JP2007225701A - Method for making lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for making a lithographic printing plate in which a lithographic printing original plate for scanning exposure having high sensitivity to an oscillation wavelength of an inexpensive short-wavelength semiconductor laser and excellent also in storage stability and suitability to safelight is developed with an aqueous developer of pH 2.0-10.0. <P>SOLUTION: In the method for making a lithographic printing plate, the lithographic printing original plate having a photosensitive layer containing (A) a sensitizing dye having a specific structure, (B) an initiator compound, (C) a polymerizable compound and (D) a hydrophobic binder polymer having an acid number of ≤0.3 meq/g and a protective layer in this order on a hydrophilic support is exposed with a laser having a wavelength of 350-450 nm, and then the protective layer and an unexposed portion of the photosensitive layer are removed by rubbing the plate surface with a rubbing member in the presence of a developer of pH 2-10 by using an automatic processing machine equipped with the rubbing member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for preparing a lithographic printing plate.

In general, a lithographic printing plate has a surface composed of an oleophilic image portion and a hydrophilic non-image portion. In lithographic printing, dampening water and oil-based ink are alternately applied to the plate surface, and the hydrophilic non-image area is dampened with a dampening water receiving area (ink non-receiving area) by utilizing the property that water and oil repel each other. ), After the ink is received only in the oleophilic image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive layer (image recording layer) is provided on a hydrophilic support has been widely used. Usually, after exposing the lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer to be an image portion is left, and the other unnecessary image recording layer is removed with an alkaline developer or an organic solvent. The lithographic printing plate is obtained by carrying out plate making by a method in which the surface of the hydrophilic support is exposed by dissolving and removing to form a non-image portion.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing unnecessary image recording layers with a developer or the like is necessary after exposure, but simplifies such additional wet processing. This is one of the issues. As one of simplification, it is desired that development can be performed with an aqueous solution close to neutrality or simple water.

  On the other hand, in recent years, digitization technology that electronically processes, stores, and outputs image information using a computer has become widespread, and various new image output methods corresponding to such digitization technology have been put into practical use. It has come to be. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate technology for manufacturing is attracting attention. Accordingly, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.

  From the background as described above, it is now more strongly desired than ever to adapt both the simplification of the plate making operation and the digitization.

  On the other hand, for example, in Patent Document 1, in an image forming layer of a lithographic printing plate precursor having an image forming layer containing a hydrophobic precursor, a hydrophilic resin, and a photothermal conversion agent on a hydrophilic support. In addition to on-press development, it can be used for printing after being exposed to a liquid development treatment using water or a suitable aqueous solution as a developer, by containing a compound having an ethylene oxide chain. ing.

Patent Document 2 contains (i) a hydrophilic support, and (ii) a radical polymerizable ethylenically unsaturated monomer, a radical polymerization initiator and an infrared absorbing dye, and is cured by infrared laser exposure. Moreover, a lithographic printing plate precursor comprising an oleophilic heat-sensitive layer containing 60% by mass or more of water and developable with an aqueous developer having a pH of 2.0 to 10.0 is prepared and exposed imagewise with an infrared laser. A method for processing a lithographic printing plate precursor comprising removing an uncured region of a heat-sensitive layer with an aqueous developer is described.
However, in order to maintain developability with respect to an aqueous developer having a pH of 2.0 to 10.0, the photosensitive layer needs to be hydrophilic or highly water-permeable. However, such a photosensitive layer has insufficient water resistance and film strength at a portion cured by exposure. To overcome this problem, a highly sensitive reaction system with high curing efficiency improves the water resistance discrimination between the unexposed and exposed areas, and does not cause fog when handled under safelight. Is required and its development is desired.
JP 2002-365789 A US Patent Application Publication No. 2004/0013968

  The present invention meets the above needs. That is, an object of the present invention is to provide a method for preparing a lithographic printing plate in which a lithographic printing plate precursor having high sensitivity and excellent safelight suitability is developed with an aqueous developer having a pH of 2.0 to 10.0.

  The present inventor has found that the above problem can be solved by using a sensitizing dye having a specific structure in the photosensitive layer. That is, the present invention is as follows.

  (1) On a hydrophilic support, (A) a sensitizing dye represented by the following general formula (I), (B) an initiator compound, (C) a polymerizable compound, and (D) an acid value of 0. After exposing a lithographic printing plate precursor having a photosensitive layer containing a hydrophobic binder polymer of 3 meq / g or less and a protective layer in this order with a laser having a wavelength of 350 to 450 nm, an automatic processor equipped with a rubbing member A method for producing a lithographic printing plate, comprising removing a protective layer and a photosensitive layer in an unexposed area by rubbing the plate surface with a rubbing member in the presence of a developer having a pH of 2 to 10.

(In the general formula (I), X ₁ and X ₂ each independently represents an oxygen atom, a sulfur atom, —CR ₁₁ R ₁₂ — or —NR ₁₃ —, wherein at least one of them represents an oxygen atom, a sulfur atom or -NR ₁₃ -. a it .Y represents an oxygen atom, a sulfur atom or = NR ₁₄ .R _{1 ~R 14} each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, or R ₁ to R ₁₄ is They may be bonded to each other to form an aliphatic or aromatic ring.)
(2) (D) A hydrophobic binder polymer having an acid value of 0.3 meq / g or less is selected from a (meth) acrylic copolymer having a crosslinkable group in the side chain and a polyurethane resin having a crosslinkable group in the side chain. The method of preparing a lithographic printing plate as described in (1) above, wherein the lithographic printing plate is at least one kind.
(3) The method for preparing a lithographic printing plate as described in (1) or (2) above, wherein the initiator compound (B) is a hexaarylbiimidazole compound.
(4) A lithographic printing plate produced by the method for producing a lithographic printing plate as described in any one of (1) to (3) above.

  According to the present invention, a lithographic printing plate can be obtained by developing a lithographic printing plate precursor having high sensitivity and excellent safelight suitability with an aqueous developer having a pH of 2.0 to 10.0 after laser exposure. .

[Lithographic printing plate precursor]
First, the lithographic printing plate precursor used in the lithographic printing plate preparation method of the present invention will be described. The lithographic printing plate precursor has a photosensitive layer and a protective layer on a hydrophilic support.

<Photosensitive layer>
The photosensitive layer of the lithographic printing plate precursor according to the invention comprises (A) a sensitizing dye represented by the general formula (I), (B) an initiator compound, (C) a polymerizable compound, and (D) an acid value of 0.1. Contains a hydrophobic binder polymer of 3 meq / g or less. Here, (A) the sensitizing dye represented by the general formula (I) and (B) the initiator compound constitute a photoinitiating system in the photosensitive layer. The photosensitive layer of the present invention can further contain other components as required. Hereinafter, the components of the photosensitive layer will be described in detail.
(A) Sensitizing dye

  One of the characteristics of the sensitizing dye represented by the general formula (I) (hereinafter also referred to as a sensitizing dye having a specific structure) used in the photoinitiating system of the present invention is particularly in the 350 nm to 450 nm region. It has excellent absorption characteristics. Furthermore, the sensitizing dye having a specific structure efficiently causes decomposition of various (B) initiator compounds and exhibits very high photosensitivity. In general, the sensitization mechanism of a photoinitiating system composed of a sensitizing dye / initiator compound is (a) reductive decomposition of an initiator compound based on an electron transfer reaction from an electronically excited state of the sensitizing dye to the initiator compound, ( b) Oxidative decomposition of initiator compound based on electron transfer from initiator compound to electronically excited state of sensitizing dye, (c) Initiation based on energy transfer from electronically excited state of sensitizing dye to initiator compound Although the route of decomposition of the agent compound from the electronically excited state is known, it is estimated that the sensitizing dye of the present invention can cause any of these types of sensitization reactions with excellent efficiency.

  The present inventor has found that it is very important that the sensitizing dye has a structure represented by the general formula (I) in order to obtain high sensitivity and high storage stability. Although its mechanism of action is not sufficiently clear, the high sensitivity of the sensitizing dye of the present invention shows a high-intensity emission (fluorescence and / or phosphorescence) spectrum. Since the sensitizing dye of the present invention has a relatively long lifetime in the excited state, it is considered that the sensitizing dye effectively acts to increase the efficiency of the reaction with the initiator compound. In addition, there is a possibility that the structure represented by the general formula (I) contributes to the efficiency of the initial stage of the sensitization reaction (electron transfer, etc.) and the efficiency of the subsequent reaction leading to the decomposition of the initiator compound. is there. The polarity effect on the dye structure is related to the crystal precipitation in the photosensitive layer composition, and it is presumed that when a structure with a smaller polarity is taken, crystallization is suppressed and storage stability is increased.

  The sensitizing dye used in the present invention has a structure represented by the following general formula (I).

(In the general formula (I), X ₁ and X ₂ each independently represents an oxygen atom, a sulfur atom, —CR ₁₁ R ₁₂ — or —NR ₁₃ —, wherein at least one of them represents an oxygen atom, a sulfur atom or -NR ₁₃ -. a it .Y represents an oxygen atom, a sulfur atom or = NR ₁₄ .R _{1 ~R 14} each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, or R ₁ to R ₁₄ is They may be bonded to each other to form an aliphatic or aromatic ring.)

  Furthermore, it is preferable that the pigment | dye represented by general formula (I) is a structure represented by the following general formula (II).

(In the general formula (II), X ₂ represents an oxygen atom, a sulfur atom, —CR ₅ R ₆ — or —NR ₇ —. R ₅ , R ₆ , R ₇ and R _{17 to} R ₂₆ are each independently hydrogen. Represents an atom or a monovalent non-metallic atomic group, or R ₅ , R ₆ , R ₇ and R _{17 to} R ₂₆ may be bonded to each other to form an aliphatic or aromatic ring; .)

In the sensitizing dye represented by the general formula (II), when X ₂ is —CR ₅ R _6- (dialkylcarbon), the sensitizing dye is suppressed in crystallinity, and the storage stability of the photosensitive layer composition is improved. It is particularly preferable because it is excellent. Such a sensitizing dye is represented by the following general formula (III), for example.

(In the general formula (III), Alk represents a branched alkyl group having 1 to 10 carbon atoms. R _{17 to} R ₂₆ are the same as those defined in the general formula (II).)

The general formulas (I) to (III) will be described in more detail.
In the formula, each of R ₁ and R ₂ preferably represents a hydrogen atom or a substituted or unsubstituted alkyl group.
R _{3 to} R ₁₀ and R _{19 to} R ₂₆ are preferably a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a halogen atom, a cyano group, a substituted or unsubstituted alkoxycarbonyl group, or a substituted group. Alternatively, it represents an unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

Next, preferred examples of R _{1 to} R ₁₄ and R _{19 to} R ₂₆ will be specifically described. Examples of preferable alkyl groups include linear, branched, and cyclic alkyl groups having 1 to 20 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, Butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, s-butyl, Examples thereof include t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group, cyclopentyl group and 2-norbornyl group. Of these, linear alkyl groups having 1 to 12 carbon atoms, branched alkyl groups having 3 to 12 carbon atoms, and cyclic alkyl groups having 5 to 10 carbon atoms are more preferable.

As the substituent of the substituted alkyl group, a group of a monovalent nonmetallic atomic group is used. Preferred examples include halogen atoms (—F, —Br, —Cl, —I), hydroxyl groups, alkoxy groups, aryloxy groups. Group, mercapto group, alkylthio group, arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N-diarylcarbamoyloxy group, N -Alkyl-N-arylcarbamoyloxy group, alkylsulfoxy group, aryl Sulfoxy group, acyloxy group, acylthio group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-aryl Ureido group, N ′, N′-diarylureido group, N′-alkyl-N′-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N ′ -Alkyl-N-arylureido group, N ', N'-dialkyl-N-alkylureido group, N', N'-dialkyl-N-arylureido group, N'-aryl-N-alkylureido group, N ' -Aryl-N-arylureido group, N ', N'-diaryl-N-alkylureido group, N', N'-diaryl-N-arylureido group, N '-Alkyl-N'-aryl-N-alkylureido group, N'-alkyl-N'-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonyl Amino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group , Aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group Aryls Rufinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (—SO ₃ H) and its conjugate base group (hereinafter referred to as sulfonate group), alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfina Moyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfato group Famoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, phosphono group (—PO ₃ H ₂₎ and its conjugated base group (hereinafter referred to as phosphonato group), Jiarukiruho Honomoto _{(-PO 3 (alkyl) 2)} , diaryl phosphono group _{(-PO 3 (aryl) 2)} , alkyl aryl phosphono group _{(-PO 3 (alkyl) (aryl} )), monoalkyl phosphono group (- PO ₃ H (alkyl)) and its conjugate base group (hereinafter referred to as alkylphosphonate group), monoarylphosphono group (—PO ₃ H (aryl)) and its conjugate base group (hereinafter referred to as arylphosphonato group) ), Phosphonooxy group (—OPO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonatooxy group), dialkylphosphonooxy group (—OPO ₃ (alkyl) ₂ ), diarylphosphonooxy group (—OPO _3). (aryl) _2), alkylaryl phosphono group _{(-OPO 3 (alkyl) (aryl} )), monoalkyl phosphono group -OPO ₃ H (alkyl)) and its conjugated base group (hereinafter referred to as alkylphosphonato group), monoarylphosphono group (-OPO ₃ H (aryl)) and its conjugated base group (hereinafter, Ariruhosuho A cyano group, a nitro group, an aryl group, a heteroaryl group, an alkenyl group, an alkynyl group, and a silyl group.
Specific examples of the alkyl group in these substituents include the aforementioned alkyl groups, which may further have a substituent.

  Preferable examples of the alkoxy group include a methoxy group and an ethoxy group. As the halogen atom, chlorine and bromine are preferable, and chlorine is more preferable. As the alkoxycarbonyl group, methoxycarbonyl and ethoxycarbonyl are preferable, and methoxycarbonyl is more preferable. The substituents in the substituted alkoxy group and the substituted alkoxycarbonyl group are the same as those described for the substituent of the substituted alkyl group.

Specific examples of preferred aryl groups as R _{3 to} R ₁₀ and R _{19 to} R ₂₆ include those in which 1 to 3 benzene rings form a condensed ring, and a benzene ring and a 5-membered unsaturated ring form a condensed ring. Specific examples include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, and a fluorenyl group. Among these, a phenyl group and a naphthyl group are exemplified. More preferred.

Specific examples of the substituent of the substituted aryl group preferable as R _{3 to} R ₁₀ and R _{19 to} R ₂₆ include a monovalent nonmetallic atomic group as a substituent on the ring-forming carbon atom of the aryl group. What you have is used. Examples of preferred substituents include the alkyl groups, substituted alkyl groups, and those previously shown as substituents in the substituted alkyl group. Preferred examples of such a substituted aryl group include biphenyl group, tolyl group, xylyl group, mesityl group, cumenyl group, chlorophenyl group, bromophenyl group, fluorophenyl group, chloromethylphenyl group, trifluoromethylphenyl group. Hydroxyphenyl group, methoxyphenyl group, methoxyethoxyphenyl group, allyloxyphenyl group, phenoxyphenyl group, methylthiophenyl group, tolylthiophenyl group, ethylaminophenyl group, diethylaminophenyl group, morpholinophenyl group, acetyloxyphenyl group, Benzoyloxyphenyl group, N-cyclohexylcarbamoyloxyphenyl group, N-phenylcarbamoyloxyphenyl group, acetylaminophenyl group, N-methylbenzoylaminophenyl group, cal Xiphenyl group, methoxycarbonylphenyl group, allyloxycarbonylphenyl group, chlorophenoxycarbonylphenyl group, carbamoylphenyl group, N-methylcarbamoylphenyl group, N, N-dipropylcarbamoylphenyl group, N- (methoxyphenyl) carbamoylphenyl group N-methyl-N- (sulfophenyl) carbamoylphenyl group, sulfophenyl group, sulfonatophenyl group, sulfamoylphenyl group, N-ethylsulfamoylphenyl group, N, N-dipropylsulfamoylphenyl group, N-tolylsulfamoylphenyl group, N-methyl-N- (phosphonophenyl) sulfamoylphenyl group, phosphonophenyl group, phosphonatophenyl group, diethylphosphonophenyl group, diphenylphosphoro Phenyl group, methylphosphonophenyl group, methylphosphonatophenyl group, tolylphosphonophenyl group, tolylphosphonatophenyl group, allylphenyl group, 1-propenylmethylphenyl group, 2-butenylphenyl group, 2-methylallylphenyl Group, 2-methylpropenylphenyl group, 2-propynylphenyl group, 2-butynylphenyl group, 3-butynylphenyl group, and the like.

As the heteroaryl group, a group derived from a monocyclic or polycyclic aromatic ring containing at least one of nitrogen, oxygen and sulfur atoms is used, and examples of the heteroaryl ring in the particularly preferred heteroaryl group include Is, for example, thiophene, thiathrene, furan, pyran, isobenzofuran, chromene, xanthene, phenoxazine, pyrrole, pyrazole, isothiazole, isoxazole, pyrazine, pyrimidine, pyridazine, indolizine, isoindolizine, indolizine, indazole, indazole, Purine, quinolidine, isoquinoline, phthalazine, naphthyridine, quinazoline, sinoline, pteridine, carbazole, carboline, phenanthrine, acridine, perimidine, phenanthrolin, phthalazine, phenalazine, phenoxazine, fura Emissions, phenoxazine and the like, and these may be benzo-fused.
The substituent of the substituted heteroaryl group is the same as that described for the substituent of the substituted aryl group.

R ₁₇ and R ₁₈ are preferably a substituted or unsubstituted alkyl group, and preferred examples thereof are the same as those described for R ₁ above.

  Although the preferable specific example (Exemplary compound D1-Exemplary compound D21) of the sensitizing dye represented by general formula (I) based on this invention is shown below, this invention is not limited to these.

The sensitizing dye represented by formula (I) can be synthesized by a known method. Hereinafter, a method for synthesizing Compound D-1 will be specifically described.
(Synthesis method)
17.3 g of 2-methylene-1,3,3-trimethylindolenine was mixed with 40 ml of toluene at room temperature, and 8.3 ml of pyridine was added, followed by stirring at room temperature for 20 minutes. Next, 5 g of triphosgene was dissolved in 20 ml of toluene and slowly added dropwise under ice cooling. After dropping, the temperature was raised to room temperature and stirred for 1 hour. To the reaction solution stirred at room temperature for 1 hour, a saturated sodium bicarbonate solution was added dropwise until no foaming occurred to quench triphosgene. Subsequently, 200 ml of water was added and extracted with ethyl acetate. The organic phase of ethyl acetate-toluene was washed with an aqueous sodium chloride solution and then with water. After washing, the organic phase was concentrated to give a dark purple solid. The obtained solid was reslurried with methanol and then recrystallized with acetone to obtain 2 g of the target compound D-1.

The sensitizing dye represented by the general formula (I) used in the present invention can be further subjected to various chemical modifications for improving the characteristics of the photosensitive layer. For example, by combining a sensitizing dye and an addition polymerizable compound structure (for example, an acryloyl group or a methacryloyl group) by a method such as a covalent bond, an ionic bond, or a hydrogen bond, the exposure film has a higher strength, the dye It is possible to suppress the precipitation of.
In addition, partial structures having a radical generating ability in sensitizing dyes and initiator compounds described later (for example, reductive decomposable sites such as alkyl halides, oniums, peroxides, biimidazoles, oniums, borate, amines, trimethylsilylmethyls) , An oxidatively cleavable site such as carboxymethyl, carbonyl, imine, etc.), the photosensitivity can be remarkably enhanced particularly in a state where the concentration of the starting system is low.

Furthermore, introduction of hydrophilic sites (carboxyl groups and their esters, sulfonic acid groups and their esters, ethylene oxide groups and other acid groups or polar groups) is effective for the purpose of improving the processing suitability in aqueous developers. It is. In particular, ester-type hydrophilic groups have a relatively hydrophobic structure in the photosensitive layer, so that they have excellent compatibility, and in the developer, acid groups are generated by hydrolysis, resulting in increased hydrophilicity. Have.
In addition, for example, a substituent can be appropriately introduced in order to improve compatibility in the photosensitive layer and to suppress crystal precipitation. For example, in certain types of photosensitive systems, unsaturated bonds such as aryl groups and allyl groups may be very effective in improving compatibility. By introducing an obstacle, crystal precipitation can be remarkably suppressed. Further, by introducing a phosphonic acid group, an epoxy group, a trialkoxysilyl group, etc., adhesion to an inorganic substance such as a metal or a metal oxide can be improved. In addition, a method such as polymerization of a sensitizing dye can be used depending on the purpose.

The sensitizing dye used in the present invention may be a sensitizing dye represented by the above general formula (I), and as long as it is used, for example, a dye having any structure, such as those subjected to the above-described modification The details of the method of use, such as whether or not to be used alone or in combination of two or more, and the amount added, can be appropriately set according to the performance design of the final lithographic printing plate precursor. For example, the compatibility with the photosensitive layer can be increased by using two or more sensitizing dyes in combination.
In selecting the sensitizing dye, in addition to the photosensitivity, the molar extinction coefficient at the emission wavelength of the light source used is an important factor. By using a dye having a large molar extinction coefficient, the amount of the dye added can be made relatively small, which is economical and advantageous from the viewpoint of film properties of the photosensitive layer.
In the present invention, in addition to the sensitizing dye having the specific structure, other general-purpose sensitizing dyes can be used in combination as long as the effects of the present invention are not impaired.

The photosensitivity and resolution of the photosensitive layer, or the physical properties of the exposed film are greatly affected by the absorbance at the light source wavelength, and thus the addition amount of the sensitizing dye is appropriately selected in consideration of these. For example, the sensitivity decreases in a low region where the absorbance is 0.1 or less. Also, the resolution becomes low due to the influence of halation. However, for the purpose of curing a thick film of, for example, 5 μm or more, there is a case where such a low absorbance can be increased instead. Further, in a region where the absorbance is as high as 3 or more, most of the light is absorbed on the surface of the photosensitive layer, the curing inside is further inhibited, and the printing plate has insufficient film strength and substrate adhesion. Become.
For example, when the sensitizing dye of the present invention is used in a photosensitive layer having a relatively thin film thickness, the addition amount of the sensitizing dye is such that the absorbance of the photosensitive layer is in the range of 0.1 to 1.5, preferably 0. It is preferably set to be in the range of 25 to 1. Since the absorbance is determined by the addition amount of the sensitizing dye and the thickness of the photosensitive layer, the predetermined absorbance can be obtained by controlling both conditions. The absorbance of the photosensitive layer can be measured by a conventional method. As a measuring method, for example, on a transparent or white support, a photosensitive layer having a thickness appropriately determined in a range where the coating amount after drying is necessary as a lithographic printing plate is formed, and measured with a transmission type optical densitometer. And a method of forming a photosensitive layer on a reflective support such as aluminum and measuring the reflection density.
The addition amount of the sensitizing dye having a specific structure in the present invention is usually 0.05 to 30 parts by mass, preferably 0.1 to 20 parts by mass, and more preferably 100 to 20 parts by mass with respect to 100 parts by mass of the total solid components constituting the photosensitive layer. Preferably it is the range of 0.2-10 mass parts.

  Since the sensitizing dye represented by the general formula (I) of the present invention is excellent in dispersibility in the developer in the system of the present invention in which the development treatment is performed with a developer having a pH of 2 to 10, the development residue is reduced. It has characteristics that are difficult to occur.

(B) Initiator Compound The initiator compound in the present invention is a compound that undergoes a chemical change by interacting with the electronically excited state of the sensitizing dye and generates at least one of radical, acid, and base. . Hereinafter, radicals, acids, and bases generated in this way are simply referred to as active species. When these compounds are not present, or when only the initiator compound is used alone, practically sufficient sensitivity cannot be obtained. As one embodiment in which the sensitizing dye and the initiator compound are used in combination, these may be used as a single compound by an appropriate chemical method (such as linking by a chemical bond between the sensitizing dye and the initiator compound). Is possible. Such a technical idea is disclosed in, for example, Japanese Patent Publication No. 27-20195.

  Usually, many of these initiator compounds are considered to generate active species through the following initial chemical process (a) to (c). (A) Reductive decomposition of the initiator compound based on the electron transfer reaction from the electronically excited state of the sensitizing dye to the initiator compound, (b) Electron transfer from the initiator compound to the electronically excited state of the sensitizing dye (C) decomposition of the initiator compound from the electronically excited state based on energy transfer from the electronically excited state of the sensitizing dye to the initiator compound. Although it is often ambiguous as to which type (a) to (c) each initiator compound belongs, the major feature of the sensitizing dye in the present invention is a combination with any of these types of initiator compounds. However, it has a very high sensitizing effect.

  Specific initiator compounds known to those skilled in the art can be used without limitation. Specifically, for example, Bruce M. Monroe et al., Chemical Revue, 93, 435 (1993) and RSDavidson, Journal of Photochemistry and Biology A: Chemistry, 73. 81 (1993), JPF Faussier "Photoinitiated Polymerization-Theory and Applications": Rapra Review vol. 9, Report, Rapra Technology (1998), M. Tsunooka et al., Prog. Polym. Many are described in Sci., 21, 1 (1996). In addition, as other compound groups having the functions of (a) and (b), FDSaeva, Topics in Current Chemistry, 156, 59 (1990), GG Maslak, Topics in Current Chemistry, 168, 1 ( 1993), HBShuster et al, JACS, 112, 6329 (1990), IDFEaton et al, JACS, 102, 3298 (1980), etc., resulting in oxidative or reductive bond cleavage Compound groups are also known.

In the following, specific examples of preferred initiator compounds are: (a) those that are reduced to cause bond cleavage to generate active species, (b) those that can be oxidized to cause bond cleavage to generate active species, (c )
Although it will be described as being classified into others, there are many cases where there is no general rule as to which individual compound belongs, and the present invention is not limited by the description of these reaction mechanisms.

(A) Those that are reduced to cause bond cleavage and generate active species.
Compound having a carbon-halogen bond: It is considered that a carbon-halogen bond is reductively cleaved to generate an active species (for example, described in Polymer Preprints, Jpn., 41 (3) 542 (1992)). . As the active species, radicals and acids can be generated. Specifically, for example, in addition to halomethyl-s-triazines, halomethyl oxazines which can be easily synthesized by those skilled in the art by the synthesis method described in Journal of Heterocyclic chemistry, 7,511 (1970) by MPHutt, EFElslager and LMMerbel. Further, azoles and compounds described in German Patent Nos. 2641100, 3333450, 3021590, and 3021599 can be preferably used.

  Compounds having a nitrogen-nitrogen bond or nitrogen-containing heterocycle-nitrogen-containing heterocycle bond: reductive bond cleavage (for example, described in J.Pys.Chem., 96,207 (1992)). Specifically, hexaarylbiimidazoles and the like are preferably used. The active species produced are lophine radicals, which together with a hydrogen donor if necessary, initiate radical chain reactions, and image formation using oxidation reactions with lophine radicals is also known (J. Imaging Sci., 30, 215). (1986)).

  Compound having oxygen-oxygen bond: It is considered that the oxygen-oxygen bond is reductively cleaved to generate an active radical (for example, described in Polym. Adv. Technol., 1,287 (1990)). Specifically, for example, organic peroxides are preferably used. A radical can be generated as an active species.

  Onium compound: It is considered that a carbon-hetero bond or an oxygen-nitrogen bond is reductively cleaved to generate an active species (for example, described in J. Photopolym. Sci. Technol., 3, 149 (1990)). . Specifically, for example, iodonium salts described in European Patent No. 104143, U.S. Pat. No. 4,837,124, Japanese Patent Laid-Open No. 2-150848, and Japanese Patent Laid-Open No. 2-96514, European Patent Nos. 370693, 233567, 297443, 293442, 279210, 422570, U.S. Pat. Nos. 3,902,144, 4,933,377, 4,760013, 4,734,344 and 2,833,827, sulfonium salts and diazonium salts (which may have a substituent) Diazonium, etc.), diazonium salt resins (formaldehyde resin of diazodiphenylamine, etc.), N-alkoxypyridinium salts, etc. (eg, USP 4,743,528, JP-A 63-138345, JP-A 63-142345, Kaisho 63 142346, Japanese Patent Publication No. 46-42363, etc., specifically 1-methoxy-4-phenylpyridinium tetrafluoroborate, etc.), and further, Japanese Patent Publication Nos. 52-147277, 52-14278, The compounds described in No. 52-14279 are preferably used. Generates radicals and acids as active species.

  Active esters: nitrobenzyl esters of sulfonic acid or carboxylic acid, esters of sulfonic acid or carboxylic acid with N-hydroxy compounds (N-hydroxyphthalimide, oxime, etc.), sulfonic acid esters of pyrogallol, naphthoquinone diazide-4 -Sulfonates can be reductively decomposed. As the active species, radicals and acids can be generated. Specific examples of the sulfonic acid esters include European Patent Nos. 0290750, 046083, 1156153, 271851, 0388343, U.S. Pat. Nos. 3,901,710 and 4,181,531, Japanese Patent Laid-Open No. 60-198538. Nitrobenzester compounds described in JP-A-53-133022, European Patents 0196672, 84515, 199672, 044115, 0101122, US Pat. Nos. 4,618,564, 4371605, and 4431774, The iminosulfonate compounds described in JP-A No. 64-18143, JP-A-2-245756, JP-A-4-365048, JP-B-62-2223, JP-B-63-14340, JP-A-59-174831 Compounds, etc. For example compounds may be mentioned below.

(In the formula, Ar represents an aromatic group which may be substituted, or an aliphatic group which may be substituted.)
Moreover, it is also possible to produce | generate a base as an active species, for example, the following compound groups are known.

  Ferrocene and iron arene complexes: An active radical can be reductively generated. Specifically, for example, they are disclosed in JP-A-1-304453 and JP-A-1-152109.

(In the formula, R represents an aliphatic group which may be substituted, or an aromatic group which may be substituted.)
Disulfones: Reducing S—S bond reductively and generating an acid. For example, diphenyl disulfones as described in JP-A 61-166544 are known.

(B) Those that are oxidized to cause bond cleavage and generate active species.
Alkylate complex: It is considered that a carbon-hetero bond is oxidatively cleaved to generate an active radical (for example, as described in J. Am. Chem. Soc., 112, 6329 (1990)). Specifically, for example, triarylalkyl borates are preferably used.

Alkylamine compound: It is considered that a C—X bond on carbon adjacent to nitrogen is cleaved by oxidation to generate an active radical (for example, J. Am. Chem. Soc., 116, 4211 (1994). As described in). X is preferably a hydrogen atom, a carboxyl group, a trimethylsilyl group, a benzyl group or the like. Specifically, for example, ethanolamines, N-phenylglycines, N
-Trimethylsilylmethylaniline etc. are mentioned.

  Sulfur-containing and tin-containing compounds: Compounds in which the nitrogen atoms of the above-described amines are replaced with sulfur atoms and tin atoms can generate active radicals by the same action. Further, a compound having an SS bond is also known to be sensitized by SS cleavage.

  α-Substituted methylcarbonyl compound: An active radical can be generated by oxidative cleavage of the carbonyl-α carbon bond. Moreover, what converted carbonyl into the oxime ether also shows the same effect | action. Specifically, 2-alkyl-1- [4- (alkylthio) phenyl] -2-morpholinopronone-1 and these and a hydroxylamine were reacted, and then N—OH was etherified. Mention may be made of oxime ethers.

  Sulfinic acid salts: An active radical can be reductively generated. Specific examples include sodium arylsulfinate.

(C) Other sensitization mechanisms are not clear, but many can function as activators. Examples thereof include organometallic compounds such as titanocene and ferrocene, aromatic ketones, acylphosphine, bisacylphosphine and the like, and active species can generate radicals and acids.

  Hereinafter, among the initiator compounds used in the present invention, preferred compounds particularly excellent in sensitivity and stability are specifically exemplified.

(1) Halomethyltriazines:
Examples thereof include compounds represented by the following formula [II]. Excellent radical generation and acid generation ability.

In the formula [II], X represents a halogen atom. Y ¹ represents —CX ′ ₃ , —NH ₂ , —NHR ¹ ′, —NR ¹ ′ ₂ , —OR ¹ ′. Here, R ¹ ′ represents an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group. R ¹ represents —CX ₃ , an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, or a substituted alkenyl group.

  Specific examples of such compounds include, for example, compounds described in Wakabayashi et al., Bull. Chem. Soc. Japan, 42, 2924 (1969), such as 2-phenyl-4,6-bis (trichloromethyl)- S-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -S-triazine, 2 -(P-methoxyphenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (2 ', 4'-dichlorophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -S-triazine, 2-n-nonyl-4,6-bis (trichloromethyl)- S- Triazine, 2- (α, α, β- trichloroethyl) -4,6-bis (trichloromethyl) -S- triazine. In addition, compounds described in GB 1388492, for example, 2-styryl-4,6-bis (trichloromethyl) -S-triazine, 2- (p-methylstyryl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -S-triazine, 2- (p-methoxystyryl) -4-amino-6-trichloromethyl-S-triazine Compounds described in JP-A-53-133428, such as 2- (4-methoxy-naphth-1-yl) -4,6-bis-trichloromethyl-S-triazine, 2- (4-ethoxy-naphtho) -1-yl) -4,6-bis-trichloromethyl-S-triazine, 2- [4- (2-ethoxyethyl) -naphth-1-yl] -4,6-bis-trichloromethyl S-triazine, 2- (4,7-dimethoxy-naphth-1-yl) -4,6-bis-trichloromethyl-S-triazine, 2- (acenaphtho-5-yl) -4,6-bis-trichloro Examples of the compound described in DE 3337024, such as methyl-S-triazine, include the following compounds.

  Further, compounds described in J. Org. Chem., 29, 1527 (1964) by FC Schaefer et al., For example, 2-methyl-4,6-bis (tribromomethyl) -S-triazine, 2,4,6-tris (Tribromomethyl) -S-triazine, 2,4,6-tris (dibromomethyl) -S-triazine, 2-amino-4-methyl-6-tribromomethyl-S-triazine, 2-methoxy-4-methyl And -6-trichloromethyl-S-triazine.

  Further, compounds described in JP-A No. 62-58241, for example, the following compounds can be mentioned.

  Further, compounds described in JP-A-5-281728, for example, the following compounds can be mentioned.

(2) Titanocenes:
The titanocene compound suitably used may be any titanocene compound that can generate an active species when irradiated with light in the presence of the above-described sensitizing dye. For example, JP-A-59-152396. JP, 61-151197, JP 63-41483, JP 63-41484, JP 2-249, JP 2-291, JP 3-27393, JP 3 Known compounds described in JP-A-124033 and JP-A-6-41170 can be appropriately selected and used.

  More specifically, di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,3,4,5 , 6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2 , 4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4 -Difluorophenyl-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl-Ti- Bis-2, 3, , 6-tetrafluorophenyl-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, bis (cyclopentadienyl) -bis (2,6- And difluoro-3- (pyr-1-yl) phenyl) titanium.

(3) Borate salt compound:
Borate salts represented by the following formula [III] are excellent in radical generating ability.

In the formula [III], R ⁵¹ , R ⁵² , R ⁵³ and R ⁵⁴ may be the same or different from each other, and each represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl. A group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted heterocyclic group, wherein R ⁵¹ , R ⁵² , R ^53, and R ⁵⁴ are bonded to form a cyclic structure. Also good. However, at least one of R ⁵¹ , R ⁵² , R ⁵³ and R ⁵⁴ is a substituted or unsubstituted alkyl group. Z ⁺ represents an alkali metal cation or a quaternary ammonium cation.

The alkyl groups of R ^{51 to} R ⁵⁴ include straight chain, branched, and cyclic groups, and those having 1 to 18 carbon atoms are preferable. Specifically, methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, octyl, stearyl, cyclobutyl, cyclopentyl, cyclohexyl and the like are included. Examples of the substituted alkyl group include the above alkyl groups, halogen atoms (for example, -Cl, -Br, etc.), cyano groups, nitro groups, aryl groups (preferably phenyl groups), hydroxy groups, the following groups,

(Here, R ⁵⁵ and R ⁵⁶ independently represent a hydrogen atom, an alkyl group having 1 to 14 carbon atoms, or an aryl group.), —COOR ⁵⁷ (wherein R ⁵⁷ represents a hydrogen atom, having 1 to 14 carbon atoms. an alkyl group or an aryl group,), -. COOR ⁵⁸ or -OR ⁵⁹ (wherein R ⁵⁸ is included those having as a substituent a) an alkyl group or an aryl group, 1 to 14 carbon atoms..

Examples of the aryl group of R ^{51 to} R ⁵⁴ include 1 to 3 ring aryl groups such as a phenyl group and a naphthyl group, and examples of the substituted aryl group include the substitution of the above substituted alkyl group with the above aryl group. And those having an alkyl group having 1 to 14 carbon atoms.

Examples of the alkenyl group represented by R ^{51 to} R ⁵⁴ include linear, branched, and cyclic groups having 2 to 18 carbon atoms, and examples of the substituent of the substituted alkenyl group include the substituents of the substituted alkyl group. Is included.

Examples of the alkynyl group of R ^{51 to} R ⁵⁴ include linear or branched groups having 2 to 28 carbon atoms, and examples of the substituent of the substituted alkynyl group include those listed as the substituent of the substituted alkyl group. included.

In addition, examples of the heterocyclic group of R ^{51 to} R ⁵⁴ include a 5- or more-membered heterocyclic group containing at least one of N, S and O, preferably a 5- to 7-membered heterocyclic group. May contain a condensed ring. Furthermore, you may have what was mentioned as a substituent of the above-mentioned substituted aryl group as a substituent.

  Specific examples of the compound represented by the formula [III] include compounds described in U.S. Pat. Nos. 3,567,453 and 4,434,891, European Patent Nos. 109772 and 109773, and those shown below.

(4) Hexaarylbiimidazoles:
Excellent stability and highly sensitive radical generation is possible. Specifically, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-bromophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (m-methoxyphenyl) biimidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5,5'-tetraphenylbiimidazole 2,2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5,5 '-Tetraphenylbiimidazole, 2,2'-bis (o-trifluoromethyl Eniru) -4,4 ', 5,5'-tetraphenyl biimidazole.

(5) Onium salt compound:
15 (5B), 16 (6B), and 17 (7B) group elements of the periodic table, specifically, onium compounds of N, P, As, Sb, Bi, O, S, Se, Te, and I are sensitive. Excellent activators, particularly iodonium salts and sulfonium salts, especially diaryl iodonium and triaryl sulfonium salt compounds, are extremely excellent in terms of both sensitivity and storage stability. Acids and / or radicals can be generated, and these can be used properly by appropriately selecting the use conditions according to the purpose. Specific examples include the following compounds.

(6) Organic peroxide:
When an organic peroxide type initiator compound is used, radicals as active species can be generated with very high sensitivity.

  The organic peroxide includes almost all organic compounds having one or more oxygen-oxygen bonds in the molecule. Examples thereof include methyl ethyl ketone peroxide, cyclohexanone peroxide, and 3,3,5-trimethylcyclohexanone. Peroxide, methylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2, 2-Bis (t-butylperoxy) butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paraffin hydroperoxide, 2,5-dimethylhexane-2,5-dihydride Peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, bis (t-butylperoxyisopropyl) benzene, 2 , 5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, acetyl peroxide, isobutyryl peroxide, Octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, meta-toluoyl peroxide , Diisopropyl peroxy dicarbonate Di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, dimethoxyisopropyl peroxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, t-butyl peroxyacetate , T-butylperoxypivalate, t-butylperoxyneodecanoate, t-butylperoxyoctanoate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy Laurate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylmaleic acid, t-butylper Oxyisopropyl carbonate, 3,3 ', 4,4'-te La- (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (t-amylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-hexylper Oxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-octylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (cumylperoxycarbonyl) benzophenone, 3,3 ′, There are 4,4′-tetra (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogendiphthalate), carbonyldi (t-hexylperoxydihydrogendiphthalate), and the like.

  Among these, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (t-amylperoxycarbonyl) benzophenone, 3 , 3 ′, 4,4′-tetra (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (t-octylperoxycarbonyl) benzophenone, 3,3 ′, 4,4 ′ Peroxide esters such as tetra (cumylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra (p-isopropylcumylperoxycarbonyl) benzophenone, di-t-butyldiperoxyisophthalate are preferred. .

  Of these initiator compounds, halomethyltriazines and hexaarylbiimidazoles are preferable in terms of excellent sensitivity, and particularly preferable initiator compounds are hexaarylbiimidazoles.

  The initiator compound described above can also be subjected to various chemical modifications for improving the characteristics of the photosensitive layer as in the case of the sensitizing dye. For example, bonding with sensitizing dyes, addition-polymerizable unsaturated compounds and other initiator compound parts, introduction of hydrophilic sites, compatibility improvement, introduction of substituents for suppressing crystal precipitation, substituents for improving adhesion Methods such as introduction and polymerization can be used.

  The use method of these initiator compounds can be arbitrarily set arbitrarily according to the performance design of the lithographic printing plate precursor as in the above-described sensitizing dye. For example, by using two or more kinds in combination, the compatibility with the photosensitive layer can be increased. A larger amount of the initiator compound is usually advantageous in terms of photosensitivity, and is used in a range of 0.5 to 80 parts by mass, preferably 1 to 50 parts by mass with respect to 100 parts by mass of the photosensitive layer component. Sufficient photosensitivity can be obtained. On the other hand, when the initiator compound itself has absorption in visible light, such as a titanocene compound, the amount used is from the viewpoint of preventing fogging by light near 500 nm when used under a yellow or white light. The amount of the initiator compound used in combination with the sensitizing dye of the present invention is preferably 6 parts by mass or less, further 1.9 parts by mass or less, and further 1. Even if it is lowered to 4 parts by mass or less, sufficient photosensitivity can be obtained.

(C) Polymerizable compound The polymerizable compound used in the photosensitive layer in the invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and preferably has at least one terminal ethylenically unsaturated bond, preferably It is selected from compounds having two or more. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, ie dimers, trimers and oligomers, or copolymers thereof and mixtures thereof. Examples of monomers include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof, preferably unsaturated carboxylic acids. An ester of an acid and an aliphatic polyhydric alcohol compound and an amide of an unsaturated carboxylic acid and an aliphatic polyamine compound are used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, isocyanuric acid ethylene oxide (EO) Examples include modified triacrylates and polyester acrylate oligomers.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

  Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate Sorbitol tetritaconate, etc. Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, JP-A-59- Those having an aromatic skeleton described in JP-A No. 5241 and JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

  Further, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable. Specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinylurethane compound containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (A) to a polyisocyanate compound having two or more isocyanate groups Etc.

_{CH 2 = C (R 4)} COOCH 2 CH (R 5) OH (A)
(However, R ₄ and R ₅ represent H or CH _3. )

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56- Urethane compounds having an ethylene oxide skeleton described in Japanese Patent No. 17654, Japanese Patent Publication No. 62-39417, and Japanese Patent Publication No. 62-39418 are also suitable. Furthermore, addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 are used. Depending on the case, it is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-A-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid-based compounds described in JP-A-2-25493 are also included. Can be mentioned. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

About these polymerizable compounds, the details of usage such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable. Further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
In addition, the compatibility and dispersibility with other components in the photosensitive layer (for example, binder polymer, polymerization initiator, colorant, etc.), the selection and use method of the polymerizable compound is an important factor. In some cases, the compatibility can be improved by using a low-purity compound or by using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving adhesion to a support or a protective layer described later.

  The polymerizable compound is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass, based on the total solid content of the photosensitive layer. These may be used alone or in combination of two or more. In addition, the usage of the polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. The layer construction and coating method such as undercoating and overcoating are also considered.

(D) Hydrophobic binder polymer having an acid value of 0.3 meq / g or less As the hydrophobic binder polymer having an acid value of 0.3 meq / g or less used in the photosensitive layer of the present invention, a water-insoluble polymer is preferably used. . Furthermore, the thing which does not contain acid groups, such as a carboxyl group, a sulfo group, and a phosphate group substantially, is preferable. Acid value of the binder polymer (the acid content per gram of the polymer is expressed in terms of the number of chemical equivalents. The acid value of the binder polymer is preferably 0.1 meq / g or less.
That is, the hydrophobic binder polymer used in the present invention is preferably insoluble in water and an aqueous solution having a pH of 10 or more. The solubility of the hydrophobic binder polymer in water and an aqueous solution having a pH of 10 or more (polymer concentration at saturation dissolution) is preferably 0.5% by mass or less, and more preferably 0.1% by mass or less. By using such a hydrophobic binder polymer, the film strength, water resistance, and inking property of the photosensitive layer are improved, and printing durability is improved. The solubility measurement temperature is 25 ° C., which is substantially the same as the temperature during plate-making development.

As the hydrophobic binder polymer, as long as the performance of the lithographic printing plate of the present invention is not impaired, a conventionally known one can be used without limitation within the above range, and a linear organic polymer having a film property is preferable.
As an example of such a hydrophobic binder polymer, a polymer selected from acrylic resin, polyvinyl acetal resin, polyurethane resin, polyamide resin, epoxy resin, methacrylic resin, styrene resin, and polyester resin is preferable. Especially, an acrylic resin is preferable and a (meth) acrylic acid ester copolymer is preferable. More specifically, an alkyl (meth) acrylate or an aralkyl ester and an ester residue (—COOR) of (meth) acrylate ester may have —CH ₂ CH ₂ O— unit or —CH ₂ CH ₂ NH— unit as R. A copolymer with a (meth) acrylic acid ester containing is particularly preferred. The preferable alkyl group of the (meth) acrylic acid alkyl ester is an alkyl group having 1 to 5 carbon atoms, and a methyl group is more preferable. Preferable (meth) acrylic acid aralkyl esters include benzyl (meth) acrylate.

Furthermore, the hydrophobic binder polymer can be provided with a crosslinking property in order to improve the film strength of the image area.
In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization or may be introduced by a polymer reaction.

  Here, the crosslinkable group is a group that crosslinks the polymer binder in the process of radical polymerization reaction that occurs in the photosensitive layer when the lithographic printing plate precursor is exposed. Although it will not specifically limit if it is a group of such a function, For example, an ethylenically unsaturated bond group, an amino group, an epoxy group etc. are mentioned as a functional group which can be addition-polymerized. Moreover, the functional group which can become a radical by light irradiation may be sufficient, and as such a crosslinkable group, a thiol group, a halogen group, an onium salt structure etc. are mentioned, for example. Especially, an ethylenically unsaturated bond group is preferable and the functional group represented by the following general formula (1)-(3) is especially preferable.

In the general formula (1), R ^{1 to} R ³ each independently represents a hydrogen atom or a monovalent organic group, and R ¹ is preferably a hydrogen atom or an alkyl which may have a substituent. A hydrogen atom or a methyl group is preferable because of high radical reactivity. R ² and R ³ are each independently a hydrogen atom, a halogen atom, an amino group, a carboxyl group, an alkoxycarbonyl group, a sulfo group, a nitro group, a cyano group, an optionally substituted alkyl group, or a substituted group. An aryl group which may have a group, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an alkylamino group which may have a substituent, and a substituent An arylamino group which may have a substituent, an alkylsulfonyl group which may have a substituent, an arylsulfonyl group which may have a substituent, and the like. Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, a substituent An alkyl group which may have a substituent and an aryl group which may have a substituent are preferable because of high radical reactivity.

X represents an oxygen atom, a sulfur atom, or —N— (R ¹² ), and R ¹² represents a hydrogen atom or a monovalent organic group. Here, examples of the monovalent organic group include an alkyl group which may have a substituent, and in particular, R ¹² is a hydrogen atom, a methyl group, an ethyl group, or an isopropyl group having a high radical reactivity. To preferred.

  Here, examples of the substituent that can be introduced include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom, an amino group, an alkylamino group, an arylamino group, a carboxyl group, an alkoxycarbonyl group, A sulfo group, a nitro group, a cyano group, an amide group, an alkylsulfonyl group, an arylsulfonyl group and the like can be mentioned.

In the general formula (2), R ^{4 to} R ⁸ each independently represents a hydrogen atom or a monovalent organic group, and R ^{4 to} R ⁸ are preferably a hydrogen atom, a halogen atom, an amino group, or a dialkyl. Amino group, carboxyl group, alkoxycarbonyl group, sulfo group, nitro group, cyano group, alkyl group which may have a substituent, aryl group which may have a substituent, alkoxy which may have a substituent A group, an aryloxy group which may have a substituent, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, an alkylsulfonyl group which may have a substituent, Examples include an arylsulfonyl group which may have a substituent. Among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, an alkyl group which may have a substituent, and an aryl which may have a substituent The ru group is preferred.

Examples of the substituent that can be introduced are the same as those in the general formula (1). Y represents an oxygen atom, a sulfur atom, or N (R ¹² ) —. R ¹² has the same meaning as R ¹² in general formula (1), and preferred examples are also the same.

In the general formula (3), R ⁹ represents a hydrogen atom or a monovalent organic group, and preferably includes a hydrogen atom or an alkyl group which may have a substituent. A methyl group is preferred because of high radical reactivity. R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a halogen atom, an amino group, a dialkylamino group, a carboxyl group, an alkoxycarbonyl group, a sulfo group, a nitro group, a cyano group, or an alkyl group which may have a substituent. An aryl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an alkylamino group which may have a substituent, a substituent An arylamino group that may have, an alkylsulfonyl group that may have a substituent, an arylsulfonyl group that may have a substituent, and the like, among them, a hydrogen atom, a carboxyl group, an alkoxycarbonyl group, An alkyl group which may have a substituent and an aryl group which may have a substituent are preferable because of high radical reactivity.

Here, examples of the substituent that can be introduced are the same as those in the general formula (1). Further, Z is an oxygen atom, a sulfur atom, -N (R ¹³⁾ -, or a phenylene group which may have a substituent. Examples of R ¹³ include an alkyl group which may have a substituent. Among them, a methyl group, an ethyl group, and an isopropyl group are preferable because of high radical reactivity.
Among these, (meth) acrylic copolymers and polyurethanes having a crosslinkable group in the side chain are more preferred.

  Hydrophobic binder polymers having crosslinkability include, for example, free radicals (polymerization initiation radicals or growth radicals in the polymerization process of a polymerizable compound) added to the crosslinkable functional group, and polymerization of polymerizable compounds directly between polymers. Addition polymerization through a chain forms a cross-link between polymer molecules and cures. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded to each other so that crosslinking between the polymer molecules occurs. Forms and cures.

  The content of the crosslinkable group in the hydrophobic binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1 g per 1 g of the hydrophobic binder polymer. Is 1.0 to 7.0 mmol, most preferably 2.0 to 5.5 mmol.

The hydrophobic binder polymer preferably has a mass average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 250,000. Is more preferable. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The hydrophobic binder polymer may be any of a random polymer, a block polymer, a graft polymer, and the like, but is preferably a random polymer.

  The hydrophobic binder polymer may be used alone or in combination of two or more. The content of the hydrophobic binder polymer is usually 5 to 90% by mass, preferably 10 to 70% by mass, and more preferably 10 to 60% by mass with respect to the total solid content of the photosensitive layer. . Within this range, good image area strength and image formability can be obtained.

(E) Co-sensitizer The sensitivity of the photosensitive layer can be further improved by using a certain additive (hereinafter referred to as a co-sensitizer). These mechanisms of action are not clear, but many are thought to be based on the following chemical processes. That is, co-amplification with various intermediate active species (radicals, peroxides, oxidizing agents, reducing agents, etc.) generated in the course of the photoreaction initiated by light absorption of the above-mentioned photoinitiating system and the subsequent addition polymerization reaction. It is presumed that the sensitizer reacts to generate new active radicals. These can be broadly divided into (a) those that can be reduced to generate active radicals, (b) those that can be oxidized to generate active radicals, and (c) radicals that are more active by reacting with less active radicals. Can be categorized as those that act as chain transfer agents, but there is often no generality as to which of these individual compounds belong.

(A) Compound that is reduced to produce an active radical Compound having a carbon-halogen bond: It is considered that the carbon-halogen bond is reductively cleaved to generate an active radical. Specifically, for example, trihalomethyl-s-triazines and trihalomethyloxadiazoles can be preferably used.

  Compound having nitrogen-nitrogen bond: It is considered that the nitrogen-nitrogen bond is reductively cleaved to generate an active radical. Specifically, hexaarylbiimidazoles and the like are preferably used.

  Compound having oxygen-oxygen bond: It is considered that the oxygen-oxygen bond is reductively cleaved to generate an active radical. Specifically, for example, organic peroxides are preferably used.

Onium compounds: It is considered that carbon-hetero bonds and oxygen-nitrogen bonds are reductively cleaved to generate active radicals. Specifically, for example, diaryliodonium salts, triarylsulfonium salts, N-alkoxypyridinium (azinium) salts and the like are preferably used.
Ferrocene and iron arene complexes: An active radical can be reductively generated.

(B) Compound which is oxidized to generate an active radical Alkylate complex: It is considered that a carbon-hetero bond is oxidatively cleaved to generate an active radical. Specifically, for example, triarylalkyl borates are preferably used.

  Alkylamine compound: It is considered that the C—X bond on carbon adjacent to nitrogen is cleaved by oxidation to generate an active radical. X is preferably a hydrogen atom, a carboxyl group, a trimethylsilyl group, a benzyl group or the like. Specific examples include ethanolamines, N-phenylglycines, N-trimethylsilylmethylanilines, and the like.

  Sulfur-containing and tin-containing compounds: Compounds in which the nitrogen atoms of the above-described amines are replaced with sulfur atoms and tin atoms can generate active radicals by the same action. Further, a compound having an SS bond is also known to be sensitized by SS cleavage.

α-Substituted methylcarbonyl compound: An active radical can be generated by oxidative cleavage of the carbonyl-α carbon bond. Moreover, what converted carbonyl into the oxime ether also shows the same effect | action. Specifically, 2-alkyl-1- [4- (alkylthio) phenyl] -2-morpholinopronone-1 and these and a hydroxylamine were reacted, and then N—OH was etherified. Mention may be made of oxime ethers.

  Sulfinic acid salts: An active radical can be reductively generated. Specific examples include sodium arylsulfinate.

c) Compounds that react with radicals to convert to highly active radicals or act as chain transfer agents, for example, compounds having SH, PH, SiH, GeH in the molecule are used. These can donate hydrogen to low-activity radical species to generate radicals, or can be oxidized and then deprotonated to generate radicals. Specifically, 2-mercaptobenzimidazoles etc. are mentioned, for example.

  Many more specific examples of these co-sensitizers are described, for example, in JP-A-9-236913 as additives for the purpose of improving sensitivity. Some examples are shown below, but the present invention is not limited thereto. -TMS is a trimethylsilyl group.

  Of the co-sensitizers, chain transfer agents are particularly preferred. Chain transfer agents contribute to improved sensitivity and storage stability.

In the photosensitive layer of the present invention, in particular, a thiol compound (for example, 2-mercaptobenzimidazoles) can be preferably used as a chain transfer agent.
Especially, the thiol compound represented by the following general formula (I) is used especially suitably. By using this thiol compound as a chain transfer agent, the problem of odor and sensitivity reduction due to evaporation from the photosensitive layer and diffusion to other layers are avoided, and it has excellent storage stability and high sensitivity and high printing durability. A lithographic printing plate precursor is obtained.

  In general formula (I), R represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and A represents a 5-membered ring having a carbon atom together with an N = CN moiety or It represents an atomic group that forms a 6-membered heterocycle, and A may further have a substituent.

  More preferably, a compound represented by the following general formula (IA) or general formula (IB) is used.

  In general formula (IA) and formula (IB), R represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and X may have a halogen atom or a substituent. Represents a good alkoxyl group, an alkyl group which may have a substituent, or an aryl group which may have a substituent.

  Specific examples of the compound represented by formula (I) are shown below, but the present invention is not limited to these.

  The amount of the thiol compound used is preferably 0.01 to 20% by mass, more preferably 0.1 to 15% by mass, based on the total solid content of the photosensitive layer. More preferably, it is 1.0-10 mass%.

  With respect to the co-sensitizer, as in the case of the sensitizing dye, various chemical modifications for improving the characteristics of the photosensitive layer can be performed. For example, sensitizing dye, initiator compound, polymerizable compound, bonding with other parts, introduction of hydrophilic sites, compatibility improvement, substituent introduction for suppressing crystal precipitation, substituent introduction for improving adhesion, Methods such as polymerization can be used.

  A co-sensitizer can be used individually or in combination of 2 or more types. The amount used is suitably 0.05 to 100 parts by weight, preferably 1 to 80 parts by weight, and more preferably 3 to 50 parts by weight with respect to 100 parts by weight of the polymerizable compound.

<Microcapsule>
In the present invention, as a method for causing the photosensitive layer to contain the above-described photosensitive layer constituents and other constituents described later, for example, as described in JP-A Nos. 2001-277740 and 2001-277742, A part of the components can be encapsulated in microcapsules and added to the photosensitive layer. In that case, each component can be contained in any ratio in and out of the microcapsule.

  As a method for microencapsulating the photosensitive layer constituent components, known methods can be applied. For example, as a method for producing microcapsules, a method using coacervation found in US Pat. Nos. 2,800,547 and 2,800,498, each specification of US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, 42-446 by the interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304 by precipitation of polymer, US Pat. No. 3,796,669, isocyanate polyol A method using a wall material, a method using an isocyanate wall material found in US Pat. No. 3,914,511, and a urea-formaldehyde system found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802. Or urea formaldehyde-resorcino A method using a wall forming material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as shown in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method using monomer polymerization, spray drying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling method seen in British Patent Nos. 952807 and 967074, etc. However, it is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Moreover, you may introduce | transduce into the microcapsule wall the compound which has crosslinkable functional groups, such as an ethylenically unsaturated bond which can be introduce | transduced into said water-insoluble polymer.

  The average particle size of the microcapsules is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is further more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

<Other photosensitive layer components>
The photosensitive layer of the present invention can further contain various additives as required. These will be described below.

<Surfactant>
In the present invention, it is preferable to use a surfactant in the photosensitive layer in order to promote developability and improve the coated surface state. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.

The nonionic surfactant used for this invention is not specifically limited, A conventionally well-known thing can be used. For example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol Fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N N- bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid ester, trialkylamine oxide, polyethylene glycol, copolymers of polyethylene glycol and polypropylene glycol.

  The anionic surfactant used in the present invention is not particularly limited, and conventionally known anionic surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinate esters, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy poly Oxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef oil, fatty acid alkyl esters Sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, polyoxyethylene alcohol Ruphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, styrene / maleic anhydride Examples thereof include partial saponification products of polymers, partial saponification products of olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.

The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.

  Of the above surfactants, the term “polyoxyethylene” can be read as “polyoxyalkylene” such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc. These surfactants can also be used.

  More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Also preferred are the fluorosurfactants described in JP-A-62-170950, JP-A-62-226143 and JP-A-60-168144.

Surfactant can be used individually or in combination of 2 or more types.
The content of the surfactant is preferably 0.001 to 10% by mass and more preferably 0.01 to 7% by mass with respect to the total solid content of the photosensitive layer.

<Hydrophilic polymer>
In the present invention, a hydrophilic polymer can be contained in order to improve the developability and the microcapsule dispersion stability.
Examples of the hydrophilic polymer include hydroxy group, carboxyl group, carboxylate group, hydroxyethyl group, polyoxyethyl group, hydroxypropyl group, polyoxypropyl group, amino group, aminoethyl group, aminopropyl group, ammonium group, Preferred examples include those having a hydrophilic group such as an amide group, carboxymethyl group, sulfonic acid group, and phosphoric acid group.

  Specific examples include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, Polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropyl methacrylate, homopolymers and copolymers of hydroxypropyl acrylate, homopolymers of hydroxybutyl methacrylate Polymers and copolymers, homopolymers and copolymers of hydroxybutyl acrylate Polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide homopolymers and copolymers having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more , Homopolymers and polymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide, polyvinylpyrrolidone, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, etc. Is mentioned.

The hydrophilic polymer preferably has a mass average molecular weight of 5000 or more, more preferably 10,000 to 300,000. The hydrophilic polymer may be any of a random polymer, a block polymer, a graft polymer, and the like.
The content of the hydrophilic polymer in the photosensitive layer is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the photosensitive layer.

<Colorant>
In the present invention, a dye having a large absorption in the visible light region can be used as an image colorant. 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 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc. And dyes described in Japanese Patent No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.

  These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The amount added is preferably 0.01 to 10% by mass with respect to the total solid content of the photosensitive layer.

<Bakeout agent>
In the photosensitive layer of the present invention, a compound that changes color by an acid or a radical can be added in order to form a printout image. As such a compound, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

  Specific examples include brilliant green, ethyl violet, methyl green, crystal violet, basic fuchsin, methyl violet 2B, quinaldine red, rose bengal, methanyl yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, Congo Fred, Benzopurpurin 4B, α-Naphthyl Red, Nile Blue 2B, Nile Blue A, Methyl Violet, Malachide Green, Parafuchsin, Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Kogyo Co., Ltd.], Oil Pink # 312 [Orient Chemical Co., Ltd.], Oil Red 5B [Orient Chemical Co., Ltd.], Oil Scarlet # 308 [Orient Gaku Kogyo Co., Ltd.], Oil Red OG [Orient Chemical Co., Ltd.], Oil Red RR [Orient Chemical Co., Ltd.], Oil Green # 502 [Orient Chemical Co., Ltd.], Spiron Red BEH Special [made by Hodogaya Chemical Co., Ltd.], m-cresol purple, cresol red, rhodamine B, rhodamine 6G, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p- Diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4-pN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4- - dyes and p of diethylamino phenyl imino-5-pyrazolone, p ', p "- hexamethyl triamnotriphenylmethane (leuco crystal violet), and a leuco dye such as Pergascript Blue SRB (manufactured by Ciba-Geigy).

  In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoylleucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.

  A suitable addition amount of the dye that changes color by acid or radical is 0.01 to 15% by mass relative to the solid content of the photosensitive layer.

<Polymerization inhibitor>
It is preferable to add a small amount of a thermal polymerization inhibitor to the photosensitive layer of the present invention in order to prevent unnecessary thermal polymerization of the polymerizable compound during the production or storage of the photosensitive layer.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t- (Butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the photosensitive layer.

<Higher fatty acid derivatives, etc.>
In order to prevent polymerization inhibition by oxygen, a higher fatty acid derivative such as behenic acid or behenamide is added to the photosensitive layer of the present invention so that it is unevenly distributed on the surface of the photosensitive layer during the drying process after coating. May be. The amount of the higher fatty acid derivative added is preferably from about 0.1 to about 10% by weight based on the total solid content of the photosensitive layer.

<Plasticizer>
The photosensitive layer of the present invention may contain a plasticizer. Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in. The plasticizer content is preferably about 30% by mass or less based on the total solid content of the photosensitive layer.

<Inorganic fine particles>
The photosensitive layer of the present invention may contain inorganic fine particles in order to improve the cured film strength of the image area. As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate or a mixture thereof can be preferably mentioned. Even if they are not photothermally convertible, they can be used for strengthening the film, enhancing interfacial adhesion by surface roughening, and the like. The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 to 3 μm. Within the above range, it is possible to form a non-image portion excellent in hydrophilicity that is stably dispersed in the photosensitive layer, sufficiently retains the film strength of the photosensitive layer, and does not easily cause stains during printing.
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total solid content of the photosensitive layer.

<Low molecular hydrophilic compound>
The photosensitive layer of the present invention can contain a hydrophilic low molecular weight compound for improving developability. Examples of the hydrophilic low-molecular compound include water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like, and ether or ester derivatives thereof, glycerin, Examples thereof include polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, and organic quaternary ammonium salts such as tetraethylamine hydrochloride.

<Formation of photosensitive layer>
The photosensitive layer of the present invention is formed by preparing or applying a coating solution by dispersing or dissolving the necessary components described above in a solvent. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like. However, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.
The photosensitive layer of the present invention can be formed by preparing a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents, and repeatedly applying and drying a plurality of times.

The coating, the photosensitive layer coating amount on the support obtained after drying (solid content) may be varied according to the intended purpose, generally 0.3 to 3.0 g / m ² is preferred. Within this range, good sensitivity and good film properties of the photosensitive layer can be obtained.
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

<Protective layer>
In the lithographic printing plate precursor according to the invention, a protective layer (oxygen blocking layer) is provided on the photosensitive layer in order to block the diffusion and penetration of oxygen that hinders the polymerization reaction during exposure. The protective layer used in the present invention preferably has an oxygen permeability A at 25 ° C. and 1 atm of 1.0 ≦ A ≦ 20 (mL / m ² · day). When the oxygen permeability A is extremely low at less than 1.0 (mL / m ² · day), unnecessary polymerization reaction occurs at the time of production and raw storage, and unnecessary fogging and image streaking occur during image exposure. The problem that fatness arises arises. Conversely, when the oxygen permeability A exceeds 20 (mL / m ² · day) and is too high, the sensitivity is lowered. The oxygen permeability A is more preferably in the range of 1.5 ≦ A ≦ 12 (mL / m ² · day), further preferably 2.0 ≦ A ≦ 10.0 (mL / m ² · day). In addition to the oxygen permeability described above, the properties desired for the protective layer further do not substantially inhibit the transmission of light used for exposure, have excellent adhesion to the photosensitive layer, and are easy in the development process after exposure. It is desirable that it can be removed. The device concerning such a protective layer has been conventionally made, and is described in detail in US Pat. No. 3,458,311 and JP-B-55-49729.

As a material that can be used for the protective layer, for example, a water-soluble polymer compound having relatively excellent crystallinity is preferably used. Specifically, polyvinyl alcohol, vinyl alcohol / vinyl phthalate copolymer, vinyl acetate / vinyl are used. Examples include water-soluble polymers such as alcohol / vinyl phthalate copolymer, vinyl acetate / crotonic acid copolymer, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, polyacrylic acid, and polyacrylamide. Or they can be mixed. Of these, the use of polyvinyl alcohol as the main component gives the best results in terms of basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol used for the protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains an unsubstituted vinyl alcohol unit for having necessary oxygen barrier properties and water solubility. Similarly, some of them may have other copolymer components. Specific examples of the polyvinyl alcohol include those having a hydrolysis degree of 71 to 100 mol% and a polymerization repeating unit in the range of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, L-8 and the like, and these can be used alone or in combination. In a preferred embodiment, the content of polyvinyl alcohol in the protective layer is 20 to 95% by mass, and more preferably 30 to 90% by mass.

  Moreover, well-known modified polyvinyl alcohol can also be used preferably. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxyl groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester modification of vinyl alcohol and various organic acids. Examples thereof include polyvinyl alcohol having various polymerization degrees having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, and the like.

  As a component used by mixing with polyvinyl alcohol, polyvinyl pyrrolidone or a modified product thereof is preferable from the viewpoint of oxygen barrier properties and development removability, and the content in the protective layer is 3.5 to 80% by mass, preferably 10 to 60%. It is 15 mass%, More preferably, it is 15-30 mass%.

  Components of the protective layer (selection of PVA, use of additives), coating amount, and the like are selected in consideration of fogging, adhesion, and scratch resistance in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of the PVA used (the higher the content of the unsubstituted vinyl alcohol unit in the protective layer), the thicker the film thickness, the higher the oxygen barrier property, which is advantageous in terms of sensitivity. The molecular weight of the (co) polymer such as polyvinyl alcohol (PVA) can be in the range of 2000 to 10 million, preferably in the range of 20,000 to 3 million.

  As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactant such as sodium acid salt; Amphoteric surfactant such as alkylaminocarboxylate and alkylaminodicarboxylate; Non-ionic surfactant such as polyoxyethylene alkylphenyl ether is several masses relative to polymer compound bin bar % Can be added.

In addition, adhesion to the image area and scratch resistance are extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on an oleophilic photosensitive layer, film peeling due to insufficient adhesion tends to occur, and the peeled part causes defects such as poor film hardening due to inhibition of oxygen polymerization. On the other hand, various proposals have been made to improve the adhesion between these two layers. For example, in U.S. Patent Application No. 292,501 and U.S. Patent Application No. 44,563, an acrylic emulsion or a water-insoluble vinyl pyrrolidone-vinyl acetate copolymer is contained in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesiveness can be obtained by mixing 20 to 60% by mass and laminating on a photosensitive layer. Any of these known techniques can be applied to the protective layer in the present invention. Such a coating method of the protective layer is described in detail in, for example, US Pat. No. 3,458,311 and JP-B-55-49729.

Furthermore, the protective layer in the lithographic printing plate precursor according to the invention preferably contains an inorganic stratiform compound for the purpose of improving oxygen barrier properties and photosensitive layer surface protection.
Here, the inorganic layered compound is a particle having a thin plate-like shape. For example, the following general formula A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂ [where A Is any of K, Na, and Ca, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.

In the mica group, examples of natural mica include muscovite, soda mica, phlogopite, biotite and sericite. Synthetic mica includes non-swellable mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 ( _{Si 4 O 10) F 2,} Na or Li teniolite _{(Na, Li) Mg 2 Li} (Si 4 O 10) F 2, montmorillonite based Na or Li hectorite _{(Na, Li) 1/8 Mg 2} /5 Li Examples thereof include swelling mica such as _1/8 (Si ₄ O ₁₀ ) F ₂ . Synthetic smectite is also useful.

In the present invention, among the inorganic layered compounds, fluorine-based swellable mica, which is a synthetic inorganic layered compound, is particularly useful. That is, this swellable synthetic mica and swellable viscosity minerals such as montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, Atomic substitution is significantly greater than other viscous minerals. As a result, the lattice layer is deficient in positive charges, and cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers in order to compensate for this. The cations present between these layers are called exchangeable cations and exchange with various cations. In particular, when the cation between the layers is Li ⁺ or Na ⁺ , the bond between the layered crystal lattices is weak because the ionic radius is small, and the layer swells greatly with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have this tendency and are useful in the present invention, and swellable synthetic mica is particularly preferably used.

  As the shape of the inorganic layered compound used in the present invention, from the viewpoint of diffusion control, the smaller the thickness, the better. The plane size is as long as it does not hinder the smoothness of the coated surface or the transmittance of actinic rays. Larger is better. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

As for the particle diameter of the inorganic stratiform compound used in the present invention, the average major axis is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

  When the inorganic layered compound particles having such a large aspect ratio are contained in the protective layer, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor does not deteriorate due to changes in humidity, and the storage stability is excellent.

  It is preferable that content of the inorganic stratiform compound in a protective layer is 5/1-1/100 by mass ratio with respect to the quantity of the binder used for a protective layer. Even when a plurality of types of inorganic layered compounds are used in combination, the total amount of these inorganic layered compounds is preferably the above-described mass ratio.

  Next, an example of a general dispersion method of the inorganic stratiform compound used for the protective layer will be described. First, 5 to 10 parts by mass of the swellable layered compound mentioned above as a preferred inorganic layered compound is added to 100 parts by mass of water, and the mixture is thoroughly swelled and swollen, and then dispersed by a disperser. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion of 5 to 10% by mass of the inorganic stratiform compound dispersed by the above method is highly viscous or gelled and has very good storage stability. When preparing a protective layer coating solution using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a binder solution.

  In addition to the inorganic layered compound, known additives such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film can be added to the protective layer coating solution. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, known additives for improving the adhesion to the photosensitive layer and the temporal stability of the coating solution may be added to the coating solution.

  The protective layer coating solution thus prepared is applied onto the photosensitive layer formed on the support and dried to form a protective layer. The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water. The method for applying the protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. . Specific examples of the protective layer include blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and bar coating.

The coating amount of the protective layer is preferably in the range of 0.05 to 10 g / m ^{2 in} terms of the coating amount after drying. When the inorganic layered compound is contained, 0.1 to 0.5 g / The range of m ² is more preferable, and when the inorganic layered compound is not contained, the range of 0.5 to 5 g / m ² is more preferable.

[Support]
The support used in the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like hydrophilic support. For example, paper, paper laminated with plastic (eg, 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.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. Preferable supports include a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of different elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. 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 preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.

  The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm, and even more preferably from 0.2 to 0.3 mm.

  Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it becomes easy to improve hydrophilicity and secure adhesion between the photosensitive layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like 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, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, 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.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

  The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

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, hydrochloric 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 conditions for anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, an electrolyte concentration of 1 to 80% by mass solution, a liquid temperature of 5 to 70 ° C., a current density of 5 to 60 A / d m ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is, but for further improvement in adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation and the like. If necessary, it contains a micropore enlargement treatment, a micropore sealing treatment, and a hydrophilic compound described in Japanese Patent Application Laid-Open Nos. 2001-253181 and 2001-322365. A surface hydrophilization treatment immersed in an aqueous solution can be selected as appropriate. Of course, these enlargement processing and sealing processing are not limited to those described above, and any conventionally known method can be performed.

Sealing treatment includes vapor sealing, single treatment with zirconic fluoride, treatment with an aqueous solution containing an inorganic fluorine compound such as treatment with sodium fluoride, vapor sealing with addition of lithium chloride, sealing with hot water. Hole processing is also possible.
Of these, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and sealing treatment with hot water are preferable.

  The hydrophilization treatment is described in the specifications of US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There are such alkali metal silicate methods. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in the specification of No. 272.

  When using a support having insufficient surface hydrophilicity, such as a polyester film, as the support of the present invention, it is desirable to apply a hydrophilic layer to make the surface hydrophilic. As the hydrophilic layer, at least one element selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and a transition metal described in JP-A-2001-199175 A hydrophilic layer formed by coating a coating solution containing a colloid of oxide or hydroxide, or organic hydrophilicity obtained by crosslinking or pseudo-crosslinking an organic hydrophilic polymer described in JP-A-2002-79772 A hydrophilic layer having a hydrophilic matrix, a hydrophilic layer having an inorganic hydrophilic matrix obtained by sol-gel conversion comprising hydrolysis, condensation reaction of polyalkoxysilane, titanate, zirconate or aluminate, or a metal oxide A hydrophilic layer made of an inorganic thin film having a surface is preferred. Arbitrariness. Among these, a hydrophilic layer formed by applying a coating solution containing a silicon oxide or a hydroxide colloid is preferable.

  Moreover, when using a polyester film etc. as a support body of this invention, it is preferable to provide an antistatic layer in the hydrophilic layer side of a support body, the opposite side, or both sides. In the case where the antistatic layer is provided between the support and the hydrophilic layer, it also contributes to improving the adhesion with the hydrophilic layer. As the antistatic layer, a polymer layer in which metal oxide fine particles or a matting agent are dispersed as described in JP-A-2002-79772 can be used.

In the case of an aluminum plate, for example, the support preferably has a center line average roughness of the surface of 0.10 to 1.2 μm. Within this range, good adhesion to the photosensitive layer, good printing durability and good stain resistance can be obtained.
The color density of the support is preferably 0.15 to 0.65 as the reflection density value. Within this range, good image formability by preventing halation during image exposure and good plate inspection after development can be obtained.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, it is preferable to provide an undercoat layer of a compound containing a polymerizable group on a support. When an undercoat layer is used, the photosensitive layer is provided on the undercoat layer. The undercoat layer reinforces the adhesion between the support and the photosensitive layer in the exposed area, and easily peels the photosensitive layer from the support in the unexposed area, thereby improving the developability.
As the undercoat layer, specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of description are mentioned suitably. Particularly preferred compounds include compounds having a polymerizable group such as a methacryl group and an allyl group and a support-adsorptive group such as a sulfonic acid group, a phosphoric acid group and a phosphoric acid ester. A compound having a hydrophilicity-imparting group such as an ethylene oxide group in addition to the polymerizable group and the support-adsorbing group can also be exemplified as a suitable compound.
The coating amount (solid content) of the undercoat layer is preferably from 0.1-100 mg / m ^2, and more preferably 1 to 30 mg / m ^2.

[Back coat layer]
After the surface treatment is performed on the support or after the undercoat layer is formed, a back coat can be provided on the back surface of the support, if necessary.
Examples of the back coat include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organometallic compounds or inorganic metal compounds described in JP-A-6-35174. A coating layer made of a metal oxide obtained in this manner is preferred. Among them, it is inexpensive to use a silicon alkoxy compound such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4. It is preferable in terms of easy availability.

[Plate making method]
After the lithographic printing plate precursor in the present invention is image-exposed with a light source of 350 nm to 450 nm, the protective layer is rubbed with a rubbing member in the presence of a developer having a pH of 2 to 10 with an automatic processor, for example. In addition, the photosensitive layer in the non-exposed area can be removed at once to form an image on the surface of the aluminum plate support.
That is, after removing the protective layer and the non-exposed portion of the photosensitive layer at once, it can be set on a printing machine and printed immediately.
In addition, such processing in an automatic developing machine has an advantage that it is free from dealing with the development residue derived from the protective layer / photosensitive layer that occurs in the case of on-press development.

The developer used in the present invention is an aqueous solution having a pH of 2 to 10. For example, water alone or an aqueous solution containing water as a main component (containing 60% by mass or more of water) is preferable. In particular, an aqueous solution having the same composition as that of a generally known fountain solution, a surfactant (anionic, nonionic, An aqueous solution containing a cationic system or the like, or an aqueous solution containing a water-soluble polymer compound is preferable. In particular, an aqueous solution containing both a surfactant and a water-soluble polymer compound is preferable. The pH of the developer is more preferably 3-8, still more preferably 4-7.
When an acidic to neutral developer is used, it is preferable to contain either an organic acid or an inorganic acid. By containing an organic acid or an inorganic acid, developability can be improved during plate making, and it is possible to suppress the occurrence of stains in the non-image area of the plate that has been made.

Examples of the anionic surfactant used in the developer of the present invention include fatty acid salts, abietic acid salts, hydroxyalkane sulfonic acid salts, alkane sulfonic acid salts, dialkyl sulfosuccinic acid salts, linear alkyl benzene sulfonic acid salts, and branched alkyl benzene sulfonic acid. Acid salts, alkylnaphthalene sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamide disodium salts, petroleum Sulfonates, sulfated castor oil, sulfated beef tallow oil, sulfate esters of fatty acid alkyl esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfate esters, Fatty acid monoglyceride sulfates, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates , Partially saponified products of styrene-maleic anhydride copolymer, partially saponified products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensate and the like. Among these, dialkyl sulfosuccinates, alkyl sulfate esters and alkyl naphthalene sulfonates are particularly preferably used.

  The cationic surfactant used in the developer of the present invention is not particularly limited, and conventionally known ones can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

Nonionic surfactants used in the developer of the present invention include polyethylene glycol type higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, higher Alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, oil and fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, etc. , Fatty acid ester of glycerol of polyhydric alcohol type, fatty acid ester of pentaerythritol, sorbitol and Fatty acid esters of Rubitan, fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, fatty acid amides of alkanolamines.
These nonionic surfactants may be used alone or in admixture of two or more. In the present invention, ethylene oxide adduct of sorbitol and / or sorbitan fatty acid ester, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, polyhydric alcohol Fatty acid esters are more preferred.

Further, from the viewpoint of stable solubility or turbidity in water, the nonionic surfactant used in the developer of the present invention is HLB (Hydrophile-Lipophile).
The (Balance) value is preferably 6 or more, and more preferably 8 or more. Furthermore, the ratio of the nonionic surfactant contained in the developer is preferably 0.01 to 10% by mass, and more preferably 0.01 to 5% by mass.
Also, acetylene glycol-based and acetylene alcohol-based oxyethylene adducts, fluorine-based and silicon-based surfactants can be used in the same manner.
As the surfactant used in the developer of the present invention, a nonionic surfactant is particularly suitable from the viewpoint of foam suppression.

Examples of the water-soluble polymer compound used in the developer of the present invention include soybean polysaccharide, modified starch, gum arabic, dextrin, fibrin derivatives (eg, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.) and modified products thereof, pullulan. , Polyvinyl alcohol and its derivatives, polyvinyl pyrrolidone, polyacrylamide and acrylamide copolymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, styrene / maleic anhydride copolymer, etc. It is done.

  A well-known thing can be used for the said soybean polysaccharide, for example, there exists a brand name Soya Five (made by Fuji Oil Co., Ltd.) as a commercial item, and the thing of various grades can be used. What can be preferably used is one in which the viscosity of a 10% by mass aqueous solution is in the range of 10 to 100 mPa / sec.

  As the modified starch, known ones can be used, and starch such as corn, potato, tapioca, rice and wheat is decomposed with acid or enzyme in the range of 5 to 30 glucose residues per molecule, and further in an alkali. It can be made by a method of adding oxypropylene or the like.

  Two or more water-soluble polymer compounds can be used in combination. The content of the water-soluble polymer compound in the developer is preferably from 0.1 to 20% by mass, and more preferably from 0.5 to 10% by mass.

  Further, the developer of the present invention may contain an organic solvent. Examples of the organic solvent that can be contained include aliphatic hydrocarbons (hexane, heptane, “Isopar E, H, G” (manufactured by Esso Chemical Co., Ltd.) or gasoline, kerosene, etc.), and aromatic hydrocarbons (toluene). , Xylene, etc.), halogenated hydrocarbons (methylene dichloride, ethylene dichloride, tricrene, monochlorobenzene, etc.) and polar solvents.

  Polar solvents include alcohols (methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol monomethyl ether, 2-ethoxyethanol, diethylene glycol monoethyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, propylene glycol monoethyl ether , Propylene glycol monomethyl ether, polyethylene glycol monomethyl ether, polypropylene glycol, tetraethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, methylphenyl carbinol, n-amyl alcohol, methyl amyl alcohol, etc.) , (Acetone, methyl ethyl ketone, ethyl butyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), esters (ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, methyl lactate, butyl lactate, ethylene glycol monobutyl acetate, propylene Glycol monomethyl ether acetate, diethylene glycol acetate, diethyl phthalate, butyl levulinate, etc.) and others (triethyl phosphate, tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, etc.).

  If the organic solvent is insoluble in water, it can be used after being solubilized in water using a surfactant or the like. If the developer contains an organic solvent, safety, ignition, From the viewpoint of property, the concentration of the solvent is preferably less than 40% by mass.

  In addition to the above, the developer of the present invention may contain a preservative, a chelate compound, an antifoaming agent, an organic acid, an inorganic acid, an inorganic salt, and the like.

Preservatives include phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzisothiazolin-3-one, benztriazole derivatives, amiding anidine derivatives, quaternary ammonium salts, pyridine, Derivatives such as quinoline and guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3diol, 1,1-dibromo-1-nitro-2-ethanol, 1,1-dibromo-1-nitro-2-propanol and the like can be preferably used.

  Examples of the chelate compound include ethylenediaminetetraacetic acid, potassium salt thereof, sodium salt thereof; diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof; triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof, hydroxyethylethylenediaminetriacetic acid Nitrilotriacetic acid, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri (methylenephosphonic acid), potassium salt, sodium salt And organic phosphonic acids and phosphonoalkanetricarboxylic acids. Organic amine salts are also effective in place of the sodium and potassium salts of the chelating agents.

As the antifoaming agent, a general silicon-based self-emulsifying type, emulsifying type, or nonionic surfactant having a HLB of 5 or less can be used. Silicon antifoaming agents are preferred.
Among them, emulsification dispersion type and solubilization can be used.

  Examples of organic acids include citric acid, acetic acid, succinic acid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malic acid, lactic acid, levulinic acid, p-toluenesulfonic acid, xylenesulfonic acid, phytic acid, and organic phosphonic acid. . The organic acid can also be used in the form of its alkali metal salt or ammonium salt.

  Examples of inorganic acids and inorganic salts include phosphoric acid, metaphosphoric acid, primary ammonium phosphate, secondary ammonium phosphate, primary sodium phosphate, secondary sodium phosphate, primary potassium phosphate, secondary potassium phosphate, Examples include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogen sulfate, nickel sulfate and the like.

  The developer described above can be used as a developer and developer replenisher for the exposed negative lithographic printing plate precursor, and is preferably applied to an automatic processor described later. When developing using an automatic processor, the developing solution becomes fatigued according to the amount of processing, so the processing capability may be restored using a replenisher or a fresh developer. This replenishing method is also preferably applied to the lithographic printing plate making method of the present invention.

  The development treatment with an aqueous solution having a pH of 2 to 10 in the present invention can be preferably carried out by an automatic processor equipped with a developer supply means and a rubbing member. As an automatic processor, for example, an automatic processor described in JP-A-2-220061 and JP-A-60-59351, which performs a rubbing process while transporting a lithographic printing plate precursor after image recording, or a cylinder Examples thereof include an automatic processor described in US Pat. Nos. 5,148,746, 5,568,768 and British Patent 2,297,719, which rub the lithographic printing plate precursor after image recording set thereon while rotating a cylinder. Among these, an automatic processor using a rotating brush roll as the rubbing member is particularly preferable.

The rotating brush roll that can be preferably used in the present invention can be appropriately selected in consideration of the difficulty of scratching the image area and the stiffness of the support of the lithographic printing plate precursor. As the rotating brush roll, a known one formed by planting a brush material on a plastic or metal roll can be used. For example, as described in Japanese Patent Application Laid-Open No. 58-159533, Japanese Patent Application Laid-Open No. 3-100554, or Japanese Utility Model Publication No. 62-167253, metal or plastic in which brush materials are implanted in rows. A brush roll can be used in which the groove mold material is radially wound around a plastic or metal roll as a core without a gap.
The brush material includes plastic fibers (for example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6.6 and nylon 6.10, polyacrylonitrile, poly (meth) acrylate, etc. Acrylic and polyolefin synthetic fibers such as polypropylene and polystyrene) can be used. For example, the fiber has a hair diameter of 20 to 400 μm and a hair length of 5 to 30 mm. Can be used.
Furthermore, the outer diameter of the rotating brush roll is preferably 30 to 200 mm, and the peripheral speed at the tip of the brush rubbing the plate surface is preferably 0.1 to 5 m / sec.
Moreover, it is preferable to use two or more rotating brush rolls.

  The rotating direction of the rotating brush roll used in the present invention may be the same or opposite to the transport direction of the planographic printing plate precursor of the present invention. For example, the automatic processing illustrated in FIG. When using two or more rotating brush rolls as in the machine, it is preferable that at least one rotating brush roll rotates in the same direction and at least one rotating brush roll rotates in the opposite direction. . This further ensures the removal of the heat sensitive layer in the non-image area. Furthermore, it is also effective to swing the rotating brush roll in the direction of the rotation axis of the brush roll.

  Although the temperature of the developer can be used at any temperature, it is preferably 10 ° C to 50 ° C.

  In the present invention, the lithographic printing plate after the rubbing treatment can be optionally washed with water, dried and desensitized. In the desensitizing treatment, a known desensitizing solution can be used.

  In addition, as the plate-making process of the lithographic printing plate from the lithographic printing plate precursor according to the present invention, the entire surface may be heated before exposure, during exposure, and between exposure and development, if necessary. By such heating, the image forming reaction in the photosensitive layer is promoted, and advantages such as improvement in sensitivity and printing durability and stabilization of sensitivity may occur. Further, for the purpose of improving the image strength and printing durability, it is also effective to subject the developed image to full post heating or full exposure. Usually, the heating before development is preferably performed under a mild condition of 150 ° C. or less. If the temperature is too high, problems such as covering up to the non-image area occur. Very strong conditions are used for heating after development. Usually, it is the range of 200-500 degreeC. If the temperature is low, sufficient image strengthening action cannot be obtained. If the temperature is too high, problems such as deterioration of the support and thermal decomposition of the image area occur.

  Prior to the above development processing, the lithographic printing plate precursor is imagewise exposed with a laser having a wavelength of 350 to 450 nm.

As available laser light sources of 350 nm to 450 nm, the following can be used.
As a gas laser, an Ar ion laser (364 nm, 351 nm, 10 mW to 1 W), a Kr ion laser (356 nm, 351 nm, 10 mW to 1 W), a He—Cd laser (441 nm, 325 nm, 1 mW to 100 mW), and a solid laser as Nd: YAG (YVO ₄ ) and SHG crystal × 2 combinations (355 nm, 5 mW to 1 W), Cr: LiSAF and SHG crystal combination (430 nm, 10 mW), as a semiconductor laser system, KNbO ₃ ring resonator (430 nm, 30 mW), Combination of waveguide type wavelength conversion element and AlGaAs / InGaAs semiconductor (380 nm to 450 nm, 5 mW to 100 mW), combination of waveguide type wavelength conversion element and AlGaInP, AlGaAs semiconductor (300 nm to 350 nm, 5 mW to 100 mW) ), AlGaInN (350 nm to 450 nm, 5 mW to 30 mW), N ₂ laser (337 nm, pulse 0.1 to 10 mJ), XeF (351 nm, pulse 10 to 250 mJ) as a pulse laser. In particular, an AlGaInN semiconductor laser (commercially available InGaN-based semiconductor laser 400 to 410 nm, 5 to 30 mW) is preferable in terms of wavelength characteristics and cost.

Further, as the lithographic printing plate precursor exposure apparatus of the scanning exposure method, there are an inner drum method, an outer drum method, and a flat bed method as an exposure mechanism, and a light source that can continuously oscillate among the light sources is preferably used. it can. Practically, the following exposure apparatus is particularly preferable because of the relationship between the sensitivity of the lithographic printing plate precursor and the plate making time.
・ Single beam to triple beam exposure equipment that uses one or more gas lasers or solid-state laser light sources so that it becomes a semiconductor laser with a total output of 20 mW or more with an internal drum system. ・ A total output of 20 mW or more with a flat bed system. Multi-beam (1 to 10) exposure equipment that uses one or more semiconductor lasers, gas lasers, or solid-state lasers • Use one or more semiconductor lasers, gas lasers, or solid-state lasers to achieve a total output of 20 mW or more with the external drum system Multi-beam (1 to 9) exposure apparatus ・ Multi-beam (10 or more) exposure apparatus using one or more semiconductor lasers or solid-state lasers so that the total output is 20 mW or more by the external drum method In general, laser-sensitive lithographic printing plate precursors (photosensitive materials) Degrees X (J / cm ^2), the exposure area S (cm ²⁾ of photosensitive material, wherein between the laser light source 1 power q (W), the laser number n, the total exposure time t (s) (eq 1 ) Holds.

  X · S = n · q · t (eq 1)

i) In the case of the internal drum (single beam) system, the laser rotation speed f (radians / s), the sub-scanning length Lx (cm) of the photosensitive material, the resolution Z (dots / cm), and the total exposure time t (s) In general, equation (eq 2) holds.

  f · Z · t = Lx (eq 2)

ii) External drum (multi-beam) system Drum rotation speed F (radians / s), photosensitive material sub-scanning length Lx (cm), resolution Z (dots / cm), total exposure time t (s), number of beams In general, formula (eq 3) is established during (n).

  F.Z.n.t = Lx (eq 3)

iii) Flat head (multi-beam) system Polygon mirror rotation speed H (radians / s), photosensitive material sub-scanning length Lx (cm), resolution Z (dots / cm), total exposure time t (s), Equation (eq 4) is generally established between the number of beams (n).

  F.Z.n.t = Lx (eq 4)

Resolution (2560 dpi) required for the actual printing plate, plate size (A1 / B1, sub-scan length 42 inch), exposure conditions of about 20 sheets / hour and photosensitive characteristics of the planographic printing plate precursor of the present invention (photosensitive wavelength, By substituting (sensitivity: about 0.1 mJ / cm ² ) into the above formula, it is understood that a combination with a multi-beam exposure method using a laser having a total output of 20 mW or more is particularly preferable in the planographic printing plate precursor of the present invention. it can. Further, by combining operability, cost, etc., a combination with an external drum type semiconductor laser multi-beam (10 or more) exposure apparatus is most preferable.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

[Examples 1 to 18 and Comparative Examples 1 to 10]
[Preparation of lithographic printing plate precursor]
(Production of support)
In order to remove rolling oil on the surface of an aluminum plate (material 1050) having a thickness of 0.3 mm, a degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution. The aluminum surface was grained using three bundle-planted nylon brushes and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed thoroughly with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in a 20 mass% nitric acid aqueous solution at 60 ° C for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .

Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Next, nitric acid electrolysis was performed with an aqueous solution of 0.5% by mass hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was the anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying. The plate was provided with a DC anodized film of 2.5 g / m ² at a current density of 15 A / dm ² using a 15% by mass sulfuric acid aqueous solution (containing 0.5% by mass of aluminum ions) as an electrolyte, then washed with water and dried. .
The centerline average roughness Ra (JIS B0601) of the surface of the support thus obtained was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

Further, the following undercoat liquid (1) was bar-coated and then oven-dried at 80 ° C. for 10 seconds to prepare a support having an undercoat layer having a dry coating amount of 10 mg / m ² .

<Undercoat liquid (1)>
・ Undercoat compound (1) below 0.017 g
・ Methanol 9.00 g
・ Water 1.00g

(Preparation of lithographic printing plate precursor (1))
A photosensitive layer coating solution (1) having the following composition was bar coated on the support provided with the undercoat layer, followed by oven drying at 70 ° C. for 60 seconds, and a photosensitive layer having a dry coating amount of 1.1 g / m ² . On this, a protective layer coating solution (1) having the following composition was applied to a bar so that the dry coating amount was 0.75 g / m ^2, and then dried at 125 ° C. for 70 seconds to obtain the sample of Example 1. A lithographic printing plate precursor (1) was obtained.

<Photosensitive layer coating solution (1)>
(Starting system: listed in Table-1)
・ Initiator compound 0.2g
・ Sensitizing dye 0.1g
・ Co-sensitizer 0.3g
(Polymerization system)
・ Binder polymer (described in Table-1) 3.0g
-Polymerizable compound 6.2g
Isocyanuric acid EO-modified diacrylate (Aronix M-215, manufactured by Toagosei Co., Ltd.)
・ Royco Crystal Violet 0.2g
・ 0.1 g of the following fluorosurfactant (1)

・ The following microcapsule dispersion 25.0 g
・ Methyl ethyl ketone 35.0g
・ 3-methoxy-2-propanol 35.0 g

(Preparation of microcapsule dispersion)
As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, isocyanuric acid EO-modified diacrylate (Toa Gosei Co., Ltd. Aronix M-215) 4.15 g and 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) were dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 3 hours. The microcapsule liquid thus obtained was diluted with distilled water to a solid content concentration of 20% by mass to obtain a microcapsule dispersion. The average particle size was 0.25 μm.
<Protective layer coating solution (1)>
・ The following mica dispersion 13.0g
Polyvinyl alcohol (saponification degree 98 mol%, polymerization degree 500) 1.3 g
-Sodium 2-ethylhexyl sulfosuccinate 0.2g
・ Poly (vinyl pyrrolidone / vinyl acetate (1/1)) (molecular weight 70,000) 0.05g
・ Surfactant (Emalex 710, manufactured by Nippon Emulsion Co., Ltd.) 0.05g
・ 133g of water

(Preparation of mica dispersion)
To 368 g of water, 32 g of synthetic mica (“Somasif ME-100”: manufactured by Corp Chemical Co., aspect ratio: 1000 or more) was added and dispersed using an homogenizer until the average particle size (laser scattering method) became 0.5 μm. A mica dispersion was obtained.

(Preparation of lithographic printing plate precursors (2) to (18) and comparative lithographic printing plate precursors (1) to (10))
The lithographic printing plate precursors of Examples (2) to (18) are the same as Example 1 except that the sensitizing dye, initiator compound, co-sensitizer and binder polymer are each changed to the compounds shown in Table 1. Comparative lithographic printing plate precursors (1) to (10) for (2) to (18) and Comparative Examples (1) to (10) were prepared.

[Evaluation of planographic printing plate precursor]
Using the lithographic printing plate precursors (1) to (18) and the comparative lithographic printing plate precursors (1) to (10), exposure and development are carried out as follows, and sensitivity, storage stability, in yellow light work The fog was evaluated.

(Sensitivity evaluation)
A Fuji step guide manufactured by Fuji Photo Film Co., Ltd. (grayscale whose transmission optical density changes discontinuously at △ D = 0.15) is brought into close contact with the lithographic printing plate precursor, using a xenon lamp as a light source, and a short wave semiconductor. For the purpose of estimating the suitability for exposure to laser, Kenko BP-40 was used as an optical filter, and exposure was performed with monochromatic light of 400 nm so as to be 90 μJ / cm ² .

The exposed lithographic printing plate precursor was developed with an automatic developing processor having a structure shown in FIG. 1 using a developer (pH: 4.5) having the following composition. The automatic processor has two rotating brush rolls, and the first rotating brush roll with which the lithographic printing plate precursor first comes in contact is made of polybutylene terephthalate fibers (hair diameter 200 μm, hair length 17 mm). The brush roll with an outer diameter of 90 mm implanted was rotated 200 times per minute in the same direction as the conveying direction (peripheral speed of the brush tip: 0.94 m / sec), and the second rotating brush roll was made of polybutylene terephthalate fiber ( A brush roll having an outer diameter of 60 mm in which hair diameter of 200 μm and hair length of 17 mm was implanted was rotated 200 times per minute in the direction opposite to the conveying direction (peripheral speed of the brush tip of 0.63 m / sec). The conveyance speed of the lithographic printing plate precursor was 100 cm / min.
The developer was showered from the spray pipe with a circulation pump and supplied to the plate surface. The tank capacity of the developer was 10 liters.

Developer ・ Water 100g
・ Benzyl alcohol 1g
・ Polyoxyethylene naphthyl ether 1g
(Average number of oxyethylene n = 13)
・ Dioctyl sulfosuccinate sodium salt 0.5g
・ 1g gum arabic
・ Ethylene glycol 0.5g
・ Primary ammonium phosphate 0.05g
・ Citric acid 0.05g
・ Ethylenediaminetetraacetate tetrasodium salt 0.05g

In the obtained lithographic printing plate, the maximum number of steps of the gray scale from which the image was completely removed was read, the exposure energy amount was determined, and the clear sensitivity (μJ / cm ² ) was calculated. The smaller the exposure energy amount, the higher the sensitivity. The results are shown in Table 1.

(Evaluation of storage stability)
The lithographic printing plate precursor was exposed immediately after production (Condition i) and stored under forced conditions at 60 ° C. for 10 days (Condition ii), and then exposed and developed in the same manner as in the above sensitivity evaluation, and each clear sensitivity was determined. The difference between the clear sensitivity of condition i and the clear sensitivity of condition ii was defined as the clear sensitivity ratio (condition ii / condition i). The closer this value is to 1, the smaller the change in image formation sensitivity between the lithographic printing plate precursor without aging and the lithographic printing plate precursor after forced aging, and it can be said that the storage stability is high. The results are shown in Table 1.

(Evaluation of fog in yellow light work)
In order to evaluate the safelight suitability, the obtained lithographic printing plate precursor was exposed to yellow light (cut at a wavelength of 500 nm or less) for 30 minutes before exposure, and then as an exposure apparatus, a violet semiconductor laser setter Vx9600 manufactured by FUJIFILM Electronic Imaging Ltd. (InGaN semiconductor laser 405 nm ± 10 nm emission / output 30 mW), an exposure amount of 90 μJ / cm ² and a resolution of 2438 dpi was used to draw a 35% flat net on an FM screen TAFFETA20 manufactured by Fuji Photo Film. Thereafter, development processing was performed according to the development step in the sensitivity evaluation. By visual confirmation, lithographic printing plate precursors with fog (no safelight suitability) were evaluated as x, and lithographic printing plate precursors with no fogging (safelight suitability) were shown as ◯, and fogging was evaluated during yellow light work. It was. The results are shown in Table 1.

  The sensitizing dyes according to the present invention used in the starting system in Table 1 are all shown as the exemplified compounds. The structures of the initiators T-1 to T-6, the co-sensitizers R-1 and R-2, and the binder polymers P-1 to P-5 are as shown below. The following sensitizing dyes H-1 to H-3 used in the comparative examples are dye compounds outside the scope of the present invention.

As can be seen from Table 1, according to the method of preparing a lithographic printing plate of the present invention, it is possible to make a plate under a yellow light while maintaining high sensitivity. Specifically, it can be seen that the planographic printing plate precursor of the present invention is excellent in sensitivity, storage stability, and safelight suitability as is apparent from, for example, a comparison between Example 1 and Comparative Example 3. Further, as is clear from comparison between Example 1 and Example 5 or 7, in the sensitizing dye represented by the general formula (III), X ₂ is dimethyl carbon, which has particularly excellent storage stability. You can see that
Further, when a binder polymer having a large acid value (2.06 meq / g) is used as in Comparative Examples 8 to 10, development failure occurs and image formation becomes impossible. As described above, it is important that the binder polymer in the photosensitive layer of the lithographic printing plate precursor according to the present invention has a low acid value.

Structure of automatic processor

Explanation of symbols

1: rotating brush roll 2: receiving roll 3: transport roll 4: transport guide plate 5: spray pipe 6: pipeline 7: filter 8: plate feed table 9: plate discharge table 10: developer tank 11: circulation pump 12: flat plate Print version

Claims (4)

On the hydrophilic support, (A) a sensitizing dye represented by the following general formula (I), (B) an initiator compound, (C) a polymerizable compound, and (D) an acid value of 0.3 meq / g. After exposing a lithographic printing plate precursor having a photosensitive layer containing the following hydrophobic binder polymer and a protective layer in this order with a laser having a wavelength of 350 to 450 nm, the pH is adjusted by an automatic processor equipped with a rubbing member. A method for preparing a lithographic printing plate, comprising removing a protective layer and a photosensitive layer in a non-exposed portion by rubbing the plate surface with a rubbing member in the presence of 2 to 10 developer.

(In the general formula (I), X ₁ and X ₂ each independently represents an oxygen atom, a sulfur atom, —CR ₁₁ R ₁₂ — or —NR ₁₃ —, wherein at least one of them represents an oxygen atom, a sulfur atom or -NR ₁₃ -. a it .Y represents an oxygen atom, a sulfur atom or = NR ₁₄ .R _{1 ~R 14} each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, or R ₁ to R ₁₄ is They may be bonded to each other to form an aliphatic or aromatic ring.)   (D) The hydrophobic binder polymer having an acid value of 0.3 meq / g or less is at least one selected from a (meth) acrylic copolymer having a crosslinkable group in the side chain and a polyurethane resin having a crosslinkable group in the side chain. The method for preparing a lithographic printing plate according to claim 1, wherein the method is a seed.   (B) The method for preparing a lithographic printing plate according to claim 1, wherein the initiator compound is a hexaarylbiimidazole compound.   A lithographic printing plate produced by the method for producing a lithographic printing plate according to any one of claims 1 to 3.

Images