JPH11291653A - Lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lithographic printing plate having an excellent ink repellency and high printing durability without desensitizing by sequentially providing a primer layer and a hydrophilic swelling layer on a base plate, incorporating a gelatin, casein or the like in the primer layer and incorporating a crosslinking structure therein. SOLUTION: A primer layer necessarily contains a protein and/or a synthetic resin and has a crosslinking structure. As the protein used for the primer layer, one or more protein selected from a gelatin, casein, albumin, or soybean protein. As the resin, a polyvinylether, polyvinyl pyrrolidone or the like is used. The structure may be crosslinked by modifying part of the protein and/or the resin by heating or the like or by using a crosslinker for forming the structure. The lithographic printing plate having a hydrophilic swelling layer using such a primer layer has excellent printing durability and good ink repellency even after printing many sheets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate, which has high ink repellency without desensitizing treatment, has a wide control range of dampening solution, and is free from dampening solution IPA. The present invention relates to a new lithographic printing plate that can be used.

[0002]

2. Description of the Related Art As a plate to be used for lithographic printing, a lipophilic photosensitive layer is applied on an aluminum substrate which has been subjected to a hydrophilic treatment, and the photosensitive layer remains on the image portion by a photolithography technique, while a non-image forming layer is formed. The line portion exposes the surface of the aluminum substrate and uses a dampening water layer on the surface to repel the ink, thereby using a PS plate with water to form an ink image and a silicone instead of the dampening solution. A waterless PS plate using a rubber layer as an ink repellent layer, a so-called waterless lithographic plate, is known.

[0003] The PS plate with water is a printing plate excellent in practical use. Usually, grained aluminum is used for the support, and a treatment such as anodizing the surface of the grain is performed as necessary. The improvement in the water retention of the dampening solution and the adhesion to the photosensitive layer are reinforced.

The PS plate with water is widely used due to its excellent printing characteristics (printing durability, image reproducibility, etc.), while the PS plate with water has such a complicated manufacturing process, Simplification is desired.

On the other hand, JP-A-8-282142, JP-A-8-282144, and JP-A-8-292558.
Japanese Patent Application Publication No. JP-A-2003-133873 discloses a lithographic printing plate having a hydrophilic swelling layer and having good ink repulsion, but further improving ink repellency, fountain solution tolerance, ink adhesion, and printing durability. There is a need for a lithographic printing plate material having the same.

[0006]

SUMMARY OF THE INVENTION The present inventors have high ink repellency without desensitizing treatment, have a wide tolerance of dampening solution, and can eliminate IPA without dampening solution. As a result of intensive study of a new lithographic printing plate with better ink repellency and high printing durability,
The present inventors have found that the intended purpose can be realized by introducing a primer layer made of a specific compound between the substrate and the hydrophilic swelling layer, and have reached the present invention.

[0007]

The present invention has the following arrangement.

(1) At least a primer layer on a substrate,
A lithographic printing plate sequentially provided with a hydrophilic swelling layer, wherein the primer layer contains one or more proteins selected from gelatin, casein, albumin and soy protein, and has a crosslinked structure. Print version.

(2) At least a primer layer on a substrate,
A lithographic printing plate sequentially provided with a hydrophilic swelling layer, wherein the primer layer is polyvinyl ether, polyvinyl pyrrolidone,
Polyacrylamide, polyvinyl phosphonic acid, phenolic resin, polyurethane, epoxy resin, polyester resin, phenoxy resin, polyvinyl butyral resin, amino resin, saponified vinyl acetate, vinyl acetate / (meth)
A lithographic printing plate comprising at least one synthetic resin selected from a saponified acrylate copolymer and having a crosslinked structure.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is necessary that a substrate, a primer layer and a hydrophilic swelling layer are provided in this order.

[0011] The primer layer of the present invention contains a protein and / or a synthetic resin.

The protein used in the primer layer of the present invention may be one or more proteins selected from gelatin, casein, albumin, and soybean protein.

[0013] Gelatin is composed of α-amino acids and imino acids linked by peptide bonds,
It is a soluble protein obtained by treating collagen, the main protein component forming the skin, bones, tendons and the like of mammals, with acid, alkali or hot water. There are many types of amino acids and imino acids that constitute gelatin, and various compositions can be obtained depending on the purification conditions.Also, there are considerable differences depending on the raw materials, but any one can be used for the primer layer of the present invention. Can be.

Casein is a high molecular compound in which amino acids are linked in a long chain by peptide bonds, and its industrial production methods include natural fermentation (casein lactate), coagulation with sulfuric acid (casein sulfate), and coagulation with hydrochloric acid. Method (casein hydrochloride), rennet method (rennet casein) and the like, and casein produced by any method may be used.

In addition, proteins such as soybean protein (vegetable casein) having properties similar to casein and albumin, which is a blood protein contained in plasma in a large amount, can also be used in the primer layer of the present invention.

The synthetic resin used for the primer layer of the present invention includes polyvinyl ether, polyvinyl pyrrolidone,
Polyacrylamide, polyvinyl phosphonic acid, phenolic resin, polyurethane, epoxy resin, polyester resin, phenoxy resin, polyvinyl butyral resin, amino resin, saponified vinyl acetate, vinyl acetate / (meth)
One or more synthetic resins selected from saponified acrylate copolymers can be mentioned.

As the polyvinyl ether, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl isobutyl ether and the like are preferably used.

It is necessary that the primer layer of the present invention contains the above-mentioned protein and / or synthetic resin and has a crosslinked structure. The crosslinked structure may be formed by denaturing a part of the protein and / or the synthetic resin by a method such as heating to form a crosslink, or using a crosslinker that reacts with the protein and / or the synthetic resin to form a crosslinked structure. Good.

The crosslinking reaction may be covalent crosslinking or ionic crosslinking.

Examples of the compound used for the crosslinking reaction include known polyfunctional compounds having crosslinking properties, such as polyepoxy compounds, polyisocyanate compounds, poly (meth) acrylic compounds, polymercapto compounds, polyalkoxysilyl compounds, Examples include a polyvalent metal salt compound, a polyamine compound, an aldehyde compound, and a polyvinyl compound. The crosslinking reaction is carried out by adding a known catalyst to accelerate the reaction.

It is also preferable to add, for example, a silane coupling agent, an organic titanate or the like as an anchor agent constituting the primer layer. A white pigment or a yellow pigment such as titanium oxide, calcium carbonate, or zinc oxide may be added for the purpose of preventing halation from the substrate and improving plate inspection. It is also optional to add a surfactant or the like for the purpose of improving coatability. These resins may be used alone or as a mixture of two or more, and if necessary, an epoxy compound, an isocyanate compound,
A known crosslinking agent such as a blocked isocyanate compound is added.

Next, the hydrophilic swelling layer of the present invention will be described.

The non-image area of the lithographic printing plate according to the present invention is characterized in that it comprises a hydrophilic swelling layer.

The hydrophilicity as used in the present invention means a property that is substantially insoluble in water and exhibits water swelling property. A known hydrophilic polymer is laminated on a substrate by coating or transferring. A hydrophilic swelling layer which is cross-linked or pseudo-cross-linked using the method described above and insolubilized in water to make water swellable is used.

As used herein, the term "hydrophilic polymer" means a known water-soluble polymer (which means completely soluble in water) or a pseudo-water-soluble polymer (which means amphipathic. Means water-swellable polymer (means 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.

In the present invention, known polymers can be used as the hydrophilic polymer, and include animal polymers, plant polymers, and synthetic polymers. For example, "Function
alMonomers "(by Y. Nyquist, De.
kker), "Water-soluble polymer" (by Nakamura, Chemical Industry Co., Ltd.), "Latest processing / modification technology and application development of water-soluble polymer water-dispersed resin, Comprehensive technical materials" (Management Development Center Publishing Division), Examples include hydrophilic polymers described in "Applications and Markets of New Water-Soluble Polymers" (CMC).
Specific examples are described below.

(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, ammonium polyacrylate, sodium polyacrylate, polyammonium methacrylate, N-vinyl carboxylic acid-based polymer,
Acrylic acid-based copolymer, acrylic emulsion copolymer, polyvinyl alcohol-based crosslinked polymer, sodium polyacrylate-based crosslinked product, saponified polyacrylonitrile-based polymer, hydroxyethyl (meth) acrylate-based polymer ((meth) □□□□ means □
□□□ or meta □□□□. ), Poly (vinyl methyl ether-co-maleic anhydride), maleic anhydride copolymer, vinylpyrrolidone copolymer,
Polyethylene glycol di (meth) acrylate-based crosslinked polymers, polypropylene glycol di (meth) acrylate-based crosslinked polymers, and the like.

The above-mentioned hydrophilic compound may contain 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 changed. is there.

Next, a method for crosslinking a hydrophilic polymer will be described.

The hydrophilic swelling layer is formed by crosslinking or pseudo-crosslinking at least one of the above hydrophilic polymers as necessary.
A layer is formed on the substrate by insolubilizing in water. Usually, the cross-linking reaction is performed by performing a three-dimensional cross-linking reaction using a reactive functional group of the hydrophilic polymer.

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

Examples of the compound used in the crosslinking reaction include known polyfunctional compounds having crosslinking properties, such as polyepoxy compounds, polyisocyanate compounds, poly (meth) acrylic compounds, polymercapto compounds, polyalkoxysilyl compounds, Examples include a polyvalent metal salt compound, a polyamine compound, an aldehyde compound, and a polyvinyl compound. The crosslinking reaction is carried out by adding a known catalyst to accelerate the reaction.

These hydrophilic polymers can be used alone or as a mixture of two or more kinds for the purpose of maintaining the form of the hydrophilic swelling layer and adjusting the water swelling property, and blending the non-hydrophilic polymer. It is also possible.

The hydrophilic swelling layer may be provided with various heat histories by applying a heat treatment at the time of coating or after coating. In this case, even if the constituent components of the hydrophilic swelling layer are the same, water swelling properties such as water absorption and water absorption may change due to the heat history.

For the purpose of improving the adhesion to the lower layer, a known silane coupling agent, an isocyanate compound, a catalyst or the like may be added, or an intermediate layer may be provided.

The hydrophilic swelling layer used in the present invention preferably has a specific range of water absorption calculated according to the following method.

Water absorption (g / m ² ) = W _WET −W _DRY W _DRY : Weight in dry state (g / m ² ) W _WET : Weight after immersion in water at 25 ° C. × 10 minutes (g)
/ M ² ) [Method of measuring water absorption] A non-image area of a lithographic printing plate to be measured is cut into a predetermined area and immersed in purified water at 25 ° C. After immersion for 10 minutes, the excess liquid adhering to the hydrophilic swelling layer surface and the back surface of the printing plate was washed with "Hize gauze"
(Cotton cloth: manufactured by Asahi Kasei Kogyo Co., Ltd.), and the swelling weight W _WET of the printing plate is weighed. Thereafter, the printing plate is dried in an oven at 60 ° C. for about 30 minutes, and the dry weight W _DRY is weighed.

The water absorption of the non-image area composed of the hydrophilic swelling layer of the present invention is 1 from the viewpoint of ink repulsion and form retention.
５０50 g / m ² , preferably 2-40 g / m ^2
2 , more preferably 3 to 30 g / m ² .

Further, the hydrophilic swelling layer of the present invention preferably has a water absorption value measured according to the following definition within a specific range.

Water absorption (%) = water absorption (g / m ² ) / hydrophilic swelling layer thickness (g / m ² ) × 100 where the hydrophilic swelling layer thickness was applied on the substrate. The value refers to a value measured by a gravimetric method after the coating layer of the hydrophilic swelling layer corresponding to the non-image area of the dried lithographic printing plate is peeled off. The thickness of the hydrophilic swelling layer was measured according to the following equation.

The thickness of the hydrophilic swelling layer (g / m ² ) = (W−
W ₀ ) / α W: Dry weight (g) of a lithographic printing plate obtained by cutting a portion formed only of the non-image area W ₀ : Dry weight (g) after peeling off the hydrophilic swelling layer from W and dropping it off ) Α: Measurement area of lithographic printing plate (m ² ) [Method of measuring hydrophilic swelling layer thickness] A portion formed only of the non-image portion of the lithographic printing plate to be measured has a predetermined area α.
After drying in an oven at 60 ° C. for about 30 minutes, the dry weight W is weighed. Thereafter, the lithographic printing 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 lithographic printing plate from which the hydrophilic swelling layer has been peeled off is again dried in an oven at 60 ° C. for about 30 minutes, and the dry weight W ₀ is weighed.

The water absorption of the non-image area (ink repelling portion) comprising the hydrophilic swelling layer of the present invention is preferably from 10 to 2000%, and more preferably from 50 to 1700%, from the viewpoint of ink repulsion and form retention. And more preferably in the range of 50 to 700%. When the water absorption is less than 10%, the ink repellency of the non-image area is reduced. On the other hand, when the water absorption of the non-image area is more than 2000%, the non-image area has low shape retention, so that the non-image area has a low shape retention. The image area is easily damaged.

The hydrophilic swelling layer of the present invention preferably has rubber elasticity. That is, the initial elastic modulus of the hydrophilic swelling layer calculated by the following method is preferably within a specific range.

[Method of Measuring Initial Elastic Modulus] A solution having the same composition as the portion corresponding to the non-image area of the lithographic printing plate is spread on a Teflon dish and dried at 60 ° C. for 24 hours. The obtained dried and cured film is 40 mm long using a razor blade or the like.
The test piece is cut into a rectangular test piece having a width of 1.95 mm and a thickness of about 0.2 mm.

The obtained test piece was heated at 25 ° C. before measurement.
After standing for 24 hours or more in an environment of × 50% RH and adjusting 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 K
Performed according to 6301.

Tension speed 200 mm / min Distance between chucks 20 mm Number of repetitions 4 times Measurement device “RTM-100” (manufactured by Orientec Co., Ltd.) The initial elastic modulus of the hydrophilic swelling layer is 0.01 to 10 kgf /
mm ² is important from the viewpoint of ink repulsion and form retention, and is 0.01 to 5 kgf / mm.
² is preferable, and the range of 0.01 to ² kgf / mm ² is more preferable. Initial elastic modulus is 0.01kgf / mm
If less than ^2, the shape retention of the hydrophilic swelling layer is reduced,
Poor print durability, initial elastic modulus 10 kgf / mm ²
If it is larger than the above, the ink repellency is extremely reduced.

The hydrophilic swelling layer used in the present invention preferably has a water swelling ratio calculated according to the following method in a specific range.

Water swelling ratio (%) = (Θ _WET −Θ _DRY ) / Θ _DRY × 100 Θ _DRY : Thickness (μm) of hydrophilic swelling layer composed of non-image area or image area in dry state Θ _WET : Thickness (μm) of non-image area or hydrophilic swelling layer composed of image area in swelling state [Method of measuring water swelling rate (A)] Cross-section of lithographic printing plate including non-image area to be measured Then, a slice is prepared by cutting. After vacuum-drying this section at room temperature for one day and night, the thickness of the hydrophilic swelling layer at the site is observed with an optical microscope, and this is defined as _ΘDRY (μm). The observation with an optical microscope was performed quickly in an environment of 23 ° C. and 20% RH.

Further, an excess water droplet was placed on the lithographic printing plate section, the section was observed with an optical microscope in a state where the hydrophilic swelling layer was sufficiently swollen with water, and the thickness of the hydrophilic swelling layer at the site was read.と_する_WET (μm).

[Measurement method of water swelling ratio (B)] The non-image area of the lithographic printing plate to be measured was exposed to an OsO ₄ aqueous solution for one day and night to fix the hydrophilic swelling layer with OsO ₄ . An ultrathin section is prepared by cutting with a microtome so that a predetermined portion has a cross section. The thickness of the hydrophilic swelling layer at the site is observed with a transmission electron microscope (TEM) at a magnification of about 10,000 to 50,000 times, and this is defined as Θ _DRY (μm).

On the other hand, the planographic printing plate to be measured is
It is immersed in an O ₄ aqueous solution for 2 to 3 days to solidify / fix the hydrophilic swelling layer in a water swelling state. An ultra-thin section is prepared by cutting with a microtome so that a predetermined portion has a cross section, and the thickness of the hydrophilic swelling layer of the portion is determined by a transmission electron microscope (TEM) at a magnification of about 10,000 to 50,000 times. And read this,
_WET (μm).

The water swelling ratio of the non-image area (ink repelling portion) comprising the hydrophilic swelling layer of the present invention is preferably from 10 to 2,000% from the viewpoint of ink repellency and form retention, and is preferably from 50 to 1700. %, More preferably in the range of 50 to 700%. When the water swelling ratio is less than 10%, the ink resilience of the non-image portion decreases, while when the water swelling ratio of the non-image portion exceeds 2000%, the non-image portion has poor shape retention and printing. Sometimes, the non-image area is easily damaged.

Next, an example of the method for producing a lithographic printing plate according to the present invention will be described, but the present invention is not limited thereto.

The image of the lithographic printing plate of the present invention can be formed, for example, by irradiating the plate surface of a photosensitive lithographic printing plate precursor having a primer layer and a hydrophilic swelling layer on a substrate with actinic rays. .

The actinic rays referred to herein include high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, fluorescent lamps and other ultraviolet light to visible light, semiconductor lasers, YAG
Lasers, argon ion lasers, helium neon lasers, helium cadmium lasers, carbon dioxide lasers, visible light to infrared light such as light emitting diodes.

A known photosensitive compound is used for such image formation.

Examples of known photocrosslinkable or photocurable photosensitive compounds include the following specific examples (1) to (5).

(1) Photopolymerizable monomer or oligomer alcohols (ethanol, propanol, hexanol, octanol, cyclohexanol, glycerin,
(Meth) acrylic acid such as trimethylolpropane, pentaerythritol, isoamyl alcohol, lauryl alcohol, stearyl alcohol, butoxyethyl alcohol, ethoxyethylene glycol, methoxyethylene glycol, methoxypropyl glycol, phenoxyethanol, phenoxydiethylene glycol, tetrahydrofurfuryl alcohol, etc. Esters, carboxylic acids (acetic acid, propionic acid, benzoic acid, acrylic acid,
Methacrylic acid, succinic acid, maleic acid, phthalic acid, tartaric acid, citric acid, etc.) and glycidyl (meth) acrylate, m-xylylenediamine, addition reaction of benzylamine with glycidyl (meth) acrylate Compounds, amide derivatives (acrylamide, methacrylamide, N-
Methylolacrylamide, methylenebisacrylamide, etc.), and addition products of epoxy compounds with (meth) acrylic acid.

(2) Photodimerizable photosensitive resin composition A photosensitive layer containing, for example, polyvinyl cinnamate, such as p
A 1: 1 polycondensation unsaturated polyester of phenylenediacrylic acid and 1,4-dihydroxyethyloxycyclohexane, a photosensitive polyester derived from cinnamylidenemalonic acid and bifunctional glycols, polyvinyl alcohol Cinnamate esters of hydroxyl-containing polymers such as starch, starch, cellulose and the like.

(3) A composition comprising a combination of a monomer, oligomer or polymer having an epoxy group and a known photoacid generator. When exposed to light, the photoacid generator generates a Lewis acid or a Bronsted acid. The groups crosslink by cationic polymerization.

(4) Composition of monomer, oligomer or polymer having an allyl group and / or vinyl group and monomer, oligomer or polymer having a mercapto group. When exposed, the mercapto group is added to the allyl group and / or the vinyl group. Crosslink.

(5) Composition of a diazonium salt compound and a hydroxyl group-containing compound A diazo resin represented by a condensate of p-diazodiphenylamine and formaldehyde, and the like can be mentioned.

Specific examples include those described in JP-B-47-1167 and JP-B-57-43890.

(6) Polyisoprene rubber or polybutadiene rubber cyclized with a bis azide compound, or a photosensitive composition containing cresol novolak resin as a main component. These photosensitive compounds form a hydrophilic swelling layer on a substrate. When the photosensitive composition is added to the composition and allowed to exist in the layer, or after forming a hydrophilic swelling layer, the photosensitive composition is applied on the layer and impregnated into the layer. .

Further, a known photosensitizer can be added to the hydrophilic swelling layer of the original plate for the purpose of sensitizing these photosensitive compounds.

Further, a dye or pigment,
It is also possible to add trace amounts of various additives such as a pH indicator, a leuco dye, a surfactant and an organic acid. In particular, it is preferable that the image area or the non-image area is dyed or faded in the plate making process.

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

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.

Next, a plate making method using the lithographic printing plate of the present invention will be described.

The planographic printing plate of the present invention can be made into a printing plate through a plate making process for negative working, for example. That is, the image is exposed through a negative original film by a normal exposure light source.

The light source used in this exposure step is
For example, a high-pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp and the like can be mentioned.

The planographic printing plate of the present invention can be a plate to be printed through so-called direct plate making using a laser. That is, image formation may be performed by irradiation with a laser beam.

After such exposure, rinsing with water or a developing solution, if necessary, dissolves and removes or unsensitizes the photosensitive compound present in the hydrophilic swelling layer in the unexposed area. A swellable non-image area is formed, and the photosensitive compound is photocrosslinked and cured in the exposed area.

Next, a printing method using the planographic printing plate of the present 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 forming an image on the lithographic printing plate of the present invention,
The lithographic printing press is mounted on a plate cylinder, and the plate surface is supplied with ink from an inking roller that comes into contact with the plate surface.

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 the lithographic printing plate of the present invention may be, for example, pure water containing no additive. Can be used.

When printing using the 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.

[0082]

Example 1 Example 1 Aluminum substrate 0.24 mm thick (Sumitomo Light Metal Co., Ltd.)
After applying a primer layer composition having the following composition to
Heat treatment was performed at 80 ° C. for 1 minute, and a primer layer having a dry weight of 1 g / m ² was applied.

<Primer layer composition (parts by weight)> (1) “Nipporan 3124” (manufactured by Nippon Polyurethane Co., Ltd.) 20 parts by weight (2) “Coronate L” (manufactured by Nippon Polyurethane Co., Ltd.) 10 parts by weight ( 3) Butyl acetate 100 parts by weight (4) Methyl ethyl ketone 20 parts by weight Next, a hydrophilic swelling layer composition having the following composition was applied on the primer layer, and then heat-treated at 180 ° C. for 10 minutes to obtain a dry weight of 2.0 g / A hydrophilic swelling layer having a thickness of m ² was applied.

<Composition of hydrophilic swelling layer (parts by weight)> (1) 64 parts by weight of hydrophilic polymer [acrylamide-n-butyl methacrylate copolymer (weight composition ratio 50/50)] (2) Aqueous latex “JSR0596” 30 parts by weight [Carboxy-modified styrene-butadiene copolymer latex: manufactured by Nippon Gosei Rubber Co., Ltd.] (3) 6 parts by weight of 2-aminopropyltrimethoxysilane (4) 900 parts by weight of purified water Apply such a photosensitive layer composition,
Thereafter, heat treatment was performed at 100 ° C. for 2 minutes to apply and impregnate a photosensitive layer composition of 1.2 g / m ² to obtain a lithographic printing plate precursor.

<Photosensitive Layer Composition (Parts by Weight)> (1) Salt of paradiphenylamine condensed with paraformaldehyde: 25 parts by weight (2) Polyvinyl alcohol GL-05 (manufactured by Nippon Synthetic Chemical Co., Ltd.) 73 parts by weight ( 3) Vectria Pure Blue BOH (manufactured by Hodogaya Chemical Co., Ltd.) 2 parts by weight (4) Methyl cellosolve 900 parts by weight The obtained lithographic printing plate precursor is a high-pressure mercury lamp "Jetlight 330 3 kW; manufactured by Oak Manufacturing Co., Ltd." And P
90 seconds contact exposure (3.6 mW / cm) through a negative film with CW (PLATE CONTOROL WEDGE: manufactured by KALLE)
² ) I did. Next, the entire surface of the plate was rinsed with tap water, and the unexposed portion of the photosensitive layer composition was washed to obtain a printing plate.

The obtained printing plate was mounted on a sheet-fed offset printing press “Sprint 25: manufactured by Komori Corporation”, and then supplied with high-quality paper (62.5 kg / chrysanthemum) while supplying commercially available purified water as dampening water. ).

As an evaluation method, 10,000 sheets were printed under normal conditions, and the repulsion of the ink was visually determined on the 10,000th printed matter. In the non-image area, the image was evaluated as ○ when the image was a good image without background smear, and as × when background image was observed.

Example 2 An aluminum substrate having a thickness of 0.24 mm (manufactured by Sumitomo Light Metal Co., Ltd.)
After applying a primer layer composition having the following composition to
Heat treatment was performed at 20 ° C. for 1 minute, and a primer layer having a dry weight of 0.9 g / m ² was applied.

<Primer Layer Composition (Parts by Weight)> (1) Gelatin 30 parts by weight (2) Formaldehyde (30% aqueous solution) 2 parts by weight (3) Glyoxal (40% aqueous solution) 4 parts by weight (4) Purified water 564 Parts by weight The subsequent application of the hydrophilic swelling layer and the photosensitive layer and the plate making process were performed in the same manner as in Example 1 to obtain a lithographic printing plate, which was evaluated.

Examples 3 to 6 The resin components used in the primer layer composition of Example 1 were phenol resin "Super Beckasite 1001" (Nippon Reich Co., Ltd.), epoxy resin "Epicoat 828" Shell Chemical Co., Ltd., melamine Resin "Super Beckamine J8
20 "(Nippon Reich Co., Ltd.) and polyvinyl butyral resin (Sekisui Chemical Co., Ltd.) were carried out in the same manner as in Example 1 except that the film thickness was as shown in Table 1, and a lithographic printing plate was obtained. An evaluation was performed.

Examples 7 to 10 The resin component used in the primer layer composition of Example 2 was a saponified product of vinyl acetate "Gohsenol AL-06" (Nippon Synthetic Chemical Industry Co., Ltd.), vinyl acetate / methyl acrylate copolymer. Combined saponified product (synthesized by the method described in JP-A-8-234415), polyvinylphosphonic acid "PVPA"
(Manufactured by PANCHIM), polyvinylpyrrolidone "K-
120 "(Hanai Chemical Co., Ltd.), and the procedure was the same as in Example 1 except that the film thickness was as shown in Table 1. A lithographic printing plate was obtained and evaluated.

Comparative Example 1 A lithographic printing plate was prepared in the same manner as in Example 1 except that no primer layer was provided.

Table 1 summarizes the evaluation results.

[0094]

[Table 1] It can be seen that the lithographic printing plate provided with the hydrophilic swelling layer using the primer layer of the present invention has excellent printing durability and retains good ink repellency even after printing a large number of sheets.

[0095]

The planographic printing plate of the present invention has an excellent ink repellent layer and good printing durability.

Claims (2)

[Claims] 1. A lithographic printing plate comprising a substrate having at least a primer layer and a hydrophilic swelling layer in that order, wherein the primer layer contains one or more proteins selected from gelatin, casein, albumin, and soybean protein. And a lithographic printing plate having a crosslinked structure. 2. A lithographic printing plate comprising at least a primer layer and a hydrophilic swelling layer on a substrate in that order, wherein the primer layer is polyvinyl ether, polyvinyl pyrrolidone, polyacrylamide, polyvinyl phosphonic acid, phenol resin, polyurethane, epoxy resin. , Polyester resin,
It contains one or more synthetic resins selected from phenoxy resin, polyvinyl butyral resin, amino resin, saponified vinyl acetate, and saponified vinyl acetate / (meth) acrylate copolymer, and has a crosslinked structure. A lithographic printing plate characterized by having: