JPH03293672A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent occurrence of solvent cracks on the surface by specifying the yielding elongation to breaking elongation ratio of the binder resin of a layer containing an electric charge generating material and/or a surface layer at room temperature at the time of forming the layer. CONSTITUTION:The yielding elongation to breaking elongation ratio of the binder resin of the layer containing the charge transfer material and/or the surface layer at room temperature at the time of forming the layer is controlled in the range of 1-10. In order to enhance the extensibility of the polymer film a solvent having a dipole moment of <=1.7D is used for coating the binder resin, thus permitting occurrence of the solvent cracks in the charge transfer layer and/or the surface layer to be prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is an electrophotographic photosensitive material that can be widely used in electrophotographic application fields such as electrophotographic copying machines, laser beam printers, facsimile machines, CRT printers, and electrophotographic plate making systems. Regarding the body.

[Conventional technology]

Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known so far.

On the other hand, since it was discovered that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed. For example, organic photoconductive polymers such as polyvinylcarbazole, polyvinylanthracene, carbazole, anthracene, pyrazolines, oxadiazoles,
hydrazones.

Organic pigments and dyes such as low-molecular organic photoconductors such as polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, polyurethane pigments, indigo dyes, thioindigo dyes, and square link acid methine dyes. It has been known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the range of options for selecting compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. Photoconductive organic pigments and dyes have been proposed. for example.

U.S. Patent No. 4123270, U.S. Patent No. 4247614,
Same No. 4251613, Same No. 4251614, Same No. 4
No. 256821, No. 4260672, No. 4268
No. 596, No. 4278747, No. 4293628
Electrophotographic photoreceptors are known that use a photoconductive disazo pigment as a charge generation substance in a photosensitive layer that is functionally separated into a charge generation layer and a charge transport layer, as disclosed in the above specification.

Electrophotographic photoreceptors using such organic photoconductors can be produced by coating by appropriately selecting pine paste, making it possible to provide photoreceptors with extremely high productivity and low cost. It has the advantage that the sensitive wavelength range can be freely controlled by selection.

Conventionally, ? is a resin commonly used as a binder for making up this type of electrophotographic photoreceptor? Examples include polyethylene resin, polystyrene resin, polybutadiene resin, fluororesin, polyester resin, polycarbonate resin, epoxy resin, polyurethane resin, alkyd resin, acrylic resin, and silicone resin.

[Problem to be solved by the invention]

However, due to poor adhesion between the charge transport layer and the layers below it, the film formation properties of the charge transport layer deteriorated, causing sweat and oil from the human body to form on the surface of the photosensitive layer.

There is a problem in that the charge transport layer tends to crack due to the adhesion of monomers that act as plasticizers, etc., and a method to solve this problem is to blend a binder resin (Japanese Patent Laid-Open No. 61-62040).
) have not yet been proposed, and there are inconveniences such as restrictions on lubricating oil and rubber parts for mechanical parts that can be used near the photoreceptor, and the need to be careful when handling the photoreceptor. Ta.

Therefore, an object of the present invention is to provide an electrophotographic photoreceptor in which solvent cracks do not occur on the surface.

[Means and effects for solving the problems] That is, the present invention provides (1) an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on an electrically conductive support; /or the binder resin of the surface layer is
An electrophotographic photoreceptor comprising a polymer having a ratio of elongation at break to yield elongation at room temperature when a coating is formed in a range of greater than 1 and less than 10; (2) The electrophotographic photoreceptor of (2), characterized in that the solvent or a mixed solvent of two or more solvents has a dipole moment of 1.7D or less; 0.2~51Rn
2. The electrophotographic photoreceptor according to claim 1, wherein the intermediate layer is a film obtained by curing a composition containing a polyamide resin or a thermosetting resin. This is an electrophotographic photoreceptor.

According to the present invention, the polymer film formed by the binder resin used in the layer containing the charge transport substance and/or the surface layer is a polymer film having a yield point in a tensile strength test, and the yield elongation of the polymer film is A polymer coating that stretches within a range of 1 to 10 at room temperature, with a ratio of elongation at break to It is. Further, in order to obtain extensibility of the polymer film, a solvent having a dipole moment of 1°7D or less is used as a coating solvent for the binder resin to form the film, thereby preventing the occurrence of solvent oxidation. In addition, in order to relieve residual stress between the conductive support and the charge transport layer, an intermediate layer of 0.2 to 5 layers, preferably 0.5 to 2 layers, is provided to remove the solvent in the charge transport layer. It provides resistance against clubbing. In addition, in order to enhance the effect of relieving residual stress, the intermediate layer /
A composition containing an IJ amide resin or a thermosetting resin was cured.

The electrophotographic photoreceptor of the present invention may be a single-layer photoreceptor that has both a charge generation function and a charge transport function, or a laminated photoreceptor that has separate layers for each function. Furthermore, a surface layer may be provided on the photosensitive layer to improve the surface properties of the photoreceptor.

In addition, K is added to relieve the stress during film formation of the charge transport layer.

An intermediate layer may be formed between the conductive support and the charge transport layer.

The conductive support for this photoreceptor is metal such as aluminum, copper, or nickel, or aluminum or nickel on a plastic sheet.

It is possible to use a material coated with a conductive substance such as chromium by vapor deposition, spackling, etc. to make it conductive, or a material made of glass, plastic, cloth, paper, etc. that has been subjected to conductive treatment. Examples of charge generating materials include phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, -
e-Rylene pigments, indico dyes, etc. can be used. In addition, the binder resin used for the charge generation layer is polystyrene, ? Vinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl acetal, alkyd resin, acrylic resin, polyacrylonitrile resin, polycarbonate resin, polyamide resin, ketone resin.

Known resins such as polyacrylamide resin, butyral resin, polyester resin, polyurethane resin, epoxy resin, and phenol resin can be used.

Charge transport substances in the charge transport layer include electron transport substances and hole transport substances, and examples of electron transport substances include chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, and 2.4.7-dolinitro9.
-fluoreno/, 2゜4.5.7-tetranitro-9-
Fluorenone.

2.4.7-dolinitro 9-dicyanomethylenefluorenone, 2,4,5.7-tetranitroxanthone, 2
, 4.9-) There are electron-withdrawing substances such as linitrothioxanthone, and polymerization of these electron-withdrawing substances.

As a hole transport substance, pyrene, N-ethylcarba:/
'-ru, N-inpropylcarbaso A/, N
-Methyl-N-phenylhydrazino-3-methylylene-
9-Ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N
-Diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N.

N-diphenylhydrazino-3-methylidene-10-ethylphenoxacin, P-diethylaminobenzaldehyde-N,N-diphenylhydrazone, P-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, P-pyrrolituno Benzaldehyde-N
, N-diphenylhydrazone, N, N'-diphenyl-N, N'-bis(methylphenyl)benzidine, N, N'-diphenyl-N, N'-bis(
ethylphenyl)benzidine, N,N'-diphenyl-N, N'-bis(propylphenyl)benzidine, N,N'-diphenyl-N.

N'-bis(butylphenyl)-benzidine, N.

N/-His(isoglobylphenyl)-benzidine, N
, N'-diphenyl-N, N'-bis(secondary butylphenyl)-benzidine, N,N'-diphenyl-N, N'-bis(tertiary butylphenyl)-benzidine and N,N'- Diphenyl-N, N'
-bis(chlorophenyl)-benzidine isotonic al.

Further, as the binder resin used for the charge transport layer and/or the surface layer, polycargenate, acrylic resin,
Known materials such as polyamide and/or lyacrylamide are used, and polycarbonate resin is preferred. Particularly preferably, a polycarbonate resin which is a polyarylate, more specifically a polymer compound containing bisphenol A as a constitutional unit, and a polymer compound containing bisphenol 2 as a constitutional unit are used in the charge transport layer and/or the surface layer. It has particularly excellent mechanical properties as a binder resin.

The charge generation layer and the charge transport layer can be formed by applying a coating solution in which the above-mentioned substance is ground or dissolved together with a binder resin in a solvent, and then dried. Examples of the solvent include known organic solvents, but the charge transport layer and/or
Alternatively, the solvent used for the surface layer is preferably one with a dipole moment of 1.7D or less, such as dioxane, tetrahydrofuran, monochlorobenzene, dichloromethane, trichloromethane, 1,1.1-trichloroethane, 1.
1,2-trichloroethane, 1,1-dichloroethylene, trichloroethane, methanol, ethanol, benzene, toluene, xylene, etc. are used, and particularly preferred are cyclic ether compounds such as dioxane and tetrahydro-7rane, whose dipole moment is 1.7D. The following,
and aromatic hydrocarbons such as benzene, toluene, and xylene whose dipole moment is 1.7D or less. These solvents may be used alone, but
It is sufficient that the coating solvent is substantially composed of a solvent with a dipole moment of 1.7D or less, and the dipole moment is 1.7D or less.
When using a mixture of the following solvents and a solvent exceeding 1.7D, it is preferable that the amount of the solvent having a dipole moment of 1.7D or less is 50 weight cents or more. The intermediate layer for relieving residual stress in the charge transport layer is made of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer I-rivinyl petyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610. copolymer) (nylon, alkoxymethylated nylon, etc.), polyurethane gelatin, aluminum oxide, EVA
It can be formed from various elastomers, such as styrene-butadiene rubber, which do not adversely affect the electrophotographic properties. These not only relieve the residual stress in the charge transport layer.

The layer may simultaneously serve to improve the charge injection property from the conductive support or serve as a protective layer against electrical breakdown of the photosensitive layer, or these layers may be provided separately.

Each of the above layers is roll coating, air knife coating, gravure coating, day lag coating,
A sheet or drum-shaped photoreceptor can be formed by known coating means such as spray coating.

〔Example〕

EXAMPLES Below, Examples will be described to explain the present invention in more detail, but the present invention is not limited to these Examples.

Example 1 A solution of polycargonate (25 parts by weight of polycarbonate, 75 parts by weight of Diokipun Futarienko Moment 0D) was coated onto a slide glass using a wire parser so that the film thickness after drying was 251Rn.

After drying, cut out a sample measuring 20m x 60m.
A sample for a tensile test was prepared.

Since the sample cannot be directly placed in the tensile tester, the above sample was fixed to a member attached to the check of the tensile tester with Sekisui San 575 double-sided tape and pulled at room temperature at a speed of 10 tm/ml n. A tensile test was conducted. Shimadzu Auto Durham DO is used as the tensile test machine.
A model 8-2000 was used.

In this manner, a polymer coating was obtained in which the ratio of elongation at break to yield elongation was 1.39 as determined by a tensile tester. Next, an electrophotographic photoreceptor consisting of a charge transport layer using this solvent was fabricated, and a study was conducted on the occurrence of rubber vent cracks.

The electrophotographic photoreceptor shown in FIG. 1 contains 0.5 parts by weight of a charge generating substance which is a disazo pigment of the following structural formula (1), 1 part by weight of polyvinyl butyral, and 30 parts by weight of inpropyl alcohol on an aluminum cylinder. The mixture was dispersed for 4 hours using a sieve mill disperser. This dispersion was applied by dip coating and dried to form a charge generation layer. The film thickness was 0.3 mm. In FIG. 1, 1 is an aluminum cylinder, 2 is a charge generation layer, and a 3Fi charge transport layer.

Next, 1 part by weight of a charge transport material which is a hydrazone compound of the following structural formula (2), 1 part by weight of polycarbonate resin, and 6 parts by weight of dioxane were mixed and dissolved by stirring with a stirrer. This liquid was dip coated onto the charge generation layer and dried to form a charge transport layer. The film thickness was 25 μm.

A cloth soaked with plasticizer-containing oil was attached to the surface of the photoreceptor obtained in this way, and after being left overnight at room temperature, an image was produced using Canon's LBP-8X, and the photosensitive layer showed solvent cracks. When it was confirmed whether or not cracks were occurring, no cracks due to solvent cracks were observed, and a good image was obtained.

Example 2 When the charge transport material described in Example 1 was changed to one of the formula (3) below, a photoreceptor drum was produced in the same manner, and evaluated in the same manner, no solvent cracks were observed and good results were obtained. Image obtained.

Example 3 A sample was prepared in the same manner as in Example 1 by changing the charge transport layer coating solvent from dioxane to dichloromethane, and the ratio of elongation at break to yield elongation was 1.2. A jj' IJ mom membrane was obtained. This was used as a photoreceptor drum in the same manner as in Example 1, and solvent cracks were evaluated, and no solvent cracks were found to occur.

Example 4 A photoreceptor drum was produced in the same manner as in Example 3 using the charge transport material described in Example 2, and evaluated for solvent cracks. No solvent cracks were found to occur at all.

Example 5 The charge transport layer coating solvent described in Example 1 was changed from dioxane to 0-dichlorobenzene (dipole moment) of 2.27
D) 45 parts by weight and dichloromethane (dipole moment)
A photoreceptor drum was prepared in the same manner as in Example 1 using a mixture of 55 parts by weight of 1.14D) and evaluated for solvent cracks, and the ratio of elongation at break to yield elongation was 1.1.
5, and no solvent cracks occurred.

Comparative Example 1 A polymer film was prepared in the same manner as in Example 1 using 100 parts by weight of O-dichlorobenzene as the charge transport layer coating solvent described in Example 1, and a tensile test was performed, and no yield point was observed. . Further, when the photoreceptor drum was evaluated for solvent cracks under these conditions as in Example 1, a crack image that was clearly determined to be a crack was obtained after one night of adhesion.

Example 6 Polyamide resin (Toshi CM-80) on aluminum cylinder
00) A solution of 9 parts by weight and 1 part by weight of methano-A was dip coated to form an intermediate layer having a film thickness of 2 copper after drying, and then the charge generation layer and charge transport described in Comparative Example IK were applied. The layers were sequentially formed to produce an electrophotographic photoreceptor shown in FIG. When this was evaluated for solvent cracks in the same manner as in Example 1, no solvent cracks were found to occur. Second
In the figure, 1 to 3 are the same as in FIG. 1, and 4 is an intermediate layer.

Example 7 As the intermediate layer described in Example 6, a solution of 9 parts by weight of styrene-butadiene rubber (Asahi Kasei Tuffrene A) and 1 part by weight of toluene was dip-coated, and the intermediate layer had a film thickness of one layer after drying. A photosensitive drum was prepared in the same manner as in Example 6, and evaluated in the same manner as in Example 6. No solvent cracks were found to occur at all.

Example 8 As shown in FIG. 3, the charge transport layer described in Example 1 was applied by spray coating on the charge transport layer described in Comparative Example 1 to form a surface layer with a thickness of 5 μm, and the third The electrophotographic photoreceptor shown in the figure was prepared. Thereafter, solvent cracks were evaluated in the same manner as in Example 1, and no solvent cracks were found to occur. In Figure 3, 1~
3 is the same as in FIG. 1, and 5 is a surface layer.

〔Effect of the invention〕

As explained above, the binder resin used for the charge transport layer and/or the surface layer has a ratio of elongation at break to yield elongation at room temperature of greater than 1 and less than or equal to 10. The occurrence of solvent cracks can be suppressed by using a remer and by selecting a solvent with a dipole moment of 1.7D or less as the solvent for the binder resin. Solvent cracks can also be suppressed by forming a photosensitive layer by providing an intermediate layer on a conductive support.

Therefore, when installed in a copier, printer, etc.
Prints with good image quality can be obtained.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are schematic cross-sectional views of the electrophotographic photoreceptor of the present invention, respectively, and FIG.
The figure shows one with an intermediate layer, and FIG. 3 shows one with a surface layer. ...Aluminum cylinder...Charge generating layer, 3...Charge transport layer, 4...Intermediate layer,...Surface layer.

Claims (1)

[Scope of Claims] 1. In an electrophotographic photoreceptor having a photosensitive layer containing an organic photoconductor on a conductive support, the layer containing a charge transport substance and/or the binder resin of the surface layer is 1. An electrophotographic photoreceptor characterized in that the ratio of elongation at break to yield elongation at room temperature when formed is in a range of greater than 1 and less than or equal to 10. 2. The electrophotographic photoreceptor according to claim 1, wherein the coating solvent for the binder resin is one type of solvent or a mixed solvent of two or more types, and has a dipole moment of 1.7D or less. 3. Between the conductive support and the charge transport layer, a thickness of 0.2
2. The electrophotographic photoreceptor according to claim 1, further comprising an intermediate layer having a thickness of 5 .mu.m. 4. The electrophotographic photoreceptor according to claim 3, wherein the intermediate layer is a film obtained by curing a composition containing a polyamide resin or a thermosetting resin. 5. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the charge transport layer contains a polycarbonate resin.