JPS6365449A - 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 fluororinated polyarylate. 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 >=1 kinds of fluororinated polyarylates and >=1 kinds of fluororesin powders dispersed into this resin, thus permitting the surface layer to be remarkably enhanced in durability against abrasion and occurrence of scratches due to rubbing by using at least the surface layer containing a fluororesin powder extremely favorably dispersed, to be stable under high humidity and good in cleanability, and capable of always forming high-quality images.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrophotographic photoreceptor with high sensitivity and excellent durability. The present invention relates to an electrophotographic photoreceptor that can be widely used in electrophotographic application fields such as photolithography systems.

[Prior Art] In the field of photoconductive materials for electrophotographic photoreceptors, various types of organic photoconductive materials have been developed in recent years, and in particular, a residue-separated type photoreceptor in which a charge generation layer and a charge transport layer are laminated has already been put into practical use. , installed in copiers and printers.

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

Durability can be roughly divided into two types: durability in terms of electrophotographic physical properties such as sensitivity, residual potential, and charging power, and mechanical durability against abrasion and scratches on the photoreceptor surface due to rubbing. At the technological level, the factor that determines the life of a photoreceptor is often the mechanical durability of the latter.

In addition, the surface layer of the photoreceptor is free from factors that cause image quality deterioration such as adhesion of low-resistance substances due to ozone generated during corona charging under high humidity, or filming and fusion due to poor toner cleaning. Therefore, 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 photoreceptor surface layer as described above, there is known a method of dispersing it in a lubricating powder surface layer such as a fluororesin. This imparts lubricity to the surface layer, improving mechanical durability against wear and scratches, as well as imparting release properties and water repellency, preventing surface deterioration and toner fusion under high humidity conditions. It is also effective for

However, fluororesin powder has problems with dispersibility and agglomeration, making it difficult to form a uniform and smooth film. It was inevitable that I would have it. In addition, binder resins and dispersion aids with good monodispersity often cause deterioration of electrophotographic properties in most cases, and at present no effective one has been found.

[Problems to be Solved by the Invention] The present invention provides an electrophotographic photoreceptor that meets the above requirements.

That is, an object of the present invention is to provide an electrophotographic photoreceptor that has mechanical durability against surface wear and scratches caused by rubbing.

Another object of the present invention is to provide an electrophotographic photoreceptor that is stable and capable of producing high-quality images even under high humidity.

Another object of the present invention is to provide an electrophotographic photoreceptor that has good cleaning properties and does not have toner attached to its surface layer.

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

[Means and effects for solving the problems] The inventors of the present invention have conducted extensive studies in accordance with the above objectives, and as a result, they have dispersed fluorine-based resin powder in one surface layer, and used fluorine atom-containing polyarylate as a dispersion binder. It has been discovered that an electrophotographic photoreceptor that meets the above requirements can be obtained by using the above, and the present invention has been achieved.

In other words, the present invention provides an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, in which at least the layer furthest from the conductive substrate contains one or more fluorine atom-containing polyarylates and a fluorine atom-containing polyarylate. It is characterized by containing L type or two or more types of resin powder.

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 The molecular weight of the resin, the particle size of the powder, etc. are also appropriately selected depending on the specifications of the surface layer to be used.

The fluorine atom-containing polyarylate used in the present invention is
l of the repeating unit represented by the following general formula [I]! J or 2
Linear polymers containing more than one species can be used in combination or as a blend.

Just L/, 11+, Rz, L, XLXL X4
At least one of them represents a fluorine atom and/or a substituent containing at least one fluorine atom. Examples of the substituent containing a fluorine atom include an alkyl group, an aryl group, an alicyclic alkyl group, and an alkoxy group, and R1 and R2 may form a cyclic structure together with the bonded carbon atoms. Furthermore, a halogen atom, a lower alkyl group, an aryl group, etc. may be substituted.

R other than fluorine atoms and substituents containing fluorine atoms
,, R2 is a hydrogen atom, an alkyl group, an aryl group, etc., and R1 and R2 may form a cyclic structure together with the bonded carbon atoms. Furthermore, a halogen atom, a lower alkyl group, an aryl group, etc. may be substituted.

X other than fluorine atoms and substituents containing fluorine atoms
,, X2. X:+, X4 is a hydrogen atom, a halogen atom other than fluorine, an alkyl group, an alicyclic alkyl group, an aryl group, an alkoxy group, and may further have a substituent. n represents the degree of polymerization.

The fluorine atom-containing polyarylate used in the present invention has the structural formula of general formula [I]: RI +R2.

X,,x2. It may be a copolymer with a polyarylate containing no fluorine atom in any of x, X4, in this case,
The fluorine atom-containing portion in the fluorine atom-containing polyarylate is preferably 5% by weight or more, particularly 20% by weight or more.

The fluorine atom-containing polyarylate used in the present invention is produced by a general polyarylate synthesis method such as the terephthalic acid chloride method using one or more diol compounds represented by the following general formula [11], for example. I can do it.

However, at least one of RI, R2, These include aryl groups, alicyclic alkyl groups, alkoxy groups, etc., and R1 and R2 may form a cyclic structure together with the bonded carbon atoms.Also, halogen atoms, lower alkyl groups, aryl groups, etc. !It may be replaced.

R other than fluorine atoms and substituents containing fluorine atoms
,, R2 is a hydrogen atom, an alkyl group, an aryl group, etc., and R and R2 may form a cyclic structure together with the carbon atom to which they are bonded. Furthermore, a halogen atom, a lower alkyl group, an aryl group, etc. may be substituted.

X other than fluorine atoms and substituents containing fluorine atoms
I, XLX3. X4 is a hydrogen atom, a halogen atom other than the metal, an alkyl group, an alicyclic alkyl group, an aryl group,
It is an alkoxy group, etc., and may further have a substituent.

Typical specific examples of the diol compounds used in the present invention are shown below using structural formulas.

When such a fluorine atom-containing polyarylate is used as a binder, the dispersibility of fluororesin powder is much improved compared to when a normal general binder resin is used, and uniform and smooth coating is achieved. A membrane is obtained.

The reason for this is that the fluorine atoms contained as a component of polyarylate have an affinity with the fluorine-based resin powder.
It is thought that it plays a role as a dispersion aid. Therefore, there is no need to add additives such as dispersion, and there is no accompanying adverse effect on electrophotographic properties, such as a decrease in sensitivity, an increase in residual potential, or an increase in memory.

In addition, it maintains the characteristics that polyarylates generally have, such as itching resistance and high hardness, and is extremely effective in improving mechanical durability by dispersing fluororesin powder.

The content of the fluororesin powder dispersed in the surface layer is suitably 2 to 100% by weight based on the fluorine atom-containing polyarylate, particularly preferably 9 to 30% by weight, or less than 2% by weight. If the amount exceeds 100% by weight, the effect of modifying the r-plane layer by dispersing the fluororesin is not sufficient, and on the other hand, the light transmittance decreases and the mobility of optical carriers also decreases.

The structure of the electrophotographic photoreceptor of the present invention can be divided into four types: primary.

1. Substrate/charge-generating layer/charge-transporting layer 2, substrate/charge-transporting layer/charge-generating layer 3, substrate/charge-generating agent + charge-transporting agent (single layer) 4, substrate/photosensitive layer (J:, notes 1 to 1) 3 or yet another form)/
In each case, the protective layer containing the fluorine atom-containing polyarylate and the fluororesin powder is at least the layer furthest away from the substrate.

When manufacturing the electrophotographic photoreceptor of the present invention, the conductive substrate itself may be a conductive material such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, Indium, gold, platinum, etc. can be used, and plastics (for example, carbon black , silver particles, etc.) together with a suitable binder, a substrate in which plastic or paper is impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used.

An undercoat layer having barrier and adhesive functions may 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 undercoat layer has an appropriate thickness of 0.1 to 40 microns, preferably 0.3 to 3 microns.

As charge generating substances, selenium-tellurium, pyrylium, thiopyrylium dyes, phthalocyanine pigments, anthrone pigments, dibenzpyrenequinone pigments, biracitron pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine , 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-10-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, 1,1. :
l-)tumethylindolenine-ω-aldehyde-N,
Hydrazones such as N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, z,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, l- Phenyl-3-(p-diethylaminostyryl)-5-(p
-diethylaminophenyl)pyrazoline, 1-[quinolyl(2)]-3-(p-diethylaminostyryl)-5
-(p-diethylaminophenyl)pyrazoline, 1-[
pyridyl(2)-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline,
1-[5-methoxy-pyridyl(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[piddyl(3)co3-(
p-diethylaminostyryl)-5-(ρ-diethylaminophenyl)pyrazoline, 1-[levigil (z)]
-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(
2) Co-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2)]-3-(α-methyl-p-
diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-phenyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline, niphenyl-3-(
α-benzyl-p-diethylaminostyryl)-5-(
p~diethylaminophenyl) pyrazoline, spiropyrazoline and other pyrazolines, 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxasol,
2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl')-5-(2-chlorophenyl)
Oxazole compounds such as oxazole, thiazole compounds such as 2-(p-diethylaminostyryl)-6-dinithylaminobenzothiazole, and triarylmethane compounds such as bis(4-diethylamino-2-methylphenyl)-phenylmethane. , 1.1-bis(4-N, N
-diethylamino-2-methylphenyl)heptane, 1
, 1°2.2-Tetrakis-(4-N,N-dimethylamino-2-methylphenyl)ethane and the like may be used.

Common dispersion methods for dispersing fluororesin powder are:
That is, a homogenizer, an ultrasonic wave, a ball mill, a vibrating ball mill, a sand mill, an attritor, a roll mill, etc. can be used. Fluorine resin powder is added to the fluorine atom-containing polyarylate 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, a surface layer coating solution containing a fluororesin can be prepared by mixing an appropriate amount of this with a solution of a fluorine atom-containing polyarylate and a charge transport material dissolved in a solvent. can get.

Coating methods include dip coating method, spray coating method, spinner coating method, beat coating method,
Mayer coating method, plate coating method,
This can be carried out using a coating method such as 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 ventilation.

[Example] The present invention will be specifically described below with reference to Examples.

Example 1 An aluminum cylinder of 80 mφ x 350 m was used as a conductive substrate, and a 5% methanol solution of polyamide resin (trade name: Amilan 0M-8000, manufactured by Toshi) was applied to it by dipping method, and then heated under 1 lN. A pull layer was provided.

Next, 10 parts (parts by weight, the same shall apply hereinafter) of a disazo pigment having the following structural formula, polyvinyl butyral (trade name: Esleuk B)
XL, manufactured by Blockchain Chemical ■) 6 parts and 1 cyclohexanone
00 parts by a cytomill device using 1φ glass beads.
Dispersed for 0 hours.

Add 50 to 100 (appropriate) parts of tetrahydrofuran to the obtained dispersion, spread it on the undercoat layer, and heat it at 100°C55.
After drying for a few minutes, a charge generation layer having a thickness of 0.15 JL was formed.

Next, as the fluorine atom-containing polyarylate, one with the following structural formula was used, and as the fluorine-based resin powder, polytetrafluoroethylene resin powder (trade name Nilbron L-2, manufactured by Daikin Industries) was used.
.

ntalo0 Hydrazone compounds having the following structural formulas were prepared as charge transport substances.

First, 20 parts of the above polyarylate was mixed with 4 parts of cyclohexanone.
0 parts of Tetra and 1 to 92 parts of Tetra, 5 parts of the above tetrafluoroethylene resin powder was added thereto, dispersed in a stainless steel ball mill for 50 hours, and further dissolved in dichloromethane 2
A charge transport F3 coating solution was prepared by adding 0 parts of the hydrazone compound and 20 i'll of the above hydrazone compound. This solution was coated on the charge generation layer and dried with hot air at 100°C for 1 hour to form a 18μ
A charge transport layer having a thickness of L was formed. 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 bisphenol A type polyarylate (trade name: U-100 Sumitomo Chemical Ezu Co., Ltd.) was used as the binder for the cargo transport layer. Created. This will be referred to as photoreceptor 2.

The two photoconductors created in this way were transferred to Ichihara's copying machine (
NP-3525 (manufactured by Canon Inc.), and image evaluation and durability evaluation were performed. The results are shown in Table 1.

As is clear from Table 1, the photoreceptor l of the present invention has high image quality due to the good dispersibility of the tetrafluoroethylene resin powder, and also has less wear due to long-term use. Photoconductor 2 has poor dispersibility of the polytetrafluoroethylene resin powder, and the surface of the photoconductor has aggregated particles or protruding irregularities, resulting in very rough images. When a durability test was conducted in the surface condition, there was a problem that toner easily adhered to the surface due to poor cleaning.

Next, the above sample after durability use was further heated at high temperature and humidity (32
, 5℃, 90% RH), the durability test was continued.
Photoreceptor 1 could stably produce high-quality images up to 200,000 sheets, whereas photoreceptor 2 had white spots and image deletion after 6000&rrO.

This is thought to be due to the occurrence of pinholes due to the presence of aggregates of the polytetrafluoroethylene resin powder and low resistance substances accumulated in the uneven portions of the surface.

Example 2 In the same manner as in Example 1, l#L was placed on an aluminum cylinder.
A thick polyamide resin subbing layer was provided.

Next, 15 parts of a pyrazoline compound having the following structural formula and 10 parts of bisphenol 2 type polycarbonate (manufactured by Mitsubishi Gas Chemical) were dissolved in 50 parts of monochlorobenzene and 10 parts of dichloroethane, and this solution was dip-coated on the undercoat layer, 100'
After drying for 11 hours, a charge transport layer having a thickness of 15 layers was formed.

Next, 2 parts of the bisazo pigment having the following structural formula and 4 parts of the Teflon powder used in Example 1 were added to 100 parts of a 10% monochlorobenzene solution of a fluorine-containing polyarylate having the following structural formula, and the mixture was milled in a styrene-free ball mill for 50 parts. Spread out time.

Seven parts of the hydrazone compound used in the charge transport layer was dissolved in the resulting dispersion to obtain a charge generation layer coating solution. This liquid was applied on top of the cylinder to form a charge generation layer with a thickness of 4 ml. This will be referred to as a photoreceptor 3.

On the other hand, for comparison, a photoreceptor was prepared in the same manner as in Example 2 except that bisphenol z5 polyarylate was used as the binder in 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 O-transfer charging, and the same evaluation as in Example 1 was carried out. 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 X was formed on an aluminum cylinder.

Next, 1 part of aluminum microlide phthalocyanine and Example 1
10 parts of the fluorine-containing polyarylate used in Example 1 and 4 parts of polyvinylidene fluoride were dispersed together with 45 parts of monochlorobenzene and 15 parts of tetrahydrofuran in a stainless steel ball mill for 50 hours, and 10 parts of the hydrazone compound used in Example 1 was dispersed in a stainless steel ball mill. A photosensitive layer coating solution was prepared by dissolving the following. This was applied by dip coating onto the two subbing layers and dried at 100°C for 1 hour to form a photosensitive layer with a thickness of 12p. This is the photoreceptor 5
shall be.

On the other hand, for comparison, Polycarbo A was used as a binder for the photosensitive layer.
J! ! A photoreceptor was prepared in the same manner as in Example 3, except that a photoreceptor (trade name: U-100 manufactured by Sumitomo Chemical Industries, Ltd.) was used. This will be referred to as the photoreceptor 6.

Example 4 In the same manner as in Example 1, an undercoat layer of polyamide resin having a thickness of 1/2 inch was formed on an aluminum cylinder.

Next, 1 part of aluminolide phthalocyanine and 10 parts of bisphenol Z-type car realylate were dispersed for 50 hours in a stainless steel ball mill with 45 parts of monochlorobenzene and 15 parts of tetrahydrofuran. It was dissolved to prepare a photosensitive layer coating solution. This was coated on the undercoat layer by immersion vL, and 1
After drying at 00°C for 1 hour, a photosensitive layer having a thickness of 12 l was formed.

Next, 10 parts of the fluorine-containing polyarylate used in Example 2 and 5 parts of Teflon powder were dispersed together with 30 parts of monochlorobenzene and 40 parts of tetrahydrofuran in a paint shaker for 5 hours, and the resulting dispersion was applied onto the photosensitive layer. A protective layer having a thickness of 2JL was provided by overcoating. 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 bisphenol Z-type polyarylate used in the photosensitive layer was used as the protective layer binder. This will be referred to as a photoreceptor 8.

These photoreceptors were evaluated in the same manner as described in Example 1. The results are shown in Table 3.

As is clear from Table 3, the photoreceptor of the present invention has a surface layer in which the fluorine resin one-finger powder is extremely well dispersed.
It can maintain high quality +ifi quality even after long-term durable use.

[Effects of the Invention] In the electrophotographic photoreceptor of the present invention, the fluororesin powder is extremely well dispersed at least in the surface layer.
It exhibits excellent durability against abrasion and scratches caused by rubbing, is stable even under high humidity, has good cleaning properties, and does not cause toner adhesion, surface coating unevenness, or pinholes. First, there is no accumulation of residual potential, so high-quality images can always be provided.

Claims (1)

[Scope of Claims] (1) In an electrophotographic photoreceptor having a photosensitive layer on a conductive substrate, at least the layer furthest away from the conductive substrate is
An electrophotographic photoreceptor comprising one or more fluorine atom-containing polyarylates and one or more fluororesin powders: (2) The fluororesin powder is Tetrafluoroethylene resin,
Claim 1, which is a powder selected from ethylene trifluoride chloride resin, ethylene hexafluoride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and copolymers thereof. Electrophotographic photoreceptor according to item 1: (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 is made of a fluorine atom-containing polyarylate. species or two
(4) The photosensitive layer contains a charge-generating substance and a charge-transporting substance. The electrophotographic photoreceptor according to claim 1, which comprises a single layer: (5) The ratio of the fluororesin powder to the fluorine atom-containing polyarylate is 2 to 100% by weight. Electrophotographic photoreceptor according to item 1: (6) The layer containing the fluorine atom-containing polyarylate and fluororesin powder and which is furthest away from the conductive substrate is a protective layer formed on the photosensitive layer. Electrophotographic photoreceptor according to claim 1: