JPH07199499A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To provide a single-layer electrophotographic photoreceptor for digital recordings which has high sensitivity and a good electrophotographic characteristic and is excellent in durability, applicability and cost performance. CONSTITUTION:This electrophotographic photoreceptor has on an electrically conductive support a single photosensitive layer having only gallium halide phthalocyanine dispersed as a photoconductive material in a binding resin. Chlorogallium phthalocyanine having strong diffraction peaks at Bragg angles (2theta+ or -0.2 deg.) of at least 7.4 deg., 16.6 deg., 25.5 deg. and 28.3 deg. to a CuKalpha characteristic X-ray is preferably used as the gallium halide phthalocyanine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member which can be used in electrophotographic printers, copying machines, fax machines and the like.

[0002]

2. Description of the Related Art Heretofore, various inorganic and organic photoconductive substances have been known as photoconductive substances for electrophotographic photoreceptors. The organic photoconductive material has advantages such as transparency of the film, good film forming property, flexibility, no pollution, and low cost when it is used for electrophotography. In recent years, the photosensitive wavelength range of conventionally proposed organic photoconductive materials has been extended to the wavelength of near infrared semiconductor lasers,
There is an increasing demand for use as a photoconductor for digital recording in laser printers, digital copiers, facsimiles and the like, and from this viewpoint, squarerium compounds (Japanese Patent Laid-Open Nos. 49-105536 and 58-21).
No. 416), triphenylamine-based trisazo compounds (JP-A-61-151659), phthalocyanine compounds (JP-A-48-34189 and 57).
No. 14874) has been proposed as an organic photoconductive substance for semiconductor lasers. When an organic photoconductive substance is used as a photosensitive material for a semiconductor laser, first, the photosensitive wavelength range is extended to a long wavelength, then, the sensitivity and durability of the formed photoreceptor are good. Required. In response to these requirements, many reports have been made on the crystal type and electrophotographic characteristics of the phthalocyanine compound, among the above organic photoconductive materials.

On the other hand, in the case of using an organic photoconductive substance, a laminated electrophotographic photoconductor in which a charge generation layer and a charge transport layer are functionally separated has been proposed in order to improve the sensitivity and durability of the photoconductor. ing. As the laminated electrophotographic photoreceptor, a charge generation layer is provided on a conductive support, and various hydrazone compounds, oxazole compounds, triphenylmethane compounds, triarylamine compounds, stilbene compounds, etc. are further typified by the charge generation layer. Negatively charged laminated type photoreceptors provided with a charge transport layer containing a hole transport material have become the mainstream. However, in this negatively charged layered photoreceptor, ozone and nitrogen oxides are generated during the negative charging process by a corona charger, which oxidizes the hole transport material and deteriorates the photoreceptor. It had the drawback of shortening the life of the body. Further, since the negative charges charged on the surface of the photoconductor are unstable, the instability also causes deterioration of resolution and image deletion. In order to solve these problems, addition of an antioxidant, provision of a protective layer, and the like have been proposed, but none have been obtained yet.

On the other hand, development of an electrophotographic photosensitive member by a positive charging system is underway as a device that does not generate ozone or nitrogen oxides during charging. By using the positive charging method,
Since the generation of ozone and nitrogen oxides can be reduced to about 1/10, the durability of the photoconductor can be improved. Further, since the positive charge is stable, the surface of the photoconductor can be uniformly charged with the positive charge, and a photoconductor that forms a high-quality image can be obtained. As the electrophotographic photosensitive member for positive charging, (1) an inverse layer type photosensitive member in which the charge generation layer and the charge transport layer of the negative charging laminated type photosensitive member are reversely configured, and (2) charges on a conductive support. A charge-transporting laminated type photoreceptor having a charge-generating layer and a charge-transporting layer containing a charge-transporting material thereon, (3) a charge-generating material and a hole-transporting material in a binder resin on a conductive support. There are three types of single-layer type photoconductors that are dispersed in. The reverse layer type photoreceptor of (1) has a problem in durability because the charge generating layer, which essentially needs to be thin, is provided on the surface of the photoreceptor. Further, since it has a two-layer structure, there is a problem that the manufacturing process is complicated, the yield is deteriorated, and the manufacturing cost is increased. The charge-transporting laminated type photoreceptor of (2) has a problem that a stable charge-transporting material having a high charge-transporting ability has not yet been developed, and that the two-layer structure complicates the manufacturing process and increases the manufacturing cost. Has the problem of becoming. The single-layer type photoconductor (3) has a problem that it has lower sensitivity, a larger residual potential, and poor cycle stability as compared with the negatively charged layered photoconductor. It is considered that this is because charge generation and transfer occur randomly in the monolayer, and charge recombination is unavoidable.

[0005]

Among these three types, if the improvement of the sensitivity, residual potential and cycle stability, which are the problems of the single-layer type photoconductor of (3), can be realized, the durability, It is considered that an ideal photoconductor that satisfies all coatability, manufacturing cost and all the characteristics of the electrophotographic photoconductor will be completed. Therefore, realization of such an electrophotographic photoconductor is required. The present invention has been made for the purpose of solving the drawbacks of the single-layer type electrophotographic photosensitive member as described above. That is, an object of the present invention is to provide a single-layer type electrophotographic photoreceptor for digital recording, which has high sensitivity and good electrophotographic characteristics, and is excellent in durability, coatability, and cost. .

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies on the characteristics of various phthalocyanine compounds as a single-layer type electrophotographic photoreceptor, and as a result, halogenated gallium phthalocyanine has a charge generation function and a charge transport function. It is noted that the inclusion of halogenated gallium phthalocyanine in the single-layer type photosensitive layer improves the sensitivity, residual potential and cycle stability, which are problems of the conventional single-layer type photosensitive layer, and is excellent. The present invention has been completed and the present invention has been completed. That is, the electrophotographic photosensitive member of the present invention is characterized by having a photosensitive layer having a single-layer structure in which only a halogenated gallium phthalocyanine is dispersed as a photoconductive material in a binder resin on a conductive support. . In the present invention, as the halogenated gallium phthalocyanine, at least 7.4 ° and 16.6 of the Bragg angle (2θ ± 0.2 °) with respect to the CuKα characteristic X-ray are used.
Chlorogallium phthalocyanine having strong diffraction peaks at °, 25.5 ° and 28.3 ° is preferably used.

The present invention will be described in detail below. The halogenated gallium phthalocyanine used in the present invention is represented by the following general formula (I).

[Chemical 1] (In the formula, X ¹ represents a halogen atom, and X ² , X ³ , X
⁴ and X ⁵ each represent a hydrogen atom, a halogen atom, an alkyl group or an aryloxy group, and a, b, c
And d each represent an integer of 0 to 4. )

Various methods can be used for synthesizing the halogenated gallium phthalocyanine used in the present invention. An example of synthesizing chlorogallium phthalocyanine will be shown below. First, by condensing 1,3-diiminoisoindoline and gallium trichloride in quinoline, at least 11.0 ° of Bragg angle (2θ ± 0.2 °) to CuKα characteristic X-ray, 13.
Chlorogallium phthalocyanine having strong diffraction peaks at 5 ° and 27.1 ° is obtained. This chlorogallium phthalocyanine is dry-milled using a mill such as a vibration mill, an automatic mortar, a sand mill, an attritor, or a ball mill, and then a suitable solvent such as benzyl alcohol, isopropyl alcohol, cyclohexanone, toluene, butyl acetate or dimethyl sulfoxide. At least 7.4 °, 16.6 °, 25.5 ° and 28.3 of the Bragg angle (2θ ± 0.2 °) with respect to the CuKα characteristic X-rays are obtained by wet pulverizing using the pulverizing device. It is possible to obtain chlorogallium phthalocyanine having a strong diffraction peak at °.

On the other hand, as the binder resin in the present invention,
Any known material can be used. For example, polycarbonate resin, polysulfone resin,
Polyarylate resin, polystyrene resin, polyester resin, methacrylic acid ester polymer, styrene-acrylonitrile copolymer, styrene-methacrylic acid ester copolymer, polyvinyl butyral resin, polyolefin resin, polyacetal resin, polyamide resin, vinyl acetate polymer, Examples thereof include vinyl chloride-vinyl acetate copolymer, cellulose ester resin, cellulose ether resin, polybutadiene resin, polyurethane resin, epoxy resin and the like. These binder resins can be used alone or as a mixture of two or more kinds. The compounding ratio of the gallium phthalocyanine halide and the binder resin is 1:10 to 10 :.
It is 10, preferably 1:10 to 7:10. If the proportion of gallium phthalocyanine halide is too high,
The mechanical strength is lowered, the durability is deteriorated, the electrification property and the stability of the coating solution are lowered, and if it is too low, the sensitivity is lowered, so that the above range is preferable.

As the solvent used for dispersion, methanol, ethanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone,
Methyl ethyl ketone, cyclohexanone, methyl acetate,
Examples thereof include organic solvents such as ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, benzene, toluene, xylene, chlorobenzene, dimethylformamide, dimethylacetamide, dimethylsulfoxide, and mixed solvents thereof. As a dispersing means, a method such as a sand mill, a colloid mill, an attritor, a ball mill, a dyno mill, a co-ball mill or a roll mill can be used. As a coating method, a blade coating method, a wire bar coating method,
A method such as a spray coating method, a dip coating method, a bead coating method and a curtain coating method can be used. The thickness of the photosensitive layer is 1 to 50 μm,
The range of 5 to 40 μm is preferable.

In the present invention, any conductive support can be used as long as it is used in an electrophotographic photoreceptor. Further, if necessary, the surface of the conductive support can be subjected to various treatments within a range that does not affect the image quality. For example, surface anodizing treatment, surface roughening treatment by liquid honing, chemical treatment,
Coloring treatment or the like can be performed. Further, the electrophotographic photoreceptor of the present invention may be provided with an undercoat layer between the photosensitive layer and the substrate, if necessary. The undercoat layer is effective for preventing unnecessary injection of electric charges from the substrate, and has the function of increasing the chargeability of the photoconductor. Further, it also has the function of improving the adhesiveness between the photosensitive layer and the substrate. Further, the electrophotographic photosensitive member of the present invention may be provided with a protective layer on the photosensitive layer in order to improve printing durability.

[0012]

The halogenated gallium phthalocyanine is an organic pigment which has not only an excellent charge generating function but also a charge transporting function and a function of transporting both electrons and holes as its characteristics. Therefore, the single-layer type photoconductor provided with the photosensitive layer in which the halogenated galimphthalocyanine is dispersed in the binder resin has excellent characteristics that the conventional single-layer photoconductor does not have. That is, (1) a single layer structure simplifies the manufacturing process, (2) has excellent durability, (3)
Higher sensitivity than conventional single-layer type photoreceptors, (4) low residual potential, (5) excellent chargeability, (6) halogenated gallium phthalocyanine transports both electrons and holes. Since it has a function, it can be used for both the positive charging method and the negative charging method. (7) In particular, it has excellent characteristics in the positive charging method. The electrophotographic photosensitive member of the present invention is effectively used in an electrophotographic copying machine, but is also applicable to a laser beam printer, an LED printer, a CRT printer, a microfilm reader, a plain paper facsimile, an electrophotographic plate making system, and the like. Is.

[0013]

The present invention will be described in more detail with reference to the following examples. In the examples, "part" means "part by weight".
Means (Preparation Example of Chlorogallium Phthalocyanine) Preparation Example 1 30 parts of 1,3-diiminoisoindoline and 9.1 parts of gallium trichloride were placed in 230 parts of quinoline and heated to 200 ° C.
After reacting for 3 hours at room temperature, the product is filtered off, N, N
After washing with dimethylformamide and methanol and then drying the wet cake, 28 parts of chlorogallium phthalocyanine crystals were obtained. The powder X-ray diffraction pattern of the obtained chlorogallium phthalocyanine crystal is shown in FIG.

Preparation Example 2 28 parts of the chlorogallium phthalocyanine crystal obtained in Preparation Example 1 was placed in an automatic mortar (Lab Mill UT-21).
Type, manufactured by Yamato Scientific Co., Ltd.) for 3 hours. The powder X-ray diffraction pattern of the obtained chlorogallium phthalocyanine crystal is shown in FIG. Preparation Example 3 3 parts of the chlorogallium phthalocyanine crystal obtained in Preparation Example 2 was ball-milled at room temperature for 24 hours in 20 parts of benzyl alcohol together with 60 parts of 1 mmφ glass beads, washed with 5000 parts of methanol, and then filtered. Then, crystals of chlorogallium phthalocyanine were obtained. The powder X-ray diffraction pattern of the obtained chlorogallium phthalocyanine crystal is shown in FIG. The maximum absorption wavelength of the chlorogallium phthalocyanine crystal obtained here is 780 nm.

Example 1 2 parts of the chlorogallium phthalocyanine obtained in Preparation Example 3 was added to a solution prepared by dissolving 10 parts of polycarbonate Z resin (Iupilon Z-400, manufactured by Mitsubishi Gas Chemical Co., Inc.) in 90 parts of toluene in advance. The mixture was dispersed in a sand mill for 24 hours to prepare a photosensitive layer coating solution in which the weight ratio of chlorogallium phthalocyanine and polycarbonate Z resin was 2:10. The obtained coating liquid was applied on an aluminum sheet having a thickness of 50 μm by a dip coating device and dried by heating at 100 ° C. for 60 minutes to form a photosensitive layer having a thickness of 15 μm. Examples 2 to 5 In Example 1, the weight ratio of chlorogallium phthalocyanine to polycartonate Z resin was 0.5: 10, respectively.
(Example 2), 1:10 (Example 3), 10:10 (Example 4) and 15:10 (Example 5), except that the photosensitive layer coating solution was prepared. An electrophotographic photosensitive member was produced in the same manner as above.

Comparative Example 1 The procedure of Example 1 was repeated except that 2 parts of X-type metal-free phthalocyanine was used in place of chlorogallium phthalocyanine.
An electrophotographic photosensitive member was produced in the same manner as in Example 1. Comparative Example 2 To a solution prepared by dissolving 10 parts of the polycarbonate Z resin used in Example 1 in 90 parts of toluene in advance, 2 parts of the chlorogallium phthalocyanine obtained in Preparation Example 3 was added, and the mixture was dispersed by a sand mill for 24 hours, and then charge transport was performed. As a material, 1 part of a compound represented by the following structural formula (II) was added and kneaded to prepare a photosensitive layer coating liquid having a weight ratio of chlorogallium phthalocyanine, a charge transporting material and a polycarbonate Z resin of 2: 1: 10. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the obtained coating liquid was used.

[Chemical 2]

The characteristic evaluation test of the electrophotographic photosensitive members prepared in the above-mentioned Examples and Comparative Examples was conducted as follows.
Using an electrostatic copying paper tester (Electrostatic Analyzer EPA8100, manufactured by Kawaguchi Electric Co., Ltd.), 2
After positively charging the photoconductor by corona discharge of +5.5 kV in the environment of 0 ° C and 50% RH, the light of the tungsten lamp is split into monochromatic light of 780 nm by using a monochromator, and the photoconductor surface The irradiation was adjusted to 1 μW / cm ² . Initial surface potential V0 at that time
(V) and the half-exposure amount E1 / until it becomes 1/2 of V0
2 (erg / cm ² ) was measured, and then 10 lux of tungsten light was irradiated on the surface of the photoconductor for 1 second to measure the residual potential VR (V). Further, after repeating the above charging and exposure 1000 times, V0, E1 / 2 and VR
Was measured. The results are shown in Table 1. Further, instead of the polarity of the corona discharge, is negatively charge the photosensitive member by corona discharge -5.5KV, was measured half decay exposure ^{E1 / 2 (erg / cm 2} ) when irradiated with monochromatic light of the 780nm .
The results are shown in Table 1.

[0018]

[Table 1]

[0019]

As described above, the electrophotographic photoreceptor of the present invention has the drawbacks of the conventional single-layer type photoreceptor such as sensitivity, residual potential,
It also has good electrophotographic characteristics by improving the problem of cycle stability, and has high sensitivity, low residual potential, excellent cycle stability, and durability and coating property especially in the positive charging system. It has the effect of being excellent in terms of workability and cost.

[Brief description of drawings]

FIG. 1 shows a powder X-ray diffraction diagram of a chlorogallium phthalocyanine crystal obtained in Preparation Example 1.

FIG. 2 shows a powder X-ray diffraction diagram of a chlorogallium phthalocyanine crystal obtained in Preparation Example 2.

FIG. 3 shows a powder X-ray diffraction pattern of the chlorogallium phthalocyanine crystal obtained in Preparation Example 3.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer having a single layer structure in which only a gallium phthalocyanine halide is dispersed as a photoconductive material in a binder resin on a conductive support.