JP2006284777A - Electrophotographic photoreceptor for wet development and image forming apparatus for wet development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor for wet development excellent in solvent resistance and sensitivity characteristics by using a combination of a specified binder resin and a hole transport agent having a specified molecular weight, and to provide an image forming apparatus for wet development equipped with the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor for wet development has a photosensitive layer containing a binder resin, a hole transport agent and a charge generating agent, and the image forming apparatus for wet development includes the photoreceptor; wherein the molecular weight of the hole transport agent is specified to ≥900, and the photoreceptor contains a polycarbonate resin expressed by general formula (1) as the binder resin. In general formula (1), each of R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>, R<SP>4</SP>, R<SP>5</SP>and R<SP>6</SP>independently represents a hydrogen atom, halogen atom, substituted or unsubstituted 1-12C alkyl group, or the like, and R<SP>7</SP>represents a hydrogen atom, or a substituted or unsubstituted 1-8C alkyl group or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer type wet developing electrophotographic photosensitive member and a wet developing image forming apparatus including the same, and more particularly to a multilayer type wet developing electrophotographic photosensitive member excellent in solvent resistance and sensitivity characteristics. The present invention relates to an image forming apparatus for wet development.

Conventionally, as an electrophotographic photoreceptor for wet development used in an image forming apparatus or the like, an organic material composed of an organic photoreceptor material such as a charge transport agent (a hole transport agent or an electron transport agent), a charge generator, and a binder resin. Photoconductors are widely used. Such organic photoreceptors are easier to manufacture and structure than conventional inorganic photoreceptors.
However, there has been a problem that conventional electrophotographic photoreceptors for wet development are easily eroded in a short time by a hydrocarbon solvent (liquid developer) called isopar.

  Therefore, the present applicant is an electrophotographic photoreceptor for wet development including a photoreceptor layer containing a binder resin, a charge transport agent, and a charge generator, and the binder resin has the following general formula ( The electrophotographic photosensitive member for wet development having excellent solvent resistance has already been proposed by using the polycarbonate resin having the repeating structural unit represented by 42). (For example, Patent Document 1)

(R ⁵⁸ and R ⁵⁹ in the general formula (42) may be the same or different and represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

  In addition, an electrophotographic photoreceptor using a polycarbonate resin having a structural unit represented by the general formulas (43) and (44), which can maintain electrophotographic characteristics excellent in abrasion resistance and scratch resistance for a long time. Is disclosed (for example, Patent Document 2).

(In the general formula (44), each R ⁶⁰ is independently a halogen atom or an optionally substituted alkyl group, alkoxy group, aryl group, aryl-substituted alkenyl group and condensed polycyclic hydrocarbon group. And f represents an integer of 0 to 4.)
JP 2002-116560 (Claims etc.) JP 2001-215739 A (Claims etc.)

  However, the electrophotographic photoreceptors for wet development described in Patent Document 1 and Patent Document 2 are hydrocarbons that are still insufficient in solvent resistance and used as a wet development electrophotographic photoreceptor for a long time. There was a problem that it was easily immersed in the system solvent (liquid developer) and the hole transport agent was easily eluted.

Therefore, the present inventors have used a specific polycarbonate resin as a binder resin and a hole transport agent having a specific molecular weight in a multilayer type wet development electrophotographic photosensitive member, and thereby charge transport over a long period of time. The present inventors have found the fact that the elution amount of the agent is remarkably reduced and that excellent sensitivity characteristics are maintained, and the present invention has been completed.
That is, an object of the present invention is to provide a multilayer wet-development electrophotographic photosensitive member excellent in solvent resistance and sensitivity characteristics for a long time and an image forming apparatus provided with such a multilayer wet-development electrophotographic photosensitive member. It is to provide.

  According to the present invention, there is provided a laminate type wet developing electrophotographic photosensitive member comprising a charge generation layer containing a charge generation agent and a charge transport layer containing a hole transport agent and a binder resin. The molecular weight of the hole transporting agent is 900 or more, and a laminate type wet developing electrophotographic photosensitive member containing a polycarbonate resin represented by the following general formula (1) as a binder resin is provided. The point can be solved.

(R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ in the general formula (1) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted carbon number of 1 to 12 An alkyl group, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl substituted alkenyl group having 6 to 30 carbon atoms, Alternatively, it is a substituted or unsubstituted condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, and R ⁷ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, a substituted or unsubstituted carbon number. 6-30 aryl groups or trifluoromethyl groups.)

Further, when constituting the electrophotographic photosensitive member for multilayer wet development of the present invention, it is preferable that R ⁵ and R ⁶ in the general formula (1) are hydrogen atoms.

  Further, in constituting the laminated type electrophotographic photoreceptor for wet development of the present invention, it is preferable that the hole transporting agent has a structure represented by the general formula (2) or (3).

(R ^{8 to} R ¹⁴ in the general formula (2) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number 1 to 1 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms, A substituted unsaturated hydrocarbon group represented by the general formula (4), a substituent represented by —OR ¹⁵ (R ¹⁵ is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 30 carbon atoms). Or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of R ^{8 to} R ^14. )

(R ^{16 to} R ²¹ in the general formula (3) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number 1 to 1 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms, substituted unsaturated hydrocarbon group represented by the general formula ^{(4), -OR 22 (R} 22 is an alkyl group or an aryl group having 6 to 30 carbon atoms, having 1 to 10 carbon atoms.) represented by substituted by Or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of R ^{16 to} R ^21. )

(R ²³ and R ²⁴ in the general formula (4) are each independently a hydrogen atom, a halogen atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon atom having 1 to 12 carbon atoms. A halogenated alkyl group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and the repeating number c is an integer of 0 to 2.)

  Further, in constituting the electrophotographic photoreceptor for multilayer wet development of the present invention, the hole transport agent preferably contains at least one compound represented by the following general formulas (5) to (8).

(Several R ^{25 to} R ³² in the general formula (5) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. A halogenated alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 12 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and X ₁ is a substituted or unsubstituted carbon number. An arylene group having 6 to 30 carbon atoms, an unsaturated hydrocarbon group having an aryl group having 6 to 30 carbon atoms, or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, wherein the repeating number d is an integer of 0 to 2 .)

(Several R ^{33 to} R ⁴⁰ in the general formula (6) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms , represented by substituted unsaturated hydrocarbon group represented by the general formula ^{(4), -OR 41 (R} 41 is an alkyl group or an aryl group having 6 to 30 carbon atoms, having 1 to 10 carbon atoms.) A substituent, or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of a plurality of R ^{33 to} R ^40. )

(Several R ^{42 to} R ⁴⁷ in the general formula (7) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms And a substituted unsaturated hydrocarbon group represented by the general formula (4), —OR ⁴⁸ (R ⁴⁸ is an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms). A substituted polycyclic hydrocarbon group formed by combining or condensing two or more of a plurality of R ^{42 to} R ⁴⁷ , and X ² is a substituted or unsubstituted arylene having 6 to 30 carbon atoms Group having an aryl group having 6 to 30 carbon atoms Hydrocarbon group, or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms.)

(Several R ^{49 to} R ⁵⁵ in the general formula (8) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms , substituted unsaturated hydrocarbon group represented by formula (4) or -OR ^56, (R ⁵⁶ is an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms.) are represented by Or a condensed polycyclic hydrocarbon group formed by combining or condensing two or more of a plurality of R ^{49 to} R ⁵⁵ , the repeating number e is an integer of 0 to 2, and X ³ is Substituted or unsubstituted arylene having 6 to 30 carbon atoms An unsaturated hydrocarbon group or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms.)

  Further, in constituting the electrophotographic photosensitive member for multilayer wet development according to the present invention, the addition amount of the hole transport agent is set to a value within the range of 10 to 80 parts by weight with respect to 100 parts by weight of the binder resin. It is preferable.

  Further, in constituting the electrophotographic photosensitive member for multilayer wet development of the present invention, it is preferable to contain titanyl phthalocyanine (Y type) as a charge generating agent.

In constructing the electrophotographic photoreceptor for multilayer wet development of the present invention, hole transport is carried out when immersed in a hydrocarbon solvent used as a developer for wet development at room temperature for 2000 hours. The elution amount of the agent is preferably 1 × 10 ⁻⁶ g / cm ³ or less.

  Another aspect of the present invention includes any one of the above-described laminated wet developing electrophotographic photosensitive members, and a charging step, an exposing step, and a developing step around the laminated wet developing electrophotographic photosensitive member. The image forming apparatus is a multi-layer type wet developing apparatus in which a part for carrying out the transfer process is arranged and an image is formed using a liquid developer in which a toner is dispersed in a hydrocarbon solvent in the developing process. .

  According to the multilayer electrophotographic photoreceptor for wet development of the present invention, a hydrocarbon solvent used as a developer for wet development by using a hole transport agent having a specific molecular weight and a specific binder resin in combination. In addition, even when immersed for a long time, it is possible to provide a multilayer electrophotographic photoreceptor for wet development that has a small elution amount of the hole transport agent and is excellent in sensitivity characteristics.

Moreover, according to the multilayer electrophotographic photoreceptor for wet development of the present invention, since R ⁵ and R ⁶ represented by the general formula (1) are hydrogen atoms, the compatibility with the hole transport agent is excellent. Therefore, an electrophotographic photosensitive member for wet development having excellent durability and sensitivity characteristics can be provided. Further, since the polycarbonate resin having such a structure is easy to manufacture, a laminated electrophotographic photosensitive member for wet development having excellent characteristics can be stably manufactured.

  Further, according to the multilayer electrophotographic photosensitive member for wet development of the present invention, a specific bond is obtained by using a compound having a structure represented by the general formula (2) or (3) as a hole transport agent. Excellent compatibility with the resin and high injection efficiency from the charge generating agent to the charge transporting agent, so that it is possible to provide a laminated electrophotographic photosensitive member for wet development having excellent durability and sensitivity characteristics. .

  In addition, according to the multilayer electrophotographic photoreceptor for wet development of the present invention, a specific bond is obtained by including at least one compound represented by the general formulas (5) to (8) as a hole transport agent. Provided is a multilayer electrophotographic photosensitive member for wet development that is more excellent in compatibility with a resin and further improves the durability and sensitivity characteristics because the injection efficiency from the charge generator to the charge transport agent is further increased. be able to.

  Further, according to the multilayer electrophotographic photosensitive member for wet development of the present invention, by limiting the addition amount of the hole transport agent to a predetermined range, crystallization of the hole transport agent can be effectively prevented, Furthermore, it is possible to provide a laminated electrophotographic photosensitive member for wet development which is excellent in sensitivity characteristics.

  Further, according to the multilayer electrophotographic photosensitive member for wet development of the present invention, a predetermined charge generating agent is used, so that predetermined sensitivity characteristics can be maintained for a long time even when a relatively small amount is added. Can do.

  In addition, according to the electrophotographic photoreceptor for wet development of the present invention, the solvent resistance can be accurately determined in a relatively short time (2000 hours) by limiting the elution amount of the hole transport agent under a predetermined condition. can do. For example, the solvent resistance in the case where 100,000 images are formed can be estimated by a 2000 hour immersion test.

  According to the image forming apparatus for wet development of the present invention, the electrophotographic photosensitive member for wet development is used as a wet developer by using a specific binder resin and a hole transport agent having a specific molecular weight in combination. Formation with a multilayer electrophotographic photosensitive member for wet development with a small amount of elution of hole transport agent and excellent sensitivity characteristics even when immersed in a hydrocarbon solvent for a long time An apparatus can be provided.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to a multilayer electrophotographic photoreceptor for wet development and an image forming apparatus of the present invention will be specifically described below with reference to the drawings as appropriate.

[First embodiment]
The first embodiment is a multilayer electrophotographic photosensitive member for wet development comprising a charge generation layer containing a charge generation agent, and a charge transport layer containing a hole transfer agent and a binder resin, and the hole transfer agent Is a laminated type electrophotographic photosensitive member for wet development containing a polycarbonate resin represented by the following general formula (1) as a binder resin.

(R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ in the general formula (1) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted carbon number of 1 to 12 An alkyl group, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl substituted alkenyl group having 6 to 30 carbon atoms, Alternatively, it is a substituted or unsubstituted condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, and R ⁷ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, a substituted or unsubstituted carbon number. 6-30 aryl groups or trifluoromethyl groups.)

1. Laminated Photoreceptor As shown in FIG. 1 (a), a laminated electrophotographic photoreceptor 20 has a charge generation layer 24 containing a charge generating agent formed on a substrate 12 by means of vapor deposition or coating, Next, a coating liquid containing a hole transporting agent having a molecular weight of 900 or more and a polycarbonate resin represented by the general formula (1) is applied onto the charge generation layer 24, and dried to dry the charge. It can be produced by forming the transport layer 22.
In contrast to the above structure, as shown in FIG. 1B, the charge transport layer 22 may be formed on the substrate 12, and the charge generation layer 24 may be formed thereon.
However, since the charge generation layer 24 is much thinner than the charge transport layer 22, for protection, the charge transport layer 22 is formed on the charge generation layer 24 as shown in FIG. It is more preferable to form

The positive and negative charge type electrophotographic photosensitive member for wet type development is selected depending on the order of formation of the charge generation layer and charge transport layer and the type of charge transport agent used in the charge transport layer. In the case of a multilayer electrophotographic photosensitive member, the residual potential of the photosensitive member is greatly reduced, and the sensitivity can be improved.
Regarding the thickness of the photoreceptor layer in the multilayer photoreceptor, the charge generation layer is about 0.01 to 5 μm, preferably about 0.1 to 3 μm, and the charge transport layer is 2 to 100 μm, preferably 5 to 5 μm. It is about 50 μm.

As the substrate on which such a photoreceptor layer is formed, various conductive materials can be used, for example, iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium. And metals such as titanium, nickel, palladium, indium, stainless steel, and brass, plastic materials on which the above metal is vapor-deposited or laminated, glass coated with aluminum iodide, tin oxide, indium oxide, and the like.
Further, the shape of the conductive substrate may be any of a sheet shape, a drum shape, or the like in accordance with the structure of the image forming apparatus to be used. The substrate itself is conductive or the surface of the substrate is conductive. As long as it has. The conductive substrate preferably has sufficient mechanical strength when used.

In addition, as shown in FIG. 1C, it is also preferable to previously form the intermediate layer 25 on the substrate 12 before forming the photoreceptor layer. The reason for this is that by providing such an intermediate layer 25, it is possible to prevent the charge on the substrate side from being easily injected into the photoreceptor layer, and to firmly bond the photoreceptor layer onto the substrate 12, thereby This is because the above defects can be covered and smoothed.
Furthermore, the shape of the substrate may be any of a sheet shape, a drum shape, or the like according to the structure of the image forming apparatus to be used. The substrate itself has conductivity or the surface of the substrate has conductivity. If you do. Further, it is preferable that the substrate has a sufficient mechanical strength when used, such as aluminum, and is lightweight.

2. Binder Resin (1) Type A polycarbonate resin represented by the general formula (1) is used as the binder resin used in the electrophotographic photosensitive member for multilayer wet development of the present invention.
The reason for this is that by using a polycarbonate resin, durability and heat resistance can be improved, and a predetermined sensitivity characteristic can be maintained not only in the initial stage but also when used for a long time. . In addition, such a polycarbonate is hardly soluble in a hydrocarbon solvent and has high oil repellency. As a result, the interaction between the surface of the photoreceptor layer and the above-described hydrocarbon solvent is reduced, and the change in appearance of the surface of the photoreceptor layer is reduced over a long period of time.

It is also preferred R ⁵ and R ⁶ in the general formula (1) is a hydrogen atom.
The reason for this is that when R ⁵ and R ⁶ are hydrogen atoms, the compatibility with the hole transport agent is improved, and the film is immersed in a hydrocarbon solvent used as a developer for a long time. Even if it exists, it is because the elution amount of a hole transport agent can be made very small, and the lamination type electrophotographic photoreceptor for wet development excellent in durability and a sensitivity characteristic can be provided. Further, since the polycarbonate resin having such a structure is easy to manufacture, a laminated electrophotographic photosensitive member for wet development having excellent characteristics can be stably manufactured.

Further, it is preferable that R ⁷ in the general formula (1) is an alkyl group having 1 to 3 carbon atoms.
The reason for this is that R ⁷ is a polycarbonate resin having a specific substituent, so that the compatibility with the hole transport agent is further improved, and the resin is immersed in a hydrocarbon solvent used as a developer for a long time. Even in this case, it is possible to provide a multilayer electrophotographic photosensitive member for wet development in which the elution amount of the hole transport agent is extremely small.

(2) Specific examples Here, specific examples of the copolymer polycarbonate represented by the general formula (1) include, for example, compounds represented by the following formulas (9) to (12) (Resin-A to Resin-D). Is mentioned. In addition, the compound represented by Formula (10) has couple | bonded in the location represented by symbol *, and has shown that it is a copolymer.

  In addition, it is also preferable to use various resins that have been used in conventional electrophotographic photoreceptors for wet development. For example, polycarbonate resin such as bisphenol Z type, bisphenol ZC type, bisphenol C type, bisphenol A type, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer Polymer, styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, Thermoplastic resins such as polyamide resin, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, epoxy resin, phenol resin, urea resin, melamine Fat, other crosslinking thermosetting resins, epoxy acrylate, urethane - resin such as photocurable resin such as acrylate can be used.

3. Hole transport agent (1) type The hole transport agent used in the multilayer electrophotographic photosensitive member for wet development of the present invention includes a compound having a molecular weight of 900 or more.
The reason for this is that if the molecular weight is above such a value, the compatibility with a specific binder resin will be good, the amount of elution into the developer will be small, and the laminate will have excellent solvent resistance and durability. This is because an electrophotographic photoreceptor for mold wet development can be provided. The molecular weight of the hole transport agent can be calculated based on the chemical structural formula using Chem Draw Std version 8 (manufactured by Cambridge Soft), or can be calculated using a mass spectrum.

Here, the relationship between the molecular weight of the hole transport agent and the elution amount of the hole transport agent will be described with reference to FIG. The horizontal axis of FIG. 2 shows the molecular weight of the hole transporting agent used in the multilayer electrophotographic photosensitive member for wet development, and the vertical axis shows the hole transport measured by the solvent resistance evaluation described later. The elution amount (g / cm ³ ) of the agent is shown.
As can be understood from FIG. 2, it can be seen that the elution amount of the hole transport agent decreases as the molecular weight of the hole transport agent increases. Furthermore, it can be seen that when the molecular weight of the hole transfer agent is 900 or more, the elution amount of the hole transfer agent is 1 × 10 ⁻⁶ (g / cm ³ ) or less, and excellent solvent resistance is exhibited.
Moreover, with reference to FIG. 3, the relationship between the elution amount of a hole transport agent and a sensitivity change is demonstrated. The horizontal axis of FIG. 3 shows the elution amount (g / cm ³ ) of the hole transport agent, and the vertical axis shows the layered electrophotographic photoreceptor for wet development measured by sensitivity evaluation described later. Sensitivity change (V) is shown.
As can be understood from FIG. 3, when the elution amount of the hole transport agent becomes a value of 1 × 10 ⁻⁶ (g / cm ³ ) or less, the sensitivity change becomes a value of 5 (V) or less, and excellent sensitivity. It can be seen that the characteristics are shown.
Therefore, by controlling the molecular weight value of the hole transport agent to a value greater than or equal to a predetermined value, the elution amount of the hole transport agent can be effectively reduced, and the sensitivity change of the electrophotographic photoreceptor for wet development can be significantly reduced. Can be small.
However, when the molecular weight of the hole transport agent becomes excessively large, the dispersibility in the photosensitive layer is lowered, and the hole transport ability may be lowered.
Therefore, the molecular weight of the hole transport agent is more preferably set to a value within the range of 900 to 4000, and further preferably set to a value within the range of 900 to 2500.

Moreover, it is preferable that the hole transport agent includes a structure represented by the following general formula (2) or (3).
The reason for this is that by including such a structure as a hole transporting agent, the compatibility with a specific polycarbonate resin is further improved, and the efficiency of hole injection from the charge generating agent is increased. Therefore, an electrophotographic photoreceptor for wet development that is further excellent in durability and sensitivity characteristics can be provided.

(R ^{8 to} R ¹⁴ in the general formula (2) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number 1 to 1 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms, A substituted unsaturated hydrocarbon group represented by the general formula (4), a substituent represented by —OR ¹⁵ (R ¹⁵ is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 30 carbon atoms). Or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of R ^{8 to} R ^14. )

(R ^{16 to} R ²¹ in the general formula (3) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number 1 to 1 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms, substituted unsaturated hydrocarbon group represented by the general formula ^{(4), -OR 22 (R} 22 is an alkyl group or an aryl group having 6 to 30 carbon atoms, having 1 to 10 carbon atoms.) represented by substituted by Or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of R ^{16 to} R ^21. )

(R ²³ and R ²⁴ in the general formula (4) are each independently a hydrogen atom, a halogen atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon atom having 1 to 12 carbon atoms. A halogenated alkyl group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and the repeating number c is an integer of 0 to 2.)

More specifically, it is preferable to use compounds represented by the following general formulas (5) to (8) as the kind of the hole transport agent.
The reason is that by using a stilbene compound with a specific enamine structure or triphenylamine structure introduced at a predetermined position in the molecule, the solvent resistance to paraffinic solvents represented by Isopar (trade name) is remarkably increased. This is because it can be improved. Therefore, stable image formation can be carried out over a long period of time by the electrophotographic photoreceptor for wet development.
In addition, by using a stilbene compound having such a specific structure introduced at the molecular end, not only the sensitivity characteristics can be further improved, but also the mechanical characteristics and film formability can be improved.

(Several R ^{25 to} R ³² in the general formula (5) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. A halogenated alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 12 carbon atoms, a substituted or unsubstituted aryl group having 1 to 30 carbon atoms, and X ₁ is a substituted or unsubstituted carbon number. An arylene group having 6 to 30 carbon atoms, an unsaturated hydrocarbon group having an aryl group having 6 to 30 carbon atoms, or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, wherein the repeating number d is an integer of 0 to 2 .)

(Several R ^{33 to} R ⁴⁰ in the general formula (6) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms , represented by substituted unsaturated hydrocarbon group represented by the general formula ^{(4), -OR 41 (R} 41 is an alkyl group or an aryl group having 6 to 30 carbon atoms, having 1 to 10 carbon atoms.) A substituent, or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of a plurality of R ^{33 to} R ^40. )

(Several R ^{42 to} R ⁴⁷ in the general formula (7) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms And a substituted unsaturated hydrocarbon group represented by the general formula (4), —OR ⁴⁸ (R ⁴⁸ is an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms). A substituted polycyclic hydrocarbon group formed by combining or condensing two or more of a plurality of R ^{42 to} R ⁴⁷ , and X ² is a substituted or unsubstituted arylene having 6 to 30 carbon atoms Group having an aryl group having 6 to 30 carbon atoms Hydrocarbon group, or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms.)

(Several R ^{49 to} R ⁵⁵ in the general formula (8) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms , substituted unsaturated hydrocarbon group represented by formula (4) or -OR ^56, (R ⁵⁶ is an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms.) are represented by Or a condensed polycyclic hydrocarbon group formed by combining or condensing two or more of a plurality of R ^{49 to} R ⁵⁵ , the repeating number e is an integer of 0 to 2, and X ³ is Substituted or unsubstituted arylene having 6 to 30 carbon atoms An unsaturated hydrocarbon group or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms.)

(2) Specific example As an example of a compound represented by general formula (5)-(8), the compound (HTM-AF) shown by following formula (13)-(18) is mentioned, for example.

  It is also preferable to use a conventionally known hole transport agent in combination. Examples of such hole transporting agents include N, N, N ′, N′-tetraphenylbenzidine derivatives, N, N, N ′, N′-tetraphenylphenylenediamine derivatives, N, N, N ′, N ′. -Tetraphenylnaphthylenediamine derivatives, N, N, N ', N'-tetraphenylphenanthrylenediamine derivatives, 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, etc. Oxadiazole compounds, styryl compounds such as 9- (4-diethylaminostyryl) anthracene, carbazole compounds such as polyvinylcarbazole, organic polysilane compounds, pyrazolines such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline Compounds, hydrazone compounds, indole compounds, oxazole compounds, isoxazols System compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and nitrogen-containing cyclic compounds such as triazole compounds, and condensed polycyclic compounds.

(3) Addition amount With respect to the addition amount of the hole transport agent, it is preferable to set the value within a range of 10 to 80 parts by weight with respect to 100 parts by weight of the binder resin.
The reason for this is that when the amount of the hole transport agent added is less than 10 parts by weight, the sensitivity is lowered and a practical problem may occur. On the other hand, when the added amount of the hole transport agent exceeds 100 parts by weight, the hole transport agent is likely to be crystallized, and an appropriate film as a photoreceptor may not be formed.
Therefore, it is more preferable to set the addition amount of the hole transport agent to a value within the range of 30 to 70 parts by weight.

4). Charge generation layer (1) Charge generation agent (1) -1 type As the charge generation agent used in the electrophotographic photosensitive member of the present invention, metal-free phthalocyanine (τ type or x type), titanyl phthalocyanine (α type or Y) Type), hydroxygallium phthalocyanine (V type), and at least one compound selected from the group consisting of chlorogallium phthalocyanine (type II).
This is because by specifying the type of the charge generating agent, it is possible to provide a laminated electrophotographic photosensitive member with more excellent sensitivity characteristics, electrical characteristics, stability, and the like.

(1) -2 Specific Examples Among these charge generating agents, specifically, it is more preferable to use phthalocyanine pigments (CGM-A to D) represented by the following formulas (19) to (22).

Of the charge generating agents used in the electrophotographic photosensitive member of the present invention, it is more preferable to use titanyl phthalocyanine (Y type).
This is because an electrophotographic photoreceptor having excellent sensitivity can be provided by using titanyl phthalocyanine (Y type).

Of the charge generators used in the electrophotographic photosensitive member of the present invention, titanyl phthalocyanine (Y type) represented by the formula (20) has at least a black angle of 2θ ± 0. 2 ° = 27.2 ° has a maximum peak, 26.2 ° has no peak, and in differential scanning calorimetry, a temperature from 50 ° C. to 400 ° C. other than the peak due to vaporization of adsorbed water It is preferable not to have a peak of change.
This is because when titanyl phthalocyanine (Y type) satisfies the above-described physical properties, the stability of the crystal of titanyl phthalocyanine in an organic solvent is excellent, and crystal transition can be suppressed. By using such titanyl phthalocyanine (Y type) in the photoreceptor coating solution, it is possible to provide an electrophotographic photoreceptor that maintains good sensitivity characteristics over a long period of time.

Among the charge generating agents used in the electrophotographic photoreceptor of the present invention, the method for producing titanyl phthalocyanine (Y type) represented by the formula (20) includes the following steps (1) and (2). It is preferable.
Step (1): A titanyl phthalocyanine compound is added to a water-soluble organic solvent, and the mixture is stirred for a certain period of time under heating, and then the liquid is allowed to stand for a certain period of time under a temperature condition lower than that of the agitation process to be stabilized. Step (2) of pigmentation pretreatment to be treated: After dissolving the crude crystals of titanyl phthalocyanine compound obtained by removing the water-soluble organic solvent in a solvent, this solution is dropped into a poor solvent and the titanyl phthalocyanine compound is added. Step of pigmentation in which recrystallization is carried out, followed by milling in a non-aqueous solvent in the presence of water

Moreover, it is also preferable to use the manufacturing method represented by the following process (2 ') for the process (2) of this titanyl phthalocyanine manufacturing method.
Step (2 ′): A crude crystal of a titanyl phthalocyanine compound obtained by removing the water-soluble organic solvent from the pigmentation pretreatment liquid obtained in the above step (1) was treated by an acid paste method, and obtained. Milling a low crystalline titanyl phthalocyanine compound in a non-aqueous solvent in the presence of water

Various organic solvents can be used as the water-soluble organic solvent used in the step (1). For example, 1 type, or 2 or more types, such as alcohol, such as methanol, ethanol, and isopropanol, N, N-dimethylformamide, N, N-dimethylacetamide, propionic acid, acetic acid, N-methylpyrrolidone, ethylene glycol, etc. are mentioned. Note that a water-insoluble organic solvent may be added to the water-soluble organic solvent in a small amount.
Moreover, although the conditions of the stirring process among the pigmentation pretreatments are not particularly limited, it is preferable to perform the stirring process for about 1 to 3 hours under a constant temperature condition of about 70 to 200 ° C.
Further, the conditions for the stabilization treatment after the stirring treatment are not particularly limited, but the solution is about 5 to 10 hours under a constant temperature condition of about 10 to 50 ° C., particularly preferably about 23 ± 1 ° C. It is preferable to stand and stabilize.

Further, after completion of the pre-pigmentation treatment, the crude crystal of the titanyl phthalocyanine compound obtained by removing the water-soluble organic solvent is further dissolved in a solvent according to a conventional method, and then dropped into a poor solvent for recrystallization, It is preferable to form a pigment through steps such as filtration, washing with water, milling, filtration, and drying.
Here, the milling process is a process of dispersing and stirring in a non-aqueous solvent in a state where water is present without drying the solid after washing with water. Examples of the solvent for dissolving the crude crystals include halogenated hydrocarbons such as dichloromethane, chloroform, ethyl bromide and butyl bromide, trihaloacetic acids such as trifluoroacetic acid, trichloroacetic acid and tribromoacetic acid, and sulfuric acid. Or arbitrary combinations of 2 or more types are mentioned.
Examples of the poor solvent for recrystallization include water, alcohols such as methanol, ethanol, and isopropanol, and water-soluble organic solvents such as acetone and dioxane. Used in any combination of two or more. Furthermore, examples of non-aqueous solvents for milling include halogen solvents such as chlorobenzene and dichloromethane.

  In addition, examples of the acid used in the acid paste method include concentrated sulfuric acid and sulfonic acid. The non-aqueous solvent used for the milling treatment is the same as described above.

  The titanyl phthalocyanine represented by the formula (20) includes a phthalonitrile represented by the formula (23) and a titanium alkoxide represented by the formula (24) as shown in the following reaction formula (1). Or, as shown in the following reaction formula (2), 1,3-diiminoindoline represented by the formula (25) and a titanium alkoxide represented by the formula (24) are reacted, It is preferable to synthesize.

(R ⁵⁷ in the reaction formula (1) is an alkyl group having 1 to 6 carbon atoms.)

(R ⁵⁷ in the reaction formula (2) is an alkyl group having 1 to 6 carbon atoms.)

  It is also preferable to use a conventionally known charge generating agent. Such charge generators include phthalocyanine pigments such as oxo titanyl phthalocyanine, perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo Organic photoconductors such as pigments, azulenium pigments, cyanine pigments, pyrylium pigments, ansanthrone pigments, triphenylmethane pigments, selenium pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments, selenium, selenium-tellurium, selenium- Examples of the inorganic photoconductive agent material such as arsenic, cadmium sulfide, and amorphous silicon may be used singly or as a mixture of two or more.

In addition, in the method of forming the charge generation layer by forming a charge generation layer coating liquid, coating and drying, the amount of the charge generation agent added is 5 when the binder resin in the charge generation layer is 100 parts by weight. A value within the range of ˜500 parts by weight is preferred.
The reason for this is that when the added amount of the plurality of charge generating agents is less than 5 parts by weight, the effect of increasing the quantum yield becomes insufficient, and the sensitivity, electrical characteristics, stability, etc. of the electrophotographic photosensitive member are improved. It is because it becomes impossible. On the other hand, when the added amount of the plurality of charge generating agents exceeds 500 parts by weight, the extinction coefficient for light having an absorption wavelength in the infrared or near infrared region decreases, and the sensitivity, electrical characteristics, This is because the stability and the like may decrease accordingly.
Therefore, it is more preferable to set the addition amount of the charge generating agent to a value within the range of 30 to 300 parts by weight.

(2) Binder Resin As the binder resin used for the charge generation layer, various resins conventionally used for the photoreceptor layer can be used. As a kind of binder resin, what was described by description of the binder resin mentioned above is mentioned, for example.

5. Electron Transfer Agent (1) Type Further, the charge transport layer of the multilayer electrophotographic photoreceptor of the present invention may further contain an electron transport agent. The reason for this is that by including an electron transport agent in the charge transport layer, electrons accumulated in the electron transport layer can be transported efficiently, and the residual potential can be lowered to improve sensitivity characteristics.

Moreover, it is preferable that the electron transport agent includes at least one compound selected from the group consisting of a naphthalenecarboxylic acid diimide derivative, a naphthoquinone derivative, and an azoquinone derivative.
This is because by using a specific compound as the electron transport agent, it is possible to provide an electrophotographic photoreceptor for wet development that has excellent electron acceptability and excellent sensitivity characteristics and solvent resistance. is there.
It is also preferable to select an electron transport agent that can form a CT complex with the hole transport agent. This is because the electron transporting agent and the hole transporting agent form a CT complex, so that the hole transporting agent can be suppressed by being immersed in a hydrocarbon solvent (liquid developer).

  Specific examples of the electron transporting agent include various compounds having high electron transporting ability, for example, compounds represented by the following formulas (26) to (36) (ETM-A to K).

It is also preferable to use a conventionally known electron transport agent in combination. Examples of such electron transporting agents include diphenoquinone derivatives, benzoquinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, Dinitroacridine derivatives, nitroantharaquinone derivatives, dinitroanthraquinone derivatives, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride And various compounds having electron-accepting properties such as dibromomaleic anhydride, and preferably used alone or in combination of two or more.
Of these compounds, compounds having an electron mobility of 1.0 × 10 ⁻⁸ cm ² / V / sec or more at an electric field strength of 5 × 10 ⁵ V / cm are more preferable.

(2) Addition amount When adding an electron transport agent, it is preferable to set it as the value within the range of 10-100 weight part with respect to 100 weight part of binder resin.
The reason for this is that when the added amount of the plurality of electron transfer agents is less than 10 parts by weight, the sensitivity is lowered and a practical problem may occur. On the other hand, when the added amount of the plurality of electron transfer agents exceeds 100 parts by weight, the electron transfer agent is likely to be crystallized, and an appropriate film as a photoreceptor may not be formed.
Therefore, when adding an electron transport agent, it is more preferable to make the addition amount of an electron transport agent into the value within the range of 20-80 weight part.

In addition, when determining the addition amount of an electron transport agent, it is preferable to consider the addition amount of the hole transport agent mentioned above. More specifically, the addition ratio (total ETM / total HTM) of the electron transport agent (total ETM) is a value within the range of 0.25 to 1.3 with respect to the hole transport agent (total HTM). It is preferable to do.
This is because if the ratio of all ETMs / all HTMs is outside this range, the sensitivity is lowered, which may cause practical problems.
Therefore, it is more preferable that the ratio of the total ETM / total HTM is set to a value within the range of 0.5 to 1.25.

6). Additives In addition to the above-described components, the photoreceptor layer includes various conventionally known additives such as antioxidants, radical scavengers, singlet quenchers, and the like within a range that does not adversely affect the electrophotographic characteristics. Deterioration inhibitors such as UV absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be blended. In order to improve the sensitivity of the photoreceptor layer, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.

7). Intermediate layer In constituting the multilayer electrophotographic photosensitive member of the present invention, an intermediate layer is preferably formed on the substrate. The reason for this is that by forming an intermediate layer on the substrate, the adhesion between the photoreceptor layer and the substrate can be improved and the surface of the substrate can be smoothed. This is because it can be coated and the residual potential can be further reduced.

(1) Binder Resin As the binder resin used for the intermediate layer, various resins conventionally used for the photoreceptor layer can be used. As a kind of binder resin, what was described by description of the binder resin mentioned above is mentioned, for example.
Moreover, as the binder resin used for the intermediate layer, a resin excellent in solvent resistance is more preferable. The reason for this is that if the solvent resistance of the binder resin used in the intermediate layer is low, it will be dissolved in the photoreceptor layer applied on the intermediate layer, making it difficult to properly form the intermediate layer. Because there are cases. Specifically, resins that form a three-dimensional network structure such as acrylic resin, alkyd resin, polyurethane, melamine resin, epoxy resin, phenol resin, urea resin, polyamide, polyester, maleic acid resin, isocyanate resin, and silicon resin Is mentioned. Moreover, since it is further excellent in solvent resistance, a phenol resin and polyamide are more preferable.

(2) Additives Additives to be added to the intermediate layer are in a range where sedimentation at the time of production does not become a problem, and light scattering is caused to prevent the generation of interference fringes or to improve dispersibility. It is also preferable to add a small amount of various additives (organic fine powder or inorganic fine powder) for the purpose of improving conductivity.
In addition, the types of additives contained in the intermediate layer include inorganic pigments such as white pigments such as titanium oxide, zinc oxide, zinc white, zinc sulfide, lead white, and lithopone, and extender pigments such as alumina, calcium carbonate, and barium sulfate. Examples thereof include pigments, fluorine resin particles, benzoguanamine resin particles, and styrene resin particles.
Moreover, when adding additives, such as a fine powder, it is preferable to make the average particle diameter into the value within the range of 0.01-3 micrometers. This is because if the particle size is too large, the unevenness of the intermediate layer may increase, an electrically non-uniform portion may occur, and image quality defects may easily occur. On the other hand, if the particle size is too small, a sufficient light scattering effect may not be obtained.
In addition, when adding additives, such as a fine powder, the addition amount shall be the value of 70 weight% or less in a weight conversion with respect to solid content of an intermediate | middle layer, and the value within the range of 0.01-50 weight%. It is more preferable to set the value within the range of 0.01 to 30% by weight.

  In addition, it is also preferable that the intermediate layer contains a conventionally known charge transport agent, charge generator and the like. These compounds may be used alone or in combination of two or more. For example, examples of the charge transporting agent and the charge generating agent include those described in the above description of the hole transporting agent, the electron transporting agent, and the charge generating agent.

(3) Film thickness In addition, since the concealability of the unevenness in the support base material is increased by increasing the film thickness of the intermediate layer, spot-like image quality defects are preferred in the direction of reduction, but on the contrary, Electrical characteristics such as an increase in residual potential tend to decrease.
Accordingly, the thickness of the intermediate layer is preferably set to a value within the range of 0.1 to 50 μm, and more preferably set to a value within the range of 1 to 30 μm.

8). Manufacturing Method Regarding the manufacturing method of the multilayer photoreceptor layer of the present invention, a charge transport layer coating solution and a charge generation layer coating solution are prepared as described below, applied onto a substrate, and then dried. It is preferable to manufacture.

(1) Coating liquid preparation process The coating liquid preparation process includes, for example, a coating liquid for a charge transport layer comprising a binder resin, a hole transport agent, and a solvent, a binder resin, a charge generator, and a solvent. And a charge generation layer coating solution comprising: For example, it is preferable to disperse and mix using a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic disperser or the like to obtain a coating solution.
More specifically, the solid content concentration of the charge transport layer coating solution is within the range of 10 to 30% by weight, and the solid content concentration of the charge generation layer coating solution is within the range of 1 to 10% by weight. It is preferable to prepare a coating solution. The reason for this is that if the solid content concentration of the coating solution for the charge transport layer is less than 10% by weight, a coating defect may occur, whereas the solid content concentration of the coating solution exceeds 30% by weight. This is because unevenness of layers is likely to occur, and it may be difficult to form a thin film having a uniform thickness as a photoreceptor. Similarly, if the solid content concentration of the coating solution for the charge generation layer is less than 1% by weight, film defects may occur. If the solid content concentration exceeds 10% by weight, unevenness of the layer is likely to occur. It may be difficult to form a thin film having a uniform thickness as a body.

Various organic solvents can be used as the solvent for preparing the charge transport layer coating solution and the charge generation layer coating solution. For example, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane, chloroform and tetrachloride Halogenated hydrocarbons such as carbon and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dioxane and dioxolane; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Class, dimethylformaldehyde, dimethylformamide, dimethylsulfoxide, etc., alone or in combination of two or more. That.
Furthermore, in order to improve the dispersibility of the charge transport agent, the charge generator, etc. and the smoothness on the surface of the photoreceptor layer, it is also preferable to add a surfactant, a leveling agent or the like when preparing the coating solution.

(2) Coating step and drying step The first coating step and the first drying step, the second coating step and the second drying step may be provided to form a photoreceptor layer comprising a charge transport layer and a charge generation layer. preferable. For example, as shown in FIG. 1A, a charge generation layer coating solution is applied in the first application step, and the charge generation layer coating film is dried in the first drying step, thereby generating charges on the substrate 12. The layer 24 is formed, and then the charge transport layer coating solution is applied in the second coating process, and the charge transport layer coating film is dried in the second drying process, and the charge transport layer 22 is formed on the charge generation layer 24. Is preferably formed.

(2) -1 Application Step In carrying out the application step, it is also preferable to apply the application liquid directly on the substrate, or to apply it indirectly via an intermediate layer.
As a coating method, it is preferable to use, for example, a spin coater, an applicator, a spray coater, a bar coater, a dip coater, a doctor blade, etc., in order to form a photoreceptor layer having a uniform thickness.
The charge generation layer preferably has a thinner coating than the charge transport layer in order to reduce the residual potential.

(2) -2 Drying step Further, after the coating step, in the drying step, it is preferable to dry at a drying temperature of, for example, 60 ° C. to 150 ° C. using a high-temperature dryer, a vacuum dryer or the like. This is because when the drying temperature is less than 60 ° C., the drying time becomes excessively long, and it may be difficult to efficiently form a photoreceptor layer having a uniform thickness. is there. On the other hand, if the drying temperature exceeds 150 ° C., the photoconductor may be thermally decomposed.

In forming the multilayer electrophotographic photosensitive member of the present invention, when forming an intermediate layer on the substrate, as shown in FIG. 1 (c), an intermediate layer 25 is formed on the substrate 12, Next, it is preferable to form a charge generation layer and a charge transport layer.
In addition, about the conditions of a coating liquid preparation process, a coating process, and a drying process, it can apply to the manufacturing method of a charge generation layer and a charge transport layer. The intermediate layer coating solution is preferably prepared from, for example, a binder resin and an additive.

[Second Embodiment]
The second embodiment is an image forming apparatus including the electrophotographic photosensitive member of the first embodiment.
In this example of the image forming apparatus, the case where the multilayer electrophotographic photosensitive member of the present invention is used as an electrophotographic photosensitive member will be described.

  In carrying out the image forming method of the second embodiment, a copying machine 40 which is an image forming apparatus as shown in FIG. 4 can be preferably used. The copying machine 40 includes an image forming unit 41, a paper discharge unit 42, an image reading unit 43, and a document feeding unit 44. The image forming unit 41 further includes an image forming unit 41a and a paper feeding unit 41b. In the illustrated example, the document feeding unit 44 includes a document placing tray 44a, a document feeding mechanism 44b, and a document discharge tray 44c, and the document placed on the document placing tray 44a. Is sent to the image reading position P by the document feeding mechanism 44b and then discharged to the document discharge tray 44c.

Then, when the document is sent to the document reading position P, the image reading unit 43 reads the image on the document using the light from the light source 43a. That is, an image signal corresponding to the image on the document is formed using an optical element 43b such as a CCD.
On the other hand, recording sheets (hereinafter simply referred to as “sheets”) S stacked on the sheet feeding unit 41b are sent one by one to the image forming unit 41a. The image forming unit 41a is provided with a photosensitive drum 51 as an image carrier, and around the photosensitive drum 51, a charger 52, an exposure unit 53, a developing unit 54, and a transfer roller. 55 and a cleaning device 56 are arranged along the rotation direction of the photosensitive drum 51.

  Among these components, the photosensitive drum 51 is rotationally driven in the direction indicated by the solid line arrow in the drawing, and the surface thereof is uniformly charged by the charger 52. Thereafter, an exposure process is performed on the photosensitive drum 51 by the exposure device 53 based on the above-described image signal, and an electrostatic latent image is formed on the surface of the photosensitive drum 51. Based on the electrostatic latent image, the developing device 54 attaches toner and develops it, thereby forming a toner image on the surface of the photosensitive drum 51. The toner image is transferred as a transfer image onto the sheet S conveyed to the nip portion between the photosensitive drum 51 and the transfer roller 55. Next, the sheet S on which the transferred image is transferred is conveyed to the fixing unit 57 and a fixing process is performed.

Here, the paper S after fixing is sent to the paper discharge unit 42. However, when performing post-processing (for example, stapling processing), the paper S is sent to the intermediate tray 42a and then back. Processing is performed. Thereafter, the sheet S is discharged to a discharge tray portion (not shown) provided on the side surface of the image forming apparatus. On the other hand, when no post-processing is performed, the sheet S is discharged to a discharge tray 42b provided below the intermediate tray 42a.
The intermediate tray 42a and the paper discharge tray 42b are configured as a so-called in-body paper discharge unit.
After the transfer is performed as described above, the residual toner (and paper dust) remaining on the photosensitive drum 51 is removed by the cleaning device 56. That is, while the photosensitive drum 51 is cleaned, residual toner is collected in a waste toner container (not shown).

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

[Example 1]
(1) Preparation of electrophotographic photoreceptor for wet development 1 part by weight of Y-type oxotitanyl phthalocyanine (CGM-B) represented by formula (20) as a charge generator and polyvinyl butyral ESREC BM as a binder resin -1 (Sekisui Chemical Co., Ltd.) 1 part by weight and 50 parts by weight of diacetone alcohol were accommodated and then mixed and dispersed in a ball mill for 48 hours to prepare a charge generation layer use working solution. Next, the obtained coating solution was applied by dipping on an aluminum tube having a diameter of 30 mm and a length of 254 mm, and then dried at 70 ° C. for 10 minutes to obtain an electric charge having an average film thickness of 0.3 μm. A generation layer was formed.
Further, 50 parts by weight of a stilbene derivative (HTM-A) represented by the formula (13) as a hole transport agent and 50,000 having a viscosity average molecular weight represented by the formula (9) as a binder resin 100 parts by weight of a polycarbonate resin (Resin-A), 0.1 part by weight of KF-96-50CS (manufactured by Shin-Etsu Chemical Co., Ltd.) which is a dimethyl silicone oil as a leveling agent, 700 parts by weight of tetrahydrofuran as a solvent, Was accommodated and dispersed for 48 hours to prepare a charge transport coating solution. Next, the obtained coating solution was applied on the charge generation layer by dipping and then dried at 130 ° C. for 30 minutes to form a charge transport layer having an average film thickness of 20 μm. In this way, the multilayer photoreceptor of Example 1 was prepared.
In addition, the viscosity average molecular weight (M) of the copolymer polycarbonate resin was calculated from [η] = 1.23 × 10 ⁻⁴ M ^{0.83 according} to Schnell's equation by obtaining the intrinsic viscosity [η] with an Ostwald viscometer. [Η] can be measured from a polycarbonate resin solution obtained by dissolving a polycarbonate resin at 20 ° C. using a methylene chloride solution as a solvent so that the concentration (C) is 6.0 g / dm ^3. it can.

(2) Evaluation (2) -1 Sensitivity evaluation The sensitivity of the obtained electrophotographic photoreceptor for wet development was measured. That is, using a drum sensitivity tester (produced by GENTEC), it was charged to 700 V, and then monochromatic light with a wavelength of 780 nm (half-value width: 20 nm, light amount) extracted from the light of the halogen lamp using a hand pulse filter. : 1.0 μJ / cm ² ). The potential after the elapse of 330 msec after the exposure was measured and used as the initial sensitivity (V).
The entire electrophotographic photosensitive member for wet development was immersed in a hydrocarbon solvent (Isopar L, manufactured by Exxon Chemical Co., Ltd.) used as a developer for wet development at a temperature of 25 ° C. for 2000 hours. . Thereafter, the electrophotographic photosensitive member for wet development was taken out from the hydrocarbon-based solvent, the sensitivity was measured in the same manner, and the difference between the initial sensitivity and the sensitivity after isopar immersion was calculated, and the change in sensitivity (V) was obtained. The obtained results are shown in Table 1.

(2) -2 Evaluation of Solvent Resistance Into 500 ml of a hydrocarbon-based solvent (Isopar L, manufactured by Exxon Chemical Co., Ltd.), the obtained electrophotographic photosensitive member for wet developing is obtained so that the entire surface of the photosensitive layer is immersed. It was immersed under conditions of a temperature of 25 ° C. and 2000 hours. On the other hand, the concentration of the hole transport agent was changed and dissolved in a hydrocarbon solvent (Isopar L, manufactured by Exxon Chemical Co., Ltd.). In this state, the absorbance at the absorption peak wavelength from the ultraviolet region to the visible region was measured, and a concentration-absorbance calibration curve for the hole transport agent was prepared in advance. Next, the electrophotographic photoreceptor for wet development immersed in a hydrocarbon solvent (Isopar L, manufactured by Exxon Chemical Co., Ltd.) is subjected to absorption measurement from the ultraviolet region to the visible region. The elution amount of the hole transport agent was calculated from the absorbance at the absorption peak wavelength from the region to the visible region. The obtained results are shown in Table 1.

(2) -3 Appearance Evaluation Further, the appearance of the electrophotographic photoreceptor for wet development after the solvent resistance evaluation was visually observed for occurrence of cracks, and the appearance was evaluated according to the following criteria. The obtained results are shown in Table 1.
A: No change in appearance is observed.
○: No significant change in appearance is observed.
Δ: Some change in appearance is observed.
X: A remarkable change in appearance is observed.

[Examples 2 to 4]
In Examples 2 to 4, instead of the polycarbonate resin represented by Formula (9) as the binder resin used in Example 1, the viscosity average molecular weight represented by Formulas (10) to (12) is 50, A laminate type photoreceptor for wet development was prepared and evaluated in the same manner as in Example 1 except that 000 polycarbonate resin (Resin-BD) was used.

[Examples 5 to 9]
In Examples 5 to 9, instead of the stilbene derivative represented by Formula (13) as the hole transport agent used in Example 1, compounds represented by Formulas (14) to (18) (HTM-B A laminate type photoreceptor for wet development was prepared and evaluated in the same manner as in Example 1 except that ~ F) was used.

[Comparative Examples 1-3]
In Comparative Examples 1 to 3, instead of the polycarbonate resin represented by Formula (9) as the binder resin used in Example 1, a polycarbonate resin represented by the following Formulas (37) to (39) (Resin- Except for the use of E to G), a multilayer photoconductor for wet development was prepared and evaluated in the same manner as in Example 1.

[Comparative Examples 4 to 5]
In Comparative Examples 4 to 5, instead of the stilbene derivative represented by the formula (13) as the hole transport agent used in Example 1, compounds represented by the following formulas (40) to (41) (HTM- Except for the use of G to H), a multilayer photoconductor for wet development was prepared and evaluated in the same manner as in Example 1.

As described above in detail, according to the present invention, by using a specific binder resin and a specific hole transporting agent in combination, an electrophotographic photosensitive film for wet development having excellent solvent resistance and sensitivity characteristics. And an image forming apparatus for wet development provided with the same.
Therefore, the electrophotographic photoreceptor for wet development according to the present invention is expected to contribute to cost reduction, high speed, high performance, etc. in various image forming apparatuses such as copying machines and printers.

(A)-(c) is a figure provided in order to demonstrate the basic structure and deformation | transformation structure of a laminated type photoreceptor. It is a figure provided in order to demonstrate the relationship between the molecular weight of a hole transport agent, and the elution amount of a hole transport agent. It is a figure provided in order to demonstrate the relationship between the elution amount of a hole transport agent, and a sensitivity change. Supplied to explain an image forming apparatus provided with an electrophotographic photosensitive member for wet development

Explanation of symbols

12: Conductive substrate 20: Multilayer photoreceptor 22: Charge transport layer 24: Charge generation layer 25: Intermediate layer 40: Copying machine 40
41: Image forming unit 41a: Image forming 41b: Paper feeding unit 42: Paper discharging unit 43: Image reading unit 44: Document feeding unit 44a: Document loading tray 44b: Document feeding mechanism 44c: Document ejection tray 51: Photosensitive Body drum 52: charger 53: exposure device 54: developing device 55: transfer roller 56: cleaning device 57: fixing unit

Claims (8)

A laminated electrophotographic photoreceptor comprising a charge generation layer containing a charge generation agent and a charge transport layer containing a hole transfer agent and a binder resin on a substrate,
The molecular weight of the hole transport agent is 900 or more,
A multilayer electrophotographic photosensitive member for wet development, comprising a polycarbonate resin represented by the following general formula (1) as the binder resin.

(R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ in the general formula (1) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted carbon number of 1 to 12 An alkyl group, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl substituted alkenyl group having 6 to 30 carbon atoms, Alternatively, it is a substituted or unsubstituted condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, and R ⁷ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, a substituted or unsubstituted carbon number. 6-30 aryl groups or trifluoromethyl groups.) 2. The laminated electrophotographic photoreceptor for wet development according to claim 1, wherein R ⁵ and R ⁶ in the general formula (1) are hydrogen atoms. The multilayer electrophotographic photoreceptor for wet development according to claim 1 or 2, wherein the hole transport agent is a compound having a structure represented by the following general formula (2) or (3).

(R ^{8 to} R ¹⁴ in the general formula (2) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number 1 to 1 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms, A substituted unsaturated hydrocarbon group represented by the general formula (4), a substituent represented by —OR ¹⁵ (R ¹⁵ is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 30 carbon atoms). Or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of R ^{8 to} R ^14. )

(R ^{16 to} R ²¹ in the general formula (3) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number 1 to 1 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms, substituted unsaturated hydrocarbon group represented by the general formula ^{(4), -OR 22 (R} 22 is an alkyl group or an aryl group having 6 to 30 carbon atoms, having 1 to 10 carbon atoms.) represented by substituted by Or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of R ^{16 to} R ^21. )

(R ²³ and R ²⁴ in the general formula (4) are each independently a hydrogen atom, a halogen atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon atom having 1 to 12 carbon atoms. A halogenated alkyl group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and the repeating number c is an integer of 0 to 2.) The multilayer electrophotographic photosensitive member for wet development according to claim 1, wherein the hole transport agent contains at least one compound represented by the following general formulas (5) to (8).

(Several R ^{25 to} R ³² in the general formula (5) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. A halogenated alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 12 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and X ₁ is a substituted or unsubstituted carbon number. An arylene group having 6 to 30 carbon atoms, an unsaturated hydrocarbon group having an aryl group having 6 to 30 carbon atoms, or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, wherein the repeating number d is an integer of 0 to 2 .)

(Several R ^{33 to} R ⁴⁰ in the general formula (6) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms , represented by substituted unsaturated hydrocarbon group represented by the general formula ^{(4), -OR 41 (R} 41 is an alkyl group or an aryl group having 6 to 30 carbon atoms, having 1 to 10 carbon atoms.) A substituent, or a condensed polycyclic hydrocarbon group formed by bonding or condensing two or more of a plurality of R ^{33 to} R ^40. )

(Several R ^{42 to} R ⁴⁷ in the general formula (7) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms And a substituted unsaturated hydrocarbon group represented by the general formula (4), —OR ⁴⁸ (R ⁴⁸ is an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms). A substituted polycyclic hydrocarbon group formed by combining or condensing two or more of a plurality of R ^{42 to} R ⁴⁷ , and X ² is a substituted or unsubstituted arylene having 6 to 30 carbon atoms Group having an aryl group having 6 to 30 carbon atoms Hydrocarbon group, or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms.)

(Several R ^{49 to} R ⁵⁵ in the general formula (8) are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number. 1 to 12 halogenated alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted alkenyl groups having 6 to 30 carbon atoms , substituted unsaturated hydrocarbon group represented by formula (4) or -OR ^56, (R ⁵⁶ is an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms.) are represented by Or a condensed polycyclic hydrocarbon group formed by combining or condensing two or more of a plurality of R ^{49 to} R ⁵⁵ , the repeating number e is an integer of 0 to 2, and X ³ is Substituted or unsubstituted arylene having 6 to 30 carbon atoms An unsaturated hydrocarbon group or a condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms.)   The addition amount of the hole transport agent is set to a value within a range of 10 to 80 parts by weight with respect to 100 parts by weight of the binder resin. A multilayer electrophotographic photoreceptor for wet development.   The multilayer electrophotographic photoreceptor for wet development according to any one of claims 1 to 5, wherein the charge generating agent comprises titanyl phthalocyanine (Y type). The amount of elution of the hole transport agent is 1 × 10 ⁻⁶ g / cm ³ or less when immersed in a hydrocarbon solvent used as a developer for wet development at room temperature for 2000 hours. The multilayer electrophotographic photosensitive member for wet development according to any one of claims 1 to 6.   A multilayer electrophotographic photoreceptor for wet development according to any one of claims 1 to 7, and a charging process, an exposure process, a development process, and a transfer process around the electrophotographic photoreceptor for wet development. An image forming apparatus for wet development, wherein each part for carrying out is disposed and image formation is performed using a liquid developer in which a toner is dispersed in a hydrocarbon solvent in a development step.

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