JPH0469781B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more particularly to a photoreceptor used in a laser planer device.
In particular, the present invention relates to an electrophotographic photoreceptor having high photosensitivity in the oscillation wavelength region of a semiconductor laser. Conventionally, the oscillation wavelength of semiconductor lasers, i.e. 750nm.
As electrophotographic photoreceptors having photoresponsiveness in the near-infrared light region, those using selenium-tellurium-arsenic, cadmium sulfide, or phthalocyanine as photoconductive materials are known. Among these, selenium-tellurium-arsenic and cadmium sulfide have problems in terms of safety for living organisms. On the other hand, phthalocyanine is usually available in the form of a pigment, and has long been known to have photoconductivity, and its suitability for electrophotographic copying machines, electrophotographic engraving machines, or laser printers has been studied. In order to produce a photoreceptor using a phthalocyanine pigment, a film of the phthalocyanine pigment alone, such as a vapor-deposited film, does not fulfill the functions necessary for the photoreceptor. For this purpose, a mixture consisting of a phthalocyanine pigment, an organic resin with film-forming ability, and a dispersion solvent is usually mixed and dispersed using a paint dispersion device, and the resulting photoconductive layer coating liquid is applied onto a conductive support. A photoreceptor is created. Photoreceptors produced in this way have a wide range of spectral sensitivity from the visible region to the near-infrared region, but the sensitivity value itself is not necessarily sufficient, and it has traditionally been difficult to adapt them to high-speed copying machines or laser printers. It was hot. One of the causes of insufficient sensitivity is the induction phenomenon during photodischarge. This is because the potential attenuation immediately after irradiation with light is extremely small, and therefore the energy given to the photoreceptor immediately after irradiation is not used efficiently. In addition, the existence of such an induction phenomenon causes sensitivity changes and potential fluctuations during repeated use.
For this reason, conventional phthalocyanine photoreceptors lack stability and durability in repeated use. In view of the above circumstances, the applicant of the present application has conducted extensive studies with the aim of presenting a phthalocyanine photoreceptor that has high photosensitivity and is excellent in repeated stability and durability. The inventors have discovered that the above object can be achieved by using a composition in which a low-molecular-weight organic compound having a specific structure is uniformly dispersed in molecular form as a binder for a phthalocyanine pigment, and have arrived at the present invention. That is, the object of the present invention described above is to provide at least one phthalocyanine pigment selected from α-type copper phthalocyanine, ε-type copper phthalocyanine, vanadyloxyphthalocyanine, and aluminum chlorinated phthalocyanine on a conductive support, and a pigment of the following general formula ( 1.) An electrophotographic photoreceptor comprising a single-layer photoconductive layer containing an azine compound and an organic resin. General formula () [However, in the formula, R ₁ and R ₃ may be the same or different from each other and represent a hydrogen atom or an alkyl group, and R ₂ and R ₄ may be the same or different from each other and represent at least one nitrogen atom. Represents a heterocyclic group, phenyl group or naphthyl group, which may be substituted with an alkyl group, alkenyl group, alkoxy group or halogen,
Furthermore, at least one of these groups is an electron donating group.

[Formula] (However, R ₅ and R ₆ may be the same or different from each other, and represent a substituted or unsubstituted alkyl group, phenyl group, aryl group, or aralkyl group, and together with the heteroatom, are part of a heterocyclic ring system. ) was achieved. The present invention will be explained in detail below. The applicant of this application has conducted a detailed study on using a composition comprising an organic resin having film-forming ability as a matrix and a low-molecular-weight organic compound uniformly dispersed in molecular form as a binder for phthalocyanine pigments. In a photoreceptor prepared using a composition in which the azine compound represented by the general formula () is uniformly dispersed in molecular form as a binder, the induction phenomenon at the initial stage of photodischarge disappears, and as a result, the induction phenomenon at the initial stage of photodischarge disappears. It has been found that the responsiveness, repeated stability, and repeated durability are significantly improved. The phthalocyanine pigments used in the present invention are α-type copper phthalocyanine, ε-type copper phthalocyanine, vanadyloxyphthalocyanine, and aluminum chlorinated phthalocyanine. These effects are achieved particularly markedly. In the present invention, the symmetrical and asymmetric azines represented by the general formula () are, for example, Houben-Weyl
Author, Methoden der Organichen Chemie.4th edition 10/
Volume 2, pages 89-111, published by Georg ThiemeVerlag.
Synthesized by general known methods of related compounds such as those described in 1967. Among the compounds represented by the general formula (), specific examples suitable for the electrophotographic photoreceptor of the present invention are listed below. The matrix polymer used in the present invention is preferably an organic resin that has excellent compatibility with the azine compound, high electrical insulation, and excellent physical, chemical, and electrical stability. for example,
Polycarbonate, polyarylate, polysulfone, polyethersulfone, phenoxy resin, poly(2.6-dimethyl-1.4-phenylene ether),
Polystyrene, polymethyl methacrylate, polyester resin, polyurethane, polyvinyl chloride,
Polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, styrene-acrylonitrile copolymer,
Examples include vinylidene chloride-acrylonitrile copolymer. These polymers may be used alone or in combination of two or more. The blending ratio of the azine compound represented by the above general formula () to these polymers is
The amount is preferably 10 to 200 parts by weight per 100 parts by weight. In addition, the blending ratio of phthalocyanine pigment is
It is preferably used in an amount of 10 to 200 parts by weight per 100 parts by weight of the polymer. The electrophotographic photoreceptor of the present invention is produced by uniformly dispersing a mixture of a phthalocyanine pigment, an azine compound represented by the general formula (), an organic resin, and a dispersing solvent using a dispersing machine such as a ball mill, attritor, sand mill, kedimir, or three-roll mill. The resulting photoconductive layer coating solution is mixed and dispersed in the coating solution and supported using coating methods such as blade coating, reverse coating, rod coating, gravure coating, knife coating, spray coating, and dip coating. It is created by coating it on the body and letting it dry. The thickness of the photoconductive layer is preferably in the range of 5 to 100 μm, more preferably 10 to 50 μm. Dispersion solvents used for preparing the photoconductive layer coating solution include aromatic hydrocarbons such as benzene, toluene, and xylene, methylene chloride, chloroform, 1.1-dichloroethane, 1.2-dichloroethane, 1.1.2-trichloroethane, and chlorobenzene. Examples include halogenated hydrocarbons, cyclic ethers such as tetrahydrofuran and 1,4-dioxane, ketones such as acetone and 2-butanone, and mixed solvents thereof. In preparing the photoconductive layer coating solution, it is desirable to dissolve the azine compound represented by the general formula () and the organic resin in a dispersion solvent in advance. Suitable conductive supports for the present invention include metal plates such as aluminum, nickel, and chromium, metals such as aluminum, nickel, and palladium, and metal oxides such as tin oxide and indium oxide, such as paper,
Plastic film, glass, etc. vapor-deposited, ion-plated, or sputter-deposited, metal chopsticks such as aluminum bonded to paper or plastic film, etc., organic or inorganic conductive treatment agents, or conductive pigments. Examples include internally added, impregnated or coated paper or plastic film. Further, its shape may be sheet-like, cylindrical, or other shapes. In the present invention, an intermediate layer can be provided between the conductive support and the photoconductive layer. This intermediate layer prevents the injection of free carriers from the conductive support into the photoconductive layer and acts as an adhesive layer to integrally adhere the photoconductive layer to the conductive support. Furthermore, it also has a buffering effect to prevent dielectric breakdown of the photoconductive layer due to corona discharge overcurrent during corona discharge. As the material for this intermediate layer, water-soluble polymer substances such as casein, gelatin, starch, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, hydroxypropyl cellulose, water-soluble polyvinyl butyral, polyacrylic acid, polyethyleneimine, and polyethylene glycol are used. be able to. The thickness of the intermediate layer is suitably in the range of 0.5 to 10 μm. The electrophotographic photoreceptor of the present invention has the above-described structure, and as is clear from the examples described later, it has high sensitivity in the oscillation wavelength range of semiconductor lasers of 750 nm or more, and has an excellent low residual potential. It is something that In addition, there is less fatigue deterioration due to repeated use,
It has stable properties and has excellent repeated durability. Examples of the present invention will be specifically described below, but the embodiments of the present invention are not limited thereby. Example 1 Water-soluble polyvinyl butyral (Eslec W201,
Coating with a 10% aqueous solution of Sekisui Chemical Co., Ltd.)
A 1 μm thick intermediate layer was provided by drying at ℃ for 10 minutes. Next, polycarbonate (Panlite L-1250,
(manufactured by Teijin Kasei Ltd.) was dissolved in 90 parts by weight,
Thereafter, 10 parts by weight of the exemplified compound represented by CA-3 was added and completely dissolved. Then add ε・ to this solution.
Copper phthalocyanine pigment (Lionol Blue)
20 parts by weight of ES (manufactured by Toyo Ink Manufacturing Co., Ltd.) was added, and the mixture was dispersed in a porcelain ball mill for 24 hours. Coating the obtained photoconductive layer coating liquid on the intermediate layer,
It was dried at 140° C. for 5 minutes, and a photoconductive layer with a thickness of 15 μm was provided, thereby producing an electrophotographic photoreceptor of this example. The electrophotographic sensitivity characteristics of this electrophotographic photoreceptor were measured using an electrostatic copying paper tester model SP-428 (manufactured by Kawaguchi Denki Seisakusho Co., Ltd.). That is, the surface of the photoconductive layer of the photoreceptor is charged under the conditions of a corona discharge voltage of +6 KV and a scanning speed of 250 mm/sec, and the potential V ₀ [V] immediately after charging is measured. After dark decay for 5 seconds (potential V ₅ [V]), tungsten light (color temperature
2854 [°K], illuminance 2 [lux]), and the exposure amount (half-reduced exposure amount) required to attenuate the surface potential to V ₅ /2 [V] E ₁₂ [lux・sec] and 30 [lux]・
After irradiation with an exposure amount of [sec], the surface potential V [V] was determined. In addition, a xenon lamp was used as the light source, and λ was obtained by combining it with a Nikon monochromator P-250.
= 790 nm and a light intensity of 0.025 mn/cm ² , and the photosensitivity in monochromatic light was similarly evaluated. The results are shown in Table 1.

[Table] Also, the photosensitivity for monochromatic light of λ = 790nm is 1.9
It was [μJ/cm ² ]. As is clear from the above results, the electrophotographic photoreceptor of this example has sufficient charging ability and charge retention ability, and is also extremely sensitive, with sufficient photosensitivity to the oscillation wavelength of the semiconductor laser. are doing. Example 2 In place of exemplified compound CA-3 in Example 1,
The electrophotographic photoreceptor of this example was produced in the same manner as in Example 1 except that the compounds listed in Table 2 were used. The initial characteristics of these photoreceptors were measured in the same manner as in Example 1, and the results shown in Table 2 were obtained.

[Table] As is clear from the above results, all of the electrophotographic photoreceptors of this example had excellent photoresponsiveness. Example 3 The electrophotographic photoreceptor of this example was produced in the same manner as in Example 1 except that α-type copper phthalocyanine, vanadyloxyphthalocyanine, or aluminum chlorinated phthalocyanine was used in place of ε-type copper phthalocyanine in Example 1. did. The photoreceptor characteristics of these photoreceptors were measured in the same manner as in Example 1, and the results shown in Table 3 were obtained.

[Table] As is clear from the above results, all of the electrophotographic photoreceptors of this example exhibited extremely excellent photoresponsiveness. Example 4 The electrophotographic process of this example was carried out in the same manner as in Example 1, except that vanadyloxyphthalocyanine was used in place of the ε-type copper phthalocyanine in Example 1, and CA-19 was used in place of the exemplified compound CA-3. The body was created. The photoreceptor characteristics of this photoreceptor were measured in the same manner as in Example 1. The same measurement was repeated 10,000 times. The results are shown in Table 4.

[Table] As is clear from the above results, the electrophotographic photoreceptor of this example has extremely excellent photoresponsiveness and repeatability. Comparative Example An electrophotographic photoreceptor of this comparative example was prepared in the same manner as in Example 1 except that a compound represented by the following structural formula was used in place of the exemplified compound CA-3 in Example 1, and the characteristics of the photoreceptor were measured. . The results are shown in Table 5.

[Table] Also, the photosensitivity to monochromatic light of λ = 790nm is 4.0
It was [μJ/cm ² ]. As is clear from the above results, the electrophotographic photoreceptor of this comparative example had significantly poor photoresponsivity.

Claims (1)

[Claims] 1. α-type copper phthalocyanine,
A photoconductive layer consisting of a single layer containing at least one phthalocyanine pigment selected from ε-type copper phthalocyanine, vanadyloxyphthalocyanine, and aluminum chlorinated phthalocyanine, an azine compound represented by the following general formula (), and an organic resin is provided. An electrophotographic photoreceptor characterized by: General formula () [However, in the formula, R ₁ and R ₃ may be the same or different from each other and represent a hydrogen atom or an alkyl group, and R ₂ and R ₄ may be the same or different from each other and represent at least one nitrogen atom. Represents a heterocyclic group, phenyl group or naphthyl group, which may be substituted with an alkyl group, alkenyl group, alkoxy group or halogen,
Furthermore, at least one of these groups is an electron-donating group [Formula] (wherein R ₅ and R ₆ may be the same or different from each other, and are substituted or unsubstituted alkyl groups, phenyl groups, aryl groups, or aralkyl groups. and may be part of a heterocyclic ring system together with a heteroatom).