JP2007086219A - Infrared-sensitive planographic printing precursor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared-sensitive positive planographic printing plate precursor in which a recording layer is free of abrasion due to transport and faulty adhesion during storage even when such precursors are stacked without using a slip sheet, and which is suitably used even in an exposure apparatus equipped with an automatic feed unit (autoloader). <P>SOLUTION: The infrared-sensitive planographic printing plate precursor has, on one surface of a support, a recording layer containing a water-insoluble and alkali-soluble resin, an infrared absorber and a long-chain alkyl group-containing polymer, and capable of forming an image by infrared irradiation, and has a back coating layer containing an organic polymer and having a thickness of ≥0.3 μm on the other surface of the support. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an infrared-sensitive lithographic printing plate precursor, and more particularly, to an infrared-sensitive lithographic printing plate precursor in which damage to the photosensitive layer during lamination is suppressed.

  In recent years, laser development has been remarkable, and in particular, solid lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared are easily available in high output and small size. Particularly in the field of lithographic printing, these lasers are very useful as an exposure light source for making a plate directly from digital data such as a computer.

  The recording layer of a positive lithographic printing plate precursor for direct plate making using such an infrared laser has an alkali-soluble resin and an infrared absorber that absorbs light and generates heat as essential components. In the unexposed area (image area), it acts as a dissolution inhibitor that substantially reduces the solubility of the alkali-soluble resin by interaction with the alkali-soluble resin. In the exposed area (non-image area), infrared rays are generated by the generated heat. The interaction between the absorbent and the alkali-soluble resin is weakened and dissolved in an alkali developer to form an image. However, this positive type lithographic printing plate precursor has insufficient mechanical strength of the recording layer. When the plate surface and various members come into strong contact during manufacturing, transportation, and handling of the printing plate, defects occur on the plate surface, and after development. There was a problem that the image part of the image was missing.

  In order to reduce such problems, lithographic printing plate precursors are generally packaged with an interleaf (interleaf) between plates. However, since this slip sheet has problems such as 1) cost increase and 2) discarding of the slip sheet, “reduction of slip sheet” without using the slip sheet is desired. In recent years, with the spread of the CTP system, there has been an increase in the attachment of an automatic plate material supply device (autoloader) to the exposure apparatus. In order to avoid problems such as scratches caused by rubbing when removing interleaving paper even if there is a paper removal mechanism, there is a growing demand for the elimination of interleaving paper.

As a technique for reducing the slip sheet, it has been known to devise a technique for reducing mechanical damage to the photosensitive layer caused by contact between the photosensitive layer and the back surface of the support on the back surface of the support.
For example, a recording material for offset printing having a radiation-sensitive layer and an organic polymer-containing backcoat layer, by providing a back coating containing a pigment such as silica gel in an organic polymer having a glass transition temperature of at least 35 ° C. It is described that it is possible to stack without interleaving paper (Patent Document 1). However, when inorganic pigments such as silica gel are included in the backcoat layer, the inorganic pigment has a high hardness when transported in a stacked package without using interleaving paper. There is a problem that it is easy to stick.

  Further, a technique has been proposed in which a mat by electrostatic spraying is provided on the surface opposite to the photosensitive layer (see, for example, Patent Document 2), and it is described here that the sheets can be stacked without interleaving paper. However, according to this configuration, when stacked and stored without interleaving paper, adhesion between the plates may occur particularly in a high humidity environment such as summer.

Further, on the surface opposite to the photosensitive layer, at least one resin selected from the group consisting of a saturated copolymerized polyester resin, a phenoxy resin, a polyvinyl acetal resin, and a vinylidene chloride copolymer resin having a glass transition temperature of 60 ° C. or higher. A photosensitive lithographic printing plate characterized in that a backcoat layer is provided (see, for example, Patent Document 3), and a rough surface backcoat layer is provided on the surface opposite to the photosensitive layer. There has been proposed a photosensitive lithographic printing plate (see, for example, Patent Document 4).
However, a backcoat layer made of an organic polymer such as polyester has a structure in which the photosensitive layer and the back surface are pressed against each other when an autoloader that automatically supplies a plate material to a laser exposure machine is used without interleaf. It was found that the layer was easily scratched by rubbing. In addition, even when a rough backcoat layer is provided on the surface opposite to the photosensitive layer, when the photosensitive layer is laminated without interleaf and the photosensitive layer is in contact with the back surface of the support, sufficient mechanical strength is not always obtained. It was not obtained and it was found that the photosensitive layer was easily damaged.
JP 2002-46363 A JP 2003-63162 A Japanese Patent Laid-Open No. 2005-62456 JP 2002-254843 A

  The present invention has been made in view of the above problems, and even when laminated without using interleaving paper, scratches due to transportation, etc. and adhesive failure during storage do not occur in the recording layer, and It is an object of the present invention to provide an infrared-sensitive positive lithographic printing plate precursor that is also suitably used in an exposure apparatus equipped with an automatic supply device (autoloader).

As a result of intensive studies, the present inventor has found that the above-mentioned problems can be solved by the following infrared-sensitive lithographic printing plate precursor (hereinafter sometimes simply referred to as “lithographic printing plate precursor”), The present invention has been completed.
That is, one embodiment of the lithographic printing plate precursor according to the present invention comprises a water-insoluble and alkali-soluble resin, an infrared absorber, and a long-chain alkyl group-containing polymer on one side of a support, and forms an image by infrared irradiation. And a backcoat layer containing an organic polymer and having a thickness of 0.3 μm or more on the surface opposite to the surface having the recording layer of the support. A lithographic printing plate precursor.
In another embodiment of the lithographic printing plate precursor according to the invention, a lower layer containing a water-insoluble and alkali-soluble resin and a top layer containing a water-insoluble and alkali-soluble resin and a long-chain alkyl group-containing polymer are provided on one side of the support. Including a recording layer having a multilayer structure capable of forming an image by infrared irradiation, wherein at least one of the lower layer and the uppermost layer is a layer containing an infrared absorber, and the surface having the recording layer of the support; Is an infrared-sensitive lithographic printing plate precursor having a backcoat layer containing an organic polymer and having a thickness of 0.3 μm or more on the opposite surface.

The recording layer in the lithographic printing plate precursor according to the invention is prepared by dissolving a long-chain alkyl group-containing polymer and a polymer compound incompatible with the long-chain alkyl group-containing polymer in a coating solvent, and coating and drying on a support. Provided. Thereby, as the coating solvent is removed in the drying process at the time of recording layer formation, phase separation caused by the incompatibility inherent in them occurs between the long-chain alkyl group-containing polymer and the polymer compound, It is considered that the long-chain alkyl group-containing polymer self-aggregates in the recording layer to form fine particles, and microprotrusions made of the fine particles are formed on the surface of the recording layer. In the present invention, such microprotrusions reduce the frictional force on the surface of the recording layer, so that it is considered that stress (scratch stress) against scratches, scratches, etc. is alleviated.
Since the polymer containing a long-chain alkyl group that forms microprotrusions as described above is considered to be a relatively soft polymer, when the hardness of the member that gives scratch stress is low, the stress relaxation of the member itself is also sufficient. In the case of a member having high scratch resistance but high hardness, the limit of the stress relaxation due to the deformation of the microprojection can occur with a relatively weak force. For this reason, lithographic printing plate precursors are laminated and packaged without using protective paper (interleaf) between the plate materials (hereinafter referred to as “interleaf-free packaging” as appropriate), for example, transporting long distances If the recording layer surface and the back surface of the support having high hardness come into contact with each other, there is a concern that the recording layer surface may be damaged.
However, in the present invention, by providing a back coat layer containing an organic polymer and having a thickness of 0.3 μm or more on the back surface of the support, the hardness is lower than that of the aluminum surface without the back coat layer, and stress is reduced. It is considered that the scratch resistance and the like of the recording layer are drastically improved in combination with the effect exerted by the recording layer according to the present invention that is relaxed.

  According to the present invention, even when laminated without using a slip sheet, scratches due to transportation or the like and adhesion failure during storage do not occur in the recording layer, and an automatic feeding device (autoloader) is provided. It is possible to provide an infrared-sensitive positive lithographic printing plate precursor that is also suitably used in an exposure apparatus.

  Hereinafter, details of each element constituting the planographic printing plate precursor of the present invention will be sequentially described.

[Recording layer]
The recording layer in the present invention will be described.
The recording layer used in the lithographic printing plate precursor according to the invention is a layer capable of forming an image by infrared irradiation, and may be either a single layer or a multilayer structure. In the case of a single-layer type recording layer, it comprises a water-insoluble and alkali-soluble resin, a long-chain alkyl group-containing polymer, and an infrared absorber. In the case of a multi-layer type recording layer, by infrared irradiation including a lower layer containing a water-insoluble and alkali-soluble resin and a top layer containing a water-insoluble and alkali-soluble resin and a long-chain alkyl group-containing polymer. The recording layer has a multilayer structure capable of forming an image, and at least one of the lower layer and the uppermost layer is configured as a layer containing an infrared absorber. Hereinafter, each component contained in the recording layer in the invention will be described in order.

(Long chain alkyl group-containing polymer)
The recording layer in the present invention contains a long-chain alkyl that can be phase separated from a polymer compound (preferably water-insoluble and alkali-soluble resin) contained in the coating solution to form protrusions on the outermost surface during coating formation. It is characterized by containing a polymer.
The long-chain alkyl-containing polymer is dissolved in the coating solvent together with other polymer compounds in the coating solution, but in the drying step after coating, phase separation from other components occurs along with the removal of the solvent, and self- It has the property of agglomerating to form protrusions on the outermost surface. Therefore, the microprotrusions made of this long-chain alkyl group-containing polymer are different from conventional surface protrusions formed by adding a fine particle dispersion of inorganic particles, metal particles, and organic particles to the coating solution in terms of their manufacturing method and physical properties In particular, fine particles (microprojections) have the advantage of excellent adhesion to the polymer compound constituting the matrix.

In the present invention, the fine protrusions present on the surface of the recording layer can be easily confirmed by observing the surface of the recording layer with a microscope.
The average particle size of the fine particles forming the surface protrusion is preferably 0.05 μm to 50 μm, more preferably 0.1 μm to 20 μm, and more preferably 0.3 μm to 10 μm. If the average particle size is less than 0.05 μm, the formation of irregularities on the surface of the recording layer is insufficient, and there is a concern that the effect of improving scratch resistance cannot be obtained sufficiently. Also, if there are protrusions exceeding 50 μm, there is a concern that the resolution of the printed matter and the adhesion to the lower layer will be lowered, and particles existing in the vicinity of the surface will be easily removed by external stress, and the uniformity may be impaired. .

As a measuring method of the average particle diameter of the surface protrusions, there is generally a method of measuring the particle diameter existing on the surface by observation with an optical microscope, an electron microscope or the like and calculating the average. That is, the average particle diameter of the fine particles here is obtained by measuring a plurality of particle diameters of the fine particles composed of the long-chain alkyl group-containing polymer protruding on the surface of the recording layer and taking the average value thereof.
Further, the height of the fine protrusions existing on the surface of the recording layer is preferably 5.0 nm to 2000 nm, more preferably 10 nm to 1000 nm, and most preferably 20 nm to 800 nm.
Examples of the method for measuring the height of the surface protrusion include a method of measuring the height of the protrusion by observing a cross section with an electron microscope, and a method of measuring using an atomic force microscope (AFM). Moreover, it is preferable that a microprotrusion is soft compared with a smooth part, and this hardness can be measured using a hardness meter.

In the present invention, as an element for controlling the particle size and height of the microprotrusions made of a long chain alkyl group-containing polymer present on the surface of the recording layer, the polarity of the long chain alkyl group-containing polymer, the polarity of the polymer compound used in combination, Examples thereof include the amount of each additive, the type of coating solvent, other additives contained in the recording layer, and drying conditions (temperature, time, humidity, pressure, etc.).
For example, when the difference in polarity between the long-chain alkyl group-containing polymer and the polymer compound having no compatibility used in combination is increased, the particle size of the microprojections is increased, and the drying temperature is increased and drying is performed. By shortening the time required, the particle size of the microprojections is reduced.

As the long chain alkyl group-containing polymer in the present invention, a long chain alkyl group-containing polymer comprising a vinyl monomer having a carboxyl group in a composition ratio range of 20 to 99 mol% (hereinafter, appropriately referred to as “long chain alkyl group-containing polymer”). ").
Here, the long-chain alkyl group in the long-chain alkyl group-containing polymer refers to one having 6 or more carbon atoms, preferably 12 or more carbon atoms. More specifically, the long-chain alkyl group-containing polymer is preferably a copolymer of a monomer having a long-chain alkyl group and a vinyl monomer having a carboxy group. It is preferable to comprise in the composition ratio range of ˜99 mol%.

  The long-chain alkyl group-containing polymer is preferably made of a copolymer represented by the following general formula (I), for example.

  In general formula (I), X and X ′ each independently represent a single bond or a divalent linking group. m represents an integer of 20 <m <99, preferably an integer of 30 <m <90, and more preferably an integer of 45 <m <80. n represents an integer of 6 to 40, more preferably an integer of 12 to 30, and still more preferably an integer of 14 to 20. The bond represented by the dotted line means that a methyl group or hydrogen is present at the tip.

Specific examples of the divalent linking group represented by X and X ′ in formula (I) include a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, and a linear group having 2 to 20 carbon atoms. A branched or cyclic alkenylene group, an alkynylene group having 2 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms (monocyclic or heterocyclic ring), -OC (= O)-, -OC (= O) Ar- , -OC (= O) O - , - OC (= O) OAr -, - C (= O) NR -, - C (= O) NAr -, - SO 2 NR -, - SO 2 NAr -, - O- (alkyleneoxy, polyalkyleneoxy), -OAr- (aryleneoxy, polyaryleneoxy), -C (= O) O-, -C (= O) O-Ar-, -C (= O) Ar -, - C (= O) -, - SO 2 O -, - SO 2 OAr -, - OSO 2 -, - OSO 2 Ar -, - _{NRSO 2 -, - NArSO 2 -} , - NRC (= O) -, - NArC (= O) -, - NRC (= O) O -, - NArC (= O) O -, - OC (= O) NR -, - OC (= O) NAr -, - NAr -, - NR -, - N + RR '-, - N + RAr -, - N + ArAr' -, - S -, - SAr -, - ArS- , A heterocyclic group (the hetero atom includes, for example, at least one of nitrogen, oxygen, sulfur and the like, a 3- to 12-membered monocyclic or condensed ring), -OC (= S)-, -OC (= S) Ar-, -C (= S) O-, -C (= S) OAr-, -C (= S) OAr-, -C (= O) S-, -C (= O) SAr-, -ArC (= O)-, -ArC (= O) NR-, -ArC (= O) NAr-, -ArC (= O) O-, -ArC (= O) S-, -ArC (= S) O-, ArO -, - ArNR-, and the like. Here, R and R ′ each independently represents a hydrogen atom or a linear or branched, chain or cyclic alkyl group, alkenyl group or alkynyl group. Ar and Ar ′ each independently represents an aryl group.
The linking group may form a linking group by combining two or more of the linking groups listed here.

  Among such linking groups, arylene groups having 6 to 20 carbon atoms (monocyclic, heterocyclic), -C (= O) NR-, -C (= O) NAr-, -O- (alkyleneoxy, poly Alkyleneoxy), -OAr- (aryleneoxy, polyaryleneoxy), -C (= O) O-, -C (= O) O-Ar-, -C (= O)-, -C (= O) Ar-, -S-, -SAr-, -ArS-, -ArC (= O)-, -ArC (= O) O-, -ArO-, -ArNR- and the like are preferable, and arylene having 6 to 20 carbon atoms. Group (monocyclic, heterocyclic), -C (= O) NR-, -C (= O) NAr-, -O- (alkyleneoxy, polyalkyleneoxy), -OAr- (aryleneoxy, polyaryleneoxy) , -C (= O) O-, -C (= O) O-Ar-, -SAr-, -ArS-, ArC (= O) -, - ArC (= O) O -, - ArO -, - ArNR- are more preferable.

  The linking group may have a substituent, and examples of the substituent include a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a linear chain having 2 to 20 carbon atoms, Branched or cyclic alkenyl group, C2-C20 alkynyl group, C6-C20 aryl group, C1-C20 acyloxy group, C2-C20 alkoxycarbonyloxy group, C7-C7 20 aryloxycarbonyloxy groups, 1 to 20 carbamoyloxy groups, 1 to 20 carbonamido groups, 1 to 20 sulfonamido groups, 1 to 20 carbamoyl groups, 0 carbon atoms -20 sulfamoyl group, alkoxy group having 1 to 20 carbon atoms, aryloxy group having 6 to 20 carbon atoms, aryloxycarbonyl group having 7 to 20 carbon atoms, alkoxy having 2 to 20 carbon atoms Carbonyl group, N-acylsulfamoyl group having 1 to 20 carbon atoms, N-sulfamoylcarbamoyl group having 1 to 20 carbon atoms, alkylsulfonyl group having 1 to 20 carbon atoms, arylsulfonyl group having 6 to 20 carbon atoms , An alkoxycarbonylamino group having 2 to 20 carbon atoms, an aryloxycarbonylamino group having 7 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an imino group having 1 to 20 carbon atoms, an ammonio group having 3 to 20 carbon atoms Carboxy group, sulfo group, oxy group, mercapto group, alkylsulfinyl group having 1 to 20 carbon atoms, arylsulfinyl group having 6 to 20 carbon atoms, alkylthio group having 1 to 20 carbon atoms, arylthio group having 6 to 20 carbon atoms , A ureido group having 1 to 20 carbon atoms, a heterocyclic group having 2 to 20 carbon atoms, an acyl group having 1 to 20 carbon atoms, and a sulfamoy having 0 to 20 carbon atoms. Amino group, a silyl group having 2 to 20 carbon atoms, hydroxy group, a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom), a cyano group and a nitro group.

  The long-chain alkyl group-containing polymer is more preferably composed of, for example, an acrylic copolymer represented by the following general formula (II).

  In general formula (II), X and X ′ each independently represent a single bond or a divalent linking group. X and X ′ represented by the general formula (II) are synonymous with those represented by X and X ′ in the general formula (I), and preferred examples thereof are also the same. m represents an integer of 20 <m <99, preferably an integer of 30 <m <90, and more preferably an integer of 45 <m <80. n represents an integer of 6 to 40, more preferably an integer of 12 to 30, and still more preferably an integer of 14 to 20. The bond represented by the dotted line means that a methyl group or hydrogen is present at the tip.

  The long-chain alkyl group-containing polymer is more preferably composed of, for example, an acrylic copolymer represented by the following general formula (III).

  In general formula (III), X and X ′ each independently represent a single bond or a divalent linking group. X and X ′ represented by the general formula (III) have the same meanings as those represented by X and X ′ in the general formula (I), and preferred examples thereof are also the same. m represents an integer of 20 <m <99, preferably an integer of 30 <m <90, and more preferably an integer of 45 <m <80. n represents an integer of 6 to 40, more preferably an integer of 12 to 30, and still more preferably an integer of 14 to 20. Note that a bond represented by a dotted line means that a methyl group or hydrogen is present at the tip.

  The long-chain alkyl group-containing polymer is most preferably composed of, for example, an acrylic copolymer represented by the following general formula (IV) or general formula (V).

  In general formula (IV) and general formula (V), m represents an integer of 20 <m <99, preferably an integer of 30 <m <90, and more preferably an integer of 45 <m <80. n represents an integer of 6 to 40, more preferably an integer of 12 to 30, and still more preferably an integer of 14 to 20. The bond represented by the dotted line means that a methyl group or hydrogen is present at the tip.

  Furthermore, the long-chain alkyl group-containing polymer is most preferably an acrylic copolymer represented by the general formula (V) from the balance of scratch resistance and alkali solubility.

  The long chain alkyl group-containing polymer is a copolymer with one or more selected from the following hydrophilic monomers and other monomers, in addition to the monomer having a long chain alkyl group and the vinyl monomer having a carboxy group. Also good. In that case, the molar composition ratio of the other monomer in the copolymer is preferably 40 mol% or less, more preferably 30 mol% or less, and more preferably 25 mol% from the viewpoint of surface microprojection formation. More preferably, it is as follows.

<Hydrophilic monomer>
The monomer to be copolymerized with the monomer having a long-chain alkyl group and the vinyl monomer having a carboxy group is preferably a hydrophilic monomer from the viewpoint of solubility in an alkali developer and sensitivity.

As such a hydrophilic monomer, monomers having an acidic group listed in the following (1) to (5) are preferable in terms of solubility and sensitivity to an alkaline developer.
(1) Phenol group (-Ar-OH)
(2) Sulfonamide group (—SO ₂ NH—R)
(3) active imide group _{(-SO 2 NHCOR, -SO 2 NHSO} 2 R, -CONHSO 2 R)
(4) Sulfonic acid group (—SO ₃ H)
(5) Phosphate group (—OPO ₃ H ₂ )
In (1) to (5), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrocarbon group which may have a substituent.

  Examples of the monomer (1) having a phenol group include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, and hydroxystyrene having a phenol group.

  Examples of the monomer (2) having a sulfonamide group include compounds having at least one sulfonamide group having the above structure and one polymerizable unsaturated group in the molecule. Among these, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group and a sulfonamide group in the molecule is preferable. Examples thereof include compounds represented by the following general formulas (i) to (v).

In general formulas (i) to (v), X ¹ and X ² each independently represent —O— or —NR ⁷ —. R ¹ and R ⁴ each independently represents a hydrogen atom or —CH ₃ . R ² , R ⁵ , R ⁹ , R ¹² and R ¹⁶ are each independently an alkylene group, cycloalkylene group, arylene group or aralkylene group having 1 to 12 carbon atoms which may have a substituent. Represents. R ³ , R ⁷ and R ¹³ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group having 1 to 12 carbon atoms which may have a substituent. R ⁶ and R ¹⁷ each independently represents an alkyl group, cycloalkyl group, aryl group or aralkyl group having 1 to 12 carbon atoms which may have a substituent. R ⁸ , R ¹⁰ and R ¹⁴ each independently represents a hydrogen atom or —CH ₃ . R ¹¹ and R ¹⁵ each independently represents a single bond or a C 1-12 alkylene group, cycloalkylene group, arylene group or aralkylene group which may have a substituent. Y ¹ and Y ² each independently represent a single bond or —CO—.

  Among the compounds represented by the general formulas (i) to (v), in the lithographic printing plate precursor according to the invention, in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- ( p-Aminosulfonylphenyl) acrylamide and the like can be preferably used.

  Examples of the monomer (3) having an active imide group include compounds each having at least one active imide group represented by the structural formula and one polymerizable unsaturated group in the molecule. Among these, compounds having at least one active imide group represented by the following structural formula and one polymerizable unsaturated group in the molecule are preferable.

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

Examples of the monomer (4) having a sulfonic acid group include compounds each having one or more sulfonic acid groups and polymerizable unsaturated groups in the molecule.
Examples of the monomer (5) having a phosphate group include compounds having at least one phosphate group and one polymerizable unsaturated group in the molecule.

  Among the hydrophilic monomers, (1) a phenol group, (2) a sulfonamide group, or (3) a monomer having an active imide group is preferred, and in particular, (1) a monomer having a phenol group or (2) a sulfonamide group. However, it is most preferable from the viewpoint of sufficiently ensuring solubility in an alkaline developer, development latitude, and film strength.

<Other monomers>
Examples of other monomers copolymerizable with a monomer having a long-chain alkyl group and a vinyl monomer having a carboxy group include the compounds listed in the following (6) to (16).

(6) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(7) Methyl acrylate, ethyl acrylate, propyl acrylate, amyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoalkylate Acrylates and the like.
(8) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate, polyethylene glycol monomethacrylate, polypropylene Methacrylates such as glycol monomethacrylate.

(9) Acrylamide, methacrylamide, N-methylolacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.
(10) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and phenyl vinyl ether.
(11) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.

(12) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene.
(13) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(14) Olefins such as ethylene, propylene, isobutylene, butadiene, and isoprene.

(15) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
(16) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

  Examples of the copolymerization method of the monomer having a long chain alkyl group, the vinyl monomer having a carboxy group, the hydrophilic monomer, and the other monomers listed above include the conventionally known graft copolymerization method and block copolymerization method. Further, a random copolymerization method or the like can be used. In this copolymerization, two or more of the respective monomers can be mixed and used. In addition, when using 2 or more types of monomers which have a carboxy group, it is long chain in this invention that the sum of the molar composition ratio of those used monomers exists in the composition ratio range of 20-99 mol%. Preferred as an alkyl group-containing polymer.

  Specific examples of the long-chain alkyl group-containing polymer include the following, but are not limited thereto.

  As the long-chain alkyl group-containing polymer used in the present invention, those having a weight average molecular weight of 5,000 or more and a number average molecular weight of 1,000 or more are preferably used. More preferably, the weight average molecular weight in terms of polystyrene is 10,000 to 5,000,000, particularly preferably 10,000 to 2,000,000, still more preferably 20,000 to 1,000,000. One kind of such a polymer may be used, or two or more kinds may be used in combination.

  The amount of residual monomer in the long-chain alkyl group-containing polymer is determined when the lithographic printing plate precursor of the present invention is laminated, transfer to a protective paper (interleaf), the back of the substrate, or to a roller during the production of the lithographic printing plate precursor. From the above problems, it is preferably 10% by mass or less, and more preferably 5% by mass or less.

The recording layer is formed by mixing a long-chain alkyl group-containing polymer and each component described later as a component used in the recording layer, and applying the mixture as a recording layer coating liquid on the support. This causes phase separation between the long-chain alkyl group-containing polymer and the polymer compound contained in the recording layer component, for example, an alkali-soluble resin, which will be described later, and the long-chain alkyl group-containing polymer is self-aggregated and has a minute surface. A protrusion is formed.
Here, the addition amount of the long-chain alkyl group-containing polymer contained in the total solid content of the recording layer is preferably about 0.5 to 30% by mass, and more preferably 1 to 20% by mass. When the content of the long chain alkyl group-containing polymer is less than 0.5% by mass, the formation of irregularities is insufficient and the effect of improving the scratch resistance is not sufficiently obtained. When the content exceeds 30% by mass, the strength of the upper recording layer decreases. As a result, printing durability tends to decrease.

  In addition, as a preferable characteristic of the image recording material for sufficiently exhibiting the effects of the present invention, the contact angle of the water droplets on the surface of the recording layer after formation of the recording layer containing the long chain alkyl group-containing polymer is from 60 degrees to 140 degrees. The dynamic friction coefficient of the surface of the recording layer when a recording layer containing a long chain alkyl group-containing polymer is formed is in the range of 0.38 to 0.70. The kind and addition amount of the long chain alkyl group-containing polymer may be determined in consideration. The dynamic friction coefficient referred to here refers to a value measured in accordance with standard ASTM D1894 by placing the recording layer surface in contact with stainless steel.

(Water-insoluble and alkali-soluble resin)
The water-insoluble and alkali-soluble resin (hereinafter, appropriately referred to as alkali-soluble resin) used in the recording layer of the present invention is a homopolymer containing an acidic group in the main chain and / or side chain in the polymer, These copolymers or mixtures thereof are included. Accordingly, the recording layer in the present invention has a property of dissolving when contacted with an alkaline developer.
The alkali-soluble resin used in the present invention is not particularly limited as long as it is a conventionally known resin, but (1) phenolic hydroxyl group, (2) sulfonamide group, (3) active imide group, and (4) carvone. A polymer compound having at least one acidic group selected from acid groups in the molecule is preferable. For example, the following are exemplified, but the present invention is not limited to these.

(1) Examples of the polymer compound having a phenolic hydroxyl group include phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (m-, p Any of-or m- / p-mixing) may be used. Examples thereof include novolak resins such as mixed formaldehyde resins and pyrogallol acetone resins.

  Moreover, as an alkali-soluble resin having a phenolic hydroxyl group, a resin obtained by condensing a substituted phenol represented by the following general formula (i) and an aldehyde is also preferable.

In general formula (i), R < ¹ > and R < ² > represent a hydrogen atom, an alkyl group, and a halogen atom, respectively. As an alkyl group, it is preferable that it is a C1-C3 alkyl group, More preferably, it is a C1-C2 alkyl group. The halogen atom is any one of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, preferably a chlorine atom and a bromine atom. R ³ represents an alkyl group having 3 to 6 carbon atoms or a cycloalkyl group.

  Specific examples of the substituted phenols include isopropylphenol, t-butylphenol, t-amylphenol, hexylphenol, cyclohexylphenol, 3-methyl-4-chloro-6-tertiarybutylphenol, isopropylcresol, and t-butylcresol. , T-Amylresole. Of these, t-butylphenol and t-butylcresol are preferable.

  Examples of the aldehydes used for the condensation with the substituted phenols include aliphatic and aromatic aldehydes such as formaldehyde, acetaldehyde, acrolein, and crotonaldehyde. Of these, formaldehyde or acetaldehyde is preferable.

  Other examples of the alkali-soluble resin having a phenolic hydroxyl group include polymer compounds having a phenolic hydroxyl group in the side chain. As a polymer compound having a phenolic hydroxyl group in the side chain, a polymerizable monomer comprising a low molecular compound having at least one unsaturated bond polymerizable with the phenolic hydroxyl group is homopolymerized, or other polymerizable property is added to the monomer. Examples thereof include a polymer compound obtained by copolymerizing monomers.

  Examples of the polymerizable monomer having a phenolic hydroxyl group include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, and hydroxystyrene having a phenolic hydroxyl group. Specifically, N- (2-hydroxyphenyl) acrylamide, N- (3-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) acrylamide, N- (2-hydroxyphenyl) methacrylamide, N- (3 -Hydroxyphenyl) methacrylamide, N- (4-hydroxyphenyl) methacrylamide, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p- Hydroxyphenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (2-hydroxyphenyl) ethyl acrylate, 2- (3-hydroxyphenyl) Preferred are ethyl acrylate, 2- (4-hydroxyphenyl) ethyl acrylate, 2- (2-hydroxyphenyl) ethyl methacrylate, 2- (3-hydroxyphenyl) ethyl methacrylate, 2- (4-hydroxyphenyl) ethyl methacrylate, and the like. Can be used. Two or more kinds of resins having a phenolic hydroxyl group may be used in combination.

  Further, as the alkali-soluble resin having a phenolic hydroxyl group used in the present invention, at least a part of the phenolic hydroxyl group of the alkali-soluble resin having a phenolic hydroxyl group described in JP-A No. 11-288089 is esterified. Examples include alkali-soluble resins.

(2) Examples of the alkali-soluble resin having a sulfonamide group include polymer compounds obtained by homopolymerizing a polymerizable monomer having a sulfonamide group or copolymerizing the monomer with another polymerizable monomer. The polymerizable monomer having a sulfonamide group includes one or more sulfonamide groups —NH—SO ₂ — in which at least one hydrogen atom is bonded on a nitrogen atom and one or more polymerizable unsaturated bonds in one molecule. And a polymerizable monomer comprising a low molecular weight compound. Among them, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group, and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group is preferable.

  Specific examples of the alkali-soluble resin having a sulfonamide group include those described in JP-B-7-69605.

(3) The alkali-soluble resin having an active imide group preferably has an active imide group (—CO—NH—SO ₂ —) in the molecule, and the polymer compound includes an active imide group in one molecule. Examples thereof include a high molecular compound obtained by homopolymerizing a polymerizable monomer composed of a low molecular compound having at least one polymerizable unsaturated bond, or by copolymerizing the monomer with another polymerizable monomer.

  As specific examples of such a compound, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be suitably used.

(4) As the alkali-soluble resin having a carboxylic acid group, for example, a polymerizable monomer comprising a low molecular compound having at least one carboxylic acid group and polymerizable unsaturated group in the molecule is homopolymerized or the monomer. And polymer compounds obtained by copolymerizing other polymerizable monomers. Specific examples of the polymerizable monomer having a carboxylic acid group include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and itaconic acid. Also, monoesters of hydroxyl groups of acrylates or methacrylates having a hydroxyl group in the side chain (for example, 2-hydroxyethylethyl acrylate or methacrylate) and dibasic acids (for example, succinic acid, glutaric acid, phthalic acid, etc.) The unsaturated carboxylic acid which is is also preferable.

  Furthermore, the alkali-soluble resin of the present invention includes the polymerizable monomer having a phenolic hydroxyl group, the polymerizable monomer having a sulfonamide group, the polymerizable monomer having an active imide group, and the polymerizable monomer having a carboxylic acid group. A polymer compound obtained by polymerizing two or more of the above, or a polymer compound obtained by copolymerizing these two or more polymerizable monomers with another polymerizable monomer can be used.

  In the present invention, when the alkali-soluble resin is a copolymer of a monomer having the acidic group (phenolic hydroxyl group, sulfonamide group, active imide group, carboxylic acid group) and another polymerizable monomer, From the viewpoint of solubility, the monomer imparting alkali solubility is preferably contained in an amount of 10 mol% or more, more preferably 20 mol% or more.

Examples of the monomer component to be copolymerized with the monomer having an acidic group include the compounds listed in the following (m1) to (m11), but are not limited thereto.
(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, and glycidyl acrylate. (M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, and glycidyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.
(M5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(M6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(M7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene.
(M8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(M9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(M10) N-vinylpyrrolidone, acrylonitrile, methacrylonitrile and the like.
(M11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

  As a copolymerization method of the alkaline water-soluble polymer compound, a conventionally known graft copolymerization method, block copolymerization method, random copolymerization method, or the like can be used.

  In the present invention, when the alkali-soluble resin is a homopolymer or copolymer of a polymerizable monomer having the acidic group, the weight average molecular weight is preferably 2,000 or more. More preferably, the weight average molecular weight is 5,000 to 300,000. In the present invention, when the alkali-soluble resin is a resin such as a phenol formaldehyde resin or a cresol aldehyde resin, a weight average molecular weight of 500 to 50,000 is preferable, 700 to 20,000 is more preferable, and 1,000 to 10 is preferable. Is particularly preferred.

  When the recording layer has a multilayer structure, the alkali-soluble resin used for the uppermost layer of the recording layer causes strong hydrogen bonding in the unexposed area, and some hydrogen bonds are easily released in the exposed area. Therefore, a resin having a phenolic hydroxyl group is desirable. More preferred is a novolac resin.

  In the present invention, two or more kinds of alkali-soluble resins having different dissolution rates with respect to the alkaline aqueous solution may be mixed and used, and the mixing ratio in that case is arbitrary. As an alkali-soluble resin suitable for mixing with a resin having a phenolic hydroxyl group that is suitably used for the uppermost layer of the multi-layer type recording layer, an acrylic resin is preferred because of its low compatibility with a resin having a phenolic hydroxyl group. An acrylic resin having a sulfoamide group or a carboxylic acid group is more preferable.

  When the recording layer has a multilayer structure, the alkali-soluble resin is used for the lower layer of the recording layer, but the lower layer itself needs to exhibit high alkali solubility, particularly in the non-image area. In addition, it is necessary to develop resistance to various printing chemicals and stable printing durability in various printing conditions during printing. For this reason, it is preferable to select a resin that does not impair this property. From this viewpoint, it is preferable to select a resin having excellent solubility in an alkali developer, resistance to various printing chemicals, and physical strength. Further, as the alkali-soluble resin used for the lower layer, it is preferable to select a resin with low solvent solubility that is not dissolved by the coating solvent when the uppermost layer is applied. By selecting such a resin, undesired compatibility at the interface between the two layers is suppressed.

  From these viewpoints, the alkali-soluble resin contained in the lower layer is preferably an acrylic resin among the alkali-soluble resins. Among them, an acrylic resin having a sulfonamide group is preferable.

  In addition, from the above viewpoint, examples of the alkali-soluble resin used in the lower layer include water-insoluble and alkali-soluble polyamide resins, epoxy resins, polyvinyl acetal resins, styrene resins, and urethane resins. Among these, urethane resin and polyvinyl acetal resin are preferable.

  The water-insoluble and alkali-soluble polyurethane resin (hereinafter appropriately referred to as “polyurethane resin”) is not particularly limited as long as it is insoluble in water and soluble in an aqueous alkali solution. Those having a carboxyl group in the main chain are preferred. Specifically, a reaction product of a diisocyanate compound represented by the following general formula (ii) and at least one diol compound having a carboxyl group represented by the following general formula (iii) or general formula (iv) Polyurethane resin having a basic skeleton as a base.

In general formula (ii), R ¹ represents a divalent linking group. Examples of the divalent linking group include an aliphatic hydrocarbon, an alicyclic hydrocarbon, and an aromatic hydrocarbon, and preferably an alkylene group having 2 to 10 carbon atoms and an arylene group having 6 to 30 carbon atoms. Is mentioned. The arylene group may be a group in which two or more ring structures are linked by a single bond or a divalent organic linking group such as a methylene group, or a condensed polycyclic structure. If necessary, R ¹ may have other functional groups that do not react with isocyanate groups (for example, ester groups, urethane groups, amide groups, ureido groups, etc.).

R ¹ in the general formula (ii) may have a substituent. Examples of the substituent that can be introduced include a halogen atom (—F, —Cl, —Br, —I), an alkyl group, an alkoxyl group, an alkyl group. Substituents inert to the isocyanate group, such as ester groups and cyano groups, can be mentioned.

  Moreover, as a diisocyanate compound, it has an isocyanate group in both ends of high molecular compounds, such as the oligomer or polymer which consists of a diol compound mentioned later, for example besides the thing of the range of the compound represented by general formula (ii). A high molecular weight diisocyanate compound or the like can also be used.

In general formula (iii), R ² represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, an alkoxy group, or an aryloxy group. Here, R ² may have a substituent, and examples of the substituent that can be introduced include a cyano group, a nitro group, a halogen atom (—F, —Cl, —Br, —I), —CONH ₂ , —COOR ⁶ , —OR ⁶ , —NHCONHR ⁶ , —NHCOOR ⁶ , —NHCOR ⁶ , —OCONHR ⁶ , —CONHR ⁶ (where R ⁶ is an alkyl group having 1 to 10 carbon atoms, aralkyl having 7 to 15 carbon atoms) Group)).

Preferable R ² includes a hydrogen atom, an unsubstituted alkyl group having 1 to 8 carbon atoms, and an unsubstituted aryl group having 6 to 15 carbon atoms.

In general formula (iii) or (iv), R ³ , R ⁴ and R ⁵ may be the same or different and each represents a single bond or a divalent linking group. Examples of such a divalent linking group include aliphatic hydrocarbons and aromatic hydrocarbons. Here, R ³ , R ⁴ and R ⁵ may have a substituent, and examples of the substituent that can be introduced include an alkyl group, an aralkyl group, an aryl group, an alkoxy group, and a halogen atom (—F, —Cl , -Br, -I) and the like.

Preferred examples of R ³ , R ⁴ , and R ⁵ include an unsubstituted alkylene group having 1 to 20 carbon atoms and an unsubstituted arylene group having 6 to 15 carbon atoms. Eight unsubstituted alkylene groups can be mentioned. If necessary, R ³ , R ⁴ and R ⁵ are other functional groups that do not react with the isocyanate group in the general formula (ii) (for example, ester group, urethane group, amide group, ureido group, ether group). You may have.

R ² , R ³ , R ⁴ and R ⁵ may be bonded to each other to form a ring structure.

  In general formula (iv), Ar represents the trivalent aromatic hydrocarbon which may have a substituent, Preferably it shows a C6-C15 aromatic group.

  Specific examples of the diisocyanate compound represented by the general formula (ii) include those shown below, but the present invention is not limited thereto.

  2,4-tolylene diisocyanate, dimer of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylylene diisocyanate, metaxylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5 -Aromatic diisocyanate compounds such as naphthylene diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate; aliphatic diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer acid diisocyanate; Isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) diisocyanate, 1,3- (i Cyanate methyl) alicyclic diisocyanate compounds such as such as cyclohexane; 1,3-butylene glycol 1 mol of a diisocyanate compound which is a reaction product of such a diol and a diisocyanate, an adduct of tolylene diisocyanate 2 mol, and the like.

  Among these, those having an aromatic ring such as 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, and tolylene diisocyanate are preferable from the viewpoint of scratch resistance.

  Specific examples of the diol compound having a carboxyl group represented by the general formula (iii) or (iv) include those shown below, but the present invention is not limited thereto.

  3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxyethyl) propionic acid, 2,2-bis (3-hydroxypropylpropionic acid, 2,2-bis (Hydroxymethyl) acetic acid, bis- (4-hydroxyphenyl) acetic acid, 4,4-bis- (4-hydroxyphenyl) pentanoic acid, tartaric acid and the like.

  Among these, 2,2-bis (hydroxymethyl) propionic acid and 2,2-bis (hydroxyethyl) propionic acid are preferable from the viewpoint of reactivity with isocyanate.

  The polyurethane resin was formed by using two or more diisocyanate compounds represented by the general formula (ii) and two or more diol compounds having a carboxyl group represented by the general formula (iii) or (iv). It may be a thing.

  In addition to the diol compound having a carboxyl group represented by the general formula (iii) or (iv), the diol compound does not have a carboxyl group and has a substituent that does not react with the isocyanate group in the formula (ii). The diol compound that may be used may be used in combination so as not to lower the alkali developability.

  The polyurethane resin can be synthesized by adding the above-mentioned diisocyanate compound and diol compound in an aprotic solvent to a known catalyst having an activity corresponding to the reactivity and heating.

  The molar ratio of the diisocyanate and the diol compound to be used is preferably 0.8: 1 to 1.2: 1. When an isocyanate group remains at the polymer terminal, the final treatment is performed with an alcohol or an amine. Thus, it is synthesized in a form in which no isocyanate group remains.

  The molecular weight of the polyurethane resin is preferably 1,000 or more in terms of weight average molecular weight, and more preferably in the range of 5,000 to 100,000. These polyurethane resins may be used alone or in combination of two or more.

  Next, a water-insoluble and alkali-soluble polyvinyl acetal resin will be described. The polyvinyl acetal resin used here is not particularly limited as long as it is insoluble in water and soluble in an alkaline aqueous solution, but among them, the polyvinyl acetal resin represented by the following general formula (v) is preferable.

  Among the structural units, the polyvinyl acetal resin represented by the general formula (v) is essentially composed of the structural unit (i) that is a vinyl acetal component and the structural unit (iv) that is an ester component containing a carboxyl group. The structural unit (ii) that is an alcohol component and the structural unit (iii) that is an unsubstituted ester component are used as optional components, and the structural unit is formed from structural units (i) to (iv). Can have. In addition, n1-n4 shows the structural ratio (mol%) of each structural unit.

In the structural unit (i), R ¹ represents an alkyl group which may have a substituent, a hydrogen atom, a carboxyl group, or a dimethylamino group. Examples of the substituent include a carboxyl group, a hydroxyl group, a chloro group, a bromo group, a urethane group, a ureido group, a tertiary amino group, an alkoxy group, a cyano group, a nitro group, an amide group, and an ester group.

Specific examples of R ¹ in the structural unit (i) include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a carboxy group, a halogen atom (—Br, —Cl, etc.) or a cyano group. Methyl group, 3-hydroxybutyl group, 3-methoxybutyl group, phenyl group and the like, among which hydrogen atom, propyl group, and phenyl group are particularly preferable.

  n1 is preferably in the range of 5 to 85 mol%, and more preferably in the range of 25 to 70 mol%.

  n2 is preferably in the range of 0 to 60 mol%, more preferably in the range of 10 to 45 mol%.

In the structural unit (iii), R ² represents an alkyl group having no substituent. Among these, an alkyl group having 1 to 10 carbon atoms is preferable, and a methyl group and an ethyl group are particularly preferable from the viewpoint of developability.

  n3 is preferably in the range of 0 to 20 mol%, more preferably in the range of 1 to 10 mol%.

In the structural unit (iv), R ³ represents an aliphatic hydrocarbon group having a carboxyl group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, and these hydrocarbon groups have 1 to 20 carbon atoms. Preferably there is. In addition, these hydrocarbon groups in the structural unit (iv) mainly include succinic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, and the like. It is preferable that it is a hydrocarbon group obtained by reacting the acid anhydride of the above and the residual -OH of polyvinyl acetal, and among them, those obtained by reacting phthalic anhydride and succinic anhydride are more preferred. Moreover, what was obtained using another cyclic acid anhydride may be used.

R ³ in the structural unit (iv) may have a substituent other than a carboxyl group. Examples of such a substituent include those represented by the following structures.

In the above formula, as R ⁴ , an optionally substituted alkyl group having 1 to 20 carbon atoms, an aralkyl group, or an aryl group is raised, and the substituents that can be introduced here are —OH, —C ≡N, —CL, —Br, —NO ₂ .

Specific examples of R ³ in the structural unit (iv) include the following, but the present invention is not limited thereto.

  n4 is preferably in the range of 3 to 60 mol%, and more preferably in the range of 10 to 55 mol% from the viewpoint of developability.

  The polyvinyl acetal resin represented by the general formula (v) can be synthesized by a method in which polyvinyl alcohol is acetalized with an aldehyde and the remaining hydroxy group is reacted with an acid anhydride.

  Examples of the aldehyde used herein include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, pentylaldehyde, hexylaldehyde, glyoxylic acid, N, N-dimethylformamide di-n-butyl acetal, bromoacetaldehyde, chloroacetaldehyde, 3-hydroxy- Examples include, but are not limited to, n-butyraldehyde, 3-methoxy-n-butyraldehyde, 3- (dimethylamino) -2,2-dimethylpropionaldehyde, cyanoacetaldehyde, and the like.

  The acid content of the polyvinyl acetal resin is preferably in the range of 0.5 to 5.0 meq / g (that is, 84 to 280 in terms of mg of KOH), and is 1.0 to 3.0 meq / g. Is more preferable.

  The molecular weight of the polyvinyl acetal resin is preferably about 5,000 to 400,000, more preferably about 20,000 to 300,000, as a weight average molecular weight measured by gel permeation chromatography. In addition, these polyvinyl acetal resins may be used independently or may be used in mixture of 2 or more types.

  The alkali-soluble resin used for the lower layer can be used alone or in combination of two or more.

  In the case of a single-layer recording layer, the content of the alkali-soluble resin relative to the total solid content of the recording layer is preferably 30 to 99% by mass, more preferably 40%, from the viewpoint of the sensitivity and durability of the recording layer. It is -95 mass%.

In the case of a multilayer type recording layer, the content of the alkali-soluble resin relative to the total solid content of the uppermost layer is preferably 40 to 98% by mass, more preferably 60%, from the viewpoint of the sensitivity and durability of the recording layer. It is -97 mass%.
The content of the alkali-soluble resin in the lower layer component is preferably 40 to 95 mass%, more preferably 50 to 90 mass%, in the total solid content of the lower layer.

(Development inhibitor)
The recording layer can contain a development inhibitor for the purpose of enhancing its inhibition (dissolution inhibiting ability). In the case where the recording layer has a multilayer structure, it is particularly preferable to include a development inhibitor in the uppermost layer.

  As a development inhibitor, it forms an interaction with the alkali-soluble resin, substantially reduces the solubility of the alkali-soluble resin in the developer in the unexposed area, and weakens the interaction in the exposed area. Any quaternary ammonium salt or polyethylene glycol compound is preferably used as long as it can be soluble in the developer. Among the photothermal conversion agents and image colorants described below, there are compounds that function as development inhibitors, and these are also preferred.

  The quaternary ammonium salt is not particularly limited, and examples thereof include tetraalkylammonium salt, trialkylarylammonium salt, dialkyldiarylammonium salt, alkyltriarylammonium salt, tetraarylammonium salt, cyclic ammonium salt, and bicyclic ammonium salt. It is done.

  Specifically, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, tetraoctylammonium bromide, tetralaurylammonium bromide, tetraphenylammonium bromide, tetranaphthylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide , Tetrastearyl ammonium bromide, lauryl trimethyl ammonium bromide, stearyl trimethyl ammonium bromide, behenyl trimethyl ammonium bromide, lauryl triethyl ammonium bromide, phenyl trimethyl ammonium bromide, 3-trifluoromethylphenyl trimethyl ammonium bromide, benzyl trimethyl ammonium bromide De, dibenzyl dimethyl ammonium bromide, distearyl dimethyl ammonium bromide, tristearyl methyl ammonium bromide, benzyl triethyl ammonium bromide, hydroxyphenyl trimethyl ammonium bromide, N- methyl pyridinium bromide, and the like. In particular, quaternary ammonium salts described in Japanese Patent Application Nos. 2001-226297, 2001-370059, and 2001-398047 are preferable.

  From the viewpoint of the development inhibiting effect and the film-forming property of the alkali-soluble resin, the addition amount of the quaternary ammonium salt is 0.1 to 50 mass with respect to the total solid content of the recording layer when the recording layer is a single layer type. %, Preferably 1 to 30% by mass. In the case of a multi-layer type recording layer, it is preferably 0.1 to 50% by mass, more preferably 1 to 30% by mass with respect to the total solid content of the uppermost layer.

  Moreover, it does not specifically limit as a polyethyleneglycol compound, However, The thing of the structure represented by the following general formula (vi) is mentioned.

^{R 61 - {- O- (R} 63 -O-) m -R 62} n ··· formula (vi)
In the general formula (vi), R ⁶¹ represents a polyhydric alcohol residue or a polyhydric phenol residue, R ⁶² represents a hydrogen atom, an alkyl group having 1 to 25 carbon atoms which may have a substituent, An alkenyl group, an alkynyl group, an alkylyl group, an aryl group or an aryloyl group is represented. R ⁶³ represents an alkylene residue which may have a substituent, m represents an integer of 10 or more on average, and n represents an integer of 1 to 4.

  Examples of the polyethylene glycol compound represented by the general formula (vi) include polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, polyethylene Glycol alkyl aryl ethers, polypropylene glycol alkyl aryl ethers, polyethylene glycol glycerin esters, polypropylene glycol glycerin esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyethylene glycol Ethylenediamines, polypropylene glycolated ethylenediamines, polyethylene glycolated diethylenetriamine, and polypropylene glycol diethylenetriamines.

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

  From the viewpoint of the development inhibiting effect and image formability, the addition amount of the polyethylene glycol compound is preferably 0.1 to 50% by mass with respect to the total solid content of the recording layer when the recording layer is a single layer type. 1 to 30% by mass is more preferable. In the case of a multilayer recording layer, the content is preferably 0.1 to 50% by mass, more preferably 1 to 30% by mass, based on the total solid content of the uppermost layer.

  In addition, when such a measure for increasing the inhibition (dissolution suppression ability) is performed, the sensitivity is lowered. As a countermeasure, the lactone compound described in JP-A-2002-361666 is used in the uppermost layer. It is effective to add to to suppress the decrease in sensitivity.

  In addition to the above, as a dissolution inhibitor, an onium salt, an o-quinonediazide compound, an aromatic sulfone compound, an aromatic sulfonic acid ester compound, etc. are dissolved in an alkali-soluble resin in a thermally decomposable and non-decomposable state. It is preferable to use a substance that substantially reduces the property in view of improving the inhibition of the image portion in the developer.

  Examples of the onium salt used in the present invention include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, arsonium salts, and the like. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Balet al, Polymer, 21, 423 (1980), diazonium salts described in JP-A-5-158230, U.S. Pat. Nos. 4,069,055 and 4,069,056, JP-A-3- An ammonium salt described in Japanese Patent No. 140140; C. Necker et al, Macromolecules, 17, 2468 (1984), C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, U.S. Pat. Nos. 5,041,358 and 4,491,628, JP-A-2-150848, JP-A-2-296514. Iodonium salts described in each publication; V. Crivello et al, Polymer J. et al. 17, 73 (1985), J. Am. V. Crivello et al. J. et al. Org. Chem. 43, 3055 (1978); R. Watt et al, J.A. PolymerSci. , Polymer Chem. Ed. , 22, 1789 (1984), J. Am. V. Crivello et al, Polymer Bull. 14, 279 (1985), J. Am. V. Crivello et al, Macromolecules, 14 (5), 1141 (1981), J. MoI. V. Crivello et al, J. MoI. PolymerSci. , Polymer Chem. Ed. 17, 2877 (1979), European Patents 370,693, 233,567, 297,443, 297,442, U.S. Pat. Nos. 4,933,377, 3,902,114 No. 4,491,628, No. 4,760,013, No. 4,734,444, No. 2,833,827, German Patent No. 2,904,626, No. 3,604 The sulfonium salts described in each specification of Nos. 580 and 3,604,581; V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J. MoI. PolymerSci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988).

  Of these onium salts, a diazonium salt is particularly preferable. Particularly suitable diazonium salts include those described in JP-A-5-158230.

  The counter ion of the onium salt includes tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfone Mention may be made of anions from acids, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, paratoluenesulfonic acid and the like. Among these, anions from alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid are particularly preferable.

  Suitable quinonediazides include o-quinonediazide compounds. The o-quinonediazide compound used in the present invention is a compound having at least one o-quinonediazide group, which increases alkali solubility by thermal decomposition, and compounds having various structures can be used. That is, o-quinonediazide assists the solubility of the uppermost layer by both the effects of losing the inhibition as a development inhibitor due to thermal decomposition and the change of o-quinonediazide itself into an alkali-soluble substance.

  Examples of such o-quinonediazide compounds include J. Org. The compounds described in pages 339 to 352 of “Light-sensitive systems” by John Coley (John Wiley & Sons. Inc.) can be used, and in particular, o-quinonediazide reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. The sulfonic acid esters or sulfonic acid amides are preferred. Further, benzoquinone (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2-diazide sulfonic acid chloride or naphthoquinone- (1,2)-described in U.S. Pat. Nos. 3,046,120 and 3,188,210. Esters of diazide-5 sulfonic acid chloride and phenol-formaldehyde resins are also preferably used.

  Further, esters of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride with phenol formaldehyde resin or cresol-formaldehyde resin, naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and pyrogallol-acetone resin Similarly, the esters are also preferably used. Other useful o-quinonediazide compounds are reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802, JP-A-48-63803, JP-A-48-96575, JP-A-49-38701, JP-A-48-13354, Japanese Patent Publication Nos. 41-11222, 45-9610, 49-17478, and U.S. Pat. Nos. 2,797,213, 3,454,400, and 3,544 No. 323, No. 3,573,917, No. 3,674,495, No. 3,785,825, British Patent No. 1,227,602, No. 1,251,345, No. Nos. 1,267,005, 1,329,888, 1,330,932, and German Patent No. 854,890 can be cited. .

  In the case of a single-layer recording layer, the addition amount of the o-quinonediazide compound is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, based on the total solid content of the recording layer. In the case of a multi-layer type recording layer, the content is in the range of 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass with respect to the total solid content of the uppermost layer. These compounds can be used alone, but may be used as a mixture of several kinds.

Further, for the purpose of enhancing the inhibition of the surface of the recording layer and the scratch resistance of the surface, the perfluoro having 3 to 20 carbon atoms in the molecule as described in JP-A-2000-187318 is also disclosed. It is preferable to use a polymer having a polymerization component of a (meth) acrylate monomer having 2 or 3 alkyl groups.
The addition amount is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass with respect to the total solid content of the recording layer in the case of a single-layer type recording layer. In the case of a multilayer type recording layer, the content is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the uppermost layer.

(Infrared absorber)
The infrared absorber in this invention is demonstrated.
The lithographic printing plate precursor according to the invention can be recorded by an infrared laser by containing an infrared absorber having a maximum absorption in the infrared region and having a photothermal conversion ability.
The infrared absorbent used in the present invention is not particularly limited as long as it is a dye that absorbs infrared light or near infrared light and generates heat, and various dyes known as infrared absorbents can be used.

  When the recording layer in the present invention is a single-layer type recording layer, the recording layer needs to contain an infrared absorber. When the recording layer in the present invention has a multilayer structure, at least one of the lower layer and the uppermost layer is a layer containing an infrared absorber, and is preferably added to both the lower layer and the uppermost layer.

  As the infrared absorber, commercially available dyes and known ones described in literature (for example, “Dye Handbook” edited by the Society of Synthetic Organic Chemistry, published in 1970) can be used. Specific examples include azo dyes, metal complex azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, and cyanine dyes. In the present invention, among these dyes, those that absorb infrared light or near-infrared light are particularly preferred because they are suitable for use in lasers that emit infrared light or near-infrared light.

  Preferred dyes are described in, for example, JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, US Pat. No. 4,973,572, and the like. Cyanine dyes, methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc., JP-A-58-112793, JP-A-58- Naphthoquinone dyes described in JP-A Nos. 224793, 59-48187, 59-73996, 60-52940, 60-63744, etc. Examples include squarylium dyes described in Japanese Patent No. 112792, and cyanine dyes described in British Patent 434,875.

  As the dye, a near-infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and substituted dyes described in US Pat. No. 3,881,924 are also used. Arylbenzo (thio) pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, and 58-220143 No. 59-41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, and JP-A 59-216146. Cyanine dyes, pentamethine thiopyrylium salts described in U.S. Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds disclosed in JP-is, as commercially available products, Eporin Co. Epolight III-178, Epolight III-130, Epolight III-125 and the like are particularly preferably used.

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

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferable, and one particularly preferable example is a cyanine dye represented by the following general formula (a).

In formula (a), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. W ¹⁻ is defined in the same manner as Xa ⁻ described later, and R ^a represents a substituent selected from a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom.

In general formula (a), R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring or It is particularly preferable that a 6-membered ring is formed.
Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Xa ⁻ represents a counter anion. However, when the cyanine dye represented by the general formula (a) has an anionic substituent in the structure and charge neutralization is not necessary, W ¹⁻ is not necessary. Preferred Xa ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, and particularly preferably a perchlorate ion, a hexagonal salt, in view of the storage stability of the recording layer coating solution. Fluorophosphate ions and aryl sulfonate ions.

In the case of a multilayer recording layer, the infrared absorber is preferably added to the uppermost layer of the recording layer or in the vicinity thereof from the viewpoint of sensitivity. In particular, when a substance having a dissolution inhibiting ability such as a cyanine dye is added together with an alkali-soluble resin having a phenol group, the unexposed area can be made resistant to alkali at the same time as the sensitivity is increased. These infrared absorbers may be added to the lower layer or both the uppermost layer and the lower layer. By adding to the lower layer, it is possible to further increase the sensitivity. When an infrared absorber is added to both the uppermost layer and the lower layer, the same compound may be used, or different compounds may be used.
Further, the infrared absorber may be added to a layer different from the recording layer. In the case of a separate layer, it is desirable to add to a layer adjacent to the recording layer.

  As the addition amount of the infrared absorber, in the case of a single-layer type recording layer, it is preferably added in an amount of 3 to 50% by mass, more preferably 5 to 40% by mass, based on the total solid content of the recording layer. In the case of a multi-layer type recording layer, when added to the uppermost recording layer, 0.01 to 50% by mass, preferably 0.1 to 30% by mass, particularly preferably 1. It is 0-30 mass%. By setting the addition amount in the above range, the sensitivity and durability of the recording layer are improved. Moreover, when adding to a lower layer, it is 0-20 mass% with respect to a lower layer total solid, Preferably it is 0-10 mass%, Most preferably, it can add in the ratio of 0-5 mass%.

  When an infrared absorber is added to the lower layer, the solubility of the lower layer decreases if an infrared absorber having dissolution inhibiting ability is used. On the other hand, the infrared absorber generates heat during infrared laser exposure, and the solubility of the lower layer is improved by heat. Therefore, the compound to be added and the addition amount should be selected in consideration of these balances. In the region of 0.2 to 0.3 μm in the vicinity of the support, it is difficult to obtain the effect of improving the solubility due to heat, for example, the heat generated during exposure diffuses to the support. In some cases, the decrease in sensitivity may cause a decrease in sensitivity. Therefore, even within the range of the addition amount shown above, such an addition amount that the dissolution rate in the lower layer developer (25 to 30 ° C.) is lower than 30 nm / sec is not preferable.

(Other additives)
In forming the recording layer, in addition to the above components, various additives can be further added as necessary as long as the effects of the present invention are not impaired.
In the case of a multilayer recording layer, the additives listed below may be added only to the lower layer of the recording layer, may be added only to the uppermost layer, or may be added to both layers. Good.

<Development accelerator>
For the purpose of improving sensitivity, acid anhydrides, phenols, and organic acids may be added to the recording layer.

  As the acid anhydrides, cyclic acid anhydrides are preferable. Specific examples of the cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride described in US Pat. No. 4,115,128. Acid, 3,6-endooxy-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Examples of the acyclic acid anhydride include acetic anhydride.

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

  Examples of organic acids include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid , P-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like.

In the case of a single layer type recording layer, the proportion of acid anhydrides, phenols and organic acids in the total solid content of the recording layer is preferably 0.05 to 20%, more preferably 0.1 to 15% by mass, Especially preferably, it is 0.1-10 mass%. In the case of a multi-layer type recording layer, the ratio of acid anhydrides, phenols and organic acids to the total solid content of the lower layer or the uppermost layer of the recording layer is preferably 0.05 to 20% by mass, more preferably 0.8%. 1 to 15% by mass, particularly preferably 0.1 to 10% by mass.

<Surfactant>
In order to improve the coatability of the recording layer and to expand the stability of the processing with respect to the development conditions, non-printing methods such as those described in Japanese Patent Application Laid-Open Nos. 62-251740 and 3-208514 are proposed. Ionic surfactants, amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, and siloxane compounds as described in European Patent No. 950517 Copolymers of fluorine-containing monomers as described in JP-A-62-170950, JP-A-11-288093, and JP-A-2003-057820 can be added.

In the case of a single-layer type recording layer, the ratio of the surfactant to the total solid content of the recording layer is preferably 0.01 to 15% by mass, more preferably 0.1 to 5% by mass, and particularly preferably 0.8. It is 05-0.5 mass%.
In the case of a multilayer type recording layer, the ratio of the surfactant recording layer lower layer or uppermost layer to the total solid content is preferably 0.01 to 15% by mass, more preferably 0.1 to 5.0% by mass. %, More preferably 0.05 to 2.0% by mass.

<Bake-out agent / colorant>
A print-out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant can be added to the recording layer.

  A representative example of the printing-out agent is a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt. Specifically, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A-50-36209 and JP-A-53-8128, 36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440, and trihalomethyl compounds and salt-forming organic dyes Can be mentioned. Such trihalomethyl compounds include oxazole-based compounds and triazine-based compounds, both of which have excellent temporal stability and give clear printout images.

  As the image colorant, other dyes can be used in addition to the aforementioned salt-forming organic dyes. Examples of suitable dyes including salt-forming organic dyes include oil-soluble dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (oriental chemical industry) Co., Ltd.), Victoria Pure Blue, Crystal Violet Lactone, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI52015), etc. it can. The dyes described in JP-A-62-293247 are particularly preferred.

In the case of a single layer type recording layer, these dyes can be added in a proportion of 0.01 to 10% by mass, preferably 0.1 to 3% by mass, based on the total solid content of the recording layer.
In the case of a multi-layer type recording layer, it can be added at a ratio of 0.01 to 10% by mass, preferably 0.1 to 3% by mass, based on the total solid content of the lower layer or the uppermost layer of the recording layer.

<Plasticizer>
A plasticizer may be added to the recording layer in order to impart flexibility of the coating film.
For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid These oligomers and polymers are used.

When these plasticizers are single layer type recording layers, they should be added in a proportion of 0.5 to 10% by mass, preferably 1.0 to 5.0% by mass, based on the total solid content of the recording layer. Can do.
In the case of a recording layer having a multilayer structure, it may be added in a proportion of 0.5 to 10% by mass, preferably 1.0 to 5.0% by mass, based on the total solid content of the lower layer or the uppermost layer of the recording layer. it can.

<WAX agent>
A compound that lowers the coefficient of static friction of the surface can be added to the uppermost layer of the single-layer type recording layer or the multi-layer type recording layer according to the present invention for the purpose of imparting resistance to scratches. Specifically, it is described in US Pat. No. 6,117,913, or Japanese Patent Application Nos. 2001-261627, 2002-032904, and 2002-165854 previously proposed by the applicant of the present application. And compounds having long-chain alkyl carboxylic acid esters.
As for the addition amount, in the case of a single layer type recording layer, it is added in a proportion of 0.1 to 10% by mass, preferably 0.5 to 5.0% by mass, based on the total solid content of the recording layer. it can.
In the case of a recording layer having a multilayer structure, the proportion of the recording layer in the uppermost layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass.

(Formation of recording layer)
The recording layer in the lithographic printing plate precursor according to the invention can be formed by dissolving each component constituting the recording layer in a solvent and applying it.

  Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and toluene. It is not limited. These solvents are used alone or in combination.

  In the case of a multi-layer type recording layer, the lower layer and the uppermost layer of the recording layer are preferably formed by separating the two layers in principle.

As a method of forming the two layers separately, for example, a method using the difference in solvent solubility between the component contained in the lower layer and the component contained in the uppermost layer, or after applying the uppermost layer, Examples include a method of drying and removing the solvent.
Details of these methods are described in JP-A No. 2002-251003.

  In addition, in order to provide a new function, the uppermost layer and the lower layer may be partly compatible in a range where the effects of the present invention are sufficiently exhibited. In this case, partial compatibility can be achieved by controlling the difference in solvent solubility, the drying rate of the solvent after the uppermost layer is applied, and the like.

  The concentration of the above components excluding the solvent (total solid content including additives) in the recording layer coating solution to be coated on the support is preferably 1 to 50% by mass.

Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

  In particular, in the multi-layer type recording layer, it is desirable that the top layer coating method is a non-contact type in order to prevent damage to the lower layer when the top layer is applied. Further, although it is a contact type, it is possible to use bar coater coating as a method generally used for solvent-based coating, but it is desirable to perform coating by forward rotation in order to prevent damage to the lower layer.

In the case of a single layer type recording layer, the coating amount after drying of the recording layer is preferably in the range of 0.3 to 3.0 g / m ² , more preferably 0.5 to 2.5 g / m ^2. The range is m ² .

For the multilayer type recording layer, the coating amount after drying of a lower layer component is preferably in the range of 0.5 to 4.0 g / m ^2, more preferably 0.6 to 2.5 g / m ² Range. When it is 0.5 g / m ² or more, printing durability is excellent, and when it is 4.0 g / m ² or less, good image reproducibility and sensitivity are obtained.
The coating amount after drying of the top layer components is preferably in the range of 0.05 to 1.0 g / m ^2, more preferably in the range of 0.08 to 0.7 g / m ^2. With 0.05 g / m ² or more, good developing latitude, scratch resistance can be obtained, good sensitivity can be obtained by a 1.0 g / m ² or less.

The lower layer and the coating amount after drying of the combined top layer, preferably in the range of 0.6~4.0g / m ^2, more preferably in the range of 0.7 to 2.5 g / m ² . When the amount is 0.6 g / m ² or more, good printing durability is obtained, and when the amount is 4.0 g / m ² or less, good image reproducibility and sensitivity are obtained.

[Back coat layer]
The lithographic printing plate precursor according to the invention has a backcoat layer (hereinafter simply referred to as “back coating layer”) having a thickness of 0.3 μm or more containing an organic polymer on the surface opposite to the surface having the recording layer of the support (back surface of the support). It may be referred to as a “backcoat layer”).
The thickness of the back coat layer in the present invention is required to be 0.3 μm or more, and is preferably from 0.3 μm to 50 μm from the viewpoint of improving printing durability and stability of printing dimensions. More preferably, it is 0.5 μm to 25 μm, and particularly preferably 1.0 μm to 20 μm.
Hereinafter, the back coat layer will be described in detail.

(Organic polymer)
The back coat layer contains an organic polymer. As the organic polymer, a back coat layer can be formed and can be selected without particular limitation as long as the effects of the present invention are not impaired. Hereinafter, although the organic polymer used suitably for a backcoat layer is mentioned, it is not limited to this.

  Phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (any of m-, p-, or m- / p-mixed) mixed formaldehyde Examples thereof include novolak resins such as resins and pyrogallol acetone resins.

Examples thereof include at least one resin selected from the group consisting of a saturated copolymerized polyester resin, a phenoxy resin, a polyvinyl acetal resin, and a vinylidene chloride copolymer resin.
The saturated copolyester resin is composed of a dicarboxylic acid unit and a diol unit. The dicarboxylic acid unit of the polyester used in the present invention includes aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid; adipic acid, azelaic acid, succinic acid, succinic acid, and suberic acid , Saturated aliphatic dicarboxylic acids such as sebacic acid, malonic acid, and 1,4-cyclohexanedicarboxylic acid.

Examples of the diol unit include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, neo Aliphatic chain diols such as pentyl glycol, hexanediol, 2,2,4-trimethyl-1,3-pentanediol; 1,4-bis-β-hydroxyethoxycyclohexane, cyclohexanedimethanol, tricyclodecane dimethanol, And cyclic diols such as bisphenol dioxyethyl ether and bisphenol dioxypropyl ether.
These dicarboxylic acid and diol units are each at least one or more, and either one is used as two or more copolymer units, and the properties of the copolymer are determined by the copolymer composition and molecular weight.

  The back coat layer in the present invention can be provided by thermocompression bonding of a film or a melt lamination method, but application from a solution is more preferable for efficiently providing a thin layer. Therefore, when a copolyester resin is used as the organic polymer, it is preferably non-crystalline and easily soluble in various industrial organic solvents.

  When a copolyester resin is used as the organic polymer, the molecular weight is preferably 10,000 or more from the viewpoint of the film strength of the backcoat layer.

  Phenoxy resin, like epoxy resin, is manufactured from bisphenol A and epichlorohydrin, but has superior chemical resistance and adhesiveness without the aid of curing agents and catalysts compared to epoxy resin, and is the main component of backcoat. It is suitable as.

  The polyvinyl acetal resin is a resin obtained by acetalizing polyvinyl alcohol with an aldehyde such as butyraldehyde or formaldehyde, and a polyvinyl butyral resin or a polyvinyl formal resin is preferably used. These polyvinyl acetal resins differ in physical properties and chemical properties depending on the degree of acetalization, the composition ratio of hydroxyl groups and acetyl groups, and the degree of polymerization. However, in the backcoat layer of the present invention, the glass transition temperature is 60 ° C. or higher. Is preferred.

  Examples of vinylidene chloride copolymer resins include copolymer resins of vinylidene chloride monomers and vinyl monomers such as vinyl chloride, vinyl acetate, ethylene, and vinyl methyl ether, and acrylic monomers such as (meth) acrylic acid esters and (meth) acrylonitrile. Used. Among these, a vinylidene chloride copolymer containing acrylonitrile in a range of 20 mol% or less is preferable because of its high solubility in general-purpose organic solvents.

  As the organic polymer contained in the backcoat layer, other hydrophobic polymer compounds shown below can also be applied. Examples of such hydrophobic polymer compounds include polybutene, polybutadiene, polyamide, unsaturated copolymerized polyester resin, polyurethane, polyurea, polyimide, polysiloxane, polycarbonate, epoxy resin, chlorinated polyethylene, alkylphenol aldehyde condensation resin, polychlorinated resin. Vinyl, polyvinylidene chloride, polystyrene, acrylic resins and copolymer resins thereof, hydroxycellulose, polyvinyl alcohol, cellulose acetate, carboxymethylcellulose, and the like are suitable.

  As other suitable hydrophobic polymer compounds, there can be mentioned copolymers having a molecular weight of usually 10,000 to 200,000 having the monomers shown in the following (1m) to (12m) as structural units.

(1m) Acrylamides, methacrylamides, acrylic esters, methacrylic esters and hydroxystyrenes having an aromatic hydroxyl group, such as N- (4-hydroxyphenyl) acrylamide or N- (4-hydroxyphenyl) methacrylamide O, m- and p-hydroxystyrene, o-, m- and p-hydroxyphenyl acrylate or methacrylate.
(2m) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.

(3m) methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, phenyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, (Substituted) acrylic acid esters such as 4-hydroxybutyl acrylate, glycidyl acrylate, and N-dimethylaminoethyl acrylate.
(4m) methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, (Substituted) methacrylate esters such as 4-hydroxybutyl methacrylate, glycidyl methacrylate, and N-dimethylaminoethyl methacrylate.

  (5m) Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-ethyl methacrylamide, N-hexyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-cyclohexyl methacryl Amide, N-hydroxyethylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-phenylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N-nitrophenylacrylamide, N-nitrophenylmethacrylamide, N Acrylamide or methacrylic acid such as ethyl-N-phenylacrylamide and N-ethyl-N-phenylmethacrylamide De.

(6m) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(7m) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(8m) Styrenes such as styrene, methylstyrene, and chloromethylstyrene.
(9m) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(10m) Olefin such as ethylene, propylene, isobutylene, butadiene, isoprene.
(11m) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.

  (12m) N- (o-aminosulfonylphenyl) acrylamide, N- (m-aminosulfonylphenyl) acrylamide, N- (p-aminosulfonylphenyl) acrylamide, N- [1- (3-aminosulfonyl) naphthyl] acrylamide Acrylamides such as N- (2-aminosulfonylethyl) acrylamide, N- (o-aminosulfonylphenyl) methacrylamide, N- (m-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) methacryl Methacrylamides such as amide, N- [1- (3-aminosulfonyl) naphthyl] methacrylamide, N- (2-aminosulfonylethyl) methacrylamide, o-aminosulfonylphenyl acrylate, m-aminosulfonate Unsaturated sulfonamides such as acrylic acid esters such as phenyl acrylate, p-aminosulfonylphenyl acrylate, 1- (3-aminosulfonylphenylnaphthyl) acrylate, o-aminosulfonylphenyl methacrylate, m-aminosulfonylphenyl methacrylate, p- Unsaturated sulfonamides such as methacrylic acid esters such as aminosulfonylphenyl methacrylate and 1- (3-aminosulfonylphenylnaphthyl) methacrylate.

  Furthermore, a monomer that can be copolymerized with the monomer may be copolymerized. Moreover, what modified the copolymer obtained by copolymerization of the said monomer with glycidyl acrylate, glycidyl methacrylate, etc. is contained, for example, It is not restricted to these.

  These other hydrophobic polymer compounds may be used alone or in combination of two or more. Further, when used in combination with a saturated copolymerized polyester resin, a phenoxy resin, a polyvinyl acetal resin, and / or a vinylidene chloride copolymer resin, it can be added in a range of 50% by mass or less based on the total solid content of the backcoat layer. However, in order to make use of the properties of these resins, the content is preferably 30% by mass or less.

  The content of the organic polymer contained in the total solid content of the back coat layer is preferably 99.99 to 70% by mass, more preferably 99.9 to 80% by mass, and 99.5 to 90% by mass. It is particularly preferred.

(Other ingredients)
In the back coat layer, for the purpose of imparting flexibility, adjusting the slipperiness and improving the coating surface state, a plasticizer, a surfactant, and other additives are necessary as long as the effects of the present invention are not impaired. Can be added.

  Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate, and the like. Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate, phosphate esters such as tricresyl phosphate, triphenyl phosphate , Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl seba Over DOO, dioctyl azelate, aliphatic, such as dibutyl maleate dibasic acid esters, polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, and butyl laurate is effective.

  Although the addition amount of a plasticizer changes with kinds of organic polymer used for a backcoat layer, it is preferable to add in the range from which a glass transition temperature does not become 60 degrees C or less.

  Examples of the surfactant include anionic, cationic, nonionic and amphoteric surfactants. Specific examples include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters , Pentaerythritol fatty acid partial esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters , Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamine , N, N-bis-2-hydroxyalkylamines, nonionic surfactants such as polyoxyethylene alkylamine, triethanolamine fatty acid ester, trialkylamine oxide, fatty acid salts, abietic acid salts, hydroxyalkanesulfone Acid salts, alkane sulfonates, dialkyl sulfosuccinate esters, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates,

  Polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef oil, sulfate esters of fatty acid alkyl esters, alkyl Sulfuric acid ester salts, polyoxyethylene alkyl ether sulfuric acid ester salts, fatty acid monoglyceride sulfuric acid ester salts, polyoxyethylene alkylphenyl ether sulfuric acid ester salts, polyoxyethylene styryl phenyl ether sulfuric acid ester salts, alkyl phosphoric acid ester salts, polyoxyethylene alkyl ether Phosphoric acid ester salts, polyoxyethylene alkylphenyl ether phosphoric acid ester salts, partially saponified products of styrene / maleic anhydride copolymer, olefin / Anionic surfactants such as partially saponified products of water maleic acid copolymer, naphthalene sulfonate formalin condensates, cations such as alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, polyethylene polyamine derivatives Amphoteric surfactants such as ionic surfactants, carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, imidazolines, and the like. Among the surfactants listed above, those having polyoxyethylene can be read as polyoxyalkylenes such as polyoxymethylene, polyoxypropylene and polyoxybutylene, and these surfactants are also included.

  A more preferred surfactant is a fluorosurfactant containing a perfluoroalkyl group in the molecule. Examples of fluorosurfactants include perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, anionic types such as perfluoroalkyl phosphates, amphoteric types such as perfluoroalkyl betaines, and perfluoroalkyltrimethylammonium salts. Cationic and perfluoroalkylamine oxides, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl group and hydrophilic group-containing oligomers, perfluoroalkyl group and lipophilic group-containing oligomers, perfluoroalkyl groups, hydrophilic groups and parent Nonionic types such as oil-based group-containing oligomers, perfluoroalkyl groups, and lipophilic group-containing urethanes may be mentioned.

  Surfactant can be used individually or in combination of 2 or more types, Preferably it is 0.001-10 mass% in a backcoat layer, More preferably, it can add in 0.01-5 mass%.

  The back coat layer further includes a dye for coloring, a silane coupling agent for improving adhesion to the aluminum support, a diazo resin composed of a diazonium salt, an organic phosphonic acid, an organic phosphoric acid, and a cationic polymer. Can be appropriately added wax, higher fatty acids, higher fatty acid amides, silicone compounds composed of dimethylsiloxane, modified dimethylsiloxane, polyethylene powder and the like, which are usually used as slipping agents.

(Formation of back coat layer)
The backcoat layer in the present invention is prepared by dissolving each component constituting the backcoat layer in a solvent to prepare a coating solution, and this coating solution is the surface opposite to the surface on which the recording layer is formed on the support (back surface). And it can form by apply | coating to the surface in which the above-mentioned anodized film was formed.

  As a solvent to be used, an organic solvent as described in JP-A-62-251739 can be used alone or in combination. Examples of the solvent include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxyethane, Examples include, but are not limited to, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and toluene. Is not to be done. These solvents are used alone or in combination.

  The lithographic printing plate precursor according to the present invention has a back coat layer provided on the back surface of the support together with the recording layer described above, so that even when laminated without using a slip sheet, a manufacturing process step, a plate making step, etc. In addition, it is possible to exhibit an excellent effect that the recording layer is not scratched or bonded to the recording layer even during transportation at the time of packaging or transportation after shipment as a product. That is, for example, even when a planographic printing plate precursor is laminated and packaged, packed, and transported, the surface on the recording layer side and the back surface in contact with the surface (the surface having the backcoat layer) are transported. The recording layer is not rubbed due to rubbing by the vibration. Further, even when the laminated plate material is stored for a long time in a high-humidity environment, an adhesive failure does not occur in the recording layer. In addition, even when the printing layer is used in an exposure apparatus equipped with an autoloader, the recording layer side surface and a part of the back surface are pressed and moved while being pressed. Will not occur.

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

  Among them, in the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10% by mass.

  Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements.

  Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

Such an aluminum plate may be subjected to surface treatment such as roughening treatment or anodizing treatment, if necessary. Hereinafter, such a surface treatment will be briefly described.

  Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used.

  The aluminum plate roughened as described above is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodizing treatment if desired in order to enhance the water retention and wear resistance of the surface. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm ^2. A voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable. When the amount of the anodized film is less than 1.0 g / m ² , the printing durability is insufficient, or the non-image portion of the planographic printing plate is easily damaged, and the ink adheres to the damaged portion during printing. There is a tendency that so-called “scratch dirt” is likely to occur.

After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary.
Examples of the hydrophilization treatment used in the present invention include US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There are alkali metal silicate (eg, aqueous sodium silicate) methods as disclosed.
In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and U.S. Pat. Nos. 3,276,868, 4,153,461, and 4,689,272. For example, a method of treating with polyvinylphosphonic acid as disclosed in JP-A No. 1993-133.

(Organic subbing layer)
In the lithographic printing plate precursor according to the invention, an organic undercoat layer can be provided between the support and the recording layer, if necessary.

  As the organic undercoat layer component, various organic compounds are used. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, and optionally substituted phenyl Organic phosphonic acids such as phosphonic acid, naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid, optionally substituted phenylphosphoric acid, naphthylphosphonic acid, alkylphosphoric acid and glyceroline Organic phosphoric acid such as acid, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, organic phosphinic acid such as alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and triethanolamine Hydroxy, such as hydrochloride -Alanine, and hydrochlorides of amines having a, may be used by mixing two or more.

  The organic undercoat layer preferably contains a compound having an onium group. The compounds having an onium group are described in detail in JP-A 2000-10292, JP-A 2000-108538, JP-A 2000-241962, and the like.

  Among them, preferred is at least one compound selected from the group of polymer compounds having a structural unit represented by poly (p-vinylbenzoic acid) in the molecule. Specific examples include a copolymer of p-vinylbenzoic acid and vinylbenzyltriethylammonium chloride, a copolymer of p-vinylbenzoic acid and vinylbenzyltrimethylammonium salt, and the like.

  The organic undercoat layer can be provided by the following method. That is, a method in which a solution obtained by dissolving the above organic compound in water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof is applied on an aluminum plate and dried, and water, methanol, ethanol, methyl ethyl ketone, etc. In this method, an aluminum plate is immersed in a solution obtained by dissolving the above organic compound in an organic solvent or a mixed solvent thereof to adsorb the above compound, and then washed with water and dried to provide an organic undercoat layer. . In the former method, a solution having a concentration of 0.005 to 10% by mass of the organic compound can be applied by various methods. In the latter method, the concentration of the solution is 0.01 to 20% by mass, preferably 0.05 to 5% by mass, the immersion temperature is 20 to 90 ° C., preferably 25 to 50 ° C., and the immersion time is 0.1 second to 20 minutes, preferably 2 seconds to 1 minute. The solution used for this can be adjusted to a pH range of 1 to 12 with basic substances such as ammonia, triethylamine, potassium hydroxide, and acidic substances such as hydrochloric acid and phosphoric acid. A yellow dye can also be added to improve the tone reproducibility of the recording layer.

The coating amount of the organic undercoat layer is suitably ² to 200 mg / m ² , preferably 5 to 100 mg / m ² . When the coating amount is in the above range, sufficient printing durability can be obtained.

  The infrared-sensitive lithographic printing plate produced as described above is imagewise exposed and then developed.

[Plate making]
The planographic printing plate precursor of the present invention is image-formed by heat. Specifically, direct image-like recording using a thermal recording head, scanning exposure using an infrared laser, high-illuminance flash exposure such as a xenon discharge lamp, infrared lamp exposure, etc. are used. Exposure with a solid high-power infrared laser such as a laser or YAG laser is preferred.

  The exposed lithographic printing plate precursor of the present invention is subjected to development processing and post-processing with a finisher, protective gum, or the like to form a printing plate. For these processes, a known processing apparatus such as an automatic processor can be used.

  The processing agent used in the development processing and post-processing of the lithographic printing plate precursor according to the invention can be appropriately selected from known processing agents.

  A suitable developer is a developer having a pH in the range of 9.0 to 14.0, preferably in the range of 12.0 to 13.5. A conventionally known alkaline aqueous solution can be used as the developer. Among the above alkaline aqueous solutions, as a particularly suitable developer, a so-called “silicate” well known in the art containing an alkali silicate as a base or containing an alkali silicate by mixing a silicon compound with a base. An aqueous solution called “developer” having a pH of 12 or higher, and non-reducing sugars (organic compounds having a buffering action) that do not contain an alkali silicate, as described in JP-A-8-305039 and JP-A-11-109637 And a so-called “non-silicate developer” containing an acid and a base.

  The developer preferably contains an anionic surfactant and / or an amphoteric surfactant from the viewpoint of promoting development and preventing wrinkles.

When the lithographic printing plate of the present invention is burned, it is preferably carried out by a conventionally known method using a burning surface-conditioning liquid and using a burning processor or the like.

  The lithographic printing plate obtained by such processing is applied to an offset printing machine or the like and used for printing a large number of sheets.

  Since the lithographic printing plate precursor according to the invention has the above-described configuration, even when the lithographic printing plate precursor is laminated without interleaving paper, the recording layer is effectively prevented from being damaged, so that the handling property is excellent.

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

[Synthesis Example 1: Synthesis of long-chain alkyl group-containing polymer A]
A 1000 ml three-necked flask equipped with a condenser and a stirrer was charged with 59 g of 1-methoxy-2-propanol and heated to 80 ° C. Under a nitrogen stream, a solution consisting of 42.0 g of n-stearyl methacrylate, 16.0 g of methacrylic acid, 0.714 g of a polymerization initiator V-601 (manufactured by Wako Pure Chemical Industries), and 59 g of 1-methoxy-2-propanol was used for 2 hours. It was dripped over half. Furthermore, it was made to react at 80 degreeC for 2 hours. The reaction mixture was cooled to room temperature and poured into 1000 ml of water. After decantation, the product was washed with methanol, and the obtained liquid product was dried under reduced pressure to obtain 73.5 g of (a) a long-chain alkyl group-containing polymer A shown below. The mass average molecular weight measured by gel permeation chromatography (GPC) using polystyrene as a standard substance was 66,000.

[Example 1]
(Production of support)
<Aluminum plate>
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.026 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: It contains 0.02% by mass, and the balance is prepared using Al and an inevitable impurity aluminum alloy. After the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Produced. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, it was kept soaked at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Furthermore, after performing heat processing using a continuous annealing machine at 500 degreeC, it finished by cold rolling to 0.24 mm in thickness, and obtained the aluminum plate of JIS1050 material. The obtained aluminum had an average crystal grain size with a minor axis of 50 μm and a major axis of 300 μm. After making this aluminum plate width 1030mm, it used for surface treatment.
For the surface treatment, the following various treatments (a) to (k) were continuously performed. In addition, after each process and water washing, the liquid was drained with the nip roller.

(A) Mechanical surface roughening treatment While supplying a suspension of a polishing agent (pumice) having a specific gravity of 1.12 and water as a polishing slurry liquid to the surface of the aluminum plate, mechanical roughening is performed by a rotating nylon brush. Surface treatment was performed. The average particle size of the abrasive was 30 μm, and the maximum particle size was 100 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 45 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkali etching treatment The aluminum plate obtained above was subjected to an etching treatment by spraying using an aqueous solution having a caustic soda concentration of 2.6% by mass, an aluminum ion concentration of 6.5% by mass and a temperature of 70 ° C. / M ² dissolved. Then, water washing by spraying was performed.

(C) Desmutting treatment The desmutting treatment was performed by spraying with a 1% by mass aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by mass of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a process of performing an electrochemical surface roughening treatment using alternating current in a nitric acid aqueous solution.

(D) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10.5 g / L aqueous solution of nitric acid (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions) at a liquid temperature of 50 ° C. An electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode, using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reached a peak and a duty ratio of 1: 1. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Then, water washing by spraying was performed.

(E) Alkaline etching treatment An aluminum plate was spray-etched at 32 ° C. using an aqueous solution having a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass, and the aluminum plate was dissolved at 0.50 g / m ² . Removes the smut component mainly composed of aluminum hydroxide that was generated when electrochemical roughening treatment was performed using the alternating current of the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

(F) Desmut treatment Desmut treatment by spraying was performed with a 15% by weight aqueous solution of sulfuric acid at a temperature of 30 ° C. (containing 4.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a process of performing an electrochemical surface roughening treatment using alternating current in a nitric acid aqueous solution.

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 5.0 g / L aqueous solution (containing 5 g / L of aluminum ions) at a temperature of 35 ° C. An electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode, using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reaches a peak from zero and a duty ratio of 1: 1. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. Then, water washing by spraying was performed.

(H) Alkaline etching treatment The aluminum plate was subjected to an etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass%, and the aluminum plate was dissolved at 0.10 g / m ² . Removes the smut component mainly composed of aluminum hydroxide that was generated when electrochemical roughening treatment was performed using the alternating current of the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

(I) A desmut treatment was performed by spraying with a 25% by weight aqueous solution of sulfuric acid having a desaturation temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

(J) Anodizing treatment Anodizing device of two-stage feeding electrolytic treatment method (first and second electrolytic section length 6 m each, first and second feeding section length 3 m each, first and second feeding electrode section length 2.4 m each) Anodizing was performed using this. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 50 g / L (containing 0.5 mass% of aluminum ions) and a temperature of 20 ° C. Then, water washing by spraying was performed. The final oxide film amount was 2.7 g / m ² .

(K) Alkali metal silicate treatment An alkali metal silicate is obtained by immersing the aluminum support obtained by anodizing treatment in a treatment tank of 1 mass% sodium silicate No. 3 aqueous solution at a temperature of 30 ° C. for 10 seconds. Processing (silicate processing) was performed. Then, the water washing by the spray using well water was performed and the aluminum support F by which the surface silicate hydrophilization process was carried out was obtained.

(Formation of back coat layer)
The following <Backcoat layer A> was provided on the back surface of the support obtained as described above.

<Backcoat layer A>
Back coating solution A having the following composition was applied by adjusting the wet amount with a bar coater so that the thickness after drying was 10 μm, and dried at 100 ° C. for 60 seconds.
-Backcoat liquid A-
M-cresol / p-cresol novolak resin (m / p = 6/4) 12 g
・ Surfactant (Fluorosurfactant B, structure below) 0.05g
・ Solvent: Methyl ethyl ketone / 1-methoxy-2-chlorophenol = 5/5 100g

<Formation of organic undercoat layer>
The following organic undercoat liquid was applied with a bar coater to the surface-treated surface of the support opposite to the surface on which the backcoat layer was formed, and dried at 80 ° C. for 15 seconds. An organic undercoat layer was provided so as to be m ² .

-Organic undercoat liquid-
・ The following polymer compound 0.3g
・ Methanol 100.0g
・ Water 1.0g

[Formation of recording layer]
On the aluminum support on which the organic undercoat layer was formed, the following recording layer coating solution 1 was coated with a bar coater so that the coating amount after drying was 0.85 g / m ^2, and then dried at 160 ° C. for 44 seconds. Then, the recording layer 1 (lower layer) was formed by immediately cooling with cold air of 17 to 20 ° C. until the temperature of the support became 35 ° C. Then, the following recording layer coating solution 2 was applied with a bar coater so that the coating amount after drying was 0.22 g / m ² , dried at 148 ° C. for 25 seconds, and further with wind of 20 to 26 ° C. The recording layer 2 (upper layer) was formed by slow cooling.
As described above, an infrared-sensitive lithographic printing plate precursor of Example 1 was obtained.

(Recording layer forming coating solution 1)
N- (4-aminosulfonylphenyl) methacrylamide /
Acrylonitrile / methyl methacrylate (36/34/30 wt%: weight average molecular weight 50000,
Acid value 2.65) 2.1 g
・ Cyanine dye A (the following structure) 0.13g
・ 4,4′-bishydroxyphenylsulfone 0.13 g
・ Cis-Δ ⁴ -tetrahydrophthalic anhydride 0.19 g
・ 0.008 g of p-toluenesulfonic acid
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.032 g
・ The ethyl violet counter ion is changed to 6-hydroxy-2-naphthalenesulfonic acid 0.078 g
・ Fluorosurfactant B (the above structure) 0.007 g
・ Methyl ethyl ketone 25.0g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-Butyrolactone 13.0g

(Recording layer forming coating solution 2)
-M, p-cresol novolak (m / p ratio = 6/4, weight average molecular weight 4500, containing 0.8% by mass of unreacted cresol, Tg 75 ° C.) 0.35 g
・ Acrylic resin C (structure below) 0.042g
・ Long chain alkyl group-containing polymer A 0.022 g
・ Cyanine dye A (the above structure) 0.019 g
-Ammonium compound D (the following structure) 0.004 g
・ Fluorosurfactant B (the above structure) 0.0045 g
・ Fluorosurfactant E (the following structure) 0.0033g
・ Methyl ethyl ketone 10.0g
1-methoxy-2-propanol 20.0g

[Example 2]
An infrared-sensitive lithographic printing plate precursor of Example 2 was obtained in the same manner as in Example 1 except that <Backcoat layer A> formed in Example 1 was changed to <Backcoat layer B> described below.

<Backcoat layer B>
A back coat liquid B having the following composition was applied by adjusting the wet amount with a bar coater so that the thickness after drying was 10 μm, and dried at 100 ° C. for 60 seconds.
-Backcoat liquid B-
・ Polystyrene 12g
・ Surfactant (Fluorosurfactant B, the above structure) 0.05 g
・ Solvent: Methyl ethyl ketone / 1-methoxy-2-chlorophenol = 5/5 100g

Example 3
An infrared-sensitive lithographic printing plate precursor of Example 3 was obtained in the same manner as in Example 1 except that <Backcoat layer A> formed in Example 1 was changed to <Backcoat layer C> described below.

<Backcoat layer C>
Back coating solution C having the following composition was applied by adjusting the wet amount with a bar coater so that the thickness after drying was 10 μm, and dried at 100 ° C. for 60 seconds.
-Backcoat liquid C-
・ Saturated polymerized polyester resin (Chemit K-588, manufactured by Toray Industries, Inc.) 12g
・ Surfactant (Fluorosurfactant B, the above structure) 0.05 g
・ Solvent: methyl ethyl ketone / 1-methoxy-2-chlorophenol = 7/3 100 g

Example 4
An infrared-sensitive lithographic printing plate precursor of Example 4 was obtained in the same manner as in Example 1 except that <Backcoat layer A> formed in Example 1 was changed to <Backcoat layer D> described below.

<Backcoat layer D>
A back coat liquid D having the following composition was applied by adjusting the wet amount with a bar coater so that the thickness after drying was 10 μm, and dried at 100 ° C. for 60 seconds.
-Backcoat liquid D-
・ Phenoxy resin (Phenato YP-50, manufactured by Tokyo Chemical Industry Co., Ltd.) 12g
・ Surfactant (Fluorosurfactant B, the above structure) 0.05 g
・ Solvent: methyl ethyl ketone / 1-methoxy-2-chlorophenol = 7/3 100 g

Example 5
An infrared-sensitive lithographic printing plate precursor of Example 5 was obtained in the same manner as in Example 1 except that <Backcoat layer A> formed in Example 1 was changed to <Backcoat layer F> described below.

<Backcoat layer E>
A back coat solution E having the following composition was applied by adjusting the wet amount with a bar coater so that the thickness after drying was 10 μm, and dried at 100 ° C. for 60 seconds.
-Backcoat liquid E-
-Polyvinyl butyral resin (Denka Butyral 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.) 12g
・ Surfactant (Fluorosurfactant B, the above structure) 0.05 g
・ Solvent: methyl ethyl ketone / 1-methoxy-2-chlorophenol = 7/3 100 g

Example 6
An infrared-sensitive lithographic printing plate precursor of Example 6 was obtained in the same manner as in Example 1 except that <Backcoat layer A> formed in Example 1 was changed to <Backcoat layer E> described below.

<Backcoat layer E>
A back coat solution E having the following composition was applied by adjusting the wet amount with a bar coater so that the thickness after drying was 10 μm, and dried at 100 ° C. for 60 seconds.
-Backcoat liquid E-
・ Vinylidene chloride-acrylonitrile copolymer resin (Saran F-310, manufactured by Asahi Dow Co., Ltd.) 12g
・ Surfactant (Fluorosurfactant B, the above structure) 0.05 g
・ Solvent (Methyl ethyl ketone / 1-methoxy-2-chlorophenol = 7/3) 100g

Example 7
An infrared-sensitive lithographic printing plate precursor of Example 7 was obtained in the same manner as in Example 3 except that the thickness of <Backcoat Layer C> formed in Example 3 was changed from 10 μm to 1 μm.

Example 8
An infrared-sensitive lithographic printing plate precursor of Example 8 was obtained in the same manner as in Example 3 except that the thickness of <Backcoat Layer C> formed in Example 3 was changed from 10 μm to 20 μm.

[Comparative Example 1]
In Example 1, the coating liquid 2 for forming the recording layer used for forming the recording layer 2 (upper layer) does not contain the long chain alkyl group-containing polymer A, and no <back coat layer A> is formed. Except that, an infrared-sensitive lithographic printing plate precursor of Comparative Example 1 was obtained in the same manner as Example 1.

[Comparative Example 2]
In Example 3, the recording layer forming coating solution 2 used for forming the recording layer 2 (upper layer) does not contain the long-chain alkyl group-containing polymer A, and the thickness of the <back coat layer C> is 10 μm. The infrared-sensitive lithographic printing plate precursor of Comparative Example 2 was obtained in the same manner as in Example 3 except that the thickness was changed from 0.2 to 0.2 μm.

[Comparative Example 3]
An infrared-sensitive lithographic printing plate precursor of Comparative Example 3 was obtained in the same manner as in Example 3 except that the thickness of <Backcoat layer C> was changed from 10 μm to 0.2 μm in Example 3.

[Comparative Example 4]
In Example 1, the recording layer forming coating solution 2 used for forming the recording layer 2 (upper layer) does not contain the long-chain alkyl group-containing polymer A, and further, <Backcoat layer A> is not formed. In addition, the infrared light-sensitive material of Comparative Example 4 was prepared in the same manner as in Example 1 except that an aqueous copolymerized polymer solution having the following composition was applied at a solid content of 20% with an electrostatic air type spray and dried at 60 ° C for 5 seconds. A sex lithographic printing plate precursor was obtained.
-Copolymer composition of Comparative Example 4-
・ Methyl methacrylate 68% by mass
・ Ethyl acrylate 20% by mass
・ Sodium acrylate 12% by mass

[Comparative Example 5]
In Example 1, the recording layer forming coating solution 2 used for forming the recording layer 2 (upper layer) did not contain the long-chain alkyl group-containing polymer A, and was further used for forming <Backcoat Layer A>. An infrared-sensitive lithographic printing plate precursor of Comparative Example 5 was obtained in the same manner as in Example 1 except that the <Backcoat layer F> was formed using the following backcoat solution F instead of the backcoat solution A.
-Backcoat fluid F-
・ Styrene / methyl methacrylate copolymer 10g
・ Silica gel (particle size 4μm) 4g
・ Solvent: 100g of methyl ethyl ketone

  Table 1 below shows the types of organic polymers and the like contained in the backcoat layer, the thickness (μm) of the backcoat layer, and the presence or absence of a long-chain alkyl group-containing polymer in the recording layer in Examples and Comparative Examples. Are described together.

<Evaluation>
For the obtained infrared-sensitive lithographic printing plate precursors of Examples 1 to 8 and Comparative Examples 1 to 5, "1. Generation of scratches by transportation", "2. Adhesiveness under high humidity conditions", "3 Each item of “Generation of scratches by autoloader” was evaluated.

1. Evaluation of generation of scratches due to transportation Each of the obtained infrared-sensitive lithographic printing plate precursors was cut into 1030 mm × 800 mm to prepare 30 sheets each. The 30 sheets were stacked without interleaving paper, one piece of cardboard with a thickness of 0.5 mm was placed on the top and bottom, taped at the four corners, and then wrapped with aluminum kraft paper. This was further packaged with a cardboard case and taped to make an interleaf-free packaging form. This was placed on a pallet, transported 2000 km by truck, and then opened. The unsealed infrared-sensitive lithographic printing plate precursor is charged into Fuji Photo Film Co., Ltd. automatic developing machine LP-940HII with Fuji Photo Film Co., Ltd. developer DT-2 at a development ratio of 1: 8. The development process was performed at a temperature of 12 ° C. for 12 seconds. The electric conductivity of the developer at this time was 43 mS / cm. The developed lithographic printing plate was visually observed and evaluated for the presence or absence of missing image portions due to transportation.
A case where there is no omission in the image portion is indicated by “◯”, and a case where an omission in the image portion is present is indicated by “X”. The results are shown in Table 4.

2. Evaluation of adhesiveness under high humidity conditions In the summer (July degree), the lithographic printing plate precursor of the same size as above was put on top of each other without putting interleaving paper, and iron batting plates were placed on top and bottom and bolted. ) In the warehouse for one month. Thereafter, the bolts were removed and the presence or absence of adhesion between the lithographic printing plate precursors was evaluated.
“○” indicates that there was no adhesion, and “X” indicates that there was adhesion. The results are shown in Table 4.

3. Evaluation of generation of scratches in the autoloader After 10 lithographic printing plate precursors having the same size as above were set in a Luxel T-9800CTP single autoloader cassette without inserting slip sheets, the plate was automatically fed and the drum was mounted. Unexposed, unloaded, and developed into Fuji Photo Film Co., Ltd. automatic developing machine LP-940HII, Fuji Photo Film Co., Ltd. developer DT-2 (diluted 1: 8) and Fuji Photo Film Co., Ltd. Finisher FG-1 (diluted 1: 1) was charged and developed at a development temperature of 32 ° C. and a development time of 12 seconds. The electric power of the developer at this time was 43 mS / cm. The developed lithographic printing plate was visually observed to evaluate the occurrence of scratches caused by loading and unloading.
The case where no scratch was generated is indicated by “◯”, and the case where the scratch was generated is indicated by “X”. The results are shown in Table 4.

  As shown in Table 2, the infrared-sensitive lithographic printing plates of the examples were excellent in transportability and storage suitability even when they were stacked and packed without interleaving paper, and equipped with an autoloader. It can be seen that the lithographic printing plate precursor is also excellent in suitability for the exposure apparatus.

Claims (2)

  One side of the support has a recording layer containing a water-insoluble and alkali-soluble resin, an infrared absorber, and a long-chain alkyl group-containing polymer and capable of forming an image by infrared irradiation. An infrared-sensitive lithographic printing plate precursor comprising a backcoat layer containing an organic polymer and having a thickness of 0.3 μm or more on the surface opposite to the surface having the surface. A multilayer structure capable of forming an image by infrared irradiation including a lower layer containing a water-insoluble and alkali-soluble resin and a top layer containing a water-insoluble and alkali-soluble resin and a long-chain alkyl group-containing polymer on one side of the support And at least one of the lower layer and the uppermost layer is a layer containing an infrared absorber,
An infrared-sensitive lithographic printing plate precursor comprising a back coat layer containing an organic polymer and having a thickness of 0.3 μm or more on the surface opposite to the surface having the recording layer of the support.