JP2001010248A - Original plate of direct writing-type lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a negative direct writing-type waterless lithographic printing plate excellent in plate durability and image reproducibility with an ink mileage kept good by anode-oxidizing the surface of an aluminum substrate in an original plate of a direct writing-type lithographic printing plate in which a thermosensible layer and an ink repelling layer are formed on the aluminum substrate. SOLUTION: In the original plate of a direct writing-type lithographic printing plate in which at least a thermosensible layer and an ink repelling layer are formed in this order on an aluminum substrate, the surface of the substrate is anode-oxidized. In order to abode-oxidize the surface of the substrate, a high voltage is applied to an original plate in an electrolyte solution. A compound which is decomposed by being irradiated with laser beams or a thermosetting compound is preferably added into the thermosensible layer. A silicone rubber layer is preferable as the ink repelling layer. As the silicon rubber layer, either an addition polymerization type or a condensation polymerization type can be used. In this way, a negative direct writing-type lithographic printing plate excellent in plate durability and image reproducibility is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct drawing type lithographic printing plate precursor that can be directly made by laser light.
In particular, the present invention relates to a direct drawing type waterless planographic printing plate precursor capable of printing without using dampening solution.

[0002]

2. Description of the Related Art A so-called direct drawing type plate making, in which an offset printing plate is produced directly from an original without using a plate making film, is simple, which does not require skill, rapidity in which a printing plate can be obtained in a short time, Taking advantage of features such as rationality that can be selected from various systems according to quality and cost, the company has begun to enter not only the light printing industry but also the fields of general offset printing and flexographic printing. In particular, a new type of various direct-drawing lithographic printing plates has recently been developed with the rapid progress of output systems such as a prepress system, an image setter, and a laser printer. These direct-drawing lithographic printing plates can be classified according to plate-making methods, such as a method of irradiating a laser beam, a method of writing with a thermal head, a method of partially applying a voltage with a pin electrode, an ink repellent layer or an ink-coated layer by inkjet. And the like. Above all, the method using laser light is resolution,
It is superior to other methods in terms of plate making speed and there are many types.

[0003] The printing plate using the laser light further includes:
There are two types: a photon mode by photoreaction and a heat mode in which photothermal conversion is performed to cause a thermal reaction. In particular, the heat mode method has an advantage that it can be handled in a bright room, and its usefulness has recently been reviewed due to the rapid progress of a semiconductor laser as a light source.

For example, US Pat. No. 5,339,737, US Pat. No. 5,353,705, JP-A-6-55723, US Pat. No. 5,378,580, JP-A-7-1647.
73, JP-A-6-186750, JP-A-7
-309001, JP-A-9-104182, JP-A-9-146264, JP-A-9-146
265, JP-A-9-236927, JP-A-9-244228 and U.S. Pat. No. 5,487,733.
8, US Patent No. 5,385,092, US Patent No. 564
No. 9486, U.S. Pat. No. 5,704,291, and U.S. Pat. No. 5,570,636 describe a direct drawing type waterless planographic printing plate precursor using a laser beam as a light source, a plate making method thereof, and the like.

[0005] The heat-sensitive layer of the printing plate precursor of this thermal destruction method is
Carbon black is mainly used as a laser light absorbing compound, and nitrocellulose is used as a thermal decomposition compound. The carbon black is converted into thermal energy by absorbing laser light, and the heat destroys the heat-sensitive layer. Finally, by removing this portion by development, the silicone rubber layer on the surface is simultaneously peeled off to form an ink-coated portion.

However, in this printing plate, since the image is formed by destroying the heat-sensitive layer, the depth of the cells in the image area becomes deep, and the ink depositing property at minute dots is poor, and the ink mileage is poor. There was a problem. Further, there is also a problem that a crosslinked structure is formed in order to easily cause the heat-sensitive layer to be thermally destroyed, and the printing durability of the printing plate is poor. Furthermore, this printing plate has a problem that the sensitivity is low and a high laser light intensity is required to destroy the heat-sensitive layer.

In Japanese Patent Application Laid-Open No. 9-239943, a laser light is converted into heat to reduce the adhesion to the silicone rubber layer, and the solid content is 10 to 2%.
There has been proposed a heat mode fountain solution-free lithographic printing plate precursor having an addition type silicone rubber layer containing 0% by weight of an organohydrogensiloxane. However,
In this proposal, the heat-sensitive layer is basically composed of carbon black and nitrocellulose, and is of a type that is removed by development after laser irradiation.Because the ink-receiving layer is a primer layer below the heat-sensitive layer, It has a problem of ink mileage and a problem of intensity of laser light required for plate making. Japanese Patent Application Laid-Open No. 9-244228 discloses a technique in which high sensitivity can be attained by including hollow polymer fine particles in a primer layer. However,
The problem of ink mileage remained.

Japanese Patent Application Laid-Open No. 9-239942 describes a peeling development type printing plate containing a substance which generates an acid in a laser sensitive layer and a polymer compound which is decomposed by the action of an acid. Since two steps, a light irradiation step and a heating step, are required, the steps are complicated, and there is a problem inherent in peeling development that reproducibility of fine halftone dots is poor.

In addition, US Pat. No. 5,379,698, JP-A-7-314934, JP-A-9-236927.
In Japanese Patent Application Laid-Open Publication No. H10-157, a direct drawing type waterless lithographic printing plate using a metal thin film as a heat-sensitive layer is described. This printing plate material has a very thin heat-sensitive layer, so that a very sharp image can be obtained, which is advantageous in terms of the resolution of the printing plate. There has been a problem that the heat-sensitive layer at the line portion is peeled off, ink adheres, and becomes a defect on printed matter.

[0010] In addition to the lithographic printing plate using a laser beam as described above, a heat-bonding direct drawing type waterless lithographic printing plate is considered particularly as a direct drawing type waterless lithographic printing plate. In this type of plate material, the silicone rubber layer in the laser beam irradiating portion selectively remains, and functions as a non-image portion. Such a type of plate material is disclosed in, for example,
JP-A-8794, JP-A-9-80745, JP-A-9-120157, JP-A-9-197659, and the like. Japanese Patent Application Laid-Open No. 9-120157 discloses a plate material in which an acid generated by laser light irradiation is used as a catalyst to promote a reaction of a photosensitive layer to reproduce an image. However, in order to proceed the reaction after the generation of the acid, a step of heat treatment was required. Further, since the time from the generation of the acid to the heat treatment affects the image reproducibility, there is a problem that the image reproducibility becomes unstable. JP-A-9-80745, JP-A-9-80745
The plate material proposed in Japanese Patent Application No. 197 659 also contains a compound capable of generating an acid upon irradiation with actinic light and a compound having a bond capable of reacting in the presence of an acid in the photosensitive layer. Thereafter, since the reaction proceeds using the generated acid, it has the same problem as described above.
Further, as a fundamental problem of the heat bonding type, since the area of the non-image area occupies 60 to 70% in the printing plate,
There is a problem that the laser irradiation time for producing one printing plate becomes longer, and as a result, the life of the laser irradiator is shortened.

As the development of the direct-drawing printing plate progresses, the technology of on-press plate making, in which laser irradiation is performed on a printing machine, developed, and printing is performed as it is, is also under development. Japanese Patent Application Laid-Open No. 9-300837 is an example of this, and proposes a recording plate material for on-press plate making comprising a foam layer, a silicone resin layer, and a base film layer which are foamed by receiving a laser beam on a film substrate. Have been. In this plate material, the silicone rubber layer which is distorted by foaming of the foam layer is to be developed by peeling the base film, but there is a problem inherent in peeling development that reproducibility of fine halftone dots is poor. I was

[0012]

SUMMARY OF THE INVENTION The present invention solves all of the drawbacks of the prior art and provides a negative type direct drawing type water having excellent printing durability and excellent image reproducibility while maintaining good ink mileage. It is an object to provide a lithographic printing plate.

[0013]

In order to solve the above problems, the present invention mainly has the following constitution. That is,
A direct drawing type lithographic printing plate precursor having at least a heat-sensitive layer and an ink repellent layer on an aluminum substrate in this order, wherein the surface of the aluminum substrate is anodized. The original version. "

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

A feature of the present invention is a direct-drawing lithographic printing plate precursor having at least a heat-sensitive layer and an ink repellent layer in this order on an aluminum substrate, wherein the aluminum substrate has an anodized aluminum substrate. It is to be.

The lithographic printing plate precursor of the present invention using an anodized aluminum substrate has excellent printing durability.
The reason is considered to be that the adhesion between the aluminum substrate and the heat-sensitive layer is strong, so that the adhesion is not destroyed by repeated printing.

The aluminum substrate having an anodized surface used in the present invention can be obtained by applying a high voltage to an aluminum base plate in an electrolyte solution. Specifically, a direct current or an alternating current is applied to an aluminum plate in an aqueous solution or a non-aqueous solution using phosphoric acid, sulfuric acid, nitric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, or a combination of two or more of these. An anodic oxide film can be formed on the aluminum substrate surface. Anodizing conditions cannot be determined unconditionally because they vary depending on the electrolytic solution used, but generally the concentration of the electrolytic solution is 1 to 80%,
Liquid temperature 5 to 70 ° C, current density 0.5 to 60 amps / dm
^{2. The} appropriate range is 1 to 100 V for voltage and 10 to 100 seconds for electrolysis time. Among these anodized film treatments,
A method of performing anodic oxidation using sulfuric acid or phosphoric acid as an electrolytic bath is preferable.

The heat-sensitive layer of the present invention preferably contains a compound decomposable by the action of laser irradiation and / or a thermosetting compound.

As a compound that can be decomposed by the action of laser irradiation, the compound itself does not absorb laser light,
The compound may be decomposed by the action of another compound that absorbs laser light, or the compound itself may be decomposed by absorbing laser light.

The compound itself does not absorb laser light, but as a compound decomposed by the action of another compound that absorbs laser light, nitro compounds such as ammonium nitrate, potassium nitrate, sodium nitrate, carbonate compound, nitrocellulose and the like, Organic peroxides such as benzoyl peroxide and perbenzoic acid ester, inorganic peroxides, azo compounds such as polyvinylpyrrolidone, azodicarbonamide, azobisisobutyronitrile, and nitroso compounds such as N, N'-dinitropentamethylenetetramine Compounds, azide compounds, diazo compounds or sulfonyl hydrazide compounds such as p-toluenesulfonylhydrazine and p, p'-oxybis (benzenesulfohydrazine), and other low-molecular and high-molecular hydrazine derivatives can also be mentioned. Furthermore, compounds that generate an acid or an amine under the action of laser light and compounds that decompose under the action of the generated acid or amine can also be used in the present invention. The content of such a compound is from 0.1 to 70% by weight, preferably from 1 to 50% by weight, based on the total heat-sensitive layer composition.
%, More preferably 5 to 30% by weight.

As another compound that absorbs laser light, a known photothermal conversion material can be used. Specific examples of the light-heat conversion material include black pigments such as carbon black, titanium black, aniline black, and cyanine black, phthalocyanine, naphthalocyanine-based green pigments, carbon graphite, and diamine-based metal complexes.
Dithiol-based metal complex, phenolthiol-based metal complex, mercaptophenol-based metal complex, water-containing inorganic compound, copper sulfate, chromium sulfide, silicate compound, titanium oxide, vanadium oxide, manganese oxide, iron oxide, cobalt oxide, oxidation Examples include metal oxides such as tungsten, hydroxides and sulfates of these metals. Among these, carbon black is preferred from the viewpoints of light-to-heat conversion rate, economy, and handleability.

In addition, a dye that absorbs infrared or near-infrared light, particularly a dye, is preferably used as a photothermal conversion material. Particularly preferred dyes are cyanine-based, phthalocyanine-based, naphthalocyanine-based, dithiol metal complex-based, piasurenium-based, squarylium-based, croconium-based, azo-based disperse dyes, bisazo-based, bisazostilbene-based, naphthoquinone-based, anthraquinone-based, Examples include perylene, polymethine, indoaniline metal complex dyes, intermolecular CT, benzothiopyran, spiropyran, nigrosine, thioindigo, nitroso, quinoline, and fulgide dyes, particularly dyes.

The content of these light-to-heat converting substances is preferably 1 to 40% by weight, more preferably 5 to 25% by weight, based on the whole heat-sensitive layer composition. When the content is 1% by weight or more, the effect of improving the sensitivity to laser light is large, and when the content is 40% by weight or less, the printing durability of the printing plate does not decrease.

As the compound which absorbs laser light and decomposes itself, among the dyes and pigments having the above-mentioned photothermal conversion action, those which are relatively easily decomposed can be exemplified. Particularly preferred dyes are cyanine-based, phthalocyanine-based, naphthalocyanine-based, dithiol metal complex-based, piasurenium-based, squarylium-based, croconium-based, azo-based disperse dyes, bisazo-based, bisazostilbene-based, naphthoquinone-based, anthraquinone-based, Examples include perylene, polymethine, indoaniline metal complex dyes, intermolecular CT, benzothiopyran, spiropyran, nigrosine, thioindigo, nitroso, quinoline, and fulgide dyes, particularly dyes. The content of these compounds is 1 to 4 with respect to the total heat-sensitive layer composition.
0% by weight is preferable, and 5 to 25% by weight is more preferable.
When the content is 1% by weight or more, the effect of improving the sensitivity to laser light is large, and when the content is 40% by weight or less, the printing durability of the printing plate does not decrease.

Compounds that can be decomposed by the action of laser irradiation include polymethine-based near-infrared absorbing dyes, phthalocyanine-based near-infrared absorbing dyes, cyanine-based near-infrared absorbing dyes, and dithiol metal complex-based near-infrared absorbing dyes. Dyes and the like are preferred, and a combination of these near-infrared absorbing dyes with at least one selected from organic peroxides, azo compounds, azide compounds, diazo compounds, and hydrazine derivatives is preferred.

It is preferred that the thermosensitive layer contains a thermosetting compound. The thermosetting compound in the present invention refers to a group of compounds in the heat-sensitive layer of the printing plate precursor, which still have the ability to be cured directly or indirectly by the action of laser irradiation. Examples of such thermosetting compounds include novolak resins and resole resins obtained by the condensation reaction of phenols such as phenol, cresol and xylenol with formaldehyde, phenol / furfural resins, furan resins, unsaturated polyesters, alkyd resins, urea Resin, melamine resin,
Examples thereof include, but are not limited to, guanamine resins, epoxy resins, diallyl phthalate resins, unsaturated polyurethane resins, and polyimide precursors.

[0027] In addition to the resin itself reacting as described above, a composition obtained by adding a heat-reactive crosslinking agent to a compound having a reactive functional group is also used in the present invention as a thermosetting compound. be able to. Examples of the crosslinking agent include known polyfunctional compounds having crosslinking properties, such as polyfunctional blocked isocyanate, polyfunctional epoxy compound, polyfunctional acrylate compound, metal chelate compound, polyfunctional aldehyde, polyfunctional mercapto compound, and polyfunctional alkoxy. Examples thereof include a silyl compound, a polyfunctional amine compound, a polyfunctional carboxylic acid, a polyfunctional vinyl compound, a polyfunctional diazonium salt, a polyfunctional azide compound, and hydrazine. Further, a known catalyst may be added to promote the reaction of the crosslinking agent. These crosslinking agents can be used alone or in combination of two or more.

Further, a compound which generates an acid or an amine under the action of heat and a compound which cures under the action of the generated acid or amine can be used in the present invention. Among such thermosetting compounds, a combination of a phenol resin and a metal chelate compound is particularly preferred.

The proportion of such a thermosetting compound in the thermosensitive layer is preferably 10 to 95% by weight, more preferably 30 to 70% by weight of the thermosensitive layer. When the amount of the thermosetting compound is 10% by weight or more, the effect of improving the solvent resistance of the image-forming part heat-sensitive layer by the heat-curing of the heat-sensitive layer can be seen.
On the other hand, when the content is 95% by weight or less, the problem of image forming property due to laser irradiation due to the relatively small amount of the thermally decomposable compound and the light-to-heat conversion substance does not occur.

In addition, the heat-sensitive layer may contain a binder polymer, a surfactant and various additives.

Specific examples of the binder polymer include acrylates such as polymethyl methacrylate and polybutyl methacrylate, homopolymers and copolymers of methacrylates, and styrene monomers such as polystyrene, α-methylstyrene, and hydroxystyrene. Homopolymers and copolymers, various synthetic rubbers such as isoprene and styrene-butadiene, homopolymers and copolymers of vinyl esters such as polyvinyl acetate and vinyl chloride, and polyoxides such as polyethylene oxide and polypropylene oxide (Polyethers), polyesters, polyurethanes, polyamides, cellulose derivatives such as ethyl cellulose, cellulose acetate, phenoxy resin, methylpentene resin, polyparaxylylene resin, poly Such as E two-sulfide resin, and the like.

The content of these binders is preferably from 5 to 70% by weight, and more preferably from 10 to 50% by weight based on the total heat-sensitive layer composition.
% Is more preferred. When the content is 5% or more, printing durability and coating properties of the coating solution are good, and when the content is 70% by weight or less, there is no adverse effect on image reproducibility.

The thickness of the heat-sensitive layer is 0.1 to 1 in terms of the coating layer.
When it is 0 g / m ^2, it is preferable in terms of printing durability of the printing plate and excellent productivity because the diluting solvent is easily evaporated, and 0.5 to 7 g / m ^2.
m ² is more preferred.

When a laser is applied to the direct-drawing lithographic printing plate precursor having such a heat-sensitive layer, a compound decomposed by the action of the laser beam is decomposed on the surface of the heat-sensitive layer by the action of the light-to-heat conversion material. The photothermal conversion substance itself may be decomposed by the action of the laser beam. At that time, it is preferable to generate a gas such as nitrogen or oxygen. The decomposition of such a compound and the action of gas weaken the adhesive force between the silicone rubber layer and the heat-sensitive layer. On the other hand, inside the heat-sensitive layer of the laser irradiation part, the curing of the thermosetting compound proceeds. As a result, the solvent resistance of the heat-sensitive layer at the laser-irradiated portion is improved. As a result, a printing plate is obtained in which only the silicone rubber layer and the very surface of the heat-sensitive layer at the laser-irradiated portion have been separated by the subsequent development treatment.

In the plate thus obtained, the heat-sensitive layer of the image area has a high solvent resistance and remains, and therefore has the advantage that the reproducibility of fine halftone dots and the ink mileage are good.

As the ink repellent layer in the present invention, a hydrophilic layer made of vinyl alcohols or the like, a hydrophilic layer containing acrylic acid or acrylate, sulfonic acid or sulfonic acid salt, JP-A-8-282142, JP-A-8-2
No. 82144, JP-A-8-292558, JP-A-9-54425, and the like, a hydrophilic swelling layer, a silicone rubber layer, a layer containing a fluorine compound, and the like, which can be used, are preferred. Is a silicone rubber layer. As the silicone rubber layer, any of an addition polymerization type and a condensation polymerization type can be used.

The components constituting the addition polymerization type silicone rubber layer include vinyl group-containing polydimethylsiloxane,
It contains a SiH group-containing polysiloxane, a reaction inhibitor for the purpose of controlling the curing rate, and a curing catalyst.

The vinyl group-containing polydimethylsiloxane is
It has a structure represented by the following general formula (I) and has a vinyl group at a molecular terminal and / or in a main chain.

[0039]

Embedded image (In the formula, n represents an integer of 2 or more, and R ¹ and R ^{2 each} have 1 carbon atom.
~ 50 substituted or unsubstituted alkyl groups, having 2 to 2 carbon atoms
50 substituted or unsubstituted alkenyl groups, having 4 to 4 carbon atoms
At least one group selected from the group consisting of 50 substituted or unsubstituted aryl groups, which may be the same or different; ) In the above formula, R ¹ and R ² are all 5
It is preferable that 0% or more is a methyl group from the viewpoint of ink repellency of the printing plate. Further, the molecular weight may be in the range of thousands to hundreds of thousands, but from the viewpoint of handleability, ink repellency and scratch resistance of the obtained printing plate, the weight-average molecular weight is 10,000 to 200,000, and more preferably 3 to 100,000. It is preferable to use a material of 10,000 to 150,000.

Examples of the SiH group-containing polysiloxane include compounds having a SiH group in the molecular chain or at the terminal, such as those represented by the following general formulas (II) to (V).

[0041]

Embedded image

[0042]

Embedded image

[0043]

Embedded image (In the formulas (II) to (IV), n is an integer of 1 or more, and m is an integer of 1 or more.)

[0044]

Embedded image

S in SiH group-containing polysiloxane
The number of iH groups is 2 or more in one molecule, and more preferably 3 or more.
Preferably, the number is at least. The addition amount of the SiH group-containing polysiloxane is 3% of the total composition of the silicone rubber layer.
It is preferably from 20 to 20% by weight, more preferably from 5 to 15% by weight. Speaking of the quantitative ratio to polydimethylsiloxane, the molar ratio of SiH group / vinyl group of polydimethylsiloxane is preferably 1.5 to 30, and more preferably 10 to 20. When the molar ratio is 1.5 or more, the curing of the silicone rubber layer is sufficient. When the molar ratio is 30 or less, there is no embrittlement of the physical properties of the rubber, which adversely affects the scratch resistance of the printing plate. Not even.

Examples of the reaction inhibitor include a nitrogen-containing compound, a phosphorus compound, and an unsaturated alcohol, and an alcohol having an acetylene group is preferably used.
The preferable addition amount of the reaction inhibitor is 0.01 to 10% by weight in the silicone rubber composition, more preferably 1 to 10% by weight.
~ 5% by weight.

The curing catalyst is a Group III transition metal compound, preferably a platinum compound. Specific examples thereof include platinum alone, platinum chloride, chloroplatinic acid, olefin-coordinated platinum, an alcohol-modified complex of platinum, and methyl methyl of platinum. A vinyl polysiloxane complex can be given as an example. The amount of such a curing catalyst is 0.01 to 20% by weight, and more preferably 0.1 to 10% by weight as a solid content in the silicone rubber layer.
It is preferable that When the amount of the catalyst to be added is 0.01% by weight or more, the silicone rubber layer is sufficiently cured, and there is no problem in adhesion to the heat-sensitive layer. On the other hand, when the content is 20% by weight or less, the pot life of the silicone rubber layer solution is not adversely affected. In terms of the amount of metal such as platinum in the silicone rubber layer composition, 1
It is preferably from 0 to 1000 ppm, more preferably from 100 to 500 ppm.

Further, in addition to these compositions, a hydroxyl group-containing organopolysiloxane, a hydrolyzable functional group-containing silane or a hydrolyzable functional group-containing siloxane, which is a composition of the condensation type silicone rubber layer, improves the rubber strength. It may contain a known filler such as silica for the purpose, and a known silane coupling agent, titanate-based coupling agent, and aluminum-based coupling agent for the purpose of improving the adhesiveness. As the silane coupling agent, alkoxysilanes, acetoxysilanes, ketoximine silanes and the like are preferable, and those having a vinyl group and ketoximine silanes are particularly preferable.

The components constituting the condensation polymerization type silicone rubber layer include a hydroxyl group-containing polydimethylsiloxane, a crosslinking agent (deacetic acid type, deoxime type, dealcohol type, deamine type, deacetone type, deacetone type, deamidation type). , Deaminoxy type, etc.), and a curing catalyst.

The hydroxyl-containing polydimethylsiloxane is also
It has a structure represented by the general formula (I). Hydroxyl group is a molecule
Can be located at the termini and / or in the backbone
However, those preferably used have a hydroxyl group at the molecular weight end.
Is what you do. R in the general formula ¹, R^TwoAbout
The fact that more than 50% of the total is methyl groups
It is preferable in terms of ink repulsion. Thousands to number as molecular weight
100,000 items can be used, but their handling and obtained seals
From the viewpoint of ink repulsion and scratch resistance of the printing plate,
Use those with a child volume of 10,000 to 200,000 and even 30,000 to 150,000
Preferably.

Examples of the crosslinking agent used in the condensation polymerization type silicone rubber layer include acetoxysilanes, alkoxysilanes, ketoximine silanes, and allyloxysilanes represented by the following general formula (VI). Can be. (R ³ ) _4-n SiX _n (VI) (wherein, n represents an integer of 2 to 4, and R ³ represents a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 or more carbon atoms, or X represents a combined group of
Represents a hydrolyzable functional group selected from a halogen atom, an alkoxy group, an acyloxy group, a ketoximine group, an aminooxy group, an amide group, and an alkenyloxy group. In Formula (VI), the number n of the hydrolyzable groups is preferably 3 or 4.

Specific compounds include methyltriacetoxysilane, ethyltriacetoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetraethoxysilane and tetraethoxysilane. Propoxysilane, vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltriethoxysilane,
Allyltriethoxysilane, vinyltriisopropoxysilane, vinyltrisisopropenoxysilane, vinylmethylbis (methylethylketoximine) silane, methyltri (methylethylketoximine) silane, vinyltri (methylethylketoximine) silane, tetra (methylethylketoximine) Examples include, but are not limited to, silane, diisopropenoxydimethylsilane, triisopropenoxymethylsilane, and tetraallyloxysilane. Among these, acetoxysilanes and ketoximinesilanes are preferred from the viewpoints of the curing rate of the silicone rubber layer, handleability, and the like.

The amount of the crosslinking agent represented by the general formula (VI) is preferably 1.5 to 20% by weight, more preferably 3 to 10% by weight of the total composition of the silicone rubber layer. . Speaking of the quantitative ratio to polydimethylsiloxane, the molar ratio of functional group / hydroxyl group of polydimethylsiloxane is preferably 1.5 to 10.0. When the molar ratio is 1.5 or more, gelation of the silicone rubber layer solution does not occur. Conversely, when the molar ratio is 10.0 or less, there is no embrittlement of rubber properties and the scratch resistance of the printing plate. It does not have any adverse effects.

Acetic acid, propionic acid,
Organic carboxylic acids such as maleic acid; acids such as toluenesulfonic acid and boric acid; alkalis such as potassium hydroxide, sodium hydroxide and lithium hydroxide; amines; metal alkoxides such as titanium tetrapropoxide and titanium tetrabutoxide; and iron Metal diketenates such as acetylacetonate and titanium acetylacetonate dipropoxide, and organic acid salts of metals can be given. Among them, it is preferable to add an organic acid salt of a metal, particularly preferably an organic acid salt of a metal selected from tin, lead, zinc, iron, cobalt, calcium, and manganese. Specific examples of such compounds include dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, zinc octylate, and iron octylate. The amount of such a curing catalyst is 0.01 to 20% by weight as a solid content in the silicone rubber layer,
More preferably, it is 0.1 to 10% by weight. When the amount of the catalyst to be added is 0.01% by weight or more, the curing of the silicone rubber layer becomes sufficient, and there is no problem in the adhesiveness to the heat-sensitive layer. On the other hand, when the content is 20% by weight or less, the pot life of the silicone rubber layer solution is not adversely affected.

Further, in addition to these compositions, a known filler such as silica and a known silane coupling agent may be contained for the purpose of improving rubber strength. Thickness of the silicone rubber layer is preferably 0.5 to 20 g / m ^2, more preferably 1 to 4 g / m ^2. 0.5 film thickness
When the g / m ² or more is not less than 20 g / m ² , the ink repellency, scratch resistance and printing durability of the printing plate are not reduced. The properties and ink mileage are also good.

The direct-drawing lithographic printing plate precursor according to the present invention is designed to prevent the heat of the irradiated laser from escaping to the substrate.
It is effective to provide a heat insulating layer. A well-known primer layer conventionally used to strengthen the adhesiveness between the substrate and the ink receiving layer may be used as a substitute.

When the heat insulating layer is used in the present invention, it is preferable that the following conditions are satisfied. That is, an effect is obtained that the aluminum substrate and the ink receiving layer are well adhered to each other, are stable over time, and have high resistance to a developing solution and a solvent used for printing.

Those satisfying such conditions include those containing epoxy resin, polyurethane resin, phenol resin, acrylic resin, alkyd resin, polyester resin, polyamide resin, urea resin, polyvinyl butyral resin, casein, gelatin and the like. No. 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.

It is also preferable to add an additive such as a pigment or a dye to the heat insulating layer to improve plate inspection.

The thickness of the heat insulating layer is 0.5 to 50 as a coating layer.
preferably ^{g / m 2, 1~10g / m} 2 is more preferable. By making the thickness 0.5 g / m ² or more, the effect of blocking morphological defects and chemical adverse effects on the substrate surface is improved,
When the content is 50 g / m ² or less, it is advantageous from an economic viewpoint.

A direct drawing type lithographic printing plate precursor may be laminated with a protective film or formed with a protective layer for the purpose of protecting the ink repellent layer. Examples of the protective film include a polyester film, a polypropylene film, a polyvinyl alcohol film, a saponified ethylene vinyl acetate copolymer film, and a polyvinylidene chloride film. The thus obtained direct drawing type lithographic printing plate precursor is exposed imagewise with a laser beam after the protective film is peeled off or from above the protective film.

The direct drawing type lithographic printing plate precursor thus obtained is directly drawn by a step of generating a decomposition product on the surface of the heat-sensitive layer by the action of laser irradiation and a step of promoting curing inside the heat-sensitive layer by the action of laser irradiation. A planographic printing plate can be manufactured.

The laser light source used in the plate-making exposure step of the present invention has an emission wavelength range of 300 nm to 1500.
Among them, a semiconductor laser or a YAG laser having an emission wavelength region near the near infrared region is preferably used. Specifically, from the viewpoint of handleability of the plate material in the light room, 780 n
Laser beams having wavelengths of m, 830 nm, and 1064 nm are preferably used for plate making.

In the present invention, a decomposition product is generated on the surface of the heat-sensitive layer by laser irradiation, and the inside of the heat-sensitive layer is further cured by laser irradiation.

The original plate after the laser irradiation is developed by a friction treatment in the presence or absence of water or an organic solvent. The rubbing treatment is performed by wiping the plate surface with a non-woven fabric, absorbent cotton, cloth, sponge, or the like impregnated with a developer, or by rubbing the plate surface with a rotating brush while showering with tap water after pre-treating the plate surface with the following developer. be able to.

Examples of the developing solution used for the development treatment include water and water obtained by adding a surfactant to water,
Further, a polar solvent such as alcohol, ketone, ester or carboxylic acid is added to water, or at least one polar solvent is added to a solvent composed of at least one kind of aliphatic hydrocarbons or aromatic hydrocarbons. Or a polar solvent is used. A known surfactant can be freely added to the above-mentioned developer composition. Further, an alkali agent such as sodium carbonate, monoethanolamine, diethanolamine, diglycolamine, monoglycolamine, sodium silicate, potassium hydroxide, sodium borate and the like can be added. Among these, water or a mixture of water and a surfactant is preferable.

[0067]

[Example 1] A 0.24 mm-thick aluminum plate (1100 series alloy, manufactured by Sky Aluminum Co., Ltd.) was rolled off with 10% sodium hydroxide to remove the rolling oil adhering to the surface, and then washed in 20% nitric acid. After neutralization washing and water washing, 2% in 4% phosphoric acid solution
The electrolytic surface-roughening treatment was performed at 5 ° C. with an anode charge of 200 coulombs / dm ² . The following heat-sensitive layer was applied on this aluminum plate. Dry film thickness is 1.5 g / m ² , heat treatment is 100 ° C
X 1 minute.

<Thermal Sensitive Layer> (a) Carbon black (# 30, manufactured by Mitsubishi Chemical Corporation)
Light-to-heat conversion substance): 15 parts by weight (b) Nitrocellulose "Bergerac NC"
(Viscosity 1/2 second, nitrogen content 11.0%, S.N.
Manufactured by P.E. Japan; a compound that can be decomposed by the action of laser irradiation): 15 parts by weight (c) Iron (III) acetylacetonate (manufactured by Hanoi Chemicals): 10 parts by weight (d) " Sumilac “PC-1 (resole resin, manufactured by Sumitomo Durres Co., Ltd .; thermosetting compound): 50 parts by weight (e)“ SAMPLEN ”LQ-T1331 (polyurethane resin, manufactured by Sanyo Chemical Industries, Ltd.): 10 parts by weight (F) Tetrahydrofuran: 100 parts by weight (g) Dimethylformamide: 100 parts by weight (h) Methyl ethyl ketone: 700 parts by weight
The drying conditions were 120 ° C. × 1 minute (wet heat drying).

<Silicone Rubber Layer 1> (a) Polydimethylsiloxane (molecular weight of about 50,000
0, both ends are hydroxyl groups): 100 parts by weight (b) Vinyl tris (methylethylketoxime) silane: 8 parts by weight (c) Dibutyltin diacetate: 0.5 parts by weight (d) 3-aminopropyltriethoxysilane: 0 .5
Parts by weight (e) "Isopar" E (isoparaffinic hydrocarbon,
Exxon Chemical Co., Ltd.): 1400 parts by weight A 8 μm thick polypropylene film “Trefane” BO (Toray Industries, Inc.) was added to the laminate obtained as described above.
Was laminated using a calendar roller to obtain a direct-drawing waterless planographic printing plate precursor.

Thereafter, this printing plate precursor is referred to as “FX400-
AP "(plate making machine, manufactured by Toray Engineering Co., Ltd.) and a semiconductor laser (wavelength 830 nm, beam diameter 2
0 μm), exposure time 10 μs, irradiation energy 3
Exposure was performed at 00 mJ / cm ² .

In the printing plate after the exposure, only the heat-sensitive layer in the laser-irradiated portion was specifically gray, which suggests that some change has occurred.

Subsequently, the sample was immersed in "PP-F" (a pretreatment liquid for a lithographic positive mold without water, manufactured by Toray Industries, Inc.) for 1 minute and then water-containing "Hize Gauze" (manufactured by Asahi Chemical Industry Co., Ltd.) ) To obtain a negative waterless planographic printing plate from which only the silicone rubber layer in the portion irradiated with the laser beam was removed.

At this time, on the surface of the heat-sensitive layer in the laser-irradiated portion, the presence of fine powder presumed to be a decomposition product by laser irradiation was observed.

Further, the obtained printing plate was attached to a sheet-fed offset printing machine “HAMADA RS34L” (manufactured by Hamada Printing Machinery Co., Ltd.), and a waterless lithographic ink “Dryocolor NSI” indigo (Dainippon Ink Chemical Industry) Printing on high quality paper (62.5 kg / chrysanthemum) using the following method, a printed matter that faithfully reproduced the image was obtained, and continuous printing of 150,000 sheets was performed. Good printed matter was obtained.

Comparative Example 1 A direct-drawing waterless planographic printing plate precursor was obtained in the same manner as in Example 1 except that an untreated aluminum plate having a thickness of 0.24 mm was used. This plate was evaluated in the same manner as in Example 1. As a result of the evaluation, 3
An image could be formed with an exposure amount of 00 mJ / cm ² , but in printing, background staining occurred when 70,000 sheets were printed, and the plate with the background contamination was confirmed. It turned out that it was partially destroyed.

Example 2 A 0.24 mm-thick aluminum plate (1100 alloy manufactured by Sky Aluminum Co., Ltd.) was rolled with 10% sodium hydroxide to remove the rolling oil adhering to the surface.
After neutralizing and washing in a 1% nitric acid solution and washing with water, electrolytic surface roughening treatment was performed in a 1% sulfuric acid solution at 25 ° C. with an anode charge of 300 coulombs / dm 2. A heat-sensitive layer and a silicone rubber layer were provided on this aluminum plate in the same manner as in Example 1 to obtain a direct-drawing waterless planographic printing plate precursor. This plate was evaluated in the same manner as in Example 1. As a result of the evaluation, 300
An image could be formed with an exposure amount of mJ / cm ² . In the printing, continuous printing of 150,000 sheets was performed, but a good printed matter was obtained without any background stain.

[0077]

According to the present invention, a negative direct drawing type lithographic printing plate having excellent printing durability and good image reproducibility can be obtained.

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Claims (3)

[Claims] 1. A direct drawing type lithographic printing plate precursor having at least a heat-sensitive layer and an ink repellent layer in this order on an aluminum substrate, wherein the surface of the aluminum substrate is anodized. Lithographic printing plate precursor. 2. The lithographic printing plate precursor according to claim 1, wherein the heat-sensitive layer contains a compound decomposable by the action of laser irradiation and / or a thermosetting compound. 3. The lithographic printing plate precursor according to claim 1, wherein the ink repellent layer is a silicone rubber layer.