JP2013218315A - Original plate for lithographic printing plate and lithographic printing plate production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original plate for a lithographic printing plate which has a large difference between solubility resistance to a developing solution for image portions and solubility for non-image portions, and exhibits a high printing durability and good chemical resistance for image portions and good solubility for non-image portions.SOLUTION: The original plate for a lithographic printing plate has at least two recording layers including an alkali-soluble resin, upon a surface hydrophilic support body. At least one layer is a positive recording layer containing an infrared absorbent. The recording layer closest to the support body, among the at least two recording layers, contains: (A) an alkali-soluble polyurethane having an acid group; and (B) a (meth)acrylic resin having a repeating unit selected from structural units represented by general formulas (I) and (II). In the general formulas (I) and (II): Arand Areach represent an aromatic group, and at least one of them is a heteroaromatic group; and a and b each represent 0 or 1.

Description

  The present invention relates to a lithographic printing plate precursor and a method for producing a lithographic printing plate using the lithographic printing plate precursor, and in particular, positive lithographic printing for infrared laser for so-called direct plate making, which can be directly made from a digital signal of a computer or the like. The present invention relates to a plate precursor and a method for producing a lithographic printing plate using the same.

  In recent years, the development of lasers has been remarkable, and in particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can easily obtain high-power and small-sized ones. At present, various photosensitive compositions are used as a recording layer material for visible image forming materials and planographic printing plate precursors, and when such photosensitive compositions are directly imaged from digital data such as computers. These lasers are very useful as exposure light sources.

  The positive type lithographic printing plate precursor for infrared laser has an alkaline aqueous solution-soluble binder resin and an infrared absorbing dye (IR dye) that absorbs light and generates heat as essential components. In the image area), it acts as a dissolution inhibitor that substantially lowers the solubility of the binder resin by interaction with the binder resin. In the exposed area (non-image area), the generated heat causes the IR dye and the binder resin to react with each other. The interaction weakens and dissolves in an alkaline developer to form a lithographic printing plate.

  However, in such a positive lithographic printing plate precursor for infrared laser, there is a difference between the solubility of the non-exposed portion (image portion) in the developing solution and the solubility of the exposed portion (non-image portion) under various usage conditions. However, there is a problem that over-development and poor development are likely to occur due to fluctuations in use conditions. In addition, even when the surface condition slightly changes due to touching the surface during handling, the unexposed area (image area) dissolves and becomes scratched during development, causing deterioration in printing durability and poor inking properties. There was a problem.

  Such a problem is derived from the essential difference in the plate making mechanism between the positive lithographic printing plate precursor for infrared laser and the positive lithographic printing plate material made by UV exposure. That is, in a positive planographic printing plate precursor made by UV exposure, an alkaline aqueous solution-soluble binder resin and an onium salt or a quinonediazide compound are essential components. The onium salt or the quinonediazide compound is an unexposed portion ( In addition to acting as a dissolution inhibitor by interacting with the binder resin in the image area), the exposed area (non-image area) plays two roles: it decomposes by light to generate acid and acts as a dissolution accelerator. Is.

  On the other hand, the IR dye or the like in the positive lithographic printing plate precursor for infrared laser only serves as a dissolution inhibitor for the non-exposed portion (image portion), and does not promote dissolution of the exposed portion (non-image portion). . Therefore, in the positive type lithographic printing plate precursor for infrared laser, in order to obtain a difference in solubility between the non-exposed portion and the exposed portion, a binder resin having high solubility in an alkali developer must be used in advance. The state before development becomes unstable. Further, in such a lithographic printing plate precursor, an ink-receptive recording layer is formed on a hydrophilic support, so that the adhesion of the recording layer at the support interface becomes unstable, and the unexposed area (image area) There is a problem in that it also affects printing durability, and this problem is particularly remarkable in the reproducibility of small area images such as fine lines and halftone dots. In particular, in recent years, it has been desired to increase the resolution of images, and to improve image reproducibility by high-resolution exposure in order to meet the demand.

  In order to solve the above problems, various proposals have been made. For example, in order to improve image discrimination, a method of unevenly distributing an infrared absorber in a film has been proposed (see, for example, Patent Document 1). As a result, although the improvement of the disc million is seen, there is still room for improvement from the viewpoint of fine line reproducibility.

For the purpose of improving the removability of the exposed part, a lower layer containing a polymer containing a structural unit containing —NH— and —SO ₂ — structures in the side chain, and an upper thermosensitive layer containing a phenolic resin and an infrared absorber There has been proposed a lithographic printing plate precursor having a recording layer having a multi-layered structure in which a slab is sequentially provided on a hydrophilic substrate (see, for example, Patent Document 2).
In addition, from the viewpoint of improving printing durability and solvent resistance in the image area, a method of blending a polymer in the lower layer of the multilayer recording layer (see, for example, Patent Document 3), and a urethane resin in the lower layer of the multilayer recording layer A method to be used (for example, see Patent Document 4) has been proposed.
Such an image recording layer having a multi-layer structure is a problem of a positive image forming layer for infrared laser by using a resin excellent in alkali solubility in the lower layer, and an effect that an undesired residual film is quickly removed. In addition, the lower layer functions as a heat insulating layer, which effectively suppresses thermal diffusion to the support and improves image formation.

JP 2001-281856 A European Patent Publication No. 1826001A1 JP-A-2005-242241 US Patent Publication 2012 / 0052445A Specification

However, in order to form a recording layer having the multi-layer structure as described above, it is necessary to select resins having different characteristics as the resins used for each layer constituting the recording layer, and their interactivity is reduced. Inferior in chemical resistance, such as being susceptible to damage by the developer, ink cleaning solvent used during printing, plate cleaner, etc. In particular, when ultraviolet curable so-called UV ink is used as the printing ink, there is a problem that the printing durability of the image portion becomes insufficient, and improvement is desired at present.
The first object of the present invention, which has been made in consideration of the above-mentioned problems of the prior art, is the difference between the dissolution resistance of the non-exposed portion (image portion) to the developer and the solubility of the exposed portion (non-image portion). Is to provide a lithographic printing plate precursor that has a sufficient difference (also called development discretion) and is excellent in both high printing durability and chemical resistance in the image area and solubility in the non-image area. .
The second object of the present invention is to provide a method for producing a lithographic printing plate in which the generation of development residue due to the precipitation of the recording layer component in the developer used during plate making of the lithographic printing plate precursor is suppressed. is there.

As a result of intensive studies, the present inventors have found that the above problem can be solved by using a specific two kinds of resins in the recording layer existing in the vicinity of the support in the positive recording layer having a multilayer structure, The present invention has been completed.
That is, the lithographic printing plate precursor according to the first embodiment of the present invention has two or more recording layers containing an alkali-soluble resin on a surface hydrophilic support, and at least of the two or more recording layers. One layer contains an infrared absorber, and is a positive recording layer whose solubility in an alkaline aqueous solution is increased by infrared laser exposure, and of the two or more recording layers, the recording layer closest to the support Is (A) an alkali-soluble polyurethane having an acid group, and (B) one or more selected from a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II) (Meth) acrylic resin having a repeating unit.

In the general formula (I) and general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —N (R ² ) —, wherein R ² represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Ar ¹ and Ar ² each independently represent an aromatic group, and at least one of them is a heteroaromatic group. a and b each independently represents 0 or 1;
In the second embodiment of the present invention, the (A) alkali-soluble polyurethane having an acid group is preferably neutralized with a monovalent basic compound.
In the third embodiment of the present invention, the positive recording layer closest to the support comprises (A) the alkali-soluble polyurethane having an acid group and (B) the structure represented by the general formula (I). The content ratio of the unit and the (meth) acrylic resin having one or more repeating units selected from the structural unit represented by the general formula (II) (that is, (A) specific alkali-soluble polyurethane: (B) The specific (meth) acrylic resin) preferably contains a resin having a mass ratio of 95: 5 to 30:70.

Moreover, the method for producing a lithographic printing plate according to the fourth embodiment of the present invention includes an exposure process for image exposure of the lithographic printing plate precursor according to the first to third embodiments of the present invention, and a post-exposure process. A method for producing a lithographic printing plate comprising, in this order, a development step of developing the lithographic printing plate precursor using an aqueous alkali solution containing a surfactant of 0.5 mass% to 5.0 mass%.
The surfactant contained in the developer is preferably at least one selected from an anionic surfactant having a sulfonate and an anionic surfactant having a carboxylate.
Moreover, it is preferable that the said image development process is implemented on the conditions that the liquid temperature of a developing solution is 20 degreeC or more and 25 degrees C or less, and development time is 5 seconds or more and 20 seconds or less.

  Hereinafter, in this specification, the “positive recording layer closest to the support” is appropriately referred to as “lower layer” or “lower recording layer”.

  The lithographic printing plate precursor according to the present invention has, on the hydrophilic surface of a support having a hydrophilic surface, in addition to the plurality of positive recording layers, if desired, other layers such as a surface protective layer and an undercoat layer. May be provided as long as the effects of the present invention are not impaired, and a backcoat layer or the like may be provided on the surface of the support that does not have a positive recording layer, if desired.

Although the details of the mechanism of action of the present invention are unknown, it is considered as follows.
In the lower recording layer of the lithographic printing plate precursor according to the invention, (A) an alkali-soluble polyurethane having an acid group (hereinafter appropriately referred to as a specific polyurethane) and (B) a structural unit represented by the following general formula (I) And a (meth) acrylic resin (hereinafter appropriately referred to as a specific acrylic resin) having one or more types of repeating units selected from structural units represented by the following general formula (II). It is estimated that polyurethane and (B) specific acrylic resin are excellent in compatibility, and a uniform resin layer is formed by containing two kinds of resins. (B) The specific acrylic resin has a side chain structure represented by the general formula (I) or the general formula (II), that is, a bulky aromatic group on both sides of the sulfonamide linking group, and at least one of them By including the structure that the aromatic group is a heteroaromatic group, it is considered that both the burning printing durability and the chemical resistance are excellent. (B) In addition to improving the burning printing durability and chemical resistance due to the side chain structure of the specific acrylic resin, (A) Only the improvement in the flexibility and chemical resistance of the recording layer due to the urethane bond contained in the specific polyurethane Rather, when both are uniformly mixed, the partial structures in both resins, in particular, (B) the heteroaromatic group of the specific acrylic resin and (B) the urethane bond in the specific polyurethane form an interaction. . For this reason, it is considered that high polarity is achieved in the lower recording layer, and the printing durability when UV ink is used is further improved.
Furthermore, when the recording layer contains an infrared absorber, each of them forms an interaction with the infrared absorber, so that in the unexposed area, the film strength and chemical resistance of the recording layer are further improved. On the other hand, in the exposure area, both the interaction between the resins and the interaction between the infrared absorber and the resin that are optionally contained are quickly released, and (B) the sulfonamide structure of the specific acrylic resin, (A) Since the solubility with respect to the aqueous alkali solution resulting from the acid group which a specific polyurethane has is expressed, it is thought that it is excellent in the dissolution discrepancy at the time of recording.

According to the present invention, a sufficient difference between the dissolution resistance of the non-exposed portion with respect to the developer and the solubility of the exposed portion can be obtained, and the high printing durability and chemical resistance in the image portion can be obtained. Therefore, it is possible to provide a lithographic printing plate precursor having good solubility.
Further, according to the present invention, it is possible to provide a method for producing a lithographic printing plate in which the generation of development residue due to the precipitation of the recording layer component in the developer used at the time of making the lithographic printing plate precursor is suppressed. .
Furthermore, as an unexpected effect, the use of the lithographic printing plate precursor according to the present invention provides a method for preparing a lithographic printing plate with improved printing durability when UV ink is used.

It is a graph which shows an example of the alternating waveform current waveform figure used for the electrochemical roughening process in preparation of the support body using the lithographic printing plate precursor of an Example. It is a side view which shows an example of the radial type cell in the electrochemical roughening process using alternating current in preparation of the support body using the lithographic printing plate precursor of an Example.

Hereinafter, the lithographic printing plate precursor according to the invention and the method for producing a lithographic printing plate using the same will be described in detail.
In addition, although described in this specification based on the typical embodiment of this invention, unless the main point of this invention is exceeded, this invention is not limited to described embodiment.
In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, in the present specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. means.
In the notation of groups (atomic groups) in this specification, the notation that does not indicate substitution and non-substitution includes not only those having no substituent but also those having a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended action of the process is achieved even when it cannot be clearly distinguished from other processes. .

In this specification, “(meth) acrylic resin” for indicating either or both of acrylic resin and methacrylic resin, “(meth) acrylic acid” for indicating either or both of acrylic acid and methacrylic acid, and acrylate In order to indicate either or both of methacrylate, “(meth) acrylate” may be indicated.
In addition, unless otherwise specified, the content is expressed in terms of mass, and unless otherwise specified, mass% represents a ratio to the total amount of the composition, and “solid content” refers to a component excluding the solvent in the composition. Represent.

<Lithographic printing plate precursor>
The lithographic printing plate precursor according to the invention has two or more recording layers containing an alkali-soluble resin on a surface hydrophilic support, and at least one of the two or more recording layers contains an infrared absorber. A positive recording layer whose solubility in an aqueous alkali solution is increased by infrared laser exposure, and of the two or more recording layers, the recording layer closest to the support is (A) an alkali having an acid group. Soluble polyurethane (hereinafter referred to as specific polyurethane as appropriate) and (B) one or more repeating units selected from the structural unit represented by the following general formula (I) and the structural unit represented by the following general formula (II) A (meth) acrylic resin having a unit (hereinafter, appropriately referred to as a specific acrylic resin) is contained.

In the general formula (I) and general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —N (R ² ) —, wherein R ² represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Ar ¹ and Ar ² each independently represent an aromatic group, and at least one of them is a heteroaromatic group. a and b each independently represents 0 or 1;
In the above formula, R ¹ , R ² , Ar ¹ and Ar ² may each independently further have a substituent.

[(A) Alkali-soluble polyurethane having an acid group (specific polyurethane)]
The specific polyurethane that can be used in the present invention is a polymer produced by an addition reaction of a compound having two or more isocyanate groups and a compound having two or more hydroxyl groups, and includes a carboxylic acid group, a sulfonic acid group, There is no particular limitation as long as the polyurethane has an acidic group selected from a phosphoric acid group, a phosphonic acid group, an aromatic hydroxyl group, and an acidic amide or imide group. Particularly preferred is a polyurethane having a carboxylic acid group.
Here, “alkali-soluble” means that the specific polyurethane is dissolved in an alkaline aqueous solution (pH: 10) at 25 ° C. in an amount of 0.1% by mass or more.

Examples of the polyurethane used in the present invention include, for example, JP-A-63-124047, JP-A-63-287946, JP-A-2-866, JP-A-2-156241, and JP-A-2003-177533. Polyurethanes having the structures described in JP-A No. 2004-170525, JP-A No. 2004-239951, JP-A No. 2004-157459, and JP-A No. 2005-250158 are preferably used.
As a preferred specific example of the polyurethane that can be used in the present invention, PU-1 to PU-18 are represented by the molar ratio of the raw material monomer and the used polyurethane and the weight average molecular weight (Mw) of the obtained specific polyurethane. Needless to say, the resin is not limited thereto.
In addition, the number described under each monomer name below represents the molar ratio of each monomer used, and PU-1 to PU-18 represent a specific polyurethane as a reaction product of each monomer described in Table 1. means.
Moreover, the weight average molecular weight of a polymer is the value measured by the gel permeation chromatography (GPC) method.

  Moreover, the structure of each compound shown by the symbol in Table 1 is as shown below.

Among them, preferable specific polyurethanes include “PU-1”, “PU-3”, “PU-11”, “PU-15”, “PU-18” and the like in Table 1.
As the specific polyurethane used in the present invention, the molecular weight (weight average molecular weight) is preferably from 5,000 to 500,000, preferably from 10,000 to 200,000, from the viewpoints of developability and printing durability. More preferred is 20,000 to 100,000.
The content of the acid group in the alkali-soluble polyurethane having an acid group is included in a range where the acid value of the specific polyurethane is 0.01 mmol / g to 3.50 mmol / g from the viewpoint of the balance between developability and printing durability. It is more preferable. More preferably, it is 0.50 mmol / g-3.00 mmol / g, More preferably, it is 1.00 mmol / g-2.60 mmol / g.
In the present invention, the content of the alkali-soluble polyurethane having an acid group is preferably in the range of 1% by mass to 99% by mass with respect to the total solid content in the positive recording layer closest to the support. More preferably, it is in the range of mass% to 95 mass%, and most preferably in the range of 50 mass% to 90 mass%. When the amount of the specific polyurethane added is 50% by mass or more, the formed positive-type recording layer has excellent durability, and when the content is 90% by mass or less, the recording layer has a sensitivity. In addition, the chemical resistance is excellent, the dispersibility of the residue in the developer is improved, and the generation of residue due to the aggregation of precipitates in the developer bath is suppressed.

In the specific polyurethane (A) used in the present invention, at least a part of the acid groups of the specific polyurethane may be neutralized with a monovalent basic compound. The monovalent basic compound used for neutralizing the acid group will be described.
(Monovalent basic compound)
The monovalent basic compound used for neutralization of the specific polyurethane used in the lower layer in the present invention is a monovalent basic compound capable of forming a salt structure with the acid group in the polyurethane having the acid group described above. Meaning and preferred examples include alkali metal hydroxides or oxides, bicarbonates, alkoxides (ROM), phenoxides (ArONa), ammonia (gas or aqueous solution), diarylamines and triarylamines. Examples include amines, heterocyclic bases such as pyridine, quinoline, and piperidine, hydrazine derivatives, amidine derivatives, onium hydroxides, and the like. Here, diarylamine and triarylamine are almost neutral, and are not preferable as the monovalent basic compound in the present invention because of insufficient salt formation with an acid group.
The monovalent basic compound used for neutralization of the acid group preferably has a pKa of the conjugate acid of 8 to 20, more preferably 10 to 18, and most preferably 11 to 17. . When the pKa of the conjugate acid is 8 or more, the dissolution discrepancy of the recording layer formed including the specific polyurethane is improved, and when the pKa is 20 or less, there is an adverse effect on the stability and manufacturability of the compound. This is because it is suppressed, and stability and production suitability are maintained well. In the present specification, pKa refers to a value measured at 25 ° C. unless otherwise specified. In addition, all the exemplary compounds described below belong to the range of pKa of 8-20.
Among the monovalent basic compounds that can be used in the present invention, alkali metal hydroxides or oxides, bicarbonates, alkoxides (ROM), phenoxides (ArONa), ammonia (gas or aqueous solution). And nitrogen-containing compounds are preferable, and nitrogen-containing basic compounds shown below, that is, nitrogen-containing basic compounds having partial structures represented by the following formulas (A) to (E) are preferable.

In the formula (A), R ²⁵⁰ , R ²⁵¹ and R ²⁵² each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and R ²⁵¹ and R ²⁵² May combine with each other to form a ring. The alkyl group and aryl group may further have one or more substituents selected from a hydroxy group, an amide group, an ester group, and the like.

In formula (E), R ²⁵³ , R ²⁵⁴ , R ²⁵⁵ and R ²⁵⁶ each independently represents an alkyl group having 1 to 20 carbon atoms.
Specific examples of the monovalent basic compounds that can be used in the present invention having preferred partial structures represented by these formulas (A) to (E) [Exemplary compounds (B-1) to (B-44)] Although listed below, the present invention is not limited to these.

  More preferable nitrogen-containing basic compounds include compounds having a nitrogen-containing ring in the molecule and nitrogen-containing basic compounds having two or more nitrogen atoms having different chemical environments in one molecule. The nitrogen-containing ring in the compound having a nitrogen-containing ring in the molecule is more preferably a polycyclic structure. Preferable examples of the compound having a nitrogen-containing ring in the molecule include compounds represented by the following formula (F).

In formula (F), Y and Z each independently represent a linear, branched or cyclic alkylene group which may contain a hetero atom. Here, examples of the hetero atom include a nitrogen atom, a sulfur atom, and an oxygen atom. As an alkylene group, a C2-C10 alkylene group is preferable, More preferably, it is a 2-5 thing.
The alkylene group may further have a substituent, and examples of the substituent that can be introduced include an alkyl group having 1 to 6 carbon atoms, an aryl group, an alkenyl group, a halogen atom, and a halogen-substituted alkyl group.
Specific examples of the basic compound having a nitrogen-containing ring in the molecule represented by the formula (F) include the following compounds [Exemplary compounds (B-45) to (B-52)].

Among the monovalent basic compounds, 1,8-diazabicyclo [5.4.0] undec-7-ene and 1,5-diazabicyclo [4.3.0] non-5-ene are particularly preferable.
The nitrogen-containing basic compound having two or more nitrogen atoms of different chemical environments in one molecule is particularly preferably a compound containing both a substituted or unsubstituted amino group and a ring structure containing a nitrogen atom, or alkyl The compound which has an amino group is mentioned. Specific examples of particularly preferred compounds include guanidine, 1,1-dimethylguanidine, 1,1,3,3-tetramethylguanidine, pyrazole, pyrazine, pyrimidine, 6-dihydroxypyrimidine, 2-pyrazoline, 3- Examples include pyrazoline, trimethylimidazole, triphenylimidazole, methyldiphenylimidazole, but are not limited thereto.

Onium hydroxide is also mentioned as a preferred embodiment of the monovalent basic compound. Specific examples of onium salts that can constitute onium hydroxide include ammonium salts, sulfonium salts, phosphonium salts, pyridinium salts, and the like, and these onium salts may further have a substituent.
As a more preferred embodiment of the onium hydroxide, structures represented by the general formula (1) to the general formula (4) are exemplified.

In general formula (1) to general formula (4), R ^{1 to} R ¹⁷ are each independently a monovalent substituent, a combination of R ^{1 to} R ^4, a combination of R ^{5 to} R ⁷ , and R ^{8 to} R. ^{Of the 11} combinations and the combinations of R ^{12 to} R ¹⁷ , at least two may be linked to each other to form a cyclic structure.
Examples of the monovalent substituent represented by R ^{1 to} R ¹⁷ include linear or branched alkyl groups, alicyclic groups (including cyclic alkyl groups), and heterocyclic groups (heteroaryl groups and heteroalicyclic rings). A monovalent substituent selected from an aryl group and an aralkyl group. These monovalent substituents may further have a substituent. Examples of the substituents that can be introduced include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups, aralkyl groups, halogen atoms, hydroxyl groups. Group, cyano group, amino group, amide group and the like.
Among these, R ^{1 to} R ¹⁷ are more preferably each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 6 to 20 carbon atoms.
Moreover, the compound which has a structure represented by General formula (5) or General formula (6) as a particularly preferable aspect of onium hydroxide is mentioned.

^R 1, ^{R 2} and ^{R 5} in the general formula (5) and general formula (6) has the general formula (1) and are respectively the same meanings as ^R 1, ^{R 2} and ^{R 5} in the general formula (2), preferably The range is the same. L and L ′ represent an atomic group necessary for forming a heterocycle represented by a nitrogen-containing heterocycle.
In the general formula (5) or the general formula (6), the heterocycle including N ⁺ is preferably a 5-membered ring or a 6-membered ring.

  Specific examples of preferred onium hydroxides [Exemplary compounds (O-1) to (O-20)] are shown below, but the present invention is not limited thereto.

These monovalent basic compounds are appropriately selected in relation to the acid group of the specific polyurethane to be neutralized, but from the viewpoint of development discretion, exemplary compounds (B-46, B-51, B -52, O-2, O-3, O-7, O-10, O-14) and the like are preferable.
These monovalent basic compounds may be used alone or in combination of two or more.
The amount of the basic compound added to the lower layer forming coating solution composition is usually 0.01% by mass to 30% by mass, preferably 0.5% by mass to 20% by mass, based on the total solid content of the lower layer.

In the lower layer in the present invention, the (A) polyurethane having an acid group and a monovalent basic compound are added to the coating liquid composition for forming the lower layer together with the (A) specific acrylic resin, which will be described later. (A) At least a part of the acid groups of the specific polyurethane forms a salt structure with the monovalent basic compound. The effect of the present invention can be expressed well even when part of the acid groups contained in the specific polyurethane (A) is neutralized, but the polarity of the lower recording layer itself is improved by neutralizing part of the acid groups. Therefore, the effect is considered to be further improved.
From such a viewpoint, the addition amount (neutralization amount) of the monovalent basic compound used for forming the salt structure with respect to the specific polyurethane (A) is from the viewpoint of interlayer mixing suppression, developability, and printing durability. It is preferably 10 mol% to 100 mol%, more preferably 15 mol% to 80 mol%, and most preferably 20 mol% to 60 mol% with respect to 100 mol% of the acid groups.
It can be confirmed that the carboxylic acid group in the formed lower layer forms a salt structure with a monovalent basic compound by measuring the acid value by a neutralization titration method.
Here, the carboxylic acid value of the polymer after forming the salt is preferably 0.001 mmol / g to 2.00 mmol / g, and more preferably 0.10 mmol / g to 1.80 mmol / g. 0.50 mmol / g to 1.60 mmol / g is most preferable.
Specific examples of the binder polymer suitable for the present invention having a salt structure formed by an alkali-soluble polyurethane having an acid group and a monovalent basic compound in the molecule are shown in the above (A) Although it shows by specifying clearly the kind and addition amount of a monovalent | monohydric basic compound used for neutralization of a polyurethane and this specific polyurethane, this invention is not limited to this.

Among them, preferable neutralized specific polyurethanes include “PN-13, PN-18, PN-24, PN-25, PN-27” and the like in Table 2.
As for the specific polyurethane used in the present invention, the molecular weight (weight average molecular weight) of the neutralized polyurethane is 5,000 to 500,500 from the viewpoint of developability and printing durability, as in the case of the unneutralized polyurethane. 000 is preferable, 10,000 to 200,000 is more preferable, and 20,000 to 100,000 is most preferable.
In the alkali-soluble polyurethane having acid groups, the preferred acid group content of the partially neutralized specific polyurethane is as described, but when the neutralized specific polyurethane and the non-neutralized specific polyurethane are used in combination The acid value of the mixture is preferably adjusted to be in the range of 0.50 mmol / g to 1.60 mmol / g.
The content of the alkali-soluble polyurethane having an acid group in the present invention is the total amount of neutralized and non-neutralized ones, and is 1 for the total solid content contained in the lower layer for the purpose of achieving the described effect. The range is preferably from mass% to 99 mass%, more preferably from 20 mass% to 95 mass%, and most preferably from 50 mass% to 90 mass%.

[(B) (Meth) acrylic resin (specific acrylic resin) having one or more repeating units selected from the structural unit represented by general formula (I) and the structural unit represented by general formula (II)]
Hereinafter, the specific acrylic resin will be described in detail.
The specific acrylic resin in the present invention is a polymer having at least one of a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II).

In the general formula (I) and general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —N (R ² ) —, wherein R ² represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Ar ¹ and Ar ² each independently represent an aromatic group, and at least one of Ar ¹ and Ar ² is a heteroaromatic group. a and b each independently represents 0 or 1;

In general formula (I), R ¹ represents a hydrogen atom or an alkyl group. When R ¹ represents an alkyl group, the alkyl group is a substituted or unsubstituted alkyl group, and preferably has no substituent. . Examples of the alkyl group represented by R ¹ include lower alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group. R ¹ is preferably a hydrogen atom or a methyl group.

Z represents —O— or —N (R ² ) —, and preferably represents —N (R ² ) —. Here, R ² represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group, preferably a hydrogen atom or an unsubstituted alkyl group, and more preferably a hydrogen atom.

In general formula (I) and general formula (II), a and b each independently represent 0 or 1, and a preferred embodiment is when a is 0 and b is 1, and when a and b are both 0 Or a and b are both 1, and most preferably a and b are both 1.
More specifically, in the structural unit, when a is 0 and b is 1, Z is preferably O. When both a and b are 1, Z is preferably —N (R ² ) —, where R ² is preferably a hydrogen atom.

Ar ¹ and Ar ² each independently represent an aromatic group, and at least one of them is a heteroaromatic group. Ar ¹ is a divalent aromatic group, and Ar ² is a monovalent aromatic group. These aromatic groups are substituents formed by replacing one or two hydrogen atoms constituting an aromatic ring with a linking group.
Such an aromatic group may be a group derived from an aromatic ring selected from hydrocarbon aromatic rings such as benzene, naphthalene, and anthracene. Furan, thiophene, pyrrole, imidazole, 1,2,3- Triazole, 1,2,4-triazole, tetrazole, oxazole, isoxazole, thiazole, isothiazole, thiadiazole, oxadiazole, pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4- It may be a group derived from a heteroaromatic ring selected from heteroaromatic rings such as triazine and 1,2,3-triazine.
Further, these plural rings may be condensed to form a condensed ring such as benzofuran, benzothiophene, indole, indazole, benzoxazole, quinoline, quinazoline, benzimidazole, or benzotriazole. Good.
Of these, the heteroaromatic group is preferably a group derived from a nitrogen-containing aromatic ring.

  These aromatic groups and heteroaromatic groups may further have a substituent. Examples of the substituents that can be introduced include alkyl groups, cycloalkyl groups, alkenyl groups, cycloalkenyl groups, aryl groups, hetero groups. Aryl group, hydroxy group, —SH, carboxylic acid group or alkyl ester thereof, sulfonic acid group or alkyl ester thereof, phosphinic acid group or alkyl ester thereof, amino group, sulfonamido group, amide group, nitro group, halogen atom, or And a substituent formed by bonding a plurality of these, and these substituents may further have the substituents listed here.

Ar ² is preferably a divalent heteroaromatic group which may have a substituent, and more preferably pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4. -A heteroaromatic ring containing a nitrogen atom selected from triazine, 1,2,3-triazine, tetrazole, oxazole, isoxazole, thiazole, isothiazole, thiadiazole, oxadiazole and the like.

Examples of monomers capable of forming a structural unit represented by the following general formula (I) or general formula (II) are shown below [Exemplary monomers (1) to (27)], but the present invention is limited to these. It is not a thing. Among the following exemplary monomers, those having a linking group that is —SO ₂ —NH— from the main chain side [for example, monomer (1)] is a monomer that can be a structural unit represented by the general formula (I), A monomer having a linking group of —NH—SO ₂ — [eg, monomer (12)] is a monomer that can be a structural unit represented by the general formula (II).

The specific acrylic resin is an alkali-soluble polymer containing a structural unit represented by the general formula (I) or the general formula (II), and is represented by the general formula (I) or the general formula (II) included in the specific acrylic resin. The structural unit represented may be only one type, or two or more types may be used in combination.
The content of the structural unit represented by the general formula (I) or the general formula (II) in the specific acrylic resin is preferably 10 mol% to 100 mol%, more preferably 20 mol% to 90 mol%. 30 mol% to 80 mol% is more preferable, and most preferably 30 mol% to 70 mol%.

The specific acrylic resin containing such a structural unit may be a copolymer containing another structural unit in addition to the structural unit represented by the general formula (I) or (II).
Other structural units include structural units derived from hydrophobic monomers having substituents such as alkyl groups and aryl groups in the side chain structure of the monomers, and acidic groups, amide groups, and hydroxy groups in the side chain structure of the monomers. Alternatively, a structural unit derived from a hydrophilic monomer having an ethylene oxide group and the like can be mentioned, and can be appropriately selected depending on the purpose. It needs to be done to the extent not.

  Other copolymer components that can be used in the specific acrylic resin of the present invention include (meth) acrylamide, N-substituted (meth) acrylamide, N-substituted maleimide, (meth) acrylic acid ester, and polyoxyethylene chain (meta). ) Acrylic acid ester, 2-hydroxyethyl (meth) acrylate, styrene, styrene sulfonic acid, o-, p-, or m-vinyl benzene acid, vinyl pyridine, N-vinyl caprolactam, N-vinyl pyrrolidine, (meth) acryl Examples include acid, itaconic acid, maleic acid, glycidyl (meth) acrylate, hydrolyzed vinyl acetate, and vinylphosphonic acid. Among these, preferable copolymerization components include N-benzyl (meth) acrylamide and (meth) acrylic acid.

  The number average molecular weight (Mn) of the specific acrylic resin is preferably in the range of 10,000 to 500,000, more preferably in the range of 10,000 to 200,000, and most preferably in the range of 10,000 to 100,000. The weight average molecular weight (Mw) is preferably in the range of 10,000 to 1,000,000, more preferably in the range of 20,000 to 500,000, and most preferably in the range of 20,000 to 200,000. These molecular weight measuring methods will be described in detail in Examples.

  The structural example of the specific acrylic resin which can be used suitably for this invention is shown below with the combination of each structural unit.

Copolymer (21): A copolymer obtained by replacing the structural unit derived from acrylic acid with a structural unit derived from N- (4-hydroxy-3,5-dimethyl-benzylacrylamide) in the copolymer (15).
In the copolymers (1) to (21), m, n, and o represent the molar ratio of polymerization of the respective structural units, preferably n is 10 mol% to 90 mol%, and m is 5 mol% to 80 mol%, o is 0 mol% to 50 mol%, and m + n + o = 100.
Specific examples of the specific acrylic resin according to the present invention are shown below depending on the raw material monomer [monomer for copolymer (1) to monomer for copolymer (8)] and the polymerization molar ratio thereof. It is not limited. In addition, the specific acrylic resin based on this invention comprised from these monomers is respectively called [specific acrylic resin (1)-specific acrylic resin (8)].

Monomer for copolymer (8) Illustrative monomer (1) / N- (4-hydroxy-3,5-dimethyl-benzylacrylamide) / N-benzylmaleimide monomer ratio (mol%): 33.8 / 35/31. 2

  (B) The specific acrylic resin is preferably used in an addition amount of 1 to 99% by mass with respect to the total solid content in the positive recording layer closest to the support. It is more preferably used in an addition amount, and most preferably in an addition amount of 10% by mass to 50% by mass. When the added amount of the specific polymer is 10% by mass or more, the chemical resistance of the positive recording layer is excellent, and when it is 50% by mass or less, both durability and residue dispersibility in the developer are excellent.

  In the positive recording layer closest to the support in the present invention, the (A) alkali-soluble polyurethane having an acid group and (B) the structural unit represented by the general formula (I) and the general formula ( II) It is necessary to contain two types of (meth) acrylic resins having at least one repeating unit selected from the structural units represented by the structural unit represented by (A): Specific polyurethane: (B) The mass ratio of the specific acrylic resin is preferably 95: 5 to 30:70, more preferably 90:10 to 60:40.

  The components of the lithographic printing plate precursor according to the invention will be described in more detail. First, the positive recording layer will be described. The positive recording layer according to the present invention has two or more recording layers containing a water-insoluble and alkali-soluble polymer compound (referred to as an alkali-soluble resin in this specification as appropriate). At least one layer further contains an infrared absorber (that is, a compound that forms an interaction with a water-insoluble and alkali-soluble resin to suppress the alkali solubility). A positive recording layer containing an infrared absorber and an alkali-soluble resin eliminates the ability to suppress dissolution due to the interaction between the alkali-soluble resin and the infrared absorber in the exposed area by infrared laser exposure, and increases the solubility in an alkali developer. Thus, an image is formed.

In the present invention, the alkali-soluble resin used in a plurality of recording layers includes homopolymers containing these acidic groups in the main chain and / or side chain in the polymer, copolymers thereof, or mixtures thereof. To do. Therefore, the polymer layer according to the present invention has a property of dissolving when contacted with an alkaline developer.
The lower recording layer in the planographic printing plate precursor of the present invention contains the above-described (A) specific polyurethane and (B) specific acrylic resin as essential components as alkali-soluble polymers. An alkali-soluble polymer other than the (A) resin and (B) resin to be described may be included within a range not impairing the effects of the present invention.

[Other alkali-soluble polymers]
An alkali-soluble polymer (hereinafter, appropriately referred to as other alkali-soluble polymer) that is used in another recording layer in the present invention (hereinafter, appropriately referred to as an upper recording layer) and may be included in the lower recording layer as desired. There is no particular limitation as long as it is a conventionally known one, but it is a polymer compound having a functional group in any one of (1) phenolic hydroxyl group, (2) sulfonamide group, and (3) active imide group. It is preferable. For example, the following are exemplified, but not limited thereto. In addition, the following (2) resin having a sulfonamide group included in “other alkali-soluble polymer” is a resin having a structure different from that of the specific acrylic resin (B).

  (1) Examples of the polymer compound having a phenolic hydroxyl group include phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (m-, p Any of-or m- / p-mixing) may be used. Examples thereof include novolak resins such as mixed formaldehyde resins and pyrogallol acetone resins. In addition to this, a polymer compound having a phenolic hydroxyl group in the side chain is preferably used as the polymer compound having a phenolic hydroxyl group. As a polymer compound having a phenolic hydroxyl group in the side chain, a polymerizable monomer comprising a low molecular compound having at least one unsaturated bond polymerizable with the phenolic hydroxyl group is homopolymerized, or other polymerizable property is added to the monomer. Examples thereof include a polymer compound obtained by copolymerizing monomers.

  Examples of the polymerizable monomer having a phenolic hydroxyl group include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, and hydroxystyrene having a phenolic hydroxyl group. Specifically, N- (2-hydroxyphenyl) acrylamide, N- (3-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) acrylamide, N- (2-hydroxyphenyl) methacrylamide, N- (3 -Hydroxyphenyl) methacrylamide, N- (4-hydroxyphenyl) methacrylamide, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, o-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p- Hydroxyphenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (2-hydroxyphenyl) ethyl acrylate, 2- (3-hydroxyphenyl) Preferred are ethyl acrylate, 2- (4-hydroxyphenyl) ethyl acrylate, 2- (2-hydroxyphenyl) ethyl methacrylate, 2- (3-hydroxyphenyl) ethyl methacrylate, 2- (4-hydroxyphenyl) ethyl methacrylate, and the like. Can be used. Furthermore, as described in US Pat. No. 4,123,279, phenol and formaldehyde having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin. A condensation polymer may be used in combination.

(2) Examples of the alkali-soluble polymer compound having a sulfonamide group include a polymer compound obtained by homopolymerizing a polymerizable monomer having a sulfonamide group or copolymerizing the monomer with another polymerizable monomer. (However, the resin containing the structural unit represented by the general formula (I) and the general formula (III) is excluded). The polymerizable monomer having a sulfonamide group includes one or more sulfonamide groups —NH—SO ₂ — in which at least one hydrogen atom is bonded on a nitrogen atom and one or more polymerizable unsaturated bonds in one molecule. And a polymerizable monomer comprising a low molecular weight compound. Among them, a low molecular compound having an acryloyl group, an aryl group, or a vinyloxy group and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group is preferable.

(3) The alkali-soluble polymer compound having an active imide group is preferably one having an active imide group in the molecule. Examples thereof include a polymer compound obtained by homopolymerizing a polymerizable monomer composed of one or more low-molecular compounds or by copolymerizing the monomer with another polymerizable monomer.
As such a compound, specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

  Furthermore, as other alkali-soluble polymer compound in the present invention, two or more of the polymerizable monomer having a phenolic hydroxyl group, the polymerizable monomer having a sulfonamide group, and the polymerizable monomer having an active imide group may be used. It is preferable to use a polymer compound obtained by polymerization, or a polymer compound obtained by copolymerizing two or more kinds of these polymerizable monomers with another polymerizable monomer. When the polymerizable monomer having a phenolic hydroxyl group is copolymerized with a polymerizable monomer having a sulfonamide group and / or a polymerizable monomer having an active imide group, the blending mass ratio of these components is 50:50 to 5: It is preferably in the range of 95, particularly preferably in the range of 40:60 to 10:90.

  In the present invention, the alkali-soluble polymer is a copolymer of a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group, or a polymerizable monomer having an active imide group and another polymerizable monomer. In some cases, from the viewpoint of the effect of improving alkali solubility and development latitude, the monomer imparting alkali solubility is preferably contained in an amount of 10 mol% or more, more preferably 20 mol% or more.

Examples of the monomer component to be copolymerized with the polymerizable monomer having a phenolic hydroxyl group, the polymerizable monomer having a sulfonamide group, or the polymerizable monomer having an active imide group include the compounds listed in the following (m1) to (m12). However, the present invention is not limited to these.
(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, and glycidyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.

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

  The other alkali-soluble polymer preferably has a phenolic hydroxyl group in terms of excellent image-forming properties in exposure with an infrared laser or the like. Further, as the alkali water-soluble polymer compound having a phenolic hydroxyl group, As described in U.S. Pat. No. 4,123,279, phenol and formaldehyde having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin, The condensation polymer of this is mentioned.

As a copolymerization method of the alkaline water-soluble polymer compound, a conventionally known graft copolymerization method, block copolymerization method, random copolymerization method, or the like can be used.
As the alkali-soluble polymer used in the upper recording layer, there is a resin having a phenolic hydroxyl group in that strong hydrogen bonding occurs in the unexposed area, and in the exposed area, some hydrogen bonds are easily released. desirable. More preferred is a novolac resin. A weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000 are preferred.

  Examples of alkali-soluble novolak resins used as other alkali-soluble polymers in the present invention include phenol formaldehyde resins and xylenol cresol formaldehyde resins (3,5-, 2,3-, 2,4-, 2,5- Xylenol), m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (any of m-, p-, m- / p- mixed) mixed formaldehyde resin An alkali-soluble novolak resin such as 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 used. Further, as described in US Pat. No. 4,123,279, condensation of phenol and formaldehyde having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin. You may use a thing together.

  The alkali-soluble novolak resin preferably contains a large amount of novolak resins having a high ortho-position binding property, such as xylenol cresol formaldehyde resin, m-cresol formaldehyde resin, and p-cresol formaldehyde resin. This novolak resin is preferably contained in an amount of 10% by mass or more, more preferably 30% by mass or more in the total novolac resin.

Next, each compound contained in the lower recording layer will be described.
[Acid generator]
The lower recording layer may contain an acid generator that decomposes with light or heat to generate an acid in order to improve the alkali water solubility of the alkali water soluble polymer in the exposed area.
The acid generator means a compound that generates an acid upon irradiation with light having a wavelength of 200 nm to 500 nm or heating at 100 ° C. or higher, and includes a photoinitiator for photocationic polymerization, a photoinitiator for photoradical polymerization, and light from dyes. Examples include known acid generators used in decolorizers, photochromic agents, or microresists, and the like, compounds that generate acids by known thermal decomposition, and mixtures thereof. The acid generated is preferably a strong acid having a pKa of 2 or less, such as sulfonic acid and hydrochloric acid.
Examples of the initiator suitably used in the present invention include triazine compounds described in JP-A-11-95415, and latent Bronsted acids described in JP-A-7-20629. Here, the latent Bronsted acid refers to a precursor that decomposes to produce a Bronsted acid. The Bronsted acid is believed to catalyze the matrix formation reaction between the resole resin and the novolak resin. Typical examples of Bronsted acids suitable for this purpose are trifluoromethanesulfonic acid and hexafluorophosphonic acid.

  Ionic latent Bronsted acids can be preferably used in the present invention. Examples of these include onium salts, especially iodonium, sulfonium, phosphonium, selenonium, diazonium, and arsonium salts. Specific examples of particularly useful onium salts are: diphenyliodonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, phenylmethyl-ortho-cyanobenzylsulfonium trifluoromethanesulfonate, and 2-methoxy-4-aminophenyldiazonium hexafluorophosphate Is included.

Nonionic latent Bronsted acids are also suitably used in the present invention. These examples are compounds represented by the following formula:
RCH ₂ X, RCHX ₂ , RCX ₃ , R (CH ₂ X) ₂ , and R (CH ₂ X) ₃ , where X is Cl, Br, F, or CF ₃ SO ₃ , R is An aromatic group, an aliphatic group or a combination of an aromatic group and an aliphatic group.
Useful ionic latent Bronsted acids are those represented by the following formula:

In the formula, when X is iodine, R ³ and R ⁴ are lone pairs, and R ¹ and R ² are aryl or substituted aryl groups. When X is S or Se, R ⁴ is a lone pair, and R ¹ , R ^2, and R ³ may be an aryl group, a substituted aryl group, an aliphatic group, or a substituted aliphatic group. When X is P or As, then R ⁴ may be an aryl group, a substituted aryl group, an aliphatic group or a substituted aliphatic group. W can be BF ₄ , CF ₃ SO ₃ , SbF ₆ , CCl ₃ CO ₂ , ClO ₄ , AsF ₆ , PF ₆ , or any corresponding acid whose pH is less than 3. Any onium salt described in US Pat. No. 4,708,925 can be used as the latent Bronsted acid of the present invention. These include indonium, sulfonium, phosphonium, bromonium, chloronium, oxysulfoxonium, oxysulfonium, sulfoxonium, selenonium, telluronium and arsonium salts.

  The use of a diazonium salt as the latent Bronsted acid is particularly preferred in the present invention. They provide sensitivities equivalent to other latent Bronsted acids in the infrared region and higher sensitivity in the ultraviolet region.

  In the present invention, these acid generators are 0.01% by mass to 50% by mass, preferably 0.1% by mass, based on the total solid content of the lower recording layer, from the viewpoint of image forming properties and prevention of smearing of non-image areas. -25% by mass, more preferably 0.5% by mass to 20% by mass.

[Infrared absorber]
In the present invention, at least one of the two or more recording layers contains an infrared absorber that is a constituent component that exhibits a photothermal conversion function. This infrared absorber has a function of converting the absorbed infrared rays into heat, and the laser scanning causes the cancellation of the interaction, the decomposition of the development inhibitor, the generation of acid, etc., and the solubility in the developer is greatly increased. . Further, the infrared absorber itself may interact with the alkali-soluble resin to suppress alkali solubility, and the recording layer contains a positive-type recording layer by containing the alkali-soluble resin and the infrared absorber. It becomes.
Such an infrared absorber may be included in the upper recording layer. For example, when an upper recording layer contains an infrared absorber to form a positive recording layer, when the exposed area of the upper recording layer is removed by development, the alkali-soluble resin contained in the exposed lower recording layer is inherently removed. Since the alkali solubility is exhibited and the exposed area is quickly removed, a positive image is formed even when the lower recording layer does not contain an infrared absorber.
In the present embodiment, the lower recording layer may contain an infrared absorber. When the lower recording layer contains an infrared absorber, the infrared absorber is uniformly dispersed in the layer containing (A) the specific polyurethane and (B) the specific acrylic resin that are uniformly mixed, and the interaction It is considered that the releasability is improved or the decomposition property is improved when an acid generator is contained.
The infrared absorber used in the present invention is a dye or pigment that effectively absorbs infrared rays having a wavelength of 760 nm to 1200 nm. A dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm is preferable.

The infrared absorber that can be suitably used for the lithographic printing plate precursor according to the invention will be described in detail below.
As the dye that can be used as the infrared absorber, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

  Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59- 48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc., naphthoquinone dyes, JP-A-58-112792, etc. And squalin dyes described in British Patent 434,875.

  In addition, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also suitable. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A Nos. 58-181051, 58-220143, 59-41363, US Pat. Nos. 59-84248, 59-84249, 59-146063, 59-146061, pyrylium compounds described in JP-A-59-216146, cyanine dyes described in US Pat. No. 4,283,475, the pentamethine thiopyrylium salt and the like, and Japanese Patent Publication Nos. 5-13514 and 5-19702 That pyrylium compounds are also preferably used.

Another example of a preferable dye is a near-infrared absorbing dye described in U.S. Pat. No. 4,756,993 as formulas (I) and (II).
Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and nickel thiolate complexes.

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.

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

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle diameter of the pigment is preferably in the range of 0.01 μm to 10 μm, preferably in the range of 0.05 μm to 1 μm, from the viewpoint of the stability of the recording layer coating liquid and the uniformity of the recording layer to be formed. Is more preferable, and it is particularly preferable to be in the range of 0.1 μm to 1 μm.

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

  Since the lithographic printing plate precursor of the present invention has a positive recording layer, the positive action is caused by the interaction with the binder polymer having a specific functional group (dissolution in the unexposed area is suppressed in an alkaline developer, and It is preferable to use an infrared absorber that causes the dissolution inhibiting action to be released, and in that respect, those having an onium salt structure are particularly preferable. Specifically, among the above-described infrared absorbers, cyanine dyes and pyrylium salts are particularly preferable. The details of the cyanine dye and the pyrylium salt are as described above.

Furthermore, an anionic infrared absorber described in JP-A-11-338131 can also be suitably used. This anionic infrared absorber refers to one having an anion structure without a cation structure in the mother nucleus of a dye that substantially absorbs infrared rays.
For example, (a-1) anionic metal complex and (a-2) anionic phthalocyanine are mentioned.
Here, the (a-1) anionic metal complex refers to an anion that becomes an anion in the central metal and the entire ligand of the complex part that substantially absorbs light.
(A-2) Anionic phthalocyanine refers to a phthalocyanine skeleton having an anion group such as a sulfonic acid, a carboxylic acid, or a phosphonic acid group bonded as a substituent to form an anion as a whole.
Furthermore, an anionic infrared absorber represented by [Ga ⁻ -M-Gb] _m X ^{m +} described in [0014] to [0105] of JP-A-11-338131 [Ga ⁻ represents an anionic substituent, and Gb Represents a neutral substituent. X ^{m +} represents a 1 to m-valent cation containing a proton, and m represents an integer of 1 to 6. Can be mentioned.

  The infrared absorber is preferably a dye, and suitable examples include infrared absorbers having an onium salt structure described in paragraphs [0018] to [0034] of JP-A No. 11-291605.

  For the purpose of further improving the sensitivity and development latitude, the recording layer is used in combination with an infrared absorber that exhibits the ability to suppress dissolution of the above cyanine dyes, pyrylium salts, anionic dyes, and other dyes or pigments. You can also.

  In the present invention, the infrared absorber is 0.01% by mass in the lower recording layer and the other recording layers from the viewpoint of image forming property and suppression of occurrence of contamination in the non-image area with respect to the total solid content of each recording layer. It is preferable to add -50 mass%, More preferably, it is 0.1 mass%-20 mass%, More preferably, it is 0.5 mass%-15 mass%.

  The recording layer of the lithographic printing plate precursor according to the present invention is required not to cause ablation in connection with the infrared laser irradiation apparatus. From the viewpoint of preventing this ablation, in particular, as a polymer material that is a binder contained in another recording layer that is a light receiving surface of an infrared laser, the solubility in alkaline water, that is, an alkaline developer, is changed by application of thermal energy. Any of them can be used, but from the viewpoint of easy availability and difficulty in ablation, it is preferable to use a polymer that is insoluble in water and soluble in alkaline water.

  In addition, as an index of the difficulty of ablation, it is possible to select a polymer having a high ceiling temperature, that is, a temperature at which the rate of the polymerization reaction and the depolymerization reaction becomes equal in a polymerization reaction of a vinyl compound or the like. For simplicity, the decomposition temperature of the polymer can be selected as an index. In the present invention, the polymer constituting the recording layer preferably has a decomposition temperature of 150 ° C. or higher, and more preferably has a decomposition temperature of 200 ° C. or higher. If the decomposition temperature is less than 150 ° C., the possibility of ablation increases, which is not preferable. Components other than the polymer compound contained in the recording layer preferably have a decomposition temperature of 150 ° C. or higher. However, components with a small addition amount include components having a decomposition temperature of less than 150 ° C. as long as they do not cause any problems. Can be used.

  In the positive recording layer of the present invention, various known additives can be used in combination with the above-described constituent components in accordance with the purpose. Of the plurality of recording layers, the lower recording layer needs to contain (A) a specific polyurethane and (B) a specific acrylic resin together with an infrared absorber. Other additives include the lower recording layer and other recording layers. The same layer can be used.

[Other additives]
A fluoropolymer is preferably added to each recording layer of the present invention for the purpose of improving the development resistance of the image area. Examples of the fluorine-containing polymer used in the image recording layer include fluorine-containing monomer copolymers as described in JP-A Nos. 11-288093 and 2000-187318.

  Preferable specific examples of the fluoropolymer include acrylic polymers containing P-1 to P-13 fluorine described in JP-A-11-288093 and A described in JP-A-2000-187318. Examples thereof include fluorine-containing polymers obtained by copolymerizing acrylic monomers having fluorine atoms of −1 to A33 with any acrylic monomer.

  As the molecular weight of the fluorine-containing polymer mentioned above, those having a weight average molecular weight of 2000 or more and a number average molecular weight of 1000 or more are preferably used. More preferably, the weight average molecular weight is 5000 to 300000, and the number average molecular weight is 2000 to 250,000.

  In addition, as the fluorine-containing polymer, a commercially available fluorine-based surfactant that is a compound having the preferred molecular weight can also be used. Specific examples include Megafac F-171, F-173, F-176, F-183, F-184, F-780, and F-781 (all trade names) manufactured by DIC Corporation. .

  These fluorine-containing polymers may be used alone or in combination of two or more. The amount of the fluorine-containing polymer added is required to be 1.4% by mass or more based on the solid content of the image recording layer as a requirement of the present invention. A preferable addition amount is 1.4 to 5.0% by mass. When the amount is less than 1.4% by mass, the effect of improving the development latitude of the image recording layer, which is the purpose of adding the fluorine-containing polymer, cannot be sufficiently obtained. Even if it exceeds 5.0% by mass, the effect of improving the development latitude is not improved. On the other hand, there is a concern that the surface of the image recording layer may become hardly soluble due to the influence of the fluorine-containing polymer and the sensitivity may be lowered.

(Dissolution inhibitor)
If necessary, the lower recording layer or other recording layer in the present invention is thermally decomposable such as an onium salt, an o-quinonediazide compound, an aromatic sulfone compound, an aromatic sulfonic acid ester compound, etc. A substance (dissolution inhibitor) that substantially reduces the solubility of the alkaline water-soluble polymer compound can be used in combination. By adding a dissolution inhibitor, the ability to dissolve the image area into the developer is improved, and by adding this compound, an infrared absorber that does not form an interaction with an alkali-soluble resin should be used. Is also possible. Examples of onium salts include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, and arsonium salts.

  Preferred examples of the onium salt that can be used in the present invention include S.P. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Baletal, Polymer, 21, 423 (1980), diazonium salts described in JP-A-5-158230, US Pat. Nos. 4,069,055, 4,069,056, and JP-A-3-140140 Ammonium salts described in the C. Necker et al., Macromolecules, 17, 2468 (1984), C.I. S. Wenetal, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056; V. Crivello et al., Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, US Pat. Nos. 5,041,358 and 4,491,628, JP-A-2-150848, JP-A-2- An iodonium salt described in 296514,

J. et al. V. Crivello et al., Polymer J .; 17, 73 (1985), J. Am. V. Crivello et al. J. et al. Org. Chem. 43, 3055 (1978); R. Wattal, J. et al. PolymerSci. , Polymer Chem. Ed. , 22, 1789 (1984), J. Am. V. Crivello et al., Polymer Bull. 14, 279 (1985), J. Am. V. Crivello et al., Macromolecules, 14 (5), 1141 (1981), J. MoI. V. Crivello et al. PolymerSci. , Polymer Chem. Ed. 17, 2877 (1979), European Patents 370,693, 233,567, 297,443, 297,442, U.S. Pat. Nos. 4,933,377, 3,902,114 No. 4,491,628, No. 5,041,358, No. 4,760,013, No. 4,734,444, No. 2,833,827, German Patent No. 2,904 The sulfonium salts described in the respective specifications of Nos. 626, 3,604,580 and 3,604,581, V. Crivello et al., Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al. PolymerSci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wenetal, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988).

As a dissolution inhibitor that can be used in the present invention, a diazonium salt is particularly preferable. Particularly suitable diazonium salts include those described in JP-A-5-158230.
The counter ion of the onium salt includes tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfone Examples include acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid. Of these, particularly preferred are alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid.

Suitable quinonediazides include o-quinonediazide compounds. The o-quinonediazide compound used in the present invention is a compound having at least one o-quinonediazide group, which increases alkali solubility by thermal decomposition, and compounds having various structures can be used. That is, o-quinonediazide helps the solubility of the sensitive material system by both the effect of losing the ability to suppress the dissolution of the binder due to thermal decomposition and the change of o-quinonediazide itself into an alkali-soluble substance.
Examples of the o-quinonediazide compound used in the present invention include J. Although the compounds described in pages 339 to 352 of “Light Sensitive Systems” (John Wiley & Sons. Inc.) by Korser can be used, o-reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. Preferred are sulfonic acid esters or sulfonic acid amides of quinonediazide. Further, benzoquinone (1,2) -diazidosulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2 described in US Pat. Nos. 3,046,120 and 3,188,210. ) -Diazide-5-sulfonic acid chloride and phenol-formaldehyde resin are also preferably used.

  Further, esters of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride with phenol formaldehyde resin or cresol-formaldehyde resin, naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and pyrogallol-acetone resin Similarly, the esters are also preferably used. Other useful o-quinonediazide compounds are reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802, JP-A-48-63803, JP-A-48-96575, JP-A-49-38701, JP-A-48. No. 13354, Japanese Patent Publication No. 41-11222, Japanese Patent Publication No. 45-9610, Japanese Patent Publication No. 49-17478, US Pat. No. 2,797,213, No. 3,454,400, 3,544,323, 3,573,917, 3,674,495, 3,785,825, British Patent 1,227,602, In each specification such as 1,251,345, 1,267,005, 1,329,888, 1,330,932, and German Patent 854,890. List what is listed Door can be.

The addition amount of the o-quinonediazide compound is preferably in the range of 1 to 50% by mass, more preferably 5 to 30% by mass, particularly preferably 10 to 30% by mass, based on the total solid content of each recording layer. It is. These compounds can be used alone, but may be used as a mixture of several kinds.
The amount of additives other than the o-quinonediazide compound is preferably 1% by mass to 50% by mass, more preferably 5% by mass to 30% by mass, and particularly preferably 10% by mass to 30% by mass.
In the present invention, the additive and the binder are preferably contained in the same layer.

(Cyclic acid anhydrides, phenols, organic acids)
Further, for the purpose of further improving sensitivity, cyclic acid anhydrides, phenols, and organic acids can be used in combination. Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endooxy-Δ4-tetrahydrophthalic anhydride described in US Pat. No. 4,115,128, Trachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ′, 4 “-Trihydroxytriphenylmethane, 4,4 ′, 3”, 4 ”-tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane and the like. There are sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphoric acid esters, carboxylic acids and the like, which are described in JP-A-60-88942 and JP-A-2-96755. P-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, Phosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-methoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2 -Dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid, etc. The proportion of the above cyclic acid anhydrides, phenols and organic acids in the printing plate material is 0.05 mass% to 20 mass% is preferable, More preferably, it is 0.1 mass%-5 mass%, Most preferably, it is 0.1 mass%-10 mass%.

(Coloring agent)
For example, a dye having a large absorption in the visible light region can be added to the recording layer in the present invention as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Manufactured by Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI52015), Eisenspiron Blue C-RH ( Hodogaya Chemical Co., Ltd.) and the dyes described in JP-A-62-293247.

  By adding these dyes, the image portion and the non-image portion are clearly distinguished after the image formation, so that it is preferable to add them. The addition amount is preferably in the range of 0.01% by mass to 10% by mass with respect to the total solid content of the recording layer.

(Surfactant)
Further, in the recording layer in the present invention, a nonionic surfactant as described in JP-A-62-251740 and JP-A-3-208514 is used in order to broaden the processing stability against the development conditions. Amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, siloxane-based compounds as described in EP950517, JP-A-11-288093 Polymers containing fluorine monomers as copolymerization components as described can be added.

Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like. Specific examples of the double-sided activator 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.). As the siloxane compound, a block copolymer of dimethylsiloxane and polyalkylene oxide is preferable. Specific examples include DBE-224, DBE-621, DBE-712, DBP- manufactured by Chisso Corp. And polyalkylene oxide-modified silicones such as 732, DBP-534, and Tego Glide 100 manufactured by Tego, Germany.
The proportion of the nonionic surfactant and amphoteric surfactant in the recording layer is preferably 0.05% by mass to 15% by mass, more preferably 0.1% by mass to 5% by mass.

(Bake-out agent)
To the lithographic printing plate precursor according to the invention, a printing-out agent for obtaining a visible image immediately after heating by exposure or a dye or pigment as an image colorant can be added. Typical examples of the printing-out agent include a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt.

  Specifically, for example, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A Nos. 50-36,209 and 53-8128, Trihalomethyl compounds and salts described in JP-A Nos. 53-36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440 Examples of such trihalomethyl compounds include oxazole-based compounds and triazine-based compounds, both of which have excellent temporal stability and give clear printout images. Examples of other photoacid releasing agents include various o-naphthoquinonediazide compounds described in JP-A-55-62444; 2-trihalomethyl-5--5 described in JP-A-55-77742. Examples include aryl-1,3,4-oxadiazole compounds; diazonium salts.

(Plasticizer)
Furthermore, a plasticizer may be added to the recording layer coating liquid in the present invention, if necessary, in order to impart flexibility of the coating film. Examples of the plasticizer include 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 oligomers and polymers are used.

[Preparation method of lithographic printing plate precursor]
Hereinafter, a suitable method for producing the lithographic printing plate precursor according to the invention will be described.
In the present invention, first, a lower recording layer is formed on a hydrophilic support. The lower recording layer is obtained by dissolving and dispersing the above-mentioned (A) specific polyurethane, (B) specific acrylic resin, an infrared absorber used as required, and other constituents in an appropriate coating solvent system. The composition may be prepared, applied and dried.

  Suitable solvents for coating the recording layer include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2. -Propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, toluene, etc. However, it is not limited to this. These solvents are used alone or in combination. The concentration of the above components (total solid content including additives) in the solvent is preferably 1% by mass to 50% by mass.

  In principle, the lower recording layer and the upper recording layer (other recording layers) are preferably formed by separating the two layers.

  As a method of forming the two layers separately, for example, a method using a difference in solvent solubility between the component contained in the lower recording layer and the component contained in the upper recording layer, or coating the upper recording layer Thereafter, a method of rapidly drying and removing the solvent can be used, but the method is not limited thereto. In the latter method, the solvent contained in the upper recording layer should be removed immediately before it has an influence such as dissolving a part of the formed lower recording layer, thereby suppressing the compatibility at the interface between the layers. It is a method.

  As a method of utilizing the difference in solvent solubility between the component contained in the lower recording layer and the component contained in the upper recording layer, the alkali contained in the lower recording layer is applied when the upper recording layer coating liquid is applied. The method of using the solvent which does not melt | dissolve soluble resin is mentioned. Thereby, even if it carries out 2 layer application | coating, it becomes possible to isolate | separate each layer clearly and to make a coating film. For example, as the lower recording layer component, a component insoluble in a solvent such as methyl ethyl ketone, diethyl ketone or 1-methoxy-2-propanol that dissolves the alkali-soluble resin that is the upper recording layer component is selected and contained in the lower recording layer. The lower recording layer is applied and dried using a solvent system that dissolves the components to be dissolved, and then the upper recording layer mainly composed of an alkali-soluble resin is dissolved in methyl ethyl ketone, diethyl ketone, 1-methoxy-2-propanol or the like and applied.・ Two layers are possible by drying.

  When applying a solvent that does not dissolve the alkali-soluble resin contained in the lower recording layer when applying the upper recording layer coating solution, the alkali-soluble contained in the lower recording layer is used as the upper recording layer coating solvent. You may mix and use the solvent which melt | dissolves resin, and the solvent which does not melt | dissolve. By changing the mixing ratio of the two solvents, interlayer mixing between the upper recording layer and the lower recording layer can be arbitrarily controlled. When the ratio of the solvent that dissolves the alkali-soluble resin in the lower recording layer is increased, a part of the lower recording layer is dissolved when the upper recording layer is applied, and after drying, is contained as a particulate component in the upper recording layer, Due to this particulate component, protrusions are formed on the surface of the upper recording layer and scratch resistance is improved. On the other hand, when the lower recording layer component is dissolved into the upper recording layer, the film quality of the lower recording layer is lowered and the chemical resistance tends to be lowered. In this way, by controlling the mixing ratio in consideration of each physical property, various characteristics can be expressed, and further, partial compatibility between layers described later can be caused.

  From the viewpoint of the effect of the present invention, when the above mixed solvent is used as the coating solvent for the upper recording layer, the solvent for dissolving the (A) specific polyurethane or (B) specific acrylic resin contained in the lower recording layer is: From the viewpoint of chemical resistance, it is preferably 80% by mass or less with respect to the total amount of solvent used for coating the upper recording layer, and in the range of 10% by mass to 60% by mass, taking into consideration the scratch resistance. Preferably there is.

Next, after applying the second layer (upper recording layer), as a method of drying the solvent very quickly, a method of blowing high-pressure air from a slit nozzle installed substantially perpendicular to the running direction of the web, steam, etc. The method of giving thermal energy as conduction heat from the lower surface of a web from the roll (heating roll) supplied inside is mentioned, or the method of combining them.
Various methods can be used as a method for applying each layer such as a recording layer in the present invention. For example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, Examples thereof include roll coating.
In particular, in order to prevent damage to the lower recording layer when the upper recording layer is applied, the upper recording 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 apply by forward driving to prevent damage to the lower recording layer. .

Coating amount after drying of the lower recording layer of the lithographic printing plate precursor of the present invention, the range of view of developing discriminator improvement in development and printing durability ensuring, of 0.5g / m ² ~2.0g / m ² preferably in the, more preferably in the range of ^{0.7g / m 2 ~1.5g / m 2} .

The coating amount after drying of other recording layer (upper recording layer) is preferably in the range of ^{0.05g / m 2 ~1.0g / m 2} , more preferably 0.07 g / m ² ~ The range is 0.7 g / m ² . When there are two or more upper recording layers, the preferable coating amount of the upper recording layer is the total coating amount of the plurality of upper recording layers.

  In the coating solution for the lower recording layer or the other recording layer in the present invention, a surfactant for improving the coating property, for example, a fluorine-based surfactant as described in JP-A-62-170950. An agent can be added. A preferable addition amount is 0.01 mass% to 1 mass%, more preferably 0.05 mass% to 0.5 mass%, based on the total solid content of the coating liquid.

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

As the support that can be used in the present invention, a polyester film or an aluminum plate is preferable. Among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10% by mass. Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements. Thus, the composition of the aluminum plate applied to the present invention is not specified, and a conventionally known and publicly available aluminum plate can be used as appropriate. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.
The support used in the present invention requires at least the surface on the recording layer forming side to be hydrophilic, but if it is an aluminum support, the roughened surface is relatively hydrophilic. In particular, the surface hydrophilization treatment need not be performed. In addition, when using any of the above supports, that is, when using an aluminum support, it is preferable to perform an appropriate surface hydrophilization treatment described later from the viewpoint of improving the quality of the printed matter.

When using an aluminum plate as a support, it is preferable to perform surface 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 if desired in order to enhance the water retention and wear resistance of the surface. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, the electrolyte concentration is 1% by mass to 80% by mass solution, the liquid temperature is 5 ° C. to 70 ° C., and the current density is 5 A / day. dm ^{2 to} 60 A / dm ² , voltage 1 V to 100 V, electrolysis time 10 seconds to 5 minutes are suitable. If the amount of the anodized film is less than 1.0 g / m ² , the printing durability will be insufficient, or the non-image area of the lithographic printing plate will be easily scratched. Adhering so-called “scratch stains” are likely to occur.

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

  The lithographic printing plate precursor according to the present invention is formed by laminating at least two layers of a lower recording layer and other recording layers (upper recording layers) on a support. An undercoat layer can be provided between the recording layer and the recording layer.

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

  This organic undercoat layer can be provided by the following method. That is, a method in which water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof is dissolved and applied on an aluminum plate and dried, and water, methanol, ethanol, methyl ethyl ketone, etc. In this method, an aluminum plate is immersed in a solution obtained by dissolving the organic compound in an organic solvent or a mixed solvent thereof to adsorb the compound, and then washed with water and dried to provide an organic undercoat layer. . In the former method, a solution having a concentration of 0.005% by mass to 10% by mass of the organic compound can be applied by various methods. In the latter method, the concentration of the solution is 0.01% by mass to 20% by mass, preferably 0.05% by mass to 5% by mass, and the immersion temperature is 20 ° C. to 90 ° C., preferably 25 ° C. to 50 ° C. The immersion time is 0.1 second to 20 minutes, preferably 2 seconds to 1 minute. The solution used for this can be adjusted to a pH range of 1 to 12 with basic substances such as ammonia, triethylamine, potassium hydroxide, and acidic substances such as hydrochloric acid and phosphoric acid. A yellow dye can also be added to improve the tone reproducibility of the image recording material.

The coverage of the undercoat layer, from the viewpoint of printing ^{durability, 2mg / m 2 ~200mg / m} 2 is is suitable, and preferably from ^{5mg / m 2 ~100mg / m 2} .

The positive lithographic printing plate precursor produced as described above is usually subjected to image exposure and development processing.
In the present invention, it is particularly preferable to perform exposure with a light source having a light emission wavelength from the near infrared region to the infrared region. It is preferable.

  The lithographic printing plate precursor according to the invention is subjected to development treatment with water or an alkali developer after exposure. The development treatment may be performed immediately after the exposure, but a heat treatment may be performed between the exposure step and the development step. When the heat treatment is performed, it is preferable that the conditions be within a range of 60 ° C. to 150 ° C. for 5 seconds to 5 minutes. As the heating method, various conventionally known methods can be used. For example, a method of heating while contacting a recording material with a panel heater or a ceramic heater, a non-contact heating method with a lamp or hot air, and the like can be mentioned. This heat treatment can reduce the laser energy required for recording during laser irradiation.

A conventionally known aqueous alkali solution can be used as the developer and replenisher used in the plate making of the lithographic printing plate precursor according to the invention.
The developer that can be applied to the development processing of the lithographic printing plate precursor according to the invention is a developer having a pH in the range of 9.0 to 14.0, preferably in the range of 12.0 to 13.5. A conventionally known alkaline aqueous solution can be used for the developer (hereinafter referred to as developer including the replenisher). For example, sodium silicate, potassium silicate, tribasic sodium phosphate, tertiary potassium phosphate, tertiary ammonium phosphate, secondary sodium phosphate, secondary potassium phosphate, secondary ammonium phosphate, sodium carbonate, carbonic acid Examples include inorganic alkali salts such as potassium, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium borate, potassium borate, ammonium borate, sodium hydroxide, ammonium hydroxide, potassium hydroxide, and lithium hydroxide. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are listed. These alkaline aqueous solutions may be used individually by 1 type, and may use 2 or more types together.

Further, an alkaline aqueous solution composed of a non-reducing sugar and a base can be used. Non-reducing sugar means a saccharide that does not have a free aldehyde group or ketone group and therefore has no reducing ability. Sugar sugars are classified into sugar alcohols reduced by hydrogenation of sugars. Any of these is preferably used in the present invention.
Examples of trehalose type oligosaccharides include saccharose and trehalose. Examples of glycosides include alkyl glycosides, phenol glycosides, and mustard oil glycosides. Examples of the sugar alcohol include D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit, D, L-talit, durisit and allozulcit. Furthermore, maltitol obtained by hydrogenation of a disaccharide and a reduced form (reduced water candy) obtained by hydrogenation of an oligosaccharide are preferably used. Among these, sugar alcohol and saccharose are particularly preferred non-reducing sugars, and D-sorbite, saccharose, and reduced syrup are particularly preferred because they have a buffering action in an appropriate pH region and are inexpensive.

These non-reducing sugars can be used alone or in combination of two or more thereof, and the proportion of the non-reducing sugar in the developer is preferably 0.1% by mass to 30% by mass, more preferably 1% by mass to 20% by mass. It is.
A conventionally known alkaline agent can be used as the base to be combined with the non-reducing sugar. For example, sodium hydroxide, potassium hydroxide, lithium hydroxide, trisodium phosphate, tripotassium phosphate, triammonium phosphate, disodium phosphate, dipotassium phosphate, diammonium phosphate, sodium carbonate, potassium carbonate, Examples include inorganic alkali agents such as ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium borate, potassium borate, and ammonium borate. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are also used.

  These alkali agents are used alone or in combination of two or more. Among these, sodium hydroxide and potassium hydroxide are preferable. The reason is that the pH can be adjusted in a wide pH range by adjusting the amount added to the non-reducing sugar. Further, trisodium phosphate, sodium carbonate, potassium carbonate and the like are preferable because they themselves have a buffering action.

When developing using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than the developer is added to the developer, so that a large amount of PS can be obtained without replacing the developer in the developer tank for a long time. It is known that plates can be processed. This replenishment method is also preferably applied in the present invention. Various surfactants and organic solvents can be added to the developer and the replenisher as necessary for the purpose of promoting or suppressing developability, dispersing development residue, and improving the ink affinity of the printing plate image area. As the replenisher, one having the same formulation as the developer may be used, or an alkaline aqueous solution having a pH higher than that of the developer may be used.
Preferred surfactants used in the developer and replenisher include anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants. Among these, a surfactant selected from an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant is preferable, and an anionic surfactant is most preferable.
Among anionic surfactants, anionic surfactants having a sulfonate structure, a carboxylate structure, or a phosphate structure are preferable, and an anionic surfactant having a sulfonate and a carboxylate are included. More preferably, it is at least one selected from anionic surfactants, and most preferred is an anionic surfactant containing a sulfonate structure.
Specific examples of such anionic surfactants include coconut fatty acid potassium, alkyl sulfate, alkyl ether sulfate, alkyl sulfonate, alkyl benzene sulfonate, alkyl diphenyl ether disulfonate, alkyl naphthalene sulfonate, and naphthalene sulfonic acid. Formalin condensates, alkyl phosphates, alkyl ether phosphates, lauryl iminodipropionate and the like can be mentioned, and among them, alkyl diphenyl ether disulfonate and lauryl iminodipropionate are preferable.
As an anionic surfactant, you may use a commercial item, for example, Pionein C-158-G (brand name): The product made from Takemoto Yushi, Eleminol MON-2 (brand name): The Sanyo Chemical Industries make, CRAFOL AP261 (Brand name): The product made from COGNIS etc. are mentioned.

  The addition amount of the surfactant in the developer is preferably 0.15% by mass to 10.0% by mass, and preferably 0.50% by mass to 5.0% by mass as the solid content with respect to the total amount of the developer. More preferably. When the amount of the surfactant added is 0.15% by mass or more, the dispersibility of the development residue in the developing tank is deteriorated, and an aggregate of the development residue is formed and adheres to the plate surface to cause stains. Can be effectively suppressed, and the developer resistance of the unexposed area is improved by setting the addition amount to 10.0% by mass or less.

  Furthermore, reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids, and organic carboxylic acids, antifoaming agents, softening water, etc. Agents can also be added. The printing plate developed using the developer and the replenisher is post-treated with a desensitizing solution containing washing water, a rinsing solution containing a surfactant or the like, gum arabic or a starch derivative. When the lithographic printing plate precursor according to the invention is used as a printing plate, these treatments can be used in various combinations as post-treatments.

  In recent years, automatic developing machines for printing plates have been widely used in the plate making and printing industries in order to rationalize and standardize plate making operations. This automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for transporting the printing plate, each processing liquid tank and a spray device, and each pumped up by a pump while transporting the exposed printing plate horizontally. The processing liquid is sprayed from the spray nozzle and developed. In addition, recently, a method is also known in which a printing plate is dipped and conveyed by a submerged guide roll or the like in a processing liquid tank filled with the processing liquid. In such automatic processing, each processing solution can be processed while being supplemented with a replenisher according to the processing amount, operating time, and the like. In addition, a so-called disposable processing method in which processing is performed with a substantially unused processing solution can also be applied.

<Preparation method of lithographic printing plate>
A method for processing a lithographic printing plate precursor according to the present invention will be described.
The lithographic printing plate precursor of the present invention is an exposure step for image exposure, and development in which the exposed lithographic printing plate precursor is developed using an aqueous alkali solution containing 0.5% by mass or more and 5.0% by mass or less of a surfactant. Plate making is performed by a method for producing a lithographic printing plate including the steps in this order.
The developer used here is as described, and as the surfactant, at least one surfactant selected from an anionic surfactant having a sulfonate and an anionic surfactant having a carboxylate is used. It is preferable that it is the alkaline developing solution to contain.

Since the lithographic printing plate precursor of the present invention is excellent in dissolution discretion, a developing solution containing a surfactant is used as the developing step, the solution temperature is 20 ° C. or more and 25 ° C. or less, and the development time is Development can be performed under mild conditions of 5 seconds to 20 seconds.
After the development process, washing treatment, rinsing treatment or the like may be performed.
If there is an unnecessary image portion (for example, a film edge trace of the original image film) on the planographic printing plate obtained after the development processing, the unnecessary image portion is erased. Such erasing is preferably performed by applying an erasing solution as described in, for example, Japanese Patent Publication No. 2-13293 to an unnecessary image portion, leaving it for a predetermined time, and then washing with water. A method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber as described in JP-A-5-174842 can also be used.

The lithographic printing plate obtained as described above can be subjected to a printing process after applying a desensitized gum if desired. However, if it is desired to obtain a lithographic printing plate with higher printing durability, Processing is performed.
In the case of burning a lithographic printing plate, before burning, an adjustment as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 is used. It is preferable to treat with a surface liquid.
As its method, with a sponge or absorbent cotton soaked with the surface-adjusting liquid, it is applied onto a lithographic printing plate, or a method in which the printing plate is immersed and applied in a vat filled with the surface-adjusting liquid, Application by an automatic coater is applied. Further, it is more preferable to make the coating amount uniform with a squeegee or a squeegee roller after coating.

In general, the amount of surface-adjusting solution applied is suitably from 0.03 g / m ^{2 to} 0.8 g / m ² (dry mass). The lithographic printing plate coated with the surface-adjusting solution is dried if necessary, and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). The The heating temperature and time in this case depend on the type of components forming the image, but are preferably in the range of 180 ° C. to 300 ° C. for 1 minute to 20 minutes.
The lithographic printing plate precursor according to the invention is subjected to a burning process after plate making, whereby the strength of the recording layer is improved and a higher printing durability is realized.
The burned lithographic printing plate can be appropriately subjected to known treatments such as washing and gumming as necessary, but when a surface-conditioning solution containing a water-soluble polymer compound or the like is used. Can omit so-called desensitizing treatment such as gumming.
The planographic printing plate obtained by such a production method is applied to an offset printing machine or the like and used for printing a large number of sheets.

  EXAMPLES Hereinafter, although this invention is demonstrated according to an Example, the scope of the present invention is not limited to these Examples.

[Obtaining Monomers Used for Specific Acrylic Resins]
Exemplary monomer (1), exemplary monomer (2), exemplary monomer (8), exemplary monomer (9) and exemplary monomer (13) constituting the specific acrylic resin of the present invention are described in Hofmann et al., Markromoleculare Cheme, No. 177. Volume, P1791-1813 (1976), and those skilled in the art can easily obtain similar monomers by selecting several different starting materials.
[Synthesis of Exemplified Monomer (11)]
The exemplified monomer (11) can be synthesized by a method similar to the method described in Kang and Bae, Journal of Controlled Release, Vol. 80, P145-155. A detailed synthesis method is as follows.
10 g (35.6 mmol) of 4-amino-N- (6-methoxy-3-pyridazinyl) -benzosulfonamide was dispersed and dissolved in 120 ml of acetonitrile. To this solution was added a solution of 1.42 g (35.6 mmol) of sodium hydroxide in 30 ml of water, and the reaction mixture was cooled to -10 ° C. 3.7 g (35.6 mmol) of methacrylic acid chloride was added to the resulting reaction mixture. The reaction was continued in the vessel at room temperature for 1 hour. 2,6-Di-tert-butyl-4-methylphenol (BHT) 10 mg was added and the mixture was dried at normal pressure. The oily residue obtained was dissolved in a mixture of 150 ml of methylene chloride and 100 ml of 2N HCl. Methylene chloride was separated by 50 ml 520 ml 2N HCl and 100 ml water, dried over MgSO ₄ and refluxed at normal pressure. The synthesized product was purified by column chromatography to obtain 2.39 g of exemplified monomer (11) (yield: 19%).

[Synthesis of Illustrative Monomer (4)]
Exemplified monomer (4) can be synthesized in the same manner as Exemplified monomer (11) except that acryloyl chloride is used instead of methacryloyl chloride.
24.9 g (89.5 mmol) of 4-amino-N- (2,6-dimethyl-4-pyrimidinyl) -benzosulfonamide was dispersed and dissolved in 500 ml of acetonitrile. To this solution was added a solution of 8.10 g (89.5 mmol) of potassium hydroxide in 75 ml of water, and the reaction mixture was cooled to 0 ° C. The reaction was continued for 14 hours at room temperature in a container. A small amount of precipitate was obtained and collected by filtration. 25 mg of BHT was added and the mixture was dried at normal pressure. The obtained residue was dissolved in 350 ml of refluxed methanol. After cooling to room temperature, the methanol solution was added to 1.6 liters of a 1: 1 mixture of hexane and methyl-t-butyl ester. The compound obtained by filtering and drying this was purified by column chromatography to obtain Illustrative Monomer (4).

[Synthesis of Exemplified Monomer (10)]
1. Synthesis of Intermediate 4-Amino-N-2-pyridylbenzenesulfonamide 288.75 g (1.21 mol) of 4-acetamino-benzosulfonyl chloride and 113.8 g (1.21 mol) of 2-aminopyrididine Dispersed and dissolved in 1350 ml of acetonitrile. 105.2 g (1.33 mol) of pyridine was added over 5 minutes, and the mixture was heated to 60 ° C. The reaction was continued at 60 ° C. for 2 hours. After cooling, N- [4-[(2-pyrimidinylamino) sulfonyl] phenyl] acetamide partially precipitated from the intermediate and was collected by filtration. The second adult product was isolated by vacuum filtration and evaporation, and the resulting composition was treated with 1500 ml of ice water. The second product was treated with 1500 ml of 40 ° C. water. N- [4-[(2-pyrimidinylamino) sulfonyl] phenyl] acetamide was collected by filtration. The obtained N- [4-[(2-pyrimidinylamino) sulfonyl] phenyl] acetamide was 155.9 g (yield: 55%).

  The isolated N- [4-[(2-pyrimidinylamino) sulfonyl] phenyl] acetamide was dissolved in 2.5 liters of a 1: 1 mixture of ethanol and 1-methoxy-2-propanol. Thereafter, 105 g (2.66 mol) of an aqueous solution of sodium hydroxide was added, and the mixture was refluxed for 1 hour. The mixture was cooled to room temperature and the solvent was removed under reduced pressure. The reaction product was dissolved in 1300 ml of water and concentrated hydrochloric acid was added to adjust the pH to 1. The mixture was cooled to 0 ° C. Insoluble material was removed by filtration. The aqueous phase was extracted 3 times with 450 ml of methylene chloride. The aqueous phase was adjusted to neutral pH 7 with 10N sodium hydroxide solution. Since the intermediate 4-amino-N-2-pyrimidylbenzenesulfonamide precipitated, the filter paper was dried. In this way, 93.4 g of the intermediate 4-amino-N-2-pyrimidylbenzenesulfonamide was obtained. (Yield: 70.7%)

2. Synthesis of Exemplified Monomer 10 To 24.9 g (0.1 mol) of the obtained 4-amino-N-2-pyrimidylbenzenesulfonamide, 0.25 g of BHT dissolved in 400 ml of pyridine was added, and the mixture was brought to 0 ° C. Cooled down. 12.54 g (0.12 mol) of methacryloyl chloride was added dropwise. The reaction was continued for 1 hour at temperature conditions 0-5 ° C. Thereafter, the reaction was continued overnight at room temperature. The solvent was removed under reduced pressure and the product was added into an ethanol / water 1: 1 mixture.
The crude product was collected by filtration and dried. The obtained residue was refluxed in a 1: 1 mixture of acetone / water, and this was repeated twice, followed by filtration and drying. 16.3 g of exemplary monomer (10) was obtained. (Yield: 49%)
The exemplified monomers (5), (6) and (7) can also be synthesized by a similar scheme.

<Synthesis of specific acrylic resin (1)>
In a reaction vessel having a volume of 250 ml, exemplary monomer (1) having 160 mmol of sulfonamide group, 20.6 g (132 mmol) of benzylacrylamide, 2.31 g (32 mmol) of acrylic acid and 104 g of γ-butyrolactone were added. In addition, the mixture was heated to 140 ° C. with stirring at 200 rpm. This reaction was carried out under nitrogen reflux. After the solid matter was dissolved, the temperature of the reaction vessel was lowered to 100 ° C. A solution prepared by dissolving 0.37 ml of Trigonox DC50 (manufactured by AKZO NOBEL) and 1.48 ml of Trigonox 141 (manufactured by AKZO NOBEL) in 3.66 ml of butyrolactone was sequentially added. After the reaction started, the reaction vessel temperature was set to 143 ° C., and 50.87 ml of Trigonox DC was added over 2 hours. The reaction mixture was reacted at 140 ° C. for 2 hours while stirring at 400 rpm. The reaction mixture was cooled to 120 ° C., and the stirring condition was increased to 500 rpm. 86.8 ml of 1-methyl-2-propanol was added and the temperature was lowered to room temperature to obtain a specific acrylic resin (1).
The structure of the polymer was confirmed by 1H-NMR spectroscopy and size exclusion chromatography using dimethylacetamide / 0.21% LiCl as a mark in a mixed column in terms of polystyrene.
The molecular weights of specific acrylic resin (1) were Mn: 20500, Mw: 66000, PD: 3.05. In the present specification, “PD” means polydispersity.

<Synthesis of Specific Acrylic Resin (2), (4), (5) and (6)>
In the following synthesis method, the specific acrylic resin (2) is the specific monomer (1), the specific acrylic resin (4) is the exemplary monomer (3), and the specific acrylic resin (5) is the specific monomer (7). (6) uses exemplified monomer (5) as a raw material.
In a reaction vessel having a capacity of 250 ml, 162 mmol of the raw material monomer, 21.3 g (132 mmol) of benzylacetamide, 0.43 g (6 mmol) of acrylic acid and 103 g of γ-butyrolactone were added and stirred at 200 rpm. The mixture was heated to 140 ° C. This reaction was carried out under nitrogen reflux. After the solid matter was dissolved, the temperature of the reaction vessel was lowered to 100 ° C. A solution prepared by dissolving 0.35 ml of Trigonox DC50 (manufactured by AKZO NOBEL) and 1.39 ml of Trigonox 141 (manufactured by AKZO NOBEL) in 3.43 ml of butyrolactone was sequentially added. After the reaction started, the reaction vessel temperature was 140 ° C., and 1.75 ml of Trigonox DC50 was added over 2 hours. The reaction mixture was reacted at 145 ° C. for 2 hours while stirring at 400 rpm. The reaction mixture was cooled to 120 ° C., and the stirring condition was increased to 500 rpm. 85.7 ml of 1-methyl-2-propanol was added, and the temperature was lowered to room temperature to obtain a specific acrylic resin (2), (4), (5) or (6).
The structure of the polymer was confirmed to be the same as that of the specific acrylic resin (1). The results are shown below.
Specific acrylic resin (2) Mn: 28000, Mw: 66000, PD: 2.84
Specific acrylic resin (4) Mn: 34000, Mw: 162000, PD: 4.76
Specific acrylic resin (5) Mn: 22000, Mw: 44000, PD: 1.91
Specific acrylic resin (6) Mn: 23500, Mw: 55000, PD: 2.24

<Synthesis of specific acrylic resins (3) and (7)>
In the following synthesis method, the specific acrylic resin (3) uses the exemplified monomer (1), and the specific acrylic resin (7) uses the exemplified monomer (8) as raw materials.
In a reaction vessel having a capacity of 250 ml, 132 mmol of the raw material monomer, 25.0 g (160 mmol) of benzylacetamide, 2.31 g (32 mmol) of acrylic acid and 104 g of γ-butyrolactone were added and stirred at 200 rpm. The mixture was heated to 140 ° C. This reaction was carried out under nitrogen reflux. After the solid matter was dissolved, the temperature of the reaction vessel was lowered to 100 ° C. A solution prepared by dissolving 0.37 ml of Trigonox DC50 (manufactured by AKZO NOBEL) and 1.87 ml of Trigonox 141 (manufactured by AKZO NOBEL) in 3.43 ml of butyrolactone was sequentially added. After the reaction started, the reaction vessel temperature was 140 ° C. and 1.48 ml of Trigonox DC50 was added over 2 hours. The reaction mixture was reacted at 140 ° C. for 2 hours while stirring at 400 rpm. The reaction mixture was cooled to 120 ° C., and the stirring condition was increased to 500 rpm. 86.8 ml of 1-methyl-2-propanol was added, and the temperature was lowered to room temperature to obtain a specific acrylic resin (3) or (7).
The structure of the polymer was confirmed to be the same as that of the specific acrylic resin (1). The results are shown below.
Specific acrylic resin (3) Mn: 30000, Mw: 85000, PD: 2.78
Specific acrylic resin (7) Mn: 17000, Mw: 29000, PD: 1.67

[Preparation of lithographic printing plate precursors 1 to 38 (invention product) and lithographic printing plate precursors 39 to 44 (comparative product)]
<Production of support>
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.014 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: Containing 0.03% by mass, the balance is prepared using Al and an inevitable impurity aluminum alloy, and after performing the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Produced. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, it was kept soaked at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Further, after heat treatment was performed at 500 ° C. using a continuous annealing machine, an aluminum plate having a thickness of 0.24 mm was finished by cold rolling. After making this aluminum plate width 1030mm, it used for the surface treatment shown below.

-Surface treatment-
The surface treatment was performed by continuously performing the following various treatments (a) to (j). In addition, after each process and water washing, the liquid was drained with the nip roller.

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

(B) Etching treatment with alkali agent The aluminum plate obtained above is subjected to an etching treatment by spraying using an aqueous solution having a caustic soda concentration of 2.6 mass%, an aluminum ion concentration of 6.5 mass%, and a temperature of 70 ° C. 10 g / m ^{2 was} dissolved. Then, water washing by spraying was performed.

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

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10.5 g / L aqueous solution of nitric acid (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions) at a liquid temperature of 80 ° C. The AC power supply waveform is the waveform shown in FIG. 1. The time TP until the current value reaches the peak from zero is 0.8 msec, the duty ratio is 1: 1, and a trapezoidal rectangular wave AC is used with the carbon electrode as the counter electrode. An electrochemical roughening treatment was performed. Ferrite was used for the auxiliary anode. The electrolytic cell used was the one shown in FIG.
The electrolytic cell (radial cell) shown in FIG. 2 includes a main electrolytic cell 40 including a radial drum roller 12 and main electrodes 13a and 13b, an auxiliary anode cell 50 including an auxiliary anode 18, thyristors 19a and 19b, and an AC power source. 20 and. In the main electrolytic cell 40, the electrolytic treatment liquid 14 is supplied to the aluminum plate 11 conveyed to the electrolytic solution passage 17 through the electrolytic solution supply ports 15 and 16.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Then, water washing by spraying was performed.

(E) Alkaline etching treatment An aluminum plate is subjected to an etching treatment by spraying at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% to dissolve the aluminum plate by 0.20 g / m ^2. The smut component mainly composed of aluminum hydroxide generated when the electrochemical surface roughening process is performed using the alternating current of the previous stage is removed, and the edge portion of the generated pit is melted to smooth the edge portion. I made it. Then, water washing by spraying was performed.

(F) Desmutting treatment Desmutting treatment was carried out by spraying with a 25% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

(G) Anodizing treatment Anodizing device of two-stage feeding electrolytic treatment method (first and second electrolytic section length 6 m each, first and second feeding section length 3 m each, first and second feeding electrode length 2.4 m each) Anodizing was performed using this. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 170 g / L (containing 0.5 mass% of aluminum ions) and a temperature of 43 ° C. Then, water washing by spraying was performed. The final oxide film amount was 2.7 g / m ² .

(H) Alkali metal silicate treatment An aluminum support obtained by anodizing treatment was immersed in a treatment layer of a 1% by weight aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C. for 10 seconds to immerse the alkali metal silica. Acid salt treatment (silicate treatment) was performed. Then, water washing by spraying was performed.

(I) Formation of undercoat layer 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. Formed. The coating amount of the coating film (undercoat layer) after drying was 15 mg / m ² .

-Undercoat liquid composition-
・ The following polymer compound 1 0.3g
・ Methanol 100g
・ Water 1g

(Ii) Formation of positive recording layer The following coating solution for the lower recording layer was applied to the obtained support so that the coating amount was 0.85 g / m ^2, and then manufactured by TABIAI, PERFECT OVEN PH200. The Wind Control was set to 7 and dried at 140 ° C. for 50 seconds. After that, the upper recording layer coating solution was applied so that the coating amount was 0.15 g / m ^2, and then dried at 120 ° C. for 1 minute. Lithographic printing plate precursors 1 to 44 were obtained. The lithographic printing plate precursors 1 to 38 are lithographic printing plate precursors of Examples, and the lithographic printing plate precursors 39 to 44 are comparative examples.

[Coating liquid for lower recording layer]
・ Alkali-soluble resin (compounds listed in Table 3, content ratio *) 2.15 g
・ Cyanine dye A 0.13g
・ 4,4′-bishydroxyphenylsulfone 0.11 g
・ Tetrahydrophthalic anhydride 0.15g
・ P-Toluenesulfonic acid 0.01g
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.03 g
・ Crystal violet counter anion
0.10g changed to naphthalenesulfonic acid
・ Fluorosurfactant F-780-F (manufactured by DIC Corporation) 0.035 g
・ Methyl ethyl ketone 24g
・ 13g 2-methoxy-1-propanol
・ 14g of γ-butyrolactone
* Alkali-soluble resin is (A) specific polyurethane described in Table 3, (B) specific acrylic resin, and (C) other alkali-soluble resin, the content ratio described in Table 3 (mass with 100% total resin mass) Ratio) and the total content is 2.15 g.

[Coating liquid for upper recording layer]
・ M, p-cresol novolak 0.2846g
(M / p ratio = 6/4, weight average molecular weight 4500, containing unreacted cresol 0.8% by mass)
・ Cyanine dye A (the above structure) 0.075 g
・ Behenamide 0.060g
-Fluorosurfactant (Surface improving surfactant) 0.022g
[Megafuck F781F, manufactured by DIC Corporation]
・ Image formation improved fluorosurfactant 0.120g
[Megafuck F780 (30%), manufactured by DIC Corporation]
・ Methyl ethyl ketone 15.1g
-1-methoxy-2-propanol 7.7g

The details of each polymer listed in Table 3 are as follows.
(A) Specific polyurethane: Specific polyurethane shown in Tables 1 and 2 (B) Specific acrylic resins (1) to (7): Specific acrylic resins synthesized as described above (other alkali-soluble polymers)
N-1: m-cresol / p-cresol novolak (60/40: weight average molecular weight 3,500)
N-2: phenol / m-cresol / p-cresol novolak (20/50/30, weight average molecular weight 5,000)
(Comparison alkali-soluble polymer)
PR: polymer having the following structure

[Evaluation of lithographic printing plate precursor]
The lithographic printing plate precursor 1 to the lithographic printing plate precursor 38 (lithographic printing plate precursor in the example) and the lithographic printing plate precursor 39 to lithographic printing plate precursor 44 (the lithographic printing plate precursor in comparative example) are respectively shown in Tables 5 to 5 below. The following lithographic printing plate masters and lithographic printing plate preparation methods were evaluated using the developer shown in No. 7 and the following lithographic printing plate preparation methods were performed.
The results are shown in Tables 5 to 7 below.
1. Evaluation of Unexposed Area Retention Time The obtained lithographic printing plate precursor was immersed in a developing bath charged with each developer containing the surfactant listed in Table 4 at different times. The immersion time at which the image density was 95% of that of the developer not immersed was defined as the unexposed portion retention time.
2. Exposure section development time A lithographic printing plate precursor was drawn with a Trend setter manufactured by Creo at a beam intensity of 9 w and a drum rotation speed of 150 rpm. Then, it immersed in the developing bath which prepared each developing solution of a table | surface for changing time. The immersion time at which the image density was equivalent to the image density of the Al support was taken as the exposure part development time.

3. Evaluation of printing durability A test pattern was drawn on a planographic printing plate precursor on a Trend setter manufactured by Creo at a beam intensity of 9 w and a drum rotation speed of 150 rpm. Thereafter, development was performed at a development temperature of 30 ° C. and a development time of 12 seconds using a PS processor LP940H manufactured by Fuji Photo Film Co., Ltd. in which each developer was charged. This was continuously printed using a printer Lithron manufactured by Komori Corporation. At this time, the number of sheets that can be printed while maintaining a sufficient ink density was measured visually to evaluate the printing durability. The printing durability was shown as a relative value when the printing durability of Comparative Example 1 was 1.0.

4). Evaluation of printing durability after burning treatment After rinsing the plate surface of a lithographic printing plate obtained by developing in the same manner as in the evaluation of printing durability, after wiping with a burning surface-conditioning solution BC-7 manufactured by FUJIFILM Corporation Burning was performed at about 230 ° C. for 4 minutes. Then, it washed with water and processed the plate surface with the liquid which diluted the volume FP-2W made from Fuji Film Co., Ltd. with water twice. After that, as in the evaluation of printing durability, printing was performed using a DIC-GEOS (N) black ink manufactured by DIC with a Lithlon printer manufactured by Komori Corporation. The printing durability after the burning treatment was evaluated based on the number of printed sheets at the time when it was recognized. The printing durability was shown as a relative value when the printing durability of Comparative Example 1 was 1.0.

5. Evaluation of UV ink resistance The plate surface of a lithographic printing plate obtained by developing in the same manner as in the evaluation of printing durability was applied to UV ink (Best Cure 161) using a printing machine (Mitsubishi Dia, 1F-2 (trade name)). The product was continuously printed using a trade name, manufactured by Toka Dye Co., Ltd. At this time, the UV ink printing durability was evaluated according to the same evaluation criteria as in “3. Evaluation of printing durability”.

6). Evaluation of residue in developing solution Various developing solutions obtained by treating a lithographic printing plate precursor with 10 m ² per liter are allowed to stand at room temperature (20 to 25 ° C.) for 1 month, and then microfilter FM manufactured by FUJIFILM Corporation. Vacuum filtration was performed using 45 μm, 0.8 μm, and 1.2 μm. Thereafter, the residue remaining on the filter was visually evaluated. The judgment criteria are as follows.
AA: No residue was observed even on a 0.45 μm filter.
A: A slight residue was seen on the 0.45 μm filter. No residue was observed on the filter of 0.8 μm or more.
B: Residue was observed on a filter of 0.8 μm or more. No residue was seen on the 1.2 μm filter.
C: Residue was seen on all filters.
It was evaluated that B or more of the above determination was substantially satisfactory.

7). Evaluation of chemical resistance Chemical resistance was evaluated by the following evaluation methods and evaluation criteria using the following test solutions 1 to 3. The results are shown in Tables 5 to 7 below.
-Test solution-
Test solution 1: EMERAL PREMIUM MXEH (manufactured by ANCHOR)
Test solution 2: Allied Meter-X (manufactured by ABC Chemical)
Test solution 3: Prisco 2351 (phosphate-free: manufactured by PRISCO)
-Evaluation method-
On the surface of the recording layer of the resulting lithographic printing plate precursor, 40 μL of each of the test solutions 1 to 3 were dropped at different locations. After 3 minutes, the droplets were wiped from the surface of the recording layer using a cotton pad. The damage of the recording layer caused by the test solution was visually observed and evaluated according to the following evaluation criteria.
-Evaluation criteria-
0: No damage 1: Gloss of recording layer surface changed 2: Small damage occurred in recording layer (thickness decreased)
3: The recording layer was greatly damaged. 4: The recording layer was completely melted.

[Developer]
-Sorbitol (as solid content) 3.9% by mass
・ Potassium hydroxide (as solid content) 1.6% by mass
-Surfactant described in Table 4 (as solid content) x mass%
(Amounts listed in Table 4)
・ Water (94.5-x) mass%
The details of the surfactants listed in Table 4 below are as follows.
・ Pionine C-158-G (trade name: lauryl iminodipropionate, manufactured by Takemoto Yushi)
・ Eleminol MON-2 (trade name: alkyl diphenyl ether disulfonate, manufactured by Sanyo Chemical Industries)
・ Crawol AP261 (trade name: alkyl ether phosphate, manufactured by COGNIS)

As is apparent from Tables 5 to 7, when (A) the alkali-soluble polyurethane having an acid group and (B) the specific acrylic resin according to the present invention are used, the non-exposed part (image part) is resistant to dissolution in the developer. The difference (development discrepancies) between the solubility (unexposed area retention time) and the solubility (exposed area development time) of the exposed area (non-image area) has increased, resulting in high durability (press life) and chemical resistance It was confirmed that it was excellent in both of the properties. Further, the printing durability when UV ink was used was also good.
Further, in Examples 19 to 50 using an alkali-soluble polyurethane having an acid group neutralized with a monovalent basic compound, it was confirmed that the development disc was further expanded and the chemical resistance was improved. It was done. This is presumably because the polarity of the positive photosensitive layer was improved by neutralization with a monovalent basic compound.
On the other hand, as shown in the table, when (A) specific polyurethane and (B) specific acrylic resin were used, it was an unexpected effect that the generation of development residue in the developer was suppressed. This effect was remarkable when an anionic surfactant having a carboxylate or an anionic surfactant having a sulfonate was used as the developer.
On the other hand, (B) Comparative Example 1 containing no specific acrylic resin is inferior in chemical resistance, (A) Comparative Example 2 containing no specific polyurethane is inferior in printing durability, and any lithographic printing plate precursor The generation of development residue could not be suppressed. Moreover, it replaced with (B) specific acrylic resin, and it turned out that the comparative example 3 containing a comparison alkali-soluble polymer has a short unexposed part holding time, and is inferior in both printing durability and chemical resistance.

DESCRIPTION OF SYMBOLS 11 Aluminum plate 12 Radial drum roller 13a, 13b Main electrode 14 Electrolytic process liquid 15 Electrolyte supply port 16 Slit 17 Electrolyte passage 18 Auxiliary anode 19a, 19b Thyristor 20 AC power supply 40 Main electrolytic tank 50 Auxiliary anode tank

Claims (6)

It has two or more recording layers containing an alkali-soluble resin on a surface hydrophilic support, and at least one of the two or more recording layers contains an infrared absorber, and is applied to an aqueous alkali solution by infrared laser exposure. Among the two or more recording layers, the recording layer closest to the support is (A) an alkali-soluble polyurethane having an acid group, and (B) A lithographic plate containing a structural unit represented by general formula (I) and a (meth) acrylic resin having at least one repeating unit selected from the group consisting of structural units represented by general formula (II) below A printing plate master.

In the general formula (I) and general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —N (R ² ) —, wherein R ² represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Ar ¹ and Ar ² each independently represent an aromatic group, and at least one of them is a heteroaromatic group. a and b each independently represents 0 or 1;   The lithographic printing plate precursor as claimed in claim 1, wherein the alkali-soluble polyurethane having an acid group (A) is neutralized with a basic compound.   One or more selected from the group consisting of (A) an alkali-soluble polyurethane having an acid group, (B) a structural unit represented by the following general formula (I), and a structural unit represented by the following general formula (II) The lithographic printing plate precursor according to claim 1 or 2, wherein the content ratio of the (meth) acrylic resin having a repeating unit of 95: 5 to 30:70 in terms of mass ratio. An exposure step for image exposure of the lithographic printing plate precursor according to any one of claims 1 to 3, and
A method for producing a lithographic printing plate comprising, in this order, a development step of developing the exposed lithographic printing plate precursor using an alkaline aqueous solution containing 0.5% by mass or more and 5.0% by mass or less of a surfactant.   The method for preparing a lithographic printing plate according to claim 4, wherein the surfactant is at least one selected from an anionic surfactant having a sulfonate and an anionic surfactant having a carboxylate.   The lithographic printing plate according to claim 4 or 5, wherein the developing step is carried out under the conditions that the liquid temperature of the developing solution is 20 ° C or higher and 25 ° C or lower and the developing time is 5 seconds or longer and 20 seconds or shorter. Manufacturing method.