JP2000098641A - Coating fluid for electric charge generating layer and electrophotographic photoreceptor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating fluid for an electric charge generating layer having good dispersion stability, suitability to coating and electrophotographic characteristics and to obtain an electrophotographic photoreceptor using the coating fluid and having excellent in electrophotographic characteristics such as electrification ability, dark attenuation and sensitivity. SOLUTION: The coating fluid contains (A) a phthalocyanine compound, (B) a binder resin having repeating structural units of formula I and (C) 1-5 times (by weight) as much melamine resin or benzoguanamine resin as the binder resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for a charge generation layer of a function-separated type electrophotographic photosensitive member mounted on an electrophotographic apparatus (printer, copying machine, etc.) by the Carlson method, and an electrophotographic photosensitive member using the same It is about the body.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic photosensitive member using a photoconductive substance as a photosensitive material, selenium, zinc oxide,
Inorganic photoconductive materials such as titanium oxide and cadmium oxide have been mainly used. However, these are generally highly toxic, and there is also a problem in the disposal method.

On the other hand, when an organic photoconductive compound is used,
Recently, it has been widely studied because it is generally less toxic compared to the case of using inorganic photoconductive materials, and is advantageous in terms of transparency, flexibility, light weight, surface smoothness, and price. Is coming. When these photoconductors are applied to an electrophotographic apparatus based on the Carlson method, first, an electrostatic image is formed on the surface of the photoconductor, and then a developer generally called a toner charged to the same sign or a different sign is used. After development, the toner image is transferred and fixed to another substrate, for example, paper, and an image can be obtained.

In recent years, among photoreceptors using an organic photoconductive compound, many photoreceptors having a sensitivity in a semiconductor laser oscillation region of about 800 nm have been reported, and many of these photoreceptors are phthalocyanine pigments as charge generating substances. And a photosensitive layer is formed using a coating liquid in which a pigment is dispersed in a binder resin.

Phthalocyanines, which are pigments, not only have different absorption spectra and photoconductivity depending on the type of central metal, but also have different physical properties depending on the crystal type.
Some examples have been reported in which a specific crystal type is selected for an electrophotographic photoreceptor even with the same central metal phthalocyanine.

[0006] For example, it is reported that titanyl phthalocyanine has various crystal forms, and there is a great difference in chargeability, dark decay, sensitivity, etc. depending on the crystal form.

JP-A-59-49544 discloses that the crystal form of titanyl phthalocyanine is a Bragg angle (2
θ ± 0.2 degrees) are 9.2 degrees, 13.1 degrees, 20.7 degrees,
Those which give strong diffraction peaks at 26.2 degrees and 27.1 degrees are described as being suitable, and their X-ray diffraction spectra are shown.

Japanese Unexamined Patent Publication (Kokai) No. 59-166959 discloses a charge generation layer in which a deposited film of titanyl phthalocyanine is left in saturated vapor of tetrahydrofuran for 1 to 24 hours to change its crystal form to form a charge generation layer. I have. The X-ray diffraction spectrum has a small number of peaks and a wide peak, and has a Bragg angle (2θ) of 7.5 degrees, 12.6 degrees, 13.0 degrees,
It is shown to give strong diffraction peaks at 25.4, 26.2 and 28.6 degrees.

Japanese Patent Application Laid-Open No. Sho 64-17066 discloses a crystal form of titanyl phthalocyanine having a Bragg angle (2
θ ± 0.2 degrees) at least 9.5 degrees,
9.7 degrees, 11.7 degrees, 15.0 degrees, 23.5 degrees, 2
Those having 4.1 degrees and 27.3 degrees are described as being suitable.

[0010] JP-A-2-131243 and JP-A-2-214867 disclose that the crystal form of titanyl phthalocyanine has a Bragg angle (2θ ± 0.2 degrees) of 2;
It is described that those having a main diffraction peak at 7.3 degrees are preferable.

As described above, it is known that titanyl phthalocyanine has extremely high sensitivity and excellent characteristics due to the conversion of crystal form. However, in the application such as a laser printer, high image quality and high definition are progressing, and an electrophotographic photoreceptor having higher sensitivity characteristics is required.

As the binder resin, polyester resin, polyvinyl chloride, silicone resin, polystyrene resin, polyvinyl butyral resin, phenoxy resin and the like are used.

JP-A-2-183263 discloses a method using titanyl phthalocyanine using a polyester resin as a binder resin and 1,2-dichloroethane as a dispersion solvent.

Japanese Unexamined Patent Publication (Kokai) No. 3-231753 discloses an X-type metal-free phthalocyanine using a modified polyvinyl chloride resin as a binder resin and tetrahydrofuran as a dispersion solvent.

JP-A-3-10257 discloses a method using titanyl phthalocyanine using a polyhydroxystyrene resin as a binder resin and ethanol as a dispersion solvent.

JP-A-3-33863 discloses that titanyl phthalocyanine uses an acrylic resin as a binder resin and cyclohexanone as a dispersion solvent,
With respect to titanyl phthalocyanine, a resin using a phenol resin as a binder resin and methyl isobutyl ketone as a dispersion solvent is shown.

Japanese Patent Application Laid-Open No. 4-81861 discloses a method using titanyl phthalocyanine using a polyvinyl butyral resin as a binder resin and 1,2-dimethoxyethane as a dispersion solvent.

However, in each case, the electrophotographic characteristics such as chargeability, dark decay, and sensitivity are not always satisfactory, and dispersion stability, coating properties, electrophotographic characteristics, environmental health In some cases, a halogen-based solvent having a problem in, for example, is required.

[0019]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and has excellent electrophotographic properties such as chargeability, dark decay and sensitivity, and dispersion stability, coating properties, electrophotographic properties and the like. An object of the present invention is to provide a good charge generation layer coating solution and an electrophotographic photoreceptor using the same.

[0020]

DISCLOSURE OF THE INVENTION The present invention relates to (A) a phthalocyanine compound, (B) a compound represented by the general formula (I):

[0021]

Embedded image A binder resin having a repeating structural unit represented by the formula: and (C) a charge generation layer coating liquid comprising a melamine resin or a benzoguanamine resin in an amount of 1 to 5 times (weight ratio) the binder resin, and The present invention relates to the electrophotographic photosensitive member used.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The coating solution for a charge generating layer of the present invention comprises (A) a phthalocyanine compound, (B) a binder resin having a repeating structural unit represented by the general formula (I), and (C) one of the binder resins. Charge generation of a function-separated electrophotographic photoreceptor containing at least two layers of a melamine resin or a benzoguanamine resin as an essential component, and a photoconductive layer including at least two layers of a charge generation layer and a charge transport layer. Used to form layers.

In the present invention, the phthalocyanine compound is not particularly limited, but preferred examples include copper phthalocyanine, aluminum chloride phthalocyanine, chloroindium phthalocyanine, titanyl phthalocyanine,
Phthalocyanine pigments such as metal phthalocyanine such as vanadyl phthalocyanine and non-metal phthalocyanine are exemplified.

Further, as the phthalocyanine compound, α
Pigments known to generate electric charges, such as metal-free phthalocyanine compounds having various crystal structures such as type, β type, γ type, δ type, ε type, and χ type.

These pigments are described, for example, in JP-A-47-3
JP-A-7543, JP-A-47-37544, JP-A-47-18543, JP-A-47-18544, JP-A-48-43942, JP-A-48-7
0538, JP-A-49-1231, JP-A-49-105536, JP-A-50-75214, JP-A-53-44028, JP-A-54-1
No. 7,732, and the like.

Further, τ-type metal-free phthalocyanine, τ'-type metal-free phthalocyanine, η-type metal-free phthalocyanine, and η'-type metal-free phthalocyanine disclosed in JP-A-58-182640 and EP-A-92255. Metal phthalocyanines can also be used. In addition to these, any organic pigment that generates charge carriers by light irradiation can be used.

Further, phthalocyanine compositions disclosed in JP-A-6-175382 and the like can also be used.

The phthalocyanine composition is not particularly limited as long as it is a phthalocyanine composition containing two or more phthalocyanine compounds, and known ones can be used.
It is preferable that the phthalocyanine composition contains titanyl phthalocyanine from the viewpoint of electrophotographic properties. Further, from the viewpoint of electrophotographic properties, it is preferable that the phthalocyanine composition is obtained by converting a phthalocyanine mixture containing titanyl phthalocyanine and a central metal containing a trivalent halogenated metal phthalocyanine into an amorphous state, and then treating the mixture with an organic solvent, More preferably, the trivalent metal is In (indium). Further, in the X-ray diffraction spectrum of CuKα, the phthalocyanine composition has a Bragg angle (2θ ± 0.2 degrees) of 7.5 degrees and 22 degrees.
It is preferable from the viewpoint of electrophotographic characteristics to have main diffraction peaks at 5 degrees, 24.3 degrees, 25.3 degrees and 28.6 degrees.

In general, a phthalocyanine mixture is a mere physical mixture of two or more phthalocyanines used as raw materials, and the X-ray diffraction pattern of the phthalocyanine mixture is the peak pattern of each phthalocyanine used alone as a raw material. It consists of superposition.

On the other hand, the phthalocyanine composition is a mixture of phthalocyanine used as a raw material at a molecular level, and the X-ray diffraction pattern is different from the superposition of the peak patterns of the individual phthalocyanines used as the raw material. It shows.

The above titanyl phthalocyanine can be obtained according to the description in JP-A-3-71144, and can be produced, for example, as follows. 18.4 g (0.144 mol) of phthalonitrile are added to 120 ml of α-chloronaphthalene, and then 4 ml (0.0364 mol) of titanium tetrachloride are added dropwise under a nitrogen atmosphere.
After dropping, the mixture was reacted at 200 to 220 ° C. for 3 hours while heating and stirring, and then filtered while hot at 100 to 130 ° C. to obtain α-
Wash with chloronaphthalene and then methanol. The washed product is hydrolyzed with 140 ml of deionized water (1 hour at 90 ° C.).
This operation is repeated until the solution becomes neutral, and then washed with methanol. Next, it is sufficiently washed with N-methylpyrrolidone heated to 100 ° C., and then washed with methanol. The compound obtained in this way is
It is possible to obtain titanyl phthalocyanine by drying by heating under vacuum at ℃ (46% yield).

In the above-mentioned metal halide phthalocyanine whose central metal is a trivalent metal, 3
Examples of the valent metal include In, Ga, and Al, and In is preferable. As the halogen, for example, C
l, Br and the like. Further, the phthalocyanine ring may have a substituent such as halogen. These compounds are known compounds. For example, a method for synthesizing a monohalogenated metal phthalocyanine and a monohalogenated metal phthalocyanine is described in Inorganic Chemistry, 1
9, 3131 (1980) and JP-A-59-4405.
No. 4, for example.

The monohalogenated metal phthalocyanine can be produced, for example, as follows. 78.2 mmol of phthalonitrile and 15.8 metal trihalides
100 mmol of quinoline, which was distilled twice and deoxygenated
After heating under reflux for 0.5 to 3 hours, the mixture was gradually cooled, then cooled to 0 ° C., filtered, and the obtained crystals were washed with methanol, toluene, and then acetone, and then washed with methanol.
Dry at 10 ° C.

The monohalogenated metal halogen phthalocyanine can be produced, for example, as follows. 156 mmol of phthalonitrile and 37.5 mmol of metal trihalide are mixed and melted at 300 ° C., and then heated for 0.5 to 3 hours to obtain a crude product of a metal monohalogen phthalocyanine. This crude product can be washed with α-chloronaphthalene using a Soxhlet extractor to obtain a monohalogenated metal halide phthalocyanine.

In the present invention, the composition ratio of the titanyl phthalocyanine and the phthalocyanine mixture containing a trivalent halogenated metal phthalocyanine as the central metal is determined based on the content of titanyl phthalocyanine from the viewpoint of electrophotographic characteristics such as chargeability, dark decay, and sensitivity. Is preferably in the range of 20 to 95% by weight, more preferably in the range of 50 to 90% by weight, particularly preferably in the range of 65 to 90% by weight, and in the range of 75 to 90% by weight. Most preferably.

The phthalocyanine mixture can be made amorphous by an acid pasting method or the like. For example, 1 g of a phthalocyanine mixture is mixed with 50 m of concentrated sulfuric acid.
The solution is then dropped into 1 liter of ion-exchanged water cooled with ice water and reprecipitated. After collecting the precipitate by filtration, the precipitate is washed with pure water and then washed with a mixture of methanol / pure water at a pH of 2-5 and a conductivity of 5-5.
After washing until it becomes 00 μS / cm, it is dried at 60 ° C. to obtain an amorphous powder. The X-ray diffraction spectrum of the amorphous powder thus obtained is a spectrum showing a wide amorphous state without a clear sharp peak. As a method of making the amorphous state,
In addition to the acid pasting method using concentrated sulfuric acid, there is also a dry milling method.

The powder of the phthalocyanine mixture in an amorphous state is converted into a crystal by treating it with an organic solvent, and the X-ray diffraction spectrum of CuKα shows a Bragg angle (2θ ± 0.2 degrees) of 7.5 degrees. , 2
A phthalocyanine composition having main diffraction peaks at 2.5 degrees, 24.3 degrees, 25.3 degrees and 28.6 degrees can be obtained.

As a method for converting the amorphous phthalocyanine mixture into a crystal with an organic solvent, for example, 1 g of the phthalocyanine mixture powder in the amorphous state obtained in the above method is placed in 10 ml of an organic solvent and stirred under heating (the above powder / organic solvent ( Weight ratio) is 1/1 to 1/1
00). The heating temperature is 50 ° C to 200 ° C, preferably 80 ° C to 150 ° C, and the heating time is 1 hour to 10 hours, preferably 1 hour to 8 hours. After completion of the heating and stirring, the mixture is filtered, washed with methanol, and dried by heating under vacuum at 60 ° C., whereby about 700 mg of crystals of the phthalocyanine composition suitable for the present invention can be obtained. Examples of the organic solvent used in this treatment include alcohols such as methanol, ethanol, isopropanol, and butanol; alicyclic hydrocarbons such as n-hexane, octane, and cyclohexane; and aromatic hydrocarbons such as benzene, toluene, and xylene. Ethers such as tetrahydrofuran, dioxane, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, acetate cellosolve, acetone, methyl ethyl ketone, cyclohexanone, ketones such as isophorone, esters such as methyl acetate and ethyl acetate, dimethyl sulfoxide, dimethyl Formamide, phenol, cresol,
Non-chlorinated organic solvents such as anisole, nitrobenzene, acetophenone, benzyl alcohol, pyridine, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, quinoline, picoline, dichloromethane,
Examples thereof include chlorine-based organic solvents such as dichloroethane, trichloroethane, tetrachloroethane, carbon tetrachloride, chloroform, chloromethyloxirane, chlorobenzene, and dichlorobenzene.

Of these, ketones and non-chlorinated organic solvents are preferred, and among them, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, pyridine, methyl ethyl ketone and diethyl ketone are preferred.

The phthalocyanine composition can be obtained by the same method as described above. In the X-ray diffraction spectrum of CuKα, (i) the Bragg angle (2θ ± 0.2 degrees)
A phthalocyanine composition having major diffraction peaks at 9.3 degrees, 13.1 degrees, 15.0 degrees and 26.2 degrees, (i
i) 17.9 degrees of Bragg angle (2θ ± 0.2 degrees), 2
A phthalocyanine composition having major diffraction peaks at 4.0 degrees, 26.2 degrees and 27.2 degrees; (iii) 7.5 degrees, 24.2 degrees and 27 degrees of Bragg angles (2θ ± 0.2 degrees) .
Phthalocyanine compositions having three major diffraction peaks also exhibit excellent electrophotographic properties and can be used as preferred charge generating materials.

The coating solution for a charge generating layer of the present invention may contain, in addition to the phthalocyanine compound as a charge generating substance, another organic pigment which generates another charge. Examples of such organic pigments include, for example, azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinone, indigoid, quinacridone, perylene,
Methine-based organic pigments are exemplified. The amount of these organic pigments is preferably 0 to 50 parts by weight based on 100 parts by weight of the charge generating substance comprising the phthalocyanine composition and other organic pigments.

(B) The binder resin represented by the general formula (I) is a known resin, and commercially available products include, for example,
Phenoxy resin: PKHH (manufactured by Phenoxy Associates) is available.

The molecular weight of the binder resin having a repeating structural unit represented by the general formula (I) may be 20,000 to 900,000 in terms of polystyrene equivalent weight average molecular weight Mw measured by gel permeation chromatography. It is more preferably 30,000 to 250,000. If the molecular weight is less than 20,000, the mechanical strength of the photoconductive layer tends to be inferior, and the photoconductive layer tends to be easily attacked by the coating solvent of the charge transport layer applied on the production of the function-separated electrophotographic photosensitive member. Yes, if it exceeds 250,000, the workability tends to deteriorate when forming the photoconductive layer.

The coating solution for a charge generating layer of the present invention contains (C) a melamine resin or a benzoguanamine resin as an essential component. Melamine resin or benzoguanamine resin,
It is generally known that an amino group bonded to a triazine ring is treated with formaldehyde to form methylol and then methylol is further modified with alcohol. If these are melamine resins, melan 289,
As a melan 245 (manufactured by Hitachi Chemical Co., Ltd.) or the like, if it is a benzoguanamine resin, melan 331 and melan 36
5 (manufactured by Hitachi Chemical Co., Ltd.) and the like. Melamine resin and benzoguanamine resin form a charge generation layer with excellent film forming properties, dispersibility, adhesion, and moisture resistance, and have sensitivity, photoresponsiveness, potential holding properties, residual potential,
This is effective in improving image characteristics. In particular, at least 50% of the amino groups bonded to the triazine ring are methylolated, and it is preferable that at least 50% of the methylols are modified. As the denatured alcohol, propyl alcohol, n-butanol and isobutanol are preferred. The melamine resin and the benzoguanamine resin preferably have a weight average molecular weight Mw of 500 to 10,000 in terms of polystyrene measured by gel permeation chromatography,
000 is more preferred.

(C) The amount of the melamine resin or benzoguanamine resin used is 1 to 5 times (weight ratio) the binder resin represented by the general formula (I). This usage is
The amount is preferably 1.01 to 5 times, more preferably 1.3 to 3 times, particularly preferably 1.5 to 2.5 times. If the amount used is less than one time, the water absorption rate increases, and when used as an electrophotograph, there is an adverse effect such as blurring of an image, reduction in potential holding ability and sensitivity. On the other hand, when the amount used exceeds 5 times, the water absorption increases, the film quality of the charge generation layer becomes hard and brittle, and the mechanical properties deteriorate.

In the charge generating layer coating liquid, the total amount of (B) the binder resin and (C) the melamine resin or the benzoguanamine resin is 5 to the total amount of (A) the phthalocyanine compound and the organic pigment (charge generating substance). It is preferably adjusted to an amount of from 500 to 500% by weight, more preferably from 10 to 200% by weight, even more preferably from 30 to 150% by weight.

The coating liquid for a charge generating layer of the present invention usually contains a solvent, and as the solvent, a non-halogen solvent is preferably used from the viewpoint of environmental protection. In order to obtain a uniform coating film, the solvent needs to be capable of dissolving a binder resin having a repeating structural unit represented by the general formula (I) and a melamine resin or a benzoguanamine resin. Such solvents include, for example, ethylene glycol monoethyl ether, tetrahydrofuran, methyl ethyl ketone,
Examples thereof include dioxane and cyclohexanone, and among them, ethylene glycol monoethyl ether is preferable from the viewpoints of dispersibility, dispersion stability (the phthalocyanine compound (A) does not easily precipitate), coatability, environmental hygiene and the like. The amount of the solvent may be a total amount of (A) a phthalocyanine compound and an organic pigment that generates electric charge used as required, (B) a binder resin, and (C) a melamine resin or a benzoguanamine resin.
900 to 19900 parts by weight, preferably 1500 to 9900 parts by weight, per 100 parts by weight.

The electrophotographic photoreceptor of the present invention has at least two layers of a charge generating layer and a charge transport layer formed on a conductive substrate using the coating solution for a charge generating layer of the present invention. For example, either the charge generation layer or the charge transport layer may be an upper layer, or the charge generation layer may be sandwiched between two charge transport layers.

For the formation of the charge transport layer, a coating liquid for a charge transport layer containing a charge transport material and a binder for the charge transport layer is usually used. It is preferably adjusted to be 500% by weight or less, and more preferably 30 to 500% by weight.
When the charge transport substance is a low molecular weight compound, the binder is preferably contained in an amount of 50% by weight or more, more preferably 50 to 500% by weight, based on the charge transport substance.

As the charge transport material, various known materials can be used. In polymer compounds, poly-
N-vinyl carbazole, halogenated poly-N-vinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine, polyvinyl pyrazoline, etc., and low molecular weight compounds include fluorenone and fluorene , 2,7-dinitro-9-fluorenone, 4H-indeno (1,2,6) thiophene-4
-One, 3,7-dinitro-dibenzothiophene-5
Oxide, 1-bromopyrene, 2-phenylpyrene,
Carbazole, N-ethylcarbazole, 3-phenylcarbazole, 3- (N-methyl-N-phenylhydrazone) methyl-9-ethylcarbazole, 2-phenylindole, 2-phenylnaphthalene, oxadiazole, 2,5-bis (4-diethylaminophenyl)-
1,3,4-oxadiazole, 1-phenyl-3-
(4-diethylaminostyryl) -5- (4-diethylaminostyryl) -5- (4-diethylaminophenyl) pyrazolin, 1-phenyl-3- (p-diethylaminophenyl) pyrazolin, p- (dimethylamino) stilbene, 2- (4-dipropylaminophenyl) -4
-(4-dimethylaminophenyl) -5- (2-chlorophenyl) -1,3-oxazole, 2- (4-dimethylaminophenyl) -4- (4-dimethylaminophenyl) -5- (2-fluorophenyl ) -1,3-Oxazole, 2- (4-diethylaminophenyl) -4-
(4-dimethylaminophenyl) -5- (2-fluorophenyl) -1,3-oxazole, 2- (4-dipropylaminophenyl) -4- (4-dimethylaminophenyl) -5- (2-fluoro Phenyl) -1,3-oxazole, imidazole, chrysene, tetraphene, acridene, triphenylamine, benzidine and their derivatives.

Examples of the binder for the charge transport layer that can be used in the charge transport layer include silicone resin, polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polyacryl resin, polystyrene resin, and styrene resin. Examples include butadiene copolymer, polymethyl methacrylate resin, polyvinyl chloride, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, polyacrylamide resin, polyvinyl carbazole, polyvinyl pyrazoline, and polyvinyl pyrene. Further, a thermosetting resin and a photocurable resin which are crosslinked by heat and / or light can also be used. In any case, there is no particular limitation as long as it is an insulating resin capable of forming a film in a normal state, or a resin which is cured by heat and / or light to form a film.

The coating liquid for the charge transport layer usually contains a solvent, for example, an aromatic solvent such as toluene, xylene and anisole, a ketone solvent such as cyclohexanone and methylcyclohexanone, and a halogen such as methylene chloride and carbon tetrachloride. And hydrocarbon solvents, ether solvents such as tetrahydrofuran, 1,3-dioxolan, and 1,4-dioxane.

If necessary, additives such as a plasticizer, a fluidity-imparting agent, and a pinhole inhibitor can be added to the coating solution for the charge generation layer and the coating solution for the charge transport layer. Examples of the plasticizer include halogenated paraffin, dimethyl naphthalene, dibutyl phthalate, and the like.
Modaflow (manufactured by Monsanto Chemical), Acronal 4F (manufactured by Basf) and the like, and examples of the pinhole inhibitor include benzoin and dimethylphthalate. These may be appropriately selected and used, and the amounts thereof may be appropriately determined. Usually, (A) a phthalocyanine composition and an organic pigment that generates an electric charge that is used as needed,
The total amount of the additives is preferably 0 to 10 parts by weight, more preferably 0 to 5 parts by weight, based on 100 parts by weight of the total amount of the binder resin (B) and the melamine resin or the benzoguanamine resin (C). .

The electrophotographic photoreceptor of the present invention can be formed, for example, on a conductive substrate such as a paper or plastic film subjected to conductive treatment, a plastic film laminated with a metal foil such as aluminum, a metal plate, etc. The coating liquid for application is dried to form an undercoat layer, and the coating liquid for a charge generation layer of the present invention is applied thereon and dried to form a charge generation layer, and then the coating liquid for a charge transport layer is applied thereon and dried. Then, by providing a charge transport layer. The undercoat layer prevents charge injection from the conductive support to the photosensitive layer during charging of the photosensitive layer, and also causes the photosensitive layer to be integrally adhered and held to the conductive support. Are provided to prevent reflection of light from the conductive support. For its formation, usually, polymethylene, polypropylene, acrylic resin, methacrylic resin, polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate, polyurethane, polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-acetic acid An undercoat layer coating solution containing a known resin such as a vinyl copolymer, polyvinyl alcohol, a water-soluble polyester, nitrocellulose, casein, and gelatin is used.

The thickness of the charge generation layer is preferably 0.00
It is 1 to 10 μm, particularly preferably 0.2 to 5 μm.
If the thickness is less than 0.001 μm, it is difficult to form the charge generation layer uniformly, and if it exceeds 10 μm, the electrophotographic characteristics tend to deteriorate. The thickness of the charge transport layer is preferably 5
To 50 μm, particularly preferably 8 to 25 μm. 5μ
If the thickness is less than m, the initial potential is low, and if it exceeds 50 μm, the sensitivity tends to decrease.

As a coating method, a spin coating method, a dipping method, a roll coating method, an applicator coating method, a wire bar coating method, or the like can be adopted. When the coating liquid for a charge generation layer in the present invention is applied by a spin coating method, (A) a phthalocyanine compound, (B) a binder resin represented by the general formula (I), (C) a melamine resin or a benzoguanamine resin, It is preferable that the coating liquid for the charge generation layer obtained by dissolving or dispersing uniformly in a solvent such as ethylene glycol monoethyl ether is spin-coated at a rotation speed of 200 to 4000 rpm, and is also immersed in addition to the spin coating method. It can be formed by applying using a coating method such as a coating method, a roll coating method, an applicator coating method, a wire bar coating method, and drying.

The electrophotographic photoreceptor of the present invention may have a protective layer on the surface from the viewpoint of abrasion resistance.

[0059]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples of the present invention and Comparative Examples thereof, but the present invention is not limited to these Examples.

The materials used in the following examples are listed below. (A) charge transport material

[0061]

Embedded image Benzidine derivative (DPND) Production Example 1 1 g of a phthalocyanine mixture composed of 0.75 g of titanyl phthalocyanine and 0.25 g of indium phthalocyanine was dissolved in 50 ml of sulfuric acid and stirred at room temperature for 30 minutes.
This is added to about 1 liter of ion-exchanged water cooled with ice water.
It was added dropwise in 0 minutes to precipitate. After further stirring for 1 hour under cooling,
Left overnight. After removing the supernatant by decantation, a precipitate was obtained by centrifugation. This precipitate was washed six times with ion-exchanged water. Wash water pH after washing 6 times
And the conductivity was measured. For the measurement of pH, a model pH51 manufactured by Yokogawa Electric Corporation was used. The conductivity was measured using Model SC-17A manufactured by Shibata Scientific Instruments. The pH of the washing water was 3.3, and the conductivity was 65.1 μS / cm. Thereafter, the substrate was washed with methanol three times, and dried by heating under vacuum at 60 ° C. for 4 hours. Next, 1 g of the dried product was placed in 10 ml of 1,3-dimethyl-2-imidazolidinone, heated and stirred (150 ° C., 1 hour), filtered, washed with methanol, and dried by vacuum heating at 60 ° C. for 4 hours. Crystals of the phthalocyanine composition according to the present invention were obtained. The X-ray diffraction spectrum of CuKα of this crystal is shown in FIG.

Example 1 10 g of the phthalocyanine composition produced in Production Example 1 as a phthalocyanine composition (A) as a charge generating substance, and a phenoxy resin PKHH (manufactured by Phenoxy Associates) as a binder resin (B) (GPC) 3.06 g of melamine resin or melamine resin as a melamine resin or benzoguanamine resin (C) (manufactured by Hitachi Chemical Co., Ltd., solid content of 5).
1.0% by weight, Mw: 4000, methylolation ratio 67%
(Alcohol modification rate: 88%) 13.61 g and 380 g of ethylene glycol monoethyl ether were blended,
Dispersed in a ball mill. The coating liquid for a charge generation layer thus obtained is applied on a conductive substrate (aluminum plate 100 mm × 100 mm × 0.1 mm) by a dipping method.
After drying at 20 ° C. for 1 hour, a charge generation layer having a thickness of 0.5 μm was formed.

Next, the above (a) the charge transport material DPND
15g, polycarbonate resin Iupilon S-3000
(Mitsubishi Gas Chemical Co., Ltd.) 15 g and methylene chloride 155 g
Is coated on the above-mentioned charge generation layer by a dipping method, and dried at 120 ° C. for 1 hour to form a 20 μm-thick charge transport layer. The body was made.

Example 2 In Example 1, the component (C) melamine resin melan 28 was used.
Melamine resin melan 245 (manufactured by Hitachi Chemical Co., Ltd., solid content: 50.0% by weight, Mw: 2000, methylol conversion rate: 75% (alcohol modification rate: 89%)) was used in place of 9, 2. Phenoxy resin PKHH
A charge generation layer coating liquid and an electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that 95 g and melamine resin melan 245 were changed to 12.1 g.

Example 3 In Example 1, the component (C) melamine resin melan 28
Instead of 9, benzoguanamine resin melan 365 (manufactured by Hitachi Chemical Co., Ltd., solid content: 50.0% by weight, Mw: 20)
00, methylolation rate 30% (alcohol modification rate: 70)
%)) And the amount of phenoxy resin PKH
3.95 g of H and 12.1 of melamine resin melan 365
A coating solution for a charge generating layer and an electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that g was used.

Example 4 In Example 1, the component (B) phenoxy resin PKHH
And 2 g of (C) component melamine resin melan 289.
A coating solution for a charge generating layer and an electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that the amount was 69 g.

Example 5 In Example 1, the component (B) phenoxy resin PKHH
4.5 g, 1 component melamine resin melan 289 (C)
A coating solution for a charge generation layer and an electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that the amount was 0.78 g.

Comparative Example 1 In Example 1, the component (B) phenoxy resin PKHH
Was prepared in the same manner as in Example 1 except that the component (C) was not added.

Comparative Example 2 In Example 1, the component (B) phenoxy resin PKHH
Was used in the same manner as in Example 1 except that an acrylic resin Armatex WP640 (manufactured by Mitsui Toatsu Chemicals) was used in place of the above, to prepare a coating solution for a charge generation layer and an electrophotographic photosensitive member.

Comparative Example 3 In Example 1, the component (C) melamine resin melan 28
Epoxy resin Epicoat 828 (manufactured by Yuka Shell Epoxy Co., Ltd.) was used instead of Epicoat 8
A coating solution for a charge generation layer and an electrophotographic photoreceptor were prepared in the same manner as in Example 1, except that 28 was changed to 6.94 g.

Comparative Example 4 In Example 1, the component (B) phenoxy resin PKHH
And 1 g of (C) component melamine resin melan 289.
A coating solution for a charge generation layer and an electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that the amount was 65 g.

Comparative Example 5 In Example 1, the component (B) phenoxy resin PKHH
And 5.8 of melamine resin melan 289 (C).
A coating solution for a charge generating layer and an electrophotographic photoreceptor were prepared in the same manner as in Example 1 except that the amount was 8 g.

The dispersion stability of the charge generation layer coating liquids obtained in the above Examples and Comparative Examples was evaluated by the following method.

The coating solution for the charge generating layer was prepared by applying an inner diameter of 15 mm and a length of 2
10 ml was put into a test tube with a stopcock of 0 cm, sealed with a stopcock, allowed to stand at 23 ° C. for 60 days, and the sedimentation property was determined to be 2.3% (see FIG. 2). The sedimentation property is b / a
(%). Here, a is the height of the entire coating solution in the test tube, and b is the height of the upper portion in the test tube.

The water absorption of the charge generation layer was evaluated by the following method.

The water absorption was measured by applying the charge generation layer coating liquid to a dry thickness of 8 μm.
m, and dried at 120 ° C. for 1 hour. This was placed in a desiccator containing silica gel for 23 hours.
At 72 ° C. for 72 hours, weigh W1 and then
₄ H ₂ PO ₄ Saturated aqueous solution container (RH 93%, 23
° C) for 72 hours, weigh W2 (W2-W
1) / (W1 × 100)%.

The electrophotographic characteristics and image quality of the obtained electrophotographic photosensitive member were evaluated by the following methods.

The electrophotographic properties of the obtained electrophotographic photosensitive member were measured by an electrophotographic property evaluation apparatus Cynthia 30 (Gentec). Charging was performed by corona discharge at −5 kV in the dark, and the initial charge V ₀ (−V) after 10 seconds was evaluated. Further, the corona voltage was adjusted so that the initial charging potential became 700 V, the dark decay DDR (%) after 5 seconds, and the light amount 20 m
W / m ² , sensitivity E _1/2 when exposed to light with a wavelength of 780 nm
(MJ / m ² ) and the residual potential Vr one second after the start of exposure
(−V) was determined.

Separately from the above, the obtained electrophotographic photosensitive member is attached to an aluminum drum, which is charged, exposed, developed,
It was attached to a laser beam printer (negative charging reversal phenomenon system) consisting of transfer and cleaning, and the image quality was evaluated (charge: -400 V, exposure: 780 nm, 20 mJ / m ² , erase: 560 nm). The criteria for image quality evaluation were as follows.

(Evaluation) A: High quality image without defects B: Fog was slightly observed B ': Fog was observed a lot C: Some black spots were observed C': Many black spots were observed D: Some white spots were observed. D ': Many white spots were observed. E: Image density was low. F: No image was obtained on the entire surface or no image was obtained at all (overall white). Show.

[0081]

[Table 1]

[0082]

The coating solution for a charge generation layer of the present invention is excellent in dispersion stability (such as hardly sedimentation), coating property, environmental hygiene and the like. It has excellent electrophotographic characteristics such as dark decay and sensitivity, and can be suitably applied to electrophotographic processes that require higher density and higher image quality than before.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction spectrum of CuKα of a phthalocyanine composition used in Examples of the present invention.

FIG. 2 is a schematic diagram showing a method for evaluating the dispersion stability of a coating solution for a charge generation layer used in an example of the present invention.

[Explanation of symbols]

 1 Stopcock 2 Test tube 3 Above part 4 Settling part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Kaneko 4-3-1, Higashicho, Hitachi City, Ibaraki Prefecture Inside the Yamazaki Plant of Hitachi Chemical Co., Ltd. No. 1 Hitachi Chemical Co., Ltd. Yamazaki Plant (72) Inventor Osamu Higashida 4-3-1 Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Plant F-term (reference) 2H068 AA13 AA14 AA19 BA39 BB26 BB36 BB37 EA14

Claims (8)

[Claims] (A) a phthalocyanine compound, (B) a general formula (I) And (C) a coating liquid for a charge generation layer, comprising (C) a melamine resin or a benzoguanamine resin in an amount of 1 to 5 times (by weight) the binder resin. 2. The coating liquid for a charge generation layer according to claim 1, wherein the phthalocyanine compound is a phthalocyanine composition comprising two or more phthalocyanines. 3. The coating liquid for a charge generation layer according to claim 2, wherein (A) the phthalocyanine composition contains titanyl phthalocyanine. 4. The phthalocyanine composition according to claim 3, wherein the (A) phthalocyanine composition is obtained by converting titanyl phthalocyanine and a metal halide phthalocyanine having a trivalent metal as a central metal into an amorphous state, and then treating with an organic solvent. Coating solution for charge generation layer. 5. The method according to claim 4, wherein the trivalent metal is indium.
The coating solution for a charge generation layer according to the above. 6. The method of claim 1, wherein (A) the phthalocyanine composition is CuKα.
In the X-ray diffraction spectrum, the Bragg angle (2θ ±
0.2 degrees) 7.5 degrees, 22.5 degrees, 24.3 degrees, 2
The coating liquid for a charge generation layer according to claim 5, which has a main diffraction peak at 5.3 degrees and 28.6 degrees. 7. The coating for a charge generation layer according to claim 1, further comprising a non-halogen solvent capable of dissolving the binder resin according to claim 1 and a melamine resin or a benzoguanamine resin. liquid. 8. An electrophotographic photosensitive member using the coating liquid for a charge generation layer according to claim 1, 2, 3, 4, 5, 6, or 7.