DE4330279A1 - Presensitised lithographic printing with minimised edge peel plate - has silicone rubber layer obtd. from mixt. of alkenyl-substd. polysiloxane(s) with different mol.wt. cured with hydrido-polysiloxane - Google Patents

Abstract

PS dry lithographic printing plate has a substrate with light-sensitive coat (I) covered by a silicone rubber layer (II), obtd. by addn. cure of: (a) a basic polymer mixt. of 50-95 (wt.)% polysiloxane (IIIA) and 5-50% polysiloxane (IIIB) contg. at least 2 Si-bound alkenyl gps./ml. and gps. of the formula -(Si(R1)(R2)-O)k (III) and (b) a hydridopolysiloxane of the formula R1-Si(R4)2-O-(SiH(R4)-O)m-(Si(R4)2-O)n-Si)R4)2-R3 (IV) (where R1-2 are at least 70% Me, rest (ar)alkyl, aryl, vinyl or halohydrocarbyl; k is 100-500 in (IIIA) and k is 700-10000 in (IIIB); R3 is H or Me; R4 is at least 70% Me, rest (ar)alkyl, aryl or vinyl; and m + n is 4-100 and n/m is 0-1). The (IIIA):(IIIB) ratio is 70:30 to 90:10; and the amt. of (IV) 4-15 equiv. Si-H gps./equiv. unsatd. C-C gps. in (III). (II) pref. also contains a siloxane of the formula (R5)3-SiO-(Si(R5)2-O)p-(Si(R6)(R7)-O)q-Si(R5)3 (V) where R5 is 1-4C alkyl; R6-7 are a substd.) aromatic gp. or one of R6-7 = (substd.) alkyl; p/q is 99/1 to 10/90). (II) has a thickness of 0.5-5 g/m2. It has a protective coating produced by laminating with a transparent, opt. oriented and/or matted polyethylene, polypropylene, PVC, PVDC, PVA, PET or 'Cellophane' (RTM) film or by coating with one of these polymers. (I) contains a monomer, oligomer or macromonomer with photopolymerisable ethylenically unsatd. gp(s)., a film-forming polymer and photopolymerisation initiator. ADVANTAGE - (II) does not peel off as a result of loss of sensitivity caused by pressure changes at the edge of the original film during evacuation. The plate has good resistance to background soiling during printing and gives large editions.

Description

The present invention relates to a presensitized Plate for use to make a lithogra phical pressure plate, which benö no moistening water which comprises a substrate on which in said Sequence provided are a photosensitive layer and a silicone rubber layer in which substantially no detachment of the silicone rubber layer in areas correspond to the margins of an original transparency film,  occurs as a result of a reduction in sensitivity by pressure changes on the margins of an origi nalfilms during the imagewise exposure, resulting in a insufficient exposure leads, and a significant ver improved resistance to background contamination (Background contamination) during printing and one has significantly improved print durability.

There are already different types of presensitized Plates have been proposed for use with Her position of lithographic printing plates which are not An need dampening water, the practical through management of lithographic printing operations without Ver allow use of any moistening water (hereinafter referred to as "dry PS plates", and the prepared by treating the dry PS plate thographic printing plate that does not dampen water is required hereinafter as "dry lithographic Pressure plate "). Among these are dry PS Plates each having a substrate on which in in the order mentioned, a primer is provided Layer, a photosensitive layer and a silicone rubber layer, preferred because of their excellent Quality and specific examples are included For example, in the Japanese patent publications for Op positioning purposes (hereinafter referred to as "JP Kokoku") No. Sho 54-26 923 (corresponding to U.S. Patent 3,894,873), Sho 55-22 781 (corresponding to British Patent 1,419 643) and Sho 56-23 150 and in the unaudited Japanese Patent Publication (hereinafter referred to as "JP Kokai") No. Hei 2-236550.

As the silicone rubber layer, in these dry PS Plates currently uses those that are obtained by partial crosslinking of polymers containing polysiloxane Containing residues as the main backbone, with crosslinking stuffs. So far, the two indicated below  Method for curing the silicone rubber layer angewen det:

• 1) condensed silicone rubber layer: a polysiloxane with hydroxyl groups at both ends is cross-linked with ei a silane or a siloxane that is directly attached to a sili ciumatom of the same bound hydrolyzable functional Group wears to form a silicone rubber;
• 2) Addition type silicone rubber layer: a polysi loxan with ≡Si-H groups and a polysiloxane with -CH = CH- Groups are subjected to an addition reaction Formation of a silicone rubber (cf., for example, JP KOKAI no. Sho 61-73 156 and Hei 3-161 753).

The condensed silicone rubber (1) causes changes conditions of its curing properties and its adhesion a photosensitive layer depending on the amount of moisture Keep the atmosphere during curing, and with him Therefore, the problem arises that when he to Her Position of a dry PS plate is used, the Sensitivity thereof varies slightly and their stable Production is very difficult. For this reason, the An addition-type silicone rubber (2) is considered to be better hen, because he does not have these disadvantages.

When an addition type silicone rubber is used but should dry the PS plate at the same time the requirements for a high resistance ge gene background contamination (background contamination) during printing or copying (under the Off print "Background contamination or background pollution tion "is to be understood that a small amount of the verwen Dye ink on the non-image area of a lithograph Phisic pressure plate adheres and so contamination (Pollution) causes the resulting copies) and with respect to a high pressure durability suffice. This means  in other words, the resistance to background Contamination and print durability of a dry lithographic printing plate are in contrast to each other the. When the degree of cure of the silicone rubber In particular, the addition type is excessively increased the print durability of the resulting dry litho graphic printing plate improved, the resistance ge However background contamination of the same is thereby detrimentally affected, while then when the Degree of curing of the silicone rubber excessively low is set, the resistance against background Kontami nation of the resulting dry lithographic Pressure plate is improved, but their print durability impaired (worsened). It is therefore since then long desired to develop a dry PS plate, at the same time these two contradictory Properties are enough.

On the other hand, usually the evacuation technique applied to the adhesion of an original film to a Dry PS plate during imagewise exposure improve for the purpose of preventing the "formation of a blurred image. "In general, a soft sili use a rubber layer in a dry PS plate det. For this reason, the edge sections of a Original film deformed as a result of during bildmalsi Gen Exposure carried out evacuation, and the Sensitivity at the edge sections becomes clear deposited or the edge portions of the dry PS plate are exposed incompletely. As a result, it dissolves the silicone rubber layer during the development of the PS plate and as a result serve the edge sections same as image sections during the print job transitions. This problem has been solved by increasing the Amount of light for the exposure, to ensure adequate exposure tion of the edge sections to ensure or by Off deleting these parts with an extinguishing solution. These  However, methods are known as plate-making method effective and it was therefore desirable to have an improved Ver drive to develop, with the help of these disadvantages can be eliminated.

An object of the present invention is therefore to provide a to create dry PS plate, free of a Ablö solution of the silicone rubber layer as a result of the reduction Sensitivity due to pressure changes to the Edge sections of an original film during the evacuation tion and a dry lithographic printing plate with a good resistance to background contamination tion during printing and excellent printing durability can result.

The above object of the invention can be achieved with an improved dry PS plate, which includes Substrate, provided on the in the order mentioned are a photosensitive layer and a silicone rubber layer, wherein the silicone rubber layer Herge is prepared by crosslinking the following components (a) and (b) by an addition reaction:

• a) a mixture of polysiloxanes (base layers), each having in its molecule at least two directly to silicon umatome bound alkenyl groups and groups of the formula - (Si (R ¹ ) (R ² ) -O) _k - (wherein R ¹ and R ² each represent an alkyl, aryl, aralkyl, vinyl or halogenated hydrocarbon group, with the proviso that at least 70% of these groups R ¹ and R ^{2 are} methyl groups), the mixture comprising (i) 50 to 95 % By weight of the polysiloxane having an average number k of recurring units within the range of 100 to 500 and (ii) 5 to 50% by weight of the polysiloxane whose average number k of repeating units is in the range of 700 to 10,000 (the sum of (i) + (ii) equals 100% by weight) and
• b) a hydrogenpolysiloxane of the following general formula: R³-Si (R⁴) ₂-O- (SiH (R⁴) -O) _m - (Si (R⁴) ₂-O) _n -Si (R⁴) ₂-R³ (I ) (wherein R ³ represents a hydrogen atom or a methyl group; R ⁴ represents an alkyl, aryl, aralkyl or vinyl groups, with the proviso that a plurality of R ³ or a plurality of the radicals R ^{4 are} identical or may be different and that at least 70% of the radicals R ^{4 are} methyl groups, and wherein m + n is a number from 4 to 100 and n / m is a number from 0 to 1).

As indicated above, the silicone rubber of Additi Ons type can be obtained by curing by reaction the alkenyl groups of the base polymer having Si-H groups, which are present in the crosslinking agent. The top The object of the invention is achieved by use of a hydrogenpolysiloxane at a high rate in the Molecule present Si-H groups which the improvement the efficiency of curing the silicone rubber and the strength of the resulting silicone rubber film, and by mixing a base poly low molecular weight mers as a major compo nenten with a base polymer with a high Molekularge weight (although the three-dimensional structure of the hardened th silicone rubber is not yet cleared), the one Improvement of ink repellency of the resulting Silicone rubber layer allowed.

The present invention will be described below in more detail ben.

The dry PS plate and the resulting troc kene lithographic printing plate must be so flexible that they can be placed on the usual printing press  and at the same time acting during the printing process can withstand the load. Therefore belong to typi Examples of substrates according to the invention ver reversible, coated paper, metal plates like one Aluminum plate, plastic films like a polyethylene terephthalate film, rubber and composites thereof. The surface of the substrate may be covered with a primer layer be provided to prevent a halation (halo education) and for other purposes.

The substrate may optionally contain a silane coupler surface treated to improve adhesion between the substrate and a photosensitive layer or a primer layer, which is subsequently applied to it as described in JP KOKAI No. Hei 4-3166.

Different types of primer layers can be used for Ver Improvement of the adhesion between a substrate and a photosensitive resin layer for preventing Ha lation (halation) and to improve the image on dyeing and printing properties the. Specific examples include such as they are obtained by curing a variety of photosensitive polymers by the action of light before applying a photosensitive resin layer, as described in JP KOKAI No. Sho 60-229 031; those that be formed by curing of epoxy resins by Er heat as described in JP KOKAI No. Sho 62-50,760; those obtained by curing gelatin, such as in JP KOKAI No. Sho 63-133 151 (corresponding to US Pat 861,698); those made from urethane resins and Silane couplers, as described in JP KOKAI No. Hei 3-200 965, and those made of urethane resins as disclosed in JP KOKAI No. Hei 3-273,248 wrote. Moreover, it is also effective to use such those obtained by hardening casein.  

The primer composition may be softened to soften it a polymer with a glass transition point of no more as room temperature, z. As a polyurethane, polya mid, styrene / butadiene rubber, carboxylic acid modified Styrene / butadiene rubber, acrylonitrile / butadiene rubber, Carboxylic acid-modified acrylonitrile / butadiene rubber, Polyisoprene, acrylate rubber, polyethylene or chlorin polyethylene or polypropylene. The amount of it is the same not critical, as long as the composition containing it tion can form a film layer. Alternatively, the Primer layer also from the above polymer alone getting produced.

The primer composition may contain other additives, e.g. A dye, a pH indicator, an agent or composition for forming a visible image immediately after imagewise exposure, a photopolymerization initiator, an adhesion promoter (adhesion) (e.g., a polymerizable monomer, a diazo resin , a silane coupler, a titanate coupler or an aluminum coupler), a pigment and / or silica powder, depending on the purpose. In general, the amount of the primer layer to be applied to the substrate is desirably in the range of 0.1 to 20 g / m ² and preferably 1 to 10 g / m ² (weighed after drying).

The photosensitive resin used in the present invention Layer can be a photopolymerizable photosensitive Layer, a photocrosslinkable photosensitive layer or a photosensitive layer containing a diazo resin and a binder resin.

The photopolymerizable photosensitive layer ent holds at least (1) a monomer, oligomer or macromono that at least one photopolymerizable, ethyle nically unsaturated group bears; (2) a polymeric compound  with a film-forming ability; and (3) a photograph polymerization initiator.

Component (1): monomer. Oligomer or macromonomer, the at least one photopolymerizable ethylenic unge saturated group wears

The photopolymerizable used in the invention photosensitive layer comprises or contains at least a monomer, oligomer or macromonomer that is at least a photopolymerizable, ethylenically unsaturated Group in molecule carries. Examples of the above called monomer, oligomer, or macromonomer that invented Usable according to the invention, the following are listed below counted connections:

• A) (meth) acrylates of alcohols, such as ethanol, propanol, Hexanol, 2-ethylhexanol, cyclohexanol, glycerol, hexane diol, trimethylolpropane, pentaerythritol, sorbitol, tri ethylene glycol, polyethylene glycol and polypropylene glycol;
• B) reaction products of amines (such as ethylamine, butylamine, Benzylamine, ethylenediamine, hexamethylenediamine, diethylene triamine, xylylenediamine, ethanolamine and aniline) with glycine dyl (meth) acrylate or allylglycidyl;
• C) reaction products of carboxylic acids (such as acetic acid, Propionic acid, benzoic acid, (meth) acrylic acid, amber acid, maleic acid, phthalic acid, tartaric acid and citrons acid) with glycidyl (meth) acrylate or allylglycidyl; and
• D) amide derivatives (eg acrylamide, N-methylolacrylamide, t-butyl) Butylacrylamide, methylenebisacrylamide and diaceto nacrylamid).

Examples of these monomers, oligomers and macro monomers also include urethane acrylates, e.g. B. such as  in JP Kokoku Nos. Sho 48-41 708 and Sho 50-6 034 and in JP KOKAI No. Sho 51-37193; poly ester acrylates, e.g. Such as those described in JP KOKAI No. Sho 48-64 183 and JP Kokoku Nos. Sho 49-43191 and Sho 52-30 490 are described; polyfunctional (meth) acrylates, e.g. B. Epoxy acrylates obtained by reactions of epoxy resins with (Meth) acrylic acid are obtained; N-Methylolacrylamidderi father, z. For example, as described in US Pat. No. 4,540,649 are written; such as the "Bulletin of Adhesives Society of Japan, 1984, Vol. 20, No. 7, pp. 300-308, as photohardenable monomers and oligomers are described; and Macromonomers as described in P. Dreyfuss and R.P. Quirk in "Encycl, Polym Sci. Eng.", 1987, 7, p. 551, in KAGAKU KOGYO (Chemical Industries), 1987, 38, page 56, and in KOBUNSHI KAKO (Polymer Processing), 1986, 35, page 262, are described. However, the present invention is not limited to these specific examples. The The above-mentioned polyfunctional monomers may respectively simultaneously have at least two groups out are selected from the group, for example from acrylic, methacrylic, allyl and vinyl groups. This mo monomers, oligomers and macromonomers may be alone or be used in the form of a combination. Your lot is in the range of 5 to 80 wt .-%, preferably from 30 to 70 wt .-%, based on the total solids content the photopolymerizable photosensitive layer.

Component (2): polymers with a film-forming ability

The photopolymerizable used in the invention photosensitive layer comprises or contains at least a film-forming polymer. Examples of this film forming polymeric compounds ver according to the invention ver include polyester resins, vinyl chloride / Vi nylacetate copolymers, acrylic resins, polyamide resins, Ep oxy resins, (meth) acrylate copolymers, (meth) acrylamide copo polymers, polyurethane resins, vinyl acetate copolymers, polysty  rol, phenoxy resins, polyvinyl chloride, acid cellulose derivatives alkane, alcohol-soluble polyamides, (meth) acrylic acid copoly mers, maleic acid copolymers, polyvinyl alcohol, water-soluble Liche polyamides, water-soluble polyurethanes, wasserlösli cellulose and polyvinylpyrrolidone. In addition to the The above-mentioned polymeric compounds may also be used be used on the side chains photopolymerizable or photocrosslinkable olefinic un have saturated double bonds. The present He However, finding is not specific to these specific examples limited. The amount of the film-forming polymeric compound is in the range of 10-80 wt .-% and preferably 25-65 wt .-% based on the total weight of the composition drove the photopolymerizable photosensitive layer.

Component (3): photopolymerization initiator

Typical examples of photopolymerization initiation as described in the photopolymerizable lichtempfindli Chen layer of dry PS plate according to the invention used include those listed below Links:

• a) benzophenone derivatives, such as benzophenone, Michler's ketones, Xanthone, anthrone, thioxanthone, acridone, 2-chloroacridone, 2-chloro-N-n-butylacridone, 2,4-diethylthioxanthone and fluorenone;
• b) benzoin derivatives such as benzoin, benzoin methyl ether and benzoin ethyl ether;
• c) Quinones such as p-benzoquinone, β-naphthoquinone and β-Me thylanthrachinon;
• d) sulfur atom-containing compounds, such as dibenzyl disulfide and di-n-butyl disulfide;
• e) azo or diazo compounds, such as 2-azobisisobutyroni tril, 1-azo-bis-1-cyclohexanecarbonitrile, p-diazoben cylethylaniline and Congo red;  
• f) halogen atom-containing compounds, such as tetrabromide carbon, silver bromide, α-chloromethylnaphthalene and Trihalomethyl-s-triazine type compounds; and
• g) peroxides such as benzoyl peroxide.

In the photosensitive layer, these photopoly use polymerization initiators alone or in combination and the amount in which they are inserted into the shift to work is in the range of 0.1 to 25 wt .-%, preferably from 3 to 20 wt .-%, based on the total weight of the photopolymerizable photosensitizer composition.

Other (further) components

In addition to the above components, the photopolymerizable photosensitive composition preferably further additives, such as. B. a heat polymer inhibitor, such as hydroquinone, p-methoxyphenol, di- t-butyl-p-cresol, pyrogallol, t-butylpyrocatechol, benzo quinone, 4,4'-thiobis- (3-methyl-6-t-butylphenol), 2,2'-Me thylenebis- (4-methyl-6-t-butylphenol) and 2-mercaptobenz imidazole and optionally a pigment or a color A fabric for dyeing the photosensitive resin layer and / or a pH indicator or a leuco dye as Dye, pigment or as an agent or composition for Take an image immediately after exposure.

The photosensitive layer may also vary depending on Ver use a small amount of a silicone compound, such as polydimethylsiloxane, methylstyrene-modifi grained polydimethylsiloxane, olefin-modified polydi methylsiloxane, polyether-modified polydimethylsi loxan, a silane coupler or silicone di (meth) acrylate.  

The photosensitive composition may also have an upper silicone surfactant or fluorine atom containing surface active agent are incorporated to Improvement of their coating properties.

In addition, a diazo resin of the photosensitive layer be added to improve the adhesion between the photosensitive resin layer and the primer layer.

In addition, a plasticizer (eg., Polyethylenglycol or tricresyl phosphate), the resulting coating flexibility, and / or a Stabilisa tor (eg, phosphoric acid) of the photosensitive composition be added.

The amount of these optional additives be generally does not contribute more than 10% by weight, based on the total weight of the photosensitive composition.

The photosensitive composition may optionally a hydrophobic silica powder whose Surface with a (meth) acryloyl or allyl group-containing silane coupler has been treated in an amount of not more than 50% by weight, based on the Total weight of the composition, for the purpose of the verb the liability of the latter subsequently applied silicone rubber layer.

The photosensitive layer of troc kenen PS plate can also be made of a photosensitive Made of a diazo resin and composition contains a binder resin. The in the photosensitive Layer used Diazoharze can be, for example Condensates of aromatic diazonium salts with formaldehyde hyd. Among these, particularly preferred are salts of Kon densates of p-diazodiphenylamine with formaldehyde or Acetaldehyde, e.g. For example, inorganic salts of diazo resins, the  Reaction products of the abovementioned condensates with He xafluorophosphate, tetrafluoroborate, perchlorate or perjo represent dat; and organic salts of diazo resins, the Reaction products of the abovementioned condensates with sulfone acids as described in U.S. Patent 3,200,309 wrote. The amount of in the photosensitive layer used diazo resin is in the range of 20 to 95 Wt .-%, preferably from 35 to 80 wt .-%.

Various polymeric compounds can be used as binders telharz components in the photosensitive composition be used and examples of which are preferred used are copolymers of monomers with aroma hydroxyl groups, such as N- (4-hydroxyphenyl) (meth) acrylamide, o-, m- or p-hydroxystyrene and o-, m- or p- Hydroxyphenyl methacrylate with other monomers containing the above-mentioned monomers are copolymerizable, as in JP Kokai No. Sho 54-98613, polymers which are known as main recurring units have such which are derived from hydroxyethyl (meth) acrylate, as in U.S. Patent 4,123,276; Copolymer resins with Recurring units derived from a phenolic hydro xylgruppe containing monomers are derived, and as repeating units by an alcoholic hydro xylgruppe containing monomers are derived, as in JP Kokai No. Hei 3-158 853; natural resins, like shellac or rosin; polyvinyl alcohol; Polyamide resins, as described in U.S. Patent 3,751,257, linear Po polyurethane resins as described in US Patent 3,660,097 ben; Phthalate-modified polyvinyl alcohol resins, Ep oxy resins obtained by condensation of bisphenol A with epi chlorohydrin, and celluloses, such as Cellulo Sebutyrate and cellulose acetate.

In addition, the binder resins may be those which mainly photosensitive polymers such as Po lyester, polyamides and polycarbonates, each as  light-sensitive groups -CH = CH-CO groups in the main chain and in the side chains of the polymer. To spe Examples include photosensitive poly esters, which are obtained by condensation of Phe nylendiethylacrylat, hydrogenated bisphenol A and triethy glycol as described in JP KOKAI No. Sho 55-40415; and photosensitive polyesters derived from (2-propenylidene) malonate compounds, e.g. B. cinnamylidene malonate and bifunctional glycols, as in the US patent 2,956,878.

The above photosensitive layers which contain these diazo resins, other (further) Contain additives such. B. dyes, surface-active Agents, plasticizers and / or stabilizers, wherein spe Examples of this are the same as above in conjunction with the abovementioned photopolymerizable light-sensitive composition have been listed.

Alternatively, the photosensitive layer of the inventions dry PS plate according to the invention also a photocrosslink be bare photosensitive layer, as above has been described. The photocrosslinkable photosensitizer Liche layer can be made from any, in the state of Technique known photocrosslinkable photosensitive Zu composition are produced.

The above photosensitive composition is applied to the surface of each substrate in the form of a solution in a suitable solvent, e.g. For example, in 2-methoxyethanol, 2-methoxyethyl acetate, propylene glycol methyl ethyl acetate, methyl lactate, ethyl lactate, Propylengly colmonomethyläther, ethanol, methyl ethyl ketone, N, N-Dime thylacetamid or a mixture thereof. The amount in which they are to be applied is in the range of 0.1 to 20 g / m ² , preferably 0.5 to 10 g / m ² (weighed after drying).

The silicone rubber layer used according to the invention, the ink-repellent layer of the resulting dry lithographic printing plate, comprises or contains the following components:

• a) a mixture of base polymers, ie polysiloxanes, each having in the molecule at least two alkenyl groups (eg vinyl, butenyl, hexenyl and decenyl groups, the vinyl groups being preferred), which are bonded directly to silicon atoms, and also groups of the formula - (Si (R ¹ (R ² ) -O) _k - (wherein R ¹ and R ² each represent an alkyl group, for example, a methyl or ethyl group, an aryl group, for example, a phenyl group, an aralkyl group, e.g. B. a β-phenylpropyl group, a vinyl group or a halogenated Kohlenwas hydrogen group, such as a chloromethyl or 3,3,3-trifluoropropyl group, with the proviso that at least 70% of these groups R ¹ and R ^{2 represent} methyl groups), where in the mixture contains (i) 50 to 95 wt .-% of Polysi loxans whose average number k of recurring units in the range of 100 to 500, and (ii) 5 to 50 wt. -% of the polysiloxane whose average number k of the again repeating units is in the range of 700 to 10,000 (where the sum of (i) and (ii) equals 100% by weight). At least three types of polysiloxanes can be used. The mixing ratio (i) / (ii) is preferably in the range of 60/40 to 95/5, and especially 70/30 to 90/10, be based on the weight.
• b) The crosslinking agents used in the silicone rubber layer of the dry PS plate are hydrogenpolysiloxanes of the above general formula (I). Particularly preferred hydrogenpolysiloxanes are, for example, those of the following general formula: (CH₃) ₃-Si-O- (SiH (CH₃) -O) _m - (Si (CH₃) ₂-O) _n -Si (CH₃) ₃

Preferably, those are used in which m and n satisfy the following relations: (m; n) = (5 to 50; 0), (5 to 50, 5), (10 to 80, 10) or (20 to 80, 20) and in particular (5 to 40; 0). These hydrogenpolysiloxanes can be used alone or in combination become.

The mixing ratio between the alkenylpolysiloxane and the hydrogenpolysiloxane is determined in the manner that the amount of the latter expediently not less than 2 Equivalents and preferably 4 to 15 equivalents, expressed by the amount of Si-H groups per unit Equivalent amount of those present in the alkenylpolysiloxane unsaturated carbon-carbon groups.

The catalysts for the addition reaction of this compo Nuclei may be arbitrarily removed from those in the prior art known catalysts are selected. In particular they are suitably selected from platinum compounds, such as elemental platinum, platinum chloride, chloroplatin (IV) acid and platinum, which is coordinated with olefins.

The composition for the silicone rubber layer may further contain a crosslinking inhibitor, for example example, a vinyl group-containing organopolysiloxane, such as tetracyclo (methylvinyl) siloxane, an alcohol with egg a carbon-carbon triple bond, acetone, Me ethyl ethyl ketone, methanol, ethanol or propylene glycol mono methyl ether to the cure rate to control (control) the composition.

These compositions undergo an addition reaction tion as soon as the abovementioned three components are involved which are mixed and thus initiates their hardening becomes. It should be noted, however, that the Aushär processing rate of the composition  rises rapidly as the reaction temperature increases becomes. For this reason, it is necessary to the pot life or the time between their production and their conversion elongation in rubber and that for curing the same on a photosensitive layer erforderli time to shorten. For this purpose, the Zusammen cured preferably in a temperature range, the properties of a substrate and a lichtemp sensitive resin layer is not affected, and it is before preferably kept at a high temperature until they completely cured. This way a can stable adhesion to the photosensitive resin layer ge be ensured.

In addition to the above components, the Zu Composition may contain a known adhesive sion-conferring agent such. B. an alkenyltrialkoxysi lan and / or other additives, eg. B. fine powder of anorga nical substances, such as silicon dioxide, calcium carbonate and titanium oxide, auxiliary adhesives, such as silane couplers, Titanate type couplers and aluminum type couplers, Si licon oil and / or polymerization initiators.

The silicone rubber layer may optionally contain a silicon atom-containing compounds by the following general formula (II), for the sake of improvement Ablösungsvermögens a coating film (as white described below), which refers to the silicone rubber layer is applied to the layer or the ink to protect pointing layer:

(R⁵) ₃-SiO- (Si (R⁵) ₂-O) _p - (Si (R⁶) (R⁷) -O) _q -Si (R⁵) ₃ (II)

(wherein R ^{5 's may be the} same or different and each represents an alkyl group having 1 to 4 carbon atoms, R ⁶ and R ^{7 may} also be the same or different and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted one with the proviso that at least one of R ⁶ and R ^{7 represents} a substituted or unsubstituted aromatic group, and p / q (molar ratio) is within the range of 99/1 to 10/90), e.g. For example, those described in JP KOKAI No. Hei 1-179,047. Specific examples thereof include those listed below, but the present invention is not limited to these specific examples.

(CH₃) ₃SiO- (Si (CH₃) ₂-O) _p - (Si (CH₃) (CH₂CH (CH₃) -C₆H₅) -O) _q -Si (CH₃) ₃ (p / q = 75/25;
MG = about 2 × 10⁴)

In addition, a release agent, as in the state of Technology is well known, the silicone rubber layer be added.

The silicone rubber layer used in the invention serves as an ink-repellent (repelling) layer. Therefore, if their thickness is too low, their ink repellency is reduced and the layer tends to be damaged. On the other hand, if it is too thick, its developability is impaired. Therefore, its thickness is suitably in the range of 0.5 to 5 g / m ² , preferably 1 to 3 g / m ² (weighed after drying).

The above discussed dry PS plate may also ver different types of ink repellent (repulsive) Have layers based on the above-mentioned silicone rubber layer (i.e., the ink-repellent layer) be applied. The dry PS plate can also be a Adhesive layer between the photosensitive layer and have the silicone rubber layer for improving the Adhesion between two layers or for suppression a poisoning effect on the in the composition  for the ink-repellent layer existing Kataly sator.

In addition, a protective layer (or a coating film) on the surface of the ink repellent Layer are applied. The protective layer can gebil det by laminating a transparent film, such as B. a polyethylene, polypropylene, Polyvinylchlo chloride, polyvinylidene chloride, polyvinyl alcohol, polyethyl lenterephthalate or cellophane film, on the printing ink repellent layer or by coating the ink repellent layer with a polymer that is selected from the group of the abovementioned polymeric compounds. These films can be used in the oriented form the. In addition, these films can be frosted to the Adhesion under vacuum to an original film in one print frame during exposure.

The dry PS plate according to the invention is characterized by a Original slide (transparent) imagewise exposed and then developed with a developer who is a partial or complete dissolution or swelling of the lichtemp sensitive resin layer on the image area (or image free area) can effect.

The developer used in the invention may be one of those who work as dry-PS developers Plates are known to preferred examples thereof ge However, you can hear water or aqueous solutions, respectively Water as the main component and a water-soluble organi contain beautiful solvent. The concentration of what water-soluble organic solvent is expedient less than 40% by weight, if that is the security and Considers flammability of the same. The pictorial exposed dry PS plate is particularly preferred developed pure water. Among the well-known developers, which can be used according to the invention belong to  For example, those which aliphatic hydrocarbons, such as hexane, heptane, "Isopar E, H, G" (trade name for ali phatic hydrocarbons available from the company Esso Chemical Company), gasoline and kerosene; aromatic Hydrocarbons such as toluene and xylene; halogenated Koh such as trichlorethylene, to which the be added to the following polar solvent or wel the polar solvents themselves contain:

• - Alcohols, such as methanol, ethanol, propanol, isopropa nol, benzyl alcohol, ethylene glycol monomethyl ether, 2-eth oxyethanol, diethylene glycol monoethyl ether, diethylene glycol colmonohexyl ether, triethylene glycol monomethyl ether, propy glycol monoethyl ether, dipropylene glycol monomethyl ether, Polyethylene glycol monomethyl ether, polypropylene glycol and tetraethylene;
• Ketones, such as acetone and methyl ethyl ketone;
• Esters, such as ethyl acetate, methyl lactate, butyl lactate, Propylene glycol monomethyl ether acetate, diethylene glycol acetate and diethyl phthalate; and
• Other polar solvents, such as triethyl phosphate and Tricresyl.

In addition, it is also possible as a developer such to be used, which are obtained by adding water to the above developers, the organic solutions contain medium; Developers, the above or ganic solvents contained in solubili water have been characterized by using a solubilization by, for. B. a surface-active agent; this Ent which also contains an alkaline agent such as Natri carbonate, diethanolamine and / or sodium hydroxide, contain; or water, such as tap water, pure water or distilled water.  

The developer may contain a dye such as Crystal Violet (C. I. 42555), Victoria Pure Blue (C.I. 42595) or Astrazon Red (C.I. 48020) may be added to simultaneously control the image output sections of the developed dry PS plate.

Development can be accomplished in any known manner be guided, for example by rubbing the plates Surface with a development pad (tampon), the containing the above-mentioned developer, or by casting the developer on the disk surface and connect rubbing the surface with a development brush in Water. The temperature of the developer used can However, it is preferably in in the range of 10 to 50 ° C. In this way, the Silicone rubber layer (or the ink repellent Layer) on the image area, the lichtempfindli Thus layer is exposed and serves as an ink on taking section.

The developer contains a dye, so that the frei put on image section (photosensitive layer) stained can be used to confirm the image forming property th the PS plate thus obtained or for testing the Plate. If the developer used is not a dye for staining the exposed image portion is the PS plate after development with a dyeing solution treated. The image section is with a Färbelö sung soft pad gently rubbed, so that only the exposed portion of the photosensitive Layer is stained, and thereby it can be confirmed whether the bright image area has been sufficiently developed or not. The dyeing solution used is For example, those that are obtained by Dissolving or dispersing at least one dye, selected from the group consisting of water-soluble Disperse dyes, acid dyes and basic color  substances, such as water, alcohols, Ketones, ethers or a mixture thereof. It is also effective, the staining solution carboxylic acids, amines, surfaces Active Agents, Dyeing Aids and / or An tischaumbildner add to improve the coloring Verver like the solution.

The resulting stained with such a dyeing solution lithographic printing plate is preferably water washed and dried to the problem of stickiness to eliminate the plate surface and thus the To improve the handling properties of the plate.

When these plates thus produced are stored in stacks In addition, preferably, an intermediate sheet zwi between adjacent plates to protect them.

A series of the above processes, d. H. the development lungs, staining, water washing and drying processes, are preferably in an automatic treatment direction. Preferred examples of such au Automatic treatment devices are for example in JP KOKAI No. Hei 2-220,061.

Herge from the dry PS plate according to the invention presented dry lithographic printing plate exhibits one excellent resistance to background contamination tion and excellent print durability and they has a much improved resistance to delamination solution of the silicone rubber layer at the edge sections as a result of the evacuation that occurred during pictorial Be which is insufficient Exposure at the margins of an original film leads.

The present invention will be described below with reference to FIG Be closer to the following embodiments  wrote and in practice by the invention he targeted effects are also compared with the Ver the same examples discussed in detail.

Examples 1 to 10 and Comparative Examples 1 to 3 Primer layer

An aluminum plate according to JIS A 1050 having a thickness of 0.3 mm, which has been degreased in the usual way, was immersed in a 1% aqueous solution of N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane and then at Room tempera ture dried. A primer solution having the composition shown below was applied to the aluminum plate in an amount of 4 g / m ² (weighed after drying) and dried, and cured by heating at 140 ° C for 2 minutes.

Primer solution

component Quantity (parts by weight) Sanprene 1B1700D (30% solution of a terminal hydroxyl-containing thermoplastic polyurethane resin in methyl ethyl ketone available from Sanyo Chemical Industries, Ltd.) 10 Hexafluorophosphate of a polycondensate of p-diazodiphenylamine with paraformaldehyde 0.1 TiO ₂ 0.1 Defenser MCF 323 (30% solution of a fluorine atom-containing nonionic surfactant in methyl isobutyl ketone available from Dainippon Ink and Chemicals Inc.) 0.03 Propylenglycolmethylätheracetat 50 methyl 20 pure water 1

Then the applied primer layer was used A Vacuum Exposure Device FT261V UDNS UL TRA-PLUS FLIPTOP PLATE MAKER (available from Nu Arc Company) over 20 counts.

Photosensitive layer

A photopolymerizable photosensitive solution having the following composition was applied to the aluminum plate provided with a primer layer in an amount of 4 g / m ² (weighed after drying), and then dried by heating at 100 ° C for 1 minute ,

Photosensitive solution

component Quantity (parts by weight) Polyurethane resin [isophorone diisocyanate / polyester (adipic acid / 1,4-butanediol / 2,2-dimethylpropane-1,3-diol) / isophorone diamine] 1.5 CH ₂ = CHCOO- (C ₂ H ₄ O) ₁₄ -COCH = CH ₂ 0.5 Xylylenediamine / glycidyl methacrylate (molar ratio 1: 4) adduct 1.3 Ethyl Michler's ketone 0.35 2-Chlorothioxanton 0.10 Naphthalene sulfonate from Victoria Pure Blue BOH 0.01 Defenser MCF 323 (30% solution of a fluorine atom-containing nonionic surfactant in methyl isobutyl ketone available from Dainippon Ink and Chemicals Inc.) 0.03 methyl ethyl ketone 10 Propylenglycolmethyläther 25

Silicone rubber layer

Then, a composition for the silicone rubber layer having the composition shown below was applied to the above-mentioned photopolymerizable photosensitive layer in an amount of 2.0 g / m ² (weighed after drying) and then dried at 140 ° C for 2 minutes. to obtain a cured silicone rubber layer.

Composition for the silicone rubber layer

component Quantity (parts by weight) Polysiloxanes as base polymers, each having a chain length k (number of repeating units) as indicated in Table I: CH ₂ = CH- (Si (CH ₃ ) ₂ -O) _k -Si (CH ₃ ) ₂ -CH = CH ₂ 9 (Total quantity) Hydrogenpolysiloxane as crosslinking agent whose copolymerized chain lengths m, n are given in Table I: @ (CH ₃ ) ₃ -SiO- (SiH (CH ₃ ) -O) _m -Si (CH ₃ ) ₂ -O) _n -Si (CH ₃ ) ₃ (the amount of the hydrogenpolysiloxane to be added was determined so that the amount of Si-H groups were 10 times that of the vinyl groups of the alkylene polysiloxane) X Polydimethylsiloxane (degree of polymerization about 8000) 0.5 Olefin-chloroplatinic (IV) acid 0.2 retarder 0.3 Isopar G (available from ESSO Chemical Company) 140

A biaxially oriented, one-sided matted polypropylene lenfilm with a thickness of 9 microns and the ability to Improve adhesion under vacuum to an original film, was applied to the aluminum plate Silicone rubber layer laminated so that a not  matt surface with the silicone rubber layer in Contact came under formation of a dry PS plate.

Table I

A positive film (size 450 mm x 300 mm, thickness 100 μm), a halftone dot pattern of 200 lines / 2.54 cm (1 inch) wore on each of these PS plates (size 600 mm × 450 mm), then the whole thing was using a Vacuum exposure device FT261V UDNS ULTRA-PLUS FLIP TOP PLATE MAKER (available from Nu Arc Company) Over 30 counters (counts) exposed and laminated Movie was deducted.

Each plate was immersed in water at 35 ° C while she was rubbed with a development pad to the Silicon rubber layer on the non-image area ent distant, followed by a dyeing solution with the colored according to the following composition, wherein a dry lithographic printing plate was obtained.

staining solution

component Parts by weight) crystal violet 0.1 Diethylenglycolmonomethyläther 15 pure water 85

Then each plate was placed on a lithographic offset Printing press, from which the moistening water Feeder was removed, and there were Printing operations performed using one commercially available black ink for a dry lithographic printing plate to the number of obtained to evaluate acceptable copies (the print durability) until the silicone rubber layer on the non-image area broke and the pressure plate a corresponding behind basic contamination as well as a replacement of the silicone rubber layer (on the edge of the film) caused as a result of a Pressure change at the margins of the original film, which resulted from incomplete exposure. The way  results obtained are summarized in Table II summarizes.

Table II

The results given in Table II indicate clear that the inventive dry lithographic Pressure plate excellent resistance to Hin background contamination and excellent pressure retention availability and a good film edge quality.

Example 11 Primer layer

On an aluminum plate according to JIS A 1050 having a thickness of 0.24 mm, which had been degreased and treated with a silicate in the usual manner, the same primer layer as that used in Examples 1 to 10 was used 3 g / m ² (weighed after drying) and dried and cured by heating at 130 ° C for 2 minutes. Thereafter, the thus-applied primer layer was exposed in the same manner as in Examples 1 to 10 to cure it.

Photosensitive layer

A photopolymerizable photosensitive solution with the composition given below was applied to the Aluminum plate on which a primer layer is provided was, in an amount of 3 g / m² (weighed after drying) applied and then by heating at 120 ° C for 1 minute dried.

Photosensitive solution Silicone rubber layer

Then, a composition for the silicone rubber layer having the composition shown below was applied to the above-mentioned photopolymerizable photosensitive layer in an amount of 1.8 g / m ² (weighed after drying), and then dried at 140 ° C for 2 minutes. to obtain a cured silicone rubber layer.

Composition for the silicone rubber layer

component Quantity (parts by weight) the following polysiloxanes as base polymers: CH₂ = CH- (Si (CH₃) ₂-O) _k -Si (CH₃) ₂-CH = CH₂ @ k = 500 8th k = 700 1 the following hydrogenpolysiloxane as crosslinking agent: @ (CH₃) ₃SiO- (SiH (CH₃) -O) ₈-Si (CH₃) ₃ 0.4 Polydimethylsiloxane (degree of polymerization about 8000) 0.5 (CH₃) ₃SiO- (Si (CH₃) ₂-O _p -Si (CH₃) (CH₂CH (CH₃) -C₆H₅) -O) _q -Si (CH₃) ₃; p / q = 75/25; MG = about 2 × 10⁴ 0.05 Olefin-chloroplatinic (IV) acid 0.1 retarder 0.3 Isopar G (available from ESSO Chemical Company) 100

A biaxially oriented, one-sided matted polyethy lenterephthalate film with a thickness of 6 μm and the Fä ability to improve adhesion under vacuum has been on the silicone applied to the aluminum plate rubber layer laminated so that its non-mat surface with the silicone rubber layer in Kon came to a dry PS plate was obtained.

In the same manner as in Examples 1 to 10 was imagewise exposing the resulting dry PS plate, developed and stained, using a dry litho received graphic printing plate, and there were Druckopera performed on the properties of the printing plate to rate. The following results were obtained th:

Resistance to background contamination: Rating A Printing durability: 150,000 copies Film edge: Rating A

Claims (7)

Anspruch [en] A presensitized plate for use in producing a lithographic printing plate which does not require dampening water, characterized by a substrate provided with in the order named a photosensitive layer and a silicone rubber layer, the silicone rubber layer being a layer formed is by an addition reaction of the following components (a) and (b):

• a) a mixture of polysiloxanes which serve as base polymers, each having in the molecule at least two alkenyl groups which are bonded directly to silicon atoms, and groups of the general formula: - (Si (R ¹ ) (R ² ) - O) _k - (wherein R ¹ and R ² each represent an alkyl, aryl, aralkyl, vinyl or halogenated hydrocarbon group, with the proviso that at least 70% of these groups R ¹ and R ^{2 are} methyl groups), wherein the mixture contains (i) 50 to 95% by weight of the polysiloxane whose average number k of recurring units is within the range of 100 to 500, and (ii) 5 to 50% by weight of the polysiloxane, the average number k of which is recurring Units in the range of 700 to 10,000 are ((i) + (ii = 100 wt%) and
• b) a hydrogenpolysiloxane of the following general formula: R³-Si (R⁴) ₂-O- (SiH (R⁴) -O) _m - (Si (R⁴) ₂-O) _n -Si (R⁴) ₂-R³ (I ) (wherein R ³ represents a hydrogen atom or a methyl group; R ⁴ represents an alkyl, aryl, aralkyl or vinyl groups, with the proviso that a plurality of Grup groups R ³ or a plurality of the groups R ^{4 are} the same or may be different and at least 70% of the radicals R ^{4 are} methyl groups, where m + n = 4 to 100 and n / m = 0 to 1).

2. Vorsensibilisierte plate according to claim 1, characterized in that the mixing ratio zwi the polysiloxane (i) and the polysiloxane (ii) in the Range from 70: 30 to 90: 10. 3. Presensitized plate after at least one of Claims 1 to 2, characterized in that the Mi ratio between the hydrogenpolysiloxane (b) and the polysiloxane (a) is set so that the amount of the former (b) in the range of 4 to 15 equivalents is expressed by the amount of Si-H groups per Unit equivalent amount of unsaturated carbon Carbon groups of the base polymers (a). The presensitized plate according to any one of claims 1 to 3, characterized in that the silicone rubber layer further comprises or contains a silicon atom-containing compound represented by the following general formula: (R⁵) ₃-SiO- (Si (R⁵) ₂-O) _p - (Si (R⁶) (R⁷) -O) _q -Si (R⁵) ₃ (II) in which the radicals R ^{5 may be the} same or different and each represent an alkyl group having 1 to 4 Koh lenstoffatomen ; R ⁶ and R ^{7 may be the} same or different and each represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic group, with the proviso that at least one of R ⁶ and R ^{7 represents} a substituted or unsubstituted aromatic group ; and wherein the molar ratio p / q is in the range of 99/1 to 10/90. 5. Vorsensibilisierte plate according to at least one of claims 1 to 4, characterized in that the Sili conkautschukschicht has a thickness in the range of 0.5 to 5 g / m ² . 6. Presensitized plate after at least one of Claims 1 to 5, characterized in that they except one on the surface of the silicone rubber layer having applied protective layer, which has been formed is by lamination of a transparent film, out selects from the group consisting of a polyethylene, Polypropylene, polyvinyl chloride, polyvinylidene chloride, Polyvinyl alcohol, polyethylene terephthalate or cello phan film, on the silicone rubber layer or by Be layers of the silicone rubber layer with a polymer, selected from the above polymeric compounds, the film being in an oriented and / or frosted Shape can be used. 7. Presensitized plate after at least one of claims 1 to 6, characterized in that the photosensitive layer is a monomer, oligomer or Macromonomer containing at least one photopolymerizable carries ethylenically unsaturated group, a polymeric Compound with a film forming ability, and a Photopolymerization initiator.