JP2015141269A - Electrophotographic photoreceptor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having excellent wear resistance and stability of image characteristic, the photoreceptor being excellent in wear resistance, free of image blurring even in a hot and humid environment, excellent in dot reproducibility, and free of image memory.SOLUTION: The photoreceptor is an electrophotographic photoreceptor formed by laminating a photosensitive layer and a protective layer sequentially on a conductive support substance, wherein the protective layer contains a component obtained by polymerizing a p-type semiconductor particle (A) modified by a surface preparation agent having a polymerizable reactive group and a polymerizable compound and a p-type semiconductor particle (B) modified by a surface preparation agent not having a polymerizable reactive group, a number average primary particle diameter of the p-type semiconductor particle (A) being in the range 10 to 70 nm, a number average primary particle diameter of the p-type semiconductor particle (B) being in the range 100 to 300 nm.

Description

  The present invention relates to an electrophotographic photosensitive member and a method for producing the same, and more specifically, an electrophotographic photosensitive member having no dot blurring and improved dot reproducibility and image memory even in a high temperature and high humidity environment, and a method for producing the same. About.

  In recent years, organic photoreceptors containing organic photoconductive materials have been widely used as electrophotographic photoreceptors. Organic photoconductors are advantageous for inorganic photoconductors because it is easy to develop materials compatible with various exposure light sources from visible light to infrared light, the ability to select materials without environmental pollution, and low manufacturing costs. Is a point.

  On the other hand, an electrophotographic photoreceptor (hereinafter, also referred to as “photoreceptor”) is directly subjected to electrical or mechanical external force by charging, exposure, development, transfer, cleaning, etc., and therefore image formation is repeated. However, there is a demand for durability that can be stably maintained, such as charging stability and potential retention.

  In particular, in recent years, the demand for high-definition and high-quality images has increased in the trend of digitization, and toners having a small particle diameter by a polymerization method such as a dissolution suspension toner and an emulsion polymerization aggregation toner have become mainstream. These toners having a small particle diameter have a large adhesion force to the surface of the photoreceptor, and the removal of residual toner such as transfer residual toner attached to the surface of the photoreceptor is likely to be insufficient. In the cleaning method using a rubber blade, a phenomenon such as "toner slipping" where the toner passes through the blade, "blade curl" where the blade is reversed, or generation of scratching noise between the photosensitive member and the blade, so-called "blade squealing" occurs. Cheap. In order to solve the above-mentioned “toner slipping”, it is necessary to increase the contact pressure of the blade to the photosensitive member. However, the repeated use causes the surface of the organic photosensitive member to wear and the durability is insufficient. Will occur. Further, it is required to have sufficient durability against deterioration caused by ozone and nitrogen oxides generated during charging.

  For this reason, a technique for improving the mechanical strength by providing a protective layer (hereinafter also referred to as “surface layer”) on the surface of the photoreceptor has been proposed.

  Specifically, a polymerizable compound generally called a curable compound is used for the photoconductor protective layer, and after the coating, a curing reaction is performed, thereby being resistant to surface abrasion and scratches caused by friction of a cleaning blade or the like. A technique for producing a highly sensitive photoconductor has been proposed (see, for example, Patent Document 1 and Patent Document 2). In addition, a technique has been proposed in which inorganic fine particles such as silica are dispersed in a protective layer to improve mechanical strength (for example, see Patent Document 3).

  However, since the charge transport performance of the protective layer is inferior, the provision of the protective layer has a problem that the sensitivity characteristic as an electrophotographic photosensitive member is deteriorated as compared with an electrophotographic photosensitive member without a protective layer. . In order to solve this problem, it is possible to provide charge transport performance by including a charge transport material in the protective layer, but in general, the charge transport material of an organic compound has a plasticizing effect, so by adding a charge transport material, The strength of the protective layer is reduced. Therefore, a technique for obtaining a protective layer having a charge transport function in the protective layer and excellent in wear resistance is disclosed. For example, a technique for a protective layer in which a radical polymerizable compound having a charge transport function and a radical polymerizable compound not having a charge transport function and a filler modified with a surface treatment agent having a polymerizable functional group is subjected to a curing reaction is disclosed. (For example, refer to Patent Document 4). However, even with this technique, sufficient charge transport performance cannot be obtained, and the wear resistance is not satisfactory.

  Here, metal oxide particles such as silicon dioxide, aluminum oxide, and titanium dioxide are added as fillers, but these metal oxide particles can be expected to have a certain effect on improving wear resistance, but they are holes. The transport performance is not sufficient, and the image density difference due to the photoconductor cycle, that is, the so-called image memory is generated.

  Therefore, as a technique that satisfies both the wear resistance and charge transport performance of the protective layer, a technique of adding p-type semiconductor particles to the protective layer has been proposed (see, for example, Patent Document 5).

  However, although this technology has an effect of improving the image memory in a high temperature and high humidity environment, it is not always satisfactory under more severe conditions, and further in terms of image blur and dot reproducibility. Improvement was desired.

JP 11-288121 A JP 2009-69241 A JP 2002-333733 A JP 2010-164646 A JP 2013-130603 A

  The present invention has been made in view of the above-described problems and circumstances, and the solution to the problem is excellent wear resistance, no image blur even in a high temperature and high humidity environment, excellent dot reproducibility, and image memory. It is an object of the present invention to provide an electrophotographic photoreceptor excellent in wear resistance and image property stability and a method for producing the same.

  In order to solve the above-mentioned problems, the present inventor, in the course of studying the cause of the above-mentioned problems, p-type semiconductor particles modified with a surface treatment agent having a polymerizable reactive group in the protective layer of the electrophotographic photoreceptor (A ) And a polymerizable compound and a p-type semiconductor particle (B) modified with a surface treatment agent that does not have a polymerizable reactive group, and has excellent wear resistance. The present inventors have found that image characteristics such as image blur, dot reproducibility and image memory can be solved, and have reached the present invention.

  That is, the said subject which concerns on this invention is solved by the following means.

1. An electrophotographic photosensitive member obtained by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support,
The protective layer does not have a component obtained by polymerizing p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group and a polymerizable compound, and a polymerizable reactive group Containing p-type semiconductor particles (B) modified with a surface treatment agent,
The number average primary particle size of the p-type semiconductor particles (A) modified with the surface treatment agent having the polymerizable reactive group is in the range of 10 to 70 nm,
An electrophotographic photoreceptor, wherein the number average primary particle size of the p-type semiconductor particles (B) modified with the surface treating agent not having the polymerizable reactive group is in the range of 100 to 300 nm.

  2. P used for p-type semiconductor particles (A) modified with a surface treating agent having a polymerizable reactive group and p-type semiconductor particles (B) modified with a surface treating agent not having a polymerizable reactive group 2. The electrophotographic photosensitive member according to item 1, wherein the type semiconductor particles are a compound represented by the following general formula (1).

General formula (1): CuMO ₂
(In the formula, M represents an element belonging to Group 13 of the periodic table.)

  3. The addition amount of the p-type semiconductor particles (A) modified with the surface treating agent having a polymerizable reactive group is A part by mass, and the p-type semiconductor particles modified with the surface treating agent not having the polymerizable reactive group The addition amount ratio (A / B) is in the range of 6/4 to 9/1 when the addition amount of (B) is B parts by mass. Electrophotographic photoreceptor.

  4). The electrophotographic photosensitive member according to any one of Items 1 to 3, wherein the surface treatment agent having no polymerizable reactive group is a surface treatment agent having a fluorine atom.

  5. Item 5. The electrophotography according to any one of items 1 to 4, wherein the polymerizable compound is a polymerizable monomer having at least one of an acryloyl group and a methacryloyl group in a molecule. Photoconductor.

6). An electrophotographic photosensitive member manufacturing method for manufacturing the electrophotographic photosensitive member according to any one of items 1 to 5,
P-type semiconductor particles (A) modified with a surface treatment agent having at least a polymerizable reactive group, p-type semiconductor particles (B) modified with a polymerizable compound and a surface treatment agent not having a polymerizable reactive group (B ) Are mixed and dispersed in a solvent to prepare a coating solution for the protective layer, the coating solution is applied on at least a photosensitive layer provided on a conductive support, and a protective layer is formed. An electrophotographic photoreceptor comprising a step of reacting a p-type semiconductor particle (A) modified with a surface treatment agent having a polymerizable reactive group in a layer with a polymerizable compound by light or heat. Production method.

  By the above means of the present invention, excellent wear resistance, no image blur even in high temperature and high humidity environment, excellent dot reproducibility, no image memory, wear resistance and stability of image characteristics An electrophotographic photosensitive member excellent in the above and a method for producing the same can be provided.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  Generally, a charge transport material used in an electrophotographic photosensitive member is an organic compound and has an excellent hole transporting property, but also has a plasticizing effect. Therefore, an electrophotographic photosensitive member using an organic compound is used. The wear resistance of was not sufficient. On the other hand, a protective layer is provided on the photosensitive layer for the purpose of improving abrasion resistance, and metal oxide particles such as silicon oxide, aluminum oxide, and titanium oxide are added to the protective layer, and due to the filler effect of the metal oxide particles. Although attempts have also been made to improve wear resistance, these metal oxide particles do not provide sufficient hole transport capability, and charge (carriers) are trapped in the protective layer, resulting in image memory. It is considered a thing.

  For this reason, it was obtained by polymerizing p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group and a polymerizable compound in order to obtain a photoreceptor capable of achieving both wear resistance and image characteristics. By including the component in the protective layer, the effect of the high hardness of the p-type semiconductor particles, the polymerizable compound, and the polymerizable reactive group of the p-type semiconductor particles form a crosslinked structure, thereby providing abrasion resistance. Can be improved. Furthermore, since the p-type semiconductor particles have a hole transporting ability, the hole transporting ability of the protective layer is improved, and since charges are not trapped, an effect of improving the image memory can be obtained.

  In the present invention, by adding p-type semiconductor particles having a larger particle size, an appropriate surface roughness is imparted, the incorporation of the lubricant onto the surface of the photoreceptor becomes uniform, and the torque applied to the cleaning blade is reduced. it is conceivable that. If the lubricant is evenly taken in, it is easy to clean even if the discharge product adheres to the surface of the photoreceptor, so that an effect of improving image blur in a high temperature and high humidity environment can be obtained.

  On the other hand, the p-type semiconductor particles (A) modified with the surface treatment agent having a polymerizable reactive group polymerize with the polymerizable compound to form a crosslinked structure and are taken into the protective layer, resulting in a decrease in hole transport performance. It seems to do. Therefore, the hole transport performance can be maintained without impairing the strength of the protective layer by containing a small amount of the p-type semiconductor particles (B) modified with the surface treatment agent having no polymerizable reactive group. It is considered that the image blur and the image memory and the dot reproducibility can be improved.

Schematic diagram showing an example of the layer structure of the photoreceptor of the present invention Schematic of a cross section showing an example of an image forming apparatus using the photoreceptor of the present invention.

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member formed by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support, and the protective layer has a surface treatment having at least a polymerizable reactive group. Component obtained by polymerizing p-type semiconductor particles (A) modified with an agent and a polymerizable compound, and p-type semiconductor particles modified with a surface treatment agent having no polymerizable reactive group (B) And the number average primary particle size of the p-type semiconductor particles (A) modified with the surface treatment agent having the polymerizable reactive group is in the range of 10 to 70 nm and has the polymerizable reactive group. The number average primary particle size of the p-type semiconductor particles (B) modified with the surface treatment agent that is not used is in the range of 100 to 300 nm. This feature is a technical feature common to the inventions according to claims 1 to 6.

  Furthermore, it is used for the p-type semiconductor particles (A) modified with the surface treatment agent having a polymerizable reactive group and the p-type semiconductor particles (B) modified with a surface treatment agent not having the polymerizable reactive group. The p-type semiconductor particles to be obtained are preferably compounds represented by the following general formula (1). P used for p-type semiconductor particles (A) modified with a surface treating agent having a polymerizable reactive group and p-type semiconductor particles (B) modified with a surface treating agent not having a polymerizable reactive group When the type semiconductor particles are a compound represented by the following general formula (1), a high hole transport ability is obtained, and an image memory improving effect can be obtained.

General formula (1): CuMO ₂
(In the formula, M represents an element belonging to Group 13 of the periodic table.)
Further, the addition amount of the p-type semiconductor particles (A) modified with the surface treatment agent having a polymerizable reactive group is A part by mass, and the p-type modified with the surface treatment agent not having the polymerizable reactive group When the addition amount of the semiconductor particles (B) is B parts by mass, the addition amount ratio (A / B) is preferably in the range of 6/4 to 9/1. The addition amount of the p-type semiconductor particles (A) modified with the surface treating agent having a polymerizable reactive group is A part by mass, and the p-type semiconductor particles modified with the surface treating agent not having the polymerizable reactive group When the addition amount of (B) is B parts by mass, if the addition amount ratio (A / B) is within the above range, the effect of improving the image memory and improving the dot reproducibility can be obtained without impairing the film strength of the protective layer. can get.

  Moreover, it is preferable that the surface treating agent which does not have a polymerizable reactive group is a surface treating agent which has a fluorine atom. If the surface treatment agent having no polymerizable reactive group is a surface treatment agent having a fluorine atom, the releasability of the surface of the protective layer can be enhanced, and an effect of improving image blur can be obtained.

  Further, the polymerizable compound is preferably a polymerizable monomer having at least one of an acryloyl group or a methacryloyl group in the molecule. When the polymerizable compound is a polymerizable monomer having at least one of an acryloyl group or a methacryloyl group in the molecule, the wear resistance of the photoreceptor is improved and a highly durable photoreceptor can be obtained.

  In addition, the method for producing an electrophotographic photoreceptor of the present invention has at least p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group, a polymerizable compound, and a polymerizable reactive group. A step of preparing a coating solution for a protective layer by mixing and dispersing p-type semiconductor particles (B) modified with a non-surface treating agent in a solvent, and a photosensitive layer provided with the coating solution on at least a conductive support A process of forming a protective layer by coating on the p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group in the protective layer and the polymerizable compound are reacted by light or heat. And a process. This manufacturing method provides excellent wear resistance, no image blur even in high temperature and high humidity environments, excellent dot reproducibility, no image memory, and excellent wear resistance and stability of image characteristics. An electrophotographic photosensitive member can be obtained.

  Hereinafter, the constituent elements of the present invention, and modes and modes for carrying out the present invention will be described in detail. In the present application, “to” is used in the sense of including the numerical values described before and after the lower limit value and the upper limit value.

<< Electrophotographic Photosensitive Member of the Present Invention >>
The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member formed by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support, and the protective layer has a surface treatment having at least a polymerizable reactive group. Component obtained by polymerizing p-type semiconductor particles (A) modified with an agent and a polymerizable compound, and p-type semiconductor particles modified with a surface treatment agent having no polymerizable reactive group (B) And the number average primary particle size of the p-type semiconductor particles (A) modified with the surface treatment agent having the polymerizable reactive group is in the range of 10 to 70 nm and has the polymerizable reactive group. The number average primary particle size of the p-type semiconductor particles (B) modified with the surface treatment agent that is not used is in the range of 100 to 300 nm.

  Hereinafter, the structure of the protective layer according to the present invention will be described in detail, and the structure of the photoreceptor will be described later.

<Configuration of protective layer>
The protective layer according to the present invention is polymerized with “p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group” (hereinafter also referred to as “surface-modified p-type semiconductor particles (A)”). Components obtained by polymerizing a reactive compound and “p-type semiconductor particles (B) modified with a surface treatment agent having no polymerizable reactive group” (hereinafter referred to as “surface-modified p-type semiconductor particles (B)”) ")"). The number average primary particle size of the surface modified p-type semiconductor particles (A) is in the range of 10 to 70 nm, and the number average primary particle size of the surface modified p type semiconductor particles (B) is in the range of 100 to 300 nm. It is characterized by being within.

  The protective layer according to the present invention comprises a coating solution prepared by mixing and dispersing “surface-modified p-type semiconductor particles (A)”, “polymerizable compound” and “surface-modified p-type semiconductor particles (B)” in an organic solvent, The protective layer is formed by coating on the photosensitive layer and then polymerizing with light or heat.

<P-type semiconductor particles>
The surface-modified p-type semiconductor particles (A) used for the protective layer of the electrophotographic photoreceptor of the present invention and the p-type semiconductor particles used for the surface-modified p-type semiconductor particles (B) will be described.

  The p-type semiconductor particles used in the surface-modified p-type semiconductor particles (A) and the surface-modified p-type semiconductor particles (B) according to the present invention are semiconductor particles in which holes are used as carriers for transporting charges. It is. That is, it is a semiconductor in which holes are majority carriers.

  As the p-type semiconductor particles used in the present invention, a compound represented by the following general formula (1) is preferable.

General formula (1): CuMO ₂
(In the formula, M represents an element belonging to Group 13 of the periodic table.)
Specific examples of the Group 13 element include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). Group 13 elements preferably used in the present invention are aluminum, gallium, and indium. Preferred p-type semiconductor particles represented by the general formula (1) include, for example, CuAlO ₂ , CuGaO ₂ , and CuInO _2. It is done. By adding these p-type semiconductor particles to the protective layer of the electrophotographic photosensitive member, a high-quality electrophotographic photosensitive member having excellent abrasion resistance and no image memory can be obtained.

(Preparation method of p-type semiconductor particles)
The p-type semiconductor particles according to the present invention can be produced by the following method.
Al ₂ O ₃ (purity 99.9%) and Cu ₂ O (99.9%) were mixed at a molar ratio of 1: 1, calcined at a temperature of 1100 ° C. for 4 days in an Ar atmosphere, and then pelletized. And sintered at 1100 ° C. for 2 days to obtain a sintered body. Then, after coarsely pulverizing to several hundred μm, CuAlO ₂ having a desired particle diameter can be obtained by finely pulverizing the obtained coarse particles and a solvent using a wet media dispersion type apparatus.
As another method, for example, it can be generated by a plasma method. Examples of the plasma method include a direct current plasma arc method, a high frequency plasma method, and a plasma jet method.

  In the DC plasma arc method, a metal alloy is used as a consumption anode electrode. Then, a plasma flame is generated from the cathode electrode. Then, by heating and evaporating the metal alloy on the anode side and oxidizing and cooling the vapor of the metal alloy, p-type semiconductor particles can be obtained.

  The high frequency plasma method uses thermal plasma generated when a gas is heated by high frequency induction discharge under atmospheric pressure. Among these, in the plasma evaporation method, solid particles are injected into the center of the inert gas plasma, evaporated while passing through the plasma, and ultrafine particles can be generated by rapidly cooling and condensing the high-temperature vapor.

  In the plasma method, argon plasma, hydrogen plasma, etc. can be obtained by arc discharge in an inert gas argon and hydrogen or nitrogen or oxygen atmosphere which are diatomic molecular gases. In particular, diatomic molecular gas is thermally dissociated. The generated hydrogen (nitrogen, oxygen) plasma is extremely reactive as compared with molecular gas, so it is also called reactive arc plasma to distinguish it from inert gas plasma.

<Surface modified p-type semiconductor particles (A)>
The surface-modified p-type semiconductor particles (A) according to the present invention are obtained by surface-modifying the p-type semiconductor particles with a surface treatment agent having a polymerizable reactive group.

(Surface treatment agent having a polymerizable reactive group)
As the surface treatment agent having a polymerizable reactive group used for the surface-modified p-type semiconductor particles (A) according to the present invention, a surface treatment agent that reacts with a hydroxy group or the like present on the surface of the p-type semiconductor particles is preferable. Examples of the surface treatment agent include a silane coupling agent and a titanium coupling agent, and a surface treatment agent having a polymerizable reactive group is used for the purpose of further increasing the hardness of the protective layer. As the surface treatment agent having a polymerizable reactive group, a surface treatment agent having a radical polymerizable reactive group is preferable. These radical polymerizable reactive groups can also react with the polymerizable compound according to the present invention to form a strong protective film. As the surface treatment agent having a radical polymerizable reactive group, a silane coupling agent having a radical polymerizable reactive group such as a vinyl group, acryloyl group or methacryloyl group is preferable, and the surface treatment agent having such a radical polymerizable reactive group. Examples of such compounds include known compounds as described below.

_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl _{3
S-4: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
_{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
_{S-8: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) Cl 2
_{S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
S-11: CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19: CH 2 = C} (CH 3) COO (CH 2) 3 SiCl 3
_{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
_{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
_{S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
_{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
_{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
_{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2
Moreover, as a surface treating agent, you may use the silane compound which has the reactive organic group which can be radically polymerized other than said S-1 to S-36. These surface treatment agents can be used alone or in admixture of two or more.

<Surface modified p-type semiconductor particles (B)>
The surface-modified p-type semiconductor particles (B) used in the protective layer according to the present invention are obtained by surface-modifying p-type semiconductor particles with a surface treatment agent that does not have a polymerizable reactive group.

(Surface treatment agent not having a polymerizable reactive group)
As the surface treatment agent having no polymerizable reactive group used for the surface-modified p-type semiconductor particles (B) according to the present invention, a surface treatment that reacts with a hydroxy group or the like existing on the surface of the p-type semiconductor particles. Agents are preferred, and as these surface treatment agents, silane coupling agents, titanium coupling agents and the like are preferred. Examples of such a surface treatment agent include known compounds as described below.

_{S-37: CF 3 (CF} 2) 11 CH 2 CH 2 Si (OC 2 H 5) 3
_{S-38: CF 3 (CF} 2) 7 CH 2 CH 2 Si (OC 2 H 5) 3
_{S-39: CF 3 (CF} 2) 5 CH 2 CH 2 Si (OC 2 H 5) 3
_{S-40: CF 3 (CF} 2) 7 CH 2 CH 2 Si (OCH 3) 3
_{S-41: CF 3 (CF} 2) 3 CH 2 CH 2 Si (OC 2 H 5) 3
_{S-42: CF 3 (CF} 2) 5 CH 2 CH 2 Si (OCH 3) 3
_{S-43: CF 3 (CF} 2) 3 CH 2 CH 2 Si (OCH 3) 3
_{S-44: CF 3 (CF} 2) 3 CH 2 CH 2 Si (CH 3) 2 Cl
_{S-45: CF 3 (CF} 2) 4 CH 2 CH 2 Si (CH 3) 2 Cl
_{S-46: CF 3 (CF} 2) 5 CH 2 CH 2 Si (CH 3) 2 Cl
_{S-47: CF 3 (CF} 2) 3 CH 2 CH 2 SiCl 3
_{S-48: CF 3 (CF} 2) 5 CH 2 CH 2 SiCl 3
_{S-49: CF 3 CH 2} CH 2 SiCl 2 CH 3
S-50: CF ₃ CH ₂ CH ₂ SiCl _{3
S-51: CF 3 CH 2} CH 2 Si (OCH 3) 3
_{S-52: CH 3 CH 2} CH 2 Si (OCH 3) 3
_{S-53: CH 3 CH 2} CH 2 Si (OC 2 H 5) 3
_{S-54: CH 3 CH 2} CH 2 Si (OCH 3) 2 CH 3
_{S-55: CH 3 CH 2} CH 2 Si (CH 3) 2 OCH 3
_{S-56: C 5 H 11} Si (OC 2 H 5) 3
_{S-57: CH 3 (CH} 2) 4 CH 2 Si (OC 2 H 5) 3
_{S-58: CH 3 (CH} 2) 4 CH 2 Si (OCH 3) 3
_{S-59: CH 3 (CH} 2) 6 CH 2 Si (OC 2 H 5) 3
_{S-60: CH 3 (CH} 2) 6 CH 2 Si (OCH 3) 3
_{S-61: CH 3 (CH} 2) 6 CH 2 Si (CH 3) 2 OCH 3
_{S-62: CH 3 (CH} 2) 16 CH 2 Si (OCH 3) 3
_{S-63: CH 3 (CH} 2) 16 CH 2 Si (OCH 3) 2 CH 3
_{S-64: CH 3 (CH} 2) 16 CH 2 Si (CH 3) 2 OCH 3
_{S-65: CH 3 (CH} 2) 16 CH 2 Si (OC 2 H 5) 2 CH 3
Among the above surface treatment agents, a surface treatment agent having a fluorine atom is preferable.

(Number average primary particle size of surface-modified p-type semiconductor particles (A) and (B))
The number average primary particle size of the surface-modified p-type semiconductor particles (A) is in the range of 10 to 70 nm, and preferably in the range of 20 to 50 nm. If the number average primary particle size of the surface-modified p-type semiconductor particles (A) is less than 10 nm, the surface-modified p-type semiconductor particles (A) aggregate due to poor dispersibility in the protective layer coating solution, and a uniform coating film Can not form. On the other hand, when the thickness exceeds 70 nm, the film strength of the protective layer is reduced.

  The number average primary particle size of the surface-modified p-type semiconductor particles (B) is in the range of 100 to 300 nm, and preferably in the range of 100 to 200 nm. If the thickness is less than 100 nm, the effect of improving the surface roughness of the protective layer surface cannot be obtained. If the thickness exceeds 300 nm, the film density decreases, the protective layer becomes brittle, and the film strength decreases. Further, it is considered that the hole diameter is diffused and the dot reproducibility is deteriorated by increasing the particle diameter.

  When the addition amount of the surface-modified p-type semiconductor particles (A) is A parts by mass and the addition amount of the surface-modified p-type semiconductor particles (B) is B parts by mass, the addition ratio (A / B) is 6 It is preferable to be within the range of / 4 to 9/1, and within this range, the effect of improving the image blur and image memory and improving the dot reproducibility can be obtained without impairing the film strength of the protective layer.

(Method for measuring the number average primary particle size of the surface-modified p-type semiconductor particles (A) and (B))
The number average primary particle size of the surface-modified p-type semiconductor particles (A) and the surface-modified p-type semiconductor particles (B) is taken at 100,000 times with a scanning electron microscope (manufactured by JEOL), and randomly A photographic image (excluding aggregated particles) obtained by capturing 100 surface-modified p-type semiconductor particles with a scanner is an automatic image processing analyzer “LUZEX (registered trademark) AP” (manufactured by Nireco Corporation) software version Ver. 1.32 is used to binarize the surface-modified p-type semiconductor particles on the photographic image, calculate the horizontal ferret diameter for any 100 surface-modified p-type semiconductor particles, and calculate the average value thereof. The number average primary particle size is used. Here, the horizontal ferret diameter refers to the length of a side parallel to the x-axis of the circumscribed rectangle when the image of the surface-modified p-type semiconductor particles is binarized.

(Method for producing surface-modified p-type semiconductor particles (A) and surface-modified p-type semiconductor particles (B))
Production methods of p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group and p-type semiconductor particles (B) modified with a surface treatment agent not having a polymerizable reactive group are described below. As will be described, the surface modification method is the same except for the surface treatment agent used.

  When surface-modifying, it is preferable to treat using 100 wt parts of p-type semiconductor particles using a wet media dispersion type apparatus using 0.1 to 100 wt parts of the surface treatment agent and 50 to 5000 wt parts of the solvent. Moreover, it can also process by a dry type.

  Below, the surface modification method which manufactures the metal oxide particle surface-modified uniformly with the surface treating agent is demonstrated.

  That is, by subjecting a slurry (suspension of solid particles) containing p-type semiconductor particles and a surface treatment agent to wet pulverization, the p-type semiconductor particles are refined and simultaneously the surface modification of the particles proceeds. Thereafter, by removing the solvent and pulverizing, p-type semiconductor particles uniformly modified with the surface treatment agent can be obtained.

  The wet media dispersion type apparatus, which is a surface treatment apparatus used in the present invention, is filled with beads as a medium in a container and further rotated at high speed by a stirring disk attached perpendicularly to the rotation axis. It is an apparatus having a step of crushing and crushing / dispersing the aggregated particles, and the constitution thereof is that the p-type semiconductor particles are sufficiently dispersed and surface-modified when the surface modification is performed on the p-type semiconductor particles. For example, various types such as a vertical type, a horizontal type, a continuous type, and a batch type can be adopted without any problem. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersion-type devices are pulverized and dispersed by impact crushing, friction, shearing, shear stress, etc., using a grinding medium (media) such as balls and beads.

  As the beads used in the wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone and the like can be used, and those made of zirconia or zircon are particularly preferable. Further, as the size of the beads, those having a diameter of about 1 to 2 mm are usually used, but in the present invention, those having a diameter of about 0.1 to 1.0 mm are preferably used.

  Various materials such as stainless steel, nylon, and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

  By the wet treatment as described above, p-type semiconductor particles modified with the surface treatment agent can be obtained.

  In addition to these, the protective layer according to the present invention may be formed by containing a polymerization initiator, lubricant particles and the like as necessary.

  The total addition amount of the surface-modified p-type semiconductor particles (A) and (B) is preferably in the range of 50 to 300 parts by mass with respect to 100 parts by mass of the polymerizable compound described later.

≪Binder resin constituting protective layer≫
The protective layer contains a binder resin, and the binder resin is a component obtained by reacting a p-type semiconductor particle (A) modified with a surface treatment agent having a polymerizable reactive group and a polymerizable compound, That is, it contains a polymerization product in which a crosslinked structure is formed. In addition to this, a polymerization product in which only a polymerizable compound is polymerized, and a polymerization product in which p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group are polymerized are also included. A strong protective layer is formed by the polymerization product.

  As a binder resin usable in the protective layer according to the present invention, in addition to a product obtained by polymerizing a polymerizable compound, a known resin such as a polyester resin, a polycarbonate resin, a polyurethane resin, or a silicone resin is used in combination as a binder resin. You can also

(Polymerizable compound)
Examples of the polymerizable compound that can be used in the protective layer according to the present invention include a radical polymerizable compound, and the radical polymerizable compound has at least one of an acryloyl group and a methacryloyl group as a radical polymerizable reactive group. A polymerizable monomer is preferred.

  Examples of these polymerizable monomers include the following compounds, but the polymerizable monomers that can be used in the present invention are not limited thereto.

  The above radical polymerizable compounds are known and can be obtained as commercial products.

  Here, R represents the following acryloyl group, and R ′ represents the following methacryloyl group.

(Polymerization initiator)
As a method for polymerizing a polymerizable compound that can be used in the protective layer according to the present invention, a curing reaction is performed by a method using an electron beam cleavage reaction or a method using light or heat in the presence of a radical polymerization initiator. It can be carried out. When the curing reaction is performed using a radical polymerization initiator, any of a photopolymerization initiator and a thermal polymerization initiator can be used as the polymerization initiator. Further, both light and heat initiators can be used in combination.

  Examples of the polymerization initiator that can be used in the present invention include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), 2,2′-azobis (2 Azo compounds such as -methylbutyronitrile), benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, peroxide Examples thereof include thermal polymerization initiators such as peroxides such as lauroyl.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (Irgacure 369: manufactured by BASF Japan Ltd.), 2-hydroxy-2-methyl -1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Acetophenone or ketal photoinitiators, benzoin, benzoin methyl ether, Benzoin ether photopolymerization initiators such as inethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether Benzophenone photopolymerization initiators such as acrylated benzophenone and 1,4-benzoylbenzene, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone And thioxanthone-based photopolymerization initiators.

  Other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxide (Irgacure 819: manufactured by BASF Japan), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine And imidazole compounds. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.

  The polymerization initiator used in the present invention is preferably a photopolymerization initiator, preferably an alkylphenone compound or a phosphine oxide compound, more preferably an initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure. preferable.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-40 mass parts with respect to 100 mass parts of polymeric compounds, Preferably it is 0.5-20 mass parts.

(Lubricant particles)
It is also possible to contain various lubricant particles in the protective layer. For example, fluorine atom-containing resin particles can be added. Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

(solvent)
Solvents used for forming the protective layer include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, benzyl alcohol, methyl isopropyl ketone, and methyl isobutyl ketone. , Methyl ethyl ketone, cyclohexane, toluene, xylene, methylene chloride, ethyl acetate, butyl acetate, 2-methoxyethanol, 2-ethoxyethanol, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine and diethylamine. It is not limited to.

<Method for forming protective layer>
The electrophotographic photoreceptor of the present invention is produced by providing a protective layer on at least a photosensitive layer provided on a conductive support.

  The protective layer according to the present invention is modified with at least a p-type semiconductor particle (A) modified with a surface treatment agent having a polymerizable reactive group, a polymerizable compound, and a surface treatment agent not having a polymerizable reactive group. The p-type semiconductor particles (B) thus prepared are mixed and dispersed in a solvent to prepare a protective layer coating solution, and the coating solution is applied to at least a photosensitive layer provided on a conductive support for protection. A step of forming a layer and a step of polymerizing the protective layer with light or heat.

  The protective layer contains a polymerizable compound, surface-modified p-type semiconductor particles (A), surface-modified p-type semiconductor particles (B), and if necessary, known resins, polymerization initiators, lubricant particles, and antioxidants. The protective layer coating solution prepared in this manner can be applied to the surface of the photosensitive layer by a known method and reacted by actinic radiation or heat. The thickness of the protective layer is preferably 0.2 to 10 μm, and more preferably 0.5 to 6 μm.

  In the present invention, the polymerization reaction of the protective layer is carried out by irradiating the coating film with active rays to generate radicals and polymerizing, and forming a cross-linking bond by cross-linking reaction between molecules and within the molecule, and curing the cured resin. It is preferable to produce. The active ray is preferably light such as ultraviolet light or visible light, or an electron beam, and ultraviolet light is particularly preferred from the standpoint of ease of use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, an ultraviolet LED, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 1 to 20 mJ / cm ² , preferably 5 to 15 mJ / cm ² . The output voltage of the light source is preferably 0.1 to 5 kW, and particularly preferably 0.5 to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably in the range of 100 to 300 kV. The absorbed dose is preferably 0.005 Gy to 100 kGy (0.5 rad to 10 Mrad).

  The irradiation time of the active ray is a time for obtaining the necessary irradiation amount of the active ray, specifically 0.1 seconds to 10 minutes is preferable, and 1 second to 5 minutes is more preferable from the viewpoint of curing efficiency or work efficiency. It is said.

  In the present invention, the protective layer can be dried before and after irradiation with active rays and during irradiation with active rays, and the timing of drying can be appropriately selected in combination with the irradiation conditions of active rays. The drying conditions for the protective layer can be appropriately selected depending on the type of solvent used in the coating solution and the thickness of the protective layer. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 to 140 ° C. The drying time is preferably 1 to 200 minutes, particularly preferably 5 to 100 minutes. In the present invention, the amount of solvent contained in the protective layer can be controlled in the range of 20 ppm to 75 ppm by drying the protective layer under the above drying conditions.

<< Structure of photoconductor >>
<Layer structure of photoreceptor>
The photoreceptor of the present invention is obtained by forming a photosensitive layer and a protective layer on a conductive support. The layer structure of the photosensitive layer is not particularly limited, and examples of the specific layer structure of the photoreceptor of the present invention including the protective layer include the following.
(1) Layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated on a conductive support. (2) A single layer containing a charge transport material and a charge generation material on a conductive support. And a layer structure (3) in which a protective layer is sequentially laminated, and a layer structure (4) in which a middle layer, a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated on a conductive support. A layer structure in which an intermediate layer, a single layer containing a charge transport material and a charge generation material, and a protective layer are sequentially laminated. The photoreceptor of the present invention may have any one of the above-described layer structures (1) to (4). Among these, those having a layer structure prepared by sequentially providing an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer on a conductive support are particularly preferable.

  FIG. 1 is a schematic view showing an example of the layer structure of the photoreceptor of the present invention. In FIG. 1, 1 is a conductive support, 2 is a photosensitive layer, 3 is an intermediate layer, 4 is a charge generation layer, 5 is a charge transport layer, 6 is a protective layer, 7a is surface-modified p-type semiconductor particles (A), 7b shows surface-modified p-type semiconductor particles (B).

  Next, the conductive support, the intermediate layer, the photosensitive layer (charge generation layer, charge transport layer) and the member constituting the photosensitive layer constituting the photoreceptor of the present invention will be described.

<Conductive support>
The support used in the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or sheet, aluminum Metal foil such as copper or copper foil laminated on plastic film, aluminum, indium oxide, tin oxide, etc. deposited on plastic film, metal or plastic with conductive layer applied alone or with binder resin Examples include film and paper.

<Intermediate layer>
In the present invention, an intermediate layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. The intermediate layer can be formed by dip coating or the like by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent. Among the binder resins, an alcohol-soluble polyamide resin is preferable.

  The intermediate layer can contain various conductive fine particles and metal oxide particles for the purpose of adjusting the resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used. These metal oxide particles can be used alone or in combination. When two or more types are mixed and used, it may take the form of a solid solution or fusion. Such metal oxide particles preferably have a number average primary particle size of 0.3 μm or less, and more preferably 0.1 μm or less.

  As the solvent that can be used for forming the intermediate layer, a solvent in which inorganic fine particles such as conductive fine particles and metal oxide particles described above are well dispersed and a binder resin such as a polyamide resin is dissolved is preferable. Specifically, with respect to the polyamide resin, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like are preferable as the binder resin. It is preferable because good solubility and coating performance are exhibited. In order to improve the storage stability and the dispersibility of the inorganic fine particles, the following cosolvent can be used in combination with the solvent. Examples of the co-solvent that can provide a preferable effect include methanol, benzyl alcohol, toluene, cyclohexanone, tetrahydrofuran, and the like.

  The binder resin concentration at the time of forming the coating solution can be appropriately selected according to the film thickness of the intermediate layer and the coating method. Moreover, when inorganic fine particles etc. are disperse | distributed, it is preferable that the mixing ratio of the inorganic fine particles with respect to binder resin shall be 20-400 mass parts with respect to 100 mass parts of binder resin, and is 50-300 mass parts. It is more preferable.

  Examples of the means for dispersing the inorganic fine particles include, but are not limited to, an ultrasonic disperser, a ball mill, a sand grinder, and a homomixer.

  Moreover, the drying method of an intermediate | middle layer can select suitably a well-known drying method according to the kind of solvent and the film thickness to form, and heat drying is especially preferable.

  The thickness of the intermediate layer is preferably from 0.1 to 15 μm, more preferably from 0.3 to 10 μm.

<Photosensitive layer>
As described above, the photosensitive layer constituting the photoreceptor of the present invention has a charge generation layer (CGL) and a charge transport layer (CTL) in addition to a single layer structure in which a charge generation function and a charge transport function are provided in one layer. And a layer structure in which the functions of the photosensitive layer are separated from each other. As described above, the function-separated layer structure has a merit that it is easy to control various electrophotographic characteristics according to the purpose, in addition to being able to control the increase in residual potential with repeated use. The negatively chargeable photoreceptor has a structure in which a charge generation layer (CGL) is provided on an intermediate layer and a charge transport layer (CTL) is provided thereon. The positively chargeable photoreceptor is a charge transport layer (CTL) provided on the intermediate layer. The charge generation layer (CGL) is provided thereon. A preferred layer structure of the photosensitive layer is a negatively charged photoreceptor having the function separation structure.

  Below, each layer of the photosensitive layer of the function-separated negatively charged photosensitive member will be described as a specific example of the photosensitive layer.

(Charge generation layer)
The charge generation layer formed in the present invention contains a charge generation material and a binder resin, and is preferably formed by applying a coating solution in which the charge generation material is dispersed in a binder resin solution.

  Charge generation materials include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, phthalocyanine pigments, and the like. is not. These charge generating materials can be used alone or in a form dispersed in a known binder resin.

  As the binder resin for forming the charge generation layer, known resins can be used. For example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy Resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and copolymer resin containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resin) , Vinyl chloride-vinyl acetate-maleic anhydride copolymer resin) and poly-vinyl carbazole resin, but are not limited thereto.

  The charge generation layer is formed by dispersing the charge generation material in a solution obtained by dissolving the binder resin in a solvent using a disperser to prepare a coating solution, and applying the coating solution to a certain film thickness using a coating device. It is preferable to prepare the film by drying.

  Solvents for dissolving and coating the binder resin used in the charge generation layer include, for example, toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran , 1-dioxane, 1,3-dioxolane, pyridine, diethylamine and the like, but are not limited thereto.

  As a means for dispersing the charge generating material, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The mixing ratio of the charge generating material to the binder resin is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, and more preferably 0.05 to 3 μm. It should be noted that the coating solution for the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating. It can also be formed by vacuum deposition of the pigment.

(Charge transport layer)
The charge transport layer formed in the present invention contains at least a charge transport material and a binder resin in the layer, and is formed by dissolving and coating the charge transport material in a binder resin solution.

  A known compound can be used as the charge transport material, and examples thereof include the following. Carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benz Imidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene and poly-9 -Vinylanthracene and the like. These compounds can be used alone or in admixture of two or more.

  Moreover, well-known resin can be used for the binder resin for charge transport layers, for example, the following are mentioned. That is, polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic acid ester resin, styrene-methacrylic acid ester copolymer resin, and the like. Of these, polycarbonate resins are preferred, and polycarbonate resins of the types such as bisphenol A (BPA), bisphenol Z (BPZ), dimethyl BPA, and BPA-dimethyl BPA copolymer are crack resistant, wear resistant, and charging characteristics. From the point of view, it is preferable.

  The charge transport layer can be formed by a known method typified by a coating method. For example, in the coating method, a binder resin and a charge transport material are dissolved to prepare a coating solution, and the coating solution is formed into a certain film. A desired charge transport layer can be formed by drying after coating with a thickness.

  Examples of the solvent for dissolving the binder resin and the charge transport material include toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, 1,3- And dioxolane. The solvent used when preparing the coating liquid for forming the charge transport layer is not limited to the above.

  The mixing ratio of the binder resin and the charge transport material is preferably 10 to 500 parts by weight, and more preferably 20 to 100 parts by weight with respect to 100 parts by weight of the binder resin.

  The thickness of the charge transport layer varies depending on the characteristics of the charge transport material and the binder resin, the mixing ratio thereof, and the like, but is preferably 5 to 40 μm, and more preferably 10 to 30 μm.

  In the charge transport layer, a known antioxidant can be added. For example, an antioxidant described in JP-A-2000-305291 can be used.

<Coating method for each layer of photoreceptor>
Each layer such as an intermediate layer, a charge generation layer, a charge transport layer and a protective layer constituting the photoreceptor of the present invention can be formed by a known coating method. Specific examples include a dip coating method (dip coating method), a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, and a circular amount regulation type coating method (circular slide hopper coating method). It is done. In addition, the circular amount regulation type coating method is described in, for example, Japanese Patent Application Laid-Open Nos. 58-189061 and 2005-275373.

≪Image forming device≫
The image forming apparatus used in the present invention will be described.

  The electrophotographic image forming apparatus used in the present invention is an image forming apparatus using the photoreceptor of the present invention, and has at least a charging unit, an exposure unit, a developing unit, and a transfer unit. Further, the toner image transferred onto a transfer belt or the like is transferred onto a copy sheet, and a visible image can be obtained by fixing the toner image transferred onto the copy sheet onto the sheet with fixing means such as a contact heating method. it can.

  Note that a non-contact charging device is preferably used as the charging means for charging the electrophotographic photosensitive member. Examples of the non-contact charging device include a corona charging device, a corotron charging device, and a scorotron charging device.

  FIG. 2 is a schematic cross-sectional view illustrating an example of a color image forming apparatus showing one embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, a paper feeding and conveying means 21, and And fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y, an exposure unit (exposure step) 3Y, and a developing unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A unit (developing step) 4Y, a primary transfer roller 5Y as a primary transfer unit (primary transfer step), and a cleaning unit 6Y. The image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, and It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, a primary transfer roller 5C as a primary transfer unit, And cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk are centered around the photoreceptors 1Y, 1M, 1C, or 1Bk, and charging means 2Y, 2M, 2C, or 2Bk, exposure means 3Y, 3M, 3C, or 3Bk The developing means 4Y, 4M, 4C or 4Bk and the cleaning means 6Y, 6M, 6C or 6Bk for cleaning the photoreceptors 1Y, 1M, 1C or 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the color of the toner image to be formed on the photoreceptors 1Y, 1M, 1C, or 1Bk is different, and the image forming unit 10Y is taken as an example in detail. Explained.

  The image forming unit 10Y includes a charging unit 2Y, an exposing unit 3Y, a developing unit 4Y, and a cleaning unit 6Y around a photoconductor 1Y that is an image forming body, and a yellow (Y) toner image is placed on the photoconductor 1Y. To form. In the present embodiment, in the image forming unit 10Y, at least the photoreceptor 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photoreceptor 1Y. In the present embodiment, a corona discharge type charging unit 2Y is used as the photoreceptor 1Y.

  The exposure unit 3Y is a unit that performs exposure based on an image signal (yellow) on the photoreceptor 1Y to which a uniform potential is applied by the charging unit 2Y, and forms an electrostatic latent image corresponding to a yellow image. As the exposure means 3Y, an exposure element 3Y composed of LEDs and light-emitting elements arranged in an array in the axial direction of the photoreceptor 1Y and an imaging element (trade name; SELFOC (registered trademark) lens), or A laser optical system or the like is used.

  The developing unit 4Y includes, for example, a developing sleeve that contains a magnet and rotates while holding the developer, and a voltage applying device that applies a DC and AC bias voltage or a DC or AC bias voltage between the organic photosensitive member and the developing sleeve. It will be.

  The cleaning unit 6Y includes a cleaning blade and a brush roller provided on the upstream side of the cleaning blade.

  The image forming apparatus according to the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing unit and a cleaning unit as a process cartridge, and the image forming unit is configured to be detachable from the apparatus main body. You may do it. In addition, a process cartridge is formed by integrally supporting at least one of a charging unit, an exposure unit, a developing unit, a transfer or separation unit, and a cleaning unit together with a photosensitive member, and a single image forming unit that is detachable from the apparatus main body. Further, it may be configured to be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-shaped intermediate transfer body unit 7 has an endless belt-shaped intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  The fixing unit 24 is, for example, a heat roller fixing formed by a heating roller having a heating source therein and a pressure roller provided in pressure contact with the heating roller so as to form a fixing nip portion. One of the methods is mentioned.

  Each color image formed by the image forming units 10Y, 10M, 10C and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through the rollers 22A, 22B, 22C, 22D and the registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto the transfer material P, and the color images are collectively transferred. The transfer material P onto which the color image has been transferred is fixed by the fixing means 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a toner image transfer support formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk, and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, and 74, primary transfer rollers 5Y, 5M, 5C, and 5Bk, and a cleaning unit 6b. Become.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Preparation of surface modified particles>
As described below, “p-type semiconductor particles (A) and (B) modified with a surface treatment agent” and “surface-treated metal oxide particles” for comparison (hereinafter simply referred to as “surface modification”) according to the present invention. Particles ").

<Preparation of surface modified particles A>
(Preparation of surface modified particles A-1)
100 parts by mass of “CuAlO ₂ ” having a number average primary particle size of 20 nm as p-type semiconductor particles, 10 parts by mass of “3-methacryloxypropyltrimethoxysilane (S-15: manufactured by Gelest)” as a surface treatment agent, and 1000 parts by mass of methyl ethyl ketone Part is placed in a wet sand mill (alumina beads having a diameter of 0.5 mm), mixed at 30 ° C. for 6 hours, and then methyl ethyl ketone and alumina beads are separated by filtration and dried at 60 ° C. to obtain “surface modified particles A-1”. Prepared.

(Preparation of surface modified particles A-2)
In the production of the surface-modified particle A-1, “surface-modified particle A-2” is similar to the surface-modified particle A-1, except that “CuAlO ₂ ” having a number average primary particle size of 10 nm is used as the p-type semiconductor particle. Was made.

(Preparation of surface modified particles A-3)
In the production of the surface-modified particles A-1, “surface-modified particles A-3” were prepared in the same manner as the surface-modified particles A-1, except that “CuAlO ₂ ” having a number average primary particle size of 70 nm was used as the p-type semiconductor particles. Produced.

(Preparation of surface modified particles A-4)
In the production of the surface-modified particle A-1, “Surface-modified particle A-4” was produced in the same manner as in the surface-modified particle A-1, except that S-14 was used as the surface treatment agent.

(Preparation of surface modified particles A-5)
In the production of the surface-modified particle A-1, “Surface-modified particle A-5” was produced in the same manner as in the surface-modified particle A-1, except that S-31 was used as the surface treatment agent.

(Preparation of surface modified particles A-6)
In the production of the surface-modified particles A-1, “surface-modified particles A-6” were prepared in the same manner as the surface-modified particles A-1, except that “CuAlO ₂ ” having a number average primary particle size of 50 nm was used as the p-type semiconductor particles. Produced.

(Preparation of surface modified particles A-7)
In the production of the surface-modified particle A-1, “surface-modified particle A-7” was prepared in the same manner as the surface-modified particle A-1, except that “CuGaO ₂ ” having a number average primary particle size of 20 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles A-8)
In the production of the surface-modified particle A-1, “surface-modified particle A-8” was prepared in the same manner as the surface-modified particle A-1, except that “CuInO ₂ ” having a number average primary particle size of 20 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles A-9)
In the production of the surface-modified particle A-1, “surface-modified particle A-9” was prepared in the same manner as the surface-modified particle A-1, except that “CuAlO ₂ ” having a number average primary particle size of 5 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles A-10)
In the production of the surface-modified particle A-1, “surface-modified particle A-10” was prepared in the same manner as the surface-modified particle A-1, except that “CuAlO ₂ ” having a number average primary particle size of 100 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles A-11)
In the production of the surface-modified particle A-1, “Surface-modified particle A-11” was prepared in the same manner as the surface-modified particle A-1, except that S-52 having no polymerizable reactive group was used as the surface treatment agent. Produced.

(Preparation of surface modified particles A-12)
In the preparation of the surface-modified particle A-1, for comparison, the same as the surface-modified particle A-1, except that “SnO ₂ ” having a number average primary particle size of 20 nm was used as the metal oxide particle instead of the p-type semiconductor particle. Thus, “Surface modified particles A-12” were produced.

<Preparation of surface modified particles B>
(Preparation of surface modified particles B-1)
In the preparation of the surface-modified particle A-1, the same as the surface-modified particle A-1, except that “CuAlO ₂ ” having a number average primary particle size of 100 nm is used as the p-type semiconductor particle and S-51 is used as the surface treatment agent. Thus, “Surface-modified particle B-1” was produced.

(Preparation of surface modified particles B-2)
In the production of the surface modified particle B-1, “surface modified particle B-2” is the same as the surface modified particle B-1, except that “CuAlO ₂ ” having a number average primary particle size of 300 nm is used as the p-type semiconductor particle. Was made.

(Preparation of surface modified particles B-3)
In the production of the surface-modified particle B-1, “Surface-modified particle B-3” was produced in the same manner as the surface-modified particle B-1, except that S-43 was used as the surface treatment agent.

(Preparation of surface modified particles B-4)
In the production of the surface-modified particle B-1, “Surface-modified particle B-4” was produced in the same manner as the surface-modified particle B-1, except that S-52 was used as the surface treatment agent.

(Preparation of surface modified particles B-5)
In the production of the surface-modified particle B-1, “surface-modified particle B-5” was prepared in the same manner as the surface-modified particle B-1, except that “CuAlO ₂ ” having a number average primary particle size of 200 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles B-6)
In the preparation of the surface-modified particle B-1, “surface-modified particle B-6” was prepared in the same manner as the surface-modified particle B-1, except that “CuGaO ₂ ” having a number average primary particle size of 100 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles B-7)
In the production of the surface-modified particle B-1, “surface-modified particle B-7” was prepared in the same manner as the surface-modified particle B-1, except that “CuInO ₂ ” having a number average primary particle size of 100 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles B-8)
In the preparation of the surface-modified particle B-1, “surface-modified particle B-8” was prepared in the same manner as the surface-modified particle B-1, except that “CuAlO ₂ ” having a number average primary particle size of 70 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles B-9)
In the preparation of the surface-modified particle B-1, “surface-modified particle B-9” was prepared in the same manner as the surface-modified particle B-1, except that “CuAlO ₂ ” having a number average primary particle size of 350 nm was used as the p-type semiconductor particle. Produced.

(Preparation of surface modified particles B-10)
In the preparation of the surface-modified particle B-1, the same as the surface-modified particle B-1, except that “SiO ₂ ” having a number average primary particle size of 100 nm is used as the metal oxide particle instead of the p-type semiconductor particle for comparison. Thus, “Surface-modified particle B-10” was produced.

(Preparation of surface modified particles B-11)
In the production of the surface-modified particle B-1, “Surface-modified particle B-11” was produced in the same manner as the surface-modified particle B-1, except that S-15 having a polymerizable reactive group was used as the surface treating agent.

  Table 1 shows the structure of the surface-modified particles produced as described above.

<Preparation of Photoreceptor 1>
Photoreceptor 1 was produced as follows.

  The surface of a cylindrical aluminum support having a diameter of 60 mm was cut to prepare a conductive support.

<Intermediate layer>
A dispersion having the following composition was diluted 1.5 times with the same mixed solvent, allowed to stand overnight, and then filtered (filter; using a lysh mesh 5 μm filter manufactured by Nippon Pole Co., Ltd.) to prepare an intermediate layer coating solution.

Binder: Polyamide resin CM8000 (manufactured by Toray Industries, Inc.)
100 parts by mass Metal oxide particles: Titanium oxide SMT500SAS (manufactured by Teica)
120 parts by mass Metal oxide particles: Titanium oxide SMT150MK (manufactured by Teica)
155 parts by mass Solvent: ethanol / n-PrOH / THF (volume ratio 60/20/20)
1290 parts by mass Using a sand mill as a disperser, dispersion was performed in a batch mode for 5 hours.

  Using the coating solution, an intermediate layer was formed on the support by a dip coating method so as to have a dry film thickness of 2 μm.

<Charge generation layer>
Charge generation material: titanyl phthalocyanine pigment (titanyl phthalocyanine pigment having a maximum diffraction peak at a position of at least 27.3 ° as measured by Cu-Kα characteristic X-ray diffraction spectrum) 20 parts by mass Binder: polyvinyl butyral resin # 6000-C (electric (Made by Chemical Industries)
10 parts by mass Solvent: 700 parts by mass of t-butyl acetate 4-Methoxy-4-methyl-2-pentanone 300 parts by mass were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.

<Charge transport layer>
Charge transport material: 4,4′-dimethyl-4 ″-(β-phenylstyryl) triphenylamine 225 parts by mass Binder: Polycarbonate Z300 (manufactured by Mitsubishi Gas Chemical) 300 parts by mass Antioxidant: Irganox 1010 (manufactured by BASF Japan) ) 6 parts by mass Solvent: THF 1600 parts by mass Toluene 400 parts by mass Silicone oil: KF-54 (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass was mixed and dissolved to prepare a charge transport layer coating solution. A charge transport layer having a dry film thickness of 20 μm was formed on the charge generation layer by dip coating.

<Protective layer>
Surface-modified particle A-1 96 parts by mass Surface-modified particle B-1 24 parts by mass Binder: Polymerizable compound “Exemplary Compound M1” 100 parts by mass Polymerization initiator: Irgacure 819 (manufactured by BASF Japan) 6 parts by mass Solvent: 2 -Butanol 466 parts by mass Tetrahydrofuran 57 parts by mass The above components were mixed and stirred, and sufficiently dissolved and dispersed to prepare a protective layer coating solution. A protective layer was applied using a circular slide hopper applicator on the photoreceptor on which the coating solution had been prepared up to the charge transport layer. After the application, ultraviolet rays were irradiated for 1 minute using a xenon lamp, followed by drying at 80 ° C. for 70 minutes to obtain a protective layer having a dry film thickness of 3.0 μm. In this way, “Photoreceptor 1” was produced.

<Preparation of photoconductors 2-15>
The protective layer of the photoreceptor 1 was changed as shown in Table 2 and applied in the same manner. After the application, similarly, ultraviolet rays were irradiated for 1 minute and then dried at 80 ° C. for 70 minutes to obtain a protective layer having a dry film thickness of 3.0 μm. In this way, “Photosensitive members 2 to 15” were produced.

<Preparation of photoconductors 16 to 25>
Photoconductors 16 to 25 were prepared in the same manner except that the protective layer of the photoconductor 1 was changed as shown in Table 2. In addition, not the surface-modified p-type semiconductor particles (B) as large-diameter particles but also particles (surface-modified particles B-10) obtained by surface-modifying SiO ₂ as a metal oxide were added to the protective layer of the photoreceptor 22.

  In the photoreceptor 25, both the surface-modified p-type semiconductor particles (A) and (B) were p-type semiconductor particles modified with a surface treatment agent having a polymerizable reactive group as a surface treatment agent.

  Here, the photoconductors 1 to 15 are photoconductors of the present invention, and the photoconductors 16 to 25 are photoconductors of comparative examples.

[Evaluation of photoconductor]
The photoconductor 1 to photoconductor 25 produced as described above were evaluated as follows.

  As the evaluation machine, “Kizhub PRO C6501” manufactured by Konica Minolta Co., Ltd. basically having the configuration of FIG. 2 was used, and evaluation was performed by mounting each photoconductor on the evaluation machine.

  In a 23 ° C, 50% RH environment, a durability test was performed in which a character image with an image area ratio of 6% was printed on an A4 landscape feed with 300,000 double-sided prints for a total of 600,000 copies. The photoreceptor was evaluated for wear resistance, image memory, image blur and dot reproducibility. Evaluation was performed according to the following indicators.

[Evaluation of wear resistance]
The film thickness of the photosensitive layer was measured before and after the durability test, and the film thickness was calculated and evaluated.

  The film thickness of the photosensitive layer is measured at 10 points at random on the uniform film thickness part (excluding the film thickness fluctuation part at the leading and trailing edges of the coating), and the average value is measured for the photosensitive layer. The film thickness. The film thickness measuring device is an eddy current type film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GmbH), and the difference in the photosensitive layer thickness before and after the actual shooting test is used as the film thickness depletion amount. The amount of wear per 100 krot (100,000 revolutions) is shown in Table 3 as an α value. If the α value is within 0.2 μm, it can be said that the present invention satisfies a standard.

[Evaluation of image memory]
After the endurance test, ten images of solid black and solid white mixed are printed continuously, and then a uniform halftone image is printed, and the solid black and solid white history appears in the halftone image. Judgment is based on whether (memory is generated) or not (memory is not generated).

(Criteria)
A: No memory generated (good)
○: Minor memory is visible (no problem in practical use)
Δ: Memory is visible (problem is practical)
×: Clear memory is generated (practical problem)
[Evaluation of image blur]
After the durability test, a durability test (continuous feeding of A4 character images with environmental conditions of 30 ° C. and 80% RH and an image area ratio of 6%) was further added. Immediately after the additional durability test, the main power supply of the actual machine was stopped. Immediately after the stop, the power was turned on and the image was ready for printing. Immediately after that, a halftone image (relative reflection density of 0.4 with a Macbeth densitometer) and a 6-dot lattice image of the entire A3 were printed on the entire A3 neutral paper. The state of the printed image was observed and the following evaluation was performed.

(Criteria)
◎: No blurring in halftone and grid images (good)
○: A thin strip-like density decrease in the longitudinal direction of the photoreceptor is observed only in the halftone image (no problem in practical use)
Δ: Lattice image loss or line width narrowing due to image blurring occurs in some areas (practical problem)
×: Lattice image loss due to image blur or line width narrowing occurs entirely (practically problematic)
[Dot reproducibility]
After the endurance test, the internal mounting pattern no. 53 / Dot 1 (a typical exposure pattern formed in the form of dots having regularity) was printed at a density instruction value 100 by A3 / POD gloss coated paper (100 g / m ² ) manufactured by Oji Paper Co., Ltd. The formation state was visually observed and magnified.

(Criteria)
A: The dots are formed normally (good)
○: Some dots are thin (no problem in practical use)
Δ: The dots are thin overall (practical problem)
×: No dot formed (practical problem)

  As is apparent from the above results, the photoconductors 1 to 15 of the present invention have superior characteristics in image memory, image blur, and dot reproducibility compared with the photoconductors 16 to 25 of the comparative example. . On the other hand, the photoreceptors 16 to 25 of the comparative examples were inferior in any of the characteristics.

  Further, the photoconductor 16 of the comparative example has poor dispersibility of the surface-modified p-type semiconductor particles, cannot form a uniform protective layer, and cannot be used as a photoconductor.

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Photosensitive layer 3 Intermediate | middle layer 4 Charge generation layer 5 Charge transport layer 6 Protective layer 7a Surface modification p-type semiconductor particle (A)
7b Surface-modified p-type semiconductor particles (B)
1Y, 1M, 1C, 1Bk photoconductor 2Y, 2M, 2C, 2Bk charging means 3Y, 3M, 3C, 3Bk exposure means 4Y, 4M, 4C, 4Bk developing means 6Y, 6M, 6C, 6Bk cleaning means 10Y, 10M, 10C 10Bk image forming unit

Claims (6)

An electrophotographic photosensitive member obtained by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support,
The protective layer does not have a component obtained by polymerizing p-type semiconductor particles (A) modified with a surface treatment agent having a polymerizable reactive group and a polymerizable compound, and a polymerizable reactive group Containing p-type semiconductor particles (B) modified with a surface treatment agent,
The number average primary particle size of the p-type semiconductor particles (A) modified with the surface treatment agent having the polymerizable reactive group is in the range of 10 to 70 nm,
An electrophotographic photoreceptor, wherein the number average primary particle size of the p-type semiconductor particles (B) modified with the surface treating agent not having the polymerizable reactive group is in the range of 100 to 300 nm. P used for p-type semiconductor particles (A) modified with a surface treating agent having a polymerizable reactive group and p-type semiconductor particles (B) modified with a surface treating agent not having a polymerizable reactive group The electrophotographic photosensitive member according to claim 1, wherein the type semiconductor particles are a compound represented by the following general formula (1).
General formula (1): CuMO ₂
(In the formula, M represents an element belonging to Group 13 of the periodic table.)   The addition amount of the p-type semiconductor particles (A) modified with the surface treating agent having a polymerizable reactive group is A part by mass, and the p-type semiconductor particles modified with the surface treating agent not having the polymerizable reactive group The addition amount ratio (A / B) is in the range of 6/4 to 9/1 when the addition amount of (B) is B parts by mass. Electrophotographic photoreceptor.   The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the surface treatment agent having no polymerizable reactive group is a surface treatment agent having a fluorine atom.   5. The electrophotography according to claim 1, wherein the polymerizable compound is a polymerizable monomer having at least one of an acryloyl group and a methacryloyl group in a molecule. Photoconductor. An electrophotographic photosensitive member manufacturing method for manufacturing the electrophotographic photosensitive member according to any one of claims 1 to 5,
P-type semiconductor particles (A) modified with a surface treatment agent having at least a polymerizable reactive group, p-type semiconductor particles (B) modified with a polymerizable compound and a surface treatment agent not having a polymerizable reactive group (B ) Are mixed and dispersed in a solvent to prepare a coating solution for the protective layer, the coating solution is applied on at least a photosensitive layer provided on a conductive support, and a protective layer is formed. An electrophotographic photoreceptor comprising a step of reacting a p-type semiconductor particle (A) modified with a surface treatment agent having a polymerizable reactive group in a layer with a polymerizable compound by light or heat. Production method.

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