JP2611708B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor,
More specifically, the present invention relates to an electrophotographic photoreceptor having excellent image quality, electrical characteristics, and stability against environmental changes, and having excellent printing durability, desensitizing reactivity, and desensitizing film forming performance as an electrophotographic lithographic printing plate.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member composed of a conductive support and a photoconductive layer is used for image formation by charging, exposure and development, which are general electrophotographic processes. The method used as a printing plate is widely used. The binder resin used to form the photoconductive layer of the electrophotographic photoreceptor has its own film forming property, adhesiveness of the formed photoconductive layer to the conductive support, and binding of the inorganic photoconductive powder. It has good dispersibility in the resin and has suitable image quality and electrical properties as an electrophotographic photoreceptor, and can maintain its performance stably without being affected by environmental changes during imaging. is necessary.

It has been known that silicone resins, alkyd resins, acrylic resins (such as acrylate copolymers), and mixtures thereof, have been used as resins for electrophotographic photoreceptors since ancient times. However, when these conventional resins are used, 1) the affinity with the inorganic photoconductive powder is insufficient, and the dispersibility of the coating liquid is poor; 2) the reproducibility of the copied image is poor; ) Very susceptible to environmental changes during imaging (from high temperature and high humidity to low temperature and low humidity). 4) When used as a lithographic printing plate, the film strength and adhesion of the photosensitive layer are insufficient, and peeling of the photosensitive layer occurs during printing. 5) The lithographic printing plate has a low reactivity with the desensitizing solution, and the printed matter is soiled.

As an improvement of the binder resin of the photoconductive layer, for example, Japanese Patent Application Laid-Open No. Sho 60-10254 discloses an acrylic resin having an acid value of 4 to 50 and a component having an average molecular weight distribution of 10 ³ to 10 ^4.
There is disclosed a method of improving image quality, electric characteristics, moisture resistance, and the like by using components having a distribution of 10 ^{4 to} 2 × 10 ⁵ in combination. Research on lithographic printing plates using electrophotographic photoreceptors has been earnestly conducted, and a binder resin for a photoconductive layer that has both imageability and electrical characteristics as an electrophotographic photoreceptor and printability as a printing plate. For example, in Japanese Patent Publication No. 50-31011, a (meth) acrylate monomer is copolymerized with another monomer in the presence of fumaric acid, and has a molecular weight MW of 1.8.
And × 10 ⁴ ~10 × 10 ⁴ a glass transition point Tg 10 to 80 ° C. of the resin, that a combination of a copolymer composed of a monomer other than (meth) acrylate monomer and fumaric acid, MatatokuHiraki JP-A-54-20735 and JP-A-57-202544 disclose the use of a quaternary or pentameric copolymer containing acrylic acid and hydroxy (meth) acrylate.
In Japanese Patent No. 68046, the use of a ternary copolymer containing a (meth) acrylic acid ester having a C6-C6 alkyl group as a substituent and a carboxylic acid-containing vinyl monomer is known as the desensitizing property of the photoconductive layer. Is said to be effective in improving

[0005] However, even if the resin is considered to be effective in the above-mentioned image properties, electrical properties, moisture resistance, etc., it is found that the electrical properties such as chargeability, light decay, dark decay retention, etc. , Image quality such as background dirt and image density of non-image part, stability against environmental change during imaging (from high temperature and high humidity to low temperature and low humidity)
Are not satisfactory in practical use, and the film strength on the surface of the photoconductive layer is weak and the smoothness is high, so that indentations such as abrasions are generated on the surface, which may cause stains on imaged and printed matter. there were.

Further, even if a binder resin which is considered to be effective for improving the desensitization property for an electrophotographic lithographic printing plate is actually evaluated, it is insensitive to hand etching having a high desensitization treatment effect. In the case of performing the degreasing treatment, it is the degree that a slight point-like background stain is generated, but when the desensitization treatment is performed with an etching processor having a low desensitizing effect that has been widely used in recent years, Uniform soiling occurs over the entire surface.

[0007] Therefore, conventionally, in the case of performing desensitization processing using an etching processor, as a method of relieving background contamination, there is a two-pass method in which a plate once processed by the etching processor is processed again by the etching processor. However, the two-pass method is effective for the ground stain which is uniform over the entire surface, but is less effective for the point-like background stain, and the two-pass process is more effective than the hand etching process. Also, the printed matter tends to have a lot of dot stains.

[0008]

SUMMARY OF THE INVENTION Even with a binder resin for an electrophotographic photosensitive member having improved electrical characteristics, image properties, moisture resistance, etc., the environment at the time of imaging has changed from high temperature and high humidity to low temperature and low humidity. In this case, it was found that it was still insufficient to maintain the performance stably, and it was further found that there were problems in the dispersibility of the coating liquid, the film strength on the surface of the photoconductive layer, the smoothness, and the like.

In the case of electrophotographic lithographic printing plates, dot-like background stains greatly affect the value of printed matter. A lithographic printing plate that does not cause bleeding is required. Further, in recent years, a plate making machine and an etching processor, or an etching processor and a printing machine, or an automatic plate making machine in which a plate making machine, an etching processor and a printing machine are integrated, and a printing system, an etching processor 1 is used as an etching processing method.
The pass-through method is preferable in terms of the process of the system, and the development of a lithographic printing plate that does not cause background stain on printed matter even in a desensitizing treatment by one pass of an etching processor is desired.

The present invention is to improve the above-mentioned problems of the conventional electrophotographic photosensitive member as follows. An object of the present invention is to provide an electrophotographic photoreceptor having excellent electrical characteristics,
Even if the environment at the time of imaging changes from high temperature and high humidity to low temperature and low humidity, it maintains stable, clear and high quality image quality,
Furthermore, as an electrophotographic lithographic printing plate, it is excellent in printing durability, hardly generates indentations such as abrasion on imaged and printed materials, and has been conventionally performed by hand etching, etching processor twice, and etching with low processing effect. To provide a lithographic printing plate having excellent desensitization reactivity and desensitized film-forming performance that does not generate spotted scum as well as uniform scum on printed matter even with a processing method using a single pass of a processor. It is.

[0011]

An object of the present invention is to provide an electrophotographic photoreceptor having a photoconductive layer mainly composed of an inorganic photoconductor and a binder resin formed on a conductive support. It contains the resin (A) and the resin (B) shown below,
The solid content weight ratio is resin (A) / resin (B) = 8-3 /
It has been found that this is achieved by an electrophotographic photoreceptor characterized by being 2 to 7.

Resin (A): a first resin composition obtained by polymerizing an acrylic monomer mixture in the presence of an alkyd resin, wherein the weight ratio of the alkyd resin to the acrylic monomer mixture is 2.5-50 / 97.5-50 resin. Resin (B): a second resin composition obtained by polymerizing an acrylic monomer mixture and having a resin acid value of 2.0 to 10.0.

The binder resin of the present invention is characterized in that a resin (A) obtained by polymerizing an acrylic monomer mixture in the presence of an alkyd resin, an acrylic monomer mixture, and an unsaturated acid copolymerized therewith. The resin (B) is obtained by adjusting the resin acid value according to the weight ratio and polymerizing the resin. When only the resin (A) of the present invention is used as the binder resin, poor dispersion of the coating liquid occurs, the presence of agglomerates on the surface of the photoconductive layer, insufficient film strength of the photoconductive layer, and a problem with respect to the conductive support. Peeling of the photoconductive layer due to insufficient adhesion of the photoconductive layer,
The surface of the photoconductive layer has a problem that the smoothness of the surface is high and indentations such as scratches are easily generated.In addition, in the electrophotographic characteristics, the image density of the captured image has an excellent performance with high image density. There are problems such as deterioration of image quality at high temperature and high humidity.

In the case of an electrophotographic planographic printing plate,
Even though the etching processor is passed only once, the printed matter has excellent performance in that the entire surface is not stained, but problems such as dot-like or partial printed stains due to agglomerates and indentations on the photoconductive layer surface occur. There is. When the resin (B) of the present invention is used alone as a binder resin, the dispersibility of the coating liquid
Although the stability to environmental changes during imaging is good, the dispersion of the photoconductive powder and the resin is too advanced, and the smoothness of the surface is high, so that indentations are generated and the electrophotographic characteristics have low image density. In addition, the electrophotographic lithographic printing plate has a problem in that dot-like background stains are generated on the printed matter by hand etching, and uniform background stains are generated on the entire surface by passing the etching processor twice.

When the resin (A) and the resin (B) are used alone as the binder resin, the resin (A) contains an alkyd resin, and the resin (B) contains a certain amount of carboxylic acid. However, the resin (A) has no affinity with the photoconductive powder, and the resin (B) has an affinity with the photoconductive powder. It is considered that the above-mentioned problem occurs because the dispersibility with the photoconductive powder is not appropriate because the dispersibility is too strong.

In the present invention, by mixing the resin (A) with the resin (B) to form a binder resin, the excellent performance of the resin (A) and the resin (B) is not impaired. An electrophotographic photoreceptor and an electrophotographic lithographic printing plate excellent in solving problems such as the dispersibility of the resin (B), the surface film strength of the photoconductive layer, the adhesion, and the smoothness were found. In particular, unexpected results were found before mixing, in which the resin (A) and the resin (B), both of which have high smoothness, were mixed and the smoothness was lowered, which could not be predicted before the practice.

The mixture of acrylic monomers used in producing the resins (A) and (B) is obtained by using acrylic acid or methacrylic acid and an alcohol having a hydrocarbon group having 1 to 12 carbon atoms. Esters, whose typical examples are hydrocarbon groups such as methyl group, ethyl group, n-butyl group, i-butyl group, t-butyl group, n-propyl group, isopropyl group, 2-ethylhexyl group, n- (Meth) acrylates such as lauryl group, cyclohexyl group, benzyl group, etc., and styrene derivatives such as styrene, α-methylstyrene, p-bromostyrene, β-chlorostyrene, Organic nitriles such as acrylonitrile, methacrylonitrile, α-methylglutaronitrile, vinyl acetate, vinyl propionate, Vinyl esters of organic acids such as vinyl lopionate and the like can be mentioned. Further, α / β-ethylenic unsaturated acids such as acrylic acid, methacrylic acid, itaconic acid and α-methylene glutaric acid can be mentioned as copolymerizable unsaturated acids. Other copolymerizable carboxylic acids such as saturated carboxylic acid, crotonic acid, and maleic acid, or hydroxyalkyl (meth)
Examples include hydroxylalkyl esters of α-β-ethylenically unsaturated carboxylic acids such as acrylates.

The resin (A) is obtained by polymerizing one or a combination of two or more of the above acrylic monomers in the presence of an alkyd resin.
For example, a known alkyd resin which is modified with a fatty acid containing alcohol and phthalic acid as main components is used. As a raw material of the fatty acid to be modified, known coconut oil, soybean oil, linseed oil, safflower oil, deer oil and the like are used, and the oil length may be any of short oil, medium oil and long oil.

The resin (B) is obtained by polymerizing one or a combination of two or more acrylic monomers in the same manner as the resin (A). However, the resin (B) is polymerized so that the resin acid value becomes 2.0 to 8.0. Adjust the amount of polymerizable unsaturated acid. The method for producing the polymer of the present invention is preferably ordinary solution polymerization. As the polymerization solvent, hydrocarbons such as toluene and xylene, alcohols such as propanol and butanol, ketones such as acetone and methyl ethyl ketone, and mineral spirits And esters such as ethyl acetate and butyl acetate, and cellosolves such as ethyl cellosolve and bityl cellosolve.

Examples of the polymerization initiator used for polymerizing the resin (A) and the resin (B) include benzoyl peroxide, cumene hydroperoxide, lauryl peroxide, cyclohexanone peroxide and t-butyl hydroperoxide. An azo compound such as a peroxide or azobisisobutyronitrile is used, but for the resin (A), a peroxide-based initiator is preferable because of the compatibility between the acrylic monomer and the alkyd resin.

If necessary, a chain transfer agent such as mercaptans can be used. It is also possible to use another resin in combination with the resin (A) and the resin (B) of the present invention, and examples thereof include an acrylic resin, an epoxy resin, a silicone resin, and a styrene resin. An acrylic resin having a low average molecular weight (for example, 10 ^{3 to} 3 × 10 ⁴ ) and a high acid value (for example, 10 to 100) may also be used.

However, when the resin used in combination has a resin acid value, the total resin acid value of the resin used in combination with the resin (B) exceeds 10.0, or the weight of the total binder resin using the resin of the present invention. If it exceeds 30% by weight, the effect of the present invention is lost. If the content of the alkyd resin of the resin (A) is less than 2.5% by weight, the image quality, especially at high temperature and high humidity, and the electrical characteristics are deteriorated. In particular, the image quality and the desensitizing property at low temperature and low humidity deteriorate.

If the resin acid value of the resin (B) is less than 2.0, the dispersibility of the coating solution, the surface strength and adhesion of the photoconductive layer, the image quality, and especially the image density at high temperature and high humidity are deteriorated. If the ratio is more than 10.0, the sensitivity is low, and the non-image portion at high temperature and high humidity deteriorates background smear and desensitization property. The weight ratio of the resin (A) to the resin (B) used in the present invention varies depending on the type, particle size, and surface condition of the inorganic photoconductor to be used, but the weight ratio of the resin (A) to the resin (B) is generally It is from 8 to 3/2 to 7, preferably from 7 to 4/3 to 6.

When the image quality is important for the electrophotographic photosensitive member, the resin (A) is less than 50% by weight. When the desensitizing property is important for the electrophotographic lithographic printing plate, the resin (A) is important. More preferably, it is more than 50% by weight. As the inorganic photoconductor material used in the present invention, zinc oxide,
Titanium oxide, zinc sulfide, cadmium sulfide, cadmium carbonate, zinc selenide, cadmium selenide, tellurium selenide, lead sulfide and the like can be used, and preferably, zinc oxide, titanium oxide and the like are used.

The total amount of the binder resin used for the inorganic photoconductor material is 10 to 100 parts by weight of the photoconductor.
It is used in a proportion of 50 parts by weight, preferably in a proportion of 15 to 30 parts by weight. In the present invention, various dyes can be used in combination as a spectral sensitizer as needed, for example, a carbonium dye, a diphenylmethane dye, a triphenylmethane dye,
Examples include xanthene dyes, phthalein dyes, polymethine dyes (oxonol, merocyanine dyes, cyanine dyes, rhodacyanine dyes, styryl dyes, etc.), phthalocyanine dyes (metals may be contained), and the like.

The photoconductive layer of the present invention is also excellent in that even when the above-described sensitizing dye is used in combination, the performance thereof is not easily changed by the sensitizing dye. If necessary for the photoconductive layer of the present invention,
Various known additives for an electrophotographic photoconductive layer such as a chemical sensitizer can be used in combination, for example, an electron-accepting compound (halogen, benzoquinone, cranyl, acid anhydride, organic carboxylic acid, etc.),
Examples include polyarylalkane compounds, hindered phenol compounds, p-phenylenediamine compounds, and the like.

The amount of these various additives is not particularly limited, but is usually 0.001 to 2.0 with respect to 100 parts by weight of the photoconductor.
Parts by weight. The coating amount of the photoconductive layer is preferably 5 to 50 g / m ² , particularly preferably 10 to 35 g / m ² , and the thickness is preferably 3 to 50 μ, particularly preferably 5 to 30 μ. The photoconductive layer according to the present invention can be provided on a conventionally known conductive support.

Examples of the conductive support include metals such as aluminum, paper, plastic sheets and the like, lamination thereof, composite bases impregnated with a low-resistance substance and the like, and conductive bases. The back surface (the surface opposite to the surface on which the photoconductive layer is provided) is provided with conductivity, and is further coated with at least one layer to further prevent moisture and curl. A water-resistant coating layer is provided on the surface of the support. Provided are those provided with at least one or more precoat layers as necessary on the surface layer of the support layer, those obtained by laminating paper on a plastic such as A1 which is a vapor-deposited substrate, and the like. .

[0029]

EXAMPLES Examples of the present invention will be described below, but the content of the present invention is not limited to these examples. Synthetic Example 1 of Resin (A) 1: A-1 Methyl methacrylate 56 parts by weight n-butyl methacrylate 36 {Hariftal 309-60 8} (manufactured by Harima Chemicals, Ltd., medium oil type alkyd resin, nonvolatile content 60) %) Add an appropriate amount of initiator to 100 ml of toluene, polymerize the solution, and add 37 parts of toluene and 10 parts of isopropyl alcohol to obtain a resin solution which is transparent, has a solid content of 40%, and has a resin acid value (Note 1) 1 2.0.

Note 1) Acid value of resin: The resin is dissolved in a mixture of alcohol and toluene, and phenolphthalein is used as an indicator, expressed as mg of potassium hydroxide required to neutralize the acid contained in 1 g of the sample. It was done. Synthesis Example 2 of Resin (A): A-2 30 parts by weight of methyl methacrylate n-butyl methacrylate 20 {haliftal 309-60 84} 100 parts of toluene was added with an appropriate amount of an initiator, and solution polymerization was carried out. The resin solution obtained by adding 10 parts of isopropyl alcohol was transparent, had a solid content of 40%, and had a resin acid value of 1.8. Synthesis Example 3 of Resin (A): A-3 58 parts by weight of methyl methacrylate n-butyl methacrylate 40 {haliftal 309-60} {100 parts of toluene}, an appropriate amount of an initiator was added thereto, and solution polymerization was carried out. The resin solution obtained by adding 10 parts of isopropyl alcohol was transparent, had a solid content of 40%, and had a resin acid value of 0.8. Synthesis Example 4 of Resin (A): A-4 Methyl methacrylate 50 parts by weight 2-ethylhexyl acrylate 30 〃Haliftal LOG42-60X 33 〃 (manufactured by Harima Chemicals, Ltd., short oil type alkyd resin, nonvolatile content 60) %) An appropriate amount of an initiator was added to 100 ml of toluene and solution polymerization was carried out. A resin solution obtained by adding 27 parts of toluene and 10 parts of isopropyl alcohol was transparent, having a solid content of 40% and a resin acid value of 1.1. Was. Synthesis Example 5 of Resin (A): A-5 Methyl methacrylate 50 parts by weight 2-ethylhexyl acrylate 30 Hariftal KL-912 33 長 (Harima Chemical Industry Co., Ltd., long oil type alkyd resin, nonvolatile content 60) %) Acrylic acid 1〃 Toluene 100 を, an appropriate amount of an initiator was added and solution polymerization was performed. The resin solution obtained by adding 27 parts of toluene and 10 parts of isopropyl alcohol was transparent, having a solid content of 40% and a resin acid value of 3%. Was .4. Synthesis Example 6 of Resin (A): A-6 20 parts by weight of methyl methacrylate n-butyl methacrylate 20 20hariftal 309-60 100 ト ル エ ン toluene 100 をThe resulting resin solution was transparent, had a solid content of 40%, and had a resin acid value of 1.9. Synthesis Example 7 of Resin (A): A-7 57 parts by weight of methyl methacrylate n-butyl methacrylate 40 {haliftal 309-60} {100 parts of toluene}, an appropriate amount of an initiator was added, and solution polymerization was carried out. Department,
The resin solution obtained by adding 10 parts of isopropyl alcohol was transparent, had a solid content of 40%, and had a resin acid value of 1.9. Synthesis Example 1 of Resin (B): B-1 Resin solution obtained by adding an appropriate amount of initiator to 56 parts by weight of methyl methacrylate, n-butyl methacrylate 36, acrylic acid 8 and toluene 100, and performing solution polymerization. Was transparent, had a solid content of 50% and a resin acid value of 6.0. Synthesis Example 2 of Resin (B): B-2 58 parts by weight of methyl methacrylate Ethyl acrylate 38〃Acrylic acid 4〃Toluene 100〃 An appropriate amount of an initiator is added, and the resin solution obtained by solution polymerization is transparent. The solid content was 50% and the resin acid value was 2.5. Synthesis Example 3 of Resin (B): B-3 52 parts by weight of 2-ethylhexyl methacrylate Ethyl acrylate 33 {acrylic acid 15} toluene 100} It was transparent and had a solid content of 50% and a resin acid value of 9.7. Synthesis Example 4: Resin (B): B-4 60 parts by weight of methyl methacrylate n-butyl methacrylate 40 {toluene 100} An appropriate amount of an initiator was added, and the resin solution obtained by solution polymerization was transparent. The solid content was 50%, and the acid value of the resin was 0.6. Synthesis Example 5 of Resin (B): B-5 Methyl methacrylate 45 parts by weight Ethyl acrylate 35 〃 Acrylic acid 20 ト ル エ ン Toluene 100 を An appropriate amount of an initiator is added, and the resin solution obtained by solution polymerization is transparent. The solid content was 50% and the resin acid value was 12.5. Examples 1 to 7 and Comparative Examples A to F Example 1 (resin solid content weight ratio A-1 / B-1 = 5/5) 25 parts by weight of resin A-1 produced in Synthesis Example 1 of resin (A) A mixture of Resin B-120〃 produced in Synthesis Example 1 of Resin (B), 100 光 of photoconductive zinc oxide, 5〃 of rose bengal (2% methanol solution) and 100〃 of toluene in a ball mill for 2 hours. Disperse and prepare the coating for the photoconductive layer, and then apply it to the electrophotographic base paper (which has been made water-resistant for lithographic printing plates) by conducting this treatment.
As a 20 g / m ^2, was coated by a wire bar, 100 ° C.
At 20 ° C and 60% RH in the dark for 24 minutes.
An electrophotographic photosensitive paper was prepared by being left for a time. Example 2 (resin solids weight ratio A-2 / B-2 = 5/5) In Example 1, resin A-2 was used instead of resin A-1.
An electrophotographic photosensitive paper was prepared in the same manner as in Example 1, except that the resin B-2 was used instead of the resin B-1. Example 3 (resin solid content weight ratio A-3 / B-3 = 5/5) In Example 1, resin A-3 was used instead of resin A-1.
An electrophotographic photosensitive paper was prepared in the same manner as in Example 1, except that the resin B-3 was used instead of the resin B-1. Example 4 (resin solid content weight ratio A-4 / B-1 = 5/5) The procedure of Example 1 was repeated, except that the resin A-4 was used instead of the resin A-1. Thus, an electrophotographic photosensitive paper was prepared. Example 5 (Resin solid content weight ratio A-5 / B-1 = 5/5) In the same manner as in Example 1, except that Resin A-5 was used instead of Resin A-1, the same operation as in Example 1 was performed. Thus, an electrophotographic photosensitive paper was prepared. Example 6 (resin solid content weight ratio A-1 / B-1 = 8/2) In Example 1, the compounding amount of resin A-1 was changed to 40 parts by weight, and the compounding amount of resin B-1 was changed to 8 parts by weight. Other than changing, the first embodiment
An electrophotographic photosensitive paper was prepared in the same manner as described above. Example 7 (resin solid content weight ratio A-1 / B-1 = 3/7) In Example 1, the compounding amount of resin A-1 was changed to 15 parts by weight, and the compounding amount of resin B-1 was changed to 28 parts by weight. Other than changing, the first embodiment
An electrophotographic photosensitive paper was prepared in the same manner as described above. Comparative Example A (Resin A-1 alone) The same operation as in Example 1 was carried out except that in Example 1, only 50 parts by weight of resin A-1 was used instead of resin A-1 and resin B-1. Electrophotographic paper was made. Comparative Example B (resin solid content weight ratio A-1 / B-1 = 9/1) In Example 1, the compounding amount of resin A-1 was changed to 45 parts by weight, and the compounding amount of resin B-1 was changed to 4 parts by weight. Other than changing, the first embodiment
An electrophotographic photosensitive paper was prepared in the same manner as described above. Comparative Example C (Resin B-1 alone) In the same manner as in Example 1, except that only 40 parts by weight of resin B-1 was used instead of resin A-1 and resin B-1. Electrophotographic paper was made. Comparative Example D (resin solid content weight ratio A-1 / B-1 = 2/8) In Example 1, the compounding amount of resin A-1 was changed to 10 parts by weight, and the compounding amount of resin B-1 was changed to 32 parts by weight. Other than changing, the first embodiment
An electrophotographic photosensitive paper was prepared in the same manner as described above. Comparative Example E (Resin solid content weight ratio A-6 / B-1 = 5/5) In the same manner as in Example 1, except that Resin A-6 was used instead of Resin A-1, the same operation as in Example 1 was performed. Thus, an electrophotographic photosensitive paper was prepared. Comparative Example F (resin solids weight ratio A-7 / B-1 = 5/5) The same operation as in Example 1 was performed, except that resin A-7 was used instead of resin A-1. Thus, an electrophotographic photosensitive paper was prepared. Comparative Example G (resin solid content weight ratio A-1 / B-4 = 5/5) The same operation as in Example 1 was performed, except that resin B-4 was used instead of resin B-1. Thus, an electrophotographic photosensitive paper was prepared. Comparative Example H (resin solid content weight ratio A-1 / B-5 = 5/5) The same operation as in Example 1 was performed, except that resin B-5 was used instead of resin B-1. Thus, an electrophotographic photosensitive paper was prepared.

The image quality of the electrophotographic photosensitive paper was examined by changing the environment at the time of image pickup. Further, the surface smoothness, electric characteristics, printability and printing durability when used with a lithographic printing plate were examined.

[0032]

[Table 1]

[0033]

[Table 2]

Note 2) Image properties: After leaving the obtained electrophotographic photosensitive paper for one day and night under each environmental condition, the plate making machine AP-
10EX, developer AP-10 set (Iwasaki Tsushinki Co., Ltd.
Imaging, development and fixing. Note 3) Sensitivity: Exposure scale at which the best image on electrophotographic photosensitive paper is obtained. The smaller the value, the faster the sensitivity. Note 4) Image density: The maximum value of a solid portion of a captured image measured by a Macbeth reflection densitometer (RD-514, manufactured by Macbeth Co., Ltd., USA). The higher the value, the higher the image density. Note 5) Background stain on non-image portion: Background stain on a non-image portion of a captured image was visually evaluated.

The evaluation criteria are 良好 good, Δ somewhat bad, × bad. Note 6) Smoothness: A value obtained by measuring the smoothness of the obtained electrophotographic photosensitive paper surface using a Beck smoothness tester (manufactured by Kumagaya Riki Kogyo Co., Ltd.) under the condition of an air capacity of 10 cc. Is higher, the smoothness is higher.

In the case of the photoconductive layer using the zinc oxide of the embodiment, the smoothness of 50 to 200 sec is appropriate, the aggregate is easily present in less than 50 sec, and the indentation is apt to be generated in more than 200 sec. Note 7) Electrical characteristics: Corona discharge at -6kv for 5 seconds using an electrostatic charge tester (EPA-8100, manufactured by Kawaguchi Electric Works) in a dark room of 20% and 60% RH for 5 seconds Leave it alone
The surface potential (charge amount) at this time was measured. Next, the potential V60 after standing still in the dark for 60 seconds was measured, and the retention of the potential after dark decay for 55 seconds, that is, the dark decay retention, was determined by (V60 / V5) × 100 (%). Was. Note 8) Printability: Plate making under the same conditions as 20% and 60% RH in Note 2), desensitizing solution V etch solution (Iwasaki Communication Equipment Co., Ltd.)
Is used to perform de-sensitizing treatment by hand-etching and etching processor (manufactured by Ricoh Co., Ltd.) once, and prints it as a lithographic printing plate with a printing machine (Tokyo Aviation Instruments Co., Ltd. Besty-4700CD). Was carried out, and the background stain (including the stain due to the impression) of the non-image portion of the printed matter was visually evaluated.

The evaluation criteria are 良好 good, Δ somewhat bad, × bad. Note 9) Printing durability: 7000 sheets are printed under the same conditions as in the hand etching process in Note 8), and the number of printable sheets is indicated without causing any problem in the image quality of the image area. Indicates good.

As shown in Table 1, the electrophotographic photoreceptor of the present invention had a good image density of a picked-up image, a good background stain on a non-image portion, and a good stability against environmental changes. Furthermore, as shown in Table 2, the photoconductive layer surface has good smoothness and good electrical properties,
Even when the lithographic printing plate was subjected to hand etching and desensitization treatment by one pass through an etching processor, no background stain was observed on the printed matter and the printing durability was good.

Comparative Example A using only the resin (A) of the present invention
Has a high image density, but the image quality at high temperature and high humidity is particularly poor.The smoothness of the photoconductive layer, the film strength, and the adhesiveness are also weak. Then, the printed matter was stained by an indentation, and the photoconductive layer was peeled off during printing.
Comparative Example B, in which the resin (A) of the present invention has a high solid content weight ratio, has higher performance than Comparative Example A,
The image quality at high temperature and high humidity, the smoothness of the photoconductive layer, the film strength, the adhesiveness, the dirt due to the indentation on the imaged and printed matter, and the peeling of the photoconductive layer during printing are still insufficient.

Comparative Example B using only the resin (B) of the present invention
Has good stability against environmental changes,
In particular, the background of printed matter is inferior. Resin (B) of the present invention
Comparative Example D having a higher solid content weight ratio than Comparative Example C has higher performance, but image density and background smear of printed matter are still insufficient. In Comparative Examples E and F in which the amount of the alkyd resin was increased or decreased from the resin (A) of the present invention, the background stain and the smoothness of the non-image area were deteriorated. In Comparative Example D, in which the background stain on the image area was deteriorated and reduced, the image quality and electric characteristics at high temperature and high humidity were deteriorated.

In Comparative Examples G and H in which the resin acid value was increased or decreased from the resin (B) of the present invention, the background smear, smoothness and printability of the non-image area were deteriorated. In Comparative Example F, the image density and electrical characteristics deteriorated when wet, the photoconductive layer peeled off during printing, and the increased image density, soiling of the non-image area at high temperature and high humidity, and printability deteriorated. did. From the above,
Only when the binder resin of the present invention is used, an electrophotographic photosensitive member that satisfies image properties, electrical properties, printability, printing durability, and smoothness of the photoconductive layer surface can be obtained.

[0042]

According to the present invention, an electrophotographic photoreceptor has excellent image quality, electrical characteristics, and stability against environmental changes, and furthermore has excellent printing durability and excellent indentation such as abrasion as a lithographic printing plate. Even with a processing method using a single pass of an etching processor with low surface smoothness and low processing effect that does not easily occur on printed matter, excellent desensitizing reactivity that does not generate not only uniform background stains but also dot-like background stains on printed matters. An electrophotographic photosensitive member having a desensitized film forming performance can be obtained.

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member having a photoconductive layer mainly composed of an inorganic photoconductor and a binder resin formed on a conductive support, wherein the binder resin is a resin (A) shown below. ) And a resin (B), wherein the weight ratio of the solid content of the resin (A) / the resin (B) is 8 to 3/2 to 7; Resin (A): a first resin composition obtained by polymerizing an acrylic monomer mixture in the presence of an alkyd resin, wherein the weight ratio of the alkyd resin to the acrylic monomer mixture is 2.5. ~ 50 / 97.5 ~ 50 resin. Resin (B): a second resin composition obtained by polymerizing an acrylic monomer mixture and having a resin acid value of 2.0 to 10.0.