JPH0219944B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to a novel electrophotographic photoreceptor having a photosensitive layer containing a carrier-generating substance and a carrier-transporting substance. [Background of the Invention] Conventionally, electrophotographic photoreceptors having a photosensitive layer containing an inorganic photoconductor such as selenium, zinc oxide, or cadmium sulfide as a main component have been widely known. However, these are not necessarily satisfactory in terms of properties such as thermal stability and durability, and furthermore, there are problems in manufacturing and handling due to toxicity. On the other hand, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, inexpensive, and easy to handle, and generally compared to selenium photoreceptors. It has many advantages, including excellent thermal stability, and has attracted a lot of attention in recent years. Poly-N-vinylcarbazole is the most well-known such organic photoconductive compound, and a charge transfer complex formed from poly-N-vinylcarbazole and a Lewis acid such as 2,4,7-trinitro-9-fluorenone is Electrophotographic photoreceptors having a photosensitive layer as a main component have already been put into practical use. On the other hand, electrophotographic photoreceptors are known that have a laminated type or dispersion type functionally separated photosensitive layer in which the carrier generation function and the carrier transport function of the photoconductor are respectively assigned to separate substances. Electrophotographic photoreceptors having a photosensitive layer consisting of a carrier generation layer consisting of a thin amorphous selenium layer and a carrier transport layer containing poly-N-vinylcarbazole as a main component have already been put to practical use. However, since poly-N-vinylcarbazole lacks flexibility, its coating is hard and brittle, and is prone to cracking and peeling. Therefore, electrophotographic photoreceptors using it have poor durability. inferior,
In addition, if a plasticizer is added to improve this drawback, the residual potential increases when subjected to the electrophotographic process, and as it is repeatedly used, the residual potential accumulates and gradually fogs appear in the copied image. has. In addition, since low-molecular organic photoconductive compounds generally do not have film-forming ability, they are used in combination with any binder, and the physical properties of the film can be adjusted by selecting the type and composition ratio of the binder used. However, the types of organic photoconductive compounds that have high compatibility with binders are limited, and in reality they cannot be used in electrophotographic photoreceptors. There are not many materials that can be used in the construction of the photosensitive layer. For example, 2,5-bis(p-diethylaminophenyl)-
1,3,4-oxadiazole has low compatibility with binders that are usually preferably used as materials for the photosensitive layer of electrophotographic photoreceptors, and has favorable electrophotographic properties with binders such as polyester and polycarbonate. When a photosensitive layer is formed by mixing in the proportions required to obtain oxadiazole, crystals of oxadiazole will precipitate at a temperature of 50°C or higher, resulting in a decrease in electrophotographic properties such as charge retention and sensitivity. have On the other hand, the diarylalkane derivatives described in U.S. Pat. When used in the construction of a photosensitive layer of a photographic photoreceptor, it has the disadvantage that the sensitivity of the photosensitive layer gradually decreases. On the other hand, in recent years, electrophotography has been actively applied as a printer. This is based on the fact that electrophotography is non-impact, generates little noise, is fast, and has relatively high resolution. However, when using electrophotography as a printer, there are disadvantages in that the light source, such as a laser or OFT (optical fiber tube), is expensive and occupies a large space of the device. Therefore, it is desirable to use a semiconductor laser as the light source in order to make the device smaller and cheaper. However, the oscillation wavelength of a practical semiconductor laser is
At present, an organic photoconductive compound having sufficient sensitivity in this region of 750 nm or more has not yet been found. [Object of the Invention] An object of the present invention is to provide an electrophotographic photoreceptor that is highly sensitive and has a low residual potential in the oscillation wavelength region of a semiconductor laser, that is, 750 nm or more. Another object of the present invention is to reduce fatigue deterioration due to repeated use of a photoreceptor for repetitive transfer type electrophotography in which charging, exposure, development, and transfer processes are repeated, and to provide durability with stable characteristics over a long period of time. An object of the present invention is to provide an electrophotographic photoreceptor with excellent properties. [Structure of the Invention] In order to achieve the above object, the inventors of the present invention have conducted extensive research to develop a functionally separated electronic device comprising a photosensitive layer containing a carrier-generating substance and a carrier-transporting substance provided on a conductive support. The photographic photoreceptor contains at least one type of phthalocyanine pigment represented by the following general formula [] as a carrier generating substance,
It has been found that the object can be achieved by using an electrophotographic photoreceptor containing at least one type of amine derivative represented by the following general formula [] as a carrier transport material in a photosensitive layer having a laminated or single layer structure. General formula [] (C ₈ H ₄ N ₂ ) ₄ Rn In the formula, R is a hydrogen atom, deuterium, sodium, potassium, copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminum, gallium, Indium, lanthanum, neodymium, samarium, europium, dysprosium, holmium, erbium, thulium, ytterbium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt, nickel, rhodium, palladium, osmium and platinum, n is 0-2
It is. Among these, alpha (α), beta (β),
Gamma (γ), pi (π), x (x), epsilon (ε) type metal-free phthalocyanines or metal phthalocyanines such as copper, nickel, cobalt, lead, zinc, aluminum and aluminum chlorinated phthalocyanines are preferred, especially x (x)
and apron (ε) type metal-free phthalocyanines or copper, aluminum and aluminum chlorinated phthalocyanines are preferred. These phthalocyanine pigments include the compounds represented by the general formula [], for example,
No. 40-2780, Special Publication No. 8102, Special Publication No. 1977-
No. 11021, Special Publication No. 46-42511, Special Publication No. 46-42512
No. 48-163, Japanese Patent Publication No. 49-17535, Japanese Patent Publication No. 5059-1982, and Japanese Patent Publication No. 38543-1983. General formula [] In the formula, X ₁ and X ₂ may be the same or different,
Each represents a substituted or unsubstituted phenyl group. X ₃ represents a substituted or unsubstituted arylene group. X ₄ is replaced,
3 unsubstituted aryl groups, furyl groups, and thienyl groups
It represents any of the following groups, and is used as a substituent in combination of one or more from the group consisting of an alkyl group, an alkoxy group, an aryloxy group, and a halogen atom. Preferred substituents for X ₁ , X ₂ and X ₃ include a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, a substituted or unsubstituted amino group, or an aryloxy group. That is, in the present invention, the general formula []
By combining the phthalocyanine pigment represented by the formula and the amine derivative represented by the general formula [],
As a so-called functionally separated electrophotographic photoreceptor, in which carrier generation and transport are performed using separate substances,
It has excellent coating physical properties, and has excellent properties such as charge retention, sensitivity, and residual potential.The above properties do not change even when exposed to heat or light, and it has stable properties.It also has the same oscillation wavelength as a semiconductor laser. It is possible to produce an electrophotographic photoreceptor that is highly sensitive to 750 nm. Specific examples of the amine derivatives useful in the present invention represented by the above general formula [] include those having the following structural formula, but the amine derivatives of the present invention are not limited thereto. . Exemplary compound The above triarylamine derivatives A-(1) to A-(21) can be easily synthesized by known methods. For example, Organic React
ions vol.25p.73 (John Wiley & Sons, Inc.), an aromatic aldehyde represented by the following general formula [] and a dialkyl phosphonate represented by the following general formula [] are mixed with N,N-dimethylformamide or the like. It can be easily obtained by condensation in a solvent in the presence of a base such as sodium alkoxide or sodium hydride. Here, X ₁ , X ₂ , X ₃ , and X ₄ have the same meanings as in the general formula [], and R' represents an alkyl group or an aryl group. Among the amine derivatives exemplified above, especially A-
(5), A-(6) triarylamine derivatives are effective. Since the phthalocyanine pigment, which is the carrier generating substance in the present invention, does not have film-forming ability by itself, a binder must be used when the carrier generating layer is formed as the upper layer of the two-layer photoreceptor.
Preferably used binders include phenolic resins, polyester resins, vinyl acetate resins, polycarbonate resins, polypeptide resins,
Cellulose resin, polyvinylpyrrolidone, polyethylene oxide, polyvinyl chloride resin, starch, polyvinyl alcohol, acrylic copolymer resin, methacrylic copolymer resin, silicone resin, polyacrylonyl copolymer resin, polyacrylamide, polyvinyl Examples include butyral, but p-octylphenol formaldehyde resin described in Japanese Patent Publication No. 13938/1986 is particularly preferred. Furthermore, since the amine derivative which is the carrier transport substance in the present invention similarly does not have film-forming ability, when forming a photosensitive layer using this, it is preferable to use it together with a binder. Preferred binders are hydrophobic, high dielectric constant, electrically insulating film-forming polymers. Such polymers include polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride,
Polystyrene, polyvinyl acetate, styrene-butadiene copolymer, vinylidene chloride acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol Examples include formaldehyde resin, styrene-alkyd resin, etc., but are not limited to these, of course. These binders may be used alone or in combination of two or more. Furthermore, organic semiconductors such as poly-N-vinylcarbazole, oxazole derivatives, oxadiazole derivatives, and triphenylmethane derivatives can also be added to the carrier transport layer together with the carrier transport substance. Among these, poly-N-vinylcarbazole has the ability to form a film by itself, and when it is added, there is no need to use other binders, which is particularly preferred. As shown in FIGS. 1 and 2, the photoreceptor of the present invention has a carrier generating layer 2 containing a phthalocyanine pigment, which is a carrier generating substance in the present invention, as a main component on a conductive support 1, and The photosensitive layer 4 may be in the form of a laminate with a carrier transport layer 3 whose main component is an amine derivative as a transport substance. As shown in FIGS. 3 and 4, this photosensitive layer 4 may be provided on the conductive support 1 with an intermediate layer 5 interposed therebetween. When the photosensitive layer 4 has a two-layer structure in this manner, a photoreceptor having the most excellent electrophotographic properties can be obtained. Further, in the present invention, as shown in FIGS. 5 and 6, the photosensitive layer 4 is formed by dispersing a carrier generating substance 7 in the form of fine particles in a layer 6 mainly composed of the carrier transporting substance. directly on the sexual support,
Alternatively, it may be provided via the intermediate layer 5. Here, when the photosensitive layer 4 has a two-layer structure, which of the carrier generation layer 2 and the carrier transport layer 3 is to be the upper layer is determined depending on whether the charging polarity is positive or negative. In other words, when used with negative charge,
It is advantageous for the carrier transport layer 3 to be the upper layer,
This is because the amine derivative of the present invention in the carrier transport layer is a substance that has a high ability to transport holes. The carrier generation layer 2 constituting the two-layered photosensitive layer 4 may be formed directly on the conductive support 1 or the carrier transport layer 3, or provided with an intermediate layer such as an adhesive layer or a barrier layer as necessary. In addition, it can be formed by the following method. (M-1) Vacuum deposition method (M-2) Method of dissolving the carrier-generating substance in a suitable solvent and applying it (M-3) Using a ball mill, homomixer, sand mill, colloid mill, etc., the carrier-generating substance is applied as a dispersion medium. A method of applying a dispersion obtained by forming fine particles and mixing and dispersing them with a binder if necessary.Thickness of the carrier generation layer 2 in which the phthalocyanine pigment formed in this way is used as a carrier generation substance. is preferably 0.01 to 5 microns, more preferably 0.05 to 3 microns. Further, the thickness of the carrier transport layer 3 can be changed as necessary, but it is usually preferably 5 to 30 microns. The composition ratio in this carrier transport layer 3 is preferably 0.8 to 10 parts by weight of the binder to 1 part by weight of the carrier transport material whose main component is the amine derivative described above. When forming the photosensitive layer 4 in which the substance phthalocyanine pigment is dispersed, the carrier generating substance 1
It is preferable to use the binder in an amount of 5 parts by weight or less based on the weight part. Further, when the carrier generating layer 2 is configured as a dispersed type layer using a binder, it is preferable to use the binder in an amount of 5 parts by weight or less per 1 part by weight of the carrier generating substance. The conductive support 1 used in the construction of the electrophotographic photoreceptor of the present invention is a metal plate, or a conductive compound such as a conductive polymer or indium oxide, or a thin layer of a metal such as aluminum, palladium, or gold coated thereon. , paper, plastic film, etc. that have been vapor-deposited or laminated to provide conductivity are used. In addition to the polymer used as the binder, the intermediate layer 5 such as an adhesive layer or barrier layer may be made of an organic polymer such as gelatin, casein, starch, polyvinyl alcohol, vinyl acetate, ethyl cellulose, carboxymethyl cellulose, or the like. Aluminum oxide or the like is used. 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. Further, another object of the present invention, which is to provide an electrophotographic photoreceptor with excellent durability and less fatigue deterioration due to repeated use and having stable characteristics, will be apparent from the Examples described below. [Example] Hereinafter, the present invention will be specifically explained using Examples.
This does not limit the embodiments of the present invention. Example 1 Exemplary compound A was placed on a grained, anodized and sealed aluminum plate with a thickness of about 0.25 mm.
- (6), 6 parts by weight and 10 parts by weight of polycarbonate "Panlite L-1250" (manufactured by Teijin Chemicals), 1,
It was dissolved in 90 parts by weight of 2-dichloroethane, and this solution was applied to a film thickness of 11 microns after drying to form a carrier transport layer. After drying this for about 30 minutes in a dryer heated to 90°C, 4 parts by weight of washed ε-type copper phthalocyanine and 1 weight of p-octylphenol formaldehyde resin (manufactured by Gunei Kagaku Co., Ltd.) are added on top of this as a carrier generating substance. A carrier generating layer is formed by dispersing a composition consisting of 120 parts by weight of methyl ethyl ketone and 120 parts by weight of methyl ethyl ketone for 30 minutes using glass beads, and applying it with a wire bar to a dry film thickness of about 0.5 μm. The body was created. The electrophotographic properties of this electrophotographic photoreceptor were measured by a dynamic method using an electrostatic copying paper tester "SP-428 model" (manufactured by Kawaguchi Electric Seisakusho).
That is, the surface of the photosensitive layer of the photoreceptor is charged with a + voltage.
Surface potential VA when charged at 6.0kv for 5 seconds,
Next, the photoreceptor surface is irradiated with light from a tungsten lamp so that the illumination intensity is 351ux, and the exposure amount required to attenuate the surface potential VA by half (half-reduced exposure amount) E1/2 (lux・sec) and 30lux・sec.
Surface potential (residual potential) after irradiation with an exposure dose of sec
We each asked for VR. In addition, a Xe lamp was used as a light source, monochromatic light was extracted in the range of 400 to 880 nm using a Nikon monochromator P-250, and the light intensity was set to 0.020 mW/cm ² and the surface of the photoreceptor was similarly irradiated to obtain the spectral sensitivity (half exposure amount). ) was sought. The results are shown in Table 1.

[Table] As is clear from Table 1, the electrophotographic photoreceptor of the present invention has sufficient charge retention ability and high sensitivity. Also, the sensitivity to monochromatic light of 790nm is
It was 2.0μJ/ ^cm2 . Comparative Example 1 A comparative photoreceptor was prepared in the same manner as in Example 1, except that 2-(p-diethylamino)benzothiazole having the following structural formula was used instead of Exemplified Compound A-(6) as a carrier transport substance. did. When this photoreceptor was measured in the same manner as in Example 1, the results shown in Table 2 were obtained.

[Table] Also, the sensitivity for 790nm monochromatic light is 6.1μJ/
It was warm in ^cm2 . Comparative Example 2 A comparative photoreceptor was prepared in the same manner as in Example 1, except that dibromoviolanthrone having the following structural formula was used in place of the carrier generating substance in Example 1. When the same measurements as in Example 1 were performed on this photoreceptor, the results shown in Table 3 were obtained.

[Table] As is clear from the above results, the sensitivity of the comparative photoreceptor was significantly inferior to that of Example 1 of the present invention.

[Brief explanation of drawings]

1 to 6 are cross-sectional views of examples of the layer structure of the electrophotographic photoreceptor of the present invention, respectively. 1... Conductive support, 2... Carrier generation layer, 3...
Carrier transport layer, 4... Photosensitive layer, 5... Intermediate layer, 6...
A layer containing a carrier transport substance, 7... a carrier generation substance.

Claims (1)

[Scope of Claims] 1. In a functionally separated electrophotographic photoreceptor comprising a conductive support and a photosensitive layer containing a carrier-generating substance and a carrier-transporting substance, the carrier-generating substance may be a compound represented by the following general formula []. When the photosensitive layer contains the phthalocyanine pigment shown and has a laminated structure of a carrier generation layer and a carrier transport layer, fine particles of the carrier generation substance are added to the layer mainly composed of the carrier transport substance as the carrier transport substance. An electrophotographic photoreceptor characterized in that a dispersed single-layer photosensitive layer contains a triarylamine derivative represented by the following general formula [] as a carrier transport substance. General formula [] (C ₈ H ₄ N ₂ ) ₄ Rn [In the formula, R is a hydrogen atom, deuterium, sodium, potassium, copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminum, gallium , indium, lanthanum, neodymium, samarium, europium, dysprosium, holmium, erbium, thulium, ytterbium, vanadium, antimony, chromium, molybdenum, uranium, manganese, iron, cobalt, nickel, rhodium, palladium, osmium and platinum, n is 0-2
It is. ] General formula [ ] [In the formula, X ₁ and X ₂ may be the same or different,
Represents a substituted or unsubstituted phenyl group, X ₃ is substituted,
It represents an unsubstituted arylene group, and X ₄ represents any of the following three groups: substituted or unsubstituted aryl, _furyl , or thienyl group. , halogen atoms in combination. ]