JP2011213113A - Original plate for lithographic printing plate and method for plate making - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original plate for a lithographic printing plate which enables image recording by using infrared laser beam, has high print resistance and good stain resistance, and enables development process with alkali developer or on-press development.SOLUTION: The original plate for lithographic printing plate has on its hydrophilic support body an image recording layer including a polymerizable composition which contains a combination of polymer particles (A), a radical polymerizable compound (B), and an infrared absorbing dye (C). Characteristically, the polymer particles (A) are polymer particles linked by covalent binding of a polymerization initiator group consisting of a sulfonium salt, an iodonium salt, a diazonium salt, an azinium salt, an oxime compound, and a triazine compound, and of at least one compound selected from auxiliary agents of a specific structure.

Description

  The present invention relates to a so-called direct plate-making lithographic printing plate precursor that can be directly made from various digital signals from a computer or the like, particularly a lithographic printing plate precursor having improved printing durability, stain resistance, and storage stability, and its It relates to the plate making method.

  Solid lasers, semiconductor lasers, and gas lasers that emit ultraviolet light, visible light, and infrared light having a wavelength of 300 nm to 1200 nm are easily available in high output and small size. It is very useful as a recording light source when making a plate directly from digital data. Various studies have been conducted on recording materials that are sensitive to these various laser beams. In particular, when a material that can be recorded with an infrared laser having a photosensitive wavelength of 760 nm or more is used, there is an advantage that handling in a bright room becomes easy. As a representative example, for example, radical polymerization described in Patent Document 1 Type negative recording material.

In addition, in a conventional lithographic printing plate precursor (hereinafter also referred to as PS plate), after exposure, a step (development processing) for dissolving and removing the non-image part is indispensable, and the developed printing plate is washed with water, A post-treatment step is also necessary, in which treatment is performed with a rinse solution containing a surfactant or treatment with a desensitizing solution containing gum arabic or a starch derivative. The point that these additional wet treatments are indispensable is a big problem for the conventional PS plate. Even if the first half (image forming process) of the plate making process is simplified by the digital processing, the effect of the simplification is insufficient in the wet process where the second half (development process) is complicated.
Particularly in recent years, consideration for the global environment has become a major concern for the entire industry. In consideration of the environment, processing with a developing solution closer to the neutral range and a small amount of waste liquid are cited as problems. Furthermore, it is desirable to simplify the wet post-treatment or change to a dry treatment.

  From this point of view, one method of eliminating the processing step is to mount the exposed printing original plate on the cylinder of the printing press, and supply dampening water and ink while rotating the cylinder to remove the non-printing original plate. There is a method called on-machine development that removes the image area. That is, after the printing original is exposed, it is mounted on a printing machine as it is, and the developing process is completed in a normal printing process.

In order to satisfy the requirements for on-press development, a lithographic printing plate precursor in which an image recording layer in which thermoplastic hydrophobic polymer fine particles are dispersed in a hydrophilic binder polymer is provided on a hydrophilic support has been proposed ( For example, see Patent Document 2). In making the plate, it is exposed with an infrared laser, and the thermoplastic hydrophobic polymer fine particles are coalesced (fused) with heat generated by photothermal conversion to form an image. On-press development can be performed by supplying at least one of water and ink. This lithographic printing plate precursor also has handleability in a bright room because the photosensitive region is an infrared region.
However, an image formed by coalescence (fusion) of thermoplastic hydrophobic polymer fine particles has insufficient strength and has a problem in printing durability as a printing plate.

Further, a lithographic printing plate precursor including microcapsules encapsulating a polymerizable compound in place of the thermoplastic fine particles has been proposed (see, for example, Patent Documents 3 to 8). The original plate according to such a proposal has an advantage that the polymer image formed by the reaction of the polymerizable compound is superior in strength to the image formed by fusing fine particles.
In addition, since the polymerizable compound has high reactivity, many methods for isolating it using microcapsules have been proposed. It has been proposed to use a thermally decomposable polymer for the shell of the microcapsule.

  However, the conventional lithographic printing plate precursors described in Patent Documents 1 to 8 above do not have sufficient printing durability of images formed by laser exposure, and further improvements are required. That is, it is difficult to obtain sufficient printing durability in an image cured with a material that can be recorded with an infrared laser having a photosensitive wavelength of 760 nm or more. If a support having a surface with low hydrophilicity is used in order to improve printing durability, ink will also adhere to non-image areas during printing, resulting in printing stains. As described above, in the case of a material that can be recorded with an infrared laser having a photosensitive wavelength of 760 nm or more, there is a problem that the stain resistance is good and sufficient printing durability is provided. In particular, in the on-press development using fountain solution and / or printing ink, the developability is inferior to that of a system developing with an alkaline developer, and therefore, it is easily contaminated and becomes a more difficult problem.

JP 2004-212558 A Japanese Patent No. 2938397 JP 2000-2111262 A JP 2001-277740 A JP 2002-29162 A JP 2002-46361 A JP 2002-137562 A JP 2002-326470 A

  An object of the present invention is a lithographic printing plate precursor that can be directly made from digital data such as a computer by recording using a solid-state laser or semiconductor laser beam that emits infrared light. An object of the present invention is to provide a lithographic printing plate precursor having good storage stability. Another object of the present invention is to provide an on-press developable lithographic printing plate precursor having high printing durability, stain resistance and storage stability, and a plate making method thereof.

1. A lithographic printing plate precursor having a polymerizable composition containing a combination of (A) fine polymer particles, (B) a radical polymerizable compound, and (C) an infrared absorbing dye on a hydrophilic support in an image recording layer. (A) The polymer fine particles are at least one selected from a polymerization initiator group consisting of a sulfonium salt, an iodonium salt, a diazonium salt, an azinium salt, an oxime compound and a triazine compound, and a compound represented by the following general formula (1). A lithographic printing plate precursor comprising fine polymer particles covalently linked to a compound.

In general formula (1), A represents an aromatic hydrocarbon group or a heterocyclic group. X ¹ represents a divalent linking group selected from —O—, —S—, and —N (R ³ ) —. R ³ represents a hydrogen atom or an alkyl group which may have a substituent. R ¹ and R ² each independently represents a hydrogen atom or an alkyl group.

2. The polymer fine particles are represented by a polymerization initiator group having a polyvalent isocyanate compound, a sulfonium salt, an iodonium salt, a diazonium salt, an azinium salt, an oxime compound and a triazine compound having a hydroxy group or an amino group, and the general formula (1). 2. The lithographic printing plate precursor as described in 1 above, which is polymer fine particles obtained by addition reaction with at least one selected from the following compounds.
3. 2. The lithographic printing plate precursor as described in 1 above, wherein the polymer fine particles are polymer fine particles obtained by radical polymerization of a compound represented by the general formula (1) having a radical polymerizable group.
4). 4. The lithographic printing plate precursor as described in any one of 1 to 3 above, wherein the infrared absorbing dye is a cyanine dye represented by the following general formula (2).

In the formula, Z ¹ and Z ² each independently represent an aromatic ring or a heteroaromatic ring which may have a substituent. R ³ and R ⁴ each independently represent a hydrocarbon group having 20 or less carbon atoms which may have a substituent, and R ⁹ and R ¹⁰ may each independently have a hydrogen atom or a substituent. Represents an alkoxy group. Za ⁻ represents a counter anion present when charge neutralization is required.

5. 5. The on-press development type lithographic printing plate precursor as described in any one of 1 to 4 above, wherein an unexposed portion of the image recording layer can be removed by dampening water and / or printing ink.
6). The on-press development type lithographic printing plate precursor of 5 is subjected to image exposure with an infrared laser, then attached to a printing machine cylinder, and the image recording layer unexposed portion is removed with dampening water and printing ink. .

Although the operation of the present invention is not clear, it is considered as follows. That is, (A) a polymerization initiator group consisting of a sulfonium salt, an iodonium salt, a diazonium salt, an azinium salt, an oxime compound and a triazine compound and at least one of the compounds represented by the general formula (1) are linked by a covalent bond. When the polymer fine particles are used for the polymerizable composition, radicals are generated on the surface of the polymer fine particles by infrared laser exposure, and a strong image portion can be formed by polymerization with the (B) radical polymerizable compound. In addition, the radical polymerization initiator or compound is bonded to polymer fine particles, whereby the thermal stability is improved and the stability of the polymerizable composition is also improved. This is thought to be because the radical polymerization initiator according to the present invention is incorporated in the polymer fine particles so that the interaction with other compounds is suppressed and the radical polymerization initiator is thermally stabilized during raw storage. ing.
On the other hand, in the unexposed area, the image recording layer contains polymer fine particles, so that it can be easily dispersed in, for example, dampening water, an ink solvent, or an emulsified product of dampening water and ink. Developability can be imparted.

  ADVANTAGE OF THE INVENTION According to this invention, the lithographic printing original plate which can be directly made from digital signals, such as a computer, using various lasers, and has so-called direct plate making and high productivity can be obtained. In particular, an on-press development type lithographic printing plate precursor having good printing durability, stability over time, and stain resistance can be obtained.

The lithographic printing plate precursor according to the invention has an image recording layer on a hydrophilic support. If necessary, an undercoat layer can be provided between the support and the image recording layer, and a protective layer can be provided on the image recording layer. The protective layer may have a multilayer structure. You may have a backcoat layer in the back surface of a support body.
The present invention can be applied to any of the lithographic printing plate precursors of the plate making method in which development is performed using a conventional developer after exposure and the plate making method in on-press development without using the developer.
Hereinafter, each compound that can be used in the lithographic printing plate precursor according to the invention will be described in order.

[Image recording layer]
The image recording layer of the present invention contains a polymerizable composition containing a combination of (A) polymer fine particles, (B) a radical polymerizable compound, and (C) an infrared absorbing dye, and (A) the polymer fine particles are sulfonium. It is covalently linked to at least one compound selected from a polymerization initiator group consisting of a salt, iodonium salt, diazonium salt, azinium salt, oxime compound and triazine compound and a compound represented by the following general formula (1). It is a polymer fine particle. The compound represented by the following general formula (1) is a polymerization aid that promotes radical polymerization.

In general formula (1), A represents an aromatic hydrocarbon group or a heterocyclic group. X ¹ represents a divalent linking group selected from —O—, —S—, and —N (R ³ ) —. R ³ represents a hydrogen atom or an alkyl group which may have a substituent. R ¹ and R ² each independently represents a hydrogen atom or an alkyl group.

In the image recording layer of the present invention, (C) the infrared absorbing dye absorbs infrared rays from an infrared laser to polymerize and cure the exposed portion of the image recording layer. The polymerization initiator and the polymerization assistant are contained as a compound bonded to the polymer fine particles, but in addition, a polymerization initiator and a polymerization auxiliary not bonded to the polymer fine particles may be contained.
The image recording layer can also contain a binder polymer for the purpose of improving film properties. Further, the image recording layer may contain various known additives depending on the intended plate making method such as development processing or on-press development.
The image recording layer of the present invention will be described in detail below.

[Compounds covalently bonded to polymer particles]
The polymer fine particles of the present invention are at least one selected from a radical polymerization initiator group consisting of a sulfonium salt, an iodonium salt, a diazonium salt, an azinium salt, an oxime compound and a triazine compound, and a polymerization aid compound represented by the general formula (1). Two compounds are linked by a covalent bond. These radical polymerization initiators and polymerization assistants deteriorate in stability by interacting with infrared absorbing dyes and radical polymerizable compounds, but by introducing them into polymer fine particles, thermal stability is improved and polymerization is performed. The stability of the composition is also improved.
Further, the polymerization reaction with the radical polymerizable compound increases the film strength and improves the printing durability.

  The polymerization initiator and the polymerization assistant that are covalently bonded to the polymer fine particles will be described in more detail below. Among these polymerization initiators and polymerization assistants, sulfonium salts, iodonium salts, diazonium salts, azinium salts, and general formula (1) ) Is preferred.

<Sulphonium salt>
The sulfonium salt in the present invention can be represented by the following structural formula.

In general formula (A1-3), R ³¹ , R ³² and R ³³ each independently represents an aryl group having 20 or less carbon atoms, an alkyl group, an alkenyl group or an alkynyl group which may have 1 to 5 substituents. In view of reactivity and stability, an aryl group is desirable. Preferred substituents are alkyl groups having 1 to 12 carbon atoms, alkenyl groups having 1 to 12 carbon atoms, alkynyl groups having 1 to 12 carbon atoms, aryl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, An aryloxy group having 1 to 12 carbon atoms, a halogen atom, an alkylamino group having 1 to 12 carbon atoms, a dialkylamino group having 1 to 12 carbon atoms, an alkylamide group or arylamide group having 1 to 12 carbon atoms, a carbonyl group, Examples thereof include a carboxy group, a cyano group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms.
Z ₃₁ ^- represents a monovalent anion, a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, stability From the viewpoint of reactivity, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable, and more preferable are carboxylic acids described in JP-A-2001-343742 Ions, particularly preferred are carboxylate ions described in JP-A No. 2002-148790.

<Iodonium salt>
The iodonium salt in the present invention can be represented by the following structural formula.

In General Formula (A1-2), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 5 substituents, and preferred substituents include 1 to 12 carbon atoms. An alkyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, Halogen atom, C1-C12 alkylamino group, C1-C12 dialkylamino group, C1-C12 alkylamide group or arylamide group, carbonyl group, carboxy group, cyano group, sulfonyl group, carbon Examples thereof include a thioalkyl group having 1 to 12 carbon atoms and a thioaryl group having 1 to 12 carbon atoms.
Z ₂₁ ⁻ represents a monovalent anion, which is a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, and is stable From the viewpoint of reactivity, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, and carboxylate ions are preferable.

<Diazonium salt>
The diazonium salt in the present invention can be represented by the following structural formula.

In General Formula (A1-1), Ar ¹¹ represents an aryl group having 20 or less carbon atoms which may have 1 to 5 substituents, and preferred substituents include alkyl groups having 1 to 12 carbon atoms and carbon numbers. 1-12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1 -12 alkylamino group, C1-C12 dialkylamino group, C1-C12 alkylamide group or arylamide group, carbonyl group, carboxy group, cyano group, sulfonyl group, C1-C12 thioalkyl Group, a C1-C12 thioaryl group is mentioned.
Z ₁₁ ⁻ represents a monovalent anion, which is a halide ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, and is stable. From the above viewpoint, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, and sulfinate ion are preferable.

<Azinium salt>
The azinium salt in the present invention can be represented by the following structural formula.

In General Formula (A1-4), R ¹ represents a monovalent organic group, and R ² to R ⁶ each independently represent a hydrogen atom, a halogen atom, or a monovalent organic group. X ⁻ represents an anion.
When R ^{1 to} R ⁶ represent a monovalent organic group, examples of the monovalent organic group include an amino group, a substituted amino group, a substituted carbonyl tomb, a hydroxyl group, a substituted oxy group, a thiol group, a thioether group, Silyl group, nitro group, cyano group, alkyl group, alkenyl group, aryl group, heterocyclic group, sulfo group, substituted sulfonyl group, sulfonate group, substituted sulfinyl group, phosphono group, substituted phosphono group, phosphonate group, substituted phosphonate group, In the case where introduction is possible, it may further have a substituent.

<Oxime compound>
The oxime compound in the present invention can be represented by the following structural formula described in JP-A-2005-215147.

In General Formula (A1-5), X represents a carbonyl group, a sulfonyl group, or a sulfinyl group, and Y represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a benzoyl group, or a heterocyclic group.
Q and Z each independently represent a monovalent substituent consisting of a nonmetallic atom, and these are one or more selected from the group consisting of a hydrogen atom, an oxygen atom, a halogen atom, a nitrogen atom, and a sulfur atom You may have a substituent containing an atom.

<Triazine compound>
The triazine compound in the present invention can be represented by the following structural formula described in JP-A-2006-330155.

In General Formula (A1-6), R ¹ and R ² are halomethyl groups, and Y is an organic group having 5 or more carbon atoms. Examples of the halomethyl group include a trichloromethyl group, a tribromomethyl group, a dichloromethyl group, and a dibromomethyl group. Examples of the organic group having 5 or more carbon atoms include a phenyl group that may have a substituent, Examples include naphthyl group, styryl group, styrylphenyl group, furylvinyl group, quaternized aminoethylamino group.

<Compound represented by the general formula (1)>

In general formula (1), A represents an aromatic hydrocarbon group or a heterocyclic group. X ¹ represents a divalent linking group selected from —O—, —S—, and —N (R ³ ) —. R ³ represents a hydrogen atom or an alkyl group which may have a substituent. R ¹ and R ² each independently represents a hydrogen atom or an alkyl group.

Here, in the general formula (1), the aromatic hydrocarbon group represented by A includes a benzene ring, a ring in which 2 to 3 benzene rings form a condensed ring, a benzene ring and a 5-membered unsaturated ring. In which a condensed ring is formed. 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 more preferable.
The aromatic hydrocarbon group may have a substituent, and examples of such a substituent include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, an alkenyl group, a substituted alkenyl group, and An alkoxy group is mentioned.

As the heterocyclic group represented by A, a pyrrole ring group, a furan ring group, a thiophene ring group, a benzopyrrole ring group, a benzofuran ring group, a benzothiophene ring group, a pyrazole ring group, an isoxazole ring group, an isothiazole ring group, Indazole ring group, benzisoxazole ring group, benzoisothiazole ring group, imidazole ring group, oxazole ring group, thiazole ring group, benzimidazole ring group, benzoxazole ring group, benzothiazole ring group, pyridine ring group, quinoline ring Group, isoquinoline ring group, pyridazine ring group, pyrimidine ring group, pyrazine ring group, phthalazine ring group, quinazoline ring group, quinoxaline ring group, acylidene ring group, phenanthridine ring group, carbazole ring group, purine ring group, pyran ring Group, piperidine ring group, piperazine ring group, morpholine ring group, indole ring group, Ndorijin ring group, a chromene ring group, a cinnoline ring group, an acridine ring group, a phenothiazine ring group, a tetrazole ring group, a triazine ring group, and the like.
The heterocyclic group may have a substituent, and examples of such a substituent include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, an alkenyl group, a substituted alkenyl group, and an alkoxy group. Is mentioned.

In general formula (1), examples of the alkyl group represented by R ¹ and R ² include linear, branched, and cyclic alkyl groups having 1 to 20 carbon atoms. Examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl Group, isopropyl group, isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclohexyl group, cyclopentyl group, 2 -Norbornyl group can be mentioned. 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.

  Such an alkyl group may have a substituent, and examples of the substituent that can be included and specific examples thereof include those described in paragraphs [0080] to [0097] of JP-A-2005-59446. be able to.

Of the above R ¹ and R ² , it is particularly preferred that both R ¹ and R ² are hydrogen atoms.

Then, ^X 1 in the general formula (1) is, -O -, - S -, - N (R 3) - are preferred in terms of sensitivity, -N ^{(R 3)} - it is the sensitivity and storage is More preferable from the viewpoint of stability.

Here, R ³ is any one of a hydrogen atom, an optionally substituted alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic ring. In particular, a hydrogen atom or an alkyl group which may have a substituent is preferable. Examples of the substituent that such an alkyl group can have include those described in paragraph numbers [0080] to [0097] of JP-A-2005-59446.

Among these, R ³ preferably has at least one of —CO ₂ — and —CON (R ⁸ ) — in its structure, and the most preferable structure of R ³ is represented by the following formula (i): Or a structure having an amide structure represented by formula (ii), particularly a structure having an amide structure represented by formula (ii).

In the above formula, R ⁶ , R ⁷ and R ⁸ each independently represent a hydrogen atom or a monovalent substituent, and Z represents a monovalent substituent. Such a monovalent substituent has the same meaning as R ¹ or R ² in the general formula (1).

  From the viewpoint of selecting a covalently bonded compound from the above, it can be generally determined in consideration of the reactivity with the infrared absorbing dye. The polymer fine particles may be introduced at the time of polymerization, or may be introduced by utilizing a polymer reaction after the polymerization.

[Polymer fine particles]
The polymer fine particles of the present invention are not particularly limited, and examples thereof include microcapsules obtained by interfacial polymerization, microgels, or polymer fine particles obtained by radical polymerization.
The fine polymer particles used in the present invention can be modified with the radical polymerization initiator or the compound represented by the general formula (1). From such a viewpoint, the main chain of the particle forming material is preferably polymer fine particles obtained by interfacial polyaddition rather than polymer fine particles obtained by radical polymerization.

(Polymer fine particles obtained by interfacial polymerization)
The microgel by interfacial polymerization used in the present invention can be modified with a radical polymerization initiator or a compound represented by the general formula (1). As the interfacial polymerization, there are an interfacial polyaddition type such as polyurethane and polyurea and an interfacial polycondensation type such as polyester and polyamide.
Polyurethane and polyurea obtained by interfacial polyaddition are preferred, and polymer fine particles in which urethane and urea coexist are particularly preferred.
Polyurethane is a polymer containing a urethane bond (—NH—CO—O—) in the main chain, polyurea is a polymer containing a urea bond (—NH—CO—NH—) in the main chain, and polyester is an ester bond. The polymer is a polymer containing (—CO—O—) in the main chain, and the polyamide is a polymer containing an amide bond (—CO—NH—) in the main chain.

Polyurethanes, polyureas and copolymers thereof can be synthesized by reacting polyols or polyamines with polyvalent isocyanates. It can also be synthesized by a condensation reaction between a polyvalent amine produced by hydrolysis of a polyvalent isocyanate and a polyvalent isocyanate. In the synthesis reaction, it is preferable to synthesize an adduct obtained by reacting 1 mol of n-valent polyol with n mol of polyvalent isocyanate as an intermediate, and then react the adduct.
In an actual reaction, an excess amount (more than n moles) of a polyvalent isocyanate is often added to the reaction system with respect to 1 mole of an n-valent polyol.

  In addition to the polyol, a nucleophilic compound (eg, alcohol, phenol, thiol, amine) having a nucleophilic group (eg, hydroxy group, mercapto group, amino group) may be reacted with a polyvalent isocyanate. In some cases, an adduct of a polyol and a polyvalent isocyanate is reacted with a nucleophilic compound to partially modify and then be synthesized.

When the radical polymerization initiator and the compound represented by the general formula (1) have a nucleophilic group per se, they are reacted with a polyvalent isocyanate as it is. When the compound itself does not have a nucleophilic group, the radical polymerization initiator and the compound represented by the general formula (1) are introduced into the polyol or the nucleophilic compound used together with the polyol, and then reacted with the polyvalent isocyanate. Let Alternatively, an isocyanate adduct may be synthesized by reacting with a polyvalent isocyanate, and the adduct may be further reacted.
In the case of a microcapsule, it can be obtained by applying the above-described production method and containing an inclusion.

<Radical polymerization initiator having nucleophilic group and compound represented by general formula (1)>
The compound containing a radical polymerization initiator used for the synthesis of the polyaddition type polymer fine particles is preferably one represented by the following formula (A-1).

L ¹ (In) _m (Z) _n (A-1)
In the formula (A-1), L ¹ is an m + n-valent linking group, m and n are each independently an integer of 1 to 100, and In is represented by a radical polymerization initiator or the general formula (1). And Z is a nucleophilic group.
L ¹ represents a divalent or higher aliphatic group, a divalent or higher aromatic group, a divalent or higher heterocyclic group, —O—, —S—, —NH—, —N <, —CO—, —SO. -, - SO ₂ - or preferably a combination thereof.
m and n are each independently preferably an integer of 1 to 50, more preferably an integer of 1 to 20, still more preferably an integer of 1 to 10, and an integer of 1 to 5 Most preferably it is.
Z is preferably OH, SH or NH ₂ , more preferably OH or NH ₂ , and most preferably OH.

  Specific examples (A-1-1) to (A-1-18) of the compound represented by the radical polymerization initiator having a nucleophilic group suitably used in the present invention and the general formula (1): Although (A-2-1) to (A-2-10) are listed, the present invention is not limited to these.

  Two or more compounds represented by formula (A-1) may be used in combination. An adduct of a compound containing an ethylenic double bond and a polyvalent isocyanate and an adduct of another polyol and a polyvalent isocyanate can also be used in combination. Further, an adduct may be synthesized (modify the adduct) by reacting an adduct of another polyol with a polyvalent isocyanate and a compound represented by the general formula (A-1).

  In addition to the compound represented by formula (A-1) or the polyol, a polyvalent amine may be used for forming the shell polymer. The polyvalent amine is preferably water-soluble. Examples of the polyvalent amine include ethylenediamine, propylenediamine, phenylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

<Multivalent isocyanate>
The polyvalent isocyanate used in the present invention is preferably a diisocyanate defined by the following formula (A-2).
OCN-L ⁴ -NCO (A-2)

In the formula (A-2), L ⁴ is a divalent linking group. L ⁴ is preferably a divalent group selected from the group consisting of an alkylene group, a substituted alkylene group, an arylene group, a substituted arylene group, and combinations thereof. A divalent linking group comprising a combination of an alkylene group and an arylene group is particularly preferred.
The alkylene group may have a cyclic structure or a branched structure. The alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, still more preferably 1 to 10 carbon atoms, and most preferably 1 to 8 carbon atoms.
Examples of the substituent of the substituted alkylene group and the substituted alkyl group include a halogen atom, an oxo group (═O), a thioxo group (═S), an aryl group, a substituted aryl group, and an alkoxy group.
The arylene group is preferably phenylene, and most preferably p-phenylene.
Examples of the substituent of the substituted arylene group and the substituted aryl group include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, and an alkoxy group.

  Examples of diisocyanates include xylylene diisocyanate (eg, m-xylylene diisocyanate, p-xylylene diisocyanate), 4-chloro-m-xylylene diisocyanate, 2-methyl-m-xylylene diisocyanate. Narate, phenylene diisocyanate (eg, m-phenylene isocyanate, p-phenylene diisocyanate), toluylene diisocyanate (eg, 2,6-toluylene diisocyanate, 2,4-toluylene diisocyanate), naphthalene Diisocyanates (eg, naphthalene-1,4-diisocyanates), isophorone diisocyanates, alkylene diisocyanates (eg, trimethylene diisocyanates, hexamethylene diisocyanates, propylene-1,2-diisocyanates) , Butylene-1,2-di Sosocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, dicyclohexylmethane-1,4-diisocyanate, 1 , 4-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane), diphenylmethane-4,4′-diisocyanate, 3,3′-dimethoxybiphenyl diisocyanate, 3,3 ′ -Dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, 4,4'-diphenylhexafluoropropane diisocyanate and lysine diisocyanate.

  Isophorone diisocyanate, xylylene diisocyanate and toluylene diisocyanate are preferred, isophorone diisocyanate and xylylene diisocyanate are more preferred, and isophorone diisocyanate and m-xylylene diisocyanate are particularly preferred. Two or more kinds of diisocyanates may be used in combination.

(Polymer fine particles obtained by radical polymerization)
Since the compound represented by the general formula (1) (hereinafter also referred to as a carboxylic acid derivative of the general formula (1)) is thermally stable, polymer fine particles can be synthesized even by utilizing radical polymerization. Hereinafter, the carboxylic acid derivative of the general formula (1) used for the synthesis of polymer fine particles by radical polymerization will be described.

  As the carboxylic acid derivative of the general formula (1) used for the synthesis of polymer fine particles by radical polymerization, a compound in which an ethylenically unsaturated double bond is directly bonded to the carboxylic acid derivative of the general formula (1), and a linking group Examples thereof include a compound represented by the following formula (A-3) bonded to the carboxylic acid derivative of the general formula (1).

L ² (A) _m (Y) _n (A-3)
In Formula (A-3), L ² is an m + n-valent linking group, m and n are each independently an integer of 1 to 100, and A is a monovalent group including the carboxylic acid derivative of General Formula (1). And Y is an ethylenically unsaturated double bond.
L ² represents a divalent or higher aliphatic group, a divalent or higher aromatic group, a divalent or higher heterocyclic group, —O—, —S—, —NH—, —N <, —CO—, —SO. -, - SO ₂ - or preferably a combination thereof. m and n are each independently preferably an integer of 1 to 50, more preferably an integer of 1 to 20, still more preferably an integer of 1 to 10, and an integer of 1 to 4. Most preferred.

  Specific examples of the carboxylic acid derivative of the general formula (1) having a polymerizable group used for the synthesis of polymer fine particles by radical polymerization are given below, but the present invention is not limited thereto.

  The average particle size of the polymer fine particles of the present invention is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is still more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good printing durability and stability over time can be obtained.

  The addition amount of the polymer fine particles to the image recording layer is preferably 10 to 80% by mass, and more preferably 15 to 60% by mass in terms of solid content.

[(B) Radical polymerizable compound]
The radical polymerizable compound used for the image recording layer in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and has at least one, preferably two or more terminal ethylenically unsaturated bonds. Selected from compounds. These have chemical forms such as monomers, prepolymers, ie dimers, trimers and oligomers, or 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 a polyhydric alcohol compound and an amide of an unsaturated carboxylic acid and a polyvalent amine compound are used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxy group, an amino group or a mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and a monofunctional or polyfunctional compound. 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. These are disclosed in JP-T-2006-508380, JP-A-2002-287344, JP-A-2008-256850, JP-A-2001-342222, JP-A-9-179296, JP-A-9-179297. JP-A-9-179298, JP-A-2004-294935, JP-A-2006-243493, JP-A-2002-275129, JP-A-2003-64130, JP-A-2003-280187, It is described in references including Kaihei 10-333321.

  Specific examples of the monomer of the ester of a polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, Examples include trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, isocyanuric acid ethylene oxide (EO) -modified triacrylate, and polyester acrylate oligomer. Methacrylic acid esters include tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis [p- (3-methacryloxy-2-hydroxypropoxy) phenyl ] Dimethylmethane, bis- [p- (methacryloxyethoxy) phenyl] dimethylmethane, and the like. Specific examples of amide monomers of polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis-methacrylic. Examples include amide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide.

In addition, urethane-based addition-polymerizable compounds produced by using an addition reaction between an isocyanate and a hydroxy group are also suitable, and specific examples thereof include, for example, one molecule described in Japanese Patent Publication No. 48-41708. A vinyl containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxy group represented by the following general formula (b) to a polyisocyanate compound having two or more isocyanate groups. A urethane compound etc. are mentioned.
^{_{CH 2 = C (R 4)}} COOCH 2 CH (R 5) OH (b)
(However, R ⁴ and R ⁵ each independently represent H or CH _3. )

  Also, urethanes described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-A-2003-344997, and JP-A-2006-65210. Acrylates, JP-B 58-49860, JP-B 56-17654, JP-B 62-39417, JP-B 62-39418, JP-A 2000-250211, JP-A 2007-94138 Urethane compounds having an ethylene oxide-based skeleton described in the publication, and urethane compounds having a hydrophilic group described in US Pat. No. 7,153,632, JP-T 8-505958, JP-A 2007-293221, and JP-A 2007-293223. Are also suitable.

  Among them, tris (acryloyloxyethyl) isocyanurate, bis (acryloyloxyethyl) hydroxyethyl isocyanurate, etc. are excellent in the balance between the hydrophilicity involved in on-press developability and the polymerization ability involved in printing durability. Isocyanuric acid ethylene oxide modified acrylates are particularly preferred.

  Details of the method of use such as the structure of these radically polymerizable compounds, whether they are used alone or in combination, and the amount added can be arbitrarily set in accordance with the performance design of the final lithographic printing plate precursor. The polymerizable compound is preferably used in the range of 5 to 75% by mass, more preferably 10 to 70% by mass, and particularly preferably 15 to 60% by mass with respect to the total solid content of the image recording layer.

[(C) Infrared absorbing dye]
The infrared absorbing dye has a function of converting the absorbed infrared light into heat and a function of being excited by the infrared light and transferring electrons and / or energy to a radical polymerization initiator described later. The infrared absorbing dye used in the present invention is a dye having an absorption maximum at a wavelength of 760 to 1200 nm.

As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes Is mentioned.
Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferred, and particularly preferred examples include cyanine dyes represented by the following general formula (a).

In the general formula (a), X ¹ represents a hydrogen atom, a halogen ^{atom, -N (R 9) (R} 10), - X ² -L ¹ or a group shown below. Here, R ⁹ and R ¹⁰ may be the same or different and each may have a substituent, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, a hydrogen atom R ⁹ and R ¹⁰ may be bonded to each other to form a ring. Of these, a phenyl group is preferred (—NPh ₂ ). X ² represents an oxygen atom or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, a heteroaryl group, or a hydrocarbon group having 1 to 12 carbon atoms including a hetero atom. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. In the group shown below, Xa ^- has Za described later ^- is defined as for, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom .

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the image recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms. R ¹ and R ² may be connected to each other to form a ring, and when forming a ring, it is particularly preferable to form a 5-membered ring or a 6-membered ring.

Ar ¹ and Ar ² may be the same or different and each represents an aryl group which may have a substituent. Preferred aryl groups include a benzene ring and a naphthalene ring. Preferred substituents include hydrocarbon groups having 12 or less carbon atoms, halogen atoms, and alkoxy groups having 12 or less carbon atoms. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxy groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (a) has an anionic substituent in its structure and charge neutralization is not necessary. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of the storage stability of the image recording layer coating solution. , Hexafluorophosphate ions, and aryl sulfonate ions.

  More preferred infrared absorbing dyes in the present invention include cyanine dyes represented by the following general formula (2).

In the formula, Z ¹ and Z ² each independently represent an aromatic ring or a heteroaromatic ring which may have a substituent. Preferred aromatic rings include a benzene ring and a naphthalene ring. Preferred substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, an alkoxy group having 12 or less carbon atoms, a hydrocarbon group having 12 or less carbon atoms, and 12 carbon atoms. Most preferred are not more than alkoxy groups.
R ³ and R ⁴ each independently represent a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxy groups, and sulfo groups.
R ⁹ and R ¹⁰ each independently represent a hydrogen atom or an alkoxy group which may have a substituent. Za ⁻ represents a counter anion present when charge neutralization is required. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of the storage stability of the image recording layer coating solution. , Hexafluorophosphate ions, and aryl sulfonate ions.

Specific examples of the cyanine dye represented by formula (a) that can be suitably used include compounds described in paragraphs [0017] to [0019] of JP-A No. 2001-133969, and JP-A No. 2002-023360. Paragraph numbers [0016] to [0021] of JP-A No. 2002-040638, compounds described in paragraph Nos. [0012] to [0037] of JP-A No. 2002-040638, preferably paragraph Nos. [0034] of JP-A No. 2002-278057 [0041], compounds described in paragraph numbers [0080] to [0086] of JP 2008-195018 A, most preferably compounds described in paragraph numbers [0035] to [0043] of JP 2007-90850 A Is mentioned.
In addition, compounds described in paragraph numbers [0008] to [0009] of JP-A No. 5-5005 and paragraph numbers [0022] to [0025] of JP-A No. 2001-222101 can also be preferably used.

  Moreover, only 1 type may be used for these infrared absorption dyes, 2 or more types may be used together, and infrared absorption pigments other than an infrared absorption dye may be used together. As the pigment, compounds described in JP 2008-195018 A [0072] to [0076] are preferable.

  The content of the infrared absorbing dye in the image recording layer in the present invention is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass of the total solid content of the image recording layer. .

[Radical polymerization initiator]
The image recording layer of the present invention may contain a known radical polymerization initiator that is not bonded to the polymer fine particles in addition to the radical polymerization initiator that is covalently bonded to the polymer fine particles. Examples of such radical polymerization initiators include (a) organic halides, (b) carbonyl compounds, (c) azo compounds, (d) organic peroxides, (e) metallocene compounds, and (f) azide compounds. (G) hexaarylbiimidazole compound, (h) organic borate compound, (i) disulfone compound, (j) oxime ester compound, (k) onium salt compound. Among them, there can be mentioned sulfonium salts, iodonium salts, diazonium salts, azinium salts, oxime compounds and triazine compounds listed as polymerization initiators to which the aforementioned polymer fine particles can be bonded.
Specific examples thereof include the compounds described in JP-A-2008-195018.

  The radical polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass with respect to the total solid content of the image recording layer. Can be added.

[Binder polymer]
In the image recording layer of the present invention, a binder polymer can be used in order to improve the film strength of the image recording layer. As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and polymers having film properties are preferred. Of these, acrylic resins, polyvinyl acetal resins, and polyurethane resins are preferable.

  Among them, as a binder polymer suitable for the present invention, as described in JP-A-2008-195018, a crosslinkable functional group for improving the film strength of the image portion is a main chain or a side chain, preferably a side chain. Have the following. Crosslinking is formed between the polymer molecules by the crosslinkable group, and curing is accelerated.

  The crosslinkable functional group is preferably an ethylenically unsaturated group such as a (meth) acryl group, vinyl group, allyl group, or styryl group, or an epoxy group, and these groups are introduced into the polymer by polymer reaction or copolymerization. be able to. For example, a reaction between an acrylic polymer or polyurethane having a carboxy group in the side chain and polyurethane and glycidyl methacrylate, or a reaction between a polymer having an epoxy group and an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid can be used.

  The content of the crosslinkable group in the binder polymer is preferably 0.1 to 10.0 mmol, more preferably 0.25 to 7.0 mmol, and most preferably 0.5 to 5.5 mmol per 1 g of the binder polymer. .

  In the present invention, the binder polymer preferably further has a hydrophilic group. The hydrophilic group contributes to imparting on-press developability to the image recording layer. In particular, the coexistence of the crosslinkable group and the hydrophilic group makes it possible to achieve both printing durability and developability.

  Examples of the hydrophilic group include a hydroxy group, a carboxy group, an alkylene oxide structure, an amino group, an ammonium group, an amide group, a sulfo group, and a phosphoric acid group. Among them, an alkylene oxide unit having 2 or 3 carbon atoms An alkylene oxide structure having 1 to 9 is preferable. In order to impart a hydrophilic group to the binder polymer, a monomer having a hydrophilic group may be copolymerized.

  In the present invention, a lipophilic group such as an alkyl group, an aryl group, an aralkyl group, and an alkenyl group can be introduced into the binder polymer in order to control the inking property. Specifically, a lipophilic group-containing monomer such as an alkyl methacrylate may be copolymerized.

  Specific examples (1) to (11) of the binder polymer used in the present invention are shown below, but the present invention is not limited thereto. The ratio of repeating units is a molar ratio.

  The binder polymer in the present invention preferably has a mass average molar mass (Mw) of 2000 or more, more preferably 5000 or more, and still more preferably 10,000 to 300,000.

[Other ingredients]
The image recording layer of the present invention may further contain the following components as necessary.

(1) Low molecular weight hydrophilic compound The image-recording layer in the invention may contain a low molecular weight hydrophilic compound in order to improve the on-press developability without reducing the printing durability.
As the low molecular weight hydrophilic compound, for example, as the water-soluble organic compound, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like glycols and ether or ester derivatives thereof, glycerin, Polyols such as pentaerythritol and tris (2-hydroxyethyl) isocyanurate, organic amines such as triethanolamine, diethanolamine and monoethanolamine and salts thereof, organic sulfones such as alkylsulfonic acid, toluenesulfonic acid and benzenesulfonic acid Acids and salts thereof, organic sulfamic acids such as alkylsulfamic acid and salts thereof, organic sulfuric acids such as alkylsulfuric acid and alkylethersulfuric acid and salts thereof, phenylphosphonic acid Organic phosphonic acids and salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, organic carboxylic acids and salts thereof such as amino acids, betaines, and the like.

  Among these, in the present invention, it is preferable to contain at least one selected from the group consisting of polyols, organic sulfates, organic sulfonates, and betaines.

  Specific examples of organic sulfonates include alkyl sulfonates such as sodium n-butyl sulfonate, sodium n-hexyl sulfonate, sodium 2-ethylhexyl sulfonate, sodium cyclohexyl sulfonate, and sodium n-octyl sulfonate. Sodium 5,8,11-trioxapentadecane-1-sulfonate, sodium 5,8,11-trioxaheptadecane-1-sulfonate, 13-ethyl-5,8,11-trioxaheptadecane-1; Alkyl sulfonates containing ethylene oxide chains such as sodium sulfonate, 5,8,11,14-tetraoxatetradecosane-1-sodium sulfonate; sodium benzenesulfonate, sodium p-toluenesulfonate, p-hydroxy Benzenesulfo Acid sodium, sodium p-styrenesulfonate, sodium dimethyl-5-sulfonate isophthalate, sodium 1-naphthylsulfonate, sodium 4-hydroxynaphthylsulfonate, disodium 1,5-naphthalenedisulfonate, 1,3,6 -Aryl sulfonates such as trisodium naphthalene trisulfonate, paragraph numbers [0026] to [0031] of JP 2007-276454 A, and paragraph numbers [0020] to [0047] of JP 2009-154525 A And the compounds described. The salt may be a potassium salt or a lithium salt.

  Organic sulfates include sulfates of alkyl, alkenyl, alkynyl, aryl or heterocyclic monoethers of polyethylene oxide. The number of ethylene oxide units is preferably 1 to 4, and the salt is preferably a sodium salt, potassium salt or lithium salt. Specific examples thereof include compounds described in paragraph numbers [0034] to [0038] of JP-A-2007-276454.

  As the betaines, compounds having 1 to 5 carbon atoms of the hydrocarbon substituent on the nitrogen atom are preferable. Specific examples include trimethylammonium acetate, dimethylpropylammonium acetate, 3-hydroxy-4-trimethyl. Ammonioobylate, 4- (1-pyridinio) butyrate, 1-hydroxyethyl-1-imidazolioacetate, trimethylammonium methanesulfonate, dimethylpropylammonium methanesulfonate, 3-trimethylammonio-1-propanesulfonate, Examples include 3- (1-pyridinio) -1-propanesulfonate.

  The above low molecular weight hydrophilic compound has a small hydrophobic part structure and almost no surface-active action, so that dampening water penetrates into the exposed part of the image recording layer (image part) and the hydrophobicity and film strength of the image part. Ink acceptability and printing durability of the image recording layer can be maintained satisfactorily.

The amount of these low molecular weight hydrophilic compounds added to the image recording layer is preferably 0.5% by mass or more and 20% by mass or less of the total solid content of the image recording layer. More preferably, they are 1 mass% or more and 15 mass% or less, More preferably, they are 2 mass% or more and 10 mass% or less. In this range, good on-press developability and printing durability can be obtained.
These compounds may be used alone or in combination of two or more.

(2) Grease Sensitizer In the image recording layer of the present invention, a lipid sensitizer such as a phosphonium compound, a nitrogen-containing low molecular weight compound, or an ammonium group-containing polymer is used for the image recording layer in order to improve the inking property. be able to. In particular, when an inorganic layered compound is contained in the protective layer, these compounds function as a surface coating agent for the inorganic layered compound, and prevent a decrease in the inking property during printing by the inorganic layered compound.

  Suitable phosphonium compounds include phosphonium compounds described in JP-A-2006-297907 and JP-A-2007-50660. Specific examples include tetrabutylphosphonium iodide, butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 1,4-bis (triphenylphosphonio) butanedi (hexafluorophosphate), 1,7-bis (tri Phenylphosphonio) heptane sulfate, 1,9-bis (triphenylphosphonio) nonane = naphthalene-2,7-disulfonate, and the like.

  Examples of the nitrogen-containing low molecular weight compound include amine salts and quaternary ammonium salts. Also included are imidazolinium salts, benzoimidazolinium salts, pyridinium salts, and quinolinium salts. Of these, quaternary ammonium salts and pyridinium salts are preferable. Specific examples include tetramethylammonium = hexafluorophosphate, tetrabutylammonium = hexafluorophosphate, dodecyltrimethylammonium = p-toluenesulfonate, benzyltriethylammonium = hexafluorophosphate, benzyldimethyloctylammonium = hexafluorophosphate. Fert, benzyldimethyldodecyl ammonium = hexafluorophosphate, paragraph numbers [0021] to [0037] of JP-A-2008-284858, paragraph numbers [0030] to [0057] of JP-A-2009-90645 Compound etc. are mentioned.

  The ammonium group-containing polymer may be any polymer as long as it has an ammonium group in its structure, but a polymer containing 5 to 80 mol% of a (meth) acrylate having an ammonium group in the side chain as a copolymerization component is preferable. . Specific examples include the polymers described in paragraph numbers [0089] to [0105] of JP2009-208458A.

  The ammonium salt-containing polymer has a reduced specific viscosity (unit: ml / g) determined by the following measurement method, preferably in the range of 5 to 120, more preferably in the range of 10 to 110, 15 Those in the range of ~ 100 are particularly preferred. When the said reduced specific viscosity is converted into a mass mean molar mass (Mw), 10,000-150,000 are preferable, 17000-140000 are more preferable, 20000-130000 are especially preferable.

<Measurement method of reduced specific viscosity>
Weigh 3.33 g of 30% polymer solution (1 g as solid content) into a 20 ml volumetric flask and make up with N-methylpyrrolidone. This solution is allowed to stand for 30 minutes in a thermostatic bath at 30 ° C., put in an Ubbelohde reduced viscosity tube (viscosity constant = 0.010 cSt / s), and the time for flowing down at 30 ° C. is measured. The measurement is performed twice with the same sample, and the average value is calculated. Similarly, in the case of a blank (only N-methylpyrrolidone), the reduced specific viscosity (ml / g) was calculated from the following formula.

Specific examples of the ammonium group-containing polymer are shown below.
(1) 2- (Trimethylammonio) ethyl methacrylate = p-toluenesulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 10/90 Mw 45,000)
(2) 2- (Trimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80 Mw 60,000)
(3) 2- (Ethyldimethylammonio) ethyl methacrylate = p-toluenesulfonate / hexyl methacrylate copolymer (molar ratio 30/70 Mw 45,000)
(4) 2- (Trimethylammonio) ethyl methacrylate = hexafluorophosphate / 2-ethylhexyl methacrylate copolymer (molar ratio 20/80 Mw 60,000)
(5) 2- (Trimethylammonio) ethyl methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40/60 Mw 7 million)
(6) 2- (Butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 25/75 Mw 650,000)
(7) 2- (Butyldimethylammonio) ethyl acrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80 Mw 65,000)
(8) 2- (butyldimethylammonio) ethyl methacrylate = 13-ethyl-5,8,11-trioxa-1-heptadecanesulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80 Mw 75,000)
(9) 2- (butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate / 2-hydroxy-3-methacryloyloxypropyl methacrylate copolymer (molar ratio 15/80/5 (Mw 650,000)

  The content of the sensitizer is preferably 0.01 to 30.0% by mass, more preferably 0.1 to 15.0% by mass and 1 to 10% by mass with respect to the total solid content of the image recording layer. Is more preferable.

(3) Others Further, as other components, surfactants, colorants, print-out agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic fine particles, inorganic layered compounds, co-sensitizers or chain transfer agents, etc. Can be added. Specifically, paragraph numbers [0114] to [0159] of Japanese Patent Application Laid-Open No. 2008-284817, paragraph numbers [0023] to [0027] of Japanese Patent Application Laid-Open No. 2006-091479, and US Patent Publication No. 2008/0311520. The compound and the addition amount described in paragraph [0060] of FIG.

(Formation of image recording layer)
The image recording layer in the present invention is a coating solution prepared by dispersing or dissolving the necessary components in a known solvent as described in paragraphs [0142] to [0143] of JP-A-2008-195018, for example. This is prepared by coating the substrate by a known method such as bar coater coating and drying. The image recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the application, but is generally preferably 0.3 to 3.0 g / m ² . Within this range, good sensitivity and good film characteristics of the image recording layer can be obtained.

[Undercoat layer]
In the lithographic printing plate precursor according to the invention, an undercoat layer (sometimes referred to as an intermediate layer) is preferably provided between the image recording layer and the support. The undercoat layer enhances the adhesion between the support and the image recording layer in the exposed area, and easily peels off the image recording layer from the support in the unexposed area. Contributes to improvement. In the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, thereby preventing the heat generated by the exposure from diffusing to the support and reducing the sensitivity.

  As the compound used for the undercoat layer, an undercoat layer having a compound having an acid group such as phosphonic acid, phosphoric acid, or sulfonic acid is preferably used. Further, those having an adsorbing group capable of being adsorbed on the surface of the support and a crosslinkable group for improving adhesion to the image recording layer are preferable. These compounds may be low molecular weight or high molecular weight polymers. Moreover, you may use these compounds in mixture of 2 or more types as needed.

In the case of a high molecular polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group is preferable. The adsorbable adsorptive group to the surface of the support, a phenolic hydroxy group, a carboxy _{group, -PO 3 H 2, -OPO 3} H 2, -CONHSO 2 -, - SO 2 NHSO 2 -, - COCH 2 COCH 3 Is preferred. As the hydrophilic group, a sulfo group is preferable. The crosslinkable group is preferably a methacryl group or an allyl group.
This polymer may have a crosslinkable group introduced by salt formation between the polar substituent of the polymer, a substituent having a counter charge and a compound having an ethylenically unsaturated bond, Other monomers, preferably hydrophilic monomers, may be further copolymerized.
Specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679 and an ethylenic compound described in JP-A-2-304441. The phosphorus compound which has a heavy bond reactive group is mentioned suitably. Crosslinkable groups (preferably ethylenically unsaturated bond groups) described in JP-A-2005-238816, JP-A-2005-12549, JP-A-2006-239867, and JP-A-2006-215263, the surface of the support Those containing a low-molecular or high-molecular compound having a functional group that interacts with each other and a hydrophilic group are also preferably used. More preferable are polymer polymers having an adsorbable group, a hydrophilic group, and a crosslinkable group that can be adsorbed on the support surface described in JP-A Nos. 2005-125749 and 2006-188038.

The content of unsaturated double bonds in the polymer resin for the undercoat layer is preferably 0.1 to 10.0 mmol, and most preferably 0.2 to 5.5 mmol per 1 g of the polymer.
The polymer for the undercoat layer preferably has a mass average molar mass of 5000 or more, more preferably 10,000 to 300,000.

  The undercoat layer of the present invention comprises, in addition to the above undercoat compound, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, an amino group, or a functional group having a polymerization inhibiting ability, in order to prevent contamination over time. Compounds having a group that interacts with the surface of an aluminum support (for example, 1,4-diazabicyclo [2,2,2] octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil , Sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, and the like.

The undercoat layer is applied by a known method. 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.

[Support]
As the support used in the lithographic printing plate precursor according to the invention, a known support is used. Of these, an aluminum plate that has been roughened and anodized by a known method is preferred.
In addition, the above aluminum plate is optionally subjected to micropore enlargement treatment or sealing treatment of an anodized film described in JP-A Nos. 2001-253181 and 2001-322365, and US Pat. 714,066, 3,181,461, 3,280,734 and 3,902,734, or alkali metal silicates as described in U.S. Pat. Surface hydrophilization treatment with polyvinylphosphonic acid or the like as described in each specification of 3,276,868, 4,153,461 and 4,689,272 is appropriately performed and performed. be able to.
The support preferably has a center line average roughness of 0.10 to 1.2 μm.

  If necessary, the support of the present invention includes an organic polymer compound described in JP-A-5-45885 and a silicon alkoxy compound described in JP-A-6-35174 on the back surface. A backcoat layer can be provided.

[Protective layer]
In the lithographic printing plate precursor according to the invention, a protective layer (overcoat layer) is preferably provided on the image recording layer. In addition to the function of suppressing the image formation inhibition reaction by blocking oxygen, the protective layer has a function of preventing scratches in the image recording layer and preventing ablation during high-illuminance laser exposure.

The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729. As the low oxygen permeability polymer used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used, and two or more types can be mixed and used as necessary. it can. Specific examples include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble cellulose derivatives, poly (meth) acrylonitrile, and the like.
As the modified polyvinyl alcohol, acid-modified polyvinyl alcohol having a carboxy group or a sulfo group is preferably used. Specifically, modified polyvinyl alcohols described in JP-A-2005-250216 and JP-A-2006-259137 are suitable.

Further, in order to enhance the oxygen barrier property, the protective layer preferably contains an inorganic layered compound such as natural mica and synthetic mica as described in JP-A-2005-119273.
Further, the protective layer may contain known additives such as a plasticizer for imparting flexibility, a surfactant for improving coating properties, and inorganic fine particles for controlling surface slipperiness. Further, the protective layer can contain the sensitizer described in the description of the image recording layer.

  For the protective layer, adhesion to the image area and scratch resistance are also extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on a new oil-based polymer 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 Japanese Patent Publication No. 54-12215 and British Patent No. 1303578, 20 to 60 mass of an acrylic emulsion or a water-insoluble vinylpyrrolidone-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 the composition on a polymer layer. Any of these known techniques can be applied to the protective layer in the present invention. Such a coating method for the protective layer is described in detail in, for example, US Pat. No. 3,458,311 and JP-A-55-49729.

The protective layer is applied by a known method. The coating amount of the protective layer, the coating amount after drying is preferably in the range of 0.01 to 10 g / ^{m 2,} more preferably in the range of 0.02 to 3 g / ^{m 2,} and most preferably 0. in the range of 02~1g / ^{m 2.}

[Plate making method]
The lithographic printing plate precursor according to the present invention is developed in the development process after exposure and then subjected to printing, or is developed on-machine by supplying printing ink and fountain solution without going through the development process. Can be used for printing. Hereinafter, the plate making method of the present invention will be described in detail.

〔exposure〕
In the present invention, a laser is preferable as a light source used for imagewise exposure. The laser used in the present invention is preferably a solid laser that emits infrared light having a wavelength of 760 to 1200 nm.
The output of the infrared laser is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is preferably 10 to 300 mJ / cm ² . A multi-beam laser device is preferably used to shorten the exposure time.

[Development processing]
The development processing of the lithographic printing plate precursor according to the invention can be performed by a known method. A known developer composed of an aqueous solution containing a component selected from a surfactant, an organic solvent, an alkali agent, a water-soluble polymer compound, a preservative, a chelate compound, an antifoaming agent, an organic acid, an inorganic acid, an inorganic salt, and the like. Used. It is preferable to use an automatic processor.
In the present invention, the lithographic printing plate after the development treatment can optionally be subsequently washed with water, dried and desensitized. In the desensitizing treatment, a known desensitizing solution can be used.

  The lithographic printing plate obtained by carrying out the above development processing is placed on an offset printing machine and used for printing a large number of sheets.

[On-machine development]
The exposed lithographic printing plate precursor is mounted on a plate cylinder of a printing press. In the case of a printing press equipped with a laser exposure device, imagewise exposure is performed after a lithographic printing plate precursor is mounted on the plate cylinder of the printing press.

  After the lithographic printing plate precursor is exposed imagewise with an infrared laser or the like, printing is performed by supplying printing ink and fountain solution without going through a development process such as a wet development process, and the like in the exposed part of the image recording layer. The image recording layer cured by exposure forms a printing ink receiving portion having an oleophilic surface. On the other hand, in the unexposed area, the uncured image recording layer is removed by dissolution or dispersion by the supplied dampening water and / or printing ink, and a hydrophilic surface is exposed in that area. As a result, the fountain solution adheres to the exposed hydrophilic surface, and the printing ink is deposited on the image recording layer in the exposed area and printing is started.

Here, the fountain solution or the printing ink may be supplied to the printing plate first, but the printing ink is first used in order to prevent the fountain solution from being contaminated by the removed components of the image recording layer. Is preferably supplied. As the fountain solution and printing ink, normal lithographic fountain solution and printing ink are used.
In this way, the lithographic printing plate precursor is developed on an offset printing machine and used as it is for printing a large number of sheets.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. The molecular weight of the polymer compound is a mass average molecular weight, and the ratio of repeating units is a molar ratio.

[Synthesis example of polyvalent isocyanate adduct solution (NCO-1 to 8) having an initiator site]

(Synthesis Example 1: Synthesis of NCO-1)
0.7 g of the following sulfonium compound (A-1-6) is added to 9.6 g of a trimethylolpropane and xylylene diisocyanate adduct 50 mass% ethyl acetate solution (Mitsui Chemicals Polyurethanes, Takenate D-110N). After adding 40 mg of stannous octylate (Stannoc, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) in a water bath, the mixture was stirred for 1 hour. Subsequently, it stirred at 70 degreeC for 3 hours. In this way, a solution (NCO-1) of a polyvalent isocyanate adduct having a sulfonium salt moiety was obtained.

(Synthesis Examples 2 to 8: Synthesis of NCO-2 to 8)
A solution of a polyvalent isocyanate adduct (NCO-2 to 8) having an initiator site was prepared in the same manner as in Synthesis Example 1 except that the sulfonium compound was changed to the compound shown in Table 1 below in Synthesis Example 1. Obtained.

[Synthesis example of polymer fine particles (microgel)]

(Synthesis of microgel (P-1))
As an oil phase component, 10 g of a polyisocyanate adduct (NCO-1) solution having a sulfonium salt moiety, 3.15 g of pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., SR444), and pionine A-41C ( 0.1 g of Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of Kuraray Poval PVA205 (polyvinyl alcohol manufactured by Kuraray Co., Ltd.) was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12,000 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 50 ° C. for 3 hours. The solid content concentration of the microgel solution thus obtained was diluted with distilled water so as to be 15% by mass, and this was designated as microgel (P-1). When the average particle size of the microgel was measured by a light scattering method, the average particle size was 0.2 μm.

(Synthesis of microgels (P-2) to (P-8))
In the synthesis of the microgel (P-1), the solution of the polyisocyanate adduct having a sulfonium salt moiety was changed to a polyisocyanate adduct solution as shown in Table 1 below. Microgels (P-2) to (P-8) were obtained by the same method as in the synthesis of 1).

(Synthesis of microgel (P-9))
In the synthesis of the microgel (P-1), the microgel (P-9) was prepared by the same method as the synthesis of the microgel (P-1) except that the solution of the polyvalent isocyanate adduct having a sulfonium salt moiety was not added. Obtained.

(Production of polymer fine particle aqueous dispersion (P-10))
A 1000 ml four-necked flask was equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser, and nitrogen gas was introduced to perform deoxygenation, while polyethylene glycol methyl ether methacrylate (average of PEGMA ethylene glycol) The repeating unit was 50) 9 g, distilled water 200 g and n-propanol 200 g were added and heated until the internal temperature reached 70 ° C. Next, a mixture of 1 g of the following carboxylic acid compound (A-3-1), 90 g of methyl methacrylate (MMA) and 0.8 g of 2,2′-azobisisobutyronitrile was added dropwise over 1 hour. After completion of the dropwise addition, the reaction was continued for 5 hours, and then 0.4 g of 2,2′-azobisisobutyronitrile was added to raise the internal temperature to 80 ° C. Subsequently, 0.5 g of 2,2′-azobisisobutyronitrile was added over 6 hours. Polymerization has progressed to 98% or more at the stage of reaction for a total of 20 hours, and a polymer fine particle aqueous dispersion (P-10) having a mass ratio of PEGMA / A-3-1 / MMA = 9/1/90 is obtained. Obtained. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 150 nm.

(Production of polymer fine particle aqueous dispersion (P-11))
A 1000 ml four-necked flask was equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser, and nitrogen gas was introduced to perform deoxygenation, while polyethylene glycol methyl ether methacrylate (average of PEGMA ethylene glycol) The repeating unit was 50) 9 g, distilled water 200 g and n-propanol 200 g were added and heated until the internal temperature reached 70 ° C. Next, a mixture of 1 g of the following carboxylic acid compound (A-3-2), 10 g of styrene (St), 80 g of acrylonitrile (An) and 0.8 g of 2,2′-azobisisobutyronitrile previously mixed for 1 hour It was dripped over. After completion of the dropwise addition, the reaction was continued for 5 hours, and then 0.4 g of 2,2′-azobisisobutyronitrile was added to raise the internal temperature to 80 ° C. Subsequently, 0.5 g of 2,2′-azobisisobutyronitrile was added over 6 hours. Polymerization proceeds at 98% or more at the stage of reaction for a total of 20 hours, and the polymer fine particle aqueous dispersion (PMA / A-3-2 / St / An = 9/1/10/80 by mass ratio (P -11) was obtained. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 150 nm.

(Production of polymer fine particle aqueous dispersion (P-12))
A 1000 ml four-necked flask was equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser, and nitrogen gas was introduced to perform deoxygenation, while polyethylene glycol methyl ether methacrylate (average of PEGMA ethylene glycol) The repeating unit was 50) 9 g, distilled water 200 g and n-propanol 200 g were added and heated until the internal temperature reached 70 ° C. Next, a premixed mixture of 91 g of methyl methacrylate (MMA) and 0.8 g of 2,2′-azobisisobutyronitrile was added dropwise over 1 hour. After completion of the dropwise addition, the reaction was continued for 5 hours, and then 0.4 g of 2,2′-azobisisobutyronitrile was added to raise the internal temperature to 80 ° C. Subsequently, 0.5 g of 2,2′-azobisisobutyronitrile was added over 6 hours. Polymerization progressed 98% or more at the stage of reaction for a total of 20 hours, and a polymer fine particle aqueous dispersion (P-12) having a mass ratio of PEGMA / MMA = 9/91 was obtained. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 150 nm.

(Production of polymer fine particle aqueous dispersion (P-13))
A 1000 ml four-necked flask was equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser, and nitrogen gas was introduced to perform deoxygenation, while polyethylene glycol methyl ether methacrylate (average of PEGMA ethylene glycol) The repeating unit was 50) 10 g, distilled water 200 g and n-propanol 200 g were added and heated until the internal temperature reached 70 ° C. Next, a premixed mixture of 10 g of styrene (St), 80 g of acrylonitrile (An) and 0.8 g of 2,2′-azobisisobutyronitrile was added dropwise over 1 hour. After completion of the dropwise addition, the reaction was continued for 5 hours, and then 0.4 g of 2,2′-azobisisobutyronitrile was added to raise the internal temperature to 80 ° C. Subsequently, 0.5 g of 2,2′-azobisisobutyronitrile was added over 6 hours. Polymerization proceeded at 98% or more at the stage of reaction for a total of 20 hours, and a polymer fine particle aqueous dispersion (P-13) having a mass ratio of PEGMA / St / An = 10/10/80 was obtained. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 150 nm.

  [Examples 1 to 11] Planographic printing plate precursor for alkali development

1. Preparation of support (1) In order to remove rolling oil on the surface of an aluminum plate (material JIS A 1050) having a thickness of 0.3 mm, degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution. After that, the aluminum surface was grained using ^three bundle-planted nylon brushes having a bristle diameter of 0.3 mm 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 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. At this time, the etching amount of the grained surface 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 nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Subsequently, nitric acid electrolysis was performed with an aqueous solution of 0.5% by mass of 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.
Next, the plate was provided with a direct current anodic oxide film having a current density of 15 A / dm ² and a current density of 15 g / m ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolytic solution, followed by washing with water. It dried and produced the support body (1). The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

2. Next, the following undercoat layer coating solution was applied onto the support (1) with a wire bar and dried at 100 ° C. for 10 seconds. The coating amount was 10 mg / m ² .

-Undercoat layer coating solution-
-Polymer compound A having the following structure: 0.05 g
・ Methanol 27g
・ Ion exchange water 3g

3. Application of Image Recording Layer An image recording layer coating solution having the following composition was prepared and applied onto the undercoat layer using a wire bar so that the coating amount after drying was 0.9 g / m ^2. The image recording layer was formed by drying at 115 ° C. for 34 seconds with a photographic drying apparatus.

-Coating solution for image recording layer-
・ Polymer fine particles (described in Table 3) 4.568 g
Infrared absorbing dye (IR pigment) (described in Table 3) 0.038 g
・ Radical polymerization initiator A (S-1 having the following structure) 0.030 g
-Radical polymerization initiator B (I-1 having the following structure) 0.047 g
・ Mercapto compound (SH-1 having the following structure) 0.015 g
-Sensitization aid (T-1 having the following structure) 0.081 g
Addition polymerizable compound (M-1 having the following structure) 0.428 g
-Binder polymer A (B-1 having the following structure) 0.311 g
-Binder polymer B (B-2 having the following structure) 0.250 g
・ Binder polymer C (B-3 having the following structure) 0.062 g
-Polymerization inhibitor (Q-1 having the following structure) 0.0012 g
-Copper phthalocyanine pigment dispersion 0.159g
[Copper phthalocyanine pigment: 15 parts by weight, allyl methacrylate /
Methacrylic acid (80/20) copolymer: 10 parts by mass, cyclohexanone /
Methoxypropyl acetate / 1-methoxy-2-propanol = 15 parts by mass / 20 parts by mass / 40 parts by mass]
・ Fluorine surfactant 0.0081g
(Megafuck F-780-F Dainippon Ink and Chemicals,
Methyl isobutyl ketone (MIBK) 30% by mass solution)
・ Methyl ethyl ketone 5.886g
・ Methanol 2.733g
・ 1-methoxy-2-propanol 5.886 g

4). Coating of protective layer <Lower protective layer>
On the surface of the image recording layer, synthetic mica (Somasif MEB-3L, 3.2 mass% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.), polyvinyl alcohol (Goselan CKS-50: saponification degree 99 mol%, polymerization degree 300, Aqueous solution of sulfonic acid-modified polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Surfactant A (manufactured by Nippon Emulsion Co., Ltd., Emalex 710) and surfactant B (Adeka Pluronic P-84: manufactured by Asahi Denka Kogyo Co., Ltd.) Protective layer coating solution) was applied with a wire bar, and dried at 125 ° C. for 30 seconds with a hot-air dryer.
The content ratio of synthetic mica (solid content) / polyvinyl alcohol / surfactant A / surfactant B in the mixed aqueous solution (coating liquid for protective layer) was 7.5 / 89/2 / 1.5 (mass). The coating amount (the coating amount after drying) was 0.5 g / m ² .

<Upper protective layer>
On the surface of the lower protective layer, organic filler (Art Pearl J-7P, manufactured by Negami Kogyo Co., Ltd.), synthetic mica (Somasif MEB-3L, 3.2 mass% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.), polyvinyl alcohol (L-3266: saponification degree 87 mol%, polymerization degree 300, sulfonic acid-modified polyvinyl alcohol, Nippon Synthetic Chemical Industry Co., Ltd.), thickener (Serogen FS-B, Daiichi Kogyo Seiyaku Co., Ltd.), the above A mixed aqueous solution (protective layer coating solution) of polymer compound A and a surfactant (manufactured by Nippon Emulsion Co., Ltd.) is applied with a wire bar and dried at 125 ° C. for 30 seconds in a hot air dryer. It was.
The content ratio of the organic filler / synthetic mica (solid content) / polyvinyl alcohol / thickener / polymer compound A / surfactant in the mixed aqueous solution (protective layer coating solution) is 4.7 / 2.8. /67.4/18.6/2.3/4.2 (mass%), and the coating amount (the coating amount after drying) was 1.8 g / m ² .
In this way, lithographic printing plate precursors of Examples 1 to 11 were obtained.

[Comparative Examples 1-5]
In Example 1, lithographic printing plate precursors of Comparative Examples 1 to 5 were obtained in the same manner as in Example 1 except that the polymer fine particles and the infrared absorbing dye were changed as shown in Table 3 below.

[Comparative Example 6]
In Example 1, the polymer fine particle (P-1) was changed to (P-9), and 0.095 g of the polymerization initiator (A-1-6) (the polymerization start contained in the polymer fine particle in Example 1) A lithographic printing plate of Comparative Example 6 was obtained in the same manner as in Example 1 except that it was added in the same manner as in Example 1.

[Evaluation of planographic printing plate precursor]
(1) Sensitivity evaluation The obtained lithographic printing plate precursor was set at a log E of 0.00 with a resolution of 175 lpi, an outer drum rotation speed of 150 rpm, and an output of 0 to 8 W using a Trendsetter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser. The exposure was changed by 15 steps. The exposure was performed under conditions of 25 ° C. and 50% RH. After the exposure, development was performed at 30 ° C. for 12 seconds using LP-1310News manufactured by FUJIFILM Corporation. The developer used was a 1: 4 water diluted water of DH-N manufactured by Fuji Film Co., Ltd., and the 1: 1 water diluted solution of GN-2K manufactured by Fuji Film Co., Ltd. was used as the finisher.
The density of the image area of the lithographic printing plate obtained by development was measured using a Macbeth reflection densitometer RD-918 and the cyan density using a red filter equipped in the densitometer. The reciprocal of the exposure necessary to obtain a measured density of 0.8 was used as an index of sensitivity. In the evaluation results, the sensitivity of the lithographic printing plate obtained in Comparative Example 1 was 100, and the sensitivity of other lithographic printing plates was a relative evaluation thereof. The larger the value, the better the sensitivity. The results are shown in Table 3.

(2) Printing durability evaluation and dirt evaluation An 80% flat screen image with a resolution of 175 lpi was output to the produced lithographic printing plate precursor using a water-cooled 40 W infrared semiconductor laser and a 175 lpi 80% flat screen image with an output of 8 W and an external drum. The exposure was performed at a rotation speed of 206 rpm and a plate surface energy of 100 mJ / cm ² . After the exposure, the protective layer was removed by rinsing with tap water, and then developed by the same method as in (1) Sensitivity evaluation development step. Then, the obtained lithographic printing plate was printed using a printing press Lithron manufactured by Komori Corporation, and the number of printed images (finished number of sheets) was used as an index of printing durability. The printing stain was printed on 1000 sheets, and the print stain on the non-image area was visually evaluated. The results are shown in Table 3.

(3) Evaluation of storage stability The lithographic printing plate precursor was subjected to forced aging at 60 ° C. and 75% Rh for 4 days, and then a lithographic printing plate was prepared in the same manner as described above, and printed in the same manner as not aging. .

  As is clear from Table 3, the lithographic printing plate precursors (Examples 1 to 11) using the polymer fine particles of the present invention are lithographic printing plate precursors containing no polymer fine particles (Comparative Example 1) and polymers not containing an initiator. Compared to the lithographic printing plate precursor using the fine particles (Comparative Examples 2 to 5), improvements in sensitivity, stain resistance and printing durability were observed. Furthermore, the lithographic printing plate precursors of Examples 1 to 11 are more stable than the lithographic printing plate precursor using ammonium (Comparative Example 5) in addition to sensitivity, stain resistance and printing durability. There is an improvement in the subsequent stain resistance. In addition, an improvement in storage stability (stain resistance after forced aging) is observed as compared with the case where another initiator is added (Comparative Example 6).

[Examples 12 to 22] On-press development type lithographic printing plate precursor (1) Preparation of support (2) In order to ensure the hydrophilicity of the non-image area, 2.5% by mass of the support (1) was 3% by mass. A silicate treatment was performed at 60 ° C. for 10 seconds using an aqueous sodium silicate solution, and then washed with water to obtain a support (2). The adhesion amount of Si was 10 mg / m ² .

(2) Formation of undercoat layer Next, the following undercoat layer coating solution (1) is applied onto the support (2) so that the dry coating amount is 20 mg / m ² , and used in the following experiments. A support having a layer was prepared.

<Coating liquid for undercoat layer (1)>
-Undercoat layer compound (1) having the following structure: 0.18 g
・ Hydroxyethyliminodiacetic acid 0.10g
・ Methanol 55.24g
・ Water 6.15g

(3) Formation of image recording layer The image recording layer coating solution (1) having the following composition was bar-coated on the undercoat layer formed as described above, and then oven-dried at 100 ° C for 60 seconds to obtain a dry coating amount. An image recording layer of 1.0 g / m ² was formed.
The image recording layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and polymer fine particle solution immediately before coating.

<Photosensitive solution (1)>
-Binder polymer (1) [the following structure] 0.240 g
Infrared absorbing dye (IR dye) [Type: listed in Table 4] 0.030 g
-Radical polymerization initiator (1) [the following structure] 0.081 g
-Radical polymerizable compound Tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.192 g
・ Low molecular weight hydrophilic compound Tris (2-hydroxyethyl) isocyanurate 0.062g
・ Low molecular weight hydrophilic compound (1) [the following structure] 0.050 g
-Sensitizing agent Phosphonium compound (1) [the following structure] 0.055 g
・ Sensitizer Benzyl-dimethyl-octylammonium ・ PF ₆ salt 0.018g
-Sensitizing agent Ammonium group-containing polymer [the following structure, reduced specific viscosity 44 ml / g] 0.035 g
・ Fluorosurfactant (1) [The following structure] 0.008g
・ 2-butanone 1.091g
・ 1-methoxy-2-propanol 8.609g

<Polymer fine particle liquid>
・ Polymer fine particles [Type: described in Table 4] 2.640 g
・ Distilled water 2.425g

  Binder polymer (1), infrared absorbing dye (1), radical polymerization initiator (1), phosphonium compound (1), low molecular weight hydrophilic compound (1), ammonium group-containing polymer, and fluorine-based interface used in the above formulation The structure of the active agent (1) is as shown below.

(4) Formation of Protective Layer After the bar coating of the protective layer coating liquid (1) having the following composition was applied on the image recording layer, it was oven-dried at 120 ° C. for 60 seconds, and the dry coating amount was 0.15 g / m. ² protective layers were formed to obtain planographic printing plate precursors of Examples 12-22.

<Coating liquid for protective layer (1)>
・ Inorganic layered compound dispersion (1) 1.5 g
-Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd. CKS50, sulfonic acid modification,
Saponification degree 99 mol% or more, polymerization degree 300) 6% by mass aqueous solution 0.55 g
・ Polyvinyl alcohol (PVA-405 manufactured by Kuraray Co., Ltd.)
Degree of saponification 81.5 mol%, degree of polymerization 500) 6% by weight aqueous solution 0.03 g
・ Nippon Emulsion Co., Ltd. surfactant (Emalex 710) 1% by weight aqueous solution 0.86g
・ Ion-exchanged water 6.0g

(Preparation of inorganic layered compound dispersion (1))
6.4 g of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co., Ltd.) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed particles was 100 or more.

[Comparative Examples 7 to 11]
In Example 12, lithographic printing plate precursors of Comparative Examples 7 to 11 were obtained in the same manner as in Example 12 except that the polymer fine particles were changed as shown in Table 4 below.

[Comparative Example 12]
In Example 16, the polymer fine particle (P-5) was changed to (P-9), and 0.056 g of the polymerization initiator (A-2-5) (the polymerization start contained in the polymer fine particle in Example 16) A lithographic printing plate precursor of Comparative Example 12 was obtained in the same manner as in Example 16 except that the same amount was added).

[Comparative Example 13]
In Example 12, the polymer fine particle (P-1) was changed to (P-9), and 0.056 g of the polymerization initiator (A-1-6) (the polymerization start contained in the polymer fine particle in Example 1) A lithographic printing plate precursor of Comparative Example 13 was obtained in the same manner as in Example 12 except that the same amount was added.

[Evaluation of planographic printing plate precursor]

(1) On-machine developability The obtained lithographic printing plate precursor was subjected to an external drum rotation speed of 1000 rpm, a laser output of 70%, and a resolution of 2400 dpi on a Fujifilm Corporation Luxel PLASETTER T-6000III equipped with an infrared semiconductor laser. Exposed. The exposure image includes a thin line chart.
The obtained exposed original plate was attached to a plate cylinder of a printing machine LITHRONE 26 manufactured by Komori Corporation without developing. Equality-2 (manufactured by FUJIFILM Corporation) / tap water = 2/98 (volume ratio) dampening water and Values-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.) After dampening water and ink were supplied by the standard automatic printing start method of LITHRONE 26 and developed on the machine, 100 sheets were printed on Tokuhishi Art (76.5 kg) paper at a printing speed of 10,000 sheets per hour.
The number of print sheets required until the on-press development on the printing press of the unexposed portion of the image recording layer was completed and the ink was not transferred to the non-image portion was measured as on-press developability. The results are shown in Table 4.

(2) Fine line reproducibility Generally, in the case of a negative lithographic printing plate precursor, when the exposure amount is small, the degree of cure of the image recording layer (photosensitive layer) is low, and when the amount of exposure is large, the degree of cure is high. When the image recording layer has a too low degree of curing, the printing durability of the lithographic printing plate becomes low, and the reproducibility of small dots and fine lines becomes poor. On the other hand, when the degree of cure of the image recording layer is high, the printing durability is high, and the reproducibility of small dots and fine lines is good.
In this example, as shown below, the lithographic printing plate precursor obtained above was evaluated for printing durability and fine line reproducibility under the same exposure conditions described above, thereby improving the sensitivity of the lithographic printing plate precursor. It was used as an index. That is, it can be said that the sensitivity of the lithographic printing plate precursor is higher as the number of printed sheets in printing durability is higher and the fine line width in fine line reproducibility is thinner.
Specifically, after 100 sheets were printed as described above and it was confirmed that a printed matter having no ink stains in the non-image area was obtained, 500 sheets were continuously printed. A thin line chart (10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 60, 80, 100, and 200 μm fine line exposed charts) of a total of 600 printed sheets with a 25X magnifier The fine line reproducibility was evaluated based on the fine line width that was observed and reproduced with ink without interruption. The level that can be reproduced up to 10 μm is indicated by ◯, and the level that can be reproduced up to 16 μm is indicated by Δ. The results are shown in Table 4.

(3) Dirtiness (storage stability)
In an unexposed state, a lithographic printing plate precursor subjected to forced aging (temperature: 45 ° C., humidity: 75% stored for 3 days) was exposed and developed under the same conditions as in the on-machine development evaluation, and 100 sheets were printed. The printed matter at that time was visually evaluated for non-image area contamination. The storage stability can be evaluated by comparing with the case where forced aging was not performed. The results are shown in Table 4.

(4) Printing durability After the above-described evaluation of on-press developability, the printing was further continued. As the number of printed sheets was increased, the image recording layer was gradually worn out, so that the ink density on the printed material decreased. Printing durability was evaluated using the number of printed copies when the value measured by the Gretag densitometer for the 50% halftone dot area ratio of the FM screen in the printed material was 5% lower than the measured value for the 100th printed sheet. . The results are shown in Table 4.

  As is clear from Table 4, the lithographic printing plate precursors (Examples 12 to 22) using the polymer fine particles of the present invention do not contain a lithographic printing plate precursor containing no polymer fine particles (Comparative Example 7), an initiator and the like. Compared with the lithographic printing plate precursor using the fine polymer particles (Comparative Examples 8 to 10), improvements in sensitivity, stain resistance and printing durability were observed. Furthermore, the lithographic printing plate precursors of Examples 12 to 22 are more stable than the lithographic printing plate precursor using ammonium (Comparative Example 11), in addition to sensitivity, stain resistance and printing durability. There is an improvement in the subsequent stain resistance. In addition, the lithographic printing plate precursor of Example 16 has storage stability (resistance after forced aging) in addition to sensitivity, stain resistance and printing durability even when a carboxylic acid compound is added separately (Comparative Example 12). There is an improvement in soiling). Further, the lithographic printing plate precursor of Example 12 shows an improvement in storage stability (stain resistance after forced aging) as compared with the case where another initiator is added (Comparative Example 13).

Claims (6)

A lithographic printing plate precursor having a polymerizable composition containing a combination of (A) fine polymer particles, (B) a radical polymerizable compound, and (C) an infrared absorbing dye on a hydrophilic support in an image recording layer. (A) The polymer fine particles are at least one selected from a polymerization initiator group consisting of a sulfonium salt, an iodonium salt, a diazonium salt, an azinium salt, an oxime compound and a triazine compound, and a compound represented by the following general formula (1). A lithographic printing plate precursor comprising fine polymer particles covalently linked to a compound.

In general formula (1), A represents an aromatic hydrocarbon group or a heterocyclic group. X ¹ represents a divalent linking group selected from —O—, —S—, and —N (R ³ ) —. R ³ represents a hydrogen atom or an alkyl group which may have a substituent. R ¹ and R ² each independently represents a hydrogen atom or an alkyl group.   The polymer fine particles are represented by a polymerization initiator group having a polyvalent isocyanate compound, a sulfonium salt, an iodonium salt, a diazonium salt, an azinium salt, an oxime compound and a triazine compound having a hydroxy group or an amino group, and the general formula (1). The lithographic printing plate precursor as claimed in claim 1, wherein the lithographic printing plate precursor is a fine polymer particle obtained by an addition reaction with at least one selected from the following compounds.   2. The lithographic printing plate precursor according to claim 1, wherein the polymer fine particles are polymer fine particles obtained by radical polymerization of a compound represented by the general formula (1) having a radical polymerizable group. The lithographic printing plate precursor as claimed in any one of claims 1 to 3, wherein the infrared absorbing dye is a cyanine dye represented by the following general formula (2).

In the formula, Z ¹ and Z ² each independently represent an aromatic ring or a heteroaromatic ring which may have a substituent. R ³ and R ⁴ each independently represent a hydrocarbon group having 20 or less carbon atoms which may have a substituent, and R ⁹ and R ¹⁰ may each independently have a hydrogen atom or a substituent. Represents an alkoxy group. Za ⁻ represents a counter anion present when charge neutralization is required.   The on-press development type lithographic printing plate precursor according to any one of claims 1 to 4, wherein an unexposed portion of the image recording layer can be removed by dampening water and / or printing ink.   An on-press development type lithographic printing plate precursor according to claim 5 is image-exposed with an infrared laser and then attached to a printing machine cylinder, and the image recording layer unexposed portion is removed with fountain solution and printing ink. Method.