JP4709104B2 - Photosensitive lithographic printing plate precursor - Google Patents

Description

  The present invention relates to a photosensitive lithographic printing plate precursor, and more particularly to a photosensitive lithographic printing plate precursor capable of direct plate making by scanning with infrared laser light based on a digital signal from a computer or the like.

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.
An infrared laser lithographic printing plate precursor using an infrared laser having a light emitting region from the near infrared to the infrared region as an exposure light source includes a binder resin and an IR dye that absorbs light and generates heat as essential components. Things are common. When such a lithographic printing plate precursor for infrared laser is exposed with an infrared laser, in the case of a plate material having a positive recording layer, in the unexposed portion (image portion), the IR dye and the like in the recording layer are mixed with the binder resin. It acts as a dissolution inhibitor that substantially lowers the solubility of the binder resin by the above interaction. 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 or the like and the binder resin is weakened. Therefore, at the time of development, the exposed portion (non-image portion) is dissolved in an alkaline developer and removed to form a lithographic printing plate.

In such a lithographic printing plate precursor for infrared laser, improvement in chemical resistance and improvement in scratch resistance are given 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 it is insufficient from the viewpoint of compatibility with scratch resistance. In addition, it is considered that the resin layer structure of the lithographic printing plate precursor having two or more layers is useful for achieving both chemical resistance and scratch resistance. For example, a polymer compound having a maleimide compound as a constituent unit in the lower layer Has been proposed (see, for example, Patent Document 2), but the adhesion between the lower layer and the upper layer is not always sufficient, and further level-up has been desired.
US Published Patent No. 2004/0020484 US Published Patent No. 2004/0067432

  The object of the present invention, which has been made to overcome the above-mentioned drawbacks of the prior art, is a photosensitive lithographic printing plate precursor for infrared lasers which is excellent in chemical resistance and scratch resistance, and also in the printing durability of the resulting lithographic printing plate. Is to provide.

As a result of diligent research, the present inventor has found that the above-described object can be achieved 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 comprises, on a support having a hydrophilic surface, a lower layer containing a polymer compound having a phenolic hydroxyl group and an infrared absorber, (A) styrene, (B) An upper layer containing a polymer compound having at least a polymerizable monomer having an alkylene oxide group as a copolymerizable component is provided in this order.

  By forming the photosensitive lithographic printing plate precursor according to the present invention in the above-described configuration, the photosensitive lithographic printing plate precursor is excellent in printing durability of an image portion to be formed, and further excellent in both chemical resistance and scratch resistance. Can do.

The photosensitive lithographic printing plate precursor for infrared laser according to claim 2 of the present invention is characterized in that the polymer compound contained in the upper layer further has (C) (meth) acrylonitrile as a copolymerizable component. To do.

Thus, in addition to (A) and (B) as a copolymerizable component, a polymer compound further having (C) (meth) acrylonitrile is used as the copolymerizable component in the copolymer, thereby providing chemical resistance and scratch resistance. Can be improved.
Here, (meth) acrylonitrile refers to either or both of acrylonitrile and methacrylonitrile.

  Here, “provided in 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 provided as desired, for example, undercoat The existence of layers, protective layers, backcoat layers, etc. is not denied.

  Although the action of the present invention is not clear, the strength and chemical resistance of the coating formed by a polymer compound having at least styrene and a polymerizable monomer having an alkylene oxide group as a copolymerization component used in the upper layer are excellent. Therefore, it is presumed that the photosensitive lithographic printing plate precursor for infrared laser obtained by using this can be excellent in scratch resistance and chemical resistance. Furthermore, by containing a polymer compound having a phenolic hydroxyl group in the lower layer, an interaction occurs between the side chain of the polymer compound in the upper layer and the phenol group, thereby improving the adhesion between the upper layer and the lower layer. It is presumed that the printing durability of the photosensitive lithographic printing plate for infrared laser has been improved.

  According to the present invention, it is possible to provide a photosensitive lithographic printing plate precursor for infrared laser which is excellent in chemical resistance and scratch resistance, and further excellent in printing durability of the obtained lithographic printing plate.

[Photosensitive lithographic printing plate precursor for infrared laser]
The photosensitive lithographic printing plate precursor for infrared laser of the present invention (hereinafter also referred to as a lithographic printing plate precursor) contains a polymer compound having a phenolic hydroxyl group and an infrared absorber on a support having a hydrophilic surface. And a lower layer containing at least a polymer compound having at least (A) a styrene and (B) a polymerizable monomer having an alkylene oxide group as a copolymerizable component.
By adopting the above-described constitution in which different polymer compounds are contained in the upper layer and the lower layer, respectively, a photosensitive lithographic printing plate precursor for an infrared laser having both excellent chemical resistance and scratch resistance and excellent printing durability is obtained. Can be provided.
Hereinafter, each item of the lithographic printing plate precursor according to the invention will be described in order.

[Polymer compound having phenolic hydroxyl group used for lower layer]
As the polymer compound having a phenolic hydroxyl group, known novolak resins, xylenol resins, resol resins and the like can be used.
Specifically, 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 resin, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4 Examples thereof include xylenol, 3,5-xylenol resin, xylenol / phenol mixed resin, xylenol / novolak mixed resin, xylenol / novolak / phenol mixed resin, and polycondensation polymer of pyrogallol 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 ester or methacrylic ester having a phenol group, hydroxystyrene or the like is used as a copolymer component. High molecular compounds.

  Among these, a novolak resin is preferable, and among them, phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol mixed formaldehyde resin can be mentioned. .

The polymer compound having a phenolic hydroxyl group used in the present invention is preferably contained in the lower layer in a proportion of 10 to 99% by mass from the viewpoint of improving printing durability, and more preferably 20 to 95% by mass.
By containing the polymer compound having a phenolic hydroxyl group in a proportion of 10 to 99% by mass in the lower layer, it is preferable in terms of improving printing durability presumed to be caused by the interaction with the upper layer polymer compound. .

[High molecular compound used in the upper layer (vinyl copolymer)]
In the present invention, the polymer compound used for the upper layer (hereinafter also referred to as a specific vinyl copolymer) is a high compound having at least (A) styrene and (B) a polymerizable monomer having an alkylene oxide group as a copolymerizable component. It contains a molecular compound.
Further, (C) (meth) acrylonitrile is preferably used as a copolymerization component from the viewpoint of improving scratch resistance and chemical resistance.

  The alkylene in the polymerizable monomer (B) having an alkylene oxide group preferably has 2 to 10 carbon atoms, and more preferably 2 to 4 carbon atoms in terms of improving scratch resistance, chemical resistance, and developability.

  Furthermore, the compound represented by general formula (II) which is a polymerizable monomer having the following ethylene oxide group among the polymerizable monomers having the (B) alkylene oxide group is preferable.

In general formula (II), R ₃ represents a hydrogen atom or a methyl group. R ₄ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a phenyl group, preferably a hydrogen atom or a methyl group. N ₁ represents an integer of 1 to 100, preferably 1-30.
Examples of such vinyl monomers include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, polyethylene glycol methacrylate, and polyethylene glycol methyl ether methacrylate.

The component (B) of the specific vinyl copolymer may have two or more corresponding components as structural units.
The specific vinyl copolymer may be a copolymer having another structural unit other than the above-described structural units (A), (B), and (C). The copolymer component is not particularly specified as long as it is a monomer that can be copolymerized with these structural units, and examples thereof include various compounds having an acrylic group or a methacryl group.

  Examples of suitable vinyl copolymers that can be used in the present invention include (1) styrene / acrylonitrile / polyethylene glycol methacrylate, (2) styrene / acrylonitrile / polyethylene glycol methyl ether methacrylate, and (3) styrene / acrylonitrile / 2-hydroxy. Ethyl methacrylate / polyethylene glycol methyl ether methacrylate, (4) styrene / acrylonitrile / 2-hydroxyethyl methacrylate / [2- (methacryloyloxy) ethyl] trimethylammonium chloride, (5) styrene / polyethylene glycol methacrylate, (6) styrene / hydroxy Mention may be made of ethyl methacrylate / polyethylene glycol methacrylate.

The mol% of the constituent components in the specific vinyl copolymer is 10 to 95 mol% and (B) 5 to 90 mol% from the viewpoint of achieving both printing durability and developability. Preferably, (A) is 20 to 90 mol%, and (B) is more preferably 10 to 80 mol%.
By containing 10 to 95 mol% of (A) and 5 to 90 mol% of (B), both printing durability and developability can be achieved.

Further, when (C) is further included as a constituent component, (A) is preferably 10 to 95 mol%, (B) is preferably 5 to 90 mol%, and (C) is preferably 1 to 50 mol%, More preferably, A) is 20 to 90 mol%, (B) is 10 to 80 mol%, and (C) is 5 to 35 mol%.
The molar ratio (mol%) of the constituent components in the specific vinyl copolymer is (A) 10 to 95 mol%, (B) 5 to 90 mol%, and (C) 1 to 50 mol%. Thus, a vinyl copolymer having excellent chemical resistance and strength can be obtained, and the lithographic printing plate precursor prepared by using it can be excellent in chemical resistance and scratch resistance.

  Further, the weight average molecular weight of the specific vinyl copolymer is preferably 1,000 or more, and more preferably 1,000 to 500,000, from the viewpoint of strength and chemical resistance.

  The specific vinyl copolymer used in the present invention is preferably contained in the upper layer in a proportion of 10 to 99% by mass in terms of chemical resistance and strength, and when used alone, it is 50 to 99% by mass. Particularly preferred. Moreover, when the said specific vinyl type copolymer is included in the ratio of 10-50 mass% in an upper layer, it is preferable to use together other high molecular compounds other than the said specific vinyl type copolymer.

[Other polymer compounds]
In the lower layer and the upper layer in the present invention, in addition to the above-described polymer compound, another polymer compound can be used in combination, and the other polymer compound used in combination may be one type or two or more types. Moreover, when using another high molecular compound for the said lower layer and upper layer, it is preferable that it is another different high molecular compound, respectively.
Here, these polymer compounds are described.
The other polymer compound that can be used in the present invention is preferably a polymer compound that is soluble or swellable in an alkaline aqueous solution. Examples of such a polymer compound include polymer compounds having the acidic groups listed in the following (1) to (6) in the main chain and / or side chain of the polymer.
(1) Phenol group (-Ar-OH)
(2) Sulfonamide group (—SO ₂ NH—R)
(3) Substituted sulfonamide acid group (hereinafter referred to as “active imide group”)
[—SO ₂ NHCOR, —SO ₂ NHSO ₂ R, —CONHSO ₂ R]
(4) Carboxylic acid group (—CO ₂ H)
(5) Sulfonic acid group (—SO ₃ H)
(6) phosphoric acid group (-OPO ₃ H ₂₎
In the above (1) to (6), 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 other polymer compound having an acidic group selected from the above (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, 2,5-xylenol, 2,6-xylenol, 3, 4-xylenol, 3,5-xylenol resin, xylenol / phenol mixed resin, Shirenoru / novolac mixed resin, may be mentioned xylenol / novolak / phenol mixed resin, and the condensation polymer of pyrogallol 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 ester or methacrylic ester having a phenol group, hydroxystyrene or the like is used as a copolymer component. High molecular compounds.

  (2) Examples of the polymer compound having a sulfonamide group include a polymer composed of a minimum structural unit derived from a compound having a sulfonamide group as a main structural unit. Examples of the compound as described above include compounds having at least one sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom and one or more polymerizable unsaturated groups in the molecule. Among these, low molecular weight compounds having an acryloyl group, an allyl group, or a vinyloxy group, and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group in the molecule are preferable. For example, the following formulas (i) to (v ).

(In the formula, X ¹ and X ² each independently represent —O— or —NR ^7. R ¹ and R ⁴ each independently represents a hydrogen atom or —CH _3. R ² , R ⁵ , R ⁹ , R ¹² and R ¹⁶ each independently represents an alkylene group, a cycloalkylene group, an arylene group or an aralkylene group having 1 to 12 carbon atoms, and R ³ , R ⁷ and R ¹³ each independently represent Represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group, and R ⁶ and R ¹⁷ are each independently an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aryl group. 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 an alkylene having 1 to 12 carbon atoms. Group, cycloalkylene group, arylene group or aralkylene group Y ¹ and Y ² each independently represents a single bond or CO. The above alkylene group, cycloalkylene group, arylene group, aralkylene group, alkyl group, cycloalkyl The group, aryl group, or aralkyl group may have a substituent, and a preferred substituent is an alkyl group.)

  Among the compounds represented by formulas (i) to (v), in the multilayer sensitive material type printing plate precursor of the present invention, in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) acrylamide and the like can be preferably used.

  (3) As a high molecular compound which has an active imide group, the polymer which makes the minimum structural unit derived from the compound which has an active imide group the main structural unit can be mentioned, for example. Examples of the compound as described above include compounds each having one or more active imide groups represented by the following structural formula and polymerizable unsaturated groups in the molecule.

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

(4) As 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 polymerizable unsaturated group in the molecule is a main structural unit. 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 structural unit. 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) above, (1) a phenol group, (2) a sulfonamide group, (3) an active imide group, and (4) a carboxylic acid group Molecular compounds are 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.

Moreover, the minimum structural unit having an acidic group selected from the above (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. If it is less than 3 mol%, the solubility in an alkaline developer containing substantially no solvent will decrease.

As the monomer component to be copolymerized with the polymerizable monomer having an acidic group, for example, monomers listed in the following (m1) to (m11) can be used, 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-phenylmaleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

  In the present invention, other polymer compounds may be used in combination with two or more different polymer compounds.

  Among the other polymer compounds exemplified above, the other polymer compound that can be used in the lower layer is preferably a copolymer having a sulfonamide group and / or a carboxylic acid group, Can include alkyl (meth) acrylate, (meth) acrylamide, (meth) acrylonitrile, and N-phenylmaleimide.

  As other polymer compounds that can be used in the upper layer, novolac resins and xylenol resins are preferably used, such as phenol formaldehyde resins, m-cresol formaldehyde resins, p-cresol formaldehyde resins, m- / p-mixed cresols. Formaldehyde resin, phenol / cresol (m-, p-, o-, m- / p-mixed, m- / o-mixed and o- / p-mixed) mixed formaldehyde resin, 2,3-xylenol 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol resin, xylenol / phenol mixed resin, xylenol / novolak mixed resin, xylenol / novolak / phenol mixed Examples thereof include resins.

In the present invention, when the polymer compound having a phenolic hydroxyl group used in the lower layer is a cocondensation type resin using an aldehyde such as a phenol formaldehyde resin or a cresol aldehyde resin, the weight average molecular weight is 500 to 20,000. The number average molecular weight is preferably 200 to 10,000.
When the polymer compound having a phenolic hydroxyl group used in the lower layer is a polymer compound other than a cocondensation resin using an aldehyde such as phenol formaldehyde resin or cresol aldehyde resin, the weight average molecular weight is 2,000 or more, several Those having an average molecular weight of 500 or more are preferable, and 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 degree of dispersion (weight average molecular weight / number average molecular weight). Is 1.1-10.

  As the addition amount of the other polymer compound in the present invention, both the upper layer and the lower layer are used in an addition amount of 30 to 99% by mass, preferably 50 to 99% by mass, particularly preferably 65 to 99% by mass. It is preferable that the addition amount of the polymer compound is within the above range because the upper layer and the lower layer thermosensitive layer have high durability and high sensitivity.

[Infrared absorber]
The lithographic printing plate precursor according to the invention contains an infrared absorber in the lower layer for high recording sensitivity and uniformity / durability of the lower layer.
As the infrared absorber, known various pigments and dyes are preferably exemplified. Examples of the pigment include a commercially available pigment and color index (CI) manual, “Latest Pigment Handbook” (edited by the Japan Pigment Technical Association, published in 1977), “Latest Pigment Applied Technology” (published by CMC, published in 1986), “ Examples thereof include pigments described in "Printing Ink Technology", published by CMC Publishing, 1984).

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments Quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black and the like.

  The pigment may be used without being subjected to a surface treatment or may be used after being subjected to a surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (for example, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The surface treatment method is described in “Characteristics and Application of Metal Soap” (Sachibo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). .

The particle diameter of the pigment is preferably 0.01 to 10 μm, more preferably 0.05 to 1 μm, and particularly preferably 0.1 to 1 μm. When the particle size of the pigment is within the above range, the coating solution is stable and a uniform lower layer (photosensitive layer) can be obtained.
The particle diameter of the pigment can be measured using a known measurement method. In this specification, a plurality of particle diameters are measured by observation with an optical microscope, an electron microscope, and the like, and an average value thereof is taken. is there.

  As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. For the dispersion, a disperser such as an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, or a pressure kneader is used. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

  Examples of the dye include commercially available dyes and known dyes described in the literature (for example, “Dye Handbook” edited by the Society of Synthetic Organic Chemistry, published in 1970). For example, azo dyes, metal complex azo dyes, pyrazolone azo dyes. And dyes such as dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, and cyanine dyes.

  Among the pigments or dyes, pigments and dyes that absorb infrared light or near infrared light are particularly preferable because they are suitable for use in lasers that emit infrared light or near infrared light.

  Carbon black is preferably used as the pigment that absorbs the infrared light or near infrared light.

Examples of the dye that absorbs the infrared light or near infrared light include, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, and JP-A-60-78787. Cyanine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc. -112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc. Naphthoquinone dyes, squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent 434,875.
Further, as the dye, a near-infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and substituted arylbenzo (described in US Pat. No. 3,881,924) Thio) pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363 59-84248, 59-84249, 59-146063, 59-146061, pyranyl compounds described in JP-A-59-216146, cyanine dyes described in US Pat. The pentamethine thiopyrylium salt described in No. 283,475 and the pyrilylation disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 Things, Epolight III-178, EpolightIII-130, Epolight III-125, EpolightV-176A or the like is used particularly preferably.
Moreover, as said dye, as another especially preferable example, the near-infrared absorptive dye described as U.S. Pat. No. 4,756,993 as the formulas (I) and (II) can be mentioned.

The amount of the pigment or dye that is an infrared absorber is preferably 0.01 to 50% by mass, more preferably 0.1 to 10% by mass, based on the total solid content of the lower layer.
In the case of the said dye, 0.5-10 mass% is especially preferable, and in the case of a pigment, 3.1-10 mass% is especially preferable.
When the amount of the pigment or dye added is within the above range, high recording sensitivity can be obtained, and the lower layer (photosensitive layer) is highly uniform and durable.

  An infrared absorber may be contained in the upper layer for improving sensitivity. In that case, the infrared absorber content is preferably 0.01 to 50% by mass, more preferably 0.1 to 30% by mass, based on the total solid content of the upper layer.

[Other ingredients]
Various additives can be further added to the layer provided on the lithographic printing plate precursor according to the invention, if necessary.
For example, in order to adjust the solubility of the layer provided on the lithographic printing plate precursor, other onium salts, aromatic sulfone compounds, aromatic sulfonic acid ester compounds, polyfunctional amine compounds, and the like can be added to the alkaline water-soluble polymer. It is preferable to add a so-called dissolution inhibitor that improves the function of preventing dissolution of (alkali-soluble resin) in the developer. Among them, onium salts, o-quinonediazide compounds, sulfonic acid alkyl esters, and the like are thermally decomposable and decomposed. In such a state, it is preferable to use a substance that substantially lowers the solubility of the alkali-soluble resin in terms of controlling the dissolution inhibition of the image area in the developer.

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

  Among these onium salts, diazonium salts and quaternary ammonium salts are particularly preferable from the viewpoints of dissolution inhibition ability and thermal decomposability. In particular, the diazonium salt is preferably a diazonium salt represented by the general formula (I) described in JP-A-5-158230 or a diazonium salt represented by the general formula (1) described in JP-A-11-143064. The diazonium salt represented by the general formula (1) described in JP-A-11-143064 having a small absorption wavelength in the visible light region is most preferable. Moreover, as a quaternary ammonium salt, the quaternary ammonium salt shown by (1)-(10) in (Chemical Formula 1) and (Chemical Formula 2) of Unexamined-Japanese-Patent No. 2002-229186 is preferable.

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

Suitable quinonediazides include o-quinonediazide compounds. The o-quinonediazide compound that can be 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 helps the solubility of the sensitive material system by both the effect of losing the ability to suppress the dissolution of the binder due to thermal decomposition and the change of o-quinonediazide itself into an alkali-soluble substance.
Examples of the o-quinonediazide compound that can be used in the present invention include J.P. 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) -diazidosulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide- described in US Pat. Nos. 3,046,120 and 3,188,210 Esters of 5-sulfonic acid chloride and phenol-formaldehyde resin are also preferably used.

  Further, an ester of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and phenol formaldehyde resin or cresol-formaldehyde resin, naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and pyrogallol-acetone resin Similarly, the esters are also preferably used. Other useful o-quinonediazide compounds are reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802, JP-A-48-63803, JP-A-48-96575, JP-A-49-38701, JP-A-48-13354, Japanese Patent Publication Nos. 41-11222, 45-9610, 49-17474, U.S. Pat. Nos. 2,797,213, 3,454,400, 3,544,323, 3,573,917, 3,674,495, 3,785,825, British Patents 1,227,602, 1,251,345, 1,267, No. 005, No. 1,329,888, No. 1,330,932, German Patent No. 854,890, and the like.

The addition amount of the onium salt and / or o-quinonediazide compound which is a degradable dissolution inhibitor is preferably 1 to 10% by mass, more preferably based on the total solid content of each layer provided in the lithographic printing plate precursor Is in the range of 1 to 5% by weight, particularly preferably 1 to 2% by weight. These compounds can be used alone, but may be used as a mixture of several kinds.
The amount of additives other than the o-quinonediazide compound is preferably 0.1 to 5% by mass, more preferably 0.1 to 2% by mass, and particularly preferably 0.1 to 1.5% by mass. The additive and binder according to the present invention are preferably contained in the same layer.

  Further, a dissolution inhibitor having no decomposability may be used in combination, and preferred dissolution inhibitors include sulfonate esters, phosphate esters, and aromatic carboxylic acids described in detail in JP-A-10-268512. Esters, aromatic disulfones, carboxylic anhydrides, aromatic ketones, aromatic aldehydes, aromatic amines, aromatic ethers, etc., as well as lactone skeletons described in detail in JP-A-11-190903, N, N- Examples thereof include an acid color-forming dye having a diarylamide skeleton and a diarylmethylimino skeleton, which also serves as a colorant, and nonionic surfactants described in detail in JP-A No. 2000-105454.

  In the lithographic printing plate precursor according to the invention, cyclic acid anhydrides, phenols, and organic acids can be used in combination for the purpose of improving sensitivity. Further, a surfactant, an image colorant, and a plasticizer, which will be described later, can also be used in the lower layer functioning as a positive recording layer in the present invention, and further in the upper layer if desired.

  Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, 3,6-endooxy-4-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride described in US Pat. No. 4,115,128, Maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used.

  As phenols, bisphenol A, 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'-tetramethyltriphenylmethane and the like.

  Furthermore, examples of organic acids include sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942, JP-A-2-96755, and the like. Etc.

  The proportion of the cyclic acid anhydride, phenols, and organic acids in the upper layer or lower layer of the lithographic printing plate precursor is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, Especially preferably, it is 0.1-10 mass%.

  In addition to these, epoxy compounds, vinyl ethers, and further, phenol compounds having a hydroxymethyl group, phenol compounds having an alkoxymethyl group described in JP-A-8-276558, and the inventors previously proposed. A crosslinkable compound having an alkali dissolution inhibiting action described in JP-A-11-160860 can be appropriately added depending on the purpose.

Further, a printing-out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant can be added.
Typical examples of the printing-out agent include a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt.
Specifically, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A-50-36209 and JP-A-53-8128, 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 colorant for the image, 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) Manufactured by Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), and the like. The dyes described in JP-A-62-293247 are particularly preferred.
These dyes can be added to the upper layer or the lower layer 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 upper layer or the lower layer.

Furthermore, a plasticizer is added to the planographic printing plate precursor according to the present invention, if necessary, 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.

[Coating solvent and coating method]
The lithographic printing plate precursor of the present invention is prepared by preparing a coating solution in which components such as the polymer compound and infrared absorber contained in the lower layer and the upper layer described above are dissolved in a solvent, and forming a lower layer on a support having a hydrophilic surface. The lower layer and the upper layer can be manufactured and formed on the support by applying the coating liquid for coating and the coating liquid for upper layer in this order.
Further, depending on the purpose, a protective layer, a resin intermediate layer, a backcoat layer and the like, which will be described later, can be formed in the same manner.

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, toluene, and the like. It is not limited to. These solvents are used alone or in combination.
The concentration of the above components (total solid content including additives) in the coating solution is preferably 1 to 50% by mass.

The coating, solid coating amount on the support obtained after drying, the top layer 0.05 to 2.0 g / ^{m 2,} the lower layer is preferably each 0.3 to 5.0 g / ^{m 2,} more preferably The upper layer is in the range of 0.1 to 1.0 g / m ² , and the lower layer is in the range of 0.5 to 3.0 g / m ² . Moreover, 0.05-1 are preferable, and, as for ratio (upper layer / lower layer) 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 for applying the upper and lower layer coating solutions. For example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, roll Application etc. can be mentioned. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the photosensitive film deteriorate.

[Support]
As the support used in the lithographic printing plate precursor according to the invention, a support having a hydrophilic surface is used.

  The support is a dimensionally stable plate-like material and is not particularly limited as long as it satisfies physical properties such as necessary strength and flexibility. For example, paper, plastic (for example, polyethylene, polypropylene, Paper laminated with polystyrene, etc., metal plates (eg, aluminum, zinc, copper, etc.), plastic films (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.

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 mainly composed of aluminum containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited.
Examples of the different 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.

  As described above, 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 appropriately used. 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.

  The aluminum plate is roughened and used with a hydrophilic surface. Prior to the roughening, the surface of the aluminum plate is removed if desired. For example, a degreasing treatment with a surfactant, an organic solvent or an alkaline aqueous solution is performed. Done.

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 part of the lithographic printing plate precursor is easily scratched, and ink adheres to the scratched part during printing. The so-called “scratch stain” is likely to occur.

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

(Undercoat layer)
The lithographic printing plate precursor according to the invention has a lower layer as described above on a support, but an undercoat layer can be provided between the support and the lower layer as necessary.
By providing this undercoat layer, the undercoat layer between the support and the lower layer functions as a heat insulating layer, and heat generated by the exposure of the infrared laser does not diffuse to the support and is used efficiently. There is an advantage that sensitivity can be improved.
In addition, since the lower layer according to the present invention is located on the exposed surface or in the vicinity thereof even when the undercoat layer is provided, the sensitivity to the infrared laser is favorably maintained.
In the unexposed area, the lower layer itself, which is impermeable to the alkaline developer, functions as a protective layer for the undercoat layer, so that an image with excellent development stability and excellent discrimination is formed. In addition, it is considered that stability over time is also ensured.
In the exposed area, the lower layer component whose dissolution inhibiting ability is released is quickly dissolved and dispersed in the developer, and further, the undercoat layer itself adjacent to the support is made of an alkali-soluble polymer. Therefore, the solubility in the developer is good.For example, even when a developer with reduced activity is used, it dissolves quickly without the formation of a residual film, contributing to the improvement of the developability. This subbing layer is considered useful.

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

  Furthermore, an undercoat layer containing at least one compound selected from the group of organic polymer compounds having a structural unit represented by the following formula is also preferred.

In the formula, R ¹¹ represents a hydrogen atom, a halogen atom or an alkyl group, and R ¹² and R ¹³ each independently represent a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, -OR ^{14, -COOR} 15, represents a ^-CONHR 16, -COR ¹⁷ or -CN. R ¹² and R ¹³ may combine to form a ring. R ^{14 to} R ¹⁷ each independently represents an alkyl group or an aryl group, X represents a hydrogen atom, a metal atom, or NR ¹⁸ R ¹⁹ R ²⁰ R ²¹ , and R ^{18 to} R ²¹ each independently represents a hydrogen atom , An alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group, or R ¹⁸ and R ¹⁹ may be bonded to form a ring, and m represents an integer of 1 to 3.

Moreover, as a suitable undercoat layer component in the present invention, there can be mentioned a polymer compound having a structural unit having an acid group and a structural unit having an onium group, as described in JP-A No. 2000-241962.
Specific examples include a copolymer of a monomer having an acid group and a monomer having an onium group.
The acid group is preferably an acid group having an acid dissociation index (pKa) of 7 or more, more preferably —COOH, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , — CONHSO ₂ — or —SO ₂ NHSO ₂ —, particularly preferably —COOH.
Specific examples of the monomer having an acid group include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, itaconic acid, maleic acid, maleic anhydride, and styrene having the acid group.
Preferred as the onium group is an onium group composed of Group V or Group VI atoms, more preferably an onium group composed of nitrogen, phosphorus or sulfur atoms, and particularly preferably an onium group composed of nitrogen atoms. It is a group. Specific examples of the monomer having an onium group include styrene having a substituent containing an onium group such as a methacrylate having an ammonium group in the side chain, a methacrylamide, a substituent containing an onium group such as a quaternary ammonium group, and the like. It is done.
Furthermore, compounds described in JP-A No. 2000-108538, Japanese Patent Application No. 2002-257484, Japanese Patent Application No. 2003-78699, and the like can be used as necessary.

  These undercoat layers can be provided by the following method. That is, a method in which water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof is dissolved and applied on an aluminum plate and dried, and water, methanol, ethanol, methyl ethyl ketone, etc. In this method, an aluminum plate is immersed in a solution in which the above organic compound is dissolved in the above organic solvent or a mixed solvent thereof to adsorb the above compound, and then washed and dried with water or the like to provide an 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.
In addition, a yellow dye can be added to the undercoat layer in order to improve the tone reproducibility of the image recording material.

The coating amount of the undercoat layer, 2 to 200 mg / ^{m 2} are suitable, and preferably from 5 to 100 mg / ^{m 2.} If the coating amount is less than 2 mg / m ² , sufficient printing durability cannot be obtained. The same applies greater than 200 mg / ^{m 2.}

〔exposure〕
The planographic printing plate precursor of the present invention is image-formed by heat. Specifically, an image is formed by exposure with 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.
Direct image-like recording by a thermal recording head or the like, high-illuminance flash exposure such as a xenon discharge lamp, or infrared lamp exposure can also be used.
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 applied to the lithographic printing plate precursor is preferably 10 to 500 mJ / cm ² .

〔developing〕
In the present invention, the 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 of causing 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. Another more preferable developer, which is an aqueous solution called “silicate developer” having a pH of 12 or more, does not contain an alkali silicate, and contains a non-reducing sugar (an organic compound having a buffering action) and a base. Silicate developer ".

In the silicate developer, the aqueous solution of alkali metal silicate is a ratio of silicon oxide SiO ₂ and alkali metal oxide M ₂ O (generally [SiO ₂ ] / [M ₂ O], which is a component of silicate). The developability can be adjusted by adjusting the density and the density. For example, as disclosed in JP-A-54-62004, the molar ratio of SiO ₂ / Na ₂ O is 1.0 to 1. 5 (ie, [SiO ₂ ] / [Na ₂ O] is 1.0 to 1.5), and an aqueous solution of sodium silicate having a SiO ₂ content of 1 to 4% by mass, or Japanese Patent Publication No. 57-7427. [SiO ₂ ] / [M] is 0.5 to 0.75 (that is, [SiO ₂ ] / [M ₂ O] is 1.0 to 1.5) , the concentration of SiO ₂ is from 1 to 4 wt%, and the developing solution is present therein That total alkali metal based on the gram atoms containing potassium at least 20%, aqueous solution of an alkali metal silicate is preferably used.

In the case of a so-called “non-silicate developer” that does not contain an alkali silicate and contains a non-reducing sugar and a base, it is preferable to contain a non-reducing sugar having a buffering property that suppresses fluctuations in pH.
Non-reducing sugars are saccharides that do not have a free aldehyde group or ketone group and do not exhibit reducibility, trehalose-type oligosaccharides in which reducing groups are bonded, and glycosides in which reducing groups of saccharides are combined with non-saccharides. , And sugar alcohols reduced by hydrogenation of sugars, any of which can be used in the present invention. In the present invention, non-reducing sugars described in JP-A-8-305039 can be preferably used.

Examples of the trehalose type oligosaccharides include saccharose and trehalose. Examples of the glycoside include alkyl glycosides, phenol glycosides, and mustard oil glycosides. Examples of the sugar alcohol include D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit, D, L-talit, zulsiit, allozulcit and the like. . Further, maltitol hydrogenated to disaccharide maltose, reduced form obtained by hydrogenation of oligosaccharide (reduced water candy), and the like are preferable. Among these non-reducing sugars, trehalose-type oligosaccharides and sugar alcohols are preferable, and among them, D-sorbitol, saccharose, reduced syrup, etc. are preferable in that they have a buffering action in an appropriate pH region and are inexpensive.
These non-reducing sugars may be used alone or in combination of two or more.
The content of the non-reducing sugar in the non-silicate developer is preferably 0.1 to 30% by mass, and more preferably 1 to 20% by mass. When the content is in the range of 0.1 to 30% by mass, an appropriate buffer action is obtained, and it is preferable in terms of high concentration and cost reduction.

Examples of the base used in combination with the non-reducing sugar include conventionally known alkali agents such as inorganic alkali agents and organic alkali agents. Examples of the inorganic alkaline agent include sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, tripotassium phosphate, triammonium phosphate, disodium phosphate, dipotassium phosphate, diammonium phosphate, Examples thereof include sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium borate, potassium borate, and ammonium borate.
Examples of the organic alkali agent include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanol. Examples include amine, diisopropanolamine, ethyleneimine, ethylenediamine, and pyridine.
The said base may be used individually by 1 type, and may use 2 or more types together. Among these bases, sodium hydroxide and potassium hydroxide are preferable. In the present invention, as the non-silicate developer, a non-reducing sugar alkali metal salt as a main component can be used instead of the non-reducing sugar and the base.

In addition, an alkaline buffer composed of a weak acid other than the non-reducing sugar and a strong base can be used in combination with the non-silicate developer. The weak acid preferably has a dissociation constant (pKa) of 10.0 to 13.2, and can be selected from, for example, those described in Ionization Constants of Organic Acids Solution issued by Pergmon Press.
Specifically, alcohols such as 2,2,3,3-tetrafluoropropanol-1, trifluoroethanol, and trichloroethanol, pyridine-2-aldehyde (, aldehydes such as pyridine-4-aldehyde (such as salicylic acid, 3-hydroxy-2-naphthoic acid, catechol, gallic acid, sulfosalicylic acid, 3,4-dihydroxysulfonic acid, 3,4-dihydroxybenzoic acid, hydroquinone (11.56), pyrogallol, o-, m-, p -Compounds having a phenolic hydroxyl group such as cresol, resorsonol, oximes such as acetoxime, 2-hydroxybenzaldehyde oxime, dimethylglyoxime, ethanediamide dioxime, acetophenone oxime, adenosine, inosine, guanine, cytosine, hypoxanthine, chitosan Nucleic acid-related substances such as Nchin, other, diethylaminomethyl acid, benzimidazole, and the like barbituric acid is preferably exemplified.

  Various surfactants and organic solvents can be added to the developer as necessary for the purpose of promoting or 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. Furthermore, in the developer, if necessary, a reducing agent such as sodium salt or potassium salt of inorganic acid such as hydroquinone, resorcin, sulfurous acid, or bisulfite, and further organic carboxylic acid, antifoaming agent, water softener, etc. Can be added.

The lithographic printing plate precursor developed using the developer is post-treated with a desensitizing solution containing washing water, a rinse solution containing a surfactant or the like, gum arabic or a starch derivative. As the post-treatment when the image forming material is used as a printing plate, these treatments can be used in various combinations.
Further, when developing using an automatic developing machine, the developer in the developing tank is replaced for a long time by using a developer obtained by adding an aqueous solution (replenisher) having a higher alkali strength than the developer to the developer. It is known that a large amount of PS plate can be processed without any problems. This replenishment method is also preferably applied in the present invention.
The printing plate developed with the developer is post-treated with a desensitizing solution containing washing water, a rinsing solution containing a surfactant and the like, gum arabic and starch derivatives. As the post-treatment of the lithographic printing plate precursor according to the 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.

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

The lithographic printing plate precursor obtained as described above can be subjected to a printing process after applying a desensitized gum if desired, but if it is desired to make a lithographic printing plate precursor with a higher printing durability, A burning process is performed if desired.
When burning a lithographic printing plate precursor, it is described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 before burning. It is preferable to treat with a surface conditioning liquid.
As a method thereof, a method of applying the lithographic printing plate precursor with a sponge or absorbent cotton soaked with the surface-adjusting liquid, or immersing and applying the printing plate in a vat filled with the surface-adjusting liquid, Application by an automatic coater is applied. Further, it is more preferable to make the coating amount uniform with a squeegee or a squeegee roller after coating.
In general, the amount of surface-adjusting solution applied is suitably 0.03 to 0.8 g / m ² (dry mass). The lithographic printing plate precursor coated with the surface-adjusting solution is dried if necessary, and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). Is done. In this case, the heating temperature and time are in the range of 180 to 300 ° C. and preferably in the range of 1 to 20 minutes, although depending on the type of components forming the image.

  The lithographic printing plate precursor that has been burned can be subjected to conventional treatments such as washing and gumming as needed, but a surface-conditioning solution containing a water-soluble polymer compound is used. In such a case, so-called desensitizing treatment such as gumming can be omitted. The lithographic printing plate precursor obtained by such treatment 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]
-Infrared laser photosensitive lithographic printing plate-
<Synthesis Example 1: Synthesis of Specific Vinyl Copolymer (1)>
In a 500 cc three-necked flask, 80 g of acetone and 80 g of toluene were mixed and lightly mixed, and then 9.4 g of styrene, 1.6 g of acrylonitrile, 28.8 g of polyethylene glycol methacrylate (the average number of polyethylene glycol repeating units was 20). ), And 0.3 g of 2,2′-azobisisobutyronitrile were added, heated to 60 ° C. with stirring under nitrogen reflux, and reacted for 6 hours. As it was, 0.3 g of 2,2′-azobisisobutyronitrile was additionally added, and the mixture was further reacted at 60 ° C. for 6 hours. Thereafter, the mixture was cooled to room temperature to obtain the desired copolymer. The weight average molecular weight was 30,000. This copolymer was used for preparing a photosensitive lithographic printing plate in the form of a solution.

(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., and the aluminum plate was dissolved at 6 g / m ² . Then, water washing by spraying was performed.
Next, a desmut treatment was performed by spraying with an aqueous solution of nitric acid having a concentration of 1% by mass (containing 0.5% by mass of aluminum ions) at a temperature of 30 ° C., and then washed with water using well water.
An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid concentration of 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 current peak value, and the amount of electricity was 450 C / dm ^{2 as} the total amount of electricity when the aluminum plate was the anode.
Thereafter, washing with water was performed using well water.

The aluminum plate obtained above was etched by spraying at 32 ° C. with a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass%, the aluminum plate was dissolved at 0.10 g / m ^2, and the previous stage AC was used. Thus, 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.
Subsequently, 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. Both current densities were about 30 A / 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. Thus, a support A for a photosensitive lithographic printing plate was obtained.

(Preparation of lithographic printing plate precursor)
On the hydrophilic surface of the support obtained above, a lower layer coating solution A having the following composition was coated with a wire bar, and then dried in a drying oven set at 140 ° C. for 50 seconds to form a lower layer. The coating amount after drying was 1.2 g / m ² .

<Coating liquid A for lower layer>
-Novolak resin 1 with m-cresol / p-cresol = 60/40 (molar ratio)
(Weight average molecular weight 8,000) 0.80g
・ Cyanine dye P (the following structure) 0.15g
・ Ethyl violet 0.05g
F-780-F (Dainippon Ink & Chemicals, Inc. fluorine-based surfactant) 0.05 g
・ Methyl ethyl ketone 5.00g
・ 1-methoxy-2-propanol 5.00g
・ Γ-Butyrolactone 10.00g

<Upper layer coating solution B>
-Specific vinyl copolymer (1) obtained in Synthesis Example 1 (styrene / acrylonitrile / polyethylene glycol methacrylate = 60/20/20 (molar ratio)), polyethylene glycol repeating units average 20 and weight average molecular weight 30,000 ) Solution 2.00g
・ Cyanine dye P (the above structure) 0.05 g
F-780-F (Dainippon Ink & Chemicals, Inc. fluorine-based surfactant) 0.05 g
・ Methyl ethyl ketone 10.00g
1-methoxy-2-propanol 10.00g

On the lower layer obtained as described above, an upper layer coating solution B having the following composition was coated with a curtain coater, and then dried in a drying oven set at 130 ° C. for 60 seconds to form an upper layer. A lithographic printing plate precursor 1 was obtained. The coating amount after drying was 0.4 g / m ² .

[Example 2]
Example 1 except that in the upper layer coating solution B of Example 1, the specific vinyl copolymer (2) synthesized in the same manner as in Synthesis Example 1 was used instead of the specific vinyl copolymer (1). In the same manner as described above, a photosensitive lithographic printing plate precursor 2 was obtained.
The specific vinyl copolymer (2) was synthesized by the same method as the method for synthesizing the specific vinyl copolymer (1) of Example 1. This specific vinyl copolymer (2) had a styrene / acrylonitrile / polyethylene glycol methyl ether methacrylate = 60/30/10 (molar ratio) and a weight average molecular weight of 10,000. The average number of polyethylene glycol repeating units was 12.

[Example 3]
Example 1 except that in the upper layer coating solution B of Example 1, the specific vinyl copolymer (5) synthesized in the same manner as in Synthesis Example 1 was used instead of the specific vinyl copolymer (1). In the same manner as above, a photosensitive lithographic printing plate precursor 3 was obtained.
The specific vinyl copolymer (5) was synthesized by the same method as the method for synthesizing the specific vinyl copolymer (1) of Example 1. The specific vinyl copolymer (5) had a styrene / polyethylene glycol methacrylate = 80/20 (molar ratio) and a weight average molecular weight of 20,000. The average number of polyethylene glycol repeating units was 12.

[Example 4]
Example 1 except that in the upper layer coating solution B of Example 1, the specific vinyl copolymer (3) synthesized in the same manner as in Synthesis Example 1 was used instead of the specific vinyl copolymer (1). In the same manner as above, a photosensitive lithographic printing plate precursor 4 was obtained.
This specific vinyl copolymer (3) was charged with styrene / acrylonitrile / 2-hydroxyethyl methacrylate / polyethylene glycol methyl ether methacrylate = 40/40/10/10 (molar ratio), and the resulting vinyl copolymer was obtained. The weight average molecular weight of (3) was 20,000. The average number of polyethylene glycol repeating units was 12.

[Example 5]
Example 1 except that the specific vinyl copolymer (4) synthesized in the same manner as in Synthesis Example 1 was used in place of the specific vinyl copolymer (1) in the upper layer coating solution B of Example 1. In the same manner as described above, a photosensitive lithographic printing plate precursor 5 was obtained.
This specific vinyl copolymer (4) was prepared by charging with styrene / acrylonitrile / 2-hydroxyethyl methacrylate / [2- (methacryloyloxy) ethyl] trimethylammonium chloride = 20/60/15/5 (molar ratio). The specific vinyl copolymer (4) thus obtained had a weight average molecular weight of 50,000.

[Example 6]
In the upper layer coating solution B of Example 1, the amount of the specific vinyl copolymer (1) is 1.50 g, and further a novolak resin of phenol / m-cresol / p-cresol = 50/30/20 (molar ratio). A photosensitive lithographic printing plate precursor 6 was obtained in the same manner as in Example 1 except that 0.2 g of 2 (weight average molecular weight 6,000) was used.

[Example 7]
In the lower layer coating solution A of Example 1, the amount of the novolak resin 1 was 0.40 g, and 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 except that 0.40 g was used to obtain a photosensitive lithographic printing plate precursor 7.

[Example 8]
In the lower layer coating solution A of Example 1, the amount of the novolak resin 1 was 0.30 g, and a copolymer of N-phenylmaleimide / methacrylamide / methacrylic acid = 45/35/20 (molar ratio) (weight average molecular weight) 50,000) 0.20 g, N- (p-aminosulfonylphenyl) methacrylamide / methyl methacrylate / acrylamide = 35/35/30 (molar ratio) copolymer (weight average molecular weight 80,000) 0 A photosensitive lithographic printing plate precursor 8 was obtained in the same manner as in Example 1 except that 30 g was used.

[Comparative Example 1]
In the upper layer coating solution B of Example 1, the same procedure as in Example 1 except that the novolak resin 2 described in Example 6 was used as the polymer compound instead of the specific vinyl copolymer (1). A printing plate precursor 9 was obtained.

[Comparative Example 2]
In the lower layer coating liquid A of Example 1, instead of the novolak resin 1, a copolymer (weight average molecular weight 50,000) of N-phenylmaleimide / methacrylamide / methacrylic acid = 45/35/20 (molar ratio) was used. A photosensitive lithographic printing plate precursor 10 was obtained in the same manner as in Example 1 except that it was used.

[Comparative Example 3]
In the lower layer coating liquid A of Example 1, instead of the novolak resin 1, a copolymer (weight average molecular weight 50,000) of N-phenylmaleimide / methacrylamide / methacrylic acid = 45/35/20 (molar ratio) was used. In the same manner as in Example 1 except that the novolak resin 2 described in Example 6 was used as the polymer compound instead of the specific vinyl copolymer (1) in the upper layer coating solution B. A plate original 11 was obtained.

[Evaluation of photosensitive lithographic printing plate precursor]
[Evaluation of printing durability and chemical resistance]
The photosensitive lithographic printing plate precursors 1 to 11 obtained above were subjected to a Trendsetter 3244 manufactured by Creo Corporation under conditions of a beam intensity of 10.0 W and a drum rotation speed of 250 rpm, and a dot area ratio of 175 lpi / 2400 dpi of 1 to 99%. Drawing (exposure) was performed on an image of a test pattern containing a chart.
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 (pH = 13.2, organic solvent content 0%, hereinafter referred to as “Developer 1”) As a gum solution, a solution obtained by diluting FG-1 manufactured by Fuji Photo Film Co., Ltd. with water to 1: 1 was used.

  Printing was performed using the lithographic printing plate thus obtained. At this time, Lilithon printing machine manufactured by Komori Corporation was used as the printing machine, Varius G ink ink manufactured by Dainippon Ink & Chemicals, Inc. as the ink, and Fuji Photo Film Co., Ltd. as the dampening water. Using IF-102 made by diluting IF-102 made with water to a concentration of 4%, and each time 5000 sheets were printed, part of the image was wiped with a multi-cleaner made by Fuji Photo Film Co., Ltd. It was. Depending on the number of copies printed when printing on high-quality paper and the solid image density began to fade, the printing durability (the part where the plate surface was not wiped with a cleaner) and chemical resistance (the plate surface was wiped with a cleaner) Were evaluated. Larger values mean better printing durability and chemical resistance. The results are shown in Table 1.

[Evaluation of scratch resistance]
The obtained photosensitive lithographic printing plate precursors 1 to 11 were rubbed 15 times with Abrazer felt CS5 to which a load of 250 g weight was applied using a rotary ablation tester manufactured by TOYOSEIKI.
Next, this plate was developed by the same method as the above-described evaluation of chemical resistance and printing durability, except that the above-described developer 1 was used as a developer.
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, in the photosensitive lithographic printing plate precursors of Examples 1 to 8, the printing durability and chemical resistance are large, and the scratch resistance is small, so all the characteristics are good. It is shown that. On the other hand, in the photosensitive lithographic printing plate precursors of Comparative Examples 9 to 11, the printing durability and chemical resistance are small, and the scratch resistance is large, indicating that both properties are inferior.
As shown in the above examples, a photosensitive lithographic printing plate precursor having excellent printing durability, chemical resistance and scratch resistance can be obtained.

Claims (2)

  On a support having a hydrophilic surface, a lower layer containing a polymer compound having a phenolic hydroxyl group and an infrared absorber, and (A) a styrene and (B) a polymerizable monomer having an alkylene oxide group are copolymerizable. A photosensitive lithographic printing plate precursor for infrared laser, comprising an upper layer containing at least a polymer compound as a component in this order. The photosensitive lithographic printing plate precursor for infrared laser according to claim 1, wherein the polymer compound contained in the upper layer further has (C) (meth) acrylonitrile as a copolymerizable component.