JPH04355764A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain superior photosensitivity, electric charging characteristics, and stable residual potential characteristics by reducing the halogen content in a photosensitive layer to a specified value or less. CONSTITUTION:The electrophotographic sensitive body is provided with a conductive substrate and the photosensitive layer formed thereon, and the photosensitive layer contains halogen in an amount of <=5wt.%, preferably, <=1wt.%, especially, <=0.1wt.%, and the conductive substrate to be used may be made of whatever material so long as it is conventionally used, for example, metallic material like brass, aluminum, and gold, metals coated with thin plastic film on the surfaces, metal-coated paper and such a plastic sheet, glass coated with aluminum iodide, and the like.

Description

[Detailed description of the invention]

0001

[Purpose of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor that can be effectively used in the Carlson method, and more particularly to an electrophotographic photoreceptor having excellent photosensitivity, charging characteristics, and stable residual potential characteristics.

0003

2. Description of the Related Art The photoconductive process of electrophotographic photoreceptors consists of a photocharge generation process and a charge transport process. As electrophotographic photoreceptors, there are known those in which these processes are carried out using one substance, and those of so-called functionally separated type in which these processes are carried out using separate substances.

Of these two types of photoreceptors, the functionally separated type photoreceptor has a wider selection range of materials used for the photoreceptor, has excellent electrophotographic properties such as sensitivity and acceptance potential, and is easy to manufacture. It has the advantage of being able to produce films with excellent physical properties.

Examples of this type of functionally separated photoreceptor include one in which amorphous selenium is used for the charge generation layer (CGL) and polyvinylcarbazole is used for the charge transport layer (CTL);
One using methyl squarylic acid in the charge generation layer (CGL) and triarylpyrazoline in the charge transport layer (CTL) (JP-A-49-105536), Diane Blue in the charge generation layer (CGL), and oxadione in the charge generation layer (CGL). Using azole in the charge transport layer (CTL) (Japanese Patent Application Laid-Open No. 48-66444)
, a perylene pigment vapor-deposited film is used for the charge generation layer (CGL) and oxadiazole is used for the charge transport layer (CTL) (Japanese Patent Application Laid-Open No. 49-48334), a bisazo pigment is used for the charge generation layer (CTL)
CGL), styryl anthracene is added to the charge transport layer (CT
L) (Japanese Unexamined Patent Publication No. 54-109438), and one using a perylene pigment vapor-deposited film for the charge generation layer (CGL) and a triarylpyrazoline derivative for the charge transport layer (CTL) (Japanese Unexamined Patent Publication No. 55-1989). 36849) etc. are known.

However, these photoreceptors have several problems. For example, in a photoreceptor that uses amorphous selenium in the charge generation layer, the polyvinyl carbazole used in the charge transport layer lacks flexibility, so the formed film is hard and brittle, and can cause phenomena such as cracking and film peeling. It has the disadvantage that it is easy to use, and its durability as a photoreceptor is poor. Therefore, in order to increase the flexibility of polyvinylcarbazole, a method using a plasticizer has been proposed. However, with this method,
Residual charges in the charge transport layer increase, resulting in poor electrophotographic properties such as fogging of images.

[0007] In addition, all of the conventionally known photoreceptors described above do not have sufficient sensitivity, and furthermore, when repeatedly exposed and charged, they cause fluctuations in surface potential, particularly a decrease in charge retention ability. There are many things. In addition, changes in the environment,
In particular, it has the disadvantage that sensitivity and image contrast change with changes in humidity.

[0008]

As described above, conventional electrophotographic photoreceptors have problems in terms of photosensitivity, deterioration of characteristics due to repeated use, and deterioration of characteristics due to environment.

An object of the present invention is to eliminate the drawbacks of conventional electrophotographic photoreceptors and to provide an electrophotographic photoreceptor having excellent photosensitivity, charging characteristics, and stable residual potential characteristics. .

0010

[Structure of the invention]

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present inventors conducted studies on various components mixed or contained in an electrophotographic photoreceptor, and as a result, they arrived at the present invention. .

That is, the present invention comprises a conductive support and a photosensitive layer formed on the conductive support, and the content of halogen atoms in the photosensitive layer is 5% by weight or less. An electrophotographic photoreceptor is provided. Preferably, the content of halogen atoms in the photosensitive layer is 1% by weight or less,
More preferably, it is 0.1% by weight or less. The present invention will be further explained below by taking as an example a functionally separated laminated photoreceptor in which the photosensitive layer includes a charge generation layer and a charge transport layer.

[0013] The conductive support used in the present invention is not particularly limited and may be any support that is normally used as a conductive support for electrophotographic photoreceptors. Examples of such supports include metal materials such as brass, aluminum, gold, and silver; metal surfaces coated with a thin film of plastic; metal-coated paper;
metal coated plastic sheet or aluminum iodide,
Glass coated with a conductive layer such as copper iodide, chromium oxide or tin oxide; coated with conductive polymers such as polyacetylene, polyphenylene, polyparaphenylene vinylene, doped conductive polymers, conductive polymers Examples include metal, plastic, glass, etc.

[0014] These are used in the form of a cylinder or a sheet with appropriate thickness, hardness, and flexibility, and the support itself is electrically conductive or its surface is electrically conductive, making it easy to handle. It is preferable that the material has high strength. A charge generation layer and a charge transport layer, which will be described later, are formed on such a conductive support.

The charge generation layer may be made of any material as long as it absorbs light and generates charges (carriers) with high efficiency. Examples of such substances include selenium, selenium alloys, CdS, CdSe, and Cd
Inorganic photoconductors such as SSe, ZnO and ZnS; various crystalline metal phthalocyanine pigments such as titanyl phthalocyanine and vanadyl phthalocyanine, and various crystalline metal-free phthalocyanine pigments; monoazo dyes, bisazo dyes,
Azo dyes such as trisazo dyes and tetrakisazo dyes;
Perylene pigments such as perylene anhydride and perylene imide; perylene pigments; indigo dyes; quinacridone pigments;
Polycyclic quinone pigments such as anthraquinone and dibromoanthanthrone; cyanine dyes;
Examples include charge transfer complexes consisting of an electron-donating substance such as poly-N-vinylcarbazole and an electron-accepting substance such as trinitrofluorenone.

[0016] The charge generation layer may be formed only from a charge generation substance, or may be formed from polyvinyl butyral resin,
It may be formed together with a binder such as phenoxy resin. The method for forming the charge generation layer varies depending on the type of charge generation substance used, but examples include various coating methods such as spin coating, dipping and pulling up, roller coating, doctor blade coating, spray coating, and vacuum evaporation. For example, a plasma CVD method using glow discharge, a sputtering method, a plasma CVD method, etc. can be appropriately selected and employed. The thickness of the charge generation layer is appropriately determined depending on the charging characteristics required for the electrophotographic photoreceptor, but is usually 0.2 to 20μ.
m is desirable.

[0017] When forming the charge generation layer on the conductive support, an adhesive layer may be formed between the conductive support and the charge generation layer if necessary. As the adhesive layer, materials commonly used in the past, such as casein, can be used. The thickness of the adhesive layer is preferably 0.1 to 10 μm
, more preferably 0.2 to 2 μm, most preferably 0.2 μm.
Approximately 5 to 2 μm is preferable.

As the charge transport material constituting the charge transport layer, a material that can maintain a desired charging potential when positively or negatively charged can be used. In a functionally separated photoreceptor in which a charge transport layer is provided on a charge generation layer,
The charge transport material must transmit enough light to generate charges in the charge generation layer when irradiated with light, but in a functionally separated photoreceptor in which the charge generation layer is provided on the charge transport layer,
No such optical transparency is required.

Examples of charge transport substances include hydrazone compounds, pyrazoline compounds, oxazole compounds, oxadiazole compounds, thiazole compounds, thiadiazole compounds, imino compounds, ketazine compounds, enamine compounds, amidine compounds, stilbene compounds, butadiene compounds, carbazole Examples include low-molecular compounds such as compounds, and high-molecular compounds introduced into the main chain or side chain of these polymers.

As a method for forming the charge transport layer, when the charge transport material does not have film-forming properties, the following polymeric compound is dissolved as a binder in a suitable solvent, and the above-mentioned charge transport layer is dissolved in a suitable solvent. A suitable method is to prepare a coating liquid by dissolving or dispersing the substance, apply this coating liquid by a conventional coating method, and then dry it. Note that if the charge transport material has film-forming properties, a binder is not necessarily required.

[0021] Examples of the polymer compound that can be used as a binder include polycarbonate, polyester, polyester carbonate, polyvinyl chloride, acrylic resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinyl acetal, phenol resin, styrene-acrylic resin. Examples of polymer compounds known as binders for electrophotographic photoreceptors include copolymers, polyarylates, alkyd resins, and phenoxy resins. In this case, it is preferable to mix 0.3 to 2 parts by weight of the polymer compound with respect to 1 part by weight of the charge transport material. Examples of the solvent include aliphatic chlorine-based, aromatic hydrocarbon-based, aromatic chlorine-based, ether-based, ester-based, and ketone-based organic solvents. As the coating method, for example, a spin coating method, a pulling method, a roller coating method, a doctor blade coating method, etc. can be used.

[0022] The thickness of the charge transport layer is usually 10 to 30 μm.
is preferred. Further, the total thickness of the charge generation layer and the charge transport layer is preferably determined to be 100 μm or less, more preferably 10 to 30 μm. . This is because if the total thickness of both exceeds 100 μm, the flexibility and photosensitivity of the formed photosensitive layer may decrease. On top of the photosensitive layer explained above, a 5 μm thick film made of urethane resin or acrylic copolymer is added.
It is also possible to provide a surface layer of about The following method can be used to reduce the content of halogen atoms in the photosensitive layer to 5% by weight or less.

1. A compound that does not contain halogen atoms is used as a solvent in a coating solution for forming a charge transport layer, a charge generation layer, etc. In this case, it is necessary to use a charge transporting substance, a charge generating substance, a binder for the charge generating layer, and a binder for the charge transporting layer, which are dissolved in the solvent and are made of a compound other than a compound containing a halogen atom.

Examples of solvents that do not contain halogen atoms include aromatic hydrocarbons such as toluene and xylene; esters such as methyl ethyl ketone, cyclohexanone, and isophorone; esters such as ethyl acetate and amyl acetate; cellosolves such as ethyl cellosolve and cello acetate; halogenated hydrocarbons such as trichloroethane, dichloroethane, and chlorobenzene; alcohols such as butanol and amyl alcohol; and ethers such as THF and dioxane. Moreover, several kinds of these can also be mixed and used. Examples include mixtures of toluene and isophorone. In the case of a mixture of toluene and isophorone, the mixing ratio (weight ratio) is preferably 1:5 to 5:1. 2.
Do not use compounds containing halogen atoms as solvents for synthesis and purification of charge transport substances and charge generation substances. 3. A charge transport material, a charge generation material, a charge generation layer binder, and a charge transport layer binder having a halogen atom content of 5% by weight or less should be used.

4. After forming the photosensitive layer, the photosensitive layer is dried under heat to increase the volatilization of the solvent, etc. Note that the heating conditions in this case vary depending on the type of charge transport material, charge generation material, binder, solvent, etc. used.

5. After forming the photosensitive layer, the photosensitive layer is dried while blowing air to increase the volatilization of the solvent. In addition, in an electrophotographic photoreceptor, since the halogen element contained in the photosensitive layer is usually caused by a solvent remaining in the photosensitive layer, method 1 above is particularly preferable in the present invention.

Although the functionally separated laminated photoreceptor has been described above as an example, the present invention may be of either positive charging or negative charging. Furthermore, it may be a single-layer type photoreceptor in which a charge generating substance and a charge transporting substance are mixed and dispersed in a photosensitive layer.

[0028]

[Function] In the electrophotographic photoreceptor as described above, the electrophotographic properties can be improved by using a photosensitive layer containing 5% by weight or less of halogen atoms. Significant improvements in properties can be realized in the electrophotographic photoreceptor used in the photosensitive layer.

[0029]

EXAMPLES The present invention will be explained in more detail below by showing various examples and comparative examples of the present invention. Note that the present invention is not limited to these Examples. Example 1

Using a polyethylene terephthalate film on which an aluminum film is vapor-deposited as a conductive support, τ-type metal-free phthalocyanine (1 part by weight) and butyral resin (1 part by weight) are added to the surface on which the aluminum film is vapor-deposited. ) dispersed in cyclohexanone was applied by a coating method to form a charge generation layer with a thickness of 0.2 μm.

On this charge generation layer, 10 parts by weight of a charge transport material having the structural formula shown below [Chemical formula 1] and 10 parts by weight of polycarbonate Z (manufactured by Teijin Chemicals) were added to 44 parts by weight of toluene.
A solution prepared by dissolving 22 parts by weight of isophorone in a solvent was applied by dip coating and dried by heating to form a charge transport layer with a thickness of 20 μm.

Chargeability (initial value of photoreceptor surface potential when charged) and photosensitivity (exposure amount required for the initial value of surface potential to attenuate to 1/2) of the photoreceptor thus obtained and residual potential (dark decay rate) were measured. The results are shown in Table 1. The halogen content of this photoreceptor was found to be 0% by weight as determined by elemental analysis. Example 2

Example 1 except that 1,2-dichloroethane was used instead of the solvent consisting of toluene and isophorone and the charge transport layer was formed by drying at 60° C. for 12 hours.
An electrophotographic photoreceptor was prepared in the same manner as described above. The charging ability, photosensitivity, and residual potential of the photoreceptor thus obtained were measured. The results are shown in Table 1. The chlorine content of this photoreceptor was found to be 5.0% by weight as determined by elemental analysis. Example 3

[
Example 1 was carried out in the same manner as in Example 1, except that 1,2-trichloroethane was used instead of the solvent consisting of toluene and isophorone, and a charge transport layer was formed by drying at 90° C. for 10 hours in a hot air circulation dryer. An electrophotographic photoreceptor was prepared. The charging ability, photosensitivity, and residual potential of the photoreceptor thus obtained were measured. The results are shown in Table 1. The chlorine content of this photoreceptor was determined by elemental analysis to be 2.3% by weight. Comparative example 1

An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 1.5 parts by weight of 1,2,4,5-tetrachlorobenzene was added to the solution for forming the charge transport layer. The charging ability, photosensitivity, and residual potential of the photoreceptor thus obtained were measured. The results are shown in Table 1. The chlorine content of this photoreceptor was found to be 7.5% by weight as determined by elemental analysis. Comparative example 2

An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 1,2-dichloroethane was used instead of the solvent consisting of toluene and isophorone, and a charge transport layer was formed by drying at 40° C. for 9 hours. It was created. The charging ability, photosensitivity, and residual potential of the photoreceptor thus obtained were measured. The results are shown in Table 1. The chlorine content of this photoreceptor was found to be 5.8% by weight as determined by elemental analysis. Comparative example 3

An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that methylene chloride was used instead of the solvent consisting of toluene and isophorone, and a charge transport layer was formed by drying at room temperature for 12 hours. The charging ability, photosensitivity, and residual potential of the photoreceptor thus obtained were measured. The results are shown in Table 1. The chlorine content of this photoreceptor was found to be 8.7% by weight as determined by elemental analysis.

As shown in [Table 1], an electrophotographic photoreceptor with a chlorine content of 5% by weight or less has a chlorine content of 5% by weight or less.
Excellent charging ability, photosensitivity,
Residual potential is obtained.

Furthermore, the photoreceptors obtained in Examples 1, 2, and 3 were
Charging and exposure in environments where heat, ozone, etc. are generated
When the test was repeated ,000 times, almost no abnormality was observed, and fluctuations in charging ability, photosensitivity, residual potential, etc. were small, and fatigue resistance was found to be excellent. On the other hand, the photoreceptors obtained in Comparative Examples 1 to 3 were charged and charged in an environment where heat, ozone, etc. are generated.
When the exposure was repeated 10,000 times, abnormalities were observed, and it was found that the fatigue resistance was inferior to that of the photoreceptor obtained in Example 1.

[0040]

[Chemical formula 1]

[0041]

[Table 1]

[0042]

[Effects of the Invention] As explained above, according to the present invention,
Since a photosensitive layer containing 5% or less of halogen atoms is used, an electrophotographic photoreceptor having excellent photosensitivity, charging characteristics, and stable residual potential characteristics can be obtained.

Claims (1)

[Claims] 1. A method comprising a conductive support and a photosensitive layer formed on the conductive support, wherein the content of halogen atoms in the photosensitive layer is 5% or less by weight. Electrophotographic photoreceptor.