JPH0566580A - Electrophotographic printing original plate - Google Patents

Abstract

PURPOSE:To provide the electrophotographic printing original plate which is sufficiently improved in stable reproducibility, is excellent particularly in fine line reproducibility and shadow part reproducibility, is further not contaminated any more in printing, is decreased in remaining of pigments in elution even by using a fatigued eluting liquid, is wide in handling latitude under a white fluorescent lamp and has an excellent safe light characteristic. CONSTITUTION:This electrophotographic printing original plate is obtd. by forming a toner image by using an electrophotographic system on a printing original plate provided with a photoconductive layer on an aluminum base and by eluting non-image parts to make the plate. The compsn. of the above- mentioned photoconductive layer contains a photoconductive material, o- naphthoquinone diazide-4-sulfonate or amide compd. and a high polymer compd. The more preferable embodiment is that the aluminum base is subjected to a sand graining treatment and anodic oxidation treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printing plate produced by using an electrophotographic method. More specifically, stable reproducibility is improved, printing stains are eliminated, and elution can be performed with a fatigued eluate. And an electrophotographic printing original plate having improved safelight property.

[0002]

BACKGROUND OF THE INVENTION Conventionally, Japanese Examined Patent Publication (Kokoku) No. 2-23861 discloses a method of manufacturing an electrophotographic printing original plate which obtains a toner image by an electrophotographic method. This method is formed by a charging step of charging a printing original plate material obtained by coating a photoconductive layer on the surface of an aluminum support, an exposure step of exposing the charged printing original plate material, the charging and the exposing step. And a fixing step of thermally fixing the toner image formed by the developing step to develop the electrostatic latent image of the printing original plate material by using a toner developing solution. It is a manufacturing method, and is attracting attention as a technique capable of reducing the plate-making time and the plate-making cost.

The original plate obtained by this method has toner adhered and fixed to the image area on the photoconductive layer.
Then, after the steps of elution of the non-image area, rinsing and gumming, the plate is dried to complete the plate making. That is, the plate-making process is completed by removing the photoconductive layer in the non-image area (portion to which toner is not attached) of the plate with an eluent, rinsing, removing the gum solution, and drying.

Conventionally, in JP-A-58-150953, o-naphthoquinonediazide-5-sulfonic acid ester was used in a photosensitive composition of a photoconductive layer constituting a printing original plate material, and after the toner was developed, an ultraviolet ray was generated. A technique is disclosed in which stable exposure of a printing plate is improved by exposing it to light and then eluting it to make a plate.

However, when such a composition is used,
Stable reproducibility is insufficiently improved, especially fine line reproduction and shadow part reproduction are inadequate, and stains occur during printing, and when a fatigued eluent is used, it is extremely difficult to elute pigment residue. There is a drawback that becomes. When a photoconductive layer using o-naphthoquinonediazide-5-sulfonate is used, it is easily exposed to a white fluorescent lamp that is generally used in an exposure workshop, and unnecessary when exposed and developed under a white fluorescent lamp. There is a drawback that photosensitization occurs, that is, the safelight property is poor.

[0006]

Therefore, an object of the present invention is to improve stable reproducibility sufficiently, particularly excellent in fine line reproducibility and shadow part reproducibility. It is an object of the present invention to provide an electrophotographic printing original plate in which the pigment residue is reduced in elution even when used, and which is excellent in safelight property even when exposed under a white fluorescent lamp.

[0007]

The inventor of the present invention has reached the present invention as a result of extensive studies to achieve the above object.

In the electrophotographic printing original plate according to the present invention, a toner image is formed on a printing original plate material having a photoconductive layer provided on an aluminum support by an electrophotographic method, and a non-image portion is eluted to prepare a plate. In the electrophotographic printing original plate thus obtained, the composition of the photoconductive layer contains a photoconductive substance, an o-naphthoquinonediazide-4-sulfonic acid ester or amide compound, or a polymer compound.

A preferred embodiment of the present invention is characterized in that the aluminum support is grained and anodized.

[0010]

[Specific Structure of the Invention]

(Printing plate material) The printing plate material used in the present invention is basically formed by coating a photoconductive layer on an aluminum support.

The aluminum support is preferably first grained. This graining treatment mechanically roughens the surface and is called a so-called mechanical roughening method, and examples thereof include ball polishing, brush polishing, honing polishing, and a combination thereof. It is also possible to use a so-called electrolytic polishing surface roughening treatment for electrically roughening the surface. For example, electrolytically treating the support with an alternating current or a direct current in an electrolytic solution (bath) containing hydrochloric acid or nitric acid. You can also

Since smut may be formed on the surface of the support obtained by the graining treatment as described above, appropriate treatment such as washing with water or alkali etching may be performed to remove the smut. It can be done if necessary. As such a process, for example, Japanese Patent Publication No. 48-2
Treatment methods such as the alkali etching method described in Japanese Patent No. 8123 and the sulfuric acid desmutting method described in Japanese Patent Application Laid-Open No. 53-12739 are mentioned.

After the above-mentioned pretreatment, the aluminum support is preferably subjected to anodization to form an oxide film on the support in order to improve abrasion resistance, chemical resistance and water retention. .. In this anodic oxidation, generally, an aqueous solution containing sulfuric acid and / or phosphoric acid or the like at a concentration of 10 to 50%, preferably an aqueous solution containing sulfuric acid at a concentration of 10 to 50% is used as an electrolytic solution to obtain a current density of 1 to 10 A / dm ^2. The method of electrolysis in US Pat.
There is a method of electrolyzing in sulfuric acid at a high current density described in No. 8 and a method of electrolyzing using phosphoric acid described in US Pat. No. 3,511,661.

An aluminum support can be obtained as described above, and then a photoconductive layer is formed on this support.

The composition of the photoconductive layer is characterized by containing a photoconductive substance, an o-naphthoquinonediazide-4-sulfonic acid ester or amide compound (hereinafter referred to as the compound of the present invention), and a polymer compound.

As the photoconductive substance, for example, copper phthalocyanine or the like is used.

The compound of the present invention, o-naphthoquinonediazide-4-sulfonic acid ester, is a polycondensation resin of phenols and aldehydes or ketones, or a reaction product of phenols and o-naphthoquinonediazide-4-sulfonyl chloride. Partial ester compounds, or compounds obtained by crosslinking or modifying these partial ester compounds with polyfunctional or monofunctional isocyanates.

Examples of the phenols include monohydric phenols such as phenol, cresol, 3,5-xylenol and thymol, dihydric phenols such as catechol, resorcinol and hydroquinone, pyrogallol and phloroglucin.

Examples of the aldehyde include formaldehyde, benzaldehyde, acetaldehyde, crotonaldehyde, furfural and the like. Of these,
Preferred are formaldehyde and benzaldehyde.

Further, examples of the ketone include acetone and methyl ethyl ketone.

Specific examples of the polycondensation resin include phenol / formaldehyde resin, cresol / formaldehyde resin, pyrogallol / acetone resin and the like.

OH of phenols of the compounds of the present invention
The condensation rate of o-naphthoquinonediazide-4-sulfonic acid with respect to the group (reaction rate with respect to one OH group) is preferably 10 to 70%, more preferably 15 to 60%.

Next, the o-naphthoquinonediazide of the present invention
Examples of 4-sulfonic acid amide compounds include polycondensation resins of anilines, aminophenols and aldehydes or ketones, or reaction products of aminophenols, anilines and o-naphthoquinonediazide-4-sulfonyl chloride.

O-naphthoquinonediadi to the amino group
Condensation rate of do-4-sulfonic acid (NH₂Anti to one base
The response rate is preferably 10 to 70%, more preferably 15 to 60 %
Is.

The proportion of the compound of the present invention in the photoconductive layer composition (excluding the solvent) is preferably 1 to 50% by weight,
It is particularly preferably 5 to 40% by weight.

Next, a polymer compound other than the above is used in the photoconductive layer composition. As such a polymer compound, a group consisting of chlorinated polypropylene, cresol novolac resin, or hydroxyphenyl methacrylate is a constituent part. The methacrylic copolymer contained as is preferably used. The blending amount of the polymer compound is preferably 5 to 95% by weight, more preferably 5 to 80% by weight in the photoconductive layer composition (excluding the solvent). In the present invention, the photoconductive layer composition may further contain a filler, a dye, a dye, a pigment, a surfactant for improving coatability, and other conventional additives and auxiliaries.

The thickness of the photoconductive layer is preferably 0.1 ~100mg / dm ^2, more preferably 1 to 50 mg / dm ^2.

The printing plate material used in the present invention is formed by coating the above-mentioned aluminum support with the dispersion liquid of the photoconductive layer composition by a known coating method.

(Manufacturing method of electrophotographic printing original plate) In the present invention, the lithographic printing original plate is subjected to toner development by an electrophotographic method to obtain a toner image, and then elution of the photoconductive layer in the non-image area, rinsing, gumming, etc. It can be obtained by going through each step.

In the present invention, in order to obtain a toner image by toner development, after the photoconductive layer is charged by a usual corona charging method, reflection exposure using a xenon lamp, a halogen lamp, a tungsten lamp or a fluorescent lamp as a light source, Alternatively, a toner image can be obtained by performing toner development after exposure with a gas laser such as an argon laser or a helium neon laser or a semiconductor laser, or contact exposure through a transparent positive film. Further, after the exposure, the toner image can be obtained by charging and utilizing the photoconductive memory.

The developing method used in the present invention may be a dry method using a developer in which toner or carrier is solid, a wet method in which toner or carrier is liquid, or whether the toner or carrier is solid or liquid. Although there is an aerosol developing method using an air stream as a carrier, the liquid developing method is preferable in order to obtain an image with high resolution.

The toner used in the present invention is preferably hydrophobic and ink-receptive. For example, polystyrene resin, polyolefin resin, polyester resin (amino group-containing acrylic ester, long chain acrylic ester, etc.), acrylic resin ( Polymers such as resins having phenolic hydroxyl groups and sulfone groups), epoxy resins, vegetable oils, modified alkyd resins, cyclized rubbers, asphalt, vinyl chloride, etc. are included. Further, coloring agents such as carbon black, nigrosine pigments, phthalocyanine blue, phthalocyanine green, benzidine yellow and the like, and charge control agents such as fatty acid and metal salts of naphthenic acid, and the like are included within a range that does not adversely affect the granulation property and fixing property of the toner. It may contain metal dyes, sulfonates and the like.

Next, after the toner image is obtained as described above, the toner image is thermally fixed through steps such as rinsing and drying.

Next, the non-image area is eluted. To elute the non-image area, for example, a method of supplying a photoconductive layer removing liquid to the photoconductive layer is used.

In the present invention, various methods can be considered for supplying the photoconductive layer removing liquid.

As a preferable supply method, (1) as described in JP-A-58-25477, the photoconductive layer removing liquid is sprayed in a shower or spray form while the printing plate material is conveyed horizontally, and further removed. A method of circulating and supplying a liquid, (2) as described in JP-A-2-96773, while curving the printing plate material in a dipping tank in which a large amount of photoconductive layer removing liquid is stored Method of supplying photoconductive layer removing liquid, (3) JP-A-61-243455 and JP-A-61-2467
No. 50, No. 63-197950, etc., there may be mentioned a new liquid supply method for supplying an unused liquid to the plate surface by coating or the like.

Of these, the new liquid supply method is preferable because it is possible to avoid the effect of fatigue of the photoconductive layer removing liquid and keep the removability highly stable.

In the new liquid supply system, the photoconductive layer removing liquid is supplied to the photoconductive layer in a substantially unused state. The liquid in a substantially unused state includes not only a liquid that has not been used at all, but also a liquid that has been collected from the liquid supplied from the supply unit without reaching the plate surface. The supply amount of the photoconductive layer-removing liquid is suitably 70~700cc / m ² to the area of the photoconductive layer of interest, preferably 100~400cc / m ^2. When it is less than 70 cc / m ² , it is difficult to uniformly supply the liquid to the entire photoconductive layer, and when it is more than 700 cc / m ² , it is excessively supplied to the photoconductive layer. Is wasted.

After the photoconductive layer removing liquid is applied, an elution treatment is performed to remove the photoconductive layer in the non-image area where the toner image is not formed. In this elution step, the photoconductive layer is washed out by means of a shower, roller, brush or the like. The elution treatment may be carried out with the photoconductive layer removing liquid still applied, but a liquid having a lower solubility / removability for the photoconductive layer than the photoconductive layer removing liquid, such as water, a surfactant or an alkali. It is preferable to perform the treatment in a state where the water mixed with the solution is applied, from the viewpoint of preventing the image from being scratched.

When the photoconductive layer contains a pigment such as a coloring pigment or a photoconductive pigment, it is indispensable to perform physical rubbing by a rubbing member which is pressed against a recording material such as a sponge roller or a brush. is there.

As the photoconductive layer removing liquid used in the present invention, a solution prepared by dissolving an inorganic and / or organic basic substance in water and / or an organic solvent can be used.

Examples of the inorganic basic substance include alkali metal and alkaline earth metal hydroxides such as ammonium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, strontium hydroxide, and phosphoric acid alkali salts, for example. Examples thereof include sodium phosphate, potassium phosphate, and alkali silicate salts such as sodium silicate and potassium silicate.

Examples of the organic basic substance include trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, butylamine, isobutylamine, dibutylamine, tributylamine, diisobutylamine, octylamine and dioctylamine. Primary or tertiary lower saturated amine, further piperidine, N-methylpiperidine, N-ethylpiperidine, morpholine, or amyl alcohol such as ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, Alternatively, diamines and polyamines such as ethylenediamine, diethylenetriamine and triethylenetetramine, and lower-substituted amides such as dimethylformamide are listed. It is.

Water and / or an organic solvent is used as a solvent for dissolving and diluting these basic substances. As the organic solvent, dibutyl ether, ethyl butyl ether, diisopropyl ether, dioxane, ethers such as tetrahydrofuran, acetone, methyl ethyl ketone, lower ketones such as diisopropyl ketone, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, Lower esters such as methyl butyrate and ethyl butyrate and methanol, ethanol, propanol, isopropanol, isobutanol, benzyl alcohol,
Examples thereof include those containing an alcohol group such as ethylene glycol, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and phenyl cellosolve.

Further, it is also preferable to add various surfactants to the photoconductive layer removing liquid in order to promote the penetration of the photoconductive layer removing liquid into the photoconductive layer or to improve the wettability to the photoconductive layer surface. The preferable surfactant can be appropriately selected from anionic surfactants, nonionic surfactants, and cationic surfactants.

[0046]

EXAMPLES Next, the present invention will be described more specifically with reference to examples of the present invention.

Example 1 Production of printing plate material 1 An aluminum plate (JIS 1100) having a thickness of 0.30 mm was degreased with an aqueous solution of caustic soda, and then in a 0.3 mol / liter hydrochloric acid aqueous solution (30 ° C.), a current density of 50 A / Electrolytic polishing surface roughening treatment was performed for 30 seconds by alternating current of dm ² . Next, desmut treatment is performed in a 5% caustic soda aqueous solution at 60 ° C for 10 seconds, and further in a 20% sulfuric acid solution at 20 ° C at a current density of 3 A / dm.
^The sample was anodized at ² for 1 minute and washed with water. After the treatment, it was immersed in hot water (80 ° C.) for 30 seconds and dried with warm air to obtain an aluminum support for a printing original plate material.

Subsequently, a photoconductive layer-forming dispersion liquid-1 (viscosity 3000 cps) having the following composition was dispersed with a sand grinder for 3 hours, then applied with a wire bar and dried at 90 ° C. for 10 minutes, A printing original material 1 was obtained. The film thickness of the applied photoconductive layer was 50 mg / dm ² .

<Dispersion liquid-1 for forming photoconductive layer> ε-type copper phthalocyanine (“Liophoton-EK” manufactured by Toyo Ink Co., Ltd.) 10 parts by weight 33% o-naphthoquinonediazide of p-cresol novolak resin (Mw2000) 4-Sulfonic acid ester compound 3 parts by weight Phenol, m-cresol, p-cresol formalin novolac resin (mixing ratio = 30:42:28 (weight ratio)) 30 parts by weight Propylene glycol monomethyl ether 80 parts by weight

Next, using printing plate material 1,
As described in JP-A-23861, toner development is performed by charging, exposure, toner development, rinsing, drying, fixing, and cooling to obtain a toner image, and then UV exposure is performed under the following exposure conditions, followed by non-image formation. The line portion was eluted, and rinsed and gummed.

[Exposure Conditions] Lamp: Metal halide lamp 4 kw (manufactured by Dainippon Screen Co., Ltd.) Exposure time: 20 seconds (distance 1.5 m) The toner developer and non-image area eluent used here are as follows. is there.

<Liquid Toner Developer> A solution prepared by dispersing the following mixed solution with a sand grinder and further diluted with Isopar G to a solid content concentration of 1.0% by weight.

Carbon black (MA-100 manufactured by Mitsubishi Kasei Co., Ltd.) 10 parts by weight Ethylene vinyl acetate copolymer (DQ, DJ-7197 manufactured by Nippon Unicar Co., Ltd.) 1 part by weight Stearyl methacrylate / methacrylic acid copolymer (charged mol) Ratio = 8: 2) Weight average molecular weight about 100,000 parts by weight Polyethylene (Sun wax 171P manufactured by Sanyo Kasei Co., Ltd.) 15 parts by weight Isopar G (manufactured by Exxon) 200 parts by weight

<Non-image area eluate-1> (aqueous solution below) benzyl alcohol 1 wt% propylene glycol 1 wt% triethanolamine 1 wt% p-butylbenzoic acid 1 wt% A potassium silicate 6 wt% 50% KOH 6 wt% Perex NBL (Manufactured by Kao Corporation) 0.05 wt% EDTA.4Na 0.01 wt%

<Evaluation> Using the obtained plate, stable reproducibility, stain resistance, elution, and safelight property were evaluated as follows.

[0056]Stable reproducibility Run the liquid toner for 1 week without changing the toner developer and eluate.
(20 plates per day (400 mm x 500 mm Rhino
D)), and the reproducibility of a fine line of 50μ was measured on the plate. rose
The width of the tsukitsuki is shown in Table 1.

The smaller the stable reproducibility value in Table 1, the better.

Staining property The obtained plate was printed on a printing machine under the following conditions to print 50,000 sheets, and the stains on the printed matter were visually observed.

[Printing conditions] Printing machine DAIYA1F (manufactured by Mitsubishi Heavy Industries, Ltd.) Ink TOOKING MARKV (manufactured by Toyo Ink Co., Ltd.) Paper Coated paper fountain solution TOTAL N-1 (manufactured by Toka Dye Co., Ltd.) Isopropanol 5 wt% Volume of dampening water 60

[Evaluation Criteria] ◎: No stain at all ○: No stain Δ: Slightly stain ×: Stain

Using the new eluent solution and the exhausted eluent, the plate after elution was examined for the presence of residual pigment.

[Evaluation Criteria] ◯: No pigment residue is left Δ: Pigment residue is slightly left ×: Pigment residue is left

The safelight printing original plate material was left under a fluorescent lamp (40 W) at 2 m for 10 minutes, and thereafter, plate making and printing were carried out in the same manner. I observed small dots flying.

[Evaluation Criteria] ◯: Reproduction of small dots is good Δ: Reproduction of small dots is slightly poor ×: Reproduction of small dots is poor The above results are shown in Table 1.

Example 2 A printing original plate material 2 was obtained in the same manner as in Example 1 except that the photoconductive layer-forming dispersion liquid-1 was replaced with the following photoconductive layer-forming dispersion liquid-2. <Dispersion liquid-2 for forming photoconductive layer> ε-type copper phthalocyanine (“Liophoton-EK” manufactured by Toyo Ink Co., Ltd.) 10 parts by weight Reaction of p-methoxyaniline with o-naphthoquinonediazide-4-sulfonyl chloride 3 parts by weight Phenol, m-cresol, p-cresol formalin novolac resin (mixing ratio = 30:42:28 (weight ratio)) 30 parts by weight Propylene glycol monomethyl ether 80 parts by weight

Using the above printing plate material 2, plate making and evaluation were carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 3 A printing original plate material 3 was obtained in the same manner as in Example 1 except that the photoconductive layer-forming dispersion liquid-1 was replaced with the following photoconductive layer-forming dispersion liquid-3.

<Dispersion liquid-3 for forming photoconductive layer> ε-type copper phthalocyanine (“Liophoton-EK” manufactured by Toyo Ink Co., Ltd.) 10 parts by weight Pyrogallol, 20% o-naphthoquinone diamide of acetone resin (Mw2000) -4 -Sulfonic acid ester compound 3 parts by weight Phenol, m-cresol, p-cresol formalin novolac resin (mixing ratio = 30:42:28 (weight ratio)) 30 parts by weight Propylene glycol monomethyl ether 80 parts by weight

Using the above printing plate material 3, plate making and evaluation were carried out in the same manner as in Example 1. The results are shown in Table 1.

Examples 4 to 7 In Example 3, the addition amount of 20% o-naphthoquinonediamide-4-sulfonic acid ester compound of pyrogallol and acetone resin (Mw2000) in the dispersion liquid-3 for forming a photoconductive layer was as follows. Printing original materials 4 to 7 in the same manner except that
Got

Example 4 Addition amount 0.3 parts by weight Example 5 Addition amount 0.6 parts by weight Example 6 Addition amount 35 parts by weight Example 7 Addition amount 43 parts by weight

Using the above printing plate materials 4 to 7, a plate was prepared and evaluated in the same manner as in Example 3. The results are shown in Table 1.

Example 8 In Example 3, 20% o-naphthoquinone diamide-4-sulfonic acid ester compound of pyrogallol and acetone resin (Mw2000) in the photoconductive layer forming dispersion liquid-3 was added to pyrogallol and acetone resin (Mw2000). A printing original plate material 8 was obtained in the same manner except that the 15% o-naphthoquinone diamide-4-sulfonic acid ester compound of 4) was replaced.

Using the above printing plate material 8, plate making and evaluation were carried out in the same manner as in Example 3. The results are shown in Table 1.

Example 9 In Example 1, p-in the dispersion liquid-1 for forming a photoconductive layer was used.
33% o-naphthoquinonediazide-4-sulfonic acid ester compound of cresol novolac resin (Mw2000) was added as p.
A printing original plate material 9 was obtained in the same manner except that a 50% o-naphthoquinonediazide-4-sulfonic acid ester compound of cresol novolac resin (Mw2000) was used.

Using the above printing plate material 9, plate making and evaluation were carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 A comparative printing original plate material 1 was obtained in the same manner as in Example 1 except that the photoconductive layer forming dispersion liquid-1 was replaced with the following comparative photoconductive layer forming dispersion liquid-1. ..

<Comparative Dispersion Liquid for Photoconductive Layer-1> ε-type copper phthalocyanine (“Liophoton-EK” manufactured by Toyo Ink Co., Ltd.) 10 parts by weight 33% o-naphtho of p-cresol novolak resin (Mw2000) Quinonediazide-5-sulfonic acid ester compound 3 parts by weight Phenol, m-cresol, p-cresol formalin novolak resin (mixing ratio = 30:42:28 (weight ratio)) 30 parts by weight Propylene glycol monomethyl ether 80 parts by weight

Using the comparative printing plate material 1 described above, a plate was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 2 A comparative printing original plate material 2 was obtained in the same manner as in Example 1 except that the photoconductive layer-forming dispersion liquid-1 was replaced with the following comparative photoconductive layer-forming dispersion liquid-2.

<Dispersion liquid for forming photoconductive layer for comparison-2> ε-type copper phthalocyanine (“Liophoton-EK” manufactured by Toyo Ink Co., Ltd.) 10 parts by weight Phenol, m-cresol, p-cresol formalin novolac resin (prepared) Mixing ratio = 30: 42: 28 (weight ratio)) 33 parts by weight Propylene glycol monomethyl ether 80 parts by weight Using the comparative printing plate material 2 above, a plate was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0081]

[Table 1]

[0082]

According to the present invention, stable reproducibility is sufficiently improved, particularly fine line reproduction and shadow part reproducibility are excellent, stains are not removed during printing, and elution is performed even when a fatigued eluate is used. It is possible to provide an electrophotographic printing original plate which has a reduced residual pigment, has a wide handling latitude under a white fluorescent lamp, and is excellent in safelight property.

Claims (2)

[Claims] 1. An electrophotographic printing original plate obtained by forming a toner image on a printing original plate material having a photoconductive layer provided on an aluminum support by an electrophotographic method and eluting a non-image area to make a plate. Wherein the composition of the photoconductive layer is a photoconductive material, o-naphthoquinonediazide-4-
An electrophotographic printing original plate comprising a sulfonic acid ester or amide compound and a polymer compound. 2. The electrophotographic printing original plate according to claim 1, wherein the aluminum support is grained and anodized.