JP2002023364A - Positive photosensitive composition and positive photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive type photosensitive composition insensitive to light in the UV region, excellent in sensitivity, chemical resistance and contrast between image and non-image areas as well as in handleability under a white fluorescent lamp and in the residual film retaining ratio of the image area and to provide a positive type photosensitive planographic printing plate. SOLUTION: The positive type photosensitive composition contains (A) a novolak resin, (B) a polyvinyl ester resin and (C) a photothermal conversion material. The positive type photosensitive planographic printing plate is obtained by applying the composition to a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to photosensitive lithographic printing plates, proofs for simple proof printing, copper etching resists for wiring boards and gravure, resists for color filters used in flat display manufacturing, photoresists for LSI manufacturing, etc. The positive photosensitive composition and the positive photosensitive lithographic printing plate which are used, which are mainly sensitive to light in the near infrared region, are particularly suitable for direct plate making using a semiconductor laser or a YAG laser. The present invention relates to a composition and a positive photosensitive lithographic printing plate.

[0002]

2. Description of the Related Art Conventionally, as a positive photosensitive composition, for example, an o-quinonediazide group-containing compound which forms indenecarboxylic acid upon irradiation with light and becomes alkali-soluble,
An organic polymer substance having an o-nitrobenzyl ester group, or a composition of a compound that generates an acid by light (photoacid generator) and a compound that is hydrolyzed by an acid and becomes alkali-soluble, There are known compositions containing a specific polymer compound (JP-B-46-27919).

On the other hand, with the advance of computer image processing technology, photosensitive or heat-sensitive direct plate making in which a resist image is directly formed by laser light or a thermal head without outputting digital image information to a silver halide mask film. The system is drawing attention. In particular, the realization of a high-resolution laser-sensitive direct plate making system using a high-output semiconductor laser or YAG laser is strongly desired in terms of miniaturization, environmental light during plate making work, and plate material cost. I have.

[0004] In recent years, as an image forming method utilizing laser exposure or heat sensitivity, a technique in which a chemically amplified photoresist is combined with a long-wavelength light-absorbing dye has been scattered.
JP-A-6-43633 discloses an image forming material containing a specific squarylium dye, a photoacid generator and a binder, and JP-A-7-20629 discloses an infrared absorbing dye, a latent Brönstedt. An image forming material containing an acid, a resol resin, and a novolak resin is disclosed in
Japanese Patent Application Laid-Open No. 271029/1995 discloses an image forming material using an s-triazine-based compound in place of the latent Bronsted acid. Further, Japanese Patent Application Laid-Open No. 7-285275 discloses a binder and Disclosed are respective imaging materials that include a substance that evolves and a substance that is thermally decomposable and substantially degrades the solubility of the binder when not decomposed.

Further, these conventional techniques are sensitive to light in the ultraviolet region, and the reaction proceeds during handling under a white fluorescent lamp, so that it is difficult to obtain stable quality. In contrast, Japanese Patent Application Laid-Open No. 9-438
No. 47 discloses a positive composition containing a resin which is hardly soluble in an alkali developing solution and an infrared absorbing agent, which is heated by infrared irradiation or the like to change crystallinity and becomes alkali-soluble, but does not change by ultraviolet irradiation. Things are also WO97 / 39
No. 894, a heat-sensitive positive type composition containing an aqueous developable polymer and a compound which inhibits the aqueous developability of the polymer, the aqueous developability of which is improved by heating but which is not changed by ultraviolet irradiation. Each is disclosed.

[0006] JP-A-9-43847 and W
The positive composition disclosed in O97 / 39894 contains a compound which undergoes a chemical change upon exposure, and causes a difference in solubility between exposed and unexposed areas due to the chemical change. Unlike products, they cause differences in solubility due to changes other than chemical changes, and they do not contain compounds that are sensitive to light in the ultraviolet region. Have.

[0007] However, according to the study of the present inventors,
The above-mentioned conventional technique has a disadvantage that an image obtained by a negative photosensitive composition which requires heat treatment after exposure is not always stable under the processing conditions. Further, in a positive photosensitive composition which does not require heat treatment after exposure, sensitivity and contrast between an image area (non-exposed area) and a non-image area (exposed area) are insufficient. There are problems such as insufficient removal of the image area and insufficient retention of the residual film ratio in the image area.Particularly, changes other than chemical changes may cause differences in solubility between exposed and unexposed areas. JP-A-9-43847 and WO
In the positive composition disclosed in Japanese Patent Application No. 97/39894, the tendency was found to be remarkable.

On the other hand, the applicant of the present application does not contain a compound sensitive to light in the ultraviolet region, and cannot expect a photochemical change of a photothermal conversion material and an alkali-soluble resin for light in the near infrared region. With such a system, it has been found that a photosensitive composition capable of forming a positive image which also solves the above-mentioned problems can be obtained (Japanese Patent Application Laid-Open No. 10-268512).

Japanese Patent Application Laid-Open No. 10-268512 discloses that
Novolak resins and copolymers of acrylic acid derivatives are disclosed as alkali-soluble resins, but specific examples only use novolak resins.
Japanese Patent Application Laid-Open No. 10-282463 discloses that a positive photosensitive composition containing a light-to-heat conversion material and an alkali-soluble resin further contains an organic acid, thereby improving the residual film ratio of an unexposed portion. Although an example in which polyacrylic acid is used in combination with a novolak resin as an organic acid is shown, further improvement in the residual film ratio is desired in view of further increasing the sensitivity of the photosensitive layer.

On the other hand, Japanese Patent Application Laid-Open No. 11-44956 discloses a substance that absorbs light and generates heat, and a specific resin such as an alkali aqueous solution-soluble resin having a phenolic hydroxyl group, a sulfonamide group, and a phenolic hydroxyl group-containing acrylamide. 50:50 to 5: 9 with a copolymer containing a copolymer component.
It is described that the positive photosensitive composition for an infrared laser included in the range of 5 improves the image intensity and the development latitude, and a certain acrylic copolymer containing a novolak resin and acrylamide as a copolymer component. However, there is also an example of the combined use, but the sensitivity and the residual film ratio are still insufficient.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and is insensitive to light in the ultraviolet region, has excellent handleability under a white fluorescent lamp, and An object of the present invention is to provide a positive photosensitive composition and a positive photosensitive lithographic printing plate which are excellent in sensitivity, chemical resistance, contrast between an image area and a non-image area, and which sufficiently retain a residual film ratio of an image area. Aim.

[0012]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that a positive photosensitive composition containing a polyvinyl ester resin with respect to a novolak resin, and that a positive photosensitive composition is provided on a support. The inventors have found that the above-mentioned object is achieved by the provided positive photosensitive lithographic printing plate, and have completed the present invention. That is, the present invention provides (A) a novolak resin, (B) a polyvinyl ester-based resin, and (C)
The gist is a positive photosensitive composition containing a light-to-heat conversion material and a photosensitive lithographic printing plate having a layer comprising the positive photosensitive composition on a support.

[0013]

First, the novolak resin as the component (A) in the positive photosensitive composition of the present invention is commonly used as a phenolic hydroxyl group-containing alkali-soluble resin in the binder resin of this kind of photosensitive composition. Such as phenol, o-cresol, m-cresol, p-cresol, 2,5-xylenol,
3,5-xylenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, propylphenol, n-butylphenol, tert-butylphenol, 1-naphthol, 2-naphthol, pyrocatechol, resorcinol, hydroquinone, pyrogallol, Phenols such as 2,2,4-benzenetriol, phloroglucinol, 4,4'-biphenyldiol, and 2,2-bis (4'-hydroxyphenyl) propane are reacted with an acidic catalyst, for example, formaldehyde. , Acetaldehyde, propionaldehyde,
Aldehydes such as benzaldehyde and furfural (paraformaldehyde may be used instead of formaldehyde and paraaldehyde may be used instead of acetaldehyde), or acetone, methyl ethyl ketone,
At least one of ketones such as methyl isobutyl ketone;
A resin polycondensed with a seed, and in the present invention, phenols as phenols, o-cresol, m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol, resorcinol And a polycondensate of formaldehyde, acetaldehyde, and propionaldehyde as aldehydes or ketones, particularly m-cresol: p-cresol:
The mixing ratio of 2,5-xylenol: 3,5-xylenol: resorcinol is 40 to 100: 0 to 5 in molar ratio.
A mixed phenol of 0: 0 to 20: 0 to 20: 0 to 20 or a mixing ratio of phenol: m-cresol: p-cresol is 1 to 100: 0 to 70: 0 to 6 in a molar ratio.
A polycondensate of 0 mixed phenols and formaldehyde is preferred. In addition, it is preferable that the positive photosensitive composition of the present invention contains a solvent inhibitor described below. The mixing ratio is 70 to 100: 0 to 30: 0 to 20: 0 in molar ratio.
The mixed phenols having a molar ratio of phenol: m-cresol: p-cresol of from 10 to 20: 0 to 60: 0 to 40:20 to 20:20 and the weight of formaldehyde Condensates are preferred.

The novolak resin has a weight average molecular weight in terms of polystyrene determined by gel permeation chromatography (hereinafter simply referred to as weight average molecular weight).
But preferably from 1,500 to 20,000, more preferably from 2,000 to 15,000, particularly preferably from 3.0 to 20,000.
Those having a size of from 00 to 12,000 are used. If the weight average molecular weight is smaller than the above range, a sufficient coating film as a resist cannot be obtained.If the weight average molecular weight is larger than the above range, the solubility in an alkali developing solution is reduced, and the removal of a non-image portion is insufficient. It tends to be difficult to obtain a resist pattern.

Next, the (B) polyvinyl ester resin which is the second essential component of the composition of the present invention will be described. The polyvinyl ester resin is a vinyl ester, that is,
Chemical structure means a polymer or copolymer of a compound having an ester bond between vinyl alcohol and an acid (vinyl ester). The acids include sulfonic acids and phosphonic acids, but preferred are carboxylic acids, that is, aliphatic carboxylic acids, aromatic carboxylic acids, and carboxylic acids containing an aromatic ring. Therefore, as the polyvinyl ester resin, a polyvinyl carboxylic acid ester resin which is a polymer or a copolymer of vinyl carboxylic acid which is an ester of vinyl alcohol and carboxylic acids is preferable. To specifically illustrate carboxylic acids,
Examples of the aliphatic carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, caproic acid, caprylic acid, chloroacetic acid, lauric acid, stearic acid, crotonic acid, and oleic acid. Examples of the aromatic or carboxylic acid containing an aromatic ring include, for example, benzoic acid, 4-tert
-Butylbenzoic acid, cinnamic acid and the like.

As the polyvinyl ester resin of the present invention, a resin derived from one or more of these vinyl esters of carboxylic acids can be used alone, or two or more of these resins can be used in combination. You can also. Among the above-mentioned vinyl esters, vinyl acetate is advantageous in view of the properties of the polymer, ease of preparation, cost, and the like. As the polyvinyl ester resin of the component (B), vinyl acetate is preferred. Polyvinyl acetate resin which is a polymer or copolymer of the above is preferred.

The vinyl ester is also extremely effective as a homopolymer, but when used as a copolymer of a vinyl ester and another monomer, physical properties different from those of the homopolymer, for example, developing property, Change properties such as chemical resistance and printing durability,
It is useful because it can be modified. Preferred examples of the monomer include (meth) acrylic acid ester, (meth) acrylic acid, acrylonitrile, styrene, maleic anhydride, aleamide, acrylamide, N-vinylpyrrolidone, ethylene and chloroethylene.
When a vinyl copolymer is prepared using these monomers, the copolymerization ratio of monomers other than the vinyl ester in the copolymer is preferably less than 50 mol%. This is because when the content is 50 mol% or more, the effect of using a vinyl ester is generally insufficient.

Among the above, when the component (B) is polyvinyl acetate, the residual film ratio is favorable and preferable. Incidentally, the weight average molecular weight in terms of polystyrene measured by GPC of the polyvinyl ester resin used in the present invention is not particularly limited,
It is preferably in the range of 5,000 to 5,000,000, more preferably 10,000 to 300,000, and particularly preferably 10,000 to 200,000. If the molecular weight is too small, the physical properties of the film are inferior. If the molecular weight is too large, the developing property tends to be disadvantageous.

The mixing ratio of the (A) novolak resin and the (B) polyvinyl ester resin of the present application is not particularly limited, but preferably the novolak resin is 99 to 65 in weight ratio.
%, And the polyvinyl ester resin is used in the range of 1 to 35%. If the blending ratio of the polyvinyl ester resin is too small, the effect of improving the residual film ratio is not sufficiently recognized. If the blending ratio is too large, there is a tendency that the developability is reduced and the exposed portion is poorly removed. More preferably, the weight ratio of the novolak resin is 98 to 70%, and the weight of the polyvinyl ester resin is 2 to 70%.
30% More preferably, the former is 95 to 70%, and the latter is 5 to
Used in the range of 30%.

The photosensitive composition of the present invention may contain an alkali-soluble resin other than the novolak resin and the polyvinyl ester resin of the present invention as long as the performance of the present invention is not impaired. Next, the component (C) in the positive photosensitive composition of the present invention will be described. The photothermal conversion material is not particularly limited as long as it is a compound capable of converting absorbed light into heat, and an organic or inorganic pigment having an absorption band in a part or all of a near infrared region of a wavelength range of 650 to 1300 nm or Among the dyes, organic dyes, metals, metal oxides, metal carbides, metal borides, etc., the light absorbing dyes are particularly effective. These light-absorbing dyes efficiently absorb light in the above-mentioned wavelength region, but hardly absorb light in the ultraviolet region, or do not substantially respond to absorption, and are weakly sensitive to ultraviolet light contained in white lamps. Is a compound having no action of modifying the photosensitive composition.

These light absorbing dyes include a nitrogen atom,
Representative examples include so-called cyanine-based dyes in which a heterocyclic ring containing an oxygen atom, a sulfur atom, or the like is bonded by polymethine (-CH =) _n , and specifically, for example, quinoline-based ( So-called cyanine in a narrow sense, indole (so-called indocyanine), benzothiazole (so-called thiocyanine), oxazole (so-called oxacyanine), aminobenzene (so-called polymethine), pyrylium-based , Thiapyrylium, squarylium, croconium, azurenium, aminium, immonium, phthalocyanine, anthraquinone, etc., among which quinoline, indole, benzothiazole, aminobenzene, pyrylium,
Alternatively, a thiapyrylium-based, aminium-based, or immonium-based dye is preferable.

In the present invention, among the cyanine-based dyes, quinoline-based dyes are preferably represented by the following general formula (I)
Those represented by a), (Ib) or (Ic) are preferred.

[0023]

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[In the formulas (Ia), (Ib) and (Ic), R ¹ and R
² each independently has an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a group which has a substituent. L ¹ represents a tri, penta or heptamethine group which may have a substituent, and two substituents on the penta or heptamethine group are connected to each other to have 5 to 5 carbon atoms. 7 may form a cycloalkene ring, and the quinoline ring may have a substituent, in which case, two adjacent substituents may be connected to each other to form a fused benzene ring. . X ^- is a counter anion. ]

Here, R in formulas (Ia), (Ib) and (Ic)¹
And R^TwoAs the substituent in the above, an alkoxy group,
A nonoxy group, a hydroxy group, or a phenyl group;
And L ¹Examples of the substituent for are an alkyl group and an amino
Group, or a halogen atom, etc., in the quinoline ring.
Alkyl, alkoxy, nitro
And a halogen atom and the like.

The indole, benzothiazole and benzoxazole dyes are particularly preferably those represented by the following formula (II).

[0027]

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[In the formula (II), Y ¹ and Y ² each independently represent a dialkylmethylene group, a sulfur atom or an oxygen atom, and R ³ and R ⁴ each independently have a substituent. An alkyl group which may be substituted, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a phenyl group which may have a substituent, and L ² represents a substituent A tri-, penta-, or heptamethine group which may have, and two substituents on the penta or heptamethine group may be linked to each other to form a cycloalkene ring having 5 to 7 carbon atoms; The condensed benzene ring may have a substituent, and in this case, two adjacent substituents may be connected to each other to form a condensed benzene ring. X ^- is a counter anion. ]

Here, examples of the substituent for R ³ and R ⁴ in the formula (II) include an alkoxy group, a phenoxy group, a hydroxy group and a phenyl group. The substituent for L ² is an alkyl group , An amino group, or a halogen atom.Examples of the substituent on the benzene ring include:
Examples thereof include an alkyl group, an alkoxy group, a nitro group, and a halogen atom.

As the aminobenzene-based dye, those represented by the following general formula (III) are particularly preferred.

[0031]

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[In the formula (III), R ⁵ , R ⁶ , R ⁷ and R
⁸ each independently represents an alkyl group; R ⁹ and R ¹⁰ each independently represent an aryl group which may have a substituent;
Represents a furyl group or a thienyl group, L ³ represents a mono, tri, or pentamethine group which may have a substituent,
Two substituents on the tri- or pentamethine group may be connected to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the quinone ring and the benzene ring may have a substituent. X ^- is a counter anion. ]

Here, R ⁹ and R ¹⁰ in the formula (III) are specifically phenyl, 1-naphthyl, 2-naphthyl, 2-furyl, 3-furyl, 2-thienyl. ,
3-thienyl group and the like, and as a substituent thereof, an alkyl group, an alkoxy group, a dialkylamino group,
A hydroxy group, or a halogen atom, and the like; examples of the substituent in L ³ include an alkyl group, an amino group, and a halogen atom; examples of the substituent in the quinone ring and the benzene ring include an alkyl group, an alkoxy group, Examples thereof include a nitro group and a halogen atom.

Further, as the pyrylium-based and thiapyrylium-based dyes, the following general formulas (IVa), (IVb) and
Those represented by (IVc) are preferred.

[0035]

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[In formulas (IVa), (IVa) and (IVc), Y ³
And Y ⁴ each independently represent an oxygen atom or a sulfur atom, and R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ each independently represent a hydrogen atom or an alkyl group, or R ¹¹ and R ¹³ , and R ¹² and R
¹⁴ may be linked to each other to form a cycloalkene ring having 5 or 6 carbon atoms, and L ⁴ represents a mono, tri, or pentamethine group which may have a substituent, and the tri or pentamethine group The above two substituents may be connected to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the pyrylium ring and the thiapyrylium ring may have a substituent. Two substituents may be linked to each other to form a fused benzene ring. X ^- is a counter anion. ]

Here, the substituent in L ⁴ of formulas (IVa), (IVa) and (IVc) is an alkyl group, an amino group,
Or a halogen atom, and examples of the substituent on the pyrylium ring and the thiapyrylium ring include an aryl group such as a phenyl group and a naphthyl group.

Further, as the aminium-based and immonium-based dyes, those having at least one N, N-diaryliminium salt skeleton are preferable.
Those represented by (Va) or (Vb) are preferred.

[0039]

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In the formulas (Va) and (Vb), R^Fifteen, R¹⁶,
R¹⁷, R¹⁸, R¹⁹, R²⁰, R^{twenty one}, And R ^{twenty two}Are independent
Represents a hydrogen atom, an alkyl group, or a phenyl group,
The non-ring and the benzene ring may have a substituent. X
^-Represents a counter anion. Note that the electronic bond (─) in the formula (Vb)
Indicates a resonance state with another electronic bond. ]

Here, examples of the substituent on the quinone ring and the benzene ring in the formulas (Va) and (Vb) include an alkyl group, an alkoxy group, an acyl group, a nitro group, and a halogen atom.

Incidentally, the above-mentioned general formulas (Ia to c), (II), (III),
Examples of the counter anion X ⁻ in (IVa to c) and (Va to b) include, for example, Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , PF
₆ ^-, and, BF ₄ ^-, etc. of an inorganic acid anion, benzenesulfonic acid inorganic borate such, p- toluenesulfonic acid, naphthalenesulfonic acid, acetic acid, and methyl, ethyl, propyl, butyl, phenyl, methoxyphenyl, naphthyl And organic acid anions such as organic boric acid having an organic group such as difluorophenyl, pentafluorophenyl, thienyl and pyrrolyl.

As described above, the quinoline dyes represented by the general formulas (Ia to c), the indole or benzothiazole dyes represented by the general formula (II), and the amino acids represented by the general formula (III) The following are specific examples of the benzene dye, the pyrylium-based or thiapyrylium-based dye represented by the general formula (IVa to c), and the aminium-based or immonium-based dye represented by the general formula (Va to b). .

[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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The amount of the photothermal conversion material described above added to the composition of the present invention is 0.1 to 30% by weight, preferably 0.5 to 20% by weight based on the total amount of the resin components (A) and (B). %, Particularly preferably 1 to 12% by weight.

The positive photosensitive composition of the present invention contains (A) a novolak resin in addition to the three components described above, in order to increase the difference in solubility between exposed and unexposed areas in an alkali developing solution. It is preferable to contain a dissolution inhibitor that reduces the solubility of a mixture of (B) a polyvinyl ester resin and (C) a photothermal conversion substance in an alkali developer.
Such a dissolution inhibitor is specifically a compound which is presumed to form a hydrogen bond with the novolak resin as the component (A) to reduce the solubility of the resin. Preferably, it hardly absorbs light in the infrared region and is not decomposed by light in the near infrared region.

Examples of the dissolution inhibitor include sulfonic acid esters, phosphoric acid esters, aromatic carboxylic acid esters, aromatic disulfones, carboxylic anhydrides, and aromatic sulfonic acid esters described in detail in JP-A-10-268512. Ketones, aromatic aldehydes, aromatic amines, aromatic ethers, etc., having a lactone skeleton, N, N-diarylamide skeleton, and diarylmethylimino skeleton, which are also described in detail in JP-A-11-190903. Acid-color-forming dye also used as an agent;
Non-ionic surfactants and the like described in detail in JP-A No. 4 can be mentioned.

The content of the dissolution inhibitor in the positive photosensitive composition of the present invention is preferably 0 to 50% by weight, more preferably 0 to 30% by weight,
Particularly preferred is 20% by weight.

The positive photosensitive composition of the present invention may optionally contain, for example, Victoria Pure Blue (425
95), crystal violet (42555), crystal violet lactone, auramine O (4100
0), Kachiron Brilliant Flavin (Basic 1)
3), Rhodamine 6 GCP (45160), Rhodamine B (45170), Safranin OK 70: 100 (50
240), Erioglaucine X (42080), Fast Black HB (26150), No. 120 / Lionol Yellow (21090), Lionol Yellow G
RO (21090), Shimla First Yellow 8G
F (21105), Benzidine Yellow 4T-564D
(21095), Shimla Fast Red 4015
(12355), Lionol Red B4401 (158)
50), Fast Gen Blue TGR-L (7416
0) and a colorant such as a pigment or dye such as Lionol Blue SM (26150). Here, the numbers in parentheses above indicate the color index (C.I.
I. ).

The content ratio of the colorant in the positive photosensitive composition of the present invention is preferably 0 to 50% by weight, more preferably 0.5 to 30% by weight,
Particularly preferred is 20% by weight.

In the positive photosensitive composition of the present invention, in addition to the above components, for example, a coating improver, a developability improver, an adhesion improver, a sensitivity improver, a sensitizer and the like are usually used. Various additives may further be contained in a range of preferably 10% by weight or less, more preferably 5% by weight or less.

The positive photosensitive composition of the present invention does not contain an onium salt, a diazonium salt and a quinonediazide compound, and thus has substantially no sensitivity to ultraviolet light. More specifically, before and after irradiation with light having a wavelength of 360 to 450 nm, there is no significant difference in solubility in an alkali developing solution, which means that it has no image forming function in a practical sense. In other words, the positive photosensitive composition according to the present invention is a white fluorescent lamp (Mitsubishi Electric Corp. 36
W white fluorescent lamp NEOLMI SUPER FLR40S-W / M /
36) Under the following conditions, even when left at a light intensity of 400 lux for 10 hours, there is no substantial difference in solubility in an alkali developing solution. The fact that no significant difference is caused in the solubility means that the solubility in the alkali developer hardly changes before and after standing for 10 hours. The positive photosensitive composition of the present invention is usually
After coating on the support surface as a solution in which each of the above components is dissolved in an appropriate solvent, by heating and drying, a positive photosensitive lithographic printing plate having a photosensitive composition layer formed on the support surface is obtained. .

Here, the solvent is not particularly limited as long as it has a sufficient solubility for the components used and gives good coating properties. Examples thereof include methyl cellosolve and
Cellosolve solvents such as ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate , Propylene glycol solvents such as dipropylene glycol dimethyl ether, butyl acetate, amyl acetate, ethyl butyrate, butyl butyrate, diethyl oxalate, ethyl pyruvate, ethyl-2-hydroxybutyrate, ethyl acetoacetate, methyl lactate, ethyl lactate, Ester solvents such as methyl 3-methoxypropionate, heptanol Hexanol, diacetone alcohol, alcohol solvents such as furfuryl alcohol, cyclohexanone, ketone solvents such as methyl amyl ketone,
Highly polar solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; acetic acid; a mixed solvent thereof; and a mixture of these with an aromatic hydrocarbon. The usage ratio of the solvent is usually in the range of about 1 to 20 times by weight based on the total amount of the photosensitive composition.

As the coating method, conventionally known methods such as spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, curtain coating and the like can be used. The amount of application varies depending on the application, but usually 3 to 70 mg as a dry film thickness.
/ Dm ^2, preferably from 5 to 50 mg / dm ^2, particularly preferably in the range of 10 to 30 mg / dm ^2. The drying temperature at that time is, for example, about 30 to 170 ° C., preferably about 40 to 150 ° C.

In order to further ensure the effects of the present invention, for example, about 40 to 100 ° C., preferably 40 to 100 ° C.
It is preferable to perform a heat treatment at a temperature of about 70 ° C. for about 1 minute to 50 hours, preferably for about 30 minutes to 20 hours.

The support is made of aluminum,
Metal plate such as zinc, copper, steel, aluminum, zinc, copper,
Metal plates plated or evaporated with iron, chromium, nickel, etc.
Examples include paper, paper coated with resin, paper to which metal foil such as aluminum is adhered, plastic film, plastic film subjected to hydrophilic treatment, and glass plate. Inside,
Preferable is an aluminum plate, which has been subjected to surface treatment such as graining by electrolytic etching or brush polishing in a hydrochloric acid or nitric acid solution, anodizing treatment in a sulfuric acid solution, and, if necessary, sealing. Aluminum plates are more preferred. The surface roughness of the support is JIS B0
Average roughness R _a as defined in 601, typically 0.3
The thickness is 1.0 μm, preferably about 0.4 to 0.8 μm.

The light source for imagewise exposing the positive photosensitive composition layer in the present invention includes mainly laser light sources such as HeNe laser, argon ion laser, YAG laser, HeCd laser, semiconductor laser and ruby laser. In particular, when an image is formed by heat generated by absorbing light, a light source that generates a near-infrared laser beam of 650 to 1300 nm is preferable.
Ruby laser, YAG laser, semiconductor laser, L
A solid-state laser such as an ED can be used. In particular, a small-sized and long-life semiconductor laser or a YAG laser is preferable. Usually, after scanning and exposure with these light sources, an image is formed by developing with a developer.

The laser light source usually scans the surface of the photosensitive composition layer as a high-intensity light beam (beam) condensed by a lens, and the sensitivity of the photosensitive composition layer according to the present invention is responsive to the scanning. The characteristic (mJ / cm ² ) may depend on the light intensity (mJ / s · cm ² ) of the received laser beam. Here, the light intensity of the laser beam is obtained by dividing the amount of energy per unit time (mJ / s) of the laser beam measured by the optical power meter by the irradiation area (cm ² ) of the laser beam on the surface of the photosensitive composition layer. Can be obtained by The irradiation area of the laser beam is usually defined as an area of a portion exceeding 1 / e ² intensity of the laser peak intensity, but it can be simply measured by exposing a photosensitive composition exhibiting a reciprocity law. .

In the present invention, the light intensity of the light source is
It is preferably at least 2.0 × 10 ⁶ mJ / s · cm ² , particularly preferably at least 1.0 × 10 ⁷ mJ / s · cm ² . When the light intensity is in the above range, the sensitivity characteristic of the positive photosensitive composition layer in the present invention can be improved, and the scanning exposure time can be shortened, which is a great practical advantage.

Examples of the developing solution used for developing the positive photosensitive body obtained by imagewise exposing the positive photosensitive lithographic printing plate of the present invention include sodium silicate, potassium silicate, lithium silicate, ammonium silicate, sodium metasilicate, and sodium metasilicate. Potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, dibasic sodium phosphate, tertiary sodium phosphate,
Inorganic alkali salts such as ammonium diphosphate, tertiary ammonium phosphate, sodium borate, potassium borate and ammonium borate, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, monobutylamine, mono Ethanolamine,
An alkaline developer comprising an aqueous solution of about 0.1 to 5% by weight of an organic amine compound such as diethanolamine, triethanolamine, monoisopropanolamine and diisopropanolamine is used. Among them, alkali metal silicates such as sodium silicate and potassium silicate which are inorganic alkali salts are preferable. Incidentally, a surfactant such as an anionic surfactant, a nonionic surfactant, or an amphoteric surfactant, or an organic solvent such as alcohol can be added to the developer as required.

The development is usually carried out by immersion development, spray development, brush development, ultrasonic development, or the like.
It is carried out at a temperature of about 50 to about 50C, particularly preferably about 15 to 45C.

[0072]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Examples 1 to 6, Comparative Examples 1 and 2 An aluminum plate (0.24 mm thick) was degreased in a 5% by weight aqueous solution of sodium hydroxide at 60 ° C. for 1 minute, In a hydrochloric acid aqueous solution having a concentration of mol / liter, a temperature of 25 ° C., a current density of 60 A / dm ² , and a treatment time of 3
Electrolytic etching was performed under the condition of 0 second. Then, after a desmut treatment at 60 ° C. for 10 seconds in a 5% by weight aqueous sodium hydroxide solution,
Anodizing was performed under the conditions of a temperature of 20 ° C., a current density of 3 A / dm ² , and a processing time of 1 minute. In addition, hot water at 80 ° C
Hot water sealing was performed for 2 seconds to produce an aluminum plate for a lithographic printing plate support.

The following sample photosensitive solution was applied to the surface of the obtained aluminum plate support using a wire bar, dried at 85 ° C. for 2 minutes, and then stabilized at 55 ° C. to obtain a coating amount of 2.
A positive photosensitive lithographic printing plate having a positive photosensitive composition layer of ² g / m ² was prepared. Sample photosensitive solution: (A) novolak resin (phenol / m-cresol /
p-cresol = 50/30/20, weight average molecular weight =
(9,000 Sumitomo Jurez Co., Ltd.) ... 100 parts by weight minus the amount of the following component (B) (B) polyvinyl ester-based resin ... (C) Photothermal conversion material: II-9 ... 3 parts by weight Colorant: ethyl violet ... 3 parts by weight Solvent: methyl cellosolve ... 900 parts by weight

The obtained positive-type photosensitive lithographic printing plate was mounted on a rotating drum, and a semiconductor laser (manufactured by Applied Techno Co., Ltd.) having a wavelength of 830 nm and an output of 40 mW was irradiated with a yellow light under a yellow light while rotating the drum. And then immersed in an alkali developing solution (a 6-fold diluted solution of “SDR-1” manufactured by Konica) at 28 ° C., followed by light rubbing and development.

At this time, 120 mJ / cm ² and 240 mJ / cm ²
Exposure was performed at an exposure energy (sensitivity) of J / cm ² , and the residual film ratio when a positive image having a width of 25 μm was obtained by changing the development time was measured. The larger the residual film ratio, the better the results.

The residual film ratio of the obtained positive image was measured by using a reflection densitometer (“RD-514” manufactured by Macbeth) to measure the reflection density before and after development in the non-exposed area. The residual film ratio (%) was determined from the ratio of each value obtained by subtracting the value of the reflection density of the support surface before the layer was formed. still,
The origin of the compounded resin is described below the table. From the results in the table, it is understood that the composition has an effect in containing the polyvinyl ester resin.

[0078]

[Table 1]

[Blended resin] VA-1: Coponyl NP-160 (vinyl acetate / acrylate modified resin, manufactured by Nippon Synthetic Chemical Co.) VA-2: poly (vinylpyrrolidone / vinyl acetate) = copolymerization ratio 3 / 7, (Tokyo Kasei Kogyo Co., Ltd.) VA-3: Gosenil M50-Y0 (polymerized resin in vinyl acetate, manufactured by Nippon Synthetic Chemical Company) VA-4: Gosenil M35-X6 (vinyl acetate high polymer resin, manufactured by Nippon Synthetic Chemical Company) The positive-type photosensitive lithographic printing plate obtained above was irradiated with a 400 lux light intensity from a white fluorescent lamp (36 W white fluorescent lamp manufactured by Mitsubishi Electric Corporation "Neorumi Super FLR40S-W / M / 36"). When the same developing treatment as described above was performed after leaving the sample for 10 hours, there was no substantial film reduction in any of the Examples and Comparative Examples, and the handleability under a white fluorescent lamp was good. It was.

[0080]

According to the present invention, it is insensitive to light in the ultraviolet region, has excellent handleability under a white fluorescent lamp, and is sensitive to light in the near-infrared region, and has sensitivity and chemical resistance. In addition, it is possible to provide a positive photosensitive composition and a positive photosensitive lithographic printing plate which are excellent in contrast between an image portion and a non-image portion and which sufficiently retain the residual film ratio in the image portion.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H025 AA01 AA04 AA06 AB03 AC08 AD03 CB07 CB08 CB10 CB14 CB15 CB16 CB29 CB41 CC11 CC20 FA17 2H096 AA06 BA09 EA04 EA23 GA08 2H114 AA04 AA23 AA24 DA21 DA21 DA21 DA21 EA02 EA05 EA08

Claims (8)

[Claims] 1. A positive photosensitive composition comprising (A) a novolak resin, (B) a polyvinyl ester resin and (C) a photothermal conversion material. 2. The positive photosensitive composition according to claim 1, wherein the weight ratio (%) of the novolak resin to the polyvinyl ester resin is in the range of 99 to 65: 1 to 35. 3. The positive photosensitive composition according to claim 1, wherein the polyvinyl ester-based resin is a polyvinyl carboxylate-based resin. 4. The positive photosensitive composition according to claim 3, wherein the polyvinyl carboxylate resin is a polyvinyl acetate resin. 5. The positive photosensitive composition according to claim 4, wherein said polyvinyl acetate resin is polyvinyl acetate. 6. The polyvinyl acetate resin is selected from the group consisting of (meth) acrylate, (meth) acrylic acid, acrylonitrile, styrene, maleic anhydride, maleimide, acrylamide, N-vinylpyrrolidone, ethylene and chloroethylene. 5. A copolymer containing at least one of the above and vinyl acetate as a copolymer component.
The positive photosensitive composition as described in the above. 7. A dissolution inhibitor which reduces the solubility of a mixture comprising (A) a novolak resin, (B) a polyvinyl ester-based resin and (C) a photothermal conversion substance in an alkali developing solution. Item 7. The positive photosensitive composition according to any one of Items 1 to 6. 8. A positive-working photosensitive lithographic printing plate having a layer comprising the positive-working photosensitive composition according to claim 1 on a support.