JP4620369B2 - Photosensitive composition and photosensitive lithographic printing plate using the same - Google Patents

Description

  The present invention relates to a photosensitive composition, and further to a photosensitive lithographic printing plate using the same. More specifically, the present invention relates to a negative photosensitive composition and a negative photosensitive lithographic printing plate capable of forming an image by ultraviolet irradiation or infrared laser irradiation.

  Conventionally, as a negative photosensitive composition or a negative photosensitive lithographic printing plate, a diazo resin salt and an alkali-soluble resin such as an acrylic resin or a polyurethane resin are used as main photosensitive layer components, and an exposed portion is exposed by ultraviolet exposure. Is photocured and the solubility in a developing solution is reduced, and unexposed areas are developed and dissolved to remove non-images so that the exposed areas are images. Usually, both conventional negative PS plates It is called.

  In addition, a high-sensitivity photosensitive composition that can be directly drawn by a laser and capable of making a plate has also been developed, and is composed of a photopolymerization initiator, a dye sensitizer, and a polymerizable compound. Active compositions have been put to practical use.

  In recent years, high-power semiconductor lasers, YAG lasers, and the like that emit light in the region of 750 nm or more have been used as light sources. For example, Patent Document 1 discloses a resole resin, a novolak resin, a latent bronstec acid, and an infrared ray. A lithographic printing plate comprising an absorbent is disclosed. In this system, the light absorbed by the infrared absorber is converted into heat, and the generated heat decomposes the thermal acid generator to generate an acid. In the subsequent heating step (preheating), the generated acid is converted into a resole resin. It is cured to reduce the solubility in a developing solution to obtain an image. However, the non-image area is easily soiled and poorly developed due to preheating, and inefficiency and uneconomical related to heating are major problems.

  The photopolymerization (photopolymer) -based photosensitive composition sensitive in the above wavelength region is disclosed in Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and the like. Each of the photopolymerization type photosensitive compositions disclosed therein comprises an infrared absorber, a photopolymerization initiator, an ethylenically unsaturated compound, and a binder resin. Polyvinyl alcohol or the like is used on the photosensitive layer. A protective layer (overcoat layer) was provided. Since this overcoat layer is mainly water-soluble, the plates may block each other in a high-humidity atmosphere, and pre-washing for removing the overcoat layer may be necessary during development. When a printing plate is produced, there is an inconvenience in production such that an overcoat layer must be further applied after the photosensitive layer is applied.

  Photopolymerizable photosensitive compositions that do not require such an overcoat layer are disclosed in Patent Documents 6 and 7. However, these have a tendency to weaken the photosensitive layer in order to achieve high sensitivity. For this reason, the surface of the photosensitive layer is scratched or long-term in a high-temperature, high-humidity atmosphere during handling or development processing. Below, there are problems such as causing a decrease in sensitivity.

Further, as a diazo photosensitive composition sensitive in the near infrared wavelength region, Patent Document 8 discloses a negative containing a substance that absorbs light and generates heat and a diazonium compound having two or more diazonio groups in the molecule. Type image recording materials have been disclosed, but this alone has problems such as poor sensitivity and adhesion to a support and difficulty in forming an image.
Japanese Unexamined Patent Publication No. 7-20629 JP 2000-122273 A Japanese Unexamined Patent Publication No. 2000-122274 Japanese Unexamined Patent Publication No. 2000-131833 JP 2000-131837 A Japanese Patent Laid-Open No. 2002-244288 Japanese Patent Laid-Open No. 2003-315990 Japanese Unexamined Patent Publication No. 7-306528

  Accordingly, an object of the present invention relates to a negative photosensitive composition that can be developed with an aqueous alkaline solution after irradiation with ultraviolet light or irradiation with a solid laser or semiconductor laser having an oscillation wavelength in the near infrared to infrared region, The present invention provides a photosensitive composition and a photosensitive lithographic printing plate having high sensitivity, excellent adhesion to a support and scratch resistance, high printing durability, and no need for an overcoat layer.

That is, according to the present invention, (A) an alkali-soluble resin, (B) a diazo resin salt, (C) a polymerizable compound having two or more ethylenic double bonds, (D) an infrared absorber, and (E) A photosensitive composition for near-infrared or infrared irradiation containing an organic boron salt, wherein the photosensitive composition further contains an imidazole compound, and the alkali is added to the total solid content of the photosensitive composition. The soluble resin content is 10 to 95% by weight, the diazo resin salt content is 1 to 50% by weight, and the ethylenically unsaturated compound content is 1 to 60% by weight. The content of the infrared absorber is 0.5 to 20.0% by weight, the content of the organic boron salt is 0.5 to 30.0% by weight, and the content of the imidazole compound is , which is 0.5 to 10.0% by weight Light composition, as well as on a support, a photosensitive lithographic printing plate having a photosensitive composition is provided.

  As will be described in detail below, the photosensitive lithographic printing plate provided with the photosensitive composition according to the present invention does not require an overcoat layer, and is the same as a conventional PS plate after UV exposure or laser exposure. A printing plate that can be developed with an alkali developer, has high sensitivity, is excellent in adhesion to a support and scratch resistance, and has high printing durability can be obtained.

  Hereinafter, embodiments of the present invention will be described. However, the embodiments described below do not limit the present invention. According to the present invention, near infrared or infrared light irradiated by an infrared laser or the like is absorbed by the infrared absorbent and converted into heat. The diazo resin salt is thermally decomposed by the generated heat, thereby reducing the solubility of the diazo resin salt in the developer. At the same time, when light in this wavelength range is irradiated, the organoboron salt serves as a radical generator and polymerizes the polymerizable compound. In particular, when a resin having a double bond group is present, the organoboron salt is made to be a higher polymer by entwining a polymerizable compound with the group. Thereby, it is considered that the film strength is improved, the sensitivity is high, the adhesiveness with the support is excellent, and the printing durability is improved. Accordingly, if either the diazo resin salt or the organic boron salt is removed, the adhesion to the support is deteriorated, the image portion is easily scratched, and the image is easily lost or peeled off. In addition, when irradiated with ultraviolet rays, the diazo resin salt is photodegraded with ultraviolet light (about 300 to 500 nm) and has a property of reducing solubility in a developing solution. It can also be used as a sex composition.

  In the present invention, it is desirable that the alkali-soluble resin used as the component (A) is soluble and swellable in an alkaline aqueous solution as a developer. Examples of such alkali-soluble resins include the following acrylic copolymers and polyurethane resins.

Although not particularly limited, the acrylic copolymer used in the present invention is a monomer selected from the following (1) to (10), a conventionally known graft copolymerization method, block copolymerization method, It can be obtained by copolymerization using a random copolymerization method or the like.
(1) A monomer having a phenolic hydroxyl group. For example, N- (4-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) methacrylamide, N- (4-hydroxyphenyl) methylacrylamide, N- (3,5-dimethyl-4-hydroxyphenyl) methylacrylamide P-isopropenyl phenol, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p-hydroxyphenyl methacrylate.
(2) A monomer having a sulfonamide group. For example, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) acrylamide.
(3) A monomer having an active imide group. For example, N- (p-toluenesulfonyl) methacrylamide and N- (p-toluenesulfonyl) acrylamide.
(4) A monomer having an aliphatic hydroxyl group. For example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-phenoxypropyl methacrylate.
(5) α, β-unsaturated carboxylic acid. For example, acrylic acid, methacrylic acid, and maleic anhydride.
(6) A monomer having an allyl group. For example, allyl methacrylate and N-allyl methacrylamide.
(7) Alkyl acrylates or alkyl methacrylates. For example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, They are butyl methacrylate, amyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, and glycidyl methacrylate.
(8) Acrylamides or methacrylamides. For example, acrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl acrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, methacrylamide, N-methylol methacrylamide, N-ethyl Methacrylamide, N-hexylmethacrylamide, N-cyclohexylmethacrylamide, N-hydroxyethylmethacrylamide, N-phenylmethacrylamide.
(9) Styrenes. For example, styrene, α-methylstyrene, chloromethylstyrene and the like.
(10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.

  The polystyrene calculated weight average molecular weight (hereinafter abbreviated as Mw) by gel permeation chromatography (GPC) measurement of the acrylic copolymer is preferably 1,000 to 500,000, particularly preferably 1,500 to 300,000. Is used. If Mw is smaller than the above range, a sufficient coating film cannot be obtained. If Mw is larger than this range, the solubility of the unexposed portion in the alkaline developer is deteriorated and development is impossible.

  Although it is not particularly limited, as the polyurethane resin used in the present invention, the glass transition temperature (Tg) of the polymer is in the range of 50 ° C to 180 ° C, more preferably in the range of 80 ° C to 150 ° C. And solvent-soluble alkali-soluble polyurethane resins are useful. When the glass transition temperature (Tg) is 50 ° C. or less, film formability, that is, a uniform surface of the photosensitive layer may be difficult to form, and surface stickiness may easily occur. Absent. In addition, when Tg is 180 ° C. or higher, alkali solubility is deteriorated and development failure may occur easily, which is not preferable. Here, in this specification, the glass transition temperature (Tg) was measured using a differential scanning calorimeter DSC-60 (manufactured by Shimadzu Corporation). The average molecular weight (Mw) of the polyurethane resin is not particularly limited, and any conventionally used polyurethane resin can be used.

  Generally, the alkali-soluble polyurethane resin is a polyurethane resin containing a group having a carboxyl group in the main chain or side chain, and preferably a reaction product of a diisocyanate compound and a diol compound containing a carboxyl group as a basic skeleton. Polyurethane resin to be included.

  Further, the alkali-soluble polyurethane resin is a polyurethane resin having a side chain carboxyl group as described in JP-A No. 2002-311579, and an addition reaction of glycidyl methacrylate with the carboxyl group results in polymerization at the terminal. An alkali-soluble polyurethane resin having a double bond group is particularly preferred.

  Specific examples of the diisocyanate compound preferably used for synthesizing the polyurethane resin used in the present invention include those shown below. That is, as the diisocyanate compound, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 3,3 '-Dimethylbiphenyl-4,4'-diisocyanate, hexanemethylene diisocyanate, trimethylhexanemethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexyl 2,4- ( Alternatively, 2,6) diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane and the like can be mentioned.

  Specific examples of the diol compound having a carboxyl group used in the present invention include the following. That is, as a diol compound having a carboxyl group, 3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxyethyl) propionic acid, 2,2-bis (hydroxypropyl) ) Propionic acid, N, N-2,2-dihydroxyethylglycine, bis (hydroxymethyl) acetic acid, 4,4-bis (4-hydroxyphenyl) pentanoic acid, tartaric acid and the like.

  The content rate in the polyurethane resin of the said diol compound which has a carboxyl group is 20-50 mol%, More preferably, it is 25-45 mol%. If it is less than 20 mol%, the developability may be deteriorated, and the addition ratio of glycidyl methacrylate is also narrowed. If it exceeds 50 mol%, the image strength during development is deteriorated and other diol components cannot be contained at the same time. There is a case.

  Moreover, the diol compound which does not have a carboxyl group and may have the other substituent which does not react with isocyanate can also be used, Specifically, what is shown below is included. That is, as a diol compound, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polyester polyol, polycarbonate diol, neopentyl glycol, 1,3-butylene glycol, 1 , 6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-bis-β-hydroxyethoxycyclohexane, cyclohexanedimethanol, tricyclodecane dimethanol, hydrogenated bisphenol A, water Bisphenol F, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, ethylene of bisphenol F Xide adduct, propylene oxide adduct of bisphenol F, ethylene oxide adduct of hydrogenated bisphenol A, propylene oxide adduct of hydrogenated bisphenol A, hydroquinone dihydroxyethyl ether, p-xylene glycol, dihydroxyethyl sulfone, bis- (2 -Hydroxyethyl) -2,4-tolylene dicarbamate, 2,4-tolylene-bis- (2-hydroxyethyl) -m-xylene carbamate, bis (2-hydroxyethyl) isophthalate and the like.

  A polyurethane resin having a side chain carboxyl group, wherein an alkali-soluble polyurethane resin having a polymerizable double bond group at the end by addition reaction of glycidyl methacrylate with the carboxyl group is synthesized in a two-step reaction. Can do. First, the synthesis of polyurethane as a basic skeleton is a known process having an activity corresponding to the reactivity of the diisocyanate compound, the diol compound having a carboxyl group and the diol compound having no carboxyl group in an aprotic solvent. It can be synthesized by adding a catalyst and heating. Next, the alkali-soluble polyurethane resin can be synthesized by addition reaction of glycidyl methacrylate with the obtained polyurethane as the basic skeleton. The molar ratio of the diisocyanate compound and diol compound to be used is preferably 0.8: 1 to 1.2: 1. When an isocyanate group remains at the end of the polymer, it is treated with alcohols or amines. Thus, the compound is finally synthesized in such a manner that no isocyanate group remains.

  The introduction rate of glycidyl methacrylate is 20 to 70%, more preferably 30 to 60%, based on the carboxyl group in the polyurethane that is the basic skeleton in the first stage. When the introduction rate is less than 20%, the effect of high printing durability may be difficult, and when the introduction rate is 70% or more, developability may be deteriorated.

  As other alkali-soluble polyurethane resins, those described in JP-A-7-64286 and JP-A-2000-275832 can be used.

  In addition to the above acrylic copolymer and polyurethane resin, the photosensitive composition of the present invention includes polyamide, polyether, polyester, polycarbonate, polystyrene, polyvinyl butyral resin, epoxy resin, phenol resin, cresol resin, polyvinyl phenol resin. Etc. can also be added.

  The alkali-soluble resins used in the present invention may be used alone or in combination of two or more. The addition amount is 10 to 95% by weight, preferably 20 to 90% by weight, based on the photosensitive layer made of the photosensitive composition of the present invention (that is, based on the total solid content of the photosensitive composition). When the addition amount is 10% by weight or more, the printing durability is improved, and when it is 95% by weight or less, the sensitivity is improved, which is preferable.

  As described above, the photosensitive composition according to the present invention contains (B) a diazo resin salt. As described above, the diazo resin salt is thermally decomposed by the heat generated by the infrared absorber, and the solubility in the developer is reduced. Therefore, by containing the diazo resin salt, the adhesion to the support is improved, the image portion is hardly scratched, and image loss and peeling are less likely to occur.

  In the present invention, the diazo resin salt used as the component (B) contains a diazo monomer having a 4-diazodiphenylamine skeleton, a 4-diazodiphenyl ether skeleton or a 4-diazodiphenyl sulfide skeleton and an aldehyde or carboxyl group. A diazo resin known in the form of a condensate with aldehydes or a cocondensate of an aromatic compound condensable with the aldehydes in the form of an organic salt or an inorganic salt can be used.

  Specific examples of the diazo monomer include 4-diazodiphenylamine, 4′-hydroxy-4-diazodiphenylamine, 4′-methoxy-4-diazodiphenylamine, 4′-ethoxy-4-diazodiphenylamine, 4′-methyl. -4-diazodiphenylamine, 4'-ethyl-4-diazodiphenylamine, 4-diazo-3-methoxydiazodiphenylamine, 3-methyl-4-diazodiphenylamine, 3-ethyl-4-diazodiphenylamine, 3'-methyl-4 -Diazodiphenylamine, 3-ethoxy-4-diazodiphenylamine, 4-diazodiphenyl ether, 4'-methoxy-4-diazodiphenyl ether, 4'-carboxy-4-diazodiphenyl ether, 4-diazo Diphenyl sulfide, 4'-methyl-4-diazodiphe Rusurufido and the like.

  Specific examples of the aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glyoxylic acid and the like. Moreover, it can also condense using 4,4'- dimethoxymethyl diphenyl ether instead of the said aldehydes.

  Specific examples of aromatic compounds that can be condensed with the aldehydes include benzoic acid, salicylic acid, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, p-methoxybenzoic acid, cinnamic acid, and p-hydroxycinnamic acid. Examples include acid, methyl cinnamate, p-methoxycinnamic acid, cinnamylidene acetic acid, p-hydroxycinnamylidene acetic acid, and the like.

  The diazo monomer, aldehydes, and aromatic compounds can be synthesized by known methods, and commercially available products can be used. The diazo resin can be synthesized by condensing these by a known method, or a commercially available product can be used. The weight average molecular weight (Mw) of the diazo resin is not particularly limited, and any conventionally used diazo resin can be used.

  Examples of organic compounds that react with the diazo resin to form organic salts include the compounds described in JP-B-40-2203, JP-B-41-6813, JP-B-47-1167, and the like, specifically Benzenesulfonic acid, p-toluenesulfonic acid, 2,5-xylenesulfonic acid, long chain or branched dodecylbenzenesulfonic acid, 2-methoxy-4-hydroxy-5-benzoylbenzenesulfonic acid, and alkali metal salts thereof, Examples include alkaline earth metal salts and ammonium salts. Examples of inorganic compounds that react with the diazo resin to form inorganic salts include compounds described in JP-B-40-2203, JP-A-54-98613, US Pat. No. 4093465, and the like. Includes borohydrofluoric acid, hexafluorophosphoric acid, phosphotungstic acid, thiocyanic acid, and alkali metal salts and ammonium salts thereof.

  When the photosensitive composition of the present invention is used as a photosensitive layer, the content of the diazo resin salt of the component (B) in the photosensitive layer is based on the total solid content of the photosensitive layer (that is, the total solid content of the photosensitive composition). Usually 1 to 50% by weight, preferably 2 to 40% by weight. If it is less than 1% by weight, the photocuring power may be poor and an image may be hardly formed. On the other hand, if it exceeds 50% by weight, the sensitivity may be slow or the printing durability may be deteriorated.

  As described above, the photosensitive composition according to the present invention contains (C) a polymerizable compound having two or more ethylenic double bonds. As described above, when irradiated with near-infrared rays or infrared rays, the organic boron salt serves as a radical generator and polymerizes the polymerizable compound. In particular, when a resin having a double bond group is present, the organoboron salt has a higher molecular weight by entangled a polymerizable compound with the group. Thereby, it is considered that the film strength is improved, the sensitivity is high, the adhesiveness with the support is excellent, and the printing durability is improved.

  As the polymerizable compound having two or more ethylenic double bonds, various compounds from monomers having a molecular weight of 1000 or less to oligomers having a molecular weight of 1000 or more and those having a polymer region can be used. Such compounds include esters of unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.) and aliphatic polyhydric alcohol compounds, unsaturated carboxylic acids and aliphatic Examples include amides with polyvalent amine compounds, urethanes with unsaturated alcohols and isocyanate compounds, and esters with unsaturated carboxylic acids and epoxy compounds.

  More specifically, in the present invention, as the polymerizable compound having two or more ethylenic double bonds used as the component (C), for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol diacrylate can be used. Methacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, butylene glycol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, neopentyldiol diacrylate, neopentyldiol dimethacrylate , Polypropylene glycol diacrylate, methoxydiethylene glycol Tacrylate, methoxytetraethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, trimethylolpropane trimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, di Examples include pentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

  The polymerizable compound having two or more ethylenic double bonds can be synthesized by a known method, or a commercially available compound can be used. Moreover, the weight average molecular weight (Mw) of the polymerizable compound having two or more ethylenic double bonds is not particularly limited, and any conventionally used diazo resin can be used.

  The amount of the ethylenically unsaturated compound added is preferably 1 to 60% by weight, more preferably 2 to 50%, based on the total solid content of the photosensitive layer (that is, based on the total solid content of the photosensitive composition). % By weight. When the addition amount is 1.0% by weight or more, the sensitivity becomes faster, and when it is 60% by weight or less, scratch resistance of the image portion (exposed portion) is further improved, which is preferable.

  As described above, the photosensitive composition according to the present invention contains (D) an infrared absorber. The infrared absorber is used for the purpose of thermally decomposing the diazo portion of the diazo resin by the generated heat and for the purpose of a sensitizer for the radical generator. That is, as described above, near infrared or infrared light irradiated by an infrared laser or the like is absorbed by the infrared absorbent and converted into heat. The diazo resin salt is thermally decomposed by the generated heat, and the solubility in the developer is reduced. On the other hand, when irradiated with near-infrared or infrared rays, the organic boron salt serves as a radical generator and polymerizes the polymerizable compound. The generation of radicals is promoted.

The infrared absorber used as the component (D) of the present invention is a photothermal conversion that generates heat by irradiation with near infrared or infrared rays (preferably light having a wavelength of 700 nm to 2500 nm, more preferably 700 nm to 1300 nm). A substance having a function is preferred. As the infrared absorbent used in the present invention, an infrared absorbing dye having absorption at a wavelength of 700 nm or more, carbon black, magnetic powder, and the like can be used. A particularly preferable infrared absorber is an infrared absorbing dye having an absorption peak at a wavelength of 700 nm to 850 nm and having a peak molar absorption coefficient ε of 10 ⁵ or more.

  As the infrared absorbing dyes, cyanine dyes, squalium dyes, croconium dyes, azurenium dyes, phthalocyanine dyes, naphthalocyanine dyes, polymethine dyes, naphthoquinone dyes, thiopyrylium dyes, dithiol metal complex dyes, Anthraquinone dyes, indoaniline metal complex dyes, intermolecular CT dyes and the like are preferable.

These dyes can be synthesized by a known method. Moreover, the following commercial items can also be used.
Nippon Kayaku Co., Ltd .: IR750 (anthraquinone), IR002, IR003 (aluminum), IR820 (polymethine), IRG022, IRG033 (diimmonium), CY-2, CY-4, CY-9, CY-10, CY-20
Dai Nippon Ink Chemical Co., Ltd .: Fastogen blue 8120
Midori Chemical Co., Ltd .: MIR-101, 1011 and 1021
In addition, the above dyes are commercially available from companies such as Nippon Photosensitive Dye Co., Ltd. and Sumitomo Chemical Co., Ltd.

  In the present invention, the amount of the infrared absorber added is preferably 0.5 to 20.0% by weight, more preferably based on the total solid content of the photosensitive layer (that is, based on the total solid content of the photosensitive composition). Is 1.0 to 15.0% by weight. When the addition amount is 0.5% by weight or more, the sensitivity is faster, and when it is 20.0% by weight or less, the developability of the non-image part (exposed part) is further improved.

  As described above, the photosensitive composition according to the present invention contains (E) an organic boron salt. As described above, when irradiated with near-infrared rays or infrared rays, the organic boron salt serves as a radical generator and polymerizes the polymerizable compound. In particular, when a resin having a double bond group is present, the organoboron salt has a higher molecular weight by entangled a polymerizable compound with the group. Thereby, it is considered that the film strength is improved, the sensitivity is high, the adhesiveness with the support is excellent, and the printing durability is improved.

  In the present invention, the organic boron salt used as the component (E) is used as a radical generator for radical polymerization of an ethylenically unsaturated compound, and an organic boron anion-counter cation complex is preferably used. Examples of the organic boron anion include those described in JP-A-62-143044, JP-A-9-88685, JP-A-9-188686, JP-A-9-188710, and the like. Methyl-diphenylboron anion, n-butyl-triphenylboron anion, n-butyl-trinaphthylboron anion, n-butyl-tri (p-methoxyphenyl) boron anion, n-butyl-tri (t-butylphenyl) boron Anions and the like are preferable.

  Examples of the counter cation include ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, and phosphonium salts such as triarylalkylphosphonium salts.

  In the present invention, the amount of the organic boron salt added is preferably 0.5 to 30.0% by weight, more preferably based on the total solid content of the photosensitive layer (that is, based on the total solid content of the photosensitive composition). Is 1.0 to 25.0% by weight. When the addition amount is 0.5% by weight or more, the sensitivity becomes faster, and when it is 30.0% by weight or less, the developability of the non-image part (exposed part) is further improved, which is preferable. In addition, the said organic boron salt can be synthesize | combined by a well-known method, and a commercially available thing can be used.

  It is preferable that the photosensitive composition of the present invention further contains an imidazole compound. The imidazole compound is used as a radical generator and is used to increase sensitivity. Specific examples of the imidazole compound include hexaarylbisimidazole, 2- (2-chlorophenyl) -4,5-diphenylimidazole dimer, and 2- (2,3-dichlorophenyl) -4,5-diphenylimidazole dimer. And 2- (2-chlorophenyl) -4,5-bis (4-methoxyphenyl) imidazole dimer.

  The amount of the imidazole compound added is preferably 0.5 to 10.0% by weight, more preferably 0.6%, based on the total solid content of the photosensitive layer (that is, based on the total solid content of the photosensitive composition). -8.0 wt%. When the addition amount is 0.5% by weight or more, the sensitivity is faster, and when it is 10.0% by weight or less, the developability of the non-image area (exposed area) is further improved, which is preferable. In addition, the said imidazole compound can be synthesize | combined by a well-known method, and a commercially available thing can be used.

  In addition to the above-described components, various additives can be added to the photosensitive composition of the present invention as necessary as long as the effects of the present invention are not impaired. For example, a dye or a pigment can be added for the purpose of coloring the photosensitive composition of the present invention. As the dye, an oil-soluble dye and a basic dye are preferable. Specifically, Crystal Violet, Malachite Green, Victoria Bull, Methylene Blue, Ethyl Violet, Rhodamine B, Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd.), Oil Blue 613 (Orient Chemical Co., Ltd.) ), Oil green and the like are preferable.

  As the pigment, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone red, indanthrene blue and the like are preferable.

  The amount of these dyes or pigments added is 0.05 to 10.0% by weight, more preferably 0.1 to 8.0% by weight, based on the total solid content of the photosensitive layer. If it is 0.05% by weight or more, the image forming layer is sufficiently colored and the image can be easily seen, and if it is 10.0% by weight or less, a dye residue hardly remains in the non-image area after development.

  In addition, phosphoric acid, phosphorous acid, oxalic acid, citric acid, malic acid, tartaric acid, mandelic acid, 2-methoxy-5-benzoyl-benzenesulfonic acid, benzophenone derivatives, etc. are added as storage stabilizers for diazo resin salts. be able to.

  The photosensitive composition of the present invention has a nonionic surfactant as described in JP-A-62-251740 and JP-A-3-208514, in order to broaden the processing stability against development conditions. Amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149 can be added. Preferable examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether (for example, trade name “ Emulgen 404 "manufactured by Kao Corporation). Preferred examples of the amphoteric surfactant include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, and N-tetradecyl-N, N- Examples include betaine type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Co., Ltd.). The proportion of the nonionic surfactant and the amphoteric surfactant in the photosensitive layer is preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight.

  A plasticizer can be added to the photosensitive layer of the present invention in order to impart flexibility and the like of the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, trioctyl phosphate, tributyl phosphate and the like are used.

  Although not particularly limited, a photosensitive layer is provided by applying a photosensitive solution obtained by dissolving the above components in a solvent onto a support, whereby a photosensitive lithographic printing plate can be produced. .

  Examples of the solvent include methanol, ethanol, propanol, methylene chloride, ethyl acetate, tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, dimethylformamide, dimethyl Examples thereof include, but are not limited to, sulfoxide, dioxane, dioxolane, acetone, cyclohexanone, trichloroethylene, and methyl ethyl ketone. These solvents can be used alone or in admixture of two or more. The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by weight.

Various methods can be used as the coating method, and examples thereof include spin coating, extrusion coating, bar coater coating, roll coating, air knife coating, dip coating, and curtain coating. The coating amount of the photosensitive layer varies depending on the use, but is preferably 0.5 to 5.0 g / m ² at the time of drying.

  Examples of the support include a metal plate such as aluminum, zinc, copper, or steel, a metal plate plated or vapor-deposited with chromium, zinc, copper, nickel, aluminum, iron, or the like, paper, plastic film, or glass. Examples thereof include a plate, paper coated with a resin, and a plastic film subjected to a hydrophilic treatment.

  As the support of the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a small amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Thus, the composition of the aluminum plate applied to the present invention is not specified, and conventionally known and used aluminum plates can be appropriately used. The thickness of the aluminum plate used in the present invention is approximately 0.1 to 0.5 mm, preferably 0.15 to 0.3 mm.

  Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant or an alkaline aqueous solution is performed to remove the rolling oil on the surface. The surface roughening treatment of the surface of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically roughening the surface, and a method of selectively dissolving the surface chemically. By the method. As the mechanical method, known methods such as brush polishing, ball polishing, blast polishing, and buff polishing can be used. In addition, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, a method combining a mechanical method and an electrochemical method disclosed in JP-A-53-123204 can also be used. The roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization treatment to enhance the surface water retention and wear resistance as desired. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid or a mixed acid thereof is used as an electrolyte used for anodizing the aluminum plate.

The treatment conditions for anodization vary depending on the electrolyte used and cannot be specified. However, in general, the concentration of the electrolyte is 1 to 60% by weight, the liquid temperature is 5 to 60 ° C., and the current density is 2 to 50 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 5 seconds to 3 minutes are suitable. If the amount of anodic oxide film is 0.5 to 4.0 g / m ² is appropriate, small and wear resistance becomes worse than 0.5 g / m ^2, When it is 4.0 g / m ² or more, the anodic oxidation It is not preferable because a dye or the like easily penetrates into the holes.

  After the anodization, the aluminum plate is further subjected to a chemical conversion treatment with, for example, an alkali silicate, sodium phosphate, sodium fluoride, zirconium fluoride, alkyl titanate, trihydroxybenzoic acid alone or in a mixed solution, Sealing treatment by immersion in aqueous solution or steam bath, coating treatment with aqueous solution such as strontium acetate, zinc acetate, magnesium acetate or calcium benzoate, polyvinylpyrrolidone, polyaminesulfonic acid, polyvinylphosphonic acid, polyacrylic acid Alternatively, a surface or back surface coating treatment with polymethacrylic acid or the like can be performed as a post-treatment.

  Furthermore, as the above-mentioned support, an aluminum support subjected to the surface treatment described in JP-A-10-297130 can be used.

  A matte layer can also be provided on the surface of the photosensitive lithographic printing plate coated with the photosensitive composition as described above. This is to improve the detachability between the plates when a large number of photosensitive lithographic printing plates are stacked without interleaving paper, and to improve the detachability between the interleaving paper and the plate when interposing and interposing the interleaving paper. .

  Further, a matting agent may be contained in the photosensitive layer for the purpose of improving the detachability between the plates as described above and the detachability between the plates and the interleaf.

  As a laser light source for irradiating the photosensitive lithographic printing plate of the present invention, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser or a semiconductor laser is preferable. The emission wavelength is preferably 760 to 850 nm. Examples of the light source for ultraviolet exposure include a carbon arc lamp, a mercury lamp, a metal halide lamp, a xenon lamp, and a chemical lamp. The emission wavelength is preferably 300 to 500 nm.

  As the developer and developer replenisher used for developing the photosensitive lithographic printing plate of the present invention, a water-based alkaline developer is suitable. Examples of the aqueous alkali developer include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium metasilicate, potassium metasilicate, dibasic sodium phosphate, tribasic sodium phosphate and the like, octanoic acid Aqueous solutions such as sodium, alkylamines and tetramethylammonium hydroxide can be used. These alkali agents are used alone or in combination of two or more.

  A surfactant and / or a solvent can be added to the developer and the development replenisher as necessary. As the surfactant, an anionic surfactant or an amphoteric surfactant can be used.

  Examples of the anionic surfactant include sulfates of alcohols having 8 to 22 carbon atoms (for example, polyoxyethylene alkyl sulfate soda salt), alkylaryl sulfonates (for example, sodium dodecylbenzenesulfonate, polyoxyethylene dodecylphenyl). For example, sulfate soda salt, alkyl naphthalene sulfonate soda, naphthalene sulfonate soda, formalin condensate of naphthalene sulfonate soda, sodium dialkyl sulfonate, alkyl ether phosphate, alkyl phosphate, and the like can be used. In addition, as the amphoteric surfactant, for example, alkylbetaine type and alkylimidazoline type surfactants are preferable.

  As the solvent, alcohols and ethers are preferable, but solvents that do not dissolve 10% or more in water (20 ° C.) are preferable. Examples of this type of solvent include benzyl alcohol and phenyl glycol. . Furthermore, water-soluble sulfites such as sodium sulfite, potassium sulfite, lithium sulfite, and magnesium sulfite can be added.

  The synthesis examples and examples of the present invention will be described in more detail below, but the present invention is not limited thereto.

[Synthesis Example 1: Synthesis of alkali-soluble polyurethane resin]
In a 500 ml three-necked round bottom flask equipped with a condenser, a thermometer and a stirrer, 26.8 g (0.2 mol) of 2,2-bis (hydroxymethyl) propionic acid (OH equivalent 67), polyester polyol A (OH Equivalent 545) 27.3 g (0.025 mol) and polypropylene glycol (OH equivalent 198) 9.9 g (0.025 mol) were added and dissolved in 150 g of N, N-dimethylacetamide. To this was added 62.5 g (0.25 mol) of 4,4-diphenylmethane diisocyanate (NCO equivalent 125), and the mixture was heated and stirred at 80 ° C. for 4 hours. Furthermore, 14.2 g (0.1 mol) of glycidyl methacrylate (molecular weight 142.2) and 0.1 g of triethylbenzylammonium chloride were added, and the mixture was heated and stirred at 100 ° C. for 4 hours. Thereafter, 160 g of methanol was added for dilution. The reaction solution was poured into 5 liters of water while stirring to precipitate a white target resin. This resin was separated by filtration, washed with water and dried to obtain 120 g of resin. The acid value of this resin was 40 mgKOH / g, the rate of introduction into carboxyl groups was 50%, and the weight average molecular weight was 61,000.

  The polyester polyol A used in the above synthesis was prepared as follows. That is, a column (25 to 30 cm) with a glass helix attached to a 500 ml round bottom flask was connected to a fractionator for moisture measurement filled with hexane. In a reaction vessel, 146.1 g (1.00 mol) of adipic acid, 41.0 g (0.66 mol) of ethylene glycol and 39.7 g (0.44 mol) of 1,4-butanediol were gradually heated to 200 ° C., The reaction was allowed for 8 hours. After completion of the reaction, heating was stopped, the moisture measuring fraction receiver was removed and replaced with a distillation connecting tube, and unreacted starting materials and by-products were distilled off at 200 ° C. (7.5 mmHg) over 15 hours. The yield of the obtained polyester polyol A was 171.0 g, the OH equivalent was 545, and the water content was 0.02% by weight.

[Synthesis Example 2: Synthesis of alkali-soluble acrylic copolymer]
As a reaction solvent, 200 g of methyl cellosolve and a mixture having the following composition were added to a 1 L four-necked flask equipped with a stirrer and a condenser. After heating the inside of the flask to 100 ° C., 0.4 g of azobisisobutyronitrile was added, and after replacing with nitrogen gas, the mixture was stirred at 100 ° C. for 5 hours. After completion of the reaction, the reaction mixture was poured into 10 L of water, filtered and dried. The yield was about 97 g and the weight average molecular weight was about 52,000.

〔composition〕
4-tert-butylcyclohexyl acrylate (15 g)
・ 2-Hydroxyethyl methacrylate (50 g)
・ Methacrylic acid (5g)
・ Methyl methacrylate (10g)
・ Acrylonitrile (20g)

[Production of support]
An aluminum plate (material 1050) having a thickness of 0.24 mm was degreased with alkali, then the surface was polished with a nylon brush while applying a water suspension of permiston, and then thoroughly washed with water. Next, a 15% by weight sodium hydroxide aqueous solution was poured for 5 seconds at 70 ° C., the surface was etched by 3 g / m ² , then further washed with water, and then an electrolytic solution composed of 1N hydrochloric acid and aluminum ions (20 g / L). Electrolytic polishing was performed at 200 coulomb / dm ² . Subsequently, after washing with water, the surface was etched again with a 15% by weight sodium hydroxide aqueous solution at 70 ° C., washed with water, and then anodized in a 15% sulfuric acid aqueous solution at 30 ° C. to obtain 2.0 g / m 2. ^Two anodized films were formed. After washing with water, it was immersed in a JIS 3 sodium silicate 5% by weight aqueous solution at 70 ° C. for 10 seconds, washed with water and dried.

[Examples 1 to 3]
Next, using the photosensitive solutions [A-1], [A-2], and [A-3] having the following compositions, they are applied on the aluminum plate and dried, and then Examples 1 to 3 are applied. Photosensitive planographic printing plates [A-1], [A-2], and [A-3] were prepared. The coating amount at this time was 1.8 g / m ² in terms of dry weight.

[Photosensitive solution [A-1]]
Alkali-soluble resin (Synthesis example 1) (2.00 g)
・ Dodecylbenzenesulfonate salt of condensate of 4-diazodiphenylamine and formaldehyde (0.30 g)
・ Dipentaerythritol hexaacrylate (2.00 g)
-Cyanine compound (A) shown below (0.2 g)
N-Butyl-triphenylboron-tetrabutylammonium complex (0.6 g)
・ Victoria Pure Blue BOH (0.08g)
・ Propylene glycol monomethyl ether (80g)
・ Ethylene glycol monomethyl ether (20g)

[Photosensitive solution [A-2]]
Alkali-soluble resin (Synthesis example 1) (2.00 g)
・ Dodecylbenzenesulfonate salt of condensate of 4-diazodiphenylamine and formaldehyde (0.30 g)
・ Pentaerythritol tetraacrylate (2.00 g)
-Cyanine compound (A) shown above (0.2 g)
N-Butyl-tri (t-butylphenyl) boron-tetrabutylammonium complex (0.5 g)
2- (2-chlorophenyl) -4,5-diphenylimidazole dimer (0.1 g)
・ Victoria Pure Blue BOH (0.08g)
・ Propylene glycol monomethyl ether (80g)
・ Ethylene glycol monomethyl ether (20g)

[Photosensitive solution [A-3]]
Alkali-soluble resin (Synthesis example 2) (2.00 g)
-2-Methoxy-4-hydroxy-5-benzoylbenzenesulfonate salt of condensate of 4-diazodiphenylamine and formaldehyde (0.30 g)
・ Dipentaerythritol hexaacrylate (2.00 g)
-Cyanine compound (A) shown above (0.2 g)
N-Butyl-triphenylboron-tetrabutylammonium complex (0.6 g)
・ Victoria Pure Blue BOH (0.08g)
・ Propylene glycol monomethyl ether (80g)
・ Ethylene glycol monomethyl ether (20g)

[Comparative Example 1]
Next, as Comparative Example 1, a photosensitive solution [B-1] obtained by removing the organic boron salt (n-butyl-triphenylboron-tetrabutylammonium complex) from the above photosensitive solution [A-1] was prepared, and the photosensitive solution [A-1] A-1] was applied in the same manner to prepare a photosensitive lithographic printing plate [B-1].

[Comparative Example 2]
As Comparative Example 2, a photosensitive solution [B-2] obtained by removing diazo resin salt (dodecylbenzenesulfonate salt of condensate of 4-diazodiphenylamine and formaldehyde) from the above photosensitive solution [A-1] was prepared. [A-1] The same application was performed to prepare a photosensitive lithographic printing plate [B-2].

[Comparative Example 3]
As Comparative Example 3, a photosensitive solution [B-3] obtained by removing the organic boron salt (n-butyl-tri (t-butylphenyl) boron-tetrabutylammonium complex) from the above photosensitive solution [A-2] was prepared. Coating was performed in the same manner as the photosensitive solution [A-2] to prepare a photosensitive lithographic printing plate [B-3].

  The performance evaluation of each lithographic printing plate of Examples 1 to 3 and Comparative Examples 1 to 3 produced as described above was performed as follows.

[Evaluation of sensitivity]
Each of the above printing plates was exposed using a semiconductor laser having a wavelength of 830 nm (manufactured by Creo: TrendSetter 400QTM) with a stepwise change in exposure amount, and a negative PS plate developer made by Okamoto Chemical Co., Ltd. : 1 Development required with an automatic processor (Raptor 85 Thermal (Glunz & Jensen)) with a diluted solution of 1 at a liquid temperature of 30 ° C and a development time of 12 seconds. Necessary for the image to remain completely solid. The minimum exposure was evaluated as sensitivity. The results are shown in Table 1 below.

[Evaluation of scratch resistance]
Each of the above printing plates is exposed with the above-described semiconductor laser at the minimum exposure amount necessary for the image to remain completely solid, and the same as described above with a negative PS plate developer manufactured by Okamoto Chemical Co., Ltd. The image is developed and rubbed with a sponge while washing the image portion with water, and the degree of image loss and the ease of scratching are visually observed. The results are shown in Table 1 below. The evaluation criteria are as follows. ○: Scratches and missing images do not occur. (Triangle | delta): A crack | scratch generate | occur | produces in the sponge-like shape and the image omission of the part generate | occur | produces. X: All images are missing and do not become images.

[Evaluation of printing durability]
Using the semiconductor laser, each printing plate is irradiated with a solid portion and a halftone dot portion with a minimum exposure amount at which the solid portion is completely solid in each plate, and then developed in the same manner as described above, and then each printing plate Got. Next, using a Prisco fountain solution made by mixing 3 ounces of Prisco3451U and 1.5 ounces of AlkalessA6000 in 1 gallon of water, using offset ink (Dai Nippon Ink Chemical Co., Ltd., F gloss ink) Then, print on high-quality paper and count the number of printed sheets until 3% of halftone dots are missing. The results are shown in Table 1 below.

  As is apparent from Table 1, the photosensitive lithographic printing plate of the present invention does not require an overcoat layer, has high sensitivity, excellent adhesion to the support, and is excellent in scratch resistance and printing durability. It is a printing plate for outside laser. In addition, it is thought as follows that a sensitivity, scratch resistance, printing durability, and adhesiveness with a support body improve by adding a diazo resin salt. That is, in a mixed system of a diazo resin salt and an alkali-soluble resin such as a urethane resin, the diazo resin salt is dissolved in an alkaline developer by photolysis and / or thermal decomposition upon exposure with ultraviolet or infrared laser. It becomes difficult to remain as an image. On the other hand, the organoboron compound and the infrared absorber generate a radical upon irradiation with an infrared laser, polymerize a compound having an ethylenic double bond, and make the entire photosensitive layer difficult to dissolve in an alkaline developer. Have. These two synergistic effects increase the speed at which the solubility in an alkaline developer is reduced, and also improve the film strength. This is a phenomenon in which sensitivity is increased, and an increase in film strength leads to improvement in scratch resistance of the photosensitive layer and adhesion to the support, resulting in an increase in printing durability. it is conceivable that.

  For the above reasons, an overcoat layer for increasing sensitivity and preventing scratches is unnecessary, and as a result, it is not affected even in a high-temperature, high-humidity atmosphere, so blocking and sensitivity reduction do not occur. It is done.

Claims (2)

(A) An alkali-soluble resin, (B) a diazo resin salt, (C) a polymerizable compound having two or more ethylenic double bonds, (D) an infrared absorber, and (E) an organic boron salt A photosensitive composition for near-infrared or infrared irradiation, characterized by:
The photosensitive composition further contains an imidazole compound ;
The content of the alkali-soluble resin is 10 to 95% by weight, the content of the diazo resin salt is 1 to 50% by weight, and the ethylenic content is based on the total solid content of the photosensitive composition. The content of the unsaturated compound is 1 to 60% by weight, the content of the infrared absorber is 0.5 to 20.0% by weight, and the content of the organic boron salt is 0.5 to The photosensitive composition having 30.0% by weight and a content of the imidazole compound of 0.5 to 10.0% by weight . A photosensitive lithographic printing plate obtained by providing the photosensitive composition according to claim 1 on a support.