JPS6373267A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance durability due to abrasion and scratching of the surface of the electrophotographic sensitive body by using a resin layer obtained by incorporating a fluororesin into a binder using a fluorine-contained organic solvent as a layer located farthest from a substrate. CONSTITUTION:The electrophotographic sensitive body having a photosensitive layer on a conductive substrate has the layer located farthest from the conductive substrate formed by using a liquid dispersion containing a powder of the fluororesin, preferably, such as tetrafluoroethylene or vinylidene fluoride resin, and the fluorine-contained organic solent, such as benzotrifluoride, benzoyl fluoride, benzyl fluoride, n-butyl trifluoroacetate, or hexafluoro-benzene, thus permitting dispersion stability of the fluororesin powder to be enhanced, and deterioration of the electrophotographic characteristics to be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and particularly to a highly durable electrophotographic photoreceptor having excellent mechanical strength, surface lubricity, temperature resistance, and imageability.

[Prior Art 1 Electrophotographic photoreceptors are required to have predetermined sensitivity, electrical properties, and optical properties depending on the electrophotographic process to which they are applied, but in addition, in photoreceptors that are used repeatedly, The surface layer of the photoreceptor, that is, the layer furthest from the substrate, is charged with corona.

Since electrical and mechanical external forces such as toner development, transfer to paper, and cleaning processing 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 the problem of toner adhesion to the surface layer due to toner development and edge turning during cleaning, and to solve this problem, it is required to improve the cleaning performance of the surface layer.

Various methods have been studied to satisfy the above-mentioned characteristics required for the surface layer, but among them, providing a surface layer in which fluororesin powder is dispersed is particularly effective.

Providing a surface layer in which fluorine-containing resin powder is dispersed improves durability against scratches, surface cleaning, and abrasion, and also improves the water repellency and mold release properties of the photoconductor surface, making it suitable for use under high humidity conditions. It is also effective in preventing surface deterioration.

Furthermore, when a protective layer is provided on the surface, charge transporting materials and charge generating materials that are susceptible to deterioration by ozone are isolated from the surface, further improving durability.

However, when dispersing fluororesin powder, there are problems with its dispersibility and cohesiveness, making it difficult to form a uniform and smooth film. It was inevitable that the image would have defects.

In addition, bindu resins or dispersion aids that have good dispersibility often cause deterioration of electrophotographic properties in most cases, and it is currently impossible to find anything effective.

[Problems to be Solved by the Invention] An object of the present invention is to provide an electrophotographic photoreceptor that has durability against surface abrasion and scratches caused by rubbing and satisfies the above-mentioned drawbacks. It is.

Another object of the present invention is to provide an electrophotographic photoreceptor that is free from coating unevenness and pinholes on its surface, and free from residual potential in repeated electrophotographic processes, allowing high-quality images to be obtained at all times.

[Means for Solving Problems 1 Effect] In the present invention, as a result of repeated studies to solve the above problems, a resin layer in which fluorine-containing resin powder is dispersed in a binder using a fluorine-containing organic solvent is provided. By employing this in the layer furthest away from the substrate, it has become possible to provide an electrophotographic photoreceptor that meets the above requirements.

That is, the present invention provides an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, in which at least the layer furthest from the substrate is formed using a dispersion containing at least a fluorine-containing resin powder and a fluorine-containing organic solvent. The fluorine-containing resin powder used in the present invention includes tetrafluoroethylene, trifluorochloroethylene, and hexafluoroethylene. Polymers such as ethylene propylene, vinyl fluoride, vinylidene fluoride, ethylene difluoride dichloride, trifluoropropylmethyldichlorosilane, or their copolymers or copolymer resin powders with vinyl chloride are used as appropriate. However,
Particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin.

The molecular weight of the resin and the particle size of the powder can be selected as appropriate.

Furthermore, in the present invention, it is also effective to add small amounts of additives such as various surfactants, coupling agents, silicone oils, and leveling agents as dispersion aids in order to further increase the dispersion effect.

In this case, even if the additive itself affects the electrophotographic properties, by using it together with the fluorine-containing organic solvent,
The amount added can be kept to an extremely small amount, and the influence on electrophotographic properties can be kept to a level that causes no practical problems.

Examples of the fluorine-containing organic solvent used in the present invention include pensitrifluoride, benzoyl fluoride, benzyl fluoride, n-butyl trifluoroacetate, P-chlorobensitrifluoride, 1,3-di(trifluoromethyl)benzene, , 5-di(trifluoromethyl)benzonitride, fluorobenzene, P-fluorotoluene, hexafluorobenzene, etc.
Further, these may be used in combination with other organic solvents, such as monochlorobenzene, dichloromethane, 2-butanone, dioxane, toluene, xylene, tetrahydrofuran, and other resin-soluble solvents.

When the fluororesin powder is dispersed in the binder using the above solvent, the dispersibility and dispersion stability of the fluororesin powder are improved, and agglomeration of the fluororesin powder is prevented during coating film formation. As a result, an extremely uniform and smooth fluororesin dispersion layer is formed.

The content of the dispersed fluorine-containing resin powder is suitably 1 to 50%, particularly 5 to 40% by weight, based on the weight of the total solid content contained in the layer furthest from the conductive substrate.

The binder resin used for dispersion may be any polymer with film-forming properties, but polymethacrylate, polycarbonate, polyarylate, and polyester are recommended because they have a certain degree of hardness even when used alone and do not interfere with carrier transport. , polysulfone, etc. are preferred.

When manufacturing 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 substrate. A subbing layer (adhesive layer) having a barrier function and a subbing function can be provided on these substrates.

The undercoat layer is formed to improve adhesion of the photosensitive layer, improve coating properties, protect the substrate, cover defects on the substrate, improve charge injection from the substrate, protect the photosensitive layer from electrical breakdown, etc. . Materials for the undercoat layer include polyvinyl alcohol and polyvinyl alcohol.
N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, copolymerized nylon, glue, gelatin, and the like are known.

These are each dissolved in a suitable solvent and applied onto the substrate. The film thickness is about 0.2 to 2p.

Charge-generating substances include pyrylium dyes, thiopyrylium dyes, phthalocyanine pigments, anthoanthrone pigments, dibenzpyrenequinone pigments, vilanthrone pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine, and quinocyanine. etc. can be used.

As charge transport substances, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-phenylhydrazino-3-methylidene-9-ditylcarhesol, N,N-diphenylhydrazino-3-methylidene-9 -Ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-1]tin-10-technical II/1-no-mi7panN,N-diphenylhydrazino-3-methylidene-10-ditylphenoxazine , p-diethylaminobenzaldehyde-N,N-diphenylhydrazone,
p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, P-virolidinobenzaldehyde N, N-diphenylhydrazone, 1,3.3
-) Limethylindolenine-〇-aldehyde-N,N-
Hydrazones such as diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-ogisadiazole, 1-phenyl-3- (P-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline, 1-[quinolyl(2)co-3-(p-diethylaminostyryl)-5-
(p-diethylaminophenyl)pyrazoline, 1-
[pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[6-medoxybilidyl(2)]-3-(
p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(3)]-
3-(p-diethylamino/styryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[lepidyl (2
) nee 3-(p-diethylaminostyryl)-5-(p
-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)
-4-Methyl-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)] -3-(α-methyl-p-diethylaminostyryl)-5-(p-diethylamino 2enyl)pyrazoline, 1- Phenyl-3-(
p-diethylaminostyryl)-4-methyl-5-(p
-diethylaminophenyl)pyrazoline, 1-phenyl-3-(α-benzyl-P-diethylaminestyryl)
-5-(p-diethylaminophenyl)pyrazoline, spiropyrazoline and other pyrazolines, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophecol)-4-(
Oxazole compounds such as p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-
Thiazole compounds such as (P-diethylaminostyryl)-6-dinithylaminobenzthiazole, bis(4
Triarylmethane compounds such as -diethylamino-2-methylphenyl)-phenylmethane, 1,1-bis(4-N,N-diethylamino-2-methylphenyl)
Hebutane, l, 1, 2, 2-tetrakis (4-
Polyarylalkanes such as N,N-dimethylamino-2-methylphenyl)ethane and the like can be used.

An example of producing an electrophotographic photoreceptor according to the present invention will be described by taking as an example a case in which a charge transport layer is laminated on a charge generation layer with excessive functional separation.

The above charge generating material is well dispersed 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, an attritor, a roll mill, or the like. This dispersion is applied onto the substrate coated with the undercoat layer and dried to form a coating film of about 0.1 to Ig.

The charge transport layer is formed by dissolving the charge transport material and binder resin in a solvent, dispersing the fluororesin powder, and then coating the charge transport layer on the charge generation layer.

The mixing ratio of the charge transport material and the binder resin is 2:1 to 1:
It is about 2.

When dispersing the fluorine-containing resin powder, use a method such as a homogenizer, ball mill, sand mill, attritor, or roll mill to disperse the fluorine-containing organic solvent and an organic solvent that dissolves the binder in an appropriate ratio. By doing so, a uniform dispersion can be easily obtained.

When applying this solution, a coating method such as a dip coating method, a spray coating method, a spinner coach ink method, a heat coach ink method, a blade kneading method, or a curtain coating method can be used. 200°C1 preferably 20~
150°C range small mark 15 to 1-
Mouth jl h7 size 1. / Ito 1 n
It can be carried out under air blow drying or stationary drying in the time between bags to 9 songs. The thickness of the formed photosensitive layer is 5 to 30
It is about 1000 yen.

[Example Example 1 Polyamide resin (trade name Amiran CM-8000
, Toshi stock system) Apply 5% methanol solution by dipping method,
A thick subbing layer was provided.

Next, 10 parts (parts by weight, same hereinafter) of a disazo pigment having the following structural formula, polyvinyl butyral (trade name BXL, manufactured by FFL Suikagaku Co., Ltd.), and 50 parts of cyclohexanone were mixed in a sand mill using 1 mm diameter glass beads. It was dispersed for 20 hours. 70 to 120 (appropriate) parts of methyl ethyl ketone were added to this dispersion and applied onto the undercoat layer, followed by 10 parts of polymethyl methacrylate and polytetrafluoroethylene powder (trade name: Lubron L-2) as a fluororesin powder. , manufactured by Daikin Cod) was dispersed for 50 hours in a stainless steel ball mill with 40 parts of monochlorobenzene and 15 parts of THF, and the charge transport substance p-diethylaminobenzaldehyde-N-β-/naphthyl-N- was added to the resulting dispersion. 10 parts of phenylhydrazone was dissolved.

This solution was applied onto the charge generation layer and heated to 11°C at 100°C.
A charge transport layer having a thickness of 18 μm was formed by drying with hot air for a period of time. This is designated as sample 1.

Next, prepare a drum coated with the same coating as sample 1 up to the charge generation layer, and apply polymethyl methacrylate 10 on this drum.
5 parts of polytetrafluoroethylene powder was dispersed in a stainless steel ball mill for 50 hours with 40 parts of monochlorobenzene and 15 parts of pencitrifluoride, the same charge transport substance as in sample 1 was added to this dispersion, and the solution was immersed. m applied 1
The sample was dried with hot air at 00° C. for 1 hour to form a charge transport layer having a thickness of 18 mm in the same manner as Sample 1. This is designated as sample 2.

Samples 1 and 2 were imaged on 30,000 sheets using an electrophotographic process consisting of -5.5KV, corona charging, image exposure, dry toner development, toner transfer to plain paper, and cleaning with a urethane rubber blade, and the paper was passed through. We conducted a durability evaluation.

However, regarding Sample 1, the agglomeration of polytetrafluoroethylene powder in the surface layer was so severe that image evaluation could not be performed. Show the results.

Initial durability sample 1 at 23℃ and 55%RH
Large image unevenness □ Unevaluable Sample 2 Good Uniform, high quality, stable image up to 30,000 sheets Durable at 32.5℃, 80% RH Sample 1 □ Sample 2 Uniform, high quality, stable image up to 30,000 sheets Example 2 Similar evaluations were conducted in Example 1 using 10 parts of polyvinylidene fluoride powder instead of polytetrafluoroethylene powder, and p-fluorotoluene instead of the fluorine-containing organic solvent pensitrifluoride. , the same results as in Example 1 were obtained.

Example 3 A 5% methanol solution of polyamide resin (same as above) was applied by dipping onto an aluminum substrate having a diameter of 80 mmφ and a length of 320 mm to form a subbing layer with a thickness of 1JL.

Next, 1-[pyridyl(2)]-3-(p-dimethylaminostyryl)-5-(p-dimethylaminophenyl)
12 parts of pyrazoline and 10 parts of bisphenol A type polycarbonate (trade name: Nipilon S-200, manufactured by Mitsubishi Gas Chemical) were dissolved in a mixed solvent of dioxane and dichloromethane.

This solution was dip-coated onto the above-mentioned undercoat layer and subjected to hot air drying at 100° C. for 1 hour to form a 1-full-thick charge transport layer.

Next, 10 parts of the disazo pigment and 5 parts of polytetrafluoroethylene powder used in Example 1 were mixed with monochlorobenzene/hexafluorobenzene (mixing ratio 7:3) of bisphenol Z type polycarbonate (Mitsubishi Gas Chemical Co., Ltd.). It was added to 100 parts of solution (weight concentration 1.5%) and dispersed in a stainless steel ball mill for 50 hours.

This solution was applied onto the charge transport layer and dried at 100° C. for 20 minutes to form a three-terminal charge generation layer. This is designated as sample 3.

For comparison, a sample without the addition of polytetrafluoroethylene powder was prepared in the same manner as above. This will be referred to as trial #44.

Samples 3 and 4 were attached to an electrophotographic copying machine that has +5.6KV corona charging, image exposure, dry toner development, toner transfer to plain paper, and cleaning process using a urethane rubber blade, and produced 10,000 copies. Paper passing durability evaluation was performed.

Show the results.

Uniform, high-quality, and stable images of up to 310,000 durable samples in an environment of 23°C and 55% RH Abrasion scratches occurred on 42,000 samples High-quality, stable image samples of up to 310,000 durable samples in an environment of 32.5°C and 9096RH Toner fusion with 41,300 sheets Example 4 In Example 3, 10 parts of trifluorochlorinated ethylene resin powder was used instead of polytetratylene, and a mixed solvent of monochlorobenzene/hexafluorobenzene 7:3 was used instead. When the same evaluation as in Example 3 was conducted using a mixed solvent of tetrahydrofuran/1,3-di(trifluoromethyl)benzene (7:3), similar results were obtained.

Example 5 An 80φ x 300 mm aluminum cylinder was used as a base, and a 5% methanol solution of polyamide resin (same as above) was applied by dipping to provide a 1 μ thick subbing layer.

Next, on top of this, a charge generation layer similar to that in Example 1 was applied at a density of 0.15%.
Coated to JL thickness.

Furthermore, on top of this, bisphenol A type polycarbonate 1
0 part dissolved in 60 parts of a mixed solvent of dioxane and dichloromethane, and further dissolved in 10 parts of the charge transport substance used in Example 1, was coated to a thickness of 18 μm by dip coating, and heated at 100°C.
The mixture was dried for 1 hour to form a charge transport layer.

Two of the above samples were prepared, and one of them was further mixed with 2 parts of bisphenol Z-type polycarbonate in dichloromethane/
Benzyl fluoride was dissolved in 30 parts of a 3:l mixed solvent, 1 part of polytetrafluoroethylene powder was added thereto, and the solution was dispersed in a stainless steel ball mill for 50 hours, and the solution was coated to form a protective layer of 1 hiro thick. has been established. This is designated as sample 5.

The remaining one is designated as sample 6.

This sample 5.6 was subjected to an electrophotographic process consisting of -5.5 KV corona charging, image exposure, dry toner development, toner transfer to plain paper, and cleaning with a urethane rubber blade, and 30,000 images were passed through the paper. Durability evaluation was conducted. The results show durability in a 623°C, 55% RH environment. Sample 5 provides uniform, high-quality, stable images up to 30,000 sheets, while sample 6 shows scratches after 10,000 sheets, and toner melts on the surface after 20,000 sheets. It caused damage.

As for durability in a 32.5'C 190% RH environment, Sample 5 produced high quality, uniform and stable images up to 30,000 copies, while Sample 6 had image blurring and blurring after 7,000 copies.

Example 6 In place of bisphenol 2 type polycarbonate in Example 5, styrene-acrylic copolymer (trade name MS-2) was used.
00), dichloromethane/benzyl fluoride 3:1
2-butanone/fluorobenzene7 instead of the mixed solvent of
When a similar evaluation was performed on a sample prepared using a mixed solvent of :3, the same good results as in Example 5 were obtained.

Example 7 An 80φ x 300mm aluminum cylinder was used as a base, and a 5% methanol solution of polyamide resin (same as above) was applied by dipping to provide a 1 square thick subbing layer.

Next, 4 parts of polytetrafluoroethylene powder was added to a solution obtained by adding 1 part of aluminum chloride phthalocyanine, 10 parts of bisphenol Z type polycarbonate, 45 parts of monochlorobenzene, and 15 parts of hexafluorobenzene, and The mixture was dispersed for 50 hours using a manufactured ball mill, and 6 parts of P-diethylaminobenzaldehyde-N-β-naphthyl-N-phenylhydrazone was further dissolved therein.

The thus prepared dispersion was applied onto the undercoat layer to form a photosensitive layer having a thickness of 15 μm.

This photoreceptor will be referred to as Sample 7.

Next, Sample 8 was a photoreceptor prepared using the same method as Sample 7, except that the solvent was replaced with a mixed solvent system of 45 parts of monochlorobenzene and 15 parts of dichloromethane. Sample 9 is a photoreceptor prepared without using a photoreceptor.

Samples 7.8 and 9 photoreceptors were exposed to +5, 6 KV corona charge, one image exposure, dry toner development, plain paper"-(7)
Attached to an electrophotographic copying machine that has a transfer and cleaning process using a urethane rubber blade, and heated at 23°C 155%.
A durability test of 10,000 sheets was conducted in an RH environment. However, regarding Sample 8, the coating film became non-uniform due to aggregation of the polytetrafluoroethylene powder in the photosensitive layer, and the image could not be evaluated.

The evaluation results showed that sample 7 produced uniform and stable images up to 10,000 sheets;
Sample 8 could not be evaluated, Sample 9 had image defects due to toner adhesion to the surface after 3,000 sheets, and blurred images after 7,000 sheets.

[Effects of the Invention] As is known from the above evaluation, the present invention improves the dispersion stability of fluororesin powder and has a remarkable effect on deterioration of electrophotographic characteristics.

Claims (6)

[Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, at least the layer furthest from the substrate is formed using a dispersion containing at least a fluorine-containing resin powder and a fluorine-containing organic solvent. An electrophotographic photoreceptor characterized in that: (2) The fluorine-containing resin powder and the fluorine-containing organic solvent are polymers of ethylene tetrafluoride, ethylene trifluoride chloride, ethylene hexafluoride propylene, vinyl fluoride, vinylidene fluoride, and ethylene difluoride dichloride. and fluororesin powder of copolymer resin powder of tetrafluoroethylene and hexafluoropropylene, bensotrifluoride, benzyl fluoride, n-butyl trifluoroacetate, p-chlorobenzotrifluoride, 1,3 -Claims selected from each of the following fluorine-containing organic solvents: di(trifluoromethyl)benzene, 3,5-di(trifluoromethyl)benzonitride, fluorobenzene, p-fluorotoluene, and hexafluorobenzene. The electrophotographic photoreceptor according to item 1. (3) The content of the fluororesin powder is 1 to 50% by weight based on the weight of the total solids contained in the layer furthest from the conductive substrate. The electrophotographic photoreceptor described above. (4) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer. (5) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer is a single layer containing a charge generating substance. (6) The electrophotographic photoreceptor according to claim 1, wherein the surface resin layer in which fluorine-containing resin powder is dispersed is a protective layer.