JP2008250197A - Negative photosensitive planographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative photosensitive composition having high sensitivity, excellent white light safeness, excellent dot reproducibility in FM screen printing, and excellent small dot plate wear for small dots. <P>SOLUTION: A negative photosensitive planographic printing plate is characterized in that a photosensitive layer disposed on a support contains a photo-radical generator, a sensitizer showing absorption in a wavelength region from visible light to IR light and sensitizing the photo-radical generator, a compound having an ethylenic double bond, and a salt of an inorganic acid or an organic acid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photopolymerizable negative photosensitive lithographic printing plate. More specifically, the present invention relates to a negative photosensitive lithographic printing plate for so-called direct plate making that can be directly made from a digital signal from a computer or the like.

  In recent years, computer-to-plate (CTP) technology has been developed to output directly on a printing plate based on digital data created on a computer, and various plate setters equipped with various lasers as output machines and their corresponding photosensitivity. Planographic printing plates are being actively developed. In particular, with the remarkable progress of semiconductor lasers in recent years, it has become possible to easily use an infrared laser light source, and a photosensitive material and a photosensitive lithographic printing plate corresponding to the laser beam have attracted particular attention. For example, as a photopolymerizable composition having photosensitivity from visible light to near infrared light, JP-A-9-134007 discloses a radical polymerizable compound having an ethylenically unsaturated bond and an absorption peak at 400 to 500 nm. A lithographic printing plate material containing a photosensitizer and a photoradical generator is disclosed. JP-A-62-143044, JP-A-62-1050242, JP-A-5-5988, JP-A-5-194619, JP-A-5-197069, JP-A-2000-98603, etc. disclose a combination of a photo radical generator and a sensitizer. In JP-A-2001-290271 (Patent Document 1), in a photosensitive system in which a specific polymer, a photo radical generator, and a sensitizer are present, a high sensitivity can be obtained by adding a specific monomer. A method for producing a negative type printing plate is disclosed. However, in photopolymerizable negative lithographic printing plates combining a sensitizer and a photoradical generator, the reaction is easy to diffuse to the peripheral area of the image area because of its high sensitivity, and a high halftone dot. It was difficult to achieve reproducibility. In addition, from the viewpoint of workability, it is desirable that such a photosensitive lithographic printing plate can be handled under white light. However, since the crosslinking reaction proceeds due to radicals generated by white light irradiation and the elution failure occurs, the printed matter is soiled. There was a problem of becoming.

  As means for improving the safety of white light, JP 2005-92040 A (Patent Document 2) discloses a photosensitive lithographic printing plate provided with an overlayer containing an ultraviolet absorber and polyvinyl alcohol. However, this method has a drawback in that the laser beam is scattered in the overlayer, and the halftone dot reproducibility is lowered. Japanese Patent Laid-Open No. 2000-10281 discloses a lithographic printing plate that uses a specific fluorine-based polymer compound, but does not have sufficient printing durability.

The printing market is diversifying, and the demand for high-definition printing using FM screens is increasing. In Japanese Patent Laid-Open No. 2001-324798 (Patent Document 3), a high-definition image of a crosslinked negative lithographic printing plate can be drawn with a two-layer structure in which a photosensitive layer is present on an alkali-soluble layer. However, it was not satisfactory in terms of small dot printing durability and white light safety. In Japanese Patent Application Laid-Open No. 2006-309145 (Patent Document 4), the halftone dot reproducibility is improved by containing a specific polymer compound in the photosensitive layer, but with regard to small dot printing durability and white light safety, The required performance was not met. Therefore, even in high-definition printing such as FM screen printing, it is difficult to obtain excellent white light safety, halftone dot reproducibility and small dot printing durability at the same time, and a product with sufficient performance can be obtained. Not.
JP 2001-290271 A JP 2005-92040 A JP 2001-324798 A JP 2006-309145 A

  Accordingly, an object of the present invention is to provide a photopolymerizable negative having excellent white light safety and at the same time excellent dot reproducibility in high-definition printing such as FM screen printing and excellent small dot printing durability. Is to provide a type photosensitive lithographic printing plate.

(1) A photosensitive layer provided on a support has a photoradical generator, a sensitizer having absorption in a wavelength region from visible light to infrared light, and sensitizing the photoradical generator, an ethylenic double A negative photosensitive lithographic printing plate comprising a compound having a bond and a salt of an amine and an inorganic acid or an organic acid.
(2) The negative according to (1), wherein the salt of the amine and the inorganic acid or organic acid contained in the photosensitive layer is a salt of a tertiary amine and an inorganic acid having a pKa of 2.7 or less. Type photosensitive lithographic printing plate.

  Provided is a negative photosensitive lithographic printing plate which is excellent in white light safety while having high sensitivity by the above means and excellent in halftone dot reproducibility and small dot printing durability in high definition printing such as FM screen printing. Can do.

  Hereinafter, the present invention will be described in detail. The negative photosensitive lithographic printing plate of the present invention contains an amine and a salt of an inorganic acid or an organic acid (hereinafter referred to as the compound of the present invention) in the photosensitive layer. The compound of the present invention is specifically a compound having the following unit structure in the molecule.

In the unit structure 1, R ₁ and R ₂ each represent a hydrogen atom, an alkyl group, an aryl group, a hydroxy, an alkoxy group, or an amino group, and these groups further include an alkyl group, an aryl group, an alkenyl group, an alkoxy group, It may be substituted with a carboxyl group, a hydroxy group, a halogen atom, a sulfo group, a nitro group, a cyano group, an amide group, a hydroxy group, or the like. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an isobutyl group, an isopentyl group, a sec-butyl group, a tert-butyl group, and a cyclohexyl group, and an aryl group. Examples thereof include a phenyl group and a naphthyl group. Examples of the alkenyl group include a vinyl group, an allyl group, and a propargyl group. Examples of the alkoxy group include a methoxy group and an ethoxy group. Examples of the aryloxy group include a phenoxy group. A naphthoxy group, and the acyl group includes a substituent such as a formyl group, an acetyl group, a propionyl group, and a benzoyl group. In the unit structure 1, a cyclic structure may be formed by R ₁ and R ₂ . In the unit structure 2, R ₃ has the same meaning as R ₁ and R _{2 in} the unit structure 1, and Z ₁ is a five-membered ring or a six-membered ring composed of atoms arbitrarily selected from carbon, oxygen, nitrogen, sulfur and selenium atoms. It represents a membered nitrogen-containing heterocycle, and this heterocycle can be modified with a substituent or condensed with another ring. Examples of the nitrogen-containing heterocycle include a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, and a selenazole ring.

  In addition, the compound of the present invention may contain a plurality of the above unit structures 1 and 2 via an appropriate linking group in the molecule, and may contain 1 to 3 of the above unit structures 1 and 2. preferable.

X ₁ described in the unit structures 1 and 2 represents an anion of an organic acid or an inorganic acid. As an anion of inorganic acid, sulfuric acid (pKa = −5.0), phosphoric acid (pKa = 2.2), nitric acid (pKa = −1.3), hydrochloric acid (pKa = −8.0), hydrogen bromide Acid (pKa = -4.7), hydroiodic acid (pKa = -5.2), nitrous acid (pKa = 3.2), chlorous acid (pKa = 2.3), hypochlorous acid (pKa) And oxoacids composed of halogen group elements such as 7.5). As anions of organic acids, formic acid (pKa = 3.6), acetic acid (pKa = 4.6), butyric acid (pKa = 4.6), valeric acid (pKa = 4.6), caproic acid (pKa = 4.6), enanthic acid (pKa = 4.7), caprylic acid (pKa = 4.9), isobutyric acid (pKa = 4.6) monofluoroacetic acid (pKa = 2.6), pyrpinic acid (pKa = 2.3), lactic acid (pKa = 3.7), citric acid (pKa = 2.9), malic acid (pKa = 3.2), succinic acid (pKa = 4.0), malonic acid (pKa = 2) 7), fumaric acid (pKa = 2.9), maleic acid (pKa = 1.8), benzoic acid (pKa = 4.2), phthalic acid (pKa = 4.5), salicylic acid (pKa = 2. 8), an acid anion of cinnamic acid (pKa = 3.9).

  Of these, salts of tertiary amines and inorganic acids or organic acids are preferable, tertiary amines and inorganic salts, and tertiary amines and salts of inorganic acids having a pKa of 2.7 or less are more preferable.

  Although the compound of this invention is shown below, it is not limited to the following example.

  The detailed mechanism of action of the compound of the present invention is unclear, and the mechanism of action described below is beyond the scope of speculation. However, the above compound of the present invention plays a role in promoting degeneration of the generated radicals. Conceivable. A photopolymerizable negative lithographic printing plate comprising a photoradical generator and a sensitizer that absorbs in the wavelength region from visible light to infrared light and sensitizes the photoradical generator in a photosensitive layer. Because of its sensitivity, it is exposed to light from a white light when handling the negative lithographic printing plate, and generates radicals when handling the negative lithographic printing plate. A residual film is formed in the non-image area. In light of low illuminance such as a white light, the amount of radicals generated is small, so the above-mentioned compound of the present invention causes a large amount of radicals and is considered to reflect the improvement of white light safety. In addition, even when the reaction diffuses around the image area, the reaction can be stopped more quickly due to the radical decapitation effect of the compound of the present invention, so that good halftone dot reproducibility can be obtained in FM screen printing and the like. Can be achieved. In the image area exposed at high illuminance, a large amount of radicals are generated by the photoradical generator present in the system. Therefore, even if some radicals are lost by the compound of the present invention, FM It is considered that there is no effect on the small dot printing durability in screen printing or the like.

  In the present invention, the content of the compound of the present invention is preferably 0.003 to 7% by mass with respect to the compound having an ethylenic double bond described later, and is preferably 0.005 to 5% by mass. It is more preferable to contain in the range, and the range of 0.01 to 2 mass% is particularly preferable. Moreover, it is preferable that the sum total of the number of the carbon atoms which comprise the compound of this invention is 10 or less.

  The photosensitive layer of the present invention contains a photo radical generator. A known compound can be used as the photoradical generator. For example, organic boron salts, trihaloalkyl-substituted compounds (for example, s-triazine compounds and oxadiazole derivatives as trihaloalkyl-substituted nitrogen-containing heterocyclic compounds, trihaloalkylsulfonyl compounds), hexaarylbisimidazoles, titanocene compounds, ketoximes Examples thereof include compounds, thio compounds, and organic peroxides. Among these photoradical generators, 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 ₄ , R ₅ , R ₆ and R ₇ 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 ₄ , R ₅ , R ₆ and R ₇ 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 photoradical generators 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 photo radical generator 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 compound having an ethylenic double bond described later. Is preferred.

  The photosensitive layer of the present invention has an absorption in the wavelength region from visible light to near infrared light so as to be compatible with various light sources from visible light to near infrared light, and sensitizes the aforementioned photo radical generator. Contains a sensitizer. As the sensitizer, various sensitizing dyes are preferably used. Such sensitizing dyes include cyanine, phthalocyanine, merocyanine, coumarin, porphyrin, spiro compound, ferrocene, fluorene, fulgide, imidazole, perylene, phenazine, phenothiazine, polyene, azo compound, diphenylmethane, triphenylmethane, polymethine acridine, coumarin. Ketocoumarin, quinacridone, indigo, styryl, squarylium compound, pyrylium compound, and further described in European Patent No. 0,568,993, US Patent Nos. 4,508,811, and 5,227,227. These compounds can also be used.

  The photosensitive lithographic printing plate of the present invention preferably contains a sensitizing dye having absorption in near infrared light of 750 nm or more so as to correspond to a near infrared laser. By making the photosensitive layer correspond to a wavelength region of near infrared to infrared light (a wavelength region of 750 to 1100 nm), 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.

In recent years, output machines equipped with a blue semiconductor laser having an oscillation wavelength of 400 to 430 nm have become widespread. This output machine has a maximum exposure energy amount of about several tens of μJ / cm ² , and the photosensitive material used is required to have high sensitivity. As a sensitizer for dealing with a blue semiconductor laser, a pyrylium compound or a thiopyrylium compound is preferable.

In the present invention, the content of the sensitizer is suitably about 3 to 300 mg per 1 m ² of the photosensitive layer of the photosensitive lithographic printing plate. Preferably it is 10-200 mg / m < ² >.

  The photosensitive layer of the present invention contains at least a compound having an ethylenic double bond. Examples of the compound having an ethylenic double bond include a polymer and a monomer having an ethylenic double bond, but a polymer having an ethylenic double bond in the side chain because of excellent dot-point printing durability. Is particularly preferred. Such ethylenic double bonds include vinyl groups, allyl groups, and phenyl groups substituted with vinyl groups. In particular, a polymer having a phenyl group in which a vinyl group is substituted on the side chain is preferable because of high sensitivity and excellent printing durability.

  Examples of the monomer having a vinyl group and an allyl group include vinyl (meth) acrylate, vinyl (meth) acrylamide, allyl (meth) acrylate, allyl (meth) acrylamide and the like, and homopolymers or copolymers using these. Examples of the polymer.

  The polymer having a phenyl group in which vinyl is substituted on the side chain is a polymer having a group represented by the following general formula in the side chain.

In the formula, Z ₂ represents a linking group, and R ₈ , R ₉ , and R ₁₀ 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 ₁₁ represents a group or an atom that can be substituted with a hydrogen atom. n represents 0 or 1, m ₁ represents an integer of 0 to 4, and k ₁ represents an integer of ₁ to 4.

The group represented by the above general formula will be described in more detail. As the linking group for Z ₂ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₁₂ ) —, —C (O) —O—, —C (R ₁₃ ) ═N—, Examples include -C (O)-, a sulfonyl group, a heterocyclic group, and a group represented by the following, alone or in combination of two or more. Here, R ₁₂ and R ₁₃ 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. Examples of groups represented by the above general formula are shown below, but are not limited to these examples.

Among the groups represented by the above general formula, there are preferable ones. That is, it is preferable that R ₈ and R ₉ are hydrogen atoms and R ₁₀ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.). Further, as the linking group Z ₂ , those containing a heterocyclic ring are preferred, and those in which k ₁ is 1 or 2 are preferred.

  In addition, the polymer having an ethylenic double bond in the side chain is preferably soluble in an alkaline aqueous solution, and for that purpose, a polymer containing a carboxyl group-containing monomer as a copolymerization component is particularly preferable. In this case, the proportion of the monomer having an ethylenic double bond in the side chain as described above in the copolymer composition is preferably 1% by mass or more and 95% by mass or less in 100% by mass of the total composition. The range of 5-95 mass% is more preferable, and the range of 10-90 mass% is more preferable. Similarly, the proportion of the carboxyl group-containing monomer in the copolymer is preferably 5% by mass or more and 99% by mass or less, and more preferably in the range of 10 to 90% by mass. If the ratio is less than this, the copolymer may not be dissolved in the alkaline aqueous solution.

  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 Examples include monoalkyl esters, 4-carboxystyrene and the like.

  The polymer used in the present invention is synthesized as a multi-component copolymer by introducing other monomer components into the copolymer in addition to the monomer having an ethylenic double bond in the side chain and the monomer having a carboxyl group. , It can also be preferably used. As monomers that can be incorporated into the copolymer in such a case, styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-aminostyrene, chloromethylstyrene, 4-methoxystyrene, Methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, aryl methacrylates such as phenyl methacrylate and benzyl methacrylate Esters or alkylaryl esters, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monoester methacrylate, methacrylate Methacrylic acid esters having an alkyleneoxy group such as acid methoxypolyethylene glycol monoester and methacrylic acid polypropylene glycol monoester, amino group-containing methacrylic acid esters such as 2-dimethylaminoethyl methacrylate and 2-diethylaminoethyl methacrylate, Alternatively, examples similar to these corresponding methacrylic acid esters as acrylic acid esters, vinylphosphonic acid or the like as a monomer having a phosphoric acid group, amino group-containing monomers such as allylamine or diallylamine, or vinylsulfonic acid and its Sulfos such as salts, allyl sulfonic acid and its salts, methallyl sulfonic acid and its salts, styrene sulfonic acid and its salts, 2-acrylamido-2-methylpropane sulfonic acid and its salts Monomers having an acid group, monomers having a nitrogen-containing heterocycle such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, or 4-vinylbenzyl as a monomer having a quaternary ammonium base Trimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinylbenzylpyridinium chloride, etc. Or acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N Acrylamide or methacrylamide derivatives such as isopropyl acrylamide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate, Vinyl esters such as vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, etc., and vinyl ethers such as methyl vinyl ether, butyl vinyl ether, others, N-vinyl pyrrolidone, acryloylmorpholine, tetrahydrofurfuryl methacrylate, Vinyl chloride, vinylidene chloride, allyl alcohol, vinyl trimethoxysilane, glycidyl meta Can be used Relate such various monomers as arbitrary copolymerization monomers. The proportion of these monomers in the copolymer is arbitrary as long as the preferred proportion of the group and carboxyl group-containing monomer represented by the above general formula in the copolymer composition described above is maintained. Can be introduced at a rate of.

  The molecular weight of the polymer used in the present invention is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 10,000 to 300,000 in terms of mass average molecular weight.

  Examples of polymers having a phenyl group substituted with vinyl in the side chain according to the present invention are shown below. In the formula, the number represents the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  The monomer having an ethylenic double bond is preferably a monomer having two or more ethylenic double bonds, and the molecular weight of the compound is 10,000 or less, preferably 5,000 or less. Examples of the monomer include compounds having two or more ethylenic double bonds such as an acryloyl group, a methacryloyl group, and a phenyl group substituted with a vinyl group.

  Examples of the compound having an acryloyl group or a methacryloyl group as an ethylenic double bond include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol di (meth) acrylate. , Tetraethylene glycol di (meth) acrylate, trisacryloyloxyethyl isocyanurate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, pentaerythritol tri (meth) Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipe Data erythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pyrogallol triacrylate.

  A monomer having a phenyl group substituted with a vinyl group as an ethylenic double bond is typically represented by the following general formula.

In the formula, Z ₃ represents a linking group, and R ₁₄ , R ₁₅ and R ₁₆ 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 ₁₇ 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.

The above general formula will be described in more detail. As the linking group for Z ₃ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₁₈ ) —, —C (O) —O—, —C (R ₁₉ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₁₈ and R ₁₉ 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 monomers represented by the above general formula, there are preferable monomers. That is, R ₁₄ and R ₁₅ are hydrogen atoms, R ₁₆ 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. Although a specific example is shown below, it is not limited to these examples.

  The content of the monomer as described above is preferably in the range of 1 to 100% by mass and more preferably in the range of 5 to 50% by mass with respect to the polymer having an ethylenic double bond.

  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, it is preferable to add various polymerization inhibitors for the purpose of improving storage stability. As the polymerization inhibitor in this case, compounds having various phenolic hydroxyl groups such as hydroquinones, catechols, naphthols, and cresols, quinone compounds, and the like are preferably used, and hydroquinone is particularly preferably used. In this case, the polymerization inhibitor is preferably added in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymer. In addition, it is also preferable to add various dyes and pigments for the purpose of enhancing the visibility of the image, and to add inorganic fine particles or organic fine particles for the purpose of preventing blocking of the photosensitive composition.

  As the support of the negative photosensitive lithographic printing plate of the present invention, a support having a surface subjected to a hydrophilic treatment is used for the purpose of improving the adhesion to the photosensitive layer and providing water retention to the non-image area. It is preferable. As such a hydrophilic treatment, for example, in a plastic film support represented by polyethylene terephthalate, polyethylene naphthalate, etc., chemical treatment, discharge treatment, glow discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, active plasma treatment, Surface treatment such as laser treatment, and a hydrophilic layer described in JP-A-49-2286, JP-B-56-2983, JP-A-48-83902, JP-A-8-184967 and the like are coated. Methods and the like. As the support for the negative photosensitive lithographic printing plate of the present invention, an aluminum support is particularly preferably used. The thickness of the aluminum support used in the present invention is about 0.1 to 0.6 mm. This thickness can be changed as appropriate according to the size of the printing press, the size of the printing plate, and the desire of the user.

  The aluminum support is usually grained to a more preferred shape. Examples of the graining method include mechanical graining (mechanical surface roughening), chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. In addition, electrochemical graining (electrochemical roughening, electrolytic graining), which is electrochemically grained in hydrochloric acid electrolyte or nitric acid electrolyte, or the aluminum surface is scratched with metal wire Mechanical graining methods (mechanical roughening treatment) such as brush grain method, ball grain method to grain the aluminum surface with abrasive balls and abrasives, brush grain method to grain the surface with nylon brush and abrasives, etc. Can be used. These graining methods can be used alone or in combination. For example, a combination of a mechanical surface roughening treatment with a nylon brush and an abrasive and an electrolytic surface roughening treatment with a hydrochloric acid electrolytic solution or a nitric acid electrolytic solution, or a combination of a plurality of electrolytic surface roughening treatments may be mentioned.

  In the case of the brush grain method, the long wavelength of the surface of the aluminum support is selected by appropriately selecting the conditions such as the average particle size, maximum particle size, bristle diameter of the brush used, density, indentation pressure, etc. The average depth of the component recesses can be controlled. The recesses obtained by the brush grain method preferably have an average wavelength of 3 to 15 μm and an average depth of 0.3 to 1 μm.

As the electrochemical surface roughening method, an electrochemical method in which graining is chemically performed in a hydrochloric acid electrolytic solution or a nitric acid electrolytic solution is preferable. A preferable current density is 50 to 400 C / dm ² in terms of electricity at the time of anode. More specifically, for example, in an electrolytic solution containing 0.1 to 50% by mass of hydrochloric acid or nitric acid, under conditions of a temperature of 20 to 100 ° C., a time of 1 second to 30 minutes, and a current density of 100 to 400 C / dm ² . This is done using direct current or alternating current. According to the electrolytic surface-roughening treatment, it is easy to impart fine irregularities to the surface, which is suitable for improving the adhesion between the photosensitive layer and the aluminum support.

  Electrochemical roughening after mechanical roughening treatment supports crater-like or honeycomb-like pits with an average diameter of about 0.3 to 1.5 μm and an average depth of 0.05 to 0.4 μm. It can be produced on the surface of the body at an area ratio of 80 to 100%. In the case where only the electrochemical surface roughening method is performed without performing the mechanical surface roughening method, the average pit depth is preferably less than 0.3 μm. The provided pits have the effect of improving the resistance to contamination of the non-image area of the printing plate and the printing durability. In the electrolytic surface roughening treatment, an amount of electricity necessary for providing sufficient pits on the surface, that is, the product of the current and the time during which the current flows is an important condition. From the viewpoint of energy saving, it is desirable that sufficient pits can be formed with a smaller amount of electricity. The surface roughness after the roughening treatment is such that the arithmetic average roughness (Ra) measured at a cut-off value of 0.8 mm and an evaluation length of 3.0 mm in accordance with JIS B0601-1994 is 0.2-0. It is preferably 8 μm.

  The grained aluminum support is preferably subjected to a chemical etching process. As the chemical etching treatment, acid etching or alkali etching is known, and a chemical etching treatment using an alkaline solution is a particularly excellent method in terms of etching efficiency.

The alkali agent suitably used is not particularly limited, and examples thereof include caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, and lithium hydroxide. The alkaline etching treatment is preferably performed under such a condition that the dissolved amount of Al is 0.05 to 1.0 g / m ² . The other conditions are not particularly limited, but the alkali concentration is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and the alkali temperature is 20 to 100 ° C. It is preferable that it is, and it is more preferable that it is 30-50 degreeC. The alkali etching treatment is not limited to one method, and a plurality of steps can be combined. In the present invention, an alkali etching treatment can be performed after the mechanical roughening treatment and before the electrochemical roughening treatment. In this case, the dissolution amount of Al is preferably 0.05 to 30 g / m ² .

  After performing the alkali etching treatment, pickling is performed to remove dirt (smut) remaining on the surface. Examples of the acid used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid. In particular, as a method for removing smut after the electrolytic surface-roughening treatment, it is preferably brought into contact with 15 to 65 mass% sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739. A method is mentioned.

  Moreover, when performing a chemical etching process with an acidic solution, the acid used for an acidic solution is not specifically limited, For example, a sulfuric acid, nitric acid, and hydrochloric acid are mentioned. The concentration of the acidic solution is preferably 1 to 50% by mass. Moreover, it is preferable that the temperature of an acidic solution is 20-80 degreeC.

  The aluminum support treated as described above is further subjected to an anodizing treatment. The anodizing treatment can be performed by a method conventionally used in this field. Specifically, direct current or alternating current is applied to the aluminum support in an aqueous solution or non-aqueous solution of sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc., alone or in combination of two or more. An anodized film can be formed on the surface of the aluminum support.

The conditions for the anodizing treatment vary depending on the electrolyte used, and thus cannot be determined unconditionally. In general, however, the electrolyte concentration is 1 to 80% by mass, the solution temperature is −5 to 70 ° C., and the current density is 0.8. 5 to 60 a / dm ^2, voltage 1 to 100 V, is suitably an electrolysis time of 10 to 200 seconds. Among these anodizing treatments, the method of anodizing at a high current density in a sulfuric acid electrolyte solution described in British Patent 1,412,768 is particularly preferable.

In the present invention, the amount of anodized layer is preferably from 1 to 10 g / m ^2, more preferably from 1.5~7g / m ^2, particularly preferably from 2-5 g / m ² . After the roughening treatment, an alkali etching treatment can be performed before the electrochemical roughening treatment. In this case, the dissolution amount of Al is preferably 0.05 to 30 g / m ² .

  The aluminum support used in the present invention may be a substrate that has been surface-treated as described above and has an anodized film as it is. However, the adhesion to the photosensitive layer, hydrophilicity, resistance to contamination, heat insulation, etc. As necessary, the micropore enlargement treatment of the anodized film, the micropore sealing treatment, the surface hydrophilization treatment soaked in an aqueous solution containing a hydrophilic compound, etc. may be appropriately selected as necessary. Can do.

  Suitable hydrophilic compounds for the hydrophilization treatment include polyvinylphosphonic acid, compounds having a sulfonic acid group, saccharide compounds, citric acid, alkali metal silicates, potassium zirconium fluoride, phosphate / inorganic fluorine compounds, etc. Can be mentioned.

  The thickness of the photosensitive layer of the negative photosensitive lithographic printing plate of the present invention is preferably formed on the support with a dry thickness in the range of 0.5 μm to 10 μm, and more preferably in the range of 1 μm to 5 μm. This is extremely preferable for greatly improving the printability. The photosensitive layer is coated and dried on the support using various known coating methods.

  The negative photosensitive lithographic printing plate obtained by coating a photosensitive layer on the aluminum support is subjected to inspection exposure with various lasers, and the exposed portion is cross-linked to be soluble in an alkaline developer. Therefore, pattern formation of an exposed image is performed by eluting unexposed portions with an alkaline developer described later.

  Examples of alkaline compounds for adjusting the pH of the developer include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, tetraalkylammonium hydroxides such as tetramethylammonium hydroxide and tetrabutylammonium hydroxide, Examples include alkanolamines such as ethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, and N-ethylethanolamine. Of these, alkanolamines are particularly preferable. The content of alkanolamine is preferably in the range of 5 to 100 g per liter of the developing solution, particularly preferably in the range of 10 to 60 g.

  The developer preferably further contains an anionic surfactant, which further improves the dissolution property. Examples of such anionic surfactants include higher fatty acid sulfates, alkyl naphthalene sulfonates, alkyl benzene sulfonates, and dialkyl sulfosuccinates. Among these, alkyl naphthalene sulfonates are preferable. The content of the anionic surfactant is preferably in the range of 1 to 50 g per liter of the developing solution, and particularly preferably in the range of 3 to 30 g.

  Developers include buffering agents such as phosphoric acid and phosphate, chelating agents such as ethylenediaminetetraacetic acid and diethylenetetraminepentaacetic acid, ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, benzyl alcohol, etc. Various alcohols can be added. After developing with such an alkaline developer, normal gumming is preferably performed using gum arabic, dextrins, and the like.

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>
The 0.24 mm thick aluminum support that had been grained and anodized was subjected to sealing treatment with hot water at 90 ° C. for 30 seconds to obtain an aluminum support.

<Preparation of photosensitive lithographic printing plate>
The following photosensitive layer coating solution was applied onto the above aluminum support so that the dry thickness was 2.3 μm, and dried in a 75 ° C. drier for 10 minutes.
<Photosensitive layer coating solution>
Polymer (P-1; mass average molecular weight of about 90,000) 10 parts by mass photoradical generator 1 (BC-6) 2 parts by mass photoradical generator 2 (BS-1) 1 part by mass sensitizing dye (S-39) ) 0.4 parts by mass of compounds described in Table 1 10% phthalocyanine dispersion described in Table 1 below 0.5 parts by mass of dioxane 70 parts by mass of methanol 20 parts by mass

For the above lithographic printing plate, a plate setter equipped with an 830 nm semiconductor laser, a Trendsetter 800II Quantum manufactured by CREO Co., Ltd., a drum rotation speed of 360 rpm, resolution of 2400 dpi, FM screen Staccato 24, laser irradiation energy of 100 mJ / cm ² , 50% halftone dot And 2% small point exposure was performed. Thereafter, using a processor PD-912-M (manufactured by Dainippon Screen Mfg. Co., Ltd.), the following developer was used for processing at 28 ° C. for 15 seconds.
<Developer>
N-ethylethanolamine 37g
Phosphoric acid (85 mass% solution) 10g
60 g of tetramethylammonium hydroxide (25% by mass solution)
Alkyl naphthalenesulfonic acid Na (3 mass 5% solution) 30 g
Diethylenetriaminepentaacetic acid 1g
1L with water
pH adjusted to 11.3 (25 ° C)

<Reproducibility of halftone dots>
The lithographic printing plate produced as described above was subjected to measurement of the dot area ratio of 50% halftone dots with DM-620 (manufactured by Dainippon Screen Co., Ltd.). The results are shown in Table 2.

A gum solution having the following formulation was applied to the lithographic printing plate produced as described above, and a printing test was performed under the following printing conditions to evaluate the printing durability. The results are shown in Table 2.
<Gum solution>
Phosphoric acid 1 potassium 20g
Gum arabic 30g
Sodium dehydroacetate 0.5g
EDTA2Na 1g
Dilute to 1 L with water.

<Press life>
Using the printing machine Heidelberg KORD (trademark of Heidelberg's offset printing machine), BestOne black N-ink (manufactured by T & KTOKA Co., Ltd.) and a commercially available PS plate moisturizing liquid (Astro Mark III manufactured by Nikken Chemical Co., Ltd.) After printing 100,000 sheets and washing the ink with a plate preserver (manufactured by Koyo Chemical Industry Co., Ltd.), the halftone dot reproducibility change of 50% halftone dot and 2% small dot Was evaluated.
◯: 2% dot is left after printing ×: 2% dot is hardly left after printing or not at all.

<Safety of white light>
About the planographic printing plate before performing exposure and development, each sample was placed in a place where the irradiation intensity became 1000 lux under a 40 W white fluorescent lamp, and irradiation was performed for 1 hour. Then, after plate-making by the said method, the remaining film of a non-image part was evaluated.
○: No residual film in non-image area Δ: Slight residual film is confirmed in non-image area (usable level)
×: Residual film present (unusable level)

Item A in Table 2 above represents the pKa of the inorganic or organic acid utilized in the compound of the present invention.

  From the above results, the photosensitive lithographic printing plate of the present invention has good white light safety and has halftone dot reproducibility and small dot printing durability in FM screen printing, compared to the comparative example not containing the compound of the present invention. Excellent results were obtained. The present invention 1 containing a salt of ammonia and an inorganic acid, the present invention 2 containing a salt of a primary amine and an inorganic acid, and the present invention 3 containing a salt of a secondary amine and an inorganic acid, respectively. It was confirmed that the halftone dot reproducibility was improved with respect to Comparative Examples 1 to 3 which were not contained. Furthermore, the present invention 4, the present invention 6 containing a tertiary amine of the general formula 1 and a salt of an inorganic acid, and the present invention 5 containing a tertiary amine of the general formula 2 and a salt of an inorganic acid, The halftone dot reproducibility was even better than 3. On the other hand, the present invention 7, which contains a tertiary amine and a salt of an inorganic acid having a pKa of 2.7 or more, as compared with the present invention 9 containing a salt of an organic acid having a tertiary amine and a pKa of 2.7 or less. Invention 8 has better halftone dot reproducibility, and the present invention 4, this invention 5, and this invention 6, which contain a tertiary amine and a salt of an inorganic acid having a pKa of 2.7 or less, further provide halftone dot reproducibility. Became good. Further, in contrast to the present invention 10 in which the number of carbon atoms constituting the molecule is 10 or more, the present inventions 1 to 9 resulted in better white light safety. In addition, Comparative Example 2 in which an inorganic salt was added, Comparative Example 3 in which a tertiary aliphatic amine triethylamine was added, or Comparative Example 4 in which an inorganic salt and triethylamine were used in combination had no effect of improving the dot reproducibility. Also, good printing durability was not obtained.

Claims (2)

  The photosensitive layer provided on the support has a photoradical generator, a sensitizer that absorbs in the wavelength region of visible light to infrared light, and sensitizes the photoradical generator, and has an ethylenic double bond. A negative photosensitive lithographic printing plate comprising a compound and a salt of an amine and an inorganic or organic acid.   The negative photosensitive resin according to claim 1, wherein the salt of the amine and the inorganic acid or organic acid contained in the photosensitive layer is a salt of a tertiary amine and an inorganic acid having a pKa of 2.7 or less. Lithographic printing plate.