JP2006106059A - Lithographic printing original plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive lithographic printing original plate for an infrared laser for direct plate making excellent in scuffing resistance, printing durability, and discrimination of a formed image. <P>SOLUTION: The lithographic printing original plate has on a support two or more positive recording layers containing a resin and an infrared absorbent and having solubility in an alkaline aqueous solution increased by infrared laser exposure, wherein a positive recording layer closest to the support among the two or more positive recording layers contains at least two or more resins, at least one of which is an alkali-soluble resin having phenolic hydroxyl groups, part of which have been esterified, and a dispersed phase is formed by the alkali-soluble resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

In recent years, the development of lasers has been remarkable, and in particular, solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared can easily obtain high-power and small-sized ones. These lasers are very useful as an exposure light source for making a plate directly from digital data such as a computer.
The positive type lithographic printing plate precursor for infrared laser has an alkaline aqueous solution-soluble binder resin and an infrared absorbing dye (IR dye) that absorbs light and generates heat as essential components. In the image area), it acts as a dissolution inhibitor that substantially lowers the solubility of the binder resin by interaction with the binder resin. In the exposed area (non-image area), the generated heat causes the IR dye and the binder resin to The interaction weakens and dissolves in an alkaline developer to form a lithographic printing plate.
However, in such a positive lithographic printing plate material for infrared laser, the solubility between the non-exposed area (image area) with respect to the developer and the solubility of the exposed area (non-image area) under various use conditions. However, there is a problem that over-development and poor development easily occur due to fluctuations in use conditions. In addition, even if the surface condition slightly changes due to touching the surface during handling, the unexposed area (image area) dissolves and becomes a scratch mark during development, causing deterioration in printing durability and poor inking properties. There was a problem.

Such a problem originates from the essential difference in the plate making mechanism between the positive lithographic printing plate material for infrared laser and the positive lithographic printing plate material made by UV exposure. That is, in a positive type lithographic printing plate material made by UV exposure, an alkaline aqueous solution-soluble binder resin and an onium salt or a quinonediazide compound are essential components. The onium salt or the quinonediazide compound is a non-exposed portion ( In addition to acting as a dissolution inhibitor by interacting with the binder resin in the image area), the exposed area (non-image area) plays two roles: it decomposes by light to generate acid and acts as a dissolution accelerator. Is.
On the other hand, IR dyes and the like in positive lithographic printing plate materials for infrared lasers only act as dissolution inhibitors for non-exposed areas (image areas), and do not promote dissolution of exposed areas (non-image areas). . Therefore, in the positive lithographic printing plate material for infrared laser, in order to make a difference in solubility between the non-exposed portion and the exposed portion, a binder resin having a high solubility in an alkaline developer must be used in advance. In other words, the state before development becomes unstable.

Various proposals have been made to solve the above problems. For example, there has been proposed a method in which the infrared absorber in the film is unevenly distributed in order to improve image discrimination (see, for example, Patent Document 1). However, the problem of scratch resistance on the surface of the recording layer has not been solved. A lithographic plate provided with a recording layer comprising a lower recording layer containing a sulfonamide-based acrylic resin and an upper recording layer containing a water-insoluble and alkali-soluble resin and a photothermal conversion agent and increasing the solubility in an alkaline aqueous solution upon exposure. A printing plate precursor has been proposed (see, for example, Patent Document 2). In this lithographic printing plate precursor, when the recording layer is removed in the exposed region, the lower recording layer excellent in alkali solubility is exposed, and an undesired residual film is quickly removed by the alkali developer. The effect is that the lower recording layer functions as a heat insulating layer, and the thermal diffusion to the support is effectively suppressed. In addition, a method has been proposed in which a polymer is blended in the lower recording layer to provide chemical resistance (see, for example, Patent Document 3).
However, in order to form these multi-layer structures, it is necessary to select resins having different characteristics as the resins used for both layers, and the problem is that their interactivity decreases, or the development of the lower recording layer There is a concern that undesired dissolution occurs at both ends of the lower recording layer portion in the image portion during development due to the good property, which affects printing durability and image reproducibility. There was still room for improvement to take full advantage of the benefits.
JP 2001-281856 A JP 11-218914 A International Publication No. 01/46318 Pamphlet

An object of the present invention is to solve various problems in the prior art and achieve the following objects.
An object of the present invention is to provide an infrared laser-compatible positive planographic printing plate precursor for direct plate making that is excellent in scratch resistance, printing durability, and discrimination of formed images.

As a result of extensive research, the present inventor has provided a positive recording layer having a multilayer structure, and formed a dispersed phase using a specific modified alkali-soluble resin in the recording layer close to the support. The inventors have found that the problem can be solved and completed the present invention.
That is, the lithographic printing plate precursor of the present invention is a lithographic printing plate comprising a support and a resin and an infrared absorber, and two or more positive recording layers that increase the solubility in an aqueous alkali solution by infrared laser exposure. The original version
Among the two or more positive recording layers, the positive recording layer closest to the support contains at least two resins, at least one of these resins has a phenolic hydroxyl group, and , A part of which is an esterified alkali-soluble resin (hereinafter, appropriately referred to as “specifically modified alkali-soluble resin”), and a dispersed phase is formed by the alkali-soluble resin.
Hereinafter, in this specification, “the positive recording layer closest to the support” is appropriately referred to as “lower recording layer”, and other positive recording layers are appropriately referred to as “upper recording layer”. Called.
The lithographic printing plate precursor of the present invention is not limited to the positive recording layer, as long as the effects of the present invention are not impaired, and other layers as desired, for example, a surface protective layer, an undercoat layer, an intermediate layer, A back coat layer and the like can be provided.

The dispersed phase in the present invention is (1) a method using a combination of two or more incompatible resins, or (2) a method of dispersing a particulate polymer selected from microcapsules and latex in a matrix resin, Or the like. In the present invention, in the method (1), at least one kind is a specific modified alkali-soluble resin, and in the method (2), the granular polymer contains a specific modified alkali-soluble resin. It is essential.
In the present invention, it is preferable to form a dispersed phase using the method (1) from the viewpoint of ease of production. Two or more kinds of resins (including the above-mentioned specific modified alkali-soluble resin) used in forming the dispersed phase may be selected from those that are not compatible with each other, and are uniformly dissolved in the coating solvent. Even if it is a thing, you may select what forms a dispersed phase with the removal of a solvent at the time of formation of a lower recording layer.

  As the size of the dispersed phase in the lower recording layer, it is preferable that the maximum major axis is 0.1 to 0.8 μm and the average major axis is 0.05 to 0.6 μm. The size of the disperse phase is determined by giving a conductivity to the cross section of the lower recording layer obtained by cutting with a microtome or the like, and then taking a picture with a scanning electron microscope (SEM) to show the size of the disperse phase in a circle or ellipse. It can be evaluated by an analysis device.

In the lithographic printing plate precursor according to the present invention, since the image forming mechanism uses a method of utilizing a change in solubility in an alkaline aqueous solution, the resin constituting the positive recording layer is insoluble in water and is alkaline. It is preferable that the resin be soluble in an aqueous solution (hereinafter, simply referred to as “alkali-soluble resin”).
In particular, in the lower recording layer, the resin that forms the matrix phase is composed of a water-insoluble / alkali-soluble resin, and the dispersed phase contains a compound that generates an acid or a radical upon irradiation with an infrared laser, or Of the resins, the one that forms a matrix phase is preferably a water-insoluble / alkali-soluble resin, and the dispersed phase preferably contains a compound whose alkali-solubility changes upon irradiation with an infrared laser.

  From the above, in the present invention, a dispersed phase in which solubility in an alkaline aqueous solution is increased by heat or light is formed in the matrix phase of the lower recording layer. In the lower recording layer, the alkali solubility of the dispersed phase is increased in the exposed area (non-image area), and a permeable path of an alkaline aqueous solution (alkaline developer) is formed in the matrix phase. Dissolution of the matrix phase is promoted. In the unexposed area (image area), since the dispersed phase itself has low solubility in an alkaline aqueous solution, the penetration of the alkaline developer into the matrix phase of the lower recording layer, particularly the penetration from the side, is effectively suppressed. Thus, damage caused by the alkaline developer in the image area can be suppressed. Thereby, since the strength of the image portion does not decrease, it is possible to form a sharp image having excellent scratch resistance and printing durability and excellent image discrimination. This characteristic is particularly noticeable in a high-definition image having a small image area. Therefore, the lithographic printing plate precursor according to the present invention is particularly suitable for a high-definition image such as an FM screen which has been used with the recent CTP. Therefore, commercially available FM screens such as Staccato (trade name: manufactured by Creo), FAIRDOT, Randot (trade name: manufactured by Dainippon Screen), Co-Re screen (trade name: manufactured by Fuji Photo Film) For example, it can be suitably used for image formation.

  In the present invention, the dispersed phase in the lower recording layer is formed of a specific modified alkali-soluble resin, and in the dispersed layer, the interaction between the resins due to the ester bond site of the specific modified alkali-soluble resin. Since the property is enhanced, the film strength can be improved. For this reason, since it becomes possible to suppress penetration of dampening water into the lower recording layer during printing, it is estimated that the printing durability can be further improved.

  ADVANTAGE OF THE INVENTION According to this invention, the positive type lithographic printing plate precursor for infrared lasers for direct plate-making excellent in scratch resistance, printing durability, and the discrimination of the formed image can be provided. Therefore, according to the present invention, it is possible to improve the plate-making stability particularly in a high-definition image. Note that the high-definition image includes FM screen images that are increasingly used with the recent CTP conversion.

Hereinafter, the present invention will be described in detail.
The lithographic printing plate precursor of the present invention is a lithographic printing plate precursor comprising a support and a resin and an infrared absorber, and two or more positive recording layers that increase the solubility in an aqueous alkali solution by infrared laser exposure. There,
Among the two or more positive recording layers, the positive recording layer closest to the support contains at least two resins, at least one of these resins has a phenolic hydroxyl group, and A part thereof is an esterified alkali-soluble resin, and a dispersed phase is formed by the alkali-soluble resin.

(Positive recording layer)
A feature of the present invention is that the lower recording layer in the positive recording layer is provided with a dispersed phase made of an alkali-soluble resin (specifically modified alkali-soluble resin) having a phenolic hydroxyl group and partially esterified. There is.
Such a dispersed phase can be formed by the following two modes. (1) A mode in which a matrix phase (that is, a dispersion medium) and a dispersed phase are formed using two or more kinds of incompatible resins. In this case, a specific modified alkali is used as a material constituting the dispersed phase. A dispersion medium is formed from a material that is incompatible with the soluble resin. In another embodiment, (2) after forming a dispersed phase with a specific modified novolak resin in advance using microcapsules or latex, the dispersed phase is introduced into the resin matrix phase. In the dispersed phase, a dissolution inhibitor and an infrared absorber can be added as necessary.

First, the lower recording layer on which the dispersed phase obtained by the method (1) is formed will be described. Here, in the method (1), resins that are not compatible with each other are used. However, if the resins are not compatible with each other, the combination of two or more resins does not form a single-phase solid or liquid in appearance. This means that it can be confirmed by appropriately processing the cross section of the positive recording layer and taking and observing the cross-sectional photograph with a visual or scanning electron microscope.
Below, specific modified alkali-soluble resin is demonstrated.

[Specifically modified alkali-soluble resin]
Examples of the alkali-soluble resin having a phenolic hydroxyl group constituting the specific modified alkali-soluble resin in the present invention include novolak resins, resole resins, polyvinylphenol resins, copolymers of acrylic acid derivatives having phenolic hydroxyl groups, and the like. Among these, novolak resins, resol resins, and polyvinylphenol resins are preferable. The ester portion of the specific modified alkali-soluble resin is preferably made of a sulfonic acid compound or a carboxylic acid compound.

Among these, the specific modified alkali-soluble resin is preferably an ester compound of a polycondensation resin of phenols and aldehydes or ketones and a carboxylic acid compound or a sulfonic acid compound.
Examples of the phenols include monohydric phenols such as phenol, o-cresol, m-cresol, p-cresol, 3,5-xylenol, carvacrol and thymol, dihydric phenols such as catechol, resorcin and hydroquinone, and pyrogallol. And trihydric phenols such as phloroglucin.
Examples of the aldehyde include formaldehyde, benzaldehyde, acetaldehyde, crotonaldehyde, furfural and the like. Of these, preferred are formaldehyde and benzaldehyde.
Examples of the ketone include acetone and methyl ethyl ketone.

Specific examples of polycondensation resins obtained from these materials include phenol / formaldehyde resins, m-cresol / formaldehyde resins, m- and p-mixed cresol / formaldehyde resins, resorcin / formaldehyde resins, resorcin / benzaldehyde resins. And pyrogallol / acetone resin.
The weight average molecular weight of these alkali-soluble resins having a phenolic hydroxyl group is usually in the range of 1,000 to 50,000, preferably in the range of 1,500 to 20,000, and more preferably 2,000. The range is from 10,000 to 10,000.
Moreover, the esterification rate (reaction rate of a sulfonic acid compound or a carboxylic acid compound described later with respect to one OH group) with respect to the phenolic hydroxyl group of the alkali-soluble resin having a phenolic hydroxyl group is preferably in the range of 1 to 40%. A range of 3 to 35% is more preferable, and a range of 15 to 35% is particularly preferable.

As the sulfonic acid compound or carboxylic acid compound used for esterification of the alkali-soluble resin having a phenolic hydroxyl group, an alkylsulfonic acid compound or alkylcarboxylic acid having 1 to 15 carbon atoms which may have a substituent. A compound, an arylsulfonic acid compound having 5 to 20 carbon atoms or an arylcarboxylic acid compound which may have a substituent, a quinonesulfonic acid compound or a quinonecarboxylic acid compound which may have a substituent, and a substituent. Examples thereof include a heterocyclic sulfonic acid compound having 4 to 20 carbon atoms or a heterocyclic carboxylic acid compound. More preferably, as a substituent, an alkyl group, a carboxylic acid group, a hydroxyl group, a primary amino group, a secondary amino group, or a tertiary amino group optionally having 1 to 3 nuclear aryl sulfonic acids in its structure Examples thereof include a compound or an arylcarboxylic acid compound, a 1 to 3 nucleus quinonesulfonic acid compound, or a quinonecarboxylic acid compound.
In particular, the aryl sulfonic acid compound having 1 or 2 nuclei and the quinone sulfonic acid compound having 2 or 3 nuclei which may have a substituent as described above are effective in improving printing durability, scratch resistance, and chemical resistance. This is advantageous.

Here, as described above, a sulfonic acid ester group (R—SO ₃ —) suitable as an ester group constituting the specific modified alkali-soluble resin will be described. In addition, R is represented by the following general formulas QP ^{1 to} QP ⁴ .

(In the general formulas QP ^{1 to} QP ⁴ , X ¹ represents a hydrogen atom or an alkyl group, X ² represents a hydrogen atom or a hydroxyl group, and X ³ represents a structure shown below or —N═N—Y ^3. X ⁴ represents a hydrogen atom or an alkyl group.

Y ¹ and Y ² are each independently a hydrogen atom, alkyl group, aryl group, chlorine atom, bromine atom, iodine atom, fluorine atom, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryl An oxycarbonyl group, an allyloxycarbonyl group, a carboxylic acid group, or a cyano group, but at least one of them is an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an allyloxycarbonyl group, a carboxylic acid group, or a cyano group. Represents a selected group.
Y ³ represents an aryl group which may have a substituent, an alkyl group which may have a substituent, a heterocyclic group which may have a substituent, an alkenyl group, or a substituent. It represents an optionally substituted acyl group or an optionally substituted alkoxycarbonyl group.

  Carbon number of said alkyl group is 1-15, Preferably it is 1-6, Carbon number of an aryl group is 6-20, Preferably it is 6-12, Carbon number of a heterocyclic group is 4-20, Preferably Is 4 to 10, the carbon number of the alkenyl group is 2 to 10, preferably 2 to 6, the carbon number of the acyl group is 2 to 15, preferably 2 to 10, and the carbon number of the alkoxycarbonyl group is 2-15, preferably 2-10.

The aromatic sulfonic acid ester group described above has a hydrophilic group introduced on the aromatic ring in order to suppress stains on non-image areas during printing in addition to printing durability, scratch resistance, and chemical resistance. It is preferable that Examples of the hydrophilic group include a hydroxyl group, a primary amino group, a secondary amino group, a tertiary amino group, a carboxylic acid, and the like. Among them, it is preferable that a hydroxyl group is introduced on the aromatic ring. More preferably, a hydroxyl group and an amino group are introduced on the ring.
As the aromatic sulfonic acid ester group in which a hydrophilic group is introduced on the aromatic ring in this manner, those in which R in the sulfonic acid ester group (R—SO ₃ —) has the following structure are most preferable.

(In the above structure, Z ¹ and Z ² are each independently a hydrogen atom, alkyl group, aryl group, chlorine atom, bromine atom, iodine atom, fluorine atom, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group. , An aryloxycarbonyl group, an allyloxycarbonyl group, a carboxylic acid group, and a cyano group, at least one of which is an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an allyloxycarbonyl group, a carboxylic acid group, or a cyano group. Represents the selected group.)

In order to obtain a specific modified alkali-soluble resin having an aromatic sulfonic acid ester group having a hydrophilic group introduced on the aromatic ring as described above, the following method is preferably used.
That is, an ester compound of an alkali-soluble resin having a phenolic hydroxyl group and a conventionally known o-quinone azidosulfonic acid such as 1,2-benzoquinonediazidesulfonic acid is generated from the viewpoint of ease of synthesis and production cost. Then, a method of modifying the o-quinonediazide group portion of the ester compound is advantageous.
Such modification of the o-quinonediazide group portion is carried out by subjecting the o-quinonediazide group to a known coupling reaction or denitrogenation reaction.

  As a means for modifying the o-quinonediazide group portion of the ester compound, Saul Patal, “The Chemistry of Diazium and diazo groups Partl”, 1978, John Wiley & Sons, published by Saul Patz, edited by Saul Pathl, Sons Patal. ", 1978, John Wiley & Sons Publishing, Viadimir V. Ershov et al. Editing “Quinone Diazides”, 1981, Elsevier Scientific Publishing Company, W.C. Ried and M.M. Butz, Liebigs Ann. Chem. , 716, 190 (1968); Ried and A.M. Keemann, Liebigs Ann. Chem. 689, 145 (1965), E.I. Bamberger, Marie Baum and Leo Schlein, J. Am. Prakt. Chem. 266 (1923), E.E. Bamberger, and S.B. Wildi, J .; Prakt. Chem. 278 (1923), etc., can be used. As a specific example of the reaction for modifying the o-quinonediazide group portion, a reaction using various acids, alkalis, metal catalysts and the like described in JP-A No. 11-288089 can be used.

Hereinafter, although the specific example of the specific modified | denatured alkali-soluble resin in this invention is shown, it is not limited to this.
Compound (Mw3000) in which a part of phenolic hydroxyl group of polycondensed novolak resin of m-cresol and formaldehyde is substituted with W ¹ (reaction rate 30%);
Polycondensation novolak resin of phenol and formaldehyde Compound (Mw2000) in which a part of phenolic hydroxyl group is substituted with W ¹ (reaction rate 30%);
Polycondensed novolak resin of m-resorcin and formaldehyde Compound (Mw3000) in which a part of phenolic hydroxyl group is substituted with W ¹ (reaction rate 20%);
A compound having the structure:

Here, examples of the ester group W ¹ in the above structure include the following.

The structure of W ² in the ester group W ¹ is shown below.

  An o-quinonediazide group moiety in an ester compound of an alkali-soluble resin having a phenolic hydroxyl group and o-quinone azidosulfonic acid is a compound having an active hydrogen represented by the following general formula (A) or general formula (B) (for example, , Compounds obtained by coupling reaction with non-aromatic couplers listed below;

(In the general formula (A), R ^{A1 to} R ^A3 are each independently an alkyl group, a hydrogen atom, an aryl group, a chlorine atom, a bromine atom, an iodine atom, a fluorine atom, an alkoxy group, an aryloxy group, or an acyl group. , An alkoxycarbonyl group, an aryloxycarbonyl group, an allyloxycarbonyl group, a carboxylic acid group, and a cyano group, and at least one of R ^{A1 to} R ^A3 is an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an allyl group Represents a group selected from an oxycarbonyl group, a carboxylic acid group, and a cyano group.)

(In the general formula (B), R ^A1 and R ^A3 have the same meanings as R ^A1 and R ^A3 in the general formula (A). Further, R ^A5 is R ^A3 represents in formula (A) And an amino group which may have a substituent.

  Specific examples of the compound having active hydrogen represented by the general formula (A) and the compound having active hydrogen represented by the general formula (B) are shown below.

  For the o-quinonediazide group part in the ester compound of an alkali-soluble resin having a phenolic hydroxyl group and o-quinone azidosulfonic acid, see Dye Handbook (Organization of Synthetic Organic Chemistry, 1959, published by Maruzen Co., Ltd.), “ORGAMC INTERMEDIATEDS”. ”, (Daito Chemical Industry Co., Ltd., catalog) etc. have at least a hydroxyl group or a nitro group, and may further have a substituent, a 1-3-nuclear aryl compound (for example, listed below) Compound obtained by coupling reaction with an aromatic coupler);

Obtained by inducing a denitrogenation reaction of an o-quinonediazide group portion in an ester compound of an alkali-soluble resin having a phenolic hydroxyl group and o-quinone azidosulfonic acid together with a compound having a hydroxyl group such as an alcohol in the presence of an acid or an alkali. A compound having a hydroxyl group or an alkoxy group as a substituent (denitrogenation reaction product);
Furthermore, the compound which has a structure shown below is mentioned.

  Here, examples of the ester groups XW and XV in the above structure include those shown below.

  The weight average molecular weight of the specific modified alkali-soluble resin in the present invention is in the range of 500 to 20000 from the viewpoints of the formation of a dispersed phase, printing durability, scratch resistance, and expression of image discrimination effects. Preferably, it is in the range of 1500 to 10000% by mass, and more preferably in the range of 2500 to 7000.

  These specific modified alkali-soluble resins have a dispersion phase formation property, printing durability, scratch resistance, and 1 to 1% of the total solid content of the lower recording layer from the standpoint of the effect of image discrimination. It is preferable to contain in the range of 60 mass%, It is more preferable to contain in the range of 3-40 mass%, It is still more preferable to contain in the range of 5-20 mass%.

[Other resins constituting the lower recording layer]
In the present invention, other resins constituting the lower recording layer include, for example, urethane resins, acrylic resins, styrene resins, diazo resins, amide resins, polyether resins, and specific modified alkali-soluble resins. And novolak resins (partially phenolic hydroxyl groups are not esterified).
These resins are used to form a matrix phase or a dispersed phase in the lower recording layer, but only those resins that are not compatible with the above-mentioned specific modified alkali-soluble resin are used to form the matrix phase. Can do.
The resin that is not compatible with the specific modified alkali-soluble resin, that is, the resin constituting the matrix phase is preferably a resin that is insoluble in water and soluble in an alkaline aqueous solution (alkali-soluble resin).

  Other resins constituting the lower recording layer include urethanes exemplified below in addition to copolymers having structural units derived from at least one of the monomers corresponding to the following (1) to (5): A novolak resin, a diazo resin, and a polyether resin that are not included in the base resin and the specific modified alkali-soluble resin are preferably used.

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

(In the above formulas (I) to (V), X ¹ and X ² each independently represent —O— or —NR ⁷ —. R ¹ and R ⁴ each independently represents a hydrogen atom, or ^{.R 2, R 5, R 9} , R 12 representing a CH _3, and R ¹⁶ are each independently an alkylene group which may having 1 to 12 carbon atoms which may have a substituent, a cycloalkylene group, an arylene R ³ , R ⁷ and R ¹³ each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms, a cycloalkyl group or an aryl group. R ⁶ and R ¹⁷ each independently represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group, which may have a substituent. .R ^8, R ^10, R ¹⁴ representing a each independently, Atom, halogen atom, or .R ^11, R ¹⁵ are each independently represent a CH _3, a single bond, or may have a substituent group alkylene group having 1 to 12 carbon atoms, cycloalkylene group, arylene And Y ¹ and Y ² each independently represents a single bond or —CO—.

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

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

(5) Styrenic compounds, or vinyl acetate, vinyl alcohol, for example, o-, m-, p-hydroxystyrene, p-sulfonic acid styrene, o-, m-, p-carboxyl styrene and the like.

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

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

(8) (Substitution) such as methyl methacrylate, ethyl methacrylate, pyrrole methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate Alkyl methacrylate.
(9) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.

(10) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(11) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(12) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene.
(13) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.

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

  Furthermore, monomers that can be copolymerized with these monomers may be copolymerized. These copolymers are preferably those having a weight average molecular weight of 2000 or more and a number average molecular weight of 1000 or more. More preferably, the weight average molecular weight is 5000 to 300000, the number average molecular weight is 2000 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10.

  The urethane-based resin that can be used in the present invention is preferably a resin that is insoluble in water and soluble in an alkaline aqueous solution. Specifically, for example, JP-A-63-124047, Examples thereof include, but are not limited to, the urethane polymer compounds described in JP-A Nos. 63-287946, 2-866 and 2-156241.

Examples of the novolak resin not included in the specific modified alkali-soluble resin that can be used in the present invention (part of the phenolic hydroxyl group is not esterified) include phenol formaldehyde resin, m-cresol formaldehyde resin, and p-cresol formaldehyde. Examples thereof include alkali-soluble novolak resins such as resins, m- / p-mixed cresol formaldehyde resins, and phenol / cresol (any of m-, p-, m- / p- mixed) mixed formaldehyde resins. As these alkali-soluble novolak resins, those having a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000 are used.
Further, as described in US Pat. No. 4,123,279, condensation of phenol and formaldehyde having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin. You may use a thing together.

As the diazo resin that can be used in the present invention, diazo resins, that is, polymers and oligomers having a diazonio group in the side chain are preferably used. In particular, a diazo resin that is a condensate of an aromatic diazonium salt and, for example, an active carbonyl-containing compound (eg, formaldehyde) is useful.
Preferred diazo resins include, for example, 4-diazo-diphenylamine, 1-diazo-4-N, N-dimethylaminobenzene, 1-diazo-4-N, N-diethylaminobenzene, 1-diazo-4-N-ethyl. -N-hydroxyethylaminobenzene, 1-diazo-4-N-methyl-N-hydroxyethylaminobenzene, 1-diazo-2,5-diethoxy-4-benzoylaminobenzene, 1-diazo-4-N-benzyl Aminobenzene, 1-diazo-4-morpholinobenzene, 1-diazo-2,5-dimethoxy-4-p-tolylmercaptobenzene, 1-diazo-2-ethoxy-4-N, N-dimethylaminobenzene, 1 -Diazo-2,5-dibutoxy-4-morpholinobenzene, 1-diazo-2,5-diethoxy-4-morpholine Benzene, 1-diazo-2,5-dimethoxy-4-morpholinobenzene, 1-diazo-2,5-diethoxy-4-p-tolylmercaptobenzene, 1-diazo-3-ethoxy-4-N-methyl- N-benzylaminobenzene, 1-diazo-3-chloro-4-N, N-diethylaminobenzene, 1-diazo-3-methyl-4-pyrrolidinobenzene, 1-diazo-2-chloro-4-N, N -Dimethylamino-5-methoxybenzene, 1-diazo-3-methoxy-4-pyrrolidinobenzene, 3-methoxy-4-diazodiphenylamine, 3-ethoxy-4-diazodiphenylamine, 3- (n-propoxy) -4 A diazo monomer such as diazodiphenylamine, 3-isopropoxy-4-diazodiphenylamine, formaldehyde, A condensing agent such as toaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, benzaldehyde and a molar ratio of 1: 1 to 1: 0.5, preferably 1: 0.8 to 1: 0.6, respectively. A reaction product obtained by reacting an anion with the condensate obtained by condensation in step (b).

  Examples of the anion used for the reaction include tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, and 2,5-dimethylbenzenesulfonic acid. 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, di-t-butylnaphthalene Examples include sulfonic acid, 1-naphthol-5-sulfonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid. Among these, alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalene sulfonic acid and 2,5-dimethylbenzene sulfonic acid are particularly preferable.

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

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

(In the above general formula (1) and general formula (2), R ¹ , R ² , R ³ , R ⁴ , and R ⁵ are each independently a hydrogen atom or a halogen atom (eg, fluorine, chlorine, bromine). , —COOH, —OPO ₃ H ₂ , —PO ₃ H ₂ , —SO ₃ H, —OH, substituents (eg, —COOH, —OPO ₃ H ₂ , —PO ₃ H ₂ , —SO ₃ H, — OH) which may have a hydrocarbon group having 15 or less carbon atoms (for example, carboxymethyl group, hydroxyethyl group, p-carboxymethoxyphenyl group), an alkoxy group which may have a similar substituent ( For example, a methoxy group, a hexyloxy group, a carboxymethoxy group), or an aryloxy group (for example, a phenoxy group, a p-carboxymethoxyphenoxy group) which may have a similar substituent, Y represents NR ⁶ , Indicates O or S R ⁶ is a hydrogen atom, or more than 12 hydrocarbon group having a carbon (e.g., a methyl group, an ethyl group, a hexyl group), also, X ^-. Is PF ₆ ^-, or the number 20 following substituents carbon Benzene sulfonate which may have, and naphthalene sulfonate which may have a substituent having 20 or less carbon atoms, such as a methyl group, a butyl group (n-, i-, sec-, and t-butyl groups), hexyl group, decyl group, dodecyl group, and benzoyl group.

  As described above, the other resins constituting the lower recording layer have been described. In addition to the resins described herein, depending on the purpose, a polymer compound (hereinafter, referred to below) that is insoluble in water and can be used in an alkaline aqueous solution. It may be simply referred to as an alkali-soluble polymer compound).

  Form of a lower recording layer having a matrix phase and a dispersed phase formed by using two or more of these incompatible resins, that is, a lower recording layer having a dispersed phase obtained by the method (1) This form is also called sea-island structure. In the present invention, the observation of the sea-island structure is carried out by making a cross section of a positive recording layer obtained by cutting a lithographic printing plate precursor with a microtome or the like, and then taking a photograph with a scanning electron microscope (SEM) to obtain a circle or an ellipse. The size of the dispersed phase can be evaluated by an image analyzer. If the image is unclear when photographed, the lower recording layer cross-section can be obtained, for example, by using a solvent according to the method described in “Polymer alloy and polymer blend” (LA UTRACKI, translated by Toshio Nishi; Tokyo Chemical Dojin). By shooting after processing by etching, a clearer image can be obtained.

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

Hereinafter, a preferred method for forming a dispersed phase in the sea-island structure of the lower recording layer will be described.
In the present invention, the selection of the coating solvent is an important factor for setting the dispersed phase in the sea-island structure of the lower recording layer to a maximum major axis of 0.8 μm or less and an average major axis of 0.6 μm or less. By using it, a dispersed phase having a desired size can be formed.
Although there is no clear logic for reducing the dispersed phase by selecting a coating solvent system, as coating solvents, ketone systems such as cyclohexanone and methyl ethyl ketone, methanol, ethanol, propanol, 1-methoxy-2-propanol, etc. Alcohol, cellosolve such as ethylene glycol monomethyl ether, lactone such as γ-butyrolactone, sulfoxide such as dimethyl sulfoxide and sulfolane, halogen such as ethylene dichloride, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate Such as acetates, ethers such as dimethoxyethane, esters such as methyl lactate and ethyl lactate, amides such as N, N-dimethoxyacetamide and N, N-dimethylformamide, N-methylpyrrolidone, etc. It is preferable to use loridone, urea such as tetramethylurea, aromatic such as toluene, etc. Among them, methyl ethyl ketone, 1-methoxy-2-propanol, ethylene glycol monomethyl ether, γ-butyrolactone, dimethyl sulfoxide, etc. preferable. These solvents may be used alone or in combination.

  In order to make the size of the dispersed phase in the sea-island structure of the lower recording layer predetermined, in addition to the coating solvent system described above, after coating the lower recording layer coating solution, the undried coating film is dried. Conditions are also known to be important factors. Regarding the method for forming such a sea-island structure, reference can be made to the description in JP-A-9-90610.

When the lower recording layer is formed using these two or more kinds of incompatible resins, a resin (specific modified alkali-soluble resin in the present invention) exhibiting stronger interaction such as hydrogen bonding and ionicity, Since it is easy to form a spherical shape or a flat spherical shape between other resins, a dispersed phase is formed. In the present invention, the lower recording layer contains an infrared absorber described later in addition to these resins. However, since this infrared absorber is ionic or a coordination complex, the resin exhibits a stronger interaction. It has the property of being easily taken in. For this reason, when the lower recording layer is formed, if an infrared absorber coexists with two or more resins that are incompatible with each other, a large amount of the infrared absorber is contained in the dispersed phase. Furthermore, similarly, when an acid generator or a radical generator coexists, since the acid generator or radical generator initiator usually has a high polar group such as an onium salt structure, triazine, or sulfonate, Like the absorbent, it is easily incorporated into the dispersed phase.
For these reasons, the infrared absorber, the acid generator or the radical generator is localized in the dispersed phase formed in the lower recording layer.

  Such a lower recording layer contains a high concentration of an infrared absorber and a compound (acid generator or radical generator) whose solubility in an alkaline solution is changed by heat in the dispersed phase. The disperse phase can efficiently improve the solubility in an alkaline aqueous solution by exposure.

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

In this case, examples of the substance included in the capsule and the substance included in the latex include an acid generator, a radical generator, a photothermal conversion material, and a crosslinking agent in addition to the specific modified alkali-soluble resin.
In the lower recording layer having the dispersed phase by the method (2), as the resin constituting the matrix phase, the resins listed in [Other resins constituting the lower recording layer] are used in the same manner. can do.

[Other components constituting the lower recording layer]
In the present invention, the lower recording layer contains an infrared absorber and an acid generator capable of improving the solubility in the alkaline aqueous solution of the exposed portion and generating an acid by being decomposed by light or heat. Cost.
Hereinafter, in addition to the infrared absorber and acid generator contained in the lower recording layer, other optional components will be described. The components shown below can be contained in the positive recording layer (upper recording layer) other than the lower recording layer in the same manner, and therefore will be described collectively as constituent components of the positive recording layer.

(Infrared absorber)
The positive recording layer of the present invention contains an infrared absorber. This infrared absorber has a function of converting the absorbed infrared rays into heat, and the laser scanning causes the cancellation of the interaction, the decomposition of the development inhibitor, the generation of acid, etc., and the solubility in the developer is greatly increased. . In addition, the infrared absorber itself may form an interaction with the above-described various resins to suppress the solubility in an alkaline aqueous solution.
In addition, when such an infrared absorber is included in the dispersed phase in the lower recording layer, the infrared absorber is localized in the dispersed phase, and an interaction release agent or an acid generator is included in the dispersed phase. In the case where coexists, it is considered that the decomposability is improved.

The infrared absorber used in the present invention is a dye or pigment that effectively absorbs infrared rays having a wavelength of 760 nm to 1200 nm. A dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm is preferable.
Below, the infrared absorber which can be used conveniently in this invention is explained in full detail.
As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.

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

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

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

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

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

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

  The particle diameter of the pigment is preferably in the range of 0.01 μm to 10 μm, and more preferably in the range of 0.05 μm to 1 μm, from the viewpoints of stability in the coating solution and uniformity of the positive recording layer. It is particularly preferable that the thickness is in the range of 0.1 μm to 1 μm.

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

Furthermore, in the present invention, an anionic infrared absorber described in Japanese Patent Application No. 10-237634 can also be suitably used. This anionic infrared absorber refers to one having an anion structure without a cation structure in the mother nucleus of a dye that substantially absorbs infrared rays.
For example, (a-1) anionic metal complex and (a-2) anionic phthalocyanine are mentioned.
Here, the (a-1) anionic metal complex refers to an anion that becomes an anion in the central metal and the entire ligand of the complex part that substantially absorbs light.
(A-2) Anionic phthalocyanine refers to a phthalocyanine skeleton having an anion group such as a sulfonic acid, a carboxylic acid, or a phosphonic acid group bonded as a substituent to form an anion as a whole.
In addition, the Japanese Patent Application No. Hei 10-237634 described in [0014] to ^{[0105] [Ga - -M-} Gb] m X m anionic infrared absorber represented by ⁺ [Ga ^- represents an anionic substituent , Gb represents a neutral substituent. X ^{m +} represents a 1 to m-valent cation containing a proton, and m represents an integer of 1 to 6. Can be mentioned.

  In the present invention, an infrared absorber that generates a positive action (dissolution in the alkaline aqueous solution is suppressed in the unexposed area and the dissolution inhibiting action is canceled in the exposed area) by the interaction with each resin described above is used. It is preferable. Therefore, among the infrared absorbers described above, those having an onium salt structure and an anionic infrared absorber are preferably used. In particular, the above-described dyes having an onium salt structure such as cyanine dyes and pyrylium salts, and infrared absorbers having an onium salt structure described in paragraphs [0018] to [0034] of JP-A No. 11-291652 are particularly preferred. Preferably used.

In the present invention, the infrared absorber is 0.01 to about the total solid content of each recording layer in the lower recording layer and other positive recording layers, from the viewpoint of image forming property and suppression of occurrence of contamination in non-image areas. It is preferable to add 50% by weight, more preferably 0.1 to 20% by weight, and still more preferably 0.5 to 15% by weight.
These infrared absorbers may be used alone or in combination of two or more, and a dye and a pigment may be used in combination.

Further, the infrared absorber may be contained in either the matrix phase or the dispersed phase, or may be contained in both.
In addition, when a desired component such as an acid generator or an infrared absorber is contained in the latex constituting the dispersed phase as described above, it may be added together with the raw material when forming the latex particles, or introduced after the latex is formed. May be.
Examples of the method of introducing after forming the latex include a method in which desired components such as an acid generator and an infrared absorber to be introduced are dissolved in an organic solvent in a latex dispersed in an aqueous system and added to a dispersion medium.

  The positive recording layer in the present invention preferably does not cause ablation in connection with the infrared laser irradiation apparatus. From the viewpoint of preventing ablation, any polymeric material that is a binder constituting the recording layer can be used as long as the solubility in an alkaline aqueous solution, that is, an alkaline developer is changed by application of thermal energy. However, from the viewpoint of easy availability and difficulty in ablation, it is preferable to use a polymer compound that is insoluble in water and soluble in alkaline water.

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

(Acid generator)
The positive recording layer in the present invention contains an acid generator that decomposes with light or heat to generate an acid in order to improve the solubility of the exposed portion in an alkaline aqueous solution.
Here, the acid generator means a compound that generates an acid upon irradiation with light having a wavelength of 200 to 500 nm or heating at 100 ° C. or higher. And the like, known photodegradants, photochromic agents, known acid generators used in microresists, and the like, known pyrolytic compounds that generate acid upon decomposition, and mixtures thereof. The acid generated is preferably a strong acid having a pKa of 2 or less, such as sulfonic acid and hydrochloric acid.

  Examples of the acid generator suitably used in the present invention include triazine compounds described in JP-A No. 11-95415, and latent Bronsted acids described in JP-A No. 7-20629. Here, the latent Bronsted acid refers to a precursor that decomposes to produce a Bronsted acid. In the present invention, as the Bronsted acid, an ionic latent Bronsted acid can be preferably used. The ionic latent Bronsted acids include onium salts, particularly iodonium, sulfonium, phosphonium, selenonium, diazonium, and arsonium salts. Specific examples of particularly useful onium salts include diphenyliodonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, phenylmethyl-ortho-cyanobenzylsulfonium trifluoromethanesulfonate, and 2-methoxy-4-aminophenyldiazonium hexafluoro. Examples include phosphate.

  Also, any onium salt described in US Pat. No. 4,708,925 can be used as the latent Bronsted acid of the present invention. These include indonium, sulfonium, phosphonium, bromonium, chloronium, oxysulfoxonium, oxysulfonium, sulfoxonium, selenonium, telluronium and arsonium salts.

  Among these, useful ionic latent Bronsted acids are those represented by the following formula.

In the above formula, when X is iodine, R ³ and R ⁴ are a lone pair, and R ¹ and R ² are an aryl or substituted aryl group. When X is S or Se, R ⁴ may be a lone pair, and R ¹ , R ² and R ³ may be an aryl group, a substituted aryl group, an aliphatic group or a substituted aliphatic group. When X is P or As, then R ⁴ may be an aryl group, a substituted aryl group, an aliphatic group or a substituted aliphatic group. W can be BF ₄ , CF ₃ SO ₃ , SbF ₆ , CCl ₃ CO ₂ , ClO ₄ , AsF ₆ , PF ₆ , or any corresponding acid whose pH is less than 3.
In the present invention, it is particularly preferable to use a diazonium salt as the ionic latent Bronsted acid.

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

  In the present invention, these acid generators are 0.01% relative to the total solid content of each recording layer in the lower recording layer and other positive recording layers from the viewpoint of image forming properties and prevention of stains in the non-image area. It is added at a ratio of ˜50 wt%, preferably 0.1 to 25 wt%, more preferably 0.5 to 20 wt%.

(Water-insoluble and alkali-soluble polymer compounds)
In the positive recording layer of the present invention, a water-insoluble / alkali-soluble polymer compound can be used depending on the purpose. This water-insoluble / alkali-soluble polymer compound can be used as a material constituting the lower recording layer. In this case, the polymer compound constitutes a matrix phase or a dispersed phase.
Here, the water-insoluble / alkali-soluble polymer compound includes a homopolymer containing an acidic group in the main chain and / or side chain in the polymer, a copolymer thereof, or a mixture thereof. Therefore, a positive recording layer containing a water-insoluble / alkali-soluble polymer compound has a property of dissolving when contacted with an alkali developer.

  The water-insoluble / alkali-soluble polymer compound used in the positive recording layer in the present invention is not particularly limited as long as it is a conventionally known one, but (A) a phenolic hydroxyl group, (B) a sulfonamide group, (C) A polymer compound having any functional group of an active imide group in the molecule is preferable. For example, the following are exemplified, but not limited thereto.

(A) Examples of the polymer compound having a phenolic hydroxyl group include phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- / p-mixed cresol formaldehyde resin, phenol / cresol (m-, p Any of-or m- / p-mixing) may be mentioned, including novolak resins such as mixed formaldehyde resins and pyrogallol acetone resins. Furthermore, as described in US Pat. No. 4,123,279, a phenol having a C 3-8 alkyl group as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin. Also preferred is a condensation polymer of aldehyde and formaldehyde.
In addition to this, a polymer compound having a phenolic hydroxyl group in the side chain is preferably used as the polymer compound having a phenolic hydroxyl group. As the polymer compound having a phenolic hydroxyl group in the side chain, a polymerizable monomer composed of a low molecular compound having at least one unsaturated bond polymerizable with the phenolic hydroxyl group is homopolymerized, or other polymerizable property is added to the monomer. Examples thereof include a polymer compound obtained by copolymerizing monomers.

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

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

(C) The polymer compound having an active imide group is preferably one having an active imide group in the molecule. As the polymer compound, one unsaturated bond polymerizable with the active imide group is present in one molecule. Examples thereof include a high molecular compound obtained by homopolymerizing a polymerizable monomer comprising the above-described low molecular weight compound or copolymerizing the monomer with another polymerizable monomer.
As such a compound, specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

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

  In the present invention, the water-insoluble / alkali-soluble polymer compound is a polymerizable monomer having a phenolic hydroxyl group, a polymerizable monomer having a sulfonamide group, a polymerizable monomer having an active imide group, and another polymerizable monomer. In the case of a copolymer, the monomer imparting alkali solubility is preferably contained in an amount of 10 mol% or more, more preferably 20 mol% or more. When the copolymerization component is less than 10 mol%, alkali solubility tends to be insufficient, and the development latitude improvement effect may not be sufficiently achieved.

  Examples of the monomer component to be copolymerized with the polymerizable monomer having a phenolic hydroxyl group, the polymerizable monomer having a sulfonamide group, or the polymerizable monomer having an active imide group include the compounds listed in the following (m1) to (m12). However, the present invention is not limited to these.

(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, and glycidyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.

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

  As a copolymerization method of these various monomers, conventionally known graft copolymerization method, block copolymerization method, random copolymerization method and the like can be used.

The water-insoluble / alkali-soluble polymer compound used in the upper recording layer is a phenolic hydroxyl group in that strong hydrogen bonding occurs in the unexposed area and some hydrogen bonds are easily released in the exposed area. It is desirable that the polymer compound has More desirably, it is a novolac resin.
These water-insoluble and alkali-soluble polymer compounds preferably have a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000.

(Additive)
In the positive recording layer of the present invention, various known additives can be used in combination with the above-mentioned components depending on the purpose. As the additive described here, the same materials can be used for the lower recording layer and the other recording layers.

-Fluorine-containing polymer-
In the positive recording layer of the present invention, a fluoropolymer can be added for the purpose of improving the development resistance of the image area. Examples of the fluorine-containing polymer used include fluorine-containing monomer copolymers as described in JP-A Nos. 11-288093 and 2000-187318.
Preferable specific examples include acrylic polymers containing fluorine of P-1 to P-13 described in JP-A No. 11-288093 and A-1 to JP-A No. 2000-187318. A fluorine-containing polymer obtained by copolymerizing an acrylic monomer containing fluorine with A33 with any acrylic monomer can be used.
As the molecular weight of the fluorine-containing polymer mentioned above, those having a weight average molecular weight of 2000 or more and a number average molecular weight of 1000 or more are preferably used. More preferably, the weight average molecular weight is 5000 to 300000, and the number average molecular weight is 2000 to 250,000.

In addition, as the fluorine-containing polymer, a commercially available fluorine-based surfactant that is a compound having the preferred molecular weight can also be used. Specific examples include Megafac F-171, F-173, F-176, F-183, F-184, F-780, F-781 (all trade names) manufactured by Dainippon Ink and Chemicals, Inc. Can be mentioned.
These fluorine-containing polymers may be used alone or in combination of two or more.
Further, the addition amount is preferably 1.4% by mass or more, and 1.4 to 5.0% by mass with respect to the total solid content of each positive recording layer from the viewpoint of development resistance and solubility. % Is more preferable.

-Dissolution inhibitor-
If necessary, the positive recording layer in the present invention is thermally decomposable, such as an onium salt, a quinonediazide compound, an aromatic sulfone compound, and an aromatic sulfonic acid ester compound. A substance that substantially lowers the solubility of each of the polymer compounds (each of the above-described resins and water-insoluble / alkali-soluble polymer compounds) can be added as a dissolution inhibitor. The addition of this dissolution inhibitor improves the dissolution inhibition of the image area in the developer, and the addition of this substance causes an interaction between the polymer compound capable of forming an aqueous alkaline solution as an infrared absorber. It is also possible to use what is not formed.

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

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

In the present invention, a diazonium salt is particularly preferable. Particularly suitable diazonium salts include those described in JP-A-5-158230.
The counter ion of the onium salt includes tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfone Examples include acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid. Of these, particularly preferred are alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid.
The amount of the dissolution inhibitor such as onium salt added is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass with respect to the total solid content of each positive recording layer. %.

(Other additives)
Further, for the purpose of enhancing the discrimination of the image and the resistance to scratches on the surface, a perfluoroalkyl group having 3 to 20 carbon atoms in the molecule as described in JP-A-2000-87318. A polymer having a (meth) acrylate monomer having 2 or 3 as a polymerization component can be added.
Furthermore, for the purpose of improving sensitivity, cyclic acid anhydrides, phenols, and organic acids can be used in combination. Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endooxy-Δ4-tetrahydrophthalic anhydride described in US Pat. No. 4,115,128, Trachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ′, 4 “-Trihydroxytriphenylmethane, 4,4 ′, 3”, 4 ”-tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane and the like. There are sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphoric acid esters, carboxylic acids and the like described in Japanese Laid-Open Patent Application No. 60-88942, JP-A-2-96755, and the like. p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenyl Suphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-methoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2 -Dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid, etc. The proportion of the cyclic acid anhydride, phenols and organic acids in the printing plate material is 0.05 to 20 mass. % Is preferable, more preferably 0.1 to 5% by mass, and particularly preferably 0.1 to 10% by mass.

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

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

Further, in the positive recording layer of the present invention, a nonionic interface as described in JP-A-62-251740 and JP-A-3-208514 is used in order to broaden the processing stability against development conditions. Activators, amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, siloxane-based compounds as described in EP950517, JP-A-11-288093 A copolymer containing a fluorine monomer as described in the publication can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like. Specific examples of the double-sided activator include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Co., Ltd.) and the like. As the siloxane compound, a block copolymer of dimethylsiloxane and polyalkylene oxide is preferable. Specific examples include DBE-224, DBE-621, DBE-712, DBP- manufactured by Chisso Corporation. And polyalkylene oxide-modified silicones such as 732, DBP-534, and Tego Glide 100 manufactured by Tego, Germany.
The addition amount of the nonionic surfactant and the amphoteric surfactant is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass with respect to the total solid content of each positive recording layer. is there.

In the positive recording layer of the present invention, a printing-out agent for obtaining a visible image immediately after exposure can be added. Typical examples of the printing-out agent include a combination of a compound that generates an acid upon exposure (a photoacid releasing agent) and an organic dye that can form a salt.
Specifically, for example, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A Nos. 50-36,209 and 53-8128, Trihalomethyl compounds and salts described in JP-A Nos. 53-36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440 Examples of such trihalomethyl compounds include oxazole-based compounds and triazine-based compounds, both of which have excellent temporal stability and give clear printout images. Examples of other photoacid releasing agents include various o-naphthoquinonediazide compounds described in JP-A-55-62444; 2-trihalomethyl-5--5 described in JP-A-55-77742. Examples include aryl-1,3,4-oxadiazole compounds; diazonium salts.

[Manufacture of lithographic printing plate precursor]
The lithographic printing plate precursor according to the invention is usually produced by sequentially coating a lower recording layer coating solution obtained by dissolving the above-described components in a solvent, and further an upper recording layer coating solution on a suitable support. be able to.
Suitable solvents for the lower recording layer coating solution and the upper recording layer coating solution are ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl. Acetate, 1-methoxy-2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ- Examples thereof include butyrolactone and toluene, but are not limited thereto. These solvents are used alone or in combination. The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass.
In principle, the lower recording layer and the upper recording layer are preferably formed by separating the two layers.

As a method for forming the two layers separately, for example, a method using a difference in solvent solubility between a component contained in the lower recording layer and a component contained in the upper recording layer, or an upper recording layer is formed. Although the method of drying and removing a solvent rapidly after apply | coating etc. is mentioned, It is not limited to these.
As a method of utilizing the difference in solvent solubility between the component contained in the lower recording layer and the component contained in the upper recording layer, when applying the upper recording layer coating liquid, the matrix phase or dispersed phase of the lower recording layer is used. The method of using the solvent which does not melt | dissolve resin which comprises is mentioned. Thereby, even if it carries out 2 layer application | coating, it becomes possible to isolate | separate each layer clearly and to make a coating film. For example, as the lower recording layer component, a solvent-insoluble component such as methyl ethyl ketone or 1-methoxy-2-propanol that dissolves the alkali-soluble resin that is the upper recording layer component is selected, and the lower recording layer component is dissolved. The lower recording layer can be applied and dried using, and then the upper recording layer mainly composed of alkali-soluble resin can be dissolved in methyl ethyl ketone or 1-methoxy-2-propanol, and then applied and dried to form two layers. become.

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

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

  Next, after applying the second layer (upper recording layer), as a method of drying the solvent very quickly, high-pressure air is blown from a slit nozzle installed substantially perpendicular to the running direction of the web, steam, etc. The heating medium can be achieved by applying thermal energy as conduction heat from the lower surface of the web from a roll (heating roll) supplied inside, or by combining them.

In the present invention, various coating methods can be used for forming the lower recording layer and the upper recording layer. For example, bar coater coating, spin coating, spray coating, curtain coating, dip coating, Air knife coating, blade coating, roll coating and the like can be mentioned.
In particular, in order to prevent damage to the lower recording layer when the upper recording layer is applied, the upper recording layer is preferably applied in a non-contact manner. Further, although it is possible to use a bar coater coating as a method generally used for solvent-based coating, which is a contact type, it is desirable to apply by forward driving in order to prevent damage to the lower recording layer. .

The coating amount after drying of the lower recording layer in the planographic printing plate precursor of the present invention is in the range of 0.5 to 1.5 g / m ² from the viewpoint of securing printing durability and suppressing the occurrence of residual film during development. Is more preferable, and the range of 0.7 to 1.0 g / m ² is more preferable.
The coating amount after drying of the upper recording layer is preferably in the range of 0.05 to 1.0 g / m ^2, more preferably in the range of 0.07~0.7g / m ^2. In addition, when there are two or more upper recording layers, the total amount is shown.

  In each of these positive recording layers, generally, as the coating amount decreases, the apparent sensitivity increases, but the development latitude and film characteristics tend to decrease. In particular, when the thickness of the recording layer is too thick, the recording layer is easily affected by thermal diffusion in the deep part, and there is a concern that the image formability in the vicinity of the support is lowered.

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

  Furthermore, a plasticizer is added to the coating liquid for the lower recording layer and / or the upper recording layer of the present invention, if necessary, in order to impart flexibility of the coating film. Examples of the plasticizer include butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, and tetrahydrofurfuryl oleate. And oligomers and polymers of acrylic acid or methacrylic acid.

[Support]
The support used in the present invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), metal Plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, Polyvinyl acetal, etc.), paper laminated with metal as described above, or vapor-deposited paper, or plastic film.
As the support used in the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of different elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10% by mass. Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements. Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

  Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used. The roughened aluminum plate is subjected to an alkali etching treatment and neutralization treatment as necessary, and then subjected to an anodization treatment to enhance the water retention and wear resistance of the surface as desired. As an electrolyte used for anodizing treatment of an aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.

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

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

The planographic printing plate precursor of the present invention is provided by laminating at least two layers of the lower recording layer and the upper recording layer on a support, and if necessary, between the support and the lower recording layer. An undercoat layer can be provided.
Various organic compounds are used as an undercoat layer component. For example, phosphonic acids having an amino group such as carboxymethylcellulose, dextrin, gum arabic, 2-aminoethylphosphonic acid, and optionally substituted phenylphosphonic acid Organic phosphonic acids such as naphthylphosphonic acid, alkylphosphonic acid, glycerophosphonic acid, methylenediphosphonic acid and ethylenediphosphonic acid, optionally substituted phenylphosphoric acid, naphthylphosphonic acid, alkylphosphoric acid and glycerophosphoric acid Organic phosphoric acid, optionally substituted phenylphosphinic acid, naphthylphosphinic acid, alkylphosphinic acid, glycerophosphinic acid and other organic phosphinic acids, glycine and β-alanine amino acids, and triethanolamine hydrochloric acid Has a hydroxy group such as salt -Alanine, and hydrochlorides of amines that may be used in combination of two or more.

This organic undercoat layer can be provided by the following method. That is, a method in which a solution obtained by dissolving the above organic compound in water or an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof is applied on an aluminum plate and dried, and water, methanol, ethanol, methyl ethyl ketone, etc. In this method, an aluminum plate is immersed in a solution obtained by dissolving the above organic compound in an organic solvent or a mixed solvent thereof to adsorb the above compound, and then washed with water and dried to provide an organic undercoat layer. . In the former method, a solution having a concentration of 0.005 to 10% by mass of the organic compound can be applied by various methods. In the latter method, the concentration of the solution is 0.01 to 20% by mass, preferably 0.05 to 5% by mass, the immersion temperature is 20 to 90 ° C., preferably 25 to 50 ° C., and the immersion time is 0.1 second to 20 minutes, preferably 2 seconds to 1 minute. The solution used for this can be adjusted to a pH range of 1 to 12 with a basic substance such as ammonia, triethylamine or potassium hydroxide, or an acidic substance such as hydrochloric acid or phosphoric acid. A yellow dye can also be added to improve the tone reproducibility of the image recording material.
The coating amount of the organic undercoat layer is suitably ² to 200 mg / m ² , preferably 5 to 100 mg / m ² . If the coating amount is less than 2 mg / m ² , sufficient printing durability cannot be obtained. Moreover, even if it is larger than 200 mg / m ^2, it is the same.

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

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

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

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

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

  When developing using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than the developer is added to the developer so that a large amount of PS can be obtained without replacing the developer in the developer tank for a long time. It is known that plates can be processed. This replenishment method is also preferably applied in the present invention. Various surfactants and organic solvents can be added to the developer and replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area. Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. If necessary, the developer and replenisher may contain reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids such as sodium salts and potassium salts, organic carboxylic acids, antifoaming agents, and hard water softeners. It can also be added. The printing plate developed using the developer and the replenisher is post-treated with water-washing water, a rinsing solution containing a surfactant and the like, a desensitizing solution containing gum arabic and starch derivatives. When the lithographic printing plate precursor according to the invention is used as a printing plate, these treatments can be used in various combinations as post-treatments.

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

  A method for processing a lithographic printing plate precursor according to the present invention will be described. If the lithographic printing plate obtained by image exposure, development, rinsing and / or rinsing and / or gumming has unnecessary image areas (for example, film edge marks of the original film) Unnecessary image portions are erased. Such erasing is preferably performed by applying an erasing solution to an unnecessary image portion as described in Japanese Patent Publication No. 2-13293, leaving it for a predetermined time, and then washing with water. A method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber as described in JP-A-5-174842 can also be used.

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

In general, the amount of surface-adjusting solution applied is suitably 0.03 to 0.8 g / m ² (dry mass). The lithographic printing plate coated with the surface-adjusting liquid is dried if necessary, and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). The The heating temperature and time in this case are preferably in the range of 180 to 300 ° C. and in the range of 1 to 20 minutes, although depending on the type of components forming the image.
The lithographic printing plate that has been burned can be subjected to conventional treatments such as washing and gumming as needed, but a surface-conditioning solution containing a water-soluble polymer compound or the like is used. If so, so-called desensitizing treatment such as gumming can be omitted.
The lithographic printing plate obtained by such processing is applied to an offset printing machine or the like and used for printing a large number of sheets.

EXAMPLES Hereinafter, although this invention is demonstrated according to an Example, the scope of the present invention is not limited to these Examples.
(Examples 1-3)
[Production of support]
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.014 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: It contains 0.03% by mass, and the balance is prepared using Al and an inevitable impurity aluminum alloy. After the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Created. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, the temperature was kept constant at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Further, heat treatment was performed at 500 ° C. using a continuous annealing machine, and then finished into an aluminum plate having a thickness of 0.24 mm by cold rolling. After making this aluminum plate into width 1030mm, it used for the surface treatment shown below.

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

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

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

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

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10.5 g / L aqueous solution of nitric acid (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions) at a liquid temperature of 80 ° C.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Then, water washing by spraying was performed.

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

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

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

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

(I) Formation of undercoat layer On the aluminum support after the alkali metal silicate treatment obtained as described above, an undercoat layer coating solution having the following composition was applied and dried at 80 ° C for 15 seconds. An undercoat layer was formed. The coating amount of the undercoat layer after drying was 15 mg / m ² .

<Coating liquid for undercoat layer>
・ The following compound 1 0.3g
・ Methanol 100g
・ Water 1g

On the formed undercoat layer, the following lower recording layer coating solution was applied so that the coating amount was 0.85 g / m ^2, and then Wind Control was set to 7 with PERBECT OVEN PH200 manufactured by TABAI. dried for 50 seconds at 140 ° Te, then, after the coating amount of the upper recording layer coating solution having the following was coated so as to be 0.15 g / m ^2, and dried for 1 minute at 120 ° C., the lithographic printing plate precursor 1 3 was obtained.

[Coating liquid for lower recording layer]
N- (4-aminosulfonylphenyl) methacrylamide / acrylonitrile / methyl methacrylate (addition amount Ag described in Table 2 below)
(36/34/30: weight average molecular weight 100,000, acid value 2.65)
Specific modified alkali-soluble resin A-1 (the following structure) (addition amount Bg described in Table 2 below)
・ Cyanine dye A (the following structure) 0.109 g
・ 4,4′-bishydroxyphenylsulfone (addition amount Cg described in Table 2 below)
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Fluorosurfactant (Surface improving surfactant) 0.035 g
(Megafuck F781F, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 24.38g
・ 13.0 g of 1-methoxy-2-propanol
・ 14.2 g of γ-butyrolactone

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

(Examples 4 to 6)
Lithographic printing plate precursors 4 to 6 were obtained in the same manner as in Example 1 except that the lower recording layer coating solution used in Example 1 was changed to the following.

[Coating liquid for lower recording layer]
N- (4-aminosulfonylphenyl) methacrylamide /
Acrylonitrile / methyl methacrylate (addition amount Dg described in Table 3 below)
(36/34/30: weight average molecular weight 100,000, acid value 2.65)
Specific modified alkali-soluble resin A-1 (the above structure) (addition amount Eg described in Table 3 below)
・ Dye C (the following structure) 0.109g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
P-Toluenesulfonic acid (addition amount Fg described in Table 3 below)
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Methyl ethyl ketone 25.36g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-butyrolactone 13.2 g

(Example 7)
A lithographic printing plate precursor 7 was obtained in the same manner as in Example 1 except that the application amount of the upper recording layer in Example 1 was 0.20 g / m ² .

(Example 8)
In the production of the support in Example 1, (h) no alkali metal silicate treatment was performed, and (i) in the formation of the undercoat layer, an undercoat layer coating solution having the following composition was applied, and 30 at 80 ° C. A lithographic printing plate precursor 8 was obtained in the same manner as in Example 1 except that drying was performed for ² seconds and the coating amount after drying was changed to 10 mg / m ² .

<Coating liquid for undercoat layer>
・ Β-Alanine 0.1g
・ Phenylsulfonic acid 0.05g
・ Methanol 40g
・ Pure water 60g

Example 9
[Production of support]
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.025 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: It contains 0.03% by mass, and the balance is prepared by using an aluminum alloy of Al and inevitable impurities. After the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Created. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, the temperature was kept constant at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Further, after heat treatment was performed at 500 ° C. using a continuous annealing machine, an aluminum plate having a thickness of 0.30 mm was finished by cold rolling. After making this aluminum plate 1030 mm in width, the following surface treatment was continuously performed.

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

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

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

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 35 ° C.
The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 197 C / dm ^{2 as} the total amount of electricity when the aluminum plate was the anode. Then, water washing by spraying was performed.

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

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

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

(H) Alkaline Etching Treatment Etching was performed by spraying a caustic soda aqueous solution having a caustic soda concentration of 4.5% by mass and an aluminum ion concentration of 0.5% by mass with an aluminum dissolution amount of 0.16 g / m ² . Then, water washing by spraying was performed. The temperature for the alkali etching treatment was 70 ° C. Then, water washing by spraying was performed.

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

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

(K) Formation of undercoat layer An undercoat layer coating solution having the same composition as that used in Example 1 was applied on the aluminum support after the alkali metal silicate treatment obtained as described above. And dried at 80 ° C. for 15 seconds to form an undercoat layer. The coating amount of the coating film after drying was 15 mg / m ² .
A lithographic printing plate precursor 9 was obtained in the same manner as in Example 1 except that the support thus obtained was used.

(Example 10)
The lithographic printing plate precursor 10 was prepared in the same manner as in Example 1 except that the specific modified alkali-soluble resin A-1 in the lower recording layer coating solution in Example 1 was replaced with the specific modified alkali-soluble resin A-2 having the following structure. Got.

(Comparative Example 1)
A lithographic printing plate precursor 11 was obtained in the same manner as in Example 1 except that the lower recording layer coating solution of Example 1 was changed to the following.

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

(Comparative Example 2)
A lithographic printing plate precursor 12 was obtained in the same manner as in Example 1 except that the lower recording layer coating solution of Example 1 was changed to the following.

[Coating liquid for lower recording layer]
・ PD-1 (the following structure) 2.133g
・ Cyanine dye A (the above structure) 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-Methoxy-4-diazodiphenylamine
Hexafluorophosphate 0.030g
・ The counter ion of ethyl violet is changed to 6-hydroxynaphthalene sulfone 0.10 g
・ Fluorine-based surfactant (surfactant for improving coated surface) 0.035 g
(Megafuck F176 (20%), manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 25.38g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-butyrolactone 13.2 g

(Confirmation of dispersed phase)
Conductivity was imparted to the positive-type recording layer sections obtained by cutting the lithographic printing plate precursors 1 to 10 in Examples 1 to 10 and the lithographic printing plate precursors 12 and 13 in Comparative Examples 1 and 2 with a microtome or the like. Then, when it photographed and observed with the scanning electron microscope (SEM), it was confirmed that the disperse phase exists in each lower recording layer of Examples 1-9. The size of the dispersed phase was in the range of 0.05 to 0.55 μm. On the other hand, the lower recording layer of Comparative Example 1 and Comparative Example 2 was a uniform phase, and no dispersed phase was observed.

[Evaluation of lithographic printing plate precursor]
[Evaluation of sensitivity]
The lithographic printing plate precursors 1 to 12 obtained in the examples and comparative examples were drawn in a test pattern in the form of an image by changing the exposure energy with a Trend setter manufactured by Creo.
Thereafter, development is performed with a developer DT-2 (diluted to a conductivity of 43 mS / cm) manufactured by Fuji Photo Film Co., Ltd., and the exposure energy that can develop the non-image area with this developer is measured. did. The smaller the numerical value, the higher the sensitivity. The results are shown in Table 4 below.

[Evaluation of development latitude]
A test pattern was drawn on the planographic printing plate precursors 1 to 12 obtained in Examples and Comparative Examples using a Trend setter manufactured by Creo at a beam intensity of 9 w and a drum rotation speed of 150 rpm.
First, a PS processor 940HII manufactured by Fuji Photo Film Co., Ltd., in which the lithographic printing plate precursors 1 to 12 exposed under the above conditions were prepared by changing the dilution ratio of the developer DT-2 manufactured by Fuji Photo Film Co., Ltd. The liquid temperature was maintained at 30 ° C., and development was performed for 12 seconds. At this time, it was confirmed whether there was any stain or coloring due to a defective recording layer remaining film, and the conductivity of the developer that was able to be developed satisfactorily was measured.
The results are shown in Table 4 below. A developer having a large difference between the upper limit and the lower limit of the conductivity of a developer capable of forming an image is evaluated as being excellent in development latitude.

[Evaluation of scratch resistance]
The positive recording layer surfaces of the lithographic printing plate precursors 1 to 12 obtained in Examples and Comparative Examples were rubbed 15 times with ablation felt CS5 under a load of 250 g using a rotary ablation tester (manufactured by TOYOSEIKI). did.
Then, using a Fuji Photo Film Co., Ltd. PS processor 940HII charged with a developer DT-2 (DT-2: diluted with water = 1: 8), the solution temperature was 30 degrees. And developed for a development time of 12 s. The electric conductivity of the developer at this time was 45 mS / cm. The scratch resistance was evaluated according to the following criteria. Above Δ is a level with no practical problem. The results are shown in Table 4 below.

<Evaluation criteria for scratch resistance>
○: The optical density of the photosensitive film in the rubbed part was not changed at all. Δ: The optical density of the photosensitive film in the rubbed part was slightly observed visually. ×: The optical density of the photosensitive film in the rubbed part was What became 2/3 or less of the non-friction part

[Sharpness of image]
The lithographic printing plate precursors 1 to 12 obtained in Examples and Comparative Examples were drawn with a test pattern (Staccato 10) at a beam intensity of 9 w and a drum rotation speed of 150 rpm using a Trend setter manufactured by Creo. Fuji Photo Film Co., Ltd. was charged with the lithographic printing plate precursors 1 to 11 exposed under the above-described conditions and a developer DT-2 (DT-2: diluted with water = 1: 8) manufactured by Fuji Photo Film Co., Ltd. ) Using a PS processor 940HII manufactured, the liquid temperature was kept at 30 ° C., and development was performed for 12 seconds.
The edge part of the obtained image was observed with an electron microscope (Hitachi S-800, manufactured by Hitachi, Ltd.). The image sharpness evaluation was performed according to the following criteria. The results are shown in Table 4 below.

<Evaluation criteria for image sharpness>
○: The image has a straight side. Δ: The image has a part of the side that is slightly missing. X: The image has a half of the side.

[Print durability]
The lithographic printing plate precursors 1 to 12 obtained in Examples and Comparative Examples are exposed with the exposure energy (mJ / cm ² ) in the sensitivity evaluation results, and then developed with a developer DT- manufactured by Fuji Photo Film Co., Ltd. 2 (diluted to a conductivity of 43 mS / cm). The lithographic printing plate thus obtained was continuously printed using a printing machine Lithlon manufactured by Komori Corporation. Continuous printing was continued, and how many sheets could be printed with sufficient ink density was measured visually. It is evaluated that the larger the number, the better. The results are shown in Table 4 below.

  As is apparent from Table 4, the lithographic printing plate precursors 1 to 10 of Examples 1 to 10 (lithographic printing plate precursors of the present invention) in which the dispersed phase of the specific modified alkali-soluble resin in the present invention was formed on the lower recording layer Compared with the lithographic printing plate precursors 11 and 12 of Comparative Examples 1 and 2, both have excellent sensitivity, printing durability, and development latitude while maintaining good scratch resistance with no practical problems. It was found that a sharp image can be obtained.

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

Explanation of symbols

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

Claims (1)

A lithographic printing plate precursor comprising a resin and an infrared absorber on a support, and having two or more positive-type recording layers having increased solubility in an alkaline aqueous solution by infrared laser exposure,
Among the two or more positive recording layers, the positive recording layer closest to the support contains at least two resins, at least one of these resins has a phenolic hydroxyl group, and A lithographic printing plate precursor characterized in that a part thereof is an esterified alkali-soluble resin, and a dispersed phase is formed by the alkali-soluble resin.

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