JP4912934B2 - Photosensitive composition, image recording material, and image recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive composition with a new photopolymerization initiation system for an image recording material such as a lithographic printing plate for scanning exposure excellent in work efficiency and economical efficiency, suitable for a CTP system and having high sensitivity to an oscillation wavelength of an inexpensive short-wavelength semiconductor laser and high storage stability. <P>SOLUTION: The photosensitive composition comprises (A) a hexaarylbiimidazole type compound having a structure represented by general formula (I), (B) a sensitizing dye having an absorption maximum &lambda;<SB>max</SB>at 350-850 nm, and (C) an addition polymerizable compound having an ethylenically unsaturated double bond. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention is a photosensitive composition that can be used for image forming materials such as three-dimensional stereolithography, holography, planographic printing plates, color proofs, photoresists and color filters, and photocurable resin materials such as inks, paints, and adhesives. And an image recording method using the same. In particular, a photosensitive composition that can be directly made using various lasers from a digital signal of a computer or the like, so-called lithographic printing plate material that can be directly made, or a photocurable ink, and an image recording method using the same About.

  Solid-state lasers, semiconductor lasers, and gas lasers that emit ultraviolet light, visible light, and infrared light having a wavelength of 300 nm to 1200 nm are easily available as high-power and small-sized lasers. It is very useful as a recording light source when making a plate directly from data. Various researches have been made on recording materials sensitive to these various laser beams. As typical examples, various positive recording materials (for example, patent documents) can be used as materials that can be recorded with an infrared laser having a photosensitive wavelength of 760 nm or more. 1), acid-catalyst-crosslinked negative recording materials (see, for example, Patent Document 2) and the like, and as a recording material compatible with 300 nm to 700 nm ultraviolet light or visible light laser, a radical polymerization negative recording material is used. (For example, see Patent Literature 3 and Patent Literature 4) and many others are known.

The problem common to all these image forming materials is how to enlarge the ON / OFF of the image in the above-mentioned various energy irradiated portions and unexposed portions, that is, the high sensitivity and storage stability of the image forming materials. It is compatible. Usually, the radical photopolymerization system is highly sensitive, but the sensitivity is greatly lowered due to polymerization inhibition by oxygen in the air. Therefore, means for providing an oxygen barrier layer on the image forming layer is taken. However, when an oxygen-blocking layer is provided, fogging due to dark polymerization or the like occurs, and storage stability deteriorates. Accordingly, it is difficult to achieve both high sensitivity and storage stability. The conventional technique has not obtained a satisfactory result, and a new technique that has not been conventionally required has been demanded.
On the other hand, high-sensitivity photoinitiators are described in Non-Patent Document 1 and Non-Patent Document 2, and are known.
Specific hexaarylbiimidazole type compounds are described in Patent Document 5 and Non-Patent Document 3.

U.S. Pat. No. 4,708,925 JP-A-8-276558 U.S. Pat. No. 2,850,445 Japanese Patent Publication No. 44-20189 JP 60-264279 A Bruce M. By Monroe et al., Chemical Rev. , 93, 435 (1993) R. S. By Davidson et al., Journal of Photochemistry and biology, 73, 81 (1993). J. et al. Chem. Soc. Perkin. Trans. 2361 (1975)

  An object of the present invention is to provide a photosensitive composition used as an image recording material for scanning exposure which is excellent in workability and economy and is suitable for a graphic system, and has a high wavelength with respect to an oscillation wavelength of an inexpensive shortwave semiconductor laser. The object is to provide a photosensitive composition for use as a sensitive image recording material. Another object of the present invention is to provide a photosensitive composition using a novel photopolymerization initiation system which is highly sensitive to a wide wavelength range from 350 nm to 850 nm and has high workability under yellow light. Still another object of the present invention is to provide an image recording material and an image recording method using the photosensitive composition.

  Accordingly, an object of the present invention is to provide a highly sensitive photosensitive composition which is excellent in workability and economy and is used as an image recording material for scanning exposure suitable for a graphic system. In particular, it is to provide a photosensitive composition that can be cured by direct exposure from digital data of a computer or the like by recording using solid-state laser and semiconductor laser light emitting ultraviolet light, visible light, and infrared light.

  As a result of intensive studies to achieve the above object, the present inventors have found that when a sensitizing dye and a hexaarylbiimidazole type compound having a specific structure are combined, a photopolymerization initiation system with very excellent sensitivity is obtained. The present inventors have found that a photopolymerization initiation system suitable for exposure at 350 nm to 850 nm, particularly 350 nm to 450 nm can be obtained. Furthermore, an image recording material using a photosensitive composition comprising this photopolymerization initiation system and an addition polymerizable compound that reacts with a radical or an acid, specifically, an addition polymerizable compound having an ethylenically unsaturated double bond. Thus, the inventors have found that a photosensitive composition having sufficient sensitivity to the oscillation wavelength of a short-wave semiconductor laser and that can be handled even under a bright safelight can be obtained, and the present invention has been achieved.

（一般式（Ｉ）中、Ｒ₁〜Ｒ₃、Ｒ₅〜Ｒ₇は、それぞれ独立に、一価の非金属原子団を表し、Ｒ₄、Ｒ₈はそれぞれ独立に二価の非金属原子団を表す。ｌ、ｍ、ｎはそれぞれ独立に０〜５の整数であり、ｎ＝０ではＲ₄、Ｒ₈はそれぞれ単結合となる。またＲ₁〜Ｒ₃、Ｒ₅〜Ｒ₇はそれぞれ独立に、互いに結合して、脂肪族性または芳香族性の環を形成することができる。）
（２）増感色素（Ｂ）が、クマリン類、スチリル類、シアニン類、及びメロシアニン類からなる群より選ばれる色素であることを特徴とする、上記（１）記載の感光性組成物。
（３）支持体上に、上記（１）または（２）記載の感光性組成物を含有する感光層を有する画像記録材料。
（４）支持体上に、上記（１）または（２）記載の感光性組成物を含有する感光層を有する画像記録材料に対し、４５０ｎｍより短波長のレーザ光源を用いて走査露光を行う画像記録方法。
（５）更に、未露光部を水系現像溶液にて除去することを特徴とする、上記（４）に記載の画像記録方法。
（６）支持体上に、上記（１）または（２）記載の感光性組成物を含有する感光層を有する平版印刷版原版。 That is, the present invention is as follows.
(1) (A) a hexaarylbiimidazole type compound having a structure represented by the following general formula (I) (B) a sensitizing dye having an absorption maximum λ _max at 350 nm to 850 nm, and (C) ethylenic unsaturation An addition polymerizable compound having a double bond,
Containing the photosensitive composition.
Formula (I)

(In the general formula (I), R _{1 to} R ₃ and R _{5 to} R ₇ each independently represents a monovalent nonmetallic atomic group, and R ₄ and R ₈ each independently represents a divalent nonmetallic atom. L, m and n are each independently an integer of 0 to 5, and when n = 0, R ₄ and R ₈ are each a single bond, and R _{1 to} R ₃ and R _{5 to} R ₇ are Each independently can be bonded to each other to form an aliphatic or aromatic ring.)
(2) The photosensitive composition as described in (1) above, wherein the sensitizing dye (B) is a dye selected from the group consisting of coumarins, styryls, cyanines, and merocyanines.
(3) An image recording material having a photosensitive layer containing the photosensitive composition according to (1) or (2) above on a support.
(4) An image obtained by subjecting an image recording material having a photosensitive layer containing the photosensitive composition described in (1) or (2) above to a support, by scanning exposure using a laser light source having a wavelength shorter than 450 nm. Recording method.
(5) The image recording method according to (4), further comprising removing an unexposed portion with an aqueous developer solution.
(6) A lithographic printing plate precursor having a photosensitive layer containing the photosensitive composition according to (1) or (2) above on a support.

The photosensitive composition of the present invention is a hexaarylbiimidazole type compound characterized by having a structure in which aromatic rings at positions 4 and 5 in the imidazole structure part are linked by a substituent R ₄ or R ₈ ( An initiator), a sensitizing dye, and an addition polymerizable compound that reacts with at least one of a radical and an acid.
The photosensitive composition of the present invention is characterized by having very excellent sensitivity. The reason for this is that a hexaarylbiimidazole type compound characterized by having a structure in which the aromatic rings at positions 4 and 5 in the imidazole structure part are connected by a substituent R ₄ or R ₈ is substituted as described above. The compound having no structure connected by the groups R ₄ and R ₈ has a higher planarity between two aromatic rings, so that the electron conjugation property becomes stronger. As a result, it is presumed that the active radical generated after the compound is excited by light can be stabilized. That is, this is considered to indicate that the recombination process between the active radical pairs is suppressed, and that many of the active radicals can contribute to the polymerization, and is considered to exhibit high sensitivity.

According to the present invention, a photosensitive composition having high sensitivity and excellent storage characteristics can be obtained.
The photosensitive composition of the present invention can also provide an image forming material having high sensitivity suitable for scanning exposure by a semiconductor laser having a short wavelength and excellent workability and economy.

Hereinafter, embodiments of the present invention will be described in detail.
The photosensitive composition of this invention contains the following.
(A) A hexaarylbiimidazole type compound having a structure represented by the general formula (I).
(B) A sensitizing dye having an absorption maximum λ _max at 350 nm to 850 nm.
(C) An addition polymerizable compound having an ethylenically unsaturated double bond.
Among the above compositions, (A) a hexaarylbiimidazole type compound characterized by having a structure represented by the general formula (I) serves as a photopolymerization initiator. (A) A hexaarylbiimidazole type compound and (B) a sensitizing dye having an absorption maximum λ _max at 350 nm to 850 nm may be referred to as a photopolymerization initiation system in this specification. Further, when a co-sensitizer is used, it may be called a photopolymerization initiation system including a co-sensitizer in the above components.

<(A) Hexaarylbiimidazole type compound (initiator)>
In the hexaarylbiimidazole type compound constituting the photopolymerization initiation system used in the photosensitive composition of the present invention, the aromatic rings at the 4th and 5th positions in the imidazole structure are linked by substituents R ₄ and R ₈ . It is a hexaarylbiimidazole type compound represented by the following general formula (I), characterized by having a structure.

一般式（Ｉ）中、Ｒ₁〜Ｒ₃、Ｒ₅〜Ｒ₇は、それぞれ独立に、一価の非金属原子団を表し、Ｒ₄、Ｒ₈はそれぞれ独立に二価の非金属原子団を表す。ｌ、ｍ、ｎはそれぞれ独立に０〜５の整数であり、ｎ＝０ではＲ₄、Ｒ₈はそれぞれ単結合となる。またＲ₁〜Ｒ₃、Ｒ₅〜Ｒ₇はそれぞれ独立に、互いに結合して、脂肪族性または芳香族性の環を形成することができる。 Formula (I)

In general formula (I), R _{1 to} R ₃ and R _{5 to} R ₇ each independently represents a monovalent nonmetallic atomic group, and R ₄ and R ₈ each independently represent a divalent nonmetallic atomic group. Represents. l, m, and n are each independently an integer of 0 to 5, and when n = 0, R ₄ and R ₈ are each a single bond. R _{1 to} R ₃ and R _{5 to} R ₇ can be independently bonded to each other to form an aliphatic or aromatic ring.

The definition of each group in general formula (I) is demonstrated in detail below.
R ₁ , R ₂ , R ₃ , R ₅ , R ₆ and R ₇ are each independently a monovalent nonmetallic atomic group.
In the present specification, “non-metallic atomic group” refers to a group consisting of an atomic group other than a metal atom (for example, a hydrogen atom, a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or a combination thereof). means.
The monovalent nonmetallic atomic group representing R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ is preferably (i) a substituted or unsubstituted alkyl group, (ii) a substituted or unsubstituted group An alkenyl group, (iii) a substituted or unsubstituted aryl group, (iv) a substituted or unsubstituted heteroaryl group, (v) a substituted or unsubstituted amino group, (vi) a substituted or unsubstituted alkoxy group, (vii And a substituted or unsubstituted alkylthio group, (viii) a hydroxy group, (ix) a cyano group, (x) an alkoxycarbonyl group, (xi) an amide group, (xii) an acyl group, and (xiii) a halogen atom.

R ₄ and R ₈ are each independently a divalent nonmetallic atomic group, and when n = 0, R ₄ and R ₈ are a single bond. Specific examples of R ₄ and R ₈ include —C (═S) —, —S—, —S (═O) —, —S (═O) ₂ —, —O—, —N (═R ₉ ). -(R _{9 has} the same definition as R ₁ ), -CH _2- , -C (= O)-, -CH ₂ = CH _2- , -CF _2- , -C (CH ₃ ) _2- More preferred are single bonds, —O—, and —S—, and most preferred are single bonds.

Next, more preferable examples of R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R ₉ will be specifically described.
(i) Examples of preferable alkyl groups as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , and R ₉ are linear, branched, and cyclic having 1 to 20 carbon atoms Specific examples thereof include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group. , Tridecyl group, hexadecyl group, octadecyl group, eicosyl group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2- A methylhexyl group, a cyclohexyl group, a cyclopentyl group, and a 2-norbornyl group can be exemplified. Among these, linear alkyl groups having 1 to 12 carbon atoms, branched alkyl groups having 3 to 12 carbon atoms, and cyclic alkyl groups having 5 to 10 carbon atoms are more preferable.

(ii) Examples of preferable alkenyl groups as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ and R ₉ include at least one double bond derived from the above alkyl group having 2 or more carbon atoms. A group having

  As the substituent of the substituted alkyl, alkenyl, alkoxy, amino, amide, alkylthio, alkoxycarbonyl group, a monovalent non-metallic atomic group other than hydrogen is used. Preferred examples include halogen atoms (-F, -Br, -Cl, -I), hydroxyl group, alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkyl Carbamoyloxy group, N, N-diarylcarbamoyloxy Group, N- alkyl -N- arylcarbamoyloxy group, alkylsulfoxy group,

Arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-arylureido Group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′- Alkyl-N-arylureido group, N ', N'-dialkyl-N-alkylureido group, N', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N'- Aryl-N-arylureido group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl-N-ary Ruureido group, N'- alkyl -N'- aryl -N- alkylureido group, N'- alkyl -N'- aryl -N- arylureido group,

Alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N -Aryloxycarbonylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group,

Alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (—SO ₃ H) and its conjugate base group (hereinafter referred to as sulfonate group), alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group,

Phosphono group (—PO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as “phosphonate group”), dialkyl phosphono group (—PO ₃ (alkyl) ₂ ), diaryl phosphono group (—PO ₃ (aryl) ₂ ) , Alkylaryl phosphono group (—PO ₃ (alkyl) (aryl)), monoalkyl phosphono group (—PO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkyl phosphonate group), monoaryl Phosphono group (—PO ₃ H (aryl)) and its conjugate base group (hereinafter referred to as aryl phosphonate group), phosphonooxy group (—OPO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonateoxy) referred to as group), dialkyl phosphonooxy group _{(-OPO 3 (alkyl) 2)} , diaryl phosphonooxy group (-OPO ₃ (ary ) _2), alkylaryl phosphonooxy group (-OPO ₃ (alkyl) (aryl)), monoalkyl phosphonooxy group (-OPO ₃ H (alkyl)) and its conjugated base group (hereinafter, alkyl phosphonophenyl group Monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base group (hereinafter referred to as arylphosphonateoxy group), cyano group, nitro group, aryl group, heteroaryl group, alkenyl Group, alkynyl group and the like.

  Specific examples of the alkyl group in these substituents include the above-described alkyl groups, and specific examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a tolyl group, a xylyl group, a mesityl group, and a cumenyl group. , Chlorophenyl group, bromophenyl group, chloromethylphenyl group, hydroxyphenyl group, methoxyphenyl group, ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylamino Phenyl group, dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group, ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, cyanophene Group, sulfophenyl group, sulfonatophenyl group, phosphonophenyl phenyl group, and a phosphonophenyl phenyl group.

  As the heteroaryl group which may be substituted with these substituents, a monocyclic or polycyclic aromatic ring containing at least one of nitrogen, oxygen and sulfur atoms is used, and examples of particularly preferred heteroaryl groups include For example, thiophene, thiathrene, furan, pyran, isobenzofuran, chromene, xanthene, pyrrole, pyrazole, isothiazole, isoxazole, pyrazine, pyrimidine, pyridazine, indolizine, isoindolizine, indoyl, indazole, purine, quinolidine, Examples include isoquinoline, phthalazine, naphthyridine, quinazoline, cinolin, pteridine, carbazole, carboline, phenanthrine, perimidine, phenanthroline, phthalazine, phenalazine, and furazane, and these may be further benzo-condensed. Or it may have a substituent.

  Examples of the alkenyl group that may be substituted with these substituents include vinyl group, 1-propenyl group, 1-butenyl group, cinnamyl group, 2-chloro-1-ethenyl group, and the like, and alkynyl group Examples of these include ethynyl group, 1-propynyl group, 1-butynyl group, trimethylsilylethynyl group and the like.

Examples of G1 in the acyl group (G1CO-) as these substituents include hydrogen, and the above alkyl groups and aryl groups.
Among these substituents, even more preferred are halogen atoms (—F, —Br, —Cl, —I), alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, N-alkylamino groups, N, N— Dialkylamino group, acyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, acylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, sulfo group, sulfonate group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group Group, N-arylsulfa Yl group, N-alkyl-N-arylsulfamoyl group, phosphono group, phosphonate group, dialkyl phosphono group, diaryl phosphono group, monoalkyl phosphono group, alkyl phosphonate group, monoaryl phosphono group, aryl phosphine group Examples include an onato group, a phosphonooxy group, a phosphonateoxy group, an aryl group, and an alkenyl group.

  On the other hand, examples of the alkylene group in the substituted alkyl group include divalent organic residues obtained by removing any one of the hydrogen atoms on the alkyl group having 1 to 20 carbon atoms. Can include linear alkylene groups having 1 to 12 carbon atoms, branched chains having 3 to 12 carbon atoms, and cyclic alkylene groups having 5 to 10 carbon atoms.

The substituent of the substituted alkyl group that is preferable as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , and R ₉ obtained by combining the substituent and the alkylene group is optional, but is preferably substituted. Specific examples of the alkyl group include chloromethyl, bromomethyl, 2-chloroethyl, trifluoromethyl, methoxymethyl, methoxyethoxyethyl, allyloxymethyl, phenoxymethyl, methylthiomethyl, and tolylthiomethyl. Group, ethylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group,

N-cyclohexylcarbamoyloxyethyl group, N-phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl group, 2-oxoethyl group, 2-oxopropyl group, carboxypropyl group, methoxycarbonylethyl group, allyl Oxycarbonylbutyl group, chlorophenoxycarbonylmethyl group, carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-dipropylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, N-methyl-N- (sulfo) Phenyl) carbamoylmethyl group, sulfobutyl group, sulfonatobutyl group, sulfamoylbutyl group, N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfamoyl group Propyl group,

N-methyl-N- (phosphonophenyl) sulfamoyloctyl group, phosphonobutyl group, phosphonatohexyl group, diethylphosphonobutyl group, diphenylphosphonopropyl group, methylphosphonobutyl group, methylphosphonatobutyl group , Tolylphosphonohexyl group, tolylphosphonatohexyl group, phosphonooxypropyl group, phosphonateoxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, p-methyl Benzyl group, cinnamyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group, etc. be able to.

(iii) Specific examples of preferred aryl groups as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , and R ₉ include those in which 1 to 3 benzene rings form a condensed ring, benzene A ring and a 5-membered unsaturated ring form a condensed ring.

Specific examples include phenyl group, biphenyl group, naphthyl group, tolyl group, xylyl group, mesityl group, cumenyl group, chlorophenyl group, bromophenyl group, chloromethylphenyl group, hydroxyphenyl group, methoxyphenyl group. , Ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylaminophenyl group, dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl Group, ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, cyanophenyl group, sulfophenyl group, sulphonatophenyl group, phosphonophenyl group, phosphine group Natofeniru group can be exemplified, which may have a substituent.
More preferable examples include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, and a fluorenyl group, and among these, a phenyl group and a naphthyl group are more preferable.

(iv) Preferred heteroaryl groups for R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₉ are monocyclic or polycyclic containing at least one of nitrogen, oxygen, and sulfur atoms Examples of particularly preferred heteroaryl groups in which aromatic rings are used include, for example, thiophene, thiathrene, furan, pyran, isobenzofuran, chromene, xanthene, pyrrole, pyrazole, isothiazole, isoxazole, pyrazine, pyrimidine, pyridazine, Indolizine, isoindolizine, indoir, indazole, purine, quinolidine, isoquinoline, phthalazine, naphthyridine, quinazoline, cinolin, pteridine, carbazole, carboline, phenanthrine, acridine, perimidine, phenanthroline, phthalazine, phenazadine, furazane, etc. Is, it further may be benzo-fused or may have a substituent.

  As the substituent of the substituted aryl or heteroaryl group, a monovalent nonmetallic atomic group excluding hydrogen is used. Preferred examples include halogen atoms (—F, —Br, —Cl, —I), hydroxyl groups. , Alkoxy group, aryloxy group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N -Diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N-diaryl Carbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, a Kirusuruhokishi group,

Arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-arylureido Group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′- Alkyl-N-arylureido group, N ', N'-dialkyl-N-alkylureido group, N', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N'- Aryl-N-arylureido group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl-N-ary Ruureido group, N'- alkyl -N'- aryl -N- alkylureido group, N'- alkyl -N'- aryl -N- arylureido group,

Alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N -Aryloxycarbonylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group,

Alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (—SO ₃ H) and its conjugate base group (hereinafter referred to as sulfonate group), alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group,

Phosphono group (—PO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as “phosphonate group”), dialkyl phosphono group (—PO ₃ (alkyl) ₂ ), diaryl phosphono group (—PO ₃ (aryl) ₂ ) , Alkylaryl phosphono group (—PO ₃ (alkyl) (aryl)), monoalkyl phosphono group (—PO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkyl phosphonate group), monoaryl Phosphono group (—PO ₃ H (aryl)) and its conjugate base group (hereinafter referred to as aryl phosphonate group), phosphonooxy group (—OPO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonateoxy) referred to as group), dialkyl phosphonooxy group _{(-OPO 3 (alkyl) 2)} , diaryl phosphonooxy group (-OPO ₃ (ary ) _2), alkylaryl phosphonooxy group (-OPO ₃ (alkyl) (aryl)), monoalkyl phosphonooxy group (-OPO ₃ H (alkyl)) and its conjugated base group (hereinafter, alkyl phosphonophenyl group Monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base group (hereinafter referred to as arylphosphonateoxy group), cyano group, nitro group, aryl group, heteroaryl group, alkenyl Group, alkynyl group and the like.

Preferred examples of the substituted or unsubstituted amino group as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₉ include C1-C10 monoalkylamino and C1-C10 dialkylamino, More preferred are dimethylamino and diethylamino groups.
Preferred (vi) substituted or unsubstituted alkoxy group as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₉ is a group in which an oxygen atom is bonded to the above-mentioned (i) alkyl group. . The substituents are also as described above.
Preferred (vii) substituted or unsubstituted alkylthio group as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₉ is a group in which a sulfur atom is bonded to the above-mentioned (i) alkyl group. . The substituents are also as described above.
A preferable (x) alkoxycarbonyl group as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₉ is a group in which a carbonyl is bonded to the above alkoxy group.
Preferred (xii) acyl groups as R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₉ include C1-C10 alkyl ketones, aryl ketones, and heteroaryl ketones. Aryl and heteroaryl groups are based on the foregoing. More preferred are an acetyl group and a benzoyl group.

In addition, R _{1 to} R ₃ and R _{5 to} R ₇ may be bonded to each other, and as an aliphatic or aromatic ring, for example, adjacent R ₁ may be bonded to each other as shown below. A cyclohexane ring or a benzene ring may be formed. Preferred examples include aliphatic or aromatic rings having 3 to 8 carbon atoms, and more preferred are cycloheptane and cyclohexane rings.

（II） （III） Furthermore, the hexaarylbiimidazole compound is more preferably a structure represented by the following general formulas (II) and (III).

(II) (III)

In general formulas (II) and (III), R _{1 to} R ₃ and R _{5 to} R ₇ are the same as defined in general formula (I). m is an integer of 0-3 each independently. X ₁ and X ₂ are each independently at least one substituent selected from the group consisting of a halogen atom, a cyano group, an alkoxycarbonyl group, a fluorine-substituted alkyl group, and an acyl group. The definition of each said group is the same as that of R < ₁ > -R < ₃ >, R < ₅ > -R < ₇ > of general formula (I).
Y ₁ and Y ₂ are —O—, —SO—, —SO ₂ —, —NR ₉ —, —CR ₁₀ R ₁₁ —, and —S—. Definition of R ₉ to R ₁₁ are the same as R ₁ to R _8.
R _{1 to} R ₃ and R _{5 to} R ₇ can be independently bonded to each other to form an aliphatic or aromatic ring.

In addition, the said compound has the tendency for a solvent solubility to fall because the molecular packing property increases by cyclic structure formation. In order to suppress this, it is preferable to introduce a bulky substituent in any of R _{1 to} R ₃ and R _{5 to} R ₇ and introduce a solvent solubility-imparting group while suppressing molecular packing properties. An alkoxy group, an alkoxycarbonyl group, and a substituted alkyl group are preferable, and an alkoxy group having 4 or more carbon atoms is more preferable.
Further, although different from the above estimation, it has been found that introduction of a fluorine atom at the para-position of the 4- or 5-position aryl group is also useful for imparting solvent solubility, but the cause is unknown. Therefore, it can be said that a halogen atom, particularly a fluorine atom is also useful as a preferred substituent.

Next, the following exemplary compounds (T-1) to (T-21) are shown as hexaarylbiimidazole type compounds having a preferred structure, but the present invention is not limited to these.

Here, a typical synthesis example of the hexaarylbiimidazole type compound described above will be shown.
Synthesis of [Exemplary Compound (T-4)] <Working Step>
After mixing 3.7 g of potassium ferricyanide, 3.1 g of potassium hydroxide, 70 ml of water and 40 ml of toluene, the mixture was stirred at room temperature until there was no solid. Thereafter, 2.8 g of T′-4 (the following compound) was added, heated to 80 ° C. in an oil bath, and stirred for 4 hours under reflux.

The reaction solution stirred for 4 hours under reflux was allowed to cool, 100 ml of water was added, and the mixture was extracted with toluene. The organic phase consisting of toluene was washed with aqueous sodium chloride solution and then with water. After washing, the organic phase was concentrated to give a red light oil. The obtained liquid was recrystallized with IPA to obtain 2.5 g of the target T-4.
Other hexaarylbiimidazole type compounds can be synthesized in the same manner by appropriately selecting starting materials, compounds to be added, and the like.

  The photosensitive composition of the present invention preferably contains the aforementioned hexaarylbiimidazole type compound in the range of 0.5 to 20% by mass in the total solid content constituting the composition. More preferably, it is 1-10 mass%. The sensitivity can be increased by increasing the amount, but if the amount is increased too much, the non-polymerizable solid content increases and the film hardness after polymerization decreases, so that the concentration range is preferable.

  In the present invention, in addition to the specific hexaarylbiimidazole type compound, other known photopolymerization initiators, thermal polymerization initiators and the like can be selected and used in combination as long as the effects of the present invention are not impaired. . Examples of these polymerization initiators that can be used in combination include known onium salts having no carboxylic acid structure in the counter cation moiety, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, and quinonediazides. Etc.

  Specific examples of the onium salt that can be suitably used as a radical generator that can be used in combination include those described in paragraphs [0030] to [0033] of JP-A No. 2001-133969.

When other polymerization initiators are used in combination, the content thereof is preferably 50% by mass or less of the hexaarylbiimidazole represented by the general formula (I).
The radical generator used in the present invention preferably has a maximum absorption wavelength of 500 nm or less, more preferably 400 nm or less.

<(B) Sensitizing dye>
The sensitizing dye used in the photosensitive composition of the present invention has an absorption maximum λmax at 350 to 850 nm. More preferably, one having an absorption maximum λmax at 350 to 450 nm can be mentioned.
Such sensitizing dyes include polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine). Oxacarbocyanine), merocyanines (eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, Anthraquinone), squaliums (for example, squalium), coumarins (for example, diethylaminocoumarin), and styryls (for example, distyrylbenzene or the following aminostyryl compounds). .

より好ましい増感色素としては、クマリン類、スチリル類、シアニン類、及びメロシアニン類からなる群より選ばれる色素が挙げられる。更に好ましくはアミノスチリル類が挙げられる。

More preferable sensitizing dyes include dyes selected from the group consisting of coumarins, styryls, cyanines, and merocyanines. More preferred are aminostyryls.

  More preferable examples of the sensitizing dye include compounds represented by the following general formulas (IV) to (VII).

In the general formula (IV), A ₁ represents a sulfur atom or NR ⁶ , R ⁶ represents an alkyl group or an aryl group, and L ₂ represents a basic nucleus of the dye in combination with the adjacent A ₁ and the adjacent carbon atom. Represents a nonmetallic atomic group to be formed, R ⁷ and R ⁸ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁷ and R ⁸ are bonded to each other to form an acidic nucleus of the dye. Also good. W represents an oxygen atom or a sulfur atom.
As described in the general formula (I), in this specification, “non-metallic atomic group” means an atomic group other than a metal atom (for example, a hydrogen atom, a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, etc. Or a combination thereof.
In the general formula (IV), preferred examples of the “monovalent nonmetallic atomic group” in the definition of R ⁷ and R ⁸ are a carbon atom, an oxygen atom, a nitrogen atom, and a sulfur atom.

上記式中、Ｒ¹、Ｒ²はそれぞれ独立に、炭素数１〜１０のアルキル基、炭素数１〜１０のアルコキシ基、ハロゲン原子から選択され、Ｘ、Ｙはそれぞれ独立に、硫黄原子、ＮＲ³（Ｒ³は炭素数１〜１０のアルキル基）、ＣＲ⁴Ｒ⁵（Ｒ⁴、Ｒ⁵はそれぞれ独立に炭素数１〜１０のアルキル基を表す）、酸素原子を表す。
Ｒ⁷、Ｒ⁸が互いに結合して形成する“色素の酸性核”とは、下記構造を表す。 In the general formula (IV), preferred examples of the non-metallic atomic group forming the basic nucleus of the dye formed by L ₂ , A ₁ and the adjacent carbon atom together are groups represented by the following structural formula.

In the above formula, R ¹ and R ² are each independently selected from an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a halogen atom, and X and Y are each independently a sulfur atom, NR ³ (R ³ is an alkyl group having 1 to 10 carbon atoms), CR ⁴ R ⁵ (R ⁴ and R ⁵ each independently represents an alkyl group having 1 to 10 carbon atoms), and an oxygen atom.
The “acidic nucleus of the dye” formed by combining R ⁷ and R ⁸ with each other has the following structure.

以下に一般式（ＩＶ）で表される化合物の好ましい具体例を示す。

The preferable specific example of a compound represented by general formula (IV) below is shown.

In the general formula (V), A ₂ represents a sulfur atom or NR ¹⁵ , L ₄ represents a nonmetallic atomic group that forms a basic nucleus of the dye in combination with adjacent A ₂ and a carbon atom, R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represent a monovalent non-metallic atomic group, and R ¹⁵ represents an alkyl group or an aryl group.
The “monovalent nonmetallic atomic group” and the “nonmetallic atomic group forming the basic nucleus of the dye” in the general formula (V) have the same definitions as in the general formula (IV).
Preferable examples of the compound represented by the general formula (V) include the following.

In general formula (VI), A ₃ and A ₄ each independently represent —S— or —NR ¹⁸ —, and R ¹⁸ each independently represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. , L ₅ and L ₆ each independently represents a nonmetallic atomic group which forms a basic nucleus of a dye in cooperation with adjacent A ₃ , A ₄ and adjacent carbon atoms, and R ¹⁶ and R ¹⁷ each independently They can be monovalent non-metallic atomic groups or bonded to each other to form an aliphatic or aromatic ring.
The “monovalent nonmetallic atomic group” and the “nonmetallic atomic group forming the basic nucleus of the dye” in the general formula (VI) have the same definitions as in the general formula (IV).
Preferable examples of the compound represented by the general formula (VI) include the following.

In General Formula (VII), Ar ¹ represents an aromatic ring or a hetero ring that may have a substituent, and A ₅ represents an oxygen atom, a sulfur atom, or —NR ²³ —. R ²¹ , R ²² and R ²³ each independently represents a hydrogen atom or a monovalent nonmetallic atomic group, and R ²⁴ and R ²¹ , and R ²² and R ²³ each represent an aliphatic or aromatic ring. Can be combined to form)
The “monovalent nonmetallic atomic group” in general formula (VII) has the same definition as in general formula (IV).
Ar ^{1 in the} general formula (VII) includes an aryl group which may have a substituent, and the substituent is particularly preferably an alkyl, alkoxy, or dialkylamino group.
Preferable specific examples of the compound represented by the general formula (VII) include those shown below.

  Regarding the sensitizing dye in the present invention, when it is used as a lithographic printing plate precursor, various chemical modifications for improving the characteristics of the photosensitive layer can be performed. For example, by combining a sensitizing dye and an addition polymerizable compound structure (for example, an acryloyl group or a methacryloyl group) by a method such as a covalent bond, an ionic bond, or a hydrogen bond, the exposure film can be increased in strength or exposed. Unnecessary precipitation suppression of the dye from the subsequent film can be performed.

  Further, when the photosensitive composition of the present invention is used as a lithographic printing plate precursor, it is a preferred use mode of the photosensitive layer, which is hydrophilic for the purpose of improving the processability to an (alkali) aqueous developer. It is effective to introduce a functional moiety (carboxyl group and its ester, sulfonic acid group and its ester, ethylene oxide group or other acid group or polar group). In particular, ester-type hydrophilic groups have a relatively hydrophobic structure in the photosensitive layer, so that they have excellent compatibility, and in the developer, acid groups are generated by hydrolysis to increase hydrophilicity. Have In addition, for example, a substituent can be appropriately introduced in order to improve the compatibility in the photosensitive layer and to suppress crystal precipitation. For example, in certain types of photosensitive systems, unsaturated bonds such as aryl groups and allyl groups may be very effective in improving compatibility. By introducing an obstacle, crystal precipitation can be remarkably suppressed. In addition, by introducing a phosphonic acid group, an epoxy group, a trialkoxysilyl group, or the like, adhesion to an inorganic substance such as a metal or a metal oxide can be improved. In addition, a method such as polymerization of a sensitizing dye can be used depending on the purpose.

Details of the usage such as which structure of these sensitizing dyes are used, whether they are used alone or in combination of two or more, and how much is added, can be appropriately set according to the performance design of the final photosensitive material. .
For example, the compatibility with the photosensitive composition layer can be enhanced by using two or more sensitizing dyes in combination. In selecting the sensitizing dye, in addition to the photosensitivity, the molar extinction coefficient at the emission wavelength of the light source used is an important factor. By using a dye having a large molar extinction coefficient, the amount of the dye added can be made relatively small, which is economical and advantageous from the viewpoint of film physical properties of the photosensitive layer when used in a lithographic printing plate precursor. It is. The photosensitivity of the photosensitive layer, the resolution, and the physical properties of the exposed film are greatly affected by the absorbance at the light source wavelength. Therefore, the addition amount of the sensitizing dye is appropriately selected in consideration of these.

  However, for example, for the purpose of curing a thick film having a thickness of 5 μm or more, the degree of curing may be increased by lower absorbance. When used as a lithographic printing plate used in a relatively thin film thickness, the amount of sensitizing dye added is such that the absorbance of the photosensitive layer is in the range of 0.1 to 1.5, preferably in the range of 0.25 to 1. It is preferable to set so that When used as a lithographic printing plate, this is generally 0.05 to 30 parts by weight, preferably 0.1 to 20 parts by weight, more preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the photosensitive layer component. It is the range of mass parts.

  In addition, it is estimated that the sensitizing dye used in the present invention improves the electron transfer efficiency to the activator compound when the oxidation potential and the oxidation potential in the excited state are negatively large, resulting in higher sensitivity. For this reason, it is preferable that the oxidation potential of the sensitizing dye in the excited state (denoted by Eox * for the sake of convenience) is more negative than −1.7. Further, when used as a lithographic printing plate, Eox * is desirably −1.9 to −2.3, more preferably −2.1 to −2.3.

<(C) Addition polymerizable compound having an ethylenically unsaturated double bond>
The photosensitive composition of the present invention contains an addition polymerizable compound having at least one ethylenically unsaturated double bond in addition to the above-described photopolymerization initiation system. More specifically, the addition polymerizable compound having an ethylenically unsaturated double bond is selected from compounds having at least one, preferably two or more terminal ethylenically unsaturated bonds. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention.
These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is 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 unsaturated carboxylic acid ester having an electrophilic substituent such as an isocyanato group or an epoxy group, an addition reaction product of an amide with a monofunctional or polyfunctional alcohol, an amine or a thiol, a halogen group, Also suitable are substitution reaction products of unsaturated carboxylic acid esters and amides with monofunctional or polyfunctional alcohols, amines and thiols having a leaving substituent such as a tosyloxy group.
As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of 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, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 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 hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) 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, Those having an aromatic skeleton described in JP-A-59-5241 and JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used.
Furthermore, the ester monomers described above can also be used as a mixture.

Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids 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-based monomers include those having a cyclohexylene structure described in JP-B No. 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. A vinyl urethane compound containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following formula (VIII) to a polyisocyanate compound having two or more isocyanate groups. Etc.

_{CH 2 = C (R) COOCH} 2 CH (R ') OH (VIII)
(However, R and R ′ represent H or CH _3. )

  Further, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, 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, by using addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, JP-A-1-105238 Can obtain a photopolymerizable (photosensitive) composition having an excellent photosensitive speed.

  Other examples include reacting polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191 and JP-B-52-30490. And polyfunctional acrylates and methacrylates such as epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337 and JP-B-1-40336, vinylphosphonic acid compounds described in JP-A-2-25493, and the like are listed. be able to. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

  For these addition-polymerizable compounds, details on how to use them, such as what type of structure is used, whether they are used alone or in combination, and how much is added, according to the performance design of the final photosensitive material, Can be set arbitrarily. For example, it is selected from the following viewpoints. From the viewpoint of the speed of photosensitivity, a structure having a high unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. In addition, when used in a photosensitive layer for a lithographic printing plate, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic acid). A method of adjusting both photosensitivity and strength is also effective by using a combination of an ester, a methacrylic ester, a styrene compound, or a vinyl ether compound. A compound having a large molecular weight or a compound having a high hydrophobicity is not preferable in terms of development speed and precipitation in a developing solution, although it is excellent in photosensitive speed and film strength. In addition, the selection of the addition polymerization compound is also required for compatibility and dispersibility with other components in the photosensitive layer (for example, the binder polymer described later, the photopolymerization initiator (system) described above, the colorant described later, etc.). -The usage method is an important factor. For example, compatibility may be improved by using a low-purity compound or using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the support, overcoat layer and the like.

  As for the compounding ratio of the addition polymerizable compound in the photosensitive layer, a larger amount is advantageous in terms of sensitivity. However, when the amount is too large, undesirable phase separation may occur or the production process due to the adhesiveness of the photosensitive layer may occur. Problems such as transfer of photosensitive material components (manufacturing defects due to adhesion) and precipitation from the developer may occur. From these viewpoints, the preferable blending ratio is often 5 to 80% by mass, preferably 25 to 75% by mass with respect to the total components of the composition. These may be used alone or in combination of two or more. In addition, the use method of the addition polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.

<(D) Binder polymer>
When the photosensitive composition of the present invention is applied to the photosensitive layer of the lithographic printing plate precursor as a preferred embodiment thereof, a binder polymer is used in addition to the above-mentioned photopolymerization initiation system and addition polymerizable compound. Is preferred.
The binder preferably contains a linear organic high molecular polymer. Any such “linear organic polymer” may be used. Preferably, a linear organic high molecular weight polymer that is soluble in water or weakly alkaline water or swellable that enables water development or weak alkaline water development is selected.
The linear organic high molecular polymer is selected and used not only as a film-forming agent for the composition but also according to its use as water, weak alkaline water or an organic solvent developer. For example, when a water-soluble organic polymer is used, water development is possible. Examples of such linear organic high molecular polymers include addition polymers having a carboxylic acid group in the side chain, such as JP 59-44615, JP-B 54-34327, JP-B 58-12777, and JP-B. 54-25957, JP-A-54-92723, JP-A-59-53836, JP-A-59-71048, ie, methacrylic acid copolymer, acrylic acid copolymer , Itaconic acid copolymer, crotonic acid copolymer, maleic acid copolymer, and partially esterified maleic acid copolymer. Similarly, there is an acidic cellulose derivative having a carboxylic acid group in the side chain. In addition, those obtained by adding a cyclic acid anhydride to an addition polymer having a hydroxyl group are useful.

  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] are preferred because they are excellent in the balance of film strength, sensitivity and developability.

  In addition, Japanese Patent Publication No. 7-2004, Japanese Patent Publication No. 7-120041, Japanese Patent Publication No. 7-120042, Japanese Patent Publication No. 8-12424, Japanese Patent Laid-Open No. 63-287944, Japanese Patent Laid-Open No. 63-287947, Japanese Patent Laid-Open No. The urethane-based binder polymer containing an acid group described in each publication of JP 271741 and JP-A No. 13-312062 is very excellent in strength, and is advantageous in terms of printing durability and suitability for low exposure. is there. A binder having an amide group described in JP-A No. 11-171907 is suitable because it has both excellent developability and film strength.

  In addition, polyvinyl pyrrolidone, polyethylene oxide, and the like are useful as the water-soluble linear organic polymer. In order to increase the strength of the cured film, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, and the like are also useful. These linear organic high molecular polymers can be mixed in an arbitrary amount in the entire composition. However, when it exceeds 90% by mass, a preferable result is not given in terms of the strength of the formed image. Preferably it is 30-85 mass%. The photopolymerizable compound having an ethylenically unsaturated double bond and the linear organic polymer are preferably in the range of 1/9 to 7/3 by mass ratio. In a preferred embodiment, a binder polymer that does not require water and is soluble in alkali is used. By doing so, an organic solvent that is not environmentally preferable is not used as the developer, or the amount can be limited to a very small amount. In such a method of use, the acid value of the binder polymer (the acid content per gram of the polymer expressed as a chemical equivalent number) and the molecular weight are appropriately selected from the viewpoint of image strength and developability. The preferred acid value is 0.4 to 3.0 meq / g, the preferred molecular weight is in the range of 3000 to 500,000, more preferably the acid value is 0.6 to 2.0 and the molecular weight is in the range of 10,000 to 300,000. It is.

<(E) Other ingredients>
In order to use the photosensitive composition of the present invention as a photosensitive layer of an image recording material such as a lithographic printing plate precursor, other components suitable for its use, production method and the like can be added as appropriate.
Hereinafter, preferred additives will be exemplified.

(E1) Co-sensitizer The sensitivity of the photosensitive composition of the present invention can be further improved by using a certain additive (hereinafter referred to as a co-sensitizer). These mechanisms of action are not clear, but many are thought to be based on the following chemical processes. That is, a photoreaction initiated by light absorption of the above-described photopolymerization initiation system, and various intermediate active species (radicals, peroxides, oxidizing agents, reducing agents, etc.) generated in the course of the subsequent addition polymerization reaction, It is presumed that the co-sensitizer reacts to generate a new active radical. These can be broadly divided into (a) those that can be reduced to generate active radicals, (b) those that can be oxidized to generate active radicals, and (c) radicals that are more active by reacting with less active radicals. Can be classified into those that act as chain transfer agents, but there is often no generality as to which of these individual compounds belong.

(A) Compound that is reduced to produce an active radical Compound having a carbon-halogen bond: It is considered that an active radical is generated by reductive cleavage of the carbon-halogen bond. Specifically, for example, trihalomethyl-s-triazines and trihalomethyloxadiazoles can be preferably used.
Compound having nitrogen-nitrogen bond: It is considered that the nitrogen-nitrogen bond is reductively cleaved to generate an active radical. Specifically, hexaarylbiimidazoles and the like are preferably used.
Compound having oxygen-oxygen bond: It is considered that the oxygen-oxygen bond is reductively cleaved to generate an active radical. Specifically, for example, organic peroxides are preferably used.
Onium compounds: It is considered that carbon-hetero bonds and oxygen-nitrogen bonds are reductively cleaved to generate active radicals. Specifically, for example, diaryliodonium salts, triarylsulfonium salts, N-alkoxypyridinium (azinium) salts and the like are preferably used.
Ferrocene and iron arene complexes: An active radical can be reductively generated.

(B) Compound which is oxidized to generate an active radical Alkylate complex: It is considered that a carbon-hetero bond is oxidatively cleaved to generate an active radical. Specifically, for example, triarylalkyl borates are preferably used.
Alkylamine compound: It is considered that the C—X bond on carbon adjacent to nitrogen is cleaved by oxidation to generate an active radical. X is preferably a hydrogen atom, a carboxyl group, a trimethylsilyl group, a benzyl group or the like. Specific examples include ethanolamines, N-phenylglycines, N-trimethylsilylmethylanilines, and the like.
Sulfur-containing and tin-containing compounds: Compounds in which the nitrogen atoms of the above-described amines are replaced with sulfur atoms and tin atoms can generate active radicals by the same action. Further, a compound having an SS bond is also known to be sensitized by SS cleavage.
α-Substituted methylcarbonyl compound: An active radical can be generated by oxidative cleavage of the carbonyl-α carbon bond. Moreover, what converted carbonyl into the oxime ether also shows the same effect | action. Specifically, 2-alkyl-1- [4- (alkylthio) phenyl] -2-morpholinopronone-1 and these and a hydroxylamine were reacted, and then N—OH was etherified. Oxime ethers can be listed.
Sulfinic acid salts: An active radical can be reductively generated. Specific examples include sodium arylsulfinate.

(C) Compounds that react with radicals to convert to highly active radicals or act as chain transfer agents Compounds that react with radicals to convert to highly active radicals or act as chain transfer agents include, for example, SH, PH in the molecule , SiH, and GeH are used. These can generate hydrogen by donating hydrogen to a low-activity radical species to generate radicals, or after being oxidized and deprotonated. Specifically, 2-mercaptobenzimidazoles etc. are mentioned, for example.

  Many more specific examples of these co-sensitizers are described, for example, in JP-A-9-236913 as additives for the purpose of improving sensitivity. Some examples are shown below, but the present invention is not limited thereto.

  These co-sensitizers can also be subjected to various chemical modifications for improving the characteristics of the photosensitive layer of the lithographic printing plate precursor as in the case of the sensitizing dye. For example, bonds with sensitizing dyes, titanocene, addition polymerizable unsaturated compounds and other radical generating parts, introduction of hydrophilic sites, improved compatibility, introduction of substituents for suppressing crystal precipitation, substituents for improving adhesion Methods such as introduction and polymerization can be used. These co-sensitizers can be used alone or in combination of two or more. The amount used is 0.05 to 100 parts by mass, preferably 1 to 80 parts by mass, and more preferably 3 to 50 parts by mass with respect to 100 parts by mass of the compound having an ethylenically unsaturated double bond.

(E2) Thermal polymerization inhibitor In addition to the above basic components, the photosensitive composition of the present invention does not require a compound having an ethylenically unsaturated double bond that can be polymerized during its production or storage. In order to prevent thermal polymerization, it is desirable to add a small amount of a thermal polymerization inhibitor. Suitable 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-nitrosophenylhydroxyamine primary cerium salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the entire composition. In addition, when applied as a photosensitive layer such as a lithographic printing plate precursor, a higher fatty acid derivative such as behenic acid or behenic acid amide is added as necessary to prevent polymerization inhibition by oxygen, and after coating, It may be unevenly distributed on the surface of the photosensitive layer in the course of drying. The amount of the higher fatty acid derivative added is preferably about 0.5% by mass to about 10% by mass of the total composition.

(E3) Colorant When the photosensitive composition of the present invention is used as a photosensitive layer of an image recording material such as a lithographic printing plate precursor, a dye or pigment colorant is further added for the purpose of coloring the photosensitive layer. Also good. As a result, it is possible to improve the so-called plate inspection properties such as visibility after plate making and suitability for an image density measuring machine as a lithographic printing plate precursor.
As a colorant, since many dyes cause a decrease in the sensitivity of the photopolymerization type photosensitive layer, it is particularly preferable to use a pigment. Specific examples include pigments such as phthalocyanine pigments, azo pigments, carbon black and titanium oxide, and dyes such as ethyl violet, crystal violet, azo dyes, anthraquinone 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 composition.

(E4) Other additives When the photosensitive composition of the present invention is used in a photosensitive layer such as a lithographic printing plate precursor, an inorganic filler, other plasticizer, You may add well-known additives, such as a fat-sensitizing agent which can improve the ink inking property of the photosensitive layer surface.
Examples of plasticizers include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, and triacetyl glycerin. 10 mass% or less can be added with respect to the total mass of the compound which has an ionic unsaturated double bond, and a binder polymer.

In addition, for the purpose of improving the film strength (printing durability) of the photosensitive layer of a lithographic printing plate precursor described later, a UV initiator, a thermal crosslinking agent, etc. Can also be added.
In addition, it is possible to provide an additive and an intermediate layer for improving the adhesion between the photosensitive layer and the support and for improving the development removability of the unexposed photosensitive layer. For example, by adding or undercoating a compound having a relatively strong interaction with a substrate described later, such as a compound having a diazonium structure or a phosphone compound, adhesion can be improved and printing durability can be increased. By adding or undercoating with a hydrophilic polymer such as acrylic acid or polysulfonic acid, the developability of the non-image area is improved, and the stain resistance can be improved.

<(F) Image recording material>
One of the main uses of the photosensitive composition of the present invention is to prepare an image recording material having a photosensitive layer containing the photosensitive composition of the present invention on a support.
One example of the image recording material is a lithographic printing plate precursor.
In order to obtain a lithographic printing plate precursor, it is desirable to provide a photosensitive layer made of the photosensitive composition on a support having a hydrophilic surface. As the hydrophilic support, a conventionally known hydrophilic support used for a lithographic printing plate precursor can be used without limitation.
The support used is preferably a dimensionally stable plate, for example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc). , Copper, etc.), plastic films (for example, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.) Paper or plastic film, etc., laminated or vapor-deposited with such metals is included, and appropriate physical and chemical treatments are applied to these surfaces for the purpose of imparting hydrophilicity and improving strength as necessary. You may give it.

  In particular, preferred supports include paper, polyester film or aluminum plate, among which dimensional stability is good, relatively inexpensive, and a surface with excellent hydrophilicity and strength is provided by surface treatment as required. An aluminum plate which can be used is particularly preferred. 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.

  A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10% by mass. Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements. Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is usually about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

In the case of a support having a surface of metal, particularly aluminum, roughening (graining) treatment, immersion treatment in an aqueous solution of sodium silicate, potassium fluoride zirconate, phosphate, etc., or anodic oxidation treatment, etc. It is preferable that surface treatment is performed.
The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. In addition, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in an electrolytic solution such as hydrochloric acid or nitric acid. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used. Further, prior to roughening the aluminum plate, for example, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution, or the like is performed in order to remove the rolling oil on the surface, if desired.

Furthermore, an aluminum plate that has been roughened and then immersed in an aqueous sodium silicate solution can be preferably used. As described in Japanese Patent Publication No. 47-5125, an aluminum plate is anodized and then immersed in an aqueous solution of an alkali metal silicate is preferably used. The anodizing treatment is carried out in an electrolytic solution in which an inorganic acid such as phosphoric acid, chromic acid, sulfuric acid or boric acid, or an organic acid such as oxalic acid or sulfamic acid, or a salt solution thereof, or a combination of two or more thereof, is used. This is carried out by passing an electric current using the aluminum plate as an anode.
Silicate electrodeposition as described in US Pat. No. 3,658,662 is also effective.

Further, a support body provided with electrolytic grains as disclosed in JP-B-46-27481, JP-A-52-58602, JP-A-52-30503, and the above-described anodizing treatment and sodium silicate treatment. A surface treatment in combination with is also useful.
Further, those obtained by performing mechanical surface roughening, chemical etching, electrolytic graining, anodizing treatment and sodium silicate treatment in this order as disclosed in JP-A-56-28893 are also suitable.

Furthermore, after performing these treatments, water-soluble resins such as polyvinylphosphonic acid, polymers and copolymers having sulfonic acid groups in the side chain, polyacrylic acid, water-soluble metal salts (for example, zinc borate) or Those having a primer such as a yellow dye or an amine salt are also suitable.
Further, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A-7-159983 is covalently used.

Other preferred examples include those in which a water-resistant hydrophilic layer is provided as a surface layer on an arbitrary support. Examples of such a surface layer include a layer composed of an inorganic pigment and a binder described in US Pat. No. 3,055,295 and JP-A-56-13168, and a hydrophilic swelling described in JP-A-9-80744. A layer, a sol-gel film made of titanium oxide, polyvinyl alcohol, silicic acid or the like described in JP-A-8-507727 can be raised.
These hydrophilic treatments are performed to make the surface of the support hydrophilic, in order to prevent harmful reactions of the photosensitive composition provided thereon, and to improve the adhesion of the photosensitive layer, etc. It is given for.

  When the photosensitive composition of the present invention is applied on a support as a photosensitive layer of an image recording material such as a lithographic printing plate precursor, it is used after being dissolved in various organic solvents. Solvents used here include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, 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, Ethylene 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-butyrolactone, methyl lactate, lactic acid There are ethyl and the like. These solvents can be used alone or in combination. The solid content in the coating solution is suitably 2 to 50% by mass.

The support coating amount of the photosensitive layer mainly affects the sensitivity of the photosensitive layer, the developability, the strength and printing durability of the exposed film, and is preferably selected as appropriate according to the application. When the coating amount is too small, the printing durability is not sufficient. On the other hand, if the amount is too large, the sensitivity is lowered, it takes time for exposure, and a longer time is required for development processing, which is not preferable. For the lithographic printing plate for scanning exposure which is the main purpose of use of the photosensitive composition of the present invention, the coating amount is suitably in the range of about 0.1 g / m ² to about 10 g / m ² in terms of the mass after drying. is there. More preferably from 0.5 to 5 g / m ^2.

<(G) Protective layer>
A desirable use mode of the photosensitive composition of the present invention is to use it as a lithographic printing plate for scanning exposure. Since the lithographic printing plate for scanning exposure is usually exposed in the air, it is preferable to further provide a protective layer on the layer made of the photosensitive composition.
The protective layer prevents exposure of low molecular weight compounds such as oxygen and basic substances present in the atmosphere that hinder the image formation reaction caused by exposure in the photosensitive layer, and enables exposure in the atmosphere. To do. Therefore, the properties desired for such a protective layer are low permeability of low-molecular compounds such as oxygen, and further, transmission of light used for exposure is not substantially inhibited, and adhesion to the photosensitive layer is excellent. And it is desirable that it can be easily removed in the development process after exposure. Such a device relating to the protective layer has been conventionally devised, and is described in detail in US Pat. No. 3,458,311 and JP-A-55-49729.

  As a material that can be used for the protective layer, for example, a water-soluble polymer compound having relatively excellent crystallinity is preferably used. Specifically, polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, Water-soluble polymers such as acrylic acid are known, but among these, the use of polyvinyl alcohol as a main component gives the best results in terms of 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. Specific examples of polyvinyl alcohol include those having a hydrolysis rate of 71 to 100% and a molecular weight in the range of 300 to 2400.

  Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, 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, L-8 and the like.

  Components of the protective layer (selection of PVA, use of additives), coating amount, and the like 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 the unsubstituted vinyl alcohol unit 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, there arises a problem that unnecessary polymerization reaction occurs during production and raw storage, and unnecessary fogging and image line thickening occur during image exposure. 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 part causes defects such as poor film hardening due to inhibition of oxygen polymerization.

  On the other hand, various proposals have been made to improve the adhesion between these two layers. For example, sufficient adhesiveness can be obtained by mixing 20 to 60% by mass of an acrylic emulsion or a water-insoluble vinylpyrrolidone-vinyl acetate copolymer in a hydrophilic polymer made of polyvinyl alcohol and laminating the polymer layer. can get. Any of these known techniques can be applied to the protective layer in the present invention. Such a coating method for the protective layer is described in detail, for example, in US Pat. No. 3,458,311 and JP-A-55-49729.

  Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (such as a water-soluble dye) that is excellent in the transmission of light from 350 nm to 450 nm and that can absorb light of 500 nm or more, which is used for exposure, it does not cause a decrease in sensitivity and is suitable for safelight. Can be further enhanced.

<(H) Image recording method>
When the photosensitive composition of the present invention is used as an image recording material such as an original plate for a lithographic printing plate, it is usually exposed to an image and then an unexposed portion of the photosensitive layer is removed with a developer to obtain an image.
When these photosensitive compositions are used for lithographic printing plate precursors, preferred developers include those described in JP-B-57-7427, such as sodium silicate and silicate. Potassium, sodium hydroxide, potassium hydroxide, lithium hydroxide, tribasic sodium phosphate, dibasic sodium phosphate, tribasic ammonium phosphate, dibasic ammonium phosphate, sodium metasilicate, sodium bicarbonate, aqueous ammonia, etc. An inorganic alkali agent such as this and an aqueous solution of an organic alkali agent such as monoethanolamine or diethanolamine are suitable. The alkali solution is added so that the concentration thereof is 0.1 to 10% by mass, preferably 0.5 to 5% by mass, but the developing solution that can be used in the present invention is not limited thereto. .

  In addition, such an aqueous developer solution may contain a small amount of a surfactant, an organic solvent such as benzyl alcohol, 2-phenoxyethanol, and 2-butoxyethanol as necessary. Examples thereof include those described in US Pat. Nos. 3,375,171 and 3,615,480. Further, the developers described in JP-A-50-26601, 58-54341, JP-B-56-39464, and 56-42860 are also excellent.

As a particularly preferred developer, a nonionic compound represented by the following formula described in JP-A No. 2002-202616 is contained, the pH is 10 to 14, and the conductivity is 3 to 30 mS / cm. The developing solution which has is mentioned.
A-W
(In the formula, A represents a hydrophobic organic group having a LogP of AH of 1.5 or more, and W represents a nonionic hydrophilic organic group having a LogP of less than 1.0.)

  In addition, as a plate-making process of a lithographic printing plate from a lithographic printing plate precursor using the photosensitive composition of the present invention as a photosensitive layer, the entire surface can be used before exposure, during exposure, and from exposure to development as necessary. May be heated. By such heating, the image forming reaction in the photosensitive layer is promoted, and advantages such as improvement in sensitivity and printing durability and stabilization of sensitivity may occur. Further, for the purpose of improving the image strength and printing durability, it is also effective to subject the developed image to full post heating or full exposure. Usually, the heating before development is preferably performed under a mild condition of 150 ° C. or less. If the temperature is too high, problems such as covering up to the non-image area occur. Very strong conditions are used for heating after development. Usually, it is the range of 200-500 degreeC. If the temperature is low, sufficient image strengthening action cannot be obtained. If the temperature is too high, problems such as deterioration of the support and thermal decomposition of the image area occur.

  As a method for exposing a lithographic printing plate precursor using the photosensitive composition of the present invention for a photosensitive layer, a known method can be used without limitation. The wavelength of the desirable light source is 450 nm or less, more desirably 350 nm to 450 nm, and specifically, an InGaN-based semiconductor laser is suitable. The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like. Further, the photosensitive layer component can be made soluble in neutral water or weak alkaline water by using a highly water-soluble component, and the lithographic printing plate precursor having such a configuration is used in a printing machine. After loading on top, exposure-development can be performed on the machine.

Further, as other exposure light rays for the photosensitive composition according to the present invention, ultrahigh pressure, high pressure, medium pressure, low pressure mercury lamps, chemical lamps, carbon arc lamps, xenon lamps, metal halide lamps, various visible and ultraviolet laser lamps. Fluorescent lamps, tungsten lamps, sunlight, etc. can also be used.
As available laser light sources of 350 nm to 450 nm, the following can be used.
As a gas laser, Ar ion laser (364 nm, 351 nm, 10 mW to 1 W), Kr ion laser (356 nm, 351 nm, 10 mW to 1 W), He—Cd laser (441 nm, 325 nm, 1 mW to 100 mW), and solid laser as Nd: YAG (YVO ₄ ) and SHG crystal × two combinations (355 nm, 5 mW to 1 W), Cr: LiSAF and SHG crystal combination (430 nm, 10 mW), as a semiconductor laser system, a KNbO ₃ ring resonator (430 nm, 30 mW), Combination of waveguide type wavelength conversion element and AlGaAs, InGaAs semiconductor (380 nm to 450 nm, 5 mW to 100 mW), combination of waveguide type wavelength conversion element and AlGaInP, AlGaAs semiconductor (300 nm to 350 nm, 5 mW to 100 mW), A lGaInN (350 nm to 450 nm, 5 mW to 30 mW) In addition, N ₂ laser (337 nm, pulse 0.1 to 10 mJ), XeF (351 nm, pulse 10 to 250 mJ) as a pulse laser. Among these, AlGaInN semiconductor lasers (commercially available InGaN-based semiconductor lasers 400 to 410 nm, 5 to 30 mW) are preferable in terms of wavelength characteristics and cost.

Further, as the lithographic printing plate exposure apparatus of the scanning exposure method, there are an inner drum method, an outer drum method, and a flat bed method as an exposure mechanism, and a light source that can continuously oscillate among the light sources can be preferably used. . Practically, the following exposure apparatus is particularly preferable in terms of the relationship between the photosensitive material sensitivity and the plate making time.
・ Single-beam to triple-beam exposure equipment that uses one or more gas lasers or solid-state laser light sources so that it becomes a semiconductor laser with a total output of 20 mW or more with an internal drum system. ・ A total output of 20 mW or more with a flatbed system. Multi-beam (1 to 10) exposure equipment that uses one or more semiconductor lasers, gas lasers, or solid-state lasers ・ Use one or more semiconductor lasers, gas lasers, or solid-state lasers to achieve a total output of 20 mW or more with the external drum system Multi-beam (1 to 9) exposure devices ・ More than multi-beam (10 or more) exposure devices that use one or more semiconductor lasers or solid-state lasers so that the total output is 20 mW or more in the external drum system in the lithographic printing plate of such a laser direct drawing type, generally the photosensitive material sensitivity X (J / cm ^2), the exposure of the photosensitive material Product S (cm ^2), the laser light source 1 power q (W), Formula (eq1) is established between the laser number n, the total exposure time t (s).
X · S = n · q · t (eq 1)

i) In the case of the internal drum (single beam) system, the laser rotation speed f (radians / s), the sub-scanning length Lx (cm) of the photosensitive material, the resolution Z (dots / cm), and the total exposure time t (s) In general, equation (eq 2) holds.
f · Z · t = Lx (eq 2)

ii) External drum (multi-beam) system Drum rotation speed F (radians / s), photosensitive material sub-scanning length Lx (cm), resolution Z (dots / cm), total exposure time t (s), number of beams In general, formula (eq 3) is established during (n).
F.Z.n.t = Lx (eq 3)

iii) Flat head (multi-beam) system Polygon mirror rotation speed H (radians / s), photosensitive material sub-scanning length Lx (cm), resolution Z (dots / cm), total exposure time t (s), Equation (eq 4) is generally established between the number of beams (n).
F.Z.n.t = Lx (eq 4)

Resolution (2560 dpi) required for an actual printing plate, plate size (A1 / B1, sub-scanning length 42 inch), exposure conditions of about 20 sheets / hour and photosensitive characteristics of the photosensitive composition of the present invention (photosensitive wavelength, By substituting (sensitivity: about 0.1 mJ / cm ² ) into the above formula, the photosensitive material using the photosensitive composition of the present invention can be combined with a multi-beam exposure method using a laser having a total output of 20 mW or more. It can be seen that it is particularly preferable. Further, by combining operability, cost, etc., a combination with an external drum type semiconductor laser multi-beam (10 or more) exposure apparatus is most preferable.

  Moreover, as a use of the photosensitive composition by this invention, it can apply without a restriction | limiting to what is widely known as a use of photocurable resin besides the planographic printing plate for scanning exposure. For example, a highly sensitive optical modeling material can be obtained by applying to a liquid photopolymerizable composition used in combination with a cationic polymerizable compound as necessary. Further, a hologram material can be obtained by utilizing a change in refractive index accompanying photopolymerization. It can be applied to various transfer materials (peeling sensitive material, toner developing sensitive material, etc.) by utilizing the change in surface adhesiveness accompanying photopolymerization. It can also be applied to photocuring of microcapsules. It can also be applied to the production of electronic materials such as photoresists, and photocurable resin materials such as inks, paints, and adhesives.

  Furthermore, the photopolymerization initiation system comprising the hexaarylbiimidazole type compound represented by the general formula (I) and the sensitizing dye contained in the photosensitive composition of the present invention has excellent photosensitivity and excellent stability. It is a photopolymerization initiating system, and various utilization methods can be used in addition to the photosensitive composition detailed above. For example, radical generation with high efficiency by light can cause, for example, oxidative color development of a triphenylmethane leuco dye with high sensitivity. In addition, a decoloring reaction due to radical addition can be caused for certain polymethine dyes. In addition, since the photopolymerization initiation system generates an acid component simultaneously with radicals by light, it can be decomposed by an acid, a compound that changes absorption by an acid, a resin composition that undergoes a crosslinking reaction by an acid, and can improve solubility. By combining with a resin composition, a highly sensitive image forming material can be produced.

Hereinafter, the present invention will be described with reference to examples for producing a lithographic printing plate, but the present invention is not limited to these examples.
[Examples 1 to 17 and Comparative Examples 1 to 4]
(Preparation of support)
An aluminum plate having a thickness of 0.3 mm was etched by being immersed in 10% by mass sodium hydroxide at 60 ° C. for 25 seconds, washed with running water, neutralized with 20% by mass nitric acid, and then washed with water. This was subjected to an electrolytic surface roughening treatment in a 1% by mass nitric acid aqueous solution using a sinusoidal alternating waveform current at an anode time electricity of 300 coulomb / dm ² . Subsequently, after dipping in a 1% by mass aqueous sodium hydroxide solution at 40 ° C. for 5 seconds and then in a 30% by mass sulfuric acid aqueous solution and desmutting at 60 ° C. for 40 seconds, the current density in a 20% by mass sulfuric acid aqueous solution was 2A / current density. At dm ² , the anodization treatment was performed for 2 minutes so that the thickness of the anodized film was 2.7 g / m ² . When the surface roughness was measured, it was 0.3 μm (Ra display according to JIS B0601).

(Preparation of back coat layer)
The following sol-gel reaction liquid was applied to the back surface of the substrate thus treated with a bar coater, dried at 100 ° C. for 1 minute, and a support provided with a backcoat layer having a coating amount after drying of 70 mg / m ^2. It was created.

Sol-gel reaction liquid When the following component (A) was mixed and stirred, heat generation started in about 5 minutes. After reacting for 60 minutes, a backcoat coating solution was prepared by adding a solution comprising component (B).

Component (A) Tetraethyl silicate 55 parts by weight Water 25 parts by weight Methanol 10 parts by weight Phosphoric acid 0.05 parts by weight

Component (B) Pyrogallol formaldehyde condensation resin (molecular weight 2000) 6 parts by mass Dimethyl phthalate 6 parts by mass Fluorosurfactant 0.7 parts by mass (N-butylperfluorooctanesulfonamidoethyl acrylate / polyoxyethylene acrylate copolymer: molecular weight 20,000)
Methanol silica sol (manufactured by Nissan Chemical Industries, Ltd., methanol 30% by mass)
50 parts by mass Methanol 800 parts by mass

(Preparation of photosensitive layer)
On the aluminum plate thus treated, a photopolymerizable photosensitive composition having the following composition was applied so that the dry coating amount was 1.0 g / m ^2, and dried at 80 ° C. for 2 minutes to form a photosensitive layer. Formed.

・上記重合性化合物 １．５ ｇ
・アリルメタクリレート／メタクリル酸／Ｎ−イソプロピルアクリルアミド共重合体
（共重合モル比６７／１３／２０） ２．０ ｇ
・光重合開始系 （表１中に記載）
増感色素
開始剤化合物
共増感剤
・フッ素系ノニオン界面活性剤（Ｆ−１７７Ｐ） ０．０２ ｇ
・熱重合禁止剤
（Ｎ−ニトロソフェニルヒドロキシルアミンアルミニウム塩） ０．０１ ｇ
・顔料分散物 ２．０ ｇ
Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：６ １５重量部
アリルメタクリレート／メタクリル酸共重合 １０重量部
（共重合モル比８３／１７）
シクロヘキサノン １５重量部
メトキシプロピルアセテート ２０重量部
プロピレングリコールモノメチルエーテル ４０重量部
・メチルエチルケトン ２０．０ ｇ
・プロピレングリコールモノメチルエーテル ２０．０ ｇ

・ The above polymerizable compound 1.5 g
Allyl methacrylate / methacrylic acid / N-isopropylacrylamide copolymer (copolymerization molar ratio 67/13/20) 2.0 g
-Photopolymerization initiation system (described in Table 1)
Sensitizing dye initiator compound
Co-sensitizer / Fluorine nonionic surfactant (F-177P) 0.02 g
-Thermal polymerization inhibitor (N-nitrosophenylhydroxylamine aluminum salt) 0.01 g
・ Pigment dispersion 2.0 g
Pigment Blue 15: 6 15 parts by weight Allyl methacrylate / methacrylic acid copolymer 10 parts by weight (copolymerization molar ratio 83/17)
Cyclohexanone 15 parts by weight Methoxypropyl acetate 20 parts by weight Propylene glycol monomethyl ether 40 parts by weight Methyl ethyl ketone 20.0 g
・ Propylene glycol monomethyl ether 20.0 g

(Preparation of protective layer)
On this photosensitive layer, a 3% by weight aqueous solution of polyvinyl alcohol (saponification degree: 98 mol%, polymerization degree: 550) was applied such that the dry coating weight was 2 g / m ² and dried at 100 ° C. for 2 minutes.

(Evaluation of sensitivity: 405 nm exposure)
A Fuji step guide made by Fuji Photo Film Co., Ltd. (gray scale whose transmission optical density changes discontinuously at Δ = 0.15) was brought into close contact with the obtained lithographic printing plate precursor, and an optical filter (Kenko) was used. Using a xenon lamp through BP-53 (for 532 nm) and BP-40 (for 405 nm), exposure was performed so as to obtain a known exposure energy. As the optical filter, Kenko BP-53 and 40 capable of exposure with monochromatic light at 532 or 405 nm were used for the purpose of estimating the suitability for exposure to a short-wave semiconductor laser. Thereafter, the film was immersed in a developer having the following composition at 25 ° C. for 10 seconds, developed, and the sensitivity (clear sensitivity) was calculated from the maximum number of steps at which the image was completely removed (Table 1). Here, the clear sensitivity represents the minimum energy required for image formation, and the lower this value, the higher the sensitivity.

(Developer composition)
1K potassium silicate 2.4g
Potassium hydroxide 0.2g
Compound of the following formula 1 5.0 g
91.3g of water
Ethylenediaminetetraacetic acid, 4Na salt 0.1g

ＮａＯＨ滴定により求めた実測酸価 １．０８ｍｅｑ／ｇ
ＧＰＣ測定より求めた重量平均分子量 ５．２万

Measured acid value determined by NaOH titration 1.08 meq / g
Weight average molecular weight determined by GPC measurement 52,000

(Evaluation of storage stability)
Storage stability was evaluated by comparing the sensitivity immediately after creation of the lithographic printing plate prepared in the configuration described in the Examples under the following two conditions with the sensitivity after aging under forced conditions.
(I) Clear sensitivity obtained by exposure and development immediately after the application is completed (ii) Clear sensitivity obtained by exposure and development after storage under forced storage conditions at 60 ° C. for 10 days The clear sensitivity is the same as that described above. The difference between the sensitivity of (i) and the sensitivity of (ii) ((ii) / (i)) was defined as the clear sensitivity ratio. The closer this value is to 1, the smaller the change in image forming sensitivity between the time-sensitive material and the time-sensitive material, and it can be said that the storage stability is high.

According to the results in Table 1 above, when the photosensitive composition of the present invention using a specific hexaarylimidazole compound as an initiator is used, a highly sensitive lithographic printing plate precursor can be prepared. Furthermore, even after these lithographic printing plate precursors were stored under forced aging conditions (clear sensitivity ratio), excellent sensitivity was maintained. On the other hand, the sensitivity of the lithographic printing plate precursor using the photosensitive compositions of Comparative Examples 1 to 4 was low, and the clear sensitivity ratio after storage under forced aging conditions was also low.
Further, it was found from the comparison between Examples 1 and 18 that the influence of the added amount of the initiator on the sensitivity was great. Moreover, in Example 4 which considered solvent solubility, it became the result which shows the highest sensitivity.

Furthermore, it can be seen from the comparison of the examples that a 6-membered ring structure in which the aromatic rings at positions 4 and 5 of the imidazole ring are directly connected is most excellent as the cyclic structure. This is presumably because the conjugate stabilization effect of the generated radicals is maximized in a six-membered ring structure that does not have excessive strain.
Moreover, as shown in Example 7, it is also useful for imparting solvent solubility to introduce a halogen (in this case, fluorine) atom into the para-position (4-position) of the aromatic ring at positions 4 and 5 of the imidazole ring. It was found that the sensitivity could be increased because the amount could be increased.
In addition, clear sensitivity and sensitivity ratio were better when the aminostyryl type sensitizing dye (H-1) was used than when the H-2 or H-3 sensitizing dye was used (Examples). 1, 16, 17).

  In addition, the structure of the hexaarylbiimidazole type compound in this example is exemplified in this specification, and the structures of the other compounds are as follows.

Claims (9)

(A) a hexaarylbiimidazole type compound having a structure represented by the following general formula (II) or (III):
(B) a sensitizing dye having an absorption maximum λ _max at 350 nm to 850 nm, and (C) an addition polymerizable compound having an ethylenically unsaturated double bond,
Containing the photosensitive composition.

(II) (III)

(In General Formulas (II) and (III), R _{1 to} R ₃ and R _{5 to} R ₇ each independently represents a monovalent non-metallic atomic group. M is an integer of 0 to 3 each independently. R _{1 to} R ₃ and R _{5 to} R ₇ can be independently bonded to each other to form an aliphatic or aromatic ring, provided that in the general formula (II), R 1 Any of _{1 to} R ₃ , R _{5 to} R ₇ is an alkoxy group, an alkoxycarbonyl group, or an alkyl group, and any of R ₂ , R ₃ , R ₆ , and R ₇ is an alkoxy group, an alkoxycarbonyl group, or In the case of an alkyl group, m representing the number of the group is not 0. X ₁ and X ₂ are each independently a group consisting of a halogen atom, a cyano group, an alkoxycarbonyl group, a fluorine-substituted alkyl group, and an acyl group. And at least one substituent selected from Y ₁ and Y. ₂ represents —O—, —SO—, —SO ₂ —, —NR ₉ —, —CR ₁₀ R ₁₁ —, —S—, and R _{9 to} R ₁₁ are defined as R _{1 to} R ₃ , R ₅ to it is the same as R _7.) In formula (II), any one of _{R 1 ~R 3, R 5 ~R} 7 is an alkoxy group or an alkyl group, claim 1 photosensitive composition. In formula (II), any one of _{R 1 ~R 3, R 5 ~R} 7 is an alkyl group of an alkoxy group or a C1-20 having 1 to 20 carbon atoms, photosensitive composition according to claim 2, wherein object. The photosensitive composition of Claim 3 whose R < ₁ > -R < ₃ >, R < ₅ > -R < ₇ > is a C4-C20 alkoxy group in general formula (II).   The photosensitivity according to any one of claims 1 to 4, wherein the sensitizing dye (B) is a dye selected from the group consisting of coumarins, styryls, cyanines, and merocyanines. Composition.   An image recording material having a photosensitive layer containing the photosensitive composition according to any one of claims 1 to 5 on a support.   The image which scan-exposes the image recording material which has a photosensitive layer containing the photosensitive composition as described in any one of Claims 1-5 on a support using a laser light source with a wavelength shorter than 450 nm. Recording method.   The image recording method according to claim 7, further comprising removing an unexposed portion with an aqueous developer solution.   A lithographic printing plate precursor having a photosensitive layer containing the photosensitive composition according to any one of claims 1 to 5 on a support.