JP5718176B2 - Method for preparing lithographic printing plate and treatment liquid composition - Google Patents

Description

  The present invention relates to a method for producing a lithographic printing plate, and a treatment liquid composition used in the production method, and more particularly to a method for producing a lithographic printing plate and a treatment liquid composition capable of simple processing that do not require a water washing step.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. The lithographic printing plate utilizes the property that water and printing ink repel each other, so that the oleophilic image area is used as the ink receiving area and the hydrophilic non-image area is used as the water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of the printing plate, and the ink is applied only to the image area, and then the ink is transferred to a printing medium such as paper for printing.
In order to produce this lithographic printing plate, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (also simply referred to as a recording layer) is provided on a hydrophilic support has been widely used. Yes. Normally, after exposing a lithographic printing plate precursor through an original image such as a lithographic film, the portion to be an image portion of the recording layer is left, and other unnecessary recording layers are removed with an alkaline developer or an organic solvent. The lithographic printing plate is obtained by dissolving and removing, and making a non-image part by exposing the surface of the hydrophilic support to form a non-image part.

  In recent years, digitization techniques for electronically processing, storing, and outputting image information by a computer have become widespread, and various new image output methods corresponding to such digitization techniques have come into practical use. It is coming. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with the light, and directly through the lithographic printing plate Computer-to-plate (CTP) technology has been attracting attention. Accordingly, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.

  Further, in the plate making process of a conventional lithographic printing plate precursor, after exposure, a process of dissolving and removing unnecessary recording layers with a developer or the like is necessary. However, in terms of environment and safety, the developer is closer to the neutral range. Treatment and low waste liquid are cited as issues. In particular, in recent years, the disposal of waste liquid discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and the demand for solving the above-mentioned problems has become stronger.

  As mentioned above, the low alkali level of the developer and the simplification of the processing process are more strongly desired than ever in terms of consideration for the global environment, space saving, and low running cost. It has become to. However, the conventional development processing step is a step of developing with a strong alkaline aqueous solution exceeding pH 11, a water washing step of removing the alkaline developer in a water washing bath, and then a step of processing with a gum solution containing a hydrophilic resin as a main component ( The automatic development machine itself takes up a lot of space and is also a problem in terms of environment and running costs, such as development waste, washing waste, and gum waste treatment. Is leaving.

On the other hand, for example, a developing method has been proposed in which processing is performed with a developer having an alkali metal carbonate and hydrogen carbonate having a pH of 8.5 to 11.5 and an electrical conductivity of 3 to 30 mS / cm (for example, patents). Reference 1). Although this method alleviates the problems caused by the high alkali agent, the water washing step and the gum solution treatment step after development are required, which leads to the solution of environmental and running cost issues such as a reduction in the amount of waste solution treatment. Not in.
In order to solve this problem, various attempts have been made to process development and gumming in one bath without the need for water washing after development. For example, a hydrophilic polymer having an amino group and an acid group was used. A processing method for a lithographic printing plate has been proposed in which a treatment solution composition is used to perform a one-bath treatment to develop the exposed portion recording layer and to hydrophilize the exposed support (for example, Patent Document 2). reference.)

JP-A-7-65126 Special table 2010-521423

However, in the processing method described in Patent Document 2, the durability of the hydrophilization treatment applied to the surface of the aluminum support in the non-image area is inferior, and therefore the non-image area is likely to become dirty as printing continues. There was a problem.
The object of the present invention, which has been made in consideration of the above problems, is that simple processing by a one-bath development processing step that does not require a water washing step is possible, and even when printing is continued, the printing durability of the image area is good. Another object of the present invention is to provide a method for preparing a lithographic printing plate in which a lithographic printing plate in which the occurrence of stains in the non-image area is prevented and a treatment liquid composition suitably used for the method.

As a result of investigations, the present inventors have found that the problem can be solved by using a polymer compound having a partial structure excellent in adhesion to the aluminum support in the developing solution composition, and the present invention has been completed. did. That is, the configuration of the present invention is as follows.
<1> An exposure step of exposing a positive photosensitive lithographic printing plate having an infrared sensitive positive recording layer on an aluminum support imagewise with an infrared laser;
The lithographic printing plate precursor after exposure, pH is from 5 to 10.7, a structural unit having a betaine structure in a side chain, a functional group capable of interacting with the aluminum support surface in a side chain, phosphorus An exposed portion region of the recording layer by contacting with an aqueous solution containing a water-soluble polymer compound comprising , as a constituent , a structural unit having one or more functional groups selected from an oxygen acid group and an onium group and removal of, a developing step of performing the hydrophilic treatment of the recording layer is exposed by removing the aluminum support surface, a method of preparing a lithographic printing plate having in this order.

<2 > The method for producing a lithographic printing plate according to < 1 >, wherein the phosphorus oxygen acid group is a phosphate ester group or a phosphonic acid group.
< 3 > The method for producing a lithographic printing plate according to <1> or < 2>, wherein the aqueous solution further contains carbonate ions and hydrogencarbonate ions.
< 4 > The method for preparing a lithographic printing plate according to any one of <1> to < 3 >, wherein the aqueous solution further contains 0.01% by mass to 20% by mass of a surfactant.
< 5 > The method for preparing a lithographic printing plate according to any one of <1> to < 4 >, wherein the development step is not followed by a water washing step.
< 6 > The method for preparing a lithographic printing plate according to any one of <1> to < 5 >, wherein the recording layer contains (A) an infrared absorber and (B) a water-insoluble and alkali-soluble resin.

< 7 > The recording layer is a recording layer having a multilayer structure composed of (C) a lower layer containing an alkali-soluble resin and (B) an upper layer containing a water-insoluble and alkali-soluble resin, and the upper layer and the lower layer The method for preparing a lithographic printing plate according to any one of <1> to < 6 >, wherein (A) an infrared absorber is contained in at least one layer of the above.
< 8 > One or more functional groups selected from a structural unit having a betaine structure in the side chain and a functional group that interacts with the aluminum support surface on the side chain , and an oxygen acid group and an onium group of phosphorus. And a water-soluble polymer compound containing water as a constituent component and water, and has a pH of 5 to 10.7 and has an infrared-sensitive positive recording layer on an aluminum support. The processing liquid composition used for the platemaking of a characteristic lithographic printing plate precursor.

  According to the present invention, simple processing by a one-bath development processing step that does not require a water washing step is possible, and even when printing is continued, the printing durability of the image portion is good, and contamination of the non-image portion is generated. A lithographic printing plate production method for producing a lithographic printing plate in which the above-mentioned is prevented and a treatment liquid composition suitably used for the production method are provided.

It is a schematic sectional drawing which shows the one aspect | mode of the structure of the automatic processor which can be used for the preparation method of the lithographic printing plate of this invention.

<Preparation method of lithographic printing plate>
The method for producing a lithographic printing plate according to the present invention comprises an exposure step of imagewise exposing a positive photosensitive lithographic printing plate having an infrared sensitive positive recording layer on an aluminum support with an infrared laser; The lithographic printing plate precursor includes a structural unit having a pH of 5 to 10.7 and having a betaine structure in the side chain and a structural unit having a functional group that interacts with the aluminum support surface in the side chain. A development step of contacting the aqueous solution containing the water-soluble polymer compound to remove the exposed area of the recording layer and to hydrophilize the surface of the aluminum support exposed by removing the recording layer. It is characterized by having in order. However, the functional group that interacts with the surface of the aluminum support is one or more functional groups selected from an oxygen acid group of phosphorus and an onium group.

The production method of the present invention is a production method for obtaining a lithographic printing plate by treating a lithographic printing plate precursor having a positive type recording layer, which does not require a water washing step, and uses a one bath treatment liquid composition. By the treatment, the development and removal treatment of the exposed area in the positive recording layer and the hydrophilic treatment of the surface of the aluminum support exposed by removing the recording layer in the exposure area can be easily performed in one step and obtained. The lithographic printing plate has good printing durability in the image area, and because the durability of the hydrophilic treatment of the support surface is good, the occurrence of stains is effectively suppressed even after printing many sheets, A large number of prints with excellent image quality can be obtained.
Further, usually, it is necessary to go through three steps of a development step, a water washing step, and a gumming step. According to the production method of the present invention, the development treatment is performed in one step for one bath and used. The composition also has a relatively low pH and can be easily treated, and the amount of waste liquid that requires treatment is significantly reduced compared to conventional production methods.

In the production method of the present invention, as a treatment liquid composition, a component having a functional group that interacts with the aluminum support surface on the side chain and a component having a betaine structure on the side chain in a relatively low pH alkaline aqueous solution It is one of the characteristics to use an aqueous solution containing a copolymer (hereinafter appropriately referred to as a specific water-soluble polymer compound).
Since the specific water-soluble polymer compound according to the present invention has a functional group that interacts (adsorbs) with the aluminum support surface and a betaine structure in the molecule, the unexposed portion recording layer is removed and exposed by development processing. When the surface of the aluminum support in the non-image area comes into contact with the treatment liquid composition, the specific water-soluble polymer compound is adsorbed on the surface of the support, and the hydrophilicity of the non-image area is improved. Further, since the adsorbed polymer compound is firmly adhered to the support surface, the hydrophilicity in the non-image area is maintained for a long time without being detached from the support surface of the non-image area even during printing.

<Treatment liquid composition>
First, an aqueous solution (hereinafter also referred to as a treatment liquid composition) used in the method for preparing a lithographic printing plate according to the present invention will be described. The treatment liquid composition of the present invention comprises a water-soluble polymer compound (specific water-soluble compound) comprising as structural components a structural unit having a betaine structure in the side chain and a structural unit having a functional group that interacts with the aluminum support surface in the side chain. A high molecular compound) and water, and an aqueous solution having a pH of 5 to 10.7.
Within the above pH range, both the removability of the recording layer in the exposed area and the printing durability of the image area are good.
The treatment liquid composition preferably further contains a surfactant (anionic, nonionic, cationic, zwitterionic, etc.).

(Specific water-soluble polymer compounds)
The specific water-soluble polymer compound contained in the treatment liquid composition of the present invention will be described.
The specific water-soluble polymer compound is a copolymer containing a structural unit having a betaine structure in the side chain and a structural unit having a functional group that interacts with the aluminum support surface in the side chain as a constituent component. It is a polymer compound.
In the present invention, “water-soluble” means that 0.5% by mass or more is dissolved in 25 ° C. water, and preferably 1% by mass or more is dissolved.

  The “functional group that interacts with the surface of the aluminum support” possessed by the specific water-soluble polymer compound according to the present invention includes a metal, metal oxide, hydroxyl group, etc. present on the aluminum support, a covalent bond, an ionic bond, hydrogen Examples thereof include functional groups capable of forming bonds or interactions such as bonds and polar interactions. Among these, a functional group that adsorbs to the surface of the aluminum support (hereinafter also referred to as an adsorptive group) is preferable. By having a predetermined amount of adsorptive groups in the molecule, the polymer compound has adsorptivity to the support surface.

Whether or not the specific water-soluble polymer compound is adsorbed on the support surface can be determined by the following method, for example.
A coating solution is prepared by dissolving a water-soluble polymer compound to be evaluated (hereinafter also referred to as a test compound) in a readily soluble solvent, and the coating amount after drying the coating solution is 30 mg / m ^2. It is coated on a support and dried. The substrate coated with the test compound is sufficiently washed with a readily soluble solvent, and then the residual amount of the test compound that has not been removed by washing is measured to calculate the amount of adsorption of the substrate. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The test compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, or liquid chromatography measurement.
In the present invention, the compound having support adsorptivity refers to a compound that remains at 0.1 mg / m ² or more after the washing treatment when the above evaluation is performed.

The adsorptive group on the surface of the aluminum support in the water-soluble polymer compound having a specific structure is a substance present on the surface of the aluminum support, for example, a functional group present on the surface of the aluminum support such as aluminum metal or aluminum metal oxide, For example, it refers to a functional group capable of forming a chemical bond or strong interaction with one selected from a hydroxyl group and the like, specifically, one or more functional groups selected from an oxygen acid group of phosphorus and an onium group Preferably, it is an oxygen acid group of phosphorus.
Examples of the oxygen acid group of phosphorus include a phosphate ester group, a phosphonic acid group, and a phosphinic acid group. Of these, a phosphate group and a phosphonic acid group are particularly preferable. These may form a salt, and examples of the salt include metal salts such as potassium salt and onium salts such as ammonium salt.
Examples of onium groups include ammonium groups (including cyclic ammonium groups such as pyridinium groups), phosphonium groups, sulfonium groups, and the like. Of these, an ammonium group is particularly preferable.

  As the adsorptive group, a phosphate ester group, a phosphonic acid group, and an onium group are preferable, and a phosphate ester group and a phosphonic acid group are most preferable.

  Hereinafter, preferred specific examples of the monomer having a functional group that interacts with the surface of the aluminum support, which is useful for producing the specific water-soluble polymer compound according to the present invention, are shown, but the present invention is not limited thereto. In the following structures, Me represents a methyl group, and Et represents an ethyl group.

The specific water-soluble polymer compound may have two or more types of structural units derived from the exemplified monomers and the like and having a functional group that interacts with the aluminum support surface.
The content ratio of the structural unit having a functional group that interacts with the surface of the aluminum support in the specific water-soluble polymer compound is preferably 2 mol% to 80 mol% with respect to all the structural units contained in the specific water-soluble polymer compound. 2 mol%-70 mol% are more preferable, 5 mol%-50 mol% are further more preferable, and 10 mol%-50 mol% are especially preferable.

The specific water-soluble polymer compound according to the present invention has a structural unit having a betaine structure in the side chain as a constituent component. In the polymer compound, the betaine structure functions as a hydrophilic group.
The betaine structure in the present invention refers to a structure having both a cation structure and an anion structure in one group, and the charge is neutralized. The cation structure in the betaine structure is not particularly limited, but a quaternary nitrogen cation is preferable.
The anionic structure in the betaine structure is not particularly ^limited, -COO ^_-, -SO 3 - is preferably a structure selected from, -COO ^{- -,} _-PO ^{3 2-and} _-PO 3 H or - More preferably, it is SO ₃ ^— .
Examples of the betaine structure include structures represented by the following formula (B1) or formula (B2).

In formula (B1) and formula (B2), R ¹¹ _, R ¹² _, R ¹⁴ and R ¹⁵ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms. R ¹³ and R ¹⁶ each independently represent a divalent organic group, and examples of the second section organic group include a divalent aliphatic group, a divalent aromatic group, or a combination of two or more thereof. A bivalent coupling group etc. are mentioned.

  Specific examples of the structural unit having a betaine structure that can be included in the specific water-soluble polymer compound according to the present invention are shown below.

The water-soluble polymer compound having a specific structure may have only one type of component having a betaine structure in the side chain, or may have two or more types.
The content ratio of the component having a betaine structure in the side chain in the water-soluble polymer compound having a specific structure is preferably 30 mol% to 98 mol% with respect to all components having the water-soluble polymer compound having the specific structure, 40 mol%-90 mol% are more preferable, and 50 mol%-90 mol% are still more preferable.

In the specific water-soluble polymer compound according to the present invention, the functional group that interacts with the aluminum support surface is adsorbed on the exposed aluminum support surface in the non-image area during development, while the betaine structure is adsorbed. In order to impart high hydrophilicity to the specific water-soluble polymer compound, it is considered that it contributes to the prevention of soiling of non-image areas and its durability.
The specific water-soluble polymer compound used in the treatment liquid composition of the present invention is a structural unit other than the structural unit having a functional group that interacts with the surface of the aluminum support and the structural unit having a betaine structure (hereinafter referred to as another structure). May be included depending on the purpose as long as the performance of the present invention is not impaired.
There is no restriction | limiting in particular in another structural unit, What is necessary is just a structural unit derived from a well-known monomer. Examples of other structural units include structural units derived from (meth) acrylic acid esters and (meth) acrylic acid amides.
When the specific water-soluble polymer compound contains other structural units, the content ratio of the other structural units is preferably 40 mol% or less, more preferably 30 mol% with respect to the structural units of the specific water-soluble polymer compound. Preferably, 20 mol% or less is more preferable.

  The specific water-soluble polymer compound used in the treatment liquid composition of the present invention is a vinyl copolymer. That is, the structural unit contained as a constituent component in the specific water-soluble polymer compound includes, for example, acrylates, methacrylates, styrenes, aromatic vinyl compounds, aliphatic vinyl compounds, allyl compounds, acrylic acid, methacrylic acid, and the like. It is a structural unit derived from a monomer having such an ethylenically unsaturated bond.

The weight average molecular weight of the specific water-soluble polymer compound is preferably 5,000 or more, more preferably 10,000 or more, more preferably 1,000,000 or less, and more preferably 500,000 or less.
The number average molecular weight of the specific water-soluble polymer compound is preferably 1,000 or more, more preferably 2,000 or more, preferably 500,000 or less, and more preferably 300,000 or less.
By setting the molecular weight within this range, the hydrophilicity and durability of the non-image area are further improved.

  Specific examples of the specific water-soluble polymer compound that can be suitably used in the present invention are illustrated below, but the present invention is not limited thereto.

The treatment liquid composition of the present invention may contain two or more of the specific water-soluble polymer compounds.
The content of the specific water-soluble polymer compound in the treatment liquid composition of the present invention is preferably 0.1% by mass to 20% by mass, more preferably 0.5% by mass to 10% by mass, and 2% by mass to 10% by mass. % Is more preferable. Within the above range, a good non-image area stain prevention effect can be obtained.

(PH of treatment liquid composition)
The treatment liquid composition of the present invention requires a pH of 5 to 10.7, but is preferably in the range of 6 to 10.5, particularly preferably in the range of 6.8 to 9.9.
Although the method of adjusting the pH of the treatment liquid composition of the present invention to the range of 5 to 10.7 is arbitrary, in general, by adding an alkali agent or using a pH buffer, May be adjusted within the above range.

(Alkaline agent)
Examples of the alkali agent used to adjust the pH of the treatment liquid composition include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, and hydrogen carbonate. Ammonium is mentioned, and these may be used in combination of two or more. In addition, as acid used with an alkali agent for pH adjustment, inorganic acids, for example, hydrochloric acid, sulfuric acid, nitric acid, etc. can be used.
The pH adjustment is preferably performed by one or more alkali agents selected from, for example, sodium hydroxide, potassium hydroxide, and sodium carbonate, or a combination of these alkali agents and hydrochloric acid.

(PH buffer)
In the present invention, the pH buffer used for adjusting the pH of the treatment liquid composition can be used without particular limitation as long as it is a buffer that exhibits a buffering action in the range of pH 5 to 10.7.
In the present invention, weakly alkaline buffering agents are preferably used. For example, (a) carbonate ions and hydrogen carbonate ions, (b) borate ions, (c) water-soluble amine compounds and ions of the amine compounds, and their Combination use etc. are mentioned. That is, for example, a combination of (a) carbonate ion-bicarbonate ion, (b) borate ion, or (c) water-soluble amine compound-amine compound ion is preferably used.
The pH buffering agent exhibits a pH buffering effect in the processing liquid composition, and can suppress fluctuations in pH even when the processing liquid composition is used for a long period of time, and can suppress deterioration in developability due to fluctuations in pH, generation of development residue, etc. . In the present invention, a combination of carbonate ion and hydrogen carbonate ion is particularly preferable.

(A) Carbonate ion and hydrogen carbonate ion In order to make carbonate ion and hydrogen carbonate ion exist in the treatment liquid composition, carbonate and hydrogen carbonate may be added to the treatment liquid composition, or carbonate or hydrogen carbonate. Carbonate ions and bicarbonate ions may be generated by adjusting the pH after adding the salt. The carbonate and bicarbonate are preferably alkali metal salts. Examples of the alkali metal include lithium, sodium, and potassium, and sodium is particularly preferable. Two or more alkali metals may be used in combination.

  The total amount of carbonate ions and bicarbonate ions is preferably 0.05 mol / L to 5 mol / L, more preferably 0.07 mol / L to 2 mol / L, and more preferably 0.1 mol / L to 1 mol / L with respect to the treatment liquid composition. L is particularly preferred.

(B) Boric acid ions As a method of making boric acid ions exist in the treatment liquid composition, an appropriate amount of boric acid ions can be obtained by adjusting pH after adding boric acid or borate to the treatment liquid composition. The method of generating is mentioned. The boric acid or borate used here is not particularly limited, and examples of boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Among them, orthoboric acid and tetraboric acid are preferable. Examples of borates include alkali metal salts or alkaline earth metal salts, such as orthoborate, diborate, metaborate, tetraborate, pentaborate, and octaborate. Of these, orthoborate and tetraborate are preferable, and alkali metal tetraborate is particularly preferable. Preferred examples of the tetraborate include sodium tetraborate, potassium tetraborate, and lithium tetraborate. Among them, sodium tetraborate is preferable.
As the boric acid or borate used in the present invention, orthoboric acid, tetraboric acid or sodium tetraborate is particularly preferable.
Two or more types of boric acid or borate contained in the treatment liquid composition may be used in combination, or boric acid and borate may be used in combination.
The total amount of borate in the developer is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, and particularly preferably 1 to 12% by mass with respect to the total mass of the developer.

(C) Water-soluble amine compound and ion of the amine compound In the present invention, a combination of a water-soluble amine compound and an ion of the amine compound can also be preferably used.
The water-soluble amine compound is not particularly limited, but a water-soluble amine having a group that promotes water solubility is preferable. Examples of groups that promote water solubility include carboxylic acid groups, sulfonic acid groups, sulfinic acid groups, phosphonic acid groups, and hydroxyl groups. Of these, amine compounds having a hydroxyl group are particularly preferred.

  As the water-soluble amine compound having a hydroxyl group, monoethanolamine, diethanolamine, triethanolamine, and N-hydroxyethylmorpholine are preferable.

  The total amount of the water-soluble amine compound and the salt of the amine compound is preferably 0.5% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and more preferably 1% by mass with respect to the mass of the treatment liquid composition. ˜12% by weight is particularly preferred.

(Other ingredients)
The treatment liquid composition of the present invention is an aqueous solution having a pH of 5 to 10.7 containing the specific water-soluble polymer compound and water. However, depending on the purpose, in addition to the above components, the effect of the present invention is not impaired. Further, it may contain a known additive used for a known developer and replenisher.
(Surfactant)
The treatment liquid composition of the present invention preferably contains a surfactant in addition to the specific water-soluble polymer compound. As the surfactant, any of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant can be preferably used.
As the anionic surfactant, alkylbenzene sulfonates, alkylnaphthalene sulfonates, and alkyl diphenyl ether (di) sulfonates are particularly preferably used.
Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, alkylimidazolinium salts, polyoxyethylene alkylamine salts, polyethylene polyamine derivatives, and the like. As the nonionic surfactant, those having an aromatic ring and an ethylene oxide chain are preferable, and an alkyl-substituted or unsubstituted phenol ethylene oxide adduct or an alkyl-substituted or unsubstituted naphthol ethylene oxide adduct is more preferable.
Examples of zwitterionic surfactants include amine oxides such as alkyldimethylamine oxide, betaines such as alkylbetaines, and amino acid systems such as sodium alkylamino fatty acids.
In particular, alkyldimethylamine oxide, alkylcarboxybetaine, and alkylsulfobetaine are preferably used.

  In the case where the treatment liquid composition contains a surfactant, the content of the surfactant is preferably 0.01% by mass to 20% by mass, and more preferably 0.1 to 10% by mass. Two or more surfactants may be used.

(Film-forming water-soluble polymer compounds: other water-soluble polymer compounds)
The treatment liquid composition of the present invention is a water-soluble polymer compound having a film-forming property having a structure different from that of the specific water-soluble polymer compound in order to protect the plate surface and suppress scratches on the plate surface (hereinafter referred to as other It is also preferable to further contain a water-soluble polymer compound).
Examples of other water-soluble polymer compounds include gum arabic, fiber derivatives (eg, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, hydroxypropylcellulose, methylpropylcellulose, etc.) and modified products thereof, polyvinyl alcohol and derivatives thereof, polyvinyl Pyrrolidone, polyacrylamide, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, styrene / maleic anhydride copolymer, starch derivatives (eg, dextrin, maltodextrin, enzymatically degraded dextrin, hydroxy Propylated starch, hydroxypropylated starch enzymatically degraded dextrin, carboxydimethylated starch, phosphorylated starch, cyclodextrin), pullulan and pullulan derivatives .
Among them, gum arabic, starch derivatives such as dextrin and hydroxypropyl starch, carboxymethyl cellulose, soybean polysaccharide and the like can be preferably used.
When the treatment liquid composition of the present invention contains another water-soluble polymer compound, the content of the other water-soluble polymer compound is preferably in the range of 0.05% by mass to 15% by mass. More preferably, it is in the range of 5% by mass to 10% by mass.

(Organic solvent)
The treatment liquid composition of the present invention may contain an organic solvent. Examples of the organic solvent that can be contained include aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and polar solvents. Examples of polar solvents include alcohols, ketones, esters, and others (triethyl phosphate, tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, 4- ( 2-hydroxyethyl) morpholine, N, N-dimethylacetamide, N-methylpyrrolidone and the like.

  Two or more organic solvents can be used in combination in the treatment liquid composition. When the organic solvent is insoluble in water, it can be used after being solubilized in water using a surfactant or the like. From the viewpoint of safety and flammability, the concentration of the organic solvent is preferably less than 40% by mass, preferably less than 10% by mass, and more preferably less than 5% by mass.

  In addition to the above components, the treatment liquid composition may contain preservatives, chelate compounds, antifoaming agents, organic acids, inorganic acids, inorganic salts, and the like. Specifically, compounds described in paragraph numbers [0266] to [0270] of JP-A-2007-206217 can be preferably used.

The processing liquid composition of the present invention is used for developing and hydrophilizing the exposed positive planographic printing plate precursor, and may be used in the same manner as a normal developing solution, and as a development replenisher as necessary. It can also be used.
The processing liquid composition of the present invention can be preferably applied to an automatic developing processor. When used in an automatic developing processor, it may be used in the same manner as a known developer. When developing using an automatic developing processor, the developing solution becomes fatigued according to the amount of processing, so the replenishing solution or fresh developing solution may be used to restore the processing capability, and at this time, it is added The processing liquid composition of the present invention may be used in place of the replenisher or developer.

Next, a positive photosensitive lithographic printing plate used in a method for preparing a lithographic printing plate will be described.
[Positive photosensitive lithographic printing plate precursor]
The positive photosensitive lithographic printing plate precursor according to the present invention has an infrared sensitive (hereinafter sometimes simply referred to as photosensitive) positive recording layer on an aluminum support. The lithographic printing plate precursor may have a layer other than the positive recording layer, for example, a protective layer, an undercoat layer and the like.
Hereinafter, the positive photosensitive lithographic printing plate precursor used in the method for preparing a lithographic printing plate according to the present invention will be described.

[Infrared sensitive positive recording layer]
As the positive recording layer of the lithographic printing plate precursor according to the present invention, a known positive recording layer, for example, a polarity conversion material system (change from hydrophobic to hydrophilic), an acid catalyst decomposition system, an interaction release system (heat sensitive) Any of the positive) recording layers can be used, but from the viewpoint of stability and sensitivity, it contains at least (A) an infrared absorber and (B) a water-insoluble and alkali-soluble resin, and dissolves in the developer in the exposed area. An interaction release type recording layer that improves the properties is preferable.
The recording layer may have a single layer structure or a multilayer structure. However, in consideration of image forming properties such as development latitude, a recording layer having a multilayer structure is preferable.
The recording layer having a multilayer structure is a multilayer structure comprising (C) a lower layer containing an alkali-soluble resin, and (B) an upper layer containing a water-insoluble and alkali-soluble resin, and includes at least one of the upper layer and the lower layer. A structure containing (A) an infrared absorber in one layer is preferable, and (A) an infrared absorber, (C-1) an alkali-soluble acrylic resin, and (C-2) a phenol resin are contained in the lower layer, and an upper layer (B-1) An embodiment containing a water-insoluble and alkali-soluble polyurethane resin is more preferable. Here, (B-1) the water-insoluble and alkali-soluble polyurethane resin is preferably a polyurethane resin having a carboxy group in the polymer main chain.

Hereinafter, each component contained in the positive recording layer will be described.
The interaction release positive recording layer, which is an infrared sensitive positive recording layer according to the present invention, includes a compound (A) having dissolution inhibiting ability represented by an infrared absorber as shown below and a known (B) The recording layer is composed of a water-insoluble and alkali-soluble resin, and has an alkali developability due to the interaction between the alkali-soluble resin and a compound having a dissolution inhibiting function. By releasing the interaction in the infrared laser irradiation area of the positive recording layer, the exposed area develops solubility in alkali developability to form an image.

((A) infrared absorber)
There is no particular limitation on the infrared absorber contained in the positive recording layer of the lithographic printing plate precursor, and various dyes or pigments known as infrared absorbers can be appropriately selected and used.
The positive recording layer contains an infrared absorber. When the recording layer has a multi-layer structure, the infrared absorber may be included in the upper layer, the lower layer, or both the upper layer and the lower layer.

  As the infrared absorber according to the present invention, known ones can be used, for example, azo dyes, metal complex azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes and the like. Dyes. In the present invention, among these dyes, those which absorb infrared light or near infrared light can be suitably used for recording with a laser emitting infrared light or near infrared light.

  Examples of such dyes that absorb infrared light or near infrared light include, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, and JP-A-60-. Cyanine dyes described in JP-A-78787, methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, etc., JP-A-58-112793 Naphthoquinone dyes described in JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc. Examples thereof include squarylium dyes described in Japanese Utility Model Laid-Open No. 58-112792, and cyanine dyes described in British Patent 434,875.

Moreover, as a dye as an infrared absorber, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used. Further, substituted arylbenzo (thio) pyrylium salts described in US Pat. No. 3,881,924, trimethine thiapyrylium salts described in JP-A-57-142645 (US Pat. No. 4,327,169), The pyrylium system described in JP-A-58-181051, 58-220143, 59-41363, 59-84248, 59-84249, 59-146063, 59-146061 Compounds, cyanine dyes described in JP-A-59-216146, pentamethine thiopyrylium salts described in U.S. Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. And pyrylium compounds. Moreover, as a commercial item of the infrared absorber which can be used for this invention, Epolight III-178, Epolight III-130, Epolight III-125, etc. by Eporin are mentioned as a particularly preferable thing.
Another particularly preferable example of the dye includes near infrared absorbing dyes described as the formulas (I) and (II) in US Pat. No. 4,756,993.

  Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Furthermore, the cyanine dye represented by the following general formula (a) is most preferable because it gives high polymerization activity and is excellent in stability and economy when used in the lower layer in the present invention.

In general formula (a), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group shown below. X ² represents an oxygen atom or a sulfur atom. L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a hydrocarbon group having 1 to 12 carbon atoms including a hetero atom. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se.

In the above formula, Xa ^- has Za described later ^- has the same definition as, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom.

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

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned.
Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups.
R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Furthermore, Za ^- represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (a) has an anionic substituent in its structure and charge neutralization is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a hexagonal salt, in view of the storage stability of the recording layer coating solution. Fluorophosphate ion and aryl sulfonate ion.

Specific examples of the cyanine dye represented by the general formula (a) that can be suitably used include paragraph numbers [0017] to [0019] of JP-A No. 2001-133969 and paragraph numbers of JP-A No. 2002-40638. [0012] to [0038] and paragraphs [0012] to [0023] described in JP-A No. 2002-23360.
Particularly preferred as the infrared absorber contained in the lower layer is a cyanine dye shown below.

The recording layer contains an infrared absorber to increase sensitivity.
(A) As the addition amount of the infrared absorber, from the viewpoint of sensitivity, recording layer uniformity and durability, it can be added at a ratio of 0.01 to 50% by mass with respect to the total solid content of the lower layer. It is preferable that it is the range of 1-30 mass%, Most preferably, it is the range of 1.0-30 mass%.

[(B) Water-insoluble and alkali-soluble resin]
Examples of water-insoluble and alkali-soluble resins that can be used in the positive recording layer (hereinafter, appropriately referred to as alkali-soluble resins) include homopolymers containing acidic groups in the main chain and / or side chain in the polymer, Or a mixture thereof.
Among these, those having an acidic group listed in the following (1) to (6) in the main chain and / or side chain of the polymer are preferable from the viewpoint of solubility in an alkaline developer and expression of dissolution inhibiting ability.

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

  In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrogen atom or a hydrocarbon group which may have a substituent. .

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

For example, an alkali-soluble novolak resin is suitable as the alkali-soluble resin having a phenol group (hereinafter also referred to as a phenol resin) preferably used in the present invention. Examples of the alkali-soluble novolak resin include phenol formaldehyde novolak resin, m-cresol formaldehyde novolak resin, p-cresol formaldehyde novolak resin, m- / p-mixed cresol formaldehyde novolak resin, phenol / cresol (m-, p-, m Any of-/ p- may be used) Alkali-soluble novolak resins such as mixed formaldehyde novolak resins may be mentioned.
As these alkali-soluble novolak resins, those having a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000 are preferably used.

  Further, as described in U.S. Pat. No. 4,123,279, the phenol resin has an alkyl group having 3 to 8 carbon atoms as a substituent such as t-butylphenol formaldehyde novolak resin and octylphenol formaldehyde novolak resin. You may use together the condensate of the phenol and formaldehyde which have.

The phenol resin contained in the recording layer may be a resole resin.
The resol resin used in the present invention is a resin obtained by condensing phenols and aldehydes under basic conditions.
As the above-mentioned phenols, for example, phenol, m-cresol, p-cresol, o-cresol, bisphenol A and the like are preferably used. Examples of the aldehydes include formaldehyde. The said phenols and aldehydes can be used individually or in combination of 2 or more types.
Further, it may be a resol resin obtained from a mixture of phenols described above and formaldehyde. In obtaining the resol resin, the degree of condensation between the phenol and formaldehyde, the molecular weight, the residual ratio of the residual monomer, etc. may be selected according to the purpose.

  (2) As an alkali-soluble resin having a sulfonamide group, for example, a polymer composed of a minimum constituent unit derived from a compound having a sulfonamide group as a main constituent can be mentioned. Examples of the compound as described above include compounds having at least one sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom and one or more polymerizable unsaturated groups in the molecule. Among these, low molecular weight compounds having an acryloyl group, an allyl group, or a vinyloxy group, and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group in the molecule are preferable. For example, the following general formula (i) to general formula The compound represented by (v) is mentioned.

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

  Among the compounds represented by the general formula (i) to the general formula (v), in the positive lithographic printing material of the present invention, in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide N- (p-aminosulfonylphenyl) acrylamide and the like can be preferably used.

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

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

As the (B) alkali-soluble resin, (B-1) a water-insoluble and alkali-soluble polyurethane resin is also preferably used.
((B-1) Water-insoluble and alkali-soluble polyurethane resin)
The water-insoluble and alkali-soluble polyurethane resin preferably has a carboxyl group in the polymer main chain. Specifically, the diisocyanate compound represented by the following general formula (I) and the following general formula (II) or general A polyurethane resin having a basic skeleton as a reaction product with a diol compound having a carboxyl group represented by the formula (III) can be mentioned.

In the general formula (I), R ¹ represents a divalent hydrocarbon group, preferably an alkylene group having 2 to 10 carbon atoms or an arylene group having 6 to 30 carbon atoms. R ¹ may have another functional group that does not react with the isocyanate group.
In general formula (II), R ² represents a hydrogen atom or a hydrocarbon group, 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. Groups.
In general formula (II) and general formula (III), R ³ , R ⁴ and R ⁵ each independently represent a single bond or a divalent linking group. Examples of the divalent linking group include an aliphatic hydrocarbon group and an aromatic hydrocarbon group, and preferably an unsubstituted alkylene group having 1 to 20 carbon atoms and an unsubstituted hydrocarbon group having 6 to 15 carbon atoms. A substituted arylene group is mentioned, More preferably, a C1-C8 unsubstituted alkylene group is mentioned.
In general formula (III), Ar represents a trivalent aromatic hydrocarbon, and preferably represents an arylene group having 6 to 15 carbon atoms.
R ^{1 to} R ⁵ and Ar may each have a substituent that does not react with the isocyanate group.

Specific examples of the diisocyanate compound represented by the general formula (I) include the following, but are 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) Nate methyl) cycloaliphatic diisocyanate compounds such as cyclohexane; and 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.

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 are 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 and the like.
Of these, 2,2-bis (hydroxymethyl) propionic acid and 2,2-bis (hydroxyethyl) propionic acid are preferred from the viewpoint of reactivity with isocyanate.

  Furthermore, as the diol compound for obtaining the water-insoluble and alkali-soluble polyurethane resin according to the present invention, from the viewpoint of improving the solubility in the developer and the permeability of the developer in the recording layer, the following general formula (IV) It is desirable to use a diol compound represented by

  In general formula (IV), n represents the integer of 4-12, Preferably it is an integer of 6-10.

  The polyurethane resin according to the present invention can be synthesized by adding the above-mentioned diisocyanate compound and diol compound to an aprotic solvent by adding a known catalyst having activity corresponding to the reactivity and heating.

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.
(B-1) The water-insoluble and alkali-soluble polyurethane resin is preferably a polyurethane resin having a carboxy group in the polymer main chain.
The molecular weight of the water-insoluble alkali-soluble polyurethane resin according to the present invention is preferably 1,000 or more in weight average, and more preferably in the range of 5,000 to 100,000. These polyurethane resins may be used in combination of two or more.

The positive recording layer may contain only one (B) water-insoluble and alkali-soluble resin, or may contain two or more.
(B) The water-insoluble and alkali-soluble resin is preferably 30% by weight to 98% by weight and more preferably 40% by weight to 95% by weight in the total solid content of the positive recording layer. When the content is in the above range, the durability and sensitivity of the recording layer and the image formability are maintained well.

(C) Alkali-soluble resin The positive recording layer may contain an alkali-soluble resin having water solubility. The alkali-soluble resin is not particularly limited as long as it is soluble in an alkaline aqueous solution, and (B) water-insoluble and alkali-soluble resins mentioned above and water-soluble and alkali-soluble resins can be used.

((C-1) alkali-soluble acrylic resin)
An alkali-soluble acrylic resin may be used as the alkali-soluble resin.
Suitable alkali-soluble acrylic resins include resins having an acidic group as described above in the main chain or side chain in the polymer. Such a resin is obtained, for example, by polymerizing a monomer mixture containing at least one ethylenically unsaturated monomer having an acidic group. Examples of the ethylenically unsaturated monomer having an acidic group useful for forming the alkali-soluble resin include monomers represented by the following formula in addition to acrylic acid and methacrylic acid, and ethylene having these acidic groups. The unsaturated monomer may be used as a mixture of not only one type but also two or more types.

In the above formulas, R ¹ independently represents a hydrogen atom or a methyl group.

  The alkali-soluble acrylic resin is preferably a polymer compound obtained by copolymerizing the ethylenically unsaturated monomer (polymerizable monomer) having the acidic group and another polymerizable monomer. The copolymerization ratio in this case is preferably 10 mol% or more, preferably 20 mol% or more and 80 mol% or less of a polymerizable monomer having an acidic group for imparting alkali solubility from the viewpoint of developability of the recording layer. More preferably, it is contained at a ratio of

(C-1) Phenol Resin As the (C) alkali-soluble resin, the phenol resin described above in the section of (B) water-insoluble and alkali-soluble resin is also useful.

  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. More preferred alkali-soluble acrylic resins have a weight average molecular weight of 5,000 to 300,000, a number average molecular weight of 800 to 250,000 and a dispersity (weight average molecular weight / number average molecular weight) of 1. 1-10.

  The weight average molecular weight of the alkali-soluble resin used was a value calculated by GPC (gel permeation chromatography) measurement in terms of the molecular weight of a polystyrene sample. Moreover, the value measured similarly was used also about the weight average molecular weight of the other high molecular compound in this specification.

When the recording layer has a multi-layer structure, it is preferable to have a lower layer excellent in alkali solubility and an upper layer excellent in image forming property. From such a viewpoint, (C) a lower layer containing an alkali-soluble resin, and (B And a multilayer structure comprising an upper layer containing a water-insoluble and alkali-soluble resin, wherein (A) an infrared absorber is preferred in at least one of the upper layer and the lower layer, and (A) an infrared absorber. Is more preferably included in the upper layer.
In another preferred embodiment, the lower layer contains (A) an infrared absorber, (C-1) an alkali-soluble acrylic resin, and (C-2) a phenol resin, and the upper layer contains (B-1) water-insoluble and The aspect of the multilayer structure containing an alkali-soluble polyurethane resin is mentioned.
At this time, the content of the (C-1) alkali-soluble acrylic resin is preferably 20 to 98% by mass, more preferably 30 to 95%, based on the total solid content of the lower layer, from the viewpoint of both sensitivity and durability of the recording layer. % By mass. Moreover, 2-80 mass% is preferable in the total solid of a lower layer, and, as for content of (C-2) phenol resin, More preferably, it is 5-75 mass%.
If a resol resin is used as the phenolic resin, the content thereof is preferably 2 to 80% by mass in the total solid content of the lower layer, more preferably from the viewpoint of the durability and storage stability of the recording layer. Is 5 to 75% by mass, particularly preferably 10 to 70% by mass.

The content ratio (C-1: C-2) of (C-1) alkali-soluble acrylic resin and (C-2) phenol resin in the lower layer is preferably 98: 2 to 20:80 on a mass basis, 95 : 5 to 25:75 is more preferable, and 90:10 to 30:70 is more preferable.
Furthermore, the content of the (B-1) water-insoluble and alkali-soluble polyurethane resin contained in the upper layer is preferably 2 to 99.5% by mass, more preferably 5 to 99% by mass in the total solid content of the upper layer. Especially preferably, it is 10-98 mass%.

(Other ingredients)
In addition to the above essential components, various additives can be added to the upper layer or the lower layer of the recording layer according to the present invention 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 layers.

<< Development accelerator >>
In the upper layer or the lower layer of the recording layer according to the present invention, acid anhydrides, phenols, and organic acids may be added for the purpose of accelerating development in the exposed area and improving sensitivity.
As the acid anhydrides, cyclic acid anhydrides are preferable. Specific examples of the cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride described in US Pat. No. 4,115,128. Acid, 3,6-endooxy-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Examples of the acyclic acid anhydride 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 organic acids include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, 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-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 layer or upper layer is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, and particularly preferably 0.8. 1 to 10% by mass.

<< Surfactant >>
At least one of the upper and lower layers as the recording layer according to the present invention is disclosed in Japanese Patent Application Laid-Open No. 62-251740 and Japanese Patent Application Laid-Open No. 62-251740 in order to improve the coating property and to increase the stability of processing with respect to the development conditions. Nonionic surfactants as described in JP-A-3-208514, amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, JP-A-62 -170950, JP-A-11-288093, JP-A-2004-12770, and the like can be incorporated.

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 Co., Ltd.).
The proportion of the surfactant in the total solid content of the lower layer or upper layer is preferably 0.01 to 15% by mass, more preferably 0.1 to 5% by mass, and still more preferably 0.05 to 2.0% by mass. It is.

<< Bakeout agent / Colorant >>
A print-out agent for obtaining a visible image immediately after heating by exposure and a dye or pigment as an image colorant can be added to at least one of the upper layer and the lower layer of the recording layer according to the present invention.
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. Specifically, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A-50-36209 and JP-A-53-8128, 36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440, and trihalomethyl compounds and salt-forming organic dyes Can be mentioned. Such trihalomethyl compounds include oxazole-based compounds and triazine-based compounds, both of which have excellent temporal stability and give clear printout images.

As the image colorant, other dyes can be used in addition to the aforementioned salt-forming organic dyes. Examples of suitable dyes including salt-forming organic dyes include oil-soluble dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (oriental chemical industry) 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), and the like. it can. The dyes described in JP-A-62-293247 are particularly preferred.
These dyes can be added in a proportion of 0.01% by mass to 10% by mass, preferably 0.1% by mass to 3% by mass, based on the total solid content of the lower layer or the upper layer.

<< Plasticizer >>
A plasticizer may be added to at least one of the upper layer and the lower layer, which are recording layers according to the present invention, in order to impart flexibility of the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid These oligomers and polymers are used.
These plasticizers can be added in a proportion of 0.5% by mass to 10% by mass, preferably 1.0% by mass to 5% by mass, based on the total solid content of the lower layer or the upper layer.

<< WAX agent >>
A WAX agent may be added to the upper layer according to the present invention as a compound for reducing the static friction coefficient of the surface for the purpose of imparting scratch resistance. Specifically, US Pat. No. 6,117,913 or Japanese Patent Laid-Open Nos. 2003-149799, 2003-302750, and 2004-12770 previously proposed by the applicant of the present application. And a compound having an ester of a long-chain alkylcarboxylic acid as described in 1).
The amount of the WAX agent added is preferably 0.1% by mass to 10% by mass, more preferably 0.5% by mass to 5% by mass, in terms of solid content, in the upper layer.

  As other components, in addition to the above-mentioned components, for example, an onium salt, an o-quinonediazide compound, an aromatic sulfone compound, an aromatic sulfonic acid ester compound and the like are thermally decomposable, and in an undecomposed state, an alkaline aqueous solution-soluble resin The substance which substantially reduces the solubility of is mentioned. By using the additive, it is possible to improve the dissolution inhibition property of the image portion in the developer.

-Formation of recording layer-
The recording layer is formed by applying and drying a recording layer coating solution prepared by dissolving each of the above components in a solvent on a support described later. When forming a multi-layered recording layer having an upper layer and a lower layer, the formation of each layer may be sequential or simultaneous.

  Solvents used for adjusting the coating solution for forming the upper layer and lower layer include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1- Methoxy-2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, toluene, etc. However, the present invention is not limited to this. These solvents are used alone or in combination.

In principle, the lower layer and the upper layer are preferably formed by separating two layers.
As a method for forming the two layers separately, for example, a method using a difference in solvent solubility between a component contained in the lower layer and a component contained in the upper layer, or after applying the upper layer, a solvent is rapidly used. For example, a method of drying and removing.
Hereinafter, although these methods are explained in full detail, the method of isolate | separating and apply | coating two layers is not limited to these.

  As a method of utilizing the difference in solvent solubility between the component contained in the lower layer and the component contained in the upper layer, a solvent system in which any of the components contained in the lower layer is insoluble is used when the upper layer coating solution is applied. Is. Thereby, in two-layer coating, it becomes possible to separate each layer clearly into a coating film. For example, as the lower layer component, a component insoluble in a solvent such as methyl ethyl ketone or 1-methoxy-2-propanol that dissolves the alkali-soluble resin that is the upper layer component is selected, and the lower layer is applied using a solvent system that dissolves the lower layer component. -It is possible to form the upper layer and the lower layer separately by drying and then dissolving the upper layer mainly composed of alkali-soluble resin with methyl ethyl ketone or 1-methoxy-2-propanol, and applying and drying. .

  Further, as another means for forming the upper layer and the lower layer separately, there is a method of drying the solvent very quickly after applying the second layer (upper layer). In this method, in the coating step, after the upper layer coating, a step of blowing high-pressure air from a slit nozzle installed substantially perpendicular to the traveling direction of the support (web), a roll supplied with a heating medium such as steam inside What is necessary is just to carry out the process of giving thermal energy as conduction heat from the lower surface of the support from the (heating roll) or a combination of the above processes. This method is a method of suppressing dissolution of the lower layer by the upper layer coating solvent by rapidly removing the solvent after the upper layer coating.

  Moreover, in order to provide a new function, in some cases, the partial compatibility at the interface between the upper layer and the lower layer is positively performed within a range where the effects of the present invention are sufficiently exhibited. Such a method is carried out by adjusting the degree of any of the above methods using the difference in solvent solubility and the method of drying the solvent very quickly after the second layer is applied.

The concentration of the above components (total solid content including additives) in the lower layer / upper layer coating solution coated on the support is preferably 1% by mass to 50% by 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 when the upper layer is applied, the upper layer application method is preferably a non-contact type. Further, 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 desirable to perform coating by forward rotation in order to prevent damage to the lower layer.

Coating amount after the underlying drying applied on the support of the lithographic printing plate precursor of the present invention, the range from the viewpoint of printing durability and image reproducibility, of 0.5g ^/ m ² ~4.0g / m 2 preferably in the, still more preferably from ^{0.6g / m 2 ~2.5g / m 2} .
The coating amount after the upper layer of drying, sensitivity, development latitude, and from the viewpoint of scratch resistance ^is preferably in the range of ^{0.05g / m 2 ~1.5g / m 2} , more preferably 0.08g / M ^{2 to} 1.0 g / m ² .

The coating amount of the recording layer of the lower layer and the coating amount after drying of the combined upper or single layer, from the viewpoint of printing durability and image reproducibility, in the range of 0.6g ^/ m ² ~4.0g / m 2 preferably there, still more preferably from ^{0.7g / m 2 ~2.5g / m 2} .

(Aluminum support)
As an aluminum support for use in a lithographic printing plate precursor, a dimensionally stable plate is preferably used because it is relatively inexpensive. Suitable aluminum plates are a pure aluminum plate and an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. Even if the content of the different elements in the alloy is large, it is 10% by mass or less. The thickness of the aluminum plate is preferably about 0.1 mm to 0.6 mm, more preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

The aluminum plate is subjected to various surface treatments such as roughening and anodizing treatment.
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 roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization treatment to enhance the surface water retention and wear resistance as desired. 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, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

The conditions for the anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. In general, the concentration of the electrolyte is 1% by mass to 80% by mass, the liquid temperature is 5 to 70 ° C., and the current density. Is 5 A / dm ^{2 to} 60 A / dm ² , the voltage is 1 V to 100 V, and the electrolysis time is preferably 10 seconds to 5 minutes. The amount of the anodized film by the anodization is preferably 1.0 g / m ² or more. When the amount of the anodic oxide film is less than 1.0 g / m ² , the printing durability is insufficient, or when used as a lithographic printing plate, the non-image area may be easily damaged. As a result, a so-called “scratch stain” in which ink adheres to a scratched part during printing may be likely to occur.

  After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment as necessary. The hydrophilization treatment method is disclosed in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. The alkali metal silicate (for example, sodium silicate aqueous solution) method is mentioned. 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 And a method of treating with polyvinyl phosphonic acid as disclosed in the literature.

<Preparation method of lithographic printing plate>
An exposure step of exposing the positive photosensitive lithographic printing plate according to the present invention imagewise with an infrared laser, and the exposed lithographic printing plate precursor after contact with the treatment liquid composition of the present invention for recording A lithographic printing plate is produced by performing a development step of removing the exposed area of the layer and hydrophilizing the surface of the aluminum support exposed by removing the recording layer.

<Exposure process>
In the method for preparing a lithographic printing plate of the present invention, first, an exposure step of exposing the positive photosensitive lithographic printing plate imagewise is performed. The image-like exposure may be performed by laser exposure through a lith film (a transparent original image having a line image, a halftone dot image, etc.) formed in advance, or laser scanning exposure may be performed by digital data.
Since the lithographic printing plate precursor used in the method of the present invention has an infrared sensitive positive recording layer, the light source wavelength used in the exposure step is preferably in the range of 750 nm to 1400 nm. As the light source of 750 nm to 1400 nm, a solid-state laser and a semiconductor laser that emit infrared rays are suitable.
The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like.

<Development process>
The development step in the method for preparing a lithographic printing plate of the present invention comprises the treatment liquid composition of the present invention, that is, a pH of 5 to 10.7, a structural unit having a betaine structure in the side chain, and an aluminum support in the side chain. It is characterized by using an aqueous solution containing a water-soluble polymer compound containing a structural unit having a functional group that interacts with the body surface as a constituent component.
According to the method for producing a lithographic printing plate of the present invention, the positive recording layer in the unexposed area is removed by the development treatment, the recording layer is removed, and the exposed aluminum support surface is hydrophilized. . For this reason, the lithographic printing plate after the development treatment can be dried and then immediately set in a printing machine and printed without performing the water washing step and the gumming step which are usually performed after the development step.
In the conventional development process using an alkali developer, the lithographic printing plate after alkali development is washed with water to remove the alkali agent in a water washing step before being mounted on a printing machine, and the hydrophilic treatment of the non-image area with a gum solution is performed. It is necessary to dry in the drying process. On the other hand, in the preparation method of the present invention, since the specific water-soluble polymer compound is contained in the processing liquid composition, the development and gum solution processing steps can be performed simultaneously. Therefore, the post-water washing step is not particularly required, and after performing development and gum solution treatment with one solution, printing can be immediately performed through a drying step.
In addition, it is preferable to perform a drying process, after removing an excess process liquid composition using a squeeze roller after a development process.

  One of the features of the method for producing a lithographic printing plate according to the present invention is that no water washing step is required. Here, “not including a water washing step” includes all water washing steps from the image exposure step of the positive photosensitive lithographic printing plate to the preparation of the lithographic printing plate through the development processing step. Means no. That is, according to this aspect, a lithographic printing plate is produced without performing a water washing step not only between the image exposure step and the development processing step but also after the development processing step. The produced printing plate can be dried and used for printing as it is after removing moisture.

  The development step is a method in which the image-exposed lithographic printing plate precursor is immersed in the treatment liquid composition and rubbed with a brush in a temperature range of about 0 ° C. to 60 ° C., preferably about 15 ° C. to 40 ° C., according to a conventional method, The treatment liquid composition can be sprayed by spraying and rubbed with a brush.

The development processing in the present invention can be preferably carried out by an automatic development processor equipped with a processing solution composition supply means and a rubbing member. An automatic developing processor using a rotating brush roll as the rubbing member is particularly preferable.
Two or more rotating brush rolls are preferable. Furthermore, it is preferable that the automatic developing machine is provided with a means for removing excess processing liquid composition such as a squeeze roller and a drying means such as a hot air device after the development processing means.

  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.

  FIG. 1 schematically shows an example of the structure of an automatic developing processor suitably used in the method for preparing a lithographic printing plate according to the present invention. The automatic development processor shown in FIG. 1 basically comprises a developing unit 6 and a drying unit 10, and the lithographic printing plate precursor 4 is developed and gummed in the developing tank 20 and dried in the drying unit 10. Specifically, in FIG. 1, the lithographic printing plate precursor 4 inserted into the automatic developing device is conveyed to the developing unit 6 by a conveying roller (loading roller) 16. In the developing tank 20 of the developing unit 6, a conveyance roller 22, a brush roller 24, and a squeeze roller 26 are sequentially provided from the upstream side in the conveyance direction, and a backup roller 28 is provided at an appropriate position therebetween. The lithographic printing plate precursor 4 is immersed in a specific developer while being conveyed by the conveyance roller 22 and the brush roller 24 is rotated, whereby the development and gumming of the lithographic printing plate precursor 4 are performed. The developed lithographic printing plate precursor 4 is conveyed to the next drying unit 10 by a squeeze roller (carry-out roller) 26. The drying unit 10 is provided with two pairs of guide rollers 36 and two pairs of skewer rollers 38 in order from the upstream side in the transport direction. The drying unit 10 is provided with drying means such as hot air supply means and heat generation means (not shown), and the planographic printing plate precursor 4 conveyed to the drying unit 10 is dried by the drying means.

The lithographic printing plate obtained as described above can be subjected to a printing process. However, when it is desired to obtain a lithographic printing plate having a higher printing durability, a burning process is performed. In the case of burning a lithographic printing plate, before burning, an adjustment as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 is used. It is preferable to treat with a surface liquid. The lithographic printing plate coated with the surface-adjusting solution is dried if necessary, and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). Is done. The heating temperature and time in this case are preferably about 1 to 20 minutes at a temperature of 180 to 300 ° C., although it depends on the type of components forming the image. The heating conditions are appropriately selected depending on the type of the lithographic printing plate precursor to be used. In general, when the temperature is too low, when the heating time is insufficient, sufficient image strengthening action cannot be obtained, and the temperature is If it is too high or if the heating time is too long, problems such as deterioration of the support and thermal decomposition of the image area may occur.
The lithographic printing plate thus obtained is loaded on an offset printing machine and used for printing a large number of sheets.

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.
[Examples 1 to 12, Comparative Examples 1 to 4]
(Preparation of positive planographic printing plate precursor 1 used for evaluation)
<Synthesis of polyurethane resin: Synthesis example 1>
In a 500 ml three-necked flask, 125 g of 4,4′-diphenylmethane diisocyanate and 67 g of 2,2-bis (hydroxymethyl) propionic acid were dissolved in 290 ml of dioxane. After adding 1 g of N, N-diethylaniline, the mixture was stirred for 6 hours under reflux of dioxane. After the reaction, the polymer was precipitated little by little into a solution of 4 L of water and 40 cc of acetic acid. This solid was vacuum-dried to obtain 185 g of polyurethane resin (1). The acid content was 2.47 meq / g. When the molecular weight was measured by GPC, the weight average (polystyrene standard) was 28,000.

<Production of support>
0.24 mm thick aluminum plate (Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.014 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn : 0.001% by mass, Ti: 0.03% by mass, the balance being Al and an inevitable impurity aluminum alloy) was subjected to the following surface treatment continuously.

  An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a nitric acid 10 g / liter aqueous solution (containing 5 g / liter of aluminum ions and 0.007 mass% of ammonium ions) at a temperature of 80 ° C. After washing with water, the aluminum plate was etched by spraying at 32 ° C. with a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass%, the aluminum plate was dissolved at 0.20 g / m 2, and washed with water. Thereafter, a desmut treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid having a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), and washing with water by spraying was performed.

Anodization was performed using an anodizing apparatus of a two-stage power supply electrolytic treatment method. Sulfuric acid was used as the electrolytic solution supplied to the electrolysis unit. Then, water washing by spraying was performed. The final oxide film amount was 2.7 g / m ² .
The aluminum support obtained by the anodizing treatment is immersed in a treatment tank of 1 mass% aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C. for 10 seconds for alkali metal silicate treatment (silicate treatment). It was. Then, water washing by spraying was performed.
On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds to form a coating film. The coating amount of the coating film after drying was 15 mg / m ² .

-Undercoat liquid-
・ Β-Alanine 0.5g
・ Methanol 95g
・ Water 5g

<Formation of positive recording layer>
After applying the lower layer coating solution 1 having the following composition to the support obtained as described above with a bar coater so that the coating amount becomes 1.5 g / m ² , it is dried at 160 ° C. for 44 seconds and immediately 17 to 20 ° C. The support was cooled to 35 ° C. with cold air.

-Lower layer coating solution 1-
N-phenylmaleimide / methacrylic acid / methacrylamide copolymer (composition ratio: 59 mol% / 15 mol% / 26 mol%, weight average molecular weight 45,000) 3.33 g
M, p-cresol novolak resin (m / p ratio = 6/4, weight average molecular weight 4500, containing 0.8% by mass of unreacted cresol) 1.88 g
-0.94 g of cyanine dye A represented by the following structural formula
・ Crystal Violet (Hodogaya Chemical Co., Ltd.) 0.08g
・ Megafac F-177 (manufactured by DIC Corporation, fluorosurfactant) 0.05 g
・ Γ-Butyllactone 10g
・ Methyl ethyl ketone 61g
・ 14g of 1-methoxy-2-propanol
・ Water 9.34g

Thereafter, the upper layer coating solution 1 having the following composition was applied to the surface of the formed lower layer by a bar coater so that the coating amount was 0.5 g / m ² , and then dried at 130 ° C. for 40 seconds, and further 20 to 26 The lithographic printing plate precursor 1 used in Example 1 was prepared by gradually cooling with a wind of ° C.

-Coating liquid for upper layer 1-
-30.0 g of polyurethane resin (1) obtained in Synthesis Example 1
・ Ethyl violet 0.03g
・ Megafac F-177 (manufactured by DIC Corporation, fluorosurfactant) 0.05 g
・ 3-Pentanone 60g
・ Propylene glycol monomethyl ether-2-acetate 8g

<Preparation of treatment liquid composition>
In the basic formulation shown in Table 1 below, the specific water-soluble polymer compound or the comparative water-soluble polymer compound shown in Table 2 (in Table 1 and Table 2, the specific water-soluble polymer and the comparative water-soluble polymer are described respectively. ) And the components were stirred well to dissolve the water-soluble polymer compound, thereby preparing a processing solution composition for use in the development process. In addition, the unit of the numerical value which shows content in Table 1 is g, and "-" shows that the compound is not contained.

  The structures of the specific water-soluble polymer compounds shown in Table 1 and the comparative water-soluble polymer compounds used for the preparation of the treatment liquid compositions of Comparative Examples are shown below.

<Preparation and evaluation of planographic printing plates>
The obtained lithographic printing plate precursor was subjected to plate making treatment by an exposure step and a development step according to the production method of the present invention, and each evaluation shown below was performed.
The obtained lithographic printing plate precursor was cut into a size of 1030 mm × 800 mm, and a test pattern was drawn in an image with an exposure energy of 150 mJ / cm ^{2 using a} Trend setter manufactured by Creo.
(Development process)
Thereafter, using each processing solution composition having the above composition, an automatic developing processor shown in FIG. 1 [developing tank 25L, plate conveyance speed 100 cm / min, polybutylene terephthalate fiber (hair diameter 200 μm, hair length 17 mm) was implanted. One brush roll having a diameter of 50 mm is developed at 200 revolutions per minute in the same direction as the conveying direction (peripheral speed of brush tip 0.52 m / sec), drying temperature 80 ° C.] to obtain a lithographic printing plate It was. The processing solution composition temperature in the developing bath was 30 ° C.

About the preparation methods using each processing liquid, the developability, initial printing stain resistance, stain resistance after printing interruption and printing durability of the planographic printing plate precursor were evaluated as follows. The results are shown in Table 2 above.
<Developability>
The lithographic printing plate precursor was exposed and developed as described above. The non-image area of the obtained lithographic printing plate was visually confirmed, and the remaining recording layer was evaluated. Evaluation was carried out according to the following criteria.
◯: Good developability without remaining recording layer Δ: Slight recording layer remaining but no problem in developability ×: Recording layer remained, poor developability <initial printing stain>
The planographic printing plate was printed as described above, and the smudge of the non-image area was evaluated on the 1000th printed material. Evaluation was carried out according to the following criteria.
○: There is no ink smudge in the non-image area. Δ: Slight ink smudge is present in the non-image area. ×: Ink smudge is present in the non-image area.
The lithographic printing plate was printed as described above, and when 50,000 sheets were printed, the printing machine was temporarily stopped and left for 3 hours. Thereafter, printing was resumed, 200 sheets were further printed, and the number of sheets until the ink completely disappeared from the non-image area was evaluated.
It can be said that the smaller the number of sheets, the smaller the amount of lost paper from the re-start of printing, and the better the stainability after printing is interrupted.
<Print durability>
As the number of printed sheets is increased, the image on the recording layer formed on the planographic printing plate is gradually worn out and the ink receptivity is lowered. Accordingly, the ink density of the image on the printing paper is lowered. Printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing. The larger the value, the better the printing durability.

  From the results shown in Table 2, the method for preparing a lithographic printing plate using the treatment liquid composition containing the specific water-soluble polymer compound according to the present invention is a simple process of one liquid and one process that does not require a water washing process. The non-image area was free from contamination due to the remaining recording layer, exhibited good developability, and had good printing durability. In addition, the results of the evaluation of stain resistance after interruption of printing confirmed that the non-image area is excellent in stain resistance, that is, surface hydrophilicity, even after printing a large number of sheets. It can be seen that a printed version is provided.

4 Planographic printing plate precursor 6 Developing unit 10 Drying unit 16 Transport roller 20 Developing tank 22 Transport roller 24 Brush roller 26 Squeeze roller 28 Backup roller 36 Guide roller 38 Skewer roller

Claims (8)

An exposure step of imagewise exposing a positive photosensitive lithographic printing plate having an infrared sensitive positive recording layer on an aluminum support with an infrared laser;
The lithographic printing plate precursor after exposure, pH is from 5 to 10.7, a structural unit having a betaine structure in a side chain, a functional group capable of interacting with the aluminum support surface in a side chain, phosphorus An exposed portion region of the recording layer by contacting with an aqueous solution containing a water-soluble polymer compound comprising , as a constituent , a structural unit having one or more functional groups selected from an oxygen acid group and an onium group and removal of, a developing step of performing the hydrophilic treatment of the recording layer is exposed by removing the aluminum support surface, a method of preparing a lithographic printing plate having in this order. The method for producing a lithographic printing plate according to claim 1 , wherein the oxygen acid group of phosphorus is a phosphate ester group or a phosphonic acid group. Wherein the aqueous solution further method of preparing a lithographic printing plate according to claim 1 or claim 2 containing carbonate ion and a hydrogen carbonate ion. The method for producing a lithographic printing plate according to any one of claims 1 to 3 , wherein the aqueous solution further contains 0.01% by mass to 20% by mass of a surfactant. The method for preparing a lithographic printing plate according to any one of claims 1 to 4 , wherein a washing step is not provided after the developing step. The method for producing a lithographic printing plate according to any one of claims 1 to 5 , wherein the recording layer comprises (A) an infrared absorber and (B) a water-insoluble and alkali-soluble resin. The recording layer is a recording layer having a multilayer structure comprising (C) a lower layer containing an alkali-soluble resin and (B) an upper layer containing a water-insoluble and alkali-soluble resin, and at least one of the upper layer and the lower layer The method for producing a lithographic printing plate according to any one of claims 1 to 6 , wherein the layer contains (A) an infrared absorber. A structural unit having a betaine structure in the side chain, and a functional group that interacts with the surface of the aluminum support on the side chain, the structure having at least one functional group selected from an oxygen acid group of phosphorus and an onium group A positive photosensitive lithographic printing comprising a water-soluble polymer compound containing a unit as a constituent component and water, having a pH of 5 to 10.7 and having an infrared-sensitive positive recording layer on an aluminum support A treatment liquid composition used for plate making of a plate precursor.