographic photoreceptor in which the charge transport layer does not contain the polyester resin (1) and instead contains a polycarbonate resin, and which suppresses peeling and floating of the surface protective layer from the charge transport layer even when the surface protective layer is made thinner. [Explanation of symbols]

[0295] 107A Electrophotographic photoreceptor, 101 Undercoat layer, 102 Charge generation layer, 103 Charge transport layer, 104 Conductive substrate, 105 Photosensitive layer, 106 Surface protective layer

[0296] 7 electrophotographic photoreceptor, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device A cleaning device, 14 lubricant, 40 transfer device, 50 intermediate transfer body, 100 image forming device, 120 image forming device, 131 cleaning blade, 132 fibrous member (roll type), 133 fibrous member (flat brush type), 300 process cartridge

Claims

1. A conductive substrate; an undercoat layer provided on the conductive substrate; a charge generating layer provided on the undercoat layer; a charge transport layer provided on the charge generating layer, the charge transport layer containing a polyester resin (1) having a dicarboxylic acid unit (A) represented by the following formula (A) and a diol unit (B) represented by the following formula (B), and a charge transport material; a curing agent having at least one of a guanamine compound and a melamine compound, and ３ , -NH ２ a surface protective layer which is a cured film of a composition containing at least one reactive group-containing charge transport material having at least one substituent selected from the group consisting of -SH and -COOH; An electrophotographic photoreceptor comprising: 【Chemistry 1】 In formula (A), n １ is 1, 2 or 3; n １ m １ are each independently 0, 1, 2, 3 or 4; m １ Ra １ each independently represents an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. In formula (B), Rb １ and Rb ２ each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; Rb ３ , Rb ４ , Rb ５ , Rb ６ , Rb ７ , Rb ８ , Rb ９ and Rb １０ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; Rb １ and Rb ２ may be bonded to form a cyclic alkyl group.

2. The surface free energy E ＯＣＬ and the surface free energy E in the charge transport layer. ＣＴ The difference between ＯＣＬ -E ＣＴ 2. The electrophotographic photoreceptor according to claim 1, wherein the surface tension is 6 mN / m or more and 10 mN / m or less.

3. The surface protection layer has a surface free energy E ＯＣＬ 3. The electrophotographic photoreceptor according to claim 2, wherein the surface tension is 38 mN / m or more and 42 mN / m or less.

4. The charge transport layer has a surface free energy E ＣＴ The electrophotographic photoreceptor according to claim 2, wherein the surface tension is 32 mN / m or more and 35 mN / m or less.

5. The reactive group-containing charge transport material has —OH and —OCH ３ The electrophotographic photoreceptor according to claim 1 , wherein the substituent is at least one of the following:

6. 2. The electrophotographic photoreceptor according to claim 1, wherein the content of the polyester resin (1) is 35% by mass or more and 65% by mass or less based on the total solid content of the charge transport layer.

7. The electrophotographic photoreceptor according to any one of claims 1 to 6 is provided, A process cartridge that is detachably attached to an image forming apparatus.

8. The electrophotographic photoreceptor according to any one of claims 1 to 6, a charging device for charging a surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; The electrostatic latent image formed on the surface of the electrophotographic photoreceptor is developed with a developer containing a toner. a developing device for forming a toner image by using the toner; a transfer device for transferring the toner image onto a surface of a recording medium; An image forming apparatus comprising:

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