WO2020066377A1

WO2020066377A1 - Lithographic-printing-plate original and lithographic-printing-plate manufacturing method

Info

Publication number: WO2020066377A1
Application number: PCT/JP2019/032690
Authority: WO
Inventors: 敦靖野崎
Original assignee: 富士フイルム株式会社
Priority date: 2018-09-27
Filing date: 2019-08-21
Publication date: 2020-04-02

Abstract

Provided are: a lithographic-printing-plate original that has an image recording layer on a support, wherein the image recording layer contains a polymerization initiator that generates both a radical and an acid, a compound having a radical polymerizable group, a compound having a cation polymerizable group, and an infrared absorber; and a lithographic-printing-plate manufacturing method employing the lithographic-printing-plate original.

Description

Lithographic printing plate precursor and method of preparing lithographic printing plate

(4) The present disclosure relates to a lithographic printing plate precursor and a method for producing a lithographic printing plate.

In general, a lithographic printing plate is composed of an oleophilic image area that receives ink during the printing process and a hydrophilic non-image area that receives fountain solution. Lithographic printing utilizes the property that water and oil-based ink repel each other, so that the lipophilic image area of the lithographic printing plate is an ink receiving area and the hydrophilic non-image area is a dampening water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of a lithographic printing plate, the ink is deposited only on an image portion, and then the ink is transferred to a printing medium such as paper for printing.
Conventionally, in order to produce this lithographic printing plate, a lithographic printing plate precursor (PS plate) comprising a hydrophilic support and a lipophilic photosensitive resin layer (image recording layer) provided thereon is widely used. Usually, after the lithographic printing plate precursor is exposed through an original image such as a lithographic film, the image portion of the image recording layer is left, and other unnecessary image recording layers are washed with an alkaline developer or an organic solvent. A lithographic printing plate is obtained by performing plate making by a method of dissolving and removing with a solvent and exposing the surface of a hydrophilic support to form a non-image portion.

In addition, due to increasing interest in the global environment, environmental issues relating to waste liquids associated with wet processing such as development processing have been highlighted.
In response to the above-mentioned environmental issues, simplification and non-processing of development or plate making are aimed at. As one of the simple manufacturing methods, a method called “on-press development” is performed. That is, after exposure of the lithographic printing plate precursor, conventional development is not carried out, and the lithographic printing plate precursor is directly mounted on a printing machine to remove unnecessary portions of the image recording layer at an initial stage of a normal printing process.

Conventional lithographic printing plate precursors include, for example, those described in Patent Document 1 or Patent Document 2.
U.S. Pat. No. 5,086,097 discloses a support; an initiator system including an onium salt and an infrared (IR) absorber, a polymerizable material, and a polymer binder including a polyethylene oxide segment, coated on the support. And a radiation-sensitive layer comprising:

Patent Document 2 discloses that an on-press development type lithographic printing plate precursor having an image recording layer on a support is image-exposed, and the surface of the image-exposed on-press development type lithographic printing plate precursor contains a water-soluble dye. The plate information is printed with a water-based ink to be printed, and the on-press development type lithographic printing plate precursor on which the plate information is printed is supplied with a neutral to alkaline dampening solution and printing ink on a printing press, and the unexposed portion of the image recording layer is printed. And a printing method for printing.

Patent Document 1: JP-A-2011-51350 Patent Document 2: JP-A-2015-123683

A problem to be solved by the embodiments of the present invention is to provide a lithographic printing plate precursor that can provide a lithographic printing plate excellent in printing durability even when using an ultraviolet curable ink (UV ink).
A problem to be solved by another embodiment of the present invention is to provide a method for producing a lithographic printing plate using the lithographic printing plate precursor.

Means for solving the above problems include the following aspects.
<1> An image recording layer on a support, wherein the image recording layer comprises a polymerization initiator that generates both a radical and an acid, a compound having a radical polymerizable group, and a compound having a cationic polymerizable group. A lithographic printing plate precursor comprising: a lithographic printing plate precursor;
<2> The lithographic printing plate precursor according to <1>, wherein the polymerization initiator is a compound having a salt structure.
<3> The lithographic printing plate precursor according to <2>, wherein the polymerization initiator is a compound having an onium salt structure.
<4> The lithographic printing plate precursor according to <2> or <3>, wherein the pKa of the counter anion having the salt structure in the polymerization initiator is −5 or less.
<5> The compound having a radical polymerizable group includes a binder polymer having a radical polymerizable group, and the compound having a cationic polymerizable group includes a binder polymer having a cationic polymerizable group. <1> to <4 The lithographic printing plate precursor according to any one of <1> to <3>.
<6> The compound according to any one of <1> to <4>, wherein the compound having a radical polymerizable group includes a monomer having a radical polymerizable group, and the compound having a cationic polymerizable group includes a monomer having a cationic polymerizable group. The lithographic printing plate precursor according to any one of the above.
<7> The compound having a radical polymerizable group and the compound having a cationic polymerizable group include particles containing a monomer having a radical polymerizable group and a monomer having a cationic polymerizable group. 4> The lithographic printing plate precursor according to any one of the above.
<8> The compound having a radical polymerizable group includes a binder polymer having a radical polymerizable group and a monomer having a radical polymerizable group, and the compound having a cationic polymerizable group is a binder polymer having a cationic polymerizable group. And the lithographic printing plate precursor according to <5> or <6>, further comprising a monomer having a cationically polymerizable group.
<9> The compound having a radical polymerizable group and the compound having a cationic polymerizable group include a monomer having a radical polymerizable group, a monomer having a cationic polymerizable group, and a monomer having a radical polymerizable group. The lithographic printing plate precursor according to <6> or <7>, comprising particles containing a monomer having a cationically polymerizable group.
<10> The compound having the radical polymerizable group, and the compound having the cationic polymerizable group, a binder polymer having a radical polymerizable group, a monomer having a radical polymerizable group, a binder polymer having a cationic polymerizable group, The lithographic printing plate precursor according to <8> or <9>, comprising a monomer having a cationically polymerizable group, and particles containing a monomer having a radically polymerizable group and a monomer having a cationically polymerizable group.
<11> The lithographic printing plate precursor according to any one of <1> to <10>, which is an on-press development type lithographic printing plate precursor.
<12> a step of imagewise exposing the lithographic printing plate precursor according to any one of <1> to <11> to form an exposed portion and an unexposed portion, and a printing ink and a fountain solution A method for producing a lithographic printing plate, comprising the step of supplying at least one of the above and removing the unexposed portion.

According to the embodiment of the present invention, it is possible to provide a lithographic printing plate precursor from which a lithographic printing plate excellent in printing durability can be obtained even when UV ink is used.
According to another embodiment of the present invention, it is possible to provide a method for producing a lithographic printing plate using the lithographic printing plate precursor.

Hereinafter, the content of the present disclosure will be described in detail. The description of the components described below may be made based on typical embodiments of the present disclosure, but the present disclosure is not limited to such embodiments.
In this specification, “to” indicating a numerical range is used to mean that the numerical values described before and after the numerical range are included as a lower limit and an upper limit.
In the numerical ranges described in stages in this specification, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit of the numerical range described in other stages. Good. Further, in the numerical ranges described in this specification, the upper limit or the lower limit of the numerical ranges may be replaced with the values shown in the embodiments.
Further, in the notation of a group (atomic group) in the present specification, the notation not indicating substituted or unsubstituted includes not only a group having no substituent but also a group having a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
In the present specification, “(meth) acryl” is a term used in a concept including both acryl and methacryl, and “(meth) acryloyl” is a term used as a concept including both acryloyl and methacryloyl. It is.
In addition, the term “step” in the present specification is not limited to an independent step, and even if it cannot be clearly distinguished from other steps, the term is used as long as the intended purpose of the step is achieved. included. In the present disclosure, “mass%” and “wt%” have the same meaning, and “mass part” and “part by weight” have the same meaning.
Furthermore, in the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.
In addition, columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (all trade names manufactured by Tosoh Corporation) are used for the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure unless otherwise specified. It is a molecular weight detected by a gel permeation chromatography (GPC) analyzer using a solvent THF (tetrahydrofuran) and a differential refractometer and converted using polystyrene as a standard substance.
In this specification, the term “lithographic printing plate precursor” includes not only the lithographic printing plate precursor but also a discarded plate precursor. Further, the term "lithographic printing plate" includes not only a lithographic printing plate precursor but also a lithographic printing plate produced through operations such as exposure and development, if necessary, as well as a discarded plate. In the case of a discarded plate master, exposure and development operations are not necessarily required. The discarded plate is a lithographic printing plate precursor to be attached to an unused plate cylinder, for example, when printing a part of the paper surface in a single color or two colors in color newspaper printing.
Hereinafter, the present disclosure will be described in detail.

(Lithographic printing plate precursor)
The lithographic printing plate precursor according to the present disclosure has an image recording layer on a support, and the image recording layer has a polymerization initiator that generates both radicals and acids, a compound having a radical polymerizable group, and a cation. It contains a compound having a polymerizable group and an infrared absorber.
The lithographic printing plate precursor according to the present disclosure can be suitably used as an on-press development type lithographic printing plate precursor.

The inventor of the present invention has found that, in a lithographic printing plate formed using a conventional lithographic printing plate precursor, the printing durability is not sufficient, and in particular, when performing printing using an ultraviolet curable ink (UV ink), Is not enough.
Since the UV ink contains a polymerizable compound, it has a high affinity for the negative type image recording layer. When the UV ink is used as the printing ink, even if the cured negative type image recording layer is used, the UV ink may be used. In some cases, the printing durability was not sufficient due to the penetration of.
Therefore, the present inventor has conducted a detailed study, and by adopting the above-described configuration, a lithographic printing plate having excellent printing durability (hereinafter, also simply referred to as “UV ink printing durability”) even when using UV ink. Was obtained to obtain a lithographic printing plate precursor.
Although the detailed mechanism is not clear, it is estimated as follows.
In the image recording layer, by using a polymerization initiator which is cured by both radical polymerization and cationic polymerization and generates both radicals and acids, radical polymerization occurs in exposed portions (image portions) of the image recording layer. It is presumed that both a polymer chain formed by the polymerization and a polymer chain formed by the cationic polymerization are formed, a strong image portion can be formed, and the UV ink has excellent printing durability.

Hereinafter, details of the lithographic printing plate precursor according to the present disclosure will be described.

<Support>
The support in the lithographic printing plate precursor according to the present disclosure can be appropriately selected from known hydrophilic supports for lithographic printing plate precursors and used. Preferred examples of the support include a hydrophilic support. As the hydrophilic support, an aluminum plate which has been subjected to a surface roughening treatment and anodized by a known method is preferable.
The aluminum plate may be further processed, if necessary, by enlarging or sealing the micropores of the anodic oxide film described in JP-A-2001-253181 and JP-A-2001-322365, US Pat. No. 066, No. 3,181,461, No. 3,280,734 and No. 3,902,734, surface hydrophilization treatment with an alkali metal silicate, U.S.A. The surface hydrophilization treatment with polyvinylphosphonic acid or the like described in each specification of Patent Nos. 3,276,868, 4,153,461 and 4,689,272 is appropriately selected. You may go.
The support preferably has a center line average roughness of 0.10 μm to 1.2 μm.

The support may have an organic polymer compound described in JP-A-5-45885 or a silicon alkoxy compound described in JP-A-6-35174, if necessary, on the surface opposite to the image recording layer. May be included.

<Image recording layer>
The image recording layer in the lithographic printing plate precursor according to the present disclosure, a polymerization initiator that generates both radicals and acids, a compound having a radical polymerizable group, a compound having a cationic polymerizable group, and an infrared absorber Including.
The image recording layer may be a single layer, or may be a multilayer of two or more layers, at least one of the image recording layers, a polymerization initiator that generates both radicals and acids, a radical It is preferable to include a compound having a polymerizable group, a compound having a cationic polymerizable group, and an infrared absorber.
The image recording layer used in the present disclosure is preferably a negative image recording layer, and more preferably a water-soluble or water-dispersible negative image recording layer.
In the lithographic printing plate precursor according to the present disclosure, it is preferable that an unexposed portion of the image recording layer can be removed with at least one of a fountain solution and a printing ink from the viewpoint of on-press developability.

<<< polymerization initiator generating both radical and acid >>
The image recording layer in the lithographic printing plate precursor according to the present disclosure contains a polymerization initiator that generates both radicals and acids (hereinafter, also simply referred to as “polymerization initiator”).
A polymerization initiator that generates both a radical and an acid is a compound that generates both a radical and an acid by the energy of light, heat, or both. The compound is preferably a compound that generates a radical and an acid as a polymerization initiation species by receiving one electron by electron transfer.
The polymerization initiator that generates both radicals and acids is preferably a compound having a salt structure, and particularly preferably a compound having an onium salt structure, from the viewpoints of UV ink printing durability, sensitivity and curability. preferable.
Further, the pKa of the counter anion having the above salt structure in the polymerization initiator generating both radicals and acids is preferably -3 or less, and -5 or less from the viewpoints of UV ink printing durability, sensitivity and curability. Is more preferable, and particularly preferably -20 or more and -5 or less.
The acid dissociation constant pKa in the present disclosure is calculated by the following method. Specifically, the structure of a polymerization initiator that generates both radicals and acids is drawn using chemical structure drawing software “Marvin sketch” (manufactured by Chem Axon), and the acid dissociation constant is calculated.
The polymerization initiator that generates both a radical and an acid is preferably an infrared-sensitive polymerization initiator.
The polymerization initiator that generates both a radical and an acid may be used alone or in combination of two or more.

Among the polymerization initiators that generate both radicals and acids, iodonium salt compounds or sulfonium salt compounds are preferable, and iodonium salt compounds are particularly preferable, from the viewpoint of UV ink printing durability.
Specific examples of these compounds are shown below, but the present disclosure is not limited thereto.

As an example of the iodonium salt compound, a diaryliodonium salt compound is preferable, particularly an electron-donating group, for example, a diphenyliodonium salt compound substituted with an alkyl group or an alkoxy group is more preferable, and an asymmetric diphenyliodonium salt compound is preferable. . As specific examples, diphenyliodonium = hexafluorophosphate, 4-methoxyphenyl-4- (2-methylpropyl) phenyliodonium = hexafluorophosphate, 4- (2-methylpropyl) phenyl-p-tolyliodonium = hexa Fluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium = tetrafluoroborate, 4-octyloxy Phenyl-2,4,6-trimethoxyphenyliodonium = 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, bis ( -t- butylphenyl) iodonium hexafluorophosphate and the like.

As an example of the sulfonium salt compound, a triarylsulfonium salt compound is preferable. As specific examples, triphenylsulfonium = hexafluorophosphate, triphenylsulfonium = benzoylformate, bis (4-chlorophenyl) phenylsulfonium = benzoylformate, bis (4-chlorophenyl) -4-methylphenylsulfonium = tetrafluoro Borate, tris (4-chlorophenyl) sulfonium = 3,5-bis (methoxycarbonyl) benzenesulfonate, tris (4-chlorophenyl) sulfonium = hexafluorophosphate, tris (2,4-dichlorophenyl) sulfonium = hexafluorophos Fart.

Preferable examples of the counter anion of the iodonium salt compound and the sulfonium salt compound include an anion containing at least one atom selected from the group consisting of a boron atom, an antimony atom, and a phosphorus atom from the viewpoint of UV ink printing durability. And BF ₄ ⁻ , tetraaryl borate, SbF ₆ ⁻ , or PF ₆ ⁻ . BF ₄ ⁻ or SbF ₆ ⁻ is particularly preferred.
Further, as a counter anion of the iodonium salt compound and the sulfonium salt compound, a sulfonamide anion or a sulfonimide anion is preferable, and a sulfonimide anion is more preferable.
As the sulfonamide anion, an arylsulfonamide anion is preferable.
As the sulfonimide anion, a bisarylsulfonimide anion is preferable.
The polymerization initiator that generates both a radical and an acid is preferably an onium salt compound containing an anion having a halogen atom from the viewpoints of UV ink printing durability, sensitivity, and curability.
In addition, in the above-mentioned anions having an aromatic ring such as the tetraaryl borate, the arylsulfonamide anion, and the bisarylsulfonimide anion, from the viewpoint of UV ink printing durability, sensitivity and curability, the electron withdrawing property on the aromatic ring is considered. It is preferably an anion having a group.
The electron withdrawing group is not particularly limited, but is preferably a halogen atom, and more preferably a fluorine atom or a chlorine atom.

The content of the polymerization initiator that generates both radicals and acids is preferably from 0.1% by mass to 50% by mass, and more preferably from 0.5% by mass, based on the total mass of the image recording layer from the viewpoint of developability. It is more preferably from 30% by mass to 30% by mass, particularly preferably from 0.8% by mass to 20% by mass.

<< compounds having a radical polymerizable group and compounds having a cationic polymerizable group >>
The image recording layer in the lithographic printing plate precursor according to the present disclosure includes a compound having a radical polymerizable group (also referred to as a “radical polymerizable compound”) and a compound having a cationic polymerizable group (also referred to as a “cationic polymerizable compound”). .).
The compound having a radical polymerizable group and the compound having a cationic polymerizable group may be a monomer, a binder polymer, or a particle.
In the present disclosure, the monomer is a compound having a molecular weight of less than 2,000, and the polymer (binder polymer) is a compound having a molecular weight (weight average molecular weight Mw) of 2,000 or more. When the compound has a molecular weight distribution, the molecular weight is preferably represented by a weight average molecular weight.
From the viewpoint of UV ink printing durability, the molecular weight of the monomer having a radical polymerizable group and the monomer having a cationic polymerizable group is preferably 100 or more and less than 2,000, and is 200 or more and 1,800 or less. Is more preferable.
The weight average molecular weight Mw of the binder polymer having a radical polymerizable group and the binder polymer having a cationic polymerizable group is preferably 5,000 or more from the viewpoint of UV ink printing durability, and is preferably 10,000 to 300. 2,000, more preferably 25,000 to 100,000.
The compound having a radical polymerizable group may be used alone or in combination of two or more. However, from the viewpoint of the printing durability of UV ink, it is preferable to contain three or more kinds. It is more preferred to contain from 5 to 5 species.
The compound having a cationically polymerizable group may be used alone or in combination of two or more. However, from the viewpoint of UV ink printing durability, it is preferable to contain three or more, preferably 3 or more. It is more preferred to contain from 5 to 5 species.

As the particles, particles having a radical polymerizable group, particles having a cationic polymerizable group, particles having a radical polymerizable group and a cationic polymerizable group, particles containing a monomer having a radical polymerizable group, having a cationic polymerizable group Preferable examples include particles containing a monomer, particles containing a monomer having a radical polymerizable group and a monomer having a cationic polymerizable group. Among them, the image recording layer is, from the viewpoint of UV ink printing durability, particles containing a monomer having a radical polymerizable group, particles containing a monomer having a cationic polymerizable group, and a monomer having a radical polymerizable group and a cationic It is preferable to include at least one kind of particle selected from the group consisting of particles including a monomer having a polymerizable group, and to include particles including a monomer having a radical polymerizable group and a monomer having a cationic polymerizable group. Is more preferred.

The radical polymerizable group in the compound having a radical polymerizable group is preferably an ethylenically unsaturated group from the viewpoint of UV ink printing durability, sensitivity, and curability, and is preferably a (meth) acryl group or a styryl group. Is preferable, a (meth) acryl group is more preferable, and a (meth) acryloxy group is particularly preferable.
The “styryl group” in the present disclosure may be any group in which a vinyl group is directly bonded to an aromatic ring of an aryl group, and is preferably a vinylphenyl group.
The cationically polymerizable group in the compound having a cationically polymerizable group is preferably a cyclic ether group, a cyclic imino ether group, or an ethylenically unsaturated group from the viewpoint of UV ink printing durability, sensitivity, and curability. , An epoxy group, an oxetanyl group, an allyl group, a vinyl ether group, or a vinyloxycarbonyl group, preferably an epoxy group, an oxetanyl group, an allyl group, or a vinyl ether group, more preferably an epoxy group, an allyl group Or a vinyl ether group is more preferable, and a vinyl ether group is particularly preferable.
Further, as the cationically polymerizable group in the compound having a cationically polymerizable group, an ethylenically unsaturated group is preferable, an allyl group, or a vinyl ether group is more preferable, from the viewpoint of on-press developability and aging on-press developability, Vinyl ether groups are particularly preferred.

The compound having a radically polymerizable group preferably contains a binder polymer having a radically polymerizable group from the viewpoints of UV ink printing durability and on-press developability.
Further, it is preferable that the compound having a cationically polymerizable group contains a binder polymer having a cationically polymerizable group from the viewpoints of printing durability and on-press developability of UV ink.
Further, from the viewpoint of UV ink printing durability and on-press developability, the image recording layer has a compound having the radical polymerizable group, and a binder having the radical polymerizable group as the compound having the cationic polymerizable group. It is more preferable to include a polymer and a binder polymer having a cationically polymerizable group.

The compound having a radical polymerizable group preferably contains a monomer having a radical polymerizable group from the viewpoint of printing durability and curability of the UV ink.
Further, it is preferable that the compound having a cationically polymerizable group contains a monomer having a cationically polymerizable group from the viewpoints of printing durability and curability of UV ink.
Further, the image recording layer, from the viewpoint of UV ink printing durability and curability, a compound having a radical polymerizable group, and a monomer having a radical polymerizable group as the compound having a cationic polymerizable group, and And a monomer having a cationically polymerizable group.

In the image recording layer, the compound having a radical polymerizable group has a binder polymer having a radical polymerizable group and a radical polymerizable group from the viewpoint of UV ink printing durability, on-press developability, and curability. It is preferable to include a monomer, and it is preferable that the compound having a cationically polymerizable group include a binder polymer having a cationically polymerizable group and a monomer having a cationically polymerizable group.
Above all, the image recording layer is formed from a UV ink printing durability, an on-press developability, and a curable viewpoint, in which the compound having the radical polymerizable group is a binder polymer having a radical polymerizable group and a radical polymerizable group. More preferably, the compound having a cationically polymerizable group contains a binder polymer having a cationically polymerizable group and a monomer having a cationically polymerizable group.

The image recording layer, UV ink printing durability, on-press developability, on-press developability over time, and, from the viewpoint of curability, a monomer having a radical polymerizable group, a monomer having a cationic polymerizable group, and a radical It is preferable to include particles containing a monomer having a polymerizable group and a monomer having a cationic polymerizable group, a binder polymer having a radical polymerizable group, a monomer having a radical polymerizable group, a binder polymer having a cationic polymerizable group, It is particularly preferable to include a monomer having a cationically polymerizable group, and particles containing a monomer having a radically polymerizable group and a monomer having a cationically polymerizable group.

The content of the compound having a radical polymerizable group is preferably 5% by mass to 70% by mass with respect to the total mass of the image recording layer, from the viewpoints of UV ink printing durability and on-press developability. The content is more preferably from 65% by mass to 65% by mass, and particularly preferably from 15% by mass to 55% by mass.
The content of the compound having a cationically polymerizable group is preferably 2% by mass to 70% by mass with respect to the total mass of the image recording layer, from the viewpoints of UV ink printing durability and on-press developability. It is more preferably from 60% by mass to 60% by mass, and particularly preferably from 10% by mass to 50% by mass.

Further, the total content of the compound having a radical polymerizable group and the compound having a cationic polymerizable group is 5% by mass based on the total mass of the image recording layer from the viewpoint of UV ink printing durability and on-press developability. It is preferably from 75% by mass, more preferably from 10% by mass to 70% by mass, particularly preferably from 15% by mass to 60% by mass.
Further, in the image recording layer, and the content of M _R of the compound having a radical polymerizable group, the value of the mass ratio of the content M _C of the compound having a cationically polymerizable group _{_{(M R / M C),}} UV From the viewpoints of ink printing durability and on-press developability, it is preferably 0.2 or more and 5 or less, more preferably 0.5 or more and 4 or less, and still more preferably 1 or more and 3.5 or less. , 1.5 or more and 3 or less.
Further, from the viewpoint of UV ink printing durability and on-press developability, the content of the compound having a radical polymerizable group in the image recording layer is more than the content of the compound having a cationic polymerizable group in the image recording layer. Preferably, it is large.

-Monomer having radical polymerizable group-
The monomer having a radical polymerizable group used in the present disclosure may be a monofunctional monomer or a polyfunctional monomer, but is preferably a polyfunctional monomer from the viewpoint of UV ink printing durability.
The monomer having a radical polymerizable group preferably contains a monomer having 2 to 20 radical polymerizable groups from the viewpoint of UV ink printing durability, and a monomer having 3 to 12 radical polymerizable groups. And more preferably a monomer having 3 to 10 radically polymerizable groups.
Further, the monomer having a radical polymerizable group is, from the viewpoint of UV ink printing durability and on-press developability, an isocyanuric ring, a pentaerythritol skeleton, a dipentaerythritol skeleton, a trimethylolpropane skeleton, a ditrimethylolpropane skeleton, and a trimethylolpropane skeleton. It is preferable to include a monomer having a radical polymerizable group having at least one structure selected from the group consisting of a methylolethane skeleton and a ditrimethylolethane skeleton, and an isocyanuric ring, a pentaerythritol skeleton, and a dipentaerythritol skeleton It is more preferable to include a monomer having a radical polymerizable group having at least one kind of structure selected from the group consisting of:

As the monomer having a radical polymerizable group, a polyfunctional ethylenically unsaturated compound is preferably exemplified, and a polyfunctional (meth) acrylate compound and a polyfunctional (meth) acrylamide compound are more preferably exemplified. Acrylate compounds are particularly preferred.
As the polyfunctional (meth) acrylate compound, an ester monomer of a polyhydric alcohol compound and an unsaturated carboxylic acid is preferably exemplified.
Specific examples of the monomer of the ester of the polyhydric alcohol compound and the unsaturated carboxylic acid include, as acrylates, ethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, Examples include trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, isocyanuric acid ethylene oxide (EO) -modified triacrylate, and polyester acrylate oligomer. As methacrylic acid esters, tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis [p- (3-methacryloxy-2-hydroxypropoxy) phenyl] Dimethylmethane, bis [p- (methacryloxyethoxy) phenyl] dimethylmethane, tris (acryloyloxyethyl) isocyanurate and the like can be mentioned.
Specific examples of the amide monomer of a polyfunctional amine compound which is a polyfunctional (meth) acrylamide compound and an unsaturated carboxylic acid include methylenebisacrylamide, methylenebismethacrylamide, 1,6-hexamethylenebisacrylamide, , 6-hexamethylenebismethacrylamide, diethylenetriaminetrisacrylamide, xylylenebisacrylamide, xylylenebismethacrylamide, and the like.

The monomer having a radical polymerizable group may contain one kind alone or two or more kinds.
The content of the monomer having a radical polymerizable group is preferably from 2% by mass to 70% by mass, and more preferably from 3% by mass, based on the total mass of the image recording layer, from the viewpoints of UV ink printing durability and curability. It is more preferably from 65 to 65% by mass, particularly preferably from 10 to 55% by mass.
Further, the content of the monomer having a radical polymerizable group in the image recording layer is larger than the content of the binder polymer having the radical polymerizable group from the viewpoint of UV ink printing durability, on-press developability and curability. Is preferred.

-Binder polymer having radical polymerizable group-
The binder polymer having a radical polymerizable group may be any polymer having a radical polymerizable group, but from the viewpoint of UV ink printing durability and on-press developability, an acrylic resin, a polyvinyl acetal resin, or a polyurethane. Resins are preferred, and acrylic resins are particularly preferred.
The binder polymer having a radical polymerizable group is preferably a binder polymer used for an on-press development type lithographic printing plate precursor.
As the binder polymer for on-press development, a binder polymer having an alkylene oxide chain is preferable. The binder polymer having an alkylene oxide chain may have a poly (alkylene oxide) site in the main chain or a side chain. Further, a graft polymer having poly (alkylene oxide) in the side chain or a block copolymer of a block composed of poly (alkylene oxide) -containing repeating units and a block composed of (alkylene oxide) -free repeating units may be used.
When a poly (alkylene oxide) moiety is present in the main chain, a polyurethane resin is preferred. Examples of the main chain polymer having a poly (alkylene oxide) moiety in the side chain include acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, novolac phenol resin, Examples include polyester resin, synthetic rubber, and natural rubber, and acrylic resin is particularly preferable.

Further, as another preferable example of the binder polymer having a radical polymerizable group, a polyfunctional thiol having 6 to 10 functional groups as a nucleus has a polymer chain bonded to the nucleus by a sulfide bond. A polymer compound having a radical polymerizable group (hereinafter, also referred to as a star-shaped polymer compound) may be used. As the star polymer compound, for example, compounds described in JP-A-2012-148555 can be preferably used.

The star-shaped polymer compound has a radical polymerizable group such as an ethylenically unsaturated bond for improving the film strength of an image portion as described in JP-A-2008-195018, and has a main chain or a side chain, preferably What has in a side chain is mentioned. Crosslinks are formed between polymer molecules by the radical polymerizable group, and curing is promoted.
As the radical polymerizable group, a (meth) acryl group, a vinyl group, an allyl group, an ethylenically unsaturated group such as a styryl group and the like are preferable, and a (meth) acryl group and a styryl group are more preferable in terms of polymerization reactivity. (Meth) acryl groups are more preferred, and (meth) acryloxy groups are particularly preferred. These groups can be introduced into the polymer by a polymer reaction or copolymerization. For example, a reaction between a polymer having a carboxy group in a side chain and glycidyl methacrylate, or a reaction between a polymer having an epoxy group and a carboxylic acid having an ethylenically unsaturated group such as methacrylic acid can be used. These groups may be used in combination.

Further, the binder polymer having a radical polymerizable group has a structure represented by any of the following formulas (B-1) to (B-5) from the viewpoint of UV ink printing durability and on-press developability. And more preferably a structure represented by the following formula (B-3).

In Formulas (B-1) to (B-5), W ¹ to W ³ each independently represent an alkyl group having 1 to 6 carbon atoms, and a wavy line represents a bonding position with another structure.

The binder polymer having a radical polymerizable group may contain one kind alone, or may contain two or more kinds.
The content of the binder polymer having a radical polymerizable group is preferably from 2% by mass to 70% by mass, and more preferably from 3% by mass with respect to the total mass of the image recording layer, from the viewpoints of UV ink printing durability and curability. % To 60% by mass, more preferably 5% to 50% by mass.

-Monomer having cationically polymerizable group-
Examples of the monomer having a cationic polymerizable group include a compound having an oxiranyl group (also referred to as an “epoxy group”) (also referred to as an “oxirane compound” or an “epoxy compound”) and a compound having an oxetanyl group (also referred to as an “oxetane compound”). ), Known cation polymerization compounds such as allyl compounds, oxazoline compounds, vinyl ether compounds, and vinyl ester compounds can be used without any particular limitation.
Among them, UV ink printing durability, and, from the viewpoint of curability, a compound having an epoxy group, a compound having an oxetanyl group, a compound having an allyl group, a compound having an oxazoline ring structure, or a compound having a vinyl ether group. The compound is preferably a compound having an epoxy group, a compound having an allyl group, or a compound having a vinyl ether group, and particularly preferably a compound having a vinyl ether group.
The monomer having a cationically polymerizable group preferably contains a monomer having 2 to 20 cationically polymerizable groups from the viewpoint of UV ink printing durability, and preferably has a monomer having 2 to 12 cationically polymerizable groups. And more preferably a monomer having 3 to 6 cationically polymerizable groups.

Further, from the viewpoints of UV ink printing durability and on-press developability, monomers having a cationic polymerizable group include an isocyanuric ring, a pyromellitic acid skeleton, a pentaerythritol skeleton, a dipentaerythritol skeleton, a trimethylolpropane skeleton, and a dimethylolpropane skeleton. Methylol propane skeleton, trimethylol ethane skeleton, and preferably contains a monomer having at least one structure selected from the group consisting of a ditrimethylol ethane skeleton and a cationic polymerizable group, isocyanuric ring, pyromellitic acid skeleton, It is more preferable to include a monomer having at least one structure selected from the group consisting of a pentaerythritol skeleton and a dipentaerythritol skeleton and a cationic polymerizable group, and an isocyanuric ring or a pyromellitic acid skeleton and cationic polymerization Having a functional group It is particularly preferred, including over.

Examples of the monomer having a cationic polymerizable group include, for example, JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, and JP-A-2001-310937. Epoxy compounds, vinyl ether compounds, oxetane compounds, and the like described in each gazette such as JP-A-2001-220526.

Examples of the epoxy compound include an aromatic epoxide, an alicyclic epoxide, and an aliphatic epoxide.
Examples of the aromatic epoxide include di- or polyglycidyl ether of bisphenol A or an alkylene oxide adduct thereof, hydrogenated bisphenol A or a di- or polyglycidyl ether of an alkylene oxide adduct thereof, and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.
As the alicyclic epoxide, cyclohexene obtained by epoxidizing a compound having at least one cycloalkane ring such as a cyclohexene ring or a cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid is used. Oxides or cyclopentene oxide-containing compounds are preferred.
Examples of the aliphatic epoxide include di- or polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. Typical examples thereof include diglycidyl ethers of ethylene glycol, diglycidyl ether of propylene glycol and diglycidyl ether of 1,6-hexanediol, and the like or diglycidyl ethers of glycerin or alkylene oxide adduct thereof. Polyglycidyl ether of polyhydric alcohols such as glycidyl ether, diglycidyl ether of polyethylene glycol or its alkylene oxide adduct, diglycidyl ether of polyalkylene glycol represented by polypropylene glycol or the diglycidyl ether of its alkylene oxide adduct, etc. No. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.
Further, as the epoxy compound, a compound having an isocyanuric ring such as triglycidyl isocyanurate is preferably exemplified.

The oxetane compound may be any compound having an oxetanyl group. For example, oxetane compounds described in JP-A-2001-220526, JP-A-2001-310937, and JP-A-2003-341217 can be used. .
Examples of the compound having 1 to 4 oxetane rings in the molecule include compounds represented by general formulas (1) to (4) described in paragraphs 0037 to 0051 of JP-A-2007-91946. Can be

As the allyl compound, a known allyl compound can be used.
Specific examples of the allyl compound include triallyl isocyanurate, diallyl phthalate, triallyl trimellitate, diethylene glycol bisallyl carbonate, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol triallyl ether, and pentaerythritol tetraallyl ether. 1,1,2,2-tetraallyloxyethane, diarylidenepentaerythritol, triallyl cyanurate, 1,2,4-trivinylcyclohexane, 1,4-butanediol diallyl ether, nonanediol diallyl ether, 1,4-cyclohexanedimethanol diallyl ether, triethylene glycol diallyl ether, trimethylolpropane trivinyl ether, pentaerythritol Tetravinyl ether, diallyl ether of bisphenol S, divinylbenzene, divinylbiphenyl, 1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, 1,3-bis (allyloxy) adamantane, 1,3-bis ( Vinyloxy) adamantane, 1,3,5-tris (allyloxy) adamantane, 1,3,5-tris (vinyloxy) adamantane, dicyclopentadiene, vinylcyclohexene, 1,5-hexadiene, 1,9-decadiene, diallyl ether , Bisphenol A diallyl ether, 2,5-diallylphenol allyl ether and the like.

Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexane dimethanol divinyl ether, and Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n- B pills vinyl ether, isopropyl vinyl ether, isopropenyl vinyl ether, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

Further, the monomer having a cationically polymerizable group preferably contains a compound represented by the following formula (C-1) or (C-2) from the viewpoints of UV printing durability and on-press developability. .

In Formula C-1 and Formula C-2, R ^C independently represents a group having a cationically polymerizable group.

The number of cationic polymerizable groups in ^RC may be one or more, but is preferably 1 to 6, more preferably 1 to 3, and particularly preferably 1. preferable.
The cationically polymerizable group in ^RC is preferably an epoxy group, an allyl group, or a vinyl ether group, and more preferably a vinyl ether group.
R ^C preferably has 2 to 30 carbon atoms, more preferably 3 to 20 carbon atoms.
Further, -R ^C ^is preferably a -L C ^{-R Ca.}
L ^C represents a single bond or a divalent linking group, and R ^Ca represents a cationically polymerizable group.
L ^C is a single bond, an alkylene group, or an alkylene group, preferably 2 or more divalent formed by combining the structures of the groups selected from the group consisting of an ether bond and an ester bond, an alkylene group, or , An alkylene group, a divalent group formed by bonding two or more structures selected from the group consisting of an ether bond and an ester bond, more preferably a divalent group selected from the group consisting of an alkylene group, an ether bond and an ester bond. In particular, a divalent group formed by combining two or more structures is particularly preferable. The alkylene group is preferably an alkylene group having 2 to 8 carbon atoms. The alkylene group may be linear, branched, or have a ring structure, but is preferably a linear alkylene group.
Further, R ^C in Formula C-1 or Formula C-2 is preferably the same group.

The monomer having a cationically polymerizable group may contain one kind alone, or may contain two or more kinds.
The content of the monomer having a cationically polymerizable group is preferably from 2% by mass to 70% by mass, and more preferably from 3% by mass, based on the total mass of the image recording layer, from the viewpoint of UV ink printing durability and curability. It is more preferably from 65 to 65% by mass, particularly preferably from 10 to 55% by mass.
Further, the content of the monomer having a cationically polymerizable group in the image recording layer is larger than the content of the binder polymer having a cationically polymerizable group from the viewpoints of UV ink printing durability, on-press developability, and curability. Is preferred.

-Binder polymer having cationically polymerizable group-
The binder polymer having a cationically polymerizable group may be any one having a cationically polymerizable group, but from the viewpoint of UV ink printing durability and on-press developability, an acrylic resin, a polyvinyl acetal resin, or a polyurethane. Resins are preferred, and acrylic resins are particularly preferred.
Further, the binder polymer having a cationic polymerizable group is preferably a binder polymer used for an on-press development type lithographic printing plate precursor.
As the binder polymer for on-press development, a binder polymer having an alkylene oxide chain is preferable. The binder polymer having an alkylene oxide chain may have a poly (alkylene oxide) site in the main chain or a side chain. Further, a graft polymer having poly (alkylene oxide) in the side chain or a block copolymer of a block composed of poly (alkylene oxide) -containing repeating units and a block composed of (alkylene oxide) -free repeating units may be used.
When a poly (alkylene oxide) moiety is present in the main chain, a polyurethane resin is preferred. Examples of the main chain polymer having a poly (alkylene oxide) moiety in the side chain include acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, polystyrene resin, novolac phenol resin, Examples include polyester resin, synthetic rubber, and natural rubber, and acrylic resin is particularly preferable.

Further, as another preferable example of the binder polymer having a cationically polymerizable group, a polyfunctional thiol having 6 to 10 functional groups as a nucleus has a polymer chain bonded to the nucleus by a sulfide bond. A polymer compound having a cationically polymerizable group (hereinafter, also referred to as a star-shaped polymer compound) may be used. As the star polymer compound, for example, compounds described in JP-A-2012-148555 can be preferably used.

The star-shaped polymer compound has a cationically polymerizable group such as an ethylenically unsaturated bond for improving the film strength of an image area as described in JP-A-2008-195018, and has a main chain or a side chain, preferably What has in a side chain is mentioned. Crosslinks are formed between polymer molecules by the cationically polymerizable group, and curing is promoted.
From the viewpoint of polymerization reactivity, the cationically polymerizable group is preferably an epoxy group, an allyl group, or a vinyl ether group, and particularly preferably a vinyl ether group. These groups can be introduced into the polymer by a polymer reaction or copolymerization. These groups may be used in combination.

The binder polymer having a cationically polymerizable group has a structure represented by any one of the above formulas (B-1) to (B-5) from the viewpoints of UV ink printing durability and on-press developability. And more preferably a structure represented by the above formula (B-3).

The binder polymer having a cationically polymerizable group may contain one kind alone or two or more kinds.
The content of the binder polymer having a cationic polymerizable group is preferably 2% by mass to 70% by mass, and more preferably 3% by mass, based on the total mass of the image recording layer, from the viewpoints of UV ink printing durability and curability. % To 60% by mass, more preferably 5% to 50% by mass.

-particle-
The particles are preferably polymer particles.
The polymer particles are particles containing a monomer having a radically polymerizable group and a monomer having a cationically polymerizable group from the viewpoints of UV ink printing durability, on-press developability, and on-press developability over time. Preferably, there is.
Further, the polymer particles are preferably thermoplastic polymer particles.
Further, as a method for producing particles containing a compound having a radical polymerizable group or a cationic polymerizable group, a method for producing microcapsules and microgels described later can be referred to. For example, an O / W emulsion may be used. Examples of the method for producing a shell using such a method include a method in which the oil phase contains the compound having a radical polymerizable group or a cationic polymerizable group.

As the thermoplastic polymer particles, Research Disclosure No. 1 of January 1992 can be used. Thermoplastic polymer particles described in JP-A-33303, JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250 and European Patent No. 931647 are preferred.
Specific examples of the polymer constituting the thermoplastic polymer particles include ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, and a polyalkylene structure. Mention may be made of homopolymers or copolymers of monomers such as acrylates or methacrylates or mixtures thereof. Preferably, a copolymer containing polystyrene, styrene and acrylonitrile, or polymethyl methacrylate can be used. The average particle size of the thermoplastic polymer particles is preferably from 0.01 μm to 3.0 μm.

Examples of the heat-reactive polymer particles include polymer particles having a heat-reactive group. The heat-reactive polymer particles form a hydrophobic region by cross-linking due to a heat reaction and a change in a functional group at that time.

The heat-reactive group in the polymer particles having a heat-reactive group may be any functional group that performs any reaction as long as a chemical bond is formed, but is preferably a polymerizable group. An ethylenically unsaturated group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.), a cationically polymerizable group (for example, vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.) for performing radical polymerization reaction, addition reaction Isocyanate group or a block thereof, an epoxy group, a vinyloxy group and a functional group having an active hydrogen atom which is a reaction partner thereof (for example, an amino group, a hydroxy group, a carboxy group, etc.), a carboxy group for performing a condensation reaction and A hydroxy or amino group as a reaction partner, an acid anhydride for performing a ring-opening addition reaction, and an amino acid as a reaction partner. And a group or hydroxy group are preferably exemplified.

(4) The microcapsules are obtained by encapsulating at least a part of the components of the image recording layer in microcapsules as described in JP-A-2001-277740 and JP-A-2001-277742. The components of the image recording layer can be contained outside the microcapsules. In a preferred embodiment, the image recording layer containing microcapsules has a structure in which hydrophobic constituents are encapsulated in microcapsules and hydrophilic constituents are contained outside the microcapsules.

The microgel (crosslinked polymer particles) can contain a part of the constituent components of the image recording layer on at least one of the surface and the inside. In particular, a reactive microgel having a radical polymerizable group on its surface is preferable from the viewpoint of the sensitivity of the resulting lithographic printing plate precursor and the printing durability of the resulting lithographic printing plate.

A known method can be applied to microencapsulate or microgel the components of the image forming layer, such as a compound having a radical polymerizable group and a compound having a cationic polymerizable group.

Further, as the polymer particles, from the viewpoints of UV ink printing durability, stain resistance and storage stability, a polyvalent compound which is an adduct of a polyhydric phenol compound having two or more hydroxy groups in a molecule and isophorone diisocyanate is used. Those obtained by the reaction of an isocyanate compound and a compound having active hydrogen are preferred.
As the polyhydric phenol compound, a compound having a plurality of benzene rings having a phenolic hydroxy group is preferable.
As the compound having the compound having active hydrogen, a polyol compound or a polyamine compound is preferable, a polyol compound is more preferable, and at least one compound selected from the group consisting of propylene glycol, glycerin and trimethylolpropane is further preferable. preferable.
Examples of the resin particles obtained by the reaction of a polyvalent isocyanate compound which is an adduct of a polyhydric phenol compound having two or more hydroxy groups in the molecule with isophorone diisocyanate and a compound having active hydrogen include JP 2012 Preferred are polymer particles described in paragraphs 0032 to 0095 of JP-A-206495.

Further, as the polymer particles, from the viewpoint of UV ink printing durability and solvent resistance, a structural unit having a hydrophobic main chain and i) a pendant cyano group directly bonded to the hydrophobic main chain, And ii) it preferably contains both constituent units having a pendant group containing a hydrophilic polyalkylene oxide segment.
The hydrophobic main chain is preferably an acrylic resin chain.
Preferred examples of the pendant cyano group include-[CH ₂ CH (C≡N)-] or-[CH ₂ C (CH ₃ ) (C≡N)-].
Further, the constituent unit having a pendant cyano group can be easily derived from an ethylenically unsaturated monomer such as acrylonitrile or methacrylonitrile, or a combination thereof.
As the alkylene oxide in the hydrophilic polyalkylene oxide segment, ethylene oxide or propylene oxide is preferable, and ethylene oxide is more preferable.
The number of repeating alkylene oxide structures in the hydrophilic polyalkylene oxide segment is preferably from 10 to 100, more preferably from 25 to 75, and further preferably from 40 to 50.
Both a structural unit having a hydrophobic main chain and i) a pendant cyano group directly bonded to the hydrophobic main chain, and ii) a structural unit having a pendant group containing a hydrophilic polyalkylene oxide segment Preferred examples of the resin particles containing are those described in paragraphs 0039 to 0068 of JP-T-2008-503365.

The average particle size of the particles is preferably 0.01 μm to 3.0 μm, more preferably 0.03 μm to 2.0 μm, and even more preferably 0.10 μm to 1.0 μm. In this range, good resolution and stability over time can be obtained.
The average primary particle size of each of the particles in the present disclosure is measured by a light scattering method, or an electron micrograph of the particles is taken, and the total particle size of the particles is measured on the photograph to be 5,000. The value shall be calculated. In addition, as for the non-spherical particles, the particle diameter value of the spherical particles having the same particle area as the particle area on the photograph is defined as the particle diameter.
Further, the average particle size in the present disclosure is a volume average particle size unless otherwise specified.
The particles may contain one kind alone or two or more kinds.
The particles may contain one compound having a radical polymerizable group alone or may contain two or more compounds. The same applies to compounds having a cationically polymerizable group.
From the viewpoint of developability, the content of the particles is preferably from 5% by mass to 90% by mass based on the total mass of the image recording layer.

<< Infrared absorber >>
The image recording layer contains an infrared absorbing agent.
Infrared absorbers include pigments and dyes.
As the dye used as the infrared absorbing agent, commercially available dyes and known dyes described in literatures such as “Dye Handbook” (edited by the Society of Synthetic Organic Chemistry, Japan, 1970) can be used. Specifically, dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, and metal thiolate complexes Is mentioned.
Preferred examples of these dyes include cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are more preferable. Among them, cyanine dyes are particularly preferred.

Specific examples of the cyanine dye include the compounds described in paragraphs 0017 to 0019 of JP-A-2001-133969, paragraphs 0016 to 0021 of JP-A-2002-023360, and paragraphs 0012 to 0037 of JP-A-2002-040638. The compounds described in paragraphs 0034 to 0041 of JP-A-2002-278057, and the compounds described in paragraphs 0080 to 008 of JP-A-2008-195018, particularly preferably paragraph 0035 of JP-A-2007-90850 are preferred. And the compounds described in paragraphs 0105 to 0113 of JP-A-2012-206495.
Further, compounds described in paragraphs 0008 to 0009 of JP-A-5-5005 and paragraphs 0022 to 0025 of JP-A-2001-222101 can also be preferably used.
As the pigment, compounds described in paragraphs 0072 to 0076 of JP-A-2008-195018 are preferable.

One infrared absorber may be used alone, or two or more infrared absorbers may be used in combination. Further, a pigment and a dye may be used in combination as an infrared absorber.
From the viewpoint of developability, the content of the infrared absorbent is preferably from 0.1% by mass to 10.0% by mass, more preferably from 0.5% by mass to 5.0% by mass, based on the total mass of the image recording layer. preferable.

<< Radical generation assistant >>
The image recording layer preferably contains a radical generation aid from the viewpoints of printing durability and curability of the UV ink.
The radical generation auxiliary in the present disclosure, when the electrons of the infrared absorber are excited or moved intramolecularly by infrared exposure, one electron orbit of the infrared absorber or one electron by intermolecular electron transfer to the polymerization initiator. It is a compound that, when donated, promotes the generation of polymerization initiation species such as radicals.
Preferred examples of the radical generation aid include the following five types.
(I) Alkyl or arylate complex: It is considered that the carbon-hetero bond is oxidatively cleaved to generate an active radical. Specifically, borate compounds are preferred.
(Ii) N-arylalkylamine compound: It is considered that the CX bond on carbon adjacent to nitrogen is cleaved by oxidation to generate an active radical. X is preferably a hydrogen atom, a carboxy group, a trimethylsilyl group or a benzyl group. Specifically, for example, N-phenylglycines (which may or may not have a substituent on the phenyl group), N-phenyliminodiacetic acid (with or without a substituent on the phenyl group) May be used.).
(Iii) Sulfur-containing compound: The above-mentioned amines in which a nitrogen atom is replaced with a sulfur atom can generate an active radical by the same action. For example, phenylthioacetic acid (which may or may not have a substituent on the phenyl group) can be mentioned.
(Iv) Tin-containing compound: The above-mentioned amines in which a nitrogen atom is replaced with a tin atom can generate an active radical by the same action.
(V) Sulfinates: Active radicals can be generated by oxidation. Specific examples include sodium arylsulfinate and the like.

Among these, the image recording layer preferably contains a borate compound from the viewpoints of printing durability and coloring.
The borate compound is preferably a tetraaryl borate compound or a monoalkyltriaryl borate compound, and more preferably a tetraaryl borate compound, from the viewpoint of printing durability and color development.
The counter cation of the borate compound is not particularly limited, but is preferably an alkali metal ion or a tetraalkylammonium ion, and more preferably a sodium ion, a potassium ion, or a tetrabutylammonium ion.

Specific examples of the borate compound include sodium tetraphenyl borate.

好ましい B-1 to B-9 are shown below as preferred specific examples of the radical generation aid, but needless to say, the invention is not limited thereto. In the following chemical formula, Ph represents a phenyl group, and Bu represents an n-butyl group.

As the radical generation aid, only one kind may be added, or two or more kinds may be used in combination.
From the viewpoint of developability, the content of the radical generation aid is preferably 0.01% by mass to 30% by mass, and more preferably 0.05% by mass to 25% by mass, based on the total mass of the image recording layer. More preferably, the content is more preferably 0.1% by mass to 20% by mass.
Further, from the viewpoint of developability, the content ratio by mass of the infrared absorbent and the radical generation auxiliary in the image recording layer is preferably from infrared absorbent: radical generation auxiliary = 10: 1 to 1:10, The ratio is more preferably from 5: 1 to 1: 5, further preferably from 2: 1 to 1: 2, and particularly preferably from 1.5: 1 to 1: 1.5.

<< Acid Coloring Agent >>
The image recording layer preferably contains an acid coloring agent.
The “acid color former” used in the present disclosure means a compound having a property of developing a color when heated while receiving an electron-accepting compound (for example, a proton such as an acid generated from the polymerization initiator). I do. As the acid coloring agent, in particular, it has a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, amide, etc. Compounds are preferred.

Examples of such acid color formers include 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (referred to as “crystal violet lactone”), 3,3-bis (4- Dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) -3- (4-diethylamino-2-methylphenyl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1 , 2-Dimethylindol-3-yl) phthalide, 3- (4-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3) -Yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bi (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1-methylpyrrol-3-yl) -6-dimethylaminophthalide,

3,3-bis [1,1-bis (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1,1-bis ( 4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3,3-bis [1- (4-dimethylaminophenyl) -1- (4-methoxyphenyl) Ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-pyrrolidinophenyl) -1- (4-methoxyphenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3- [1,1-di (1-ethyl-2-methylindol-3-yl) ethylene-2-yl] -3- (4-diethylaminophenyl ) Phthalide, 3- [1,1-di (1-ethyl-2-me Ruindol-3-yl) ethylene-2-yl] -3- (4-N-ethyl-N-phenylaminophenyl) phthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-n -Octyl-2-methylindol-3-yl) -phthalide, 3,3-bis (1-n-octyl-2-methylindol-3-yl) -phthalide, 3- (2-methyl-4-diethylaminophenyl) Phthalides such as) -3- (1-n-octyl-2-methylindol-3-yl) -phthalide;

4,4-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, rhodamine-B-anilinolalactam, rhodamine- (4-nitroanilino ) Lactam, rhodamine-B- (4-chloroanilino) lactam, 3,7-bis (diethylamino) -10-benzoylphenoxazine, benzoylleucomethylene blue, 4-nitrobenzoylmethylene blue,

3,6-dimethoxyfluoran, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-7-chlorofluoran, 3 -Diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6,7-dimethylfluoran, 3-N-cyclohexyl-Nn-butylamino-7-methylfluoran, 3-diethylamino-7- Dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-di-n-hexylaminofluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-7- ( 2'-fluorophenylamino) fluoran, 3-diethylamino 7- (2'-chlorophenylamino) fluoran, 3-diethylamino-7- (3'-chlorophenylamino) fluoran, 3-diethylamino-7- (2 ', 3'-dichlorophenylamino) fluoran, 3-diethylamino-7- (3′-trifluoromethylphenylamino) fluoran, 3-di-n-butylamino-7- (2′-fluorophenylamino) fluoran, 3-di-n-butylamino-7- (2′-chlorophenylamino ) Fluoran, 3-N-isopentyl-N-ethylamino-7- (2′-chlorophenylamino) fluoran,

3-Nn-hexyl-N-ethylamino-7- (2'-chlorophenylamino) fluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-di-n-butylamino-6- Chloro-7-anilinofluoran, 3-diethylamino-6-methoxy-7-anilinofluoran, 3-di-n-butylamino-6-ethoxy-7-anilinofluoran, 3-pyrrolidino-6- Methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-morpholino-6-methyl-7-anilinofluoran, 3-dimethylamino-6-methyl-7- Anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3-di- -Pentylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-methylamino-6-methyl-7-anilinofluoran, 3-Nn-propyl-N-methylamino- 6-methyl-7-anilinofluoran, 3-NN-propyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-NN-butyl-N-methylamino-6- Methyl-7-anilinofluoran, 3-Nn-butyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isobutyl-N-methylamino-6-methyl-7- Anilinofluoran, 3-N-isobutyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran, 3 -Nn-hex 3-N-methylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-N-ethylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-Nn- Propylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-NNn-butylamino-6-methyl-7-anilinofluoran, 3-N-cyclohexyl-Nn-hexylamino -6-methyl-7-anilinofluoran, 3-N-cyclohexyl-NNn-octylamino-6-methyl-7-anilinofluoran,

3-N- (2'-methoxyethyl) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (2'-methoxyethyl) -N-ethylamino-6-methyl-7 -Anilinofluoran, 3-N- (2'-methoxyethyl) -N-isobutylamino-6-methyl-7-anilinofluoran, 3-N- (2'-ethoxyethyl) -N-methylamino -6-methyl-7-anilinofluoran, 3-N- (2'-ethoxyethyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (3'-methoxypropyl ) -N-methylamino-6-methyl-7-anilinofluoran, 3-N- (3'-methoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (3'-ethoxypropyl) -N- Tylamino-6-methyl-7-anilinofluoran, 3-N- (3'-ethoxypropyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (2'-tetrahydro Furfuryl) -N-ethylamino-6-methyl-7-anilinofluoran, 3-N- (4'-methylphenyl) -N-ethylamino-6-methyl-7-anilinofluoran, 3- Diethylamino-6-ethyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (3'-methylphenylamino) fluoran, 3-diethylamino-6-methyl-7- (2 ', 6'- Dimethylphenylamino) fluoran, 3-di-n-butylamino-6-methyl-7- (2 ', 6'-dimethylphenylamino) fluoran, 3-di-n-butylamino-7- 2 ', 6'-dimethylphenylamino) fluoran, 2,2-bis [4'-(3-N-cyclohexyl-N-methylamino-6-methylfluoran) -7-ylaminophenyl] propane, 3- Fluoranes such as [4 '-(4-phenylaminophenyl) aminophenyl] amino-6-methyl-7-chlorofluorane and 3- [4'-(dimethylaminophenyl)] amino-5,7-dimethylfluorane Kind,

3- (2-methyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-n-propoxycarbonylamino-4-di-n -Propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-methylamino-4-di-n-propylaminophenyl) -3- (1 -Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-methyl-4-di-n-hexylaminophenyl) -3- (1-n-octyl-2-methylindole-3- Yl) -4,7-diazaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (1-n-octyl-2-methylindole 3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy- 4-diethylaminophenyl) -3- (1-octyl-2-methylindol-3-yl) -4 or 7-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2 -Methylindol-3-yl) -4 or 7-azaphthalide, 3- (2-hexyloxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4- or 7- Azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide, -(2-butoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalide 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methylnaphtho (3-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran-3,6-bis (dimethylamino) fluorene-9-spiro Phthalides such as -3 ′-(6′-dimethylamino) phthalide, 3,6-bis (diethylamino) fluorene-9-spiro-3 ′-(6′-dimethylamino) phthalide,

In addition, 2'-anilino-6 '-(N-ethyl-N-isopentyl) amino-3'-methylspiro [isobenzofuran-1 (3H), 9'-(9H) xanthen-3-one, 2'-anilino -6 '-(N-ethyl-N- (4-methylphenyl)) amino-3'-methylspiro [isobenzofuran-1 (3H), 9'-(9H) xanthen] -3-one, 3'-N , N-Dibenzylamino-6'-N, N-diethylaminospiro [isobenzofuran-1 (3H), 9 '-(9H) xanthen] -3-one, 2'-(N-methyl-N-phenyl) Amino-6 '-(N-ethyl-N- (4-methylphenyl)) aminospiro [isobenzofuran-1 (3H), 9'-(9H) xanthen] -3-one.

Above all, the acid color former used in the present disclosure may be at least one compound selected from the group consisting of a spiropyran compound, a spirooxazine compound, a spirolactone compound, and a spirolactam compound from the viewpoint of coloration. preferable.
The hue of the dye after coloring is preferably green, blue or black from the viewpoint of visibility.

Commercially available products can also be used as the acid colorant. ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H -3035, BLUE203, ATP, H-1046, H-2114 (all manufactured by Fukui Yamada Chemical Industry Co., Ltd.), ORANGE-DCF, Vermilion-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF , TH-107 (both manufactured by Hodogaya Chemical Co., Ltd.), ODB, ODB-2, ODB-4, ODB-250, ODB-BlackXV, Blue-63, Blue-502, GN-169, GN-2, Gre n-118, Red-40, Red-8 (manufactured by Yamamoto Chemicals Co., Ltd.), crystal violet lactone (manufactured by Tokyo Kasei Kogyo Co., Ltd.), and the like. Among these commercial products, ETAC, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, Blue-63 , GN-169, and crystal violet lactone are preferable because the visible light absorption of the formed film is good.

These acid colorants may be used alone or in combination of two or more.
The content of the acid colorant is preferably from 0.5% by mass to 10% by mass, more preferably from 1% by mass to 5% by mass, based on the total mass of the image recording layer, from the viewpoint of color developability. preferable.

<< other binder polymer >>
The image recording layer may contain a binder polymer (other binder polymer) having neither a radical polymerizable group nor a cationic polymerizable group from the viewpoints of UV ink printing durability and on-press developability.
As the other binder polymer, a (meth) acrylic resin, a polyvinyl acetal resin, or a polyurethane resin is preferable.

The other binder polymer may contain one kind alone or two or more kinds.
The content of the other binder polymer is preferably smaller than the content of the binder polymer having a radical polymerizable group, and is preferably smaller than the content of the binder polymer having a cationic polymerizable group.

<< Chain transfer agent >>
The image recording layer may contain a chain transfer agent. The chain transfer agent contributes to improving the strength of the image recording layer and the printing durability of the resulting lithographic printing plate.
As the chain transfer agent, a thiol compound is preferable, a thiol having 7 or more carbon atoms is more preferable from the viewpoint of a boiling point (difficulty of volatilization), and a compound having a mercapto group on an aromatic ring (aromatic thiol compound) is further preferable. The thiol compound is preferably a monofunctional thiol compound.

Specific examples of the chain transfer agent include the following compounds.

Only one type of chain transfer agent may be added, or two or more types may be used in combination.
The content of the chain transfer agent is preferably 0.01% by mass to 50% by mass, more preferably 0.05% by mass to 40% by mass, and more preferably 0.1% by mass to 30% by mass based on the total mass of the image recording layer. % Is more preferred.

<< Low molecular weight hydrophilic compound >>
The image recording layer may contain a low molecular weight hydrophilic compound (also simply referred to as “hydrophilic compound”) from the viewpoints of UV ink printing durability and on-press developability. The low molecular weight hydrophilic compound is preferably a compound having a molecular weight of less than 1,000, more preferably a compound having a molecular weight of less than 800, and further preferably a compound having a molecular weight of less than 500.
Examples of the low-molecular hydrophilic compound include, for example, water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, glycols such as tripropylene glycol and ether or ester derivatives thereof, glycerin, Polyols such as pentaerythritol and tris (2-hydroxyethyl) isocyanurate, organic amines such as triethanolamine, diethanolamine and monoethanolamine and salts thereof, and organic sulfones such as alkylsulfonic acid, toluenesulfonic acid and benzenesulfonic acid. Acids and salts thereof, organic sulfamic acids and salts thereof such as alkylsulfamic acid, organic sulfuric acids and salts thereof such as alkyl sulfate and alkyl ether sulfate, and phenylphosphonic acid Organic phosphonic acids and salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, organic carboxylic acids and salts thereof such as amino acids, betaines, and the like.

It is preferable that the low molecular weight hydrophilic compound contains at least one selected from polyols, organic sulfates, organic sulfonates, and betaines.

Specific examples of the organic sulfonates include alkyl sulfonates such as sodium n-butylsulfonate, sodium n-hexylsulfonate, sodium 2-ethylhexylsulfonate, sodium cyclohexylsulfonate and sodium n-octylsulfonate; Sodium 8,8,11-trioxapentadecane-1-sulfonate, sodium 5,8,11-trioxaheptadecane-1-sulfonate, 13-ethyl-5,8,11-trioxaheptadecane-1-sulfonate Alkyl sulfonates containing an ethylene oxide chain such as sodium silicate, sodium 5,8,11,14-tetraoxatetracosane-1-sulfonate; sodium benzenesulfonate, sodium p-toluenesulfonate, p-hydroxybenzenesulfonic acid Na Sodium, sodium p-styrenesulfonate, sodium dimethyl-5-sulfonate isophthalate, sodium 1-naphthylsulfonate, sodium 4-hydroxynaphthylsulfonate, disodium 1,5-naphthalenedisulfonic acid, 1,3,6- Aryl sulfonates such as trisodium naphthalene trisulfonate, and compounds described in paragraphs 0026 to 0031 of JP-A-2007-276454 and paragraphs 0020 to 0047 of JP-A-2009-154525 are exemplified. The salt may be a potassium salt or a lithium salt.

(4) Examples of the organic sulfates include alkyl, alkenyl, alkynyl, aryl and heterocyclic monoether sulfates of polyethylene oxide. The number of ethylene oxide units is preferably from 1 to 4, and the salt is preferably a sodium salt, a potassium salt or a lithium salt. Specific examples include the compounds described in paragraphs 0034 to 0038 of JP-A-2007-276454.

As the betaines, compounds in which the number of carbon atoms in the hydrocarbon substituent on the nitrogen atom is 1-5 are preferable. Specific examples include trimethylammonium acetate, dimethylpropylammonium acetate, and 3-hydroxy-4-trimethylammonium. Obutyrate, 4- (1-pyridinio) butyrate, 1-hydroxyethyl-1-imidazolioacetate, trimethylammonium methanesulfonate, dimethylpropylammonium methanesulfonate, 3-trimethylammonio-1-propanesulfonate, 3 -(1-pyridinio) -1-propanesulfonate and the like.

Since the low molecular weight hydrophilic compound has a small structure of the hydrophobic portion and little surface activity, the fountain solution penetrates into the exposed portion (image portion) of the image recording layer and lowers the hydrophobicity and film strength of the image portion. Therefore, it is possible to maintain good ink receptivity and printing durability of the image recording layer.

The content of the low-molecular hydrophilic compound is preferably 0.5% by mass to 20% by mass with respect to the total mass of the image recording layer, from the viewpoints of developability and printing durability of the resulting lithographic printing plate. 1 mass% to 15 mass% is more preferable, and 2 mass% to 10 mass% is further preferable. Within this range, good on-press developability and printing durability can be obtained.
The low molecular weight hydrophilic compound may be used alone or in combination of two or more.

<<<< sensitizer >>
The image recording layer may contain a sensitizing agent such as a phosphonium compound, a nitrogen-containing low molecular weight compound, or an ammonium group-containing polymer in order to improve the inking property of the resulting lithographic printing plate. In particular, when an inorganic layered compound is contained in the protective layer, these compounds function as a surface coating agent for the inorganic layered compound and can suppress a decrease in the inking property of the inorganic layered compound during printing.
As the sensitizer, it is preferable to use a phosphonium compound, a nitrogen-containing low-molecular compound, and an ammonium group-containing polymer in combination, and it is preferable to use a phosphonium compound, a quaternary ammonium salt, and an ammonium group-containing polymer in combination. Is more preferred.

Examples of the phosphonium compound include the phosphonium compounds described in JP-A-2006-297907 and JP-A-2007-50660. Specific examples include tetrabutylphosphonium iodide, butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 1,4-bis (triphenylphosphonio) butane = di (hexafluorophosphate), 1,7-bis (tri Phenylphosphonio) heptane sulfate, 1,9-bis (triphenylphosphonio) nonane = naphthalene-2,7-disulfonate and the like.

窒素 Examples of the nitrogen-containing low molecular weight compound include amine salts and quaternary ammonium salts. Further, imidazolinium salts, benzimidazolinium salts, pyridinium salts, and quinolinium salts are also included. Among them, quaternary ammonium salts and pyridinium salts are preferred. Specific examples include tetramethylammonium = hexafluorophosphate, tetrabutylammonium = hexafluorophosphate, dodecyltrimethylammonium = p-toluenesulfonate, benzyltriethylammonium = hexafluorophosphate, benzyldimethyloctylammonium = hexafluorophosphate Phthalate, benzyldimethyldodecylammonium = hexafluorophosphate, and the compounds described in paragraphs 0021 to 0037 of JP-A-2008-284858 and paragraphs 0030 to 0057 of JP-A-2009-90645 are exemplified.

The ammonium group-containing polymer only needs to have an ammonium group in its structure, and is preferably a polymer containing (meth) acrylate having an ammonium group in a side chain as a copolymer component in an amount of 5 mol% to 80 mol%. Specific examples include the polymers described in paragraphs 0089 to 0105 of JP-A-2009-208458.

The ammonium salt-containing polymer preferably has a reduced specific viscosity (unit: ml / g) in the range of 5 to 120, preferably 10 to 110, determined according to the measuring method described in JP-A-2009-208458. Are more preferable, and those in the range of 15 to 100 are particularly preferable. When the reduced specific viscosity is converted to a weight average molecular weight (Mw), it is preferably 10,000 to 150,0000, more preferably 17,000 to 140,000, and particularly preferably 20,000 to 130,000.

Hereinafter, specific examples of the ammonium group-containing polymer will be described.
(1) 2- (trimethylammonio) ethyl methacrylate = p-toluenesulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 10/90, Mw 45,000)
(2) 2- (trimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, Mw 60,000)
(3) 2- (ethyldimethylammonio) ethyl methacrylate = p-toluenesulfonate / hexyl methacrylate copolymer (molar ratio 30/70, Mw 45,000)
(4) 2- (trimethylammonio) ethyl methacrylate = hexafluorophosphate / 2-ethylhexyl methacrylate copolymer (molar ratio 20/80, Mw 60,000)
(5) 2- (trimethylammonio) ethyl methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40/60, Mw 70,000)
(6) 2- (butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 25/75, Mw 65,000)
(7) 2- (butyldimethylammonio) ethyl acrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, Mw 65,000)
(8) 2- (butyldimethylammonio) ethyl methacrylate = 13-ethyl-5,8,11-trioxa-1-heptadecane sulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80) , Mw 75,000)
(9) 2- (butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate / 2-hydroxy-3-methacryloyloxypropyl methacrylate copolymer (molar ratio 15/80/5) , Mw 65,000)

The content of the sensitizer is preferably 0.01% by mass to 30.0% by mass, more preferably 0.1% by mass to 15.0% by mass, and more preferably 1% by mass, based on the total mass of the image recording layer. % To 10% by mass is more preferred.

<< Solvent >>
When the image recording layer is formed, the image recording layer may be formed by using a solvent and dissolving or dispersing each component of the image recording layer as a composition and drying the composition.
As the solvent, a known solvent can be used. Specifically, for example, water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene Glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy -1-propanol, methoxymethoxy Knol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone , Methyl lactate, ethyl lactate and the like. The solvents can be used alone or in combination of two or more.
The solid content concentration in the composition is preferably 1% by mass to 50% by mass. The solid content concentration is the concentration of all components excluding the solvent.

<Other ingredients>
Known additives can be added to the image recording layer as other components. Examples of the additive include a surfactant, a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic particles, and an inorganic layered compound. Specifically, the description in paragraphs 0114 to 0159 of JP-A-2008-284817 can be referred to.

-Formation of image recording layer-
The image recording layer in the lithographic printing plate precursor according to the present disclosure is coated, for example, by dispersing or dissolving the necessary components described above in a known solvent, as described in paragraphs 0142 to 0143 of JP-A-2008-195018. A liquid can be formed by preparing a liquid, applying a coating liquid on a support by a known method such as coating with a bar coater, and drying.
The coating amount (solid content) of the image recording layer after coating and drying varies depending on the application, but from the viewpoint of obtaining good sensitivity and good film characteristics of the image recording layer, from 0.3 g / m ² to 3.0 g / m. m ² is preferred.

<Undercoat layer>
The lithographic printing plate precursor according to the present disclosure preferably has an undercoat layer (sometimes called an intermediate layer) between the image recording layer and the support. The undercoat layer enhances the adhesion between the support and the image recording layer in the exposed area, and easily peels off the image recording layer from the support in the unexposed area. It contributes to improving. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, which also has the effect of preventing heat generated by exposure from diffusing to the support and lowering the sensitivity.

化合物 Examples of the compound used for the undercoat layer include a polymer having an adsorptive group and a hydrophilic group that can be adsorbed on the support surface. In order to improve the adhesion to the image recording layer, a polymer having an adsorptive group and a hydrophilic group and further having a crosslinkable group is preferable. The compound used for the undercoat layer may be a low molecular compound or a polymer. The compounds used in the undercoat layer may be used as a mixture of two or more as necessary.

When the compound used in the undercoat layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group is preferable.
Examples of the adsorptive group that can be adsorbed on the surface of the support include a phenolic hydroxy group, a carboxy group, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ —, and —COCH ₂ COCH _3. Is preferred. As the hydrophilic group, a sulfo group or a salt thereof, and a salt of a carboxy group are preferable. As the crosslinkable group, an acryl group, a methacryl group, an acrylamide group, a methacrylamide group, an allyl group, and the like are preferable.
The polymer may have a polar substituent of the polymer, a substituent having a counter charge with the polar substituent and a crosslinkable group introduced by salt formation with a compound having an ethylenically unsaturated bond, Other monomers, preferably hydrophilic monomers, may be further copolymerized.

Specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679 and an ethylenic double bond described in JP-A-2-304441 are disclosed. A preferred example is a phosphorus compound having a heavy bond reactive group. JP-A-2005-238816, JP-A-2005-125749, JP-A-2006-239867, JP-A-2006-215263, crosslinkable groups (preferably ethylenically unsaturated bonding groups), and a support Low-molecular or high-molecular compounds having a functional group and a hydrophilic group that interact with the surface are also preferably used.
More preferred are high-molecular polymers having an adsorptive group, a hydrophilic group, and a crosslinkable group that can be adsorbed on the support surface described in JP-A-2005-125749 and JP-A-2006-188038.

The content of the ethylenically unsaturated bonding group in the polymer used for the undercoat layer is preferably 0.1 mmol to 10.0 mmol, more preferably 0.2 mmol to 5.5 mmol, per 1 g of the polymer.
The weight average molecular weight (Mw) of the polymer used for the undercoat layer is preferably 5,000 or more, more preferably 10,000 to 300,000.

The undercoat layer is, in addition to the undercoat layer compound described above, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, an amino group or a functional group having a polymerization inhibiting ability, and a support surface in order to prevent contamination with time. Such as 1,4-diazabicyclo [2.2.2] octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid, Ethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, etc.).

The undercoat layer is applied by a known method. The coating amount (solid content) of the undercoat layer is preferably from 0.1 mg / m ² to 100 mg / m ^2, more preferably from 1 mg / m ² to 30 mg / m ² .

<Protective layer>
The lithographic printing plate precursor according to the present disclosure preferably has a protective layer (sometimes called an overcoat layer) on the image recording layer. The protective layer has a function of preventing damage to the image recording layer and a function of preventing ablation at the time of high-intensity laser exposure, in addition to a function of suppressing an image formation inhibition reaction by blocking oxygen.

The protective layer having such properties is described, for example, in US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729. As the polymer having low oxygen permeability used for the protective layer, any of a water-soluble polymer and a water-insoluble polymer can be appropriately selected and used, and if necessary, a mixture of two or more types may be used. it can. Specific examples include polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose derivatives, poly (meth) acrylonitrile, and the like.
As the modified polyvinyl alcohol, an acid-modified polyvinyl alcohol having a carboxy group or a sulfo group is preferably used. Specific examples include modified polyvinyl alcohols described in JP-A-2005-250216 and JP-A-2006-259137.

The protective layer preferably contains an inorganic layered compound in order to enhance oxygen barrier properties. The inorganic layered compound is a particle having a thin tabular shape, for example, a group of mica such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectotype represented by the formula: 3MgO.4SiO.H ₂ O Light, zirconium phosphate and the like.
The inorganic layer compound preferably used is a mica compound. Examples of the mica compound include a compound represented by the formula: A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂ [where A is any of K, Na, and Ca; One of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. ] Mica groups such as natural mica and synthetic mica.

In the mica group, natural mica includes muscovite, soda mica, phlogopite, biotite and scale mica. Examples of the synthetic mica include non-swelling mica such as fluorophlogopite KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ and potassium tetrasilicic mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilic mica NaMg _{2. 5} (Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite-based Na or Li hectorite (Na, Li) _８ Mg _{2 / 5} Li _1/8 (Si ₄ O ₁₀ ) F _{2 and} other swellable mica. Further, synthetic smectite is also useful.

Among the above mica compounds, fluorine-based swellable mica is particularly useful. That is, the swellable synthetic mica has a laminated structure composed of a unit crystal lattice layer having a thickness of about 10 ° to 15 ° (1 ° = 0.1 nm), and the substitution of metal atoms in the lattice is significantly larger than other clay minerals. As a result, the lattice layer has a shortage of positive charges, and cations such as Li ⁺ , Na ⁺ , Ca ²⁺ , and Mg ²⁺ are adsorbed between the layers to compensate for the shortage. The cations interposed between these layers are called exchangeable cations and can exchange with various cations. In particular, when the cations between the layers are Li ⁺ and Na ⁺ , the ionic radius is small, so that the bond between the layered crystal lattices is weak, and the swells greatly with water. When shear is applied in this state, it is easily cleaved and forms a stable sol in water. Swellable synthetic mica has a strong tendency, and is particularly preferably used.

形状 From the viewpoint of diffusion control, the shape of the mica compound is preferably as thin as possible, and the planar size is preferably as large as not to impair the smoothness of the coated surface and the transmittance of active light. Therefore, the aspect ratio is preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more. The aspect ratio is the ratio of the major axis to the thickness of the particle, and can be measured, for example, from a projection of a particle by a micrograph. The greater the aspect ratio, the greater the effect obtained.

粒子 The average particle diameter of the mica compound is preferably 0.3 μm to 20 μm, more preferably 0.5 μm to 10 μm, and particularly preferably 1 μm to 5 μm. The average thickness of the particles is preferably 0.1 μm or less, more preferably 0.05 μm or less, particularly preferably 0.01 μm or less. Specifically, for example, in the case of a swellable synthetic mica which is a typical compound, the preferred embodiment has a thickness of about 1 nm to 50 nm and a plane size (major axis) of about 1 μm to 20 μm.

The content of the inorganic layered compound is preferably from 1% by mass to 60% by mass, more preferably from 3% by mass to 50% by mass, based on the total mass of the protective layer. Even when a plurality of types of inorganic layered compounds are used in combination, the total amount of the inorganic layered compounds is preferably the above-mentioned content. Within the above range, oxygen barrier properties are improved, and good sensitivity is obtained. Further, it is possible to prevent a decrease in the inking property.

The protective layer may contain known additives such as a plasticizer for imparting flexibility, a surfactant for improving coating properties, and inorganic particles for controlling surface slipperiness. Further, the sensitizer described in the image recording layer may be contained in the protective layer.

The protective layer is applied by a known method. The coating amount of the protective layer (solid content) is preferably from ^{^{0.01g / m 2 ~ 10g / m}} 2, more preferably ^{^{0.02g / m 2 ~ 3g / m}} 2, 0.02g / m 2 ~ 1g / m ² is particularly preferred.

(How to make a lithographic printing plate)
The lithographic printing plate precursor according to the present disclosure is subjected to image exposure and development processing to produce a lithographic printing plate.
The method for producing a lithographic printing plate according to the present disclosure includes a step of imagewise exposing the lithographic printing plate precursor according to the present disclosure to form an exposed part and an unexposed part (hereinafter, also referred to as an “exposure step”). Preferably, the method further includes a step of supplying at least one of a printing ink and a dampening solution to remove the unexposed portion (hereinafter, also referred to as an “on-press development step”).
Further, the method of preparing a lithographic printing plate according to the present disclosure includes a step of exposing the lithographic printing plate precursor according to the present invention to an image, and a step of exposing the unexposed portion of the image recording layer with a one-bath developer having a pH of 2 to 11. It is preferable to include a step of removing.
Hereinafter, a preferred embodiment of each step of the method for preparing a lithographic printing plate according to the present disclosure and the lithographic printing method according to the present disclosure will be described in order. The lithographic printing plate precursor according to the present disclosure can also be developed with a developer.

<Exposure process>
The method for preparing a lithographic printing plate according to the present disclosure preferably includes an exposure step of exposing the lithographic printing plate precursor according to the present disclosure imagewise to form an exposed portion and an unexposed portion. The lithographic printing plate precursor according to the present disclosure is preferably exposed imagewise through a transparent original having a line image, a halftone dot image, or the like, or is imagewise exposed by laser light scanning using digital data.
The wavelength of the light source is preferably from 750 nm to 1,400 nm. As a light source having a wavelength of 750 nm to 1,400 nm, a solid-state laser and a semiconductor laser that emit infrared rays are suitable. As for the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is 10 mJ / cm ² to 300 mJ / cm ^2. preferable. Further, it is preferable to use a multi-beam laser device in order to shorten the exposure time. The exposure mechanism may be any of an internal drum system, an external drum system, a flatbed system, and the like.
Image exposure can be performed by a conventional method using a plate setter or the like. In the case of on-press development, after the lithographic printing plate precursor is mounted on the printing press, image exposure may be performed on the printing press.

<On-press development process>
The method for producing a lithographic printing plate according to the present disclosure preferably includes an on-press development step of supplying at least one of a printing ink and a fountain solution to remove the unexposed portion.
Further, the method of preparing a lithographic printing plate according to the present disclosure may be performed by a method of developing with a developer (developer processing method).
The on-press development method will be described below.

-On-press development method-
In the on-press development system, an imagewise exposed lithographic printing plate precursor is prepared by supplying an oil-based ink and an aqueous component on a printing press, and removing the image-forming layer in the non-image area to produce a lithographic printing plate. Is preferred.
That is, after imagewise exposing the lithographic printing plate precursor, the lithographic printing plate precursor is directly mounted on a printing press without any development processing, or the lithographic printing plate precursor is mounted on a printing press, and then image-exposed on the printing press. When an oil-based ink and an aqueous component are supplied and printing is performed, an uncured image forming layer is formed in a non-image portion at an early stage during printing by one or both of the supplied oil-based ink and the aqueous component. It is removed by dissolution or dispersion, and a hydrophilic surface is exposed at that portion. On the other hand, in the exposed portion, the image forming layer cured by exposure forms an oil-based ink receiving portion having a lipophilic surface. An oil-based ink or an aqueous component may be supplied to the plate first, but the oil-based ink is supplied first in order to prevent the aqueous component from being contaminated by the components of the image forming layer from which the aqueous component has been removed. Is preferred. In this way, the lithographic printing plate precursor is developed on-press on a printing press and used as is for printing a large number of sheets. As the oil-based ink and the aqueous component, a normal printing ink for lithographic printing and a fountain solution are suitably used.

レーザー As a laser for imagewise exposing the lithographic printing plate precursor according to the present disclosure containing the polymerization initiator and the polymerizable compound, the wavelength of the light source is preferably from 300 nm to 450 nm or from 750 nm to 1,400 nm. In the case of a light source of 300 nm to 450 nm, a lithographic printing plate precursor containing a sensitizing dye having an absorption maximum in this wavelength region in an image recording layer is preferably used, and the light source of 750 to 1,400 nm described above is preferably used. Can be As a light source of 300 nm to 450 nm, a semiconductor laser is preferable.

As the one-bath developer having a pH of 2 to 11, a known developer can be used, and examples thereof include a developer having a pH of 2 to 11 containing at least one of a surfactant and a water-soluble polymer compound. In the conventional developing process using a strong alkali developing solution, the protective layer is removed by a pre-washing step, then alkali developing is performed, alkalis are removed by washing in a post-washing step, gum solution processing is performed, and drying is performed in a drying step. It was necessary to do. By using the above-mentioned developer containing a surfactant or a water-soluble polymer compound, development-gum solution treatment can be performed simultaneously. Therefore, the post-water washing step is not particularly required, and after performing the development and the gum solution treatment with one liquid, the drying step can be performed. Further, since the removal of the protective layer can be performed simultaneously with the development and the gum solution treatment, a pre-washing step is not particularly required. After the development, it is preferable to remove excess developer using a squeeze roller or the like, and then perform drying.

<Printing process>
The lithographic printing method according to the present disclosure includes a printing step of supplying a printing ink to the lithographic printing plate developed on-press in the on-press development step to print a recording medium.
The printing ink is not particularly limited, and various known inks can be used as desired. Further, as the printing ink, oil-based ink or ultraviolet-curable ink (UV ink) is preferable, and UV ink is more preferable.
In the printing step, a dampening solution may be supplied as needed.
Further, the printing step may be performed continuously to the on-press development step without stopping the printing press.
The recording medium is not particularly limited, and a known recording medium can be used as desired.

In the method of preparing a lithographic printing plate from the lithographic printing plate precursor according to the present disclosure, and the lithographic printing method according to the present disclosure, if necessary, before the exposure, during the exposure, between the exposure and the development, the lithographic printing The entire surface of the plate master may be heated. By such heating, the image forming reaction in the image forming layer is promoted, and advantages such as improvement in sensitivity and printing durability, stabilization of sensitivity, and the like may be generated. Heating before development is preferably performed under mild conditions of 150 ° C. or less. According to the above aspect, problems such as hardening of the non-image portion can be prevented. It is preferable to use very strong conditions for heating after development, and it is preferable that the temperature be in the range of 100 ° C. to 500 ° C. When the content is in the above range, a sufficient image strengthening effect can be obtained, and problems such as deterioration of the support and thermal decomposition of the image portion can be suppressed.

Hereinafter, the present embodiment will be described in detail with reference to examples, but the present embodiment is not limited thereto. In the polymer compounds, unless otherwise specified, the molecular weight is a weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC), and the ratio of the constituent units is a mole percentage. Further, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

・ Synthesis of polymer having cationically polymerizable group <Synthesis of binder polymer KB-1>

In a three-necked flask equipped with a condenser and a stirrer, 23.1 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was weighed and stirred at 70 ° C. while flowing nitrogen. Next, 9.01 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 25.4 g of 2- (2-methoxyethoxy) ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and VEEM (2- (methacrylic acid 2- ( 15.02 g of 2-vinyloxyethoxy) ethyl (manufactured by Nippon Shokubai Co., Ltd.), 0.87 g of dipentaerythritol hexakis (3-mercaptopropionate) manufactured by Wako Pure Chemical Industries, Ltd., V-601 (dimethyl) 0.15 g of 2,2'-azobis (2-methylpropionate), manufactured by Wako Pure Chemical Industries, Ltd., and 92.3 g of propylene glycol-1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) are weighed. Stir and dissolve. This solution was added dropwise to the three-necked flask over 2 hours, followed by stirring at 70 ° C. for 2 hours. Thereafter, the internal temperature was raised to 90 ° C., the mixture was stirred for 2 hours, cooled to room temperature (25 ° C., the same applies hereinafter), and 35.2 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added. 200 g of the desired binder polymer KB-1 was obtained.
The weight average molecular weight (Mw) of KB-1 in terms of polyethylene glycol determined by gel permeation chromatography (GPC) was 41,500.

In a three-necked flask equipped with a condenser and a stirrer, 23.1 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was weighed and stirred at 70 ° C. while flowing nitrogen. Next, 9.01 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 25.4 g of 2- (2-methoxyethoxy) ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and VEEM (2- (methacrylic acid 2- ( 15.02 g of 2-vinyloxyethoxy) ethyl (manufactured by Nippon Shokubai Co., Ltd.), 0.65 g of dipentaerythritol hexakis (3-mercaptopropionate) manufactured by Wako Pure Chemical Industries, Ltd., V-601 (dimethyl) 0.11 g of 2,2′-azobis (2-methylpropionate), manufactured by Wako Pure Chemical Industries, Ltd., and 92.3 g of propylene glycol-1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) are weighed. Stir and dissolve. This solution was added dropwise to the three-necked flask over 2 hours, followed by stirring at 70 ° C. for 2 hours. Thereafter, the internal temperature was raised to 90 ° C., the mixture was stirred for 2 hours, cooled to room temperature (25 ° C., the same applies hereinafter), and 35.2 g of propylene glycol-1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added. Thus, 200 g of the intended binder polymer KB-2 was obtained.
The weight average molecular weight (Mw) of KB-2 in terms of polyethylene glycol determined by gel permeation chromatography (GPC) was 62,100.

In a three-necked flask equipped with a condenser and a stirrer, 12.26 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was weighed, and stirred at 70 ° C. while flowing nitrogen. Next, 9.01 g of methyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.46 g of methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2- (2-methoxyethoxy) ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) 25.4 g), 0.87 g of dipentaerythritol hexakis (3-mercaptopropionate) (manufactured by Wako Pure Chemical Industries, Ltd.), V-601 (dimethyl 2,2'-azobis (2-methylpro 0.15 g of Pionate (manufactured by Wako Pure Chemical Industries, Ltd.) and 49.1 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) were weighed, stirred, and dissolved. The mixture was added dropwise to the flask over 2 hours, and stirred for 2 hours at 70 ° C. Thereafter, the internal temperature was raised to 90 ° C., and the mixture was stirred for 3 hours. (Manufactured by Tokyo Chemical Industry Co., Ltd.), 43.7 g, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical (manufactured by Tokyo Chemical Industry Co., Ltd.) 1.01 g, allyl glycidyl ether 9.49 g (manufactured by Wako Pure Chemical Industries, Ltd.) and 1.35 g of tetraethylammonium bromide were added, and the mixture was stirred at 90 ° C. for 15 hours and cooled to room temperature (25 ° C., the same applies hereinafter). 67.9 g of ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to obtain 225 g of the intended binder KB-3.
The weight average molecular weight (Mw) of KB-3 in terms of polyethylene glycol determined by gel permeation chromatography (GPC) was 40,400.

・ Synthesis of polymer having radical polymerizable group <Synthesis of binder polymer RB-1>

In a three-necked flask equipped with a condenser and a stirrer, 12.6 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was weighed and stirred at 70 ° C. while flowing nitrogen. Then, 9.01 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 25.4 g of 2- (2-methoxyethoxy) ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 6.46 g), 0.87 g of dipentaerythritol hexakis (3-mercaptopropionate) manufactured by Wako Pure Chemical Industries, Ltd., and V-601 (dimethyl 2,2'-azobis (2-methylpro Pionate), 0.15 g of Wako Pure Chemical Industries, Ltd.) and 49.1 g of propylene glycol-1-monomethyl ether (Tokyo Kasei Kogyo) were weighed, stirred and dissolved. This solution was added dropwise to the three-necked flask over 2 hours, followed by stirring at 70 ° C. for 2 hours. Thereafter, the internal temperature was raised to 90 ° C., the mixture was stirred for 2 hours, and cooled to room temperature (25 ° C., the same applies hereinafter). Then, 43.6 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical (manufactured by Tokyo Chemical Industry Co., Ltd.) 1.01 g, glycidyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 11.8 g, and tetraethylammonium bromide 1.35 g were added, and the mixture was stirred at 90 ° C. for 18 hours, and cooled to room temperature (25 ° C., the same applies hereinafter). did. 67.9 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to obtain 225 g of the target binder polymer RB-1.
The weight average molecular weight (Mw) of RB-1 in terms of polyethylene glycol by gel permeation chromatography (GPC) was 41,500.

In a three-necked flask equipped with a condenser and a stirrer, 11.6 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was weighed and stirred at 70 ° C. while flowing nitrogen. Subsequently, 3.00 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 22.6 g of 2- (2-methoxyethoxy) ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and methacrylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 12.91 g, dipentaerythritol hexakis (3-mercaptopropionate), 1.74 g, manufactured by Wako Pure Chemical Industries, Ltd., V-601 (dimethyl 2,2'-azobis (2-methylpro Pionate), 0.31 g of Wako Pure Chemical Industries, Ltd.) and 46.2 g of propylene glycol-1-monomethyl ether (Tokyo Kasei Kogyo Co., Ltd.) were weighed, stirred and dissolved. This solution was added dropwise to the three-necked flask over 2 hours, followed by stirring at 70 ° C. for 2 hours. Thereafter, the internal temperature was raised to 90 ° C., the mixture was stirred for 2 hours, and cooled to room temperature (25 ° C., the same applies hereinafter). Then, 51.3 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical (manufactured by Tokyo Chemical Industry Co., Ltd.) 1.01 g, 23.7 g of glycidyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) and 2.70 g of tetraethylammonium bromide are added, and the mixture is stirred at 90 ° C. for 18 hours and cooled to room temperature (25 ° C., the same applies hereinafter). did. 100.2 g of propylene glycol 1-monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to obtain 277 g of the intended binder polymer RB-2.
The weight average molecular weight (Mw) of RB-2 as converted to polyethylene glycol by gel permeation chromatography (GPC) was 20,800.

・ Synthesis of monomer having cationic polymerizable group <Synthesis of monomer KM-1>

In a three-necked flask equipped with a condenser and a stirrer, 21.8 g of pyromellitic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.), 27.8 g of diethylene glycol monovinyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), and dehydrated pyridine ( 17.4 g of Tokyo Chemical Industry Co., Ltd., 115.7 g of dehydrated tetrahydrofuran (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.05 g of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.) are weighed and measured at 60 ° C. for 5 hours. Stirred. This was cooled to −5 ° C., and 24.62 g of thionyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 50.0 g of tetrahydrofuran and added dropwise over 2 hours. After the dropwise addition, the mixture was stirred at 0 ° C. for 2 hours, and 26.7 g of diethylene glycol monovinyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 2 hours. After the dropwise addition, the mixture was stirred for 2 hours and poured into 500 mL of ice water. This was extracted twice with 500 mL of ethyl acetate, washed twice with 500 mL of water, twice with 500 mL of a saturated aqueous solution of sodium hydrogen carbonate, washed with 500 mL of a saturated aqueous solution of sodium chloride, and then the solvent was removed with an evaporator. As a result, 48.8 g of the objective monomer KM-1 was obtained.
It was confirmed from the ¹ H-NMR spectrum (nuclear magnetic resonance spectrum) that it was the target substance.

17.26 g of tris (2-carboxyethyl) isocyanurate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 40.3 g of dehydrated tetrahydrofuran (manufactured by Tokyo Chemical Industry Co., Ltd.) were placed in a three-necked flask equipped with a condenser and a stirrer. Was cooled to −5 ° C. while stirring, and 18.7 g of thionyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 40.0 g of tetrahydrofuran and added dropwise over 2 hours. After the dropwise addition, the mixture was stirred at 0 ° C. for 2 hours, and 20.8 g of diethylene glycol monovinyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 2 hours. After the dropwise addition, the mixture was stirred for 2 hours and poured into 500 mL of ice water. This was extracted twice with 500 mL of ethyl acetate, washed twice with 500 mL of water, twice with 500 mL of a saturated aqueous solution of sodium hydrogen carbonate, washed with 500 mL of a saturated aqueous solution of sodium chloride, and then the solvent was removed with an evaporator. As a result, 28.8 g of the objective monomer KM-2 was obtained.
It was confirmed from the ¹ H-NMR spectrum (nuclear magnetic resonance spectrum) that it was the target substance.

・ Synthesis of particle material <Synthesis of isocyanate compound PA-1>
In a three-necked flask equipped with a condenser and a stirrer, 37.65 g of 4,4 ′-(2-hydroxybenzylidene) bis (2,3,6-trimethylphenol) (manufactured by Tokyo Chemical Industry Co., Ltd.), isophorone diisocyanate 89.66 g (manufactured by Tokyo Chemical Industry Co., Ltd.) and 127.31 g of ethyl acetate were weighed and stirred at 50 ° C. Next, 0.25 g of Neostan U-600 (manufactured by Nitto Kasei Co., Ltd .: bismuth catalyst) was added, and the mixture was reacted at 50 ° C. for 3 hours with stirring. A 35% by weight solution was obtained.

<Synthesis of Isocyanate Compound PA-2>
In a three-necked flask equipped with a condenser and a stirrer, 51.25 g of millionate MR-200 (polymethylene polyphenyl polyisocyanate, manufactured by Tosoh Corporation) and Blemmer AE-200 (polyethylene glycol monoacrylate, NOF CORPORATION) 27.03 g) and 145.38 g of methyl ethyl ketone (manufactured by Wako Pure Chemical Industries, Ltd.) were weighed and stirred at room temperature to obtain a homogeneous solution. Next, 0.08 g of 2,2,6,6-tetramethylpiperidine 1-oxyl free radical (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.16 g of Neostan U-600 (manufactured by Nitto Kasei Co., Ltd .: bismuth catalyst) were added. The mixture was added and reacted at 50 ° C. for 3 hours with stirring. A 35% by mass solution of the isocyanate compound PA-2 was obtained.

<Synthesis of Isocyanate Compound PB-1 Having Polyoxyalkylene Chain>
In a three-necked flask equipped with a condenser and a stirrer, 30.28 g of Takenate D-110N (trimethylolpropane-modified m-xylylenediisocyanate, manufactured by Mitsui Chemicals, Inc.) and polyethylene glycol monomethyl ether (Uniox M- 4000: 30.32 g of NOF Corporation and 60.56 g of methyl ethyl ketone (manufactured by Wako Pure Chemical Industries, Ltd.) were weighed and stirred while heating at 50 ° C. to form a uniform solution. Next, 0.13 g of Neostan U-600 (manufactured by Nitto Kasei Corporation: bismuth catalyst) was added, and the mixture was reacted at 50 ° C. for 5 hours with stirring. A 50% by mass solution of the isocyanate compound PB-1 having a polyoxyalkylene chain was obtained.

・ Synthesis of radical polymerizable and cationic polymerizable particles <Preparation of particle PR-1>
13.53 g of isocyanate compound PA-2, 3.39 g of isocyanate compound PB-1 having a polyoxyalkylene chain, and SR-399 (dipentaerythritol pentaacrylate, manufactured by Sartomer) 50% by mass ethyl acetate solution as a radical polymerizable monomer 9.5 g, as a cationically polymerizable monomer, 4.0 g of monomer KM-1 (50% by mass in ethyl acetate solution), 6.00 g of ethyl acetate, 2.6 surfactant surfactant Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) 3.82 g of a mass% aqueous solution was weighed out and homogeneously dissolved. This was mixed with 40 g of water and emulsified for 12 minutes at 12,000 rpm (revolutions per minute) using a homogenizer. Then, after stirring at 45 ° C. for 4 hours, 40 g of water was added, and the mixture was filtered with a filter cloth. The mixture was further stirred at 45 ° C. for 40 hours to obtain polymer particles PR-1. The average particle size of the dispersion of the polymer particles PR-1 was 0.20 μm.

<Preparation of Particle PR-2>
13.53 g of an isocyanate compound PA-2, 3.39 g of an isocyanate compound PB-1 having a polyoxyalkylene chain, 9.5 g of a 50% by mass SR-399 (manufactured by Sartomer) ethyl acetate solution as a radical polymerizable monomer, and cationic polymerization As a hydrophilic monomer, 4.0 g of monomer KM-2 (50% by mass in ethyl acetate solution), 6.00 g of ethyl acetate, 3.82 g of 2.6% by mass aqueous solution of surfactant Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) Was weighed to obtain a uniform solution. This was mixed with 40 g of water and emulsified at 12,000 rpm for 12 minutes using a homogenizer. Then, after stirring at 45 ° C. for 4 hours, 40 g of water was added, and the mixture was filtered with a filter cloth. The mixture was further stirred at 45 ° C. for 40 hours to obtain polymer particles PR-2. The average particle size of the dispersion of the polymer particles PR-2 was 0.17 μm.

<Preparation of Particle PR-3>
13.53 g of isocyanate compound PA-1; 3.39 g of isocyanate compound PB-1 having a polyoxyalkylene chain; 9.5 g of a 50% by mass SR-399 (manufactured by Sartomer) ethyl acetate solution as a radical polymerizable monomer; cationic polymerization As the reactive monomer, monomer KM-1 (50% by mass in ethyl acetate solution), 6.00 g of ethyl acetate, and 3.82 g of 2.6% by mass aqueous solution of surfactant Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) were weighed. To obtain a homogeneous solution. This was mixed with 40 g of water and emulsified at 12,000 rpm for 12 minutes using a homogenizer. Then, after stirring at 45 ° C. for 4 hours, 40 g of water was added, and the mixture was filtered with a filter cloth. The mixture was further stirred at 45 ° C. for 40 hours to obtain polymer particles PR-3. The average particle size of the dispersion of the polymer particles PR-3 was 0.22 μm.

<Preparation of Particle PR-4>
13.53 g of isocyanate compound PA-1; 3.39 g of isocyanate compound PB-1 having a polyoxyalkylene chain; 9.5 g of a 50% by mass SR-399 (manufactured by Sartomer) ethyl acetate solution as a radical polymerizable monomer; cationic polymerization As a hydrophilic monomer, 4.0 g of KM-2 (50 mass% ethyl acetate solution), 6.00 g of ethyl acetate, 3.82 g of 2.6 mass% aqueous solution of surfactant Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) were used. It was weighed and homogeneously dissolved. This was mixed with 40 g of water and emulsified at 12,000 rpm for 12 minutes using a homogenizer. Then, after stirring at 45 ° C. for 4 hours, 40 g of water was added, and the mixture was filtered with a filter cloth. The mixture was further stirred at 45 ° C. for 40 hours to obtain polymer particles PR-4. The average particle size of the dispersion of the polymer particles PR-4 was 0.24 μm.

Preparation of Particles Used in Comparative Example <Preparation of Particle P-1>
13.53 g of isocyanate compound PA-3, 3.39 g of isocyanate compound PB-1 having a polyoxyalkylene chain, 13.53 g of a 50 wt% polycyclic monomer SR-399 (manufactured by Sartomer), 13.53 g of ethyl acetate solution, and 6.00 g of ethyl acetate 3.82 g of a 2.6% by mass aqueous solution of a surfactant, Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.), was weighed and uniformly dissolved. This was mixed with 40 g of water and emulsified at 12,000 rpm for 12 minutes using a homogenizer. Then, after stirring at 45 ° C. for 4 hours, 40 g of water was added, and the mixture was filtered with a filter cloth. The mixture was further stirred at 45 ° C. for 40 hours to obtain polymer particles P-1. The average particle size of the dispersion liquid of polymer particles P-1 was 0.18 μm.

<Preparation of Particle P-2>
13.53 g of isocyanate compound PA-1; 3.39 g of isocyanate compound PB-1 having a polyoxyalkylene chain; 50 wt% ethyl acetate solution 13 of tris (2.3-epoxypropyl) isocyanurate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.53 g, 6.00 g of ethyl acetate, and 3.82 g of a 2.6% by mass aqueous solution of surfactant Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) were weighed and uniformly dissolved. This was mixed with 40 g of water and emulsified at 12,000 rpm for 12 minutes using a homogenizer. Then, after stirring at 45 ° C. for 4 hours, 40 g of water was added, and the mixture was filtered with a filter cloth. The mixture was further stirred at 45 ° C. for 40 hours to obtain polymer particles P-2. The average particle size of the dispersion liquid of polymer particles P-2 was 0.22 μm.

<Preparation of support>
In order to remove rolling oil on the surface of an aluminum plate (material: JIS A 1050) having a thickness of 0.3 mm, a 10% by mass aqueous sodium aluminate solution was subjected to a degreasing treatment at 50 ° C. for 30 seconds. The aluminum plate surface was grained using ^three 3 mm bundled nylon brushes and a Pumice-water suspension (specific gravity: 1.1 g / cm ³ ) having a median diameter of 25 μm, and thoroughly washed with water. The aluminum plate was etched by immersing it in a 25% by mass aqueous solution of sodium hydroxide at 45 ° C. for 9 seconds, washed with water, and further immersed in a 20% by mass aqueous solution of nitric acid at 60 ° C. for 20 seconds and washed with water. The amount of etching on the grained surface was about 3 g / m ² .

Next, an electrochemical surface roughening treatment was continuously performed using an AC voltage of 60 Hz. The electrolytic solution was a 1% by mass aqueous solution of nitric acid (containing 0.5% by mass of aluminum ions), and the temperature of the solution was 50 ° C. The AC power supply waveform is an electrochemical roughening process using a trapezoidal rectangular wave alternating current with a time TP from a current value reaching zero to a peak to a peak value of 0.8 msec, a duty ratio of 1: 1 and a carbon electrode as a counter electrode. Was done. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak value of the current, and 5% of the current flowing from the power supply was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was an anode. Thereafter, water washing by spraying was performed.

Subsequently, nitric acid electrolysis was performed using a 0.5% by mass aqueous solution of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution at a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was an anode. Electrochemical surface roughening treatment was performed in the same manner as described above, and then water washing was performed by spraying.
Next, a DC anodized film of 2.5 g / m ² was formed on an aluminum plate at a current density of 15 A / dm ^{2 using a} 15% by mass aqueous solution of sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolytic solution, and then washed with water. After drying, a support was prepared. The average pore diameter (surface average pore diameter) in the surface layer of the anodized film was 10 nm.
The pore diameter in the surface layer of the anodic oxide film was measured using an ultra-high resolution type SEM (S-900 manufactured by Hitachi, Ltd.) at a relatively low accelerating voltage of 12 V and a vapor deposition treatment for imparting conductivity. Without application, the surface was observed at a magnification of 150,000 times, and 50 pores were randomly extracted to obtain an average value. The standard deviation error was less than ± 10%.

<Formation of undercoat layer>
The undercoat layer coating solution (1) having the following composition was applied on the support so that the dry coating amount was 20 mg / m ² to form an undercoat layer.

<Undercoat layer coating liquid (1)>
・ Polymer P-1 (the following structure): 0.18 parts ・ Hydroxyethyliminodiacetic acid: 0.10 parts ・ Water: 61.4 parts

法 The synthesis method of the polymer P-1 is described below.

(Synthesis of Monomer M-1)
200 g (0.91 mol) of Ancamine 1922A (diethylene glycol di (aminopropyl) ether, manufactured by Air Products), 435 g of distilled water and 410 g of methanol were added to a 3 L three-necked flask and cooled to 5 ° C. Next, 222.5 g (1.82 mol) of benzoic acid and 25 mg (0.15 mmol) of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO) were added, and methacrylic acid was added. 280 g (1.82 mmol) of the anhydride was added dropwise so that the internal temperature of the reaction solution became 10 ° C. or less. The reaction solution was stirred at 5 ° C. for 6 hours, then at 25 ° C. for 12 hours, and adjusted to pH 3.3 by adding 70 g of phosphoric acid. The reaction solution was transferred to a 10 L stainless steel beaker, 3.7 L of ethyl acetate, 1.5 L of methyl-tertbutyl ether (MTBE) and 0.65 L of distilled water were added, and the mixture was stirred vigorously and allowed to stand. After discarding the upper layer (organic layer), 1.8 L of ethyl acetate was added, and the mixture was vigorously stirred and allowed to stand, and the upper layer was discarded. Further, 1.5 L of ethyl acetate was added, and the mixture was vigorously stirred and allowed to stand, and the upper layer was discarded. Next, 1.6 L of MTBE was added, and the mixture was vigorously stirred and allowed to stand, and the upper layer was discarded. 62.5 mg (0.36 mmol) of 4-OH-TEMPO was added to the obtained aqueous solution to obtain 1.2 kg of an aqueous solution of monomer M-1 (20.1% by mass in terms of solid content).

(Purification of monomer M-2)
420 g of light ester P-1M (2-methacryloxyethyl acid phosphate, manufactured by Kyoeisha Chemical Co., Ltd.), 1,050 g of diethylene glycol dibutyl ether and 1,050 g of distilled water were added to a separating funnel, and the mixture was vigorously stirred and allowed to stand. . After discarding the upper layer, 1,050 g of diethylene glycol dibutyl ether was added, and the mixture was stirred vigorously and allowed to stand. The upper layer was discarded to obtain 1.3 kg of an aqueous solution of monomer M-2 (10.5% by mass in terms of solid content).

(Synthesis of Polymer P-1)
600.6 g of distilled water, 33.1 g of an aqueous solution of monomer M-1 and 46.1 g of the following monomer M-3 were added to a 3 L three-necked flask, and the temperature was raised to 55 ° C. under a nitrogen atmosphere. Next, a dropping solution A shown below was added dropwise over 2 hours, stirred for 30 minutes, 3.9 g of VA-046B (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the temperature was raised to 80 ° C. Stirred for .5 hours. After the reaction solution was returned to room temperature (25 ° C., the same applies hereinafter), 175 g of a 30% by mass aqueous sodium hydroxide solution was added to adjust the pH to 8.3. Next, 152.2 mg of 4-OH-TEMPO was added, and the temperature was raised to 53 ° C. 66.0 g of methacrylic anhydride was added, and the mixture was stirred at 53 ° C for 3 hours. After returning to room temperature, the reaction solution was transferred to a 10 L stainless steel beaker, 1,800 g of MTBE was added, and the mixture was vigorously stirred and allowed to stand, and the upper layer was discarded. Similarly, the washing operation with 1,800 g of MTBE was further repeated twice, and 1,700 g of distilled water and 212 mg of 4-OH-TEMPO were added to the obtained aqueous layer to obtain a uniform solution of polymer P-1 (solid content: 11%). 4.1%). The weight average molecular weight (Mw) in terms of polyethylene glycol by gel permeation chromatography (GPC) was 200,000.

-Drip liquid A-
-Aqueous solution of the above monomer M-1: 132.4 g
-The above monomer M-2 aqueous solution: 376.9 g
-Monomer M-3 [the following structure]: 184.3 g
・ Blemmer PME4000 (manufactured by NOF Corporation): 15.3 g
・ VA-046B (manufactured by Wako Pure Chemical Industries, Ltd.): 3.9 g
・ Distilled water: 717.4 g

Blemmer PME4000: methoxypolyethylene glycol methacrylate (number of repeating oxyethylene units: 90)
VA-046B: 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate

<Preparation of coating solution for image recording layer>
According to the amounts used in Table 1, each component was added, and a solvent was added and mixed so that the solid content concentration became 7.0% by mass, to thereby prepare coating solutions for image recording layers of Comparative Examples. . The amount (parts by mass) of each material shown in Table 1 is the solid content.

<Preparation of protective layer coating solution>
-Inorganic layered compound dispersion (1) [described below]: 1.5 parts-Polyvinyl alcohol (CKS50, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., modified with sulfonic acid, saponification degree 99 mol% or more, polymerization degree 300) 6 mass% Aqueous solution: 0.55 part ・ Polyvinyl alcohol (PVA-405, manufactured by Kuraray Co., Ltd., saponification degree: 81.5 mol%, polymerization degree: 500) 6% by mass Aqueous solution: 0.03 part ・ Surfactant (polyoxyethylene lauryl) Ether, Emarex 710, manufactured by Nippon Emulsion Co., Ltd.) 1% by mass aqueous solution: 0.86 parts, ion-exchanged water: 6.0 parts

(4) The method for preparing the inorganic layered compound dispersion liquid (1) used in the protective layer coating liquid is described below.

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

(Examples 1 to 16 and Comparative Examples 1 to 4)
<Preparation of lithographic printing plate precursor>
The undercoat layer coating solution having the above composition was applied on the support so that the dry coating amount was 20 mg / m ² to form an undercoat layer. An image recording layer coating solution having the composition shown in Table 1 was coated on the undercoat layer with a bar, and oven-dried at 120 ° C. for 40 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ² .
The coating solution for the image recording layer was prepared by mixing and stirring the particles immediately before coating.
When a protective layer is provided according to the description in Table 1, the protective layer coating solution having the above composition is coated on the image recording layer with a bar, and oven-dried at 120 ° C. for 60 seconds to obtain a dry coating amount of 0.15 g. / M ² of the protective layer.

<Evaluation of lithographic printing plate precursor>
The lithographic printing plate precursor prepared as described above was output by Kodak Magnus 800 Quantum equipped with an infrared semiconductor laser at an output of 27 W, an external drum rotation speed of 450 rpm, and a resolution of 2,400 dpi (dot per inch, 2.5 inch for 1 inch). (Irradiation energy of 110 mJ / cm ² ). The exposure image included a solid image and a chart of 3% halftone dots of an AM screen (Amplitude Modulated Screening).

(1) On-press developability The lithographic printing plate precursor obtained by the above production method was subjected to Luxel PLATESETTER T-6000III manufactured by FUJIFILM Corporation equipped with an infrared semiconductor laser, with an outer drum rotation speed of 1,000 rpm and a laser output of 70%. Exposure was performed under conditions of a resolution of 2,400 dpi (dot per inch, 1 inch is 2.54 cm) (equivalent to irradiation energy of 110 mJ / cm ² ). The exposed image included a solid image and a 50% halftone dot chart of a 20 μm dot FM (Frequency Modulation) screen.
The exposed lithographic printing plate precursor was mounted on a plate cylinder of a printing machine LITHRONE 26 manufactured by Komori Corporation without developing. ETHITY-2 (manufactured by FUJIFILM Corporation) / tap water = 2/98 (volume ratio) using dampening water and Values-G (N) black ink (manufactured by DIC Graphics Co., Ltd.) The dampening solution and ink are supplied by the standard automatic printing start method, and 100 sheets are printed on Tokishi Art Paper (76.5 kg continuous weight) (manufactured by Mitsubishi Paper Mills) at a printing speed of 10,000 sheets per hour. Was done.
The on-press development of the unexposed portion of the image recording layer was completed on the printing press, and the number of print sheets required until ink was not transferred to the non-image portion was measured and evaluated as on-press developability. The smaller the number, the better the on-press developability. The measurement results are shown in Table 1.

(2) On-press developability over time (on-press developability over time)
After the lithographic printing plate precursor obtained by the above-mentioned manufacturing method was allowed to elapse in an oven at 60 ° C. for 7 days, the external drum rotation speed was set to 1,000 rpm by using Luxel PLATESETTER T-6000III manufactured by FUJIFILM Corporation equipped with an infrared semiconductor laser. Exposure was performed under the conditions of a laser output of 70% and a resolution of 2,400 dpi (equivalent to an irradiation energy of 110 mJ / cm ² ). The exposed image included a solid image and a 50% halftone dot chart of a 20 μm dot FM screen.
The exposed lithographic printing plate precursor was mounted on a plate cylinder of a printing machine LITHRONE 26 manufactured by Komori Corporation without developing. ETHITY-2 (manufactured by FUJIFILM Corporation) / tap water = 2/98 (volume ratio) using dampening water and Values-G (N) black ink (manufactured by DIC Graphics Co., Ltd.) Supplying fountain solution and ink by the standard automatic printing start method, printing 300 sheets on Tokishi Art Paper (76.5 kg continuous weight) (manufactured by Mitsubishi Paper Mills) at a printing speed of 10,000 sheets per hour. Was done.
The on-press development of the unexposed portion of the image recording layer was completed on the printing press, and the number of print sheets required until ink was not transferred to the non-image portion was measured and evaluated as on-press developability. The smaller the number, the better the on-press developability. The measurement results are shown in Table 1.

(3) Printing durability when using UV ink (UV ink printing durability)
In the above evaluation of the on-press developability, the procedure was the same except that the Value-G (N) black ink was changed to a UV ink (T & K UV OFS K-HS Black GE-M (manufactured by T & K TOKA)). After the evaluation of the on-press developability, printing was further continued. As the number of prints was increased, the image area gradually became worn, and the ink density on the printed matter was reduced. The number of prints is defined as the number of copies when the value obtained by measuring the dot area ratio of the 3% halftone dot of the AM screen with a Gretag densitometer (manufactured by GretagMacbeth) by 1% from the measured value of the 500th print is defined as the number of printed sheets. The printing durability was evaluated. The evaluation was made based on the relative printing durability when the number of printed sheets was 50,000, with 100 being the value. The higher the value, the better the printing durability. The evaluation results are shown in Table 1.
Relative printing durability = (number of target lithographic printing plate precursors printed) / 50,000 × 100

Table 1 summarizes the evaluation results.

結果 From the results shown in Table 1, it can be seen that the planographic printing plate precursors of Examples 1 to 16 are superior to the planographic printing plate precursors of Comparative Examples in UV ink printing durability of the obtained planographic printing plates. Furthermore, it can be seen that the planographic printing plate precursors of Examples 1 to 16 also have good on-press developability and aging on-press developability.

Details of the compounds described in Table 1 other than those described above are shown below.
<Monomer>
-Radical polymerizable monomer-
RM-1: Tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.)
RM-2: dipentaerythritol pentaacrylate (SR-399, manufactured by Sartomer)
RM-3: dipentaerythritol hexaacrylate (A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd.)
RM-4: dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer (UA-510H, manufactured by Kyoeisha Chemical Co., Ltd.)
RM-5: Ethoxylated pentaerythritol tetraacrylate (ATM-4E, manufactured by Shin-Nakamura Chemical Co., Ltd.)

<Polymerization initiator (polymerization initiator that generates both radicals and acids)>
I-1 to I-5: Compounds having the following structures

<Infrared absorber>
K-1 to K-3: compounds having the following structures

中 In the above structure, Ph represents a phenyl group.

<Radical generation aid>
R-1: The following compound

<Acid colorant>
H-1: S-205 (manufactured by Fukui Yamada Chemical Industry Co., Ltd.)
H-2: GN-169 (manufactured by Yamamoto Kasei Co., Ltd.)
H-3: Black-XV (manufactured by Yamamoto Kasei Co., Ltd.)
H-4: Red-40 (manufactured by Yamamoto Kasei Co., Ltd.)

<Hydrophilic compound>
T-1: Tris (2-hydroxyethyl) isocyanurate T-2: Compound having the following structure T-3: Hydroxypropylcellulose (Klucel M, manufactured by Hercules)

(Degreasing agent)
C-1: Compound having the following structure C-2: Benzyldimethyloctylammonium PF ₆ salt C-3: Compound having the following structure (Mw = 20,000)

<Surfactant>
W-1: The following compound

添 In the above structure, the subscript at the lower right of the parenthesis of each structural unit indicates the content ratio (mass ratio).

<Solvent>
S-1: 2-butanone (MEK)
S-2: 1-methoxy-2-propanol (MFG)
S-3: methanol S-4: 1-propanol S-5: distilled water

The disclosure of Japanese Patent Application No. 2018-182229 filed on September 27, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards referred to in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

Claims

Having an image recording layer on the support,
A lithographic printing plate precursor wherein the image recording layer comprises a polymerization initiator that generates both a radical and an acid, a compound having a radically polymerizable group, a compound having a cationically polymerizable group, and an infrared absorber.
平 The lithographic printing plate precursor according to claim 1, wherein the polymerization initiator is a compound having a salt structure.
3. The lithographic printing plate precursor according to claim 2, wherein the polymerization initiator is a compound having an onium salt structure.
4. The lithographic printing plate precursor according to claim 2, wherein the pKa of the counter anion having the salt structure in the polymerization initiator is -5 or less.
The compound having a radical polymerizable group includes a binder polymer having a radical polymerizable group,
The lithographic printing plate precursor according to any one of claims 1 to 4, wherein the compound having a cationically polymerizable group includes a binder polymer having a cationically polymerizable group.
The compound having a radical polymerizable group includes a monomer having a radical polymerizable group,
The lithographic printing plate precursor according to any one of claims 1 to 4, wherein the compound having a cationically polymerizable group contains a monomer having a cationically polymerizable group.
5. The compound according to claim 1, wherein the compound having a radical polymerizable group and the compound having a cationic polymerizable group include particles containing a monomer having a radical polymerizable group and a monomer having a cationic polymerizable group. The lithographic printing plate precursor according to any one of the preceding items.
The compound having a radical polymerizable group includes a binder polymer having a radical polymerizable group and a monomer having a radical polymerizable group,
The lithographic printing plate precursor according to claim 5, wherein the compound having a cationically polymerizable group includes a binder polymer having a cationically polymerizable group and a monomer having a cationically polymerizable group.
As the compound having the radical polymerizable group, and the compound having the cationic polymerizable group,
A monomer having a radical polymerizable group,
A monomer having a cationically polymerizable group, and
The lithographic printing plate precursor according to claim 6 or 7, further comprising particles containing a monomer having a radically polymerizable group and a monomer having a cationically polymerizable group.
As the compound having the radical polymerizable group, and the compound having the cationic polymerizable group,
A binder polymer having a radical polymerizable group,
A monomer having a radical polymerizable group,
A binder polymer having a cationically polymerizable group,
A monomer having a cationically polymerizable group, and
The lithographic printing plate precursor according to claim 8 or 9, comprising particles containing a monomer having a radical polymerizable group and a monomer having a cationic polymerizable group.
The lithographic printing plate precursor according to any one of claims 1 to 10, which is an on-press development type lithographic printing plate precursor.
A step of exposing the lithographic printing plate precursor according to any one of claims 1 to 11 imagewise to form an exposed portion and an unexposed portion, and
A method for preparing a lithographic printing plate, comprising a step of supplying at least one of a printing ink and a dampening solution to remove the unexposed portion.