JP4339201B2 - Photosensitive composition - Google Patents

Description

  The present invention relates to a photosensitive composition, and further to a photosensitive lithographic printing plate material using the same. Specifically, the present invention relates to a photosensitive composition excellent in printing durability, storage stability and safelight property, a negative photosensitive lithographic printing material using the same, and a development processing method thereof.

  In recent years, laser light in the visible to infrared region has been developed in addition to conventional ultraviolet light (UV) as an exposure light source for photosensitive lithographic printing plates. In particular, solid-state lasers and semiconductor lasers that have a light emitting region from the near infrared to the infrared region are becoming more powerful and more compact, and a CTP (computer-to-plate) system that directly makes plates from digital data such as computers is promising. Development of scanning lithographic printing plates that are sensitive to external laser light has been actively conducted. As such a laser scanning exposure light source, a semiconductor laser that emits light particularly near 830 nm is preferably used because it operates stably at a high output. Conventionally, a heat-sensitive lithographic printing plate that uses such a high-power semiconductor laser, generates high heat by the action of a photothermal conversion dye in the laser irradiation portion, and uses an image forming method by heat has been used. Examples of such heat-sensitive negative lithographic printing plates include systems described in JP-A-7-20629, JP-A-7-271029, and the like.

  In such a heat-sensitive negative lithographic printing plate, the heat-sensitive layer needs to be subjected to a heat treatment called preheating in order to complete the chemical reaction of the irradiated portion after exposure and before development processing. Preheating consumes a large amount of power, and it is difficult to uniformly heat the entire plate, making it difficult to obtain stable print quality. Printing durability is poor at locations where heating by preheating is insufficient, and background staining occurs at locations where heating is excessive. However, as an advantage of the heat sensitive type, an image is not formed in proportion to the exposure amount, but image formation is performed at a high temperature equal to or higher than a certain threshold value by exposure. For this reason, image formation is not performed at a low exposure amount, fogging hardly occurs, and a very high contrast line image can be obtained.

  As already disclosed in Japanese Patent Application Laid-Open No. 2001-290271 (Patent Document 1) and the like, the present inventors have prepared a polymer having a phenyl group substituted with a vinyl group in the side chain, a photo radical generator, and a sensitizing dye. A photosensitive composition containing has been presented. By using such a photopolymerization composition, image formation by near infrared laser exposure can be obtained not by heat but by light exposure. This eliminates the need for a preheating step after exposure and before development processing. However, since an image is formed in proportion to the exposure amount, an image may be formed even with a low exposure amount, and there is a drawback that it is easy to cover.

  Since an image forming material using a dye sensitive to near-infrared light uses near-infrared light as an energy source, it can be handled under a white light or a yellow light. However, it is difficult to completely remove the influence of the photosensitive type that is likely to cause fogging at a low exposure amount, even if, for example, a filter dye described in JP-A-2003-233192 is used. Radicals are generated, and the elution property of the non-image area is deteriorated particularly during development.

  On the other hand, a method of using a radical scavenger as an antioxidant for the storage stability of a photosensitive composition has been disclosed as a conventional patent and technology, and the use of a hindered phenol compound is disclosed in JP-A-10-104835. No. 10-010742, No. 9-244243, No. 9-188585, and the like. In addition, the use of a hindered amine compound for the same purpose is described in JP-A-8-297364, JP-A-9-244233, JP-A-9-244234, JP-A-11-52575, JP-A-2000-214580, and the like. Has been.

  Further, for the storage stability of the photosensitive type, use of a hindered phenol compound as an antioxidant is disclosed in JP 2002-287340 A (reference document 2), and use of a hindered amine compound is disclosed in JP 2002-244288. No. (Reference 3). These gazettes describe that the elution property of the non-image area changes due to the storage over time, and as a result, background stains occur during printing.

  The problems of the safelight property and the storage stability are accompanied by a change in elution property during development of a non-image part other than the image part. Although the amount of radicals necessary for the photopolymerization reaction is not certain, a large amount of radicals are generated in an extremely short time by scanning exposure with a laser in the image portion. On the other hand, the amount of radicals generated by irradiation with safe light such as white light and yellow light is smaller than that during scanning exposure. When storage is stable, factors other than light, for example, dark reactions such as temperature and humidity during storage, continue for a very long time. In order to obtain a photosensitive lithographic printing plate having good printing durability and excellent storage stability and safelight properties, it is preferable that there is no influence other than radicals generated in large quantities by scanning exposure. It was difficult to resolve these simultaneously.

Conventionally, in order to prevent the occurrence of background stains during printing, a silicate is introduced into the developer to improve the water retention of the non-image area, and a development treatment at a pH of 12 or higher is required. there were. However, as a problem with a high pH developer, the pH decreases due to absorption of carbon dioxide in the atmosphere, and a large amount of replenisher is required to compensate for this. This developer is highly dangerous and harmful. For this reason, it is preferable to set the pH of the developer to 12 or less. However, the lower pH of the developer is more significantly affected by changes in elution during development of non-image areas due to safelight properties and storage stability. .
JP 2001-290271 A (1st to 4th terms) JP 2002-287340 A (first to fourth items) JP 2002-244288 A (1st to 4th terms)

  Accordingly, an object of the present invention is to provide a photosensitive composition having sufficient sensitivity and excellent in development stability and printing durability. Furthermore, it is providing the negative photosensitive lithographic printing material excellent in safelight property, and its development processing method.

The above object of the present invention has been basically achieved by the following invention.
(1) A polymer having a polymerizable double bond in a side chain and a carboxyl group-containing monomer as a copolymerization component, a photopolymerization initiator, and sensitization for sensitizing the photopolymerization initiator in a wavelength range of 380 nm to 1300 nm A photosensitive composition comprising an agent, a hindered phenol compound having two or more hindered phenol structures in the molecule, and a hindered amine compound.
(2) The photosensitive composition according to (1), further containing an ethylenically unsaturated compound.
(3) The photosensitive composition as described in said (1) whose said photoinitiator is an organic borate.
(4) The photosensitive composition as described in (1), (2) or (3) above, further containing a trihaloalkyl-substituted compound.
(5) The photosensitive composition according to (4), wherein the trihaloalkyl-substituted compound is a nitrogen-containing heterocyclic compound having a trihalomethyl group or a trihalomethylsulfonyl compound.
(6) The photosensitive composition as described in (1) above, wherein the sensitizer is a sensitizing dye having absorption at 750 nm or more.
(7) A negative photosensitive lithographic printing material using the photosensitive composition according to any one of (1) to (6) above.
(8) The photosensitive composition according to any one of the above (1) to (6) is coated on an aluminum plate treated with a treatment liquid containing an alkali metal silicate. Characteristic negative photosensitive lithographic printing material.
(9) The negative photosensitive lithographic printing material, wherein the negative photosensitive lithographic printing material according to (7) or (8) is developed with an aqueous developer having a pH in the range of 10 to 12. Processing method of plate material.

  According to the present invention, the negative photosensitive lithographic printing plate has sufficient sensitivity, and development stability and printing durability are improved. At the same time, the safe light property is improved.

  Hereinafter, the present invention will be described in detail. The present invention uses a hindered phenol compound having two or more hindered phenol structures in the molecule. The hindered phenol structure is a phenolic structural unit characterized by the presence of a sublime atomic group at the ortho position of the phenolic hydroxyl group. As the sublime atomic group, a branched alkyl group or a cycloalkyl group is generally convenient.

  Examples of hindered phenol compounds having two or more hindered phenol structures in the molecule are shown below. However, the present invention is not limited to these examples. In the present invention, examples of the hindered phenol compound having two or more hindered phenol structures include compounds represented by the following general formula.

In the formula, R ₁ represents a branched alkyl group or a cycloalkyl group, and R ₂ represents a hydrogen atom, an alkyl group, or an alkylidene group. L represents a linking group, and m represents an integer of 2 to 6.

The general formula will be further described. R ₁ represents a branched alkyl group or a cycloalkyl group, and examples of the branched alkyl group include a branched alkyl group having 3 to 8 carbon atoms such as a tert-butyl group and a tert-pentyl group. Examples of the alkyl group include a cyclohexyl group. R ₂ represents a hydrogen atom, an alkyl group or an alkylidene group. In the case of an alkyl group or an alkylidene group, those having 1 to 40 carbon atoms are preferred, and those having 1 to 18 carbon atoms are particularly preferred. Among R _2, a hydrogen atom is particularly preferable.

Examples of the linking group represented by L include —S—, —O—, —CO—, —SO—, —SO ₂ —, —NR ₃ , an aliphatic residue, an aromatic residue, and a heterocyclic residue. Or a combination thereof selected from a combination thereof, and R ₃ represents a hydrogen atom, an alkyl group or an aryl group.

The benzene ring of the hindered phenol structure represented by the general formula further has other substitutable atoms or groups such as halogen atoms (eg, chlorine atoms), hydroxyl groups, cyano groups, amino groups, substituted amino groups, aliphatic groups. A group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, and the like. In addition, the substituents substituted on the benzene ring of the hindered phenol structure may be connected to each other to form a ring, and in this case, a chroman ring may be formed. Substituents R ₁ of the benzene ring (ortho, 2-position) with respect to, preferably has an alkyl group or a cycloalkyl group having 1 to 8 carbon atoms in the 6-position.

  Examples of the organic residue include various chemicals for imparting to the compound characteristics such as crystallinity, solubility in organic solvents, predeed out property (surface diffusibility), and non predeed out property (non-diffusible). Examples include structures. Since the efficacy of the hindered phenol group is not lost by these structures, any organic residue can be used in the present invention.

  Specific examples of hindered phenol compounds having two or more hindered phenol structures in the molecule are given below, but the present invention is not limited thereto.

  There is a preferred range for the amount of hindered phenolic compounds having two or more hindered phenol structures in the molecule contained in the photosensitive composition, and the total amount of the hindered phenolic compound in 100 parts by weight of the photosensitive composition. Is preferably contained in the range of 0.01 to 50 parts by mass. Furthermore, it is more preferable that it is contained in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the total photosensitive composition.

  Specific examples of the hindered amine compound in the present invention include compounds having at least one structural unit shown below in the molecule.

In the formula, R ₁ , R ₂ , R ₃ and R ₄ represent a hydrogen atom, an alkyl group or an aryl group, and Z represents an atomic group necessary for constituting a nitrogen-containing alicyclic ring. Y represents a hydrogen atom, an alkyl group or an organic residue. One of R ₁ and R ₂ or R ₃ and R ₄ may be incorporated into Z to give a double bond. Preferred examples of R _{1 to} R ₄ are alkyl groups having 1 to 6 carbon atoms. Preferred nitrogen-containing alicyclic structures include piperidine, piperazine, morpholine, pyrrolidine, imidazolidine, oxazolidine, thiazolidine, selenazolidine, pyrroline, imidazoline, isoindoline, tetrahydroisoquinoline, tetrahydropyridine, dihydropyridine, dihydroisoquinoline, oxazoline, thiazoline, selenazoline, Examples include pyrrole. Particularly preferred examples are piperidine, piperazine and pyrrolidine. Particularly preferred examples of the hindered amine compound having the structural unit represented by the above general formula are shown below.

  There is a preferred range for the amount of the hindered amine compound contained in the photosensitive composition, and the hindered amine compound is contained in the range of 0.01 to 50 parts by mass in a total of 100 parts by mass of the photosensitive composition. It is preferable. Furthermore, it is more preferable that it is contained in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the total photosensitive composition.

  As a photoinitiator used for this invention, a well-known compound can be used as a photoinitiator. 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 Examples thereof include onium salts such as compounds, thio compounds, organic peroxides, iodonium salts, diazonium salts, and sulfonium salts. 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. As the organic boron salt, it is particularly preferable to use a compound having an organic boron anion represented by the following general formula.

In the formula, R ₅ , R ₆ , R ₇ and R ₈ may be the same or different and each represents an alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, cycloalkyl group or heterocyclic group. . Of these, it is particularly preferred that one of R ₁ , R ₂ , R ₃ and R ₄ is an alkyl group and the other substituent is an aryl group.

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

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

  The organic boron salt in this case is a salt containing the above-described organic boron anion, and alkali metal ions and onium compounds are preferably used as cations forming the salt. Particularly preferable examples of the onium salt with an organic boron anion include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts. Examples of particularly preferred organic boron salts are shown below.

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

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

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

  When the above-described trihaloalkyl-substituted compound is used in combination, the ratio to the organic boron salt is that the trihaloalkyl-substituted compound is included in the range of 0.1 to 50 parts by mass with respect to 1 part by mass of the organic boron salt. Is preferred.

  About the sensitizer concerning this invention, it sensitizes decomposition | disassembly of a photoinitiator in the wavelength range of 380 nm-1300 nm, and it is as various cationic dyes, anionic dyes, and neutral dyes without an electric charge. Merocyanine, coumarin, xanthene, thioxanthene, azo dyes and the like can be used. Among these, particularly preferable examples are dyes selected from cyanine, carbocyanine, hemicyanine, methine, polymethine, triarylmethane, indoline, azine, thiazine, xanthene, oxazine, acridine, rhodamine, and azamethine dyes as cationic dyes. It is. In combination with these cationic dyes, they are preferably used because of their particularly high sensitivity and excellent storage stability. Furthermore, in recent years, an output machine (plate setter) equipped with a violet semiconductor laser having an oscillation wavelength in the range of 380 to 410 nm has been developed. As a photosensitive system having high sensitivity corresponding to the output device, a system containing a pyrylium compound or a thiopyrylium compound as a sensitizer is preferable. Examples of preferred sensitizing dyes according to the present invention are shown below.

  In the present invention, it is preferable to impart sensitivity to light in the near infrared to infrared wavelength region of 750 nm or more. Examples of sensitizing dyes having absorption in such a wavelength region are shown below.

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

  In the present invention, a polymer having a polymerizable double bond in a side chain and a carboxyl group-containing monomer as a copolymerization component is used as a polymer binder. The polymer is preferably an alkali-soluble polymer. In this case, the proportion of the carboxyl group-containing monomer contained in the copolymer composition is preferably 5% by mass or more and 99% by mass or less in 100% by mass of the total composition. May not dissolve in the aqueous alkali solution. More preferably, the ratio of the carboxyl group-containing monomer contained in the copolymer composition is 10% by mass or more and 80% by mass or less, particularly 20% by mass or more and 70% by mass or less, in 100% by mass of the total composition. preferable. Further, the ratio of the monomer having a polymerizable double bond contained in the copolymer composition is preferably 1% by mass or more and 95% by mass or less, more preferably 10% by mass in 100% by mass of the total composition. The content is 80% by mass or less and particularly preferably 20% by mass or more and 75% by mass or less.

  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.

  As monomers in the case of introducing a polymerizable double bond into a 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 -Acrylates, vinyl-thio-methacrylates 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 the 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 general formula in the side chain.

In the formula, Z ₁ represents a linking group, and R ₁₁ , R ₁₂ , and R ₁₃ 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 ₁₅ ) —, —C (O) —O—, —C (R ₁₆ ) ═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 ₁₅ and R ₁₆ 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 side which has the phenyl group substituted by said vinyl group in a side chain is shown below, it is 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 ₁₁ and R ₁₂ are hydrogen atoms and R ₁₃ 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 the above general formula 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 , Alkyl methacrylates such as ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, etc., aryl methacrylates such as phenyl methacrylate, benzyl methacrylate, or alkylaryl Esters, 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 Monomers having nitrogen-containing heterocycles such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, etc., or 4-vinylbenzyltrimethylammonium chloride, acryloyloxyethyl as a monomer having a quaternary ammonium base 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-isopropylacrylamide , Acrylamide or methacrylamide derivatives such as diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate, vinyl chloroacetate , Vinyl esters such as vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, vinyl ethers such as methyl vinyl ether, butyl vinyl ether, etc., N-vinyl pyrrolidone, acryloylmorpholine, tetrahydrofurfuryl methacrylate, vinyl chloride, Various monomers such as vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, glycidyl methacrylate, etc. That.

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

  The photosensitive composition of the present invention preferably further contains an ethylenically unsaturated compound. By combining this, a higher sensitivity can be realized, and a lithographic printing plate 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 similarly used, but these can also be preferably used as ethylenically unsaturated compounds.

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

  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 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. Specific examples of the compound represented by the above general formula are shown below, but the invention is not limited to these examples.

  There is a preferred range regarding the proportion of the ethylenically unsaturated compound as described above in the photosensitive composition, and the ethylenically unsaturated compound is 1 to 60 parts by mass in 100 parts by mass of the total photosensitive composition. It is preferably included in the range, and more preferably in the range of 5 to 50 parts by mass.

  The photosensitive composition of the present invention is immediately cured by light irradiation without being affected by oxygen in the air, and becomes insoluble in the developer. Therefore, it is not necessary to provide an over layer on the photosensitive layer, and after exposure, There is also an advantage that development and printing can be performed satisfactorily without any heat treatment.

  A polymerization inhibitor can also be preferably added as another element constituting the photosensitive composition. For example, compounds such as quinone and phenol are preferably used, such as hydroquinone, benzoquinone, p-methoxyphenol, catechol, t-butylcatechol, 2-naphthol, and 2,6-di-t-butyl-p-cresol. Examples thereof include quinone compounds and phenol compounds, and N-nitrosophenylhydroxyamine salts (for example, salts of cerium, aluminum, ammonium, etc.) described in JP-A-6-161997 and JP-A-10-260529. The preferred proportion of these polymerization inhibitors and the aforementioned ethylenically unsaturated compounds is preferably used in the range of 0.001 to 0.1 parts by mass with respect to 1 part by mass of the ethylenically unsaturated compound.

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

  About the element which comprises the photosensitive composition, in addition to the above-mentioned element, other elements can be additionally contained for various purposes. For example, inorganic fine particles or organic fine particles are also preferably added for the purpose of preventing blocking of the photosensitive composition or improving the sharpness of an image after development.

  The above-described photosensitive composition of the present invention can be preferably applied as a photosensitive layer of a negative photosensitive lithographic printing plate. In this case, the photosensitive layer is preferably formed on the support with a dry thickness in the range of 0.5 to 10 microns, and further in the range of 1 to 5 microns greatly improves printing durability. In order to improve, it is very preferable. The photosensitive layer is coated and dried on the support using various known coating methods. Support materials include paper, synthetic paper, paper laminated with synthetic resin (eg, polyethylene, polypropylene, polystyrene), plastic film (eg, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate), metal plate (eg, aluminum) , Aluminum alloy, zinc, iron, copper), paper or plastic film on which these metals are laminated or vapor-deposited can be used. When the negative photosensitive composition is used for the production of a lithographic printing plate, preferred supports are an aluminum plate, a polyethylene terephthalate film, a polycarbonate film, paper, and synthetic paper. A composite sheet in which an aluminum sheet is laminated on a polyethylene terephthalate film is also preferable, but an aluminum plate is particularly preferable.

  The aluminum plate used for the negative photosensitive lithographic printing plate of the present invention will be described in detail. 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.

  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 component on the surface of the aluminum plate can be selected by appropriately selecting conditions such as the average particle size, maximum particle size, bristle diameter, density, and indentation pressure of the particles used as the abrasive. The average depth of the 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 plate.

  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 plate used in the present invention is preferably treated with a treatment solution containing an alkali metal silicate after anodizing. The concentration of the alkali metal silicate in the treatment liquid is preferably in the range of 0.5 to 10% by mass in terms of SiO ₂ , more preferably in the range of 0.8 to 8% by mass, and further 1 to 6% by mass. A range is preferred. As the alkali metal silicate, sodium silicate, potassium silicate, or lithium silicate is used, and potassium silicate is preferable.

The treatment liquid containing the alkali metal silicate may be added with an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide or lithium hydroxide to raise the pH of the treatment liquid to 12 to 13.5. preferable. Of the alkali metal hydroxides, potassium hydroxide 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, and further 1 A range of .0 to 2.5 is preferred.

  As a method of treating the aluminum plate with the treatment liquid containing the alkali metal silicate, immersion or spraying may be used. The temperature of the treatment liquid is suitably about 5 to 80 ° C., preferably less than 75 ° C., particularly preferably 65 ° C. or less. In the case of dipping, the dipping time is suitably about 1 to 60 seconds, preferably 3 to 50 seconds.

   Moreover, in this invention, it is preferable to perform a sealing process with water vapor | steam or hot water of 60 degreeC or more after the anodization and before the process with the process liquid containing the said alkali metal silicate. The sealing treatment conditions with water vapor or hot water can be performed according to a conventional method. By combining this sealing treatment and the treatment with the treatment solution containing the alkali metal silicate of the present invention, the adhesion between the aluminum plate and the photosensitive layer is further improved.

  The negative photosensitive lithographic printing plate obtained by coating the photosensitive layer on the aluminum plate produced as described above is subjected to inspection exposure with various lasers, and the exposed portion is crosslinked by crosslinking. 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.

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

  The pH of the developer preferably used in the present invention is 10 to 12, more preferably 11 to 11.8. The pH of the developer is a pH at 25 ° C. As alkaline compounds for adjusting the pH of the developer to a range of 10 to 12, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, water such as tetramethylammonium hydroxide and tetrabutylammonium hydroxide Examples include alkanolamines such as tetraalkylammonium oxide, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, and N-ethylethanolamine. Of these, alkanolamines are particularly preferable. The content of alkanolamine is preferably in the range of 5 to 100 g per liter of the developer, particularly preferably in the range of 10 to 60 g. 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.

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

Example 1
<Aluminum plate>
A 0.24 mm thick aluminum plate that had been grained and anodized was subjected to a sealing treatment with hot water at 90 ° C. for 30 seconds, and then a treatment with a potassium silicate solution. The processing conditions are shown below. In addition, although the following potassium silicate aqueous solution used by Tama Chemical Industry Co., Ltd. was used, SiO ₂ contained in the aqueous solution is 20% and KOH is 10%.

<Treatment conditions with treatment liquid containing alkali metal silicate>
20 parts of KOH was added to 150 parts of an aqueous potassium silicate solution, and the total was made 1000 parts with water. The SiO ₂ / K ₂ O molar ratio of this treatment liquid is 1.6. The pH is 12.8 at 25 ° C. The treatment liquid temperature and immersion time are 30 ° C.-20 seconds.

<Preparation of negative photosensitive lithographic printing plate for near infrared laser>
A photosensitive composition liquid having the following formulation was prepared, and the dry film thickness was 3.5 on the aluminum support subjected to graining treatment, anodizing treatment and silicic acid treatment having a thickness of 0.24 mm using a wire bar. A photosensitive lithographic printing material was prepared by coating to a thickness of micron.

<Photosensitive composition liquid>
Polymer (P-1; Weight average molecular weight of about 90,000) 10 parts by weight Ethylenically unsaturated compound (C-5) 2 parts by weight Photopolymerization initiator 1 (BC-6) 2 parts by weight Photopolymerization initiator 2 Table 1 Amounts listed Sensitizing dye (S-39) 0.4 parts by weight 10% phthalocyanine dispersion 0.5 parts by weight Compound A Amounts listed in Table 1 Compound B Amounts listed in Table 1 Dioxane 70 parts by weight Cyclohexane 20 parts by weight

  The photosensitive lithographic printing material was prepared by changing the photopolymerization initiator and the compounds A and B in the photosensitive composition liquid as shown in Table 1.

About the photosensitive lithographic printing material produced as described above, a laser is used at a drum rotation speed of 600 to 1000 rpm using an external drum type plate setter (Dainippon Screen Manufacturing Co., Ltd. PT-R4000) equipped with an 830 nm semiconductor laser. An exposure test was performed with various irradiation energies. After exposure, a PS plate automatic processor PD-912 manufactured by Dainippon Screen Mfg. Co., Ltd. was used as an automatic processor, and development was performed at a liquid temperature of 28 ° C. for 20 seconds using the following developer. After development, the minimum exposure energy required to form a resolution pattern clearly on the aluminum plate was determined as the sensitivity of the photosensitive lithographic printing material. The photosensitive lithographic printing materials 1 and 2 of the comparative example were 600 mJ / cm ² or more. The photosensitive lithographic printing material 3 of the comparative example and the photosensitive lithographic printing materials 4 to 11 of the present invention all showed high sensitivity of 200 to 300 mJ / cm ² .
<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)

<Table 1>
────────────────────────────────────────
Photosensitive lithographic photopolymerization compound compound printing material initiator 2 A B
────────────────────────────────────────
1 T-4 / 1 part by weight None None Comparative Example 2 T-4 / 1 part by weight HP-5 / 2 parts by weight None Comparative Example 3 T-4 / 1 part by weight None HA-8 / 2 parts by weight Comparative Example 4 T -4/1 part by weight HP-5 / 1 part by weight HA-8 / 1 part by weight The present invention 5 T-4 / 1 part by weight HP-4 / 1 part by weight HA-8 / 1 part by weight The present invention 6 T-4 / 1 part by mass HP-2 / 1 part by weight HA-8 / 1 part by weight The present invention 7 T-4 / 1 part by weight HP-5 / 1 part by weight HA-5 / 1 part by weight The present invention 8 T-4 / 1 Mass part HP-4 / 1 mass part HA-5 / 1 mass part The present invention 9 T-4 / 1 mass part HP-2 / 1 mass part HA-5 / 1 mass part Present invention 10 BS-1 / 1 mass part HP-5 / 1 mass part HA-8 / 1 mass part Invention 11 BS-1 / 1 mass part HP-4 / 1 mass part HA-8 / 1 mass part Invention ───────── ──────────────────────────────

  Furthermore, as a comparative example, the polymer of the composition of photosensitive lithographic printing material 4 in Table 1 is a phenol resin (Shonol BRM-565 manufactured by Showa Polymer Co., Ltd .; condensate of metacresol and formalin, average polymerization degree 21 to 29), or in exactly the same manner as the photosensitive lithographic printing material 4 except that it was replaced with a methyl methacrylate / methacrylic acid / methyl acrylate (80/7/13 mass ratio) copolymer (average mass molecular weight of about 60,000). Photosensitive lithographic printing materials 12 and 13 were prepared. A photosensitive lithographic printing material 14 was prepared in the same manner as the photosensitive lithographic printing material 4 except that HP-5 of the photosensitive lithographic printing material 4 was replaced with 2,6-di-t-butylcresol.

Regarding the photosensitive lithographic printing materials 12 and 13 for comparison, the sensitivity was determined in the same manner as described above, and both were 600 mJ / cm ² or more. The photosensitive lithographic printing material 14 of the comparative example
Had a high sensitivity of 200 mJ / cm ² or less.

  Next, the photosensitive lithographic printing materials 1 to 14 were heated and stored at 40 ° C. for 5 days, and then processed in the same manner while changing the development time at intervals of 5 seconds from 20 to 40 seconds. As a result, none of the photosensitive lithographic printing materials 2 to 14 showed any elution failure of the non-image area in any of the development processes for 20 to 40 seconds, but the printing plate of Comparative Example 1 was eluted by development for 25 seconds. A defect occurred.

Of the photosensitive lithographic printing materials produced in the above examples, the photosensitive lithographic printing materials 3 to 11 and 14 having a sensitivity of 200 to 300 mJ / cm ² are every 10 minutes under a yellow fluorescent lamp (illuminance of 200 lux). The plate was exposed to 60 minutes and then subjected to laser exposure and development (30 ° C.-30 seconds) in the same manner. The non-image area of these samples was observed with a 100-fold magnifier, and the maximum time during which no residual film was observed on the surface of the non-image area was defined as the safe light time. In addition, the photosensitive lithographic printing materials 1 to 14 were heated and stored at 40 ° C. for 10 days. Similarly, laser exposure, development processing (28 ° C.-20 seconds), and coating with a gum solution having the following formulation were carried out to make plates. The lithographic printing plate was subjected to a printing test using a normal offset printing machine to evaluate the presence or absence of scumming on the non-image area. The presence / absence of background stain was determined by whether or not the white background on the printed matter was stained with ink when printing was performed up to 1000 sheets from the start of printing. The results are summarized in Table 2.

<Gum solution>
Phosphoric acid 1 potassium 20g
Gum arabic 30g
Sodium dehydroacetate 0.5g
EDTA2Na 1g
1L with water

<Table 2>
────────────────────────────────────
Photosensitive Safelight Planographic printing material Time (minutes) Soil stain Remarks ─────────────────────────────────────
1 --- Yes Comparative Example 2-No Comparative Example 3 20 None Comparative Example 4 60 None Present Invention 5 50 None Present Invention 6 50 None Present Invention 7 60 None Present Invention 8 50 None Present Invention 9 50 None Present Invention 10 60 None Present invention 11 50 None Present invention 12 --- --- Comparative example 13 --- --- Comparative example 14 30 None Comparative example ------------------- ────────────
(-) In the table is not implemented because the sensitivity is 600 mJ / cm ² or more

  The printing durability was evaluated for the photosensitive lithographic printing materials 1 to 14 using a normal offset printing machine, ink, and fountain solution. The printing durability was evaluated based on the maximum number of printed sheets when a solid image, a 5% halftone dot, and a fine line image skipped. As a result, each of the light-sensitive materials (printing plates) 4 to 11 of the present invention was capable of printing 200,000 sheets, and Comparative Example 1 was capable of printing 200,000 sheets. The number of printing sheets for No. 14 and No. 14 was 150,000. The printing durability of Comparative Examples 12 and 13 was 50,000 or less.

  As a result, the lithographic printing plate of the present invention has high sensitivity, good printing durability, and excellent storage stability and safelight properties at the same time. On the other hand, the comparative lithographic printing plate 1 had good printing durability, but scumming occurred, and the safelight property and storage stability were insufficient. In Comparative Examples 2, 3, and 14, the occurrence of background stains after storage was good, but the safelight property and printing durability were not satisfactory. In Comparative Examples 12 and 13, the sensitivity and printing durability are insufficient.

  As is clear from the above examples, by using the photosensitive lithographic printing material of the present invention, a photosensitive lithographic printing material having sufficient sensitivity and excellent in development stability, printing durability and safelight property is obtained. Obtainable.

Claims (1)

  A polymer having a polymerizable double bond in the side chain and having a carboxyl group-containing monomer as a copolymerization component, a photopolymerization initiator, a sensitizer that sensitizes the photopolymerization initiator in a wavelength region of 380 nm to 1300 nm, and a molecule A photosensitive composition comprising a hindered phenol-based compound having two or more hindered phenol structures and a hindered amine-based compound.