JPS61189549A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity by incorporating a specified polycyclic quinone type pigment in an electrostatic charge generating layer and a specified pyrazoline deriv. in a charge transfer layer. CONSTITUTION:The charge generating layer can be prepared by coating a conductive substrate with the polycyclic quinone type pigment represented by formula (1) and, when needed,the charge transfer material to be used for the charge transfer layer, that is, a pyrazoline deriv. capable of exhibiting a remarkable effect and represented by formula (2) in which R1, R2 are each alkyl or a residue forming a ring together with an N atom, and optionally same or different, and X is a pyridyl or quinolyl group optionally substd. by at least one alkyl or alkoxy group. The charge transfer layer is electrically connected to the charge generating layer and has a function of receiving charge carriers from the charge generating layer in the presence of an electric field and transferring to the surface. It is preferred to laminate the charge transfer layer on the charge generating layer, and for the charge transfer material to be substantially insensitive to light in the wavelength region of electromagnetic waves to which the charge generating layer is sensitive, thus permitting the photosensitive body high in sensitivity to be obtained.

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. carbazole,
7 Nthracene, pyrazolines, oxadiazoles, hydrazones.

Organic pigments and dyes such as low-molecular organic photoconductors such as polyarylalkanes, phthalocyanine pigments, azo pigments, cyanine pigments, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are used. Are known.

In particular, photoconductive organic pigments and dyes are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has expanded, making it possible to use a large number of photoconductive compounds. 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. It has the advantage of being able to freely control the sensitive wavelength range.

A multilayer photoconductor obtained by laminating a charge transport layer and a charge generation layer mainly composed of a charge generation material has advantages over other single-layer photoconductors in terms of sensitivity and increased residual potential after durability tests. However, it cannot be said that the level is ↓.

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, the present invention is achieved by using a polycyclic 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, the charge generation layer can be added with a -φi sine compound used in the charge transport layer, and the effect becomes even more remarkable.

Further, the charge generation layer used in the present invention can be used as a single layer, or a layer in which a charge generation material and a charge transport material are mixed can 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 comprises 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). 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 laminated electrophotographic photoreceptor of the present invention, the charge generating layer contains as much of the above charge generating material as possible in order to obtain sufficient absorbance, and efficiently injects the generated charge carriers into the charge transport layer. In order to achieve this, it is desirable that the tiIII layer 1 be a thin film layer having a thickness of, for example, less than tog, preferably 0.01 to 1 l.

This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are injected into the charge transport layer without being deactivated by recombination or trapping. This is due to the need to do so.

The charge generation layer can be formed by coating the above-mentioned polycyclic bovine non-based pigment and, if necessary, a charge transporting material together with a suitable binder (or without a binder) on the substrate, or can be formed by vapor deposition using a vacuum evaporation device. It can be obtained by forming a film.

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 formal ,
Insulating resins such as polyvinylpyrrolidone can be mentioned.

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

The solvent that dissolves these resins varies depending on the type of resin, and is 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,
Coating methods such as Mayer bar coating method, blade coating method, roller coating method, and curtain coating method can be used.

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 time ranging from 5 minutes to 2 hours, either stationary or under ventilation.

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 the charge generation layer.

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.

It includes a broad definition of "light ray" that includes radiation, visible light, near infrared rays, infrared rays, far infrared rays, etc.

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 layers trap each other, resulting in a decrease in sensitivity.

When the charge transport material does not have a film formed on it.

Film formation can be achieved by selecting an appropriate binder.

Examples of resins that can be used as binders include acrylic resin, polyarylate, polyester, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, and chlorinated rubber. or poly-N-vinylcarbazole.

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

轡″#-1--23邑涙r441#-小#-To J?+
1 heating m: 4 furnace 1 → 11QIfJ7Jl (Therefore, the film thickness cannot be made thicker than necessary.

Generally it is 5 to 30 l, but the preferred range is 8 to 2
It is 0 judgment.

When forming the charge transport layer by coating, 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 610, 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.
3 is 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 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, causing a decrease in surface potential and creating a gap between the exposed area and the unexposed area. Electrostatic contrast occurs.

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 is generally in the range of 0.05 to 20 JL, preferably 0.2 to 5 p.

Example 1 An ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia 71, 222 ml of water) was coated on an aluminum cylinder using a dip coating method, and dried to give a coating weight of 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 (Nislec BM-2, manufactured by Tsukiki Kagaku ■), 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 generating layer.

The film thickness was 0.3 mm.

Next, 1 part by weight of the above-mentioned pyrazoline compound example (1), 1 part by weight of polysulfone (Pl-700, manufactured by Union Carbide), and 6 parts by weight of monochlorobenzene were mixed, and the seed material was dissolved using an RF stirring machine. .

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 l.

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

The surface potential (initial potential Va) 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 ■).

Sensitivity was evaluated by measuring the amount of exposure (E 1/21ux, 5ec) required to attenuate the potential vj to 1/2 after dark decay.

These results were as follows.

V,: -610V, V,5-: -600V, E
1/2:5, 2 lux, secExamples 2 to 10 Except for using pyrazoline compound examples (2) to (10) in place of pyrazoline compound example (1) used in Example 1, A photoreceptor was prepared in exactly the same manner as in Example 1, and the characteristics of this photoreceptor were measured.

These results are shown in Table 1.

Table 1 LtJ nLLtJ Crest V -V
V -V E 1/2 lux 5ec2
(2) 820810 8.03 (3)
805595 5.44 (4) 810800
5.55 (5) 8005110 5.78
(6) 8055i35 5.8? (7) 5
95585 5.38 (8) 815 [08,
1 9 (9) 820810 8.4' 10 (10) 825815 8.3 Comparative Example 1~
6 The following Table 2 was used instead of the pyrazoline compound used in Example 1.
Photoreceptors of Comparative Examples 1 to 6 were prepared using the charge transport materials (1) to (8) shown in Table 1, but in the same manner as above.

Table 2 Transport substance No. Structural formula Table 3 shows the charging characteristics of the above photoreceptor.

Table 3 1 (1) Eloo 570 7. Q2
(2) 570 550 7.33 (3)
580 555 7.84 (4) 1111
0 590 8.45 (5) 590 570
7゜68 (6) 595 580 7.2 Effects of the Invention As is clear from the above results, the laminated photoreceptor of the present invention has extremely high sensitivity compared to the photoreceptors of Comparative Examples 1 to 6. I can see that it was done.

Furthermore, the photoreceptors of Examples 1 to 3 were used as NP manufactured by Canon Co., Ltd.
Image production was repeated 200 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. X is an unsubstituted pyridyl group, a quinolyl group, or a pyridyl group or a quinolyl group substituted with at least one alkyl group or alkoxy group.