PS plate for use in making lithographic printing plate requiring no dampening water

The present invention relates to a presensitized plate for use in making a lithographic plate requiring no dampening water and comprising, on a support, a light-sensitive resin layer and a silicone rubber layer, in this order, wherein the silicone rubber layer is crosslinked by addition reaction of an .fwdarw.SiH group with a --CH.dbd.CH-- group and wherein the light-sensitive resin layer comprises: (1) a monomer or oligomer having at least one photopolymerizable or photo-crosslinkable and olefinically unsaturated double bond, (2) an organic solvent-soluble polyurethane resin having a glass transition temperature of 20.degree. C. or below and being capable of forming a film, and (3) a photopolymerization initiator. According to the present invention, the PS plate has excellent image-forming properties and printing properties.

The present invention relates to a presensitized plate (PS plate) for use 
in making a lithographic printing plate which makes it possible to perform 
printing without using any dampening water. 
Various kinds of presensitized plates for use in making lithographic 
printing plates which permit printing operation without using any 
dampening water (hereunder referred to as "water-less PS plate") have been 
known. In particular, those which comprise, on a substrate, a 
light-sensitive resin layer and a silicone rubber layer in this order show 
quite an excellent quality. Examples of such water-less PS plates are 
disclosed in, for instance, U.S. Pat. No. 3,894,873 and British Patent No. 
1,419,643. 
The silicone rubber layers commonly employed in these water-less PS plates 
are those obtained by partially crosslinking with a crosslinking agent, a 
high molecular weight polymer having a polysiloxane as a principal 
skeleton. On the other hand, the light-sensitive resin layers for 
positive-working water-less PS plates include photopolymerizable 
light-sensitive layer, a photodimerizable light-sensitive resin layer or a 
diazo-type light-sensitive resin layer, which can be cured through 
exposure to light. 
The water-less PS plate having such a layer structure is generally 
processed as follows, to form images. Namely, the water-less PS plate is 
exposed to light to cure the lightsensitive resin layer and, if necessary, 
to cause photoadhesion of the layer to the upper silicone rubber layer at 
their boundary, whereby both layers are firmly united. As a result, the 
permeation of a developer and the accompanying dissolution of the 
light-sensitive resin layer through the silicone rubber layer can be 
prevented and thus non-image areas composed of the silicone rubber layer 
are formed. On the other hand, image areas can be formed by penetrating a 
developer through the silicone rubber layer to dissolve out a part or 
whole of the unhardened light-sensitive layer and then removing the 
silicone rubber layer which remains on the unhardened light-sensitive 
layer by means of a physical force. It is important for obtaining an 
excellent image-forming ability that the silicone rubber layer is firmly 
adhered to the light-sensitive resin layer to prevent removal of the 
non-image area during the development or in the course of the subsequent 
printing. Various light-sensitive resin layers suitable for this purpose 
have been proposed. For example, when an allyl methacrylate copolymer 
described in DE 3811832A is used as a binder, the adhesion of the 
photopolymerizable light-sensitive resin layer with the silicone rubber 
layer placed thereon can be secured to a certain extent and excellent 
image-forming properties can be obtained by suitably selecting the 
composition of the silicone rubber layer. 
However, the allyl methacrylate copolymers have problems that their glass 
transition temperature is high, that the photo-cured light-sensitive resin 
layer is rigid and fragile, and that such a layer has poor printing 
properties. 
SUMMARY OF THE INVENTION 
The object of the present invention is, therefore, to provide a water-less 
PS plate having excellent image-forming properties and printing 
properties. 
After intensive investigations made for the purpose of attaining the 
above-described object, the inventors have found out that a water-less PS 
plate having both of the above-described properties and comprising, on a 
support, a light-sensitive resin layer and a silicone rubber layer, in 
this order, can be obtained by incorporating into the light-sensitive 
layer, an organic solvent-soluble polyurethane resin having a glass 
transition temperature of 20.degree. C. or below and being capable of 
forming a film, as a binder. The present invention has been completed on 
the basis of this finding. 
Namely, the present invention relates to a presensitized plate for use in 
making a lithographic plate requiring no dampening water and comprising, 
on a support, a light-sensitive resin layer and a silicone rubber layer, 
in this order, said rubber layer being crosslinked by addition reaction of 
an .fwdarw.SiH group with a --CH.dbd.CH-- group, wherein said 
light-sensitive resin layer comprises the following components: 
(1) a monomer or oligomer having at least one photopolymerizable or 
photo-crosslinkable and olefinically unsaturated double bond, 
(2) an organic solvent-soluble polyurethane resin having a glass transition 
temperature of 20.degree. C. or below and being capable of forming a film, 
and 
(3) a photopolymerization initiator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The water-less PS plate of the present invention is required to have a 
flexibility high enough to enable the plate to be mounted on an ordinary 
lithographic press, as well as a strength high enough to withstand load 
applied thereto during the printing. Typical examples of the substrates 
are, therefore, coated paper, metal plate such as aluminum plate, plastic 
films such as polyethylene terephthalate film, rubber and the composite 
substrates thereof. The substrate can be coated with a coating such as a 
primer layer in order to prevent halation or for another purpose. 
A variety of primer layers can be employed in the present invention for the 
purposes of enhancing the adhesion between the substrate and the 
light-sensitive resin layer, of preventing halation, of coloring the 
resulting images, and of improving printing properties of the resulting 
lithographic printing plate. As such primer layers, there may be 
mentioned, for instance, those obtained by exposing a variety of 
light-sensitive polymers to light to cure, prior to the lamination of the 
light-sensitive resin layer, as disclosed in Japanese Patent Un-examined 
Published Application (hereunder referred to as "J. P. KOKAI") No. Sho 
60-2290; those obtained by heatsetting an epoxy resin as disclosed in J. 
P. KOKAI No. Sho 62-50760; those prepared by hardening a gelatin film as 
disclosed in U.S. Pat. No. 4,861,698; and those obtained by hardening a 
casein film. In addition, the primer layer may further comprise at least 
one polymer having a glass transition point of not more than room 
temperature such as polyurethanes, polyamides, styrene/butadiene rubbers, 
carboxy-modified styrene/butadiene rubbers, acrylonitrile/butadiene 
rubbers, carboxylic acid-modified acrylonitrile/butadiene rubbers, 
polyisoprenes, acrylate rubbers, polyethylenes, chlorinated polyethylenes 
and chlorinated polypropylenes, in order to make the primer layer 
flexible. The amount thereof to be added to the primer layer is not 
critical so far as the formation of the primer layer is ensured. Moreover, 
the primer layer may comprise other additives, for instance, dyes, pH 
indicators, agents or compositions for obtaining a visible image 
immediately after exposure to light, photopolymerization initiators, 
adhesive aids (such as polymerizable monomers, diazo resins, silane 
coupling agents, titanate coupling agents or aluminum coupling agents), 
white pigments and silica powder for achieving the foregoing purposes. The 
amount of the primer layer to be coated in general ranges from 2 to 20 
g/m.sup.2 (determined after drying). 
The light-sensitive resin layer usable in the present invention comprises 
(1) a monomer or oligomer having at least one photopolymerizable or 
photo-crosslinkable and olefinically unsaturated double bond, (2) an 
organic solvent-soluble polyurethane resin having a glass transition 
temperature of 20.degree. C. or below and being capable of forming film, 
and (3) a photopolymerization initiator. If necessary, (4) another polymer 
compound capable of forming a film and soluble in an organic solvent can 
be also incorporated thereinto. 
COMPONENT (1) 
Monomer or oligomer having at least one photopolymerizable or 
photo-crosslinkable and olefinically unsaturated double bond 
The monomers and oligomers usable in the present invention include, for 
example, monofunctional acrylates and methacrylates such as polyethylene 
glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, 
phenoxyethyl(meth)acrylate, 2-(meth)acryloxyethyl hydrogen phthalate and 
2-(meth)acryloxyethyl hydrogen succinate; polyethylene glycol 
di(meth)acrylate, trimethylolethane tri(meth)acrylate, neopentyl glycol 
di(meth)acrylate, pentaerythritol tri-(meth)acrylate, pentaerythritol 
tetra(meth)acrylate, dipenta-erythritol hexa(meth)acrylate, hexanediol 
di(meth)acrylate, trimethylolpropane tri(acryloyloxypropyl) ether, 
tri-acryloyloxyethyl) isocyanurate, calcium (meth)acrylate, sodium 
(meth)acrylate, and compounds produced by adding ethylene oxide or 
propylene oxide to a polyfunctional alcohol such as glycerol or 
trimethylolethane and then converting the product into its (meth)acrylate; 
urethane acrylates described in Japanese Patent Publication for Opposition 
Purpose (hereunder referred to as "J. P. KOKOKU") Nos. 48-41708 and 
50-6034 and J. P. KOKAI No. 51-37193; polyester acrylates described in J. 
P. KOKAI No. 48-64183 and J. P. KOKOKU Nos. 49-43191 and 52-30490; 
polyfunctional acrylates and methacrylates such as epoxy acrylates 
prepared by reacting an epoxy resin with (meth)acrylic acid; and 
N-methylol-acrylamide derivatives described in U.S. Pat. No. 4540649. 
Further, photocurable monomers and oligomers described on pages 300 to 308 
of Journal of the Adhesion Society of Japan, Vol. 20, No. 7 (1984) are 
also usable. Other compounds usable in the present invention include 
reaction products of an isocyanate having an allyl group such as allyl 
isocyanate or 
##STR1## 
with a hydroxyl group-containing (meth)acrylate compound such as 
hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, polyethylene 
glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, 
pentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, 
CH.sub.2 .dbd.C(R)COOCH.sub.2 CH(OH)CH.sub.20 O CH.sub.2 
.dbd.C(R)COOCH.sub.2 CH(OH)CH.sub.2 O--CH.sub.2 CH(OH)CH.sub.2 
--O--CH.sub.2 CH(OH)CH.sub.2 OOCC(R).dbd.CH.sub.2, CH.sub.2 
.dbd.C(R)COO--CH.sub.2 CH(OH)CH.sub.2 --O--C.sub.2 H.sub.4 O--CH.sub.2 C 
H(OH)CH.sub.2 OOCC(R).dbd.CH.sub.2, CH.sub.2 .dbd.C(R)COO--CH.sub.2 
CH(OH)CH.sub.2 -O--CH.sub.2 CH(CH.sub.3)--OCH.sub.2 CH(OH)CH.sub.2 
OOCC(R).dbd.CH.sub.2, 
##STR2## 
wherein R represents a hydrogen atom or a methyl group; reaction products 
of a glycidyl ether having an allyl group such as allyl glycidyl ether 
with a (meth)acrylate compound having a carboxylic acid group such as 
(meth)acrylic acid, (meth)acryloxyethyl hydrogen phthalate, (meth)acryloxy 
ethyl hydrogen succinate, (meth)acryloxyethyl hydrogen 
maleate,(meth)acryloxyethyl hydrogen tetrahydrophthalate or 
(meth)acryloxyethyl hydrogen hexahydrophthalate; and reaction products of 
an alcohol having an allyl group such as allyl alcohol or 2-allyloxyethyl 
alcohol with the above-described (meth)acrylate compound having a 
carboxylic acid group or its acid chloride group. 
COMPONENT (2) 
Organic solvent-soluble polyurethane resin having a glass transition 
temperature of 20.degree. C. or below and being capable of forming a film 
The above-described polyurethane resins usable in the present invention 
include those prepared by reacting a diisocyanate with a diol, for 
example, in substantially equimolar amounts. The diisocyanates include, 
for example, toluene diisocyanate, xylylene diisocyanate, diphenylmethane 
diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 
diphenyl ether diisocyanate, hydrogenated xylylene diisocyanate, 
cyclohexane diisocyanate, hydrogenated diphenylmethane diisocyanate, 
tetramethylxylene diisocyanate and lysine diisocyanate. 
The diols include, for example, polypropylene glycol, polyethylene glycol, 
polytetramethylene glycol, ethylene oxide/propylene oxide copolymer, 
tetrahydrofuran/ethylene oxide copolymer, tetrahydrofuran/propylene oxide 
copolymer, polyesterdiols (such as polyethylene adipate, polydiethylene 
adipate, polypropylene adipate, polyhexamethylene adipate, polyneopentyl 
adipate, polyhexamethylene-neopentyl adipate, polyethylene diethylene 
adipate and polyethylene hexamethylene adipate), 
poly-.epsilon.-caprolactonediol, polyhexamethylene carbonatediol and 
polytetramethylene adipate. Branched polyurethane resins are also usable. 
They include compounds formed by replacing a part of or the entire 
diisocyanate with a trifunctional or higher functional isocyanate compound 
(such as an adduct of 1 mole of trimethylolpropane with 3 moles of 
2,4-toluene diisocyanate; undecane triisocyanate, dicycloheptane 
triisocyanate or 1,8-diisocyanate-4-isocyanatomethyloctane) and by 
simultaneously replacing a part of the diol component with a 
monofunctional monoalcohol [such as allyl alcohol, allyloxyethyl alcohol, 
hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, 
polypropylene glycol (meth)acrylate, hydroxypropyl mono(meth)acrylate, 
benzyl alcohol or ethyl alcohol] to introduce a functional group therein. 
Further, polyurethane resins having a diol component comprising a special 
functional group such as an alkyldialkanolamine, (meth)acrylate 
group-containing diol or a carboxylic acid group-containing diol are also 
usable. Particularly, a polyurethane resin soluble in an aqueous alkali 
solution can be obtained by using a diol having a carboxylic acid group as 
described in J. P. KOKAI Nos. 63-287942 or 63-287943. Such a polyurethane 
resin is preferred when a water-soluble developer is used. 
The polyurethane resin (2) is generally used in an amount of 15.about.90% 
by weight, preferably 30.about.80% by weight, based on the total weight of 
the light-sensitive resin layer. 
COMPONENT (3) 
Photopolymerization initiator 
The photopolymerization initiators usable in the present invention include, 
for example, vicinal polyketaldonyl compounds disclosed in U.S. Pat. No. 
2,367,660, .alpha.-carbonyl compounds disclosed in U.S. Pat. Nos. 
2,367,661 and 2,367,670, acyloin ethers disclosed in U.S. Pat. No. 
2,448,828, aromatic acyloin compounds substituted with an 
.alpha.-hydrocarbon group and disclosed in U.S. Pat. No. 2,722,512, 
polynuclear quinone compounds disclosed in U.S. Pat. Nos. 3,046,127 and 
2,951,758, a combination of a triaryl imidazole dimer and p-aminophenyl 
ketone, as disclosed in U.S. Pat. No. 3,549,367, benzothiazole type 
compounds disclosed in U.S. Pat. No. 3,870,524, benzothiazole type 
compound/trihalomethyl-s-triazine type compound, as disclosed in U.S. Pat. 
No. 4,239,850, acridine and phenazine compounds disclosed in U.S. Pat. No. 
3,751,259, oxadiazole compounds disclosed in U.S. Pat. No. 4,212,970, 
trihalomethyl-s-triazine type compounds having a chromophoric group 
disclosed in U.S. Pat. No. 3,954,475, J. P. KOKAI No. 53-133428, U.S. Pat. 
No. 4,189,323, J. P. KOKAI Nos. 60-105667 and 62-58241 and Japanese Patent 
Application No. 61- 227489, and peroxyester compounds containing a 
benzophenone group disclosed in J. P. KOKAI Nos. 59-197401 and 60-76503. 
The amount of the photopolymerization initiator used is 0.1 to 20% by 
weight, preferably 1 to 10% by weight, based on the total light-sensitive 
resin layer. 
COMPONENT (4) 
Other polymeric compounds capable of forming a film and other than the 
component (2) 
The other polymeric compounds capable of forming a film and soluble in an 
organic solvent which are used, if necessary, in the present invention 
include, for example, methacrylic acid copolymers, acrylic acid 
copolymers, crotonic acid copolymers, maleic acid copolymers, partially 
esterified maleic acid copolymers, acidic cellulose derivatives, polyvinyl 
pyrrolidone, polyethylene oxide, alcohol-soluble nylon, polyesters, 
unsaturated polyesters, polystyrene, epoxy resin, phenoxy resin, polyvinyl 
butyral, polyvinyl formal, polyvinyl chloride, polyvinyl alcohol, 
partially acetalized polyvinyl alcohol, water-soluble nylon, gelatin and 
water-soluble cellulose derivatives. 
The polymeric compounds having a photopolymerizable or photo-crosslinkable 
and olefinically unsaturated double bond at a side chain include, for 
example, allyl (meth)acrylate/(meth)acrylic acid/optional another 
addition-polymerizable vinyl monomer copolymers and alkali metal salts or 
amine salts thereof, as described in J. P. KOKAI No. 59-53836; reaction 
products of a hydroxyethyl (meth)acrylate/(meth)acrylic acid/alkyl 
(meth)acrylate copolymer or alkali metal salts or amine salts thereof with 
(meth)acryloyl chloride, as described in J. P. KOKOKU No. 59-45979; 
reaction products obtained by adding pentaerythritol triacrylate to a 
maleic anhydride copolymer by half-esterification or alkali metal salts or 
amine salts thereof; reaction products obtained by adding a 
monohydroxyalkyl (meth)acrylate, polyethylene glycol mono(meth)acrylate or 
polypropylene glycol mono(meth)acrylate to a styrene/maleic anhydride 
copolymer by half-esterification or alkali metal salts or amine salts 
thereof; reaction products of a part of a carboxylic acid of a 
(meth)acrylic acid copolymer or crotonic acid copolymer with glycidyl 
(meth)acrylate or alkali metal salts or amine salts thereof, reaction 
products of a hydroxyalkyl (meth)acrylate copolymer, polyvinyl formal or 
polyvinyl butyral with maleic anhydride or itaconic anhydride and alkali 
metal salts or amine salts thereof, reaction products of a hydroxyalkyl 
(meth)acrylate/(meth)acrylic acid copolymer with 2,4-tolylene 
diisocyanate/hydroxyalkyl (meth)acrylate (1/1) adduct and alkali metal 
salts or amine salts thereof; (meth)acrylic acid copolymers partially 
reacted with allyl glycidyl ether and alkali metal salts or amine salts 
thereof, as described in J. P. KOKAI No. 59-53836; vinyl 
(meth)acrylate/(meth)acrylic acid copolymer and alkali metal salts or 
amine salts thereof; allyl (meth)acrylate/sodium styrenesulfonate 
copolymer; vinyl (meth)acrylate/sodium styrenesulfonate copolymer; allyl 
(meth)acrylate/sodium acrylamido-1,1-dimethylethylenesulfonate copolymer, 
vinyl (meth)acrylate/sodium acrylamido-1,1-dimethylethylenesulfonate, 
2-allyloxyethyl methacrylate/methacrylic acid copolymer and 
2-allyloxyethyl methacrylate/2-methacryloxyethyl hydrogen succinate 
copolymer. 
The weight ratio of the total of the polymers (2) and (4) to the monomer or 
abigom (1) is preferably in the range of 99:1 to 30:70, more preferably 
97:3 to 50:50. 
OTHER COMPONENTS OF THE LIGHT-SENSITIVE RESIN LAYER 
The light-sensitive resin layer preferably contains a heat polymerization 
inhibitor such as hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, 
pyrogallol, t-butylcatechol, benzoquinone, 
4,4'-thiobis(3-methyl-6-t-butylphenol),2,2'-methylenebis(4-methyl-6-t-buty 
lphenol) and 2-mercapto-benzimidazole. If necessary, a dye or pigment for 
coloring the light-sensitive resin layer, and a pH indicator or leuco dye 
as an agent or composition for obtaining a visible image immediately after 
imagewise exposure may be incorporated in the light-sensitive resin layer. 
Further, this resin layer may contain a small amount of a silicone 
compound such as polydimethylsiloxane, methylstyrene-modified 
polydimethylsiloxane, olefin-modified polydimethylsiloxane, 
polyether-modified polydimethylsiloxane, silane coupling agent, silicone 
diacrylate and silicone dimethacrylate. This resin layer may contain a 
fluorine-containing surfactant or fluorine containing surface-orientating 
agent which improves its coating properties. This layer may contain also a 
diazo resin capable of improving the adhesion of the light-sensitive resin 
layer to the primer layer. The amount of these additives is usually not 
more than 10% by weight based on the total light-sensitive resin layer. 
The layer may contain not more than 50% by weight, based on the total 
light-sensitive resin layer, of a silica powder or hydrophobic silica 
powder having a surface treated with a silane coupling agent having a 
(meth)acryloyl group or aryl group. 
The components explained in the above are dissolved in a suitable solvent 
such as 2-methoxyethanol, 2-methoxyethyl acetate, methyl lactate, ethyl 
lactate, propylene glycol monomethyl ether, methanol, ethanol, methyl 
ethyl ketone, water or a suitable mixture of them, and then the solution 
is applied to the surface of the substrate in an amount of about 0.1 to 10 
g/m.sup.2, preferably 0.5 to 5 g/m.sup.2 (on dry basis). 
The silicone rubber layer usable in the present invention and wherein the 
crosslinking is made by additionreacting an .fwdarw.SiH group with a 
--CH.dbd.CH-- group is those obtained by reacting a polyvalent hydrogen 
organopolysiloxane with a polysiloxane compound having two or more 
--CH.dbd.CH-- bonds in a molecule. It is produced preferably by curing and 
crosslinking a composition comprising the following components: 
(1) 100 parts by weight of an organopolysiloxane having at least two 
alkenyl groups (preferably vinyl groups) directly bonded to silicon atoms 
in a molecule, 
(2) 0.1 to 1000 parts by weight of an organohydrogen polysiloxane having at 
least two .fwdarw.SiH bonds in a molecule, and 
(3) 0.00001 to 10 parts by weight of an addition catalyst. 
The alkenyl group of Component (1) may be at any position of the chain such 
as its end or its middle position. The organic group other than the 
alkenyl group includes substituted or unsubstituted alkyl and aryl groups. 
Component (1) may contain a very small amount of a hydroxyl group. 
Component (2) forms a silicone rubber layer by its reaction with Component 
(1) and it also serves as an adhesive for the light-sensitive layer. The 
hydrogen group of the .fwdarw.SiH group of Component (2) may be at any 
position such as its end or middle position in the chain. The organic 
group other than such a hydrogen atom is the same as that of Component 
(1). It is preferable from the viewpoint of the ink repellency that at 
least 60 % of the organic groups of Components (1) and (2) comprise methyl 
groups. The molecular structures of Components (1) and (2) may have 
linear, cyclic or branched molecular structure. It is preferable from the 
viewpoint of the physical properties of the rubber that at least one of 
Components (1) and (2) has a molecular weight of higher than 1,000 and 
that particularly the molecular weight of Component (1) exceeds 1,000. 
Examples of Component (1) include .alpha.,.omega.-divinylpolydimethyl 
siloxane and methylvinylsiloxane/dimethylsiloxane copolymer having methyl 
groups at both ends thereof. Examples of Component (2) include 
polydimethylsiloxane having hydrogen atoms at both ends thereof, 
.alpha.,.omega.-dimethylpolymethylhydrogen siloxane, methylhydrogen 
siloxane/dimethylsiloxane copolymer having methyl groups at both ends 
thereof and cyclic polymethylhydrogensiloxane. 
The addition catalyst (3) is selected from known ones. Particularly, 
platinum type compounds are preferred. Examples of such platinum type 
compounds include metal platinum, platinum chloride, chloroplatinic acid 
and platinum coordinated with olefins. The composition for obtaining a 
silicone rubber layer may further comprise a crosslinking inhibitor such 
as a vinyl group-containing organopolysiloxane, for instance, 
tetracyclo(methylvinyl) siloxane, a C-C triple bond-containing alcohol, 
acetone, methyl ethyl ketone, methanol, ethanol and propylene glycol 
monomethyl ether, for the purpose of controlling the curing rate of the 
composition. 
The addition reaction takes place and curing is initiated as soon as these 
three components are admixed together. The curing rate rapidly increases 
as the reaction temperature is elevated. Therefore, the composition is 
preferably maintained at a temperature at which the properties of the 
substrate and the light-sensitive resin layer do not change until the 
composition is completely cured, for the purposes of extending the pot 
life of the composition and of shortening the time required for curing the 
composition on the light-sensitive resin layer. This can further provide 
highly stable adhesion between the resulting silicone rubber layer and the 
light-sensitive resin layer. 
The composition for the silicone rubber layer may optionally comprise, in 
addition to the foregoing components, known agents for imparting adhesive 
properties to the silicone rubber layer such as alkenyl trialkoxysilanes; 
hydroxyl group-containing organopolysiloxanes which are components of 
condensation type silicone rubber layers; and/or hydrolyzable functional 
group-containing silanes (or siloxanes). The composition may also comprise 
known fillers such as silica for enhancing the strength of the resulting 
silicone rubber layer. 
After plate-making processes, the silicone rubber layer of the water-less 
PS plate of the present invention serves as an ink repellent layer. 
Therefore, if the silicone rubber layer is too thin, the ink repellency 
thereof becomes low and the layer is liable to be injured, while if it is 
too thick, the developability of the resulting water-less PS plate is 
impaired. Thus, the thickness of the silicone rubber layer preferably 
ranges form 0.5 to 5 .mu.m. 
The addition type silicone rubber layer to be used in the present invention 
has merits that it is scarcely influenced by humidity during curing, that 
it can be crosslinked at a high speed, and that intended properties can be 
easily obtained. Even when the light-sensitive resin layer contains a 
carboxylic acid, the addition type silicone rubber layer is sufficiently 
cured, while the curing of a condensation type silicone rubber layer is 
inhibited by the crosslinking agent in such a case. Since the 
light-sensitive resin layer can contain the carboxylic acid, the 
development with a developer mainly comprising water or an aqueous alkali 
solution is possible and the designing of the light-sensitive printing 
plate is easy. 
Various additional silicone rubber layers can be formed on the silicone 
rubber layer of the present water-less PS plate. A bonding layer can be 
formed between the light-sensitive resin layer and the silicone rubber 
layer, in order to increase the adhesion between the light-sensitive layer 
and the silicone rubber layer and to prevent poisoning of the catalyst in 
the silicone rubber composition. To protect the surface of the silicone 
rubber layer, the silicone rubber layer may be laminated with a 
transparent film such as polyethylene, polypropylene, polyvinyl chloride, 
polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate or 
cellophane, or it may be coated with a polymer. 
The water-less PS plate of the present invention is exposed through a 
transparent original and then the image area (unexposed area) is developed 
with a developer capable of dissolving or swelling a part or the whole of 
the light-sensitive resin layer or a developer capable of swelling the 
silicone rubber layer. In this step, both the light-sensitive resin layer 
and the silicone rubber layer of the image area are removed or, 
alternatively, only the silicone rubber layer of the image area is 
removed. Either way may be selected depending on the strength of the 
developer. 
The developers usable in the present invention are those known as the 
developers for the water-less PS plates. They include, for example, 
aliphatic hydrocarbons such as hexane, heptane, `Isopar E, H or G` (trade 
names of aliphatic hydrocarbons of Esso Chemicals Inc.), gasoline and 
kerosene; aromatic hydrocarbons such as toluene and xylene; halogenated 
hydrocarbons such as trichloroethylene to which the following polar 
solvent is added; and the following polar solvents per se: 
Alcohols (such as methanol, ethanol, propanol, benzyl alcohol, ethylene 
glycol monophenyl ether, 2-methoxyethanol, 2-ethoxyethanol, carbitol 
monoethyl ether, carbitol monomethyl ether, triethylene glycol monoethyl 
ether, propylene glycol monomethyl ether, propylene glycol monoethyl 
ether, dipropylene glycol monomethyl ether, polyethylene glycol monomethyl 
ether, propylene glycol, polypropylene glycol, triethylene glycol and 
tetraethylene glycol), 
Ketones (such as acetone and methyl ethyl ketone), 
Esters (such as ethyl acetate, methyl lactate, ethyl lactate, butyl 
lactate, propylene glycol monomethyl ether acetate, carbitol acetate, 
dimethyl phthalate and diethyl phthalate), and 
Others (such as triethyl phosphate and tricresyl phosphate). 
It is also possible to use developers obtained by adding water to the 
foregoing organic solvent type developers and those obtained by 
solubilizing the foregoing organic solvents in water with the aid of a 
surfactant or the like, to which an alkaline agent (such as sodium 
carbonate, monoethanolamine, diethanolamine, triethanolamine, sodium 
silicate, potassium silicate, sodium hydroxide, potassium hydroxide and 
sodium borate) may be added; as well as tap water per se or an alkaline 
water per se. 
These developers may comprise a dye such as Crystal Violet or Astrazone Red 
for the simultaneous coloration of the image areas with the development. 
The development of the water-less PS plate of the present invention can be 
performed in any known manner, for instance, by rubbing the surface of the 
plate with a developing pad containing a developer or by pouring a 
developer onto the surface of the plate and then rubbing the plate surface 
with a developing brush in water. By this, the portions of both the 
silicone rubber layer and the light-sensitive resin layer are removed from 
the image areas and as a result, the surface of the substrate or the 
primer layer is exposed. In this case, the exposed portions serve as ink 
receiving parts. Alternatively, only the portions of the silicone rubber 
layer of the image areas can be removed through the foregoing development 
processing. In this case, the surface of the light-sensitive resin layer 
is exposed and hence the exposed portions likewise serve as the ink 
receiving parts. 
The water-less PS plate of the present invention is constructed as stated 
above and therefore the adhesion between the light-sensitive resin layer 
and the addition type silicone rubber layer is improved, and excellent 
image-forming properties and printability of the water-less PS plate are 
ensured. 
The following examples will further illustrate the present invention, which 
by no means limit the present invention. 
EXAMPLE 1 
A primer layer composition comprising the following components was applied, 
in an amount of 10 g/m.sup.2 (on dry basis), to a smooth JIS A 1050 
aluminum plate having a thickness of 0.3 mm which had been degreased by an 
ordinary method, and then heated at 120.degree. C. for 3 min to dry and 
cure the layer: 
__________________________________________________________________________ 
Milk casein 48 parts by weight 
40% Aqueous glyoxal solution 
5 parts by weight 
Styrene/butadiene rubber latex 
100 
parts by weight 
(solid content: 50%, Tg of film: -20.degree. C.) 
Na.sub.2 CO.sub.3 2.6 
parts by weight 
TiO.sub.2 1 parts by weight 
##STR3## 3 parts by weight 
##STR4## 1.2 
parts by weight 
Pure water 700 
parts by weight 
##STR5## 0.5 
parts by weight 
__________________________________________________________________________ 
A light-sensitive resin solution comprising the following components was 
applied, in an amount of 3 g/m.sup.2 (on dry basis), to the primer layer 
provided on the aluminum plate and then dried at 100.degree. C. for 1 min: 
______________________________________ 
Estane 5715 (polyurethane resin having 
1 part by 
Tg of -12.degree. C.; a product of Dainippon 
weight 
Ink & Chemicals, Inc.) 
Allyl methacrylate/methacrylic 
1 part by 
acid (85/15 molar %) copolymer weight 
##STR6## 0.45 part by weight 
##STR7## 0.45 part by weight 
##STR8## 0.2 part by weight 
Bromophenol Blue 0.01 part by 
(pH indicator) weight 
Defenser MCF 323 0.02 part by 
(a product of Dainippon Ink weight 
& Chemicals, Ind.) 
PF.sub.6 salt of p-diazodiphenyl- 
0.002 part by 
amine/formaldehyde condensate weight 
Propylene glycol monomethyl 
15 parts by 
ether weight 
Methyl ethyl ketone 10 parts by 
weight 
______________________________________ 
Then, 2.0 g/m.sup.2 (on dry basis) of a silicon rubber layer composition 
comprising the following components was applied to the light-sensitive 
resin layer and then dried at 140.degree. C. for 2 min to form a cured 
silicone rubber layer: 
______________________________________ 
.alpha.,.omega.-Divinylpolydimethyl- 
9 parts by weight 
siloxane (degree of 
polymerization: about 700) 
##STR9## 1 part by weight 
##STR10## 0.2 part by weight 
Polydimethylsiloxane 0.5 part by weight 
(degree of polymerization: about 8,000) 
Olefin/chloroplatinic acid 
0.2 part by weight 
Inhibitor 0.15 part by weight 
Isopar G (a product 160 part by weight 
of Esso Chemicals Inc.) 
______________________________________ 
A single-side-matted polypropylene film having a thickness of 9 .mu.m was 
laminated on the thus obtained silicone rubber layer to form a water-less 
PS plate. 
A positive film was placed on the PS plate and exposed for 30 counts, with 
FT 26 V UDNS ULTRA-PLUS FLIP-TOP PLATE MAKER (a product of Nuarc) and then 
the positive film was peeled off. 
The plate was immersed in a developer comprising 12 parts by weight of 
benzyl alcohol, 5 parts by weight of sodium isopropylnaphthalenesulfonate, 
1 part by weight of triethanolamine and 82 parts by weight of water, for 
one min and then rubbed with a developing pad to remove both the 
light-sensitive resin layer and silicone rubber layer of the unexposed 
area. Thus, the water-less PS plate, on which the image of the positive 
film was faithfully reproduced all over the surface, was prepared. 
The plate thus prepared was used for printing with Heidelberg GTO printing 
machine, of which a device for feeding dampening water had been 
dismounted, using TOYO KING ULTRA TUK aquealess G sumi Ink (a product of 
Toyo Ink Mfg. Co., Ltd.) As a result, prints having faithfully reproduced 
image and free from greasing were produced. 
EXAMPLE 2 
A light-sensitive resin layer composition comprising the following 
components was applied, in an amount of 3.0 g/m.sup.2 (on dry basis) to 
the primer layer provided on the aluminum substrate, which was the same as 
that of Example 1, and then dried at 100.degree. C. for 1 min. 
______________________________________ 
Allyl methacrylate/tetraethylene glycol 
1 part by 
monomethacrylate/2-methacryloxyethyl hydrogen 
weight 
succinate (60/30/10 mol) copolymer 
Aqueous alkali solution-soluble polyurethane 
1 part by 
resin comprising polyesterdiol (comprising 
weight 
1,6-hexanediol/neopentyl glycol/adipic acid 
and having a hydroxyl value of 60)/dimethylol- 
propionic acid/diphenylmethane diisocyanate 
(1/1/2 mol)(glass transition temperature: -7.degree. C.) 
##STR11## 0.6 part by weight 
Victoria Pure Blue BOH 0.01 part by 
weight 
Defenser MCF 323 (a product of 
0.02 part by 
Dainippon Ink & Chemicals, Inc.) 
weight 
##STR12## 0.2 part by weight 
Propylene glycol monomethyl ether 
15 parts by 
weight 
Methyl ethyl ketone 10 parts by 
weight 
______________________________________ 
Then, a silicon rubber layer composition comprising the following 
components was applied to the light-sensitive resin layer, in an amount of 
2.0 g/m.sup.2 (on dry basis), and dried at 140.degree. C. for 2 min to 
form a cured silicone rubber layer: 
______________________________________ 
Dimethylpolysiloxane having a 
9 parts by weight 
trivinyl group at both ends 
(degree of polymerization: about 1,300) 
##STR13## 1 part weight 
##STR14## 0.6 part by weight 
##STR15## 0.2 part by weight 
Olefin/chloroplatinic acid 
0.2 part by weight 
Inhibitor 0.15 part by weight 
Isopar G (a product of Esso 
160 parts by weight. 
Chemicals Inc.) 
______________________________________ 
A single-side-matted polypropylene film having a thickness of 9 .mu.m was 
laminated on the thus obtained silicone rubber layer to form a water-less 
PS plate. 
After conducting the exposure and development in the same manner as that of 
Example 1, a water-less PS plate having excellent image-forming properties 
was obtained. 
EXAMPLE 3 
A light-sensitive primer solution having the following composition was 
applied to a degreased, silicate-treated JIS A 1050 aluminum plate having 
a thickness of 0.3 mm, in an amount of 4 g/m.sup.2 (on dry basis), and 
then dried at 140.degree. C. for 5 min. 
______________________________________ 
Polyesterdiol comprising adipic 
5 parts by 
acid/1,6-hexanediol/neopentyl weight 
glycol (hydroxyl value: about 60) 
Takenate D-110 N (75% solution) 
1.5 parts by 
weight 
(CH.sub.2CHCOOCH.sub.2 ) .sub.3CC.sub.2 H.sub.5 
1 part by 
weight 
##STR16## 0.3 part by weight 
Victoria Pure Blue BOH 0.005 part by 
weight 
p-Diazodiphenylamine/ 0.02 part by 
p-formaldehyde condensate weight 
dodecylbenzenesulfonate 
Methyl ethyl ketone 30 parts by 
weight 
Propyleneglycol 30 parts by 
monomethyl ether acetate weight 
Defenser MCF 323 (a product of 
0.02 part by 
Dainippon Ink & Chemicals, Inc.) 
weight 
______________________________________ 
Then, a light-sensitive resin layer composition comprising the following 
components was applied to the primer layer on the aluminum plate in an 
amount of 3.0 g/m.sup.2 on (dry basis) and dried at 100.degree. C. for 1 
min. 
______________________________________ 
Polyurethane resin comprising polyesterdiol 
2 parts by 
(adipic acid/1,6-hexanediol/neopentyl glycol) 
weight 
and isophorone diisocyanate 
(glass transition temperature: -40.degree. C.) 
Reaction product of 1 mole of xylenediamine, 
0.6 part by 
2 moles of glycidyl methacrylate and 2 moles 
weight 
of allyl glycidyl ether 
##STR17## 0.3 part by weight 
Fluorine-containing nonionic surfactant 
0.01 part by 
weight 
##STR18## 0.2 part by weight 
Propylene glycol monomethyl ether 
15 parts by 
weight 
Methyl ethyl ketone 10 parts by 
weight 
______________________________________ 
The same silicon rubber layer composition as that used in Example 2 except 
that 
##STR19## 
was omitted and applied, in an amount of 2 g/m.sup.2 (on dry basis), to 
the light-sensitive resin layer and then dried at 140.degree. C. for 2 min 
to obtain the cured silicone rubber layer. 
A single-side-matted polyethylene terephthalate film having a thickness of 
6.5 .mu.m was laminated on the thus obtained silicone rubber layer, to 
form the water-less PS plate. 
The PS plate was exposed to light for 30 counts with the same vacuum 
exposing apparatus as that used in Example 1. Then, the positive film was 
peeled off. The plate was immersed in triethylene glycol at 30.degree. C. 
for 1 min and then rubbed with a developing pad in water to remove the 
silicone rubber layer of the unexposed part. Thus, the water-less PS on 
which the image of the positive film was faithfully reproduced all over 
the surface, was prepared.