JP5439282B2 - Planographic printing plate precursor and plate making method - Google Patents

Description

  The present invention relates to a lithographic printing plate precursor and a plate making method using the same. More specifically, the present invention relates to a lithographic printing plate precursor that can be directly made by laser image exposure and a plate making method of the lithographic printing plate precursor.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area, and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support is used. After exposure through a mask such as a film, development with an alkaline developer is performed to leave the image recording layer corresponding to the image area, and dissolve and remove the unnecessary image recording layer corresponding to the non-image area. And obtained a lithographic printing plate.

  Due to recent advances in this field, lithographic printing plates are now available with CTP (computer to plate) technology. That is, a lithographic printing plate can be obtained by scanning and exposing a lithographic printing plate precursor directly using a laser or a laser diode without a lith film, and developing it.

  Along with the above progress, problems related to the lithographic printing plate precursor have been changed to improvements in image formation characteristics, printing characteristics, physical characteristics and the like corresponding to the CTP technology. In addition, due to increasing interest in the global environment, environmental issues related to waste liquids associated with wet processing such as development processing have been highlighted as another issue related to lithographic printing plate precursors.

  For the above environmental problems, simplification and no processing of development or plate making are directed. As one simple plate making method, a method called “on-press development” is performed. That is, after the exposure of the lithographic printing plate precursor, conventional development is not performed, but it is mounted on a printing machine as it is, and unnecessary portions of the image recording layer are removed at the initial stage of a normal printing process.

  In the plate making operation as described above, a system using a lithographic printing plate precursor and a light source that can be handled in a bright room or under a yellow light is preferable from the viewpoint of ease of work. Solid state lasers such as semiconductor lasers and YAG lasers are used.

As a lithographic printing plate precursor that can be developed on the machine, for example, in Patent Document 1, an image recording layer (photosensitive layer) containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on a support. A planographic printing plate precursor is described.
In such an on-press development type lithographic printing plate precursor, conventionally, a support having a highly hydrophilic surface is used to enable development with a dampening solution (usually almost neutral) on the printing press. As a result, the image area was easily peeled off from the support by dampening water during printing, and sufficient printing durability was not obtained. On the other hand, if the support surface is made hydrophobic, the ink also adheres to the non-image area during printing, and printing stains occur. Thus, it is extremely difficult to achieve both printing durability and stain resistance, and further improvements are desired.

  In view of the above problems, in Patent Documents 2 and 3, a lithographic printing plate precursor having a laser-sensitive photopolymerization layer on a hydrophilic support and capable of forming an image without alkali development, the photopolymerization layer or other The layer of (a1) contains a copolymer having a repeating unit having at least one ethylenically unsaturated bond and (a2) a repeating unit having at least one functional group that interacts with the support surface. A characteristic lithographic printing plate precursor has been proposed, and it is said that a lithographic printing plate having excellent printing durability and stain resistance can be obtained.

  In Patent Document 4, at least one of a reactive group that can be directly chemically bonded to the surface of the support and a reactive group that can be chemically bonded to the surface of the support through a cross-linked structure on the support. It has a hydrophilic layer formed by chemically bonding a hydrophilic polymer having a seed and a partial structure having a positive charge and a negative charge on the surface of the support, and an image forming layer in this order. A lithographic printing plate precursor has been proposed, and it is said that a lithographic printing plate having excellent hydrophilicity and non-image area non-image area and excellent adhesion between the image area and the support is obtained.

  Further, in Patent Document 5, an undercoat layer which is a copolymer comprising (1) a phosphonic acid group and / or a phosphate group and (2) a group containing an acid group and / or an ethylene glycol or polyethylene glycol side chain on a support. A lithographic printing plate precursor comprising is proposed.

However, the lithographic printing plate precursors of Patent Documents 2 and 3 have insufficient stain resistance when used as printing plates, and use of a lithographic printing plate precursor whose time has elapsed after production causes stains ( That is, there was a problem that the stain resistance after aging was insufficient.
In addition, the lithographic printing plate precursor of Patent Document 3 described above cannot obtain sufficient results with respect to both the stain resistance before aging and the stain resistance after aging. Furthermore, in the hydrophilic polymer described in Patent Document 4, it is necessary to use a non-aqueous solvent during the polymerization reaction in order to introduce a reactive group capable of being chemically bonded to the support surface via a crosslinked structure into the polymer. There were restrictions on manufacturing conditions, etc., and the environmental load was large.
Further, Patent Document 5 has a problem that the stain resistance is insufficient.

JP 2002-287334 A Japanese Patent Laid-Open No. 2005-125749 JP 2006-239860 A JP 2008-213177 A Special table 2008-510634 gazette

  Accordingly, the object of the present invention is to make plate making directly by image recording with a laser and development on the machine, and it is difficult to stain at the time of printing, particularly after lapse of time (after preparing a lithographic printing plate precursor, An object of the present invention is to provide a lithographic printing plate precursor that can provide a lithographic printing plate that is excellent in stain resistance (until the original image is exposed to an image) and that has good printing durability.

As a result of intensive studies, the inventors have controlled the mass ratio of the repeating unit represented by the general formula (a1-2) to the repeating unit represented by the general formula (a1-1), so that the undercoat layer and the image recording are recorded. It has been found that it is possible to further improve the stain resistance at the time of printing, in particular, the stain resistance after aging, while maintaining the adhesion to the layer.
The present invention is as follows.

1. A lithographic plate having an image recording layer containing (A) a polymerization initiator, (B) an infrared-absorbing dye, and (C) a polymerizable compound, which can be removed by at least one of printing ink and dampening water on a support. In the printing plate precursor, an undercoat layer provided between the support and the image recording layer is (D) a repeating unit derived from a monomer represented by the following general formula (a1-1), the following general formula ( a repeating unit derived from the monomer represented by a1-2) and a repeating unit derived from the monomer represented by the general formula (a1-1), including a repeating unit having a hydrophilic group in the side chain, and a general formula ( The mass ratio of the repeating unit derived from the monomer represented by the general formula (a1-2) to the sum of the mass of the repeating unit derived from the monomer represented by a1-2) is 0.03 to 0.25. Characterized by containing a copolymer The lithographic printing plate precursor that.

Formula _{(a1-1) CH 2 = C (} R 1) COO (R 2 O) n P = O (OH) 2
Formula _{(a1-2) [CH 2 = C} (R 1) COO (R 2 O) n] 2 P = O (OH)

Wherein, R ₁ is each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ₂ each independently represent a branched alkylene group which may number 2-3 carbon, n represents each independently The integer of 1-10 is represented.

2. The repeating unit having a hydrophilic group in the side chain contained in the copolymer is (a2) a repeating unit containing an oxyalkylene structure in the side chain, and (a3) a repeating unit containing a zwitterionic structure in the side chain. 2. The lithographic printing plate precursor as described in 1 above, wherein the lithographic printing plate precursor is at least one repeating unit selected from the group consisting of:
3. The lithographic printing plate precursor as described in 1 or 2 above, wherein the copolymer further comprises (a4) a repeating unit containing an ethylenically unsaturated bond in a side chain.
4). In the copolymer, a general formula (for a sum of masses of a repeating unit derived from the monomer represented by the general formula (a1-1) and a repeating unit derived from the monomer represented by the general formula (a1-2) ( The lithographic printing plate precursor as described in any one of 1 to 3 above, wherein the mass ratio of the repeating units derived from the monomer represented by a1-2) is 0.03 or more and 0.10 or less. .
5. In the copolymer, the sum of the mass of the repeating unit derived from the monomer represented by the general formula (a1-1) and the repeating unit derived from the monomer represented by the general formula (a1-2) is 5. The lithographic printing plate precursor as described in any one of 1 to 4 above, which is 0.01 to 0.8 in terms of mass ratio with respect to the total mass of all repeating units constituting the coalescence.
6). The lithographic printing plate precursor according to any one of 1 to 5 above is imagewise exposed, and then at least one of printing ink and fountain solution is supplied on the printing machine to remove the unexposed portion of the image recording layer A method for making a lithographic printing plate, comprising:

  According to the present invention, it is possible to make a plate directly from digital data such as a computer by recording using a laser, in particular, on-machine development is possible, and it is excellent in stain resistance at the time of printing, particularly stain resistance after aging. In addition, a lithographic printing plate precursor having good printing durability and a plate making method thereof can be provided.

The lithographic printing plate precursor according to the invention is characterized in that the undercoat layer provided between the support and the image recording layer contains the following specific copolymer.
The specific copolymer has a repeating unit derived from the monomer represented by the general formula (a1-1), a repeating unit derived from the monomer represented by the general formula (a1-2), and a hydrophilic group as a side chain. The general formula (for the sum of the mass of the repeating unit derived from the monomer represented by the general formula (a1-1) and the repeating unit derived from the monomer represented by the general formula (a1-2) It contains a copolymer having a mass ratio of repeating units derived from the monomer represented by a1-2) of 0.03 to 0.25.
The specific copolymer, the elements and components of the lithographic printing plate precursor used in the present invention, and the plate making method are described in detail below.

[Specific copolymer]

Monomers of general formula (a1-1) and general formula (a1-2), and repeating units derived therefrom

[Monomers of general formula (a1-1) and general formula (a1-2)]
_{(A1-1) CH 2 = C (} R 1) COO (R 2 O) n P = O (OH) 2
_{(A1-2) [CH 2 = C} (R 1) COO (R 2 O) n] 2 P = O (OH)

Wherein, R ₁ is each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. More preferably, it is a hydrogen atom or a methyl group. R ₂ represents an alkylene group having 2 to 3 carbon atoms which may be independently branched. More preferred is —CH ₂ CH ₂ —. n represents the integer of 1-10 each independently. More preferably, it is an integer of 1-5.

  Specific examples of the monomers represented by the general formula (a1-1) and the general formula (a1-2) include the following structures.

The general formula (a1-2) represents the sum of the mass of the repeating unit derived from the monomer represented by the general formula (a1-1) and the repeating unit derived from the monomer represented by the general formula (a1-2). The mass ratio of the repeating unit derived from the monomer to be used is 0.03 to 0.25, and a range of 0.03 to 0.1 is more preferable.
That is, it is represented by the general formula (a1-2) with respect to the sum of the masses of the monomer represented by the general formula (a1-1) and the monomer represented by the general formula (a1-2) used for the synthesis of the specific copolymer. The mass ratio of the monomer to be used is 0.03 to 0.25, and a range of 0.03 to 0.1 is more preferable.
When the mass ratio is larger than 0.25, dark polymerization of the specific copolymer in the undercoat layer tends to be caused, and the stain resistance after the lapse of time is inferior. On the other hand, if the mass ratio is less than 0.03, the adhesion to the image recording layer is lowered and the printing durability is lowered.
The monomer represented by the general formula (a1-1) and the monomer represented by the general formula (a1-2) are polymerized to obtain the following (a1-1 ′), (a1-2 ′), and ( a1-2 ″) repeat unit is generated. When this mass ratio is greater than 0.25, it is presumed that dark polymerization is likely to occur because many repeating units (a1-2 ″) are generated.

Here, R ₁₁ , R ₁₂ and n in the above formula are synonymous with R ₁ , R ₂ and n in the general formulas (a1-1) and (a1-2), respectively.
That is, R ₁₁ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. More preferably, it is a hydrogen atom or a methyl group. R ₁₂ represents an alkylene group having 2 to 3 carbon atoms which may be branched. More preferred is —CH ₂ CH ₂ —. n represents an integer of 1 to 10. More preferably, it is an integer of 1-5.

  Moreover, the sum of the mass of the repeating unit derived from the monomer represented by the general formula (a1-1) and the repeating unit derived from the monomer represented by the general formula (a1-2) constitutes the specific copolymer. It is preferable that it is 0.01 or more and 0.8 or less by mass ratio with respect to the gross mass of all the repeating units. When the mass ratio is within this range, adhesion between the support and the image recording layer can be obtained, and sufficient printing durability can be achieved. Further, the hydrophilic component can be sufficiently contained, and it becomes easy to prevent the occurrence of stains during printing.

(Method of controlling the above mass ratio)
The general formula (for the sum of the mass of the repeating unit derived from the monomer represented by the general formula (a1-1) and the repeating unit derived from the monomer represented by the general formula (a1-2) in the specific copolymer ( The control of the mass ratio of the repeating unit derived from the monomer represented by a1-2) is carried out by controlling the monomer represented by the general formula (a1-1) and the general formula (at the time of polymerization). This can be done by controlling the ratio of the monomer represented by a1-2).

Phosphate esters mainly composed of phosphoric acid monoesters and / or phosphoric acid diesters are used in various fields such as polymerization catalysts, surfactants, metal binding solvents, and fiber antistatic agents.
Phosphoric esters are generally synthesized by an esterification reaction of phosphoric acid and alcohol, for example, reaction of diphosphorus pentoxide and alcohol, but it is not possible to selectively synthesize phosphoric acid monoesters and phosphoric acid diesters. Have difficulty. For this reason, in order to obtain a highly pure phosphoric acid monoester or phosphoric acid diester, it is necessary to separate them.

In JP-A-10-182673, an acidic phosphoric acid ester mixture containing phosphoric acid monoester and phosphoric acid diester as main components, water, a water-insoluble organic solvent and a basic compound are mixed and treated with acidic phosphoric acid. After the ester mixture is extracted into the aqueous layer, the aqueous layer is separated, and then the acid and water-insoluble organic solvent, or the acid, water-insoluble organic solvent and inorganic salt are mixed in the water layer while controlling the amount thereof. In addition, a method for producing an acidic phosphate ester characterized in that an acidic phosphate ester mixture in which the composition ratio of phosphate ester and phosphate diester is controlled is extracted into a water-insoluble organic solvent layer.
Japanese Patent Application Laid-Open No. 2003-146992 describes a method for producing an unsaturated group-containing phosphate ester monomer.
Japanese Patent Application Laid-Open No. 2008-13670 describes a polymerizable phosphate ester composition containing a specific phosphate monoester and a specific phosphate diester.

  In the present invention, an extraction step of mixing a phosphate ester mixture mainly composed of a phosphate monoester and a phosphate diester with neutral water and a non-halogen organic solvent, and extracting the phosphate monoester into an aqueous layer, In addition, the ratio of phosphate ester to phosphate diester can be adjusted by a purification method comprising a separation step of separating the aqueous layer and the organic layer.

(Purification method of phosphate ester)
The method for purifying a phosphoric acid ester according to the present invention comprises mixing a phosphoric acid ester mixture mainly composed of phosphoric acid monoester and phosphoric acid diester with neutral water and a non-halogen organic solvent. It includes an extraction step for extraction into an aqueous phase (also referred to as “aqueous layer”), and a separation step for separating the aqueous phase and organic phase (also referred to as “organic layer”).
The method for purifying a phosphoric acid ester according to the present invention comprises separating a phosphoric acid ester mixture mainly composed of phosphoric acid monoester and phosphoric acid diester, using neutral water and a non-halogen organic solvent, and performing liquid-liquid separation. This is a method in which phosphoric acid monoester is extracted on the aqueous phase side, separated and purified.

<Extraction process>
The method for purifying a phosphoric acid ester according to the present invention comprises mixing a phosphoric acid ester mixture mainly composed of phosphoric acid monoester and phosphoric acid diester with neutral water and a non-halogen organic solvent. An extraction step to extract into the aqueous phase.
There is no restriction | limiting in particular in the content ratio of the phosphoric acid monoester and phosphoric acid diester in the said phosphate ester mixture, What is necessary is just an arbitrary ratio. The phosphate ester mixture may contain one or more phosphate monoesters, and may contain one or more phosphate diesters. Further, the phosphate ester mixture may contain compounds (impurities) other than the phosphate monoester and phosphate diester.
The phosphoric ester mixture is mainly composed of phosphoric monoester and phosphoric diester, that is, the total amount of phosphoric monoester and phosphoric diester is 50% by mass with respect to the total mass of the phosphoric ester mixture. That's it.

The neutral water that can be used in the extraction step is not particularly limited as long as the pH is neutral (pH 6 to 8), but is preferably water having a pH of 6.5 to 7.5. More preferably, the water does not contain salt. The method for purifying a phosphate ester according to the present invention can be separated without changing the aqueous phase to acidic and / or alkaline, and by using neutral water, less phosphate ester is used. Even if it is not a stable compound (especially acidic or alkaline stable), it can be separated with good yield and purification efficiency.
Specific examples of neutral water that can be used in the extraction step include tap water, well water, ion-exchanged water, distilled water, and pure water. Ion exchange water, distilled water, and pure water are more preferable.
The “salt” is a compound in which a cation and an anion are ion-bonded, and includes an inorganic salt and an organic salt.
Needless to say, in the extraction step, after mixing with the phosphate ester mixture, the pH varies due to phosphate monoester, phosphate diester, and the like.

Non-halogen organic solvents that can be used in the extraction step include organic solvents that do not have halogen atoms and are incompatible with water, that is, water when mixed with water at an appropriate ratio. If it is a solvent which can form a phase and an organic phase, there will be no restriction | limiting in particular.
Preferred examples of the non-halogen organic solvent include carboxylic acid esters, ethers, ketones, and glycol ethers, and glycol ethers are more preferable.
Carboxylic acid esters include ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, n-hexyl acetate, 2-ethylhexyl acetate, ethyl propionate, propionic acid n-propyl, isopropyl propionate, n-butyl propionate, isobutyl propionate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3-ethoxy Ethyl propionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butanoate, methyl acetoacetate, ethyl acetoacetate, Methyl pyruvate And ethyl pyruvate and the like.
Examples of ethers include methyl t-butyl ether, diisopropyl ether, ethyl isoamyl ether, diisoamyl ether, and dibutyl ether.
Examples of ketones include methyl n-propyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, 2-heptanone, 3-heptanone, and 4-heptanone.

Glycol ethers include ethylene glycol dialkyl ethers, propylene glycol dialkyl ethers, diethylene glycol dialkyl ethers, dipropylene glycol dialkyl ethers, ethylene glycol monoalkyl ether acetates, propylene glycol monoalkyl ether acetates, diethylene glycol monoalkyl ether Preferred examples include acetates and dipropylene glycol monoalkyl ether acetates, and more preferred examples include ethylene glycol dialkyl ethers.
The glycol ether is preferably a compound having a hydrocarbon chain having 4 or more carbon atoms such as a butyl group or a butylene group, and more preferably a compound having a hydrocarbon chain having 4 to 8 carbon atoms. More preferably, it is a compound having a butyl group and / or a butylene group. In the case of the above-mentioned compound, the polarity as a solvent is moderate, and the degree of purification is more excellent.

  Specific examples of glycol ethers include ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, ethylene glycol monobutyl ether acetate, propylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol Monobutyl ether acetate can be preferably exemplified, and ethylene glycol dibutyl ether can be particularly preferably exemplified. When the solvent is used, the water-solubility is moderate and the separation and yield are excellent.

Moreover, as a non-halogen-type organic solvent which can be used for this invention, the solvent whose water solubility is 1-10 is mentioned preferably.
The “water solubility” in the present invention represents the amount of water (unit: g) that can be dissolved in 100 g of the non-halogen organic solvent at 25 ° C.
For example, ethyl acetate has a water solubility of 2.94, diethylene glycol dibutyl ether has a water solubility of 1.4, ethylene glycol monobutyl ether acetate has a water solubility of 1.6, and diethylene glycol monobutyl ether acetate has a water solubility of 1.6. The water solubility is 3.7, the water solubility of propyl acetate is 2.9, and the water solubility of isopropyl acetate is 1.9.

Among these organic solvents, the non-halogen organic solvents include ethyl acetate, methyl t-butyl ether, diethylene glycol dibutyl ether, 3-methoxybutyl acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, diisopropyl ether, and methyl. It is preferably at least one organic solvent selected from the group consisting of isobutyl ketone, and particularly preferably diethylene glycol dibutyl ether.
The non-halogen organic solvents can be used alone or in combination of two or more.
The non-halogen organic solvent that can be used in the present invention can also be referred to the new edition solvent pocket book (edited by the Synthetic Organic Chemistry Association, published in 1994).

The use ratio of neutral water and non-halogen organic solvent in the extraction step is not particularly limited as long as an aqueous phase and an organic phase can be formed, but in terms of mass ratio, water: solvent = 5: 1 to 1. It is preferably 1: 5, more preferably 2: 1 to 1: 2, and still more preferably 1.2: 1 to 1: 1.2. When the use ratio of neutral water and non-halogen organic solvent is close to 1: 1 by mass ratio, the balance between separability and yield is more excellent.
In the extraction step, the use ratio of the neutral water and the non-halogen organic solvent and the phosphate ester mixture is not particularly limited, but is a mass ratio of water and solvent: mixture = 10: 1 to 1: 1. It is preferable that it is 7: 1 to 1: 1. Although depending on the solubility of the phosphoric acid monoester and phosphoric acid diester used in water and in the solvent, the phosphoric acid ester purification method of the present invention separates a large amount of the phosphoric acid ester mixture with less water and a solvent. be able to.

The mixing method and extraction method that can be used in the extraction step are not particularly limited, and known methods can be used.
Any extraction method may be used as long as it can perform liquid-liquid extraction, and a method using a separatory funnel can be suitably exemplified.
Further, in the extraction step, the phosphoric acid ester mixture, neutral water and non-halogen organic solvent may be mixed by any method, for example, mixing in the above separatory funnel, You may mix using mixing means, such as a stirrer.
There is no restriction | limiting in particular in the liquid temperature at the time of extraction in the said extraction process, Extraction can be performed suitably at room temperature (for example, 10 to 30 degreeC). Moreover, you may heat and cool with respect to phosphate ester mixture, neutral water, a non-halogen-type organic solvent, and these liquid mixture as needed.
The mixing time and stirring speed in the extraction step are not particularly limited as long as the mixing time and stirring speed can be sufficiently mixed with the phosphate ester mixture, neutral water and a non-halogen organic solvent.

<Separation process>
The method for purifying a phosphate ester according to the present invention includes a separation step of separating the aqueous phase and the organic phase.
In the separation step, the aqueous phase containing the phosphoric acid monoester obtained in the extraction step and the organic phase composed of a non-halogen organic solvent as a main component are separated, but the separation means is not particularly limited. However, there are no particular limitations on the separation method, and a known separation method can be used.
Examples of the separation method include a method of separating the aqueous phase and the organic phase with a separatory funnel, and a method of removing the organic phase by suction or decantation.
In the separation step, when the water phase and the organic phase are separated, it is preferable that the interface between the water phase and the organic phase is clear. Further, in order to stabilize the interface between the aqueous phase and the organic phase and form a clear interface, it is preferable to leave a liquid obtained by mixing a phosphate ester mixture, neutral water and a non-halogen organic solvent. . Although there is no restriction | limiting in particular as stationary time, 30 seconds-1 hour can be illustrated.
The liquid temperature at the time of separation in the separation step is not particularly limited, but the preferable liquid temperature is the same as the preferable liquid temperature at the time of extraction in the extraction step.

  In the method for purifying a phosphate ester of the present invention, the extraction step and the separation step may be performed only once or may be repeated twice or more, but the extraction step and the separation step are performed twice or more. Is preferable, and it is more preferable to carry out 2 to 5 times. Separation can be easily improved by performing the extraction step and the separation step a plurality of times.

In the method for purifying phosphate ester according to the present invention, a large amount of phosphate monoester is extracted in the aqueous phase obtained by separation, and a large amount of phosphate diester is extracted in the organic phase obtained by separation. Is done.
The content of the phosphoric diester in the aqueous phase obtained in the separation step is preferably 25 mol% or less, more preferably 10 mol% or less with respect to the content of the phosphoric monoester. More preferably, it is 6 mol% or less.
In particular, the aqueous phase containing a phosphoric acid monoester having an ethylenically unsaturated group obtained by the method for purifying a phosphoric acid ester according to the present invention is prepared as an aqueous solution containing a phosphoric acid monoester having an ethylenically unsaturated group. Can be suitably used as it is.
Moreover, the phosphoric acid monoester or the phosphoric acid diester obtained in the method for purifying a phosphoric acid ester of the present invention may be isolated by a known method, if desired, or another purification method. Purification may be performed by

(Method for producing polymer)
The method for producing a polymer of the present invention comprises a repeating unit represented by the general formula (a1-1) and a repeating unit represented by the general formula (a1-2) obtained by the method for purifying a phosphate ester of the present invention. It includes a polymerization step introduced by copolymerization.

In the polymerization step, it is preferable to perform polymerization or copolymerization using a polymerization initiator.
As the polymerization initiator that can be used in the present invention, known polymerization initiators can be used without limitation. Specifically, for example, azo compounds, inorganic peroxides, organic peroxides, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boron compounds, disulfone compounds, oxime ester compounds, onium salt compounds, iron arene complexes , Trihalomethyl compounds, and carbonyl compounds. Moreover, as a polymerization initiator, a radical polymerization initiator is preferable.
Among them, a water-soluble polymerization initiator that can be used for a polymerization reaction in an aqueous phase is preferable, a water-soluble azo compound, a water-soluble inorganic peroxide, and a water-soluble organic peroxide are more preferable, and a water-soluble azo compound. Is particularly preferred.
A polymerization initiator may be used individually by 1 type, or may use 2 or more types together.

  The amount of the polymerization initiator used in the polymerization step is not particularly limited as long as it can be polymerized, but is preferably 0.001 to 20 mol% when the total amount of the polymerizable compound is 100 mol%. More preferably, the content is 0.01 to 10 mol%, and more preferably 0.05 to 5 mol%.

The polymerization in the polymerization step may be performed in an aqueous medium, in an organic solvent, or in the absence of a solvent, but is preferably performed in an aqueous medium. By carrying out in an aqueous medium, an aqueous phase containing a phosphoric acid monoester having an ethylenically unsaturated group obtained by the method for purifying a phosphoric acid ester of the present invention can be easily used.
Examples of the aqueous medium that can be used in the polymerization step include water and alcohols. These may be used individually by 1 type and may use 2 or more types together.
The aqueous medium may contain a water-miscible organic solvent. Examples of the water-miscible organic solvent include acetone and acetic acid, and may contain the non-halogen organic solvent described above.

The reaction temperature and reaction time in the polymerization step are not particularly limited, and may be appropriately selected in consideration of the ethylenically unsaturated compound used, the medium, the polymerization method, the progress of the reaction, the desired physical property value of the polymer, and the like. Good.
Although there is no restriction | limiting in particular as a polymerization method in the said superposition | polymerization process, The method of slowly dripping the phosphoric acid monoester containing solution and polymerization initiator solution which have an ethylenically unsaturated group in an aqueous medium can illustrate preferably.
In addition, the polymer obtained by the method for producing a polymer of the present invention may be isolated or purified as necessary, or may be used as it is as a material for a lithographic printing plate surface treatment agent, for example.
The phosphate group in the repeating unit derived from the phosphate monoester having an ethylenically unsaturated group in the polymer may be a phosphate group that forms a salt. The counter cation forming the salt may be a monovalent cation or a divalent or higher cation, and includes known metal cations and organic cations.

Repeating unit having hydrophilic group in side chain In the present invention, the hydrophilic group means a sulfonic acid group (—SO ₃ H) and a salt thereof (—SO ₃ M (where M is a counter cation other than proton (H ⁺ )) )), A carboxylic acid group (—COOH) and a salt thereof (—COOM (where M represents a counter cation other than proton (H ⁺ ))), an amide group (—CONR— (where R is Represents a hydrogen atom or an organic group))), an oxyalkylene structure, and at least one group or structure selected from the group consisting of zwitterionic structures. A sulfonic acid group and a salt thereof, an oxyalkylene structure, and a group or structure having a zwitterionic structure are preferable, and a repeating unit having an oxyalkylene structure and a zwitterionic structure is more preferable.
Preferable examples of the sulfonic acid group and its salt include 2-acrylamido-2-methylpropanesulfonic acid or sodium salt, potassium salt, and ammonium salt of sulfonic acid.

  Below, the more preferable oxyalkylene structure and the repeating unit which has a zwitterionic structure are described.

(A2) Repeating unit having an oxyalkylene structure The specific copolymer of the present invention preferably has (a2) The oxyalkylene structure in the repeating unit having an oxyalkylene structure in the side chain is represented by the following general formula (a2-1) It is preferable that it is a structure represented by these.

[In General Formula (a2-1), R ²¹ represents a hydrogen atom or an alkyl group. R ²² represents a hydrogen atom, an alkyl group, or an aryl group. a represents an integer of 1 to 5. l represents an integer of 2 to 150. Y ² represents a single bond or a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Represent. * Represents a site connected to the main chain of the copolymer. ]

In general formula (a2-1), examples of the alkyl group represented by R ²¹ and R ²² are each independently a methyl group, an ethyl group, a propyl group, an octyl group, an isopropyl group, a t-butyl group, or an isopentyl group. Group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group and the like.
Examples of the aryl group represented by R ²² include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.
R ²¹ is most preferably a hydrogen atom, and R ²² is preferably a hydrogen atom or a methyl group, more preferably a methyl group. a represents preferably 1 or 2 and most preferably 1 from the viewpoint of soiling properties.
l represents an integer of 2 to 150, and is preferably 9 to 150, more preferably 9 to 100, and still more preferably 20 to 100, from the viewpoint of dirtiness.

Y ² represents a single bond or a divalent linking group selected from the group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Represent.

Specific examples of Y ² composed of the above combinations are given below. In the following examples, the left side is bonded to the main chain.
L1: -CO-O-divalent aliphatic group-
L2: —CO—O—divalent aromatic group—
L3: -CO-NH-divalent aliphatic group-
L4: —CO—NH—divalent aromatic group—
L5: -CO-divalent aliphatic group-
L6: —CO—divalent aromatic group—
L7: -CO-divalent aliphatic group-CO-O-divalent aliphatic group-
L8: -CO-divalent aliphatic group-O-CO-divalent aliphatic group-
L9: -CO-divalent aromatic group-CO-O-divalent aliphatic group-
L10: -CO-divalent aromatic group-O-CO-divalent aliphatic group-
L11: -CO-divalent aliphatic group-CO-O-divalent aromatic group-
L12: -CO-divalent aliphatic group-O-CO-divalent aromatic group-
L13: -CO-divalent aromatic group-CO-O-divalent aromatic group-
L14: -CO-divalent aromatic group-O-CO-divalent aromatic group-
L15: -CO-O-divalent aromatic group-O-CO-NH-divalent aliphatic group-
L16: -CO-O-divalent aliphatic group-O-CO-NH-divalent aliphatic group-
L17: -CO-O-

Here, 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, still more preferably 1 to 12, and still more 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 hydroxy group, a carboxy 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 above divalent aromatic group means an arylene group which may have a substituent. Specific examples include a substituted or unsubstituted phenylene group, naphthalene group, and anthrylene group. Of these, a phenylene group is preferable.
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.

Y ² is most preferably a linking group represented by L17. In the most preferred combination of Y ² , R ²¹ and R ²² , Y ² is L17, R ²¹ is a hydrogen atom, and R ²² is a methyl group.
Specific examples of the oxyalkylene structure include the following. In specific examples, the n value including a decimal number indicates an average value of the number of repetitions in a mixture having a different number of oxyalkylene repetitions.

  In the present invention, the repeating unit having a polyoxyalkylene structure is preferably represented by the following (A2).

In the above formula, R ^{201 to} R ²⁰³ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. J is a structure represented by the general formula (a2-1) described above, and a preferred embodiment is the same as the embodiment of the general formula (a2-1). Specific examples include the following structures.

  The ratio of the repeating unit (a2) having an oxyalkylene structure in the side chain in the specific copolymer in the present invention is based on all repeating units constituting the specific copolymer from the viewpoint of on-press development property and soiling property. The range is preferably 5 to 95% by mass, more preferably 20 to 80% by mass, and most preferably 20 to 60% by mass.

(A3) Repeating unit having zwitterionic structure in side chain The specific copolymer of the present invention preferably has a non-image part support surface to make it highly hydrophilic (a3) zwitterionic structure The side chain having a zwitterionic structure in the repeating unit having a side chain is preferably represented by the following general formula (a3-1) or (a3-2).

[In the general formula (a3-1), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and R ³¹ and R ³² represent They may be connected to each other to form a ring structure, L ³¹ represents a linking group, and A ⁻ represents a structure having an anion. Y ³ represents a divalent linking group linked to the main chain of the copolymer. * Represents a site connected to the main chain of the copolymer. ]

The ring structure formed by connecting R ³¹ and R ³² to each other may have a heteroatom such as an oxygen atom, and is preferably a 5- to 10-membered ring, more preferably a 5- or 6-membered ring.
The carbon number of R ³¹ and R ³² is preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and more preferably 1 to 15 carbon atoms, including the carbon number of the substituent which may be described later. Particularly preferred, C1-C8 is most preferred.

Examples of the alkyl group represented by R ³¹ and R ³² include methyl group, ethyl group, propyl group, octyl group, isopropyl group, t-butyl group, isopentyl group, 2-ethylhexyl group, 2-methylhexyl group, A cyclopentyl group etc. are mentioned.
Examples of the alkenyl group represented by R ³¹ and R ³² include vinyl group, allyl group, prenyl group (for example, dimethylallyl group, geranyl group, etc.), oleyl group and the like.
Examples of the alkynyl group represented by R ³¹ and R ³² include ethynyl group, propargyl group, trimethylsilylethynyl group and the like.
Examples of the aryl group represented by R ³¹ and R ³² include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group. Furthermore, examples of the heterocyclic group include a furanyl group, a thiophenyl group, and a pyridinyl group.

  These groups may further have a substituent. Examples of the substituent include halogen atom (F, Cl, Br, I), hydroxy group, carboxy group, amino group, cyano group, aryl group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxy Examples include a carbonyl group, an acyloxy group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, and a diarylamino group.

As R ³¹ and R ³² , from the viewpoints of effects and availability, particularly preferred examples include a hydrogen atom, a methyl group, and an ethyl group.

The divalent linking group represented by Y ³ consists of a single bond, —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. Represents a divalent linking group selected from the group;

Specific examples of ^{Y 3} comprising a combination of the above can be mentioned the same as the L1~L17 of ^{Y 2.}

Among them, Y ³ is preferably a single bond, —CO—, a divalent aliphatic group, a divalent aromatic group, or the above L1 to L4. Further, from the viewpoint of stain resistance, Y ³ is more preferably L1 or L3, and even more preferably L3. Further, the divalent aliphatic group represented by L3 is preferably a linear alkylene group having 2 to 4 carbon atoms, and most preferably a linear alkylene group having 3 carbon atoms in terms of synthesis.

L ³¹ represents a linking group, and is preferably a linking group comprising —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and a combination thereof, The carbon number is 30 or less including the carbon number of the substituent which may be described later. For example, an alkylene group (preferably having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms) and an arylene group such as a phenylene group or a xylylene group (preferably having 5 to 15 carbon atoms, more preferably 6 to 6 carbon atoms). 10). Specific examples include the following linking groups.

Among these, from the viewpoint of stain resistance, L ³¹ is preferably a linear alkylene group having 3 to 5 carbon atoms, more preferably a linear alkylene group having 4 or 5 carbon atoms, and a linear alkylene group having 4 carbon atoms being preferred. Most preferred.

In addition, these coupling groups may further have a substituent.
Examples of the substituent include halogen atom (F, Cl, Br, I), hydroxy group, carboxy group, amino group, cyano group, aryl group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxy Examples include a carbonyl group, an acyloxy group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, and a diarylamino group.

In the general formula (a3-1), A ⁻ preferably represents a carboxylate, a sulfonate, a phosphonate, or a phosphinate.
Specific examples include the following anions.

From the standpoint of stain resistance, A ^- and most preferably is sulfonate. Further, in the formula (a3-1), L ³¹ is a linear alkylene group having 4 or 5 carbon atoms, and A ⁻ is a combination of sulfonate, and L ³¹ is a linear alkylene group having 4 carbon atoms, A combination of A ⁻ and sulfonate is most preferable.

Y ³ is L1 or L3 above, R ³¹ and R ³² are an ethyl group or a methyl group, L ³¹ is a linear alkylene group having 4 or 5 carbon atoms, and A ⁻ is a sulfonate group. .
Further, Y ³ is L3, and R ³¹ and R ³² are methyl groups, L ³¹ is a linear alkylene group having 4 carbon atoms, and A ⁻ is a combination of sulfonates.
Specifically, the following structural formula is preferable.

In the general formula (a3-2), L ³² represents a linking group, and preferably —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and the like. Selected from the group consisting of Specific examples and preferred examples thereof are the same as the linking group represented by L ³¹ described above.
Y ³ has the same meaning as Y ^{3 in} formula (a3-1), and preferred examples thereof are also the same.
E ⁺ represents a structure having a cation, and preferably represents a structure having ammonium, phosphonium, iodonium, or sulfonium. A structure having ammonium or phosphonium is more preferable, and a structure having ammonium is particularly preferable. Examples of structures having a cation include trimethylammonio group, triethylammonio group, tributylammonio group, benzyldimethylammonio group, diethylhexylammonio group, (2-hydroxyethyl) dimethylammonio group, pyridinio group, N-methylimidazolio group, N-acridinio group, trimethylphosphonio group, triethylphosphonio group, triphenylphosphonio group and the like can be mentioned.
In the most preferable combination of L ³² , Y ³ and E ⁺ , L ³² is an alkylene group having 2 to 4 carbon atoms, Y ³ is L 1 or L 3, and E ⁺ is a trimethylammonio group or triethylammoni group. Oh group.
Specifically, the following structures can be mentioned.

  In the present invention, the repeating unit having a zwitterionic structure is preferably represented by the following (A3).

In the formula, R ^{301 to} R ³⁰³ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. G represents a side chain having a zwitterionic structure, and is preferably a structure represented by the general formula (a3-1) or (a3-2). Preferred examples and combinations of the general formulas (a3-1) and (a3-2) are the same as those described above.

  A particularly preferable side chain G in (A3) is a structure represented by the general formula (a3-1). Specific examples include the following structures.

  The ratio of the repeating unit having the (A3) zwitterionic structure in the specific copolymer in the present invention is 5.0 to 95 with respect to all repeating units constituting the specific copolymer from the viewpoint of stain resistance. It is preferably in the range of mass%, more preferably in the range of 5 to 80 mass%, still more preferably in the range of 10.0 to 60 mass%, and further considering printing durability, 10. 0-45 mass% is especially preferable.

(A4) Repeating unit having radically polymerizable reactive group in side chain The specific copolymer in the present invention is a repeating unit having (a4) a radically polymerizable reactive group in the side chain from the viewpoint of improving printing durability. It is preferable to have. Here, as preferable examples of the radical polymerizable reactive group, addition-polymerizable unsaturated bond groups (for example, (meth) acryloyl group, (meth) acrylamide group, allyl group, vinyl group, vinyloxy group, alkynyl group, etc.) ) And functional groups capable of chain transfer (such as mercapto groups). Among these, from the standpoint of printing durability, an unsaturated bond group capable of addition polymerization is preferable, and a methacryl group is most preferable. Here, the (meth) acrylic group represents an acrylic group or a methacrylic group.

  The radical-polymerizable reactive group includes (a) a urethanization reaction using a hydroxyl group on the polymer side chain and an isocyanate having a radical polymerization-reactive group, and (b) a hydroxyl group on the polymer side chain, and a radical polymerization reactivity. An esterification reaction using a carboxylic acid having a group, a carboxylic acid halide, a sulfonic acid halide, or a carboxylic acid anhydride, (c) a carboxy group of a polymer side chain or a salt thereof, and an isocyanate having a radical polymerization reactive group. Reaction used, (d) esterification reaction using a carbonyl halide, carboxy group or salt thereof on the polymer side chain, and an alcohol having a radical polymerization reactive group, (e) a carbonyl halide group on the polymer side chain An amidation reaction using a carboxy group or a salt thereof and an amine having a radical polymerization reactive group, (f) poly An amidation reaction using an amino group on the side chain and a carboxylic acid having a radical polymerization reactive group, a carboxylic acid halide, a sulfonic acid halide, or a carboxylic anhydride, and (g) an epoxy group on the polymer side chain , A ring-opening reaction with various nucleophilic compounds having a radical polymerization reactive group, (h) an etherification reaction between a haloalkyl group on the polymer side chain and an alcohol having a radical polymerization reactive group. it can.

  As a side chain which has a radically polymerizable reactive group, the structure represented by the following general formula (a4-1) is preferable.

In the general formula (a4-1), R ^{41 to} R ⁴³ each independently represents a hydrogen atom, an alkyl group, or an aryl group. In General Formula (a4-1), Y ⁴ represents a single bond, or a group consisting of —CO—, —O—, —NH—, a divalent aliphatic group, a divalent aromatic group, and combinations thereof. It represents a divalent linking group selected from the above. Specific examples of comprising the combination Y ⁴ below. In the following examples, the left side is bonded to the main chain, and the right side is bonded to the ethylenically unsaturated bond.

L19: -CO-NH-divalent aliphatic group -O-CO-
L20: -CO-divalent aliphatic group -O-CO-
L23: -CO-O-divalent aliphatic group -O-CO-
L24: -Divalent aliphatic group -O-CO-
L25: -CO-NH-divalent aromatic group -O-CO-
L26: -CO-divalent aromatic group -O-CO-
L27: -Divalent aromatic group -O-CO-
L28: -CO-O-divalent aliphatic group -CO-O-divalent aliphatic group -O-CO-
L29: -CO-O-divalent aliphatic group -O-CO-divalent aliphatic group -O-CO-
L30: -CO-O-divalent aromatic group -CO-O-divalent aliphatic group -O-CO-
L31: -CO-O-divalent aromatic group -O-CO-divalent aliphatic group -O-CO-
L32: -CO-O-divalent aliphatic group -CO-O-divalent aromatic group -O-CO-
L33: -CO-O-divalent aliphatic group -O-CO-divalent aromatic group -O-CO-
L34: -CO-O-divalent aromatic group -CO-O-divalent aromatic group -O-CO-
L35: -CO-O-divalent aromatic group -O-CO-divalent aromatic group -O-CO-
L36: -CO-O-divalent aromatic group -O-CO-NH-divalent aliphatic group -O-CO-
L37: -CO-O-divalent aliphatic group -O-CO-NH-divalent aliphatic group -O-CO-
L38: -CO-NH-divalent aliphatic group -O-CO-NH-divalent aliphatic group -O-CO-
The above divalent aliphatic group and divalent aromatic group are the same as those described above.

Of these preferred as Y ⁴ are L19, L23, L37, L38. More preferably, they are L19 and L37.
Specific examples of the structure represented by the general formula (a4-1) include the following structures.

  The repeating unit (a4) having at least one radical polymerizable reactive group is preferably a repeating unit represented by the following general formula (A4).

In General Formula (A4), R ^{401 to} R ⁴⁰³ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom. T represents a structure of a side chain having a radically polymerizable reactive group, preferably a structure represented by the general formula (a4-1), and a preferred embodiment is the same as the embodiment of the general formula (a4-1). is there. Specific examples include the following structures.

  In the specific copolymer, it is preferable that the repeating unit having such a (a4) radical polymerizable reactive group in the side chain is contained in an amount of 1 to 50% by mass per unit mass of the specific copolymer. % Is more preferable, and 1 to 20% by mass is most preferable.

  Although the specific copolymer in the present invention can be synthesized by a known method, a radical polymerization method is preferably used for the synthesis. General radical polymerization methods include, for example, New Polymer Experiments 3 (Polymer Society, edited by Kyoritsu Publishing, published on March 28, 1996), Polymer Synthesis and Reaction 1 (Polymer Society, edited by Kyoritsu Publishing, 1992). Published in May, 19), New Experimental Chemistry Course 19, Polymer Chemistry (I) (Edited by The Chemical Society of Japan, Maruzen, published on November 20, 1980), Materials Engineering Course, Synthetic Polymer Chemistry (Tokyo Denki University Press, (Issued in September 1995), etc., and these can be applied.

  The specific copolymer may be a copolymer having other repeating units other than the above-mentioned repeating units. Examples of the monomer that can be copolymerized with the specific copolymer include acrylic acid esters, methacrylic acid esters, N, N-2 substituted acrylamides, N, N-2 substituted methacrylamides, styrenes, and acrylonitrile. And monomers selected from methacrylonitriles.

Specifically, as the acrylate ester, alkyl acrylate (the alkyl group having 1 to 20 carbon atoms is preferable, for example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic Amyl acid, ethyl hexyl acrylate, octyl acrylate, tert-octyl acrylate, chloroethyl acrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, glycidyl acrylate Benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, etc.), aryl acrylate (for example, phenyl acrylate, etc.) ).
As the methacrylic acid esters, alkyl methacrylates (preferably those having 1 to 20 carbon atoms in the alkyl group, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate) , Chlorobenzyl methacrylate, octyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, glycidyl methacrylate, furfuryl methacrylate, Tetrahydrofurfuryl methacrylate etc. ), Aryl methacrylate (for example, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, etc.).
Examples of styrenes include styrene, alkyl styrene (for example, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, isopropyl styrene, butyl styrene, hexyl styrene, cyclohexyl styrene, decyl styrene, benzyl styrene, chloromethyl styrene, trifluoro. Dimethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, etc.), alkoxy styrene (for example, methoxy styrene, 4-methoxy-3-methyl styrene, dimethoxy styrene, etc.), halogen-containing styrene (for example, chloro styrene, dichloro styrene, trichloro styrene, Tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluoro Styrene, 2-bromo-4-trifluoromethyl styrene, 4-fluoro-3-trifluoromethyl styrene etc.).
Other specific examples include acrylonitrile and methacrylonitrile.

  The mass average molar mass (Mw) of the specific copolymer in the present invention can be arbitrarily set depending on the performance design of the lithographic printing plate precursor. From the viewpoint of printing durability and stain resistance, the weight average molar mass is preferably 2,000 to 1,000,000, more preferably 2,000 to 500,000, and 10,000 to 500,000. Most preferred is 000.

  Specific examples of the specific copolymer are shown below, but the present invention is not limited thereto. In the table, each component column represents the type of component (indicated by the number of the exemplary compound) / content in the specific copolymer (indicated by mass percentage), and (a1-2) / [(a1-1 ) + (A1-2)] represents a mass ratio. In addition, the kind of (a1-1) component and the kind of (a1-2) component were shown with the example number of the monomer structure.

The specific copolymer of the present invention is used by being contained in an undercoat layer provided between the support and the image recording layer. The content is preferably 5 to 100% by mass, more preferably 10 to 100% by mass, and most preferably 20 to 100% by mass with respect to the total mass of the undercoat layer.
Within this content range, the effect of the specific copolymer on developability, printing durability, stain resistance and aging can be obtained.

(Image recording layer)
The image recording layer used in the present invention contains (A) a polymerization initiator, (B) an infrared absorbing dye, and (C) a polymerizable compound.

<(A) Polymerization initiator>
As the polymerization initiator in the present invention, a radical polymerization initiator is preferably used. As the radical polymerization initiator, those known to those skilled in the art can be used without limitation, and specifically include, for example, trihalomethyl compounds, carbonyl compounds, organic peroxides, azo compounds, azide compounds, metallocene compounds, hexaarynes. Examples thereof include a rubiimidazole compound, an organic boron compound, a disulfone compound, an oxime ester compound, an onium salt compound, and an iron arene complex. Among these, at least one selected from the group consisting of hexaarylbiimidazole compounds, onium salts, trihalomethyl compounds, and metallocene compounds is preferable, and onium salts are particularly preferable. Two or more of the above radical polymerization initiators can be used in combination as appropriate.

  As the onium salt suitably used in the present invention, a sulfonium salt, an iodonium salt, and a diazonium salt are preferably used. In particular, diaryliodonium salts and triarylsulfonium salts are preferably used. The onium salt is particularly preferably used in combination with an infrared absorber having a maximum absorption in a wavelength range of 750 to 1400 nm.

  As other radical polymerization initiators, polymerization initiators described in paragraph numbers [0071] to [0129] of JP-A-2007-206217 can be preferably used.

The polymerization initiator in the present invention is suitably used alone or in combination of two or more.
The amount of the polymerization initiator used in the image recording layer in the present invention is preferably 0.01 to 20% by mass, more preferably 0.1 to 15% by mass, based on the total solid content of the image recording layer. More preferably, it is 1.0 mass%-10 mass%.

<(B) Infrared absorbing dye>
The infrared absorbing dye has a function of converting the absorbed infrared light into heat and a function of being excited by the infrared light and transferring electrons and / or energy to the polymerization initiator. The infrared absorbing dye used in the present invention is a dye 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.
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 preferred, and particularly preferred examples include cyanine dyes represented by the following general formula (a).

In general formula (a), X ¹ represents a hydrogen atom, a halogen atom, —N (R ⁹ ) (R ¹⁰ ), —X ² -L ¹ or a group shown below. Here, R ⁹ and R ¹⁰ may be the same or different, and may have a substituent, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, or a hydrogen atom. R ⁹ and R ¹⁰ may be bonded to each other to form a ring. Of these, a phenyl group is preferred (—NPh ₂ ). X ² represents an oxygen atom or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, a heteroaryl group, or a hydrocarbon group having 1 to 12 carbon atoms including a hetero atom. 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 each independently represent a hydrocarbon group having 1 to 12 carbon atoms. In view of storage stability of the image recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms. R ¹ and R ² may be bonded to each other to form a ring, and when forming a ring, it is particularly preferable that a 5-membered ring or a 6-membered ring is formed.

Ar ¹ and Ar ² may be the same or different and each represents an aryl group which may have a substituent. Preferred aryl 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, carboxy 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. Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (a) has an anionic substituent in its structure and neutralization of charge is not necessary. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of the storage stability of the image recording layer coating solution. , Hexafluorophosphate ions, and aryl sulfonate ions.

Specific examples of the cyanine dye represented by formula (a) that can be suitably used include compounds described in paragraphs [0017] to [0019] of JP-A No. 2001-133969, and JP-A No. 2002-023360. Paragraph numbers [0016] to [0021] of JP-A No. 2002-040638, compounds described in paragraph Nos. [0012] to [0037] of JP-A No. 2002-040638, preferably paragraph Nos. [0034] of JP-A No. 2002-278057 [0041], compounds described in paragraph numbers [0080] to [0086] of JP 2008-195018 A, most preferably compounds described in paragraph numbers [0035] to [0043] of JP 2007-90850 A Is mentioned.
Further, compounds described in paragraph numbers [0008] to [0009] of JP-A No. 5-5005 and paragraph numbers [0022] to [0025] of JP-A No. 2001-222101 can also be preferably used.

  Moreover, only 1 type may be used for these (B) infrared absorption dyes, 2 or more types may be used together, and infrared absorbers other than infrared absorption dyes, such as a pigment, may be used together. As the pigment, compounds described in JP 2008-195018 A [0072] to [0076] are preferable.

  The content of the infrared absorbing dye in the image recording layer in the present invention is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass of the total solid content of the image recording layer.

<(C) Polymerizable compound>
The radical polymerizable compound used for the image recording layer in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and has at least one, preferably two or more terminal ethylenically unsaturated bonds. Selected from compounds. These have chemical forms such as monomers, prepolymers, ie dimers, trimers and oligomers, or mixtures thereof. Examples of monomers include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof, preferably unsaturated carboxylic acids. An ester of an acid and a polyhydric alcohol compound and an amide of an unsaturated carboxylic acid and a polyvalent amine compound are used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxy group, an amino group or a 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 In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. 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. These are disclosed in JP-T-2006-508380, JP-A-2002-287344, JP-A-2008-256850, JP-A-2001-342222, JP-A-9-179296, JP-A-9-179297. JP-A-9-179298, JP-A-2004-294935, JP-A-2006-243493, JP-A-2002-275129, JP-A-2003-64130, JP-A-2003-280187, It is described in references including Kaihei 10-333321.

  Specific examples of the monomer of the ester of a polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, Examples include trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol tetraacrylate, sorbitol triacrylate, isocyanuric acid ethylene oxide (EO) -modified triacrylate, and polyester acrylate oligomer. Methacrylic acid esters include tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, pentaerythritol trimethacrylate, bis [p- (3-methacryloxy-2-hydroxypropoxy) phenyl ] Dimethylmethane, bis- [p- (methacryloxyethoxy) phenyl] dimethylmethane, and the like. Specific examples of amide monomers of polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis-methacrylic. Examples include amide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, and xylylene bismethacrylamide.

In addition, urethane-based addition-polymerizable compounds produced by using an addition reaction between an isocyanate and a hydroxy group are also suitable, and specific examples thereof include, for example, one molecule described in Japanese Patent Publication No. 48-41708. A vinyl containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxy group represented by the following general formula (b) to a polyisocyanate compound having two or more isocyanate groups. A urethane compound etc. are mentioned.
^{_{CH 2 = C (R 4)}} COOCH 2 CH (R 5) OH (b)
(However, R ⁴ and R ⁵ represent H or CH _3. )

  Also, urethanes described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-A-2003-344997, and JP-A-2006-65210. Acrylates, JP-B 58-49860, JP-B 56-17654, JP-B 62-39417, JP-B 62-39418, JP-A 2000-250211, JP-A 2007-94138 Urethane compounds having an ethylene oxide-based skeleton described in the publication, and hydrophilicity described in US Pat. No. 7,153,632, JP-A-8-505958, JP-A-2007-293221, and JP-A-2007-293223. Urethane compounds having a group are also suitable.

  Among them, tris (acryloyloxyethyl) isocyanurate, bis (acryloyloxyethyl) hydroxyethyl isocyanurate, etc. are excellent in the balance between the hydrophilicity involved in on-press developability and the polymerization ability involved in printing durability. Isocyanuric acid ethylene oxide modified acrylates are particularly preferred.

  Details of the usage method such as the structure of these polymerizable compounds, whether they are used alone or in combination, and the amount added can be arbitrarily set in accordance with the performance design of the final lithographic printing plate precursor. The polymerizable compound is preferably used in the range of 5 to 75% by mass, more preferably 10 to 70% by mass, and particularly preferably 15 to 60% by mass with respect to the total solid content of the image recording layer.

<(E) Other ingredients>
The image recording layer in the invention may further contain other components as required.

<(1) Polymer binder>
In the image recording layer of the present invention, a polymer binder can be used in order to improve the film strength of the image recording layer. As the polymer binder that can be used in the present invention, any conventionally known binder can be used without limitation, and a polymer having film properties is preferred. Of these, acrylic resins, polyvinyl acetal resins, and polyurethane resins are preferable.

  Among them, as a polymer binder suitable for the present invention, as described in JP-A-2008-195018, a crosslinkable functional group for improving the film strength of an image portion is a main chain or a side chain, preferably a side chain. Have the following. Crosslinking is formed between the polymer molecules by the crosslinkable group, and curing is accelerated.

  The crosslinkable functional group is preferably an ethylenically unsaturated group such as a (meth) acryl group, vinyl group, allyl group, or styryl group, or an epoxy group, and these groups are introduced into the polymer by polymer reaction or copolymerization. be able to. For example, a reaction between an acrylic polymer or polyurethane having a carboxy group in the side chain and polyurethane and glycidyl methacrylate, or a reaction between a polymer having an epoxy group and an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid can be used.

  The content of the crosslinkable group in the polymer binder is preferably 0.1 to 10.0 mmol, more preferably 0.25 to 7.0 mmol, and most preferably 0.5 to 5.5 mmol per 1 g of the polymer binder. .

  The polymer binder of the present invention preferably further has a hydrophilic group. The hydrophilic group contributes to imparting on-press developability to the image recording layer. In particular, the coexistence of the crosslinkable group and the hydrophilic group makes it possible to achieve both printing durability and developability.

Examples of the hydrophilic group include a hydroxy group, a carboxy group, an alkylene oxide structure, an amino group, an ammonium group, an amide group, a sulfo group, and a phosphoric acid group. Among them, an alkylene oxide unit having 2 or 3 carbon atoms Are preferably alkylene oxide structures having 1 to 120, more preferably 2 to 120. In order to impart a hydrophilic group to the polymer binder, a monomer having a hydrophilic group may be copolymerized.
These polymers may be fine particles as described in, for example, International Publication No. WO2003 / 087939, and the average particle size is preferably 30 nm to 1000 nm, more preferably 60 nm to 300 nm.

  In addition, in the polymer binder of the present invention, an oleophilic group such as an alkyl group, an aryl group, an aralkyl group, or an alkenyl group can be introduced in order to control the inking property. Specifically, a lipophilic group-containing monomer such as an alkyl methacrylate may be copolymerized.

  Specific examples (1) to (11) of the polymer binder used in the present invention are shown below, but the present invention is not limited thereto. In addition, the ratio of the repeating unit of the following polymer binder is a molar ratio.

  The polymer binder in the present invention preferably has a mass average molar mass (Mw) of 2000 or more, more preferably 5000 or more, and still more preferably 10,000 to 300,000.

  In the present invention, if necessary, hydrophilic polymers such as polyacrylic acid and polyvinyl alcohol described in JP-A-2008-195018 can be used. Further, a lipophilic polymer binder and a hydrophilic polymer binder can be used in combination.

  The content of the polymer binder 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 image recording layer. Further preferred.

(2) Hydrophobized precursor In the present invention, a hydrophobized precursor can be used to improve on-press developability. The hydrophobized precursor in the present invention means fine particles capable of converting the image recording layer to hydrophobic when heat is applied. The fine particles are at least one selected from hydrophobic thermoplastic polymer fine particles, thermally reactive polymer fine particles, polymer fine particles having a polymerizable group, microcapsules enclosing a hydrophobic compound, and microgel (crosslinked polymer fine particles). It is preferable. Among these, polymer fine particles and microgels having a polymerizable group are preferable.

Hydrophobic thermoplastic polymer fine particles include Research Disclosure No. 1 of January 1992. 331,003, JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250 and European Patent No. 931647 are suitable. Can be cited as
Specific examples of polymers constituting such polymer fine particles include ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, and polyalkylene structures. Mention may be made of homopolymers or copolymers of monomers such as acrylates or methacrylates or mixtures thereof. Among them, more preferable examples include a copolymer containing polystyrene, styrene and acrylonitrile, and polymethyl methacrylate.

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

  Examples of the heat-reactive polymer fine particles used in the present invention include polymer fine particles having a heat-reactive group, and these form a hydrophobized region by crosslinking due to a heat reaction and a functional group change at that time.

  The thermoreactive group in the polymer fine particles having a thermoreactive group used in the present invention may be any functional group that performs any reaction as long as a chemical bond is formed, but is preferably a polymerizable group, Examples include ethylenically unsaturated groups that undergo radical polymerization reactions (eg, acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, etc.), cationic polymerizable groups (eg, vinyl groups, vinyloxy groups, epoxy groups, oxetanyl groups, etc.) ), An isocyanate group that performs an addition reaction or a block thereof, an epoxy group, a vinyloxy group, and a functional group having an active hydrogen atom that is a reaction partner thereof (for example, an amino group, a hydroxy group, a carboxy group, etc.), a condensation reaction Carboxy group to be carried out and reaction partner hydroxy group or amino group, acid anhydride to carry out ring-opening addition reaction and reaction An amino group or a hydroxyl group a manual may be mentioned as suitable.

  As the microcapsules used in the present invention, for example, as described in JP-A Nos. 2001-277740 and 2001-277742, all or part of the constituent components of the image recording layer are encapsulated in the microcapsules. Is. The constituent components of the image recording layer can also be contained outside the microcapsules. Furthermore, it is preferable that the image recording layer containing the microcapsule includes a hydrophobic constituent component in the microcapsule and a hydrophilic constituent component outside the microcapsule.

  In this invention, the aspect containing a crosslinked resin particle, ie, a microgel, may be sufficient. This microgel can contain a part of the constituent components of the image recording layer in at least one of the inside and the surface thereof, and in particular, an embodiment in which a reactive microgel is formed by having a radical polymerizable group on the surface thereof, This is particularly preferable from the viewpoint of image formation sensitivity and printing durability.

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

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

  The content of the hydrophobizing precursor is preferably in the range of 5 to 90% by mass of the total solid content of the image recording layer.

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

  Among these, in the present invention, it is preferable to contain at least one selected from the group consisting of polyols, organic sulfates, organic sulfonates, and betaines.

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

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

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

  The above low molecular weight hydrophilic compound has a small hydrophobic part structure and almost no surface-active action, so that dampening water penetrates into the exposed part of the image recording layer (image part) and the hydrophobicity and film strength of the image part. Ink acceptability and printing durability of the image recording layer can be maintained satisfactorily.

The amount of these low molecular weight hydrophilic compounds added to the image recording layer is preferably 0.5% by mass or more and 20% by mass or less of the total solid content of the image recording layer. More preferably, they are 1 mass% or more and 15 mass% or less, More preferably, they are 2 mass% or more and 10 mass% or less. In this range, good on-press developability and printing durability can be obtained.
These compounds may be used alone or in combination of two or more.

(4) Grease Sensitizer In the image recording layer of the present invention, a lipid sensitizer such as a phosphonium compound, a nitrogen-containing low molecular weight compound, or an ammonium group-containing polymer is used for the image recording layer in order to improve the inking property. be able to. In particular, when an inorganic layered compound is contained in the protective layer, these compounds function as a surface coating agent for the inorganic layered compound, and prevent a decrease in the inking property during printing by the inorganic layered compound.

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

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

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

  The ammonium salt-containing polymer has a reduced specific viscosity (unit: ml / g) determined by the following measurement method, preferably in the range of 5 to 120, more preferably in the range of 10 to 110, 15 Those in the range of ~ 100 are particularly preferred. When the said reduced specific viscosity is converted into a mass average molar mass, 10,000-150,000 are preferable, 17000-140000 are more preferable, 20000-130000 are especially preferable.

<Measurement method of reduced specific viscosity>
Weigh 3.33 g of 30% polymer solution (1 g as solid content) into a 20 ml volumetric flask and make up with N-methylpyrrolidone. This solution is allowed to stand for 30 minutes in a constant temperature bath at 30 ° C., placed in an Ubbelohde reduced specific viscosity tube (viscosity constant = 0.010 cSt / s), and the time for flowing down at 30 ° C. is measured. The measurement is performed twice with the same sample, and the average value is calculated. Similarly, in the case of a blank (only N-methylpyrrolidone), the reduced specific viscosity (ml / g) was calculated from the following formula.

Specific examples of the ammonium group-containing polymer are shown below.
(1) 2- (Trimethylammonio) ethyl methacrylate = p-toluenesulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 10/90 Mw 45,000)
(2) 2- (Trimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80 Mw 60,000)
(3) 2- (Ethyldimethylammonio) ethyl methacrylate = p-toluenesulfonate / hexyl methacrylate copolymer (molar ratio 30/70 Mw 45,000)
(4) 2- (Trimethylammonio) ethyl methacrylate = hexafluorophosphate / 2-ethylhexyl methacrylate copolymer (molar ratio 20/80 Mw 60,000)
(5) 2- (Trimethylammonio) ethyl methacrylate = methyl sulfate / hexyl methacrylate copolymer (molar ratio 40/60 Mw 7 million)
(6) 2- (Butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 25/75 Mw 650,000)
(7) 2- (Butyldimethylammonio) ethyl acrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80 Mw 65,000)
(8) 2- (butyldimethylammonio) ethyl methacrylate = 13-ethyl-5,8,11-trioxa-1-heptadecanesulfonate / 3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80 Mw 75,000)
(9) 2- (butyldimethylammonio) ethyl methacrylate = hexafluorophosphate / 3,6-dioxaheptyl methacrylate / 2-hydroxy-3-methacryloyloxypropyl methacrylate copolymer (molar ratio 15/80/5 (Mw 650,000)

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

(5) Chain transfer agent The image recording layer preferably further contains a chain transfer agent. As the chain transfer agent, for example, a compound group having SH, PH, SiH, GeH in the molecule is used. These can donate hydrogen to low-activity radical species to generate radicals, or can be oxidized and then deprotonated to generate radicals.
In particular, thiol compounds (for example, 2-mercaptobenzimidazoles, 2-mercaptobenzthiazoles, 2-mercaptobenzoxazoles, 3-mercaptotriazoles, 5-mercaptotetrazoles, etc.) are linked to the image recording layer. It can be preferably used as a transfer agent.
The content of the chain transfer agent is preferably 1 to 10% by mass with respect to the total solid content of the image recording layer.

(6) Others As other components, surfactants, colorants, print-out agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic fine particles, inorganic layered compounds and the like can be added. Specifically, paragraph numbers [0114] to [0159] of Japanese Patent Application Laid-Open No. 2008-284817, paragraph numbers [0023] to [0027] of Japanese Patent Application Laid-Open No. 2006-091479, and US Patent Publication No. 2008/0311520. The compound and the addition amount described in paragraph [0060] of FIG.

(F) Formation of Image Recording Layer The image recording layer in the present invention is prepared by using the above-mentioned necessary components as known solvents as described in, for example, paragraphs [0142] to [0143] of JP-A-2008-195018. A coating solution is prepared by dispersing or dissolving in a coating solution, which is formed by applying the coating solution on a support by a known method such as bar coater coating and drying. The image recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the application, but is generally preferably 0.3 to 3.0 g / m ² . Within this range, good sensitivity and good film characteristics of the image recording layer can be obtained.

  In the image recording layer, it is preferable that at least one of the printing ink and the fountain solution is supplied on the printing press after the exposure to remove the unexposed portion, and at least the type and amount of each component in the image recording layer Such an image recording layer can be configured by appropriately adjusting one of them.

  Examples of the solvent used in the coating solution include methyl ethyl ketone, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, and γ-butyllactone. 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 image recording layer coating amount (solid content) on the support obtained after coating and drying is preferably 0.3 to 3.0 g / m ² . 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.

(Undercoat layer)
The lithographic printing plate precursor according to the invention has an undercoat layer (sometimes called an intermediate layer) between the image recording layer and the support. The undercoat layer enhances the adhesion between the support and the image recording layer in the exposed area, and easily peels off the image recording layer from the support in the unexposed area. Contributes to improvement.

  For the undercoat layer, in addition to the specific copolymer (D), a known chelating agent, secondary or tertiary amine, polymerization inhibitor, amino group, or a functional group having polymerization inhibiting ability and an aluminum support Compounds having a group that interacts with the surface (for example, 1,4-diazabicyclo [2,2,2] octane (DABCO), 2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid , Hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, and the like.

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

(Protective layer)
In the lithographic printing plate precursor according to the invention, a protective layer (overcoat layer) is preferably provided on the image recording layer. In addition to the function of suppressing the image formation inhibition reaction by blocking oxygen, the protective layer has a function of preventing scratches in the image recording layer and preventing ablation during high-illuminance laser exposure.

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

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

The protective layer is applied by a known method. 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. in the range of 02~1g / ^{m 2.}

(Support)
As the support used in the lithographic printing plate precursor according to the invention, a known support is used. Of these, an aluminum plate that has been roughened and anodized by a known method is preferred.
In addition, the above aluminum plate is optionally subjected to micropore enlargement treatment or sealing treatment of an anodized film described in JP-A Nos. 2001-253181 and 2001-322365, and US Pat. 714,066, 3,181,461, 3,280,734 and 3,902,734, or alkali metal silicates as described in U.S. Pat. Surface hydrophilization treatment with polyvinylphosphonic acid or the like as described in each specification of 3,276,868, 4,153,461 and 4,689,272 is appropriately performed and performed. be able to.
The support preferably has a center line average roughness of 0.10 to 1.2 μm.

  If necessary, the support of the present invention includes a back containing an organic polymer binder described in JP-A-5-45885 and a silicon alkoxy compound described in JP-A-6-35174. A coat layer can be provided.

[Plate making method]
A lithographic printing plate is prepared by subjecting the lithographic printing plate precursor according to the invention to image exposure and development. Development processing includes (1) a method of developing with an alkaline developer (pH is greater than 11), (2) a method of developing with a developer having a pH of 2 to 11, and (3) a dampening on a printing press. In the present invention, (3) a method of developing while adding dampening water and / or ink (machine) Top development) is most preferred.

<On-press development method>
On-press development is carried out by loading the lithographic printing plate precursor after image exposure to a printing press without performing any development processing, and then starting printing by supplying oil-based ink and an aqueous component. That is, at the initial stage of printing, the image recording layer in the unexposed area is dissolved or dispersed and removed by the oil-based ink and / or the aqueous component, and the hydrophilic support surface is exposed to form a non-image portion. . On the other hand, the image recording layer cured by exposure forms a printing ink receiving portion (image portion) having an oleophilic surface. As a result, the fountain solution adheres to the exposed hydrophilic surface, and the printing ink is deposited on the image recording layer in the exposed area, enabling normal printing.

Imagewise exposure may be performed on the printing machine after the lithographic printing plate precursor is mounted on the printing machine, or may be separately performed with a plate setter or the like. As the oil-based ink and the aqueous component, ordinary lithographic printing ink and fountain solution are used.
Here, dampening water or printing ink may be supplied to the printing plate first, but printing is first performed in order to prevent the dampening water from being contaminated by the removed image recording layer components. It is preferable to supply ink.

<Image exposure>
Prior to the above development processing, the lithographic printing plate precursor is exposed imagewise by laser exposure through a transparent original image having a line image, a halftone dot image or the like, or by laser beam scanning by digital data.
A desirable light source wavelength is preferably 750 nm to 1400 nm. As the light source of 750 nm to 1400 nm, a solid-state laser and a semiconductor laser that emit infrared rays are suitable. The exposure mechanism may be any of an internal drum system, an external drum system, a flat bed system, and the like.
Regarding the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is preferably 10 to 300 mJ / cm ² . In the laser, it is preferable to use a multi-beam laser device in order to shorten the exposure time.

  After the image exposure, it is mounted on the plate cylinder of the printing machine as it is and printing is started. In the case of a printing press equipped with a laser exposure device, image exposure is performed after a lithographic printing plate precursor is mounted on a plate cylinder of the printing press.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. In addition, in a high molecular compound, molecular weight is a mass mean molar mass (Mw), and the ratio of a repeating unit is a mole percentage except what was specially prescribed | regulated.

[Synthesis Example of Specific Copolymer 1]

[Monomer isolation example]
In a three-necked flask equipped with a stirring blade (rotation speed 250 rpm), 250 parts of diethylene glycol dibutyl ether (hereinafter abbreviated as “DBDG”), 250 parts of ion-exchanged water, and 100.0 parts of phosphate ester mixture [manufactured by Kyoeisha Chemical Co., Ltd. Light ester P-1M (containing phosphoric acid monoester and diester having the following structure. Purity of phosphoric acid monoester: 36.1% by mass) was added and stirred at room temperature for 20 minutes. The stirred liquid was transferred to a separatory funnel and allowed to stand for 10 minutes, and then the aqueous layer was taken out and transferred to a three-necked flask. DBDG (250 parts) was newly added, stirred again for 20 minutes, transferred to a separatory funnel and allowed to stand for 10 minutes, and then the aqueous layer was taken out to obtain 286.66 parts of a phosphoric acid monomer aqueous solution.
The obtained phosphoric acid monomer aqueous solution had a phosphoric diester / (phosphoric monoester + diester) mass ratio = 0.1, a concentration of 10.5% by mass, and the DBDG content in the aqueous solution was 0.3% by mass. It was.

[Synthesis of Specific Copolymer 1]
A 200 ml flask equipped with a condenser and a stirrer was charged with 142 g of distilled water and heated to 65 ° C. under a nitrogen stream. 47.6 g of the phosphoric acid monomer aqueous solution obtained above, 20.0 g of methoxypolyoxyethylene methacrylate (average EO chain length = 23), 1.137 g of polymerization initiator VA046B (manufactured by Wako Pure Chemical Industries, Ltd.), distilled water A solution consisting of 56.43 g was dropped into a 200 ml flask over 2 hours. After completion of dropping, the mixture was stirred at 65 ° C. for 2 hours, 0.057 g of a polymerization initiator VA046B (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred at 65 ° C. for 2 hours to give the specific copolymer (1). Obtained.
The obtained specific copolymer (1) had a mass average molar mass (Mw) of 50,000 as determined by gel permeation chromatography (GPC) using polyethylene glycol as a standard substance.

The other specific copolymer used in this example was synthesized by changing the monomer component of the repeating unit in the above synthesis example, and if necessary, by an existing synthesis method.
In the examples, the specific copolymer used was a compound having an Mw of about 50,000.

[Examples 1-47 and Comparative Examples 1-7]
1. Preparation of lithographic printing plate precursors 1 to 46 and comparative lithographic printing plate precursors (R-1 to R-7)

(1) Preparation of support In order to remove rolling oil on the surface of an aluminum plate (material JIS A 1050) having a thickness of 0.3 mm, degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution. After that, the aluminum surface was grained using ^three bundle-planted nylon brushes having a bristle diameter of 0.3 mm 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. At this time, the etching amount of the grained surface was about 3 g / m ² .

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

Subsequently, nitric acid electrolysis was performed with an aqueous solution of 0.5% by mass of hydrochloric acid (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. under the condition of an electric quantity of 50 C / dm ² when the aluminum plate was the anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying.
Next, a 2.5 g / m ² direct current anodic oxide film having a current density of 15 A / dm ² was provided on the plate as a 15% by weight sulfuric acid aqueous solution (containing 0.5% by weight of aluminum ions) as an electrolyte, followed by washing with water. And dried to prepare a support (1).

Thereafter, in order to ensure the hydrophilicity of the non-image area, the support (1) was subjected to a silicate treatment at 60 ° C. for 10 seconds using an aqueous 2.5 mass% No. 3 sodium silicate solution, and then washed with water for support. Body (2) was obtained. The adhesion amount of Si was 10 mg / m ² . The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

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

<Undercoat layer coating solution (1)>
-The specific copolymer listed in Table 4 or 5 or the following comparative polymer compound 0.50 g
・ Water 500.00g

(3) Formation of image recording layer The image recording layer coating solution (1) having the following composition was bar-coated on the undercoat layer formed as described above, and then oven-dried at 100 ° C for 60 seconds to obtain a dry coating amount. An image recording layer of 1.0 g / m ² was formed.
The image recording layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and microgel solution (1) immediately before coating.

<Photosensitive solution (1)>
-Binder polymer (1) [the following structure] 0.240 g
Infrared absorbing dye (1) [the following structure] 0.030 g
・ Polymerization initiator (1) [the following structure] 0.162 g
-Radical polymerizable compound Tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.192 g
・ Low molecular weight hydrophilic compound Tris (2-hydroxyethyl) isocyanurate 0.062g
・ Low molecular weight hydrophilic compound (1) [the following structure] 0.050 g
-Sensitizing agent Phosphonium compound (1) [the following structure] 0.055 g
・ Sensitizer Benzyl-dimethyl-octylammonium ・ PF ₆ salt 0.018g
-Sensitizing agent Ammonium group-containing polymer [the following structure, reduced specific viscosity 44 cSt / g / ml] 0.035 g
・ Fluorosurfactant (1) [The following structure] 0.008g
・ 2-butanone 1.091g
・ 1-methoxy-2-propanol 8.609g

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

  Binder polymer (1), infrared absorbing dye (1), polymerization initiator (1), phosphonium compound (1), low molecular weight hydrophilic compound (1), ammonium group-containing polymer, and fluorine-based surfactant ( The structure of 1) is as shown below.

-Synthesis of microgel (1)-
As the oil phase component, 4.46 g of a polyfunctional isocyanate having the following structure (made by Mitsui Chemicals Polyurethane; 75% by mass ethyl acetate solution), trimethylolpropane (6 mol) and xylene diisocyanate (18 mol) were added. 10 g of an adduct (made by Mitsui Chemicals Polyurethane; 50% by mass ethyl acetate solution) obtained by adding polyoxyethylene (one mole, 90 repeats of oxyethylene units) to one-sided, pentaerythritol triacrylate (Nippon Kayaku) 3.15 g of SR444 manufactured by Co., Ltd. and 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) were dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of polyvinyl alcohol (PVA-205 manufactured by Kuraray Co., Ltd.) was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12,000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 50 ° C. for 3 hours. The microgel solution thus obtained was diluted with distilled water to a solid content concentration of 15% by mass, and this was designated as the microgel (1). When the average particle size of the microgel was measured by a light scattering method, the average particle size was 0.2 μm.

(4) Formation of protective layer After the bar coating of the protective layer coating solution (1) having the following composition was further applied on the image recording layer, it was oven-dried at 120 ° C. for 60 seconds, and the dry coating amount was 0.15 g / m ² And a planographic printing plate precursor (1) to (46) [for Examples 1 to 46], and a planographic printing plate precursor (R-1) to (R-7) [for Comparative Examples 1 to 7] ] Was obtained.

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

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

2. Preparation of lithographic printing plate precursor 47 In the synthesis of specific copolymer 1, 2-acrylamido-2-methylpropanesulfonic acid (manufactured by MRC Unitech Co., Ltd.) instead of methoxypolyoxyethylene methacrylate (average EO chain length = 23) Was used to obtain the specific copolymer 47.
A lithographic printing plate precursor 47 (for Example 47) was produced in the same manner as in the production of the lithographic printing plate precursor 1, except that this specific copolymer 47 was used.

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

<Print durability>
Printing was continued after the on-press developability described above. As the number of printed sheets was increased, the image recording layer was gradually worn out, so that the ink density on the printed material decreased. Printing durability was evaluated using the number of printed copies when the value measured by the Gretag densitometer for the 50% halftone dot area ratio of the FM screen in the printed material was 5% lower than the measured value for the 100th printed sheet. . The larger the number of finished sheets, the higher the printing durability.

<Stain resistance after aging>
A lithographic printing plate precursor left in a constant temperature and humidity chamber set at 60 ° C. and a relative humidity of 70% for 4 days is printed by the above method, and after completion of on-press development, the 20th printed matter is extracted and adhered to the non-image area The stain resistance was evaluated based on the ink density. A score of 10 out of 10 was assigned by visual evaluation. The higher the score, the better the stain resistance. Since the ink adhesion in the non-image area does not always occur uniformly, the evaluation of stain resistance was taken as the visual evaluation score.

[Examples 51-58 and Comparative Examples 11-14]
After providing an undercoat layer having the specific copolymer described in Table 6 in the same manner as in Example 1, the following image recording layer coating solution (2) was bar-coated, then oven-dried at 70 ° C. for 60 seconds, and dried. An image recording layer having a coating amount of 0.6 g / m ² was prepared, and lithographic printing plate precursors (51) to (58) and lithographic printing plate precursors (R-11) to (R-14) were obtained. Got.

<Image recording layer coating solution (2)>
-Polymer fine particle aqueous dispersion (1) 20.0 g
・ Infrared absorbing dye (2) [The following structure] 0.2g
-Radical generator Irgacure250 (Ciba Specialty Chemicals) 0.5g
・ Radically polymerizable compound SR-399 (Sartomer) 1.50 g
・ Mercapto-3-triazole 0.2g
・ Byk336 (Byk Chimie) 0.4g
・ KlucelM (Hercules) 4.8g
・ ELVACITE4026 (Ineos Acrylica) 2.5g
・ N-propanol 55.0g
・ 2-butanone 17.0g

In addition, the compounds described by trade names in the above composition are as follows.
IRGACURE 250: (4-methoxyphenyl) [4- (2-methylpropyl) phenyl] iodonium = hexafluorophosphate (75% by mass propylene carbonate solution)
・ SR-399: Dipentaerythritol pentaacrylate
BYK 336: modified dimethylpolysiloxane copolymer (25% by mass xylene / methoxypropyl acetate solution)
・ KLUCEL M: Hydroxypropyl cellulose (2 mass% aqueous solution)
ELVACITE 4026: Hyperbranched polymethyl methacrylate (10% by mass 2-butanone solution)

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

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

  The resulting lithographic printing plate precursors (51) to (58) and (R-11) to (R-14) were evaluated in the same manner as in Examples 1 to 47. The results are shown in Table 6 below.

Claims (6)

A lithographic plate having an image recording layer containing (A) a polymerization initiator, (B) an infrared-absorbing dye, and (C) a polymerizable compound, which can be removed by at least one of printing ink and fountain solution on a support. In the printing plate precursor, an undercoat layer provided between the support and the image recording layer is (D) a repeating unit derived from a monomer represented by the following general formula (a1-1), the following general formula ( a repeating unit derived from the monomer represented by a1-2) and a repeating unit derived from the monomer represented by the general formula (a1-1), including a repeating unit having a hydrophilic group in the side chain, and a general formula ( The mass ratio of the repeating unit derived from the monomer represented by the general formula (a1-2) to the sum of the mass of the repeating unit derived from the monomer represented by a1-2) is 0.03 to 0.25. Characterized by containing a copolymer The lithographic printing plate precursor that.
Formula _{(a1-1) CH 2 = C (} R 1) COO (R 2 O) n P = O (OH) 2
Formula _{(a1-2) [CH 2 = C} (R 1) COO (R 2 O) n] 2 P = O (OH)
Wherein, R ₁ is each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ₂ each independently represent a branched alkylene group which may number 2-3 carbon, n represents each independently The integer of 1-10 is represented.   The repeating unit having a hydrophilic group in the side chain contained in the copolymer is (a2) a repeating unit containing an oxyalkylene structure in the side chain, and (a3) a repeating unit containing a zwitterionic structure in the side chain. The lithographic printing plate precursor as claimed in claim 1, wherein the lithographic printing plate precursor is at least one repeating unit selected from the group consisting of:   The lithographic printing plate precursor as claimed in claim 1 or 2, wherein the copolymer further comprises (a4) a repeating unit containing an ethylenically unsaturated bond in a side chain.   In the copolymer, a general formula (for a sum of masses of a repeating unit derived from the monomer represented by the general formula (a1-1) and a repeating unit derived from the monomer represented by the general formula (a1-2) ( The lithographic printing plate according to any one of claims 1 to 3, wherein the mass ratio of the repeating units derived from the monomer represented by a1-2) is from 0.03 to 0.10. Original edition.   In the copolymer, the sum of the mass of the repeating unit derived from the monomer represented by the general formula (a1-1) and the repeating unit derived from the monomer represented by the general formula (a1-2) is The lithographic printing plate precursor as claimed in any one of claims 1 to 4, wherein the mass ratio of the total repeating units constituting the coal to the total mass is 0.01 or more and 0.8 or less.   After the lithographic printing plate precursor according to any one of claims 1 to 5 is image-wise exposed, at least one of printing ink and fountain solution is supplied on a printing machine to form an unexposed portion of the image recording layer. A method for making a lithographic printing plate, comprising removing the lithographic printing plate.