JP5484285B2 - Infrared photosensitive positive lithographic printing plate precursor and method for producing the same, and lithographic printing plate and method for producing the same - Google Patents

Description

  The present invention relates to an infrared-sensitive positive lithographic printing plate precursor and a production method thereof, and a lithographic printing plate and a production method thereof.

  Conventionally, various photosensitive compositions have been used as visible image forming and lithographic printing plate materials. In particular, the development of lasers in lithographic printing in recent years has been remarkable, and in particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can be easily obtained in high output and small size. These lasers are very useful as an exposure light source when making a plate directly from data.

  The infrared-sensitive positive lithographic printing plate precursor comprises an alkali-soluble binder resin, an infrared absorber that absorbs light and generates heat, and the like as essential components. This infrared absorber or the like acts as a development inhibitor that substantially lowers the solubility of the binder resin in the developer by interaction with the binder resin in the unexposed area (image area), and the exposed area (non-image area). Then, the interaction between the infrared absorbent and the binder resin is weakened by the generated heat and is dissolved in an alkali developer to form a lithographic printing plate. However, such an infrared-sensitive positive lithographic printing plate precursor has low processability with a fatigue developer having a decreased activity, and the development latitude is not sufficient.

  In order to solve such a development latitude problem, it is necessary to use a recording layer that can develop a non-image area more easily, that is, a recording layer made of a material having better solubility in an alkaline aqueous solution. Conceivable. However, such a recording layer is chemically weak in the image area, and is easily damaged by a developer, an ink washing solvent used during printing, a plate cleaner, and the like. There was a problem of poor chemical resistance. In order to solve such a problem, a method of layering recording layers is known (see, for example, Patent Document 1).

  However, the difference between the solubility resistance of the unexposed area (image area) with respect to the developer and the solubility of the exposed area (non-image area) only under the method of layering the recording layer ( Discrimination; hereinafter also referred to as “dissolving discriminating” or “dissolving discriminability”) is not yet sufficient, and there is a problem that overdevelopment and development defects are likely to occur due to fluctuations in use conditions. A material with an excellent latitude was eagerly desired.

  In a lithographic printing plate precursor having a recording layer having a multilayer structure, it has been proposed to use a polyurethane resin having a substituent having an acidic hydrogen atom in the upper layer as a technique for improving development latitude and durability in an image area. (For example, refer to Patent Document 2). However, it has not been sufficient yet, and further improvement of the infrared-sensitive positive lithographic printing plate precursor has been awaited.

  On the other hand, in order to improve the coating property of the recording layer in the lithographic printing plate precursor and to improve the hydrophobicity of the image area, a technique for containing a fluorine-based polymer compound in the composition constituting the recording layer has been proposed ( (For example, see Patent Document 3.)

JP 11-218914 A JP 2007-17913 A Japanese Patent No. 3856298

  An object of the present invention is to provide an infrared-sensitive positive lithographic printing plate precursor having a wide development latitude and excellent in printing durability, a method for producing the same, and a lithographic printing plate having excellent printing durability and The manufacturing method is provided.

Means for solving the above problems are as follows.
<1> A recording layer provided by forming a lower layer and an upper layer in this order on a support having a hydrophilic surface, and the lower layer is a water-insoluble and soluble or dispersible resin in an alkaline aqueous solution. A fluoroaliphatic group-containing copolymer of 5% by mass to 50% by mass with respect to the total solid content of the lower layer, wherein the upper layer is water-insoluble and soluble or dispersed in an alkaline aqueous solution. Infrared photosensitive positive planographic printing plate precursor, which is a layer containing a conductive polyurethane resin.
<2> The infrared ray according to <1>, wherein the fluoroaliphatic group-containing copolymer is a copolymer containing 5 mol% to 95 mol% of a monomer unit containing a fluoroaliphatic group in all monomer units. Photosensitive positive planographic printing plate precursor.
<3> The infrared-sensitive positive lithographic printing plate precursor as described in <1> or <2>, wherein the fluoroaliphatic group-containing copolymer is a copolymer containing a monomer unit having an acidic group in a side chain.
<4> The infrared-sensitive positive lithographic printing plate precursor as described in <3>, wherein the acidic group in the monomer unit having an acidic group in the side chain is a phenolic hydroxyl group, a sulfonamide group, or an imide group.
<5> The infrared-sensitive positive lithographic printing plate precursor as described in any one of <1> to <4>, wherein at least one of the lower layer and the upper layer contains an infrared absorber.
<6> A coating solution containing a resin in which the lower layer is water-insoluble and soluble or dispersible in an aqueous alkali solution, the fluoroaliphatic group-containing copolymer, and a solvent is applied onto the support and dried. The infrared-sensitive positive lithographic printing plate precursor as described in any one of <1> to <5>, which is a layer formed by
<7> The method for producing an infrared-sensitive positive lithographic printing plate precursor according to any one of <1> to <6>, wherein the lower layer forming coating solution and the upper layer forming coating solution are placed on the support in this order. A method for producing an infrared-sensitive positive lithographic printing plate precursor comprising a step of coating by sequential coating.
<8> An exposure step of exposing the infrared-sensitive positive lithographic printing plate precursor according to any one of <1> to <6> imagewise with infrared rays, and the positive lithographic printing plate precursor after exposure A lithographic printing plate comprising a development step in which the aqueous solution is developed using an aqueous alkali solution in this order.
<9> A lithographic printing plate obtained by the method for producing a lithographic printing plate according to <8>.

  According to the present invention, an infrared-sensitive positive lithographic printing plate precursor having a wide development latitude and excellent in printing durability, a method for producing the same, and a lithographic printing plate having excellent printing durability and A manufacturing method thereof can be provided.

[Infrared photosensitive lithographic printing plate precursor]
The infrared-sensitive lithographic printing plate precursor (hereinafter referred to as “lithographic printing plate precursor” as appropriate) of the present invention is a recording layer provided by forming a lower layer and an upper layer in this order on a support having a hydrophilic surface. The lower layer is a water-insoluble and soluble or dispersible resin in an alkaline aqueous solution, and a fluoroaliphatic group-containing copolymer of 5% by mass to 50% by mass with respect to the total solid content of the lower layer. The upper layer is a layer containing a polyurethane resin that is water-insoluble, water-insoluble, and soluble or dispersible in an alkaline aqueous solution.
The lithographic printing plate precursor according to the invention may further have other layers provided as desired, such as an undercoat layer and a backcoat layer.
Since the lithographic printing plate precursor according to the invention has the above-described configuration, the lithographic printing plate obtained from the lithographic printing plate precursor is excellent in development latitude and excellent in printing durability.

In the lithographic printing plate precursor according to the present invention, one of the characteristic constituent elements that contribute to excellent development latitude and printing durability is that the lower layer in the recording layer is 5% by mass relative to the total solid content of the lower layer. It is containing -50 mass% fluoro aliphatic group containing copolymer.
The mechanism of action is not yet clear, but is presumed as follows.
That is, in the present invention, the fluoroaliphatic group-containing copolymer contained in a specific amount in the lower layer has low solubility in a solvent and can be unevenly distributed near the interface with the upper layer in the lower layer. For this reason, when the recording layer is formed, mixing of the lower layer forming coating liquid and the upper layer forming coating liquid is suppressed, and intermixing of the formed lower layer and upper layer is suppressed. In addition, since the suppression of interlayer mixing in the lower layer and the upper layer constituting the recording layer having a multilayer structure can fully exhibit the functions required for the recording layer, the lithographic printing plate precursor according to the invention is dissolved during development. Discreet and easy to develop, wide development latitude. Furthermore, when the obtained lithographic printing plate is used for printing, even if the solvent contained in the ink applied to the image area permeates the upper layer and penetrates in the direction of the support, Since the fluoroaliphatic group-containing copolymer is present near the interface with the upper layer, the penetration of the solvent into the lower layer is suppressed, so that the recording layer is prevented from peeling off from the support, and the printing durability is also improved. improves.

  The lithographic printing plate precursor of the present invention is a lithographic printing plate precursor that is widely sensitized to infrared rays, is particularly suitable for infrared laser exposure, and gives a positive image.

(Recording layer)
The recording layer in the lithographic printing plate precursor according to the invention is a recording layer having a multilayer structure in which a lower layer and an upper layer are formed in this order on a support having a hydrophilic surface.

<Lower layer>
The lower layer in the lithographic printing plate precursor according to the present invention is a layer provided on the support side among the layers constituting the recording layer having a multilayer structure, an insoluble and soluble or dispersible resin in an alkaline aqueous solution, and the entire solid of the lower layer. 5% by mass to 50% by mass of a fluoroaliphatic group-containing copolymer is contained with respect to the content. An upper layer described later is provided on the lower layer.
Hereinafter, each component contained in the lower layer will be described.

<< Fluoroaliphatic group-containing copolymer >>
A lower layer contains 5 mass%-50 mass% of fluoro aliphatic group containing copolymer with respect to the mass of the total solid of this lower layer.
Here, the “total solid content of the lower layer” means all components excluding the solvent among the components contained in the lower layer.

  The content of the fluoroaliphatic group-containing copolymer in the lower layer is 5% by mass to 50% by mass, more preferably 10% by mass to 40% by mass, and more preferably 10% by mass to 40% by mass based on the total solid content of the lower layer. Preferably it is 20 mass%-40 mass%. When the content of the fluoroaliphatic group-containing copolymer is less than 5% by mass with respect to the total solid content of the lower layer, the development latitude is insufficiently improved, and when it exceeds 50% by mass, the resulting lithographic plate is obtained. The printing durability of the printing plate decreases.

  The fluoroaliphatic group-containing copolymer is a copolymer containing a monomer unit containing a fluoroaliphatic group and another monomer unit different from this.

  The monomer unit containing a fluoroaliphatic group is preferably contained in a molar ratio of 5 mol% to 95 mol% in all monomer units contained in the fluoroaliphatic group-containing copolymer, and 10 mol% to 80 mol. %, More preferably 10 mol% to 60 mol%.

  In the fluoroaliphatic group-containing copolymer, each of the monomer unit containing the fluoroaliphatic group and the other monomer unit may be contained alone or in combination of two or more.

In the fluoroaliphatic group-containing copolymer, the “fluoroaliphatic group” means an aliphatic group in which part or all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms.
Examples of fluoroaliphatic groups include linear, branched, or cyclic alkyl groups, alkenyl groups, etc., in which some or all of the hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms.
As the fluoroaliphatic group, those in which all of hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms are particularly preferable.

  As a weight average molecular weight (Mw) of a fluoro aliphatic group containing copolymer, the range of 2,000-100,000 is preferable from a viewpoint of developability and printing durability.

  In addition, the weight average molecular weight in this specification is a polystyrene equivalent weight average molecular weight by gel permeation chromatography (GPC).

  One of the suitable aspects of the monomer which comprises the monomer unit containing a fluoro aliphatic group is a monomer represented by the following general formula (a).

In general formula (a), R ¹ represents a hydrogen atom or a methyl group, X represents an oxygen atom, a sulfur atom, or —N (R ² ) —, m represents an integer of 1 to 6, and Rf represents Represents a fluoroalkyl group. R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

In general formula (a), examples of the alkyl moiety in Rf include an alkyl moiety having 1 to 12 carbon atoms (more preferably 2 to 10, more preferably 4 to 8).
The alkyl moiety in Rf may be linear, branched or cyclic, and more preferably linear or branched.
Rf may be a fluoroalkyl group in which a part of hydrogen atoms bonded to the carbon atoms constituting the part is substituted with fluorine atoms, or all the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms. Or a perfluoroalkyl group. Rf is preferably a perfluoroalkyl group.

R ¹ represents a hydrogen atom or a methyl group.

R ₂ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (a methyl group, an ethyl group, a propyl group, or a butyl group), and more preferably a hydrogen atom.

X represents an oxygen atom, a sulfur atom, or —N (R ² ) —, and more preferably an oxygen atom or —N (R ² ) —.

m represents an integer of 1 to 6, more preferably 2 to 4.
The alkylene group linking X and Rf may further have a substituent, and examples of the substituent include a hydroxy group.

  Hereinafter, although the specific example of the monomer which can comprise the monomer unit containing a fluoro aliphatic group is given, this invention is not limited to these.

In the fluoroaliphatic group-containing copolymer, the monomer that can form another monomer unit is preferably a monomer unit having an acidic group (functional group containing an acidic hydrogen atom) from the viewpoint of developability.
The monomer unit having an acidic group is preferably a monomer unit having a functional group such as a phenolic hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a phosphonic acid group, a sulfonamide group, or an active imide group.
Examples of the monomer for forming the monomer unit having an acidic group include an ethylenically unsaturated monomer having an acidic group. Preferred examples of the ethylenically unsaturated monomer having an acidic group include acrylic acid, methacrylic acid, and a polymerizable monomer represented by the following formula, and these monomers may be used as a mixture. In the following formula, R ⁴ represents a hydrogen atom or a methyl group.

  Among these, as other monomer units, from the viewpoint of printing durability, a monomer unit having a sulfonamide group, an active imide group, or a phenolic hydroxyl group is preferable, and a monomer unit having a sulfonamide group is particularly preferable.

Furthermore, in the fluoroaliphatic group-containing copolymer, examples of the other polymerizable monomer that can constitute another monomer unit include the following compounds.
Alkyl acrylates and alkyl methacrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate.
Acrylic acid esters and methacrylic acid esters having a hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
Acrylamide or methacrylamide such as acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-phenylacrylamide, etc.
Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate. Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene.
Other nitrogen atom-containing monomers such as N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile and methacrylonitrile.
Among these other polymerizable monomers, (meth) acrylic acid esters, (meth) acrylamides, and (meth) acrylonitrile are preferably used.

  In the present specification, “(meth) acryl” is an expression including both “acryl” and “methacryl”.

  Commercially available products may be used as the fluoroaliphatic group-containing copolymer, and examples thereof include a fluorinated surfactant Megafac series manufactured by DIC Corporation.

  Hereinafter, although the specific example (polymers 1-16 shown below) of a fluoro aliphatic group containing copolymer is given, this invention is not limited to these. In addition, the copolymerization ratio in the polymers 1-16 is a molar ratio.

Hereinafter, examples of the synthesis of the fluoroaliphatic group-containing copolymer will be described using the polymer 6 as an example.
(Synthesis Example 1: Synthesis of Polymer 6)
In a 200 mL three-necked flask, 4.83 g of N- (4-sulfamoylphenyl) methacrylamide and 28.39 g of N, N-dimethylacetamide (DMAc: manufactured by Wako Pure Chemical Industries, Ltd.) were weighed and placed under a nitrogen atmosphere. Stir at 1 ° C. for 1 hour. Under stirring at 70 ° C., DMAc 83.50 g, N- (4-sulfamoylphenyl) methacrylamide 19.32 g, hexafluoroisopropyl methacrylate (Daikin Kogyo) 11.57 g, acrylonitrile (Tokyo Chemical Industry) ) A solution of 5.33 g and V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) 0.58 g was added dropwise over 2 hours. After completion of the dropwise addition, the reaction solution was heated to 90 ° C., 0.58 g of V-601 (manufactured by Wako Pure Chemical Industries) was added, and the mixture was further heated and stirred for 2 hours. The obtained reaction liquid was cooled to room temperature, and then poured into 5 L of water, and the white powder obtained was collected by filtration to obtain polymer 6. It was confirmed by GPC, NMR and IR that the obtained white powder was polymer 6.

  Other fluoroaliphatic group-containing copolymers such as polymers 1 to 16 can also be synthesized in the same manner as polymer 6 except that the raw material monomer used is changed.

<< Water-insoluble and soluble or dispersible resin in alkaline solution >>
The lower layer contains a water-insoluble resin that is soluble or dispersible in an aqueous alkali solution (hereinafter, abbreviated as “alkali-soluble resin” as appropriate).
Here, a water-insoluble and soluble or dispersible resin in an alkaline aqueous solution contained in the lower layer is “water-insoluble” when the solubility of the resin in water at room temperature (25 ° C.) is 1% by mass or less. (More preferably, 0.1% by mass or less), and “soluble in an alkaline aqueous solution” means that the resin is processed in an alkaline aqueous solution having a pH of 8.5 to 13.5 at a standard development time. This means that the resin is dispersible in an alkaline aqueous solution, and the resin is in a state generally referred to as an emulsion or colloidal dispersion in an alkaline aqueous solution having a pH of 8.5 to 13.5. It means to present.

  The alkali-soluble resin that can be used in the lower layer of the present invention is not particularly limited as long as it has a property of dissolving or dispersing when contacted with an alkaline developer. The alkali-soluble resin is preferably a homopolymer containing an acidic group in the main chain and / or side chain in the polymer, a copolymer thereof, or a mixture thereof.

The alkali-soluble resin having an acidic group preferably has a functional group such as a phenolic hydroxyl group, a carboxy group, a sulfonic acid group, a phosphoric acid group, a sulfonamide group, or an active imide group. The alkali-soluble resin can be suitably produced by copolymerizing a monomer mixture containing one or more ethylenically unsaturated monomers having an acidic group. Preferred examples of the ethylenically unsaturated monomer having an acidic group include acrylic acid, methacrylic acid, and a polymerizable monomer represented by the following formula, and these monomers may be used as a mixture. In the following formula, R ⁴ represents a hydrogen atom or a methyl group.

  The alkali-soluble resin that can be used for the lower layer is preferably a polymer compound obtained by copolymerizing another polymerizable monomer in addition to the above polymerizable monomer. In this case, the copolymerization ratio is 10 mol of a monomer that imparts alkali solubility such as a monomer having an acidic group such as a phenolic hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a sulfonamide group, or an active imide group. %, Preferably 20 mol% or more. When the copolymerization component of the monomer that imparts alkali solubility is 10 mol% or more, sufficient alkali solubility is obtained and the developability is excellent.

Examples of other polymerizable monomers that can be used in the alkali-soluble resin include the following compounds.
Alkyl acrylates and alkyl methacrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. Acrylic acid esters and methacrylic acid esters having a hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate. Acrylamide or methacrylamide such as acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-phenylacrylamide, etc. Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate. Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene. Other nitrogen atom-containing monomers such as N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile and methacrylonitrile. N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-2-methylphenylmaleimide, N-2,6-diethylphenylmaleimide, N-2-chlorophenylmaleimide, Maleimides such as N-cyclohexylmaleimide, N-laurylmaleimide, N-hydroxyphenylmaleimide and the like.
Among these other polymerizable monomers, (meth) acrylic acid esters, (meth) acrylamides, maleimides, and (meth) acrylonitrile are preferably used.

Moreover, as an alkali-soluble resin, a novolak resin is mentioned preferably.
Examples of the novolak resin that can be used in the present invention include phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (m-, p-, or m). Any of-/ p-mixing may be used.) Novolak resins such as mixed formaldehyde resins and pyrogallol acetone resins are preferred.
Furthermore, as described in U.S. Pat. No. 4,123,279, a phenol having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin; Examples thereof include condensation polymers with formaldehyde. Moreover, it is preferable that the weight average molecular weight (Mw) is 500 or more, and it is more preferable that it is 1,000-700,000. Moreover, it is preferable that the number average molecular weight (Mn) is 500 or more, and it is more preferable that it is 750-650,000. The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  The alkali-soluble resin preferably has a weight average molecular weight of 2,000 or more and a number average molecular weight of 500 or more, a weight average molecular weight of 5,000 to 300,000 and a number average molecular weight of 800 to 250,000. It is more preferable that Moreover, it is preferable that the dispersity (weight average molecular weight / number average molecular weight) of the alkali-soluble resin is 1.1 to 10.

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

  It is preferable that content of alkali-soluble resin with respect to the total solid of a lower layer is 50 mass%-98 mass%. When the content of the alkali-soluble resin in the lower layer is 50% by mass or more, the recording layer (photosensitive layer) is more excellent in durability, and when it is 98% by mass or less, both sensitivity and durability are further improved.

<< Infrared absorber >>
The lithographic printing plate precursor according to the invention preferably contains an infrared absorber in the lower layer.
The infrared absorber is not particularly limited as long as it is a dye or pigment that absorbs infrared rays and generates heat, and pigments can be used as various dyes known as infrared absorbers.

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

  Examples of the dye that absorbs at least infrared rays or near infrared rays include, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Cyanine dyes described in each publication, methine dyes described in JP-A Nos. 58-173696, 58-181690, 58-194595, etc. No. 112793, JP 58-224793, JP 59-48187, JP 59-73996, JP 60-52940, JP 60-63744, etc. Naphthoquinone dyes, squarylium dyes described in JP-A-58-112792, etc., cyanine dyes described in British Patent 434,875, etc. Can.

As the dye, a near-infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and substituted dyes described in US Pat. No. 3,881,924 are also used. Arylbenzo (thio) pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, and 58-220143 59-41363, 59-84248, 59-84249, 59-146063, 59-146061, and pyrylium compounds described in JP-A-59-216146. The cyanine dyes described above, the pentamethine thiopyrylium salt described in U.S. Pat. No. 4,283,475, and the like, and JP-B Nos. Pyrylium compounds disclosed in JP etc. As commercially available products, Epolight III-178 of Eporin Co., Epolight III-130, Epolight III-125 and the like are particularly preferably used.
Further, another particularly preferable example of the dye includes near infrared absorbing dyes described as formulas (I) and (II) in US Pat. No. 4,756,993.

  A particularly preferred dye as the infrared absorber is cyanine dye A shown below.

  In addition, as pigments as infrared absorbers, commercially available pigments and color index (CI) manuals, “Latest Pigment Handbook” (edited by the Japan Pigment Technology Association, published in 1977), “Latest Pigment Applied Technology” (CMC Publishing) 1986), “Printing Ink Technology” CMC Publishing, 1984) can be used.

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

  As long as the dispersibility in the composition is stable, carbon black can be used regardless of the classification according to ASTM or the use (for example, for color, for rubber, for dry battery, etc.). Carbon black includes, for example, furnace black, thermal black, channel black, lamp black, acetylene black and the like. In order to facilitate dispersion, black colorants such as carbon black can be used as color chips or color pastes previously dispersed in nitrocellulose or a binder, if necessary. Such chips and pastes can be easily obtained as commercial products.

  In the present invention, it is also possible to use carbon black having a relatively low specific surface area and relatively low DBP absorption and even finer carbon black having a large specific surface area. Examples of suitable carbon blacks include Printex® U, Printex® A, or Specialschwarz® 4 (from Degussa).

  The addition amount of the infrared absorber in the lower layer is preferably 0.01% by mass to 50% by mass with respect to the total solid content of the lower layer, from the viewpoint of sensitivity, layer uniformity and durability, and 0.1% by mass. % To 30% by mass is more preferable, and 1.0% to 30% by mass is particularly preferable.

<Upper layer>
The upper layer in the lithographic printing plate precursor according to the invention is a layer provided on the side opposite to the support side of the lower layer among the layers constituting the recording layer having a multilayer structure.

<< Water-insoluble and soluble or dispersible polyurethane resin in alkaline solution >>
The upper layer contains a polyurethane resin that is insoluble and soluble or dispersible in an alkaline aqueous solution (hereinafter abbreviated as “specific polyurethane” as appropriate).

  The specific polyurethane resin contained in the upper layer is “water-insoluble” when the solubility of the resin in water at room temperature (25 ° C.) is 1% by mass or less (more preferably 0.1% by mass or less). “Solubility in alkaline aqueous solution” means that the resin is soluble in an alkaline aqueous solution having a pH of 8.5 to 13.5 by processing for a standard development time. "Dispersible in" means that the resin exhibits a state generally referred to as an emulsion or colloidal dispersion in an alkaline aqueous solution having a pH of 8.5 to 13.5.

  One preferred embodiment of the specific polyurethane includes a polyurethane resin having a substituent containing an acidic hydrogen atom.

  Moreover, as another suitable aspect of specific polyurethane resin, the polyurethane resin which the solubility to alkaline aqueous solution improves with a heat | fever is mentioned.

<< Polyurethane resin having a substituent containing an acidic hydrogen atom >>
A polyurethane resin having a substituent containing an acidic hydrogen atom (hereinafter referred to as “specific polyurethane (1)” as appropriate) will be described.
In the specific polyurethane (1), the acidic hydrogen atom is a carboxyl group, —SO ₂ NH ₂ group, —SO ₂ NHCOO— group, —CONHSO ₂ — group, —CONHSO ₂ NH— group, —NHCONHSO ₂ — group, etc. It is a hydrogen atom contained in an acidic functional group, and particularly preferably a hydrogen atom contained in a carboxyl group.

  The specific polyurethane (1) is, for example, a method of reacting a diol having a carboxy group with another diol if necessary and a diisocyanate; a diol, a diisocyanate having a carboxy group, and if necessary A method of reacting with another diisocyanate; or reacting a diol having a carboxy group, if necessary, another diol, a diisocyanate having a carboxy group, and another diisocyanate if necessary Can be synthesized by the method of

  Examples of the diol having a carboxy group include 3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxyethyl) propionic acid, and 2,2-bis (3-hydroxypropyl). Examples include propionic acid, 2,2-bis (hydroxymethyl) acetic acid, bis- (4-hydroxyphenyl) acetic acid, 4,4-bis- (4-hydroxyphenyl) pentanoic acid, tartaric acid, 2-bis (hydroxymethyl) propionic acid is more preferable in terms of reactivity with isocyanate.

  Other diols include dimethylolpropane, polypropylene glycol, neopentyl glycol, 1,3-propanediol, polytetramethylene ether glycol, polyester polyol, polymer polyol, polycaprolactone polyol, polycarbonate diol, 1,4-butanediol, Examples include 1,5-pentadiol, 1,6-hexanediol, polybutadiene polyol, and the like.

  Examples of the diisocyanate having a carboxy group include dimer acid diisocyanate.

  Other diisocyanates include 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, naphthylene-1,5-diisocyanate, tetramethylxylene diisocyanate, hexamethylene diisocyanate, toluene-2. , 4-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate and the like.

  The molar ratio of diisocyanate and diol is preferably 0.7: 1 to 1.5: 1. When an isocyanate group remains at the end of the polymer, the isocyanate group is finally treated by treatment with alcohols or amines. It is synthesized in a form that does not remain.

  The specific polyurethane (1) preferably has a weight average molecular weight in the range of 2,000 to 100,000 from the viewpoints of sensitivity and printing durability.

<< Polyurethane resin whose solubility in aqueous alkali solution is improved by heat >>
A polyurethane resin (hereinafter referred to as “specific polyurethane (2)” as appropriate) whose solubility in an alkaline aqueous solution is improved by heat will be described.
In general, polymers capable of forming highly durable coatings tend to have low developer permeability, are susceptible to developer activity, and have insufficient development latitude. Strength, durability, and development latitude are in a trade-off relationship.
On the other hand, since the specific polyurethane (2) has a property that the solubility in an alkaline aqueous solution is improved by heat, it has a high film strength derived from polyurethane in the unexposed area, and the polyurethane of the exposed area is heated by heat. Since the solubility in an aqueous alkali solution is improved, the aqueous solution is quickly removed by a developer which is an aqueous alkali solution.
In the specific polyurethane (2), there is no particular limitation on the means for imparting the “characteristic that the solubility in an alkaline aqueous solution is improved by heat”, but in the present invention, the exposure area is changed from hydrophobic to hydrophilic by heat. Polyurethane having a group for polarity conversion in the side chain can be used. The functional group capable of causing such polarity conversion may be a functional group that undergoes polarity conversion from hydrophobicity to hydrophilicity by heat, and from an acid generator optionally contained in the composition constituting the upper layer. It may be a functional group that converts polarity from hydrophobic to hydrophilic by the generated acid, or may be a functional group that converts polarity from hydrophobic to hydrophilic by both heat and acid. Hereinafter, such a functional group is appropriately referred to as a heat / acid polarity conversion group.

  Examples of the group that converts polarity from hydrophobic to hydrophilic by at least one of heat and acid include, for example, tertiary ester groups described in paragraphs [0053] to [0090] of JP-A-2002-309057, A group having a lactone skeleton, a benzyl ester group described in JP-A-60-3625, JP-A-63-010153, JP-A-9-171254, JP-A-10-55067, JP-A-10-111564, No. 10-87733, No. 10-153853, No. 10-228102, No. 10-268507, No. 282648, No. 10-282670, etc., or European Patent Publication No. EP-08454747A1 Acetal group, ketal group and orthocarboxylic acid ester group described in Japanese Patent Application Laid-Open No. 62-2517 No. 3, carbonic acid ester groups described in JP-A-62-209451, ortho-carbonic acid ester groups described in JP-A-62-209451, JP-A-48-89603, JP-A-512072014, JP-A-53-133429, Examples thereof include groups having a C—O—C bond described in JP-A-55-12995, JP-A-55-126236, and JP-A-56-17345. Further, a silyl ester group described in JP-A-60-10247, an orthosilicate group described in JP-A-62-280842, JP-A-60-37549, and 60- Examples thereof include a group having a Si—O—C bond described in each publication of No. 121446 and a group having a Si—N bond described in JP-A-62-2222246. Further, a sulfonate group described in JP-A-10-282644, an orthotitanate group described in JP-A-62-280841, and a C- group described in JP-A-62-244038. A group having an S bond can be used.

Among these groups, from the viewpoint of sensitivity and printing durability, a tertiary ester group, a group having a lactone skeleton, a benzyl ester group, an acetal group, a ketal group, an orthocarboxylic ester group, a carbonate ester group, an ortho carbonate ester Group, silyl ester group, and sulfonic acid ester group are preferable, and from the viewpoint of storage stability and production suitability, a tertiary ester group, a group having a lactone skeleton, an acetal group, a ketal group, and a carbonate ester group are preferable. .
A functional group capable of decomposing by heat / acid to generate an acid is preferred as the group that converts polarity from hydrophobic to hydrophilic by at least one of the heat and acid (hereinafter referred to as “heat / acid”).
The group that converts the polarity from hydrophobic to hydrophilic by heat / acid, and the thermally decomposable group, which is a preferred embodiment thereof, is a side chain of polyurethane from the viewpoint of controlling the ease of production and the amount of the thermally decomposable group introduced. It is preferable to be introduced into

Here, the acid group is a group having a pKa of 13 or less, and the pKa is preferably from -3 to 12, and more preferably from 0 to 11, from the viewpoint of developability and printing durability.
The acid group generated by the decomposition of the thermally decomposable group is preferably a carboxylic acid group, a phenolic hydroxyl group, or a sulfonic acid group, and more preferably a carboxylic acid group or a phenolic hydroxyl group.
The group capable of generating an acid group by being decomposed by heat that can be applied to the present invention is not limited as long as it is a group that can be decomposed by heat generated by infrared laser exposure to generate an acid group. A group in which an acid group such as a group, a phenolic hydroxyl group, or a sulfonic acid group is protected with a protecting group can be preferably used.

  Examples of the carboxylic acid group having a protective group, which is a thermally decomposable group that decomposes into a carboxylic acid group, include groups represented by the following general formula (I) to general formula (IV) that are image-forming and resistant. Preferred from the viewpoint of printability.

In general formula (I), R ^{1 to} R ³ each independently represents a monovalent hydrocarbon group.
In general formula (II), R ^{4 to} R ⁶ each independently represent a hydrogen atom or a monovalent hydrocarbon group.
In general formula (III), R < ⁷ > -R < ¹¹ > represents a hydrogen atom or a monovalent hydrocarbon group each independently.
In general formula (IV), R < ¹² > -R < ¹⁴ > represents a monovalent hydrocarbon group each independently.
The group represented by R ^{1 to} R ¹⁴ may further have a substituent. R ¹ and R ² , R ⁴ and R ⁶ , R ⁹ and R ¹¹ may be bonded to each other to form a ring structure.

In the general formulas (I) to (IV), examples of the monovalent hydrocarbon group include an alkyl group, an aryl group, an alkenyl group, an alkynyl group, an aralkyl group, and the like, and an alkyl group, an alkenyl group, and an aralkyl group. Among them, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, and the like are preferable from the viewpoints of printing durability and sensitivity.
These monovalent hydrocarbon groups may have a substituent, and examples of the substituent that can be introduced include a halogen atom, an ether group, a thioether group, an ester group, a urethane group, and a urea group.
As R < ¹ > -R < ³ >, Preferably, a methyl group, an ethyl group, a propyl group, a butyl group, a chloromethyl group, a bromomethyl group, and iodomethyl are mentioned each independently.
R ^{4 to} R ⁶ are preferably each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, a cyclohexyl group, or a tetrahydrofuran group. Nyl group, tetrahydropyranyl group, methoxyethyl group and the like can be mentioned.
R ^{7 to} R ¹¹ are preferably each independently a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or a phenyl group (as a ring structure formed by bonding R ⁹ and R ¹¹ to each other). Phenyl group) and the like.
As R < ¹² > -R < ¹⁴ >, Preferably, a methyl group, an ethyl group, n-propyl group, n-butyl group, iso-butyl group, tert-butyl group etc. are mentioned each independently.

  As the phenolic hydroxyl group having a protecting group, which is a thermally decomposable group that decomposes to become a phenolic hydroxyl group, groups represented by the following general formulas (V) to (VII) have image-forming properties and printing durability. It is preferable from the viewpoint.

In the general formula ^(V), R 4 ~R ⁶ are each the same meaning as ^R 4 to R ⁶ in Formula (II), preferred examples are also the same.
In the general formula (VI), R ¹⁵ represents a monovalent hydrocarbon group.
Specific examples of R ¹⁵ include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, and a phenyl group, preferably a methyl group, a phenyl group, and the like. It is a group.
In General Formula (VII), A represents O, S, or —N (R ¹⁷ ) —, and R ¹⁶ represents a monovalent hydrocarbon group. Here, R ¹⁷ represents a hydrogen atom or a monovalent hydrocarbon group, preferably a methyl group, an ethyl group, or a phenyl group. A is preferably O, and R ¹⁶ is preferably a methyl group, an ethyl group, a propyl group, a tert-butyl group, an allyl group, or the like. R ¹⁷ is preferably a methyl group.
The groups represented by R ^{15 to} R ¹⁷ may further have a substituent.
Examples of the sulfonic acid group having a protecting group that is decomposed by heat to become a sulfonic acid group include a sulfonic acid ester group represented by the following general formula (VIII), or a sulfonic acid described in JP-A-10-282644 Esters are preferred from the viewpoints of image formation and printing durability.

In the general formula (VIII), R ¹⁸ represents a monovalent hydrocarbon group which may have a substituent.
In the general formula (VIII), examples of the monovalent hydrocarbon group include an alkyl group, an aryl group, a cycloalkyl group, an alkenyl group, an aralkyl group, and the like, and an alkyl group, a cycloalkyl group, and an aralkyl group are preferable. Of these, an alkyl group having 2 to 6 carbon atoms, a cycloalkyl group having 4 to 10 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, and the like are preferable from the viewpoints of sensitivity and printing durability.
Examples of the substituent that can be introduced into R ¹⁸ include a halogen atom, an ether group, a thioether group, an ester group, a urethane group, and a urea group. R ¹⁶ is preferably a cyclohexyl group or a benzyl group.
One of these thermally decomposable groups that the specific polyurethane (2) has in the side chain may be introduced into the polymer, or two or more thereof may be introduced. A plurality of types of polyurethanes having different thermally decomposable groups may be mixed and used.

  The functional group that decomposes by heat to generate an acid group is, for example, at least one selected from the group consisting of functional groups represented by the following general formulas (2) to (4). preferable.

In general formula (2), R ¹ represents a functional group that forms a tertiary ester by bonding to an adjacent oxygen atom, or a functional group that forms a hemiacetal by combining with an adjacent oxygen atom.
In the general formula (3), R ^S represents a functional group that forms a silyl ester group by bonding to an adjacent oxygen atom.
In General Formula (4), R ² represents a functional group that forms a secondary ester by bonding to an adjacent oxygen atom, or a functional group that forms a tertiary ester by combining with an adjacent oxygen atom.
Here, as a functional group which forms a tertiary ester by bonding with an adjacent oxygen atom, tert-butyl ester, 1,1-dimethyl-2-chloroethyl ester, 1,1-dimethylethyl ester, 1-methyl Examples thereof include cyclohexyl ester, and tert-butyl ester is preferable. Moreover, as a functional group which combines with an adjacent oxygen atom and constitutes a hemiacetal structure, 1-ethoxyethyl ester, 1-butoxyethyl ester, 1-methoxyethoxyethyl ester, tetrahydro-2H-pyran-2-yl ester , Tetrahydrofuran-2-yl ester and the like, and 1-ethoxyethyl ester, 1-butoxyethyl ester, and tetrahydrofuran-2-yl ester are preferable.
As the silyl ester group represented by ^RS , for example, trimethylsilyl ester is preferable.
Examples of the functional group that forms a secondary ester by bonding to an adjacent oxygen atom include a cyclohexyl group, an iso-propyl group, an iso-butyl group, and the like, and among them, a cyclohexyl group is preferable. Further, the functional group constituting the tertiary ester bonded to the adjacent oxygen atom, the formula (2) can be exemplified similarly functional group described in R ^1, and preferable examples thereof are also the same.

  The specific polyurethane (2) is a group that undergoes polarity conversion from hydrophobicity to hydrophilicity by at least one of heat and acid, and preferably includes the above-mentioned thermally decomposable group (as described above, a thermally decomposable group. As a method for introducing a functional group that undergoes polarity conversion by at least one of heat and acid, as appropriate, collectively referred to as “heat / acid polarity conversion group”), (a) a raw material monomer having a heat polarity conversion group And (b) a method in which a heat / acid polarity conversion group is introduced by a polymer reaction after the polyurethane is synthesized. The methods (a) and (b) will be described with specific examples.

(A) Method of synthesizing raw material monomer having heat / acid polarity conversion group and synthesizing polyurethane using the raw material monomer Group that converts polarity from hydrophobic to hydrophilic by heat, acid decomposability which is a preferred embodiment A compound selected from a diisocyanate compound having a group and a diol compound having a heat / acid polarity conversion group is used as a raw material monomer for polyurethane, and these are made into a polyurethane, thereby having a heat / acid polarity conversion group in the side chain. A polyurethane can be obtained.

In the method of (a) polyurethane-forming a monomer having a heat / acid polarity conversion group, the diol compound preferably has a heat / acid polarity conversion group from the viewpoint of suitability for production of the monomer. Specific examples of such diol compounds are described in detail below.
A specific embodiment of a diol compound preferable as a raw material of a polyurethane having a heat / acid polarity conversion group in the side chain includes a diol compound represented by the following general formula (1).

In General Formula (1), L ¹ represents a trivalent linking group including any two or more atoms selected from a carbon atom, a hydrogen atom, an oxygen atom, a sulfur atom, and a nitrogen atom.
R ^A1 is preferably a thermopolar conversion group, preferably a functional group that serves as an acid group selected from the above-described thermally decomposable groups, that is, a carboxylic acid group, a sulfonic acid group, and a phenolic hydroxyl group, From the viewpoint of image formability and printing durability, a functional group that can be a carboxylic acid group and a phenolic hydroxyl group is more preferable. Most preferably, R ^A1 represents a group selected from the group consisting of the groups represented by General Formula (I) to General Formula (VII).

  As a more preferable embodiment of the diol compound that can be used for the synthesis of the specific polyurethane (2), a compound selected from diol compounds represented by the following general formula (5) and the following general formula (6) can be given.

In General Formula (5) and General Formula (6), L ² and L ³ each independently include any two or more atoms selected from a carbon atom, a hydrogen atom, an oxygen atom, a sulfur atom, and a nitrogen atom. And X ¹ and X ² are each independently —S—, —N (R ²⁹ ) —, —OC (═O) —N (R ³⁰ ) —, —N (R ³¹ ) C (═O) O— or —C (═O) — is represented, and R ^{19 to} R ³¹ each independently represent a hydrogen atom or a monovalent substituent. Examples of the monovalent substituent include an alkyl group, an aryl group, and an aralkyl group, and among them, a hydrogen atom, a methyl group, and an ethyl group are preferable.
R ^A1 represents a heat / acid polarity conversion group, preferably the above-described thermally decomposable group. Specific examples thereof are the same as R ^A1 in the general formula (1), and preferred examples are also the same.

Examples of the solvent used for producing a diol compound having a heat / acid polarity conversion group in the molecule include ethylene dichloride, cyclohexanone, methyl ethyl ketone, acetone, methanol, ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl glycol, 2 -Methoxyethyl acetate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-methoxy-2-propyl acetate, 1-ethoxy-2-propyl acetate, 2-butanone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, toluene, ethyl acetate, methyl lactate, ethyl lactate and the like can be mentioned.
These solvents may be used alone or in combination of two or more.

  Specific examples [Example compounds (D-1) to (VIII) -3] of preferred diol compounds as raw materials for the specific polyurethane (2) having a heat / acid polarity conversion group in the side chain are shown below. It is not limited to these.

  The above compound group can be synthesized by a general synthesis method, and the synthesis method is not limited. Hereinafter, the synthesis example is described about diol compound [Exemplary compound (I) -1].

[Synthesis Example 4: Synthesis of Exemplary Compound (I) -1]
In a 300 mL three-necked flask, 128.17 g of tert-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was weighed, and 108.16 g of thioglycerol (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 30 minutes while stirring at room temperature. After completion of dropping, the mixture was heated and stirred at 70 ° C. for 5 hours to obtain 236.33 g of Exemplified Compound (I) -1. It was confirmed from NMR, IR, and MS spectrum that the purified product was (I) -1.
The obtained exemplary compound (I) -1 is used for the next step, that is, the synthesis step of the specific polyurethane as it is without further purification.

Examples of the method for producing the specific polyurethane (2) using a diol compound and a diisocyanate compound include a method described in JP-A No. 2003-177533.
When synthesizing the specific polyurethane (2), a general polyurethane synthesis method is applied except that the diol compound having a heat / acid polarity conversion group is used as at least a part of the diol compound as a polyurethane raw material. do it.
The polyurethane resin is preferably obtained by reacting a diol having a decomposable group with a diisocyanate and another diol component as a part of the diol component.

  The polyisocyanate compound that can be used for the synthesis of the specific polyurethane (2) and the polyol compound other than the polyol compound having the heat / acid polarity conversion group (hereinafter referred to as other polyol compound) are not particularly limited. Well-known ones can be used.

The polyisocyanate compound that can be used for the synthesis of the specific polyurethane (2) is preferably a diisocyanate compound, and more preferably a compound represented by the following general formula (i).
The polyol compound that can be used in combination other than the polyol compound having the heat / acid polarity conversion group is preferably a diol compound.
The other polyol compound used for the synthesis of the specific polyurethane according to the present invention preferably includes a polyol compound having a carboxyl group, and more preferably includes a diol compound having a carboxyl group.
Preferred examples of the diol compound having a carboxyl group include diol compounds represented by the following general formula (ii) or general formula (iii).
The specific polyurethane (2) preferably has a carboxy group in addition to the aforementioned heat / acid polarity conversion group (preferably an acid-decomposable group) from the viewpoint of developability. However, if the carboxyl group content is too high, the durability of the unexposed area may be lowered. Therefore, the introduced amount of the carboxyl group is such that the acid value of the specific polyurethane (2) is 0.01 mmol / g to 2 More preferably, it is contained in the range of 0.000 mmol / g. More preferably, it is 0.10 mmol / g-1.50 mmol / g.

In general formula (i), R ¹ represents a divalent linking group. Examples of the divalent linking group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, an alkylene group having 2 to 10 carbon atoms, and an arylene group having 6 to 30 carbon atoms. Is preferred. R ¹ may have another functional group that does not react with the isocyanate group as a substituent. Examples of other functional groups that do not react with isocyanate groups include halogen atoms, aldehyde groups, ketone groups, and ester groups.
In general formula (ii), R ² represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, an alkoxy group, or an aryloxy group. Here, R ² may have a substituent. Examples of the substituent that can be introduced into R ² include a halogen atom, an aldehyde group, a ketone group, an ester group, an ether group, a thioether group, a urethane group, and a urea group.
R ² is preferably a hydrogen atom, an unsubstituted alkyl group having 1 to 8 carbon atoms, or an unsubstituted aryl group having 6 to 15 carbon atoms.
In general formula (ii) and general formula (iii), R ³ , R ⁴ and R ⁵ may be the same or different and each represents a single bond or a divalent linking group. Examples of the divalent linking group include an aliphatic hydrocarbon group and an aromatic hydrocarbon group. Here, R ³ , R ⁴ and R ⁵ have, for example, a substituent selected from a halogen atom, an aldehyde group, a ketone group, an ester group, an ether group, a thioether group, a urethane group, a urea group, and the like. May be.
Preferred examples of R ³ , R ⁴ and R ⁵ include an unsubstituted alkylene group having 1 to 20 carbon atoms or an unsubstituted arylene group having 6 to 15 carbon atoms, and an unsubstituted alkylene group having 1 to 8 carbon atoms. More preferred is an alkylene group.
In general formula (iii), Ar represents the trivalent aromatic hydrocarbon which may have a substituent, and it is preferable that it is a C6-C15 trivalent aromatic hydrocarbon group. Examples of the substituent that can be introduced into Ar include a halogen atom, an aldehyde group, a ketone group, an ester group, an ether group, a thioether group, a urethane group, and a urea group.

Specific examples of the diisocyanate compound represented by the general formula (i) include those shown below, but the present invention is not limited thereto.
2,4-tolylene diisocyanate, dimer of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylylene diisocyanate, metaxylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5 -Aromatic diisocyanate compounds such as naphthylene diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate; aliphatic diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer acid diisocyanate; Isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) -diisocyanate, 1,3- (isocyanate) And alicyclic diisocyanate compounds such as anate methyl) cyclohexane; diisocyanate compounds which are a reaction product of diol and diisocyanate such as an adduct of 1 mol of 1,3-butylene glycol and 2 mol of tolylene diisocyanate. Among these, those having an aromatic ring such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, and tolylene diisocyanate are preferable from the viewpoint of printing durability.

In addition, specific examples of the diol compound having a carboxyl group represented by the general formula (ii) or the general formula (iii) include the following, but the present invention is not limited thereto. .
3,5-dihydroxybenzoic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxyethyl) propionic acid, 2,2-bis (3-hydroxypropylpropionic acid, 2,2-bis (Hydroxymethyl) acetic acid, bis (4-hydroxyphenyl) acetic acid, 4,4-bis (4-hydroxyphenyl) pentanoic acid, tartaric acid, etc. Among them, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxyethyl) propionic acid is more preferable from the viewpoint of reactivity with isocyanate.

The specific polyurethane (2) is synthesized by adding the above-mentioned diisocyanate compound and diol compound in an aprotic solvent to a known catalyst having an activity corresponding to the reactivity and heating.
Examples of the solvent used in the synthesis of the specific polyurethane (2) include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, 1-ethoxy- 2-propyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, toluene, ethyl acetate, methyl lactate, ethyl lactate, γ -Butyrolactone etc. are mentioned. These solvents may be used alone or in combination of two or more.
The molar ratio of the diisocyanate and the diol compound to be used is preferably 0.8: 1 to 1.2: 1. When an isocyanate group remains at the polymer terminal, the final treatment is performed with an alcohol or an amine. Thus, it is synthesized in a form in which no isocyanate group remains.

Although the preferable specific example (PU-1-PU-68) of the specific polyurethane (2) which an upper layer can contain is shown by the molar ratio used with the raw material monomer and the weight average molecular weight (Mw) of the obtained specific polyurethane, Needless to say, the present invention is not limited to these examples.
In the following specific examples, the numbers described under the names of the monomers represent the molar ratio of the monomers used.

  Of the raw material monomers of PU-1 to PU-67, the diol compound having an acid polarity conversion group is the exemplified compound. Details of the polyisocyanate compound and other diol compounds are shown below.

The molecular weight of the specific polyurethane (2) is preferably 5,000 to 800,000, more preferably 10,000 to 500,000 in terms of weight average (polystyrene standard), and 20,000 to 100,000. More preferably.
The dispersity (Mw / Mn) at this time is preferably 1.0 to 20.0, more preferably 1.5 to 16.0, and preferably 2.0 to 10.0. Further preferred. When the molecular weight is in the above range, a sufficient effect can be obtained and the developability is excellent.

Below, the synthesis example of specific polyurethane PU-5 which is specific polyurethane (2) is shown.
[Synthesis Example 5: Synthesis of specific polyurethane PU-5]
In a 300 mL three-necked flask, 9.57 parts by mass of the diol compound [Exemplary Compound (I) -1] obtained in Synthesis Example 4 and DMPA (2,2-bis (hydroxymethyl) propanoic acid; manufactured by Tokyo Chemical Industry Co., Ltd.) 9.66 parts by mass and 70 parts by mass of methyl ethyl ketone were weighed and stirred at room temperature, while TDI (2,4-diisocyanate tolylene; manufactured by Tokyo Chemical Industry Co., Ltd.) 4.04 parts by mass and MDI (Millionate MT; Nippon Polyurethane). Industrial) 23.20 parts by mass and Neostan U-600 (Nitto Kasei Co., Ltd .: bismuth catalyst) 0.13 parts by mass were added in this order, and heated and stirred at 70 ° C. for 6 hours. The reaction solution was poured into 2,000 parts by mass of water to precipitate polyurethane. This was collected by filtration, washed and dried to obtain a specific polyurethane (PU-5). It was confirmed from the NMR spectrum, IR spectrum, and GPC (polystyrene conversion) that it was the target product.

  Other specific polyurethanes listed above as specific examples of the specific polyurethane (2) can be synthesized in the same manner except that the raw material monomers used are changed as described above.

(B) Method of introducing heat / acid polarity conversion group by polymer reaction after synthesis of polyurethane Polyurethane having a reactive group in the side chain which does not pose a problem during the synthesis of polyurethane, and the reactive group in the obtained polyurethane A polyurethane having a heat / acid polarity conversion group in the side chain can be obtained by reacting with the compound having both the group reacting with and optionally the above-mentioned heat / acid polarity conversion group.
Examples of the reactive group that does not cause a problem during the synthesis of the polyurethane include a carboxylic acid group, a halogen atom, an aldehyde group, a ketone group, and an ester group. The group that reacts with the reactive group in the polyurethane includes a vinyl ether group. , Amino groups, thiol groups, and the like.

  Hereinafter, the synthesis of the specific polyurethane (2) using a method of introducing a heat / acid polarity conversion group by a polymer reaction will be described with an example.

[Synthesis Example 6: Synthesis of specific polyurethane PU-23]
In a 300 mL three-necked flask, 15.42 parts by mass of DMPA (2,2-bis (hydroxymethyl) propanoic acid; manufactured by Tokyo Chemical Industry) and 173 parts by mass of methyl ethyl ketone were weighed and stirred at room temperature (25 ° C.). However, 4.13 parts by mass of TDI (2,4-diisocyanate tolylene; manufactured by Tokyo Chemical Industry) and 23.71 parts by mass of MDI (Millionate MT; manufactured by Nippon Polyurethane Industry), Neostan U-600 (Nitto Kasei Co., Ltd.) (Product: Bismuth catalyst) 0.13 parts by mass were added in this order, and the mixture was heated and stirred at 70 ° C. for 6 hours. Thereafter, 0.01 parts by mass of (+)-10-camphorsulfonic acid (manufactured by Tokyo Chemical Industry) and 4.14 parts by mass of butyl vinyl ether (manufactured by Tokyo Chemical Industry) are added to the reaction solution at room temperature over 30 minutes. The solution was added dropwise and reacted at 30 ° C. for 2 hours. The reaction solution was poured into an aqueous solution consisting of 10 parts by weight of sodium hydrogen carbonate and 2,000 parts by weight of water to precipitate polyurethane. This was collected by filtration, washed and dried to obtain a specific polyurethane (PU-23). It was confirmed from the NMR spectrum, IR spectrum, and GPC (polystyrene conversion) that it was the target product.

  Further, the content of the specific polyurethane contained in the upper layer is preferably 2.05% by mass to 99.5% by mass in the total solid content of the upper layer, and is 10.05% by mass to 99.0% by mass. It is more preferable that the content is 20.05% by mass to 90.0% by mass. This improves printing durability as well as image formability.

  Here, the “total solid content of the upper layer” means all components excluding the solvent among the components contained in the upper layer.

  As long as the effects of the present invention are not impaired, the upper layer may contain an alkali-soluble resin other than the specific polyurethane. Examples of the other alkali-soluble resins include alkali-soluble resins such as lyamide resins, epoxy resins, polyacetal resins, acrylic resins, methacrylic resins, polystyrene resins, and novolac phenolic resins.

  When the upper layer contains another alkali-soluble resin, the content is preferably 20% by mass or less based on the total solid content of the upper layer.

  The upper layer preferably further contains an infrared absorber, an acid generator, an acid proliferator and the like. The components that are preferably included in the upper layer will be described below.

<< Infrared absorber >>
The lithographic printing plate precursor according to the invention may contain an infrared absorber in the upper layer. By containing an infrared absorber in the upper layer, the sensitivity is further improved.
The infrared absorber is not particularly limited as long as it is a dye or pigment that absorbs infrared light and generates heat, and the above-described infrared absorbers that can be used in the lower layer can be used in the same manner.
A particularly preferable dye is the cyanine dye A.

  The content of the infrared absorber in the upper layer is preferably 0.01% by mass to 50% by mass with respect to the total solid content of the upper layer, from the viewpoints of sensitivity, layer uniformity, and durability. It is more preferable that it is mass%-30 mass%, and it is especially preferable that it is 1.0 mass%-30 mass%.

<Acid generator>
The upper layer preferably contains an acid generator from the viewpoint of improving sensitivity.
In this invention, an acid generator is a compound which generate | occur | produces an acid with light or a heat | fever, and points out the compound which decomposes | disassembles and generate | occur | produces an acid by infrared irradiation or a heating of 100 degreeC or more. The acid generated is preferably a strong acid having a pKa of 2 or less, such as sulfonic acid and hydrochloric acid. The acid generated from the acid generator functions as a catalyst, the chemical bond in the acid-decomposable group is cleaved to become an acid group, and the solubility in the upper alkaline aqueous solution is further improved.

Examples of the acid generator suitably used in the present invention include onium salts such as iodonium salts, sulfonium salts, phosphonium salts, and diazonium salts. Specific examples include compounds described in US Pat. No. 4,708,925 and JP-A-7-20629. In particular, iodonium salts, sulfonium salts, and diazonium salts having a sulfonate ion as a counter ion are preferable. Examples of the diazonium salt include diazonium compounds described in U.S. Pat. No. 3,867,147, diazonium compounds described in U.S. Pat. No. 2,632,703, and JP-A-1-102456 and JP-A-1-102457. The diazo resin described in the publication is also preferable. Also preferred are benzyl sulfonates described in US Pat. No. 5,135,838 and US Pat. No. 5,200,544. Furthermore, active sulfonic acid esters and disulfonyl compounds described in JP-A-2-100054, JP-A-2-100055 and Japanese Patent Application No. 8-9444 are also preferable. In addition, haloalkyl-substituted S-triazines described in JP-A-7-271029 are also preferable.
Further, the compound described as “acid precursor” in JP-A-8-220552 or “(a) a compound capable of generating an acid upon irradiation with active light” in JP-A-9-171254 And the like can be applied as the acid generator of the present invention.

Among these, from the viewpoint of sensitivity and stability, it is preferable to use an onium salt compound as the acid generator. Hereinafter, the onium salt compound will be described.
Examples of the onium salt compound that can be suitably used in the present invention include compounds known as compounds that generate an acid by being decomposed by thermal energy generated from an infrared absorber upon exposure to infrared light. Examples of the onium salt compound suitable for the present invention include known thermal polymerization initiators and compounds having an onium salt structure described below having a bond with small bond dissociation energy from the viewpoint of sensitivity.
Examples of the onium salt suitably used in the present invention include known diazonium salts, iodonium salts, sulfonium salts, ammonium salts, pyridinium salts, azinium salts, and the like. Among them, triarylsulfonium or diaryliodonium sulfonic acid Salt, carboxylate, BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ^{− and the} like are preferable.
Examples of the onium salt that can be used as the acid generator in the present invention include onium salts represented by the following general formulas (x) to (xii).

In general formula (x), Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a carbon atom having 12 or less carbon atoms. An aryloxy group is mentioned. Z ¹¹⁻ is a counter ion selected from the group consisting of halogen ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, sulfonate ions, and sulfonate ions having fluorine atoms, such as perfluoroalkylsulfonate ions. And are preferably perchlorate ion, hexafluorophosphate ion, aryl sulfonate ion, and perfluoroalkyl sulfonic acid.
In the general formula (xi), Ar ²¹ represents an aryl group having 20 or less carbon atoms. Ar ²¹ may have a substituent. Z ^21- represents a counter ion having the same ^meaning as Z ^11- .
In the general formula (xii), R ³¹ , R ³² and R ³³ each represent a hydrocarbon group having 20 or less carbon atoms. These may have a substituent.

  In the present invention, onium salts represented by general formula (x) ([OI-1] to [OI-6]) and onium salts represented by general formula (xi) ([ON-1]) that can be suitably used. To [ON-2]), and specific examples of onium salts ([OS-1] to [OS-4]) represented by the general formula (xii) are given below.

  Further, as another example of the compound represented by the general formula (x) to the general formula (xii), in paragraphs [0036] to [0045] of JP-A-2008-195018, examples of radical polymerization initiators The described compounds can be suitably used as the acid generator in the present invention.

  Another example of an onium salt preferable as the acid generator used in the present invention is an azinium salt compound represented by the following general formula (xiii).

In general formula (xiii), R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ , and R ⁴⁶ may be the same or different and each represents a hydrogen atom, a halogen atom, or a monovalent substituent. .
Monovalent substituents include, for example, halogen atoms, amino groups, substituted amino groups, substituted carbonyl tombs, hydroxyl groups, substituted oxy groups, thiol groups, thioether groups, silyl groups, nitro groups, cyano groups, alkyl groups, alkenyl groups. , Aryl group, heterocyclic group, sulfo group, substituted sulfonyl group, sulfonate group, substituted sulfinyl group, phosphono group, substituted phosphono group, phosphonato group, substituted phosphonato group, etc. You may have.

As the compound represented by the general formula (xiii), a skeleton (cation part) having a specific structure in the compound represented by the general formula (xiii) is bonded via R ⁴¹ , and two cation parts are present in the molecule. The compounds contained above (multimeric forms) are also included, and such compounds are also preferably used.
Z ⁴¹⁻ represents a counter ion having the same ^meaning as Z ¹¹⁻ .
Specific examples of the azinium salt compound represented by the general formula (xiii) include compounds described in paragraph numbers [0047] to [0056] of JP-A-2008-195018.
The N—O bond described in JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537, and JP-B-46-42363 is also disclosed. A group of compounds having the above is also suitably used as the acid generator in the present invention.
More preferable examples of the acid generator that can be used in the present invention include the following compounds (PAG-1) to (PAG-5).

When these acid generators are contained in the upper layer, these acid generators may be used alone or in combination of two or more.
When the acid generator is contained in the upper layer, the preferable content is 0.01% by mass to 50% by mass with respect to the total solid content of the upper layer, more preferably 0.1 to 40% by mass, and still more preferably 0%. It is the range of 5-30 mass%. When the addition amount is in the above range, an improvement in sensitivity, which is an effect of addition of an acid generator, is observed, and generation of a residual film in a non-image area is suppressed.

[Acid multiplication agent]
An acid proliferating agent may be added to the upper layer.
The acid proliferating agent in the present invention is a compound substituted with a relatively strong acid residue, and is a compound that is easily eliminated in the presence of an acid catalyst to newly generate an acid. That is, it decomposes by an acid catalyst reaction and generates an acid (hereinafter referred to as ZOH in the general formula) again. One or more acids are increased in one reaction, and the sensitivity is dramatically improved by increasing the acid concentration at an accelerated rate as the reaction proceeds. The strength of the generated acid is 3 or less as an acid dissociation constant (pKa), and preferably 2 or less. If the acid is weaker than this, an acid-catalyzed elimination reaction cannot be caused.
Examples of the acid used for such an acid catalyst include dichloroacetic acid, trichloroacetic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, and phenylsulfonic acid.

  Examples of the acid proliferating agent include WO95 / 29968, WO98 / 24000, JP-A-8-305262, JP-A-9-34106, JP-A-8-248561, JP-A-8-503082, and US Pat. No. 5,445. No. 9,917, JP-A-8-503081, US Pat. No. 5,534,393, US Pat. No. 5,395,736, US Pat. No. 5,741,630, US Pat. No. 5,334,489 , U.S. Patent No. 5,582,956, U.S. Patent No. 5,578,424, U.S. Patent No. 5,453,345, U.S. Patent No. 5,445,917, European Patent No. 665,960, EP 757,628, EP 665,961, U.S. Pat. No. 5,667,943, JP-A-10-1598, etc. It is possible to have.

  Preferable specific examples of the acid proliferating agent in the present invention include compounds described in paragraph numbers [0056] to [0067] of JP-A No. 2001-66765. Especially, the following compound described as exemplary compound (ADD-1), (ADD-2), (ADD-3) can be used conveniently.

  As an addition amount in the case of adding these acid proliferating agents in the upper layer, in terms of solid content, 0.01 to 20% by mass, preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass. % Range. When the amount of the acid proliferating agent is within the above range, the effect of adding the acid proliferating agent is sufficiently obtained, the sensitivity is improved, the decrease in the film strength of the image area is suppressed, and the excellent film resulting from the specific polyurethane Strength is maintained.

  Furthermore, in the upper layer in the present invention, other components may be used in combination as long as the effects of the present invention are not impaired.

<Other additives>
In forming the lower layer and the upper layer, in addition to the above-described essential components, various other additives can be further added as necessary as long as the effects of the present invention are not impaired. The additives listed below may be added only to the lower layer, may be added only to the upper layer, or may be added to both the upper layer and the lower layer.

<< Development accelerator >>
For the purpose of improving sensitivity, acid anhydrides, phenols, and organic acids may be added to the upper layer and the lower layer.
As the acid anhydrides, cyclic acid anhydrides are preferable. Specific examples of the cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydro anhydride described in US Pat. No. 4,115,128. Phthalic acid, 3,6-endooxytetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Examples of acyclic acid anhydrides include acetic anhydride.
Examples of phenols include bisphenol A, 2,2′-bishydroxysulfone, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4- Examples include hydroxybenzophenone, 4,4 ′, 4 ″ -trihydroxytriphenylmethane, 4,4 ′, 3 ″, 4 ″ -tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane. .
Examples of the organic acids are described in JP-A-60-88942, JP-A-2-96755, and the like. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, Ethyl sulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene Examples include -1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like.
The proportion of the acid anhydride, phenols and organic acids in the total solid content of the lower or upper layer is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, and 0.1 to 10%. Mass% is particularly preferred.

<< Surfactant >>
The upper layer and the lower layer are described, for example, in JP-A Nos. 62-251740 and 3-208514 in order to improve the coatability and to increase the stability of processing with respect to development conditions. Such nonionic surfactants, amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149 can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like.
Specific examples of amphoteric activators include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).
The proportion of the surfactant in the total solid content of the lower layer or the upper layer is preferably 0.01% by mass to 15% by mass, more preferably 0.01% by mass to 5% by mass, and 0.05% by mass to 2.0%. More preferred is mass%.

<< Bakeout agent / Colorant >>
In the upper layer and the lower layer, a printing-out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image coloring agent can be added.
A representative example of the printing-out agent is a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt. Examples of the photoacid releasing agent include o-naphthoquinonediazide-4-sulfonic acid halide, and triazine compounds and trihalomethyl compounds as oxazole compounds.
As the colorant, other known dyes can be used in addition to the aforementioned salt-forming organic dyes. Examples of suitable dyes including salt-forming organic dyes include oil-soluble dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet Lactone, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI52015), etc. Can do. Further, the dyes described in JP-A-62-293247 are particularly preferred.
These dyes are preferably added in a proportion of 0.01% by mass to 10% by mass, and added in a proportion of 0.1% by mass to 3% by mass with respect to the total solid content of the upper layer or the lower layer. Is more preferable.

<< Plasticizer >>
A plasticizer may be added to the upper layer and the lower layer in order to impart flexibility and the like of the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid These oligomers and polymers are used.
These plasticizers are preferably added in a proportion of 0.5% by mass to 10% by mass and added in a proportion of 1.0% by mass to 5% by mass with respect to the total solid content of the upper layer or the lower layer. It is more preferable.

<< Wax agent >>
In the upper layer, a compound that lowers the static friction coefficient of the surface can be added for the purpose of imparting resistance to scratches. Specifically, as described in US Pat. No. 6,117,913, JP-A No. 2003-149799, JP-A No. 2003-302750, or JP-A No. 2004-12770, A compound having an ester of a long-chain alkyl carboxylic acid can be exemplified.
The amount of the wax agent added is preferably 0.1% by mass to 10% by mass and more preferably 0.5% by mass to 5% by mass with respect to the total solid content of the upper layer. preferable.

<Formation of recording layer>
The recording layer in the lithographic printing plate precursor according to the invention is usually prepared by coating or coating the coating solution on a suitable support by dissolving or dispersing the components contained in the lower layer or the upper layer in a solvent. Can be formed.

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

The lower layer and the upper layer are formed by sequentially coating the two layers.
Specifically, an alkali-soluble resin, a fluoroaliphatic group-containing copolymer, an optional component added as necessary, and a lower layer coating solution containing a solvent are prepared, and the lower layer coating solution is formed on a support. After coating and drying to form a lower layer, preparing an upper layer coating solution containing a specific polyurethane, optional components added if necessary, and a solvent, and applying and drying the upper layer coating solution on the lower layer, It is preferable to form an upper layer and a lower layer.
By forming the lower layer as described above, the uneven distribution of the fluoroaliphatic group-containing copolymer in the vicinity of the interface with the upper layer in the lower layer becomes prominent before the upper layer is formed. For this reason, when the upper layer is formed, inter-layer mixing between the upper layer and the lower layer is effectively suppressed, so that a recording layer in which the upper layer and the lower layer are clearly separated can be formed.

Furthermore, in the formation of the upper layer and the lower layer, for example, a method using the difference in solvent solubility between the component constituting the lower layer and the component constituting the upper layer, or after applying the lower layer, the solvent is rapidly dried. A method of providing an upper layer after removal may be used in combination. As a method of utilizing the difference in solvent solubility between the component constituting the lower layer and the component constituting the upper layer, the upper layer coating liquid is applied after the lower layer is applied. Is a method using a solvent system in which any of the components constituting the lower layer is insoluble. Thereby, it becomes possible to make the coating film which separated the upper layer and the lower layer more clearly.

  Next, after applying the second layer (upper layer), as a method of drying the solvent very quickly, high-pressure air is blown from a slit nozzle installed substantially perpendicular to the web traveling direction, or heating such as steam is performed. It can be achieved by applying thermal energy as conduction heat from the lower surface of the web from a roll (heating roll) supplied inside the medium, or a method of combining them.

It is preferable that the density | concentration of the said component (total solid content including an additive) except the solvent in the lower layer applied on a support body and each coating liquid for upper layers is 1-50 mass%.
Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
In particular, in order to prevent damage to the lower layer, which is the first layer, when the upper layer, which is the second layer, is applied, the second layer is preferably applied in a non-contact manner. In addition, although it is a contact type, it is possible to use bar coater coating as a method generally used for solvent-based coating, but it is preferable to apply by forward rotation in order to prevent damage to the first layer. .

The solid coating amount after the underlying drying ^is preferably in the range of ^{0.3g / m 2 ~5.0g / m 2} , in the range of 0.5g / ^{m 2} ~3.0g / m 2 range are more preferred solid coating amount after drying of the upper layer ^is a preferably in the range of ^{0.05g / m 2 ~2.0g / m 2} , 0.1g / m 2 ~1.0g / m 2 It is more preferable that
Moreover, 0.05-1 are preferable and, as for ratio (upper layer / lower layer) of the coating amount of an upper layer and a lower layer, More preferably, it is the range of 0.1-0.8.

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

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

Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements.
Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is preferably 0.1 to 0.6 mm, more preferably 0.15 to 0.4 mm, and particularly preferably 0.2 to 0.3 mm. preferable.

Such an aluminum plate may be subjected to a surface treatment such as a roughening treatment or an anodizing treatment as necessary. Hereinafter, such a surface treatment will be briefly described.
Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used.
The aluminum plate roughened as described above is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodizing treatment if desired in order to enhance the water retention and wear resistance of the surface. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm ^2. The voltage is preferably in the range of 1 to 100 V and the electrolysis time of 10 seconds to 5 minutes. The amount of the anodized film is preferably 1.0 g / m ² or less. When it is 1.0 g / m ² or less, the printing durability is excellent, the non-image portion of the lithographic printing plate is hardly scratched, and so-called “scratch stain” in which ink adheres to the scratched portion during printing is suppressed. it can.
After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary.

  Examples of the hydrophilization treatment used in the present invention include U.S. Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There are alkali metal silicate (e.g., aqueous sodium silicate) methods as disclosed in the specification. In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and U.S. Pat. Nos. 3,276,868, 4,153,461, and 4,689,272 For example, a method of treating with polyvinylphosphonic acid as disclosed in the literature is used.

<Undercoat layer>
The lithographic printing plate precursor according to the present invention is provided by laminating two layers, a lower layer and an upper layer, as a recording layer having a multilayer structure on a support, and a lower layer is provided between the support and the lower layer as necessary. A coating layer can be provided.
As an undercoat layer component, various organic compounds are used. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, and phenylphosphone which may have a substituent. Acid, naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, organic phosphonic acid such as methylenediphosphonic acid and ethylenediphosphonic acid, phenylphosphonic acid, naphthylphosphoric acid, alkylphosphoric acid and glycerophosphoric acid optionally having substituents Organic phosphoric acid such as phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and triethanolamine Hydroxy, such as hydrochloride Hydrochlorides of amines having a are preferably exemplified. These undercoat layer components may be used alone or in combination of two or more.

This undercoat layer 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 applied on an aluminum plate and dried to provide a solution, and water, methanol, ethanol, methyl ethyl ketone, etc. In this method, an aluminum plate is immersed in a solution obtained by dissolving the above organic compound in the above organic solvent or a mixed solvent thereof to adsorb the above compound, and then washed and dried with water or the like to provide an undercoat layer. In the former method, a solution having a concentration of 0.005 to 10% by mass of the organic compound can be applied by various methods. In the latter method, the concentration of the solution is preferably 0.01 to 20% by mass, more preferably 0.05 to 5% by mass, and the immersion temperature is preferably 20 to 90 ° C., more preferably 25 to 50 ° C. The immersion time is preferably 0.1 second to 20 minutes, more 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 coating amount of the undercoat layer is ^dried, is preferably ^{2mg / m 2 ~200mg / m 2} , and more preferably ^{5mg / m 2 ~100mg / m 2} . When the coating amount after drying is in the above range, sufficient printing durability can be obtained.
The lithographic printing plate precursor produced as described above is imagewise exposed and then developed.

<Back coat layer>
A back coat layer is provided on the back surface of the support of the lithographic printing plate precursor according to the invention, if necessary. Such a back coat layer comprises a metal oxide obtained by hydrolysis and polycondensation of an organic polymer compound described in JP-A-5-45885 and an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Among these coating layers, silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , and Si (OC ₄ H ₉ ) ₄ are available at a low price. The coating layer of the metal oxide obtained therefrom is particularly preferable because of its excellent developer resistance.

(Plate making method of lithographic printing plate)
The lithographic printing plate production method of the present invention comprises an exposure step of exposing the infrared-sensitive positive lithographic printing plate precursor of the present invention imagewise with infrared rays, and an alkaline aqueous solution (developer) having a pH of 8.5 to 13.5. It is preferable to include a development step in which the development is performed in this order.
The planographic printing plate of the present invention is a planographic printing plate obtained by the plate making method of the planographic printing plate of the present invention.

<Exposure process>
The plate-making method of the lithographic printing plate of the present invention preferably includes an exposure step for image exposure of the infrared-sensitive positive lithographic printing plate precursor of the present invention.
The actinic ray light source used for image exposure of the lithographic printing plate precursor according to the present invention is preferably a light source having an emission wavelength in the near infrared to infrared region, and more preferably a solid laser or a semiconductor laser. Among them, in the present invention, it is particularly preferable that the image exposure is performed by a solid laser or a semiconductor laser that emits infrared rays having a wavelength of 750 to 1,400 nm.
The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec.
Energy irradiated on the planographic printing plate precursor is preferably ^{10mJ / cm 2 ~500mJ / cm 2} .

  The exposure in the present invention can be performed by overlapping the light beams of the light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the full width at half maximum (FWHM) of the beam intensity. In the present invention, the overlap coefficient is preferably 0.1 or more.

  The scanning method of the light source of the exposure apparatus that can be used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, and the like can be used. The channel of the light source may be a single channel or a multi-channel, but in the case of a cylindrical outer surface system, a multi-channel is preferably used.

<Development process>
The plate making method of the lithographic printing plate of the present invention preferably includes a developing step of developing using a developer.
The developer used in the development step (hereinafter also referred to as “processing solution”) is preferably an aqueous solution having a pH of 6 to 13.5, and more preferably an alkaline aqueous solution having a pH of 8.5 to 13.5. The developer preferably contains a surfactant, and more preferably contains at least an anionic surfactant or a nonionic surfactant. Surfactant contributes to the improvement of processability.
As the surfactant used in the developer, any of anionic, nonionic, cationic, and amphoteric can be used.
Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinates, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates. , Alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamide disodium salts, petroleum sulfonates, sulfated castor oil , Sulfated tallow oil, fatty acid alkyl ester sulfate ester salt, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, polyoxyethylene naphthyl -Ter sulfate, fatty acid monoglyceride sulfate, polyoxyethylene alkylphenyl ether sulfate, polyoxyethylene styrylphenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkylphenyl Ether phosphoric acid ester salts, saponified fractions of styrene-maleic anhydride copolymer, partial saponified products of olefin-maleic anhydride copolymer, naphthalene sulfonate formalin condensates, aromatic sulfonates, aromatic Examples include substituted polyoxyethylene sulfonates. Among these, dialkyl sulfosuccinates, alkyl sulfate esters, alkyl naphthalene sulfonates, and polyoxyethylene naphthyl ether sulfates are particularly preferably used.

  The cationic surfactant is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

  Nonionic surfactants include polyethylene glycol type higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, polyethylene glycol adducts of aromatic compounds, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, Higher alkylamine ethylene oxide adduct, fatty acid amide ethylene oxide adduct, oil and fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, etc. And polyhydric alcohol glycerol fatty acid ester, pentaerythritol fatty acid ester, Rubitoru and fatty acid esters of sorbitan, fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, fatty acid amides of alkanolamines.

  In the present invention, ethylene oxide adduct of sorbitol and / or sorbitan fatty acid ester, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, polyhydric alcohol More preferred are fatty acid esters and polyethylene glycol adducts of aromatic compounds.

  Moreover, from the viewpoint of stable solubility or turbidity in water, the HLB value is preferably 6 or more, and more preferably 8 or more.

As is well known in the field of surfactants, amphoteric surfactants are compounds having an anionic moiety and a cationic moiety in the same molecule, and are amphoteric such as amino acids, betaines, and amine oxides. A surfactant is included.
As the amphoteric surfactant that can be used in the developer, a compound represented by the following formula <1> and a compound represented by the following formula <2> are preferable.

In formula <1>, R ⁸ represents an alkyl group, R ⁹ and R ¹⁰ each independently represents a hydrogen atom or an alkyl group, R ¹¹ represents an alkylene group, and A represents a carboxylate ion or a sulfonate ion. Represent.
In formula <2>, R ¹⁸ , R ¹⁹ and R ²⁰ each independently represents a hydrogen atom or an alkyl group. However, not all of R ¹⁸ , R ¹⁹ and R ²⁰ are hydrogen atoms.

In the above formula <1>, the alkyl group in R ⁸ , R ⁹ or R ¹⁰ and the alkylene group in R ¹¹ may be linear or branched, and may have a linking group in the chain. In addition, it may further have a substituent. As the linking group, those containing a hetero atom such as an ester bond, an amide bond, or an ether bond are preferable. Moreover, as a substituent, a hydroxyl group, an ethylene oxide group, a phenyl group, an amide group, a halogen atom, etc. are preferable.
In the compound represented by the formula <1>, the total number of carbon atoms of R ^{8 to} R ¹¹ is preferably 8 to 25, and more preferably 11 to 21. Within the above range, the hydrophobic portion is appropriate and the solubility in an aqueous developer is excellent.
It is also possible to increase the solubility of the surfactant in an aqueous developer by adding an organic solvent, for example, a solubilizing agent such as alcohol.

In the above formula <2>, the alkyl group in R ¹⁸ , R ¹⁹ or R ²⁰ may be linear or branched, may have a linking group in the chain, and further has a substituent. You may do it. As the linking group, those containing a hetero atom such as an ester bond, an amide bond, or an ether bond are preferable. Moreover, as a substituent, a hydroxyl group, an ethylene oxide group, a phenyl group, an amide group, a halogen atom, etc. are preferable.
In the compound represented by the formula <2>, the total number of carbon atoms of R ^{18 to} R ²⁰ is preferably 8 to 22, and more preferably 10 to 20. Within the above range, the hydrophobic portion is appropriate and the solubility in an aqueous developer is excellent.

  The total carbon number of the amphoteric surfactant may be affected by the material used for the recording layer, particularly the properties of the binder. In the case of a binder having a high degree of hydrophilicity, those having a relatively small total carbon number are preferred, and when the binder used has a low degree of hydrophilicity, those having a large total carbon number tend to be preferred.

  Preferable specific examples of the amphoteric surfactant that can be used in the developer are shown below, but the present invention is not limited thereto.

As the surfactant used in the developer, an anionic surfactant is more preferable, and an anionic surfactant containing a sulfonic acid or a sulfonate is particularly preferable.
Surfactants can be used alone or in combination.
The content of the surfactant in the developer is preferably from 0.01 to 10% by mass, and more preferably from 0.01 to 5% by mass.

In order to maintain the developer at pH 6 to 13.5, the presence of carbonate ions and hydrogen carbonate ions as buffering agents can suppress pH fluctuations even when the developer is used for a long period of time. It is possible to suppress deterioration in properties, development residue, etc. In order to allow carbonate ions and hydrogen carbonate ions to be present in the developer, carbonate and hydrogen carbonate may be added to the developer, or by adjusting the pH after adding carbonate or bicarbonate, Ions and bicarbonate ions may be generated. The carbonate and bicarbonate are not particularly limited, but are preferably alkali metal salts. Examples of the alkali metal include lithium, sodium, and potassium, and sodium is particularly preferable. These may be used alone or in combination of two or more.
The pH of the developer is not particularly limited as long as it can be developed, but is preferably in the range of pH 8.5 to 13.5.

  The total amount of carbonate and bicarbonate is preferably 0.3 to 20% by mass, more preferably 0.5 to 10% by mass, and particularly preferably 1 to 5% by mass with respect to the total mass of the developer. When the total amount is 0.3% by mass or more, developability and processing capacity do not decrease, and when it is 20% by mass or less, it becomes difficult to form precipitates and crystals. It becomes difficult to gel and does not interfere with waste liquid treatment.

Further, for the purpose of assisting the fine adjustment of the alkali concentration and the dissolution of the non-image area photosensitive layer, another alkali agent such as an organic alkali agent may be supplementarily used together. Examples of the organic alkali agent include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, Examples thereof include diisopropanolamine, ethyleneimine, ethylenediamine, pyridine, tetramethylammonium hydroxide and the like. These other alkaline agents are used alone or in combination of two or more.
In addition to the above, the developer may contain a wetting agent, preservative, chelate compound, antifoaming agent, organic acid, organic solvent, inorganic acid, inorganic salt, and the like. However, when a water-soluble polymer compound is added, the plate surface tends to be sticky especially when the developer is fatigued.

  As the wetting agent, ethylene glycol, propylene glycol, triethylene glycol, butylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, diglycerin and the like are preferably used. The wetting agent may be used alone or in combination of two or more. The wetting agent is preferably used in an amount of 0.1 to 5% by mass relative to the total mass of the developer.

  Preservatives include phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzoisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, benztriazole derivatives Amiding anidine derivatives, quaternary ammonium salts, pyridine, quinoline, guanidine and other derivatives, diazines, triazole derivatives, oxazoles, oxazine derivatives, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3diols, 1 1,1-dibromo-1-nitro-2-ethanol, 1,1-dibromo-1-nitro-2-propanol and the like can be preferably used. It is preferable to use two or more kinds of preservatives in combination so as to be effective against various molds and sterilization. The addition amount of the preservative is an amount that exhibits a stable effect on bacteria, fungi, yeast, etc., and varies depending on the type of bacteria, fungi, yeast, etc., but is 0 with respect to the total mass of the developer. The range of 0.01 to 4% by mass is preferable.

  Examples of the chelate compound include ethylenediaminetetraacetic acid, potassium salt thereof, sodium salt thereof; diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof; triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof, hydroxyethylethylenediaminetriacetic acid Nitrilotriacetic acid, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri (methylenephosphonic acid), potassium salt, sodium salt And organic phosphonic acids such as phosphonoalkanetricarboxylic acids. An organic amine salt is also effective in place of the sodium salt and potassium salt of the chelating agent. A chelating agent is selected that is stably present in the developer composition and does not impair the printability. The addition amount is preferably 0.001 to 1.0 mass% with respect to the total mass of the developer.

  As the antifoaming agent, a general silicone-based self-emulsifying type, emulsifying type, or nonionic compound can be used, and a compound having an HLB value of 5 or less is preferable. Silicone defoamers are preferred. Among them, emulsification dispersion type and solubilization can be used. The content of the antifoaming agent is preferably in the range of 0.001 to 1.0% by mass with respect to the total mass of the developer.

  Examples of organic acids include citric acid, acetic acid, succinic acid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malic acid, lactic acid, levulinic acid, p-toluenesulfonic acid, xylenesulfonic acid, phytic acid, and organic phosphonic acid. . The organic acid can also be used in the form of its alkali metal salt or ammonium salt. The content of the organic acid is preferably 0.01 to 0.5% by mass with respect to the total mass of the developer.

  Examples of the organic solvent include aliphatic hydrocarbons (hexane, heptane, “Isopar E, H, G” (Esso Chemical Co., Ltd.), gasoline, kerosene, etc.), aromatic hydrocarbons (toluene, Xylene, etc.), halogenated hydrocarbons (methylene dichloride, ethylene dichloride, trichlene, monochlorobenzene, etc.) and polar solvents.

  Polar solvents include alcohols (methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol monomethyl ether, 2-ethoxyethanol, etc.), ketones (methyl ethyl ketone, cyclohexanone, etc.), esters (ethyl acetate, methyl lactate, propylene) Glycol monomethyl ether acetate, etc.) and others (triethyl phosphate, tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, etc.).

  When the organic solvent is insoluble in water, it can be used after being solubilized in water using a surfactant or the like. When the developer contains an organic solvent, the concentration of the solvent is preferably less than 40% by mass from the viewpoint of safety and flammability.

  Examples of inorganic acids and inorganic salts include phosphoric acid, metaphosphoric acid, primary ammonium phosphate, secondary ammonium phosphate, primary sodium phosphate, secondary sodium phosphate, primary potassium phosphate, secondary potassium phosphate, Examples thereof include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogen sulfate, nickel sulfate and the like. The content of the inorganic salt is preferably 0.01 to 0.5% by mass with respect to the total mass of the developer.

  The development temperature is not particularly limited as long as development is possible, but it is preferably 60 ° C. or lower, more preferably 15 to 40 ° C. In the development processing using an automatic developing machine, the developing solution may be fatigued depending on the processing amount. Therefore, the processing capability may be restored using a replenishing solution or a fresh developing solution. An example of development and post-development processing is a method in which alkali development is performed, alkali is removed in a post-water washing step, gumming is performed in a gumming step, and drying is performed in a drying step. As another example, a method in which pre-water washing, development and gumming are simultaneously performed by using an aqueous solution containing carbonate ions, hydrogen carbonate ions and a surfactant can be preferably exemplified. Therefore, the pre-water washing step is not particularly required, and it is preferable to perform the drying step after performing pre-water washing, development and gumming in one bath only by using one liquid. After development, it is preferable to dry after removing excess developer using a squeeze roller or the like.

  The development process can be preferably carried out by an automatic processor equipped with a rubbing member. As an automatic processor, for example, an automatic processor described in JP-A-2-220061 and JP-A-60-59351, which performs a rubbing process while conveying a lithographic printing plate precursor after image exposure, or a cylinder Examples thereof include an automatic processor described in US Pat. Nos. 5,148,746, 5,568,768 and British Patent 2,297,719, which rub the lithographic printing plate precursor after image exposure set above while rotating a cylinder. Among these, an automatic processor using a rotating brush roll as the rubbing member is particularly preferable.

The rotating brush roll used in the present invention can be appropriately selected in consideration of the difficulty of scratching the image area and the strength of the waist of the lithographic printing plate precursor. As the rotating brush roll, a known one formed by planting a brush material on a plastic or metal roll can be used. For example, a metal or plastic in which brush materials are implanted in a row, as described in JP-A-58-159533, JP-A-3-100554, or JP-A-62-167253 A brush roll in which the groove mold material is radially wound around a plastic or metal roll as a core without any gap can be used.
Examples of brush materials include plastic fibers (for example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6.6 and nylon 6.10, polyacrylics such as polyacrylonitrile and poly (meth) acrylate). , Polyolefin-based synthetic fibers such as polypropylene and polystyrene). For example, fiber diameters of 20 to 400 μm and hair lengths of 5 to 30 mm can be suitably used.
The outer diameter of the rotating brush roll is preferably 30 mm to 200 mm, and the peripheral speed of the tip of the brush rubbing the plate surface is preferably 0.1 m / sec to 5 m / sec. It is preferable to use a plurality of rotating brush rolls.

  The rotating direction of the rotating brush roll may be the same or opposite to the conveying direction of the lithographic printing plate precursor. However, when two or more rotating brush rolls are used, at least one rotating brush roll is used. It is preferred that the rotating brush rolls rotate in the same direction and at least one rotating brush roll rotates in the opposite direction. This further ensures the removal of the photosensitive layer in the non-image area. It is also effective to swing the rotating brush roll in the direction of the rotation axis of the brush roll.

  It is preferable to provide a drying step continuously or discontinuously after the development step. Drying is performed by hot air, infrared rays, far infrared rays, or the like.

Further, for the purpose of improving printing durability, the developed printing plate can be heated under very strong conditions. The heating temperature is usually in the range of 200 to 500 ° C. If the temperature is low, sufficient image strengthening action cannot be obtained, and if it is too high, problems such as deterioration of the support and thermal decomposition of the image area may occur.
The lithographic printing plate obtained in this way is applied to an offset printing machine and is suitably 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. Unless otherwise specified, “part” and “%” are based on mass.

[Example 1]
(Production of support)
An aluminum plate (material: JIS A 1050) with a thickness of 0.3 mm is etched for 10 seconds at a caustic soda concentration of 30 g / l, an aluminum ion concentration of 10 g / l, and a liquid temperature of 60 ° C., washed with running water, and washed with 10 g / l nitric acid. After neutralizing and washing with water. Using an alternating waveform current of sine wave under the condition of applied voltage Va = 20 V, an electric current of 400 C / dm ² in an aqueous solution having a hydrogen chloride concentration of 15 g / l, an aluminum ion concentration of 10 g / l, and a liquid temperature of 30 ° C. Electrochemical roughening treatment was carried out in an amount and washed with water. Next, etching treatment was performed for 10 seconds at a caustic soda concentration of 30 g / l, an aluminum ion concentration of 10 g / l, and a liquid temperature of 40 ° C., and washed with running water. Next, desmut treatment was performed in a sulfuric acid aqueous solution having a sulfuric acid concentration of 15% by mass and a liquid temperature of 30 ° C., followed by washing with water. Furthermore, in a 10% by mass sulfuric acid aqueous solution at a liquid temperature of 20 ° C., an anodizing treatment was performed so that both of the anodized films corresponded to 2.5 g / m ² under a condition of a current density of 6 A / dm ² by direct current. , Dried. Then, it processed for 10 second at 30 degreeC with the sodium silicate 1.0 mass% aqueous solution, and produced the support body (a) which carried out the hydrophilic process.
When the center line average roughness (Ra) of the support (a) was measured using a needle having a diameter of 2 μm, it was 0.48 μm.

(Formation of undercoat layer)
On the support (a) thus obtained, an undercoat liquid having the following composition was applied and dried at 80 ° C. for 30 seconds to provide an undercoat layer. The dry coating amount of the undercoat layer was 17 mg / m ² .

<Undercoat liquid>
・ The following compound 0.3g

・ Methanol 100g
・ Water 1g

(Formation of recording layer)
A lower layer coating solution 1 having the following composition was applied to a support (a) having an undercoat layer with a bar coater so that the coating weight was 1.3 g / m ² and dried at 130 ° C. for 40 seconds. Cooled to ° C.

<Lower layer coating solution 1>
N-phenylmaleimide / methacrylic acid / methacrylamide copolymer (weight ratio: 59/15/25, Mw: 50,000) 3.44 g
・ Fluoroaliphatic group-containing copolymer (polymer 1 below) 1.80 g


Infrared absorber: 0.94 g of cyanine dye A having the following structure


・ Crystal Violet (Hodogaya Chemical Co., Ltd.) 0.08g
・ Methyl ethyl ketone 61.00g
・ Propylene glycol monomethyl ether 14.00g
・ Γ-butyrolactone 9.40 g
・ Water 9.34g

Further, on the lower layer, the upper layer coating solution 1 having the following composition was applied with a bar coater so that the coating weight was 0.5 g / m ² , dried at 135 ° C. for 40 seconds, and then slowly from 20 ° C. to 26 ° C. Until cooled.

<Upper layer coating solution 1>
・ Polyurethane synthesized by the following (1)
(25%, 3-pentanone solution) 30.00 g
Infrared absorber: 0.15 g of cyanine dye A having the above structure
・ Ethyl violet 0.03g
-Fluorosurfactant: Megafac F-176 (manufactured by DIC Corporation) 0.05 g
・ 3-Pentanone 62.40g
・ Propylene glycol monomethyl ether-2-acetate 7.37g

<< Synthesis of polyurethane (1) >>
In a 500 ml round bottom three-necked flask equipped with a concentrator and a stirrer, 2.7 g of 4,4′-diphenylmethane diisocyanate, 14.5 g of toluene-2,4-diisocyanate, 7.0 g of neopentyl glycol, 35.8 g of 2,2-bis (hydroxymethyl) propionic acid and 280 g of 3-pentanone were introduced. 0.3 g dibutyltin didodecanoate was added and the reaction mixture was heated to 80 ° C. with stirring. The reaction was continued at 80 ° C. for 6 hours. In this way, polyurethane (1) was obtained. The weight average molecular weight of the polyurethane (1) by GPC was 24,000. The acid value was 125.

  As described above, the planographic printing plate precursor of Example 1 was obtained.

[Examples 2-18, Comparative Examples 1-8]
In the same manner as in Example 1, except that the compositions of the lower layer coating solution 1 and the upper layer coating solution 1 used in Example 1 were changed to the compositions described in Table 1 or Table 2 below, Examples 2 to 2 were used. 18, lithographic printing plate precursors of Comparative Examples 1 to 8 were prepared.

  Polymers 1 to 14 shown in Tables 1 and 2 are the compounds listed above as specific examples of the fluoroaliphatic group-containing copolymer.

(Plate making and evaluation of planographic printing plate precursor)
Using the lithographic printing plate precursors of Examples 1 to 18 and Comparative Examples 1 to 8 obtained, the coated surface state, the development latitude, and the printing durability were evaluated. The evaluation results are shown in Table 3.

1. Evaluation of coated surface condition With respect to each lithographic printing plate precursor of Examples and Comparative Examples, the coated surface condition of the recording layer was visually observed. The surface evaluation was represented by the number of pinholes generated per square meter. The smaller the number of pinholes generated, the better the surface shape. The results are shown in Table 3 below.

2. Evaluation of development latitude The planographic printing plate precursors of Examples and Comparative Examples were exposed at a rate of 120 mJ / cm ^{2 using} a Trend setter manufactured by Creo. Thereafter, using a PS processor 940HII manufactured by Fujifilm Co., Ltd., which was charged with a developer XP-D (produced by Fujifilm Co., Ltd.) and developed to maintain the liquid temperature at 30 ° C. Developed in 12 seconds. About the obtained plate, the developability of the laser exposure area and the state of the image area were evaluated.
The development latitude is evaluated by the range of conductivity showing good image characteristics. A wider range is evaluated as being superior in development latitude. The optimum conductivity of the developer is at the center of the development latitude width.
The results are shown in Table 3 below.

3. Evaluation of printing durability The lithographic printing plate precursors of Examples and Comparative Examples were exposed at a rate of 120 mJ / cm ^{2 using} a Trend setter manufactured by Creo. Then, using Fujifilm Corporation PS processor 940HII charged with Fujifilm Corporation developer XP-D (diluted to a conductivity of 43 mS / cm), the liquid temperature was kept at 30 ° C., Developed with a development time of 12 seconds. The obtained plate was continuously printed using a printing press Lislon manufactured by Komori Corporation.
At this time, the number of sheets that can be printed while maintaining a sufficient ink density was measured visually to evaluate the printing durability. The larger the number, the better the printing durability.
The results are shown in Table 3 below.

  As shown in Table 3, the lithographic printing plate precursors of the examples have a wide development latitude and excellent printing durability in comparison with the lithographic printing plate precursors of the comparative examples. I understand that. It can also be seen that the planographic printing plate precursors of the examples are excellent in the coated surface state.

Claims (9)

  A recording layer provided by forming a lower layer and an upper layer in this order on a support having a hydrophilic surface, the lower layer being a water-insoluble and soluble or dispersible resin in an alkaline aqueous solution, and the lower layer And a fluoroaliphatic group-containing copolymer of 5% by mass to 50% by mass with respect to the total solid content of the polyurethane, wherein the upper layer is a water-insoluble and soluble or dispersible polyurethane in an alkaline aqueous solution. An infrared-sensitive positive lithographic printing plate precursor that is a layer containing a resin.   2. The infrared-sensitive positive electrode according to claim 1, wherein the fluoroaliphatic group-containing copolymer is a copolymer containing 5 mol% to 95 mol% of monomer units containing fluoroaliphatic groups in all monomer units. A lithographic printing plate precursor.   The infrared-sensitive positive lithographic printing plate precursor according to claim 1 or 2, wherein the fluoroaliphatic group-containing copolymer is a copolymer containing a monomer unit having an acidic group in a side chain.   The infrared-sensitive positive lithographic printing plate precursor according to claim 3, wherein the acidic group in the monomer unit having an acidic group in the side chain is a phenolic hydroxyl group, a sulfonamide group, or an active imide group.   The infrared-sensitive positive lithographic printing plate precursor according to any one of claims 1 to 4, wherein at least one of the lower layer and the upper layer contains an infrared absorber.   The lower layer was formed by applying and drying a coating liquid containing the water-insoluble and soluble or dispersible resin in an alkaline aqueous solution, the fluoroaliphatic group-containing copolymer, and a solvent on the support. The infrared-sensitive positive lithographic printing plate precursor according to any one of claims 1 to 5, which is a layer.   It is a manufacturing method of the infrared photosensitive positive planographic printing plate precursor of any one of Claims 1-6, Comprising: The coating liquid for lower layer formation and the coating liquid for upper layer formation are put on a support body in this order. A method for producing an infrared-sensitive positive lithographic printing plate precursor comprising a step of coating by sequential coating. An exposure step of exposing the infrared-sensitive positive lithographic printing plate precursor according to any one of claims 1 to 6 imagewise with infrared rays;
A method for producing a lithographic printing plate comprising, in this order, a development step of developing the positive lithographic printing plate precursor after exposure with an aqueous alkaline solution.   A lithographic printing plate obtained by the method for producing a lithographic printing plate according to claim 8.