WO2015045789A1

WO2015045789A1 - Lithographic printing original plate and plate making method

Info

Publication number: WO2015045789A1
Application number: PCT/JP2014/073405
Authority: WO
Inventors: 昭太鈴木
Original assignee: 富士フイルム株式会社
Priority date: 2013-09-30
Filing date: 2014-09-04
Publication date: 2015-04-02

Abstract

Provided are: a lithographic printing original plate which has an image recording layer that contains (A) a cyanine dye represented by general formula (1), (B) a binder polymer and (C) a polymerizable monomer on a supporting body, and which provides a lithographic printing plate having excellent printing durability; and a plate making method using this lithographic printing original plate. Also provided are: a lithographic printing original plate which provides a lithographic printing plate that has excellent on-press developability and is capable of forming a color image that has good visibility even after long-term storage, while having excellent printing durability; and a plate making method using this lithographic printing original plate. In general formula (1), each of R¹ and R⁸ independently represents a hydrocarbon group; each of R², R³, R⁴, R⁵, R⁶ and R⁷ independently represents a hydrogen atom or a hydrocarbon group, and R⁴ and R⁵ may combine together to form a ring; each of Q¹ and Q² independently represents -NR⁰-, S, O, -CH=CH- or a dialkyl methylene group; R⁰ represents a hydrogen atom or a hydrocarbon group; each of T¹ and T² independently represents an atomic group necessary for forming an aromatic ring or a heteroaromatic ring; each of A^- and B^- independently represents a counter ion selected from among a halide ion, a perchlorate ion, a tetraphenyl borate ion, a tetrafluoroborate ion, a hexafluorophosphate ion and a sulfonate ion; and each of R⁹-R²² independently represents a hydrogen atom, a halogen atom or a monovalent organic group, provided that at least two of the R¹³-R²² moieties are electron-withdrawing groups selected from among a chlorine atom, a fluorine atom and a trifluoromethyl group and at least two of the R⁹-R¹² moieties are hydrocarbon groups.

Description

Planographic printing plate precursor and plate making method

The present invention relates to a lithographic printing plate precursor and a lithographic printing method using the same. Specifically, based on a digital signal from a computer or the like, for example, a lithographic printing plate capable of direct plate making by scanning with a laser beam having a wavelength of 750 to 1400 nm, for example, so-called direct plate making and containing a specific cyanine dye The present invention relates to an original plate and a plate making method by so-called on-press development in which the lithographic printing plate precursor is directly developed on a printing press without going through a development processing step.

Generally, as a pre-process for attaching a printing plate to a printing press, an operation (inspection) for inspecting and identifying an image on the printing plate is performed to check whether the printing plate has been recorded as intended. In general lithographic printing plate precursors accompanied with a development process, it is easy to confirm an image at the stage of attaching a printing plate to a printing machine after development processing by coloring an image recording layer.
However, in the case of on-press development type or unprocessed (no development) type lithographic printing plate precursor, there is no way to check the image on the printing plate precursor at the stage of attaching the printing plate precursor to the printing machine, and the plate should be identified. I can't. In particular, whether or not it is possible to determine that a register mark (register mark) that serves as a registration mark in multi-color printing is drawn is important for the printing operation. Therefore, in order to impart visibility to the on-press development type or unprocessed (no development) type lithographic printing plate precursor, there is a means for confirming an image at the stage of exposure, for example, means for coloring or decoloring the exposed area. It is requested.

An on-press development type lithographic printing plate precursor capable of forming a color image with good visibility by infrared laser exposure and having excellent on-press developability and a lithographic printing method using the same have been proposed (see Patent Document 1). However, the lithographic printing plate precursor described in Patent Document 1 has good performance immediately after production, but it has been found that when the lithographic printing plate precursor is stored over time, the visibility decreases. Further, it was found that the lithographic printing plate precursor described in Patent Document 1 has insufficient printing durability.

Japanese Unexamined Patent Publication No. 2008-191468

An object of the present invention is to provide a lithographic printing plate precursor that provides a lithographic printing plate having excellent printing durability and a plate making method using the lithographic printing plate precursor. Another object of the present invention is to provide a lithographic printing plate that has excellent on-press developability, can form a color image with good visibility even when stored over time, and provides a lithographic printing plate having excellent printing durability. An original plate and a plate making method using the planographic printing plate precursor are provided.

1. A lithographic printing plate precursor having an image recording layer containing (A) a cyanine dye represented by the following general formula (1), (B) a binder polymer and (C) a polymerizable monomer on a support.

In general formula (1), R ¹ and R ⁸ each independently represent a hydrocarbon group. R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom or a hydrocarbon group. R ⁴ and R ⁵ may be connected to each other to form a ring. Q ¹ and Q ² each independently represent —NR ⁰ —, S, O, —CH═CH—, or a dialkylmethylene group. R ⁰ represents a hydrogen atom or a hydrocarbon group. T ¹ and T ² each independently represents an atomic group necessary for forming an aromatic ring or a heteroaromatic ring. A ⁻ and B ⁻ each independently represent a counter ion selected from a halide ion, a perchlorate ion, a tetraphenylborate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion. R ⁹ to R ²² each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, provided that at least two of R ¹³ to R ²² are selected from a chlorine atom, a fluorine atom and a trifluoromethyl group. It is an electron withdrawing group, and at least two of R ⁹ to R ¹² are hydrocarbon groups having 1 to 3 carbon atoms.
2. The (A) cyanine dye is a cyanine dye represented by the following general formula (2): The lithographic printing plate precursor described in 1.

In general formula (2), R ¹ , R ² , R ³ , R ⁶ , R ⁷ , R ⁸ , T ¹ , T ² , A ⁻ and B ⁻ are R ¹ , R ² in general formula (1), respectively. , R ³ , R ⁶ , R ⁷ , R ⁸ , T ¹ , T ² , A ⁻ and B ⁻ . R ⁹ to R ²² each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, provided that at least two of R ¹³ to R ²² are electrons selected from a chlorine atom, a fluorine atom and a trifluoromethyl group. It is an attractive group, and at least two of R ⁹ to R ¹² are hydrocarbon groups having 1 to 3 carbon atoms.

3. 1. In the cyanine dye represented by the general formula (2), at least two of R ¹³ to R ²² are chlorine atoms. The lithographic printing plate precursor described in 1.
4). 1. In the cyanine dye represented by the general formula (2), each of R ⁹ and R ¹¹ is a hydrocarbon group having 1 to 3 carbon atoms. Or 3. The lithographic printing plate precursor described in 1.
5. The image recording layer further contains a borate compound. ~ 4. The lithographic printing plate precursor as described in any one of the above.
6). 4. The borate compound is a tetraphenylborate salt The lithographic printing plate precursor described in 1.
7). 1. The image recording layer further contains polymer fine particles. ~ 6. The lithographic printing plate precursor as described in any one of the above.
8). 1. having a protective layer on the image recording layer; ~ 7. The lithographic printing plate precursor as described in any one of the above.

9. 7. The protective layer contains an inorganic stratiform compound The lithographic printing plate precursor described in 1.
10. (B) The binder polymer has an alkylene oxide group. ~ 9. The lithographic printing plate precursor as described in any one of the above.
11. 1. The unexposed portion of the image recording layer can be removed by at least one of dampening water and printing ink. ~ 10. The lithographic printing plate precursor as described in any one of the above.
12.11. A lithographic printing plate precursor as described in 1), image-exposing with an infrared laser, and then removing an unexposed portion of the image recording layer on a printing machine with at least one of dampening water and printing ink.

Although the action mechanism of the present invention is not sufficiently clear, it is estimated as follows.
The cyanine dye represented by the general formula (1) according to the present invention is composed of an infrared absorber skeleton and a radical generator skeleton having a sulfonium salt structure, and has both infrared absorption ability and radical generation ability in one molecule. In the cyanine dye represented by the general formula (1), electron transfer or energy transfer is efficiently performed in the radical generator skeleton having a sulfonium salt structure by infrared laser exposure, and as a result, radicals are generated and coexist (C). In addition to initiating the polymerization reaction of the polymerizable monomer, a color change occurs due to the structural change of the cyanine dye.
In particular, in the cyanine dye represented by the general formula (1) according to the present invention, at least two of R ¹³ to R ²² in the radical generator skeleton are specific electron-attracting groups and at least R ⁹ to R ¹² are used. It has a structural feature that two are hydrocarbon groups. This structural feature greatly improves the efficiency of electron transfer or energy transfer by infrared exposure, and the generated radicals promote the polymerization reaction of the polymerizable monomer, resulting in the formation of a high-strength cured image, resulting in excellent resistance. It is thought that printability can be obtained.
Further, due to the structural features of the radical generator skeleton, the energy level is appropriately adjusted between the infrared absorber skeleton and the radical generator skeleton having a sulfonium salt structure, and in addition, at least one of R ⁹ to R ¹² Since the two are hydrocarbon groups, decomposition of the radical generator skeleton due to moisture and the like is suppressed, and the storage stability of the cyanine dye itself represented by the general formula (1) is improved. As a result, the lithographic printing plate precursor It is considered that a color image with good visibility can be formed even when stored for a long time.

According to the present invention, a lithographic printing plate precursor that provides a lithographic printing plate having excellent printing durability and a plate making method using the lithographic printing plate precursor can be provided. Also, a lithographic printing plate precursor that provides a lithographic printing plate having excellent on-press developability and capable of forming a color image with good visibility even when stored over time, and also providing excellent printing durability, and the lithographic printing plate A plate making method using an original plate can be provided.

[Lithographic printing plate precursor]
The lithographic printing plate precursor according to the invention is described in detail below. The lithographic printing plate precursor according to the invention has an image recording layer containing (A) a cyanine dye represented by the following general formula (1), (B) a binder polymer, and (C) a polymerizable monomer on a support. .

In general formula (1), R ¹ and R ⁸ each independently represent a hydrocarbon group. R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom or a hydrocarbon group. R ⁴ and R ⁵ may be connected to each other to form a ring. Q ¹ and Q ² each independently represent —NR ⁰ —, S, O, —CH═CH—, or a dialkylmethylene group. R ⁰ represents a hydrogen atom or a hydrocarbon group. T ¹ and T ² each independently represents an atomic group necessary for forming an aromatic ring or a heteroaromatic ring. A ⁻ and B ⁻ each independently represent a counter ion selected from a halide ion, a perchlorate ion, a tetraphenylborate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion. R ⁹ to R ²² each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, provided that at least two of R ¹³ to R ²² are selected from a chlorine atom, a fluorine atom and a trifluoromethyl group. It is an electron withdrawing group, and at least two of R ⁹ to R ¹² are hydrocarbon groups having 1 to 3 carbon atoms.

In the lithographic printing plate precursor according to the invention, an undercoat layer can be provided between the support and the image recording layer, and a protective layer can be provided on the image recording layer, if necessary.
Hereinafter, components of the planographic printing plate precursor according to the present invention will be described.

(Image recording layer)
The image recording layer of the lithographic printing plate precursor according to the invention comprises (A) a cyanine dye represented by the general formula (1) (hereinafter also referred to as a specific cyanine dye), (B) a binder polymer, and (C) a polymerizable monomer. Containing.

(A) Specific cyanine dye The specific cyanine dye absorbs infrared rays to be in an excited state, causes electron transfer to occur in the sulfonium salt structure in the molecule, and releases a radical that functions as a polymerization initiator. On the other hand, the specific cyanine dye itself undergoes a structural change and a hue change occurs. The specific cyanine dye preferably has a maximum absorption wavelength in a wavelength range of 750 nm to 1400 nm, and particularly preferably a cyanine dye having a maximum absorption wavelength in a wavelength range of 750 nm to 900 nm.

In the general formula (1), the hydrocarbon group represented by R ¹ or R ⁸ may have a substituent, and preferably has 20 or less carbon atoms. Preferred examples of the substituent include an alkoxy group having 12 or less carbon atoms, an aryloxy group, a carboxyl group, a sulfo group, an alkylcarbonyloxy group, and an aryloxycarbonyl group.
R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are hydrogen atoms, or R ² , R ³ , R ⁶ and R ⁷ are hydrogen atoms, and R ⁴ and R ⁵ are connected to each other. To form a ring.
The ring formed by connecting R ⁴ and R ⁵ to each other is preferably a 5-membered or 6-membered ring. From the viewpoint of improving visibility, it is preferable to form a 5-membered ring.
In —NR ⁰ — represented by Q ¹ or Q ² , the hydrocarbon group represented by R ⁰ may have a substituent, and preferably has 20 or less carbon atoms. Preferred examples of the substituent include a halogen atom, an amino group, an alkoxy group, an aryloxy group, a carboxy group, a sulfo group, an alkylcarbonyloxy group, and an aryloxycarbonyl group.
The aromatic ring or heteroaromatic ring formed by T ¹ or T ² may have a substituent. Preferred aromatic rings include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned, for example. From the viewpoint of improving visibility, an electron donating group is preferable, and specifically, an alkoxy group having 12 or less carbon atoms or an alkyl group having 12 or less carbon atoms is preferable.
A ^- or B ^- Counter represented by ion is a counter ion which exists when necessary charge neutralization at a particular cyanine dye. The counter ion is preferably tetrafluoroborate ion or hexafluorophosphate ion from the viewpoint of improving visibility and printing durability.
Specific examples of the hydrocarbon group having 1 to 3 carbon atoms represented by at least two of R ⁹ to R ¹² include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

The monovalent organic group represented by any one of R ⁹ to R ²² preferably has 12 or less carbon atoms. Specifically, for example, amino group, substituted amino group, substituted carbonyl group, hydroxyl group, substituted oxy group, thiol group, thioether group, silyl group, nitro group, cyano group, alkyl group, alkenyl group, aryl group, heterocyclic ring Group, sulfo group, substituted sulfonyl group, sulfonato group, substituted sulfinyl group, phosphono group, substituted phosphono group, phosphonato group, and substituted phosphonato group. If possible, they may further have a substituent. For details of the monovalent organic group represented by any of R ⁹ to R ²² , reference can be made to the description of paragraph numbers [0052] to [0077] of JP-A-2008-191468.
From the viewpoint of improving visibility and printing durability, among R ⁹ to R ²² , at least two of R ⁹ to R ¹² are hydrocarbon groups having 1 to 3 carbon atoms, and at least two of R ¹³ to R ²² are chlorine atoms. , An electron withdrawing group selected from a fluorine atom and a trifluoromethyl group, and other R ⁹ to R ²² are preferably hydrogen atoms.

In the general formula (1), R ⁴ and R ⁵ preferably form a 5-membered ring from the viewpoint of visibility and printing durability, Q ¹ and Q ² are dialkylmethylene groups, and T ¹ Alternatively, the ring formed by T ² is preferably an aromatic ring.
In particular, at least two of R ¹³ to R ²² are preferably chlorine atoms, and R ⁹ and R ¹¹ are preferably hydrocarbon groups having 1 to 3 carbon atoms. More preferably, at least two of R ¹³ to R ²² are chlorine atoms, and R ⁹ and R ¹¹ are hydrocarbon groups having 1 to 3 carbon atoms.

Among the cyanine dyes represented by the general formula (1), a cyanine dye represented by the following general formula (2) is particularly preferable.

In the general formula (2), from the viewpoint of visibility and printing durability, the ring formed by T ¹ or T ² is preferably an aromatic ring, and the aromatic ring is an electron donating group such as a methyl group. More preferably it is substituted.
In general formula (2), among R ⁹ to R ²² , at least two of R ⁹ to R ¹² are hydrocarbon groups having 1 to 3 carbon atoms, and at least two of R ¹³ to R ²² are chlorine atoms, fluorine It is an electron withdrawing group selected from an atom and a trifluoromethyl group, and other R ⁹ to R ²² are preferably hydrogen atoms.
In particular, at least two of R ¹³ to R ²² are preferably chlorine atoms, and R ⁹ and R ¹¹ are preferably hydrocarbon groups having 1 to 3 carbon atoms. More preferably, at least two of R ¹³ to R ²² are chlorine atoms, and R ⁹ and R ¹¹ are hydrocarbon groups having 1 to 3 carbon atoms.
The hydrocarbon group having 1 to 3 carbon atoms represented by R ⁹ and R ¹¹ is particularly preferably a hydrocarbon group having 3 carbon atoms. Further, it is particularly preferable that at least four of R ¹³ to R ²² are chlorine atoms.

The specific cyanine dye can be easily produced by referring to, for example, the method described in JP-A-2008-191468.

In the following, preferred specific examples of the specific cyanine dye are listed, but the present invention is not limited thereto.

The specific cyanine dye may be used alone or in combination of two or more, or may be used in combination with other infrared absorbers such as pigments and dyes. As the dye, compounds described in paragraph numbers [0059] to [0086] of JP-A-2008-195018 are preferable. As the pigment, compounds described in paragraph numbers [0072] to [0076] of JP-A-2008-195018 are preferable.

The content of the specific cyanine dye is preferably 0.05 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and particularly preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the total solid content of the image recording layer. Part by mass.

(B) Binder polymer The image recording layer in the invention contains a binder polymer in order to impart film properties. As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation as long as they can impart film properties. The binder polymer may be, for example, a linear polymer or a star-shaped polymer as described in JP-A-2007-249036.

For the image recording layer of the lithographic printing plate precursor according to the invention, it is preferable to use a binder polymer corresponding to the developing method.

(B1) Binder polymer for alkali development The chemical structure of the binder polymer is not particularly limited, but is preferably an organic polymer having an acid group from the viewpoint of solubility in an alkaline processing solution, that is, developability, and particularly carboxylic acid or a salt thereof. An organic polymer containing is more preferred.
Examples of the binder polymer that can be used in the image recording layer of the alkali development type lithographic printing plate precursor include carboxylic acid-containing alkaline water-soluble or swellable organic polymers. Examples of such an organic polymer include addition polymers having a carboxylic acid group in the side chain, such as JP-B-59-44615, JP-B-54-34327, JP-B-58-12777, and JP-B-54-25957. JP-A-54-92723, JP-A-59-53836, JP-A-59-71048, ie, methacrylic acid copolymer, acrylic acid copolymer, itaconic acid Copolymers, crotonic acid copolymers, maleic acid copolymers, partially esterified maleic acid copolymers and the like are useful. As the binder polymer, a copolymer containing a monomer unit derived from a (meth) acrylic acid ester containing a carboxylic acid (salt) group is preferable.
Also useful are acidic cellulose derivatives having a carboxylic acid group in the side chain and those obtained by adding a cyclic acid anhydride to an addition polymer having a hydroxy group. Further, JP-B-7-120040, JP-B-7-120041, JP-B-7-120042, JP-B-8-12424, JP-A 63-287944, JP-A 63-287947, JP-A-1- Urethane resins described in Japanese Patent Nos. 271741 and 11-352691 are also useful as alkaline water-soluble or swellable binders. As the binder polymer, an acrylic resin, a methacrylic resin, or a urethane resin is preferably used.

An example of a polymer preferable as the binder polymer for alkali development is a copolymer having (a) a monomer unit containing a carboxylic acid group (including a salt thereof) and (b) a monomer unit imparting radical crosslinkability.

(A) The monomer unit containing a carboxylic acid group is not particularly limited, but the structures described in paragraph numbers [0059] to [0075] of JP-A Nos. 2002-40652 and 2005-300650 are preferable. Used.
(B) The monomer unit imparting radical crosslinkability is not particularly limited, but the structures described in paragraph numbers [0041] to [0053] of JP-A No. 2007-248863 are preferably used.

The binder polymer for alkali development may contain a monomer unit derived from an ethylenically unsaturated compound that does not contain a carboxylic acid group and does not have a property of imparting radical crosslinkability as a copolymerization component.
As such a monomer unit, a monomer unit derived from (meth) acrylic acid ester or (meth) acrylic acid amide is preferable. In particular, monomer units derived from (meth) acrylic acid amides described in paragraph numbers [0061] to [0084] of JP-A-2007-272134 are preferably used. The content of such a monomer is preferably 5 to 50 units, more preferably 5 to 35 units, and more preferably 5 to 25 units, when the total number of monomer units is 100. Further preferred.

As the binder polymer, in addition to the addition polymer composed of a combination of the above monomer units, a urethane resin having a crosslinkable group in the side chain can also be preferably used. Here, the crosslinkable group is a group capable of crosslinking the binder polymer by a chemical reaction occurring in the image recording layer when the lithographic printing plate precursor is exposed. The chemical structure is not particularly limited as long as it has such a function. For example, an ethylenically unsaturated group is preferable as a functional group capable of addition polymerization. Further, functional groups described in paragraph numbers [0130] to [0139] of JP-A No. 2007-17948 can be exemplified.

The urethane resin having a crosslinkable group in the side chain preferably used in the present invention includes (i) a diisocyanate compound, (ii) a diol compound having a carboxy group, (iii) a diisocyanate compound having a crosslinkable group, and For example, it can be obtained by polyaddition reaction of (iv) a diol compound having no carboxy group and (v) a compound having an amino group.

Examples of the compounds (i), (ii) and (iii) include those represented by the formulas (4) to (10) and specific examples described in paragraph numbers [0142] to [0167] of JP-A No. 2007-17948. The indicated compounds are mentioned. Examples of the compound (iv) include those represented by formulas (A ′), formulas (a) to (e), and formulas (11) to (11) described in paragraph numbers [0180] to [0225] of JP-A No. 2007-17948. 22) and the compounds shown in the specific examples. Examples of the compound (v) include compounds represented by formulas (31) to (32) and specific examples described in paragraphs [0227] to [0230] of JP-A No. 2007-17948. Furthermore, the urethane resin obtained by introduce | transducing a crosslinkable group by polymer reaction to the polyurethane which has a carboxy group as described in Unexamined-Japanese-Patent No. 2003-270775 can also be illustrated.

In order to maintain the developability of the image recording layer, the binder polymer used preferably has an appropriate molecular weight, and has a mass average molar mass (Mw) of 5,000 to 300 in terms of polystyrene converted by the GPC method. 20,000 is preferable, and 20,000 to 150,000 is more preferable.

The binder polymer used in the image recording layer of the alkali development type lithographic printing plate precursor can be contained in an arbitrary amount in the image recording layer, but the content of the binder polymer in the image recording layer is the same as that in the image recording layer. The content is preferably 3 to 90% by mass, more preferably 6 to 80% by mass, based on the total solid content.

(B2) Binder polymer for on-press development As the binder polymer used for the image recording layer of the on-press development type lithographic printing plate precursor, a binder polymer having an alkylene oxide group is preferable.
The binder polymer having an alkylene oxide group used in the image recording layer may have a poly (alkylene oxide) moiety in the main chain or a side chain, and may have a poly (alkylene oxide) moiety. The graft polymer in the side chain may be a block copolymer composed of a block composed of a poly (alkylene oxide) -containing repeating unit and a block composed of a (alkylene oxide) -free repeating unit.
A polyurethane resin is preferred when it has a poly (alkylene oxide) moiety in the main chain. When having a poly (alkylene oxide) moiety in the side chain, the main chain polymer is acrylic resin, polyvinyl acetal resin, polyurethane resin, polyurea resin, polyimide resin, polyamide resin, epoxy resin, methacrylic resin, polystyrene resin, novolac type A phenol resin, a polyester resin, a synthetic rubber, and a natural rubber are exemplified, and an acrylic resin is particularly preferable.

The alkylene oxide at the poly (alkylene oxide) moiety is preferably an alkylene oxide having 2 to 6 carbon atoms, and particularly preferably ethylene oxide or propylene oxide.
The number of repeating alkylene oxides at the poly (alkylene oxide) site is suitably 2 to 120, preferably 2 to 70, more preferably 2 to 50.
If the number of alkylene oxide repeats is 120 or less, both the printing durability due to abrasion and the printing durability due to ink acceptance are not lowered, which is preferable.

The poly (alkylene oxide) moiety is preferably contained as a side chain of the binder polymer in a structure represented by the following general formula (a). More preferably, it is contained as a side chain of the acrylic resin in a structure represented by the following general formula (a).

In general formula (a), y represents 2 to 120, R ₁ represents a hydrogen atom or an alkyl group, and R ₂ represents a hydrogen atom or an organic group.

In the general formula (a), y is preferably 2 to 70, more preferably 2 to 50. As the organic machine represented by R ₂ , an alkyl group having 1 to 6 carbon atoms is preferable, and a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, Examples thereof include t-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, cyclopentyl group, and cyclohexyl group.
R ₁ is preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom. R ₂ is particularly preferably a hydrogen atom or a methyl group.

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

Examples of the residue having the ethylenically unsaturated bond (the above R) include-(CH ₂ ) _n CR ¹ = CR ² R ³ ,-(CH ₂ O) _n CH ₂ CR ¹ = CR ² R ³ ,- (CH ₂ CH ₂ O) _n CH ₂ CR ¹ ═CR ² R ³ , — (CH ₂ ) _n NH—CO—O—CH ₂ CR ¹ ═CR ² R ³ , — (CH ₂ ) _n —O—CO —CR ¹ ═CR ² R ³ and (CH ₂ CH ₂ O) ₂ —X (wherein R ¹ to R ³ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 20 carbon atoms, aryl R ¹ and R ² or R ³ may be bonded to each other to form a ring, n represents an integer of 1 to 10, and X represents dicyclopentadi. An enyl residue).

Specific examples of the ester residue include —CH ₂ CH═CH ₂ (described in JP-B-7-21633), —CH ₂ CH ₂ O—CH ₂ CH═CH ₂ , —CH ₂ C _{_{_{_{(CH 3) = CH 2,}}}} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 -NHCOO-CH 2 CH = CH 2 and CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

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

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

Specific examples (1) to (13) of the binder polymer used in the image recording layer of the on-press development type lithographic printing plate precursor are shown below, but the present invention is not limited thereto.
In addition, in the following exemplary compounds, a numerical value written together with each repeating unit (a numerical value written together with the main chain repeating unit) represents a mole percentage of the repeating unit. The numerical value written together with the repeating unit of the side chain indicates the number of repetitions of the repeating site.

The mass average molar mass (Mw) of the binder polymer used in the image recording layer of the on-press development type lithographic printing plate precursor is preferably 2000 or more, more preferably 5000 or more as a polystyrene conversion value by GPC method. Preferably, it is 10,000 to 300,000.

In the image recording layer, hydrophilic polymer compounds such as polyacrylic acid and polyvinyl alcohol described in JP-A-2008-195018 can be used in combination as required. Further, a lipophilic polymer compound and a hydrophilic polymer compound can be used in combination.

The form of the binder polymer may be present in the image recording layer as a binder that functions to connect each material, or may be present in the form of fine particles. When present in the form of fine particles, the average particle size is usually in the range of 10 to 1000 nm, preferably in the range of 20 to 300 nm, particularly preferably in the range of 30 to 120 nm.

The content of the binder polymer used in the image recording layer of the on-press development type lithographic printing plate precursor is preferably from 3 to 90% by mass, more preferably from 6 to 80% by mass, based on the total solid content constituting the image recording layer. preferable.

(C) Polymerizable monomer The polymerizable monomer used in the image recording layer in the invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, preferably at least one terminal ethylenically unsaturated bond. Is selected from compounds having two or more. These have chemical forms such as monomers, prepolymers, ie dimers, trimers and oligomers, or mixtures thereof.

Examples of monomers include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof, preferably unsaturated carboxylic acids. An ester of an acid and a polyhydric alcohol compound and an amide of an unsaturated carboxylic acid and a polyvalent amine compound are used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as hydroxyl group, amino group or mercapto group with monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration-condensation reaction product with carboxylic acid is also preferably used. Also, addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituents such as isocyanate groups and epoxy groups with monofunctional or polyfunctional alcohols, amines, thiols, halogen groups, tosyloxy A substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a compound in which the unsaturated carboxylic acid is replaced with unsaturated phosphonic acid, styrene, vinyl ether or the like. These are disclosed in JP-T-2006-508380, JP-A-2002-287344, JP-A-2008-256850, JP-A-2001-342222, JP-A-9-179296, JP-A-9-179297. JP-A-9-179298, JP-A-2004-294935, JP-A-2006-243493, JP-A-2002-275129, JP-A-2003-64130, JP-A-2003-280187, It is described in references including Kaihei 10-333321.

Specific examples of monomers of esters of polyhydric alcohol compounds and unsaturated carboxylic acids include acrylic acid esters such as 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. Methacrylic acid esters include 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, and the like. Specific examples of amide monomers of polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis-methacrylic. Examples include amide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide.

Also suitable are urethane-based addition-polymerizable compounds produced using an addition reaction of isocyanate and hydroxyl group. Specific examples include, for example, two or more per molecule described in JP-B-48-41708. And a vinyl urethane compound containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (A) to the polyisocyanate compound having the above isocyanate group. It is done.
_{^{_{CH 2 = C (R 4)}}} COOCH 2 CH (R 5) OH (A)
(However, R ⁴ and R ⁵ represent H or CH _3. )
Also, urethanes as described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-A-2003-344997, JP-A-2006-65210 are disclosed. Acrylates, JP-B 58-49860, JP-B 56-17654, JP-B 62-39417, JP-B 62-39418, JP-A 2000-250211, JP-A 2007-94138 Urethane compounds having an ethylene oxide-based skeleton described in Japanese Patent Publication No. 7153632, hydrophilic compounds described in US Pat. No. 7,153,632, JP-T 8-505958, JP-A 2007-293221, and JP-A 2007-293223. Urethane compounds having a group are also suitable.
Among the above compounds, tris (acryloyloxyethyl) isocyanurate, bis (acryloyloxyethyl) hydroxyethyl isocyanurate, etc. from the point of excellent balance between the hydrophilicity involved in on-press developability and the polymerization ability involved in printing durability The isocyanuric acid ethylene oxide modified acrylates are particularly preferred.

Details of the method of use such as the structure of the polymerizable monomer, whether it is used alone or in combination, and the amount added can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. The content of the polymerizable compound is preferably 0.5 to 75% by mass, more preferably 1 to 70% by mass, based on the total solid content of the image recording layer.

The image recording layer of the lithographic printing plate precursor according to the invention may contain components other than the above (A) specific cyanine dye, (B) binder polymer, and (C) polymerizable monomer.

In addition to the specific cyanine dye, the image recording layer can contain a polymerization initiator as necessary. The polymerization initiator refers to a compound that generates radicals by light, heat, or both, and initiates and accelerates polymerization of the polymerizable monomer (C). Examples of the polymerization initiator include (a) an organic halide, (b) a carbonyl compound, (c) an azo compound, (d) an organic peroxide, (e) a metallocene compound, (f) an azide compound, (g) Examples include hexaarylbiimidazole compounds, (h) borate compounds, (i) disulfone compounds, (j) oxime ester compounds, and (k) onium salt compounds, with borate compounds being particularly preferred.

Examples of the borate compound include organic borate compounds described in paragraph No. [0028] of JP-A-2008-195018.
Specific examples of the borate compound include tetraphenylborate salt, tetratolylborate salt, tetrakis (4-methoxyphenyl) borate salt, tetrakis (pentafluorophenyl) borate salt, tetrakis (3,5-bis (trifluoromethyl) phenyl ) Borate salt, tetrakis (4-chlorophenyl) borate salt, tetrakis (4-fluorophenyl) borate salt, tetrakis (2-thienyl) borate salt, tetrakis (4-phenylphenyl) borate salt, tetrakis (4-t-butylphenyl) ) Borate salt, ethyl triphenyl borate salt, butyl triphenyl borate salt and the like. From the viewpoint of achieving both printing durability, tone reproducibility, and stability over time, a tetraphenylborate salt is preferable. Examples of the counter cation of the borate compound include known cations such as alkali metal cations, alkaline earth metal cations, ammonium cations, phosphonium cations, sulfonium cations, iodonium cations, diazonium cations, and azinium cations.

In the image recording layer, polymer fine particles can be used to improve the on-press developability. In particular, polymer fine particles having a polyalkylene oxide structure are preferred. Of these, polymer fine particles having a polyalkylene oxide group in the side chain are preferred.
By using the polymer fine particles having a polyalkylene oxide structure, the permeability of the fountain solution is improved and the on-press developability is improved. As the polyalkylene oxide structure, a polyalkylene oxide structure having 2 to 120 alkylene oxide units having 2 or 3 carbon atoms is preferable, and a polyethylene oxide structure having 2 to 120 ethylene oxide units is more preferable. In particular, a polyethylene oxide structure having 20 to 100 ethylene oxide units is preferred. The fine polymer particles having a polyalkylene oxide structure can achieve both printing durability and on-press developability. Moreover, the inking property can be improved.

The polymer fine particles are preferably a hydrophobized precursor that can convert the image recording layer to be hydrophobic when heat is applied. The hydrophobized precursor polymer fine particles are preferably at least one particle selected from hydrophobic thermoplastic polymer fine particles, heat-reactive polymer fine particles, microcapsules enclosing a hydrophobic compound, and microgel (crosslinked polymer fine particles). Among these, polymer fine particles and microgels having a polymerizable group are preferable. In order to improve developability, it may have a polyalkylene oxide structure as described above.

Hydrophobic thermoplastic polymer fine particles include Research Disclosure No. 1 of January 1992. 33303, hydrophobic thermoplastic polymer fine particles described in JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250, European Patent 931647, and the like are preferable. Can be cited as a thing.
Specific examples of polymers constituting such polymer fine particles include ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, and polyalkylene structures. Mention may be made of homopolymers or copolymers of monomers such as acrylates or methacrylates or mixtures thereof. Preferable examples include a copolymer containing polystyrene, styrene and acrylonitrile, and polymethyl methacrylate.

The average particle diameter of the hydrophobic thermoplastic polymer fine particles is preferably 0.01 to 2.0 μm.

Examples of the heat-reactive polymer fine particles include polymer fine particles having a heat-reactive group, which forms a hydrophobized region by cross-linking by a heat reaction and a functional group change at that time.

The heat-reactive group in the polymer fine particle having a heat-reactive group may be any functional group that performs a reaction as long as a chemical bond is formed, but an ethylenically unsaturated group that performs a radical polymerization reaction (for example, An acryloyl group, a methacryloyl group, a vinyl group, an allyl group, etc.), a cationic polymerizable group (for example, a vinyl group, a vinyloxy group, etc.), an isocyanate group that performs an addition reaction or a block thereof, an epoxy group, a vinyloxy group, and these reactions. Functional group (for example, amino group, hydroxy group, carboxy group, etc.) having an active hydrogen atom as a partner, a carboxy group that performs a condensation reaction, a hydroxy group or amino group that is a reaction partner, an acid anhydride that performs a ring-opening addition reaction In addition, an amino group or a hydroxy group which is a reaction partner can be mentioned as a preferable one.

As the microcapsule, for example, as described in JP-A-2001-277740, JP-A-2001-277742, and EP2383118, all or part of the constituent components of the image recording layer are encapsulated in the microcapsule. It is. The constituent components of the image recording layer can also be contained outside the microcapsules. The image recording layer containing microcapsules is preferably a mode in which hydrophobic constituent components are encapsulated in microcapsules and hydrophilic constituent components are contained outside the microcapsules.

The microgel (crosslinked polymer fine particles) can contain a part of the constituent components of the image recording layer in and / or on the surface thereof, and in particular, an embodiment in which a reactive microgel is formed by having a polymerizable compound on the surface thereof. Is preferable from the viewpoint of image formation sensitivity and printing durability.

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

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

The content of the polymer fine particles is preferably 5 to 90% by mass based on the total solid content of the image recording layer.

The image recording layer of the present invention may further contain the following components as necessary.

(1) Low molecular weight hydrophilic compound The image-recording layer in the invention may contain a low molecular weight hydrophilic compound in order to improve the on-press developability without reducing the printing durability.
As the low molecular weight hydrophilic compound, for example, as the water-soluble organic compound, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like glycols and ether or ester derivatives thereof, glycerin, Polyols such as pentaerythritol and tris (2-hydroxyethyl) isocyanurate, organic amines such as triethanolamine, diethanolamine and monoethanolamine and salts thereof, organic sulfones such as alkylsulfonic acid, toluenesulfonic acid and benzenesulfonic acid Acids and salts thereof, organic sulfamic acids such as alkylsulfamic acid and salts thereof, organic sulfuric acids such as alkylsulfuric acid and alkylethersulfuric acid and salts thereof, 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.

Among these, it is preferable to contain at least one selected from polyols, organic sulfates, organic sulfonates, and betaines.

Examples of organic sulfonates include alkyl sulfonates such as sodium n-butyl sulfonate, sodium n-hexyl sulfonate, sodium 2-ethylhexyl sulfonate, sodium cyclohexyl sulfonate, sodium n-octyl sulfonate; Sodium 11-trioxapentadecane-1-sulfonate, sodium 5,8,11-trioxaheptadecane-1-sulfonate, sodium 13-ethyl-5,8,11-trioxaheptadecane-1-sulfonate, Alkyl sulfonates containing ethylene oxide chains such as sodium 5,8,11,14-tetraoxatetracosane-1-sulfonate; sodium benzenesulfonate, sodium p-toluenesulfonate, sodium p-hydroxybenzenesulfonate Sodium p-styrenesulfonate, sodium dimethyl-5-sulfonate, sodium 1-naphthylsulfonate, sodium 4-hydroxynaphthylsulfonate, disodium 1,5-naphthalenedisulfonate, 1,3,6-naphthalenetri Aryl sulfonates such as trisodium sulfonate, compounds described in paragraphs [0026] to [0031] of JP 2007-276454 A, and paragraphs [0020] to [0047] of JP 2009-154525 A Etc. The salt may be a potassium salt or a lithium salt.

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

As the betaines, compounds in which the hydrocarbon substituent on the nitrogen atom has 1 to 5 carbon atoms are preferable. Specific examples include trimethylammonium acetate, dimethylpropylammonium acetate, 3-hydroxy-4-trimethyl. Ammonioobylate, 4- (1-pyridinio) butyrate, 1-hydroxyethyl-1-imidazolioacetate, trimethylammonium methanesulfonate, dimethylpropylammonium methanesulfonate, 3-trimethylammonio-1-propanesulfonate, And 3- (1-pyridinio) -1-propanesulfonate.

Since low molecular weight hydrophilic compounds have a small hydrophobic part structure and almost no surface activity, dampening water penetrates into the exposed part of the image recording layer (image part), reducing the hydrophobicity and film strength of the image part. The ink receptivity and printing durability of the image recording layer can be maintained well.

A low molecular weight hydrophilic compound may be used independently and may be used in mixture of 2 or more types.
The amount of the low molecular weight hydrophilic compound added to the image recording layer is preferably 0.5 to 20% by mass, more preferably 1 to 15% by mass, and still more preferably 2 to 2%, based on the total solid content of the image recording layer. 10% by mass. In this range, good on-press developability and printing durability can be obtained.

(2) Grease-sensitizing agent The image-recording layer can contain a oil-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. In particular, when the lithographic printing plate precursor has a protective layer containing an inorganic stratiform compound, these compounds function as a surface coating agent for the inorganic stratiform compound, and decrease in the inking property during printing by the inorganic stratiform compound. To prevent.

Examples of the phosphonium compound include 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) butanedi (hexafluorophosphate), 1,7-bis (tri Phenylphosphonio) heptane sulfate, 1,9-bis (triphenylphosphonio) nonane = naphthalene-2,7-disulfonate, and the like.

Examples of nitrogen-containing low molecular weight compounds include amine salts and quaternary ammonium salts. Also included are imidazolinium salts, benzoimidazolinium salts, pyridinium salts, and quinolinium salts. Of these, quaternary ammonium salts and pyridinium salts are preferable. Specific examples include tetramethylammonium = hexafluorophosphate, tetrabutylammonium = hexafluorophosphate, dodecyltrimethylammonium = p-toluenesulfonate, benzyltriethylammonium = hexafluorophosphate, benzyldimethyloctylammonium = hexafluorophosphate. Fert, benzyldimethyldodecyl ammonium = hexafluorophosphate, described in paragraph numbers [0021] to [0037] of JP-A-2008-284858 and paragraph numbers [0030] to [0057] of JP-A-2009-90645 Compound etc. are mentioned.

The ammonium group-containing polymer may be any polymer as long as it has an ammonium group in its structure, but is preferably a polymer containing 5 to 80 mol% of (meth) acrylate having an ammonium group in the side chain as a copolymerization component. Specific examples include the polymers described in paragraphs [0089] to [0105] of JP2009-208458A.

The ammonium salt-containing polymer preferably has a reduced specific viscosity (unit: ml / g) determined by the following measurement method of 5 to 120, more preferably 10 to 110, particularly 15 to 100. preferable. When the reduced specific viscosity is converted into a mass average molar mass (Mw) in terms of polystyrene by GPC method, it is preferably 10,000 to 150,000, more preferably 17,000 to 140000, and particularly preferably 20000 to 130,000.

<Measurement method of reduced specific viscosity>
Weigh 1 g of polymer solids into a 20 ml volumetric flask and make up with N-methylpyrrolidone. This solution is allowed to stand for 30 minutes in a thermostatic bath at 30 ° C., put in an Ubbelohde reduced specific viscosity tube (viscosity constant = 0.010 cSt / s), and the time for flowing down at 30 ° C. is measured. The measurement is performed twice with the same sample, and the average value is calculated. Similarly, in the case of a blank (only N-methylpyrrolidone), the reduced specific viscosity (ml / g) is calculated from the following formula.

Specific examples of the ammonium group-containing polymer are shown below.
(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 6. (0000) (5) 2- (Trimethylammonio) Eth Methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40/60 Mw 7 million) (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-heptadecanesulfonate / 3,6-dioxaheptyl methacrylate copolymer ( Molar ratio 20/80 Mw 75,000) (9) 2- (Butyldimethyl) Ammonio) ethyl methacrylate hexafluorophosphate / 3,6-dioxaheptyl methacrylate / 2-hydroxy-3-methacryloyl oxy propyl methacrylate copolymer (molar ratio 15/80/5 Mw6.5 50,000)

The content of the sensitizer is preferably 0.01 to 30.0% by mass, more preferably 0.1 to 15.0% by mass, and more preferably 1 to 10% by mass with respect to the total solid content of the image recording layer. Further preferred.

(3) Others As other components, surfactants, colorants, bake-out agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic fine particles, inorganic layered compounds, and sensitizing aids or chain transfer as necessary. An agent or the like can be added. Specifically, paragraph numbers [0114] to [0159] of Japanese Patent Application Laid-Open No. 2008-284817, paragraph numbers [0023] to [0027] of Japanese Patent Application Laid-Open No. 2006-091479, and US Patent Publication No. 2008/0311520. The compound and the addition amount described in paragraph [0060] are preferably used.

(Formation of image recording layer)
For example, as described in paragraph numbers [0142] to [0143] of JP-A-2008-195018, the image recording layer is prepared by dispersing or dissolving the necessary components described above in a known solvent. It is formed by coating this on a support by a known method such as bar coater coating and drying. The image recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the application, but is generally preferably 0.3 to 3.0 g / m ² . Within this range, good sensitivity and good film characteristics of the image recording layer can be obtained.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer (sometimes referred to as an intermediate layer) is preferably provided 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. Contributes to improvement. In the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, thereby preventing the heat generated by the exposure from diffusing to the support and reducing the sensitivity.

The compound used for the undercoat layer is preferably a compound having an acid group such as phosphonic acid, phosphoric acid or sulfonic acid. Further, an adsorbable group that can be adsorbed on the surface of the support and a compound having a crosslinkable group in order to improve adhesion to the image recording layer are preferred. These compounds may be low molecular weight compounds or polymers. Moreover, you may use these compounds in mixture of 2 or more types as needed.

In the case of 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 support surface include phenolic hydroxy group, carboxyl group, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ —, —COCH ₂ COCH ₃ Is preferred. As the hydrophilic group, a sulfo group is preferable. The crosslinkable group is preferably a methacryl group or an allyl group. The polymer may have a crosslinkable group introduced by salt formation between a polar substituent of the polymer, a substituent having a counter charge and a compound having an ethylenically unsaturated bond, or a monomer other than the above, preferably May be further copolymerized with a hydrophilic monomer.
Specifically, a silane coupling agent having an ethylenic double bond reactive group capable of addition polymerization described in JP-A No. 10-282679 and an ethylenic compound described in JP-A No. 2-304441. The phosphorus compound which has a heavy bond reactive group is mentioned suitably. The crosslinkable groups described in JP-A-2005-238816, JP-A-2005-125649, JP-A-2006-239867, JP-A-2006-215263, and JP-A-2011-24584 (preferably an ethylenic group) Saturated bonding groups), those containing a low molecular compound or polymer having a functional group interacting with the support surface and a hydrophilic group are also preferably used. More preferably, it has an adsorptive group, a hydrophilic group, and a crosslinkable group that can be adsorbed on the surface of the support described in JP-A No. 2005-125749, JP-A No. 2006-188038, and JP-A No. 2011-245846. Polymers.

The content of unsaturated double bonds in the polymer for the undercoat layer is preferably 0.1 to 10.0 mmol, particularly preferably 0.2 to 5.5 mmol, per 1 g of the polymer.
The polymer for the undercoat layer preferably has a mass average molar mass of 5000 or more, more preferably 10,000 to 300,000.

The undercoat layer according to the present invention includes a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, an amino group, or a functional group having a polymerization inhibitory ability, in addition to the above-mentioned undercoat layer compound, to prevent contamination over time. And a compound having a group that interacts with the surface of an aluminum support (for example, 1,4-diazabicyclo [2,2,2] octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil) , Sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, and the like.

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

[Support]
As the support for the planographic printing plate precursor according to the invention, a known support for a planographic printing plate precursor is used. Of these, an aluminum plate that has been roughened and anodized by a known method is preferred.
In addition, the aluminum plate may be subjected to micropore enlargement treatment or sealing treatment of an anodized film described in JP-A-2001-253181 or JP-A-2001-322365, and US Pat. 714,066, 3,181,461, 3,280,734 and 3,902,734, or alkali metal silicates as described in U.S. Pat. , 276,868, No. 4,153,461 and No. 4,689,272, the surface hydrophilization treatment with polyvinylphosphonic acid as described in each specification is appropriately selected and performed. Can do.
The support preferably has a center line average roughness of 0.10 to 1.2 μm.

If necessary, the support used in the lithographic printing plate precursor is provided with an organic polymer compound described in JP-A-5-45885 on the back surface, and silicon described in JP-A-6-35174. A backcoat layer containing an alkoxy compound can be provided.

[Protective layer]
In the lithographic printing plate precursor according to the invention, a protective layer (overcoat layer) is preferably provided on the image recording layer. In addition to the function of suppressing the image formation inhibition reaction by blocking oxygen, the protective layer has a function of preventing scratches in the image recording layer and preventing ablation during high-illuminance laser exposure.
The protective layer can be formed of two or more layers. For example, the protective layer may have a two-layer structure including an upper protective layer and a lower protective layer.

The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and Japanese Patent Publication No. 55-49729. As the low oxygen permeability polymer used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used, and two or more types can be mixed and used as necessary. it can. Specific examples of the polymer include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble cellulose derivatives, poly (meth) acrylonitrile, and the like.
As the modified polyvinyl alcohol, acid-modified polyvinyl alcohol having a carboxy group or a sulfo group is preferably used. Specifically, modified polyvinyl alcohols described in JP-A-2005-250216 and JP-A-2006-259137 are preferable.
For the protective layer, a hydrophilic polymer having at least a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2) described in JP 2012-73597 A should be used. Can do.
In particular, it preferably contains a hydrophilic polymer having repeating units represented by the following general formulas (3) and (4) (hereinafter also referred to as a specific hydrophilic polymer (e)).

In General Formula (3) and General Formula (4), R ¹ and R ⁴ each independently represent a hydrogen atom or a methyl group. R ² and R ³ each independently represents a hydrogen atom, a methyl group or an ethyl group. R ⁵ represents a linear, branched or cyclic unsubstituted alkyl group or substituted alkyl group having 2 to 8 carbon atoms or a substituent represented by the following general formula (5).
Examples of the substituent that can be introduced into the substituted alkyl group include an aromatic ring group, a heterocyclic group, and a polyether group.

In the general formula (5), L represents an alkylene group having 2 to 6 carbon atoms, and R ⁶ represents a linear, branched or cyclic unsubstituted alkyl group having 4 to 8 carbon atoms or an aromatic substituted alkyl group. . n is the average number of moles of polyether added and represents a number of 2 to 4.
It is preferable that R ² and R ³ of the repeating unit represented by the general formula (3) are both hydrogen atoms. R ^{5 of the} repeating unit represented by the general formula (4) is preferably a linear, branched or cyclic unsubstituted alkyl group having 2 to 8 carbon atoms.
As a combination of the repeating units represented by the general formula (3) and the general formula (4), R ¹ and R ^{4 in} the general formula (3) and the general formula (4) are both hydrogen atoms, the general formula ( A combination in which R ² and R ^{3 in} 3) are both hydrogen atoms and R ^{5 in} formula (4) is a branched and unsubstituted alkyl group having 4 carbon atoms is particularly preferred.

The specific hydrophilic polymer (e) is preferably a hydrophilic polymer having a repeating unit represented by the following general formula (6).

In General Formula (6), R ⁷ represents a hydrogen atom or a methyl group. X is a single bond, a divalent linking group selected from the structures shown in the following structural group (1), or a divalent linking group formed by combining a plurality of selected from the structures shown in the structural group (1). To express. Y is a carboxylic acid group, a carboxylic acid group, a sulfonic acid group, a sulfonic acid group, a phosphoric acid group, a phosphoric acid group, a phosphonic acid group, a phosphonic acid group, a hydroxyl group, a carboxybetaine group, a sulfobetaine group, an ammonium group, or Represents a polyether group represented by the following general formula (7). As the repeating unit represented by the general formula (6), Y is preferably a sulfonic acid group, a sulfonic acid group, a carboxybetaine group, a sulfobetaine group, or an ammonium group from the viewpoint of water solubility and on-press development property. More preferred are groups, sulfonate groups and sulfobetaine groups.
X is preferably a linking group containing any of divalent linking chains selected from the structural group (1).

In the general formula (7), L ′ represents an alkylene group having 2 to 3 carbon atoms, and R ⁸ represents a hydrogen atom or a methyl group. n ′ is an average added mole number of the polyether and is a number of 2 to 4.

Specific examples of the monomer derived from the repeating unit represented by the general formula (3) include acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N , N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N, N-ethylmethylacrylamide, N, N-ethylmethylmethacrylamide.

Specific examples of the monomer derived from the repeating unit represented by the general formula (4) include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, i-butyl acrylate, T-butyl acrylate, pentyl acrylate, hexyl acrylate, cyclohexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, 2- (2-ethylhexyloxyethoxy) ) Ethyl, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, methacrylic acid Kurohekishiru, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, methacrylic acid decyl.

The repeating unit represented by the general formula (3) preferably contains 65 to 96.7 mol%, more preferably 70 to 80 mol%, and particularly preferably 74 to 80 mol%. The repeating unit represented by the general formula (4) preferably contains 3 to 30 mol%, more preferably 20 to 30 mol%, particularly preferably 20 to 26 mol%.

Specific examples of the monomer derived from the repeating unit represented by the general formula (6) include 2-acryloylamino-2-methyl-propanesulfonic acid, sodium 2-acryloylamino-2-methyl-propanesulfonate, -Potassium acryloylamino-2-methyl-propanesulfonate, 4-((3-methacrylamidopropyl) dimethylammonio) butane-1-sulfonate, 4-((3-acrylamidopropyl) dimethylammonio) butane-1- Sulfonate, vinyl alcohol, acrylic acid, methacrylic acid, sodium styrene sulfonate, diethylene glycol monomethyl ether methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, methacrylcholine chloride, 3-sulfomethacrylate Ropirukariumu, 2- phosphate (methacryloyloxy) ethyl, dimethyl -N- methacryloyloxyethyl -N- carboxymethyl - ammonium betaine, etc. vinylphosphonic acid.

The specific hydrophilic polymer (e) preferably contains 0.3 mol% to 5 mol% of the repeating unit represented by the general formula (6), more preferably contains 0.3 to 3 mol%, Those containing 0.3 mol% to 1.5 mol% are more preferable.
When the specific hydrophilic polymer (e) contains the repeating unit represented by the general formula (6) in the above preferable range, the lithographic printing plate precursor has better on-press developability, inking property and printing durability. Indicates.

The mass average molecular weight (Mw) of the specific hydrophilic polymer (e) as a polystyrene equivalent value by GPC method is preferably 10,000 to 200,000, more preferably 10,000 to 100,000, and 10,000 to 30. Is particularly preferred.

The content of the specific hydrophilic polymer (e) in the protective layer is preferably 40% by mass or more, more preferably 60% by mass or more, and particularly preferably 80% by mass or more of the solid content of the protective layer. Within this range, it is possible to obtain a lithographic printing plate precursor that provides a lithographic printing plate that is more excellent in on-press developability, has better inking properties, and has higher printing durability.

Specific examples of the specific hydrophilic polymer (e) are shown below. The ratio of each repeating unit is described in terms of mole fraction, and Mw is 20,000 for all.

The protective layer preferably contains an inorganic layered compound such as natural mica and synthetic mica described in JP-A-2005-119273 in order to enhance oxygen barrier properties.
The protective layer may contain a known additive such as a plasticizer for imparting flexibility, a surfactant for improving coating properties, inorganic fine particles for controlling surface slipperiness, and an ultraviolet absorber. it can. In addition, the protective layer may contain the sensitizer described for the image recording layer.

Also, adhesion to the image recording layer and scratch resistance are extremely important in handling the lithographic printing plate precursor. That is, when a hydrophilic protective layer mainly composed of a water-soluble polymer is laminated on an oleophilic image recording layer, film peeling due to insufficient adhesion is likely to occur, and the peeled part is poorly cured due to oxygen polymerization inhibition. Cause defects. On the other hand, various proposals have been made to improve the adhesion between these two layers. For example, in Japanese Patent Publication No. 54-12215 and British Patent Application No. 1303578, an acrylic emulsion or a water-insoluble vinylpyrrolidone-vinyl acetate copolymer is mixed in a protective layer in an amount of 20 to 60% by mass. Describes that sufficient adhesion can be obtained. Any of these known techniques can be applied to the protective layer in the present invention.

The protective layer is applied by a known method described in, for example, US Pat. No. 3,458,311 and JP-A-55-49729. The coating amount of the protective layer is a coating amount after drying is preferably 0.01 ~ 10g / ^{m 2,} more preferably 0.02 ~ 3g / ^{m 2,} particularly preferably 0.02 ~ 1g / ^{m 2.}

[Plate making method]
The plate making method of the lithographic printing plate precursor according to the present invention comprises at least a step of image-exposing the lithographic printing plate precursor (hereinafter also referred to as “exposure step”) and a step of developing with a processing liquid (hereinafter referred to as “development step”). Also called).

<Exposure process>
The lithographic printing plate precursor according to the invention is exposed using a light source having a wavelength of 750 nm to 1400 nm. As such a light source, a solid-state laser and a semiconductor laser emitting infrared rays are preferable, and a scanning exposure method using these infrared lasers is particularly preferable. The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like.

<Development process>
An image-exposed lithographic printing plate precursor is developed with water or a developer having a pH of 2 to 14 (developer treatment), or developed with at least one of oil-based ink and aqueous component on a printing press (on-press development). ).

Developer treatment is usually performed in the following steps. (1) Remove non-image area with developer, (2) Implement gum solution treatment, (3) Dry in drying step. The lithographic printing plate precursor according to the invention can be developed by the usual steps (normal development), but the steps (1) and (2) are preferably carried out simultaneously (simple development). In any development method, a water washing step for removing the protective layer may be performed before the step (1). The development in the step (1) is carried out according to a conventional method at a temperature of 0 to 60 ° C., preferably about 15 to 40 ° C., for example, by immersing an image-exposed lithographic printing plate precursor in a developer and rubbing with a brush, spraying By a method of spraying a developer and rubbing with a brush.

In the case of normal development, a water washing step for removing excess developer may be inserted between step (1) and step (2). Moreover, it is preferable to use a well-known alkali developing solution as a developing solution used for a process (1).

In the case of simple development, it is preferable to dry after removing the excess developer using a squeeze roller after development and gumming.
The developer used in simple development is an aqueous solution having a pH of 2 to 11. An aqueous solution containing water as a main component (containing 60% by mass or more of water) is preferable. In particular, an aqueous solution containing a surfactant (anionic, nonionic, cationic, amphoteric ion, etc.) or a water-soluble polymer compound. An aqueous solution containing is preferred. An aqueous solution containing both a surfactant and a water-soluble polymer compound is also preferred. The pH of the developer is more preferably 5 to 10.7, still more preferably 6 to 10.5, and particularly preferably 7.5 to 10.3.

In the plate making process for producing a lithographic printing plate from the lithographic printing plate precursor according to the present invention, the entire surface may be heated before exposure, during exposure, and between exposure and development, if necessary. By such heating, an image forming reaction in the image recording layer is promoted, and advantages such as improvement in sensitivity and printing durability and stabilization of sensitivity may occur. Further, for the purpose of improving the image strength and printing durability, it is also effective to subject the developed image to full surface post-heating or full surface exposure. The heating before development is usually preferably performed under mild conditions of 150 ° C. or lower. If the temperature is too high, problems such as curing of the unexposed area may occur. Very strong conditions are used for heating after development. Usually, it is in the range of 100 to 500 ° C. If the temperature is low, sufficient image reinforcing action cannot be obtained. If the temperature is too high, problems such as deterioration of the support and thermal decomposition of the image area may occur.

On-press development includes a step of supplying oil-based ink and aqueous component on a printing press without performing any development processing on the lithographic printing plate precursor after image exposure, and in the course of the printing step. An unexposed portion of the planographic printing plate precursor is removed. Image exposure may be performed on the printing machine after the planographic printing plate precursor is mounted on the printing machine, or may be separately performed using a plate setter or the like. In the latter case, the exposed lithographic printing plate precursor is mounted on the printing machine as it is without undergoing development processing. Thereafter, printing is performed by supplying oil-based ink and water-based components using a printing machine, so that the on-press development process, that is, the image recording layer in the unexposed area is removed in the initial stage of printing, and accordingly, hydrophilicity is removed. The surface of the conductive support is exposed to form a non-image part. As the oil-based ink and the aqueous component, ordinary lithographic printing ink and fountain solution are used.
The printing ink or dampening solution may be supplied to the printing plate first, but the printing ink is supplied first in order to prevent the dampening solution from being contaminated by the removed image recording layer components. Is preferred.
In this way, the lithographic printing plate precursor according to the invention is developed on the machine on an offset printing machine and used as it is for printing a large number of sheets.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto. In the polymer compound, except for those specifically defined, the molecular weight is a mass average molar mass (Mw) in terms of polystyrene converted by the GPC method, and the ratio of repeating units is a mole percentage.

[Examples 1 to 25 and Comparative Examples 1 to 4]
1. Production of on-press development type lithographic printing plate precursor (for Examples 1 to 22 and Comparative Examples 1 to 4)

<Production of support>
In order to remove rolling oil on the surface of a 0.3 mm thick aluminum plate (material JIS A 1050), after degreasing at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, the hair diameter is 0.3 mm. The surface of the aluminum plate was grained using 3 bundle-planted nylon brushes and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed thoroughly with water. Etching was performed by immersing the aluminum plate in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washing with water, and further immersed in a 20 mass% nitric acid aqueous solution at 60 ° C for 20 seconds, followed by washing with water. The etching amount of the grained surface was about 3 g / m ² .

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

Subsequently, nitric acid electrolysis was performed with an aqueous solution of 0.5% by mass of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was the anode. Electrochemical surface roughening treatment was carried out in the same manner as above, followed by washing with water by spraying.
Next, a 2.5 g / m ² direct current anodic oxide film with a current density of 15 A / dm ² is provided on an aluminum plate as an electrolyte using a 15 mass% sulfuric acid aqueous solution (containing 0.5 mass% of aluminum ions), and then washed with water. The support A was prepared by drying.
Thereafter, in order to ensure the hydrophilicity of the non-image area, the support A was subjected to silicate treatment at 60 ° C. for 10 seconds using a 2.5 mass% No. 3 sodium silicate aqueous solution, and then washed with water to obtain the support B. Produced. The adhesion amount of Si was 10 mg / m ² . The center line average roughness (Ra) of the support was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

<Formation of undercoat layer>
Next, the following coating solution (1) for the undercoat layer was applied onto the support B so that the dry coating amount was 20 mg / m ² to prepare a support having an undercoat layer.

<Coating liquid for undercoat layer (1)>
-Undercoat layer compound (1) having the following structure: 0.18 g
・ Hydroxyethyliminodiacetic acid 0.10g
・ Methanol 55.24g
・ Water 6.15g

<Formation of image recording layer>
On the undercoat layer formed as described above, the following image recording layer coating solution (1) is bar-coated, oven dried at 100 ° C. for 60 seconds, and an image recording layer having a dry coating amount of 1.0 g / m ^2. Formed.
The image recording layer coating solution (1) was prepared by mixing and stirring the following photosensitive solution and microgel solution immediately before coating.

<Photosensitive solution>
-Binder polymer (1) [the following structure] 0.240 g
-Cyanine dye represented by the general formula (1) 0.020 g
Or a compound for comparison [listed in Table 1]
・ Borate compound 0.010g
TPB [The following structure] (When added)
・ Polymerizable monomer 0.192g
Tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.)
・ Low molecular weight hydrophilic compound 0.062g
Tris (2-hydroxyethyl) isocyanurate Low molecular weight hydrophilic compound (1) [the following structure] 0.050 g
・ Fat Sensitizer 0.055g
Phosphonium compound (1) [the following structure]
・ Fat Sensitizer 0.018g
Benzyl-dimethyl-octylammonium ・ PF ₆ salt ・ Sensitizer 0.035 g
Ammonium group-containing polymer [the following structure, reduced specific viscosity 44 ml / g]
・ Fluorosurfactant (1) [The following structure] 0.008g
・ 2-butanone 1.091g
・ 1-methoxy-2-propanol 8.609g

<Microgel solution>
・ Microgel (1) 2.640 g
・ Distilled water 2.425g

The structures of the binder polymer (1), fluorine-containing surfactant (1), low molecular weight hydrophilic compound (1), phosphonium compound (1), ammonium group-containing polymer and TPB used in the photosensitive solution are as shown below. is there.

The structures of the comparative compounds R-1 to R-4 are as shown below.

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

<Formation of protective layer>
On the image recording layer, a protective layer coating solution having the following composition was further bar coated and oven dried at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.15 g / m ^2. Lithographic printing plate precursors for 1-22 and Comparative Examples 1-4 were prepared.

<Protective layer coating solution>
・ Inorganic layered compound dispersion (1) 1.5 g
-Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd. CKS50, sulfonic acid modification,
Saponification degree 99 mol% or more, polymerization degree 300) 6% by mass aqueous solution 0.55 g
・ Polyvinyl alcohol (PVA-405 manufactured by Kuraray Co., Ltd.)
Degree of saponification 81.5 mol%, degree of polymerization 500) 6% by weight aqueous solution 0.03 g
・ Polyoxyethylene lauryl ether (surfactant EMALEX 710 1 mass% aqueous solution manufactured by Nippon Emulsion Co., Ltd.) 0.86 g
・ Ion-exchanged water 6.0g

A method for preparing the inorganic layered compound dispersion (1) used in the protective layer coating solution is shown below.
<Preparation of inorganic layered compound dispersion (1)>
6.4 g of synthetic mica (Somasif ME-100, manufactured by Co-op Chemical Co., Ltd.) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed particles was 100 or more.

2. Production of on-press development type lithographic printing plate precursor (for Examples 23 to 25) Using the support having the undercoat layer used in the on-press development type lithographic printing plate precursor for Example 1 above, on this undercoat layer, An image recording layer coating liquid (2) having the following composition was applied to a bar and oven-dried at 70 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 0.6 g / m ^2. A lithographic printing plate precursor having no protective layer was prepared.

<Image recording layer coating solution (2)>
-Cyanine dye represented by the general formula (1) [described in Table 1] 0.020 g
・ Borate compound 0.010g
TPB [above structure]
-Polymer fine particle aqueous dispersion (1) (22% by mass) 10.0 g
・ Polymerizable monomer 1.50 g
SR-399 (Sartomer)
・ Mercapto-3-triazole 0.2g
・ Byk 336 (byk Chemie) 0.4g
・ KlucelM (Hercules) 4.8g
・ ELVACITE 4026 (manufactured by Ineos Acrylics)
2.5g
・ N-propanol 55.0g
・ 2-butanone 17.0g

In the image recording layer coating solution (2), the compounds described by trade names are as follows.
SR-399: Dipentaerythritol pentaacrylate Byk 336: Modified dimethylpolysiloxane copolymer (25% by mass xylene / methoxypropyl acetate solution)
・ Klucel M: Hydroxypropyl cellulose (2% by mass aqueous solution)
ELVACITE 4026: Hyperbranched polymethyl methacrylate (10% by mass 2-butanone solution)

A method for preparing the polymer fine particle aqueous dispersion (1) used in the image recording layer coating liquid (2) is shown below.
<Preparation of aqueous polymer fine particle dispersion (1)>
A 1000 ml four-necked flask was equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser, and nitrogen gas was introduced to perform deoxygenation, while polyethylene glycol methyl ether methacrylate (average of PEGMA ethylene glycol) The repeating unit was 50) 10 g, distilled water 200 g and n-propanol 200 g were added and heated until the internal temperature reached 70 ° C. Next, 10 g of premixed styrene (St), 80 g of acrylonitrile (AN) and 0.8 g of 2,2′-azobisisobutyronitrile were added dropwise over 1 hour. After the completion of the dropwise addition, the reaction was continued for 5 hours, and then 0.4 g of 2,2′-azobisisobutyronitrile was added to raise the internal temperature to 80 ° C. Subsequently, 0.5 g of 2,2′-azobisisobutyronitrile was added over 6 hours. Polymerization proceeded at 98% or more at the stage of reaction for a total of 20 hours, and a polymer fine particle aqueous dispersion (1) having a mass ratio of PEGMA / St / AN = 10/10/80 was prepared. The particle size distribution of the polymer fine particles had a maximum value at a particle size of 150 nm.

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

3. Evaluation of planographic printing plate precursor The on-press development type lithographic printing plate precursor thus obtained was evaluated for visibility, on-press developability and printing durability as follows.
(1) Visibility After storing the lithographic printing plate precursor in an oven at 60 ° C. for 2 days, using a Trendsetter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser, the output is 11.7 W, the outer drum rotation speed is 250 rpm, and the resolution is 2400 dpi Exposure was performed under conditions. Visibility was evaluated after leaving the exposed lithographic printing plate precursor as it was in a dark place at 25 ° C. and an atmosphere of 50% relative humidity for 30 minutes. Visibility was evaluated by the difference ΔL between the L value of the exposed area and the L value of the unexposed area using the L value (brightness) of the L ^* a ^* b ^* color system. It means that visibility is excellent, so that the value of (DELTA) L is large. The measurement was performed by the SCE (regular reflected light removal) method using a spectrocolorimeter CM2600d manufactured by KONICA-MINOLTA and operation software CM-S100W. In the SCE method, specularly reflected light is removed and only diffused light is measured. Therefore, the color is evaluated as close to visual observation, and correlates well with visibility by an actual person. The results are shown in Table 1.

(2) On-machine developability The lithographic printing plate precursor was exposed with a Luxel PLANETSETTER T-6000III equipped with an infrared semiconductor laser under the conditions of an outer drum rotation speed of 1000 rpm, a laser output of 70%, and a resolution of 2400 dpi. The exposure 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 the plate cylinder of a printing machine LITHRONE 26 manufactured by Komori Corporation without developing. Equality-2 (manufactured by FUJIFILM Corporation) / tap water = 2/98 (volume ratio) dampening water and Values-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.) Dampening water and ink were supplied by the standard automatic printing start method of LITHRONE 26, and 100 sheets were printed on Tokuhishi Art (76.5 kg) paper at a printing speed of 10,000 sheets per hour.
On-press development was evaluated as the on-press developability of the number of print sheets required until the on-press development of the unexposed portion of the image recording layer was completed on the printing press and no ink was transferred to the non-image portion. The results are shown in Table 1.

(3) Printing durability After the on-press developability was evaluated, printing was further continued. As the number of printed sheets was increased, the image recording layer was gradually worn out, so that the ink density on the printed material decreased. The number of copies printed when the dot area ratio of 50% halftone dots of FM screen in the printed matter was 5% lower than the measurement value of the 100th printed sheet was evaluated as printing durability. The results are shown in Table 1.

From the results in Table 1, the lithographic printing plate precursor containing the specific cyanine dye of the present invention is equivalent to the lithographic printing plate precursor of Comparative Example even when stored in an oven at 60 ° C. for 2 days (simulation of long-term storage). It is clear that extremely good visibility is exhibited as compared with the planographic printing plate precursor of the comparative example while exhibiting excellent on-press developability (for example, comparison between Example 1 and Comparative Example 1 or Comparative Example 3). ). Furthermore, it can be seen that the lithographic printing plate precursor of the present invention has significantly improved printing durability compared with the lithographic printing plate precursor of the comparative example (for example, in Example 1 and Comparative Example 1 or Comparative Example 3). Contrast).
That is, as in Comparative Example 1 or 3, carbonization (on R ⁹ to R ¹² in the general formula (1) or (2)) on the phenylene group of the radical generator skeleton bonded to the infrared absorber skeleton in the specific cyanine dye. A compound having no hydrogen group or only one compound is significantly inferior in visibility and printing durability after aging. Thus, it is surprising that excellent characteristics can be obtained by slight differences in structure, and the effect of the specific cyanine dye of the present invention is extremely specific and unexpected.
Moreover, when the infrared absorber and radical generator which comprise a specific cyanine pigment | dye are used separately like the comparative example 4, said effect is not expressed.
Furthermore, it is understood that the printing durability is further improved by using a specific cyanine dye and a borate compound in combination. From the comparison between Comparative Example 1 and Comparative Example 2, the improvement in printing durability by the combined use of the borate compound is slight, whereas the improvement in printing durability by using the specific cyanine dye and the borate compound is remarkable. This effect is very specific and unexpected.

[Examples 26 to 50 and Comparative Examples 5 to 8]
1. Production of developer-processed planographic printing plate precursors (for Examples 26 to 47 and Comparative Examples 5 to 8)

<Formation of undercoat layer>
On the said support B, the following coating liquid (2) for undercoat layers was apply | coated with the wire bar, and it dried at 90 degreeC for 30 second (s). The dry coating amount was 10 mg / m ² .

<Coating liquid for undercoat layer (2)>
-Polymer compound A (Mw: 10,000) having the following structure 0.05 g
・ Methanol 27g
・ Ion exchange water 3g

<Formation of image recording layer>
The following image recording layer coating solution (3) was prepared, applied onto the undercoat layer formed as described above using a wire bar, and dried to form an image recording layer. Drying was performed at 125 ° C. for 34 seconds using a warm air dryer. The coating amount after drying was 1.4 g / m ² .

<Coating liquid for image recording layer (3)>
-Cyanine dye represented by the general formula (1) 0.020 g
Or a compound for comparison [listed in Table 2]
・ Borate compound 0.010g
TPB [Structure] (When added)
-Pentaerythritol triacrylate hexamethylene 1.33 g
Diisocyanate urethane prepolymer (UA-306H, manufactured by Kyoeisha Chemical Co., Ltd.)
-Binder polymer (2) [the following structure] 1.35 g
・ Ethyl violet 0.04g
・ Fluorine surfactant 0.025g
(Megafuck F-780-F DIC Corporation,
Methyl isobutyl ketone (MIBK) 30% by mass solution)
・ Methyl ethyl ketone 18.4g
・ Methanol 9.83g
・ 18.4 g of 1-methoxy-2-propanol

<Formation of lower protective layer>
On the image recording layer, synthetic mica (Somasif MEB-3L, 3.2 mass% aqueous dispersion, manufactured by Co-op Chemical Co., Ltd.), polyvinyl alcohol (Goselan CKS-50, saponification degree 99 mol%, polymerization degree 300) , Sulfonic acid-modified polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), surfactant A (Emalex 710, manufactured by Nippon Emulsion Co., Ltd.) and surfactant B (Adeka Pluronic P-84, manufactured by ADEKA Corporation) ) Was applied with a wire bar and dried at 125 ° C. for 30 seconds with a hot air dryer.
The content ratio of synthetic mica (solid content) / polyvinyl alcohol / surfactant A / surfactant B in the coating solution for forming the lower protective layer is 7.5 / 89/2 / 1.5 (mass%). Yes, the coating amount after drying was 0.5 g / m ² .

<Formation of upper protective layer>
On the lower protective layer, an organic filler (Art Pearl J-7P, manufactured by Negami Industrial Co., Ltd.), synthetic mica (Somasif MEB-3L, 3.2% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.), polyvinyl alcohol (L-3266: saponification degree 87 mol%, polymerization degree 300, sulfonic acid-modified polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), thickener (Serogen FS-B, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) And a surfactant (Emalex 710, manufactured by Nippon Emulsion Co., Ltd.) mixed aqueous solution (coating solution for forming the upper protective layer) was applied with a wire bar, and dried at 125 ° C. for 30 seconds with a hot air dryer. .
The content ratio of the organic filler / synthetic mica (solid content) / polyvinyl alcohol / thickener / surfactant in the coating solution for forming the upper protective layer is 3.2 / 2.0 / 80.5 / 11.5. /2.8 (mass%), and the coating amount after drying was 1.76 g / m ² .

2. Preparation of developer-processed lithographic printing plate precursor (for Examples 48 to 50) Using the support having the undercoat layer used in the developer-processed lithographic printing plate precursor for Example 26 above, on this undercoat layer, An image recording layer coating solution (4) having the following composition was applied to a bar and oven-dried at 70 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 0.6 g / m ^2. A lithographic printing plate precursor without a protective layer was prepared.

<Image recording layer coating solution (4)>
-Cyanine dye represented by the general formula (1) [described in Table 2] 0.020 g
・ Borate compound 0.010g
TPB [said structure]
・ Polymer (A) 0.9g
・ Hybridur 580 (Air Products and Chemicals)
1.2g
・ Polymerizable monomer 1.35 g
SR-399 (Sartomer)
・ NK Ester A-DPH (Kowa American) 1.35g
・ CD9053 (Sartomer) 0.25g
・ Fluor N 2900 (Cytonix) 0.05g
・ Pigment 1 0.4g
・ 1-methoxy-2-propanol 50.0g
・ Γ-Butyrolactone 15.0g
・ Methyl ethyl ketone 60.0g
・ Water 15.0g

In the image recording layer coating solution (4), the compounds described by trade names are as follows.
Hybridur 580: polyurethane acrylic hybrid dispersion SR-399: dipentaerythritol pentaacrylate NK Ester A-DPH: dipentaerythritol hexaacrylate CD 9053: trifunctional acid ester FluorN 2900: perfluoropolyether polyethylene glycol ( 550) Block polymer pigment 1: 7.7% of the total solid content is polyvinyl acetal obtained by acetalizing polyvinyl alcohol with acetaldehyde, butyraldehyde and 4-formylbenzoic acid, 76.9% is Irgalith Blue GLVO (Cu-phthalocyanine CI Pigment Blue 15: 4), 1 mass% 1-methoxy-2-propanol dispersion of 15.4% dispersion aid (Disperbyk 167, Byk Chemie)

The synthesis method of the polymer (A) used in the image recording layer coating solution (4) is shown below.
<Synthesis of polymer (A)>
A 1000 ml three-necked flask was equipped with a stirrer, thermometer, dropping funnel, nitrogen inlet tube, reflux condenser, nitrogen gas was introduced for deoxygenation, and 2,2′-azobisisobutyronitrile ( 1.6 g), methyl methacrylate (20 g), acrylonitrile (24 g), N-vinylcarbazole (20 g), methacrylic acid (16 g), N, N′-dimethylacetamide (320 g) were added, and the temperature was 60 ° C. for about 16 hours. Heated.
When an aqueous solution of potassium hydroxide (5.2 g) (water, 40 g) was slowly added to the reaction mixture, the reaction mixture became a highly viscous liquid. After stirring for 10 minutes, allyl bromide (13.3 g) was added and heated at 55 ° C. for 3 hours. To the reaction mixture was added concentrated hydrochloric acid (12 g) diluted with N, N′-dimethylacetamide (40 g), and the mixture was further stirred for 3 hours. The reaction solution was slowly added to a mixture of ice water (12 liters) and concentrated hydrochloric acid (20 g) and stirred for a while. The resulting precipitate was filtered, washed with 2000 mL 2-propanol, and then with 2000 mL water to give a white powder. This powder was air-dried overnight and then dried at 50 ° C. for 3 hours to obtain 80 g of polymer (A).

[Plate making method]
The obtained developer-processed lithographic printing plate precursor was processed according to each step of image exposure, development processing, and drying.
Image exposure was performed with an infrared semiconductor laser (Trendsetter 3244VX manufactured by Creo, equipped with a water-cooled 40 W infrared semiconductor laser) under conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2,400 dpi. A solid image was used for printing durability evaluation.
After exposure, the lithographic printing plate precursor having a protective layer is washed with water to remove the protective layer, and then developed with a developer HN-D (former product name: DH-N) manufactured by FUJIFILM Corporation. : Development processing was carried out using a 4 water dilution. The pH of the developer was 12, and the temperature of the developer bath was 30 ° C. The developer was showered from the spray pipe with a circulation pump and supplied to the plate surface of the lithographic printing plate precursor. The tank capacity of the developer was 10 liters. After development, a water washing treatment was performed to remove the developer adhering to the plate surface. Thereafter, air-drying at 50 ° C. for 2 seconds was performed to prepare a lithographic printing plate.

3. Evaluation of planographic printing plate The obtained planographic printing plate is attached to the plate cylinder of a printing machine LITHRONE26 manufactured by Komori Corporation, and the same method as described in the on-press developability evaluation of the on-press development type lithographic printing plate precursor is performed. 100 sheets were printed, and then the printing durability was evaluated in the same manner as described in Evaluation of printing durability. The results are shown in Table 2.

From the results of Table 2, it can be seen that the lithographic printing plate precursor containing the specific cyanine dye of the present invention has significantly improved printing durability compared to the lithographic printing plate precursor of the comparative example (for example, Examples 26 and Comparative Example 5 or Comparative Example 7).
That is, as in Comparative Example 5 or 7, carbonization (on R ⁹ to R ¹² in the general formula (1) or (2)) on the phenylene group of the radical generator skeleton bonded to the infrared absorber skeleton in the specific cyanine dye. A compound having no hydrogen group or having only one group is greatly inferior in printing durability. Thus, it is surprising that excellent characteristics can be obtained by slight differences in structure, and the effect of the specific cyanine dye of the present invention is extremely specific and unexpected.
Moreover, when the infrared absorber and radical generator which comprise a specific cyanine pigment | dye are used separately like the comparative example 8, said effect is not expressed.
Furthermore, it is understood that the printing durability is further improved by using a specific cyanine dye and a borate compound in combination. From the comparison between Comparative Example 5 and Comparative Example 6, the improvement in printing durability by the combined use of the borate compound is slight, whereas the improvement in printing durability by using the specific cyanine dye and the borate compound is remarkable. This effect is very specific and unexpected.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on September 30, 2013 (Japanese Patent Application No. 2013-204393), the contents of which are incorporated herein by reference.

Claims

A lithographic printing plate precursor having an image recording layer containing (A) a cyanine dye represented by the following general formula (1), (B) a binder polymer and (C) a polymerizable monomer on a support.

In general formula (1), R 1 and R 8 each independently represent a hydrocarbon group. R 2 , R 3 , R 4 , R 5 , R 6 and R 7 each independently represent a hydrogen atom or a hydrocarbon group. R 4 and R 5 may be connected to each other to form a ring. Q 1 and Q 2 each independently represent —NR 0 —, S, O, —CH═CH—, or a dialkylmethylene group. R 0 represents a hydrogen atom or a hydrocarbon group. T 1 and T 2 each independently represents an atomic group necessary for forming an aromatic ring or a heteroaromatic ring. A − and B − each independently represent a counter ion selected from a halide ion, a perchlorate ion, a tetraphenylborate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion. R 9 to R 22 each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, provided that at least two of R 13 to R 22 are selected from a chlorine atom, a fluorine atom and a trifluoromethyl group. It is an electron withdrawing group, and at least two of R 9 to R 12 are hydrocarbon groups having 1 to 3 carbon atoms.
The lithographic printing plate precursor as claimed in claim 1, wherein the (A) cyanine dye is a cyanine dye represented by the following general formula (2).

In general formula (2), R 1 , R 2 , R 3 , R 6 , R 7 , R 8 , T 1 , T 2 , A − and B − are R 1 , R 2 in general formula (1), respectively. , R 3 , R 6 , R 7 , R 8 , T 1 , T 2 , A − and B − . R 9 to R 22 each independently represents a hydrogen atom, a halogen atom or a monovalent organic group, provided that at least two of R 13 to R 22 are electrons selected from a chlorine atom, a fluorine atom and a trifluoromethyl group. It is an attractive group, and at least two of R 9 to R 12 are hydrocarbon groups having 1 to 3 carbon atoms.
The lithographic printing plate precursor as claimed in claim 2, wherein in the cyanine dye represented by the general formula (2), at least two of R 13 to R 22 are chlorine atoms.
The lithographic printing plate precursor as claimed in claim 2 or 3, wherein in the cyanine dye represented by the general formula (2), R 9 and R 11 are each a hydrocarbon group having 1 to 3 carbon atoms.
The lithographic printing plate precursor as claimed in any one of claims 1 to 4, wherein the image recording layer further comprises a borate compound.
The lithographic printing plate precursor as claimed in claim 5, wherein the borate compound is a tetraphenylborate salt.
The lithographic printing plate precursor as claimed in any one of Claims 1 to 6, wherein the image recording layer further comprises fine polymer particles.
The lithographic printing plate precursor as claimed in any one of claims 1 to 7, further comprising a protective layer on the image recording layer.
The lithographic printing plate precursor as claimed in claim 8, wherein the protective layer contains an inorganic stratiform compound.
The lithographic printing plate precursor as claimed in any one of claims 1 to 9, wherein the (B) binder polymer has an alkylene oxide group.
The lithographic printing plate precursor as claimed in any one of claims 1 to 10, wherein an unexposed portion of the image recording layer can be removed by at least one of dampening water and printing ink.
The lithographic printing plate precursor according to claim 11, wherein the lithographic printing plate precursor is image-exposed with an infrared laser, and then an unexposed portion of the image recording layer is removed on a printing machine by at least one of dampening water and printing ink. Method.