JP2008076516A - Lithographic printing plate precursor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive lithographic printing plate precursor for an infrared laser having excellent film forming property and film strength, high sensitivity, excellent developability and printing durability. <P>SOLUTION: The photosensitive lithographic printing plate precursor for an infrared laser has a recording layer containing a high molecular compound having a phenolic hydroxyl group, an infrared absorbent, a quaternary salt compound of a nitrogen-containing heterocycle and a vinyl copolymer having a polymerizable monomer having styrene and an ethylene oxide group as a constituent unit on a surface of a support having hydrophilicity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In recent years, the development of lasers has been remarkable. In particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can be easily obtained with high output and small size. These lasers are very useful as an exposure light source when directly making a plate from digital data such as a computer.

  The positive type lithographic printing plate material for infrared laser has an alkaline aqueous solution-soluble binder resin and an IR dye that absorbs light and generates heat as an essential component. In the unexposed part (image part), Acts as a dissolution inhibitor that substantially lowers the solubility of the binder resin through interaction with the binder resin. In the exposed area (non-image area), the interaction between the IR dye and the binder resin is weakened by the generated heat, resulting in an alkali. A lithographic printing plate is formed by dissolving in a developer.

As the alkaline aqueous solution-soluble binder resin in the positive planographic printing plate material, a polymer compound having a phenolic hydroxyl group such as a novolak resin is preferably used. However, the recording layer of a positive lithographic printing plate precursor using a novolak resin or the like may be insufficient in terms of film forming properties and film strength, and an improvement has been desired.
For the purpose of improving the film strength, an example in which polyacrylic acid is further used in combination with a positive photosensitive composition containing a photothermal conversion substance and an alkali-soluble resin is shown (for example, see Patent Document 1). Considering further enhancement of the sensitivity of the photosensitive layer, further improvement of the film strength is desired.

Moreover, an example in which methyl methacrylate- (meth) acrylic acid copolymer is further used in combination with a positive photosensitive composition containing a photothermal conversion substance and a novolak resin is also shown (for example, see Patent Document 2). However, it is still inadequate in terms of improving film strength while maintaining sensitivity.
Furthermore, polyvinyl acetal based on polyvinyl alcohol is known to have excellent mechanical properties and film forming properties, very good wear resistance, and good chemical resistance. Thus, an example of a photosensitive recording material using such polyvinyl acetal is shown (for example, see Patent Document 3). However, the sensitivity is low and the developability is insufficient, and improvement has been desired.
JP-A-10-282463 JP 2001-324808 A Special table 2003-530581 gazette

  Accordingly, an object of the present invention is to provide a photosensitive lithographic printing plate precursor for infrared laser having excellent film forming properties and film strength, high sensitivity, and excellent developability and printing durability.

As a result of extensive research, the present inventor has developed a photosensitive lithographic plate for infrared lasers, which includes a compound satisfying a certain condition and further includes a recording layer containing a vinyl copolymer comprising a specific constituent component. It has been found that the above problems can be solved by using a printing plate precursor, and the present invention has been completed.
That is, the present invention includes a polymer compound having a phenolic hydroxyl group, an infrared absorber, a nitrogen-containing heterocyclic quaternary salt compound, and a polymerizable monomer having a styrene and ethylene oxide group on the surface of a hydrophilic support. A photosensitive lithographic printing plate precursor for infrared laser, comprising a recording layer containing a vinyl copolymer having as a structural unit.
When a vinyl copolymer having styrene and a polymerizable monomer having an ethylene oxide group as a structural unit is formed, the ethylene oxide group is located in the side chain of the vinyl copolymer.

  Although the operation of the present invention is not clear, it is estimated as follows. That is, in the present invention, by using a vinyl copolymer in the recording layer, excellent film forming properties and film strength can be obtained by the polymer compound, and further, a polymer compound having a phenolic hydroxyl group and a nitrogen-containing compound can be obtained. By using a quaternary salt compound in combination, the vinyl copolymer and these components interact with each other to achieve further improvement in film strength in the unexposed areas, resulting in excellent printing durability. It is thought that sex is obtained. In the exposed area, when these interactions are quickly released, excellent developability can be obtained due to the ethylene oxide group contained in the nitrogen-containing quaternary salt compound or vinyl copolymer. thinking.

  According to the present invention, there can be provided a photosensitive lithographic printing plate precursor for infrared laser which has excellent film forming properties and film strength, can form an image with high sensitivity, and is excellent in developability and printing durability.

The photosensitive lithographic printing plate precursor for infrared laser of the present invention comprises a polymer compound having a phenolic hydroxyl group, an infrared absorbent, a nitrogen-containing heterocyclic quaternary salt compound, and styrene on the surface of a hydrophilic support. A photosensitive lithographic printing plate precursor for infrared laser, comprising a recording layer containing a vinyl copolymer having a polymerizable monomer having an ethylene oxide group as a constituent unit.
Below, each item is demonstrated one by one.

[Vinyl copolymer]
The vinyl copolymer used for the recording layer in the present invention is a polymer having styrene and a polymerizable monomer having an ethylene oxide group as structural units.
Here, the polymerizable monomer having an ethylene oxide group is represented by the following general formula (I).

In general formula (I), 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 1000.
The alkyl group and the phenyl group may further have a substituent, and examples of the substituent that can be introduced include a halogen, an alkyl group, a hydroxy group, and a hydroxyalkyl group.

  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 content of the styrene monomer and the monomer having an ethylene oxide group in the vinyl copolymer is preferably 10 to 95% by mass for the styrene monomer and 5 to 75% by mass for the polymerizable monomer having the ethylene oxide group. More preferably, the styrene monomer is 20 to 90% by mass, and the polymerizable monomer having an ethylene oxide group is 10 to 60% by mass.

  It is preferable that the vinyl copolymer further has another structural unit. The copolymer component is not particularly limited as long as it is a monomer that can be copolymerized with these structural units, and various compounds having an acrylic group or a methacryl group can be exemplified. Of these, acrylonitrile and methacrylonitrile are preferably used.

The weight average molecular weight of the vinyl copolymer is preferably 1,000 or more, more preferably 1,000 to 500,000.
The content of the vinyl copolymer is preferably 5 to 70% by mass, more preferably 10 to 50% by mass with respect to the total amount of the recording layer.

  Examples of vinyl copolymers that can be used in the present invention include (1) styrene / acrylonitrile / 2-hydroxyethyl methacrylate, (2) styrene / acrylonitrile / 2-methoxyethyl methacrylate, and (3) styrene / acrylonitrile / polyethylene glycol. Examples include methacrylate, (4) styrene / acrylonitrile / polyethylene glycol methyl ether methacrylate, (5) styrene / acrylonitrile / 2-hydroxyethyl methacrylate / polyethylene glycol methacrylate, and (6) styrene / polyethylene glycol methacrylate.

Among these, the synthesis example of (3) styrene / acrylonitrile / polyethylene glycol methacrylate is shown below.
(Synthesis Example 1)
In a 500 cc three-necked flask, add 80 g of acetone and 80 g of toluene, and mix lightly. 18 g of styrene, 20 g of acrylonitrile, 2 g of polyethylene glycol methacrylate (average repeat unit of ethylene glycol chain is 50), and 0. 25 g of 2,2′-azobisisobutyronitrile was added, and the mixture was 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 60,000. This copolymer was used for preparing a photosensitive lithographic printing plate precursor in the form of a solution.
Other copolymers (1) to (6) described above can also be synthesized by a method according to Synthesis Example 1.

[Polymer compound having phenolic hydroxyl group]
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.
These polymer compounds having a phenolic hydroxyl group may be used alone or in admixture of two or more.

  Of these, preferred are novolak resins, and among them, phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, and phenol / cresol mixed formaldehyde resin are preferable.

The novolak resin has a weight average molecular weight of 500 to 20,000, more preferably 1,000 to 15,000.
The content of the novolak resin is preferably 20 to 95% by mass and more preferably 30 to 90% by mass with respect to the total amount of the recording layer.

[Quaternary salt compound of nitrogen-containing heterocycle]
The nitrogen-containing heterocyclic quaternary salt compound used in the present invention is composed of a combination of a nitrogen-containing heterocyclic quaternary cation and an organic or inorganic anion.
Examples of the organic cation include an imidazolium cation, a pyridinium cation, and a pyrrolidinium cation, and preferably an imidazolium cation and a pyridinium cation.
Examples of the anion include methyl sulfonate, trifluoromethyl sulfonate, bromide, chloride, nitrate, tetrafluoroborate, hexafluorophosphate, and methyl sulfate, preferably tetrafluoroborate. . This is because tetrafluoroborate tends to lower the melting point.

  Examples of such onium salts include 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium nitrate, 1-ethyl-3-methylimidazole. Rium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium trifluoromethylsulfonate, 1-ethyl-2,3-dimethylimidazolium bromide, 1-ethyl-2 , 3-Dimethylimidazolium chloride, 1-ethyl-2,3-dimethylimidazolium nitrate, 1-ethyl-2,3-dimethylimidazolium tetrafluoroborate, 1-ethyl-2,3-dimethylimidazolium hexafluoro Phosphate, 1 Butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium nitrate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3 -Methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium nitrate, 1-hexyl-3-methylimidazole Rium tetrafluoroborate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-octyl-3-methylimidazolium bromide, 1-octyl-3-methylimidazolium chloride, 1-octyl-3-methyl Imidazolium nitrate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-methyl-3-octylimidazolium bromide, 1-methyl-3-octylimidazo Lithium chloride, 1-methyl-3-octylimidazolium nitrate, 1-methyl-3-octylimidazolium tetrafluoroborate, 1-methyl-3-octylimidazolium hexafluorophosphate, 1-butyl-4-methylpyridinium bromide 1-butyl-4-methylpyridinium chloride, 1-butyl-4-methylpyridinium nitrate, 1-butyl-4-methylpyridinium tetrafluoroborate, 1-butyl-4-methylpyridinium hex Examples include safluorophosphate, 1-butyl-3-methylimidazolium methyl sulfate, 1-butyl-3-methylimidazolium methylsulfonate, 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, and the like. be able to.

  The melting point of the quaternary salt compound of nitrogen-containing heterocyclic ring that can be used in the present invention is 80 ° C. or lower, more preferably 50 ° C. or lower. When a quaternary salt compound having a low melting point is used, there are advantages that there is no concern about residue precipitation and compatibility is improved in addition to the advantage that developability is improved.

  The content of the quaternary salt compound of the nitrogen-containing heterocyclic ring of the present invention is preferably from 0.1 to 20% by mass, more preferably from 0.5 to 15% by mass, based on the total amount of the recording layer. Within these ranges, developability and compatibility are improved.

[Other polymer compounds]
In the present invention, in addition to the above-described polymer compounds, other polymer compounds can be used in combination. Here, these polymer compounds are described.
The polymer compound used in combination 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 (a) to (e) in the main chain and / or side chain of the polymer.
(A) Sulfonamide group (—SO ₂ NH—R)
(B) Substituted sulfonamide acid group (hereinafter referred to as “active imide group”)
[—SO ₂ NHCOR, —SO ₂ NHSO ₂ R, —CONHSO ₂ R]
(C) Carboxylic acid group (—CO ₂ H)
(D) Sulfonic acid group (—SO ₃ H)
(E) Phosphate group (-OPO ₃ H ₂ )

In the above (a) and (b), R represents a hydrogen atom or an optionally substituted hydrocarbon group.
Examples of the polymer compound having an acidic group selected from the above (a) to (e) include the following.

  (A) As a high molecular compound which has a sulfonamide group, the polymer comprised by making the minimum structural unit derived from the compound which has a sulfonamide group into a main structural unit can be mentioned, for example. 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 them, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group in the molecule is preferable. For example, in the following formulas (i) to (v) And the compounds represented.

(In formulas (i) to (v), X ¹ and X ² each independently represent —O— or —NR ^7. R ¹ and R ⁴ each independently represent a hydrogen atom or —CH ₃ .
R ² , R ⁵ , R ⁹ , R ¹² and R ¹⁶ each independently represent an alkylene group having 1 to 12 carbon atoms, a cycloalkylene group, an arylene group or an aralkylene group. The alkylene group, cycloalkylene group, arylene group and aralkylene group may further have a substituent, and examples of the substituent that can be introduced include a halogen, an alkyl group, a hydroxy group, and a hydroxyalkyl group.
R ³ , R ⁷ and R ¹³ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. The alkyl group, cycloalkyl group, aryl group and aralkyl group may further have a substituent, and examples of the substituent which can be introduced include a halogen, an alkyl group, a hydroxy group and a hydroxyalkyl group.
R ⁶ and R ¹⁷ each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. The alkyl group, cycloalkyl group, aryl group and aralkyl group may further have a substituent, and examples of the substituent which can be introduced include a halogen, an alkyl group, a hydroxy group and a hydroxyalkyl group.
R ⁸ , R ¹⁰ and R ¹⁴ each independently represent a hydrogen atom or —CH ₃ .
R ¹¹ and R ¹⁵ each independently represents a single bond, an alkylene group having 1 to 12 carbon atoms, a cycloalkylene group, an arylene group or an aralkylene group. The alkylene group, cycloalkylene group, arylene group and aralkylene group may further have a substituent, and examples of the substituent that can be introduced include a halogen, an alkyl group, a hydroxy group, and a hydroxyalkyl group.
Y ¹ and Y ² each independently represent a single bond or CO. )

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

  (B) 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.

  (C) 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 used as a main structural unit. A polymer can be mentioned. In the photosensitive lithographic printing plate precursor according to the invention, acrylic acid, methacrylic acid, maleic acid and itaconic acid can be preferably used.

  (D) As a high molecular compound having a sulfonic acid group, for example, a minimum structural unit derived from a compound having one or more sulfonic acid groups and polymerizable unsaturated groups in the molecule is used as a main structural unit. A polymer can be mentioned.

  (E) 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 (a) to (e) 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 the above (a) to (e), (a) a polymer compound having a sulfonamide group, (b) an active imide group and (c) a carboxylic acid group is preferable. The polymer compound having (a) a sulfonamide group or (c) a carboxylic acid group is most preferred.

Further, the minimum structural unit having an acidic group selected from the above (a) to (e) is not particularly limited to one kind, and the minimum structural unit having the same acidic group is two or more, or has different acidic groups. What copolymerized 2 or more types of minimum structural units 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 (a) to (e) to be copolymerized is contained in an amount of 3 mol% or more. % Is more preferable. By setting it as 3 mol or more, the solubility to an alkali developing solution can be improved.

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.

The polymer compound in the present invention may be used alone or in combination, and two or more different polymer compounds may be used in combination.
The recording layer of the photosensitive lithographic printing plate precursor according to the invention may have a laminated structure.
The polymer compound used in the lower layer when the recording layer has a laminated structure is preferably a copolymer having a sulfonamide group and / or a carboxylic acid group, and the copolymer component includes alkyl (meth) acrylate, (Meth) acrylamide, (meth) acrylonitrile, N-phenylmaleimide can be mentioned.

  Also, novolak resins are 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 Any of-/ p-mixing, m- / o-mixing and o- / p-mixing.) Mixed formaldehyde resins are preferred.

  In addition, novolak resin and xylenol resin are preferably used as the polymer compound used in the upper layer of the laminated structure, and 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-xylenol, 3,5-xylenol resin, xylenol / phenol mixed resin, xylenol / novolak mixed resin, xylenol / novolak / phenol mixed resin, etc. Can give.

  When the polymer compound is a novolak resin such as a phenol formaldehyde resin or a cresol formaldehyde resin, a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000 are preferred. More preferably, the weight average molecular weight is 1,000 to 15,000, and the number average molecular weight is 500 to 8,000.

  In the case of polymer compounds other than novolak resins such as phenol formaldehyde resin and cresol formaldehyde resin, those having a weight average molecular weight of 2,000 or more and a number 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 dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10.

  The content of the polymer compound (the total amount of the polymer compound having a phenolic hydroxyl group and other polymer compounds) is 30 to 99% by mass, preferably 50 to 99% by mass, particularly with respect to the total amount of the recording layer. Preferably it is 65-99 mass%. When the content of the polymer compound is within the above range, the heat-sensitive layer has high durability and good sensitivity.

[Infrared absorber]
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 recording layer can be obtained.
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 literature (for example, “Dye Handbook” edited by the Society of Synthetic Organic Chemistry, published in 1970), such as azo dyes, metal complex azo dyes, pyrazolone azos. 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, methine dyes described in JP-A-58-112793, Naphthoquinone dyes described in JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc. Examples thereof include 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, EpolightIII-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 added is preferably 0.01 to 50% by mass, more preferably 0.1 to 10% by mass, based on the total solid content of the recording layer. Moreover, 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. Within the above range, high sensitivity can be obtained, a uniform recording layer can be maintained, and the durability of the recording layer is high.

[Other ingredients]
In the lithographic printing plate precursor according to the invention, an intermediate layer can be provided between the hydrophilic surface of the support and the recording layer as necessary.
By providing the intermediate layer, an infrared photosensitive layer whose solubility in an alkali developer is improved by exposure is provided on the exposed surface or in the vicinity thereof, and the sensitivity to the infrared laser becomes better. In addition, if an intermediate layer made of a polymer is provided between the support and the infrared photosensitive layer, the intermediate layer functions as a heat insulating layer, so that the heat generated by the infrared laser exposure is not diffused to the support and is efficient. It has the advantage that it is often used for image formation and can achieve high sensitivity.

In the unexposed area, the recording layer itself that is impermeable to the alkali developer functions as a protective layer for the intermediate layer, so that an image with excellent development stability and excellent discrimination is obtained. It can be formed and stability over time is also ensured.
Furthermore, since the intermediate layer is configured as a layer mainly composed of an alkali-soluble polymer and has a very good solubility in a developer, by providing such an intermediate layer adjacent to the support, For example, even when a developer with reduced activity is used, when the components of the recording layer whose dissolution-inhibiting ability has been released by exposure are dissolved and dispersed in the developer, no residual film or the like is generated promptly. The exposed portion is removed. This is considered to contribute to the improvement of developability. For these reasons, the intermediate layer is considered useful.

  As described above, the intermediate layer is configured as a layer mainly composed of an alkali-soluble polymer. In order to clarify the boundary between the recording layer and the intermediate layer, the alkali-soluble resin used for the intermediate layer is a recording layer. It is preferable to use, as a main component, a different one from the alkali-soluble resin used in the above.

Various additives can be further added to the coating layer according to the present invention as necessary.
For example, in order to adjust the solubility of the recording layer, other onium salts, aromatic sulfone compounds, aromatic sulfonic acid ester compounds, polyfunctional amine compounds, and the like can be added to add an alkaline water-soluble polymer (alkali-soluble resin). It is preferable to add a so-called dissolution inhibitor that improves the dissolution inhibiting function of the developer in the developer. Among them, those having thermal decomposability such as onium salts, o-quinonediazide compounds, sulfonic acid alkyl esters and the like are preferable, and it is possible to use in combination with a substance that substantially reduces the solubility of the alkali-soluble resin when not decomposed. Is preferable in that it can control the dissolution inhibiting property of the developer in the developer.

  Preferred examples of the onium salt used in the present invention include S.P. 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, U.S. Pat. Nos. 4,069,055, 4,069,056, and 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. et al. 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 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 used in the present invention include J. 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 content of the onium salt and / or o-quinonediazide compound, which is a degradable dissolution inhibitor, is preferably 1 to 10% by mass, more preferably 1 to 5% by mass, and particularly preferably 1 to 5% by mass with respect to the total amount of the recording layer. The range is 2% by mass. These compounds can be used alone, but may be used as a mixture of several kinds.
The content 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.

  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.

Moreover, the photosensitive lithographic printing plate precursor according to the invention may contain cyclic acid anhydrides, phenols, and organic acids for the purpose of improving sensitivity. Further, a surfactant, an image colorant, and a plasticizer described later can also be used in the positive recording layer of the present invention.
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. Examples thereof include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755.

The content of the cyclic acid anhydride, phenols, and organic acids is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, and particularly preferably 0. 0% by mass, based on the total amount of the recording layer. 1 to 10% by 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 image colorant, other dyes can be used in addition to the above-mentioned 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.
Suitable pigments include phthalocyanine pigments, azo pigments, carbon black, titanium oxide, silica particles and the like.

The content of the dye is preferably 0.01 to 10% by mass, more preferably 0.1 to 3% by mass, based on the total amount of the recording layer.
Further, the content of the pigment is preferably from 0.01 to 10% by mass, more preferably from 0.1 to 3% by mass, based on the total amount of the recording layer.

  Furthermore, the photosensitive lithographic printing plate precursor according to the present invention may contain a plasticizer for imparting flexibility of the coating film, if necessary. 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]
A recording layer can be produced by dissolving the photosensitive composition of the present invention in a solvent and coating it on a suitable support. Further, depending on the purpose, a protective layer, a resin intermediate layer, a backcoat layer, and the like 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 can be used alone or in combination.

Content of the said component (total solid content including an additive) in a solvent becomes like this. Preferably it is 1-50 mass%, More preferably, it is 3-30 mass%.
Moreover, 0.3-5.0 g / m < ² > is preferable and, as for the solid content coating amount on the support body obtained after application | coating and drying, More preferably, it is 0.5-3.0 g / m < ² >.

  Various methods can be used for applying the recording layer coating liquid. For example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, roll coating, etc. Can be mentioned. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the photosensitive film deteriorate.

[Support]
The support used in the lithographic printing plate precursor using the photosensitive composition according to the present invention is a dimensionally stable plate-like material that satisfies the required physical properties such as strength and flexibility. There is no particular limitation as long as it is, for example, paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), metal plate (for example, aluminum, zinc, copper, etc.), plastic film (for example, cellulose diacetate, Cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which a metal as described above is laminated or vapor-deposited Etc.

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 the different elements in the alloy is preferably 10% by mass or less, and more preferably 5% by mass or less.

Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements.
Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.12 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.

〔exposure〕
The lithographic printing plate precursor using the photosensitive composition of the present invention is image-formed by heat. Specifically, direct image-like recording using a thermal recording head, scanning exposure using an infrared laser, high-illuminance flash exposure such as a xenon discharge lamp, infrared lamp exposure, and the like are used, but a semiconductor that emits infrared light having a wavelength of 700 to 1200 nm. Exposure by a solid high-power infrared laser such as a laser or a YAG laser is suitable.
The laser output 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〕
In the present invention, the exposed photosensitive lithographic printing plate precursor is preferably developed with an alkaline aqueous solution having a pH of 12 or more 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 mass or less, preferably 0.3% by mass 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 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 former, the aqueous solution of alkali metal silicate is a ratio of silicon oxide SiO ₂ which is a component of silicate and alkali metal oxide M ₂ O (generally expressed as a molar ratio of [SiO ₂ ] / [M ₂ O]. ) And the density, the developability can be adjusted. For example, as disclosed in JP-A-54-62004, the SiO ₂ / Na ₂ O molar ratio is 1.0 to 1.5 (that is, [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 mass% is disclosed in JP-B-57-7427. As described, [SiO ₂ ] / [M] is 0.5 to 0.75 (ie, [SiO ₂ ] / [M ₂ O] is 1.0 to 1.5), and SiO ₂ The developer is based on gram atoms of all alkali metals present in the developer. A manner containing potassium at least 20%, aqueous solution of an alkali metal silicate is preferably used.

  In addition, a so-called “non-silicate developer” that does not contain an alkali silicate and contains a non-reducing sugar and a base can also be suitably used. In this case, 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 within the above range, an appropriate buffer action is obtained.

  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, published by Pergmon Press.

  Specifically, alcohols such as 2,2,3,3-tetrafluoropropanol-1, trifluoroethanol and trichloroethanol, aldehydes such as pyridine-2-aldehyde and pyridine-4-aldehyde, 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-cresol , Compounds having a phenolic hydroxyl group such as resorsonol, oximes such as acetoxime, 2-hydroxybenzaldehyde oxime, dimethylglyoxime, ethanediamide dioxime, acetophenone oxime, adenosine, inosine, guanine, cytosine, hypoxanthine, xanthine Nucleic acid-related substances such as down, the other, diethylaminomethyl acid, benzimidazole, and the like barbituric acid is preferably exemplified.

  To the developer and replenisher, various surfactants and organic solvents are added as necessary for the purpose of promoting and suppressing developability, dispersing development residue, or improving ink affinity of the printing plate image area. it can. 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 image forming material developed using the developer and the replenisher is post-processed 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 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, 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 water-washing water, a rinsing solution containing a surfactant and the like, a desensitizing solution containing gum arabic and starch derivatives. 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.

  In the lithographic printing plate precursor using the photosensitive composition of the present invention, an image portion unnecessary for the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming (for example, If there is a film edge mark of the original image film, 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 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.

As its method, with a sponge or absorbent cotton soaked with the surface-adjusting liquid, it is applied onto a lithographic printing plate, or a method in which the printing plate is immersed and applied 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 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.). The 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 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, a so-called desensitizing treatment such as gumming can be omitted. 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]
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, desmutting treatment was performed 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.
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 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 was etched by spraying at 32 ° C. with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass, the aluminum plate was dissolved at 0.10 g / m ² , and electrochemical using the previous AC. The smut component mainly composed of aluminum hydroxide generated during the 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.
A desmut treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid at a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), and then water washing by spraying was performed 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.
As described above, a support for a photosensitive lithographic printing plate was obtained.
On the hydrophilic surface of the obtained support, the following photosensitive layer solution A is applied and dried in an oven at 150 ° C. for 1 minute, whereby a positive layer having a photosensitive layer with a dry film thickness of 1.8 g / m ² is obtained. A lithographic printing plate precursor was prepared.

<Photosensitive layer solution A>
-Novolak resin 1 with m-cresol / p-cresol = 60/40 (molar ratio)
(Weight average molecular weight 6,000) 10.00 g
1-butyl-3-methylimidazolium tetrafluoroborate (melting point: -75 ° C.)
0.03g
-15.00 g of a solution of the copolymer (3) described in the text obtained in Synthesis Example 1
・ Dye with Victoria Pure Blue BOH counter anion as 1-naphthalenesulfonic acid
0.04g
・ F-780-F (Dainippon Ink & Chemicals, Inc. fluorine-based surfactant) 0.03 g
・ Methyl ethyl ketone 37.2g
・ 37.2 g of 1-methoxy-2-propanol
・ The following infrared absorber (cyanine dye A) 0.50 g
In this way, a photosensitive lithographic printing plate (A) was obtained.

[Example 2]
In Example 1, instead of the copolymer (3) of the photosensitive layer, a copolymer (1) synthesized in the same manner as in Synthesis Example 1 was used. The copolymer (1) was charged with styrene / acrylonitrile / 2-hydroxyethyl methacrylate = 30/50/20 (weight ratio), and the weight average molecular weight of the obtained copolymer was 10,000. Other than that was carried out similarly to Example 1, and obtained the photosensitive lithographic printing plate (B).

[Example 3]
In Example 1, a copolymer (4) synthesized in the same manner as in Synthesis Example 1 was used instead of the copolymer (3) of the photosensitive layer. This copolymer (4) was charged with styrene / acrylonitrile / polyethylene glycol methyl ether methacrylate = 60/30/10 (weight ratio), and the weight average molecular weight of the obtained copolymer was 50,000. Here, an average of 25 repeating units of polyethylene glycol were used. Further, in place of the novolak resin 1, a novolak resin 2 (weight average molecular weight 8,000) of phenol / m-cresol / p-cresol = 50/30/20 (molar ratio) was used. Otherwise in the same manner as in Example 1, a photosensitive lithographic printing plate (C) was obtained.

[Example 4]
In Example 1, instead of the copolymer (3) of the photosensitive layer, the copolymer (5) synthesized in the same manner as in Synthesis Example 1 was used. This copolymer (5) was charged with styrene / acrylonitrile / 2-hydroxyethyl methacrylate / polyethylene glycol methacrylate = 50/35/10/5 (weight ratio), and the resulting copolymer had a weight average molecular weight of 60, 000. Here, an average of 12 repeating units of polyethylene glycol was used. Other than that was carried out similarly to Example 1, and obtained the photosensitive lithographic printing plate (D).

[Example 5]
In Example 1, 1-methyl-3-octylimidazolium tetrafluoroborate (melting point: -88 ° C.) was used instead of 1-butyl-3-methylimidazolium tetrafluoroborate in the photosensitive layer. Otherwise in the same manner as in Example 1, a photosensitive lithographic printing plate (E) was obtained.

[Example 6]
In Example 1, the amount of the copolymer (3) in the photosensitive layer was 10 g, and a copolymer of N-phenylmaleimide / methacrylamide / methacrylic acid = 45/35/20 (molar ratio) (weight average molecular weight 50). , 000) was used. Otherwise in the same manner as in Example 1, a photosensitive lithographic printing plate (F) was obtained.

[Example 7]
In Example 1, instead of the copolymer (3) of the photosensitive layer, the copolymer (6) synthesized in the same manner as in Synthesis Example 1 was used. The copolymer (6) was charged with styrene / polyethylene glycol methyl ether methacrylate = 70/30 (weight ratio), and the weight average molecular weight of the obtained copolymer was 20,000. The average number of polyethylene glycol repeating units was 12. Other than that was carried out similarly to Example 1, and obtained the photosensitive lithographic printing plate (G).

[Comparative Example 1]
In Example 1, the copolymer (3) of the photosensitive layer was not added, and the amount of the novolak resin 1 was 15 g. Other than that was carried out similarly to Example 1, and produced the photosensitive lithographic printing plate (H).

[Comparative Example 2]
In Example 1, the photosensitive layer 1-butyl-3-methylimidazolium tetrafluoroborate was not added. Other than that was carried out similarly to Example 1, and produced the photosensitive lithographic printing plate (I).

[Evaluation of lithographic printing plate precursor]
[Evaluation of sensitivity]
The obtained lithographic printing plate precursor was subjected to drawing of a test pattern in an image by changing the exposure energy with a Trend setter manufactured by Creo.
Then, using a PS processor 900H manufactured by Fuji Photo Film Co., Ltd., the liquid temperature was kept at 30 ° C., and development was performed for 20 seconds. At this time, as the developer, a developer DP-4 manufactured by Fuji Photo Film Co., Ltd. and tap water were mixed and diluted at a predetermined ratio, and a developer DT-2 manufactured by Fuji Photo Film Co., Ltd. and tap water were used. Two types of water mixed with water and diluted to have an electric conductivity of 43 mS / cm are used. As the gum solution, a predetermined ratio of gum solution FP-2W manufactured by Fuji Photo Film Co., Ltd. and tap water is used. What was mixed and diluted with was used. At this time, the exposure energy at which the non-image area can be completely developed was measured and used as sensitivity. A smaller value means higher sensitivity. The results are shown in Table 1.

[Evaluation of developability]
Except for using an exposure energy of 300 mJ / cm ² and using a developer obtained by mixing and diluting a developer DT-2 manufactured by Fuji Photo Film Co., Ltd. and tap water, the same processing as in the sensitivity evaluation was performed. went. At this time, the degree of dilution of the developer was changed and decreased from 45 mS / cm to 2 mS / cm, and the conductivity at which development could no longer be performed was measured. A smaller value means better developability. The results are shown in Table 1.

[Evaluation of printing durability]
Except that the exposure energy was 300 mJ / cm ² , and the developer to be used was mixed with developer DT-2 manufactured by Fuji Photo Film Co., Ltd. and tap water and diluted to have an electrical conductivity of 43 mS / cm. The treatment was performed in the same manner as the sensitivity evaluation, and printing was performed using the obtained lithographic printing plate. At this time, the printer is a Lislon printer manufactured by Komori Corporation, the ink is GEOS (N) ink manufactured by Dainippon Ink and Chemicals, and the dampening water is 1% EU-3 from Fuji Photo Film Co., Ltd. And water containing 5% of IPA were used. 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. It means that printing durability is so good that a numerical value is large. The results are shown in Table 1.

As shown in Table 1, the lithographic printing plate of the present invention has high sensitivity, can be developed with a developer with low conductivity, and has excellent printing durability when using any of two types of developers. I found out.
On the other hand, the lithographic printing plate of the comparative example is inferior to the lithographic printing plate of the present invention in terms of sensitivity, developability and printing durability. Comparative Example 1 not containing a copolymer having a specific structure is particularly inferior in terms of printing durability, and Comparative Example 2 not containing a nitrogen-containing heterocyclic quaternary salt compound is particularly sensitive and developable. It was greatly inferior in respect.

Claims (1)

  On the surface of a support having hydrophilicity, a polymer compound having a phenolic hydroxyl group, an infrared absorber, a quaternary salt compound of a nitrogen-containing heterocyclic ring, and a polymerizable monomer having a styrene and an ethylene oxide group are included as structural units. A photosensitive lithographic printing plate precursor for infrared laser, comprising a recording layer containing a vinyl copolymer.