JP4679410B2 - Development method for photosensitive lithographic printing plate - Google Patents

Description

  The present invention mainly relates to a method for developing a photosensitive lithographic printing plate for scanning exposure in which an image is formed using various lasers. In particular, the present invention relates to a development processing method for a negative photosensitive lithographic printing plate having sensitivity to light in the near infrared to infrared wavelength range of 750 nm or more.

  A negative photosensitive lithographic printing plate that has been widely used in the past has a photosensitive coating (photosensitive layer) coated on an aluminum support. In this coating film, the exposed portion (exposed portion) is cured, and the unexposed portion (unexposed portion) is eluted by a development process. The cured portion remains as an image portion and accepts ink at the time of printing, while the eluted portion is exposed by exposing the hydrophilic aluminum surface and receiving water (dampening water) at the time of printing.

  In recent years, with the advance of image forming technology, photosensitive lithographic printing plates exhibiting high sensitivity to visible light have been demanded. For example, research on a photosensitive lithographic printing plate corresponding to an output machine using an argon laser, a helium / neon laser, a red LED, or the like has been actively conducted.

  Furthermore, with the remarkable progress of semiconductor lasers, a near-infrared laser light source of 750 to 1300 nm can be easily used, and photosensitive lithographic printing plates corresponding to the laser light have attracted attention.

  Examples of photosensitive lithographic printing plates that utilize photopolymerization and are compatible with near-infrared lasers include, for example, JP-A-8-114916, JP-A-2000-122273, JP-A-2002-278080, and JP-A-2002-283752. No., JP-A No. 2002-241547, JP-A No. 2004-126031, and the like.

  A generally known negative photosensitive lithographic printing plate utilizing photopolymerization utilizes a photopolymerization reaction of a monomer or polymer having an acrylate polymerizable double bond. In such an acrylate-based polymerization reaction, the presence of oxygen during exposure significantly inhibits the polymerization reaction due to exposure and makes it impossible to form a sufficient image. To prevent this, in order to increase the oxygen barrier property on the upper part of the photosensitive layer, Usually, an oxygen barrier layer (overlayer) made of a water-soluble resin such as polyvinyl alcohol or polyvinylpyrrolidone is provided. For example, they are described in JP-A-8-137096, JP-A-9-160226, JP-A-9-236911, JP-A-2001-166488, and the like. The photosensitive lithographic printing plate for near-infrared laser described in the above-mentioned patent document is similarly provided with an over layer. The over layer also has a role of protecting the photosensitive layer. However, due to the presence of such an over layer, there is a problem of image quality deterioration due to light scattering during laser exposure, and a pre-water washing step for removing the over layer is required prior to alkali development during development. In addition, there is a problem in that a step of applying an overlayer after applying the photosensitive layer is necessary in manufacturing.

On the other hand, in JP-A-2001-290271 (Patent Document 1), JP-A-2002-244288 (Patent Document 2), and JP-A-2002-287340 (Patent Document 3), a vinyl group is substituted on the side chain. A negative photosensitive lithographic printing plate utilizing a photopolymerization reaction of a monomer or polymer having a phenyl group is described. Unlike the acrylate system, these do not need to have an overlayer and have sufficient sensitivity to form a sufficient image. Although these lithographic printing plates contain an organic boron salt as a polymerization initiator in the photosensitive layer, it is extremely useful from the viewpoint of sensitivity and printing durability, but by using the organic boron salt, an image portion of the plate-making product can be obtained. There is a tendency that the halftone dot portion and the fine line portion of (exposure portion) tend to be thick, and the resulting printed matter also has a problem of lowering the image quality. As a conventionally known development processing method for a photosensitive lithographic printing plate, Japanese Patent Publication No. 56-39464 (Patent Document 4) contains benzyl alcohol in the developer, and Japanese Patent Application Laid-Open No. 2001-12147 includes a developer. A method of containing a polyoxyethylene-polyoxypropylene polymer in Japanese Patent Application Laid-Open No. 2001-278085 (Patent Document 5) containing at least one of amino alcohols and alkylethylene glycols in a developer. JP-A 2005-196143 (Patent Document 6) discloses an eluent that dissolves a photosensitive layer in an unexposed area (or promotes elution, such as a method of containing an aromatic anionic surfactant having a polyalkylene group in a developer. A method as an agent) is disclosed. However, these development methods do not provide a sufficient balance between the dissolution of the unexposed area and the printing durability of the exposed area. There is a problem that a normal printed matter cannot be obtained due to insufficient printing durability.
JP 2001-290271 A JP 2002-244288 A JP 2002-287340 A Japanese Patent Publication No.56-39464 JP 2001-278085 A JP 2005-196143 A

  Therefore, an object of the present invention is to develop a photosensitive lithographic printing plate development method having a photosensitive layer containing at least an organic boron salt on a support, which has a good elution property in a non-image area and a stable developability. In addition, when printing, both image quality and printing durability are excellent.

The above object of the present invention has been achieved by the following invention.
1) In the development processing method of a photosensitive lithographic printing plate having a photosensitive layer containing at least an organic boron salt on a support, the photosensitive lithographic printing plate contains at least one compound selected from Chemical Formula 1 below, and the content of silicate compound is SiO. _{2. A} method for developing a photosensitive lithographic printing plate, wherein the processing is performed using a developing solution having a molar amount of 0.01 mol or less per liter.

  According to the present invention, the development processing method of a photosensitive lithographic printing plate having a photosensitive layer containing at least an organic boron salt on a support has good developability and stable developability of non-image areas, and It is excellent in image quality and printing durability at the time of printing.

[Developer]
In the development processing method of a photosensitive lithographic printing plate having a photosensitive layer containing at least an organic boron salt on a support, the present invention is a compound represented by the following general formula (1) as an eluent contained in the developer. (Hereinafter referred to as a glycol compound).

  In the formula, X represents a monocyclic or bicyclic aryl group (for example, phenyl group, naphthyl group) or a heterocyclic group (for example, pyridyl group, imidazolyl group, quinolinyl group, pyrimidyl group, pyrazolyl group, thiazolyl group, benzthiazolyl group). These may have a substituent (for example, methyl group, ethyl group, n-propyl group, chloro group, bromo group, methoxy group, phenoxy group, ethylsulfonamide group, acetamide group, etc.). Particularly preferred for X is a phenyl group, a naphthyl group, or a pyridyl group. L represents a divalent linking group composed of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom, such as an alkylene group (for example, a methylene group, an ethylene group, a propylene group), an ether structure, a thioether structure, Examples include an amide structure and a ureido structure, and two or more of these may be contained. A represents an alkylene group having 2 or more carbon atoms, preferably an alkylene group having 2 to 5 carbon atoms, and particularly preferably an ethylene group or a propylene group. l is 0 or 1. m represents an integer of 1 or more, and a preferable range varies depending on the molecular structure, but a range of approximately 1 to 10 is preferable, and a particularly preferable range is a range of 1 to 5. n represents an integer of 1 or more, preferably 1 or 2. Specific examples of the general formula (1) are shown below.

  The content of the glycol compound contained in the developer is from 0.001 to 10% by mass, particularly preferably from 0.2 to 5% by mass.

  The developer of the present invention is alkaline and the pH is in the range of 10 to 13.5, but is preferably in the range of 10.5 to 12.5. The developing solution of the present invention is an aqueous developing solution in which an alkaline compound such as sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, etc. is dissolved, which selectively dissolves unexposed portions well. Can be exposed, which is extremely preferable. Furthermore, various alcohols such as ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, and glycerin may be added to the alkaline developer.

  The developer of the present invention particularly preferably contains an alkanolamine in addition to the glycol compound as an eluent. The content of the alkanolamine contained in the developer is such that the content of the glycol compound is 1 part by weight. On the other hand, 0.1 to 20 parts by mass is a preferable range, and a particularly preferable range is between 1 to 10 parts by mass. Particularly preferred alkanolamines are compounds represented by the following general formula (2).

In the formula, R ₁₁ represents an alkyl group having 1 to 10 carbon atoms. R ₁₂ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl group may have a hydrophilic substituent such as a hydroxyl group, a carboxylic acid group, or a sulfonic acid group. R ₁₁ and R ₁₂ preferably have 1 to 6 carbon atoms. P ₁₁ and P ₁₂ represent an integer of 2 or more, and may be the same or different. The preferred range of P ₁₁ and _{P 12} is 2-6.

  Examples of the compound of the general formula (2) in the present invention are shown below, but are not limited thereto.

Silica compounds such as sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate, and ammonium silicate, which are generally included in the developer, are circulated in the developer tank of the automatic processor or circulating when a large amount of the plate is made by the automatic processor. There is a problem that crystals tend to precipitate in the pipe and the maintenance becomes complicated. Therefore, it is a preferred embodiment that the developer of the present invention does not substantially contain these silicate compounds. Here, “substantially” refers to a range in which crystals do not precipitate, and the amount of the silicate compound that can be contained varies depending on the composition of the developer, pH, etc., but specifically, the content of the silicate compound in the developer is the amount of SiO ₂ As 0.01 mol or less per liter.

  Various surfactants can be added to the developer used in the present invention as needed for the purpose of promoting developability, dispersing development debris, and improving the ink affinity of the printing plate image area. Preferred surfactants include common anionic, cationic, nonionic and amphoteric surfactants, and particularly preferred surfactants include alkylbenzene sulfonic acid and alkylnaphthalene sulfonic acid. The activator can be used alone or in combination of two or more kinds, and is preferably added to the developer in the range of 0.001 to 10% by mass, more preferably 0.01 to 5% by mass.

  It is advantageous in terms of transportation that the developer used in the present invention is a concentrated solution in which the water content is less than that in use, and is diluted with water at the time of use. The degree of concentration in this case is suitably such that each component does not cause separation or precipitation, and depending on the content, it can usually be concentrated to about concentrate: water = 1: 0 to 1:10. In addition, since the container is alkaline, it is preferable to use a material that does not permeate carbon dioxide and that does not break during transportation for safety. Usually, a resin container such as a hard bottle or a cubicener is preferably used.

  In the processing method of the present invention, the processing is performed with a normal automatic processor after exposure. An automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for conveying a printing plate, each processing liquid tank and a spray tank, and is generally in a developing tank filled with the developing liquid. There is a method in which the printing plate is immersed and conveyed by a guide roll or the like, and a developing process is carried out. In addition, a developing solution assembled by a pump is sprayed from a spray nozzle and developed. 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 The post-treatment of the printing plate of the present invention can be used in various combinations of these treatments. For example, development → washing → a rinsing liquid treatment containing a surfactant, or development → water washing → finishing liquid treatment is a rinse liquid or Less fatigue of the finisher liquid 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. 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. The planographic printing plate obtained by such processing is loaded on an offset printing machine and used for printing.

[Photosensitive planographic printing plate]
The photosensitive lithographic printing plate having a photosensitive layer containing at least the organic boron salt of the present invention on a support will be described.

[Organic boron salt]
The photosensitive layer of the photosensitive lithographic printing plate of the present invention contains at least an organic boron salt as a polymerization initiator. As the organic boron salt, it is particularly preferable to use a compound having an organic boron anion represented by the following general formula (3).

In the general formula (3), R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ may be the same or different, and may be an alkyl group, an aryl group, an aralkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, Represents a heterocyclic group. Of these, it is particularly preferred that one of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ is an alkyl group and the other substituent is an aryl group.

  In the above-mentioned organoboron anion, a cation that forms a salt is simultaneously present. Examples of the cation in this case include alkali metal ions and onium ions. Examples of onium salts include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts. In the case of using a salt of an alkali metal ion or onium compound and an organic boron anion, the addition of a sensitizing dye separately imparts photosensitivity in the wavelength range of light absorbed by the dye.

  One of the preferred embodiments according to the present invention is a photosensitive composition containing an organic boron salt together with a sensitizing dye for sensitizing in the wavelength range of 380 nm to 1300 nm. In this case, the organic boron salt is from visible light to infrared light. In this wavelength region, no photosensitivity is exhibited, and the addition of a sensitizing dye exhibits photosensitivity to light in such a wavelength region. Examples of particularly preferred organic boron salts are shown below.

  There is a preferred range for the proportion of the organic boron salt in the photosensitive layer composition, and the organic boron salt is included in the range of 0.1 to 50 parts by mass in the total 100 parts by mass of the photosensitive layer composition. Preferably it is.

[Sensitizing dye]
The sensitizing dye contained in the photosensitive layer of the photosensitive lithographic printing plate of the present invention sensitizes the decomposition of the photopolymerization initiator in the wavelength range of 380 nm to 1300 nm, and various cationic dyes, anionic dyes and As neutral dyes having no charge, merocyanine, coumarin, xanthene, thioxanthene, azo dyes and the like can be used. Among these, particularly preferable examples are dyes selected from cyanine, carbocyanine, hemicyanine, methine, polymethine, triarylmethane, indoline, azine, thiazine, xanthene, oxazine, acridine, rhodamine, and azamethine dyes as cationic dyes. It is. In combination with these cationic dyes, they are preferably used because of their particularly high sensitivity and excellent storage stability. Furthermore, in recent years, an output machine (plate setter) equipped with a violet semiconductor laser having an oscillation wavelength in the range of 380 to 410 nm has been developed. As a photosensitive system having high sensitivity corresponding to this output machine, a system containing a pyrylium compound or a thiopyrylium compound as a sensitizing dye is preferable. Examples of sensitizing dyes according to the present invention are shown below.

  Among the above sensitizing dyes, a system that gives light sensitivity to light in the near infrared to infrared wavelength region of 750 nm or more is particularly preferable, and it is necessary to have absorption in such a wavelength region as a sensitizing dye. There are particularly preferred examples used for such purposes.

[Polymer having polymerizable double bond in side chain and carboxyl group-containing monomer as copolymerization component]
The polymer having a polymerizable double bond in the side chain preferably contained in the photosensitive layer of the photosensitive lithographic printing plate of the present invention and having a carboxyl group-containing monomer as a copolymerization component is preferably an alkali-soluble polymer. The proportion of the carboxyl group-containing monomer contained in the polymer composition is preferably 5% by mass or more and 99% by mass or less in 100% by mass of the total composition. It may not dissolve. More preferably, the ratio of the carboxyl group-containing monomer contained in the copolymer composition is 10% by mass or more and 80% by mass or less, particularly 20% by mass or more and 70% by mass or less, in 100% by mass of the total composition. preferable. Further, the ratio of the monomer having a polymerizable double bond contained in the copolymer composition is preferably 1% by mass or more and 95% by mass or less, more preferably 10% by mass in 100% by mass of the total composition. The content is 80% by mass or less and particularly preferably 20% by mass or more and 75% by mass or less.

  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.

  When using a polymer in which a polymerizable double bond is introduced into the side chain of an alkali-soluble polymer having a carboxyl group, it is possible to give a highly sensitive negative photosensitive composition in combination with the organic boron salt described above. In addition, since high sensitivity in a wide wavelength range can be realized in combination with the above-described sensitizing dye, scanning exposure using various laser beams can be supported. Monomers for introducing a polymerizable double bond into the polymer side chain include allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl vinyl methacrylate, β-phenyl vinyl. Examples include acrylate, vinyl methacrylamide, vinyl acrylamide, α-chlorovinyl methacrylate, α-chlorovinyl acrylate, β-methoxyvinyl methacrylate, β-methoxyvinyl acrylate, vinylthioacrylate, vinylthiomethacrylate, 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 general formula (4) in the side chain.

In the formula, Z ₃ represents a linking group, and R ₃₁ , R ₃₂ , and R ₃₃ 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 ₃₄ represents a substitutable group or atom. n ₃ represents 0 or 1, m ₃ represents an integer of 0 to 4, and k ₃ represents an integer of 1 to 4.

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 ₃₅ ) —, —C (O) —O—, —C (R ₃₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, and a group represented by the following chemical formula 22 alone or in combination of two or more. Here, R ₃₅ and R ₃₆ 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 General formula (4) is shown below, it is not limited to these examples.

Among the groups represented by the general formula (4), there are preferable ones. That is, it is preferable that R ₃₁ and R ₃₂ are hydrogen atoms and R ₃₃ 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 ₃ , those containing a heterocyclic ring are preferred, and those in which k ₃ is 1 or 2 are preferred.

  Examples of polymers having a group represented by the general formula (4) 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. Examples of other monomers include styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene, 4-methoxystyrene, and other styrene derivatives, methyl methacrylate, Methacrylic acid alkyl esters such as ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and dodecyl methacrylate, aryl methacrylates such as phenyl methacrylate and benzyl methacrylate, or alkylaryl Esters, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate Examples of amino group-containing methacrylic acid esters or acrylic acid esters corresponding to these corresponding methacrylic acid esters, or monomers having phosphoric acid groups such as vinylphosphonic acid, or amino group-containing monomers such as allylamine and diallylamine Or sulfonic acids such as vinyl sulfonic acid and its salt, allyl sulfonic acid and its salt, methallyl sulfonic acid and its salt, styrene sulfonic acid and its salt, 2-acrylamido-2-methylpropane sulfonic acid and its salt Monomers having a nitrogen group, monomers having a nitrogen-containing heterocyclic ring such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole and N-vinylcarbazole, or 4-vinylbenzyltrimethyl as a monomer having a quaternary ammonium base A Monium chloride, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinylbenzylpyridinium chloride, etc. Acrylonitrile, methacrylonitrile, and acrylamide or methacrylamide derivatives such as acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, N-isopropylacrylamide, diacetoneacrylamide, N-methylolacrylamide, N-methoxyethylacrylamide, 4-hydroxyphenylacrylamide And even acrylonite Ryl, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, etc., and vinyl ethers such as methyl vinyl ether, butyl vinyl ether, etc. In addition, various monomers such as N-vinylpyrrolidone, acryloylmorpholine, tetrahydrofurfuryl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, and glycidyl methacrylate can be used.

  There is a preferable range for the molecular weight of the polymer according to the present invention, and the mass 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.

[Ethylenically unsaturated compound]
The photosensitive layer of the photosensitive lithographic printing plate of the present invention preferably further contains an ethylenically unsaturated compound. By combining this, a higher sensitivity can be realized, and a lithographic printing plate having excellent printing performance can be obtained. be able to.

  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 similarly used, 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, which is extremely preferable for producing a highly sensitive negative 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 ₄ represents a linking group, and R ₄₁ , R ₄₂ and R ₄₃ 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 ₄₄ represents a substitutable group or atom. m ₄ represents an integer of 0 to 4, and k ₄ represents an integer of 2 or more.

Further details will be described. As the linking group for Z ₄ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₄₅ ) —, —C (O) —O—, —C (R ₄₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₄₅ and R ₄₆ 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 general formula (5), there are preferable compounds. That is, R ₄₁ and R ₄₂ are hydrogen atoms, R ₄₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and k ₄ is preferably a compound of 2-10. Although the specific example of a compound represented by General formula (5) below is shown, it is 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 composition, and the ethylenically unsaturated compound is 1 to 60 parts by mass in 100 parts by mass of the total photosensitive layer composition. It is preferably included in the range, and more preferably in the range of 5 to 50 parts by mass.

  In the photosensitive layer composition of the present invention, a trihaloalkyl-substituted compound is preferably used in combination with the organic boron salt as a photopolymerization initiator. By using these in combination, further enhancement of sensitivity can be realized. The trihaloalkyl-substituted compound mentioned here is specifically a compound having at least one trihaloalkyl group such as a trichloromethyl group or a tribromomethyl group in the molecule, and preferred examples include the trihaloalkyl group. Examples of the compound bonded to the nitrogen heterocyclic group include s-triazine derivatives and oxadiazole derivatives, or a trihaloalkylsulfonyl compound in which the trihaloalkyl group is bonded to an aromatic ring or a nitrogen-containing heterocyclic ring via a sulfonyl group. Can be mentioned.

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

  When the above-described trihaloalkyl-substituted compound is used in combination, the proportion of the organic boron is such that the trihaloalkyl-substituted compound is contained in the range of 0.1 to 50 parts by mass with respect to 1 part by mass of the organic boron salt. preferable.

  As the photopolymerization initiator contained in the photosensitive layer of the photosensitive lithographic printing plate, any compound can be used as long as it is a compound capable of generating radicals by light irradiation in addition to the organic boron salt and the trihaloalkyl-substituted compound. Examples thereof include hexaarylbisimidazole, titanocene compound, ketoxime compound, thio compound, and organic peroxide.

  There is a preferred range in the quantitative ratio between the sensitizing dye and the photopolymerization initiator. The photopolymerization initiator is preferably used in the range of 0.01 to 100 parts by mass, more preferably in the range of 0.1 to 50 parts by mass of the photopolymerization initiator with respect to 1 part by mass of the sensitizing dye. Is preferably used.

  Since the photosensitive layer of the photosensitive lithographic printing material of the present invention is immediately cured by light irradiation without being affected by oxygen in the air and becomes insoluble in the developer, it is not necessary to provide an over layer on the photosensitive layer. Also, it has the advantage that it can be developed and printed satisfactorily without any heat treatment after exposure.

  A polymerization inhibitor can be preferably added as another element constituting the photosensitive layer. 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 1 part by mass of the ethylenically unsaturated compound.

  Addition of a colorant can be preferably performed as another element constituting the photosensitive layer. The colorant is used for the purpose of enhancing the visibility of the image area after exposure and development processing, and includes various types such as carbon black, phthalocyanine dyes, triarylmethane dyes, anthraquinone dyes, and azo dyes. These pigments and pigments can be used, and can be preferably added in the range of 0.005 to 0.5 parts by mass with respect to 1 mass of binder.

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

  Regarding the thickness of the photosensitive layer itself when used as a lithographic printing plate material, it 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. It is extremely preferable for greatly improving the performance. For the photosensitive layer, a solution in which the above-described elements are mixed is prepared, and is coated and dried on a support using various known coating methods. As the support, for example, a film or polyethylene-coated paper may be used, but a more preferable support is an aluminum plate that is polished and has an anodized film.

  A particularly preferable laser light source used for the laser scanning exposure according to the present invention is a laser having an oscillation wavelength in the near infrared region, and various semiconductor lasers, solid lasers such as YAG lasers and glass lasers are most preferable.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples as well as the effects. The part in an Example shows a mass part.

<Preparation of photosensitive lithographic printing material>
The following photosensitive layer coating solution is applied on a 0.24 mm thick aluminum plate that has been grained and anodized to a dry thickness of 3.5 μm, and dried with warm air at 75 ° C. A photosensitive lithographic printing material for testing was obtained.

<Photosensitive layer coating solution prescription>
Polymerizable double bond-containing polymer (P-1; mass average molecular weight of about 90,000) 10 parts by mass Organic boron salt (BC-2) 2 parts by mass Ethylenically unsaturated compound (C-5) 2 parts by mass Sensitizing dye ( S-39) 0.4 part by weight Trihaloalkyl-substituted compound (T-1) 1 part by weight 10% phthalocyanine dispersion 0.5 part by weight 2,6-di-tert-butylcresol 0.1 part by weight 1,4- Dioxane 70 parts by mass Cyclohexanone 20 parts by mass

<Laser exposure>
The photosensitive lithographic printing material for testing was prepared by using PT-R4000 manufactured by Dainippon Screen Mfg. Co., Ltd., an external drum plate setter equipped with an 830 nm semiconductor laser, drum rotation speed of 500 rpm, and laser irradiation energy of 80 mJ / cm ^2. (2400 dpi, 175 lines, no calibration).

<Development processing>
After exposure, an automatic developing machine PD-1310 for PS plate manufactured by Dainippon Screen Mfg. Co., Ltd. was used as an automatic developing machine, and development processing (developing liquid temperature 30 ° C.) was performed using the following developing solutions (Table 1) of the present invention. , Development time 15 seconds), followed by washing with water, and then applying a gum solution having the following formulation to obtain comparative and lithographic printing plates of the present invention.

<Comparison and Invention Developer>
35% sodium alkylnaphthalene sulfonate
(Surfactant manufactured by Kao Corporation) 30g
Tetramethylammonium hydroxide 60g
Phosphoric acid 10g
EDTA2 sodium 1g
Eluent (Table 1) 20g
1L with water

<Gum solution>
Monopotassium phosphate 5g
Gum arabic 25g
Dehydroacetic acid 0.5g
EDTA2 sodium 1g
1L with water

<Printing test>
The planographic printing plate obtained by the above development processing is mounted on a printing machine Ryobi 560, and printing is performed using a 10% isopropyl alcohol aqueous solution as a moisturizing liquid and F gloss ink (hard type) manufactured by Dainippon Ink and Chemicals as an ink. The prints of the 5000th sheet and the 100,000th sheet were sampled on white coated paper. The conditions during printing were an indoor temperature of 23 ° C. and an indoor humidity of 65%.

<Print quality evaluation criteria>
With the printed material sampled on 5000 sheets, the halftone dot area ratio of the portion corresponding to 50% halftone dots was measured (measuring device X-RiteDot) and evaluated according to the following criteria. The results are shown in Table 1. Note that the image quality is better as the halftone dot area ratio is closer to 50%.
4: The dot area ratio is 50% or more and less than 55% 3: The dot area ratio is 55% or more and less than 60% 2: The dot area ratio is 60% or more and less than 65% 1: The dot area ratio is 65% or more

<Evaluation criteria for printing durability>
The printed matter sampled with 100,000 sheets was visually or microscopically (50 times magnification) observed for defects in the image area, and the printing durability was evaluated according to the following criteria. The larger the evaluation standard value, the better the printing durability.
4: No defects in the image area are confirmed on the entire printed surface 3: Defects in the image area of the printed material cannot be visually confirmed, but can be confirmed with a microscope 2: Images in the image area of the printed material can be visually confirmed 1: Image area of the printed material Most of are missing

<Evaluation results>

  From the results in Table 1, the developer containing the glycol compound of the present invention is superior to the developer containing the comparative eluent in both image quality and printing durability. It can be seen that the developer of the present invention is a method for developing a photosensitive lithographic printing plate having good elution of non-image areas and little influence on printing durability.

  Using the same photosensitive lithographic printing plate as in Example 1, the same exposure, development and printing as in Example 1 were performed, and the same evaluation was performed. The following formulation was used only for the developer.

<Comparison and Invention Developer>
35% sodium alkylnaphthalene sulfonate
(Surfactant manufactured by Kao Corporation) 30g
Tetramethylammonium hydroxide 60g
Phosphoric acid 10g
EDTA2 sodium 1g
PG-1 (glycol compound) (Amounts listed in Table 2)
AA-3 (alkanolamines) (amounts listed in Table 2)
1L with water

<Evaluation results>

  From the results of Table 2, the developer of the present invention alone has superior image quality and printing durability over the developer containing the amino alcohols alone, which is a comparison. The glycol compound of the present invention and the amino alcohol Developers containing both types are more superior in both image quality and printing durability. Therefore, it can be seen that the developer of the present invention is a method for processing a photosensitive lithographic printing plate that has very good elution in the non-image area and very little influence on printing durability.

Claims (1)

In a development processing method of a photosensitive lithographic printing plate having a photosensitive layer containing at least an organic boron salt on a support, the photosensitive lithographic printing plate contains at least one compound selected from Chemical Formula 1 below, and the content of silicate compound is SiO ₂ content. A development process for a photosensitive lithographic printing plate, characterized in that the development is carried out using a developing solution of 0.01 mol or less per liter.