JP4657783B2 - Image forming material and planographic printing plate precursor - Google Patents

Description

  The present invention relates to an image forming material having a positive photosensitive recording layer. More specifically, the difference in solubility in an alkaline developer between an exposed area and an unexposed area is large, and the plate can be directly made from a digital signal from a computer or the like. The present invention relates to a positive image forming material useful as a lithographic printing plate precursor for infrared laser for so-called direct plate making.

In recent years, the development of lasers has been remarkable, and in particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can easily obtain high-power and small-sized ones. These lasers are very useful as an exposure light source when directly making a plate from digital data such as a computer.
In a known positive photosensitive image forming material for infrared laser for direct plate making, a novolak resin or the like is used as an alkaline aqueous solution-soluble resin.
For example, as a positive type photosensitive image forming material, a substance capable of generating heat by absorbing light, a variety of onium salts, quinonediazide compounds, and the like in an aqueous alkali soluble resin having a phenolic hydroxyl group such as a novolak resin. A positive photosensitive compound, which acts as a dissolution inhibitor that substantially reduces the solubility of the aqueous alkali-soluble resin in the image area, and is heated by heat in the non-image area. There has been disclosed a technique in which an image is formed so that the dissolution inhibiting ability does not appear and can be removed by development (see, for example, Patent Document 1).

Further, the positive photosensitive image forming material is composed of a substance that generates heat by absorbing light and a resin whose alkali aqueous solution solubility is changed by the heat. Low and non-image areas are disclosed in which an aqueous alkali solution becomes highly soluble by heat and can be removed by development to form an image (see Patent Documents 2 and 3).
In the conventional lithographic printing plate precursor, the novolak resin interacts strongly with the dissolution inhibitor, so that the difference in solubility in the developer between the exposed area and the unexposed area becomes large, and the ink acceptability is excellent. For reasons, it is particularly preferably used. For the same reason, novolak resin is also used for positive-type photosensitive image forming materials for infrared lasers. As the novolak resin, a resin obtained by polymerizing phenols such as phenol, cresol and xylenol using formaldehyde under acidic conditions is generally used.

A wide variety of compounds have been studied as dissolution inhibitors, and it is known that onium salt-type dissolution inhibitors exhibit a very strong dissolution inhibitory ability. However, the addition of a general onium salt compound can improve the alkali resistance of the unexposed area due to its high dissolution inhibiting ability, but it has the problem of causing a decrease in sensitivity. As a means for overcoming this problem, a new photosensitive material using a specific onium salt is disclosed (for example, see Patent Document 4). It has been found that onium salts having such a specific structure exhibit excellent characteristics that achieve both high dissolution inhibiting ability and high sensitivity.
However, even in the photosensitive material using the above-described onium salt-type dissolution inhibitor, there is still room for improvement in the interaction releasing property of the exposed portion and the suppression of the remaining film in the non-image portion. There is a demand for a lithographic printing plate precursor that maintains both alkali developability and improves alkali developability in exposed areas, and can obtain a printed image with excellent images regardless of variations in development conditions.
JP-A-7-285275 International Publication No. 97/39894 Pamphlet European Patent Application No. 0823327A2 JP 2002-278050 A

Accordingly, an object of the present invention is a positive type photosensitivity excellent in a difference in solubility in a developer between an exposed area and an unexposed area (dissolvable discrimination: hereinafter referred to as “soluble disk” as appropriate). An object of the present invention is to provide an image forming material and a positive planographic printing plate precursor which are useful as a heat mode compatible positive planographic printing plate precursor having excellent image reproducibility using the composition as a recording layer.

As a result of the study, the present inventors have found that the use of a specific additive in combination can greatly improve the solubility discrepancy, and have completed the present invention.
That is, the image forming material of the present invention comprises (A) an infrared absorber, an iodonium salt, and a sulfonium salt, (B) an onium salt , and ( C) an acid represented by the following general formula (1) on the support. A positive type recording layer containing a color-forming dye and ( D) a water-insoluble and alkali-soluble resin and increasing the alkali-solubility of the exposed portion by infrared exposure is provided.

In the general formula (1), ring A, ring B and ring C each independently represent an aromatic hydrocarbon group or aromatic heterocyclic group having 1 to 3 nuclei, and at least one of ring B and ring C. And at least one substituent selected from the group consisting of an amino group, an alkoxy group, an aryloxy group, an alkylthio group, and an arylthio group. Ring B and ring C may be bonded to each other via a bonding group.
W ¹ represents a carbonyl group, a thiocarbonyl group, or —C (R ⁵ ) ═N—, wherein R ⁵ represents a hydrogen atom or a hydrocarbon group, and Q ¹ represents an oxygen atom, a sulfur atom or an imino group. To express. R ^{1 to} R ⁴ each independently represents a hydrogen atom or a hydrocarbon group. m and n each independently represents 0 or 1.

(C) The mechanism of action for improving the discrimination by addition of the specific acid coloring dye is not clear, but is considered as follows. In the image recording layer according to the present invention, the onium salt selected from (B) iodonium salt and sulfonium salt contained therein has a function of inhibiting dissolution of the photosensitive composition in an alkaline aqueous solution. , the (B) amino group in the onium salt and (C) an acid coloring colorant, an alkoxy group, an aryloxy group, a strong interaction between the functional group such as an alkylthio group and an arylthio group, is formed, which is excellent The film exhibits a dissolution inhibiting effect and forms a strong and excellent development resistance film. On the other hand, such an interaction is not only easily released by exposure or heat, but the acid generated from the onium salt selected from (B) iodonium salt and sulfonium salt decomposed by heat is further converted to (C) acid. The decomposition of the color-forming dye is promoted, and here, the solubility in the developer is remarkably improved by a series of chain decomposition such as the generation of an acid by the decomposition of the acid-color-forming dye and the generation of the acid thereby. Therefore, when such a composition is used as a recording layer of a lithographic printing plate precursor, the unexposed area maintains a strong film excellent in development resistance, and in the exposed area, the interaction is canceled. Due to the generation of chain acid, the solubility in the developer is remarkably improved, and the difference in solubility in the alkaline aqueous developer between the unexposed area and the exposed area (discrimination) is drastically widened, resulting in excellent image reproducibility. Is considered to be expressed.
In the present invention, the color development function by acid decomposition inherent in the acid color-forming dye contained in the recording layer is further enhanced by the effect of the acid generated by the decomposition of the specific onium salt that coexists. The excellent color developability of the part also has the advantage of excellent plate inspection after exposure.

According to the present invention, a positive mode lithographic plate corresponding to a heat mode, which uses a positive photosensitive composition excellent in solubility discrimination as a recording layer, has excellent image reproducibility and good plate inspection after exposure. An image forming material useful as a printing plate precursor and a positive planographic printing plate precursor can be provided.

Hereinafter, the present invention will be described in detail.
The recording layer of the positive type image forming material of the present invention comprises (A) an infrared absorber, (B) an onium salt selected from iodonium salts and sulfonium salts , and ( C) an acid color-forming dye represented by the general formula (1). (Hereinafter, appropriately referred to as (C) acid-coloring dye) and (D) a water-insoluble and alkali-soluble resin is contained as an essential component, and other components are contained as necessary.
Hereinafter, each component contained in the recording layer of the positive type image forming material of the present invention will be described in order. First, the (C) acid coloring dye, which is a characteristic component of the present invention, will be described.

[(C) Acid-coloring dye represented by formula (1)]
The (C) acid color-forming dye used in the present invention is represented by the following general formula (1).

In the general formula (1), ring A, ring B and ring C each independently represent an aromatic hydrocarbon group or aromatic heterocyclic group having 1 to 3 nuclei, and at least one of ring B and ring C. And at least one substituent selected from the group consisting of an amino group, an alkoxy group, an aryloxy group, an alkylthio group, and an arylthio group. Ring B and ring C may be bonded to each other via a bonding group.
W ¹ represents a carbonyl group, a thiocarbonyl group, or —C (R ⁵ ) ═N—, wherein R ⁵ represents a hydrogen atom or a hydrocarbon group, and Q ¹ represents an oxygen atom, a sulfur atom or an imino group. To express. R ^{1 to} R ⁴ each independently represents a hydrogen atom or a hydrocarbon group. m and n each independently represents 0 or 1.

In the acid color-forming dye represented by the general formula (1), as a preferable compound, Q ¹ is an oxygen atom or a sulfur atom, W ¹ is a carbonyl group or a thiocarbonyl group, and ring A is benzene. Ring, piperazine ring, thiophene ring, benzothiophene ring, furan ring, benzofuran ring, indole ring, or pyridine ring, ring B and ring C are each independently a benzene ring or naphthalene ring, and m and n are R ^{1 to} R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 8 carbon atoms, and R ⁵ is a hydrogen atom and 1 carbon atom. An alkyl group having 15 to 15 carbon atoms and an aryl group having 6 to 15 carbon atoms. Among them, Q ¹ is an oxygen atom, W ¹ is a carbonyl group, ring A is a benzene ring, and R ^{1 to} R ⁴ are independently a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. More preferred.

  Moreover, the ring A, the ring B, and the ring C may have a substituent as long as the effects of the present invention are not impaired. Examples of the substituent that can be introduced include a hydroxyl group, a halogen atom, a cyano group, a trimethylsilyloxy group, an alkyl group having 1 to 15 carbon atoms, an acyl group having 2 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and carbon. C1-C15 alkylthio group, C1-C15 alkylsulfinyl group, C1-C15 alkylsulfonyl group, C6-C15 aryloxy group, C6-C15 arylthio group, C2-C2 ˜15 acyloxy group, C2-C15 alkoxycarbonyl group, amino group, and the like. These substituents may further have a substituent as described above. Among these substituents, a hydroxyl group, a chlorine atom, a bromine atom, a trifluoromethyl group, an alkyl group having 1 to 10 carbon atoms, a phenyl group, a tolyl group, an acyl group having 2 to 5 carbon atoms, and an alkyl group having 2 to 5 carbon atoms. An acyloxy group, a dialkylamino group having 1 to 5 carbon atoms, an alkylamino group having 1 to 5 carbon atoms, a phenylamino group, a phenylmethylamino group, an alkoxy group having 1 to 5 carbon atoms, an alkylthio group having 1 to 5 carbon atoms, Those having a phenoxy group, a phenylthio group and the like are preferable.

Ring B and ring C may be bonded to each other via a bonding group. In this case, examples of the bonding group include an oxygen atom, a sulfur atom, a methylene group, and an ethylene group. It is an oxygen atom.
When ring B and ring C are bonded, m and n are both 0, and ring B and ring C are bonded at the o-position to form a 6-membered ring.
In general formula (1), at least one of ring B and ring C has at least one substituent selected from an amino group, an alkoxy group, an aryloxy group, an alkylthio group, and an arylthio group. Is preferably present in each of ring B and ring C, and each may have two or more. Further, those having at least one amino group in each of ring B and ring C are more preferable.
In addition, the substituent selected from the amino group, alkoxy group, aryloxy group, alkylthio group, and arylthio group mentioned here further has a substituent that can be introduced into the ring A, ring B, and ring C described above. It may be.

  As the acid color-forming dye according to the present invention, a compound having two or more acid color-forming dyes represented by the general formula (1), or a plurality of dyes bonded directly or via a bonding group may be used. . As a method of binding a plurality of acid-coloring dyes, any acid-coloring dyes can be used without particular limitation as long as they are bound directly or via a bonding group.

When the compound having a plurality of acid-color-forming dyes is an organic polymer, a compound having a weight average molecular weight (Mw) of 1,000 to 1,000,000, preferably 1,000 to 500,000, more preferably 1,000 to 100,000 is used. Can do. Such an organic polymer substance having a plurality of acid-color-forming dyes has a coating property on its own, and a plurality of acid-color-forming dyes are localized in the molecule. It is preferably used from the viewpoint.
Hereinafter, specific examples of the acid-coloring dyes preferably used in the present invention will be given, but the present invention is not limited thereto.

Among the acid-coloring dyes, it is preferable to use a dye such as a low molecular weight compound having a molecular weight (Mw) of 900 or less from the viewpoint of developability and development residue suppression in the recording layer according to the present invention.
Only 1 type may be used for an acid coloring pigment | dye, and 2 or more types may be used together.
The content of the acid coloring dye is in the range of 1 to 50% by mass, preferably 3 to 40% by mass, more preferably 5 to 25% by mass, based on the total solid content of the components constituting the recording layer. When the acid color-forming dye is an organic polymer (usually weight average molecular weight Mw = 1000 to 100,000), it is 1 to 95% by weight, preferably 3 to 90% by weight, based on the total solid content of the photosensitive composition. Preferably it contains in the range of 5-80 mass%.

[(A) Infrared absorber]
The recording layer of the image forming material of the present invention contains (A) an infrared absorber.
The (A) infrared absorber used in the present invention is not particularly limited as long as it is a substance that absorbs an infrared laser used for recording and generates heat. From the viewpoint of compatibility, an infrared absorbing dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm is preferably mentioned.

[Infrared absorbing dye or pigment]
As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, naphthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, (thio) pyrylium salts And dyes such as metal thiolate complexes, indoaniline metal complex dyes, oxonol dyes, diimonium dyes, aminium dyes, croconium dyes, and intermolecular CT dyes.
Examples of preferable dyes include cyanine dyes described in, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. ,
Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595,
JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60- Naphthoquinone dyes described in Japanese Patent No. 63744
Squarylium dyes described in JP-A-58-112792, etc.,
Cyanine dyes described in British Patent 434,875,
Etc.

  Further, near infrared absorption sensitizers described in US Pat. No. 5,156,938 are also preferably used, and substituted aryl benzoates described in US Pat. No. 3,881,924 are also preferably used. (Thio) pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, JP-A-58-220143 No. 59-41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, JP-A 59-216146 Cyanine dyes described in US Pat. No. 4,283,475, pentamethine thiopyrylium salt described in US Pat. No. 4,283,475, etc. Pyrylium compounds disclosed in JP same 5-19702 are also preferably used.

Moreover, as another example preferable as a dye, the near-infrared absorptive dye described as the formula (I) and (II) in US Patent 4,756,993 can be mentioned.
Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes.

  Furthermore, the dyes represented by the following general formulas (a) to (f) are preferable because of excellent photothermal conversion efficiency, and in particular, the cyanine dye represented by the following general formula (a) is used in the present invention. It is most preferable because it gives high interaction with an alkali-soluble resin, functions as a dissolution inhibitor, and is excellent in stability and economy.

In general formula (a), R ¹ and R ² each independently represents an alkyl group having 1 to 12 carbon atoms, and an alkoxy group, an aryl group, an amide group, an alkoxycarbonyl group, a hydroxyl group, sulfo group on the alkyl group. The substituent may be selected from a group and a carboxyl group. Y ¹ and Y ² each independently represent oxygen, sulfur, selenium, a dialkylmethylene group or —CH═CH—. Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group, which may have a substituent selected from an alkyl group, an alkoxy group, a halogen atom, and an alkoxycarbonyl group, and is adjacent to Y ¹ and Y ² The aromatic ring may be condensed with two consecutive carbon atoms.

In the general formula (a), X represents a counter ion necessary for charge neutralization, and is not necessarily required when the dye cation moiety has an anionic substituent. Q represents a polymethine group selected from a trimethine group, a pentamethine group, a heptamethine group, a nonamethine group or an undecamethine group, and is preferably a pentamethine group, a heptamethine group or a nonamethine group from the viewpoint of wavelength suitability and stability for infrared rays used for exposure, It is preferable in terms of stability to have a cyclohexene ring or a cyclopentene ring containing three consecutive methine chains on any carbon.
In general formula (a), Q is an alkoxy group, aryloxy group, alkylthio group, arylthio group, dialkylamino group, diarylamino group, halogen atom, alkyl group, aralkyl group, cycloalkyl group, aryl group, oxy group, It may be substituted with an iminium base, a group selected from substituents represented by the following general formula (2). Preferred substituents include halogen atoms such as chlorine atoms, diarylamino groups such as diphenylamino groups, phenylthio And arylthio groups such as groups.

In General Formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Y ³ represents an oxygen atom or a sulfur atom.
Of the cyanine dyes represented by the general formula (a), heptamethine cyanine represented by the following general formulas (a-1) to (a-4) is particularly preferable when exposed to infrared rays having a wavelength of 800 to 840 nm. Mention may be made of pigments.

In general formula (a-1), X ¹ represents a hydrogen atom or a halogen atom. R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring. Alternatively, it is particularly preferable that a 6-membered ring is formed.
In general formula (a-1), Ar ¹ and Ar ² may be the same or different, and each represents an aromatic hydrocarbon group that may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Za ⁻ represents a counter anion necessary for charge neutralization, and Za ⁻ is not necessary when the dye has an anionic substituent in its structure and charge neutralization is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a tetrachlorate ion, in view of the storage stability of the recording layer coating solution. Fluoroborate ion, hexafluorophosphate ion, and sulfonate ion. The heptamethine dye represented by the general formula (a-1) can be suitably used for a positive type image forming material, and in particular, a so-called interaction release type positive photosensitive material combined with an alkali-soluble resin having a phenolic hydroxyl group. Is preferably used.

In general formula (a-2), R ¹ and R ² each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and R ¹ and R ² are bonded to each other to form a ring structure. The ring to be formed is preferably a 5-membered ring or a 6-membered ring, and a 5-membered ring is particularly preferable. Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Preferred substituents on the aromatic hydrocarbon group include hydrocarbon groups having 12 or less carbon atoms, halogen atoms, alkoxy groups having 12 or less carbon atoms, alkoxycarbonyl groups, alkylsulfonyl groups, and halogenated groups. An alkyl group etc. are mentioned, An electron withdrawing substituent is especially preferable. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. R ⁹ and R ¹⁰ may be the same or different and each may have a substituent, an aromatic hydrocarbon group having 6 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, a hydrogen atom Alternatively, R ⁹ and R ¹⁰ may be bonded to each other to form a ring having the following structure.

As R < ⁹ > and R < ¹⁰ > in general formula (a-2), aromatic hydrocarbon groups, such as a phenyl group, are the most preferable among the above.
X ⁻ is a counter anion necessary for charge neutralization and has the same definition as Za ⁻ in the general formula (a-1).

In general formula (a-3), R ^{1 to} R ⁸ , Ar ¹ , Ar ² , Y ¹ , Y ² and X ⁻ have the same meanings as those in general formula (a-2). Ar ³ represents an aromatic hydrocarbon group such as a phenyl group or a naphthyl group, or a monocyclic or polycyclic heterosphere group containing at least one of nitrogen, oxygen, and sulfur atoms, and is a thiazole type, a benzothiazole type Naphthothiazole series, thianaphtheno-7,6,4,5-thiazole series, oxazole series, benzoxazole series, naphthoxazole series, selenazole series, benzoselenazole series, naphthselenazole series, thiazoline series, 2-quinoline series, 4-quinoline, 1-isoquinoline, 3-isoquinoline, benzimidazole, 3,3-dialkylbenzoindolenin, 2-pyridine, 4-pyridine, 3,3-dialkylbenzo [e] indole , Tetrazole, triazole, pyrimidine, and thiadiazole Heterocyclic group is preferable to be, include the following structures Particularly preferred heterocyclic groups.

In general formula (a-4), R ^{1 to} R ⁸ , Ar ¹ , Ar ² , Y ¹ and Y ² have the same meanings as in general formula (a-2). R ¹¹ and R ¹² may be the same or different and each represents a hydrogen atom, an allyl group, a cyclohexyl group, or an alkyl group having 1 to 8 carbon atoms. Z represents an oxygen atom or a sulfur atom.
Specific examples of the cyanine dye represented by formula (a) that can be preferably used in the present invention include those exemplified below, and paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. And paragraph numbers [0012] to [0038] of JP-A No. 2002-40638 and paragraph numbers [0012] to [0023] of JP-A No. 2002-23360.

In the general formula (b), L represents a methine chain having 7 or more conjugated carbon atoms, the methine chain may have a substituent, and the substituents may be bonded to each other to form a ring structure. Good. Zb ⁺ represents a counter cation. Preferred counter cations include ammonium, iodonium, sulfonium, phosphonium, pyridinium, alkali metal cations (Na ⁺ , K ⁺ , Li ⁺ ) and the like. R ^{9 to} R ¹⁴ and R ^{15 to} R ²⁰ are each independently a hydrogen atom or halogen atom, cyano group, alkyl group, aryl group, alkenyl group, alkynyl group, carbonyl group, thio group, sulfonyl group, sulfinyl group, oxy group Or a substituent selected from amino groups, or a combination of two or three of these, and may be bonded to each other to form a ring structure. Here, in general formula (b), those in which L represents a methine chain having 7 conjugated carbon atoms and those in which R ^{9 to} R ¹⁴ and R ^{15 to} R ²⁰ all represent hydrogen atoms are easily available. It is preferable from the viewpoint of effect.
Specific examples of the dye represented by formula (b) that can be suitably used in the present invention include those exemplified below.

In general formula (c), Y ³ and Y ⁴ each represent an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom. M represents a methine chain having 5 or more conjugated carbon atoms. R ^{21 to} R ²⁴ and R ^{25 to} R ²⁸ may be the same or different, and are each a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a carbonyl group, a thiol group, Represents a group, a sulfonyl group, a sulfinyl group, an oxy group, or an amino group. Further, wherein Za ^- include a counter anion, Za in the general formula (a-1) ^- synonymous.
In the present invention, specific examples of the dye represented by formula (c) that can be suitably used include those exemplified below.

In general formula (d), R ^{29 to} R ³² each independently represent a hydrogen atom, an alkyl group, or an aryl group. R ³³ and R ³⁴ each independently represents an alkyl group, a substituted oxy group, or a halogen atom. n and m each independently represent an integer of 0 to 4. R ²⁹ and R ³⁰ , or R ³¹ and R ³² may be bonded to each other to form a ring, and R ²⁹ and / or R ³⁰ is R ³³ and R ³¹ and / or R ³² is R ³⁴ taken together, may form a ring, further, when R ³³ or R ³⁴ there are a plurality, R ³³ or between R ³⁴ each other may be bonded to each other to form a ring. X ² and X ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Q is a trimethine group or a pentamethine group which may have a substituent, and may form a ring structure together with a divalent organic group. Zc ⁻ represents a counter anion and has the same meaning as Za ⁻ in the general formula (a-1).
In the present invention, specific examples of the dye represented by the general formula (d) that can be suitably used include those exemplified below.

In the general formula (e), R ^{35 to} R ⁵⁰ each independently represent a hydrogen atom or a substituent, which may have a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a hydroxyl group, A carbonyl group, a thio group, a sulfonyl group, a sulfinyl group, an oxy group, an amino group, and an onium salt structure are shown. M represents two hydrogen atoms or metal atoms, a halometal group, and an oxymetal group, and the metal atoms contained therein include IA, IIA, IIIB, IVB group atoms of the periodic table, first, second, second Three-period transition metals and lanthanoid elements may be mentioned, among which copper, nickel, magnesium, iron, zinc, tin, cobalt, aluminum, titanium, and vanadium are preferable, and vanadium, nickel, zinc, and tin are particularly preferable. These metal atoms may be bonded to an oxygen atom, a halogen atom or the like in order to make the valence appropriate.
In the present invention, specific examples of the dye represented by formula (e) that can be suitably used include those exemplified below.

In the general formulas (f-1) and (f-2), R ^{51 to} R ⁵⁸ each independently represent a hydrogen atom or an alkyl group or an aryl group that may have a substituent. X ⁻ has the same meaning as in general formula (a-2).
In the present invention, specific examples of the dyes represented by formulas (f-1) and (f-2) that can be suitably used include those exemplified below.

  Other photothermal conversion agents include dyes having a plurality of chromophores described in JP-A-2001-242613, JP-A-2002-97384, and U.S. Pat. No. 6,124,425. Suitable are pigments in which a chromophore is covalently linked to a molecular compound, an anionic dye described in US Pat. No. 6,248,893, a dye having a surface orientation group described in JP-A-2001-347765, etc. Can be used.

Examples of the pigment used as the photothermal conversion agent in the present invention include commercially available pigments and Color Index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technical Association, published in 1977), “Latest Pigment Applied Technology”. (CMC Publishing, published in 1986) and “Printing Ink Technology”, published by CMC Publishing, published in 1984).
Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle diameter of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, particularly 0.1 μm, from the viewpoint of the uniformity of the recording layer and the dispersion stability. It is preferable to be in the range of ~ 1 μm.

  As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

The dye or pigment used may be a single compound or a combination of two or more compounds.
These pigments or dyes are 0.01 to 50% by mass, preferably 0.1 to 10% by mass, based on the total solid content constituting the recording layer, from the viewpoint of balance between sensitivity, stability and uniformity. In the case of a dye, it is particularly preferably 0.5 to 10% by mass, and in the case of a pigment, it is particularly preferably 0.1 to 10% by mass.

[(B) Onium salt selected from iodonium salt and sulfonium salt]
The recording layer of the image forming material according to the present invention contains an onium salt selected from iodonium salts and sulfonium salts . Even wonder if it is preferably iodonium salt.
The onium salt that generates radicals by exposure to light having a wavelength that can be absorbed by the infrared absorber (A) used in the present invention is the wavelength of light that is absorbed by the infrared absorber that is the component (A) used in combination. is not particularly limited as long as it can generate radicals in the exposure, preferably onium salt used, iodonium salts, scan sulfonium salt is selected, reactivity and recording of the radicals generated with reduction additives An iodonium salt is particularly preferable from the viewpoint of the stability of the material. The onium salt suitably used in the present invention is an onium salt represented by the following general formula (1) and general formula (3).

In formula (1), Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a group having 12 or less carbon atoms. An aryloxy group is mentioned. Z ¹¹⁻ represents a counter ion selected from the group consisting of a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, preferably a perchlorate ion, a hexafluorophosphate An ion, and an aryl sulfonate ion .
In the formula (3), R ³¹ , R ³² and R ³³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. Z ^31- represents a counter ion having the same ^meaning as Z ^11- .
Particularly preferred sulfonium salts that can be used in the present invention include sulfonium salts represented by the following general formula (4).

In the formula (4), R ⁴¹ , R ⁴² and R ⁴³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms.
(Z ⁴¹ ) ⁻ represents a strong acid residue. Examples of such strong acid residues include residues such as halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), sulfonic acid compounds, carboxylic acid compounds, and inorganic acid compounds. Such a compound preferably has a pKa <5. Suitable inorganic strong acid residues are halide anions, HSO ₄ ⁻ , and halogen-containing complex anions such as tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, and hexafluoroantimonate. Preferably, an inorganic acid compound containing a fluorine atom is used. Specific examples of the inorganic acid compound containing a fluorine atom include, for example, tetrafluoroboric acid, tetrafluoroaluminic acid, tetrafluoroiron acid, tetrafluorogallic acid, hexafluorophosphoric acid, hexafluoroarsenic acid, hexafluoroantimonic acid, Hexafluorosilicic acid, hexafluoronickic acid, hexafluorotitanic acid, hexafluorozirconic acid and the like can be mentioned, and among them, hexanelurophosphoric acid, tetrafluoroboric acid, hexafluoroantimonic acid and the like are preferable.
Among these, benzoyl formic acid, acetic acid, and benzoic acid are particularly preferable.

  Specific examples of the sulfonium salt represented by the general formula (4) that can be suitably used in the present invention [Exemplary compounds (1) to (101)] are listed below, but the present invention is not limited thereto. Absent.

Specific examples of the iodonium salts ([OI-1] to [OI-24] ) represented by the general formula (1) that can be suitably used in the present invention are given below.

The onium salt selected from iodonium salts and sulfonium salts used in the present invention preferably has a maximum absorption wavelength of 400 nm or less, and more preferably 360 nm or less. By setting the absorption wavelength in the ultraviolet region in this way, the image forming material can be handled under white light.

Only 1 type may be used for the onium salt compound chosen from an iodonium salt and a sulfonium salt , and it may use 2 or more types together.
These onium salts are used in an amount of 0.1 to 50% by mass, preferably 0.5 to 40%, based on the total solid content of the composition constituting the recording layer of the image forming material, from the viewpoints of sensitivity and dirtiness of the non-image area. It can be added in a proportion of 1% by mass, particularly preferably 1 to 30% by mass.

[(D) Water-insoluble and alkali-soluble resin]
The recording layer according to the present invention (D) water-insoluble and alkali-soluble resin (hereinafter, appropriately referred to as an alkali-soluble resin) Ru with. The alkali-soluble resin includes a homopolymer containing an acidic group in the main chain and / or side chain in the polymer, a copolymer thereof, or a mixture thereof.
Among these, those having the acidic groups listed in the following (1) to (6) in the main chain and / or side chain of the polymer are preferable from the viewpoint of solubility in an alkaline developer and expression of dissolution inhibiting ability.

(1) Phenol group (-Ar-OH)
(2) Sulfonamide group (—SO ₂ NH—R)
(3) Substituted sulfonamide acid group (hereinafter referred to as “active imide group”)
[—SO ₂ NHCOR, —SO ₂ NHSO ₂ R, —CONHSO ₂ R]
(4) Carboxylic acid group (—CO ₂ H)
(5) Sulfonic acid group (—SO ₃ H)
(6) Phosphate group (—OPO ₃ H ₂ )

  In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrogen atom or a hydrocarbon group which may have a substituent. .

  Among the alkali-soluble resins having an acidic group selected from the above (1) to (6), an alkali-soluble resin having (1) a phenol group, (2) a sulfonamide group, and (3) an active imide group is preferable, An alkali-soluble resin having (1) a phenol group or (2) a sulfonamide group is most preferred from the viewpoint of sufficiently ensuring solubility in an alkaline developer, development latitude, and film strength.

As alkali-soluble resin which has an acidic group chosen from said (1)-(6), the following can be mentioned, for example.
(1) Examples of the alkali-soluble resin having a phenol group include a condensation polymer of phenol and formaldehyde, a condensation polymer of m-cresol and formaldehyde, a condensation polymer of p-cresol and formaldehyde, m− / p. A novolak resin such as a condensation polymer of mixed cresol and formaldehyde, a condensation polymer of phenol and cresol (any of m-, p-, or m- / p-mixing) and formaldehyde, and pyrogallol and acetone Can be mentioned. Furthermore, the copolymer which copolymerized the compound which has a phenol group in a side chain can also be mentioned. Alternatively, a copolymer obtained by copolymerizing a compound having a phenol group in the side chain can also be used.

  Examples of the compound having a phenol group include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, and hydroxystyrene having a phenol group.

  (2) As the alkali-soluble resin having a sulfonamide group, for example, a polymer composed of a minimum constituent unit derived from a compound having a sulfonamide group as a main constituent can be mentioned. Examples of the compound as described above include compounds having at least one sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom and one or more polymerizable unsaturated groups in the molecule. Among them, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group in the molecule is preferable. For example, the following general formula (i) to general formula ( and a compound represented by v).

[Wherein, X ¹ and X ² each independently represent —O— or —NR ⁷ . R ¹ and R ⁴ each independently represents a hydrogen atom or —CH ₃ . R ² , R ⁵ , R ⁹ , R ¹² , and R ¹⁶ each independently represent a C 1-12 alkylene group, cycloalkylene group, arylene group, or aralkylene group that may have a substituent. . R ³ , R ⁷ and R ¹³ each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. R ⁶ and R ¹⁷ each independently represents a C 1-12 alkyl group, cycloalkyl group, aryl group or aralkyl group which may have a substituent. R ⁸ , R ¹⁰ and R ¹⁴ each independently represent a hydrogen atom or —CH ₃ . R ¹¹ and R ¹⁵ each independently represent a C 1-12 alkylene group, cycloalkylene group, arylene group or aralkylene group which may have a single bond or a substituent. Y ¹ and Y ² each independently represent a single bond or CO. ]

  Among the compounds represented by the general formula (i) to the general formula (v), in the positive planographic printing plate precursor of the present invention, in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide N- (p-aminosulfonylphenyl) acrylamide and the like can be preferably used.

  (3) As an alkali-soluble resin having an active imide group, for example, a polymer composed of a minimum constituent unit derived from a compound having an active imide group as a main constituent can be mentioned. Examples of the compound as described above include compounds each having one or more active imide groups represented by the following structural formula and polymerizable unsaturated groups in the molecule.

  Specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

(4) As an alkali-soluble resin having a carboxylic acid group, for example, a minimum structural unit derived from a compound having at least one carboxylic acid group and polymerizable unsaturated group in the molecule is used as a main constituent component. A polymer can be mentioned.
(5) As the alkali-soluble polymer having a sulfonic acid group, for example, a minimum structural unit derived from a compound having at least one sulfonic acid group and a polymerizable unsaturated group in the molecule is a main structural unit. Can be mentioned.
(6) As an alkali-soluble resin having a phosphate group, for example, a minimum structural unit derived from a compound having at least one phosphate group and a polymerizable unsaturated group in the molecule is used as a main constituent component. A polymer can be mentioned.

  The minimum constitutional unit having an acidic group selected from the above (1) to (6) constituting the alkali-soluble resin used for the positive recording layer is not particularly limited to one kind, and is the minimum having the same acidic group. Two or more kinds of structural units or two or more kinds of minimum structural units having different acidic groups may be copolymerized.

  The copolymer preferably contains 10 mol% or more of a compound having an acidic group selected from (1) to (6) to be copolymerized, and is contained in an amount of 20 mol% or more. Those are more preferred. If it is less than 10 mol%, the development latitude tends to be insufficiently improved.

In this invention, when copolymerizing a compound and using an alkali-soluble resin as a copolymer, the other compound which does not contain the acidic group of said (1)-(6) can also be used as a compound to copolymerize. Examples of other compounds not containing an acidic group of (1) to (6) include the compounds listed in the following (m1) to (m12), but are not limited thereto.
(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, and glycidyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.

(M5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(M6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(M7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene.
(M8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(M9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(M10) N-vinylpyrrolidone, acrylonitrile, methacrylonitrile and the like.
(M11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.
(M12) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.

  The alkali-soluble resin preferably has a phenolic hydroxyl group from the viewpoint of excellent image-forming properties when exposed to infrared laser or the like. For example, a phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- Preferred are novolak resins such as / p-mixed cresol formaldehyde resin and phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resin and pyrogallol acetone resin.

  Further, as an alkali-soluble resin having a phenolic hydroxyl group, as described in US Pat. No. 4,123,279, a carbon number of 3 such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin is used. And a condensation polymer of phenol and formaldehyde having an alkyl group of ˜8 as a substituent.

  The alkali-soluble resin preferably has a weight average molecular weight of 500 or more from the viewpoint of image forming properties, and more preferably 1,000 to 700,000. The number average molecular weight is preferably 500 or more, and more preferably 750 to 650,000. The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.

Moreover, these alkali-soluble resins may be used alone or in combination of two or more. In the case of combination, it has 3 to 8 carbon atoms such as a condensation polymer of t-butylphenol and formaldehyde or a condensation polymer of octylphenol and formaldehyde as described in US Pat. No. 4,123,279. A polycondensation product of phenol and formaldehyde having an alkyl group as a substituent, an alkali having a phenol structure having an electron-withdrawing group on an aromatic ring described in JP-A-2000-241972 previously filed by the present inventors A soluble resin or the like may be used in combination.

  When an alkali-soluble resin is used in the present invention, from the viewpoint of sensitivity, image formability, and durability of the coating, 30 to 98% by mass is preferable in the total solid content of the composition constituting the recording layer, and 40 to 95% by mass. % Is more preferable.

[Other ingredients]
The recording layer of the image forming material of the present invention can further contain various additives as required.
For example, a substance that is thermally decomposable, such as an o-quinonediazide compound, an aromatic sulfone compound, and an aromatic sulfonic acid ester compound, and that substantially reduces the solubility of the alkaline water-soluble polymer compound in a state where it does not decompose is used in combination. Is preferable in terms of improving the dissolution inhibition of the image portion in the developer.

  Suitable quinonediazides include o-quinonediazide compounds. The o-quinonediazide compound used in the present invention is a compound having at least one o-quinonediazide group, which increases alkali solubility by thermal decomposition, and compounds having various structures can be used. That is, o-quinonediazide helps the solubility of the sensitive material system by both the effect of losing the ability to suppress the dissolution of the binder due to thermal decomposition and the change of o-quinonediazide itself into an alkali-soluble substance. Examples of the o-quinonediazide compound used in the present invention include J. Although the compounds described in pages 339 to 352 of “Light-Sensitive Systems” (John Wiley & Sons. Inc.) by Korser can be used, they are particularly reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. -Sulfonic acid esters or sulfonic acid amides of quinonediazides are preferred. Further, benzoquinone (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide- described in U.S. Pat. Nos. 3,046,120 and 3,188,210. Esters of 5-sulfonic acid chloride and phenol-formaldehyde resin are also preferably used.

Further, esters of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride with phenol formaldehyde resin or cresol-formaldehyde resin, naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and pyrogallol-acetone resin Similarly, the esters are also preferably used. Other useful o-quinonediazide compounds are reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802, JP-A-48-63803, JP-A-48-96575, JP-A-49-38701, JP-A-48-13354, Japanese Patent Publication Nos. 41-11222, 45-9610, 49-17482, U.S. Pat. Nos. 2,797,213, 3,454,400, and 3,544 No. 323, No. 3,573,917, No. 3,674,495, No. 3,785,825, British Patent No. 1,227,602, No. 1,251,345, No. No. 1,267,005, No. 1,329,888, No. 1,330,932, German Patent No. 854,890 and the like. .
The addition amount of the o-quinonediazide compound is preferably in the range of 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass with respect to the total solid content of the image forming material. These compounds can be used alone, but may be used as a mixture of several kinds.
The addition amount of additives other than the o-quinonediazide compound is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass with respect to the total solid content of the image forming material. is there. In addition, it is preferable to make the additive and binder in this invention contain in the same layer.

  Further, for the purpose of further improving sensitivity, cyclic acid anhydrides, phenols, and organic acids can be used in combination. Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endooxy-Δ4-tetrahydrophthalic anhydride described in US Pat. No. 4,115,128, Tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4'-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ', 4 ″ -Trihydroxytriphenylmethane, 4,4 ′, 3 ″, 4 ″ -tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane and the like. There are sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphoric acid esters, carboxylic acids, and the like, which are described in Japanese Laid-Open Patent Publication No. 60-88942 and Japanese Patent Application Laid-Open No. 2-96755. , P-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate Phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1, Examples thereof include 2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid, etc. The ratio of the cyclic acid anhydride, phenols and organic acids in the image forming material is 0.05-20. % By mass is preferable, more preferably 0.1 to 15% by mass, and particularly preferably 0.1 to 10% by mass.

Further, in the recording layer coating solution of the image forming material of the present invention, as described in JP-A Nos. 62-251740 and 3-208514, in order to broaden the stability of processing with respect to development conditions. Nonionic surfactants, amphoteric surfactants as described in JP-A-59-121044, JP-A-4-13149, siloxane compounds as described in EP950517, A fluorine-containing monomer copolymer as described in JP-A-11-288093 can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like. Specific examples of the double-sided activator include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Co., Ltd.).

The siloxane compound is preferably a block copolymer of dimethylsiloxane and polyalkylene oxide. Specific examples include DBE-224, DBE-621, DBE-712, DBP-732, DBP-534, manufactured by Chisso Corporation. And polyalkylene oxide-modified silicones such as Tego Glide 100 manufactured by Tego, Germany.
The proportion of the nonionic surfactant and the amphoteric surfactant in the image forming material is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass.

In the recording layer of the present invention, a print-out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant can be added.
Typical examples of the printing-out agent include a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt. Specifically, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A-50-36209 and JP-A-53-8128, 36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440, and trihalomethyl compounds and salt-forming organic dyes Can be mentioned. Such trihalomethyl compounds include oxazole-based compounds and triazine-based compounds, both of which have excellent temporal stability and give clear printout images.

  As the image colorant, other dyes can be used in addition to the aforementioned salt-forming organic dyes. Examples of suitable dyes including salt-forming organic dyes include oil-soluble dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (oriental chemical industry) Manufactured by Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), and the like. The dyes described in JP-A-62-293247 are particularly preferred. These dyes can be added to the image forming material at a ratio of 0.01 to 10% by mass, preferably 0.1 to 3% by mass, based on the total solid content of the image forming material.

Furthermore, a plasticizer is added to the image forming material of the present invention as needed in order to impart flexibility of the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid These oligomers and polymers are used.
In addition to these, epoxy compounds, vinyl ethers, and further, phenol compounds having a hydroxymethyl group, phenol compounds having an alkoxymethyl group, and the present inventors described in JP-A-8-276558, A crosslinkable compound having an alkali dissolution inhibiting action described in JP-A-11-160860 proposed in JP-A-11-160860 can be appropriately added depending on the purpose.

  The image forming material of the present invention is formed by forming the recording layer on a suitable support, and can be applied to various uses such as a lithographic printing plate precursor, a color proof, and a display material. It is useful as a lithographic printing plate precursor for heat mode capable of direct plate making by exposure. Hereinafter, the image forming material of the present invention will be described in detail by taking a lithographic printing plate precursor as a representative example as an example.

[Lithographic printing plate precursor]
Specific embodiments will be described below by giving an example in which the image forming material of the present invention is applied to a lithographic printing plate precursor.
[Recording layer (image forming layer)]
The lithographic printing plate precursor to which the image forming material of the present invention is applied can be produced by dissolving the photosensitive layer (image forming layer) coating solution component in a solvent and coating the solution on a suitable support. Further, depending on the purpose, a protective layer, a resin intermediate layer, a backcoat layer, and the like can be formed in the same manner.
Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and toluene. It is not limited. These solvents are used alone or in combination.
The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass.

Further, the coating amount (solid content) on the support obtained after coating and drying varies depending on the use, but generally speaking, 0.5 to 5.0 g / m ² for the recording layer of the lithographic printing plate precursor. preferable. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the recording layer decrease.
The recording layer may be a single layer or may have a multilayer structure.

Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
In the recording layer of the present invention, a surfactant for improving the coating property, for example, a fluorine-based surfactant described in JP-A No. 62-170950 can be added. A preferable addition amount is 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass in the total solid content of the recording layer.

(Resin intermediate layer)
The lithographic printing plate precursor can be provided with a resin intermediate layer between the recording layer and the support, if necessary.
By providing this resin intermediate layer, the recording layer which is an infrared sensitive layer whose solubility in an alkaline developer is improved by exposure, the sensitivity to the infrared laser is good by being provided on the exposed surface or in the vicinity thereof, A resin intermediate layer made of a polymer exists between the support and the infrared sensitive layer, functions as a heat insulation layer, and heat generated by infrared laser exposure does not diffuse to the support and can be used efficiently for image formation Therefore, there is an advantage that the sensitivity can be increased. In the unexposed area, the recording layer itself that is impermeable to the alkali developer functions as a protective layer for the resin intermediate layer, so that the development stability is good and the image is excellent in discrimination. In the exposed area, the components of the recording layer whose dissolution inhibiting ability has been released are quickly dissolved and dispersed in the developer. Since this resin intermediate layer itself that is adjacent to the support is made of an alkali-soluble polymer, it has good solubility in a developer, for example, even when a developer with reduced activity is used. It is considered that this resin intermediate layer is useful because it dissolves quickly without generating a film and the like and contributes to improvement of developability.

[Support]
The support used in the present invention is a dimensionally stable plate, for example, paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), metal plate (for example, aluminum). , Zinc, copper, etc.), plastic films (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), Examples include paper or plastic film on which a metal as described above is laminated or vapor-deposited.
The support according to the present invention is preferably a polyester film or an aluminum plate, particularly when used for a lithographic printing plate precursor. Among them, an aluminum plate is particularly preferable because of its good dimensional stability and relatively low cost. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of different elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10% by mass. Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements.

Thus, the composition of the aluminum plate applied to the image forming material of the present invention is not specified, and a conventionally known aluminum plate can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.
Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used. The roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization treatment if desired in order to enhance the water retention and wear resistance of the surface. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm ^2. A voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable. When the amount of the anodized film is less than 1.0 g / m ² , the printing durability is insufficient, or the non-image portion of the planographic printing plate is easily damaged, and the ink adheres to the damaged portion during printing. So-called “scratch stains” easily occur. After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary. Examples of the hydrophilization treatment used in the present invention include U.S. Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902. There is an alkali metal silicate (eg, aqueous sodium silicate) method as disclosed in US Pat. In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and U.S. Pat. Nos. 3,276,868, 4,153,461, 4,689, A method of treating with polyvinylphosphonic acid as disclosed in the specification of No. 272 is used.

The lithographic printing plate precursor to which the present invention is applied has a positive recording layer provided on a support, and an undercoat layer can be provided between them if necessary.
As an undercoat layer component, various organic compounds are used. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, and phenylphosphone which may have a substituent. Acid, naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, organic phosphonic acid such as methylenediphosphonic acid and ethylenediphosphonic acid, phenylphosphonic acid, naphthylphosphoric acid, alkylphosphoric acid and glycerophosphoric acid optionally having substituents Of organic phosphoric acid such as phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and triethanolamine which may have a substituent Hydroxy groups such as hydrochloride Selected from hydrochloride of the amine to be, but may be used by mixing two or more.

This organic undercoat layer can be provided by the following method. That is, a method in which water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof is dissolved and applied on an aluminum plate and dried, and water, methanol, ethanol, methyl ethyl ketone, etc. In this method, an aluminum plate is immersed in a solution obtained by dissolving the above organic compound in an organic solvent or a mixed solvent thereof to adsorb the above compound, and then washed with water and dried to provide an organic undercoat layer. . In the former method, a solution having a concentration of 0.005 to 10% by mass of the organic compound can be applied by various methods.
In the latter method, the concentration of the solution is 0.01 to 20% by mass, preferably 0.05 to 5% by mass, the immersion temperature is 20 to 90 ° C., preferably 25 to 50 ° C., and the immersion time. Is 0.1 second to 20 minutes, preferably 2 seconds to 1 minute. The solution used for this can be adjusted to a pH range of 1 to 12 with basic substances such as ammonia, triethylamine, potassium hydroxide, and acidic substances such as hydrochloric acid and phosphoric acid. A yellow dye can also be added to improve the tone reproducibility of the image forming material.
The coating amount of the organic undercoat layer is suitably ² to 200 mg / m ² , preferably 5 to 100 mg / m ² . If the coating amount is less than 2 mg / m ² , sufficient printing durability cannot be obtained. Moreover, even if it is larger than 200 mg / m ^2, it is the same.

[Exposure / Development]
The positive lithographic printing plate precursor produced as described above is usually subjected to image exposure and development processing.
As the light source of the light beam used for image exposure, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser or a semiconductor laser is particularly preferable.

As a developer and a replenisher for a lithographic printing plate precursor to which the present invention is applied, conventionally known alkaline aqueous solutions can be used.
For example, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium, and lithium. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are also used. These alkali agents are used alone or in combination of two or more.

Among these alkali agents, particularly preferred developers are aqueous silicate solutions such as sodium silicate and potassium silicate. This is because the developability can be adjusted by the ratio and concentration of silicon oxide SiO ₂ and alkali metal oxide M ₂ O, which are silicate components. For example, Japanese Patent Laid-Open No. 54-62004 An alkali metal silicate as described in JP-B-57-7427 is effectively used.

  Furthermore, when developing using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than that of the developer is added to the developer so that the developer in the developer tank is not changed for a long time. It is known that lithographic printing plate precursors can be processed. This replenishment method is also preferably applied in the present invention.

Various surfactants and organic solvents can be added to the developer and replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area.
Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. If necessary, the developer and replenisher may contain reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids such as sodium salts and potassium salts, organic carboxylic acids, antifoaming agents, and hard water softeners. It can also be added.
The printing plate developed using the developer and the replenisher is post-treated with water-washing water, a rinsing solution containing a surfactant and the like, a desensitizing solution containing gum arabic and starch derivatives. As the post-treatment when the image forming material of the present invention is used as a printing plate, these treatments can be used in various combinations.

  In recent years, automatic developing machines for printing plates have been widely used in the plate making and printing industries in order to rationalize and standardize plate making operations. This automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for transporting the printing plate, each processing liquid tank and a spray device, and each pumped up by a pump while transporting the exposed printing plate horizontally. The processing liquid is sprayed from the spray nozzle and developed. In addition, recently, a method is also known in which a printing plate is dipped and conveyed by a submerged guide roll or the like in a processing liquid tank filled with the processing liquid. In such automatic processing, each processing solution can be processed while being supplemented with a replenisher according to the processing amount, operating time, and the like. In addition, a so-called disposable processing method in which processing is performed with a substantially unused processing solution can also be applied.

  In the present invention, when there is an unnecessary image portion (for example, a film edge mark of the original film) on the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming. The unnecessary image portion is erased. Such erasing is preferably performed by applying an erasing solution to an unnecessary image portion as described in Japanese Patent Publication No. 2-13293, leaving it for a predetermined time, and then washing with water. A method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber as described in JP-A-59-174842 can also be used.

The lithographic printing plate obtained as described above can be subjected to a printing process after applying a desensitized gum if desired. However, if it is desired to obtain a lithographic printing plate with higher printing durability, Processing is performed. In the case of burning a lithographic printing plate, before burning, an adjustment as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 is used. It is preferable to treat with a surface liquid.
As its method, with a sponge or absorbent cotton soaked with the surface-adjusting liquid, it is applied onto a lithographic printing plate, or a method in which the printing plate is immersed and applied in a vat filled with the surface-adjusting liquid, Application by an automatic coater is applied. Further, it is more preferable to make the coating amount uniform with a squeegee or a squeegee roller after coating.

In general, the amount of surface-adjusting solution applied is suitably 0.03 to 0.8 g / m ² (dry mass). The lithographic printing plate coated with the surface-adjusting liquid is dried if necessary, and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). Is done. In this case, the heating temperature and time are in the range of 180 to 300 ° C. and preferably in the range of 1 to 20 minutes, although depending on the type of components forming the image.
The lithographic printing plate that has been burned can be subjected to conventional treatments such as washing and gumming as needed, but a surface-conditioning solution containing a water-soluble polymer compound is used. In such a case, a so-called desensitizing treatment such as gumming can be omitted. The planographic printing plate obtained by such processing is applied to an offset printing machine or the like and used for printing a large number of sheets.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
(Production of support)
Supports A, B, C, and D were prepared by using a JIS-A-1050 aluminum plate having a thickness of 0.3 mm in combination with the following processes.
(A) Mechanical surface roughening treatment While supplying a suspension of abrasive (silica sand) having a specific gravity of 1.12 and water as a polishing slurry liquid to a surface of an aluminum plate, it is mechanically rotated by a roller-like nylon brush. Roughening was performed. The average particle size of the abrasive was 8 μm, and the maximum particle size was 50 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.
(B) Alkali etching treatment The aluminum plate obtained above was sprayed with an aqueous NaOH solution at a temperature of 70 ° C. (concentration 26 mass%, aluminum ion concentration 6.5 mass%) to carry out an etching treatment. ² dissolved. Thereafter, washing with water was performed using well water.

(C) Desmutting treatment Desmutting treatment was performed by spraying with a 1% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.
(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a nitric acid 10.5 g / liter aqueous solution (aluminum ion 5 g / liter) at a temperature of 50 ° C. The AC power supply waveform has an electrochemical surface roughening treatment using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reaches a peak from zero, a DUTY ratio of 1: 1. went. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode.
Thereafter, washing with water was performed using well water.

(E) Alkali etching treatment The aluminum plate was sprayed at a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at 32 ° C. to dissolve the aluminum plate by 0.20 g / m ² , The smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening was used was removed, and the edge portion of the generated pit was melted to smooth the edge portion. Thereafter, washing with water was performed using well water.
(F) Desmut treatment Desmut treatment by spraying was performed with a 15% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (including 4.5% by weight of aluminum ions), and then washed with water using well water. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 7.5 g / liter aqueous solution (containing 5 g / liter of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform was a rectangular wave, and an electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode.
Thereafter, washing with water was performed using well water.
(H) Alkaline etching treatment An aluminum plate is etched by spraying at 32 ° C. with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass, and the aluminum plate is dissolved at 0.10 g / m ² , so The smut component mainly composed of aluminum hydroxide generated during the electrochemical surface roughening treatment was removed, and the edge portion of the generated pit was melted to smooth the edge portion. Thereafter, washing with water was performed using well water.

(I) Desmut treatment A desmut treatment by spraying was performed with a 25% by mass aqueous solution of sulfuric acid at a temperature of 60 ° C. (containing 0.5% by mass of aluminum ions), and then water washing by spraying was performed using well water.
(J) Anodizing treatment As the electrolytic solution, sulfuric acid was used. All electrolytes had a sulfuric acid concentration of 170 g / liter (containing 0.5 mass% of aluminum ions), and the temperature was 43 ° C. Thereafter, washing with water was performed using well water.
Both current densities were about 30 A / dm ² . The final oxide film amount was 2.7 g / m ² .

<Support A>
The steps (a) to (j) were performed in order, and the support was prepared so that the etching amount in the step (e) was 3.4 g / m ² .
<Support B>
Except for omitting the steps (g), (h) and (i) among the above steps, each step was performed in order to prepare a support.
<Support C>
A support was prepared by sequentially performing each step except that the steps (a), (g), (h), and (i) were omitted.
<Support D>
Except for omitting the process of the above step (a) and (d) (e) (f ) performs the steps in turn, supported as total amount of electricity is 450C / dm ² in step (g) The body was made.
Supports A, B, C, and D obtained as described above were subsequently subjected to the following hydrophilization treatment and undercoating treatment.

(K) Alkali metal silicate treatment An alkali metal silica was obtained by immersing the aluminum support obtained by anodizing treatment in a treatment layer of a 1 mass% aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C for 10 seconds. Acid salt treatment (silicate treatment) was performed. Then, the water washing by the spray using well water was performed. The amount of silicate adhering at that time was 3.6 mg / m ² .

(Undercoating)
On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds. The coating amount after drying was 16 mg / m ² .

<Undercoat liquid composition>
・ The following polymer compound 0.3g
・ Methanol 100g
・ Water 1.0g

[Examples 1 to 4, Comparative Examples 1 and 2]
A coating solution for the first layer (lower layer) having the following composition was applied to the obtained support A with a wire bar, and then dried in a drying oven at 150 ° C. for 60 seconds to obtain a coating amount of 0.95 g / m ² . did.
A coating solution for the second layer (upper layer) having the following composition was applied to the obtained support with a lower layer with a wire bar. After coating, drying was carried out at 130 ° C. for 90 seconds in a drying oven, and positive lithographic printing plate precursors of Examples 1 to 4 and Comparative Examples 1 and 2 were prepared with a total coating amount of 1.25 g / m ² .

<First layer (lower layer) coating solution>
-Copolymer 1 (synthesized by the following) 1.833 g
・ Cyanine dye A (the following structure) 0.098g
・ 2-Mercapto-5-methylthio-
1,3,4-thiadiazole 0.030 g
・ Cis-Δ ⁴ -tetrahydrophthalic anhydride 0.100 g
・ 4,4'-sulfonyldiphenol 0.090g
・ 0.008 g of p-toluenesulfonic acid
・ 0.100 g of counter anion of ethyl violet
What changed to 6-hydroxynaphthalenesulfonic acid ・ 3-methoxy-4-diazodiphenylamine 0.030 g
Hexafluorophosphate / fluorine surfactant 0.035g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Γ-Butyrolactone 13.8g

<Synthesis of Copolymer 1>
After stirring, 31.0 g (0.36 mol) of methacrylic acid, 39.1 g (0.36 mol) of ethyl chloroformate and 200 ml of acetonitrile were placed in a 500 ml three-necked flask equipped with a condenser and a dropping funnel, and cooled in an ice-water bath. The mixture was stirred while. To this mixture, 36.4 g (0.36 mol) of triethylamine was dropped with a dropping funnel over about 1 hour. After completion of the dropwise addition, the ice-water bath was removed, and the mixture was stirred at room temperature for 30 minutes.
To this reaction mixture, 51.7 g (0.30 mol) of p-aminobenzenesulfonamide was added, and the mixture was stirred for 1 hour while warming to 70 ° C. in an oil bath. After completion of the reaction, the mixture was added to 1 liter of water with stirring, and the resulting mixture was stirred for 30 minutes. The mixture was filtered to take out a precipitate, which was slurried with 500 ml of water, and then the slurry was filtered, and the obtained solid was dried to dry a white solid of N- (p-aminosulfonylphenyl) methacrylamide. Was obtained (yield 46.9 g).

  Next, 4.61 g (0.0192 mol) of N- (p-aminosulfonylphenyl) methacrylamide and 2.58 g of ethyl methacrylate (0.0258 mol) were added to a 20 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel. ), 0.80 g (0.015 mol) of acrylonitrile and 20 g of N, N-dimethylacetamide were added, and the mixture was stirred while heating to 65 ° C. with a hot water bath. To this mixture, 0.15 g of 2,2′-azobis (2,4-dimethylvaleronitrile) (trade name: “V-65”, manufactured by Wako Pure Chemical Industries, Ltd.) was added as a polymerization initiator and maintained at 65 ° C. The mixture was stirred for 2 hours under a nitrogen stream. This reaction mixture was further mixed with 4.61 g of N- (p-aminosulfonylphenyl) methacrylamide, 2.58 g of methyl methacrylate, 0.80 g of acrylonitrile, 20 g of N, N-dimethylacetamide and 0.15 g of “V-65”. Was dropped by a dropping funnel over 2 hours. After completion of the dropwise addition, the resulting mixture was further stirred at 65 ° C. for 2 hours. After completion of the reaction, 40 g of methanol was added to the mixture, cooled, and the resulting mixture was poured into 2 liters of water while stirring the water. After stirring the mixture for 30 minutes, the precipitate was removed by filtration and dried. 15 g of a white solid was obtained. It was 54,000 when the weight average molecular weight (polystyrene standard) of this specific copolymer 1 was measured by the gel permeation chromatography.

<Second layer (upper layer) coating solution>
・ Ethyl methacrylate and 2-methacryloyloxyethyl succinic acid 0.040 g
Copolymer (molar ratio 75:25, weight average molecular weight 70,000)
Phenol cresol-formaldehyde novolak (phenol: m-cresol: p-cresol = 50: 30: 20,
(Weight average molecular weight: 8800) 0.400 g
・ (B) Onium salt (compound described in Table 1) 0.1 g
-(C) Acid coloring pigment (compound described in Table 1) 0.068 g
・ (A) Cyanine dye A (the above structure) 0.015 g
・ 0.012g of counter anion of ethyl violet
What changed to 6-hydroxynaphthalenesulfonic acid ・ Fluorosurfactant 0.022g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 13.1g
1-methoxy-2-propanol 6.79g

  The acid-color-forming dyes listed in Table 1 below are compounds having the following structures, and the onium salts are compound Nos. 1 and 2 of the exemplified compounds. Represents.

[Evaluation of lithographic printing plate precursor]
The evaluation of the lithographic printing plate precursor was carried out by using the halftone image reproducibility as an index of solubility discrimination and the density of the image area / non-image area as an index of plate inspection. Details of the evaluation method are as follows.
1. Image Reproducibility The positive lithographic printing plate precursors of Examples and Comparative Examples thus obtained were 175 lpi / 2400 dpi / 2% halftone dots under the conditions of beam strength 10.0 W and drum rotation speed 250 rpm on a Trendsetter 3244 manufactured by Creo. Drawing (exposure) was performed on the image of the test pattern.
After exposure under the above conditions, a developer having the following composition and a Fuji Photo Film Co., Ltd. finisher-FP-2W (diluted 1: 1) were used, and Fuji Photo Film Co., Ltd. PS Processor-LP-940H was used. The liquid temperature was kept at 30 ° C., and the development was performed for 12 seconds.
Thereafter, the printing plates of Examples and Comparative Examples were printed with a Heidel KOR-D machine, and after printing 5000 sheets, the halftone dot portion of the obtained printed matter was observed with a magnifying glass of 50 times, and the halftone dot portion was missing. It was confirmed that there was no stain on the part, and image reproducibility was evaluated according to the following criteria. The reproducibility of such a fine halftone dot image greatly depends on the solubility disc. The results are shown in Table 1.
◎: Image reproducibility is very good ○: Image reproducibility is good △: Image part is slightly chipped and non-image part is stained, but there is no practical problem ×: Image reproducibility is poor and practical Problem level

<Alkali developer A composition>
・ SiO ₂ · K ₂ O (K ₂ O / SiO ₂ = 1/1 (molar ratio)) 4.0% by mass
・ Citric acid 0.5% by mass
・ Polyethylene glycol lauryl ether (weight average molecular weight 1,000)
0.5% by mass
・ Water 95.0 mass%

<Alkali developer B composition>
・ D sorbit 2.5% by mass
-Sodium hydroxide 0.85 mass%
・ Polyethylene glycol lauryl ether (weight average molecular weight 1,000)
0.5% by mass
・ Water 96.15% by mass

2. Density evaluation of image area and non-image area Image area (solid image) after standard exposure and development (exposure with a Trendsetter 800 manufactured by Creo, beam intensity 10.0 W, drum rotation speed 250 rpm, development using a developer having the following composition) Part) and non-image part (clear part) were measured with a GRETAG reflection densitometer D196 (manufactured by GretagMacbeth). The greater the density difference between the image area / non-image area, the better the plate inspection. For example, it is evaluated that the contrast between the image part density 2.15 / non-image part density 0.68 is clear and excellent in plate inspection, but the image part density 1.43 / non-image part density 0.68. Therefore, it is difficult to clearly detect the difference between the two visually, and it is evaluated that the plate inspection is inferior. The results are shown in Table 1.

<Evaluation of planographic printing plate precursors of Examples 1 to 4 and Comparative Examples 1 and 2>
About each lithographic printing plate precursor of Examples 1 to 4 and Comparative Examples 1 and 2, the density evaluation and image reproducibility of the image part and the non-image part were evaluated by the above-described methods. Developer B was used as the developer. The results are shown in Table 1.

As shown in Table 1, it can be seen that the lithographic printing plate precursors of Examples 1 to 4 are excellent in image reproducibility and have good solubility discretion. Moreover, the plate inspection after exposure was also excellent. On the other hand, Comparative Example 1 which contains (C) an acid coloring dye but does not contain (B) an onium salt selected from an iodonium salt and a sulfonium salt has a higher image reproducibility than the corresponding Example 1. The density difference between the image area and the non-image area was small, and the plate inspection after exposure was low. In addition, Comparative Example 2 containing only (B) an onium salt and not containing (C) an acid coloring dye has lower image reproducibility than the corresponding Example 3, and contains a coloring dye. From this, it can be seen that the plate inspection after exposure is greatly inferior.

(Examples 5 to 8, Comparative Examples 3 and 4)
A coating solution for the first layer (lower layer) having the following composition was coated on the obtained support C with a wire bar, and then dried in a drying oven at 120 ° C. for 90 seconds to obtain a coating amount of 0.60 g / m ² . did.
A coating solution for the second layer (upper layer) having the following composition was applied to the obtained support with a lower layer with a wire bar. After coating, drying was performed at 120 ° C. for 90 seconds in a drying oven, and positive lithographic printing plate precursors of Examples 5 to 8 and Comparative Examples 3 and 4 were prepared with a total coating amount of 1.35 g / m ² .

<First layer (lower layer) coating solution>
-Copolymer 1 2.200g
・ Cyanine dye A (the above structure) 0.098 g
・ 2-Mercapto-5-methylthio
-1,3,4-thiadiazole 0.030 g
・ Cis-Δ ⁴ -tetrahydrophthalic anhydride 0.100 g
・ 4,4'-sulfonyldiphenol 0.090g
・ 0.008 g of p-toluenesulfonic acid
・ 0.100 g of counter anion of ethyl violet
What changed to 6-hydroxynaphthalenesulfonic acid ・ 3-methoxy-4-diazodiphenylamine 0.030 g
Hexafluorophosphate / fluorine surfactant 0.035g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Dimethylsulfoxide 13.8g

<Second layer (upper layer) coating solution>
・ Ethyl methacrylate and 2-methacryloyloxyethyl succinic acid 0.040 g
Copolymer (molar ratio 70:30, weight average molecular weight 88,000)
Phenol cresol-formaldehyde novolak (phenol: m-cresol: p-cresol = 30: 50: 20,
(Weight average molecular weight: 7700) 0.250 g
-Onium salt (onium compound described in Table 2) 0.02 g
Acid coloring dye (compound described in Table 2) 0.015 g
・ Cyanine dye A (the above structure) 0.015 g
・ Fluorine surfactant 0.022g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 13.1g
1-methoxy-2-propanol 6.79g

<Evaluation of Examples 5 to 8 and Comparative Examples 3 and 4>
The obtained planographic printing plate precursors of Examples 5 to 8 and Comparative Examples 3 and 4 were evaluated in the same manner as in Example 1. Developer B was used as the developer. The results are shown in Table 2.

As shown in Table 2, all of the lithographic printing plate precursors of the examples were excellent in image reproducibility and good dissolution discretion. It can also be seen that the plate inspection after exposure is also excellent. On the other hand, Comparative Example 3 in which (C) an acid color-forming dye was added but (B) an onium salt selected from an iodonium salt and a sulfonium salt was not added has a higher image reproducibility than the corresponding Example 5. It was greatly inferior. Further, the plate inspection property after exposure was low. Comparative Example 4 containing only (B) an onium salt and not containing (C) an acid coloring dye has lower image reproducibility than the corresponding Example 7, and does not contain a coloring dye. From this, it can be seen that the plate inspection after exposure is greatly inferior.

(Examples 9 to 12, Comparative Examples 5 and 6)
A coating solution for the first layer (lower layer) having the following composition was applied to the obtained support D with a wire bar, and then dried in a drying oven at 150 ° C. for 60 seconds to obtain a coating amount of 0.81 g / m ² . did.
A coating solution for the second layer (upper layer) having the following composition was applied to the obtained support with a lower layer with a wire bar. After coating, drying was performed at 120 ° C. for 90 seconds in a drying oven, and positive lithographic printing plate precursors of Examples 9 to 12 and Comparative Examples 5 and 6 were prepared with a total coating amount of 1.1 g / m ² .

<First layer (lower layer) coating solution>
-Copolymer 1 2.133 g
・ Cyanine dye A (the above structure) 0.098 g
・ Cis-Δ ⁴ -tetrahydrophthalic anhydride 0.110 g
・ 4,4'-sulfonyldiphenol 0.090g
・ 0.008 g of p-toluenesulfonic acid
・ 0.100 g of counter anion of ethyl violet
What changed to 6-hydroxynaphthalenesulfonic acid ・ 3-methoxy-4-diazodiphenylamine 0.030 g
Hexafluorophosphate / fluorine surfactant 0.035g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 26.6g
1-methoxy-2-propanol 13.6 g
・ Γ-Butyrolactone 13.8g

<Second layer (upper layer) coating solution>
-Copolymer of ethyl methacrylate and 2-methacryloyloxyethyl succinic acid 0.0350 g
(Molar ratio 65:35, weight average molecular weight 78,000)
-Cresol-formaldehyde novolak (m-cresol: p-cresol = 60: 40, weight average molecular weight: 4100)
0.300g
・ Onium salt (onium compound listed in Table 3) 0.0150 g
Acid coloring pigment (compounds listed in Table 3) 0.012 g
・ Cyanine dye A (the above structure) 0.015 g
・ Fluorine surfactant 0.022g
(Megafuck F-780, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 13.1g
1-methoxy-2-propanol 6.79g

<Evaluation of Examples 9 to 12 and Comparative Example 3>
The obtained lithographic printing plate precursor was evaluated by the method described above. Developer A was used as the developer. The results are shown in Table 3.

As shown in Table 3, all of the lithographic printing plate precursors of Examples 9 to 12 were excellent in image reproducibility and good solubility discretion. It can also be seen that the plate inspection after exposure is also excellent. On the other hand, Comparative Example 5 in which (C) an acid color-forming dye was added but (B) an onium salt selected from an iodonium salt and a sulfonium salt was not used has a higher image reproducibility than the corresponding Example 9. Comparative Example 6 which is greatly inferior, has a low plate inspection property after exposure, and contains only (B) an onium salt and does not contain (C) an acid coloring dye, image reproduction as compared with the corresponding Example 10. It can be seen that the plate inspection after exposure is greatly inferior.
As is clear from Examples 1 to 12, it can be seen that the effects of the present invention can be obtained even if the recording layer prescription is changed.

(Examples 13 to 16, Comparative Examples 7 and 8)
The following recording layer coating solution was applied to the obtained support D and dried at 120 ° C. for 90 seconds to form a recording layer, whereby lithographic printing plate precursors of Examples 13 to 16 and Comparative Examples 7 and 8 were obtained. It was. The coating amount after drying was 1.60 g / m ² .
<Recording layer coating solution>
Phenol cresol-formaldehyde novolak (phenol: m-cresol: p-cresol = 50: 30: 20,
Weight average molecular weight: 6500) 1.0 g
・ Onium salt (onium compounds listed in Table 4) 0.05 g
・ Acid coloring dye (compound described in Table 4) 0.036 g
・ Cyanine dye A (the above structure) 0.05 g
0.01 g of dye having 1-naphthalenesulfonic acid anion as counter anion of Victoria Pure Blue BOH
・ Fluorosurfactant 0.05g
(Megafuck F-177, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 9.0g
・ 9.0 g of 1-methoxy-2-propanol

<Evaluation of Examples 13 to 16 and Comparative Examples 7 and 8>
The obtained lithographic printing plate precursors of Examples 13 to 16 and Comparative Examples 7 and 8 were evaluated in the same manner as in Example 1. Developer A was used as the developer. The results are shown in Table 4.

As shown in Table 4, all of the lithographic printing plate precursors of Examples 13 to 16 were excellent in image reproducibility and good in solubility discretion. It can also be seen that the plate inspection after exposure is also excellent. On the other hand, Comparative Example 7 in which (C) an acid color-forming dye was added but (B) an onium salt selected from an iodonium salt and a sulfonium salt was not added had a higher image reproducibility than the corresponding Example 13. Comparative Example 8 which is greatly inferior, has a low plate inspection property after exposure, and contains only (B) an onium salt and does not contain (C) an acid color-forming dye, is also an image compared to the corresponding Example 13. It can be seen that the reproducibility is low and the plate inspection after exposure is greatly inferior.
Further, in the comparison between Examples 1 to 12 and Examples 13 to 16, it can be seen that the effect of the present invention is similarly exhibited when the recording layer is a single layer or a multilayer.

Claims (5)

On the support, (A) an infrared absorber, (B) an onium salt selected from iodonium salts and sulfonium salts, (C) an acid color-forming dye represented by the following general formula (1), and (D) water-insoluble A positive-type image-forming material comprising a recording layer containing an alkali-soluble resin and increasing the alkali-solubility of the exposed part by infrared exposure.

In the general formula (1), ring A, ring B and ring C each independently represent an aromatic hydrocarbon group or aromatic heterocyclic group having 1 to 3 nuclei, and at least one of ring B and ring C. And at least one substituent selected from the group consisting of an amino group, an alkoxy group, an aryloxy group, an alkylthio group, and an arylthio group. Ring B and ring C may be bonded to each other via a bonding group.
W ¹ represents a carbonyl group, a thiocarbonyl group, or —C (R ⁵ ) ═N—, wherein R ⁵ represents a hydrogen atom or a hydrocarbon group, and Q ¹ represents an oxygen atom, a sulfur atom or an imino group. To express. R ^{1 to} R ⁴ each independently represents a hydrogen atom or a hydrocarbon group. m and n each independently represents 0 or 1.   The positive type image forming material according to claim 1, wherein the (D) water-insoluble and alkali-soluble resin is a novolak resin. The positive image forming material according to claim 1, wherein the sulfonium salt is a compound represented by the following general formula (4).

In the general formula (4), R ⁴¹ , R ⁴² and R ⁴³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent.
(Z ⁴¹ ) ⁻ represents a strong acid residue. The recording layer has a multi-layer structure, and the upper layer is (A) an infrared absorber, (B) an onium salt selected from an iodonium salt and a sulfonium salt, and (C) an acid coloration represented by the following general formula (1). The positive-type image-forming material according to any one of claims 1 to 3 , which is a layer containing a functional dye and (D) a water-insoluble and alkali-soluble resin. On the support, (A) an infrared absorber, (B) an onium salt selected from iodonium salts and sulfonium salts, (C) an acid color-forming dye represented by the following general formula (1), and (D) water-insoluble A positive mode lithographic printing plate precursor for heat mode, comprising a recording layer containing an alkali-soluble resin and increasing the alkali-solubility of the exposed area by infrared exposure.

In the general formula (1), ring A, ring B and ring C each independently represent an aromatic hydrocarbon group or aromatic heterocyclic group having 1 to 3 nuclei, and at least one of ring B and ring C. And at least one substituent selected from the group consisting of an amino group, an alkoxy group, an aryloxy group, an alkylthio group, and an arylthio group. Ring B and ring C may be bonded to each other via a bonding group.
W ¹ represents a carbonyl group, a thiocarbonyl group, or —C (R ⁵ ) ═N—, wherein R ⁵ represents a hydrogen atom or a hydrocarbon group, and Q ¹ represents an oxygen atom, a sulfur atom or an imino group. To express. R ^{1 to} R ⁴ each independently represents a hydrogen atom or a hydrocarbon group. m and n each independently represents 0 or 1.