JPH073584B2 - Electrophotographic photoconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention has high sensitivity in the near-infrared region used in an electrophotographic apparatus, particularly a laser beam printer using a semiconductor laser as a recording light source and a laser plate making system. The present invention relates to a photoconductor for electrophotography.

[Conventional technology]

Although the recording light source varies depending on the spectral sensitivity of the photoconductor,
In a system that uses a gas laser such as an Ar laser or a He-Ne laser as a recording light source, the laser has a high output, so an image can be formed in a relatively short time, but on the other hand, a complicated optical system and maintenance technology are required. Therefore, it is difficult to reduce the size and cost of the device.

Therefore, as a recording light source that meets the demand for downsizing and cost reduction of a device, a device using a semiconductor laser is being researched.

In recent years, there have been significant advances in semiconductor lasers, but the ones that have been put into practical use are those whose oscillation wavelength is longer than 780 nm, and are mainly used as light sources for printers or plate-making systems at 780 nm to 850 nm. The one with the oscillation wavelength is used.

At present, the output of semiconductor lasers is weaker than that of other lasers, so 780 to 850 nm for photoconductors used in semiconductor laser printers, semiconductor laser plate making systems, etc.
It is desired that the sensitivity be sufficiently high (for example, a half-exposure amount of 10 erg / cm ² or less) in the region (1).

As described above, as the electrophotographic photoreceptor, those using an inorganic compound such as zinc oxide, a copper phthalocyanine compound, an oxadiazole compound, etc. as a photosensitive substance have been reported, but these have a long wavelength of 780 nm to 850 nm. The photosensitivity was insufficient in the range.

[Problems to be solved by the invention]

Therefore, a problem to be solved by the present invention is to provide an electrophotographic photosensitive member which exhibits high sensitivity in a long wavelength region and can be used in a recording apparatus using a semiconductor laser as a recording light source.

[Means for solving problems]

The present invention is characterized in that a photosensitive layer having (a) a perinone compound, (b) a phthalocyanine compound and (c) a hole transporting substance dispersed in a (d) binder resin is provided on a conductive support. The present invention provides a photoconductor for electrophotography.

In the present invention, as the (a) perinone compound, various conventionally known perinone compounds as electrophotographic materials can be used without particular limitation. The compound represented by

Examples of the (b) phthalocyanine compound used in the present invention include metal or metal-free phthalocyanine compounds and aromatic nucleus-substituted compounds thereof. Substituted with a halogen atom, a nitro group, an amino group, or an optionally substituted alkyl, aralkyl, or aryl group for at least a part of the four benzene nuclei of the metal phthalocyanine compound represented by Phthalocyanine compounds described above, and particularly preferable ones are titanyl phthalocyanine compounds.

As the hole-transporting substance (c) used in the present invention, conventionally known hole-transporting substances as electrophotographic materials can be used without particular limitation, but hydrazone compounds, pyrazoline compounds and the like have low potential holding ability and are not preferred. . The hole transporting material having a high potential holding ability and suitable for the present invention includes 2,5-bis (4-dimethylaminophenyl) -1,3,4-oxadiazole and 2,5-bis (4-diethylaminophenyl). ) −
1,3,4-oxadiazole, 2,5-bis (4-aminophenyl) -1,3,4-oxadiazole, 2- (4'-aminostyryl) -5-phenyl-1,3, Oxadiazole compounds such as 4-oxadiazole, 2- (4'-aminostyryl) -5- (4 "-methylphenyl) -1,3,4-oxadiazole, N-methylcarbazole, N-ethyl N- such as carbazole and N-propylcarbazole
Alkylcarbazole compounds, dimethylaminobenzoic acid, diethylaminobenzoic acid, dialkylaminobenzoic acid such as dipropylaminobenzoic acid and the like can be mentioned. 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole represented by

Further, in the present invention, as the binder resin (d), a conventionally known binder resin as an electrophotographic material can be used without particular limitation, and preferred examples include acrylic resins, polyester resins, polycarbonate resins, Polystyrene resin, phenol resin, epoxy resin, urethane resin,
Examples include phenoxy resin.

The electrophotographic photoreceptor of the present invention includes, for example, the above (a) to
The compound of (c) is added to a solution in which a binder resin is dissolved in an appropriate organic solvent, and dispersed nonuniformly by using ball milling, paint shaker, red devil, ultrasonic disperser, etc. It can be prepared by coating and drying on a conductive support. For coating, a roll coater, wire bar, doctor blade, etc. are usually used.

Suitable solvents include, for example, aromatic hydrocarbons such as benzene and toluene; ketones such as acetone and butanone; halogenated hydrocarbons such as methylene chloride and chloroform; ethers such as ethyl ether; tetrahydrofuran. , Cyclic ethers such as dioxane; esters such as ethyl acetate and methyl cellosobuacetate, and these can be used alone or in combination.

The thickness of the photosensitive layer is preferably from 3 to 50 μm, particularly preferably 3 μm.
~ 15μ.

The proportion of the (a) perinone compound and (b) phthalocyanine compound in the photosensitive layer is preferably 0.5 to 90% by weight, and particularly preferably 10 to 40% by weight, based on the (d) binder resin. The proportion of the hole-transporting substance (c) is preferably 0.1 to 90% by weight, and particularly preferably 1 to 80% by weight, based on the binder resin (d).

For the conductive support of the photoreceptor, for example, a metal plate of aluminum or the like, a metal foil, a plastic film deposited with a metal of aluminum or the like, or a paper subjected to a conductive treatment is used.

Further, between the conductive support and the photosensitive layer, if necessary, an adhesive layer or a barrier layer may be provided, and as a material for these layers, polyamide, nitrocellulose,
Examples include casein and polyvinyl alcohol.

A laser plate making system for producing a printing plate using an electrophotographic photosensitive member having high photosensitivity to laser light has been developed, and this system has already been operated in the United States. Since the photoreceptor of the present invention has high sensitivity to laser light, it can be adapted to the printing plate of this system. In order to use the photoconductor of the present invention as a printing plate, a metal plate having a grained surface, preferably an aluminum plate, is used as a conductive support, and an alkali-soluble resin is used as a binder resin. As an alkali-soluble resin,
For example, styrene-maleic acid copolymer; polymerizable monomer such as acrylic monomer, vinyl acetate monomer, styrene monomer, vinyl chloride monomer and carboxyl-containing polymerizable monomer such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid. And the like can be used. A toner image is formed on the photoconductor of the present invention produced by using such a material by using an electrophotographic apparatus having a laser as a recording light source, and after fixing the toner image, the plate surface is treated with caustic soda, When developed with an alkaline aqueous solution containing sodium silicate or the like as an alkaline agent, the non-image portion is dissolved and removed, and only the toner image remains without being removed. At the time of printing, the toner image remaining on the plate surface becomes the image area, and the exposed metal surface becomes the non-image area. The printing plate thus produced can be used as a lithographic printing plate using a fountain solution.

[Action]

The sensitizing mechanism of the electrophotographic photoreceptor of the present invention will be briefly described below.

Conventionally, the phthalocyanine compound that has been reported is a hole-transporting substance, and a photosensitive layer obtained by uniformly dispersing this phthalocyanine compound in a binder resin exhibits good sensitivity only when positively charged, but when negatively charged. Since the holes are injected and transported from the support electrode, the charge retention ability is poor. Especially in a laser scan plate making system, such a property is not preferable. Even when a phthalocyanine compound is dispersed in a hole transport medium composed of an ordinary charge carrier transporting substance, for example, a compound such as an oxadiazole compound, a hydrazone compound, a pyrazoline compound and a binder resin, it shows a considerably high residual potential when negatively charged. Will end up.

However, the phthalocyanine compound-hole transport medium system phthalocyanine compound-hole transport material-binder resin dispersion system In the photoreceptor of the present invention to which an appropriate amount of perinone compound is added, the negative charge retention is surprising. The improvement in performance and the increase in sensitivity were observed, and it became possible to realize a high-sensitivity photoconductor even with a single layer even when negatively charged.

On the other hand, in view of the fact that the perinone compound containing no phthalocyanine compound-hole transporting substance-binder resin dispersion type photosensitive material shows almost no sensitivity on the longer wavelength side than 780 nm, the photosensitive material of the present invention is the perinone compound. -Phthalocyanine compound-It is considered that electronic interaction occurs among the three members, hole transporting substance, and generation and transport of charge carriers by excitation of the phthalocyanine compound is possible even by irradiation with long-wavelength light, showing high sensitivity. To be

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

All "parts" in each example are "parts by weight" unless otherwise specified.

〔Example〕

Example 1 120 parts of perinone compound represented by formula (I), formula (II)
10 parts of titanyl phthalocyanine represented by formula (VII)
150 parts of an oxadiazole compound represented by the formula: 660 parts of a carboxylated vinyl acetate resin (“RESYN28-2930” manufactured by National Starch and Chemical Corp .: = 20000) which is an alkali-soluble resin as a binder resin, and methyl ethyl ketone-methylene chloride. A mixture consisting of 5500 parts of a mixed solvent is uniformly dispersed using a paint shaker. The resulting dispersion is applied onto a anodic oxidized aluminum plate using a wire bar and dried to give a photosensitive layer thickness of 3 μm.
Create a photoconductor. The charging characteristics and photosensitivity of the electrophotographic photoreceptor thus prepared were measured. "Paper analyzer SP-428" (manufactured by Kawaguchi Electric Co., Ltd.) was used as a measuring machine.

(−) Measure the surface potential V ₀ (v) of the photoconductor immediately after applying each voltage of 6 kV to the surface of the photoconductor, and the surface potential V ₁₀ (v) of the photoconductor 10 seconds after the voltage application was stopped. The charge holding ability of the photoreceptor was evaluated by the value of V ₁₀ / V ₀ .

The sensitivity of the photoconductor was measured by exposing the surface of the charged photoconductor using a tungsten lamp of a white light source. Exposure amount required to reduce the surface potential after exposure to half of the initial surface potential with exposure intensity of 5 Lux And the amount of exposure required to reduce the surface potential after exposure to 1/5 of the initial surface potential. Then, the surface potential V _R15 (v) was measured 15 seconds after the start of exposure, and the light dispersed into 830 nm (light intensity 10 mW / m ² )
Irradiate the same Was measured. The sensitivity of the photoreceptor was evaluated based on these physical quantities, and the results are summarized in Table 1.

Comparative Examples 1 to 3 With the blending composition shown in Table 2, a photoreceptor was prepared in the same manner as in Example 1 and the characteristics were measured. The results are summarized in Table 3.

As is clear from this result, any photoreceptor of perinone compound-oxadiazole compound-resin dispersion system, titanyl phthalocyanine compound-resin dispersion system, or titanyl phthalocyanine compound-oxadiazole compound-resin dispersion system was negatively charged. Although it does not show practical sensitivity at times, it was confirmed that the photoreceptor of the present invention has high sensitivity even in a long wavelength region.

Examples 2 to 5 Photoreceptors were prepared in the same manner as in Example 1 with the blending composition shown in Table 4, and the characteristics were measured. The results are summarized in Table 5.

Example 6 Instead of the white light used in Example 1, monochromatic light was extracted by a combination of an interference filter and a bandpass filter and irradiated to halve the exposure amount. Was measured and the results are shown in Table 6.

Example 7 In the photoreceptor of Example 1, vinyl acetate-vinyl alcohol (polymerization ratio was used instead of the carboxylated vinyl acetate resin).
8: 2) was used as an alkali-soluble resin to prepare 660 parts of a copolymer, and a photoreceptor was prepared in the same manner as in Example 1, and the characteristics were measured. The initial potential was V ₀ 300v, Met. Next, an electrostatic latent image was formed, and toner development was performed using "CBR-100", a liquid developer manufactured by Dainippon Ink and the toner image was fixed at 180 ° C for 5 seconds. Subsequently, the PS plate developer "DP-4" manufactured by Fuji Film Co., Ltd.
Was diluted with water at a ratio of 8: 1 and developed at 25 ° C. for 30 seconds to obtain a printing plate having a high contrast image.

Examples 8 to 12 Photoreceptors were prepared in the same manner as in Example 1 except that the titanyl phthalocyanine in Example 1 was replaced with another phthalocyanine compound, and the characteristics were measured. The results are summarized in Table 7.

Example 13 120 parts of perinone compound represented by formula (I), formula (V)
10 parts of magnesium phthalocyanine represented by and 150 parts of an oxadiazole compound represented by the formula (VII):
Polyester resin (Byron 20 manufactured by Toyobo Co., Ltd.)
0 ") and a resin solution consisting of 660 parts and 5500 parts of a solvent (80 wt% of toluene-10 wt% of methyl ethyl ketone-10 wt% of acetone), and this mixture is uniformly dispersed using a paint shaker. Using this dispersion, a photoconductor was prepared in the same manner as in Example 1, the characteristics were measured, and the results are summarized in Table 8.

Example 14 A photoreceptor was prepared in the same manner as in Example 13 except that 600 parts of a phenoxy resin (“PKHH” manufactured by UCC Co., Ltd.) was used as the binder resin instead of the polyester resin, and the characteristics were measured. The results are summarized in the table.

Example 15 A photoconductor was prepared in the same manner as in Example 13 except that 10 parts of copper phthalocyanine represented by the formula (IV) was used instead of magnesium phthalocyanine, and the characteristics were measured. The results are summarized in Table 8.

[Effects of the Invention] The electrophotographic photoreceptor of the present invention comprises (a) a perinone compound,
By incorporating (b) a phthalocyanine compound and (c) a hole-transporting substance in the photosensitive layer, the sensitivity to long-wavelength light having a wavelength of 780 to 850 nm was dramatically increased, and the negative charge retention ability was significantly improved. It is a thing.

Therefore, the photoconductor of the present invention can be used as a photoconductor of a recording apparatus having a semiconductor laser as a recording light source.

Claims (5)

[Claims] 1. A photosensitive layer comprising (a) a perinone compound, (b) a phthalocyanine compound, and (c) a hole-transporting substance dispersed in a binder resin (d) is provided on a conductive support. Characteristic electrophotographic photoconductor. 2. The (a) perinone compound has the formula: The photoconductor according to claim 1, which is a compound represented by: 3. The photoconductor according to claim 1, wherein the hole-transporting substance (c) is an oxadiazole compound. 4. The oxadiazole compound has the formula The photoconductor according to claim 3, which is a compound represented by 5. The photoconductor according to claim 1, wherein the conductive support is a grained and / or water-retaining metal plate, and the binder resin is an alkali-soluble resin.