JPS6365450A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance durability against abrasion and occurrence of scratches on the surface of an electrophotographic sensitive body due to rubbing by using the surface layer containing a fluororesin powder dispersed into a dispersion binder of a fluorinated polymer. CONSTITUTION:The electrophotographic sensitive body is provided with a conductive substrate and a photosensitive layer formed on it and the surface layer located farthest from the substrate containing the fluororinated polymer and the fluororesin powders dispersed into this resin. The fluorinated polymer to be used here is a polymer or copolymer having structural units derived from a polymerizable monomer having a fluorinated group on the side chain, and the fluororesin powder to be used here is one or a combination properly selected from the powders of the following polymers: tetrafluoroethylene, trifluorochloroethylene, difluorodichloroethylene, and hexafluoroethylenepropylene resins, polyvinyl fluoride, polyvinylidene fluoride, and the copolymers of the monomers of these polymers.

Description

[Detailed description of the invention] [Industrial use! ? ] The present invention relates to an electrophotographic photoreceptor with high sensitivity and excellent durability, and more specifically, it can be widely used in electrophotographic application fields such as electrophotographic copying machines, laser beam printers, CRT printers, and electrophotographic plate making systems. Related to electrophotographic photoreceptors.

[Prior Art] In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photoreceptors, and in particular 'I! A-type photoreceptors with a charge generation layer and a charge transport layer have already been put into practical use and are used in copiers and printers.

However, one major drawback of these photoreceptors has been that they generally have low durability.

Its durability can be roughly divided into two categories: sensitivity, residual potential, durability ratio of electrophotographic physical properties such as band 11tfl, and mechanical durability such as abrasion and scratches on the photoreceptor surface due to rubbing. At the current state of the art, the main factor determining the life of a photoreceptor is often the mechanical durability of the latter.

In addition, the surface layer of the photoreceptor has factors that cause image quality deterioration such as adhesion of low-resistance substances due to ozone generated during corona charging in a high humidity environment, or filming and fusion due to poor toner cleaning. In addition to the above-mentioned mechanical durability, mold releasability against various deposits is also required.

As a method for satisfying the characteristics required for the surface layer of a photoreceptor as described above, there is a known method of dispersing lubricating powder such as fluororesin in the surface layer. This provides lubricity to the surface layer.

In addition to improving mechanical durability against wear and scratches, it also improves mold releasability and water repellency, making it effective in preventing surface deterioration and toner fusion in high-humidity environments.

However, fluororesin powder has problems with dispersibility and agglomeration, making it difficult to form a uniform and smooth film, so the resulting surface layer avoids image defects such as image unevenness and pinholes. I couldn't.

Furthermore, binder resins or dispersion aids with good dispersibility often cause deterioration of electrophotographic properties in most cases, and it is difficult to find an effective one at present.

[Problems to be Solved by the Invention] Another object of the present invention is to provide an electrophotographic photoreceptor that has mechanical durability against surface abrasion and scratches caused by am.

Another object of the present invention is to provide an electrophotographic photoreceptor that can stably produce high-quality images even in a high-temperature environment.

Another object of the present invention is to provide an electrophotographic photoreceptor that is free from coating unevenness and pinholes on its surface, and which does not accumulate residual potential during repeated electrophotographic processes and can always produce high-quality images. .

[Chief actors and actions to solve the problem] As a result of extensive studies in line with the above objectives, the inventors of the present invention dispersed fluorine-based resin powder in the surface layer, and the dispersed binder contained fluorine atoms. The present invention was completed based on the discovery that an electrophotographic photoreceptor that meets the above requirements can be obtained by using a polymer.

That is, the present invention is characterized in that, in an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, at least the elbow furthest away from the substrate contains a fluorine atom-containing polymer and a fluororesin powder.

However, the fluorine atom-containing polymer referred to herein refers to a polymer or copolymer having as a constituent component a polymerizable monomer having a fluorine atom substituent in its side chain.

The fluororesin powder used in the present invention includes tetrafluoroethylene resin, trifluorochloride ethylene resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene dichloride difluoride resin, and One or more types of copolymer resins are appropriately selected from the powders of copolymer resins, and the molecular weight of the resin, particle size of the powder, etc. can be appropriately selected depending on the specifications of the surface layer to be used.

Further, the polymerizable monomer having a fluorine atom substituent in the side chain used in the present invention is particularly preferably a compound represented by the following general formula.

(In the above formula, R1 is a hydrogen atom or a methyl group, and R2 is an alkyl group or an aryl group containing a fluorine atom.) Specific examples of the compounds represented by the general formulas [I] and [I[] are shown below.

υ (n = number of 4 to 12) The polymer or copolymer having one of the above polymerizable monomers as a constituent component used in the present invention can be obtained by homopolymerization or copolymerization of two or more of the polymerizable monomers. It can be obtained by polymerization, and further by copolymerization of one or more of the polymerizable at-isomers and other vinyl compounds.

The polymerization method is solution polymerization method, S1! ir1 polymerization method,
Radical polymerization such as bulk polymerization and ionic polymerization can be applied, but radical polymerization by solution polymerization is simple and preferred.

Other vinyl compounds to be copolymerized may be those that are copolymerizable with a polymerizable monomer having a fluorine atom substituent in the side chain, but in particular, methacrylate ester acids, acrylic esters, and styrene compounds may be used. etc. are preferable.

In this copolymer, the content of the repeating unit based on the polymerizable monomer having a fluorine atom substituent in the side chain is 5
Must be at least % by weight.

In particular, it is preferably in the range of 10 to 70% by weight, and if it is less than 5% by weight, the effects of the present invention cannot be obtained.The molecular weight of the obtained polymer is a weight average molecular weight Mw of to, ooo to i,
ooo, ooo especially 10[1,000~600,
A range of 000 is preferred.

When such a fluorine atom polymer is used as a binder,
The dispersibility of the fluororesin powder is much improved compared to when a normal binder resin is used, and a uniform and balanced coating film can be obtained. The reason for this is thought to be that the fluorine atom contained as a component of the polymer has an affinity with the fluororesin powder, and thus functions as a dispersion aid. However, in the present invention, since there is no need to add additives such as dispersants, the accompanying adverse effects on electrophotographic properties, such as a decrease in sensitivity, an increase in residual potential, and an increase in memory, do not occur at all. do not have.

In the present invention, the content of the fluororesin powder dispersed in the surface layer is 2 to 100% by weight based on the fluorine atom-containing polymer.
is appropriate, and particularly preferably 5 to 30% by weight. If the content is less than 2% by weight, the effect of modifying the surface layer by dispersing the fluororesin will not be sufficient, while if it exceeds 100% by weight, the light transmittance will decrease and the mobility of the optical carrier will also decrease.

The a composition of the electrophotographic photoreceptor of the present invention can be divided into the following four types.

1. Conductive substrate/charge generation KJ/charge transport layer 2. Conductive substrate/charge transport layer/charge generation layer 3. Conductive substrate/charge generation material + electrotransport material (single layer) 4. Conductive substrate/photosensitive Layer (1 to 3 above or another form)/protective layer In each case, the fluorine atom-containing polymer and fluororesin powder are contained at least in the layer furthest from the conductive substrate. be.

When manufacturing the electrophotographic photoreceptor of the present invention, the conductive substrate itself is conductive, such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, and indium. , gold, platinum, etc. can be used, and in addition, plastics having a layer formed by vacuum deposition of aluminum, aluminum alloy, indium oxide, tin oxide, indium oxide-tin oxide alloy, etc. (for example, carbon black, silver It is possible to use a substrate in which a plastic is coated with particles (such as particles, etc.) together with a suitable binder, a substrate in which plastic or paper is impregnated with conductive particles, a plastic having a conductive polymer, and the like.

An undercoat layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. The subbing layer is casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed from acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is suitably 0.1 micron to 40 micron, preferably 0.3 micron to 3 micron.

As charge-generating substances, selenium-tellurium, trillium, thiopyrylium dyes, phthalocyanine pigments, anthrone pigments, dibenzpyrenequinone pigments, vilanthrone pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, asymmetric Quinocyanin, quinocyanine, etc. can be used.

As the charge transport substance, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-1O-ethylphenothiazine, N,N -diphenylhydrazino-3-methylidene-
10-Ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N
-Phenylhydrazone, p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1. moss 3-trimethylindolenine-ω-aldehyde-N,N-diphenylhydrazone, p-diethylhenzaldehyde 3-
Hydrazones such as methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)
-1,3,4-oxadiazole, l-phenyl-3-
(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-[quinoline (2)]
-3-(P-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(p-diethylaminostyryl)
-5-(p-diethylaminophenyl)pyrazoline, t
-C5-methoxy-pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(3)]-3-(
p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, ■-[Lepidil (2)]
-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline,! −[pyridyl(
2)] -3-(p-diethylaminostyryl)-4-
Methyl-5-(p-diethylaminophenyl)pyrazoline, l-[pyridyl(2)]-3-(α-methyl-p
-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-phenyl-3-
(α-benzyl-p-diethylaminostyryl)-5-
Pyrazolines such as (p-diethylaminophenyl)pyrazoline and spiropyrazoline, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, 2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl)- 5-(2-chlorophenyl)
Oxazole compounds such as oxazole, thiazole compounds such as 2-(P-diethylaminostyryl)-6-dinithylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane. , l, 1-bis(4-N, N
-diethylamino-2-methylphenyl)hebutane, 1
．． Polyarylalkanes such as 1,2.2-tetrakis-(4-N,N-dimethylamino-2-methylphenyl)ethane and the like can be used.

As the fluororesin powder dispersion method, general dispersion means such as a homogenizer, ultrasonic wave, ball mill, vibrating ball mill, Santo mill, attritor, roll mill, etc. can be used. Fluorine resin powder is added to a fluorine atom-containing polymer dissolved in a suitable solvent, and then dispersed by the above-mentioned dispersion method. For example, if the charge transport layer is a surface layer, an appropriate amount of this is mixed into a solution in which a fluorine atom-containing polymer and a charge transport substance are dissolved in a solvent.

A surface layer coating liquid containing a fluororesin is obtained.

Coating methods include dip coating method, spray coating method, spinner coating method, beat coating method,
This can be carried out using a coating method such as a Mayer coating method, a plate coating method, a roller coating method, or a curtain coating method. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at 30 to 200° C. for a period of 5 minutes to 2 hours, either stationary or with air blowing.

[Example] Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 A J Reminium cylinder of 80 mm diameter x 35011 mm was used as a base, and polyamide resin (trade name: Amilan CM) was applied to this cylinder.
-8000. A 5% methanol solution (manufactured by Toshi Co., Ltd.) was applied by dipping to form an undercoat layer with a thickness of 1 mm.

Next, 10 parts of a disazo pigment having the following structural formula (6 parts by weight (trade name: Eslec BXL, Building Block Chemical Co., Ltd., 1 g)) and 100 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using lφ glass beads.

Add 50 to 100% of tetrahydrofuran (as appropriate) to this dispersion.
The mixture was coated on the undercoat layer and dried at 100° C. for 5 minutes to form a charge generation layer with a thickness of 0.151 L.

Next, as a fluorine atom-containing polymer, the following structural formula (10) is used.
copolymer and tetrafluoroethylene resin powder (trade name Nilbron L-2, Daikin Industries*) as a fluororesin powder.
A hydrazone compound having the following structural formula (11) was prepared as a charge transport material.

First, 20 parts of the above copolymer was dissolved in 100 parts of cyclohexanone, 5 parts of the above tetrafluoroethylene resin powder was added thereto, and dispersed in a stainless steel ball mill for 50 hours, and then 20 all of dichloroethane was added to transport charge. A layer coating solution was prepared. This solution was coated on the charge generation layer, and
A charge transport layer having a thickness of 18 IL was formed by drying with hot air at 0° C. for 1 hour. This is referred to as photoreceptor l.

On the other hand, a photoreceptor was prepared in the same manner as in Example 1 except that a homopolymer of polymethyl methacrylate was used as the binder for the charge transport layer. This will be referred to as photoreceptor 2.

The photoconductor produced as described above was used as a commercially available copy m (kiv).
NP-3525 (manufactured by /N Co., Ltd.) for image evaluation,
Durability evaluation was conducted. The results are shown in Table 1.

As is clear from Table 1, the photoreceptor 1 of the present invention has:

1 because the polytetrafluoroethylene powder has good dispersibility.
The image quality is high and there is little wear due to long-term use. On the other hand, photoreceptor 2 of Comparative Example has poor dispersibility of the tetrafluoroethylene resin powder, resulting in aggregated particles or protruding irregularities on the surface of the photoreceptor. This results in a very grainy image. Further, if the toner is used for a long period of time in such a surface condition, a problem arises in that toner tends to adhere to the surface due to poor cleaning.

Next, after the above-mentioned durable use, the above-mentioned sample was further heated and
When durability tests were continued in an environment (32.5°C, 90% RH), photoconductor 1 produced stable high-quality images up to 200,000 sheets, while photoconductor 2 produced stable images up to 6,000 sheets. White spots and image blurring occurred from the front and back.

This is due to the occurrence of pinholes due to the presence of aggregates of 2-tetrafluoroethylene resin and the presence of riNl on the uneven surface.
This is thought to be due to the low resistance material.

Example 2 In the same manner as in Example 1, a 1 part thick subbing layer made of polyamide resin was formed on an aluminum cylinder.

Next, 15 parts of the pyrazoline compound m of the following structural formula and 10 parts of polymethyl methacrylate were added to 50 parts of monochlorobenzene,
Dissolved in 10 parts of dichloroethane, soaked this solution on the above-mentioned undercoat layer, and heated at 100°C.

It was dried for 1 hour to form a charge transport layer with a final thickness of 15 cm.

Next, 2 parts of the bisazo content of the following structural formula and 4 parts of the Teflon powder used in Example 1 were added.

A fluorine atom-containing polymer having the following structural formula was added to 100 parts of a 10% monochlorobenzene solution and dispersed in a styrene-less ball mill for 50 hours.

a/b = 278 In the obtained dispersion, 7flJ of the hydrazone compound used in the charge transport layer was dissolved to prepare a coating liquid for the charge generation layer. This liquid was applied onto the cylinder to form a charge generating layer having a final thickness of 4. This will be referred to as photoreceptor 3.

On the other hand, for comparison, a photoreceptor was prepared in the same manner as in Example 2, except that polymethyl methacrylate was used as the binder for the charge generation layer. This will be referred to as a photoreceptor 4.

These photoreceptors were installed in a copying machine that uses corona charging, negative toner development, and transfer charging, and were evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 3 In the same manner as in Example 1, an undercoat layer of polyamide resin having a thickness of 1 liter was formed on an aluminum cylinder.

Next, 1 part of aluminum microlide phthalocyanine and Example 1
10 parts of the fluorine atom-containing polymer and 4 parts of vinylidene fluoride used in 1 were dispersed in a stainless steel ball mill for 50 hours with 45 parts of monochlorobenzene and 15 parts of tetrahydrofuran, and 10 parts of a hydrazone compound of the following structural formula was dissolved therein. The photosensitive layer coating solution was subjected to II conditioning.

This coating solution was dip-coated onto the undercoat layer, and the coating solution was applied at 100°C for 1 hour.
After drying for an hour, a photosensitive layer having a final thickness of 12 hours was provided.

This will be referred to as the photoreceptor 5.

On the other hand, for comparison, a photoreceptor was prepared in the same manner as in Example 3 except that polymethyl methacrylate was used as the photosensitive layer binder. This will be referred to as the photoreceptor 6.

Example 4 In the same manner as in Example 1, a subbing layer of polyamide resin having a thickness of 1 pL was formed on an aluminum cylinder.

Next, 1 part of aluminum microlide phthalocyanine and polyethyl methacrylate/poly n-butyl methacrylate (6
/4) 10 parts of copolymer, 45 parts of monochlorobenzene,
The mixture was dispersed for 50 hours in a stainless steel ball mill with 15ffi of tetrahydrofuran, and 10 parts of a hydrazone compound having the following structural formula was dissolved therein to prepare a photosensitive FB coating liquid iA.

This coating solution was dip-coated onto the undercoat layer, and the coating solution was applied at 100°C for 1 hour.
After drying for hours, a photosensitive layer with a thickness of 12 g was formed.

Next, 10 parts of the fluorine atom-containing polymer used in Example 2 and 5 parts of Teflon powder were dispersed together with 70 parts of monochlorobenzene in a paint shaker for 5 hours, and the resulting liquid was applied onto the photosensitive layer, A protective layer having a final thickness of 2 was formed. This will be referred to as photoreceptor 7.

For comparison, a photoreceptor was prepared in the same manner as in Example 4, except that the polyethyl methacrylate/poly n-butyl methacrylate copolymer used in the photosensitive layer was used as the binder for the protective layer. This will be referred to as a photoreceptor 8.

These photoreceptors were evaluated in the same manner as described in Example 1.2. The results are shown in Table 3.

As is clear from the above table, the photoreceptor of the present invention has a surface layer in which the fluororesin powder is extremely well dispersed, so that it is possible to maintain high image quality even after long-term use.

[Effects of the Invention] Since the electrophotographic photoreceptor of the present invention has a surface layer in which fluororesin powder is extremely well dispersed, there is no coating film unevenness or pinholes, and the surface does not suffer from rubbing even after long-term use. It has sufficient mechanical durability against wear and scratches, is stable even in high-temperature environments, and can provide high-quality images.

Claims (6)

[Claims] (1) An electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, in which at least the layer furthest from the substrate contains a fluorine atom-containing polymer and a fluorine resin powder. Photoreceptor: (2) The fluororesin powder is a tetrafluoroethylene resin, a trifluorochloroethylene resin, a hexafluoroethylene propylene resin, a vinyl fluoride resin, a vinylidene fluoride resin,
The electrophotographic photoreceptor according to claim 1, which is a powder selected from a difluoride dichloride ethylene resin and a copolymer thereof: (3) The photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, and the charge generation layer and/or the charge transport layer contains a fluorine atom-containing polymer and a fluororesin powder. An electrophotographic photoreceptor according to claim 1: (4) The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer is a single layer containing a charge-generating substance and a charge-transporting substance: (5) The electrophotographic photoreceptor according to claim 1, wherein the ratio of the fluororesin powder to the fluorine atom-containing polymer is 2 to 100% by weight: (6) The electrophotographic photosensitive material according to claim 1, wherein the layer containing the fluorine atom-containing polymer and the fluorine-based resin powder and which is the most distant from the substrate is a protective layer formed on the photosensitive layer. body: