JPS61198163A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and to reduce residual potential after a durability test by incorporating a specified polycyclic quinone deriv. pigment in an electrostatic charge generating layer and a specified pyrazoline deriv. in a charge transfer layer. CONSTITUTION:The laminate type electrophotographic sensitive body is obtained by laminating on a conductive substrate the 2 layers of the charge generating layer composed essentially of a charge generating material of a polycyclic quinone deriv. represented by formula (1) and a charge transfer layer composed essentially of a charge transfer material of a pyrazoline deriv. represented by formula (2) in which R1, R2 are each alkyl, or an atomic group necessary for combining with each other and together with the adjacent N atom to form a ring, and each is optionally same or different, and X is a pyridyl or quinolyl group optionally substd. at least one alkyl or alkoxy. As the binder usable at the time of forming the charge generating layer by coating, it can be selected from the wide range of insulating resins, besides, from org. photoconductive polymers, such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene, preferably, insulating resins, such as polyvinylbutyral and polyarylate, and it is used in an amt. of <=80wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an organic photoconductor, and more particularly to an electrophotographic photoreceptor having a charge transport layer and a charge generation layer.

2. Description of the Related Art Electrophotographic photoreceptors using inorganic photoconductors such as selenium, cadmium sulfide, and zinc oxide as photosensitive components have been known.

On the other hand, since the discovery that certain organic compounds exhibit photoconductivity, many organic photoconductors have been developed.

For example, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, carbazole,
Low-molecular organic photoconductors such as anthracene, pyrazolines, oxadiazoles, hydrazones, polyaryl alkanes, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, indigo dyes,
Organic pigments and dyes such as thioindigo dyes and methine squaric acid dyes are known.

In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded, making it possible to use a large number of photoconductive materials. Conductive organic pigments and dyes have been proposed.

For example, US Patent No. 4123270, US Patent No. 424761
No. 4, No. 4251613, No. 4251614,
Same No. 4256821, Same No. 4260672, Same No. 4
No. 268596, No. 4278747, No. 4293
628, an electrophotographic photoreceptor using a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer is known.

Electrophotographic photoreceptors using such organic photoconductors can be produced by coating by appropriately selecting a binder, making it possible to provide photoreceptors with extremely high productivity and low cost.
Moreover, it has the advantage that the sensitive wavelength range can be freely controlled by the ',y1 folding of the organic pigment.

A multilayer photoreceptor obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material has higher sensitivity and higher residual potential after durability tests than other single layer photoreceptors. Although it is advantageous, it is still not at a sufficient level.

Problems to be Solved by the Invention An object of the present invention is to improve the above-mentioned drawbacks and provide a laminated electrophotographic photoreceptor with high sensitivity and extremely low residual potential even after a durability test.

Means for Solving Problems 1 Effect The above-mentioned object of the present invention is to form a two-layer structure on a conductive support, comprising a charge generation layer containing a charge generation material as a main component and a charge transport layer containing a charge transport material as a main component. In the multilayer electrophotographic photoreceptor having the above structure, this is achieved by using a polycyclic non-based pigment of structural formula (1) in the charge generation layer and a pyrazoline compound represented by general formula (2) in the charge transport layer. Ru.

Furthermore, a pyrazoline compound or the like used in the charge transport layer can be added to the charge generation layer, and the effect becomes more pronounced.

Further, the charge generation layer used in the invention may be used as a single layer, or a layer containing a mixture of a charge generation material and a charge transport material may be used as a single layer.

The present invention provides a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, in which the charge generation layer is composed of a layer containing a polycyclic non-based pigment represented by structural formula (1). ,
The charge transport layer is a pyrazoline compound represented by the general formula (2) (wherein R,,R are residues that form a ring together with an alkyl group or a nitrogen atom, and R and R are the same or different. X is an unsubstituted pyridyl group, quinolyl group, or a pyridyl group or quinolyl group substituted with at least one alkyl group or alkoxy group. It consists of a photographic photoreceptor.

Representative compounds of the pyrazoline compound represented by the general formula (2) used in the present invention are illustrated below.

In the rust layer type electrophotographic photoreceptor of the present invention, the charge generation layer contains as much of the L charge generation material as possible in order to obtain sufficient absorbance, and efficiently transfers the generated charge carriers to the charge transport layer. For implantation, a membrane layer, e.g. 10
1 with a film thickness of less than 0.0 g, preferably 0.01-1 g.
A layer of 11% is desirable.

This means that most of the incident light is collected by the charge generation layer and generates a large number of charge carriers, and that the generated charge carriers are not deactivated by recombination or trapping and are transferred to the charge transport layer. This is due to the need for injection.

The charge generation layer can be formed by coating the above-mentioned ring quinone pigment and, if necessary, a charge transporting material together with a suitable binder (or without a binder) on a substrate,
Alternatively, it can be obtained by forming a deposited film using a vacuum deposition apparatus.

When a charge transporting material is added to the charge generation layer, the amount of the pyrazoline compound is preferably 10 times or less (by weight), preferably 0.01 to 1 times (by weight) the charge generation material.

The binder that can be used in forming the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

Preferably polyvinyl butyral, polyarylate (
polycarbonate, polyester, phenoxy resin, polyvinyl acetate, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol,
Examples include insulating resins such as polyvinylpyrrolidone.

The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

Solvents that dissolve these resins vary depending on the type of resin, and are preferably selected from those that do not dissolve the underlying charge transport layer or subbing layer.

Specific organic solvents include methanol, ethanol,
Alcohols such as Impropatool, ketones such as acetone, methyl ethyl ketone, cyclohexanone, N, N
-dimethylformamide, N.

Amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate, ethyl acetate, chloroform, methylene chloride, dichloroethylene, Aliphatic halogenated hydrocarbons such as carbon chloride and trichloroethylene, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene and dichlorobenzene, etc. can be used.

Coating methods include dip coating, spray coating, spinner coating, bead coating,
This can be carried out using a coating method such as a Mayer bar coating method, a blade coating method, 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 a temperature of 30 to 200° C. for a period of from 5 minutes to 2 hours, either in a static state or under blowing air.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. have.

At this time, this charge transport layer may be laminated on or under the charge generation layer.

However, it is desirable that the charge transport layer is laminated on one of the charge generation layers.

The substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive.

The term "electromagnetic waves" as used herein includes a broad definition of "light rays" that includes gamma rays, X-rays, ultraviolet rays, visible light, near infrared rays, infrared rays, far infrared rays, and the like.

When the photosensitive wavelength range of the charge transport layer coincides with or overlaps that of the charge generation layer, charge carriers generated in both trap each other, resulting in a decrease in sensitivity.

When the charge transport material does not have a film formation, a film can be formed by selecting an appropriate binder.

Resins that can be used as binders are, for example, acrylic resins, polyarylates, polyesters, polycarbonates, polystyrene, acrylonitrile-styrene copolymers, acrylonitrile-butadiene copolymers, polyvinyl butyral.

Insulating resins such as polyvinyl formal, polysulfone, polyacrylamide, polyamide, Ill rubber, or poly-N-vinylcarbazole.

Organic photoconductive polymers such as polyvinylanthracene and polyvinylpyrene may be mentioned.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary.

Generally it is 5-301L, but the preferable range is 8-301L.
It is 20 ru.

When forming the charge transport layer by coating T, an appropriate coating method as described above can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a substrate having a conductive layer.

As the substrate having the conductive layer, materials that are conductive themselves such as aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used. In addition, plastics (e.g., polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, Polyfluorinated ethylene, etc.), conductive particles (e.g. carbon black, silver particles, etc.) coated on plastic with a suitable binder, substrates made of plastic or paper impregnated with conductive particles, and plastics with conductive polymers. etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer.

The subbing layer consists of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6).
, nylon 66, nylon 61O1 copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is 0.1 to 40 mm, preferably 0.1 to 40 mm.
Three endings are appropriate.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are laminated in this order, and the charge transport material is made of an electron transporting material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charges, causing attenuation of the surface potential and creating an electrostatic contrast with the unexposed area.

A visible image is obtained by developing the electrostatic latent image thus formed with a negatively charged toner.

This can be directly fixed, or the toner image can be transferred to paper, plastic film, etc. and then developed and fixed.

Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, and then visualized and fixed.

The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones or methods.

On the other hand, when the charge transport material is a hole transport material, the surface of the charge transport layer must be negatively charged.

After charging, when exposed to n-light, holes generated in the charge generation layer in the exposed area are injected into the charge transport layer, and then reach the surface and neutralize the negative charge, resulting in attenuation of about 1 surface cell, and the difference between the exposed area and the unexposed area. An electrostatic contrast occurs between them.

During development, it is necessary to use a positively charged toner, contrary to the case where an electron transport material is used.

The electrophotographic photoreceptor used in the present invention is subject to deterioration due to ultraviolet rays, ozone, etc., dirt due to oil, etc., scratches due to metal chips, etc., damage to the photoreceptor due to photoreceptor contact members such as developing members, transfer members, cleaning members, etc. A protective layer may be further provided on the charge generation layer for the purpose of preventing scratching.

In order to form an electrostatic latent image on this protective layer.

It is desirable that the surface resistivity is 100 or more.

The protective layer used in the present invention is made of polyvinyl butyral, polyester, polycarbonate, acrylic resin, methacrylic resin, nylon, polyimide, polyarylate, polyurethane, styrene-butadiene copolymer, styrene-
It can be formed by applying a solution prepared by dissolving a resin such as an acrylic acid copolymer or a styrene-acrylonitrile copolymer in a suitable organic solvent onto the photosensitive layer and drying it.

Moreover, additives such as ultraviolet absorbers can be added to the resin liquid.

The thickness of the protective layer generally ranges from 0.05 to 20 liters, preferably from 0.2 to 5 watts.

Example 1 Aluminum cylinder] An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia ice cream, 222 ml of water) was coated on the second aluminum cylinder by dip coating method, dried, and the coating amount was 1. A subbing layer of og/m was formed.

Next, 1 part by weight of the charge generating material of structural formula (1), 1 part by weight of butyral resin (Eslec BM-2, manufactured by Sekisui Chemical Co., Ltd.), and 30 parts by weight of isopropyl alcohol were dispersed for 4 hours using a ball mill disperser.

This dispersion was applied onto the previously formed subbing layer by a dip coating method and dried to form a charge generation layer.

The film thickness was 0.3#L.

Next, 1 part by weight of the above-mentioned pyrazoline compound example (1), 1 part by weight of polysulfone (P1700, manufactured by Union Carbide), and 6 parts by weight of monochlorobenzene were mixed,
Wl, one machine melted one.

This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer.

The film thickness was 12 lines.

A corona discharge of 15 KV was applied to the photoreceptor thus prepared.

The surface potential (initial potential vp) at this time was measured.

Furthermore, the surface potential of this photoreceptor was measured after it was left in a dark place for 5 seconds (dark decay Vt). /21ux, gec).

These results were as follows.

Vj: -605V, Vj: 590V, E
1/2:5, 7 lux, sec Examples 2 to 10 The same procedures were carried out except that pyrazoline compound examples (2) to (lO) were used in place of pyrazoline compound example (1) used in Example 1. A photoreceptor was created in exactly the same manner as in Example 1,
The characteristics of this photoreceptor were measured.

These results are shown in Table 1.

Table 1! JJ mouth ■ Va (-V V -V E 1/2 lux
5ec2 (2) 11110800 8.43
(3) 595580 5.84 (4)
590580 5.75 (5) 590575
8.06 (8) 590580 5.9? (
7) 585570 5.88 (13) 80
0585 8.19 (9) 800590 B
, 310 (10) 810800 8.5 Comparative Examples 1 to 6 The following Table 2 was used instead of the pyrazoline compound used in Example 1.
Using the charge transport substances (1) to (8) shown in

Other than that, photoreceptors of Comparative Examples 1 to 6 were produced in exactly the same manner.

Table 2 Transportation jl)lo, Structural formula Table 3 shows the charging characteristics of the photoreceptor described above.

Table 3 1 (1'l 590 585 7.32 (
2) 580 555 7.13 (3)
580 570 7.64 (4) 810 5
90 8.65 (515955857, 8 8 (El) 800 570 7.5 Effects of the Invention As is clear from the results in 1-1), the laminated photoreceptor of the present invention has lower effects than the photoreceptors of Comparative Examples 1 to 6. It can be seen that a photoreceptor with extremely high sensitivity was obtained.

Furthermore, the photoreceptors of Examples 1 to 3 were used as NP manufactured by Canon Co., Ltd.
Image production was repeated 20,000 times using a -1502 copying machine.

As a result, good quality images were obtained even after repeating the test 20,000 times with each photoreceptor, indicating that the photoreceptor of the present invention has extremely excellent durability.

Claims (1)

[Claims] (1) In a laminated electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are provided on a conductive support, the charge generation layer is a polycyclic quinone pigment having the structural formula (1) ▲ Numerical formula, chemical formula, table, etc. ▼(1) A pyrazoline compound whose charge transport layer is represented by the general formula (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) (In the formula, R_1 and R_2 are alkyl groups or a residue that forms a ring with a nitrogen atom, and R_1 and R_2 may be the same or different. 1. An electrophotographic photoreceptor comprising a layer containing a pyridyl group or a quinolyl group.