JPH1058636A - Original plate for laser-sensitive lithographic plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability for manufacturing an original plate for a printing plate and enable ink repellency equal to or higher than a PS lithographic plate to be displayed by generating the destructive absorption by a swelling layer through sensing of active light provided by a laser emission, in an original plate for a lithographic plate with a laser-sensitive hydrophilic swelling layer. SOLUTION: The master for a lithographic plate with a laser-sensitive hydrophilic swelling layer formed on a base has such a function that the hydrophilic swelling layer displays its destructive absorption through sensing of active light provided by a laser emission. Black pigment or black dye is in the ratio of 3-70wt.%, preferably, 5-50wt.% for the entire hydrophilic swelling layer in terms of solid base. If the ratio of the black substance exceeds 70wt.%, the ink repellency of the hydrophilic swelling layer is significantly deteriorated. However, if the ratio of the black substance is not more than 3wt.%, the sensitivity of the hydrophilic swelling layer to the laser emission is insufficient so that the ratio is not appropriate. The preferable coat thickness of the laser- sensitive hydrophilic swelling layer is 0.1-20g/m<2> .

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 precursor and, more particularly, to a novel laser-sensitive lithographic printing plate precursor capable of drawing digitally processed image information using a laser. .

[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. That is, as described in Teruhiko Yonezawa, "PS Plate Overview", Printing Society of Japan, publishing department (1993) pages 18 to 81, a lipophilic photosensitive resin layer is applied on an aluminum substrate that has been subjected to a hydrophilic treatment. According to the photolithographic technique, the photosensitive layer remains in the image area, while the non-image area exposes the surface of the aluminum substrate, and a dampening water layer is formed on the surface to repel ink, thereby forming an image forming water. There is a PS plate and a waterless PS plate using a silicone rubber layer as an ink repellent layer instead of a dampening solution layer, a so-called waterless planographic plate.

The term "waterless lithographic printing plate" as used herein means that the non-image area is made of a substance such as silicone rubber or a fluorine-containing compound which has ink repellency against oil-based ink used in normal lithographic printing. 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.

[0005] These PS plates are made into a printing plate through a plate making process based on a photolithography technique such as exposure and development through an original picture film. In recent years, instead of using the original picture film, a laser has been used as an alternative technique. There has been proposed a laser-sensitive lithographic printing plate in which digitally processed image information is directly drawn on a plate surface.

As a method of making a PS plate with water that requires dampening water into a laser-sensitive type, there are many proposals of a type in which a direct drawing is performed using a high-sensitivity photopolymer sensitive to a He-Ne or Ar laser. However, because of its high sensitivity, the handling of the plate material was poor, and a large-scale and expensive automatic exposure and development plate making apparatus was required.

On the other hand, as a method for making a waterless planographic printing plate a laser-sensitive type, for example, DE-A 2512038
The image formation is performed using a laser using a heat mode recording material in which a layer containing nitrocellulose and carbon black and a non-cured silicone layer are laminated on a support having or having a lipophilic surface. After that, a method has been proposed in which the exposed portion of the silicone layer is dissolved using a solvent such as naphtha and the other portion of the silicone layer is cured. However, this method is inconvenient in terms of environmental problems because it is difficult to handle the plate material during plate making, the curing step of the silicone layer is involved in the development step, and the use of an organic solvent causes inconvenience. Met.

In FR-A1473751,
A heat mode recording material using a layer having nitrocellulose, carbon black, and silicone on a substrate having a lipophilic surface has been proposed. After forming an image using a laser, the image forming portion becomes lipophilic. Is converted to However, this method has a poor ink-adhesive property because the silicone in the ink-impregnated portion is not removed from the plate surface.

[0009] In USP-5353705,
There has been proposed a heat mode recording material in which polyvinyl alcohol is laminated as an ink repellent layer on a laser sensitive layer composed of nitrocellulose and carbon black. However, the ink repellency was extremely insufficient even under a dampening water supply.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art. It is an object of the present invention to improve the plate making workability of a conventional laser-sensitive lithographic printing plate precursor. An object of the present invention is to provide a novel laser-sensitive lithographic printing plate precursor which has ink repellency equal to or higher than that of PS lithographic plates, and which can directly draw image information digitally processed using a laser on a plate surface.

[0011]

Means for Solving the Problems To solve the above problems, the present invention comprises the following constitutions.

(1) A lithographic printing plate precursor provided with at least a laser-sensitive hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer is sensitive to actinic rays by laser irradiation and causes destructive absorption. Features a laser-sensitive lithographic printing plate precursor.

(2) A lithographic printing plate precursor comprising at least a laser-sensitive hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer contains a black pigment or a black dye. Lithographic printing plate precursor.

(3) 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. ) The lithographic printing plate precursor described in the above.

(4) The laser-sensitive lithographic printing plate precursor as described in (2), further comprising a primer layer between the substrate and the hydrophilic swelling layer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The laser-sensitive lithographic printing plate precursor according to the present invention is provided with a laser-sensitive hydrophilic swelling layer in which the hydrophilic swelling layer undergoes destructive absorption in response to active light rays by laser irradiation. It is a lithographic printing plate precursor. In the present printing plate precursor, the hydrophilic swelling layer is in an unswelled state during laser irradiation and easily absorbs energy by actinic rays, and swells with fountain solution during printing to exhibit excellent ink repellency.

The hydrophilic swelling layer preferably contains a black pigment or a black dye from the viewpoint of destructive absorption of energy and easy introduction into the hydrophilic swelling layer.

The laser-sensitive lithographic printing plate precursor of the present invention is a lithographic printing plate precursor provided with a laser-sensitive hydrophilic swelling layer, wherein the hydrophilic swelling layer contains a black pigment or a black dye.

The black pigment of the present invention includes carbon black, aniline black, iron black, titanium black,
Pigment resin color (pigment resin printing agent) in which pigment and resin are mixed and dispersed. Carbon black is roughly classified into gas black, acetylene black and oil black depending on its raw material, and is roughly classified into channel black, furnace black, acetylene black and the like according to the production method, and any of them can be used.
Pigment resin color is water-in-oil type (W / O
Type) and oil-in-water type (O / W type). The W / O type comprises a paste in oil in which a pigment is dispersed in a solvent solution of a resin and a W / O type emulsion (extender) as a diluent. On the other hand, the O / W type is composed of a color base in which a pigment is dispersed in water with a surfactant (dispersant) and a stabilizer, and an O / W resin emulsion (binder) for fixing the pigment to a non-colored material. It consists of three components of an O / W emulsion for diluting and imparting printability. Any pigment resin color is not particularly limited.

The black dyes of the present invention are roughly classified into acid dyes, basic dyes, direct dyes, disperse dyes, reactive dyes, oil-soluble dyes and the like according to their dyeing modes. Good.

Preferred black dyes include acid dyes and basic dyes. Chromium as acid dye,
Copper, cobalt and other metal complex salt azo dyes, and as a basic dye, a polymethine dye having an amino group or a substituted amino group such as a quaternary ammonium salt, an azo dye, an azomethine dye, an anthraquinone dye, a triphenylmethane dye Etc. are particularly preferred.

Specific examples of metal complex salt azo dyes include Aizen spiron black BNH, MH, RLH, and BH.
Specific examples of the basic dye include Eizenkatilon black SBH, BXH, SH, NH, MH, AWH, KB
H (all above, Hodogaya Chemical Industry Co., Ltd.).

In the present invention, the ratio of the black pigment or the black dye to the entire hydrophilic swelling layer is 3 based on the solid content.
７０70% by weight, preferably 5-50% by weight. When the proportion of the black substance exceeds 70% by weight, the ink resilience of the hydrophilic swelling layer is remarkably reduced. On the other hand, when the proportion of the black substance is less than 3% by weight, the laser sensitivity is insufficient and is not suitable.

The thickness of the laser-sensitive hydrophilic swelling layer of the present invention is preferably from 0.1 to ²⁰ g / m ² , more preferably from 0.2 to 10 g / m ² . The film thickness is 0.1 g / m ²
If it is thinner, the sensitivity of the laser-sensitive layer decreases,
If the thickness is larger than g / m ² , excessive laser power is required, which is not practical.

The laser-sensitive hydrophilic swelling layer of the present invention contains the above-mentioned black pigment or black dye. Further, a known surfactant or dispersion stabilizer may be added from the viewpoint of compatibility and dispersibility with other components constituting the hydrophilic swelling layer. Further, a plasticizer, a wetting agent, a matting agent, an antioxidant, a flame retardant and the like may be added.

The hydrophilic swelling layer used in the present invention preferably 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.

The hydrophilicity in the present invention means the property of being substantially insoluble in water and exhibiting water swelling property. A known hydrophilic polymer is laminated on a substrate by coating or transfer, and the like. A hydrophilic swelling layer which is cross-linked or pseudo-cross-linked using the method described above and insolubilized in water to make it water-swellable is used.

The hydrophilic polymer mentioned here means a known water-soluble polymer (meaning one which is completely soluble in water), a pseudo-water-soluble polymer (meaning amphiphilicity, and macro-soluble in water. Micro means those containing undissolved parts),
Refers to water-swellable polymers (meaning those that swell in water but do 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
nal Monomers "(by Y. Nyquist,
Dekker), "Water-soluble polymer" (by Nakamura, Chemical Industry Co., Ltd.), "Latest processing and modification technology of water-soluble polymer water-dispersible resin and application development Comprehensive technical materials" (Management Development Center Publishing Department) Water-soluble polymers described in "Applications and Markets of New Water-Soluble Polymers" (CMC). Specific examples are shown 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-based graft polymer,
Starch-acrylamide-based graft polymer, carboxylated methylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, cellulose xanthate, cellulose-acrylonitrile-based graft polymer, cellulose-styrenesulfonic acid-based graft polymer, carboxymethylcellulose-based crosslinked product, hyaluronic Acid, agarose, collagen, milk casein, acid casein, rennet casein, ammonia casein, calicasein, 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, large Lecithin, pectin 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 polymer, poly (vinyl methyl ether-co-maleic anhydride), Maleic anhydride copolymer, vinylpyrrolidone copolymer, polyethylene glycol di (meth) acrylate crosslinked polymer, polypropylene glycol di (meth) acrylate crosslinked polymer, poly (N-vinylcarboxylic amide), N -Vinyl carboxylic acid amide copolymers, etc.

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.

Specific examples of the hydrophilic polymer preferably used in the present invention are shown below, but the present invention is not limited to these examples.

(1) maleic acid or maleic anhydride,
Maleic acid derivatives such as maleic amide or maleic imide and ethylene, propylene, butylene, isobutylene or diisobutylene having 2 to 12 carbon atoms;
Preferably, a crosslinked product of a reaction product of a copolymer with a linear or branched α-olefin having 2 to 8 carbon atoms and an alkali metal compound, an alkaline earth metal compound, ammonia, or an amine.

(2) A copolymer of maleic acid or a derivative thereof with a vinyl or vinylidene compound such as styrene, vinyl acetate, methyl vinyl ether, acrylate, methacrylate or acrylonitrile, and an alkali metal compound or an alkaline earth metal Crosslinked product of reaction product with compound, ammonia and amine.

(3) A crosslinked product of a reaction product of a copolymer of acrylic acid or methacrylic acid with the vinyl or vinylidene compound of the above (2), and an alkali metal compound, an alkaline earth metal compound, ammonia and an amine.

Polyoxyalkylene hydrophilic polymers disclosed in Japanese Patent Publication No. 58-37027, polyvinylpyrrolidone disclosed in Japanese Patent Application Laid-Open No. 60-104106, etc., and sulfonic acid groups as hydrophilic groups. Crosslinked products such as polystyrenesulfonic acid and acrylamidomethylpropanesulfonic acid copolymer
Polyurethane resins obtained by crosslinking a hydrophilic polymer having a hydroxyl group or an amino group with a polyisocyanate, which are disclosed in Japanese Patent No. 42416, and the like.

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

The hydrophilic swelling layer is formed on the substrate by cross-linking or pseudo-cross-linking at least one or more of the above-mentioned hydrophilic polymers as necessary, and insolubilizing in water. Crosslinking is performed by performing a crosslinking 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 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, a polyaldehyde compound, and a polyvinyl compound. The crosslinking reaction is carried out by adding a known catalyst to accelerate the reaction.

These hydrophilic polymers may be used alone or in combination with one another for the purpose of maintaining the shape of the hydrophilic swelling layer and adjusting the water swellability.
It can be used as a mixture of more than one species, and it is also possible to blend non-hydrophilic polymers.

For the purpose of improving the adhesion to the lower layer, it is also possible to add a known silane coupling agent, isocyanate compound, catalyst or the like or to provide an intermediate layer.

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 shape retention.
５０50 g / m ² , preferably 1-10 g / m ^2
2 , more preferably ² to 7 g / m ² .

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.

Tensile 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 / m
When it is less than m ^2, the shape retention of the hydrophilic swelling layer is reduced, the printing durability is poor, and the initial elastic modulus is 10 kgf / m.
When it is larger than m ² , the ink repulsion remarkably decreases.

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 rate (%) = (Θ _WET -Θ _DRY ) / Θ _DRY × 100 Θ _DRY : Thickness (μm) of hydrophilic swelling layer composed of non-image area in dry state Θ _WET : Non-swelling state Thickness (μm) of hydrophilic swelling layer composed of image area [Method of measuring water swelling rate (A)] Cut and slice so that a portion including a non-image area of a lithographic printing plate to be measured has a cross section. Is prepared. 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 this lithographic printing plate section, and 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) composed of the hydrophilic swelling layer of the present invention is preferably from 10 to 2000%, and from 50 to 1700, from the viewpoint of ink repulsion and form retention. %, 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.

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

The aqueous emulsion according to the present invention means an aqueous hydrophobic polymer suspension 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.

Among these aqueous emulsions, the hydrophobic polymers particularly preferably used in the present invention include styrene / butadiene system, acrylonitrile / butadiene system,
Latexes containing conjugated diene compounds such as methyl methacrylate / butadiene and chloroprene are mentioned.

The hydrophilic swelling layer of the present invention is formed on a substrate by mixing the hydrophilic polymer and the hydrophobic polymer, and crosslinking or pseudo-crosslinking as necessary, and insolubilizing the mixture in water.

For the crosslinking, it is preferable to carry out a crosslinking 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.

As a method of 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 when producing a paint or a 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 the 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 in the hydrophilic swelling layer of the present invention will be described.

By adopting a phase separation structure composed of a phase containing a hydrophilic polymer as a main component and a phase containing a hydrophobic polymer as a main component, both ink resilience and printing durability are 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 the hydrophilic and hydrophobic polymer phases have a continuous phase and a dispersed phase, respectively, can be freely selected from a form in which both the hydrophilic and hydrophobic polymer phases are continuous phases.

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

In the hydrophilic swelling layer used in the present invention, in addition to the above-mentioned hydrophilic polymer, hydrophobic polymer and optionally a crosslinking agent, a known antioxidant usually added in a rubber composition. , An antioxidant, an antiozonant, an ultraviolet absorber, a dye, a pigment, a plasticizer, and the like.

For the purpose of improving the adhesion to the lower layer,
Known silane coupling agents and isocyanate compounds,
It is also possible to add a catalyst or the like or to provide an intermediate layer between the substrate and the substrate.

The hydrophilic swelling layer used in the present invention can contain trace amounts of various additives such as dyes and pigments, pH indicators, leuco dyes, surfactants and organic acids. The substrate of the lithographic printing plate used in the present invention is not limited at all, except that it needs to be flexible and can withstand the load applied during printing, which is attached to a normal lithographic printing press.

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.

The plate making method of the laser-sensitive lithographic printing plate precursor according to the present invention will be described.

In the present invention, the laser sensitivity means that an image can be formed in a heat mode. In other words, the laser-sensitive layer and / or the ink repellent layer in the portion corresponding to the laser irradiation instantaneously cause destructive absorption such as combustion and / or evaporation, thereby forming an ink-filled concave portion.

As the concave portion of the ink-incorporating property, the substrate can be used as it is by exposing it as it is. However, in order to strengthen the adhesion between the substrate and the laser-sensitive layer, improve the ink-injecting property, and prevent halation. , A primer layer may be provided. Examples of the primer layer used in the present invention include those containing an epoxy resin as disclosed in JP-B-61-54219, polyurethane resin, phenol resin, acrylic resin, alkyd resin, and the like.
Polyester resin, polyamide resin, melamine resin, urea resin, benzoguanamine resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, polyvinyl butyral resin, ethylene-vinyl acetate copolymer, polycarbonate resin, polyacrylonitrile-butadiene copolymer , Polyether resin, polyether sulfone resin, milk casein, gelatin and the like. These resins can be used alone or in combination of two or more.

Among these, it is preferable to use a polyurethane resin, a polyester resin, an acrylic resin, an epoxy resin, a urea resin, or the like alone or as a mixture of two or more.

As the anchor agent constituting the primer layer, a known adhesive such as a silane coupling agent can be used, and an organic titanate is also effective.

It is optional to add a surfactant for the purpose of further improving the coatability.

In the case where the primer layer is exposed as an ink-filling concave portion and becomes an image area, an additive such as a dye or a pigment is contained in the primer layer to improve plate inspection. Is preferred. In this case, any dyes and pigments can be used as long as they have a different hue from that of the photosensitive layer, but green, blue, and violet dyes and pigments or white pigments are preferable.

The composition for forming the above primer layer is prepared as a composition solution by dissolving in a suitable organic solvent such as DMF, methyl ethyl ketone, methyl isobutyl ketone, dioxane and the like. A primer layer is formed by uniformly applying the composition solution on a substrate and heating it at a required temperature for a required time.

The thickness of the primer layer is 0.5 to 50 g / m
² is preferred, and more preferably 1 to 10 g / m ² . When the thickness is less than 0.5 g / m ² , the effect of blocking morphological defects and chemical adverse effects on the substrate surface is low, and the thickness is 50 g / m ^2.
If the thickness is larger than m ^2, it is disadvantageous from an economic viewpoint, so the above range is preferable.

The laser preferably used in the present invention includes a semiconductor laser, an Nd-YAG laser, an argon laser and the like, and a laser having a power output of 40 to 7500 mW is preferably used. Above all, from the point that heat mode recording is performed efficiently, 500 to 3000 m
A W semiconductor laser is preferably used.

Usually, the diameter of the ink-filled concave portion formed by one laser irradiation is about 3 to 100 μm.

Next, a printing method using a printing plate obtained from the laser-sensitive planographic 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 forming an image on the lithographic printing plate of the present invention by electrostatic transfer, these are mounted on a plate cylinder of a lithographic printing press, and ink is supplied to the plate surface from an inking roller which comes into contact with the plate.

The non-image area having the hydrophilic swelling layer on the plate swells with the dampening water supplied from the dampening water supply device and repels the ink. On the other hand, the image portion formed by the electrostatic transfer receives the 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 a lithographic printing plate having a hydrophilic swelling layer, which is drawn by the image forming method of the present invention, may be an etchant used in normal lithographic printing. Although possible, pure water without any additives can be used.

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

[0095]

【Example】

Examples 1-2 After coating the following composition on an aluminum plate (manufactured by Sumitomo Light Metal Co., Ltd.) having a thickness of 0.2 mm, a primer layer having a thickness of ² g / m ^{2 was obtained} by heating and curing at 200 ° C. for 5 minutes. Was applied.

<Primer layer composition (parts by weight)> (1) 20 parts by weight of a polyester resin "Vylon-200: manufactured by Toyobo Co., Ltd." (2) Melamine resin "Sumimar M-40S: manufactured by Sumitomo Chemical Co., Ltd." 10 parts by weight (3) 40 parts by weight of toluene (4) 10 parts by weight of methyl ethyl ketone (5) 30 parts by weight of butyl acetate (6) 50 parts by weight of cyclohexanone Next, carbon black (MA10
0: manufactured by Mitsubishi Kasei Kogyo Co., Ltd. (Example 1) and pigment resin color (Polux Black PM-B: manufactured by Sumika Color Co., Ltd.) (Example 2). After mixing the swelling layer composition, it was dispersed using a homogenizer, applied, and heat-treated at 180 ° C. for 2 minutes to form a laser-sensitive hydrophilic swelling layer having a thickness of 1.5 g / m ² .

[Synthesis Example of Hydrophilic Polymer] One liter of 4
A stirring rod, a thermometer, and a nitrogen inlet tube were attached to the open-mouth separable flask, and 100 g of N-vinylacetamide was added thereto.
Was dissolved in 280 g of deionized water. Nitrogen gas was introduced for about 10 minutes to drive out dissolved oxygen, raise the temperature of the solution to 30 ° C., and use 2,2 as a polymerization initiator.
20 g of a 5% aqueous solution of 2'-azobis-2-aminopropane dihydrochloride was added, and a polymerization reaction was carried out for about 10 hours. The viscosity of each polymer obtained was measured using a B-type viscometer (0.2% aqueous solution,
235c as a result of measuring at 30 ° C. and a rotation speed of 20 rpm)
ps.

<Laser-sensitive hydrophilic swelling layer composition (parts by weight)> (1) hydrophilic polymer 32 parts by weight (2) tetraethylene glycol diglycidyl ether 7 parts by weight (3) aqueous latex "DN-703" 49 parts by weight Part [Carboxy-modified acrylonitrile-butadiene copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.] (4) 10 parts by weight of black pigment (5) 2 parts by weight of dispersant (6) 900 parts by weight of purified water The surface of the presensitized lithographic printing plate precursor was irradiated with a semiconductor laser under the following conditions to form ink-adhered pixels.

Laser output: 1 W (800 nm) Spot diameter: 6 μm Pulse width: 10 μsec The laser-sensitive layer and the hydrophilic swelling layer in the portion corresponding to the laser irradiation were burned and destroyed, and removed, and 6.3 μm (Examples 1-2) Both of them have ink spotting pits having a spot diameter of (1).

A lithographic printing plate having such pits is mounted on a plate cylinder of a lithographic printing press together with a PS plate (FNS: manufactured by Fuji Photo Film Co., Ltd.), and ink is supplied from an ink forming roller which comes into contact with the plate surface. At the same time, printing was performed by supplying water from a dampening water supply device. As a result, the image area where the pits were formed received ink, and clear ink pixels corresponding to the pit diameter were formed on the printed matter via the offset blanket cylinder.

On the other hand, the hydrophilic swelling layer was swollen by the fountain solution, and a printed matter having the same contrast as that of the PS plate completely repelled by the ink was obtained. Even after the printing was completed for 5000 sheets, the hydrophilic swelling layer retained the ink repellency, and no ink stain was generated on the printed matter.

Examples 3 to 5 As black dyes, Spiron Black MH (manufactured by Hodogaya Chemical Industry Co., Ltd.) (Example 3), Katilon Black AWH
Using Hodogaya Chemical Industry Co., Ltd. (Example 4) and Nigrosine Base EX (Orient Chemical Industry Co., Ltd.) (Example 5), the composition of the laser-sensitive hydrophilic swelling layer was changed as follows. A laser-sensitive lithographic printing plate precursor was prepared in the same manner as in Example 1 except for the above.

<Laser-sensitive hydrophilic swelling layer composition (parts by weight)> (1) 26 parts by weight of the hydrophilic polymer of Example 1 (2) 7 parts by weight of tetraethylene glycol diglycidyl ether (3) aqueous latex “SX1503” 55 parts by weight [carboxy-modified acrylonitrile-butadiene copolymer latex: manufactured by Nippon Zeon Co., Ltd.] (4) 15 parts by weight of black dye (5) 2 parts by weight of 2-aminopropyltrimethoxysilane (6) 200 parts by weight of ethanol ( 6) 700 parts by weight of purified water As a result of laser irradiation under the same conditions as in Example 1, the laser-sensitive layer and the hydrophilic swelling layer in the portion corresponding to the laser irradiation were burned and destroyed, and were removed to 6.1 μm (Example 3). ), And ink-fillable pits having a spot diameter of 6.0 μm (Examples 4 and 5) were formed. Further, as a result of lithographic printing by supplying dampening water, the hydrophilic swelling layer showed the same ink repellency as in Example 1.

Comparative Examples 1-2 A printing plate precursor was prepared in exactly the same manner as in Examples 1 and 3, except that no black pigment or black dye was used. Laser irradiation was performed under the same conditions as in Example 1. In each case, no pits were formed on the hydrophilic swelling layer, and no burning destruction of the hydrophilic swelling layer by laser was observed.

[0105]

The laser-sensitive lithographic printing plate of the present invention is
Having an ink repellent layer composed of a laser-sensitive hydrophilic swelling layer, it has excellent laser sensitivity and exhibits high ink repellency equivalent to or higher than that of a conventional PS plate.

[Brief description of the drawings]

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

Claims (4)

[Claims] 1. A lithographic printing plate precursor comprising at least a laser-sensitive hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer is sensitive to actinic rays by laser irradiation and causes destructive absorption. Laser-sensitive lithographic printing plate precursor. 2. A lithographic printing plate precursor comprising at least a laser-sensitive hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer contains a black pigment or a black dye. Printing plate original. 3. 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. The described laser-sensitive lithographic printing plate precursor. 4. The lithographic printing plate precursor as claimed in claim 2, further comprising a primer layer between the substrate and the hydrophilic swelling layer.