GB2276729A - Developers and replenishers for presensitised plates - Google Patents

Description

2276729 Developers for PS Plates and Replenishers Therefor The present

invention relates to a developer for presensitized plates for use in making lithographic printing plates as well as a replenisher for the developer.

The positive-working presensitized plate for use in making lithogr4phic printing plates (hereunder referred to as "(positive- working) PS plate") which:-have widely been used comprises an aluminum plate serving as a substrate and a lightsensitive layer comprising o- quinonediazide compound. It is known that the o-quinonediazide compound is converted into a carboxylic acid through irradiation with UV rays. Accordingly, only the exposed area of the light-sensitive layer is removed through development with an alkaline aqueous solution to thus expose the surface of the substrate. The surface of the aluminum substrate is hydrophilic and thus the surface of the substrate exposed through the development (non-image area) retains water, but repels oil- based inks. On the contrary, the area (image area) on the light-sensitive layer which is not removed through the development is lipophilic and repels water, but receive inks. There have been known various kinds of alkaline aqueous solutions used as developers for these positive-working PS 1 plates, but aqueous solutions of silicates such as sodium silicate and potassium silicate are most preferred. This is because, it is believed that the developing ability of such an alkaline aqueous solution can be controlled to some extent by changing the ratio of silicon oxide Si02 to alkali metal oxide M20 (in general, expressed in terms of molar ratio: [Si021/[M201) as components of a silicate and the concentrations of both components in the solution. - Moreover, automatic developing machines for PS plates have widely been employed in the field of the plate-making and printing to rationalize and standardize the plate-making operations. The automatic developing machine in general comprises a device for conveying a PS plate to be-processed, a bath for accommodating a developer and a device for spraying the developer and develops the PS plate by pumping up the developer and spraying it on the exposed PS plate through a spray nozzle while horizontally conveying the exposed PS plate. Alternatively, there has also been known a method which comprises conveying an exposed PS plate while immersing the plate in a developer contained in a developing bath by the action of submerged guide rolls.

Japanese Unexamined Patent Publication (hereunder referred to as I1J.P. KOKAP) No. Sho 54-62004 sets forth that when a positive-working PS plate is developed using such an automatic developing machine, a large number of PS plates can be processd without exchanging a developer in a tank over a long time period 2 through the use of an aqueous solution of sodium silicate having a molar ratio Of Si02 to Na20 ranging from 1.0 to 1.5 (i.e., [Si02]/[Na201 ranging from 1.0 to 1.5) and the Si02 content ranging from 1 to 4% by weight as a developer and through continuous or intermittent supplementation of an aqueous solution of sodium silicate (replenisher) having a molar ratio Of Si02 to Na20 ranging from 0.5 to 1.5 (i.e., [Si02]/[Na20] ranging from 0.5 to 1.5) to the developer.

Moreover, Japanese Patent Publication for Opposition Purpose (hereunder referred to as I'J.P. KOKOW') No. Sho 57- 7427 di;!closes a method of development in'which an aqueous solution of an alkali metal silicate haVing a ratio: [Si021/[M1 of 0.5 to 0.75 (i.e., [Si021/[M201 of 1.0 to 1.5) and an Si02 content of 1 to 4% by weight is used as a developer and an aqueous solution of an alkali metal silicate having a ratio:

[Si021/[M) of 0.25 to 0.75 (i.e., [Si021/[M201 of 0.5 to 1.5) and wherein both developer and replenisher contain at least 20% of potassium on the basis of the total gram atoms of. the alkali metals present therein.

It is known that the processing abilities of these developers mainly comprising these silicates can be enhanced if the alkalinity thereof is increased, but such a developer is inferior in developing stability.

As methods for ensuring developing stability while maintaining a high alkalinity, there have been known, for instance, a method comprising adding an anionic or amphoteric 3 surfactant as disclosed in J.P. KOKAI No. Sho 50-51324; a method comprising adding a water-soluble cationic polymer as disclosed in J.P. KOKAI No. Sho 55-95946; and a method comprising adding a water-soluble amphoteric polyelectrolyte as disclosed in J.P. KOKAI No. Sho 56-142528. However, all of these developers suffer from a problem in that they cause severe foaming upon stirring in an automatic developing machine and the developing machine gets contaminated.

In addition, various compounds have been-proposed as additives for achieving developing stability, for instance, organic.boron atom-containing compounds to which alkylene glycol is added such as those disclosed in J.P. KOKAI No. Sho 59-84241; polyoxyethylene/polyoxypropylene block polymer type water-soluble surfactants such as those disclosed in J.P. KOKAI No. Sho 60-111246; alkylenediamine compounds to which polyoxyethylene/polyoxypropylene is added such as those disclosed in J.P. KOKAI No. Sho 60-129750; polyethylene glycols having an average-molecular weight of not less than 300 such as those disclosed in J.P. KOKAI No. Sho 61-215554; fluorine atom containing surfactants carrying cationic groups such as those disclosed in J.P. KOKAI No. Sho 63-175858; and combinations of water-soluble ethylene oxide adducts obtained by adding at least 4 moles of ethylene oxide to acids or alcohols with water soluble polyalkylene compounds such as those disclosed in J.P.

KOKAI No. Hei 2-39157. Incidentally, the developer for PS plates are in general sold in the form of concentrates having a 4 -A concentration of 3 to 10 times that of the developer practically used, for the convenience of transportation. Thus, the plate-makers and printers dilute it to a desired level prior to the practical use thereof. However, the solubility of the foregoing water-soluble polyalkylene compounds in an aqueous silicate solution having a high concentration is very low and accordingly the concentration of a developer containing these water-soluble polyalkylene compounds is very difficult.

On the other hand, these silicates can be used for developing not only the aforementioned positive-working PS plates,.but.also reversal negative-working PS plates whose light-sensitive layer comprises o-quin6nediazide as disclosed in J.P. KOKOKU No. Sho 56-14970, negative-working PS plates whose light-sensitive layer comprises alkali-soluble diazonium salts, and negative-working PS plates whose light-sensitive layer comprises resins carrying,, on the side chains, dimethylmaleimido groups as photocrosslinking agents. In particular, both negative- and positive- working PS- plates have been processed in a common automatic developing machine for the purposes of reduction in the space occupied by the machine, elimination or reduction of labor and saving of natural resources. However, if the alkalinity of the developer is increased for improving the ability thereof to process positive-working PS plates, the ability thereof to process negative-working PS plates is substantially impaired and this makes the foregoing common processing impossible.

The present inventors have made extensive studies in the field of developers and replenishers wl-ih the aim of overcoming the defects noted above in the prior art.

Accordingly, an aim of the present invention is to provide a developer and a replenisher for the developer which has high developing stability over a long time period, is excellent in development capacity, has low foaming properties and is suitable for use, in particular, in an automatic developing machine as well as a replenisher for the developer.

Another aim of the present invention is to provide a developer for PS plates and a replenisher for the developer whos'e coqcentrates are excellent in storage stability.

A further 'aim of the present invention is to provide a developer suitably used in the processing of the negative- working PS plates in common with the positive-working PS plates and a replenisher for the developer.

The inventors of this invention have conducted various studies to accomplish the foregoing aims, have found out that these aims can be accomplished by adding a novel ethylene oxide adduct to a developer and/or a replenisher and thus have completed the present invention.

According to the present invention, there is provided a developer for PS plates which comprises an alkali metal silicate having a molar ratio: Si02/M20 (wherein M represents an alkali metal) ranging from 0.5 to 2.0 and a water-soluble ethylene oxide adduct obtained by adding not more than 5 moles of ethylene oxide to a sugar alcohol having not less than 4 6 hydroxyl groups.

According to another aspect Of the present invention, there is also provided a development replenisher for PS plates which comprises an alkali metal silicate having a molar ratio: SiO2/M20 (wherein M represents an alkali metal) ranging from 0.3 to 1.5 and a water-soluble ethylene oxide adduct obtained by adding not more than 5 moles of ethylene oxide to a sugar alcohol having not less than 4 hydroxyl groups.

Thq developer and the replenisher according to the present invention will hereunder be described in more detail.

Examples of alkali metal silicates usable in the developer of the present invention include sodium silicate, potassium silicate and lithium silicate and they may be used alone or in combination. The molar ratio: Si02/M2O (wherein M represents an alkali metal) of the alkali metal silicate ranges from 0.5 to 2.0. As the molar ratio increases, the developing ability of the resulting developer (in particular, the ability thereof to develop negative-working PS plates) is lowered and therefore, the molar ratio should be less than 2.0. On the other hand, the alkalinity of the developer increases as the molar ratio decreases and thus metals such as aluminum generally used as substrates for PS plates are attacked by the developer. This tendency becomes conspicuous in particular when the molar ratio is not more than 0.5. The concentration of the alkali metal 7 1 silicate in the developer preferably ranges from 1 to 10% by weight and in particular 1.5 to 5% by weight. If the concentration thereof exceeds 10% by weight, precipitates and/or crystals are easily separated from the developer. On the other hand, if it is less than 1% by weight, the resulting developer has a low developing ability.

On the other hand, examples of alkali metal silicates usable in the development replenisher of the present invention include sodium silicate, potassium silicate and lithium silicate and these silicates may be used alone or in combinal;ion. The molar ratio: SiO2/M20 of the alkali metal silicate ranges from 0.3 to 1.5. As thi; molar ratio increases, the developing ability of the resulting replenisher (in - particular, the ability thereof to develop negative-working PS 15 plates) is lowered and therefore, the molar ratio should be less than 1.5, while the alkalinity of the developer increases as the molar ratio decreases and thus metals such as aluminum generally used as substrates for PS plates are attacked by the resulting developer. This tendency becomes conspicuous in particular when the molar ratio is not more than 0.3. The concentration of the alkali metal silicate in the replenisher preferably ranges from 1 to 10% by weight and in particular 1.5 to 5% by weight. If the concentration thereof exceeds 10% by weight, precipitates and/or crystals are easily separated from the resulting replenisher, a large amount of silica gel is correspondingly formed through neutralization during disposal of 8 IQ waste liquid and this makes the post treatment of the waste liquid difficult. On the other hand, if it is less than 1% by weight, the resulting replenisher has only a low developing ability.

The developer and replenisher of the present invention may also comprise alkaline agents other than the alkali metal silicate. Examples of such alkaline agents are inorganic alkaline agents such as sodium tertiary phosphate, potassium tertiary phosphate, ammonium tertiary phosphate, sodium secondary phosphate, potassium secondary phosphate, ammonium secondary phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate,- potassium bicarbonate, ammonium bicarbonate, sodium borate, potassium borate, ammonium borate, sodium hydroxide, potassium hydroxide, ammonium hydroxide and lithium hydroxide. Examples of such alkaline agents also include organic alkaline agents such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolmine, diethanolmine, triethanolmine, monoisopropanolamine, diisopropanolamine, ethyleneimine, ethylenediamine and pyridine. These alkaline agents may be used alone or in combination.

The novel water-soluble ethylene oxide adduct usable in the developer and replenisher of the present invention is a compound obtained by adding not more than 5 moles of ethylene 9 oxide to a sugar alcohol having not less than 4 hydroxyl groups. The sugar alcohol used in the invention is a polyhydric alcohol corresponding to a sugar whose aldehyde and ketone groups are reduced into primary and secondary hydroxyl groups respectively. Specific examples of such sugar alcohols are D, Lthreitol, erythritol, D, L-arabitol, ribitol, xylitol, D, Lsorbitol, D, L-mannitol, D, L-iditol, D, L-talitol, dulcitol, allosulcite and di, tri, tetra, penta and hexa-glycerin.obtained through condensation of sugar alcohols. The water-soluble ethylene oxide adduct used in the invention can be obtained by addihS nqt less than 5 moles of ethylene oxide to one mole of the foregoing sugar alcohol. Propylefie oxide may be blockcopolymerized with the ethylene oxide adduct to such an extent that the solubility of the resulting product is not impaired.

These ethylene oxide a.dducts may be use'd alone or in combination.

In the developing step, the ethylene oxide adduct serves to make the penetration of the developer into an image area of an imagewise exposed PS plate slow through adsorption on-the image area and thus has a development-stabilizing effect. The use of a sugar alcohol having less than 4 hydroxyl groups does not ensure a sufficient development-stabilizing effect and causes reduction in the thickness of finelines. Moreover, if the molar number of added ethylene oxide is less than 5, only an insufficient developmentstabilizing effect would be attained. Therefore, the molar number of added ethylene oxide preferably 1 0 ranges from 5 to 50 and more preferably 5 to 30. In respect of the upper limit thereof, if it exceeds 50 moles, the speed of developing positiveworking PS plates is reduced, the resulting adduct has only a low solubility in a developer, and the adduct cannot be added to a concentrate of a developer or replenisher in an amount sufficient for accelerating the development of negative-working PS plates.

The amount of these water-soluble ethylene oxide adducts to be added to a developer preferably ranges from 0.001 to 5% by weight and more preferably 0.001 to 2% by weight on the basis of the weight of the developer practically used.

The developer and replenisher ot"the invention may, if desired, comprise various kinds of surfactants and/or organic solvents for accelerating development steps and for improving the dispersing ability of insoluble matters formed during the development and the lipophilicity of the image areas on the PS plates processed.

Examples of surfactants preferably used are nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrylphenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan f atty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol fatty acid monoesters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, 1 1 polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylene-modified castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2- hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters and trialkylamine oxides; anionic surfactants such as fatty acid salts, abietic acid salts, hydroxyalkanesulfonic acid salts, alkanesulfonic acid salts, salts of dialkylsulfosuccinic acid esters, linear alkylbenzenesulfonic acid salts, branched alkylbenzenesulfonic acid salts, alky1naphthalenesulfonic acid salts, alkylphenoxy poloxyethylene propylsulfonic acid salts, polyoxyethylene alkylsulfophenyl ether salts, sodiuffi salt of N-methyl-Noleyltaurine, disodium salts of N-alkylsulfosuccinic acid monoamides, petroleum sulfonic-acid salts, sulfated tallow oil, sulfuric acid ester salts of fatty acid alkyl esters, alkylsulfuric acid ester salts, polyoxyethylene alkyl ether sulfuric acid ester salts, fatty acid monoglyceride sulfuric acid ester salts, polyoxyethylene alkylphenyl ether sulfuric acid ester salts, polyoxyethylene styrylphenyl ether sulfuric 20. acid ester salts, alkyl phosphoric acid ester salts, polyoxyethylene alkyl ether phosphoric acid ester salts, polyoxyethylene alkylphenyl ether phosphoric acid ester salts, partially saponified products of styrene/maleic anhydride copolymers, partially saponified products of olefin/maleic anhydride copolymers and naphthalenesulfonic acid salts/formalin condensates; cationic surfactants such as alkylamine salts, 1 2 c A quaternary ammonium salts, polyoxyethylene alkylamine salts and polyethylene polyamine derivatives; amphoteric surfactants such as carboxy betaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid esters and imidazolines. The "polyoxyethylene" moiety of the foregoing surfactants can be replaced with polyoxyalkylene moieties such as polyoxymethylene, polyoxypropylene and polyoxybutylene and these surfactants can also be used in the present invention.

Examples of other surfactants preferably used.are fluorine atom-containing ones having, in the molecules, perfluoroalkyl groUps..Specific examples thereof include-anionic type ones such as perfluoroalkylearboxylic acid-salts, perfluoroalkyl sulfonic acid salts and perfluoroalkylphosphoric acid esters; a#hoteric type ones such as perfluoroalkyl betaines; cationic type ones such as perfluoroalkyl trimetbylammonium salts; and nonionic type ones such as perfluoroalkylamine oxides, perfluoroalkyl ethylene oxide adducts, oligomers carrying perfluoroalkyl groups and hydrophilic groups,.oligomers carrying perfluorbalkyl groups and lipophilic groups, oligomers carrying perfluoroalkyl groups, hydrophilic groups and lipophilic groups and urethanes carrying perfluoroalkyl groups and lipophilic groups.

The foregoing surfactants may be used alone or in combination and the amount thereof added to the developer preferably ranges from 0.001 to 10% by weight and more preferably 0.01 to 5% by weight.

1 1 3 The developer and replenisher of the present invention may, if desired, comprise organic solvents. They are preferably selected from those having solubility in water of not more than about 10% by weight, in particular not more than 5% by weight. Examples of the organic solvent include 1- phenylethanol, 2phenylethanol, 3-phenyl-l-propanol, 4-phenyl-l-butanol, 4phenyl-2-butanol, 2-phenyl-l-butanol, 2-phenoxyethanol, 2benzyloxyethanol, o-methoxybenzyl alcohol, m-methoxybenzyl alcohol, p- methoxybenzyl alcohol, benzyl alcohol, cyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 4-methylcyclbhex4nol, N-phenyl ethanolamine and N- phenyl diethanolamine. The amount of the organic solvents preferably ranges from 0.1 to 5% by weight with respect to the total weight of the developer practically employed. The amount of the organic solvent is closely related to that of the surfactant. More specifically, the amount of the surfactant is preferably increased with the increase in that of the organic solvent. This is because if the amount of the anionic surfactant is low and that of the organic solvent is great, the organic solvent is not completely solubilized in water and as a result, good developing properties of the developer or replenisher cannot be ensured.

The developer and replenisher according to the invention may further comprise a reducing agent for preventing the contamination of the resulting lithographic printing plate and this is particularly effective in the development of negative- 1 4 is working PS plates comprising light-sensitive diazonium salts. Examples of reducing agents preferably used in the invention are organic reducing agents, for instance, phenolic compounds such as thiosalicylic acid, hydroquinone, p-methyl amino phenol, methoxyquinone, resorcin and 2- methylresorcin; amine compounds such as phenylenediamine and phenyl hydrazine; and inorganic reducing agents such as sodium, potassium and ammonium salts of inorganic acids such as sulfinic acid, hydrosulfurous acid, phosphorous acid, hydrogenphosphorous acid, dihydrogenphosphorous acid, thiosulfuric acid and dithionous acid. Among these, those having particularly excellent effect of preventing contamination are sulfites. These-reducing agents are preferably used in an amount ranging from 0.05 to 5% by weight on the basis of the weight of the developer practically employed.

The developer and replenisher of the invention may also comprise an organic carboxylic acid. Preferred are aliphatic and aromatic carboxylic acids having 6 to 20 carbon atoms. Specific examples of the aliphatic carboxylic acids are caproic acid, enanthylic acid, caprilic. acid, lauric acid, myristic acid, palmitic acid and stearic acid with the alkanoic acids having 8 to 12 carbon atoms being particularly preferred. These aliphatic acids may be unsaturated ones having, in the carbon chain, double bonds or those having branched carbon chains. Examples of the aromatic carboxylic acids are compounds having carboxyl groups on the aromatic rings such as benzene, naphthalene and 1 5 anthracene rings, for instance, o-chlorobenzoic acid, pchlorobenzoic acid, o-hydroxybenzoic acid, p-hydroxybenzoic acid, o-aminobenzoic acid, p- aminobenzoic acid, pisopropylbenzoic acid, p-tert-butylbenzoic acid, p- sec- butylbenzoic acid, p-n-butylbenzoic acid, 2,4-dihydroxybenzoic acid, 2,5dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, gallic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 2hydroxy-1-naphthoic acid, 1-naphthoic acid and 2-naphthoic acid, with the hydroxynaphthoic acids being particularly effective. The'forqgoing aliphatic and aromatic carboxylic acids are preferably used in the form of sodium; potassium or ammonium salt for improving the solubility thereof in water. The amount of the organic carboxylic acids used in the developer and replenisher of the present invention is not restricted to a particular range. However, if they are used in an amount of less than 0.1% by weight, the desired effect thereof cannot be ensured, while if they are used in an amount of more than 10% by weight, any further effect thereof is not anticipated and if other additives are simultaneously used, they interrupt the dissolution thereof. Therefore, the amount of the carboxylic acids preferably ranges from 0.1 to 10% by weight and more preferably 0.5 to 4% by weight on the basis of the total weight of the developer practically used.

The developer and replenisher of the invention may optionally comprise additives such as antifoaming agents and/or 1 6 water softeners. Examples of water softeners include polyphosphoric acids and sodium, potassium and ammonium salts thereof; polyaminocarboxylic acids and salts thereof such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, 1, 2diaminocyclohexanetetraacetic acid and 1,3-diamino-2propanoltetraacetic acid, and ammonium, potassium and sodium salts thereof; aminotri(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), diethylenetridmingpenta(methylenephosphonic acid), triethylenetetraminehexa(methylenephosphonic acid), hydroxyethylethylenediaminetri(methylenephosphonic acid) and 1hydroxyethane-1,1-diphosphonic acid, and ammonium, potassium and sodium salts thereof.

The optimum amount of the water softener varies depending on the chelating ability of a specific softener, the hardness and the amount of hard water used, but the amount thereof in general ranges from 0.01 to 5% by weight and preferably 0.01 to 0.5% by weight on the basis of the total weight of the developer practically used. If the amount of the softener is less than the lower limit, the desired effect cannot be anticipated, while if it exceeds the upper limit, images are adversely affected and cause color blinding or the like.

The balance of the developer and replenisher of the invention is water, but they may optionally comprise other 1 7 1 various additives commonly known in the art. Examples of such additives include neutral salts such as NaCl, KCl and KBr as disclosed in J.P. KOKAI No. Sho 58-75152; complexes such as [Co(NH3)61C13 as disclosed in J. P. KOKAI No. Sho 58-121336; ionizable compounds of Group IIa, IIIa or IIIb elements in Periodic Table such as those disclosed in J.P. KOKAI No. Sho 55-25100; tetramethyldecyne diol as disclosed in U.S. Patent No. 4, 374,920; nonionic surfactants such as those disclosed in J.P. KOKAI No. Sho 60-213943; cationic polymers such as 10 methylchloride quaternary compounds of p-dimethylaminomethyl polystyiene as disclosed in J.P.-KOKAI No. Sho 55-95946; zwitter ionic polyelectrolytes such as cbpolymers of vinylbenzyl trimethylammonium chloride with sodium acrylate as disclosed in J.P. KOKAI No. Sho 56-142528; alkali-soluble mercapto or 15 thioether compounds such as those disclosed in J.P. KOKAI No. Sho 57-192952; inorganic lithium compounds such as lithium chloride as disclosed in J.P. KOKAI No. Sho 58-59444; organic lithium compounds such as lithium benzoate as disclosed in J.P. KOKOKU No. Sho 50-34442; organometal- containing surfactants 20 such as those containing Si and Ti disclosed in J.P. KOKAI No.

Sho 59-75255; organic boron atom-containing compounds such as those disclosed in J.P. KOKAI No. Sho 59-84241; quaternary ammonium salts such as tetraalkylammonium oxide as disclosed in European Patent No. 101,010; and germicides such as sodium 25 dehydroacetate as disclosed in J.P. KOKAI No. Sho 63-226657. It is preferred to prepare the developer and replenisher 1 8 in the form of concentrates having water contents lower than that in practically used ones and dilute them prior to use from the viewpoint of transportation. In this case, the degree of concentration is preferably selected such that each component does not cause any separation and precipitation.

PS plates which can suitably be developed with the developer and replenisher of the invention include, for instance, those having positiveworking light-sensitive layers comprising o-quinonediazide compounds as light-sensitive components (optionally used in the f orm of negative-working PS plates tbrough reversing) and negative-working PS plates having various kinds of photohardenable light-sensitive layers. In particular, the developer and replenisher of the present invention are excellent in that they can achieve a sufficient developing speed for negative-working PS plates when the positive-working PS plates are processed in common with the negative-working PS plates.

The PS plates to which the developer and replenisher of the invention are preferably applied will hereunder be explained in more detail.

(Substrate] The substrates used for the production of these PS plates processed with the developer and replenisher of the present invention are dimensionally stable plate-like materials and include, for example, paper,paper laminated with a plastic film 1 9 1 (such as polyethylene, polypropylene or polystyrene film) and metal plates such as aluminum (including alloys thereof), zinc, iron and copper plates, with the optimum effect of the invention being achieved by metal plates, in particular aluminum plate. Preferred aluminum plates are, for instance, those of pure aluminum or an aluminum alloy which mainly comprises aluminum and a trace amount of other elements as well as plastic films laminated with an aluminum film or on which aluminum is vapor-deposited. The aluminum plate used in the invention has a thickness in the order of about 0.1 to 0.6 mm.

Sugh an aluminum plate is optionally degreased, prior to the surface graining treatment, witb an aqueous solution containing a surfactant or an alkali or an organic solvent to remove the rolling oil from the surface thereof.

First, an aluminum plate used as a substrate is surface- roughened. Such surface-roughening treatments usable herein are, for instance, mechanical surface-roughening treatments, methods for electrochemically dissolving the surface and methods for chemically selectively dissolving the surface. The mechanical surface-roughening treatments can be carried out by any known methods such as ball graining, brush graining, blast graining and buff graining methods. In addition, the electrochemical surface-roughening treatment is, for instance, performed by passing an alternating or direct current through the aluminum plate in an electrolyte such as hydrochloric acid or nitric acid. Moreover, it is also possible to use combinations of these 2 0 two kinds of methods as disclosed in J.P. KOKAI No. Sho 5463902.

The aluminum plate thus surface-roughened may optionally be subjected to alkali etching and neutralization treatments and thereafter, anodized for improving the water retention and wear resistance of the surface. Any electrolyte can be used in the anodization treatment of this aluminum plate so far as they can form a porous anodized layer thereon and generally include, for instance, sulfuric acid, phosphoric acid, oxalic acid, chromic acid or mixture thereof. The concentration of these elec'trol_vtes are appropriately determined depending on the kinds of the electrolytes selected.

The conditions for the anodization may vary depending on the kinds of the electrolytes selected, but in general the anodization is preferably performed At an electrolyte concentration ranging from 1 to 80% by weight, an electrolyte temperature ranging from 5 to 70C, a current density ranging from 5 to 60 A/dM2, a voltage ranging from 1 to 100 V and an anodization time ranging from 10 seconds to 5 minutes.

The amount of the anodized layer is preferably not less than 1.0 g/M2 and more preferably 2.0 to 6.0 g/M2. This is because if it is less than 1.0 g/M2, the resulting lithographic printing plate has insufficient printing durability and the non-image portion thereof is easily damaged, which leads to the occurrence of so-called "contamination due to defects", i.e., the adhesion of ink to defects during printing operation.

2 1 In this respect, such an anodization treatment is applied to the face of the substrate which serves as the printing surface of the resulting lithographic printing plate, but an anodized layer having a thickness ranging from 0.01 to 3 g/M2 is generally formed on the back face thereof since lines of electric force partially pass around behind the substrate during the anodization treatment.

After the foregoing anodization treatment, the.aluminum plate is then hydrophilized, if desired. The hydrophilization thereof can be carried out by, for instance, an alkali metal silicatq (such as an aqueous sodium silicate solution) treatment as disclosed in U. S. Patent Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. In this method, a substrate is treated by immersing or electrolyzing in an aqueous solution of sodium silicate.

Examples of other hydrophilization treatments usable herein are treatments with potassium fluorozirconate as disclosed in J.P. KOKOKU No. Sho 36-22063 and a treatment with polyvinyl phosphonic acid as disclosed in U.S. Patent Nos.

3,276,868, 4,153,461 and 4,689,272.

[Organic Underlying Layer] An organic underlying layer or an intermediate layer is also applied, if desired, onto the aluminum plate prior to the application of a light-sensitive layer. Organic compounds used in the organic underlying layer are, for instance, carboxymethyl 2 2 cellulose, dextrin, gum arabic; phosphonic acids each having an amino group such as 2-aminoethyl phosphonic acid; organic phosphonic acids which may have substituents such as phenyl phosphonic acids, naphthyl phosphonic acids, alkyl phosphonic acids, glycerophosphonic acids, methylene diphosphonic acids and ethylene diphosphonic acids; organic phosphoric acids optionally having substituents such as phenyl phosphoric acids, naphthyl phosphoric acids, alkyl phosphoric acids and glycerophosphoric acids; organic phosphinic acids optionally having substituents such as phenyl phosphinic acids, naphthyl phosphinic acids, alkyl phosphinic acids and glycerophosphinic acids; amino acids such as Slyerne and 8 -alanine; hydrochlorides of amines having hydroxyl groups such as triethanolamine hydrochloride, which may be used alone or in combination.

The pH value of the solution for-preparing the underlying layer may be adjusted to 1 to 12 with a basic substance such as ammonia, triethylamine or potassium hydroxide or-an acidic substance such as hydrochloric acid or phosphoric acid.

Moreover, a yellow dye can be added for the improvement of tone reproduction of the PS plates.

The coated amount (weighed after drying) of the organic underlying layer suitably ranges from 2 to 200 MS/M2, preferably 5 to 100 Mg/M2. This is because, if the coated amount is less than 2 Mg/M2, the intended effects of the invention such as inhibition of contamination cannot be ensured, while if it 2 3 exceeds 200 Mg/M2' the resulting lithogaphic printing plate does not have sufficient printing durability.

An intermadiate layer may likewise be applied to the substrate for improving the adhesion between the substrate and a light-sensitive layer subsequently applied thereto. The intermediate layer in general comprises a diazo resin or a phosphoric acid compound capable of being adsorbed on an aluminum surface for the improvement of adhesion.

The intermediate layer may have any thickness, but the thickness thereof must be selected such that the layer can undergo.a uniform linkage-forming reaction with the lightsensitive-layer subsequently applied t1fereto, upon exposure to light. In general, the amount of the intermediate layer preferably ranges from about 1 to 100 Mg/M2 and in particular 5 to 40 mg/m2 (expressed in terms of the weight of the dried solid components).

The amount of the diazo resin used in the intermediate layer ranges from 30 to 100% by weight and preferably 60 to 100% by weight.

[Back Coat Layer] The developer or replenisher of the present invention has a relatively high alkalinity and, therefore, a back coat layer is preferably applied onto the PS plate processed with the developer and/or replenisher of the invention in order to inhibit any dissolution of aluminum oxide from the back face of 2 4 1 the plate. Such a back coat layer usable herein may be, for instance, those disclosed in J.P. KOKAI Nos. Hei 5-45885 and Hei 5-210235 and Japanese Patent Application Serial (hereunder referred to as I1J.P.A.") No. Hei 4-189448.

Light-Sensitive Layer A PS plate is produced by applying a light-sensitive layer of a known light-sensitive composition onto the aluminum plate thus obtained whose surface has been hydrophilized. The light- sensitive composition may be a positive-working light-sensitive compbsitOn which mainly comprises an o-quinonediazide compound; or a negative-working light-sensitfve composition wh ich comprises, as a light- sensitive substance, a photopolymerizable compound mainly composed of a diazonium salt, an alkali-soluble diazonium salt or an unsaturated double bond-containing monomer, or a photocrosslinkable compound having a cinnamic acid or dimethylmaleimido group.

[Positive-Working Light-Sensitive Layer] Examples of o-naphthoquinonediazide compounds used in the positive-working light-sensitive composition preferably include esters of 1,2-diazonaphthoquinonesulfonic acid with pyrogallol acetone resin as disclosed in J.P. KOKOKU No. Sho 43-28403 (U.S. Pat. No. 3,635,709). Other preferred o-quinonediazide compounds are, for instance, esters of 1,2-diazonaphthoquinone-5-sulfonic acid with phenol-formaldehyde resin as disclosed in 2 5 U.S. Patent Nos. 3,046,120 and 3,188,210; and esters of 1, 2diazonaphthoquinone-4-sulfonic acid with phenol-formaldehyde resin as disclosed in J.P. KOKAI Nos. Hei 2-96163, Hei 2-96165 and Hei 2-96761. Examples of other preferred o-naphthoquinonediazide compounds include those known and disclosed in a variety of patents such as J.P. KOKAI Nos. Sho 47-5303, Sho 48-63802, Sho 48-63803, Sho 48-96575, Sho 49-38701 and Sho 48-13354, J.P. KOKOKU Nos. Sho 37-18015, Sho 41-11222, Sho 45-9610 and Sho 4917481, U.S. Patent Nos. 2,797,213; 3,454,400;.3,544,323; 3,573,917; 3,674,495 and 3,785,825; U.K. Patent Nos. 1,227,602; 1,251,3k5; 1,267,005; 1,329,888 and 1,330,932; and German Patent No. 854, 890.

Particularly preferred o-naphthoquinonediazide compounds are those obtained through the reactionof polyhydroxy compounds having molecular weight of not more than 1,000 with 1,2- diazonaphthoquinonesulfonic acid. Specific examples thereof are those disclosed in, for instance, J.P. KOKAI Nos. Sho 51139402, Sho 58-150948, Sho 58-203434, Sho 59-165053, Sho 60121445, Sho 60-134235, Sho 60-163043, Sho 61-118744, Sho 6210645, Sho 62-10646, Sho 62-153950, Sho 62-178562 and Sho 6476047; and U.S. Patent Nos. 3,102,809; 3,126,281; 3,130,047; 3, 148,983; 3,184,310; 3,188,210 and 4,639,406.

The light-sensitive composition used in the invention preferably comprises the positive-working photosensitive compounds (inclusive of the foregoing combination) in an amount ranging from 10 to 50% by weight and more preferably 15 to 40% 2 6 1 by weight on the basis of the total weight of the composition.

The o-quinonediazide compound may form a light-sensitive layer by itself, but preferably it is used in combination with an alkali water-soluble resin as a binder. Examples of such alkali water-soluble resins are novolak resins such as phenolformaldehyde resins and cresol-formaldehyde resins, for instance, o-, m- and p-cresol-formaldehyde resins, M-/p- mixed cresol-formaldehyde resins and phenol-mixed cresol (m-/ p-/oor m-/p- or m-/o-)-formaldehyde resins.

Other binders usable in the invention further include phedol-mgdified xylene resins, polyhydroxystyrenes, halogenated polyhydroxystyrenes and acrylic resins having phenolic hydroxyl groups as disclosed in J.P. KOKAI No. Sho 51-34711.

Examples of suitable binders may further include copolymers generally having a molecular weight of 10,000 to 200,000 and having structural units derived from the following monomers (1) to (13).

(1) (Meth)acrylamides, (meth)acrylic acid esters and hydroxystyrenes having an aromatic hydroxy group such as N-(4- hydroxyphenyl) (meth)acrylamide, o-, m- or p-hydroxystyrene and o-, m- or p-hydroxyphenyl (meth)acrylate.

(2) (Meth)acrylic acid esters having an aliphatic hydroxy group such as 2hydroxyethyl (meth)acrylate.

(3) Unsuturated carboxylic adids such as (meth)acrylic acid, maleic anhydride and itaconic acid.

(Substituted) acrylates such as methyl acrylate, ethyl 2 7 acrylate, prOPyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, phenyl acrylate, benzyl acrylate, 2- chloroethyl acrylate, 4-hydroxybutyl acrylate, glycidyl aerylate and Ndimethylaminoethyl acrylate. (5) (Substituted) methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2chloroethyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate and N-dimethylaminoethyl methacrylate.

(6) - (Mpth)acrylamides such as (meth)acrylamide, N-methylol (meth)acrylamide, N-ethyl (meth)acrylamide, N-hexyl (meth) acrylamide, Ncyclohexyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, N-phenyl (meth)acrylamide, N-benzyl (meth) aerylamide, N-nitrophenyl (meth)acrylamide and N-ethyl-N-phenyl (meth)acrylamide.

(7) Vinyl ethers such as ethy 1 vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether and phenyl vinyl ether.

(8) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.

(9) Styrenes such as styrene, methylstyrene and chloromethylstyrene.

(10) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl 25 ketone, propyl vinyl ketone and phenyl vinyl ketone.

(11) Olefins such as ethylene, propylene, isobutylene, 2 8 1 butadiene and isoprene.

(12) N-vinyl pyrrolidone, N-vinyl carbazole, 4-vinyl pyridine and (meth)acrylonitrile.

(13) Unsaturated sulfonamides of (meth)acrylamides such as N(oaminosulfonylphenyl) (meth)acrylamide, N-(m-aminosulfonylphenyl) (meth)acrylamide, N-(p-aminosulfonylphenyl)(meth)acrylamide, N-[I-(3aminosulfonyl)naphthyl] (meth)acrylamide and N(2-aminosulfonylethyl) (meth)acrylamide; and unsaturated sulfonamides of (meth)acrylic acid esters such as o-amino- sulfonylphenyl (meth)acrylate, m-aminosulfonylphenyl (meth) acrylate, p- aminosulfonylphenyl (meth)acrylate and 1-(3aminosulfonylnaphthyl) (meth)acrylate.

Further, the foregoing monomers may likewise be copolymerized with other monomers copolymerizable therewith and the copolymers of the monomers listed above can be modified with, for instance, glycidyl (meth)acrylate. However, the copolymers usable in the invention are not limited to these specific examples.

The foregoing copolymers preferably comprises moieties derived from the unsaturated carboxylic acids (3) listed above and the carboxylic acid value thereof preferably ranges from 0 to 10 meq/g, more preferably 0.2 to 5.0 meq/g.

Preferred molecular weight of these copolymers ranges from 10,000 to 100, 000.

The foregoing copolymers, if desired, may comprise polyvinyl butyral resin, polyurethane resin, polyamide resin 2 9 and/or epoxy resin.

These alkali-soluble polymers may be used alone or in combination and the amount thereof is not more than 80% by weight on the basis of the total weight of the light-sensitive composition.

It is preferred for the improvement of ink-receptiVity of images formed on a lithographic printing plate to simultaneously use the foregoing polymer and a condensate of a phenol-carrying an alkyl group having 3 to 8 carbon atoms with formaldehyde such as t-butylphenol-formaldehyde resin or octylphenolformdLldebyde resin as disclosed in U.S. Patent No. 4,123,279.

The light-sensitive composition--- used in the invention preferably comprises, for the improvement of sensitivity, cyclic acid anhydrides, phenols, organic acids and/or higher-alcohols.

Examples of such cyclic acid anhydrides are phthalic anhydride, tetrahydro-phthalic anhydrid e, hexahydrophthalic anhydride, 3, 6-endoxyA 4 -tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, a -phenylmaleic anhydride, succinic anhydride and pyromellitic anhydride.

Such phenols include, for instance, bisphenol A, p nitrophenol, p-ethoxyphenol, 2,4,41-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxy-benzophenone, 4,41,411 tpihydroxy-triphenylmethane and 4,4',3'',411-tetrahydroxy 3,5,3',51-tetramethyltriphenylmethane.

Such organic acids are, for instance, sulfonic acids, 3 0 sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphoric acid esters and carboxylic acids as disclosed in J.P. KOKAI Nos. Sho 60-88942 and Hei 2-96755.

The content of the foregoing cyclic acid anhydrides, phenols and/or organic acids in the photosensitive composition preferably ranges from 0.05 to 15% by weight and more preferably 0.1 to 5% by weight on the basis of the total weight of the composition.

The composition used in the invention may further comprise, for enhancing the processing stability against the devdlopng conditions (i.e., for extending the development latitude), non-ionic surfactants as disclosed in J.P. KOKAI No.

Sho 62-251740 and J.P.A. No. Hei 2-188 and/or amphoteric surfactants as disclosed in J.P. KOKAI No. Sho 59-121044 and Hei 4-13149.

The content of the foregoing non-ionic and/or amphoteric surfactants in the composition ranges from 0.05 to 15% by weight and more preferably 0.1 to 5% by weight on the basis of the total weight of the composition.

The positive-working light-sensitive composition to be processed by the developer and/or replenisher of the present invention may comprise a printing out agent for obtaining a visible image immediately after exposure to light as well as a dye or pigment for coloring images.

A representative example of the printing out agent is a combination of a light-sensitive compound capable of releasing 3 1 an acid through exposure to light (a photolytically acidgenerating agent) with a salt-forming organic dye, for instance, a combination of onaphthoquinonediazido-4-sulfonic acid halide with a salt-forming organic dye as disclosed in J.P. KOKAI Nos. Sho 50-36209 and Sho 53-8128; and a combination of a trihalomethyl compound with a salt-forming organic dye as disclosed in J.P. KOKAI Nos. Sho 53-36223, Sho 54-74728, Sho 603626, Sho 61-143748, Sho 61-151644 and Sho 63-584_40. Such trihalomethyl compounds include oxazole and triazine type compounds and both of these are excellent in stability with time and tan provide clear printed out images.

Other dyes may also be used instbad of or together with the foregoing salt-forming organic dyes as the agents for coloring images. Preferred dyes inclusive of the salt-forming organic dyes are, for instance, oil-soluble and basic dyes.

Specific examples thereof are Oil Yellow #101 and #103, Oil Pink #312, Oil Green BG, Oil Blue BOS and #603, Oil Black BY, BS and T-505 (they are all available from Orient Chemical Industries, Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI 42555), Methyl Violet (CI 42535), Ethyl Violet, Rhodamine B (CI 145170B), Malachite Green (CI 42000) and Methylene Blue (CI 52015). Particularly preferred are those disclosed in J.P.

KOKAI No. Sho 62-293247.

The positive-working light-sensitive composition used in the invention is dissolved in a solvent in which the foregoing components are soluble and then applied onto the aluminum 3 2 substrate. Examples of solvents used herein are organic solvents as disclosed in J.P. KOKAI No. Sho 62-251739 which may be used alone or in combination.

The positive-working light-sensitive composition is dissolved and dispersed in the solvent in a concentration ranging from 2 to 50% by weight (solid content), applied to the substrate and then dried.

The coated amount of the positive-working light-sensitive composition (or the light-sensitive layer) applied onto the substrate varies depending on the applications of the resulting _plate, bt preferably ranges from 0.3 to 4.0 S/M2 (weighed after drying). As the coated amount decreages, the exposure value required for forming images is reduced, but the strength of the resulting film is impaired. On the other hand, as the coated amount increases, a high exposure value is required for the formation of images, but the strength of the film increases and accordingly, if the plate is, for instance, used as a lithographic printing plate, the plate having such a thick light-sensitive layer (i.e., image area) can provide a large number of acceptable copies (i.e., the plate has high printing durability).

The positive-working light-sensitive composition may comprise a surfactant such as a fluorine atom-containing surfactant as disclosed in J.P. KOKAI No. Sho 62-170950 for improving the coating properties thereof. The amount thereof to be added preferably ranges from 0.001 to 1.0% by weight and more preferably 0.005 to 0.5% by weight on the basis of the total weight of the composition.

[Negative-Working Light-Sensitive Layer] Then examples of light-sensitive compositions used in negative-working PS plates, which are processed with the developer and replenisher of the present invention, are lightsensitive compositions comprising light- sensitive diazo compounds, photopolymerizable light-sensitive compositions and photocrosslinkable light-sensitive compositions. Among these, photohardenable light-sensitive copying materials comprising light- sensitive diazo compounds will he detailed below with reference to specific examples.

The light-sensitive diazo compounds suitably used in the light-sensitive copying material are, for instance, diazo resins obtained through condensation of aromatic diazonium salts with reactive carbonyl groupcontaining organic condensation agents, in particular, aldehydes such as formaldehyde and acetaldehyde or acetals in acidic mediums, with a condensate of p-diazodiphenylamine with formaldehyde being most typical example thereof. Methods for synthesizing these diazo resins are detailed in, for instance, U.S. Patent Nos. 2,679,498; 3,050,502; 3,311,605 and 3, 277,074.

In addition, light-sensitive diazo compounds preferably used in the invention further include, for instance, diazo compounds obtained through co-condensation of aromatic 3 4 t- diazonium salts with substituted aromatic compounds free of diazonium group as disclosed in J.P. KOKOKU No. Sho 49-48001, with diazo compounds obtained by co-condensing aromatic diazonium salts with aromatic compounds substituted with alkali- soluble groups such as carboxyl and/or hydroxyl groups being particularly preferred.

Moreover, light-sensitive diazo compounds preferably used in the invention also include, for instance, condensates of reactive carbonyl group-containing compounds having alkali- soluble groups with aromatic diazonium compounds as disclosed in X.P. UOKAI Nos. Hei 4-18559, Hei 4-190361 and Hei 4-172354.

Examples of PS plates in which diazonium salts having alkali-soluble groups in the molecules are used as light'P. KOKAI Nos. Hei sensitive agents include those disclosed in J.

3-2846, Hei 3-5754, Hei 3-240061, Hei 3-253857, Hei 4-172354, Hei 4-211253, Hei 4-219759, Hei 4-274429 and Hei 5-5984. The developer and replenisher of the present invention are likewise preferably applied to these PS plates.

There have been known diazo resins in which the counteranions of these diazonium salts are inorganic anions such as those derived from mineral acids, e.g., hydrochloric acid, hydrobromic.acid, sulfuric acid and phosphoric acid or complex salts thereof with zinc chloride. However, particularly preferred are diazo resins which are substantially insoluble in water and soluble in organic solvents. Such preferred diazo resins are detailed in J.P. KOKOKU No. Sho 47-1167 and U.S.

3 5 Patent No. 3,300,309.

Moreover, preferred diazo resins further include, for instance, those having counteranions derived from halogenated Lewis acids such as tetrafluoroboric acid and hexafluoro- phosphoric acid and perhalogenic acids such as perchloric acid and periodic acid as disclosed in J.P. KOKAI Nos. Sho 54-98613 and Sho 56- 121031.

In addition, preferred are also include diazo resins having counteranions derived from sulfonic acids carrying long chain alkyl groups as disclosed in J.P. KOKAI Nos. Sho 58209733, ho 62- 175731 and Sho 63-262643.

The amount of the light-sensitiverdiazo compounds in the light-sensitive layer usually ranges from 5 to 50% by weight - and preferably 8 to 20%.by weight on the basis of the total weight of the light-sensitive layer.

The light-sensitive diazo compounds used in the invention are preferably used in combination with alkaline water-soluble or swellable lipophilic polymer materials as binders. Examples of such lipophilic polymeric compounds are the same copolymers listed above in connection with the positive-working lightsensitive compositions, having repeating units derived from the monomers (1) to (13) and molecular weights generally ranging from 10,000 to 200,000 as well as those having repeating units derived from the following monomers (14) and (15):

(14) unsatur ated imides such as maleimide, N-acryloyl(meth) acrylamide, N-acetyl(meth)acrylamide, N-propionyl(meth) 3 6 acrylamide and N-(p-chlorobenzoyl)(meth)acrylamide.

(15) unsaturated monomers having, on the side chains, crosslinkable groups such as N-[2-(acryloyloxy)ethyl]-2,3dimethylmaleimide, N-[2(methacryloyloxy)hexyl]-2,3dimethylmaleimide and vinyl cinnamate.

Further, other monomers copolymerizable with the foregoing monomers may be copolymerized. Moreover, the binders also include copolymers obtained through copolymerization of the foregoing monomers which are further modified with glycidyl (meth)acrylate. However, the present invention is not restricted to these specific binders.

1 The foregoing copolymers preferdbly comprises moieties derived from the unsaturated carboxylic acids (3) listed above and the acid value thereof preferably ranges from 0 to 10 meq/g and more preferably 0.2 to 5.0 meq/g.

Moreover, preferred molecular weight of these copolymers ranges from 10, 000 to 100,000.

The copolymers serving as binders in the light-sensitive composition may, if desired, comprise polyvinyl butyral, polyurethane, polyamide and/or epoxy resins. Other preferred binders are, for instance, novolak type resins, phenol-modified xylene resins, polyhydroxystyrene, halogenated polyhydroxystyrene and alkali-soluble resins having phenolic hydroxyl groups as disclosed in J.P. KOKAI No. Sho 51-34711.

These alkali-soluble polymers may be used alone or in combination and the amount thereof to be added to the light- 3 7 sensitive composition ranges from 40 to 95% by weight based on the total weight of the solid contents of the composition.

Examples of photocrosslinkable polymers used in the photocrosslinkable light-sensitive layer include those having groups such as maleimido, cinnamyl, cinnamoyl, cinnamylidene, cinnamylideneacetyl and/or chalkone groups in the main or side chains.

Examples of polymers having maleimido groups on the side chains are polymers represented by the following general 10 formula (I):

0 11 c -N / c R 2 11 0 R' - (1) (wherein RI and R2 each independently represents an alkyl group having at most 4 carbon atoms or R1 and R2 may form.a 5- or 6membered carbon ring together with the carbon atoms to which 20 they are bonded) such as those disclosed in J.P. KOKAI No. Sho 52-988 (= U.S. Patent No. 4,079,041), German Patent No. 2,626,769, European Patent Nos. 21,019 and 3,552 and Die Angewandte Makromolekulare Chemie, 1983, 115, pp. 162-182; and polymers represented by the following general formula (II):

3 8 0 11 -N c R 3 C R' 11 0 1 (wherein R3 represents an aromatic group and R4 represents a hydrogen atom, a halogen atom, an alkyl group or a cyano group) such as those disclosed in J.P. KOKAI Nos. Sho 49-128991, Sho 49-128992, Sho 49-128993, Sho 50-5376, Sho 50-5377, Sho 505378, Sho 50-5379, Sho 50-5380, Sho 53- 5298, Sho 53-5299, Sho 53-5300, Sho 50-50197, Sho 51-47940, Sho 52-13907, Sho 50-45076, Sho -52-121700, Sho 50-10884 and Sho 50-45087 and German Patent Nos. 2,349,948 and 2,616,276. The-average-molecular weight of these polymers is not less than 1,000 and preferably 30,000 to 40,000. Moreover, these polymers each has at least two maleimido groups per molecule on the average.

Acidic groups may be incorporated into these polymers having maleimido groups to make them alkaline water-soluble or swellable.

Specific examples of such acidic groups are tho se derived from carboxylic acids, sulfonic acids, phosphoric acids, phosphonic acids and alkali metal salts and ammonium salts thereof as well as acidic groups havingdissociation constant pKa with respect to alkaline water ranging from 6 to 12 such as -S02NHCO-, -CONHCO-, -S02NHCOO- and 4-hydroxyphenyl group- The polymers usable in the present invention can esily be prepared by copolymerizing monomers having these acidic groups and 3 9 monomers having maleimido groups in a molar ratio ranging from 10/90 to 50/50 and preferably 20/80 to 40/60. The acid value of the maleimide polymer having acidic groups preferably ranges from 30 to 300 and more preferably 50 to 200. In this respect, examples of the foregoing monomers having acidic groups preferably used herein include vinyl monomers having carboxyl groups such as (meth)acrylic acid, maleic anhydride and itaconic anhydride.

Useful examples of the polymers having acidic values falling within the range defined above are.copolymers of N[2methAcryloyloxy)ethyl]-2,3-dimethylmaleimide with (meth)acrylic acid such as those disclosed in Die fingewandte Makromolekulare Chemie, 1984, 128, pp. 71-91. Moreover, multicomponent polymers may easily be synthesized, depending on purposes, by carrying out the foregoing copolymerization in the presence of a third vinyl monomer. For instance, flexibility can be imparted to the foregoing copolymer through the use of alkyl (meth)acrylate whose homopolymer has a glass transition temperature of not more than room temperature as the third vinyl monomer component. Among other photocrosslinkable polymers having, in the main and/or side chains, cinnamyl, cinnamoyl, cinnamylidene, cinnamylideneacetyl and/or chalkone groups, those having lightsensitive cinnamoylene groups in the main chains include, for instance, light-sensitive polyesters as disclosed in U.S. 25 Patent No. 3, 030,208 and U.S. Patent Application Serial Nos. 709,496 and 828,455. The polyesters are prepared by condensing 1 4 0 appropriate polycarboxylic acids or lower alkyl esters or -chlorides of appropriate polycarboxylic acids with appropriate polyhydric alcohols in the presence of an esterification catalyst.

Examples of these polymers which are made alkali-soluble are as follows:

Light-sensitive polymers prepared by reacting polyester prepolymers having, in the main chains, photodim.erizable unsaturated double bonds in the proximity to an aromatic nucleus and carrying carboxyl groups, on the side chains, and terminal. hydroxyl groups with chain extenders each having at least two functional groups reactive with hydroxyl group such as diisocyanate compounds, diphenyl terephthalate, diphenyl carbonate, terephthaloylbis(N- caprolactam) as disclosed in J.P.

KOKAI No. Sho 60-191244; and light-sensitive polymers prepared by reacting polyester prepolymers or polyurethane polymers having photodimerizable unsaturated double bonds in the main chain in the proximity to an aromatic nucleus and terminal hydroxyl groups with chain extenders such as pyromellitic anhydride or cyclopentane tetracarboxylic dianhydride to thus incorporate carboxyl groups in the side chains of the resulting polymers; and Alkali-soluble or swellable light-sensitive polymers having, on the side chains, photodimerizable functional groups and carboxyl groups and having an acid value ranging from 20 to 200.

4 1 These light-sensitive polymers are disclosed in, for instance, J.P. KOKAI Nos. Sho 62-175729, Sho 62-175730, Sho 63 25443, Sho 63-218944 and Sho 63-218945.

The molecular weight of the photocrosslinkable polymer suitably used in the invention is not less than 1,000, preferably 10,000 to 500,000 and more preferably 20,000 to 300,000.

The amount of the photocrosslinkable polymer to.be added to the light-sensitive composition ranges from 10 to 99% by weight and preferably 50 to 99% by weight on the basis of the total weght of the composition.

The light-sensitive layer.comprising a photocrosslinkable polymer preferably include a light-sensitive diazo resin for improving the adhesion thereof to a substrate. Examples of such diazo resins are those listed above.

The diazo resin is added to the-light-sensitive layer in an amount ranging from 0.1 to 30% by weight and preferably 1 to 10% by weight on the basis of the weight of the light-sensitive layer.

The diazo resins disclosed in, for instance, J.P. KOKOW Nos. Sho 47-1167 and Sho 52-7364 and J.P. KOKAI Nos. Sho 50 118802 and Sho 59-222834 may be used in combination with the foregoing diazo resins in an amount of not more than 50% by weight with respect to the latter.

4 2 The light-sensitive layer used in the invention may comprise a sensitizer. Preferred such sensitizers are triplet sensitizers having a maximum absorption such that it practically permits sufficient absorption of light at a wavelength of not less than 300 nm.

Sensitizers of this type are, for instance, benzophenone derivativesi benzanthrone derivatives, quinones, aromatic nitro compounds, naphthothiazoline derivatives, benzothiazoline derivatives, thioxanthones, naphthothiazole derivatives, ketocoumarin compounds, benzothiazole derivatives, naphthofuranone compounds, pyrylium salts and thiapyrylium salts. Specific examples thereof are Michler's ketones, N,Nldiethylaminobenzophenone, benzanthrone, (3-methyl-1,3-diaza1,9-benz)anthrone picramide, 5-nitroacenaphthene, 2chlorothioxanthone, 2-isopropylthioxanthone, di methylthioxanthone, methylthioxanthone-l-ethylearboxylate, 2nitrofluorene, 2dibenzoylmethylene-3-methylnaphthothiazoline, 3,,3-carbonyl-bis(7diethylaminocoumarin)., 2,4,6triphenylthiapyrylium perchlorate and 2-(pchlorobenzoyl) naphthothiazole. These sensitizers may be added to the lightsensitive layer in an amount preferably ranging from about 1 to about 20% by weight and more preferably 3 to 10% by weight on the basis of the total weight of the light-sensitive layer.

The foregoing various negative-working light-sensitive compositions may preferably comprise a sensitizing agent for enhancing the ink receptivity of images (such as a half ester of 4 3 styrene/maleic anhydride copolymer with an alcohol, novolak resin or 50% fatty acid ester of p-hydroxystyrene as disclosed in J.P. KOKAI No. Sho 55-527).

In addition, the compositions preferably comprise plasticizers for imparting flexibility and wear resistance to the resulting coated film. Examples of such plasticizers are butyl phthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl ph thalate,.dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate and oligomers and polymers of (ineth)acrylate, with tricresyl phosphate being particularly preferred.

The negative-working light-sensitive composition used in the invention may comprise, for the improvement of its ' stability with time, additives such as phosphoric acid, pbosphonic acid, citric acid, oxalic-acid, dipicolinic acid, benzenesulfonic acid, naphthalenesulfonic acid, sulfosalicylic acid, 4- methoxy-2-hydroxybenzophenone-5-sulfonic acid and tartaric acid. 20 The negative-working light-sensitive composition used in the invention may comprise printing out agent for obtaining a visible image immediately after imagewise exposure to light and/or dyestuffs serving as agents for coloring images such as dyes or pigments. The dyestuffs are preferably those which change color tone through the reaction with free radicals or acids. Specific 4 4 examples thereof which are initially colored and converted into colorless ones, or which cause color change are triphenylmethane, diphenylmethane, oxazine, xanthene, iminonaphthoquinone, azomethine or anthraquinone type dyes.

On the other hand, examples of dyestuffs which are initially colorless and converted into colored ones are leuco dyes and primary and secondary arylamine type dyes.

Particularly preferred dyestuffs are triphenylmethane and diphenylmethane type ones, with triphenylmethane type dyestuffs being more preferred and Victoria Pure Blue BOH being particul4rly preferred.

The foregoing dyestuffs are in gefieral used in the lightsensitive composition in an amount ranging from about 0.5 to 10% by weight and preferably about 1 to 5% by weight on the basis of the total weight of the composition- The negative-working light-sensitive composition used in the invention may comprise cyclic acid anhydrides, phenols, organic acids and/or higher alcohols, whose specific examples are identical to those listed above in connection with the positive-working PS plates.

The negative-working light-sensitive composition is dissolved in a solvent in which the foregoing components are soluble and then applied onto an aluminum plate serving as a substrate. Examples of such solvents used herein are preferably organic solvents as disclosed in, for instance, J.P. KOKAI No. Sho 62-251739 which may be used alone or in combination.

4 5 7-- The negative-working light-sensitive composition is dissolved or dispersed in the solvent in a concentration ranging from 2 to 50% by weight (solid content), applied to an aluminum. substrate and then dried.

The coated amount of the layer of the negative-working light-sensitive composition (1 ight-sensitive layer) applied onto the substrate varies depending on the applications of the resulting plates, but preferably ranges from 0.3 to.4.0 g/m2 (weighed after drying). As the coated amount decreases, the quantity of light required for imagewise exposure is reduced and the trength of the resulting film is also lowered. On the other hand, as it is increased, the qudntity of light required for imagewise exposure is increased and the strength of the resulting film-is likewise in creased and if the resulting light- sensitive material is used as a PS plate, it can provide a lithographic printing plate capable of providing a large number of acceptable copies (i.e., having high printing durability).

The negativeworking light-sensitive composition may comprise a surfactant for improving the coating properties thereof, like the positive-working light-sensitive composition already discussed above.

When a PS plate is prepared, the back coat layer to be applied onto the back face of the substrate may be formed prior to the formation of the light-sensitive layer on the surface thereof, or vice versa, or they can simultaneously be applied to both sides of the substrate.

4 6 M 1 [Mat Layer] A mat layer is preferably applied onto the surface of the light-sensitive layer thus formed to reduce the time required for evacuation during contact exposure using a vacuum printing frame and to prevent the formation of an indistinct image during printing. Examples of such mat layers are disclosed in J.P. KOKAI No. Sho 50- 125805 and J.P. KOKOKU Nos. Sho 57-6582 and Sho 61-28986. Alternatively, the mat layer can also be formed by fusing, with heating, solid particles onto. the surface of the light-sensitive layer as disclosed in J.P. KOKOKU No. Sho 62-62337, with PS plates having water-soluble and alkaline water-developable mat layers being more-preferred.

[Development Processing] The PS plate thus prepared is imagewise6x posed, through an original transparency, to actinic-light rays from a light source such as a carbon arc lamp, a mercury lamp, a metal halide lamp, a xenon lamp or a tungsten lamp, and then developed.

The developer and replenisher of the present invention are useful in particular in a developing method which makes use of an automatic developing machine and in which a reduction in the activity of the developer used is preferably compensated through the addition of a replenisher. The replenisher can be supplemented by a known technique such as a method for compensating the deterioration of the developing ability of a developer due to processing of PS plates and the lapse of time 4 7 through continuous or intermittent supplementation as disclosed in J.P. KOKAI No. Sho 55-115039; a method comprising detecting the degree of dissolution of light-sensitive layer in the course of a developing zone and supplementing a replenisher in proportion to the reduction of the detected dissolution degree as disclosed in J.P. KOKAI No. Sho 58-95349; a method comprising determining impedance values of a developer, processing the values with a computer and supplementing a replenisher in proportion to the detected degree of deterioration of the developer as disclosed in J.P. KOKAI Nos. Hei 1-21451 and Hei 1-180548:

The PS plate developed in the fobegoing manner is posttreated with a rinsing solution comprising, for instance, a surfactant and/or a desensitizing Sum solution containing, for instance, gum arabic and/or starch derivatives. The prosttreatment of the PS plate herein.used may comprise any combination of these treatments.

Recently, there have been used automatic developing machines in the development of PS plates for the purpose of rationalization and standardization of the plate-making operations in the fields of plate-making and printing industries. The automatic developing machines of this type generally comprises a developing zone and a post- treatment zone and more specifically, it comprises a device for conveying PS plates to be processed, baths filled with various processing solutions respectively and spray devices, wherein an imagewise 4 8 v exposed PS plate is developed by spraying each processing solution, sent up by a pump, thereon through a spray nozzle while the PS plate is horizontally conveyed. Alternatively, there has recently been known a method in which an imagewise exposed PS plate is developed by conveying the plate while dipping it in a bath filled with a processing solution through the action of submerged guide rolls. In such an automatic processing, the PS plate can be processed while supplementing replenishers to the corresponding processing baths in proportion to the amount of the processed PS plates and the operation time.

15.

The developer of the present invention can also be used in a so-called batchwise processing system wherein PS plates are processed in a substantially fresh processing solution.

The lithographic printing plate produced through the processing described above is fitted to an offset printing press to form a large number of copies.

The developer and replenisher of the present invention are excellent in developing stability, storage stability and developing ability, has low foaming properties and can be used in the common processing of negativeand positive-working PS plates.

The present invention will hereinafter be explained in more detail with reference to the following non-limitative working Examples and the effects practically attained by the present invention will also be discussed in detail in 4 9 comparison with Comparative Examples.

Example 1

An aluminum plate having a thickness of 0.30 mm was subjected to a graining treatment with a nylon brush and an aqueous suspension of 400 mesh pumice stone and then sufficiently washed with water. The plate was then etched by immersing in a 10% sodium hydroxide solution at 70C for 60 seconds followed by washing with running water, neutralization and washing with a 20% HN03 solution and water-washing. Then the platq was electrolytically surface-roughened in a 1% aqueous solution of nitric acid at the quantity of electricity at the anode time of 160 coulomb/dM2 and VA Of 12.7 V using a sinusoidal alternating waved current. At this stage, the surface roughness thereof was determined and found to be 0.6 g (expressed in terms of Ra unit). Then it was desmutted by immersing in a 30% H2SO4 at 550C for 2 minutes and then anodized in a 20% aqueous solution of sulfuric acid at a current density of 2 A/dM2 so that the thickness of the resulting anodized layer was 2.7 g/m2 while a cathode was fitted to the grained surface of the aluminum plate to give a substrate. In this respect, an anodized layer was likewise formed on the back face of the aluminum plate in a thickness of about 0.2 g/M2 at the central portion and about 0.5 g/M2 at the edge portion.

A back coat layer was formed on the baqk face of the substrate thus treated by applying a sol-gel reaction solution 0 detailed below with a bar coater in an amount (weighed after drying) of 50 Mg/M2 and then drying at 100 OC f or one minute to give a substrate having the back coat layer.

Sol-Gel Reaction Solution Component tetraethylsilicate water methanol nitric acid Amount (part by weight) so 21.6 10.8 0.05 When the foregoing components were mixed and stirred, the mixture generated heat within about 5 minutes.. After reacting the components for 10 minutes, 700 parts by weight of methanol was added to the mixture to give a coating solution for forming back coat.

Thereafter, the following light-sensitive solution I was applied onto the surface of the aluminum substrate so that the coated amount of the solution (weighed after drying) was equal to 2.5 g/m2 and then dried to form a light-sensitive layer.

Light-Sensitive Solution I Component Amount (part by weight) ester of 1,2-diazonaphthoquinone-5-sulfony1 chloride 45 with pyrogallol/acetone resin (product disclosed in Example 1 of U.S. Patent No. 3,635,709) 1 cresol/formaldehyde novolak resin 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s- triazine Oil Blue #603 (available from Orient Chemical Industry Co., Ltd.) Megafac F-177 (a fluorine atom-containing surfactant 0.4 available from Dainippon Ink & Chemicals, Inc.) methyl ethyl ketone propylene glycol monomethyl ether 1 1000 1000 2 A piat layer was applied onto the light-sensitive layer thus formed by spraying a mat layer-forming resin solution thereon to thus give a PS plate provided with a mat layer.

A 12% aqueous solution of methyl methacrylate/ethyl acrylate/acrylic acid (charge weight ratio:-.65/20/15) copolymer, which was partially converted into sodium salt, was prepared as the mat layer-forming resin solution, applied onto the lightsensitive layer with a rotary atomizationelectrostatic coating machine at a atomization head-rotation number of 25, 000 rpm, a 20' resin solution-feed rate of 40 ml/min, a voltage applied to the atomization head of -90 KV, at an environmental temperature during coating of 25 OC and a relative humidity of 50% and, 2.5 seconds after the coating, the coated layer was swollen by spraying steam on the coated surface and 3 seconds after the swelling, the layer was dried by blowing, for 5 seconds, hot air having a temperature of 600C and a humidity of 10% thereon.

2 The height of the projections of the mat layer was about 6 g m and the diameter thereof was about 30 g m on the average. The coated amount of the mat layer was 150 Mg/M2.

The PS plate thus prepared was cut to prepare a large number of sheets each having a size of 1, 003 mm X 800 mm and each sheet was imagewise exposed to light from a 3 KW metal halide lamp at a distance of 1 m through an original film for seconds. - Then concentrated stock solutions of a developer 1 and a replenisher 1 each having the following composition were prepared,.. These concentrated stock solutions did not become turbid or cause any separation even after an incubation test performed at 600C for one month.

Stock Solution for Developer 1 Component Amount (part by weight) aqueous solution of potassium silicate having a 1000 molar ratio: [Si021/[K201 of 1.2 and an Si02 content of 12.2% by weight polyoxyethylene (molar number of added ethylene oxide: n = 12) sorbitol Stock Solution for Replenisher 1 Component Amount (part by weight) aqueous solution of potassium silicate having a 1000 molar ratio: [Si021/[K201 of 0.8 and an Si02 3 content of 11.4% by weight polyoxyethylene (molar number of added ethylene oxide: n = 12) sorbitol 4 A commercially available automatic developing machine, PS90ONP (Fuji Photo Film Co., Ltd.), equipped with a dip type developing bath was used for developing the foregoing imagewise exposed PS plates. The foregoing stock solution for developer 1 was diluted 9 times with tap water to give 22 9 of a developer practically used and introduced into the developing tank of the machlne.. Separately, a tank for supplying the stock solution for replenisher was charged with 5 9 of the stock solution for replenisher 1. Under these conditions, the foregoing imagewise exposed PS plates were successively processed in a rate of 100 sheets per day over one month. Incidentally, the reduction in the activity of the developer due to the processing of the PS plates and absorption of carbon dioxide in the air during the foregoing successive processing was detected by a built-in conductivity sensor of the machine, PS-90ONP, and the activity thereof was kept constant by supplementing the stock solution for replenisher 1 and water in a ratio of 1:5 according to a feedback system under the control of a computer. The activity of the developer was determined by exposing the foregoing PS plate to light through a step tablet (comprising 15 steps having a density difference of 0.15) while stepwise changing the quantity of light, developing the PS plate, reading the number of step 4 0 0, 0 1 which carried images in proportion to the quantity of light irradiated and comparing the number of step with that observed when the processing was initiated.

The step number of the solid portion (portion which carried images) of the step tablet was kept at 11 throughout the test over one month, the developing bath was not contaminated due to foaming and stable processing could be ensured. In addition, the amount of the replenisher supplemented was low on the order of 43 Ml/M2 on the average and there was not observed any deposition of insoluble matter on the bottom of the devdlopi.ng bath when the developer was withdrawn therefrom after the completion of the test.

Example 2

The same procedures used in Example 1 were repeated except that the following developer 2 and replenisher 2 were used instead of the developer 1 and the replenisher 1.

Stock Solution for Developer 2 Component Amount (part by weight) aqueous solution of potassium silicate having a 1000 molar ratio: [Si02]/[K201 of 1.4 and an SiO2 content of 14.4% by weight polyoxyethylene (molar number of added ethylene oxide: n = 10) diglycerin 5 Stock Solution for Replenisher 2 Component Amount (part by weight) aqueous solution of potassium silicate having a 1000 molar ratio: [Si02]/[K201 of 1.1 and an Si02 content of 12.5% by weight polyoxyethylene (molar number of added ethylene oxide: n = 10) diglycerin The concentrated stock solutions did not become turbid or cause any separation even after the incubation test identical to that used in Example 1. The step number of the solid portion of the step tablet was kept at 11 throughout the test over one month, the developing bath did not cause foaming and stable processing could be ensured.

In addition, the amount of the replenisher supplemented was low on the order of 45 Ml/M2 on the average. There was not observed any deposition on the bottom of the developing bath when the developer was withdrawn therefrom after the-completion of the test.

Comparative Example 1 The same procedures used in Example 1 were repeated except that polyoxyethylene (molar number of added ethylene oxide: n = 12) sorbitol was not added to the stock solution for 25 replenisher and it was found that the step number of the solid portion of the step tablet was kept at 11 upon initiation of 6 1 the processing, but it was gradually increased up to 13.5 which was observed after one month and there were observed narrowing of finelines and formation of indistinct images.

Comparative Example 2 In the stock solution for replenisher used in Example 1, one part by weight of polyoxyethylene/polyoxypropylene block copolymerized surfactant (Pluronik P-85 available from Asahi Denka Kogyo KK) was substituted for the polyoxyethylene (molar 10 number of added ethylene oxide: n = 12) sorbitol, but the surfactant was not completely dissolved and a part thereof floated on the surface in the form of oill balls.

Therefore, concentrated stock solutions of developer and replenisher were not prepared and developer and replenisher 15 were prepared in concentrations practically used. The same procedures used in Example 1 were repeated except for the preparation of the developer and replenisher. As a result, it was found that the step number of the solid portion on the step tablet was kept at 11 upon initiation of the processing, but it 20 gradually decreased down to 9 after one month and film edges and finelines were expanded during printing operations.

Example 3

An aluminum plate having a thickness of 0.2 mm was subjected to a graining treatment with a nylon brush and an aqueous suspension of 400 mesh pumice stone and then 7 sufficiently washed with water. The plate was then etched by immersing in a 10% sodium hydroxide solution at 70 OC for 60 seconds followed by washing with running water and electrolytical surface-roughening in a 1% aqueous solution of nitric acid at the quantity of electricity at the anode time of 160 coulomb/dM2 and V A of 12.7 V using a sinusoidal alternating waved current. Then it was desmutted by immersing in a 30% H2S04 at 550C for 2 minutes and then anodized.in a 20% aqueous sulfuric acid solution at a current density of 2 A/dM2 so that the thickness of the resulting anodized layer was 1.5 g/M2 ani thereafter, hydrophilized in an aqueous solution of No. 3 sodium silicate at 70 OC.

Thereafter, the following light-sensitive solution II was applied onto the surface of the aluminum substrate so that the coated amount of the solution (weighed after drying) was equal to 1.5 g/m2 and then dried at 800C for 2 minutes to form a negative-working PS plate.

Light-Sensitive Solution II Component Amount (part by weight) methyl methaerylate/N-[6- (methacryloyloxy)hexyl]-2,3- 5 dimethylmaleimide/methacrylic acid (molar ratio=10/ 60/30) copolymer [Mw=3.5 x 1011 (GPC); TS = about 400C (DSC)] 3-ethoxycarbonyl-7-methyl-thioxanthone 0.25 dodecylbenzenesulfonate of co-condensate of 4-diazo- 0.20 8 diphenylamine, phenoxyacetic acid and formaldehyde propylene glycol monomethyl ether methyl ethyl ketone Megafac F-177 (a fluorine atom- containing surfactant available from Dainippon Ink & Chemicals, Inc.) Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd.) 50 0.03 0.10 The PS plate thus prepared was cut to prepare a large number of sheets each having a size of 1,003 mm x 800 mm and each sheet was imagewise exposed to light from a 3 KW metal halide lgmp at a distance of 1 m through an original film for 40 seconds. Then these imagewise expo:ged negative-working PS plates were processed in common with the positive-working PS plates prepared in Example 1 using the same automatic developing machine and conditions for development used in Example 1. In this respect, the negative-working and positiveworking PS plates were alternatively processed. The sum of the positive- and negative-working PS plates thus processed was 100 sheets. As a result, it was found that the negative-working PS plates were satisfactorily developed and the number of the solid portion on the positive-working PS plate was kept at 11. In addition, the amount of the replenisher supplemented was 40 M1/M2 on the average and there was not observed any deposition of insoluble matter on the bottom of the developing bath after the completion of the test.

9 Comparative Example 3 The same procedures used in Example 3 were repeated except that polyoxyethylene (molar number of added ethylene oxide: n = 12) sorbitol was not added to the stock solution for replenisher. As a result, it was found that the negative-working PS plates could be processed at the initial stage of the processing, but the developability was gradually reduced and after one month, the negative-working PS plates were found to be insufficiently developed.

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Claims (12)

Claims

1. A developer for presensitized plates for use in making lithographic printing plates comprising an alkali metal silicate having a molar ratio: Si02/M20 (wherein M represents an alkali metal) ranging from 0.5 to 2.0 and a water-soluble ethylene oxide adduct obtained by adding not more than 5 moles of ethylene oxide to a sugar alcohol having not less than 4 hydroxyl groups.

2. The developer of claim 1 wherein the alkali metal silicate 10 is selected from the group consisting of sodium silicate, potdssiu,.m silicate, lithium silicate and mixture thereof and the concentration of the alkali metal silicate in the developer ranges from 1 to 10% by weight on the basis of the weight of the developer.

3. The developer of claim 1 wherein the sugar alcohol is selected from the group consisting of D, L-threitol, erythritol, D, L-arabitol, ribitol, xylitol, D, L-sorbitol, D, L-mannitol, D, L-iditol, D, L-talitol, dulcitol, allosulcite and di, tri, tetra, penta and hexa-glycerin obtained through condensation of sugar alcohols; and the water-soluble ethylene oxide adduct has a molar number of added ethylene oxide ranging from 5 to 50.

4. The developer of claim 1 wherein the amount of the watersoluble ethylene oxide adduct added to the developer ranges from 0.001 to 5% by weight on the basis of the weight of the developer practically used.

5. The developer of claim 1 wherein it further comprises at 6 1 least one alkaline agent other than the alkali metal silicate selected from the group consisting of sodium tertiary phosphate, potassium tertiary phosphate, ammonium tertiary phosphate, sodium secondary phosphate, potassium secondary phosphate, ammonium secondary phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium borate, potassium borate, ammonium borate, sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolmine, diethanolmine, triethanolmine, mPnoisopropanolamine, diisopropanolamine, ethyleneimine,- ethylenediamine and pyridine..

6. A development replenisher for presensitized plates for use in making lithographic printing plates comprising an alkali metal silica te having a molar ratio: Si02/M20 (wherein M represents an alkali metal) ranging from 0.3 to 1.5 and a water- soluble ethylene oxide adduct obtained by adding not more than 5 moles of ethylene oxide to a sugar alcohol having not less than 4 hydroxyl groups.

7. The development replenisher of claim 6 wherein the alkali metal silicate is selected from the group consisting of sodium silicate, potassium silicate, lithium silicate and mixture thereof and the concentration of the alkali metal silicate in 6 2 1 0 the developer ranges from 1 to 10% by weight on the basis of the weight of the developer.

8. The development replenisher of claim 6 wherein the sugar alcohol is selected from the group consisting of D, L-threitol, erythritol, D, Larabitol, ribitol, xylitol, D, L-sorbitol, D, L-mannitol, D, L-iditol, D, L-talitol, dulcitol, allosulcite and di, tri, tetra, penta and hexaglycerin obtained through condensation of sugar alcohols; and the watersoluble ethylene oxide adduct has a molar number of added ethylene oxide ranging from 5 to 50.

9. The development replenisher of claim 6 wherein the amount of the watersoluble ethylene oxidd adduct added to the developer ranges from 0.001 to 5% by weight on the basis of the weight of the developer practically used.

10. The development replenisher of claim 6 wherein it further comprises at least one alkaline agent other than the alkali metal silicate selected from the group consisting of sodium tertiary phosphate, potassium tertiary phosphate, ammonium tertiary phosphate, sodium secondary phosphate, potassium secondary phosphate, ammonium secondary phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium borate, potassium borate, ammonium borate, sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, 6 3 diisopropylamine, triisopropylamine, n-butylamine, monoethanolmine, diethanolmine, triethanolmine, monoisopropanolamine, diisopropanolamine, ethyleneimine, ethylenediamine and pyridine.

11. A developer for presensitised plates for use in making lithographic printing plate substantially as herein described with reference to any one of the accompanying Examples.

12. A development replenisher for presensitised plates for use in making lithographic printing plates substantially as herein described with reference to any one of the accompanying Examples.

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