JP2006146014A - Negative-type lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative-type lithographic printing plate free of the influence on printing durability and improved in staining properties and dots of a halftone dots. <P>SOLUTION: The negative-type lithographic printing plate has a photopolymerizable photosensitive layer on an aluminum support, obtained by treating an anodized aluminum plate with a treating solution containing an alkali metal silicate and an alkali-soluble polymer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a negative lithographic printing plate having no influence on printing durability, no stain, and no halftone dot shading in a photosensitive lithographic printing plate having an aluminum plate as a support.

  In recent years, computer-to-plate (CTP) technology has been developed to output directly on a printing plate without outputting it on film based on digital data created on a computer. Various plate setters equipped with various lasers as output machines The development of photosensitive lithographic printing plates suitable for these has been actively conducted. In particular, in an output device using a semiconductor laser or a YAG laser that emits light in the near infrared region of 750 nm or more, a high-power laser with a light source output of several hundreds mW to several watts is mounted, so the energy is extremely high. Image formation is possible. Examples of such photosensitive lithographic printing plates compatible with CTP are, for example, JP-A-7-20629, 7-271029, 9-185160, 9-197671, 9-222731, 9-239945. The decomposition of the latent acid generator using heat generated by photothermal conversion in the combination of the latent acid generator and the near-infrared absorbing dye as described in JP-A-10-142780 and the laser irradiation A negative-type image forming method using acid-catalyzed thermal crosslinking using an acid generated in a part is disclosed. Alternatively, as a system in which photon mode recording, which is an application of conventional high-sensitivity photopolymer technology, is applied to near-infrared light, for example, JP-A Nos. 2000-122274, 2000-131833, 2000-181559, 2000 No. 194124 discloses a negative type with high sensitivity by using various dyes that spectrally sensitize the photopolymerization initiator in near infrared light in a photopolymer system containing a photopolymerization initiator and an ethylenically unsaturated compound. Recording material is given.

  On the other hand, as a method of hydrophilizing the lithographic printing plate, there are a method of treating with an alkali developer containing silicate and a method of directly hydrophilizing an aluminum support. Examples of directly hydrophilizing an aluminum support are described in U.S. Pat. Nos. 2,714,066, 3,181,461, 3,280,734 or 3,902,734. As described above, there are a method in which an aluminum support provided with an anodic oxide coating is immersed in an aqueous solution of sodium silicate, that is, a silicate treatment, or an electrolytic treatment to make it hydrophilic. Further, an aluminum support provided with an anodized film as described in U.S. Pat. Nos. 3,276,868 and 4,153,461, polyvinyl phosphonic acid, or vinyl phosphonic acid, acrylic acid, and A method of hydrophilizing using a copolymer made of vinyl acetate is known.

  However, although the above-described method of hydrophilizing the aluminum support can be expected to have a hydrophilizing effect, it has not yet been able to sufficiently prevent soiling and halftone dot shading. Here, halftone mesh means that 90% or more of the mesh is entangled with ink and the halftone dot of the printed matter becomes solid.

Moreover, as coexistence of printing durability and stain resistance of non-image areas, JP 2003-233169 (Patent Document 1) describes that a silicate-treated aluminum support is treated with an aqueous solvent containing polyvinylphosphonic acid. Has been. Japanese Patent Application Laid-Open No. 2000-122300 (Patent Document 2) describes that a layer containing a compound having an alkylene oxide group and a silicate is included. However, these methods have not been able to provide sufficient effects with respect to the soiling and halftone dot shadows, which are the problems of the present invention.
JP 2003-233169 A JP 2000-122300 A

  Accordingly, an object of the present invention is to provide a negative type lithographic printing plate which has no influence on printing durability and has improved stain resistance and halftone dot shadows.

The above object of the present invention has been achieved by the following means.
1. A negative lithographic printing plate comprising a photopolymerizable photosensitive layer on an aluminum support obtained by treating an anodized aluminum plate with a treatment solution containing an alkali metal silicate and an alkali-soluble polymer. .
2. The negative lithographic printing plate as described in 1 above, wherein the photosensitive layer contains a polymer having an ethylenically unsaturated double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component.
3. The negative lithographic printing plate as described in 1 above, wherein the photosensitive layer contains an organic boron salt and a dye having absorption in a wavelength region of 750 nm or more.

  According to the present invention, a negative lithographic printing plate having improved stain resistance and halftone dot shadowing (90% or more) can be obtained without reducing printing durability by the above means.

  The aluminum support of the present invention will be described in detail below. First, a treatment liquid containing an alkali metal silicate and an alkali-soluble polymer for treating an anodized aluminum plate will be described.

The treatment liquid for treating the anodized aluminum support of the present invention is a solution containing an alkali metal silicate and an alkali-soluble polymer. As the alkali metal silicate, sodium silicate, potassium silicate, lithium silicate and the like are used, and potassium silicate is preferable. The concentration of the alkali metal silicate in the treatment liquid used for the silicate treatment is preferably in the range of 0.5 to 10% by mass in terms of SiO ₂ , and more preferably in the range of 1 to 6% by mass.

  The treatment liquid containing the alkali metal silicate preferably further contains an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide or lithium hydroxide. Among the alkali metal hydroxides, potassium hydroxide is preferable. Is preferred. The concentration of the alkali metal hydroxide in the treatment liquid is preferably in the range of 0.5 to 5% by mass, and the pH of the treatment liquid at 25 ° C. is preferably 10.5 or more, and is in the range of 10.5 to 13.5. Is more preferable, and the range of 11.0 to 13.0 is particularly preferable.

The molar ratio of SiO ₂ / M ₂ O (M represents an alkali metal) in the treatment liquid is preferably in the range of 0.5 to 3.0, more preferably in the range of 0.8 to 2.5.

M in the above-mentioned SiO ₂ / M ₂ O represents an alkali metal, but the treatment liquid used in the silicate treatment of the present invention preferably contains potassium silicate, and therefore 50 mol% or more of the alkali metal (M). Is preferably potassium, more preferably 70 mol% or more is potassium, and even more preferably 100 mol% is potassium.

  The temperature of the treatment liquid when performing the silicate treatment can be about 5 to 80 ° C., but is preferably less than 70 ° C., more preferably 65 ° C. or less. For the treatment time, for example, the time for immersing the aluminum plate in the treatment liquid is preferably 1 to 60 seconds, and particularly preferably 3 to 50 seconds.

The alkali-soluble polymer contained in the treatment liquid is not particularly limited as long as it is a polymer that can be dissolved in an alkaline aqueous solution having a pH of about 9 or more. For example, —COOH, —PO ₃ H ₂ , —SO ₃ H , —SO ₂ NH ₂ , —SO ₂ NH—SO ₂ —, and polymers containing groups such as SO ₂ —NH—CO—.

  Specific examples of such a polymer include maleic anhydride-modified polybutadiene, carboxyl group-containing styrene butadiene copolymer, maleic ester resin, β-methacryloyloxyethyl-N- (p-trisulfonyl) -carbamate polymer, And copolymers of monomers similar to those constituting these polymers with other monomers, vinyl acetate / crotonic acid copolymers, styrene / maleic anhydride copolymers, methacrylate esters / methacrylic acid copolymers, methacrylic acid / styrene / acrylonitrile copolymers, Examples thereof include cellulose acetate phthalate and the like, but are not limited thereto. Among these, a copolymer of a hydrophobic vinyl monomer and a monomer for imparting alkali solubility is preferable. For example, the hydrophobic vinyl monomer is preferably styrene, and the monomer imparting alkali solubility is preferably a carboxyl group-containing monomer, such as maleic anhydride or (meth) acrylic acid. The molar ratio of the hydrophobic vinyl monomer and the carboxyl group-containing monomer is preferably in the range of 20:80 to 80:20. These alkali-soluble polymers may be used alone or in combination of two or more. The amount used is preferably 0.1 to 15% by mass, and more preferably 0.5 to 5% by mass.

  In the aluminum support of the present invention, the aluminum plate used is a plate-like body such as pure aluminum or an aluminum alloy containing a small amount of different atoms. Examples of the hetero atoms include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The amount of different atoms is usually 10% by weight or less. The aluminum plate for a support suitable for the present invention is a pure aluminum plate. However, a completely pure aluminum plate is difficult to produce in terms of smelting technology, so it is preferable that it contains as few hetero atoms as possible. Moreover, if it is an aluminum alloy plate of the content of the above grade, it can be said that it is a raw material applicable to this invention. Thus, the composition of the aluminum plate used in the present invention is not particularly limited, and conventionally known and publicly available materials can be appropriately used. The thickness of the aluminum plate used in the present invention is usually about 0.1 mm to 0.5 mm.

  Prior to the anodic oxidation described below, the aluminum plate is subjected to a degreasing treatment and a graining treatment, for example, by treatment with a surfactant or an alkaline aqueous solution, in order to remove rolling oil on the surface. The graining method includes a method of mechanically roughening the surface, a method of dissolving the surface electrochemically, and a method of selectively dissolving the surface chemically. As a method for mechanically roughening the surface, a known method called a ball polishing method, a brush polishing method, a blast polishing method, a buff polishing method, or the like can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as described in US Pat. No. 4,476,006, a method in which a mechanical surface roughening method and an electrochemical surface roughening method are combined can also be used.

The aluminum plate thus roughened is subjected to alkali etching treatment and neutralization treatment as necessary. Any electrolyte can be used as the electrolyte used for anodizing the aluminum plate as long as it forms a porous oxide film. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte. The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by weight solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 cm /. dm ² , voltage 1 to 100 V, electrolysis time 10 seconds to 50 minutes. The amount of the anodic oxide coating is suitably 0.1 to 10 g / m ^2, but preferably 1 to 6 g / m ² .

  The anodized film of the aluminum plate subjected to the above-described treatment may be subjected to a sealing treatment by exposing it to a steam atmosphere or immersing it in hot water before performing the silicate treatment of the present invention. When sealing with steam, pressurized or atmospheric steam is used. The treatment conditions in the case of using normal-pressure steam are suitably about 2 seconds to 2 minutes at a relative humidity of 70% or more and a steam temperature of 95 ° C. or more. When immersed in hot water, it is preferable to add various additives having an effect of promoting sealing to hot water.

  Next, the photosensitive layer used in the negative planographic printing plate of the present invention will be described. The photopolymerizable photosensitive layer contains a photopolymerizable initiator and a polymerizable monomer, oligomer or polymer. The photosensitive layer of the present invention preferably contains a polymer having an ethylenically unsaturated double bond in the side chain and a carboxyl group-containing monomer as a copolymerization component.

  A polymer having a polymerizable double bond in the side chain and having a carboxyl group-containing monomer as a copolymerization component will be described. As the carboxyl group-containing monomer, acrylic acid, methacrylic acid, acrylic acid 2-carboxyethyl ester, methacrylic acid 2-carboxyethyl ester, crotonic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, Examples include 4-carboxystyrene and the like.

  As monomers for introducing a polymerizable double bond into the polymer side chain, allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl-acrylate, 1-propenyl-methacrylate, β-phenyl-vinyl- Methacrylate, β-phenyl-vinyl-acrylate, vinyl methacrylamide, vinyl acrylamide, α-chloro-vinyl-methacrylate, α-chloro-vinyl-acrylate, β-methoxy-vinyl-methacrylate, β-methoxy-vinyl-acrylate, vinyl -Thio-acrylate, vinyl-thio-methacrylate and the like.

  The polymer used in the present invention is particularly preferably a polymer having a phenyl group substituted with a vinyl group in a side chain and a carboxy group-containing monomer as a copolymerization component. The phenyl group substituted with a vinyl group is bonded to the main chain directly or through a linking group, and the linking group is not particularly limited, and includes any group, atom, or a combination thereof. The phenyl group may be substituted with a substitutable group or atom, and the vinyl group is a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, It may be substituted with an aryl group, an alkoxy group, an aryloxy group or the like. More specifically, the polymer having a phenyl group in which a vinyl group is substituted on the side chain described above has a group represented by the following chemical formula 1 in the side chain.

In the formula, Z ₁ represents a linking group, and R ₁ , R ₂ , and R ₃ are a hydrogen atom, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, and an aryl group. A group, an alkoxy group, an aryloxy group, and the like, and these groups may be substituted with an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, a hydroxy group, or the like. R ₄ represents a substitutable group or atom. n ₁ represents 0 or 1, m ₁ represents an integer of 0 to 4, and k ₁ represents an integer of ₁ to 4.

The above general formula will be described in more detail. As the linking group for Z ₁ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₅ ) —, —C (O) —O—, —C (R ₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, and a group represented by the following chemical formula 2 alone or in combination of two or more. Here, R ₅ and R ₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

Examples of the heterocyclic group include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiatriazole ring, indole ring. , Indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, quinoxaline ring, etc. A nitrogen-containing heterocyclic ring, a furan ring, a thiophene ring, and the like, and a substituent may be bonded to these heterocyclic rings.
Although the example of group represented by Chemical formula 1 is shown below, it is not limited to these examples.

Among the groups represented by the above chemical formula 1, preferred ones exist. That is, it is preferable that R ₁ and R ₂ are hydrogen atoms and R ₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.). Furthermore, as the linking group for Z ₁ , those containing a heterocyclic ring are preferred, and those in which k ₁ is 1 or 2 are preferred.

  Examples of polymers having a group represented by Chemical Formula 1 and having a carboxy group-containing monomer as a copolymerization component are shown below. In the formula, the number represents the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  The polymer of the present invention may further contain another monomer as a copolymer component. Other monomers include styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene, 4-methoxystyrene, methyl methacrylate, Methacrylic acid alkyl esters such as ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and dodecyl methacrylate, aryl methacrylates or alkylaryl esters such as phenyl methacrylate and benzyl methacrylate , 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monoester methacrylate, methoxyethylene methacrylate Methacrylic acid esters having an alkyleneoxy group such as glycol monoester and methacrylic acid polypropylene glycol monoester, amino group-containing methacrylic acid esters such as 2-dimethylaminoethyl methacrylate and 2-diethylaminoethyl methacrylate, or acrylic acid esters Examples of these corresponding methacrylic acid esters, or monomers having a phosphoric acid group such as vinylphosphonic acid, amino group-containing monomers such as allylamine and diallylamine, or vinylsulfonic acid and its salts, allylsulfone Monomers having a sulfonic acid group such as acid and its salt, methallylsulfonic acid and its salt, styrenesulfonic acid and its salt, 2-acrylamido-2-methylpropanesulfonic acid and its salt As monomers having a nitrogen-containing heterocyclic ring such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, or monomers having a quaternary ammonium base, 4-vinylbenzyltrimethylammonium chloride, acryloyloxyethyl Trimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinylbenzylpyridinium chloride, or acrylonitrile, methacrylonitrile, Acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N-isopropyl acrylate Acrylamide or methacrylamide derivatives such as amide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate, chloroacetic acid Vinyl esters such as vinyl, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, and vinyl ethers such as methyl vinyl ether and butyl vinyl ether, N-vinyl pyrrolidone, acryloyl morpholine, tetrahydrofurfuryl methacrylate, vinyl chloride , Various monomers such as vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, glycidyl methacrylate, etc. And the like.

  There is a preferred range for the molecular weight of the polymer according to the present invention, and the weight average molecular weight is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 5,000 to 500,000.

  The photosensitive layer of the present invention contains a photopolymerization initiator. Known compounds can be used as the photopolymerization initiator. For example, organic boron salts, trihaloalkyl-substituted compounds (for example, s-triazine compounds and oxadiazole derivatives, trihaloalkylsulfonyl compounds as trihaloalkyl-substituted nitrogen-containing heterocyclic compounds), hexaarylbisimidazoles, titanocene compounds, ketoximes Compounds, thio compounds, organic peroxides, onium salts (iodonium salts, diazonium salts, sulfonium salts described in JP-A-2003-114532) and the like. Among these photopolymerization initiators, organic boron salts and trihaloalkyl-substituted compounds are particularly preferably used. More preferably, an organic boron salt and a trihaloalkyl-substituted compound are used in combination.

  The organic boron anion constituting the organic boron salt is represented by the following general formula.

In the formula, each of R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ may be the same or different, and represents an alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, cycloalkyl group or heterocyclic group. To express. Of these, it is particularly preferred that one of R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ is an alkyl group and the other substituent is an aryl group.

  Examples of the cation constituting the organic boron salt include alkali metal ions and onium compounds, and preferred are onium salts such as ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and triaryls. Examples thereof include phosphonium salts such as alkylphosphonium salts. Examples of particularly preferred organic boron salts are shown below.

  Other preferred photopolymerization initiators include trihaloalkyl-substituted compounds. Specifically, the trihaloalkyl-substituted compound is a compound having at least one trihaloalkyl group such as a trichloromethyl group or a tribromomethyl group in the molecule. As a preferable example, the trihaloalkyl group is a nitrogen-containing complex. Examples of the compound bonded to the ring group include s-triazine derivatives and oxadiazole derivatives, or trihaloalkylsulfonyl compounds in which the trihaloalkyl group is bonded to an aromatic ring or a nitrogen-containing heterocycle via a sulfonyl group. .

  Particularly preferred examples of trihaloalkyl-substituted nitrogen-containing heterocyclic compounds and trihaloalkylsulfonyl compounds are shown below.

  The content of the photopolymerization initiator as described above is preferably in the range of 1 to 100% by mass and more preferably in the range of 1 to 40% by mass with respect to the polymer described above.

  The photosensitive layer of the present invention contains a sensitizing dye having absorption in the near infrared of 750 nm or more. By making the photosensitive layer correspond to scanning exposure using near-infrared (750 to 1100 nm wavelength region) laser light, it is possible to handle under a bright room (under a fluorescent lamp from which ultraviolet rays are cut). Specific examples of sensitizing dyes used for sensitizing the photosensitive layer to such near infrared light are shown below.

The content of the sensitizing dye exemplified above is suitably about 3 to 300 mg per 1 m ² of the photosensitive layer. Preferably it is 10-200 mg / m < ² >.

  The photosensitive layer of the present invention preferably further contains an ethylenically unsaturated compound as a polymerizable monomer or oligomer. By combining this, a higher sensitivity can be realized, and a lithographic printing plate excellent in printing performance can be obtained.

  Examples of the ethylenically unsaturated compound according to the present invention include polymerizable compounds having two or more polymerizable double bonds in the molecule. Examples of preferred ethylenically unsaturated compounds include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trisacryloyloxyethyl isocyanurate, tripropylene Polyfunctional acrylic monomers such as glycol diacrylate, ethylene glycol glycerol triacrylate, glycerol epoxy triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate and the like can be mentioned.

  Alternatively, an oligomer having radical polymerizability is preferably used in place of the above-described polymerizable compound, and polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, etc. as various oligomers into which acryloyl group or methacryloyl group is introduced Are also used in the same manner, but these can also be preferably used as ethylenically unsaturated compounds.

  A more preferred embodiment of the ethylenically unsaturated compound is a polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule. When this compound is used, crosslinking is effectively carried out by recombination of styryl radicals generated by the generated radicals, so that it is extremely preferable for producing a highly sensitive photosensitive lithographic printing plate.

  A polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule is typically represented by the following general formula.

In the formula, Z ₂ represents a linking group, and R ₁₁ , R ₁₂ and R ₁₃ are a hydrogen atom, a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, and an aryl group. An alkoxy group, an aryloxy group, and the like, and these groups may be substituted with an alkyl group, an amino group, an aryl group, an alkenyl group, a carboxy group, a sulfo group, a hydroxy group, or the like. R ₁₄ represents a substitutable group or atom. m ₂ represents an integer of 0 to 4, and k ₂ represents an integer of 2 or more.

Further details will be described. As the linking group for Z ₂ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₁₅ ) —, —C (O) —O—, —C (R ₁₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₁₅ and R ₁₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

  Examples of the heterocyclic group include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiatriazole ring, indole ring. , Indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, quinoxaline ring, etc. A nitrogen-containing heterocyclic ring, a furan ring, a thiophene ring and the like, and a substituent may be bonded to these.

Among the compounds represented by the formula 19, there are preferable compounds. That is, R ₁₁ and R ₁₂ are hydrogen atoms, R ₁₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and k ₂ is preferably a compound having 2-10. Specific examples of the compound represented by Chemical Formula 19 are shown below, but are not limited to these examples.

  There is a preferred range for the proportion of the ethylenically unsaturated compound as described above in the photosensitive layer of the photosensitive lithographic printing plate, and the ethylenically unsaturated compound is from 1 part by mass to 60 parts in a total of 100 parts by mass of the photosensitive layer. It is preferably contained in the range of 5 parts by mass, more preferably in the range of 5 to 50 parts by mass.

  In the photosensitive layer of the present invention, other components may be preferably added for various purposes in addition to the components described above. For example, for the purpose of improving the storage stability, it is preferable to add a hindered phenol compound or a hindered amine compound. The addition amount of these compounds is preferably used in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymer.

  A polymerization inhibitor can be preferably added as another element constituting the photosensitive layer of the present invention. For example, compounds such as quinone and phenol are preferably used, and compounds such as hydroquinone, p-methoxyphenol, catechol, t-butylcatechol, 2-naphthol, and 2,6-di-t-butyl-p-cresol are used. Preferably used. The preferred proportion of these polymerization inhibitors and the aforementioned ethylenically unsaturated compounds is preferably used in the range of 0.001 to 0.1 parts by mass with respect to parts by mass of the ethylenically unsaturated compounds.

  The elements constituting the photosensitive layer of the present invention may contain other elements in addition to the above elements for various purposes. For example, inorganic fine particles or organic fine particles are also preferably added for the purpose of preventing blocking or improving the sharpness of an image after development.

  Regarding the thickness of the photosensitive layer itself of the negative planographic printing plate of the present invention, it is preferable to form it on the support with a dry thickness in the range of 0.5 μm to 10 μm, and further in the range of 1 μm to 5 μm. It is extremely preferable for greatly improving the performance. The photosensitive layer is coated and dried on the support using various known coating methods.

  Examples of the coating method include roll coating, dip coating, air knife coating, gravure coating, hopper coating, blade coating, and wire doctor coating.

  Next, the plate making process of the negative planographic printing plate of the present invention will be described. The plate-making treatment is subjected to development, washing and finishing after exposure, but usually the development, washing and finishing are continuously performed in one processing apparatus, and the plate-making is completed through a drying step.

  As the developer of the present invention, any aqueous alkaline solution can be used as long as the pH is 9 or more. Examples of the alkali agent include sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide, sodium borate, potassium borate, ammonium borate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, Inorganic alkaline agents such as potassium carbonate, ammonium carbonate, dibasic sodium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, trisodium phosphate, tribasic potassium phosphate and tribasic ammonium phosphate, monomethylamine , Dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine , Monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-ethylethanolimine, Nn-butylethanolamine, Nt-butylethanolamine, Nn-butyldiethanolamine, Nt-butyldiethanolamine N-methylethanolamine, N-methyldiethanolamine, N-aminoethylethanolamine, N-aminoethylpropanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Examples include organic alkali agents, alkali metal silicates such as sodium silicate, potassium silicate and lithium silicate, and ammonium silicate. These can be used alone or in combination of two or more.

  A preferred embodiment of the present invention is a developer having a pH of less than 12 formed by combining one or two of an inorganic alkali agent and an organic alkali agent without containing silicate. More preferably, it is a developer having a pH of 10 or more and less than 12.

  The developer used in the present invention can be used in combination with other various surfactants, and examples thereof include anionic, cationic, nonionic and amphoteric surfactants. These surfactants used in combination are added to the developer in the range of 0.001 to 10% by mass, more preferably 0.01 to 5% by mass.

  Various development stabilizers can be used in the developer used in the present invention. Preferred examples thereof include polyethylene glycol adducts of sugar alcohols described in JP-A-6-282079, phosphonium salts such as tetrabutylphosphonium bromide, and iodonium salts such as diphenyliodonium chloride. Furthermore, anionic surfactants or amphoteric surfactants described in JP-A-50-51324, water-soluble cationic polymers described in JP-A-55-95946, and JP-A-56-142528 are described. There are water-soluble amphoteric polyelectrolytes that have been described. Further, an organic boron compound to which an alkylene glycol is added as described in JP-A No. 59-84241, a polyethylene glycol having a weight average molecular weight of 300 or more as described in JP-A No. 61-215554, and a cation as described in JP-A No. 63-175858. And a fluorine-containing surfactant having a functional group, a water-soluble ethylene oxide adduct obtained by adding 4 mol or more of an acid or an alcohol or an alcohol disclosed in JP-A-2-39157, and a water-soluble polyalkylene compound.

  In the processing method of the present invention, after exposure, processing is usually performed by an automatic developing machine. The automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for transporting the printing plate, each processing liquid tank and a spray tank, and is assembled by a pump while horizontally transporting the exposed printing plate. Each processing solution is sprayed from a spray nozzle to develop and post-process. Recently, a developing method has been developed in which a printing plate is dipped and conveyed by a submerged guide roll in a developing tank filled with a developing solution, and such a developing method can also be suitably applied to the present invention. . Such an automatic developer can be processed while replenishing the replenisher according to the development processing amount, operating time, and the like.

  The printing plate developed with the developer having such a composition is subjected to post-processing with a washing water, a rinse solution containing a surfactant, a finisher mainly composed of gum arabic or starch derivatives, or a protective gum solution. The In the post-treatment of the printing plate of the present invention, these treatments can be used in various combinations. For example, development → water washing → rinsing liquid treatment containing surfactant or development → water washing → finisher liquid treatment is a rinse liquid or finisher. Less liquid fatigue is preferable. Furthermore, a countercurrent multistage process using a rinse liquid or a finisher liquid is also a preferred embodiment. These post-processing are generally performed using an automatic developing machine including a developing unit and a post-processing unit. As the post-treatment liquid, a method of spraying from a spray nozzle or a method of conveying through a treatment tank filled with the treatment liquid is used. A method is also known in which a small amount of aqueous water is supplied to the plate surface after development and washed with water, and the waste solution is reused as dilution water for the developer stock solution. In such automatic processing, each processing solution can be processed while being replenished with the respective replenishing solution according to the processing amount and operating time. In addition, a so-called disposable processing method in which treatment is performed with a substantially unused post-treatment liquid can also be applied. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
<Aluminum support>
An aluminum plate having a thickness of 0.24 mm subjected to graining and anodizing treatment was treated with the following treatment solution <Invention 1> containing potassium silicate, potassium hydroxide, and a styrene / maleic anhydride copolymer as an alkali-soluble polymer. Using a treatment liquid <Invention 2> containing a carboxyl group-containing styrene-butadiene copolymer, a silicate treatment was carried out at 55 ° C. for 7 seconds and dried to obtain an aluminum support. Further, as a comparison, the treatment liquid <Comparative Example 1> containing no alkali-soluble polymer and the treatment liquid <Comparative Example 2> containing no alkali silicate were treated under the same conditions and dried to obtain an aluminum support. It was.

<The treatment liquid of the present invention 1>
48% by mass KOH 40g
20% by weight potassium silicate 75g
10g of styrene / maleic anhydride copolymer
Ratio (40:60)
1L with water
<The treatment liquid of the present invention 2>
48% by mass KOH 40g
20% by weight potassium silicate 75g
Styrene / methacrylic acid copolymer 10g
Ratio (40:60)
1L with water
<Processing liquid of Comparative Example 1>
48% by mass KOH 40g
20% by weight potassium silicate 75g
1L with water
<Processing liquid of Comparative Example 2>
48% by mass KOH 40g
10g of styrene / maleic anhydride copolymer
1L with water

  Further, Comparative Example 3 was treated with the treatment liquid of Comparative Example 1 and then with polyvinyl sulfonic acid. Further, Comparative Example 4 was treated with only polyvinyl sulfonic acid, and Comparative Example 5 was treated without any treatment.

<Preparation of photosensitive lithographic printing plate>
A coating solution of the following photosensitive composition is applied on the above aluminum support so that the dry thickness is 2.6 microns, and is dried in a drier at 75 ° C. for 7 minutes. A lithographic printing plate was prepared.
<Coating liquid for photosensitive composition>
Polymer (P-1; mass average molecular weight of about 90,000) 10 parts by mass Photopolymerization initiator (BC-5) 2 parts by mass
(BS-1) 1 part by weight Ethylenically unsaturated compound (C-1) 5 parts by weight Sensitizing dye (S-33) 0.3 part by weight Polymerization inhibitor 2,6-di-t-butylcresol 0.1 Part by mass Solvent 1,3-dioxolane 70 parts by mass
20 parts by mass of cyclohexanone
Carbon black with an average particle size of 185 nm
0.1% by mass of 25% methyl ethyl ketone solution

Using the lithographic printing plate produced as described above, a thermal output machine (Dainippon Screen Mfg. Co., Ltd. Image Setter PT-R4000 (oscillation wavelength 830 nm, output 100 mW)) was used for each sample. After the exposure, using a processor PD-912-M (Dainippon Screen Mfg. Co., Ltd.), the developer of the following formulation is treated at 28 ° C. for 20 seconds, and then the gum solution of the following formulation is applied. did.
<Developer>
N-ethylethanolamine 37g
Phosphoric acid (85% solution) 10g
60g tetramethylammonium hydroxide (25% solution)
Alkyl naphthalenesulfonic acid Na (35% solution) 30 g
Diethylenetriaminepentaacetic acid 1g
1L with water
pH is 11.3 (25 ° C)
<Gum solution>
Phosphoric acid 1 potassium 20g
Gum arabic 30g
Sodium dehydroacetate 0.5g
EDTA2Na 1g
1L with water

The printing performance of the planographic printing plate prepared as described above was evaluated. The results are shown in Table 1.
<Press life>
Printing machine Heidelberg KORD (trademark of offset printing machine manufactured by Heidelberg), ink (New Champion ink H manufactured by Dainippon Ink & Chemicals, Inc.) and commercially available PS plate moisturizer (ASTROMARK III Nikken Chemical Co., Ltd.) )), And the number of printed sheets when printing was impossible due to either poor ink loading or line skipping was evaluated according to the following criteria.
○: 100,000 or more △: 50,000 to 90,000 ×: less than 50,000

<Soil dirt>
Printing machine Heidelberg KORD (trademark of offset printing machine manufactured by Heidelberg), ink (HYECOO red (M) manufactured by Toyo Ink Mfg. Co., Ltd.) and commercially available PS plate moisturizer (ASTROMARK III Nikken Chemical Co., Ltd.) The product was printed up to 20,000 sheets, and the background stain on the non-image area was evaluated according to the following criteria.
○: No contamination at 20,000 sheets.
Δ: Dirt is generated after 10,000 sheets.
X: Dirt is generated on 2,000 sheets.

<The halftone dot shade network>
Printing machine Heidelberg KORD (trademark of offset printing machine manufactured by Heidelberg), ink (New Champion Purple S manufactured by Dainippon Ink & Chemicals, Inc.) and commercially available PS plate moisturizer (ASTROMARK III Nikken Chemical Co., Ltd.) )) Is used to print 1000 sheets at the start of ink removal (supplying only the ink to the plate and then supplying the moisturizing liquid), and 90% of the dots of the printed material are tangled and become solid. Whether or not it was evaluated according to the following criteria.
○: Halftone dots are not entangled at all.
Δ: The halftone dots are slightly tangled.
X: The halftone dots are solid.

  From the above results, the negative lithographic printing plate treated with the treatment liquid containing the alkali metal silicate of the present invention and the alkali-soluble polymer compared to the comparative example has no effect on printing durability, and has a background stain and a halftone dot shadow portion. It can be seen that there is no blur in the screen.

Claims (3)

  A negative lithographic printing plate comprising a photopolymerizable photosensitive layer on an aluminum support obtained by treating an anodized aluminum plate with a treatment solution containing an alkali metal silicate and an alkali-soluble polymer. .   The negative lithographic printing plate according to claim 1, wherein the photosensitive layer contains a polymer having an ethylenically unsaturated double bond in a side chain and a carboxyl group-containing monomer as a copolymerization component.   The negative lithographic printing plate according to claim 1, wherein the photosensitive layer contains an organic boron salt and a dye having absorption in a wavelength region of 750 nm or more.