JP2003029408A - Photosensitive composition and photosensitive planographic printing plate material utilizing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high sensitivity photosensitive composition which does not require an over layer and is hardly affected by oxygen and to provide a photosensitive composition and a photosensitive planographic printing plate having very high photosensitivity to a laser light source of a wavelength range >=750 nm. SOLUTION: The photosensitive composition contains an organic boron salt having a condensed aromatic ring having an electron donative substituent, a sensitizing dye having the absorption maximum at >=750 nm wavelength, an alkali-soluble binder and a compound having two or more ethylenic double bonds capable of radical addition in one molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative photosensitive composition having sensitivity to near infrared rays, and further to a photosensitive lithographic printing plate material using the same. More specifically, it relates to a negative photosensitive composition and a photosensitive lithographic printing plate material capable of forming an image by using a scanning exposure device such as a near infrared laser. Further, the present invention relates to a photosensitive composition suitable for forming a printed wiring board resist, a color filter, a phosphor pattern, and the like.

[0002]

2. Description of the Related Art In recent years, computer-to-plate (CTP) technology has been developed to output directly on a printing plate without outputting on film based on digital data created on a computer, and various lasers are used as output machines. Various platesetters installed and photosensitive lithographic printing plates suitable for them are being actively developed. Above all, 750 nm
In the output device using the semiconductor laser or YAG laser that emits light in the near infrared region, the output of the light source is several tens.
Since a high power laser of 0 mW to several watts class is installed, it is possible to form an image with extremely high energy. For example, Japanese Patent Application Laid-Open Nos. 6-186750, 6-199064, 7-164773 and the like have filed applications for an image recording method utilizing ablation (melt removal) of a recording layer by laser light irradiation. There was a problem that dust scattered by ablation contaminates the optical system and the intensity of laser light reaching the recording layer is gradually lowered, and rather the output machine side requested that ablation not occur.

Another image recording method using a high-power near-infrared semiconductor laser is disclosed in, for example, Japanese Patent Laid-Open No. 7-20629.
No. 7, No. 7-271029, No. 9-185160, No. 9-197671, No. 9-222731, and No. 9-2.
No. 39945, 10-142780 and the like, decomposition of a latent acid generator using heat generated by photothermal conversion in a combination of a latent acid generator and a near-infrared absorbing dye, and generation in this laser irradiation part. There is disclosed a negative type image forming method using acid-catalyzed thermal crosslinking using an acid. In these systems, in order to crosslink the binder resin by an acid-catalyzed crosslinking reaction, it is necessary to perform heat treatment at 100 to several tens of degrees using an oven or the like after laser exposure, which is a serious problem. It is necessary to uniformly perform the heat treatment conditions on the entire recording image surface.If the heat treatment is insufficient, the image may be lost during development, or if the heat treatment temperature is partially high or the heating time is long. In the case of a long period of time, the progress of development is deteriorated, and problems such as residual film remaining and poor elution occur. In practice, it is extremely difficult to perform such heat treatment uniformly, especially when the recording area is large, and there has been a strong demand for a means for avoiding the heat treatment after exposure.

What has been required of the negative type recording material in the prior art is a material which does not cause ablation, has high sensitivity and does not require a heat treatment after exposure. Regarding the increase in sensitivity, a system in which photon mode recording, which is an application of conventional high sensitivity photopolymer technology, is applied to near infrared light, not heat mode recording utilizing the photothermal conversion described above, is disclosed in, for example, JP-A-2000- 1222
74, 2000-131833, 2000-1
Nos. 81059 and 2000-194124 disclose that in a photopolymer system containing a photopolymerization initiator and an ethylenically unsaturated compound, various dyes that spectrally sensitize the photopolymerization initiator in near infrared light are used. A high-sensitivity negative recording material has been provided. However, even in these cases, as in the case of the conventional high-sensitivity photopolymer, a protective layer (overlayer) using polyvinyl alcohol or the like is formed on the photosensitive layer, and the effect of oxygen that inhibits the polymerization chain reaction is affected. Had to shut off. However, such an oxygen barrier layer absorbs moisture in a high-humidity atmosphere, easily causes blocking when recording materials are stacked, and sticks to the interleaving paper or the like inserted between recording materials or between recording materials. Therefore, it has been a cause of troubles such as double feeding of the recording material to the output machine and defective removal of the interleaf paper. Furthermore, due to the presence of the over layer, there is a problem of image quality deterioration due to light scattering during laser exposure,
In the development, there are problems that a pre-water washing step for removing the over layer is required prior to the alkali development, and that a step of further coating the over layer after coating the photosensitive layer is required in the production.

Furthermore, in the above-mentioned conventional techniques, since a polymerization chain is used, a soft image reproduction is likely to occur in the relationship between the exposure energy and the residual film rate after development, and the photosensitivity is generally softened. Therefore, especially in laser scanning exposure, the edges of fine lines and halftone dots are gently reproduced, resulting in image reproduction with insufficient contrast, and when these are used as a printing plate, the number of printed sheets can be reduced. The thin lines gradually become thinner as they are stacked,
There was a problem that net percentage decreased.

[0006]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a highly sensitive negative-working photosensitive composition which does not require an overlayer and is hardly affected by oxygen. Particularly, it is to provide a photosensitive composition and a photosensitive lithographic printing plate having a sufficiently high photosensitivity to a near infrared laser light source of 750 nm or more.

[0007]

The above object of the present invention is to provide an organic boron salt having a condensed aromatic ring having an electron donating substituent, a sensitizing dye having an absorption maximum at a wavelength of 750 nm or more, an alkali-soluble binder, and It was basically achieved by using a photosensitive composition characterized by containing a compound having two or more ethylenic double bonds capable of radical addition in the molecule.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The organic boron salt used in the present invention has three condensed aromatic rings and one alkyl group independently linked to a boron atom, and at least one of the condensed aromatic rings has an electron-donating substituent. Compounds having are preferred. More preferably, it is a compound in which each of the three condensed aromatic rings linked to a boron atom has an electron-donating substituent. The fused aromatic ring preferably does not have an electron-withdrawing substituent, but even if it has an electron-withdrawing substituent, Hammett's substituent constant σ value as a whole substituent is negative. This is very important. The general formulas of preferred compounds of the organic boron salt used in the present invention are shown below.

[0009]

[Chemical 2]

In the formula, D ₁ , D ₂ and D ₃ represent condensed aromatic rings. R ₃ , R ₄ and R ₅ each independently represent a substitutable group or atom, and p, q and r each represent 0 or an integer of 1 or more, and R ₃ , R ₄ and R ₅ At least one of
One is an electron-donating substituent. R ₆ represents an alkyl group and A ⁺ represents a cation.

In the above, the fused aromatic ring refers to a polycyclic compound in which two or more aromatic rings are integrated in a form sharing two or more atoms, and specifically, a naphthalene ring. , Anthracene ring, phenanthrene ring, pyrene ring and the like. The electron-donating substituent is a substituent having a negative substituent constant σ value when substituted at the para position in Hammett's rule, and alkyl groups, aryl groups, alkyloxy groups, alkylamino groups and the like are mentioned as preferred examples. However, any substituent may be further bonded to these.

In the above, preferably R₃, R_Four, And
And R_FiveEach of which contains an electron-donating substituent.
When p, q, and r are integers of 2 or more, R₃, R_Four, And R_Five
Are present in each case, but in this case, the substitutable group is also
The atoms may be the same or different.
R₃, R_Four, And R_FiveIf there are multiple₃，
R _Four, And R_FiveHammett of total substituents in each of
The prescribed substitution number σ value is preferably negative. In the present invention
And particularly preferably R₃, R_Four, And R_FiveAre each
This is the case where it is composed of only child-providing substituents.

Regarding the organic boron salt compound having a substituent bonded thereto, for example, JP-A-9-188686 discloses an organic boron bonded to an aromatic ring substituted with an electron-withdrawing group having a positive substituent constant σ value according to Hammett's rule. It is described that the salt compound improves the stability of the boron salt compound in a binder having an acid group, or JP-A 2000-319283 discloses that an electron-donating substituent is added to the ortho position of an aromatic ring. By having an electron-withdrawing substituent together, the overall effect of the substituent is that the σ value shows a positive value, and the sensitivity and storage stability of the electron-withdrawing organic boron salt compound are improved. The compatibility is described. Further, Japanese Patent Application Laid-Open No. 2001-75276 also describes a photosensitive composition in which an organic boron salt compound having an electron-withdrawing substituent and an infrared absorbing dye are similarly combined, but the sensitivity is low and the present invention is low. The target high sensitivity level could not be reached at all.

A common matter in the prior arts as described above is that the stability is improved by bonding an aromatic ring introduced with an electron-withdrawing group having a positive Hammett substituent constant σ value to a boron atom. Although shown, the biggest difference from the present invention is that in the present invention, an organic boron salt compound in which a fused aromatic ring having an electron donating substituent having a negative σ value is bound to a boron atom is used. Therefore, it has been found that this significantly improves the sensitivity. In addition, regarding the storage stability, it was found that when it is used in the constitution of the present invention, it exhibits extremely good stability.

As A ⁺ representing a cation in the above chemical formula 2, an alkali metal ion and an onium compound are preferably used. Particularly preferred examples are ammonium salts such as tetraalkylammonium salts, sulfonium salts such as triarylsulfonium salts, as onium salts,
Examples thereof include iodonium salts such as diaryliodonium salts and phosphonium salts such as triarylalkylphosphonium salts. Examples of particularly preferable organic boron salts relating to the present invention are shown below.

[0016]

[Chemical 3]

[0017]

[Chemical 4]

There is a preferable range for the ratio of the organic boron salt compound according to the present invention in the photosensitive layer, and it is 0.5 part by weight with respect to 100 parts by weight of all components constituting the photosensitive layer. To 50 parts by weight, and most preferably 1 to 30 parts by weight.

The photosensitive composition of the present invention has absorption in an infrared light region of 750 nm or more and spectrally sensitizes the above-mentioned organic boron salt so that it can be applied to various light sources of infrared light of 750 nm or more. It also contains a dye. Such sensitizing dyes include cyanine dyes, phthalocyanine dyes, merocyanine dyes, porphyrin dyes, polyene dyes, azo dyes, triphenylamine dyes, polymethine acridine dyes, styryl dyes, squarylium dyes. , (Thio) pyrylium dyes and the like.
Examples of preferable sensitizing dyes that can be used in the present invention are shown below, but the present invention is not limited thereto.

[0020]

[Chemical 5]

[0021]

[Chemical 6]

There is a preferable range for the ratio of the near-infrared absorbing dye spectrally sensitizing the organic boron salt compound according to the present invention in the photosensitive layer, and 100 parts by weight of all components constituting the photosensitive layer. 0.1 part by weight to 3 parts by weight
It is preferably present in the range of 0 parts by weight, and most preferably in the range of 0.1 parts by weight to 20 parts by weight.

The alkali-soluble binder used in the present invention is a binder that can be dissolved or removed in an alkaline aqueous solution, and a substituent such as a hydroxyl group, a phenolic hydroxyl group, a carboxyl group or an ammonium base is contained in the repeating unit constituting the binder. It is preferable to use a binder having the above, and most preferable is a binder having a carboxyl group.

The above-mentioned particularly preferable alkali-soluble binder having a carboxyl group is preferably various copolymer binders, which can be obtained by copolymerizing a monomer having a carboxyl group with another arbitrary copolymerizable monomer. Most preferably, it is a binder. The proportion of the carboxyl group-containing monomer in the copolymer is preferably 5% by weight or more and 99% by weight or less, and if the proportion is less than this, the copolymer may not be dissolved in the alkaline aqueous solution. As the carboxyl group-containing monomer, acrylic acid, methacrylic acid, acrylic acid 2-carboxyethyl ester, methacrylic acid 2-carboxyethyl ester, crotonic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, Examples include 4-carboxystyrene and the like.

The most preferable alkali-soluble binder in the present invention is the above-mentioned copolymer having a carboxyl group and a polymer having an ethylenic double bond capable of radical addition in the side chain. It is particularly preferred because it gives a photosensitive composition that is sensitive.
Examples of such polymers having a double bond in the side chain include, for example, JP-B-49-34041 and JP-A-6-105.
Various polymers such as those described in JP-A No. 353, JP-A 2000-187322 and the like are preferably used.
Examples of polymers preferably used in the present invention are shown below. In the formula, the numeral represents the weight% of each repeating unit in 100% by weight of the total composition of the copolymer.

[0026]

[Chemical 7]

As a more preferable example of the polymer having a double bond in the side chain as described above, the case where the double bond has a specific structure as shown in the following chemical formula 8 is particularly highly sensitive and is affected by oxygen. It is extremely preferable because it is difficult to receive and does not require an over layer for blocking oxygen.

[0028]

[Chemical 8]

In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents any substitutable atom or group other than a hydrogen atom. k represents an integer from 0 to 4.

The above-mentioned polymer having a substituent represented by the chemical formula 8 in the side chain is a polymer in which the substituent is bonded to the main chain directly or through a linking group, and the linking group is not particularly limited. Examples include any group, atom or a combination thereof. The above-mentioned polymer having a substituent represented by the chemical formula 8 in the side chain is, more specifically, a polymer having the group represented by the following chemical formula 9 in the side chain.

[0031]

[Chemical 9]

In the formula, Z ₁ represents a linking group, n ₁ represents 0 or 1, m ₁ represents an integer of 0-4, and k ₁ represents an integer of 1-4.

The chemical formula 9 will be described in more detail. As the linking group for Z ₁ , an oxygen atom, a sulfur atom, an alkylene group,
Alkenylene group, an arylene _{group, -N (R 3) -,} - C
(O) -O -, - C (R 4) = N -, - C (O) -, a sulfonyl group, a heterocyclic group, and either alone or two or more conjugated group such as a group represented by the following formula 10 Is mentioned. Here, R ₃ and R ₄ represent a hydrogen atom, an alkyl group, an aryl group, or the like. Further, the above-mentioned linking group may have a substituent such as an alkyl group, an aryl group and a halogen atom.

[0034]

[Chemical 10]

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

Preferred examples of the group represented by Chemical formula 8 are shown below, but the group is not limited to these examples.

[0037]

[Chemical 11]

[0038]

[Chemical 12]

[0039]

[Chemical 13]

The linking group in the above chemical formula 9 is preferably one containing a heterocycle, and k ₁ is preferably 1 or 2.

The polymer having a double bond as shown in the above various examples is preferably soluble in an alkaline aqueous solution, and for this reason, it is a polymer containing a carboxyl group-containing monomer as a copolymerization component. Particularly preferred. In this case, as the ratio of double bonds in the copolymer composition, the ratio of the group having a double bond as shown in Chemical formula 8 in 100% by weight of the total composition is 1% by weight or more and 95% by weight or less. Is preferable, and the effect of the introduction may not be recognized at a ratio less than this. Further, when the content is 95% by weight or more, the copolymer may not be dissolved in the alkaline aqueous solution. Further, the proportion of the carboxyl group-containing monomer in the copolymer is also preferably 5% by weight or more and 99% by weight or less, and if the proportion is less than this, the copolymer may not be dissolved in the alkaline aqueous solution.

Examples of the above-mentioned carboxyl group-containing monomer include acrylic acid, methacrylic acid, acrylic acid 2-carboxyethyl ester, and methacrylic acid 2 as described above.
Examples include carboxyethyl ester, crotonic acid, maleic acid, fumaric acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, 4-carboxystyrene and the like.

In addition to the monomer having a carboxyl group, it is also preferable to introduce another monomer component into the copolymer to synthesize and use it as a multicomponent copolymer. In such cases, the monomers that can be incorporated into the copolymer include styrene, 4-methylstyrene, and 4-methylstyrene.
Styrene derivatives such as hydroxystyrene, 4-acetoxystyrene, 4-carboxystyrene, 4-aminostyrene, chloromethylstyrene and 4-methoxystyrene,
Methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate and other alkyl methacrylates, phenyl methacrylate, benzyl methacrylate and other methacrylate aryl esters. Alternatively, methacrylic acid having an alkyleneoxy group such as alkylaryl esters, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methoxydiethylene glycol monoester of methacrylic acid, methoxypolyethylene glycol monoester of methacrylic acid, polypropylene glycol monoester of methacrylic acid. Such as esters, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, etc. Examples similar to those corresponding methacrylic acid esters as mino group-containing methacrylic acid esters or acrylic acid esters, or vinylphosphonic acid as a monomer having a phosphoric acid group, or amino group-containing monomers such as allylamine and diallylamine Alternatively, sulfonic acid groups such as vinyl sulfonic acid and its salt, allyl sulfonic acid and its salt, methallyl sulfonic acid and its salt, styrene sulfonic acid and its salt, 2-acrylamido-2-methylpropane sulfonic acid and its salt. Having monomers, 4-vinylpyridine, 2-vinylpyridine, N-vinylimidazole, N
-Monomers having a nitrogen-containing heterocycle such as vinylcarbazole, or 4-vinylbenzyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, dimethylaminopropylacrylamide as a monomer having a quaternary ammonium base. Quaternary compound with methyl chloride, quaternary compound with N-vinylimidazole methyl chloride,
4-vinylbenzylpyridinium chloride, etc., or acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, dimethylacrylamide,
Diethyl acrylamide, N-isopropyl acrylamide, diacetone acrylamide, N-methylol acrylamide, N-methoxyethyl acrylamide, 4-
Acrylamide or methacrylamide derivative such as hydroxyphenylacrylamide, and further vinyl such as acrylonitrile, methacrylonitrile, phenylmaleimide, hydroxyphenylmaleimide, vinyl acetate, vinyl chloroacetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, etc. Esters, vinyl ethers such as methyl vinyl ether and butyl vinyl ether, and various monomers such as N-vinylpyrrolidone, acryloylmorpholine, tetrahydrofurfuryl methacrylate, vinyl chloride, vinylidene chloride, allyl alcohol, vinyltrimethoxysilane, and glycidyl methacrylate are appropriately used. It can be used as a copolymerization monomer. As the proportion of these monomers in the copolymer, the preferable proportions of the group having a double bond and the carboxyl group-containing monomer as shown in the chemical formula 8 in the above-mentioned copolymer composition are kept. It can be introduced at any ratio as long as it is present.

There is a preferable range for the molecular weight of the above-mentioned polymer, and the weight average molecular weight is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 10,000 to 300,000.

There is a preferable range for the ratio of the polymer of the present invention in the photosensitive layer, and it is in the range of 10 to 80 parts by weight with respect to 100 parts by weight of all components constituting the photosensitive layer. Is more preferable, and the case where it is contained in the range of 20 to 80 parts by weight is most preferable.

Examples of the polymer having the group represented by Chemical formula 8 according to the present invention are shown below. In the formula, the numeral represents the weight% of each repeating unit in 100% by weight of the total composition of the copolymer.

[0047]

[Chemical 14]

[0048]

[Chemical 15]

[0049]

[Chemical 16]

[0050]

[Chemical 17]

[0051]

[Chemical 18]

The present invention contains a compound having two or more ethylenic double bonds capable of radical addition in the molecule together with the above-mentioned polymer. Examples of preferable compounds include 1,4-butanediol diacrylate and 1,6-
Hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trisacryloyloxyethyl isocyanurate, tripropylene glycol diacrylate, ethylene glycol glycerol triacrylate, glycerol epoxy triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate Polyfunctional acrylic monomers such as acrylate and pentaerythritol tetraacrylate, or polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, etc., are also used as various polymers with acryloyl group and methacryloyl group introduced. To be done.

An acrylate compound as described above,
There is a preferable range for the ratio of the polymer of the present invention, and it is preferable that the acrylate compound is contained in the range of 1 part by weight to 100 parts by weight, and further 5 parts by weight to 100 parts by weight with respect to 1 part by weight of the polymer. It is preferably contained in the range of parts by weight.

As a more preferred example of the compound having two or more ethylenic double bonds capable of radical addition in the molecule, a low molecular weight compound having two or more substituents represented by the chemical formula 8 in the molecule (hereinafter referred to as the present invention The above-mentioned monomer is referred to as a monomer and the molecular weight is several thousand or less). When the monomer of the present invention is used in combination with the polymer of the present invention, the radicals generated by photodecomposition of the organic boron salt compound are effectively crosslinked by recombination of styryl radicals generated by addition. Therefore, a high-sensitivity negative photosensitive material can be prepared. The monomer of the present invention is typically represented by the following general formula.

[0055]

[Chemical 19]

In the formula, Z ₂ represents a linking group. R ₇ represents a hydrogen atom or a methyl group. R ₈ represents a substitutable group or atom. k ₂ represents an integer of 2 or more, and m ₂ represents an integer of 0-4.

The chemical formula 19 will be described in more detail. Z ₂
As the linking group of, an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group, an arylene group, —N (R ₅ ) —,
-C (O) -O -, - C (R 6) = N -, - C (O)
-, A sulfonyl group, a heterocyclic group and the like, or a group in which two or more are compounded. Here, R ₅ and R ₆ represent a hydrogen atom, an alkyl group, an aryl group or the like. Further, the above-mentioned linking group may have a substituent such as an alkyl group, an aryl group and a halogen atom.

Examples of the heterocyclic group include a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, a tetrazole ring, an isoxazole ring, an oxazole ring, an oxadiazole ring, an isothiazole ring, a thiazole ring, a thiadiazole ring, and a thiatriazole ring. , Indole ring, indazole ring, benzimidazole ring, benzotriazole ring, benzoxazole ring, benzthiazole ring,
Examples include nitrogen-containing heterocycles such as benzselenazole ring, benzothiadiazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, quinoxaline ring, furan ring, and thiophene ring. The group may be bonded.

Among the compounds represented by the above chemical formula 19, there are preferable compounds. Preferred specific examples of the compound represented by Chemical formula 19 are shown below, but the invention is not limited to these examples.

[0060]

[Chemical 20]

[0061]

[Chemical 21]

[0062]

[Chemical formula 22]

The amount of the above-mentioned monomer of the present invention added is 1 part by weight to 200 parts by weight per 100 parts by weight of the polymer of the present invention.
The content is preferably in the range of 5 parts by weight, and more preferably in the range of 5 parts by weight to 100 parts by weight. Furthermore, in addition to the monomer of the present invention, it is also preferable to use the above-mentioned various acrylate compounds in combination. In this case, the ratio of the monomer of the present invention to the acrylate compound is preferably in the range of 1: 0 to 1:10.

In addition to the above-mentioned organic boron salt compound relating to the present invention, other known photopolymerization initiators may be used in combination in some cases to provide a photosensitive composition having improved sensitivity. Examples of other photopolymerization initiators that can be used for these purposes include (a) aromatic ketones,
(B) aromatic onium salt compound, (c) organic peroxide,
(D) hexaarylbiimidazole compound, (e) ketoxime ester compound, (f) azinium compound,
Examples include (g) active ester compounds and (h) trihaloalkyl-substituted compounds.

In the present invention, as the photopolymerization initiator which is preferably used in combination with the organic boron salt compound in the above-mentioned examples, a trihaloalkyl-substituted compound is particularly mentioned. The trihaloalkyl-substituted compound is specifically a compound having at least one trihaloalkyl group such as trichloromethyl group or tribromomethyl group in the molecule, and a preferable example thereof is a nitrogen-containing heterocycle. Examples of the compound bonded to the group include s-triazine derivatives and oxadiazole derivatives, or
Examples thereof include trihaloalkylsulfonyl compounds in which the trihaloalkyl group is bonded to an aromatic ring or a nitrogen-containing heterocycle via a sulfonyl group.

Particularly preferable examples of the trihaloalkyl-substituted nitrogen-containing heterocyclic compound and the trihaloalkylsulfonyl compound are shown in Chemical formulas 22 and 23.

[0067]

[Chemical formula 23]

[0068]

[Chemical formula 24]

When the above-mentioned trihaloalkyl-substituted compound is used together with the organic boron salt compound, there is a preferable range for the ratio in the former photosensitive layer, and 100 parts by weight of all components constituting the photosensitive layer. Against
It is preferably present in the range of 0.5 to 50 parts by weight, and most preferably 1 to 30 parts by weight.

As the most preferable system, the polymer of the present invention and the monomer of the present invention are used in combination with the organoboron compound to compare with the conventional system of a conventional binder and a polyfunctional acrylate compound. Then, the sensitivity is drastically improved because photo-curing occurs extremely efficiently because it is less susceptible to sensitivity deterioration due to the polymerization inhibitor added to improve storage stability and less susceptible to oxygen inhibition. It can be mentioned.

When conventional radical photopolymerization is used, it is necessary to provide a resin such as polyvinyl alcohol, which is easily affected by oxygen in the atmosphere and has an oxygen barrier property, on the surface of the photosensitive layer as an overlayer. I got angry. Further, in order to accelerate or complete the polymerization after exposure, 100
It was necessary to perform heat treatment at a temperature of around ℃ for several minutes.

On the other hand, when the polymer of the present invention and the monomer of the present invention are used in combination, a system which is sufficiently photocured without providing the overlayer as described above is provided,
In addition, it is characterized in that it is not necessary to perform heat treatment after exposure, and by using a combination of a near-infrared absorbing dye and an organic boron salt compound or a sensitizer such as a trihaloalkyl-substituted compound, a high-sensitivity photosensitizer can be obtained. The feature is that a sexual composition is obtained. In addition, the photosensitive composition of the present invention is characterized by having extremely small latent image regression.

An important point as one of the effects of the present invention is that it gives a hard image reproduction as a photosensitive property, and that it can be particularly preferably used as a photosensitive composition for laser scanning exposure. Especially when a near infrared laser emitting at 750 nm or more is used as a light source,
Since the edge portion of the image is sharply reproduced and high resolution image quality is provided, it can be used very preferably.

Further, in terms of sensitivity storage stability of the photoconductor, the use of the polymer and the monomer of the present invention improves the compatibility of the organic boron salt compound and reduces the diffusion of each component in the photoconductor. It is presumed that this is due to the high glass transition temperature of the matrix, but one of the characteristics is that it exhibits stable sensitivity even during storage under high temperature and high humidity.

The photosensitive composition of the present invention may preferably be added with other components for various purposes in addition to the components described above. In particular, it is preferable to add various polymerization inhibitors for the purpose of preventing thermal polymerization or thermal crosslinking of styryl groups and improving long-term storage stability. In this case, as the polymerization inhibitor, compounds having various phenolic hydroxyl groups such as hydroquinones, catechols, naphthols and cresols, quinone compounds, N-nitrosophenylhydroxylamine salts and the like are preferably used. In this case, the amount of the polymerization inhibitor added is preferably 0.1 part by weight to 10 parts by weight with respect to 100 parts by weight of the polymer.

In addition to the components of the photosensitive composition, various dyes and pigments are added for the purpose of enhancing the visibility of images, and inorganic fine particles or fine particles are used for the purpose of preventing blocking of the photosensitive composition. It is also preferable to add organic fine particles.

With respect to the thickness of the photosensitive layer itself when it is used as a lithographic printing plate material, it is preferable that the photosensitive layer is formed on the support to have a dry thickness in the range of from 0.5 to 10 μm, and further from 1 to 5 μm. The range is extremely preferable because the printing durability is significantly improved.
The photosensitive layer is prepared by preparing a solution in which the above-mentioned three elements are mixed, is coated on the support by various known coating methods, and is dried. As the support, for example, a film or polyethylene-coated paper may be used, but a more preferred support is an aluminum plate which is polished and has an anodized film.

In order to use the material having the photosensitive layer formed on the support as described above as a printing plate, it is subjected to contact exposure or laser scanning exposure, and the exposed portion is crosslinked. Since the solubility in the alkaline developing solution is lowered, the pattern formation is performed by eluting the unexposed area with the alkaline developing solution described later.

The alkaline developing solution is not particularly limited as long as it is a solution capable of dissolving the polymer of the present invention, but preferably sodium hydroxide, potassium hydroxide, sodium silicate, potassium silicate, sodium metasilicate, meta. An aqueous developer containing an alkaline compound such as potassium silicate, monoethanolamine, diethanolamine, triethanolamine, or triethylammonium hydroxide satisfactorily dissolves unexposed areas selectively and exposes the underlying support surface. It is extremely preferable because it can be done. Furthermore, it is also preferable to add various alcohols such as ethanol, propanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin and benzyl alcohol to the alkaline developer. After the development processing is carried out using such an alkaline developer, gum arabic or the like is preferably used for usual gumming.

[0080]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples in addition to the effects.

Examples 1 to 4 and Comparative Examples 1 to 4 A graining anodized aluminum plate having a thickness of 0.24 mm was used, and a photosensitive coating solution having the following formulation was prepared thereon. Was applied to give a dry thickness of 2.0 μm, and dried in a dryer at 75 ° C. for 6 minutes. <Photosensitive coating liquid> 12 parts by weight of the polymer of the present invention (P-1) Organoboron salt compound (Table 1) 1 part by weight Trihaloalkyl-substituted compound (T-4) 0.7 parts by weight Near infrared absorbing dye (Table 1) 0.3 parts by weight 10% phthalocyanine dispersion (colorant) 0.6 parts by weight Dioxane 70 parts by weight Cyclohexanone 20 parts by weight

[0082]

[Table 1]

[0083]

[Chemical 25]

The obtained light-sensitive material was exposed as follows. That is, using a halogen lamp with a color temperature of 3100K as a light source, the light amount is adjusted so that the amount of light that passes through an optical filter that cuts light having a wavelength of 780 nm or less becomes ² mW / cm ^2, and a step wedge with a density difference of 0.15 intervals Control wedge (made by Fuji Photo Film)
Was exposed for 10 seconds. After the exposure, development was performed with an alkaline developer containing 1% by weight of potassium silicate, 2% by weight of potassium hydroxide, and 0.1% by weight of a nonionic surfactant. After the development processing, in the pattern of the step wedge formed on the aluminum plate, the maximum number of steps (S1) remaining as an image and the number of steps (S2) until the image density reaches the saturation value were obtained as the sensitivity. The larger these numbers are, the higher the sensitivity is,
The smaller the difference between the two values, the harder the tone reproducibility. The results are summarized in Table 3. In Comparative Example 3, a clear image was not formed. In Comparative Examples 1 and 2, an image was formed, but the reflection density of the remaining image was much lower than that before development, and the value of S2 reaching the saturation density was not obtained, but the gradation was soft. there were. In Comparative Example 4, relatively high sensitivity was obtained, but in comparison with the Example, the sensitivity was low and the tone was slightly soft.

[0085]

[Table 2]

Examples 5 to 7 Using the samples prepared in Examples 1 to 3 above, a wavelength of 830
Using a semiconductor laser (output: 1 W) of nm, the laser spot diameter was adjusted to 20 μm using an external drum type scanning exposure device, and scanning exposure was performed by changing the plate surface power. Development was carried out in the same manner as in the previous example, and the minimum plate surface energy at which an image was formed after development was determined, and the results shown in the table below were obtained.

[0087]

[Table 3]

Examples 8 and 9 and Comparative Example 9 A photosensitive coating solution having the following formulation was prepared, and an anodized aluminum base coil (thickness 0.24 mm) was used in a gravure coater to give a width of 400 mm. Length 200
Application was carried out over m. The length of the drying zone was 10 m, and the drying temperature was set to 70 ° C. Coating speed is 10m
Per minute. The coating amount is a measured value in the dry coating amount 2.
It was 4 g / m ² . <Photosensitive coating liquid> Polymer (P-1) of the present invention 11 parts by weight Monomer (C-1) of the present invention 4 parts by weight Organoboron salt compound (Table 4) 1.2 parts by weight Trihaloalkyl-substituted compound ( T-2) 0.6 parts by weight Near infrared absorption dye (Table 1) 0.4 parts by weight 10% phthalocyanine dispersion (colorant) 0.5 parts by weight Dioxane 70 parts by weight Cyclohexanone 20 parts by weight

[0089]

[Table 4]

400 m of the sample prepared as described above
PT-R4000 manufactured by Dainippon Screen Mfg. Co., Ltd. as a platesetter after being cut into a size of mx 560 mm.
Exposure was carried out using a (830 nm LD mounted). As the exposure conditions, the drum rotation speed was 1000 rpm, and the exposure energy was 10 mJ / cm ² in Examples 8 and 9.
In Comparative Example 9, the exposure was performed so as to be 70 mJ / cm ² . The exposed plate is the automatic developing device for PS plate PD-9.
12-M (manufactured by Dainippon Screen Mfg. Co., Ltd.) was used to perform development using the developer used in the previous example. In each case, the image on the plate clearly reproduced a 20-micron fine line, and even when observed by a scanning electron microscope, the edge portion of the image line was sharp and showed a sharp image line profile. In order to perform this ordinary offset printing, Ryobi-560 was used as the printing machine, F gloss black B manufactured by Dainippon Ink and Chemicals was used as the printing ink, and the commercially available dampening solution was diluted. I used it. As a print evaluation item, the ink is applied by the number of prints until the ink density transferred from the beginning of printing to the paper is sufficient and stabilized,
The smaller this number, the better. The printing durability was evaluated based on the number of printed sheets until the start of the loss of fine halftone dots and fine lines in the test image. The presence / absence of background stain was visually determined by the presence / absence of background stain on the printed matter. As a result, when the photosensitive lithographic printing plates prepared in Examples 8 and 9 were used, ink coverage was good at 5 sheets or less, and printing durability was good even when printing 200,000 sheets. was gotten. In addition, good results were obtained without the occurrence of scumming. On the other hand, in the printing plate obtained in Comparative Example 9, the number of ink-carrying sheets was 20, and the printing durability was 70,000, which was an inferior result. In all of the examples, when the sample was stored in an atmosphere of 50 ° C. and 80% relative humidity for 2 weeks and then exposed and developed in the same manner, no change was observed in sensitivity and developability, which was good. It showed excellent storage stability.

[0091]

EFFECTS OF THE INVENTION According to the present invention, a highly sensitive photosensitive composition which does not require an overlayer and is hardly affected by oxygen can be obtained. In particular, a photosensitive composition and a photosensitive lithographic printing plate having extremely high photosensitivity to a laser light source having a wavelength range of 750 nm or more can be obtained.

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Claims (7)

[Claims] 1. An organic boron salt having a condensed aromatic ring having an electron-donating substituent, a sensitizing dye having an absorption maximum at a wavelength of 750 nm or more, an alkali-soluble binder, and an ethylenic double bond capable of radical addition in the molecule. A photosensitive composition comprising a compound having two or more bonds. 2. The alkali-soluble binder,
It has an ethylenic double bond capable of radical addition to the side chain,
The photosensitive composition according to claim 1, which is a polymer having a carboxyl group. 3. The photosensitive composition according to claim 1, wherein the binder is a polymer having a substituent represented by Chemical formula 1 in a side chain and a carboxyl group. [Chemical 1] In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents any substitutable atom or group. k represents an integer from 0 to 4. 4. The compound having two or more ethylenic double bonds capable of radical addition in the molecule according to claim 1, which is a low-molecular compound having two or more substituents represented by the formula 1 in the molecule. The photosensitive composition according to claim 1. 5. The photosensitive composition according to claim 1, which further comprises a haloalkyl-substituted compound. 6. The photosensitive composition according to claim 1, which is for a near infrared semiconductor laser emitting at 750 nm or more. 7. A photosensitive lithographic printing plate material comprising the photosensitive composition according to claim 1.