JPH0612443B2 - Developer composition of photosensitive lithographic printing plate and developing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a developer and a developing method for developing a photosensitive lithographic printing plate, and more specifically, a negative photosensitive lithographic printing plate. And a positive-working photosensitive lithographic printing plate in common, and a developing solution and a developing method.

[Conventional technology]

Conventionally, the negative photosensitive lithographic printing plate and the positive photosensitive lithographic printing plate have different compositions of developing solutions, and it has been possible to suitably develop only with the respective developing solutions (dedicated developing solutions). On the other hand, even if development can be performed using a developing solution that is not a dedicated developing solution, a lithographic printing plate having sufficient performance cannot be obtained.
It has been very difficult to commonly process the negative photosensitive lithographic printing plate and the positive photosensitive lithographic printing plate with one developing solution.

That is, a conventional developer for a negative-working photosensitive lithographic printing plate is relatively weakly alkaline, has a pH of about 10 to 11, and mostly contains an organic solvent. On the other hand, the developer for the positive type photosensitive lithographic printing plate is strongly alkaline with a pH of about 12.5 to 13. If the negative photosensitive lithographic printing plate developer is used to develop the positive photosensitive lithographic printing plate, the alkalinity is too weak to proceed with the development at all. On the contrary, when a negative photosensitive lithographic printing plate is developed with a positive photosensitive lithographic printing plate developing solution, no development is possible at all, or even if development is possible, ink stains are generated during printing.

In order to obtain a common developer capable of simultaneously processing a negative type photosensitive lithographic printing plate and a positive type photosensitive lithographic printing plate with one liquid, a method of mixing respective dedicated developing liquids at an appropriate ratio can be considered. However, it is not easy to obtain a suitable common developer. A developing solution for a negative photosensitive lithographic plate is disclosed in JP-A-53-44202.
It contains a poorly water-soluble organic solvent as described in JP-A Nos. 57-192951, 57-231536 and 60-97358. This is because the negative photosensitive lithographic printing plate is relatively soluble in an organic solvent. On the other hand, the positive-working photosensitive lithographic printing plate is a high pH strong alkaline aqueous solution containing no organic solvent. In order to produce the common developing solution, a developing solution in which the developing solutions of both plates are mixed is conceivable. However, the addition of a poorly water-soluble organic solvent causes the image area of the positive lithographic printing plate to be easily eroded and dissolved. But,
If the poorly water-soluble organic solvent is not contained, the developability of the negative photosensitive lithographic printing plate becomes extremely poor.

On the other hand, JP-A-60-64351 discloses a common developing method in which a negative photosensitive lithographic printing plate and a positive photosensitive lithographic printing plate are simultaneously developed with a single automatic developing solution. However, in this technique, each dedicated developer is put in each of the aligned developing baths, and the development for the negative type photosensitive lithographic printing plate and the development for the positive type photosensitive lithographic printing plate are successively performed. Instead of developing with one developer, two respective dedicated developers are used together. Therefore, liquid management is troublesome, and it is difficult to carry out stable development for a long time.

JP-A-60-130741 discloses a developer capable of developing a negative photosensitive lithographic printing plate and a positive photosensitive lithographic printing plate in common with one liquid. In this technique, an organic solvent of phenyl cellosolve or benzyl cellosolve, an anionic surfactant and an alkali agent containing an alkali metal hydroxide, silicate or tetrahosane salt are mainly used.
Although various photosensitive lithographic printing plates were developed using this developer, a tentative image was obtained, but the negative photosensitive lithographic printing plate had a drawback that ink stains were easily generated in non-image areas during printing. . In addition, precipitation may occur during storage.

[Object of the Invention]

It is an object of the present invention to provide a common developing solution having excellent developability, which enables good processing of a negative type photosensitive lithographic printing plate and a positive type photosensitive lithographic printing plate commonly with one liquid.

Another object of the present invention is to provide a method for developing a negative photosensitive lithographic printing plate and a positive photosensitive lithographic printing plate in one bath in common with a single automatic processor.

Another object of the present invention is to provide a developer having excellent stability that does not cause precipitation during long-term storage.

[Structure of Invention]

The object of the present invention is an alkali agent containing an alkali metal silicate, an organic solvent having a solubility in water at 20 ° C. of less than 10% by weight, an anionic surfactant, a sulfite and a solubility in water at 20 ° C. of 10% by weight or more. Developer composition of a photosensitive lithographic printing plate characterized by containing an organic solvent, and commonly processed negative-working photosensitive lithographic printing plate and positive-working photosensitive lithographic printing plate having an image forming layer on a support In the method for developing a lithographic printing plate described above, the above-mentioned developer composition is used in the range of pH 11.5 to pH 13.3.

That is, the present invention uses a poorly water-soluble organic solvent as an organic solvent in combination with a second organic solvent having a higher solubility in water than the solvent, and further has the above-mentioned additives to provide good developability and storage. It was possible to obtain a negative and positive common developer having excellent stability.

Hereinafter, the present invention will be described in detail.

The developer composition of the present invention contains an alkali metal silicate as an alkaline agent. Examples of alkali metal silicates include
There are potassium silicate, sodium silicate, lithium silicate, potassium metasilicate, sodium metasilicate, lithium metasilicate and the like. The amount of alkali metal silicate added is preferably 0.4 to 5.0% by weight in terms of SiO ₂ concentration. The developer composition of the present invention may use only an alkali metal silicate as an alkali agent, and it is also preferable to supplementarily use another alkali agent for the purpose of reducing pH fluctuation and improving the developability. . Examples of the alkaline agent include sodium borate, potassium borate, sodium triphosphate, sodium phosphate dibasic, potassium phosphate tribasic, ammonium phosphate tribasic, ammonium phosphate dibasic, sodium carbonate, sodium bicarbonate. , Potassium carbonate, ammonium carbonate, mono-, di-, or triethanolamine, tetraalkylammonium hydroxide and the like.

As the organic solvent having a solubility in water at 20 ° C. of the developer composition of the present invention of less than 10% by weight, for example,
Carboxylic esters such as ethyl acetate, propyl acetate, butyl acetate, benzyl acetate, methyl propyl ketone, methyl butyl ketone, methyl amine ketone, methyl isobutyl ketone, ethyl butyl ketone, ketones such as cyclohexanone, ethylene glycol monobutyl ether , Ethylene glycol monophenyl ether,
Glycols such as ethylene glycol monobenzyl ether, ethylene glycol butyl ether acetate, diethylene glycol butyl ether acetate, 1-
Pentanol, 2-pentanol, 3-pentanol,
2-methyl-4-butanol, 2-methyl-3-butanol, hexyl alcohol, heptyl alcohol, octyl alcohol, 2-phenylethanol, 3-phenylpropanol-1, 4-phenylbutanol-1, 4,
-Phenylbutanol-2,2-phenylbutanol-
1, o-methoxybenzyl alcohol, m-methoxybenzyl alcohol, p-methoxybenzyl alcohol,
Benzyl alcohol, cyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol,
Alcohols such as 4-methylcyclohexanol,
Examples include alkyl-substituted aromatic hydrocarbons such as xylene and toluene, halogenated hydrocarbons such as methylene chloride, ethylene chloride and monochlorobenzene.

Among these, ethylene glycol monophenyl ether, ethylene glycol benzyl ether and benzyl alcohol are particularly preferable.

The content of the organic solvent having a solubility in water at 20 ° C. of less than 10% by weight in the developer composition is 0.1 to 5% by weight, preferably 0.5 to 2% by weight. Further, more preferably, the solubility in water at 20 ° C. is preferably in the range of 0.1 to 5% by weight.

Examples of the organic solvent having a solubility in water at 20 ° C. of 10% by weight or more used in the present invention include, for example, methanol, ethanol, propanol, isopropanol, butanol, 2-methyl-1-propanol, and 3-methyl-3-.
Methoxybutanol, alcohols or substituted alcohols such as tert-butanol, acetone, ketones such as methyl ethyl ketone, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol diacetate, diethylene glycol,
Glycols such as diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, propylene glycol, ethylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, dioxane, N-
Examples include methylpyrrolidone and glycerol. Among these, alcohols and glycols are particularly preferable. The content of the organic solvent having a solubility in water of 10% by weight or more at 20 ° C. in the developer composition is 0.1 to 10% by weight, preferably 0.5 to 5% by weight. More preferably, it is an organic solvent freely soluble in water.

Examples of the anionic surfactant used in the developer composition of the present invention, higher alcohol (C ₈ ~ ₂₂₎ sulfates [e.g., sodium salt of lauryl alcohol sulfate, sodium salt of octyl alcohol sulfate,
Ammonium salt of lauryl alcohol sulfate,
"Taylor B-81" (trade name, sodium dodecylbenzene sulfonate manufactured by Shell Chemical Co., Ltd., secondary sodium alkyl sulfate, etc.), aliphatic alcohol phosphate salts (for example, sodium salt of cetyl alcohol phosphate ester), Alkylaryl sulfonates (eg, dodecylbenzene sulfonic acid sodium salt, isopropyl naphthalene sulfonic acid sodium salt, dinaphthalene disulfonic acid sodium salt, metanitrobenzene sulfonic acid sodium salt, etc.), alkyl amide sulfonates (eg, ), Dibasic fatty acid ester sulfonates (eg, sodium sulfosuccinate dioctyl ester,
Sodium sulfosuccinate dihexyl ester). Of these, sulfonates are particularly preferably used. The content of the anionic surfactant in the developer composition is 0.2 to 10% by weight, preferably 1 to 5% by weight. Further, the sulfite used in the developer composition of the present invention has a function of dissolving a water-insoluble diazo resin in an aqueous solution, and particularly, in the development of a lithographic printing plate comprising a photosensitive layer combined with a hydrophobic resin, It is possible to make a printing plate free from stains even with a plate material that has passed for a long period of time. As sulfite,
Alkali metals such as sodium, potassium and lithium and alkaline earth metal salts such as magnesium are useful.

The content of sulfite in the developer composition is 0.1 to 10
% By weight, preferably 0.2 to 5% by weight.

Further, the following additives may be added to the developer composition of the present invention in order to further enhance the developing performance. For example, neutral salts such as NaCl, KCl and KBr described in JP-A-58-75152, chelating agents such as EDTA and NTA described in JP-A-58-190952, and JP-A-59-121336. Of (CO (N
H _{3) 6]} Cl _3, sodium alkyl naphthalene sulfonate of COCl ₂ · 6H ₂ complex O etc., Sho 50-51324 JP,
Anionic or amphoteric surfactants such as N-tetradecyl-N, N-dihydroxyethylbetaine, US Pat. No. 4,37.
Nonionic surfactants such as tetramethyldecynediol described in JP-A No. 4,920, Cationic polymers such as quaternary methyl chloride of p-dimethylaminomethyl polystyrene described in JP-A-55-95946, 56-14
Ampholytic polyelectrolytes such as copolymers of vinylbenzyltrimethylammonium chloride and sodium acrylate described in JP-A-2528, and inorganic inorganic salts such as sodium sulfite described in JP-A-57-192952, JP-A-58- Inorganic lithium compounds such as lithium chloride described in JP-A-59444, JP-B-50
-34442 Organolithium compounds such as lithium benzoate, Organometallic surfactants containing Si, Ti, etc. described in JP-A-59-75255, Organoboron compounds described in JP-A-59-84241 Etc.

The developer composition of the present invention includes a developer used for developing a photosensitive lithographic printing plate, and a composition which is subjected to processing such as dilution and pH adjustment to obtain the developer.

The photosensitive lithographic printing plate to which the developer composition of the present invention is applied and the photosensitive lithographic printing plate used in the method of the present invention can be developed with a developer containing water as a main component and an alkaline agent, The photosensitive layer whose solubility is changed by light irradiation is coated on the support, or the soluble layer capable of providing an imagewise resist layer by an electrophotographic method or the like is provided on the support.

The support used in the photosensitive lithographic printing plate,
Paper, plastic (eg polyethylene, polypropylene, polystyrene, etc.) laminated paper, aluminum (including aluminum alloys), metal plates such as zinc, copper, cellulose diacetate, cellulose triacetate, cellulose propionate, polyethylene terephthalate, Films of plastics, such as polyethylene, polypropylene, polycarbonate, polyvinyl acetal, etc.
Examples include papers or plastic films laminated or vapor-deposited with metals as described above, steel plates plated with aluminum or chrome, and of these, aluminum and aluminum-coated composite supports are particularly preferable.

Further, the surface of the aluminum material is preferably roughened for the purpose of increasing water retention and improving adhesion to the photosensitive layer.

Examples of the roughening method include generally known brush polishing methods, ball polishing methods, electrolytic etching, chemical etching, liquid honing, sand blasting and the like, and combinations thereof, preferably brush polishing methods, electrolytic etching and chemical methods. Roughening methods involving the use of electrolytic etching and liquid honing, of which especially the use of electrolytic etching is preferred.

Further, as the electrolytic bath used in the electrolytic etching, an aqueous solution containing an acid, an alkali or a salt thereof or an aqueous solution containing an organic solvent is used, and among these, an electrolytic solution containing hydrochloric acid, nitric acid or a salt thereof is particularly used. Liquids are preferred.

Further, the surface-roughened aluminum plate is desmutted with an acid or alkali aqueous solution, if necessary.

The aluminum plate thus obtained is preferably anodized, and particularly preferably, a method of treating with a bath containing sulfuric acid or phosphoric acid can be mentioned. Further, surface treatment such as sealing treatment and immersion in an aqueous solution of potassium fluorozirconate may be carried out, if necessary.

The photosensitive layer of the photosensitive lithographic printing plate in the present invention contains a photosensitive substance as an essential component, and its physical and chemical properties are changed by exposure or subsequent development treatment as the photosensitive substance, for example, One that causes a difference in solubility in a developer upon exposure, one that causes a difference in intermolecular adhesion before and after exposure, one that causes a difference in affinity for water and oil due to exposure or subsequent development processing, and electrophotography A method in which an image portion can be formed by a method
The multi-layered structure described in JP-A-55-166645 can be used.

Representative examples of the photosensitive substance include, for example, a photosensitive diazo compound, a photosensitive diazo compound, a compound having an ethylenically unsaturated double bond, an epoxy compound which causes polymerization with an acid catalyst, and a COC-group which decomposes with an acid. And the like.

Typical positive-type compounds which change to be soluble in alkali upon exposure include o-quinonediazide compounds and acid-decomposable ether compounds and ester compounds, and negative-type compounds whose solubility decreases upon exposure are aromatic diazonium salts and the like. Is mentioned.

Specific examples of the o-quinonediazide compound include, for example, JP-A Nos. 47-5303, 48-63802, 48-63803 and 49.
-38701, 56-1044, 56-1045, and Japanese Examined Patent Publication 41-1
No. 1222, No. 43-28403, No. 45-9610, No. 49-17481, U.S. Patent Nos. 2,797,213, No. 3,046,120, No. 3,188,210, No. 454,400, No. 3,544,323, No. No. 3,573,917, No. 3,674,495, No. 3,785,825,
British Patents 1,227,602, 1,251,345, 1,267,
No. 005, No. 1,329,888, No. 1,330,932, German Patent No. 854,890, JP-A-60-37549, No. 60-10247,
Examples thereof include those described in each specification such as No. 60-3625, and at least the present invention is preferably applied to a photosensitive lithographic printing plate using these compounds alone or in combination as a photosensitive component. can do.

These photosensitive components include o-quinone diazide sulfonic acid ester of aromatic hydroxy compound or o-quinone diazide carboxylic acid ester and o of aromatic amino compound.
-Quinone diazide sulfonic acid or o-quinone diazide carboxylic acid amide is included, and those in which these o-quinone diazide compounds are used alone and those in which this mixture is provided as a photosensitive layer by mixing with an alkali-soluble resin are preferable.

The alkali-soluble resin includes novolac type phenol resin, and specifically includes phenol formaldehyde resin, cresol formaldehyde resin, phenol cresol mixed formaldehyde resin, cresol xylenol mixed formaldehyde resin and the like. Further, as described in JP-A-50-125806, a phenol or cresol and a formaldehyde substituted with an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin together with the above-mentioned phenol resin. What used together with the condensate of and is also applicable.

If necessary, the photosensitive layer containing the o-quinonediazide compound as a photosensitive component may further contain additives such as a dye, a plasticizer, and a component that imparts printout performance.

The present invention can be applied to a photosensitive layer containing an o-quinonediazide compound as a photosensitive component in an amount per unit area of preferably about 0.5 to 7 g / m ² .

The representative photosensitive component of the negative type photosensitive layer is a diazo compound, for example, a diazo resin which is a diazonium salt and / or a condensate of p-diazophenylamine and formaldehyde, and is described in JP-B-527364. P
Organic compounds of copolycondensates of 3-methoxydiphenylamine-4-diazonium chloride, 4-nitrodiphenylamine and formaldehyde described in JP-B-4948001 such as diazodiphenylamine phenol salt or fluorocaprate salt Diazo resin comprising solvent-soluble salt, 2-methoxy-4-hydroxy-5-condensate of p-diazodiphenylamine and formaldehyde
Examples thereof include benzoylbenzene sulfonate, tetrafluoroborate and hexafluorophosphate which are condensates of p-diazodiphenylamine and formaldehyde.

The image exposure of the photosensitive lithographic printing plate to which the invention is applied does not need to be particularly changed and may be carried out according to a conventional method.

The pH of the developer in the developing method of the present invention is in the range of 11.5 to 13.3, and the developability deteriorates when the pH is less than 11.5,
Ink stains easily occur, and when the pH exceeds 13.3, when the support of the photosensitive lithographic printing plate is aluminum, the surface thereof is corroded and the printing performance is deteriorated. Also, when using a support such as iron, there is no corrosion, but the image deteriorates,
It causes deterioration of printing durability.

In the developing method of the present invention, after the development processing step, if necessary, a development stop processing step (stop processing liquid includes a disposable method and a circulation use method), a desensitizing processing step, and individual development steps. Stop processing step and desensitization processing step succeeding it, processing step in combination with development processing step and desensitization processing, or combination of development stop processing step and desensitization processing step, for example, JP-A-54-8002 The processing steps described may be provided.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto.

Example 1 An aluminum plate having a thickness of 0.24 mm was immersed in a 20% sodium phosphate aqueous solution for degreasing, and this was 3 A / m ^{2 in a} 0.2 N hydrochloric acid bath.
After electropolishing at a current density of, anodizing was performed in a sulfuric acid bath. At this time, the amount of anodic oxidation was 4 g / m ² .

Further, sealing treatment was performed with an aqueous solution of sodium metasilicate to prepare an aluminum plate used for a stencil printing plate. Next, the following photosensitive solution A was applied onto the aluminum plate to obtain a negative photosensitive lithographic printing plate, and the photosensitive solution B was applied to obtain a positive photosensitive lithographic printing plate. The coating is carried out by a spin coater and dried at 100 ° C for 4 minutes, and the coating film weight is 2.5 g / m for both plates.
^{Was 2} .

[Photosensitive solution A] Copolymer of N- (4-hydroxyphenyl) methacrylamide: acrylonitrile: ethyl acrylate: methacrylic acid = 27: 33: 41: 6 (weight ratio) (acid value 80) .... 5. Hexafluorophosphate salt of paraform aldehyde condensate of 0 g p-diazodiphenylamine .... 0.5 g Julimer AC10L (trade name, manufactured by Nippon Pure Chemical Industries, Ltd., acrylic acid polymer) .... 0.05 g Tartaric acid .... 0.05g Victoria Pure Blue BOH (trade name, dye by Hodogaya Chemical Industry Co., Ltd.) ………… 0.1g Novolac resin (pp-3121) (manufactured by Gunei Chemical Co., Ltd.) ……… 0.15g Pluronic L-64 (trade name, manufactured by Asahi Denka Co., Ltd., surfactant) ………… 0.005 g Methyl cellosolve ……… 100 g [Photosensitive solution B] naphthoquinone- (1,2) -diazide- (2) -5 -Sulfo Condensation product of acid chloride and resorcin-benzaldehyde resin ………… 3.5g m-cresol-formaldehyde novolak resin “MP-707” (manufactured by Gunei Chemical Industry Co., Ltd.) …… 9g naphthoquinone- ( 1,2) -Diazide- (2) -4-sulfonic acid chloride: 0.15 g Victoria Pure Blue BOH (trade name, dye by Hodogaya Chemical Co., Ltd.): 0.2 g Methyl Cellsolve ……… 100g The photosensitive lithographic printing plate thus obtained had a density difference of 0.15
Was exposed using a 2 Kw metal halide lamp through a step wedge of. After that, the developer A (SiO ₂ 0.58
(% By weight) was used for development processing at 25 ° C. for 40 seconds by an automatic processor.

(Developer A) pH 12.50 The developed negative-working and positive-working plate printings gave good images, and when these printing plates were mounted on a Heidel GTO printing machine and printed on high-quality paper, stain-free prints were obtained.
Further, the above-mentioned developing solution did not cause any precipitation even when left standing for 6 months or more, and maintained stable developing property even after standing for a long time. In addition, when the same experiment was carried out by removing 3-methyl-3-methoxybutanol from the developing solution, the developing property of the negative photosensitive lithographic printing plate was one stage worse than that of the developing solution of the present invention by the number of wedge stages. When left for one week, a precipitate was formed, and the developability was further deteriorated.

Examples 2 to 6 Each of the negative-working and positive-working photosensitive lithographic printing plates shown in Example 1 was imagewise exposed in the same manner as in Example 1, and 40 ° C. at 20 ° C. using a developer having the composition shown in Table 1. Bat development was performed for 2 seconds, and the results shown in Table 3 were obtained.

Comparative Example 1 The same negative and positive photosensitive lithographic printing plates as those used in Example 1 were imagewise exposed in the same manner as in Example 1 and
When vat development was performed at 20 ° C. for 40 seconds with the developer having the composition shown in Table 2, the results shown in Table 3 were obtained.

As shown in Table-2, in Examples 2 to 6, good common development was possible, and printing could be performed without problems. On the other hand, in Comparative Example 1, the development was excellent, but the negative lithographic printing plate showed stains on the entire surface during printing. In Comparative Examples 2 and 3, the negative type lithographic printing plate had poor developability, and a precipitate was formed when left standing.

〔The invention's effect〕

The developer composition according to the present invention can develop a negative photosensitive lithographic printing plate and a positive photosensitive lithographic printing plate in common with good developability, and a good printing plate can be obtained. Further, the developer composition according to the present invention does not cause precipitation during long-term storage and is excellent in stability.

According to the method of the present invention, a negative-working photosensitive lithographic printing plate and a positive-working photosensitive lithographic printing plate can be commonly developed in one automatic imager and in one bath development processing.

In the developer composition of the present invention, the inclusion of an organic solvent having a solubility in water at 20 ° C. of 10% by weight or more serves to improve the solubility of the anionic surfactant and the sulfite in the developer composition. There is. Some of the anionic surfactants have poor solubility, but the use of the above solvent expands the selection range of the anionic surfactant. In addition, it is presumed that the second solvent is effective in that the developer composition of the present invention does not cause precipitation even when stored for a long period of time and can maintain stable developability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-53-44202 (JP, A) JP-A-56-72440 (JP, A) JP-A-60-130741 (JP, A) JP-A-57- 5045 (JP, A)

Claims (2)

[Claims] 1. A negative photosensitive lithographic printing plate having a photosensitive layer containing a photosensitive diazo resin on a support and a positive photosensitive lithographic plate having a photosensitive layer containing a 0-quinonediazide compound on the support. In a dual-use developer for printing plates, an alkali agent containing an alkali metal silicate, an organic solvent having a solubility in water at 20 ° C of less than 10% by weight, an anionic surfactant, a sulfite and a solubility in water at 20 ° C of 10% by weight. A developer composition comprising the above organic solvent. 2. A negative photosensitive lithographic printing plate having a photosensitive diazo resin-containing photosensitive layer on a support and a positive photosensitive lithographic printing plate having a 0-quinonediazide compound-containing photosensitive layer on a support. In the method for developing a photosensitive lithographic printing plate to be treated by, an alkali agent containing an alkali metal silicate, an organic solvent having a solubility in water at 20 ° C of less than 10% by weight, an anionic surfactant, a sulfite and water at 20 ° C. To a developer containing an organic solvent with a solubility of 10% by weight or more
A method for developing a photosensitive lithographic printing plate characterized by being used in the range of 1.5 to pH 13.3.