JP2006258979A - Positive planographic printing original plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive planographic printing original plate having excellent ink receptivity and scratch resistance in an image portion and giving a high-quality image. <P>SOLUTION: The plate has a recording layer on a supporting body, wherein the recording layer comprises a heat-mode compatible positive photosensitive composition containing (A) a photo-thermal converting agent and (B) a sulfonium salt expressed by general formula (1). In formula (1), each of R<SP>1</SP>, R<SP>2</SP>and R<SP>3</SP>independently represents an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group, and at least one of R<SP>1</SP>to R<SP>3</SP>is an alkyl group or a cycloalkyl group; and X<SP>-</SP>represents an acid anion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat mode-compatible lithographic printing plate precursor having a recording layer made of a positive photosensitive composition, and more specifically, it can be directly made from a digital signal of a computer or the like using an infrared laser, etc. The present invention relates to a positive type lithographic printing plate precursor for direct plate making, which has excellent properties and scratch resistance.

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 for making a plate directly from digital data such as a computer.
In a known positive lithographic printing plate precursor 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 such a recording layer, since the main component is an alkali-soluble resin, there is a problem that the strength of the image area is not sufficient and is easily damaged, and a strong dissolution inhibiting ability is provided to improve the strength of the surface. When a compound exhibiting the above was used, the recording sensitivity tended to decrease.

  As a dissolution inhibitor, it is known that an onium salt type dissolution inhibitor exhibits 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 means for overcoming this problem, a photosensitive composition using a specific onium salt has been 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, when such an onium salt is used, there is a problem that the compatibility with the resin becomes too high and the strength of the film is lowered.

  Furthermore, when a positive recording layer is used, in order to form a good ink image on the surface, it is necessary to impart sufficient oleophilicity to the surface of the recording layer, and improve the ink deposition property when squeezed out. Is useful because it leads to a significant increase in work efficiency during printing. However, if the surface is made oleophilic in order to improve the ink inking property, the developer permeability to the photosensitive layer is deteriorated, so that the developability is usually lowered. Therefore, it is preferable to use a material having a balance between hydrophilicity and oleophilicity in order to impart developability and inking property, but a material capable of sufficiently satisfying both hydrophilicity and oleophilicity is obtained. The current situation has not yet been obtained.

As a method for ensuring the lipophilicity of the recording layer, for example, a method using a polymer having a linear, branched or cyclic alkyl group having 4 to 20 carbon atoms such as phenolic hydroxyl group and stearyl group has been proposed (for example, , See Patent Document 5). However, when the above lipophilic polymer is used as the main component of the binder, since the amount added is large, the influence on other properties such as developability is increased, and it is difficult to use it. On the other hand, when such a lipophilic polymer is used in a small amount as an additive, there is a problem in that the effect of improving the ink deposition property as expected cannot be obtained.
JP-A-7-285275 International Publication No. 97/39894 Pamphlet European Patent Application No. 0823327A2 JP 2004-117546 A JP 2004-117882 A

  Accordingly, an object of the present invention is to provide a positive type lithographic printing plate precursor which is excellent in ink depositing property and scratch resistance of an image portion and from which good printed matter can be obtained.

As a result of studies, the present inventors have found that the above object can be achieved by using an onium salt having a specific structure, and have completed the present invention.
That is, the positive type lithographic printing plate precursor according to the present invention comprises a positive photosensitive material containing (A) a photothermal conversion agent and (B) a sulfonium salt represented by the following general formula (1) on a support. It has a recording layer made of the composition, and can be directly recorded from digital data by infrared laser exposure or the like.

In the formula, each of R ¹ , R ² , and R ³ independently represents an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and at least one of R ^{1 to} R ³ is an alkyl group or a cycloalkyl group. It is.
X ⁻ represents a strong acid residue.

Although the mechanism of action of the invention is not clear, it is presumed as follows.
The recording layer in the lithographic printing plate precursor according to the invention is provided by dissolving a sulfonium salt having an alkyl group and an alkali-soluble resin in a coating solvent, and coating and drying on a support. Thereby, as the coating solvent is removed in the drying process, phase separation caused by the incompatibility inherent in the sulfonium salt having an alkyl group and the alkali-soluble resin occurs, and the recording according to the present invention is performed. It is considered that the specific sulfonium salt contained in the layer is unevenly distributed in the recording layer and covers the surface. In the present invention, such uneven surface distribution lowers the frictional force on the surface of the recording layer, and therefore is considered to relieve the stress on scratches and scratches. Further, since the surface uneven distribution of the sulfonium salt is unevenly distributed while the alkyl group is directed outward (surface), it is presumed that the surface becomes hydrophobic and exhibits excellent ink deposition properties. This tendency becomes more prominent as the chain length of the alkyl group becomes longer, and the scratch resistance is further improved.

The positive recording layer of the present invention is “heat mode compatible”. This means that recording by heat mode exposure is possible.
The definition of the heat mode exposure in this invention is explained in full detail. Hans-Joachim Time, IS & Ts NIP 15: 1999 International Conference on Digital Printing Technologies. As described in p209, a light-absorbing substance (for example, a dye) is photoexcited in a photosensitive material and undergoes a chemical or physical change to form a chemical or physical change from the photoexcitation of the light-absorbing substance that forms an image. It is known that there are two modes in the above process. One is that the photo-excited light-absorbing substance is deactivated by some photochemical interaction (for example, energy transfer, electron transfer) with other reactants in the photosensitive material, and as a result, the activated reactant is The so-called photon mode that causes the chemical or physical change necessary for the above-described image formation, and the other is that the photo-excited light-absorbing material generates heat and deactivates, and the reaction material is converted into the above-described using the heat. This is a so-called heat mode that causes a chemical or physical change necessary for image formation. In addition, there are special modes such as ablation that explosively scatters by the energy of light gathered locally, and multiphoton absorption in which one molecule absorbs a large number of photons at once.

  The exposure process using each of the above modes is called photon mode exposure and heat mode exposure. The technical difference between photon mode exposure and heat mode exposure is whether or not the energy amount of several photons to be exposed can be added to the target energy amount of the reaction. For example, consider that a certain reaction is caused by using n photons. In photon mode exposure, photochemical interaction is used, so that one-photon energy cannot be added together due to the requirement of quantum energy and momentum conservation laws. That is, in order to cause some kind of reaction, a relationship of “one photon energy amount ≧ reaction energy amount” is necessary. On the other hand, in heat mode exposure, heat is generated after light excitation, and light energy is converted into heat and used, so that the amount of energy can be added. Therefore, the relationship “energy amount of n photons ≧ energy amount of reaction” is sufficient. However, this energy amount addition is restricted by thermal diffusion. That is, if the next photoexcitation-deactivation process occurs and heat is generated before the heat escapes from the exposed portion (reaction point) of interest now, due to thermal diffusion, the heat is surely accumulated and added, and the temperature of that portion increases. Leads to. However, when the next heat generation is slow, the heat escapes and does not accumulate. In other words, in the heat mode exposure, even when the same total exposure energy amount is used, the result differs depending on whether a high energy amount of light is irradiated for a short time or a low energy amount of light for a long time. It becomes advantageous for accumulation.

Of course, in the photon mode exposure, a similar phenomenon may occur due to the diffusion of the subsequent reactive species, but basically this does not occur.
That is, in terms of the characteristics of the photosensitive material, in the photon mode, the intrinsic sensitivity of the photosensitive material (energy for reaction required for image formation) with respect to the exposure power density (W / cm ² ) (= energy density per unit time). In the heat mode, the intrinsic sensitivity of the photosensitive material increases with respect to the exposure power density. Therefore, when the exposure time is fixed so that the necessary productivity can be maintained in practice as an image recording material, when comparing the modes, the photon mode exposure usually has a high sensitivity of about 0.1 mJ / cm ^2. However, since the reaction occurs at any small exposure amount, the problem of low exposure fogging in the unexposed area is likely to occur. On the other hand, in the heat mode exposure, the reaction does not occur unless the exposure amount is a certain level or more, and usually about 50 mJ / cm ² is required because of the relationship with the thermal stability of the photosensitive material. The problem is avoided.
In fact, in the heat mode exposure, the exposure power density on the plate surface of the photosensitive material needs to be 5000 W / cm ² or more, preferably 10000 W / cm ² or more. However, although not described in detail here, use of a high power density laser of 5.0 × 10 ⁵ W / cm ² or more is not preferable because of problems such as ablation and contamination of the light source.

  According to the present invention, it is possible to obtain a positive lithographic printing plate precursor which is excellent in scratch resistance and ink deposition property of an image portion and can obtain a good printed matter and which can be recorded with an infrared laser.

Hereinafter, the present invention will be described in detail.
The lithographic printing plate precursor according to the invention comprises (A) a photothermal conversion agent and (B) a sulfonium salt represented by the general formula (1) (hereinafter referred to as (B) a specific sulfonium salt as appropriate) in the recording layer. Such a lithographic printing plate precursor can be directly recorded from digital data by infrared laser exposure or the like.
Hereinafter, the components of the positive photosensitive composition contained in the recording layer according to the present invention will be described in detail.

[(B) Sulfonium salt represented by general formula (1)]
The specific sulfonium salt (B) which is a characteristic component of the recording layer according to the present invention is a sulfonium salt compound represented by the following general formula (1).

In the general formula (1), R ¹ , R ² and R ³ each independently represents an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group, and at least one of R ^{1 to} R ³ is an alkyl group. Or it is a cycloalkyl group.
X ⁻ represents a strong acid residue.

The alkyl group in the case in the general formula (1), the R ¹ to R ³ represents an alkyl group, preferably an alkyl group having a carbon number of 1-30, a straight chain alkyl group, branched-chain alkyl group having the cyclic Any of the cycloalkyl groups may be used. These alkyl groups and cycloalkyl groups may further have a substituent.
Among these, a C2-C30 linear alkyl group, a C3-C30 branched alkyl group, and a C5-C25 cyclic alkyl group are more preferable. A linear alkyl group having 5 to 24 carbon atoms and a cyclic alkyl group having 5 to 7 carbon atoms are more preferable, and a linear alkyl group having 6 to 20 carbon atoms is most preferable.
Specific examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, hexadecyl group. , Octadecyl group, eicosyl group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group , Cyclopentyl group, 2-norbornyl group and the like.

Among these, from the viewpoint of improving surface orientation and surface lipophilicity, it is preferably a linear hydrocarbon group having 4 to 30 carbon atoms, more preferably 5 to 24 carbon atoms, and scratch resistance. As a range in which both of the highest level of wearability and inking properties are used, the carbon number of 6 to 20 is most preferable.
Preferable specific examples in that respect include n-butyl group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, 2-cyclohexylethyl group and the like. Can be mentioned.
1. Examples of the substituent that can be introduced into the alkyl group include an amino group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, and an aryloxycarbonylamino group. Group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, hydroxyl group, mercapto group, halogen atom, cyano group, sulfo group, carboxyl group, nitro group, etc. May be further substituted.

In the general formula (1), when R ^{1 to} R ³ represent an aralkyl group, the aralkyl group is preferably an alkyl group having 4 to 14 carbon atoms substituted with an aryl group. Any of the aforementioned linear, branched, and cyclic alkyl groups may be used, and examples of the aryl group include the aryl groups described in detail below. The alkyl group part and the aryl group may further have a substituent.
Specific examples of the aralkyl group include a phenylbutyl group, a phenylpentyl group, a phenylhexyl group, and a phenyloctyl group.
Examples of substituents that can be introduced into the aralkyl group include alkyl groups, aryl groups, alkenyl groups, alkynyl groups, amino groups, alkoxy groups, aryloxy groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, acyloxy groups, acylamino groups, Alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, hydroxyl group, mercapto group, halogen atom, cyano group, sulfo group, carboxyl group, nitro group , Etc., and these may be further substituted.

In general formula (1), when R ^{1 to} R ³ represent an aryl group, the aryl group is an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Group is preferable, and the aryl group may further have a substituent.
Specific examples of the aryl group include a phenyl group, a p-methylphenyl group, and a naphthyl group.
Examples of substituents that can be introduced into the aryl group include alkyl groups, aryl groups, alkenyl groups, alkynyl groups, amino groups, alkoxy groups, aryloxy groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, acyloxy groups, and acylamino groups. , Alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, hydroxyl group, mercapto group, halogen atom, cyano group, sulfo group, carboxyl group, nitro Groups, etc., which may be further substituted.

At least one of R ^{1 to} R ³ needs to be an alkyl group or a cycloalkyl group, and preferably two of R ^{1 to} R ³ are an alkyl group or a cycloalkyl group.

In the general formula (1), X ⁻ represents a strong acid residue. The strong acid residue represented by X ⁻ is preferably an anion corresponding to a conjugate base of any organic acid or inorganic acid, and may be a high molecular compound or a low molecular compound, and may be a polyvalent anion. Good. These anions include R ^a1 —SO ₃ ⁻ , R ^a1 —SO ₂ ⁻ , R ^a1 —CO ₂ ⁻ , R ^a1 —CS ₂ ⁻ , R ^a1 —O—CS ₂ ⁻ , R ^a1 —S—CS _{2. ^{-, R a1 -O-PO 2}} -, (R a1 -O) 2 PO 2 -, R a1 (R a1 -O) PO 2 -, R a1 -EW 1 -Z - -EW 2 -R a1, ( R ^a1 ) ₄ B ⁻ , an anion corresponding to an organic acid conjugate base such as Ar ^x O ⁻ , or F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , ClO ₄ Corresponds to inorganic acid conjugate bases such as ⁻ , SO ₄ ²⁻ , NO ₃ ⁻ , CO ₃ ²⁻ , SCN ⁻ , CN ⁻ , SiF ₆ ⁻ , FSO ₃ ⁻ , I ₃ ⁻ , Br ₃ ⁻ , IBr ₂ ⁻ Anions can be mentioned.
Here, R ^a1 represents an organic substituent, and represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a group further substituted with them. Or may be bonded to each other to form a ring. EW ^{1 to} EW ² represent an electron-withdrawing group, and specific examples include —SO—, —CO—, —SO ₂ —, —CN, and the like. Z represents —CR ^z1 — (R ^z1 represents a hydrogen atom or a substituent), or —N—. Ar ^x represents an aryl group. Z ¹¹⁻ is preferably an anion having at least one substituent having an alkali-dissociable proton. Examples of such a substituent having an alkali dissociable proton include a phenolic hydroxyl group (Ar—OH), a carboxyl group (—COOH), a mercapto group (—SH), a phosphonic acid group (—PO ₃ H ₂ ), phosphorus group (-OPO ₃ H _2), a sulfonamide group _{(-SO 2 NH 2, -SO 2} NHR), substituted sulfonamide-based acid group (hereinafter, referred to as "active imide group".-SO ₂ NHCOR, -SO ₂ NHSO ₂ R, —CONHSO ₂ R), sulfonic acid group (—SO ₃ H), sulfinic acid group (—SO ₂ H), —C (CF ₃ ) ₂ OH, and —COCH ₂ COCF ₃ are preferably used. Here, Ar represents an aryl group which may have a substituent, and R represents a hydrocarbon group which may have a substituent. Examples of a system having a good balance between dissolution inhibiting ability and sensitivity include phenolic hydroxyl group, phosphonic acid group, phosphinic acid group, phosphoric acid group, sulfonamide group, active imide group, -C (CF ₃ ) ₂ OH,- COCH ₂ COCF ₃ can be mentioned, and phenolic hydroxyl group, phosphonic acid group and phosphinic acid group are most preferable.

Moreover, as a physical property, the compound which has the anion part whose hydrophilicity / hydrophobicity parameter logP is less than 2 is mentioned. Here, the log P of the anion moiety refers to the log P of the acid compound when the anion moiety is an acid compound. The new hydrophobic parameter logP of the anion part in the present invention means a common logarithm of the partition coefficient P (Partition Coefficient) of the acid compound when the anion part is an acid compound, and an organic compound is an oil (generally, , 1-octanol) is a physical property value representing how it is distributed in the equilibrium of the two-phase system of water as a quantitative numerical value, and can be obtained by the following equation.
logP = log (Coil / Cwater)
Here, Coil represents the molar concentration in the oil phase, Cwater represents the molar concentration in the aqueous phase, and the greater the log P value is, the more positive the oil solubility is. It turns out that it is excellent in water solubility, so that becomes large. This value has a negative correlation with the water solubility of the organic compound, and is widely used as a parameter for estimating the hydrophilicity / hydrophobicity of the compound. In principle, logP is actually measured in a distribution experiment. However, since the experiment is complicated, it is usually calculated using an online measured value database or calculation software estimated from a structural formula. In the present invention, C.I. Hansch, A.D. LogP value estimation program developed by Leo et al.'S Medchem project and Biobyte: CLOGP (Daylight Chemical Systems system: PCLOGS embedded in PCModels (ver 1.02): Algorithm = 4.01 Fragment database = 17 ) Is used.

  The specific compounds of the present invention are exemplified below by preferred onium cation moieties [1-20] and preferred anion moieties [(1)-(55)]. The combination of these cation parts and anion parts is arbitrary, and if it is an onium salt which has the onium cation part and the anion part which is a strong acid residue as shown below, there will be the effect of this invention.

Among these, the sulfonium salt most preferably used in the present invention comprises a cation moiety in which three linear alkyl groups having 3 to 7 carbon atoms are substituted and an anion moiety having a hydrophilicity / hydrophobicity parameter logP of less than 2. It is a sulfonium salt.
The (B) specific sulfonium salt may be used alone or in combination of two or more.
The compounding amount of these specific sulfonium salts is such that the compounding amount of these specific sulfonium salts is the total solid of the positive photosensitive composition from the viewpoint of the balance between the solubility of the exposed part in the alkali developer and the development resistance of the unexposed part The content is preferably in the range of 0.1 to 50% by mass, more preferably 0.5 to 40% by mass, and most preferably 1 to 30% by mass.

An onium salt other than the specific sulfonium salt can be used in combination in the recording layer of the lithographic printing plate precursor according to the invention. Examples of the onium salt include general sulfonium salts other than the specific sulfonium salts described above, diazonium salts, ammonium salts, phosphonium salts, iodonium salts, selenonium salts, arsonium salts, azinium salts, and the like. Of these, ammonium salts are preferred.
Such an onium salt is not particularly limited as long as it is decomposed by exposure to light having a wavelength that can be absorbed by the (A) photothermal conversion agent used in the present invention, and generates an acid. , Diazonium salts and sulfonium salts are preferred. Such a general onium salt can be used in the range of 0 to 30% by mass, preferably in the range of 0.5 to 15% by mass, with respect to the specific sulfonium salt.

[(A) Photothermal conversion agent]
The positive recording layer according to the present invention contains (A) a photothermal conversion agent.
The (A) photothermal conversion agent used in the present invention is not particularly limited as long as it is a substance that absorbs an infrared laser used for image recording and generates heat. From the viewpoint of compatibility, an infrared-absorbing dye or an infrared-absorbing pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm is preferable.

  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, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, oxonol dyes And dyes such as diimonium dyes, aminium dyes, and croconium dyes.

  Preferred dyes include, for example, cyanine dyes described in 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-60-63744, etc., naphthoquinone dyes, JP-A-58-112792, etc. And cyanine dyes described in British Patent 434,875.

  Also, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is preferably used, and a substituted arylbenzo (thio) pyrylium salt described in US Pat. No. 3,881,924, Trimethine thiapyrylium salts described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363, 59-84248 Nos. 59-84249, 59-146063, 59-146061, pyranlium compounds, cyanine dyes described in JP-A-59-216146, US Pat. No. 4,283,475 The pentamethine thiopyrylium salts described above and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are also preferably used. .

  Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).

  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 (e) are preferable because of their excellent photothermal conversion efficiency. Particularly, the cyanine dyes represented by the following general formula (a) are used in the polymerizable composition of the present invention. In this case, it is most preferable because it gives high polymerization activity and is excellent in stability and economy.

In formula (a), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a carbon atom having 1 to 12 carbon atoms including a hetero atom. Indicates a hydrogen group. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.

In the above formula, Xa ^- has Za described later ^- is defined as in, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and 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 or It is particularly preferable that a 6-membered ring is formed.

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. 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. Furthermore, Za ^- represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (a) 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 hexagonal salt, in view of the storage stability of the recording layer coating solution. Fluorophosphate ions and aryl sulfonate ions.

  Specific examples of the cyanine dye represented by formula (a) that can be suitably used in the present invention include those exemplified below, and paragraph numbers [0017] to [0019] of JP-A-2001-133969. And those described in 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 are bonded to each other to form a ring structure. Also 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 the 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. From the viewpoint of the effect.

  Specific examples of the dye represented by formula (b) that can be suitably used in the present invention include those exemplified below.

In the 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) ^- it is synonymous.

  In the present invention, specific examples of the dye represented by formula (c) that can be suitably used include those exemplified below.

In the 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 represents 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 A ring may be bonded to each other, and when there are a plurality of R ³³ or R ³⁴ , R ³³ or R ³⁴ may be bonded to each other to form a ring. X ¹ and X ² are each independently a hydrogen atom, an alkyl group, or an aryl group, and at least one of X ¹ and X ² represents a hydrogen atom or an alkyl 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, Za in the general formula (a) ^- synonymous.

  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 are each independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a hydroxyl group, or a carbonyl group that may have a substituent. Group, thio group, sulfonyl group, sulfinyl group, oxy group, amino group, and onium salt structure. M represents two hydrogen atoms or metal atoms, a halometal group, and an oxymetal group, and the metal atoms contained therein are IA, IIA, IIIB, IVB group atoms of the periodic table, first, second, second Three-period transition metals and lanthanoid elements can be mentioned, among which copper, magnesium, iron, zinc, cobalt, aluminum, titanium, and vanadium are preferable.

  In the present invention, specific examples of the dye represented by formula (e) that can be suitably used include those exemplified below.

  Examples of the infrared absorbing pigment used as the photothermal conversion agent in the present invention include commercially available pigments and Color Index (CI) Handbook, “Latest Pigment Handbook” (edited by the Japan Pigment Technical Association, published in 1977), “Latest Pigment Application”. Examples thereof include pigments described in “Technology” (CMC Publishing, 1986) and “Printing Ink Technology” CMC Publishing, 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 , Quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like. 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” (Yokoshobo), “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, and preferably in the range of 0.05 μm to 1 μm, from the viewpoint of the stability of the dispersion in the recording layer coating liquid and the uniformity of the recording layer. More preferably, it is preferably in the range of 0.1 μm to 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).

  These (A) photothermal conversion agents are 0.01 to 30% by mass, preferably 0.1%, based on the total solid content constituting the recording layer, from the viewpoint of balance of sensitivity, uniformity of the recording layer, and durability. In the case of a dye, it is particularly preferably 0.1 to 5% by mass, and in the case of a pigment, it is particularly preferably 0.2 to 10% by mass.

[Water-insoluble and alkali-soluble resin]
In the recording layer according to the present invention, it is preferable to use a water-insoluble and alkali-soluble resin (hereinafter, appropriately referred to as an alkali-soluble resin) from the viewpoint of improving the film property.
Examples of the alkali-soluble resin that can be used in the positive recording layer include homopolymers containing an acidic group in the main chain and / or side chain in the polymer, copolymers thereof, or mixtures thereof.
Among them, those having the acidic groups listed in (1) to (6) mentioned in the description of the (c) acid group-containing monomer in the specific copolymer in the main chain and / or side chain of the polymer are alkaline. It is preferable in terms of solubility in a developing solution and expression of dissolution inhibiting ability.

  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.

Hereinafter, the alkali-soluble resin having an acidic group selected from the above (1) to (6) will be described.
(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-mixed) 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 an 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 these, low molecular compounds 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 are preferable. For example, the following general formula (i) to general formula Examples include compounds represented by formula (v).

In general formula (i) to general formula (v), 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 formulas (i) to (v), in the positive planographic printing plate precursor of the present invention, in particular, m-aminosulfonylphenyl methacrylate and N- (p-aminosulfonylphenyl) methacryl are used. Amide, 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.

  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.

  The total content of the alkali-soluble resin in the present invention is preferably from 30 to 98% by mass, and preferably from 40 to 95% by mass in the total solid content of the recording layer, from the viewpoints of sensitivity of the recording layer, image formability and durability. % Is more preferable.

[Other additives]
[(C) Development inhibitor]
The recording layer according to the present invention may contain (C) a development inhibitor for the purpose of enhancing its inhibition (dissolution inhibiting ability). In particular, when the (A) photothermal conversion agent (infrared absorbing agent) that does not have dissolution inhibiting ability is used, this development inhibitor can be an important component for maintaining the alkali resistance of the image area.
As the development inhibitor used in the present invention, it forms an interaction with the specific polymer compound or other alkali-soluble resin, and substantially reduces the solubility of the alkali-soluble resin in the developer in the unexposed area, In addition, the exposed portion is not particularly limited as long as the interaction is weakened and can be soluble in the developer, but quaternary ammonium salts, polyethylene glycol compounds and the like are particularly preferably used. Among the image colorants described below, there are compounds that function as a development inhibitor, and these are also preferred.

Although it does not specifically limit as a quaternary ammonium salt, A tetraalkyl ammonium salt, a trialkyl aryl ammonium salt, a dialkyl diaryl ammonium salt, an alkyl triaryl ammonium salt, a tetraaryl ammonium salt, a cyclic ammonium salt, and a bicyclic ammonium salt are mentioned. .
Specifically, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, tetraoctylammonium bromide, tetralaurylammonium bromide, tetraphenylammonium bromide, tetranaphthylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide , Tetrastearyl ammonium bromide, lauryl trimethyl ammonium bromide, stearyl trimethyl ammonium bromide, behenyl trimethyl ammonium bromide, lauryl triethyl ammonium bromide, phenyl trimethyl ammonium bromide, 3-trifluoromethylphenyl trimethyl ammonium bromide, benzyl trimethyl ammonium bromide De, dibenzyl dimethyl ammonium bromide, distearyl dimethyl ammonium bromide, tristearyl methyl ammonium bromide, benzyl triethyl ammonium bromide, hydroxyphenyl trimethyl ammonium bromide, N- methyl pyridinium bromide, and the like. In particular, quaternary ammonium salts described in Japanese Patent Application Nos. 2001-226297, 2001-370059, and 2001-398047 are preferable.

  The addition amount of the quaternary ammonium salt is preferably 0.1 to 25% by mass with respect to the total solid content of the single-layer recording layer, from the viewpoint of the development inhibiting effect and the film forming property of the alkali-soluble resin. More preferably, it is 0.5-15 mass%.

Moreover, it does not specifically limit as a polyethyleneglycol compound, The thing of the structure represented with the following general formula (I) is mentioned.
^{R 1 - {- O- (R} 3 -O-) m -R 2} n ··· general formula (I)
In the general formula (I), R ¹ represents a polyhydric alcohol residue or a polyhydric phenol residue, and R ² represents a hydrogen atom or an alkyl group having 1 to 25 carbon atoms which may have a substituent. Represents an alkenyl group, an alkynyl group, an alkylyl group, an aryl group or an aryloyl group. R ³ represents an alkylene residue which may have a substituent, m represents an average of 10 or more, and n represents an integer of 1 to 4.

  Examples of the polyethylene glycol compound represented by the general formula (I) include polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, Polyethylene glycol alkyl aryl ethers, polypropylene glycol alkyl aryl ethers, polyethylene glycol glycerol esters, polypropylene glycol glycerol esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyethylene glycol Lumpur ethylenediamines, polypropylene glycolated ethylenediamines, polyethylene glycolated diethylenetriamine, and polypropylene glycol diethylenetriamines.

  Specific examples thereof include polyethylene glycol 1000, polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 10000, polyethylene glycol 20000, polyethylene glycol 5000, polyethylene glycol 100000, polyethylene glycol 200000, polyethylene glycol 500000, polypropylene glycol 1500, polypropylene glycol. 3000, polypropylene glycol 4000, polyethylene glycol methyl ether, polyethylene glycol ethyl ether, polyethylene glycol phenyl ether, polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol diphenyl ether Polyethylene glycol lauryl ether, polyethylene glycol dilauryl ether, polyethylene glycol nonyl ether, polyethylene glycol cetyl ether, polyethylene glycol stearyl ether, polyethylene glycol distearyl ether, polyethylene glycol behenyl ether, polyethylene glycol dibehenyl ether, polypropylene glycol methyl ether, Polypropylene glycol ethyl ether, polypropylene glycol phenyl ether, polypropylene glycol dimethyl ether, polypropylene glycol diethyl ether, polypropylene glycol diphenyl ether, polypropylene glycol lauryl ether, polypropylene glycol dilauryl ether Polypropylene glycol nonyl ether, polyethylene glycol acetyl ester, polyethylene glycol diacetyl ester, polyethylene glycol benzoate ester, polyethylene glycol lauryl ester, polyethylene glycol dilauryl ester, polyethylene glycol nonyl acid ester, polyethylene glycol cetylate ester, polyethylene glycol stearoyl ester, polyethylene Glycol distearoyl ester, polyethylene glycol behenate ester, polyethylene glycol dibehenate ester, polypropylene glycol acetyl ester, polypropylene glycol diacetyl ester, polypropylene glycol benzoate ester, polypropylene glycol dibenzoate ester , Polypropylene glycol laurate, polypropylene glycol dilaurate, polypropylene glycol nonyl ester, polyethylene glycol glycerol ether, polypropylene glycol glycerol ether, polyethylene glycol sorbitol ether, polypropylene glycol sorbitol ether, polyethylene glycolated ethylenediamine, polypropylene glycolated ethylenediamine, Examples thereof include polyethylene glycolized diethylenetriamine, polypropylene glycolated diethylenetriamine, and polyethylene glycolated pentamethylenehexamine.

  The addition amount of the polyethylene glycol-based compound is preferably 1 to 25% by mass, and 3 to 15% by mass with respect to the total solid content of the single-layer recording layer, from the viewpoint of the development inhibiting effect and image forming property. It is more preferable.

In addition, when measures are taken to increase such inhibition (dissolution suppression ability), the sensitivity decreases. In this case, it is effective to add a lactone compound to the recording layer to suppress the sensitivity decrease. It is. This lactone compound reacts with the developer and the lactone compound when the developer penetrates into the recording layer in the exposed area, i.e., the area where the inhibition is released, and a new carboxylic acid compound is generated. It is considered that the sensitivity is improved by promoting the dissolution of the recording layer in the partial area. In the unexposed area, this lactone compound forms an interaction with a polar group in the alkali-soluble resin, for example, a hydroxyl group in the novolak resin, and is stable in the film together with a bulky structure having a ring. Therefore, even when an alkaline developer is contacted with the surface of the unexposed area, the rapid opening of the lactone ring during the development process is suppressed, so that the development resistance of the region is reduced. Absent. Since this interaction is more easily released by exposure or heating than the suppression effect by the development inhibitor, the ring-opening reaction of the lactone compound in the exposed area is performed quickly.
Such a lactone compound is not particularly limited, and examples thereof include compounds represented by the following general formula (LI) and general formula (L-II).

In general formula (LI) and general formula (L-II), X ¹ , X ² , X ³ and X ⁴ are divalent nonmetallic atoms or nonmetallic atomic groups constituting the ring, It can be the same or different. Moreover, these may each independently have a substituent. Furthermore, at least one of X ¹ , X ² and X ^{3 in} the general formula (LI) and at least one of X ¹ , X ² , X ³ and X ^{4 in} the general formula (L-II) is: The substituent is preferably an electron-withdrawing group or a substituent substituted with an electron-withdrawing group.

  A preferred nonmetallic atom or nonmetallic atomic group is an atom or atomic group selected from a methylene group, a sulfinyl group, a carbonyl group, a thiocarbonyl group, a sulfonyl group, a sulfur atom, an oxygen atom, and a selenium atom, and more preferably, It is an atomic group selected from a methylene group, a carbonyl group and a sulfonyl group.

  In this specification, the electron-withdrawing substituent refers to a group in which Hammett's substituent constant σp takes a positive value. For Hammett's substituent constants, see Journal of Medicinal Chemistry, 1973, Vol. 16, no. 11, 1207-1216 etc. can be referred to. Examples of electron-withdrawing groups in which Hammett's substituent constant σp takes a positive valence include halogen atoms [fluorine atoms (σp value: 0.06), chlorine atoms (σp value: 0.23), bromine atoms (σp value). : 0.23), iodine atom (σp value: 0.18)], trihaloalkyl group [tribromomethyl (σp value: 0.29), trichloromethyl (σp value: 0.33), trifluoromethyl (σp Value: 0.54)], cyano group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group [for example, methanesulfonyl (σp value: 0. 72)], aliphatic / aryl or heterocyclic acyl groups [for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)], alkynyl groups [for example, C≡CH (σp value: 0) .23)], Aliphatic Ali Or a heterocyclic oxycarbonyl group [for example, methoxycarbonyl (σp value: 0.45), phenoxycarbonyl (σp value: 0.44)], carbamoyl group (σp value: 0.36), sulfamoyl group (σp value: 0.57), sulfoxide groups, heterocyclic groups, oxo groups, phosphoryl groups and the like.

Preferred examples of the electron withdrawing group include an amide group, an azo group, a nitro group, a fluoroalkyl group having 1 to 5 carbon atoms, a nitrile group, an alkoxycarbonyl group having 1 to 5 carbon atoms, and an acyl group having 1 to 5 carbon atoms. , An alkylsulfonyl group having 1 to 9 carbon atoms, an arylsulfonyl group having 6 to 9 carbon atoms, an alkylsulfinyl group having 1 to 9 carbon atoms, an arylsulfinyl group having 6 to 9 carbon atoms, and an arylcarbonyl group having 6 to 9 carbon atoms , A thiocarbonyl group, a fluorine-containing alkyl group having 1 to 9 carbon atoms, a fluorine-containing aryl group having 6 to 9 carbon atoms, a fluorine-containing allyl group having 3 to 9 carbon atoms, an oxo group, and a group selected from a halogen element. More preferably, a nitro group, a fluoroalkyl group having 1 to 5 carbon atoms, a nitrile group, an alkoxycarbonyl group having 1 to 5 carbon atoms, an acyl group having 1 to 5 carbon atoms, a carbon number 6 9 arylsulfonyl group, an arylcarbonyl group having 6 to 9 carbon atoms, an oxo group, and a halogen element.
Specific examples of the compounds represented by general formula (LI) and general formula (L-II) are shown below, but the present invention is not limited to these compounds.

The addition amount of the compound represented by the general formula (LI) and the general formula (L-II) is based on the total solid content of the single-layer recording layer from the viewpoint of the effectiveness of the addition and the effect of image formation. 0.1-10 mass% is preferable, Furthermore, 0.2-6 mass% is more preferable.
Any one lactone compound may be used in the present invention, or two or more lactone compounds may be used in combination. In addition, when two or more compounds of the general formula (LI) or two or more compounds of the general formula (L-II) are used, they should be used in any ratio as long as the total addition amount is within the above range. Can do.

  In addition, substances that are thermally decomposable, such as onium salts, o-quinonediazide compounds, aromatic sulfone compounds, aromatic sulfonic acid ester compounds, and that substantially reduce the solubility of alkali-soluble resins when not decomposed. Is preferably used from the viewpoint of improving the inhibition of the image portion in the developer.

  Examples of the onium salt used in the present invention include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, arsonium salts, and the like. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Balet al, Polymer, 21, 423 (1980), diazonium salts described in JP-A-5-158230, U.S. Pat. Nos. 4,069,055, 4,069,056, and JP-A-3-140140. Ammonium salts described in the specification, D.I. C. Necker et al, Macromolecules, 17, 2468 (1984), C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056,

  J. et al. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, US Pat. Nos. 5,041,358, 4,491,628, JP-A-2-150848 and JP-A-2-296514. Iodonium salts, J.M. V. Crivello et al, Polymer J. et al. 17, 73 (1985), J. Am. V. Crivello et al. J. et al. Org. Chem. 43, 3055 (1978); R. Watt et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 22, 1789 (1984), J. Am. V. Crivello et al, Polymer Bull. , 14, 279 (1985),

  J. et al. V. Crivello et al, Macromolecules, 14 (5), 1141 (1981), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. 17, 2877 (1979), European Patents 370,693, 233,567, 297,443, 297,442, U.S. Pat. Nos. 4,933,377, 3,902,114 No. 4,491,628, No. 4,760,013, No. 4,734,444, No. 2,833,827, German Patent No. 2,904,626, No. 3,604 The sulfonium salt described in No. 580 and No. 3,604,581,

J. et al. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988).
Of these onium salts, a diazonium salt is particularly preferable. Particularly suitable diazonium salts include those described in JP-A-5-158230.

  The counter ion of the onium salt includes tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfone Examples include acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid. Of these, particularly preferred are alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid.

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 assists the solubility of the upper layer by the effects of both losing the inhibition as a development inhibitor due to thermal decomposition and changing o-quinonediazide itself into an alkali-soluble substance.
Examples of such o-quinonediazide compounds include J. Org. The compounds described in pages 339 to 352 of “Light-sensitive systems” by John Coley (John Wiley & Sons. Inc.) can be used. The sulfonic acid esters or sulfonic acid amides 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-5 described in US Pat. Nos. 3,046,120 and 3,188,210. Esters of sulfonic acid chloride and phenol-formaldehyde resin are also preferably used.

  Further, an ester of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and 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, 49-17474, U.S. Pat. Nos. 2,797,213, 3,454,400, 3,544,323, 3,573,917, 3,674,495, 3,785,825, British Patents 1,227,602, 1,251,345, 1,267, No. 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 0.1 to 8% by mass, more preferably 0.2 to 5% by mass, based on the total solid content of the single-layer recording layer. These compounds can be used alone, but may be used as a mixture of several kinds.
Moreover, you may contain the alkali-soluble resin by which at least one part of Unexamined-Japanese-Patent No. 11-288089 was esterified.

Further, for the purpose of enhancing the inhibition of the surface of the recording layer and the scratch resistance of the surface, the perfluoroalkyl having 3 to 20 carbon atoms in the molecule as described in JP-A-2000-187318 is also disclosed. It is preferable to use a polymer having a (meth) acrylate monomer having 2 or 3 groups as a polymerization component.
The addition amount is preferably 0.5 to 15% by mass, more preferably 1 to 10% by mass, based on the total solid content of the single-layer recording layer.

[Other additives]
In forming the recording layer according to the present invention, in addition to the above essential components and preferred components, various additives can be added as necessary as long as the effects of the present invention are not impaired.
<Development accelerator>
For the purpose of improving sensitivity, acid anhydrides, phenols, and organic acids may be added to the recording layer according to the present invention.
As the acid anhydrides, cyclic acid anhydrides are preferable. Specific examples of the cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride described in US Pat. No. 4,115,128. Acid, 3,6-endooxy-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Examples of the acyclic acid anhydride include acetic anhydride.

  Examples of phenols include bisphenol A, 2,2′-bishydroxysulfone, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4- Examples include hydroxybenzophenone, 4,4 ′, 4 ″ -trihydroxytriphenylmethane, 4,4 ′, 3 ″, 4 ″ -tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane. .

Examples of organic acids include sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755. Specifically, 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-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like.
The proportion of the acid anhydride, phenols and organic acids in the total solid content of the single-layer recording layer is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, and particularly preferably 0. .1 to 10% by mass.

<Surfactant>
The recording layer according to the present invention is described in Japanese Patent Application Laid-Open Nos. 62-251740 and 3-208514 in order to improve the coating properties and to expand the processing stability against 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-62-170950, JP-A-11-288093, and Japanese Patent Application No. 2001-247351 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 amphoteric activators 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 Seiyaku Co., Ltd.).

As the siloxane compound, a block copolymer of dimethylsiloxane and polyalkylene oxide is preferable. 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 amphoteric surfactant in the total solid content of the recording layer is preferably 0.01 to 15% by mass, more preferably 0.1 to 5.0% by mass, and still more preferably 0.8. 5 to 2.0% by mass.

<Bake-out agent / colorant>
To the recording layer according to 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, No. 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 compounds and triazine 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) Co., Ltd.), Victoria Pure Blue, Crystal Violet Lactone, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI52015), etc. it can. The dyes described in JP-A-62-293247 are particularly preferred.
These dyes can be added in a proportion of 0.01 to 10% by mass, preferably 0.1 to 3% by mass, based on the total solid content of the recording layer.

<Plasticizer>
A plasticizer may be added to the recording layer according to the present invention in order to impart flexibility and the like 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.
These plasticizers can be added in a proportion of 0.5 to 10% by mass, preferably 1.0 to 5% by mass, based on the total solid content of the recording layer.

<WAX agent>
In the recording layer according to the present invention, for the purpose of imparting scratch resistance, a compound that lowers the static friction coefficient of the surface can also be added. Specifically, US Pat. No. 6,117,913 or Japanese Patent Application Nos. 2001-261627, 2002-032904, and 2002-165854 previously proposed by the applicant of the present application. And compounds having esters of long-chain alkyl carboxylic acids, as described in.
As the addition amount, the proportion of the total solid content in the recording layer is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass.

[Preparation of lithographic printing plate precursor]
A lithographic printing plate precursor can be produced by dissolving the components for a coating solution of a desired layer, such as a recording layer coating solution and a protective layer coating solution according to the present invention, in a solvent and coating the solution on a suitable support. .
The recording layer may have a single layer structure or a multilayer structure.
When the recording layer of the lithographic printing plate precursor according to the present invention has a multilayer structure composed of a plurality of layers having different constituent components, for example, a lower layer containing an alkali-soluble resin, an alkali-soluble resin, and the alkali-soluble resin And an upper layer that can form an image by irradiation with infrared rays, and contains a specific infrared absorber in at least one of the upper layer and the lower layer Can be taken. In this case, the specific copolymer and infrared absorber in the present invention are contained in the upper layer. The lower layer may be a layer containing an alkali-soluble resin as a main component, or may be a layer that further includes an infrared absorber or a dissolution inhibitor and functions as a positive recording layer.

The case where the recording layer according to the present invention has a multilayer structure will be described below.
-Lower layer component-
The lower layer according to the present invention is characterized by containing an alkali-soluble resin. As the alkali-soluble resin used here, the general alkali-soluble resin described above can be used, but in order to clarify the boundary between the upper layer and the lower layer, the alkali-soluble resin used in the lower layer is the alkali used in the upper layer. It is preferable that the main component is different from the soluble resin. Examples of the alkali-soluble resin suitably used for the lower layer include a copolymer of N- (p-aminosulfonylphenyl) (meth) acrylamide, (meth) acrylic acid alkyl ester and acrylonitrile, 4-maleimidobenzenesulfonamide and styrene. Copolymers, alkali-soluble resins having highly polar units such as copolymers of (meth) acrylic acid, N-phenylmaleimide, and (meth) acrylamide, or those resins in which the specific substituent is introduced However, the present invention is not limited to these.
The content of the total alkali-soluble resin in the lower layer of the multilayer recording layer is preferably 50 to 100% by mass in the total solid content of the lower recording layer from the viewpoint of printing durability and multilayer formation. 75 to 99% by mass is more preferable, and 85 to 95% by mass is particularly preferable.
The lower layer may or may not contain the specific copolymer.

  In addition, other additives may be used for the lower layer component according to the present invention, if necessary. Examples of other additives include development accelerators, surfactants, printout / coloring agents, plasticizers, and WAX agents. Details of these components are the same as those described above.

-Upper layer component-
The upper layer according to the present invention contains an alkali-soluble resin and a compound that interacts with the alkali-soluble resin and decreases the solubility in an aqueous alkali solution (generally, an infrared-absorbing dye such as a cyanine dye having the function) An image can be formed by irradiation with infrared rays. The upper layer component is the same as that described above as the recording layer. In the present invention, the recording layer containing the specific copolymer and the infrared absorber is used as the upper layer.

Solvents used for coating the recording layer 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, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, toluene, water, etc. However, the present invention is not limited to this. 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.

  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 coating solution according to the present invention, a surfactant for improving the coating property, for example, a fluorosurfactant described in JP-A-62-170950 may be added. it can. A preferable addition amount is 0.01 to 1% by mass in terms of solid content in the recording layer, and more preferably 0.05 to 0.5% by mass.

In the multilayer recording layer, it is preferable to form the lower layer and the upper layer by separating the two layers in principle.
As a method for forming the two layers separately, for example, a method using a difference in solvent solubility between a component contained in the lower layer and a component contained in the upper layer, or after applying the upper layer, a solvent is rapidly used. For example, a method of drying and removing.
Hereinafter, although these methods are explained in full detail, the method of isolate | separating and apply | coating two layers is not limited to these.

  As a method of utilizing the difference in solvent solubility between the component contained in the lower layer and the component contained in the upper layer, a solvent system in which any of the components contained in the lower layer is insoluble is used when the upper layer coating solution is applied. Is. Thereby, even if it carries out 2 layer application | coating, it becomes possible to isolate | separate each layer clearly and to make a coating film. For example, as the lower layer component, a component insoluble in a solvent such as methyl ethyl ketone or 1-methoxy-2-propanol that dissolves the alkali-soluble resin that is the upper layer component is selected, and the lower layer is applied using a solvent system that dissolves the lower layer component. -It is possible to form two layers by drying and then dissolving the upper layer component mainly composed of alkali-soluble resin with methyl ethyl ketone, 1-methoxy-2-propanol, etc., and applying and drying.

  Next, after applying the second layer (upper layer), as a method of drying the solvent very quickly, a method of blowing high-pressure air from a slit nozzle installed substantially perpendicular to the running direction of the web, heating with steam, etc. The method of giving thermal energy as conduction heat from the lower surface of the web from the roll (heating roll) supplied inside the medium, or a combination of these methods can be mentioned.

  Moreover, in order to provide a new function, the upper layer and the lower layer may be partially miscible in a range where the effects of the present invention are sufficiently exhibited. Such a method can be achieved by adjusting the degree of any of the above methods using the difference in solvent solubility and the method of drying the solvent very quickly after coating the second layer.

Moreover, the recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the application, but as the coating amount decreases, the apparent sensitivity increases, but the film properties of the recording layer decrease. .
In the single-layer recording layer, the coating amount of the recording layer component after drying is generally preferably from 0.5 to 5.0 g / m ² from the viewpoint of sensitivity, printing durability, and the like, and preferably from 0.7 to 4 More preferably, it is in the range of 0.0 g / m ² , and still more preferably in the range of 0.8 to 3.0 g / m ² .
In the multi-layer recording layer, the coating amount of the lower layer component after drying is preferably in the range of 0.5 to 4.0 g / m ² , more preferably 0.6, from the viewpoint of sensitivity and printing durability. It is in the range of ˜2.5 g / m ² . Further, the coating amount after drying of the upper layer component is preferably in the range of 0.05 to 1.0 g / m ² , and more preferably 0.08 to 0.08 from the viewpoints of sensitivity, development latitude, scratch resistance, and the like. The range is 0.7 g / m ² .
The coating amount after drying combining the lower layer and the upper layer is preferably in the range of 0.6 to 4.0 g / m ² , more preferably from the viewpoint of sensitivity, image reproducibility, printing durability, and the like. in the range of 0.7 to 2.5 g / m ^2.

[Support]
The support used for the lithographic printing plate precursor according to the present invention is not particularly limited as long as it is a dimensionally stable plate having necessary strength and durability. For example, paper, plastic (for example, Paper laminated with polyethylene, polypropylene, polystyrene, etc., metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, Cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper laminated with a metal as described above, or vapor-deposited paper, or a plastic film.

  Among them, in the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. 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 foreign 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 present invention is not specified, and an aluminum plate made of a publicly known material 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.

Such an aluminum plate may be subjected to a surface treatment such as a roughening treatment or an anodizing treatment if necessary. Hereinafter, such a surface treatment will be briefly described.
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 aluminum plate roughened as described above is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodizing 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 part of the lithographic printing plate is easily damaged, and the ink adheres to the damaged part during printing. So-called “scratch stains” easily occur.
After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary.

  The hydrophilization treatment used in the present invention is disclosed in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There are alkali metal silicate (such as aqueous sodium silicate) methods. In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, it is disclosed in potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and US Pat. Nos. 3,276,868, 4,153,461, and 4,689,272. A method of treating with polyvinylphosphonic acid is used.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the support and the recording layer, if necessary.
Various organic compounds are used as the undercoat layer component. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, phenylphosphonic acid which may have a substituent, Organic phosphonic acids such as naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid, optionally substituted phenylphosphoric acid, naphthylphosphonic acid, alkylphosphoric acid and glycerophosphoric acid Organic phosphoric acid, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, organic phosphinic acids such as alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and hydrochloride of triethanolamine Hydroxy groups such as Selected from hydrochloride of the amine to be, but may be used by mixing two or more.

  The undercoat layer preferably contains a compound having an onium group. The compounds having an onium group are described in detail in JP-A Nos. 2000-10292 and 2000-108538. In addition, a compound selected from the group of polymer compounds having a structural unit represented by poly (p-vinylbenzoic acid) in the molecule can also be used. Specific examples of these polymer compounds include a copolymer of p-vinylbenzoic acid and vinylbenzyltriethylammonium salt, a copolymer of p-vinylbenzoic acid and vinylbenzyltrimethylammonium chloride, and the like. .

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 in which the above organic compound is dissolved in the above organic solvent or a mixed solvent thereof to adsorb the above compound, followed by washing with water or the like and drying 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 a basic substance such as ammonia, triethylamine or potassium hydroxide, or an acidic substance such as hydrochloric acid or phosphoric acid. A yellow dye can also be added to improve the tone reproducibility of the image recording material.
The coverage of the organic undercoat layer, from the viewpoint of printing durability, 2 to 200 mg / m ² are suitable, and preferably from 5 to 100 mg / m ^2.
The lithographic printing plate precursor produced as described above is imagewise exposed and then developed.

(Back coat layer)
A back coat layer is provided on the back surface of the support of the lithographic printing plate precursor according to the invention, if necessary. Such a back coat layer comprises a metal oxide obtained by hydrolysis and polycondensation of an organic polymer compound described in JP-A-5-45885 and an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Among these coating layers, silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , and Si (OC ₄ H ₉ ) ₄ are available at a low price. The coating layer of the metal oxide obtained therefrom is particularly preferable because of its excellent developer resistance.

〔exposure〕
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.

[Development processing]
As the developer and replenisher for the lithographic printing plate precursor according to the invention, 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. In addition, 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 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 PS plates have been widely used in the stencil 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 conveying the PS plate, each processing liquid tank and a spray device, and the exposed PS plate is pumped up while being transported horizontally. Each processing solution is sprayed from a spray nozzle to develop and post-process. In addition, recently, a PS plate is immersed and transported in a processing solution tank filled with a processing solution by a guide roll in the solution, and a small amount of washing water after development is supplied to the plate surface for washing. A method is also known in which the waste water is reused as dilution water for the developer stock solution.

  In such automatic processing, each processing solution can be processed while being replenished with each 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 lithographic printing plate precursor according to the invention, image portions unnecessary for the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming (for example, film edge marks of the original film, etc.) ), Unnecessary image portions are erased. Such erasing is preferably performed, for example, by applying an erasing solution as described in Japanese Patent Publication No. 2-13293 to an unnecessary image portion, leaving it for a predetermined time, and then washing with water. As described in JP-A-59-174842, a method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber can also be used.

The lithographic printing plate obtained from the lithographic printing plate precursor of the present invention as described above can be subjected to a printing process after applying a desensitizing gum if desired, but lithographic printing with a higher printing durability. If you want to make a plate, you will be burned. 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 lithographic 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 Hereinafter, although this invention is demonstrated according to an Example, the scope of 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. 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 perform an etching treatment, and the aluminum plate was 6 g / m. 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 is electrochemically roughened using a carbon electrode as the 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) 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 at 0.10 g / m ² , 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 dissolved 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 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 1-7, Comparative Examples 1-2]
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 performed at 130 ° C. for 90 seconds in a drying oven, and positive lithographic printing plate precursors of Examples 1 to 7 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) 0.098 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
・ 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. This 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 added to 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>
-Copolymer of ethyl methacrylate and 2-methacryloyloxyethyl succinic acid (molar ratio 75:25, weight average molecular weight 70,000) 0.050 g
Phenol cresol-formaldehyde novolak (phenol: m-cresol: p-cresol = 40: 20: 40, weight average molecular weight: 8800) 0.500 g
-Specific sulfonium salt (compound described in Table 1 or comparative compound A) 0.03 g
・ 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

[Evaluation of lithographic printing plate precursor]
Evaluation of the lithographic printing plate precursor was performed for each item of ink inking property and scratch resistance. Details of the evaluation method are as follows.

1. Ink fillability A lithographic printing plate precursor was imagewise exposed using a TrendSetter 3244F manufactured by CREO at a setter exposure of 8.0 W and 150 rpm, and a developer DT-2 (1: 8 by Fuji Photo Film Co., Ltd.) Diluted) and Fuji Photo Film Co., Ltd. finisher FG-1 (diluted 1: 1), and a Fuji Photo Film Co., Ltd. PS processor LP940H was used. Developed in time 25s. The electric conductivity of the developer at this time was 43 mS / cm. After the development process, the image was applied to a printing machine, and the number of printed sheets required to obtain a printed matter having no problem of ink depositing on the image area was relatively evaluated. Then, the time until a problem-free printed matter is obtained by the planographic printing plate precursor of Example 1 is expressed as a relative value with reference to (100). As this relative value is larger, it is preferable because it is more thick.
2. Scratch resistance evaluation The obtained lithographic printing plate precursor was scratched by applying a load to a sapphire needle (tip diameter 1.0 mm) with a scratch tester manufactured by HEIDON. Thereafter, the image was exposed imagewise at a beam intensity of 9.0 W and a drum rotation speed of 125 rpm with a Trend setter 3244F manufactured by Creo. Fuji Photo Film Co., Ltd. was supplied with Developer DT-2 (diluted 1: 8) and Fuji Photo Film Co., Ltd. Finisher FG-1 (diluted 1: 1). Using a PS processor LP940H manufactured by Co., Ltd., the liquid temperature was maintained at 30 ° C., and development was performed for 15 seconds. The electric conductivity of the developer at this time was 45 mS / cm. The developed lithographic printing plate was visually observed, and the maximum load (g) without scratches was taken as the value of scratch resistance. The larger the value, the better the scratch resistance.
About each lithographic printing plate precursor of Examples 1 to 7 and Comparative Example 1, the ink deposition property and scratch resistance were evaluated by the methods described above. The results are shown in Table 1.

  As is apparent from Table 1, the lithographic printing plate precursor according to the present invention was excellent in inking property and scratch resistance. On the other hand, the planographic printing plate precursor of Comparative Example 1 using an alkylammonium salt instead of the specific sulfonium salt of the present invention was inferior to the Examples in terms of both flaking property and scratch resistance.

(Examples 8 to 14, Comparative Example 2)
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 8 to 14 and Comparative Example 2 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
-The counter anion of ethyl violet is changed to 6-hydroxynaphthalenesulfonic acid 0.100 g
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.030 g
・ Fluorosurfactant 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 0.020 g
Copolymer (molar ratio 70:30, weight average molecular weight 88,000)
Phenol cresol-formaldehyde novolak (phenol: m-cresol: p-cresol = 30: 40: 30,
(Weight average molecular weight: 7700) 0.260 g
Specific sulfonium salt (compound described in Table 2 or comparative compound A) 0.03 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

  The obtained planographic printing plate precursors of Examples 8 to 14 and Comparative Example 2 were evaluated in the same manner as in Example 1. The results are shown in Table 2.

  Table 2 shows that even if the composition of the recording layer changes, the planographic printing plate precursor of the present invention is excellent in fleshing property and scratch resistance.

(Examples 15 to 21, Comparative Example 3)
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 15 to 21 and Comparative Examples 5 to 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 0.0380 g
(Molar ratio 65:35, weight average molecular weight 78,000)
-Cresol-formaldehyde novolak (m-cresol: p-cresol = 80: 20, weight average molecular weight: 4100)
0.400g
Specific sulfonium salt (compound described in Table 3 or comparative compound A) 0.0310 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

  The obtained planographic printing plate precursors of Examples 15 to 21 and Comparative Example 3 were evaluated in the same manner as in Example 1. The results are shown in Table 3.

  From Table 3, it can be seen that even if the composition of the recording layer changes, the planographic printing plate precursor of the present invention is excellent in fleshing property and scratch resistance.

(Examples 22 to 28, Comparative Example 4)
The following image-forming layer coating solution was applied to the obtained support D and dried at 120 ° C. for 90 seconds to form image-forming layers. The planographic printing plate precursors of Examples 22 to 28 and Comparative Examples 7 to 8 Got. The coating amount after drying was 1.60 g / m ² .

<Image forming layer coating solution>
Phenol cresol-formaldehyde novolak (phenol: m-cresol: p-cresol = 40: 20: 40
Weight average molecular weight: 6500) 1.5 g
Specific sulfonium salt (compound described in Table 4 or comparative compound A) 0.025 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

  The lithographic printing plate precursors obtained in Examples 22 to 28 and Comparative Example 4 were evaluated in the same manner as in Example 1. The results are shown in Table 4.

  From Table 4, it can be seen that the planographic printing plate precursor of the present invention is excellent in the inking property and scratch resistance even when the recording layer has a single layer structure.

Claims (1)

A recording layer made of a positive photosensitive composition containing (A) a photothermal conversion agent and (B) a sulfonium salt represented by the following general formula (1) is provided on a support. A lithographic printing plate precursor.

In the formula, each of R ¹ , R ² , and R ³ independently represents an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group, and at least one of R ^{1 to} R ³ is an alkyl group or a cycloalkyl group. It is.
X ⁻ represents a strong acid residue.