JP2639738B2 - No fountain solution photosensitive lithographic printing plate - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a fountain solution-free photosensitive lithographic printing plate for obtaining a fountain solution-free lithographic printing plate capable of printing without using a fountain solution.

[PRIOR ART AND PROBLEMS TO BE SOLVED] A fountain-free lithographic printing plate that can be printed without using a fountain solution (hereinafter referred to as "waterless lithographic printing plate") is a lithographic printing plate requiring no fountain solution ( Hereinafter, referred to as “waterless PS plate”),
Obtained by phenomena. A number of inventions have been made in the past for the PS version without water. (For example,
44-23042, JP-B-46-16044, JP-B-51-17081
No., JP-B-54-26923, JP-B-56-80046, JP-B-55
-22781). Above all, as the positive type PS plate without water, those having a photosensitive layer made of a photopolymerizable photosensitive composition disclosed in JP-B-54-26923, JP-B-56-23150 and the like are generally used. .

Such a photopolymerizable photosensitive layer generally has the following composition.

(1) an ethylenically unsaturated monomer or oligomer having a boiling point of 100 ° C. or higher, (2) a photopolymerization initiator, (3) a thermal polymerization inhibitor if necessary, and (4) a shape retention of the photosensitive layer if necessary. Binders or inorganic powders used as fillers for

By the way, a commonly used ethylenically unsaturated monomer or oligomer is a liquid having a low molecular weight or a solid having a low melting point, and the ethylenically unsaturated monomer or oligomer alone has a certain hardness and a certain thickness as a photosensitive layer. It is difficult to maintain.

Therefore, it is customary to add a polymer having good compatibility with the ethylenically unsaturated monomer or oligomer as a polymer binder. Examples of the polymer added to the photosensitive layer include vinyl polymers, (meth) acrylate polymers, unvulcanized rubbers, polyethers, polyamides, as disclosed in JP-B-56-23150. Examples include polyester, polyurethane, epoxy resin, urea resin, and alkyd resin.

The present inventors have conducted various studies on these high-molecular polymers (hereinafter referred to as "binders"). Polyurethane, which is a polymer of a polyol and a polyisocyanate, is excellent as a binder. It was found that the process showed high printing durability.

However, when the above-mentioned polyurethane is used as a binder, when a certain amount or more of an ethylenic monomer or oligomer is used, the obtained photosensitive layer becomes sticky, and adhesion of the photosensitive layer to a roller in a manufacturing process becomes a problem. Further, when the above polyurethane is used as a binder, the adhesiveness of the unexposed portion photosensitive layer to the support becomes insufficient, and the unexposed portion photosensitive layer is peeled off in a printing process, and as a result, the unexposed portion photosensitive layer and the support are not supported. It has also been found that the difference in ink receptivity from the body directly appears in the printed matter, causing unevenness in the thickness of the printed matter.

On the other hand, in the plate making process of the waterless PS plate, the photosensitive layer (so-called image area) exposed by the development process was dyed in order to detect and confirm the reproducibility of minute dots and pinhole-shaped defects in the silicone rubber layer. Process for confirming the dyeing (plate inspection)
However, when it is used for a photosensitive layer using the above-mentioned polyurethane as a binder, there is a problem that a sufficient dyeing density cannot be obtained.

Therefore, a first object of the present invention is to provide a waterless PS plate having excellent scratch resistance in the plate making process and excellent printing durability in the printing process.

A second object of the present invention is to provide a waterless PS plate which has no stickiness of the photosensitive layer and does not peel off the photosensitive layer in an unexposed portion during a printing process.

A third object of the present invention is to provide a waterless PS plate which is excellent in dye plate inspection.

[Means for solving the problem]

The present inventors have conducted intensive studies and as a result, the above object was achieved by using a urea bond-containing polyurethane as a binder for the photosensitive layer in a waterless PS plate having a photosensitive layer and a silicone rubber layer in this order on a support. I found something to be achieved.

 Hereinafter, the present invention will be described in detail.

The support used in the waterless PS plate of the present invention must be flexible enough to be set in a normal printing press and capable of withstanding the load applied during printing. Accordingly, typical supports include coated paper, metal plates such as aluminum plates, plastic films such as polyethylene terephthalate, and composite substrates thereof. On the surface of these supports, a primer layer or the like is provided as necessary so that a photosensitive layer described below can be uniformly applied, and to improve the adhesion between the photosensitive layer and the support. Is also good.

As the primer layer, those containing an epoxy resin as shown in JP-B-61-54219, urethane resin, phenol resin, acrylic resin, alkyd resin,
Polyester, polyamide, melamine resin and the like can be used. Further, a composition obtained by photocuring a composition similar to that of the photosensitive layer may be used. These primer layers may also contain additives such as dyes and pigments for preventing halation and for other purposes.

The photosensitive layer used in the present invention is a photopolymerizable photosensitive layer using a polyurethane containing a urea bond as a binder, and generally has the following composition.

(1) Contains an ethylenically unsaturated monomer or oligomer having a boiling point of 100 ° C. or higher, (2) a photopolymerization initiator, (3) a thermal polymerization inhibitor if necessary, and (4) a urea bond used as a polymer binder. Polyurethane.

As the ethylenically unsaturated monomer, for example, the following can be used.

Alcohols (eg, methanol, ethanol, propanol, hexanol, octanol, cyclohexanol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol,
Acrylic acid or methacrylic acid esters of polyethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc.).

Amines (eg, methylamine, ethylamine,
Reaction products of butylamine, benzylamine, ethylenediamine, diethylenetriamine, hexamethylenediamine, xylenediamine, ethanolamine, dimethylamine, diethylamine, diethanolamine, aniline, etc.) with glycidyl acrylate or glycidyl methacrylate.

Reaction products of carboxylic acids (eg, acetic acid, propionic acid, benzoic acid, acrylic acid, methacrylic acid, succinic acid, maleic acid, phthalic acid, tartaric acid, citric acid, etc.) with glycidyl acrylate or glycidyl methacrylate.

Amide derivatives (for example, acrylamide, methacrylamide, N-methylolacrylamide, methylenebisacrylamide, diacetoneacrylamide, etc.).

The above ethylenically unsaturated monomers or oligomers can be used alone or in combination of two or more, and the amount thereof is 20 to 90 based on the total amount of the photosensitive layer.
% By weight is suitable and preferably selected from the range of 30 to 70% by weight.

Examples of the photopolymerization initiator include benzophenone and its derivatives (such as bis (dialkylamino) benzophenone), benzoin and its derivatives (such as benzoin alkyl ether), and aromatic carbonyl compounds (9-acridone, thioxanthone, 2-chlorothioxanthone, −
Methyl-9-acridone) and the like. These may be used alone or in combination. The amount used is suitably from 1 to 20% by weight, preferably from 5 to 15% by weight, based on the total weight of the photosensitive layer.
It is.

As the thermal polymerization inhibitor, hydroquinone and its derivatives, phenol derivatives, nitro-substituted benzene, tertiary aminophenothiazine and its derivatives are used.

As the urea bond-containing polyurethane which is a feature of the present invention, any polyurethane having a urea bond in the molecule can be used, but preferably a polyurethane having an ester bond and / or an ether bond together with a urea bond. is there. The urea bond-containing polyurethane used in the present invention is obtained by reacting a diisocyanate compound represented by the formula [I] with a diol compound represented by the formula [II] and a diamine compound represented by the formula [III]. Can be obtained by

Formula [I] OCN-R1-NCO In the formula, R1 is a divalent aliphatic or aromatic carbon which may have a substituent (eg, an alkyl group, an aralkyl group, an aryl group, an alkoxy group, a halogen atom, etc.). Represents a hydrogen linking group.

Formula [II] HO-R2-OH In the formula, R2 represents a divalent aliphatic or aromatic carbon which may have a substituent (eg, an alkyl group, an aralkyl group, an aryl group, an alkoxy group, a halogen atom, etc.). Represents a hydrogen linking group, and may contain an ester bond or an ether bond as necessary.

In the formula [III] H ₂ N—R 3 —NH ₂ , R 3 is a divalent aliphatic or a divalent aliphatic group which may have a substituent (for example, an alkyl group, an aralkyl group, an aryl group, an alkoxy group, a halogen atom and the like). Represents an aromatic hydrocarbon linking group.

As the diisocyanate compound represented by the formula (I),
Specific examples include, but are not limited to:

That is, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 3,3 '-Dimethylbiphenyl-4,4'-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate) and the like.

These diisocyanate compounds may be used alone or in combination of two or more.

Specific examples of the diol compound represented by the formula [II] include, but are not limited to, the following.

That is, ethylene glycol, diethylene glycol,
Triethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, neopentylene glycol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, hydrogenated bisphenol A, ethylene of hydrogenated bisphenol A Oxide adducts, polyester diols (for example, a copolymer of adipic acid and propylene glycol, a copolymer of adipic acid and ethylene glycol and 1,4-butanediol, and the like).

These diol compounds can be used alone or in combination of two or more.

Among the above-mentioned diol compounds, particularly preferred are the above-mentioned polyester diols (particularly, those having a molecular weight of
1000 to 3000) and polyether diols (e.g., polyethylene glycol, polypropylene glycol, etc., preferably having a molecular weight of 1,000 to 10,000). And / or a polyurethane containing an ether bond. In this case, together with the polyester diol and / or polyether diol, a low molecular weight diol, preferably an aliphatic diol having a molecular weight of 800 or less (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, 1,4 -Butanediol, 1,3-butanediol, 1,6-hexanediol, etc.) are particularly preferred.

Specific examples of the diamine compound represented by the formula [III] include the following, which are used alone or in combination of two or more, but are not limited thereto.

That is, ethylenediamine, 1,4-tetramethylenediamine, 1,6-hexamethylenediamine, isophoronediamine, m-xylylenediamine, p-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylether , 4,4'-methylenebis (2-chloroaniline) and the like. Of these, preferred are ethylenediamine, 1,4-tetramethylenediamine, 1,6
-Hexamethylenediamine, isophoronediamine.

The urea bond-containing polyurethane of the present invention is synthesized by adding the above-mentioned diisocyanate compound, diol compound and diamine compound to an aprotic solvent, adding a known catalyst having an activity corresponding to each reactivity, and heating. Preferably, a prepolymer is synthesized by reacting a diisocyanate compound with a diol compound, and then a diamine compound is added to synthesize the prepolymer.

In the above synthesis, the molar ratio of the sum of the diol compound and the diamine compound to the diisocyanate used is preferably selected from the range of 0.8: 1 to 1.2: 1, and when the isocyanate group remains at the polymer terminal, alcohols, amines Or water, the compound is finally synthesized so that no isocyanate group remains. The molar ratio between the diol compound and the diamine compound is preferably from 0.1: 0.9 to 0.9: 0.1, and more preferably from 0.2: 0.8 to 0.8: 0.2.

The molecular weight of the urea bond-containing polyurethane of the present invention is 5,000 or more, preferably 10,000 to 200,000 by weight average.

Further, the compounding weight ratio of the urea bond-containing polyurethane and the ethylenically unsaturated monomer or oligomer in the photosensitive composition of the present invention is 1: 0.1 to 1: 5, preferably
1: 0.2 to 1: 2.

Various plasticizers can be added to the photosensitive composition of the present invention in order to improve the developability and to control the physical properties of the resulting photocurable photosensitive layer.

The thickness of the photosensitive layer described above is not particularly limited, but is preferably selected from the range of 1 to 10 μm from the viewpoint of uniformity of the coating film and economy.

The silicone rubber layer preferably used in the present invention is a linear or partially crosslinked polydiorganosiloxane, and has the following repeating units.

Here, R represents an alkyl group, an aryl group, an alkenyl group or a monovalent group in which these are combined, and these are a halogen atom, an amino group, a hydroxy group, an alkoxy group, an aryloxy group, a (meth) acryloxy group, a thiol. It may have a functional group such as a group. In addition, as necessary, fine powder of inorganic substances such as silica, calcium carbonate, and titanium oxide, an adhesion aid with a silane coupling agent, a titanate coupling agent and an aluminum coupling agent, and a photopolymerization starter may be added to the silicone rubber. An agent may be added.

As a raw material of the high molecular polymer (silicone rubber) having the above-mentioned polysiloxane as a main skeleton, a polysiloxane having a molecular weight of thousands to hundreds of thousands and having a functional group at a terminal is used. It cures to give a silicone rubber layer. That is, specifically, a silane-based crosslinking agent represented by the following general formula is mixed into the above polysiloxane having a hydroxyl group at both ends or only at one end, and an organometallic compound, for example, an organotin compound, if necessary. Then, a catalyst such as an inorganic acid or an amine is added, and the polysiloxane and the silane-based crosslinking agent are heated or condensed and cured at room temperature.

R _n SiX _4-n wherein n is an integer of 1 to 3, R is a substituent similar to R shown above, and X is -OH, -OR ¹ , -OAc, Represents a substituent such as -Cl, -Br, I, etc., wherein R ¹ and R ² have the same meanings as R described above, and R ¹ and R ² may be the same or different; Ac represents an acetyl group.

In addition, the polysiloxane and the polyvalent hydrogen organopolysiloxane crosslinking agent and, if necessary, the above silane-based crosslinking agent are condensed and cured.

In addition, an addition type silicone rubber layer which is crosslinked by an addition reaction between a SiH group and a CH ₂ CHCH— group is useful. The addition type silicone rubber layer has an advantage that it is relatively insensitive to humidity during curing, and can be cross-linked at a high speed, so that certain physical properties can be easily obtained. The addition type silicone rubber layer used herein is obtained by the reaction of a polyvalent hydrogenene organopolysiloxane with a polysiloxane compound having two or more CH ₂ CHCH— bonds in one molecule. (1) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups (more preferably, vinyl groups) directly bonded to silicon atoms in one molecule. (2) Organohydro having at least two SiH bonds in one molecule. Diene polysiloxane 0.1 to 1000 parts by weight (3) A composition comprising 0.00001 to 10 parts by weight of an addition catalyst is cured and crosslinked. Ingredient (1)
The alkenyl group may be at the terminal of the molecular chain or at an intermediate position, and the organic group other than the alkenyl group is a substituted or unsubstituted alkyl group or aryl group. Ingredient (1)
May have a trace amount of hydroxyl groups. Ingredient (2)
Reacts with the component (1) to form a silicone rubber layer, but also plays a role in imparting adhesiveness to the photosensitive layer. The hydrogen group of the component (2) may be at the terminal of the molecular chain or at the middle, and the organic group other than hydrogen is selected from those similar to the component (1). It is preferable that 60% or more of the organic groups of the components (1) and (2) are methyl groups as a whole from the viewpoint of improving ink repellency. Component (1) and component (2)
The molecular structure of may be linear, cyclic, or branched,
It is preferable that at least one of the molecular weights exceeds 1,000 from the viewpoint of rubber physical properties, and it is more preferable that the molecular weight of the component (1) exceeds 1,000.

Examples of the component (1) include α, ω-divinylpolydimethylsiloxane, (methylvinylsiloxa) (dimethylsiloxane) copolymer having ethyl groups at both terminals, and the like.
Component (2) includes polydimethylsiloxane having both terminal hydrogen groups, α, ω-dimethylpolymethylhydrogenenesiloxane, (methylhydrogensiloxane) (dimethylsiloxane) copolymer having both terminal methyl groups, and cyclic polymethylhydrogen. Diene siloxane and the like are exemplified.

The addition catalyst of the component (3) is arbitrarily selected from known catalysts, and is particularly preferably a platinum compound, such as platinum alone, platinum chloride, chloroplatinic acid, and olefin-coordinated platinum. In order to control the curing rate of these compositions, organopolysiloxanes containing vinyl groups such as tetracyclo (methylvinyl) siloxane, alcohols containing carbon-carbon triple bonds, acetone, methyl ethyl ketone, methanol, ethanol, propylene glycol monomethyl It is also possible to add a crosslinking inhibitor such as ether.

These compositions have the characteristic that, when the three components are mixed, an addition reaction occurs and curing starts, but the curing rate increases rapidly as the reaction temperature increases. Therefore, for the purpose of extending the pot life until rubberization of the composition and shortening the curing time on the photosensitive layer, the curing conditions of the composition are temperature conditions within a range where the characteristics of the substrate and the photosensitive layer do not change. It is preferable to keep the temperature at a high temperature until it is completely cured from the viewpoint of the stability of the adhesive force with the photosensitive layer.

In addition to these compositions, a known adhesion-imparting agent such as alkenyl trialkoxysilane may be added, or a hydroxyl group-containing organopolysiloxane, a hydrolyzable functional group-containing silane (or (Siloxane) may be optionally added, and a known filler such as silica may be optionally added for the purpose of improving rubber strength.

The silicone rubber layer in the present invention serves as a printing ink repellent layer. If the thickness is small, there are problems such as a decrease in ink resilience and damage is easily caused. Therefore, the thickness is 0.5
μm to 5 μm are preferred.

In the waterless PS plate described herein, it is also optional to coat various silicone rubber layers on the silicone rubber layer, and to increase the adhesive strength between the photosensitive layer and the silicone rubber layer, or It is optional to provide an adhesive layer between the photosensitive layer and the silicone rubber layer for the purpose of preventing poisoning of the catalyst in the silicone rubber composition. To protect the surface of the silicone rubber layer, on the silicone rubber layer,
A transparent film such as polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, cellophane, or the like may be laminated, or a polymer coating may be applied.

The waterless PS plate according to the present invention is developed with a developer capable of dissolving a part of the photosensitive layer in the image area or swelling part or all of the photosensitive layer or a developer capable of swelling the silicone rubber layer after being exposed through the original image. Is done. In this case, there are cases where a part of the photosensitive layer in the image area and the silicone rubber layer on it are removed, and cases where only the silicone rubber layer in the image area is removed. Can be.

As a developer used in the present invention, PS without water
A known developer can be used as a plate developer. For example, aliphatic hydrocarbons [hexane, heptane, "Isoper E,
H, G "(trade name of aliphatic hydrocarbons manufactured by Esso Chemical Co., Ltd.)] or (gasoline, kerosene, etc.), aromatic hydrocarbons (toluene, xylene, etc.), or halogenated hydrocarbons (trichlene, etc.) To which the following polar solvent has been added.

・ Alcohols (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, tetraethylene glycol) Ketones (acetone, methyl ethyl ketone) Esters (ethyl acetate, methyl lactate) , Ethyl lactate,
(Butyl lactate, propylene glycol monomethyl ether acetate, carbitol acetate, dimethyl phthalate, diethyl phthalate) In development, for example, the silicone rubber layer in the image area is removed by rubbing the plate surface with a developing pad containing a developing solution as described above. Then, the photosensitive layer is exposed, and that portion becomes an ink receiving portion.

Also, the method described in JP-B-63-33140, namely,
Using a processing solution capable of dissolving at least a part of the photosensitive layer in the image area, a part or all of the photosensitive layer in the image area is eluted, and then water or water having no action to swell the silicone rubber layer is removed. A development method in which the silicone rubber layer in the image area is peeled off by rubbing the plate surface in the presence of a solvent as a main component is also applicable.

In order to confirm the image formability of the printing plate thus obtained,
The exposed image portion (photosensitive layer) is stained with a staining solution, and plate inspection is performed. By impregnating the dye solution into a soft pad and gently rubbing the image area, only the exposed image area of the photosensitive layer is dyed, whereby it can be confirmed that development has been sufficiently performed up to the highlight area. As the dyeing solution, one or more selected from water-soluble disperse dyes, acidic dyes and basic dyes are used alone or in a mixture of two or more solvents such as water, alcohols, ketones and ethers. What is dissolved or dispersed is used. It is also effective to add carboxylic acids, amines, surfactants, dyeing auxiliaries and the like in order to improve the dyeability.

〔The invention's effect〕

Since the photosensitive layer of the photosensitive lithographic printing plate precursor requiring no fountain solution according to the present invention contains a urea bond-containing polyurethane as a binder, the waterless lithographic plate obtained by exposure and development has high scratch resistance and high printing durability. In addition, there is no stickiness of the photosensitive layer, there is no peeling of the photosensitive layer in the unexposed area during the printing process, and the dyeability is excellent.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.

Reference 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) manufactured by Dainippon Ink and Chemicals, Inc.), 1,4 −
18 parts by weight of butanediol and 112.2 parts by weight of isophorone diisocyanate were dissolved in 1458.4 parts by weight of dimethylacetamide, and subjected to addition polymerization at 100 ° C. for 2 hours by a known method using di-n-butyltin dilaurate as a catalyst. Furthermore, 34.5 parts by weight of isophoronediamine was added as a chain extender,
The reaction was carried out at 100 ° C. for 1 hour to complete the reaction. The composition of the urea bond-containing polyurethane obtained in this manner has a raw material charge ratio (molar ratio) as shown in Example 1 in Table I below. In addition, in the same manner as described above,
And 3 polyurethanes containing urea bonds were synthesized. Comparative Example 1 according to the polyurethane synthesis method of the first step
And 2 binders were synthesized.

Examples 1 to 3 and Comparative Examples 1 to 2 A titanium white dispersion of the following formulation was applied on a smooth aluminum plate degreased by a normal method using a bar coater, and heat-treated at 200 ° C. for 20 minutes to dry weight. 2.0g /
It provided a primer layer of m ^2.

On each of the five aluminum plates coated with the primer layer, five types of photosensitive liquids were prepared according to the following photopolymerizable photosensitive composition formulation using binders of five types of raw material charging ratios shown in Table I. The photosensitive layer was provided so as to have a dry weight of 4.0 g / m ² .

The surfaces of the five types of photosensitive layers obtained as described above were slightly pressed with a finger, and whether or not fingerprint marks were generated was examined. The results shown in Table I were obtained.

In addition, the following silicone rubber composition was applied on the photosensitive layers of five plates each at a dry weight of 2.0 g / m ² and dried to obtain a cured silicone rubber layer.

A 9 μm thick single-side matted OPP (biaxially oriented polypropylene) film having a thickness of 9 μm was laminated on the surface of the silicone rubber of the waterless PS plate obtained as described above, and the waterless PS plate was prepared in Examples 1 to 3 and Comparative Example 1. ~ 2.

Each of the five water-free PS plates thus obtained was overlaid with a positive film, adhered in vacuum, exposed to an image using a normal exposure device, and then the laminate film was peeled off.
Immerse in polypropylene glycol (molecular weight 200) at 40 ° C for 1 minute. After immersion, the treatment liquid adhering to the plate surface and the back surface was removed with a rubber squeegee, and the silicone rubber layer in the image area was peeled off by rubbing lightly with a pad while sprinkling tap water. Subsequently, staining was carried out with a staining solution having the following formulation, and the staining density of the image area (solid) was examined with a reflection densitometer (Macbeth RD 920). The results shown in Table I were obtained.

After printing 10,000 sheets with Toyo Ink's Aquares VG black ink on a Komori Lithrone 26 printing machine with the dampening water supply device removed using the plate obtained in this way, the photosensitive layer in the image area was worn. When it was checked whether or not the results were obtained, the results shown in Table I were obtained.

Example 4 An aluminum plate provided with a primer layer was prepared in the same manner as in Examples 1 to 3. A binder having the following raw material charge ratio was synthesized on the aluminum plate in the same manner as in Reference Example 1,
Using this binder, a photosensitive solution having the following photopolymerizable photosensitive composition was prepared, and a photosensitive layer having a dry weight of 4.0 g / m ² was provided on the aluminum plate.

* EG 6000: polyethylene glycol (molecular weight 7500) (manufactured by Wako Pure Chemical Industries, Ltd.) Even if the surface of the photosensitive layer obtained in this way is lightly pressed with a finger, it does not stick and fingerprint marks are generated. Did not.

Next, the same silicone rubber composition as in Examples 1 to 3 was applied on the photosensitive layer to a dry weight of 2.0 g / m ² ,
After drying, a cured silicone rubber layer was obtained.

A 9 μm thick single-sided matted OPP (biaxially oriented polypropylene) film was laminated on the surface of the silicone rubber layer of the waterless PS plate obtained as described above to obtain a waterless PS plate.

The PS plate without water thus obtained was made in the same manner as in Examples 1 to 3.

When the dyeing density of the obtained printing plate was examined, the density was 1.
It was 39.

After printing 10,000 sheets using the plate thus obtained under the same conditions as in Examples 1 to 3, the abrasion degree of the photosensitive layer in the image area was examined, and no abrasion was observed.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shizuka Hirano 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Inside Fuji Photo Film Co., Ltd. (56) References JP-A-63-74064 (JP, A) JP-A-63- 74065 (JP, A) JP-A-63-280250 (JP, A) JP-A-3-200965 (JP, A)

Claims (2)

(57) [Claims] 1. A lithographic printing plate precursor that does not require a fountain solution and has a photopolymerizable photosensitive layer and a silicone rubber layer in this order on a support, wherein the photosensitive layer contains a urea bond-containing polyurethane as a binder. A lithographic printing plate precursor requiring no dampening solution, comprising a polymerizable photosensitive composition. 2. The polyurethane according to claim 1, further comprising an ester bond and / or
Or a lithographic printing plate precursor requiring no dampening solution according to claim 1 or containing an ether bond.