JPH0785169B2 - Photoconductor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component.

2. Description of the Related Art Generally, in electrophotography, the surface of a photosensitive layer of a photoconductor is charged and exposed to form an electrostatic latent image, which is developed with a developer to be visualized. Direct method of fixing on top to obtain a copy image, or powder image transfer method of transferring a visible image on a photoreceptor onto a transfer paper such as paper and fixing the transferred image to obtain a copy image or on a photoreceptor Transfer the electrostatic latent image onto the transfer paper and develop the electrostatic latent image on the transfer paper.
A latent image transfer method for fixing is known.

Conventionally, it has been known to use an inorganic photoconductive material such as selenium, cadmium sulfide, or zinc oxide as a photoconductive material for forming a photosensitive layer of a photoconductor used in this type of electrophotography. . These photoconductive materials have many advantages, such as being able to be charged to an appropriate potential in the dark, having a small dissipation of electric charges in the dark, or being capable of rapidly dissipating electric charges by irradiation with light. On the other hand, it has the following various drawbacks. For example, with selenium-based photoreceptors,
The manufacturing cost is high, and it is vulnerable to heat and mechanical shocks, so it requires careful handling. In addition, with cadmium sulfide-based photoreceptors and zinc oxide photoreceptors, stable sensitivity cannot be obtained in humid environments, and the dye added as a sensitizer causes charge deterioration due to corona charging and photobleaching due to exposure. It has a drawback that stable characteristics cannot be provided over a long period of time.

On the other hand, various organic photoconductive polymers such as polyvinylcarbazole have been proposed, but these polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film-forming property and light weight. However, it is still inferior to inorganic photoconductive materials in terms of sufficient sensitivity, durability and stability due to environmental changes.

Problems to be Solved by the Invention On the other hand, low molecular weight organic photoconductive compounds can control the physical properties of the coating film or the electrophotographic characteristics by selecting the type of binder to be used, the composition ratio and the like. It is preferable in that it can be done.

For example, U.S. Pat. No. 3,189,447 discloses 2,5-bis (P
-Diethylaminophenyl) -1,3,4-oxadiazole, U.S. Pat. No. 3,820,989 describes diarylalkane derivatives, and JP-A-54-59143 describes hydrazone compounds.

An object of the present invention is to provide a photoconductor containing a novel organic photoconductive compound having excellent charge transporting ability. Another object of the present invention is to provide a photoreceptor having high sensitivity and low residual potential. It is still another object of the present invention to provide a photoconductor which has less fatigue deterioration due to repeated use, has good stability to light and has excellent durability.

Means for Solving the Problems The present invention achieves the above object by using a specific styryl compound as a charge transport material of a photoreceptor.

The present invention relates to a photoreceptor containing at least one styryl compound represented by the following general formulas [I], [II] and [III] as a charge transport material: [Wherein R ₁ represents an alkyl group or an aralkyl group; R ₂
Represents an alkyl group, an aralkyl group or an aryl group,
Each group may have a substituent; R ₃ is hydrogen,
Represents an alkyl group, an alkoxy group, an aralkyl group or an aralkyloxy group; R ₄ represents hydrogen, an alkyl group, an alkoxy group or an aralkyl group; R ₅ represents a condensed polycyclic group or a heterocyclic group, and each group represents R ₆ may have a substituent; R ₆ represents an aryl group, a condensed polycyclic group or a heterocyclic group, and each group may have a substituent; R ₇
Represents hydrogen or an alkyl group; m represents a number of 1 or 2. ].

Preferred specific examples of the styryl compounds represented by the general formulas [I] to [III] according to the present invention include, but are not limited to, those having the following structural formulas.

The styryl compounds represented by the general formulas [I] to [III] according to the present invention can be easily produced by known methods. For example, the following general formula [IV]: [Wherein R ₄ and m have the same meanings as [I] to [III], n represents a number of 0 or 1, and X represents triphenyl or trialkyl represented by —P ⁺ (R ₇ ) ₃ Y ^—. A phosphonium group or a dialkylphosphorous acid group represented by —PO (OR ₈ ) ₂ is shown. R ₇ represents an alkyl group, an aryl group, R ₈ represents an alkyl group, and Y represents a halogen ion. ] It can obtain by making the phosphorus compound represented by these and the carbonyl compound represented by following General formula [V]-[VII] react.

R ₅ -CH = O [VI] R ₄ -CH = O [VII] [wherein R ₁ , R ₂ , R ₃ , R ₅ , R ₆ and R ₇ have the same meanings as [I] to [III]] The phosphorus compound represented by the general formula [IV] can be obtained by heating the corresponding halomethyl compound and triarylphosphine or trialkylphosphine, or trialkylphosphite directly or in a solvent such as toluene or xylene.

As the reaction solvent in the above method, for example, hydrocarbons, alcohols and ethers are preferable, and methanol, ethanol, isopropanol, butanol, 2-methoxyethanol, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, dioxane are used. , Tetrahydrofuran, toluene, xylene, dimethyl sulfoxide, N, N
-Dimethylformamide, N-methylpyrrolidone, 1,3
-Dimethyl-2-imidazolidinone and the like. Among these solvents, polar solvents such as N, N-dimethylformamide and dimethylsulfoxide are preferable.

As the condensing agent, an alcoholate such as caustic soda, caustic potash, sodium sodium hydrogen amide and sodium methylate, and potassium t-butoxide is used.

The reaction temperature can be selected in a wide range from about 0 ° C to 100 ° C, but is preferably 10 ° C to 80 ° C.

First Construction Example of Photoreceptor Using Styryl Compound of the Present Invention
It is schematically shown in FIGS.

FIG. 1 shows a photoreceptor in which a photoconductive layer (4) in which a photoconductive material (3) and a charge transport material (2) are mixed with a binder is formed on a substrate (1). The styryl compound of the present invention is used.

FIG. 2 shows a function-separated type photoreceptor having a charge generation layer (6) and a charge transport layer (5) as a photosensitive layer. The charge transport layer (5) is formed on the surface of the charge generation layer (6). There is. The styryl compound of the present invention is incorporated in the charge transport layer (5).

Similar to FIG. 2, FIG. 3 shows a function-separated type photoreceptor having a charge generation layer (6) and a charge transport layer (5). On the contrary to FIG. A charge generation layer (6) is formed.

FIG. 4 shows the surface of the photoreceptor of FIG. 2 further provided with a surface protective layer (6). The photosensitive layer (4) is divided into a charge generation layer (6) and a charge transport layer (5). It may be a function separation type.

FIG. 5 shows an intermediate layer (8) provided between the substrate (1) and the photosensitive layer (4). The intermediate layer (8) has improved adhesion, improved coatability, and substrate protection. , Can be provided to improve the charge injection property from the substrate to the photoconductive layer. As the intermediate layer, polyimide resin, polyester resin, polyvinyl butyral resin, casein or the like may be used. In the photoreceptor of this aspect, the photosensitive layer may have a function-separated type.

The photoreceptor of the present invention is prepared by dissolving or dispersing the styryl compound represented by any of the general formulas [I] to [III] in a suitable solvent together with a binder, and if necessary, a photoconductive material and an electron withdrawing compound, or A coating solution obtained by adding an infectious agent and other pigments is coated on a conductive substrate and dried, and usually 5
It can be produced by forming a photosensitive layer having a film thickness of 30 μm, preferably 6 to 20 μm.

Specifically, a function-separated type photoreceptor having the same structure as that shown in FIG. 2 which is obtained by stacking a charge generation layer and a charge transport layer on a conductive support has a photoconductive material on the conductive support. Vacuum evaporation, or a suitable solvent or, if necessary, dispersed in a solution in which a binder resin is dissolved, is applied and dried to form a charge generation layer, on which a styryl compound and a binder are formed. It is obtained by applying a solution in which is dissolved in a suitable solvent and drying it to form a charge transport layer. At this time, the thickness of the charge generation layer is 4 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer is 3 to 30 μm, preferably 5 to 20 μm. The proportion of the styryl compound in the charge transport layer is preferably 0.02 to 2 parts by weight, preferably 0.03 to 1.3 parts by weight, based on 1 part by weight of the binder. Also,
Other charge transport materials may be combined. In the case of a polymeric charge transport material that can itself be used as a binder,
It is not necessary to use another binder. The photosensitive member may have a structure in which a charge transport layer is formed on a conductive support and a charge generating layer is laminated on the charge transport layer, similarly to the photosensitive member shown in FIG.

A dispersion type photoconductor having a photosensitive layer laminated on a conductive support and having the same structure as the photoconductor of FIG. It is obtained by dispersing, coating this on a conductive support, and drying to form a photosensitive layer. The thickness of the photosensitive layer at this time is
The thickness is 3 to 30 μm, preferably 5 to 20 μm. If the amount of the photoconductive material used is too small, the sensitivity is poor, and if it is too large, the charging property is deteriorated or the strength of the photosensitive layer is weakened. 0.01 to 2 parts by weight, preferably 0.05 to 1 part by weight, is preferable, and the ratio of the styryl compound is 0.01 to 1 part by weight of the resin.
˜2 parts by weight, preferably 0.02 to 1.2 parts by weight. It may also be used in combination with a polymer photoconductor such as polyvinyl carbazole which itself can be used as a binder. It may also be combined with other charge transport materials such as hydrazone compounds.

Examples of materials used for the photoconductive material of the photoreceptor of the present invention include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, cyanine dyes, styryl dyes, pyrylium dyes. , Azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathlon pigments, squarylium pigments, phthalocyanine pigments, and other organic substances, selenium, selenium, Inorganic substances such as tellurium, selenium / arsenic, cadmium sulfide, and amorphous silicon can be given. Other than this,
Any material can be used as long as it absorbs light and generates charge carriers with extremely high efficiency.

As the binder in the present invention, all known electrically insulating thermoplastic resins, thermosetting resins and photocurable resins, and also photoconductive resins can be used.

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate copolymers, ionically cross-linked olefin copolymers (ionomers), styrene-butadiene blocks. Thermoplastic binders such as copolymers, polyacrylates, polycarbonates, vinyl chloride-vinyl acetate copolymers, cellulose esters, polyimides, styrene resins; epoxy resins, urethane resins, silicone resins, phenol resins, melamine resins, xylene resins. , Thermosetting binders such as alkyd resins and thermosetting acrylic resins; photocurable resins; photoconductive resins such as poly-N-vinylcarbazole, polyvinylpyrene and polyvinylanthracene. These can be used alone or in combination.

These electrically insulating resins are individually measured 1 × 10 ¹² Ω · cm
It is desirable to have the above volume resistance. More preferred are polyester resin, polycarbonate resin, and acrylic resin.

The photoreceptor of the present invention, together with a binder, a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate and o-ta-phenyl,
Chloranil, tetracyanoethylene, 2,4,7-trinitro-9-fluorenone, 5,6-dicyanobenzoquinone,
Using electron-withdrawing sensitizers such as tetracyanoquinodimethane, tetrachlorophthalic anhydride and 3,5-dinitrobenzoic acid, sensitizers such as methyl violet, rhodamine B, cyanine dyes, pyrylium salts and thiapyrylium salts Good.

The photoreceptor thus formed may optionally have an adhesive layer / intermediate layer (8) and a surface protective layer (9) as shown in FIGS. 4 and 5 described above.

EFFECTS OF THE INVENTION The present invention provides a novel photoreceptor using the styryl compound represented by any of the general formulas [I] to [III] as an organic photoconductive compound having an excellent charge transporting ability. The photoconductor of the present invention has high sensitivity and a small residual potential, and even when repeatedly used, an excellent image can be obtained as in the initial stage.

Example 1 2 parts by weight of a bisazo pigment represented by the following formula, 1 part by weight of a polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.), and 100 parts by weight of methyl ethyl ketone were put in a ball mill pot and 2
Dispersed for 4 hours to obtain a photosensitive coating solution. This was applied onto an aluminum substrate and dried to form a charge generation layer having a thickness of 1 μm.

The styryl compound (5) described above is formed on the charge generation layer.
A coating solution prepared by dissolving 10 parts by weight and 10 parts by weight of polyarylate resin (U-100, manufactured by Unitika Ltd.) in 100 parts by weight of chlorobenzene is applied and dried to form a charge transporting layer having a thickness of 20 μm, and a photoconductor is formed. A was produced.

The photoconductor A thus obtained was subjected to corona charging at −6.0 KV using a commercially available electrophotographic copying machine (EP450Z manufactured by Minolta Camera Co., Ltd.) to obtain an initial surface potential V _O (V) and an initial surface potential. Exposure required to reduce to _1/2 E _1/2 (luxse
c) Decay rate D of initial surface potential when left in the dark for 5 seconds
DR ₅ (%) and residual potential V _R (V) were measured.

Example 2 Photoreceptors B and C having the same constitution as in Example 1 but using the styryl compounds (6) and (10) in place of the styryl compound (5) used in Example 1 were prepared. did.

With respect to the photoconductors B and C thus obtained, V _O , E _1/2 , DDR ₅ and V _R were measured in the same manner as in Example 1.

Example 3 50 parts by weight of copper phthalocyanine and 0.2 parts by weight of tetranitrocopper phthalocyanine were dissolved in 500 parts by weight of 98% concentrated sulfuric acid with sufficient stirring, and this was poured into 5,000 parts by weight of water, and photoconductivity of copper phthalocyanine and tetrinitrocopper phthalocyanine. After depositing the material composition, it was filtered, washed with water, and dried at 120 ° C. under reduced pressure.

10 parts by weight of the photoconductive composition thus obtained was used as a thermosetting acrylic resin (Acridic A405, Dainippon Ink and Chemicals, Inc.)
22.5 parts by weight, melamine resin (Super Beckamine J8)
20, 7.5 parts by weight of Dainippon Ink and Co., Ltd., and 10 parts by weight of the styryl compound (18) described above were placed in a ball mill pot together with 100 parts by weight of a mixed solvent prepared by mixing methyl ethyl ketone and xylene in the same amount, and dispersed for 48 hours. A photoconductive coating liquid was prepared, and the coating liquid was applied onto an aluminum substrate and dried to form a photosensitive layer having a thickness of about 15 μm, thereby preparing a photoconductor D.

With respect to the photoconductor D thus obtained, the same method as in Example 1 was used except that corona charging was performed at +6 KV to obtain V _O , E _1/2 and DD.
R ₅ and V _R were measured.

Example 4 A photoconductor E having the same structure as in Example 3 except that the styryl compound (23) was used in place of the styryl compound (18) used in Example 3 was prepared.

With respect to the photoconductor E thus obtained, V _O , E _1/2 , DDR ₅ and V _R were measured in the same manner as in Example 3.

Comparative Example 1 A photoconductor F was prepared in the same manner as in Example 3, except that the styryl compound (18) used in Example 3 was replaced by a styryl compound represented by the following formula.

With respect to the photoconductor F thus obtained, V _O , E _1/2 , DDR ₅ and V _R were measured in the same manner as in Example 3.

The measurement results of V _O , E _1/2 , DDR ₅ and V _R of the photoconductors A to E obtained in Examples 1 to 4 and the photoconductor F obtained in Comparative Example 1 are as shown in Table 1. is there.

As is clear from Table 1, the photoconductors A to E using the styryl compound of the present invention have a sufficient initial potential in the electrophotographic process, have excellent photosensitivity, have a low dark decay rate, and have good charging ability. In addition, the images 3 to 4 and the photoconductors D to E were repeatedly subjected to an actual copying test, and a clear image having excellent gradation was obtained after copying 10,000 sheets, and the photoconductor of the present invention has excellent repeatability. I understand. It can be seen that the photoconductor F of Comparative Example 1 has a poor photosensitivity and a large dark decay rate, and thus has a poor charging ability, and has a large residual potential, resulting in a decrease in sensitivity when repeatedly used.

[Brief description of drawings]

1 to 5 are schematic views of a photosensitive member according to the present invention, and FIGS. 1, 4, and 5 show a dispersion type photosensitive member obtained by laminating a photosensitive layer on a conductive support. The structure is shown in FIGS. 2 and 3 which shows the structure of a function-separated type photoreceptor in which a charge generation layer and a charge transport layer are laminated on a conductive support. DESCRIPTION OF SYMBOLS 1 ... Conductive support, 2 ... Charge transport material 3 ... Photoconductive material, 4 ... Photosensitive layer 5 ... Charge transport layer, 6 ... Photoconductive layer 7 ... Surface protective layer, 8 ... Middle class

Claims (1)

[Claims] 1. A conductive substrate having the following general formula [I]:
A photoreceptor having a photosensitive layer containing at least one styryl compound represented by [II] or [III] as a charge transport material: [Wherein R ₁ represents an alkyl group or an aralkyl group; R ₂
Represents an alkyl group, an aralkyl group or an aryl group,
Each group may have a substituent; R ₃ is hydrogen,
Represents an alkyl group, an alkoxy group, an aralkyl group or an aralkyloxy group; R ₄ represents hydrogen, an alkyl group, an alkoxy group or an aralkyl group; R ₅ represents a condensed polycyclic group or a heterocyclic group, and each group represents R ₆ may have a substituent; R ₆ represents an aryl group, a condensed polycyclic group or a heterocyclic group, and each group may have a substituent; R ₇
Represents hydrogen or an alkyl group; m represents a number of 1 or 2. ].