JPH0414342B2 - - 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 to a plate-making method that uses less washing waste liquid and enables low-cost plate making. Conventionally, in the rinsing process after the development process, a large amount of water was used for rinsing, and the rinsing water was discharged as is after use, but in recent years, for reasons such as pollution prevention and securing water resources, rinsing water has been A method of repeated use is adopted. However, in the method of repeatedly using washing water, when a large amount of plates are washed with water over a long period of time, insoluble matter is generated in the washing water, and the washing water is supplied onto the plate through a nozzle in an automatic developing machine etc. In this case, this insoluble matter clogged the nozzle. In addition, when washing water is circulated through a filter, the filter may become clogged. Furthermore, although this insoluble matter is thought to be the cause, stains were sometimes caused in non-image areas during printing. Therefore, in this method, it is necessary to frequently renew the washing water.
It is necessary to interrupt the production of printing plates each time, resulting in problems such as poor working efficiency, and there is also the problem that a large amount of washing waste liquid is discharged, which has a large impact on the cost of plate making. Therefore, the inventors of the present invention have made extensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, an object of the present invention is to provide a plate-making method that can stably produce a large amount of printing plates over a long period of time and has good working efficiency. Another object of the present invention is to provide a plate-making method that allows low-cost plate-making with an extremely small amount of water washing waste after development. The above-mentioned objects of the present invention are to provide a plate-making method in which a photosensitive lithographic printing plate is imagewise exposed and developed, and then washed with washing water that is used repeatedly. This is achieved by a plate-making method characterized in that the amount of the agent added is 0.01 to 10% by weight in the washing water. Although the present invention is preferably applied to the plate-making method described in, for example, Japanese Patent Application No. 77017/1984, it may be applied to other known plate-making methods. The present invention will be explained in detail below. Examples of the complexing agent used in the present invention include EDTA (ethylenediaminetetraacetic acid) and its salts, NTA (nitrilotriacetic acid) and its salts,
CyDTA (cyclohexanediaminetetraacetic acid) and its salts, HEDTA (hydroxyethylethylenediaminetriacetic acid) and its salts, EHPG [ethylenebis(hydroxyphenylglycine)] and its salts,
Aminocarboxylic acids and their salts such as N-dihydroxyethylglycine and its salts, CMT

【formula】 CMOS

[Formula] Low molecular weight carboxylic acid salt, CA

[Formula] Hydroxycarboxylic acids and their salts such as citric acid and its salts, sodium maleate-sodium acrylate copolymer, sodium acrylate-
Polyelectrolytes such as sodium methacrylate copolymer, sodium polyacrylate, sodium polymaleate, sodium poly-α-hydroxyacrylate, and sodium polyitaconate, phosphate esters such as phytic acid and its salts, and sodium hexametaphosphate. Examples include polyphosphates. The above-mentioned polymer electrolyte preferably has a molecular weight of 80,000 or less. Among the complexing agents in the present invention, polydentate ligands, so-called chelating reagents, are preferable to monodentate ligands, and chelating reagents that form water-soluble chelate compounds are particularly preferable. Also, those having a group consisting of a carboxyl group and/or a salt thereof, especially 3 or more,
Those having 800 or less are preferable. As the salt, sodium salt and potassium salt are preferred. Preferred complexing agents in the present invention include EDTA and its salts, NTA and its salts,
Examples include CyDTA and its salts, CMT, CMOS, CA, and sodium hexametaphosphate. In the present invention, one type of complexing agent or a combination of two or more types can be used. The amount of complexing agent added is 0.01 to 10% by weight in the washing water, and 0.03 to 10% by weight.
5% by weight is preferred. The washing water used in the present invention further contains acetic acid, boric acid,
It may also contain acids such as nitric acid and phosphoric acid, or water-soluble alkali metal salts thereof. These acids and salts can be used alone or in combination of two or more. Particularly when the developer is alkaline, it is preferable to include it as a PH buffer. The washing water used in the present invention may further contain anionic surfactants, nonionic surfactants, and wetting agents such as ethylene glycol, glycerin, and polyethylene glycol. The total amount of components other than these complexing agents is preferably 0.1% by weight or less in the washing water. Preferred photosensitive lithographic printing plates according to the present invention include those having a photosensitive layer on a support containing, for example, a diazo compound or an o-quinonediazide compound as a photosensitive component, with diazo compounds being particularly preferred. As the o-quinonediazide compound, o-naphthoquinonediazide compounds are preferred, particularly o-naphthoquinonediazide sulfonic acid esters or o-naphthoquinonediazide carboxylic acid esters of aromatic hydroxy compounds, and o-naphthoquinonediazide sulfonic acid esters of aromatic amino compounds. Amide or o-naphthoquinonediazide compound amide is preferred, and the o-quinonediazide compound is preferably mixed with an alkali-soluble resin and coated on the support. The diazo compound is preferably water-insoluble and soluble in organic solvents. A typical example is p- described in Japanese Patent Publication No. 52-7364.
low-molecular-weight diazonium salts such as phenolic salts of diazodiphenylamine or fluorocabrate;
and salts of diazo resins, which are condensates of diazonium compounds and aldehydes. Examples of the salt of the diazo resin include an organic solvent-soluble salt of a paraformaldehyde cocondensate of 3-methoxydiphenylamine-4-diazonium chloride and 4-nitrodiphenylamine described in Japanese Patent Publication No. 49-48001; 2-methoxy-condensate of p-diazodiphenylamine and formaldehyde
Examples include 4-hydroxy-5-benzoylbenzenesulfonate. Among these diazo resin salts, hexafluorophosphate or 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonate, which is a condensate of p-diazodiphenylamine and formaldehyde, and the former is particularly preferred. be. These diazo compounds can be used alone by being coated on a support, but in order to improve the physical properties of the photosensitive layer, it is preferable to use them in combination with various resins. Examples of such resins include Sielac, polyvinyl alcohol derivatives, and JP-A-118802
Examples include a copolymer having an alcoholic hydroxyl group in the side chain described in JP-A-55-155355 and a copolymer having a phenolic hydroxyl group in the side chain described in JP-A-55-155355. Among these, at least 50% by weight of structural units represented by the following general formula.
Copolymer containing, general formula (In the formula, R ₁ represents a hydrogen atom or a methyl group,
_R2 represents a hydrogen atom, a methyl group, an ethyl group, or a chloromethyl group, and n is an integer of 1 to 10. ) and 1 monomer unit having an aromatic hydroxyl group
~80 mol%, and acrylic ester and/or
or 5 to 90 methacrylic acid ester monomer units
copolymers having an acid value of 10 to 200 are preferred, and the latter copolymers are particularly preferred. The photosensitive layer of the photosensitive lithographic printing plate used in the present invention may further contain additives such as dyes, plasticizers, and components imparting printout performance. A photosensitive layer having such a composition is coated onto a support using a solution in a suitable solvent. The coating amount of the photosensitive layer provided on the support is
0.1-7g/ ^m2 is preferable, more preferably 0.5-7g/m2
3g/ ^m2 . As the support used in the photosensitive lithographic printing plate, conventionally known supports can be used, such as paper, plastic laminated paper, metal plates such as aluminum, zinc, and copper, polyethylene terephthalate, polypropylene, Examples include plastic films such as cellulose acetate, metal plates having metals such as chromium and nickel on the surface, paper, and plastics. Among these supports, aluminum plates are particularly preferably used. The surface of these supports is preferably processed to make them hydrophilic, to prevent harmful reactions with the photosensitive layer provided thereon, and to improve adhesion. For example, in the case of an aluminum plate, after mechanical, chemical or electrochemical polishing, immersion treatment in an aqueous solution of sodium silicate, potassium fluorozirconate, phosphate, etc. or anodization treatment is performed. is preferred. The photosensitive lithographic printing plate is exposed through a transparent original to a light source rich in actinic rays, such as a carbon arc lamp, mercury lamp, metal halide lamp, or tungsten lamp, and then developed in a wet processing process. The developer used in the above development process is preferably an alkaline solution containing water as the main solvent, and in addition to the alkaline agent, organic solvents may also be used as necessary.
Those containing anionic surfactants, inorganic salts, etc. are used. Examples of alkaline agents include inorganic alkaline agents such as sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, tribasic sodium phosphate, sodium bicarbonate, sodium carbonate, potassium carbonate, and ammonium carbonate; Organic alkaline agents such as mono-, di- or triethanolamine or propanolamino are advantageously used. The content of the alkaline agent in the developer is preferably 0.05 to 4% by weight, more preferably 0.1 to 2% by weight. As the organic solvent, n-propyl alcohol,
Alcohols such as benzyl alcohol and glycol ethers such as ethylene glycol monophenyl ether are useful. The content of the organic solvent in the developer is preferably 0.5 to 15% by weight, more preferably 1 to 5% by weight. Examples of anionic surfactants include alkyl sulfate salts such as sodium lauryl sulfate, alkyl alysulfonates such as dodecylbenzenesulfonic acid, and sulfones of dibasic fatty acid esters such as sodium di(2-ethylhexyl)sulfosuccinate. Examples of acid salts include alkylnaphthalenesulfonates such as sodium n-butylnaphthalenesulfonate, polyoxyethylene alkyl (phenol) ether sulfates, etc. Among these, alkylnaphthalenesulfones such as n-butylnaphthalenesulfonic acid Acid acids are preferably used. The content of anionic surfactant in the developer is preferably 0.1 to 5% by weight, and 0.5 to 5% by weight.
A range of 1.5% by weight is more preferred. As the inorganic salt, alkali or alkaline earth water-soluble salts such as phosphoric acid, silicic acid, carbonic acid, sulfite, etc. are used, and alkali or alkaline earth sulfites are particularly preferably used. The content of the inorganic salt in the developer is in the range of 0.05 to 5% by weight, more preferably in the range of 0.1 to 1% by weight. It is also useful to further contain an antifoaming agent, a wetting agent, etc. in the developing solution, if necessary. Various conventionally known methods can be used to develop the photosensitive lithographic printing plate imagewise exposed with the above developer. Specifically, a method of immersing an image-exposed photosensitive lithographic printing plate in a developer;
Examples include a method of spraying a developer onto the photosensitive layer from a number of nozzles, a method of wiping the photosensitive layer with a sponge moistened with the developer, and a method of applying the developer to the surface of the photosensitive layer with a roller. Further, after the developer is applied to the photosensitive layer 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. The lithographic printing plate obtained by imagewise exposing and developing the photosensitive lithographic printing plate as described above is preferably squeezed prior to washing with water to reduce the amount of developer on the plate surface. . The amount of developer remaining on the printing plate after being squeezed is preferably 10 ml/m ² or less, particularly preferably 5 ml/m ² or less. Squeezing methods include, for example, passing a lithographic printing plate between a pair of elastic rollers whose surfaces are covered with an elastic member such as rubber, and removing the developer on the plate surface by the nip pressure, or using an elastic plastic material with a smooth surface. Adopt methods such as arranging the developer along the transport path of the lithographic printing plate and scraping off the developer on the plate surface by sliding it into contact with the plate surface, or scraping off the liquid on the plate surface with an air knife. I can do it. Among these methods, a method using a pair of rollers is preferably used because of the simplicity of the device. Methods for washing the photosensitive planographic printing plate with water after development include, for example, a method in which the planographic printing plate is immersed in a tank filled with washing water and preferably stirred and then taken out, and a spray pipe having a plurality of narrow openings is placed on the planographic printing plate. There are methods of supplying washing water through a pipe or the like. When an automatic processor is used, the latter method is advantageous, and the amount of washing water supplied is preferably in the range of 1 to 40 water per m ² of the planographic printing plate. In the present invention, the washing water is used repeatedly, and "used repeatedly" here means that at least a part of the water once used for washing is used again as washing water, preferably once. This means reusing more than half of the water used.
The method of the present invention is sufficiently effective even when the entire amount of washing water used once is reused. The washed lithographic printing plate is preferably squeezed to reduce the amount of washing water remaining on the plate surface, and the above-mentioned method can be used for the squeezing, but a method using a pair of rollers is preferable. . In addition, in the plate-making process of the lithographic printing plate, it is possible to provide various treatment processes as necessary after the water washing process. In other words, the steps that follow the water washing process include desensitization (gumming) treatment, treatment with a surfactant solution, developing ink build-up, erasing, etc., but the process after water washing is especially the desensitization (gumming) treatment. ) treatment or treatment with a surfactant solution, the effects of the present invention are remarkable. Next, an embodiment of an apparatus for carrying out the present invention will be described. FIG. 1 is a flow sheet showing one embodiment of the apparatus used to carry out the present invention. In the figure, 1 is a developing treatment tank, 2 is a circulation washing tank, and 3 is a desensitization treatment tank. 4, 5 and 6 are liquid feed pipes for sending the treatment liquid used in the tanks 1, 2 and 3 to the spray pipes described later, and 7, 8 and 9 are the liquid feed pipes 4, 3, respectively. 5,6
This is a pump installed in the and 10A, 10
B and 10C both have development treatment tank 1 on the printing plate surface.
A spray pipe is used to spray the processing liquid contained therein, and 11 is a spray pipe for spraying the processing liquid from the circulation washing tank 2, and 12 is a spray pipe for spraying the processing liquid from the desensitization treatment tank 3 onto the printing plate surface. 13
1 is a guide roller, 14 and 15 are conveyance rollers, 16 is a pedestal, and 17 is a brush roller. And 18, 19, 20, 21 and 22 are all squeeze rollers. 23 is an exposed photosensitive planographic printing plate, and 24 is a processed planographic printing plate. In the conventional plate-making method in which a photosensitive lithographic printing plate was exposed and developed imagewise and then washed with repeatedly used washing water, the washing water had to be replaced every few weeks, but the plate-making method of the present invention This method allows the process to be carried out for several months without having to be replaced. Hereinafter, the present invention will be explained in more detail with reference to specific examples, but the present invention is not limited thereto. Example 1 A grained aluminum plate with a thickness of 0.24 mm was anodized in sulfuric acid to form an oxide film of approximately 2 g/m ² , and after being thoroughly washed, it was immersed in a sodium silicate aqueous solution, thoroughly washed with water, and then dried. A photosensitive solution having the following composition was applied. Copolymer of p-hydroxyphenyl methacrylamide, acrylonitrile, ethyl acrylate, and methacrylic acid (molar ratios are in the order above)
8.5:24:60.5:7) 5.0 parts by weight Hexafluorophosphate of condensate of p-diazophenylamine and paraformaltehyde
0.5 parts by weight Victoria Pure Blue BOH (manufactured by Hodogaya Chemical Industry Co., Ltd.) 0.1 parts by weight Ethylene glycol monomethyl ether
100 parts by weight The coating amount after drying was 1.8 g/m ² . A number of sheets of the negative photosensitive lithographic printing plate obtained in this way were cut to a size of 800 mm x 1003 mm, and a transparent negative was passed through them from a distance of 80 cm using a 2 KW metal halide lamp to
Exposure for seconds. On the other hand, the developing tank 1 of the automatic processing machine shown in Fig. 1 was filled with 40 g of a developer having the following composition, and the circulating water washing tank 2 was filled with a solution of 40 g of ethylenediaminetetraacetic acid tetrasodium dihydrate dissolved in 16 g of tap water. The filling,
Add 15% of the desensitizing solution with the following composition to the desensitizing tank 3.
Filled. Developer ethylene glycol monophenyl ether
40 parts by weight diethanolamine 10 parts by weight Sodium n-butylnaphthalenesulfonate
12 parts by weight Antifoaming agent (trade name SM-5512, manufactured by Toray Silicone Co., Ltd.) 0.05 parts by weight Water 937 parts by weight Desensitizing liquid dextrin (trade name PENON JE-66, manufactured by Nippon Deka Chemical Co., Ltd.) 8 parts by weight Part carboxymethylcellulose sodium salt
0.45 parts by weight Phosphoric acid 0.2 parts by weight Polyethylene oxide (average number of added moles of ethylene oxide 19) Sodium nonylphenol ether sulfate 0.5 parts by weight Gum arabic 0.3 parts by weight p-hydroxyethyl benzoate 0.05 parts by weight Water 90 parts by weight Next, the above exposed A large number of photosensitive planographic printing plates were processed using the above automatic developing machine. Incidentally, the lithographic printing plate taken out from the desensitization treatment tank 3 was dried with hot air. Also, circulating water washing tank 2 and desensitizing treatment tank 3
The treatment solution was circulated and used. In this manner, 400 exposed photosensitive lithographic printing plates were processed in 6 days. Thereafter, after 4 months had elapsed with the processing solution as it was, the plate-making process was restarted, but no insoluble matter was observed in the circulating washing water. Another 400 sheets were processed in 6 days, and 50,000 sheets were printed on the 800th plate, but normal printed matter was obtained. As a comparative example, the same treatment as above was carried out, except that the circulating washing tank 2 of the automatic developing machine was filled with tap water. After 400 sheets were processed and 4 months passed, insoluble matter was observed in the circulating washing water. When the plate-making process was restarted and the 800th plate was printed, stains appeared during printing, which was thought to be caused by this insoluble material. As another comparative example, the circulation washing tank 2 of the automatic processor was filled with tap water 16 times, and the Example 1
Example 1 above except that 0.2% by weight of ethylenediaminetetraacetic acid tetrasodium dihydrate was added to the developer.
The same process was performed. 400 sheets were processed in 6 days, and after 4 months, insoluble matter was observed in the circulating washing water. When the plate-making process was restarted and the 800th plate was printed, stains appeared during printing, which was thought to be caused by this insoluble material. Example 2 The same automatic developer as used in Example 1 was used, and the same process as in Example 1 was carried out, except that an aqueous solution 16 in which CMT was dissolved in tap water at a rate of 3 g per 1 was used as the circulating washing water. Ta. Four months after the 400-plate treatment, no insoluble matter was generated in the washing water, and the same results as in Example 1 were obtained. Example 3 The same treatment as in Example 1 was carried out, except that an aqueous solution 16 in which trisodium nitrilotriacetic acid monohydrate was dissolved in well water at a rate of 5 g per well water was used as circulating water washing water. After 4 months of processing 400 plates, no insoluble matter was generated in the washing water, and the same results as in Example 1 were obtained. As a comparative example, the same treatment as above was carried out except that trisodium nitrilotriacetic acid monohydrate was omitted. Four months after processing the 400th plate, insoluble matter was found in the washing water. Example 4 Sodium acrylate-sodium methacrylate copolymer [trade name DURIMER AC-20N, molecular weight 50000 (25% solution)] was added to tap water as circulating water washing water.
The same treatment as in Example 1 was carried out, except that 2.5 g of Nippon Pure Chemical Industries, Ltd. (manufactured by Nippon Pure Chemical Industries, Ltd.) was used.
After 4 months of processing 400 plates, no insoluble matter was generated in the washing water, and the same results as in Example 1 were obtained.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing one embodiment of the apparatus used to carry out the method of the present invention. In the figure, 1 is a developing treatment tank, 2 is a circulation washing tank, 3 is a desensitization treatment tank, 7, 8 and 9 are pumps, and 10
A, 10B, 10C, 11 and 12 are processing liquid spray pipes, 18, 19, 20, 21 and 22 are squeeze rollers, 23 is a photosensitive planographic printing plate, 2
4 indicates a lithographic printing plate.

Claims (1)

[Claims] 1. In a plate-making method in which a photosensitive lithographic printing plate is imagewise exposed and developed and then washed with washing water that is used repeatedly, a complexing agent is added to the washing water, and the amount of the complexing agent added is equal to the washing water. A plate-making method characterized by a concentration of 0.01 to 10% by weight in water.