JP2006003658A - Planographic printing original plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive planographic printing original plate for an IR laser for direct platemaking with excellent scratch resistance and discrimination of a formed image and preferable plate wear. <P>SOLUTION: The planographic printing original plate has at least two layers of positive recording layers on a supporting body, the recording layers which contain a resin and an IR absorbent and the solubility of which with an alkali aqueous solution increases by IR laser exposure. The positive recording layer nearest to the supporting body of the positive recording layers contains at least two kinds of resins, wherein at least one kind of the resins forms a dispersion phase and at least one kind of the resins comprises a polymer containing maleimide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 easily be obtained with high output and small size. These lasers are very useful as an exposure light source for making a plate directly 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 The interaction weakens and dissolves in an alkaline developer to form a lithographic printing plate.
However, in such a positive lithographic printing plate material for infrared laser, the solubility between the non-exposed area (image area) with respect to the developer and the solubility of the exposed area (non-image area) under various use 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 if the surface condition slightly changes due to touching the surface during handling, the unexposed area (image area) dissolves and becomes a scratch mark during development, causing deterioration in printing durability and poor inking properties. There was a problem.

Such a problem originates from the essential difference in the plate making mechanism between the positive lithographic printing plate material for infrared laser and the positive lithographic printing plate material made by UV exposure. That is, in a positive type lithographic printing plate material 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 a non-exposed 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, IR dyes and the like in positive lithographic printing plate materials for infrared lasers only act as dissolution inhibitors for non-exposed areas (image areas), and do not promote dissolution of exposed areas (non-image areas). . Therefore, in the positive lithographic printing plate material for infrared laser, in order to make a difference in solubility between the non-exposed portion and the exposed portion, a binder resin having a high solubility in an alkaline 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 was a problem of affecting printing durability.

Various proposals have been made to solve the above problems. For example, there has been proposed a method in which the infrared absorber in the film is unevenly distributed in order to improve image discrimination (see, for example, Patent Document 1). However, the problem of scratch resistance on the surface of the recording layer has not been solved. Further, a lithographic printing plate precursor provided with a recording layer comprising a lower layer containing a sulfonamide acrylic resin and an upper layer containing a water-insoluble and alkali-soluble resin and a photothermal conversion agent and having increased solubility in an alkaline aqueous solution upon exposure. It has been proposed (see, for example, Patent Document 2). In this lithographic printing plate precursor, when the recording layer is removed in the exposed region, the lower layer excellent in alkali solubility is exposed, and the effect that an undesired residual film and the like are quickly removed by the alkali developer, The lower layer functions as a heat insulating layer, and the effect of effectively suppressing thermal diffusion to the support is exhibited. Furthermore, a method of imparting chemical resistance by blending a polymer in the lower layer has also been proposed (see, for example, Patent Document 3).
However, in order to form a recording layer having the multi-layer structure as described above, it is necessary to select resins having different characteristics as the resins used for each layer constituting the recording layer, and these interactive properties are required. Due to the problem of lowering, or due to good developability of the lower layer, undesired dissolution occurs at both ends of the lower layer portion in the image portion during development, affecting printing durability and image reproducibility. There was still room for improvement in order to fully utilize the advantages of the multi-layer structure.
JP 2001-281856 A JP 11-218914 A International Publication No. 01/46318 Pamphlet

  An object of the present invention is to provide a positive lithographic printing plate precursor for infrared laser for direct plate making which is excellent in scratch resistance and formed image discrimination and has good printing durability.

As a result of extensive research, the present inventor has provided a positive recording layer having a multilayer structure on a support, and formed a dispersed phase with the resin contained in the recording layer in the recording layer closest to the support. In addition, the inventors have found that the above problems can be solved by using a polymer containing maleimide as a resin used as a dispersed phase or a matrix phase (dispersion medium), and the present invention has been completed.
That is, the lithographic printing plate precursor of the present invention is a lithographic printing plate comprising 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. A positive recording layer closest to the support among the positive recording layers containing at least two kinds of resins, and at least one of those resins forms a dispersed phase; And at least one of the resins is a polymer containing maleimide.

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, if desired, in addition to the plurality of positive recording layers. It can be provided as long as the effect of is not impaired.

In addition, the dispersed phase by the resin in the recording layer is (1) a combination of a plurality of mutually incompatible resins, or (2) a granular polymer selected from microcapsules and latex is dispersed in a matrix resin. It can form by the method of making it.
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.

  As the lower recording layer, among the resins contained in the recording layer, the one that forms the matrix phase (dispersion medium) is made of a polymer compound that is water-insoluble and soluble in an alkaline aqueous solution, and forms a dispersed phase. An embodiment in which the compound containing an acid or radical-generating compound upon irradiation with an infrared laser is used, or among the resins contained in the recording layer, those that form a matrix phase are water-insoluble and alkaline aqueous solutions are acceptable. An embodiment in which the compound that is formed of a soluble polymer compound and forms a dispersed phase contains a compound whose alkali solubility is changed by irradiation with an infrared laser is preferable.

In the present invention, it is necessary that at least one of the resins contained in the lower recording layer is a polymer containing maleimide. The polymer containing maleimide is preferably used as a resin for forming a matrix phase (dispersion medium).
The polymer containing maleimide in the present invention includes a water-insoluble and alkali-soluble resin (hereinafter referred to as “specific maleimide / nitrile” as appropriate) obtained by copolymerizing an alkali-insoluble maleimide, a monomer having a nitrile group, and an alkali-soluble monomer. (Referred to as “resin”).

  As the size of the dispersed phase, it is preferable that the maximum major axis is 0.1 to 0.8 μm and the average major axis is 0.05 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 exposed resin portion, the dispersion phase having increased solubility in an alkaline aqueous solution by heat or light is formed in the lower resin matrix phase. Since the permeable path of the alkaline aqueous solution is formed inside, the dissolution of the alkali-soluble resin matrix phase under the exposed area is promoted. In the unexposed area (image area), the dispersed phase itself is alkaline. Since the solubility in the developing solution is low, the alkaline aqueous solution permeability into the lower resin matrix phase, particularly the penetration from the side can be effectively suppressed, and the damage in the alkaline aqueous solution in the image area can be suppressed, and Since the image area has excellent adhesion to the support, it can form sharp images with excellent image discrimination. Can, printing durability of the image portion is improved.

  Furthermore, when a specific maleimide / nitrile resin is applied as a polymer containing maleimide contained as an essential component in the lower layer, the specific maleimide / nitrile resin has an alkali-insoluble maleimide as a copolymerization component, so that the recording layer is Exhibits excellent dissolution resistance to organic solvents, making it less susceptible to damage from plate cleaners. In addition, since the specific maleimide / nitrile resin uses a monomer having a nitrile group as a copolymerization component, high film strength and high lipophilicity are expressed, which contributes to improvement in printing durability. On the other hand, the alkali-soluble monomer, which is another copolymer component, has an alkali-soluble group in the molecule. Therefore, by using such a monomer as the copolymer component, the development inhibitory effect was canceled by exposure. In the region (non-image portion region), it is considered that the resin material itself exhibits excellent solubility and a high-quality image without a residual film is formed. Further, by applying this specific maleimide / nitrile resin to the lower layer of the multi-layered recording layer as a polymer containing maleimide in the present invention, in the image area, that is, in the region where the upper layer of the recording layer exists as an alkali-resistant development layer. The high film strength and chemical resistance of the specific maleimide / nitrile resin described above function effectively. Further, in the non-image area, it is considered that when the upper layer is removed, it dissolves and disperses quickly in the alkali developer due to the original alkali solubility. For this reason, even if it uses resin with high alkali solubility for a lower layer component by raising the alkali resistance of an upper layer, the melt | dissolution which is not desired can be suppressed.

  In the present invention, a mode in which a polymer containing maleimide is used as the resin matrix phase in the lower layer and a dispersed phase in which solubility in an aqueous alkali solution is increased by heat or light is a particularly preferable mode, and scratch resistance and formation are formed. It is possible to obtain a lithographic printing plate precursor that is excellent in discriminating the printed image and has good printing durability, and the effect becomes more remarkable when compared with a single-layer type recording layer.

  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 according to the present invention is particularly useful for high-definition images such as FM screens that have been used with the recent CTP conversion, and commercially available FM screens such as Staccato (trade name: Creo). ), FAIRDOT, Randot (trade name: manufactured by Dainippon Screen), Co-Re screen (trade name: manufactured by Fuji Photo Film), and the like.

  According to the present invention, it is possible to provide a positive lithographic printing plate precursor for infrared laser for direct plate making which is excellent in scratch resistance and formed image discrimination and has good printing durability. For this reason, according to the present invention, it is possible to improve the plate-making stability particularly in a high-definition image, and further improve the printing durability of the high-definition image region. 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 present invention will be described in detail.
The lithographic printing plate precursor of the present invention is a lithographic printing plate precursor comprising 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. The positive recording layer closest to the support among the positive recording layers contains at least two types of resins, at least one of those resins forms a dispersed phase, and At least one of the resins is a polymer containing maleimide.
That is, the feature of the present invention is that a polymer containing maleimide is used as at least one kind of resin forming a dispersed phase in the lower layer and constituting the lower layer.

  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 for forming the dispersed phase, first, the dispersed phase obtained by the method (1) will be described. In the two or more kinds of 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 polymer containing maleimide.
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 treats 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 polymer compounds used in combination of two or more kinds of incompatible polymer compounds include urethane polymer compounds, acrylic polymer compounds, styrene polymer compounds, novolac resins, diazo resins, and amide polymers. Examples thereof include a compound and a polyether compound.
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. Further, those containing a urethane polymer compound are preferred from the viewpoint of being hardly damaged during development. In the present invention, at least one of such polymer compounds is a polymer containing maleimide.

  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 polymer binder, 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 photosensitive layer is processed, for example, by solvent etching according to the method described in “Polymer Alloy and Polymer Blend” (LA 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, Further, 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 the maximum major axis is usually 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, it is necessary that at least one of the resins constituting the lower layer is a polymer containing maleimide. As described above, the polymer containing maleimide in the present invention is preferably contained as a resin constituting the resin matrix phase in the lower layer.
Here, the “polymer containing maleimide” in the present invention means a polymer containing a maleimide skeleton in the polymer.
The polymer containing maleimide in the present invention is a water-insoluble and alkali-soluble resin (specific maleimide / nitrile resin) obtained by copolymerizing an alkali-insoluble maleimide, a monomer having a nitrile group, and an alkali-soluble monomer. This is a particularly preferred embodiment.

The specific maleimide / nitrile resin, which is the most preferred embodiment of the polymer containing maleimide in the present invention, will be described in detail below.
The alkali-insoluble maleimide used as the copolymer component of the specific maleimide / nitrile resin is not particularly limited as long as it is a compound that is insoluble in an aqueous alkali solution and has a maleimide skeleton in the molecule. Examples of the alkali-insoluble maleimide used in the present invention include those having a substituent on a nitrogen atom such as a structure represented by the following general formula (i).

In general formula (i), R represents an alkyl group, an aryl group, or an aralkyl group.
Here, when R represents an alkyl group, those having about 1 to 20 carbon atoms are preferred, and specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tertiary butyl. Group, cyclohexyl group and the like.
When R represents an aryl group, those having about 6 to 20 carbon atoms are preferable and may form a monocyclic or condensed polycyclic structure, and specifically include a phenyl group, a naphthyl group, and the like. .
A benzyl group is mentioned when R represents an aralkyl group.
R is particularly preferably a methyl group, a phenyl group, a naphthyl group, or a benzyl group.

  Specific examples of the alkali-insoluble maleimide include N-methylmaleimide, N-phenylmaleimide, N-naphthylmaleimide, N-benzylmaleimide and the like, but the present invention is not limited thereto.

  In the specific maleimide / nitrile resin, the copolymerization ratio of alkali-insoluble maleimide is preferably 10 to 60 mol%, more preferably 20 to 50 mol%. Moreover, you may use together 2 or more types of such alkali-insoluble maleimide as needed.

  The monomer having a nitrile group is not particularly limited as long as it has a nitrile group in the molecule and a functional group copolymerizable with other copolymerization components. As the copolymerizable functional group mentioned here, an unsaturated double bond capable of radical polymerization such as acryloyl group, methacryloyl group, vinyl group and styryl group is preferably used.

  As the monomer having a nitrile group, those represented by the following general formula (ii) are preferable.

In general formula (ii), A represents a hydrogen atom or a methyl group.
X represents a single bond or — (Y) _n —Z—, wherein Y represents an amide group or an ester group, and n represents 0 or 1. Z represents an alkylene group, an arylene group, or an aralkylene group. The alkylene group preferably has about 2 to 6 carbon atoms, the arylene group is preferably a phenylene group or a naphthylene group, and the aralkylene group is preferably a benzyl linking group.

Specific examples of the monomer having a nitrile group include acrylonitrile, methacrylonitrile, 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, 2-cyanoethyl acrylamide, 2-cyanoethyl methacrylamide, p-cyanophenyl methacrylamide, p-cyanophenyl methacrylate. P-cyanophenyl acrylamide, p-cyanophenyl acrylate, o-cyanophenyl methacrylamide, o-cyanophenyl methacrylate, o-cyanophenyl acrylamide, o-cyanophenyl acrylate, p- (2-cyanoethyloxy) phenyl methacrylamide, p- (2-cyanoethyloxy) phenyl methacrylate, o- (2-cyanoethyloxy) phenyl methacrylamide, o- (2-cyanoethyl) Ruoxy) phenyl methacrylate, p- (2-cyanoethyloxy) phenyl acrylamide, p- (2-cyanoethyloxy) phenyl acrylate, o- (2-cyanoethyloxy) phenyl acrylamide, o- (2-cyanoethyloxy) phenyl acrylate, etc. The present invention is not limited to these examples.
Among these, those having acrylonitrile, acrylamide skeleton, and methacrylamide skeleton are preferable because they have good chemical resistance. Further, among them, those having a phenylacrylamide skeleton and a phenylmethacrylamide skeleton are particularly preferable.

  The copolymerization ratio of the monomer having a nitrile group in the specific maleimide / nitrile resin is preferably 10 to 60 mol%, more preferably 20 to 50 mol%. If necessary, two or more monomers having such a nitrile group may be used in combination.

The alkali-soluble monomer is used for imparting an alkali-soluble function to the resin. Such an alkali-soluble monomer has a functional group that expresses alkali-solubility in its molecule (hereinafter referred to as “alkali-soluble group” as appropriate) and can be copolymerized with other copolymerization components. As long as it has, there is no particular limitation.
The alkali-soluble group is not particularly limited. Among them, (1) phenolic hydroxyl group, (2) sulfonamide group, (3) active imide group, (4) carboxyl group, (5) sulfonic acid group, (6) A phosphate group is particularly preferred.
Hereinafter, although the specific example of the monomer which has these alkali-soluble groups is given, this invention is not limited to these.

  (1) Examples of the monomer having a phenolic hydroxyl group include acrylamide, methacrylamide, acrylate ester, methacrylate 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-hydroxy Phenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2- (2-hydroxyphenyl) ethyl acrylate, 2- (3-hydroxyphenyl) Preferable are til acrylate, 2- (4-hydroxyphenyl) ethyl acrylate, 2- (2-hydroxyphenyl) ethyl methacrylate, 2- (3-hydroxyphenyl) ethyl methacrylate, 2- (4-hydroxyphenyl) ethyl methacrylate, etc. Can be used.

(2) The polymerizable monomer having a sulfonamide group includes a sulfonamide group —NH—SO ₂ — in which at least one hydrogen atom is bonded on a nitrogen atom, and a polymerizable unsaturated bond in one molecule. The polymerizable monomer which consists of a low molecular compound which has 1 or more is mentioned. Among these, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group is preferable.

(3) Examples of the monomer having an active imide group include low molecular compounds each having one or more active imide groups and polymerizable unsaturated bonds in one molecule. As such a compound, specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide, maleimide and the like can be preferably used.

(4) Examples of the monomer having a carboxyl group include unsaturated carboxylic acids each having one or more carboxyl groups and unsaturated double bond groups in the molecule, such as acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid. It is done.

(5) As a monomer having a sulfonic acid group or a salt thereof, AMPS (2-acrylamido-2-methyl-1-propanesulfonic acid) can be used.

(6) Examples of the monomer containing a phosphate ester include mono (2-methacryloyloxyethyl) acid phosphate and mono (2-acryloyloxyethyl) acid phosphate.

  The copolymerization ratio of the alkali-soluble monomer in the specific maleimide / nitrile resin is preferably 5 to 50 mol%, and more preferably 10 to 40 mol%.

The specific maleimide / nitrile resin may further be copolymerized with the following monomers (m1) to (m9) as a fourth component.
(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 such as N-phenylacrylamide or methacrylamide, N-vinylpyrrolidone.

(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.

  The specific maleimide / nitrile resin preferably has a weight average molecular weight (Mw) of 2,000 or more and a number average molecular weight of 500 or more. More preferably, the weight average molecular weight is 5,000 to 300,000, the number average molecular weight is 800 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10. These specific maleimide / nitrile resins may be used alone or in combination of two or more.

  The content of the polymer containing maleimide in the lower layer is preferably 3% by mass or more, more preferably 10% by mass or more, and more preferably 25% by mass or more with respect to the total solid content of the lower recording layer. Is more preferable.

  The components of the lithographic printing plate precursor according to the invention will be described in more detail. First, the poly type 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 a polymer containing maleimide such as the above-mentioned specific maleimide / nitrile resin.
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 It is preferably 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. For example, although the following are illustrated, it is not limited to these.

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

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

(2) Examples of the alkali-soluble polymer compound having a sulfonamide group include a polymer compound obtained by homopolymerizing a polymerizable monomer having a sulfonamide group or copolymerizing the monomer with another polymerizable monomer. . 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 these, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group is preferable.

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

  Furthermore, as 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, conventionally known graft copolymerization method, block copolymerization method, random copolymerization method and 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 conditions for drying the undried coating film after coating with the photosensitive solution are also important in order to make the size of the dispersed phase of the sea-island structure in the lower recording layer predetermined. It is known to be a factor. 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, diazo resins, and polyethers.
(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) In one molecule, a low molecular compound having at least one sulfonamide group having at least one hydrogen atom bonded to a nitrogen atom and one or more polymerizable unsaturated bonds, for example, the following formulas (I) to (V) ).

In the 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, cycloalkylene group, arylene group or aralkylene group. R ³ , R ⁷ and R ^{13 each} represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may have a substituent, a cycloalkyl group, an aryl group or 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-carboxyl styrene.

  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.

Examples of the water-insoluble and alkaline aqueous-soluble urethane polymer compound 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, and other alkali-soluble novolak resins 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 addition, as the diazo resin used in the present invention, a diazo resin, that is, a polymer or oligomer having a diazonio group in the side chain is preferably used. Particularly useful are diazo resins which are condensates of aromatic diazonium salts with, for example, active carbonyl-containing compounds (eg, formaldehyde). Preferred diazo resins include, for example, 4-diazo-diphenylamine, 1-diazo-4-N, N-dimethylaminobenzene, 1-diazo-4-N, N-diethylaminobenzene, 1-diazo-4-N-ethyl. -N-hydroxyethylaminobenzene, 1-diazo-4-N-methyl-N-hydroxyethylaminobenzene, 1-diazo-2,5-diethoxy-4-benzoylaminobenzene, 1-diazo-4-N-benzyl Aminobenzene, 1-diazo-4-morpholinobenzene, 1-diazo-2,5-dimethoxy-4-p-tolylmercaptobenzene, 1-diazo-2-ethoxy-4-N, N-dimethylaminobenzene, 1 -Diazo-2,5-dibutoxy-4-morpholinobenzene, 1-diazo-2,5-diethoxy-4-morpholine Benzene, 1-diazo-2,5-dimethoxy-4-morpholinobenzene, 1-diazo-2,5-diethoxy-4-p-tolylmercaptobenzene, 1-diazo-3-ethoxy-4-N-methyl- N-benzylaminobenzene, 1-diazo-3-chloro-4-N, N-diethylaminobenzene, 1-diazo-3-methyl-4-pyrrolidinobenzene, 1-diazo-2-chloro-4-N, N -Dimethylamino-5-methoxybenzene, 1-diazo-3-methoxy-4-pyrrolidinobenzene, 3-methoxy-4-diazodiphenylamine, 3-ethoxy-4-diazodiphenylamine, 3- (n-propoxy) -4 A diazo monomer such as diazodiphenylamine, 3-isopropoxy-4-diazodiphenylamine, formaldehyde, Condensing agents such as toaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, and benzaldehyde are each in a molar ratio of 1: 1 to 1: 0.5, preferably 1: 0.8 to 1: 0.6. The reaction product of the condensate obtained by condensation by a normal method and an anion is mentioned.

  Examples of the anion used for the reaction include tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, and 2,5-dimethylbenzenesulfonic acid. 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, di-t-butylnaphthalene Examples include sulfonic acid, 1-naphthol-5-sulfonic 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.

  Further, a reaction product of the above-mentioned diazo monomer, a condensate obtained from an aldehyde having a carboxylic acid and / or phenol or an acetal thereof (and the above-mentioned condensing agent if necessary) and the above-mentioned anion, The diazo resins described in JP-A-1-102456 and JP-A-1-102457 are also preferably used in the present invention. In particular, a diazo resin containing a carboxylic acid group is preferable because developability is improved and, as a result, stains are less likely to occur in a non-image area during printing.

  Among these diazo resins, from the viewpoint that both the decomposability by heat generated by light and the storage stability of the obtained lithographic printing plate precursor are good, the structural unit represented by the following general formula (1), or A diazo resin having a structural unit represented by the general formula (1) and the following general formula (2) and having a weight average molecular weight of 500 or more, preferably 800 or more, more preferably 1000 or more is most preferable. When the weight average molecular weight is less than 500, the film strength of the image portion is lowered. The ratio (mass ratio) of the structural units represented by the formulas (1) and (2) is preferably 100: 0 to 30:70. If the amount of the structural units represented by the formula (1) is small, the strength of the image area is increased. Lower. Moreover, the other structural unit may be included.

In the formula, R ¹ , R ² , R ³ , R ⁴ , and R ⁵ are each hydrogen, halogen (eg, fluorine, chlorine, bromine), —COOH, —OPO ₃ H ₂ , —PO ₃ H ₂ , —SO ₃ H, -OH, substituent (e.g. _{-COOH, -OPO 3 H 2, -PO} 3 H 2, -SO 3 H, -OH) carbon atoms which may have a 15 or less hydrocarbon groups (e.g. , Carboxymethyl group, hydroxyethyl group, p-carboxymethoxyphenyl group) / alkoxy group (for example, methoxy group, hexyloxy group, carboxymethoxy group) / aryloxy group (for example, phenoxy group, p-carboxymethoxyphenoxy group) , Y represents NR ⁶ , O or S, and R ⁶ represents hydrogen or a hydrocarbon group having 12 or less carbon atoms (for example, methyl group, ethyl group, hexyl group). X ⁻ represents PF ₆ ^— or benzenesulfonate / naphthalenesulfonate which may have a substituent having 20 or less carbon atoms. Examples of the substituent include a methyl group, a butyl group (including n-, i-, sec-, and t-butyl groups), a hexyl group, a decyl group, a dodecyl group, and a benzoyl group.

  In the case of a positive recording layer, the lower recording layer comprising a polymer matrix phase containing a dispersed phase formed in this way is a compound whose solubility in an alkaline solution is changed by an infrared absorber and heat in the dispersed phase. Is contained in 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 mentioned 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 acid upon irradiation with light having a wavelength of 200 to 500 nm or heating at 100 ° C. or higher. Examples include known acid generators used for decolorizers, photochromic agents, microresists, and the like, known compounds that generate acid upon thermal decomposition, and mixtures thereof. The acid generated is preferably a strong acid having a pKa of 2 or less, such as sulfonic acid and hydrochloric acid.
Examples of the initiator suitably used in the present invention include triazine compounds described in JP-A No. 11-95415, and latent Brönsted acids described in JP-A No. 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 included 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 included 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).

  Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and nickel thiolate complexes.

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

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

  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 size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. When the particle diameter of the pigment is less than 0.01 μm, it is not preferable from the viewpoint of stability of the dispersion in the image recording layer coating solution, and when it exceeds 10 μm, it is not preferable from the viewpoint of uniformity of the image recording layer.

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).
In the case of such a negative recording layer, the infrared absorber is preferably a dye, and particularly preferred dyes are onium salt structures described in paragraphs [0018] to [0034] of JP-A No. 11-291552. Infrared absorbers having

  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 used in the positive recording layer is preferably a dye, and has a onium salt structure described in paragraphs [0018] to [0034] of JP-A No. 11-291652 as a suitable example. An infrared absorber is mentioned.

  In the positive recording layer of the present invention, for the purpose of further improving sensitivity and development latitude, an infrared absorber exhibiting dissolution inhibiting ability such as the above-mentioned cyanine dyes, pyrylium salts and anionic dyes, and other dyes Or a pigment etc. can also be used together.

  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 additive can be used for the lower layer 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 include acrylic polymers containing fluorine of P-1 to P-13 described in JP-A No. 11-288093 and A-1 to JP-A No. 2000-187318. A fluorine-containing polymer obtained by copolymerizing an A33 fluorine-containing acrylic monomer with an arbitrary acrylic monomer can be used.
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 and 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. Note that even if it exceeds 5.0 mass%, the effect of improving the development latitude is not improved, and on the contrary, there is a concern that the surface of the image recording layer becomes slightly soluble due to the influence of the fluorine-containing polymer and the sensitivity is lowered.

  If necessary, the lower recording layer or other recording layer according to the present invention is thermally decomposable such as an onium salt, an o-quinonediazide compound, an aromatic sulfone compound, and an aromatic sulfonic acid ester compound, and does not decompose. Then, 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 used in the present invention include S.P. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Baletal, Polymer, 21, 423 (1980), diazonium salts described in JP-A-5-158230, US Pat. Nos. 4,069,055, 4,069,056, and JP-A-3-140140 Ammonium salts described in the C. Necker et al., Macromolecules, 17, 2468 (1984), C.I. S. Wenetal, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056; V. Crivello et al., Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, US Pat. Nos. 5,041,358, 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 the dissolution inhibitor 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 compounds described in pages 339 to 352 of “Light Sensitive Systems” by John Coser (John Wiley & Sons. Inc.) 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) -diazide sulfonic 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, phenyl Suphonic 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 each recording layer according to 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 of the present invention, a nonionic surfactant as described in JP-A-62-251740 or JP-A-3-208514 is used in order to broaden the processing stability against 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.) and the like. The siloxane compound is preferably a block copolymer of dimethylsiloxane and polyalkylene oxide. Specific examples include DBE-224, DBE-621, DBE-712, DBP-, manufactured by Chisso Corporation. Polyalkylene oxide-modified silicones such as 732, DBP-534, and Tego Glide 100 manufactured by Tego, Germany.
The proportion of the nonionic surfactant and the 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 applying 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.
The lower layer (lower recording layer) and the upper layer (other recording layers) are preferably formed by separating the two layers in principle.

As a method for forming the two layers separately, for example, a method using a difference in solvent solubility between a component contained in the lower layer and a component contained in the upper layer, or after applying the upper layer, a solvent is rapidly used. However, it is not limited to these methods.
As a method of utilizing the difference in solvent solubility between the component contained in the lower layer and the component contained in the upper layer, a method using a solvent that does not dissolve the alkali-soluble resin contained in the lower layer when applying the upper layer coating solution. Can be 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 layer component, a component insoluble in a solvent such as methyl ethyl ketone or 1-methoxy-2-propanol that dissolves the alkali-soluble resin that is the upper layer component is selected, and the lower layer is applied using a solvent system that dissolves the lower layer component. -Drying and then dissolving the upper layer mainly composed of an alkali-soluble resin with methyl ethyl ketone, 1-methoxy-2-propanol or the like, and applying and drying can be made into two layers.

  When applying a method that uses a solvent that does not dissolve the alkali-soluble resin contained in the lower layer when applying the upper layer coating solution, the upper layer coating solvent does not dissolve in the solvent that dissolves the alkali-soluble resin contained in the lower layer. You may mix and use a solvent. By changing the mixing ratio of the two solvents, interlayer mixing between the upper layer and the lower layer can be arbitrarily controlled. When the ratio of the solvent that dissolves the alkali-soluble resin in the lower layer increases, a part of the lower layer dissolves when the upper layer is applied, and after drying, it is contained as a particulate component in the upper layer. Protrusions are made and scratch resistance is improved. On the other hand, when the lower layer components are dissolved into the upper layer, the film quality of the lower 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 upper layer coating solvent, the solvent for dissolving the lower layer alkali-soluble resin should be 80% by mass or less of the upper layer coating solvent. From the viewpoint, it is preferably in the range of 10 to 60% by mass in consideration of scratch resistance.

Next, after applying the second layer (upper layer), as a method of drying the solvent very quickly, a method of blowing high-pressure air from a slit nozzle installed almost at right angles to the running direction of the web, heating of steam, etc. The method of giving thermal energy as conduction heat from the lower surface of a web from the roll (heating roll) supplied to the inside of the medium, or a 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 layer when the upper layer is applied, the upper layer application method is preferably a non-contact type. Further, although it is a contact type, it is possible to use bar coater coating as a method generally used for solvent-based coating, but it is desirable to apply by forward driving in order to prevent damage to the lower layer.

The coating amount after drying of the lower recording layer in the planographic printing plate precursor of the present invention is in the range of 0.5 to 1.5 g / m ² from the viewpoint of securing printing durability and suppressing the occurrence of residual film during development. Is more preferable, and the range of 0.7 to 1.0 g / m ² is more preferable.
The coating amount after drying of other recording layer (upper layer) is preferably in the range of 0.05 to 1.0 g / m ^2, more preferably in the range of 0.07~0.7g / m ² It is. In addition, when an upper layer is two or more layers, the total amount is shown.
In these recording layers, generally, as the coating amount decreases, the apparent sensitivity increases, but the development latitude and film characteristics tend to decrease. In particular, when the thickness of the recording layer is too thick, the recording layer is easily affected by thermal diffusion in the deep part, and there is a concern that the image formability in the vicinity of the support is lowered.

  In the coating solution for the lower 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 is used. 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 used in the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is 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 solution, 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 polyvinyl phosphonic 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 layers) on a support, and if necessary, a support and a lower layer. An undercoat layer can be provided therebetween.
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 above organic compound in an organic solvent or a mixed solvent thereof to adsorb the above 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 a basic substance such as ammonia, triethylamine or potassium hydroxide, or an acidic substance such as hydrochloric acid or phosphoric acid. A yellow dye can also be added to improve the tone reproducibility of the image recording material.
The coating amount of the organic undercoat layer is suitably ² to 200 mg / m ² , preferably 5 to 100 mg / m ² . If the coating amount is less than 2 mg / m ² , sufficient printing durability cannot be obtained. Moreover, even if it is larger than 200 mg / m ^2, it is the same.

The positive lithographic printing plate precursor produced as described above is usually subjected to image exposure and development processing.
Examples of the active light source used for image exposure include a mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, and a carbon arc lamp. Examples of radiation include electron beams, X-rays, ion beams, and far infrared rays. Also, g-line, i-line, deep-UV light, and high-density energy beam (laser beam) are used.
Examples of the laser beam include helium / neon laser, argon laser, krypton laser, helium / cadmium laser, and KrF excimer laser.
In the present invention, it is particularly preferable to perform exposure with a light source having a light emission wavelength from the near infrared region to the infrared region. It is preferable.

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

Conventionally known alkaline aqueous solutions can be used as the developer and replenisher used for 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 a developer including a replenisher). For example, sodium silicate, potassium, trisodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples 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, saccharide reducing groups and non-saccharides are bonded to each other 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, mustard oil glycosides, and the like. Examples of the sugar alcohol include D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit, D, L-talit, zulsiit and allozulcit. Further, maltitol obtained by hydrogenation of disaccharides and reduced form (reduced syrup) obtained by hydrogenation of oligosaccharides are preferably used. Among these, sugar alcohol and saccharose are particularly preferred non-reducing sugars, and D-sorbite, saccharose, and reduced starch 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 by applying an erasing solution as described in, for example, Japanese Patent Publication No. 2-13293 to an unnecessary image portion, leaving it for a predetermined time, and then washing with water. A method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber as described in JP-A-5-174842 can also be used.

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

In general, the amount of the surface-adjusting solution applied is suitably 0.03 to 0.8 g / m ² (dry mass). The planographic 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 are preferably in the range of 180 to 300 ° C. and in the range of 1 to 20 minutes, although depending on the type of components forming the image.
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 or the like is used. If so, so-called desensitizing treatment such as gumming can be omitted.
The lithographic 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.

[Synthesis of specific maleimide / nitrile resin]
The “specific maleimide / nitrile resin”, which is the “polymer containing maleimide” in the present invention, was synthesized as follows.
<Synthesis Examples 1-4>
Under a nitrogen stream, 26.25 g of N-phenylmaleimide, 7.95 g of acrylonitrile, 10.65 g of acrylamide, and 4.3 g of methacrylic acid were added to 133.1 g of 2-methoxyethanol, heated to 70 ° C., and then α, α′- 0.25 g of azobisisobutyronitrile was added and a polymerization reaction was carried out for 8 hours. Thus, a 2-methoxyethanol solution of the specific maleimide / nitrile resin (1), which is a copolymer of N-phenylmaleimide, acrylonitrile, acrylamide, and methacrylic acid used in the present invention, was obtained. The non-volatile content of this solution was 24.8%.
Next, a 2-methoxyethanol solution of the specific maleimide / nitrile resins (2) to (4) according to the present invention was obtained in the same manner as described above except that the starting material was changed. The nonvolatile content of each solution was 24.5% for resin (2), 24.0% for resin (3), and 24.7% for resin (4).
The copolymerization ratio of the polymer thus obtained was determined by C ¹³ -NMR and acid titration after re-precipitation-filtration of this solution in 1 L of water and removal of moisture by vacuum drying. The structural units, the respective copolymerization ratios (mol%), and the molecular weights of the resins (1) to (4) are shown in Table 1 below.

[Examples 1 to 4]
[Production of support]
<Aluminum plate>
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.025 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: It contains 0.03% by mass, and the balance is prepared using Al and an inevitable impurity aluminum alloy. After the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Produced. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, the temperature was kept constant 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. Furthermore, after performing heat processing using a continuous annealing machine at 500 degreeC, it finished by cold rolling to 0.24 mm in thickness, and obtained the aluminum plate of JIS1050 material. In addition, the minor axis of the average crystal grain size of the obtained aluminum was 50 μm, and the major axis was 300 μm. After making this aluminum plate into width 1030mm, it used for the surface treatment shown below.

<Surface treatment>
For the surface treatment, the following various treatments (a) to (k) were continuously performed. In addition, after each process and water washing, the liquid draining was performed with the nip roller.
(A) Mechanical surface roughening treatment Using an apparatus as shown in FIG. 1, a suspension of abrasive (pumice) having a specific gravity of 1.12 and water is supplied as a polishing slurry to the surface of the aluminum plate. However, a mechanical surface roughening treatment was performed with a rotating roller-like nylon brush. In FIG. 1, 1 is an aluminum plate, 2 and 4 are roller brushes, 3 is a polishing slurry, and 5, 6, 7 and 8 are support rollers. The average particle size of the abrasive was 30 μm, and the maximum particle size was 100 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 45 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkali etching treatment The aluminum plate obtained above was subjected to an etching treatment by spraying using an aqueous solution having a caustic soda concentration of 2.6% by mass, an aluminum ion concentration of 6.5% by mass and a temperature of 70 ° C. / M ² dissolved. Then, water washing by spraying was performed.

(C) Desmutting treatment Desmutting treatment was performed by spraying with a 1% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a step of performing an electrochemical surface roughening treatment using alternating current in a 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 50 ° C. The AC power supply waveform is the waveform shown in FIG. 2, the time TP until the current value reaches the peak from zero is 0.8 msec, the duty ratio is 1: 1, the 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 The aluminum plate was subjected to etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass to dissolve the aluminum plate by 0.50 g / m ² . Removes the smut component mainly composed of aluminum hydroxide that was generated when electrochemical roughening treatment was performed using the alternating current of the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

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

(G) Electrochemical roughening treatment An electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 5.0 g / L aqueous solution (containing 5 g / L of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform is the waveform shown in FIG. 2, and the time TP until the current value reaches the peak from zero is 0.8 msec, the duty ratio is 1: 1, and the trapezoidal square wave AC is used to connect the carbon electrode. Electrochemical roughening treatment was performed as a counter electrode. Ferrite was used for the auxiliary anode. The electrolytic cell used was the one shown in FIG.
The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ^{2 as} the total amount of electricity when the aluminum plate was the anode. Then, water washing by spraying was performed.

(H) Alkaline etching treatment An aluminum plate was subjected to an etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass%, and the aluminum plate was dissolved at 0.10 g / m ² . Removes the smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening treatment was performed using alternating current in the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

(I) Desmutting treatment A desmutting treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid at a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

(J) Anodizing treatment Using an anodizing apparatus having a structure shown in FIG. 4 (first and second electrolysis unit length 6 m each, first and second feeding unit length 3 m each, first and second feeding unit length 2.4 m each) Anodizing was performed. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 50 g / L (containing 0.5 mass% of aluminum ions) and a temperature of 20 ° C. Then, water washing by spraying was performed.
In the anodizing device, the current from the power supply 67a and the power supply 67b flows to the first power supply electrode 65a provided in the first power supply section 62a, flows to the aluminum plate 11 through the electrolytic solution, and the first electrolysis section 63a. Then, an anodized film is formed on the surface of the aluminum plate 11, passes through the electrolytic electrodes 66a and 66b provided in the first electrolysis part 63a, and returns to the electrodes 67a and 67b.
The amount of electricity fed from the power sources 67a and 67b to the first feeding unit 62a is equal to the amount of electricity fed from the power sources 67c and 67d to the second feeding unit 62b, and the first electrolysis unit 63a and the second electrolysis unit Both current densities at 63b were about 30 A / dm ² . In the 2nd electric power feeding part 62b, it electrically fed through the oxide film surface of 1.35 g / m < ² > produced | generated by the 1st electrolysis part 63a. The final oxide film amount was 2.7 g / m ² .

(K) Alkali metal silicate treatment An aluminum support obtained by anodizing treatment was immersed in a treatment tank of a 1% by mass aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C. for 10 seconds. Acid salt treatment (silicate treatment) was performed. Thereafter, washing with water using well water was performed to obtain a support subjected to a surface silicate hydrophilization treatment. On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds to form a coating film. The coating amount of the coating film after drying was 15 mg / m ² .

<Undercoat liquid composition>
・ The following compound 0.3g
・ Methanol 100g
・ Water 1g

[Formation of recording layer (multilayer)]
The lower layer coating solution 1 having the following composition was coated on the obtained web-shaped substrate with a bar coater so that the coating amount was 0.85 g / m 2, dried at 160 ° C. for 44 seconds, and immediately cooled with cold air at 17 to 20 ° C. It cooled until the temperature of a support body became 35 degreeC.
Thereafter, the upper layer coating solution 1 having the following composition was applied by a bar coater so that the coating amount was 0.22 g / m ² , dried at 148 ° C. for 25 seconds, and further slowly cooled with air at 20 to 26 ° C. The planographic printing plate precursor of Example 1 was prepared.

<Lower layer coating solution 1>
-Specific maleimide / nitrile resin (solid) obtained in the above synthesis example
(Of the kind described in Table 2 below) 1.92 g
・ Novolac resin 1 0.192g
(2,3-xylenol / m-cresol / p-cresol ratio = 10/20/70, weight average molecular weight 3300)
・ Cyanine dye A (the following structure) 0.134 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.032g
・ The ethyl violet counter ion is changed to 6-hydroxynaphthalenesulfonic acid 0.0781 g
・ Polymer 1 (the following structure) 0.035g
・ Methyl ethyl ketone 25.41g
・ 1-methoxy-2-propanol 12.97g
・ Γ-butyrolactone 13.18 g

<Upper layer coating solution 1>
・ M, p-cresol novolak 0.3479g
(M / p ratio = 6/4, weight average molecular weight 4500,
Contains 0.8% by mass of unreacted cresol)
-Polymer 3 (the following structure MEK 30% solution) 0.1403g
・ Cyanine dye A (the above structure) 0.0192 g
・ Polymer 1 (the above structure) 0.015 g
-Polymer 2 (the following structure) 0.00328g
・ Quaternary ammonium salt (the following structure) 0.0043g
・ Surfactant (polyoxyethylene sorbite fatty acid ester HLB8.5, GO-4 manufactured by Nikko Chemicals Co., Ltd.) 0.008 g
・ Methyl ethyl ketone 6.79g
・ 1-methoxy-2-propanol 13.07 g

Example 5
A lithographic printing plate precursor of Example 5 was produced in the same manner as in Example 1 except that the upper layer coating liquid 1 in Example 1 was changed to the upper layer coating liquid 3 having the following composition.

<Upper layer coating solution 3>
・ Novolac resin 2 0.3479g
(Phenol / m / p ratio = 5/3/2,
(Weight average molecular weight 5300, unreacted cresol containing 1.5% by mass)
・ Polymer 3 (said structure MEK 30% solution) 0.1403 g
・ Cyanine dye A (the above structure) 0.0192 g
・ Polymer 1 (the above structure) 0.015 g
・ Polymer 2 (the above structure) 0.00328 g
・ Sulphonium salt (the following structure) 0.08g
・ Surfactant (polyoxyethylene sorbite fatty acid ester HLB8.5, GO-4 manufactured by Nikko Chemicals Co., Ltd.) 0.008 g
・ Methyl ethyl ketone 6.79g
・ 1-methoxy-2-propanol 13.07 g

Example 6
A lithographic printing plate precursor of Example 6 was prepared in the same manner as in Example 5 except that the support in Example 5 was changed to a support prepared as follows.

An aluminum plate (material: JIS A 1050) having a thickness of 0.3 mm is etched for 10 seconds at a caustic soda concentration of 30 g / l, an aluminum ion concentration of 10 g / l, a liquid temperature of 60 ° C., washed with running water, and 10 g / l nitric acid. After neutralizing and washing with water. Using an alternating current of a sine wave under the condition of applied voltage Va = 20 V, an electric current of 500 C / dm ² in an aqueous solution having a hydrogen chloride concentration of 15 g / l, an aluminum ion concentration of 10 g / l, and a liquid temperature of 30 ° C. The surface was subjected to an electrochemical surface roughening treatment in an amount and washed with water, followed by an etching treatment for 10 seconds at a caustic soda concentration of 30 g / l, an aluminum ion concentration of 10 g / l and a liquid temperature of 40 ° C., and then washed with running water. Next, it was desmutted in a sulfuric acid aqueous solution having a sulfuric acid concentration of 15% by mass and a liquid temperature of 30 ° C., and washed with water. Furthermore, in a 10% by mass sulfuric acid aqueous solution at a liquid temperature of 20 ° C., an anodizing treatment was performed under a condition of a current density of 6 A / dm ² by direct current so that the amount of the anodized film would be 2.5 g / m ² , and washing with water. , Dried. Then, it processed for 10 second at 30 degreeC with 2.5 mass% sodium silicate aqueous solution, and produced the board | substrate. The centerline average roughness (Ra) of the substrate was measured using a needle having a diameter of 2 μm and found to be 0.48 μm. On the silicate-treated aluminum substrate obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds to form a coating film. The coating amount of the coating film after drying was 17 mg / m ² .

Example 7
In the production of the support of Example 1, the same undercoating and recording layer (lower layer / upper layer) as in Example 1 were provided except that the silicate treatment was not performed after the anodic oxidation treatment. A printing plate precursor was prepared.

[Comparative Example 1]
A lithographic printing plate precursor of Comparative Example 1 was prepared in the same manner as in Example 1 except that the lower layer coating solution 1 in Example 1 was changed to a lower layer coating solution 2 having the following composition not containing a specific maleimide / nitrile resin. .

<Lower layer coating solution 2>
N- (aminosulfonylphenyl) methacrylamide / methacrylic acid / acrylonitrile 1.92 g
(32/37/31: weight average molecular weight 45,000)
・ Novolac resin 1 0.192g
(2,3-xylenol / m-cresol / p-cresol ratio = 10/20/70, weight average molecular weight 3300)
・ Cyanine dye A (the above structure) 0.134 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.032g
・ The ethyl violet counter ion is changed to 6-hydroxynaphthalenesulfonic acid 0.0781 g
・ Polymer 1 (the above structure) 0.035 g
・ Methyl ethyl ketone 25.41g
・ 1-methoxy-2-propanol 12.97g
・ Γ-butyrolactone 13.18 g

[Comparative Example 2]
Comparative Example 2 in which a dispersed phase was not formed in the lower layer in the same manner as in Example 1 except that the lower layer coating solution 1 in Example 1 was changed to a lower layer coating solution 3 having the following composition containing no novolak resin. A lithographic printing plate precursor was prepared.

<Lower layer coating solution 3>
Specific maleimide / nitrile resin (1) obtained in the above synthesis example (solid)
2.133 g
・ Cyanine dye A (the following structure) 0.134 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.032g
・ The ethyl violet counter ion is changed to 6-hydroxynaphthalenesulfonic acid 0.0781 g
・ Polymer 1 (the following structure) 0.035g
・ Methyl ethyl ketone 25.41g
・ 1-methoxy-2-propanol 12.97g
・ Γ-butyrolactone 13.18 g

[Comparative Example 3]
On the support obtained in the same manner as in Example 1, a recording layer (single layer) coating solution 1 having the following composition was applied and dried to a coating amount of 1.2 g / m @ 2 to form a recording layer. A lithographic printing plate precursor of Comparative Example 3 was obtained.

<Recording layer (single layer) coating solution 1>
・ Novolak resin 0.5g
(M / p-cresol (6/4), weight average molecular weight 7,000,
Unreacted cresol 0.5% by mass)
・ N- (aminosulfonylphenyl) methacrylamide / methacrylic acid / acrylonitrile 1.0 g
(32/37/31: weight average molecular weight 45,000)
・ Cyanine dye A (the above structure) 0.1 g
・ Dodecyl stearate 0.06g
・ Phthalic anhydride 0.05g
・ 0.002 g of p-toluenesulfonic acid
・ Ethyl violet counter ion with 6-hydroxynaphthalenesulfonic acid 0.02g
・ Fluorine polymer 0.015g
(Megafuck F-176 (solid content 20%),
Dainippon Ink & Chemicals, Inc.)
・ Fluoropolymer 0.035g
(Megafuck MCF-312 (solid content 30%),
Dainippon Ink & Chemicals, Inc.)
・ Γ-Butyrolactone 8.5g
・ 3.5 g of 1-methoxy-2-propanol

[Evaluation of planographic printing plate precursor]
(Evaluation of printing durability)
-Exposure-
The lithographic printing plate precursors of Examples 1 to 7 and Comparative Examples 1 to 4 were drawn with test patterns in the form of images by changing the exposure energy with a Trend setter manufactured by Creo.
-Development processing-
Thereafter, the lithographic printing plate precursors of Examples 1 to 6 and Comparative Examples 1 to 4 were charged with developer DT-2 (diluted to a conductivity of 43 mS / cm) manufactured by Fuji Photo Film Co., Ltd. Development was performed using a PS processor LP940H manufactured by Fuji Photo Film Co., Ltd. at a development temperature of 30 ° C. and a development time of 12 seconds. The lithographic printing plate precursor of Example 7 was developed using a PS processor LP940H manufactured by Fuji Photo Film Co., Ltd. charged with an alkaline developer A having the following composition, maintained at a development temperature of 28 ° C., and developed for 25 seconds. Went.
<Alkali developer A composition>
・ SiO ₂ · K ₂ O (K ₂ O / SiO ₂ = 1/1 (molar ratio)) 4.0% by mass
・ Citric acid 0.5% by mass
・ Polyethylene glycol modified sorbitol 1.0% by mass
(Average 30 unit adduct)
・ Water 50.0 mass%
-Print-
Each lithographic printing plate after development was continuously subjected to printing using a printing press Lithron manufactured by Komori Corporation. At this time, the number of sheets that can be printed while maintaining a sufficient ink concentration was measured visually to evaluate the printing durability. The larger the number, the better the printing durability. The results are shown in Table 2 below.

(Evaluation of chemical resistance)
The lithographic printing plate precursors of Examples 1 to 4 and Comparative Examples 1 and 2 were exposed, developed and printed in the same manner as in the evaluation of printing durability. At this time, every time 5,000 sheets were printed, a process of wiping the plate surface with a cleaner (manufactured by Fuji Photo Film Co., Ltd., multi-cleaner) was added to evaluate chemical resistance. The larger the number, the better the chemical resistance. The results are shown in Table 2 below.

(Scratch resistance evaluation)
The obtained lithographic printing plate precursors of Examples 1 to 4 and Comparative Examples 1 and 2 were rubbed 15 times with Abrazer felt CS5 under a load of 250 g using a rotary ablation tester (manufactured by TOYOSEIKI).
Then, using a PS processor 940HII manufactured by Fuji Photo Film Co., Ltd. charged with DT-2 manufactured by Fuji Photo Film Co., Ltd. (DT-2: diluted with water = 1: 8), the liquid temperature was kept at 30 degrees. , And developed for 12 s. At this time, the developing electric power was 45 mS / cm. The scratch resistance was evaluated according to the following criteria. The results are shown in Table 2 below.
<Evaluation criteria for scratch resistance>
○: The optical density of the photosensitive film in the rubbed part was not changed at all. Δ: The optical density of the photosensitive film in the rubbed part was slightly observed visually. ×: The optical density of the photosensitive film in the rubbed part was What became 2/3 or less of the non-friction part

(Sharpness of image)
The obtained lithographic printing plate precursors of Examples 1 to 4 and Comparative Examples 1 and 2 were drawn in a test pattern (Staccato 10, 20) in an image form at a beam intensity of 9 w and a drum rotation speed of 150 rpm with a Trend setter manufactured by Creo. I did. Each lithographic printing plate precursor after exposure was loaded with a developer DT-2 (DT-2: diluted with water = 1: 8) manufactured by Fuji Photo Film Co., Ltd. PS processor 940HII manufactured by Fuji Photo Film Co., Ltd. , And the liquid temperature was kept at 30 ° C., and the development time was 12 s. The edge part of the obtained image was observed with an electron microscope (Hitachi S-800, manufactured by Hitachi, Ltd.). The image sharpness evaluation was performed according to the following criteria. The results are shown in Table 2 below.
<Evaluation criteria for image sharpness>
○: Image side is straight Δ: Image side is partially missing ×: Image side 1/2 is missing

As is apparent from Table 2, the lithographic printing plate precursors of Examples 1 to 4 in which a dispersed phase is formed in the lower layer and the lower layer contains a polymer containing maleimide have image sharpness, scratch resistance, and printing durability. As a result, it was confirmed that the material was excellent in chemical resistance and chemical resistance.
On the other hand, the lithographic printing plate precursor of Comparative Example 1 which did not use a specific maleimide polymer was inferior in both printing durability and chemical resistance compared to the examples. Further, it was confirmed that the lithographic printing plate precursor of Comparative Example 2 in which no novolak resin was not used and no dispersed phase was formed in the lower layer had scratch resistance but was inferior in image sharpness.
It was confirmed that the planographic printing plate precursors of Examples 5 to 6 were excellent in image sharpness, scratch resistance, printing durability and chemical resistance.
On the other hand, the planographic printing plate precursor of Comparative Example 3 having a single recording layer was inferior in scratch resistance as compared with the example of the example having a multilayered recording layer.
Further, even when the lithographic printing plate precursor was developed with a silicate developer, the lithographic printing plate precursor of Example 1 using the silicate treated support was not used. As in the case of development with a silicate developer, it was confirmed that excellent image sharpness, scratch resistance, printing durability and chemical resistance were obtained.

It is a schematic block diagram which shows an example of the mechanical roughening apparatus used for preparation of the support body for lithographic printing plate precursors concerning this invention. It is a graph which shows an example of the alternating waveform current waveform figure used for the electrochemical roughening used for preparation of the support body for lithographic printing plate precursors concerning this invention. It is a schematic block diagram of the apparatus which connected the 2 or more radial drum roller used for the electrochemical roughening used for preparation of the support body for lithographic printing plate precursors concerning this invention. It is the schematic of the electrolytic treatment apparatus in the two-stage electric power feeding electrolysis method applicable to preparation of the support body for lithographic printing plate precursors concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum plate 2, 4 Roller-shaped brush 3 Polishing slurry liquid 5, 6, 7, 8 Support roller 11 Aluminum web 12 Radial drum roller 13a, 13b Main electrode 14 Electrolytic process liquid 15a, 15b Electrolyte supply port 16 Slit 17 Electrolyte Passage 18 Auxiliary anodes 19a, 19b Thyristor 20 AC power source 40, 41 Main electrolytic cell 50, 51 Auxiliary anode cell 62a First power feeding unit 62b Second power feeding unit 63a First electrolysis unit 63b Second electrolysis unit 64a, 64b Support roller 65a First One feeding electrode 65b Second feeding electrode 66a, 66b, 66c, 66d Electrolytic electrode 67a, 67b, 67c, 67d Power supply

Claims (1)

  A lithographic printing plate precursor comprising 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, wherein the positive recording layer comprises: Among them, the positive recording layer closest to the support contains at least two kinds of resins, at least one of these resins forms a dispersed phase, and at least one of the resins contains maleimide. A lithographic printing plate precursor characterized by being a polymer.

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