JP2751302B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member comprising a substrate, an intermediate layer and a photosensitive layer, and more particularly to an electrophotographic photosensitive member having an improved intermediate layer.

2. Description of the Related Art Conventionally, a copying machine using an electrophotographic system is represented by a micro printer, a liquid crystal shutter system printer, an LED printer, a laser beam printer, and the like, and is used in an electrophotographic latent image forming system. The disadvantages of the electrophotographic photoreceptors used in these copiers are that the dark decay is large, the charging characteristics are poor, and the residual potential is high, etc., so that the development contrast tends to decrease, white spots, black spots, rough spots, It is known that an image defect called a pinhole is likely to occur.

As a countermeasure for solving such a problem, it has been attempted to provide a resin layer between 0.1 μm and several tens μm between the substrate and the photosensitive layer.

As the resin layer, for example, polyparaxylene, casein, polyvinyl alcohol, phenol resin, polyvinyl acetal resin, melamine resin, nitrocellulose,
Known are those formed of ethylene-acrylic acid copolymer, polyamide, polyvinyl pyridine, polyacrylic acid, polyester, polyvinyl pyrrolidone, polyvinyl methyl ether, polystyrene, phenoxy resin, polyurethane, gelatin, various rubber resins, and the like. .

Problems to be Solved by the Invention However, in the conventionally known resin layer, only a part of the defect of the photoreceptor can be improved, or the effect is reduced by half if environmental characteristics and the like are included, and technically extremely insufficient It was something. For example, when nylons are used, they are dissolved only in a special solvent such as formic acid, so that the coating operation is difficult, or the residual potential of the electrophotographic photoreceptor is high, the contrast potential is reduced, and furthermore, the substrate and It has disadvantages such as poor adhesion between photosensitive layers.

In addition, for example, Japanese Utility Model Application Laid-Open No. 58-95351 describes that N-alkoxymethylated nylon or N-alkylated nylon is used, but the chargeability is excellent, but the residual potential is high. Alternatively, it has a problem that it is susceptible to fluctuation due to long-term repeated use.

As described above, in the prior art, the effect of the undercoating layer for removing various defects of the electrophotographic photosensitive member is still insufficient, and the characteristics of the photosensitive member are unsatisfactory.

A first object of the present invention is to provide an electrophotographic photoreceptor having a small dark decay, excellent charging characteristics, a low development contrast, and a particularly low residual potential.

A second object of the present invention is to provide a white spot, a black spot, a gasp,
An object of the present invention is to provide an electrophotographic photosensitive member in which image quality defects such as pinholes are unlikely to occur.

A third object of the present invention is to provide an electrophotographic photoreceptor having electrophotographic characteristics excellent in durability with little environmental fluctuation.

Means and Action for Solving the Problems The present invention provides an electrophotographic photoreceptor comprising a substrate, an intermediate layer and a photosensitive layer, wherein the intermediate layer is made of a modified polyamide resin, and the modified polyamide resin has an amide bond of 40 to 40.
70 mol% is mainly composed of nylon 6 having a substituted amide bond represented by the following structural formula or copolymer nylon containing nylon 6 as a constituent.

(In the formula, R represents a methyl group, an ethyl group, a propyl group or a butyl group.) Hereinafter, the present invention will be described in detail.

In the electrophotographic photoreceptor of the present invention, the intermediate layer is provided on a substrate, and any substrate can be used as the substrate, as long as it is known in the art of electrophotographic photoreceptors.

 The intermediate layer is composed of the above-mentioned modified polyamide resin.

The modified polyamide resin used in the present invention includes 6 nylon or copolymerized nylon containing 6 nylon as a constituent, for example, TLCairns et al. (J. Am. Chem. Soc., 71, pp65).
1 (1949)), and can be produced by modification with a mercaptan by a general method as proposed. The reaction proceeds as shown in the following formula, and the amide bond of nylon is replaced by a polar group.

For example, a modified polyamide is obtained by reacting a formalin mercaptan solution with a formic acid solution of 6 nylon or a copolymerized nylon containing 6 nylon as a constituent, then pouring the mixture into a non-solvent such as a water / acetone mixture, and neutralizing with ammonia. Precipitates. Industrially, it can be produced by directly reacting formalin and mercaptan on the above 6 nylon or copolymer nylon at high temperature and high pressure using a phosphoric acid catalyst.

As the degree of substitution of the polyamide bond increases, the crystallinity, melting point and elastic modulus of the modified polyamide resin decrease, and the solubility and flexibility increase. On the other hand, the volume resistivity further decreases as the crystallinity decreases.

Although the degree of substitution can be selected in a wide range depending on the reaction conditions of the substitution reaction, in the present invention, the degree of substitution is 40 to 70.
Mole% is used. If the degree of substitution is lower than 40 mol%, it is difficult to satisfy electrophotographic properties in solvent solubility, adhesion, and volume resistivity. On the other hand, if the degree of substitution is higher than 70 mol%, reaction conditions Setting becomes difficult. The type of the substituent of the amide bond can be changed depending on the mercaptan used in the modification reaction.
Those having an ethylthiomethyl group, an isobutylthiomethyl group or the like are obtained.

In the present invention, examples of the copolymerized nylon having 6 nylon as a constituent material as a base material to be modified include the following. Nylon 6-6 (Ube Nylon 2020B: manufactured by Ube Industries, Ltd.) as a binary nylon, and Nylon 6-66-610 (Amilan C) as a ternary nylon
M4000: manufactured by Toray Industries, Inc., nylon 6-66-12 (Diamid T171 and D250, Daicel Huls Co., Ltd.)
Ube Nylon 6021X21: Ube Industries, Ltd., Platabond M995F: Nippon Rilsan Co., Ltd.), Nylon 6-610
-12 (Daiamide T451: manufactured by Daicel Huels Co., Ltd.),
Nylon 6-66-bis (4-aminocyclohexyl) methane-6 (Ultramid 1C: manufactured by BASF), as a quaternary nylon, nylon 6-66-610-12 (Alamine CM8000: manufactured by Toray Industries, Inc.), special As copolymerized nylon, 11 series special copolymerized nylon (Platabond M1276T: manufactured by Nippon Rilsan Co., Ltd.), special copolymerized nylon (Platabond MX117)
8, Pradabond MX1602 and Platabond MX1603: manufactured by Nippon Rilsan Co., Ltd.).

In the present invention, the thickness of the intermediate layer is generally 0.01 to 5 μm.
m, preferably 0.2 to 2 μm. In order to form the intermediate layer, it is necessary to prepare a coating solution, but as a solvent for dissolving the modified polyamide, for example, ethanol, methanol, propanol,
Alcohols such as butanol can be used alone or as a mixture, or as a mixture of these with water.

When applying the coating liquid, for example, a dip coating method, a spray coating method, a blade coating method, a spinner coating method, a bead coating method, a coating method such as a curtain coating method can be used, and drying is performed at 10 to 150 ° C. , Preferably 20 to 100 ° C
At a temperature in the range of 5 minutes to 5 hours, preferably 10 minutes to 2 hours.

In the electrophotographic photoreceptor of the present invention, by the function of the polar group substituted by the amide bond of the modified polyamide resin,
The volume resistance of the intermediate layer can be controlled to a low level so that the electrophotographic characteristics of the photosensitive layer do not deteriorate. The volume resistance is less dependent on temperature and humidity, and the dependence of electrophotographic characteristics on temperature and humidity is improved.

A photosensitive layer is provided on the intermediate layer, and the photosensitive layer may have a single-layer structure or a laminated structure. In the case of a single-layer structure,
Examples include a dye-sensitized ZnO photosensitive layer and a CdS photosensitive layer, and a photosensitive layer in which a charge generating substance is dispersed in a charge transporting substance.

Further, in the case of a laminated structure, a layer in which functions are separated into a charge generation layer and a charge transport layer may be mentioned. The order of lamination of the charge generation layer and the charge transport layer on the substrate may be any order.

The charge generation layer is formed by dispersing a charge generation material in a binder resin as needed. Examples of the charge generating material include selenium and selenium alloys; CdS, CdSe, CdSSe, ZnO, and Zn.
Inorganic photoconductors such as S; metal or metal-free phthalocyanine pigments; azo pigments such as bisazo pigments and trisazo pigments; squarium compounds; azulhenium compounds; perylene pigments; indigo pigments; quinacridone pigments; A xanthene dye; a charge transfer complex composed of poly-N-vinylcarbazole and trinitrofluorenone; a eutectic complex composed of a pyrylium salt dye and a polycarbonate resin.

Known binder resins include, for example, polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylate polymer or copolymer, vinyl acetate polymer or copolymer, cellulose ester or ether, polybutadiene, polyurethane, epoxy Resin or the like is used.

The charge transport layer is composed mainly of a charge transfer material. The charge transfer material is not particularly limited as long as it is transparent to visible light and has a charge transport ability. Specifically, imidazole, pyrazoline, thiazole, oxadiazole, oxazole , Hydrazone, ketazine, azine, carbazole, polyvinylcarbazole and the like, and derivatives thereof, triphenylamine derivative, stilbene derivative, benzidine derivative and the like. If necessary, a binder resin is used in combination.As the binder resin, for example, polycarbonate,
Polyarylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylate, styrene-methacrylate copolymer and the like can be mentioned.

Examples Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 60 parts by weight of terpolymer nylon (nylon 6-66-)
Bis (4-aminocyclohexyl) methane-6) (trade name: Ultramid 1C, manufactured by BASF) was dissolved in 150 parts by weight of 99% formic acid and stirred at room temperature. On the other hand, 60 parts by weight of paraformaldehyde was gradually added to and dissolved in 120 parts by weight of a sufficiently cooled ethyl mercaptan (a solution in which a trace amount of sodium hydroxide was previously dissolved. The obtained paraformaldehyde-ethyl mercaptan was dissolved. The solution was added to the above ternary copolymerized nylon solution, stirred for about 1 hour and reacted, and then the reaction mixture was mixed with 1200 parts by weight of acetone-water (volume ratio).
1: 1), and further neutralized by dropwise addition of 28% aqueous ammonia. As a result, a white powdery resin was precipitated. After separation, water washing was repeated to remove excess ammonia. The obtained partially methylmercaptomethyl-substituted copolymer nylon had a degree of substitution of 50 mol%.

The obtained partially methylmercaptomethyl-substituted copolymerized nylon was treated with methanol / n-butanol / water (weight ratio 5: 3: 0.
The coating solution was prepared by dissolving in the mixed solvent of 5) so that the solid content concentration became 10% by weight.

The above coating solution was applied on an aluminum pipe by a dip coating method, and was dried by heating at 100 ° C. for 5 minutes.
A μm intermediate layer was formed.

Next, 87 parts by weight of granular trigonal selenium and vinyl chloride-
Vinyl acetate copolymer (trade name: Solution Vinyl
VMCH, manufactured by Union Carbide Co.)
A solution dissolved in 200 parts by weight of butyl was dispersed by an attritor for 24 hours. Next, 57 parts by weight of n-butyl acetate was added to 30 parts by weight of the obtained dispersion to dilute it to obtain a dip coating solution.

Using this dip coating solution, dip coating was performed on an intermediate layer on an aluminum pipe. That is, the aluminum pipe on which the intermediate layer is formed is immersed in the coating solution in the dip coating tank,
The film was pulled up at a rate of 100 mm / min, dried by heating at 100 ° C. for 5 minutes, and a charge generation layer having a thickness of about 0.1 μm was laminated.

Next, N, N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine
10 parts by weight of 10 parts by weight of the polycarbonate Z resin were dissolved in 80 parts by weight of monochlorobenzene to prepare a coating liquid for forming a charge transport layer. This coating solution was applied on the charge generation layer and dried with hot air at 100 ° C. for 60 minutes to form a charge transport layer having a thickness of 25 μm.

The electrophotographic photoreceptor thus manufactured is mounted on a copying machine (FX5030 modified machine, manufactured by Fuji Xerox Co., Ltd.),
After adjusting the dark portion potential VD to be -800 V, 2 erg / cm
² was exposed to light, and the light portion potential VL was measured. After that, an endurance test of 100,000 copies was performed, and the dark potential VD
And the change in the light portion potential VL were measured. At the same time, the image quality was evaluated. The results are shown in Table 1.

Comparative Example 1 Unmodified quaternary copolymer nylon (6-66-610-1)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1, except that the intermediate layer was formed using 2 copolymer nylon) (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.). Was. The results are shown in Table 1.

Effect of the Invention Since the electrophotographic photoreceptor of the present invention has the intermediate layer composed of the above-mentioned constituent components, the humidity dependency of the development contrast is improved, the residual potential is reduced, and the photosensitive material has high sensitivity and long life. The obtained copy image has an excellent effect that image defects such as white spots, black spots, rough edges, pinholes and the like are hardly generated.

Claims (1)

(57) [Claims] 1. An electrophotographic photoreceptor comprising a substrate, an intermediate layer and a photosensitive layer, wherein the intermediate layer comprises a modified polyamide resin, and the modified polyamide resin has an amide bond of 40 to 40.
An electrophotographic photoreceptor characterized in that 70 mol% is mainly composed of nylon 6 having a substituted amide bond represented by the following structural formula or copolymer nylon containing nylon 6 as a constituent. (In the formula, R represents a methyl group, an ethyl group, a propyl group, or a butyl group.)