JP5170953B2 - Image forming element and image forming method - Google Patents

Description

  The present invention relates to negative imaging elements that can be exposed by ultraviolet (UV), visible, and infrared (IR) light. In particular, the present invention relates to an imaging element wherein the photosensitive composition of the imaging element comprises a neutralized phosphate ester compound having a (meth) acryloyl group. Furthermore, the present invention provides an image forming method (generally, a machine that removes a non-image portion using dampening water and / or printing ink on a printing machine after the image forming element is image-exposed with an infrared laser. It is said to be top development.)

The latest developments in the field of printing plate precursors deal with radiation sensitive compositions that can be imagewise exposed using lasers or laser diodes. This type of exposure does not require a film as an intermediate information carrier because the laser can be controlled by a computer.
As a light source for light irradiation, a CTP system using, for example, a 488 nm argon ion laser, a 532 nm YAG laser, a high-power semiconductor laser having a maximum intensity in the near infrared or infrared region, and the like has been put into practical use. In particular, solid-state lasers and semiconductor lasers that emit infrared light with a wavelength of 760 nm to 1200 nm have the advantage that the printing plate precursor used in the system can be handled in a bright room, and can easily be high-powered and compact. Is becoming available.

  There are two types of radiation sensitive compositions used to make such printing plate precursors. In the case of a negative printing plate precursor, a photosensitive composition is used in which the exposed area is cured after imagewise exposure. In the development process, only the non-exposed areas are removed from the substrate. In the case of a positive printing plate, a radiation sensitive composition is used such that the exposed areas dissolve faster with the developer than the unexposed areas. This process is called light solubilization.

  It has been conventionally known that a phosphoric acid (meth) acrylate monomer can be used in a photosensitive composition. For example, JP 50-100120 discloses a coating composition comprising a vinyl polymer, a polyfunctional vinyl monomer and a mono-, di- (meth) acryloylalkyl phosphate. This coating composition is an automotive paint. This publication does not describe neutralizing this (meth) acryloyl alkyl phosphate.

  JP-A-58-004138 discloses a photocurable composition having a phosphoric acid compound and indazole having a photopolymerizable unsaturated bond and / or a phthalazone compound. The phosphate compound having the photopolymerizable unsaturated bond is not neutralized, and the photocurable composition must contain an indazole and / or phthalazone compound in order to obtain good adhesion. This photocurable composition is applied to printed wiring of electric circuits.

  Japanese Patent Application Laid-Open No. 10-312055 discloses a photopolymerizable printing plate containing a phosphate ester compound having a (meth) acryloyl group and a pigment. This publication does not describe neutralizing a phosphate ester compound having a (meth) acryloyl group.

  JP-A-11-212253 discloses (a) an addition-polymerizable compound having an ethylenically unsaturated double bond, (b) a sensitizing dye and (c) a polymerization initiator, and (d) an anionic hydrophilic group. Disclosed is a photosensitive composition comprising a containing compound. Although it is described that a phosphate ester is used as the ionic hydrophilic group-containing compound, neutralization of the phosphate ester is not described.

  Japanese Patent Application Laid-Open No. 11-265069 describes that a photopolymerizable printing plate having a protective layer is developed with a silicate developer after laser exposure and then exposed to the entire surface with UV light. Although it is described that the photopolymerizable photosensitive layer may contain a phosphate ester compound having at least one (meth) acryloyl group, it is not described that the phosphate ester compound is neutralized. .

  JP-A-11-030858 discloses a photosensitive composition containing (A) an addition-polymerizable ethylenically unsaturated bond-containing monomer, (B) a photopolymerization initiator, and (C) a polymer binder. A photosensitive lithographic printing plate is disclosed. This addition-polymerizable ethylenically unsaturated bond-containing monomer (A) is described to contain a phosphate ester compound having at least one (meth) acryloyl group. Neutralization is not described.

  Japanese Patent Application Laid-Open No. 2000-235254 discloses that an intermediate layer having a phosphoric acid compound is used in order to improve the adhesion between the image portion of the photopolymerizable printing plate and the substrate. Although this phosphate compound can have an unsaturated double bond, use of this phosphate compound in a photosensitive layer is not described.

  JP 2000-255177 A is a photosensitive lithographic printing plate in which a layer of a photopolymerizable composition is formed on the surface of an aluminum plate support, the aluminum plate support having boehmite and sulfuric acid anodization Disclosed is a photosensitive lithographic printing plate that has been treated, wherein the photopolymerizable composition comprises an acryloyloxy or methacryloyloxyalkyl group-containing phosphate compound. However, this phosphate compound is not neutralized.

  JP 2000-305262 discloses a photosensitive composition comprising an ethylenically unsaturated double bond compound, an infrared absorbing dye and a polymerization initiator, wherein the infrared absorbing dye is a phthalocyanine compound, and is ethylenic. A photosensitive printing plate having a photosensitive composition, wherein the unsaturated double bond compound contains at least a (meth) acryloyloxyalkyl group-containing amine compound and / or a (meth) acryloyloxyalkyl group-containing phosphate compound Describe. However, this version of the phosphate compound is not neutralized.

  JP-A-2000-98602 discloses a photopolymerizable lithographic printing plate comprising a cyanine dye, an ethylenically unsaturated compound comprising a (meth) acryloyloxyalkyl group-containing phosphate compound, a halomethyl group-containing triazine and / or a boron salt initiator. Disclose. This ethylenically unsaturated compound contains an oxyalkyl group in the molecular structure. This ethylenically unsaturated compound is not neutralized.

  Japanese Patent Application Laid-Open No. 2002-214780 describes a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer having an acid value of 25 to 34 and having phosphates having a (meth) acryloyloxy group. These phosphates are not neutralized.

  JP-A-2002-244287 discloses a photosensitive lithographic printing plate having a photopolymerizable photosensitive layer containing a phosphate having an acryloyloxy group or a methacryloyloxy group, a photopolymerization initiation system, and a polymer binder on a substrate. Is described. These phosphates are not neutralized.

  As described above, photosensitive printing plates in which phosphoric acid (meth) acrylate monomer is used for the photopolymerizable photosensitive layer to improve adhesion to the substrate have been used in the past, but these photosensitive compositions are unstable. Therefore, it is known that the stability of the product with time is inferior and the exposure sensitivity is poor. In particular, this photosensitive composition is significantly inferior in stability over time with respect to ionic initiators such as onium salt compounds or boron salt compounds.

Japanese Patent Laid-Open No. 50-100120 JP 58-004138 A Japanese Patent Laid-Open No. 10-312055 Japanese Patent Laid-Open No. 11-212253 Japanese Patent Laid-Open No. 11-265069 Japanese Patent Laid-Open No. 11-030858 JP 2000-235254 A JP 2000-255177 A JP 2000-305262 A Japanese Unexamined Patent Publication No. 2000-98602 JP 2002-214780 A Japanese Patent Laid-Open No. 2002-244287

  The present invention is intended to provide an image-forming element having high exposure sensitivity and excellent temporal stability even when a phosphoric acid (meth) acrylate monomer is used in a photopolymerizable photosensitive layer. In particular, it is an object of the present invention to provide an image forming element that provides a good image even when used together with an ionic initiator such as an onium salt compound or a boron salt compound. Furthermore, the present invention uses the image-forming element as a photosensitive lithographic printing original plate, exposes the image with an infrared laser, and then removes the non-image area using dampening water and / or printing ink on a printing machine. An object of the present invention is to provide an image forming method.

Another object of the invention is an imageable element comprising a substrate and a layer of a photosensitive composition provided on the surface of the substrate,
This is achieved by an imaging element characterized in that the photosensitive composition comprises a neutralized phosphate ester compound having a (meth) acryloyl group.

  According to the present invention, an image forming element having a photosensitive layer having high adhesion to a substrate is provided. The present invention also provides an imaging element that is stable over time and has a long shelf life when used with an ionic initiator such as an onium salt compound or a boron salt compound. Furthermore, according to the present invention, there is provided a method capable of forming an image after image exposure with an infrared laser and then removing non-image areas using dampening water and / or printing ink on a printing press. . The image-forming element of the present invention is particularly preferred as an original plate for lithographic printing.

  The photosensitive composition of this invention contains the neutralized phosphate ester compound which has a (meth) acryloyl group as a polymeric compound. The photosensitive layer containing a neutralized phosphate ester compound having a (meth) acryloyl group used in the present invention undergoes addition polymerization and curing by the action of a photopolymerization initiator when irradiated with activating light. The image-exposed image-forming element is treated with a suitable developer or the like to remove unexposed portions and form a negative image.

  The phosphoric acid ester compound having a (meth) acryloyl group that can be used in the present invention is a phosphoric acid ester having at least one (meth) acryloyl group in the structural formula. It is a phosphoric acid (meth) acrylate monomer.

（式中、R₁は、水素原子またはメチル基、
R₂は、水素原子またはメチル基
nは、１から６の整数である）

(Wherein R ₁ is a hydrogen atom or a methyl group,
R ₂ is a hydrogen atom or a methyl group
n is an integer from 1 to 6)

In the case of taking a phosphate methacrylate structure, the presence of polyalkylene glycol chains such as PEG (polyethylene glycol) chains and PPG (polypropylene glycol) chains in the molecular structure also helps improve the good developability on the printing press. Is preferable. Examples of the compound included in the above structural formula include the following. All of these are sold by Unichemical Corporation.

  In the present invention, these phosphoric acid (meth) acrylate monomers are neutralized using a base. As a neutralization method, 1 to 2 equivalents of a base in terms of mole is added to the phosphoric acid (meth) acrylate monomer. Examples of the base that can be used for neutralization include alkali metal hydroxides, alkaline earth metal hydroxides, and organic amines. Among them, alkali metal hydroxides and hydroxylalkylamines are particularly preferable. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the hydroxylalkylamine include methylhydroxylamine, ethylhydroxylamine, triethanolamine and the like.

  The ratio of the phosphoric acid (meth) acrylate monomer to be neutralized is 5 to 20% by mass with respect to the total solid content constituting the layer made of the photosensitive composition. If it is less than 5% by mass, the adhesion to the substrate is inferior, and ink stains occur in the non-image area due to changes over time. If the ratio of neutralization exceeds 20% by mass, the mechanical strength of the image forming area becomes weak.

  The photosensitive composition of the present invention preferably contains a polymerizable compound other than the phosphoric acid (meth) acrylate monomer as the polymerizable compound. For example, it can be used in the form of a monomer, oligomer, polymer, or a mixture thereof.

  Examples of monomers or oligomers include unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid) and esters and amides thereof, preferably unsaturated carboxylic acids. An ester of an acid and an aliphatic polyhydric alcohol compound and an amide of an unsaturated carboxylic acid and an aliphatic polyamine compound are used.

  In addition, unsaturated carboxylic acid ester having a nucleophilic substituent such as hydroxyl group, amino group, mercapto group, amide and monofunctional or polyfunctional isocyanate, addition reaction product of epoxy, monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used.

  In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an isocyanate group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, halogen A substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a group or a tosyloxy group with a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. Moreover, the compound group replaced by unsaturated phosphonic acid, styrene, etc. can also be used instead of said unsaturated carboxylic acid.

  Specific examples of the radical polymerizable compound that is an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol methyl ether acrylate, 1, 3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate Acrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pen Erythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri ( Acryloyloxyethyl) isocyanurate, polyester acrylate oligomers and the like.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol methyl ether methacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3 -Butanediol dimethacrylate, hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate Rate, sorbitol tetramethacrylate, bis [p- (3--methacryloxy-2-hydroxypropoxy) phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

  Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.

  Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.

  Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, JP-A-59-5241. Those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used.

  Specific examples of the radical polymerizable compound that is an amide of an aliphatic polyvalent amine compound and an unsaturated carboxylic acid include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6 -Hexamethylene bis-methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. In the polyisocyanate compound having two or more isocyanate groups, CH ₂ ═C (R ¹ ) COOCH ₂ CH (R ² ) OH (where R ¹ and R ² are each independently H or CH ₃ . And a vinylurethane compound containing two or more polymerizable vinyl groups in one molecule to which a vinyl monomer containing a hydroxyl group represented by (1) is added.

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765, JP-B-58-49860, JP-B-56-17654, Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable.

  Furthermore, radical polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 may be used. In addition, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, and JP-B-1-40336, and vinylphosphonic acid compounds described in JP-A-2-25493 can also be exemplified. . In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, those introduced as photocurable monomers and oligomers in Journal of Japan Adhesion Association vol. 20, No. 7, pages 300 to 308 (1984) can also be used.

  Examples of the radical polymerizable compound having at least one ethylenically unsaturated double bond of the polymer type include, for example, JP-A-48-64183 and JP-B-49-43191 in addition to the above-mentioned monomer or oligomer polymer. Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid, as described in JP-B-52-30490, each publication.

  The polymerizable compound of the present invention makes the photosensitive composition insoluble in wet developer or dampening water / printing ink after exposure to radiation such as ultraviolet (UV), visible light, and infrared (IR). As such, it is present in a sufficient amount in the photosensitive composition. Specifically, it is preferably 5 to 80% by mass, more preferably 10 to 70% by mass, based on all components of the photosensitive composition.

  The photosensitive composition of the present invention preferably contains the polymerizable compound described above and a photopolymerization initiator for generating initiating free radicals. Any photopolymerization initiator can be used as long as it can initiate polymerization of the above-described polymerizable compound. Photoinitiators that are active against electromagnetic radiation in the ultraviolet, visible, and / or infrared spectral ranges corresponding to a spectral range of about 300-1400 nm can be used. Such photoinitiator systems include, for example, trichloromethyltriazine present alone or with a photosensitizer, as described in US Pat. No. 4,997,745; in US Pat. No. 5,546,258. Diaryliodonium salts and photosensitizers as described; spectral sensitizers for visible light activation present with trichloromethyltriazine, as described, for example, in US Pat. No. 5,599,650; Polycarboxylic acid coinitiators such as anilino-N, N-2 acetic acid as described in US Pat. No. 5,942,372, diaryliodonium salts, titanocene, haloalkyltriazines, hexaarylbisimidizole, boric acid Secondary co-initiation such as salts and photooxidants containing heterocyclic nitrogen atoms substituted by alkoxy or acyloxy groups 3-ketocoumarin for UV and visible light activation present with: cyanine dyes, diaryliodonium salts, and N directly attached to an aromatic ring, as described in US Pat. No. 5,368,990, A co-initiator having a carboxylic acid group attached to the O or S group via a methylene group; infrared, as described in US Pat. No. 5,496,903, with trichloromethyltriazine and an organoboron salt Cyanine dyes for activity; compounds capable of generating initiating free radicals, including infrared absorbers, trichloromethyltriazine and azinium compounds, as described in US Pat. No. 6,309,792, directly on the aromatic ring A polycarboxylic acid coinitiator having a carboxylic acid group bonded to a bonded N, O, S group via a methylene group Murrell.

  In the present invention, a boron salt compound or an onium salt compound can be suitably used as a photopolymerization initiator in combination with a neutralized phosphoric acid (meth) acrylate monomer. When these ionic initiators are used together with conventional phosphoric acid (meth) acrylate, the ionic form is destroyed by phosphoric acid over time, making the printing plate precursor unstable and shortening the shelf life. was there. Such a problem is solved by using the neutralized phosphoric acid (meth) acrylate monomer of the present invention. These photopolymerization initiators may be used alone or in combination of two or more.

  A boron salt compound expresses the function as a polymerization initiator by using together with an infrared absorber. As the boron salt compound, an ammonium salt of a quaternary boron anion represented by the following formula (1) is preferable.

(Wherein R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently an alkyl group, aryl group, alkaryl group, allyl group, aralkyl group, alkenyl group, alkynyl group, alicyclic group, or saturated. Or an unsaturated heterocyclic group, wherein at least one of R ¹ , R ² , R ³ and R ⁴ is an alkyl group having 1 to 8 carbon atoms, and R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ each independently represents a hydrogen atom, an alkyl group, an aryl group, an allyl group, an alkaryl group, an aralkyl group, an alkenyl group, an alkynyl group, an alicyclic group, or a saturated or unsaturated heterocyclic group. )

  Among these, tetra-n-butylammonium triphenyl boron, tetra-n-butylammonium trinaphthyl boron, tetra-n-butylammonium tri (pt-butylphenyl) boron, tetramethylammonium are able to exhibit the polymerization function efficiently. n-butyltriphenylboron, tetramethylammonium n-butyltrinaphthylboron, tetramethylammonium n-octyltriphenylboron, tetramethylammonium n-octyltrinaphthylboron, tetraethylammonium n-butyltriphenylboron, tetraethylammonium n- Butyl trinaphthyl boron, trimethyl hydrogen ammonium n-butyl triphenyl boron, triethyl hydrogen ammonium n-butyl triphenyl boron, tetra high B Gen ammonium n- butyl triphenyl borate, tetramethylammonium n- butylboron, etc. tetraethylammonium n- butylboron can be preferably used.

  When the boron salt compound is used in combination with an infrared absorber, radicals are generated by irradiation with infrared rays, and a function as a polymerization initiator can be exhibited.

  The content of the boron salt compound is preferably in the range of 0.1 to 15% by mass, particularly preferably in the range of 0.5 to 7% by mass, based on the solid content of the photosensitive layer. When the content of the boron salt compound is less than 0.1% by mass, the polymerization reaction becomes insufficient, the curing is insufficient, and the image portion of the obtained negative photosensitive lithographic printing plate becomes weak, and the content of the boron salt compound When the content exceeds 15% by mass, the polymerization reaction does not occur efficiently. Moreover, you may use together 2 or more types of (B) boron salt compounds as needed.

An onium salt compound is a salt composed of a cation having one or more onium ion atoms in the molecule and an anion. The onium ion atom in the onium salt, S ⁺ in sulfonium, iodonium of I ^+, N ⁺ in ammonium, P ⁺ atom in phosphonium, may be mentioned N ₂ ⁺ and diazonium. Among these, as preferable onium ion atoms, S ⁺ , I ⁺ and N ₂ ⁺ can be fisted. The structure of the onium salt compound includes triphenylsulfonium, diphenyliodonium, diphenyldiazonium, derivatives in which alkyl groups and aryl groups are introduced into the benzene ring of these compounds, and alkyl groups and aryl groups in the benzene ring of the compound. The introduced derivative can be fisted.

Examples of the anion of the onium salt compound include a halogen anion, ClO ₄ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₆ H ₅ SO ₃ ⁻ and CH _3. C ₆ H ₄ SO ₃ ⁻ , HOC ₆ H ₄ SO ₃ ⁻ , ClC ₆ H ₄ SO ₃ ⁻ , boron anion and the like can be mentioned.

As the onium salt compound, a combination of an onium salt having S ⁺ in the molecule and an onium salt having I ⁺ in the molecule is preferable from the viewpoint of sensitivity and storage stability. Moreover, as an onium salt, the polyvalent onium salt which has a 2 or more onium ion atom in 1 molecule from the point of a sensitivity and storage stability is also preferable. Here, two or more onium ion atoms in the cation are linked by a covalent bond. Among polyvalent onium salts, those having two or more onium ion atoms in one molecule are preferable, and those having S ⁺ and I ⁺ in one molecule are more preferable.

  The content of the onium salt compound is preferably in the range of 0.1 to 15% by mass, particularly preferably in the range of 0.5 to 7% by mass, based on the solid content of the photosensitive layer. If the content of the onium salt compound is less than 0.1% by mass, the polymerization reaction may be insufficient, and the sensitivity and rigidity resistance of the obtained negative photosensitive lithographic printing plate may be insufficient. When the amount exceeds 15% by mass, the developability of the obtained negative photosensitive lithographic printing plate is deteriorated. Moreover, you may use together 2 or more types of onium salt compounds as needed. Moreover, you may use together a polyvalent onium salt compound and a monovalent onium salt compound.

  Moreover, you may add arbitrary promoters, such as mercapto compounds, such as a mercapto-3-triazole, and an amine compound, to a photoinitiator.

Preferred photoinitiator systems include ultraviolet, visible, or infrared absorbers, electron acceptors capable of generating initiating free radicals, and can donate electrons and / or hydrogen atoms and / or initiation free. Co-initiators that can form radicals are included. The amount of the radiation absorber is an amount required for the photosensitive composition to become insoluble in a wet developer or dampening water / printing ink after exposure to radiation. The concentration of the radiation absorber is about 0.05 to 3 mol l ⁻¹ cm ⁻¹ , preferably about 0.1 to 1.5 mol l ⁻¹ cm ⁻¹ , more preferably 0.3 to 1.0 mol. It is preferable that the molar absorptivity within the range of l ^-1 cm ^-1 is obtained.

  Preferred infrared absorbers for light / thermal activation are squarylium dyes, croconate dyes, triarylamine dyes, thiazolium dyes, indolium dyes, oxazolium dyes, cyanine and merocyanine dyes, polyaniline dyes, polypyrrole dyes, polythiophene dyes, chalcogenopyrim dyes. Lower arylene and bis (chalcogenopyrrillo) polymethine dyes, oxyindolizine dyes, pyrylium dyes, and phthalocyanine pigments. Other useful classes include azulenium and xanthene dyes, as well as carbon black, metal carbides, borides, nitrides, carbonitrides, and bronze structured oxides.

Among these, as the infrared absorber, a near-infrared absorbing cation dye represented by the following formula is preferable because the photopolymerization initiator efficiently exhibits a polymerization function.

(In the formula, D ⁺ represents a cationic dye having absorption in the near infrared region, and A ⁻ represents an anion.)

  Examples of cationic dyes having absorption in the near infrared region include cyanine dyes, triarylmethane dyes, aminium dyes, diimmonium dyes, and dyes having absorption in the near infrared region. As specific examples of the cationic dye having absorption in the near infrared region, the following can be used.

As anions, halogen anions, ClO ₄ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₆ H ₅ SO ₃ ⁻ , CH ₃ C ₆ H ₄ SO ₃ ⁻ , HOC ₆ H ₄ SO ₃ ⁻ , ClC ₆ H ₄ SO ₃ ⁻ , and the quaternary boron anion include a boron anion represented by the above formula (1). As the boron anion, triphenyl n-butylboron anion and trinaphthyl n-butylboron anion are preferable.

  When using a pigment | dye as an infrared absorber, the range of 0.5-15 mass% is preferable with respect to the total solid of a photosensitive composition, and the range of 1-10 mass% is especially preferable. . When the pigment content is less than 0.5% by mass, the infrared absorption is insufficient. When the pigment content exceeds 15% by mass, the infrared absorption substantially reaches saturation, and the effect of addition is improved. It is not preferable because it tends to be absent.

  As the binder resin, when an alkaline developer is used, an organic high molecular polymer that is soluble or swellable in alkaline water is preferably used. Examples of the organic polymer that is soluble or swellable in alkaline water include various polymers. However, those having an alkali-soluble group (acid group) in the main chain or side chain are preferred. As the acid group, an acid group having a pKa of 0 to 12 or less is preferable, and particularly active amino and imino groups represented by carboxylic acid group, phenolic hydroxyl group, sulfonamide group, N-sulfonylcarbamoyl group, N-acylcarbamoyl group and the like are more preferable. preferable. Examples of such an organic polymer include addition polymers having a carboxylic acid group in the side chain, such as JP-A-59-44615, JP-B-54-34327, JP-B-58-12577, JP-B-54- 25957, JP-A-54-92723, JP-A-59-53836, JP-A-59-71048, ie, methacrylic acid copolymer, acrylic acid copolymer, itacon Cyclic acid anhydrides for acid copolymers, crotonic acid copolymers, maleic acid copolymers, partially esterified maleic acid copolymers, acidic cellulose derivatives having a carboxylic acid group in the side chain, and addition polymers having a hydroxyl group Such as polyvinyl pyrrolidone, polyethylene oxide, alcohol-soluble polyamide that can increase the strength of the cured film, and polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin. Can fist . Among these, [benzyl (meth) acrylate / (meth) acrylic acid / other addition-polymerizable vinyl monomers as required] copolymer and [allyl (meth) acrylate / (meth) acrylic acid / as required Other addition polymerizable vinyl monomers] copolymers are particularly preferred. Furthermore, Japanese Patent Publication No. 7-120040, Japanese Patent Publication No. 7-142004, Japanese Patent Publication No. 7-142004, Japanese Patent Publication No. 8-12424, Japanese Patent Publication No. Sho 63-287944, Japanese Patent Publication No. Sho 63-287947, Japanese Patent Publication No. Hei 1 -271741 and JP-A-11-352691 can also be used for the application of the present invention.

  These polymer polymers can improve the strength of the film formed from the binder resin by introducing a radical reactive group into the side chain. Functional groups capable of addition polymerization reaction include ethylenically unsaturated bond groups, amino groups, epoxy groups, etc., and functional groups that can become radicals by light irradiation include mercapto groups, thiol groups. , Halogen atoms, triazine structures, onium salt structures and the like, and polar groups include carboxyl groups and imide groups. As the functional group capable of undergoing the addition polymerization reaction, an ethylenically unsaturated bond group such as an acryl group, a methacryl group, an allyl group, or a styryl group is particularly preferable. A functional group selected from a galvamoyl group, an isocyanate group, a ureido group, a ureylene group, a sulfonic acid group, and an ammonio group can also be used.

  In order to maintain the developability of the photosensitive lithographic printing plate, the binder resin used preferably has an appropriate molecular weight and acid value. The weight average molecular weight is 5,000 to 300,000, the acid value is 20 to 200 (KOHmg / g-resin) is particularly preferred. These binder resins can be contained in an arbitrary amount in the photosensitive layer. However, when the amount exceeds 90% by mass, a favorable result is not given in terms of the strength of an image formed using the layer. There is a case. A preferable amount is 10 to 90% by mass, more preferably 30 to 80% by mass. The ratio of the photopolymerizable compound and the binder resin used is preferably 1/9 to 9/1 in terms of mass ratio, more preferably 2/8 to 8/2, and most preferably 3. / 7 to 7/3.

  On-machine development type that removes the non-image part of the printing original plate by supplying the dampening water and ink while rotating the cylinder without performing development processing after image formation. In the case of a high molecular polymer that is developed using a neutral developer after formation, a graft polymer having an alkylene oxide chain in the side chain and a floc copolymer having an alkylene oxide chain in the main chain are preferably used. . The alkylene oxide chain is preferably a polyoxyethylene unit or a polyoxyethylene / polyoxypropylene unit. For example, a copolymer of polyethylene glycol monomethacrylate and other unsaturated group-containing compound can be fisted.

  Here, as a graft polymer suitably used, a polymer having a hydrophilic alkylene oxide chain and a hydrophobic group in the side chain of the polymer can be used. As the hydrophobic group, a cyano group, a phenyl group, an amide group, a substituted phenyl group, an alkyl ester group, a substituted alkyl ester group, and the like can be used. This substituted phenyl group includes those in which hydrogen of an aromatic ring is condensed with another alkyl group, a hetero atom, a modifying group starting from a hetero atom, or a plurality of aromatic rings. In addition, the substituted alkyl group itself may form a ring. The structure of the alkyl ester group is represented by the following formula.

(In the above formula, R is an alkyl or cycloalkyl group which may have a substituent. The side chain is bonded to the binder main chain via a carbonyl group (C═O).)

  Here, the polyalkylene oxide chain indicates one having a polyalkylene oxide segment. In general, most of them are composed of polyalkylene oxide segments, and can also have a linking group and a terminal group. The polyalkylene oxide segment represents an oligomer or polymer containing a block of an alkylene oxide structural unit.

The alkylene oxide structural unit is specifically a (C ₁ -C ₆ ) alkylene oxide group, and more specifically a (C ₁ -C ₃ ) alkylene oxide group. Therefore, the polyalkylene oxide segment is represented by — (CH ₂ —O—), — (CH ₂ CH ₂ —O—), — (CH (CH ₃ ) —O—), — (CH ₂ CH ₂ CH ₂ —O). -),-(CH (CH ₃ ) CH ₂ -O-),-(CH ₂ CH (CH ₃ ) -O-), or combinations thereof, a straight chain having 1 to 3 carbon atoms or A side chain alkylene oxide group can be mentioned. Among these, it is more preferable to have a — (CH ₂ CH ₂ —O—) structural unit.
The number average molecular weight of the alkylene oxide unit is preferably from 100 to 100,000, more preferably from 500 to 10,000.

Specific examples of the polyalkylene oxide chain include the following.
-C (= O) O - ( (CH 2) x O) y -R,
Here, x represents 1 to 3, y represents 5 to 180, and R represents a terminal group. Although there is no restriction | limiting in R, It is preferable to use the alkyl group which has a hydrogen atom and 1-6 carbon atoms. Specific examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, and neo-pentyl. Group, n-hexyl group, isohexyl group, 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, cyclopentyl group, and cyclohexyl group are used.

The following is preferably used as the polyalkylene oxide chain.
-C (= O) O- (CH 2 CH 2 O) y -CH 3,
Here, y is 12-200, More preferably, it is 25-75. More preferably, y is 40-50.

  Examples of the copolymer component include cyano group-containing monomers, acrylic acid esters, methacrylic acid esters, styrene, hydroxystyrene, acrylic acid, and methacrylic acid. Preferable examples include acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene and derivatives thereof, methyl methacrylate, or allyl methacrylate derivatives.

As one specific example of the binder resin, one constituted by a monomer and / or macromer copolymer component as shown below can be cited.
Copolymerization component A) Acrylonitrile, methacrylonitrile, or mixtures thereof.
Copolymerization component B) A poly (alkylene glycol) ester of acrylic acid or methacrylic acid such as poly (ethylene glycol) methyl ether acrylate or poly (ethylene glycol) methyl ether methacrylate.
Copolymerization component C) If necessary, a monomer such as styrene or methacrylamide or a mixture of monomers.

  The copolymerization component A) is preferably 20% to 95% in the composition, more preferably 50% to 90%. The copolymerization component B) is preferably 1% to 40% in the composition, more preferably 4% to 30%. The copolymerization component C) is preferably 4% to 40%, more preferably 6% to 30% in the composition.

  Macromers B of copolymerization component B) are, for example, polyethylene glycol monomethacrylate and polypropylene glycol methyl ether methacrylate, polyethylene glycol ethyl ether methacrylate, polyethylene glycol butyl ether methacrylate, polypropylene glycol hexyl ether methacrylate, polypropylene glycol octyl ether methacrylate, polyethylene glycol methyl. Ether acrylate, polyethylene glycol ethyl ether acrylate, polyethylene glycol phenyl ether acrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, polypropylene glycol methyl ether methacrylate, polypropylene Recall ethyl ether methacrylate, polypropylene glycol butyl ether methacrylate, polyethylene glycol / propylene glycol methyl ether methacrylate, poly (vinyl alcohol) monomethacrylate, and polyvinyl alcohol monoacrylate or mixtures thereof.

  As the monomer B, poly (ethylene glycol) methyl ether methacrylate, poly (ethylene glycol) acrylate, poly (propylene glycol) methyl ether methacrylate, or a mixture thereof can be generally used.

  Examples of the monomer C include acrylic acid, methacrylic acid, acrylic ester, methacrylic ester such as methyl methacrylate, allyl methacrylate, hydroxyethyl methacrylate, styrene, hydroxystyrene, acrylamide, methacrylamide, or a combination thereof. I can fist. Among these, styrene, methacrylamide, or derivatives thereof are more preferable.

  Specifically, styrene, 3-methylstyrene, 4-methylstyrene, 4-methoxystyrene, 4-acetoxystyrene, α-methylstyrene, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, n-hexyl Acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylic acid, n-pentyl methacrylate, neo-pentyl methacrylate, cyclohexyl methacrylate, n-hexyl methacrylate and 2-ethoxyethyl methacrylate, 3- Methoxypropyl methacrylate, allyl methacrylate, vinyl acetate, vinyl butyrate, methyl vinyl ketone, butyl vinyl ketone, vinyl fluoride, vinyl chloride, vinyl bromide, maleic anhydride, maleimide, N-phenylmale Mention may be made of imides, N-cyclohexylmaleimide, N-benzylmaleimide and mixtures.

  These monomers are synthesized by a known radical polymerization method, and a commonly used known initiator such as azobisisobutyronitrile (AIBN) is preferably used as the polymerization initiator.

  As the solvent in which radical polymerization is performed, a liquid that is inert to the reactants and does not adversely affect the reaction is used. Specifically, esters such as ethyl acetate, butyl acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone and acetone, alcohols such as methanol, ethanol, isopropyl alcohol and butanol, such as dioxane and tetrahydrofuran Ether, water, and mixtures thereof can be used.

  In addition to the binder resin, one or more secondary binder resins may be included. As the auxiliary binder resin, a water-soluble or water-dispersed polymer is used. For example, carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, cellulose derivatives such as hydroxyethylcellulose, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyvinylpyrrolidone, polylactide, polyvinylphosphonic acid, synthetic copolymers, and mixtures thereof Can be mentioned. Examples of the synthetic copolymer include a copolymer of an alkoxy polyethylene glycol (meth) acrylate such as methoxypolyethylene glycol (meth) acrylate and a monomer such as methyl (meth) acrylate, butyl (meth) acrylate, and allyl methacrylate. Can be mentioned.

  It is desirable to add a small amount of a thermal polymerization inhibitor to the photosensitive composition of the present invention in order to prevent unnecessary thermal polymerization of the photopolymerizable compound during the production or storage of the photosensitive composition. Preferred thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-t-butylphenol) 2,2′-methylenebis (4-methyl-6-t-butylphenol), N-nitrosophenylhydroxylamine cerium salt, N-nitrosophenylhydroxylamine aluminum salt, and the like. The amount of this type of thermal polymerization inhibitor added is preferably about 0.01% by mass to about 5% by mass of the total components of the photosensitive composition. Also, if necessary, in order to prevent polymerization inhibition by oxygen, higher fatty acid derivatives such as behenic acid and behenamide are added and unevenly distributed on the surface of the photopolymerizable photosensitive layer in the process of drying after coating. You may let them. The addition amount of the higher fatty acid derivative is preferably 0.5 to 10% by mass of the total components of the photosensitive composition.

  Further, a coloring agent may be added for the purpose of coloring the photosensitive composition. Examples of the colorant include phthalocyanine pigments (CIPigment Blue 15: 3, 15: 4, 15: 6 etc.), azo pigments, pigments such as carbon black and titanium oxide, ethyl violet, crystal violet, azo dyes and anthraquinones. System dyes and cyanine dyes. The addition amount of the dye and the pigment is preferably about 0.5% by mass to about 5% by mass of the total components of the photosensitive composition.

  In order to improve the physical properties of the cured film obtained from the photosensitive layer, additives such as inorganic fillers and plasticizers such as dioctyl phthalate, dimethyl phthalate, and tricresyl phosphate may be added. For the purpose of improving the coating properties of the coating surface, known surfactants to which a known surfactant may be added include fluorine-based surfactants, polyoxyalkylene alkyl ether-based nonionic surfactants, Examples thereof include silicon-based surfactants such as dialkylsiloxane.

  The image-forming element of the present invention comprises a photosensitive layer made of the above-described photosensitive composition on a substrate that has been subjected to various surface treatments described below as required. The photosensitive layer can be obtained by dissolving the photosensitive composition described above in various organic solvents and applying the solution on a substrate. The imaging element of the present invention is preferably negative-working.

  Solvents that can be used in the present invention include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, dimethyl ether, diethyl ether, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl. Ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 3-methoxypropanol, methoxymethoxyethanol , Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethylformamide, dimethyl sulfoxide, γ- Examples include butyrolactone, methyl lactate, ethyl lactate, methanol, ethanol, propanol, butanol, and water. These solvents can be used alone or in combination. In addition, 1-50 mass% is suitable for solid content concentration in a coating solution.

The coating amount of the photosensitive layer in the imaging element of this invention is in the range of 0.1 to 10 g / m ² in weight after coating and drying are suitable, more preferably from 0.3 to 5 g / m ^2, further preferably from 0.5 to 3 g / m ^2.

  Since the image-forming element of the present invention is usually exposed in the air, it is preferable to further provide a protective layer on the photosensitive layer. The protective layer prevents exposure of low molecular compounds such as oxygen and basic substances present in the atmosphere that inhibit the polymerization reaction in the photosensitive layer to the photosensitive layer, and facilitates exposure conditions in the air. Properties desired for such a protective layer are low permeability of low-molecular compounds such as oxygen, furthermore, good transparency of the irradiation light used for exposure, excellent adhesion to the photosensitive layer, and It can be easily removed during development.

  As a material for the protective layer, for example, a water-soluble polymer compound having relatively excellent crystallinity can be used. Specifically, polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, Such as acrylic acid. Of these, the use of polyvinyl alcohol as the main component gives the best results for basic properties such as oxygen barrier properties and development removability. The polyvinyl alcohol used for the protective layer may be partially substituted with an ester, an ether and an acetal as long as it contains an unsubstituted vinyl alcohol unit for having necessary oxygen barrier properties and water solubility. Similarly, some of them may have other copolymer components.

  As a specific example of polyvinyl alcohol (PVA), those having a hydrolysis rate of 71 to 100% and a molecular weight in the range of 300 to 2400 can be fisted. Specifically, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, manufactured by Kuraray Co., Ltd. PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, PVA-L8 and the like.

  The components of the protective layer (selection of PVA type, use of additives, etc.), coating amount, etc. are selected in consideration of fogging, adhesion, and scratch resistance in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of the PVA used (the higher the content of unsubstituted vinyl alcohol units in the protective layer), the thicker the film thickness, the higher the oxygen barrier property, which is advantageous in terms of sensitivity. . However, when the oxygen barrier property is extremely increased, problems such as unnecessary polymerization reaction during production and storage, and unnecessary fogging and image line weighting during exposure occur. In addition, adhesion to the image area and scratch resistance are extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on an oleophilic polymer layer, film peeling due to insufficient adhesion tends to occur, and the peeled portion causes defects such as poor film hardening due to inhibition of oxygen polymerization. As a method for improving the adhesion between two layers, a method of mixing 20 to 60% by mass of an acrylic emulsion or a water-insoluble vinylpyrrolidone-vinyl acetate copolymer in a hydrophilic polymer composed of polyvinyl alcohol is mainly mentioned. be able to.

  Any substrate can be used as long as the surface of the image forming element of the present invention is hydrophilic, but a dimensionally stable plate-like material is preferable, for example, paper, plastic (for example, polyethylene, polypropylene, Paper laminated with polystyrene, etc., and also metals such as aluminum (including aluminum alloys), zinc, copper, etc. or alloys thereof (eg silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, A plate of an alloy with nickel), and further, for example, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose butyrate acetate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc. Plastic Irumu, the above described metal or alloy can be cited laminated or vapor-deposited paper or plastic films. Of these substrates, an aluminum plate is particularly preferred because it is extremely dimensionally stable and inexpensive. Further, a composite sheet in which an aluminum sheet is bonded on a polyethylene terephthalate film as described in Japanese Patent Publication No. 48-18327 is also preferable. Usually, the thickness is about 0.05 mm to 1 mm.

  In the case of a substrate having a surface of metal, particularly aluminum, surface treatment such as graining treatment, anodizing treatment described later, or immersion treatment in an aqueous solution of sodium silicate, potassium fluoride zirconate, phosphate, etc. It is preferable that

Examples of the graining method include mechanical graining, chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. Furthermore, electrochemical graining method that electrochemically grains in hydrochloric acid or nitric acid electrolyte solution, and wire brush grain method that scratches aluminum surface with metal wire, and ball grain method that graines aluminum surface with polishing ball and abrasive. Further, a mechanical graining method such as a brush grain method in which the surface is grained with a nylon brush and an abrasive can be used, and the above graining methods can be used alone or in combination. Among them, the method of making the surface roughness usefully used in the present invention is an electrochemical method of graining chemically in hydrochloric acid or nitric acid electrolyte, and a suitable current density is in the range of 100 to 400 C / dm ² . It is. More specifically, electrolysis is performed in an electrolytic solution containing 0.1 to 50% hydrochloric acid or nitric acid at a temperature of 20 to 100 ° C., a time of 1 second to 30 minutes, and a current density of 100 to 400 C / dm ^2. Is preferred.

  The grained aluminum substrate is chemically etched with acid or alkali. When an acid is used as an etching agent, it takes time to destroy the fine structure, which is disadvantageous when the present invention is applied industrially, but it can be improved by using an alkali as the etching agent.

Examples of the alkali agent suitably used include caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide and the like, and preferred ranges of concentration and temperature are 1 to 3, respectively. The conditions are 50%, 20 to 100 ° C., and the amount of aluminum dissolved is 5 to 20 g / m ³ .

  After etching, pickling is performed to remove dirt (smut) remaining on the surface. Examples of the acid that can be used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid. In particular, as a method for removing smut after the electrochemical surface roughening treatment, contact with 15 to 65 mass% sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739 is preferable. And the alkali etching method described in Japanese Patent Publication No. 48-28123. In addition, the surface roughness (Ra) of the aluminum base preferable in the present invention is 0.3 to 0.7 μm.

The aluminum substrate treated as described above is further anodized. The anodizing treatment can be performed by a method conventionally performed in the technical field. Specifically, sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzene sulfonic acid, etc., or a combination of two or more thereof, and when direct current or alternating current is passed through aluminum in an aqueous solution or non-aqueous solution, an aluminum substrate An anodized film can be formed on the surface. The conditions of the anodizing treatment cannot be determined unconditionally because they vary depending on the electrolytic solution used. In general, the concentration of the electrolytic solution is 1 to 80%, the liquid temperature is 5 to 70 ° C., the current density is 0.00. A range of 5 to 60 amperes / dm ² , a voltage of 1 to 100 V, and an electrolysis time of 10 to 100 seconds is appropriate.

  Among these anodizing treatments, a method of anodizing at a high current density in sulfuric acid described in British Patent 1,412,768, and phosphoric acid described in U.S. Pat. A method of anodizing as an electrolytic bath is preferred.

In the present invention, the anodized film is preferably from ^{1~10g / m 2, 1g / m} 2 less than the plate to easily enter the wound to be, requires significant power production exceeds 10 g / m ² It is economically disadvantageous. Preferably, it is 1.5-7 g / m < ² >, More preferably, it is 2-5 g / m < ² >.

  In the present invention, the substrate may be subjected to sealing treatment after graining treatment and anodizing. Such sealing treatment is performed by immersing the substrate in a hot aqueous solution containing hot water and an inorganic salt or an organic salt, a steam bath, or the like. The substrate used in the present invention is treated with silicate treatment with alkali metal silicate, treatment with potassium fluorozirconate, treatment with an aqueous solution of polyaminesulfonic acid, polyvinylphosphonic acid, polyacrylic acid, or polymethacrylic acid. Surface treatment such as may be performed.

  In the present invention, a photosensitive layer made of the above-described photosensitive composition is applied on a substrate (in the case of aluminum, aluminum that has been appropriately surface-treated as described above), and further protected as necessary. By applying the layer, an imaging element is formed. Since the photosensitive composition of the present invention has very good adhesion to the substrate, it is not necessary to provide an organic or inorganic undercoat layer between the photosensitive layer and the substrate, but it may be provided if necessary. Although not necessary, a sol-gel treatment in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A-7-159983 is covalently bonded may be applied.

  The image forming element can be developed after being directly exposed to an Ar laser, a second harmonic of a semiconductor laser (SHG-LD, 350 to 600 nm), a YAG-SHG laser, an lnGa N-based short wave semiconductor laser, or the like. In order to enable handling in a bright room, it is preferable to use a high-power laser having the maximum intensity from the near infrared to the infrared region. As such a laser having the maximum intensity from the near infrared to the infrared region, various lasers having the maximum intensity in the wavelength region of 760 to 1200 nm are used. In addition, you may provide the heating process for the time for 1 second-5 minutes at the temperature of 50 to 150 degreeC for the purpose of raising the hardening rate of a photopolymerizable photosensitive layer after image exposure and development.

  As a developing solution used in the development processing, a conventionally known alkaline aqueous solution can be used. For example, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium Inorganic alkaline agents such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium and lithium can be mentioned. Also, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, ethylene An organic alkali agent such as imine, ethylenediamine, or pyridine may be used in combination. These alkali agents may be used alone or in combination of two or more.

  Further, the surfactant described below may be added to the developer. Examples of the developer surfactant include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene stearyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, and the like. Polyoxyethylene alkyl allyl ethers, polyoxyethylene alkyl esters such as polyoxyethylene stearate, sorbitan monolaurate, sorbitan monostearate, sorbitan distearate, sorbitan monooleate, sorbitan sesquioleate, sorbitan Monoglyceride alkyl esters such as sorbitan alkyl esters such as trioleate, glycerol monostearate and glycerol monooleate Nonionic surfactants such as alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, alkylnaphthalenesulfonic acids such as sodium butylnaphthalenesulfonate, sodium pentylnaphthalenesulfonate, sodium hexylnaphthalenesulfonate, sodium octylnaphthalenesulfonate Anionic surfactants such as salts, alkyl sulfates such as sodium lauryl sulfate, alkyl sulfonates such as sodium dodecyl sulfonate, sulfosuccinate ester salts such as sodium dilauryl sulfosuccinate: alkyl betaines such as lauryl betaine and stearyl betaine Amphoteric surfactants such as amino acids can be used, but anionic surfactants such as alkylnaphthalene sulfonates, alkyls are particularly preferable. Tines such a nonionic surfactant having a polyoxyalkylene ether group represented by the formula (2).

R ¹ —O— (R ² —O) _n H (2)
{In Formula (2), R ¹ is an optionally substituted alkyl group having 3 to 15 carbon atoms, an optionally substituted aromatic hydrocarbon group having 6 to 15 carbon atoms, or a substituent. A heteroaromatic cyclic group having 4 to 15 carbon atoms which may have an alkyl group (the substituent is an alkyl group having 1 to 20 carbon atoms, a halogen atom such as Br, Cl or I, an aromatic group having 6 to 15 carbon atoms) A hydrocarbon group, an aralkyl group having 7 to 17 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, and an acyl group having 2 to 15 carbon atoms). R ² represents an optionally substituted alkylene group having 1 to 10 carbon atoms (the substituent includes an alkyl group having 1 to 20 carbon atoms and an aromatic hydrocarbon group having 6 to 15 carbon atoms. And n represents an integer of 1 to 100}. In addition, the (R ² —O) _n portion of the formula (2) may be two or three groups as long as it is in the above range. Specific examples include a combination of random or flocked combinations of ethyleneoxy and propyleneoxy, ethyleneoxy and isopropyloxy, ethyleneoxy and butyleneoxy, ethyleneoxy and isobutylene, etc. it can.

  These surfactants can be used alone or in combination. Further, the content of these surfactants in the developer is preferably from 0.1 to 20% by mass in terms of active ingredients.

  In the present invention, in addition to the above components, the following components can be used in combination with the developer as necessary. For example, benzoic acid, phthalic acid, p-ethylbenzoic acid, pn-propylbenzoic acid, p-isopropylbenzoic acid, pn-butylbenzoic acid, pt-butylbenzoic acid, p-2-hydroxyethylbenzoic acid Organic carboxylic acids such as acid, decanoic acid, salicylic acid, 3-hydroxy-2-naphthoic acid; organic solvents such as isopropyl alcohol, benzyl alcohol, ethyl cellosolve, butyl cellosolve, phenyl cellosolve, propylene glycol, diacetone alcohol; Agents, reducing agents, dyes, pigments, water softeners, preservatives, antifoaming agents and the like.

  The image forming element of the present invention is developed with the developer according to a conventional method, for example, by immersing an exposed lithographic printing plate in the developer at a temperature of 0 to 60 ° C., preferably about 15 to 40 ° C. For example, rubbing with. Furthermore, development processing may be performed using an automatic developing machine, in which case the developer will be fatigued depending on the amount of processing, so that replenisher or fresh developer may be used to restore processing capacity. May be. When a protective layer is provided on the photosensitive layer, the protective layer may be removed and the unexposed portion of the photosensitive layer may be removed at the same time using the developer described above, or water, warm water The protective layer may be removed first, and then the unexposed photosensitive layer may be removed with a developer. These water or warm water can contain, for example, a preservative described in JP-A-10-10754, an organic solvent described in JP-A-8-278636, and the like.

  The image-forming element thus developed is preferably washed with water, as described in JP-A-54-8002, JP-A-55-115045, JP-A-59-58431, and the like. It is post-treated with a desensitizing solution containing a rinsing solution containing a surfactant or the like, gum arabic or a starch derivative. These processes can be used in various combinations for the post-processing of the image forming element of the present invention.

  In consideration of environmental problems, development can be performed using so-called water having a neutral pH range. In this case as well, for the purpose of improving the developability, the surfactant described in the description of the developer and the above-described desensitizing solution for the purpose of desensitizing the plate surface after development can be added to water as a developing solution.

  The image forming element obtained by the above-described processing can be improved in rigidity resistance by a known post-exposure processing or heat treatment such as burning. Next, the image forming element obtained by the above processing is applied to an offset printer and used for printing a large number of sheets.

  The obtained image forming element is referred to as an on-machine development type. The image-forming element thus obtained can be used for a plate that can be attached to a printing press plate cylinder as it is after imagewise exposure and printing can be started.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to the range of these Examples.

[Preparation of photosensitive composition]
The composition of the photosensitive composition is as follows.

1: 80% by mass in 2-butanone obtained by reacting DESMODUR N100 (an aliphatic polyisocyanate resin based on hexamethylene diisocyanate, manufactured by Bayer) with hydroxyethyl acrylate and pentaerythritol triacrylate solution. (binder)
2: Sartomer SR-399 is dipentaerythritol pentaacrylate (manufactured by Sartomer). (Polymerizable compound)
3: Polymerizable phosphate monomer according to the present invention: 21% dispersion of acrylonitrile / polyethylene glycol methyl ether methacrylate / styrene copolymer in 80/20 mixture of n-propanol / water. (binder)
5: 75% solution (manufactured by Ciba Specialty Chemicals) of (4-methoxyphenyl [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate) in propylene carbonate. (Initiator)
6: Infrared absorber

7: 25% solution of modified dimethylpolysiloxane copolymer in xylene / methoxypropylacetic acid solution (byk Chemie (France)). (Surfactant)

[Neutralization treatment and coating solution preparation]
For the experiment numbers 1, 2, 3, 10, and 11 in Table 2 described later, the coating solution was prepared and neutralized by the following procedure.
The polymerizable monomer was added to the mixed solvent shown in Table 2 and stirred. The mixed solvent used at that time was selected in view of the solubility of the monomer. The pH of the solution after stirring was approximately 2.3. NaOH (or triethanolamine) 10% aqueous solution was added until the pH value before the phosphate ester monomer addition was shown. The molar amount of NaOH (or triethanolamine) required was almost the same as the molar amount of the phosphate ester monomer (0.289 g in terms of NaOH solids or 1.077 g in terms of 100% triethanolamine). After mixing this neutralized solution, the remaining coating solution components (urethane acrylate, Sartomer SR-399, graft copolymer, Irgacure 250, IR dye, Byk-336) were added and further stirred.

[Neutralization treatment and coating solution preparation]
The photosensitive composition solution shown in Table 1 was neutralized by the following procedure.
Phosmer PE was added to the mixed solvent and stirred to change the pH to approximately 2.3. Aqueous NaOH (or triethanolamine) solution was added until a pH value was shown in the absence of phosphate ester monomer. The amount of NaOH (or triethanolamine) required was almost the same as the molar amount of phosphate ester monomer (0.289 g for NaOH solids or 1.077 g for triethanolamine). After mixing this neutralized solution, other components were added and further stirred.

[Application]
Using a # 26 bar coater, the solution was applied onto a 0.24 mm thick support substrate substrate that had been anodized and silicate treated. After application, drying was performed in an oven at 100 degrees for 60 seconds. The coating weight at that time was 1.4 g / m ² .

[Evaluation of printing plate]
The coated support substrate was imaged at 222 mJ / cm ² using a CREO 3244 platesetter, and this plate was moistened with dampening water (1% NA-108W etchant from Dainippon Ink + 1% IPA aqueous solution), then ink (Dai Nippon Ink MKHS Red) was hand painted.
By performing ink printing, the photosensitive layer remained like an image in the portion cured at the time of exposure, and the uncured portion that was not exposed was developed to expose the grain of the support substrate. The adhesiveness of the photosensitive layer was evaluated by thoroughly rubbing the image forming area during the ink deposition. The adhesion of the photosensitive layer in the image forming area was evaluated in five grades A to E. When no damage is observed in the image forming area, it is determined that the adhesive property of the photosensitive layer is excellent (Evaluation A). When the image forming area is removed, it is determined that the adhesive property is poor (Evaluation E). did. In addition, the non-image area stain characteristics were evaluated in five grades A to E from the extent that ink remained in the non-image area. When the non-image area did not accept ink at all, it was determined that the non-image area stain characteristics were excellent (Evaluation A). When the non-image area received ink, it was determined that the non-image area stain characteristic was poor (Evaluation E). The printing plate was subjected to an aging acceleration test under the conditions of 38 ° C. and 80% humidity. After storing the plate under the above conditions, the non-image area stain property and the photosensitive layer adhesion after the aging acceleration test were evaluated in 5 stages of A to E using the plate after 5 days.

When the polymerizable phosphoric acid ester monomer of the photosensitive composition of Table 1 is changed variously, and the composition is neutralized by using an optimal mixed solvent for the monomer. The above-mentioned evaluation was performed on the plate of The results are shown in Table 2.

The monomer structure used in the above test but not yet shown is shown below.

From the results of Table 2, the phosphate ester monomers according to the present invention that are not neutralized and have a repeating structure of polyethylene oxide (—CH ₂ CH ₂ O—) (example numbers 5 and 8) and Those having no repetitive structure (example numbers 4, 6, 7, and 9) are clearly excellent in adhesion between the photosensitive layer support substrates and non-image area stains, which are characteristics required for printing plates. The result is obtained. Example No. 6 has a repeating structure of polyethylene oxide in the compound molecule, but having two acryloyl groups in the molecule increases the lipophilicity of the entire compound, making it easier to draw ink and making it non-image area stain-proof This is thought to have led to inferior results.
Of those using the phosphoric acid ester monomer according to the present invention, those neutralized with a base (Invention Examples 1-3, 10 and 11) were clearly evaluated after 3 days (HT 3 days) and 5 days (HT 5 days). (Comparison between Example 5 and Examples 1, 10, and 11). In particular, when attention is paid to examples using Invention PP (Invention Example 2 and Comparative Example 9), all properties are dramatically improved by neutralization. This proves that neutralizing phosphoric acid improves the effect, particularly the stability of the plate during storage.

It can be seen that having a repeating structure of an ethylene oxide group in the molecular structure of phosphoric acid methacrylate (PEG chain) has an obvious positive effect on adhesion to a grained substrate. (Comparison between Experimental Examples 10 and 12, Comparison between Experimental Examples 1 and 3)
In addition, in the case where the polymerizable monomer does not have a phosphate group or a neutralized phosphate group (Comparative Example 14), the substrate adhesion is completely inferior, and the composition may not be able to withstand printing that requires physical force. I understand.

[Printing test]
In order to confirm the functions of Invention Example 10, Invention Example 3, Comparative Example 13 and each composition component showing the most excellent characteristics, the graft polymer in Table 1 was removed, and the solid content% was urethane acrylate and sartomer. SR-399 and NaOH-neutralized Phosmer PE were allocated to each solid content% (Comparative Example 15), urethane acrylate, Sartomer SR-399 and monomers in Table 1 were removed, and the solid content% was allocated to the graft polymer. (Comparative Example 16), solid content% of monomer (NaOH-neutralized PhosmerPE) in Table 1 assigned to each solid content% of urethane acrylate, Sartomer SR-399, and NaOH-neutralized PhosmerPE (Comparative Example 17) The solid content% of the monomer (NaOH-neutralized Phosmer PE) in Table 1 was changed to 2%, and the difference solid content% was changed to urethane acrylate, Sartomer SR-399, NaOH. What was allocated to each solid content% of Japanese PhosmerPE (Comparative Example 18), the solid content% of the monomer (NaOH neutralized PhosmerPE) in Table 1 was 5%, and the solid content% of the difference was urethane acrylate and Sartomer SR -399, each of the NaOH-neutralized PhosmerPE was assigned to each solid content% (Invention Example 19), the solid content% of the monomer (NaOH-neutralized PhosmerPE) in Table 1 was 20%, and the difference solid content% was Urethane acrylate, Sartomer SR-399, NaOH-neutralized PhosmerPE, each of which was subtracted to the solid content% (Invention Example 20), and the solid content% of the monomer (NaOH-neutralized PhosmerPE) in Table 1 was 30%. The solid content% of the difference was subtracted to the solid content% of each of urethane acrylate, Sartomer SR-399, and NaOH neutralized Phosmer PE (Comparative Example 21), 4% of the solid content% of Irgacure 250 in Table 1 To A haloalkyl compound (Triazine-B manufactured by PCAS) (Invention Example 22), Irgacure 250 in Table 1 was changed to a borate compound (P3B manufactured by Showa Denko KK), and the IR dye was polymethine IR dye (Showa Denko) IRT) (Invention Example 23) was prepared and a printing test was conducted.

Using the above composition, a printing test was performed using an R-200 printer manufactured by Man Roland and an S-26 printer manufactured by Komori Corporation. The printing conditions are as follows.
Ink: DIC GEOS-G N grade printing paper: Oji Paper Co., Ltd. Royal coat 44.5kg / A
Dampening solution: DIC K-705 1% + IPA 10% aqueous solution (Komori)
DIC NA-108W 1% + IPA 1% aqueous solution (Roland)
Blanket: Kinyo Co., Ltd. S-7400
For on-press development, the product of the present invention was supplied with 10 rotations of water after the start of printing, then supplied with ink for 10 rotations, and then started printing. After supplying 10 revolutions of water after starting printing, when the ink is supplied and rotated 10 times, the photosensitive layer in the non-image area is completely removed. On-machine developability is possible. Those in which the layer remained were not allowed to be developed on the machine. The comparative version was printed by a conventional method. The printing durability test is an accelerated test with a higher printing pressure. The results are shown in Table 3.

  In Example 10, because of on-press development, ink is carried well and the number of damaged paper sheets is smaller than that of a normal PS plate. Also, there is no problem in printing suitability such as water width and blanket remaining. As for printing durability, it was under accelerated test conditions, but had printing durability equivalent to that of PN plates that have a proven track record in the market. Furthermore, it can be seen from the results of Invention Example 3 that the difference in adhesion shown in Table 2 also appears in the printing test. The non-image area stain characteristics of Comparative Example 13 appear as non-image area dirt in printability. From Comparative Examples 15 and 16, it was found that a binder resin and a polymerizable compound were indispensable for the photosensitive layer composition. From Comparative Examples 17, 18, and 21, and Inventive Examples 19, 20, and 10, it can be seen that the optimum weight% of the polymerizable phosphate monomer is 5 to 20% by weight. Further, it was found from Invention Examples 22 and 23 that a borate compound and a trihaloalkyl-substituted compound are useful as a polymerization initiator.

The structure of the compound used in the printing test is shown below.

Claims (6)

An image forming element having a substrate and a photosensitive layer made of a photosensitive composition provided on the surface of the substrate,
The photosensitive composition comprises a neutralized phosphate ester compound having a (meth) acryloyl group ,
The ratio of the neutralized phosphate ester compound is 5 to 20% by mass of the photosensitive composition.
Imaging elements, wherein the this. The neutralized phosphate ester compound has the following formula:

( Wherein R ₁ is a hydrogen atom or a methyl group,
R ₂ is a hydrogen atom or a methyl group
n is 1 to 6, and
X is a counter ion)
The imaging element according to claim 1, which is selected from the compounds represented by: R in the above formula ₂ The imaging element according to claim 2, wherein is a hydrogen atom. The image forming element according to any one of claims 1 to 3, wherein the photosensitive composition contains a compound selected from an onium salt compound, a boron salt compound, and a trihaloalkyl-substituted compound as a polymerization initiator. The photosensitive composition contains (a) an infrared absorber, (b) a polymerization initiator, (c) a polymerizable compound, and (d) a binder resin. The imaging element according to item 1. The image forming element according to any one of claims 1 to 5 is image-exposed with an infrared laser, and then a non-image part is removed on a printing machine using a fountain solution and / or printing ink. An image forming method.