JPH06202350A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive body giving a clear image. CONSTITUTION:When an undercoat layer 2, an electric charge generating layer 3 and an electric charge transferring layer 4 are successively laminated on a dielectric substrate 1 to obtain an electrophotographic sensitive body, oligosaccharide, polysaccharide, polyvinyl alcohol or one of derivs. of them each having cyanoethyl groups substd. at >=60% rate of substitution and 10-20C satd. fatty acid ester groups substd. at 5-40% rate is used as a resin binder for the electric charge generating layer 4. The objective electrophotographic sensitive body is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to an electrophotographic photosensitive member widely used in printers, facsimiles and the like.

[0002]

2. Description of the Related Art Generally, an electrophotographic photosensitive member has a structure in which an undercoat layer, a charge generating layer, and a charge transporting layer are laminated in this order on a conductive support. The substance is dispersed and carried in the binder resin,
It has a function of generating electrons and holes from the charge-generating substance when it is exposed to light. Therefore, when the surface of the charge transport layer is negatively charged in advance and then imagewise exposure is performed, holes are generated in the charge generation layer exposed to the light, and the holes pass through the layer to reach the surface of the charge generation layer. It reaches and neutralizes the negative charge of that part. As a result, an electrostatic latent image corresponding to the image is formed on the surface of the charge transport layer, and after developing this with a toner having a positive charge, the image is transferred and fixed on paper to complete copying.

[0003]

Polyester, polyvinyl acetal, polyurethane, silicone resin, epoxy resin and the like have been used as the binder resin for the charge generation layer, but all of these resins have a high resistance value. , Holes generated from the charge generation material tend to remain in the charge generation layer. Therefore, the attenuation of the bright part potential is hindered,
The sharpness of the image was impaired. Therefore, an object of the present invention is to provide an electrophotographic photosensitive member having a clear image.

[0004]

As a result of investigations for solving the above-mentioned problems, the present inventors have found that an undercoat layer is formed on a dielectric support,
In the electrophotographic photoreceptor having a structure in which a charge generation layer and a charge transport layer are laminated in this order, a binder resin for the charge generation layer is an oligosaccharide, a polysaccharide, polyvinyl alcohol or a derivative thereof, and the substitution ratio of the cyanoethyl group is 60. % Or more, the substitution rate of the saturated fatty acid ester group having 10 to 20 carbon atoms is 5
The inventors have found that it is sufficient to use a material in which the content is replaced with -40%, and have reached the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 illustrates an electrophotographic photosensitive member according to the present invention. Reference numeral 1 is a conductive support, 2 is an undercoat layer, 3 is a charge generation layer, and 4 is a charge transport layer. The conductive support 1 may be a drum-shaped or sheet-shaped metal made of aluminum, iron, copper or the like, or a drum-shaped or sheet-shaped conductive material obtained by dispersing or applying a conductive metal compound, a metal or the like in a resin. Examples thereof include a drum-shaped or sheet-shaped insulating material in which aluminum, nickel, indium tin oxide, or the like is vapor-deposited or laminated.

For the next undercoat layer 2, polyurethane, polyamide, polyester, polyvinyl alcohol, epoxy resin, casein, methylcellulose, nitrocellulose, phenol resin and a polymer as a binder resin for the charge generating layer described later are used. In order to form the undercoat layer 2, other resins and additives are added to the above resin, if necessary, and then dissolved in a solvent such as acetone, N, N′-dimethylformamide, methyl ethyl ketone, γ-butyrolactone, Dip coating method, spray coating method,
Conductive support 1 by a conventional coating method such as a spin coating method, a blade coating method, or a roller coating method.
This is done by evaporating the solvent after coating on. The thickness of the undercoat layer 2 is preferably 0.05 to 5.00 μm.

The charge generation layer 3 is prepared by adding other resins and additives to the binder resin for the charge generation layer, if necessary, and then dissolving this in a solvent and further adding and dispersing the charge generation substance. The dispersion liquid is formed on the undercoat layer 2 by coating and drying. This binder resin is an oligosaccharide, a polysaccharide, a hydroxyl group of polyvinyl alcohol or a derivative thereof, which is substituted with a cyanoethyl group and a saturated fatty acid ester group having 10 to 20 carbon atoms, and the substitution ratio of the cyanoethyl group is 60% or more, The substitution rate of the saturated fatty acid ester group having 10 to 20 carbon atoms needs to be 5 to 40%. In this resin, when the cyanoethyl group substitution rate is less than 60%, the saturated fatty acid ester group substitution rate exceeds 40%, or the saturated fatty acid ester group has more than 20 carbon atoms, the resistance value remarkably increases. When the substitution rate of the saturated fatty acid ester group is less than 5% or the number of carbon atoms is less than 10, the resistance value varies largely with temperature, and in any case, the object of the present invention cannot be achieved. Examples of the saturated fatty acid ester group having 10 to 20 carbon atoms include linear alkyl ester groups such as decanoyl, lauroyl, myristoyl, palmitoyl and stearoyl, and branched alkyl ester groups such as isomyristoyl, isopalmitoyl and isostearoyl. To be done. As the solvent used for dissolving the binder resin and the like, acetone, N, N′-dimethylformamide, methyl ethyl ketone, γ-butyrolactone and the like, and as the charge generating substance, titanium oxide phthalocyanine, metal-free phthalocyanine, copper phthalocyanine and the like. Examples thereof include phthalocyanine dyes, azo dyes such as chlorodiablue, and quinone pigments such as pyrene and quinone. For the coating of the dispersion on the undercoat layer, a usual coating method such as a dip coating method, a spray coating method, a spin coating method, a blade coating method or a roller coating method can be applied. The thickness of the charge generation layer is 0.05-5.00μ.
m is preferred.

The above-mentioned binder resin is prepared by reacting a raw material oligosaccharide, polysaccharide, polyvinyl alcohol or a derivative thereof with acrylonitrile in the presence of an alkali catalyst to prepare a cyanoethylated product having a desired degree of cyanoethyl group substitution. It can be obtained by esterification. The oligosaccharides, polysaccharides, polyvinyl alcohol or their derivatives include oligosaccharides such as saccharose, sorbitol and xylitol, polysaccharides such as cellulose, pullulan and starch, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl starch and hydroxypropyl pullulan. Examples thereof include hydroxyalkylated polysaccharides such as, dihydroxypropyl cellulose, dihydroxypropyl pullulan, dihydroxyalkylated polysaccharides such as dihydroxypropyl starch, and polyvinyl alcohol. The above-mentioned cellulose includes regenerated cellulose, powdered cellulose, microcrystalline cellulose and the like, and the above starch or its derivative includes potato starch, rice starch, corn starch, dextrin, amylose, amylopectin and the like. Examples of the alkali catalyst include hydroxides such as sodium hydroxide and potassium hydroxide, alcoholates such as sodium ethylate, salts such as sodium carbonate and ammonium hydroxide, and metallic sodium.

The following esterification is carried out by dispersing or dissolving the obtained cyanoethylated product in a solvent and then in the presence of a hydrochloric acid scavenger, an esterifying agent having a saturated fatty acid group having 10 to 20 carbon atoms, for example, stearoyl chloride. , Palmitoyl chloride,
It is carried out by adding a fatty acid chloride such as lauroyl chloride and reacting it. Examples of the solvent used in this reaction include acetone, dimethylformamide, dimethylsulfoxide, methylethylketone, dimethylacetamide, pyridine and the like. As the hydrochloric acid scavenger, a basic organic solvent such as pyridine or triethylamine is used. The esterification reaction is preferably carried out at a temperature of 100 ° C or lower. The amount of the esterifying agent added varies depending on the intended degree of substitution, but the number of moles of saturated fatty acid groups having 10 to 20 carbon atoms contained in the esterifying agent relative to the hydroxyl group of the raw material is 1.0 mol or more, and particularly 1.5 mol or more. preferable. If this is less than 1.0 mol with respect to the raw material hydroxyl group, the degree of modification cannot be sufficiently increased.

The charge transport layer 4 is a binder resin in which a charge transport material is dispersed, and the charge transport material is added to a solution obtained by dissolving the binder resin in a solvent, and the charge transport layer 4 is coated and dried. Is formed by Polyester, polycarbonate, polysulfone, styrene-methacrylate copolymer resin or the like can be used as the binder resin, and polycyclic aromatic compounds such as anthracene, nitrogen-containing heterocyclic compounds such as carbazoyl, and hydrazone compounds can be used as the charge transport material. Examples are triarylamine compounds and stilbene compounds. As the coating method of the above solution, the same method as used for forming the undercoat layer and the charge generation layer can be adopted. The thickness of the charge transport layer is preferably 5 to 30 μm.

[0011]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to synthesis examples, examples and comparative examples, but the present invention is not limited to the description of the examples. Synthetic Example 1 40 g of cyanoethyl pullulan: cyanoresin CR-S (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) containing 2.6 mol of cyanoethyl group (substitution rate 87%) per anhydrous glucose unit was dissolved in 200 g of acetone, and then 50 g of pyridine was added. In addition, with stirring at 70 ° C, 33.1 g of lauroyl chloride was added dropwise over about 20 minutes,
The reaction was carried out for 4 hours. After cooling, 10 g of methanol was added to stop the reaction, and then the reaction solution was poured into methanol with stirring to obtain a precipitate. The obtained precipitate was washed with hexane and dried under vacuum at 80 ° C for 12 hours to give a pale yellow 45.4
g of purified product was obtained. Elemental analysis of this product revealed that it had a nitrogen content of 10.17% and was cyanoethyl pullulan laurate in an amount of 0.32 mol per anhydroglucose unit (substitution rate: 11%).

Synthetic Example 2 Instead of cyanoethyl pullulan in Synthetic Example 1, cyanoethyl hydroxyethyl cellulose containing 2.3 mol of cyanoethyl group (substitution rate 77%) and 1.45 mol of hydroxyethyl group per anhydrous glucose unit: cyanoresin.
CR-E (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) 30g, stearoyl chloride 49.7g in place of lauroyl chloride, the same reaction and post-treatment were carried out. g was obtained. Elemental analysis of this product revealed that it had a nitrogen content of 6.19% and was 0.65 mol (replacement ratio: 22%) of cyanoethyl hydroxyethyl cellulose stearate per anhydrous glucose unit.

Synthesis Example 3 Cyanoethyl polyvinyl alcohol in which 77% of the hydroxyl groups of polyvinyl alcohol are replaced with cyanoethyl groups in place of cyanoethyl pullulan in Synthesis Example 1: cyanoresin CR-V (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) 30 g The reaction and post-treatment were carried out in the same manner except that 56 g of palmitoyl chloride was used instead of lauroyl chloride to obtain 39.8 g of a pale yellow purified product. Elemental analysis of this product revealed that it had a nitrogen content of 8.76% and was cyanoethylpolyvinylalcohol palmitate containing 16% (substitution rate: 16%) of the hydroxyl groups of polyvinyl alcohol.

Synthesis Example 4 120 g of regenerated cellulose obtained by saponifying cellulose diacetate L-20 (trade name, manufactured by Daicel Chemical Industries Ltd.) was added to acetone 12
Disperse in 00 g, add 270 g of 10% sodium hydroxide aqueous solution and stir at room temperature for 30 minutes, then add 87.7 g of glycidol dropwise,
The reaction was carried out at 50 ° C for 4 hours. Then, 215 g of 20% acetic acid aqueous solution was added to stop the reaction. The product was collected by filtration, washed twice with 1000 g of a mixed solution of water / acetone / methanol 1: 2: 2, washed with acetone, and collected by filtration. The product obtained is 9
Dissolve in 00g of water, 200g of 25% sodium hydroxide solution
Was added and the mixture was stirred at 25 ° C for 30 minutes. Then, 790 g of acrylonitrile and 660 g of acetone were added, and the mixture was kept at 15 ° C for 3 hours, then heated to 30 ° C and reacted for 6 hours. The reaction was stopped by adding 240 g of 20% acetic acid aqueous solution, and the reaction solution was poured into a large amount of water to crystallize the product, which was dried at 80 ° C for 8 hours and then 175 g.
The product was obtained. The product was cyanoethyldihydroxypropylcellulose containing 2.7 mol of cyanoethyl groups (substitution rate 79%) and 0.45 mol of dihydroxypropyl groups per anhydroglucose unit. After performing the reaction and the post-treatment in the same manner as in Synthesis Example 1 except that 30 g of this cyanoethyldihydroxypropyl cellulose was used, 38.9 g of a milky white purified product was obtained. Elemental analysis showed that the nitrogen content was 8.35%,
It was 0.41 mol (12% substitution rate) of cyanoethyl dihydroxypropyl cellulose stearate.

Example 1 Methoxymethylated nylon resin: Toresin EF-30T (manufactured by Teikoku Kagaku Sangyo Co., Ltd., 5 parts by weight) was dissolved in 95 parts by weight of methanol, and this was applied on an aluminum pipe by dip coating, and then 100 It was dried at ℃ for 1 hour to form an undercoat layer having a film thickness of 1 µm. Next, 10 parts by weight of the resin obtained in Synthesis Example 1 and 10 parts by weight of copper phthalocyanine were put together with 500 parts by weight of γ-butyrolactone in a porcelain ball mill and dispersed and mixed for 10 hours. After drying at 100 ° C. for 2 hours, a charge generation layer having a film thickness of 0.5 μm was formed. Further, 10 parts by weight of the hydrazone derivative represented by the structural formula of the following chemical formula 1 and 10 parts by weight of styrene-methyl methacrylate copolymer MS-200 (trade name, manufactured by Iron and Steel Chemical Co., Ltd.) are dissolved in 80 parts by weight of toluene. Dip coating on the charge generation layer at 100 ℃
After drying for 2 hours, a charge transport layer having a film thickness of 20 μm was formed to obtain an electrophotographic photoreceptor. When the electrophotographic photosensitive member thus obtained was attached to a copying machine and electrophotographic characteristics were evaluated, a clear copy of the image was obtained.

[0016]

[Chemical 1]

Examples 2, 3 and 4 An electrophotosensitive material was prepared in the same manner as in Example 1 except that the resins obtained in Synthesis Examples 2, 3 and 4 were used as the binder for the charge generation layer. When evaluated to,
A clear copy of the image was obtained.

Comparative Example 1 Polyvinyl butyral: Elex BM-5 (manufactured by Sekisui Chemical Co., Ltd., trade name) was used as a binder for the charge generation layer, and an electrophotosensitive material was prepared in the same manner as in Example 1,
When evaluated in the same manner, the image of the obtained copy was unclear.

[0019]

Since the electrophotographic photoreceptor of the present invention uses a resin having a relatively low electric resistance as the binder resin for the charge generating layer, the charge generated during exposure does not remain in the charge generating layer and is clear. It will give a nice image.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Conductive support, 2 ... Undercoat layer, 3 ... Charge generation layer, 4
Charge transport layer.

Claims (1)

[Claims] 1. An undercoat layer, a charge generation layer, and a dielectric support on a dielectric support.
In the electrophotographic photoreceptor having a structure in which the charge transport layer is laminated in this order, as a binder resin for the charge generation layer, oligosaccharides, polysaccharides, polyvinyl alcohol or derivatives thereof, the substitution rate of cyanoethyl group is 60% or more, carbon Number 10 ~
An electrophotographic photoreceptor comprising a saturated fatty acid ester group having a substitution rate of 5 to 40%.