JPH0267566A - Electrophotographic sensitive body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to a highly durable electrophotographic photoreceptor with excellent moisture resistance and mechanical strength.

[Prior Art] Electrophotographic photoreceptors are required to have predetermined sensitivity, electrical properties, and optical properties depending on the electrophotographic process to which they are applied. In this case, the surface layer of the photoreceptor, that is, the layer furthest away from the support, has corona charging, toner development, transfer to paper,
Since electrical and mechanical external forces such as cleaning processes are directly applied, durability against these forces is required.

Specifically, durability is required against surface abrasion and scratches due to rubbing, and surface deterioration due to ozone generated during corona charging under high humidity.

On the other hand, there is also a problem of toner adhesion to the surface layer due to repeated toner development and cleaning processes, and to solve this problem, it is required to improve the cleaning properties of the surface layer.

Various methods have been studied to satisfy the above-mentioned characteristics required for the surface layer, and among them, the method of dispersing fluororesin powder in the surface layer is effective.

The dispersion of fluororesin powder reduces the coefficient of friction of the surface layer, which improves cleaning performance and durability against abrasion and scratches.

Furthermore, since the water repellency and mold releasability of the surface layer are improved, it is also effective in preventing surface deterioration under high humidity.

However, dispersion of fluororesin powder has problems with its dispersibility and cohesiveness, making it difficult to form a uniform and smooth film, so the resulting surface layer has image defects such as unevenness and pinholes. It was unavoidable to have.

Therefore, one method of uniformly dispersing fluororesin powder and forming a smooth film has been proposed by using a surfactant as a dispersion aid. It is being considered to further reduce the amount of wear on the photoreceptor and extend the life of the photoreceptor by increasing the amount.

As the amount of fluororesin powder increases, the amount of surfactant, which is a dispersion aid, must also be increased.As the amount of surfactant increases, the coating solution foams.1 The generated foam is difficult to disappear. A problem arose.

Also, electrophotographic photoreceptors with increased surfactant content.

This caused deterioration of electrophotographic properties such as a decrease in sensitivity due to repeated use and a decrease in sensitivity in high temperature and high humidity environments.Furthermore, in a functionally separated photoreceptor that is made by sequentially laminating a conductive support, a charge generation layer, and a charge transport layer. It has been proposed that additives such as oxidation inhibitors be added to the charge transport layer in order to prevent the charge transport layer, which is the surface layer, from deteriorating due to charged products such as ozone and NOx. It has been found that the coexistence of the above-mentioned surfactant, which is a dispersion aid for the fluororesin powder, causes further deterioration of the electrophotographic properties.

Electrophotographic photoreceptors to which fluororesin powder is added have various problems.

[Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor that meets the above-mentioned requirements.

That is, the first objective is to provide an electrophotographic photoreceptor that is durable against surface abrasion and scratches caused by rubbing, and the second objective is to provide stable, high-quality images even under high humidity conditions. The third purpose is to provide an electrophotographic photoreceptor that has good cleaning properties and does not have toner adhesion to the surface layer. The fifth objective is to provide an electrophotographic photoreceptor that does not cause deterioration of electrophotographic properties due to dispersion aids, and provides an electrophotographic photoreceptor that does not accumulate residual potential during repeated electrophotographic processes and can always produce high-quality images. It's about giving your body.

[Means and Effects for Solving the Problems] As a result of intensive research in accordance with the above objectives, the present inventors have found that an electrophotographic photoreceptor having a surface layer in which fluororesin powder subjected to surface oxidation treatment is dispersed satisfies the above requirements. The present invention was completed based on the finding that it answers the following questions.

Specifically, the present invention relates to an electrophotographic photoreceptor having a photosensitive layer on a conductive support, the surface layer of which contains a fluororesin powder subjected to surface oxidation treatment. configured.

In the present invention, since the surface-oxidized fluororesin powder is uniformly dispersed in the paint film, there is no need to add a large amount of surfactant, and no bubbles are generated in the paint.

The fluororesin powders applicable to the present invention are tetrafluoroethylene resin, trifluorochloride ethylene resin, tetrafluoroethylene hexafluoride propylene resin, vinyl difluoride resin, nylidene heptafluoride resin, and chloride difluoride resin. One or more types of ethylene resins and copolymers thereof are appropriately selected, and in particular, four ethylene resins 1. 41 Near Fluorinated Ethylene Resin, ゛Resin is preferred, and the molecular weight and powder particle size of the resin can be appropriately selected from commercially available grades.

The content of the fluororesin powder dispersed in the surface layer is suitably 1 to 50%, particularly preferably 2 to 30%, based on the solid weight of 1 surface.

If the content is less than 1%, the surface layer modification effect by the fluororesin powder will not be sufficient, while if it exceeds 50%, the light transmittance will decrease and carrier mobility will also decrease.

Furthermore, as a surface oxidation treatment method for the fluororesin powder in the present invention, surface treatment methods such as corona discharge treatment, ozone treatment, and chemical treatment can be used.

As the corona discharge treatment method, AC corona charging is preferably performed by negative polarity charging.

As the oson treatment method, treatment by ultraviolet light irradiation is preferred.

As a chemical treatment method, it is preferable to use a mixed acid of sulfuric acid and chromic acid, a solution prepared by adding sodium to liquid ammonia, or the like.

The binder resin for forming the surface layer may be any polymeric material that has film-forming properties, but polymethacrylate ester is used because it has a certain degree of hardness even when used alone and does not interfere with carrier transport. , polystyrene, methacrylic acid ester/styrene copolymer, polycarbonate, polyarylate, polyester, polysulfone, and the like are preferred.

When producing the electrophotographic photoreceptor of the present invention, a cylindrical cylinder or film made of metal such as aluminum or stainless steel, paper, or plastic is used as the support.

A subbing layer (adhesive layer) having a barrier function and a subbing function can be provided on these supports.

The undercoat layer improves the adhesion and coating properties of the photosensitive layer.

It is formed for purposes such as protecting the support, covering defects on the support, improving charge injection from the support, and protecting the photosensitive layer from electrical breakdown.

The material for the undercoat layer is polyvinyl alcohol poly-N.
- Vinylimidazole, polyethylene oxide, eryl cellulose, methyl cellulose, ethylene/acrylic acid copolymer, casein, polyamide, copolymerized nylon, glue, gelatin, etc. are known. These are each dissolved in a suitable solvent and applied onto a support. The thickness of the film is about 0.2 to 2 m.

Charge-generating substances include cyanine dyes, azulene dyes, scuvialylium dyes, biryllium dyes, thiapyrylium dyes, phthalocyanine pigments, andanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, monoazo pigments, and disazo pigments. Pigments, azo pigments such as tris-7zo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine, quinocyanine, etc. can be used.

As the charge transport substance, carbazole-based substances such as N-isopropylcarbazole, N-methyl-N-phenylhydrazino-3-methylten-9-ethylcarbazole, and N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole are used. Compound, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1,3.3-trimethylindolenine-
ω-Aldehyde-N, N-diphenylhydrazone, p-
Hydrazone compounds such as diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 1-
[pyridyl(2)]3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-
Pyrazoline compounds such as methyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 2-(p-diethylaminostyryl)-6-dinithyl 7minobenzoxazole 2-(p-diethylaminomethyl )-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, thiazole-based compounds such as 2-(p-diethylamino/styryl)6-ethylaminobenzthiazole, bis( Triarylmethane compounds such as 4-diethylamino-2-methylphenyl)phenylmethane, 1,1-bis(4-N.

N-diethylamino-2-methylphenyl)hebutane,
Polyarylalkanes such as 1,1,2.2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, 5-(4-diphenylaminobenzylidene)-5H dibenzo[ad]cycloheptene, 1 , 2-benzo-3-(α-7enylstyryl)-9-n-butylcarbazole and other stilbene-based compounds can be used.

The production of the electrophotographic photoreceptor of the present invention will be explained using an example of a functionally separated type photoreceptor in which a charge transport layer is laminated on a charge generation layer.

The above charge generating material is well dispersed together with a binder resin and a solvent in an amount of 0.3 to 10 times using a homogenizer, an ultrasonic wave, a ball mill, a vibrating ball mill, a sand mill attritor, a roll mill, or the like. This dispersion was coated on the support coated with the subbing layer, dried, and 0.1-11-
A coating film of 1p degree is formed.

In this example, since the surface layer becomes the charge transport layer, the fluororesin powder is dispersed therein.Prior to dispersion, the fluororesin powder is subjected to the corona discharge treatment, ozone treatment, and the like described above. Use one whose surface has been modified by chemical treatment.

After the surface treatment, the fluororesin powder is passed through a homogenizer together with the binder resin, fluororesin powder, and solvent.
Dispersion is performed using an ultrasonic wave, a ball mill, a vibrating ball mill, a sand mill, an attritor, a roll mill, etc., and a solution of a charge transport substance and a binder resin is added thereto to prepare a desired charge transport layer coating solution.

The mixing ratio of charge transport material and binder resin is 2:l-
The ratio is about 1:4.

As the solvent, aromatic hydrocarbon compounds such as toluene and xylene, chlorine hydrocarbon compounds such as dichloromethane, chlorobenzene, chloroform, and carbon tetrachloride are used.

When applying this solution, coating methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, and curtain coating can be used, and drying is carried out at 10 to 200°C. , preferably 20~
It can be carried out at a temperature in the range of 150° C. for 5 minutes to 5 hours, preferably under static drying.

The thickness of the formed charge transport layer is about 10 to 30 gm.

Furthermore, in the case of a photoreceptor in which a charge generation layer is coated on a charge transport layer, the charge generation layer is a surface layer, and therefore contains fluororesin powder subjected to surface oxidation treatment.

This charge generation layer coating solution is prepared by adding and mixing a dispersion of surface oxidized fluororesin powder dispersed in a binder resin used for the charge generation layer to a dispersion of a charge generation substance prepared as described above. Can be prepared by the method
The electrophotographic photoreceptor of the present invention can be produced by coating the prepared coating liquid on the charge transport layer to form a charge generation layer.

Further, when a protective layer is provided on the photosensitive layer and the protective layer serves as a surface layer, the fluororesin powder subjected to surface oxidation treatment is contained in this protective layer.

This protective layer can be formed by coating the photosensitive layer with a protective layer coating solution prepared by adding and mixing a dispersion of a fluororesin powder subjected to surface oxidation treatment to a resin forming the protective layer as described above.

[Example] Example 1 Method for surface oxidation treatment of fluororesin powder (i) Corona discharge treatment Polytetrafluoroethylene (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) powder was used as the fluororesin powder. Spread this evenly on a stainless steel container to a thickness of about 2 mm, and then spread it over a stainless steel container with a width of 25 mm, a height of 15 mm,
A corona charger with a length of 340 mm (7) made of stainless steel and a tungsten wire with a thickness of 60 pm was used to apply a voltage of -6 KV and a total current of -200 gA.
Corona discharge treatment was performed under the following discharge conditions while maintaining the distance between the tungsten wire and the polytetrafluoroethylene at approximately 20 mm. In order to perform the treatment uniformly, the stainless steel container was moved back and forth at a speed of 20 cm/mh, and corona discharge was performed so that the corona discharge time per unit area was 2 minutes/Cm2.

The fluororesin powder subjected to this surface oxidation treatment was
shall be.

(if) Polytetrafluoroethylene powder is used as the ozone-treated fluororesin powder, and it is evenly sprinkled on a stainless steel container to a thickness of about 5 mm, and the ozone atmosphere tank (type 0-3 -2
1. (manufactured by Kanayama Rika Kogyo ■), and the ozone concentration is 300pp.
Ozone treatment was performed for 20 minutes at m.

This surface oxidized fluororesin powder is No. 2.
shall be.

(iii) Put 200 g of polytetrafluoroethylene powder into a chemically treated glass beaker, and add sulfuric acid/chromic acid mixture (K2 Cr207
;H20;H2SO4=4.4.88.5;7.1
ffi amount ratio) was added, stirred lightly with a glass rod, allowed to stand for 30 seconds, and then filtered to separate polytetrafluoroethylene.

After this chemical treatment, the polytetrafluoride ethyl chloride was dried for 3 hours in a hot air dryer heated to 80°C.

This surface oxidized fluororesin powder is No. 3.
shall be.

Example 2 An aluminum cylinder of 80 mmφ x 360 mm was used as a support, and polyamide (trade name Amilan CM-4)
A 5% methanol solution of 000, manufactured by Toshi ■ was applied by dip coating to form a subbing layer of 1 lm. Next, 10 parts of disazo pigment of the following structural formula (weight ratio, same hereinafter) was applied.Polyvinyl butyral (product) 5 parts of Meiko Sletsku BM-2 (manufactured by Miki Kagaku Kogyo Mari) and 50 parts of cyclohexanone were dispersed for 200 hours in a sand mill using 1 mm diameter glass beads. Add methyl ethyl ketone 7O-120 to this dispersion.
(appropriate) and coated on the undercoat layer to a film thickness of 0.20 μm.
A charge generation layer of m was formed.

Next, 10 parts of polymethyl methacrylate (trade name: Dyanal BR-85, manufactured by Mitsubishi Rayon ■) and 10 parts of the above N091 fluororesin powder were dissolved in 40 parts of chlorobenzene and 30 parts of tetrahydrofuran, and the mixture was heated in a stainless steel ball mill. Dispersed for 48 hours. For 10 parts of the obtained dispersion, p-diethylaminobenzaldehyde-N-α
-10 parts of naphthyl-N-phenylhydrazone and 10 parts of polymethyl methacrylate (mentioned above) were added to 60 parts of chlorobenzene.
A charge transport layer coating solution was prepared by mixing 70 parts of a resin solution dissolved in 1 part with 70 parts of a resin solution.

The average particle size of the polytetrafluoroethylene powder in this charge transport layer coating solution was measured using a particle size distribution analyzer (trade name: CAPA-500).
, Measured L with v4m field address)? .

It was 0.46 JLm.

This coating solution was applied onto the charge generation layer and dried with hot air for 110"090 minutes to form a charge transport layer of 18 gm.

The surface of the obtained charge transport layer was uniform and smooth, and the average surface roughness was 0.2 pm.

The electrophotographic photoreceptor thus produced is designated as sample 1.

For comparison, an electrophotographic photoreceptor was prepared in the same manner as described above using a fluororesin powder (polytetrafluoroethylene powder) that had not been subjected to the surface oxidation treatment, and this was designated as Sample 2.

Sample 2 had severe agglomeration of the polytetrafluoroethylene powder in the surface layer, and was not worthy of image evaluation.

Further, an electrophotographic photoreceptor was prepared in the same manner as above except that the fluororesin powder was not added.

This is designated as sample 3.

Each of these samples is processed using an electrophotographic copying machine (product) that has an electrophotographic process consisting of primary charging, image exposure, dry toner development, transfer of the toner image to transfer paper, separation of the transfer paper from the photoreceptor, cleaning, and pre-exposure. The initial image characteristics and durability characteristics were evaluated using NP-3725 (manufactured by Canon ■).

First, the initial image characteristics are such that the photoreceptor surface potential at the developing machine position is -650V for the black background of the original and -130V for the white background.
Position 1 of the discharge wire of the primary charger so that
Initial images were obtained by adjusting the lighting voltages of the halogen lamps used in the image exposure device so that each sample had the same latent image potential.

In addition, regarding durability characteristics, after initial image evaluation.

Durability evaluation was carried out on 30,000 sheets under the same conditions as normal temperature, normal humidity, 23° C., 155% RH, high temperature, 32.5° C., and 90% RH. Show the results.

Sample Initial image 1 Good 2 Fully blank 3 Good sample 23℃, 55% RH Sample with toner fused to the surface at 32.5°C, 90% RH Chukyu 1 Durability High quality and stable image up to 30,000 sheets 2 Not worthy of evaluation 3 Image deletion occurred after 4,000 sheets Example 3 Example 2 Subbing layer 1 on the support using the same materials and method
A charge generation layer was then formed.

Next, 10 parts of bisphenol Z type polycarbonate (manufactured by Mitsubishi Gas Chemical ■), 2 fluororesin powders of No. 2 above,
0 parts to Schiff a, 50 parts of xanone, 2 parts of tetrahydrofuran
0 parts, and dispersed for 20 hours in a sand mill using glass beads of 1 mm diameter.

To 10 parts of the obtained dispersion, 70 parts of a resin solution in which 12 parts of a pyrazoline compound having the following structural formula and 10 parts of the above bisphenol Z type polycarbonate were dissolved in 40 parts of cyclohexanone and 20 parts of tetrahydrofuran were mixed.

A charge transport layer coating solution was prepared.

The average particle size of the polytetrafluoroethylene powder in this coating solution was 0.45 m.

Coating this charge transport layer coating solution on the charge generation layer,
110" was dried with hot air for 0.90 minutes to form a charge transport layer of 20 parts m. The surface roughness was 0.2 pm or less. The electrophotographic photoreceptor thus prepared was designated as Sample 4.

For comparison, an electrophotographic photoreceptor was prepared in the same manner as described above using a fluororesin powder (polytetrafluoroethylene powder) that had not been subjected to the surface oxidation treatment, and this was designated as Sample 5.

Sample 5 was in a state where the agglomeration of the polytetrafluoroethylene powder in the surface layer was so severe that it was not worthy of single-image evaluation.

Further, an electrophotographic photoreceptor was prepared in the same manner as above except that the fluororesin powder was not added.

This is designated as sample 6.

For each sample, durability evaluation was performed on 30,000 sheets in the same manner as in Example 2. Show the results.

Sample Initial image 4 Good 5 All white spots 6 Good sample 23°C, 55% RH # Long 4 High quality and stable image up to 30,000 sheets 5 Not worthy of evaluation 6 Toner fused sample at 6,000 sheets 32.5°C , 90% RH# Long 4 High-quality and stable images up to 30,000 copies 5 Not worthy of evaluation 6 Image deletion occurred after 5,000 copies Example 4 0.0. 5#
A subbing layer of Lm was formed.

Next, add 10 parts of a disazo pigment having the following structural formula.

Polyvinyl butyral (product name: Kosurek BL-5.I
6 parts (manufactured by A Water Kagaku ■) and 50 parts of cyclohexanone in 1
The mixture was dispersed for 20 hours using a sand mill using mmφ glass beads.

100 parts of tetrahydrofuran was added to this dispersion and applied onto the undercoat layer to form a charge generation layer with a thickness of 0.2° C.m.

Next, 10 parts of the bisphenol Z-type polycarbonate used in Example 2 and 10 parts of the N013 fluororesin powder were dissolved in 50 parts of dichloromethane and 10 parts of chlorobenzene, and the mixture was milled in a sand mill using 1 mm diameter glass beads for 2 hours.
Dispersed for 0 hours.

To 10 parts of the obtained dispersion, 10 parts of a stilbene compound having the following structural formula and 70 parts of a resin solution prepared by dissolving 10 parts of the above bisphenol Z type polycarbonate in 50 parts of dichloromethane and 10 parts of chlorobenzene were mixed to conduct charge transport. A layer coating solution was prepared, and 1,3,5-)dimethyl-2,4,6-tris(3
, 5-di-tert-butyl-4-hydroxybenzyl)benzene was added in total, and the mixture was coated on the charge generation layer.
IT L, hot air drying at 110°C for 90 minutes to form a 20 lm charge transport layer.

This electrophotographic photoreceptor will be referred to as Sample 7.

For comparison, an electrophotographic photoreceptor was prepared in the same manner as above using fluororesin powder (polytetrafluoroethylene powder) that had not been subjected to the surface oxidation treatment, and this was designated as Sample 8.

Try it! Sample No. 48 had severe agglomeration of the polytetrafluoroethylene powder in the surface layer and was not worthy of image evaluation.

Further, an electrophotographic photoreceptor was prepared in the same manner as above except that the fluororesin powder was not added.

This is designated as sample 9.

For each sample, durability evaluation was performed on 30,000 sheets in the same manner as in Example 2. Show the results.

Sample Initial image 7 Good 8 All white spots 9 Good sample 23℃, 55% RH#Ku 7 High quality and stable image up to 30,000 sheets 8 Not worthy of evaluation 9 Toner fused sample at 6,000 sheets 32.5℃ , 90% RH Durability 7 High quality and stable image up to 30,000 copies 8 Not worthy of evaluation 9 Image deletion occurs after 5,000 copies Example 5 With 10 parts of the stilbene compound used in Example 4.

10 parts of the polycarbonate used in Example 2 was dissolved in 50 parts of dichloromethane and 10 parts of chlorobenzene. This solution was used as a corridor in Example 3, and a subbing layer was applied to the 80mmφ
A charge transport layer of 12JLm was formed by dip coating on an aluminum cylinder of 360mm xoo'c and drying for an hour.

Next, the surface oxidation treatment used for the fluororesin powder of N011 was applied to polytrifluorochloroethylene powder (manufactured by Daikin Corporation).
10 parts of the obtained fluororesin powder and 10 parts of the same disazo pigment used in Example 3. 3,5
- 0.6 parts of di-tart-butyl-4-hydroxybenzyl)benzene to 10 wt% of the above polycarbonate.
The mixture was added to 100 parts of cyclohexanone solution and dispersed in a stainless steel ball mill for 50 hours.

This dispersion is applied onto the charge transport layer.

A charge generation layer having a thickness of 3 gm was formed by dry bombing at IoO'C for 20 minutes. The average particle size of the polytrifluorochloroethylene powder in this charge generation layer was 0.5 pm, and the surface roughness was 0.2 gm or less.

The produced electrophotographic photoreceptor is referred to as Sample 10.

For comparison, an electrophotographic photoreceptor was prepared in the same manner as above using a fluororesin powder (polytrifluorochloroethylene powder) that had not been subjected to the surface oxidation treatment, and this was used as sample 1.
Set to 1.

Sample 11 was in a state where the agglomeration of the polytrifluorochloroethylene powder in the surface layer was so severe that it was not worth a single image evaluation.

Further, an electrophotographic photoreceptor was prepared in the same manner as above except that the fluororesin powder was not added.

This is designated as sample 12.

For each sample, the polarity of the primary charging and transfer charging of the electrophotographic copying machine used in Example 2 was changed to positive polarity using an external power supply.
The toner is also of reverse polarity, NP-7500 machine (Canon ■
In the same manner as in Example 2, the durability of initial images and 10,000 sheets was evaluated using the same method as in Example 2. Show the results.

Sample Initial image lO good 11 All white spots 12 Good sample 23℃, 55%RH 90%RH#Kyu to 1
High-quality and stable image up to 10,000 copies 11 Not worthy of evaluation 12 Image deletion occurred after 2,000 copies Example 6 0, 5 images were printed on a support using the same materials and method as Example 2
A subbing layer of 1 part m was applied.

Next, a charge generation layer similar to that in Example 3 was applied on top of this to a thickness of 0.2 m.
It was applied thickly.

Furthermore, on top of this, 10 parts of bisphenol A type polycarbonate was dissolved in 60 parts of a mixed solvent of dioxane and dichloromethane, and further 10 parts of the charge transport material used in Example 3,
Additive 1,3.5-)dimethyl-2,4,6-tris(
A solution containing 0.3 parts of 3,5-di-tert-butyl-4-hydroxybenzyl)benzene was applied by dip coating to a thickness of 18 ILm, and dried at 100°C for 1 hour to form a charge transport layer. The electrophotographic photoreceptor thus produced is designated as Sample 13.

Further, on top of this charge transport layer, 2 parts of the bisphenol Z type polycarbonate used in Example 2 was dissolved in 30 parts of dichloromethane, and the fluororesin powder No. 2 was added to this.
A protective layer having a thickness of 1 m was formed by applying a solution prepared by adding 1 part of the following and dispersing it in a stainless steel ball mill for 50 hours.

This electrophotographic photoreceptor will be referred to as Sample 14.

For comparison, an electrophotographic photoreceptor was prepared in the same manner as described above using a fluororesin powder (polytetrafluoroethylene powder) that had not been subjected to the surface oxidation treatment, and this was designated as Sample 15.

Sample 15 was in a state where the agglomeration of the polytetrafluoroethylene powder in the surface layer was so severe that it was not worth a single image evaluation. For each sample, durability evaluation was performed on 30,000 sheets in the same manner as in Example 2. . Show the results.

Sample Initial image 13 Good 14 Good 15 Fully white spot sample 23°C, 55% RH #13 Toner fusion at 7,000 sheets 14 High quality and stable image up to 30,000 sheets 15 Sample not worthy of evaluation 32.5°C ,90%RHjl)lkyu13
Image blurring occurs after 6,000 sheets 14 High-quality and stable images up to 30,000 sheets 15 Not worthy of evaluation [Effects of the invention] In photographic photoreceptors, fluororesin powder is uniformly dispersed and its dispersion stability is improved, so a uniform surface layer is always obtained, and as a result, not only the initial image but also after repeated durability. You can always obtain high-quality images without scratches or image deletion.

By using fluororesin powder that has undergone surface oxidation treatment, surfactants are no longer necessary, so the generation of bubbles in the paint is eliminated, and high image quality without single image defects can be provided.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, the surface layer of which contains a fluororesin powder subjected to surface oxidation treatment.