JPH11143076A - Positive photosensitive composition and photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive composition and a lithographic printing plate which are excellent in the contrast of an exposed portion and the contrast of an unexposed portion, and have a sufficient residual film ratio in an image portion. SOLUTION: A positive photosensitive composition comprising an alkali-soluble organic polymer having a phenolic hydroxyl group and a base coloring dye.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photosensitive lithographic printing plate, a proof for simple proof printing, a wiring board, a copper etching resist for gravure, a resist for a color filter used in flat display manufacturing, a photoresist for LSI manufacturing, and the like. The present invention relates to a novel positive-type photosensitive composition for light in the ultraviolet to near-infrared wavelength range used for (1). In particular, the present invention relates to a positive photosensitive composition and a positive photosensitive lithographic printing plate suitable for direct plate making using a semiconductor laser, a YAG laser, or the like.

[0002]

2. Description of the Related Art With the advance of computer image processing technology, a photosensitive or heat-sensitive direct plate making in which a resist image is directly formed by a laser beam 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 view of miniaturization, environmental light during plate-making work, and plate material cost. Was. On the other hand, conventionally, as an image forming method using laser exposure or heat sensitivity, a method of forming a color material image using a sublimation transfer dye and a method of preparing a lithographic plate have been known. In the latter case, for example, a method of preparing a lithographic printing plate by utilizing a crosslinking reaction of a diazo compound (for example,
No. 151024, Japanese Patent Publication No. 2-51732,
No. -15603, Tokuhei 3-34051, Tokubo Sho61
21831, JP-B-60-12939, U.S. Pat. No. 3,664,737, etc.) and a method for preparing a lithographic printing plate by utilizing a decomposition reaction of nitrocellulose (for example, JP-A-50-102403, 50-102401
And other publications are known.

In recent years, a technique of combining a chemically amplified photoresist with a long-wavelength light-absorbing dye has been found. For example, JP-A-6-43633 discloses a photosensitive material in which a specific squarylium dye is combined with a photoacid generator, a binder and the like. Further, as a technique similar to this, there has been proposed a technique of preparing a lithographic printing plate by imagewise exposing a photosensitive layer containing an infrared absorbing dye, a latent Bronsted acid, a resol resin and a novolak resin to an image by a semiconductor laser or the like ( JP-A-7-20629
Further, a technique using an s-triazine compound instead of the latent Bronsted acid is also known (Japanese Patent Application Laid-Open No. Hei 7-27129).

Japanese Patent Application Laid-Open No. 9-43847 discloses a resist material which changes the crystallinity of a photosensitive material by heating by irradiation of infrared rays, and a pattern forming method using the same. However, according to the study by the present inventors, these conventional techniques have not always had sufficient characteristics in practical use. For example, in the case of a photosensitive material that requires a heat treatment after exposure, the stability of the quality of the obtained image is not always satisfied due to fluctuations in the processing conditions. on the other hand,
In the case of a photosensitive material that does not require such a heat treatment after exposure, the contrast in the exposed and unexposed areas is insufficient, and as a result, the non-image areas are not sufficiently removed, Was not sufficiently maintained.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, that is, the object of the present invention is to
It is an object of the present invention to provide a novel positive photosensitive composition and a positive photosensitive lithographic printing plate which are excellent in contrast and have a sufficient residual film ratio in an image area.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies and have found that the above problem can be solved by using a dye that develops a color with a base, and have achieved the present invention. That is, the gist of the present invention is to provide a positive photosensitive composition characterized by containing an alkali-soluble organic polymer substance having a phenolic hydroxyl group and at least a base coloring matter having a property of coloring with a base, and using the same. Existing in the positive-working photosensitive lithographic printing plate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The composition of the present invention contains a phenol-soluble polymer and a dye that forms a color under the action of a base (hereinafter, referred to as a color-forming dye), and contains the base-color-forming dye and the alkali-soluble organic compound having the phenolic hydroxyl group. The polymer material forms a matrix structure through hydrogen bonding, and as a result, a high effect of suppressing dissolution of the alkali-soluble organic polymer material in an aqueous alkali solution is generated. One example of such a matrix structure formation is shown below.

[0009]

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[0010] Such a matrix structure, when irradiated with light,
Hydrogen bonds are dissociated by the photochemical change of the base chromogenic dye constituting the matrix structure or the change due to heat generated by light absorption, and the high dissolution inhibiting effect is lost.Moreover, the hydrogen bonds of the matrix are dissociated. When the base color-forming dye alone comes into contact with the developing solution during the development processing, the base (OH ⁻ ) abstracts the protons of the —OH and —NH— groups of the dye to generate a carbonyl group or an imino group,
Since the lactone ring is opened to develop the color of the dye and increase the solubility in a developing solution, a positive image having high contrast can be formed. Examples of the coloring mechanism of the dye are shown below.

[0011]

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The alkali-soluble organic polymer having a phenolic hydroxyl group used in the composition of the present invention includes:
Novolak resins, resole resins, polyvinylphenol resins, copolymers of acrylic acid derivatives having a phenolic hydroxyl group, and the like. Among these, a novolak resin, a resol resin or a polyvinylphenol resin is preferred. Particularly preferred is a novolak resin or a polyvinylphenol resin.

As the novolak resin, phenol, m
-Cresol, o-cresol, p-cresol, 2,
5-xylenol, 3,5-xylenol, resorcinol, pyrogallol, bisphenol, bisphenol-
A, at least one kind of aromatic hydrocarbons such as trisphenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, propylphenol, n-butylphenol, t-butylphenol, 1-naphthol and 2-naphthol; Polycondensation with aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and furfural and at least one aldehyde or ketone selected from ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone under an acidic catalyst Is mentioned.

Instead of formaldehyde and acetaldehyde, paraformaldehyde and paraaldehyde, respectively, may be used. The weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (hereinafter abbreviated as GPC) of the novolak resin (hereinafter, the weight average molecular weight measured by GPC is abbreviated as Mw) is preferably 1,000 to 15,000, particularly preferably. Of 1,500 to 10,000 are used.

The aromatic hydrocarbons of the novolak resin are more preferably phenol, o-cresol, m
-Cresol, p-cresol, 2,5-xylenol, and 3,5-xylenol, at least one phenol selected from resorcinol, formaldehyde,
Novolak resins polycondensed with at least one selected from aldehydes such as acetaldehyde and propionaldehyde are exemplified.

In particular, the mixing ratio of m-cresol: p-cresol: 2,5-xylenol: 3,5-xylenol: resorcin is 40 to 100: 0 to 5 in molar ratio.
Phenols of 0: 0 to 20: 0 to 20: 0 to 20 or phenols and aldehydes having a molar ratio of phenol: m-cresol: p-cresol of 1 to 100: 0 to 70: 0 to 60 Novolak resins which are polycondensates with the compounds are preferred. Of the aldehydes, formaldehyde is particularly preferred. Incidentally, the photosensitive composition of the present invention,
It may further contain a solvent inhibitor, in which case m-cresol: p-cresol: 2,5-xylenol:
The mixing ratio of 3,5-xylenol: resorcinol in a molar ratio of 70 to 100: 0 to 30: 0 to 20: 0 to 20 or a mixing ratio of phenol: m-cresol: p-cresol in a molar ratio 10 to 100: 0 to 6
Novolak resins which are polycondensates of phenols and aldehydes at 0: 0 to 40 are preferred.

As the polyvinylphenol resin, o-
Hydroxystyrenes such as hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (o-hydroxyphenyl) propylene, 2- (m-hydroxyphenyl) propylene, and 2- (p-hydroxyphenyl) propylene; Two or more (co) polymers are included. Hydroxystyrenes include halogen such as chlorine, bromine, iodine, fluorine, or C ₁ to
It may have a substituent such as an alkyl group of C _4, thus Polyvinyl phenols, including good polyvinyl phenol which may have an alkyl group having halogen or C ₁ -C ₄ the aromatic ring.

The polyvinyl phenol resin is usually obtained by polymerizing hydroxystyrenes which may have a substituent alone or in combination of two or more hydroxystyrenes in the presence of a radical polymerization initiator or a cationic polymerization initiator. Such a polyvinyl phenol resin may be partially hydrogenated. Further, a resin in which some OH groups of polyvinylphenols are protected by a t-butoxycarbonyl group, a pyranyl group, a furanyl group, or the like may be used. Mw of the polyvinyl phenol resin is preferably 1,000 to 100,000.
0, particularly preferably 1,500 to 50,000.

The polyvinyl phenol resin is more preferably a polyvinyl phenol which may have an alkyl substituent having ₁ to ₄ carbon atoms on the aromatic ring, and an unsubstituted polyvinyl phenol is particularly preferred. If the Mw of the novolak resin or the polyvinyl phenol resin is smaller than the above range, a sufficient coating film cannot be obtained. Tend not to be.

The resol resin can be obtained in the same manner as in the novolak resin except that an alkali catalyst is used instead of an acid catalyst, and a resol resin having the same preferable molecular weight and polycondensation monomer composition as the novolak resin is preferable. The compounding ratio of the alkali-soluble organic polymer having a phenolic hydroxyl group is from 2 to 98% by weight, preferably from 5 to 95% by weight, more preferably from 10 to 95% by weight, based on the total solids in the photosensitive composition of the present invention. 90% by weight.

The base color-forming dye used in the composition of the present invention is not particularly limited as long as it has a function of forming a color by the action of a base. It preferably has a (thio) lactone or sulfolactone skeleton in its structure,
In the hydrogen ion concentration region of H3 or more, particularly preferably pH 5 or more, a dye which develops a color by opening the (thio) lactone or sulfolactone skeleton in the dye as shown above is exemplified. Note that (thio) lactone represents lactone or thiolactone. More specifically, examples of the base color-forming dye include a dye represented by the following general formula (A) and having the property of forming a color with a base.

[0022]

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(Wherein W represents a carbonyl group, a thiocarbonyl group or a sulfonyl group, and ring A, ring B and ring C are each independently a 1 to 3 ring aromatic hydrocarbon group or 1 to 3 ring
Represents a three-ring aromatic heterocyclic group. R ^{u1 to} R ^u12 each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or an acyl group having 2 to 15 carbon atoms which may have a substituent; An alkoxy group having 1 to 15 carbon atoms which may have a substituent, an acyloxy group having 2 to 15 carbon atoms which may have a substituent, and 2 carbon atoms which may have a substituent 15 represents an alkoxycarbonyl group, trimethylsilyloxy group, optionally substituted amino group, hydroxyl group, halogen atom, nitro group, isocyanato group or thioisocyanato group. Ring B and ring C may be bonded to each other via a bonding group. )

In the general formula (A), preferably, ring A is a benzene ring, and rings B and C are a benzene ring, a naphthalene ring or an indole ring. When R ^{u1 to} R ^u12 are amino groups, they may have an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 15 carbon atoms, or an aminocarbonyl group as a substituent. You may have. The alkyl group of the alkyl group, the alkoxy group and the amino group ^represented by R ^{u1 to} R ^u12 has 1 carbon atom.
Is preferably from 10 to 10, and more preferably from 1 to 5. R ^u1
~ R ^u12 represents an acyloxy group, an alkoxycarbonyl group,
The number of carbon atoms in the case of an acyl group is preferably 2 to 10, and the number of carbon atoms of an aryl group as a substituent of an amino group is preferably 6 to 10. Preferred ^{Ru1 to Ru4} include a hydrogen atom, a hydroxyl group, a bromine atom, an iodine atom, a chlorine atom, an alkyl group,
Alkoxy group, an acyloxy group, an alkoxycarbonyl group (the alkyl group, an alkoxy group, an acyloxy group, an alkoxycarbonyl group, further, may also have a substituent group), R ^u5 to R ^{u 12} is a hydrogen atom , An alkyl group, an alkoxy group, an acyloxy group, an alkoxycarbonyl group (an alkyl group, an alkoxy group, an acyloxy group, and an alkoxycarbonyl group may have a substituent), a bromine atom, a chlorine atom, an iodine atom, an amino group,
A substituted amino group, a hydroxyl group, and a nitro group. When the rings B and C are bonded, they are preferably bonded at the 0-position,
A preferred linking group which forms a membered ring is an oxygen atom or a sulfur atom.

Particularly preferably, R ^{u1 to} R ^u4 are a hydrogen atom, a bromine atom, a chlorine atom or an alkyl group, and R ^{u5 to} R ^u
u12 is a hydrogen atom, a hydroxyl group, a nitro group, an amino group, a substituted amino group, a bromine atom, a chlorine atom, and W is a carbonyl group or a sulfonyl group. In particular, it is preferable that at least one of ^{Ru5 to Ru12} is a hydroxyl group or an amino group from which a proton is extracted by a base to form a carbonyl group or an imino group.

Hereinafter, specific examples of the base color-forming dye of the present invention are shown in Table 1, but the base color-forming dye of the present invention is not limited to the specific examples. In addition, W in the following formula
A represents a carbonyl group or a sulfonyl group.

[0027]

[Table 1]

[0028]

[Table 2]

The base color-forming dye may be a compound having a plurality of dyes in which two or more dyes are bonded directly or via a bonding group. The compounding amount of the base color-forming dye in the composition of the present invention,
When the dye is a polymer, it is 1 to 9 in the total solid content of the composition.
It is 8% by weight, preferably 3 to 80% by weight, more preferably 5 to 70% by weight. When the dye is not a polymer, it is 1 to 50% by weight, preferably 3 to 40% by weight of the total solid content.
%, More preferably 5 to 30% by weight.

In the positive photosensitive composition of the present invention, an alkali-soluble organic polymer substance or a dye that forms a color with a base or a proton transfer complex absorbs light upon irradiation with light, and is generated by a photochemical reaction or light absorption. The action of heat destroys the above-mentioned proton transfer complex structure and the matrix structure of the alkali-soluble organic polymer substance centered on it, and significantly improves the solubility of the light-irradiated portion in an aqueous alkali solution, resulting in a high contrast positive appearance. Can be obtained. Further, in order to enhance the effect of improving the solubility by the heat generated by this photochemical reaction or light absorption, a photothermal conversion substance or a photochemical reaction is contained in the positive photosensitive composition. A positive-type photoreactive compound capable of forming a positive-type image by the action of (i) can be blended.

The photothermal conversion material used in the positive photosensitive composition of the present invention is not particularly limited as long as it generates heat when irradiated with light. More specifically, the wavelength range is 650.
Organic or inorganic pigments, organic dyes, metals and the like having an absorption band in a part or the whole of 〜1300 nm are exemplified. Specifically, for example, carbon black; graphite; titanium;
Metals such as chromium; metal oxides such as titanium oxide, tin oxide, zinc oxide, vanadium oxide, and tungsten oxide; metal carbides such as titanium carbide; metal borides;
Inorganic black pigments described in -322219,
Azo black pigment, "Lionol Green 2Y"
S "and" green pigment 7 ". Examples of the carbon black include “MA-7” and “MA-10”, which are products of Mitsubishi Chemical Corporation.
0 "," MA-220 ","# 5 ","# 10 ","#
"Color Black FW", a product of Degussa
2 "," FW20 "," Printex V "and the like.

Also, "special functional pigments" (edited by Ikemori and Hashiya, 1986, published by CMC Corporation), "chemical chemistry of functional pigments" (edited by Higaki, 1981, published by CMC Corporation), " Dye Handbook "(edited by Okawa, Hirashima, Matsuoka, Kitao, published by Kodansha)
Exciton Inc., a catalog published in 1995.
And dyes having absorption in the near infrared region described in Laser Dye Catalog issued in 1989.

Further, JP-A-2-2074, JP-A-2-2074
5, 2076, JP-A-3-97590, 9759
No. 1, No. 63185, No. 26593, No. 97589
And organic dyes described in each of the above publications and the product “IR820B” of Nippon Kayaku. Table 2 shows typical examples of dyes and pigments having absorption in the near infrared region as the light-to-heat conversion material.

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

[Table 5]

[0037]

[Table 6]

[0038]

[Table 7]

[0039]

[Table 8]

[0040]

[Table 9]

[0041]

[Table 10]

[0042]

[Table 11]

[0043]

[Table 12]

[0044]

[Table 13]

[0045]

[Table 14]

[0046]

[Table 15]

[0047]

[Table 16]

[0048]

[Table 17]

[0049]

[Table 18]

[0050]

[Table 19]

Of these, cyanine dyes, polymethine dyes, squarylium dyes, croconium dyes, pyrylium dyes, and thiopyrylium dyes are preferred, and cyanine dyes, polymethine dyes, pyrylium dyes, and thiopyrylium dyes are more preferred. Among these, a particularly preferred dye is a cyanine dye represented by the following general formula [I], a polymethine dye represented by the following general formula [II], or a pyrylium dye or a thiopyrylium dye represented by the following general formula [III]. is there.

[0052]

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[Wherein, R¹, R^TwoHas a substituent
Good C₈The following alkyl groups, wherein the substituents are
Nyl group, phenoxy group, alkoxy group, sulfonic acid group,
A carboxyl group; Q¹May have a substituent
Heptamethine group, wherein the substituent is C₆The following al
A kill group, a halogen atom, an amino group,
The tin group is bonded to the substituents on the two methine carbons
Optionally formed cyclohexene formed by
May contain a ring or a cyclopentene ring
And the substituent is C₆The following alkyl groups or halogen sources
Child; m¹, M ^TwoIs each 0 or 1;
Z¹, Z^TwoIs a group of atoms necessary to form a nitrogen-containing heterocyclic ring.
Yes; X^-Represents a counter anion. ]

[0054]

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[Wherein, R ^{3 to} R ⁶ are an alkyl group of C ₈ or less; Z ⁴ and Z ⁵ are an aryl group which may have a substituent, and the aryl group is a phenyl group, naphthyl group, a furyl group or a thienyl group, the substituents C ₄
An alkyl group, a dialkylamino group having a C ₈ an alkyl group, a C ₈ an alkoxy group and a halogen atom. Q ² represents a trimethine group or a pentamethine group; X ⁻ represents a counter anion. ]

[0056]

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Wherein Y ¹ and Y ² are an oxygen atom or a sulfur atom; R ⁷ , R ⁸ , R ¹⁵ and R ¹⁶ are a phenyl group or a naphthyl group which may have a substituent; ,
The substituent is an C ₈ an alkyl group or a C ₈ an alkoxy group; l ¹ and l ² are each independently 0 or 1
R ^{9 to} R ^{14 each} represent a hydrogen atom or an alkyl group of C ₈ or less, or R ⁹ and R ¹⁰ , R ¹¹ and R
¹² or R ¹³ and R ¹⁴ are mutually bonded

[0058]

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(Provided that R ^{17 to} R ¹⁹ are a hydrogen atom or an alkyl group having a carbon number of ₆ or less, and n represents 0 or 1); Z ³ may be a halogen atom or a hydrogen atom. , X represents a counter anion. The counter anion X ^{− in the above} formulas [I], [II] and [III] is, for example, Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄
^- , BF ₄ ^- and PF _6- ^{and the} like, and anions of organic acids such as benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, acetic acid and organic boric acid.

In particular, a dye having an organic borate anion as a counter ion is excellent in solubility in a coating solvent, so that a coating solution can be easily produced, and a solvent having a low boiling point can be used. The layer can be prevented from sticking to the application line roller, etc., and high-speed application becomes possible.
High productivity can be obtained. The mixing ratio of these photothermal conversion materials in the total solid content of the photosensitive composition of the present invention is from 0 to
It is 30% by weight, preferably 0-20% by weight, more preferably 0-15% by weight. Specifically, examples of such an organic borate anion include those represented by the following formula (L).

[0061]

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(Wherein, R ^{Q1 to} R ^Q4 each represent a hydrogen atom,
An alkyl group having 1 to 15 carbon atoms, an aromatic hydrocarbon ring group having 6 to 15 carbon atoms which may have a substituent, and a heterocyclic group having 4 to 15 carbon atoms which may have a substituent. Express. More specifically, R ^{Q1 to} R ^Q4 are each -CH ₃ ,-
_{C 2 H 5, -C 3 H} 7, -C 4 H 9, -C 4 H 9 -t,

[0063]

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And the like. The photosensitive layer may contain a coloring material other than the light-to-heat conversion material, if necessary. As a coloring material, a pigment or a dye is used. For example, Victoria Pure Blue (4
2595), Auramine O (41000), Katilon Brilliant Flavin (Basic 13), Rhodamine 6
GCP (45160), Rhodamine B (45170),
Safranin OK70: 100 (50240), Erioglaucine X (42080), First Black HB
(26150), No. 120 / Lionol Yellow (21090), Lionol Yellow GRO (2109
0), Shimla First Yellow 8GF (2110
5), benzidine yellow 4T-564D (2109)
5), Shimla Fast Red 4015 (1235)
5), Lionol Red B4401 (15850), Fast Gen Blue TGR-L (74160), Lionol Blue SM (26150) and the like. In addition,
The numbers in parentheses above indicate the color index (C.I.
I. ).

When the coloring material is contained, its compounding ratio is 1 to 50% by weight, preferably 2% by weight, based on the solid content of the whole photosensitive layer composition.
３０30% by weight. Next, examples of the positive-type photoreactive compound capable of forming a positive-type image by the action of the photochemical reaction of the composition of the present invention include onium salt compounds described in JP-A-60-175046, and US Pat. Nos. 3,666,473 and 4,115.
128, 4173470, JP-A-9-127690,
JP-A-9-106070; F. Thompson
"Introduction to Microlit
hography "ACS Publishing, No. 2,19, P
Naphthoquinonediazide compounds described in 112-121, etc., and JP-A-48-89003 and JP-A-5-12071.
4, 53-133429, 55-12995, 5
5-126236, 56-17345, 60-36
25, 60-10247, 60-37549, 6
0-112446, 59-45439, 60-36
25, 62-229242, 63-27829, 63-36240, 63-250642, etc., compounds which generate an acid upon exposure and dissociated by the acid-generating compound and the acid to increase solubility And the like. The mixing ratio of these positive-type photoreactive compounds is 0 to 50% by weight based on the total solid content of the photosensitive composition.
Preferably 0 to 30% by weight, more preferably 0 to 20%
% By weight.

The photosensitive composition of the present invention is usually used by dissolving each of the above components in a suitable solvent. As the solvent,
There is no particular limitation as long as the solvent has sufficient solubility for the components used and gives good coating properties, but methylcellosolve, ethylcellosolve, methylcellosolve acetate,
Cellosolve solvents such as ethyl cellosolve acetate,
Propylene glycol solvents such as 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, and dipropylene glycol dimethyl ether; butyl acetate; acetic acid Amyl, ethyl butyrate, butyl butyrate, diethyl oxalate, ethyl pyruvate, ethyl-2-hydroxybutyrate, ethyl acetoacetate, methyl lactate,
Ester solvents such as ethyl lactate and methyl 2-methoxypropionate; alcohol solvents such as heptanol, hexanol, diacetone alcohol and furfuryl alcohol; ketone solvents such as cyclohexanone and methyl amyl ketone; dimethylformamide; dimethylacetamide; N Highly polar solvents such as -methylpyrrolidone, or a mixed solvent thereof, or a mixture of these with an aromatic hydrocarbon. The proportion of the solvent used is usually 1 to 20 by weight based on the total amount of the photosensitive composition.
The range is about double.

The photosensitive composition of the present invention may contain various additives such as a coating improver, a development improver, an adhesion improver, a sensitivity improver, a sensitizer and the like within a range that does not impair the performance of the composition. It is also possible to contain. The photosensitive composition of the present invention can be advantageously used as a photosensitive lithographic printing plate by coating on a support. As a coating method used when providing the photosensitive layer on the support surface, conventionally known methods, for example, spin coating,
Wire bar coating, dip coating, air knife coating,
Roll coating, blade coating, curtain coating and the like can be used. The drying temperature or the heating temperature is, for example, 20 to 170 ° C, preferably 30 to 150 ° C.
Is adopted.

The thickness of the photosensitive layer is usually 0.3 to 7 μm,
Preferably 0.5-5 μm, more preferably 1.0-3
μm. As a support on which a photosensitive layer using the photosensitive composition of the present invention is provided, a metal plate such as aluminum, zinc, steel, and copper, and chromium, zinc, copper, nickel, aluminum, and iron are plated or evaporated. Examples include a metal plate, paper, a plastic film and a glass plate, paper coated with resin, paper covered with a metal foil such as aluminum, and a sheet such as a plastic film subjected to hydrophilic treatment. As the support for the photosensitive lithographic printing plate, surface treatment such as graining treatment by electrolytic etching or brush polishing in a hydrochloric acid or nitric acid solution, anodizing treatment in a sulfuric acid solvent, and if necessary, sealing treatment, etc. It is more preferable to use a coated aluminum plate.

The surface roughness of the support is generally indicated by the value of surface roughness Ra. This can be measured using a surface roughness meter. The support used in the present invention has an average roughness Ra of 0.3 to 1.0 μm.
m of an aluminum plate is preferable.
μm is more preferred. This support may be used as required.
Further, it can be used after being subjected to a surface treatment with an organic acid compound.

The light source for imagewise exposing the photosensitive composition of the present invention includes lamp light sources such as a xenon lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, a halogen lamp, and a metal halide lamp.
A laser light source such as a HeNe laser, an argon ion laser, a YAG laser, a HeCd laser, a semiconductor laser, and a ruby laser may be mentioned. In particular, when an image is formed by absorbing light and generating heat, 650 is used.
A light source that emits light such as a near-infrared laser having a wavelength of about 1300 nm is preferable, and examples thereof include a ruby laser, a YAG laser, a semiconductor laser, an LED, and other solid-state lasers. Lasers are preferred. With these laser light sources, usually, after scanning exposure, development can be performed with a developer to obtain an image.

The laser light source normally scans the surface of the photosensitive material as a high-intensity light beam (beam) condensed by a lens. The sensitivity characteristic of the positive type lithographic printing plate of the present invention (mJ / cm ² ) may depend on the light intensity (mJ / s · cm ² ) of the laser beam received on the photosensitive material surface. Here, the light intensity of the laser beam (mJ
/ S · cm ² ) is the amount of energy (mJ / s) of the laser beam on the plate surface per unit time measured with an optical power meter, and the beam diameter (irradiated area; cm ² ) on the surface of the photosensitive material It can be obtained by dividing the amount of energy per unit time by the irradiation area. The irradiation area of the laser beam is usually defined as the area of the portion exceeding 1 / e ² intensity of the laser peak intensity, but it can be simply measured by exposing a photosensitive material exhibiting a reciprocity law.

The light intensity of the light source used in the present invention is preferably 2.0 × 10 ⁶ mJ / s · cm ² or more, and 1.0 × 10 ⁷ mJ / s · cm ² or more. Is more preferred. When the light intensity is within the above range, the sensitivity characteristics of the positive photosensitive composition of the present invention are improved, and the scanning exposure time can be shortened.

The developer used for developing the photosensitive composition of the present invention is particularly preferably an alkali developer mainly composed of an aqueous alkali solution. Examples of the alkaline developer include aqueous solutions of alkali metal salts such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium metasilicate, potassium metasilicate, dibasic sodium phosphate, and tertiary sodium phosphate. No. The concentration of the alkali metal salt is preferably from 0.1 to 20% by weight. If necessary, an anionic surfactant, an amphoteric surfactant, or an organic solvent such as alcohol can be added to the developer.

[0074]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. [Production of Aluminum Plate] A 0.24 mm-thick aluminum plate (material 1050, tempered H16) was degreased in a 5% by weight aqueous sodium hydroxide solution at 60 ° C. for 1 minute, and then 0.5 mol In a hydrochloric acid aqueous solution having a concentration of 1 / liter, electrolytic etching was performed under the conditions of a temperature of 28 ° C., a current density of 60 A / dm ² , and a processing time of 40 seconds. Then, in a 4% by weight aqueous sodium hydroxide solution at 60 ° C., 12
After a desmutting treatment for 2 seconds, an anodic oxidation treatment was carried out in a 20% by weight sulfuric acid solution at a temperature of 20 ° C., a current density of 3.5 A / dm ² and a treatment time of 1 minute. In addition, 80 ° C
Hot water sealing treatment was performed for 20 seconds to prepare an aluminum plate as a lithographic printing plate support. The value of the average roughness Ra of this plate was 0.60 μm. The Ra value was measured using a surface roughness meter SE-3DH (manufactured by Kosaka Laboratory Co., Ltd.), scan length 4 mm, no high-frequency cutoff, low-frequency cutoff 0.
It was measured under the condition of 8 mm.

[Measurement Method of Coating Amount of Photosensitive Layer] A photosensitive lithographic printing plate obtained by coating a photosensitive solution on a support under the conditions shown in the following Examples, drying and heat-treating was used to form a 10 cm square plate. The sample was cut to the size of a sample. After measuring the weight of the sample piece, the photosensitive layer was dissolved and removed with acetone, the weight was measured again to determine the weight loss, and the weight per 1 m ² was calculated from the value to determine the weight loss.

[Remaining film ratio] The remaining film ratio was determined by the method described in Examples and Comparative Examples, in which the amount of the remaining coating film in the non-image area after development was determined in the same manner as described above. And determined according to the following criteria. A: 90% by weight or more of the remaining film remains. B: A residual film of 70% by weight or more and less than 90% by weight remains. C: 50% by weight or more and less than 70% by weight of the residual film remain. D: Less than 50% by weight of the remaining film remains.

Examples 1 to 10 and Comparative Examples 1 to 3 A photosensitive solution comprising the following components was applied on an aluminum plate prepared by the above-mentioned method using a wire bar, dried at 90 ° C. for 2 minutes, and then dried at 55 ° C. For 16 hours to obtain a lithographic printing plate. The amount of the coating film was 2.8 g / m ² .

(Photosensitive solution) 100 parts by weight of a novolak resin (Mw 4000) obtained by co-condensing an alkali-soluble polymer compound: phenol: m-cresol: p-cresol at a molar ratio of 20:50:30) with formaldehyde : Those described in Table-A 5 parts by weight Base color-forming dyes: those described in Table-A 10 parts by weight Solvent: cyclohexanone 900 parts by weight

Next, the sample was exposed to a lithographic printing plate exposure apparatus (Trend Setter 3244T, manufactured by Creo Corporation) using a 830 nm semiconductor laser as a light source at 212 lines of 3 to 97% at various exposure energies. The point image was image-exposed, and then developed at 28 ° C. using an alkaline developer (a 7-fold dilution of Konica SDR-1). The sensitivity was evaluated using the exposure amount at which a 3% halftone dot image was reproduced. The lower the exposure, the higher the sensitivity. The results are shown in Table-A.

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[Table 20]

* 1: The dyes used are as follows. (Base coloring dye)

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[Dye which is not base-color-forming]

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* 2: For S-53, S-54 and S-57, the corresponding compounds in Table 2 were used. Carbon black was manufactured by Mitsubishi Chemical Corporation, MA220; titanium monoxide was manufactured by Mitsubishi Materials Corporation, titanium black 12S. * 3: "F" indicates that the film was completely dissolved and no image was formed in the case of sensitivity, and the evaluation was not performed in the case of the residual film ratio.

[0087]

The photosensitive composition containing the base color-forming dye according to the present invention has excellent sensitivity to exposure at 830 nm and an excellent residual film ratio in the image area.

Claims (11)

[Claims] 1. A positive photosensitive composition comprising an alkali-soluble organic polymer having a phenolic hydroxyl group and a base-color-forming dye having the property of forming a color with at least a base. 2. The positive photosensitive composition according to claim 1, wherein the base color-forming dye is a dye that forms a color at a hydrogen ion concentration of pH 3 or more. 3. The positive electrode according to claim 1, wherein the alkali-soluble organic polymer having a phenolic hydroxyl group is at least one resin selected from a novolak resin, a resol resin and a polyvinylphenol resin. -Type photosensitive composition. 4. The positive photosensitive composition according to claim 1, wherein the base color-forming dye is a dye having a structure having a lactone skeleton or a thiolactone skeleton. 5. The positive photosensitive composition according to claim 1, wherein the base color-forming dye is a dye having a structure having a sulfolactone skeleton. 6. The positive photosensitive material according to claim 1, wherein the base color-forming dye is a dye represented by the following general formula (A) and having the property of forming a color with a base. Composition. Embedded image (Wherein W represents a carbonyl group, a thiocarbonyl group or a sulfonyl group, and ring A, ring B and ring C are each independently a 1 to 3 ring aromatic hydrocarbon group or 1 to 3 ring aromatic Represents a group heterocyclic group, wherein R ^{u1 to} R ^u12 each independently represent
A hydrogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, 2 to 15 carbon atoms which may have a substituent
An acyl group having 1 to 15 carbon atoms which may have a substituent
An alkoxy group having 2 to 2 carbon atoms which may have a substituent
15 acyloxy groups, an optionally substituted alkoxycarbonyl group having 2 to 15 carbon atoms, a trimethylsilyloxy group, an optionally substituted amino group, a hydroxyl group, a halogen atom, a nitro group, an isocyanato group Or a thioisocyanato group. Ring B and ring C may be bonded to each other via a bonding group. ) 7. The positive photosensitive composition according to claim 1, further comprising a photothermal conversion material that absorbs light from an image exposure light source and converts the light into heat. 8. The positive photosensitive composition according to claim 7, wherein the photothermal conversion substance is a near infrared absorbing dye. 9. The positive photosensitive composition according to claim 8, wherein the near infrared absorbing dye has an organic borate anion as a counter ion. 10. The positive photosensitive composition according to claim 7, wherein the photothermal conversion material is carbon black or titanium black. 11. A positive-working photosensitive lithographic printing plate comprising a support and a layer comprising the positive-working photosensitive composition according to claim 1.