JP5036586B2 - Photosensitive planographic printing plate - Google Patents

Description

  The present invention relates to a photosensitive lithographic printing plate material. More specifically, the present invention relates to a photosensitive lithographic printing plate suitable for drawing with near-infrared laser light, and more particularly to a photosensitive lithographic printing plate suitable for high-definition AM screen printing and FM screen printing having a screen line number of 200 lines or more.

  In recent years, computer-to-plate (CTP) technology has been developed to output directly on a printing plate without outputting it on film based on digital data created on a computer. Various plate setters equipped with various lasers as output machines The development of photosensitive lithographic printing plates suitable for these has been actively conducted. As such a laser scanning exposure light source, a semiconductor laser that emits light in the near infrared region of 900 nm or less is particularly preferred because it operates stably at a high output.

  As such a lithographic printing plate using a semiconductor laser that emits light in the near-infrared region of 900 nm or less, for example, a negative type using an image forming method by generating high heat by the action of a photothermal conversion dye in a laser irradiation part. Examples of the lithographic printing plate include JP-A-7-20629 (Patent Document 1) and JP-A-7-271029 (Patent Document 2). However, in such a negative type lithographic printing plate, after exposure, if it is necessary to heat-process the photosensitive layer and complete the chemical change of the laser irradiation part, or even if it is a type that does not require the heat treatment after exposure, Exposure with high energy is required, and not only does the exposure time become long and work efficiency deteriorates, but also the laser life is shortened and there is a problem in terms of cost, and high sensitivity of the lithographic printing plate is desired. Yes. On the other hand, as a photosensitive lithographic printing plate having high sensitivity to a semiconductor laser emitting in the near infrared of 900 nm or less, a technique using a polymer having a phenyl group substituted with a vinyl group in a side chain is disclosed in JP-A-2001. -290271 (Patent Document 3) discloses a technique using an onium salt, a photothermal conversion element, and a radical generator. JP-A-9-34110 (Patent Document 4) discloses a cationic absorption skeleton and an anionic absorption skeleton. Techniques using ionic dyes are disclosed in Japanese Patent Application Laid-Open No. 2000-075474 (Patent Document 5). However, such a high-sensitivity lithographic printing plate is linearly dependent on the amount of light and forms an image. Therefore, when exposed with laser light, the edge of the image depends on the shape of the energy distribution of the laser light, resulting in insufficient exposure. In addition, there is a problem in that an insufficiently polymerized portion is formed. Therefore, the sharpness of the image edge is impaired, resulting in a decrease in image quality, and the insufficiently polymerized image edge is difficult to uniformly develop, resulting in non-uniform image in the development process, This was a cause of variation in the halftone dot area. Further, the image end portion where the polymerization is insufficient causes a change in the image during printing, which causes poor printing durability.

  In order to reduce the energy distribution of the laser beam, mechanical measures are taken to reduce the laser beam diameter. However, the laser beam diameter can only reach the diffraction limit determined by the laser wavelength and the numerical aperture of the imaging lens. This limit value becomes smaller in proportion to the wavelength of the laser. Therefore, image formation with a long-wavelength laser such as a semiconductor laser that emits light in the near-infrared region is difficult to narrow down the beam diameter compared to image formation with a short-wavelength laser. However, there is a limit at present.

  In recent years, with the development of the CTP technology, the demand for FM screen printing and high-definition AM screen printing has increased. An FM (Frequency Modulation) screen is one in which minute halftone dots of about 20 μm are randomly arranged regardless of the screen angle and the number of lines, and the density gradation is expressed by the dot density per unit area. The features of this FM screen printed matter are that the color reproducibility of the printed matter looks vivid, no interference moire occurs, no tone jump occurs in the halftone part with a gentle gradation, and the amount of ink used can be reduced. Etc. Furthermore, the number of lines generally used in AM (Amplitude Modulation) screen printing is 175 lines or less per inch. However, in recent years, improvement of printing quality has been demanded, and high definition has been demanded. Printing is now required. In general, it is said that a screen using 200 or more screen lines is high definition. Features of high-definition printed materials include improved image texture and detail reproducibility.

  As described above, high quality printing is required for CTP printing, and accordingly, photosensitive lithographic printing plates are required to have higher image quality and higher image reproducibility than ever before. On the other hand, Japanese Patent Laid-Open No. 2006-66073 (Patent Document 6) discloses a technique for balancing sensitivity and image reproducibility by setting the absorbance (Abs) of the emission wavelength of the laser to be exposed to 0.4 or less. Japanese Patent Laid-Open No. 2005-148212 (Patent Document 7) discloses a technique for improving the image quality by adding a dye having absorption at the same wavelength as the laser wavelength exposed to a layer different from the photosensitive layer as an antihalation layer. However, both have insufficient printing durability and are not sufficient as plate materials suitable for high-definition AM screen printing and FM screen printing.

Unlike the addition of a dye to the antihalation layer, a technique for adding a desensitizing dye as a technique for adding a dye having absorption at a wavelength equivalent to the laser wavelength to be exposed to a single layer other than the sensitizing dye is disclosed in JP Japanese Patent Application Laid-Open No. 2005-292409 (Patent Document 8) discloses a technique for adding a banding inhibitor in Japanese Patent Application Laid-Open No. 2002-214776 (Patent Document 9). These techniques are also disclosed in high-definition AM screen printing and FM. Screen printing was insufficient because sufficient printing durability could not be secured. In addition, there are two types of methods of using phthalocyanine compounds conventionally known in the art: addition as a sensitizing dye and addition as a colorant for obtaining visibility. For example, the usage as a sensitizing dye is described in JP-A-9-134007 (Patent Document 10) and JP-A-2002-72466 (Patent Document 11). Moreover, as a coloring agent for obtaining visibility, it describes in Unexamined-Japanese-Patent No. 2001-183822 (patent document 12), Unexamined-Japanese-Patent No. 2002-251019 (patent document 13), etc., for example.
Japanese Patent Laid-Open No. 7-20629 Japanese Patent Laid-Open No. 7-271029 JP 2001-290271 A JP-A-9-34110 Japanese Unexamined Patent Publication No. 2000-075474 JP 2006-66073 A JP 2005-148212 A JP 2005-292409 A Japanese Patent Application Laid-Open No. 2002-214776 JP-A-9-134007 JP 2002-72466 A JP 2001-183822 A JP 2002-251019 A

  Accordingly, an object of the present invention is to provide high sensitivity, FM screen printing, and high-definition AM screen in a photosensitive lithographic printing plate exposed by a scanning exposure apparatus using a laser emitting in the near infrared region of 900 nm or less. A photosensitive lithographic printing plate having image quality suitable for printing and excellent printing durability is provided.

The above object of the present invention has been achieved by the following photosensitive lithographic printing plate.
1. Photosensitive lithographic printing plate having a photosensitive layer containing a polymerizable polymer, a photopolymerization initiator, and a sensitizing dye having an absorption maximum at 750 nm or more and less than 900 nm on the support, which can sensitize the photopolymerization initiator Wherein the photosensitive layer contains a phthalocyanine compound having an absorption maximum at 900 nm or more.
2. The photosensitive lithographic printing plate as described in 1 above, wherein the photopolymerization initiator is an organic boron salt.
3. The photosensitive lithographic printing plate as described in 1 or 2 above, wherein the polymerizable polymer is a polymer having a phenyl group substituted with a vinyl group in a side chain and a carboxyl group-containing monomer as a copolymerization component. .

  According to the present invention, a photosensitive lithographic printing plate exposed by a scanning exposure apparatus using a laser emitting light in the near-infrared region of 900 nm or less can be used for FM screen printing and high-definition AM screen printing with high sensitivity. A photosensitive lithographic printing plate having suitable image quality and excellent printing durability can be provided.

The present invention will be described in detail below.
A phthalocyanine compound having an absorption maximum at 900 nm or more, which is a blending component that is a feature of the present invention, will be described. The phthalocyanine compound is a compound composed of four isoindoles and four nitrogen atoms located at respective meso positions, and is represented by the following general formula (1). Among the phthalocyanine compounds, those having an absorption maximum at 900 nm or more are used in the present invention.

In the general formula (1), examples of the substituent represented by Y ¹ to Y ¹⁶ include a hydrogen atom, a halogen atom, a hydroxy group, an amino group, a nitrile group, a nitro group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted group. Substituted arylamino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkylthio group, substituted or unsubstituted arylthio group, substituted or unsubstituted alkyl group, substituted or unsubstituted Substituted aryl group, substituted or unsubstituted heteroaromatic group, substituted or unsubstituted alkylcarbonyl group, substituted or unsubstituted arylcarbonyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted aryloxycarbonyl Group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted aryl Minocarbonyl group, substituted or unsubstituted alkoxysulfonyl group, substituted or unsubstituted aryloxysulfonyl group, substituted or unsubstituted alkylsulfonyl group, substituted or unsubstituted arylsulfonyl group, substituted or unsubstituted N-alkylamino Sulfonyl group, substituted or unsubstituted N, N-dialkylaminosulfonyl group, substituted or unsubstituted N-arylaminosulfonyl group, substituted or unsubstituted N, N-diarylaminosulfonyl group, substituted or unsubstituted N- An alkyl-N-arylaminosulfonyl group, a substituted or unsubstituted alkylsulfinyl group, a substituted or unsubstituted arylsulfinyl group, two adjacent groups together, an N-alkylimide group, an N-arylimide group, Forms aromatic and heteroaromatic rings You may do it. Preferred substituents are those having a benzene ring or having a plurality of electron donating groups, such as a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkylthio group, A substituted or unsubstituted arylthio group;

M in the above general formula represents a metal, a metal oxide, a metal halide, or an atom other than a metal. Examples of the atom other than a metal include two hydrogen atoms. Examples of M being a divalent metal include Mg, Cu, Zn, Fe, Co, Ni, Ru, Pb, Rh, Pd, Pt, Mn, and Sn. the metal derivatives are, for example, AlF, AlCl, AlBr, AlI , InCl, FeCl, MnOH, SiCl 2, SnCl 2, GeCl 2, Si (OH) 2, Sn (OH) 2, Ge (OH) 2, VO, TiO etc. are mentioned. M is preferably a compound of AlCl, Mg, Co, Ni, Cu, Zn, VO, and TiO. Specific examples include ProJET900NP and ProJET925NP manufactured by FUJIFILM Imaging Colorant Co., Ltd., and YKR-3080, YKR-3081 and YKR-3090 manufactured by Yamamoto Kasei Co., Ltd.

  The absorption maximum of the phthalocyanine compound of the present invention is such that 0.1 part by mass of the phthalocyanine compound is dissolved in 10 parts by mass of 10% by mass of the polymerizable polymer used in the coating solution, and the dry film thickness is 100 μm of polyethylene terephthalate film. The absorption of the sample coated so as to be 1 μm can be measured, and can be determined by the difference from the comparative sample coated with the polymerizable polymer alone.

  The amount of the phthalocyanine compound used in the present invention varies slightly depending on the combination with the sensitizing dye, but it may be 1 to 300% by mass with respect to the sensitizing dye having an absorption at about 750 nm to less than 900 nm. preferable.

  The polymerizable polymer used in the present invention is not particularly limited, but a polymer having a polymerizable double bond is preferably used. The method for introducing a polymerizable double bond into the side chain is not particularly limited, and various conventionally known methods can be used. For example, allyl acrylate, allyl methacrylate, vinyl acrylate, vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, β-phenyl vinyl methacrylate, vinyl acrylamide, vinyl methacrylamide, α-chlorovinyl acrylate, α-chlorovinyl methacrylate, β Examples thereof include polymerizable polymers containing a monomer having a polymerizable double bond such as methoxyvinyl acrylate, β-methoxyvinyl methacrylate, vinyl thioacrylate and vinyl thiomethacrylate as a copolymerization component. More preferably, it is a polymerizable polymer having a phenyl group substituted with a vinyl group in the side chain so that the styryl radicals generated by the generated radicals can be regenerated by having a phenyl group substituted with a vinyl group in the side chain. Since cross-linking is effectively performed by bonding, a highly sensitive lithographic printing plate is obtained. However, while the sensitivity is high, image quality is particularly problematic when plate making of high-definition AM screens or FM screen images is performed.

  The polymer having a vinylphenyl group in the side chain is one in which the phenyl group is bonded to the main chain directly or via a linking group, and the linking group is not particularly limited, and any group, atom or their group can be used. A complex group may be mentioned. The phenyl group may be substituted with a substitutable group or atom other than a vinyl group, and the vinyl group is a halogen atom, a carboxyl 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 may be substituted. More specifically, the polymer having a vinylphenyl group in the side chain described above has a group represented by the following general formula (2) in the side chain.

In the formula, Z ₁₁ represents a linking group, and R ₁₁ , R ₁₂ and R ₁₃ are a hydrogen atom, a halogen atom, a carboxyl 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 carboxyl group, a sulfo group, a hydroxy group, or the like. R ₁₄ represents a group or an atom capable of substituting for a hydrogen atom. n ₁₁ represents 0 or 1, m ₁₁ represents an integer of 0 to 4, k ₁₁ represents an integer of 1-4.

The general formula (2) will be described in more detail. As the linking group for Z ₁₁ , 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 example of group represented by the said General formula (2) is shown below, it is not limited to these examples.

Among the groups represented by the general formula (2), 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 Z ₁₁ , those containing a heterocyclic ring are preferred, and those wherein k ₁₁ is 1 or 2 are preferred.

  As a ratio of the monomer having a vinylphenyl group in the side chain in the polymer having a vinylphenyl group in the side chain as shown in the above example, 1% by mass or more and 95% by mass in 100% by mass of the composition of the whole polymer. % Or less, and if it is less than 1% by mass, the introduction effect may not be recognized. In addition, when the content exceeds 95% by mass, the polymer may not be eluted into the developer when used in a lithographic printing plate.

  The polymerizable polymer of the present invention preferably contains a carboxyl group-containing monomer as a copolymer component in order to impart solubility to an alkaline aqueous solution. The proportion of the carboxyl group-containing monomer in the polymer is preferably 5% by mass or more and 99% by mass or less, and if it is less than 5% by mass, the copolymer may not be dissolved in the alkaline aqueous solution. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, 4-carboxystyrene, and the like.

  As the polymerizable polymer used in the photosensitive layer of the present invention, it is also preferable to use a multi-component copolymer into which other monomer components other than the carboxyl group-containing monomer are introduced. As monomers that can be incorporated into the copolymer in such cases, styrene derivatives such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetoxystyrene, 4-aminostyrene, chloromethylstyrene, 4-methoxystyrene, Methyl methacrylate such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, etc., aryl methacrylate such as phenyl methacrylate, benzyl methacrylate, etc. Esters or alkylaryl esters, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monoester methacrylate, methacrylate Methacrylic acid esters having an alkyleneoxy group such as acid methoxypolyethylene glycol monoester and methacrylic acid polypropylene glycol monoester, and amino group-containing methacrylic acid esters such as methacrylic acid-2-dimethylaminoethyl and methacrylic acid-2-diethylaminoethyl Or examples similar to the corresponding methacrylic acid ester as an acrylate ester, vinylphosphonic acid or the like as a monomer having a phosphoric acid group, amino group-containing monomers such as allylamine or diallylamine, or vinylsulfonic acid and Such salts, allyl sulfonic acid and its salt, methallyl sulfonic acid and its salt, styrene sulfonic acid and its salt, 2-acrylamido-2-methylpropane sulfonic acid and its salt, etc. Monomers having an acid group, monomers having a nitrogen-containing heterocyclic ring such as 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N-vinylcarbazole, or 4-vinyl as a monomer having a quaternary ammonium base Benzyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, quaternized product of dimethylaminopropylacrylamide with methyl chloride, quaternized product of N-vinylimidazole with methyl chloride, 4-vinylbenzylpyridinium chloride, etc. Or acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, dimethylacrylamide, diethylacrylamide, Acrylamide or methacrylamide derivatives such as N-isopropylacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-hydroxyphenyl acrylamide, acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate , Vinyl esters such as vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, etc., vinyl ethers such as methyl vinyl ether, butyl vinyl ether, others, N-vinyl pyrrolidone, acryloyl morpholine, tetrahydrofurfuryl methacrylate , Vinyl chloride, vinylidene chloride, allyl alcohol, vinyl trimethoxysilane, glycidyl meta Can be used Relate such various monomers as arbitrary copolymerization monomers. The proportion of these monomers in the copolymer may be introduced in any proportion as long as the preferred proportion of the carboxyl group-containing monomer in the copolymer composition described above is maintained. it can.

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

  Examples of preferred polymerizable polymers of the present invention are shown below. In the formula, the number represents the mass% of each repeating unit in the copolymer total composition of 100 mass%.

  The sensitizing dye having an absorption maximum at 750 nm or more and less than 900 nm used for the photosensitive layer of the present invention sensitizes a photopolymerization initiator with light in the wavelength region, and various cationic dyes and anionic dyes. As neutral dyes having no charge, merocyanine, coumarin, xanthene, thioxanthene, azo dyes and the like can be used. Among these, particularly preferred examples are dyes selected from cyanine, carbocyanine, hemicyanine, methine, polymethine, triarylmethane, indoline, azine, thiazine, xanthene, oxazine, acridine, rhodamine, and azamethine dyes as cationic dyes. It is. In combination with these cationic dyes, they are preferably used because of their particularly high sensitivity and excellent storage stability. Examples of particularly preferred sensitizing dyes are shown below. The absorption maximum of the sensitizing dye can be obtained by the same method as the absorption maximum of the phthalocyanine compound having an absorption maximum at 900 nm or more.

  There is a preferred range for the proportion of the sensitizing dye having an absorption maximum at 750 nm or more and less than 900 nm in the photosensitive layer. When the entire photosensitive layer is 100 parts by mass, the sensitizing dye is from 0.01 parts by mass. It is preferably contained in the range of 50 parts by mass.

  A known compound can be used as the photopolymerization initiator of the present invention. 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), titanocene compounds, ketoxime compounds, thio compounds, Examples thereof include organic peroxides, onium salts (iodonium salts, diazonium salts, sulfonium salts described in JP-A No. 2003-114532). Among these photopolymerization initiators, organic boron salts and trihaloalkyl-substituted compounds are preferably used in that a particularly sensitive lithographic printing plate can be obtained. More preferably, an organic boron salt and a trihaloalkyl-substituted compound are used in combination. However, because of high sensitivity, image quality problems become prominent when plate making of high-definition AM screens and FM screen images is performed.

  The organic boron anion constituting the organic boron salt is represented by the following general formula (3).

In the formula, each of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ 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 ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ is an alkyl group and the other substituent is an aryl group.

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

  There is a preferred range for the proportion of the organic boron salt in the photosensitive layer, and when the total photosensitive layer is 100 parts by mass, the organic boron salt is included in the range of 0.1 to 50 parts by mass. Preferably it is.

  The above-mentioned trihaloalkyl-substituted compound is specifically a compound having at least one trihaloalkyl group such as a trichloromethyl group or tribromomethyl group in the molecule. As a preferred example, the trihaloalkyl group is a nitrogen-containing compound. Examples of the compound bonded to the heterocyclic 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 heterocyclic ring via a sulfonyl group. It is done.

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

  In the case of using a trihaloalkyl-substituted compound, there is a preferable range in the photosensitive layer, and when the total photosensitive layer is 100 parts by mass, it is contained in the range of 0.1 to 50 parts by mass. Is preferred. Furthermore, these are preferable because the sensitivity is particularly improved when they are contained in the photosensitive layer together with the above-described organic boron salt. In this case, the proportion of the organic boron salt is trihaloalkyl-substituted with respect to 1 part by mass of the organic boron salt. The compound is preferably contained in the range of 0.1 to 50 parts by mass.

  It is one of preferred forms to contain a polymerizable monomer or oligomer in the photosensitive layer of the present invention. Higher sensitivity can be realized by combining a polymerizable monomer or oligomer, and a photosensitive lithographic printing plate excellent in printing performance can be obtained. The molecular weight of the monomer or oligomer is 10,000 or less, preferably 5000 or less. Examples of the compound include compounds having two or more polymerizable double bonds such as acryloyl group, methacryloyl group, and vinylphenyl group.

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

  A compound having a vinylphenyl group as a polymerizable double bond is typically represented by the following general formula (4).

In the formula, Z ₃₁ represents a linking group, and R ₃₁ , R ₃₂ and R ₃₃ 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 ₃₄ represents a substitutable group or atom. m ₃₁ represents an integer of 0 to 4, and k ₃₁ represents an integer of 2 or more.

The general formula (4) will be described in more detail. As the linking group for Z ₃₁ , an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₃₅ ) —, —C (O) —O—, —C (R ₃₆ ) ═N—, Examples include —C (O) —, a sulfonyl group, a heterocyclic group, or a group in which two or more are combined. Here, R ₃₅ and R ₃₆ 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 general formula (4), there are preferable compounds. That is, R ₃₁ and R ₃₂ are hydrogen atoms, R ₃₃ is a hydrogen atom or a lower alkyl group having 4 or less carbon atoms (methyl group, ethyl group, etc.), and k ₃₁ is preferably a compound having 2-10. Although a specific example is shown below, it is not limited to these examples.

  The content of the monomer or oligomer as described above is preferably in the range of 1 to 100% by mass and more preferably in the range of 5 to 50% by mass with respect to the polymerizable polymer.

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

  The urethane compound used in the present invention has at least one urethane bond represented by the following general formula (5) in the molecule. Examples of the polymerizable double bond include an acryloyl group and a methacryloyl group, and it is preferable to have two or more of these polymerizable double bonds. Furthermore, a urethane compound having 2 to 6 urethane bonds and 4 to 10 polymerizable double bonds is preferable.

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

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

  For the support used in the present invention, 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 this case, the aluminum plate that is polished and has an anodized film is an aluminum support that is generally used for lithographic printing plates. In general, an aluminum support used for a lithographic printing plate is a surface roughened in order to improve wettability (water retention) against dampening water during printing and to improve adhesion to the photosensitive layer. Is done. This roughening treatment (so-called graining) is performed by mechanically roughening treatment such as ball graining, wire graining or brush graining, or by chemically dissolving aluminum with chloride, fluoride or the like. A chemical surface roughening treatment, an electrolytic surface roughening treatment performed by electrochemically dissolving aluminum, and a surface roughening method using these methods in combination are known. For example, JP-A-48-28123, JP-A-53-123204, JP-A-54-146234, JP-A-55-25381, JP-A-55-132294, JP-A-56- No. 55291, JP-A-56-150593, JP-A-56-28893, JP-A-58-167196, US Pat. No. 2,344,510, US Pat. No. 3,861, No. 917, US Pat. No. 4,301,229, and the like. Regarding the surface shape of the aluminum plate, U.S. Pat. No. 2,344,510 is a grained structure in which mechanical roughening and electrolytic roughening are performed in a superimposed manner, U.S. Pat. No. 4,301,229. Description is cumulative frequency distribution of pit diameter and centerline average roughness, US Pat. No. 3,861,917 is rough surface depth, Canadian Patent 955449 is rough surface crest height and diameter West German Patent No. 1,813,443 describes the level difference of the rough surface. After such roughening treatment, anodization treatment is performed in an electrolytic solution such as sulfuric acid, phosphoric acid, nitric acid or a mixture thereof.

  As the developer of the present invention, any aqueous alkaline solution can be used as long as the pH is 8 or more. Examples of the alkali agent include sodium hydroxide, potassium hydroxide, ammonium hydroxide, lithium hydroxide, sodium borate, potassium borate, ammonium borate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, Inorganic alkaline agents such as potassium carbonate, ammonium carbonate, dibasic sodium phosphate, dibasic potassium phosphate, dibasic ammonium phosphate, trisodium phosphate, tribasic potassium phosphate and tribasic ammonium phosphate, monomethylamine , Dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine Monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-ethylethanolamine, Nn-butylethanolamine, Nt-butylethanolamine, Nn-butyldiethanolamine, Nt-butyldiethanolamine, Organics such as N-methylethanolamine, N-methyldiethanolamine, N-aminoethylethanolamine, N-aminoethylpropanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide Alkali agents, alkali metal silicates such as sodium silicate, potassium silicate and lithium silicate, ammonium silicate and the like can be mentioned. These can be used alone or in combination of two or more.

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

  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. Moreover, since it is alkaline as a container, it is preferable to use the material which does not permeate | transmit a carbon dioxide gas, and for safety | security does not break during transportation, and usually resin containers, such as a hard bottle and a cube tenor, are used preferably.

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

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

  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.

According to the method described in JP-A-2000-290271 as a synthesis example of a polymerizable polymer, a monomer obtained by reacting equimolar amounts of chloromethylstyrene and bismuthiol and acrylic acid are neutralized with triethylamine and polymerized in ethanol. After the completion of polymerization, the following photosensitive composition was prepared using (P-1) synthesized by reacting chloromethylstyrene, and then graining treatment and anodizing treatment with a wire doctor coater having a thickness of 0.30 mm The sample was coated on the aluminum plate to which the dry film thickness was 3 μm and dried with hot air at 90 ° C. to prepare a sample coated with the photosensitive layer.
Sample contents are listed in Table 1.

<Photosensitive composition>
Polymerizable polymer (P-1) 10 mass% dioxane solution 300 mass parts Photopolymerization initiator (BC-5) 4 mass parts
(T-4) 2 parts by weight Polymerizable monomer (C-5) 15 parts by weight Urethane compound (C-11) 7 parts by weight Sensitizing dye (S-33) 0.2 parts by weight Solvent 1,4-dioxane 70 parts by weight Part
Cyclohexanone 20 parts by mass Addition compounds Table 1 0.1 parts by mass

  The absorption maximum of the additive compound described in Table 1 used in the photosensitive composition was measured with respect to 10 parts by mass of 10% by mass of the polymerizable polymer (P-1) used in the photosensitive composition, and the phthalocyanine compound 0. The absorption of a sample dissolved in 1 part by mass and applied to a 100 μm polyethylene terephthalate film so as to have a dry film thickness of 1 μm was measured, and a comparative sample in which 10% by mass polymerizable polymer (P-1) was applied alone and It calculated | required by the difference of and described in Table 2 below. In addition, it was 830 nm as a result of measuring similarly about the absorption maximum of the sensitizing dye (S-33) used for the photosensitive composition.

Using the 830 nm semiconductor laser mounted plate setter (Dainippon Screen Mfg. Co., Ltd., PlateRite8800Z), the sample produced as described above has a resolution of 4000 dpi / 250 lines, an AM screen, and a laser irradiation energy of 70 mJ / cm ^2. A 50% halftone dot pattern was exposed under the conditions. After the exposure, the following developer was used for development at a liquid temperature of 28 ° C. for 15 seconds, followed by washing with water and drying.

<Developer>
N-ethylethanolamine 30 parts by weight Phosphoric acid (85% by weight solution) 10 parts by weight Potassium hydroxide (48% by weight solution) 13 parts by weight Sodium alkylnaphthalenesulfonate (35% by weight solution) 30 parts by weight Diethylenetriamine 5 acetic acid 1 part by weight Part It adjusted to 1000 mass parts with water.

  With respect to the sample after the development processing, the sharpness and uniformity of the edge portion of the halftone dots were observed, the image quality was evaluated according to the following evaluation criteria, and the results are shown in Table 3 as the image quality evaluation.

○: The image has a sharp edge and a uniform image with no shading.
Δ: Slight disturbance is observed in the edge portion of the image, but a uniform image without shading is formed.
X: Concavities and convexities are seen at the edge of the image, and the image is also shaded, forming a non-uniform image.

  For evaluation of printing durability, a sample prepared by applying a gum solution having the following formulation to the sample after development was used.

<Gum solution>
Phosphoric acid 1 potassium 5 mass parts Gum arabic 25 mass parts Dehydroacetic acid 0.5 mass part EDTA2Na 1 mass part It adjusted to 1000 mass parts with water.

  The printing machine uses Sprint S-226 (trademark of offset printing machine manufactured by Komori Corporation), with a 0.1 mm gauge film sandwiched between the plate cylinder and the plate, and used with a high pressure during printing. The blanket is K400 (manufactured by Kinyo Co., Ltd.), the ink is BEST ONE Ink N (manufactured by T & K TOKA), and the fountain solution is 0.5 of Astro Mark III (manufactured by Nikken Chemical Research Co., Ltd.). A mass% aqueous solution was used, and the following evaluation criteria were used for evaluation based on the number of images where image portions were missing and printing could not be performed. The results are shown in Table 3 as printing durability.

○: More than 200,000 sheets △: More than 150,000 sheets to less than 200,000 sheets ×: Less than 150,000 sheets

The plate making conditions of Example 1 were changed except that a plate setter with a 830 nm semiconductor laser (Trendsetter 800II Quantum manufactured by CREO) was used and the resolution was 2400 dpi, FM screen Staccato 20, and laser irradiation energy 70 mJ / cm ^2. As a result of evaluation in the same manner as in Example 1, the same result as in Example 1 was obtained.

From the above results, the photosensitive lithographic printing plate of the present invention forms a sufficient image with an energy of 70 mJ / cm ² when exposed with a scanning exposure apparatus using a laser emitting light in the near infrared region of 900 nm or less. It can be seen that the photosensitive lithographic printing plate has high sensitivity and excellent image quality, and has excellent printing durability in high-definition AM screen printing and FM screen printing.

Claims (3)

  A photosensitive lithographic printing plate having a photosensitive layer containing a polymerizable polymer, a photopolymerization initiator, and a sensitizing dye having an absorption maximum at 750 nm or more and less than 900 nm capable of sensitizing the photopolymerization initiator on a support. A photosensitive lithographic printing plate comprising a phthalocyanine compound having an absorption maximum at 900 nm or more.   The photosensitive lithographic printing plate according to claim 1, wherein the photopolymerization initiator is an organic boron salt.   3. The photosensitive lithographic printing plate according to claim 1, wherein the polymerizable polymer is a polymer having a phenyl group substituted with a vinyl group in a side chain and a carboxyl group-containing monomer as a copolymerization component. .