JP2012247474A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in wear resistance, generating no density difference by cycles of the photoreceptor and achieving both of wear resistance and stability in image characteristics.SOLUTION: An electrophotographic photoreceptor includes at least a photosensitive layer and a protective layer successively layered on a conductive support. The protective layer contains a reaction product of a radical polymerizable compound and metal oxide fine particles. A solvent used for coating the protective layer is at least one kind selected from alcohols and ketones. The total amount of the solvent included in the protective layer is 20 ppm or more and 75 ppm or less.

Description

  The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor used in an image forming apparatus using an electrophotographic system.

  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 photosensitive member (hereinafter also referred to as a photosensitive member) is directly charged with electrical or mechanical external force by charging, exposure, development, transfer, cleaning, etc., so that charging is stable even when image formation is repeated. The durability which maintains stably, such as a property and electric potential retention property is calculated | required.

  In recent years, especially in the digital trend, demand for high-definition and high-quality images has increased, and toners with small particle diameters by polymerization methods such as dissolved suspension toners and emulsion polymerization aggregation toners have become mainstream. The toner having a small particle size has a large adhesion force to the surface of the photoconductor, and the removal of residual toner such as transfer residual toner adhering to the surface of the photoconductor tends to be insufficient. In the cleaning method using a rubber blade, there are phenomena such as "toner slipping" where the toner passes through the blade, "blade curl" where the blade is reversed, or the generation of scratching noise between the photoconductor and the blade, so-called "blade squealing" Likely to happen. In order to solve the above “toner slipping”, it is necessary to increase the contact pressure of the blade to the photosensitive member. However, the repeated use causes a problem that the surface of the organic photosensitive member is worn and the durability is insufficient. appear. Further, it is required to have sufficient durability against deterioration caused by ozone and nitrogen oxides generated during charging.

  For these reasons, a technique has been proposed in which a protective layer (hereinafter also referred to as a surface layer) is provided on the surface of the photoreceptor to improve the mechanical strength.

  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 photoreceptor has been proposed (see, for example, Patent Document 1 and Patent Document 2).

  Further, a technique for improving the mechanical strength by dispersing inorganic fine particles such as silica in a protective layer has been proposed (see, for example, Patent Document 3 and Patent Document 4).

JP 11-288121 A JP 2009-69241 A JP 2002-333733 A JP 2010-107962 A

  In recent years, the use of electrophotographic image forming apparatuses in the light printing field has been rapidly expanding, and electrophotographic photoreceptors are required to have higher durability and higher image quality. However, these conventional techniques cannot provide an electrophotographic photosensitive member that is sufficiently satisfactory in terms of durability and image quality, and further high durability and high image quality technologies have been desired for the electrophotographic photosensitive member.

  In order to improve the durability of an electrophotographic photosensitive member (hereinafter also referred to simply as a photosensitive member), it is effective to provide a protective layer with high wear resistance on the surface of the photosensitive layer. As this protective layer, a curable protective layer containing a reaction product of a radical polymerizable compound and metal oxide fine particles treated with a surface treatment agent having a reactive organic group such as an acryloyl group or a methacryloyl group is photosensitive. It is effective to provide it on the layer.

  However, if the hardness of the protective layer is too high, the rigidity of the protective layer increases and becomes brittle, and the wear of the protective layer tends to progress. This rigidity correlates with the content of the solvent used for forming the protective layer in the protective layer. When the amount of the solvent is small, the rigidity becomes high and the wear tends to proceed. In addition, when the content of the solvent is large, the rigidity decreases, but in the electrophotographic image forming process, holes generated by exposure are easily trapped in the solvent contained in the protective layer, and charge transfer is caused. Since it is not performed smoothly, image unevenness occurs. In particular, there arises a problem that a density difference due to the photoconductor cycle occurs in the printed image having the same density. Thus, it has been extremely difficult to achieve both improved wear resistance and image stability.

  The present invention has been made in order to solve the above-mentioned problems. An electrophotographic photoreceptor excellent in abrasion resistance, causing no difference in density due to the photoreceptor cycle, and having both abrasion resistance and stability of image characteristics is provided. It is intended to provide.

The above-described problems of the present invention are solved by the following configuration.
1. An electrophotographic photosensitive member in which at least a photosensitive layer and a protective layer are sequentially laminated on a conductive support, wherein the protective layer contains a reaction product of a radical polymerizable compound and metal oxide fine particles, and the protective layer The electrophotographic photoreceptor, wherein the solvent used for coating is at least one selected from alcohols and ketones, and the total amount of solvents contained in the protective layer is 20 ppm to 75 ppm .
2. 2. The electrophotographic photoreceptor according to 1 above, wherein the solvent used for coating the protective layer is a mixed solvent composed of one kind of alcohol and one kind of ketone.
3. 3. The electrophotographic photoreceptor according to 1 or 2 above, wherein the metal oxide fine particles are at least one selected from alumina fine particles, tin oxide fine particles, and titanium oxide fine particles.
4). The metal oxide fine particles are treated with a surface treatment agent, and the surface treatment agent is a compound containing at least one of an acryloyl group and a methacryloyl group. 2. The electrophotographic photosensitive member according to item 1.
5. Any one of 1 to 4 above, wherein the radical polymerizable compound is a polymerizable monomer having at least one of an acryloyl group and a methacryloyl group in the structure, or a polymerizable oligomer. The electrophotographic photosensitive member described.

  By adopting the above configuration, the present invention can provide a highly durable photoreceptor having high wear resistance and excellent image stability.

FIG. 3 is a schematic diagram illustrating an example of a layer configuration of a photoreceptor according to the present invention. 1 is a schematic cross-sectional view illustrating an example of an image forming apparatus using a photoreceptor according to the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  The photoreceptor of the present invention has a structure in which at least a photosensitive layer and a protective layer are sequentially laminated on a conductive support for the purpose of improving wear resistance. This protective layer contains at least a reaction product of a radical polymerizable compound and metal oxide fine particles. The metal oxide fine particles are preferably surface-treated with a radical polymerizable surface treatment agent having an acryloyl group or a methacryloyl group, whereby the radical polymerizable compound and the surface treatment agent of the metal oxide fine particles undergo a crosslinking reaction. The hardness of the protective layer can be further increased. This protective layer is formed by coating, and the solvent used for coating is selected from alcohols and ketones. After the protective layer is applied, it is dried and then cured by heat or light. At this time, it was found that when the total amount of alcohol and ketone used for coating the protective layer is 20 ppm or more and 75 ppm or less in the protective layer, both the wear resistance and image characteristics of the photoreceptor are satisfied. It is.

  The reason why both the wear resistance and the image characteristics are improved when the amount of the solvent contained in the protective layer (hereinafter also referred to as the amount of solvent contained) is in the above range is considered to be as follows.

  That is, if the amount of the solvent contained in the protective layer is small, the rigidity of the protective layer increases and the protective layer becomes brittle. For this reason, the wear of the protective layer proceeds due to friction caused by repeated use, and durability is lowered. When the content of the solvent is large, the protective layer is kept flexible to some extent, so that the wear resistance is improved. However, since the contained solvent acts as a hole trap, if the amount of the contained solvent is large, the change in potential characteristics becomes large, and this is manifested as a change in image density due to the period of the photoconductor. . That is, it is considered that when an image having the same density is printed, it appears as a difference in image density according to the period of the photosensitive member. That is, a difference in image density appears between the first and second rounds of the photoreceptor.

  In the present invention, by controlling the amount of solvent contained in the protective layer within the above range, it has been found that both the image density difference that appears depending on the period of the photoreceptor and the wear resistance of the protective layer can be achieved. And a highly durable photoconductor excellent in wear resistance.

≪Solvent amount≫
In the present invention, the protective layer of the photoreceptor is formed by coating with at least one solvent selected from alcohols and ketones. Moreover, the solvent used for coating of the protective layer is preferably a mixed solvent of one kind of alcohol and one kind of ketone. The amount of these alcohols, ketones and other solvents is 20 ppm to 75 ppm in the protective layer. More preferably, the amount of solvent in the protective layer is 40 ppm or more and 60 ppm or less. When the amount of the solvent is within this range, the wear resistance and image characteristics of the photoreceptor are stabilized. That is, at 20 ppm or less, the rigidity of the protective layer becomes too high and the wear resistance is poor. On the other hand, when the concentration is 75 ppm or more, the number of trapped holes increases and the amount of change in potential characteristics increases, and as a result, the image density difference in the photoreceptor period increases.

(Measurement method of solvent amount)
The amount of solvent contained in the protective layer can be measured by analyzing the charge transport layer and the protective layer with a gas chromatograph mass spectrometer. The amount of solvent in the protective layer in the present invention is a value measured as follows.

(sample)
The charge transport layer and the surface layer of the photoreceptor are peeled off with a cutter knife or the like, 0.1 g of the peeled film is put into a sample bottle having a volume of 20 ml, heated at 130 ° C. for 30 minutes, and headspace (HS) method. taking measurement.

(HS-GC / MS measurement conditions)
Measuring instrument: Gas chromatograph analyzer GC / HP6890 and MS / HP5973 (manufactured by Agilent Technologies)
GC column: DB-624 (inner diameter: 0.25 mm, length: 30 m, film thickness: 1.40 μm, part number 122-1334 (manufactured by Agilent Technologies))
GC column oven temperature: 40 ° C. (2 min) -10 ° C./min-100° C.-20 ° C./min-230° C. (5 min), () represents the holding time at the temperature.

Scan mass range: m / z 20-100
HS conditions: 130 ° C., 30 min
Carrier gas: high purity He (99.99 mass%), flow rate 1.2 ml / min, split ratio 20: 1
(Create a calibration curve)
A calibration curve was prepared using the standard substance and quantified.

≪Configuration of protective layer≫
(Radically polymerizable compound)
The radical polymerizable compound that can be used in the protective layer of the present invention is a polymerizable monomer or polymerizable oligomer having at least one of an acryloyl group and a methacryloyl group as a radical polymerizable reactive group.

  Examples of these polymerizable monomers and polymerizable oligomers include the following compounds, but the polymerizable monomers and polymerizable oligomers 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.

  Examples of the radical polymerizable compound of the present invention include the following radical polymerizable compounds in addition to the polymerizable compounds described above.

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

  The above radical polymerizable compound is easily synthesized by a known synthesis method, that is, starting from pentapentaerythritol, tetrapentaerythritol, pentapentaerythritol or the like as a starting material and performing an ester reaction with these with acrylic acid or methacrylic acid. I can do it.

(Metal oxide fine particles)
The metal oxide fine particles used in the protective layer of the present invention may be metal oxide particles including transition metals, such as silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide). ), Tin oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium dioxide, niobium oxide, molybdenum oxide, Metal oxide fine particles such as vanadium oxide are exemplified, among which fine particles of alumina (Al ₂ O ₃ ), tin oxide (SnO ₂ ), and titanium dioxide (TiO ₂ ) are preferable, and alumina and tin oxide are more preferable.

  The number average primary particle size of the metal oxide fine particles is preferably in the range of 1 to 300 nm. Especially preferably, it is 3-100 nm.

  The number average primary particle size of the metal oxide fine particles is a photographic image (excluding aggregated particles) obtained by taking an enlarged photograph of 10,000 times with a scanning electron microscope (manufactured by JEOL Ltd.) and randomly capturing 300 particles with a scanner. The automatic image processing analyzer “LUZEX AP” (manufactured by Nireco Corporation) software version Ver. The number average primary particle size was calculated using 1.32.

(Surface treatment agent)
The surface-treated metal oxide fine particles of the present invention are preferably those that have been surface-treated with a surface treatment agent having a radical polymerizable reactive group. The surface treating agent having a radical polymerizable reactive group is a radical polymerizable surface treating agent (hereinafter also referred to as a polymerizable surface treating agent) having reactivity with a hydroxyl group or the like present on the surface of the metal oxide fine particle, Any silane coupling agent having a radically polymerizable reactive group such as a group or acryloyl group may be used, and examples of the radically polymerizable surface treating agent having such reactivity include the following known compounds. .

_{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.

(Preparation of surface-treated metal oxide particles)
When the surface treatment is performed, a wet media dispersion type apparatus is used by using 0.1 to 100 parts by mass of the polymerizable surface treatment agent and the fluorine-containing surface treatment agent and 50 to 5000 parts by mass of the solvent with respect to 100 parts by mass of the particles. It is preferable to process. Moreover, it can also process by a dry type.

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

  That is, by subjecting a slurry (suspension of solid particles) containing metal oxide particles and a surface treatment agent to wet pulverization, the metal oxide particles are refined and the surface treatment of the particles proceeds at the same time. Thereafter, by removing the solvent and pulverizing, metal oxide particles that are uniformly surface-treated 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, thereby forming a metal oxide. It is an apparatus having a step of crushing and pulverizing and dispersing the agglomerated particles, as long as the metal oxide particles can be sufficiently dispersed and subjected to surface treatment when the surface treatment is performed on the metal oxide 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, metal oxide particles having a reactive organic group capable of reacting with a reactive acryloyl group and a reactive methacryloyl group can be obtained by surface treatment with a surface treating agent.

  Furthermore, the protective layer according to the present invention can be formed by using a known resin together with the compound obtained by the reaction.

  Known resins include polyester resins, polycarbonate resins, polyurethane resins, acrylic resins, epoxy resins, silicone resins, alkyd resins, and the like.

  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.

(Polymerization initiator)
In the present invention, the protective layer is formed by curing reaction of the polymerizable compound, but the 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. be able to. 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 zoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl Benzophenone photopolymerization initiators such as ether, acrylated benzophenone, 1,4-benzoylbenzene, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichloro Examples thereof include thioxanthone photopolymerization initiators such as thioxanthone.

  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 fine 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)
The solvent used for forming the protective layer is selected from alcohols and ketones. As the alcohol, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec- Butanol and benzyl alcohol are preferably used. Examples of ketones include, but are not limited to, methyl isopropyl ketone, methyl isobutyl ketone, methyl ethyl ketone, and the like. A particularly preferred solvent combination is sec-butanol and methyl isopropyl ketone.

(Formation of protective layer)
The protective layer is formed by exposing a coating solution prepared by adding a radical polymerizable compound, surface-treated metal oxide fine particles, and a known resin, a polymerization initiator, a lubricant particle, an antioxidant, and the like, if necessary, by a known method. It can be produced by applying to the surface of the layer, performing natural drying or heat drying, and then curing. 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 protective layer is cured by irradiating the coating film with active rays to generate radicals and polymerize, and then cure by forming a cross-linking bond between the molecules and within the molecule to form a cured resin. It is preferable to do. 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 100 to 300 kV. The absorbed dose is preferably 0.005 Gy to 100 kGy (0.5 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 from room temperature to 180 ° C, particularly preferably from 80 ° C to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes 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 >>
(Photoreceptor layer structure)
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 including the protective layer include the following.
(1) Layer configuration 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. Layer structure in which layer and protective layer are sequentially laminated (3) Layer structure in which intermediate layer, charge generation layer, charge transport layer and protective layer are sequentially laminated on conductive support (4) Conductive support A layer structure in which an intermediate layer, a single layer containing a charge transporting material and a charge generating material, and a protective layer are sequentially laminated on the photosensitive member of the present invention has any one of the above-mentioned layer structures (1) to (4). Among them, a layer structure in which an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer are sequentially provided on a conductive support is 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, and 7 is a surface-treated metal oxide fine particle.

  Next, the conductive support, intermediate layer, photosensitive layer (charge generation layer, charge transport layer) constituting the photoreceptor of the present invention, and members constituting the photosensitive layer 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 laminated on plastic film, aluminum, indium oxide or tin oxide deposited on plastic film, metal or plastic with conductive layer applied alone or with binder resin Examples include film and paper.

(Middle 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 kinds are mixed and used, they 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, 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. Further, 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 50-200 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 type layer structure has an advantage 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, and phthalocyanine pigments is not. These charge generation 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 weight, more preferably 50 to 500 parts by weight based on 100 parts by weight 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, 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. The pigment can also be formed by vacuum deposition.

(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.

  As the charge transport material, a known compound can be used, 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.

  Further, a known resin can be used as the binder resin for the charge transport layer, and examples thereof include the following. 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 preferable, 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 viewpoint of

  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.

(Photoreceptor application method)
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, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, and a circular amount-regulating coating method.

  The circular amount regulation type coating method is described in JP-A-58-189061.

≪Image forming device≫
An image forming apparatus according to the present invention will be described.

An image forming apparatus that realizes the effects of the present invention is as follows.
(1) An electrophotographic photosensitive member having at least the protective layer of the present invention,
(2) Charging means for charging the surface of the electrophotographic photosensitive member described above,
(3) An exposure unit that performs image exposure on the surface of the electrophotographic photosensitive member charged by the charging unit to form a latent image;
(4) developing means for visualizing the latent image formed by the exposure means to form a toner image;
(5) The image forming apparatus includes a transfer unit that transfers the toner image formed on the surface of the electrophotographic photosensitive member by the developing unit onto a transfer medium such as paper or a transfer belt.

  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 cross-sectional configuration diagram illustrating an example of a color image forming apparatus showing one of the embodiments 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 (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a 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. An 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, 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, and a primary transfer roller 5C as a primary transfer unit. It has 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 include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C and 3Bk, rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning unit 6Y or the cleaning blade 6Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 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 photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. In addition, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like 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.

  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 rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between 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. Consists of.

  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-treated metal oxide fine particles≫
(Preparation of surface-treated metal oxide fine particles 1)
100 parts by mass of “tin oxide” having a number average primary particle size of 20 nm as metal oxide fine particles and 30 parts by mass of “Exemplary Compound S-12” as a polymerizable surface treatment agent are mixed with 1000 parts by mass of methyl ethyl ketone. Bead) and mixed at 30 ° C. for 6 hours, and then methyl ethyl ketone and alumina beads were separated by filtration and dried at 60 ° C. to prepare “surface-treated metal oxide fine particles 1”.

(Preparation of surface-treated metal oxide fine particles 2)
In the production of the surface-treated metal oxide fine particles 1, “surface-treated metal oxide fine particles 2” were produced in the same manner except that 100 parts by mass of “alumina” having a number average primary particle size of 30 nm was used as the metal oxide fine particles. .

(Preparation of surface-treated metal oxide fine particles 3)
In the production of the surface-treated metal oxide fine particles 1, “surface-treated metal oxide fine particles 3” were produced in the same manner except that “titanium dioxide” having a number average primary particle size of 30 nm was used as the metal oxide fine particles.

(Preparation of surface-treated metal oxide fine particles 4)
In the production of the surface-treated metal oxide fine particles 1, “surface-treated metal oxide fine particles 4” were produced in the same manner except that “Exemplary Compound 15” was used as the polymerizable surface treating agent.

<< Production of Photoreceptor 1 >>
(Preparation of conductive support)
The surface of the cylindrical aluminum support was cut to prepare a conductive support having a surface roughness Rz = 1.5 (μm).

(Formation of intermediate layer)
A dispersion having the following composition was diluted twice 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.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part by mass Titanium oxide SMT500SAS (manufactured by Teica) 3 parts by mass Methanol 10 parts by mass Using a sand mill as a disperser, dispersion was carried out for 10 hours in a batch system.

  The said coating liquid was apply | coated and dried by the dip coating method so that it might become a dry film thickness of 2 micrometers on the said electroconductive support body, and the "intermediate layer" was formed.

(Formation of charge generation layer)
The following compositions were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution.

Charge generation material: titanyl phthalocyanine pigment (titanyl phthalocyanine pigment having a maximum diffraction peak at a position of at least 27.3 ° by Cu-Kα characteristic X-ray diffraction spectrum measurement) 20 parts by mass Polyvinyl butyral resin (# 6000-C: electrochemical 10 parts by mass t-butyl acetate 700 parts by mass 4-methoxy-4-methyl-2-pentanone 300 parts by mass This charge generation layer coating solution is applied onto the intermediate layer by a dip coating method and dried. Then, a “charge generation layer” having a dry film thickness of 0.3 μm was formed.

(Formation of charge transport layer)
The following composition was mixed and dissolved to prepare a charge transport layer coating solution.

Charge transport material (4,4′-dimethyl-4 ″-(β-phenylstyryl) triphenylamine) 225 parts by mass Binder: Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts by mass Antioxidant (Irganox 1010: BASF Japan) 6 parts by mass 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 This charge transport layer coating solution is placed on the charge generation layer with a circular amount regulating type coating machine. It was applied and dried to form a “charge transport layer” having a dry film thickness of 20 μm.

(Formation of protective layer)
The following composition was dissolved and dispersed to prepare a surface layer coating solution.

Surface-treated metal oxide fine particles 1 100 parts by mass Polymerizable compound (Exemplary compound M1) 100 parts by mass Polymerization initiator (Irgacure 819: manufactured by BASF Japan Ltd.) 7.5 parts by mass sec-butyl alcohol 360 parts by mass Methyl isopropyl ketone 90 Part by mass This surface layer coating solution was applied onto the charge transport layer using a circular amount-regulating coating device to form a surface layer. After drying the formed surface layer, the distance from the light source to the surface of the photoreceptor is set to 100 mm under a nitrogen stream using a metal halide lamp, and irradiated with ultraviolet rays for 1 minute at a lamp output of 4 kW. A “surface layer” was formed, and “photoreceptor 1” was produced.

  The charge transport layer and the protective layer of the photoreceptor 1 thus produced were peeled off. As described above, 0.1 g of the peeled film was analyzed by a gas chromatograph mass spectrometer (GC / HP6890 and MS / HP5973: manufactured by Agilent Technologies). The GC column uses DB-624 (inner diameter: 0.25 mm, length: 30 m, film thickness: 1.40 μm), holds the GC column oven temperature at 40 ° C. for 2 minutes, and at a rate of 10 ° C./minute. After the temperature was raised to 100 ° C., the temperature was raised to 230 ° C. at 20 ° C./min and held for 5 minutes for measurement. The scan mass range m / z at this time was 20-100, and the HS conditions were 130 ° C. and 30 min.

  The carrier gas is high purity He (99.99% by mass), the flow rate is 1.2 ml / min, the split ratio is 20: 1, HS is heated at 130 ° C. for 30 minutes, and the alcohol contained in the gas phase by the headspace method. When the total concentration of alcohol and ketone was measured as the amount of solvent, the total amount of solvent of alcohol and ketone was 47 ppm. The calibration curve was prepared by measurement using a standard sample.

<< Production of photoconductors 2-20 >>
In the photoreceptor 1, the amount of solvent is changed by changing the solvent type and amount of the surface layer coating solution, changing the amount of dry film thickness, changing the drying conditions before and after light irradiation after coating the protective layer, etc. 2-20 were produced. Table 1 below shows the composition, film thickness, drying conditions, and solvent content of each of the photoreceptors 1 to 20. Here, the photoreceptors 1 to 16 are the photoreceptors of the present invention, and the photoreceptors 17 to 20 are the photoreceptors for comparison.

≪Evaluation method and criteria≫
The photoconductor produced as described above was evaluated as follows.

(Abrasion resistance of photoreceptor surface)
The electrophotographic photosensitive member of the present invention is mounted on “bizhub PRO C6500” (tandem color composite machine of laser exposure / reversal development / intermediate transfer body at a wavelength of 780 nm) manufactured by Konica Minolta Business Technologies, Inc. (30 ° C., 85% RH). ) Yellow (Y), magenta (M), cyan (C), and black (Bk) A4 plate images of 5% color printing area ratio are printed on neutral paper of A4 plate, and the initial film The thickness and the film thickness after 1 million sheets were evaluated. The photosensitive layer has a uniform thickness (measured at 10 locations at random, excluding at least 3 cm at both ends because the film thickness tends to be non-uniform at both ends of the photoconductor). To do. The film thickness measuring device is an eddy current film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in the photosensitive layer thickness before and after the actual shooting test is defined as the film thickness depletion amount.

  Specifically, the following α value was evaluated.

α value = {(thickness loss in the depth direction [μm]) / total number of revolutions of drum} × 100,000
That is, the smaller the α value, the higher the wear resistance.

(Density step)
A halftone image (average relative reflection density 0.4 by Macbeth densitometer) is copied on the entire surface of A3 neutral paper with the above-mentioned multi-function machine, and longitudinally at a position 180 mm laterally from the corner of the A3 paper (vertical 297 mm × width 420 mm). Macbeth is defined as a total of 8 points at intervals of 33 mm from the end of the frame, a1 and a2 to a8, respectively, and a total of 8 points at intervals of 195 mm in the horizontal direction from the corner and 33 mm from the end of the vertical direction is b1, b2 to b8. The reflection density at each point was measured with a densitometer. The difference between the measurement values of a1 and b1, the difference between the measurement values of a2 and b2, and the difference of the measurement values of a total of eight combinations were evaluated.

A: Maximum difference in measured values is less than 0.01 (good)
○: The maximum difference between measured values is 0.01 or more and less than 0.02 (no problem in practical use)
Δ: The maximum difference between the measured values is 0.02 or more and less than 0.04 (practical use)
×: The maximum difference between the measured values is 0.04 or more (there is a problem in practical use)

  As is apparent from the results in Table 2, it can be seen that the photoconductors 1 to 16 of the present invention are extremely excellent in both wear resistance and density difference characteristics as compared with the photoconductors 17 to 20 for comparison. .

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 7 Surface treatment metal oxide fine particle 1Y, 1M, 1C, 1Bk Photosensitive drum 2Y, 2M, 2C, 2Bk Charging means 3Y, 3M, 3C, 3Bk Image exposure means 4Y, 4M, 4C, 4Bk Developing means 6Y, 6M, 6C, 6Bk Cleaning means 10Y, 10M, 10C, 10Bk Image forming unit

Claims (5)

  An electrophotographic photosensitive member in which at least a photosensitive layer and a protective layer are sequentially laminated on a conductive support, wherein the protective layer contains a reaction product of a radical polymerizable compound and metal oxide fine particles, and the protective layer The electrophotographic photoreceptor, wherein the solvent used for coating is at least one selected from alcohols and ketones, and the total amount of solvents contained in the protective layer is 20 ppm to 75 ppm .   2. The electrophotographic photoreceptor according to claim 1, wherein the solvent used for coating the protective layer is a mixed solvent composed of one kind of alcohol and one kind of ketone.   The electrophotographic photosensitive member according to claim 1, wherein the metal oxide fine particles are at least one selected from alumina fine particles, tin oxide fine particles, and titanium oxide fine particles.   The metal oxide fine particles are treated with a surface treatment agent, and the surface treatment agent is a compound containing at least one of an acryloyl group and a methacryloyl group. The electrophotographic photosensitive member according to any one of the above.   5. The method according to claim 1, wherein the radical polymerizable compound is a polymerizable monomer or polymerizable oligomer having at least one of an acryloyl group and a methacryloyl group in the structure. The electrophotographic photosensitive member according to Item.

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