JPH0727244B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an electrophotographic photoreceptor, and more specifically,
The present invention relates to an electrophotographic photoconductor having excellent exposure photosensitivity and wavelength properties.

(Prior Art) Conventionally, as a photoreceptor of an electrophotographic photoreceptor, one using an inorganic photoconductor such as selenium, a selenium alloy, zinc oxide, cadmium sulfide, and tellurium has been mainly used.
In recent years, the development of semiconductor lasers has been remarkable, and small, stable laser oscillators have become available at low cost, and they are beginning to be used as light sources for electrophotography. However, using a semiconductor laser that oscillates short-wavelength light in these devices has many problems in terms of life, output, and the like. Therefore, it is unsuitable to use the material which has been used conventionally for the short wavelength region for the semiconductor laser, and it is not suitable for the long wavelength region (780n
It has become necessary to study materials with high sensitivity to (m or more). Recently, research has been actively conducted on a laminated organic photoconductor in which an organic material, particularly phthalocyanine, which is expected to have sensitivity in a long wavelength region, is used and laminated.
As a phthalocyanine (Pc) -based material with high sensitivity in the long wavelength region, ε-type copper phthalocyanine (ε-CuPc), X has already been used.
Type metal-free phthalocyanine (X-H2Pc) and τ type metal-free phthalocyanine (τ-H2Pc) are known, but an electrophotographic photoreceptor formed by combining with a conventional charge transfer agent is
There were problems with sensitivity, stability after repeated use, and photomemory properties, and it was not at a sufficient level for actual use.

(Problems to be Solved by the Invention) An object of the present invention is to provide an electrophotographic photoreceptor having excellent exposure sensitivity characteristics, high sensitivity in a long wavelength region of 780 nm or more, stable upon repeated use, and good photomemory property. To get.

[Structure of Invention]

(Means and Actions for Solving Problems) The above-mentioned object is to use a titanium phthalocyanine compound represented by the general formula [I] as a charge generating agent on a conductive support and to use a general formula as a charge transfer agent. This is achieved by the electrophotographic photoreceptor of the present invention, which is characterized by using the compound represented by [II].

The titanium phthalocyanine compound used in the present invention is a “phthalocyanine compound” (Mo
ser and Thomas "Phthalocyanine Compounds"), USP3825422, JP-A-59-49544, JP-A-59-1669.
59, JP-A-61-109056, JP-A-61-171771, JP-A-61-217050 and JP-A-61-239248, or any other known method may be used. .
The titanium phthalocyanine-based compound is represented by the general formula [I], and may have any crystal state and substituents as long as titanium is coordinated to the central nucleus of phthalocyanine. In addition, the X-ray diffraction pattern is not affected by the type and number of substituents, and does not differ depending on the crystalline state.

(In the formula, R ₁ represents a halogen atom, an oxygen atom or an alkoxy group, R ₂ , R ₃ , R ₄ and R ₅ represent a hydrogen atom, a halogen atom,
Represents a substituent such as an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a nitro group, a cyano group, a hydroxyl group, a benzyloxy group, and an amino group, and j is an integer of 1 or 2,
k, l, m and n represent an integer of 0-4. The charge transfer agent is a compound represented by the general formula [II].

(In the formula, R ₆ and R ₇ are a hydrogen atom, an alkyl group, an alkoxy group and an aryl group, and R ₈ , R ₉ and R ₁₀ are a hydrogen atom or -NR
₆ (R ₇ ) group is shown, and n is 0 or 1. A particularly preferred example of the general formula [II] is a compound in which R ₆ and R ₇ are both ethyl groups and R _{8 to} R ₁₀ are hydrogen atoms, or any one of R _{8 to} R ₁₀ is -NC ₂ It is a compound that is H ₅ (C ₂ H ₅ ).

It is desirable that the photoconductor has an undercoat layer, a charge generation layer, and a charge transfer layer stacked in this order on a conductive substrate because of high sensitivity. However, the undercoat layer, the charge transfer layer, and the charge generation layer are in this order. It is also possible to use a layered structure in which the charge generation agent and the charge transfer agent are dispersed in a suitable resin on the undercoat layer to form a single layer.

If necessary, the undercoat layer may be removed, or a resin or an inorganic compound may be provided on the uppermost layer as an overcoat layer.

The charge generation layer is formed by a vapor deposition method or a dispersion coating method.

The vapor deposition is carried out in the temperature range of 400 ℃ ~ 600 ℃ under vacuum of 10 ^-5 -10 ^-6 Torr. Dispersion coating is carried out without a resin, or for the purpose of improving the adhesiveness, using a coating liquid in which a titanium phthalocyanine compound is dispersed in an appropriate resin solution. The coating is performed by using a device such as a spin coater, an applicator, a dip coater and a spray coater.
Drying is preferably performed by heating and drying at 40 to 200 ° C. for 10 minutes to 6 hours under static or blown conditions. The film thickness after drying is
It is coated to a thickness of 0.01 to 5 microns, preferably 0.1 to 1 micron.

The binder that can be used when the charge generation layer is formed by coating can be selected from a wide range of insulating resins.
Organic photoconductive polymers such as vinylcarbazole, polyvinylanthracene and polyvinylpyrene can also be used. Preferably, polyvinyl butyral, polyester, polycarbonate, polymethylmethacrylate, acrylic, silicone, urethane, epoxy, phenoxy,
Resins such as vinyl chloride and vinyl chloride-vinyl acetate copolymer are used, but any insulating resin may be used. The resin contained in the charge generation layer is suitable to be 100% by weight or less, preferably 40% by weight or less with respect to the charge generation agent. Also, these resins may be used alone or in combination of two or more, and if necessary, a crosslinking resin such as isocyanate or melamine resin may be added for the purpose of crosslinking the thermosetting resin. Is.

The solvent used depends on the type of resin and is selected so that it does not adversely affect the charge transfer layer and the undercoat layer described later. Specifically, benzene, xylene, ligroin,
Aromatic hydrocarbons such as monochlorobenzene and dichlorobenzene, ketones such as acetone, methyl ethyl ketone and cyclohexanone, alcohols such as methanol, ethanol and isopropanol, esters such as ethyl acetate and methyl cellosolve, carbon tetrachloride, chloroform, Aliphatic halogenated hydrocarbons such as dichloromethane, dichloroethane and trichlorethylene, ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ether, N, N-dimethylformamide,
Amides such as N, N-dimethylacetamide, and sulfoxides such as dimethyl sulfoxide are used.

The charge transfer layer is formed by coating the charge transfer agent alone or with an adhesive resin by dissolving and dispersing it in an appropriate solvent. As the charge transfer agent, the compound represented by the general formula [II] is used. The resin used for the charge transfer layer is selected from those listed as the resins used for the charge generation layer. The coating is performed using a spin coater, applicator, dip coater, spray coater, etc., and the film thickness after drying is 5
To 50 μm, preferably 10 to 20 μm.

The mixing ratio of the resin and the compound of general formula [II] is 100
The amount of the compound of the general formula [II] is preferably 10 to 500 parts by weight per part by weight. These resins may be used alone or in combination of two or more.

Further, the solvent used in forming the charge transfer layer of the present invention includes many useful organic solvents. For example, aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, and naphthalene, ketones such as acetone 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, ethylene chloride, and chloroform, tetrahydrofuran, 1, 4-dioxane, cyclic ether such as ethyl ether,
Alternatively, linear ethers or the like, or a mixed solvent thereof may be mentioned.

In addition to each of these layers, an undercoat layer may be provided on the conductive substrate for the purpose of improving charging stability and adhesiveness. As the undercoat layer, nylon, copolymer nylon, polyamide resin such as alkoxymethylated nylon, casein,
There are resins such as polyvinyl alcohol, gelatin, polyvinyl butyral and the like, inorganic compounds such as aluminum oxide, and conductive substrates themselves which are provided with an insulating property by oxidation treatment or the like. Further, the conductivity of the undercoat layer can be adjusted by incorporating conductive and dielectric particles such as metal oxides such as zinc oxide and titanium oxide, carbon black, silicon carbide and silicon nitride into fat. The film thickness is 0.01 to 50 μm, preferably 0.1 to 1 μm.

The support used for the electrophotographic photosensitive member of the present invention may be any one as long as it has conductivity, and may be any conventionally used conductive layer. Specifically, aluminum, copper, stainless steel, iron,
Metals such as brass, tin, and nickel, and those made of metal, such as paper, plastic, and polyethylene terephthalate (PET) polymer films that have been vapor-deposited or laminated to make them electrically conductive. Is also good. Further, the shape thereof may be a sheet shape, a cylinder shape, or any other shape.

LEDs have also been put into practical use as digital light sources for printers.

LEDs in the visible light range are also used, but those that have been put into practical use have an oscillation wavelength of 650 nm or more, typically 660 nm. Since the electrophotographic photoconductor has a spectral sensitivity peak around 650 nm, it is also effective as an LED material.

Hereinafter, examples of the present invention will be specifically described. In the examples, “part” means “part by weight”.

Examples 1 to 21 A sheet in which 10 parts of copolymerized nylon (Amylan CM-8000 manufactured by Toray Industries Inc.) was mixed with 190 parts of ethanol in a ball mill for 3 hours, and the coating solution was dissolved to deposit aluminum on a polyethylene terephthalate (PET) film After coating with a wire bar on top, dry at 100 ° C for 1 hour to obtain a film thickness of 0.5.
A sheet with a micron subbing layer was obtained.

Next, the exemplified compounds of titanium phthalocyanine compounds shown in Table 1 were used as the charge generating agent.

The X-ray diffraction patterns (a) to (g) of the titanium phthalocyanine compound shown in Table 1 are shown in FIG. 1, and the crystal pattern is not based on the chemical formula.

2 parts of the titanium phthalocyanine compounds of Examples 1 to 21 were dispersed in a ball mill for 2 hours together with a resin solution prepared by dissolving 1 part of vinyl chloride-vinyl acetate copolymer resin (VMCH manufactured by Union Carbide Co.) in 97 parts of dioxane.

This dispersion is applied on the undercoat layer and dried at 100 ° C. for 1 hour to form a 0.2 μm charge generation layer. Next, as a charge transfer agent, an exemplified compound (II-a) of the compound of the general formula [II]
1 part of a polycarbonate resin (Panlite L-1250 manufactured by Teijin Chemicals Ltd.) was mixed and dissolved in 8 parts of methylene chloride. This solution was applied on the charge generation layer and dried at 50 ° C. for 1 hour, and then a 15 μ charge transfer layer was formed to obtain an electrophotographic photoreceptor.

[II-a]

The electrophotographic characteristics of the photoconductor were measured by the following methods.

Electrostatic copying paper tester SP-428 (manufactured by Kawaguchi Denki Co., Ltd.) static mode 2, corona charging is -5.2KV, surface potential and 5lux white light is applied, and the charging amount is 1/2 and 1/5.
The half-white light exposure sensitivity (E1 / 2 and E1 / 5) was examined from the time it decreased to. Also, the evaluation of the repeatability is -5.
Charging under the conditions of 2KV and corona linear velocity of 120mm / sec, left in the dark for 2 seconds, and exposed for 3 seconds at 5lux, repeated in this order. Initial surface potential (V ₀ ), potential after leaving for 2 seconds in the dark (V ₂ ), And changes in residual potential (VR ₃ ) and sensitivity (E1 / 2, E1 / 5) after exposure for 3 seconds at 5 lux were measured.

As for the photo memory property (PM), after the photoreceptor is left under 600 lux white light for 3 minutes, it is left in the dark for 1 minute, and electrostatic characteristics are measured again under the same conditions. Therefore, the change in the charging potential of the photoconductor before irradiation with 600 lux and the change in the charging potential after irradiation were used as photo memory (PM). Therefore, the photo memory (P
M) is shown by the following equation.

PM = surface potential before exposure to high illuminance (600lux) -surface potential after exposure to high illuminance From the results shown in Table 2, the electrophotographic photoreceptors obtained in this example have excellent sensitivity, low residual potential, and very good results which are almost the same as the initial characteristics even after 10,000 repeated tests. was gotten. In addition, the photo memory (PM) is also small, and it can be seen that the photoconductor is stable against irradiation light.

Examples 22 to 28 Using the exemplified compounds of the titanium phthalocyanine compounds shown in Table 3, charge generation layers were formed by vapor deposition. 450 parts of titanium phthalocyanine-based compound under vacuum conditions of 10 ^-5 Torr
It was heated to sublimate at ℃ and precipitated on the cooled substrate to obtain 9.5 parts of crystals. On a PET film having an undercoat layer formed under the same conditions as in Examples 1 to 21, a vacuum condition of 10 ^-5 Torr was applied, and 550
A charge generation layer having a curtain thickness of 0.15 μm at 0 ° C. was obtained. Then, a charge transfer layer was formed under the same conditions as in Examples 1 to 21, and the electrophotographic characteristics were measured.

From the results shown in Table 4, even in the electrophotographic photosensitive member having the charge generation layer obtained by the vapor deposition method, extremely good results were obtained by combining with the charge transfer agent represented by the general formula [II]. Also, the photo memory (PM) is small,
It can be seen that the photoconductor is stable against irradiation light.

Comparative Examples 1 to 4 In place of the exemplified compound (II-a) used in Examples 1 to 28, the charge transfer agent shown in Table 5 was used, except for the conditions shown in Table 5, Example 1 A photoconductor was prepared under the same conditions as ~ 28 and the electrophotographic characteristics were compared. The results are shown in Table 6.

Comparing the results of Comparative Examples 1 to 4 with the examples, the residual potential is high, the sensitivity is inferior, and the stability in repetition is insufficient. In addition, the photo memory is also large and the surface potential is greatly reduced by light irradiation.

The photo memory is a phenomenon in which when the electrophotographic photosensitive member is irradiated with strong light, the holding potential of the surface of the photosensitive member, which is generated in the subsequent charging and exposure processes, largely changes compared to before the light irradiation. Depending on the intensity of the light, it may be temporary or may not be permanently restored. Therefore, if the photomemory property is small, the charging property is stable even when exposed to irradiation light or natural light when the photoconductor is handled. Therefore, when actually used in a copying machine or a printer, the electrophotographic characteristics are extremely stable. Is obtained. As a result, there is an advantage that a good image which is stable in terms of image can be obtained.

The electrophotographic photosensitive member of the present invention has high sensitivity, is stable during repeated use, has a good photomemory property, and can obtain a stable and high-quality image.

(Effects of the Invention) According to the present invention, an electrophotographic photosensitive member having high sensitivity and stable during repeated use, having a good photomemory property, and providing a stable and high-quality image was obtained.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction diagram of the titanium phthalocyanine compounds used in Examples 1-28 and Comparative Examples 1-4.

Claims (4)

[Claims] 1. An electrophotographic photoreceptor comprising a charge generating agent and a charge transfer agent on a conductive support, wherein the charge generating agent is a titanium phthalocyanine compound represented by the general formula [I]. An electrophotographic photoreceptor, wherein the agent is a compound represented by the general formula [II]. (In the formula, R ₁ represents a halogen atom, an oxygen atom or an alkoxy group, R ₂ , R ₃ , R ₄ and R ₅ represent a hydrogen atom, a halogen atom,
Represents a substituent such as an alkyl group, an alkoxy group, an aryl group, an aryloxy group, a nitro group, a cyano group, a hydroxyl group, a benzyloxy group, and an amino group, and j is an integer of 1 or 2,
k, l, m and n represent an integer of 0-4. ) (In the formula, R ₆ and R ₇ are a hydrogen atom, an alkyl group, an alkoxy group and an aryl group, and R ₈ , R ₉ and R ₁₀ are a hydrogen atom or -NR
₆ (R ₇ ) group is shown, and n is 0 or 1. ) 2. A non-crystalline titanium phthalocyanine compound having a primary particle diameter of 0.2 μm or less, which does not show a strong peak in an X-ray diffraction pattern, and is used. The electrophotographic photosensitive member described. ) 3. The Bragg angle (2θ ± 2 in the X-ray diffraction pattern.
The electrophotographic photosensitive material according to claim 1, wherein at least one of titanium phthalocyanine-based compounds showing a strong peak at the following positions (a) to (f) of 0.2 °) is used. body. (A) 7.5 °, 22.4 °, 24.4 °, 25.4 °, 26.2 °, 27.2 ° and 28.6 ° (b) 7.5 °, 22.4 °, 24.4 °, 25.4 °, 27.2 ° and 28.6
° (c) 7.5 °, 22.4 °, 24.4 °, 25.4 °, 26.2 ° and 28.6
° (d) 7.5 °, 22.4 °, 24.4 °, 25.4 ° and 28.6 ° (e) 6.9 °, 15.5 ° and 23.4 ° (f) 13.1 °, 20.6 °, 26.2 °, 26.5 ° and 27.0 ° 4. The electrophotographic photosensitive member according to claim 1, which has an inorganic or organic undercoat layer on a conductive support.