JP2006215119A - Negative photosensitive lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative photosensitive lithographic printing plate having high sensitivity without disposing an over layer, excellent in scratch resistance, blocking resistance and the dissolving property of a non-image area, free from pinholes, and excellent also in cleaner resistance. <P>SOLUTION: The negative photosensitive lithographic printing plate has a photopolymerizable photosensitive layer on a support but does not have an over layer, wherein the photosensitive layer contains polymer particles having an average particle diameter equal to 80-300% of the thickness of the photosensitive layer and a fluorochemical surfactant. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a negative photosensitive lithographic printing plate. Specifically, the present invention relates to a negative photosensitive lithographic printing plate having high sensitivity and excellent scratch resistance and blocking resistance without an overlayer for blocking oxygen.

A negative photosensitive lithographic printing plate that has been widely used conventionally has a photosensitive coating (photosensitive layer) coated on an aluminum support. In this coating film, the exposed portion is cured, and the 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 having a wavelength of 700 to 1300 nm can be easily used, and a photosensitive lithographic printing plate corresponding to the laser light has attracted attention.

  Examples of photosensitive lithographic printing plates that utilize photopolymerization and that are compatible with near-infrared lasers include, for example, 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.

  In order to solve the above problems, photosensitive lithographic printing plates that do not require an overlayer have been proposed. For example, JP 2001-290271 A (Patent Document 1), JP 2003-122002 A (Patent Document 2). JP 2003-315990 A (Patent Document 3) and the like. However, when the over layer is not provided, there is a problem that the scratch resistance or blocking resistance of the photosensitive layer is deteriorated.

  On the other hand, use of rubber-elastic particles or polymer particles is disclosed in JP-A-11-109642 (Patent Document 4) and JP-A-2001-183818 (Patent Document 5). However, the inclusion of polymer particles or the like in the photosensitive layer tends to cause pinholes on the coating film of the photosensitive layer, the problem that the elution of non-image areas (unexposed areas) decreases, A new problem (hereinafter referred to as “cleaner resistance”) occurs when the strength of the image area decreases and the printing durability deteriorates when a cleaner is applied.

On the other hand, it is known to use a fluorinated surfactant in the photosensitive layer. For example, it is described in JP-A-9-134011 (Patent Document 6) and JP-A-9-197654 (Patent Document 7). Japanese Patent Laid-Open No. 11-352683 (Patent Document 8)
JP 2001-290271 A JP 2003-122002 A JP 2003-315990 A Japanese Patent Laid-Open No. 11-109642 JP 2001-183818 A JP-A-9-134011 JP-A-9-197654 JP-A-11-352683

  Accordingly, an object of the present invention is to provide a negative photosensitive lithographic printing plate which has high sensitivity without providing an over layer, is excellent in scratch resistance, blocking resistance, and non-image area elution, and has no pinholes. There is. Furthermore, an object of the present invention is to provide a negative photosensitive lithographic printing plate excellent in cleaner resistance.

The above object of the present invention has been basically achieved by the following invention.
1) In a negative photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on a support and not having an overlayer, the photosensitive layer is 80 to 300% of the thickness of the photosensitive layer. A negative photosensitive lithographic printing plate comprising polymer particles having an average particle size and a fluorosurfactant.
2) The negative photosensitive lithographic printing plate as described in 1) above, wherein the polymer particles are silicone resin particles.

  According to the present invention, the disadvantages due to the provision of the over layer are solved, and the problems due to the absence of the over layer, that is, the deterioration of scratch resistance and blocking resistance are improved, and further the elution of non-image areas is improved. Pinholes and cleaner resistance are improved at the same time.

  The photosensitive layer of the present invention provides a photopolymerizable negative photosensitive lithographic printing plate and contains at least a photopolymerization initiator and a polymerizable compound. The polymerizable compound contains at least one of a polymerizable monomer, oligomer, or polymer. The photosensitive layer of the present invention contains polymer particles and a fluorosurfactant in addition to the above configuration.

  Since the lithographic printing plate of the present invention does not have an over layer, it has been found that the relationship between the thickness of the photosensitive layer and the average particle diameter of the polymer particles is very important in order to obtain the above-mentioned objects and effects of the present invention. It was. That is, if the polymer particle diameter is too small relative to the thickness of the photosensitive layer, the effect on scratch resistance and blocking resistance cannot be obtained. Conversely, even if the polymer particle diameter is too large relative to the thickness of the photosensitive layer, scratch resistance The effect on the properties cannot be obtained, pinholes are easily generated on the coated surface of the photosensitive layer, and the image quality and cleaner resistance during printing are also reduced. Therefore, the average particle diameter of the polymer particles contained in the photosensitive layer of the present invention is 80 to 300% with respect to the thickness of the photosensitive layer. A preferable average particle diameter range of the polymer particles is 90 to 250% with respect to the thickness of the photosensitive layer, and a more preferable range is 100 to 200%. The thickness of the photosensitive layer itself is preferably formed on the support with a dry thickness in the range of 0.5 μm to 10 μm, and particularly preferably in the range of 1 μm to 5 μm in order to ensure high printing durability. The thickness of the photosensitive layer can be measured by observing the cross section with a scanning electron microscope.

  The polymer particles used in the present invention are preferably organic polymer particles, such as silicone resin particles, poly (meth) acrylate, acrylate resin particles such as polymethyl (meth) acrylate, polystyrene resin particles, polystyrene and poly (meth) acrylate. Copolymer resin particles, polyolefin resin particles such as polyethylene and polypropylene, halogenated polyolefin resin particles such as polyfluoroethylene and polychloroethylene, polyamide resin such as nylon, polyester resin particles such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate resin Particles and the like. Particularly preferable polymer particles are silicone resin particles, which are commercially available as Tospearl series from Toshiba Silicone Co., Ltd. and can be obtained.

  The shape of the polymer particles used in the present invention is preferably a spherical shape that is more nearly spherical.

  The content of the polymer particles is preferably from 0.1 to 10% by weight, more preferably from 0.2 to 5% by weight, particularly from 0.3 to 3% by weight, based on the total solid content of the photosensitive layer. Is preferred.

  If only polymer particles are added properly to the photosensitive layer, the frequency of occurrence of pinholes on the coated surface of the photosensitive layer cannot be suppressed, and there is a problem that the elution property of the non-image area is deteriorated. Accordingly, the present invention has found that the elution properties of pinholes and non-image areas can be remarkably improved by further adding a fluorosurfactant to the photosensitive layer.

  Examples of the fluorosurfactant that can be used in the present invention include perfluoroalkyl group-containing carboxylates, perfluoroalkyl group-containing sulfonates, perfluoroalkyl group-containing sulfate esters, and perfluoroalkyl group-containing phosphates. Anionic fluorine-based surfactants such as, perfluoroalkyl group-containing amine salts, perfluoroalkyl group-containing quaternary ammonium salts and other cationic fluorine-based surfactants, perfluoroalkyl group-containing carboxyl betaines, and perfluoroalkyl group-containing Amphoteric fluorosurfactants such as aminocarboxylates, perfluoroalkyl polyoxyethylene ethers, perfluoroalkenyl polyoxyethylene ethers, other perfluoroalkyl group-containing oligomers, perfluoroalkyl group-containing polymers, perfluoro Alkyl group-containing polymer ester, perfluoroalkyl group-containing sulfonamide polyethylene glycol adduct, and the like. Specific examples include surfactants described in JP-A-9-134011 and activators shown in the following chemical formulas 1 and 2.

  Nonionic ones of perfluoroalkenyl polyoxyethylene ether, perfluoroalkyl group-containing oligomer, perfluoroalkyl group-containing polymer, and perfluoroalkyl group-containing polymer ester are preferable. More preferably, it is a nonionic fluorosurfactant containing 4 to 20 ethyleneoxy groups in the molecule, and more preferably 4 to 20 ethyleneoxy groups and a perfluoroalkenyl group in the molecule. It is a nonionic fluorosurfactant (perfluoroalkenyl polyoxyethylene ether).

  Specific examples of perfluoroalkenyl polyoxyethylene ether are shown below. Among these, Rf is a perfluoroalkenyl group, and those bonded to one end or both ends of the ethyleneoxy group, or those having a (poly) glycerin skeleton are exemplified. More preferably, it has a (poly) glycerin skeleton, and the number n of ethyleneoxy groups in the molecule is 4 to 20.

  In the formula, R represents an aliphatic group, and Rf represents a perfluoroalkenyl group. Preferred examples of Rf are shown below.

  The above perfluoroalkenyl polyoxyethylene ether is from Neos Co., Ltd. (F-1) One-end type is FTX-212M (12 ethyleneoxy), (F-2) Both-end type is FTX-209F (ethylene 9 oxy), 213F (13 ethyleneoxy), (F-3) glycerin type is FTX-208G (8 ethyleneoxy), 218G (18 ethyleneoxy), (F-4) diglycerin type is FTX- Available as 204D (4 ethyleneoxy), FTX-208D (8 ethyleneoxy), FTX-212D (12 ethyleneoxy), FTX-218D (18 ethyleneoxy)

  About content of a fluorochemical surfactant, 0.001-0.5 mass% is preferable with respect to the total solid of a photosensitive layer, and the range of 0.005-0.3 mass% is more preferable.

  The photosensitive lithographic printing plate of the present invention has a photosensitive layer that is highly sensitive without having an over layer. The means for obtaining such a photosensitive layer is not particularly limited. For example, a polymer described in JP-A-2001-290271 or a polymerizable monomer is used, or a urethane compound described in JP-A-2003-122002 is used. In addition, use of a non-fluorinated nonionic surfactant having an HLB value of 10 or less described in JP-A No. 2003-315990 can be mentioned. Among these, from the viewpoint that high sensitivity and high printing durability can be stably obtained, the resin has a phenyl group (vinylphenyl group) substituted with a vinyl group in the side chain described in JP-A-2001-290271. It is preferable to use a polymer as a binder resin.

  Below, the polymer which has a vinylphenyl group in a side chain is demonstrated. The polymer having a vinylphenyl group in the side chain is one in which the phenyl group is bonded to the main chain directly or via a linking group, and the linking group is not particularly limited, and any group, atom or their group can be used. A complex group may be mentioned. The phenyl group may be substituted with a substitutable group or atom other than a vinyl group, and the vinyl group is a halogen atom, carboxy group, sulfo group, nitro group, cyano group, amide group, amino group. , An alkyl group, an aryl group, an alkoxy group, an aryloxy group and the like may be substituted. More specifically, the polymer having a vinylphenyl group in the side chain described above has a group represented by the following general formula in the side chain.

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

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

  Examples of the heterocyclic group include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, isoxazole ring, oxazole ring, oxadiazole ring, isothiazole ring, thiazole ring, thiadiazole ring, thiatriazole ring, indole ring. , Indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring, benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, quinoxaline ring, etc. A nitrogen-containing heterocyclic ring, a furan ring, a thiophene ring, and the like, and a substituent may be bonded to these heterocyclic rings. 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 ₁ and R ₂ are hydrogen atoms and R ₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.). Further, the linking group Z ₁ preferably includes a heterocyclic ring, and k ₁ is preferably 1 or 2.

  As the polymer having a vinylphenyl group in the side chain as shown in the above example, it is preferable that the polymer has solubility in an alkaline aqueous solution, and therefore, it is particularly a polymer containing a carboxyl group-containing monomer as a copolymerization component. preferable. In this case, the proportion of the monomer having a vinylphenyl group in the side chain in the copolymer composition is preferably 5% by mass to 95% by mass with respect to 100% by mass of the total copolymer composition. The range of -95 mass% is more preferable, and the range of 20-90 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.

  Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, acrylic acid 2-carboxyethyl ester, methacrylic acid-2-carboxyethyl ester, crotonic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, and fumaric acid mono Examples include alkyl esters, 4-carboxystyrene and the like.

  In addition to the monomer having a carboxyl group, other monomer components may be introduced into the copolymer to be synthesized and used as a multi-component copolymer. In such cases, monomers that can be incorporated into the copolymer include styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene, and 4-methoxystyrene. Styrene derivatives such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, methacrylic acid-2-ethylhexyl, cyclohexyl methacrylate, methacrylic acid alkyl esters such as dodecyl methacrylate, phenyl methacrylate, benzyl methacrylate Methacrylic acid aryl esters or alkyl aryl esters such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol methacrylate Contains amino groups such as monoester, methacrylic acid methoxypolyethylene glycol monoester, methacrylic acid polypropylene glycol monoester and other alkyleneoxy group-containing methacrylates, methacrylic acid-2-dimethylaminoethyl, methacrylic acid-2-diethylaminoethyl Examples similar to these corresponding methacrylic acid esters as methacrylic acid esters or acrylic acid esters, vinylphosphonic acid or the like as a monomer having a phosphoric acid group, or amino group-containing monomers such as allylamine or diallylamine, or 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 sulfo Monomers having a sulfonic acid group such as acids and salts thereof, monomers having a nitrogen-containing heterocyclic ring such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, or quaternary ammonium bases. As monomers having 4-vinylbenzyltrimethylammonium 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, Acrylamide or methacrylamide derivatives such as diethyl acrylamide, N-isopropyl acrylamide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide , Vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, etc., vinyl ethers such as methyl vinyl ether, butyl vinyl ether, others, N-vinylpyrrolidone, acryloylmorpholine, tetrahydro Furfuryl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyl trimeth Shishiran, it may be used glycidyl methacrylate and 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 shown in Chemical Formula 3 in the copolymer composition described above is maintained. It can be introduced at a rate.

  There is a preferred range for the molecular weight of the polymer as described above, and the mass average molecular weight is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 10,000 to 300,000.

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

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

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

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

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

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

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

  The photosensitive layer of the present invention contains a sensitizing dye. This sensitizing dye is used so as to be compatible with the type of light source of the output machine (for example, argon laser, helium-neon laser, red LED, etc.). It is preferable to contain a sensitizing dye corresponding to scanning exposure using a laser beam having a wavelength range of ˜1000 nm. Specific examples of these sensitizing dyes are shown below.

  The content of the sensitizing dye exemplified above is suitably in the range of 1 to 60% by mass, preferably in the range of 2 to 50% by mass with respect to the photopolymerization initiator described above.

  The photosensitive layer of the present invention contains a polymerizable monomer or oligomer. The molecular weight of the monomer or oligomer is 10,000 or less, preferably 5000 or less. Examples of the compound include compounds having two or more polymerizable double bonds such as acryloyl group, methacryloyl group, and vinylphenyl group.

  Examples of the compound having an acryloyl group or a methacryloyl group as a polymerizable 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, ethylene glycol glycerol tri (meth) acrylate, glycerol epoxy tri (meth) acrylate, trimethylolpropane tri (meth) Acrylate, trimethylolethane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipe Data pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pyrogallol triacrylate.

  A compound having a vinylphenyl group as a polymerizable double bond is typically represented by the following general formula.

In the formula, Z ₂ represents a linking group, and R ₂₁ , R ₂₂ and R ₂₃ 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 ₂₄ 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 ₂ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₅ ) —, —C (O) —O—, —C (R ₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₅ and R ₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

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

Among the compounds represented by the above general formula, there are preferable compounds. That is, R ₂₁ and R ₂₂ are hydrogen atoms, R ₂₃ 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 of 2-10. Although a specific example is shown below, it is not limited to these examples.

  The content of the monomer or oligomer 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 binder resin.

  The photosensitive layer of the present invention preferably contains, as a polymerizable monomer or oligomer, a compound having a urethane bond and a polymerizable double bond (hereinafter referred to as a urethane compound) in addition to the monomer or oligomer described above. By containing the urethane compound, the elution of the non-image area is further improved, and the background stain is improved.

  The urethane compound used in the present invention has at least one urethane bond represented by the following structural formula in the molecule. Examples of the polymerizable double bond include an acryloyl group and a methacryloyl group, and it is preferable to have two or more of these polymerizable double bonds. Furthermore, a urethane compound having 2 to 6 urethane bonds and 4 to 10 polymerizable double bonds is preferable.

  Specific examples of the urethane compound described above are shown below.

  In this invention, it is preferable to contain the content of the said urethane compound in 5-60 mass% with respect to binder resin, and the range of 10-50 mass% is especially preferable.

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

  Since the photosensitive layer of the present invention is not affected by oxygen at the time of exposure, it is not necessary to provide an overlayer for blocking oxygen, and the sensitivity is high and the exposed portion can be sufficiently cured. Absent. Therefore, the photosensitive lithographic printing plate of the present invention can greatly improve the efficiency of the plate making process compared to the conventional one.

  The photosensitive layer of the present invention is coated on a support and dried using various known coating methods. Examples of the coating method include roll coating, dip coating, air knife coating, gravure coating, hopper coating, blade coating, and wire doctor coating.

  For the support of the photosensitive lithographic printing plate of the present invention, for example, a polyester 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. The aluminum support preferably used will be described. The thickness of the aluminum plate used in the present invention is about 0.1 to 0.6 mm. This thickness can be appropriately changed according to the size of the printing press, the size of the printing plate, and the user's desire. Below, the processing method of an aluminum support body is demonstrated.

  The aluminum plate is usually grained to a more preferable 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 preferred 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.

  By electrochemical surface roughening after mechanical surface roughening, crater-like or honeycomb-like pits having an average diameter of about 0.3 to 1.5 μm and an average depth of 0.05 to 0.4 μm are formed on an aluminum plate. It can be made to produce on the surface of 80-100% of area ratio. 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 plate is preferably subjected to chemical etching. 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 amount of dissolved 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 plate treated as described above is further subjected to anodizing treatment. The anodizing treatment can be performed by a method conventionally used in this field. Specifically, when direct current or alternating current is applied to an aluminum plate 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 plate.

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, and electrolysis time 10 to 200 seconds are appropriate. 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 photosensitive lithographic printing plate obtained by coating the photosensitive layer on the aluminum support produced as described above is subjected to laser scanning exposure according to the photosensitive area imparted to the photosensitive layer and exposed. Since the solubility in an alkaline developer is reduced due to crosslinking of the exposed portion, the pattern of the exposed image is formed by eluting the unexposed portion with an alkaline developer described later.

  The alkaline developer used in the present invention preferably has a pH of 10 to 12 at 25 ° C. As an alkaline compound for adjusting the pH of the developer to the above range, sodium hydroxide, potassium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-ethylethanolamine, triethylammonium hydroxide Among them, alkanolamines are particularly preferable. Furthermore, it is also preferable to add various alcohols such as ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin and benzyl alcohol to the alkaline developer. Also, various surfactants can be preferably added. After developing using such an alkaline developer, normal gumming is preferably performed using gum arabic, dextrins and the like.

  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 plate>
The following photosensitive layer coating solution was applied to a 0.24 mm thick aluminum plate that had been grained and anodized so that the dry thickness was 2.5 μm or 3.5 μm, and warm air at 75 ° C. And dried. Table 1 shows the sample contents.
<Photosensitive layer coating solution prescription>
Polymer (P-1; weight average molecular weight of about 90,000) 10 parts by weight Urethane compound (U-1) 3 parts by weight Polymerizable double bond monomer (C-5) 2 parts by weight Photopolymerization initiator 1 (BC-6) ) 2 parts by weight Photopolymerization initiator 2 (BS-1) 1 part by weight Sensitizing dye (S-39) 0.4 part by weight 10% phthalocyanine dispersion 0.5 part by weight Dioxane 70 parts by weight Cyclohexanone 20 parts by weight Polymer particles (Described in Table 1) 0.2 parts by mass or none Surfactant (described in Table 1) 0.01 parts by mass or none

<Polymer particles>
As the polymer particles, silicone resin particles having a true spherical shape (average particle sizes of 0.3, 0.7, 2.0, 3.0, 4.5, 6.0, 7.5, 12.0 μm, 8 Wet type silica fine particles (irregular shape, 4.5 μm) were used as the inorganic fine particles.

<Surfactant>
FTX-218G manufactured by Neos Co., Ltd. (illustrated above) is used as the fluorosurfactant, and polyoxyethylene lauryl ether nonionic surfactant (trade name Emulgen 104P from Kao Corporation) is used as a comparative surfactant. Was used.

  The lithographic printing plate samples obtained as described above were evaluated as follows. The results are shown in Table 2.

<Pinhole evaluation method>
Samples were cut into 1 m ² squares, and a total of 10 coated surfaces (10 m ² minutes in total) were observed for each sample to examine the presence or absence of pinholes.
○: No pinhole.
X: There is a pinhole (one or more pinholes are present).

<Method for evaluating blocking resistance>
The sample is cut into 5 cm ² squares, the burrs on the end face are removed, and the photosensitive layer surface is stacked so that the back surface of the support is in contact, and a weight of 15 kg / cm ² is applied to the photosensitive layer surface, while the temperature is 35 degrees and the humidity is 80% RH. It left still to a warmer for 1 month, and the presence or absence of blocking was confirmed visually.
○: No blocking.
X: There is blocking (one part of the photosensitive layer sticks to the back surface, or two sheets are lifted simultaneously).

<Scratch resistance evaluation method>
A scratch when scratching using a HEIDON-18 type continuous load type scratch tester, wearing a needle with a needle tip of 500 μm, setting the contact angle between the needle tip and the photosensitive layer of the sample to 60 °, and applying a load of 50 g The method of entering was evaluated according to the following evaluation criteria.
○: No scratches.
X: Scratches occur.

<Image quality evaluation method>
Using a sample plate setter equipped with an 830 nm semiconductor laser, PT-R4000 manufactured by Dainippon Screen Mfg. Co., Ltd., the sample was 50% flat under the conditions of drum rotation speed 1000 rpm resolution 2400 dpi and laser irradiation energy 100 mJ / cm ^2. A net exposure was performed. After the exposure, the Dainippon Screen Mfg. Co., Ltd. PS plate automatic developing machine PD-1310 is used as an automatic developing machine, and development processing (developing solution temperature 29 ° C. for 15 seconds) is performed using the following developing solution. A gum solution having the following formulation was applied.

<Developer>
35% sodium alkylnaphthalene sulfonate
(Surfactant manufactured by Kao Corporation) 30g
Tetramethylammonium hydroxide 60g
Phosphoric acid 10g
N-ethyl monoethanolamine 35g
EDTA2Na 1g
1L with water
<Gum solution>
1g potassium phosphate 5g
Gum arabic 25g
Dehydroacetic acid 0.5g
EDTA2Na 1g
1L with water

About the planographic printing plate produced as mentioned above, the sharpness of the edge part of a halftone dot was observed and the image quality was evaluated according to the following evaluation criteria.
○: A uniform halftone image is formed with sharp edges.
X: Unevenness is seen in the edge portion of the image and a non-uniform network image is formed.

<Elution method>
The same exposure as in the image quality evaluation method described above is performed, and a lithographic printing plate (plate size) is processed at a developer temperature of 29 ° C. for 10 seconds using the same automatic developer, developer and gum solution as in the image quality evaluation method described above. Obtained 398 mm × 1100 mm). The elution (developability) of the non-image area of this lithographic printing plate was evaluated according to the following evaluation criteria. The results are shown in Table 2.

○: There is no residual film in the non-image area.
X: There is a residual film in the non-image area.

<Cleaner resistance evaluation method>
In the same manner as the image quality evaluation method described above, exposure and development were performed, and the obtained lithographic printing plate was subjected to a printing test by the following method.

The printing machine is Heidelberg TOK (trademark of Heidelberg's offset printing machine), the ink is New Champion Black H (Dainippon Ink Chemical Co., Ltd.), and the dampening solution is Astro Mark III (Niken Chemical Co., Ltd.) 50% halftone dot of the printed material when 10000 sheets are printed again by repeating the process of wiping the plate with PS Multi Cleaner (Fuji Photo Film Co., Ltd.) after printing 10,000 sheets using a 1% aqueous solution of Images were evaluated according to the following evaluation criteria.
○: There is no omission in the image.
Δ: A part of the image is missing.
X: There is a lack throughout the image.

  The sample of the present invention is superior to the comparative sample in all items of pinhole, blocking resistance, scratch resistance, dissolution property, image quality, and cleaner resistance.

  From the above results, it can be seen that the present invention sufficiently retains the pinhole, blocking resistance, scratch resistance, dissolution property, image quality, and cleaner resistance without deteriorating the image quality and without requiring an over layer.

Claims (2)

  In a negative photosensitive lithographic printing plate having a photopolymerizable photosensitive layer on the support and no overlayer, the photosensitive layer has an average of 80% to 300% with respect to the thickness of the photosensitive layer. A negative photosensitive lithographic printing plate comprising polymer particles having a particle size and a fluorosurfactant.   The negative photosensitive lithographic printing plate according to claim 1, wherein the polymer particles are silicone resin particles.