JP2009175195A - Lithographic printing plate precursor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate precursor excellent in reproducibility of a high-definition image, printing durability and chemical resistance. <P>SOLUTION: The lithographic printing plate precursor has on a support two or more infrared-sensitive positive recording layers each including a resin and an infrared absorber, wherein: of the two or more positive recording layers, a positive recording layer that is nearest to the support includes two or more resins including a polymer having a specific structural unit; at least one of the resins forms a dispersion phase in the layer; and the rate of dissolution with respect to an alkaline aqueous solution of the resin forming the dispersion phase is slower than that of another of the resins forming a matrix phase. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

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

  The positive type lithographic printing plate 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).
Further, from the viewpoint of improving printing durability and solvent resistance in an image area, a method of blending a polymer in the lower layer of a multilayer type recording layer has been proposed (for example, see Patent Document 3).
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, effectively suppressing thermal diffusion to the support and improving the image formation, but forms a recording layer having the multilayer structure as described above. In order to achieve this, it is necessary to select resins having different characteristics as the resins used in the respective layers constituting the recording layer, and the problem that these interactivity decreases or the developability of the lower layer is good. As a result, there is a problem of so-called side edges, in which the lower layer of the unexposed area elutes from the contact interface with the developer during development, and in particular, reproducibility of small area images such as fine lines during high resolution exposure. For the improvements are desired at present.
JP 2001-281856 A European Patent Publication No. 1826001A1 JP-A-2005-242241

  An object of the present invention is to provide a positive type lithographic printing plate precursor excellent in reproducibility of a small area image at the time of high resolution exposure, printing durability and chemical resistance.

  The lithographic printing plate precursor according to the invention has at least two positive recording layers containing a resin and an infrared absorber on the support, and having at least two positive recording layers whose solubility in an alkaline aqueous solution is increased by infrared laser exposure. Among the positive recording layers described above, the positive recording layer closest to the support has at least one of the structural unit represented by the following general formula (I) and the structural unit represented by the following general formula (II). A layer containing two or more kinds of resins including a polymer having the polymer (hereinafter, referred to as “specific polymer” as appropriate), and at least one of the two kinds of resins forms a dispersed phase in the layer. The dissolution rate of the resin forming the dispersed phase in the alkaline aqueous solution is lower than the dissolution rate of the resin forming the matrix phase in the alkaline aqueous solution.

In the general formula (I) and general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —NR 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 further have a substituent.

  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 may have other layers, such as a surface protective layer, an undercoat layer, and a back coat layer, on the support, in addition to the plurality of positive recording layers. Can be provided as long as they are not impaired.

  The dispersed phase formed by the resin in the recording layer may be (1) a combination of a plurality of mutually incompatible resins, or (2) a granular polymer selected from microcapsules and latex in the matrix resin. It can be formed by a method such as dispersing.

Since the lithographic printing plate precursor according to the present invention uses a method that utilizes the change in solubility of the recording layer in alkaline water, the resin used in the positive recording layer contains a water-insoluble and alkaline water-soluble resin. Is a preferred embodiment. In the present invention, from the viewpoint of ease of production, the method (1) of combining a plurality of types of mutually incompatible resins to form a dispersed phase and a matrix phase (dispersion medium) is preferable.
As the plurality of types of resins, resins that are incompatible with each other may be selected, and even if they are uniformly dissolved in the coating solvent, the dispersed phase is changed along with the removal of the solvent when forming the recording layer. It may be formed.

In the present invention, at least one of the resins contained in the lower recording layer needs to be a specific polymer. The specific polymer is preferably used as a resin for forming a matrix phase (dispersion medium).
The resin constituting the dispersed phase in the lower recording layer is preferably one having a slower dissolution rate in an alkaline aqueous solution than the resin constituting the matrix phase. In the present invention, the polymer constituting the dispersed phase can be selected from the resins described in detail later. Among them, the polymer constituting the dispersed phase is particularly preferably a novolak resin.

  As the size of the dispersed phase, it is preferable that the maximum major axis is 0.1 μm to 0.8 μm and the average major axis is 0.05 μm to 0.6 μm. The size of the dispersed phase is the size of the circular or elliptical dispersed phase after a recording layer section obtained by cutting the recording layer with a microtome or the like is made conductive and then photographed with a scanning electron microscope (SEM). Can be evaluated by an image analyzer.

  In the present invention, in the resin matrix phase in the lower recording layer, a dispersed phase whose solubility in an aqueous alkali solution is increased by heat or light is formed, so that in the exposed area, the alkali solubility of the dispersed phase is increased. Since the permeable path of the alkaline aqueous solution is formed in the matrix phase, the dissolution of the alkali-soluble resin matrix phase under the exposed portion is promoted. In the unexposed area (image area), the dispersed phase itself is selected to have a lower solubility in an alkaline aqueous solution than the resin constituting the matrix phase, so that the aqueous alkaline solution penetrates into the resin matrix phase in the lower recording layer. In particular, the penetration of the image area from the heel side (side side) is effectively suppressed, so that the damage of the image area with the alkaline aqueous solution can be suppressed, and further, the image area adheres to the support. Therefore, it is presumed that the image reproducibility is excellent and the printing durability and chemical resistance of the image area are also improved. Furthermore, the specific polymer contained as an essential component in the lower recording layer exhibits excellent dissolution resistance to organic solvents in the recording layer. For this reason, it is presumed that it is difficult to be damaged by a plate cleaner.

  Further, the above-described characteristics relating to the present invention are particularly remarkable in a high-definition image having a small image area. For this reason, the lithographic printing plate precursor of the present invention is used in conjunction with the formation of high-definition images by high-resolution exposure machines such as the PT-R series manufactured by Dainippon Screen and Trendsetter UHR manufactured by KGC, or the recent CTP conversion. It is particularly useful for the formation of high-definition images using an increasing number of FM screens. Commercially available FM screens such as Staccato (trade name: manufactured by KGC), FAIRDOT, Randot (trade names: manufactured by Dainippon Screen) ), Co-Re screen, TAFFETA (trade name: manufactured by Fuji Photo Film) and the like.

  ADVANTAGE OF THE INVENTION According to this invention, the positive type lithographic printing plate precursor excellent in the reproducibility of a high-definition image, printing durability, and chemical resistance can be provided.

  Therefore, according to the present invention, it is possible to improve the plate-making stability particularly when a high-definition image is formed. Furthermore, the printing durability of the high-definition image area is also improved. Note that the high-definition image referred to here also includes FM screen images that are increasingly used with the recent CTP conversion.

Hereinafter, the planographic printing plate precursor according to the invention will be described in detail.
The lithographic printing plate precursor according to the invention has at least two positive recording layers containing a resin and an infrared absorber on a support, and having at least two positive recording layers whose solubility in an alkaline aqueous solution is increased by infrared laser exposure. Of the above positive recording layers, the positive recording layer closest to the support is selected from the structural unit represented by the following general formula (I) and the structural unit represented by the following general formula (II). It is a layer containing two or more kinds of resins including a polymer having a species (specific polymer), and at least one of the two or more resins forms a dispersed phase in the layer to form a dispersed phase. The dissolution rate of the resin in the aqueous alkali solution is slower than the dissolution rate of the resin forming the matrix phase in the aqueous alkaline solution.

In the general formula (I) and general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —NR 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 further have a substituent.

  The dispersed phase in the present invention can be formed in the following manner. That is, (1) a mode in which a dispersed phase is formed in a base material (matrix phase), that is, a dispersion medium, using two or more kinds of resins (polymer compounds) that are not compatible with each other. A dispersed phase composed of a material that is incompatible with the material is formed. In another embodiment, (2) after forming a dispersed phase containing a predetermined component in advance using microcapsules or latex, the dispersed phase is introduced into a polymer binder, that is, a resin matrix phase. . In the dispersed phase, a dissolution inhibitor and an infrared absorber can be added as necessary.

  Regarding the method of forming the dispersed phase, first, the dispersed phase obtained by the method (1) will be described. In the two or more polymer compounds that are not compatible with each other, at least one polymer compound is a polymer that is insoluble in water and soluble in an alkaline aqueous solution, and is preferably a polymer compound that forms a matrix phase. In the present invention, the polymer insoluble in water and soluble in an alkaline aqueous solution is preferably a specific polymer.

  Here, incompatible with each other means that the combination of two or more polymers does not become a single-phase solid or liquid in appearance, and appropriately handles the cross section of the recording layer, It can be confirmed by taking and observing a cross-sectional photograph visually or with a scanning electron microscope.

  Examples of the polymer compound used in combination of two or more kinds of incompatible polymer compounds include urethane polymer compounds, acrylic polymer compounds, styrene polymer compounds, novolak resins, diazo resins, amide polymers. Compounds, polyether compounds, and the like.

  Suitable combinations include acrylic polymer compounds and urethane polymer compounds, acrylic or urethane polymer compounds and diazo resins, novolak resins and urethane polymer compounds, and the like. Furthermore, those containing a urethane polymer compound are preferred from the viewpoint of being hardly damaged during development. In the present invention, a combination of a specific polymer and a novolac resin is particularly preferable.

  When these two or more polymer compounds are used to form the lower recording layer in the presence of an infrared absorber, a dispersed phase is formed in the resin matrix phase, and the infrared absorber is contained in a large amount in the dispersed phase. Will be. When forming a binder layer using two or more kinds of polymer compounds that are not compatible with each other, a polymer that exhibits stronger interaction such as hydrogen bonding and ionicity tends to form a spherical or flat sphere in the binder. Localization as described above indicates that when an infrared absorber is present in the dispersed phase, the infrared absorber is ionic or a coordination complex. This happens because it is easy to be taken in. When an acid generator or a radical generator (polymerization initiator) coexists, the initiator usually has a high polar group such as an onium salt structure, a triazine, a sulfonic acid ester, and the dispersed phase is similar to an infrared absorber. It is easy to be taken in.

  Here, when the lower recording layer is formed using two or more kinds of polymer compounds that are incompatible with each other, when a dispersed phase is formed in the polymer matrix phase as a dispersion medium, this structure is called a sea-island structure. In the present invention, the observation of the sea-island structure is carried out by making a recording layer cross section obtained by cutting a lithographic printing plate precursor with a microtome or the like, then taking a photograph with a scanning electron microscope (SEM), The size of the dispersed phase can be evaluated by an image analyzer. If the image is unclear when photographed, the cross section of the recording layer is processed by, for example, solvent etching according to the method described in “Polymer Alloy and Polymer Blend” (L.A. UTRACKI, translated by Toshio Nishi; Tokyo Chemical Dojin). After shooting, a clearer image can be obtained.

  In such a sea-island structure, the size of the dispersed phase present in the polymer binder phase serving as the dispersion matrix depends on the coating solvent system and the drying conditions after coating, but by controlling these conditions, A dispersed phase having a maximum major axis of 0.8 μm or less, preferably 0.6 μm or less, and an average major axis of 0.6 μm or less, preferably 0.5 μm or less can be formed. In this case, it is preferable that the maximum major axis and the average major axis are small. The lower limit of the size of the dispersed phase particles is not particularly limited, but usually the maximum major axis is about 0.1 μm and the average major axis is about 0.05 μm. The major axis is obtained by image analysis of the dispersed phase particles as described above, and means a diameter when it is a circle and a major axis when it is an ellipse.

  In the present invention, at least one of the resins constituting the lower recording layer needs to be a specific polymer. As described above, the specific polymer in the invention is preferably contained as a resin constituting the resin matrix phase in the lower recording layer.

<Specific polymer>
Hereinafter, the specific polymer will be described in detail.
The specific polymer 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 —NR 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 general formula (I), R ¹ represents a hydrogen atom or an alkyl group, and 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 —NR ² —, preferably —NR ² —. R ² represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted alkynyl group, preferably a hydrogen atom or an unsubstituted alkyl group, Preferably it is a hydrogen atom.

a and b each independently represent 0 or 1, and a preferred embodiment is when a is 0 and b is 1, more preferably when a and b are both 0, 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 NR 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 aromatic groups may be selected from hydrocarbon aromatic rings such as benzene, naphthalene, anthracene, etc., and 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-triazine, 1,2 Or a heteroaromatic ring such as 3-triazine.
Further, these plural rings may be condensed to take a condensed ring form such as benzofuran, benzothiophene, indole, indazole, benzoxazole, quinoline, quinazoline, benzimidazole, or benzotriazole. Good.

  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 an optionally substituted heteroaromatic group, more preferably pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, It is selected from heteroaromatic rings containing nitrogen atoms selected from 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 polymer is an alkali-soluble polymer containing the 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) contained in the specific polymer. Only one type of structural unit may be used, 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) is preferably 10 to 100 mol%, more preferably 20 to 90 mol%, still more preferably 30 to 80 mol%. In some cases, it is preferably 30 to 70 mol%.

The specific polymer 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 a hydrophobic monomer having a substituent such as an alkyl group or an aryl group in the side chain structure of the monomer, an acidic group, an amide group, a hydroxy group or an ethylene oxide group in the side chain structure of the monomer. From these, the monomer species to be copolymerized must be selected within a range that does not impair the alkali solubility of the specific polymer.

  Other copolymer components that can be used in the specific polymer of the present invention include (meth) acrylamide, N-substituted (meth) acrylamide, N-substituted maleimide, (meth) acrylic acid ester, and (oxy) polyoxyethylene chain. 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) acrylic acid , Itaconic acid, maleic acid, glycidyl (meth) acrylate, hydrolyzed vinyl acetate, vinylphosphonic acid and the like. Among these, preferable copolymerization components include N-benzyl (meth) acrylamide and (meth) acrylic acid.

  The number average molecular weight (Mn) of the specific polymer 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.

  Examples of the constitution of specific polymers that can be suitably used in the present invention are shown below by combinations of respective structural units.

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 to 90 mol%, m is 5 to 80 mol%, o is 0 to 50 mol%, and m + n + o = 100.
Although the specific example of the specific polymer which concerns on this invention is shown below with the raw material monomer [copolymerization monomer] and its polymerization molar ratio, this invention is not restrict | limited to these. In addition, the specific polymer which concerns on this invention comprised from these monomers is called [specific polymer (1)-specific polymer (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

  As content of the specific polymer in a lower recording layer, it is preferable that it is 40 mass%-95 mass% in the total solid of a lower recording layer, and it is more preferable that it is 50 mass%-95 mass%.

  When the specific polymer is used as a resin constituting the matrix phase in the lower recording layer, the content ratio of the resin constituting the dispersed phase (specific polymer: resin for dispersed phase) is 95: 5 to 50 by mass ratio. : 50 is preferable, and 90:10 to 60:40 is more preferable.

  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 contains a resin and an infrared absorber (that is, a water-insoluble and alkali-soluble polymer compound and a compound that suppresses alkali solubility thereof), and its ability to suppress dissolution is eliminated by infrared laser exposure. An image is formed by increasing the solubility of the resin.

  In the present invention, a water-insoluble and alkali-soluble polymer compound (hereinafter referred to as an alkali-soluble polymer as appropriate) used for a plurality of positive recording layers is a main chain and / or a side chain in the polymer. Includes a homopolymer containing an acidic group, a copolymer thereof, or a mixture thereof. Therefore, the polymer layer according to the present invention has a property of dissolving when contacted with an alkaline developer. The alkali-soluble polymer contained in the lower recording layer in the present invention includes the specific polymer described above.

  The alkali-soluble polymer used in the lower recording layer and other recording layers (hereinafter, appropriately referred to as the upper recording layer) in the present invention is not particularly limited as long as it is a conventionally known polymer, but (1) phenolic A polymer compound having a functional group of any one of a hydroxyl group, (2) a sulfonamide group, and (3) an active imide group in the molecule is preferable. For example, the following are exemplified, but not limited thereto.

  (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 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. 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. . 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. As the polymer compound, an unsaturated bond polymerizable with an active imide group is contained in one molecule, respectively. 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 the 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 are polymerized. It is preferable to use a polymer compound obtained by copolymerizing other polymerizable monomers with these two or more polymerizable monomers. 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 alkaline water-soluble polymer compound 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 alkaline 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.

Hereinafter, a preferred method for forming the dispersed phase in the lower layer will be described.
In the present invention, the selection of the coating solvent is an important factor for setting the dispersed phase constituting the lower sea island structure to a maximum major axis of 0.8 μm or less and an average major axis of 0.6 μm or less. By using it, it becomes possible to produce a sea-island structure having a desired size.

  Although there is no clear logic for reducing the dispersed phase by selecting a coating solvent system, as coating solvents, ketone systems such as cyclohexanone and methyl ethyl ketone, methanol, ethanol, propanol, 1-methoxy-2-propanol, etc. Alcohol, cellosolve such as ethylene glycol monomethyl ether, lactone such as γ-butyrolactone, sulfoxide such as dimethyl sulfoxide and sulfolane, halogen such as ethylene dichloride, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate Such as acetates, ethers such as dimethoxyethane, esters such as methyl lactate and ethyl lactate, amides such as N, N-dimethoxyacetamide and N, N-dimethylformamide, N-methylpyrrolidone, etc. It is preferable to use loridone, urea such as tetramethylurea, aromatic such as toluene, etc. Among them, methyl ethyl ketone, 1-methoxy-2-propanol, ethylene glycol monomethyl ether, γ-butyrolactone, dimethyl sulfoxide, etc. preferable. These solvents may be used alone or in combination.

  In addition to the coating solvent system described above, the condition for drying the undried coating film after coating with the photosensitive solution is also an important factor in order to obtain a predetermined size of the sea-island structure dispersed phase in the lower recording layer. It is known that For the production of such a sea-island structure, reference can be made to the description in JP-A-9-90610.

  In the case where a polymer matrix phase and a dispersed phase are formed using two or more kinds of polymer compounds that are not compatible with each other, a polymer compound that is suitably used as a resin for forming a dispersed phase is shown below.

  The polymer compound suitably used as the resin forming the dispersed phase in the present invention is a copolymer having a structural unit derived from at least one of monomers corresponding to the following (1) to (5), or Examples thereof include urethane polymer compounds, novolac resins, and polyethers. Among these resins, novolak resin is particularly preferable as the resin forming the dispersed phase.

(1) Acrylamides, methacrylamides, acrylic esters and methacrylic esters having an aromatic hydroxyl group. Specific examples include N- (4-hydroxyphenyl) acrylamide or N- (4-hydroxyphenyl) methacrylamide, o-, p-, m-hydroxyphenyl acrylate or methacrylate, 2-hydroxyethyl methacrylate, and the like. It is done.
(2) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.
(3) A low molecular compound having one or more polymerizable unsaturated bonds and a sulfonamide group having at least one hydrogen atom bonded on a nitrogen atom, for example, the following formulas (i) to (v) ).

In the above formula, X ¹ and X ² each represent —O— or —NR ⁷ —. R ¹ and R ⁴ each represent a hydrogen atom or —CH ₃ . R ² , R ⁵ , R ⁹ , R ¹² and R ¹⁶ each represents an optionally substituted alkylene group having 1 to 12 carbon atoms, a cycloalkylene group, an arylene group or an aralkylene group. R < ³ >, R < ⁷ >, R <^13> represents a hydrogen atom, the C1-C12 alkyl group which may have a substituent, a cycloalkyl group, an aryl group, and an aralkyl group. R ⁶ and R ^{17 each} represents an optionally substituted alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group. R ⁸ , R ¹⁰ and R ¹⁴ each represent a hydrogen atom, a halogen atom or —CH ₃ . R ¹¹ and R ¹⁵ each represents a C 1-12 alkylene group, cycloalkylene group, arylene group or aralkylene group which may have a single bond or a substituent. Y ¹ and Y ² each represent a single bond or —CO—.

  Specific examples include m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) acrylamide and the like.

(4) Low molecular weight compounds each having at least one unsaturated bond polymerizable with an active imino group represented by the following formula (vi) in one molecule, such as N- (p-toluenesulfonyl) methacrylamide, N- (P-toluenesulfonyl) acrylimide and the like.

(5) Styrenic compounds, or vinyl acetate, vinyl alcohol, such as o-, m-, p-hydroxystyrene, p-sulfonic acid styrene, o-, m-, p-carboxylstyrene, and the like.

  Monomers corresponding to the above (1) to (5) may be used singly or in combination of two or more, but further combined with monomers other than the above polymerizable (1) to (5). A copolymer is preferred. In this case, it is preferable to have 10 mol% or more, preferably 20 mol% or more, more preferably 25 mol% or more of structural units derived from the monomers (1) to (5). Such monomers used in combination with the above monomers (1) to (5) are exemplified by the following (6) to (16).

(6) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(7) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl (Substituted) alkyl acrylates such as acrylates.
(8) (Substitution) such as methyl methacrylate, ethyl methacrylate, pyrrole methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate Alkyl methacrylate.

(9) Acrylamide, methacrylamide, N-methylolacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.
(10) 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.

(11) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(12) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene.
(13) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.

(14) Olefins such as ethylene, propylene, isobutylene, butadiene, and isoprene.
(15) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
(16) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

  Furthermore, monomers that can be copolymerized with these monomers may be copolymerized. As these polymer compounds, 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 300,000, the number average molecular weight is 2000 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10.

Water-insoluble and alkaline aqueous-soluble urethane polymer compounds that can be used in the present invention include, for example, JP-A-63-124047, JP-A-63-287946, JP-A-2-866, and JP-A-2. Although the urethane type polymer compound of each gazette of -156241 is mentioned, it is not limited to these.
In the present invention, the above acrylic polymer compound and urethane polymer compound may be used in combination.

  Examples of the alkali-soluble novolak resin used in the present invention include phenol formaldehyde resin, xylenol cresol formaldehyde resin (3,5-, 2,3-, 2,4-, 2,5-xylenol), and 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, etc., alkali-soluble novolak resin Can be mentioned. As these alkali-soluble novolak resins, those having a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000 are 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.

  In the case of the positive recording layer, the lower recording layer composed of the resin matrix phase including the dispersed phase formed in this way has an infrared absorber and a compound whose solubility in an alkaline solution is changed by heat in the dispersed phase. It is contained at a high content and efficiently improves the solubility of the polymer matrix phase in an alkaline solution.

  Next, the dispersed phase (2) in the present invention will be described. In the particulate polymer such as microcapsule and latex that can be used in the present invention, the microcapsule is used in the method described in the examples of JP-A-1-145190 or Sankyo publication "New edition microcapsules-production method, properties, and applications". It can be easily prepared by the method described. As for latex, JP-A-10-265710, JP-A-10-270233, JP-A-2-2281, and publication of the polymer publication “Polymer Latex Chemistry”, New Polymer Library “Polymer Latex” It can be prepared by the latex described in 1.

  In this case, examples of the substance included in the capsule and the substance included in the latex include an initiator such as an acid generator and a radical generator, a photothermal conversion material, and a crosslinking agent. In addition, as the polymer compound that can be used in the polymer matrix phase for forming the layer in the lower layer having the dispersed phase of the mode (2), the same compounds as those described in the mode (1) of the dispersed phase are the same. Can be used for

Next, each compound contained in the dispersed phase will be described.
The dispersed phase may contain an acid generator that decomposes with light or heat to generate an acid in order to improve the alkaline water solubility of the alkaline water-soluble polymer compound in the exposed area.
The acid generator means a compound that generates an acid upon irradiation with light having a wavelength of 200 to 500 nm or heating at 100 ° C. or more, and includes a photoinitiator for photocationic polymerization, a photoinitiator for photoradical polymerization, and light from dyes. Examples thereof include known compounds that generate acid upon thermal decomposition, such as known acid generators used in decolorizers, photochromic agents, or microresists, and the like. 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 , wherein 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 to 50% by mass, preferably 0.1 to 25% by mass, based on the total solid content of the lower recording layer, from the viewpoint of image forming properties and prevention of stains in the non-image area. More preferably, it is added at a ratio of 0.5 to 20% by mass.

The positive recording layer in the present invention contains an infrared absorber, which is a 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. . In addition, the infrared absorber itself may interact with the alkali-soluble resin to suppress alkali solubility.
When such an infrared absorber is contained in the dispersed phase in the lower layer, the infrared absorber will be localized in the dispersed phase, improving the interaction release property, or when an acid generator is contained Is considered to improve its degradability.
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, 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 cyanine dyes described in British Patent 434,875.

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

Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).
Particularly preferred among these dyes 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. 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 In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used.

  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, the anionic infrared absorber described in Japanese Patent Application No. 10-237634 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.
Further, an anionic infrared absorber represented by [Ga ⁻ -M-Gb] _m X ^{m +} described in [0014] to [0105] of Japanese Patent Application No. 10-237634 [Ga ⁻ represents an anionic substituent; 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 absorbing agent is 0.01 to 50 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 in the lower recording layer and other recording layers. It is preferable to add mass%, More preferably, it is 0.1-20 mass%, More preferably, it is 0.5-15 mass%.

  The infrared absorber may be contained in either the matrix phase or the dispersed phase, or may be contained in both. When the latex constituting the dispersed phase as described above contains desired components such as an initiator and an infrared absorber, it may be added together with raw materials when forming latex particles, or may be introduced after forming the latex. .

  Examples of the method of introducing after forming the latex include a method in which desired components such as an initiator, a color system, and a crosslinking agent to be introduced are dissolved in an organic solvent and added to a dispersion medium.

  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 ablation, any polymeric material that is a binder constituting the recording layer can be used as long as the solubility in alkaline water, that is, an alkaline developer is changed by application of thermal energy. 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, it is necessary to form a dispersed phase in the lower recording layer, but the same additives can be used for the lower recording and the other recording layers for the 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. As specific examples, MegaFuck F-171, F-173, F-176, F-183, F-184, F-780, F-781 (all trade names) manufactured by Dainippon Ink & Chemicals, Inc. are used. Can be mentioned.

  These fluorine-containing polymers may be used alone or in combination of two or more. The addition amount is 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.

  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 .; 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, 4,491,628, JP-A-2-150848 and JP-A-2-296514. Iodonium salt,

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 No. 626, No. 3,604,580, No. 3,604,581, sulfonium salts described in J.P. V. Crivello et al., Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al. 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) -diazide- described in U.S. Pat. Nos. 3,046,120 and 3,188,210. Esters of 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-48-13354, Japanese Patent Publication Nos. 41-11222, 45-9610, 49-17474, U.S. Pat. Nos. 2,797,213, 3,454,400, 3,544,323, 3,573,917, 3,674,495, 3,785,825, British Patents 1,227,602, 1,251,345, 1,267, No. 005, No. 1,329,888, No. 1,330,932, German Patent No. 854,890, and the like.

The 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, and particularly preferably 10 to 30% by mass with respect to the total solid content of each recording layer. 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 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass.
The additive and binder of the present invention are preferably contained in the same layer.

  Further, for the purpose of enhancing the discrimination of the image and the resistance against scratches on the surface, a perfluoroalkyl group having 3 to 20 carbon atoms in the molecule as described in JP-A-2000-87318. A polymer having a (meth) acrylate monomer having 2 or 3 as a polymerization component can be used in combination.

  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 described in Japanese Laid-Open Patent Application No. 60-88942 and Japanese Patent Laid-Open No. 2-96755. p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, Phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-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 cyclic acid anhydride, phenols and organic acids in the printing plate material is 0.05 to 20 mass. % Is preferable, more preferably 0.1 to 5% by mass, and particularly preferably 0.1 to 10% by mass.

  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 to 10% by mass with respect to the total solid content of the recording layer.

  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 Copolymers containing fluorine monomers 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 Corporation. 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 to 15% by mass, more preferably 0.1 to 5% by mass.

  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.

  Furthermore, a plasticizer is added to the recording layer coating liquid in the present invention as needed to impart flexibility of the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid These oligomers and polymers are used.

  The lithographic printing plate precursor according to the invention can be usually produced by sequentially applying a recording layer coating solution prepared by dissolving the above components in a solvent onto a suitable support.

  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 to 50% by mass.

  In principle, the lower recording layer and the upper recording layer 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.

  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 or 1-methoxy-2-propanol that dissolves the alkali-soluble resin that is the upper recording layer component is selected, and the component contained in the lower recording layer is selected. The lower recording layer is applied and dried using a solvent system that dissolves, and then the upper recording layer mainly composed of an alkali-soluble resin is dissolved in methyl ethyl ketone or 1-methoxy-2-propanol, and then applied and dried. Stratification becomes possible.

  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 alkali-soluble resin in the lower recording layer is 80% by mass or less of the upper recording layer coating solvent. Is preferable from the viewpoint of chemical resistance, and if considering the viewpoint of scratch resistance, it is preferably in the range of 10 to 60% by mass.

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, from the viewpoint of residual film suppressing generation during development and printing durability ensuring, of 0.5g / m ² ~1.5g / m ² range preferably in the, more preferably in the range of ^{0.7g / m 2 ~1.0g / 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 . In addition, when there are two or more upper recording layers, the total amount is shown.

  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 to 1% by mass of the total solid content of the coating solution, and more preferably 0.05 to 0.5% by mass.

  The support used in the present invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), metal Plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, Polyvinyl acetal, etc.), paper laminated with metal as described above, or vapor-deposited paper, or plastic film.

  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 an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

  Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in 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 cannot be specified. However, in general, the concentration of the electrolyte is 1 to 80% by mass, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm. ^{2. A} voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable. When the amount of the anodized film is less than 1.0 g / m ² , the printing durability is insufficient, or the non-image part of the lithographic printing plate is easily scratched, and the ink adheres to the scratched part during printing. So-called “scratch stains” easily occur.

After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary.
The hydrophilization treatment used in the present invention is disclosed in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There are alkali metal silicate (such as aqueous sodium silicate) methods. In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, it is disclosed in potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and U.S. Pat. Nos. 3,276,868, 4,153,461, and 4,689,272. A method of treating with polyvinylphosphonic acid 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 which may have a substituent Organic phosphoric acid such as phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid and glycerophosphinic acid, amino acids such as glycine and β-alanine, and triethanolamine Hydroxy 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 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 to 20% by mass, preferably 0.05 to 5% by mass, the immersion temperature is 20 to 90 ° C., preferably 25 to 50 ° C., and 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, exposure is preferably performed with a light source having a light emission wavelength from the near infrared region to the infrared region, and specifically, image exposure is performed with a solid-state laser and a semiconductor laser emitting infrared light having a wavelength of 760 nm to 1200 nm. 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, the conditions are preferably 5 to 5 minutes within a range of 60 to 150 ° C. 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.

Conventionally known alkaline aqueous solutions 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, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples thereof include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium and lithium. In addition, 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. Trehalose-type oligosaccharides in which reducing groups are bonded to each other, and a configuration in which a reducing group of saccharides and a non-saccharide are bonded. 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 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 from 0.1 to 30% by mass, and more preferably from 1 to 20% by mass.
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. In addition, 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. Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. If necessary, the developer and replenisher may contain reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids such as sodium salts and potassium salts, and organic carboxylic acids, antifoaming agents, and hard water softeners. It can also be added. The printing plate developed using the developer and the replenisher is post-treated with 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.

  A method for processing a lithographic printing plate precursor according to the present invention will be described. If the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming has unnecessary image areas (for example, film edge marks of the original film) Necessary image portions are erased. Such erasing is preferably performed, for example, by applying an erasing solution as described in 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 that has been burned can be subjected to conventional treatments such as washing and gumming as needed, but a surface-conditioning solution containing a water-soluble polymer compound is used. In such a case, a so-called desensitizing treatment such as gumming can be omitted.
The planographic printing plate obtained by such processing is applied to an offset printing machine or the like and used for printing a large number of sheets.

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

[Acquisition of exemplified monomers used for specific polymers]
Exemplary monomer (1), exemplary monomer (2), exemplary monomer (8), exemplary monomer (9) and exemplary monomer (13) constituting the specific polymer of the present invention are described in Hofmann et al., Markromoleculare Cheme, Vol. 177. 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. A solution of 1.42 g (35.6 mmol) of sodium hydroxide in 30 ml of water was added and the reaction mixture was cooled to -10 ° C. The reaction was continued in the vessel at room temperature for 1 hour. , 10 mg of BHT 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. A solution of 8.10 g (89.5 mmol) of potassium hydroxide in 75 ml of water was added 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. BHT (25 mg) 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-pyrimidylbenzenesulfonamide 288.75 g (1.21 mol) 4-acetoamino-benzosulfonyl chloride and 113.8 g (1.21 mol) 2-aminopyrididine Were 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 liquefied 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 polymer (1)>
In a 250 ml reaction, exemplary monomer (1) having 160 mmol of sulfonamido group, 20.6 g (132 mmol) of benzylacetamide, 2.31 g (32 mmol) of acrylic acid and 104 g of γ-butyrolactone were added, 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. Trigonox DC50 (manufactured by AKZO NOBEL) 0.37 ml and trigonox 141 (manufactured by AKZO NOBEL) 1.48 ml dissolved in 3.66 ml of butyrolactone were 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. 16.8 ml of 1-methyl-2-propanol was added and the temperature was lowered to room temperature.
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 weight of the specific polymer (1) was Mn: 20500, Mw: 66000, PD: 3.05.

<Synthesis of specific polymers (2), (4), (5) and (6)>
In the following synthesis method, the specific polymer (2) is the exemplary monomer (1), the specific polymer (4) is the exemplary monomer (3), the specific polymer (5) is the exemplary monomer (7), and the specific polymer (6) is Exemplary monomer (5) is used as a raw material.
In a 250 ml reaction, 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 the mixture was stirred while stirring at 200 rpm. 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. Trigonox DC50 (manufactured by AKZO NOBEL) 0.35 ml and Trigonox 141 (manufactured by AKZO NOBEL) 1.39 ml dissolved in butyrolactone 3.43 ml were 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. 15.7 ml of 1-methyl-2-propanol was added and the temperature was lowered to room temperature.
The structure of the polymer was confirmed to be the same as that of the specific polymer (1). The results are shown below.
Specific polymer (2) Mn: 28000, Mw: 66000, PD: 2.84
Specific polymer (4) Mn: 34000, Mw: 162000, PD: 4.76
Specific polymer (5) Mn: 22000, Mw: 44000, PD: 1.91
Specific polymer (6) Mn: 23500, Mw: 55000, PD: 2.24

<Synthesis of specific polymers (3) and (7)>
In the following synthesis method, the specific polymer (3) uses the exemplified monomer (1) and the specific polymer (7) uses the exemplified monomer (8) as raw materials.
In a 250 ml reaction, 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 the mixture was stirred while stirring at 200 rpm. 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. Trigonox DC50 (manufactured by AKZO NOBEL) 0.37 ml and trigonox 141 (manufactured by AKZO NOBEL) 1.87 ml dissolved in butyrolactone 3.43 ml were 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. 16.8 ml of 1-methyl-2-propanol was added and the temperature was lowered to room temperature.
The structure of the polymer was confirmed to be the same as that of the specific polymer (1). The results are shown below.
Specific polymer (3) Mn: 30000, Mw: 85000, PD: 2.78
Specific polymer (7) Mn: 17000, Mw: 29000, PD: 1.67

[Examples 1-9, Comparative Examples 1-3]
<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. Created. 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) Desmut treatment temperature 30 ° C. A nitric acid concentration 1% by mass aqueous solution (containing 0.5% by mass of aluminum ions) was subjected to a desmut treatment by spraying, 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 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 After applying the following coating solution for the lower recording layer to the obtained support so that the coating amount becomes 0.85 g / m ² , using TABAI's PERFECT OVEN PH200 Wind Control was set to 7 and dried at 140 ° C. for 50 seconds. After that, the upper recording layer coating solution was applied to a coating amount of 0.15 g / m ^2, and then dried at 120 ° C. for 1 minute. The planographic printing plate precursors of Examples 1 to 9 and Comparative Examples 1 to 3 were obtained.

[Coating liquid for lower recording layer]
・ Polymer (1 type or 2 types of polymers shown in Table 1) 2.15 g
(The polymer content in Table 1 represents a mass ratio where the total amount of the polymer is 100.)
・ 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 (Dainippon Ink Chemical Co., Ltd.) 0.035g
・ Methyl ethyl ketone 24g
・ 13g 2-methoxy-1-propanol
・ 14g of γ-butyrolactone

The details of each polymer listed in Table 1 are as follows.
Specific polymers (1) to (7): Specific polymer synthesized as described above Novolak A: 2,5-xylenol / m / p cresol novolak
(5/55/40, weight average molecular weight 6500)
Novolac B: m / p cresol novolac
(60/40, weight average molecular weight 3500)
Novolac C: phenol / m / p cresol novolac
(20/50/30, weight average molecular weight 5000)
Novolak D: Phenol novolak (weight average molecular weight 4500; a polymer having a faster dissolution rate in an alkaline aqueous solution than a specific polymer)

[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 Dainippon Ink & Chemicals, Inc.]
・ Image formation improved fluorosurfactant 0.120g
[Megafuck F780 (30%), manufactured by Dainippon Ink & Chemicals, Inc.]
・ Methyl ethyl ketone 15.1g
-1-methoxy-2-propanol 7.7g

(Confirmation of dispersed phase)
Each lithographic printing plate precursor obtained in Examples 1 to 9 and Comparative Examples 1 to 3 was cut with a microtome or the like to give conductivity to the recording layer cross section, and then photographed with a scanning electron microscope (SEM). When photographed and observed, it was confirmed that a dispersed phase was present in each of the lower recording layers of Examples 1 to 9 and Comparative Example 3. The size of the dispersed phase was in the range of 0.05 μm to 0.55 μm. On the other hand, the lower recording layers of Comparative Examples 1 and 2 were in a uniform phase, and no dispersed phase was observed.

[Evaluation of lithographic printing plate precursor]
The lithographic printing plate precursors obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were evaluated for small dot reproducibility, printing durability, and chemical resistance as follows.

1. Evaluation of small dot reproducibility Each lithographic printing plate precursor obtained in Examples 1 to 9 and Comparative Examples 1 to 3 was tested at 4000 dpi, drum rotation speed 600 rpm, and output 90% on PTR-8800 manufactured by Dainippon Screen. The pattern was drawn in the form of an image.
The drawing was done by forming the letters “Fujifilm” in the Mincho style and changing the text size.
Development was carried out using a Fujifilm PS processor 940HII charged with Fujifilm's developer DT-2 (diluted to 43 mS / cm with water). The development time was 12 seconds.
The minimum number of points to reproduce without blurring was evaluated. In the table, “2” indicates that a two-point type character is reproduced without fading.
The results are shown in Table 2 below.

2. Evaluation of printing durability About each lithographic printing plate precursor obtained in Examples 1 to 9 and Comparative Example 1, In the same manner as above, drawing (exposure) and development were carried out to obtain a lithographic printing plate. Using the obtained planographic printing plates, printing was performed on high-quality paper using a KOR-D machine manufactured by Heidelberg. Evaluation of printing durability was performed based on the number of sheets until the recording layer of the lithographic printing plate was thinned and ink was not partially removed, so-called plate skipping occurred. The results are shown in Table 2 below.

3. 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 Table 2 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 obtained lithographic printing plate precursor, droplets of the test solutions 1 to 3 were dropped at different locations, 40 μL each. 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

  As is clear from Table 2, the lithographic printing plate precursors of Examples 1 to 9 have a dissolution rate in an alkaline aqueous solution of Comparative Examples 1 and 2 in which the lower layer does not form the dispersed phase and the resin that forms the dispersed phase in the lower layer. In comparison with the lithographic printing plate precursor of Comparative Example 3 that is faster than the dissolution rate of the resin that forms the matrix phase, it is excellent in all of high-definition image reproducibility, printing durability, and chemical resistance. I understand.

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 planographic printing plate precursor of the 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.

Explanation of symbols

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 (1)

The support has at least two positive recording layers containing a resin and an infrared absorber and increased in solubility in an alkaline aqueous solution by infrared laser exposure, and is supported among the two or more positive recording layers. The positive recording layer closest to the body includes two types including a polymer having a structural unit represented by the following general formula (I) and one or more selected from a structural unit represented by the following general formula (II) It is a layer containing the above resin, and at least one of the two or more resins forms a dispersed phase in the layer, and the dissolution rate of the resin forming the dispersed phase in the alkaline aqueous solution is the matrix phase. A lithographic printing plate precursor characterized by being slower than the dissolution rate of the resin to be formed in an alkaline aqueous solution.

In the general formula (I) and general formula (II), R ¹ represents a hydrogen atom or an alkyl group. Z represents —O— or —NR 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;

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