JP2001042519A - Positive photosensitive composition and positive photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive photosensitive resin composition capable of forming an image superior in contrast between an image part and a nonimage and wide in development latitude and sufficient in film endurance, and more preferably, nonsensitive to ultraviolet rays and superior in handleability even under white fluorescent light and to provide the positive lithographic printing plate. SOLUTION: The positive photosensitive composition comprises a photothermoconverting material capable of absorbing light from an image exprosure light source and converting it into heat and a novolak resin and it contains no pyrolyzate obtained by decomposed the photothermoconverting material by action of the heat caused by absorbing the light of the exposure light source, and the novolak resin made from phenols comprising >=60 mol% o-cresol, and the positive lithographic printing plate is provided with a layer made from this photosensitive composition on the surface of a support.

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-nitrocarbinol 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 is known. I have.

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.

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, a method of producing a lithographic printing plate, and the like are known. For the latter, specifically, for example, a method of preparing a lithographic printing plate using a crosslinking reaction of a diazo compound, a method of preparing a lithographic printing plate using a decomposition reaction of nitrocellulose, and the like are known.

[0005] In recent years, a technique in which a long-wavelength light-absorbing dye is combined with a chemically amplified photoresist has been scattered. For example, JP-A-6-43633 discloses a specific squarylium-based dye, a photoacid generator, and a binder. And JP-A-7-20629 discloses an image-forming material containing an infrared absorbing dye, a latent Bronsted acid, a resol resin, and a novolak resin. The publication discloses an image forming material using an s-triazine compound instead of the latent Bronsted acid. These conventional techniques relating to image forming materials containing a long-wavelength light-absorbing dye are sensitive to light in the ultraviolet region, and the reaction proceeds during handling under a white fluorescent lamp. There is a problem that it is difficult to obtain. Further, JP-A-7-285
No. 275 discloses an image forming material containing a binder, a substance that absorbs light and generates heat, and a substance that is thermally decomposable and substantially reduces the solubility of the binder when not decomposed. It has been disclosed.

JP-A-7-285275 describes that a water-insoluble and alkaline water-soluble resin is preferable as a binder, and various resins including an o-cresol formaldehyde resin are exemplified. By the way, the thermally decomposable dissolution inhibitor in the technology of the publication is a substance that is decomposed by heat generated by absorbing a laser beam from a “substance that absorbs light and generates heat”, and includes an onium salt, a diazonium salt and Although it is described that quinonediazide compounds are applicable, these compounds are sensitive to light in the ultraviolet region, and thus have a problem in handling under a white light similarly to the above-mentioned technology. On the other hand, Japanese Patent Application Laid-Open No. 9-43847 discloses a resin containing a resin which is hardly soluble in an alkali developing solution and an infrared absorbing agent, changes its crystallinity by being heated by infrared irradiation or the like, and becomes alkali-soluble. In WO97 / 39894, a positive-working composition which does not change contains a polymer which can be developed with an aqueous solution and a compound which inhibits the aqueous developability of the polymer. Heat-sensitive, positive-acting compositions that do not change upon irradiation are each disclosed. Also, JP-A-9
Both the positive photosensitive compositions disclosed in JP-A-43847 and WO97 / 39894 disclose that the compositions contain a novolak resin.

[0007] 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.

However, according to the studies by the present inventors, the above-mentioned conventional technique has a disadvantage that an image obtained by the processing conditions is not always stable in a negative-type photosensitive composition requiring a heat treatment after exposure. . 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. Area is not sufficiently removed, and the residual film ratio of the image area is not sufficiently maintained.Therefore, there is a problem that the development latitude is narrow. It has been found that the tendency is remarkable in the positive-type compositions disclosed in JP-A-9-43847 and WO97 / 39894, which cause a difference in the properties.

On the other hand, the present applicant has solved the above-mentioned problem with a simple system in which a photochemical change of a photothermal conversion substance for light in the near infrared region and an alkali-soluble resin such as a novolak resin cannot be expected. The inventors have found that a photosensitive composition capable of forming a positive image can be obtained, and have previously filed a patent application (Japanese Patent Application Laid-Open No. 10-268512). It is disclosed that the photosensitive composition also contains a novolak resin, and various compounds are listed as a phenol component and an aldehyde component constituting the novolak. However, the photosensitive composition has not yet been practically sufficient.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has excellent contrast between an image portion (unexposed portion) and a non-image portion (exposed portion) before and after exposure. That is, the difference in solubility in the alkaline developer between the image area and the non-image area is large, the development latitude is wide, the residual film ratio of the image area is sufficiently maintained, and more preferably, it is insensitive to light in the ultraviolet region. Another object of the present invention is to provide a positive photosensitive composition and a positive photosensitive lithographic printing plate which are excellent in handleability under a white fluorescent lamp.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that a light-to-heat conversion material mainly for light in the near infrared region and a specific novolak resin,
It has been found that a composition using a novolak resin containing a relatively large amount of o-cresol can achieve the above-mentioned object, and the present invention has been completed. A positive photosensitive composition comprising a light-to-heat conversion substance that converts to heat and a novolak resin, wherein the composition is formed by the action of heat generated when the light-to-heat conversion substance absorbs light from an image exposure light source. The positive photosensitive composition contains no thermally decomposable substance that decomposes and the novolak resin is composed of phenols in which o-cresol accounts for 60 mol% or more. Another gist is a positive photosensitive composition that contains a photothermal conversion material that absorbs light from an image exposure light source and converts it into heat and a novolak resin, and is substantially insensitive to ultraviolet light. In the product, the novolak resin has an o-cresol of 6
It is present in a positive photosensitive composition which is composed of phenols occupying 0 mol% or more. Another gist is a grit of a positive photosensitive lithographic printing plate in which a layer made of the above photosensitive composition is formed on the surface of a support.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The positive photosensitive composition of the present invention is a heat-decomposable substance (hereinafter, referred to as a “heat-decomposable substance”) in which a photothermal conversion substance described below is decomposed by the action of heat generated by absorbing light from an image exposure light source. ) Is not included. Such a thermally decomposable substance is an onium salt, a diazonium salt and a quinonediazide compound as described in JP-A-7-28527, and the photosensitive composition of the present invention does not contain such a thermally decomposable compound. And has substantially no sensitivity to light in the ultraviolet region, and can be handled under white light. Further, since the photosensitive composition of the present invention does not contain such a thermally decomposable compound, the thermally decomposable substance is decomposed by image exposure, and the technology involved in the formation of such a decomposed image is based on a different premise. .

Here, the expression "substantially insensitive to light in the ultraviolet region" means that there is a substantially significant difference in solubility in an alkali developing solution before and after irradiation with light having a wavelength of 360 to 450 nm. For example, a white fluorescent lamp (36W white fluorescent lamp manufactured by Mitsubishi Electric Corporation "Neorumi Super FLR40S") has no practical image forming ability.
−W / M / 36 ”) at a light intensity of 400 lux.
It means that the solubility of the composition in an alkali developer after leaving for 0 hours shows substantially no change as compared with that before leaving. In the positive photosensitive composition of the present invention,
The photothermal conversion material that absorbs light from the image exposure light source and converts it into heat is not particularly limited as long as it is a compound that can convert the absorbed light into heat, but may be a part of a near infrared region of a wavelength range of 650 to 1300 nm or Among the organic or inorganic pigments and dyes having all absorption bands, 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), aminobenzene (so-called)
Polymethine-based), pyrylium-based, thiapyrylium-based, squarylium-based, croconium-based, azurenium-based, and the like, among which quinoline-based, indole-based, benzothiazole-based, aminobenzene-based, pyrylium-based, and thiapyrylium-based are preferred, and In addition, other dyes such as aminium-based, immonium-based, phthalocyanine-based, and anthraquinone-based dyes are also typical examples, and among them, aminium-based and immonium-based dyes are preferable.

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

[0016]

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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;
L ¹Examples of the substituent for are an alkyl group and an amino
Group, or a halogen atom, etc., in the quinoline ring.
Substituents include alkyl groups, alkoxy groups, nitro
Group, or a halogen atom.

As the indole and benzothiazole dyes, those represented by the following general formula (II) are particularly preferable.

[0020]

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[In the formula (II), Y ¹ and Y ² each independently represent a dialkylmethylene group or a sulfur atom, and R ³ and R ⁴ each independently may have a substituent. An alkyl group, 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 has a substituent Represents an optionally tri, penta, or heptamethine group,
Two substituents on the penta or heptamethine group may be connected to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the condensed benzene ring may have a substituent. Two adjacent substituents may be linked to each other to form a fused benzene ring. X ^- is a counter anion. ]

In the formula (II), examples of the substituent for R ³ and R ⁴ 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 dye, those represented by the following general formula (III) are particularly preferable.

[0024]

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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, specific examples of R ⁹ and R ¹⁰ in the formula (III) include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-furyl group, a 3-furyl group and a 2-thienyl group. ,
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; a substituent in L ³ includes an alkyl group, an amino group or a halogen atom; and a 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.

[0028]

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[In formulas (IVa), (IVb) 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, examples of the substituent for L ⁴ in formulas (IVa), (IVa) and (IVc) include an alkyl group, an amino group, a halogen atom and the like, and a substituent on a pyrylium ring and a thiapyrylium ring. Examples of the group include an aryl group such as a phenyl group and a naphthyl group.

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

[0032]

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[In the formulas (Va) and (Vb), R ¹⁵ , R ¹⁶ ,
R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or a group which may have a substituent. A good alkynyl group or an alkoxy group which may have a substituent, wherein R ¹⁹ and R ²⁰ each independently represent an alkyl group which may have a substituent, Alkenyl group which may have a substituent, alkynyl group which may have a substituent, alkoxy group which may have a substituent, acyloxy group which may have a substituent, or It shows a good phenyl group, and the benzene ring and the iminoquinone ring may have a substituent. X ^- is a counter anion. In addition, the electronic bond (─) in the formula (Vb) indicates a resonance state with another electronic bond. ]

Here, R ¹⁵ in the formulas (Va) and (Vb),
Examples of the substituent for R ¹⁶ , R ¹⁷ , R ¹⁸ , R ¹⁹ and R ²⁰ include an alkyl group, an alkoxy group, a carboxy group, an acyloxy group, an alkoxycarbonyl group, a hydroxy group,
Amino group, alkylamino group, halogenated alkyl group,
Or a halogen atom, and examples of the substituent on the benzene ring and the iminoquinone ring include an alkyl group, an alkoxy group, an acyl group, a nitro group, and a halogen atom.

Among these aminium-based and immonium-based dyes, R ¹⁵ and R in the aforementioned general formulas (Va) and (Vb)
^16, R ^17, and in R ¹⁸ is an alkyl group, or R ^19, and R ²⁰ is also an alkyl group, those R ^19, and R ²⁰ is a phenyl group having as a substituent a dialkylamino group, particularly preferred .

The above 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 ^-, SbF ₆ ^-, and, BF ₄ ^- inorganic acid anion, benzenesulfonic acid inorganic borate such as, p- toluenesulfonic acid, naphthalenesulfonic acid, acetic acid, and methyl,
Examples thereof include organic acid anions such as organic boric acid having an organic group such as ethyl, propyl, butyl, phenyl, methoxyphenyl, naphthyl, difluorophenyl, pentafluorophenyl, thienyl, and pyrrolyl.

As described above, the quinoline-based dyes represented by the general formulas (Ia to c), the indole-based or benzothiazole-based 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). .

[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[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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The novolak resin in the positive photosensitive composition of the present invention includes, for example, phenol, o-cresol, m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol, o-ethyl Phenol, m-ethylphenol, p-ethylphenol, propylphenol, n-butylphenol, tert-
Butylphenol, 1-naphthol, 2-naphthol,
Pyrocatechol, resorcinol, hydroquinone, pyrogallol, 1,2,4-benzenetriol, phloroglucinol, 4,4'-biphenyldiol, 2,2
-At least one phenol such as bis (4'-hydroxyphenyl) propane is converted to aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and furfural (in addition to paraformaldehyde in place of formaldehyde) under acidic catalysis. , Acetaldehyde may be used in place of acetaldehyde.) Or a resin polycondensed with at least one of ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and is a phenolic hydroxyl group-containing alkali-soluble resin. The resin is commonly used as a binder resin for the photosensitive composition.

Among them, the novolak resin in the present invention is:
It is essential that o-cresol is composed of phenols occupying 60 mol% or more, and it is preferable that o-cresol is 70 mol% or more. Also, o-
Cresol is preferably less than 95 mol%,
More preferably, it is at most mol%. If the proportion of o-cresol is less than the above range, the development latitude of the photosensitive composition cannot be widened, while if it exceeds the above range, the solubility in an alkali developer tends to decrease. On the other hand, examples of the remaining phenols include phenol, m-cresol, p-cresol and the like. Phenol accounts for at least 5 mol%, preferably at least 10 mol%, and phenol accounts for at most 30 mol%. This is preferable because the development latitude becomes wider.

Incidentally, when o-cresol is used as a phenol constituting a novolak resin as a binder resin in a conventional positive photosensitive composition for ultraviolet exposure containing an o-quinonediazide group-containing compound or the like, it occupies the same. While the solubility in an alkali developing solution tends to decrease as the proportion increases, it was unsuitable for an alkali developing type positive photosensitive composition,
In the positive photosensitive composition of the present invention containing a photothermal conversion substance and a novolak resin, the novolak resin using o-cresol as a phenol, and at a considerably high ratio, can achieve the object of the present invention. It was completely unexpected.

In the present invention, the novolak resin has a weight average molecular weight of 5,000 to 1 in terms of polystyrene measured by gel permeation chromatography.
5000, preferably 6000 to 120
00 is particularly preferred.

The positive photosensitive composition of the present invention has the above-mentioned photothermal conversion substance and the above-mentioned novolak resin as basic compositions. %, The latter novolak resin is 99.5 to 50% by weight, preferably the former is 1 to 40%.
% By weight, the latter being 99 to 60% by weight, more preferably the former being 2 to 30% by weight, the latter being 98 to 70% by weight, particularly the former being 2 to 10% by weight and the latter being 98 to 90% by weight.
It is particularly preferred that the amount is by weight.

The positive photosensitive composition of the present invention may further comprise, in addition to the photothermal conversion substance and the novolak resin, an alkali-soluble resin other than the novolak resin, such as acrylic acid, as long as the performance of the present invention is not impaired. And / or methacrylic acid as a copolymer component, so-called acrylic resin or the like can be contained. Further, in addition to the photothermal conversion material and the novolak resin, the positive photosensitive composition of the present invention contains the novolak resin for the purpose of increasing the difference in solubility of an exposed part and an unexposed part in an alkali developing solution. Has the function of reducing the solubility of the resin by forming hydrogen bonds with the resin,
Further, a dissolution inhibitor which hardly absorbs light in the near infrared region and is not decomposed by light in the near infrared region may be contained.

Examples of the dissolution inhibitor include sulfonic acid esters, phosphoric acid esters, aromatic carboxylic acid esters, aromatic disulfones, and carboxylic anhydrides described in detail in JP-A-10-268512 by the present applicant. Products, aromatic ketones, aromatic aldehydes, aromatic amines, aromatic ethers, etc.
A lactone skeleton described in detail in No. 3;
An acid-color-forming dye having an N, N-diarylamide skeleton or a diarylmethylimino skeleton and also serving as a colorant; a nonionic surfactant described in detail in Japanese Patent Application No. 10-341400; 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, and more preferably 0 to 30% by weight.
Particularly preferred is 20% by weight.

The positive photosensitive composition of the present invention may have an absorption maximum (λ _max ) of not more than 700 nm, if necessary, to be distinguished from the light-to-heat conversion material, and to have a cation or an anion. Ionic dyes due to non-polarization of, for example, cyanine dyes, pyrylium dyes, thiapyrylium dyes, squarylium dyes, croconium dyes, azurenium dyes, diphenylmethane dyes, triphenylmethane dyes, oxazine dyes, An azine dye, a piologen dye, a xanthene dye, a rhodocyanine dye, a styryl dye, or the like may be contained. Among these, preferred are triphenylmethane dyes having a triphenylmethyl group as a partial structure. I. No. When represented by, for example, C.I.
I. Basic Violet 3 (for example, "Crystal Violet" manufactured by Tokyo Chemical Industry Co., Ltd.), C.I.
I. Basic Blue 5 (for example, “Primocyanine BX conc.” Manufactured by Sumitomo Chemical Co., Ltd.)
etc. ), C.I. I. Basic Blue 7 (for example, “Aizen Victoria Pu” manufactured by Hodogaya Chemical Co., Ltd.)
re Blue BOH "and the like. ), C.I. I. Basic
Blue 26 (for example, “Aiz” manufactured by Hodogaya Chemical Co., Ltd.
en Victoria Blue BH "and the like. ),
C. I. Basic Green 1 (for example, “Aizen Diamond Green” manufactured by Hodogaya Chemical Co., Ltd.)
GH "etc. ), C.I. I. Acid Blue 1 (for example, “Aizen Brillia” manufactured by Hodogaya Chemical Co., Ltd.)
nt Acid Pure Blue VH "and the like. ),
C. I. Solvent Blue 2 (for example, BAS
"Victoria Blue F4R" manufactured by Company F and the like. )
And the like.

The content of the ionic dye in the positive photosensitive composition of the present invention is preferably 0 to 50% by weight, more preferably 0.5 to 30% by weight, and more preferably 1 to 20% by weight. It is particularly preferred that the amount is 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.
Examples of the developability improver preferably include an organic acid having a pKa of 2 or more and an anhydride of the organic acid.

Examples of the organic acid and its anhydride include those described in JP-A-60-88942 and JP-A-63-2760.
48, JP-A-2-96754 and the like, and specifically, glyceric acid, methylmalonic acid, dimethylmalonic acid, propylmalonic acid, succinic acid, malic acid, mesotartaric acid, Glutaric acid, β-methylglutaric acid, β, β-dimethylglutaric acid, β-ethylglutaric acid, β, β-diethylglutaric acid, β-propylglutaric acid, β, β-methylpropylglutaric acid, pimelic acid, suberin Acid, aliphatic saturated carboxylic acid such as sebacic acid, aliphatic unsaturated carboxylic acid such as maleic acid, fumaric acid, glutaconic acid, 1,1-cyclobutanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,1-cyclohexane Pentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,1-cyclohexanedicarboxylic acid, 1,
Carbocyclic saturated carboxylic acids such as 2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexenedicarboxylic acid, 2,3-dihydroxybenzoic acid, 3,
4-dimethylbenzoic acid, 3,4-dimethoxybenzoic acid,
3,5-dimethoxybenzoic acid, p-toluic acid, 2-hydroxy-p-toluic acid, 2-hydroxy-m-toluic acid, 2-hydroxy-o-toluic acid, mandelic acid, gallic acid, phthalic acid, isophthalic acid Acids, carbocyclic unsaturated carboxylic acids such as terephthalic acid, and Meldrum's acid,
Examples thereof include anhydrides such as ascorbic acid, succinic anhydride, glutaric anhydride, maleic anhydride, cyclohexenedicarboxylic anhydride, cyclohexanedicarboxylic anhydride, and phthalic anhydride. Of these, aliphatic dicarboxylic acids are preferred, and alicyclic dicarboxylic acids are more preferred.

The positive photosensitive composition of the present invention is usually prepared by applying the above components to a support in the form of a solution prepared by dissolving the above components in an appropriate solvent, followed by heating and drying. A positive photosensitive lithographic printing plate having a photosensitive composition layer formed on the surface of a support is provided.

Here, the solvent is not particularly limited as long as it has a sufficient solubility for the components used and gives good coating properties, and examples thereof include methyl cellosolve,
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, 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 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 20 to 170 ° C, preferably about 30 to 150 ° C. The drying time is, for example, about 5 seconds to 10 minutes, preferably 10 seconds to
About 5 minutes are taken. For the purpose of improving the contrast during image formation and improving the aging stability of image forming properties, for example, about 40 to 120 ° C., preferably 40 to 70 ° C.
At a temperature of about 5 ° C. for about 5 minutes to 100 hours, preferably 30
It is preferable to perform a heat treatment after about minutes to 75 minutes.

As the support, 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 or aluminum alloy support, and 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 treatment. Is more preferred. As the roughness of the support surface, the average roughness R _a as defined in JIS B0601, usually, 0.3 to 1.0 [mu] m, preferably 0.4
About 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 responds 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
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. The positive photosensitive lithographic printing plate of the present invention can be obtained by developing with an alkali developing solution after the above image exposure.

Examples of the developing solution for use in 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, 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. Here, the content of the alkali metal silicate as silicon dioxide is preferably 0.5 to 10% by weight, more preferably 1 to 8% by weight, and the molar concentration ratio of silicon dioxide to the molar concentration of alkali metal is 0.1 ~
It is preferably 1.5, more preferably 0.3-1. Also, p
H is preferably 12 or more, and the upper limit is preferably 14 or less.
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.

The present invention relates to Japanese Patent Application Laid-Open No. 10-26 filed by the present applicant.
In connection with the improvement of 8512, it is possible to form a positive type image with a very simple system which has a basic composition of a photothermal conversion material and a novolak resin, does not contain a thermally decomposable substance, and cannot expect a chemical change. Some aspects are believed to be based on the same image forming principles as the earlier application. That is, the fact that this image formation is carried out by a change other than a chemical change increases, for example, when the photosensitive composition of the present invention once irradiated with light is heated at about 50 ° C. for 24 hours, immediately after exposure. It can also be inferred from the fact that a reversible phenomenon in which the alkali solubility of the exposed part often returns to a state close to that before exposure is recognized. Furthermore, the glass transition temperature or softening point of the photosensitive composition itself and the susceptibility of its reversible phenomenon to occur in the present invention, it is also recognized that the lower the glass transition temperature or softening temperature, the more easily the reversible phenomenon occurs. It is proof.

The reason why the photosensitive composition of the present invention forms a positive image by such a mechanism is not necessarily clear, but the light energy absorbed by the photothermal conversion substance is converted into heat, and the heat is received. It is considered that the alkali-soluble polymer material in the portion that has undergone a change other than a chemical change such as a conformational change and the alkali solubility of that portion is increased, whereby an image is formed by an alkali developer. The details are described in Japanese Patent Application Laid-Open No. 10-268512 by the present applicant.

[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 1-4, Comparative Examples 1-2 Aluminum plates (0.24 mm thick) were degreased in a 3% by weight aqueous solution of sodium hydroxide at 60 ° C. for 1 minute, and then 1.2% In a 25% by weight aqueous hydrochloric acid solution, at a temperature of 25 ° C,
The electrolytic etching was performed under the conditions of a current density of 80 A / dm ² and a processing time of 10 seconds. Next, after washing with water, a desmut treatment is performed at 50 ° C. for 3 seconds in a 1% by weight aqueous solution of sodium hydroxide, and after washing with water, a temperature of 3% in a 30% by weight sulfuric acid solution.
Anodizing was performed under the conditions of 0 ° C., current density of 10 A / dm ² , and processing time of 15 seconds. Further, hot water sealing treatment was performed with hot water of 90 ° C. and pH 9, washed with water and dried to prepare an aluminum plate for a lithographic printing plate support.

Each coating solution having the composition shown in Table 1 was applied to the surface of the obtained aluminum plate support using a wire bar, dried at 85 ° C. for 3 minutes, and then dried at 55 ° C. for 2 minutes.
By heating and stabilizing for 4 hours, the coating amount is 2.3.
A positive photosensitive lithographic printing plate having a positive photosensitive composition layer of g / m ² was prepared.

The novolak resins in Table 1 represent the following, respectively. A polycondensate of formaldehyde with a mixed phenol of 80 mol% of o-cresol and 20 mol% of phenol (weight average molecular weight 9800). A polycondensate of formaldehyde and a mixed phenol containing 80 mol% of o-cresol and 20 mol% of phenol (weight average molecular weight 7800). Polycondensate of formaldehyde with a mixed phenol containing 80 mol% of o-cresol and 20 mol% of phenol (weight average molecular weight 7200). Polycondensate of formaldehyde with a mixed phenol containing 70 mol% of o-cresol and 30 mol% of phenol (weight average molecular weight 10400). Polycondensate of formaldehyde with a mixed phenol of m-cresol 30 mol%, p-cresol 20 mol%, and phenol 50 mol% (weight average molecular weight 9800, "SK-188" manufactured by Sumitomo Durres Co., Ltd.). Polycondensate of formaldehyde with a mixed phenol of 50% o-cresol and 50% phenol (weight average molecular weight 6200)

For each of the obtained positive photosensitive lithographic printing plates, an exposure apparatus using a semiconductor laser having a wavelength of 830 nm as a light source (“Trend Setter 3” manufactured by Creo Corporation) was used.
244T ") at 160 mJ / cm ² , and then immersed in an alkaline developer (7-fold diluted solution of" DP-4 "manufactured by Fuji Photo Film Co., Ltd.) at 28 ° C. for development. The shortest time and the longest time (however, up to 60 seconds from a practical surface) in which the film was sufficiently removed and the residual film ratio of the non-exposed portion maintained 90% or more were measured, and the development latitude was measured. Was evaluated, and the results are shown in Table 1.

Here, the residual film ratio was calculated based on the following equation by measuring the reflection density using a reflection densitometer (“RD-514” manufactured by Macbeth). Remaining film ratio (%) = [(reflection density of unexposed area after development−reflection density of support surface) / (reflection density of plate surface before development−reflection density of support surface)] × 100

[0078]

[Table 1]

The above-mentioned positive type photosensitive lithographic printing plates are:
When the same development processing as described above is performed after leaving for 10 hours under irradiation of 400 lux light intensity of a white fluorescent lamp (Mitsubishi Electric 36W white fluorescent lamp "Neorumi Super FLR40S-W / M / 36") In each of the Examples and Comparative Examples, there was no substantial film reduction, and the handleability under a white fluorescent lamp was good.

[0080]

According to the present invention, the contrast between the image area and the non-image area is excellent, the development latitude is wide, the residual film ratio of the image area is sufficiently maintained, and more preferably, the light is irradiated with ultraviolet light. A positive photosensitive composition and a positive photosensitive lithographic printing plate which are not sensitive and are excellent in handleability under a white fluorescent lamp.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03F 7/039 501 G03F 7/039 501 H01L 21/027 7/00 503 // G03F 7/00 503 H01L 21/30 502R 502D

Claims (12)

[Claims] 1. A positive photosensitive composition comprising a photothermal conversion substance that absorbs light from an image exposure light source and converts it into heat, and a novolak resin, wherein the composition is an image-sensitive material. The novolak resin does not contain a thermally decomposable substance that is decomposed by the action of heat generated by absorbing light from an exposure light source, and the novolak resin is composed of phenols in which o-cresol accounts for 60 mol% or more. A positive photosensitive composition comprising: 2. A positive photosensitive composition comprising a photothermal conversion material for absorbing light from an image exposure light source and converting it to heat and a novolak resin, and having substantially no sensitivity to light in the ultraviolet region. A positive photosensitive composition, wherein the novolak resin is composed of a phenol in which o-cresol accounts for 60 mol% or more. 3. The positive photosensitive composition according to claim 1, wherein the novolak resin is composed of a phenol in which o-cresol accounts for 70 mol% or more. 4. The positive photosensitive composition according to claim 1, wherein the novolak resin is composed of a phenol having an o-cresol content of 95 mol% or less. 5. The positive photosensitive composition according to claim 1, wherein 5 to 40 mol% of the phenols constituting the novolak resin is phenol. 6. The positive photosensitive composition according to claim 5, wherein the phenol in the phenol constituting the novolak resin is at least 10 mol%. 7. The phenol contained in the phenol constituting the novolak resin is 30 mol% or less.
4. The positive photosensitive composition according to item 1. 8. The weight-average molecular weight of the novolak resin is 50.
The positive photosensitive composition according to any one of claims 1 to 7, wherein the number is from 00 to 15000. 9. The light-to-heat conversion material has a wavelength range of 650 to 130.
The positive photosensitive composition according to any one of claims 1 to 8, which is a light-absorbing dye having an absorption band in part or all of 0 nm. 10. The positive photosensitive composition according to claim 1, which has substantially no sensitivity to light in the ultraviolet region. 11. The composition according to claim 1, wherein the solubility of the composition in an alkali developing solution after standing for 10 hours under a white fluorescent lamp having a light intensity of 400 lux does not substantially change as compared to before the standing. Positive photosensitive composition. 12. A positive photosensitive lithographic printing plate comprising a support and a layer of the positive photosensitive composition according to claim 1 formed thereon.