JP2006113312A - 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 having a predetermined sensitivity over a prolonged period of time and excellent in durability and solvent resistance, and to provide an image forming apparatus for wet development. <P>SOLUTION: The electrophotographic photoreceptor for wet development has a photosensitive layer disposed on a conductive support, wherein the photosensitive layer contains, as a hole transport agent, an amine-stilbene derivative represented by formula (1) and having specific substituents in triphenylamine structures at molecular terminals, and a molecular weight of the derivative is set to ≥900. The image forming apparatus for wet development is equipped with such an electrophotographic photoreceptor for wet development. In the formula (1), A-D and R<SP>1</SP>-R<SP>14</SP>are each H, halogen, alkyl, alkyl halide, alkoxy or the like. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member for wet development and an image forming apparatus for wet development. By using a specific hole transport agent, wet development that exhibits excellent solvent resistance and durability and can maintain a predetermined sensitivity. The present invention relates to an electrophotographic photosensitive member and an image forming apparatus for wet development.

Conventionally, as electrophotographic photoreceptors for wet development used in image forming apparatuses, etc., organic photoreceptor materials such as charge transport agents (hole transport agents, electron transport agents), charge generators, and binder resins (binder resins). An organophotoreceptor consisting of Such an organic photoreceptor is advantageous in that it is easy to manufacture and has a wide degree of freedom in structural design because it has various options for the photoreceptor material as compared with conventional inorganic photoreceptors.
Among such organophotoreceptor materials, an electrophotographic photoreceptor using a triphenylamine derivative represented by the following general formula (28) is known as a charge transporting agent having a predetermined charge mobility (for example, , See Patent Document 1).

(In the general formula (28), R ²³ and R ²⁴ are a hydrogen atom, a halogen atom, an alkoxy group, an aryl group, at least two of R ¹⁹ , R ²⁰ , R ²¹ and R ²² are represented by the general formula (29). In the case where the group represented by the general formula (29) is not represented among R ¹⁹ , R ²⁰ , R ²¹ and R ²² , it represents a hydrogen atom.)

(In the general formula (29), R ²⁵ represents a hydrogen atom, a substituted or unsubstituted alkyl group or an aryl group, and R ²⁶ and R ²⁷ each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group. Represents a group or an aryl group, and at least one of R ²⁶ and R ²⁷ represents a substituted or unsubstituted aryl group.)
JP-A-7-36203 (Claims)

  However, the compound described in the specific example of the triphenylamine derivative described in Patent Document 1 has a molecular weight of 900 or less, and has a problem in that it is poorly compatible with the binder resin and tends to cause crystallization. It was. In addition, the electrophotographic photosensitive member containing such a triphenylamine derivative is exclusively considered for use as an electrophotographic photosensitive member for dry development, and there is no mention of use as an electrophotographic photosensitive member for wet development. It was.

Therefore, the present inventors are an amine stilbene derivative having a specific substituent on triphenylamine at the molecular end as a hole transporting agent for an electrophotographic photoreceptor for wet development, and further having a molecular weight of 900 or more. It has been found that the use of the material to be used is excellent in compatibility with the binder resin, so that cracks hardly occur and the amount of elution of the charge transfer agent and the like is remarkably reduced. In addition, the present inventors have found the fact that a predetermined sensitivity characteristic can be maintained because of excellent charge injection properties, and have completed the present invention.
That is, an object of the present invention is to provide an electrophotographic photoreceptor for wet development that is excellent in durability and solvent resistance and can maintain a predetermined sensitivity, and an image forming apparatus provided with such an electrophotographic photoreceptor for wet development. There is.

  According to the present invention, there is provided an electrophotographic photoreceptor for wet development comprising at least a binder resin, a hole transport agent, and a charge generating agent, wherein Provided is an electrophotographic photosensitive member for wet development containing an amine stilbene derivative represented by the formula (1) and having a molecular weight of the amine stilbene derivative of 900 or more, thereby solving the above-mentioned problems. Can do.

(In General Formula (1), A to D and R ^{1 to} R ¹⁴ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or 1 to 20 carbon atoms. A substituted or unsubstituted alkyl halide group, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group, or R Any two of ^{2 to} R ⁶ and any two of R ^{9 to} R ¹³ are carbocyclic structures formed by bonding or condensation, and the repeating numbers a to d are independently 0 to 4 Is an integer.)

  In constructing the electrophotographic photoreceptor for wet development of the present invention, at least two of A, B, C and D in the general formula (1) are substituted or unsubstituted aryl groups having 6 to 15 carbon atoms. It is preferable that

In constituting the electrophotographic photoreceptor for wet development of the present invention, at least two of R ^{2 to} R ⁶ and / or at least two of R ^{9 to} R ^{13 in} the general formula (1) are respectively A substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, or a bonded or condensed carbocyclic structure having 3 to 7 carbon atoms is preferable.

Further, in constituting the electrophotographic photoreceptor for wet development of the present invention, R ² , R ⁶ , R ⁹ and R ^{13 in} the general formula (1) are substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms. Or a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms.

  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.

  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 I / O value (inorganic value / organic value) of the electron transfer agent is preferably 0.6 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, 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, in constituting the electrophotographic photosensitive member for wet development of the present invention, the binder resin includes a polycarbonate resin having an I / O value (inorganic value / organic value) of 0.38 or more. preferable.

Further, when the electrophotographic photosensitive member for wet development according to the present invention is constituted, when it is immersed in a hydrocarbon solvent of a liquid developer at room temperature for 2000 hours, the elution amount of the hole transport agent is 9%. It is preferable that it is below 10 < ^-7 > g / cm < ³ >.

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

  Another aspect of the present invention includes the electrophotographic photosensitive member for wet development described in any of the above, and a charging step, an exposure step, a developing step, and a transfer around the electrophotographic photosensitive member for wet development. This is an image forming apparatus for wet development in which parts for carrying out the steps are arranged and image formation is performed using a liquid developer in the development step.

According to the electrophotographic photosensitive member for wet development of the present invention, as a hole transport agent, an amine stilbene derivative represented by the general formula (1) and a molecular weight that is a predetermined value or more are included. An electrophotographic photoreceptor for wet development having excellent durability and solvent resistance can be provided.
That is, the amine stilbene derivative represented by the general formula (1) introduces a steric hindrance because a vinyl group having a specific substituent is introduced into triphenylamine at the molecular end, and therefore, the phase with the binder resin. Solubility can be improved.
Therefore, by using such an amine stilbene derivative as a hole transport agent in an electrophotographic photoreceptor for wet development, even when used for a long time in a liquid developer, the occurrence of cracks in the photoreceptor layer is suppressed. In addition, it is possible to reduce the elution amount of the charge transfer agent and the like and to maintain predetermined sensitivity characteristics.
Further, according to the electrophotographic photoreceptor for wet development of the present invention, the compatibility with the binder resin is improved by setting the molecular weight of the amine stilbene derivative represented by the general formula (1) to a value equal to or greater than a predetermined value. be able to.
Therefore, by using an amine stilbene derivative having such a molecular weight as a hole transport agent in an electrophotographic photoreceptor for wet development, even when used for a long time in a liquid developer, elution of a charge transport agent and the like Since the amount is small and the compatibility with the binder resin is good, it is possible to provide an electrophotographic photosensitive member for wet development excellent in solvent resistance and durability.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, at least two of A, B, C and D in the general formula (1) are predetermined substituents, so that The compatibility can be further improved.
Therefore, by using an amine stilbene derivative having such a substituent as a hole transporting agent in an electrophotographic photoreceptor for wet development, the amine stilbene derivative is uniformly dispersed in the photoreceptor layer. And the solvent mobility can be improved and the charge mobility can be increased.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, at least two of R ^{2 to} R ⁶ and / or at least two of R ^{9 to} R ^{13 in} the general formula (1) are predetermined. By being a substituent, steric hindrance is caused, so that compatibility with the binder resin can be improved. In addition, since the conjugation extends to the molecular end, charge mobility can be increased.
Therefore, by using an amine stilbene derivative having such a substituent as a hole transport agent in an electrophotographic photosensitive member for wet development, even when it is used in a liquid developer for a long time, Generation of cracks can be suppressed, the amount of elution of the charge transfer agent and the like can be remarkably reduced, and predetermined sensitivity characteristics can be maintained.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, R ² , R ⁶ , R ⁹ and R ^{13 in} the general formula (1) are sterically hindered when they are predetermined substituents. The compatibility with the binder resin can be improved. In addition, since the conjugation extends to the molecular end, charge mobility can be increased.
Therefore, by using an amine stilbene derivative having such a substituent as a hole transport agent in an electrophotographic photosensitive member for wet development, even when it is used in a liquid developer for a long time, Generation of cracks can be suppressed, the amount of elution of the charge transfer agent and the like can be remarkably reduced, and predetermined sensitivity characteristics can be maintained.

  In addition, according to the electrophotographic photoreceptor for wet development of the present invention, the addition amount of the hole transport agent is limited to a value within the range of a predetermined part by weight with respect to 100 parts by weight of the binder resin. It is possible to provide an electrophotographic photoreceptor for wet development that can effectively prevent crystallization of the hole transport agent and is excellent in sensitivity characteristics.

  Further, according to the electrophotographic photosensitive member for wet development of the present invention, an electron transport agent is further included, and the amount of the electron transport agent added is a value within a range of a predetermined part by weight relative to 100 parts by weight of the binder resin. By limiting to the above, it is possible to effectively prevent crystallization of the electron transfer agent and to provide an electrophotographic photoreceptor for wet development which is excellent in sensitivity characteristics.

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 excellent.
Therefore, the use of such an electron transport agent as an electron transport agent in an electrophotographic photoreceptor for wet development not only facilitates the production of the photoreceptor, but also has excellent sensitivity characteristics due to increased charge transport efficiency. Can do. Further, 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 that has excellent solvent resistance against a liquid developer.

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.
Therefore, by including such a charge generator in the electrophotographic photoreceptor for wet development, it is possible to provide an electrophotographic photoreceptor for wet development that is further excellent in sensitivity characteristics, electrical characteristics, stability, and the like.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, by specifying the kind 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 increased. 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.

Further, according to the electrophotographic photoreceptor for wet development of the present invention, the solvent resistance is further improved by limiting the I / O value (inorganic value / organic value) of the binder resin within a predetermined range. Can do.
Therefore, by including such a binder resin in the electrophotographic photoreceptor for wet development, it is possible to provide an electrophotographic photoreceptor for wet development that significantly reduces the elution amount of the charge transport agent and the like even when used for a long time. it can.

  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 by a 2,000 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, when the electrophotographic photoreceptor for wet development is a single layer type, the electrophotographic photoreceptor for wet development having a predetermined sensitivity over a long time can be efficiently produced.

Further, according to the image forming apparatus for wet development of the present invention, when the electrophotographic photoreceptor for wet development is provided with any of the electrophotographic photoreceptors for wet development described above, when immersed in a wet developer for a long time. Even so, 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 charge transfer agent and the like and is excellent in sensitivity characteristics.
Therefore, by providing such an electrophotographic photosensitive member for wet development in an image forming apparatus for wet development, a clear image can be provided for a long time.

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

[First embodiment]
The first embodiment is an electrophotographic photoreceptor for wet development in which a photoreceptor layer is provided on a conductive substrate, and the photoreceptor layer is represented by the following general formula (1) as a hole transport agent. It is an electrophotographic photoreceptor for wet development containing an amine stilbene derivative and containing the amine stilbene derivative having a molecular weight of 900 or more.

(In General Formula (1), A to D and R ^{1 to} R ¹⁴ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or 1 to 20 carbon atoms. A substituted or unsubstituted alkyl halide group, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group, or R Any two of ^{2 to} R ⁶ and any two of R ^{9 to} R ¹³ are carbocyclic structures formed by bonding or condensation, and the repeating numbers a to d are independently 0 to 4 Is an integer.)

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, an amine stilbene derivative (hole transporting agent) represented by the general formula (1), a charge generating agent, a binder resin, and an electron transporting agent, a leveling agent and the like as necessary. Is dissolved or dispersed in a suitable solvent, and the resulting coating solution is applied onto 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.
Further, since the obtained single-layer type photoreceptor contains the amine stilbene derivative represented by the general formula (1), the residual potential is lowered and it has a predetermined sensitivity. .
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) Hole transport agent (2) -1 type The hole transport agent is an amine stilbene derivative represented by the general formula (1) and has a molecular weight of 900 or more. .
This is because the amine stilbene derivative in which a vinyl group having a specific substituent is introduced into the triphenylamine structure at the molecular end is used as a hole transport agent, thereby significantly improving the solvent resistance against hydrocarbon solvents. 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 an amine stilbene derivative in which a specific structure is introduced into the triphenylamine structure at the molecular end, not only can sensitivity characteristics be improved, but also mechanical characteristics and film formability can be improved. It is.
Further, by setting the molecular weight of the amine stilbene derivative to a value of 900 or more, by using the amine stilbene derivative having such a molecular weight as a hole transport agent in an electrophotographic photoreceptor for wet development, This is because the electrophotographic photosensitive member for wet development having excellent solvent resistance and durability can be provided.

Moreover, it is preferable that at least two of A, B, C and D of the amine stilbene are substituted or unsubstituted aryl groups having 6 to 15 carbon atoms.
This is because by having such a substituent, compatibility with the binder resin is improved, and electrical characteristics and heat resistance can be improved. In addition, since the electron distribution is delocalized and planarized, the charge mobility can be increased and the injection property of charges from the charge generating agent can be enhanced.

In addition, at least two of R ^{2 to} R ⁶ and / or R ^{9 to} R ¹³ of the amine stilbene derivative are substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, It is preferably a 10-substituted or unsubstituted alkoxy group, or a bonded or condensed carbocyclic structure having 3 to 7 carbon atoms. Furthermore, at least two of R ^{2 to} R ⁶ and / or at least two of R ^{9 to} R ¹³ are substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, substituted or unsubstituted groups having 1 to 6 carbon atoms. It is more preferable that it is an alkoxy group or a carbocyclic structure having 4 to 5 carbon atoms bonded or condensed.
The reason for this is that by having such a substituent, the planarity of the hole transport agent is lowered due to steric hindrance, and crystallization is more effectively prevented. Further, this is because the compatibility with the binder resin is further excellent, and since it is uniformly dispersed in the photosensitive layer, it is possible to provide an effect of excellent sensitivity characteristics over a long period of time.

In addition, R ² , R ⁶ , R ⁹ and R ^{13 of} such an amine stilbene derivative are a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms or a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms. Is preferred. Furthermore, R ² , R ⁶ , R ⁹ and R ¹³ are more preferably a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms and a substituted or unsubstituted alkoxy group having 1 to 3 carbon atoms.
The reason for this is that by having such a substituent, the planarity of the hole transport agent is reduced due to steric hindrance, and more effectively prevents crystallization, and the compatibility with the binder resin is further excellent. This is because since it is uniformly dispersed in the photosensitive layer, it is possible to provide an effect of excellent sensitivity characteristics over a long period of time. In addition, such a structure is easy to manufacture, so that an electrophotographic photoreceptor for wet development can be provided at a relatively low cost.

(2) -2 Specific Example In addition, as specific examples of the amine stilbene derivative represented by the general formula (1), amine stilbene derivatives (HTM-A to D) represented by the following structural formulas (2) to (5) Indicates.

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

(2) -3 Addition amount Further, regarding the addition amount of the hole transport agent, it is preferable to set the 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 to set the addition amount of the hole transport agent to a value within the range of 30 to 70 parts by weight.

(3) Electron transfer agent (3) -1 I / O value (inorganic value / organic value)
In selecting an electron transfer agent, the I / O value is preferably 0.6 or more.
The reason for this is that by limiting the I / O value of the electron transport agent to a specific range, the inorganicity of the electron transport agent is increased, and the solvent resistance is excellent with respect to hydrocarbon solvents that are organic solvents. Is obtained. However, when the value of the I / O value becomes excessively large, the solubility in the solvent and the binder resin may be lowered.
Therefore, the I / O value of the electron transport agent is more preferably set to a value within the range of 0.7 to 1.7, and further preferably set to a value within the range of 0.8 to 1.5.
Specifically, it is preferable that the inorganic value (I value) of the electron transfer agent is a value in the range of 240 to 900, and the organic value (O value) is a value in the range of 240 to 1000.

  Here, the inorganic value (I value) and the organic value (O value) used in the present invention, and the I / O value, which 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-D) represented by the formula (9) described later is calculated as follows.
That is, the compound has 23 carbon atoms (organic 20) and 1 nitro group (organic 70), and the organic value is 20 × 23 + 70 = 530. It also has one naphthalene ring (inorganic 60), two benzene rings (inorganic 15), two ketone groups (inorganic 65), and one nitro group (inorganic 70). Since it has one and one carboxyl group (inorganic 60), the inorganic value is 60 × 1 + 15 × 2 + 65 × 2 + 70 + 60 = 350. Therefore, the I / O value of such a compound is 350/530 = 0.6604.

In addition, the specific electron transport 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). 6-30 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.

  In addition, when it is desired to obtain further excellent solvent resistance, the above-described electron transporting agent excludes two or more substituted carboxyl groups or two or more substituted carbonyl groups (however, the quinone moiety ketone group is excluded). ) Is more preferable.

(3) -2 Types In addition, the type of the electron transport agent preferably includes 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.

(3) -3 Specific Examples Specific examples of these electron transfer agents include compounds (ETM-A to F) represented by the following formulas (6) to (11).

It is also preferable to use a conventionally known electron transport agent in combination. Examples of such electron transporting agents include diphenoquinone derivatives, benzoquinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, Dinitroacridine derivatives, nitroantharaquinone derivatives, dinitroanthraquinone derivatives, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride And various compounds having an electron accepting property such as dibromomaleic anhydride, and it is preferable to use one compound alone or a mixture of two or more compounds.
Of these compounds, the concentration is adjusted to 40% by weight with respect to 60% by weight of the resin, and the electron mobility at an electric field strength of 5 × 10 ⁵ v / cm is 1.0 × 10 ^−8. An electron transfer agent having a cm ² / V / sec or more is more preferable.

(3) -4 Addition amount In constituting the electrophotographic photoreceptor for wet development, the addition amount of the electron transport agent is 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, the addition amount of the electron transport agent is more preferably set to a value in 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 a hole transport agent mentioned above. More specifically, the addition ratio (total ETM / total HTM) of the electron transport agent (total ETM) is a value within the range of 0.25 to 1.3 with respect to the hole transport agent (total HTM). It is preferable to do.
This is because if the ratio of all ETMs / all HTMs is outside this range, the sensitivity is lowered, which may cause practical problems.
Therefore, it is more preferable that the ratio of the total ETM / total HTM is set to a value within the range of 0.5 to 1.25.

(4) Charge generator (4) -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 having more excellent 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.

(4) -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 (12) to (15). 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- One kind of inorganic photoconductive agent material such as arsenic, cadmium sulfide, and amorphous silicon, or a mixture of two or more kinds may be used.

(4) -3 Addition 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 or 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 that the amount of the charge generating agent is set to a value within the range of 0.5 to 20 parts by weight with respect to 100 parts by weight of the binder resin.

Moreover, when using the compound (CGM-B) represented by Formula (13) among the charge generating agents used in the present invention, a dispersion aid represented by the following Formulas (16) and (17) ( Pigment Orange 16 and Pigment Yellow 93) may be added.
The reason for this is to improve the dispersibility of CGM-B in the coating solution and lengthen the pot life of the coating solution by using the charge generating agent (CGM-B) and the dispersion aid together. It is because it can do.

In addition, when using the dispersion | distribution adjuvant represented by Formula (16) and (17), let the addition amount be the value within the range of 30-200 weight part with respect to 100 weight part of all the electric charge generating agents. It is preferable.
This is because when the amount of the dispersion aid added is less than 30 parts by weight, the solubility in the solvent and the binder resin becomes insufficient, and an appropriate film as a photoreceptor cannot be produced. On the other hand, when the dispersion aid exceeds 200 parts by weight, the effect of increasing the quantum yield of the charge generating agent becomes insufficient, and the sensitivity characteristics, electrical characteristics, stability, etc. of the electrophotographic photoreceptor can be improved. It is because it becomes impossible.

(5) Binder Resin (5) -1 Type As the binder resin for dispersing the charge generator and the like, a polycarbonate having an I / O value (inorganic value / organic value) of 0.38 or more. It is preferable to use a resin.
This is because the polycarbonate resin having such a structure can further improve the solvent resistance of the organic photoreceptor.

In constituting the amine stilbene derivative of the present invention, a polycarbonate resin represented by the following general formula (18) is preferable.
This is because such a polycarbonate resin is hardly soluble in a hydrocarbon solvent without introducing a siloxane structure or the like and has high oil repellency. As a result, the interaction between the surface of the photoreceptor layer and the above-described hydrocarbon solvent becomes small, and the change in the appearance of the surface of the photoreceptor layer is reduced over a long period of time.

(In the general formula (18), R ¹⁵ , R ¹⁶ , R ¹⁷ , and R ¹⁸ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, A substituted or unsubstituted halogenated 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 6 to 30 carbon atoms, or a carbon number of 10 to 30 And X is a single bond, —O—, or —CO—.)

(5) -2 Specific example Moreover, as a specific example of polycarbonate resin represented by General formula (18), the compound (Resin-A-Resin-D) shown, for example by following formula (19)-(22) is shown, for example. Is mentioned.

However, it is also preferable to use various resins conventionally used in 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, Polyamide resin, polyurethane resin, polysulfone resin, diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin and other thermoplastic resins, 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.
Of these binder resins, it is more preferable to use a polycarbonate resin.
This is because a polycarbonate resin is generally insoluble in hydrocarbon solvents and has high oil repellency. As a result, the interaction between the surface of the photoreceptor layer and the above-described hydrocarbon solvent becomes small, and the change in the appearance of the surface of the photoreceptor layer is reduced over a long period of time.

(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 and other metals, plastic materials on which these metals are deposited or laminated, plastic materials in which conductive fine particles such as carbon black are dispersed, 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, regarding the configuration of the single-layer type photoreceptor, as shown in FIG. 1B, a barrier layer 16 is formed between the conductive substrate 12 and the photoreceptor layer 14 within a range that does not impair the characteristics of the photoreceptor. The single-layer type photoreceptor 10 ′ may be used. Further, as shown in FIG. 1C, a single layer type photoreceptor 10 ″ in which a protective layer 18 may be 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 And muamide, 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. 2A, the laminated photoreceptor 20 generates a charge containing a charge generating agent on a conductive substrate 12 by means of vapor deposition or coating. A layer 24 is formed, and then a coating liquid containing at least one amine stilbene derivative or the like as a hole transport agent and a binder resin is applied onto the charge generation layer 24 and dried to form the charge transport layer 22. It is produced by forming.
Contrary to the above structure, as shown in FIG. 2B, a multilayer photoreceptor 20 in which a charge transport layer 22 is formed on a conductive substrate 12 and a charge generation layer 24 is formed thereon. ´ is also good.
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 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, the charge transport agent in the charge transport layer is an amine stilbene derivative represented by the general formula (1) When a hole transport agent is used, the photoreceptor becomes a negatively charged 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 (hereinafter sometimes simply referred to as a photosensitive member) according to the first embodiment, and is provided around the electrophotographic photosensitive member for wet development. A charging device 32 for carrying out the charging process, an exposure light source 33 for carrying out the exposure process, a wet developing device 34 for carrying out the developing process, and a transfer machine 35 for carrying out the transferring process, In addition, the image forming apparatus for wet development performs image formation using a liquid developer in which a toner is dispersed in a hydrocarbon solvent in a development step.
In the following description of the image forming apparatus for wet development, it is assumed that a single-layer type photoreceptor is used as the electrophotographic photoreceptor.

That is, as shown in FIG. 3, the image forming apparatus for wet development includes a charger 32 for performing a charging process, an exposure light source 33 for performing an exposure process, and a developing process around a photosensitive member 31. It is preferable to include at least a wet developing unit 34 for performing the transfer process and a transfer unit 35 for performing the transfer process.
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.
In the photoreceptor 31, by using a specific amine stilbene derivative as a hole transport agent, a single layer type electrophotographic photoreceptor for wet development having excellent solvent resistance and sensitivity characteristics can be obtained. In addition, excellent image characteristics can be maintained.

[Example 1]
(1) Preparation of electrophotographic photosensitive member for wet development As a charge generating agent, 4 parts by weight of X-type metal-free phthalocyanine (CGM-A) represented by formula (12) and a hole transporting agent are used. 40 parts by weight of the amine stilbene derivative (HTM-A) represented by formula (6), 50 parts by weight of the naphthoquinone derivative (ETM-A) represented by formula (6) as the electron transporting agent, and a binder resin 100 parts by weight of a polycarbonate resin (Resin-A) having a viscosity average molecular weight of 50,000 represented by the formula (19) and KF-96-50CS (manufactured by Shin-Etsu Chemical Co., Ltd.) which is a dimethyl silicone oil as a leveling agent Of 0.1 part by weight and 750 parts by weight of tetrahydrofuran as a solvent were mixed and dispersed by an ultrasonic disperser for 1 hour to prepare a coating solution.
The obtained coating solution was applied to the entire outer surface of the anodized aluminum base tube having a diameter of 30 mm, a length of 254 mm, and a thickness of 5 μm. Thereafter, it was dried with hot air at 130 ° C. for 30 minutes to obtain an electrophotographic photoreceptor for wet development having a single-layer photoreceptor layer with a thickness of 22 μm.
The viscosity average molecular weight (M) of the copolymer polycarbonate is determined by measuring the intrinsic viscosity [η] with an Ostwald viscometer, and using the formula [η] = 1.23 × 10 ⁻⁴ M ^0.83. Was calculated.

(2) Evaluation (2) -1 Sensitivity Measurement The light potential in the obtained electrophotographic photoreceptor for wet development was measured. That is, using a drum sensitivity tester (produced by GENTEC), it was charged to 850 V, and then monochromatic light with a wavelength of 780 nm (half-value width: 20 nm, light amount) extracted from the light of the halogen lamp using a hand pulse filter. : 1.0 μJ / cm ² ). The potential after the elapse of 330 msec after the exposure was measured and used as the initial sensitivity (V).
The whole electrophotographic photosensitive member for wet development was immersed in 500 ml of a hydrocarbon solvent (manufactured by Exxon Chemical Co .: Nopa 12) used as a developer for wet development at a temperature of 25 ° C. for 2000 hours. did. Thereafter, the electrophotographic photosensitive member for wet development was taken out from the hydrocarbon solvent, the sensitivity was measured in the same manner, and the difference from the initial sensitivity was defined as the sensitivity change (Vr−Vo) as post-immersion sensitivity (Vr). The obtained results are shown in Table 2.

(2) -2 Evaluation of solvent resistance 500 ml of a hydrocarbon solvent (nopa 12) which is a hydrocarbon solvent so that the obtained electrophotographic photoreceptor for wet development is immersed in the entire surface of the photoreceptor layer. Were immersed under conditions of a temperature of 25 ° C. and 2000 hours. On the other hand, the concentration of the hole transport agent was changed and dissolved in a hydrocarbon solvent (nopa 12). In this state, the absorbance at the absorption peak wavelength from the ultraviolet region to the visible region was measured, and a concentration-absorbance calibration curve for the hole transport agent was prepared in advance. Next, the electrophotographic photosensitive member for wet development immersed in a hydrocarbon solvent (nopa 12) is subjected to absorption measurement from the ultraviolet region to the visible region, and in the light of the calibration curve, from the ultraviolet region to the visible region of the hole transport agent. The elution amount of the hole transport agent was calculated from the absorbance at the absorption peak wavelength. The obtained results are shown in Table 2.

(2) -3 Appearance Evaluation Further, the appearance of the electrophotographic photoreceptor for wet development after the solvent resistance evaluation was visually observed for occurrence of cracks, and the appearance was evaluated according to the following criteria. The obtained results are shown in Table 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.

[Example 2]
In Example 2, instead of the metal-free phthalocyanine (CGM-A) represented by Formula (12) as the charge generator used in Example 1, the compound (CGM-) represented by Formula (13) described above was used. A single layer type photoconductor was prepared and evaluated in the same manner as in Example 1 except that 4 parts by weight of B) and 3 parts by weight of the dispersion auxiliary agent (Pigment Yellow 16) represented by formula (17) were added.

[Examples 3 to 4]
In Examples 3-4, instead of the metal-free phthalocyanine (CGM-A) represented by Formula (12) as the charge generator used in Example 1, it is represented by Formulas (14)-(15) described above. A single-layer photoreceptor was prepared and evaluated in the same manner as in Example 1 except that each of the compounds (CGM-C, D) obtained was used.

[Examples 5 to 7]
In Examples 5 to 7, instead of the amine stilbene derivative (HTM-A) represented by the formula (2) as the hole transport agent used in Example 1, the formulas (3) to (5) described above are used. A single layer type photoreceptor was prepared and evaluated in the same manner as in Example 1 except that each of the amine stilbene compounds (HTM-BD) represented was used.

[Examples 8 to 10]
In Examples 8-10, instead of the polycarbonate resin (Resin-A) represented by Formula (19) as the binder resin used in Example 1, it is represented by Formulas (20)-(22) described above. A single-layer photoreceptor was prepared and evaluated in the same manner as in Example 1 except that polycarbonate resins (Resin-BD) having a viscosity average molecular weight of 50,000 were used.

[Examples 11 to 15]
In Examples 11-15, instead of the naphthoquinone derivative (ETM-A) represented by Formula (6) as the electron transport agent used in Example 1, it is represented by Formulas (7) to (11) described above. A single-layer type photoconductor was prepared and evaluated in the same manner as in Example 1 except that each electron transport agent (ETM-BF) was used.

[Comparative Examples 1-4]
In Comparative Examples 1 to 4, as the hole transport agent used in Example 1, instead of the amine stilbene derivative (HTM-A) represented by the formula (2), the following formulas (23) to (26) An electrophotographic photoreceptor for wet development was prepared and evaluated in the same manner as in Example 1 except that the represented compounds (HTM-E to H) were used.

[Comparative Example 5]
In Comparative Example 5, instead of the polycarbonate resin (Resin-A) represented by Formula (19) as the binder resin used in Comparative Example 4, the viscosity average molecular weight represented by the following Formula (27) is 50, A single-layer photoreceptor was prepared and evaluated in the same manner as in Comparative Example 4 except that 000 polycarbonate resin (Resin-E) was used.

As described above in detail, in the amine stilbene derivative used as a hole transport agent, the triphenylamine at the molecular end has a vinyl group having a specific structure, and the molecular weight is set to a value of 900 or more, so that it is wet. The electrophotographic photosensitive member for development has excellent compatibility with the binder resin, can maintain a predetermined sensitivity for a long time, and can obtain excellent durability and solvent resistance.
Therefore, the electrophotographic photoreceptor for wet development according to the present invention is expected to contribute to speeding up and performance enhancement of various image forming apparatuses.

(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. It is a figure provided in order to demonstrate the image forming apparatus provided with the electrophotographic photoreceptor 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 (13)

An electrophotographic photoreceptor for wet development comprising a photoreceptor layer containing at least a binder resin, a hole transport agent, and a charge generator,
An electrophotographic photosensitive member for wet development, comprising an amine stilbene derivative represented by the following general formula (1) as the hole transporting agent and having a molecular weight of 900 or more.

(In General Formula (1), A to D and R ^{1 to} R ¹⁴ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or 1 to 20 carbon atoms. A substituted or unsubstituted alkyl halide group, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group, or R Any two of ^{2 to} R ⁶ and any two of R ^{9 to} R ¹³ are carbocyclic structures formed by bonding or condensation, and the repeating numbers a to d are independently 0 to 4 Is an integer.)   2. The wet development according to claim 1, wherein at least two of A, B, C and D in the general formula (1) are substituted or unsubstituted aryl groups having 6 to 15 carbon atoms. Electrophotographic photoreceptor. In the general formula (1), at least two of R ^{2 to} R ⁶ and / or at least two of R ^{9 to} R ¹³ are each a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, carbon number The electrophotographic photosensitive member for wet development according to claim 1 or 2, which is a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, or a bonded or condensed carbocyclic structure having 3 to 7 carbon atoms. R ² , R ⁶ , R ⁹ and R ^{13 in the} general formula (1) are substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms, or substituted or unsubstituted alkoxy groups having 1 to 6 carbon atoms. The electrophotographic photosensitive member for wet development according to any one of claims 1 to 3, wherein the electrophotographic photosensitive member is for wet development.   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 photoreceptor layer further includes an electron transport agent, and the amount of the electron transport agent added 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 photoreceptor for wet development according to any one of claims 1 to 5.   7. The electrophotographic photosensitive member for wet development according to claim 6, wherein the I / O value (inorganic value / organic value) of the electron transfer agent is 0.6 or more.   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 generator 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 photosensitive member for wet development according to claim 1, comprising at least one compound.   The polycarbonate resin having an I / O value (inorganic value / organic value) of 0.38 or more is included as the binder resin. An electrophotographic photoreceptor for wet development. The elution amount of the hole transport agent is 9 × 10 ⁻⁷ g / cm ³ or less when immersed in a hydrocarbon solvent of a liquid developer at room temperature for 2000 hours. The electrophotographic photosensitive member for wet development according to any one of claims 1 to 10.   The electrophotographic photosensitive member for wet development according to any one of claims 1 to 11, wherein the photosensitive layer is a single layer type.   The electrophotographic photosensitive member for wet development according to any one of claims 1 to 12 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.

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