JP2009090645A - Original printing plate of lithographic printing plate and method for printing using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-machine developing type original printing plate of a lithographic printing plate capable of performing printing without passing through a developing processing process after exposure, and obtaining good initial inking properties and stain resistance by keeping a sufficient printing wear, and to provide a method for printing using it. <P>SOLUTION: The original printing plate of the lithographic printing plate is characterized in that the original printing plate of the lithographic printing plate has an image recording layer and a protective layer in this order on a substrate, and an ammonium salt expressed by general formula (I) to general formula (III) is incorporated in the image recording layer and/or the protective layer. In these formulae, R<SP>1</SP>-R<SP>3</SP>and R<SP>5</SP>are respectively independently an alkyl group or the like, R<SP>4</SP>and R<SP>6</SP>are each an n-valent organic residue, W is an organic connecting group, and X<SP>-</SP>is an anion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a planographic printing plate precursor and a printing method using the same. Specifically, the present invention relates to a lithographic printing plate precursor capable of image recording with a laser and capable of on-press development, and a printing method using the same.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). As described above, a difference in ink adhesion is caused on the surface of a lithographic printing plate, and after ink is applied only to an image portion, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Usually, after exposing the lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer corresponding to the image portion remains, and the unnecessary image recording layer corresponding to the non-image portion is removed with an alkaline developer. Alternatively, the lithographic printing plate is obtained by dissolving and removing with an organic solvent-containing developer and exposing the surface of the hydrophilic support to form a non-image area.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing an unnecessary image recording layer with a developer or the like is required after exposure. However, such additional wet processing is unnecessary or Simplification is cited as one of the issues. In particular, in recent years, disposal of waste liquids discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and therefore, the demand for solving the above-mentioned problems has become stronger.

On the other hand, as one simple plate making method, an image recording layer that can remove unnecessary portions of the image recording layer in a normal printing process is used. A method called on-press development has been proposed in which unnecessary portions are removed to obtain a lithographic printing plate.
As a specific method of on-press development, for example, a method using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in a dampening water, an ink solvent, or an emulsion of a dampening water and an ink. , Method of mechanically removing the image recording layer by contact with rollers or blankets of a printing press, cohesion of the image recording layer or adhesion between the image recording layer and the support by penetration of dampening water, ink solvent, etc. There is a method in which after the force is weakened, the image recording layer is mechanically removed by contact with rollers or a blanket.
In the present invention, unless otherwise specified, the “development process step” refers to using a device other than a printing press (usually an automatic developing machine) and bringing a liquid (usually an alkaline developer) into contact therewith. Refers to the process of removing the image recording layer of the unexposed portion of the lithographic printing plate precursor and exposing the surface of the hydrophilic support, and “on-press development” refers to a liquid (usually printing ink) using a printing press. And / or dampening water) to remove the image recording layer of the unexposed portion of the lithographic printing plate precursor and to expose the surface of the hydrophilic support.

  On the other hand, in recent years, digitization technology for electronically processing, storing, and outputting image information by a computer has become widespread, and various new image output methods corresponding to such digitization technology will be put into practical use. It is becoming. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate technology for manufacturing is attracting attention. Therefore, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.

In the above-described simplification, drying, or no processing of the plate-making work, the image recording layer after exposure is not fixed by the development processing, and thus has photosensitivity and may be covered before printing. Therefore, an image recording layer and a light source that can be handled in a bright room or under a yellow light are required.
As such a laser light source, a solid-state laser such as a semiconductor laser and a YAG laser that emits infrared light having a wavelength of 760 to 1200 nm is extremely useful because a high-power and small-sized laser can be obtained at low cost. . A UV laser can also be used.

As an on-press development type lithographic printing plate precursor for image recording with an infrared laser, for example, an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is provided on a hydrophilic support. A planographic printing plate precursor is described (for example, see Patent Document 1). This lithographic printing plate precursor is exposed by an infrared laser to form an image by coalescence of hydrophobic thermoplastic polymer particles by heat. After exposure, the lithographic printing plate precursor is mounted on a cylinder of a printing machine, It describes that it can be developed on-press with ink.
As described above, the image portion obtained by the method of forming an image by mere thermal fusion of the fine particles has extremely low strength, that is, adhesion between the support and the image portion, and has insufficient printing durability. Had the problem.

  Further, as a lithographic printing plate suitable for other on-press development, a lithographic printing plate precursor containing a microcapsule containing a polymerizable compound on a hydrophilic support (see, for example, Patent Documents 2 and 3) or a support. A planographic printing plate precursor (see, for example, Patent Document 4) in which a photosensitive layer (image recording layer) containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on the body has been proposed.

The method of forming an image by these polymerization reactions has a feature that the image strength is relatively good because the chemical bond density of the image portion is higher than that of the image portion formed by thermal fusion of polymer fine particles. In order to prevent polymerization inhibition due to oxygen in the air and adhesion of the back surface due to stickiness of the polymerizable compound, it was necessary to provide an oxygen-blocking protective layer (overcoat layer) on the photosensitive layer.
As a protective layer used for this purpose, it is generally known that a water-soluble resin such as polyvinyl alcohol is used. Specifically, on-press development type lithographic printing provided with a protective layer using modified polyvinyl alcohol. A lithographic printing plate precursor (see, for example, Patent Document 6) provided with a protective layer using an inorganic layered compound such as mica having an oxygen-blocking ability and a water-soluble resin. Etc. have been proposed.

However, the on-press development type lithographic printing plate precursor has a problem in that initial hydrophilicity at the start of printing is deteriorated by providing these hydrophilic protective layers. In other words, the protective layer is removed at the same time when the conventional lithographic printing plate precursor is made by wet development with an alkaline developer, but the on-press development type has a protective layer at the start of printing. Until the protective layer on the image area is removed, the ink does not deposit due to the high hydrophilicity of the protective layer. This problem of initial inking property is further deteriorated when an inorganic layered compound such as mica is included in the protective layer as in Patent Document 6.
For such problems, it has been proposed to add an onium salt to the protective layer for the purpose of improving the wearability (see, for example, Patent Document 7). However, there is a concern that the onium salt precipitates in the protective layer coating solution or the dispersion stability of the inorganic layered compound is lowered, and the inorganic layered compound precipitates when the protective layer coating solution is prepared and then aged. There was a problem. Further, it has been found that even in such a measure, the initial inking property is still insufficient for practical use, and further, stains are likely to occur during printing with a reduced amount of dampening water.

Japanese Patent No. 2938397 JP 2001-277740 A JP 2001-277742 A JP 2005-271284 A JP 2005-119273 A JP 2006-297907 A

  Accordingly, an object of the present invention is to provide an on-press development type lithographic printing plate precursor capable of obtaining good initial inking property and stain resistance while maintaining sufficient printing durability, and a printing method using the same. There is.

As a result of various studies to solve the above problems, the present inventor has found that the above problems can be solved by using an ammonium salt having a specific structure, leading to the present invention.
That is, the present invention is as follows.

1. A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, comprising an ammonium salt represented by the following general formula (I) in the image recording layer and / or protective layer A lithographic printing plate precursor.

In general formula (I), R ¹ , R ² and R ³ each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, an aralkyl group, a heterocyclic group or a hydrogen atom. At least two of R ¹ , R ² and R ³ may combine to form a ring. W represents an n-valent organic linking group, and n represents an integer of 2 to 4. X ⁻ represents an arbitrary anion.

2. A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, comprising an ammonium salt represented by the following general formula (II) in the image recording layer and / or protective layer A lithographic printing plate precursor.

In general formula (II), R ¹ , R ² and R ³ each independently represents an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, aralkyl group, heterocyclic group or hydrogen atom. At least two of R ¹ , R ² and R ³ may combine to form a ring. R ⁴ represents an n-valent organic residue. n represents 2 or 3, and m represents a number satisfying n × m = 2. W represents a divalent organic linking group.

3. A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, comprising an ammonium salt represented by the following general formula (III) in the image recording layer and / or protective layer A lithographic printing plate precursor.

In general formula (III), R ¹ , R ² , R ³ and R ⁵ each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, an aralkyl group, a heterocyclic group or a hydrogen atom. . At least two of R ¹ , R ² , R ³ and R ⁵ may combine to form a ring. R ⁶ represents an n-valent organic residue. n represents 2 or 3.

4). The total carbon number of R ¹ , R ² and R ^{3 in} the general formulas (I) to (II) or the total carbon number of R ¹ , R ² , R ³ and R ^{5 in} the general formula (III) is 8 to 8 The lithographic printing plate precursor as described in any one of 1 to 3 above, which is 20.
5). 5. The lithographic printing according to any one of 1 to 4, wherein at least one of R ^{1 to} R ^{3 in} the general formula (I) to the general formula (III) is an aryl group or an aralkyl group. Version original edition.
6). 4. The lithographic printing plate precursor as described in any one of 1 to 3 above, wherein the protective layer contains an inorganic stratiform compound.

7). 6. The lithographic plate as described in any one of 1 to 5 above, wherein the image recording layer contains (A) an infrared absorber, (B) a radical polymerization initiator, and (C) a polymerizable compound. A printing plate master.
8). The lithographic printing plate precursor as described in any one of 1 to 6 above, wherein the image recording layer contains (A) an infrared absorber and (D) a hydrophobized precursor.
9. 9. The lithographic printing plate precursor as described in any one of 1 to 8 above, wherein the image recording layer contains microcapsules and / or microgels.
10. 1 to 9 above, wherein the image recording layer is an image recording layer capable of forming an image by supplying printing ink and fountain solution on a printing machine after exposure to remove an unexposed portion. The lithographic printing plate precursor as described in any one of the above.
11. The lithographic printing plate precursor as described in 10 above is image-exposed and then mounted on a printing press or image-exposed after being mounted on a printing press, printing ink and fountain solution are supplied to perform on-press development, and printing A printing method characterized by:

  According to the present invention, an on-press development type lithographic plate which can be printed after the exposure without undergoing a development processing step, and can obtain good initial inking property and stain resistance while maintaining sufficient printing durability. A printing plate precursor and a printing method using the same can be provided.

[Lithographic printing plate precursor]
The lithographic printing plate precursor according to the invention has an image recording layer and a protective layer in this order on a support, and the image recording layer and / or protective layer contains an ammonium salt having a specific structure. Further, the image recording layer is particularly preferably an image recording layer capable of forming an image after exposure by supplying printing ink and fountain solution on a printing machine to remove an unexposed portion.
In the planographic printing plate precursor of the present invention, in addition to the image recording layer and the protective layer on the support,
If desired, an arbitrary layer such as an undercoat layer, an intermediate layer, or a backcoat layer can be provided.

(Image recording layer)
First, the image forming aspect of the image recording layer and the constituent components of the image recording layer in the lithographic printing plate precursor according to the invention will be described in detail.
The planographic printing plate precursor of the present invention can be printed by supplying dampening water and printing ink without passing through a development processing step such as a wet development processing step after imagewise exposure. is there. That is, the image recording layer in the lithographic printing plate precursor according to the invention is formed as follows.

  First, the image recording layer becomes a printing ink receiving portion having a hydrophobic (lipophilic) surface by curing the exposed portion. On the other hand, since the image recording layer is in an uncured state in the unexposed area, the hydrophilic surface of the support is removed by dissolution, dispersion, or film removal by contact with dampening water and / or printing ink. Will be exposed. In the lithographic printing plate precursor thus imaged, fountain solution is then selectively attached to the exposed hydrophilic surface of the support, and the printing ink is exposed to the image recording layer (printing ink receiving layer) in the exposed area. And printing is started.

As the image recording layer showing the above image forming mode, the image recording layer contains (A) an infrared absorber, (B) a polymerization initiator, and (C) a polymerizable compound, and an exposed area is polymerized and cured. A polymerization-type image recording layer for forming a film, (A) an infrared absorber, and (D) a hydrophobized precursor, and the hydrophobized precursor is fused to each other in an exposed region to form an image portion. Examples thereof include a hydrophobized precursor curable image recording layer.
Therefore, the image recording layer of the present invention contains the ammonium salt represented by the general formula (I) to the general formula (III) in the polymerization type or hydrophobic precursor curing type image recording layer component. This is a characteristic configuration. The image recording layer can further contain other components as required.
Hereinafter, the constituent components of the image recording layer in the present invention will be sequentially described.

<Ammonium salt represented by formula (I)>

In general formula (I), R < ¹ > -R < ³ > represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, an aralkyl group, a heterocyclic group, or a hydrogen atom each independently. At least two of R ¹ , R ² and R ³ may combine to form a ring. n represents an integer of 2 to 4, and W represents an n-valent organic linking group. X ⁻ represents an arbitrary anion.

When R ^{1 to} R ³ are alkyl groups, examples of the alkyl groups include alkyl groups having 1 to 24 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, Each group such as isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl, n-hexyl, isohexyl, n-heptyl, n-octyl, nonyl, decyl, dodecyl, cetyl, stearyl Can be mentioned.
The alkyl group may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced include a hydroxyl group, an alkyloxy group, an alkylthio group, and a halogen atom.
When R ^{1 to} R ³ are alkenyl groups, examples of the alkenyl groups include alkenyl groups having 1 to 24 carbon atoms.
The alkenyl group may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced include a hydroxyl group, an alkyloxy group, an alkylthio group, and a halogen atom.

When R ^{1 to} R ³ are alkynyl groups, examples of the alkynyl group include alkynyl groups having 1 to 24 carbon atoms.
The alkynyl group may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced include a hydroxyl group, an alkyloxy group, an alkylthio group, and a halogen atom.
When R ^{1 to} R ³ are cycloalkyl groups, examples of the cycloalkyl group include cycloalkyl groups having 3 to 7 carbon atoms. Specific examples include groups such as cyclobutyl, cyclopentyl, and cyclohexyl. Can be mentioned.
The cycloalkyl group may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced include a hydroxyl group, an alkyloxy group, an alkylthio group, and a halogen atom.

When R ^{1 to} R ³ are an aralkyl group, examples of the aralkyl group include aralkyl groups having 1 to 24 carbon atoms, and specific examples include a benzyl group.
The aralkyl group may be unsubstituted or may have a substituent, and examples of the substituent that can be introduced include a hydroxyl group, an alkyloxy group, an alkylthio group, and a halogen atom.

The R ^{1 to} R ³ may be a heterocyclic group.
The heterocyclic group may be unsubstituted or may have a substituent. Examples of the substituent that can be introduced include a hydroxyl group, an alkyloxy group, an alkylthio group, and a halogen atom.
At least two of R ^{1 to} R ³ may be bonded to form a ring.
Preferred examples of R ^{1 to} R ³ include a methyl group, an n-butyl group, an octyl group, a phenyl group, and a benzyl group.

nX ⁻ represents a counter anion, and n represents an integer of 2 or more. Specific examples of X ⁻ include PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , or an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, An organic sulfonate anion having a substituent selected from an aryl group, an aralkyl group and a heterocyclic group.

  The n-valent organic linking group represented by W is a polyvalent organic group composed of non-metallic atoms, from 1 to 60 carbon atoms, from 0 to 10 nitrogen atoms, from 0 Preferred are those composed of up to 50 oxygen atoms, 1 to 100 hydrogen atoms, and 0 to 20 sulfur atoms. More specific examples include organic linking groups constituted by the following structures alone or in combination.

  The organic linking group represented by W may further have a substituent. Examples of the substituent that can be introduced include a halogen atom, a hydroxyl group, a carboxyl group, a sulfonate group, a nitro group, a cyano group, and an amide group. Amino group, alkyl group, alkenyl group, alkynyl group, aryl group, substituted oxy group, substituted sulfonyl group, substituted carbonyl group, substituted sulfinyl group, sulfo group, phosphono group, phosphonato group, silyl group, heterocyclic group, etc. Can be mentioned.

<Ammonium salt represented by formula (II)>

In general formula (II), R ¹ , R ² and R ³ each independently represents an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, aralkyl group, heterocyclic group or hydrogen atom. At least two of R ¹ , R ² and R ³ may combine to form a ring. R ⁴ represents an n-valent organic residue. n represents 2 or 3, and m represents a number satisfying n × m = 2. W represents a divalent organic linking group.

In the general formula (II), R ¹ ~R ³ is the same meaning as R ¹ to R ³ in the general formula (I). Examples of the organic residue represented by R ⁴ include aliphatic hydrocarbon, aromatic hydrocarbon residue and heterocyclic compound residue having 20 or less carbon atoms. Of these, aromatic hydrocarbon residues are preferable, and divalent or trivalent residues of benzene and naphthalene are particularly preferable. Particularly preferred specific examples of the anion moiety containing these residues include 1,5-naphthalenedisulfonate anion, 2,6-naphthalenedisulfonate anion, 2,7-naphthalenedisulfonate anion, 2-naphthol-6,8. -Disulfonate anion, 1,3,6-naphthalene trisulfonate anion, 1
, 3-benzenedisulfonic acid anion. Preferred examples of W are the same as in the case where W in the general formula (I) is a divalent linking group.

<Ammonium salt represented by formula (III)>

In general formula (III), R ¹ to R ³ and R ⁵ each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, an aralkyl group, a heterocyclic group or a hydrogen atom. At least two of R ¹ , R ² and R ³ may combine to form a ring. R ⁶ represents an n-valent organic residue. n represents 2 or 3.

In general formula (III), R < ¹ > -R < ³ > and R < ⁵ > are synonymous with R < ¹ > -R < ³ > of general formula (I). R ⁶
Is synonymous with R ⁴ in the general formula (II), and preferred specific examples of the anion moiety containing the organic residue include the same as those in the general formula (II).

In the ammonium salt used in the present invention, the general formula (I) or formula (II) ^R 1 ~R ³ or the general formula (III) ^R 1 ~R ³ and at least two binding of ^{R 5} in the in A ring may be formed. At this time, those having a heterocyclic structure represented by the following general formulas (IV) to (VII) are particularly preferable.
That is, imidazolinium salts represented by the following general formula (IV), benzimidazolinium salts represented by the following general formula (V), pyridinium salts represented by the following general formula (VI), and the following general formula (VII) Those having the structure of the quinolinium salts shown are preferably used.
Among these, pyridinium salts represented by the general formula (V) are particularly preferable from the viewpoint of inking properties.

In the general formula (IV) to general formula (VII), R ⁷ , R ⁸ and R ⁹ are each independently an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aralkyl group, complex Represents a ring group or a hydrogen atom. R ^{7, R} 8, ^{R 9} has the same meaning as ^R 1 to R ³ in the general formula (I) and formula (II), and preferred examples are also the same.
Y ⁻ in the general formula (IV) to the general formula (VII) has the same meaning as the counter anion in the general formula (I), and preferred examples thereof are also the same.

Among the ammonium salts of the present invention, quaternary ammonium salts and pyridinium salts are preferably used, and quaternary ammonium salts are particularly preferable from the viewpoint of the effect of improving the inking property. Further, among quaternary ammonium salts, those having an aryl group or an aralkyl group, particularly those having an aralkyl group are preferred.
Among these, the most preferable one is a quaternary ammonium salt, in which all substituents directly bonded to the nitrogen atom of ammonium have a total carbon number of 8 to 20, more preferably 9 to 15 and at least one of the substituents is an aryl group or an aralkyl group. In particular, when the total number of carbon atoms of the substituents bonded to the nitrogen atom is in the range of 8 to 20 and at least one of the substituents is a phenyl group or a benzyl group, excellent inking properties are achieved.
As the anion moiety, an aryl group, an aralkyl group, an organic sulfonate anion having a substituent carbon atoms selected from 6 or more alkyl groups, and PF ₆ ^- are preferred, PF ₆ ^- are preferable.

  Specific examples of the ammonium salts that can be used in the present invention [Exemplary compounds (A-1) to (A-54)] are shown below, but the present invention is not limited thereto.

  The amount of ammonium salt added to the image recording layer is preferably 0.1 to 10% by mass, more preferably 0.5 to 7% by mass, and most preferably 1 to 5% by mass in the total solid content of the image recording layer. preferable. In this addition amount range, remaining in the non-image area after on-press development is suppressed, and there is no fear of deterioration of soiling properties, and a particularly excellent effect of improving initial inking property is obtained.

Next, other components contained in the image recording layer according to the present invention will be described.
As described above, preferable image forming mechanisms applicable to the image recording layer of the present invention include (1) an aspect in which an image portion is cured using a polymerization reaction, and (2) thermal fusion of a hydrophobized precursor, An embodiment in which a hydrophobic region (image portion) is formed by utilizing a thermal reaction can be mentioned. Further, (D) a hydrophobized precursor may be contained in the polymerization type image recording layer (1).
Furthermore, various components can be added to these image recording layers according to the purpose.
Hereinafter, each component that can be included in the image recording layer will be sequentially described.

<(A) Infrared absorber>
The lithographic printing plate precursor according to the invention contains (A) an infrared absorber, whereby image formation using an infrared ray such as a laser emitting an infrared ray of 760 to 1200 nm as a light source becomes possible.
The infrared absorber has a function of converting the absorbed infrared rays into heat and a function of being excited by infrared rays and transferring electrons / energy to a polymerization initiator (radical generator) described later. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

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-60-78787, JP-A-58-173696, The methine dyes described in JP-A-58-181690 and JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, and the like, squarylium dyes described in JP-A-58-112792, and the like; And cyanine dyes described in British Patent No. 434,875.

In addition, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also suitable. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59- No. 41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, and Pyrlium compounds described in JP-A-59-216146. And pentamethine thiopyrylium salts described in US Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds shown also preferably used. Another preferable example of the dye includes near infrared absorbing dyes described as the formulas (I) and (II) in US Pat. No. 4,756,993.
In the present invention, other preferred examples of infrared absorbing dyes include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Among these dyes, cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes are preferable. Further, cyanine dyes and indolenine cyanine dyes are preferable, and one particularly preferable example is a cyanine dye represented by the following general formula (i).

In general formula (i), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group represented by the following structural formula. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom including a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows a nitrogen atom, a sulfur atom, an oxygen atom, a halogen atom, and a selenium atom. R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, a substituted amino group and a halogen atom, X _a ^- is Z _a to be described later ^- is the same definition.

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

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Preferred substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, an alkoxy group having 12 or less carbon atoms, a hydrocarbon group having 12 or less carbon atoms, and 12 carbon atoms. Most preferred are not more than alkoxy groups. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include an alkoxy group having 12 or less carbon atoms, a carboxyl group, and a sulfo group, and an alkoxy group having 12 or less carbon atoms is most preferable. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z _a ⁻ represents a counter anion. However, when the cyanine dye represented by formula (i) has an anionic substituent in the structure thereof, Z _a is does not require charge neutralization ^- is not necessary. Preferred Z _a ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably perchloric acid, from the storage stability of the coating solution for the image recording layer. Ions, tetrafluoroborate ions, hexafluorophosphate ions, and aryl sulfonate ions.

Specific examples of cyanine dyes represented by formula (i) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. Can do.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.

  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. Among these pigments, carbon black is preferable.

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

  The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. Within this range, good stability of the pigment dispersion in the coating solution for the image recording layer and good uniformity of the image recording layer can be obtained.

  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).

These infrared absorbers may be added to the same layer as other components, or may be added to another image recording layer provided. However, when a lithographic printing plate precursor is prepared, image recording is performed. The layer is added so that the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm is in the range of 0.3 to 1.2 by the reflection measurement method. Preferably, it is the range of 0.4-1.1. Within this range, a uniform polymerization reaction proceeds in the depth direction of the image recording layer, and good film strength of the image area and adhesion to the support can be obtained.
The absorbance of the image recording layer can be adjusted by the amount of infrared absorber added to the image recording layer and the thickness of the image recording layer. Absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, an image recording layer having a thickness appropriately determined in a range in which the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is set to the optical density. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.

  If the content of the (A) infrared absorber in the image recording layer in the present invention is described in terms of a specific addition amount, 0.1 to 10.0% by mass of the total solid content of the image recording layer is preferable, and more preferable. Is 0.5-5.0 mass%.

<(B) Polymerization initiator>
The (B) polymerization initiator used in the present invention is a compound that generates radicals by light, heat, or both, and initiates and accelerates polymerization of the polymerizable compound (C). As the polymerization initiator that can be used in the present invention, a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, and the like can be used.
Examples of the polymerization initiator in the present invention include (a) an organic halide, (b) a carbonyl compound, (c) an azo polymerization initiator, (d) an organic peroxide, (e) a metallocene compound, (f) Azide compounds, (g) hexaarylbiimidazole compounds, (h) organoborate compounds, (i) disulfone compounds, (j) oxime ester compounds, (k) onium salt compounds.

  (A) Specific examples of organic halides include Wakabayashi et al., “Bull Chem. Soc Japan” 42, 2924 (1969), US Pat. No. 3,905,815, Japanese Patent Publication No. 46-4605, JP-A 48-36281, JP-A 55-32070, JP-A 60-239736, JP-A 61-169835, JP-A 61-169837, JP-A 62-58241, JP Sho 62-212401, JP-A 63-70243, JP-A 63-298339, M.S. P. Examples include compounds described in Hutt “Journal of Heterocyclic Chemistry” 1 (No 3), (1970) ”, and particularly preferable examples include oxazole compounds substituted with a trihalomethyl group and s-triazine compounds.

  More preferred are s-triazine derivatives and oxadiazole derivatives to which at least one mono, di, or trihalogen-substituted methyl group is bonded. Specifically, for example, 2,4,6-tris (monochloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6 -Bis (trichloromethyl) -s-triazine, 2- (3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6- (Trichloromethyl) -s-triazine, 2- (p-bromophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-fluorophenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-trifluoromethylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-dichlorophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (2,6-difluorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-dibromophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (4-biphenylyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4'-chloro-4-biphenylyl) -4,6 Bis (trichloromethyl) -s-triazine, 2- (p-cyanophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-acetylphenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-ethoxycarbonylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-phenoxycarbonylphenyl) -4,6-bis (trichloromethyl)- s-triazine, 2- (p-methylsulfonylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-dimethylsulfoniumphenyl) -4,6-bis (trichloromethyl) -s- Triazine tetrafluoroborate,

2- (2,4-difluorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-diethoxyphosphorylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [4- (4-hydroxyphenylcarbonylamino) phenyl] -4,6-bis (trichloromethyl) -s-triazine, 2- [4- (p-methoxyphenyl) -1,3-butadienyl] -4 , 6-Bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl)- s-triazine, 2- (pi-propyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl) -4,6-bi (Trichloromethyl) -s-triazine, 2- (4-methoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenylthio-4,6-bis (trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (dibromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2-methoxy-4,6-bis (tribromomethyl) -s-triazine, 2- (o-methoxystyryl) -5 Trichloromethyl-1,3,4-oxadiazole, 2- (3,4-epoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- [ -Phenyl-2- (4-methoxyphenyl) vinyl] -5-trichloromethyl-1,3,4-oxadiazole, 2- (p-hydroxystyryl) -5-trichloromethyl-1,3,4-oxa Diazole, 2- (3,4-dihydroxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- (pt-butoxystyryl) -5-trichloromethyl-1,3,4 -Oxadiazole and the like.

  (B) Examples of carbonyl compounds include benzophenone, Michler's ketone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-chlorobenzophenone, 4-bromobenzophenone, 2-carboxybenzophenone and other benzophenone derivatives, 2,2- Dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenylketone, α-hydroxy-2-methylphenylpropanone, 1-hydroxy-1-methylethyl- (p-isopropylphenyl) ketone, 1-hydroxy-1- (p-dodecylphenyl) ketone, 2-methyl- (4 ′-(methylthio) phenyl) -2-morpholino-1-propanone, 1,1,1-trichloromethyl- (p-butylphenol) E) Acetophenone derivatives such as ketone, thioxanthone derivatives such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, Examples thereof include benzoic acid ester derivatives such as ethyl p-dimethylaminobenzoate and ethyl p-diethylaminobenzoate.

  (C) As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.

(D) As the organic peroxide, for example, trimethylcyclohexanone peroxide,
Acetylacetone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 2,2-bis (tert-butylperoxide) Oxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydro Peroxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-oxanoyl peroxide, succinic acid peroxide, Benzoyl oxide, 2,4-di Lorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, dimethoxyisopropyl peroxycarbonate, di (3-methyl-3-methoxybutyl) per Oxydicarbonate, tert-butyl peroxyacetate, tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, tert-butyl peroxyoctanoate, tert-butyl peroxylaurate, tersyl carbonate, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4 , 4 ' Tetra - (p-isopropyl cumylperoxycarbonyl) benzophenone, carbonyl di (t-butylperoxy) and carbonyl di (t-hexyl peroxy dihydrogen diphthalate), and the like.

  (E) As metallocene compounds, JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, JP-A-2-4705 Various titanocene compounds described in JP-A-5-83588, such as di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1- , Di-cyclopentadienyl-Ti-bis-2,4-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl Di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,4,5,6-pen Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4,6-trifluoro Phen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3 4,5,6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-difluoro-3- (pyrrol-1-yl) phen-1-yl, Examples thereof include iron-arene complexes described in 304453 and JP-A-1-152109.

(F) Examples of the azide compound include 2,6-bis (4-azidobenzylidene) -4-methylcyclohexanone.
(G) Examples of hexaarylbiimidazole compounds include JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. Various compounds described in the specification, specifically 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o- Bromophenyl)) 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2, 2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5 , 5'-tetraphenylbiimidazole, 2 , 2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5,5′- Examples include tetraphenylbiimidazole and 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole.

  (H) Examples of the organic borate compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188865, JP-A-9-188686, JP-A-9-188710, JP 2000-131837, JP 2002-107916, JP 2764769, JP 2002-116539, and Kunz, Martin “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”. Organoboron salts described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, and organic boron oxosulfonium complexes described in JP-A-6-157563, JP-A-175554, JP-A-6-17555 Organoboron iodonium complex described in JP-A-9-188, organoboron phosphonium complex described in JP-A-9-188710, JP-A-6-34811, JP-A-7-128785, JP-A-7-140589, Specific examples include organoboron transition metal coordination complexes such as Kaihei 7-306527 and JP-A-7-292014.

  (I) Examples of the disulfone compound include compounds described in JP-A Nos. 61-166544 and 2003-328465.

  (J) Examples of the oxime ester compound include J.M. C. S. Perkin II (1979) 1653-1660), J. MoI. C. S. Examples include Perkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, JP-A 2000-66385, and JP-A 2000-80068. Specific examples thereof include compounds represented by the following structural formula.

  (K) Examples of the onium salt compounds include S.I. I. Schlesinger, Photogr. Sci. Eng. 18, 387 (1974), T .; S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055 and 4,069,056, phosphonium salts described in European Patent Nos. 104 and 143, U.S. Pat. Nos. 339,049 and 410,201, 2-150848, JP-A-2-296514, iodonium salts, European Patent Nos. 370,693, 390,214, 233,567, 297,443, and 297,442 U.S. Pat. Nos. 4,933,377, 161,811, 410,201, 339,049, 4,760,013, 4,73 No. 4,444, 2,833,827, German Patent Nos. 2,904,626, 3,604,580, and 3,604,581, the sulfonium salts described in J . V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), and onium salts such as arsonium salts.

In particular, the above oxime ester compounds, diazonium salts, iodonium salts, and sulfonium salts are preferable in terms of reactivity and stability. In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
Preferred onium salts for the present invention are onium salts represented by the following general formulas (RI-I) to (RI-III).

In the formula (RI-I), Ar ¹¹ represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include an alkyl group having 1 to 12 carbon atoms and 1 carbon atom. -12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1-C12 An alkylamino group, a C1-C12 dialkylamino group, a C1-C12 alkylamide group or arylamide group, a carbonyl group, a carboxyl group, a cyano group, a sulfonyl group, a C1-C12 thioalkyl group, A C1-C12 thioaryl group is mentioned. Z ^11- represents a monovalent anion, a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, stability, Perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, and sulfinate ion are preferable from the viewpoint of the visibility of the printout image.

In formula (RI-II), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents have 1 to 12 carbon atoms. Alkyl group, alkenyl group having 1 to 12 carbon atoms, alkynyl group having 1 to 12 carbon atoms, aryl group having 1 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, aryloxy group having 1 to 12 carbon atoms, halogen atom , C 1-12 alkylamino group, C 1-12 dialkylamino group, C 1-12 alkylamide group or arylamide group, carbonyl group, carboxyl group, cyano group, sulfonyl group, carbon number 1 -12 thioalkyl group and C1-C12 thioaryl group are mentioned. Z ^21- represents a monovalent anion, which is a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, Perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoint of the visibility of the printout image.

In formula (RI-III), R ³¹ , R ³² and R ³³ each independently represents an aryl group having 20 or less carbon atoms, an alkyl group, an alkenyl group or an alkynyl group which may have 1 to 6 substituents. In view of reactivity and stability, an aryl group is desirable. Preferred substituents are alkyl groups having 1 to 12 carbon atoms, alkenyl groups having 1 to 12 carbon atoms, alkynyl groups having 1 to 12 carbon atoms, aryl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, Aryloxy group having 1 to 12 carbon atoms, halogen atom, alkylamino group having 1 to 12 carbon atoms, dialkylamino group having 1 to 12 carbon atoms, alkylamide group or arylamide group having 1 to 12 carbon atoms, carbonyl group, carboxyl Group, a cyano group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms. Z ^31- represents a monovalent anion, which is a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion, Perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoint of the visibility of the printout image, and more preferable examples are described in JP-A-2001-343742. Carboxylate ions, particularly preferably the carboxylate ions described in JP-A No. 2002-148790.

  Examples of onium salts that can be suitably used as a polymerization initiator in the present invention will be given below, but the present invention is not limited thereto.

(B) The polymerization initiator is not limited to the above, but in particular, from the viewpoint of reactivity and stability, (a) an organic halide, in particular, a triazine-based initiator included therein, (j) an oxime ester More preferred are the compounds, (k) diazonium salts, iodonium salts and sulfonium salts included in the onium salt compounds. Among these polymerization initiators, from the viewpoint of improving the visibility of the printout image in combination with an infrared absorber, the onium salt is an inorganic anion such as PF ₆ ⁻ or BF ₄ ⁻ as a counter ion. Etc. are preferred. Furthermore, diaryliodonium is preferred as the onium salt because of its excellent color development.

These (B) polymerization initiators may use only 1 type, and may use 2 or more types together.
(B) The polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass with respect to the total solid content constituting the image recording layer. Can be added at a ratio of Within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained.
These (B) polymerization initiators may be added to the same layer as the other components, or another layer may be provided in the image recording layer or adjacent thereto and added thereto.

<(C) Polymerizable compound>
The polymerizable compound (C) that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and has at least one terminal ethylenically unsaturated bond, preferably two or more. It is chosen from the compound which has. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and their (co) polymers.

  Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or Also suitable are substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a tosyloxy group with monofunctional or polyfunctional alcohols, amines or thiols. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.
Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.
Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.
Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include, for example, aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, and JP-A-59-5241. And those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

  A urethane-based addition-polymerizable compound produced by using an addition reaction between an isocyanate and a hydroxyl group is also suitable. Specific examples of such compounds are described in, for example, JP-B-48-41708. Containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (viii) to a polyisocyanate compound having two or more isocyanate groups in the molecule A vinyl urethane compound etc. are mentioned.

^{_{CH 2 = C (R 4)}} COOCH 2 CH (R 5) OH formula (viii)
(However, R ⁴ and R ⁵ each represent H or CH _3. )

  Further, urethane acrylates as described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56-17654 And urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418. Furthermore, addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 are used. Depending on the case, it is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and acrylic acid or methacrylic acid described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-B-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, specific unsaturated compounds described in each gazette, vinylphosphonic acid compounds described in JP-A-2-25493, and the like are also included. Can be mentioned. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable, and further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrene compound, vinyl ether). It is also effective to adjust both sensitivity and strength by using a compound of the type).
In addition, the selection and use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components in the image recording layer (for example, binder polymer, polymerization initiator, colorant, etc.). For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the support or the protective layer described later.

In the present invention, the polymerizable compound (C) is preferably used in the range of 5 to 80% by mass, and more preferably 25 to 75% by mass with respect to the nonvolatile component in the image recording layer.
In addition, the use method of the addition polymerizable compound can arbitrarily select an appropriate structure, blending, and addition amount from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration / coating method such as undercoating or overcoating can be carried out.

<(D) Hydrophobized precursor>
Examples of the hydrophobizing precursor in the present invention include fine particles that can convert the image recording layer to hydrophobic when heat is applied. The fine particles are preferably at least one particle selected from hydrophobic thermoplastic polymer fine particles and heat-reactive polymer fine particles.

As the hydrophobic thermoplastic polymer fine particles used in the image recording layer, Research Disclosure No. 33303, hydrophobic thermoplastic polymer fine particles described in JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250 and European Patent No. 931647 are suitable. Can be cited as
Specific examples of the polymer constituting such polymer fine particles include homopolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, and vinylcarbazole. Mention may be made of polymers or copolymers or mixtures thereof. Among them, more preferred are polystyrene and polymethyl methacrylate.

The average particle size of the hydrophobic thermoplastic polymer fine particles used in the present invention is preferably 0.01 to 2.0 μm.
Examples of the method for synthesizing the hydrophobic thermoplastic polymer fine particles having the above-mentioned particle size that can be used as a hydrophobizing precursor include an emulsion polymerization method and a suspension polymerization method. In addition, these compounds are dissolved in a water-insoluble organic solvent. There is a method (solution dispersion method) in which this is mixed and emulsified with an aqueous solution containing a dispersing agent, and further heated to solidify into fine particles while flying off the organic solvent.

Examples of the heat-reactive polymer fine particles that can be used as a hydrophobizing precursor in the present invention include thermosetting polymer fine particles and polymer fine particles having a heat-reactive group. The change forms a hydrophobic region.
Examples of the thermosetting polymer include a resin having a phenol skeleton, a urea resin (for example, a urea derivative such as urea or methoxymethylated urea formed by resination with an aldehyde such as formaldehyde), a melamine resin (for example, melamine or its Examples thereof include those obtained by resinating derivatives with aldehydes such as formaldehyde), alkyd resins, unsaturated polyester resins, polyurethane resins, and epoxy resins. Among these, resins having a phenol skeleton, melamine resins, urea resins, and epoxy resins are particularly preferable.

  Suitable resins having a phenol skeleton include, for example, phenol resins obtained by resinizing phenol, cresol, etc. with aldehydes such as formaldehyde, hydroxystyrene resins, N- (p-hydroxyphenyl) methacrylamide, and p-hydroxyphenyl methacrylate. Examples thereof include a polymer or copolymer of methacrylamide or acrylamide or methacrylate or acrylate having a phenol skeleton.

The average particle diameter of the thermosetting polymer fine particles used in the present invention is preferably 0.01 to 2.0 μm.
Such thermosetting polymer fine particles can be easily obtained by a known dissolution and dispersion method, but can also be produced in the form of fine particles when the thermosetting polymer is synthesized. The method for producing the thermosetting polymer fine particles is not limited to these, and a known method can be appropriately employed.

  The thermally reactive group in the polymer fine particle having a thermally reactive group used in the present invention may be any functional group that performs a reaction as long as a chemical bond is formed, but is an ethylenically unsaturated group that performs a radical polymerization reaction. Group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.), cationically polymerizable group (for example, vinyl group, vinyloxy group, etc.), isocyanate group that performs addition reaction or its block, epoxy group, vinyloxy group And a functional group having an active hydrogen atom as a reaction partner (for example, an amino group, a hydroxyl group, a carboxyl group, etc.), a carboxyl group for performing a condensation reaction, a hydroxyl group or an amino group as a reaction partner, a ring-opening addition reaction Preferred examples include acid anhydrides and reaction partners such as amino groups or hydroxyl groups. Door can be.

The introduction of these functional groups into the polymer fine particles may be performed at the time of polymerization, or may be performed using a polymer reaction after the polymerization.
When introduced at the time of polymerization, it is preferable to carry out emulsion polymerization or suspension polymerization of the monomer having the above functional group. Specific examples of the monomer having the above functional group include allyl methacrylate, allyl acrylate, vinyl methacrylate, vinyl acrylate, 2- (vinyloxy) ethyl methacrylate, p-vinyloxystyrene, p- {2- (vinyloxy) ethyl} styrene, Block isocyanate with glycidyl methacrylate, glycidyl acrylate, 2-isocyanatoethyl methacrylate or alcohol thereof, block isocyanate with 2-isocyanate ethyl acrylate or alcohol thereof, 2-aminoethyl methacrylate, 2-aminoethyl acrylate, 2- Hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, acrylic acid, methacrylic acid, maleic anhydride, bifunctional acrylate, 2 officers Methacrylate, and the like, but not limited thereto.

  In the present invention, a copolymer of these monomers and a monomer that is copolymerizable with these monomers and does not have a thermally reactive group can also be used. Examples of the copolymer monomer having no heat-reactive group include styrene, alkyl acrylate, alkyl methacrylate, acrylonitrile, vinyl acetate, and the like. It is not limited to.

  Examples of the polymer reaction used when the introduction of the thermally reactive group is carried out after the polymerization include the polymer reaction described in International Publication No. 96/34316 pamphlet.

  Among the polymer fine particles having a heat-reactive group, those in which the polymer fine particles are coalesced by heat are preferable, and those having a hydrophilic surface and being dispersed in water are particularly preferable. The contact angle (water droplets) of the film prepared by applying only polymer fine particles and drying at a temperature lower than the solidification temperature is higher than the contact angle (water droplets) of the film prepared by drying at a temperature higher than the solidification temperature. It is preferable to lower. In order to make the surface of the polymer fine particles hydrophilic in this way, a hydrophilic polymer or oligomer such as polyvinyl alcohol or polyethylene glycol or a hydrophilic low molecular weight compound may be adsorbed on the surface of the polymer fine particles. However, the surface hydrophilization method is not limited to this.

  The solidification temperature of the polymer fine particles having these thermoreactive groups is preferably 70 ° C. or higher, but more preferably 100 ° C. or higher in view of the stability over time. The average particle size of the polymer fine particles is preferably 0.01 to 2.0 μm, more preferably 0.05 to 2.0 μm, and most preferably 0.1 to 1.0 μm. Within this range, good resolution and stability over time can be obtained.

When forming a hydrophobized precursor curable image recording layer, a coating solution containing these (D) hydrophobized precursor, (A) infrared absorber, and further the ammonium salt of the present invention is prepared. What is necessary is just to apply | coat to the surface. The content of the (A) infrared absorber in the image recording layer coating solution is preferably in the range of 0.1 to 10.0% by mass in terms of solid content, and (D) the hydrophobized precursor is From the viewpoint of image formability, the solid content concentration is preferably in the range of 10 to 98% by mass. The content of the ammonium salt is as described above.
The (D) hydrophobized precursor can also be used as an additive in the polymerization type image recording layer. In this case, the content is in the range of 5 to 90% by mass in terms of solid content. It is preferable that the image portion strength can be improved by addition.

<Microcapsule and / or microgel>
The image recording layer in the invention preferably takes an embodiment containing microcapsules and / or microgels from the viewpoint of obtaining good on-press developability. That is, the image recording layer constituent components (A) to (C) and other constituent components described later are included in microcapsules or microgels.
The microcapsules used in the present invention are those in which all or part of the constituent components of the image recording layer are encapsulated in the microcapsules, as described in, for example, JP-A Nos. 2001-277740 and 2001-277742. It is. The constituent components of the image recording layer can also be contained outside the microcapsules. Furthermore, the image recording layer containing microcapsules is preferably a mode in which hydrophobic constituent components are encapsulated in microcapsules and hydrophilic constituent components are contained outside the microcapsules.

On the other hand, in the present invention, the image recording layer may be an embodiment containing crosslinked resin particles, that is, microgel. This microgel is formed in and / or on the surface thereof with the above-mentioned (A) to (
C) A part of component can be contained. In particular, an embodiment in which a reactive microgel is formed by having (C) a polymerizable compound on the surface thereof is particularly preferable from the viewpoint of image forming sensitivity and printing durability.

  As a method for microencapsulating or microgelling the constituent components of the image recording layer, known methods can be applied.

  For example, as a method for producing a microcapsule, US Pat. No. 2,800,547, US Pat. No. 2,800,498, a method using coacervation, US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, 42-446 by the interfacial polymerization method, U.S. Pat. Nos. 3,418,250 and 3,660,304, by precipitation of polymers, and U.S. Pat. No. 3,796,669. Urea-formaldehyde found in US Pat. No. 3,914,511, US Pat. No. 3,914,511, US Pat. No. 3,914,511, US Pat. No. 4,087,376 and US Pat. No. 4,089,802. System or urea formaldehyde-resorcino A method using a wall forming material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as shown in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method using monomer polymerization, spray drying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling method seen in British Patent Nos. 952807 and 967074, etc. However, it is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Moreover, you may introduce | transduce into the microcapsule wall the compound which has crosslinkable functional groups, such as an ethylenically unsaturated bond which can be introduce | transduced into the binder polymer mentioned later.

On the other hand, as a method for preparing the microgel, granulation by interfacial polymerization described in JP-B-38-19574 and JP-A-42-446, as described in JP-A-5-61214, etc. It is possible to utilize granulation by non-aqueous dispersion polymerization. However, it is not limited to these methods.
As the method using the interfacial polymerization, the known microcapsule production method described above can be applied.

  Preferred microgels used in the present invention are those granulated by interfacial polymerization and having three-dimensional crosslinking. From such a viewpoint, the material to be used is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and polyurea and polyurethane are particularly preferable.

  The average particle size of the microcapsules or microgel is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is further more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

<Other ingredients>
The image recording layer in the present invention can contain other components as required.
Hereinafter, other components constituting the image recording layer in the present invention will be described.

(1) Binder polymer In the image recording layer of the present invention, a binder polymer can be used in order to improve the film strength of the image recording layer. As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and polymers having film properties are preferred. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.

The binder polymer may have crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.
Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, wherein the ester or amide residue (R of -COOR or -CONHR) is Mention may be made of polymers having an ethylenically unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{^{bond, - (CH 2) n CR}} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and — (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group, Represents an alkoxy group or an aryloxy group, and R ¹ and R ² or R ³ may combine with each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadienyl. Represents a residue).
Specific examples of the ester residue include —CH ₂ CH═CH ₂ (described in JP-B-7-21633), —CH ₂ CH ₂ O—CH ₂ CH═CH ₂ , —CH ₂ C. _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 -NHCOO-CH 2 CH = CH 2 and - CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

  The binder polymer having crosslinkability, for example, has a free radical (polymerization initiation radical or a growth radical in the polymerization process of the polymerizable compound) added to the crosslinkable functional group, and the polymerization chain of the polymerizable compound is formed directly between the polymers. Through addition polymerization, a cross-link is formed between the polymer molecules and cured. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded together, thereby causing cross-linking between polymer molecules. Forms and cures.

  The content of the crosslinkable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0, per 1 g of the binder polymer. -7.0 mmol, most preferably 2.0-5.5 mmol. Within this range, good sensitivity and good storage stability can be obtained.

Further, from the viewpoint of improving the on-press developability of the image recording layer unexposed portion, the binder polymer preferably has high solubility or dispersibility in ink and / or fountain solution. In order to improve solubility or dispersibility in ink, the binder polymer is preferably oleophilic, and in order to improve solubility or dispersibility in dampening water, the binder polymer is hydrophilic. Is preferred. For this reason, in the present invention, it is also effective to use a lipophilic binder polymer and a hydrophilic binder polymer in combination.

  Examples of the hydrophilic binder polymer include hydroxyl group, carboxyl group, carboxylate group, hydroxyethyl group, polyoxyethyl group, hydroxypropyl group, polyoxypropyl group, amino group, aminoethyl group, aminopropyl group, and ammonium. Preferred examples include those having a hydrophilic group such as a group, an amide group, a carboxymethyl group, a sulfo group, or a phosphoric acid group.

  Specific examples include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, Polymethacrylic acids and their salts, hydroxyethyl methacrylate homopolymers and copolymers, hydroxyethyl acrylate homopolymers and copolymers, hydroxypropyl methacrylate homopolymers and copolymers, hydroxypropyl acrylate homopolymers and copolymers, hydroxybutyl methacrylate homopolymers Polymers and copolymers, homopolymers and copolymers of hydroxybutyl acrylate, polyethylene glycol , Hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide homopolymers and copolymers having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more Methacrylamide homopolymers and polymers, N-methylolacrylamide homopolymers and copolymers, polyvinylpyrrolidone, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, etc. Is mentioned.

  The binder polymer preferably has a mass average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 250,000. More preferred. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  The binder polymer can be obtained by purchasing a commercial product or synthesizing it by a known method.

The content of the binder polymer is 5 to 90% by mass, preferably 5 to 80% by mass, and more preferably 10 to 70% by mass with respect to the total solid content of the image recording layer. Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use (C) polymeric compound and binder polymer in the quantity used as 0.5 / 1-4/1 by mass ratio.

(2) Surfactant A surfactant can be used for the image recording layer in the invention in order to promote on-press developability and improve the coated surface.
Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.

The nonionic surfactant used for this invention is not specifically limited, A conventionally well-known thing can be used. For example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol Fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N N- bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid ester, trialkylamine oxide, polyethylene glycol, copolymers of polyethylene glycol and polypropylene glycol.

  The anionic surfactant used in the present invention is not particularly limited, and conventionally known anionic surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinate esters, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy poly Oxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef oil, fatty acid alkyl esters Sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, polyoxyethylene alcohol Ruphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, styrene / maleic anhydride Examples thereof include partial saponification products of polymers, partial saponification products of olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.

The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.

  Of the above surfactants, the term “polyoxyethylene” can be read as “polyoxyalkylene” such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc. These surfactants can also be used.

More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Moreover, the fluorine-type surfactant described in each gazette of Unexamined-Japanese-Patent No. 62-170950, 62-226143, and 60-168144 is also mentioned suitably.

Surfactant can be used individually or in combination of 2 or more types.
The content of the surfactant is preferably 0.001 to 10% by mass and more preferably 0.01 to 5% by mass with respect to the total solid content of the image recording layer.

(3) Colorant In the image recording layer of the present invention, a dye having a large absorption in the visible light region can be used 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) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc., and JP-A-62-2 And dyes described in No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.
When these colorants are used, it is easy to distinguish between an image area after image formation and a non-image area, so it is preferable to add them.
The amount added is 0.01 to 10% by mass with respect to the total solid content of the image recording layer.

(4) Print-out agent To the image-recording layer according to the invention, a compound that is discolored by an acid or a radical can be added to form a print-out image.
As such a compound, for example, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

  Specific examples include brilliant green, ethyl violet, methyl green, crystal violet, basic fuchsin, methyl violet 2B, quinaldine red, rose bengal, methanyl yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, Congo Fred, Benzopurpurin 4B, α-Naphthyl Red, Nile Blue 2B, Nile Blue A, Methyl Violet, Malachite Green, Parafuchsin, Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Industry Co., Ltd.], Oil Pink # 312 [Made by Orient Chemical Co., Ltd.], Oil Red 5B [Made by Orient Chemical Co., Ltd.], Oil Scarlet # 308 [Orient Gaku Kogyo Co., Ltd.], Oil Red OG [Orient Chemical Co., Ltd.], Oil Red RR [Orient Chemical Co., Ltd.], Oil Green # 502 [Orient Chemical Co., Ltd.], Spiron Red BEH Special [made by Hodogaya Chemical Co., Ltd.], m-cresol purple, cresol red, rhodamine B, rhodamine 6G, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p- Diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4-pN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4- - dyes and p of diethylamino phenyl imino-5-pyrazolone, p ', p "- hexamethyl triamnotriphenylmethane (leuco crystal violet), and a leuco dye such as Pergascript Blue SRB (manufactured by Ciba-Geigy).

In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoylleucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.

  A suitable addition amount of the dye that changes color by an acid or a radical is preferably 0.01 to 10% by mass with respect to the solid content of the image recording layer.

(5) Polymerization inhibitor In the image recording layer in the present invention, a small amount of a thermal polymerization inhibitor is added in order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during the production or storage of the image recording layer. It is preferable to add.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-t- (Butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), and N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the image recording layer.

(6) Higher Fatty Acid Derivatives etc. In order to prevent polymerization inhibition by oxygen, higher fatty acid derivatives such as behenic acid and behenic acid amide are added to the image recording layer in the present invention, and the drying process after coating. May be unevenly distributed on the surface of the image recording layer.
The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass with respect to the total solid content of the image recording layer.

(7) Plasticizer The image recording layer in the invention may contain a plasticizer in order to improve the on-press developability.
Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in.
The plasticizer content is preferably about 30% by mass or less based on the total solid content of the image recording layer.

(8) Inorganic fine particles The image recording layer in the present invention may contain inorganic fine particles in order to improve the cured film strength and the on-press developability.
Suitable inorganic fine particles include, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof. These can be used for strengthening the film, strengthening the interfacial adhesion by surface roughening, and the like.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 μm to 3 μm. Within the above range, it is possible to form a non-image portion having excellent hydrophilicity, which is stably dispersed in the image recording layer, sufficiently retains the film strength of the image recording layer, and hardly causes stains during printing.
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 40% by mass or less, and more preferably 30% by mass or less, based on the total solid content of the image recording layer.

(9) Low Molecular Hydrophilic Compound The image recording layer in the invention may contain a low molecular hydrophilic compound because it improves on-press developability without reducing printing durability.
As the low molecular weight hydrophilic compound, for example, as the water-soluble organic compound, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like glycols and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as alkylsulfonic acid, toluenesulfonic acid and benzenesulfonic acid and salts thereof, alkylsulfamic acid and the like Organic sulfamic acids and their salts, organic sulfuric acids and their salts such as alkyl sulfuric acid and alkyl ether sulfuric acid, organic phosphonic acids and their salts such as phenylphosphonic acid, tartaric acid, sulphate , Citric acid, malic acid, lactic acid, gluconic acid, organic carboxylic acids and salts thereof and amino acids and the like.
Among these, organic sulfonic acids, organic sulfamic acids, and organic sulfates such as sodium and lithium salts of organic sulfuric acid are preferably used.

Specific examples of organic sulfonates include sodium normal butyl sulfonate, sodium isobutyl sulfonate, sodium sec-butyl sulfonate, sodium tert-butyl sulfonate, sodium normal pentyl sulfonate, and sodium 1-ethylpropyl sulfonate. Sodium hexyl sulfonate, sodium 1,2-dimethylpropyl sulfonate, sodium 2-ethylbutyl sulfonate, sodium cyclohexyl sulfonate, sodium normal heptyl sulfonate, sodium normal octyl sulfonate, sodium tert-octyl sulfonate, normal Sodium nonyl sulfonate, sodium allyl sulfonate, sodium 2-methylallyl sulfonate, sodium benzene sulfonate Sodium p-toluenesulfonate, sodium p-hydroxybenzenesulfonate, sodium p-styrenesulfonate, dimethyl-5-sulfonate sodium isophthalate, disodium 1,3-benzenedisulfonate, 1,3,5-benzenetri Trisodium sulfonate, sodium p-chlorobenzenesulfonate, sodium 3,4-dichlorobenzenesulfonate, sodium 1-naphthylsulfonate, sodium 2-naphthylsulfonate, sodium 4-hydroxynaphthylsulfonate, 1,5-naphthyldisulfone Examples thereof include disodium acid, disodium 2,6-naphthyldisulfonate, trisodium 1,3,6-naphthyltrisulfonate, and lithium salt exchangers thereof.

  Specific examples of the organic sulfamate include sodium normal butyl sulfamate, sodium isobutyl sulfamate, sodium tert-butyl sulfamate, sodium normal pentyl sulfamate, sodium 1-ethylpropyl sulfamate, sodium normal hexyl sulfamate, Examples include sodium 1,2-dimethylpropylsulfamate, sodium 2-ethylbutylsulfamate, sodium cyclohexylsulfamate, and lithium salt exchangers thereof.

  These compounds have a small hydrophobic part structure and almost no surface-active action, and are clearly distinguished from the above-mentioned surfactants in which long-chain alkyl sulfonates and long-chain alkyl benzene sulfonates are used favorably. .

  As the organic sulfate, a compound represented by the following general formula (ix) is preferably used.

  In the general formula (ix), R represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, m represents an integer of 1 to 4, and X represents sodium, potassium, or lithium. .

  R is preferably a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, or an aryl group having 20 or less carbon atoms. Can be mentioned. These groups may further have a substituent. In that case, examples of the substituent that can be introduced include linear, branched or cyclic alkyl groups having 1 to 12 carbon atoms, and those having 1 to 12 carbon atoms. Examples include an alkenyl group, an alkynyl group having 1 to 12 carbon atoms, a halogen atom, and an aryl group having 20 or less carbon atoms.

Preferred examples of the compound represented by the general formula (ix) include sodium oxyethylene-2-ethylhexyl ether sulfate, sodium dioxyethylene-2-ethylhexyl ether sulfate, potassium dioxyethylene-2-ethylhexyl ether sulfate, dioxyethylene Ethylene-2-ethylhexyl ether lithium sulfate, sodium trioxyethylene-2-ethylhexyl ether sulfate, sodium tetraoxyethylene-2-ethylhexyl ether sulfate, sodium dioxyethylene hexyl ether sulfate, sodium dioxyethylene octyl ether sulfate, dioxyethylene Examples include sodium lauryl ether sulfate. Of these, the most preferred compounds include sodium dioxyethylene-2-ethylhexyl ether sulfate, potassium dioxyethylene-2-ethylhexyl ether sulfate, and lithium dioxyethylene-2-ethylhexyl ether sulfate.

The amount of these low molecular weight hydrophilic compounds added to the image recording layer is preferably 0.5% by mass or more and 20% by mass or less of the total solid content of the image recording layer. More preferably, they are 1 mass% or more and 10 mass% or less, More preferably, they are 2 mass% or more and 8 mass% or less. In this range, good on-press developability and printing durability can be obtained.
These compounds may be used alone or in combination of two or more.

(10) Fat sensitizing agent In order to improve the inking property, in particular, when an inorganic layered compound is contained in the protective layer described later, a phosphonium compound may be used in the image recording layer in addition to the ammonium of the present invention. it can. The phosphonium compound functions as a surface coating agent (grease sensitizing agent) for the inorganic layered compound, and prevents deterioration of the inking property during printing by the inorganic layered compound.

  Suitable phosphonium compounds include compounds represented by the following general formula (x) described in JP-A-2006-297907 or the following general formula (xi) described in JP-A-2007-50660.

In general formula (x), R _{1 to} R ₄ are each independently an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aryloxy group, alkylthio group which may have a substituent. Represents a group, a heterocyclic group or a hydrogen atom. At least two of R _{1 to} R ₄ may combine to form a ring. X ⁻ represents a counter anion.

In the general formula (xi), Ar _{1 to} Ar ₆ each independently represents an aryl group or a heterocyclic group, L represents a divalent linking group, X represents an n-valent counter anion, and n represents 1 Represents an integer of ˜3, and m represents a number satisfying nx m = 2. Here, as the aryl group, phenyl group, naphthyl group, tolyl group, xylyl group, fluorophenyl group, chlorophenyl group, bromophenyl group, methoxyphenyl group, ethoxyphenyl group, dimethoxyphenyl group, methoxycarbonylphenyl group, dimethylaminophenyl A group and the like are preferable. Examples of the heterocyclic group include a pyridyl group, a quinolyl group, a pyrimidinyl group, a thienyl group, and a furyl group. L represents a divalent linking group. 6-15 are preferable and, as for carbon number in a coupling group, More preferably, it is a C6-C12 coupling group. X ⁻ represents a counter anion, preferably halogen anions such as Cl ⁻ , Br ⁻ and I ⁻ , sulfonate anions, carboxylate anions, sulfate anions, PF ₆ ⁻ , BF ₄ ⁻ , perchlorate anions. Etc. Of these, halogen anions such as Cl ⁻ , Br ⁻ and I ⁻ , sulfonate anions, and carboxylate anions are particularly preferable.

  Specific examples of the phosphonium compound represented by the general formula (x) or (xi) are shown below.

The amount of the phosphonium compound added to the image recording layer is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and most preferably 0.1 to 5% by mass in the solid content of each layer. Within these ranges, good ink fillability can be obtained.
Note that the above-described sensitizing agent can be added not only to the image recording layer but also to a protective layer described later.

<Formation of image recording layer>
The image recording layer in the present invention is formed by preparing or applying a coating solution by dispersing or dissolving the necessary components described above in a solvent, and coating and drying the coating solution.
Solvents used here 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, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like. However, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.

  In the image recording layer of the present invention, a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents are prepared, and coating and drying are repeated a plurality of times to form a multilayered image recording layer. It is also possible.

Moreover, although the image recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the application, it is generally preferably 0.3 to 3.0 g / m ² . Within this range, good sensitivity and good film properties of the image recording layer can be obtained.
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

(Protective layer)
The lithographic printing plate precursor according to the invention includes a protective layer (overcoat layer) on the image recording layer.
In addition to the function of suppressing the image formation inhibition reaction by blocking oxygen, the protective layer also has functions such as preventing scratches in the image recording layer and preventing ablation during high-illuminance laser exposure.
Hereinafter, components constituting the protective layer will be described.

  Usually, the exposure processing of a lithographic printing plate is carried out in the atmosphere. The image forming reaction in the image recording layer caused by the exposure process can be inhibited by low molecular compounds such as oxygen and basic substances present in the atmosphere. The protective layer prevents low molecular compounds such as oxygen and basic substances from entering the image recording layer, and as a result, suppresses image formation inhibition reaction in the air. Therefore, the property desired for the protective layer is to reduce the permeability of low-molecular compounds such as oxygen, and furthermore, the transparency of light used for exposure is good, and the adhesiveness with the image recording layer is excellent. And it can be easily removed in an on-press development process after exposure. The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729.

As a material used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used. Specifically, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, partially saponified product of polyvinyl acetate, ethylene-vinyl alcohol copolymer, water-soluble cellulose derivative, gelatin, Examples thereof include water-soluble polymers such as starch derivatives and gum arabic, and polymers such as polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, and cellophane.
These may be used in combination of two or more as required.

  A relatively useful material among the above materials includes water-soluble polymer compounds having excellent crystallinity. Specifically, water-soluble acrylic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid, gelatin, gum arabic, and the like are suitable. Among these, water can be applied as a solvent, and at the time of printing Polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl imidazole are preferable from the viewpoint that they are easily removed by the fountain solution. Among them, polyvinyl alcohol (PVA) gives the best results for basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol that can be used in the protective layer may be partially substituted with an ester, an ether, and an acetal as long as it contains a substantial amount of an unsubstituted vinyl alcohol unit having the required water solubility. Similarly, a part may contain other copolymerization components. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxyl groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester modification of vinyl alcohol and various organic acids. Polyvinyl alcohol having various degrees of polymerization having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, etc. at the polymer chain end is also preferably used.

Suitable examples of the modified polyvinyl alcohol include compounds having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, manufactured by Kuraray Co., Ltd. PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, L-8, and the like.
Moreover, as modified polyvinyl alcohol, all made by Kuraray Co., Ltd., KL-318, KL-118, KM-618, KM-118, SK-5102 having anion-modified sites, C having a cation-modified site. -318, C-118, CM-318, M-205, M-115 with terminal thiol modification sites, MP-103, MP-203, MP-102, MP-202 with terminal sulfide modification sites, high grade Examples thereof include HL-12E and HL-1203 having an ester-modified site with a fatty acid at the end, and R-1130, R-2105, and R-2130 having other reactive silane-modified sites.

The protective layer preferably contains an inorganic layered compound, that is, a compound that is an inorganic compound, has a layered structure, and has a flat plate shape. By using such an inorganic layered compound in combination, the oxygen barrier property is further enhanced, and the film strength of the protective layer is further improved and scratch resistance is improved, and the matte property is imparted to the specific protective layer. Can do.
As an inorganic layered compound, for example, the following general formula A (B, C) 2-5D ₄ O ₁₀ (OH, F, O) ₂ [where A is Li, K, Na, Ca, Mg, organic cation] Any one of B and C is any one of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.

Among the mica compounds, natural mica includes muscovite, soda mica, phlogopite, biotite, and sericite. Further, as the synthetic mica, non-swelling mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite-based Na or Li hectorite (Na, Li) 1/8 Mg _{2 / 5Li 1/8 (Si 4} O 10) swelling mica _{F 2.} Synthetic smectite is also useful.

Among the mica compounds, fluorine-based swellable mica, which is a synthetic layered compound, is particularly useful. That is, swellable clay minerals such as mica, montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, and metal atom substitution in the lattice is other than It is significantly larger than clay minerals. As a result, the lattice layer has a shortage of positive charges, and in order to compensate for this, organic cations such as Li ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts and sulfonium salts are provided between the layers. Adsorbs cations. These layered compounds swell with water. If shear is applied in this state, it will be easily cleaved to form a stable sol in water. Bentonite and swellable synthetic mica have a strong tendency and are useful in the present invention. In particular, swellable synthetic mica is preferably used from the viewpoint of availability and uniformity of quality.

  The shape of the layered compound is a flat plate, and from the viewpoint of diffusion control, the thinner the better, the larger the plane size as long as it does not hinder the smoothness of the coated surface or the transmittance of actinic rays. . Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

  As for the particle diameter of the layered compound, the average major axis is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. When the particle diameter is smaller than 0.3 μm, the suppression of permeation of oxygen and moisture is insufficient, and the effect cannot be sufficiently exhibited. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

  When the inorganic layered compound particles having such a large aspect ratio are contained in the protective layer, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor does not deteriorate due to changes in humidity, and the storage stability is excellent.

Next, an example of a general dispersion method when a layered compound is used for the protective layer will be described.
First, 5 to 10 parts by mass of the swellable laminar compound mentioned above as a preferred laminar compound is added to 100 parts by mass of water, and the mixture is thoroughly swelled and swollen. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion containing 5 to 10% by mass of the inorganic layered compound dispersed by the above method is highly viscous or gelled, and has very good storage stability.
When preparing a coating solution for a protective layer using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a binder solution.

  It is preferable that content of the inorganic stratiform compound in a protective layer is 5/1-1/100 by mass ratio with respect to the quantity of the binder used for a protective layer. Even when a plurality of kinds of inorganic layered compounds are used in combination, it is preferable that the total amount of these inorganic layered compounds is compatible with the above-described mass ratio.

  As other additives for the protective layer, for example, glycerin, dipropylene glycol, propionamide, cyclohexanediol, sorbitol and the like are added in an amount corresponding to several mass% with respect to the water-soluble or water-insoluble polymer to give flexibility. be able to. Moreover, well-known additives, such as a water-soluble (meth) acrylic polymer and a water-soluble plasticizer, can be added for improving the physical properties of the film.

Further, the protective layer in the present invention is formed by using a coating solution for a protective layer as described later. This coating solution is used for improving the adhesion with the image recording layer and the stability over time of the coating solution. Known additives may be added.
That is, the protective layer coating solution includes an anionic surfactant, a nonionic surfactant, a cationic surfactant, and a fluorosurfactant for improving coating properties, specifically, sodium alkyl sulfate, alkyl sulfonic acid. Anionic surfactants such as sodium; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ether can be added. These surfactants can be added in an amount of 0.1 to 100% by mass with respect to the water-soluble or water-insoluble polymer.

  In order to improve the adhesion to the image area, for example, JP-A-49-70702 and British Patent Application No. 1303578 disclose an acrylic polymer in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesion can be obtained by mixing 20 to 60% by mass of a water-based emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer and the like, and laminating the mixture on an image recording layer. Any of these known techniques can be used in the present invention.

Furthermore, in the present invention, in order to improve the inking property, the protective layer contains the above general formulas (I) to (III).
It is also a preferred embodiment to add an ammonium salt represented by The amount of ammonium salt compound added to the protective layer is preferably in the range of 0.5 to 30% by mass of the total solid content of the protective layer.

  Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (for example, a water-soluble dye) that is excellent in the transparency of infrared rays used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved.

The protective layer is formed by applying and drying a protective layer coating solution prepared by dispersing or dissolving the protective layer component in a solvent on the image recording layer.
The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water.

The method for applying the protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. .
Specifically, for example, when the protective layer is formed, a blade coating method, an air knife coating method, a gravure coating method, a roll coating coating method, a spray coating method, a dip coating method, a bar coating method, or the like is used.

The coating amount of the protective layer of the coating amount after drying is preferably in the range of 0.01 to 10 g / ^{m 2,} more preferably in the range of 0.02 to 3 g / ^{m 2,} and most preferably 0. in the range of 02~1g / ^{m 2.}

(Support)
The support used for the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (eg, 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 or plastic film on which the above-mentioned metal is laminated or deposited.
A preferable support includes a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. 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 preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.

  Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to the roughening treatment of the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like 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, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, 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. Moreover, the transcription | transfer method which transfers an uneven | corrugated shape with the roll which provided the unevenness | corrugation in the rolling stage of aluminum can also be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

  The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

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, hydrochloric 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 conditions of anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / ^{m 2,} and more preferably 1.5 to 4.0 g / ^{m 2.} Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is. However, in order to further improve the adhesiveness with the upper layer, hydrophilicity, dirt resistance, heat insulation and the like. If necessary, it is immersed in an aqueous solution containing a hydrophilic compound and a micropore enlargement treatment or sealing treatment of an anodized film described in JP-A-2001-253181 or JP-A-2001-322365. The surface hydrophilization treatment to be performed can be appropriately selected and performed. Of course, the enlargement process and the sealing process are not limited to those described above, and any conventionally known methods can be performed. For example, as the sealing treatment, in addition to the vapor sealing, a single treatment with fluorinated zirconic acid, a treatment with sodium fluoride, and a vapor sealing with addition of lithium chloride are possible.

  The sealing treatment used in the present invention is not particularly limited, and a conventionally known method can be used. Among them, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and hot water. Sealing treatment is preferred. Each will be described below.

<1> Sealing treatment with an aqueous solution containing an inorganic fluorine compound As the inorganic fluorine compound used for the sealing treatment with an aqueous solution containing an inorganic fluorine compound, a metal fluoride is preferably exemplified.
Specifically, for example, sodium fluoride, potassium fluoride, calcium fluoride, magnesium fluoride, sodium fluoride zirconate, potassium fluoride zirconate, sodium fluoride titanate, potassium fluoride titanate, zircon fluoride Ammonium acid, ammonium fluoride titanate, potassium fluoride titanate, zirconate fluoride, titanate fluoride, hexafluorosilicic acid, nickel fluoride, iron fluoride, phosphor fluoride, ammonium fluoride phosphate It is done. Of these, sodium fluorinated zirconate, sodium fluorinated titanate, fluorinated zirconic acid, and fluorinated titanic acid are preferable.

  The concentration of the inorganic fluorine compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, from the viewpoint of sufficiently sealing the micropores of the anodized film. Further, in terms of stain resistance, it is preferably 1% by mass or less, and more preferably 0.5% by mass or less.

  It is preferable that the aqueous solution containing the inorganic fluorine compound further contains a phosphate compound. When the phosphate compound is contained, the hydrophilicity of the surface of the anodized film is improved, so that the on-press developability and stain resistance can be improved.

Suitable examples of the phosphate compound include phosphates of metals such as alkali metals and alkaline earth metals.
Specifically, for example, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, dihydrogen phosphate Potassium, dipotassium hydrogen phosphate, calcium phosphate, sodium ammonium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, hydrogen phosphate Disodium, lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid, phosphotungstic acid, sodium phosphotungstate, ammonium phosphomolybdate, sodium phosphomolybdate, sodium phosphite , Tripolyphosphate Potassium, and sodium pyrophosphate. Of these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.
The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. Is preferred.

  The concentration of the phosphate compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, from the viewpoint of improving on-press developability and stain resistance. Further, in terms of solubility, it is preferably 20% by mass or less, and more preferably 5% by mass or less.

The ratio of each compound in the aqueous solution is not particularly limited, but the mass ratio of the inorganic fluorine compound and the phosphate compound is preferably 1/200 to 10/1, and preferably 1/30 to 2/1. Is more preferable.
The temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower.
The aqueous solution preferably has a pH of 1 or more, more preferably has a pH of 2 or more, preferably has a pH of 11 or less, and more preferably has a pH of 5 or less.
The method for sealing with an aqueous solution containing an inorganic fluorine compound is not particularly limited, and examples thereof include an immersion method and a spray method. These may be used alone or in combination, or may be used in combination of two or more.
Of these, the dipping method is preferred. When the treatment is performed using the dipping method, the treatment time is preferably 1 second or longer, more preferably 3 seconds or longer, and preferably 100 seconds or shorter, and 20 seconds or shorter. More preferred.

<2> Sealing treatment with water vapor Sealing treatment with water vapor includes, for example, a method in which pressurized or normal pressure water vapor is contacted with the anodized film continuously or discontinuously.
The temperature of the water vapor is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 105 ° C. or lower.
The water vapor pressure is preferably in the range (1.008 × 10 ^{5 to} 1.043 × 10 ⁵ Pa) from (atmospheric pressure−50 mmAq) to (atmospheric pressure + 300 mmAq).
Further, the time for which the water vapor is contacted is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, more preferably 20 seconds or shorter.

<3> Sealing treatment with hot water Examples of the sealing treatment with hot water include a method of immersing an aluminum plate on which an anodized film is formed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and even more preferably 20 seconds or shorter.

  The hydrophilization treatment is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There are alkali metal silicate methods. In this method, the support is subjected to immersion treatment or electrolytic treatment with an aqueous solution such as sodium silicate. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in each specification of No.272.

When using a support having insufficient surface hydrophilicity such as a polyester film as the support in the present invention, it is desirable to apply a hydrophilic layer to make the surface hydrophilic. As the hydrophilic layer, at least one element selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and a transition metal described in JP-A-2001-199175 A hydrophilic layer obtained by coating a coating solution containing a colloid of oxide or hydroxide of the above, or organic hydrophilicity obtained by crosslinking or pseudo-crosslinking an organic hydrophilic polymer described in JP-A-2002-79772 A hydrophilic layer having a hydrophilic matrix, a hydrophilic layer having an inorganic hydrophilic matrix obtained by sol-gel conversion comprising hydrolysis and condensation reactions of polyalkoxysilane, titanate, zirconate or aluminate, or a metal oxide A hydrophilic layer consisting of an inorganic thin film with a surface is preferred. . Among these, a hydrophilic layer formed by applying a coating solution containing a silicon oxide or a hydroxide colloid is preferable.

  Moreover, when using a polyester film etc. as a support body in this invention, it is preferable to provide an antistatic layer in the hydrophilic layer side of a support body, the opposite side, or both sides. In the case where the antistatic layer is provided between the support and the hydrophilic layer, it also contributes to improving the adhesion with the hydrophilic layer. As the antistatic layer, a polymer layer in which metal oxide fine particles or a matting agent are dispersed as described in JP-A-2002-79772 can be used.

  The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance can be obtained.

  The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm.

(Back coat layer)
After surface treatment is performed on the support or after an undercoat layer (described later) is formed, a backcoat layer can be provided on the back surface of the support, if necessary.
Examples of the back coat layer include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organic metal compounds or inorganic metal compounds described in JP-A-6-35174, and the like. Preferable examples include a coating layer made of a metal oxide. Of these, the use of silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ is inexpensive. It is preferable in that it is easily available.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the image recording layer and the support, if necessary.
Since the undercoat layer tends to cause the image recording layer to peel off from the support in the unexposed area, the on-press developability is improved. In addition, in the case of infrared laser exposure, since the undercoat layer functions as a heat insulating layer, the heat generated by exposure does not diffuse to the support and can be used efficiently, so that the sensitivity can be increased. is there.

Specific examples of the undercoat layer compound include a silane coupling agent having an addition polymerizable ethylenic double bond reactive group described in JP-A-10-282679, and JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of gazette publication are mentioned suitably.
As the most preferable undercoat layer compound, a polymer resin having an adsorptive group, a hydrophilic group, and a crosslinkable group can be mentioned. This polymer resin is preferably formed by copolymerization of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group.

The polymer resin for the undercoat layer preferably has an adsorptive group on the surface of the hydrophilic support. The presence / absence of adsorptivity to the surface of the hydrophilic support can be determined, for example, by the following method.
A coating night is prepared by dissolving the test compound in a readily soluble solvent, and the coating night is coated and dried on the support so that the coating amount after drying is 30 mg / m ² . Next, after the support coated with the test compound is sufficiently washed with an easily soluble solvent, the residual amount of the test compound that has not been removed by washing is measured to calculate the adsorbed amount of the support. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, liquid chromatography measurement and the like. The compound having the support adsorptivity is a compound that remains at 1 mg / m ² or more even after the washing treatment as described above.

The adsorptive group on the surface of the hydrophilic support is a substance (for example, metal, metal oxide) or a functional group (for example, hydroxyl group) existing on the surface of the hydrophilic support, and a chemical bond (for example, ionic bond, It is a functional group capable of causing a hydrogen bond, a coordinate bond, and a bond due to intermolecular force. The adsorptive group is preferably an acid group or a cationic group.
The acid group preferably has an acid dissociation constant (pKa) of 7 or less. Examples of the acid group include a phenolic hydroxyl group, a carboxyl group, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ , —COCH _2. COCH ₃ is mentioned. Among them, -OPO ₃ H _2, and _-PO 3 _{H 2} are particularly preferred. These acid groups may be metal salts.
The cationic group is preferably an onium group. Examples of the onium group include an ammonium group, a phosphonium group, an arsonium group, a stibonium group, an oxonium group, a sulfonium group, a selenonium group, a stannonium group, and an iodonium group. Among these, an ammonium group, a phosphonium group, and a sulfonium group are preferable, an ammonium group and a phosphonium group are more preferable, and an ammonium group is most preferable.

  As a particularly preferred example of the monomer having an adsorptive group used when synthesizing a polymer resin suitable as a compound for the undercoat layer, a compound represented by the following general formula (U1) or general formula (U2) can be given. It is done.

In the general formulas (U1) and (U2), R ¹ , R ² , and R ³ are each independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms.
R ¹ , R ² , and R ³ are each independently preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferably, it is most preferably a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom.
Z is a functional group adsorbed on the surface of the hydrophilic support, and the adsorptive functional group is as described above.

In general formula (U1) and (U2), L is a single bond or a bivalent coupling group.
L is a divalent aliphatic group (alkylene group, substituted alkylene group, alkenylene group, substituted alkenylene group, alkynylene group, substituted alkynylene group), divalent aromatic group (arylene group, substituted arylene group), or divalent Or an oxygen atom (—O—)
, Sulfur atom (—S—), imino (—NH—), substituted imino (—NR—, R is an aliphatic group, aromatic group or heterocyclic group), or a combination with carbonyl (—CO—) It is preferable.

The divalent aliphatic group may have a cyclic structure or a branched structure. The number of carbon atoms in the divalent aliphatic group is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10. The divalent aliphatic group is preferably a saturated aliphatic group rather than an unsaturated aliphatic group. Furthermore, the divalent aliphatic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxyl group, an aromatic group, and a heterocyclic group.
The number of carbon atoms of the divalent aromatic group is preferably 6 to 20, more preferably 6 to 15, and most preferably 6 to 10. In addition, the divalent aromatic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxyl group, an aliphatic group, an aromatic group, and a heterocyclic group.
The divalent heterocyclic group preferably has a 5-membered or 6-membered ring as a heterocycle. In addition, another heterocyclic ring, an aliphatic ring, or an aromatic ring may be condensed with the heterocyclic ring. The divalent heterocyclic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxyl group, an oxo group (═O), a thioxo group (═S), and an imino group (═NH). , Substituted imino groups (= N—R, R represents an aliphatic group, aromatic group or heterocyclic group), an aliphatic group, an aromatic group, or a heterocyclic group.

In the present invention, L is preferably a divalent linking group containing a plurality of polyoxyalkylene structures. The polyoxyalkylene structure is more preferably a polyoxyethylene structure. In other words, L preferably contains — (OCH ₂ CH ₂ ) _n — (n is an integer of 2 or more).
In General Formula (U1), X is an oxygen atom (—O—) or imino (—NH—). X is more preferably an oxygen atom.
In general formula (U2), Y is a carbon atom or a nitrogen atom. When Y is a nitrogen atom and L is linked to Y to form a quaternary pyridinium group, Z itself is adsorbable, so Z is not essential, and Z may be a hydrogen atom.

  The example of the typical compound represented by general formula (U1) or general formula (U2) below is shown.

  The polymer resin suitable as the undercoat layer compound preferably has a hydrophilic group. Examples of the hydrophilic group include a hydroxyl group, a carboxyl group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, and a hydroxypropyl group. Preferred examples include a group, a polyoxypropyl group, an amino group, an aminoethyl group, an aminopropyl group, an ammonium group, an amide group, a carboxymethyl group, a sulfo group, and a phosphoric acid group. Of these, a sulfo group exhibiting high hydrophilicity is preferable.

Specific examples of the monomer having a sulfo group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, acrylamide t-butylsulfonic acid, Examples include 2-acrylamido-2-methylpropanesulfonic acid, sodium salt of (3-acryloyloxypropyl) butylsulfonic acid, and amine salt. Among these, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferable from the viewpoint of hydrophilic performance and synthetic handling.
These are suitably used when synthesizing a polymer resin suitable as a compound for the undercoat layer.

The polymer resin for the undercoat layer in the present invention preferably has a crosslinkable group. The crosslinkable group can improve the adhesion with the image area. In order to make the polymer resin for the undercoat layer crosslinkable, a crosslinkable functional group such as an ethylenically unsaturated bond is introduced into the side chain of the polymer, or the polar substituent of the polymer resin is countercharged. Or a compound having an ethylenically unsaturated bond may be introduced by forming a salt structure.

  Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, wherein the ester or amide residue (R of -COOR or -CONHR) is Mention may be made of polymers having an ethylenically unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{^{bond, - (CH 2) n CR}} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and — (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group. Represents an alkoxy group or an aryloxy group, and R ¹ and R ² or R ³ may be bonded to each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadi An enyl residue).
Specific examples of the ester residue include —CH ₂ CH═CH ₂ (described in JP-B-7-21633), —CH ₂ CH ₂ O—CH ₂ CH═CH ₂ , —CH ₂ C. _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 NHCOO-CH 2 CH = CH 2 , and - CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ O—Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ OCO—CH═CH _2. Is mentioned.
As the monomer having a crosslinkable group of the polymer resin for the undercoat layer, an ester or amide of acrylic acid or methacrylic acid having the crosslinkable group is preferable.

  The content of the crosslinkable group in the polymer resin for the undercoat layer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol per 1 g of the polymer resin. Preferably it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol. Within this range, both good sensitivity and dirtiness and good storage stability can be obtained.

The polymer resin for the undercoat layer preferably has a mass average molecular weight of 5000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1000 or more, preferably 2000 to 25. More preferably, it is 10,000. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The polymer resin for the undercoat layer may be any of a random polymer, a block polymer, a graft polymer, etc., but is preferably a random polymer.

The polymer resin for undercoating may be used alone or in combination of two or more.
The undercoat layer coating solution is obtained by dissolving the undercoat polymer resin in an organic solvent (for example, methanol, ethanol, acetone, methyl ethyl ketone, etc.) and / or water.
The undercoat layer coating solution may contain an infrared absorber.
Various known methods can be used as a method of applying the undercoat layer coating solution to the support. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
The coating amount (solid content) of the undercoat layer is preferably from 0.1 to 100 mg / m ² , and more preferably from ¹ to 30 mg / m ² .

[Printing method]
The printing method of the present invention comprises the steps of image exposing the above-described lithographic printing plate precursor of the present invention, and supplying oil-based ink and aqueous component without performing any development treatment on the exposed lithographic printing plate precursor. And a printing process for printing, and an unexposed portion of the planographic printing plate precursor is removed in the course of the printing process. The imagewise exposure may be performed by first mounting the lithographic printing plate precursor on a printing machine, or the exposed lithographic printing plate precursor may be mounted on a printing machine, and then printing using the printing machine. By supplying ink and fountain solution and printing as it is, on-machine development processing at the initial stage of printing, that is, the image recording layer in the unexposed area is removed, and accordingly the hydrophilic support surface is formed. Exposed to become dampening water receiving area and can be printed.
Hereinafter, the printing method of the present invention will be described in detail.

In the present invention, the light source used for image exposure is preferably a laser. Although the laser used for this invention is not specifically limited, The solid laser and semiconductor laser etc. which irradiate infrared rays with a wavelength of 760-1200 nm are mentioned suitably.
Regarding the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is preferably 10 to 300 mJ / cm ² . In the laser, it is preferable to use a multi-beam laser device in order to shorten the exposure time.

  The exposed lithographic printing plate precursor is mounted on a plate cylinder of a printing press. In the case of a printing press equipped with a laser exposure device, image exposure is performed after a lithographic printing plate precursor is mounted on a plate cylinder of the printing press.

  After exposing the lithographic printing plate precursor imagewise with an infrared laser and supplying it with dampening water and printing ink without going through a development process such as a wet development process, the exposed part of the image recording layer The image recording layer cured by exposure forms a printing ink receiving portion having an oleophilic surface. On the other hand, in the unexposed area, the uncured image recording layer is removed by dissolution or dispersion by the supplied dampening water and / or printing ink, and a hydrophilic surface is exposed in that area. As a result, the fountain solution adheres to the exposed hydrophilic surface, and the printing ink is deposited on the image recording layer in the exposed area and printing is started.

Here, dampening water or printing ink may be supplied to the printing plate first, but printing is first performed in order to prevent the dampening water from being contaminated by the removed image recording layer components. It is preferable to supply ink. As the fountain solution and printing ink, normal lithographic fountain solution and printing ink are used.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

[Examples 1 to 27 and Comparative Examples 1 to 5]
1. Production of lithographic printing plate precursors (1) to (24), (30), (32), (33) (1) Production of support (part 1)
In order to remove rolling oil on the surface of an aluminum plate (material JIS A 1050) having a thickness of 0.3 mm, a degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, and then the hair diameter was adjusted to 0.00. The aluminum surface was grained using ^three 3 mm bundle-planted nylon brushes and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed well with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. At this time, the etching amount of the grained surface was about 3 g / m ² .

Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. Went. Ferrite was used for the auxiliary anode. 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 nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Subsequently, nitric acid electrolysis was performed in an aqueous solution of 0.5% by mass of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was an anode. In the same manner as described above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying.
Next, the plate was provided with a direct current anodic oxide film having a current density of 15 A / dm ² and a current density of 15 g / m ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolytic solution, followed by washing with water. It dried and produced the support body (1).
Thereafter, in order to ensure the hydrophilicity of the non-image area, the support (1) was subjected to a silicate treatment at 60 ° C. for 10 seconds using a 2.5 mass% No. 3 sodium silicate aqueous solution. The adhesion amount of Si was 10 mg / m ² . Then, it washed with water and the support body (2) was obtained. The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

(2) Formation of undercoat layer Next, the following undercoat liquid (1) is applied onto the support (2) so that the dry coating amount is 20 mg / m ² , and the undercoat layer used in the following experiments is provided. A support was prepared.

<Coating liquid for undercoat layer (1)>
-Undercoat layer compound (1) having the following structure: 0.18 g
・ Methanol 55.24g
・ Water 6.15g

(3) Formation of image recording layer The image recording layer coating solution (1) having the following composition was bar-coated on the undercoat layer formed as described above, and then oven-dried at 100 ° C for 60 seconds to obtain a dry coating amount. An image recording layer of 1.0 g / m ² was formed.
The image recording layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and microgel solution (1) immediately before coating. The image recording layer coating solution to which the ammonium salt of the present invention was added did not cause a problem of precipitation and precipitation even when it was aged at 20 ° C. for 1 day.

<Photosensitive solution (1)>
-Binder polymer (1) [the following structure] 0.162 g
Infrared absorber (1) [the following structure: component (A)] 0.030 g
-Polymerization initiator (1) [the following structure: (B) component] 0.162g
・ Polymerizable compound [component (C)]
(Aronix M215, manufactured by Toagosei Co., Ltd. 0.385 g
・ Pionine A-20 (Takemoto Yushi Co., Ltd.) 0.055g
Ammonium salt or comparative nitrogen-containing compound [compound described in Table 1] (Amount described in Table 1)
・ Fluorosurfactant (1) [The following structure] 0.008g
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g

<Microgel solution (1)>
Microgel (1) [by the following synthesis method] 2.640 g
・ Distilled water 2.425g

  The structures of the infrared absorber (1), the polymerization initiator (1), the binder polymer (1), and the fluorosurfactant (1) described in the photosensitive solution (1) are shown below.

-Synthesis of microgel (1)-
As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g, And 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the water phase component were mixed and emulsified for 10 minutes at 12,000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 50 ° C. for 3 hours. The microgel solution thus obtained was diluted with distilled water to a solid content concentration of 15% by mass, and this was used as the microgel (1). When the average particle size of the microgel was measured by the light scattering method, the average particle size was 0.2 μm.

  The structures of the comparative nitrogen-containing compounds (H-1) and (H-2) used in the lithographic printing plate precursors (32) and (33) [Comparative Examples 3 and 4] shown in Table 1 are shown below. It is as follows.

(3) Formation of Protective Layer After the protective layer coating solution (1) having the following composition was further bar-coated on the image recording layer, it was oven-dried at 120 ° C. for 60 seconds, and the dry coating amount was 0.15 g / m ^2. The lithographic printing plate precursors (1) to (24) [Examples 1 to 24] and the lithographic printing plate precursors (30), (32), (33) [Comparative Examples 1, 3, 4 ] Was obtained.

<Coating liquid for protective layer (1)>
・ Inorganic layered compound dispersion (1) 1.5 g
-Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd. CKS50, sulfonic acid modification,
Saponification degree 99 mol% or more, polymerization degree 300) 6% by mass aqueous solution 0.55 g
-Polyvinyl alcohol (PVA-405 manufactured by Kuraray Co., Ltd., saponification degree: 81.5 mol%,
Degree of polymerization 500) 6% by weight aqueous solution 0.03 g
・ Nippon Emulsion Co., Ltd. surfactant (Emalex 710) 1 mass% aqueous solution 8.60 g
・ Ion-exchanged water 6.0g

(Preparation of inorganic layered compound dispersion (1))
6.4 g of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co., Ltd.) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed particles was 100 or more.

2. Production of lithographic printing plate precursor (25) A lithographic printing plate in the same manner as the production of lithographic printing plate precursor (1) except that the image recording layer coating solution (1) is changed to the image recording layer coating solution (2) shown below. An original plate (25) [Example 25] was obtained.

<Image recording layer coating solution (2)>
・ Binder polymer (1) [above structure] 0.50 g
Infrared absorber (2) [the following structure: component (A)] 0.05 g
-Polymerization initiator (1) [the above structure: component (B)] 0.20 g
・ Polymerizable compound [component (C)]
(Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 1.00 g
・ Sodium n-heptylsulfonate 0.05 g
Ammonium salt compound [compound described in Table 1] (Amount described in Table 1)
・ Fluorosurfactant (1) [above structure] 0.10 g
・ Methyl ethyl ketone 18.0g

3. Preparation of lithographic printing plate precursors (26) and (27) The following image recording layer coating solution (3) was bar-coated on the above support having an undercoat layer, followed by oven drying at 70 ° C. for 60 seconds, followed by drying. An image recording layer having a coating amount of 0.6 g / m ² was produced.

<Image recording layer coating solution (3)>
・ Polymer fine particles (hydrophobized precursor) aqueous dispersion [component (D)] 33.0 g
Infrared absorber (3) [the following structure: component (A)] 1.0 g
・ Pentaerythritol tetraacrylate 0.5g
Ammonium salt compound [compound described in Table 1] (Amount described in Table 1)
・ 0.15-g disodium 1,5-naphthyl disulfonate
・ Methanol 16.0g

(Production of polymer fine particle (hydrophobized precursor) aqueous dispersion)
A stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser is applied to a 1000 ml four-necked flask, and 350 mL of distilled water is added while deoxygenating by introducing nitrogen gas, and the internal temperature becomes 80 ° C. Until heated. 1.5 g of sodium dodecyl sulfate is added as a dispersant, 0.45 g of ammonium persulfide is added as an initiator, and then a mixture of 45.0 g of glycidyl methacrylate and 45.0 g of styrene is added from the dropping funnel over about 1 hour. It was dripped. After the completion of the dropping, the reaction was continued as it was for 5 hours, and then the unreacted monomer was removed by steam distillation. Thereafter, the mixture was cooled and adjusted to pH 6 with ammonia water, and finally pure water was added so that the nonvolatile content was 15% by mass to obtain an aqueous dispersion of polymer fine particles (hydrophobized precursor). The particle size distribution of the polymer fine particles had a maximum value at a particle size of 60 nm.

  Here, the particle size distribution is obtained by taking an electron micrograph of polymer fine particles, measuring a total of 5000 fine particle sizes on the photograph, and a logarithmic scale between 0 and the maximum value of the obtained particle size measurement values. The frequency of appearance of each particle size was plotted and divided into 50. For non-spherical particles, the particle size of spherical particles having the same particle area as that on the photograph was used as the particle size.

The following protective layer coating solution (2) was bar coated on the image recording layer formed as described above, and then oven-dried at 60 ° C. for 120 seconds to form a protective layer having a dry coating amount of 0.3 g / m ^2. Thus, lithographic printing plate precursors (26) and (27) [Examples 26 and 27] were obtained.

<Protective layer coating solution (2)>
・ Carboxymethylcellulose (mass average molecular weight 20,000) 5.0 g
・ Water 50.0g

4). Preparation of lithographic printing plate precursor (28) The lithographic printing plate precursor (7) was prepared except that the protective layer coating solution (3) in which the inorganic layered compound dispersion (1) was not added in the protective layer coating solution (1) was used. A lithographic printing plate precursor (28) [Example 28] was obtained in the same manner as in the preparation.

5). Preparation of lithographic printing plate precursor (29) Lithographic printing except that the protective layer coating solution (4) obtained by adding 10 mg of an ammonium salt compound [Exemplary Compound (A-19)] to the protective layer coating solution (1) was used. A lithographic printing plate precursor (29) [Example 29] was obtained in the same manner as in the preparation of the plate precursor (30).

6). Preparation of lithographic printing plate precursor (31) Preparation of lithographic printing plate precursor (30) except that the protective layer coating solution (1) was further added with a protective layer coating solution (5) in which 10 mg of H-1 was added. Similarly, a lithographic printing plate precursor (31) [Comparative Example 2] was obtained.

7). Preparation of lithographic printing plate precursor (34) A lithographic printing plate precursor (34) [Comparative Example 5] was obtained in the same manner as the preparation of the lithographic printing plate precursor (30) except that the protective layer was not provided.

8). Evaluation of planographic printing plate precursor (exposure and printing)
The obtained lithographic printing plate precursors (1) to (34) were subjected to an external drum rotation speed of 1000 rpm, a laser output of 70%, and a resolution of 2400 dpi on a Fujifilm Co., Ltd. Luxel PLASETTER T-6000III equipped with an infrared semiconductor laser. Exposed. The exposure image included a solid image and a 50% halftone dot chart of a 20 μm dot FM screen.
The obtained exposed original plate was attached to a plate cylinder of a printing machine LITHRONE 26 manufactured by Komori Corporation without developing. Equality-2 (manufactured by FUJIFILM Corporation) / tap water = 2/98 (volume ratio) dampening water and Values-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.) After dampening water and ink were supplied by the standard automatic printing start method of LITHRONE 26 and developed on the machine, 100 sheets were printed on Tokuhishi Art (76.5 kg) paper at a printing speed of 10,000 sheets per hour.

(8-1) Initial fillability The number of print sheets required for the ink density on the print paper in the exposed area of the image recording layer to reach a specified standard density was measured as the initial fillability. These results are shown in Table 1.

(8-2) Printing durability After the above-described evaluation of initial inking property, printing was further continued. As the number of printed sheets was increased, the image recording layer was gradually worn out, so that the ink density on the printed material decreased. Printing durability was evaluated using the number of printed copies when the value measured by the Gretag densitometer for the 50% halftone dot area ratio of the FM screen in the printed material was 5% lower than the measured value for the 100th printed sheet. . The results are shown in Table 1.

(8-3) Dirtiness The resulting lithographic printing plate precursor was subjected to image exposure using a Trendsetter 3244VX manufactured by Creo equipped with an infrared semiconductor laser under the conditions of an output of 6.4 W, an outer drum rotation speed of 150 rpm, and a resolution of 2400 dpi. The exposure image includes a solid image and a halftone dot gradation chart of a 20 μm dot FM screen. The exposed original plate is attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg, and fountain solution [IF102 (etch solution manufactured by FUJIFILM Corporation) / water = 3/97 (volume ratio)] and TRANS-G (N). Using black ink (manufactured by Dainippon Ink & Chemicals, Inc.) and supplying dampening water and ink, 100 sheets were printed at a printing speed of 6000 sheets per hour.
Thereafter, the water scale of the printing press was squeezed, and the amount of water supply was gradually decreased until entanglement occurred in the net image. The degree of entanglement contamination at this time was evaluated by the following index.

A: Good entanglement and sufficient water / ink balance.
B: Slight entanglement occurs but is an acceptable level.
C: NG level in the state where entanglement occurred and the halftone dot shadow side was crushed.
D: Poor entanglement occurs just by squeezing a little water.

  According to Table 1, when the printing method of the present invention was applied using the planographic printing plate precursor of the present invention, Examples 1 to 23, 28, 29 having a polymerization type image recording layer, and a hydrophobic precursor were included. In any of Examples 26 and 27 having an image recording layer, a lithographic printing plate having good printing durability and stain resistance, excellent initial setting at the start of printing, and good on-press developability. It can be seen that

Claims (11)

A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, comprising an ammonium salt represented by the following general formula (I) in the image recording layer and / or protective layer A lithographic printing plate precursor.

In general formula (I), R ¹ , R ² and R ³ each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, an aralkyl group, a heterocyclic group or a hydrogen atom. At least two of R ¹ , R ² and R ³ may combine to form a ring. W represents an n-valent organic linking group, and n represents an integer of 2 to 4. X ⁻ represents an arbitrary anion. A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, comprising an ammonium salt represented by the following general formula (II) in the image recording layer and / or protective layer A lithographic printing plate precursor.

In general formula (II), R ¹ , R ² and R ³ each independently represents an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, aralkyl group, heterocyclic group or hydrogen atom. At least two of R ¹ , R ² and R ³ may combine to form a ring. R ⁴ represents an n-valent organic residue. n represents 2 or 3, and m represents a number satisfying n × m = 2. W represents a divalent organic linking group. A lithographic printing plate precursor having an image recording layer and a protective layer in this order on a support, comprising an ammonium salt represented by the following general formula (III) in the image recording layer and / or protective layer A lithographic printing plate precursor.

In general formula (III), R ¹ , R ² , R ³ and R ⁵ each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, an aralkyl group, a heterocyclic group or a hydrogen atom. . At least two of R ¹ , R ² , R ³ and R ⁵ may combine to form a ring. R ⁶ represents an n-valent organic residue. n represents 2 or 3. The total carbon number of R ¹ , R ² and R ^{3 in} the general formulas (I) to (II) or the total carbon number of R ¹ , R ² , R ³ and R ^{5 in} the general formula (III) is 8 to 8 The lithographic printing plate precursor as claimed in claim 1, wherein the lithographic printing plate precursor is 20. The lithographic printing plate precursor as claimed in any one of Claims 1 to 4, wherein at least one of R ^{1 to} R ^{3 in} the general formula (I) to the general formula (III) is an aryl group or an aralkyl group. .   6. The lithographic printing plate precursor as claimed in claim 1, wherein the protective layer contains an inorganic stratiform compound.   The lithographic printing plate according to claim 1, wherein the image recording layer contains (A) an infrared absorber, (B) a radical polymerization initiator, and (C) a polymerizable compound. Original edition.   The lithographic printing plate precursor as claimed in claim 1, wherein the image recording layer contains (A) an infrared absorber and (D) a hydrophobized precursor.   The lithographic printing plate precursor as claimed in any one of claims 1 to 8, wherein the image recording layer contains microcapsules and / or microgels.   The image recording layer is an image recording layer capable of forming an image by supplying printing ink and fountain solution on a printing machine after exposure to remove an unexposed portion. A lithographic printing plate precursor as described in any of the above.   The lithographic printing plate precursor according to claim 10 is image-exposed after being exposed to an image after being exposed to an image, or image-exposed after being attached to a printer, and is subjected to on-machine development by supplying printing ink and fountain solution, A printing method characterized by printing.