JPH10339962A - Electrophotographic photoreceptor, transfer layer-forming coating material and manufacture of this coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to stably maintaining electrostatic characteristics and further more enhancing toner releasability and surface property and mechanical resistance to printing. SOLUTION: This electrophotographic photoreceptor is formed by successively laminating a charge generating layer and a charge transfer layer on a conductive substrate, and this charge transfer layer contains vapor phase synthesized fine silica particles made hydrophobic with hexametlylenedisilazane and vapor phase synthesized fine silica particles made hydrophobic with an oligomer having a polydimethylsiloxane structure and these fine silica particles are uniformly dispersed into the transfer layer until the surface roughness becomes a center line average roughness of <=0.02 μm after finishing coating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoreceptor for electrophotography, a paint for forming a transport layer used for forming a charge transport layer, and a method for producing the paint for forming a transport layer.

[0002]

2. Description of the Related Art An electrophotographic apparatus is excellent in high-speed recording and low-noise properties, and has advantages such as being capable of recording with high image quality and recording on plain paper. Therefore, not only as a copying machine, but also as a printer and a facsimile, etc., it is becoming very popular. And
Especially in fields such as printers and facsimile machines,
Since the usage pattern is shifting from office use to personal use, further miniaturization and cost reduction, as well as maintenance-free, are required, and image processing that can obtain higher resolution and higher quality images There is a demand for the adoption of technology. Further, as a photoreceptor used in an electrophotographic apparatus, an organic photoreceptor having advantages such as easy film formation, low cost and no pollution, that is, an organic photoreceptor configured to contain an organic photoconductive material is used. In particular, organic photoconductors having high sensitivity in a long wavelength region suitable for laser beam printers and facsimile machines using a semiconductor laser as an exposure light source have been remarkably developed.

[0003] That is, most of organic photoreceptors that are put into practical use have a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance laminated on a conductive support in this order. The electrophotographic photoreceptor of this type comprises a thin-film charge generation layer formed on a conductive support (not shown). After forming a relatively thick charge transport layer on top,
A photosensitive layer is constituted by these two layers. In this case, the charge generation layer is a carrier.
The charge transport layer has a function of transporting carriers and a function of maintaining the charge potential of the photosensitive layer, and a function of maintaining the mechanical strength of the photosensitive layer. is there.

On the other hand, separately from such electrostatic characteristics, the charge transport layer located on the surface side of the photosensitive layer has excellent toner releasability, and furthermore, the wax component in the toner and the paper It is required to have excellent surface properties to prevent the components contained in the toner from adhering and sufficient mechanical printing durability. However, the electrophotographic photoreceptor is subjected to a charging step, an exposure step using image information, a developing step using toner, a transfer step, a cleaning step, and a charge removal step, and constitutes a photosensitive layer. If the toner release property or surface property of the charge transport layer is not sufficient, part of the toner remains in the transfer process, causing chipping or hollowing out of the image, or the wax component in the toner or the component contained in the paper. Adhesion may cause an undesired phenomenon called toner filming. In recent years, there has been a tendency to use toner having an increasingly finer particle size in order to achieve higher image quality, and there has been a demand for toner release properties in order to realize more efficient cleaning processes. It is growing.

Further, in a color image forming apparatus, which is increasing in recent years, a so-called color copying machine, a method of superimposing a plurality of color toners by transfer is adopted, and a developed image is faithfully transferred and superimposed as it is. Due to the necessity, it is strongly desired to realize an electrophotographic photoreceptor excellent in toner releasability. In addition, in order to prevent the occurrence of undesired surface adhesion phenomena such as toner filming, the use of the electrophotographic photoreceptor while scraping the charge transport layer little by little has been performed. In such a case, a sufficient life cannot be obtained, and excellent surface properties and sufficient mechanical printing durability cannot be obtained.

[0006] By the way, in order to meet the above demands, researches for improving the toner releasability and surface properties of the charge transporting layer are being actively conducted. For example, Japanese Patent Application Laid-Open No. Hei 7-261417 discloses the method. Is disclosed by incorporating gas-phase synthesized silica fine particles in the charge transport layer.
Japanese Patent Application Laid-Open No. 15877 discloses a technique for achieving high image quality while obtaining excellent toner releasability and surface properties by incorporating fluorine resin fine particles or silicone resin fine particles in a charge transport layer. In other words, it is practical to select a substance that easily develops properties suitable for the purpose from a variety of substances and then add it. Gas-phase synthetic silica particles that have been hydrophobized with dimethyldichlorosilane or hexamethylenedisilazane Alternatively, when gas-phase synthetic silica particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton are included in the charge transport layer, the toner releasability and surface properties are improved, and the mechanical printing durability is improved. A great effect is seen in improving the quality.

[0007]

However, when gas-phase synthetic silica fine particles are added to the charge transport layer, the chargeability and sensitivity are reduced, and in particular, charging and exposure are repeated. The stability of electrostatic properties such as chargeability, sensitivity, and residual potential will be greatly impaired when the method is executed, and stable use as an actual electrophotographic photoreceptor will be required. It will be difficult. Further, while it is possible to achieve a certain improvement in the toner releasability, surface properties, and mechanical printing durability, it is presently demanded to further improve these properties.

The inventors of the present invention included various gas-phase synthetic silica fine particles in the charge transport layer under various conditions and examined the influence on the electrostatic characteristics. The fact that the gas-phase synthesized silica fine particles themselves do not cause adverse effects on the electrostatic properties is due to the presence of aggregates of excessively aggregated gas-phase synthesized silica fine particles in the charge transport layer. Was. That is, the primary particle diameter of the gas-phase synthetic silica fine particles is generally several n.
m to several tens of nm, and it is inevitable that a certain amount of aggregates are naturally generated, but in a specific material system, it is excellent by suppressing the occurrence ratio of aggregates to a specific ratio or less. It became clear that the electrostatic characteristics could be stably maintained.

In addition, various kinds of gas-phase synthesized silica fine particles were incorporated into the charge transport layer under various conditions, and the effects of toner release properties, surface properties, and mechanical printing durability were examined. According to the findings, when the gas-phase synthetic silica particles hydrophobized using a specific substance are combined with each other and then included in the charge transport layer, a remarkable improvement effect is observed. Obtained.

The present invention has been made on the basis of these facts and knowledge, and can stably maintain electrostatic characteristics, and also has toner releasing properties, surface properties, and mechanical printing durability. It is intended to provide an electrophotographic photoreceptor, a coating material for forming a transport layer, and a method for producing the coating material, which are capable of realizing a further improvement in the above.

[0011]

According to a first aspect of the present invention, there is provided an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated on a conductive support in this order. The charge transport layer contains gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane and gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton. It is characterized in that the vapor-phase synthetic silica fine particles are uniformly dispersed until the surface roughness after the formation becomes 0.02 μm or less in center line average roughness. The charge transport layer constituting the electrophotographic photoreceptor according to claim 2 of the present invention is characterized in that it contains 4-N, N-diphenylamino-α-phenylstilbene as a charge transport material. .

The coating material for forming a transport layer according to claim 3 of the present invention is used for forming a charge transport layer of an electrophotographic photoreceptor, and comprises hexamethylene disilazane together with a charge transport material and a binder resin. , And gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton dissolved in toluene.
The charge transport material of the coating material for forming a transport layer according to claim 4 of the present invention is to be 4-N, N-diphenylamino-α-phenylstilbene.

According to a fifth aspect of the present invention, there is provided a method for producing a coating for forming a transport layer, which is used for forming a charge transport layer of an electrophotographic photoreceptor.
The gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane and the gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton are mixed with beads and dispersed in toluene. Wherein the charge transport material and the binder resin are dissolved in the dispersed liquid. The method for producing a coating material for forming a transport layer according to claim 6 of the present invention is characterized in that the beads mixed with the gas-phase synthetic silica fine particles have a diameter of 3 mm or less and a specific gravity of 4 or more.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although not shown in the drawings, an electrophotographic photoreceptor, a paint for forming a transport layer, and a method for producing the paint according to an embodiment of the present invention will be described below.

The electrophotographic photosensitive member according to the present embodiment is
A thin-film charge generation layer is formed on the conductive support, and
A relatively thick charge transport layer is formed on the charge generation layer, and the charge generation layer and the charge transport layer constitute a photosensitive layer. When necessary, an intermediate layer, an adhesive layer, a blocking layer, and the like are provided between the charge generation layer and the charge transport layer, or between the charge generation layer and the conductive support. . And the conductive support provided in the electrophotographic photoreceptor is a substrate manufactured using a conductive material known per se, for example,
Substrate made of metal material such as aluminum or conductive plastic (conductive particles such as carbon dispersed in insulating resin such as phenolic resin), or aluminum iodide, copper iodide, chromium oxide Or a substrate made of glass or the like coated with a conductive substance such as tin oxide, and the substrate has a shape such as a drum shape (pipe shape), a plate shape, or a belt shape, that is, particularly limited. It has a shape that is not performed.

In this case, the charge generation layer is a thin film formed by laminating on a conductive support after containing a conventionally well-known charge generating substance. Of oxotitanium phthalocyanine vapor-deposited with an organic solvent, or a pigment prepared in advance as a crystal having excellent photoelectric conversion ability and dispersed in a binder resin. The thickness of the charge-generating layer may vary depending on the type and state of the charge-generating substance.
The range is from nm to 1000 nm, preferably about 50 nm to 150 nm.

Further, the charge transport layer formed by laminating on the charge generation layer is composed of vapor-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane and air-hydrophobized hydrophobic particles with an oligomer having a polydimethylsiloxane skeleton. And phase-synthetic silica fine particles, and the surface roughness after coating and forming is not more than 0.02 μm in center line average roughness, and the thickness of this charge transport layer is from several μm to several tens μm. , Preferably about 15 μm to 30 μm.
Note that the surface roughness of 0.02 μm or less in terms of the center line average roughness indicates the degree to which the above two kinds of vapor-phase synthetic silica fine particles are sufficiently and uniformly dispersed in the charge transport layer. In the charge transport layer provided in the electrophotographic photoreceptor according to the embodiment, the two kinds of gas-phase synthetic silica fine particles are sufficient until the surface roughness is 0.02 μm or less in center line average roughness. It means that they are uniformly dispersed.

Further, the charge transport layer is formed so as to also contain 4-N, N-diphenylamino-α-phenylstilbene which is a charge transport material, and the charge transport layer is formed by a dip coating method. The transport layer forming paint applied on the charge generating layer is dried by using a well-known coating method such as coating, ring coating, blade coating, spray coating, or the like. That is, the coating material for forming a transport layer is composed of gas-phase synthetic silica particles hydrophobized with hexamethylene disilazane and gas-phase synthetic silica hydrophobized with an oligomer having a polydimethylsiloxane skeleton, together with a charge transport material and a binder resin. Fine particles are dissolved in toluene, which is a solvent for coating, and 4-N, N-diphenylamino-α-phenylstilbene is used as a charge transport material.

In this case, in the paint for forming the transport layer, the addition ratio of the gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane is 0.1% by weight based on the total solid content in the paint. To 30%, preferably 0.
The addition ratio of the gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton is from 0.1% to 30% by weight based on the total solid content in the coating material. Within the range, preferably 0.
It is about 5% to 10%. Further, the solvent for forming the coating material is not limited to toluene alone, and of course, other solvents may be mixed in order to achieve the purpose of adjusting the viscosity and the drying speed. Further, the paint-forming solvent is used so that the total solid content of the paint is 5% to 70% by weight. In this case, an appropriate viscosity is obtained depending on the binder resin and the coating method. Adjustments have been made to make it so.

Various charge transporting substances can be used, such as heterocyclic compounds such as oxazole, oxadiazole, and pyrazoline; hydrazone compounds, butadiene compounds, stilbene compounds, and various derivatives of these compounds. And the like can be cited as usable examples. However, when 4-N, N-diphenylamino-α-phenylstilbene is used as the charge transporting material, it is possible to secure better electrostatic characteristics and mechanical printing durability than other materials. Further, examples of the binder resin in this case include polyester, polycarbonate, polysulfone, and polymethyl methacrylate. The compounding ratio of the charge transport material and the binder resin is in a range of 1: 2 to 2: 1 by weight. Have been. If the proportions of these components are too small, the electrostatic properties deteriorate, and if the proportions are too large, the mechanical printing durability deteriorates.

Next, a method for producing a coating material for forming a transport layer used in forming a charge transport layer of an electrophotographic photosensitive member will be described. First, the coating material for forming a transport layer according to the present embodiment, together with a charge transport material of 4-N, N-diphenylamino-α-phenylstilbene and a binder resin,
Gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane and gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton are dissolved in toluene as a paint-forming solvent. When producing such a coating material for forming a transport layer, gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane and gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton are mixed with toluene. After performing the dispersion in the liquid, the charge transport material and the binder resin are dissolved in the obtained dispersion. As a specific method for dispersing the above two kinds of vapor-phase synthetic silica fine particles, after putting these vapor-phase synthetic silica fine particles and toluene in a predetermined container prepared in advance, zirconia or the like is used. A method of shaking and rotating after putting a predetermined amount of beads (media) consisting of into the container, so-called shaking method is adopted, and when the gas phase synthetic silica fine particles are sufficiently and uniformly dispersed Can create a state in which the vapor-phase synthesized silica fine particles are hardly aggregated.

By the way, in order to create a state in which the vapor-phase synthesized silica particles are hardly aggregated, it is important to use heavy beads having a small external shape when performing the operation of dispersing the gas-phase synthesized silica particles. According to the study of the inventors of the present invention, it has been confirmed that it is desirable to use beads having a diameter of 8 mm or less and a specific gravity of 2 or more, most preferably beads having a diameter of 3 mm or less and a specific gravity of 4 or more. I have. That is, in this case, the method for producing the coating material for forming a transport layer includes a vapor-phase synthetic silica fine particle hydrophobized with hexamethylene disilazane and a gas-phase synthetic silica fine particle hydrophobized with an oligomer having a polydimethylsiloxane skeleton. After mixing with beads having a diameter of 3 mm or less and a specific gravity of 4 or more and dispersing in toluene, the charge transport material and the binder resin are dissolved in the obtained dispersion. The method for dispersing the gas-phase synthetic silica fine particles is not limited to the shaking method that is usually adopted, but is a continuous method in which the gas-phase synthetic silica fine particles and toluene are dispersed while being poured into beads which are arranged to a certain extent. Of course, other methods such as a processing method may be adopted.

[0023]

EXAMPLES Hereinafter, specific examples and comparative examples of the present embodiment will be described.

(Example 1) First, a cylindrical aluminum cutting tube (A40S manufactured by Kobe Steel Co., Ltd.) having an outer diameter of 30 mm, a length of 301.5 mm, and a surface roughness of 1 s was placed on a conductive support. After that, the aluminum cutting tube was immersed in acetone and subjected to ultrasonic cleaning. Then, a conductive support, which is an aluminum cutting tube subjected to ultrasonic cleaning, is placed in a vacuum chamber, and the inside of the vacuum chamber is reduced to about 1 Pa by vacuum evacuation using a mechanical booster pump and a rotary pump. After evacuation, the oxygen flow rate was set to 200 sccm and the pressure was set to 50 sccm.
Pa and the distance between the conductive support and the center is 5
A power of 50 W is applied for 10 minutes from a high-frequency power supply of 500 kHz to an aluminum glow discharge electrode having a diameter of 8 mm disposed opposite to a parallel position of 0 mm for 10 minutes, and an oxygen glow discharge plasma is generated near the surface of the conductive support. The formation process of the aluminum oxide film was performed by forming. The thickness of the aluminum oxide film layer thus obtained was about 4 nm.

Next, the inside of the vacuum chamber is evacuated to about 5 × 10 ⁻³ Pa using a diffusion pump equipped with a cold trap, and the oxo-titanium previously placed on a molybdenum evaporation boat is used. The phthalocyanine was evaporated while being heated by energizing the evaporation boat, and an oxotitanium phthalocyanine evaporated film having a thickness of about 0.1 μm was formed on the surface of the conductive support. Further, the oxotitanium phthalocyanine vapor-deposited film thus formed was allowed to stand in a mixed saturated vapor composed of chlorobenzene and water at room temperature for 30 minutes to perform a crystal conversion, thereby obtaining a charge generation layer.

On the other hand, gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane (manufactured by Cabot Corporation,
1 part by weight of trade name Kyobosil TS530) and 1 part by weight of vapor-phase synthetic silica fine particles (Kybosil TS720, trade name, manufactured by Cabot Corporation) hydrophobized with an oligomer having a polydimethylsiloxane skeleton and a specific gravity of 1 mm in diameter And 4,500 parts by weight of zirconia beads, and 270 parts by weight of toluene were mixed in a predetermined container prepared in advance, and then mixed with a paint conditioner (manufactured by Imex Corporation, The product was shaken continuously for 10 hours with each container after using Red Devil (trade name). Subsequently, when the zirconia beads were removed from the dispersion solution produced by continuing to shake, the gas-phase synthetic silica particles hydrophobized with hexamethylene disilazane and the gas-phase synthetic silica hydrophobized with an oligomer having a polydimethylsiloxane skeleton were obtained. This means that a toluene dispersion obtained by dissolving the fine particles in toluene was obtained.

Further, with respect to 54 parts by weight of the obtained toluene dispersion, 10 parts by weight of 4-N, N-diphenylamino-α-phenylstilbene (manufactured by Nippon Steel Chemical Co., Ltd.) and a polycarbonate resin (Mitsubishi Gas Chemical) After manufacturing a transport layer forming paint by dissolving 10 parts by weight of Industrial Co., Ltd., trade name Iupilon Z-300),
The obtained transport layer forming paint is dip-coated on the previously formed charge generation layer, and then subjected to a hot-air drying treatment at 105 ° C. for 35 minutes to obtain a dried film thickness of 20 μm. A photosensitive layer was formed by forming a charge transport layer, and an electrophotographic photosensitive member was completed. Thereafter, the initial electrostatic characteristics of the completed electrophotographic photoreceptor and the electrostatic characteristics after 1000 times of use, that is, the charging potential,
The photoreceptor drum electrostatic characteristics evaluation apparatus (trade name: CYNTHIA, manufactured by Gentec Co., Ltd.)
55. SN), the results shown in Table 1 were obtained.

That is, in this evaluation test, the charging potential when the electrophotographic photosensitive member was negatively charged in a dark place by DC corona discharge set so that the corona current was -30 μA was V0 (V), 2 DDR2 dark retention rate for 2 seconds
(%), A monochromatic light having a maximum peak wavelength of 800 nm is used as a light source.
The energy required to attenuate the surface potential by half at the time of continuous irradiation with an intensity of 9 μW / cm ² is E
1/2 (μJ / cm ² ), irradiation energy is 3 μJ / cm ²
Is set to VR (V), an LED having a wavelength of 600 nm is used as static elimination light, and the energy is 20 μJ / cm ² . Further, the center line average roughness Ra for evaluating the surface roughness of the charge transport layer is Ra.
(μm), the dynamic friction coefficient μ against steel balls for evaluating the surface properties and the pure water contact angle θ (deg.), and the amount of wear for evaluating the mechanical printing durability, that is, mounted on a commercially available printer Then, after printing 100K sheets, the wear amount (μm) measured by a film thickness meter was evaluated, and the results shown in Table 1 were obtained. In addition, an electrophotographic photoreceptor is mounted on the image forming apparatus from the normal charging process to the static elimination process, and it is evaluated whether or not images are missing, hollow, or fogged in the transfer process. As a result, the results shown in Table 1 were obtained.

[0029]

[Table 1]

(Example 2) In Example 2, 1,1-bis (p-diethylaminophenyl) -4 was replaced with 10 parts by weight of 4-N, N-diphenylamino-α-phenylstilbene in Example 1. , 4-diphenyl-1,3-butadiene (T-405 manufactured by Annan Co., Ltd.) is used. Then, a paint for forming a transport layer was prepared according to the same procedure as in Example 1, and an electrophotographic photoreceptor was completed by using the prepared paint for forming a transport layer. When the test was performed, the results shown in Table 1 were obtained.

Comparative Example 1 In Example 1, gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane (Kyobosil TS530, manufactured by Cabot Corp.)
By using 1 part by weight and 1 part by weight of gas-phase synthetic silica fine particles (manufactured by Cabot Corp., trade name Kyobosil TS720) hydrophobized with an oligomer having a polydimethylsiloxane skeleton, a paint for forming a transport layer was prepared. On the other hand, in Comparative Example 1, only 1 part by weight of gas-phase synthetic silica fine particles (Kyobosil TS530, manufactured by Cabot Corporation) hydrophobicized with hexamethylene disilazane was used. The electrophotographic photoreceptor was completed by the same procedure as in Example 1, and the same evaluation test was performed. The results shown in Table 1 were obtained.

Comparative Example 2 In Comparative Example 2, only 1 part by weight of gas-phase synthetic silica fine particles (Kyobosil TS720, manufactured by Cabot Corporation) hydrophobized with an oligomer having a polydimethylsiloxane skeleton was used. The use of the two kinds of gas phase synthetic silica fine particles in Example 1 has been carried out. Then, when an evaluation test was performed after the electrophotographic photosensitive member was completed, the results shown in Table 1 were obtained.

(Comparative Example 3) In Example 1, the diameter was 1 m.
Comparative Example 3 in which zirconia beads of m were used and gas-phase synthesized silica particles were mixed.
Uses glass beads having a diameter of 6 mm and mixes gas-phase synthetic silica fine particles under the same other conditions. Then, a coating material for forming a transport layer was prepared in the same procedure as in Example 1, and a completed evaluation of an electrophotographic photoreceptor was performed using the prepared coating material for forming a transport layer. When I went,
The results as shown in Table 1 were obtained.

(Comparative Example 4) The coating material for forming the transport layer in each of the above Examples and Comparative Examples contained fine particles of vapor-phase synthetic silica. It does not contain synthetic silica fine particles. After completing the electrophotographic photoreceptor according to the same procedure as in Example 1, the same evaluation test was performed. The results shown in Table 1 were obtained.

According to the results of the evaluation test shown in Table 1, the charge transporting layers according to the examples have excellent surface properties and mechanical printing durability, as well as excellent electrostatic properties, as compared with the comparative examples. It is clear that That is, the initial electrostatic properties of the charge transport layer according to the example are excellent in chargeability,
It shows a sufficiently high dark retention and sensitivity, and a sufficiently low residual potential. Also,
No fogging or noise has occurred in the image, and an image of good quality without any chipping or voids in the transfer process has been obtained. In addition, even after the process from charging to static elimination is continuously repeated, excellent chargeability, high dark retention and sensitivity, and sufficiently low residual potential are ensured, and charge transport with excellent repetition stability. It can be seen that the electrophotographic photoreceptor has a layer.

Further, 4-N, N-
It is also clear that high mechanical printing durability can be obtained when diphenylamino-α-phenylstilbene is used,
When both the gas-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane and the gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton were simultaneously dispersed, better results were obtained. It has also been confirmed that excellent surface properties and high mechanical printing durability can be obtained. Further, when two kinds of vapor-phase synthetic silica fine particles are sufficiently and uniformly dispersed, and the surface roughness of the charge transport layer is 0.02 μm or less in center line average roughness, the charging is stopped. Even after repeating the static elimination process,
It has been clarified that excellent chargeability, sufficiently high dark retention and sensitivity are ensured, and a sufficiently low residual potential can be obtained.

[0037]

As is apparent from the above description, according to the electrophotographic photoreceptor, the paint for forming the transport layer and the method for producing the paint according to the present invention, it is possible to stably maintain the electrostatic characteristics. As a result, it is possible to obtain the effect that the toner releasability, surface properties, and mechanical printing durability can be further improved. Accordingly, not only are the electrostatic properties such as chargeability, dark retention, sensitivity, and residual potential excellent, but also little change in the properties due to repeated use is obtained, and the toner is excellent in toner releasability and surface properties. Thus, it is possible to provide an electrophotographic photoreceptor capable of stably obtaining an extremely high-quality image without chipping, hollowing, fogging, or the like.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tsumugi Oto 1006 Kazuma Kazuma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. An electrophotographic photoconductor comprising at least a charge generation layer and a charge transport layer laminated in this order on a conductive support, wherein the charge transport layer is hydrophobized with hexamethylene disilazane. And the vapor-phase synthesized silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton, and the surface roughness after coating is 0.1% in center line average roughness. A photoreceptor for electrophotography, wherein fine particles of vapor-phase synthetic silica are uniformly dispersed until the particle diameter becomes equal to or less than 02 μm. 2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer contains 4-N, N-diphenylamino-α-phenylstilbene as a charge transport substance. A photoconductor for electrophotography, characterized by: 3. A paint for forming a transport layer used for forming a charge transport layer of a photoreceptor for electrophotography, wherein the paint for forming a transport layer comprises hexamethylenediamine together with a charge transport material and a binder resin. A coating material for forming a transport layer, which is obtained by dissolving gas-phase synthetic silica particles hydrophobized with silazane and gas-phase synthetic silica particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton in toluene. . 4. The coating material for forming a transport layer according to claim 3, wherein the charge transport material is 4-N, N-diphenylamino-α-.
A paint for forming a transport layer, which is phenylstilbene. 5. A method for producing a coating material for forming a transport layer used for forming a charge transport layer of a photoreceptor for electrophotography, comprising: vapor-phase synthetic silica fine particles hydrophobized with hexamethylene disilazane; After mixing gas-phase synthetic silica fine particles hydrophobized with an oligomer having a polydimethylsiloxane skeleton together with beads and dispersing them in toluene, the charge transport material and the binder resin are dissolved in the obtained dispersion. A method for producing a paint for forming a transport layer, the method comprising: 6. The method for producing a paint for forming a transport layer according to claim 5, wherein the beads have a diameter of 3 mm or less and a specific gravity of 4 or more. .