GB2192729A

GB2192729A - A presensitized printing plate precursor

Info

Publication number: GB2192729A
Application number: GB08713700A
Authority: GB
Inventors: Keiji Akiyama; Akira Nishioka; Akira Nagashima; Nobuyuki Kita
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1986-06-12
Filing date: 1987-06-11
Publication date: 1988-01-20
Also published as: DE3719684A1; DE3719684C2; GB2192729B; GB8713700D0; JPS62293247A; JPH065384B2

Description

GB2192729A 1

SPECIFICATION

Presensitized printing plate precursor FIELD OF THE INVENTION 5

This invention relates to a presensitized printing plate precursor, and more particularly a presep sitized printing-plate Or ecursor having a positively working photosensitive layer containing an improved dye.

BACKGROUND OF THE INVENTION 10

It is known that a print-out effect can be imparted to a photosolubilizable composition com prising, an -o-quinonediazide compound and a novolak resin by incorporating a compound capable of producing an acidic substance upon photolysis by exposure to light and an organic dye which changes its hue through mutual interaction with the photolysis product of the aforesaid corn pound. For example, the so far proposed compounds capable of producing an acidic substance 15 upon photolysis include o-naphthoquinonediazide-4-suifonyI halogenides as disclosed in Japanese Patent Application (OPI) No. 36209/75 (the term---OPI-as used herein means -unexamined - published application-); tri.halomethyi-2-pyrones and trihalomethyltriazines as disclosed in Japa nese Patent Application (OPI) No. 36223/78; various onaphthoquinonediazide compounds as disclosed in Japanese Patent Application (OPI) No. 62444/80; and 2- trihalomethyl-5-ary]-1,3,4oxadiazole compounds as disclosed in Japanese Patent Application (OPI) No. 77742/80.

The conventional organic dyes which change their hues by mutual interaction with the photo lysis products of the above-described compounds include diphenylmethane dues, triaryimethane dyes, thiazine dyes, oxazine dyes, phenazine dyes, xanthene dyes, anthraquinone dyes, iminonaphthoquinone dyes, and azomethine dyes. 25 Specific examples of these organic dyes are Brilliant Green, Eosine, Ethyl Violet, Erythrosine B, Methyl Green,, Crystal Violet, Basic Fuchsine, phenol phthalein, 1,3diphenyltriazine, Alizarin Red S, Thymolphthalein, Methyl Violet 2B, Quinaldine Red, Rose Bengale, Metanil Yellow, Thymolsulfo phthaiein, Xylenol Blue, Methyl Orange, Orange W, diphenyl thiocarbazone, 2,7-dichlorofluores cein, Paramethyl Red, Congo Red, Benzopurpurine 4B, aNaphthyl Red, Nile Blue 2B, Nile Blue A, 30 Phenacetalin, Methyl Violet, Malachite Green, p-Fuchsine; Oil Blue #603, Oil Pink #312, Oil Red 5B, Oil Scarlet #308, Oil Red OG, Oil Red RR, and Oil Green #502 (all produced by Orient C emical Co., Ltd.); Spiron Red BEH Special and Victoria Pure Blue BOH (both produced by Hodogaya Chemical Co., Ltd.);-Patent Pure Blue, (produced by Sumitomo Mikuni Kagaku Kogyo K.K.); Sudan Blue 11 (produced by BASF A.G.); m-Cresol purple, Cresol Red, Rhodamine B, 35 Rhodamine 6G, First Acid Violet R, Sulforhodamine B, Auramine, 4-pdiethylaminophenyliminona phthoquinone, 2-carboxyanilino-4-p-d iethylaminophenyl iminona phthoqui none, 2-carbostearylamino 4-p-di-hydroxyethylaminophenyliminonaphthoquinone, p-methoxy-benzoyl-p'diethylamino-o'-me- - thylphenyliminoacetanilide, cyano-p-diethylamino-phenyliminoacetanilide, 1-phenyi-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1,6-naphthyi-4-pdiethylaminophenylimino-5-pyrazolone, etc. 40 Many water-soluble basic dyes are advantageous for use in the above- described presensitized printing plate precursors in that they show a high color formation efficiency in a photosensitive layer (density in image areas before exposure to light) with a small amount, and also they have satisfactory print-out properties after exposure, i.e., a great difference in density between ex- posed areas and non-exoosed areas. Among the basic dyes, triaryimethane dyes are particularly 45 effective.

However, since almost all of the conventional basic dyes use a chlorine ion as a counter anion, they do not have sufficient solubility in organic solvents so that much time is required for dissolving such dyes in an organic solvent to be used for coating and this is still insufficient for complete dissolution. Basic dyes using oxalic acid or sulfuric acid as a counter anion source are 50 also known. However, when they are applied to a positive_ photosensitive layer of a presensi tized printing plate, they are, likely to remain in non-i.m.age areas after development (hereinafter referred to as---color remaiffing-).

On the other hand, oil-soluble dyes exhibit high solubility in organic solvents. However, when they are developed with an alkaline aqueous solution, they form insoluble matter in, the developer 55 due to their oil solubility and this accelerates fatigue of the developer. Moreover, a presensitized printing plate precursor comprising a positive photosensitive layer containing the oil soluble dye has poor 'stability with time, reduced sensitivity or reduced print-out properties.

SUMMARY OF THE INVENTION 60

In the light of this prior art, there still remains a need in the art. for:

a presensitized printing plate precursor having a positively working photosensitive layer con taining basic dye which is excellent in solubility in organic solvents and can, therefore, be dissolved uniformly in an organic Solvent in a hort period of time for the preparation of a photoseositive coating composition. 65 2 GB2192729A 2 a positively working presensitized printing plqte- precursor providing a lithographic printing plate which is free from color remaining in- non-image areas; a positively working presensitized. printing plate precursor which forms no insoluble matter in a developer and exhibits satisfactory sensitivity and excellent stability with time.

-5 As a result of extensive investigations with a view to satisfying these needs, we have 5 developed a presensitized printing plate precursor comprising a grained and anodically oxidized aluminium-supporthaving provided thereon a positively working photosensitive layer containing a dye, wherein said dye is a salt formed between a basic dye cation and a counter anion, said counter anion being an organic anion having 8 or more carbon- atoms and one sulfonic acid' -group as a sole exchangeable group. 10 We have found that this printing plate precursor has advantageous properties which result,in improved performance in the problem areas identified above.

DETAILED DESCRIPTION OF THE INVENTION

The aluminum support which can be used in the present invention is made of pure aluminum 15 or an aluminum alloy containing silicon, copper, manganese, magnesium, chromium, zinc, lead, - bismuth, nickel, etc. The aluminum alloy may further contain a small proportion of iron or titanium and neglectable amounts of other impurities.

If desired, before the aluminum plate is subjected to graining, it may be cleaned to remove oils 2Q on its surface and/or pretreated to expose an aluminum surface. The former can be effected by 20 using solvents, e.g. trichlene, or surface active agents, and the latter can generally be carried out by using an'alkaline etching --'agent, e.g., sodium hydroxide, potassium hydroxide, etc. - Graining tdchniques which can be applied to the present invention are classified into mechani cal graining, chemical graining brid electrochemical graining (so-called electrolytic etching). Me chanical graining can be performed by wire graining using a metal wire brush for su rface 25 scratching, ball graining- Using abrasive balls and an abrasive, brush graining using a nylon brush and an abrasive, and the like. In particular, brush graining is suitable for mass production. For details of brush graining, reference can be made to it,'e.g., in U.S. Patent 3,891,516 and Japanese P - atent Publication No. 40047/75.

Chemical graining is suitably carried out by dipping'in a saturated aqueous solution of an 30 aluminum salt of a mineral acid as described in Japanese Patnet Application (OPI) No.

31187/80.

Electrochemical graining, is preferably: carried out by electrolysis in an acidic electrolytic solution containing hydrochloric acid, nitric acid or a combination thereof using an alternating electric current. Of these graining techniques, a combined process of mechanical graining and electroche- 35 mical graining as described in Japanese Patent Application JOPI) No. 137993/80 is particularly preferred in view of strong adhesion attained between an ink-receptive image and the support.

Graining of the aluminum plate is preferably effected so as to obtain a center-line-average roughness (Ra) of from 0.3 to 1.0 'Um.

The thus grained aluminum plate is then washed with water and, -if desired, subjected. to 40 chemical etching.

The etching solution is usually selected from an aqueous solutibri-of a base or an acid capable of dissolving aluminum., Specific examples of such an etching solution are described in U.S.

Patent, 3,834,998 corresponding to Japanese Patent Publication 33444/76. The etching process ing is preferably conducted unti, I from 0.5 to 10 g/M2 of aluminum-is etched (dissolved) after 45 desmutting hereinafter described.

After washing with. water, the etched aluminum plate is usually subjected to desmutting treatment with an acid to remove the smut resu Ited from the etc hing processing. The acid to be used for desmutting treatment includes nitric acid, sulfuric-acid, phosphoric acid, chromic acid, hydrofluoric acid, bqrofluori6 acid, etc. 50 The thus treated aluminum plate is then subjected to anodic oxidation after, if desired, washing with water. Anodic oxidation is- carried'out by a conventionally employed -process. More specifically, a director alternating current is applied to.the aluminum plate in.an aqueous or non aqueous solution of. sulfuric acid, phosporic acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc. or a.-.combinatign of two or more 'thereof to thereby form an anodic 55 oxidization film on the aluminum surface.

Conditions.for anodic oxidatin vary depending on the type of I the electrolyte used, but are preferably frorn.1 to 80% by weight in electrolytic solution concentration; from 5 to 700C in temperature, frorri 0.5 to 60 A/dM2 in current density; from 1 to 100 V in voltage; and from 30 to 50 minutes in electrolysis time. 60 In particular, the anodic oxidation is preferably carried but according to a process of British Patent 1,412,768 in which sulfuric acid and a high current density are used or a process of U.S.

Patent,511,661 in which phosphoric acid is used as an electrolyte.

If des'tred, the grained and anodically oxidized aluminum plate may further be subjected to surface treatment to render its surface hydrophilic. Such a treatment can be effected with an 65 3 GB2192729A 3 aqueous solution of an alkali metal silicate, e.g., sodium silicate, as disclosed in U.S. Patents 2,714,066 and 3,181,461, a potassium fluorozirconate aqueous solution as disclosed in U.S.

Patent 2,946,683 corresponding to Japanese Patent Publication 22036/61 or a polyvinylphos phonic acid aqueous solution as disclosed in U.S. Patent 4,153,461. In addition, the process disclosed in Unexamined published European Patent Application 149490 is also preferred for 5 rendering hydrophilic, in which an aluminum plate is treated with a solution of a compound baving an amino group and a carboxyl group, a sulfo group and/or a hydroxyl group.

On the thus prepared aluminum support may be provided, if desired, a photo-insensitive layer containing gum arabic, carboxymethyl cellulose, carboxyethyl cellulose, carboxymethylhydroxye- z;l 10 thyl cellulose, alginic acid, polyacrylic acid, an acrylic acid derivative, a co-condensation product 10 of vinyl methyl ether and maleic anhydride, a copolymer of vinyl acetate and maleic anhydride, and salts thereof; water-soluble metal salts (e.g., zinc acetate), yellow dyes, amine saltsi and fine particles of silica or titanium dioxide, etc.

A positively working photosensitive composition is then coated on the thus prepared support.

The positively working photosensitive composition preferably includes (a) a composition com- 15 prising a compound capable of producing a strong acid upon irradiation of actinic rays and a compound which is cleaved by the action of an acid (e. g., a polymeric compound having an orthocarboxylic acid ester group, and silyl ether compounds described in Japanese Patent Application (OPI) No. 17345/81) and (b) a composition comprising an o-quinonediazide compound and a phenolic resin, with the latter composition being preferred. 20 The o-4ui6onediazide compound to be used in the present invention is a compound'having at least one o-quinonediazido group whose solubility in an alkali is increased upon irradiation of, - actinic rays. Such a compound may have a wide variety of structures. The details for such an o quinonediazide compounds are described in J. Kosar, Light-Sensitive Systems, 339-352, John Wiley & Sons, Inc. (1965), and specific examples given therein can be applied to the present- 25 invention. In particular, sulfonic acid esters or sulforiamides of o- quinonediazide obtained by reacting with. various aromatic polyhydroxyl compounds or amines are suitable.

Of the o-quinonediazide compounds employable in the present invention, an ester compound formed between benzoquinone-(1,2)-diazidesulfonyI chloride and polyhydroxyphenyl and an ester compound formed between n aphthoquinone-(1,2)diazidosulf6nyI chloride and a pyrogallol-acetone 30 resin are the most preferred. Other examples of preferred oquinonediazide compounds are esters formed between benzoquinone-(1,2)-diazido-4 or 5-sulfonyl chloride or napht hoquinone (1,2)-diazido-4 or 5-sulfonyl chloride and a phenol-formaldehyde resin as described in U.S. - Patents 3,046,120 and 3,188,210.

Additional useful o-quinonediazide compounds are reported, e.g., in Japanese Patent Applica7-- - 35 tion (OPI) Nos. 5303/72, 63802/73, 6803/73, 96575/73, 38701/74, and 13354173, Japanese Patent Publication Nos. 11222/66, 9610/70, 'and 17481/74, U.S. Patents 2, 797/213, 3,454,400, 3,544,323, 2,573,917, 3,674,495, and 3,185,825, British Patents 1,227,602, 1,251,345, 1,267,005, 1,329,888, and 1,330,932, and German Patent 854,890.

The phenolic resin -to be used in combination with the aforesaid oquinonediazide compounds' 40 includes a novolak resin and a'polyvinyl compound having a phenolic hydroxyl group. The novolak resin is obtained. by condensation of a phenol and a formaldehyde in the presence of an acidic catalyst or by modifying,such a condensate with xylener or mesitylene. Such a novolak resi. n typically includes a phenol-formaldehyde resin, a cresol- formaldehyde resin, a p-t-butylphenolformaldehyde resin, a pheno-l-.-modified xylene resinj and the like. 45 The polyvinyl compound having a phenolic hydroxyl group includes a polyhydroxystyrene polymer or a copolymer thereof and a halogenated polyhydroxystyrene polymer or a copolymer thereof.

The photosensitive composition usually contains from 10 to 50% by weight, and,preferably from 20 to 40% by weight of'the o-quinonediazide compound and from 45 to 796/o'by weight,' 50 and preferably from..50 to- 6.% by -weight, of the phenolic resin.

The positive photpsensitiVe composition which Pon be used in the present invention further contains -a salt formed between a cation having a basic dye skeleton and an organic anion.

having 8 or more carbon atorTis and only one sulfonic acid group as an exchange group In general, basic, dyes are, water-s oluble, dyes containing. no acid radical and are lately -called 55 cationic dyes because the dye moiety thereof becomes a cation- in an aqueous solution. The basic dyes have a structure wherein an amin o. group, in its broad sense, or a heterocyclic. - nitrogen forms a salt With an acid component, mostly a hydrochloride and, in some cases, a zinc chloride complex salt, sulfate or an oxalate. These salts have satisfactory water solubility but poor solubility in organic solvents. They are generally characteriz. edby higher color density and 60 clearer hue as compared with other kinds of dyes. From the structural viewpoint, various structures are included in the basic dyes,- with many of them belonging to triarylmothane dyes having -p structure of formula 4 GB2192729A 4 (D 5 xe wherein X- represents an anion, hereinafter the same, xanthene dyes having a structure of formula 10 IN 0 XE) 15 acridine dyes of formula X9 c C: 0 20 azine dyes having a structure of formula N D X e G,:i C" 1-1 -.

oxazine dyes having a structure of formula 30 N X e -o (nD thiazine dyes having a structure of formula.35 N - G,0)XE). - c ', ' ', - - 40 and cyanine dyes having a structure of formula Y Y1 CH=CH),-CH-C Xe 45 ):31 N N- I wherein Y and Y' each represents 0, S, Se, NH, etc.; and n represents 0 or an integer of from 1 and 2. 50 In addition, some of the basic dyes belong to methine dyes, polymethine dyes, anthraquinone dyes, and az. o dyes'. All Of these dye skeletons can be used in the present invention. The above illustrated basic dye skeletons are known perse and are described in detail, e.g., in Yuki Gosei Kagaku Kyokai (ed.) Senryo Binran and Color Index.

0 f these basic dyes, triaryImethane dyes are preferred, with those having a basic skeleton 55 represented by formulae (1) or (11) shown below being more preferred.

Formulae (1) and (11) are presented by GB2192729A 5 R \\ N - ON \ R5 R2 C__ R6 M R3 Nlol XG R / i4 110 10 I R I "'N-(:1\ I R2 15 R5 R C R 11\ X / N- - Xe 20 R4 I x X - wherein Rj, R2, R3, R4, R5, and R6 each represents a hydrogen atom, an alkyl group having from 25 1 to 3 carbon atoms, an aryl group or an aryl group substituted with an alkyl group, a halogen atom, a nitro group, etc.; and X represents an anion.

It has been found that organic solvent solubility of the water-soluble basic dyes can be improved by using a highly oleophilic organic carboxylic acid or organic sulfonic acid as a counter anion. 30 However, basic dyes having an organic carboxylic acid anion as a counter anion turned out to be inferior to the chlorine anion-containing dyes in terms of color sharpness in a dried coating -_ film and print-out properties after exposure to light. This inferiority is considered to arise from reduction in color forming efficiency of dyes due to weak acidity of the organic carboxylic acid counter anion. Further, printing plates produced by using these dyes are inferior to those -35 produced by using the chlorine counter anion-containing dyes because of color remaining in non image areas after development.

On the other hand, a coating film containing dyes having an organic sulfonic, acid group as a counter anion has a satisfactory color hue and produces a satisfactory print-out effect after light exposure because the counter anion has a higher acidity. Further, when the counter anion is a 40 compound having only one sulfonic acid group as an exchange group, it was confirmed that color remaining can be reduced as compared with the chlorine counter anion. The exchange group herein referred to means a group imparting a capability of undergoing ion-exchange reaction and includes a sulfonic acid group (-SO,H), a phosphono group (- PO,H2), a carboxyl group (-COOH), a phenolic hydroxyl group (-OH), a quaternary ammonium base (-NR3QH), a 45 sulfoniurn base (-SR20H), and various substituted ammonium bases (-NH,OH, -NH2ROH, and -NHR,OH, wherein R represents,an alkyl group, an aryl group, etc.

In general, as a dye has higher water solubility, it is less likely that the dye forms an insoluble matter when developed with a developer comprising an alkaline aqueous solution, and it is expected that a rate of development be increased and color remaining be reduced. According to 50 the present invention, since oil solubility is imparted to basic dyes aiming at improvement of solubility in organic solvents, it was anticipated that these dyes easily form insoluble matters to cause color remaining.. To the contrary, it has been surprisingly proved that the dyes wherein a compound having only one sulfonic acid group as an excahnge group is used as a counter anion do not dause formation of any insoluble matter at the time of development and rather reduce 55 color remainin, g when compared with dyes having a chlorine counter anion.

In cases where the counter anion contains not only one sulfonic acid group but also other exchange groups, and particularly a phenolic hydroxyl group or a carboxyl group, color remaining is remarkably recognized as compared with the, chlorine counter anion dyes. The color remaining is expressed by a difference obtained by subtracting a reflective optical density of an aluminum 60 support before forming a photosensitive layer from that of a non-image area on a lithographic printing plate after development (i.e., an exposed surface of a support).. The smaller the differ- ence irl optical density, the less the color remaining. The color remaining tends to 'increase particularly when development is effected with a developer fatigued from development of a large -65 quantity of presensitized printing plate precursors. The print-out properties can be expressed by 65 6 GB2192729A 6 a difference between a reflective optical density of a non-image area and that of an image area. The greater the difference,. the better.

It should be noted, however, that an organic anion having 7 or less carbon atoms even containing one sulfonic acid group, such as p- toluenesulfonic acid anion, is disadvantageous because a salt of such an anion with a basic dye cation becomes tar-like, which is difficult to 5 purify and also results in low yields. Therefore, the organic anion to be used in the present invention should have at least 8 carbon atoms.

The organic anion having 8 or more carbon atoms and containing only one sulfonic acid anion as an exchange group includes those derived from aromatic compoounds and those derived from aliphatic compounds. 10 Examples of the aromatic anions are shown below.

e CH20 03 15 Oe \\--CONH-I\ -S 3 20 3 OCOCH3 _e - S03<)Y 25 No 2 sojoa 30 e 35 e CH2CH-aS03 40 7 e CH3OCO7aSO3 45 (8) Anions derived from the following 'alkylarylsulfonates anionic surface active agents:

a) R-(/ \\/-so 3 Na 50 wherein R represents an alkyl group having from 2 to 16 carbon atoms b) R n - - 55 I Ar I so 3 Na wherein R represents an alkyl group having from 1 to 10 carbon atoms; and n represents an integer 60 7 GB2192729A 7 c) R R' so 3 Na 5 wherein R and R' each represents an alkyl group having from 1 to 6 carbon atoms d) - R 0 so 3 Na 10 wherein R and R' each represents an alkyl group having from 1 to 6 carbon atoms (9) Examples of the aliphatic anions include those derived from the following anionic surface 15 active agents.

(a) Alkylsulfonates of formula RSO,Na, wherein R represents an alkyl group having from 8 to carbon atoms (b) Dialkylsulfosuccinic acid esters of formula 20 ROOC-CH2 1 ROOC-Ut'_bU3Na, wherein R represents an alkyl group having from 2 to 20 carbon atoms 25 (c) Fatty acid amide sulfonates of formula RCON(CH3)C,HIS03Na, wherein R represents an alkyl group having from 4 to 20 carbon atoms (d) Higher fatty acid ester sulfonates of formula IRCO0C2H4SO,Na, wherein R represents an alkyl group having from 5 to 20 carbon atoms, and (e) Higher alcohol ether sulfonates of formula 30 ROCH,CHCH2SO,Na, OH 35 wherein R represents an alkyl group having from 5 to 20 carbon atoms The basic dyes which can be used in the present invention can be obtained by mixing an aqueous- solution of a commercially available basic dye containing a chlorine counter anion and an aqueous solution of a free acid of the above-described organic anion having 8 or more carbon atoms and one sulfonic acid group as a sole exchange group or a salt thereof with an 4G alkali metal, e.g., sodium and potassium, to form a water-insoluble dye through exchange reaction of the counter anion, and collecting the formed dye by filtration, followed by washing with water.

Counter anion compounds having less than 8 carbon atoms, e.g., 45 so -\5--so 3 and CH 3 3-' are disadvantageous because they form a tacky precipitate through the exchange reaction, which is difficult to filter and wash with water and also reduces the yield. 50 Anions which can be easily ion-exchanged include.

tC 4 H 9 So 3 e ("19 555001- 55 C0 GO 3 so 3 6 From the standpoint of mass production of dyes, these anions are very advantageous. The above-described dyes'according to the present invention can be used either individually or in 60 mixturps of two or more thereof. The amount of the dye to be used preferably ranges from 0.3 to 15% by weight based on the total weight of a positive photosensitive compositions. If desired, the photosensitive composition may further contain other dyes and pigments in a proportion of up to 70% by weight, and preferably up to 50% by weight, based on the total weight of the dyes and the pigment. 1 65 8 G132 192729A 8 To the positive photosensitive -composition according to the present invention can be added compounds whose photolysis products are capable of changing a hue of the dye through a mutual interaction with the dye. Such compounds include o-naphthqquinone- diazide-4-sulfonyI halogenides described in U.S. Patent 3,969,118 corresponding to Japanese Patent Application (OPI) 36209/75; trihalomethyl-2-pyrones and trihalomethyltriazines de scribed in U.S. Patent 5 4,160,671; various o-naphthoquinonediazide compounds described in British Patent 2,038,801; 2-trihalomethyl-5-aryl-1,3,4-oxa-diazole compounds described in U.S. Patent 4,279,982; and the like. These compounds may be used either individually or in combination thereof. The amount of these compounds to be added preferably ranges from 0.3 to 15% by weight based on the composition. - 10 The sensitivity of the photosensitive composition can be increased by addition of acid anhydride compounds described in U.S. Patent 4,115,128 corresponding to Japanese Patent Application (OPI) 80022/77. In addition the photosensitive composition of the present invention can further contain various additives, such as fillers, additives for improving coating properties, e.g., cellulose alkyl ethers, ethylene oxide surface active agents, and fluorine-containing surface pctive 15 agents (e.g., FC-430 or FC-431. produced by 3M), plasticizers for improving physical properties of a coating film,- e.g., dibutyl phthalate, butyl glycolate, tricresyl phosphate, dioctyl-adipate, etc., and the like. Addition of fillers-not only improves physical properties of a coating film but also makes it possible to mat a surface of a photosensitive layer to thereby improve vacuum adhesivity on image printing 'Examples of the fillers to be used include talc Powders, glass 20 powders, clay, starch, wheat flour, corn flour, polytetrafluoroethylene powders, etc., In carrying out coatingl the Photosensitive composition of the invention is dissolved in various organic solvents. The solvents to be used include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dic hloride, tetra hydrofu ran, toluenel ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monoethyl 25 ether, propylene glycol monomethyl ether, acetylacetone, cyclohexanone, diacetone a co o, et y lene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoi sopropyl ether, ethylene glycol monobutyl ether acetate, methoxymethoxyethanol, diethylene glycol monomethyl- ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol 30 monoethyl ether acetate, N,N-dimethylformamide, dimethyl sulfoxide, y- butyrolactone, etc. These solvents may be used either individually or in combinations thereof. A coating solution suitably has a solid concentration of from 2 to 50% by weight. A suitable solid coverage of the coating solution usually ranges from 0.5 to 3.0 g/M2. As the coverage becomes smaller, the photosensi tivity is increased but physical properties of the photosensitive layer, such as mechanical 35 strength, chemical strength,- development latitude, ink-receptivity, and the like, are deteriorated.

A developer for the photosensitive composition of the present invention suitably includes an aqueous- solution containing an inorganic alkali,(e.g., sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium tertiary phosphate, sodiumsecondary phosphate, ammonium tertiary, phosphate, ammonium Secondary phosphate, sodium metasilicate, 40 sodium bicarbonate, aqueous ammonia, etc.) or an organic-alkali (e.g., monoethanol'amine, dietha nolamine, etc.) at a concentration of from 0.1 to 10% by weight, and preferably from 0.5-to 5% by weight.

If desired, the alkali aqueous solution as a developer may futher contain surface active agents or organic solvents, e.g., alcohols. 45 The present invention will now be illustrated, in greater detail by way of the following examples, but it should be understood that the present invention is not deemed to be limited thereto. In these examplesi all the percents ar by weight unless otherwise indicated.

-50 EXAMPLES 1 TO 2 AND COMPARATIVE EXAMPLES 1 TO 13 50 A 0.3 mm thick aluminum plate (materiak, 1050) was dewaxed by washing with trichlene and subjected to brush grain Ing using a nylon brush and -a 400 mesh pumicewater slurry, followed by thoroughly washing with water, The aluminum sheet was then dipped in a 25% sodium hydroxide aqueous solution at 45'C for 9 seconds to effect etching, followed by washing with water. The amount of etched aluminium on the grained surface was about 3 g/M2. A direct 55 electric current was applied to the aluminum sheet at a current density of 15 A/dM2 in 7% sulfuric acid as an electrolyte to form an anodjc, oxidation film layer having a thickness of 3 g/M3. After washing with water and drying, a photosensitive composition having the following formulation was coated on the thus prepared aluminum support to be a dry coverage of 2.5 g/M2 and dried at 1000C for 2 minutes to obtain a positively working presensitized printing plate 60 precursor. - 9 GB2192729A 9 Photosensitive Composition Formulation:

Ester of naphthoquinone-l,.2-diazide- g 5-sulfonyl chloride and a pyrogallol- 5 acetate resin (disclosed in Example 1 of U.S. Patent 3,635,709) Cresol-formaldehyde resin 2.00 g 10 t-Butylphenol-f.ormaldehyde resin 0.05 (disclosed in U.S. Patent 4,123,279) Naphthoquinone-1,2-diazide-4- 0.03 g 15 sulfonyl chloride Dye of Table 1 shown in Table 1 Methyl ethyl ketone 8 g 20 2-Met.hoxyethyl-ace-tate 1-5 g 25, The amount of the dye added was selected so as to., result in an; image density of 0.9. 25 Each of the resulting presensitized printing plate precursors was exposed ta light for 120 seconds using a 30 A carbon arc lamp placed at a distance of 70 cm and then developed with a 3.0% aqueous solution of potassium silicate (SiO2/KO molar ratio= 1.30) at 25C' for 40 seconds by means of an automatic developing machine. The thus. produced printing plate was evaluated. for performances. according to the following methods, and the results obtained are 30 shown in Table 2, 1) Solvent Solubility: Solubility of the dye irl the organic solvents (methyl ethyl ketone/2- - methoxyethyl acetate) was rated according to the following scale:

35 Good... About 10 minutes were sufficient for complete disappearance of a residue. Poor... About 30 minutes were required for complete disappearance of a residue. Very... More than, about 50 minutes were required for complete disappearance of a residue-.- 40, poor 40 2) Stability with, Time:

Reduction, in image density of the printing, plate when: naturally left to stand for half a year was measured and rated as.follows.

Good No substantial reduction was observed. 45 Poor The density reduced by 0.1 Very The density reduced by 0.15 Poor 3) Sensitivity: 50 The printing plate precursor was exposed to light under the conditions described above through a step wedge: having '15 stages with a density difference of 0.15. The sensitivity was expressed by the number of steps cleared 4) Sludge: 55 The sludge in the developer after processing 1 M2 of the exposed printing plate precursor per liter was visually observed.

5) Color Remaining.:

The exposed printing, plate precursor was developed, with a fatigued developer after processing. 60 5 M2 of the precursor per liter. The degree of' color remaining was obtained by [(density of the non-image aera after development)-(density. of the uncoated aluminum supportfl.

6) Print-out Properties:

Print-gut properties were expressed by [(density of the non-image area)(density of the image 65 GB2192729A 10 area)] when exposed under the above-described conditions.

7) Hue:

The color sharpness of the coating film after drying was visually observed and rated---good- or -poor-. 5 8) Yiel d:

Expressed by a molar ratio (%) of the produced dye (after filtration) to the charged dye.

1.0 TABLE 1 10 Example Dye Amount No. Cation Anion Added (g) N(C[13) 2 15 ED G tC4H9 Example 1 (C113)2N C OIS-W 0. 0.27 20 N C-' 3 2 G Example 2 F\-COM'-n\ -So 3 0, 0'2 25 Comparative - E) Example -1 C13 -0-S03 0. 023 30 Comparative 0 0. 023 3 Example 2

35 COOH Comparative 0. 024L Example 3 b-SO3 G 40 Comparative so 0. 023 3-C -OH Example 4

45 Comparative 0, 02XL Example 5 C 1 2112 SCO()g Comparative C00e 50 Example 6 -q 0. 023 OH 1 GB2192729A 11 TABLE 1 (contId.) Example Dye Amount No. Cation Anion Added (g)..5 cool, 1 comparative. II 2 Example 7 1 10 Ul'1N11 2 0. 02.2 C2H4 Uk' 2 N11 2 Comparative Cee Example 8 0.01r (CH3)2 20 Comparative C000 Example 9, (C113)2 c: 0.04L \-/ 1 COOH 0 25 Comparative N (C 2 H 5 2 Example 10 (D 'l S 0 0. 0..t (C 2115 2N -c 30 0 0 35 11 11 C 2 0 CC- C=CH-CH=CH-Y, C- C- COC 2H 5 Comparative 11 l 11 11 Examole 11 N C=0 _c N n=l 0. 07S 4G N, HO 40 45 Comparative n=2 0. 0 7.r Example 12

12 GB2192729A 12 Example Amount No. _ Dye Added (9) Comparative B r. - 5 Examole 13 0 Cl.' 3 0.045 02N-0-N-N-C NC21,52 NO2 NI4COCH3 10 t TABLE 2 color Print-Out Solvent Stability Sensi- Remaining Property Example No. Solubility With Time tivity Sludge AD.) AD.) Hue Yield Example 1 good good 5 not 0.03 0.20 good 92 observed it 2 good good 5 not 0,03 0.21 good 89 observed Comaprative! good good 5 not 0.03 0.19 good 37 Example 1 observed 2 good good 5 not 0.03 0.23 good 25 observed 3 good good 5 not 0.09 0.19 good observed 4 good good 5 not 0,08 0.20 good observed good good 5 not 0.08 0.15 poor observed 6 good good 5 not 0.10 0.15 poor observed 7 good good 5 not 0.09 0.04 poor observed 8 very good 5 not 0.06 0.22 good poor observed w %-j /to be cont'd. co -r-l TABLE 2 (cont'd.) Color Print-Out Solvent Stability Sensi- Remaining Property Example No. Solubility With Time tivity Sludge O.D.) O.D.)_ Hue,Yield Comparative poor good 5 not 0.5 Example 9 observed very poor good 5 not 0.16 observed 11 good poor 4 not -observed 12 good very poor 5 not observed 13 good good 5 observed - G) co co _j co GB2192729A 15 As can be seen from Table 2, although the oil-soluble dyes of Comparative Examples 11 to 13 show satisfactory solubility in organic solvents,. the presensitized printing plates or precursors thereof obtained by using these dyes suffer from serious deterioration in essential performance that is attributable to the very oil solubility of the dyes. That is, they form a sludge in on alkaline developer particularly when the developer is fatigued as observed in Comparative Example 13; 5 the image density of the plate greatly decreases through long-term preservation as observed in Comparative Examples 11 and 12; or the photosensitivity of the photosensitive layer decreases through long-term preservation as is observed in Comparative Example 11.

The water-soluble basic dyes of Comparative Examples 8 to 10 are inferior in solubility in orgnaic solvents. Further, the basic dyes of Comparative Examples 9 and 10 having an oxalic 10 acid counter ion and a sulfuric acid counter ion, respectively have disadvantages of color remaining and low, contrast between image aeras and non-image areas.

In Comparative Examples 5 to 7 wherein the counter anion of the basic dyes is replaced by an organic carboxylic acid compound anion to render it oleophilic, solvent solubility of the dyes can be improved as expected, but in turn, color remaining resistance, print- out properties, and hue of 15 the resulting printing plate precursors are deteriorated as compared with those dyes having a chlorine counter anion.

To the contrary, the dyes according to the present invention containing a counter anion having one sulfo group as an exchange group exhibit improved solubility in organic solvents and, even when developed with an alkaline developer, they show higher resistance to color remaining 20 rather than those containing a chlorine counter.anion. With respect to other performances, such as stability with time, sensitivity, formation of no sludge in a developer, print-out properties, and hue, the dyes of the present invention are quire free from any problem, showing equality to those containing a chlorine counter anion.

On the other hand, the dyes of Comparative Examples 3 and 4 having a phenolic hydroxyl 25 group or a, carboxyl group in addition to a sulfon ' ic acid group as exchange groups have reduced resistance to color remaining. The dyes of Comparative Examples 1 and 2 which contain a sulfonic- acid group as a,sole exchange group but contains less than 8 carbon atoms have poor workability upon ion. exchange reaction due to their Tackiness and also result in very low-yields.

In this connection, the dyes of the present invention having a counter anion containing 8 or 30 more- carbon atoms can be obtained in the form of fine particles exhibiting satisfactory workabil ity in high yields.

EXAMPLES 3 TO 5-AND COMPARATIVE EXAMPLE 14 A 0.24 mm thick aluminum plate (material: 1100) was dipped in a 10% aqueous solution of 35 sodium tertiary phosphate kept at 80'C for 3 minutes to effect dewaxing. The dew axed alumi num plate was subjected to graining with a nylon brush and then etched by dipping in a 25% aqueous solution of sodium hydroxide at 45'C for 20 seconds, followed by washing with water.

After desmutting with a 3% aqueous solution of sodium hydrogensulfate, the aluminum plate was anodically oxidized in 15% sulfuric acid at a direct-current density of 20 A/dM2 to form an 40 anodic oxidation film to a thickness of 3.5 g/M2. After washing with water and drying, a photosensitive coating composition having the following formulation was coated on the thus prepared aluminum support'and dried at 100'C for 2 minutes, 16 GB2192729A 16 Photosensitive Composition Formulation:

-Ester compound of naphthoquinone- 0.85 9 ('1,2y-diazido--(2)-5-sulfonyl chloride 5 and a-pyrogallol-acetone resin Cr-e-sol.-formaldehyde resin2.10 g 10 HexahYdrophthalic anhydride 0.15 g o--Naphthoquinonediazido-4-sulfonyl 0.02 g chIori - de 15 2--(p-Methoxystyry,l)-4,6-bis(tri- 0-01 9 chlOromethyl)-s-triazihe Ethylene dichlor_ide- 16 9 20 2-Methoxyethyl acetate--- 12 9 Dye of-Table 3 shown-in Table 3 p. -.. 25 The- amount of the dye added was determined so as to obtain an image density of 0.9.

Each of the resulting photosensitive layer was exposed to light and developed in the same manner as in- Example -1, and evaluations were made in the same manner as in Example 1. The results obtained are shown in Table 4. As is apparent from the results of Table 4, solvent solubil ity and color remaining of dyes used in Examples 3 to -5 are superior to those containing 30 a chlorine counter anion, and print-out properties:and hue are free from any problems, showing equality to those containing a chlorine counter anion, which results are the same as in Examples 1 and 2.

The results show high yields of produced dyes, as is the same as in Examples 1 and 2.

Further, the printing plate thus produced is also free from any problems in printing. 35 17 GB2192729A 17 TABLE 3

Example Dye -Amount No. Cation Anion Added (9) 5 (C2115) 2N S03 E) 1 10 Example 0\ E) 10 3 d=C)--N (C 2 H5 2 0. 02 57 C2115-Nl'1 15 t C 4 H 9 Example 0.03 20 4 3 COCH3 25 Example 0. 03

E) 3 Compara- cú 9 0. -0.2.2 30 tive Example

14 TABLE 4 35

Print-Out Color Solvent Property Remaining Examole No. Solubility AD.) AD.) Hue Yield (%) 40 Example 3 good 0.25 0.02 good 95 4 good 0.26 0.02 good 90 5 good 0.24 0.02 good 90 '45 Comparative very poor 0.25 0.07 good Example 14

EXAMPLES 6 TO 12 50 Presensitized printing plates, inclusive of precursors, were produced in the same manner as in Example 1, except for using dyes shown in Table 5 below. When each of the resulting products were evaluated in the same manner as in Example 1, satisfactory results could be obtained.

18 GB2192729A 18 TABLE 5

Example D-Sre

No. Cation, Anion (CF13) 2 (CH3) 2N--jr Ee, 6 CH2 S03e 10 N(CH3)2 7 0 t-C 4H9 S03 E). 15 - -0-.

(C2H5) 2N--O - N (C 2H5) 2 20 \C':' (D 8 C S03e -:,-,- - O-ON114-0 25 (C2Hs) 2 OCOCH3 9 30 S03e 0 11 35 CsHii-O-C-CH2 I E) C 5H1 1-0-C-CH-SO 3 40 11 C6H13CON(CH3)C2H4SO3E) 45 S03 6 CH=CH_\ /-IN (CH3)2 j 12 j 50 0 - C C2HS While the invention has been described in detail and with reference to specific embodiments 55 thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the scope of the appended claims.

Claims

1. A presensitized printing plate precursor comprising a grained and anodically oxidized alumi- 60 num support having provided thereon a positively working photosensitive layer containing a dye, wherein said dye is a salt formed between a basic dye cation and a counter anion, said counter anion being an organic anion having 8 or more carbon atoms and one sulfonic acid group as a sole exchange group.

2. A presensitized printing plate precursor as claimed in claim 1, wherein said basic dye 65 19 GB2192729A 19 cation is one derived from triaryimethane dyes, xanthene dyes, acridine dyes, azine dyes, oxazine dyes, thiazine dyes, cyanine dyes, methine dyes, polymethine dyes, anthraquinone dyes, azo dyes or mixture thereof.

3. A presensitized printing plate precursor as claimed in claim 1, wherein said basic dye cation is one derived frory triaryimethane dyes, xanthene dyes, acridine dyes, azine dyes, oxazine 5 dyes, thiazine dyes, cyanine dyes or a mixture threof.

4. A presensitized printing plate precursor as claimed in claim 1, wherein said basic dye cation.is at least one cation selected from cations -represented by formula (1) and (11); 111\ N-O\C -N R5 10 R2 R6 R3 15 N,& xe R i or formula - 20 R, "N-01 \ R 2, R

5 25 R 3 C R N X e R-' 30 g - - 4 wherein R, R2, R, R, R, and R, each represents an alkyl group having from 1 to 3 carbon atoms or a substituted or unsubstituted aryl group. 35 5. A presensitized printing plate precursor as Claimed in claim 1, wherein said counter anion is at least one anion selected from the following anions; 40 J7\ 0 e _Cl e 0 N H- -503 45 OCOCH,_ 50 -G z, S 10 3 SO Y02 55 3 60 803 CO 2-0 GB2192729A 20 CH2=CH S03 5 (7) CH3OCO-// \SOB 10 (8) Anions derived from the following alkylaryisuifonates anionic surface active agents:

Na R"f \I-SO3 1-5 15.

wherein R represents an alkyl group having from 2 to 16 carbon atoms b) R 20 1 _W 1 - - so 3 Na wherein R represents an alkyl group having from 1 to 10 carbon atoms; and n represents an integer 25 c) R R' S03 Na 30 wherein R and R' each represents an alkyl group having from 1 to

6 carbon atoms d) R 35 "C_ 0 -6,'SO 3 Na wherein R and R' each represents an alkyl group having from 1 to 6 carbon atoms (9) Anions derived from the following anionic surface active agents. 40 (a) Alkylsulfonates of formula RS03Na, wherein R represents an alkyl group having from 8 to carbon atoms (b) Dialkylsulfosuccinic acid esters of formula ROOC-CH2 45 1 1 ROOC-CH-SO31\1a, wherein R represents an alkyl group having from 2 to 20 carbowatoms EO (c) Fatty acid amide sulfonates of formula IRCON(CH,)C^_SO3Na,, wherein R represents an alkyl 50 group having from 4 to 20 carbon atoms (d) Higher fatty acid ester sulfonates of formula RCOOCASO,Na, wherein R represents an alkyl group having from 5 to 20 carbon atoms, and (e) Higher alcohol ether sulfonates of formula 55 ROCH2CHCH2SO,Na, OH wherein R represents an alkyl group h aving from 5 to 20 carbon atoms 60 6. A presensitized printing plate precursor as claimed in claim 1, wherein said counter anion is at least one anion selected from 21 GB2192729A 21 tc 4 H 9 so 3 9 so 3 - 01 ard 5 so 3 wherein tC,Hg represents a t-butyl group.

7. A presensitized printing plate precursor as claimed in claim 1, wherein said dye is used in 10 an amount of from 0.3 to 15% by weight based on the total weight of a positively working photosensitive composition.

8. A presensitized printing plate precursor as claimed in claim 1 substantially as described in any one of Examples 1 to 12.

9. A printing plate prepared by imagewise exposure and development of a presensitized 15 printing plate precursor as claimed in any one of claims 1 to 8.

Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC1R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.