JP4315871B2 - Development method for photosensitive lithographic printing plate - Google Patents

Description

  The present invention relates to a development processing method for a negative photosensitive lithographic printing plate for a near infrared laser.

  Conventionally, a negative type lithographic printing plate using a diazo resin or the like is provided with a photosensitive layer on an aluminum plate which has been subjected to a silicate treatment in advance, and an alkaline developer having a relatively low pH (generally pH is 12 or less) after UV exposure. Development has been carried out. In such a processing method with a low pH developer, compared with a processing method with a high pH developer generally containing a silicate that is carried out in a positive type, alkali erosion of the image area during development is less likely to occur, As a printing plate, because it has good ink fillability and high printing durability, it has been actively used in newspaper printing, particularly where high printing durability is required, and in the business form printing field using ultraviolet curable ink.

  On the other hand, in recent years, computer-to-plate (CTP) technology has been developed to output directly on a printing plate without outputting it on film based on digital data created on a computer, and various types equipped with various lasers as output machines. Plate setters and photosensitive lithographic printing plates compatible with these have been actively developed. In particular, in an output device using a semiconductor laser or a YAG laser that emits light in the near infrared region of 750 nm or more, a high-power laser with a light source output of several hundreds mW to several watts is mounted, so the energy is extremely high. Image formation is possible. Such a photosensitive lithographic printing plate compatible with CTP cannot be used in the system using the above-mentioned conventional type diazo resin because the sensitivity is still insufficient. As an alternative system, for example, JP-A-7-20629 is disclosed. Potential acid generators, as described in JP-A-7-271029, JP-A-9-185160, JP-A-9-197671, JP-A-9-222731, JP-A-9-239945, JP-A-10-142780, etc. Of latent acid generators using the heat generated by photothermal conversion in the combination of UV and near-infrared absorbing dyes, and negative-type image formation using acid-catalyzed thermal crosslinking using the acid generated in this laser irradiation part A method is disclosed. Alternatively, as a system in which photon mode recording, which is an application of conventional high-sensitivity photopolymer technology, is applied to near-infrared light, for example, JP-A Nos. 2000-122274, 2000-131833, 2000-181559, 2000 No. 194124 discloses a negative type with high sensitivity by using various dyes that spectrally sensitize the photopolymerization initiator in near infrared light in a photopolymer system containing a photopolymerization initiator and an ethylenically unsaturated compound. Recording material is given.

  In particular, JP-A Nos. 2001-290271 (Patent Document 1), 2002-278066 (Patent Document 2), 2003-043687, 2003-29408, 2003-26744 and the like are polymerized in the side chain. Examples of printing plates that are compatible with CTP with high sensitivity and excellent printing durability by using a polymer having an ionic double bond in the photosensitive layer have been disclosed. A highly alkaline developer having a pH exceeding 12 described in JP-A-2002-278083 (Patent Document 3), 2002-278084 (Patent Document 4), 2002-278085 (Patent Document 5), etc. It has been done to use.

  In the various systems described above, when an aluminum plate subjected to silicate treatment is used as an aluminum support, as in the case of diazo resin, the adhesion between the photosensitive layer and the aluminum support is poor, and development Since the image part that is the exposed part is lost during processing, or when printing is performed after development, there is a problem that printing durability is poor, so it is necessary to use an aluminum plate that is not subjected to silicate processing. There wasn't.

  The silicate treatment on the aluminum surface is a treatment that is essential for improving the water retention of the non-image area in offset printing and preventing the occurrence of background stains, so use an aluminum plate that has been subjected to silicate treatment in advance. It was extremely preferable conditions for the printing plate. However, for various photosensitive lithographic printing plates conforming to conventional CTP, such a silicate-treated aluminum plate cannot be used for the above-mentioned reasons, and therefore, silicate treatment is performed during development. A silicate was introduced into the developer, which required a development process at a high pH. Accordingly, as a detrimental problem, there are problems in ink fillability and printing durability, and problems such as being unsuitable for printing using ultraviolet curable ink.

  As another problem when using a high pH developer, generally a developer having a pH of 12 or more has a problem that developability deteriorates because the pH decreases with time due to absorption of carbon dioxide in the atmosphere. In order to compensate for this, it was necessary to replenish the developer frequently. Furthermore, since the developer having such a high pH is extremely dangerous and harmful, special care must be taken in handling, storage and transportation.

On the other hand, when the photosensitive lithographic printing plate is treated with a developer having a pH of 12 or less, elution failure of the non-image area is likely to occur, and this causes scumming during printing. In particular, in order to increase sensitivity for near infrared laser exposure, a sensitizing dye for sensitizing to 750 nm or more, a polymer having a polymerizable double bond in the side chain, and two or more polymerizable double bonds The photosensitive layer containing the polymerizable monomer or oligomer has a high sensitivity, and the elution property tends to decrease with storage time. When a developing solution having a pH of 12 or less is used, the non-image area elution defect is more and more generated. .
JP 2001-290271 A JP 2002-278066 A JP 2002-278083 A JP 2002-278084 A JP 2002-278085 A

  Accordingly, an object of the present invention is to provide a processing method for improving printing durability and non-image area scumming even in the case of using a developer having a pH of 12 or less in a developing method for a near-infrared laser negative lithographic printing plate. There is.

The above object of the present invention has been basically achieved by the following invention.
After the silicate-treated on aluminum support positive pole oxidation polymer having a polymerizable double bond in a side chain, a monomer or oligomer having two or more polymerizable double bonds in the molecule, a photopolymerization initiator, and A method for developing a negative photosensitive lithographic printing plate for a near infrared laser having a photosensitive layer containing a sensitizing dye having absorption in a wavelength region of 750 nm or more, wherein a polymerizable double bond is formed on the side chain. it polymers having is a polymer having a vinylphenyl group in the side chain, said developer does not contains organic alkali metal silicate, containing tetraalkylammonium hydroxide, and the pH is 10 to 12 A development processing method of a photosensitive lithographic printing plate characterized by the above.

  According to the present invention, by setting the pH of the developer to 12 or less, the safety in handling is improved, and the printing durability and background stain of the planographic printing plate obtained by the development treatment can be improved at the same time.

  Hereinafter, the present invention will be described in detail. The photosensitive layer of the present invention contains at least a polymer having a polymerizable double bond in the side chain as a polymer. As a monomer for introducing a polymerizable double bond into the side chain of the polymer, for example, vinyl (meth) acrylate, vinyl (meth) acrylamide, allyl (meth) acrylate, allyl (meth) acrylamide, 1-propenyl- (Meth) acrylate, β-phenylvinyl- (meth) acrylate, α-chlorovinyl- (meth) acrylate, β-methoxyvinyl- (meth) acrylate, vinyl-thio- (meth) acrylate, and the following general formula Examples include monomers having a vinylphenyl group in the side chain as shown

  The polymer having a vinylphenyl group in the side chain is a polymer having a group represented by the following general formula in the side chain. In the present invention, a polymer having a vinylphenyl group in the side chain is particularly preferably used.

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, 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.
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.

  The polymer used in the present invention is preferably soluble in an alkaline aqueous solution, and is therefore particularly preferably a polymer containing a carboxyl group-containing monomer as a copolymerization component. In this case, the ratio of the monomer for imparting a polymerizable double bond to the side chain of the polymer is preferably 5% by mass to 95% by mass with respect to 100% by mass of the total composition of the polymer. 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 monoalkyl. Examples include esters, 4-carboxystyrene and the like.

  The polymer used in the present invention is synthesized as a multi-component copolymer by introducing other monomer components into the copolymer in addition to the monomer having a polymerizable double bond in the side chain and the monomer having a carboxyl group. Can also be used. 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, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, methacrylic acid alkyl esters such as dodecyl methacrylate, phenyl methacrylate, benzyl methacrylate, etc. Methacrylic acid aryl ester or alkyl aryl ester, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monomethacrylate Asteryl, methacrylic acid methoxypolyethylene glycol monoester, methacrylic acid ester having alkyleneoxy group such as methacrylic acid polypropylene glycol monoester, amino group-containing methacrylic acid ester such as 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate Or the same examples as the corresponding methacrylic acid esters as acrylic esters, or vinylphosphonic acid as a monomer having a phosphoric acid group, amino group-containing monomers such as allylamine and diallylamine, or vinylsulfonic acid And salts thereof, allylsulfonic acid and salts thereof, methallylsulfonic acid and salts thereof, styrenesulfonic acid and salts thereof, 2-acrylamido-2-methylpropanesulfonic acid and Monomers having a sulfonic acid group such as a salt of, monomers having a nitrogen-containing heterocycle such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, or monomers having a quaternary ammonium base 4-vinylbenzyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinyl Benzylpyridinium chloride, etc., or acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, dimethylacrylamide, diethylamine Acrylamide or methacrylamide derivatives such as chloramide, N-isopropylacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, Vinyl acetates such as vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, vinyl ethers such as methyl vinyl ether, butyl vinyl ether, others, N-vinyl pyrrolidone, acryloyl morpholine, tetrahydrofur Furyl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyl trimethoxysilane It may be used glycidyl methacrylate and various monomers as arbitrary copolymerization monomers. The proportion of these monomers in the copolymer may be introduced in any proportion as long as the proportion of the monomer having a polymerizable double bond in the side chain and the monomer having a carboxyl group is maintained. I can do it.

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

  The example of the polymer which has a vinylphenyl group in the side chain mentioned above is 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 monomer or oligomer having two or more polymerizable double bonds. 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 monomers or oligomers 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, 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, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pyrogallol triacrylate.

  A monomer or oligomer 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 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 having 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 polymer having a polymerizable double bond in the side chain.

  The photosensitive layer of the present invention preferably further contains a monofunctional polymerizable monomer. Examples of such compounds include vinyl monomers such as N-vinylpyrrolidone, N-vinylcaprolactam, vinylimidazole, and vinylpyridine; isobornyl (meth) acrylate, bornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, and dicyclo Pentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, Sopropyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate , Heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate , Dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate , Butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypolyethylene glycol (Meth) acrylate, methoxypolypropylene glycol (meth) acrylate, diacetone (meth) acrylamide, isobutoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, t-octyl (meth) acrylamide, dimethylaminoethyl (meta ) Acrylate, diethylaminoethyl (meth) acrylate, 7-amino-3,7-dimethyloctyl (meth) acrylate (Meth) acrylate monomers such as carbonate; N, N-diethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether, etc. .

  A compound having a thiadiazole and a vinylphenyl group can also be preferably used as the monofunctional polymerizable monomer. Such compounds are disclosed in Japanese Patent Application Laid-Open No. 2003-292535 and can be used with reference.

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

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

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

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

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

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

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

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

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

  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.

  In addition, various dyes and pigments are added as elements constituting the photosensitive layer for the purpose of enhancing the visibility of the image, and inorganic fine particles or organic fine particles are added for the purpose of preventing blocking of the photosensitive composition. This is also preferably done.

  The thickness of the photosensitive layer as a lithographic printing plate is preferably formed on an aluminum support with a dry thickness in the range of 0.5 to 10 microns, and more preferably in the range of 1 to 5 microns. It is extremely preferable to greatly improve the ratio. The photosensitive layer is coated and dried on the support using various known coating methods.

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

  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 with 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 dissolved amount of Al is 0.05 to 1.0 g / m ² . The other conditions are not particularly limited, but the alkali concentration is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and the alkali temperature is 20 to 100 ° C. It is preferable that it is, and it is more preferable that it is 30-50 degreeC. The alkali etching treatment is not limited to one method, and a plurality of steps can be combined. In the present invention, an alkali etching treatment can be performed after the mechanical roughening treatment and before the electrochemical roughening treatment. In this case, the dissolution amount of Al is preferably 0.05 to 30 g / m ² .

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

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

  The aluminum 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. 5 to 60 a / dm ^2, voltage 1 to 100 V, is suitably an electrolysis time of 10 to 200 seconds. Among these anodizing treatments, the method of anodizing at a high current density in a sulfuric acid electrolyte solution described in British Patent 1,412,768 is particularly preferable.

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

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

  The treatment liquid containing the alkali metal silicate preferably further contains an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide or lithium hydroxide. Among the alkali metal hydroxides, potassium hydroxide is preferable. Is preferred. The concentration of the alkali metal hydroxide in the treatment liquid is preferably in the range of 0.5 to 5% by mass, the pH of the treatment liquid at 25 ° C. is preferably 12 or more, more preferably in the range of 12 to 13.5, The range of 12.3 to 13.3 is particularly preferable.

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

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

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

  After the silicate treatment described above, a water washing treatment is performed. The method of washing with water is not particularly limited, and examples thereof include a spray method and a dipping method. These may be used alone or in combination, or may be used in combination of two or more. The time for the water washing treatment is not particularly limited.

  The photosensitive lithographic printing plate obtained by coating the photosensitive layer on the aluminum support produced as described above is subjected to scanning exposure with a near-infrared laser, and the exposed portion is cross-linked to become alkaline. Since the solubility in the developer is lowered, the pattern of the exposed image is formed by eluting the unexposed portion with an alkaline developer described later.

  The developer used in the present invention is a developer having a pH of 10 to 12 containing tetraalkylammonium hydroxide. The preferred pH of the developer is in the range of 11 to 11.8.

  As the alkyl group of the tetraalkylammonium hydroxide, an alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is particularly preferable. These alkyl groups may be further substituted with an alkoxy group such as a hydroxy group or a methoxy group.

  Specific examples of tetraalkyl ammonium hydroxide include tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetra n-propyl ammonium hydroxide, tetra n-butyl ammonium hydroxide, tetra n-hexyl ammonium hydroxide, tetrahydroxy hydroxide Examples include ethylammonium, trimethylhydroxyethylammonium hydroxide, methyltriethylammonium hydroxide, and methyltrihydroxyethylammonium hydroxide.

  The tetraalkylammonium hydroxide described above is preferably contained in the range of 1 to 40 g per liter of the developer, and particularly preferably in the range of 3 to 30 g.

  The pH of the developer is a pH at 25 ° C. In addition to the tetraalkylammonium hydroxide described above, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide are used in combination as an alkaline compound for adjusting the pH of the developer to the range of 10 to 12. can do. Potassium hydroxide is preferred when the alkali metal hydroxide is used in combination. When used in combination, the ratio of the tetraalkylammonium hydroxide to the total amount of the tetraalkylammonium hydroxide and the alkali metal hydroxide is preferably 20 mol% or more, more preferably 30 mol% or more, in molar ratio.

  The developer of the present invention preferably contains an alkanolamine such as monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine or N-ethylethanolamine. The combined use of tetraalkylammonium hydroxide and alkanolamine in the developer further improves the elution of the non-image area.

  The content of alkanolamine is preferably in the range of 5 to 100 g per liter of the developer, particularly preferably in the range of 10 to 60 g. The content ratio (mass ratio) of tetraalkylammonium hydroxide and alkanolamine in the developer is preferably in the range of 1: 1 to 1:10. The developer of the present invention preferably contains substantially no alkali metal silicate.

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

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

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
<Aluminum support>
A 0.24 mm thick aluminum plate that had been grained and anodized was subjected to a silicate treatment at 40 ° C. for 15 seconds with a treatment solution containing potassium silicate and potassium hydroxide. The SiO ₂ / K ₂ O molar ratio of this treatment liquid is 1.5. Immediately after the silicate treatment, it was washed with water and dried to obtain an aluminum support.

<Preparation of photosensitive lithographic printing plate 1>
The following photosensitive layer coating solution was applied onto the above aluminum support so that the dry thickness was 2.6 microns, and dried in a 75 ° C. drier for 7 minutes.
<Photosensitive layer coating solution>
Polymer (P-1; weight average molecular weight of about 90,000) 10 parts by weight Polymerizable double bond monomer (C-5) 3 parts by weight Monofunctional polymerizable monomer 1 part by weight
(Compound of formula 23 below)
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 mass cyclohexane 20 parts by mass

Samples prepared by forcibly heating the lithographic printing plate produced as described above at 50 ° C. for 6 days and unheated samples are prepared, and thermal output machines (images made by Dainippon Screen Mfg. Co., Ltd.) are prepared for each sample. After exposure using a setter PT-R4000 (oscillation wavelength 830 nm, output 100 mW), using a processor PD-912-M (Dainippon Screen Mfg. Co., Ltd.) A treatment at 28 ° C. for 20 seconds was performed, and then a gum solution having the following formulation was applied.
<Developer 1>
N-ethylethanolamine 37g
Phosphoric acid (85% solution) 10g
60g tetramethylammonium hydroxide (25% solution)
Alkyl naphthalenesulfonic acid Na (35% solution) 30 g
Diethylenetriaminepentaacetic acid 1g
1L with water
pH is 11.3 (25 ° C)
<Gum solution>
Phosphoric acid 1 potassium 20g
Gum arabic 30g
Sodium dehydroacetate 0.5g
EDTA2Na 1g
1L with water

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

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

The processing was performed in the same manner as in Example 1 except that the developing solution 1 of Example 1 was changed to the following developing solution 2, and printing evaluation was performed in the same manner.
<Developer 2>
N-ethylethanolamine 37g
Phosphoric acid (85% solution) 10g
24g tetramethylammonium hydroxide (25% solution)
5.5g potassium hydroxide
Alkyl naphthalenesulfonic acid Na (35% solution) 30 g
Diethylenetriaminepentaacetic acid 1g
1L with water
pH is 11.3 (25 ° C)

<Comparative Example 1>
In Example 1, treatment was performed in the same manner as in Example 1 except that tetramethylammonium hydroxide in Developer 1 was changed to sodium hydroxide (however, pH was 11.3), and printing evaluation was performed in the same manner.

<Comparative example 2>
In Example 1, except that potassium hydroxide was further added to Developer 1 to change the pH to 13, the same treatment as in Example 1 was carried out, and printing evaluation was carried out in the same manner.

<Comparative Example 3>
In Example 1, it processed similarly to Example 1 except not giving a silicate process at the time of manufacture of an aluminum support body, and evaluated printing similarly.

<Comparative example 4>
In Example 1, the polymer of the photosensitive layer coating solution was changed to a methyl methacrylate / methacrylic acid / methyl acrylate copolymer (copolymerization molar ratio 80/7/13; weight average molecular weight of about 50,000). Were processed in the same manner as in Example 1 and evaluated for printing in the same manner.

<Table 1>
─────────────────────────────
Unwarmed 50 ° C-Warmed for 6 days Sample Printing durability Dirt Printing durability Dirt ─────────────────────────────
Example 1 ○ ○ ○ ○
Example 2 ○ ○ ○ ○
Comparative Example 1 ○ △ ○ ×
Comparative Example 2 × ○ × ○
Comparative Example 3 ○ × ○ ×
Comparative Example 4 × ○ × ○
─────────────────────────────

Claims (1)

On a silicate-treated aluminum support after anodization, a polymer having a polymerizable double bond in the side chain, a monomer or oligomer having two or more polymerizable double bonds in the molecule, a photopolymerization initiator, and 750 nm A method for developing a negative photosensitive lithographic printing plate for a near infrared laser having a photosensitive layer containing a sensitizing dye having absorption in the above wavelength region, wherein the side chain has a polymerizable double bond polymer is a polymer having a vinylphenyl group in the side chain, said developer does not contains organic alkali metal silicate, that contain tetraalkylammonium hydroxide, and a pH of 10 to 12 A development method of a photosensitive lithographic printing plate characterized by the above.