JP5172121B2 - Planographic printing plate precursor and planographic printing method - Google Patents

Description

  The present invention relates to a so-called direct plate-making lithographic printing plate precursor that can be directly made by scanning laser light based on a digital signal from a computer or the like, and a lithographic printing method using the lithographic printing plate precursor. .

  Conventionally, negative lithographic printing plate precursors (negative PS plates) are widely known and have various photosensitive layers (image recording layers). There are diazo resin-containing type, photopolymerization type, photocrosslinking type and the like. In order to produce such a lithographic printing plate, it is common to place a transparent negative film manuscript (lith film) on these lithographic printing plates and to expose the image using ultraviolet rays. It took time and effort. In recent years, with the development of image forming technology, computer-to-plate technology has been developed, in which plate exposure is performed directly on a lithographic printing plate precursor without using a lithographic film by laser exposure based on digital data such as a computer. Sensitive laser recording lithographic printing plate precursors have been developed.

  As the photosensitive layer used in these laser recording type lithographic printing plate precursors, a photopolymerization system is most suitable in terms of high sensitivity. However, since the polymerization-based photosensitive layer (photopolymerization layer) does not necessarily have a strong adhesive force with the support, when used for printing a large number of copies at a high speed, solid images may be lost, fine lines and highlight portions may be thinned, It causes a problem of flying. Therefore, in high-sensitivity photopolymerization systems, photoadhesiveness between the support and the photosensitive layer is an important factor, and many researches and developments have been made.

  For example, it is known that a polymer having a polymerizable group having an ethylenically unsaturated bond and a phosphate group is provided between a polymerization type photosensitive layer and a support (see Patent Document 1). In addition, a technique is also known in which a functional group capable of causing an addition reaction due to a radical is provided on the support surface by a covalent bond so as to have an adhesive force with the photopolymerization type photosensitive layer (for example, Patent Documents 2 to 2). 4). A photosensitive layer and a support comprising a compound obtained by hydrolyzing and dehydrating and condensing a silane coupling agent having an ethylenic double bond, and a compound containing an alkylene oxide chain and an acryloyl group or methacryloyl group in one molecule. It is also known to provide between (see Patent Document 5).

In addition, a technique for improving adhesion to a support by incorporating a phosphate ester compound having a (meth) acryloyl group into a photosensitive layer is also known (see Patent Document 6).
JP-A-2-304441 Japanese Patent Laid-Open No. 3-56177 Japanese Patent Laid-Open No. 7-159838 JP-A-8-320551 Japanese Patent Laid-Open No. 10-282679 Japanese Patent Laid-Open No. 11-30858

However, from the practical viewpoint, these conventional technologies are still insufficient in any of fine line reproducibility, printing durability, stain resistance, and on-press developability, and further improvements have been desired.
The object of the present invention is to provide a lithographic printing plate precursor and a lithographic printing method which can be developed on-machine after image exposure with a laser and have good fine line reproducibility, printing durability and stain resistance. It is to be.

[1]
A lithographic printing plate precursor having an undercoat layer and a laser-sensitive photopolymerization layer on a hydrophilic support, wherein the undercoat layer comprises at least (a1) a repeating unit selected from the following formula and (a2) a support surface A lithographic printing plate precursor comprising a copolymer having a repeating unit having at least one functional group that interacts with the substrate.



[2]
The lithographic printing plate precursor as described in [1], wherein the copolymer has a mass average molecular weight of at least 20,000.
[3]
The lithographic printing plate precursor as described in [1] or [2], wherein the photopolymerizable layer contains an infrared absorber.
[4]
The lithographic printing plate precursor as described in any one of [1] to [3], wherein the copolymer further comprises (a3) a repeating unit having at least one hydrophilic group.
[5]
The lithographic printing plate precursor as described in [4], wherein the repeating unit (a3) having at least one hydrophilic group is a repeating unit represented by the following general formula (A3).

(In General Formula (A3), R _{1 to} R ₃ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. A represents an oxygen atom or NR ⁷ —, and R ⁷ represents hydrogen. An atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, L ₁ represents a linear linking group having 5 to 20 atoms constituting the main skeleton of the linking group, and W is the following general formula. Represents a hydrophilic group selected from the group represented.)

In the above formula, M ₁ represents a hydrogen atom, a metal atom, or an ammonium group, and R ₇ and R ₈ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.
[6]
The lithographic printing plate precursor as described in any one of [1] to [5], wherein the photopolymerizable layer contains microcapsules or microgels.
[7]
A lithographic printing plate precursor having an undercoat layer and a laser-sensitive photopolymerization layer on a hydrophilic support, the undercoat layer comprising at least (a1) a repeating unit having at least one ethylenically unsaturated bond; (A2) contains a copolymer having a repeating unit having at least one functional group that interacts with the support surface and (a3) a repeating unit having at least one hydrophilic group, and the repeating unit of (a3) is: A lithographic printing plate precursor comprising a repeating unit represented by the general formula (A3).

(In General Formula (A3), R _{1 to} R ₃ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. A represents an oxygen atom or NR ⁷ —, and R ⁷ represents hydrogen. An atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, L ₁ represents a linear linking group having 5 to 20 atoms constituting the main skeleton of the linking group, and W is the following general formula. Represents a hydrophilic group selected from the group represented.)

In the above formula, M ₁ represents a hydrogen atom, a metal atom, or an ammonium group, and R ₇ and R ₈ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.
[8]
The lithographic printing plate precursor according to any one of [1] to [7] is mounted on a printing press and imagewise laser-exposed or imagewise exposure with a laser and then mounted on a printing press. And a lithographic printing method in which printing ink and fountain solution are supplied to the lithographic printing plate precursor to remove a laser unexposed portion of the photopolymerization layer and print.
Although this invention is invention which concerns on said [1]-[8], hereafter, it describes also about other matters (for example, the following 1-7).
1. A lithographic printing plate precursor having an undercoat layer and a laser-sensitive photopolymerization layer on a hydrophilic support, the undercoat layer comprising at least (a1) a repeating unit having at least one ethylenically unsaturated bond; (A2) a copolymer having a repeating unit having at least one functional group that interacts with the support surface, wherein the repeating unit of (a1) is represented by the following general formula (A1): A lithographic printing plate precursor.

(In General Formula (A1), R _{1 to} R ₃ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. R _{4 to} R ₆ each independently represent a hydrogen atom or carbon. Represents an alkyl group, a halogen atom, an acyl group, or an acyloxy group of formulas 1 to _6. R ₄ and R ₅ or R ₅ and R ₆ may form a ring, A represents an oxygen atom or NR ⁷ , R ⁷ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and L ₁ represents a linear linking group.)

  2. 2. The lithographic printing plate precursor as described in 1 above, wherein the copolymer further comprises (a3) a repeating unit having at least one hydrophilic group.

  3. A lithographic printing plate precursor having an undercoat layer and a laser-sensitive photopolymerization layer on a hydrophilic support, the undercoat layer comprising at least (a1) a repeating unit having at least one ethylenically unsaturated bond; (A2) contains a copolymer having a repeating unit having at least one functional group that interacts with the support surface and (a3) a repeating unit having at least one hydrophilic group, and the repeating unit of (a3) is: A lithographic printing plate precursor comprising a repeating unit represented by the general formula (A3).

(In General Formula (A3), R _{1 to} R ₃ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. A represents an oxygen atom or NR ⁷ —, and R ⁷ represents hydrogen. Represents an atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, L ₁ represents a linear linking group, and W represents a hydrophilic group.)

4). 4. The lithographic printing plate precursor as described in any one of 1 to 3 above, wherein the copolymer has a mass average molecular weight of at least 20,000.
5. 5. The lithographic printing plate precursor as described in any one of 1 to 4 above, wherein the photopolymerization layer contains an infrared absorber.
6). The lithographic printing plate precursor as described in any one of 1 to 5 above, wherein the photopolymerizable layer contains microcapsules or microgels.
7). The lithographic printing plate precursor according to any one of 1 to 6 above is mounted on a printing press and imagewise laser exposed, or after imagewise exposure with a laser and then mounted on a printing press, A lithographic printing method in which printing ink and fountain solution are supplied to a lithographic printing plate precursor to remove the laser unexposed portion of the photopolymerization layer and print.

In the present invention, the above-mentioned problem can be solved by including the above-mentioned copolymer in an undercoat layer between a laser-sensitive photopolymerization layer and a support. The mechanism of action is not necessarily clear, but is presumed as follows.
When the copolymer in the undercoat layer has an ethylenically unsaturated group, the radical addition reaction by exposure proceeds in the photopolymerization layer, and at the same time, the addition reaction occurs in the undercoat layer and at the interface between the photopolymerization layer and the undercoat layer. As the process proceeds, the adhesion between both layers is strengthened.
Further, when the copolymer has a functional group that interacts with the surface of the support, a non-image portion in which the undercoat layer is exposed is formed after on-press development. When the copolymer has a hydrophilic group, the hydrophilic group is oriented on the surface, it becomes difficult for ink to adhere to the non-image area, and stain resistance is improved.
In the copolymer of the present invention, at least one of an ethylenically unsaturated group or a hydrophilic group is separated from the polymer main chain by a linking group and has a structure that can move easily. Such ethylenically unsaturated groups have improved reactivity, and the adhesive strength between the undercoat layer and the photopolymerization layer is enhanced even with a small exposure amount, and the image strength is improved. As a result, higher sensitivity and higher resistance are obtained. Printability is achieved. On the other hand, mobile hydrophilic groups respond more quickly to dampening water and are more easily oriented on the surface, further enhancing the antifouling effect.

  According to the present invention, it is possible to provide a lithographic printing plate precursor and a lithographic printing method which can be developed on-machine after image exposure with a laser and have good fine line reproducibility, printing durability and resistance to stains.

(Undercoat layer)
One of the embodiments of the undercoat layer in the present invention (embodiment 1 of the present invention) includes at least (a1) a repeating unit having at least one ethylenically unsaturated bond and (a2) a functional group that interacts with the support surface. The repeating unit of (a1) contains a copolymer represented by the following general formula (A1). In another embodiment of the undercoat layer of the present invention (embodiment 2 of the present invention), at least (a1) a repeating unit having at least one ethylenically unsaturated bond and (a2) a functional group that interacts with the support surface are provided. It has at least one repeating unit and (a3) a repeating unit having at least one hydrophilic group, and the repeating unit of (a3) contains a copolymer represented by the following general formula (A3) To do. In Embodiment 1 of the present invention, it is preferable that the copolymer further has (a3) a repeating unit having at least one hydrophilic group.
Hereinafter, the copolymer of the present invention is referred to as a specific copolymer.

(In General Formula (A1), R _{1 to} R ₃ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. R _{4 to} R ₆ each independently represent a hydrogen atom or carbon. Represents an alkyl group, a halogen atom, an acyl group, or an acyloxy group of formulas 1 to _6. R ₄ and R ₅ or R ₅ and R ₆ may form a ring, A represents an oxygen atom or NR ⁷ , R ⁷ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and L ₁ represents a linear linking group.)

(In General Formula (A3), R _{1 to} R ₃ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. A represents an oxygen atom or NR ⁷ —, and R ⁷ represents hydrogen. Represents an atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, L ₁ represents a linear linking group, and W represents a hydrophilic group.)

<Specific copolymer>
As the specific copolymer, a copolymer represented by the following formula (I) is preferable.

In formula (I), A ₁ is a repeating unit containing at least one ethylenically unsaturated bond, A ₂ is a repeating unit containing at least one functional group that interacts with the support surface, and A ₃ Is a repeating unit having at least one hydrophilic group. x, y, z represents a copolymerization ratio.

If aspect 1 of the present invention, the repeating unit represented by A ₁ in formula (I) is represented by the above formula (A1).
In the above formula (A1), L ₁ represents a linear linking group, and specifically includes two or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, an oxygen atom, a nitrogen atom and a sulfur atom. Represents a linking group that is constructed. The number of atoms constituting the main skeleton of the linking group represented by L ₁ is preferably 1 to 70, more preferably 1 to 60, and still more preferably 1 to 50.
The main skeleton of the linking group in the present invention refers to an atom or an atomic group used only for linking A in the general formula (A1) and the terminal ethylenically unsaturated bond. Below to exemplify the structure of the compound represented by the general formula (A1) of the present invention, showing the number of atoms and their calculation method constituting the main skeleton of the linking group represented by L ₁ in its structure.

In the formula (I), the repeating unit represented by A ₂ is preferably a repeating unit represented by the following formula (A2).

In formula, R < ₁ > -R < ₃ > is synonymous with what is represented by the said formula (A1). L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Q represents a functional group that interacts with the support surface (hereinafter sometimes abbreviated as “specific functional group”).

Specific examples of L composed of combinations are given below. In the following examples, the left side is bonded to the main chain, and the right side is bonded to the specific functional group Q.
L1: -CO-NH-divalent aliphatic group -O-CO-
L2: —CO—divalent aliphatic group —O—CO—
L3: -CO-O-divalent aliphatic group -O-CO-
L4: -Divalent aliphatic group -O-CO-
L5: -CO-NH-divalent aromatic group -O-CO-
L6: -CO-divalent aromatic group -O-CO-
L7: -Divalent aromatic group -O-CO-
L8: -CO-divalent aliphatic group-CO-O-divalent aliphatic group-O-CO-
L9: -CO-divalent aliphatic group-O-CO-divalent aliphatic group-O-CO-
L10: -CO-Divalent aromatic group -CO-O-Divalent aliphatic group -O-CO-
L11: -CO-Divalent aromatic group -O-CO-Divalent aliphatic group -O-CO-
L12: -CO-divalent aliphatic group-CO-O-divalent aromatic group-O-CO-
L13: -CO-Divalent aliphatic group -O-CO-Divalent aromatic group -O-CO-
L14: -CO-divalent aromatic group-CO-O-divalent aromatic group-O-CO-
L15: -CO-Divalent aromatic group -O-CO-Divalent aromatic group -O-CO-
L16: -CO-O-divalent aromatic group -O-CO-NH-divalent aliphatic group -O-CO-
L17: -CO-O-divalent aliphatic group -O-CO-NH-divalent aliphatic group -O-CO-
L18: —CO—NH—
L19: -CO-O-

The divalent aliphatic group means an alkylene group, a substituted alkylene group, an alkenylene group, a substituted alkenylene group, an alkynylene group, a substituted alkynylene group or a polyalkyleneoxy group. Of these, an alkylene group, a substituted alkylene group, an alkenylene group, and a substituted alkenylene group are preferable, and an alkylene group and a substituted alkylene group are more preferable.
The divalent aliphatic group is preferably a chain structure rather than a cyclic structure, and more preferably a linear structure than a branched chain structure. The number of carbon atoms in the divalent aliphatic group is preferably 1 to 20, more preferably 1 to 15, further preferably 1 to 12, and further preferably 1 to 10. It is preferably 1 to 8, and most preferably.

  Examples of the substituent of the divalent aliphatic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, an amino group, a cyano group, an aryl group, an alkoxy group, an aryloxy group, and an acyl group. , Alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, monoalkylamino group, dialkylamino group, arylamino group and diarylamino group.

The divalent aromatic group means an arylene group or a substituted arylene group. Preferable are phenylene, substituted phenylene group, naphthylene and substituted naphthylene group.
Examples of the substituent for the divalent aromatic group include an alkyl group in addition to the examples of the substituent for the divalent aliphatic group.

  Among L1 to L19, L1, L3, L5, L7, and L17 are preferable.

Examples of the specific functional group Q include a covalent bond, an ionic bond, a hydrogen bond, a polar interaction, a van der Waals with a metal, a metal oxide, a hydroxyl group and the like present on a support subjected to an anodizing treatment or a hydrophilic treatment. Examples include groups capable of interaction such as interaction.
Specific examples of the specific functional group are listed below.

(In the above formula, R _{11 to} R ₁₃ each independently represents a hydrogen atom, an alkyl group, an aryl group, an alkynyl group, or an alkenyl group, and M ₁ and M ₂ each independently represent a hydrogen atom, a metal atom, or Represents an ammonium group, and X ⁻ represents a counter anion.)
Among these, the specific functional group is preferably an onium base such as an ammonium group or a pyridinium group, or a β-diketone group such as a phosphate group, a phosphonic acid group, a boric acid group, or an acetylacetone group.

In aspect 1 of the present invention, the repeating unit represented by A ₃ in formula (I) is preferably represented by the following formula (A3 ′).

In formula, R < ₁ > -R < ₃ > is synonymous with what is represented by the said formula (A1). L is synonymous with that represented by the formula (A2). W represents a hydrophilic group. The hydrophilic group is preferably a group selected from the following groups.

However, M < ₁ > represents a hydrogen atom, a metal atom, or an ammonium group, R < ₇ > and R < ₈ > represents a hydrogen atom or a C1-C6 linear or branched alkyl group each independently. R ₉ represents a linear or branched alkylene group having 1 to 6 carbon atoms, preferably an ethylene group. R ₁₀ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. n represents an integer of 1 to 100, and preferably 1 to 30.

  As said W, what contains a carboxylic acid (salt) group and a sulfonic acid (salt) group is more preferable, and especially what contains a sulfonic acid (salt) group is preferable from a viewpoint of stain | pollution | contamination prevention property.

In the aspect 2 of the present invention, the repeating unit represented by A ₁ in the formula (I) is preferably represented by the following formula (A1 ′).

In formula (A1 ′), R _{1 to} R ₆ have the same meanings as those represented by formula (A1). L represents a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Specific examples of L composed of combinations include L1 to L19 of the specific examples of L in the formula (A2). Among L1 to L19, L1, L3, L5, L7, and L17 are preferable.

In Embodiment 2 of the present invention, the repeating unit represented by A ₁ of formula (I) may be a repeating unit represented by formula (A1) above.

In the case of the embodiment 2 of the present invention, the repeating unit represented by A ₃ in the formula (I) is represented by the formula (A3).
In formula (A3), L1 represents a linear linking group, and specifically includes two or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, an oxygen atom, a nitrogen atom, and a sulfur atom. Represents a linking group. The number of atoms constituting the main skeleton of the linking group represented by L1 is preferably 4 or more, more preferably 5 to 20, and still more preferably 5 to 15.
The main skeleton of the linking group in the present invention refers to an atom or an atomic group used only for linking A and W in the general formula (A3). Below, the structure of the compound represented by general formula (A3) of this invention is illustrated, and it shows about the number of atoms which comprise the main skeleton of the coupling group represented by L1 in the structure, and its calculation method.

  In the formula (A3), the hydrophilic group W is preferably a group selected from the following groups.

In the above formula, M ₁ represents a hydrogen atom, a metal atom, or an ammonium group, and R ₇ and R ₈ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.

  As W, those containing a carboxylic acid (salt) group and a sulfonic acid (salt) group are preferred, and those containing a sulfonic acid (salt) group are particularly preferred from the viewpoint of stain resistance.

The specific copolymer of the present invention includes other monomers (1) to (11) described below as long as the effects of the present invention are not impaired other than the repeating units represented by A ₁ , A ₂ and A _3. It may be a copolymer with one or more selected from the group consisting of

(Other monomers)
(1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(2) Methyl acrylate, ethyl acrylate, propyl acrylate, amyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoalkylate Acrylates and the like.
(3) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate, polyethylene glycol monomethacrylate, polypropylene Methacrylates such as glycol monomethacrylate.

(4) Acrylamide, methacrylamide, N-methylolacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.
(5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and phenyl vinyl ether.
(6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.

(7) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene.
(8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(9) Olefins such as ethylene, propylene, isobutylene, butadiene, and isoprene.
(10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
(11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

The molecular weight of the specific copolymer is preferably 20,000 or more in terms of mass average molecular weight from the viewpoint of stain resistance and printing durability. Further, (A ₁ ) is preferably from 1 to 80 mol%, more preferably from 2 to 50 mol%, based on all copolymerized monomers. (A ₂₎ is 1 to 80 mol% are preferred with respect to the total copolymerizable monomer, more preferably 2 to 40 mol%. (A ₃ ) is preferably from 10 to 95 mol%, more preferably from 20 to 90 mol%, based on all copolymerized monomers.

  Specific examples of the specific copolymer used in the present invention are shown below, but the present invention is not limited thereto.

<Formation of undercoat layer>
Formation of the undercoat layer using the specific copolymer is usually carried out by dissolving the specific copolymer in a solvent to prepare a coating solution and coating the support. Examples of the solvent include water and organic solvents such as methanol, ethanol, propanol, isopropanol, ethylene glycol, hexylene glycol, tetrahydrofuran, dimethylformamide, 1-methoxy-2-propanol, dimethylacetamide, and dimethyl sulfoxide. Are preferred. These organic solvents can also be mixed and used.

  As a density | concentration of undercoat layer coating liquid, 0.001-10 mass% is preferable, More preferably, it is 0.01-5 mass%, More preferably, it is 0.05-1 mass%. If necessary, a surfactant (described later in the section of the photopolymerization layer) may be added to the undercoat layer. Various known methods can be used as a method of applying the undercoat layer coating solution to the support. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

The coating amount (solid content) of the undercoat layer is preferably from 0.1 to 200 mg / m ^2, and more preferably 1 to 50 mg / m ^2.

(Photopolymerization layer)
The lithographic printing plate precursor according to the invention is premised on having a photopolymerization layer sensitive to laser light on a hydrophilic support. Hereinafter, the components of the photopolymerization layer will be described.

<(A) Infrared absorber>
When forming an image of the lithographic printing plate precursor according to the present invention with a laser that emits infrared rays of 760 to 1200 nm using a light source, it is usually essential to use an infrared absorber. The infrared absorber has a function of converting the absorbed infrared ray into heat and a function of being excited by the infrared ray and transferring electrons / energy to a polymerization initiator (radical generator) described later. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.
Examples of preferable dyes include cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, and the like, JP-A-58-173696, Methine dyes described in JP-A-58-181690, JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, JP-A Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, and the like, and squarylium dyes described in JP-A-58-112792, etc. And cyanine dyes described in British Patent No. 434,875.

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

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

In formula (i), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. X _a ^- is Z _a which will be described below ^- has the same definition as, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom.

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

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z _a ^- represents a counter anion. However, when the cyanine dye represented by formula (i) has an anionic substituent in the structure thereof, Z _a is does not require charge neutralization ^- is not necessary. Preferred Z _a ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of storage stability of the recording layer coating solution. Hexafluorophosphate ion and aryl sulfonate ion.

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

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

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

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

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

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

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

  The addition amount of the infrared absorber is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 1 to 20% by mass with respect to the total solid content of the photopolymerization layer.

<(B) Polymerization initiator>
As a polymerization initiator used in the photopolymerization layer of the present invention, various photopolymerization initiators known in patents, literatures, etc., or a combination system of two or more photopolymerization initiators depending on the wavelength of the light source used ( Photopolymerization initiation system) can be appropriately selected and used.

  In the case of using a blue semiconductor laser, Ar laser, second harmonic of an infrared semiconductor laser, or SHG-YAG laser as a light source, various photopolymerization initiators (systems) have been proposed. 850,445, certain photoreducible dyes such as rose bengal, eosin, erythrosine, etc., or combinations of dyes and initiators, such as complex initiator systems of dyes and amines. -20099), a combination system of hexaarylbiimidazole, a radical generator and a dye (Japanese Patent Publication No. 45-37377), a system of hexaarylbiimidazole and p-dialkylaminobenzylidene ketone (Japanese Patent Publication No. 47-2528). JP, 54-155292, cyclic cis-α-dicarbonyl compound and dye system (JP 48-8) 183), a system of cyclic triazine and merocyanine dye (Japanese Patent Laid-Open No. 54-151024), a system of 3-ketocoumarin and an activator (Japanese Patent Laid-Open No. 52-112682, Japanese Patent Laid-Open No. 58-15503) , Biimidazole, styrene derivative, thiol system (JP 59-140203 A), organic peroxide and dye system (JP 59-1504 A, JP 59-140203 JP, JP JP-A 59-189340, JP-A 62-174203, JP-B 62-1641, US Pat. No. 4,766,055), a system of dye and active halogen compound (JP-A 63-1718105, JP-A-63-258903, JP-A-3-264771, etc.), a system of a dye and a borate compound (JP-A-62-143044, Japanese Unexamined Patent Publication Nos. 62-150242, 64-13140, 64-13141, 64-13142, 64-13143, 64-13144 JP-A-64-17048, JP-A-1-229003, JP-A-1-298348, JP-A-1-138204, etc.), a system comprising a dye having a rhodanine ring and a radical generator ( JP-A-2-17943, JP-A-2-244050), titanocene and 3-ketocoumarin dye system (JP-A 63-221110), titanocene and xanthene dye, addition polymerization containing amino group or urethane group A combination of possible ethylenically unsaturated compounds (JP-A-4-221958, JP-A-4-219756), Tanosen and system specific merocyanine dye (JP-A-6-295061), a dye system with titanocene and benzopyran ring (JP-A-8-334897 JP), and the like.

  In the photopolymerization layer of the lithographic printing plate precursor according to the invention, a particularly preferred photopolymerization initiator (system) contains at least one titanocene. The titanocene compound used as a photopolymerizable initiator (system) in the present invention may be any titanocene compound that can generate an active radical when irradiated with light in the presence of a sensitizing dye described later. For example, JP 59-152396 A, JP 61-151197 A, JP 63-41483 A, JP 63-41484 A, JP 2-249 A, and JP 2 -291, JP-A-3-27393, JP-A-3-12403, and JP-A-6-41170 can be appropriately selected and used.

  More specifically, di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,3,4,5 , 6-pentafluorophen-1-yl (hereinafter also referred to as “T-1”), di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di- -Cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-cyclo Pentadienyl-Ti-bis-2,4-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl Di-methylcyclopentadi Nyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, bis (cyclo And pentadienyl) -bis (2,6-difluoro-3- (pyr-1-yl) phenyl) titanium (hereinafter also referred to as “T-2”).

  These titanocene compounds can be further subjected to various chemical modifications for improving the properties of the photopolymerization layer. For example, bonding with sensitizing dyes, addition polymerizable unsaturated compounds and other radical generating parts, introduction of hydrophilic sites, compatibility improvement, introduction of substituents to suppress crystal precipitation, introduction of substituents to improve adhesion A method such as polymerization can be used.

  The use method of these titanocene compounds can be arbitrarily set as appropriate according to the performance design of the lithographic printing plate precursor as in the above-described addition polymerizable compound. For example, the compatibility with a photopolymerization layer can be improved by using 2 or more types together. A larger amount of the photopolymerization initiator such as the titanocene compound is usually advantageous in terms of photosensitivity, and is 0.5 to 80 parts by mass, preferably 1 with respect to 100 parts by mass of the nonvolatile component of the photopolymerization layer. Sufficient photosensitivity is obtained by using in the range of -50 mass parts. On the other hand, when used under a white light such as yellow, it is preferable that the amount of titanocene used is small from the viewpoint of fogging by light near 500 nm, but the amount of titanocene used in combination with a sensitizing dye is photopolymerization. Sufficient photosensitivity can be obtained even when the amount is reduced to 6 parts by mass or less, further 1.9 parts by mass or less, and further 1.4 parts by mass or less with respect to 100 parts by mass of the nonvolatile component of the layer.

As the polymerization initiator used in the present invention for initiating and advancing the curing reaction of the addition polymerizable compound, a thermal decomposition type radical generator that decomposes by heat to generate radicals is useful. Such a radical generator is used in combination with the above-described infrared absorber, and when the infrared laser is irradiated, the infrared absorber generates heat and generates radicals by the heat. Recording is possible by combining these. It becomes.
Examples of the radical generator include onium salts, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, quinonediazides, oxime ester compounds, triaryl monoalkylborate compounds, etc. Or an oxime ester compound has high sensitivity and is preferable. Below, the onium salt which can be used suitably as a polymerization initiator in this invention is demonstrated. Preferred onium salts include iodonium salts, diazonium salts, and sulfonium salts. In the present invention, these onium salts function not as acid generators but as radical polymerization initiators. The onium salt suitably used in the present invention is an onium salt represented by the following general formula (A · BR> J to (C).

In general formula (A), Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a group having 12 or less carbon atoms. An aryloxy group is mentioned. Z ^11- is from anions from halogen ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, carboxylate ions, sulfonate ions, and compounds containing —SO ₂ NHCO— or —SO ₂ NHSO ₂ —. Represents a counter ion selected from the group consisting of perchlorate ion, hexafluorophosphate ion, carboxylate ion, and aryl sulfonate ion.

In the general formula (B), Ar ²¹ represents an aryl group having 20 or less carbon atoms which may have a substituent. Preferred examples of the substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, an aryloxy group having 12 or less carbon atoms, and 12 or less carbon atoms. Examples thereof include an alkylamino group, a dialkylamino group having 12 or less carbon atoms, an arylamino group having 12 or less carbon atoms, or a diarylamino group having 12 or less carbon atoms. Z ^21- represents a counter ion having the same ^meaning as Z ^11- .

In the general formula (C), R ³¹ , R ³² and R ³³ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. Z ^31- represents a counter ion having the same ^meaning as Z ^11- .

  Specific examples of onium salts that can be suitably used as a polymerization initiator (radical generator) in the present invention include JP-A Nos. 2001-133969, 2001-343742, 2002-006482, and JP-A-2002-006482. The thing etc. which were described in each gazette of 2002-148790 can be mentioned. In the present invention, onium salts represented by general formula (A) ([OI-1] to [OI-10]) and onium salts represented by general formula (B) ([ON] which can be suitably used in the present invention are shown below. -1] to [ON-5]), and specific examples of the onium salts ([OS-1] to [OS-11]) represented by the general formula (C), are not limited thereto. .

  Specific examples of triazine compounds having a trihalomethyl group include 2,4,6-tris (monochloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2 , 4,6-tris (trichloromethyl) -s-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s -Triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (P-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-trifluoromethylphenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- [4- (4-hydroxybenzoylamino) phenyl] -4,6-bis (trichloromethyl) -s-triazine, 2- [4- (N, N-diphenylamino) phenyl]- 4,6-bis (trichloromethyl) -s-triazine, 2- (3,4-epoxyphenyl) -4, 6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6 -Bis (trichloromethyl) -s-triazine, 2- [1- (p-methoxyphenyl) -2,4-butadienyl] -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4, 6-bis (trichloromethyl) -s-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (pi-propyl-propylene) Cistyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxynaphthyl) -4, 6-bis (trichloromethyl) -s-triazine, 2-phenylthio-4,6-bis (trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2, 4,6-tris (dibromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, Examples include 2-methoxy-4,6-bis (tribromomethyl) -s-triazine.

  Examples of the triaryl monoalkyl borate compound include tetra-n-butylammonium-triphenyl-n-butyl borate.

  Moreover, the oxime ester compound which can be used suitably as a polymerization initiator in this invention is demonstrated below. Preferred oxime ester compounds include compounds represented by the following general formula (D).

  In general formula (D), X represents a carbonyl group, a sulfone group, or a sulfoxide group, and Y represents a cyclic or chain alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, or an aryl group having 6 to 18 carbon atoms. An aryl group is an aromatic hydrocarbon compound such as a benzene ring, naphthalene ring, anthracene ring, phenanthrene group, pyrene group, triphenylene group, and a heterocyclic ring is a nitrogen atom, sulfur atom, oxygen atom For example, a pyrrole group, a furan group, a thiophene group, a selenophenone group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, a thiazole group, an indole group, Benzofuran group, benzimidazole group, benzoxazole group, benzothiazole group, pyridine group Pyrimidine group, a pyrazine group, a triazine group, a quinoline group, a carbazole group, an acridine group, a phenoxazine, and a compound such as phenothiazine. These substituents represented by Y are halogen atom, hydroxyl group, nitrile group, nitro group, carboxyl group, aldehyde group, alkyl group, thiol group, aryl group or alkenyl group, alkynyl group, ether group, ester group, urea Group, amino group, amide group, sulfide group, disulfide group, sulfoxide group, sulfo group, sulfone group, hydrazine group, carbonyl group, imino group, halogen atom, hydroxyl group, nitrile group, nitro group, carboxyl group, carbonyl group, urethane It can be substituted by a compound containing a group, an alkyl group, a thiol group, an aryl group, a phosphoroso group, a phospho group, or a carbonyl ether group.

  Z in the general formula (D) is synonymous with Y or is a nitrile group, a halogen atom, a hydrogen atom, or an amino group, and these Z compounds are halogen atoms, hydroxyl groups, nitrile groups, nitro groups, carboxyl groups, aldehyde groups. , Alkyl group, thiol group, aryl group or alkenyl group, alkynyl group, ether group, ester group, urea group, amino group, amide group, sulfide group, disulfide group, sulfoxide group, sulfo group, sulfone group, hydrazine group, carbonyl Substitutable with compounds containing groups, imino groups, halogen atoms, hydroxyl groups, nitrile groups, nitro groups, carboxyl groups, carbonyl groups, urethane groups, alkyl groups, thiol groups, aryl groups, phosphoroso groups, phospho groups, carbonyl ether groups It is.

  W in the general formula (D) represents a divalent organic group, and represents a methylene group, a carbonyl group, a sulfoxide group, a sulfone group, or an imino group. The methylene group and the imino group are an alkyl group, an aryl group, an ester group, and a nitrile. It can be substituted by a compound containing a group, a carbonyl ether group, a sulfo group, a sulfo ether group, an ether group or the like. n represents an integer of 0 or 1.

V in the general formula (D) is a cyclic or chain alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, an aryl group having 6 to 18 carbon atoms, an alkoxy group, or an aryloxy group. Aromatic hydrocarbon compounds such as benzene ring, naphthalene ring, anthracene ring, phenanthrene group, pyrene group, triphenylene group, pyrrole group, furan group, thiophene group, selenophene group, pyrazole group, imidazole group, triazole group, tetrazole group, oxazole Group, thiazole group, indole group, benzofuran group, benzimidazole group, benzoxazole group, benzothiazole group, pyridine group, pyrimidine group, pyrazine group, triazine group, quinoline group, carbazole group, acridine group, phenoxazine, phenothiazine, etc. Including heteroatoms Aromatics. These V compounds are halogen atoms, hydroxyl groups, nitrile groups, nitro groups, carboxyl groups, aldehyde groups, alkyl groups, thiol groups, aryl groups or alkenyl groups, alkynyl groups, ether groups, ester groups, urea groups, amino groups, amides. Group, sulfide group, disulfide group, sulfoxide group, sulfo group, sulfone group, hydrazine group, carbonyl group, imino group, halogen atom, hydroxyl group, nitrile group, nitro group, carboxyl group, carbonyl group, urethane group, alkyl group, thiol It can be substituted by a compound containing a group, an aryl group, a phosphoroso group, a phospho group or a carbonyl ether group.
V and Z may be bonded to each other to form a ring.

As the oxime ester compound represented by the general formula (D), from the viewpoint of sensitivity, X is carbonyl, Y is an aryl group or benzoyl group, Z group is an alkyl group or aryl group, W is a carbonyl group, V Is preferably an aryl group. More preferably, the aryl group of V has a thioether substituent.
Note that the structure of the N—O bond in the general formula (D) may be E-form or Z-form.

  Other oxime ester compounds that can be suitably used in the present invention include Progress in Organic Coatings, 13 (1985) 123-150; C. S Perkin II (1979) 1653-1660; Journal of Photopolymer Science and Technology (1995) 205-232; C. S Perkin II (1979) 156-162; JP-A 2000-66385; JP-A 2000-80068.

  Although the specific example of the oxime ester compound which can be used suitably for this invention is shown below, it is not limited to this.

  The polymerization initiator used in the present invention preferably has a maximum absorption wavelength of 400 nm or less, and more preferably 360 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the lithographic printing plate precursor can be handled under white light.

  These polymerization initiators are preferably 0.1 to 50% by mass, more preferably 0.5%, based on the total solid content constituting the photopolymerization layer, from the viewpoint of sensitivity and non-image area stains that occur during printing. It can be added at a ratio of ˜30 mass%, particularly preferably 1 to 20 mass%. These polymerization initiators may be used alone or in combination of two or more. Moreover, these polymerization initiators may be added to the same layer as other components, or another layer may be provided and added thereto.

<Sensitizing dye>
In the lithographic printing plate precursor according to the invention, the photopolymerization layer may contain a sensitizing dye. The sensitizing dye preferably has an absorption peak at 350 to 850 nm. Examples of such sensitizing dyes include spectral sensitizing dyes and the following dyes or pigments that absorb light from a light source and interact with a photopolymerization initiator.
Preferred spectral sensitizing dyes or dyes include polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thianes). Carbocyanine, oxacarbocyanine), merocyanines (eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), phthalocyanines ( For example, phthalocyanine, metal phthalocyanine), porphyrins (for example, tetraphenylporphyrin, central metal-substituted porphyrin), chlorophylls (for example, chlorophyll, chlorophyllin, central gold) Substituted chlorophyll), metal complexes, anthraquinones (e.g., anthraquinone), squaryliums (e.g., squarylium), and the like.

  Examples of more preferable spectral sensitizing dyes or dyes include styryl dyes described in JP-B-37-13034, cationic dyes described in JP-A-62-143044, and quinoxalinium described in JP-B-59-24147. Salts, new methylene blue compounds described in JP-A No. 64-33104, anthraquinones described in JP-A No. 64-56767, benzoxanthene dyes described in JP-A No. 2-1714, JP-A No. 2-226148 and special Acridines described in the respective publications of Kaihei 2-226149, pyrylium salts described in JP-B-40-28499, cyanines described in JP-B-46-42363, benzofuran dyes described in JP-A-2-63053, Conjugated ketone dyes described in JP-A-2-85858 and JP-A-2-216154 HirakiAkira 57-10605 described in JP-dye. Azocinnamylidene derivatives described in JP-B-2-30321, cyanine dyes described in JP-A-1-287105, JP-A-62-31844, JP-A-62-31848, JP-A-62-143043 Xanthene dyes described in Japanese Patent Publication Nos. JP-A Nos. 59-28325, merocyanine dyes described in JP-B No. 61-9621, and dyes described in JP-A No. 2-179433. The merocyanine dye described in JP-A-2-244050, the merocyanine dye described in JP-B-59-28326, the merocyanine dye described in JP-A-8-129257, the benzopyran dye described in JP-A-8-334897, and JP-A-2001-1000041 And styryl compounds described in JP-A-2003-221517.

  The addition amount range of the sensitizing dye is preferably from 0.1 to 50 mass%, more preferably from 0.5 to 30 mass%, particularly preferably from 1 to 20 mass%, based on the total solid content constituting the photopolymerization layer. It is.

<(C) Polymerizable compound>
The polymerizable compound that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is a compound having at least one terminal ethylenically unsaturated bond, preferably two or more. To be elected. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and a monofunctional or polyfunctional compound. A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or Also suitable are substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a tosyloxy group with monofunctional or polyfunctional alcohols, amines or thiols. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

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

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

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

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

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

  In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane 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 (II) to a polyisocyanate compound having two or more isocyanate groups. Compounds and the like.

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

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

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

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrene compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
Further, the selection and use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components in the photopolymerization layer (for example, binder polymer, initiator, colorant, etc.). In some cases, the compatibility can be improved by using a low-purity compound or by using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the substrate and the protective layer described later.
The addition polymerizable compound is preferably used in the range of 5 to 80% by mass, and more preferably 25 to 75% by mass with respect to the nonvolatile component in the photopolymerization layer. These may be used alone or in combination of two or more. In addition, the use method of the addition polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.

<(D) Binder polymer>
As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and polymers having film properties are preferred. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.
The binder polymer may have crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.
Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid where the ester or amide residue (R of -COOR or -CONHR) is Mention may be made of polymers having an ethylenically unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{bond, - (CH 2) n CR} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and — (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, Represents an alkoxy group or an aryloxy group, and R ¹ and R ² or R ³ may combine with each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadienyl. Represents a residue).
Specific examples of the ester _{residue, -CH 2 CH = CH 2,} ( described in JP Kokoku _{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.

  In the case of a binder polymer having crosslinkability, for example, free radicals (polymerization initiation radicals or growth radicals in the polymerization process of a polymerizable compound) are added to the crosslinkable functional group, and a polymerization chain of a polymerizable compound is formed directly between 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 to each other so that crosslinking between the polymer molecules occurs. Forms and cures.

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

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

  Examples of hydrophilic binder polymers include hydroxy groups, carboxyl groups, carboxylate groups, hydroxyethyl groups, polyoxyethyl groups, hydroxypropyl groups, polyoxypropyl groups, amino groups, aminoethyl groups, aminopropyl groups, and ammonium. Preferred are those having a hydrophilic group such as a group, an amide group, a carboxymethyl group, a sulfonic acid group, and a phosphoric acid group.

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

In the present invention, a binder polymer containing an ether group represented by — [CH ₂ — (CHR) _m —O] _n — in the molecule can also be used. Here, R represents a hydrogen atom or a methyl group, m is 1, 3 or 5, and n represents an integer of 1 to 20. n is preferably an integer of 1 to 8, more preferably an integer of 1 to 7, and most preferably an integer of 1 to 4.
Specific examples include homopolymers or copolymers of acrylates or methacrylates having the ether group in the side chain. Examples of the monomer to be copolymerized include the monomer having the crosslinkable group and other monomers in the description of the specific copolymer.
The hydrophilicity of this ether group is effective for obtaining good on-press developability.

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

(D) The content of the binder polymer is preferably 5 to 90% by mass, more preferably 5 to 80% by mass, and more preferably 10 to 70% by mass with respect to the total solid content of the photopolymerization layer. Is more preferable. Within this range, good image area strength and image formability can be obtained.
The polymerizable compound (C) and the binder polymer (D) are preferably used in an amount of 0.5 / 1 to 4/1 in terms of mass ratio ((C) / (D)).

<Microcapsules and microgels>
In the present invention, several modes can be used as a method for incorporating the above-mentioned photopolymerization layer constituent components (A) to (D) and other constituent components described later into the photopolymerization layer. One is a molecular dispersion type photopolymerization layer in which the constituent components are dissolved and applied in an appropriate solvent as described in, for example, JP-A-2002-287334. In another embodiment, as described in, for example, JP-A Nos. 2001-277740 and 2001-277742, all or part of the constituent components are encapsulated in microcapsules and contained in the photopolymerization layer. It is a capsule type photopolymerization layer. Further, in the microcapsule type photopolymerization layer, the constituent component can be contained outside the microcapsule. Here, it is preferable that the microcapsule type photopolymerization layer includes a hydrophobic constituent component in the microcapsule and a hydrophilic constituent component outside the microcapsule. Still another embodiment includes an embodiment in which the photopolymerization layer contains crosslinked resin particles, that is, microgel. The microgel may contain a part of the constituent component in and / or on the surface thereof. In particular, an embodiment in which a reactive microgel is formed by having a polymerizable compound on the surface thereof is particularly preferable from the viewpoint of image formation sensitivity and printing durability.
In order to obtain better on-press developability, the photopolymerization layer is preferably a microcapsule type or microgel type photopolymerization layer.

  As a method for encapsulating the above photopolymerization layer constituents into microcapsules or microgelling, it is possible to apply known methods.

  For example, as a method for producing microcapsules, US Pat. No. 2,800,547, US Pat. No. 2,800,498, a method using coacervation, US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, The method by the interfacial polymerization method found in US Pat. No. 42-446, the method by the precipitation of polymer found in US Pat. Nos. 3,418,250 and 3,660,304, the isocyanate found in US Pat. No. 3,796,669 Method using polyol wall material, method using isocyanate wall material found in US Pat. No. 3,914,511, urea found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802 -Formaldehyde or urea formaldehyde -A method using a resorcinol-based wall forming material, a method using a wall material such as melamine-formaldehyde resin, hydroxycellulose, etc. found in US Pat. No. 4,025,445, Japanese Patent Publication Nos. 36-9163 and 51-9079. In-situ method by monomer polymerization, British Patent No. 930422, US Pat. No. 3,111,407 Spray drying method, British Patent No. 952807, US Pat. No. 9,670,741 Although there is a cooling method, it is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Further, a compound having a crosslinkable functional group such as an ethylenically unsaturated bond capable of introducing a binder polymer may be introduced into the microcapsule wall.

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

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

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

<Surfactant>
In the present invention, it is preferable to use a surfactant in the photopolymerization layer in order to promote on-press developability at the start of printing and to improve the coated surface state. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.

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

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

  The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

  The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.

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

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

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

<Colorant>
In the present invention, various compounds other than these may be added as necessary. For example, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc. And dyes described in No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.
These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The amount added is preferably 0.01 to 10% by mass with respect to the total solid content of the image recording material.

<Bakeout agent>
In the photopolymerization layer of the present invention, a compound that changes color by an acid or a radical can be added to produce a printout image. As such a compound, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

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

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

  A suitable addition amount of the dye that changes color by an acid or a radical is 0.01 to 15% by mass relative to the solid content of the photopolymerization layer.

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

<Higher fatty acid derivatives, etc.>
In order to prevent polymerization inhibition due to oxygen, a higher fatty acid derivative such as behenic acid or behenamide is added to the photopolymerization layer of the present invention, and the surface of the photopolymerization layer is dried during the coating process. It may be unevenly distributed. The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass with respect to the total solid content of the photopolymerization layer.

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

<Inorganic fine particles>
The photopolymerization layer of the present invention may contain inorganic fine particles in order to improve the strength of the cured film in the image area and improve the on-press developability of the non-image area.
As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate or a mixture thereof can be preferably mentioned. Even if they are not photothermally convertible, they can be used for strengthening the film, enhancing interfacial adhesion by surface roughening, and the like.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 μm to 3 μm. Within the above range, it is possible to form a non-image portion excellent in hydrophilicity that is stably dispersed in the photopolymerization layer, sufficiently retains the film strength of the photopolymerization layer, and hardly causes stains during printing.
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 40% by mass or less, and more preferably 30% by mass or less, based on the total solid content of the photopolymerization layer.

<Low molecular hydrophilic compound>
The photopolymerizable layer of the present invention may contain a hydrophilic low molecular compound for improving on-press developability. Examples of the hydrophilic low-molecular compound include water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Examples thereof include organic carboxylic acids such as salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid and amino acids, and salts thereof.

<Formation of photopolymerization layer>
The photopolymerizable layer of the present invention is applied by preparing a coating solution by dispersing or dissolving the necessary components described above in a solvent. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like. However, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.
The photopolymerization layer of the present invention can be formed by preparing a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents, and repeating a plurality of coatings and dryings.

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

[Back coat layer]
After the surface treatment is performed on the support or after the undercoat layer is formed, a back coat can be provided on the back surface of the support, if necessary.
Examples of the back coat include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organometallic compounds or inorganic metal compounds described in JP-A-6-35174. A coating layer made of a metal oxide obtained in this manner is preferred. Of these, the use of silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4, etc. is inexpensive. It is preferable in that it is easily available.

[Protective layer]
The lithographic printing plate precursor according to the present invention is protected on the photopolymerization layer as necessary to impart oxygen barrier properties, prevent scratches in the photopolymerization layer, prevent ablation that occurs during high-illuminance laser exposure, and the like. A layer (overcoat layer) can be provided.
Usually, the exposure processing of a lithographic printing plate is carried out in the atmosphere. The image formation reaction in the photopolymerization layer caused by the exposure process can be inhibited by low molecular compounds such as oxygen and basic substances present in the atmosphere. The protective layer prevents low molecular compounds such as oxygen and basic substances from entering the photopolymerization layer, and as a result, suppresses image formation inhibition reaction in the air. Therefore, the property desired for the protective layer is to reduce the permeability of low molecular compounds such as oxygen, and furthermore, the transparency of light used for exposure is good, and the adhesiveness with the photopolymerization layer is excellent. And it can be easily removed in an on-press development process after exposure. The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and JP-B-55-49729.

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

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

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

  Suitable examples of the modified polyvinyl alcohol include compounds having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA124H, PVA-CS, PVA-CST, PVA-HC, PVA- 203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420, PVA-613, L-8 etc. are mentioned. Examples of the modified polyvinyl alcohol include KL-318, KL-118, KM-618, KM-118, SK-5102 having an anion-modified site, C-318, C-118, and CM-318 having a cation-modified site. M-205 and M-115 having terminal thiol modification sites, MP-103, MP-203, MP-102 and MP-202 having terminal sulfide modification sites, and ester modification sites with higher fatty acids HL-12E, HL-1203, and other reactive silane-modified R-1130, R-2105, R-2130, and the like.

The protective layer preferably contains a layered compound. The layered compound is a particle having a thin flat plate shape. For example, the following general formula A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂
[However, A is any one of K, Na, and Ca, B and C are any of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.

Examples of the natural mica include muscovite, soda mica, phlogopite, biotite and sericite. Synthetic mica includes non-swellable mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 ( _{Si 4 O 10) F 2,} Na or Li teniolite _{(Na, Li) Mg 2 Li} (Si 4 O 10) F 2, montmorillonite based Na or Li hectorite _{(Na, Li) 1/8 Mg 2} /5 Li Examples thereof include swelling mica such as _1/8 (Si ₄ O ₁₀ ) F ₂ . Synthetic smectites are also useful.

Of the above layered compounds, fluorine-based swellable mica, which is a synthetic layered compound, is particularly useful. That is, swellable clay minerals such as mica, montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, and metal atom substitution in the lattice is other than Significantly greater than viscous minerals. As a result, the lattice layer is deficient in positive charge, and Li ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts, sulfonium salts, etc. Adsorbs organic cation cations. These layered compounds swell with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swelling synthetic mica have this tendency.

As the shape of the layered compound, from the viewpoint of diffusion control, the thinner the better, the better the planar size as long as the smoothness of the coated surface and the transmittance of actinic rays are not impaired. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.
The average particle diameter of the layered compound is 1 to 20 μm, preferably 1 to 10 μm, particularly preferably 2 to 5 μm. When the particle diameter is smaller than 1 μm, the suppression of permeation of oxygen and moisture is insufficient and the effect cannot be exhibited sufficiently. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.
When the inorganic layered compound particles having such a large aspect ratio are contained in the protective layer, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor does not deteriorate due to changes in humidity, and the storage stability is excellent.

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

  As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers can be added. These activators can be added in an amount of 0.1 to 100% by mass relative to the (co) polymer.

  In order to improve the adhesion to the image area, for example, JP-A-49-70702 discloses an acrylic emulsion, water-insoluble vinylpyrrolidone-vinyl acetate in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesiveness can be obtained by mixing 20 to 60% by mass of a copolymer or the like and laminating on a photopolymerization layer. Any of these known techniques can be used in the present invention.

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

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

  This protective layer coating solution includes known anionic surfactants, nonionic surfactants, cationic surfactants, fluorosurfactants and water-soluble plasticizers for improving the physical properties of the coating. Additives can be added. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, you may add to this coating liquid the well-known additive for improving the adhesiveness with a photopolymerization layer and the temporal stability of a coating liquid.

  The protective layer coating solution thus prepared is applied on the photopolymerization layer provided on the support and dried to form the protective layer. The coating solvent can be appropriately selected in relation to the binder, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water. The method for applying the protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. . Specific examples of the protective layer include blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and bar coating.

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

[Support]
The support used for the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. Preferable supports include a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

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

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

  Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it becomes easy to improve hydrophilicity and secure adhesion between the photopolymerization layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Also, a transfer method in which the uneven shape is transferred with a roll provided with unevenness in the aluminum rolling step may be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

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

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. d m ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

〔exposure〕
As a light source for exposing the lithographic printing plate precursor according to the invention, a known light source can be used without limitation. The desirable wavelength of the light source is 300 nm to 1200 nm. Specifically, it is preferable to use various lasers as the light source, and among them, a semiconductor laser that emits infrared light having a wavelength of 760 nm to 1200 nm is preferably used.
The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like.
In addition, as other exposure beams for the lithographic printing plate precursor of the present invention, ultra-high pressure, high pressure, medium pressure, low pressure mercury lamps, chemical lamps, carbon arc lamps, xenon lamps, metal halide lamps, various visible and ultraviolet laser lamps Fluorescent lamps, tungsten lamps, sunlight, etc. can also be used.

〔printing〕
The lithographic printing method using the lithographic printing plate precursor according to the present invention is not particularly limited. For example, the lithographic printing plate precursor according to the present invention is imagewise exposed with a laser such as an infrared laser and then undergoes any development processing step. A method of printing by supplying oil-based ink and water-based component without any problem.
Specifically, after a lithographic printing plate precursor is exposed with a laser, it is mounted on a printing machine without passing through a development process, and after printing the lithographic printing plate precursor on a printing machine, a laser is used on the printing machine. And a method of printing without passing through a development processing step.

After the lithographic printing plate precursor is imagewise exposed with a laser, printing is performed by supplying an aqueous component and an oil-based ink without passing through a development processing step such as a wet development processing step. The photopolymerized layer cured by forming an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed area, the uncured photopolymerization layer is dissolved or dispersed and removed by the supplied aqueous component and / or oil-based ink, and a hydrophilic surface is exposed in the area. As a result, the aqueous component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the photopolymerized layer in the exposed area, and printing is started. Here, the aqueous component or oil-based ink may be supplied to the printing plate first, but the oil-based ink is first used in order to prevent the aqueous component from being contaminated by the unexposed photopolymerized layer. It is preferable to supply. As the aqueous component and oil-based ink, dampening water and printing ink for ordinary lithographic printing are used.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.

  Further, after the lithographic printing plate precursor of the present invention is imagewise exposed with a laser, a development treatment may be performed using a non-alkaline aqueous solution having a pH of 10 or less as a developer. As the non-alkaline aqueous solution that can be used here, for example, water alone or an aqueous solution containing water as a main component (containing 60% by mass or more of water) is preferable, and in particular, the composition is the same as that of generally known dampening water. The aqueous solution containing an aqueous solution or a surfactant (anionic, nonionic, cationic, etc.) is preferred. The pH of the developer is preferably from 2 to 10, more preferably from 3 to 9, and even more preferably from 5 to 9. .

The non-alkali aqueous solution that can be used as the developer may contain an organic acid, an inorganic acid, an inorganic salt, or the like.
Examples of organic acids include citric acid, acetic acid, succinic acid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malic acid, lactic acid, levulinic acid, p-toluenesulfonic acid, xylenesulfonic acid, phytic acid, and organic phosphonic acid. . The organic acid can also be used in the form of its alkali metal salt or ammonium salt. The content in the developer is preferably 0.01 to 5% by mass.

Examples of inorganic acids and inorganic salts include phosphoric acid, metaphosphoric acid, primary ammonium phosphate, secondary ammonium phosphate, primary sodium phosphate, secondary sodium phosphate, primary potassium phosphate, secondary potassium phosphate, Examples include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogen sulfate, nickel sulfate and the like. The content in the developer is preferably 0.01 to 5% by mass.

  Examples of the anionic surfactant that can be used in the developer used in the present invention include fatty acid salts, abietic acid salts, hydroxyalkane sulfonic acid salts, alkane sulfonic acid salts, dialkyl sulfosuccinic acid salts, linear alkylbenzene sulfonic acid salts, Branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamides Sodium salts, petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, fatty acid alkyl ester sulfate esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfates Ester salt, fatty acid monoglyceride sulfate ester, polyoxyethylene alkylphenyl ether sulfate ester salt, polyoxyethylene styryl phenyl ether sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkylphenyl ether phosphate Examples thereof include ester salts, partially saponified products of styrene-maleic anhydride copolymer, partially saponified products of olefin-maleic anhydride copolymer, and naphthalene sulfonate formalin condensates. Of these, dialkylsulfosuccinates, alkylsulfate esters and alkylnaphthalenesulfonates are particularly preferably used.

  The cationic surfactant that can be used in the developer used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

Nonionic surfactants that can be used in the developer used in the present invention include polyethylene glycol type higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide Adducts, higher alkylamine ethylene oxide adducts, fatty acid amide ethylene oxide adducts, fat and oil ethylene oxide adducts, polypropylene glycol ethylene oxide adducts, dimethylsiloxane-ethylene oxide block copolymers, dimethylsiloxane- (propylene oxide-ethylene oxide) Block copolymer, fatty acid ester of polyhydric alcohol glycerol, fatty acid ester of pentaerythritol, Bitoru and fatty acid esters of sorbitan, fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, fatty acid amides of alkanolamines.
These nonionic surfactants may be used alone or in combination of two or more. In the present invention, ethylene oxide adduct of sorbitol and / or sorbitan fatty acid ester, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, polyhydric alcohol Fatty acid esters are more preferred.

Moreover, from the viewpoint of stable solubility or turbidity in water, the nonionic surfactant used in the developer of the present invention preferably has an HLB (Hydrophile-Lipophile Balance) value of 6 or more, and 8 More preferably.
Furthermore, the ratio of the nonionic surfactant contained in the developer is preferably 0.01 to 10% by mass, and more preferably 0.01 to 5% by mass.
Also, acetylene glycol-based and acetylene alcohol-based oxyethylene adducts, fluorine-based and silicon-based surfactants can be used in the same manner.
As the surfactant used in the developer of the present invention, a nonionic surfactant is particularly suitable from the viewpoint of foam suppression.

The developer used in the present invention may contain an organic solvent. Examples of the organic solvent that can be contained here include aliphatic hydrocarbons (hexane, heptane, “Isopar E, H, G” (produced by Esso Chemical Co., Ltd.) or gasoline, kerosene, etc.), aromatic hydrocarbons, and the like. (Toluene, xylene, etc.), halogenated hydrocarbons (methylene dichloride, ethylene dichloride, trichlene, monochlorobenzene, etc.) and the following polar solvents.
Examples of polar solvents include alcohols (methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol monomethyl ether, 2-ethoxyethanol, diethylene glycol monoethyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, propylene glycol mono Ethyl ether, dipropylene glycol monomethyl ether, polyethylene glycol monomethyl ether, polypropylene glycol, tetraethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, methylphenyl carbinol, n-amyl alcohol, methyl amyl Alcoa Etc.), ketones (acetone, methyl ethyl ketone, ethyl butyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), esters (ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, methyl lactate, butyl lactate, ethylene glycol monobutyl) Acetate, propylene glycol monomethyl ether acetate, diethylene glycol acetate, diethyl phthalate, butyl levulinate, etc.) and others (triethyl phosphate, tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, etc.).

  When the organic solvent is insoluble in water, it can be used after being solubilized in water using a surfactant or the like. When the developer contains an organic solvent, the concentration of the solvent is preferably less than 40% by mass from the viewpoint of safety and flammability.

  In the developer used in the present invention, as a water-soluble polymer compound, soybean polysaccharide, modified starch, gum arabic, dextrin, fiber derivative (for example, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.) and modified products thereof, Pullulan, polyvinyl alcohol and its derivatives, polyvinyl pyrrolidone, polyacrylamide and acrylamide copolymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, styrene / maleic anhydride copolymer, etc. Can be contained.

  A well-known thing can be used for the said soybean polysaccharide, for example, there exists a brand name Soya Five (made by Fuji Oil Co., Ltd.) as a commercial item, and the thing of various grades can be used. What can be preferably used is one in which the viscosity of a 10% by mass aqueous solution is in the range of 10 to 100 mPa / sec.

As the modified starch, known ones can be used, and starch such as corn, potato, tapioca, rice and wheat is decomposed with acid or enzyme in the range of 5 to 30 glucose residues per molecule, and further in an alkali. It can be made by a method of adding oxypropylene or the like.
Two or more water-soluble polymer compounds can be used in combination. The content of the water-soluble polymer compound in the developer is preferably from 0.1 to 20% by mass, and more preferably from 0.5 to 10% by mass.

  In addition to the above, the developer used in the present invention may contain a preservative, a chelate compound, an antifoaming agent and the like.

  Preservatives include phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzisothiazolin-3-one, benztriazole derivatives, amiding anidine derivatives, quaternary ammonium salts, pyridine, Derivatives such as quinoline and guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3diol, 1,1-dibromo-1-nitro-2-ethanol, 1,1-dibromo-1-nitro-2-propanol and the like can be preferably used.

  Examples of the chelate compound include ethylenediaminetetraacetic acid, potassium salt thereof, sodium salt thereof; diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof; triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof, hydroxyethylethylenediaminetriacetic acid Nitrilotriacetic acid, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri (methylenephosphonic acid), potassium salt, sodium salt And organic phosphonic acids and phosphonoalkanetricarboxylic acids. An organic amine salt is also effective in place of the sodium salt and potassium salt of the chelating agent.

  As the antifoaming agent, a general silicon-based self-emulsifying type, emulsifying type, or nonionic surfactant having a HLB of 5 or less can be used. Silicon antifoaming agents are preferred. Among them, emulsification dispersion type and solubilization can be used.

The development processing with a non-alkaline aqueous solution in the present invention can be preferably carried out by an automatic processor equipped with a developer supply means and a rubbing member. As the automatic processor, for example, an automatic processor described in JP-A-2-220061 and JP-A-60-59351, which performs rubbing while conveying a lithographic printing plate precursor after image recording, Automatic processing for rubbing the lithographic printing plate precursor after image recording set on the cylinder described in the specifications of Japanese Patent No. 5148746, US Pat. No. 5,568,768 and British Patent No. 2297719 while rotating the cylinder Machine. Among these, an automatic processor using a rotating brush roll as the rubbing member is particularly preferable. In the present invention, the lithographic printing plate after the rubbing treatment can be optionally washed with water, dried and desensitized.
Although the temperature of the developer can be used at any temperature, it is preferably 10 ° C to 50 ° C.

  Hereinafter, although an example and a comparative example explain the present invention in detail, the present invention is not limited to these.

(Production of support)
In order to remove rolling oil on the surface of an aluminum plate (material 1050) having a thickness of 0.3 mm, a degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, and then the hair diameter was 0.3 mm. The aluminum surface was grained using three 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. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .

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

Next, a 0.5% by mass hydrochloric acid aqueous solution (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. and nitric acid electrolysis under the condition of an electric quantity of 50 C / dm ² when the aluminum plate is an anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying. The plate was provided with a direct current anodic oxide coating of 2.5 g / m ² at a current density of 15 A / dm ² using 15% by weight sulfuric acid (containing 0.5% by weight of aluminum ions) as an electrolytic solution, and then washed and dried. Body A. The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

[Example 1]
Formation of Undercoat Layer The following undercoat liquid (1) was bar-coated on the support prepared above, and then oven-dried at 100 ° C. for 60 seconds to form an undercoat layer having a dry coating amount of 10 mg / m ² .

Undercoat liquid (1)
Specific copolymer (1) (mass average molecular weight 40,000) (described in Table 1) 0.017 g
・ Methanol 9.00 g
・ Water 1.00g

Formation of Photopolymerization Layer and Protective Layer After coating the photopolymerization layer coating solution (1) having the following composition on the support on which the undercoat layer was formed, it was oven-dried at 100 ° C. for 60 seconds, and the dry coating amount A lithographic printing plate precursor was obtained by forming a 1.0 g / m ² photopolymerization layer. Subsequently, a protective layer coating solution (1) having the following composition is bar-coated on the photopolymerized layer 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. A lithographic printing plate precursor was obtained.

  The photopolymerization layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and microcapsule solution (1) immediately before coating.

Photosensitive solution (1)
-Binder polymer (1) 0.162g
・ Polymerization initiator (1) 0.100 g
・ Infrared absorber (1) 0.020 g
Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.385 g
・ Fluorosurfactant (1) 0.044g
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g
Microcapsule liquid (1)
・ Microcapsule synthesized as follows (1) 2.640 g
・ Water 2.425g

Protective layer coating solution (1)
-1.5g of the following inorganic particle dispersion (1)
・ Polyvinyl alcohol PVA105 0.06g
(Kuraray Co., Ltd., degree of saponification 98.5 mol%, degree of polymerization 500)
・ Polyvinylpyrrolidone K30 0.01g
(Made by Tokyo Chemical Industry Co., Ltd., molecular weight Mw = 40,000)
・ Copolymer of vinylpyrrolidone and vinyl acetate 0.01g
LUVITEC VA64W
(Manufactured by ISP, copolymerization ratio = 6/4)
・ Nonionic surfactant Emarex 710 0.01g
(Nippon Emulsion Co., Ltd.)
・ Ion-exchanged water 6.0g

Synthesis of Microcapsule (1) As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (manufactured by Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75 mass% ethyl acetate solution) 10 g, Aronix M-215 ( Toagosei Co., Ltd.) 6.00 g and Pionein A-41C (Takemoto Yushi Co., Ltd.) 0.12 g were dissolved in ethyl acetate 16.67 g. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 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 40 ° C. for 2 hours. The microcapsule solution thus obtained was diluted with distilled water so that the solid content concentration was 15% by mass. The average particle size was 0.2 μm.

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

[Examples 2 to 5]
An undercoat layer is formed in the same manner as in Example 1 except that the specific copolymer in the undercoat liquid (1) is replaced with the specific copolymer described in Table 1, and further the photopolymerization as in Example 1 is performed thereon. A lithographic printing plate precursor was obtained by forming a layer and a protective layer.
Example 6
The specific copolymer of the undercoat liquid (1) in Example 1 was replaced with the specific copolymer shown in Table 1, and the following microgel liquid (1) was used instead of the microcapsule liquid (1). A lithographic printing plate precursor was prepared in the same manner as in 1.

Microgel solution (1)
-Microgel (1) synthesized as follows: 2.640 g
・ Distilled water 2.425g

<Synthesis of Microgel (1)>
As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g and 0.1 g of Piionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the 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. The solid content concentration of the microgel solution thus obtained was diluted with distilled water so as to be 15% by mass. The average particle size was 0.2 μm.

[Examples 7 to 10]
A lithographic printing plate precursor was prepared in the same manner as in Example 6 except that the specific copolymer of the undercoat liquid (1) in Example 6 was replaced with the specific copolymer shown in Table 1. In Table 1, No shows the number attached | subjected to the exemplary compound, and the number attached | subjected to the repeating unit in a structural formula column shows a copolymerization ratio.

[Comparative Example 1]
A lithographic printing plate precursor was prepared in the same manner as in Example 1 except that the following copolymer (mass average molecular weight 40,000) was used instead of the specific copolymer (1), and Comparative Example 1 was obtained.

[Exposure and printing]
Each lithographic printing plate precursor obtained in the above-mentioned examples and comparative examples was exposed with a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser under the conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2400 dpi. The exposure image includes a thin line chart. The obtained exposed original plate was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without developing. Dampening water (EU-3 (Effect manufactured by Fuji Photo Film Co., Ltd.) / Water / isopropyl alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) After supplying dampening water and ink, 100 sheets were printed at a printing speed of 6000 sheets per hour. When the on-press development of the unexposed portion of the photopolymerization layer was completed on the printing press and the number of printing paper required until the ink was not transferred to the printing paper was measured as on-press developability, Even when the planographic printing plate precursor was used, a printed matter having no stain on the non-image area was obtained within 100 sheets.

[Evaluation of planographic printing plate precursor]
The lithographic printing plate obtained above was evaluated for stain resistance, neglected stain resistance, fine line reproducibility and printing durability by the following methods. The results are shown in Table 2.

(1) Anti-stain property The non-image part of the blanket was visually inspected after 10,000 sheets were printed. The anti-smudge property was evaluated in four grades: ◎, ○, Δ, and × from the side with a low level of dirt on the blanket.

(2) Leaving stain prevention The blanket of the non-image area after printing 10,000 sheets in the above anti-staining property evaluation, stopping printing, leaving the plate on the printing machine for 1 hour, and then starting printing again The soil was visually evaluated. The ability to prevent neglected stains was evaluated in four grades, ◎, ○, Δ, and ×, starting from the one with less dirt on the blanket. The results are shown in Table 1.

(3) Fine line reproducibility As described in the section of exposure and printing, after 100 sheets were printed and it was confirmed that a printed material having no ink stains in the non-image area was obtained, 500 sheets were continuously printed. . A thin line chart (10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 60, 80, 100 and 200 μm fine line exposed charts) of a total of 600 printed sheets with a 25X magnifier The fine line reproducibility was evaluated based on the fine line width that was observed and reproduced with ink without interruption.

(4) Printing durability As described above, after printing was performed in the evaluation of fine line reproducibility, printing was further continued. As the number of printed sheets was increased, the photopolymerization layer was gradually worn out and the ink receptivity was lowered, so that the ink density in the printing paper was lowered. Printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing.

  The above results show that the infrared laser-sensitive lithographic printing plate precursor according to the present invention shows good results in any of the items of anti-stain properties, anti-stain properties, thin line reproducibility and printing durability. The conventional lithographic printing plate precursor shown in the comparative example is a result of insufficient thin line reproducibility and printing durability, clearly showing that the present invention is effective.

Hereinafter, Example 15 shall be read as Reference Example 15.
[Examples 11 to 15]
Formation of undercoat layer The following undercoat liquid (2) was bar-coated on the support prepared as described above, followed by oven drying at 100 ° C. for 60 seconds to form an undercoat layer having a dry coating amount of 10 mg / m ² . .

Undercoat liquid (2)
Specific copolymer (described in Table 3) 0.017g
・ Methanol 9.00 g
・ Water 1.00g

Formation of Photopolymerization Layer and Protective Layer After the bar coating of the photopolymerization layer coating solution (2) having the following composition was applied on the above undercoat layer, it was oven-dried at 100 ° C. for 60 seconds, and the dry coating amount was 1.0 g / m. ² is formed, and a protective layer coating solution (2) having the following composition is applied thereon so that the dry coating amount is 0.5 g / m ^2, and is dried at 120 ° C. for 1 minute to be a lithographic plate A printing plate master was obtained.

Photopolymerization layer coating solution (2)
・ The following polymerization initiator (2) 0.2 g
・ The following sensitizing dye (1) 0.5 g
-Binder polymer (1) 6.0g
・ Polymerizable compound, isocyanuric acid EO-modified triacrylate 12.4 g
(M-315 manufactured by Toa Gosei Co., Ltd.)
・ Royco Crystal Violet 3.0g
-Thermal polymerization inhibitor, N-nitrosophenylhydroxylamine aluminum salt 0.1 g
・ Tetraethylammonium chloride 0.1g
・ Fluorine-based surfactant (1) 0.1g
・ Methyl ethyl ketone 70.0g

Protective layer coating solution (2)
Polyvinyl alcohol (saponification degree 95 mol%, polymerization degree 800) 40 g
・ Polyvinylpyrrolidone (molecular weight 50,000) 5g
・ Poly (vinyl pyrrolidone / vinyl acetate (1/1)) molecular weight of 75 g
・ 950g of water

[Comparative Example 2]
A lithographic printing plate precursor was prepared in the same manner as in Example 11 except that the following copolymer (mass average molecular weight 30,000) was used instead of the specific copolymer (3), and Comparative Example 2 was obtained.

[Examples 16 to 20]
Formation of undercoat layer The following undercoat liquid (3) was bar-coated on the support prepared as described above, followed by oven drying at 100 ° C. for 60 seconds to form an undercoat layer having a dry coating amount of 10 mg / m ² . .

Undercoat liquid (3)
Specific copolymer (described in Table 3) 0.017g
・ Methanol 9.00 g
・ Water 1.00g

Formation of Photopolymerization Layer and Protective Layer A lithographic printing plate is produced in the same manner as the production of the lithographic printing plate precursors 11 to 15 except that the photopolymerization layer coating solution (2) is changed to a photopolymerization layer coating solution (3) having the following composition. A printing plate master was obtained.

Photopolymerization layer coating solution (3)
・ The following polymerization initiator (3) 0.2 g
-Binder polymer (2) 3.0g
・ Polymerizable compound, isocyanuric acid EO-modified triacrylate 6.2 g
(M-315 manufactured by Toa Gosei Co., Ltd.)
・ Royco Crystal Violet 3.0g
-Thermal polymerization initiator, N-nitrosophenylhydroxylamine aluminum salt 0.1 g
・ Fluorine-based surfactant (1) 0.1g
・ Microcapsule (1) (in terms of solid content) 10.0 g
・ Methyl ethyl ketone 35.0g
・ 35.0 g of 1-methoxy-2-propanol
・ Water 10.0g

[Comparative Example 3]
A lithographic printing plate precursor was prepared in the same manner as in Example 16 except that the copolymer used in Comparative Example 1 was used for the undercoat layer, and Comparative Example 3 was obtained.

[Exposure and printing]
The planographic printing plate precursor was exposed with a 375 nm or 405 nm semiconductor laser under the conditions of an output of 2 mW, an outer drum with a peripheral length of 900 mm, a drum rotation speed of 800 rpm, and a resolution of 2400 dpi. The one pixel drawing time is as shown in Table 4.

  The exposed lithographic printing plate precursors are each mounted on a SOR-M cylinder manufactured by Heidelberg, without developing, and dampening water (EU-3 (Etchi solution manufactured by Fuji Photo Film Co., Ltd.) / Water / isopropyl alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.), and after supplying dampening water and ink, printing speed of 6000 sheets per hour Printed 100 sheets. Removal of the unexposed portion of the photopolymerized layer on the printing machine was completed, and a printed matter free from ink stains in the non-image portion was obtained.

[Evaluation of planographic printing plate precursor]
The anti-stain property, anti-stain property property, fine line reproducibility and printing durability were evaluated in the same manner as in Examples 1-10. Sensitivity and white light safety were evaluated as follows. The evaluation results are shown in Table 4.

(5) Sensitivity After printing 100 sheets and confirming that a printed matter without ink stains was obtained in the non-image area, 500 sheets were continuously printed. In the total 600th printed matter, the exposure amount with no unevenness in the ink density in the image area was measured as sensitivity.

(6) White light safety An unexposed lithographic printing plate precursor was placed under a white fluorescent lamp and placed under conditions where the amount of light was 400 lux on the surface of the lithographic printing plate precursor, and was exposed. The lithographic printing plate precursor exposed under the white light is mounted on the cylinder of the printing machine SOR-M manufactured by Heidelberg as described above, and after printing 100 sheets, exposure under a white fluorescent light that does not cause ink smearing is performed. Time was measured. The longer this time, the better the white light safety.

  From the above results, the conventional lithographic printing plate precursor shown in the comparative example is inadequate in any of the items of anti-stain properties, anti-stain properties, thin line reproducibility or printing durability. It is apparent that the ultraviolet laser-sensitive lithographic printing plate precursor according to the present invention is excellent in all of these items, and also has good sensitivity and white light safety.

Example 21
Formation of undercoat layer The following undercoat liquid (4) was applied onto the support prepared as described above by bar and then oven-dried at 100 ° C. for 60 seconds to form an undercoat layer having a dry coating amount of 10 mg / m ² . .

Undercoat liquid (4)
Specific copolymer (21) (mass average molecular weight 40,000) (described in Table 5) 0.017 g
・ Methanol 9.00 g
・ Water 1.00g

Formation of Photopolymerization Layer and Protective Layer A lithographic printing plate precursor was obtained by forming a photopolymerization layer and a protective layer on the undercoat layer in the same manner as in Example 1.

[Examples 22 to 25]
An undercoat layer was formed in the same manner as in Example 21 except that the specific copolymer in the undercoat liquid (4) was replaced with the specific copolymers listed in Table 5, and light was applied in the same manner as in Example 21. A lithographic printing plate precursor was obtained by forming a polymerization layer and a protective layer.

Example 26
A lithographic printing plate precursor was produced in the same manner as in Example 21, except that the specific copolymer of the undercoat liquid (4) in Example 21 was replaced with the specific copolymer described in Table 5.

Hereinafter, Example 27 shall be read as Reference Example 27.
[Examples 27 to 30]
A lithographic printing plate precursor was prepared in the same manner as in Example 21 except that the specific copolymer of the undercoat liquid (4) in Example 26 was replaced with the specific copolymers shown in Table 5.

[Comparative Example 4]
A lithographic printing plate precursor was prepared in the same manner as in Example 21 except that the following copolymer (mass average molecular weight 40,000) was used in place of the specific copolymer (21).

[Exposure and printing]
Each lithographic printing plate precursor obtained as described above was exposed in a Trendsetter 3244VX manufactured by Creo in the same manner as in Example 1, and the obtained exposed original plate was used in a printing machine SOR-M manufactured by Heidelberg. 100 prints were made. When the on-press developability was measured in the same manner as in Example 1, any lithographic printing plate precursor was used, and a printed matter having no stain on the non-image area was obtained within 100 sheets.

[Evaluation of planographic printing plate precursor]
The lithographic printing plate obtained above was evaluated for stain resistance, neglected stain resistance, fine line reproducibility and printing durability in the same manner as in Example 1. The results are shown in Table 6.

  As is clear from the above results, the infrared laser-sensitive lithographic printing plate precursor according to the present invention has good anti-staining properties and neglectability while maintaining good printing durability as compared with a comparative example having a conventional undercoat layer. Antifouling and fine line reproducibility are improved.

[Examples 31 to 35]
Formation of undercoat layer The following undercoat liquid (5) was bar-coated on the support prepared as described above, followed by oven drying at 100 ° C. for 60 seconds to form an undercoat layer having a dry coating amount of 10 mg / m ² . .

Undercoat liquid (5)
Specific copolymer (described in Table 7) 0.017g
・ Methanol 9.00 g
・ Water 1.00g

Formation of Photopolymerization Layer and Protective Layer A lithographic printing plate precursor was obtained by forming a photopolymerization layer and a protective layer on the undercoat layer in the same manner as in Example 11.

[Comparative Example 5]
A lithographic printing plate precursor was prepared in the same manner as in Example 31 except that the following copolymer (mass average molecular weight 30,000) was used instead of the specific copolymer (23), and Comparative Example 5 was obtained.

Hereinafter, Example 38 shall be read as Reference Example 38.
[Examples 36 to 40]
Formation of undercoat layer The following undercoat liquid (6) was bar-coated on the support prepared as described above, followed by oven drying at 100 ° C. for 60 seconds to form an undercoat layer having a dry coating amount of 10 mg / m ² . .

Undercoat liquid (6)
Specific copolymer (described in Table 7) 0.017g
・ Methanol 9.00 g
・ Water 1.00g

Formation of Photopolymerization Layer and Protective Layer A lithographic printing plate precursor was obtained by forming a photopolymerization layer and a protective layer on the undercoat layer in the same manner as in Example 16.

[Comparative Example 6]
A lithographic printing plate precursor was produced in the same manner as in Example 36, except that the copolymer of Comparative Example 4 was used instead of the specific copolymer (33) for the undercoat layer, and Comparative Example 6 was obtained.

[Exposure and printing]
The obtained lithographic printing plate precursor was exposed with a 375 nm or 405 nm semiconductor laser in the same manner as in the exposure and printing of the lithographic printing plate precursors of Examples 16 to 20, and 100 sheets were printed by a Heidelberg printing machine SOR-M. . Removal of the unexposed portion of the photopolymerized layer on the printing machine was completed, and a printed matter free from ink stains in the non-image portion was obtained. The one pixel drawing time in exposure is as shown in Table 8.

[Evaluation of planographic printing plate precursor]
The anti-stain property, anti-stain property property, fine line reproducibility, printing durability, sensitivity and white light safety were evaluated in the same manner as in the case of the lithographic printing plate precursors of Examples 11-20. The evaluation results are shown in Table 8.

  From the above results, in the ultraviolet laser-sensitive lithographic printing plate precursor according to the present invention, it is possible to prevent stains while maintaining good printing durability, sensitivity and white light safety as compared with the comparative example having a conventional undercoat layer. It can be seen that the property, the left-stain prevention property and the fine line reproducibility are improved.

Claims (8)

On a hydrophilic support, a lithographic printing plate precursor having a photopolymerizable layer of the undercoat layer and the laser light sensitivity, the undercoat layer is at least (a1) a repeating unit selected from the following formula (a2) a support surface the lithographic printing plate precursor copolymer that Yusuke including having a repeating unit having at least one functional group capable of interacting with.


The lithographic printing plate precursor as claimed in claim 1, wherein the copolymer has a mass average molecular weight of at least 20,000. The lithographic printing plate precursor as claimed in claim 1 or 2 , wherein the photopolymerizable layer contains an infrared absorber. The lithographic printing plate precursor as claimed in any one of claims 1 to 3, wherein the copolymer further comprises (a3) a repeating unit having at least one hydrophilic group. The lithographic printing plate precursor as claimed in claim 4, wherein the repeating unit (a3) having at least one hydrophilic group is a repeating unit represented by the following general formula (A3).

(In general formula (A3), R ₁ ~ R ₃ Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a halogen atom. A is an oxygen atom or NR ⁷ -Represents R ⁷ Represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. L ₁ Represents a linear linking group having 5 to 20 atoms constituting the main skeleton of the linking group. W represents a hydrophilic group selected from the groups represented by the following general formula. )

  In the above formula, M ₁ Represents a hydrogen atom, a metal atom, or an ammonium group, and R ₇ And R ₈ Each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.   The lithographic printing plate precursor as claimed in any one of claims 1 to 5, wherein the photopolymerization layer contains microcapsules or microgels. A lithographic printing plate precursor having an undercoat layer and a laser-sensitive photopolymerization layer on a hydrophilic support, the undercoat layer comprising at least (a1) a repeating unit having at least one ethylenically unsaturated bond; (A2) contains a copolymer having a repeating unit having at least one functional group that interacts with the support surface and (a3) a repeating unit having at least one hydrophilic group, and the repeating unit of (a3) is: A lithographic printing plate precursor comprising a repeating unit represented by the general formula (A3).

(In General Formula (A3), R _{1 to} R ₃ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. A represents an oxygen atom or NR ⁷ —, and R ⁷ represents hydrogen. An atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, L ₁ represents a linear linking group having 5 to 20 atoms constituting the main skeleton of the linking group, and W is the following general formula. Represents a hydrophilic group selected from the group represented.)

In the above formula, M ₁ represents a hydrogen atom, a metal atom, or an ammonium group, and R ₇ and R ₈ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms. The lithographic printing plate precursor according to any one of claims 1 to 7 is mounted on a printing press and imagewise laser-exposed, or after imagewise exposure with a laser and then mounted on a printing press, A lithographic printing method in which printing ink and fountain solution are supplied to the lithographic printing plate precursor to remove a laser unexposed portion of the photopolymerization layer and print.