JP2006065083A - Electrophotographic photoreceptor for wet development, and image forming apparatus for wet development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotophotographic photoreceptor for wet development superior in solvent resistance and ozone proofness a polycarbonate resin of a specific molecular weight as a binder resin, and to provide an image forming apparatus for wet development provided with it. <P>SOLUTION: The electrophotographic photoreceptor for wet development provided with a photoreceptor layer containing the binder resin, a hole transport agent, an electron transport agent and a charge generating agent and the image forming apparatus for wet development provided with it contain the polycarbonate resin as the binder resin, and make a viscosity average molecular weight of the polycarbonate a value in the range of 60,000-80,000. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photoreceptor for wet development and an image forming apparatus for wet development including the same, and more particularly to an electrophotographic photoreceptor for wet development excellent in solvent resistance and ozone resistance and wet development including the same. The present invention relates to an image forming apparatus.

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 an organic photoreceptor is advantageous in that it is easy to manufacture and configure as compared to a conventional inorganic photoreceptor, and it is easy to perform wet development using a liquid developer.
However, there has been a problem that conventional electrophotographic photoreceptors for wet development are easily immersed in a short time by a hydrocarbon solvent (liquid developer).

  Therefore, the present applicant is an electrophotographic photoreceptor for wet development comprising a photoreceptor layer containing a binder resin, a hole transport agent, an electron transport agent, and a charge generator, and the binder resin As an electrophotographic photosensitive member for wet development that has excellent solvent resistance by using a polycarbonate resin containing a specific siloxane structure, for example, Patent Document 1 has already been proposed.

On the other hand, an electrophotographic photoreceptor using a polycarbonate resin containing a bisphenol E-type structural unit that has excellent abrasion resistance and scratch resistance and can maintain electrophotographic characteristics for a long time has been disclosed (for example, Patent Documents). 2).
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 the film was easily immersed in the system solvent (liquid developer) and the hole transport agent and the like were easily eluted.
Therefore, the present inventors have found the fact that by using a polycarbonate resin having a specific molecular weight as the binder resin, the elution amount of the hole transport agent and the like is remarkably reduced and the ozone resistance is also improved. The present invention has been completed.
That is, an object of the present invention is to provide an electrophotographic photoreceptor for wet development excellent in solvent resistance and ozone resistance and an image forming apparatus provided with such an electrophotographic photoreceptor for wet development.

According to the present invention, there is provided an electrophotographic photoreceptor for wet development comprising a photoreceptor layer containing a binder resin, a hole transport agent, an electron transport agent, and a charge generator,
An electrophotographic photosensitive member for wet development that includes a polycarbonate resin as a binder resin and has a viscosity-average molecular weight of the polycarbonate resin in the range of 60,000 to 80,000 is provided to solve the above-described problems. can do.
The viscosity average molecular weight (M) of the polycarbonate resin can be calculated using the following mathematical formula (1). More specifically, [η] (intrinsic viscosity) in the formula (1) can be calculated from the following formula (2), and η _sp (specific viscosity) in the formula (2) is 20 ° C. It can be measured from a polycarbonate resin solution obtained by dissolving a polycarbonate resin so that the concentration (C) is 6.0 g / dm ^{3 using a} methylene chloride solution as a solvent.

[Η] = KM ^a (1)

([Η] in Equation (1) is the intrinsic viscosity, M is the viscosity average molecular weight, K (Mark Fwinck constant) is 1.23 × 10 ⁻⁵ , and a (Mark Fwinck constant) is 0.83.)

η _sp / C = [η] (1 + K′η _sp ) (2)

(Η _sp in the formula (2) is a specific viscosity, C is a polymer concentration (g / dm ³ ), [η] is an intrinsic viscosity, and K ′ is 0.28.)

  In constituting the electrophotographic photoreceptor for wet development according to the present invention, it is preferable that the binder resin includes a polycarbonate resin represented by the following general formula (1).

(R ¹ , R ² , R ³ and R ⁴ in the general formula (1) are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon X is an aryl group of 6 to 30, and X is —O—, —S—, —CO—, —COO—, — (CH ₂ ) ₂ —, —SO—, —SO ₂ —, —CR ⁵ R ^6- , —SiR ⁵ R ⁶ —, or —SiR ⁵ R ⁶ —O— (R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, substituted Alternatively, an unsubstituted aryl group having 6 to 30 carbon atoms, a trifluoromethyl group, or R ⁵ and R ⁶ may form a ring and may have an alkyl group having 1 to 7 carbon atoms as a substituent. 5-12 cycloalkylidene) and Y is a single bond, —O—, or —CO—.

  Further, in constituting the electrophotographic photoreceptor for wet development of the present invention, it is preferable that the hole transport agent contains an amine structure represented by the following general formula (2).

(Formula (2) R ⁷ ~R ¹¹ in are each independently respectively and independently, a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted A substituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted aryl substituted alkenyl group having 6 to 30 carbon atoms, a substituted or unsubstituted condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, or R ⁷ to At least two or more of R ¹¹ are hydrocarbon groups that may be bonded or condensed to form a ring structure.)

  Further, in constituting the electrophotographic photosensitive member for wet development according to the present invention, the amount of the hole transport agent added may be 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. preferable.

  In constituting the electrophotographic photoreceptor for wet development according to the present invention, it is preferable that the molecular weight of the hole transport agent is 900 or more.

  Further, in constituting the electrophotographic photosensitive member for wet development according to the present invention, the addition amount of the electron transfer agent may be set to a value within the range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin. preferable.

  In constituting the electrophotographic photosensitive member for wet development according to the present invention, the I / O value of the binder resin is preferably set to a value of 0.38 or more.

  Further, in constituting the electrophotographic photosensitive member for wet development according to the present invention, the amount of the charge generating agent is set to a value within the range of 0.2 to 40 parts by weight with respect to 100 parts by weight of the binder resin. Is preferred.

  In constructing the electrophotographic photoreceptor for wet development according to the present invention, the organic photoreceptor contains at least a charge generator, a hole transport agent, an electron transport agent and a binder resin on the conductive substrate in the same layer. A single layer type is preferred.

  Another aspect of the present invention includes an electrophotographic photosensitive member for wet development, and at least charging, exposure, development, and transfer steps are arranged around the electrophotographic photosensitive member for wet development. In an image forming apparatus for forming an image using a liquid developer in which a toner is dispersed in a hydrocarbon solvent, an electrophotographic photoreceptor for wet development is formed on a conductive substrate, at least a binder resin, a hole transport agent, An image forming apparatus for wet development, comprising a photoreceptor layer containing an electron transport agent and a charge generator, and having a viscosity average molecular weight of the binder resin in a range of 60,000 to 80,000. .

  According to the electrophotographic photoreceptor for wet development of the present invention, when a binder resin having a specific molecular weight is used, the electrophotographic photoreceptor is immersed in a hydrocarbon solvent used as a developer for wet development for a long time. However, it is possible to provide an electrophotographic photosensitive member for wet development in which the elution amount of the hole transport agent and the like is reduced and the ozone resistance is excellent.

  According to the electrophotographic photoreceptor for wet development of the present invention, by including the polycarbonate resin represented by the general formula (1) as a binder resin, the electrophotographic photoreceptor is immersed in a hydrocarbon solvent used during development for a long time. Even in such a case, it is possible to provide an electrophotographic photoreceptor for wet development that has a small amount of elution of a hole transport agent and the like and is excellent in sensitivity characteristics.

  In addition, according to the electrophotographic photoreceptor for wet development of the present invention, it has excellent compatibility with a polycarbonate resin having a specific molecular weight by including the specific structure represented by the general formula (2) as a hole transport agent. In addition, since the injection efficiency from the charge generating material to the charge transport material is high, an electrophotographic photoreceptor for wet development having excellent durability and sensitivity characteristics can be provided.

  In addition, according to the electrophotographic photoreceptor 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, and further sensitivity is improved. An electrophotographic photoreceptor for wet development having excellent characteristics can be provided.

  Further, according to the electrophotographic photoreceptor for wet development of the present invention, the molecular weight (Mw) of the hole transport agent is set to a predetermined value or more, so that the hydrocarbon solvent used as a developer for wet development can be used. Even when immersed for a long period of time, the amount of elution of the hole transport agent and the like is small and the compatibility with a specific binder resin is good, so that wet development further excellent in solvent resistance and ozone resistance is achieved. An electrophotographic photosensitive member can be provided.

  In addition, according to the electrophotographic photoreceptor for wet development of the present invention, by limiting the addition amount of the electron transport agent to a predetermined range, crystallization of the electron transport agent can be effectively prevented, and further sensitivity characteristics can be improved. In addition, an electrophotographic photoreceptor for wet development can be provided.

  Further, according to the electrophotographic photoreceptor for wet development of the present invention, an electrophotographic photoreceptor for wet development having further excellent solvent resistance is provided by limiting the I / O value of the binder resin to a predetermined range. I can do it.

  In addition, according to the electrophotographic photoreceptor for wet development of the present invention, the effect of increasing the quantum yield is improved by limiting the addition amount of the charge generator to a predetermined range, and sensitivity characteristics, electrical characteristics, etc. are improved. An excellent electrophotographic photoreceptor for wet development can be provided.

  In addition, according to the electrophotographic photosensitive member for wet development of the present invention, an electrophotographic photosensitive member having a predetermined sensitivity over a long period of time can be obtained by making the photosensitive layer a single layer type, although it is easy to configure and manufacture. You can get a body.

  Further, according to the image forming apparatus for wet development of the present invention, the electrophotographic photoreceptor for wet development is immersed in a hydrocarbon solvent used as a wet developer for a long time by using a binder resin having a specific molecular weight. Even in this case, it is possible to provide an image forming apparatus provided with an electrophotographic photosensitive member for wet development that has a small amount of elution of a hole transport agent and the like and is excellent in ozone resistance.

  Hereinafter, embodiments of the electrophotographic photoreceptor for wet development and an image forming apparatus according to the present invention will be specifically described with reference to the drawings as appropriate.

[First embodiment]
A first embodiment is an electrophotographic photosensitive member for wet development including a photosensitive layer including a binder resin, a hole transport agent, an electron transport agent, and a charge generator, and the binder resin As described above, the electrophotographic photosensitive member for wet development includes a polycarbonate resin and has a viscosity average molecular weight of 60,000 to 80,000.

Here, the electrophotographic photosensitive member for wet development includes a single layer type and a laminated type, and the electrophotographic photosensitive member for wet development of the present invention is applicable to both.
However, it can be used for both positive and negative chargeability, has a simple structure and is easy to manufacture, and suppresses film defects when forming the photoreceptor layer, so there are few interfaces between layers, improving optical characteristics For reasons such as being possible, it is more preferable to apply to a single layer type.

1. Single Layer Type Photoreceptor (1) Basic Configuration As shown in FIG. 3A, the single layer type photoreceptor 10 has a single photoreceptor layer 14 provided on a conductive substrate 12.
For example, the photoreceptor layer may further include a binder resin having a viscosity average molecular weight in the range of 60,000 to 80,000, a hole transport agent, an electron transport agent, a charge generating agent, and the like. Accordingly, a leveling agent or the like can be dissolved or dispersed in an appropriate solvent, and the obtained coating solution can be applied on a conductive substrate and dried. Such a single layer type photoreceptor is characterized in that it can be applied to either a positive or negative charge type with a single configuration, has a simple layer configuration, and is excellent in productivity.

  Moreover, since the obtained single layer type photoreceptor includes a polycarbonate resin having a viscosity average molecular weight in the range of 60,000 to 80,000, the solvent resistance and ozone resistance are excellent. There is a feature. Furthermore, when an electron transport agent is contained in the photosensitive layer of the single-layer type photoreceptor, the positive charging sensitivity can be further improved.

(2) Binder resin A polycarbonate resin is used as the binder resin for dispersing the charge generating agent and the like.
This is because such a polycarbonate resin 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.

(2) -1 Viscosity average molecular weight Moreover, it is characterized by making the viscosity average molecular weight of polycarbonate resin into the value within the range of 60,000-80,000.
The reason for this is that by using a polycarbonate resin having a specific molecular weight as the binder resin, even if it is immersed for a long time in a hydrocarbon solvent used as a wet developer, the elution amount of the hole transporting agent and the like This is because it is possible to provide an electrophotographic photosensitive member for wet development that has a small amount and excellent ozone resistance.
That is, when the viscosity average molecular weight of the polycarbonate resin is less than 60,000, the solvent resistance may be lowered. On the other hand, when the viscosity average molecular weight of the polycarbonate resin exceeds 80,000, the ozone resistance is remarkably lowered.
Therefore, the viscosity average molecular weight of the polycarbonate resin is more preferably set to a value within the range of 62,000 to 79,000, and further preferably set to a value within the range of 65,000 to 78,000.

Here, with reference to FIG. 1 and FIG. 2, the influence of the viscosity average molecular weight in polycarbonate resin as binder resin is demonstrated concretely.
First, FIG. 1 shows the relationship between the viscosity average molecular weight of the binder resin and the elution amount of the hole transport agent. The horizontal axis of FIG. 1 shows the viscosity average molecular weight of the binder resin, and the vertical axis shows the elution amount of the hole transport agent after the electrophotographic photoreceptor for wet development is immersed in an isoparaffin solvent for 200 hours (10 ^-7 g / cm ³ ). From FIG. 1, when the viscosity average molecular weight of the binder resin is 60,000 or more, the elution amount of the hole transport agent is 6.0 × 10 ⁻⁷ g / cm ³ or less, and excellent solvent resistance is obtained. You can see that
FIG. 2 shows the relationship between the viscosity average molecular weight of the binder resin and ozone resistance. The horizontal axis of FIG. 2 indicates the viscosity average molecular weight of the binder resin, and the vertical axis indicates the amount of change in the charging potential obtained by the ozone resistance evaluation described later. The ozone resistance is better as the amount of change in the charging potential is smaller. However, if the absolute value of the amount of change in the charging potential is 145 V or less, it is possible to provide a photoconductor that does not cause defects in the image. Therefore, as shown in FIG. 2, the higher the viscosity average molecular weight, the lower the ozone resistance. If the viscosity average molecular weight of the binder resin is in the range of 80,000 or less, the amount of change in the charging potential is 141 V or less. It can be seen that it exhibits excellent ozone resistance.
That is, from FIG. 1 and FIG. 2, the electrophotographic photosensitive member for wet development includes a binder resin having a viscosity average molecular weight in the range of 60,000 to 80,000, thereby being excellent in solvent resistance and ozone resistance. It is understood that an electrophotographic photoreceptor for wet development can be provided.

(2) -2 types Further, as such a polycarbonate resin, various polycarbonate resins conventionally used in electrophotographic photoreceptors for wet development can be used, for example, bisphenol Z type, bisphenol ZC type, Examples thereof include polycarbonate resins such as bisphenol C type and bisphenol A type.
Furthermore, it is preferable to use a polycarbonate resin represented by the following general formula (1) as the binder resin.
This is because a polycarbonate resin having such a structure 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-mentioned hydrocarbon solvent is reduced, and the change in the appearance of the surface of the photoreceptor layer is reduced over a long period of time.

(R ¹ , R ² , R ³ and R ⁴ in the general formula (1) are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon X is an aryl group of 6 to 30, and X is —O—, —S—, —CO—, —COO—, — (CH ₂ ) ₂ —, —SO—, —SO ₂ —, —CR ⁵ R ^6- , —SiR ⁵ R ⁶ —, or —SiR ⁵ R ⁶ —O— (R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, substituted Alternatively, an unsubstituted aryl group having 6 to 30 carbon atoms, a trifluoromethyl group, or R ⁵ and R ⁶ may form a ring and may have an alkyl group having 1 to 7 carbon atoms as a substituent. 5-12 cycloalkylidene) and Y is a single bond, —O—, or —CO—.

  It is also preferable to use a resin other than the polycarbonate resin in combination. For example, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer Polymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer, alkyd resin, polyamide resin, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, Resin such as thermoplastic resin such as polyether resin, silicone resin, epoxy resin, phenol resin, urea resin, melamine resin, other cross-linkable thermosetting resin, epoxy acrylate, urethane acrylate, etc. Possible it is.

(2) -3 I / O Value Further, as the binder resin, it is preferable to use a polycarbonate resin having an I / O value (inorganic value / organic value) of 0.38 or more.
This is because the polycarbonate resin having such an I / O value can further improve the solvent resistance of the organic photoreceptor. However, when the value of the I / O value becomes excessively large, the solubility in the solvent used when manufacturing the photoreceptor may be lowered.
Accordingly, the I / O value of the binder resin is more preferably set to a value within the range of 0.38 to 1.7.

  Here, the inorganic value (I value) and the organic value (O value) used in the present invention, and the I / O value that is the ratio thereof are values that treat the polarity of various organic compounds in an organic concept. . For example, KUMAMOTO PHARMACEUTICAL BULLETIN, No. 1, No. 1-16 (1954); Area of Chemistry, Vol. 11, No. 10, 719-725 (1957); Fragrance Journal, No. 34, No. 97 ˜111 pages (1979); Fragrance Journal, No. 50, pp. 79-82 (1981); and the like, and as a reference value, one carbon (C) is organic 20 It is stipulated. On the other hand, the inorganic and organic values of typical polar groups are determined as shown in Table 1. Based on Table 1, etc., the sum of inorganic values of various polar groups contained in the compound (I value) And the sum (O value) of the organic value, and the ratio (I / O value) between the sum of the inorganic value and the sum of the organic value is calculated to obtain the I / O value. is there.

That is, the concept of the I / O value will be described in more detail. The properties of a compound are divided into an organic group representing a covalent bond and an inorganic group representing an ionic bond. Each point on the orthogonal coordinates named inorganic axis is shown.
In this case, the inorganic value (I value) is a value obtained by quantifying the magnitude of the influence on the boiling point of various substituents and bonds of the organic compound based on the hydroxyl group. Specifically, when the distance between the boiling point curve of the linear alcohol and the boiling point curve of the linear paraffin is about 100 ° C., the influence of one hydroxyl group is set to 100 as a numerical value. Based on this numerical value, the value obtained by quantifying the influence of various substituents or various bonds on the boiling point is the inorganic value of the substituent that the organic compound has. For example, the inorganic value of the —COOH group is 150, and the inorganic value of the double bond is 2. Therefore, the inorganic value of a certain organic compound means the sum of inorganic values such as various substituents and bonds of the compound.

On the other hand, the organic value (O value) is determined based on the influence of the methylene group in the molecule as a unit and the boiling point of the carbon atom representing the methylene group. That is, since the average value of the boiling point rise is 20 ° C. when adding one carbon in the vicinity of 5 to 10 carbon atoms of the linear saturated hydrocarbon, the organic value of one carbon atom is set to 20 on the basis of this. A value obtained by quantifying the influence of various substituents and bonds on the boiling point based on this value is an organic value. For example, the organic value of a nitro group (—NO ₂ ) is 70. Accordingly, the organic value of a certain organic compound means the sum of organic values such as various substituents and bonds of the compound.
Therefore, the calculated I / O value indicates that the closer the value is to 0, the greater the organicity, and the nonpolar (hydrophobic) organic compound. The larger the value, the greater the inorganicity, and the polar (hydrophilic) ) Organic compound.

As an example, the I / O value of the binder resin (Resin-A) represented by the formula (3) described later can be calculated as follows.
That is, this compound has 16.4 carbon atoms (organic 20), 0.85 tert branches (organic-20) in the 2-butylene group, and the organic value is 20 ×. 16.4-20 × 0.85 = 311 In addition, it has two benzene rings (inorganic 15) and one carbonate bond (—O—COO—), and the inorganic value is 15 × 2 + 80 = 110. Therefore, the I / O value of such a compound is 110/311 = 0.3537.
Therefore, the calculated I / O value indicates that the closer the value is to 0, the greater the organicity, and the nonpolar (hydrophobic) organic compound. The larger the value, the greater the inorganicity, and the polar (hydrophilic) ) Organic compound.

(2) -4 Specific Example Specific examples of the polycarbonate resin include compounds (Resin-A to D) represented by the following formulas (3) to (6).

(3) Hole Transfer Agent (3) -1 Type The type of hole transfer agent is not particularly limited, and a conventionally known hole transfer agent can be used. 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, isoxazole compounds Thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and nitrogen-containing cyclic compounds such as triazole compounds, and condensed polycyclic compounds.

Moreover, as a hole transport agent, it is preferable that the amine structure represented by General formula (2) is included in a molecular terminal, for example.
More specifically, it is preferable to use a stilbene compound containing an enamine structure represented by the following general formula (7) or a stilbene compound containing a triphenylamine structure represented by the following general formula (8).
The reason for this is that by using a stilbene compound having a specific enamine structure or triphenylamine structure introduced at a predetermined position in the molecule, the solvent resistance to hydrocarbon solvents such as 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.

(In the general formula (7), A is a divalent or trivalent organic group, and a plurality of R ^{12 to} R ¹⁷ are each independently a hydrogen atom, a halogen atom, or a substituted or unsubstituted carbon number. An alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted aryl substituted alkenyl group having 2 to 30 carbon atoms A substituted or unsubstituted condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, or a hydrocarbon group that may form a ring structure by bonding or condensing at least two of R ^{12 to} R ^17. In addition, the repetition number r is an integer of 2 or 3.)

(In the general formula (8), A is a divalent or trivalent organic group, and a plurality of R ^{18 to} R ²⁴ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted carbon number. An alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted aryl substituted alkenyl group having 2 to 30 carbon atoms A substituted or unsubstituted condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, or a hydrocarbon group that may form a ring structure by bonding or condensing at least two of R ^{18 to} R ^24. In addition, the repetition number r is an integer of 2 or 3.)

Moreover, it is preferable that the molecular weight (Mw) of the positive hole transport agent to be used shall be 900 or more.
The reason for this is that if the molecular weight is at least such a value, the compatibility with a specific binder resin will be good, and the elution amount of the hole transport agent, etc. into the developer will be reduced, and the This is because it is possible to provide an electrophotographic photoreceptor for wet development that is excellent in solvent property and durability.
Note that the molecular weight of the hole transport agent can be calculated based on the structural formula, or can be measured by a mass spectrum obtained by a mass spectrometer.

(3) -2 Specific Example Here, as an example of the stilbene derivatives represented by the general formulas (7) and (8), stilbene derivatives (HTM-A to E) represented by the following formulas (9) to (13) ).

(3) -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 added amount of the hole transport agent 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) Electron Transfer Agent (4) -1 Type The electron transfer agent suitable for the wet electrophotographic photoreceptor of the present invention is a value obtained by dividing the inorganic value (I value) by the organic value (O value) (I / (O value) is preferably 0.5 or more.
The reason for this is that by limiting the I / O value of the electron transfer agent to a specific range, the inorganicity of the electron transfer agent can be increased, and excellent durability can be obtained for a hydrocarbon solvent that is an organic solvent. It is.

Moreover, as a kind of electron transport agent, it is preferable that a naphthoquinone derivative or an azoquinone derivative is included.
The reason for this is that by using a specific compound as an electron transporting agent, the electron accepting property is excellent, and since the compatibility with the charge generating agent is excellent, the sensitivity property and the solvent resistance are excellent. This is because an electrophotographic photoreceptor for wet development can be provided.

In addition, the specific electron transport agent may be at least one nitro group (—NO ₂ ), a substituted carboxyl group (—COOR (where R is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon number). 6-30 aryl groups)), and substituted carbonyl groups (-COR (R is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms)) It is preferable.
The reason for this is that an electrophotographic photosensitive member for wet development having excellent solvent resistance can be provided when the electron transfer agent used has a specific substituent.

Moreover, it is also preferable to use a conventionally known electron transport agent alone or 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.
In particular, among these electron transfer agents, it is preferable to include at least one compound selected from the group consisting of naphthalenecarboxylic acid derivatives, naphthoquinone derivatives, and azoquinone derivatives.
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.

  More specifically, naphthalenecarboxylic acid derivatives, naphthoquinone derivatives, azoquinone derivatives (ETM-A to D) represented by the following formulas (14) to (17) are preferable.

(4) -2 Addition amount In constituting the electrophotographic photosensitive member for wet development, the addition amount of the electron transport agent is set to a value within the range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin. It is preferable to do.
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, it is more preferable to set the addition amount of the electron transfer agent to a value within the range of 20 to 80 parts by weight.

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 later. 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.

(5) Charge generator (5) -1 type As the charge generator used in the electrophotographic photoreceptor of the present invention, metal-free phthalocyanine (τ type or x type), titanyl phthalocyanine (α type or Y type), It is preferable to include at least one compound selected from the group consisting of hydroxygallium phthalocyanine (type V) and chlorogallium phthalocyanine (type II).
The reason for this is that by specifying the type of charge generating agent, an electrophotographic photosensitive member for wet development that has better sensitivity characteristics, electrical characteristics, stability, etc. when a hole transporting agent and an electron transporting agent are used in combination. This is because it can be provided.

(5) -2 Specific Example Among these charge generators, it is more preferable to use phthalocyanine pigments (CGM-A to CGM-D) represented by the following formulas (18) to (21). preferable.

  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.

(5) -3 Addition amount The addition amount of the charge generator is preferably set to a value within the range of 0.2 to 40 parts by weight with respect to 100 parts by weight of the binder resin.
The reason for this is that when the added amount of the plurality of charge generating agents is less than 0.2 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 reduced. This is because it cannot be improved. On the other hand, when the added amount of the plurality of charge generating agents exceeds 40 parts by weight, the absorption coefficient for light having an absorption wavelength in the red and infrared to near infrared regions decreases, and the sensitivity of the photoreceptor, This is because electrical characteristics, stability, and the like may be reduced accordingly.
Therefore, it is more preferable to set the addition amount of the charge generating agent to a value within the range of 0.5 to 20 parts by weight.

(6) Additive In addition to the above-mentioned components, the photoreceptor layer has various conventionally known additives such as an antioxidant, a radical scavenger, a singlet as long as it does not adversely affect the electrophotographic characteristics. Deterioration inhibitors such as quenchers and ultraviolet 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) Structure The thickness of the photoreceptor layer in the single-layer photoreceptor is usually a value in the range of 5 to 100 μm, preferably a value in the range of 10 to 50 μm.
As the conductive 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, titanium, nickel, palladium, indium, stainless steel, brass, etc., plastic materials on which these metals are vapor-deposited or laminated, carbon black and other conductive fine particles, plastic materials, aluminum iodide And glass coated with 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. When the photoreceptor layer is formed by a coating method, a known method such as a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic wave is used together with an appropriate charge generating agent, charge transport agent, binder resin and the like in an appropriate solvent. A dispersion liquid may be prepared by dispersing and mixing using a disperser or the like, and this may be applied and dried by a known means.

  In addition, as shown in FIG. 3B, a single layer type photoreceptor is provided with a barrier layer 16 between the conductive substrate 12 and the photosensitive layer 14 in a range that does not impair the characteristics of the photoreceptor. A layer mold 10 'may be used. Further, as shown in FIG. 3C, a single layer type 10 ″ in which a protective layer 18 is formed on the surface of the photosensitive layer 14 may be used.

(8) Manufacturing method Various organic solvents can be used as a solvent for preparing the dispersion. For example, alcohols such as methanol, ethanol, isopropanol, and butanol; aliphatic systems such as n-hexane, octane, and cyclohexane Hydrocarbons: aromatic hydrocarbons such as benzene, toluene, xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene; dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dioxane, Ethers such as dioxolane; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformaldehyde, dimethylform Amides, dimethyl sulfoxide and the like. These solvents are used alone or in combination of two or more.
Further, a surfactant, a leveling agent or the like may be used in order to improve the dispersibility of the charge transport agent or the charge generator and the smoothness of the surface of the photoreceptor layer.

2. Laminated Photoreceptor (1) Basic Structure As shown in FIG. 4A, the laminated photoreceptor 20 generates a charge containing a charge generating agent on a conductive substrate 12 by means of vapor deposition or coating. The layer 24 is formed, and then the charge generation layer 24 is coated with a coating liquid containing at least one kind of a hole transport agent and a binder resin, and dried to form the charge transport layer 22. Is done.
In contrast to the above structure, as shown in FIG. 4B, a stacked type 20 ′ in which the charge transport layer 22 is formed on the conductive substrate 12 and the charge generation layer 24 is formed thereon may be used.

However, since the charge generation layer 24 is much thinner than the charge transport layer 22, the charge transport layer 22 is protected on the charge generation layer 24 as shown in FIG. It is more preferable to form
The charge generating agent, hole transporting agent, electron transporting agent, binder and the like can be basically the same as those of the single-layer type photoreceptor. However, in the case of a multilayer photoreceptor, the amount of charge generator added may be set to a value within the range of 0.5 to 150 parts by weight with respect to 100 parts by weight of the binder resin constituting the charge generation layer. preferable.

In addition, a positive or negative charge type is selected depending on the formation order of the charge generation layer and the charge transport layer and the kind of the charge transport agent used in the charge transport layer. For example, when a charge generation layer is formed on a conductive substrate and a charge transport layer is formed thereon, a hole transport agent such as a stilbene derivative is used as the charge transport agent in the charge transport layer. The photoreceptor is of a negative charge type. In this case, the charge generation layer may contain an electron transport agent. In the case of a multilayer electrophotographic photoreceptor, the residual potential of the photoreceptor 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.

[Second Embodiment]
The second embodiment includes the electrophotographic photosensitive member for wet development of the first embodiment (hereinafter sometimes simply referred to as a photosensitive member), and around the electrophotographic photosensitive member for wet development. An image for wet development, wherein a charging step, an exposure step, a development step, and a transfer step are arranged, and in the development step, an image is formed using a liquid developer in which a toner is dispersed in a hydrocarbon solvent. Forming device. In this example of the image forming apparatus for wet development, a case where a single layer type photoreceptor is used as the electrophotographic photoreceptor will be described.
That is, as shown in FIG. 5, the image forming apparatus for wet development includes a charger 32 for performing the charging process and an exposure light source for performing the exposure process around the electrophotographic photosensitive member for wet development. 33. It is preferable that at least a wet developing device 34 for performing the developing process and a transfer device 35 for performing the transferring process are provided.
The photoconductor 31 rotates at a constant speed in the direction of the arrow, and the electrophotographic process is performed on the surface of the photoconductor 31 in the following order. More specifically, the photosensitive member 31 is entirely charged by the charger 32, and then the print pattern is exposed by the exposure light source 33. Next, the toner is developed by the wet developing device 34 corresponding to the print pattern, and the toner is transferred onto the transfer material (paper) 36 by the transfer device 35. Finally, excess toner remaining on the photoconductor 31 is scraped off by the cleaning blade 37 and the photoconductor 31 is neutralized by the neutralizing light source 38.

Here, the liquid developer 34a in which the toner is dispersed is conveyed by the developing roller 34b, and the toner is attracted onto the surface of the photoconductor 31 by applying a predetermined developing bias, and developed on the photoconductor 31. Will be. Moreover, it is preferable to make the solid content concentration in the liquid developer 34a into a value within the range of 5 to 25% by weight, for example. Further, as the liquid (toner dispersion solvent) used in the liquid developer 34a, a hydrocarbon solvent or a silicone oil is preferably used.
Then, by using a hole transport material having a specific amine structure in the photoreceptor 31, a single layer type electrophotographic photoreceptor for wet development having excellent solvent resistance and sensitivity characteristics can be obtained. Excellent image characteristics can be maintained over time.

[Example 1]
(1) Preparation of electrophotographic photosensitive member for wet development As a charge generator, 4 parts by weight of X-type metal-free phthalocyanine (CGM-A) represented by the formula (18) and a hole transporting agent are used. 40 parts by weight of a stilbene derivative (HTM-A) represented by the formula (14), and 50 parts by weight of a naphthalene derivative (ETM-A) represented by the formula (14) as a binder resin. 100 parts by weight of a polycarbonate resin (Resin-A) having a viscosity average molecular weight of 60,500, KF-96-50CS which is a dimethyl silicone oil as a leveling agent. After containing 0.1 part by weight (manufactured by Shin-Etsu Chemical Co., Ltd.) and 750 parts by weight of tetrahydrofuran as a solvent, it was mixed and dispersed with an ultrasonic disperser for 1 hour to prepare a coating solution. .
The obtained coating solution was applied by dip coating on a conductive base material (anodized aluminum base tube) having a diameter of 30 mm and a length of 254 mm. Thereafter, it was dried with hot air at 140 ° C. for 20 minutes to obtain an electrophotographic photoreceptor for wet development having a single-layer photoreceptor layer with a thickness of 20 μm.

(2) Evaluation (2) -1 Solvent resistance evaluation The obtained single layer type electrophotographic photosensitive member for wet development is soaked with Isopar L (used as a developer for wet development so that the entire surface of the photosensitive layer is immersed. (Isoparaffin solvent, manufactured by Exxon Chemical Co.) was immersed in 500 ml under the conditions of a temperature of 25 ° C. and 200 hours. On the other hand, the concentration of the hole transport agent was changed and dissolved in Isopar L. In this state, the absorbance at the ultraviolet absorption peak wavelength was measured, and a concentration-absorbance calibration curve for the hole transport agent was prepared in advance. Next, the electrophotographic photosensitive member for wet development immersed in Isopar L is subjected to ultraviolet absorption measurement, and the amount of elution of the hole transport agent is calculated from the absorbance at the ultraviolet absorption peak wavelength of the hole transport agent in light of the calibration curve. did. The obtained results are shown in Table 2.

(2) -2 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 2.
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.

(2) -3 Evaluation of ozone resistance The obtained electrophotographic photosensitive member for wet development was subjected to an ozone exposure test, and then the light potential was measured. In other words, it was mounted on a digital copying machine “Creage 7340” (manufactured by Kyocera Mita Co., Ltd.), charged to 800 V, and the initial charging potential (V ₀ ) was measured. Next, the electrophotographic photosensitive member for wet development was removed from the digital copying machine, and left in a dark place where the ozone concentration was adjusted to 10 ppm at room temperature for 8 hours. Next, after exposure was completed and 1 hour passed, the electrophotographic photosensitive member for wet development was again mounted on the digital copying machine, and the surface potential after 60 seconds from the start of charging was measured. (V _E ). A value obtained by subtracting the initial charging potential (V ₀ ) from the surface potential after exposure (V _E ) was defined as a change in charging position (V _E −V ₀ ) in the ozone resistance evaluation.

[Examples 2 to 4]
In Examples 2 to 4, the influence of the viscosity average molecular weight and the kind of the polycarbonate resin, which is the binder resin of the electrophotographic photosensitive member for wet development, were examined.
That is, in Example 2, instead of the polycarbonate resin (Resin-A) having a viscosity average molecular weight of 60,500 used in Example 1, the same type of polycarbonate having a viscosity average molecular weight of 71,500 was used. Resin was used, and in Example 3, electrophotographic photoconductors for wet development were prepared in the same manner as in Example 1 except that polycarbonate resins of the same type and having a viscosity average molecular weight of 79,000 were used. And evaluated.
Moreover, in Example 4, the viscosity average molecular weight represented by Formula (4) is 60,500 instead of the polycarbonate resin (Resin-A) whose viscosity average molecular weight is 60,500 used in Example 1. Except that a certain polycarbonate resin (Resin-B) was used, an electrophotographic photoreceptor for wet development was prepared and evaluated in the same manner as in Example 1.

[Examples 5 to 9]
In Examples 5 to 9, the influence of the type of the hole transfer agent in the electrophotographic photoreceptor for wet development was examined.
That is, in Example 5, instead of the hole transport agent (HTM-A) used in Example 1, the hole transport agent (HTM-B) represented by the formula (10) was used, and Example 6 was used. In Example 7, the hole transporting agent (HTM-C) represented by the formula (11) is used, and in Example 7, the hole transporting agent (HTM-D) represented by the formula (12) is used. In Example 8, the hole transport agent (HTM-E) represented by the formula (13) was used, and in Example 9, the hole transport agent (HTM-F) represented by the following formula (22) was used. Except for the use, an electrophotographic photoreceptor for wet development was prepared and evaluated in the same manner as in Example 1.

[Example 10]
In Example 10, the influence of the type of the charge generating agent in the electrophotographic photoreceptor for wet development was examined.
That is, in Example 10, instead of the charge generator (CGM-A) used in Example 1, the charge generator (CGM-B) represented by the formula (19) was used. In the same manner as in Example 1, electrophotographic photoreceptors for wet development were prepared and evaluated.

[Examples 11 to 13]
In Examples 11 to 13, the influence of the type of the electron transfer agent in the electrophotographic photosensitive member for wet development was examined.
That is, in Example 11, instead of the electron transfer agent (ETM-A) used in Example 1, an electron transfer agent (ETM-B) represented by the formula (15) was used, and in Example 12, In Example 13, except that the electron transfer agent (ETM-D) represented by the formula (17) was used in Example 13, the electron transfer agent (ETM-C) represented by the formula (16) was used. In the same manner as in Example 1, electrophotographic photoreceptors for wet development were prepared and evaluated.

[Examples 14 to 16]
In Examples 14 to 16, the influence of the viscosity average molecular weight and the kind of the polycarbonate resin, which is the binder resin of the electrophotographic photosensitive member for wet development, were examined.
That is, in Example 14, instead of the polycarbonate resin (Resin-A) having a viscosity average molecular weight of 60,500 used in Example 1, the viscosity average molecular weight represented by the formula (4) is 60,200. Using a certain polycarbonate resin (Resin-B), in Example 15, using a polycarbonate resin (Resin-C) having a viscosity average molecular weight of 59,500 represented by the formula (5), in Example 16, An electrophotographic photoreceptor for wet development was prepared and evaluated in the same manner as in Example 1 except that the polycarbonate resin (Resin-D) having a viscosity average molecular weight of 60,700 represented by the formula (6) was used. did.

[Comparative Examples 1-4]
Moreover, in the comparative example 1, instead of the polycarbonate resin (Resin-A) whose viscosity average molecular weight is 60,500 used in Example 1, it is the same kind and the polycarbonate resin whose viscosity average molecular weight is 50,000. In Comparative Example 2, an electrophotographic photosensitive member for wet development was prepared in the same manner as in Example 1 except that the same type of polycarbonate resin having a viscosity average molecular weight of 29,500 was used. ,evaluated.
In Comparative Example 3, a polycarbonate resin having the same type as in Example 1 and having a viscosity average molecular weight of 85,000 is used. In Comparative Example 2, the same type as in Example 1 and having a viscosity average molecular weight of Except for using the polycarbonate resin of 92,500, each electrophotographic photosensitive member 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 polycarbonate resin having a specific molecular weight as the binder resin, the electrophotographic photoreceptor for wet development having excellent solvent resistance and ozone resistance and the same are provided. An image forming apparatus for wet development can be obtained.
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.

It is a figure provided in order to demonstrate the influence with respect to solvent resistance of the viscosity average molecular weight of binder resin in the electrophotographic photoreceptor for wet development. It is a figure provided in order to demonstrate the influence with respect to ozone resistance of the viscosity average molecular weight of binder resin in the electrophotographic photoreceptor for wet development. (A)-(c) is a figure provided in order to demonstrate the basic structure and deformation | transformation structure of a single layer type photoreceptor. (A)-(b) is a figure provided in order to demonstrate the basic structure and deformation | transformation structure of a laminated type photoreceptor. Supplied to explain an image forming apparatus provided with an electrophotographic photosensitive member for wet development

Explanation of symbols

10: Single layer type photoreceptor 12: Conductive substrate 14: Photosensitive layer 16: Barrier layer 18: Protective layer 20: Multilayer type photoreceptor 22: Charge transport layer 24: Charge generation layer 31: Photoconductor 32: Charger 33: Exposure light source 34: wet developing device 34a: liquid developer 34b: developing roller 35: transfer device 36: transfer material 37: cleaning blade 38: static elimination light source 39: probe

Claims (10)

An electrophotographic photoreceptor for wet development comprising a photoreceptor layer comprising a binder resin, a hole transport agent, an electron transport agent, and a charge generator,
An electrophotographic photosensitive member for wet development, comprising a polycarbonate resin as the binder resin and a viscosity average molecular weight of the polycarbonate resin within a range of 60,000 to 80,000. The electrophotographic photoreceptor for wet development according to claim 1, wherein the binder resin contains a polycarbonate resin represented by the following general formula (1).

(R ¹ , R ² , R ³ and R ⁴ in the general formula (1) are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon X is an aryl group of 6 to 30, and X is —O—, —S—, —CO—, —COO—, — (CH ₂ ) ₂ —, —SO—, —SO ₂ —, —CR ⁵ R ^6- , —SiR ⁵ R ⁶ —, or —SiR ⁵ R ⁶ —O— (R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, substituted Alternatively, an unsubstituted aryl group having 6 to 30 carbon atoms, a trifluoromethyl group, or R ⁵ and R ⁶ may form a ring and may have an alkyl group having 1 to 7 carbon atoms as a substituent. 5-12 cycloalkylidene) and Y is a single bond, —O—, or —CO—. The electrophotographic photosensitive member for wet development according to claim 1 or 2, wherein the hole transport agent contains an amine structure represented by the following general formula (2).

(Formula (2) R ⁷ ~R ¹¹ in are each independently respectively and independently, a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted A substituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted aryl substituted alkenyl group having 6 to 30 carbon atoms, a substituted or unsubstituted condensed polycyclic hydrocarbon group having 10 to 30 carbon atoms, or R ⁷ to At least two or more of R ¹¹ are hydrocarbon groups that may be bonded or condensed to form a ring structure.)   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. An electrophotographic photoreceptor for wet development.   The electrophotographic photosensitive member for wet development according to any one of claims 1 to 4, wherein the hole transport agent has a molecular weight of 900 or more.   6. The addition amount of the electron transfer agent is set to a value within a range of 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin. 6. An electrophotographic photoreceptor for wet development.   7. The binder resin according to claim 1, comprising a polycarbonate resin having an I / O value (inorganic value / organic value) of 0.38 or more. An electrophotographic photoreceptor for wet development.   The amount of the charge generating agent added is set to a value within a range of 0.2 to 40 parts by weight with respect to 100 parts by weight of the binder resin. The electrophotographic photoreceptor for wet development as described.   9. The organic photoreceptor according to claim 1, wherein the organic photoreceptor is a single layer type containing at least a charge generator, a hole transport agent, an electron transport agent and a binder resin in the same layer on a conductive substrate. The electrophotographic photoreceptor for wet development according to any one of the above. A liquid comprising an electrophotographic photosensitive member for wet development, at least charging, exposing, developing, and transferring steps around the electrophotographic photosensitive member for wet development, and a toner dispersed in a hydrocarbon solvent in the developing step In an image forming apparatus that forms an image using a developer,
The electrophotographic photoreceptor for wet development includes a photoreceptor layer containing at least a binder resin, a hole transport agent, an electron transport agent, and a charge generator on a conductive substrate, and the binder resin. The image forming apparatus for wet development is characterized in that the viscosity average molecular weight is a value in the range of 60,000 to 80,000.

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