JP4866250B2 - Processing method of lithographic printing plate - Google Patents

Description

  The present invention relates to a lithographic printing plate. More specifically, the present invention relates to a processing method of a lithographic printing plate capable of forming an image using a scanning exposure apparatus such as a laser based on a digital signal.

  In the photosensitive composition, the molecular structure undergoes a chemical change by a photoreaction, and as a result, a physical phenomenon (physical property) changes. This chemical change by the action of light includes cross-linking, polymerization, decomposition, depolymerization, functional group conversion, etc., and there are various such as solubility, adhesiveness, refractive index, substance permeability and phase change. Such photosensitive compositions have been put into practical use in a wide range of fields such as printing plates, resists, paints, coating agents, and color filters. Furthermore, it has been utilized and developed in the field of photoresist using photoengraving technology (photolithography). Photoresists utilize changes in solubility due to photoreactions, and more precise material design is required due to high resolution requirements.

  A widely used type of lithographic printing plate has a photosensitive coating applied to an aluminum base support. In this coating film, the exposed coating film portion is cured, and the unexposed coating film portion is eluted by the development process. Such a plate is called a negative printing plate. Lithographic printing utilizes the oleophilic and hydrophilic surface properties of the pattern formed on the surface of the printing plate and the background. In lithographic printing, ink and dampening water are simultaneously supplied to the printing plate on the printing press. The phenomenon of selectively transferring onto a pattern having a lipophilic surface is utilized. The ink transferred onto the pattern is then transferred to an intermediate body called a blanket, and further transferred to a printing paper for printing.

  Many studies have been made on a photosensitive composition that forms a relief image by utilizing the above-described change in solubility due to a photoreaction, and has been put into practical use. For example, a photosensitive composition containing a polymer having an unsaturated double bond in the side chain, a monomer or oligomer having an ethylenically unsaturated double bond, and a photopolymerization initiator is disclosed. (For example, patent document 1.) These have photosensitivity with respect to the short wavelength light centering on the ultraviolet region below 400 nm.

  A photosensitive composition using a polymer containing maleic anhydride as a copolymerization component is disclosed as a photosensitive composition utilizing a change in solubility due to a photoreaction at a wavelength of around 400 nm. (For example, Patent Documents 2 and 3) These have high surface hardness and excellent storage stability, and are suitable for protective films, interlayer insulating films, solder resist patterns, and the like. However, when used for a lithographic printing plate, good printability was not obtained.

  On the other hand, in recent years, with the advancement of image forming technology, a photosensitive material exhibiting high sensitivity to visible light has been demanded. For example, research on photosensitive materials and lithographic printing plates corresponding to output machines using an argon laser, a helium-neon laser, a red LED, and the like has been actively conducted.

  Furthermore, with the remarkable progress of semiconductor lasers, a near-infrared laser light source having a wavelength of 700 to 1300 nm can be easily used, and a photosensitive material and a lithographic printing plate corresponding to the laser light have attracted attention.

  As a composition having photosensitivity to near-infrared laser light of 750 to 900 nm, a combination of a specific polymer, a photoacid generator, and a near-infrared sensitizing dye is disclosed. (For example, Patent Document 4) However, it is difficult for a polymerizable composition using such a photoacid generator to impart sufficiently high photosensitivity in the near-infrared region, and particularly scanning exposure using various laser beams. Insufficient photosensitivity for application.

  A photosensitive composition comprising a polymer having a phenyl group substituted with a vinyl group in the side chain and a photo radical generator is disclosed. (For example, patent document 5.) In this invention, the lithographic printing plate which was highly sensitive with respect to the near infrared laser beam of 700-1300 nm and excellent in the printing durability of the exposure part can be obtained. However, when a lithographic printing plate after storage with time is processed using the developer disclosed in the present invention, the non-image area may be easily stained during printing due to poor elution. In order to maintain the printing durability of the exposed area while promoting the elution of the non-image area of a lithographic printing plate containing a polymer having a phenyl group substituted with a vinyl group, a developer added with a specific compound is disclosed. However, a sufficient effect could not be obtained for a lithographic printing plate after storage over time. (For example, Patent Document 6)

Therefore, there has been a demand for a processing method for a lithographic printing plate which is excellent in printing durability in an exposed area and elution in a non-image area even after a highly sensitive lithographic printing plate is stored over time.
Japanese Patent Publication No.59-46643 Japanese Patent Laid-Open No. 2-97502 JP 2005-331610 A JP-A-11-212252 Japanese Patent No. 3654422 JP 2002-278085 A

  An object of the present invention is to provide a processing method for a lithographic printing plate which is excellent in printing durability in an exposed area and elution in a non-image area even after a highly sensitive lithographic printing plate is stored over time.

  The above object of the present invention is a polymer containing, on a support, at least methacrylic acid and a component having a phenyl group with a vinyl group substituted on the side chain, and the polymer does not contain acrylic acid or acrylic. A lithographic printing plate having a photosensitive layer containing a polymer having a molar ratio of acid to methacrylic acid of 0.5 or less is processed with a developer containing at least one compound represented by the following general formula (I). Achieved by doing.

In the general formula (I), X represents a group selected from an unsubstituted or substituted phenyl group, naphthyl group, and pyridyl group , and L is composed of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. , A represents an alkylene group having 1 or more carbon atoms, l is 0 or 1, m represents an integer of 1 to 5 , and n represents 1 It represents the above integer.

  According to the present invention, it is possible to obtain a processing method for a lithographic printing plate that is excellent in printing durability in an exposed area and elution in a non-image area even after a highly sensitive lithographic printing plate is stored over time.

  Hereinafter, the present invention will be described in detail. The polymer used in the present invention is a polymer containing at least methacrylic acid and a component having a phenyl group substituted with a vinyl group in the side chain, and the polymer does not contain acrylic acid or acrylic acid methacrylic acid. The molar ratio with respect to the acid is 0.5 or less. The molar ratio of acrylic acid to methacrylic acid is more preferably 0.3 or less. By having a phenyl group substituted with a vinyl group in the side chain, it effectively cross-links by recombination of styryl radicals generated by the generated radicals, so a photosensitive material that does not require heat treatment is produced. be able to. However, by introducing a phenyl group into the polymer, the elution into the developer is lowered. By introducing acrylic acid into the polymer, the elution into the developer is improved. However, if the molar ratio of acrylic acid to methacrylic acid exceeds the range of the present invention, a lithographic printing plate having a relatively short number of days is developed. When processed, excellent printing durability of exposed areas and elution of non-exposed areas are obtained, but development changes greatly depending on the conditions over time, printing durability of exposed areas and elution of non-image areas It becomes difficult to maintain the balance.

  The phenyl group that the polymer used in the present invention has in the side chain may be substituted with a group or atom that can be substituted for the hydrogen atom of the phenyl group, and the polymer that is used in the present invention has a side chain. The vinyl group may be substituted with a halogen atom, a carboxy group, a sulfo group, a nitro group, a cyano group, an amide group, an amino group, an alkyl group, 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 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 ₁₄ represents a group or an atom that can be substituted with a hydrogen atom. n ₁ represents 0 to ₁ , m ₁ represents an integer of 0 to 4, and k ₁ represents an integer of ₁ to 4.

The above groups will be described in more detail. The linking group Z ₁ preferably contains a heterocyclic ring, and other groups and atoms such as oxygen atom, sulfur atom, alkylene group, alkenylene group, arylene group, —N (R ₁₅ ) —, —C (O) —. O—, —C (R ₁₆ ) ═N—, —C (O) —, a sulfonyl group, a group shown below, and the like may be contained singly or in combination of two or more. Here, R ₁₅ and R ₁₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom. By having a phenyl group substituted with a vinyl group in a side chain via a linking group containing a heterocyclic ring, the plate surface is strengthened by the interaction between the heterocyclic rings, and the printing durability is improved.

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

Among the groups that the polymer of the present invention has in the side chain, 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.). k ₁ is preferably 1 or 2.

  The polymer having a group as shown in the above example contains acrylic acid and methacrylic acid as a copolymer component in a molar ratio not exceeding the range of the present invention in order to impart solubility to the alkaline aqueous solution. The proportion of phenyl groups in which vinyl groups are substituted on the side chain in the copolymer composition is preferably 1% by mass or more and 95% by mass or less in 100% by mass of the composition of the whole polymer. The effect of the introduction may not be recognized. Further, when it is contained in an amount of 95% by mass or more, the copolymer may not be dissolved in the alkaline aqueous solution. Furthermore, the ratio of acrylic acid and methacrylic acid in the copolymer is preferably 5% by mass or more and 99% by mass or less, and the copolymer may not be dissolved in the alkaline aqueous solution at a ratio below this.

  In addition to acrylic acid and methacrylic acid, other monomer components may be introduced into the copolymer and synthesized and used as a multi-component copolymer. In such cases, monomers that can be incorporated into the copolymer include styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene, and 4-methoxystyrene. Styrene derivatives such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 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 and 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, tetrahydrofluor 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 can be introduced in any proportion as long as the preferred proportion of acrylic acid and methacrylic acid in the copolymer composition described above is maintained. .

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

  Examples of the polymer used in the present invention are shown below. In the formula, the number represents the mol% of each repeating unit in the total copolymer composition.

  The developer used in the present invention is characterized by containing at least one compound represented by the following general formula (I). A polymer containing at least methacrylic acid and a component having a phenyl group substituted with a vinyl group on the side chain, and the polymer does not contain acrylic acid, or the molar ratio of acrylic acid to methacrylic acid is 0.5 or less When a polymer is used, the solubility in an alkaline aqueous solution is low, and the lithographic printing plate having a photosensitive layer containing the polymer tends to further decrease the solubility in an alkaline aqueous solution depending on the storage conditions over time. It was. The lithographic printing is excellent in the printing durability of the exposed area and the elution of the non-exposed area, even when using a lithographic printing plate after storage by processing with a developer to which the compound of the general formula (I) is added. Made it possible to get a plate processing method.

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

  The content of the compound of the above general formula (I) contained in the developer is 0.001 to 10% by mass, particularly preferably 0.05 to 5% by mass, based on the total mass of the developer.

  The developer of the present invention is alkaline and the pH is in the range of 10 to 13.5, but is preferably in the range of 10.5 to 12.5. In the developer of the present invention, an aqueous developer in which an alkaline compound such as sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide and the like is dissolved together with the above compound favorably dissolves an unexposed portion selectively. This is extremely preferable because the surface of the support can be exposed.

  The developer of the present invention preferably contains an alkanolamine as an eluent in addition to the compound of the following general formula (I), and the content of the alkanolamine contained in the developer is represented by the general formula (I) The content of the compound is preferably in a range of 0.1 to 20 parts by mass with respect to 1 part by mass, and a particularly preferable range is between 1 to 10 parts by mass. Preferred alkanolamines are compounds represented by the following general formula (II).

In the formula, R ₂₁ represents an alkyl group having 1 to 10 carbon atoms. R ₂₂ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and the alkyl group may have a hydrophilic substituent such as a hydroxyl group, a carboxylic acid group, or a sulfonic acid group. R ₂₁ and R ₂₂ preferably have 1 to 6 carbon atoms. P ₂₁ and P ₂₂ represent an integer of 2 or more and may be the same or different. A preferred range of P ₂₁ and P ₂₂ is 2-6.

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

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

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

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

  In the processing method of the present invention, the processing is performed with a normal automatic processor after exposure. An automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for conveying a printing plate, each processing liquid tank and a spray tank, and is generally in a developing tank filled with the developing liquid. There is a method in which the printing plate is immersed and conveyed by a guide roll or the like, and a developing process is carried out. In addition, a developing solution assembled by a pump is sprayed from a spray nozzle and developed. Such an automatic developer can be processed while replenishing the replenisher according to the development processing amount, operating time, and the like.

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

  A photopolymerization initiator is preferably used for the photosensitive layer of the lithographic printing plate according to the present invention, and an organic boron salt is particularly preferably used. More preferably, an organic boron salt and a trihaloalkyl-substituted compound (for example, an s-triazine compound, an oxadiazole derivative or a trihaloalkylsulfonyl compound as a trihaloalkyl-substituted nitrogen-containing heterocyclic compound) are used in combination.

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

In the formula, each of R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ 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 ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ 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, onium ions, and cationic sensitizing dyes. Onium salts include ammonium, sulfonium, iodonium and phosphonium compounds. When a salt of an alkali metal ion or onium compound and an organic boron anion is used, photosensitivity in the wavelength range of light absorbed by the dye is imparted by adding a sensitizing dye separately. Further, when an organic boron anion is contained as a counter anion of the cationic sensitizing dye, photosensitivity is imparted according to the absorption wavelength of the sensitizing dye. However, in the latter case, it is preferable to further contain an organic boron anion as a counter anion of the alkali metal or onium salt.

  One of the most preferred embodiments according to the present invention is a photosensitive composition containing an organic boron salt and a dye for sensitizing the organic boron salt. In this case, the organic boron salt is photosensitive in the wavelength region of 750 to 900 nm. For the first time, addition of a sensitizing dye exhibits photosensitivity to light in such a wavelength region. High sensitivity to light in the wavelength region of 750 to 900 nm can be obtained by containing an organic boron salt and a dye for sensitizing the photosensitive layer in the photosensitive layer, but depending on the conditions of storage over time, the dark reaction proceeds to the developer. The solubility of is greatly reduced. This problem can be solved by processing using a developer to which the compound of the general formula (I) is added.

  The organic boron salt used in the present invention 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.

  In the present invention, a trihaloalkyl-substituted compound can be used as a photopolymerization initiator that can be used with an organic boron salt to realize higher sensitivity and higher contrast. 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% by mass to 50% by mass with respect to the solid content of the entire photosensitive layer.

  The photosensitive composition of the present invention is very suitably used for scanning exposure using near infrared to infrared light, that is, laser light having a wavelength region of 750 to 900 nm. Cyanine, polymethine, squarylium dye, and the like can be used as the sensitizing dye used for sensitizing to the near infrared, and the following sensitizing dyes are preferably used.

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

  The lithographic printing plate of the present invention preferably contains a polyfunctional polymerizable monomer or oligomer polymerizable compound having two or more polymerizable double bonds in the molecule. The molecular weight of such a polymerizable compound is less than 10,000, preferably 5,000 or less. Examples of the compound include compounds having two or more polymerizable double bonds such as an acryloyl group, a methacryloyl group, and a phenyl group substituted with a vinyl group.

  Examples of the compound having an acryloyl group or a methacryloyl group as a polymerizable double bond include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol di (meth) acrylate. , Tetraethylene glycol di (meth) acrylate, trisacryloyloxyethyl isocyanurate, tripropylene glycol di (meth) acrylate, ethylene glycol glycerol tri (meth) acrylate, glycerol epoxy tri (meth) acrylate, trimethylolpropane tri (meth) Acrylate, trimethylolethane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipe Data pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pyrogallol triacrylate.

  When a polymerizable compound having two or more phenyl groups substituted with vinyl groups in the molecule is used, crosslinking is effectively performed by recombination of styryl radicals generated by the generated radicals. A negative photosensitive material that is not required can be produced. A compound having a phenyl group substituted with a vinyl 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 ₄₁ and R ₄₂ 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 having 1 to 4 carbon atoms, An alkoxy group having 1 to 4 carbon atoms or the like is represented. R ₄₃ is 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, an aryl group, an alkoxy group, an aryloxy group, and the like. It may be substituted with an alkyl group, amino group, aryl group, alkenyl group, carboxy group, sulfo group, hydroxy group or the like. R ₄₄ represents a group or an atom that can be substituted with a hydrogen atom. m2 represents an integer of 0 to 4, and k2 represents an integer of 2 or more. When m2 is 2 or more, R ₄₄ may be the same or different.

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 ₄₅ ) —, —C (O) —O—, —C (R ₄₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₄₅ and R ₄₆ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Furthermore, the above-described linking group may have a substituent such as an alkyl group, an aryl group, or a halogen atom.

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

Among the compounds represented by the above general formula, there are preferable compounds. That is, _R41 and _R42 are hydrogen atoms, _R43 is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and k2 is preferably a compound having 2 to 10. Although a specific example is shown below, it is not limited to these examples.

  The addition amount of the polymerizable compound described above is preferably included in the range of 0.01 to 10 parts by mass, and more preferably in the range of 0.05 to 1 part by mass with respect to 1 part by mass of the polymer. It is particularly preferred that

  In addition, polymerization accelerators such as amines, thiols, and disulfides, chain transfer catalysts, and the like can be added as polymerization accelerators. Specific examples include amines such as N-phenylglycine, triethanolamine, N, N-diethylaniline, and thiols described in US Pat. No. 4,414,312 and Japanese Patent Application Laid-Open No. 64-13144. Disulfides described in JP-A-2-29161, thiones described in U.S. Pat. No. 3,558,322 and JP-A 64-17048, and o- described in JP-A-2-291560. Examples include acylthiohydroxamate and N-alkoxypyridinethiones. The addition amount of the polymerization accelerator is preferably 0.1 to 5% by mass of the total solid content of the polymerization layer. If it is less than this range, the effect cannot be expected. On the other hand, if the amount is too large, the film quality of the polymerized layer tends to deteriorate.

  In the lithographic printing plate of the present invention, it is also preferable to add other components for various purposes in addition to the components described above. In particular, it is preferable to add various polymerization inhibitors for the purpose of preventing thermal polymerization or thermal crosslinking of styryl groups and improving long-term storage stability. As the polymerization inhibitor in this case, compounds having various phenolic hydroxyl groups such as hydroquinones, catechols, naphthols, and cresols, quinone compounds, and the like are preferably used, and hydroquinone is particularly preferably used. In this case, the polymerization inhibitor is preferably added in an amount 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 a lithographic printing plate for the purpose of enhancing image visibility, and inorganic fine particles or organic fine particles are added for the purpose of preventing blocking of the photosensitive composition. It is also preferably performed.

  Regarding the thickness of the photosensitive layer itself when used as a lithographic printing plate material, it is preferably formed on the support with a dry thickness in the range of 0.5 to 10 microns, and more preferably in the range of 1 to 5 microns. Is extremely preferable in order to greatly improve printing durability. The photosensitive layer is a polymer containing at least methacrylic acid and a component having a phenyl group substituted with a vinyl group on the side chain, and the polymer does not contain acrylic acid or has a molar ratio of acrylic acid to methacrylic acid. A photosensitive coating solution containing at least a polymer having a molecular weight of 0.5 or less is prepared, and coated and dried on a support using various known coating methods. As the support, for example, a film or polyethylene-coated paper may be used, but a more preferable support is an aluminum plate that is polished and has an anodized film.

  In order to use a material having a photosensitive layer formed on a support as described above as a printing plate, an alkaline developer is obtained by subjecting the exposed part to exposure or laser scanning exposure and crosslinking the exposed part. Therefore, pattern formation is performed by eluting unexposed portions with the above-described alkaline developer.

  Next, a polymer containing at least methacrylic acid and a component having a phenyl group substituted with a vinyl group on the side chain, the polymer does not contain acrylic acid, or the molar ratio of acrylic acid to methacrylic acid is 0. A synthesis example of a typical polymer compound having a molecular weight of 0.5 or less is shown below.

Synthesis Example 1 (Synthesis Example of Polymer P-1)
150 g of bismuthiol (2,5-dimercapto-1,3-4-thiadiazole) was suspended in 600 ml of methanol, and 101 g of triethylamine was gradually added while cooling to obtain a uniform solution. While maintaining at room temperature, 153 g of p-chloromethylstyrene (manufactured by Seimi Chemical Co., CMS-14) was added dropwise over 10 minutes, and stirring was further continued for 3 hours. The reaction product gradually precipitated. After stirring, the reaction product was transferred to an ice bath, the internal temperature was cooled to 10 ° C., and the product was separated by suction filtration. The compound shown below was obtained with a yield of 75% by washing with methanol and drying for one day in a vacuum dryer.

  Take 40 g of the above monomer in a 1-liter four-necked flask equipped with a stirrer, nitrogen inlet tube, thermometer, and reflux condenser, add 20 g of methacrylic acid, 200 ml of ethanol and 50 ml of distilled water, and stir 40 g of triethylamine on a water bath. Was added. Under nitrogen atmosphere, the internal temperature was heated to 70 ° C., and 1 g of azobisisobutyronitrile (AIBN) was added at this temperature to initiate polymerization. The mixture was heated and stirred for 6 hours, and then the polymerization system was cooled to room temperature. 100 g of 1,4-dioxane and 23 g of p-chloromethylstyrene were added to the polymer solution, and the stirring was continued for another 15 hours at room temperature. Thereafter, 80 to 90 g of concentrated hydrochloric acid (35 to 37% aqueous solution) was added, and after confirming that the pH of the system was 4 or less, the whole was transferred into 3 liters of distilled water. The precipitated polymer was separated by filtration, washed repeatedly with distilled water, and then dried for one day in a vacuum dryer. The target polymer was obtained with a yield of 90%. It was a polymer having a mass average molecular weight of 90,000 (in terms of polystyrene) by molecular weight measurement by gel permeation chromatography, and further supported by the analysis by proton NMR.

  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.

Example 1
Using an anodized aluminum plate having a graining treatment with a thickness of 0.24 mm, a photosensitive coating solution represented by the following prescription is applied thereon so that the dry thickness is 2.0 μm, Drying was performed in a dryer at 75 ° C. for 6 minutes.
<Photosensitive coating solution>
Polymer (P-1) 12 parts by mass polymerization initiator (BC-6) 1 part by mass polymerizable compound (C-5) 3 parts by mass sensitizing dye (S-1) 0.5 parts by mass dioxane 70 parts by mass cyclohexane 20 parts by mass

In order to examine the storage stability, a sample stored in a dryer adjusted to 80 ° C. and a relative humidity of 80% while changing the heating time from 0 to 1 week was used. The developing property was evaluated by immersing in the following developing solution at intervals of 1 second at a liquid temperature of 35 ° C. using the developing solution, and determining the minimum time during which the photosensitive layer coating could be eluted. Those having a short time and little change in heating are preferable. The results are shown in Table 1.
<Developer>
10 g of compound of general formula (I) (PG-1)
Potassium hydroxide 20g
Potassium silicate 20g
Surfactant (Perex NBL, manufactured by Kao Corporation) 60g
1L of water

In order to investigate printing durability, an outer drum type plate setter mounted with a 830 nm semiconductor laser, heated for one week at 80 ° C. and relative humidity of 80%, and PT-R4000 manufactured by Dainippon Screen Mfg. Co., Ltd. Was used, and the prepared sample was subjected to 50% flat screen exposure under the conditions of a drum rotation speed of 1000 rpm, a resolution of 2400 dpi, and a laser irradiation energy of 100 mJ / cm ² . After the exposure, development was performed with a developer using an automatic developing machine PD-1310 for PS plate manufactured by Dainippon Screen Mfg. Co., Ltd. as an automatic developing machine. A developer having the above composition was used. The developer temperature was 35 ° C., and the immersion time in the developer was 20 seconds.

  As for printing durability, Heidelberg TOK (trademark of Heidelberg's offset printing machine) is used as a printing machine, ink is BEST ONE black H (manufactured by T & KTOKA), and dampening water is Astro Mark III (Co., Ltd.). A 1% aqueous solution of a dampening solution manufactured by Nikken Chemical Laboratory Co., Ltd.) was used, and evaluation was performed with the number of images where an image portion was missing and printing was impossible. The printing durability was evaluated according to the following evaluation criteria, and the results obtained are shown in Table 1.

  Printing durability ○: 200,000 or more, ○ △: 100,000 to less than 200,000, Δ: 50,000 to less than 100,000, ×: less than 50,000

The sensitivity was evaluated as follows. The exposure amount on the printing plate was set to 100 mJ / cm ² , and the solid image was exposed through a gray scale. Thereafter, processing was performed with the developer. The developer temperature was 35 ° C., and the immersion time in the developer was about 20 seconds. Sensitivity was judged from the number of gray scale steps obtained. Table 1 shows the number of gray scale steps. The gray scale is an optical wedge with an optical density difference of 1/2 ^1/2 for each stage, and a higher level indicates that the sensitivity is twice as high. The obtained results are shown in Table 1.

(Example 2)
The test was performed in the same manner as in Example 1 except that PG-1 contained in the developer described in Example 1 was changed to PG-6. The results are shown in Table 1.

(Example 3)
The test was performed in the same manner as in Example 1 except that PG-1 contained in the developer described in Example 1 was changed to PG-15. The results are shown in Table 1.

Example 4
The test was performed in the same manner as in Example 1 except that the polymer P-1 contained in the photosensitive coating solution described in Example 1 was changed to P-2. The results are shown in Table 1.

(Example 5)
The test was performed in the same manner as in Example 1 except that the polymer P-1 contained in the photosensitive coating solution described in Example 1 was changed to P-5. The results are shown in Table 1.

(Comparative Example 1)
The test was performed in the same manner as in Example 1 except that a developer not using PG-1 contained in the developer described in Example 1 was used. The results are shown in Table 1. The sample heated for 1 week at 80 ° C. and 80% relative humidity had low elution properties, and a good image could not be obtained by development.

(Comparative Example 2)
The test was performed in the same manner as in Example 1 except that the polymer P-1 contained in the photosensitive coating solution described in Example 1 was changed to one having the following structure. The results are shown in Table 1. The sample heated for 1 week at 80 ° C. and 80% relative humidity had low elution properties, and a good image could not be obtained by development.

(Comparative Example 3)
A test was conducted in the same manner as in Example 1 except that the polymer P-1 contained in the photosensitive coating solution described in Example 1 was changed to one having the following structure. The results are shown in Table 1.

(Comparative Example 4)
The test was performed in the same manner as in Example 1 except that PG-1 contained in the developer described in Example 1 was changed to AA-1. The results are shown in Table 1.

(Comparative Example 5)
The test was performed in the same manner as in Example 1 except that PG-1 contained in the developer described in Example 1 was changed to one having the following structure. The results are shown in Table 1.

  As is apparent from the results in Table 1, according to the present invention, there is provided a processing method for a lithographic printing plate that is excellent in printing durability in an exposed area and elution in a non-image area even after a highly sensitive lithographic printing plate is stored over time. can get.

  As an application example of the present invention, use as a printing plate for lithographic printing can be mentioned. Since it has excellent storage stability with time and good printing durability, it is easy to handle and can be used for many printed materials.

Claims (2)

On the support, a polymer containing at least methacrylic acid and a component having a phenyl group substituted with a vinyl group on the side chain, the polymer not containing acrylic acid, or the molar ratio of acrylic acid to methacrylic acid A lithographic printing plate having a photosensitive layer containing a polymer having an A of 0.5 or less is processed using a developer containing at least one compound represented by the following general formula (I): Processing method for printing plates.

(In the general formula (I), X represents a group selected from a phenyl group having no substituent or a substituent , a naphthyl group, and a pyridyl group , and L is composed of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. Represents a linking group composed of atoms selected from the group of atoms represented, A represents an alkylene group having 1 or more carbon atoms, l is 0 or 1, m represents an integer of 1 to 5 , and n represents Represents an integer of 1 or more.)   The lithographic printing plate processing method according to claim 1, wherein the photosensitive layer further contains an organic boron salt and a sensitizing dye having an absorption at 750 nm to 900 nm capable of sensitizing the organic boron salt.