JP4732108B2 - Planographic printing plate manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a lithographic printing plate, and more particularly to a method for producing a printing plate using an infrared laser.

  In recent years, a laser input method has become mainstream as a system for making a plate directly from digital data of a computer. In particular, solid lasers and semiconductor lasers having a light emitting region from near infrared to infrared are readily available in high output and small size, and are therefore adaptable to such exposure light sources and printing. There is a growing demand for lithographic printing plate materials with excellent suitability.

  In recent years, there has been a growing demand for lithographic printing plate materials that are adaptable to such exposure light sources and that have excellent printing durability. As one of the plate materials used for direct plate making to which the exposure light source as described above is applied, there is a positive lithographic printing plate material for infrared laser.

  The positive type lithographic printing plate precursor for infrared laser has an alkaline aqueous solution-soluble binder resin, an IR dye that absorbs light and generates heat, and the like as essential components. In the non-exposed 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.

The performance required for the positive type lithographic printing plate precursor includes, for example, developability of the exposed portion, printing durability of the obtained lithographic printing plate, chemical resistance to a plate cleaner used during printing, high resistance, etc. There are halftone dot reproducibility during light exposure and cleaner resistance. In response to such demands, a photosensitive composition in which an alkali-soluble resin contained in a photosensitive layer (recording layer) is improved, and a lithographic printing plate using the composition as a recording layer have been proposed ( For example, see Patent Document 1), although the level of cleaner resistance is improved, there are problems that burning printing durability and halftone dot reproducibility during highlight exposure are low, cleaner resistance, burning printing durability, In addition, satisfactory lithographic printing plates were not obtained for all of the halftone dot reproducibility.
European Patent Application No. 1506858

The present invention has been made to overcome the above-mentioned drawbacks of the prior art, and aims to achieve the following objects.
That is, an object of the present invention is to provide a method for producing a lithographic printing plate excellent in cleaner resistance, burning printing durability, and dot reproducibility.

As a result of intensive studies, the present inventors have found conditions for achieving the above-mentioned object.
That is, the present invention has a recording layer containing an alkali-soluble resin containing a monomer unit having a phenyl group substituted by a substituent represented by the following general formula (1) and an infrared absorber on a support. The step of drying the recording layer after coating the recording layer on the support includes a heat treatment for maintaining a temperature condition of 150 ° C. or more and 250 ° C. or less for 0.1 second or more and 60 seconds or less. This is a method for producing a lithographic printing plate.

In the general formula (1), Z ¹ , Z ² and Z ³ each independently represent a monovalent substituent composed of a hydrogen atom or a nonmetallic atom.

  In the lithographic printing plate production method of the present invention, the drying step is a range of an average cooling rate of 5 ° C./second to 30 ° C./second until the temperature of the recording layer reaches 40 ° C. after the heat treatment. A cooling process of cooling at an average cooling rate within the range may be included.

Although the operation of the present invention is not clear, it is presumed as follows.
In the lithographic printing plate produced by the lithographic printing plate production method according to the present invention, the solubility of the recording layer in an alkaline developer is lowered, and the strength of the image area is improved. The reason for this is not clear, but depending on the drying conditions in the drying process of the present invention, the strength of the entire recording layer due to the interaction between alkali-soluble resins (hereinafter referred to as “specific alkali-soluble resins” as appropriate), such as hydrogen bonding. Is improved, and the solubility in an alkaline developer is considered to decrease. Since this interaction is easily released by heat generated by infrared laser exposure, the lithographic printing plate produced by the lithographic printing plate production method of the present invention is particularly excellent in halftone dot reproducibility during highlight exposure. Guessed.
In addition, the alkali-soluble resin in the recording layer obtained by the heat treatment in the lithographic printing plate manufacturing method of the present invention is likely to progress in three-dimensional structuring at the time of heating, and the recording layer strength by the heat treatment is likely to be improved. For this reason, it is presumed to have excellent properties in burning press life.

  According to the method for producing a lithographic printing plate of the present invention, the step of drying the recording layer after coating the recording layer on the support is performed at a temperature of 150 ° C. to 250 ° C. for 0.1 seconds to 60 seconds. Therefore, a method for producing a lithographic printing plate having high sensitivity, excellent resistance to cleaner, burning printing durability and halftone dot reproducibility during highlight exposure can be provided.

The present invention will be described in detail.
The method for producing a lithographic printing plate of the present invention comprises, on a support, an alkali-soluble resin containing a monomer unit having a phenyl group substituted by a substituent represented by the following general formula (1), and an infrared absorber. The step of drying the recording layer after coating the recording layer on the support and maintaining the temperature condition of 150 ° C. or higher and 250 ° C. or lower for 0.1 second or longer and 60 seconds or shorter Including heat treatment.

[Alkali-soluble resin]
The alkali-soluble resin used in the present invention includes a monomer unit having a phenyl group substituted with a substituent represented by the following general formula (1).

In the general formula (1), Z ¹ , Z ² , and Z ³ each independently represent a monovalent substituent composed of a hydrogen atom or a nonmetallic atom.
The monovalent substituent composed of a nonmetallic atom represented by Z ¹ , Z ² , or Z ³ is preferably a substituent composed of a linking site and a terminal site. In addition, a connection site | part is used as needed, and the monovalent substituent consisting of a nonmetallic atom may be formed only from the terminal site.
Moreover, the monovalent substituent consisting of a nonmetallic atom may be further substituted with an alkyl group or an aryl group.

The linking moiety, alkylene group, an alkenylene group, phenylene, arylene groups such as naphthalene, pyridyl, pyrazinyl, pyrimidyl, heterocyclic group containing a heteroatom such as _{thiazolyl, - (C 2 H 4 O} ) n - group (n = _{1~12), - (C 2 H} 4 S) n - group (n = 1~12), - Ph -NHSO 2 - group, or include a combination of these.

As the terminal portion, a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkyl group, an unsaturated cyclic hydrocarbon group, an aryl group, a heterocyclic group, an aralkyl group, -OR ^1, -SR ^1, - ^{COOR 1, -O-COR 1,} -CO-R 2, -SO 3 -R 1, -SO 2 -R 1, -CN, -NO 2, a halogen atom, a phosphate group, phosphonate group, t-amine group, Examples include an amide group, an imide group, and a sulfonamide group. Here, R ¹ and R ² are each independently a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkyl group, an unsaturated cyclic hydrocarbon group, an aryl group, a heterocyclic group, or an aralkyl group. , Selected from amine groups.

  The preferable structure of the alkali-soluble resin containing a monomer unit having a phenyl group substituted by the substituent represented by the general formula (1) is specifically represented by the following general formula (2). The present invention is not limited to these.

In the general formula (2), Z ^1, Z ^2, and Z ^3, Z ^1, Z ² in the general formula (1), and Z ³ are dove synonymous, and preferred ranges are also the same. In general formula (2), R represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms, and is preferably an alkyl group having 5 or less carbon atoms. Examples of each substituent R, Z ¹ , Z ² , and Z ^{3 in} the general formula (2) are shown in Tables 1 to 4 below.
Incidentally, R shown in Table 1 to Table 4, Z ^1, Z ^2, and Z ³ may be combined with each other arbitrarily.

  Specific examples of the alkali-soluble resin suitably used for the lithographic printing plate precursor according to the invention are listed in Table 5 below, but the invention is not limited thereto.

  The method for synthesizing the specific alkali-soluble resin according to the present invention is not particularly limited. For example, in order to substitute a part of the substituent of the phenol resin having a phenoxide substituent with the specific substituent, , Sn metal as a catalyst can be produced by reacting with an isocyanate group (nucleophilic addition reaction). The nucleophilic addition reaction between the phenoxide of the novolak-type phenol resin and the isocyanate group-containing compound can be performed as follows. That is, the total weight of the novolak-type phenol resin for substituting a part of the hydroxyl group with a specific functional group is dissolved in a solvent so as to have a concentration of 20 to 80% by mass (preferably 30 to 70% by mass). With respect to the total number of moles of hydroxyl groups of the novolak-type phenol resin, the isocyanate group-containing compound is added so that the mole ratio thereof is a mole ratio to be substituted with a specific functional group, and further, the mole of the isocyanate group-containing compound using Sn metal as a catalyst. It is added under temperature conditions in the range of 10 ° C. to 200 ° C. so that the molar ratio to the number is 0.5 to 5.0% (preferably 1.0 to 2.5), and the number is maintained while maintaining the temperature range. This can be done by stirring for a period of time. In addition, it is preferable that reaction temperature is the range of 20 to 150 degreeC, and it is more preferable that it is the range of 20 to 100 degreeC. In this case, examples of the solvent used in the above reaction include chloroform, dichloromethane, dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF), dimethyl ether (DME), tetrahydrofuran (THF), and the like. Tetrahydrofuran (THF) is preferably used. As the Sn metal, dibutyltin dilaurate is preferably used.

  The molecular weight of the specific alkali-soluble resin is preferably 2000 or more in terms of weight average molecular weight, and more preferably in the range of 3000 to 500,000. Moreover, in number average molecular weight, 1000 or more are preferable and the inside of the range of 2000-400,000 is more preferable.

The content of the specific alkali-soluble resin in the composition constituting the recording layer of the lithographic printing plate precursor used in the present invention is preferably 30 to 98% by mass, more preferably 25 to 90% by mass in terms of solid content. It is a range.

  Moreover, in this invention, other alkali-soluble resin other than the said specific alkali-soluble resin can also be used together. Other alkali-soluble resins other than the specific alkali-soluble resin can be used in the total alkali-soluble resin at about 1 to 90% by mass, preferably about 5 to 50% by mass.

The other alkali-soluble resin that can be used in combination is not particularly limited as long as it has a property of dissolving when contacted with an alkaline developer, but contains an acidic group in the main chain and / or side chain in the polymer. It is preferable that the polymer is a homopolymer, a copolymer thereof, or a mixture thereof.
Among them, as other alkali-soluble resins that can be used in combination, resins having an acidic group listed in the following (1) in the main chain and / or side chain of the polymer, and acidic groups listed in the following (2) to (6): What is contained in the main chain and / or side chain of the polymer is preferable in terms of solubility in an alkaline developer and expression of dissolution inhibiting ability.

(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) Phosphate 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 hydrogen atom or a hydrocarbon group which may have a substituent. .

  Among the alkali-soluble resins having an acidic group selected from the above (1) to (6), (1) an alkali-soluble resin having a phenol group, (2) a sulfonamide group, and (3) an active imide group is preferable. An alkali-soluble resin having (1) a phenol group or (2) a sulfonamide group is most preferable from the viewpoint of sufficiently ensuring solubility in an alkaline developer, development latitude, and film strength.

Examples of the alkali-soluble resin having an acidic group selected from the above (1) to (6) include the following.
(1) Examples of the alkali-soluble resin having a phenol group include those excluding the above-mentioned novolak resin. For example, a pyrogallol acetone resin or a polymer compound having a phenolic hydroxyl group in the side chain can be used. As the polymer compound having a phenolic hydroxyl group in the side chain, a polymerizable monomer comprising a low molecular compound having at least one phenol group and at least one polymerizable unsaturated bond is homopolymerized, or other polymerizable property is used for the monomer. Examples thereof include a polymer compound obtained by copolymerizing monomers.
Examples of the polymerizable monomer include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, or hydroxystyrene having a phenol group.

  (2) As an alkali-soluble resin having a sulfonamide group, for example, a polymer composed of a minimum constituent unit derived from a compound having a sulfonamide group as a main constituent can be mentioned. 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. Of these, low molecular weight compounds having an acryloyl group, an aryl 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 general formulas (i) to (v) The compound represented by these is mentioned.

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

  Among the compounds represented by the general formulas (i) to (v), in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) acrylamide and the like. It can be preferably used.

  (3) As an alkali-soluble resin having an active imide group, for example, a polymer composed of a minimum constituent unit derived from a compound having an active imide group as a main constituent can be mentioned. 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 an alkali-soluble resin 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 constituent component. A polymer can be mentioned.
(5) As an alkali-soluble resin 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.
(6) As an alkali-soluble resin having a phosphate group, for example, a minimum structural unit derived from a compound having at least one phosphate group and a polymerizable unsaturated group in the molecule is used as a main constituent component. A polymer can be mentioned.

  The minimum constitutional unit having an acidic group selected from the above (1) to (6), which constitutes another alkali-soluble resin that can be used in combination, does not have to be only one kind, and is the smallest constitutional unit having the same acidic group. Two or more units or a copolymer obtained by copolymerizing two or more minimum structural units having different acidic groups can also be used.

  When the other alkali-soluble resin that can be used in combination is a copolymer, a compound having an acidic group selected from (1) to (6) serving as a copolymer component is contained in the copolymer in an amount of 10 mol% or more. What is contained is preferable, and what is contained 20 mol% or more is more preferable. If it is less than 10 mol%, the development latitude tends not to be sufficiently improved.

  Moreover, when the alkali-soluble resin which can be used together is a copolymer, the other compound which does not contain the acidic group of said (1)-(6) can also be used as a copolymerization component. Examples of other compounds not containing an acidic group of (1) to (6) include the compounds listed in the following (m1) to (m12), but are not limited thereto.

(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, and glycidyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.

(M5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(M6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(M7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene.
(M8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(M9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(M10) N-vinylpyrrolidone, acrylonitrile, methacrylonitrile and the like.
(M11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.
(M12) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.

  Such other alkali-soluble resins that can be used in combination are preferably a polymerizable monomer having a phenolic hydroxyl group or a homopolymer or copolymer of a polymerizable monomer having an active imide group, and particularly m-aminosulfonylphenyl. A homopolymer or copolymer of a polymerizable monomer having a sulfonamide group, such as methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) acrylamide or the like is preferable. The weight average molecular weight is preferably 2,000 or more and the number average molecular weight is 500 or more. More preferably, the weight average molecular weight is 5,000 to 300,000, the number average molecular weight is 800 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10. . In the present invention, when the alkali-soluble resin is a resin such as a phenol formaldehyde resin or a cresol aldehyde resin, the weight average molecular weight is 500 to 20,000, and the number average molecular weight is preferably 200 to 10,000. .

  Moreover, these alkali-soluble resins that can be used in combination may be used alone or in combination of two or more.

[Infrared absorber]
The recording layer of the lithographic printing plate precursor according to the invention contains an infrared absorber. The infrared absorber that can be used here is not particularly limited as long as it is a substance that absorbs light energy radiation and generates heat, but is compatible with easily available high-power lasers. From the viewpoint of the above, preferred are various dyes or pigments known as infrared absorbing dyes or pigments having an absorption maximum at a wavelength of 700 nm to 1200 nm.

  As such an 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 Technology 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 polymer-bonded pigments. 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, and carbon black.

  The pigment may be used without surface treatment or may be used after 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 Applications of Metal Soap” (Sachishobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). .

  The particle diameter of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. When the particle size of the pigment is less than 0.01 μm, it may not be preferable in terms of the stability of the dispersion in the recording layer coating solution, whereas when it exceeds 10 μm, the recording layer is uniform. It is not preferable in terms of sex.

  As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Dispersers 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, and a pressure kneader are used for the dispersion. . Details of the dispersion method are described in "Latest Pigment Application 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), 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 suitably used as the pigment that absorbs 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. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc., 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 Japanese Utility Model Laid-Open No. 58-112792, and cyanine dyes described in British Patent 434,875.

  As the dye, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also suitable. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, JP-A-58-220143, JP-A-59 No. 41363, JP-A-59-84248, JP-A-59-84249, JP-A-59-146063, and JP-A-59-146061, Pyryllium compounds described in JP-A-59- No. 216146, a pentamethine thiopyrylium salt described in U.S. Pat. No. 4,283,475, JP-B-5-13514, JP-A-5-19702 Pyrylium compounds disclosed, 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.

  Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferable, and one particularly preferable example is a cyanine dye represented by the following general formula (3).

一般式(３)

General formula (3)

In General Formula (3), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. W ¹⁻ is defined in the same manner as Xa ⁻ described later, and R ^a represents a substituent selected from a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom.

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring or It is particularly preferable that a 6-membered ring is formed.

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

  The addition amount of the pigment or dye used as the infrared absorber is preferably 0.01 to 50% by mass, more preferably 0.1 to 10% by mass with respect to the total solid content of the composition constituting the recording 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 addition amount of the pigment or dye is within the above range, excellent uniformity and durability of the recording layer can be obtained together with preferable recording sensitivity when used as a positive recording layer.

[Other additive components]
In the recording layer of the lithographic printing plate precursor according to the invention, various known additive components can be used in combination with the above-mentioned components as required, depending on the purpose.

  For example, in order to adjust the solubility of the recording layer, an onium salt, an aromatic sulfone compound, an aromatic sulfonic acid ester compound, a polyfunctional amine compound, or the like is added to the developer of an alkali water-soluble polymer (alkali-soluble resin). It is preferable to add a so-called dissolution inhibitor that improves the dissolution inhibiting function in the aqueous solution, and among them, onium salts, o-quinonediazide compounds, sulfonic acid alkyl esters, etc. are thermally decomposable, and in the state where they are not decomposed, the alkali-soluble resin is dissolved. It is preferable to use a substance that substantially reduces the property in terms of improving the dissolution inhibition of the image portion 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. 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 8] [Chemical 9] described in 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 amount of the onium salt and / or o-quinonediazide compound that is a degradable dissolution inhibitor is preferably 1 to 10% by mass, more preferably 1 to 5% by mass, particularly preferably the total solid content of the recording layer. Is in the range of 1-2% 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% by mass to 5% by mass, more preferably 0.1% by mass to 2% by mass, and particularly preferably 0.1% by mass to 1.5% by mass. It is in the range of mass%. When the recording layer has a multilayer structure, 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 recording layer according to the present 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 described later can also be used for the recording layer.
Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, 3,6-endooxy-4-tetrahydrophthalic anhydride, and 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, etc. Further, organic acids include The ratios of the sulfonic acids, sulfinic acids, alkyl, and cyclic acid anhydrides, phenols, and organic acids described in Japanese Unexamined Patent Publication No. 60-88942 and Japanese Patent Laid-Open No. 2-96755 are as follows. 0.05 mass% to 20 mass% is preferable, more preferably 0.1 mass% to 15 mass%, and particularly preferably 0.1 mass% to 1 mass%. % 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, JP-A-53-36223, JP-A-54-74728, JP-A-60-3626, JP-A-61-143748, JP-A-61-151644, and JP-A-63-58440 Mention may be made of the combinations of the described trihalomethyl compounds and salt-forming organic dyes. 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. These dyes can be added to the recording layer in a proportion of 0.01% by mass to 10% by mass, preferably 0.1% by mass to 3% by mass, based on the total solid content of the recording layer.

  Furthermore, a plasticizer is added to the recording layer 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 Acid oligomers and polymers are used.

[Preparation of lithographic printing plate precursor]
Hereinafter, preparation of a lithographic printing plate precursor according to the present invention will be described.

(Coating solvent and coating method)
The lithographic printing plate precursor according to the invention can be produced by dissolving the composition constituting the recording layer in a solvent and applying the solution onto a suitable support, and then drying the applied recording layer. 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 for dissolving and coating the recording layer include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2. -Propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, toluene, etc. However, it is not limited to this. These solvents are used alone or in combination.
The concentration of the above components (total solid content including additives) in the solvent is preferably in the range of 1% by mass to 50% by mass.
Coating, the coating amount on the support obtained after drying (solid content) may be varied according to the intended purpose, the amount of coating amount after drying of 0.5mg / m ² ~5.0mg / m ² is preferably , and more preferably it amounts to be ^{0.6mg / m 2 ~2.0mg / m 2} .

  The method for applying the recording layer coating liquid is not particularly limited as long as a uniform coating film having an arbitrary thickness can be formed on the support, and various methods can be used. For example, bar coater coating, spin coating, Examples thereof include spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the photosensitive film deteriorate.

Next, the drying method and heat drying conditions will be described.
As a drying method, a pass roll is arranged in a drying apparatus described in JP-A-6-63487, an arch type dryer that wraps the web on the roll and transports it, and air is supplied from the upper and lower surfaces of the web by a nozzle to feed the web. A method of drying while floating, or a method of heating by using various media without using hot air, and a method of drying by the secondary radiant heat, or a method of heating a roll using various media and contacting the roll and the web There is a method of drying by conduction heat transfer.

In this heating (drying) step, the coating layer of the recording layer has a temperature range of 150 ° C. or more and 250 ° C. or less, or a temperature range of Tg or more and 250 ° C. or less, where Tg is the glass transition point of the binder polymer used. It needs to be heated.
From the viewpoint of the effect, it is preferable that the heating temperature condition is maintained until at least the solvent in the coating film is evaporated and removed and the coating film starts to be cured. It is desirable from the viewpoint of effect to be maintained for less than a second.
Whether or not the solvent has been sufficiently removed from the coating solution can be determined by conventional methods, for example, visual observation of the surface state, palpation of the recording layer coating film taken out from the drying zone, change in vapor pressure in the drying zone, recording layer It can be detected by a determination method such as a change in weight of the support on which the coating liquid is applied. By maintaining the temperature in the temperature range above the predetermined temperature in the vicinity of Tg for a predetermined time, association by hydrogen bonding is sufficiently formed inside the recording layer coating film. If the heating and holding time is too short, this association is not sufficiently formed, and the effect of improving the development latitude becomes insufficient.

The temperature of the recording layer is preferably in the temperature range from 150 ° C. to 250 ° C., more preferably in the temperature range from 160 ° C. to 230 ° C., and particularly preferably in the temperature range from 170 ° C. to 200 ° C.
When the heating temperature is less than 150 ° C., sufficient association of strong hydrogen bonds generated in the production process of the recording layer is not formed, and when the heating temperature is higher than 250 ° C., the photothermal conversion contained in the recording layer coating liquid. Ingredients such as IR dyes are easily decomposed, and polymer film-forming properties are liable to be lowered.

The heating temperature condition is preferably maintained for 0.1 second to 60 seconds,
It is more preferable to maintain for 0.5 second or more and 55 seconds or less, and it is especially preferable to maintain for 1 second or more and 50 seconds or less.
When the heating temperature condition is maintained for less than 0.1 seconds, there is a problem that the effect of the present invention is not manifested due to insufficient heating. There is a problem that deformation and alteration occur.

Next, a method using hot air will be specifically described with reference to the drawings.
FIG. 1 is a schematic sectional view showing an example of a drying apparatus used in the present invention. The long aluminum web 221 guided by the guide roll R and continuously running is coated with a coating solution containing a solvent by the coating unit 222 and introduced into the first step drying zone 23. An air supply port 225 and an exhaust port 226 are provided in the first step drying zone 223. Hot air supplied from the air supply port 225 at 40 ° C. to 130 ° C. and a dew point of −5 to 15 ° C. is rectified by the rectifying plate 229, and the wind speed of 0.5 is applied to the surface of the coating film formed on the aluminum web 221 by the coating. The coating film is contacted at ˜4 m / s, dried, and discharged from the exhaust port 226. The coating film of the aluminum web 221 that has reached the vicinity of the outlet of the first step drying zone 223 exhibits a soft film state. Subsequently, the long aluminum web 221 continuously guided by the guide roll R is introduced into the second step drying zone 224. An air supply port 227 and an exhaust port 228 are provided in the second step drying zone 224.

At least in this drying zone, the coating film of the recording layer is maintained at a temperature condition equal to or higher than the glass transition point (Tg) of the resin used. Here, when a novolac resin is used for the polymer, the Tg is 90 to 100 ° C., so the temperature of the hot air supplied from the air supply port 227 is 100 to 170 ° C. in order to heat the recording layer to the temperature or higher. The dew point is adjusted to a range of 5 to 20 ° C. This hot air is blown out from the slit type nozzle 230 at a blowing air speed of 5 to 15 m / s and comes into violent contact with the coating film surface of the aluminum web 221. As a result, the solvent of the coating film evaporates and the coating film is cured. The gas after coming into contact with the coating film is discharged from the exhaust port 228. In the case of the batch type, the time for placing in the second step drying zone is adjusted, and in the case of the continuous type, the conveying speed of the support is adjusted to keep the recording layer within the above temperature range for a predetermined time. What is necessary is just to adjust so that it may be hold | maintained. The difference between the hot air temperature and the recording layer temperature increases as the conveyance speed of the aluminum support increases and the thickness and width of the support increase. Under general conditions, the recording layer temperature is 5 to 40 ° C. Becomes lower.
As a slit type nozzle, the tip nozzle clearance is usually 0.2 to 8 mm, the pitch 30 to 300 mm, and the nozzle-web distance 5 to 200 mm.

  After the heat treatment as described above is completed, the recording layer is cooled to room temperature. In this cooling treatment, when the temperature is lowered from the heating temperature, the average cooling rate is 5 ° C./until the temperature of the recording layer reaches 40 ° C. It is preferable to perform rapid cooling at an average cooling rate within a range of from 2 seconds to 30 ° C./second. Thus, rapid cooling can suppress the deformation / degeneration of the support that occurs during drying and heating.

When the cooling rate is rapidly cooled at a high speed exceeding 30 ° C./second, the association due to the hydrogen bond formed by the heat treatment is destroyed, the stability of the recording layer is lowered, and clear on-off image formation The development latitude is not sufficiently improved. There is no problem when the cooling rate is low, but it is not preferable in terms of workability if it is less than 5 ° C./second.
As specific temperature-decreasing conditions, for example, when a recording layer is formed by a batch coating method, it is preferable to slowly cool the recording layer to 1 to 3 minutes to cool down to 40 ° C. The temperature lowering is preferably performed over about 1 minute. The method of slow cooling is not particularly limited, and examples thereof include a method of controlling the atmospheric temperature after leaving the drying zone and the temperature of the transport roll.

(Layer structure of recording layer)
The recording layer may have any of a single layer structure, a phase separation structure, and a multilayer structure.
As the single-layer recording layer, for example, the photosensitive layer described in JP-A-7-285275 and WO 97/39894 pamphlet, and as the phase-separated recording layer, for example, the photosensitive layer described in JP-A-11-44956. For example, JP-A-11-218914, U.S. Pat. No. 6,352,812 B1, U.S. Pat. No. 6,352,811 B1, U.S. Pat. No. 6,358,669 B1, U.S. Pat. The described photosensitive layer can be used, but is not limited thereto.

  In the case where the recording layer has a multilayer structure, at least the recording layer on the lower layer side than the outermost layer contains an alkali-soluble resin containing a monomer unit having a phenyl group substituted by the substituent represented by the general formula (1). And a step of drying each recording layer after coating each recording layer, and maintaining the temperature condition of 150 ° C. or higher and 250 ° C. or lower for 0.1 second or longer and 60 seconds or shorter. More preferably, all of the recording layers each include an alkali-soluble resin containing a monomer unit having a phenyl group substituted with a substituent represented by the general formula (1), and an infrared absorber. Preferably, the step of drying each recording layer after coating each recording layer includes a heat treatment for maintaining a temperature condition of 150 ° C. or more and 250 ° C. or less for 0.1 seconds or more and 60 seconds or less.

  When the recording layer has a multilayer structure, when the outermost recording layer is worn earlier than the lower recording layer due to friction with paper or the like, the printing durability is determined by the lower recording layer from the outermost layer. Therefore, at least the recording layer lower than the outermost layer contains an alkali-soluble resin containing a monomer unit having a phenyl group substituted by the substituent represented by the general formula (1), and an infrared absorber, The step of drying each recording layer after coating each recording layer includes a heat treatment for maintaining a temperature condition of 150 ° C. or more and 250 ° C. or less for 0.1 seconds or more and 60 seconds or less, thereby increasing the burning durability. A method for producing a lithographic printing plate excellent in the above can be provided.

(Support)
The support used for the lithographic printing plate precursor 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. Paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, Cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper on which a metal as described above is laminated or vapor-deposited, 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 containing aluminum as a main component and containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10% by mass. Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements.
The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

  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. 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 cannot be specified. However, in general, the electrolyte concentration is 1% to 80% by weight solution, the liquid temperature is 5 ° C. to 70 ° C., and the current density is 5 A / dm. ^{2 to} 60 A / dm ² , voltage 1 V to 100 V, and electrolysis time 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.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the support and the recording layer as necessary. By providing this undercoat layer, the undercoat layer between the support and the recording layer functions as a heat insulating layer, and the heat generated by the infrared laser exposure does not diffuse to the support and can be used efficiently. Therefore, there is an advantage that high sensitivity can be achieved. Further, since the recording layer 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 maintained well.
In the unexposed area, the recording layer itself that is impermeable to the alkaline developer functions as a protective layer for the undercoat layer, so that the development stability is good and the image is excellent in discrimination. In the exposed area, the components of the recording layer whose dissolution inhibiting ability has been released are quickly dissolved and dispersed in the developer. Since the undercoat layer itself, which is adjacent to the support, is made of an alkali-soluble polymer, it has good solubility in a developer, for example, even when a developer with reduced activity is used. It is considered that this undercoat layer is useful because it dissolves rapidly without the formation of a film and the like and contributes to the improvement of developability.

  Various organic compounds are used as the primer layer component. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, and phenylphosphonic acid which may have a substituent Organic phosphonic acids such as naphthyl phosphonic acid, alkyl phosphonic acid, glycero phosphonic acid, methylene diphosphonic acid and ethylene diphosphonic acid, phenyl phosphoric acid which may have a substituent, naphthyl phosphoric acid, alkyl phosphoric acid and glycerophosphoric acid Organic phosphoric acid, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid, glycerophosphinic acid and other organic phosphinic acids, glycine and β-alanine amino acids, and triethanolamine hydrochloric acid Has a hydroxy group such as salt -Alanine, and hydrochlorides of amines that may be used in combination of 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.

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 , -CONHR ¹⁶ , -COR ¹⁷ or -CN, or R ¹² and R ¹³ may be bonded to form a ring, and R ^{14 to} R ¹⁷ are each independently an alkyl group or Represents 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 represent a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl. Represents a group, or R ¹⁸ and R ¹⁹ may combine 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 component having an acid group and a component 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. An acid group having an acid dissociation index (pKa) of 7 or more is preferred as the acid group, and 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 salt is an onium group composed of Group V or Group VI atoms, more preferably an onium salt composed of nitrogen, phosphorus or sulfur atoms, and particularly preferably an onium salt composed of nitrogen atoms. It is salt. Specific examples of the monomer having an onium salt 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 within the range of 0.005% by mass to 10% by mass of the organic compound can be applied by various methods. In the latter method, the concentration of the solution is in the range of 0.01% by mass to 20% by mass, preferably 0.05% by mass to 5% by mass, and the immersion temperature is 20 ° C. to 90 ° C., preferably 25 ° C. The immersion time is in the range of ˜50 ° C., and the immersion time is in the range of 0.1 second to 20 minutes, preferably 2 seconds to 1 minute. The solution used for this can be adjusted to a pH range of 1 to 12 with basic substances such as ammonia, triethylamine, potassium hydroxide, and acidic substances such as hydrochloric acid and phosphoric acid. A yellow dye can also be added to improve the tone reproducibility of the image recording material. The coverage of the undercoat ^{layer, 2mg / m 2 ~200mg / m} 2 is is suitable, and preferably from ^{5mg / m 2 ~100mg / m 2} . If the coating amount is less than 2 mg / m ² , sufficient printing durability cannot be obtained. Moreover, even if it is larger than 200 mg / m ^2, it is the same.

  The lithographic printing plate precursor according to the 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. A semiconductor that emits infrared light having a wavelength of 700 nm 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. It is preferable that the exposure time per pixel is preferably within 20μ seconds, it is preferable energy irradiated to the recording material is ^{10mJ / cm 2 ~500mJ / cm 2} .

  The developer that can be applied to the lithographic printing plate precursor according to the invention is a developer having a pH in the range of 9.0 to 14.0, preferably in the range of 12.0 to 13.5. A conventionally known aqueous alkali 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 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 the content of SiO ₂ is 1% by mass to 4% by mass of an aqueous solution of sodium silicate, or Japanese Examined Patent Publication No. 57-7427. As described in the publication, [SiO ₂ ] / [M] is 0.5 to 0.75 (ie, [SiO ₂ ] / [M ₂ O] is 1.0 to 1.5), the concentration of SiO ₂ is to 4 wt% 1 wt%, and the total alkali metal grayed the developing solution is present therein The beam atoms with respect containing potassium at least 20%, aqueous solution of an alkali metal silicate is preferably used.

  Further, a so-called “non-silicate developer” which does not contain an alkali silicate and contains a non-reducing sugar and a base is more preferable for application to the development of the lithographic printing plate material of the present invention. When the development processing of the lithographic printing plate material is performed using this developer, the surface of the recording layer is not deteriorated and the inking property of the recording layer can be maintained in a good state. In addition, the lithographic printing plate precursor obtained by the production method of the present invention has a wider development latitude than a general one, but the non-silicate developer contains a non-reducing sugar having a buffering property that suppresses pH fluctuations. Therefore, it is advantageous compared to the case of using a developing solution containing silicate. For this reason, the reproducibility of the fine area image is further improved by using the non-silicate developer for developing the lithographic printing plate precursor according to the invention. Furthermore, since non-reducing sugars are less likely to contaminate conductivity sensors, pH sensors and the like for controlling liquid activity compared to silicates, non-silicate developers are advantageous in this respect as well. Further, the effect of improving discrimination is remarkable. This is presumably because the contact (penetration) with the developer which is important in the present invention is mild, and the difference between the exposed and unexposed areas is more likely to occur.

  The non-reducing sugar is a saccharide that does not have a free aldehyde group or a ketone group and does not exhibit reducibility, and is a trehalose-type oligosaccharide in which reducing groups are bonded to each other, or a glycoside in which a reducing group and a non-saccharide are bonded to each other. And sugar alcohols reduced by hydrogenation of saccharides and sugars, both of which can be suitably 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% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass. If the content is less than 0.1% by mass, a sufficient buffering effect tends to be not obtained, and if it exceeds 30% by mass, it is difficult to achieve high concentration and the cost tends to increase.

  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, pyridine-2-aldehyde (, aldehydes such as pyridine-4-aldehyde (and the like) , 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 Compounds having a phenolic hydroxyl group such as-, p-cresol, resorsonol, oximes such as acetoxime, 2-hydroxybenzaldehyde oxime, dimethylglyoxime, ethanediamide dioxime, acetophenone oxime, adenosine, inosine, guanine, cytosine, hypoxanthine , Ki Nucleic acid-related substances such as Nchin, 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. Various surfactants and organic solvents can be added to the developer and replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area.
Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. If necessary, the developer and replenisher may contain reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids such as sodium salts and potassium salts, organic carboxylic acids, antifoaming agents, and hard water softeners. It can also be added.
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 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, image portions unnecessary for the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming (for example, film edge traces 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.

[Heat treatment (burning treatment)]
In the present invention, the lithographic printing plate obtained as described above is subjected to heat treatment (burning treatment) after applying a desensitized gum as necessary.

The burning process is performed by heating in a range of 150 ° C. or more and 350 ° C. or less with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.).
The heating temperature is in the range of 150 ° C to 350 ° C, more preferably 160 ° C to 300 ° C, and still more preferably 180 ° C to 270 ° C. The heating time is preferably in the range of 1 minute to 20 minutes, more preferably 1 minute to 15 minutes, and still more preferably 1 minute to 10 minutes.
As for the heating temperature and the heating time, optimum conditions are selected in consideration of the types of components forming the image.

In the burning process, before the burning process, a surface-conditioning liquid 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 process. As the method, a method of applying the surface-adjusting liquid onto the lithographic printing plate 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 The method, the method of apply | coating with an automatic coater, etc. are 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 that has been subjected to the burning treatment can be subjected to conventional treatments such as washing and gumming as necessary, but a surface-conditioning solution containing a water-soluble polymer compound is used. If so, 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.

(Preparation of lithographic printing plate precursors used in Examples 1 to 3 and Comparative Example 1)
(Production of support)
The support body was produced by processing through the process shown below using a JIS-A-1050 aluminum plate with a thickness of 0.3 mm.

(A) Mechanical surface roughening treatment While supplying a suspension of abrasive (silica sand) having a specific gravity of 1.12 and water as a polishing slurry liquid to a surface of an aluminum plate, it is mechanically rotated by a roller-like nylon brush. Roughening was performed. The average particle size of the abrasive was 8 μm, and the maximum particle size was 50 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkali etching treatment The aluminum plate obtained above was sprayed with an aqueous NaOH solution at a temperature of 70 ° C. (concentration 26 mass%, aluminum ion concentration 6.5 mass%) to perform an etching treatment, and the aluminum plate was 6 g / m. ² dissolved. Thereafter, washing with water was performed using well water.

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

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a nitric acid 10.5 g / liter aqueous solution (aluminum ion 5 g / liter) at a temperature of 50 ° C. The AC power supply waveform has an electrochemical surface roughening treatment using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reaches a peak from zero, a DUTY ratio of 1: 1. went. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Thereafter, washing with water was performed using well water.

(E) Alkali etching treatment The aluminum plate was sprayed at a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at 32 ° C. to dissolve the aluminum plate by 0.20 g / m ² , The smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening was used 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.

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

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 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 50 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.

(H) Alkaline etching treatment An aluminum plate is 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, and the aluminum plate is dissolved at 0.10 g / m ² , so 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.

(I) Desmut treatment A desmut treatment by spraying was performed with a 25% by mass aqueous solution of sulfuric acid at a temperature of 60 ° C. (containing 0.5% by mass of aluminum ions), and then water washing by spraying was performed using well water.

(J) Anodizing treatment As the electrolytic solution, sulfuric acid was used. All electrolytes had a sulfuric acid concentration of 170 g / liter (containing 0.5 mass% of aluminum ions), and the temperature was 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 .

<Support A>
The steps (a) to (j) were sequentially performed, and the support A was produced so that the etching amount in the step (e) was 3.4 g / m ² .
<Support B>
A support B was prepared by sequentially performing the steps except for omitting the steps (g), (h), and (i) among the above steps.

<Support C>
A support C was prepared by sequentially performing the steps except that the steps (a), (g), (h), and (i) were omitted from the above steps.
<Support D>
Of the above steps, the steps (a), (d), (e), and (f) are omitted except that the steps are performed in order, and the total amount of electricity in step (g) is 450 C / dm ^2. Thus, a support D was produced.
The support A, the support B, the support C, and the support D obtained as described above were subsequently subjected to the following hydrophilic treatment and undercoating treatment.
[Undercoating]
On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds to obtain a support with an undercoat layer. The coating amount after drying was 15 mg / m ² .
<Undercoat liquid>
・ The following polymer compound (I) 0.3 g
・ Methanol 100g
・ Water 1g

[Formation of recording layer]
Next, the lower layer coating liquid A having the following composition was applied to the support with the undercoat layer obtained above with a wire bar, and the drying / cooling apparatus shown in FIG. Drying and cooling were performed under the described drying / cooling conditions, and the coating amount was 0.85 g / m ² .
The top layer coating solution B having the following composition was applied to the obtained support with a lower layer with a wire bar. After coating, the coating was dried in a drying oven at 140 ° C. for 50 seconds to make a total coating amount of 1.00 g / m ² .
As described above, positive lithographic printing plate precursors used in Examples 1 to 3 and Comparative Examples 1 and 2 were obtained.

<Coating liquid A for lower layer>
-Specific alkali-soluble resin described in Table 6 2.13 g
・ Cyanine dye P (structure shown below) 0.134 g
・ Bis-p-hydroxyphenylsulfone 0.126 g
・ Tetrahydrophthalic anhydride 0.19g
・ 0.008 g of p-toluenesulfonic acid
2-methoxy-4- (N-phenylamino)
Benzenediazonium hexafluorophosphate 0.032 g
・ Ethyl violet-6-naphthalenesulfonic acid 0.078g
・ Fluorosurfactant (Megafac F-780, manufactured by Dainippon Ink & Chemicals, Inc.) 0.023g
・ Γ-butyrolactone 13.16 g
・ Methyl ethyl ketone 25.39g
・ 1-methoxy-2-propanol 12.95 g
<Coating solution B for top layer>
-M-cresol / p-cresol novolak resin (molar ratio 60/40, weight average molecular weight 5,000) 0.341 g
・ Cyanine dye P (the following structure) 0.019 g
・ Methyl ethyl ketone 2.63g
・ 1-methoxy-2-propanol 5.27g

(Preparation of lithographic printing plate precursors used in Examples 4 to 6 and Comparative Examples 3 and 4)
After applying the coating liquid C having the following composition to the support with an undercoat layer obtained by the same method as the lithographic printing plate precursor used in Examples 1 to 3 with a wire bar, the drying / cooling device shown in FIG. Was used for drying / cooling under the conditions shown in Table 6 below to make the total coating amount 1.00 g / m ² .
As described above, positive lithographic printing plate precursors used in Examples 4 to 6 and Comparative Examples 3 and 4 were obtained.

<Coating liquid C>
・ Specific alkali-soluble resins listed in Table 6 below, 0.75 g
-M-cresol / p-cresol novolak resin (molar ratio 60:40, weight average molecular weight 5,000) 0.25 g
・ 0.003 g of p-toluenesulfonic acid
・ Tetrahydrophthalic anhydride 0.03g
・ Cyanine dye P (the above structure) 0.017 g
・ Victoria Pure Blue (Dye with BOH counter anion as 1-naphthalenesulfonic acid anion) 0.015g
・ Γ-Butyllactone 10.00g
・ Methyl ethyl ketone 10.00g
・ 1-methoxy-2-propanol 5.00g

(Preparation of planographic printing plate precursors used in Examples 7 to 9 and Comparative Examples 5 and 6)
The coating liquid D having the following composition was applied with a wire bar to a support with an undercoat layer obtained by the same method as the planographic printing plate precursor used in Examples 1 to 3. After the application, drying / cooling was performed under the conditions shown in Table 6 below using the drying / cooling apparatus shown in FIG. 1, and the total application amount was 1.40 g / m ² .
As described above, positive lithographic printing plate precursors used in Examples 7 to 9 and Comparative Examples 5 and 6 were obtained.

<Coating liquid D>
-Specific alkali-soluble resin 2.072g described in Table 6 below
・ Cyanine dye P (the above structure) 0.052 g
・ Ethyl violet 6-naphthalenesulfonic acid 0.078g
・ Methyl ethyl ketone 25.30g

(Production of planographic printing plates of Examples 1 to 9 and Comparative Examples 1 to 6)
[Exposure / Development]
Each positive lithographic printing plate precursor obtained as described above was exposed to a test image using a Trend setter 800 manufactured by Creo under the conditions of a beam intensity of 10.0 W and a drum rotation speed of 250 rpm.
Each positive type lithographic printing plate precursor after exposure was subjected to an Auto PN85CE (Agfa) charged with a developer “EP26” manufactured by Agfa at 25 ° C. and 0.96 m / min. Developed under conditions.

[Heat treatment (burning treatment)]
About Examples 1-9 and Comparative Examples 1-6, the heat processing were performed at 235 degreeC for 5 minutes with respect to the lithographic printing plate after image development using the following baking gum solutions.
<Baking gum solution>
As a baking gum solution, Burning surface-adjusting solution BC-7 manufactured by Fuji Photo Film Co., Ltd. was used.
As described above, lithographic printing plates of Examples 1 to 9 and Comparative Examples 1 to 6 were obtained.

[Evaluation]
[Evaluation of planographic printing plate precursor]
Next, performance evaluation of the positive planographic printing plate precursors of Examples 1 to 9 and Comparative Examples 1 to 6 was performed. The evaluation test was conducted on the sample stored at 25 ° C. for 14 days after the photosensitive layer was applied.

(Evaluation of cleaner resistance)
A cleaner solution (manufactured by Fuji Photo Film Co., Ltd .: “Plate Cleaner CL2”) was dropped onto the positive type lithographic printing plate precursor, and the density change of the dripping portion after 1 minute was visually compared. The case where there was no change in density was indicated as ◯, the case where the change in density was slightly observed was indicated as Δ, and the case where the change was greatly changed was indicated as x.

(Halftone image reproducibility)
The obtained positive type lithographic printing plate precursor was drawn (exposed) on an image of a STACCATO 20/50% halftone dot test pattern on a Trendsetter 3244 manufactured by Creo under the conditions of a beam intensity of 10.0 W and a drum rotation speed of 250 rpm. . After the above condition exposure, Fuji Photo Film Co., Ltd. developer DT-2 (diluted to a conductivity of 47 mS / cm) and Fuji Photo Film Co., Ltd. finisher FP-2W (diluted 1: 1). The product was developed using a PS processor LP-940H manufactured by Fuji Photo Film Co., Ltd., with a developing temperature of 12 seconds. Thereafter, it was evaluated whether or not the 1% halftone dot portion was missing with a 50 times magnifier. In addition, the thing in which the missing part of the halftone dot part was seen was set as (circle) and the thing in which the missing part of the halftone dot part was seen as x.

(Burning printing durability)
The obtained positive lithographic printing plate precursor was exposed with a Trend setter 3244 manufactured by Creo under the conditions of a beam intensity of 10.0 W and a drum rotation speed of 250 rpm, and an Autolite PN85CE charged with Agfa developer EP26 was used. 25 ° C., 0.96 m / min. The film was developed under the conditions and baked at 235 ° C. for 5 minutes using the following baking gum solution. Thereafter, printing was performed with a Heidel KOR-D machine, and whether or not normal printed matter was printed was observed every 10,000 sheets, and the number of sheets was evaluated.
The above evaluation results are also shown in Table 6.

The numbers indicating the types of specific alkali-soluble resins in Table 6 correspond to the compound numbers of the specific examples listed above in Table 5.
The details of “Resin A” used in Comparative Examples 1 and 5 and “Resin B” used in Comparative Example 3 are as follows.
Resin A: m / p cresol noborazo resin (m / p ratio = 6/4, Mw: 5000)
Resin B: N- (4-aminosulfonylphenyl) methacrylamide
/ Acrylonitrile / Methyl methacrylate
(Molar ratio 36:34:30, weight average molecular weight 50,000)

As shown in Table 6, the lithographic printing plates of Examples 1 to 9 obtained by the method of the present invention are excellent in burning printing resistance and cleaner resistance, and also have good dot image reproducibility. Results were obtained.
On the other hand, in place of the specific alkali-soluble resin used in the present invention, the lithographic printing plates of Comparative Examples 1 and 5 using a resin A that is a conventionally known alkali-soluble resin have burning printing resistance, cleaner resistance, and Good results were not obtained for all halftone dot image reproducibility. Further, the lithographic printing plate of Comparative Example 3 using the resin B was able to obtain cleaner resistance, but did not obtain good results with respect to burning printing durability and halftone image reproducibility.
Also, the specific alkali-soluble resin used in the present invention is out of the range of the dry cooling condition of the present invention (the temperature condition of 150 ° C. or higher and 250 ° C. or lower is maintained for 0.1 second or longer and 60 seconds or shorter). In Comparative Example 2, Comparative Example 4 and Comparative Example 6, although cleaner resistance was obtained, good results were not obtained in burning printing durability and halftone image reproducibility.

It is a schematic sectional drawing which shows one aspect | mode of the drying apparatus which can be used for drying after recording layer application | coating applicable to this invention.

Claims (2)

On the support, there is a recording layer containing an alkali-soluble resin containing a monomer unit having a phenyl group substituted by a substituent represented by the following general formula (1), and an infrared absorber. In addition, the drying step of drying the recording layer after coating the recording layer includes a heat treatment for maintaining a temperature condition of 150 ° C. or more and 250 ° C. or less for 0.1 seconds or more and 60 seconds or less. A method for producing a lithographic printing plate.

[In the general formula (1), Z ¹ , Z ² and Z ³ each independently represents a monovalent substituent consisting of a hydrogen atom or a nonmetallic atom. ]   The drying step includes a cooling process in which, after the heat treatment, cooling is performed at an average cooling rate in the range of 5 ° C./second to 30 ° C./second until the temperature of the recording layer reaches 40 ° C. The method for producing a lithographic printing plate according to claim 1.

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