JP2018185373A - Electrophotographic photoreceptor, process cartridge, and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that has high durability and is highly effective in suppressing a photo memory.SOLUTION: An electrophotographic photoreceptor has a surface layer that contains a charge transport material and a polyester resin having a specific structure.SELECTED DRAWING: None

Description

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

  In the electrophotographic process, in recent years, there is an increasing demand for extending the life and speed of process cartridges and electrophotographic apparatuses. Correspondingly, further improvement in durability is desired for the electrophotographic photosensitive member. There is also a need to improve the causes of image quality degradation such as photo memory.

  When the charge transport layer is a surface layer, durability against electrical and mechanical external forces is required. Therefore, methods using a photoreceptor having a surface layer using a polyester resin having excellent mechanical strength have been studied (Patent Documents 1, 2, and 3).

  Patent Document 1 discloses an electrophotographic photoreceptor using a polyester resin having diphenyl ether dicarboxylic acid as a surface layer. Patent Document 2 discloses an electrophotographic photoreceptor using a polyester resin having a biphenylene structure in addition to diphenyl ether dicarboxylic acid as a surface layer. Further, Patent Document 3 similarly discloses an electrophotographic photoreceptor using, as a surface layer, a polyester resin having a biphenylene structure substituted with 4 methyl groups in addition to diphenyl ether dicarboxylic acid. It is described that any of the electrophotographic photoreceptors has improved durability and electrophotographic characteristics.

Japanese Patent No. 4517964 JP 2009-271112 A Japanese Patent No. 4978711 JP 2007-79555 A

  In the study by the present inventors, the electrophotographic photosensitive member using the conventional polyester resin described in Patent Documents 1 to 3 described above has recently been required to have an effect of suppressing photo memory, although its durability has been improved to some extent. The level was not reached.

  One embodiment of the present invention is directed to providing an electrophotographic photosensitive member having high durability and further having a high effect of suppressing photo memory. Another aspect of the present invention is directed to providing a process cartridge and an electrophotographic apparatus including the electrophotographic photosensitive member.

（一般式（Ｉ）において、Ｘ^１は、２価の基を表す。）

（一般式（ＩＩ）において、Ｘ^２は、単結合、酸素原子、２価の置換または非置換のメチレン基又は２価の置換または非置換のシクロアルキリデン基を示す。Ｒ^１１〜Ｒ^１８は、それぞれ独立に水素原子又はアルキル基を示す。）
該一般式（Ｉ）で示される構造が、式（Ｉ−１）で示される構造を含み、

該一般式（ＩＩ）で示される構造が、一般式（ＩＩ−１）で示される構造を含むことを特徴とする。

（一般式（ＩＩ−１）において、Ｒ^２１〜Ｒ^２８のうち少なくとも５つ以上がアルキル基であり、それ以外が水素原子である。） The electrophotographic photoreceptor according to one embodiment of the present invention contains a charge transport material and a polyester resin in the surface layer,
The polyester resin has a structure represented by the general formula (I) and a structure represented by the general formula (II),

(In the general formula (I), X ¹ represents a divalent group.)

(In General Formula (II), X ² represents a single bond, an oxygen atom, a divalent substituted or unsubstituted methylene group, or a divalent substituted or unsubstituted cycloalkylidene group. R ^{11 to} R ¹⁸ are Each independently represents a hydrogen atom or an alkyl group.)
The structure represented by the general formula (I) includes a structure represented by the formula (I-1),

The structure represented by the general formula (II) includes a structure represented by the general formula (II-1).

(In General Formula (II-1), at least 5 or more of R ^{21 to} R ²⁸ are alkyl groups, and the others are hydrogen atoms.)

  According to one embodiment of the present invention, an electrophotographic photosensitive member having high durability and further high photomemory suppression effect is provided. According to another aspect of the present invention, a process cartridge and an electrophotographic apparatus provided with the electrophotographic photosensitive member are provided.

1 is a diagram illustrating a schematic configuration of a process cartridge and an electrophotographic apparatus including an electrophotographic photosensitive member according to an aspect of the present invention.

（一般式（Ｉ）において、Ｘ^１は、２価の基を表す。）

（一般式（ＩＩ）において、Ｘ^２は、単結合、酸素原子、２価の置換または非置換のメチレン基又は２価の置換または非置換のシクロアルキリデン基を示す。Ｒ^１１〜Ｒ^１８は、それぞれ独立に水素原子又はアルキル基を示す。）
該一般式（Ｉ）で示される構造が、式（Ｉ−１）で示される構造を含み、

該一般式（ＩＩ）で示される構造が、一般式（ＩＩ−１）で示される構造を含むことを特徴とする。

（一般式（ＩＩ−１）において、Ｒ^２１〜Ｒ^２８のうち少なくとも５つ以上がアルキル基であり、それ以外が水素原子である。） Hereinafter, the present invention will be described in detail with reference to preferred embodiments.
The electrophotographic photoreceptor according to one embodiment of the present invention contains a charge transport material and a polyester resin in the surface layer,
The polyester resin has a structure represented by the general formula (I) and a structure represented by the general formula (II),

(In the general formula (I), X ¹ represents a divalent group.)

(In General Formula (II), X ² represents a single bond, an oxygen atom, a divalent substituted or unsubstituted methylene group, or a divalent substituted or unsubstituted cycloalkylidene group. R ^{11 to} R ¹⁸ are Each independently represents a hydrogen atom or an alkyl group.)
The structure represented by the general formula (I) includes a structure represented by the formula (I-1),

The structure represented by the general formula (II) includes a structure represented by the general formula (II-1).

(In General Formula (II-1), at least 5 or more of R ^{21 to} R ²⁸ are alkyl groups, and the others are hydrogen atoms.)

  When the above polyester resin is used for the surface layer containing the charge transport material, the present inventors speculate as follows why the durability and the effect of suppressing photo memory are compatible at a high level. doing.

  In order to obtain high durability of the electrophotographic photoreceptor, it is considered that a resin material having a functional group contributing to high stacking property and rigidity such as a phenylene group is preferably used for the surface layer. However, in the surface layer containing the charge transport material, the charge transport material is considered to partially aggregate due to the stacking property and rigidity of the resin. As a result, it is presumed that the charge tends to stay and the suppression of the photo memory becomes insufficient.

  Therefore, an attempt was made to improve the photomemory by introducing a bulky structure represented by the general formula (II-1) into the resin chain, but only the structure represented by the general formula (II-1) was introduced. However, it was not possible to achieve both high durability and suppression of photo memory.

  The electrophotographic photoreceptor according to one embodiment of the present invention uses, for the surface layer, a resin in which the structure represented by the general formula (II-1) and the structure represented by the formula (I-1) are introduced in the same chain. . The resin in which the structure represented by the general formula (II-1) and the structure represented by the formula (I-1) are introduced in the same chain achieves both a bulky structure and rigidity and flexibility. It has a structure. The bulkiness in the side chain of the formula (II-1) structure is considered to further enhance the flexibility of the formula (I-1) structure. As a result, the degree of freedom of the charge transport material is increased, and it is considered that the photo memory can be effectively suppressed without impairing high durability by optimally arranging the charge transport material in the surface layer. From the above, it is considered that the electrophotographic photosensitive member according to one embodiment of the present invention can achieve both the durability and the effect of suppressing the photo memory at a high level.

  The polyester resin of the present invention has a structure represented by the formula (I-1) as a structure represented by the general formula (I), and a structure represented by the general formula (II-1) as a structure represented by the general formula (II). By having the structure shown, the effects of the present invention can be obtained. The proportion of the structure represented by the formula (I-1) in the structure represented by the general formula (I) is preferably 30 mol% or more. The ratio of the structure represented by the formula (I-1) in the structure represented by the general formula (I) is more preferably 70 mol% or more. In addition, the ratio of the structure represented by the general formula (II-1) to the structure represented by the general formula (II) in the polyester resin is 30 mol% or more. It is preferable in terms of both suppression. In particular, the ratio of the structure represented by the formula (I-1) in the structure represented by the general formula (I) is 70 mol% or more and the structure represented by the general formula (II) occupies the general formula. The ratio of the structure represented by (II-1) is preferably 30 mol% or more. Satisfying such conditions makes it possible to achieve both durability and suppression of photo memory at a particularly high level. The ratio of the structure represented by the general formula (II-1) to the structure represented by the general formula (II) in the polyester resin is more preferably 70 mol% or more.

Moreover, the polyester resin may further have a structure represented by the general formula (I) other than the structure represented by the formula (I-1). Specific examples include structures derived from carboxylic acids such as terephthalic acid, isophthalic acid, biphenyl dicarboxylic acid, aliphatic dicarboxylic acid, and naphthalenedicarboxylic acid. Specific examples include the following structural examples.

  Among these, copolymerization with the terephthalic acid structure represented by the formula (I-2) is preferable from the viewpoint of maintaining high charge mobility. The copolymerization form may be any form such as block copolymerization, random copolymerization, and alternating copolymerization.

Next, specific examples of the structure represented by the general formula (II-1) are shown below.

  Among these, the structure represented by the formula (II-1-2) is more preferable in terms of achieving both high durability and suppression of photo memory.

（一般式（ＩＩ−２）において、Ｒ^{３１〜３４}は、それぞれ独立に水素原子又はアルキル基を示す。Ｙ^１は、単結合、酸素原子、２価の置換または非置換のメチレン基又は２価の置換または非置換のアルキリデン基を示す。） Moreover, the polyester resin may further have a structure represented by the general formula (II-2) as the structure represented by the general formula (II). That is, the structure represented by the general formula (II) has a structure represented by the general formula (II-1) and a structure represented by the general formula (II-2).

(In General Formula (II-2), R ^{31 to 34} each independently represents a hydrogen atom or an alkyl group. Y ¹ represents a single bond, an oxygen atom, a divalent substituted or unsubstituted methylene group or a divalent group. Represents a substituted or unsubstituted alkylidene group.)

Specific examples of the structure represented by the general formula (II-2) are shown below.

  In the present invention, the copolymerization form may be any form such as block copolymerization, random copolymerization, alternating copolymerization, etc., but random copolymerization is particularly preferable from the viewpoint of obtaining high durability.

  The surface layer may use other resins as the binder resin in addition to the polyester resin. Examples of other resins include polycarbonate resin, polymethacrylic ester resin, polysulfone resin, and polystyrene resin. Other resins may be blended or copolymerized. When using other resin, it is preferable that the mass of the polyester resin in this invention is 50 mass% or more with respect to the mass of all the binder resins.

  The weight average molecular weight of the binder resin is preferably 60,000 or more and 200,000 or less, and more preferably 80,000 or more and 150,000 or less. At this time, the weight average molecular weight of the resin is a polystyrene equivalent weight average molecular weight measured by the method described in Patent Document 4.

[Electrophotographic photoreceptor]
The electrophotographic photoreceptor of the present invention has a surface layer. Moreover, it is preferable to have a support and a photosensitive layer. The photosensitive layer of the electrophotographic photoreceptor is mainly classified into (1) a multilayer type photosensitive layer and (2) a single layer type photosensitive layer. (1) The laminated photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. (2) The single-layer type photosensitive layer contains both a charge generation material and a charge transport material. In the present invention, (1) in the case of a multilayer type photosensitive layer, the charge transport layer containing a charge transport material is a surface layer, and (2) in the case of a single layer type photosensitive layer, a charge generating material and a charge transport material are combined. The photosensitive layer contained together becomes the surface layer.

  Examples of the method for producing the electrophotographic photoreceptor of the present invention include a method in which a coating solution for each layer described later is prepared, applied in the order of desired layers, and dried. At this time, examples of the coating method of the coating liquid include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, dip coating is preferable from the viewpoints of efficiency and productivity. Hereinafter, the support and each layer will be described.

<Support>
In the present invention, the electrophotographic photoreceptor preferably has a support. In the present invention, the support is preferably a conductive support having conductivity. Moreover, examples of the shape of the support include a cylindrical shape, a belt shape, and a sheet shape. Among these, a cylindrical support is preferable. Further, the surface of the support may be subjected to electrochemical treatment such as anodic oxidation, blast treatment, cutting treatment or the like.

As the material for the support, metal, resin, glass and the like are preferable.
Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support using aluminum is preferable.
Further, the support made of resin or glass may be imparted with conductivity by a treatment such as mixing or coating with a conductive material.

<Conductive layer>
In the present invention, a conductive layer may be provided on the support. By providing the conductive layer, it is possible to conceal scratches and irregularities on the surface of the support and to control light reflection on the surface of the support.
The conductive layer preferably contains conductive particles and a resin.

Examples of the material of the conductive particles include metal oxide, metal, carbon black and the like.
Examples of the metal oxide include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, and bismuth oxide. Examples of the metal include aluminum, nickel, iron, nichrome, copper, zinc, silver and the like.
Among these, it is preferable to use a metal oxide as the conductive particles, and it is particularly preferable to use titanium oxide, tin oxide, or zinc oxide.

  When a metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or an element such as phosphorus or aluminum or an oxide thereof may be doped into the metal oxide.

  Further, the conductive particles may have a laminated structure including core material particles and a coating layer that covers the particles. Examples of the core material particles include titanium oxide, barium sulfate, and zinc oxide. Examples of the coating layer include metal oxides such as tin oxide.

  Moreover, when using a metal oxide as electroconductive particle, it is preferable that the volume average particle diameters are 1 nm or more and 500 nm or less, and it is more preferable that they are 3 nm or more and 400 nm or less.

  Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, alkyd resin, and the like.

  The conductive layer may further contain a masking agent such as silicone oil, resin particles, and titanium oxide.

  The average film thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

  The conductive layer can be formed by preparing a coating solution for a conductive layer containing the above-described materials and solvent, forming this coating film on a support, and drying it. Examples of the solvent used for the coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Examples of the dispersion method for dispersing the conductive particles in the coating liquid for the conductive layer include a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

<Underlayer>
In the present invention, an undercoat layer may be provided on the support or the conductive layer. By providing the undercoat layer, the adhesion function between the layers can be enhanced, and a charge injection blocking function can be provided.

  The undercoat layer preferably contains a resin. Moreover, you may form an undercoat layer as a cured film by superposing | polymerizing the composition containing the monomer which has a polymerizable functional group.

  Polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin , Polyamic acid resin, polyimide resin, polyamideimide resin, cellulose resin and the like.

  As the polymerizable functional group that the monomer having a polymerizable functional group has, an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, Examples thereof include a carboxylic acid anhydride group and a carbon-carbon double bond group.

  The undercoat layer may further contain an electron transport material, a metal oxide, a metal, a conductive polymer, and the like for the purpose of improving electrical characteristics. Among these, it is preferable to use an electron transport material and a metal oxide.

  Examples of the electron transport material include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, and boron-containing compounds. . An undercoat layer may be formed as a cured film by using an electron transport material having a polymerizable functional group as the electron transport material and copolymerizing with the monomer having the polymerizable functional group described above.

Examples of the metal oxide include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, and silicon dioxide. Examples of the metal include gold, silver, and aluminum.
The undercoat layer may further contain an additive.

  The average thickness of the undercoat layer is preferably from 0.1 μm to 50 μm, more preferably from 0.2 μm to 40 μm, and particularly preferably from 0.3 μm to 30 μm.

  The undercoat layer is formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, and forming this coating film on the support or conductive layer, followed by drying and / or curing. Can do. Examples of the solvent used for the coating solution include alcohol solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

<Photosensitive layer>
(1) Multilayer Photosensitive Layer In the case of a multilayer photosensitive layer, the electrophotographic photosensitive member includes a charge generation layer containing a charge generation material, a charge transport material, a structure represented by the general formula (I), and a general formula ( And a charge transport layer containing a polyester resin having the structure represented by II).

(1-1) Charge Generation Layer The average film thickness of the charge generation layer is preferably from 0.05 μm to 5 μm, more preferably from 0.05 μm to 1 μm, and from 0.1 μm to 0.3 μm. It is particularly preferred that

  Charge generation materials include azo pigments, perylene pigments, anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives, isoviolanthrone derivatives, indigo derivatives, thioindigo derivatives, phthalocyanine pigments, bisbenzimidazole derivatives Is mentioned. Among these, azo pigments or phthalocyanine pigments are preferable. Among the phthalocyanine pigments, oxytitanium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine are preferable.

  Examples of the binder resin used for the charge generation layer include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic ester, methacrylic ester, vinylidene fluoride, trifluoroethylene, and polyvinyl alcohol. Examples thereof include resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, polysulfone resins, polyphenylene oxide resins, polyurethane resins, cellulose resins, phenol resins, melamine resins, silicon resins, and epoxy resins. Among these, a polyester resin, a polycarbonate resin, and a polyvinyl acetal resin are preferable, and a polyvinyl acetal resin is particularly preferable.

  The content of the charge generation material in the charge generation layer is preferably 30% by mass to 90% by mass and more preferably 50% by mass to 80% by mass with respect to the total mass of the charge generation layer. preferable.

  In the charge generation layer, the mass ratio of the charge generation material to the binder resin (charge generation material / binder resin) is preferably in the range of 10/1 to 1/10, and is preferably 5/1 to 1/5. A range is more preferable.

  The charge generation layer can be formed by forming a coating film of a coating solution for a charge generation layer prepared by mixing a charge generation material and a binder resin in a solvent and drying the coating film. 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.

(1-2) Charge Transport Layer The 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.

Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and triphenylamine. In addition, examples of the charge transport material include polymers having groups derived from these compounds in the main chain or side chain. Among these, a triarylamine compound or a benzidine compound is preferable in terms of potential stability during repeated use. Moreover, the charge transport material may contain a plurality of types. Specific examples of the charge transport material are shown below.

  The content of the charge transport material in the charge transport layer is preferably 20% by weight to 80% by weight and more preferably 30% by weight to 60% by weight with respect to the total weight of the charge transport layer. preferable.

  The charge transport layer can be formed by forming a coating film of a coating solution for a charge transport layer prepared by dissolving a charge transport material and a binder resin in a solvent, and drying the coating film. Examples of the solvent used in the coating solution for forming the charge transport layer include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

(2) Single-layer type photosensitive layer In the case of a single-layer type photosensitive layer, the photosensitive layer includes a charge generation material, a charge transport material, a structure represented by the general formula (I), and a structure represented by the general formula (II). The polyester resin which has this. The photosensitive layer can be formed by forming a coating film of a coating solution for a photosensitive layer prepared by mixing a charge generating substance, a charge transporting substance and a binder resin in a solvent, and drying the coating film. The charge transporting substance and the binder resin are the same as those exemplified in the above “(1) Multilayer type photosensitive layer”.

<Protective layer>
On the surface layer, you may have a protective layer in the range with the effect of this invention. The protective layer preferably contains conductive particles or a charge transport material and a binder resin. Furthermore, the protective layer may contain an additive such as a lubricant. Further, the binder resin itself of the protective layer may have conductivity and charge transport properties. In that case, the protective layer may not contain conductive particles or a charge transport material. The binder resin of the protective layer may be a thermoplastic resin or a curable resin that is cured by heat, light, or radiation (such as an electron beam).

[Process cartridge, electrophotographic equipment]
The process cartridge of the present invention integrally supports the electrophotographic photosensitive member described so far and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, and a cleaning means. It is detachable from the main body.

  The electrophotographic apparatus of the present invention includes the electrophotographic photosensitive member, the charging unit, the exposure unit, the developing unit, and the transfer unit described so far.

  FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge provided with an electrophotographic photosensitive member.

  Reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is driven to rotate at a predetermined peripheral speed in the direction of an arrow about an axis 2. The surface of the electrophotographic photoreceptor 1 is charged to a positive or negative predetermined potential by the charging unit 3. In the drawing, a roller charging method using a roller-type charging member is shown, but a charging method such as a corona charging method, a proximity charging method, and an injection charging method may be adopted. The surface of the charged electrophotographic photosensitive member 1 is irradiated with exposure light 4 from an exposure means (not shown), and an electrostatic latent image corresponding to target image information is formed. The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 is developed with toner accommodated in the developing means 5, and a toner image is formed on the surface of the electrophotographic photosensitive member 1. The toner image formed on the surface of the electrophotographic photoreceptor 1 is transferred to the transfer material 7 by the transfer means 6. The transfer material 7 onto which the toner image has been transferred is conveyed to the fixing means 8, undergoes a toner image fixing process, and is printed out of the electrophotographic apparatus. The electrophotographic apparatus may have a cleaning unit 9 for removing deposits such as toner remaining on the surface of the electrophotographic photosensitive member 1 after transfer. Further, a so-called cleaner-less system may be used in which the above deposits are removed by a developing unit or the like without providing a cleaning unit. The electrophotographic apparatus may have a static elimination mechanism that neutralizes the surface of the electrophotographic photosensitive member 1 with pre-exposure light 10 from pre-exposure means (not shown). Further, in order to attach / detach the process cartridge 11 of the present invention to / from the electrophotographic apparatus main body, a guide means 12 such as a rail may be provided.

  The electrophotographic photosensitive member of the present invention can be used in laser beam printers, LED printers, copiers, facsimiles, and complex machines thereof.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples as long as the gist thereof is not exceeded. In the description of the following examples, “part” is based on mass unless otherwise specified.

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、別途、下記式で示されるジオール９．５ｇ

及び、下記式で示されるジオール３７．６ｇ

を１０％水酸化ナトリウム水溶液に溶解させ、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。 <Synthesis of polyester resin>
(Synthesis Example 1: Synthesis of polyester resin A)
42.2 g of dicarboxylic acid halide represented by the following formula

Was dissolved in dichloromethane to prepare an acid halide solution. Separately, 9.5 g of a diol represented by the following formula

And 37.6 g of a diol represented by the following formula:

Was dissolved in a 10% aqueous sodium hydroxide solution, and 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. P-tert-butylphenol was added as a polymerization regulator during the polymerization reaction. 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, a dichloromethane solution containing the polyester resin A obtained by the polymerization reaction was dropped into methanol with stirring to precipitate a polymer, and this polymer was vacuum-dried to obtain 70.8 g of a polyester resin A. The obtained polyester resin A was a polyester resin having a structure represented by the formula (I-1) and a structure represented by the formula (II-1-1) and the formula (II-2-2). Moreover, the weight average molecular weight of the obtained polyester resin A was 120,000.

(Synthesis Examples 2 to 22)
In the synthesis of the resin in Synthesis Example 1, the types of dicarboxylic acid halides and diols used so that the structural units represented by the general formula (I) and general formula (II) possessed by the synthesized resin are those shown in Table 1. Changed. Otherwise in the same manner as in Synthesis Example 1, polyester resins B to O, CE-1 to CE-7 and P and Q shown in Table 1 were produced.

表１において、樹脂の重量平均分子量は、ポリエステル樹脂のポリスチレン換算重量平均分子量（Ｍｗ）を示す。

In Table 1, the weight average molecular weight of the resin indicates the polystyrene equivalent weight average molecular weight (Mw) of the polyester resin.

  The ratio of the structure contained in the polyester resin in the surface layer can be analyzed by a general analysis method. Moreover, the content rate of the polyester resin of this invention with respect to the total mass of all the resin in a surface layer can be analyzed with a general analysis method. Examples of analysis methods are shown below.

  First, the surface layer of the electrophotographic photoreceptor is dissolved with a solvent. Thereafter, various materials contained in the surface layer are fractionated by a fractionation device capable of separating and recovering each composition component such as size exclusion chromatography and high performance liquid chromatography. The separated polyester resin is subjected to nuclear magnetic resonance spectrum analysis and mass spectrometry to calculate the number of repeating structures and the molar ratio.

  Alternatively, it is hydrolyzed in the presence of an 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 to calculate the number of structural repeats and the molar ratio.

<Manufacture of electrophotographic photoreceptor>
(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,
・ 214 parts of titanium oxide (TiO ₂ ) particles coated with oxygen-deficient tin oxide (SnO ₂ ) as metal oxide particles ・ 132 parts of phenolic resin as a binder (trade name: Pryofen J-325, DIC Corporation) Manufactured, resin solid content: 60% by mass)
-98 parts of 1-methoxy-2-propanol as a solvent is put into a sand mill using 450 parts of glass beads with a diameter of 0.8 mm, the rotation speed: 2000 rpm, the dispersion treatment time: 4.5 hours, the set temperature of the cooling water: Dispersion treatment was performed at 18 ° C. to obtain a dispersion. Glass beads were removed from this dispersion with a mesh (aperture: 150 μm).

Silicone resin particles as a surface roughness imparting material: Tospearl 120 (Momentive Performance Materials Japan G.K., average particle size 2 μm) was added to the dispersion. The addition amount of the silicone resin particles at this time was 10% by mass with respect to the total mass of the metal oxide particles and the binder material in the dispersion after removing the glass beads. In addition, silicone oil as a leveling agent (trade name: SH28PA, manufactured by Toray Dow Corning Co., Ltd.) is used so that the total mass of the metal oxide particles and the binder material in the dispersion is 0.01% by mass. A conductive layer coating solution was prepared by adding to the dispersion and stirring.
This conductive layer coating solution was dip-coated on the support, and the resulting coating film was dried and thermally cured at 150 ° C. for 30 minutes to form a conductive layer having a thickness of 30 μm.

Next, 15 parts of N-methoxymethylated 6-nylon resin (trade name: Toresin EF-30T, manufactured by Nagase ChemteX Corporation) and 5 parts of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) are added to methanol 220. An undercoat layer coating solution was prepared by dissolving in a mixed solvent of 1 part and 1 part butanol.
This undercoat layer coating solution is dip-coated on the conductive layer to form a coating film, and the resulting coating film is dried at a temperature of 100 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.65 μm. did.

  Next, 2 parts of polyvinyl butyral (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 100 parts of cyclohexanone. To this solution, 4 parts of a crystalline form of hydroxygallium phthalocyanine crystal (charge generation material) having strong peaks at 7.4 ° and 28.1 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction was added. . This was placed in a sand mill using glass beads having a diameter of 1 mm and dispersed for 1 hour in an atmosphere of 23 ± 3 ° C. After the dispersion treatment, 100 parts of ethyl acetate was added thereto to prepare a charge generation layer coating solution. This charge generation layer coating solution was dip-coated on the undercoat layer, and the resulting coating film was dried at 90 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.28 μm.

Next, 6 parts of the compound represented by the formula (CTM-7) (charge transport material) and 10 parts of the polyester resin (A) synthesized in Synthesis Example 1 are mixed into a mixed solution of 50 parts of tetrahydrofuran and 50 parts of cyclopentanone. Dissolved to prepare a coating solution for charge transport layer.
The charge transport layer coating solution is dip-coated on the charge generation layer to form a coating film, and the resulting coating film is dried at 130 ° C. for 30 minutes, whereby a charge transport layer (surface of 21 μm) (surface Layer).

  Thus, an electrophotographic photosensitive member having a support, a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer in this order was produced.

(Examples 2-33)
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that the polyester resin and the charge transport material were changed as shown in Table 2 in Example 1.

(Comparative Examples 1 to 13)
An electrophotographic photoreceptor was produced in the same manner as in Example 1 except that the polyester resin and the charge transport material were changed as shown in Table 2 in Example 1.

Next, evaluation of the produced electrophotographic photoreceptor will be described.
[Evaluation]
<Durability evaluation>
As an evaluation apparatus, a laser printer (trade name: Color LaserJet Enterprise M552, a modified machine manufactured by Hewlett Packard) (33 sheets per minute) was used. The evaluation was performed in a temperature 15 ° C. and humidity 10% RH environment. The image is output in an intermittent mode that stops once every time an image is output using A4 size plain paper. After outputting 10,000 images, the surface of the central portion of the electrophotographic photosensitive member from the initial stage is output. The amount of decrease in the thickness of the charge transport layer was evaluated. Film thickness measurement at that time is a film thickness measuring machine (trade name: Fisherscope MMS, manufactured by Fisher Instruments) equipped with an eddy current method probe (trade name: EAW3.3, manufactured by Fisher Instruments). I went there. The reduction amount of the film thickness of the charge transport layer is evaluated by a value obtained by converting the reduction amount of the film thickness after outputting 10,000 images per 1,000 sheets. The results are shown in Table 2.

<Evaluation of photomemory suppression effect>
Using the laser printer, the developing device of the black station of the evaluation machine was replaced with a potential measuring tool so that the surface potential of the electrophotographic photosensitive member at the developing position could be measured. A potential probe (trade name: MODEL6000B-8, manufactured by Trek Japan) is attached to the potential measurement tool, and the potential at the center of the electrophotographic photosensitive member in the direction of the bus is measured by a surface potential meter (trade name: MODEL344, Trek Japan). It was made possible to measure using The electrophotographic photosensitive member 1 was attached to the cartridge from which the cleaning blade was removed, and attached to the black station of the evaluation machine. The conditions of the charging device and the image exposure apparatus were adjusted so that the dark portion potential (VD) of the electrophotographic photosensitive member was −500 V and the light portion potential (VL) was −100 V in an environment of 23 ° C./50% RH.

  Samples for photomemory evaluation were prepared as follows. First, a black film for light shielding capable of covering the entire electrophotographic photosensitive member was prepared, and a rectangular hole having a size of 1.5 cm × 5 cm was formed in the film. This film was wrapped around an unused electrophotographic photosensitive member prepared for photomemory measurement, and the portions other than the holes were shielded from light. At this time, the 1.5 cm side of the hole is parallel to the circumferential direction of the electrophotographic photosensitive member so that the intersection of the diagonal lines of the hole is at the center of the electrophotographic photosensitive member in the bus line direction, and the side of 5 cm is the bus line. The position of the hole was adjusted to be parallel to the direction.

  Next, the position of the white fluorescent lamp (trade name: Paralite FPL-27EX-N, manufactured by Hitachi Lighting Co., Ltd.) was adjusted so that the exposure amount was 1500 lx on the surface of the electrophotographic photosensitive member. Then, the surface of the electrophotographic photosensitive member exposed from the hole portion was irradiated with the white light for 30 minutes. Here, a digital illuminometer (trade name: IM-3, manufactured by Topcon Corporation) was used to measure the exposure amount.

  Thereafter, the black film is removed, and 5 minutes after the end of the white light irradiation, the absolute value ΔVL (ΔVL = | VL2−VL1 | ) Was measured and the value was taken as the value of the photo memory. The results are shown in Table 2.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Guide means

Claims (9)

In an electrophotographic photoreceptor having a surface layer containing a charge transport material and a polyester resin,
The polyester resin has a structure represented by the general formula (I) and a structure represented by the general formula (II),

(In the general formula (I), X ¹ represents a divalent group.)

(In General Formula (II), X ² represents a single bond, an oxygen atom, a divalent substituted or unsubstituted methylene group, or a divalent substituted or unsubstituted cycloalkylidene group. R ^{11 to} R ¹⁸ are Each independently represents a hydrogen atom or an alkyl group.)
The structure represented by the general formula (I) includes a structure represented by the formula (I-1),

An electrophotographic photoreceptor, wherein the structure represented by the general formula (II) includes a structure represented by the general formula (II-1).

(In General Formula (II-1), at least 5 or more of R ^{21 to} R ²⁸ are alkyl groups, and the others are hydrogen atoms.)   2. The electrophotographic photosensitive member according to claim 1, wherein in the polyester resin, a ratio of the structure represented by the formula (I-1) in the structure represented by the general formula (I) is 30 mol% or more.   The electrophotographic photosensitive member according to claim 2, wherein in the polyester resin, a ratio of the structure represented by the formula (I-1) to the structure represented by the general formula (I) is 70 mol% or more.   4. The polyester resin according to claim 1, wherein a ratio of the structure represented by the general formula (II-1) in the structure represented by the general formula (II) is 30 mol% or more. 5. The electrophotographic photoreceptor described in 1.   5. The electrophotographic photosensitive member according to claim 4, wherein in the polyester resin, a proportion of the structure represented by the general formula (II-1) in the structure represented by the general formula (II) is 70 mol% or more. . The electrophotographic photosensitive member according to any one of claims 1 to 5, wherein in the polyester resin, the structure represented by the general formula (II-1) is further a structure represented by the formula (II-1-2). body.

The electrophotographic photosensitive member according to claim 1, wherein the charge transport material is a compound represented by the formula (A) or a compound represented by the formula (B).

  An electrophotographic photosensitive member according to any one of claims 1 to 7, 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; and a charging unit, an exposing unit, a developing unit, and a transferring unit.

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