JP2009069384A - Photosensitive planographic printing precursor for ir laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive planographic printing plate precursor for an IR laser, the precursor being excellent in both of chemical resistance and scratch resistance. <P>SOLUTION: The photosensitive planographic printing plate precursor for an IR laser includes a lower layer containing a polymer compound having a phenolic hydroxyl group and a group expressed by general formula (1) or general formula (2) in a side chain and an IR ray absorbent, and an upper layer containing a water-insoluble and alkali-soluble resin, in this order on a support body having a hydrophilic surface. In the general formula (1) or in the formula (2), R represents a 1-12C alkyl group, a 6-15C aryl group or a 2-12C alkenyl group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photosensitive lithographic printing plate precursor for infrared laser, and more specifically, a so-called direct lithographic photosensitive lithographic plate capable of direct plate making by scanning infrared laser light based on a digital signal of a computer or the like. It relates to the printing plate precursor.

  In recent years, the development of lasers has been remarkable, and in particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared region have been increasing in output and size. Therefore, these lasers are very useful as an exposure light source when making a plate directly from digital data such as a computer.

  Infrared laser lithographic printing plate precursors that use an infrared laser having a light emitting region in the infrared region as an exposure light source generally contain a binder resin and an IR dye that absorbs light and generates heat as essential components. is there. Among such lithographic printing plate precursors for infrared lasers, those having a positive recording layer, when exposed to infrared laser, the IR dye and the like in the recording layer in the unexposed area (image area) By interacting, it acts as a dissolution inhibitor that substantially reduces the solubility of the binder resin. On the other hand, in the exposed portion (non-image portion), the IR dye or the like absorbs light and generates heat, so that the interaction between the IR dye and the binder resin is weakened. Therefore, at the time of development, the exposed portion (non-image portion) is dissolved and removed in an alkaline developer, whereby a lithographic printing plate is obtained.

In such a lithographic printing plate precursor for infrared laser, improvement in chemical resistance and improvement in scratch resistance are cited as technical problems. Among these, for improving chemical resistance, for example, it has been proposed to use polyvinyl acetal (see, for example, Patent Document 1), but this is insufficient from the viewpoint of achieving both chemical resistance and scratch resistance. In addition, it is considered that the resin layer structure of a lithographic printing plate precursor having two or more layers is useful for achieving both chemical resistance and scratch resistance. For example, a polymer having a maleimide compound as a constituent component in a lower layer Although it has been proposed to use a compound (see, for example, Patent Document 2), further level-up has been desired.
US Published Patent No. 2004/0020484 US Published Patent No. 2004/0067432

  An object of the present invention is to provide a photosensitive lithographic printing plate precursor for infrared laser which is excellent in both chemical resistance and scratch resistance.

  As a result of diligent research, the present inventor has found that the above problems can be solved by the following photosensitive lithographic printing plate precursor for infrared laser, and has completed the present invention.

  That is, the photosensitive lithographic printing plate precursor for infrared laser of the present invention has a phenolic hydroxyl group on a support having a hydrophilic surface and a group represented by the following general formula (1) or the following general formula (2). It is characterized by having in this order a lower layer containing a polymer compound having a side chain and an infrared absorber, and an upper layer containing a water-insoluble and alkali-soluble resin.

  In General Formula (1) or General Formula (2), R represents an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 15 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms.

  Here, “having in this order” means that at least the lower layer and the upper layer are provided in this order on a support having a hydrophilic surface, and other layers (for example, undercoat) provided as desired. It does not deny the existence of a layer.

  ADVANTAGE OF THE INVENTION According to this invention, the photosensitive lithographic printing plate precursor for infrared lasers excellent in both chemical resistance and scratch resistance can be provided.

[Photosensitive lithographic printing plate precursor for infrared laser]
Hereinafter, the photosensitive lithographic printing plate precursor for infrared laser of the present invention will be described in detail.
The photosensitive lithographic printing plate precursor for infrared laser of the present invention (hereinafter sometimes simply referred to as “lithographic printing plate precursor”) has a phenolic hydroxyl group on a support having a hydrophilic surface and the following general formula. (1) or a polymer compound having a group represented by the following general formula (2) in the side chain (hereinafter sometimes simply referred to as “specific polymer compound”), and a lower layer containing an infrared absorber; And an upper layer containing a water-insoluble and alkali-soluble resin in this order.

  In General Formula (1) or General Formula (2), R represents an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 15 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms.

  The lithographic printing plate precursor according to the invention exhibits an excellent effect in both chemical resistance and scratch resistance by having the above-described configuration. The reason for this is not yet clear, but the improvement in chemical resistance in the present invention is achieved by containing a specific polymer compound in the lower layer and further providing an upper layer covering the lower layer, thereby slowing the penetration of the solvent. Presumably because it was made. For improving scratch resistance, the recording layer of the lithographic printing plate precursor according to the present invention is composed of two or more resin layers, and a high-strength film can be formed in the lower layer of the resin layer. It is presumed that the strength of the entire resin layer was increased by including such a specific polymer compound. Hereafter, each element which comprises the lithographic printing plate precursor of this invention is demonstrated sequentially.

[Lower layer containing specific polymer compound and infrared absorber]
The lower layer in the lithographic printing plate precursor according to the invention is a layer provided closer to the support than the upper layer described later, and contains a specific polymer compound and an infrared absorber.

(Specific polymer compound)
The specific polymer compound in the present invention is a polymer compound having a phenolic hydroxyl group and having a group represented by the following general formula (1) or the following general formula (2) in the side chain.

  In General Formula (1) or General Formula (2), R represents an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 15 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms.

  When R is an alkyl group having 1 to 12 carbon atoms, an alkyl group having 3 to 9 carbon atoms is preferable, and a t-butyl group is particularly preferable.

  In addition, the alkyl group represented by R may be an aryl-substituted alkyl group, and suitable examples thereof include phenylmethyl group, 1-phenylethyl group, 2-phenylethyl group, 1-methyl- Examples thereof include 2-phenylethyl group and 1,1-dimethyl-2-phenylethyl group.

When R is an aryl group having 6 to 15 carbon atoms, it is preferably a phenyl group or a naphthyl group, and particularly preferably a phenyl group.
Further, as the phenyl group or naphthyl group represented by R, an alkyl-substituted phenyl group or naphthyl group is also suitable, and specific examples thereof include a p-methylphenyl group and a pt-butylphenyl group. Can be mentioned.

  When R is an alkenyl group having 2 to 12 carbon atoms, an alkenyl group having 3 to 9 carbon atoms is preferable, and suitable examples thereof include 2-propenyl group, 1-methyl-2-propenyl group, 4-butenyl group and the like. Can be mentioned.

  As for the group shown by general formula (1) or general formula (2), only 1 type may be contained in the same molecule, and 2 or more types may be contained.

  Further, the specific polymer compound contains either one of the groups represented by the general formula (1) and the general formula (2) in the molecule, but may contain both.

  The group represented by the general formula (1) can be obtained by reacting a carbonate compound with a compound having a hydroxyl group. Further, the group represented by the general formula (2) can be obtained by reacting a compound having a hydroxyl group with an isocyanate compound.

  In the specific polymer compound, examples of the main chain having a side chain having the group represented by the general formula (1) or the general formula (2) include vinyl resins and phenol resins, and are vinyl resins. Among them, styrene resins are particularly preferable.

  The specific polymer compound has a phenolic hydroxyl group. The phenolic hydroxyl group may be introduced into either the main chain or the side chain in the specific polymer compound.

  When the main chain of the specific polymer compound is a vinyl resin, for example, it is possible to use a monomer having a phenolic hydroxyl group such as p-hydroxystyrene or p-hydroxyphenyl-oxyethyl methacrylate. It is suitable as a mode of introducing a phenolic hydroxyl group into a compound. Thereby, a specific high molecular compound has a phenolic hydroxyl group in the side chain.

  When the main chain of the specific polymer compound is a phenolic resin, the resin itself has a phenolic hydroxyl group. As such a phenol resin, a resin containing phenol or cresol is preferable.

  In the specific polymer compound, the content ratio of the phenolic hydroxyl group to the groups represented by the general formulas (1) and (2) is preferably in the range of 1: 0.05 to 1: 2, particularly preferably 1: 0. The range is from 1: 1 to 1: 1. The content ratio between the phenolic hydroxyl group and the groups represented by the general formulas (1) and (2) is within the above range, so that the chemical resistance resulting from the groups represented by the general formulas (1) and (2) and Both the effect of improving the scratch resistance and the solubility of the exposed area in the developer can be exhibited more remarkably.

  The specific polymer compound may have other components. In particular, when the main chain of the specific polymer compound is a vinyl resin, other components can be easily introduced by copolymerization.

  Other constituent components include monomers that can be copolymerized with the phenolic hydroxyl group that is an essential constituent element of the specific polymer compound and the monomer used to introduce the group represented by formula (1) or (2). If it is, it will not specifically limit. Examples of such monomers are preferably vinyl acetate, vinyl alcohol, styrene, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylonitrile, and the like.

  When the specific polymer compound has other constituent components, the ratio of the other constituent components in the specific polymer compound is preferably 50 mol% or less.

  Hereinafter, polymer compounds (1) to (6) which are exemplary compounds of the specific polymer compound will be listed, but the specific polymer compound in the present invention is not limited thereto. In addition, a, b, and c described in each specific example represent copolymerization molar ratios.

  As a weight average molecular weight of a specific molecular compound, 1000 or more are preferable and 1000-300000 are more preferable.

  Only 1 type may be sufficient as the specific molecular compound contained in a lower layer, and it may use 2 or more types together.

  It is preferable that a specific high molecular compound is contained in the ratio of 10-99 mass% in the total solid contained in a lower layer.

  In addition, when a specific high molecular compound is contained in the lower layer in the ratio of 10-30 mass%, it is preferable to use together the other high molecular compound mentioned later with a specific high molecular compound from the point of film property.

(Infrared absorber)
The lower layer in the present invention contains an infrared absorber.
The infrared absorber used here is not particularly limited as long as it is a dye having an absorption maximum from a wavelength of 750 nm to 1,400 nm and absorbing light of this wavelength and generating heat, and is known as an infrared absorbing dye. Various dyes can be used.

  As the infrared absorber in the present invention, commercially available dyes and known ones described in the literature (for example, “Dye Handbook” edited by Organic Synthetic Chemistry Association, 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.

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Furthermore, cyanine dyes are particularly preferred. Specific examples of cyanine dyes that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969.

  It is preferable that an infrared absorber is contained in 0.01-50 mass% in the total solid of a lower layer, More preferably, it is 0.1-30 mass%, Most preferably, it is 1.0-30 mass%. There is a ratio.

(Other polymer compounds)
In the lower layer in the present invention, in addition to the specific polymer compound described above, other polymer compounds can be used in combination. The polymer compound used in combination may be one type or two or more types. Moreover, although a high molecular compound is used for the upper layer, two or more types of high molecular compounds may be used. Here, these polymer compounds are described.

  Other polymer compounds that can be used in the present invention are preferably polymer compounds that are soluble or swellable in an alkaline aqueous solution. Such a high molecular compound is a high molecular compound different from the specific high molecular compound, and has an acidic group listed in (1) to (6) below in the main chain and / or side chain of the polymer. Mention may be made of molecular compounds.

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

In the acidic groups listed as (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R ^A is a hydrocarbon group which may have a substituent. Represents.

  Examples of the polymer compound having an acidic group selected from (1) to (6) include the following.

  (1) Examples of the polymer compound having a phenol group include novolak resins, xylenol resins, and resole resins. Specifically, phenol formaldehyde resins, m-cresol formaldehyde resins, p-cresol formaldehyde resins, m // p-mixed cresol formaldehyde resin, phenol / cresol (m-, p-, o-, m- / p-mixed, m- / o-mixed and o- / p-mixed) mixed formaldehyde resin, 1,2-xylenol, 1,3-xylenol, 1,4-xylenol, 1,5-xylenol, 2,3-xylenol, 2,4-xylenol resin, xylenol / phenol mixed resin, xylenol / novolak mixed resin, xylenol / Novolac / Phenol mixed resin and Pi Mention may be made of the condensation polymers of Garoru and acetone. In addition, a polymer compound obtained by copolymerizing a compound having a phenol group in the side chain can also be mentioned, and acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, or hydroxystyrene having a phenol group can be used as a copolymer component. High molecular compounds.

  (2) As a polymer compound having a sulfonamide group, for example, a polymer composed of a minimum structural unit derived from a compound having a sulfonamide group as a main constituent can be mentioned. Examples of such compounds include compounds having at least one sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom and one or more polymerizable unsaturated groups in the molecule. Sulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) acrylamide and the like can be suitably used.

  (3) As a high molecular compound which has an active imide group, the polymer comprised as a main structural component the minimum structural unit derived from the compound which has an active imide group can be mentioned, for example. Examples of the compound as described above include compounds having one or more active imide groups represented by the following structural formula and polymerizable unsaturated groups in the molecule, respectively. N- (p-toluenesulfonyl) ) Methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

(4) As a high molecular compound having a carboxylic acid group, for example, a minimum structural unit derived from a compound having at least one carboxylic acid group and one or more polymerizable unsaturated groups in the molecule is used as a main constituent component. A polymer can be mentioned. Acrylic acid, methacrylic acid, maleic acid, and itaconic acid can be particularly preferably used in the multilayer sensitive material type printing plate precursor of the present invention.
(5) As a high molecular compound having a sulfonic acid group, for example, a minimum structural unit derived from a compound having at least one sulfonic acid group and polymerizable unsaturated group in the molecule is used as a main structural unit. A polymer can be mentioned.
(6) As a high molecular compound having a phosphoric acid group, for example, a minimum structural unit derived from a compound having at least one phosphoric acid group and a polymerizable unsaturated group in the molecule is used as a main constituent component. A polymer can be mentioned.

  In addition to the above, a polymer using an unsaturated compound having an acidic group of (1) to (6) in the side chain and a urea bond as a linking group can also be used.

  Among the polymer compounds having an acidic group selected from (1) to (6), a polymer having (1) a phenol group, (2) a sulfonamide group, (3) an active imide group, and (4) a carboxylic acid group. A compound is preferred, and in particular, a polymer compound having (1) a phenol group, (2) a sulfonamide group or (4) a carboxylic acid group is most preferred.

  Further, the minimum structural unit having an acidic group selected from (1) to (6) is not particularly limited to one kind, and two or more minimum structural units having the same acidic group are used, or different acidic groups are used. What copolymerized 2 or more types of the minimum structural unit which has can also be used.

  In the case where the polymer compound is a copolymer, it is preferable that a compound having an acidic group selected from (1) to (6) to be copolymerized is contained in an amount of 3 mol% or more in the copolymer. % Is more preferable.

  As described above, among the other polymer compounds mentioned as examples, the other polymer compound used in combination with the specific polymer compound in the lower layer is preferably a copolymer having a sulfonamide group and / or a carboxylic acid group. Examples of the copolymer component include alkyl (meth) acrylate, (meth) acrylamide, (meth) acrylonitrile, and N-phenylmaleimide.

  Further, as other polymer compounds, novolak resins are also preferably used, such as phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (m- , P-, o-, m- / p-mixed, m- / o-mixed and o- / p-mixed)) mixed formaldehyde resins. Two or more kinds of other polymer compounds may be used in combination.

  In the present invention, when the other polymer compound is a resin such as phenol formaldehyde resin or cresol aldehyde resin, the weight average molecular weight is 500 to 20,000, and the number average molecular weight is 200 to 10,000. Those are preferred. When the other polymer compound is other polymer compound, the weight average molecular weight is preferably 2,000 or more and the number average molecular weight is 500 or more, more preferably the weight average molecular weight is 5,000 to It is preferably 300,000, a number average molecular weight of 800 to 250,000 and a dispersity (weight average molecular weight / number average molecular weight) of 1.1 to 10.

  In the present invention, the total content of the polymer compound (specific polymer compound and other polymer compounds) contained in the lower layer is 30 to 99% by mass, preferably from the viewpoint of durability and sensitivity of the recording layer. It is 50-99 mass%, Most preferably, it is the range of 65-99 mass%.

(Other ingredients)
Various additives can be further added to the lower layer as necessary.
For example, in order to adjust the solubility of the lower layer, it is preferable to add a dissolution inhibitor such as onium salt, aromatic sulfone compound, aromatic sulfonic acid ester compound, polyfunctional amine compound, etc. -The use of a substance that is thermally decomposable, such as a quinonediazide compound and a sulfonic acid alkyl ester, and that substantially reduces the solubility of the alkali-soluble resin in a state where it does not decompose can prevent the dissolution of the image area in the developer. It is preferable in that it can be controlled. As the onium salt, a diazonium salt and a quaternary ammonium salt are particularly preferable.

  In addition, a dissolution inhibitor having no decomposability may be used in combination, such as sulfonic acid ester, phosphoric acid ester, aromatic carboxylic acid ester, aromatic disulfone, carboxylic acid anhydride, aromatic ketone, aromatic aldehyde, aromatic Examples thereof include amines and aromatic ethers.

  Furthermore, for the purpose of improving sensitivity, cyclic acid anhydrides, phenols, and organic acids can be used in the lower layer in combination with a surfactant, an image colorant, and a visible image immediately after heating by exposure. Bake-out agents and plasticizers can also be used.

Formation of a lower layer can be formed by dissolving each component which forms a lower layer in a solvent, and apply | coating on a suitable support body. Solvents that can be used 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 concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass.

Coating an upper layer coating solution on the support, the solid coating amount of the lower layer obtained after drying is preferably ^{0.3g / m 2 ~5.0g / m 2} , more preferably 0.5 g / m ² It is the range of -3.0 g / m < ² >.
Moreover, 0.05-1 are preferable and, as for ratio of the coating amount of an upper layer and a lower layer, More preferably, it is the range of 0.1-0.8.

  Various methods can be used as a method of applying the lower layer coating solution on the support, such as bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, Examples thereof include roll coating.

[Upper layer containing water-insoluble and alkali-soluble resin]
The upper layer in the present invention is characterized by containing a water-insoluble and alkali-soluble resin (hereinafter, appropriately referred to as “alkali-soluble resin”). Hereafter, each component which the upper layer in this invention contains is demonstrated.

(Water-insoluble and alkali-soluble resin)
The alkali-soluble resin that can be used for the upper layer is not particularly limited as long as it has a property of dissolving when contacted with an alkaline developer, but a monomer containing an acidic group in the main chain and / or side chain in the polymer. Is preferably a homopolymer obtained from the above, a copolymer thereof, or a mixture thereof.

  As such an alkali-soluble resin having an acidic group, in particular, a polymer compound having a functional group in any one of (1) a phenolic hydroxyl group, (2) a sulfonamide group, and (3) an active imide group. Can be mentioned. For example, although the following are illustrated, this 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 include novolak resins such as mixed formaldehyde resins and pyrogallol acetone resins. In addition to this, a polymer compound having a phenolic hydroxyl group in the side chain is preferably used as the polymer compound having a phenolic hydroxyl group. 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 phenolic hydroxyl group and at least one polymerizable unsaturated bond is homopolymerized, or other polymerization is performed on the monomer. And a high molecular compound obtained by copolymerizing a functional monomer.

  Examples of the polymerizable monomer having a phenolic hydroxyl group include acrylamide, methacrylamide, acrylic ester, methacrylic 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-hydroxy Phenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (2-hydroxyphenyl) ethyl acrylate, 2- (3-hydroxyphenyl) Preferable are til acrylate, 2- (4-hydroxyphenyl) ethyl acrylate, 2- (2-hydroxyphenyl) ethyl methacrylate, 2- (3-hydroxyphenyl) ethyl methacrylate, 2- (4-hydroxyphenyl) ethyl methacrylate, etc. Can be used. Such resins having a phenolic hydroxyl group may be used in combination of two or more. Furthermore, as described in U.S. Pat. No. 4,123,279, phenol and formaldehyde having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin, These copolymers may be used in combination.

(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 these, 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.

(3) The alkali-soluble resin having an active imide group is preferably one having an active imide group in the molecule, and the polymer compound has one unsaturated bond polymerizable with the active imide group in each molecule. Examples thereof include a polymer compound obtained by homopolymerizing a polymerizable monomer comprising the above-described low molecular weight compound, or copolymerizing the monomer with another polymerizable monomer.
As such a compound, specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

  The alkali-soluble resin contained in the upper layer is a polymer compound obtained by polymerizing two or more of a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group, and a polymerizable monomer having an active imide group. Preferably there is. Although there is no restriction | limiting in the copolymerization ratio of the said polymerizable monomer, and the combination of a polymerizable monomer, Especially the polymerizable monomer which has a sulfonamide group in the polymerizable monomer which has a phenolic hydroxyl group, and / or the polymerizable property which has an active imide group When monomers are copolymerized, the compounding polymerization ratio of these components is preferably in the range of 50:50 to 5:95, and particularly preferably in the range of 40:60 to 10:90.

  Furthermore, as the alkali-soluble resin contained in the upper layer, one or more kinds selected from a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group, or a polymerizable monomer having an active imide group are used. In addition to the polymerizable monomer, a polymer compound obtained by copolymerizing another polymerizable monomer is preferable. As a copolymerization ratio in this case, it is preferable that the monomer which provides alkali solubility is contained 10 mol% or more, and what contains 20 mol% or more is more preferable. When the copolymerization component of the monomer that imparts alkali solubility is less than 10 mol%, alkali solubility tends to be insufficient, and the development latitude tends to decrease.

  When the alkali-soluble resin contained in the upper layer is a homopolymer or copolymer of a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group, or a polymerizable monomer having an active imide group, the weight average molecular weight Are preferably 2,000 or more and a number average molecular weight of 500 or more. More preferably, the weight average molecular weight is 5,000 to 300,000, the number average molecular weight is 800 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10. .

  In particular, when the alkali-soluble resin contained in the upper layer is a phenol formaldehyde resin or a cresol aldehyde resin, the weight average molecular weight is 500 to 20,000, and the number average molecular weight is 200 to 10,000. Is preferred.

  As the alkali-soluble resin contained in the upper layer, a resin having a phenolic hydroxyl group is desirable in terms of causing strong hydrogen bonding in the unexposed area and easily releasing some hydrogen bonds in the exposed area. Among the resins having a functional hydroxyl group, a novolak resin is particularly preferable. In the present invention, two or more kinds of alkali-soluble resins having different dissolution rates in an alkaline aqueous solution may be mixed and used, and the mixing ratio in that case is arbitrary. The alkali-soluble resin suitable for mixing with the resin having a phenolic hydroxyl group is preferably an acrylic resin because of its low compatibility with a resin having a phenolic hydroxyl group, and more preferably a sulfoamide group. It is an acrylic resin.

  The content of the alkali-soluble resin in the total solid content of the upper layer is preferably in the range of 50 to 98% by mass from the viewpoint of the sensitivity and durability of the recording layer. In addition, this content points out the total amount, when using together multiple types of alkali-soluble resin.

  An infrared absorber can be added to the upper layer. The infrared absorber is not particularly limited as long as it has an absorption maximum from a wavelength of 750 nm to 1,400 nm and absorbs light of this wavelength and generates heat, and various dyes known as infrared absorbing dyes can be used. Specifically, the same materials as those mentioned as the infrared absorber used in the lower layer can be used.

  As content of the infrared absorber in an upper layer, it is preferable that it is 0.01-50 mass% in the total solid of an upper layer, More preferably, it is 0.1-30 mass%, Most preferably, it is 1.0-30. It is the range of mass%. By setting it in the above range, the sensitivity becomes better, and the uniformity and durability of the upper layer (upper recording layer) become better.

  The upper layer preferably contains a development inhibitor for the purpose of increasing its inhibition (dissolution inhibiting ability).

  As a development inhibitor, it forms an interaction with the alkali-soluble resin contained in the upper layer, substantially lowers the solubility of the alkali-soluble resin in the developer in the unexposed area, and in the exposed area There is no particular limitation as long as the interaction is weakened and can be soluble in the developer, but quaternary ammonium salts, polyethylene glycol compounds and the like are particularly preferably used. In addition, when the compound which has a function of a development inhibitor is used as an infrared absorber, it is not necessary to add a development inhibitor.

  Examples of quaternary ammonium salts include tetraalkylammonium salts, trialkylarylammonium salts, dialkyldiarylammonium salts, alkyltriarylammonium salts, tetraarylammonium salts, cyclic ammonium salts, and bicyclic ammonium salts. Polyethylene glycol compounds include polyethylene glycols, polypropylene glycols, polyethylene glycol alkyl ethers, polypropylene glycol alkyl ethers, polyethylene glycol aryl ethers, polypropylene glycol aryl ethers, polyethylene glycol alkyl aryl ethers, polypropylene glycol alkyl. Aryl ethers, polyethylene glycol glycerol esters, polypropylene glycol glycerol esters, polyethylene sorbitol esters, polypropylene glycol sorbitol esters, polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyethylene glycolated ethylenediamine , Polypropylene glycolated ethylenediamines, polyethylene glycolated diethylenetriamine, and polypropylene glycol diethylenetriamines.

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

  Examples of onium salts that can be used in the present invention include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, arsonium salts, and the like, and among these, diazonium salts are particularly preferable. Particularly suitable diazonium salts include those described in JP-A-5-158230.

Suitable quinonediazides include o-quinonediazide compounds.
The amount of these added is preferably in the range of 0.1 to 10% by mass, and more preferably in the range of 0.5 to 5% by mass in the total solid content of the upper layer.

  In forming the upper layer, in addition to the above-described components, various additives can be added as long as the effects of the present invention are not impaired.

  For example, acid anhydrides, phenols, and organic acids may be added for the purpose of improving sensitivity, and nonionic surfactants and amphoteric surfactants are used to improve coatability and improve processing stability against development conditions. Agents, siloxane compounds, and fluorine-containing monomer copolymers can be added. Baking agents for obtaining a visible image immediately after heating by exposure and dyes and pigments as image colorants can be added. Further, a plasticizer may be added to impart flexibility and the like of the coating film.

  The upper layer can usually be formed by dissolving the above components in a solvent and coating, but preferably the one that does not dissolve the lower layer as much as possible. 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 Mention may be made of ethane, methyl lactate, ethyl lactate, toluene and the like. These solvents are used alone or in combination.

Further, the coating amount of the upper layer obtained after coating and drying the upper layer coating solution on the support is preferably in the range of 0.05 to 2.0 g / m ² , more preferably 0.8. The range is 1 to 1.0 g / m ² .

[Support]
The support in the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like material and satisfies physical properties such as required strength and flexibility. As the support, for example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, triacetic acid, etc.) Cellulose, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), metal laminated or vapor deposited paper, plastic film Can be mentioned.

  As a support that can be applied to a lithographic printing plate precursor, 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.

  The composition of the aluminum plate applicable to the present invention is not specified, and an aluminum plate made of a publicly known material can be used as appropriate. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.12 mm to 0.4 mm.

  Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in Japanese Patent Laid-Open No. 54-63902, a method in which both are combined can also be used. Among these, it is preferable to include a step of roughening at least in a hydrochloric acid electrolyte.

The roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization treatment if desired in order to enhance the water retention and wear resistance of the surface. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte. The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm ^2. A voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable. When the amount of the anodized film is less than 1.0 g / m ² , the printing durability is insufficient, or the non-image portion of the planographic printing plate is easily damaged, and the ink adheres to the damaged portion during printing. So-called “scratch stains” easily occur.

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

The lithographic printing plate precursor according to the present invention is provided with a recording layer having a multi-layer structure including the upper layer and the lower layer as described above on the support, and if necessary, between the support and the lower layer, Further, an undercoat layer can be provided. By providing this undercoat layer, the undercoat layer between the support and the recording layer functions as a heat insulating layer, and the heat generated by the infrared laser exposure does not diffuse to the support and can be used efficiently. Therefore, there is an advantage that high sensitivity can be achieved. Various organic compounds are used as the primer layer component, such as carboxymethylcellulose, dextrin, gum arabic, phosphonic acids having amino groups, organic phosphonic acids, organic phosphoric acids such as phenylphosphoric acid, organic phosphinic acids, amino acids And a hydrochloride of an amine having a hydroxy group, and a polymer compound having a component having an acid group and a component having an onium group described in JP-A No. 2000-241962. The coverage of the undercoat layer is in terms of printing durability, 2 to 200 mg / m ² are suitable, and preferably from 5 to 100 mg / m ^2.

-Prepress processing of lithographic printing plate precursors-
〔exposure〕
The lithographic printing plate precursor according to the invention is image-formed by heat. Specifically, an image is formed by scanning exposure using a solid-state high-power infrared laser such as a semiconductor laser or a YAG laser that emits infrared light having a wavelength of 700 to 1200 nm. The planographic printing plate precursor of the present invention can also form an image by direct image-like recording using a thermal recording head or the like, high-illuminance flash exposure such as a xenon discharge lamp, or infrared lamp exposure.

The output of the infrared laser is preferably 100 mW or more, and a multi-beam laser device is preferably used in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec, and the energy irradiated to the recording material is preferably 10 to 500 mJ / cm ² .

〔developing〕
The exposed lithographic printing plate precursor is preferably developed with an alkaline aqueous solution having a pH of 12 or higher that does not substantially contain an organic solvent. Here, “substantially free of organic solvent” means that it does not contain an organic solvent to the extent that it causes inconvenience in terms of environmental health, safety, workability, etc. The ratio of the organic solvent in the developer is 0.5% by weight or less, preferably 0.3% by weight or less, and most preferably not contained at all. Moreover, although pH is 12.0 or more, More preferably, it is 12.0-14.0.

  A conventionally known alkaline aqueous solution can be used as the developer (hereinafter referred to as developer including the replenisher). For example, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples thereof include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium and lithium. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are listed. These alkaline aqueous solutions may be used individually by 1 type, and may use 2 or more types together.

  Among the above alkaline aqueous solutions, one of the developing solutions that exert the effect according to the present invention is a so-called one containing an alkali silicate as a base, or containing an alkali silicate by mixing a silicon compound with a base. An aqueous solution having a pH of 12 or more called “silicate developer”, and another more preferable developer does not contain an alkali silicate but contains a non-reducing sugar (an organic compound having a buffering action) and a base. Non-silicate developer ".

  Various surfactants and organic solvents can be added to the developer and replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, or improving ink affinity of the printing plate image area. . As the surfactant, anionic, cationic, nonionic and amphoteric surfactants are preferable. Further, the developer and replenisher may contain a reducing agent such as sodium salt and potassium salt of inorganic acids such as hydroquinone, resorcin, sulfurous acid, and bisulfite, as well as organic carboxylic acid, antifoaming agent, hard water, if necessary. Softeners and the like can be added.

  The lithographic printing plate precursor developed using a developer and a replenisher is post-treated with a desensitizing solution containing rinsing water containing a washing water, a surfactant and the like, gum arabic and starch derivatives. As post-processing, these processes can be used in various combinations.

  Further, when developing using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than that of the developer is added to the developer, so that a large amount of developer can be obtained without replacing the developer in the developer tank for a long time. It is known that PS plates can be processed. This replenishment method is also preferably applied in the present invention.

  The printing plate developed using the developer and the replenisher is post-treated with a desensitizing solution containing washing water, a rinsing solution containing a surfactant or the like, gum arabic or a starch derivative. As the post-treatment of the lithographic printing plate precursor using the photosensitive composition of the present invention, these treatments can be used in various combinations.

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

  The lithographic printing plate obtained as described above can be subjected to a printing process after applying a desensitized gum if desired. However, if it is desired to make a lithographic printing plate with a higher printing durability, if desired, Burning process is performed. In the case of burning a lithographic printing plate, before burning, an adjustment as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 is used. It is preferable to treat with a surface liquid.

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

  EXAMPLES Hereinafter, although this invention is demonstrated according to an Example, the scope of the present invention is not limited to these Examples.

[Example 1]
(Production of support)
The support body was produced by processing through the process shown below using a JIS-A-1050 aluminum plate with a thickness of 0.3 mm.

The above aluminum plate was sprayed with an aqueous NaOH solution (concentration 26 mass%, aluminum ion concentration 6.5 mass%) at a temperature of 70 ° C. to dissolve the aluminum plate 6 g / m ² . Thereafter, washing with water was performed using well water.
Next, it was desmutted by spraying with a 1% by weight aqueous solution of nitric acid having a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying.
Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 7.5 g / liter aqueous solution (containing 5 g / liter of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform was a rectangular wave, and an electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type. The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 450 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode.
Thereafter, washing with water was performed using well water.

The aluminum plate subjected to the above treatment is subjected to an etching process by spraying at a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% at 32 ° C., and the aluminum plate is dissolved at 0.10 g / m ^2. The smut component mainly composed of aluminum hydroxide generated during the electrochemical surface roughening treatment was removed, and the edge portion of the generated pit was melted to smooth the edge portion. Thereafter, washing with water was performed using well water.

Subsequently, desmutting treatment was performed by spraying with an aqueous solution having a sulfuric acid concentration of 25% by mass (containing 0.5% by mass of aluminum ions) at a temperature of 60 ° C., followed by washing with water using well water.
Next, an anodizing treatment was performed. The electrolytic solution had a sulfuric acid concentration of 170 g / liter (containing 0.5% by mass of aluminum ions) and a temperature of 43 ° C. Thereafter, washing with water was performed using well water. The current density was about 30A / dm ^2. The final oxide film amount was 2.7 g / m ² .

  Further, an anodized aluminum plate was immersed for 5 seconds in a solution obtained by heating a 0.5% polyvinylphosphonic acid aqueous solution to 60 ° C., and washed with water by spraying.

  As described above, a support used for the photosensitive lithographic printing plate precursor according to the example was obtained.

(Formation of the lower layer)
The lower layer coating liquid A having the following composition was applied to the support obtained above with a wire bar, and then dried for 50 seconds in a drying oven set at 140 ° C. to form a lower layer. The coating amount of the lower layer after drying was 1.2 g / m ² .

・エチルバイオレット ０．０５ｇ
・メチルエチルケトン ５．００ｇ
・１−メトキシ−２−プロパノール ５．００ｇ
・Ｎ，Ｎ−ジメチルホルムアミド １０．００ｇ <Coating liquid A for lower layer>
・ High molecular compound (1)
(The compound described above as an exemplary compound, a / b = 80/20 (molar ratio),
Weight average molecular weight 20,000) 0.80 g
・ Cyanine dye P (the following structure) 0.15g

・ Ethyl violet 0.05g
・ Methyl ethyl ketone 5.00g
・ 1-methoxy-2-propanol 5.00g
・ N, N-dimethylformamide 10.00g

(Formation of upper layer)
On the lower layer formed as described above, an upper layer coating solution A having the following composition was coated with a wire bar, and then dried for 60 seconds in a drying oven set at 130 ° C. to obtain an upper layer. The coating amount of the upper layer after drying was 0.4 g / m ² .

<Upper layer coating liquid A>
-Novolak resin (weight average molecular weight 5,000) of m-cresol / p-cresol / phenol = 45/30/25 (molar ratio) 0.95 g
・ Cyanine dye P (the above structure) 0.05 g
・ Methyl ethyl ketone 10.00g
1-methoxy-2-propanol 10.00g

  In this way, a lithographic printing plate precursor (A) of Example 1 was obtained.

[Examples 2 to 6]
In Example 1, instead of the polymer compound (1) used for forming the lower layer, the above-described polymer compounds (2) to (6) were used as exemplary compounds of the specific polymer compound, respectively. In the same manner as in Example 1, lithographic printing plate precursors (ii) to (ka) of Examples 2 to 6 were obtained.

  The details of the structures and molecular weights of the polymer compounds (2) to (6) used are as described above.

[Example 7]
In Example 1, the addition amount of the polymer compound (1) used for forming the lower layer was changed to 0.40 g, and as other polymer compounds, m-cresol / p-cresol = 60/40 novolak. 0.10 g of resin (weight average molecular weight 5,000), copolymer of N-phenylmaleimide / methacrylamide / acrylonitrile / N- (p-hydroxyphenyl) methacrylamide = 5/10/50/35 (molar ratio) A lithographic printing plate precursor (ki) of Example 7 was obtained in the same manner as in Example 1 except that 0.30 g (weight average molecular weight 70,000) was added.

[Example 8]
In Example 5, the addition amount of the polymer compound (5) used for forming the lower layer was changed to 0.60 g, and as other polymer compounds, m-cresol / p-cresol = 60/40 novolak resin ( A lithographic printing plate precursor (6) of Example 8 was obtained in the same manner as in Example 1 except that 0.20 g of a weight average molecular weight of 5,000) was added.

[Comparative Example 1]
In Example 1, instead of the polymer compound (1) used for forming the lower layer, a copolymer of N-phenylmaleimide / methacrylamide / methacrylic acid = 45/35/20 (molar ratio) (weight average molecular weight 50) , 000) was used in the same manner as in Example 1 to obtain a lithographic printing plate precursor (Ke) of Comparative Example 1.

[Comparative Example 2]
In Example 8, a lithographic printing plate precursor (ko) of Comparative Example 2 was obtained in the same manner as in Example 8 except that no upper layer was provided.

<Evaluation of planographic printing plate precursor>
1. Evaluation of chemical resistance Each of the obtained lithographic printing plate precursors (a) to (ko) was subjected to a dot set of 175 lpi / 2400 dpi on a Trendsetter 3244 manufactured by Creo under the conditions of a beam intensity of 10.0 W and a drum rotation speed of 250 rpm. Drawing (exposure) was performed on an image of a test pattern containing a chart with an area ratio of 1 to 99%.
Next, using a PS processor LP-940HII manufactured by Fuji Photo Film Co., Ltd., a lithographic printing plate was obtained by performing a developing process and a gumming process at a developer temperature of 30 ° C. and a developing time of 12 seconds. At this time, as a developer, a solution obtained by diluting a developer “DT-2” manufactured by Fuji Photo Film Co., Ltd. 1: 8 with water, and as a gum solution, “Fuji Photo Film Co., Ltd. A solution obtained by diluting “FG-1” 1: 1 with water was used.
Printing was performed using the lithographic printing plate thus obtained. At this time, Lislon printing machine made by Komori Corporation was used as the printing machine, “Barius G” ink made by Dainippon Ink and Chemicals was used as ink, and Fuji Photo Film was used as dampening water. A solution obtained by diluting “IF-102” manufactured by Co., Ltd. with water to a concentration of 4% was used. Further, every time 5000 sheets were printed, the plate surface was wiped with a multi-cleaner manufactured by Fuji Photo Film Co., Ltd. Printing durability was evaluated based on the number of printed sheets when printed on high-quality paper and visually recognized that the density of the solid image started to decrease. A larger value means better chemical resistance. The results are shown in Table 1.

2. Evaluation of scratch resistance The obtained lithographic printing plate precursors (A) to (KO) were rubbed 15 times with an Abrazer felt CS5 to which a load of 250 g was applied, using a rotary ablation tester manufactured by TOYOSEIKI.
Next, this plate was developed using the developer “DT-2” as a developer by the same method as the evaluation of chemical resistance described above.
For the plate thus obtained, the density of the plate surface was measured with a Macbeth densitometer on the part subjected to friction and the part not subjected to friction, and the absolute value of the difference was calculated. The results are shown in Table 1. The larger the value, the greater the damage to the plate due to friction.

As shown in Table 1, the lithographic printing plate precursors (A) to (K) of the examples have good chemical resistance, small value of concentration change before and after friction, and good scratch resistance. It was the original edition.
On the other hand, the lithographic printing plate precursor of the comparative example which does not contain the specific polymer compound in the lower layer was a lithographic printing plate precursor having poor chemical resistance, although there was no problem in scratch resistance. Further, the lithographic printing plate precursor (this) of Comparative Example 2 having no upper layer was a lithographic printing plate precursor inferior in both chemical resistance and scratch resistance.

  As shown in the above Examples, it can be seen that a lithographic printing plate precursor excellent in both chemical resistance and scratch resistance can be obtained by the present invention.

Claims (1)

A polymer compound having a phenolic hydroxyl group and having a group represented by the following general formula (1) or the following general formula (2) in the side chain, and an infrared absorber are contained on a support having a hydrophilic surface. A photosensitive lithographic printing plate precursor for infrared laser, comprising a lower layer and an upper layer containing a water-insoluble and alkali-soluble resin in this order.

In General Formula (1) or General Formula (2), R represents an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 15 carbon atoms, or an alkenyl group having 2 to 12 carbon atoms.