JPH06100837B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member that is preferably used in an image forming apparatus such as a copying machine.

(Prior Art) In recent years, as an electrophotographic photosensitive member having a photosensitive layer formed on a conductive substrate, an organic photosensitive member is used which has good processability and is advantageous in terms of manufacturing cost and has a large degree of freedom in functional design. Has been done. The above-mentioned organic photoreceptor has a photosensitive layer in which a charge generating function and a charge transporting function are separated by a charge generating material that generates a charge by light irradiation and a charge transporting material that transports the generated charge, thereby improving the sensitivity. There is known a function-separated type electrophotographic photoreceptor for achieving the above-mentioned purpose. The photosensitive layer of the function-separated electrophotographic photoreceptor is a laminated photoreceptor in which a charge generation layer containing at least a charge generation material and a charge transport layer containing a charge transport material and a binder resin are laminated. In addition, various types of single-layer type photoreceptors in which a charge generating material and a charge transporting material are dispersed in a binder resin have been proposed.

Since the laminated photoreceptor has various functions separated by the charge generation layer and the charge transport layer, it has an advantage that it has high sensitivity and a wide selection range of photosensitive materials, unlike the single-layer photoreceptor.

By the way, since many charge transport materials are of positive charge transport type and have a durable surface, a charge generation layer is provided on a conductive substrate, and a charge transport layer is further provided on the charge generation layer. It is common to have a body structure. However, in such a negative charging laminated photoreceptor, ozone is generated in the atmosphere at the time of negative charging to cause deterioration of the photoreceptor and pollution of the copying environment, and at the time of development, a positive charging toner which is difficult to manufacture is required. There is a problem such as

On the other hand, the above-mentioned single-layer type photoreceptor can be positively charged, and a negatively chargeable toner can be used as a toner for developing an electrostatic latent image on the photoreceptor. This is advantageous because, in general, it is easy to obtain a toner that is negatively charged, so that the selection range of toner materials is wide and various toner materials can be used. However, since electrons and holes are moved in one layer, one of them becomes a trap and the residual potential tends to increase. In addition, there is a problem that the combination of the charge generating material and the charge transporting material greatly affects the electrophotographic characteristics such as charging characteristics, sensitivity and residual potential.

Therefore, in an attempt to increase the sensitivity of a single-layer type photoreceptor in view of the above problems, N, N′-dimethylperylene-3,4,9,10-tetracarboxydiimide, N, N ′ as a charge generation pigment is used.
-Di (3,5-dimethylphenyl) perylene-3,4,9,10-
An electrophotographic photoreceptor comprising a perylene pigment such as tetracarboxydiimide, a binder resin, and acenaphthylene as a sensitizer (JP-A-58-76840), the above perylene pigment, and a charge transport material. An electrophotographic photosensitive member has been proposed which comprises the polyvinylcarbazole-based resin described above and terphenyl as a sensitizer (JP-A-59-119356).

(Problems to be Solved by the Invention) However, in the above-mentioned photoreceptor, sufficient electrophotographic characteristics cannot be obtained yet, and since a perylene compound is used as a charge generating material, the perylene compound has a long wavelength. Due to the lack of spectral sensitivity on the side, there is a problem in that sufficient sensitivity cannot be obtained when combined with a halogen lamp having large red spectral energy.

(Object of the Invention) The present invention has been made in view of the above problems, and by finding a combination of materials sufficiently satisfying the properties required for an electrophotographic photoreceptor, the sensitivity is improved and the repetitive properties are also improved. It is an object to provide an excellent single-layer type electrophotographic photoreceptor.

(Means and Actions for Solving Problems) Therefore, in the present invention, the following general formula [I] is used as a charge generating material in the binder resin. (Wherein R ¹ , R ² , R ³ and R ⁴ represent an alkyl group) and a general formula [II] below as a charge transport material. And a diamine derivative represented by the following formula, and a photosensitive layer containing 1.25 to 3.75 parts by weight of X-type metal-free phthalocyanine with respect to 100 parts by weight of the above perylene compound, are formed on a conductive substrate, and an electrophotographic photoreceptor is formed. The above object was achieved by constructing.

As a result of earnest studies by the present inventors, the diamine derivative represented by the general formula [II] as a charge transport material has good compatibility with a binder resin and has a small electric field strength dependency on drift mobility. Found to have.
The positively chargeable single-layer type electrophotographic photoconductor obtained by incorporating the perylene compound represented by the general formula [I] as a charge generating material in the binder resin has a charging property, a sensitivity and a residual potential. It has excellent electrophotographic characteristics, and by adding X-type metal-free phthalocyanine as a spectral sensitizer in the range of 1.25 to 3.75 parts by weight with respect to 100 parts by weight of perylene-based compound, the spectral sensitivity region becomes longer wavelength side. It was found that the shift occurred and the sensitivity of the photoconductor became higher.

X-type metal-free phthalocyanine perylene compound 10
The addition of 1.25 parts by weight or less to 0 parts by weight does not produce the sensitizing effect on the long wavelength side. Further, if 3.75 parts by weight or more of X-type metal-free phthalocyanine is added to 100 parts by weight of the perylene-based compound, the spectral sensitivity on the long wavelength side becomes high on the contrary, and the reproducibility of the red original becomes poor.

(Preferred Embodiment of the Invention) The perylene-based compound as the charge generating material used in the present invention is represented by the above general formula [I], and R ¹ , R ² , R ³ and R in the formula
Examples of the alkyl group among ⁴ include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl and hexyl groups.

Specifically, N, N'-di (3,5-dimethylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-
Di (3-methyl-5-ethylphenyl) perylene-3,4,
9,10-Tetracarboxydiimide, N, N'-di (3,5-diethylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3,5-dipropylphenyl ) Perylene-3,4,9,10-tetracarboxydiimide, N, N '
-Di (3,5-diisopropylphenyl) perylene-3,4,
9,10-Tetracarboxydiimide, N, N'-di (3-methyl-5-isopropylphenyl) perylene-3,4,9,10
-Tetracarboxydiimide, N, N'-di (3,5-dibutylphenyl) perylene-3,4,9,10-tetracarboxydiimide, N, N'-di (3,5-di-tert-butylphenyl )
Perylene-3,4,9,10-tetracarboxydiimide, N,
N'-di (3,5-dipentylphenyl) perylene-3,4,9,
10-tetracarboxydiimide, N, N'-di (3,5-dihexylphenyl) perylene-3,4,9,10-tetracarboxydiimide and the like are exemplified, but among them, N, N'-di (3 ,Five
-Dimethylphenyl) perylene-3,4,9,10-tetracarboxydiimide is preferred.

Examples of the diamine derivative as the charge transport material used in the present invention include 3,3′-dimethyl-N, N, N ′, N′-tetrakis-4-methylphenyl (represented by the general formula [II]. 1,1'-biphenyl) -4,4'-diamine is used.

As the binder resin used in the present invention, various ones, for example, a styrene polymer, an acrylic polymer, a styrene-acrylic polymer, polyethylene, an ethylene-vinyl acetate copolymer, a chlorinated polyethylene, a polypropylene. ,
Olefin-based polymers such as ionomer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester,
Alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, and photocurable resin such as epoxy acrylate. Polymers can be used, but the sensitivity of the photoconductor is improved, the abrasion resistance and repeatability of the photoconductor are excellent, and the selection range of the solvent that dissolves the binder resin is wide (4,4 ').
-Cyclohexylidenediphenyl) carbonate is preferred. When poly (4,4′-cyclohexylidenediphenyl) carbonate is used, tetrahydrofuran is different from bisphenol A type polycarbonate, which has conventionally been able to use only chlorine-based solvents such as dichloromethane and monochlorobenzene from the viewpoint of solution stability. Since a solvent such as methyl ethyl ketone can also be used, it is preferable in terms of safety and hygiene and is easy to handle. Among the above poly (4,4′-cyclohexylidenediphenyl) carbonates, the molecular weight is 15,000 to 25,000 and the glass transition point is 58 ° C.
Something is preferable.

The use ratio of the perylene compound, the diamine derivative and the binder resin is not particularly limited and can be appropriately selected according to the desired characteristics of the electrophotographic photoreceptor, etc., but the binder resin is 100 parts by weight. On the other hand, the perylene compound is 2 to 20 parts by weight, preferably 3 to 15 parts by weight, the diamine derivative 40 to
200 parts by weight, preferably 50-100 parts by weight are used. When the amount of the perylene compound and the diamine derivative used is less than the above-mentioned amount, not only the sensitivity of the photoconductor is insufficient but also the residual potential becomes large. On the other hand, if it exceeds the above range, the abrasion resistance of the photoconductor becomes insufficient.

Incidentally, when the above-mentioned perylene-based compound is used in a large amount, the positive charging property becomes insufficient, and when it is a small amount, the sensitivity and the like decrease, but in the electrophotographic photoreceptor of the present invention, the specific perylene-based compound and diamine are used. Since the derivative and the X-type metal-free phthalocyanine are combined, an electrophotographic photosensitive member having a high sensitivity and a high surface potential even when the amount of the perylene compound is small and having a small residual potential and excellent positive charging property is obtained. You can

The X-type metal-free phthalocyanine used in the present invention has Bragg angles (2θ ± 0.2 °) of 7.5 °, 9.1 °, 16.
Those showing strong diffraction peaks at 7 °, 17.3 ° and 22.3 ° are preferable. By adding 1.25 to 3.75 parts by weight of the X-type metal-free phthalocyanine to 100 parts by weight of the perylene-based compound, the spectral sensitivity region shifts to the longer wavelength side, and the sensitivity of the photoconductor becomes higher. However, the addition of 1.25 parts by weight or less of X-type metal-free phthalocyanine to 100 parts by weight of the perylene compound does not produce the sensitizing effect on the long wavelength side. Further, if 3.75 parts by weight or more of X-type metal-free phthalocyanine is added to 100 parts by weight of the perylene-based compound, the spectral sensitivity on the long wavelength side becomes high on the contrary, and the reproducibility of the red original becomes poor.

In addition, when an antioxidant is used in combination, it is possible to preferably prevent deterioration of a charge transporting material or the like having a structure that is affected by oxidation and is inexpensive, due to oxidation.

As the above-mentioned antioxidant, 2,6-di-tert-butyl-p
-Cresol, triethylene glycol-bis [3-
(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], penta Erythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-] Hydroxyphenyl) propionate], 2,2-thiobis (4-
Methyl-6-tert-butylphenol), N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,
Examples thereof include phenolic antioxidants such as 4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, and among them, 2,6-di-tert-butyl-p -Cresol is preferred.

The photoconductor of the present invention can be obtained by preparing a coating solution containing each of the above-mentioned components, coating the coating solution on a conductive substrate, and drying.

The conductive substrate may be in the form of a sheet or a drum having conductivity, various materials having conductivity,
For example, aluminum whose surface is anodized or untreated, aluminum alloy, copper, tin, platinum, gold,
A simple metal such as silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, or brass, or a plastic material on which a layer of the above metal, indium oxide, tin oxide or the like is formed by a method such as vapor deposition. Examples thereof include glass and the like, but among them, aluminum subjected to anodic oxidation by the sulfuric acid alumite method and sealed with nickel acetate is preferable.

In addition, the conductive substrate may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanium coupling agent, if necessary, to enhance the adhesion to the photosensitive layer.

In adjusting the coating solution, an appropriate organic solvent is used according to the type of the binder resin used, and the organic solvent includes, for example, alcohols such as methanol, ethanol, propanol, isopropanol, butanol, Aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, tetrahydrofuran, ethylene glycol dimethyl ether,
Ethers such as ethylene glycol diethyl ether,
Various solvents such as acetone, methyl ethyl ketone, cyclohexanone, and other ketones, ethyl acetate, methyl acetate, and other esters are exemplified, and one solvent or a mixture of two or more solvents is used. Further, when adjusting each of the above-mentioned coating solutions, in order to improve dispersibility, coatability, etc., silicone oil such as polydimethylsiloxane, a leveling agent such as a surfactant, or terphenyl, halonaphthoquinones, acenaphthylene, etc. Various additives such as conventionally known sensitizers may be used in combination.

Each of the above-mentioned coating liquids and the like can be prepared by using a conventionally used mixing / dispersing method, for example, a paint shaker, a mixer, a ball mill, a sand mill, an attritor, an ultrasonic disperser, or the like, and the obtained dispersion liquid or the like is coated. On the occasion,
Conventional coating methods such as dip coating, spray coating, spin coating,
Roller coating, blade coating, curtain coating, bar coating and the like are used.

The single-layer type photosensitive layer of the electrophotographic photosensitive member of the present invention may have an appropriate thickness, but is 15 to 30 μm, and particularly 18 to 27 μm.
Those having a thickness of are preferable.

(Example) Hereinafter, the present invention will be described in more detail based on Examples.

Example 1 100 parts by weight of poly- (4,4′-cyclohexylidenediphenyl) carbonate (trade name Polycarbonate Z, manufactured by Mitsubishi Gas Chemical Co., Inc.), N, N′-di (3,5-dimethylphenyl)
Perylene-3,4,9,10-tetracarboxydiimide 8 parts by weight, X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals, Inc.) 0.2 parts by weight, 3,3'-dimethyl-N, N, N ', N'- Tetrakis-4-methylphenyl (1,1'-biphenyl)-
4,4'-diamine 100 parts by weight, polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.01 parts by weight and a predetermined amount of tetrahydrofuran are mixed and dispersed by an ultrasonic disperser to prepare a dispersion liquid for a single-layer type photosensitive layer, An electrophotographic photosensitive member was prepared by applying the composition onto an alumite-treated aluminum base tube, forming a photosensitive layer having a thickness of about 23 μm, and subjecting it to heat treatment at about 100 ° C.

Example 2 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 0.1 part by weight of X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals) in Example 1 was used.

Example 3 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 0.3 part by weight of X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals) in Example 1 was used.

Comparative Example 1 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 0.05 part by weight of X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals) in Example 1 was used.

Comparative Example 2 A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 0.4 part by weight of X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals) in Example 1 was used.

Comparative Example 3 Instead of the X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals) of Example 1, β-type metal-free phthalocyanine was used.
A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 0.2 part by weight was used.

Comparative Example 4 β-type metal-free phthalocyanine was used in place of the X-type metal-free phthalocyanine (manufactured by Dainippon Ink and Chemicals) of Example 1.
A single-layer type electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 0.6 part by weight was used.

Then, in order to examine the charging characteristics and the photosensitive characteristics of the electrophotographic photoreceptors obtained in the above-mentioned Examples and Comparative Examples, an electrostatic copying test apparatus (Gentec Cynthia 30 manufactured by Gentec Co., Ltd.) was used.
M) was used to positively charge each of the electrophotographic photoconductors.

The surface potential V _SP (V) of each electrophotographic photosensitive member was measured, and the surface potential V _SP (V) was exposed to the surface of the electrophotographic photosensitive member using a tungsten lamp having an illuminance of 10 lux.
_Calculate the time until _SP becomes 1/2, and reduce the half exposure E1 / 2
(ΜJ / cm ² ) was calculated. The surface potential 0.15 seconds after the exposure was taken as the residual potential V _rp (V).

In addition, after copying a gray original with the same brightness as red and measuring the reflection density of the obtained copy with a reflection densitometer, The red reproducibility was examined by calculating The red reproducibility of 70% or less was evaluated as x, the range of 70 to 100% was evaluated as Δ, and the 100% or more was evaluated as o.

Table 1 shows the results of the charging characteristics, the photosensitive characteristics, etc. of the electrophotographic photosensitive members obtained in the above Examples and Comparative Examples.

As is clear from Table 1, the electrophotographic photosensitive members of Examples 1 to 3 all have excellent charging characteristics and high sensitivity.
It was found that the residual potential was small and the red color reproducibility was good.

On the other hand, the electrophotographic photosensitive members of Comparative Examples 1 and 2 were excellent in red reproducibility, but were low in sensitivity and high in residual potential. On the contrary, the electrophotographic photoreceptors of Comparative Examples 2 and 4 had poor red reproducibility.

(Effects of the Invention) As described above, according to the electrophotographic photosensitive member of the present invention, the positive charging property is excellent, and the sensitivity and the surface potential are high and the residual potential is small even though it is a single-layer type photosensitive member. Further, it has a peculiar effect that red reproducibility is also good.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keisuke Sumita 1-2-2 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Prefecture Mita Kogyo Co., Ltd. No. 28 Mita Kogyo Co., Ltd. Examiner Mitsuo Suma (56) References JP-A-62-103650 (JP, A) JP-A-63-188152 (JP, A) JP-B-5-20742 (JP, B2)

Claims (3)

[Claims] 1. A charge generating material in a binder resin, represented by the following general formula [I]: (Wherein R ¹ , R ² , R ³ and R ⁴ represent an alkyl group) and a general formula [II] below as a charge transport material. And a diamine derivative represented by the following formula, and a photosensitive layer containing 1.25 to 3.75 parts by weight of X-type metal-free phthalocyanine per 100 parts by weight of the above-mentioned perylene-based compound are formed on a conductive substrate. Photoreceptor. 2. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains an antioxidant. 3. A perylene-based compound is N, N'-bis (3,5-
The electrophotographic photosensitive member according to claim 1, which is dimethylphenyl) perylene-3,4,9,10-tetracarboxydiimide.