PS plates requiring no dampening water

A water-less PS plate for use in making a water-less lithographic printing plate comprises, on a substrate, a photopolymerizable light-sensitive layer and a silicone rubber layer in this order, wherein the light-sensitive layer is formed from a photopolymerizable light-sensitive composition which contains an urea bond-containing polyurethane as a binder. According to the present invention, there is obtained a water-less PS plate having good resistance to scratch and high printing durability. Moreover, the resulting light-sensitive layer does not get sticky, the light-sensitive layer of the non-image portions is not peeled off during the printing operations, and the lithographic plate shows good dyeability and plate-examination property.

BACKGROUND OF THE INVENTION 
The present invention relates to a presensitized plate requiring no 
dampening water for use in making a lithographic printing plate requiring 
no dampening water which permits printing without using any dampening 
water. 
A lithographic printing plate which permits printing operations without 
using any dampening water (hereinafter referred to as "water-less 
lithographic printing plate") can be obtained by exposing a presensitized 
plate requiring no dampening water (hereinafter referred to as "water-less 
PS plate") to light and then developing the same with a developer. A 
variety of water-less PS plates have been proposed (see, for instance, 
Japanese Patent Publication for Opposition Purpose (hereunder referred to 
as "J.P. KOKOKU") Nos. Sho 44-23042, Sho 46-16044, Sho 51-17081, Sho 
54-26923, and Sho 56-80046 and Sho 55-22781). Among them, a 
positive-working water-less PS plate in general has a light-sensitive 
layer comprising a photopolymerizable light-sensitive composition as 
described in J.P. KOKOKU Nos. Sho 54-26923 (U.S. Pat. No. 3,894,873) and 
Sho 56-23150. 
Such a photopolymerizable light-sensitive layer in general has the 
following composition: 
(1) an ethylenically unsaturated monomer or oligomer having a boiling point 
of not less than 100.degree. C.; 
(2) a photopolymerization initiator; 
(3) an optional heat polymerization inhibitor; and 
(4) an optional polymer binder or inorganic powder used as a filler for 
maintaining the shape of the resulting light-sensitive layer. 
The ethylenically unsaturated monomer or oligomer usually employed is a low 
molecular weight liquid or a solid having a low melting point and thus it 
is difficult to maintain predetermined hardness and thickness required for 
the light-sensitive layer, by simply using these ethylenically unsaturated 
monomers or oligomers. 
For this reason, a polymer which has good compatibility with the 
ethylenically unsaturated monomer or oligomer is generally added to the 
light-sensitive composition as a polymer binder. Examples of such a 
polymer binder are vinyl polymers, (meth)acrylate polymers, unvulcanized 
rubbers, polyethers, polyamides, polyesters, polyurethanes, epoxy resins, 
urea resins and alkyd resins as disclosed in J.P. KOKOKU No. Sho 56-23150. 
The inventors of this invention have conducted various studies of these 
polymers (hereunder referred to as "binder(s)") and have found out that a 
polyurethane of a polyol and a polyisocyanate is excellent as a binder and 
that the resulting water-less PS plate possessing the light-sensitive 
layer containing the binder exhibits in particular high resistance to 
scratch during plate-making processes and provides a water-less 
lithographic printing plate having high printing durability during 
printing processes. 
However, if the foregoing polyurethane is used as a binder and the 
ethylenically unsaturated monomer or oligomer is employed in an amount 
greater than a predetermined level, the resulting light-sensitive layer 
becomes sticky and hence the problem of adhesion of the light-sensitive 
layer to rollers during plate-making processes arises. In addition, if the 
foregoing polyurethane is employed as a binder, various drawbacks arise. 
For instance, the adhesion of non-exposed portions of the light-sensitive 
layer to a substrate becomes insufficient, the light-sensitive layer of 
the non-exposed portions is peeled off during printing processes and, as a 
result, uneven image blinding occurs due to the difference in ink 
receptivities between the light-sensitive layer of the non-exposed areas 
and the substrate. 
On the other hand, the plate-making process for water-less PS plates in 
general requires a step (step for checking the resulting plate) for dyeing 
the light-sensitive layer (so-called image portions) exposed through a 
development processing and for inspecting the dyed images in order to 
detect and/or confirm the reproduction of fine half-tone dots and the 
presence or absence of pinhole-like defects on the silicone rubber layer, 
but if this checking step is applied to the light-sensitive layer 
comprising the foregoing polyurethane as a binder, a sufficient density of 
the dye cannot be obtained. 
SUMMARY OF THE INVENTION 
Accordingly, a primary object of the present invention is to provide a 
water-less PS plate which is excellent in resistance to scratch during the 
plate-making processes and which can provide a water-less lithographic 
printing plate having good printing durability. 
A second object of the present invention is to provide a water-less PS 
plate whose light-sensitive layer does not become sticky and which can 
provide a water-less lithographic printing plate whose light-sensitive 
layer of non-exposed portions is not peeled off. 
A third object of the present invention is to provide a water-less PS plate 
excellent in plate-examination property through dyeing. 
The inventors of this invention have conducted various studies and have 
found out that the foregoing objects can be attained by the use of a 
specific polyurethane as a binder for the light-sensitive layer of a 
water-less PS plate. The present invention has been completed based on 
this finding. 
Namely, according to the present invention, there is provided a water-less 
PS plate for use in making a water-less lithographic printing plate which 
comprises, on a substrate, a light-sensitive layer and a silicone rubber 
layer, in this order, the light-sensitive layer comprising a 
photopolymerizable light-sensitive composition containing an urea 
bond-containing polyurethane as a binder. 
DETAILED EXPLANATION OF THE INVENTION 
The water-less PS plate of the present invention will hereinafter be 
described in more detail. 
The substrate used for the water-less PS plate of the present invention 
must have flexibility which is sufficient for the plate to set on the 
usual printing press and must withstand the load applied during printing 
operations. For this reason, typical examples thereof are coated paper, 
metal plates such as an aluminum plate, plastic films such as a 
polyethylene terephthalate film or a composite substrate thereof. 
A primer layer or the like can optionally be provided on the surface of the 
substrate for the purposes of forming a uniform light-sensitive layer 
thereon and of improving the adhesion between the light-sensitive layer 
and the substrate. Examples of the materials for such primer layers are 
those containing epoxy resins as disclosed in J.P. KOKOKU No. Sho 
61-54219, urethane resins, phenol resins, acrylic resins, alkyd resins, 
polyesters, polyamides and melamine resins. Moreover, the primer layer may 
be formed by photohardening a composition similar to the light-sensitive 
composition. The primer layer may further comprise additives such as dyes 
and pigments in order to prevent halation and for other various purposes. 
The light-sensitive composition used in the present invention is a 
photopolymerizable light-sensitive composition containing an urea 
bond-containing polyurethane as a binder and in general has the following 
composition: 
(1) an ethylenically unsaturated monomer or oligomer having a boiling point 
of not less than 100.degree. C.; 
(2) a photopolymerization initiator; 
(3) an optional heat polymerization inhibitor; and 
(4) an urea bond-containing polyurethane as a polymer binder. 
Examples of the ethylenically unsaturated monomers usable in the present 
invention include (meth)acrylates of alcohols such as methanol, ethanol, 
propanol, hexanol, octanol, cyclohexanol, ethylene glycol, propylene 
glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 
glycerin, trimethylol propane and pentaerythritol; reaction products of 
glycidyl (meth)acrylates with amines such as methylamine, ethylamine, 
butylamine, benzylamine, ethylenediamine, diethylenetriamine, 
hexamethylenediamine, xylylenediamine, ethanolamine, dimethylamine, 
diethylamine, diethanolamine and aniline; reaction products of glycidyl 
(meth)acrylates with carboxylic acids such as acetic acid, propionic acid, 
benzoic acid, (meth)acrylic acids, succinic acid, maleic acid, phthalic 
acid, tartaric acid and citric acid; and amide derivatives such as 
(meth)acrylamides, N-methylolacrylamide, methylenebisacrylamide and 
diacetoneacrylamide. 
The foregoing ethylenically unsaturated monomers and oligomers can be used 
alone or as a combination of at least two of them and the amount thereof 
suitably ranges from 20 to 90% by weight and preferably 30 to 70% by 
weight on the basis of the total weight of the light-sensitive layer. 
Examples of the photopolymerization initiators usable in the present 
invention are benzophenone and derivatives thereof such as 
bis(dialkylamino)benzophenone; benzoin and derivatives thereof such as 
benzoin alkyl ethers; and aromatic carbonyl compounds such as 9-acridone, 
thioxanthone, 2-chlorothioxanthone and N-methyl-9-acridone. These 
photopolymerization initiators may be used alone or as a combination 
thereof and the amount thereof used suitably ranges from 1 to 20% by 
weight, preferably 5 to 15% by weight on the basis of the total weight of 
the light-sensitive layer. 
Examples of the polymerization inhibitors employed in the light-sensitive 
composition are hydroquinone and derivatives thereof; phenol derivatives; 
nitro-substituted benzene; and tertiary aminopheno-thiazine and 
derivatives thereof. 
The urea bond-containing polyurethane used in the present invention may be 
any polyurethanes so far as they contain urea bonds in the molecule, but 
preferably those having ester bonds and/or ether bonds in the molecule in 
addition to the urea bonds. The urea bond-containing polyurethane used in 
the present invention can be prepared by reacting a diisocyanate compound 
represented by the following general formula (I), with a diol compound 
represented by the following general formula (II) and a diamine compound 
represented by the following general formula (III): 
Diisocyanate Compounds: 
EQU OCN--R.sub.1 --NCO (I) 
wherein R.sub.1 represents a divalent aliphatic or aromatic hydrocarbon 
coupling group which may be substituted by alkyl, aralkyl, aryl and/or 
alkoxy groups and/or halogen atoms. 
Diol Compounds: 
EQU HO--R.sub.2 --OH (II) 
wherein R.sub.2 represents a divalent aliphatic or aromatic hydrocarbon 
coupling group which may be substituted by alkyl, aralkyl, aryl and/or 
alkoxy groups and/or halogen atoms and which may optionally comprise an 
ester or ether bond in the molecule. 
Diamine Compounds: 
EQU H.sub.2 N--R.sub.3 --NH.sub.2 (III) 
wherein R.sub.3 represents a divalent aliphatic or aromatic hydrocarbon 
coupling group which may be substituted by alkyl, aralkyl, aryl and/or 
alkoxy groups and/or halogen atoms. 
Specific examples of the diisocyanate compounds represented by Formula (I) 
include the following compounds, but the present invention is not 
restricted to these specific examples: 
2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, p-xylylenediisocyanate, 
m-xylylenediisocyanate, 4,4'-diphenylmethanedi-isocyanate, 
1,5-naphthylenediisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 
hexamethylenediisocyanate, isophoronediisocyanate and 4,4'-methylenebis 
(cyclohexylisocyanate). 
These diisocyanate compounds may be used alone or as a combination of two 
or more of them. 
Specific examples of the diol compounds represented by Formula (II) include 
the following compounds, but the present invention is not restricted to 
these specific examples: 
ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 
polyethylene glycol, polypropylene glycol, neopentyl glycol, 
1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, hydrogenated bisphenol A, 
ethylene oxide adducts of hydrogenated bisphenol A, and polyester diols 
such as copolymers of adipic acid with propylene glycol and copolymers of 
adipic acid with ethylene glycol and 1,4-butanediol. 
These diol compounds may be used alone or as a combination of two or more 
of them. 
Particularly preferred diol compounds are the foregoing polyester diols (in 
particular, those having a molecular weight ranging from 1,000 to 3,000) 
and polyether diols (for instance, polyethylene glycol and polypropylene 
glycol, preferably those having a molecular weight ranging from 1,000 to 
10,000) and thus polyurethanes having a urea bond and an ester and/or 
ether bond which are preferred embodiments of the present invention can be 
obtained. In this case, it is particularly preferred to simultaneously use 
the foregoing polyether diol and/or polyester diol and low molecular 
weight diols such as ethylene glycol, diethylene glycol, triethylene 
glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,3-butanediol 
and/or 1,6-hexanediol. 
Specific examples of the amine compounds represented by Formula (III) 
include the following compounds, but the present invention is not 
restricted to these specific examples and these amine compounds may be 
used alone or as a combination of two or more of them: 
ethylenediamine, 1,4-tetramethylenediamine, 1,6-hexamethylene-diamine, 
isophoronediamine, m-xylylenediamine, p-xylylenediamine, 
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether and 
4,4'-methylenebis(2-chloroaniline). Among them, preferred are 
ethylenediamine, 1,4-tetramethylenediamine, 1,6-hexamethylene-diamine and 
isophoronediamine. 
The urea bond-containing polyurethanes used in the present invention can in 
general be prepared by heating a mixture of the foregoing diisocyanate, 
diol compound and diamine compound in an aprotic solvent in the presence 
of a known catalyst having activity selected depending on the reactivity 
of these components, but preferably they are prepared by first reacting 
the diisocyanate compound with the diol compound to form a prepolymer and 
then reacting the prepolymer with the diamine compound. 
In the foregoing preparation of the polyurethane, the molar ratio of the 
sum of the diol compound and the amine compound to the diisocyanate 
compound preferably ranges from 0.8:1 to 1.2:1. If an isocyanate group 
remains at a terminus of the polymer after the reaction, the polymer is 
treated with alcohols, amines or water so that an isocyanate group does 
not remain in the polymer. The molar ratio of the diol compound to the 
diamine compound preferably ranges from 0.1:0.9 to 0.9:0.1 and more 
preferably 0.2:0.8 to 0.8:0.2. 
The molecular weight of the urea bond-containing polyurethane used in the 
present invention is not less than 5,000 and preferably 10,000 to 200,000 
expressed in the weight average molecular weight. 
The weight ratio of the urea bond-containing polyurethane to the 
ethylenically unsaturated monomer or oligomer in the light-sensitive 
composition used in the present invention ranges from 1:0.1 to 1:5 and 
preferably 1:0.2 to 1:2. 
The light-sensitive composition used in the present invention may comprise 
a variety of plasticizers for various purposes such as improvement in the 
developability and the control of physical properties of the resulting 
photohardenable light-sensitive layer. 
The thickness of the light-sensitive layer explained above is not critical, 
but it is desirably limited to the range of from 1 to 10.mu. from the 
viewpoint of uniformity of the resulting film and from economical point of 
view. 
The silicone rubber layer preferably used in the present invention is 
formed from a linear or partially cross-linked poly-diorganosiloxane which 
comprises the following repeating units: 
##STR1## 
wherein R'.sub.s represent a monovalent group selected from the group 
consisting of alkyl, aryl, alkenyl groups and combination thereof, which 
may be substituted with functional groups such as halogen atoms, amino 
groups, hydroxyl group, alkoxy groups, aryloxy groups, (meth)acryloxy 
groups and/or thiol groups. The silicone rubber layer may optionally 
comprise other additives such as fine powder of inorganic substances (for 
instance, silica, calcium carbonate and titanium oxide); auxiliary agents 
for adhesives (for instance, siliane coupling agents, titanate type 
coupling agents and aluminum type coupling agents); and 
photopolymerization initiators. 
The silicone rubber layer can be obtained by crosslinking a polysiloxane 
having functional groups at the termini and a molecular weight ranging 
from several thousands to several hundreds of thousands as a starting 
material for the polymer (silicone rubber) having the foregoing 
polysiloxane as a principal skeleton according to the method as will be 
described below. More specifically, the crosslinking method comprises 
mixing the foregoing polysiloxane having, for instance, a hydroxyl group 
on either or both termini thereof with a silane type crosslinking agent 
represented by the following general formula and then heating the mixture 
or condensing and hardening the mixture at ordinary temperature optionally 
in the presence of a catalyst such as an organometal compound (e.g., an 
organotin compound), an inorganic acid or an amine: 
EQU R.sub.n SiX.sub.4-n 
wherein n is an integer ranging from 1 to 3; R is the same as that defined 
above; X represents --OH, --OR.sup.1, --OAc, --O--N.dbd.CR.sup.1 R.sup.2, 
--Cl, --Br or --I; R.sup.1 and R.sup.2 are the same as those defined above 
and may be the same or different; and Ac represents an acetyl group. 
Alternatively, the foregoing polysiloxane and a polyvalent hydrogen 
organopolysiloxane crosslinking agent are condensed and hardened 
optionally in the presence of the foregoing silane type crosslinking 
agent. 
Moreover, it is also effective to use addition-type silicone rubber layer 
which is crosslinked through an addition reaction of an.fwdarw.SiH group 
with a CH.sub.2 .dbd.CH-- group. The addition-type silicone rubber is 
resistive to the influence of humidity during the hardening operation, can 
be crosslinked at a high speed, and can easily provide a silicone rubber 
layer having desired physical properties after the crosslinking operation. 
The addition-type silicone rubber layer used herein can be obtained 
through a reaction of a polyvalent hydrogen organopolysiloxane with a 
polysiloxane compound having at least two CH.sub.2 .dbd.CH-- bonds per 
molecule and preferably obtained by hardening and crosslinking a 
composition comprising the following components: 
(1) 100 parts by weight of an organopolysiloxane having at least two 
alkenyl groups (more preferably vinyl groups) which are directly bonded to 
silicon atoms in a molecule; 
(2) 0.1 to 1,000 parts by weight of an organo hydrogen polysiloxane having 
at least two.fwdarw.SiH bonds in one molecule; and 
(3) 0.00001 to 10 parts by weight of a catalyst for the addition reaction. 
The alkenyl groups of the component (1) may be present at either the middle 
or the ends of the molecular chain and the component may have an organic 
group other than the alkenyl groups, such as substituted or unsubstituted 
alkyl and/or aryl groups. The component (1) may optionally comprise a 
small amount of hydroxyl groups. The component (2) can react with the 
component (1) to form a silicone rubber layer and it further serves to 
improve the adhesion between the silicone rubber layer and the 
light-sensitive layer. The hydroxyl groups of the component (2) may exist 
at either the middle or the ends of the molecular chain and the component 
(2) may have an organic group other than the hydroxyl groups, such as 
those listed above in connection with the component (1). At least 60% of 
the total organic groups of the components (1) and (2) is preferably a 
methyl group from the viewpoint of improvement in ink repellency of the 
resulting silicone rubber layer. The molecular structures of the 
components (1) and (2) may be either of linear, cyclic and branched ones. 
Moreover, the molecular weight of either one of them is preferably not 
less than 1,000 from the viewpoint of the physical properties of the 
resulting silicone rubber layer and more preferably that of the component 
(1) should be not less than 1,000. 
Examples of the component (1) are .alpha., .omega.-divinyl 
polydimethylsiloxane and (methylvinylsiloxane) (dimethylsiloxane) 
copolymers having methyl groups at both ends; and examples of the 
component (2) are polydimethylsiloxane having methyl groups at both ends, 
.alpha., .omega.-dimethyl-poly(methyl hydrogen siloxane), (methyl hydrogen 
siloxane)(dimethyl siloxane) copolymers having methyl groups at both ends 
and cyclic poly(methyl hydrogen siloxane). 
The catalyst for addition reaction (component (3)) may freely be selected 
from known ones, but is preferably platinum type compounds such as 
elemental platinum, platinum chloride, chloroplatinic acid and platinum 
coordinated with olefins. The composition for forming silicone rubber 
layer may further comprise crosslinking-inhibiting agents such as vinyl 
group-containing organopolysiloxanes (e.g., tetracyclo(methylvinyl) 
siloxane), carbon-carbon triple bond-containing alcohols, acetone, methyl 
ethyl ketone, methanol, ethanol and propylene glycol monomethyl ether. 
The composition initiates an addition reaction immediately after the mixing 
of these three components and the hardening speed thereof rapidly 
increases in proportion to the increase in the reaction temperature. 
Therefore, the pot life of the composition must be extended and the time 
required for the composition to be hardened on the light-sensitive layer 
must be reduced. For these reasons and for achieving stable adhesion 
between the light-sensitive layer and the rubber layer, the composition 
should be hardened at a temperature at which properties of the substrate 
and the light-sensitive layer do not cause any change and it should be 
maintained at that high temperature till it is completely hardened. 
In addition to the foregoing components, the composition may further 
comprise known adhesion imparting agents such as alkenyl trialkoxy silane; 
hydroxyl group-containing organopolysiloxanes which are components for 
condensation-type silicone rubber layers; hydrolyzable functional 
group-containing silanes (or siloxanes); and known fillers such as silica 
for improving the strength of the resulting rubber layer. 
In the present invention, the silicone rubber layer serves as an ink 
repellent layer. If it is too thin, the ink repellency of the resulting 
layer is lowered and defects are easily formed, while if it is too thick, 
the developability of the resulting PS plate is impaired. Therefore, the 
thickness thereof preferably ranges from 0.5 to 5 .mu.m. 
The water-less PS plate explained above may further comprise various 
silicone rubber layers applied onto the foregoing silicone rubber layer 
and it may also comprise an adhesive layer between the light-sensitive 
layer and the silicone rubber layer for the purposes of enhancing the 
adhesion therebetween and of preventing the poisoning of the catalyst 
present in the silicone rubber composition. To protect the surface of the 
silicone rubber layer, a transparent film may be laminated on the silicone 
rubber layer or a polymer coating may be applied thereto. Examples of such 
films or polymer coatings are polyethylene, polypropylene, polyvinyl 
chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene 
terephthalate and cellophane films. 
The water-less PS plate of the present invention is first exposed to light 
through an original and then developed with a developer capable of 
dissolving a part of the light-sensitive layer of the image portions or of 
swelling a part or whole thereof, or of swelling the silicone rubber 
layer. In this case, a part of the light-sensitive layer of the image 
portions and the silicone rubber layer thereof are removed, or only the 
silicone rubber layer of the image portions is removed, either of which is 
encountered depending on the strength of the developer used. 
As the developers used in the present invention, any known developers for 
water-less PS plates can be employed. Examples thereof include aliphatic 
hydrocarbons such as hexane, heptane, "Isopar E, H, G" (trade names of 
aliphatic hydrocarbons available from ESSO CHEMICAL CO., LTD.), gasoline, 
kerosine, aromatic hydrocarbons such as toluene and xylene, and 
halogenated hydrocarbons such as trichlene, to which at least one polar 
solvent listed below is added. 
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. 
The development is performed, for instance, by rubbing the surface of the 
plate with a pad for development containing such a developer to thus 
remove the silicone rubber layer of the image portions whereby the 
light-sensitive layer is exposed and the exposed light-sensitive layer 
serves as ink receiving portions. 
Alternatively, it is also possible to adopt a method for development as 
disclosed in J. P. KOKOKU No. Sho 63-33140, which method comprises 
dissolving out a part or whole of the light-sensitive layer of the images 
with a processing solution capable of dissolving at least part of the 
light-sensitive layer of the images and then rubbing the surface of the 
plate in the presence of water which does not swell the silicone rubber 
layer or a solvent mainly comprising water, to thus remove the silicone 
rubber layer of the images. 
To confirm the image-forming ability of the resulting lithographic printing 
plate, the plate-checking process is performed by dyeing the exposed image 
portions (the light-sensitive layer) with a dyeing solution. Only the 
exposed image portions of the light-sensitive layer are dyed by lightly 
rubbing the image portions with a soft pad soaked with the dyeing 
solution. Thus, it can be confirmed whether even the highlight portions 
are sufficiently developed or not. As such a dyeing solution, there may be 
used, for instance, those obtained by dissolving at least one member 
selected from the group consisting of water-soluble disperse dyes, acid 
dyes and basic dyes in a solvent such as water, alcohols, ketones, ethers 
or mixture thereof. It is also effective to add carboxylic acids, amines, 
surfactants and/or auxiliary dyeing agents to the dyeing solution in order 
to enhance the dyeing ability of the solution. 
Since the light-sensitive layer of the water-less PS plate of the present 
invention contains an urea bond-containing polyurethane as a binder, the 
water-less lithographic plate obtained by exposing to light and developing 
the PS plate has good resistance to scratch and high printing durability. 
Moreover, the resulting light-sensitive layer does not get sticky, the 
light-sensitive layer of the non-image portions is not peeled off during 
the printing operations, and the light-sensitive layer of images shows 
good dyeability and plate-examination properties.

EXAMPLE 
The present invention will hereunder be explained in more detail with 
reference to the following non-limitative working Examples and Preparation 
Examples and the effects practically achieved by the present invention 
will also be discussed in detail in comparison with Comparative Examples. 
PREATION EXAMPLE 1 
200 Parts by weight of a commercially available polyester (ODX-105: adipic 
acid/ethylene glycol/1,4-butanediol=1/0.5/0.5 (molar ratio); available 
from DAINIPPON INK AND CHEMICALS, INC.), 18 parts by weight of 
1,4-butanediol and 112.2 parts by weight of isophorone diisocyanate were 
dissolved in 1458.4 parts by weight of dimethylacetamide and the addition 
polymerization of these monomers was performed at 100.degree. C. for 2 
hours in the presence of dilauric acid-n-butyl tin as a catalyst in the 
usual manner. Moreover, 34.5 parts by weight of isophoronediamine as a 
chain extender was added to the polymerized mixture and the reaction was 
continued for additional one hour at 100.degree. C. to complete the 
reaction. The composition of the urea bond-containing polyurethane resin 
is detailed in the following Table I (see Example 1; expressed as charge 
stock ratio (molar ratio)). Separately, the urea bond-containing 
polyurethanes used in Examples 2 and 3 were also prepared in the same 
manner as used above. Further, the binders used in Comparative Examples 1 
and 2 were also prepared according to the first step of the foregoing 
method for the preparation of the polyurethanes. 
EXAMPLES 1 TO 3 AND COMATIVE EXAMPLES 1 TO 2 
A titanium white dispersion having the following composition was applied 
onto the surface of a smooth aluminum plate, which had been degreased in 
the usual manner, with a bar coater and heated at 200.degree. C. for 20 
minutes to form a primer layer. The coated amount of the primer layer was 
2.0 g/m.sup.2 (weighed after drying). 
______________________________________ 
Titanium White Dispersion 
Amount 
Component (part by weight) 
______________________________________ 
Epoxy resin (Epikote 1007; available 
10 
from SHELL OIL CO., LTD) 
TiO.sub.2 powder (TIPAQUE R-782; available 
1 
from ISHIHARA SANGYO CO., LTD.) 
Ethyl cellosolve acetate 
40 
Ethyl cellosolve 40 
Butyl cellosolve 20 
______________________________________ 
Five kinds of photopolymerizable light-sensitive compositions having the 
following compositions were prepared using five kinds of binders having 
the charge stock ratios shown in Table I and they were applied onto the 
surface of these five aluminum plates, to which the foregoing primer layer 
had been applied, in an amount of 4.0 g/m.sup.2 (on dry basis) to thus 
form light-sensitive layers. 
______________________________________ 
Photopolymerizable Light-sensitive Layer 
Amount (part 
Component by weight) 
______________________________________ 
Polyurethane urea or polyester 
7.5 
urethane having a charge stock 
ratio shown in Table I 
(a 20% by weight solution in 
dimethylacetamide) 
Michler's ketone 0.16 
2-Chloro-thioxanthone 0.05 
2-Chloro-N-butyl-acridone 0.17 
Reaction product of m-xylylenediamine 
0.9 
with glycidyl methacrylate 
(molar ratio: 1:4) 
CH.sub.2 .dbd.CHCOO(CH.sub.2 CH.sub.2 O).sub.4 COCH.dbd.CH.sub.2 
0.6 
Victoria Pure Blue NPS (available 
0.01 
from HODOGAYA CHEMICAL CO., LTD.) 
Defenser MCF 323 (available from 
0.005 
DAINIPPON INK AND CHEMICALS, INC.) 
Methyl ethyl ketone 5.0 
Propylene glycol monomethyl ether 
35.0 
______________________________________ 
The surface of these five light-sensitive layers thus prepared were lightly 
pressed with a finger and examined on whether the finger marks were left 
thereon or not. The results thus obtained are summarized in Table I. 
A silicone rubber composition having the following composition was applied 
onto each light-sensitive layer of these five water-less PS plates in an 
amount of 2.0 g/m.sup.2 (on dry basis) to thus form hardened silicone 
rubber layer. 
______________________________________ 
Silicone Rubber Composition 
Amount 
Component (part by weight) 
______________________________________ 
Dimethylpolysiloxane having hydroxyl 
90 
groups on both ends (molecular 
weight = about 70,000) 
Methyl triacetoxysilane 
3 
Dibutyl-tin-dioctanoate 
1 
Isopar G (available from Exxon 
140 
Chemical Co., Ltd.) 
______________________________________ 
An OPP (biaxially oriented polypropylene) film having a thickness of 9 
.mu.m, one surface of which had been matted, was laminated on each 
silicone rubber layer of the water-less PS plates prepared above to thus 
obtain water-less PS plates of Examples 1 to 3 and Comparative Examples 1 
and 2. 
A positive film was put on each of the foregoing of waterless PS plates, 
brought into close contact with one another in vacuo, the resulting 
assembly was imagewise exposed to light with the usual exposure machine, 
the laminated OPP film was peeled off and the exposed plate was immersed 
in polypropylene glycol (molecular weight 200) maintained at 40.degree. C. 
for one minute. After the immersion, the processing solution remaining on 
the plate surface and the back side thereof was removed with a squeegee of 
rubber. Then the plate was lightly rubbed with a pad, while spraying tap 
water thereon, to peel off the silicone rubber layer of the image 
portions. Subsequently, the plate was dyed with a dyeing solution having 
the following composition and the dyeing density of the image portions 
(solid portions) was examined with a reflection densitometer (Macbeth RD 
920). The results obtained are listed in Table I given below. 
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Dyeing Solution 
Amount (part 
Component by weight) 
______________________________________ 
Crystal Violet 0.1 
Carbitol 14.0 
Pionine D-310 (polyoxyethylene 
0.5 
octylphenyl ether HLB: 13.6; available 
from Takemoto Oil & Fats Co., Ltd.) 
New coal B4SN (available from 
1.8 
NIPPON EMULSIFYING AGENT CO., LTD.): 
##STR2## 
(n = 4.2) 
Pure water 83.1 
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The water-less lithographic printing plate thus obtained was fitted to 
KOMORI LITHRONE 26 Printing Press, of which the device for supplying 
dampening water was dismantled, and printing operation was performed with 
Aqualess V-G Sumi Ink (available from Toyo Ink Manufacturing Co., Ltd.) to 
thus give 10,000 printed matters. Thereafter, the printing plate was 
examined on whether the light-sensitive layer of the images wore out or 
not. The results thus observed are listed in Table I. 
TABLE I 
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Example No. Ex. 1 Ex. 2 Ex. 3 Comp.1 Comp.2 
______________________________________ 
(i) Charge Stock 
Molar Ratio 
Isophorone- 1 1 1 1 l 
diisocyanate 
ODX-105 0.2 0.2 0.2 0.2 0.5 
1,4-Butanediol 
0.4 0.8 
Ethylene glycol 0.4 0.5 
Ethylenediamine 0.4 
Isophoronediamine 
0.4 0.8 
(ii) Evaluation 
Finger Marks on 
none none none formed formed 
the Surface 
of the Light- 
sensitive Layer 
Dyeing Density 
1.43 1.43 1.45 1.03 1.36 
on the Images 
Wear on the Light 
none none none none observed 
sensitive observed 
Layer after 10,000 
Printing 
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EXAMPLE 4 
An aluminum plate, to which a primer layer was applied in the same manner 
as in Examples 1 to 3, was prepared. Separately, a binder having the 
charge stock ratio (molar ratio) defined below was prepared in the same 
manner as in Preparation Example 1, and a light-sensitive solution 
containing the photopolymerizable light-sensitive composition having the 
following formulation and containing the binder was prepared. The 
light-sensitive solution was applied onto the surface of the aluminum 
plate in an amount of 4.0 g/m.sup.2 (on dry basis). 
______________________________________ 
Light-sensitive Solution 
Amount (part 
Component by weight) 
______________________________________ 
Isophoronediisocyanate/EG 6000* 
12.04 
/1,4-butanediol/isophoronediamine 
polyurethane urea (charge stock ratio 
= 1.0/0.2/0.4/0.4; MEK solution: 
(12.46% by weight)) 
Ethyl Michler's ketone 0.14 
2-Chloro-thioxanthone 0.10 
Reaction product of 0.9 
m-xylylenediamine with glycidyl 
methacrylate (molar ratio = 1:4) 
CH.sub.2 .dbd.CHCOO(CH.sub.2 CH.sub.2 O).sub.4 COCH.dbd.CH.sub.2 
0.6 
Victoria Pure Blue NPS (available 
0.01 
from HODOGAYA CHEMICAL CO., LTD.) 
Defenser MCF 323 (available from 
0.005 
DAINIPPON INK AND CHEMICALS, INC.) 
Methyl ethyl ketone 5.0 
Propylene glycol monomethyl ether 
35.0 
______________________________________ 
*Polyethylene glycol (molecular weight: 7,500; available from WAKO PURE 
CHEMICALS, INC.). 
Even when the surface of the resulting light-sensitive layer was lightly 
pressed with a finger, it did not get sticky and no finger mark was left 
or observed. 
The same silicone rubber composition as used in Examples 1 to 3 was applied 
onto the foregoing light-sensitive layer so that the coated amount thereof 
was 2.0 g/m.sup.2 (on dry basis) and then dried to form a hardened 
silicone rubber layer. 
An OPP (biaxially oriented polypropylene) film having a thickness of 9 
.mu.m, one surface of which had been matted was laminated on the silicone 
rubber layer of the water-less PS plates prepared above to thus obtain a 
water-less PS plate. 
A water-less lithographic printing plate was prepared from the water-less 
PS plate thus obtained in the same manner as in Examples 1 to 3. 
The dyeing density of the resulting lithographic plate was examined and it 
was found to be 1.39. 
10,000 copies were prepared using the water-less lithographic printing 
plate thus obtained under the same conditions as in Examples 1 to 3, then 
the degree of wear of the light-sensitive layer on the images was examined 
and it was confirmed that any wear was not observed.