JP2007111895A - Printing method of lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method which remarkably improves the plate wear resistance of a lithographic printing plate having a photopolymerizable photosensitive layer. <P>SOLUTION: In the printing method of the lithographic printing plate having the photopolymerizable photosensitive layer, a blanket used for printing is made to have a compression value of 0.15 mm or above at the time of compression of 100 N/cm<SP>2</SP>. The lithographic printing plate has the photosensitive layer containing an ethylenic unsaturated compound, a photopolymerization initiator and sensitized pigment in a wavelength region of 380-1,300 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing method of a lithographic printing plate having a photopolymerizable photosensitive layer, and more particularly to a printing method of a lithographic printing plate exposed by a scanning exposure method using near infrared laser light.

  Conventionally, a photosensitive lithographic printing plate widely used as an original plate for a lithographic printing plate uses an aluminum plate as a support and is provided with a photodegradable or photocurable photosensitive layer thereon. These photosensitive layers are solubilized in the developer by actinic rays and the latter are insoluble. Therefore, when this is developed, only the developer soluble portion of the photosensitive layer is removed, and the support surface is exposed. Since the surface of the aluminum support is hydrophilic, the portion where the surface of the support is exposed by development (non-image portion) retains water and repels the oil-based ink. On the other hand, the region (image part) where the photosensitive layer has not been removed by development is oleophilic and repels water and accepts ink.

  Among the lithographic printing plate precursors described above, the so-called negative type image forming material in which the photosensitive layer is insolubilized by actinic rays has a reduced image area due to wear or the like during printing when the exposed area does not sufficiently cure. Because it becomes easier to print, only a small number of copies can be printed. Accordingly, it is important to sufficiently cure the exposed area when printing many sheets.

  In recent years, computer-to-plate (Computer to Plate: hereinafter abbreviated as CTP) technology has been developed and output based on digital data produced on a computer and output directly on a printing plate without outputting it on film. Various types of plate setters equipped with various lasers and photosensitive lithographic printing plates suitable for them have been actively developed.

  Above all, in the output machine using a semiconductor laser or YAG laser emitted in the near infrared region of 750 nm or more, since the output of the light source is equipped with a high output laser of several hundred mW to several watts class, Image formation with high energy is possible. Examples of photosensitive lithographic printing plates compatible with CTP include, for example, JP-A-7-20629, JP-A-7-271029, JP-A-9-185160, JP-A-9-197671, JP-A-9-222731. A latent acid generator utilizing heat generated by photothermal conversion in a combination of a latent acid generator and a near-infrared absorbing dye, as described in Kaihei 9-239945, JP-A-10-142780, etc. A negative-type image forming method is disclosed using decomposition and acid-catalyzed thermal crosslinking using an acid generated in the laser irradiation part.

  Further, examples of systems in which photon mode recording, which is a conventional application of high-sensitivity photopolymer technology, is applied to near-infrared light include, for example, JP-A Nos. 2000-122274, 2000-131833, 2000-181559, In JP-A-2000-194124, etc., in a photopolymer system containing a photopolymerization initiator and an ethylenically unsaturated compound, high sensitivity can be obtained by using various dyes that spectrally sensitize the photopolymerization initiator in near infrared light. A negative recording material is provided.

  However, in a lithographic printing plate as described above, particularly in a photopolymer-based lithographic printing plate containing a photopolymerization initiator and an ethylenically unsaturated compound, it is difficult for light to reach the photosensitive layer / aluminum support interface, If there is a tendency to stop the reaction by curing only the surface of the photosensitive layer, sufficient image strength cannot be obtained, and if it is necessary to print a large number of sheets, a process such as heat treatment or post-exposure is performed after development. It was necessary to increase the film strength.

  On the other hand, ink transfer in the offset printing apparatus is performed twice from the plate to the blanket and from the blanket to the printing medium, and the amount of ink transfer from the blanket to the printing medium determines the printing quality. Then, the ink supplied to the image portion of the printing plate is transferred from the plate to the blanket, and the mechanical contact between the printing plate and the blanket is repeated, so that the image portion of the printing plate is damaged. If sufficient image intensity is not obtained, the area of the image line portion decreases, and particularly disappears in the highlight portion of the printed matter.

As a blanket used for offset printing, for example, in Japanese Patent Application Laid-Open No. 2002-059672 (Patent Document 1), an oil-resistant rubber having an elastic modulus E ′ of 5 to 10 MPa when a dynamic change stress of a surface printing layer is applied. A printing blanket made of the composition is disclosed in JP-A-11-1075 (Patent Document 2), wherein the shear storage elastic modulus G ′ when a dynamic stress is applied is 3 × 10 ⁷ to 8 × 10 ⁷ dyn /. A blanket for offset printing of cm ² is described, and Japanese Patent Laid-Open No. 03-022324 (Patent Document 3) defines the hardness of silicone rubber used for the blanket. However, a blanket used for printing the lithographic printing plate, which tends to have insufficient film strength in the image area, has not been studied so far.
JP 2002-059672 A Japanese Patent Laid-Open No. 11-1075 Japanese Patent Laid-Open No. 03-022324

  Accordingly, an object of the present invention is to provide a printing method that remarkably improves the printing durability of a lithographic printing plate having a photopolymerizable photosensitive layer.

The above object of the present invention has been achieved by the following means.
1. In the printing method of a lithographic printing plate having a photopolymerizable photosensitive layer, the blanket used for printing of the lithographic printing plate has a compression value of 0.15 mm or more when compressed at 100 N / cm ^2. Printing method.
2. 2. The lithographic printing plate according to 1, wherein the lithographic printing plate is a lithographic printing plate having a photosensitive layer containing a sensitizing dye in a wavelength range of 380 nm to 1300 nm, an ethylenically unsaturated compound, a photopolymerization initiator, Printing method.
3. The printing method according to 1 or 2, wherein the scratch strength of the photosensitive layer of the planographic printing plate is 150 g or less.

  According to the present invention, it is possible to provide a printing method of a lithographic printing plate with significantly improved printing durability by carrying out the above means.

The compression value of the blanket used in the printing method of the planographic printing plate of the present invention will be described. As a method for measuring the compression value, the compression value indicates how many millimeters the blanket surface was compressed at the time of compression of 100 N / cm ^{2 according} to the test standard of ISO 0604: 2002 (JIS K7181) using a universal tensile compression tester. . The compression value of a general blanket is about 0.12 mm, but the compression value of the blanket used in the printing method of the lithographic printing plate of the present invention is preferably 0.15 mm or more, more preferably 0.15 mm to 0.00. 25 mm. If it is lower than the range of the present invention, printing durability is not obtained, and if it is higher, paper separation is poor and the dot gain of the printed matter deteriorates, which is not preferable.

  The blanket having a compression value used in the printing method of the planographic printing plate of the present invention may be prepared using any of rubber material, cloth layer, compression layer, etc., and is generally sold. You can use things. For example, it is possible to easily obtain a blanket having a compression value used in the printing method of the present invention from physical property data of a blanket that is generally sold. For example, blankets # 5200-4 and # 4000 manufactured by DAY are available. -4, # 8889, # 8891, etc. can be used.

  Next, the scratch strength of the photosensitive layer of the planographic printing plate used in the printing method of the present invention will be described. As a method for measuring the scratch strength of the lithographic printing plate of the present invention, first, 120 mj was used using a thermal output machine (Image Setter PT-R4000 (Dai Nippon Screen Manufacturing Co., Ltd., oscillation wavelength 830 nm, output 100 mW)). After performing exposure at an exposure amount of 30 ° C., a processor PD-912-M (manufactured by Dainippon Screen Mfg. Co., Ltd.) is used for processing at 30 ° C. for 15 seconds to form an image portion. Using a HEIDON-18 type continuous load type scratch strength tester manufactured by Shinto Kagaku Co., Ltd. for the image portion, a tip angle of 60 with a diamond needle of 200 microns according to the test method of ISO 12137-2: 1997. For the film strength of the image area when the load is changed using a °, the weight of scratches on the film due to the load is shown. In particular, when the scratch strength is 150 g or less, a great effect can be obtained by using the printing method of the present invention. The lithographic printing plate having the photopolymerizable photosensitive layer of the present invention will be described below.

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

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

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

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

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

The above general formula will be described in more detail. As the linking group for Z ₁ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₅ ) —, —C (O) —O—, —C (R ₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, and a group represented by the following chemical formula 3 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 linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

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

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

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

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

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

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

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

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

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

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

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

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

  The sensitizing dye used in the photosensitive layer of the present invention sensitizes the decomposition of the photopolymerization initiator in the near infrared to infrared wavelength region of 750 nm or more, and various cationic dyes, Merocyanine, coumarin, xanthene, thioxanthene, azo dye and the like can be used as the anionic dye and neutral dye having no charge. 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. Examples of particularly preferred sensitizing dyes are shown below.

The content of the sensitizing dye is suitably about 1 to 300 mg per 1 m ² of the photosensitive layer. Preferably it is 10-100 mg / m < ² >.

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

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

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

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

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

In the formula, Z ₂ represents a linking group, and R 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.

Further details will be described. As the linking group for Z ₂ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₂₅ ) —, —C (O) —O—, —C (R ₂₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₂₅ and R ₂₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

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

Among the compounds represented by the formula 19, there are preferable compounds. That is, R 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 having 2-10. Specific examples of the compound represented by Chemical Formula 19 are shown below, but are not limited to these examples.

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

  The photosensitive layer of the present invention preferably contains a colorant. It is used for improving the visibility of the image area, and more preferably has absorption in the visible light region in order to improve the safelight property. Examples of these colorants include inorganic pigments, organic pigments, and dyes as described below.

  Examples of inorganic pigments include mica-like iron oxide, red lead, yellow lead, silver vermilion, ultramarine, titanium dioxide, coated mica, stone team chromate, titanium yellow, zinc chromate, molybdenum red, chromium oxide, calcium leadate, and the like. . Organic pigments include carbon black, phthalocyanine pigment, monoazo pigment, disazo pigment, condensed azo pigment, isoindolinone pigment, quinophthalone pigment, nickel azo pigment, perinone pigment, perylene pigment, anthrone pigment, quinacridone pigment, anthraquinone pigment, Examples thereof include thioindigo pigments, dioxazine pigments, indanthrone pigments, and pyranthrone pigments. Examples of the dye include various dyes such as a phthalocyanine dye, a triarylmethane dye, an anthraquinone dye, and an azo dye.

  The above pigments and dyes may be used alone, or two or more of them may be used in combination.

  The pigment is preferably added to the photosensitive layer of the lithographic printing plate in a state dispersed in an organic solvent by a disperser such as a paint conditioner, a ball mill, a jet mill, or a homogenizer, and the dye is added in a state dissolved in the organic solvent. It is 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 parts by mass with respect to 100 parts by mass of the polymer.

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

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

  The support on which the photosensitive layer of the present invention can be applied is a dimensionally stable plate-like material, such as paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), metal plate ( For example, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal Etc.), and paper or plastic film on which the above metal is laminated or vapor-deposited.

  A preferable support includes a polyester film or an aluminum plate, and among them, an aluminum plate having good dimensional stability and relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The total content of foreign elements in the alloy is 10% by weight or less. Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements. Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used as a support in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

  Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, an alkaline aqueous solution or the like is performed to remove the rolling oil on the surface, if desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used.

  The roughened aluminum plate is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodization treatment to enhance the water retention and wear resistance of the surface as desired. As an electrolyte used for anodizing treatment of an aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid or a mixed acid thereof is used. . The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

The treatment conditions for anodization vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by weight solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are suitable. When the amount of the anodic oxide coating is less than 1.0 g / m ² , the film resistance is insufficient, or the non-image area is easily damaged, particularly in the case of a lithographic printing original plate, So-called “scratch stains” to which ink adheres tend to occur.

  After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary. The hydrophilization treatment usable in the present invention is disclosed in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There is an alkali metal silicate (for example, sodium silicate aqueous solution) method. In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, it is disclosed in potassium zirconate fluoride disclosed in Japanese Patent Publication No. 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461, and 4,689,272. A method of treating with polyvinyl phosphonic acid as described above is used.

  The photosensitive layer of the negative lithographic printing plate of the present invention is preferably applied in a single layer in consideration of the production cost, and the thickness of the photosensitive layer is formed on the support with a dry thickness ranging from 0.5 μm to 10 μm. It is preferable that the thickness be in the range of 1 μm to 5 μm in order to greatly improve the printing durability. The photosensitive layer is coated and dried on the support using various known coating methods.

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

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

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

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

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

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

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

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

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

<Preparation of photosensitive lithographic printing plate>
A photosensitive composition liquid according to the following formulation was prepared. The photosensitive composition solution was applied on a grained and anodized aluminum plate having a thickness of 0.30 mm using a wire doctor coater, and dried to a thickness of 2.6 microns, followed by drying at 75 ° C. It was dried in a container for 7 minutes to produce a negative photosensitive lithographic printing plate.
<Coating liquid for photosensitive composition>
Polymer (P-1; mass average molecular weight of about 90,000) 10 parts by mass Photopolymerization initiator (BC-5) 2 parts by mass
(BS-1) 1 part by weight Ethylenically unsaturated compound (C-1) 5 parts by weight Sensitizing dye (S-33) 0.3 part by weight Polymerization inhibitor 2,6-di-t-butylcresol 0.1 Part by mass Solvent 1,3-dioxolane 70 parts by mass
20 parts by mass of cyclohexanone
Carbon black with an average particle size of 185 nm
0.1% by mass of 25% methyl ethyl ketone solution

Using the lithographic printing plate produced as described above, exposure was performed at an exposure amount of 120 mj using a thermal output machine (Image Setter PT-R4000 (Oscillation wavelength 830 nm, output 100 mW) manufactured by Dainippon Screen Mfg. Co., Ltd.). Thereafter, using a processor PD-912-M (manufactured by Dainippon Screen Co., Ltd.), processing was performed at 30 ° C. for 15 seconds with a developer having the following formulation. Subsequently, a gum solution having the following formulation was applied.
<Developer>
N-ethylethanolamine 37g
Phosphoric acid (85% solution) 10g
60g tetramethylammonium hydroxide (25% solution)
Alkyl naphthalenesulfonic acid Na (35% solution) 30 g
Diethylenetriaminepentaacetic acid 1g
1L with water
pH is 11.3 (25 ° C)
<Gum solution>
Phosphoric acid 1 potassium 20g
Gum arabic 30g
Sodium dehydroacetate 0.5g
EDTA2Na 1g
1L with water

  As a result of measuring the scratch strength of the solid image part of the lithographic printing plate produced as described above using HEIDON-18 manufactured by Shinto Kagaku Co., Ltd. with a diamond needle of 200 microns and a tip angle of 60 °, It was 60 g.

Four types of DAY blankets with different compression values, # N218-4, # 3000-4, # 4000-4, and # 5200-4, 100 N / cm by Shimadzu precision universal testing machine AG-IS series autograph a result of measuring the compression value at ² compression, # 218-4 blanket 0.10 mm (Comparative example 1), # 3000-4 blanket 0.12 mm (Comparative example 2), # 4000-4 blanket 0.16 mm (the Invention 1), # 5200-4 Blanket 0.20 mm (Invention 2).

  The lithographic printing plate produced as described above was used, and printing when each blanket was used was performed under the following printing conditions.

<Printing conditions>
Printing machine Heidelberg KORD (trademark of offset printing machine manufactured by Heidelberg), ink (New Champion ink H manufactured by Dainippon Ink Chemical Co., Ltd.), and commercially available PS plate moisturizer (ASTROMARK III Nikken Chemical Co., Ltd.) )), Printing was performed up to 100,000 sheets, and the performance of the printed matter was evaluated.

  From the above printing results, the blanket of Comparative Example 1 lacked small dots on 10,000 sheets and poor ink transfer on 30,000 sheets. Further, in the blanket of Comparative Example 2, the small halftone dots were lost on 30,000 sheets, and poor ink transfer occurred on 60,000 sheets. On the other hand, the blankets of the present inventions 1 and 2 could print up to 100,000 sheets without any problem. Therefore, the printing durability can be remarkably improved by the printing method of the planographic printing plate of the present invention.

Claims (3)

In the printing method of a lithographic printing plate having a photopolymerizable photosensitive layer, the lithographic printing characterized in that the blanket used for printing of the lithographic printing plate has a compression value of 0.15 mm or more when compressed at 100 N / cm ² How to print a plate.   The lithographic printing plate according to claim 1, wherein the lithographic printing plate is a lithographic printing plate having a photosensitive layer containing a sensitizing dye in a wavelength range of 380 nm to 1300 nm. How to print a plate.   The printing method according to claim 1 or 2, wherein the scratch strength of the photosensitive layer of the planographic printing plate is 150 g or less.