JP2002067525A - Original plate for thermosensitive lithographic printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original plate for thermosensitive lithographic printing having good on-press developability, high plate wear resistance, a difficulty in a contamination of printing and excellent ink repellency in the plate capable of printing by mounting the plate in a printer as it is after scanning exposure based on a digital signal. SOLUTION: The original plate for thermosensitive lithographic printing comprises a thermosensitive layer containing hydrophobic thermoplastic fine particles and a hydrophilic binder polymer to be melted by a heat on an aluminum support having an anodized film. In the original plate, micropores of the anodized film are treated to be enlarged. The plate also comprises an undercoating layer provided on a surface of the anodized layer and containing a water soluble resin having a carboxyl group or a carboxylate group, and a water soluble salt of at least one type of metal selected from the group consisting of zinc, calcium, magnesium, barium, strontium, cobalt, manganese and nickel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive lithographic printing plate for a computer-to-plate system which does not require development. More specifically, it is possible to record an image by infrared scanning exposure based on a digital signal, and the recorded image can be directly attached to a printing machine and printed without going through a conventional developing process using a liquid. It relates to a possible heat-sensitive lithographic printing plate.

[0002]

2. Description of the Related Art Numerous studies have been made on lithographic printing original plates for computer-to-plate systems, which have made remarkable progress in recent years. Among them, after exposure, we aim to further streamline the process and solve the waste liquid treatment problem.
A lithographic printing plate that can be directly mounted on a printing machine for printing has been studied, and various methods have been proposed. One promising method is a heat-sensitive lithographic printing original plate, in which a hydrophilic layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder polymer is used as an image forming heat-sensitive layer. This method utilizes the fact that when heat is applied to the heat-sensitive layer, the hydrophobic thermoplastic polymer particles are fused and the surface of the hydrophilic heat-sensitive layer is converted into an oleophilic image area.

[0003] Among the methods utilizing heat fusion of the hydrophobic thermoplastic polymer particles, one of the methods for eliminating the processing step is to mount an exposed printing master on a cylinder of a printing press and rotate the cylinder. There is a method called on-press development in which a non-image portion of a printing original plate is removed by supplying a dampening solution and ink while the ink is being supplied. That is, the printing master is mounted on a printing machine as it is after exposure, and the process is completed in a normal printing process. A lithographic printing plate suitable for such on-press development has a photosensitive layer soluble in fountain solution and ink solvent, and is suitable for development on a printing machine placed in a bright room. It is required to have a light room handling property.

For example, Japanese Patent No. 2938397 discloses an original plate for lithographic printing wherein a photosensitive layer in which fine particles of a thermoplastic hydrophobic polymer are dispersed in a hydrophilic binder polymer is provided on a hydrophilic support. I have. According to this publication, the plate for lithographic printing is subjected to infrared laser exposure to form an image by heat-bonding fine particles of a thermoplastic hydrophobic polymer to form an image. Then, the plate is mounted on a printing press cylinder, and dampening water and / or Alternatively, it is described that on-press development can be performed by supplying ink. Further, since the lithographic printing plate has a photosensitive region in an infrared region, it is also suitable for handling in a bright room.

Further, Japanese Patent Application Laid-Open Nos. 9-127683 and WO99-10186 also disclose that a printing plate is prepared by on-press development after combining thermoplastic fine particles by heat.

[0006] However, such a method of forming an image by combining fine particles by heat shows good on-press developability, but the adhesion between the aluminum support and the image is weak, and the image strength is also low. There was a problem that the printing durability was insufficient. As a countermeasure, it is known to use a phosphoric acid bath anodic oxide film having a strong adhesive force, but this method has a drawback that the ink wiping property is deteriorated.

Further, Japanese Patent Application Laid-Open No. 8-48020 discloses that
A method is described in which a lipophilic thermosensitive layer is provided on a porous hydrophilic support, exposed to infrared laser, and the lipophilic thermosensitive layer is fixed to a substrate by heat. However, a lipophilic film has poor on-press developability, and there is a problem that scum of the lipophilic thermosensitive layer adheres to an ink roller or printed matter.

[0008]

It is an object of the present invention to provide a heat-sensitive lithographic printing plate which overcomes the disadvantages of the prior art as described above. That is, it is an object of the present invention to provide a heat-sensitive lithographic printing plate which has good on-press developability, has high printing durability, and is excellent in difficulty in soiling such as background stain and ink dispensing property in printing. .

[0009]

Means for Solving the Problems As a result of diligent studies, the present inventors have found that the above object can be achieved by subjecting a highly adhesive support to a hydrophilic surface treatment. That is, the present invention is as follows.

[0010] 1. A heat-sensitive lithographic printing plate having a heat-sensitive layer containing hydrophobic thermoplastic fine particles and a hydrophilic binder polymer melted by heat on an aluminum support having an anodized film, wherein the micropores of the anodized film are Pore wide treatment, and on the surface thereof, a water-soluble resin having a carboxyl group or a carboxylate group,
A heat-sensitive lithographic printing plate having an undercoat layer containing a water-soluble salt of at least one metal selected from zinc, calcium, magnesium, barium, strontium, cobalt, manganese and nickel.

2. The heat-sensitive lithographic printing original plate as described in 1 above is image-exposed with a laser beam and is attached to a printing machine for printing, or after being attached to the printing machine, is exposed to the laser beam on a printing machine and printed as it is. A method for making and printing a heat-sensitive lithographic printing plate, comprising:

[0012]

Embodiments of the present invention will be described below in detail. The aluminum support used in the present invention is a dimensionally stable metal containing aluminum as a main component, and is made of aluminum or an aluminum alloy. In addition to a pure aluminum plate, it is selected from an alloy plate containing aluminum as a main component and containing a trace amount of a different element, or a plastic film or paper on which aluminum (alloy) is laminated or evaporated. Further,
A composite sheet in which an aluminum sheet is bonded to a polyethylene terephthalate film as described in JP 18327 may be used.

In the following description, the above-mentioned supports made of aluminum or an aluminum alloy are collectively used as aluminum supports. The foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel and titanium, and the content of the foreign elements in the alloy is 10% by weight or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to produce due to refining technology, and therefore may contain a slightly different element. Thus, the aluminum plate applied to the present invention, the composition is not specified, conventionally known and publicly available materials, such as JIS A 1050, JIS A 1100, JIS A 3103,
JIS A 3005 can be used as appropriate. The thickness of the aluminum support used in the present invention is about 0.1 to 0.6 mm. This thickness can be appropriately changed according to the size of the printing press, the size of the printing plate, and the user's request. The aluminum support is appropriately subjected to a support surface treatment described below.

The surface of the aluminum support used in the present invention can be grained. Examples of the graining method include mechanical graining, chemical etching, and electrolytic grain as described in JP-A-56-28893. Furthermore, an electrochemical graining method in which the aluminum surface is electrochemically grained in a hydrochloric acid or nitric acid electrolyte, a wire brush graining method in which the aluminum surface is scratched with a metal wire, and a ball graining method in which the aluminum surface is grained with a polishing ball and an abrasive. A mechanical graining method such as a brush graining method in which the surface is grained with a nylon brush and an abrasive can be used, and these graining methods can be used alone or in combination. Among them, a method for producing a surface roughness usefully used in the present invention is an electrochemical method of chemically graining in a hydrochloric acid or nitric acid electrolyte, and a preferable current density is 100 to 400 C / d.
m ² . More specifically, in an electrolyte containing 0.1 to 50% by weight of hydrochloric acid or nitric acid, the temperature is 20 to 10%.
0 ° C., time 1 second to 30 minutes, current density 100 to 400 C /
It is preferable to perform electrolysis under the condition of dm ² . It is also preferable to perform the combination of mechanical graining and electrochemical graining.

The grained aluminum support is chemically etched with an acid or an alkali. When an acid is used as an etching agent, it takes time to destroy a fine structure, which is disadvantageous when applied to the present invention industrially. However, it can be improved by using an alkali as an etching agent. Alkali agents suitably used in the present invention are sodium hydroxide, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, and the like. ~ 50% by weight, 20 ~
100 ° C., and the amount of aluminum dissolved is 5 to 20 g /
It is preferable that the condition be m ² . After the etching, pickling is performed to remove dirt (smut) remaining on the surface. As the acid used, nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, borofluoric acid and the like are used. In particular, as a method for removing the smut after the electrochemical surface-roughening treatment, it is preferable to use 15 to 65% by weight of a temperature of 50 to 90 ° C. as described in JP-A-53-12739.
And an alkali etching method described in JP-B-48-28123.

The aluminum support thus treated is further subjected to an anodic oxidation treatment. The anodizing treatment can be performed by a method conventionally performed in this field. Specifically, by flowing a direct current or an alternating current to an aluminum support in an aqueous solution or a non-aqueous solution containing at least one selected from sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, and the like, aluminum An anodized film can be formed on the surface of the support. The conditions of the anodizing treatment vary depending on the electrolytic solution to be used, and thus cannot be unconditionally determined. The range of 5 to 60 A / dm ² , the voltage of 1 to 100 V, and the electrolysis time of 10 to 100 seconds is preferable. Among these anodizing treatments, in particular, British Patent No. 1,412,76
No. 8, a method of anodizing with high current density in sulfuric acid and a method of anodizing phosphoric acid as an electrolytic bath described in US Pat. No. 3,511,661 are preferred. In the present invention, the anodic oxide film is 1 to
It is preferably 10 g / m ² , more preferably
1.5 to 7 g / m ² . More preferably, 2 to 5 g
/ M ² . The above-mentioned anodic oxide film has fine concave portions called micropores formed uniformly on its surface. The density of the micropores present in the anodic oxide film can be adjusted by appropriately selecting the processing conditions.

One of the features of the present invention is that after the anodizing treatment, the micropore is treated with an acid or alkali aqueous solution (pore widening treatment) in order to increase the pore diameter. This treatment is a treatment in which the aluminum substrate on which the anodized film is formed is immersed in an acid or alkali aqueous solution to dissolve the anodized film, and as a result, the pore diameter of the micropore is enlarged. This pore widening treatment is preferably performed in an amount of 0.05 to 20 g / m
² , more preferably 0.1 to 5 g / m ² , particularly preferably 0.2 to 4 g / m ² .

As the conditions for the pore widening treatment for dissolving the anodic oxide film, the following condition ranges are desirable. Within this range, good pore wide processing can be performed. As a specific condition range, when treating with an aqueous acid solution, it is preferable to use an aqueous solution of an inorganic acid such as sulfuric acid or phosphoric acid or a mixture thereof, and the concentration is preferably 10 to 500 g.
/ L, more preferably 20 to 100 g / l, and the temperature is preferably 10 to 90 ° C, more preferably 40 to 7 ° C.
0 ° C., the immersion time is preferably 10 to 300
Seconds, more preferably 30 to 120 seconds. On the other hand, when treating with an alkaline aqueous solution, it is preferable to use at least one aqueous solution selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide, and the pH of the aqueous solution is preferably 11 to 13, The temperature is more preferably 11.5 to 12.5, and the temperature is preferably 10 to 90 ° C, more preferably 30 to 50 ° C, and the immersion time is preferably 5 to 300 seconds, more preferably 10 to 90 ° C. 30 seconds.

In the present invention, after the pore widening treatment, if necessary, a hydrophilic surface treatment by immersion in an aqueous solution containing a hydrophilic compound may be performed. Suitable hydrophilic compounds include polyvinyl phosphonic acid, compounds having a sulfonic acid group, and saccharide compounds.

The compounds having a sulfonic acid group include aromatic sulfonic acids, formaldehyde condensates thereof, derivatives and salts thereof. As the aromatic sulfonic acid, phenolsulfonic acid, catecholsulfonic acid, resorcinolsulfonic acid, benzenesulfonic acid, toluenesulfonic acid, ligninsulfonic acid, naphthalenesulfonic acid, acenaphthene-5-sulfonic acid, phenanthrene-2-sulfonic acid, Benzaldehyde-2 (or 3)
Sulfonic acid, benzaldehyde-2,4 (or 3,
5) -Disulfonic acid, oxybenzylsulfonic acids, sulfobenzoic acid, sulfanilic acid, naphthonic acid, taurine and the like are used. Among these, benzenesulfonic acid, naphthalenesulfonic acid, ligninsulfonic acid and their formaldehyde condensates are particularly preferred. Further, it may be used as a sulfonate, and examples thereof include a sodium salt, a potassium salt, a lithium salt, a calcium salt, and a magnesium salt. Among them, aqueous solutions of sodium salts and potassium salts are particularly desirable. The pH of the aqueous solution containing the above compound is preferably 4-6.5, and can be adjusted to this pH range with sulfuric acid, sodium hydroxide, ammonia or the like.

The saccharide compounds include monosaccharides and their sugar alcohols, oligosaccharides, polysaccharides and glycosides. Monosaccharides include trioses and sugar alcohols such as glycerol, tetroses and sugar alcohols such as threose and erythritol, pentoses and sugar alcohols such as arabinose and arabitol, hexoses and sugar alcohols such as glucose and sorbitol, and D-glycero. -Heptose and sugar alcohols such as -D-galactoheptose and D-glycero-D-galactoheptitol, octose such as D-erythro-D-galactooctitol, and nonose such as D-erythro-L-gluco-nonulose. Can be mentioned. Oligosaccharides include disaccharides such as saccharose, trehalose and lactose, and trisaccharides such as raffinose. Examples of the polysaccharide include amylose, arabinan, cyclodextrin, cellulose alginate and the like.

The glycoside is a compound in which a sugar moiety and a non-sugar moiety are linked via an ether bond or the like. These glycosides can be classified according to non-sugar moieties, such as alkyl glycosides, phenolic glycosides, coumarin glycosides, oxycoumarin glycosides, flavonoid glycosides, anthraquinone glycosides, Examples include triterpene glycosides, steroid glycosides, mustard oil glycosides, and the like. Examples of the sugar moiety include monosaccharides, oligosaccharides, and polysaccharides. As monosaccharides, trioses and sugar alcohols such as glycerol, tetroses and sugar alcohols such as threose and erythritol, pentoses and sugar alcohols such as arabinose and arabitol, hexoses and sugar alcohols such as glucose and sorbitol, D-
Glycero-D-galactoheptose and D-glycero-D
-Heptose and sugar alcohols such as -galactoheptitol, octose such as D-erythro-D-galactooctitol, and nonose such as D-erythro-L-gluco-nonulose. As oligosaccharides,
Examples include disaccharides such as saccharose, trehalose and lactose, and trisaccharides such as raffinose. Examples of the polysaccharide include amylose, arabinan, cyclodextrin, cellulose alginate and the like. The sugar moiety is preferably a monosaccharide or an oligosaccharide, and more preferably a monosaccharide or a disaccharide. Examples of preferred glycosides include compounds of the following general formula (I).

[0023]

Embedded image

(In the formula (I), R represents a linear or branched alkyl group, alkenyl group or alkynyl group having 1 to 20 carbon atoms.)

Examples of the alkyl group having 1 to 20 carbon atoms represented by R in the general formula (I) include methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, Examples include undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl groups. These alkyl groups may be linear or branched, or may be cyclic alkyl groups. Examples of the alkenyl group include an allyl and a 2-butenyl group, and examples of the alkynyl group include a 1-pentynyl group.

Specific compounds represented by the above general formula (I) include, for example, methyl glucoside, ethyl glucoside, propyl glucoside, isopropyl glucoside, butyl glucoside, isobutyl glucoside, n-hexyl glucoside, octyl glucoside, caprylic glucoside, decyl Examples include glucoside, 2-ethylhexyl glucoside, 2-pentyl nonyl glucoside, 2-hexyl decyl glucoside, lauryl glucoside, myristyl glucoside, stearyl glucoside, cyclohexyl glucoside, and 2-butynyl glucoside. These compounds are glucosides, which are a kind of glycosides, in which the hemiacetal hydroxyl group of glucose is linked to another compound in an ether state, and can be obtained, for example, by a known method of reacting glucose with alcohols. . Some of these alkyl glucosides are marketed under the trade name GLUCOPON by Henkel, Germany, and can be used in the present invention. Other examples of preferred glycosides include saponins, rutin trihydrate, hesperidin methyl chalcone, hesperidin, narizine hydrate, phenol-β-D-glucopyranoside, salicin, 3 ′, 5,7-methoxy-7.
-Rutinoside.

The pH of the aqueous solution containing the above compound can be adjusted with potassium hydroxide, sulfuric acid, carbonic acid, sodium carbonate, phosphoric acid, and sodium phosphate.
11 is preferred.

The aqueous solution of polyvinyl phosphonic acid has a concentration of 0.
It is preferably from 1 to 5% by weight, more preferably from 0.2 to 2.5%. The immersion temperature is preferably from 10 to 70 ° C, and from 30 to 60 ° C.
C is more preferred. The immersion time is preferably from 1 to 20 seconds.
The aqueous solution of the compound having a sulfonic acid group has a concentration of 0.1.
Preferably, the immersion temperature is 60 to 10%.
0 ° C. is preferred. Immersion time is preferably 1 to 300 seconds,
More preferably, it is 10 to 100 seconds. Further, the concentration of the aqueous solution of the saccharide is preferably 0.5 to 10% by weight, and the immersion temperature is preferably 40 to 70 ° C. The immersion time is preferably from 2 to 300 seconds, more preferably from 5 to 30 seconds.

As the aqueous solution containing the hydrophilic compound, not only the treatment with the aqueous solution of the organic compound as described above, but also an aqueous solution of an alkali metal silicate, an aqueous solution of potassium zirconium fluoride (K ₂ ZrF ₆ ) or a phosphate Treatment with an aqueous solution of an inorganic compound such as an aqueous solution containing an inorganic fluorine compound is also suitable. The alkali metal silicate aqueous solution treatment
The concentration of the alkali metal silicate is preferably 1 to 30% by weight, more preferably 2 to 15% by weight, and an aqueous solution having a pH of 10 to 13 at 25 ° C, preferably 50 to 9%.
Immerse at 0 ° C. for 0.5 to 40 seconds, more preferably 1 to 20 seconds.

As the alkali metal silicate used in the present invention, sodium silicate, potassium silicate, lithium silicate and the like are used, and among them, sodium silicate and potassium silicate are preferable. PH of alkali metal silicate aqueous solution
Examples of the hydroxide used to increase the value include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like, and preferably, sodium hydroxide and potassium hydroxide are used. In addition, an alkaline earth metal salt or a Group IVB metal salt may be added to the above treatment liquid. Examples of the alkaline earth metal salts include nitrates such as calcium nitrate, strontium nitrate, magnesium nitrate, and barium nitrate, and water-soluble salts such as sulfates, hydrochlorides, phosphates, acetates, oxalates, borates, and the like. Is mentioned. Group IVB metal salts include titanium tetrachloride, titanium trichloride, potassium titanium fluoride, potassium potassium oxalate, titanium sulfate, titanium tetraiodide,
Examples thereof include zirconium chloride oxide, zirconium dioxide, zirconium oxychloride, and zirconium tetrachloride. The alkaline earth metal or Group IVB metal salt can be used alone or in combination of two or more. The concentration of the aqueous solution of potassium zirconium fluoride is 0.1 to 1
0% by weight is preferable, and 0.5 to 2% by weight is more preferable. The immersion temperature is preferably from 30 to 80C. Immersion time is 6
0 to 180 seconds is preferred.

The phosphate / inorganic fluorine compound treatment was carried out by treating the phosphate compound with 5 to 20% by weight and the inorganic fluorine compound with 0.01%.
It is preferable to use an aqueous solution having a pH of 3 to 1% by weight.
Adjust to 5. The immersion temperature is preferably 30 to 90 ° C., and the immersion time is preferably 2 to 300 seconds, more preferably 5 to 90 seconds.
30 seconds.

Examples of the phosphate include phosphates of metals such as alkali metals and alkaline earth metals. Specifically, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, potassium dihydrogen phosphate, Dipotassium hydrogen phosphate, calcium phosphate, ammonium sodium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, disodium hydrogen phosphate , Lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid,
Examples include ammonium phosphotungstate, sodium phosphotungstate, ammonium phosphomolybdate, and sodium phosphomolybdate. Further, sodium phosphite, sodium tripolyphosphate and sodium pyrophosphate can be mentioned. Preferably, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate can be used.

As the inorganic fluorine compound, a metal fluoride is preferred. Specifically, sodium fluoride, potassium fluoride, calcium fluoride, magnesium fluoride, sodium hexafluorozirconium, potassium hexafluorozirconium, sodium hexafluorotitanate, potassium hexafluorotitanate, hexafluorozirconium hydrochloride, hexafluorozirconium Examples include hydrofluorotitanic acid, ammonium hexafluorozirconium, ammonium hexafluorotitanate, hexafluorosilicic acid, nickel fluoride, iron fluoride, phosphoric acid phosphoric acid, and ammonium fluoride phosphate. In the present invention, the aqueous solution may contain one or more of the phosphate and the inorganic fluorine compound. After the immersion treatment in these aqueous solutions, all the substrates are washed with water or the like and dried.

In the present invention, the water-soluble resin having a carboxylic acid group or a carboxylate group and a water-soluble resin of at least one metal selected from zinc, calcium, magnesium, barium, strontium, cobalt, manganese and nickel after the pore widening treatment. Another feature is that it has an undercoat layer containing a neutral salt.

Examples of the water-soluble resin having a carboxyl group or a carboxylate group suitable for the present invention include polyacrylic acid, sodium alginate, carboxylic acid-modified starch, and water-soluble salts of carboxyalkyl cellulose. Examples of the water-soluble salt of carboxyalkylcellulose include carboxymethylcellulose, carboxyethylcellulose and carboxypropylcellulose, and potassium or sodium salts are preferred. Still other suitable water-soluble resins having a carboxyl group or a carboxylate group include copolymers of acrylamide and (meth) acrylic acid, copolymers of vinylpyrrolidone and (meth) acrylic acid, and vinyl acetate and maleic anhydride. Examples include a hydrolyzate of a copolymer, a copolymer of a monomer having a carboxyl group such as a copolymer of hydroxyalkyl (meth) acrylate and (meth) acrylic acid, or a water-soluble salt such as a sodium salt or a potassium salt thereof. Can be.

The water-soluble salt of a metal used in the undercoat layer of the present invention includes zinc, calcium, magnesium, barium, strontium and organic or inorganic acid.
There is a water-soluble salt of a metal selected from cobalt, manganese and nickel. Representative organic acid salts are salicylic acid,
Mention may be made of salts of carboxylic acids such as benzoic acid, acetic acid, propionic acid, butyric acid and fumaric acid, and acetylacetonate. Representative inorganic acid salts are bromate, bromide, chlorate, chloride, dithionate, iodide, nitrate and sulfate.

The undercoat layer contains a water-soluble resin having a carboxyl group or a carboxylate group and the above-mentioned metal water-soluble salt, and may be provided by applying a mixed solution of both, or And then a solution of a water-soluble metal salt may be applied thereon, or may be applied separately in the reverse order. A suitable undercoat layer coating composition (undercoat liquid) can be produced as an aqueous solution. To this, an organic solvent such as alcohol or ketone can be added as needed. The solid content concentration of the undercoat liquid is 0.15 to 0.75% by weight [water-soluble resin is about 0.1%.
To about 0.5% by weight and the water-soluble salt of the metal is about 0.05 to about 0.25% by weight], and more preferably the solid concentration is 0.2 to 0.6% by weight. The dry coating weight of the undercoat layer is preferably from 1 to 100 mg / m ² ,
mg / m ² is more preferred. Within this range, good ink-wiping properties and adhesion to the heat-sensitive layer can be obtained.

By this hydrophilic undercoat, problems of printing stains such as deterioration of ink dispensing property which occur in exchange for the adhesiveness improved by the pore widening treatment after the anodic oxidation treatment are solved. In other words, generally, when the pore diameter is enlarged, a phenomenon that it is difficult to remove ink (deterioration of ink dispensing property) occurs at the time of printing, particularly when the printing press is stopped and printing is restarted after the printing plate has been left on the printing press. However, when the undercoat is applied, the hydrophilicity of the surface is improved, so that the problem of deterioration of ink dispensing property is reduced.

The heat-sensitive layer of the present invention contains fine particles of a hydrophobic thermoplastic polymer melted by heat and a hydrophilic binder polymer.

The hydrophobic thermoplastic polymer particles used in the heat-sensitive layer of the present invention preferably have a solidification temperature of 35 ° C. or more, and more preferably 50 ° C. or more. Although there is no particular upper limit on the solidification temperature of the thermoplastic hydrophobic polymer fine particles used in the present invention, this temperature must be sufficiently lower than the decomposition point of the polymer fine particles. When the polymer particulates are raised above the coagulation temperature, they fuse and coalesce to form hydrophobic agglomerates in the thermosensitive layer. Therefore, these portions become insoluble in water or an aqueous liquid and become ink-receptive.

As specific examples of the hydrophobic polymer constituting the hydrophobic fine particles used in the heat-sensitive layer of the present invention, for example, ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, Mention may be made of homopolymers or copolymers from monomers such as vinylidene chloride, acrylonitrile, vinylcarbazole or mixtures thereof.
Among them, polystyrene and polymethyl methacrylate are particularly preferable.

[0042] The weight average molecular weight of the hydrophobic polymer used in the heat-sensitive layer of the present invention may be in the range of 5,000 to 1,000,000.

The hydrophobic fine particles of the present invention have a particle size of 0.01 to 50 μm.
m, more preferably from 0.05 to 10 μm, and most preferably from 0.05 to 2 μm.

The amount of the hydrophobic thermoplastic polymer fine particles contained in the heat-sensitive layer is preferably from 20 to 65% of the solid content of the heat-sensitive layer.
% By weight, and more preferably between 25 and 55% by weight, and most preferably between 30 and 45% by weight.

Examples of the hydrophilic binder polymer include a hydroxyl group, a hydroxyethyl group, a hydroxypropyl group, an amino group, an aminoethyl group, an aminopropyl group, an amide group, a carboxyl group, a carboxymethyl group,
Those having a hydrophilic group such as a carboxylate group are preferred.

Specific examples of the hydrophilic binder polymer include gum arabic, casein, gelatin, starch derivatives,
Carboxymethylcellulose and its sodium salt,
Cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, hydroxyethyl acrylate Homopolymers and copolymers, hydroxypropyl methacrylate homopolymers and copolymers, hydroxypropyl acrylate homopolymers and copolymers, hydroxybutyl methacrylate homopolymers and copolymers, hydroxybutyl acrylate homopolymers and copolymers, polyethylene glycols, hydroxypropylene polymers, Polyvinyl alcohols, and the degree of hydrolysis is at least 0 wt%, preferably at least 8
0% by weight of hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, homopolymers and copolymers of acrylamide, homopolymers and polymers of methacrylamide,
Examples thereof include homopolymers and copolymers of N-methylolacrylamide.

The amount of the hydrophilic binder polymer to be added to the heat-sensitive layer is preferably 5 to 40% by weight based on the solid content of the heat-sensitive layer.
0-30% by weight is more preferred. Within this range, good on-press developability and film strength can be obtained.

The heat-sensitive layer of the present invention may contain a photothermal conversion agent that absorbs infrared rays and generates heat to improve sensitivity. As such a photothermal conversion agent, 700 to 12
Any light absorbing substance having an absorption band in at least a part of 00 nm may be used, and various pigments, dyes and metal fine particles can be used.

Examples of the type of the pigment include a black pigment, a brown pigment, a red pigment, a violet pigment, a blue pigment, a green pigment, a fluorescent pigment, a metal powder pigment, and a polymer-bound pigment. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelated azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments And quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like.

These pigments may be used without surface treatment, or may be used after surface treatment. Examples of the surface treatment include a method of surface-coating a hydrophilic resin or a lipophilic resin, a method of attaching a surfactant, and a reactive substance (eg, silica sol, alumina sol, a silane coupling agent, an epoxy compound, an isocyanate compound, and the like). Can be conceived on the surface of the pigment. The above surface treatment methods are described in "Properties and Applications of Metallic Soap" (Koshobo), "Printing Ink Technology"
(CMC Publishing, 1984) and "Latest Pigment Application Technology" (CMC Publishing, 1986).
Among these pigments, those that absorb infrared rays are preferred because they are suitable for use in lasers that emit infrared rays. As such a pigment absorbing infrared rays, carbon black is preferable. The particle size of the pigment is preferably in the range of 0.01 μm to 1 μm, and more preferably in the range of 0.01 μm to 0.5 μm.

Examples of the dye include commercially available dyes and literatures (for example, “Near-Infrared Absorbing Dyes” in “Chemical Industry”, May 1986, p. , "Development and Market Trend of 90s Functional Dyes", Chapter 2, Section 2.3 (1990), CM) or patents can be used. Specifically, infrared absorbing dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, polymethine dyes, and cyanine dyes are preferred.

Further, for example, Japanese Patent Application Laid-Open No. 58-12524
No. 6, JP-A-59-84356, JP-A-60-787
No. 87, etc .;
173696, JP-A-58-181690, methine dyes described in JP-A-58-194595, and the like;
JP-A-58-112793, JP-A-58-22479
No. 3, JP-A-59-48187, JP-A-59-739
No. 96, JP-A-60-52940, JP-A-60-63
744, etc .; squarylium dyes described in JP-A-58-112792, etc .; cyanine dyes described in British Patent 434,875; and dyes described in U.S. Pat. No. 4,756,993. And cyanine dyes described in U.S. Pat. No. 4,973,572, dyes described in JP-A-10-268512, JP-A-11-235.
No. 883.

As a dye, US Pat. No. 5,156,
No. 938 is also preferably used, and substituted arylbenzo (thio) pyrylium salts described in U.S. Pat. No. 3,881,924;
No. 42645, JP-A-58-181051, JP-A-58-220143, JP-A-59-41363, JP-A-59-84248, and JP-A-59-84248.
No. 84249, No. 59-146063, No. 59-14
No. 6061, pyranium compounds described in JP-A-59-216146, cyanine dyes described in US Pat. No. 4,283,475, pentamethine thiopyrylium salts described in U.S. Pat. 5-70
No. 2, a pyrylium compound, Epolite III-178, Epolite III-130, manufactured by Eporin Co., Ltd.
Epolite III-125 and the like are also preferably used. Among these, a dye suitable for being added to a hydrophilic matrix such as a hydrophilic resin of a heat-sensitive layer is a water-soluble dye, and some specific examples are shown below.

[0054]

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[0055]

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As the infrared absorbing dye to be added to the hydrophobic thermoplastic fine particles of the heat-sensitive layer of the present invention, the above-mentioned infrared absorbing dye may be used, but a lipophilic dye is more preferable.
Specific examples include the following dyes.

[0057]

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[0058]

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The above-mentioned organic photothermal conversion agent can be added up to 30% by weight in the thermosensitive layer. Preferably 5
The content is 25% by weight, particularly preferably 7 to 20% by weight. Within this range, good sensitivity is obtained.

In the heat-sensitive layer of the present invention, fine metal particles can also be used as a photothermal conversion agent. Most of the metal fine particles are light-heat converting and self-heating, but preferred metal fine particles include Si, Al, Ti, V, Cr, and M.
n, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo,
Ag, Au, Pt, Pd, Rh, In, Sn, W, T
e, Pb, Ge, Re, and Sb alone or as an alloy, or fine particles of oxides or sulfides thereof. Among the metals constituting these metal fine particles, preferred metals are those which are liable to be coalesced by heat at the time of light irradiation, and have a melting point of about 1000 ° C. or less and have absorption in the infrared, visible or ultraviolet region, for example, Re, Sb, Te, Au, A
g, Cu, Ge, Pb and Sn. Particularly preferred are metal fine particles having a relatively low melting point and a relatively high absorbance to infrared rays, for example, Ag, Au, C
Among u, Sb, Ge and Pb, the most preferred elements include Ag, Au and Cu.

Further, for example, Re, Sb, Te, Au, A
g, Cu, Ge, Pb, Sn and other low melting point metal particles and self-heating metal particles such as Ti, Cr, Fe, Co, Ni, W and Ge. It may be made of a light-to-heat conversion material. Also, Ag,
It is also preferable to use a combination of a metal-type micro-piece and a metal-type micro-piece having a particularly large light absorption when made into a micro-piece such as Pt or Pd.

The size of these particles is preferably 10 μm.
m, more preferably 0.003 to 5 μm, particularly preferably 0.01 to 3 μm. Within this range, good sensitivity and resolution can be obtained.

In the present invention, when these metal fine particles are used as a light-to-heat converting agent, the amount added is preferably at least 10% by weight, more preferably at least 20% by weight, particularly preferably at least 30% by weight of the solid content of the heat-sensitive layer. Used in weight percent or more. High sensitivity is obtained within this range.

The photothermal conversion agent may contain an undercoat layer adjacent to the heat-sensitive layer or a water-soluble overcoat layer described later. When at least one of the heat-sensitive layer, the undercoat layer, and the overcoat layer contains a light-to-heat conversion agent, infrared absorption efficiency is increased and sensitivity can be improved.

The heat-sensitive layer of the present invention may contain a crosslinking agent, if necessary. Suitable crosslinking agents include low molecular weight compounds having a methylol group, such as melamine-formaldehyde resin, hydantoin-formaldehyde resin, thiourea-formaldehyde resin, and benzoguanamine-formaldehyde resin.

The heat-sensitive layer of the present invention may further contain various compounds other than those described above, if necessary. For example, a dye having a large absorption in the visible light region can be used as a colorant for an image in order to make it easy to distinguish between an image portion and a non-image portion after image formation. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink #
312, oil green BG, oil blue BOS, oil blue # 603, oil black BY, oil black BS, oil black T-505 (all manufactured by Orient Chemical Co., Ltd.), Victoria Pure Blue, crystal violet (CI42555), methyl Violet (CI42535), ethyl violet, rhodamine B (CI145170B), malachite green (CI42000), methylene blue (CI5201)
5) etc. and dyes described in JP-A-62-293247. Also, pigments such as phthalocyanine pigments, azo pigments, and titanium oxide can be suitably used. The addition amount is preferably 0.01 to 10% by weight based on the total solid content of the heat-sensitive layer coating solution.

Furthermore, a plasticizer can be added to the heat-sensitive layer of the present invention, if necessary, to impart flexibility to the coating film. For example, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate,
Dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, and the like are used.

The heat-sensitive layer of the present invention is prepared by dissolving the above-mentioned necessary components in a solvent to prepare a coating solution. As the solvent used here, ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Ethane, methyl lactate, ethyl lactate,
N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethylsulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like, but are not limited thereto. is not. These solvents are used alone or as a mixture. The solid content concentration of the coating solution is preferably 1 to 50% by weight.

The coating amount (solid content) of the heat-sensitive layer on the support obtained after coating and drying varies depending on the use, but is generally preferably 0.5 to 5.0 g / m ² . When the amount of coating is smaller than this range, the apparent sensitivity increases, but the film characteristics of the heat-sensitive layer that performs the function of image recording deteriorate. Various methods can be used as a method of applying. For example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating,
Examples include blade coating and roll coating.

A surfactant for improving coating properties, for example, a fluorine-based surfactant as described in JP-A-62-170950 can be added to the coating solution for the heat-sensitive layer. A preferable addition amount is 0.1% of the total solid content of the heat-sensitive layer.
The content is from 01 to 1% by weight, more preferably from 0.05 to 0.5% by weight.

In the lithographic printing plate precursor of the present invention, a water-soluble overcoat layer can be provided on the heat-sensitive layer in order to prevent the surface of the heat-sensitive layer from being stained with a lipophilic substance. The water-soluble overcoat layer used in the present invention can be easily removed at the time of printing and contains a resin selected from water-soluble organic polymer compounds. As the water-soluble organic polymer compound used here, a film formed by coating and drying has a film-forming ability, specifically, polyvinyl acetate (having a hydrolysis rate of 65% or more), polyacrylic Acid, alkali metal salt or amine salt thereof, polyacrylic acid copolymer, alkali metal salt or amine salt thereof, polymethacrylic acid, alkali metal salt or amine salt thereof, polymethacrylic acid copolymer, alkali metal salt thereof or amine Salt, polyacrylamide, its copolymer, polyhydroxyethyl acrylate, polyvinylpyrrolidone,
The copolymer, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, alkali metal salt or amine salt thereof, poly-2-acrylamide- 2-methyl-1-propanesulfonic acid copolymer, an alkali metal salt or an amine salt thereof, gum arabic, a cellulose derivative (eg, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.), a modified product thereof, white dextrin, Pullulan,
Examples include enzymatically degraded etherified dextrins. Further, according to the purpose, two or more of these resins can be used in combination.

The above-mentioned water-soluble photothermal conversion agent may be added to the overcoat layer. Furthermore, in the case of aqueous solution application, a nonionic surfactant such as polyoxyethylene nonylphenyl ether and polyoxyethylene dodecyl ether can be added to the overcoat layer in order to ensure uniformity of application. . Dry coating amount of the overcoat layer, 0.1 to 2.0 g / m ² is preferred. Within this range, the surface of the heat-sensitive layer can be favorably prevented from being stained by a lipophilic substance such as a fingerprint stain without impairing the on-press developability.

The lithographic printing plate of the present invention forms an image by heat. Specifically, direct image-like recording using a thermal recording head or the like, scanning exposure using an infrared laser, high-intensity flash exposure such as a xenon discharge lamp, or infrared lamp exposure is used. Semiconductors that emit infrared light having a wavelength of 700 to 1200 nm are used. Exposure with a solid-state high-output infrared laser such as a laser or a YAG laser is preferable.

The lithographic printing plate precursor of the present invention, which has been image-exposed, can be mounted on a printing press without any further processing, and can be printed by an ordinary procedure using ink and fountain solution. These lithographic printing original plates are disclosed in Japanese Patent No. 293839.
As described in No. 8, after being mounted on a printing press cylinder, it can be exposed by a laser mounted on the printing press, and then developed with a dampening solution and / or ink. is there. These lithographic printing original plates can be used for printing after development using water or an appropriate aqueous solution as a developing solution.

[0075]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

[Example of Production of Support] An aluminum plate having a thickness of 0.3 mm and a material of JIS A 1050 was grained with a No. 8 nylon brush and an aqueous suspension of 800 mesh pamiston, and the surface thereof was grained. Washed with water. This plate was immersed in a 10% aqueous solution of sodium hydroxide at 70 ° C. for 60 seconds for etching, washed with running water, and further washed with
It was neutralized and washed with 0% nitric acid and then washed with water. This is Va =
Under the condition of 12.7 V, 1
The electrolytic surface roughening treatment was performed in a 300% aqueous solution of nitric acid at an anode charge of 300 C / dm ² . When the surface roughness of the aluminum plate was measured, it was 0.45 μm (Ra display). Subsequently, after immersing in a 30% sulfuric acid aqueous solution and desmutting at 55 ° C. for 2 minutes, 5 A / dm in 15% sulfuric acid at 33 ° C.
DC electrolysis was performed at a current density of ² for 45 seconds to form an anodic oxide film. (This support is referred to as support (0).)
In order to enlarge the micropores of the anodic oxide film formed on the support (0), the support was immersed in 50 g / l sulfuric acid at 60 ° C. for 1 minute, washed with water and dried to obtain a support (I). Further, the support was treated with a 2.5% by weight aqueous solution of sodium silicate at 70 ° C. for 12 seconds, washed with water and dried to obtain a support (II).

[Production example of support having undercoat layer] On the support (I) or (II) obtained in the above-mentioned production example, the undercoat liquids (1) to ( 5) was applied and dried at 100 ° C. for 2 minutes to obtain supports (III) to (VII) having an undercoat layer.

[0078]

[Table 1]

Undercoating liquid (1) 4 g of carboxymethyl cellulose (Cellogen WS-A manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 4 g of magnesium acetate tetrahydrate 1000 g of distilled water

Undercoat liquid (2) 4 g of carboxymethylcellulose (Cellogen 6A manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 4 g of nickel acetate tetrahydrate 1000 g of distilled water

Undercoating liquid (3) Polyacrylic acid 4 g (Wako Pure Chemical Industries, Ltd., weight average molecular weight 25,000) Manganese acetate tetrahydrate 2.5 g Distilled water 1000 g

Undercoating liquid (4) Carboxymethyl cellulose 4 g (Serogen WS-C manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) Calcium acetate monohydrate 4 g Distilled water 800 g Methanol 200 g

Undercoating liquid (5) Acrylamide / methacrylic acid copolymer 4 g (polymerization molar ratio 3/1, weight average molecular weight 100,000) Nickel acetate tetrahydrate 4 g Distilled water 1000 g

Examples 1 to 5 and Comparative Examples 1 and 2 On the supports (III) to (V) and the comparative supports (0) and (II) obtained in the above Production Examples, heat-sensitive Layer (1)
The coating solutions were applied in combination as shown in Table 2 to prepare heat-sensitive lithographic printing original plates. Drying in oven at 100 ℃ 6
The drying was performed for 0 seconds, and the dry coating amount was 1.0 g / m ² .

Thermosensitive layer (1) Preparation of coating solution Polystyrene (Tg 100 ° C., average particle diameter 90 nm) dispersed in deionized water with a nonionic surfactant
In 8 g of a 20% by weight dispersion of the above, 0.024 g of polyoxyethylene nonylphenyl ether and 10.96 of deionized water were added.
g, and finally, with stirring, 8 g of a 5% by weight aqueous solution of polyvinyl alcohol (PVA205, manufactured by Kuraray Co., Ltd.).

An overcoat layer coating solution having the following composition was coated on the heat-sensitive layer of each substrate thus prepared in an amount of 20 coating solutions.
g / m ² and dried at 100 ° C. for 60 seconds to prepare a heat-sensitive planographic printing plate having an overcoat layer having a dry coating weight of 1.0 g / m ² .

(Coating Solution for Overcoat Layer) Polyacrylic acid (weight average molecular weight: 25,000) 1 g 20% by weight ethanol dispersion of carbon black stabilized by a nonionic surfactant 2.5 g 26.5 g methanol

The lithographic printing plate thus obtained was used as a trendsetter (40 W, 830 nm) manufactured by Creo, Canada.
(A plate setter equipped with a semiconductor laser) and exposed at an energy of 40 mJ / cm ² . The exposed plate was directly attached to a Harris Aurelia printing press without further processing, and printing was performed using a fountain solution containing a 10% by volume aqueous solution of isopropyl alcohol containing an etchant and ink. The results are shown in Table 2. In the table, ○ is good,
△ to △ indicate slightly inferior, × indicates inferior.

[0089]

[Table 2]

The above results indicate that the heat-sensitive lithographic printing plate according to the present invention is free from background contamination, has good ink dispensing properties, and has good printing durability of about 25,000 sheets. Is shown.

Examples 6 to 10 and Comparative Examples 3 and 4 Instead of the polystyrene fine particles of the heat-sensitive layer coating solution of Examples 1 to 5, polymethyl methacrylate fine particles (Tg 90 ° C.,
In the same manner as in Examples 1 to 5, except that an average particle size of 80 nm was used, and using the supports (III) to (VII) and the supports (0) and (II) for comparison, a heat-sensitive lithographic printing plate was used. Was prepared. Then, Examples 1 to 5 were performed using these printing original plates.
Exposure and printing were performed in the same manner as described above. Table 3 shows the results.

[0092]

[Table 3]

The above results indicate that the heat-sensitive lithographic printing plate according to the present invention is free from background contamination, has good ink dispensing properties, and has good printing durability of about 25,000 sheets. Is shown.

[0094]

According to the present invention, there is provided a heat-sensitive lithographic printing plate which can be directly mounted on a printing press and printed without any processing after exposure, and has good on-press developability. ,
In addition, it is possible to provide a heat-sensitive planographic printing plate which has high printing durability and is excellent in difficulty in soiling such as background stain and ink dispensing property in printing.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/09 501 G03F 7/09 501 F term (Reference) 2H025 AA02 AA12 AB03 AC08 AD01 BH02 BJ03 CB51 CB54 CC11 CC20 DA20 DA35 DA36 2H084 AA14 AA38 AE05 BB02 BB13 CC05 2H096 AA06 BA01 BA20 CA03 CA05 EA04 EA23 2H114 AA04 AA11 AA15 AA22 AA24 AA30 DA04 DA43 DA46 DA47 DA49 DA52 DA74 EA01 EA03 FA15 FA16 GA09

Claims (2)

[Claims] 1. A heat-sensitive lithographic printing original plate having a heat-sensitive layer containing hydrophobic thermoplastic fine particles melted by heat and a hydrophilic binder polymer on an aluminum support having an anodized film. The micropores of the film are subjected to pore-wide treatment, and the surface thereof has a water-soluble resin having a carboxyl group or a carboxylate group, and at least one metal selected from zinc, calcium, magnesium, barium, strontium, cobalt, manganese, and nickel. A heat-sensitive lithographic printing plate having an undercoat layer containing a water-soluble salt of: 2. The heat-sensitive lithographic printing plate according to claim 1, which is image-exposed with a laser beam, and is directly mounted on a printing machine for printing, or after being mounted on the printing machine, is then irradiated with the laser beam on the printing machine. A plate making and printing method for a heat-sensitive lithographic printing original plate, which is exposed and printed as it is.