JPH0362263B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plate-making method for producing a lithographic printing plate from a photosensitive lithographic printing plate, and particularly relates to a plate-making method in which a washing step after development is omitted. JP-A No. 54-8002 discloses that after a photosensitive lithographic printing plate (called a Pre-Sensitized Plate, abbreviated as a PS plate) is exposed and developed,
A plate-making method is disclosed in which gumming is performed immediately without a water-washing step. This plate-making method is advantageous in terms of waste liquid treatment because it omits the water washing process, but it not only consumes the desensitizing agent used for gumming significantly, but also requires development ink filling and correction processing. This is a disadvantageous plate-making method in some cases. As a plate-making method that eliminates these drawbacks, US Pat. No. 4,291,117 discloses a plate-making method in which a PS plate is imagewise exposed and developed, and then treated with an aqueous solution containing a surfactant. This plate-making method also omits the washing step, which is advantageous in terms of waste water and waste liquid treatment measures. However, when so-called gumming is applied to the lithographic printing plate obtained by platemaking in this manner for the purpose of protecting the image area and improving the insensitivity of the non-image area, the non-image It has been found that this method tends to be inferior in its ability to increase the hydrophilicity of a region when compared to conventional methods, and has the problem that the desired effect of gumming is not fully exerted. Accordingly, an object of the present invention is to provide a plate-making method that can efficiently gum an SP plate after imagewise exposure and development without a washing process. Another object of the present invention is to provide an improved plate-making method that does not cause pollution due to washing water. Still another object of the present invention is a plate-making method that can efficiently perform correction processing such as erasing unnecessary image portions and additions on a lithographic printing plate without going through a water washing process after image exposure and development of a PS plate. The goal is to provide the following. As a result of extensive research to achieve the above object, the present inventors discovered that after imagewise exposure and development of a PS plate, polymerized phosphoric acid, its alkali metal salt and organic phosphonic acid were added to an aqueous solution mainly composed of an anionic surfactant. By treating with an aqueous solution containing at least one compound selected from the group consisting of alkali metal salts of It has been found that the desired desensitization by gumming can be achieved satisfactorily. That is, the present invention is a plate-making method characterized in that after a PS plate is imagewise exposed and developed, it is immediately treated with an aqueous solution containing an anionic surfactant and a polymerized alkali metal phosphate or an organic phosphonic acid without washing with water. be. The above-mentioned anionic surfactants that can be used in the present invention include those having various structures. For example, fatty acid salts, alkyl sulfonate salts, alkylbenzene sulfonate salts, alkylnaphthalene sulfonate salts, dialkyl sulfosuccinate salts, alkyl phosphate salts, naphthalene sulfonate formalin condensates, polyoxyethylene alkyl sulfonate salts, Examples include alkyl diphenyl ether disulfonate salts. The above anionic surfactants may be used alone or in combination of two or more, and are contained in the aqueous solution in an amount of about 0.1% to about 20% by weight, more preferably 0.5% to 10% by weight. On the other hand, at least one compound selected from the group consisting of polymerized phosphoric acid, its alkali metal salt, organic phosphonic acid, and its alkali metal salt, which is a component used in combination with the anionic surfactant, is a component used in the non-image area of the lithographic printing plate. It has the effect of improving the hydrophilicity of. Specific examples of polymerized phosphoric acid and its alkali metal salts include tripolyphosphoric acid, pyrophosphoric acid, tetraphosphoric acid, hexametaphosphoric acid, and their sodium and potassium salts, among which hexametaphosphoric acid and its sodium and potassium salts. is particularly preferred. In addition, organic phosphonic acids and their alkali metal salts include aromatic,
Includes heterocyclic, aliphatic and cycloaliphatic small molecules, and high molecular weight phosphonic acids and derivatives thereof, as described in US Pat. Nos. 3,404,003 and 4,349,391. For example, 2-phosphono-
Ethane-1-sulfonic acid, 3,3-diphosphono-pimelic acid, vinylphosphonic acid monomethyl ester, 4-chlorophenylphosphonic acid, 4-chloro-3-nitro-phenylphosphonic acid, β-styrylphosphonic acid, 2-phosphonic acid butanetricarboxylic acid 1,2,4,1-phosphonoethanetricarboxylic acid-1,2,3,1-hydroxyethane-1,
Examples include 1-diphosphonic acid, aminotrimethylenephosphonic acid, polyvinylphosphonic acid, etc. Among them, 1-phosphonoethanetricarboxylic acid-
1,2,3,1-hydroxyethane-1,1-diphosphonic acid and polyvinylphosphonic acid are particularly preferred. These compounds can be used alone or in combination of two or more and can be used effectively in a wide range of concentrations, but the optimum concentration is determined depending on the compound used. A more specific concentration guide is approximately 0.01
~30% by weight, particularly in the case of polymerized phosphoric acids and their alkali metal salts, 0.01 to 15% by weight, more preferably 0.03 to 10% by weight, and 0.1 in the case of organic phosphonic acids and their alkali metal salts. weight%
~30% by weight, more preferably 0.05~
It is 20% by weight. The processing liquid used after development in the plate-making method of the present invention is basically composed of the above-mentioned components, and its effect is fully exhibited especially when the pH value is in the range of 2 to 11. If the developer is alkaline, the ability to neutralize the developer remaining on the developed PS plate or the pH of the remaining developer
In order for the aqueous solution of the above composition to also have the ability to reduce
It is adjusted to be 5. Such a PH value can be achieved by further containing an acidic substance or buffer. Preferred compounds that can be used in such acids and buffers include acids such as acetic acid, oxalic acid, tartaric acid, benzoic acid, molybutenic acid, boric acid, nitric acid, sulfuric acid, phosphoric acid and polyphosphoric acid, as well as water-soluble alkalis thereof. Metal salts and ammonium salts, such as ammonium acetate, sodium acetate, potassium acetate, sodium molybutate, potassium molybutate, sodium borate, ammonium borate, lithium nitrate, sodium nitrate, potassium nitrate, monosodium phosphate, dibasic sodium phosphate, tertiary Sodium phosphate, monopotassium phosphate, dibasic potassium phosphate, tribasic potassium phosphate, tribasic ammonium phosphate,
Contains sodium polyphosphate. For details on buffering agents, see, for example, "Chemical Handbook Basic Edition" revised 2nd edition, written by the Chemical Society of Japan, published by Maruzen Co., Ltd., Nos. 1490-1499.
These can be directly applied to the present invention. It is more preferable that the aqueous solution comprising the above-mentioned components also contains a lipophilic substance. As a result, the image area of the lithographic printing plate becomes more oil-sensitive, and development ink can be applied even more efficiently. The decline can be significantly suppressed. Preferred lipophilic substances include organic carboxylic acids having from 5 to 25 carbon atoms, such as oleic acid, lauric acid, valeric acid, nonylic acid, capric acid, mystilic acid, palmitic acid, castor oil, and the like. These lipophilic substances can be used alone or in combination of two or more, and in the aqueous solution containing the anionic surfactant of the present invention, from about 0.005% to about 10% by weight based on the total weight, More preferably
It is contained in a range of 0.05 to 5% by weight. Work efficiency can be improved by including a small amount of antifoaming agent for the purpose of reducing foaming caused by the anionic surfactant. As a preferable antifoaming agent, a silicone-based antifoaming agent is preferable because it is effective even in a small amount. The above-mentioned aqueous solution is effective against planographic printing plates obtained by image exposure and development from various PS plates.
It can be advantageously used as a processing agent when processing without washing with water. Preferred PS plates include a photosensitive layer made of a mixture of diazo resin (salt of a condensate of p-diazodiphenylamine and paraformaldehyde) and silica, as described in British Patent No. 1350521, for example. Mounted on a board, British Patent No. 1460978;
1505739, a negative PS plate and a photosensitive layer made of a mixture of a diazo resin and a polymer containing a hydroxyethyl methacrylate unit or a hydroxyethyl acrylate unit as a main repeating unit on an aluminum plate; This includes positive-working PS plates in which a photosensitive layer made of an o-quinonediazide compound is provided on an aluminum plate.
This embodiment is particularly effective in the plate-making method of producing a lithographic printing plate from a PS plate, so this embodiment will be described in detail below. The positive PS plate used in a preferred embodiment of the plate making method of the present invention is one in which a photosensitive layer made of an o-quinonediazide compound, more preferably an o-naphthoquinonediazide compound, is provided on a support. Suitable supports include metal plates such as aluminum (including aluminum alloys), zinc, copper, etc., such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate. , polyethylene, polypropylene, polyethylene, polycarbonate, polyvinyl acetal, etc., and metal laminated or vapor-deposited as described above. Among these, aluminum plates are particularly dimensionally stable and are particularly preferred supports. In the case of a support, especially a support having an aluminum surface, surface treatments such as graining treatment, immersion treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, etc., and anodization treatment are performed. Preferably. Also, as described in U.S. Patent No. 2,714,066, an aluminum plate is grained and then immersed in an aqueous sodium silicate solution, and an aluminum plate is anodized as described in U.S. Pat. No. 3,181,461. After that, a material obtained by immersion treatment in an aqueous solution of an alkali metal silicate is also suitably used. The above anodic oxidation treatment can be performed using, for example, phosphoric acid, chromic acid, sulfuric acid,
It is carried out by passing an electric current through an aluminum plate as an anode in an electrolytic solution consisting of an aqueous solution or a non-aqueous solution of an inorganic acid such as boric acid, an organic acid such as oxalic acid or sulfamic acid, or a salt thereof, or a combination of two or more thereof. Ru. Also effective is silicate electrodeposition as described in US Pat. No. 3,658,662. Furthermore, Japanese Patent Publication No. 1974-27481, Japanese Patent Application Publication No. 1973-
Also useful are supports coated with electrolytic grains and subjected to the above-mentioned anodic oxidation treatment, as disclosed in Japanese Patent Laid-Open No. 58602 and Japanese Patent Application Laid-Open No. 52-30503. These hydrophilic treatments are performed not only to make the surface of the support hydrophilic, but also to prevent harmful reactions with the photosensitive composition provided thereon, and to improve the adhesion with the photosensitive layer. It is applied for various purposes, such as to improve the quality of life. The photosensitive layer provided on the hydrophilic surface of the support consists of an o-naphthoquinone diazide compound. Such o-naphthoquinone diazide compounds are described, for example, in U.S. Pat. No. 3,046,110, U.S. Pat.
No. 3046121, No. 3046115, No. 3046118, No. 3046119, No. 3046120, No. 3046121,
Same No. 3046122, Same No. 3046123, Same No. 3061430,
Same No. 3102809, Same No. 3106465, Same No. 3635709,
It is described in numerous publications, including the specifications of the same No. 3647443, and these can be suitably used. Among these, o-naphthoquinone diazide sulfonic acid esters or o-naphthoquinone diazide carboxylic acid esters of aromatic hydroxy compounds, and o-naphthoquinone diazide carboxylic acid esters of aromatic amino compounds are particularly useful.
naphthoquinonediazide sulfonic acid amide or o
-Naphthoquinone azidocarboxylic acid amides are preferred, particularly those prepared by esterifying o-naphthoquinonediazide sulfonic acid with the condensate of pyrogallol and acetone described in U.S. Pat. No. 3,635,709, and U.S. Pat. No. 4,028,111 O-naphthoquinone azidosulfonic acid, or o-naphthoquinone azidosulfonic acid, or
- Ester-reacted naphthoquinonediazidecarboxylic acids, homopolymers of p-hydroxystyrene as described in British Patent No. 1494043, or copolymers of this with other copolymerizable monomers. - Ester-reacted naphthoquinonediazide sulfonic acid or o-naphthoquinonediazidecarboxylic acid, U.S. Patent No. 3759711
In the copolymer of p-aminostyrene and other copolymerizable monomers as described in the specification of
-Naphthoquinonediazide sulfonic acid or o-naphthoquinonediazidecarboxylic acid subjected to amide reaction is very good. These o-naphthoquinone diazide compounds are
Although it can be used alone, it is preferable to mix it with an alkali-soluble resin and provide this mixture as a photosensitive layer. Suitable alkali-soluble resins include:
Novolak type phenolic resins are included, and specifically, phenol formaldehyde resins, o-cresol formaldehyde resins, m-cresol formaldehyde resins, etc. are included. Furthermore, Tokukai Akira
As described in Publication No. 50-125806, in addition to the above-mentioned phenol resin, a condensation product of phenol or cresol substituted with an alkyl group having 3 to 8 carbon atoms, such as t-butylphenol formaldehyde resin, and formaldehyde. It is even more preferable to use these together. Alkali soluble resin is
About 50 to about 85% by weight in the photosensitive layer, more preferably 60 to about 85% by weight
Contains 80% by weight. Additives such as dyes, plasticizers, and components imparting printout performance can be added to the photosensitive layer made of the o-naphthoquinone diazide compound, if necessary. Dyes are used to provide contrast between the image area and the non-image area (support surface) after exposure and development of the PS plate; for example, C.
I.26105 (oil red RR), CI21260 (oil scarlet #308), CI74350 (oil blue),
Alcohol soluble dyes such as CI52015 (methylene blue) CI42555 (crystal violet) are preferred. Such dyes need only be added in an amount sufficient to provide a clear contrast between the color of the hydrophilic surface of the support exposed by exposure and development of the photosensitive printing plate and the remaining portion of the photosensitive layer. Specifically, it is suitable that the content is about 7% by weight or less based on the total amount of the photosensitive composition. Plasticizers are effective for making the photosensitive layer provided on the support have desired flexibility, and include, for example, dimethyl phthalate, diethyl phthalate,
Dibutyl phthalate, diisobutyl phthalate,
Phthalate esters such as dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butylbenzyl phthalate, diisodecyl phthalate, diaryl phthalate, dimethyl glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl Glycol esters such as phthalyl butyl glycolate and triethylene glycol dicaprylate, phosphate esters such as tricresyl phosphate and triphenyl phosphate, diisobutyl adipate, dioctyl adipate,
Aliphatic dibasic acid esters such as dimethyl sebacate, dibutyl sebacate, dioctyl azelate, and dibutyl maleate, polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate, and the like are effective. The plasticizer is contained in an amount of about 5% by weight or less based on the total amount of the photosensitive composition. The printout material is used so that a visible image can be immediately observed by imagewise exposing the photosensitive layer of the PS plate. For example, British patent no.
PH indicator as described in specification No. 1041463,
Examples include a combination of o-naphthoquinonediazide-4-sulfonyl chloride and a dye as described in US Pat. No. 3,969,118, and a photochromic compound as described in Japanese Patent Publication No. 44-6413. Furthermore, as described in JP-A-52-80022, the sensitivity can be increased by adding a cyclic acid anhydride to the photosensitive layer. A photosensitive composition comprising such o-naphthoquinone diazide is coated onto a support from a solution in a suitable solvent. Suitable solvents include glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and 2-methoxyethyl acetate, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and chlorinated hydrocarbons such as ethylene dichloride. . The coating amount of the photosensitive layer made of an o-naphthoquinonediazide compound provided on the support is about 0.5 to about 7
g/m ² , more preferably 1.5 to 3 g/m ² . When the positive PS plate thus obtained is exposed through a transparent original to a light beam rich in actinic light such as a carbon arc lamp, mercury lamp, metal halide lamp, xenon lamp, or tungsten lamp,
That part becomes alkali-soluble. Therefore, the exposed portion of the photosensitive layer is eluted by the alkaline aqueous solution, and the hydrophilic surface of the support is exposed. The developer used in the present invention is an alkaline aqueous solution containing dissolved silicate. Preferred silicates are those that exhibit alkalinity when dissolved in water;
Examples include alkali metal silicates such as sodium silicate, potassium silicate, and sodium metasilicate, and ammonium silicate. The amount of silicate in the developer solution is generally about 1% based on the total weight of the developer solution.
~10% by weight, more preferably 1-8%, most preferably 2-6%. The developer used in the present invention may be alkaline, preferably having a pH of about 10.5 to about 13.5 at 25°C.
It is. As the pH becomes lower than 10.5, the elution of the exposed photosensitive layer of the positive PS plate becomes insufficient. On the other hand, as the pH becomes higher than 13.5,
The amount of acid required in the aqueous solution containing the surfactant is increased. Therefore, the most preferable pH is 12 to 13.5. The developer used in the present invention may further contain an organic solvent in an amount of 5% by weight or less based on the total weight. Examples of such organic solvents include benzyl alcohol, 2-butoxyethanol, triethanolamine, diethanolamine, monoethanolamine, glycerin, ethylene glycol, polyethylene glycol, and polypropylene glycol. The developer used in the present invention can further contain a surfactant. This allows the developer to wet the surface of the photosensitive layer of the PS plate well.
The throughput of the developer (the amount of photosensitive layer that can be dissolved and removed by a unit volume of the developer) can be improved, and the range of development conditions (temperature, processing time, etc.) that provide optimal results can be expanded. Preferred such surfactants include anionic surfactants and amphoteric surfactants. Preferred specific examples of anionic surfactants include alkylbenzenesulfonic acid salts such as sodium dodecylbenzenesulfonate (the alkyl group has 8 to 18 carbon atoms, more preferably 12 to 16 carbon atoms), for example,
Alkylnaphthalene sulfonates such as sodium isopropylnaphthalene sulfonate (the alkyl group has 3 to 10 carbon atoms), formalin condensates of naphthalene sulfonates, dialkyl sulfosuccinates (the alkyl group has 2 to 10 carbon atoms), 18),
These include dialkylamide sulfonate salts (the alkyl group has 11 to 17 carbon atoms), and the like. Preferred specific examples of amphoteric surfactants include imidazoline derivatives such as N-alkyl-N,N,N-tris(carboxymethyl)ammonium (the alkyl group has 12 to 18 carbon atoms), N-alkyl-N- Included are betaine-type compounds such as carboxymethyl-N,N-dihydroxyethylammonium (the number of alkyl groups is 12 to 18). The amount of such surfactant used is not particularly limited, but is generally about 0.003
~3% by weight, more preferably 0.006-1% by weight
It is contained in the developer at a concentration of . The developer used in the present invention can further contain an antifoaming agent. Suitable defoamers include:
There are compounds described in specifications such as US Pat. No. 3,250,727 and US Pat. Among these, organic silane compounds are preferred. It is desirable that the developer used in the present invention has good wettability to the surface of the photosensitive layer of the PS plate. In particular, it is preferable that the contact angle of the developer to the surface of the photosensitive layer of the PS plate is 85° or less, more preferably 60° or less, as measured by the air drop method. If the present invention is carried out using a developer with a contact angle greater than 85°, the ink tends to adhere unevenly to the image area of the lithographic printing plate where printing ink should be applied uniformly. Therefore, it is difficult to obtain good printed matter from such a lithographic printing plate. In order to obtain a developer having a low contact angle with the surface of the photosensitive layer of the PS plate, it can be achieved by incorporating the above-mentioned surfactant into the developer. Various conventionally known methods can be used to develop the image-exposed PS plate with the developer described above. Specifically, methods include immersing an image-exposed PS plate in a developer, spraying the developer from multiple nozzles onto the photosensitive layer of the PS plate, and using a sponge moistened with the developer to remove the PS plate. Examples include a method of wiping the photosensitive layer of the plate, and a method of applying a developer to the surface of the photosensitive layer of the PS plate using a roller. Furthermore, after the developer has been applied to the photosensitive layer of the PS plate in this manner, the surface of the photosensitive layer can be lightly rubbed with a brush or the like. Development conditions can be appropriately determined by those skilled in the art depending on the above-mentioned development method. For example, in the immersion development method, the material is immersed in a developer solution at about 15 to 35° C. for about 20 to 80 seconds. The lithographic printing plate obtained by imagewise exposing and developing the PS plate as described above is squeezed.
It is preferable to reduce the amount of developer on the printing plate. In the present invention, the amount of developer remaining on the surface of the lithographic printing plate after being squeezed is
It is preferably 10 ml/m ² or less, and this amount is preferably as small as possible. Therefore, the residual amount of the developer is more preferably 5 ml/m ² or less, and most preferably 3 ml/m ² or less. If the volume after being squeezed is more than 10 ml/ ^m2 , the surfactant-containing aqueous solution described earlier will deteriorate faster, especially if a large amount of PS plate is prepared with a certain amount of the same surfactant aqueous solution. In the case of processing, the processing capacity deteriorates quickly. A method for squeezing the plate surface of a planographic printing plate is, for example, a method in which the plate is passed between a pair of elastic rollers whose surfaces are coated with an elastic member such as rubber, and the developer on the plate surface is removed by the nip pressure. Alternatively, a method can be adopted in which an elastic plastic material with a smooth surface is placed along the transport path of the lithographic printing plate and brought into sliding contact with the plate surface to scrape off the developer from the plate surface. The lithographic printing plate thus developed is treated with an aqueous solution containing the surfactant of the present invention without being washed with water. Specific processing methods include pouring an appropriate amount of the above aqueous solution onto the plate surface and rubbing it with a sponge to coat the entire plate surface, immersing the plate in a container filled with the above aqueous solution, and applying the above aqueous solution with a roller. , a method of spraying the above aqueous solution onto the printing plate, etc. can be used. The lithographic printing plate obtained by processing in this way can be subjected to various processes such as development ink application, correction such as addition or erasure, and gumming, and any of these processes can be performed by It can be done effectively without any problems. Conventionally, after image exposure and development of the PS plate,
A plate-making method has been known in which the washing step after development is omitted by gumming immediately without washing with water. However, the disadvantage of lower performance compared to the conventional method could not be avoided. Furthermore, after development, it is practically impossible to apply development ink or make corrections on a lithographic printing plate that has not been washed with water. However, even if the lithographic printing plate obtained by the plate-making method according to the present invention is immediately gummed, the processing ability of the plate surface protective agent is hardly reduced. Moreover, applying development ink and making corrections to the planographic printing plate obtained by the plate-making method of the present invention is almost as easy as performing these treatments on a planographic printing plate that has been sufficiently washed with water after development. can be done. Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that "%" indicates weight %. Examples 1 to 8 and Comparative Examples 1 to 2 Grained 2S aluminum plates were immersed in a 2% aqueous sodium hydroxide solution kept at 40° C. for 1 minute to partially corrode the surface. After washing with water, it was immersed in a sulfuric acid-chromic acid mixture for about 1 minute to expose the surface of pure aluminum. This was immersed in 20% sulfuric acid kept at 30°C, anodized for 2 minutes at a DC voltage of 1.5 volts and a current density of 2 amperes/dm ² , then washed with water and dried. A photosensitive solution having the composition shown below was coated onto the aluminum plate thus treated so that the dry weight was 2 g/m ² and dried to obtain a PS plate. Acetone - naphthoquinone of pyrogallol resin -
1,2-diazide(2)-5-sulfonic acid ester (synthesized by the method described in Example 1 of US Pat. No. 3,635,709)...5g tert-butylphenol-formaldehyde resin...0.5g Cresol-formaldehyde resin...5 g Methyl ethyl ketone...50 g Cyclohexanone...40 g This PS plate was exposed to light for 30 seconds from a distance of 1 m using a 3 kW metal halide lamp through a transparent positive film in a vacuum printing frame. This was developed using a developer (25°C) having the following composition. JIS No. 3 Sodium silicate…10g Potassium hydroxide…7g Sodium isopropylnaphthalene sulfonate
…20g Benzyl alcohol …30g Add water to make 1000ml. After removing the developing solution adhering to the surface of the developed PS plate using a squeegee, the plate was treated with a processing solution having the composition shown in Table 1 below.

[Table] Also, as Comparative Example 2, the developed PS plate was washed with water and dried. Divide each plate into two equal parts and use commercially available gum liquid on one side.
I pulled gum. Each plate-made printing plate was placed indoors (20 to 25
℃) for 3 days, then print according to the normal procedure, and the number of prints from the start of printing to the time when a sufficient printing ink density is obtained (hereinafter referred to as the number of printed sheets).
and stains in non-image areas of the printed matter were examined. For the remaining people, remove the dampening water roll of the printing press and apply ink to the entire surface of the plate, then run the dampening water system normally to remove the ink adhering to non-image areas and produce normal printed matter. The number of sheets obtained (hereinafter referred to as the number of inked sheets) was investigated, and the results are shown in Table 2.

[Table] △Slightly poor, ○Good, ◎Very good From the results in Table 2, the plate-making method according to the present invention has lower ink receptivity and stains than when washing thoroughly with water after development. It turns out that it is better. Examples 8 to 10 and Comparative Examples 3 to 4 An aluminum plate with a thickness of 0.24 mm was degreased by immersing it in a 7% aqueous sodium phosphate solution kept at 60°C, and after washing with water, pumice was suspended in water. While the liquid was running, I rubbed it with a nylon brush to make it grainy. Next, after washing with water, it was immersed for 30 to 60 seconds in a 5% aqueous solution of JIS No. 3 sodium silicate (SiO ₂ /Na ₂ molar ratio = 3.1 to 3.3) maintained at 70°C. After thoroughly washing it with water and drying it, apply a photosensitive liquid with the following composition.
Dry. The coating weight is 2.0g/ after drying.
It was ^m2 . 2-Hydroxyethyl methacrylate copolymer (described in Example 1 of British Patent No. 1505739)...0.7g p-Toluenesulfonic acid, a condensate of p-diazodiphenylamine and paraformaldehyde salt
…0.1g Oil Blue #603 (manufactured by Orient Chemical Industry Co., Ltd.)
…0.03g 2-methoxyethanol …6g Methanol …6g Ethylene dichloride …6g The PS plate thus obtained was exposed through a transparent negative original using a 30 ampere carbon arc lamp from a distance of 70 cm for 45 seconds, and was then exposed to light with the following composition. was immersed in a developer for 1 minute at 20°C, and then the surface was lightly rubbed with absorbent cotton to remove the photosensitive layer in the unexposed areas to obtain a lithographic printing plate. Sodium sulfite...3g Benzyl alcohol...30g Triethanolamine...20g Monoethanolamine...5g Sodium tert-butylnaphthalene sulfonate (Perex NBL, manufactured by Kao Atlas Co., Ltd.)...30g Water 1000ml Used in Example 2, 3 or 7 A lithographic printing plate was treated using the treatment liquid in the same manner as in Example 1. Comparative Examples 3 and 4 are those that underwent the same treatment as Comparative Examples 1 and 2. Example 1 for each lithographic printing plate thus obtained
In the same manner as in the case of , the number of sheets covered, dirt, and ink removal were examined. The results are shown in Table 3.

[Table] △Slightly poor, ○Good, ◎Very good From the results in Table 3, the lithographic printing plates made by the plate-making method of the present invention are compared with those made by the conventional method of washing thoroughly with water after development. It was found that the ink adhesion was significantly improved.

Claims (1)

[Claims] 1. Contains an anionic surfactant and at least one compound selected from the group consisting of polymerized phosphoric acid, an alkali metal salt thereof, and an organic phosphonic acid immediately after image exposure and development of a photosensitive lithographic printing plate without washing with water. A plate-making method characterized by processing with an aqueous solution.