JPH02156251A - Electrophotograhic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and potential stability at the time of repeated uses by incorporating a specified 1,8-naphthalocyanine derivatige in a photosensitive layer. CONSTITUTION:The photosensitive layer formed on a conductive substrate contains one of the 1,8-naphthalocyanine derivatives represented by formula I in which R is H, nitro, alkyl, such as methyl or ethyl, aralkyl, such as benzyl, halogen, such as F, Cl, or Br, and n is an integer of 1-6, thus permitting potential stability at the time of repeated uses and sensitivity to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a 1,8-naphthalocyanine derivative having a specific structure.

[Conventional technology]

Inorganic photoconductors such as selenium, cadmium sulfide, and lead oxide are known as photoconductors used in electrophotographic processes. However, compared to these inorganic photoconductors, electrophotographic photoreceptors using organic photoconductors have better film forming properties. It has the advantage of being able to be produced by I-processing, extremely high productivity, and being able to provide an inexpensive electrophotographic photoreceptor.

In addition, depending on the selection of sensitizers such as dyes and pigments used,
It has the advantage of being able to freely control color sensitivity, and has been extensively tested.

Phthalocyanine pigments are known to be stable against heat and light and exhibit a deep blue color, and have recently attracted attention as organic materials that can be put to practical use not only as pigments but also as electronic materials and catalysts.

In the field of electrophotographic photoreceptors, numerous studies have been conducted, including US Pat. No. 3,816,418, which proposed the use of phthalocyanine pigments.

Documents related to high-sensitivity phthalocyanine for electrophotographic photoreceptors include Japanese Patent Application Laid-Open No. 1983-1987, which uses vanadium phthalocyanine.
JP-A-146255, JP-A-62-119547 using dihalogenotin phthalocyanine, JP-A-59-49544 using titanyloxyphthalocyanine, and JP-A-63 using chloroindium chlorophthalocyanine as a phthalocyanine derivative. -5
Publication No. 6564 and JP-A-63 using naphthalocyanine
-55556, etc.

However, electrophotographic photoreceptors using conventional phthalocyanine pigments generally have a high residual potential.

These materials are not necessarily satisfactory in terms of potential stability and sensitivity during repeated use, and only a few materials have been put into practical use.

[Problems to be Solved by the Invention] An object of the present invention is to improve the above-mentioned conventional drawbacks of phthalocyanine-based materials and to provide an electrophotographic photoreceptor that can be put into practical use.

[Means for Solving the Problems 1 Effect] The present invention provides an electrophotographic photoreceptor having a photosensitive layer on a conductive support, in which the photosensitive layer has a 1.8-
An electrophotographic photoreceptor characterized by containing a naphthalocyanine derivative.

In the formula, R represents a hydrogen atom, a nitro group, an alkyl group, an aralkyl group, or a halogen group, and n represents an integer of 1 to 6.

Specifically, examples of the alkyl group include groups such as methyl and ethyl, examples of the aralkyl group include groups such as benzyl, and examples of the halogen group include groups such as fluorine atom, chlorine atom, and bromine atom.

The 1,8-naphthalocyanine derivative represented by the general formula used in the present invention is produced using the method described by Le, Kaplan et al. (Mo1.Cryst, Liq, Cry
st.

, 1984. Vol, 112. pp, 345-3, one representative example of the compound represented by the above general formula is listed below.

Note that isomers exist depending on the compound.

For example, in the general formula R knee CJ1. When n:1, a mixture of four isomers represented by the following structural formulas (1), (2), (3) and (4) is obtained.

Hereinafter, for such compounds, only the Hitotsubashi formula among isomers will be described.

Compound Example (1) Compound Example (2) Compound Example (3) Compound Example (4) Compound Example (5) Compound Example (6) The electrophotographic photoreceptor of the present invention has a compound represented by the general formula 1 on a conductive support. .8-A photosensitive layer containing a naphthalocyanine derivative. The form of the photosensitive layer may be any known form, but the photosensitive layer containing a 1,8-naphthalocyanine derivative represented by the general formula is used as a charge generation layer, and a charge transporting layer containing a charge transporting substance therein is used. A functionally separated photosensitive layer in which layers are laminated is particularly preferred.

The charge generation layer can be formed by coating a coating solution in which a 1,8-naphthalocyanine derivative represented by the general formula is dispersed together with a binder resin in an appropriate solvent on a conductive support by a known method. The film thickness is preferably 5 Bm or less, preferably 0.1 to Ig.m, and the binder resin used in this case is selected from a wide range of insulating resins or organic photoconductive polymers. However, polyvinyl butyral, polyvinyl benzal, polyarylate, polycarbonate polyester, phenoxy resin, cellulose resin, acrylic resin, polyurethane, etc. are preferable, and the content thereof in the charge generation layer is 80% by weight or less, preferably 40% by weight or less. weight%
It is as follows.

The solvent used is preferably selected from those that dissolve the resin described above but do not dissolve the charge transport layer or undercoat layer described later.

Specifically, ethers such as tetrahydrofuran and 1,4-diosane, ketones such as cyclohexanone and methyl ethyl ketone, amides such as N,N-dimethylformamide, esters such as methyl acetate and ethyl acetate, toluene, Examples include aromatics such as xylene and chlorobenzene, alcohols such as methanol, ethanol, and 2-propanol, and aliphatic halogenated hydrocarbons such as chloroform, methylene monide, dichloroethylene, carbon tetrachloride, and trichloroethylene. .

The charge transport layer is laminated above or below the charge generation layer, and has the function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them.

The charge transport layer is formed by dissolving a charge transport material in a solvent together with an appropriate binder resin as necessary and coating the layer, and the film thickness is generally 5 to 40 gm.
5 to 30 Bm is preferred.

Charge transporting substances include electron transporting substances and hole transporting substances. Examples of electron transporting substances include 2゜4,7-dolinitrofluorenone, 2,4,5゜7-titranitrofluorenone, chloranil, and tetranitrofluorenone. Examples include electron-withdrawing substances such as cyanoquinodimethane, and polymerization of these electron-withdrawing substances.

Hole-transporting substances include polycyclic aromatic compounds such as pyrene and anthracene, carbazole-based, indole-based, imidazole-based, oxazole-based, thiazole-based, oxadiazole-based, pyrazole-based pyrazoline-based, thiadiazole-based, triazole-based compounds, etc. heterocyclic compound, p-
Hydrazone-based compounds such as diethylaminobenzaldehyde-N,N-diphenylhydrazone, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, α-phenyl-4'-N,N-17phenylaminostilbene, 5 -[4-(p-tolylamine)benzylidene]-5H-dibenzo[a, d] A styryl compound such as cycloheptene, a benzidine compound, a triarylmethane compound, triphenylamine, or a group consisting of these compounds. Polymers in the main chain or side chains (e.g. poly-N-vinylcarbazole).

polyvinylanthracene, etc.).

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide can also be used.

Further, these charge transport materials can be used alone or in combination of two of them.

When the charge transport material does not have film-forming properties, a suitable binder can be used. Specifically, insulating resins such as acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, polyacrylamide, polyamide, and chlorinated rubber, or organic light materials such as poly-N-vinylcarhesol and polyvinylanthracene. Examples include conductive polymers.

Examples of the conductive support on which the photosensitive layer is formed include aluminum, aluminum alloy, copper, zinc stainless steel, vanadium, molybdenum, chromium titanium, nickel, indium, gold, and platinum. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, etc.) in which such metals or alloys are coated by vacuum deposition, or conductive particles (e.g., carbon black, silver particles, etc.) are coated with a suitable binder resin. In addition, a support coated on a plastic or metal substrate, or a support made of plastic or paper impregnated with conductive particles can be used.

A subbing layer having a healer function and an adhesive function can also be provided between the conductive support and the photosensitive layer.

The subbing layer can be formed of casein, polyvinyl alcohol, nitrocellulose, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, aluminum oxide, or the like.

The thickness of the undercoat layer is suitably 5 JLm or less, preferably 0.1 to 3 JLm.

As another specific example of the present invention, 1.8 represented by the above general formula
- An electrophotographic photoreceptor containing a naphthalocyanine derivative and a charge transport substance in the same layer can be mentioned.

At this time, a charge transfer complex consisting of poly-N-vinylcarbazole and trinitrofluorenone can also be used as the charge transport substance.

The electrophotographic photoreceptor of this example can be formed by coating and drying a solution in which the above-mentioned derivative and charge transfer complex are dispersed in a suitable resin solution.

The pigment used in any electrophotographic photoreceptor contains at least one type of pigment selected from 1,8-naphthalocyanine derivatives represented by the general formula, and its crystal form may be amorphous or crystalline. Furthermore, if necessary, it is also possible to use a combination of two or more types of 1,8-naphthalocyanine derivatives represented by the general formula or a combination with a known charge generating substance.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in a wide range of electrophotographic applications such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

[Example] Examples 1 to 8 0.0% on an aluminum plate. An undercoat layer made of lILm vinyl chloride-maleic anhydride-vinyl acetate copolymer was provided.

Next, add 5 g of exemplified pigment (1) to 95 ml of cyclohexanone.
A solution containing 2 g of butyral resin (degree of butyralization 63 mol %, number average molecular weight 20,000) was added to the solution and dispersed in a sand mill for 20 hours.

This dispersion was applied onto the previously formed subbing layer using a Mayer bar so that the film thickness after drying was 0.5 gm, and dried to form a charge generation layer.

5g of hydrazone compound and polymethyl methacrylate) (
Dissolve 5 g of a (average molecular weight 10,000) in 70 m of chlorobenzene and apply it on the charge generation layer so that the film thickness after drying is 20 p.
The electrophotographic photoreceptor of Example 1 was prepared by coating with a Mayer bar so as to have a thickness of m and drying to form a charge transport layer.

Examples 2 to 2 using other exemplary pigments in place of exemplary pigment (1)
An electrophotographic photoreceptor corresponding to No. 8 was prepared in exactly the same manner.

The prepared electrophotographic photoreceptor was statically charged with corona at -5°5 KV using an electrostatic copying paper tester Model 5P-428 manufactured by Kawaguchi Denki Co., Ltd., held in a dark place for 1 second, and then exposed to light at an illumination intensity of 10 lux. The charging characteristics were investigated.

The charging characteristics are the surface potential (VQ) and the exposure t (E
l/2) was measured. Also, the surface potential V after 30 seconds of exposure
R and M remained constant. Show the results.

l (1) 6'lO2 8 (8) 685 2.6 12 Example 9 Example face 4 (6) was dissolved in 80 g of 1 hydrochloric acid and 5
Then, it was dropped into 200 mu of pure water to regenerate the IEJ material. Il! The mixture was separated, washed with warm water, 50% aqueous sodium carbonate solution, and hot water in that order, and dried under reduced pressure to obtain a blue pigment with metallic luster.

A corresponding electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the obtained pigment was replaced with the pigment used in Example 1, and evaluated in the same manner as in Example 1.

Show the results.

V, Knee 690V El/2: 2.71uxIIsec V Good Knee 11V Examples 1O to 12 100mA of glass beads with a particle size of 0.3mm were placed in a 300m beaker, and 1 example pigment (2) and 150ml of α-chloronaphthalene were added. The mixture was heated and stirred at 150° C. for 2 hours.

After cooling to room temperature, the glass beads were separated, thoroughly washed with ethanol and hot water in that order, and dried.

Except that the obtained pigment was replaced with the pigment of Example 1.

An electrophotographic photoreceptor of Example 10 was prepared in exactly the same manner as in Example 1, and evaluated in the same manner as in Example 1.

Further, electrophotographic photoreceptors corresponding to Examples 11 and 12 were prepared by changing the pigment, the solvent used in the treatment, the treatment temperature, and the treatment time, and were evaluated in the same manner.

Show the results.

Processing requirements Naphthalene 11 (4) THF 150 51
2 (5) Cyclohex 100 2 San ■ 2 , 8 2 , 7 2.8 Example 13 Example pigment (7) was coated on an aluminum plate with a film thickness of 100 mg/m2.
A charge generation layer was formed by vacuum evaporation to form a charge generation layer.

A solution prepared by dissolving 5 g of benzylidene compound and 5 g of bisphenol Z type polycarbonate (viscosity average molecular weight 30,000) in 32.5 g of chlorobenzene was applied onto the charge generation layer so that the film thickness after drying was 20 JLm, and one load was transported. formed a layer.

The charging characteristics of the produced electrophotographic photoreceptor were measured in the same manner as in Example 1. Show the results.

vo Knee 705V El/2: 2.9Jlux・5ec Vq Knee 8V Examples 14 to 16 Using the electrophotographic photoreceptors prepared in Examples 1, 3 and 5, fluctuations in bright area potential and dark area potential during repeated use were investigated. It was measured.

As a method, the photoreceptor was attached to the cylinder of an electrophotographic copying machine equipped with a -5.6 KV corona charger exposure optical system, a developing device, a transfer charger, a static elimination exposure optical system, and a cleaner. This copying machine is configured to produce an image on transfer paper as the cylinder is driven.

Using this copying machine, the initial bright area potential (VL) and dark area potential (Vo) were measured at -100V and -600V.
Bright area potential after setting around v and using 5,000 times,
The dark potential was measured.

It turns out that it is good.

Comparative Examples 1 to 3 Electrophotographic photoreceptors were prepared in exactly the same manner as in Example 1, except that a phthalocyanine pigment represented by the following structural formula was used in place of the exemplified pigment (1) in Example 1, and the charging characteristics were similarly determined. evaluated.

Comparative Example 1 (corresponding to Example 1) Pigment structural formula % Formula % From the above results, the potential stability during long-term use is good.
Knee 680V El/2: lO, oiux*5ecV machine Knee 10
0V Comparative Example 2 (corresponding to Example 2) Pigment Structural Formula % Formula % Near Comparative Example 3 ('8 vs. Example 7) Pigment Structural Formula % Formula %: 35 From the above results, it can be seen that the electrophotographic photoreceptor of the present invention It can be seen that it has excellent characteristics such as high sensitivity and low residual potential.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention has extremely high sensitivity by containing a 1,8-naphthalocyanine derivative with a specific structure in the photosensitive layer, and also has improved potential stability during repeated use. It has a remarkable effect of being superior.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor having a photosensitive layer on a conductive support, characterized in that the photosensitive layer contains a 1,8-naphthalocyanine derivative represented by the following general formula: Photographic photoreceptor. General formula ▲ There are numerical formulas, chemical formulas, tables, etc. ▼ In the formula, R represents a hydrogen atom, a nitro group, an alkyl group, an aralkyl group, or a halogen group, and n represents an integer of 1 to 6.