JP2015176062A - Electrophotographic photoreceptor, process cartridge, and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor for achieving the alleviation of sustained contact stress against a contact member, etc. and the potential stability of the electrophotographic photoreceptor during its repeated use and also having those properties stably, and a process cartridge and an electrophotographic device having the electrophotographic photoreceptor.SOLUTION: An electric charge transport layer in the electrophotographic photoreceptor has an electric charge transport substance and a specific structural unit, and also includes a polyester resin in which the amount of volatile siloxane is 150 ppm or less.

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

  As an electrophotographic photosensitive member mounted on a process cartridge or an electrophotographic apparatus, an electrophotographic photosensitive member containing an organic photoconductive substance is mainly used. The electrophotographic photoreceptor generally has a support and a photosensitive layer containing an organic photoconductive substance on the support. The photosensitive layer is generally a laminated type (normal layer type) in which a charge generation layer and a charge transport layer are laminated in this order from the support side.

  In the electrophotographic process, various materials (hereinafter also referred to as “contact members”) such as a developer, a charging member, a cleaning blade, paper, and a transfer member come into contact with the surface of the electrophotographic photosensitive member. Therefore, characteristics required for the electrophotographic photosensitive member include reduction of image deterioration due to contact stress with these contact members and the like. In particular, as the durability of electrophotographic photoreceptors has improved in recent years, further improvements have been made regarding the sustainability of the effect of reducing image deterioration due to the contact stress and the potential stability during repeated use (suppression of potential fluctuations). It is desired.

  Regarding continuous relaxation of contact stress and potential stability during repeated use of an electrophotographic photoreceptor, Patent Document 1 discloses an electrophotography in which a siloxane-modified resin having a siloxane structure incorporated in a molecular chain is brought into contact with the above-mentioned various members. It has been proposed to be included in the surface layer of the photoreceptor.

International Publication No. WO2010 / 008095

  The electrophotographic photosensitive member disclosed in Patent Document 1 can achieve both the continuous relaxation of contact stress and the potential stability during repeated use by using a polyester resin having a specific siloxane structure.

  Here, as a result of studies by the present inventors, it has been found that there is room for improvement as to means for stably obtaining an electrophotographic photosensitive member excellent in potential stability during repeated use.

  An object of the present invention is to provide an electrophotographic photosensitive member capable of achieving both a high level of potential stability at the time of repeated relaxation of contact stress and repeated use of the electrophotographic photosensitive member, and capable of stably obtaining the characteristics. It is to provide. Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  The present invention relates to an electrophotographic photoreceptor having a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer, wherein the charge transport layer is a surface layer. And the charge transport layer has a charge transport material, a structural unit represented by the following formula (A) and a structural unit represented by the following formula (B), and the amount of volatile siloxane is 150 ppm or less An electrophotographic photoreceptor containing resin A.

式（Ａ）中、Ｘ^１は、ｍ−フェニレン基、ｐ−フェニレン基、または２つのｐ−フェニレン基が酸素原子を介して結合した２価の基を示す。Ｒ^１１およびＲ^１２は、それぞれ独立に、メチル基、エチル基、またはフェニル基を示す。ｎは、括弧内の繰り返し数を示し、ポリエステル樹脂Ａにおけるｎの平均値は、２０以上１２０以下である。

In formula (A), X ¹ represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded through an oxygen atom. R ¹¹ and R ¹² each independently represent a methyl group, an ethyl group, or a phenyl group. n represents the number of repetitions in parentheses, and the average value of n in the polyester resin A is 20 or more and 120 or less.

式（Ｂ）中、Ｘ^２は、ｍ−フェニレン基、ｐ−フェニレン基、または２つのｐ−フェニレン基が酸素原子を介して結合した２価の基を示す。

In formula (B), X ² represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded through an oxygen atom.

  Further, the present invention integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, and a cleaning means, and is detachable from the main body of the electrophotographic apparatus. A process cartridge.

  The present invention also provides an electrophotographic apparatus having the electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit.

  According to the present invention, there is provided an electrophotographic photosensitive member capable of achieving both a continuous relaxation of contact stress and a potential stability upon repeated use of the electrophotographic photosensitive member at a high level, and stably obtaining the characteristics. Can be provided. Further, according to the present invention, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member can be provided.

1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention.

  The present invention relates to an electrophotographic photoreceptor having a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer, wherein the charge transport layer is a surface layer. In the above, the charge transport layer contains a charge transport material and a polyester resin A. The polyester resin A has a structural unit represented by the following formula (A) and a structural unit represented by the following formula (B), and the amount of volatile siloxane is 150 ppm or less.

式（Ａ）中、Ｘ^１は、ｍ−フェニレン基、ｐ−フェニレン基、または２つのｐ−フェニレン基が酸素原子を介して結合した２価の基を示す。Ｒ^１１およびＲ^１２は、それぞれ独立に、メチル基、エチル基、またはフェニル基を示す。ｎは、括弧内の繰り返し数の平均値を示し、ポリエステル樹脂Ａにおけるｎの平均値は２０以上１２０以下である。

In formula (A), X ¹ represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded through an oxygen atom. R ¹¹ and R ¹² each independently represent a methyl group, an ethyl group, or a phenyl group. n shows the average value of the number of repetitions in parentheses, and the average value of n in the polyester resin A is 20 or more and 120 or less.

式（Ｂ）中、Ｘ^２は、ｍ−フェニレン基、ｐ−フェニレン基、または２つのｐ−フェニレン基が酸素原子を介して結合した２価の基を示す。

In formula (B), X ² represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded through an oxygen atom.

The polyester resin A constituting the charge transport layer according to the present invention will be described.
The polyester resin A has a structural unit represented by the above formula (A) and a structural unit represented by the above formula (B).

X ¹ in the formula (A) represents a divalent group in which an m-phenylene group, a p-phenylene group, or two p-phenylene groups are bonded through an oxygen atom. These groups may be used independently and may use 2 or more types together. When m-phenylene group and p-phenylene group are used in combination, the ratio (molar ratio) of m-phenylene group to p-phenylene group is preferably 1: 9 to 9: 1. 3: 7 to 7: 3 is more preferable.

In formula (A), R ¹¹ and R ¹² are preferably methyl groups from the viewpoint of continuous relaxation of the contact stress.

  The average value of n in the polyester resin A in the formula (A) is 20 or more and 120 or less. In particular, the average value of n is preferably 40 or more and 80 or less. Further, the number of repetitions n of the structure in parentheses is preferably within a range of ± 10% of the value represented by the average value of the number of repetitions of n, from the viewpoint of stably obtaining the effects of the present invention.

Specific examples of the structural unit represented by the formula (A) are shown below.

Among these, the structural unit represented by the above formula (A-2), (A-3), (A-6), (A-7), (A-10) or (A-11) is preferable. Further, the above structural units may be used alone or in combination. When a structural unit in which X ¹ is an m-phenylene group and a p-phenylene group is used in combination, the ratio (molar ratio) of the m-phenylene group to the p-phenylene group is preferably 1: 9 to 9: 1. It is more preferable that it is 3: 7-7: 3.

Examples of the structural unit represented by the formula (B) are shown below.

  The content of the structural unit represented by the formula (A) with respect to the total mass of the polyester resin A is preferably 6% by mass or more and 40% by mass or less. When the content of the structural unit represented by the formula (A) with respect to the total mass of the polyester resin A is 6% by mass or more, the contact stress mitigating effect is continuously exhibited. Further, when the content of the structural unit represented by the formula (A) is 40% by mass or less, the mechanical strength can be maintained.

  Moreover, it is preferable that content of the structural unit shown by Formula (B) with respect to the total mass of the polyester resin A is 60 mass% or more. When the content of the structural unit represented by the formula (B) with respect to the total mass of the polyester resin A is 60% by mass or more, the contact stress mitigating effect is continuously exhibited.

  Moreover, as a structural unit which comprises the polyester resin A, structural units other than the structural unit shown by Formula (A) and the structural unit shown by Formula (B) can be used. Specific examples include structural units represented by the following formulas (C-1) to (C-12). When a structural unit other than the structural unit represented by the formula (A) and the structural unit represented by the formula (B) is used, the structure represented by the formula (A) with respect to the total mass of the polyester resin A from the viewpoint of the effect of the present invention. The content of the structural unit other than the unit and the structural unit represented by the formula (B) is preferably 34% by mass or less. Furthermore, it is preferable that it is 30 mass% or less.

  The polyester resin A is a copolymer of a structural unit represented by the formula (A) and a structural unit represented by the formula (B). The copolymerization form may be any form such as block copolymerization, random copolymerization, and alternating copolymerization.

  The content of the structural unit represented by the above formula (A) and the content of the structural unit represented by the above formula (B) with respect to the total mass of the polyester resin A can be analyzed by a general analysis method. Examples of analysis methods are shown below.

  First, the charge transport layer which is the surface layer of the electrophotographic photosensitive member is dissolved with a solvent. Thereafter, various materials contained in the charge transport layer, which is the surface layer, are fractionated by a fractionation apparatus capable of separating and recovering each composition component such as size exclusion chromatography and high performance liquid chromatography. The separated polyester resin A is hydrolyzed in the presence of alkali or the like to decompose into a carboxylic acid moiety and a bisphenol moiety. The obtained bisphenol moiety is subjected to nuclear magnetic resonance spectrum analysis and mass spectrometry, and the number of repeating units and the molar ratio of the structural unit represented by formula (A) and the structural unit represented by formula (B) are calculated. Convert to (mass ratio).

  The weight average molecular weight of the polyester resin A is preferably 30,000 or more and 200,000 or less. Furthermore, it is more preferable that it is 40,000 or more and 150,000 or less.

  In the present application, the weight average molecular weight of the resin is a polystyrene-reduced weight average molecular weight measured by a method described in JP 2007-79555 A, in accordance with a conventional method.

In the present application, the volatile siloxane amount refers to a value obtained by measurement as follows according to a conventional method.
That is, 10 mg of a resin sample (polyester resin A) was heated at 165 ° C. for 10 minutes using a commercially available pyrolyzer and analyzed with a gas chromatograph mass spectrometer. The amount of volatile matter is calculated using a calibration curve prepared using hexadecane as a standard sample.

  In addition to the polyester resin A, a polyester resin C represented by the following formula (C) or a polycarbonate resin D represented by the following formula (D) is mixed in the binder resin used for the charge transport layer of the electrophotographic photosensitive member of the present invention. May be.

式（Ｃ）中、Ｒ^３１〜Ｒ^３８は、それぞれ独立に、水素原子、またはメチル基を示す。Ｘ^３は、ｍ−フェニレン基、ｐ−フェニレン基、または２つのｐ−フェニレン基が酸素原子を介して結合した２価の基を示す。Ｙ^３は、単結合、メチレン基、エチリデン基、またはプロピリデン基を示す。

In formula (C), R ^{31 to} R ³⁸ each independently represent a hydrogen atom or a methyl group. X ³ represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom. Y ³ represents a single bond, a methylene group, an ethylidene group, or a propylidene group.

式（Ｄ）中、Ｒ^４１〜Ｒ^４８は、それぞれ独立に、水素原子、またはメチル基を示す。Ｙ^４は、メチレン基、エチリデン基、プロピリデン基、フェニルエチリデン基、シクロヘキシリデン基、または酸素原子を示す。

In formula (D), R ^{41 to} R ⁴⁸ each independently represent a hydrogen atom or a methyl group. Y ⁴ represents a methylene group, an ethylidene group, a propylidene group, a phenylethylidene group, a cyclohexylidene group, or an oxygen atom.

Next, the polyester resin C having the structural unit represented by the formula (C) will be described.
X ³ in the formula (C) represents a divalent group in which an m-phenylene group, a p-phenylene group, or two p-phenylene groups are bonded via an oxygen atom. These groups may be used independently and may use 2 or more types together. When m-phenylene group and p-phenylene group are used in combination, the ratio (molar ratio) of m-phenylene group to p-phenylene group is preferably 1: 9 to 9: 1. 3: 7 to 7: 3 is more preferable.
Y ³ in formula (C) is preferably a propylidene group.

Specific examples of the structural unit represented by the formula (C) are shown below.

  Among these, the structural unit represented by the above formula (C-1), (C-2), (C-4), (C-5) or (C-9) is preferable.

Next, the polycarbonate resin D having the structural unit represented by the formula (D) will be described.
Y ⁴ in the formula (D) is preferably a propylidene group or a cyclohexylidene group.

Specific examples of the structural unit represented by the formula (D) are shown below.

  Among these, a structural unit represented by the formula (D-1), (D-2), (D-3) or (D-4) is preferable.

で示されるジカルボン酸ハライド４８．４ｇをジクロロメタンに溶解させ、酸ハロゲン化物溶液を調製した。
また、酸ハロゲン化物溶液とは別に、下記式（２−１）

で示されるシロキサン構造を有するジオール９．４ｇおよび下記式（３−１）

で示されるジオール５４．２ｇを１０％水酸化ナトリウム水溶液に溶解させた。さらに、重合触媒としてトリブチルベンジルアンモニウムクロライドを添加して攪拌し、ジオール化合物溶液を調製した。
次に、上記酸ハロゲン化物溶液を上記ジオール化合物溶液に攪拌しながら加え、重合を開始した。重合は、反応温度を２５℃以下に保ち、攪拌しながら、３時間行った。
その後、酢酸の添加により重合反応を終了させ、水相が中性になるまで水での洗浄を繰り返した。洗浄後、攪拌下のメタノールに滴下して、重合物を沈殿させ、この重合物を真空乾燥させた後、１６５℃で１６時間乾燥させることで上記式（Ａ−１０）および（Ｂ−３）で示される構造単位を有するポリエステル樹脂Ａ（Ａ１）を得た。 Below, the synthesis example of the polyester resin A is shown.
[Synthesis Example 1]
Synthesis of polyester resin A (A1) having structural units represented by the above formulas (A-10) and (B-3) The following formula (1-1)

48.4 g of the dicarboxylic acid halide represented by the above formula was dissolved in dichloromethane to prepare an acid halide solution.
In addition to the acid halide solution, the following formula (2-1)

Diol having a siloxane structure represented by the following formula (3-1)

Was dissolved in a 10% aqueous sodium hydroxide solution. Further, tributylbenzylammonium chloride was added as a polymerization catalyst and stirred to prepare a diol compound solution.
Next, the acid halide solution was added to the diol compound solution with stirring to initiate polymerization. The polymerization was carried out for 3 hours while maintaining the reaction temperature at 25 ° C. or lower and stirring.
Thereafter, the polymerization reaction was terminated by the addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral. After washing, the solution is added dropwise to methanol with stirring to precipitate a polymer. The polymer is vacuum-dried and then dried at 165 ° C. for 16 hours, whereby the above formulas (A-10) and (B-3) are obtained. Polyester resin A (A1) having a structural unit represented by

It was 10 mass% when content of the structural unit shown by the said Formula (A-10) with respect to the total mass of the polyester resin A (A1) was computed by the above-mentioned method. Moreover, the weight average molecular weight of the polyester resin A (A1) was 90,000.
Moreover, when the amount of volatile siloxane of the polyester resin A was computed by the above-mentioned method, it was 108 ppm.

  Furthermore, the acid value, catalyst content, diphenyl ether dicarboxylic acid (DEDA) content, and alkali metal content of the polyester resin A (A1) were measured using the method described below.

The acid value was measured by a back titration method.
The catalyst content (residual catalyst amount) was quantified by gas chromatography under the following conditions. A 0.5 g sample of polyester resin A was dissolved in 10 ml of chloroform and reprecipitated with methanol. As a standard, 50 μg of diphenyl was added to this reprecipitation solution, and the total amount was adjusted to 50 ml with methanol. This sample was measured with a gas chromatograph [column: methyl silicon capillary (5 m × 0.53 mm), column temperature: 250 ° C., carrier gas: He, detector: FID], and the catalyst content was determined from the peak area.

  The DEDA content was measured using the following method. A 0.2 g sample of polyester resin A was dissolved in 3 ml of acetonitrile and allowed to stand for 72 hours. Next, the acetonitrile solution was separated from insolubles using a filter having a pore diameter of 0.45 μm to obtain a sample solution. This sample solution was measured with a gas chromatograph apparatus (HP6890 Series GC System, manufactured by Hewlett-Packard Company) [column: methyl silicon capillary (5 m × 0.53 mm), column temperature: 250 ° C., carrier gas: He, detector: FID]. The DEDA content was determined from the peak area of diphenyl ether dicarboxylic acid.

The alkali metal content was measured using the following method. A 1 g sample of polyester resin A was made into a solution using a microwave wet decomposition apparatus (MLS-1200MEGA, MDR1000 / 160/60 rotor manufactured by Milestone) under the following conditions, and an ICP emission analyzer (ICAP-575 manufactured by Nippon Jarrell-Ash). The alkali metal content was measured in -II).
(Solution conditions)
・ 1st step: H ₂ SO ₄ 3 ml
・ 2nd step: HNO ₃ 2ml
・ 3rd step: HNO ₃ 1ml
・ 4th step: HClO ₄ 1ml

  Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A1).

[Synthesis Examples 2 to 5]
Except having changed the drying time of the synthesis example 1 as shown in Table 1, it carried out similarly to the synthesis example 1, and obtained polyester resin A (A2)-(A5).
Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resins A (A2) to (A5).

で示されるジカルボン酸ハライド１０．５ｇをジクロロメタンに溶解させ、酸ハロゲン化物溶液を調製した。
また、酸ハロゲン化物溶液とは別に、上記式（２−１）で示されるシロキサン構造を有するジオール９．４ｇおよび上記式（３−１）で示されるジオール５７．０ｇを用いて、合成例１と同様の操作を行い、上記式（Ａ−１０）、（Ａ−２）、（Ｂ−１）および（Ｂ−３）で示される構造単位を有するポリエステル樹脂Ａ（Ａ６）を得た。 [Synthesis Example 6]
Synthesis of polyester resin A (A6) having structural units represented by the above formulas (A-10), (A-2), (B-1) and (B-3) represented by the above formula (1-1) 35.6 g of dicarboxylic acid halide and the following formula (1-2)

A dicarboxylic acid halide represented by the formula (1) (10.5 g) was dissolved in dichloromethane to prepare an acid halide solution.
Separately from the acid halide solution, 9.4 g of the diol having the siloxane structure represented by the above formula (2-1) and 57.0 g of the diol represented by the above formula (3-1) were used, and Synthesis Example 1 The polyester resin A (A6) having the structural unit represented by the above formulas (A-10), (A-2), (B-1) and (B-3) was obtained.

It was 10 mass% when content of the structural unit shown by the said Formula (A-10) and (A-2) with respect to the total mass of the polyester resin A (A6) was computed. Moreover, the weight average molecular weight of the polyester resin A (A6) was 92,000.
Moreover, it was 114 ppm when the amount of volatile siloxane of the polyester resin A was computed.

  Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A6).

[Synthesis Examples 7 to 10]
Except having changed the drying time of the synthesis example 6 as shown in Table 1, it carried out similarly to the synthesis example 6, and obtained polyester resin A (A7)-(A10).

  Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resins A (A7) to (A10).

[Synthesis Example 11]
The amount of dicarboxylic acid halides (1-1) and (1-2) used in Synthesis Example 6 and the amount of diol compound used in the synthesis of (2-1) and (3-1) is different from that of polyester resin A6 (A A polyester resin A (A11) was synthesized in the same manner as in Synthesis Example 6 except that adjustment was made so that a resin having the content of the structural units represented by -10) and (A-2) was obtained.

It was 20 mass% when content of the structural unit shown by the said Formula (A-10) and (A-2) with respect to the total mass of the polyester resin A (A11) was computed. Moreover, the weight average molecular weight of the polyester resin A (A11) was 91,000.
Moreover, it was 146 ppm when the amount of volatile siloxane of the polyester resin A was computed.

  Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A6).

[Synthesis Example 12]
A polyester resin A (A12) was obtained in the same manner as in Synthesis Example 11 except that the drying time of Synthesis Example 11 was changed as shown in Table 1.
Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A12).

[Synthesis Example 13]
The amount of dicarboxylic acid halides (1-1) and (1-2) used in Synthesis Example 6 and the diol compounds used in the synthesis of (2-1) and (3-1) has a molecular weight different from that of the polyester resin A6. Except having adjusted so that resin might be obtained, operation similar to the synthesis example 6 was performed, and the polyester resin A (A13) was synthesize | combined.

It was 10 mass% when content of the structural unit shown by the said Formula (A-10) and (A-2) with respect to the total mass of the polyester resin A (A13) was computed. Moreover, the weight average molecular weight of the polyester resin A (A13) was 58,000.
Moreover, it was 99 ppm when the amount of volatile siloxane of the polyester resin A was computed.

  Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A13).

[Synthesis Example 14]
A polyester resin A (A14) was obtained in the same manner as in Synthesis Example 13 except that the drying time of Synthesis Example 13 was changed as shown in Table 1.
Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A14).

[Synthesis Example 15]
Molecular weights different from the polyester resins A6 and A13 in the amounts used in the synthesis of the dicarboxylic acid halides (1-1) and (1-2) and the diol compounds (2-1) and (3-1) used in Synthesis Example 6 A polyester resin A (A15) was synthesized by performing the same operation as in Synthesis Example 6 except that adjustment was made so as to obtain a resin having the following.

It was 10 mass% when content of the structural unit shown by the said Formula (A-10) and (A-2) with respect to the total mass of the polyester resin A (A15) was computed. Moreover, the weight average molecular weight of the polyester resin A (A15) was 140,000.
Moreover, it was 110 ppm when the amount of volatile siloxane of the polyester resin A was computed.

  Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A15).

[Synthesis Example 16]
A polyester resin A (A16) was obtained in the same manner as in Synthesis Example 15 except that the drying time in Synthesis Example 15 was changed as shown in Table 1.
Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A16).

で示されるシロキサン構造を有するジオール９．７ｇおよび上記式（３−１）で示されるジオール５７．０ｇを用いて、合成例１と同様の操作を行い、上記式（Ａ−１１）、（Ａ−３）、（Ｂ−１）および（Ｂ−３）で示される構造単位を有するポリエステル樹脂Ａ（Ａ１７）を得た。 [Synthesis Example 17]
Synthesis of polyester resin A (A17) having structural units represented by the above formulas (A-11), (A-3), (B-1) and (B-3) represented by the above formula (1-1) An acid halide solution was prepared by dissolving 35.4 g of dicarboxylic acid halide and 10.4 g of dicarboxylic acid halide represented by the above formula (1-2) in dichloromethane.
In addition to the acid halide solution, the following formula (2-2)

Using 9.7 g of the diol having a siloxane structure represented by formula (5) and 57.0 g of the diol represented by formula (3-1) above, the same operation as in Synthesis Example 1 was performed, and the above formulas (A-11), (A -3), polyester resin A (A17) having structural units represented by (B-1) and (B-3) was obtained.

It was 10 mass% when content of the structural unit shown by the said Formula (A-11) and (A-3) with respect to the total mass of the polyester resin A (A17) was computed. Moreover, the weight average molecular weight of the polyester resin A (A17) was 88,000.
Moreover, it was 136 ppm when the amount of volatile siloxane of the polyester resin A was computed.

  Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A17).

[Synthesis Example 18]
A polyester resin A (A18) was obtained in the same manner as in Synthesis Example 17 except that the drying time of Synthesis Example 17 was changed as shown in Table 1.
Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A18).

[Synthesis Example 19]
Polyester resin A (A19) having structural units represented by the above formulas (A-10), (A-2), (A-11), (A-3), (B-1) and (B-3) Synthesis of 35.5 g of dicarboxylic acid halide represented by the above formula (1-1) and 10.5 g of dicarboxylic acid halide represented by the above formula (1-2) were dissolved in dichloromethane to prepare an acid halide solution.
Separately from the acid halide solution, 5.7 g of a diol having a siloxane structure represented by the above formula (2-1), 5.2 g of a diol having a siloxane structure represented by the above formula (2-2), and the above formula The same operation as in Synthesis Example 1 was performed using 56.9 g of the diol represented by (3-1), and the above formulas (A-10), (A-2), (A-11), (A-3) ), Polyester resin A (A19) having structural units represented by (B-1) and (B-3) was obtained.

The content of the structural unit represented by the above formulas (A-10), (A-2), (A-11), and (A-3) relative to the total mass of the polyester resin A (A19) was calculated to be 10 masses. %Met. Moreover, the weight average molecular weight of the polyester resin A (A19) was 90,000.
Moreover, it was 122 ppm when the amount of volatile siloxane was computed.

  Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A19).

[Synthesis Example 20]
A polyester resin A (A20) was obtained in the same manner as in Synthesis Example 19 except that the drying time of Synthesis Example 19 was changed as shown in Table 1.
Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A20).

で示されるジカルボン酸ハライド２０．２ｇをジクロロメタンに溶解させ、酸ハロゲン化物溶液を調製した。
また、酸ハロゲン化物溶液とは別に、上記式（２−１）で示されるシロキサン構造を有するジオール９．２ｇおよび上記式（３−１）で示されるジオール６４．９ｇを用いて、合成例１と同様の操作を行い、上記式（Ａ−２）、（Ａ−６）、（Ｂ−１）および（Ｂ−２）で示される構造単位を有するポリエステル樹脂Ａ（Ａ２１）を得た。 [Synthesis Example 21]
Synthesis of polyester resin A (A21) having structural units represented by the above formulas (A-2), (A-6), (B-1), and (B-2) represented by the above formula (1-2) 20.2 g of dicarboxylic acid halide and the following formula (1-3)

An acid halide solution was prepared by dissolving 20.2 g of a dicarboxylic acid halide represented by the formula (2) in dichloromethane.
Separately from the acid halide solution, 9.2 g of the diol having the siloxane structure represented by the above formula (2-1) and 64.9 g of the diol represented by the above formula (3-1) were used, and Synthesis Example 1 The polyester resin A (A21) having the structural unit represented by the above formulas (A-2), (A-6), (B-1) and (B-2) was obtained.

It was 10 mass% when content of the structural unit shown by the said Formula (A-2) and (A-6) with respect to the total mass of the polyester resin A (A21) was computed. Moreover, the weight average molecular weight of the polyester resin A (A21) was 92,000.
Moreover, it was 102 ppm when the amount of volatile siloxane of the polyester resin A was computed.

  Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A21).

[Synthesis Example 22]
A polyester resin A (A22) was obtained in the same manner as in Synthesis Example 21 except that the drying time of Synthesis Example 21 was changed as shown in Table 1.
Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A22).

[Synthesis Example 23]
A polyester resin A (A23) was obtained in the same manner as in Synthesis Example 6 except that the drying time in Synthesis Example 6 was changed to 2 hours.
It was 648 ppm when the amount of volatile siloxane of the polyester resin A was computed.
Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A23).

[Synthesis Example 24]
A polyester resin A (A24) was obtained in the same manner as in Synthesis Example 13 except that the drying time in Synthesis Example 13 was changed to 2 hours.
It was 525 ppm when the amount of volatile siloxane of the polyester resin A was computed.
Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A24).
[Synthesis Example 25]

A polyester resin A (A25) was obtained in the same manner as in Synthesis Example 15 except that the drying time in Synthesis Example 15 was changed to 2 hours.
It was 779 ppm when the amount of volatile siloxane of the polyester resin A was computed.
Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A25).

[Synthesis Example 26]
A polyester resin A (A26) was obtained in the same manner as in Synthesis Example 19 except that the drying time of Synthesis Example 19 was changed to 2 hours.
It was 688 ppm when the amount of volatile siloxane of the polyester resin A was computed.
Table 2 shows the volatile siloxane amount, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A26).

[Synthesis Example 27]
A polyester resin A (A27) was obtained in the same manner as in Synthesis Example 21, except that the drying time in Synthesis Example 21 was changed to 2 hours.
It was 703 ppm when the amount of volatile siloxane of the polyester resin A was computed.
Table 2 shows the volatile siloxane content, acid value, catalyst content, DEDA content, alkali metal content, and weight average molecular weight of the synthesized polyester resin A (A27).

  In Table 1, “Formula (A)” represents the structural unit represented by Formula (A). When the structural unit represented by the formula (A) is mixed and used, the type and mixing ratio of the structural unit are shown. “Formula (B)” represents the structural unit represented by Formula (B). When the structural unit represented by the formula (B) is mixed and used, the type and mixing ratio of the structural unit are shown. “Drying time” indicates the time of the resin drying process at 165 ° C.

表２中、「ＮＤ」は測定の検出限界以下であることを示す。

In Table 2, “ND” indicates that it is below the detection limit of measurement.

The charge transport layer according to the present invention may contain polyester resin A and at least one of polyester resin C and polycarbonate resin D. Further, other resins may be mixed and used.
Other resins that may be used in combination include acrylic resins, styrene resins, polyester resins, and polycarbonate resins.

(Charge transport material)
The charge transport layer contains a charge transport material. Examples of the charge transport material include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, butadiene compounds, enamine compounds, and the like. These charge transport materials may be used alone or in combination of two or more. Among these, it is preferable to use a triarylamine compound as a charge transport material from the viewpoint of improving electrophotographic characteristics. Moreover, it is preferable that the compound used as a charge transport material does not contain a fluorine atom.

Specific examples of the charge transport material are shown below.

  The charge transport layer can be formed by a coating film of a coating solution for charge transport layer obtained by dissolving polyester resin A and a charge transport material in a solvent.

  The ratio between the charge transport material and the resin is preferably in the range of 4:10 to 20:10 (mass ratio), and more preferably in the range of 5:10 to 12:10 (mass ratio).

  Examples of the solvent used in the charge transport layer coating solution include ketone solvents, ester solvents, ether solvents, and aromatic hydrocarbon solvents. These solvents may be used alone or in combination of two or more. Among these solvents, it is preferable to use an ether solvent or an aromatic hydrocarbon solvent from the viewpoint of the solubility of the resin.

  The film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 35 μm or less.

  In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer as necessary.

Next, the configuration of the electrophotographic photosensitive member of the present invention will be described.
The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer. The charge transport layer is an electrophotographic photosensitive member whose surface layer (uppermost layer) is an electrophotographic photosensitive member.
In general, a cylindrical electrophotographic photosensitive member in which a photosensitive layer is formed on a cylindrical support is widely used as the electrophotographic photosensitive member. However, a belt shape, a sheet shape, or the like may be used. It is.

[Support]
As the support, one having conductivity (conductive support) is preferable, and a metal support such as aluminum, aluminum alloy, and stainless steel can be used. In the case of a support made of aluminum or aluminum alloy, ED tube, EI tube, and these are cut, electrolytic composite polishing (electrolysis with electrode having electrolytic action and polishing with grinding stone having polishing action), wet or dry type A honing-treated support can also be used. Moreover, what formed the film by vacuum deposition of aluminum, an aluminum alloy, or an indium oxide tin oxide alloy on a metal support body and a resin support body can also be used. The surface of the support may be subjected to cutting treatment, roughening treatment, alumite treatment, or the like.

  In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated in a resin, or a plastic having a conductive resin can also be used.

  A conductive layer may be provided between the support and the undercoat layer or charge generation layer, which will be described later, for the purpose of suppressing interference fringes due to scattering of laser light or the like and covering the scratches on the support. This is a layer formed using a conductive layer coating liquid in which conductive particles are dispersed in a resin. Examples of the conductive particles include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, and metal oxide powder such as conductive tin oxide and ITO. Can be mentioned.

  Examples of the resin used for the conductive layer include polyester resin, polycarbonate resin, polyvinyl butyral, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

  Examples of the solvent for the conductive layer coating solution include ether solvents, alcohol solvents, ketone solvents, and aromatic hydrocarbon solvents.

  The thickness of the conductive layer is preferably 0.2 μm or more and 40 μm or less, more preferably 1 μm or more and 35 μm or less, and even more preferably 5 μm or more and 30 μm or less.

[Undercoat layer]
In the electrophotographic photoreceptor of the present invention, an undercoat layer may be provided between the support or conductive layer and the charge generation layer.
The undercoat layer can be formed by applying a coating solution for an undercoat layer containing a resin on the conductive layer and drying or curing it.

  Examples of the resin used for the undercoat layer include polyacrylic acids, methylcellulose, ethylcellulose, polyamide resin, polyimide resin, polyamideimide resin, polyamic acid resin, melamine resin, epoxy resin, polyurethane resin, and polyolefin resin. The resin for the undercoat layer is preferably a thermoplastic resin. Specifically, a thermoplastic polyamide resin or a polyolefin resin is preferable. The polyamide resin is preferably a low crystalline or non-crystalline copolymer nylon that can be applied in a solution state. The polyolefin resin is preferably in a state usable as a particle dispersion. Furthermore, it is preferable that the polyolefin resin is dispersed in an aqueous medium.

  The thickness of the undercoat layer is preferably 0.05 μm or more and 7 μm or less, and more preferably 0.1 μm or more and 2 μm or less.

  The undercoat layer may contain semiconductive particles, an electron transport material, or an electron accepting material.

(Charge generation layer)
A charge generation layer is provided on the support, the conductive layer, or the undercoat layer.
Examples of the charge generating material used in the electrophotographic photoreceptor of the present invention include azo pigments, phthalocyanine pigments, indigo pigments and perylene pigments. These charge generation materials may be used alone or in combination of two or more. Among these, metal phthalocyanines such as oxytitanium phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine are particularly preferable because of their high sensitivity.

  Examples of the resin used for the charge generation layer include polycarbonate resin, polyester resin, butyral resin, polyvinyl acetal resin, acrylic resin, vinyl acetate resin, and urea resin. Among these, a butyral resin is particularly preferable. These can be used singly or in combination of two or more as a mixture or copolymer.

  The charge generation layer can be formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material together with a resin and a solvent, and drying the obtained coating film.

  Examples of the dispersion method include a method using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, and a roll mill.

  The ratio between the charge generating material and the resin is preferably in the range of 1:10 to 10: 1 (mass ratio), and more preferably in the range of 1: 1 to 3: 1 (mass ratio).

  Examples of the solvent used in the charge generation layer coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

  The thickness of the charge generation layer is preferably from 0.01 μm to 5 μm, and more preferably from 0.1 μm to 2 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary. In addition, in order to prevent the flow of charges in the charge generation layer from stagnation, the charge generation layer may contain an electron transport material or an electron accepting material.

(Charge transport layer)
The above-described charge transport layer is provided on the charge generation layer.

  Various additives can be added to each layer of the electrophotographic photoreceptor of the present invention. Examples of the additive include deterioration preventing agents such as antioxidants, ultraviolet absorbers, and light resistance stabilizers, and fine particles such as organic fine particles and inorganic fine particles. Examples of the deterioration inhibitor include hindered phenol antioxidants, hindered amine light resistance stabilizers, sulfur atom-containing antioxidants, and phosphorus atom-containing antioxidants. Examples of the organic fine particles include polymer resin particles such as fluorine atom-containing resin particles, polystyrene fine particles, and polyethylene resin particles. Examples of the inorganic fine particles include metal oxides such as silica and alumina.

  When applying the coating liquid for each of the above layers, a coating method such as a dip coating method (dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, or a blade coating method can be used. .

  Further, an uneven shape (concave shape, convex shape) may be formed on the surface of the charge transport layer which is the surface layer of the electrophotographic photosensitive member. A known method can be adopted as a method for forming the uneven shape. As a forming method, a method of forming a concave shape by spraying abrasive particles on the surface of the charge transport layer, a method of forming a concavo-convex shape by press-contacting a mold having a concave and convex shape on the surface of the charge transport layer, coating Examples include a method of forming a concave shape by condensing the coating surface of the surface layer coating liquid and drying it, a method of forming a concave shape by irradiating the surface of the charge transport layer with laser light, and the like. . Among these, a method of forming a concavo-convex shape by pressing a mold having a concavo-convex shape on the surface of the surface layer of the electrophotographic photosensitive member is preferable. Moreover, after condensing the coating-film surface of the apply | coated liquid for surface layers, the method of forming a concave shape by making it dry is preferable.

[Electrophotographic equipment]
FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having an electrophotographic photosensitive member.
In FIG. 1, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is rotationally driven in a direction of an arrow about a shaft 2 at a predetermined peripheral speed. The surface of the electrophotographic photosensitive member 1 that is driven to rotate is uniformly charged to a predetermined positive or negative potential by a charging unit (primary charging unit: charging roller or the like) 3 during the rotation process. Next, exposure light (image exposure light) 4 output from exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1.

  The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed by reversal development with toner contained in the developer of the developing unit 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photosensitive member 1 is sequentially transferred onto a transfer material (such as paper) P by a transfer bias from a transfer unit (such as a transfer roller) 6. The transfer material P is taken out from the transfer material supply means (not shown) between the electrophotographic photoreceptor 1 and the transfer means 6 (contact portion) in synchronization with the rotation of the electrophotographic photoreceptor 1 and fed. Is done.

  The transfer material P that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member 1 and introduced into the fixing means 8 to receive the image fixing, and is printed out as an image formed product (print, copy). Is done.

  The surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by receiving a developer (toner) remaining after transfer by a cleaning means (cleaning blade or the like) 7. Next, after being subjected to charge removal processing by pre-exposure light (not shown) from pre-exposure means (not shown), it is repeatedly used for image formation. As shown in FIG. 1, when the charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not necessarily required.

  A plurality of components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6 and the cleaning unit 7 are selected, housed in a container, and integrally coupled as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 1, an electrophotographic photosensitive member 1, a charging unit 3, a developing unit 5 and a cleaning unit 7 are integrally supported to form a cartridge, and an electrophotographic apparatus is provided using a guide unit 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is detachable from the main body.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”.

[Example 1]
An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as a support (conductive support).
Next, 10 parts of SnO ₂ -coated barium sulfate particles (conductive particles), 2 parts of titanium oxide particles (resistance resistance pigment), 6 parts of phenol resin, 0.001 part of silicone oil (leveling agent) and 4 parts of methanol / A conductive layer coating solution was prepared using a mixed solvent of 16 parts of methoxypropanol.
This conductive layer coating solution was dip-coated on a support and cured (thermosetting) at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm.

Next, an undercoat layer coating solution was prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol.
The undercoat layer coating solution was applied onto the conductive layer by dip coating, and dried at 100 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.7 μm.

  Next, strong peaks at 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction 10 parts of a crystalline form of hydroxygallium phthalocyanine (charge generating substance) having It was mixed with 250 parts of cyclohexanone and 5 parts of polyvinyl butyral resin (trade name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 1 in a 23 ± 3 ° C. atmosphere in a sand mill using glass beads having a diameter of 1 mm. Time dispersed. After dispersion, a coating solution for charge generation layer was prepared by adding 250 parts of ethyl acetate. This charge generation layer coating solution was dip-coated on the undercoat layer, and the resulting coating film was dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.26 μm.

Next, 9 parts of the compound represented by formula (E-1) (charge transporting substance), 1 part of the compound represented by formula (E-5) (charge transporting substance), and polyester resin A (A1) synthesized in Synthesis Example 1 ) 3 parts and polyester resin C (C1) (containing the structural unit represented by the above formula (C-1) and the structural unit represented by the above formula (C-2) in a ratio of 5: 5. Weight average molecular weight 120 , 000) was dissolved in a mixed solvent of 30 parts of dimethoxymethane and 50 parts of o-xylene to prepare a coating solution for a charge transport layer. The charge transport layer coating solution was dip coated on the charge generation layer, and the resulting coating film was dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 16 μm.
In this manner, an electrophotographic photoreceptor having a charge transport layer as a surface layer was produced.

Next, evaluation will be described.
The evaluation was performed by measuring the amount of fluctuation (potential fluctuation) of the bright part potential when the 3,000 sheets were repeatedly used.
As an evaluation apparatus, a laser beam printer LBP-5050 manufactured by Canon Inc. was used. Evaluation was performed in an environment of a temperature of 23 ° C. and a relative humidity of 50%. The exposure amount (image exposure amount) of the 780 nm laser light source of the evaluation apparatus was set so that the light amount on the surface of the electrophotographic photosensitive member was 0.3 μJ / cm ² . To measure the surface potential (dark part potential and bright part potential) of the electrophotographic photosensitive member, replace the jig and the developing device fixed so that the potential measuring probe is positioned 130 mm from the end of the electrophotographic photosensitive member. Then, it was carried out at the developing unit position. The dark part potential of the non-exposed part of the electrophotographic photosensitive member was set to be −450 V, and the bright part potential that was light-attenuated from the dark part potential by irradiation with laser light was measured. In addition, 3,000 sheets of image output were continuously performed using A4 size plain paper, and the amount of fluctuation of the bright portion potential before and after the evaluation was evaluated. A test chart having a printing ratio of 5% was used.
The results are shown in Table 3.

[Examples 2 to 22]
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the polyester resin A (A1) in the charge transport layer was changed as shown in Table 3 in Example 1, and potential fluctuation was evaluated. The results are shown in Table 3.

Example 23
In Example 1, the polyester resin A (A1) of the charge transport layer is changed to the polyester resin (A7), and the polyester resin C (C1) is converted to a polycarbonate resin D (D1) composed of the structural unit represented by the above formula (D-1). The electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the potential fluctuation was changed, and the potential fluctuation was evaluated. The results are shown in Table 3. The weight average molecular weight of the polycarbonate resin D (D1) was 140,000.

Example 24
In Example 1, the polyester resin A (A1) of the charge transport layer is changed to the polyester resin (A7), and the polyester resin C (C1) is replaced with the structural unit represented by the above formula (C-1) and the above formula (C-3). The electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the polyester resin C (C2) having the structural unit represented by 3) was changed to a ratio of 3: 7, and potential fluctuations were evaluated. The results are shown in Table 3. The weight average molecular weight of the polyester resin C (C2) was 130,000.

Example 25
In Example 1, the same procedure as in Example 1 except that 3 parts of the polyester resin A (A1) in the charge transport layer was changed to 10 parts of the polyester resin (A7) and the polyester resin C (C1) was removed. Photoconductors were prepared and potential fluctuations were evaluated. The results are shown in Table 3.

[Comparative Examples 1-5]
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the polyester resin A (A1) in the charge transport layer was changed as shown in Table 3 in Example 1, and potential fluctuation was evaluated. The results are shown in Table 3.

  “Volatile siloxane amount (ppm)” in Table 3 indicates the amount of volatile siloxane contained in the polyester resin A. “Other binder resin” in Table 3 represents a resin other than the polyester resin A contained in the charge transport layer.

  If the potential fluctuation during repeated use is large, the image density tends to decrease. From the examination, it has been found in this evaluation that the image quality can be stably maintained if the potential fluctuation is 40 V or less.

  According to a comparison between the examples and the comparative examples, the electrophotographic photoreceptor characterized by containing the polyester resin A having a specific structural unit having a volatile siloxane amount of 150 ppm or less is excellent in potential stability. I understand.

  Also, from Table 2, the polyester resins A (A1) to (A22) included in the examples are more acid values, catalyst contents, and DEDA than the polyester resins A (A23) to (A27) included in the comparative examples. It turns out that the numerical value of content is small. From Table 2 and Table 3, it is considered that the small numerical values of acid value, catalyst content, and DEDA content also contribute to the improvement of potential stability.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means P Transfer material

Claims (6)

In an electrophotographic photosensitive member having a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer, wherein the charge transport layer is a surface layer.
Polyester resin A in which the charge transport layer has a charge transport material, a structural unit represented by the following formula (A) and a structural unit represented by the following formula (B), and the amount of volatile siloxane is 150 ppm or less. And an electrophotographic photosensitive member.

(In Formula (A), X ¹ represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom. R ¹¹ and R ¹² are Each independently represents a methyl group, an ethyl group, or a phenyl group, n represents the number of repetitions in parentheses, and the average value of n in the polyester resin A is 20 or more and 120 or less.)

(In formula (B), X ² represents an m-phenylene group, a p-phenylene group, or a divalent group in which two p-phenylene groups are bonded via an oxygen atom.)   The electrophotographic photosensitive member according to claim 1, wherein the content of the structural unit represented by the formula (A) with respect to the total mass of the polyester resin A is 6% by mass or more and 40% by mass or less.   The electrophotographic photosensitive member according to claim 1, wherein the content of the structural unit represented by the formula (B) with respect to the total mass of the polyester resin A is 60% by mass or more. The charge transport layer contains the polyester resin A, and further comprises a polyester resin C having a structural unit represented by the following formula (C) and a polycarbonate resin D having a structural unit represented by the following formula (D). The electrophotographic photosensitive member according to claim 1, comprising at least one resin selected from the above.

(In formula (C), R ^{31 to} R ³⁸ each independently represents a hydrogen atom or a methyl group. X ³ represents an m-phenylene group, a p-phenylene group, or two p-phenylene groups as oxygen. Y ² represents a single bond, a methylene group, an ethylidene group, or a propylidene group.

(In formula (D), R ^{41 to} R ⁴⁸ each independently represent a hydrogen atom or a methyl group. Y ⁴ represents a methylene group, an ethylidene group, a propylidene group, a phenylethylidene group, a cyclohexylidene group, or Indicates an oxygen atom.)   An electrophotographic photosensitive member according to any one of claims 1 to 4, and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, and a cleaning means, are integrally supported, and electrophotographic A process cartridge which is detachable from the apparatus main body.   An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an exposure unit, a developing unit, and a transfer unit.

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