JP3036390B2 - Photosensitive lithographic printing plate precursor and method for producing lithographic printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive lithographic printing plate precursor, which has a high ink repellency without desensitizing treatment and a novel photosensitive material capable of using pure water as a dampening solution. It relates to a lithographic printing plate.

[0002]

2. Description of the Related Art In lithographic printing, an image area and a non-image area are basically present on substantially the same plane, and the image area is made ink-receptive and the non-image area is made ink-repellent. Utilizing the difference in adhesiveness, after inking ink only on the image area,
This refers to a method of printing by transferring ink onto a printing medium such as paper. A PS plate is usually used for such lithographic printing.

[0003] The PS plate mentioned here means the following.

[0004] That is, Teruhiko Yonezawa, "PS Version Overview"
As described in pp. 18-81 of the Printing Society of Japan (1993), a lipophilic photosensitive resin layer is applied on an aluminum substrate that has been subjected to hydrophilic treatment, and the image portion is formed by photolithography. The photosensitive layer remains, while the non-image area exposes the surface of the aluminum substrate described above, forms a dampening solution layer on the surface, repels ink, and forms a PS plate with water for forming an image and a dampening solution layer. Instead, a waterless PS plate using a silicone rubber layer as an ink repellent layer, a so-called waterless planographic plate.

[0005] The term "waterless lithographic printing plate" used herein means that the non-image area is made of a substance having ink repellency to oil-based ink used in normal lithographic printing, such as silicone rubber or a fluorine-containing compound. This means a printing plate that can be used to form an image between an ink-impartable image portion and print without using the same.

[0006] The former PS plate with water is a printing plate excellent in practical use. Usually, aluminum is used for the support, and the aluminum surface has water retention and a lipophilic photosensitive resin layer is formed from the surface during printing. It was necessary to have excellent adhesion to the photosensitive layer so as not to peel off. Therefore, the aluminum surface is usually grained, and if necessary, a treatment such as anodizing is performed on the grained surface to improve water retention and reinforce adhesion to the photosensitive resin layer. I have been. Further, in order to obtain the storage stability of the photosensitive resin layer, the aluminum surface is generally subjected to a chemical treatment such as zirconium fluoride or sodium silicate.

As described above, the PS plate with water has a complicated manufacturing process and its simplification has been desired. However, the PS plate has been widely used because of its excellent printing characteristics (printing durability, image reproducibility, etc.). I have.

In order to solve the above-mentioned problem, there is a proposal of a new planographic material having printing characteristics equal to or better than that of an aluminum substrate and having a low material cost and different from an aluminum substrate by a simple manufacturing process. For example, Japanese Patent Publication No. Sho 56-2938 proposes a method of forming a photosensitive layer on a support using an ink repellent layer made of a hydrophilic polymer material instead of an aluminum substrate. ing. However, in this method, since a urea resin is simply applied as a hydrophilic layer on a water-resistant layer of an aldehyde condensate of polyvinyl chloride, polyurethane, or polyvinyl alcohol, the layer has insufficient ink repellency. In addition, the adhesiveness to the photosensitive resin layer was poor, and the printing durability was insufficient. In JP-A-57-179852, a hydrophilic radical polymerizable compound is coated on a support, the surface of the support is hydrophilized by irradiation with actinic rays, and a photosensitive resin layer is coated. A method has been proposed. However, the hydrophilic surface layer formed by this method was also rigid, had insufficient ink repellency, and had poor printing durability.

In the development of the PS plate with water, since the photosensitive layer is dissolved to expose the aluminum substrate surface, it is essential that the photosensitive layer components be dissolved in the developing solution. In this case, the composition fluctuates greatly in a short period of time, causing fatigue, and a large amount of developing waste liquid is generated.

Therefore, the developer has to be frequently maintained and replaced. In addition, a great deal of labor and cost are required for treating the generated developing waste liquid.

Further, as a simple form of the PS plate with water,
An image receiving layer such as toner is formed on a support such as paper
A direct-drawing lithographic printing plate precursor that forms an image using a PC, desensitizes non-image areas with an etchant or the like, and converts the image receiving layer into an ink repellent layer for use is widely used. . Specifically, an image receiving layer comprising a water-soluble binder polymer, an inorganic pigment, a water-proofing agent and the like is generally provided on a water-resistant support, and is disclosed in US Pat. No. 2,532,865, Japanese Patent Publication No. 40-23581, and JP-A-48-9802, JP-A-57-205196, JP-A-60-2
309, JP-A-57-1791, JP-A-5-1791
JP-A-7-15998, JP-A-57-96900, JP-A-57-205196, JP-A-63-1
66590, JP-A-63-166593,
JP-A-63-317388, JP-A-1-1144
No. 88, JP-A-4-366868, and the like. These direct-drawing lithographic printing plate precursors include PVA, starch, hydroxyethylcellulose, casein, gelatin, polyvinylpyrrolidone, vinyl acetate-crotonic acid copolymer, styrene-maleic acid copolymer as an image receiving layer to be converted into an ink repellent layer. Water-dispersible polymers such as water-soluble binder polymers and acrylic resin emulsions that exhibit hydrophilicity before the desensitization treatment such as coalescence, inorganic pigments such as silica and calcium carbonate, and melamine-formaldehyde resin condensates There are proposals made of such a waterproofing agent. Also, JP-A-63-2
Japanese Patent No. 56493 proposes a direct drawing type lithographic printing plate precursor using as a main component a hydrophobic polymer which is hydrolyzed by a desensitizing treatment to generate a hydrophilic group.

In order to convert the image receiving layer into an ink repellent layer, the direct drawing type lithographic printing plate requires desensitization treatment, and without such treatment, shows little ink repellency. It was.

That is, in order to obtain a practical level of ink repellency, it is necessary to desensitize the ink and to use a large amount of a hydrophilic binder polymer. However, the water resistance tends to be poor, and the printing durability deteriorates. . Further, when the hydrophilicity is increased, there is a problem that the adhesiveness to an image such as a toner tends to decrease. On the other hand, if the water resistance is increased by increasing the amount of a water-proofing agent or by adding a hydrophobic polymer in order to improve printing durability, the hydrophilicity is reduced, and the ink repellency is greatly reduced. There was a problem.

A so-called exposure-only, one-step version of the technology developed by Union Carbide, which does not require any development, lacquer embossing, or desensitization treatment utilizing a hydrophilic / hydrophobic conversion reaction is disclosed in No. 131, Japanese Patent Publication No. Sho 4
No. 2-5365, Japanese Patent Publication No. 42-14328,
JP-B-42-20127, US Pat. No. 3,321,377
JP, USP3231381, USP3231
No. 382, for example. The plate is formed by coating an association of polyethylene oxide and a phenolic resin together with a photosensitizer. However, the non-image portion is rigid and inferior in flexibility, and the ink repellency is insufficient. The difference in ink repulsion / ink deposition between the line and
It was not practical.

Further, the PS plate with water needs to constantly control the amount of dampening solution at the time of printing, and considerable skill and experience have been required to control an appropriate amount of dampening solution. IPA added as an essential component to the fountain solution
In recent years, the use of (isopropanol) has been strictly regulated from the standpoint of the occupational health environment and wastewater treatment, and countermeasures are urgently needed.

On the other hand, in the case of a waterless PS plate in which a silicone rubber layer is used as an ink repellent layer instead of the fountain solution, JP-B-54-26923, JP-B-57-3060, and JP-B-56-12682. No., JP-B-56-23
No. 150, JP-B-56-30856, JP-B-60-60051, JP-B-61-54220, JP-B-61-54222, and JP-B-61-54.
No. 223, Japanese Patent Publication No. 61-616, Japanese Patent Publication No. 63
JP-A-23544, JP-B-2-25498, JP-B3-56622, JP-B4-28098, JP-B5-1934, and JP-A-2-63050.
As described in Japanese Patent Application Laid-Open No. 2-63051 and the like, printing can be performed without using a dampening solution, so that there is no need to control the dampening solution necessary for the former PS plate with water. Since the work becomes extremely simple, it is a highly practical plate material that has been rapidly spreading in recent years, but lack of durability has been pointed out because a silicone rubber layer having low mechanical strength is used as the ink repellent layer. There is a strong demand for ink repellent materials having excellent durability. Further, at the time of development, it is necessary to mechanically peel and remove the silicone rubber layer by brush rubbing, so that a large amount of development waste liquid containing the peeled and removed silicone rubber residue is generated. Therefore, the service life of the brush is short and it is necessary to frequently replace the brush, and maintenance measures such as collecting and discarding the silicone rubber residue have been required.

[0017]

SUMMARY OF THE INVENTION The present inventors have expanded the control range of fountain solution for lithographic printing of these conventional PS plates with water, and have eliminated IPA from fountain solution, which has been considered impossible. And a waterless lithographic printing plate having a silicone rubber layer as an ink repellent layer without having a complicated plate making process such as forming an image by a PPC method and performing desensitization processing as in a direct drawing type lithographic printing original plate. In addition to eliminating the drawback of lack of durability, it does not require the development maintenance required for conventional PS plates, and has been intensively studying the development of ideal lithographic materials that are simple in the manufacturing process. It has been found that this can be realized by using a hydrophilic swelling layer having a phase separation structure composed of a group as an ink repellent layer and using a lipophilic ethylenically unsaturated compound as a photosensitive component.

[0018]

That is, the present invention has the following configuration.

(1) At least the ink repulsion on the substrate
A photosensitive lithographic printing plate precursor comprising a hydrophilic and photosensitive hydrophilic swelling layer, wherein the hydrophilic swelling layer contains a lipophilic ethylenically unsaturated compound and is inked by irradiation with actinic rays.
A photosensitive lithographic printing plate precursor characterized by a change in flesh .

(2) The hydrophilic swelling layer has a phase separation structure composed of at least two phases of a phase mainly composed of a hydrophilic polymer and a phase mainly composed of a hydrophobic polymer. (1) The photosensitive lithographic printing plate precursor described in the above.

(3) The photosensitive lithographic printing plate precursor as described in (1) above, further comprising a protective layer on the hydrophilic swelling layer.

(4) The plate surface of the photosensitive lithographic printing plate precursor as described in (1) above is irradiated with actinic rays, and the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer corresponding to the image area is provided. And then removing the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer in the portion corresponding to the non-image area.

(5) The removal of the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer in the portion corresponding to the non-image area,
The method for producing a lithographic printing plate as described in (4) above, wherein the entire surface of the plate is washed with water.

The hydrophilic swelling layer of the photosensitive lithographic printing plate precursor according to the invention will be described.

The hydrophilic swelling layer is photosensitive and contains a lipophilic ethylenically unsaturated compound as a photosensitive compound.

The lipophilic ethylenically unsaturated compound of the present invention will be described.

The lipophilic ethylenically unsaturated compound of the present invention means a photopolymerizable monomer or oligomer having a solubility in water at 20 ° C. of 8% by weight or less.

Specific examples of the lipophilic ethylenically unsaturated compound preferably used in the present invention include compounds represented by the following general formula (I).

CH ₂ ＣC (R ¹ ) —CO—O— (CH ₂ ) _n —R ² (I) (where R ¹ represents hydrogen or a methyl group; R ² represents hydrogen, carbon number 1 to 1) 20 substituted or unsubstituted alkyl groups, nitro groups, azido groups, alkenyl groups having 2 to 20 carbon atoms, substituted or unsubstituted aryl groups having 4 to 20 carbon atoms,
Represents a substituted or unsubstituted aralkyl group, acryloxy group or methacryloyloxy group. n is an integer of 1 to 30. Specific examples include the following compounds.

[0030]

Embedded image n means the average value of the compound represented by the above general formula. That is, the compound represented by the above general formula comprises a mixture having a distribution of n.

These compounds have n
Is preferably an integer of 4 to 30, and more preferably 8 to 13. When n is 3 or less, the lipophilicity tends to be insufficient, and the ink deposition property tends to be insufficient. If n is 31 or more, the equivalent weight of the unsaturated group per weight is insufficient, and the photosensitivity is reduced. For example, n is 4, 5, 6, 7, 8, 9, 10, 1
Compounds such as 3,22 can be used.

Specific examples of the lipophilic ethylenically unsaturated compound preferably used in the present invention other than the general formula (I) include 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, neopentyl glycol diacrylate, neopentyl Examples include glycol dimethacrylate, isooctyl acrylate, and isooctyl methacrylate.

These lipophilic ethylenically unsaturated compounds can be used alone or in combination of two or more.

The lipophilic ethylenically unsaturated compound preferably used in the present invention is added to the composition when the hydrophilic swelling layer is formed, and the lipophilic ethylenically unsaturated compound is present in the hydrophilic swelling layer. After formation, the compound is added onto the layer, if necessary, by diluting with a suitable solvent that easily penetrates the hydrophilic swelling layer, applying the diluted solution, and impregnating the layer.

When a relatively high molecular weight oligomer or the like is used, the former method of simultaneous addition during the formation of the hydrophilic swelling layer is advantageously performed, and when a relatively low molecular weight monomer or oligomer is used, the latter method is used. Is advantageous.

The hydrophilic swelling layer used in the photosensitive lithographic printing plate precursor according to the present invention has a phase separation composed of at least two phases of a phase mainly composed of a hydrophilic polymer and a phase mainly composed of a hydrophobic polymer. It preferably has a structure.

The hydrophilic polymer used in the hydrophilic swelling layer of the present invention will be described.

The hydrophilic polymer is a known water-soluble polymer (which means completely soluble in water) or a pseudo-water-soluble polymer (amphiphilic) which is substantially insoluble in water and shows water swellability. Macro means a substance that dissolves in water but micro contains a non-dissolved portion), and a water-swellable polymer (means one that swells in water but does not dissolve).
That is, it refers to a polymer that adsorbs or absorbs water under normal use conditions, and a polymer that dissolves in or swells in water.

Examples of the hydrophilic polymer that effectively exerts the effects of the present invention include carboxylate copolymers.

The carboxylate copolymer preferably used in the present invention includes, from the viewpoint of water absorption and durability,
Α, β-unsaturated compounds having one or two carboxyl groups or carboxyl group-derived groups such as carboxyl groups, carboxylate salts, carboxylic acid amides, carboxylic acid imides, carboxylic anhydrides, etc. A saponification reaction product of a carboxylic acid copolymer contained as a component is exemplified.

Specific examples of the α, β-unsaturated compound include:
Acrylic acid, methacrylic acid, acrylamide, methacrylamide, maleic anhydride, maleic acid, maleic amide, maleic imide, itaconic acid, crotonic acid, fumaric acid, mesaconic acid, and the like, which are necessary for the present invention. It is possible to combine with another monomer component copolymerizable within a range showing hydrophilicity.

Examples of other copolymerizable monomer components include ethylene, propylene, isobutylene, 1-butylene, diisobutylene, methyl vinyl ether, styrene, vinyl acetate, acrylates, methacrylates, and acrylonitrile. Olefin, vinyl compound, vinylidene compound and the like can be mentioned.

When combined with another monomer, the α, β-unsaturated compound containing a carboxyl group or a group which can be converted into the carboxyl group is usually present in an amount of at least 10 mol% of all monomer components.
More preferably, it is at least 40 mol%.

The polymer containing, as a monomer, an α, β-unsaturated compound containing a carboxyl group or a group which can be converted to the carboxyl group is usually prepared by radical polymerization. The degree of polymerization is not particularly limited.

Among the above-prepared polymers, a polymer or a copolymer of acrylic acid and methacrylic acid, an α-olefin, and a copolymer of a vinyl compound and maleic anhydride are particularly preferable.

These polymers or copolymers are prepared using compounds such as hydroxides, oxides or carbonates of alkali metals or alkaline earth metals such as sodium, potassium, magnesium and barium, ammonia and amines. Hydrophilicity is preferably imparted by a saponification reaction. In these reactions, the polymer or the copolymer is dissolved or dispersed in various organic solvents or water, and the above-mentioned alkali metal compound, alkaline earth metal compound, ammonia, amine and the like are added thereto with stirring. It is implemented by.

Among such carboxylate-based copolymers, vinyl ester / (meth) acrylate copolymers are particularly preferred because the hydrophilic swelling layer exhibits an appropriate water swelling property, the printing durability and the ink durability. It is preferable in that both of the resilience are satisfied.

The vinyl ester / (meth) acrylate copolymer preferably used in the present invention can be produced by a known method. For example, polymer chemistry, 7
Vol. 142, p. 1950. That is, it is appropriately selected depending on the polymerization method, for example, polymerization initiation of peroxides such as di-t-butyl peroxide and benzoyl peroxide, persulfates such as ammonium persulfate, and azo compounds such as azobisisobutyronitrile. It is synthesized by radical polymerization using an agent. As the polymerization method,
Solution polymerization, emulsion polymerization, suspension polymerization and the like are required. When the amount of the (meth) acrylic acid ester component in the copolymer is small, the water absorption is small. When the amount is too large, the water absorption state is high and the film strength tends to be extremely lowered.

Therefore, the ratio of the (meth) acrylate component in the copolymer as the starting material is generally preferably in the range of 20 to 80 mol%, and both the water absorption and the mechanical strength at the time of containing water are compatible. 30 ~
It is preferably 70 mol%.

The vinyl ester used in the present invention includes vinyl acetate, vinyl propionate, vinyl stearate and the like. As the (meth) acrylic acid ester, an alkyl ester of (meth) acrylic acid,
Specific examples include methyl ester, ethyl ester, n-propyl ester, isopropyl ester, n-butyl ester and t-butyl ester.

The copolymer described above preferably undergoes a saponification reaction in the presence of an alkali catalyst. As the solvent used for the saponification reaction, alcohol and an aqueous alcohol solution are preferable. As the catalyst used for the saponification reaction, a known alkali catalyst is used, and an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is particularly preferable. The saponification reaction is completed at 20 to 80 ° C for 1 to 10 hours. The salt of the saponification reaction product of the present invention can be arbitrarily changed by a known method. Commonly used salt-forming substances include sodium hydroxide, potassium hydroxide, ammonium hydroxide, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, and monoethanolamine. , Diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N, N-dimethylethanolamine, N, N-
Examples include dimethylisopropanolamine, cyclohexylamine, benzylamine, aniline, pyridine and the like.

Polyvalent metal salts of alkaline earth metal salts such as magnesium and calcium can be added in the form of a mixed salt with the above-mentioned salts.

A known hydrophilic polymer can be added to the hydrophilic swelling layer of the present invention as long as the effects of the present invention are not impaired. The following examples can be given as known hydrophilic polymers.

(A) Natural polymers: starch-acrylonitrile-based graft polymer hydrolyzate, starch-acrylic acid-based graft polymer, starch-styrene sulfonic acid-based graft polymer, starch-
Vinyl sulfonic acid type graft polymer, starch-acrylamide type graft polymer, carboxylated methyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, xanthate cellulose, cellulose-acrylonitrile type graft polymer, cellulose-styrene sulfonic acid type graft polymer , A carboxymethylcellulose-based crosslinked product,
Hyaluronic acid, agarose, collagen, milk casein, acid casein, rennet casein, ammonia casein, potashized casein, borax casein, glue, gelatin, gluten, soy protein, alginate, ammonium alginate, potassium alginate, sodium alginate gum arabic , Tragacanth gum, karaya gum, guar gum, locust bean gum, Irish moss,
Soy lecithin, pectic acid, starch, carboxylated starch, agar, dextrin, mannan, etc.

(B) Synthetic polymers Polyvinyl alcohol, polyethylene oxide, poly (ethylene oxide-co-propylene oxide), aqueous urethane resin, water-soluble polyester, hydroxyethyl (meth) acrylate-based polymer ) □□□□ means □□□□ or meta □□□□
Is abbreviated. ), Poly (vinyl methyl ether)
-co-maleic anhydride), maleic anhydride-based copolymer, vinylpyrrolidone-based copolymer, polyethylene glycol di (meth) acrylate-based crosslinked polymer, polypropylene glycol di (meth) acrylate-based crosslinked polymer.

The above-mentioned hydrophilic polymer may contain one or two monomers or copolymer components having different substituents for the purpose of imparting flexibility or controlling hydrophilicity, as long as the effects of the present invention are not impaired. It is possible to mix and use more than one kind as appropriate.

Next, the hydrophobic polymer used in the hydrophilic swelling layer of the present invention will be described.

As the hydrophobic polymer used in the present invention, those mainly composed of an aqueous emulsion are preferably used.

The aqueous emulsion referred to in the present invention means an aqueous solution of a hydrophobic polymer in which particles comprising fine polymer particles and, if necessary, a protective layer surrounding the particles are dispersed in water.

That is, it means a self-emulsifying or forced emulsifying aqueous solution basically composed of emulsion particles composed of polymer particles as a dispersoid, a protective layer formed as required, and a dilute aqueous solution as a dispersion medium. Specific examples of the aqueous emulsion used in the present invention include a vinyl polymer latex, a conjugated diene polymer latex, and an aqueous or water-dispersed polyurethane resin.

Examples of the vinyl polymer type latex include acrylic type, vinyl acetate type and vinylidene chloride type. Examples of the conjugated diene polymer-based latex include styrene / butadiene-based (hereinafter abbreviated as SB-based), acrylonitrile / butadiene-based (hereinafter abbreviated as NB-based), methyl methacrylate / butadiene-based (hereinafter abbreviated as MB-based),
Chloroprenes and the like can be mentioned.

Examples of the acrylic latex include copolymers containing acrylate and methacrylate as essential components. Specific examples include those obtained by copolymerizing at least one or more of methyl methacrylate, ethyl acrylate, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and styrene.

Examples of the vinyl acetate latex include vinyl acetate alone or a copolymer with acrylic ester, higher vinyl acetate, ethylene, or the like.

Examples of the vinylidene chloride-based latex include copolymers of vinylidene chloride with methyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, acrylonitrile, vinyl chloride, and the like.

As the SB latex, styrene and butadiene are essential components, and methyl methacrylate,
Examples include higher acrylic acid esters, acrylonitrile, acrylamide, hydroxyethyl acrylate, and copolymers with unsaturated carboxylic acids (such as itaconic acid, maleic acid, acrylic acid, and methacrylic acid).

As the aqueous or water-dispersible polyurethane resin, a hydrophobic polyurethane resin composed of polyester polyol, polyether polyol, poly (ester / ether) polyol and polyisocyanate is forcibly emulsified using a surfactant. Emulsifying type, self-emulsifying type in which a hydrophilic group or a hydrophilic segment is imparted to the resin itself and emulsified in a self-dispersing manner, and non-reactive ones in both, and a reactive group such as an isocyanate group in a blocking agent And those having reactivity blocked.

Among these aqueous emulsions, the hydrophobic polymer particularly preferably used in the present invention is SB.
Latex containing conjugated diene-based compounds such as styrene, NB-based, MB-based, and chloroprene-based compounds.

The conjugated diene rubber mentioned here includes:
1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene (chloroprene)
Means a compound having an unsubstituted or substituted 1,3-butadiene skeleton having a carbon-carbon double bond at the 1,3-position, such as a homo- or block copolymer rubber (polymer) having these as essential components. .

Examples of the block copolymer rubber include 1,3-diene such as 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene), styrene and α-methyl which give a glassy polymer at ordinary temperature. A block copolymer with a monovinyl-substituted aromatic compound such as styrene and vinyltoluene is exemplified.

As such a copolymer rubber, various known types can be exemplified, and an ABA type block copolymer rubber (where A is a monovinyl-substituted aromatic compound, preferably a glass transition rubber) A polymer segment having a point of 70 ° C. or higher and a degree of polymerization of 10 to 2500, and B means 1,3-diene, preferably an amorphous polymer segment having a number average molecular weight of 500 to 25,000. And the like). The same applies to the hydrogenated product of the block copolymer rubber.

Specific examples of the homo- and copolymer rubbers used in the present invention include polybutadiene, polyisoprene (including natural rubber), polychloroprene, styrene-butadiene copolymer, carboxy-modified styrene-butadiene copolymer, acrylic Acid ester-butadiene copolymer (for example, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer), methacrylate-butadiene copolymer, isobutylene-isoprene copolymer, acrylonitrile-butadiene copolymer Polymer, carboxy-modified acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, vinylpyridine-butadiene copolymer, vinylpyridine-styrene-butadiene copolymer,
Styrene-chloroprene copolymer, styrene-isoprene copolymer and the like can be mentioned.

The conjugated diene polymer latex preferably used in the present invention is prepared by a known method. For example, 0.1 to 20% by weight of an emulsion polymerization dispersant based on a vinyl monomer composition containing a conjugated diene compound as an essential component. (E.g., a surfactant) and an aqueous medium containing 2 to 50% by weight of water and degassed with nitrogen, emulsified, and, if necessary, additives (molecular weight modifier, antioxidant) used in ordinary emulsion polymerization. ), An initiator for emulsion polymerization (eg, hydrogen peroxide, potassium persulfate, etc.) is added, and emulsion polymerization is carried out according to a conventional method.

In the raw material vinyl monomer composition, the vinyl monomer used other than the conjugated diene compound is not particularly limited, but mainly the following group I: hydrophobic monomer, II
Group: hydrophilic monomers, Group III: can be classified into three groups of crosslinkable monomers.

Group I: The hydrophobic monomer is a hydrophobic vinyl monomer having one vinyl group (the hydrophobicity means a solubility in water at 20 ° C. of 8% by weight or less) and acrylic. Acid esters, methacrylic esters, vinyl esters, styrenes, olefins and the like can be mentioned.

Specific examples of acrylic esters include:
Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, 2-phenoxyethyl acrylate, 2
-Chloroethyl acrylate, benzyl acrylate,
Examples include cyclohexyl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, 2-methoxyethyl acrylate, and 2-ethoxyethyl acrylate.

Specific examples of the methacrylates include methyl methacrylate, ethyl methacrylate, n
-Propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, acetoacetoxyethyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, furfuryl methacrylate, tetrahydrofur Examples thereof include furyl methacrylate, phenyl methacrylate, trimethylolpropane monomethacrylate, 2-methoxyethyl methacrylate, and 2-ethoxyethyl methacrylate.

Specific examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxy acetate, vinyl acetoacetate, vinyl benzoate, vinyl salicylate, and chlorobenzoate. Vinyl acid and the like.

Specific examples of styrenes include styrene,
α-methylstyrene, chloromethylstyrene, trifluoromethylstyrene, acetoxymethylstyrene, methoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, bromostyrene and the like.

Specific examples of the olefins include propylene, vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene bromide, vinylidene fluoride and the like.

Other examples include acrylonitrile and maleic anhydride.

Group II: The hydrophilic monomer is a hydrophilic vinyl monomer having one vinyl group. (Hydrophilic herein means a monomer that has a high solubility in water and cannot be used alone in aqueous emulsion polymerization. A) a monomer having a functional group such as an amino group, a carboxyl group, a sulfonic acid group, an amide group, or a hydroxyl group.

Specific examples of the monomer having an amino group include dimethylaminomethyl acrylate, dimethylaminomethyl methacrylate, diethylaminomethyl acrylate, diethylaminomethyl methacrylate,
t-butylaminoethyl acrylate, tert-butylaminoethyl methacrylate and the like.

Specific examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, fumaric acid, methylenemalonic acid, monoalkyl itaconate (for example, monomethyl itaconate,
Monoethyl itaconate, monobutyl itaconate, etc.),
Monoalkyl maleate (eg, monomethyl maleate, monoethyl maleate, monobutyl maleate, etc.), citraconic acid, sodium acrylate, ammonium acrylate, ammonium methacrylate and the like can be mentioned.

Specific examples of the monomer having a sulfone group include styrenesulfonic acid, vinylbenzylsulfonic acid, vinylsulfonic acid, vinylsulfonic acid, acryloyloxyalkylsulfonic acid (for example, acryloyloxymethylsulfonic acid, acryloyloxypropylsulfonic acid, Acryloyloxybutylsulfonic acid, etc.), methacryloyloxyalkylsulfonic acid (eg, methacryloyloxymethylsulfonic acid, methacryloyloxymethylsulfonic acid, methacryloyloxypropylsulfonic acid, methacryloyloxybutylsulfonic acid, etc.), acrylamide alkylsulfonic acid (eg, 2-acrylamide) -2-methylethanesulfonic acid, 2-acrylamide-2-methylpropanesulfur Phosphate, 2-acrylamido-2
Methylbutanesulfonic acid, etc.), methacrylamide alkylsulfonic acid (eg, 2-methacrylamide-2)
-Methylethanesulfonic acid, 2-methacrylamide-
2-methylpropanesulfonic acid, 2-methacrylamide-2-methylbutanesulfonic acid, etc.).

Specific examples of the monomer having an amide group include acrylamide, methylacrylamide, propylacrylamide and the like.

Specific examples of the monomer having a hydroxyl group include:
Examples include allyl alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and aryl ethers of polyhydric alcohols.

Other examples include N-acryloylpiperidine, vinylpyridine, vinylpyropide and the like.

Group III: Examples of the crosslinkable monomer include monomers having a reactive crosslinkable group (glycidyl group, hydroxymethylamide group, alkoxymethylamide group, acyloxymethylamide group, isocyanate group, etc.) and two or more vinyls. Polyfunctional monomers having a group are exemplified.

Specific examples of the monomer having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, glycidyl p-vinylbenzoate, glycidyl crotonate, diglycidyl itaconate, diglycidyl maleate, diglycidyl methylene malonate, glycidyl vinyl ether, Allyl glycidyl ether, glycidyl-α-chloroacrylate and the like can be mentioned.

Specific examples of the monomer having a hydroxymethylamide group include hydroxymethylacrylamide,
And hydroxymethyl methacrylamide.

Specific examples of the monomer having an alkoxymethylamide group include methoxymethylacrylamide, methoxymethylmethacrylamide, ethoxymethylacrylamide, ethoxymethylmethacrylamide, butoxymethylacrylamide, butoxymethylmethacrylamide, hexyloxymethylmethacrylamide and the like. No.

Specific examples of the monomer having an acyloxymethylamide group include acetoxymethylacrylamide,
Examples include acetoxymethyl methacrylamide and propionyloxymethyl acrylamide.

Specific examples of the monomer having an isocyanate group include vinyl isocyanate and allyl isocyanate.

Specific examples of the polyfunctional monomer include divinylbenzene, polyethylene glycol diacrylate (ethylene number n = 1 to 23), polyethylene glycol dimethacrylate (ethylene number n = 1 to 23), trimethylolpropane triacrylate, and trimethylolpropane triacrylate. Methylol propane trimethacrylate, pentaerythritol triacrylate and the like can be mentioned.

Suitable combinations of monomers for preparing the latex preferably used in the present invention include, in addition to the conjugated diene compound which is an essential component, (1) a copolymer of at least one or more Group I monomers (2) Copolymer with at least one or more Group I monomers and at least one or more Group II monomers (3) At least one or more Group I monomers and at least one or more Group II monomers and at least one or more II
Copolymers with Group I monomers (4) Combinations of at least one or more copolymers of Group I monomers and Group III monomers, and the like, but the present invention is not limited to these combinations.

Specific examples of the conjugated diene polymer latex preferably used in the present invention include JSR0561.
(SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), J
SR0589 (SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0602 (SB copolymer latex:
JSR0700 (butadiene polymer latex: manufactured by Japan Synthetic Rubber Co., Ltd.), JSR21
08 (SB copolymer latex: Nippon Synthetic Rubber Co., Ltd.)
JSR0650 (vinyl pyridine-SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0652
(Vinyl pyridine-SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0545 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR05
48 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0596 (carboxy-modified SB
Copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0
597 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0598 (carboxy-modified S
B copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR
0619 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0624 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JS
R0640 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0693 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), J
SR0696 (carboxy-modified SB copolymer latex:
Nippon Synthetic Rubber Co., Ltd.), JSR0854 (carboxy-modified SB copolymer latex: Nippon Synthetic Rubber Co., Ltd.),
JSR0863 (carboxy-modified SB copolymer latex: manufactured by Nippon Synthetic Rubber Co., Ltd.), JSR0898 (carboxy-modified SB copolymer latex: Japan Synthetic Rubber Co., Ltd.)
), Rack Star 4940B (carboxy-modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Rack Star 68-073S (carboxy-modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), rack Star DN-704 (carboxy-modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Luck Star DN-702 (carboxy-modified NB copolymer latex:
Dainippon Ink and Chemicals Co., Ltd.), Rack Star 68-
074 (carboxy-modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Luck Star DN-703
(Carboxy-modified NB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Luck Star DM-801 (carboxy-modified MB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.), Luck Star DM-401 (carboxy Modified MB copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc., Luckstar 4950C (carboxy-modified MB copolymer latex: Dainippon Ink and Chemicals, Inc.)
Co., Ltd.), Luck Star DM-806 (carboxy-modified MB)
Copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.).

These conjugated diene polymer latexes can be used alone or in appropriate combination of two or more.

The hydrophilic swelling layer of the present invention is formed on the substrate by mixing the above-mentioned hydrophilic polymer and hydrophobic polymer, cross-linking or pseudo-cross-linking as required, and insolubilizing in water.

For the cross-linking, it is preferable to carry out a cross-linking reaction using the reactive functional groups of the hydrophilic polymer and the hydrophobic polymer.

The cross-linking reaction may be covalent cross-linking or ionic cross-linking.

Examples of the compound used for the crosslinking reaction include known polyfunctional compounds having a crosslinking property, such as polyepoxy compounds, polyisocyanate compounds, poly (meth) acrylic compounds, polymercapto compounds, polyalkoxysilyl compounds, Polyvalent metal salt compounds, polyamine compounds, aldehyde compounds, polyvinyl compounds, hydrazine and the like, and the crosslinking reaction is performed by adding a known catalyst,
The reaction is promoted.

In preparing an aqueous emulsion which is preferably used as the hydrophobic polymer of the present invention, the copolymerizable components include reactive functional groups such as carboxyl group, hydroxyl group, methylolamide group, epoxy group, arbonyl group and amino group. And a method of forming a crosslinked structure using the above-mentioned polyfunctional compound as a crosslinking agent.

Specific examples of known cross-linkable polyfunctional compounds include the following compounds.

(1) Sublimated sulfur, by-product sulfur produced by oxidizing hydrogen sulfide, colloidal sulfur produced by oxidizing hydrogen sulfide in a wet manner, and the like. Also, thiuram-based compounds such as dithiomorpholine, thioplasttetramethylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide, which decompose when heated to generate sulfur, piperidine pentamethylenethiocarbamate, pipecoline pipecolic Dithiocarbamate compounds such as rudithiocarbamate, sodium dimethyldithiocarbamate, xanthate compounds such as sodium isopropylxanthate, zinc butylxanthate, thiourea compounds such as thiourea and thiocarbanilide, zinc salts of thiazoles such as diphenylguanidine, and mercaptobenzothiazole Sodium salt, dibenzothiazyl disulfide, cyclohexylamine salt of mercaptobenzothiazole Such as thiazole-based compound.

(2) Aldehydeamine compounds such as butyraldehyde-monobutylamine condensate, butyraldehyde-aniline condensate, heptaldehyde-aniline reactant, salt ethyl-formaldehyde-ammonia reactant, zinc oxide, tellurium, selenium, Ammonia zirconium carbonate and organic peroxides such as benzoyl peroxide and dicumyl peroxide.

Further, examples of the crosslinking accelerator include zinc carbonate, stearic acid, oleic acid, lauric acid, zinc stearate, dibutylammonium oleate, diethanolamine, triethanolamine, diethylene glycol and the like.

(3) Polyepoxy compounds, urea resins, polyamines, melamine resins, benzoguanamine resins, acid anhydrides and the like.

Specific examples of the polyepoxy compound include glycerin dipolyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether and the like. Is mentioned.

Specific examples of polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine,
And polyamidoamine.

(4) Polyisocyanate compounds and the like.

Examples of the polyisocyanate compound include:
Tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane isocyanate, liquid diphenylmethane diisocyanate, polymethylene polyphenylisocyanate, xylylene diisocyanate, cyclohexyl diisocyanate, cyclohexanephenylene diisocyanate, naphthalene-1,5-diisocyanate, isopropylbenzene-2,4-diisocyanate, polypropylene Glycol / tolylene diisocyanate addition reactants.

These crosslinking agents can be used alone or as a mixture of two or more. Water is mainly used as the dispersion medium, but a known organic solvent can be added as necessary. As a method of adding the organic solvent, a method of adding as a polymerization solvent and a method of adding as a mixed solvent to an emulsion solution after emulsion polymerization are possible.

As a method for mixing the hydrophilic polymer and the hydrophobic polymer of the hydrophilic swelling layer of the present invention, a method of kneading using a mixer such as a roll mixer such as a three-roller, a kneader, a homogenizer, a ball mill or the like can be used. The mixing is preferably carried out by a known method used for producing a paint or putty, such as a method of wet mixing and dispersing using a disperser.

As a method for forming the hydrophilic swelling layer of the present invention, since an aqueous emulsion is preferably used as a hydrophobic polymer, each component (hydrophilic polymer, hydrophobic polymer, etc.) is mixed in an aqueous solution system, A method in which a crosslinking agent is added as necessary is preferable from the viewpoint of realizing a homogeneous phase separation structure and improving ink repulsion.

Therefore, it is particularly preferable to use a water-soluble polyfunctional compound as the crosslinking agent. That is, it is preferable to use a water-soluble polyepoxy compound, polyamine compound, melamine compound, or the like.

Next, the phase separation structure of the hydrophilic swelling layer according to the present invention will be described.

By adopting a phase separation structure composed of a phase mainly composed of a hydrophilic polymer and a phase mainly composed of a hydrophobic polymer, both ink repellency and printing durability can be realized in a wide composition range. It becomes possible.

The composition ratio of the hydrophilic polymer phase and the hydrophobic polymer phase constituting the phase-separated structure is free. (1) Either one is a continuous phase and the other is a dispersed phase, (2) hydrophilic (3) A form in which both the hydrophilic and hydrophobic polymer phases have a continuous phase and a dispersed phase, respectively.

Examples of the phase separation structures (1) to (3) are shown in FIGS.

That is, when a material whose hydrophilic polymer shows relatively strong hydrophilicity (such as a water-soluble polymer and a pseudo-water-soluble polymer) is selected, the ratio of the hydrophilic polymer contained in the hydrophilic swelling layer is determined by the ink repellency. In addition, a relatively small amount is sufficient from the viewpoint of printing durability, and the ratio of the hydrophobic polymer is relatively large, so that the above-mentioned form (1) or (2) having a hydrophilic polymer as a dispersed phase is obtained. Is preferred. On the other hand, when a material whose hydrophilic polymer shows relatively weak hydrophilicity (such as a water-swellable polymer) is selected, the ratio of the hydrophilic polymer contained in the hydrophilic swelling layer is determined in terms of ink repellency and printing durability. From a relatively large amount, and the proportion of the hydrophobic polymer is relatively small.
It is preferable to take the form of (2) or (3).

That is, the preferable phase separation structure of the hydrophilic swelling layer used in the present invention depends on the rubber elasticity and water swelling property of the layer, but differs depending on the degree of hydrophilicity of the hydrophilic polymer.

In the case of the form (1), in order that the hydrophobic polymer phase is mainly a continuous phase, the composition of the hydrophobic polymer is 50% by weight or more, preferably 60 to 95% by weight. More preferably, it is 70 to 90% by weight. When the composition ratio of the hydrophobic polymer is 50% by weight or less, the performance of the hydrophilic swelling layer as an ink repellent layer is improved in the initial stage of printing, but the printing durability tends to sharply decrease. On the other hand, when the composition ratio of the hydrophobic polymer exceeds 95% by weight, the hydrophilic polymer in the hydrophilic swelling layer cannot absorb water sufficiently, and the hydrophilicity is insufficient, and the ink repellency tends to be extremely reduced.

In the case of the forms (2) and (3), both the hydrophilic polymer and the hydrophobic polymer are at least 20% by weight, preferably at least 40% by weight.

The hydrophilic swelling layer preferably has rubber elasticity.

The rubber elasticity of the hydrophilic swelling layer is characterized by the value of the initial elastic modulus measured by the method described below.

[Method of measuring initial elastic modulus of hydrophilic swelling layer]
A solution having the same composition as that of the hydrophilic swelling layer of the photosensitive lithographic printing plate precursor to be measured is spread on a Teflon dish and dried and cured at 60 ° C. for 24 hours. The obtained dried and cured film was 40 mm long and 1.95 wide using a razor blade or the like.
It is cut into strip-shaped test pieces having a thickness of about 0.2 mm and a thickness of about 0.2 mm.

The obtained test piece was kept at 25 ° C. before measurement.
After allowing to stand for 24 hours or more in a 50% RH environment and controlling the humidity, the thickness was measured with a micro gauge, and the initial elastic modulus was measured under the following tensile conditions. Data processing is JIS K6
301.

Tensile speed 200 mm / min Distance between chucks 20 mm Number of repetitions 4 times Measuring machine “RTM-100” Tensilon universal testing machine (manufactured by Orientec Co., Ltd.) Hydrophilic swelling used in the photosensitive lithographic printing plate precursor of the present invention The initial elastic modulus of the layer is preferably in the range of 0.01 to 10 kgf / mm ² from the viewpoint of ink repellency and shape retention. More preferably, 0.01 to 5 kgf / m
m ² , and more preferably 0.01 to ² kgf / mm ² .

That is, the initial elastic modulus is 0.01 kgf /
If it is less than ² mm, the shape retention of the hydrophilic swelling layer is extremely reduced, and the durability during printing tends to be extremely reduced.

On the other hand, if the initial elastic modulus is more than 10 kgf / mm ² , rubber elasticity becomes insufficient and ink repellency tends to be extremely reduced.

The hydrophilic swelling layer used in the present invention preferably has a specific value of the water swelling ratio measured according to the following definition.

[0132]

(Equation 1) Here, the water absorption means a value measured according to the following definition.

Water absorption (g / m ² ) = W _WET −W _DRY W _DRY : Weight in dry state (g / m ² ) W _WET : Weight (g) after immersion in water at 25 ° C. × 10 minutes
/ M ² ) [Method of measuring water absorption] The photosensitive lithographic printing plate precursor to be measured is cut into a predetermined area and immersed in purified water at 25 ° C. After immersion for 10 minutes, excess water adhering to the front and back surfaces of the hydrophilic swelling layer of the original plate was quickly wiped off with “Hize Gauze” (cotton cloth: manufactured by Asahi Kasei Kogyo Co., Ltd.),
The swelling weight W _WET of the _master is weighed. Thereafter, the master is dried in an oven at 60 ° C. for about 30 minutes to obtain a dry weight W
Weigh _DRY .

The hydrophilic swelling layer used in the present invention can have a water swelling ratio of 10 to 1000%.
From the viewpoints of ink repellency and shape retention, the content is preferably 50 to 500%. When the water swelling ratio is less than 10%, the ink repellency tends to be extremely reduced, and defects such as pinholes are liable to occur during coating. Also 10
If it exceeds 00%, the shape retention tends to be extremely reduced.

The thickness of the hydrophilic swelling layer referred to in the present invention is a value measured by a gravimetric method after peeling off the coating layer of the hydrophilic swelling layer of the dried photosensitive lithographic printing plate precursor coated on the substrate. means. The thickness of the hydrophilic swelling layer was measured according to the following equation.

Thickness of hydrophilic swelling layer (g / m ² ) = (W−W ₀ ) / α W: dry weight of photosensitive lithographic printing plate precursor (g) W ₀ : release hydrophilic swelling layer from W Dry weight after falling off (g) α: Measured area of photosensitive lithographic printing plate precursor (m ² ) [Method of measuring hydrophilic swelling layer thickness] The photosensitive lithographic printing plate precursor to be measured has a predetermined area α. After cutting, it is dried in an oven at 60 ° C. for about 30 minutes, and the dry weight W is weighed. Thereafter, the original plate is immersed in purified water to swell the hydrophilic swelling layer, and the swelling layer is peeled off using a scraper or the like. The master from which the hydrophilic swelling layer was peeled off and dropped
Dry in an oven at 0 ° C. for about 30 minutes and weigh the dry weight W ₀ .

The hydrophilic swelling layer used in the present invention has a thickness of
It can be used at 0.1 to 100 g / m ² ,
From the viewpoints of ink repellency and shape retention, it is preferably 0.3 to 10 g / m ² . The thickness is 0.3 g / m ²
If it is less than 1, the ink repellency tends to be extremely reduced, and defects such as pinholes are likely to occur during coating. If it is 10 g / m ² or more, the shape retention during water swelling tends to deteriorate, which is economically disadvantageous.

Next, the protective layer of the present invention will be described.

On the surface of the hydrophilic swelling layer of the photosensitive lithographic printing plate precursor according to the invention, an appropriate protective layer is formed by coating on the surface of the hydrophilic swelling layer for the purpose of protecting the hydrophilic swelling. Laminating the film is performed. Further, the protective layer may contain a photobleaching substance for the purpose of protecting the photosensitive layer from light exposure (light other than the exposure light source, which means that light is originally irradiated to a non-irradiated portion). it can. In the present invention, since the hydrophilic swelling layer contains a lipophilic ethylenically unsaturated compound that can be extracted and removed by washing with water or the like, transfer from the master surface due to contact with other substances is prevented, and the hydrophilic swelling layer is exposed to light. It is preferable to form a protective phase in order to promote photocuring of the compound.

Specific examples of the protective film include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyethylene terephthalate, cellophane and the like. In addition, these protective films are subjected to unevenness processing, matte treatment of the surface, or a plastic layer containing silica particles or the like on the surface of the protective film in order to improve the vacuum adhesion in the flame during image exposure. Coating and lamination are also preferably performed.

Next, a method for producing a lithographic printing plate using the photosensitive lithographic printing plate precursor of the present invention will be described.

The photosensitive lithographic printing plate precursor according to the invention becomes a printing plate through a negative working plate making process. That is, the lipophilic ethylenically unsaturated compound present in the hydrophilic swelling layer formed on the substrate is exposed through the negative original film and the protective film located above the hydrophilic swelling layer.

The photosensitive lithographic printing plate precursor according to the present invention is obtained after the exposure.
The plate making is basically completed only by peeling off the protective film and washing the plate surface with water. The water used in the water washing step does not require any special additives, and only the plate surface is washed with tap water or the like.

In order to increase the efficiency of water washing, it is free to use a rinsing liquid supply and development accelerating means used in a known automatic developing machine such as spraying, showering, dipping, brushing and rubbing. Further, the temperature of the supplied water is not limited.

After the water washing treatment, it is preferable to wash with an oily solvent in order to completely remove the residue of the lipophilic ethylenically unsaturated compound extracted and removed from the plate surface.

As a specific example of the oily solvent, a paraffinic hydrocarbon, an isoparaffinic hydrocarbon, a cycloparaffinic hydrocarbon and an aromatic hydrocarbon are used singly or in a mixed form. Representative examples of these hydrocarbon solvents include fractionated petroleum products and reformed products thereof.

In the exposed area, the ethylenically unsaturated compound undergoes photocrosslinking and is fixed in the hydrophilic swelling layer. In the exposed area, when the hydrophilic swelling layer comes into contact with water, the photocrosslinked lipophilic component inhibits the water swelling property of the hydrophilic swelling layer, and reduces the rubber elasticity due to an increase in crosslink density, so that the ink It becomes an image part of flesh. On the other hand, the lipophilic ethylenically unsaturated compound present in the hydrophilic swelling layer in the unexposed part is easily removed from the hydrophilic swelling layer when the hydrophilic swelling layer comes into contact with water when the hydrophilic swelling layer swells with water. To form a non-image portion having a phase separation structure and water swelling property suitable for repelling the ink. The lipophilic ethylenically unsaturated compound extracted from the hydrophilic swelling layer at the portion corresponding to the non-image area by the water washing step is insoluble in water, and is therefore a known oil absorbing material (for example, “Toray WOSEP”). : Toray Industries, Inc.) can be easily adsorbed and separated by arranging it in a washing water drain.

As described above, the photosensitive lithographic printing plate precursor according to the present invention has a rubber having the phase separation structure of the ink-repellent hydrophilic swelling layer due to the photoreaction of the lipophilic ethylenically unsaturated compound of the photosensitive compound. An image is formed by forming a lipophilic image portion that changes elasticity and water swellability.

The light source used in the plate-making exposure step of the present invention includes, for example, a high-pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp and the like.

The substrate of the photosensitive lithographic printing plate precursor used in the present invention is not limited except that it is required to have flexibility that can be attached to an ordinary lithographic printing press and to withstand the load applied during printing. Absent.

Typical examples are aluminum, copper, iron,
And a plastic film such as a polyester film and a polypropylene film, or coated paper and a rubber sheet. Further, the substrate may be a composite of the above materials.

The surface of the substrate can be subjected to various surface treatments such as an electrochemical treatment, an acid-base treatment, and a corona discharge treatment for the purpose of improving plate inspection and adhesion.

It is also possible to form a primer layer on such a substrate by applying a coating or the like for the purpose of improving adhesiveness and preventing halation, thereby forming a substrate.

Next, a printing method using a printing plate prepared from the photosensitive lithographic printing plate precursor of the invention will be described.

For the lithographic printing of the present invention, a known lithographic printing machine is used. That is, sheet-fed and rotary printing machines of the offset and direct printing type are used.

After the photosensitive lithographic printing plate precursor according to the present invention has been subjected to image formation, it is mounted on a plate cylinder of these lithographic printing presses, and ink is supplied to the plate surface from an inking roller which comes into contact therewith. The non-image area having the hydrophilic swelling layer on the plate swells with the dampening solution supplied from the dampening solution supply device, and repels the ink. On the other hand, the image portion receives ink and supplies the ink to the surface of the offset blanket cylinder or the surface of the printing medium to form a printed image.

The fountain solution used for printing on a printing plate obtained from the photosensitive lithographic printing plate precursor according to the present invention contains water.
Of course, it is possible to use the etchant used in the plate, but it is possible to use pure water containing no additives.

When printing using the photosensitive lithographic printing plate of the present invention, it is preferable to use pure water having no additive.

Hereinafter, the present invention will be described in more detail by way of examples.

[0160]

【Example】

Examples 1 to 14 The following composition was applied to an aluminum plate having a thickness of 0.2 mm (manufactured by Sumitomo Light Metal Co., Ltd.), and then heat-treated at 150 ° C. for 60 minutes to give a hydrophilic swell having a thickness of ² g / m ^2. Layers were applied.

<Composition of hydrophilic swelling layer (parts by weight)> (1) 18 parts by weight of hydrophilic polymer (2) 5 parts by weight of tetraethylene glycol diglycidyl ether (3) 75 parts by weight of aqueous latex “JSR0596” [carboxy-modified styrene] -Butadiene copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.] (4) 2-aminopropyltrimethoxysilane 2 parts by weight (5) Purified water 900 parts by weight [Synthesis example of hydrophilic polymer] 60 g of vinyl acetate and acrylic A solution prepared by adding 0.5 g of benzoyl peroxide as a polymerization initiator to 40 g of an acid was dispersed in 300 ml of water containing 3 g of partially saponified polyvinyl alcohol and 10 g of NaCl as a dispersion stabilizer.

The dispersion was stirred at 65 ° C. for 6 hours to perform suspension polymerization. The methyl acrylate component of the obtained copolymer was identified from the NMR spectrum to be 48 mol%. The intrinsic viscosity in a benzene solution at 30 ° C. was 2.10.

Next, 8.6 g of the copolymer was added to a saponification reaction solution consisting of 200 g of methanol, 10 g of water and 40 ml of 5 NaOH, and the mixture was stirred and suspended.
After performing the saponification reaction for 1 hour, the temperature was raised to 65 ° C., and the saponification reaction was further performed for 5 hours.

The resulting saponification reaction product was sufficiently washed with methanol and freeze-dried. The degree of saponification was 98.3 mol%, and as a result of measurement of an infrared absorption spectrum, 1570 cm
^{At -1} , strong absorption attributed to the -COO ^- group was confirmed.

On the hydrophilic swelling layer coated as described above, a photosensitive composition having the composition shown in Table 1 below was applied.
Heat treatment at 00 ° C. for 3 minutes to obtain 0.5 g / m ^{2 of the} photosensitive composition.
Was impregnated into the hydrophilic swelling layer.

Thereafter, a 12-micron-thick biaxially stretched biaxially oriented polypropylene film was laminated using a calender roller so that the non-matted surface was in contact with the hydrophilic swelling layer, and a negative type lithographic printing plate precursor was used. I got

The obtained lithographic printing plate was subjected to PCW (PLATE CONTOROL WEDGE: manufactured by KALLE) using a high-pressure mercury lamp “Jetlight 3303kW: manufactured by Oak Manufacturing Co., Ltd.”
For 90 seconds through a negative film with
6 mW / cm ² ). Next, rinse the entire plate with tap water,
The unexposed portion of the photosensitive composition was washed to form a printing plate.

After the hydrophilic swelling layer corresponding to the ink repellent portion of the printing plate obtained in Example 3 was swollen with water, OsO ₄
It was stained and observed with a TEM (transmission electron microscope).

As a result of observation, it was found that the hydrophilic swelling layer had a phase separation structure composed of a phase mainly composed of a hydrophilic polymer and a phase mainly composed of a hydrophobic polymer as shown in FIG. confirmed. In addition, in the image area, it was confirmed that the lipophilic monomer that was photopolymerized by exposure was fixed and inhibited water swelling.

(1) 20 parts by weight of the monomers shown in Table 1 (2) 2 parts by weight of Michler's ketone (3) 2 parts by weight of 2,4-diethylthioxanthone (4) "Isopar E" (isoparaffinic hydrocarbon: Esso) 76 parts by weight

[Table 1] The obtained printing plate is a sheet-fed offset printing machine “Sprint 2”
5: Komori Corporation Co., Ltd. "
While supplying commercially available purified water as dampening water, use high quality paper (62.5
kg / chrysanthemum). The ink repellency and ink adhesion were evaluated by visually observing the printed matter. The initial elastic modulus and the water swelling ratio of the image portion and the non-image portion were measured according to the definitions. Table 2 shows the evaluation results.

[0171]

[Table 2] As described above, the rubber elasticity (initial elastic modulus) and water swelling ratio of the hydrophilic swelling layer in the portion corresponding to the non-image area are all the same as the blank (rubber elasticity and water swelling ratio were measured only for the hydrophilic swelling layer) As a result, it was confirmed that the lipophilic ethylenically unsaturated compound was completely extracted and removed.

Further, at the time when about 1,000 sheets were printed, no ink stain was generated on each printing plate, and a clear printed matter having a sufficient contrast was obtained.

Example 15 A planographic printing plate used in Example 1 and a normal PS plate (FPQ;
A plate obtained by exposing and developing a Fuji Photo Film Co., Ltd.) was mounted on the same plate cylinder, and printing was performed in the same manner as in Example 1 while supplying commercially available purified water as dampening water. went.

When the supply amount of the dampening solution is increased from the standard condition, the ink density of the image area is extremely reduced in the portion using the PS plate, and the ink deposition failure due to so-called “water loss” occurs. did. On the other hand, in the portion where the lithographic printing plate used in Example 1 was used, the degree of poor inking was slight.

Further, when the supply amount of the dampening solution was reduced from the standard condition, ink staining occurred on the entire surface of the portion using the PS plate. On the other hand, in the portion using the lithographic printing plate used in Example 1, good printed matter was obtained.

[0176]

The photosensitive lithographic printing plate precursor according to the present invention uses an lipophilic ethylenically unsaturated compound as a photosensitive component, so that it is excellent in the ink-inking property of the image area and can be basically prepared only by washing the plate surface with water. Plate making is possible.

The lithographic printing plate obtained from the original plate exhibits high ink repellency without performing a special surface treatment on a substrate necessary for exhibiting ink repellency in a conventional PS plate. Further, the ink can be efficiently repelled with a small amount of dampening water supplied, and the control range of the dampening water can be expanded. Further, printing can be performed without using a solvent such as isopropanol which is usually added to a fountain solution.

[Brief description of the drawings]

FIG. 1 shows an example of a phase separation structure of a hydrophilic swelling layer of a photosensitive lithographic printing plate precursor according to the present invention.

FIG. 2 shows an example of a phase separation structure of a hydrophilic swelling layer of a photosensitive lithographic printing plate precursor according to the present invention.

FIG. 3 shows an example of a phase separation structure of a hydrophilic swelling layer of a photosensitive lithographic printing plate precursor according to the present invention.

Claims (5)

(57) [Claims] 1. A photosensitive lithographic printing plate precursor comprising at least an ink repellent and light-sensitive hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer is lipophilic and ethylenic. Contains unsaturated compounds, and changes in ink adhesion by irradiation with actinic rays
The photosensitive lithographic printing plate precursor, characterized in that the reduction. 2. The hydrophilic swelling layer according to claim 1, wherein the hydrophilic swelling layer has a phase component composed of at least two phases of a phase mainly composed of a hydrophilic polymer and a phase mainly composed of a hydrophobic polymer. The photosensitive lithographic printing plate precursor described in the above. 3. The photosensitive lithographic printing plate precursor according to claim 1, further comprising a protective layer on the hydrophilic swelling layer. 4. The photosensitive lithographic printing plate precursor according to claim 1, wherein the plate surface is irradiated with actinic rays to cure the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer corresponding to the image area. And then removing the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer at the portion corresponding to the non-image area. 5. The method according to claim 4, wherein the lipophilic ethylenically unsaturated compound in the hydrophilic swelling layer corresponding to the non-image area is removed by washing the entire surface of the plate with water. Production method of lithographic printing plate.