JP4909532B2 - Planographic printing plate making method - Google Patents

Description

  The present invention relates to a lithographic printing plate making method and a lithographic printing method. More specifically, the present invention relates to a plate-making method of a negative lithographic printing plate in which an unexposed portion of an image recording layer is removed using an aqueous solution after exposure, and a lithographic printing method having improved on-press developability and ink setting properties.

In general, a lithographic printing plate has a surface composed of an oleophilic image portion and a hydrophilic non-image portion. In lithographic printing, dampening water and oil-based ink are alternately applied to the plate surface, and the hydrophilic non-image area is dampened with a dampening water receiving area (ink non-receiving area) by utilizing the property that water and oil repel each other. ), After the ink is received only in the oleophilic 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 has been widely used. Usually, after exposing the lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer to be an image portion is left, and the other unnecessary image recording layer is removed with an alkaline developer or an organic solvent. The lithographic printing plate is obtained by carrying out plate making by a method in which the surface of the hydrophilic support is exposed by dissolving and removing to form a non-image portion.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing unnecessary image recording layers with a developer or the like is necessary after exposure, but simplifies such additional wet processing. This is one of the issues. As one of simplification, it is desired that development can be performed with an aqueous solution close to neutrality or simple water.

  On the other hand, in recent years, digitization technology that electronically processes, stores, and outputs image information using a computer has become widespread, and various new image output methods corresponding to such digitization technology have been put into practical use. It has come to be. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate technology for manufacturing is attracting attention. Accordingly, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.

  From the background as described above, it is now more strongly desired than ever to adapt both the simplification of the plate making operation and the digitization.

  On the other hand, for example, in Patent Document 1, in an image forming layer of a lithographic printing plate precursor having an image forming layer containing a hydrophobizing precursor, a hydrophilic resin, and a photothermal conversion agent on a hydrophilic support. Furthermore, by containing a compound having an ethylene oxide chain, in addition to on-press development, it can be used for printing after exposure and after liquid development processing using water or a suitable aqueous solution as a developer. Is described.

  Patent Document 2 contains (i) a hydrophilic support, and (ii) a radical polymerizable ethylenically unsaturated monomer, a radical polymerization initiator and an infrared absorbing dye, and is cured by infrared laser exposure. Moreover, a lithographic printing plate precursor comprising an oleophilic heat-sensitive layer containing 60% by mass or more of water and developable with an aqueous developer having a pH of 2.0 to 10.0 is prepared and exposed imagewise with an infrared laser. A processing method for a lithographic printing plate precursor comprising removing an uncured region of the heat-sensitive layer with an aqueous developer is described. However, the above technique still has insufficient developability or printing durability.

As another simple plate-making method, an image recording layer that can remove unnecessary portions of the image recording layer in a normal printing process is used. After exposure, unnecessary portions of the image recording layer are removed on a printing press. A method called on-press development for obtaining a lithographic printing plate has been proposed.
As a specific method of on-press development, for example, a method of using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in dampening water, an ink solvent, or an emulsion of dampening water and ink , A method of mechanically removing the image recording layer by contact with rollers or a blanket of a printing press, cohesion of the image recording layer or adhesion between the image recording layer and the support by penetration of dampening water, ink solvent, etc. There is a method in which after the force is weakened, the image recording layer is mechanically removed by contact with rollers or a blanket.

For example, Patent Document 3 describes a lithographic printing plate precursor in which an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is provided on a hydrophilic support. This lithographic printing plate precursor is formed by image exposure using an infrared laser to form an image by coalescence of hydrophobic thermoplastic polymer particles by heat, and is then mounted on a cylinder of a printing machine, fountain solution and / or On-press development is possible with ink.
However, the method of forming an image by merging the fine particles by simple thermal fusion shows good on-press developability, but the image strength (adhesion with the support) is extremely weak and the printing durability is poor. Had the problem of being sufficient.

Patent Documents 4 and 5 describe lithographic printing plate precursors comprising microcapsules encapsulating a polymerizable compound on a hydrophilic support. Further, Patent Document 6 describes a lithographic printing plate precursor in which a photosensitive layer containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on a support. These methods using a polymerization reaction have a feature that the image strength is relatively good because the chemical bond density of the image portion is higher than that of the image portion formed by thermal fusion of polymer fine particles. However, the on-press development type lithographic printing plate precursor improved the printing durability by utilizing the polymerization reaction, but on-press developability was still insufficient from a practical viewpoint. Further, in order to enable on-press development, it is essential that the image recording layer contains a hydrophilic component. Therefore, the on-press development type lithographic printing plate precursor has a problem of poor ink deposition. there were.
JP 2002-365789 A US Patent Application Publication No. 2004/0013968 Japanese Patent No. 2938397 JP 2001-277740 A JP 2001-277742 A JP 2002-287334 A

  The present invention solves the above problems. That is, an object of the present invention is to provide a plate-making method of a negative lithographic printing plate that is developed using a specific aqueous solution that has both good developability and printing durability. Another object of the present invention is to provide a method excellent in developability and ink deposition in a lithographic printing method of a lithographic printing plate precursor including on-press development.

＜２＞ 前記重合開始剤が、オニウム塩（但し、有機ホウ素塩化合物を除く）であるこ
とを特徴とする上記＜１＞に記載の平版印刷版の製版方法。
＜３＞ 前記重合開始剤が、下記一般式（ＲＩ−Ｉ）〜（ＲＩ−ＩＩＩ）のいずれかで
表されるオニウム塩（但し、有機ホウ素塩化合物を除く）であることを特徴とする上記＜
２＞に記載の平版印刷版の製版方法。

式（ＲＩ−Ｉ）中、Ａｒ₁₁は置換基を１〜６個有していてもよい炭素数２０以下のアリ
ール基を表す。Ｚ₁₁ ⁻は１価の陰イオンを表す。
式(ＲＩ−ＩＩ)中、Ａｒ₂₁およびＡｒ₂₂は、各々独立に置換基を１〜６個有していても
よい炭素数２０以下のアリール基を表す。Ｚ₂₁ ⁻は１価の陰イオンを表す。
式（ＲＩ−ＩＩＩ）中、Ｒ₃₁、Ｒ₃₂およびＲ₃₃は、各々独立に置換基を１〜６個有して
いてもよい炭素数２０以下のアリール基、アルキル基、アルケニル基、またはアルキニル
基を表す。Ｚ₃₁ ⁻は１価の陰イオンを表す。
＜４＞ 前記平版印刷版原版が分子内に支持体密着性基と重合性基とを有する化合物を
含有する下塗り層を有することを特徴とする上記＜１＞〜＜３＞のいずれか一項に記載の
平版印刷版の製版方法。
＜５＞ 画像記録層にマイクロカプセルを含有することを特徴とする上記＜１＞〜＜４
＞のいずれか一項に記載の平版印刷版の製版方法。
＜６＞ 画像記録層が紫外感光性であることを特徴とする上記＜１＞〜＜５＞のいずれ
か一項に記載の平版印刷版の製版方法。
＜７＞ 画像記録層が赤外感光性であることを特徴とする上記＜１＞〜＜５＞のいずれ
か一項に記載の平版印刷版の製版方法。
＜８＞ 前記画像様露光を７６０〜１２００ｎｍの範囲のいずれかの波長の光を放射す
るレーザーを用いて行うことを特徴とする上記＜１＞〜＜５＞のいずれか一項に記載の平
版印刷版の製版方法。
＜９＞ 前記画像様露光を２５０〜４２０ｎｍの範囲のいずれかの波長の光を放射する
レーザーを用いて行うことを特徴とする上記＜１＞〜＜５＞のいずれか一項に記載の平版
印刷版の製版方法。
＜１０＞ 前記の親水性支持体が、陽極酸化後、封孔処理されてなる支持体であること
を特徴とする
上記＜１＞〜＜９＞のいずれか一項に記載の平版印刷版の製版方法。
本発明は、上記＜１＞〜＜１０＞に係る発明であるが、以下、他の事項も含めて記載し
ている。
１．親水性支持体上に非水溶性高分子を含有するネガ型画像記録層を有する平版印刷版
原版を、画像様露光後、水溶液を用いて未露光部の画像記録層を除去する平版印刷版の製
版方法において、該水溶液の液温度が該非水溶性高分子のガラス転移温度（Ｔｇ）よりも
高いことを特徴とする平版印刷版の製版方法。
２．前記平版印刷版原版が分子内に支持体密着性基と重合性基とを有する化合物を含有
する下塗り層を有することを特徴とする前記１記載の平版印刷版の製版方法。
３．画像記録層にマイクロカプセルを含有することを特徴とする前記１または２に記載
の平版印刷版の製版方法。
４．画像記録層が紫外感光性であることを特徴とする前記１〜３のいずれかに記載の平
版印刷版の製版方法。
５．画像記録層が赤外感光性であることを特徴とする前記１〜３のいずれかに記載の平
版印刷版の製版方法。
６．前記画像様露光を７６０〜１２００ｎｍの範囲のいずれかの波長の光を放射するレ
ーザーを用いて行うことを特徴とする前記１〜３のいずれかに記載の平版印刷版の製版方
法。
７．前記画像様露光を２５０〜４２０ｎｍの範囲のいずれかの波長の光を放射するレー
ザーを用いて行うことを特徴とする前記１〜３のいずれかに記載の平版印刷版の製版方法
。
８．前記の親水性支持体が、陽極酸化後、封孔処理されてなる支持体であることを特徴
とする前記１〜７のいずれかに記載の平版印刷版の製版方法または平版印刷方法。
９．支持体上に、印刷インキ、湿し水またはこれらの両方により除去可能な画像記録層
を有する平版印刷版原版を、画像様露光により露光部の画像記録層を硬化させた後、疎水
性有機化合物および水溶性高分子化合物を含む水溶液に接触させてから、印刷インキと湿
し水とを供給して印刷を行うことを特徴とする平版印刷方法。
１０．画像記録層が、（１）重合開始剤および（２）重合性化合物を含有することを特
徴とする前記９記載の平版印刷方法。
１１．画像記録層にマイクロカプセルを含有することを特徴とする前記９または１０に
記載の平版印刷方法。
１２．画像記録層が紫外感光性であることを特徴とする前記９〜１１のいずれかに記載
の平版印刷方法。
１３．画像記録層が赤外感光性であることを特徴とする前記９〜１１のいずれかに記載
の平版印刷方法。
１４．前記画像様露光を７６０〜１２００ｎｍの範囲のいずれかの波長の光を放射する
レーザーを用いて行うことを特徴とする前記９〜１１のいずれかに記載の平版印刷方法。
１５．前記画像様露光を２５０〜４２０ｎｍの範囲のいずれかの波長の光を放射するレ
ーザーを用いて行うことを特徴とする前記９〜１１のいずれかに記載の平版印刷方法。 <1> Negative type containing a water-insoluble polymer (excluding the following polymers A to C) , a polymerization initiator (excluding organic boron salt compounds) and a polymerizable compound on a hydrophilic support. In a lithographic printing plate making method in which a lithographic printing plate precursor having an image recording layer is imagewise exposed and then the image recording layer in an unexposed part is removed using an aqueous solution, the liquid temperature of the aqueous solution is that of the water-insoluble polymer. A plate making method of a lithographic printing plate characterized by being higher than a glass transition temperature (Tg).
Each of the polymers A to C is a polymer composed of the repeating units shown below.

<2> The method for making a lithographic printing plate as described in <1> above, wherein the polymerization initiator is an onium salt (excluding an organic boron salt compound).
<3> The above-mentioned polymerization initiator is an onium salt represented by any one of the following general formulas (RI-I) to (RI-III) (excluding an organic boron salt compound) <
2. A process for making a lithographic printing plate as described in 2>.

In formula (RI-I), Ar ₁₁ represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents. Z ₁₁ ^- represents a monovalent anion.
In formula (RI-II), Ar ₂₁ and Ar ₂₂ each independently represent an aryl group having 20 or less carbon atoms, which may have 1 to 6 substituents. Z ₂₁ ^- represents a monovalent anion.
In the formula (RI-III), R ₃₁ , R ₃₂ and R ₃₃ are each independently an aryl group, alkyl group, alkenyl group or alkynyl having 20 or less carbon atoms, which may have 1 to 6 substituents. Represents a group. Z ₃₁ ^- represents a monovalent anion.
<4> The lithographic printing plate precursor as described in any one of <1> to <3>, wherein the lithographic printing plate precursor has an undercoat layer containing a compound having a support adhesion group and a polymerizable group in the molecule. A process for making a lithographic printing plate as described in 1.
<5> The above <1> to <4, wherein the image recording layer contains microcapsules.
> The plate-making method of the lithographic printing plate as described in any one of>.
<6> The method for making a lithographic printing plate as described in any one of <1> to <5> above, wherein the image recording layer is ultraviolet-sensitive.
<7> The plate making method of a lithographic printing plate as described in any one of <1> to <5> above, wherein the image recording layer is infrared-sensitive.
<8> The lithographic plate according to any one of <1> to <5>, wherein the imagewise exposure is performed using a laser that emits light having a wavelength in the range of 760 to 1200 nm. How to make a printing plate.
<9> The lithographic plate according to any one of <1> to <5>, wherein the imagewise exposure is performed using a laser that emits light of any wavelength in the range of 250 to 420 nm. How to make a printing plate.
<10> The lithographic printing plate as described in any one of <1> to <9> above, wherein the hydrophilic support is a support formed by an anodizing and then a sealing treatment Plate making method.
Although this invention is invention which concerns on said <1>-<10>, below, other matters are also described.
1. A lithographic printing plate precursor having a negative image-recording layer containing a water-insoluble polymer on a hydrophilic support is subjected to imagewise exposure, and the image-recording layer in an unexposed area is removed using an aqueous solution. In the plate making method, a lithographic printing plate making method, wherein the temperature of the aqueous solution is higher than the glass transition temperature (Tg) of the water-insoluble polymer.
2. 2. The method for making a lithographic printing plate as described in 1 above, wherein the lithographic printing plate precursor has an undercoat layer containing a compound having a support adhesion group and a polymerizable group in the molecule.
3. 3. The plate making method of a lithographic printing plate as described in 1 or 2 above, wherein the image recording layer contains microcapsules.
4). 4. The plate making method of a lithographic printing plate as described in any one of 1 to 3 above, wherein the image recording layer is ultraviolet-sensitive.
5. 4. The method for making a lithographic printing plate as described in any one of 1 to 3 above, wherein the image recording layer is infrared-sensitive.
6). 4. The plate making method of a lithographic printing plate as described in any one of 1 to 3 above, wherein the imagewise exposure is performed using a laser that emits light of any wavelength in the range of 760 to 1200 nm.
7). 4. The plate making method of a lithographic printing plate as described in any one of 1 to 3 above, wherein the imagewise exposure is performed using a laser that emits light of any wavelength in the range of 250 to 420 nm.
8). The lithographic printing plate making method or lithographic printing method according to any one of 1 to 7, wherein the hydrophilic support is a support formed by an anodizing and then a sealing treatment.
9. A lithographic printing plate precursor having an image recording layer that can be removed by printing ink, fountain solution or both on the support, and the image recording layer of the exposed portion is cured by imagewise exposure, and then a hydrophobic organic compound And a lithographic printing method comprising printing after contacting with an aqueous solution containing a water-soluble polymer compound and supplying printing ink and fountain solution.
10. 10. The lithographic printing method as described in 9 above, wherein the image recording layer comprises (1) a polymerization initiator and (2) a polymerizable compound.
11. 11. The lithographic printing method as described in 9 or 10 above, wherein the image recording layer contains microcapsules.
12 The lithographic printing method as described in any one of 9 to 11, wherein the image recording layer is ultraviolet-sensitive.
13. The lithographic printing method as described in any one of 9 to 11, wherein the image recording layer is infrared-sensitive.
14 The lithographic printing method according to any one of 9 to 11, wherein the imagewise exposure is performed using a laser that emits light of any wavelength in the range of 760 to 1200 nm.
15. The lithographic printing method according to any one of 9 to 11, wherein the imagewise exposure is performed using a laser that emits light of any wavelength in the range of 250 to 420 nm.

  Although the working mechanism of the present invention is not necessarily clear, in the plate making method, the water-insoluble polymer in the unexposed portion of the image recording layer is softened by being heated to a temperature higher than Tg in the liquid. It is presumed that water easily penetrates into the layer, and as a result, developability is greatly improved. Further, in the lithographic printing method of the present invention, after exposing the lithographic printing plate precursor to an aqueous solution containing a hydrophobic organic compound and a water-soluble polymer compound after image exposure, the hydrophobic organic compound is applied to the image portion cured by exposure. Ink adhesion is improved by adsorbing the surface of the ink and the ink adhesion is improved. In addition, the hydrophobic organic compound penetrates the unexposed and uncured image recording layer. It is presumed that developability is improved by penetration.

  ADVANTAGE OF THE INVENTION According to this invention, the plate-making method of the negative type lithographic printing plate developed using aqueous solution with favorable developability and printing durability can be provided. Moreover, according to this invention, the lithographic printing method excellent in developability and ink deposit property can be provided.

[Plate making method]
In the plate-making method of the present invention, after imagewise exposure, when the unexposed portion of the image recording layer of the lithographic printing plate precursor is removed using an aqueous solution, the liquid temperature of the aqueous solution is the water-insoluble solution used for the negative image recording layer. It is characterized by being higher than the glass transition temperature (Tg) of the conductive polymer.

In the present invention, the aqueous solution used after exposure can be used without particular limitation as long as it is a liquid containing water as a main component, but is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 97% by mass. An aqueous solution containing the above water, including water. The aqueous solution can preferably contain less than 10% by weight, more preferably less than 5% by weight of additives such as organic solvents, surfactants and other additives. The additive is more preferably 3% by mass or less, and still more preferably 1% by mass or less. The pH of the aqueous solution is preferably 2 to 10, more preferably 3 to 9, and further preferably 4 to 8.
By combining such an aqueous solution with little water or additives and close to water and a liquid temperature higher than the glass transition temperature (Tg) of the water-insoluble polymer used in the image recording layer, good developability and printing durability Can be achieved.

  As the organic solvent, a water-soluble organic solvent is preferable, and alcohols are particularly preferable. Examples of alcohols include water-soluble alkyl alcohols, aralkyl alcohols, alkoxyalkyl alcohols, allyl alkoxyalkyl alcohols, alloxyalkyl alcohols, oxydialkanols, and alkyl lactates. The alkyl group or aryl group of these alcohols may have other functional groups such as an ester group, an ether group, an epoxy group, and an ethylene group. Specific examples of useful alcohols include benzyl alcohol, phenethyl alcohol, isopropyl alcohol, n-propyl alcohol, ethyl alcohol, butyl alcohol, ethyl lactate, propyl lactate, butyl lactate, methoxyethanol, ethoxyethanol, propoxyethanol, butoxyethanol, methoxy Examples include propanol, propoxypropanol, butoxypropanol, diethylene glycol, phenoxyethanol, and phenoxypropanol. Two or more of these alcohols can be used in combination.

  Examples of the surfactant include ionic and nonionic water-soluble surfactants. Examples of useful surfactants include polyethylene glycol, polypropylene glycol, copolymers of ethylene glycol and propylene glycol, polysiloxane surfactants, ionic or nonionic perfluorosurfactants, dioctyl sodium sulfosuccinate, dodecylbenzene Examples include sodium sulfonate, sodium dibutylnaphthalene sulfonate, and ammonium lauryl sulfate.

  Other additives include antifoams, preservatives, water softeners, organic or inorganic salts (e.g. sodium citrate, sodium salicylate, sodium caprylate, sodium toluenesulfonate, sodium xylenesulfonate, potassium phosphate, And sodium sulfite).

  The aqueous solution used after exposure in the present invention is used at a liquid temperature higher than the glass transition temperature of the water-insoluble polymer used in the image recording layer of the lithographic printing plate precursor. The liquid temperature is not particularly limited as long as it is higher than the glass transition temperature Tg of the water-insoluble polymer, but it is preferably 5 ° C. higher than Tg. Moreover, although preferable liquid temperature is dependent on the glass transition temperature of the water-insoluble polymer used, Preferably it is 25-90 degreeC. Here, the liquid temperature means the temperature of the aqueous solution in the part in contact with the lithographic printing plate precursor.

  Examples of the method for removing, that is, developing the image recording layer unexposed portion of the lithographic printing plate precursor using the aqueous solution of the present invention include hand development, immersion development, and processing with an automatic developing machine.

  In the case of manual development, a sponge or absorbent cotton is sufficiently mixed with an aqueous solution, developed while rubbing the entire plate surface, and thoroughly washed with water after completion of development. In the case of immersion development, the lithographic printing plate precursor is immersed in a vat or deep tank containing an aqueous solution for about 60 seconds and stirred, and then sufficiently washed with water while rubbing with absorbent cotton or sponge.

  As an automatic processor, an automatic processor conventionally known for PS plates and CTP plates can be used. For example, a method in which the developer in the developer tank is pumped up and sprayed from a spray nozzle to develop, a method in which the printing plate is immersed and conveyed in the developer tank filled with the developer by a submerged guide roll, and the like, Any method of a so-called disposable processing method in which a substantially unused developer is supplied and processed for each plate as needed is applicable. In any system, those having a rubbing mechanism with a brush or a molton are more preferable. In addition, an apparatus in which a laser exposure unit and an automatic processor unit are integrated can be used.

  After completion of development with the aqueous solution of the present invention, the lithographic printing plate is washed with water and gummed. When the aqueous solution of the present invention is water, it can be gummed without washing. As the gum, those known for conventional PS plates can be used. Further, post-processing such as burning and erasing can be performed in the same manner as the conventional PS plate.

Prior to the above development processing, the lithographic printing plate precursor is exposed through a transparent original image having a line image, a halftone dot image or the like, or imagewise exposed by laser beam scanning or the like using digital data. Examples of light sources suitable for exposure include carbon arc lamps, mercury lamps, xeno lamps, metal hydrado lamps, strobes, ultraviolet rays, infrared rays, and laser beams. A laser beam is particularly preferable, and examples thereof include a solid-state laser and a semiconductor laser that emit infrared light of 760 to 1200 nm, an ultraviolet semiconductor laser that emits light of 250 to 420 nm, an argon ion laser that emits visible light, and an FD-YAG laser. Among these, from the viewpoint of simplification of plate making, a laser that emits infrared rays or ultraviolet rays that can be operated under white light or yellow light is preferable.

[Lithographic printing method]
In the lithographic printing method of the present invention, a lithographic printing plate precursor is contacted with an aqueous solution containing a hydrophobic organic compound and a water-soluble polymer compound after imagewise exposure, and then printing is performed by supplying printing ink and fountain solution. It is characterized by performing. Hereinafter, this aqueous solution is also referred to as a treatment liquid.

  The hydrophobic organic compound used in the treatment liquid of the present invention refers to a compound having a solubility in water of 10% by mass or less at room temperature (20 ° C.). These compounds have the property of penetrating into the unexposed image recording layer. Examples of such hydrophobic organic compounds include the following. However, it is not limited to these.

  For example, carboxylic acid esters such as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol monobutyl acetate, butyl lactate, butyl levulinate; ketones such as ethyl butyl ketone, methyl isobutyl ketone, cyclohexanone; Alcohols such as ethylene glycol monobutyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenyl carbinol, n-amyl alcohol, methyl amyl alcohol; alkyl-substituted aromatic hydrocarbons such as xylene; Halogenated hydrocarbons such as methylene dichloride, ethylene dichloride, monochlorobenzene; N-phenylethanolamine, N-phenyldiethanolamine There is such as amines such as emissions. These hydrophobic compounds may be used alone or in combination of two or more. Among these, ethylene glycol monophenyl ether, benzyl alcohol, N-phenylethanolamine and N-phenyldiethanolamine are particularly effective.

  The content of the hydrophobic organic compound in the treatment liquid is generally 0.1 to 10% by mass, particularly preferably 0.5 to 5% by mass.

  Examples of the water-soluble polymer compound used in the treatment agent of the present invention include soybean polysaccharide, modified starch, gum arabic, dextrin, fiber derivatives (eg, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.) and modified products thereof, pullulan, polyvinyl Examples include alcohols and derivatives thereof, polyvinylpyrrolidone, polyacrylamide and acrylamide copolymers, vinyl methyl ether / maleic anhydride copolymers, vinyl acetate / maleic anhydride copolymers, styrene / maleic anhydride copolymers, and the like.

  As the soybean polysaccharide, those conventionally known can be used. For example, as a commercial product, there is a trade name Soya Five (manufactured by Fuji Oil Co., Ltd.), and various grades can be used. What can be preferably used is one in which the viscosity of a 10% by mass aqueous solution is in the range of 10 to 100 mPa / sec.

  As said modified starch, what is shown by general formula (I) is preferable. As the starch represented by the general formula (I), any starch such as corn, potato, tapioca, rice and wheat can be used. These starch modifications can be made by a method of decomposing in the range of 5 to 30 glucose residues per molecule with an acid or an enzyme, and further adding oxypropylene in an alkali.

  (In the formula, the degree of etherification (degree of substitution) is in the range of 0.05 to 1.2 per glucose unit, n represents an integer of 3 to 30, and m represents an integer of 1 to 3.)

  Among the water-soluble polymer compounds, soybean polysaccharides, modified starch, gum arabic, dextrin, carboxymethyl cellulose, polyvinyl alcohol and the like are particularly preferable.

  Two or more water-soluble polymer compounds can be used in combination. The content of the water-soluble polymer compound in the treatment liquid is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass.

  In addition to the above, the treatment liquid of the present invention may contain a surfactant, a wetting agent, a preservative, a chelate compound, an antifoaming agent, an organic acid, an inorganic acid, an inorganic salt, and the like.

Examples of the surfactant include an anionic surfactant and / or a nonionic surfactant. Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonic acid salts, alkane sulfonic acid salts, dialkyl sulfosuccinic acid salts,
Linear alkylbenzene sulfonates, branched alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkylsulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated castor oil, sulfated beef tallow oil, sulfate esters of fatty acid alkyl esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfate esters, fatty acid monoglyceride sulfate Ester salts, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene styrylphenyl ether sulfates, alkyl phosphates Salt, polyoxyethylene alkyl ether phosphate ester salt, polyoxyethylene alkyl phenyl ether phosphate ester salt, partially saponified styrene-maleic anhydride copolymer, partially saponified olefin-maleic anhydride copolymer, And naphthalene sulfonate formalin condensates. Among these, dialkyl sulfosuccinates, alkyl sulfate esters and alkyl naphthalene sulfonates are particularly preferably used.

  Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ether, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid moieties. Esters, propylene glycol monofatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylene glycerin Fatty acid partial esters, polyoxyethylene diglycerins, fatty acid diethanolamides, N, N-bis-2-hydroxyalkyl Min, polyoxyethylene alkylamine, triethanolamine fatty acid esters, such as trialkylamine oxides. Of these, polyoxyethylene alkylphenyl ethers, polyoxyethylene-polyoxypropylene block copolymers and the like are preferably used. Acetylene glycol-based and acetylene alcohol-based oxyethylene adducts, fluorine-based, silicon-based anions, and nonionic surfactants can also be used in the same manner. Two or more of these surfactants can be used in combination. For example, a combination of two or more different anionic surfactants or a combination of an anionic surfactant and a nonionic surfactant is preferable. These compounds are preferably selected and used in consideration of environmental effects. The amount of the surfactant used is not particularly limited, but is preferably 0.01 to 20% by mass based on the total mass of the treatment liquid.

  As the wetting agent, ethylene glycol, propylene glycol, triethylene glycol, butylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, diglycerin and the like are preferably used. These wetting agents may be used alone or in combination of two or more. Generally, the wetting agent is used in an amount of 0.1 to 5% by weight based on the total weight of the treatment liquid.

Preservatives include phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benzisothiazolin-3-one, benztriazole derivatives, amiding anidine derivatives, quaternary ammonium salts, pyridine, Derivatives such as quinoline and guanidine, diazine, triazole derivatives, oxazole, oxazine derivatives, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3diol, 1,1-dibromo-1-nitro-2-ethanol, 1,1-dibromo-1-nitro-2-propanol and the like can be preferably used. The preferred addition amount is an amount that exerts a stable effect on bacteria, molds, yeasts, etc., and varies depending on the types of bacteria, molds, yeasts, but is 0.01- The range of 4% by mass is preferable, and it is preferable to use two or more kinds of preservatives together so as to be effective against various molds and sterilization.

  Examples of the chelate compound include ethylenediaminetetraacetic acid, potassium salt thereof, sodium salt thereof; diethylenetriaminepentaacetic acid, potassium salt thereof, sodium salt thereof; triethylenetetraminehexaacetic acid, potassium salt thereof, sodium salt thereof, hydroxyethylethylenediaminetriacetic acid Nitrilotriacetic acid, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri (methylenephosphonic acid), potassium salt, sodium salt And organic phosphonic acids and phosphonoalkanetricarboxylic acids. Organic amine salts are also effective in place of the sodium and potassium salts of the chelating agents. These chelating agents are selected so that they exist stably in the treatment liquid composition and do not impair the printability. The addition amount is suitably 0.001 to 1.0% by mass with respect to the processing solution at the time of use.

As the antifoaming agent, compounds such as general silicon-based self-emulsifying type, emulsifying type, surfactant nonionic HLB 5 or less can be used. Silicon antifoaming agents are preferred.
Among them, emulsification dispersion type and solubilization can be used. The content of the antifoaming agent is preferably in the range of 0.001 to 1.0% by mass with respect to the treatment liquid during use.

  Examples of organic acids include citric acid, acetic acid, succinic acid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malic acid, lactic acid, levulinic acid, p-toluenesulfonic acid, xylenesulfonic acid, phytic acid, and organic phosphonic acid. . The organic acid can also be used in the form of its alkali metal salt or ammonium salt. The content of the organic acid is used in an amount of 0.01 to 0.5% by mass based on the total mass of the treatment liquid.

  Examples of inorganic acids and inorganic salts include phosphoric acid, metaphosphoric acid, primary ammonium phosphate, secondary ammonium phosphate, primary sodium phosphate, secondary sodium phosphate, primary potassium phosphate, secondary potassium phosphate, Examples thereof include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, sodium hydrogen sulfate, nickel sulfate and the like. The content of the inorganic salt is used in an amount of 0.01 to 0.5% by mass based on the total mass of the treatment liquid.

  The treatment agent of the present invention can be obtained by dissolving or dispersing each of the necessary components described above in water. The solid content concentration of the treatment agent is preferably 1 to 20% by mass. A concentrated solution can be prepared and diluted with water at the time of use.

  Examples of the method for bringing the treating agent into contact with the lithographic printing plate precursor according to the invention include the same manual treatment, immersion treatment and mechanical treatment as those described in the plate making method.

By contacting the lithographic printing plate precursor after the image exposure and the processing liquid as described above, the surface of the image area is improved in oleophilicity and ink inking property is improved, and the hydrophilic component penetrates into the image recording layer in the unexposed area. Thus, developability is improved.
Note that the image recording layer in the unexposed area may be removed or not removed at the time of contact with the treatment liquid.

Prior to the above development processing, the lithographic printing plate precursor is exposed through a transparent original image having a line image, a halftone dot image or the like, or imagewise exposed by laser beam scanning or the like using digital data. As a light source suitable for exposure, the same light source as described in the plate making method can be exemplified, but a laser beam is particularly preferable, a solid laser and a semiconductor laser emitting an infrared ray of 760 to 1200 nm, and a light of 250 to 420 nm. Examples include an ultraviolet semiconductor laser that emits radiation, an argon ion laser that emits visible light, and an FD-YAG laser. Among these, from the viewpoint of simplification of plate making, a laser that emits infrared rays or ultraviolet rays that can be operated under white light or yellow light is preferable.

  In the present invention, it is preferable to dry the lithographic printing plate precursor that has been treated with the above-described treatment agent in order to facilitate subsequent handling. Examples of the drying method include natural drying in a room, hot air drying, and using a dryer attached to a gum coater or an automatic processor.

The dried lithographic printing plate precursor is mounted on a printing machine and supplied with printing ink and fountain solution for printing. When printing is performed by supplying printing ink and fountain solution to the lithographic printing plate precursor subjected to the exposure and the above-described treatment, the unexposed area remains after the treatment agent treatment with the printing ink and / or the fountain solution. The image recording layer in the unexposed area which has been formed is dissolved or dispersed and completely removed, and the hydrophilic support surface is exposed in that area. On the other hand, in the exposed portion, the polymerization-cured image recording layer remains to form a printing ink receiving portion (image portion) having a lipophilic surface. As a result, the fountain solution adheres to the exposed hydrophilic surface, the printing ink is deposited on the image recording layer in the exposed area, and printing is started. Here, dampening water or printing ink may be supplied to the printing plate first.
In this way, the lithographic printing plate precursor is developed on an offset printing machine and used as it is for printing a large number of sheets.

(Image recording layer)
The lithographic printing plate precursor used in the plate making method of the present invention has a negative image recording layer containing a water-insoluble polymer. The negative image recording layer is preferably a radically polymerizable image recording layer further containing a polymerization initiator and a polymerizable compound from the viewpoint of easy development and good printing durability.

<Water-insoluble polymer>
As the binder polymer used in the image recording layer of the present invention, any conventionally known binder polymer can be used without particular limitation, but a water-insoluble polymer is preferably used. The water-insoluble polymer that can be used in the present invention is preferably one that does not substantially contain an acid group such as a carboxyl group, a sulfone group, or a phosphate group. By using such a water-insoluble polymer, the film strength, water resistance, and inking property of the image recording layer are improved, and printing durability is improved. Further, the water-insoluble polymer that can be used in the present invention preferably has a glass transition temperature (Tg) of 5 to 85 ° C. By using an aqueous solution having a liquid temperature higher than the glass transition temperature of the water-insoluble polymer as a developer, good developability can be obtained.

As the water-insoluble polymer, any known organic polymer can be used without limitation as long as it contains substantially no acid group and the glass transition temperature (Tg) is in the above range. Is preferred.
As an example of such a water-insoluble polymer, a polymer selected from acrylic resins, polyvinyl acetal resins, polyurethane resins, polyamide resins, epoxy resins, methacrylic resins, styrene resins, and polyester resins is preferable. Especially, an acrylic resin is preferable and a (meth) acrylic acid ester copolymer is preferable. More specifically, an alkyl (meth) acrylate or an aralkyl ester and an ester residue (—COOR) of (meth) acrylate ester may have —CH ₂ CH ₂ O— unit or —CH ₂ CH ₂ NH— unit as R. A copolymer with a (meth) acrylic acid ester containing is particularly preferred. The preferable alkyl group of the said (meth) acrylic-acid alkylester is a C1-C5 alkyl group, and a methyl group is more preferable. Preferable (meth) acrylic acid aralkyl esters include benzyl (meth) acrylate.

  Further, the water-insoluble polymer can have a crosslinking property in order to improve the film strength of the image area. In order to impart crosslinkability to the water-insoluble polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the polymer. The crosslinkable functional group may be introduced by copolymerization. An example of a water-insoluble polymer having an ethylenically unsaturated bond in the molecule is an ester or amide polymer of acrylic acid or methacrylic acid, which is an ester or amide residue (-COOR 'or -CONHR' Mention may be made of polymers wherein R ′) has an ethylenically unsaturated bond.

Examples of residues having an ethylenically unsaturated bond (above R ′) include — (CH ₂ ) _n CR ¹ ═CR ² R ³ , — (CH ₂ O) _n CH ₂ CR ¹ ═CR ² R ³ , _{- (CH 2 CH 2 O)} n CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O- CO—CR ¹ ═CR ² R ³ and — (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group. Represents an alkoxy group or an aryloxy group, and R ¹ and R ² or R ³ may combine with each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadi An enyl residue).
Specific examples of the ester _{residue, -CH 2 CH = CH 2,} ( described in JP Kokoku _{7-21633.) - CH 2 CH 2} O-CH 2 CH = CH 2, -CH 2 C _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 -NHCOO-CH 2 CH = CH 2 and - CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

  The water-insoluble polymer having crosslinkability is, for example, a free radical (a polymerization initiation radical or a growth radical of a polymerization process of a polymerizable compound) is added to the crosslinkable functional group, and the polymerized compound directly or between the polymers. Addition polymerization is performed through the polymerization chain, and a crosslink is formed between the polymer molecules to be cured. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded to each other so that crosslinking between the polymer molecules occurs. Forms and cures.

  The content of the crosslinkable group in the water-insoluble polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol per 1 g of the water-insoluble polymer. More preferably, it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol.

  Further, it is preferable that the binder polymer is hydrophilic from the viewpoint of improving developability with respect to an aqueous solution, and it is important that the binder polymer has good compatibility with the polymerizable compound contained in the image recording layer from the viewpoint of improving printing durability. That is, it is preferable to be lipophilic. From such a viewpoint, in the present invention, it is also effective to copolymerize a hydrophilic group and a lipophilic group in a water-insoluble polymer in order to improve developability and printing durability. Examples of the hydrophilic group include a hydroxy group, a hydroxyethyl group, an ethyleneoxy group, a hydroxypropyl group, a polyoxyethyl group, a polyoxypropyl group, an amino group, an aminoethyl group, an aminopropyl group, an ammonium group, and an amide group. Those having a hydrophilic group are preferably mentioned.

The water-insoluble polymer preferably has a mass average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 20
More preferably, it is 00-250,000. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The water-insoluble polymer may be any of a random polymer, a block polymer, a graft polymer, etc., but is preferably a random polymer.

The water-insoluble polymer may be used alone or in combination of two or more.
The content of the water-insoluble polymer is 5 to 90% by mass, preferably 10 to 70% by mass, and more preferably 10 to 60% by mass with respect to the total solid content of the image recording layer. preferable. Within this range, good image area strength and image formability can be obtained.

<Polymerization initiator>
The polymerization initiator used in the present invention is a compound that initiates and accelerates the polymerization of a compound having a polymerizable unsaturated group by generating radicals by light or thermal energy. As such a radical generator, a known polymerization initiator or a compound having a bond having a small bond dissociation energy can be appropriately selected and used.

  Examples of the compounds that generate radicals include organic halogen compounds, carbonyl compounds, organic peroxides, azo polymerization initiators, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boron compounds, disulfone compounds, and oximes. Examples thereof include ester compounds and onium salt compounds.

  Specific examples of the organic halogen compound include Wakabayashi et al., “Bull Chem. Soc Japan” 42, 2924 (1969), US Pat. No. 3,905,815, Japanese Patent Publication No. 46-4605, JP 48-36281, JP 53-133428, JP 55-3070, JP 60-239736, JP 61-169835, JP 61-169837, JP 62- 58241, JP-A 62-212401, JP-A 63-70243, JP-A 63-298339, P. Examples include compounds described in Hutt, “Journal of Heterocyclic Chemistry” 1 (No. 3), (1970). Of these, oxazole compounds and S-triazine compounds substituted with a trihalomethyl group are preferred.

More preferable examples include s-triazine derivatives in which at least one mono, di, or trihalogen-substituted methyl group is bonded to the s-triazine ring, and oxadiazole derivatives in which the oxadiazole ring is bonded. Specifically, for example, 2,4,6-tris (monochloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [1- (P-methoxyphenyl) -2,4-butadienyl] -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis (trichloromethyl) -s-triazine, 2- ( -Methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (pi-propyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p- Tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenylthio-4,6-bis ( Trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (dibromomethyl) -s-triazine, 2,4,6-tris ( Tribromomethyl) -s-triazine, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2-methoxy-4,6-bis (tribromomethyl) Etc. -s- triazine and the following compounds.

Examples of the carbonyl compound include benzophenone, Michler ketone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-chlorobenzophenone, 4-bromobenzophenone, 2-carboxybenzophenone and other benzophenone derivatives, 2,2-dimethoxy- 2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, α-hydroxy-2-methylphenylpropanone, 1-hydroxy-1-methylethyl- (p-isopropylphenyl) ketone, 1- Hydroxy-1- (p-dodecylphenyl) ketone, 2-methyl- (4 ′-(methylthio) phenyl) -2-morpholino-1-propanone, 1,1,1-trichloromethyl- (p-butylphenyl) Acetophenone derivatives such as ketones, thioxanthone derivatives such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, p- Examples thereof include benzoic acid ester derivatives such as ethyl dimethylaminobenzoate and ethyl p-diethylaminobenzoate.

  As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.

  Examples of the organic peroxide include trimethylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butyl). Peroxy) cyclohexane, 2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydro Peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2, -Oxanoyl peroxide, succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate , Dimethoxyisopropyl peroxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tert-butyl peroxyacetate, tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, tert- Butyl peroxyoctanoate, tert-butyl peroxylaurate, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- ( t-hexyl -Oxycarbonyl) benzophenone, 3,3 ', 4,4'-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogen diphthalate), carbonyldi (t-hexylper) Oxydihydrogen diphthalate) and the like.

  Examples of the metallocene compound include JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, JP-A-2-4705, Various titanocene compounds described in JP-A-5-83588, such as di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, Di-cyclopentadienyl-Ti-bis-2,4-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl, di- -Cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,4,5,6-penta Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4,6-trifluoropheny -1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4 , 5,6-pentafluorophen-1-yl, iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109, and the like.

  Examples of the hexaarylbiimidazole compound include the specification of JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. And, specifically, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-bromophenyl) )) 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2 ′ -Bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5,5 '-Tetraphenylbiimidazole, 2, 2' Bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetrapheni, BR> cryR imidazole, and the like.

  Examples of the organoboron compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188585, JP-A-9-188686, JP-A-9-188710, JP-A 2000-. No. 131837, Japanese Patent Application Laid-Open No. 2002-107916, Japanese Patent No. 2764769, Japanese Patent Application Laid-Open No. 2002-116539, and Kunz, Martin “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”, etc. The organic borate described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, or organic boron oxosulfonium complex, JP-A-6-175554 No. 1, JP-A-6-175553 The organic boron iodonium complex described in JP-A-9-188710, the organic boron phosphonium complex described in JP-A-9-188710, JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP Examples thereof include organoboron transition metal coordination complexes such as 7-306527 and JP-A-7-292014.

  Examples of the disulfone compound include compounds described in JP-A Nos. 61-166544 and 2003-328465.

Examples of the oxime ester compounds include JCS Perkin II (1979) 1653-1660), JCS
Perkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, compounds described in JP 2000-66385 A, compounds described in JP 2000-80068 A, specifically, And the compounds described in the examples are shown.

  Examples of the onium salt compounds include diazonium salts described in SIS Schlesinger, Photogr. Sci. Eng., 18, 387 (1974), TSBal et al, Polymer, 21, 423 (1980), U.S. Pat. 069,055, Ammonium salts described in JP-A-4-365049, etc., phosphonium salts described in US Pat. Nos. 4,069,055 and 4,069,056, European patents Nos. 104 and 143, U.S. Pat. Nos. 339,049 and 410,201, JP-A-2-150848 and JP-A-2-296514, iodonium salts, European Patent 370, 693, 390,214, 233,567, 297,443, 297,442, U.S. Pat.Nos. 4,933,377, 161,811, Nos. 410 and 201 39,049, 4,760,013, 4,734,444, 2,833,827, German Patent 2,904,626, 3,604,580 No. 3,604,581, the sulfonium salts described in JVCrivello et al, Macromolecules, 10 (6), 1307 (1977), JVCrivello et al, J. MoI. Selenonium salt described in Polymer Sci., Polymer Chem. Ed., 17, 1047 (1979), Arsonium salt described in CSWen et al, The, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988) And onium salts.

In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
The onium salt suitably used in the present invention is an onium salt represented by the following general formulas (RI-I) to (RI-III).

In the formula (RI-I), Ar ₁₁ represents an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include an alkyl group having 1 to 12 carbon atoms and a carbon number. 1-12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1-C1 12 alkylamino groups, C1-C12 dialkylamino groups, C1-C12 alkylamide groups or arylamide groups, carbonyl groups, carboxyl groups, cyano groups, sulfonyl groups, C1-C12 thioalkyl groups And a thioaryl group having 1 to 12 carbon atoms. Z ₁₁ ^- represents a monovalent anion, specifically a halogen ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, a sulfate ion Can be mentioned. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion and sulfinate ion are preferable from the viewpoint of stability.

In the formula (RI-II), Ar ₂₁ and Ar ₂₂ each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents include 1 to 1 carbon atoms. 12 alkyl groups, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, Halogen atom, C1-C12 alkylamino group, C1-C12 dialkylamino group, C1-C12 alkylamide group or arylamide group, carbonyl group, carboxyl group, cyano group, sulfonyl group, carbon Examples thereof include a thioalkyl group having 1 to 12 carbon atoms and a thioaryl group having 1 to 12 carbon atoms. Z ₂₁ ^- represents a monovalent anion. Specific examples include halogen ions, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, thiosulfonate ions, and sulfate ions. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoint of stability and reactivity.

In the formula (RI-III), R ₃₁ , R ₃₂ and R ₃₃ are each independently an aryl group, alkyl group, alkenyl group or alkynyl having 20 or less carbon atoms, which may have 1 to 6 substituents. Represents a group. Among them, an aryl group is preferable from the viewpoint of reactivity and stability. Examples of the substituent include an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, Aryloxy group having 1 to 12 carbon atoms, halogen atom, alkylamino group having 1 to 12 carbon atoms, dialkylamino group having 1 to 12 carbon atoms, alkylamide group or arylamide group having 1 to 12 carbon atoms, carbonyl group, carboxyl Group, a cyano group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms. Z ₃₁ ^- represents a monovalent anion. Specific examples include halogen ions, perchlorate ions, hexafluorophosphate ions, tetrafluoroborate ions, sulfonate ions, sulfinate ions, thiosulfonate ions, and sulfate ions. Among these, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable from the viewpoints of stability and reactivity. More preferred are the carboxylate ions described in JP-A No. 2001-343742, and particularly preferred are the carboxylate ions described in JP-A No. 2002-148790.

  Although the specific example of the onium salt compound suitable for this invention is given to the following, it is not limited to these.

  The polymerization initiator is not limited to the above, but a triazine-based initiator, an organic halogen compound, an oxime ester compound, a diazonium salt, an iodonium salt, and a sulfonium salt are more preferable from the viewpoints of reactivity and stability.

These polymerization initiators may be used alone or in combination of two or more. Moreover, these polymerization initiators may be added to the same layer as other components, or another layer may be provided and added thereto. These polymerization initiators are preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass with respect to the total solid content constituting the image recording layer. It can be added in proportions.

<Polymerizable compound>
The polymerizable compound that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one ethylenically unsaturated bond, preferably two or more. It is. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention.
These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of such monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof. Preferably, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, 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.

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

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

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

Examples of other esters include, for example, aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, and JP-A-59-5241. And those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613. Furthermore, the ester monomers described above can also be used as a mixture.
Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

  In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula (A) to a polyisocyanate compound having two or more isocyanate groups. Compound etc. are mentioned.

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

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

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

  Examples of the compound having a vinyl ether group used in the present invention include compounds described in JP-A-2002-029162. Specific examples include tetramethylene glycol divinyl ether, trimethylolpropane trivinyl ether, tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, 1,4-bis {2- (vinyloxy) ethyloxy} Benzene, 1,2-bis {2- (vinyloxy) ethyloxy} benzene, 1,3-bis {2- (vinyloxy) ethyloxy} benzene, 1,3,5-tris {2- (vinyloxy) ethyloxy} benzene, 4 , 4′-bis {2- (vinyloxy) ethyloxy} biphenyl, 4,4′-bis {2- (vinyloxy) ethyloxy} diphenyl ether, 4,4′-bis {2- (vinyloxy) ester Ruoxy} diphenylmethane, 1,4-bis {2- (vinyloxy) ethyloxy} naphthalene, 2,5-bis {2- (vinyloxy) ethyloxy} furan, 2,5-bis {2- (vinyloxy) ethyloxy} thiophene, , 5-bis {2- (vinyloxy) ethyloxy} imidazole, 2,2-bis [4- {2- (vinyloxy) ethyloxy} phenyl] propane {bis (vinyloxyethyl) ether of bisphenol A}, 2,2- Examples include, but are not limited to, bis {4- (vinyloxymethyloxy) phenyl} propane, 2,2-bis {4- (vinyloxy) phenyl} propane, and the like.

About these addition polymerizable compounds, the details of the method of use such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable. A method of adjusting both sensitivity and strength by using a compound) is also effective.
In addition, the selection and use method of the addition polymerization compound is also an important factor for compatibility and dispersibility with other components in the image recording layer (for example, water-insoluble polymer, initiator, colorant, etc.). For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the substrate and the protective layer described later.

The polymerizable compound is used in an amount of preferably 5 to 80% by mass, more preferably 25 to 75% by mass, based on the total solid content constituting the image recording layer. These may be used alone or in combination of two or more.
In addition, the use method of the above-mentioned polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.

<Infrared absorber>
For the image recording layer of the lithographic printing plate precursor that performs imagewise exposure using a light source that emits infrared rays, an infrared absorber can be used in combination with the polymerization initiator. The infrared absorber has a function of converting the absorbed infrared rays into heat, and the polymerization initiator is thermally decomposed by the heat generated at this time to generate radicals. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

Examples of the dye include commercially available dyes and, for example, “Dye Handbook” (edited by the Society of Synthetic Organic Chemistry, Showa 4).
The publicly known thing described in literatures, such as a 5-year publication, can be utilized. 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 Is mentioned.

  Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, The methine dyes described in Japanese Laid-Open Patent Publication Nos. 58-181690 and 58-194595, JP-A 58-112793, JP-A 58-224793, JP-A 59-48187, Naphthoquinone dyes described in Japanese Laid-Open Patent Publication Nos. 59-73996, 60-52940 and 60-63744, and squarylium dyes described in Japanese Laid-Open Patent Publication No. 58-112792. And cyanine dyes described in British Patent 434,875.

  In addition, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also suitable. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59- No. 41363, 59-84248, 59-84249, 59-146063, 59-146061, pyranyl compounds described in JP-A-59-216146, cyanine dyes described in JP-A-59-216146, Patented in US Pat. No. 4,283,475, such as pentamethine thiopyrylium salt, and Japanese Patent Publication Nos. 5-13514 and 5-19702 Pyrylium compounds are also preferably used. Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).

  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 one particularly preferred example is a cyanine dye represented by the following general formula (II).

In general formula (II), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. Xa ^- the Za described later ^- is defined as for, 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 represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring or It is particularly preferable that a 6-membered ring is formed.

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

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

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

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

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

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

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

  The addition of these infrared absorbers to the image recording layer is preferably made the minimum necessary amount in order to suppress side effects that inhibit the polymerization reaction.

  These infrared absorbers are added in a proportion of 0.001 to 50% by mass, preferably 0.005 to 30% by mass, particularly preferably 0.01 to 10% by mass, based on the total solid content of the image recording layer. Can do. Within this range, high sensitivity can be obtained without adversely affecting the uniformity and film strength of the image recording layer.

<Sensitizer>
It is also possible to increase radical generation efficiency by using a sensitizer in combination with the above polymerization initiator in the image recording layer of a lithographic printing plate precursor that performs imagewise exposure using a light source that emits light of 250 to 420 nm. it can.

  Specific examples of the sensitizer include benzoin, benzoin methyl ether, benzoin ethyl ether, 9-fluorenone, 2-chloro-9-fluorenone, 2-methyl-9-fluorenone, 9-anthrone, and 2-bromo-9-anthrone. 2-ethyl-9-anthrone, 9,10-anthraquinone, 2-ethyl-9,10-anthraquinone, 2-t-butyl-9,10-anthraquinone, 2,6-dichloro-9,10-anthraquinone, xanthone 2-methylxanthone, 2-methoxyxanthone, thioxanthone, benzyl, dibenzalacetone, p- (dimethylamino) phenyl styryl ketone, p- (dimethylamino) phenyl p-methylstyryl ketone, benzophenone, p- (dimethylamino) ) Benzophenone (or Michlerketo) ), P- (diethylamino) benzophenone, and the like benzanthrone.

  Furthermore, preferred sensitizers in the present invention include compounds represented by the general formula (III) described in JP-B 51-48516.

In the formula, R ¹⁴ is an alkyl group (for example, methyl group, ethyl group, propyl group, etc.) or a substituted alkyl group (for example, 2-hydroxyethyl group, 2-methoxyethyl group, carboxymethyl group, 2-carboxyethyl group) Etc.). R ¹⁵ represents an alkyl group (eg, methyl group, ethyl group, etc.) or an aryl group (eg, phenyl group, p-hydroxyphenyl group, naphthyl group, thienyl group, etc.).

Z ² is a group of nonmetallic atoms necessary for forming a heterocyclic nucleus containing nitrogen, which is usually used in cyanine dyes, such as benzothiazoles (benzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, etc.), naphtho Thiazoles (α-naphthothiazole, β-naphthothiazole, etc.), benzoselenazoles (benzoselenazole, 5-chlorobenzoselenazole, 6-methoxybenzoselenazole, etc.), naphthoselenazoles (α-naphthoselenazole) , Β-naphthselenazole, etc.), benzoxazoles (benzoxazole, 5-methylbenzoxazole, 5-phenylbenzoxazole, etc.) and naphthoxazoles (α-naphthoxazole, β-naphthoxazole, etc.).

Specific examples of the compound represented by the general formula (III) are those having a chemical structure combining these Z ² , R ¹⁴ and R ¹⁵ , and many exist as known substances. Therefore, it can be used by appropriately selecting from these known ones. Furthermore, preferred sensitizers in the present invention include merocyanine dyes described in JP-B-5-47095 and ketocoumarin compounds represented by the following general formula (IV). Moreover, as the sensitizer used in the present invention, compounds described as sensitizing dyes in JP-A Nos. 2001-100412 and 2003-221517 are also suitable.

Here, R ¹⁶ represents an alkyl group such as a methyl group or an ethyl group.

These sensitizers are preferably from 0.1 to 50 mass%, more preferably from 0.5 to 30 mass%, particularly preferably from 0.8 to 20 mass%, based on the total solid content constituting the image recording layer. Can be added.

<Microcapsule>
In the present invention, as a method for incorporating the above-mentioned image recording layer constituents and other constituents described later into the image recording layer, for example, as described in JP-A Nos. 2001-277740 and 2001-277742. Some of the constituent components can be encapsulated in microcapsules and added to the image recording layer. In that case, each component can be contained in any ratio in and out of the microcapsule.

  A known method can be applied as a method for microencapsulating the constituent components of the image recording layer. For example, as a method for producing microcapsules, a method using coacervation found in U.S. Pat. Nos. 2,800,547 and 2,800,498, U.S. Pat. No. 3,287,154, JP-B-38-19574, 42-446 by the interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304 by polymer precipitation method, US Pat. No. 3,796,669, isocyanate polyol A method using a wall material, a method using an isocyanate wall material found in US Pat. No. 3,914,511, and a urea-formaldehyde system found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802. Or urea formaldehyde-resorcino A method using a wall forming material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as shown in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method using monomer polymerization, spray drying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling method seen in British Patent Nos. 952807 and 967074, etc. However, it is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Moreover, you may introduce | transduce into the microcapsule wall the compound which has crosslinkable functional groups, such as an ethylenically unsaturated bond which can be introduce | transduced into said water-insoluble polymer.

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

<Other image recording layer components>
The image recording layer of the present invention can further contain various additives as required. These will be described below.

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

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

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

The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.

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

  More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Also preferred are the fluorosurfactants described in JP-A-62-170950, JP-A-62-226143 and JP-A-60-168144.

Surfactant can be used individually or in combination of 2 or more types.
The content of the surfactant is preferably 0.001 to 10% by mass, and more preferably 0.01 to 7% by mass, based on the total solid content of the image recording layer.

<Hydrophilic polymer>
In the present invention, a hydrophilic polymer can be contained in order to improve the developability and the microcapsule dispersion stability.
Examples of the hydrophilic polymer include hydroxy group, carboxyl group, carboxylate group, hydroxyethyl group, polyoxyethyl group, hydroxypropyl group, polyoxypropyl group, amino group, aminoethyl group, aminopropyl group, ammonium group, Preferred examples include those having a hydrophilic group such as an amide group, carboxymethyl group, sulfonic acid group, and phosphoric acid group.

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

The hydrophilic polymer preferably has a mass average molecular weight of 5000 or more, more preferably 10,000 to 300,000. The hydrophilic polymer may be any of a random polymer, a block polymer, a graft polymer, and the like.
The content of the hydrophilic polymer in the image recording layer is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the image recording layer.

<Colorant>
In the present invention, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc. And dyes described in Japanese Patent No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.

  These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The addition amount is 0.01 to 10% by mass with respect to the total solid content of the image recording material.

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

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

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

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

<Polymerization inhibitor>
In the image recording layer of the present invention, it is preferable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the radical polymerizable compound during the production or storage of the image recording layer.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t- (Butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the image recording layer.

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

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

<Inorganic fine particles>
The image recording layer of the present invention may contain inorganic fine particles in order to improve the strength of the cured film in the image area. As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate or a mixture thereof can be preferably mentioned. Even if they are not photothermally convertible, they can be used for strengthening the film, enhancing interfacial adhesion by surface roughening, and the like. The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 to 3 μm. Within the above range, it is possible to form a non-image portion excellent in hydrophilicity that is stably dispersed in the image recording layer, sufficiently retains the film strength of the image recording layer, and hardly causes stains during printing. .
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total solid content of the image recording layer.

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

[On-machine development type image recording layer]
The lithographic printing plate precursor used in the lithographic printing method of the present invention has a negative image recording layer which can be removed by printing ink, dampening water or both of them on the support and is cured by exposure. Such an on-press development type negative image recording layer is not particularly limited, but is a polymerizable image containing a polymerization initiator and a polymerizable compound from the viewpoint of easy development and good printing durability. A recording layer is preferred.
Examples of the polymerization initiator and polymerizable compound used in the on-press development type image recording layer include the above-described polymerization initiator and polymerizable compound.

In this on-press development type image recording layer, a binder polymer can be used in order to improve the film strength of the image recording layer. A conventionally well-known thing can be used for a binder polymer without a restriction | limiting, The polymer which has film property is preferable. Examples of such binder polymers include polyurea resins, polyimide resins, novolac-type phenolic resins, synthetic rubbers, natural rubbers, etc., in addition to the above water-insoluble polymers.
The binder polymer may have crosslinkability in order to improve the film strength of the image area. In order to give the binder polymer crosslinkability, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.
Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene. Examples of the polymer having an ethylenically unsaturated bond in the side chain of the molecule are the same as those of the aforementioned water-insoluble polymer.

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

In addition to polymerization initiators, polymerizable compounds and binder polymers, the above-mentioned infrared absorbers, sensitizers, microcapsules, surfactants, colorants, print-out agents, polymerization prohibition An agent, a higher fatty acid derivative, a plasticizer, inorganic fine particles, and a low molecular weight hydrophilic compound can be contained in the above-described addition amount range as necessary.

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

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

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

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

  The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm, and even more preferably from 0.2 to 0.3 mm.

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

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

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

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

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is, but for further improvement in adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation and the like. If necessary, it contains a micropore enlargement treatment, a micropore sealing treatment, and a hydrophilic compound described in Japanese Patent Application Laid-Open Nos. 2001-253181 and 2001-322365. A surface hydrophilization treatment immersed in an aqueous solution can be selected as appropriate. Of course, these enlargement processing and sealing processing are not limited to those described above, and any conventionally known method can be performed.

Sealing treatment includes vapor sealing, single treatment with zirconic fluoride, treatment with an aqueous solution containing an inorganic fluorine compound such as treatment with sodium fluoride, vapor sealing with addition of lithium chloride, sealing with hot water. Hole processing is also possible.
Of these, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and sealing treatment with hot water are preferable.

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

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

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

The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance can be obtained.
The color density of the support is preferably 0.15 to 0.65 as the reflection density value. Within this range, good image formability by preventing halation during image exposure and good plate inspection after development can be obtained.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, it is preferable to provide an undercoat layer of a compound containing a polymerizable group on a support. When an undercoat layer is used, the image recording layer is provided on the undercoat layer. The undercoat layer enhances the adhesion between the support and the image recording layer in the exposed area, and in the unexposed area, the image recording layer is easily peeled off from the support, so that the developability is improved. .
As the undercoat layer, specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of description are mentioned suitably. Particularly preferred compounds include compounds having a polymerizable group such as a methacryl group and an allyl group and a support-adsorptive group such as a sulfonic acid group, a phosphoric acid group and a phosphoric acid ester. A compound having a hydrophilicity-imparting group such as an ethylene oxide group in addition to the polymerizable group and the support-adsorbing group can also be exemplified as a suitable compound.
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 present invention, a water-soluble protective layer (overcoat layer) is formed on the image recording layer in order to prevent scratches in the image recording layer, to block oxygen, and to prevent ablation during high-illuminance laser exposure. Can also be provided.
In the present invention, the exposure is usually performed in the air, but the protective layer is an image of low molecular weight compounds such as oxygen and basic substances present in the air that inhibit the image forming reaction caused by exposure in the image recording layer. This prevents the recording layer from being mixed, and prevents the image formation reaction from being hindered by exposure in the air. Therefore, the properties desired for the protective layer are low permeability of low-molecular compounds such as oxygen, furthermore, good transparency of light used for exposure, excellent adhesion to the image recording layer, and It is preferable that it can be easily removed with an aqueous solution of simple development after exposure. Various studies have been made on the protective layer having such characteristics, and are described in detail, for example, in US Pat. No. 3,458,311 and JP-B-55-49729.

Examples of the material used for the protective layer include water-soluble polymer compounds that are relatively excellent in crystallinity. Specific examples include water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, and polyacrylic acid. Among these, when polyvinyl alcohol (PVA) is used as a main component, the best results are obtained for basic characteristics such as oxygen barrier properties and development removability. The polyvinyl alcohol may be partially substituted with an ester, ether or acetal as long as it contains an unsubstituted vinyl alcohol unit for providing the oxygen barrier property and water solubility necessary for the protective layer, and a part of the other You may have a copolymerization component.
Specific examples of the polyvinyl alcohol include those having a hydrolysis degree of 71 to 100% and a degree of polymerization of 300 to 2400. Specifically, for example, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA manufactured by Kuraray Co., Ltd. -HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405 , PVA-420, PVA-613, and L-8.

The components of the protective layer (selection of PVA, use of additives, etc.), coating amount, etc. are appropriately selected in consideration of fogging properties, adhesion, scratch resistance, etc. in addition to oxygen barrier properties and development removability. Generally, the higher the hydrolysis rate of PVA (that is, the higher the content of the unsubstituted vinyl alcohol unit in the protective layer), and the thicker the film thickness, the higher the oxygen barrier property, which is preferable in terms of sensitivity. . Further, in order to prevent unnecessary polymerization reaction during production and storage, unnecessary fogging during image exposure, image line thickening, and the like, it is preferable that the oxygen barrier property is not too high. Accordingly, the oxygen permeability A at 25 ° C. and 1 atm is preferably 0.2 ≦ A ≦ 20 (cm ³ / m ² · day).

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

  In addition, adhesion to the image area, scratch resistance, and the like are extremely important in handling the lithographic printing plate precursor. That is, when a protective layer that is hydrophilic because it contains a water-soluble polymer compound is laminated on an image recording layer that is oleophilic, the protective layer is easily peeled off due to insufficient adhesion, and polymerization is inhibited by oxygen at the peeled portion. It may cause defects such as poor film hardening due to.

  On the other hand, various proposals have been made to improve the adhesion between the image recording layer and the protective layer. For example, in JP-A-49-70702, a hydrophilic polymer mainly composed of polyvinyl alcohol is mixed with 20 to 60% by mass of an acrylic emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer, etc. It is described that sufficient adhesion can be obtained by laminating on a recording layer. Any of these known techniques can be used in the present invention.

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

The thickness of the protective layer is suitably from 0.1 to 5 μm, particularly preferably from 0.2 to 2 μm.
The method for applying the protective layer is described in detail, for example, in US Pat. No. 3,458,311 and JP-B-55-49729.

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

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. Examples 13 to 21 are reference examples.

(Production of support)

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

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

Next, nitric acid electrolysis was performed in an aqueous solution containing 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., with an aluminum plate serving as an anode with an electric quantity of 50 C / dm ^2. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying. The plate was provided with a direct current anodized film of 2.5 g / m ² at a current density of 15 A / dm ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolyte, then washed with water and dried. A substrate S was obtained.
Then, it processed for 10 second at 30 degreeC with 2.5 mass% sodium silicate aqueous solution, and it washed with water and dried and obtained the support body A.

<Support B>
The substrate S was immersed in a solution heated to 75 ° C. having a pH of 3.7 containing 0.1% by mass of sodium zirconate fluoride and 1% by mass of sodium dihydrogen phosphate for 10 seconds, sealed, and washed with water. Further, in the same manner as the support A, sodium silicate treatment, water washing and drying were performed to obtain a support B.

<Support C>
The substrate S was treated with a 1% by mass aqueous solution of sodium hydroxide at 60 ° C. for 10 seconds to enlarge the pores of the anodized film. By this treatment, the pore diameter of the anodized film was expanded to 20 nm.
After the pore-wide treatment, it is immersed in a solution heated to 75 ° C. at pH 3.7 containing 0.1% by mass of sodium zirconate fluoride and 1% by mass of sodium dihydrogen phosphate, sealed for 10 seconds, and washed with water. Further, in the same manner as the support A, sodium silicate treatment, water washing and drying were performed to obtain a support C.

<Support D>
The substrate S was exposed to a saturated water vapor atmosphere at 100 ° C. for 10 seconds to perform sealing treatment, and similarly to the support A, sodium silicate treatment, water washing and drying were performed to obtain a support D.

  When the center line average roughness (Ra) of the supports A to D was measured using a needle having a diameter of 2 μm, it was 0.51 μm.

The following undercoat liquid (1) was applied to the above supports A to D so that the dry coating amount was 10 mg / m ² to prepare supports (A) to (D) used in the following experiments.

Undercoat liquid (1)
・ Undercoat compound (1) below 0.017g
・ Methanol 9.00 g
・ Water 1.00g

[Examples 1 to 12 and Comparative Examples 1 and 2]
1. Preparation of lithographic printing plate precursor

<Lithographic printing plate precursor (1)>
An image recording layer coating liquid (1) having the following composition is bar-coated on the support (A) and then oven-dried at 160 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. Thus, a lithographic printing plate precursor (1) was obtained.
In addition, the glass transition temperature (Tg) of the water-insoluble polymer (1) can be increased from −100 ° C. to 150 ° C. by 10 ° C./min using a differential scanning calorimeter DSC200 manufactured by Seiko Denshi Kogyo Co., Ltd. It was 45 degreeC when it measured on conditions of a temperature rate.

Image recording layer coating solution (1)
・ The following water-insoluble polymer (1) 0.65 g
・ The following polymerization initiator (1) 0.10 g
・ The following infrared absorbing dye (1) 0.018 g
・ Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.27 g
・ Water-soluble fluorosurfactant (1) 0.044g
・ Methyl ethyl ketone 9.0g

<Lithographic printing plate precursors (2) to (4) and lithographic printing plate precursor (1 ')>
The lithographic printing plate is prepared in the same manner as the lithographic printing plate precursor (1) except that the water-insoluble polymer (1) of the lithographic printing plate precursor (1) is changed to the water-insoluble polymer shown in Table 1 below. Original plates (2) to (4) and a lithographic printing plate precursor (1 ′) for comparison were obtained.

<Lithographic printing plate precursor (5)>
An image recording layer coating liquid (2) having the following composition is bar-coated on the support (A), followed by oven drying at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. Then, a protective layer coating solution (1) having the following composition is coated thereon so that the dry coating mass is 0.5 g / m ^2, and dried at 120 ° C. for 1 minute to obtain a planographic printing plate precursor (5) Got.

Image recording layer coating solution (2)
・ The following polymerization initiator (2) 0.2 g
・ The above water-insoluble polymer (1) 12.0 g
・ Polymerizable compound 6.0g
Isocyanuric acid EO-modified triacrylate (manufactured by Toagosei Co., Ltd., Aronix M-315)
-The following compound C-1 1.5g
・ Royco Crystal Violet 3.0g
・ Thermal polymerization inhibitor 0.1g
N-nitrosophenylhydroxylamine aluminum salt 0.1 g of the above water-soluble fluorosurfactant (1)
・ Methyl ethyl ketone 70.0g

Protective layer coating solution (1)
Polyvinyl alcohol (saponification degree 95 mol%, polymerization degree 800) 40 g
・ Polyvinylpyrrolidone (molecular weight 50,000) 5g
・ Poly (vinyl pyrrolidone / vinyl acetate (1/1)) molecular weight of 75 g
-Nonionic surfactant (1) with the following structure 3g
・ 950g of water

<Lithographic printing plate precursor (6)>
An image recording layer coating liquid (3) having the following composition is bar-coated on the support (A), followed by oven drying at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. Thus, a lithographic printing plate precursor (6) was obtained. The image recording layer coating solution (3) was obtained by mixing and stirring the following photosensitive solution (1) and microcapsule solution (1) immediately before coating. The water-insoluble polymer (6) had a glass transition temperature of 30 ° C.

Photosensitive solution (1)
・ Water-insoluble polymer (6) 0.5g
・ The above polymerization initiator (1) 0.100 g
・ 0.020 g of the above infrared absorbing dye (1)
・ Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.2g
・ 0.044 g of the above water-soluble fluorosurfactant (1)
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g

Microcapsule liquid (1)
・ Microcapsule synthesized as follows (1) 2.640 g
・ Water 2.425g

Synthesis of Microcapsule (1) As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemicals, Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd.) SR444) 3.15 g, 0.35 g of the following infrared absorber (2), 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane (ODB manufactured by Yamamoto Kasei Co., Ltd.), And 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 3 hours. The microcapsule solution thus obtained was diluted with distilled water so that the solid content concentration was 15% by mass. The average particle size was 0.2 μm.

<Lithographic printing plate precursor (7) and comparative lithographic printing plate precursor (2 ')>
The same as the lithographic printing plate precursor (6) except that the water-insoluble polymer (6) of the lithographic printing plate precursor (6) was changed to the water-insoluble polymer (7) and water-soluble polymer shown in Table 2 By the method, a lithographic printing plate precursor (7) and a comparative lithographic printing plate precursor (2 ′) were obtained.

<Lithographic printing plate precursor (8)>
The image recording layer coating solution (3) is bar-coated on the support (A) and then oven-dried at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. On this, the above-mentioned protective layer coating solution (1) was applied so that the dry coating mass was 0.2 g / m ² and dried at 120 ° C. for 1 minute to obtain a lithographic printing plate precursor (8). .

<Lithographic printing plate precursors (9) to (11)>
Instead of the support (A) used in the lithographic printing plate precursor (8), the lithographic printing plate precursor (8) was used except that the support (B), the support (C), and the support (D) were used. Lithographic printing plate precursors (9) to (11) were produced according to the same method as the production.

<Lithographic printing plate precursor (12)>
An image recording layer coating solution (4) having the following composition is bar-coated on the support (A), followed by oven drying at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.4 g / m ^2. Then, a protective layer coating solution (1) having the above composition is applied on the coating layer so that the dry coating mass is 0.5 g / m ^2, and dried at 120 ° C. for 1 minute to obtain a planographic printing plate precursor (12). Got.

Image recording layer coating solution (4)
・ 2.0 g of the above water-insoluble polymer (6)
・ Polymerizable compound 1.5g
Isocyanuric acid EO-modified triacrylate (manufactured by Toa Gosei Co., Ltd., Aronix M-315)
-Compound represented by the following (1) 0.15 g
-Compound represented by (2) below 0.20 g
・ 0.4 g of the compound represented by the following (3)
・ Ethyl violet 0.1g
・ Thermal polymerization inhibitor 0.1g
N-nitrosophenylhydroxylamine aluminum salt 0.02 g of the above water-soluble fluorosurfactant (1)
・ Tetraethylamine hydrochloride 0.06g
・ 17.5 g of 1-methoxy-2-propanol
・ Methyl ethyl ketone 19.0g

2. Platemaking evaluation (development evaluation)
The obtained lithographic printing plate precursors (1) to (4), (6) to (11) and the comparative lithographic printing plate precursors (1 ′) and (2 ′) are combined with a Creo equipped with a water-cooled 40 W infrared semiconductor laser. Imagewise exposure was performed with a Trendsetter 3244VX manufactured by the company under the conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2400 dpi.
The lithographic printing plate precursor of Example 5 was subjected to imagewise exposure under the condition of an energy density of 3 mJ / cm ² using a 375 nm semiconductor laser with an output of 10 mW.
The planographic printing plate precursor of Example 12 was subjected to imagewise exposure under the condition of an energy density of 3 mJ / cm ² using a 405 nm semiconductor laser having an output of 10 mW.
Next, development processing was performed using a developing machine as shown in FIG. 1, and the removability of the unexposed portion of the image recording layer was evaluated. Ion exchange water was used as the developer, and the test was performed under the conditions of liquid temperatures of 25 ° C., 60 ° C., and 90 ° C. Reference numeral 108 in the figure denotes a conveyance roller, and the passage time from the inlet to the outlet is set to 15 seconds. Reference numeral 112 in the figure denotes a rotating brush, which is rotated at a speed of 280 mm / sec in the forward direction with respect to the conveying direction.

  The developed lithographic printing plate is visually observed on its non-image area. If the development is good and the image recording layer does not remain, the developability is ○, and the developability is poor and the image recording layer is not sufficiently removed. The thing evaluated developability as x. The results are shown in Table 3.

3. Evaluation of printing durability The developed lithographic printing plate obtained as described above was subjected to a desensitizing treatment by applying a gum solution GU-7 manufactured by Fuji Photo Film Co., Ltd., and then a printing machine SOR manufactured by Heidelberg. Fountain solution (EU-3 (Effect manufactured by Fuji Photo Film Co., Ltd.) / Water / isopropyl alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (large) Nippon Ink Chemical Co., Ltd.) was used to perform a printing durability test at a printing speed of 6000 sheets per hour. As the number of printed sheets was increased, the image recording layer was gradually worn out and the ink acceptability was lowered, so that the ink density in the printing paper was lowered. Printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing. The results are shown in Table 4.

  As is apparent from the above results, the examples according to the plate making method of the present invention show good developability and printing durability. On the other hand, although a water-insoluble polymer is used, Comparative Example 2 developed at a liquid temperature lower than the Tg lacks developability, and Comparative Example 1 using a water-soluble polymer has good developability, Printing durability is inferior.

[Examples 13 to 21 and Comparative Examples 3 and 4]
1. Preparation of lithographic printing plate precursor

<Lithographic printing plate precursors A and B>
The undercoat liquid (1) was applied on the substrate S obtained by the preparation of the support so that the dry coating amount was 10 mg / m ² , thereby preparing a support E for use in the following experiments.
The image recording layer coating solution (5) is bar-coated on the support E and then oven-dried at 100 ° C. for 75 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. An original A was obtained. Further, a protective layer coating solution (2) having the following composition was further applied onto the lithographic printing plate precursor A using a bar so that the coating amount when dried was 1.0 g / m ^2, and then 100 ° C. for 90 seconds. The lithographic printing plate precursor B was obtained by drying in an oven under the following conditions.
The image recording layer coating solution (5) was obtained by mixing and stirring the following photosensitive solution (2) and microcapsule solution (2) immediately before coating.

Photosensitive solution (2)
-Water-insoluble polymer (6) 0.162g
・ Polymerization initiator (1) 0.100 g
・ The following infrared absorber (2) 0.020 g
・ Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.385 g
・ Fluorosurfactant (1) 0.044g
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g
Microcapsule liquid (2)
-Microcapsule (2) synthesized as follows: 2.640 g
・ Water 2.425g

Synthesis of microcapsule (2) As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75% ethyl acetate solution) 10 g, Aronix M-215 (Toho) Synthetic Co., Ltd. (6.00 g) and Pionein A-41C (Takemoto Yushi Co., Ltd.) 0.12 g were dissolved in ethyl acetate 16.67 g. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 2 hours. The microcapsule solution thus obtained was diluted with distilled water so that the solid content concentration was 15% by mass. The average particle size was 0.2 μm.

Protective layer coating solution (2)
・ 88g of water
・ Polyvinyl alcohol PVA105 (Kuraray Co., Ltd.) 10g
・ Polyethylene glycol (molecular weight 2000) 2g
・ 1g of the following surfactant

<Lithographic printing plate precursor C>
On the support E, the following image recording layer coating solution (6) containing microcapsules (3) of the following synthesis examples is bar coated, oven dried at 70 ° C. for 120 seconds, and a dry coating amount of 1.0 g / An m ² planographic printing plate precursor C was prepared.

Image recording layer coating solution (6)
・ Water 27.0g
-Microcapsule liquid of synthesis example (3) 9.0 g
Acid precursor (compound B below) 0.24g

Synthesis of microcapsule (3) As oil phase components, 4.5 g of bis (vinyloxyethyl) ether of bisphenol A, an adduct of trimethylolpropane and xylylene diisocyanate (Takenate D-110N manufactured by Mitsui Takeda Chemical Co., Ltd.) , Microcapsule wall material) 5 g, Millionate MR-200 (Nippon Polyurethane Co., Ltd. aromatic isocyanate oligomer, microcapsule wall material) 3.75 g, the following infrared absorber (3) 1.5 g, Pionine A41C (Takemoto Yushi ( (Surfactant) 0.1 g was dissolved in 18.4 g of ethyl acetate. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA205 (polyvinyl alcohol manufactured by Kuraray Co., Ltd., saponification degree 88 mol%) was prepared. The oil phase component and the aqueous phase component were emulsified at 12000 rpm for 10 minutes using a homogenizer. Thereafter, a solution obtained by dissolving 0.38 g of tetraethylenepentamine (pentafunctional amine, microcapsule wall cross-linking agent) in 26 g of water was added, and the mixture was stirred for 30 minutes while being cooled with water, and further at 65 ° C. for 3 hours. The microcapsule solution thus obtained had a solid content concentration of 24% by mass and an average particle size of 0.3 μm.

<Lithographic printing plate precursor D>
An image recording layer coating solution (7) having the following composition is bar-coated on the support E, and then oven-dried at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ^2. Then, the protective layer coating solution (2) is coated on the top of the plate using a bar so that the coating amount at the time of drying is 1.0 g / m ^2, and then dried at 120 ° C. for 1 minute to obtain a planographic printing plate An original version D was obtained.

Image recording layer coating solution (7)
-Polymerization initiator (2) 0.2g
・ Water-insoluble polymer (6) 12.0 g
Polymerizable compound, Aronix M-315 (manufactured by Toa Gosei Co., Ltd.) 6.0 g
-The following compound C-1 1.5g
・ Royco Crystal Violet 3.0g
・ Thermal polymerization inhibitor 0.1g
N-nitrosophenylhydroxylamine aluminum salt 0.1 g of fluorosurfactant (1)
・ Methyl ethyl ketone 70.0g

<Lithographic printing plate precursor E>
The image recording layer coating solution (4) is bar-coated on the support E, and then oven-dried at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.4 g / m ^2. Then, the protective layer coating solution (2) is coated thereon using a bar so that the coating amount at the time of drying is 1.0 g / m ^2, and then dried at 120 ° C. for 1 minute to be a planographic printing plate precursor E was obtained.

[Preparation of treatment solution]
Treatment liquids 1 to 5 having compositions shown in Table 5 below were prepared. The unit in the table is [g].

2. Implementation of the planographic printing method The planographic printing plate precursors A to E and the treatment liquids 1 to 5 obtained as described above are used in combinations shown in Table 6, and the planographic printing plate of the present invention is prepared by the exposure, processing and printing methods described below. The printing method was implemented.

<Exposure and processing>
The resulting lithographic printing plate precursors A to C were subjected to imagewise exposure under the conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2400 dpi using a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser. The planographic printing plate precursor D was subjected to imagewise exposure under the condition of an energy density of 3 mJ / cm ² using a 375 nm semiconductor laser having an output of 10 mW. The planographic printing plate precursor E was subjected to imagewise exposure using a 405 nm semiconductor laser with an output of 10 mW under the condition of an energy density of 3 mJ / cm ² .
Next, processing was performed using a processing machine as shown in FIG. The liquid temperature of the treatment liquid was 25 ° C. Reference numeral 108 in the figure denotes a conveyance roller, and the passage time from the inlet to the outlet is set to 15 seconds. Reference numeral 112 in the figure denotes a rotating brush, which is rotated at a speed of 280 mm / sec in the forward direction with respect to the conveying direction. The lithographic printing plate precursor discharged from the treatment tank was dried by natural drying. When the lithographic printing plate precursor after drying was observed, in Examples 13, 18 and 19, the image recording layer was removed by processing in the non-image area of the lithographic printing plate precursor, but the others were not removed.

<Printing>
The naturally dried lithographic printing plate precursor was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg. Dampening water (EU-3 (Effect manufactured by Fuji Photo Film Co., Ltd.) / Water / isopropyl alcohol = 1/89/10 (volume ratio)) and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) After supplying dampening water and ink, 500 sheets were printed at a printing speed of 6000 sheets per hour.
The number of print sheets required until the development of the unexposed portion of the image recording layer was completed and the ink was not transferred to the print sheet as a result was measured as the on-machine development number.
In addition, since a large amount of water-soluble components remain in the exposed portion of the image recording layer at the beginning of printing, the amount of adhering ink is small, and as a result, the ink density transferred to the printing paper is low. Since the water-soluble component on the exposed portion of the image recording layer gradually decreases with the number of printed sheets, the ink density of the printing paper gradually increases with the number of printed sheets. The number of printed sheets that reached the same ink density as the 500th ink density was measured as the number of ink deposits. The results are shown in Table 6.

  From the above results, it can be seen that Examples 13 to 21 of the present invention are clearly superior in on-press developability and ink depositability as compared with no treatment and water treatment of the comparative example.

Schematic diagram of developing machine

Explanation of symbols

106 Developing tank 108 Conveying roller 112 Rotating brush

Claims (10)

Negative-type image recording layer containing a water-insoluble polymer (excluding the following polymers A to C) , a polymerization initiator (excluding organic boron salt compounds) and a polymerizable compound on a hydrophilic support. In the plate making method of a lithographic printing plate in which an image recording layer is removed using an aqueous solution after imagewise exposure, the liquid temperature of the aqueous solution is the glass transition temperature of the water-insoluble polymer. A plate making method of a lithographic printing plate characterized by being higher than (Tg).
Each of the polymers A to C is a polymer composed of the repeating units shown below.

The lithographic printing plate making method according to claim 1, wherein the polymerization initiator is an onium salt (excluding an organic boron salt compound). The polymerization initiator is an onium salt represented by any one of the following general formulas (RI-I) to (RI-III) (excluding an organic boron salt compound). The plate making method of the lithographic printing plate as described.

  In formula (RI-I), Ar ₁₁ Represents an aryl group having 20 or less carbon atoms, which may have 1 to 6 substituents. Z ₁₁ ⁻ Represents a monovalent anion.
  In formula (RI-II), Ar _{twenty one} And Ar _{twenty two} Each independently represents an aryl group having 20 or less carbon atoms, which may have 1 to 6 substituents. Z _{twenty one} ⁻ Represents a monovalent anion.
  In the formula (RI-III), R ₃₁ , R ₃₂ And R ₃₃ Each independently represents an aryl group, alkyl group, alkenyl group, or alkynyl group having 20 or less carbon atoms, which may have 1 to 6 substituents. Z ₃₁ ⁻ Represents a monovalent anion. The lithographic printing plate according to any one of claims 1 to 3, wherein the lithographic printing plate precursor has an undercoat layer containing a compound having a support adhesive group and a polymerizable group in the molecule. Plate making method. The plate making method of a lithographic printing plate according to any one of claims 1 to 4, wherein the image recording layer contains microcapsules. The lithographic printing plate making method according to any one of claims 1 to 5 , wherein the image recording layer is ultraviolet-sensitive. The lithographic printing plate making method according to any one of claims 1 to 5 , wherein the image recording layer is infrared-sensitive. The lithographic printing plate making method according to any one of claims 1 to 5 , wherein the imagewise exposure is performed using a laser that emits light having a wavelength in the range of 760 to 1200 nm. The lithographic printing plate making method according to any one of claims 1 to 5 , wherein the imagewise exposure is performed using a laser that emits light of any wavelength in the range of 250 to 420 nm. The plate making method of a lithographic printing plate according to any one of claims 1 to 9, wherein the hydrophilic support is a support that is subjected to a sealing treatment after anodization .

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