JP2005266133A - Planographic original plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive infrared laser planographic original plate to make a direct printing plate which is excellent in scratch-proof and formed image discrimination. <P>SOLUTION: This original plate is made by stacking two or more positive recording layers which contain resin and an infrared absorption agent, and also increase its solubility to alkaline water by infrared laser exposure on a support. The positive recording layer closest to the support of these recording layers contains onium salt and resin which is water insoluble but alkali soluble. <P>COPYRIGHT: (C)2005,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 be easily obtained with high output and small size. These lasers are very useful as an exposure light source when directly making a plate from digital data such as a computer.
The positive type lithographic printing plate precursor for infrared laser has an alkaline aqueous solution-soluble binder resin and an infrared absorbing dye (IR dye) that absorbs light and generates heat as essential components. In the image area), it acts as a dissolution inhibitor that substantially lowers the solubility of the binder resin by interaction with the binder resin. In the exposed area (non-image area), the generated heat causes the IR dye and the binder resin to react with each other. The interaction weakens and dissolves in an alkaline developer to form a lithographic printing plate.
However, in such a positive lithographic printing plate material for infrared laser, the solubility between the developer in the non-exposed area (image area) and the solubility of the exposed area (non-image area) under various conditions of use. However, there is a problem that over-development and poor development are likely to occur due to fluctuations in use conditions. In addition, even when the surface condition slightly changes due to touching the surface during handling, the unexposed area (image area) dissolves and becomes scratched during development, causing deterioration in printing durability and poor inking properties. There was a problem.

Such a problem originates in 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.
In contrast, 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 alkali developer must be used in advance. In other words, the state before development becomes unstable.

In order to solve the above problems, there has been proposed a method (see Patent Document 1) in which an infrared absorber in a film is unevenly distributed for the purpose of improving image discrimination. Has not reached. 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 area, 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 been proposed (see Patent Document 3).
However, in order to make the recording layer have a multi-layer structure in this way, it is necessary to select resins having different characteristics as the resins used in both layers, and there is a problem that their interactivity is lowered, or Due to the good developability, there is a concern that undesired dissolution will occur at both ends of the lower layer in the image area during development, which may affect printing durability and image reproducibility. There was still room for improvement in order to make full use of it.
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 an infrared laser for direct plate making which is excellent in scratch resistance and formed image discrimination.

As a result of extensive research, the present inventor has provided a positive recording layer having a multilayer structure, and contains a water-insoluble and alkali-soluble polymer compound and a compound having a specific structure in the recording layer close to the support. Thus, the inventors have found that the above problems can be solved, and completed the present invention.
That is, the lithographic printing plate precursor of the present invention comprises, on a support, a resin and an infrared absorber, and has two or more positive recording layers whose solubility in an aqueous alkali solution is increased by infrared laser exposure. Among the positive recording layers, the positive recording layer closest to the support contains a water-insoluble and alkali-soluble resin and an onium salt.

Hereinafter, in this specification, the “positive recording layer closest to the support” is appropriately referred to as “lowermost recording layer”, and the other positive recording layer is referred to as “upper recording layer”.
In the lithographic printing plate precursor according to the invention, in addition to the plurality of positive recording layers, other layers as desired, for example, a surface protective layer, an undercoat layer, an intermediate layer, a backcoat layer, are provided on the support. Can be provided as long as the effects of the present invention are not impaired.

Although the mechanism of action of the lithographic printing plate precursor according to the present invention is not yet clear, it is presumed as follows.
The positive recording layer (lowermost recording layer) closest to the support of the lithographic printing plate precursor according to the invention contains a water-insoluble and alkali-soluble polymer compound and an onium salt as described above. In the present invention, by suppressing the solubility in an alkaline aqueous solution by the action of these compounds in the lowermost recording layer, the resistance of the entire unexposed area (image area) to the alkaline developer is remarkably improved and highly active. High resistance to an alkaline developer can be exhibited. On the other hand, in the exposed area (non-image area), the onium salt is thermally decomposed, so that the solubility of the lowermost recording layer in the alkaline aqueous solution increases, and the permeability of the alkaline aqueous solution into the lowermost recording layer increases. Sometimes when the upper recording layer is removed, the lowermost recording layer is also quickly removed. Therefore, it is considered that the planographic printing plate precursor of the present invention can form a sharp image excellent in image discrimination.
The above-described characteristics of the lithographic printing plate precursor according to the present invention are remarkable in a high-definition image having a small image area, and thus are particularly useful for a high-definition image such as an FM screen that has been used with the recent CTP. . Therefore, the lithographic printing plate precursor of the present invention is a commercially available FM screen such as Staccato (trade name: manufactured by Creo), FAIRDOT, Randot (trade name: manufactured by Dainippon Screen), Co-Re screen (trade name: (Fuji Photo Film) and the like can be used suitably. Note that a high-definition image is one in which 50% area ratio output data is 210 lines or more in terms of perimeter.

  ADVANTAGE OF THE INVENTION According to this invention, the positive type lithographic printing plate precursor for infrared lasers for direct plate-making excellent in scratch resistance and the discrimination of the formed image can be provided.

Hereinafter, the present invention will be described in detail.
The lithographic printing plate precursor according to the present invention comprises, on a support, a resin and an infrared absorber, and has two or more positive recording layers whose solubility in an aqueous alkali solution is increased by infrared laser exposure. The lithographic printing plate precursor, wherein the positive recording layer closest to the support among the recording layers contains a water-insoluble and alkali-soluble resin and an onium salt.

[Positive recording layer]
The positive recording layer in the present invention is a layer containing a resin and an infrared absorber, and an image is formed by increasing the solubility in an alkaline aqueous solution by infrared laser exposure. In the present invention, the positive recording layer closest to the support among the plurality of poly-type recording layers contains an onium salt as an essential component.

[Onium salt]
The onium salt in the present invention will be described in detail.
Examples of onium salts in the present invention include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, azinium salts, and the like. In the present invention, the onium salt functions as a dissolution inhibitor that lowers the solubility of the polymer compound in water or an alkali developer by mixing with the water-insoluble and alkali-soluble polymer compound.

  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).

Moreover, as an onium salt in this invention, the compound represented with the following general formula (A) is still more preferable.
Formula (A) X ^- M ⁺
In general formula (A), X ⁻ represents an anion of a compound represented by the following general formula (B) (for example, an anion obtained by removing a hydrogen atom of —NH— in the compound), or a compound represented by general formula (C) An anion part (R ^C —COO ⁻ ) of M is represented, and M ⁺ represents a counter cation selected from sulfonium, iodonium, diazonium, ammonium and azinium.

In general formula (B), Y represents a single bond, —CO— or —SO ₂ —, and R ^a and R ^b each independently represent a linear, branched or cyclic alkyl group, aryl Represents a group, an aralkyl group, or a camphor group. R ^a and R ^b may be bonded via an alkylene group, an arylene group, or an aralkyl group to form a ring. When Y is a —CO— group, R ^b may be a hydroxyl group or an alkoxy group.

Formula (C) R ^C —COO ⁻ M ⁺
In the general formula (C), R ^C represents an alkyl group or an aryl group, and M ⁺ represents a counter cation selected from sulfonium, iodonium, diazonium, ammonium and azinium.

In General Formula (B), Y represents a single bond, —CO—, or —SO ₂ —. From the viewpoint of sensitivity and stability, Y is preferably —CO—, and the pKa of the compound represented by the general formula (B) is more preferably 0 to 6.
R ^a and R ^b each independently represents a linear, branched or cyclic alkyl group, aryl group, aralkyl group, or camphor group. R ^a and R ^b may be bonded to each other via an alkylene group, an arylene group or an aralkylene group to form a ring. When Y is a —CO— group, R ^b may be a hydroxyl group or an alkoxy group.
R ^a and R ^b preferably represent an alkyl group having 1 to 20 carbon atoms, an aryl group having 1 to 20 carbon atoms, or an aralkyl group having 1 to 20 carbon atoms. These alkyl group, aryl group or aralkyl group may have a substituent. Specific examples of the substituent that can be introduced include an alkyl group, an alkoxy group, an alkenyl group, an aryl group, an alkynyl group, Amino group, cyano group, hydroxyl group, halogen atom, amide group, ester group, carbonyl group, carboxyl group, sulfonic acid group, sulfonamide group, nitro group, etc., which have the above substituents It may be. Further, two or more substituents may be bonded to each other to form a ring, and the ring structure may be a heterocyclic structure containing a nitrogen atom or a sulfur atom.

  Although the specific example of a compound represented by general formula (B) below is illustrated, this invention is not restrict | limited to these.

  More preferable examples of the onium salt having an anion of the compound represented by the general formula (B) in the anion part include compounds represented by the following general formulas (I) and (II). By using such a compound, sensitivity and scratch resistance are further improved. This compound is an anion of the general formulas (I) and (II) by heating, or in the case of an embodiment containing an infrared absorber as in the present invention, by generating heat by irradiating infrared rays. The anion of the compound represented by the general formula (B) corresponding to part decomposes to generate an acid or the like, and the dissolution inhibiting ability is released.

In the above formula, R ^{1 to} R ²⁵ are a hydrogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxy group, a hydroxy group, a halogen atom, or —S—R ^26. Represents a group. Here, R ²⁶ represents a linear, branched or cyclic alkyl group or aryl group. The anion part (X ⁻ ) is an anion of the compound represented by the general formula (B).

In the general formula (I) or the general formula (II), the linear or branched alkyl group represented by R ^{1 to} R ²⁵ may be a methyl group, an ethyl group, or a propyl group that may have a substituent. And a group having 1 to 4 carbon atoms such as a group, n-butyl group, sec-butyl group and t-butyl group. Examples of the cyclic alkyl group include those having 3 to 8 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group, which may have a substituent.
Examples of the alkoxy group represented by R ^{1 to} R ²⁵ include 2 carbon atoms such as a methoxy group, an ethoxy group, a hydroxyethoxy group, a propoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, and a t-butoxy group. There are ~ 4.
Examples of the halogen atom represented by R ^{1 to} R ²⁵ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the aryl group represented by R ²⁶ include those having 6 to 14 carbon atoms such as a phenyl group, a tolyl group, a methoxyphenyl group, and a naphthyl group. The aryl group may have a substituent.
Preferred substituents that the group represented by R ^{1 to} R ²⁵ may have include an alkoxy group having 1 to 4 carbon atoms, a halogen atom (fluorine atom, chlorine atom, iodine atom), and 6 to 10 carbon atoms. Examples include an aryl group, an alkenyl group having 2 to 6 carbon atoms, a cyano group, a hydroxy group, a carboxy group, an alkoxycarbonyl group, and a nitro group.

M ⁺ preferably represents a counter cation selected from sulfonium, iodonium, diazonium, ammonium and azinium.
Here, azinium has an azine ring which is a six-membered ring containing a nitrogen atom in its structure, and includes pyridinium, diazinium, and triazinium. Azinium includes one or more aromatic rings condensed with an azine ring, and includes, for example, quinolinium, isoquinolinium, benzoazinium, naphthazinium, and the like. Specifically, for example, described in U.S. Pat. No. 4,743,528, JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, and JP-B-46-42363. And counter cations that form 1-methoxy-4-phenylpyridinium tetrafluoroborate, N-alkoxypyridinium salts, and the like.

Among these counter cations, a compound having iodonium or sulfonium as a counter cation is preferable from the viewpoint of stability and sensitivity, and a compound having a diaryliodonium or triarylsulfonium skeleton is more preferable.
Specific examples of the compound having an anion of the compound represented by the general formula (B) as the anion moiety among the compounds represented by the general formula (A), which are onium salts in the present invention, are preferable Although shown in combination with a cation moiety corresponding to a cation, the present invention is not limited to this.

A preferable structure of the sulfonium skeleton is preferably a triarylsulfonium skeleton from the viewpoint of sensitivity and stability, and the aryl group may be substituted in the same manner as the above-mentioned aryl group.
Examples of preferable sulfonium salts, that is, dissolution inhibitors represented by the general formula (I) include the following exemplified compounds (I-1) to (I-28).

Moreover, as a preferable structure of the iodonium skeleton, a diaryl iodonium skeleton is preferable from the viewpoint of stability, and the aryl group may be substituted in the same manner as the aryl group described above.
Preferred examples of the iodonium salt, that is, the compound represented by the general formula (II) include the following exemplified compounds (II-1) to (II-15).

  A typical synthesis example of a compound represented by the general formula (A) and having the anion of the compound represented by the general formula (B) as an anion part is disclosed in Japanese Patent Application 2000 previously proposed by the present applicant. No. 184603, paragraph numbers [0039] to [0043].

Next, the case where the anion part of the onium salt is the anion part (R ^C —COO ⁻ ) of the compound represented by the following general formula (C) will be described.
Formula (C) R ^C —COO ⁻ M ⁺
In general formula (C), R ^C preferably represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 1 to 20 carbon atoms. R ^C may have a ring structure. These alkyl groups or aryl groups may have a substituent. Specific examples of the substituent that can be introduced include an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group, an amino group, and a cyano group. A group, a hydroxyl group, a halogen atom, an amide group, an ester group, a carbonyl group, a carboxyl group, and the like, and these may further have a substituent as described above. Further, two or more substituents may be bonded to each other to form a ring, and the ring structure may be a heterocyclic structure containing a nitrogen atom or a sulfur atom.
The compound represented by the general formula (C) preferably has a pKa in water of 2 or more, and further preferably has a pKa of 3 or more. If the pKa in water is 2 or more, the thermal decomposition temperature as a dissolution inhibitor tends to decrease, which is considered to contribute to the improvement of sensitivity.

Further, M ⁺ has the same meaning as described above, and the same preferable examples can be given.
Specific examples of the compound (dissolution inhibitor) having the anion moiety of the compound represented by the general formula (C) as a counter anion are shown below in combination with a cation moiety corresponding to a preferred counter cation. Is not limited to this.
A preferred structure of the iodonium skeleton is preferably a diarylsulfonium skeleton from the viewpoint of stability, and the aryl group may be substituted in the same manner as the aryl group described above. First, preferred iodonium salt (with iodonium as a counter cation) compound [Exemplary Compound (IA-1) to Exemplified Compound (IJ-8)] will be exemplified.

  A preferable structure of the sulfonium skeleton is preferably a triarylsulfonium skeleton from the viewpoint of sensitivity and stability, and the aryl group may be substituted in the same manner as the above-mentioned aryl group. Next, preferred sulfonium salt (with sulfonium as a counter cation) compound [Exemplary Compound (SA-1) to Exemplified Compound (SJ-12)] are exemplified.

Examples of the carboxylic acid (R—COOH) suitable for forming the anion moiety (R—COO ⁻ ) in the compound represented by the general formula (C) are shown below.

  A typical synthesis example of the compound represented by the general formula (A) and having an anion moiety in the general formula (C) is a paragraph of the specification of Japanese Patent Application No. 2000-160323 previously proposed by the present applicant. Nos. [0057] to [0060].

In the present invention, the content of the onium salt contained in the lowermost recording layer is 0 with respect to the mass of the total solids constituting the lowermost recording layer from the viewpoint of achieving both film-forming properties and a dissolution inhibiting effect. 0.1-30 mass% is preferable, More preferably, it is 0.3-15 mass%.
The onium salt described above is contained as an essential component in the lowermost recording layer, but may be contained in both the lowermost recording layer and the upper recording layer.

  Next, the resin and infrared absorber constituting the positive recording layer in the present invention will be described in detail.

〔resin〕
In the present invention, as the resin constituting the positive recording layer, a water-insoluble and alkaline water-soluble resin (hereinafter, appropriately referred to as an alkaline water-soluble resin) is used.
The lowermost recording layer in the present invention contains the alkaline water-soluble resin and the onium salt as essential components.

  The alkaline water-soluble resin includes a homopolymer containing an acidic group in the main chain and / or side chain in the resin, a copolymer thereof, or a mixture thereof. Accordingly, the positive recording layer according to the present invention has a property of dissolving when contacted with an alkaline developer.

  The alkali-soluble resin used for the positive recording layer in the present invention is not particularly limited as long as it is a conventionally known one, but any of (1) phenolic hydroxyl group, (2) sulfonamide group, and (3) active imide group A resin having such a functional group in the molecule is preferable. For example, the following are exemplified, but the present invention is not limited to these.

  (1) Examples of the resin 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-, Or any of m- / p-mixing) and novolak resins such as mixed formaldehyde resins and pyrogallol acetone resins. In addition to this, a resin having a phenolic hydroxyl group in the side chain is preferably used as the resin having a phenolic hydroxyl group. As the resin having a phenolic hydroxyl group in the side chain, a polymerizable monomer composed of a low molecular weight compound having at least one unsaturated bond polymerizable with the phenolic hydroxyl group is homopolymerized, or another polymerizable monomer is added to the monomer. Examples thereof include resins obtained by copolymerization.

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

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

(3) The alkali-soluble resin having an active imide group preferably has an active imide group in the molecule, and the resin has at least one unsaturated bond polymerizable with the active imide group in one molecule. Examples thereof include a resin obtained by homopolymerizing a polymerizable monomer composed of a low molecular compound, 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, the alkali-soluble resin of the present invention is a resin obtained by polymerizing 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. Alternatively, it is preferable to use a resin obtained by copolymerizing these two or more polymerizable monomers with another polymerizable monomer. When the polymerizable monomer having a phenolic hydroxyl group is copolymerized with a polymerizable monomer having a sulfonamide group and / or a polymerizable monomer having an active imide group, the blending mass ratio of these components is 50:50 to 5: It is preferably in the range of 95, particularly preferably in the range of 40:60 to 10:90.

  In the present invention, the alkali-soluble resin 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 the case, from the viewpoint of alkali solubility, the monomer that imparts 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.

  In the present invention, those having a phenolic hydroxyl group are preferred as the alkaline water-soluble resin in that the image-forming property upon exposure with an infrared laser or the like is excellent. Further, as the alkaline water-soluble resin having a phenolic hydroxyl group, as described in US Pat. No. 4,123,279, the number of carbon atoms such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin can be used. A condensation polymer of phenol and formaldehyde having 3 to 8 alkyl groups as substituents can also be used.

  As a copolymerization method of the alkaline water-soluble resin, a conventionally known graft copolymerization method, block copolymerization method, random copolymerization method, or the like can be used.

  Among the positive recording layers, the alkali-soluble resin used for the upper recording layer is phenolic in that strong hydrogen bonding occurs in the unexposed area and some hydrogen bonds are easily released in the exposed area. A resin having a functional hydroxyl group is desirable, and a novolak resin is more preferable. Further, those having a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000 are preferred.

  On the other hand, among the positive recording layers, the alkali-soluble resin used for the lowermost recording layer is preferably an acrylic resin, and more preferably an acrylic resin having a sulfoamide group.

These alkali-soluble resins may be used alone or in combination of two or more.
Further, the content of the alkali-soluble resin is 40 to 99% by mass, preferably 45 to 95% by mass, particularly preferably 50% in the total solid content of the positive recording layer from the viewpoint of durability and sensitivity of the positive recording layer. It is -90 mass%.

[Infrared absorber]
The positive recording layer of the present invention contains an infrared absorber that exhibits a photothermal conversion function. This infrared absorber has a function of converting the absorbed infrared rays into heat, and the release of the interaction, decomposition of the development inhibitor, generation of acid, etc. occur in the positive recording layer by infrared laser scanning, 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.
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.

Below, the infrared absorber contained in a positive recording layer is explained in full detail.
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 as formulas (I) and (II) in US Pat. No. 4,756,993.

  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 In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used.

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

  The pigment particle size is preferably in the range of 0.01 μm to 10 μm, and more preferably in the range of 0.05 μm to 1 μm, from the viewpoint of the stability of the pigment dispersion and the uniformity of the positive recording layer. In particular, it is preferably in the range of 0.1 μm to 1 μm.

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

In the present invention, a positive action (dissolution in the alkaline developer is suppressed in the unexposed area and the dissolution inhibiting action is canceled in the exposed area) is caused by the interaction with the binder polymer having a specific functional group. Infrared absorbers are preferably used, and those having an onium salt structure are particularly preferable in that respect. 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.
Examples of infrared absorbers having an onium salt structure include those described in paragraph numbers [0018] to [0034] of JP-A No. 11-291651.

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, -Gb represents a neutral substituent. X ^{m +} represents a 1 to m-valent cation containing a proton, and m represents an integer of 1 to 6. Can be mentioned.

  In the positive recording layer according to 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 content of the infrared absorber is in the range of 0.01 to 50% by mass with respect to the total solid content of the positive recording layer, from the viewpoints of image formability and suppression of occurrence of contamination in non-image areas. Is more preferable, 0.1 to 20% by mass, still more preferably 0.5 to 15% by mass.

[Additive]
In the positive recording layer of the present invention, various known additives can be used in combination with the above components, depending on the purpose.

(Fluorine-containing polymer)
In the positive recording layer of the present invention, a fluorine-containing polymer is preferably added for the purpose of improving the development resistance of the image area. Examples of the fluorine-containing polymer to be used include copolymers comprising fluorine-containing monomers 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 a fluorine-containing acrylic monomer of A33 with an arbitrary acrylic monomer can be exemplified.
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, which is a compound having the above preferred molecular weight, can also be used. As specific examples, MegaFuck F-171, F-173, F-176, F-183, F-184, F-780, F-781 (all trade names) manufactured by Dainippon Ink & Chemicals, Inc. are used. Can be mentioned.
These fluorine-containing polymers may be used alone or in combination of two or more.
The addition amount is preferably 1.4% by mass or more based on the total solid content of the positive recording layer from the viewpoint of development resistance and sensitivity of the image area, and is preferably 1.4 to 5.0% by mass. % Is more preferable.

(Other dissolution inhibitors)
The positive recording layer in the present invention is further thermally decomposable, such as an o-quinonediazide compound, an aromatic sulfone compound, and an aromatic sulfonic acid ester compound, if necessary, and is soluble in an alkaline water-soluble resin when not decomposed. Can be used in combination with a substance (other dissolution inhibitor) that substantially lowers the pH. 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.

  As the o-quinonediazide compound used in the present invention, compounds having various structures which are compounds having at least one o-quinonediazide group and which increase alkali solubility by thermal decomposition can be used. That is, the o-quinonediazide compound loses the ability to suppress dissolution of the alkali-soluble resin by thermal decomposition, and the solubility of the positive-type recording layer is due to both the effect of the o-quinonediazide compound itself changing to an alkali-soluble substance. Help.

  Specific examples of the o-quinonediazide compound include J.I. The compounds described in pages 339 to 352 of “Light Sensitive Systems” (John Wiley & Sons. Inc.) by Korser can be used, and in particular, o reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. -Sulfonic acid esters or sulfonic acid amides of quinonediazides are preferred. Further, benzoquinone (1,2) -diazidosulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide- described in US 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, JP-B-41-11222, JP-B-45-9610, JP-B-49-17481, US 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. 1,005, 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 the positive recording layer. .
These compounds can be used alone, but may be used as a mixture of several kinds.
Moreover, the addition amount of dissolution inhibitors 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.

(Other additives)
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 may be added.

Further, for the purpose of further improving the sensitivity, cyclic acid anhydrides, phenols, and organic acids can be added.
Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and 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.

Examples of organic acids include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid , P-toluic acid, 3,4-methoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like.
The addition ratio of the cyclic acid anhydride, phenols and organic acids to the positive recording layer is preferably 0.05 to 20% by mass, more preferably 0.1 to 5% by mass, and particularly preferably 0.1 to 5% by mass. 10% by mass.

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

By adding these dyes, the distinction between the image area and the non-image area becomes clear after the image formation.
In addition, the addition amount of these dyes has the preferable range of 0.01-10 mass% with respect to the total solid of a positive recording layer.

  Further, in the positive recording layer of the present invention, a nonionic interface as described in JP-A-62-251740 and JP-A-3-208514 is used in order to broaden the processing stability against development conditions. Activators, 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 Fluoropolymers as described in the publication can be added.

Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like.
Specific examples of the double-sided activator include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Co., Ltd.).
As the siloxane compound, a block copolymer of dimethylsiloxane and polyalkylene oxide is preferable. Specific examples include DBE-224, DBE-621, DBE-712, DBP- manufactured by Chisso Corporation. And polyalkylene oxide-modified silicones such as 732, DBP-534, and Tego Glide 100 manufactured by Tego, Germany.
The addition ratio of the nonionic surfactant, amphoteric surfactant, siloxane compound, or fluoropolymer to the positive recording layer is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass. is there.

In the positive recording layer of the present invention, a print-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.

[Formation of multiple positive recording layers]
The positive recording layer in the present invention is usually formed by sequentially coating the lower recording layer coating solution obtained by dissolving each of the above components in a solvent, and further the upper recording layer coating solution on an appropriate support. can do.
Here, suitable solvents for the lower recording layer coating solution and the upper recording layer coating solution 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 and the like can be mentioned but are not limited thereto. These solvents are used alone or in combination.
The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass.

  In addition, a plasticizer is added to both the coating liquids as necessary to make the coating film flexible. 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.

  Furthermore, a surfactant for improving the coating property, for example, a fluorine-based surfactant as described in JP-A-62-170950 can be added to both the above coating solutions. . A preferable addition amount is 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass, based on the total solid content of the coating solution.

In the present invention, it is preferable that the lowermost recording layer and the upper recording layer in contact with the lowermost recording layer are formed in principle separated from each other.
As a method for forming both layers separately, for example, a method using a difference in solvent solubility between a component contained in the lowermost recording layer and a component contained in the upper recording layer, or the lowermost recording layer Examples include, but are not limited to, a method of rapidly drying and removing the solvent after applying the upper recording layer in contact with the substrate.

As a method of utilizing the difference in solvent solubility between the component contained in the lowermost recording layer and the component contained in the upper recording layer, it is contained in the lowermost recording layer when the upper recording layer coating liquid is applied. And a method using a solvent that does not dissolve the alkali-soluble resin or the specific polymer. 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, first, as the lowermost recording layer component, a component insoluble in a solvent such as methyl ethyl ketone or 1-methoxy-2-propanol that dissolves the alkali-soluble resin that is the upper recording layer component is selected. The lowermost recording layer is formed by applying and drying the coating solution using a solvent system that dissolves. Thereafter, the upper recording layer component is dissolved in methyl ethyl ketone, 1-methoxy-2-propanol or the like to prepare a coating solution, which can be formed into two layers by coating and drying on the lowermost recording layer. .

  When applying the upper recording layer coating solution, when using a method that uses a solvent that does not dissolve the alkali-soluble resin or onium salt contained in the lowermost recording layer, the lowermost recording layer is used as the upper recording layer coating solvent. A solvent that dissolves the alkali-soluble resin or onium salt contained in the solvent and a solvent that does not dissolve may be used in combination. By changing the mixing ratio of the two solvents, interlayer mixing between the upper recording layer and the lowermost recording layer can be arbitrarily controlled. When the ratio of the solvent that dissolves the alkali-soluble resin or onium salt in the lowermost recording layer increases, a part of the lowermost recording layer dissolves when the upper recording layer is applied, and after drying, the particles form in the upper recording layer. It is contained as a component, and this particulate component makes a protrusion on the surface of the upper recording layer and improves scratch resistance. On the other hand, when the lowermost recording layer component is dissolved into the upper recording layer, the film quality of the lowermost recording layer is lowered and the chemical resistance tends to be lowered. In this way, by controlling the mixing ratio in consideration of each physical property, various characteristics can be expressed, and further, partial compatibility between layers described later can be caused.

  From the viewpoint of the effect of the present invention, when the above mixed solvent is used as the coating solvent for the upper recording layer, the solvent for dissolving the alkali-soluble resin or onium salt in the lowermost recording layer is 80 mass of the upper recording layer coating solvent. % Or less is preferable from the viewpoint of chemical resistance, and in view of scratch resistance, it is preferably in the range of 10 to 60% by mass.

  Next, after applying the upper recording layer in contact with the lowermost recording layer, the solvent can be dried very quickly by blowing high-pressure air from a slit nozzle installed substantially perpendicular to the web running direction, It can be achieved by applying thermal energy as conduction heat from the lower surface of the web from a roll (heating roll) supplied inside with a heating medium such as the above or a combination thereof.

Various methods can be used as a method for applying both recording layers in the present invention. For example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, roll coating. Etc.
In particular, in order to prevent damage to the lowermost recording layer when the upper recording layer is applied, the upper recording layer application method is preferably a non-contact type. Although it is a contact type, it is possible to use bar coater coating as a method generally used for solvent-based coating, but it is desirable to apply by forward driving to prevent damage to the lowermost recording layer. .

The coating amount after drying of the lowermost recording layer in the lithographic printing plate precursor according to the invention is in the range of 0.5 to 1.5 g / m ² from the viewpoint of ensuring printing durability and suppressing residual film formation during development. Is more preferable, and the range of 0.7 to 1.0 g / m ² is more preferable.
Further, the coating amount after drying of the upper recording layer is preferably in the range of 0.05 to 1.0 g / m ² (in the case of two or more layers, the total amount), more preferably 0.07. It is in the range of ˜0.7 g / m ² .
In each of these recording layers, the apparent sensitivity generally increases as the coating amount decreases, 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 near the support is lowered.

[Support]
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 different 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 an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodization treatment to enhance the water retention and wear resistance of the surface as desired. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

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

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

[Undercoat layer]
The lithographic printing plate precursor according to the invention is provided by laminating at least two layers of a lowermost recording layer and an upper recording layer on a support, and if necessary, between the support and the lowermost recording layer. An undercoat layer can be provided.
Various organic compounds are used as the primer layer component. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, and phenylphosphonic acid which may have a substituent Organic phosphonic acids such as naphthyl phosphonic acid, alkyl phosphonic acid, glycero phosphonic acid, methylene diphosphonic acid and ethylene diphosphonic acid, phenyl phosphoric acid, naphthyl phosphoric acid, alkyl phosphoric acid and glycerophosphoric acid which may have a substituent Organic phosphoric acid, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid, glycerophosphinic acid and other organic phosphinic acids, glycine and β-alanine amino acids, and triethanolamine hydrochloric acid Has a hydroxy group such as salt -Alanine, and hydrochlorides of amines that may be used in combination of two or more.

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

[Plate making]
The lithographic printing plate precursor according to the invention having the positive recording layer and other layers as described above is usually subjected to image exposure and development treatment.

[(Image) exposure]
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, exposure is preferably performed with a light source having a light emission wavelength from the near infrared region to the infrared region, and specifically, image exposure is performed with a solid-state laser and a semiconductor laser emitting infrared light having a wavelength of 760 nm to 1200 nm. It is preferable.

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

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

These non-reducing sugars can be used alone or in combination of two or more thereof, and the proportion of the non-reducing sugar in the developer is preferably 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. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are also used.

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

In addition, various surfactants and organic solvents may be added to the developer and replenisher as necessary for the purpose of promoting or suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area. Can do. Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants.
Furthermore, reducing agents such as sodium salt and potassium salt of inorganic acids such as hydroquinone, resorcin, sulfurous acid, and bisulfite, as well as organic carboxylic acids, antifoaming agents, and water softeners are added to the developer and replenisher as necessary. Can also be added.

  The lithographic 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. As the post-treatment of the planographic printing plate of the present invention, these treatments can be used in various combinations.

2. Description of the Related Art In recent years, automatic developing machines for lithographic printing plate precursors 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 conveying a printing plate, processing liquid tanks, and a spray device. Each of the pumps pumped by a pump while horizontally conveying an exposed printing plate. A developing solution is sprayed from a spray nozzle. 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.
When developing using this automatic developing machine, by adding an aqueous solution (replenisher) having a higher alkali strength than the developer to the developer, without changing the developer in the developer tank for a long time, It is known that a large amount of lithographic printing plate precursor can be processed. This replenishment method is also preferably applied in the present invention.

  Further, as described above, in the lithographic printing plate obtained by subjecting the lithographic printing plate precursor of the present invention to image exposure, development, washing and / or rinsing and / or gumming, an unnecessary image portion ( For example, if there is a film edge mark of the original image film, unnecessary image portions are erased. Such erasing is preferably performed by applying an erasing solution to an unnecessary image portion as described in Japanese Patent Publication No. 2-13293, 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 is subjected to a burning treatment in the case of imparting a higher printing durability.
In the case of burning a lithographic printing plate, before burning, an adjustment as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 is used. It is preferable to treat with a surface liquid.
As its method, with a sponge or absorbent cotton soaked with the surface-adjusting liquid, it is applied onto a lithographic printing plate, or a method in which the printing plate is immersed and applied in a vat filled with the surface-adjusting liquid, Application by an automatic coater is applied. Further, it is more preferable to make the coating amount uniform with a squeegee or a squeegee roller after coating.
In general, the amount of surface-adjusting solution applied is suitably 0.03 to 0.8 g / m ² (dry mass). The lithographic printing plate coated with the surface-adjusting solution is dried if necessary, and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). The In this case, the heating temperature and time are in the range of 180 to 300 ° C. and preferably in the range of 1 to 20 minutes, although depending on the type of components forming the image.

  The lithographic printing plate subjected to the burning treatment can be subjected to conventional treatments such as washing and gumming as needed, but a surface-conditioning solution containing a water-soluble polymer compound is used. If so, so-called desensitizing treatment such as gumming can be omitted.

  The planographic printing plate obtained as described above 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.

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

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

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

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

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

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10.5 g / L aqueous solution of nitric acid (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions) at a liquid temperature of 80 ° C.
The 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) The etching process by spraying was performed at 32 ° C. using an aqueous solution of alkali etching treatment%, the aluminum plate was dissolved at 0.20 g / m ² , and the electrochemical surface roughening treatment was performed using the alternating current of the previous stage. Occasionally, the generated smut component mainly composed of aluminum hydroxide was removed, and the edge portion of the generated pit was dissolved to smooth the edge portion. Then, water washing by spraying was performed.

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

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

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

[Formation of undercoat layer]
On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat solution having the following composition was applied and dried at 80 ° C. for 15 seconds to form a coating film. The coating amount of the coating film after drying was 15 mg / m ² .
<Undercoat liquid composition>
・ The following polymer compound 1 0.3g
・ Methanol 100g
・ Water 1g

After applying the following coating solution for the lowermost recording layer to the obtained substrate so that the coating amount becomes 0.85 g / m ² , Wind Control is set to 7 at 140 ° C. with PERFECT OVEN PH200 manufactured by TABAI. Then, the upper image recording layer coating solution was applied so that the coating amount was 0.15 g / m ^2, and then dried at 120 ° C. for 1 minute to obtain a lithographic printing plate precursor 1.

[Coating solution for the bottom recording layer]
N- (4-aminosulfonylphenyl) methacrylamide / acrylonitrile / methyl methacrylate (36/34/30: weight average molecular weight 100,000, acid value 2.65) 2.13 g
-Onium salt (dissolution inhibitor: the following compound 1) 0.20 g
・ Cyanine dye A (the following structure: mixed system) 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.125g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.030 g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Fluorosurfactant (Surface improving surfactant) 0.035 g
[Megafuck F781F, manufactured by Dainippon Ink & Chemicals, Inc.]
・ Methyl ethyl ketone 24.38g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-Butyrolactone 14.2g

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

(Example 2)
A lithographic printing plate precursor 2 was obtained in the same manner as in Example 1 except that the lowermost recording layer coating solution used in Example 1 was changed to the following.

[Coating solution for the bottom recording layer]
N- (4-aminosulfonylphenyl) methacrylamide /
Acrylonitrile / methyl methacrylate 1.92 g
M, p-cresol novolak (m / p ratio = 6/4, weight average molecular weight 4500, containing 0.8% by mass of unreacted cresol)
0.192g
-Compound 1 0.20g
・ Cyanine dye A (said structure: mixed system) 0.109 g
・ 4,4′-bishydroxyphenylsulfone 0.123 g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Fluorosurfactant (Surface improving surfactant) 0.035 g
[Megafuck F781F, manufactured by Dainippon Ink & Chemicals, Inc.]
・ Methyl ethyl ketone 24.38g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-Butyrolactone 14.2g

(Example 3)
A lithographic printing plate precursor 3 was obtained in the same manner as in Example 1 except that the lowermost recording layer coating solution used in Example 1 was changed to the following.

[Coating solution for the bottom recording layer]
N- (4-aminosulfonylphenyl) methacrylamide /
Acrylonitrile / methyl methacrylate (36/34/30: weight average molecular weight 100,000, acid value 2.65) 2.13 g
・ The following compound 2 0.18 g
・ Cyanine dye C (the following structure) 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ P-toluenesulfonic acid 0.130 g
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Methyl ethyl ketone 25.38g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-butyrolactone 13.2 g

Example 4
A lithographic printing plate precursor 4 was obtained in the same manner as in Example 1 except that the application amount of the upper recording layer in Example 1 was 0.20 g / m ² .

(Example 5)
In the production of the support of Example 1, (h) alkali metal silicate treatment is not performed, (i) in the formation of the undercoat layer, an undercoat solution having the following composition is applied, dried at 80 ° C. for 30 seconds, and dried. A lithographic printing plate precursor 5 was obtained in the same manner as in Example 1 except that the subsequent coating amount was 10 mg / m2.

<Undercoat liquid composition>
・ Β-Alanine 0.1g
・ Phenylsulfonic acid 0.05g
・ Methanol 40g
・ Pure water 60g

(Example 6)
In Example 1, a lithographic printing plate precursor 6 was obtained in the same manner as in Example 1 except that the support prepared as described below was used.

[Production of support]
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 by using an aluminum alloy of Al and inevitable impurities. 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. Created. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, it was kept soaked at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Further, after heat treatment was performed at 500 ° C. using a continuous annealing machine, an aluminum plate having a thickness of 0.30 mm was finished by cold rolling. After making this aluminum plate 1030 mm in width, the following surface treatment was continuously performed.

(A) Mechanical roughening treatment (brush grain method)
While supplying an aqueous suspension (specific gravity 1.1 g / cm 3) of an abrasive (pumice) as a polishing slurry liquid to the surface of the aluminum plate, a mechanical surface roughening treatment was performed with a rotating roller brush. The median diameter of the abrasive was 33 μm. As for the roller-like brush, a nylon brush was planted so as to be dense by making a hole in a stainless steel cylinder having a diameter of 400 mm. The material of the nylon brush was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The distance between the surfaces of the two support rollers (φ250 mm) under the brush was 300 mm. The roller brush was pressed until the load of the drive motor for rotating the brush became 10 kW plus with respect to the load before the roller brush was pressed against the aluminum plate.

(B) Etching treatment with alkali agent The aluminum plate after the mechanical surface-roughening treatment obtained above is sprayed with an aqueous caustic soda solution having a caustic soda concentration of 2.6 mass% and an aluminum ion concentration of 5 mass%, so that the aluminum dissolution amount is 10 g. Etching was performed at / m ² . Then, water washing by spraying was performed. The temperature for the alkali etching treatment was 70 ° C.

(C) Desmutting treatment The desmutting treatment was performed by spraying with a 1% by mass aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by mass of aluminum ions), and then washed with water by spraying.

(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% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 35 ° C.
The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 197 C / dm ^{2 as} the total amount of electricity when the aluminum plate was the anode.
Then, water washing by spraying was performed.

(E) Alkali etching treatment An aluminum plate was subjected to aging treatment by spraying at a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at 70 ° C. to dissolve the aluminum plate by 3.8 g / m ² . Then, water washing by spraying was performed.

  A desmut treatment was performed by spraying with a 1% by mass aqueous solution of nitric acid having a nitric acid concentration of 30 ° C. (containing 0.5% by mass of aluminum ions), followed by washing with water by spraying.

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The liquid temperature was 40 ° C. The AC power supply waveform is the waveform shown in FIG. 1. The time TP until the current value reaches the peak from zero is 0.8 msec, the duty ratio is 1: 1, and a trapezoidal rectangular wave AC is used with the carbon electrode as the counter electrode. An electrochemical roughening treatment was performed. Ferrite was used for the auxiliary anode.
The current density was 25 A / dm ² at the peak current value.
The electrolytic solution used for hydrochloric acid electrolysis was a 5.0% by mass aqueous solution of hydrochloric acid (including 5.0% by mass of aluminum ions). The amount of electricity in hydrochloric acid electrolysis was 60 C / It was dm ^2. The electrolytic layer shown in FIG. 2 was used.
Then, water washing by spraying was performed.

(H) Alkali etching treatment sodium hydroxide concentration of 4.5 wt%, by spraying an aluminum ion concentration of 0.5 wt% sodium hydroxide aqueous solution, an aluminum dissolution amount 0.16 g / m ² was subjected to etching treatment. Then, water washing by spraying was performed. The temperature for the alkali etching treatment was 70 ° C. Then, water washing by spraying was performed.

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

(J) Anodizing treatment Anodizing device of two-stage feeding electrolytic treatment method (first and second electrolytic section length 6 m each, first and second feeding section length 3 m each, first and second feeding electrode length 2.4 m each) Anodizing was performed using this.
Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 15% by mass (containing 0.5% by mass of aluminum ions) and a temperature of 38 ° C. Then, water washing by spraying was performed. The final oxide film amount was 2.5 g / m ² .

(K) Formation of undercoat layer On the aluminum support after the alkali metal silicate treatment obtained as described above, the same undercoat liquid as used in Example 1 was applied, and then at 80 ° C for 15 seconds. Dried to form a coating film. The coating amount of the coating film after drying was 15 mg / m ² .

(Comparative Example 1)
A lithographic printing plate precursor 7 was obtained in the same manner as in Example 1 except that the coating liquid for the lowermost recording layer in Example 1 was changed to the following composition.

[Coating solution for the bottom recording layer]
N- (4-aminosulfonylphenyl) methacrylamide /
Acrylonitrile / methyl methacrylate (36/34/30: weight average molecular weight 100,000, acid value 2.65) 2.133 g
・ Cyanine dye A (the above structure) 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-methoxy-4-diazofudiphenylamine
Hexafluorophosphate 0.030g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Fluorine-based surfactant (surfactant with improved coating surface) 0.035 g
[Megafuck F176 (20%), manufactured by Dainippon Ink & Chemicals, Inc.]
・ Methyl ethyl ketone 25.38g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-butyrolactone 13.2 g

(Comparative Example 2)
A lithographic printing plate precursor 8 was obtained in the same manner as in Example 1 except that the coating liquid for the lowermost recording layer in Example 1 was changed to the following composition.

[Coating solution for the bottom recording layer]
N- (4-aminosulfonylphenyl) methacrylamide /
Acrylonitrile / methyl methacrylate (36/34/30: weight average molecular weight 100,000, acid value 2.65) 1.92 g
M, p-cresol novolak (m / p ratio = 6/4, weight average molecular weight 4500, containing 0.8% by mass of unreacted cresol)
0.192g
・ Cyanine dye A (the above structure) 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Fluorine-based surfactant (surfactant with improved coating surface) 0.035 g
[Megafuck F176 (20%), manufactured by Dainippon Ink & Chemicals, Inc.]
・ Methyl ethyl ketone 25.38g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-butyrolactone 13.2 g

[Evaluation of lithographic printing plate precursor]
1. Evaluation of development latitude The lithographic printing plate precursors 1 to 6 of the obtained examples and the lithographic printing plate precursors 7 and 8 of the comparative examples were imaged in a test pattern at a beam intensity of 9 W and a drum rotation speed of 150 rpm using a Trend setter manufactured by Creo. I drew on.
First, a PS processor 940HII manufactured by Fuji Photo Film Co., Ltd., in which the lithographic printing plate precursors 1 to 8 exposed under the above conditions were prepared by changing the dilution ratio of the developer DT-2 manufactured by Fuji Photo Film Co., Ltd. The liquid temperature was maintained at 30 ° C., and development was performed for 12 seconds. At this time, it was confirmed whether there was any stain or coloring due to a defective recording layer remaining film, and the conductivity of the developer that was able to be developed satisfactorily was measured.
The results are shown in the table. Those having a large difference between the upper limit value and the lower limit value are evaluated as being excellent in development latitude.

2. Evaluation of scratch resistance The lithographic printing plate precursors 1 to 6 of the obtained examples and the lithographic printing plate precursors 7 and 8 of the comparative examples were subjected to a rotary ablation tester with a beam intensity of 9 W and a drum rotation speed of 150 rpm using a Trend setter manufactured by Creo. Using TOYOSEIKI Co., Ltd.), it was rubbed 15 times with Abrazer felt CS5 under a load of 250 g.
After that, a modified version of the developer DT-2 manufactured by Fuji Photo Film Co., Ltd. was charged with DT-2 (DT-2: diluted with water = 1: 8). Using a PS processor 940HII manufactured by Fuji Photo Film Co., Ltd., the liquid temperature was maintained at 30 ° C., and development was performed for 12 seconds. At this time, the developing electric power was 45 mS / cm. The scratch resistance was evaluated according to the following criteria. O and Δ are levels that are not problematic in practice. The results are shown in Table 1.
<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

3. Sharpness of the image The lithographic printing plate precursors 1 to 6 of the obtained examples and the lithographic printing plate precursors 7 and 8 of the comparative examples were tested with a test pattern (Staccato 10, 20) was drawn in an image. Fuji Photo Film Co., Ltd. was charged with the lithographic printing plate precursors 1 to 8 exposed under the above-described conditions and the developer DT-2 (DT-2: diluted with water = 1: 8) manufactured by Fuji Photo Film Co., Ltd. ) Using a PS processor 940HII manufactured by), the liquid temperature was kept at 30 ° C., and the development was performed for 12 seconds. 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. O is a level that does not cause any practical problems. The results are shown in Table 1.
<Evaluation criteria for scratch resistance>
○: The image has a straight side. Δ: The image has a part of the side that is slightly missing. X: The image has a half of the side.

As is clear from Table 1, the planographic printing plate precursors of Examples 1 to 6 containing an onium salt and an alkali-soluble resin in the lowermost recording layer are different from the planographic printing plate precursors of Comparative Examples 1 and 2 in the present invention. It can be seen that each of the lithographic printing plate precursors is excellent in development latitude and maintains a sharp image while maintaining good scratch resistance with no practical problems.
On the other hand, the lithographic printing plate precursor 7 of Comparative Example 1 produced in the same manner as in Example 1 except that the lowermost recording layer does not contain an onium salt is a lithographic printing plate precursor inferior in image sharpness and development latitude. It was. Further, the planographic printing plate precursor 8 of Comparative Example 2 was compatible at the interface with the lowermost recording layer when the upper recording layer was applied, and became a recording layer similar to a single layer. All of the scratch resistances were bad compared to the planographic printing plate precursors of the examples.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Aluminum plate 12 Radial drum roller 13a, 13b Main electrode 14 Electrolytic process liquid 15 Electrolyte supply port 16 Slit 17 Electrolyte passage 18 Auxiliary anode 19a, 19b Thyristor 20 AC power source 21 Main electrolytic cell 22 Auxiliary anode tank

Claims (1)

  The support has two or more positive recording layers that contain a resin and an infrared absorber and increase the solubility in an alkaline aqueous solution by infrared laser exposure, and is closest to the support among the positive recording layers A lithographic printing plate precursor, wherein the positive recording layer contains a water-insoluble and alkali-soluble resin and an onium salt.

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