JP2006284680A - 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 wear resistance by using a specified kind of a 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 photoreceptor contains a polycarbonate resin expressed by general formula (1) as the binder resin, and the molecular weight of the hole transport agent is specified to 900 or more. 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, a halogen atom, a substituted or unsubstituted 1-12C alkyl group, a substituted or unsubstituted 1-12C halogenated alkyl group, a substituted or unsubstituted 6-30C aryl group, or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member for wet development and an image forming apparatus for wet development including the same, and more particularly, to an electrophotographic photosensitive member for wet development using a specific polycarbonate resin and a hole transport agent having a specific molecular weight. The present invention relates to a body and an image forming apparatus for wet development including the same.

  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.

  Among such organic photoreceptor materials, a polycarbonate resin represented by the following general formula (29) is used as a binder resin, which is excellent in wear resistance and scratch resistance and can maintain electrophotographic identification for a long time. An electrophotographic photoreceptor used is disclosed (for example, Patent Document 1).

(In the general formula (29), R ²⁵ represents a hydrogen atom or a methyl group, and a plurality of R ²⁶ are each independently a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, substituted Or a monovalent group selected from the group of an unsubstituted aryl group, an aryl group-substituted alkenyl group and a condensed polycyclic hydrocarbon group, and the repeating number r is an integer of 0 to 4.)

  Further, among organic photoreceptor materials, electrophotographic photoreceptors for wet development using a polycarbonate resin represented by the following general formula (30) as a binder resin having solvent resistance are disclosed (for example, patents). Reference 2).

(Formula (30) in the R ²⁷ and R ²⁸ are each independently is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)
JP-A-2001-255664 (Claims) JP-A-2002-116560 (Claims)

However, although the polycarbonate resin described in Patent Document 1 discloses use as an electrophotographic photoreceptor for wet development, the polycarbonate resin represented by the general formula (29) is used as an electrophotographic photoreceptor for wet development. When used, the abrasion resistance is excellent, but the solvent resistance is insufficient, so that there is a problem that the electrical characteristics cannot be sufficiently exhibited.
Further, the polycarbonate resin described in Patent Document 2 is used for electrophotographic photoreceptors for wet development and has a predetermined solvent resistance, but has a poor solvent resistance when used for a long time. Since this was sufficient, there was a problem that the amount of elution of the charge transfer agent and the like was large, and the sensitivity characteristics could not be fully exhibited.

Therefore, the present inventors use a specific polycarbonate resin and a hole transporting agent having a specific molecular weight in combination, so that the compatibility between the binder resin and the hole transporting agent is excellent. It has been found that the solvent resistance and sensitivity characteristics are improved even when used for a long time. In addition, by using a specific polycarbonate resin, excellent wear resistance can be obtained, and further, by using a hole transport agent having a specific molecular weight, the charge injection property is excellent, so the sensitivity characteristics are improved. As a result, the present invention has been completed.
That is, an object of the present invention is to provide an electrophotographic photosensitive member for wet development excellent in solvent resistance, abrasion resistance and sensitivity characteristics even when used for a long time, and such an electrophotographic photosensitive member for wet development. The present invention provides an image forming apparatus including the above.

  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, and a charge generator, wherein the binder resin has the following general formula ( An electrophotographic photoreceptor for wet development containing the polycarbonate resin represented by 1) is provided, and the above-described problems 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 alkenyl group having 2 to 30 carbon atoms, or carbon (It is a condensed polycyclic hydrocarbon group having a number of 3 to 30.)

  Further, in constituting the electrophotographic photosensitive member for wet development of the present invention, the amount of the hole transport agent added 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 photoreceptor for wet development of the present invention, the hole transport agent preferably contains an amine structure represented by the following general formula (2).

(A in the general formula (2) is a divalent or trivalent organic group, and a plurality of R ^{7 to} R ¹¹ are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted group having 1 to 20 carbon atoms. An alkyl group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, or R ^{7 to} R ^{11 is} a hydrocarbon group that may be bonded or condensed to form a ring structure, and the repeating number p is an integer of 2 or 3.)

  Further, in constituting the electrophotographic photosensitive member for wet development of the present invention, it further contains an electron transport agent, and the addition amount of the electron transport agent is 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin. A value within the range is preferable.

  In constituting the electrophotographic photosensitive member for wet development according to the present invention, the molecular weight of the electron transfer agent is preferably set to a value of 600 or more.

  In constituting the electrophotographic photosensitive member for wet development of the present invention, the I / O value of the electron transport agent is preferably set to a value of 0.6 or more.

  Further, in constituting the electrophotographic photoreceptor for wet development according to the present invention, the amount of the charge generator added may be 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. preferable.

  In constructing the electrophotographic photoreceptor for wet development according to the present invention, as a charge generator, 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).

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

  In constructing the electrophotographic photoreceptor for wet development of the present invention, the photoreceptor layer is preferably a single layer type.

  Another aspect of the present invention includes any one of the electrophotographic photoconductors for wet development described above, and a charging step, an exposure step, a development step, and a transfer step around the electrophotographic photoconductor for wet development. This is an image forming apparatus for wet development in which parts for execution are arranged and image formation is performed using a liquid developer in which a toner is dispersed in a hydrocarbon solvent in a development process.

According to the electrophotographic photoreceptor for wet development of the present invention, when a specific polycarbonate resin and a hole transport agent having a specific molecular weight are used in combination, the electrophotographic photoreceptor for wet development is used for a long time. Even so, excellent solvent resistance, abrasion resistance and sensitivity characteristics can be obtained.
That is, the specific binder resin and the specific hole transport agent are excellent in compatibility, and thus are uniformly dispersed in the photoreceptor phase. For this reason, the electrophotographic photoreceptor for wet development is excellent in solvent resistance and excellent in sensitivity characteristics even when it is used for a long time. In addition, by using a specific polycarbonate resin, it is possible to obtain excellent wear resistance because the hardness is high, and further, because the molecular weight of the hole transport agent is 900 or more, the charge injection property is excellent. Excellent sensitivity characteristics can be obtained.

  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.

  In addition, according to the electrophotographic photoreceptor for wet development of the present invention, an electron transport agent is further contained, and the amount of the electron transport agent added is limited to a value within the range of a predetermined part by weight. Therefore, it is possible to provide an electrophotographic photosensitive member for wet development that can effectively prevent the formation of the toner and that has excellent sensitivity characteristics.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, it is possible to provide an electrophotographic photoreceptor for wet development further excellent in sensitivity characteristics by limiting the molecular weight of the electron transfer agent to a predetermined range. .
That is, by using a compound having a molecular weight limited to a predetermined range as an electron transport agent in an electrophotographic photosensitive member for wet development, electrons can be efficiently transferred between the charge generator and the hole transport agent. Therefore, further excellent sensitivity characteristics can be obtained.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, the value (I / O value) obtained by dividing the inorganic value (I value) of the electron transport agent by the organic value (O value) is limited to a predetermined range. By doing so, the solubility with respect to the solvent used at the time of manufacture and a binder resin increases, and also compatibility with a specific hole transport agent can be improved.
Therefore, by including such an electron transport agent in the electrophotographic photoreceptor for wet development, not only the manufacture of the photoreceptor is facilitated, but also the charge transport efficiency is improved, so that the sensitivity characteristics can be excellent. Furthermore, by limiting the I / O value to a predetermined range as described above, it is possible to provide an electrophotographic photosensitive member for wet development having excellent solvent resistance against hydrocarbon solvents.

  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 further the red region in visible light, The effect of increasing the absorption coefficient for light having a wavelength in the near infrared region or in the infrared region can be maintained.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, by specifying the type of the charge generating agent, when the hole transporting agent and the electron transporting agent are used in combination, the sensitivity characteristics, electrical characteristics and stability are further improved. Can be excellent.
Therefore, by including such a charge generating agent in the electrophotographic photoreceptor for wet development, it is possible to provide an electrophotographic photoreceptor for wet development that maintains predetermined sensitivity characteristics even when used for a long time.

  In addition, according to the electrophotographic photoreceptor for wet development of the present invention, the solvent resistance during development can be determined with high accuracy by limiting the elution amount of the hole transport agent to a specific range. For example, it is possible to accurately estimate the solvent resistance when forming an image of 100,000 sheets of A4 paper by a 2000 hour immersion test.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, the construction and production are facilitated by making the photoreceptor layer a single layer type.
Therefore, since the electrophotographic photoreceptor for wet development is a single layer type, an electrophotographic photoreceptor for wet development having a predetermined sensitivity when used for a long time can be efficiently produced.

According to the image forming apparatus for wet development of the present invention, a hydrocarbon used as a wet developer by providing any of the electrophotographic photoreceptors for wet development described above in the electrophotographic photoreceptor for wet development. Even when used in a solvent for a long time, an image forming apparatus provided with an electrophotographic photosensitive member for wet development that has a small amount of elution of a charge transfer agent and the like and has excellent sensitivity characteristics can be provided. .
Therefore, by providing such an image forming apparatus for wet development with such an electrophotographic photoreceptor for wet development, a clear image can be provided even when used for a long time.

  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]
The first embodiment is an electrophotographic photosensitive member for wet development provided with a photoreceptor layer containing a binder resin, a hole transport agent, and a charge generator, and the binder resin has the following general formula: The electrophotographic photosensitive member for wet development includes a polycarbonate resin represented by (1) and a compound having a molecular weight of 900 or more as a hole transport agent. In addition, R < ¹ > -R < ⁶ > in General formula (1) is the content already demonstrated.

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. 1A, the single layer type photoreceptor 10 is obtained by providing a single photoreceptor layer 14 on a conductive substrate 12.
This photoreceptor layer includes, for example, a binder resin containing a polycarbonate resin having a structural unit represented by the general formula (1), a hole transporting agent having a molecular weight of 900 or more, a charge generating agent, and further necessary. Accordingly, it can be formed by dissolving or dispersing an electron transporting agent, a leveling agent or the like in an appropriate solvent, coating the obtained coating solution on a conductive substrate, and drying. 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.
In addition, since the obtained single layer type photoreceptor contains a polycarbonate resin having a specific structure and a hole transport agent having a specific molecular weight, it has excellent solvent resistance, wear resistance, and sensitivity characteristics. It has the feature of having.
Furthermore, when an electron transport agent is included in the photoreceptor layer of a single-layer type photoreceptor, electrons are efficiently exchanged between the charge generator and the hole transport agent, and the sensitivity and the like are more stable. The tendency to do is seen.

(2) Binder Resin (2) -1 Type As described above, as the binder resin for dispersing the charge generating agent, the polycarbonate represented by the general formula (1) is used. .
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) -2 Specific example Here, as a specific example of polycarbonate resin represented by General formula (1), the compound (Resin-AD) shown by following formula (3)-(5) is mentioned, for example. It is done.
In addition, the compound represented by Formula (5) 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 Transfer Agent (3) -1 Type As the hole transfer agent used in the electrophotographic photoreceptor for wet development of the present invention, a compound having a molecular weight of 900 or more is used.
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 photosensitive member for wet development which is excellent in solvent resistance and abrasion resistance. Moreover, since the charge injection property is excellent, an electrophotographic photoreceptor for wet development having excellent sensitivity characteristics can be provided.
The molecular weight of the hole transport agent can be calculated based on, for example, the structural formula, or can be measured using a mass spectrum obtained with a mass spectrometer.

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 transport agent, and the vertical axis shows the elution amount of the hole transport agent after immersing the multilayer electrophotographic photosensitive member for wet development in Isopar L solvent for 2000 hours. (G / cm ³ ).
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. Further, when the value of the hole transport agent is 900 or more, it can be seen that the elution amount of the hole transport agent is 1 × 10 ⁻⁶ (g / cm ³ ) or less, that is, 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 a hole transport agent, which will be described later, and the vertical axis shows a laminated electrophotographic photosensitive film for wet development measured by sensitivity evaluation described later. It shows the sensitivity change (V) of the body.
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 4 (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 does not restrict | limit especially as a kind of hole transport agent, A conventionally well-known hole transport 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, isoxazols System compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, and nitrogen-containing cyclic compounds such as triazole compounds, and condensed polycyclic compounds.

Moreover, it is preferable that the hole transport agent contains an amine structure represented by the general formula (2).
More specifically, it is preferable to use a compound containing an enamine structure represented by the following general formula (6) or a compound containing a triphenylamine structure represented by the following general formula (7).
The reason for this is that by using a compound having 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 improved. Because it can. 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 General Formula (6), A is a divalent or trivalent organic group, and the plurality of R ^{12 to} R ¹⁷ 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 in which at least two of R ^{12 to} R ¹⁷ may be bonded or condensed to form a ring structure; The repeat number q is an integer of 2 or 3.)

(In the general formula (7), A is a divalent or trivalent organic group, and the plurality of R ^{18 to} R ²⁴ 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 at least two of R ^{18 to} R ²⁴ may be bonded or condensed to form a ring structure, The repeat number q is an integer of 2 or 3.)

(3) -2 Specific Example Here, as specific examples of the hole transport agent having an amine structure represented by the general formula (2), stilbene derivatives represented by the following formulas (8) to (11) (HTM- A to D).

(3) -3 Addition Amount The addition amount of the hole transport agent is preferably 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.
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 80 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 that the added amount of the hole transport agent is set to a value within the range of 30 to 70 parts by weight with respect to 100 parts by weight of the binder resin.

(4) Electron Transfer Agent (4) -1 Type The electron transfer agent suitable for the electrophotographic photoreceptor for wet development of the present invention preferably has a molecular weight of 600 or more.
The reason for this is that by setting the molecular weight of the electron transport agent to 600 or more, as shown in FIGS. 4 and 5, the solvent resistance against hydrocarbon solvents can be improved and the elution from the photosensitive layer can be effectively suppressed. At the same time, the change in the repetitive characteristics in the photosensitive layer can be remarkably reduced.
However, when the molecular weight of the electron transport agent becomes excessively large, the dispersibility in the photosensitive layer may be lowered, or the hole transport ability may be lowered.
Therefore, the molecular weight of the electron transport agent is more preferably set to a value within the range of 600 to 2000, and further preferably set to a value within the range of 600 to 1000.
In addition, the molecular weight of the electron transport agent can be calculated based on the structural formula, or can be calculated using a mass spectrum.
In addition, the repeated change in charging potential characteristics of the obtained electrophotographic photoreceptor for wet development was measured as follows. First, using a drum sensitivity tester (manufactured by GENTEC), the potential was measured in a state of being charged so as to be 700 V to obtain an initial charging potential. Next, the entire electrophotographic photoreceptor for wet development was immersed in Isopar L (aliphatic hydrocarbon solvent) at a temperature of 25 ° C. for 200 to 2,000 hours. Thereafter, the electrophotographic photoreceptor for wet development is taken out from Isopar L, charged to 700 V, and then monochromatic light having a wavelength of 780 nm taken out from the light of the halogen lamp using a hand pulse filter (half-value width: 20 nm, light quantity) : 1.5 μJ / cm ² ) was applied to the surface of the photosensitive member, and then the entire surface of the photosensitive member was irradiated with monochromatic light of 780 nm. This charging, exposure, and charge removal steps were performed for 2400 cycles, after which the charging potential was measured and used as the charging potential after running. Then, the difference between the initial charging potential and the post-running charging potential was calculated and used as a repeated characteristic change.

The electron transporting agent preferably has a value (I / O value) obtained by dividing the inorganic value (I value) by the organic value (O value) of 0.6 or more.
The reason for this is that the dispersibility and stability of the hole transport agent are improved by the interaction with a binder resin having a specific I / O value, which will be described later. As shown in FIG. This is because the hole transport agent is less likely to elute into the system solvent.
Therefore, even when used in a wet image forming apparatus using a developing solution in which toner particles are dispersed in a hydrocarbon solvent, excellent solvent resistance and durability, as shown in FIG. Sensitivity change can be obtained.
However, when the value of the I / O value becomes excessively large, the solubility with respect to the solvent or the binder resin may decrease, and crystallization may occur, or the electrical characteristics of the photoreceptor may decrease. Therefore, the I / O value of the electron transfer agent is more preferably set to a value within the range of 0.6 to 1.7, and further preferably set to a value within the range of 0.65 to 1.6.

  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. Therefore, the organic value of a certain type of organic compound means the sum of various substituents and bonds of the compound.

Therefore, as an example, the I / O value of the naphthoquinone derivative represented by the electron transfer agent (ETM-G) represented by the formula (18) described later is calculated as follows.
That is, this compound has 23 carbon atoms (organic 20), and the organic value is 20 × 23 = 460. Further, since it has one naphthalene ring (inorganic 60), two benzene rings (inorganic 15), and three ketone groups (inorganic 65), the inorganic value is 60. X1 + 15x2 + 65x3 = 285. Therefore, the I / O value of such a compound is 285/460 = 0.6196.

In addition, the electron transfer agent is 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 to 30) aryl group)), and a substituted carbonyl group (-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)). 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 transport agents, it is preferable to include 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.

(4) -2 Specific Example Here, specific examples of the electron transport agent include naphthoquinone derivatives represented by the following formulas (12) to (18), azoquinone derivatives (ETM-A to G), and the like.

(4) -3 Addition amount The addition amount of the electron transport agent is preferably 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.
This is because when the amount of the electron 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 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, the addition amount of the electron transport agent is more preferably set to a value within the range of 20 to 80 parts by weight with respect to 100 parts by weight of the binder resin.

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 Here, specific examples of the charge generating agent include phthalocyanine pigments (CGM-A to CGM-D) represented by the following formulas (19) to (22).

  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 includes various conventionally known additives such as antioxidants, radical scavengers, singlet quenchers, ultraviolet absorbers and other deterioration inhibitors. , Softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like. 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 preferably a value in the range of 5 to 100 μm. This is because if the thickness of the photosensitive layer is less than 5 μm, there is a problem that the durability is poor and it cannot be used for a long time. Further, when the thickness of the photosensitive layer exceeds 100 μm, although durability is excellent, there is a problem that sensitivity characteristics deteriorate. Therefore, the value is more preferably 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.

  Further, as shown in FIG. 1B, a barrier layer 16 is formed between the conductive substrate 12 and the photoreceptor layer 14 in the single layer photoreceptor so long as the characteristics of the photoreceptor are not impaired. Single layer type 10 'may be sufficient. Further, as shown in FIG. 1C, a single layer type 10 ″ in which a protective layer 18 is formed on the surface of the photoreceptor 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. 7A, 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. 7B, 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, 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 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 is preferably set to a value in the range of 5 to 500 parts by weight with respect to 100 parts by weight of the binder resin constituting the charge generation layer.

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. 8, the image forming apparatus for wet development includes a charger 32 for performing a charging process and an exposure light source for performing an 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. Even when used for a long time, excellent image characteristics can be maintained.

[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 formula (19) and a hole transport agent are used. ) And 40 parts by weight of a stilbene derivative (HTM-A) represented by formula (12), and 50 parts by weight of a naphthalenecarboxylic acid compound (ETM-A) represented by formula (12) as a binder. As a resin, KF-96 which is a polycarbonate resin represented by the formula (3) and having 100% by weight of a polycarbonate resin (Resin-A) having a viscosity average molecular weight of 50,000 and dimethyl silicone oil as a leveling agent. After containing 0.1 part by weight of -50CS (manufactured by Shin-Etsu Chemical Co., Ltd.) and 750 parts by weight of tetrahydrofuran as a solvent, the mixture is mixed and dispersed with an ultrasonic disperser for 1 hour to obtain a coating solution. It was created.
The obtained coating solution was applied to the entire surface of a conductive base material (anodized aluminum base tube) having a diameter of 30 mm and a length of 254 mm by a dip coating method. 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 having a thickness of 22 μm.
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 Measurement Sensitivity in the obtained multilayer electrophotographic photosensitive member 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).

(2) -2 Evaluation of solvent resistance Isopar L (isoparaffin-based solvent) used as a developing solution for wet development so that the entire surface of the single layer type electrophotographic photoreceptor for wet development is immersed in the photoreceptor layer. , Manufactured by Exxon Chemical Co., Ltd.) was immersed in 500 ml under conditions of a temperature of 25 ° C. and a dark place for 2000 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. As a result, in Examples 1 to 13, the elution amount was 8.0 × 10 ⁻⁷ g · cm ⁻³ or less, and it was found that there was no practical problem.

(2) -3 Appearance Evaluation Further, the appearance of the electrophotographic photoreceptor for wet development after solvent resistance evaluation (after 2000 hours immersion) was visually observed for occurrence of cracks, and the appearance was evaluated according to the following criteria. Carried out.
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) -4 Abrasion Resistance The obtained electrophotographic photoreceptor for wet development is mounted on the image forming apparatus KM-4530 (manufactured by Kyocera Mita Co., Ltd.) modified for wet development so that it becomes 950V. 15,000 copies were made using A4 size paper. Next, the film thickness of the photoreceptor was measured. The value obtained by subtracting the film thickness of the photoconductor after use from the film thickness of the photoconductor before use was defined as the amount of wear (μm). As a result, in Examples 1 to 3, the wear amount was 1.6 μm or less, and it was found that there was no practical problem.

[Examples 2-3]
In Examples 2 to 3, the binder resin in the coating liquid of Example 1 is represented by Formulas (4) and (5) instead of the polycarbonate resin (Resin-A) represented by Formula (3). An electrophotographic photosensitive member for wet development was prepared and evaluated in the same manner as in Example 1 except that 100 parts by weight of each of polycarbonate resins (Resin-B, C) having a viscosity average molecular weight of 50,000 were added. . The obtained results are shown in Table 2.

[Comparative Examples 1-4]
In Comparative Examples 1-4, instead of the polycarbonate resin (Reisn-A) represented by Formula (3) as a binder resin in the coating liquid of Example 1, the following Formulas (23)-(26) An electrophotographic photosensitive member for wet development was prepared and evaluated in the same manner as in Example 1 except that 100 parts by weight of each of the polycarbonate resins (Resin-E to H) having a viscosity average molecular weight of 50,000 were added. . The obtained results are shown in Table 2.

[Comparative Examples 5-6]
In Comparative Examples 5 to 6, instead of the hole transport agent (HTM-A) represented by Formula (8) as the hole transport agent in the coating liquid of Example 1, the following Formulas (27) to ( 28) A wet developing electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 40 parts by weight of each of the hole transport agents (HTM-E to F) having a molecular weight of less than 900 represented by 28) were added. evaluated. The obtained results are shown in Table 2.

[Examples 4 to 6]
In Examples 4 to 6, the charge generating agent in the coating liquid of Example 1 is represented by Formulas (20) to (22) instead of the compound (CGM-A) represented by Formula (19). An electrophotographic photosensitive member for wet development was prepared and evaluated in the same manner as in Example 1 except that 4 parts by weight of each of the charge generating agents (CGM-BD) were added. The obtained results are shown in Table 3.

[Examples 7 to 9]
In Examples 7 to 9, the hole transporting agent in the coating liquid of Example 1 is represented by formulas (9) to (11) instead of the compound (HTM-A) represented by formula (8). An electrophotographic photoreceptor for wet development was prepared and evaluated in the same manner as in Example 1 except that 40 parts by weight of each of the hole transport agents (HTM-BD) to be prepared was added. The obtained results are shown in Table 3.

[Examples 10 to 14]
In Examples 10 to 14, the electron transfer agent in the coating liquid of Example 1 is represented by Formulas (13) to (17) instead of the compound (ETM-A) represented by Formula (12). An electrophotographic photosensitive member for wet development was prepared and evaluated in the same manner as in Example 1 except that 50 parts by weight of each of the electron transporting agents (ETM-BF) were added. The obtained results are shown in Table 3.

As described above in detail, according to the present invention, by using a specific polycarbonate resin and a hole transport agent having a specific molecular weight in combination, even when used for a long time, solvent resistance, abrasion resistance An electrophotographic photosensitive member for wet development having excellent properties and sensitivity characteristics and an image forming apparatus for wet development having the same have been 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.

(A)-(c) is a figure provided in order to demonstrate the basic structure and deformation | transformation structure of a single layer 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 the sensitivity change of a photoreceptor. It is a figure provided in order to demonstrate the relationship between the molecular weight of an electron transfer agent, and the elution amount of an electron transfer agent. It is a figure provided in order to demonstrate the relationship between the elution amount of an electron transport agent, and a repetition characteristic change. It is a figure provided in order to demonstrate the relationship between the I / O value of an electron transport agent, and the elution amount of a hole transport agent. (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: photoreceptor layer 16: barrier layer 18: protective layer 20: laminated photoreceptor 22: charge transport layer 24: charge generation layer 31: photoreceptor 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 (11)

An electrophotographic photoreceptor for wet development comprising a photoreceptor layer comprising a binder resin, a hole transport agent, and a charge generator,
As the binder resin, including a polycarbonate resin represented by the following general formula (1),
An electrophotographic photosensitive member for wet development, comprising a compound having a molecular weight of 900 or more as the hole transport agent.

(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 alkenyl group having 2 to 30 carbon atoms, or carbon (It is a condensed polycyclic hydrocarbon group having a number of 3 to 30.)   2. The electrophotographic photosensitive member for wet development according to claim 1, wherein the addition amount of the hole transport 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. body. 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).

(A in the general formula (2) is a divalent or trivalent organic group, and a plurality of R ^{7 to} R ¹¹ are each independently an hydrogen atom, a halogen atom, a substituted or unsubstituted group having 1 to 20 carbon atoms. An alkyl group, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, or R ^{7 to} R ^{11 is} a hydrocarbon group that may be bonded or condensed to form a ring structure, and the repeating number p is an integer of 2 or 3.)   The electron transport agent is further included, and the addition amount of the electron transport 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. The electrophotographic photosensitive member for wet development according to any one of the above.   The electrophotographic photosensitive member for wet development according to any one of claims 1 to 4, wherein the molecular weight of the electron transfer agent is 600 or more.   6. The electrophotographic image for wet development according to claim 1, wherein an I / O value (inorganic value / organic value) of the electron transfer agent is 0.6 or more. Photoconductor.   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.   The charge generating agent is selected from the group consisting of metal-free phthalocyanine (τ type or x type), titanyl phthalocyanine (α type or Y type), hydroxygallium phthalocyanine (V type), and chlorogallium phthalocyanine (II type). The electrophotographic photoreceptor for wet development according to claim 1, comprising at least one compound. 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 electrophotographic photosensitive member for wet development according to any one of claims 1 to 8.   The electrophotographic photoreceptor for wet development according to any one of claims 1 to 9, wherein the photoreceptor layer is of a single layer type.   The electrophotographic photosensitive member for wet development according to any one of claims 1 to 10 is provided, and a charging step, an exposure step, a developing step, and a transfer step are performed around the electrophotographic photosensitive member for wet development. An image forming apparatus for wet development, in which a portion for the above is disposed and image formation is performed using a liquid developer in which toner is dispersed in a hydrocarbon-based solvent in the development step.

Images