JP2008001059A - Plate surface treating method for plano-graphic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate surface treating means for fully removing the stains stuck on a plate surface without damaging an imaging layer to enhance printability, in a plano-graphic printing plate made from a recently widespread highly sensitive plate. <P>SOLUTION: The plate surface treating method is employed for treating the plate surface of the plano-graphic printing plate with a plate surface cleaning agent, wherein the plano-graphic printing plate is obtained by forming an image on a plano-graphic printing plate original plate with an image forming layer containing an infrared absorber and a protective layer containing an inorganic layered compound carried by a support in this order. The plate surface cleaning agent is an emulsified printing-plate cleaning agent, which contains polysaccharides having a film-forming property extracted from soybean. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plate surface processing method for a lithographic printing plate, and more particularly, to identify a plate surface of a lithographic printing plate formed from a lithographic printing plate precursor having a negative image recording layer containing an infrared absorber and a protective layer. The present invention relates to a plate surface processing method for a lithographic printing plate, comprising processing with a plate surface cleaning agent.

  Lithographic printing is a printing method that skillfully uses the property that water and oil are not essentially mixed, and the printing plate surface accepts water and repels oil-based ink and water repels and accepts oil-based ink. The former is a non-image area, and the latter is an image area. Therefore, when the balance is lost, for example, when the hydrophilicity of the non-image area is deteriorated for some reason, the ink often adheres to the area, resulting in a so-called “soil stain”. There are a wide variety of cases where such scumming occurs, but typical examples include cases where burning or other treatments are applied to make the lithographic printing plate have a high printing durability, The plate surface may be left in the air without being protected with a desensitized gum. Such a phenomenon may occur in the same way even when the printing machine is stopped due to trouble or break time of the printing machine during printing. Therefore, usually, when the printing press is stopped, printing personnel etc. have a habit of applying a desensitized gum solution. Further, when an oleophilic substance adheres to a non-image area of a lithographic printing plate not coated with a desensitized gum and is left to stand, the part becomes sensitized and becomes soiled. For example, traces such as fingerprints appear on the background of printed matter for the same reason. Furthermore, this is a case where the non-image area is scratched. In this case, the ink is clogged in the scratch, and it is gradually made oil-sensitive to become dirty.

The lithographic printing plate having a stain as described above is treated with a so-called plate surface cleaning agent (sometimes referred to as a plate cleaner) for removing ink on the plate surface and restoring the hydrophilicity of the non-image area. Things are customary. As one of such plate surface cleaning agents, one comprising a sodium silicate aqueous solution has been known. However, this plate surface cleaning agent has an effect of extremely high desensitization, but because of its alkalinity, a photosensitive lithographic printing plate developed with an aqueous alkaline developer, for example, Japanese Patent Publication No. 43-28403, US Pat. No. 3 No. 4,046,120, etc., and a positive working photosensitive lithographic printing plate having a photosensitive layer made of an o-quinonediazide compound, or described in JP-A No. 54-98613 and British Patent No. 1,350,521. When used on a lithographic printing plate made from a negative-working photosensitive lithographic printing plate with a binder having an acidic group and a photosensitive layer made of a diazo resin, part of the image area may be damaged or ink adhesion There was a problem of deterioration.
On the other hand, a plate cleaner using oxalic acid has been proposed (see, for example, Patent Document 1). Since this plate cleaner has a weak desensitizing power and has a strong action of corroding a metal support, the surface of the support of an ordinary photosensitive lithographic printing plate (referred to as PS plate) using an aluminum plate as a support. Since the hydrophilic layer (for example, a layer formed by a hydrophilization treatment as described in US Pat. No. 2,714,066) is easily damaged and soiling is caused, Is not suitable.

In general, when smudge occurs during printing, first, the ink on the plate surface is removed with a cleaning agent (kerosene or hydrocarbon solvent), and then treated with a desensitizing agent. The conventional plate surface cleaning agent as described above also needs to be applied after the plate surface is cleaned with an ink cleaning agent, so that the processing steps are complicated when performing the plate surface cleaning treatment. Therefore, in recent years, an emulsification type in which both functions are integrated, that is, a plate surface cleaning agent having an ink cleaning agent function and a desensitizing function has been developed. As such a plate surface cleaning agent, an alkaline emulsification type plate surface cleaning agent has been proposed (see, for example, Patent Document 2), or an acidic emulsification type plate surface cleaning agent has been proposed (see, for example, Patent Document 3). However, such an emulsifying type plate surface cleaning agent is inferior in the stain removing power to the lithographic printing plate subjected to the burning treatment, and is insufficient in the desensitization action for scratches, etc. However, there was a drawback that the stains often recur.
On the other hand, an emulsification type plate surface cleaning agent having a film-forming polysaccharide extracted from soybean as a component has also been proposed (for example, Patent Documents 4 and 5).

In addition, if the plate surface cleaning agent is wiped with a plate cleaning agent in an attempt to completely remove the stains caused by scratches on the printing plate, the plate surface cleaning agent will erode the image portion, and as the printing continues, the image portion wears out. There may be a decrease in printing durability such as a lack of dots or a decrease in printing density.
On the other hand, in the plate making process of a lithographic printing plate precursor, digitized image information is carried by laser light, and the lithographic printing plate precursor is scanned and exposed with the light, and the lithographic printing plate is directly formed without using a lith film. Computer-to-plate (CTP) versions to manufacture are becoming popular. Along with the improvement in productivity of plate making work and the shortening of exposure time, printing plates are required to have high sensitivity and rapid processing. These high sensitivity and rapid processing all lead to insufficient curing of the image area and a decrease in strength, that is, a decrease in printing durability, in the negative type printing plate in which the exposed area is cured by polymerization by light or heat.
Due to such a decrease in the strength of the image layer, if the plate cleaner is used to remove scratches and dirt when the plate is scratched, there is a problem in that the image layer is damaged and the printing durability is reduced. In addition, in the case of a plate cleaner mainly composed of an ink-soluble organic solvent, which is widely used, there is a problem that the image part is damaged by the organic solvent and the image part is lost when imprinted in printing. there were.
Under such circumstances, there has been a demand for means capable of sufficiently removing the stain on the plate surface and improving the printing durability without damaging the image layer even in the high-sensitivity plate which has been spreading in recent years.

US Pat. No. 3,489,561 JP 52-15702 A JP-A-53-2102 JP 2003-54150 A JP 2003-57851 A

  INDUSTRIAL APPLICABILITY The present invention can sufficiently remove stains on the plate surface and improve printing durability without causing damage to the image layer in a lithographic printing plate made from a high-sensitivity plate that has become widespread in recent years. It is to provide printing plate processing means.

As a result of intensive research to achieve the above-mentioned problems, the present inventors have developed an emulsion-type cleaning agent containing a polysaccharide having a film-forming property extracted from soybeans, making a plate from a highly sensitive infrared-sensitive lithographic printing plate precursor. The lithographic printing plate has high performance for removing scratches and stains on the plate surface, and at the same time, it has been found that it is excellent in protecting the image area without damaging the image area and effective in improving printing durability. I came to let you.
Accordingly, the present invention is a plate surface treatment method for treating a plate surface of a lithographic printing plate with a plate surface cleaning agent, wherein the lithographic printing plate comprises an image recording layer containing an infrared absorber on a support, and an inorganic layered compound. Is a lithographic printing plate obtained by forming an image of a lithographic printing plate precursor having a protective layer in this order, and the emulsification containing a film-forming polysaccharide in which the plate surface cleaning agent is extracted from soybean This is a plate surface processing method for a lithographic printing plate, which is a stencil surface cleaning agent.

As the infrared absorber contained in the image recording layer of the lithographic printing plate precursor, a cyanine dye is preferably used.
As a method of forming an image of the above lithographic printing plate, at least a step of image-exposing the lithographic printing plate precursor using an infrared laser, the image-exposed lithographic printing plate precursor is mounted on a printing machine, and the cylinder of the printing machine is mounted. There is a method including a step of making a planographic printing plate by removing an unexposed portion of the image recording layer in an attached state.
The plate surface cleaning agent may contain an organic solvent having an action of dissolving the lithographic printing ink, and among them, an aliphatic hydrocarbon solvent is preferable. The plate surface cleaning agent can further contain at least one compound selected from the group consisting of phosphoric acid, polymerized phosphoric acid, alkali metal salts thereof, and organic phosphonic acid.
Preferred examples of the infrared absorber include compounds represented by the following general formula (D1).

（式中、Ｒ¹およびＲ²は、それぞれ独立に水素原子または炭素原子数１〜１２の炭化水素基を表す。Ｒ¹とＲ²とは互いに結合して環構造を形成していても良い。Ａｒ¹、Ａｒ²は、それぞれ独立に置換基を有していても良い芳香族炭化水素基を表す。Ｙ¹およびＹ²は、それぞれ独立に硫黄原子または炭素原子数１２個以下のジアルキルメチレン基を表す。Ｒ³およびＲ⁴は、それぞれ独立に置換基を有していても良い炭素原子数２０個以下の炭化水素基を表す。Ｒ⁵、Ｒ⁶、Ｒ⁷およびＲ⁸は、それぞれ独立に水素原子または炭素原子数１２個以下の炭化水素基を表す。Ｒ⁹およびＲ¹⁰は、それぞれ独立に置換基を有していても良い炭素原子数６〜１０の芳香族炭化水素基、炭素原子数１〜８のアルキル基、または水素原子を表す。Ｒ⁹とＲ¹⁰は、互いに結合して環構造を形成しても良い。この場合、環構造に窒素原子、酸素原子および硫黄原子からなる群から選ばれるヘテロ原子を１個以上任意に含んでいても良い。Ｘ^-は、対アニオンを示す。ただし、Ｒ¹〜Ｒ⁸のいずれかにスルホ基が置換されている場合は、Ｘ^-は必要ではない。）

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. R ¹ and R ² may be bonded to each other to form a ring structure. Ar ¹ and Ar ² each independently represent an optionally substituted aromatic hydrocarbon group Y ¹ and Y ² each independently represent a sulfur atom or a dialkylmethylene having 12 or less carbon atoms R ³ and R ⁴ each independently represents a hydrocarbon group having 20 or less carbon atoms, which may have a substituent, R ⁵ , R ⁶ , R ⁷ and R ⁸ are each Independently represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms, R ⁹ and R ¹⁰ each independently represents an aromatic hydrocarbon group having 6 to 10 carbon atoms which may have a substituent; .R ⁹ and R ¹⁰ represents an alkyl group or a hydrogen atom, 1 to 8 carbon atoms May be bonded together to form a ring structure In this case, the nitrogen atom in the ring structure, an oxygen atom and a heteroatom selected from the group consisting of sulfur atoms which may optionally contain one or more .X. ^- Represents a counter anion, provided that X ⁻ is not necessary when any of R ^{1 to} R ⁸ is substituted with a sulfo group.)

According to the plate surface treatment method of the present invention, due to the application of the emulsion type plate surface cleaning agent, the cause that occurred in the lithographic printing plate at all stages from plate making to printing at the time of plate making or subsequent storage, during printing, and others. It is possible to remove dirt and scratches based on the above. According to the plate surface processing method of the present invention, stains caused by scratches on the hydrophilic layer of the non-image area can be obtained without damaging the image area, deteriorating the inking property, or corroding and destroying the hydrophilic layer of the non-image area. Can recover.
According to the plate surface processing method of the present invention, the image portion of the planographic printing plate is not damaged, wear of the image portion during printing is suppressed, and adhesion of a hydrophilic substance to the image portion (for example, printing paper) Therefore, the ink receptivity of the image area can be maintained satisfactorily, leading to an improvement in printing durability.

[Emulsification type plate surface cleaning agent]
Specifically, the composition of the emulsifying type plate surface cleaning agent used in the present invention includes (1) a polysaccharide having film-forming properties extracted from soybeans, in addition to (2) phosphoric acid, polymerized phosphoric acid, And at least one compound selected from the group consisting of alkali metal salts and organic phosphonic acids, (3) at least one compound selected from organic carboxylic acids, (4) nitrates, sulfates or bisulfates, and the like. It consists of an aqueous phase and (5) an oil phase containing an organic solvent having a dissolving action for lithographic printing ink. This composition may further contain (6) a surfactant, (7) a water-soluble colloidal substance, (8) a wetting agent, (9) a thixotropic agent, and (10) a pH adjusting agent as required. . In addition to the above components, preservatives, bactericides, dyes and the like may be added to the emulsifying type plate surface cleaning agent used in the present invention.

  The polysaccharide extracted from soybean of the above component (1), that is, water-soluble soybean polysaccharide contains rhamnose, fucose, arabinose, xylose, galactose, glucose, uronic acid and the like in the constituent sugars, and its average molecular weight is 50,000. ~ 1 million. The content of the water-soluble soybean polysaccharide in the emulsifying type plate surface cleaning agent used in the present invention is suitably in the range of 5 to 20% by mass. The soybean polysaccharide is dissolved in water or warm water of 50 ° C. or lower and used as a uniform aqueous solution. A method for producing such a water-soluble soybean polysaccharide is described in JP-A-5-32701. Moreover, as a commercial item, Soya Five-S-LN (Fuji Oil Co., Ltd. product) etc. are mentioned. As the soybean polysaccharide that can be used in the present invention, a 10% by weight aqueous solution having a viscosity (25 ° C.) in the range of 5 to 100 cp is preferably used.

  Examples of the component (2) include phosphoric acid, sodium phosphate, potassium phosphate, lithium phosphate, pyrophosphoric acid, sodium pyrophosphate, potassium pyrophosphate, lithium pyrophosphate, tripolyphosphoric acid, sodium tripolyphosphate, potassium tripolyphosphate, tripolyphosphate. Lithium phosphate, tetraphosphate, sodium tetraphosphate, potassium tetraphosphate, lithium tetraphosphate, hexametaphosphate, sodium hexametaphosphate, potassium hexametaphosphate, lithium hexametaphosphate, inositol hexaphosphate (also known as phytic acid), methylene diphosphonic acid, 1 -Hydroxyethane 1,1-disulfonic acid, nitrilotrisphosphonic acid, N-carboxymethyl N, N-di (methylenephosphonic acid), hexamethylenediamine-tetra (methylenephosphonic acid), ethylenediamine-tetra (medium Lenphosphonic acid), diethylenetriamine-penta (methylenephosphonic acid), N, N-di (carboxymethyl) -N-methylenephosphonic acid, N- (2-hydroxyethyl) -N, N-di (methylenephosphonic acid), N -Hydroxymethyl-N, N'N'-ethylenediaminetris (methylenephosphonic acid), N-hydroxyethyl-N ', N'-diethylethylenediamine-N, N, N', N'-tetra (methylenephosphonic acid), Examples include di (2-hydroxypropylene) triaminepenta (methylenephosphonic acid) and tri (2-hydroxypropylene) tetraaminehexa (methylenephosphonic acid).

These compounds are commercially available, for example from Monsanto Chemical Company as “DEQUESTs” and the Philip A Hant Chemical Corp. Commercially available as "WAYPLEX" from Wayland Chemical Division. The above compounds can be used alone or in combination of two or more.
Of these, phosphoric acid, hexametaphosphoric acid, pyrophosphoric acid, alkali metal salts thereof, and phytic acid are preferably used.
The content of the component (2) in the plate surface cleaning agent is suitably from 0.1 to 15% by mass, more preferably from 0.5 to 10% by mass.

As the organic carboxylic acid of component (3), citric acid, acetic acid, malonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, butyric acid, maleic acid, picolinic acid and the like are used. As the component (3), one or more organic carboxylic acids can be used. Of these, citric acid, malic acid, and maleic acid are preferably used.
The amount of the organic carboxylic acid used is generally 0.5 to 10% by mass, more preferably 1 to 5% by mass, based on the total mass of the plate surface cleaning agent.

The component (4) nitrate is a water-soluble nitrate, such as zinc nitrate, cobalt nitrate, magnesium nitrate, sodium nitrate, potassium nitrate, nickel nitrate, bismuth nitrate, tin nitrate, strontium nitrate, cesium nitrate, cerium nitrate, etc. Metal salts of nitric acid and ammonium nitrate. These nitrates may be used alone or in combination of two or more. In the plate surface cleaning agent used in the present invention, the use amount of the water-soluble metal nitrate is generally 0.5 to 10% by mass of the total mass of the plate surface cleaning agent, and more preferably 1 to 5% by mass. .
Examples of the sulfate or bisulfate of component (4) used in the present invention include sodium sulfate, potassium sulfate, aluminum sulfate and the like. Bisulfate is represented by the general formula M (HSO ₄ ) n (where M is a metal and n is the valence of M), for example, strontium hydrogen sulfate, potassium hydrogen sulfate, calcium hydrogen sulfate, sulfuric acid. Examples include thallium hydrogen, sodium hydrogen sulfate, lead hydrogen sulfate, bismuth hydrogen sulfate, magnesium hydrogen sulfate, and rhodium hydrogen sulfate. One or a combination of two or more of these sulfates and bisulfates may be used. In the plate surface cleaning agent used in the present invention, the amount of sulfate and / or bisulfate used is generally 0.01 to 5% by mass, more preferably 0.1 to 3%, based on the total mass of the plate surface cleaning agent. It is the range of mass%.
The plate surface cleaning agent can contain at least one selected from nitrate, sulfate and bisulfate, and the content of these components (4) is suitably 0.5 to 10% by mass, more preferably 1 to 8% by mass.

  The remaining component of the aqueous phase of the plate surface cleaning agent used in the present invention is water, and the amount thereof is suitably 45 to 85% by mass, more preferably 50 to 80% by mass, based on the total mass of the plate surface cleaning agent. It is.

As an organic solvent (component (5)) having a dissolving action on a lithographic printing ink to be contained as an oil phase of a plate surface cleaning agent used in the present invention, an aliphatic hydrocarbon solvent, an aromatic hydrocarbon solvent, a monoterpene Hydrocarbons, fatty acid triglycerides, and mixtures thereof. Among these, aliphatic hydrocarbon solvents are preferably used from the viewpoint of protecting the image layer of the lithographic printing plate.
Aliphatic hydrocarbon solvents are hydrocarbon solvents that do not have a cyclic structure in the molecule and are linked to straight or branched carbon atoms, and are usually used for cleaning printing inks. A petroleum fraction having a boiling point of 120 to 320 ° C. is particularly useful. An example of the aliphatic hydrocarbon solvent is Exol D-80 (manufactured by Exxon Chemical Co., Ltd.).

  Examples of the aromatic mixed solvent that can be used as the oil phase component include solvent (manufactured by Nippon Petrochemical Co., Ltd.), swazol (manufactured by Maruzen Petrochemical Co., Ltd.), and exsol (manufactured by Exxon Chemical Co., Ltd.).

  As monoterpene hydrocarbons that can be used as the oil phase component, known hydrocarbons can be widely used. For example, α-pinene, β-pinene, 3-carene, camphene, D-limonene, L-limonene, dipentene, terpinolene, α -Terpinene, (alpha) -terpineol, myrcene, osymene, p-cymene, etc. are mentioned. Among these monoterpene hydrocarbons, D-limonene, dipentene and the like are preferable. These monoterpene hydrocarbons are used singly or in combination of two or more.

［式中、Ｒ₁、Ｒ₂及びＲ₃は、同一でも異なっていてもよく、炭素原子数５〜２３の飽和又は不飽和脂肪族炭化水素基を示す。］で表される脂肪酸トリグリセリドを挙げることができる。
上記式中、Ｒ₁、Ｒ₂及びＲ₃は炭素原子数５〜２３、好ましくは炭素原子数７〜１７の飽和又は不飽和脂肪族炭化水素基であって、ヒドロキシル基を有していてもよい。Ｒ₁、Ｒ₂及びＲ₃の具体例としてｎ−ヘキシル基、ｎ−ヘプチル基、ｎ−オクチル基、ｎ−ノニル基、ｎ−デシル基、ｎ−ウンデシル基、ｎ−ドデシル基、ｎ−トリデシル基、ｎ−テトラデシル基、ｎ−ペンタデシル基、ｎ−ヘキサデシル基、ｎ−ヘプタデシル基、ｎ−オクタデシル基、ｎ−ノナデシル基、２−ヘキセニル基、２−ヘプテニル基、２−オクテニル基、ペンタデセニル基、ヘプタデセニル基、９−オクタデセニル基などを挙げることができる。 Moreover, as a fatty acid triglyceride which can be used as an oil phase component, a well-known thing can be widely used, for example, General formula (1):

[In formula, R < ₁ >, R < ₂ > and R < ₃ > may be same or different and show a C5-C23 saturated or unsaturated aliphatic hydrocarbon group. ] The fatty acid triglyceride represented by this can be mentioned.
In the above formula, R ₁ , R ₂ and R ₃ are saturated or unsaturated aliphatic hydrocarbon groups having 5 to 23 carbon atoms, preferably 7 to 17 carbon atoms, and having a hydroxyl group. Good. Specific examples of R ₁ , R ₂ and R ₃ include n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group. Group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, 2-hexenyl group, 2-heptenyl group, 2-octenyl group, pentadecenyl group, A heptadecenyl group, a 9-octadecenyl group, etc. can be mentioned.

Vegetable oil can also be used as the fatty acid triglyceride of component (1) in the plate surface cleaning agent of the present invention. Accordingly, in the above formula, R ₁ —C (O) —, R ₂ —C (O) — and R ₃ —C (O) — may be a constituent fatty acid residue of vegetable oil, such as caproic acid, caprylic acid. , Capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, eicosenoic acid, behenic acid, erucic acid, lignoceric acid, dihydroxystearic acid, ricinoleic acid, etc. Can be residues of
Specific examples of vegetable oils that can be used as fatty acid triglycerides in the present invention include avocado oil, olive oil, camellia oil, apricot oil, kukui nut oil, grape seed oil, sesame oil, safflower oil, sweet almond oil, soybean oil, corn oil, pistachio nut Examples thereof include oil, castor oil, sunflower seed oil, hazelnut oil, jojoba oil, macadamia nut oil, meadowweed oil, peanut oil, rapeseed oil, rose seed oil, and coconut oil. Among these fatty acid triglycerides, safflower oil, soybean oil, rapeseed oil, corn oil and the like are preferably used. You may use such vegetable oil individually by 1 type or 2 types or more.

  In the plate surface cleaning agent used in the present invention, the content of the component (5) is suitably from 3 to 50 mass%, more preferably from 10 to 40 mass%.

Since the above component (5) does not mix with water, it is used in a sufficiently mixed and dispersed state when used. At this time, it is useful to add the surfactant of component (6) to the plate surface cleaning agent for the purpose of enhancing the dispersion stability. Surfactants that can be used include anionic surfactants and nonionic surfactants.
Anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinates, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates. , Alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated castor oil , Sulfated tallow oil, sulfates of fatty acid alkyl esters, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfate Steal salts, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, styrene-anhydrous Examples thereof include partially saponified products of maleic acid copolymers, partially saponified products of olefin-maleic anhydride copolymers, and naphthalene sulfonate formalin condensates. Of these, dialkyl sulfosuccinates, alkyl sulfate esters and alkylbenzene sulfonates are particularly preferably used.

  Nonionic surfactants include 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, fat Acid diethanol amides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, and trialkylamine oxides. Of these, polyoxyethylenated castor oil, sorbitan fatty acid partial esters and the like are preferably used. Two or more of these surfactants may be used in combination. Although the usage-amount of surfactant in a plate surface cleaning agent is not specifically limited, A preferable range is 0.5-10 mass% of the total mass of a plate surface cleaning agent.

  The water-soluble colloidal substance of component (7) is a viscosity modifier, and is suitably used so that the viscosity of the entire plate surface cleaning agent at 25 ° C. is in the range of 10 cps to 1000 cps. Preferred examples include natural products such as dextrin, cyclodextrin, alginate and fibrin derivatives (for example, carboxymethylcellulose, carboxyethylcellulose, hydroxyethylcellulose, methylcellulose, etc.) and modified products thereof, polyvinyl alcohol and derivatives thereof, polyvinylpyrrolidone, poly There are composites such as acrylamide and its copolymers, acrylic acid copolymers, vinyl methyl ether / maleic anhydride copolymers, vinyl acetate / maleic anhydride copolymers, styrene / maleic anhydride copolymers, etc. These substances can be used alone or in combination. The range of use of the water-soluble colloidal material for achieving the viscosity range as described above can be selected from 1 to 24% by mass, more preferably from 3 to 20% by mass, based on the total mass of the plate surface cleaning agent.

In addition to the above components, one or more wetting agents (component (8)) are also useful from the viewpoint of imparting good spreading characteristics to the plate surface cleaning agent and improving the suitability for use by suppressing drying. Formula Suitable wetting agents: (a wherein R is _{C m H 2m (m = 2~6} ), n is 1~500.) HO- (R-O ) n -H represented by Compounds. Examples of preferred compounds are ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol and the like. As other wetting agents, glycerin, sorbitol and pentaerythritol are useful. The effect of the wetting agent used is recognized in the range of 1 to 30% by mass of the total mass of the plate surface cleaning agent, and more preferably in the range of 2 to 20% by mass.

  The thixotropic agent of component (9) lowers the viscosity of the liquid due to dynamic pressure, and when standing, the viscosity increases to improve the working characteristics when the plate surface is treated with a sponge or the like. Suitable thixotropic agents include fine powder of silicic acid, pumice, calcium carbonate, zeolite and the like. The amount used is suitably in the range of 1 to 10% by weight, preferably in the range of 2 to 7% by weight, based on the total weight of the plate surface cleaning agent.

  The plate surface cleaning agent used in the present invention is usually used in an acidic state and is generally adjusted to a pH of 1 to 4. The pH adjuster (component (10)) used to adjust to such a pH range is sulfuric acid, phosphorous acid, citric acid, acetic acid, succinic acid, malonic acid, tartaric acid, malic acid, lactic acid, levulinic acid, butyric acid. Acids such as maleic acid and picolinic acid are used, and alkalis such as sodium hydroxide, potassium hydroxide and lithium hydroxide may be used in combination.

As an example of a method for producing an emulsifying type plate surface cleaning agent used in the present invention, an aqueous phase and an oil phase are respectively prepared, and an oil phase is dropped into the aqueous phase to form a dispersion, which is further emulsified through a homogenizer. Can do.
As a method for using the emulsifying type plate surface cleaning agent, for example, it may be contained in a waste cloth, etc., and the plate surface of the lithographic printing plate may be wiped, left for an appropriate time, and then wiped with water.

Next, the planographic printing plate used in the present invention will be described.
(Image recording layer)
The image recording layer in the original lithographic printing plate used in the present invention contains (A) an infrared absorber, and preferably (B) an iodonium salt, and acts on a negative type. Hereinafter, the components of the image recording layer will be described in detail.
<(A) Infrared absorber>
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, and the absorbance at any wavelength of 400 to 700 nm changes by 0.05 or more due to the action of radicals. If there is no particular limitation, it can be used.
If the amount of change in absorbance at any wavelength of 400 to 700 nm is 0.05 or more, the visibility of the plate will be good, more preferably 0.08 or more, still more preferably 0.11 or more, particularly preferably. It is 0.14 or more.
The wavelength at which the absorbance changes is visible in the visible light region of 400 to 700 nm, more preferably 450 to 680 nm, and even more preferably 500 to 660 nm.

As the dye used as the infrared absorber, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes Is mentioned.
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.

In the present invention, the infrared absorbent is oxidized because it changes in color by changing to an oxidized form of an infrared absorbent having an absorption maximum at a wavelength of 400 to 700 nm by reaction with radicals generated in the exposed area. The easy thing is preferable. From such points, the oxidation potential is preferably 0.45 V (vs. SCE) or less, more preferably 0.40 V (vs. SCE) or less, and 0.35 V (vs. SCE) or less. More preferably.
Although there is no specific lower limit to the oxidation potential of the infrared absorber suitably used, it is preferably 0.10 V (vs. SCE) or more from the viewpoint of the stability of the combination with the (B) iodonium salt. More preferably, it is 15 V (vs. SCE) or more.

As such an infrared absorber, in order to reduce the oxidation potential, those having an electron donating substituent in the chromophore of the infrared absorber are preferable. Preferable electron donating substituents include those having Hammett's σ _para value of −0.10 or less. Specifically, alkyl groups (σ _para value is about −0.12 to −0.20) such as methyl group, ethyl group, propyl group, hydroxyl group (σ _para value −0.37), methoxy group, ethoxy group , Alkoxy groups such as propyloxy group and butoxy group (σ _para value is about −0.24 to −0.45), aryloxy groups such as phenoxy group and toluyloxy group (σ _para value is about −0.32) Amino groups, methylamino groups, ethylamino groups, butylamino groups, dimethylamino groups, diethylamino groups, phenylamino groups, diphenylamino groups and the like (substituted) amino groups (σ _para value is -0.50 to -0.35) And the like, and an alkoxy group having a large electron donating property, a (substituted) amino group, and the like are particularly preferable.

In addition, from the viewpoint of extending the conjugated system of the chromophore and reducing the oxidation potential, a substituent having an aromatic group linked by a hetero atom is also mentioned as a preferable substituent. Examples of the hetero atom linking the aromatic group include a nitrogen atom, an oxygen atom, a phosphorus atom, a sulfur atom, and a selenium atom, and a particularly preferable hetero atom includes a sulfur atom.
Examples of the aromatic group to be linked include hydrocarbon aromatic groups such as a ferro group, naphthyl group, and anthranyl group, and heterocyclic groups such as a furyl group, a thienyl group, a pyrazolyl group, a triazolyl group, an indolyl group, and a benzothiazolyl group, Heterocyclic groups are particularly preferred. These aromatic groups may have a substituent, and preferable substituents include those having the Hammett's σ _para value of −0.10 or less.

  The chromophore of the infrared absorber is preferably a cyanine dye or a polymethine dye such as a (thio) pyrylium dye from the viewpoint of absorption wavelength suitability, solubility, stability, potential characteristics, etc., among which a cyanine dye is preferred and absorption. From the viewpoint of wavelength suitability and potential suitability, heptamethine cyanine dyes having an indolenine skeleton, a benzoindolenine skeleton, a benzothiazole skeleton, a benzoxazole skeleton, and a benzselenazole skeleton are particularly preferable. These polymethine dyes are generally cationic dyes in which the chromophore has a positive charge. From the viewpoint of reducing the oxidation potential, betaine dyes having a negative charge in the chromophore are also preferably used. Examples of the betaine type include those in which a (thio) barbituric acid group is substituted on the polymeon chain, and those in which a squarylium skeleton or a croconium skeleton is incorporated in the polymethine chain.

  Among the dyes having a chromophore as described above, preferred are those represented by the following general formulas (D1) to (D5).

In the above formula, R ¹ and R ² each independently represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and R ¹ and R ² may be bonded to each other to form a ring structure, The ring to be formed is preferably a 5-membered ring or a 6-membered ring. 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. R ⁹ and R ¹⁰ may be the same or different and each may have a substituent, an aromatic hydrocarbon group having 6 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, or hydrogen Represents an atom. R ⁹ and R ¹⁰ may be bonded to each other to form a ring structure. Examples of the ring structure include rings having the following structure.

X ⁻ represents a counter anion. However, when any of R ^{1 to} R ⁸ is substituted with a sulfo group, X ⁻ is not necessary. Preferred X ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, in view of storage stability of the image recording layer coating solution. Hexafluorophosphate ion and aryl sulfonate ion.

In the formula, R ^{1 to} R ⁸ , Ar ¹ , Ar ² , Y ¹ , Y ² and X ⁻ have the same meanings as in the general formula (Dl). Ar ³ represents a monocyclic or polycyclic heterocyclic group containing at least one of a nitrogen atom, an oxygen atom and a sulfur atom, and is a thiazole group, a benzothiazole group, a naphthothiazole group, a thianaphtheno-7 ′, 6 ′, 4,5-thiazole series, oxazole series, benzoxazole series, naphthoxazole series, selenazole series, benzoselenazole series, naphthselenazole series, thiazoline series, 2-quinoline series, 4-quinoline series, 1-isoquinoline series, 3 -Isoquinoline, benzimidazole, 3,3-dialkylbenzoindolenine, 2-pyridine, 4-pyridine, 3,3-dialkylbenzo [e] indole, tetrazole, triazole, pyrimidine, and Heterocyclic groups selected from the group consisting of thiadiazoles are preferred, particularly preferred The Shii heterocyclic group include the following structures.

In the formula, R ^{1 to} R ⁸ , Ar ¹ , Ar ² , Y ¹ and Y ² have the same meanings as in the general formula (Dl). R ¹¹ and R ¹² may be the same or different and each represents a hydrogen atom, an allyl group, a cyclohexyl group, or an alkyl group having 1 to 8 carbon atoms. Z represents an oxygen atom or a sulfur atom.

In the formula, R ¹³ represents a substituent having the following structure. However, R ¹⁴ and R ¹⁵ represents an alkyl group having 1 to 8 carbon atoms, Y ³ is an oxygen atom or a sulfur atom.

In the formula, R ³ , R ⁴ , Ar ¹ , Ar ² , Y ¹ and Y ² have the same meanings as in the general formula (Dl).

Among the dyes having the chromophore as described above, those represented by the general formula (Dl) to the general formula (D3) are more preferable, and those represented by the general formula (Dl) are particularly preferable.
The oxidation potential of the infrared absorber in the present invention is a polar solvent such as acetonitrile and methanol, using a hydrogen electrode, a glass electrode, a quinhydrone electrode, etc. as an indicator electrode, a saturated sweet potato electrode, a silver-silver chloride electrode as a comparison electrode This refers to the value obtained by converting the value measured by potentiometry using a standard calomel electrode.
Specific examples ([IR-1] to [IR-12]) of infrared absorbers having an oxidation potential of 0.45 V (vs. SCE) or less that can be suitably used in the present invention are listed below together with their oxidation potentials. However, the present invention is not limited to these.
The following conditions for measuring the oxidation potential of the infrared absorber were a polar solvent (0.1 M Et ₄ NClO ₄ / MeCN), a rotating disk electrode made of Pt as the indicator electrode, and Ag / AgCl (silver − The value measured using a silver chloride electrode is converted into a value for a standard calomel electrode as a reference electrode.

  When an infrared absorber having a low oxidation potential is used as described above, the curability of the image recording layer is dramatically improved as compared with the case of using an infrared absorber having a high oxidation potential. The cause is not clear, but by using this infrared absorber with a low oxidation potential in combination with an ionic radical generator, the decomposition of the radical generator is promoted, the polymerization reaction proceeds rapidly, and the strength is excellent. It is estimated that an image portion is formed.

The infrared absorber may be used alone or in combination of two or more. In addition, a general-purpose infrared absorber having an oxidation potential exceeding 0.45 V (vs. SCE) can be used in combination as long as the effects of the present invention are not impaired. The content of is preferably 40% by mass or less in the total solid content of the infrared absorber.
Examples of infrared absorbers that can be used in combination include dyes and pigments described in JP-A-7-285275 and JP-A-10-268512.
In the present invention, the amount of these infrared absorbers added is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the total solid content of the image recording layer.

<(B) Iodonium salt>
Iodonium salt generates radicals by energy of light, heat, or both, initiates and accelerates polymerization of a compound having a polymerizable unsaturated group, oxidizes an infrared absorber, and maximizes the wavelength to 400 to 700 nm. It also has a function of changing to an infrared ray absorbent oxidant having absorption. The iodonium salt compound suitably used in the present invention is represented by the following general formula (RI-I).
Ar ¹¹ -I ⁺ -Ar ¹² Z ^11- (RI-I)

In formula (RI-I), Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent.
When the aryl group has a substituent, the substituent includes a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryl having 12 or less carbon atoms. An oxy group is mentioned. Among these, those having an electron donating substituent are preferable because of good color developability. Preferable electron donating substituents include those having Hammett's σ _para value of −0.10 or less.

Specifically, alkyl groups (σ _para value is about −0.12 to −0.20) such as methyl group, ethyl group, propyl group, hydroxyl group (σ _para value −0.37), methoxy group, ethoxy group , Alkoxy groups such as propyloxy group and butoxy group (σ _para value is about −0.24 to −0.45), aryloxy groups such as phenoxy group and toluyloxy group (σ _para value is about −0.32) , Amino groups, methylamino groups, ethylamino groups, butylamino groups, dimethylamino groups, diethylamino groups, phenylamino groups, diphenylamino groups and the like (substituted) amino groups (σ _para value is −0.50 to −0.35) And the like, and an alkoxy group having a large electron donating property, a (substituted) amino group, and the like are particularly preferable.

Z ^11- represents R—COO ⁻ , R—SO ₃ ⁻ , R—SO ₂ ⁻ , R—PO ₃ H ⁻ , R—OPO ₃ H ⁻ , R—PO ₂ H ⁻ , R—OPO ₂ H ⁻ (R Represents an optionally substituted hydrocarbon group having 1 to 30 carbon atoms), an organic anion represented by F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , Represents a counter ion selected from the group consisting of inorganic anions such as PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , H ₂ PO ₃ ⁻ , H ₂ PO ₄ ⁻ , HSO ₃ ⁻ , HSO ₄ ⁻ and NO ₃ ^−. . Among these, R-SO ₃ ⁻ , R—PO ₃ H ⁻ , R—OPO ₃ H ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ and NO ₃ ⁻ are preferable because of excellent on-press developability. R—SO ₃ ^— having a hydrocarbon group substituted with a fluorine atom is particularly preferred.

Specific examples of the iodonium salt compound represented by the general formula (RI-I) that can be suitably used in the present invention are given below.

  The iodonium salt (B) used in the present invention preferably has a maximum absorption wavelength of 400 nm or less, more preferably 330 nm or less, and even more preferably 270 nm or less. By setting the absorption wavelength in the ultraviolet region in this way, the image recording material can be handled under white light.

  These iodonium salt compounds are preferably added in a proportion of 0.5 to 30% by mass, more preferably 1 to 20% by mass, based on the total solid content of the image recording material. These iodonium salt compounds may be used alone or in combination of two or more.

  The (A) infrared absorber and (B) iodonium salt of the present invention are added to the image recording layer, but may be further added to other layers such as a protective layer and an undercoat layer. Furthermore, both components can be microencapsulated and added to the image forming layer or another layer.

<Elements for forming a print image>
In the image recording layer of the present invention, as an element for forming a printed image, (I) an image forming element using radical or cationic polymerization, and (II) thermal fusion or thermal reaction of a hydrophobized precursor are used. At least one of the imaging elements can be used. If the element (I) is used, it becomes a polymerization type image recording layer, and if the element (II) is used, it becomes an image recording layer of a hydrophobized precursor system. Hereinafter, these elements will be described.

(I) Image forming element utilizing polymerization Since the polymerization system element has high image formation sensitivity, the exposure energy can be effectively distributed to printout image formation, and a printed image with good visibility can be obtained. It is suitable for.
The polymerization system element includes a polymerizable compound and a polymerization initiator as basic components.

<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 isocyanate group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or Also suitable are substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a tosyloxy group with monofunctional or polyfunctional alcohols, amines or thiols. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

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

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis -, 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, JP-B-52-30490. And polyfunctional acrylates and methacrylates such as epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid 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, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.

  Examples of the compound having a vinyl ether group that can be 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 usage, such as the structure, single use or combined use, and addition amount, 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 portion, that is, the cured film, those having three or more functionalities are preferable, and further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrene compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
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.

<Polymerization initiator>
The polymerization initiator generates radicals or acids by the action of heat and / or light of the infrared absorber that has absorbed infrared rays, and initiates radical or cationic polymerization of the polymerizable compound. As the radical polymerization initiator in the present invention, a conventionally known polymerization initiator, a compound having a bond having a small bond dissociation energy, or the like can be selected and used in combination with the iodonium salt compound. Examples include onium salts, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, quinonediazide compounds, metallocene compounds, and organic boron salt compounds. The following onium salts are preferred. Used.
In the present invention, examples of the onium salt suitably used as a polymerization initiator used in combination with an iodonium salt compound include a diazonium salt, a sulfonium salt, an ammonium salt, a pyridinium salt, etc. Among them, a diazonium salt and a sulfonium salt are preferable. . A combination with a sulfonium salt is particularly preferable because printing durability is improved.
The diazonium salt and the sulfonium salt preferably used in the present invention are represented by the following general formulas (RI-II) and (RI-III), respectively.

In the formula (RI-II), Ar ²¹ represents an aryl group having 20 or less carbon atoms which may have a substituent. Preferred examples of the substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, an aryloxy group having 12 or less carbon atoms, and 12 or less carbon atoms. Examples thereof include an alkylamino group, a dialkylamino group having 12 or less carbon atoms, an arylamino group having 12 or less carbon atoms, or a diarylamino group having 12 or less carbon atoms. Z ²¹⁻ represents a counter ion having the same ^meaning as Z ¹¹⁻ in formula (RI-1).

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

Specific examples of the onium salt compound that can be used in combination with the iodonium salt compound in the present invention are shown below.

  The addition amount of the radical generator used in combination with the iodonium salt compound is preferably 0.1 to 300% by mass, more preferably 1 to 200% by mass, and still more preferably 5 to 100% with respect to the addition amount of the iodonium salt. % By mass.

<Other image recording layer components>
The polymerization image recording layer further contains additives such as a binder polymer, a surfactant, a colorant, a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic fine particles, and a low molecular weight hydrophilic compound as necessary. Can be made. These will be described below.

<Binder polymer>
The image recording layer can contain a binder polymer. As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and a linear organic polymer having a film property is preferable. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.

  The binder polymer preferably has crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.

Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
An example of a polymer having an ethylenically unsaturated bond in the side chain of the molecule is an ester or amide polymer of acrylic acid or methacrylic acid, wherein the ester or amide residue (-COOR or CONHR R) is ethylene. Examples thereof include polymers having a polymerizable unsaturated bond.

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

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

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

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

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

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

  Specific examples include gum arabic, casein, gelatin, starch derivatives, soya gum, 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 hydroxypyrrole methacrylate, homopolymers and copolymers of hydroxypropyl acrylate, hydroxybutyl methacrylate Homopolymers and copolymers, hydroxybutyl acrylate homopolymers and Polymers, polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, homopolymers of hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more And copolymers, homopolymers and copolymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide, alcohol-soluble nylon, polyethers of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, 2 -Homopolymers and copolymers of acrylamido-2-methyl-1-propanesulfonic acid, homopolymers and copoly of 2-methacryloyloxyethylphosphonic acid Chromatography, and the like.

  The binder polymer preferably has a weight average molecular weight of 5000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 250,000. More preferred. The polydispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.

  The binder polymer may be any of a random polymer, a block polymer, and a graft polymer, but a random polymer is more preferable. Moreover, a binder polymer may be used independently or may be used in mixture of 2 or more types.

The content of the binder polymer is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and preferably 30 to 70% by mass with respect to the total solid content of the image recording layer. Further preferred. Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use a polymeric compound and a binder polymer in the quantity used as 1 / 9-7 / 3 by mass ratio.

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

  A nonionic surfactant 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.

  An anionic surfactant is not specifically limited, A conventionally well-known thing 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.

A cationic surfactant is not specifically limited, A conventionally well-known thing can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
An amphoteric surfactant is not specifically limited, A conventionally well-known thing can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid esters, and imidazolines.

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

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

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

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

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

<Polymerization inhibitor>
It is preferable to add a small amount of a thermal polymerization inhibitor to the image recording layer in order to prevent unnecessary thermal polymerization of the radical polymerizable compound during 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, and it is unevenly distributed on the surface of the image recording layer in the process of drying after coating. Also good. 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 may contain a plasticizer in order to improve on-press developability.
Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in.
The plasticizer content is preferably about 30% by mass or less based on the total solid content of the image recording layer.

<Inorganic fine particles>
The image recording layer may contain inorganic fine particles in order to improve the strength of the cured film in the image area and to improve the on-machine developability in the non-image area.
As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof is preferably exemplified. 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 having excellent hydrophilicity, which 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 may contain a hydrophilic low molecular weight compound for improving on-press developability. Examples of hydrophilic low molecular weight compounds include water-soluble organic compounds such as glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Examples thereof include organic carboxylic acids such as salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid and amino acids, and salts thereof.

<Formation of polymerization-type image recording layer>
Several modes can be used as a method of incorporating the above-mentioned image recording layer constituents into the image recording layer. One is an aspect in which the constituent components are dissolved and applied in a suitable solvent as described in, for example, JP-A-2002-287334, and the other is, for example, JP-A-2001-277740, As described in Japanese Patent Application Laid-Open No. 2001-277742, it is an embodiment (microcapsule type image recording layer) in which the constituent components of the image recording layer are encapsulated in microcapsules and contained in the image recording layer. Further, in the microcapsule type image recording layer, the constituent component can be contained outside the microcapsule. In the microcapsule type image recording layer, it is more preferable that the hydrophobic constituent component is encapsulated in the microcapsule and the hydrophilic constituent component is contained outside the microcapsule. In addition, the (A) infrared absorber and (B) iodonium salt can be included.

  As a method of microencapsulating the above-mentioned image recording layer constituent components, known methods can be applied. 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. Further, a compound having a crosslinkable functional group such as an ethylenically unsaturated bond capable of introducing the binder polymer may be introduced into the microcapsule wall.

  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.

The image recording layer is coated by preparing a coating solution by dispersing or dissolving the necessary components 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-butyrolactone, 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 the coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

(II) Image forming element of hydrophobized precursor system <Hydrophobic precursor>
In the present invention, the hydrophobized precursor is a fine particle capable of converting a hydrophilic image recording layer to hydrophobic when heat is applied. The fine particles are preferably at least one fine particle selected from thermoplastic polymer fine particles and heat-reactive polymer fine particles. Moreover, the microcapsule which included the compound which has a thermoreactive group may be sufficient.

  As thermoplastic polymer fine particles used for the image recording layer of the lithographic printing plate precursor, Research Disclosure No. 33303 of January 1992, JP-A-9-123387, JP-A-9-131850, JP-A-9-171249 The thermoplastic polymer fine particles described in JP-A-9-171250, EP931647 and the like can be mentioned as suitable ones. Specific examples of the polymer constituting the polymer fine particle include homopolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, or the like. Mention may be made of copolymers or mixtures thereof. Among them, more preferred are polystyrene and polymethyl methacrylate.

  The average particle size of the thermoplastic polymer fine particles used in the present invention is preferably 0.01 to 2.0 μm. As a method for synthesizing such thermoplastic polymer fine particles, in addition to emulsion polymerization and suspension polymerization, these compounds are dissolved in a water-insoluble organic solvent, and this is mixed and emulsified with an aqueous solution containing a dispersant. Further, there is a method (solution dispersion method) in which heat is further applied to solidify into fine particles while the organic solvent is being blown away.

  Examples of the heat-reactive polymer fine particles used in the present invention include thermosetting polymer fine particles and polymer fine particles having a heat-reactive group.

  Examples of the thermosetting polymer include a resin having a phenol skeleton, a urea resin (for example, urea or a derivatized urea derivative such as methoxymethylated urea with an aldehyde such as formaldehyde), a melamine resin (for example, melamine or Examples thereof include those obtained by converting the derivatives into resins with aldehydes such as formaldehyde, alkyd resins, unsaturated polyester resins, polyurethane resins, and epoxy resins. Among these, resins having a phenol skeleton, melamine resins, urea resins and epoxy resins are particularly preferable.

  Suitable resins having a phenol skeleton include, for example, phenol resins obtained by converting phenol, cresol and the like with aldehydes such as formaldehyde, hydroxystyrene resins, N- (p-hydroxyphenyl) methacrylamide, and p-hydroxyphenyl methacrylate. Examples thereof include a polymer or copolymer of methacrylamide or acrylamide or methacrylate or acrylate having a phenol skeleton.

  The average particle diameter of the thermosetting polymer fine particles used in the present invention is preferably 0.01 to 2.0 μm. Such thermosetting polymer fine particles can be easily obtained by a solution dispersion method, but may be formed into fine particles when the thermosetting polymer is synthesized. However, it is not restricted to these methods.

  The thermally reactive group of the polymer fine particle having a thermally reactive group used in the present invention may be any functional group that performs a reaction as long as a chemical bond is formed, but is an ethylenically unsaturated group that performs a radical polymerization reaction. Group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.), cationically polymerizable group (for example, vinyl group, vinyloxy group, etc.), isocyanate group that performs addition reaction or its block, epoxy group, vinyloxy group And a functional group having an active hydrogen atom as a reaction partner thereof (for example, an amino group, a hydroxyl group, a carboxyl group, etc.), a carboxyl group for performing a condensation reaction, a hydroxyl group or an amino group as a reaction partner, a ring-opening addition reaction Suitable acid anhydride and reaction partner amino group or hydroxyl group It can gel.

  The introduction of these functional groups into the polymer fine particles may be performed at the time of polymerization, or may be performed using a polymer reaction after the polymerization.

When introduced at the time of polymerization, the monomer having the above functional group is preferably subjected to emulsion polymerization or suspension polymerization. Specific examples of the monomer having the above functional group include allyl methacrylate, allyl acrylate, vinyl methacrylate, vinyl acrylate, 2- (vinyloxy) ethyl methacrylate, p-vinyloxystyrene, p- {2- (vinyloxy) ethyl} styrene, Block isocyanate with glycidyl methacrylate, glycidyl acrylate, 2-isocyanatoethyl methacrylate or alcohol thereof, block isocyanate with 2-isocyanatoethyl acrylate or alcohol, 2-aminoethyl methacrylate, 2-aminoethyl acrylate, 2- Hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, acrylic acid, methacrylic acid, maleic anhydride, bifunctional acrylate, Such as functional methacrylates include, but are not limited to.

  In the present invention, a copolymer of these monomers and a monomer that is copolymerizable with these monomers and does not have a thermally reactive group can also be used. Examples of the copolymer monomer having no heat-reactive group include styrene, alkyl acrylate, alkyl methacrylate, acrylonitrile, vinyl acetate, and the like. It is not limited to.

  Examples of the polymer reaction used when the introduction of the thermally reactive group is carried out after the polymerization include the polymer reaction described in International Publication No. 96/34316 pamphlet.

  Among the polymer fine particles having a heat-reactive group, those in which the polymer fine particles are coalesced by heat are preferable, and those having a hydrophilic surface and being dispersed in water are particularly preferable. The contact angle (water droplets) of the film prepared by applying only polymer fine particles and drying at a temperature lower than the solidification temperature is higher than the contact angle (water droplets) of the film prepared by drying at a temperature higher than the solidification temperature. It is preferable to lower. In order to make the surface of the polymer fine particles hydrophilic in this way, a hydrophilic polymer or oligomer such as polyvinyl alcohol or polyethylene glycol or a hydrophilic low molecular weight compound may be adsorbed on the surface of the polymer fine particles. However, the surface hydrophilization method is not limited to this.

  The solidification temperature of the polymer fine particles having these thermoreactive groups is preferably 70 ° C. or higher, but more preferably 100 ° C. or higher in view of the stability over time. The average particle size of the polymer fine particles is preferably 0.01 to 2.0 μm, more preferably 0.05 to 2.0 μm, and most preferably 0.1 to 1.0 μm. Within this range, good resolution and stability over time can be obtained.

  As the heat-reactive group in the microcapsule encapsulating the compound having a heat-reactive group used in the present invention, the same heat-reactive group as that used for the polymer fine particles having the heat-reactive group is preferable. Can be mentioned.

  As the compound having a thermally reactive group encapsulated in a microcapsule, the same compound as the polymerizable compound is preferably used.

  In addition to the polymerizable compound, a compound having an epoxy group is also preferable. As the compound having an epoxy group, a compound having two or more epoxy groups is preferable. A glycidyl ether compound obtained by a reaction between a polyhydric alcohol or a polyhydric phenol and epichlorohydrin or a prepolymer thereof, and acrylic acid. Examples thereof include a polymer or copolymer of glycidyl or glycidyl methacrylate.

Specific examples include propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl ether of hydrogenated bisphenol A, hydroquinone diglycidyl. Ether, resorcinol diglycidyl ether, diglycidyl ether or epichlorohydrin polyadduct of bisphenol A, diglycidyl ether or epichlorohydrin polyadduct of bisphenol F, diglycidyl ether or epichlorohydride of halogenated bisphenol A Phosphorus polyadduct, diglycidyl ether of biphenyl type bisphenol or epichlorohydrin polyadduct, Novo Click glycidyl ethers such as a resin, further, methyl methacrylate / glycidyl methacrylate copolymer and methacrylic acid-ethyl acrylate / glycidyl methacrylate copolymers and the like.

  Commercially available products of the above compounds include, for example, Epicoat 1001 (molecular weight: about 900, epoxy equivalent: 450 to 500), Epicoat 1002 (molecular weight: about 1600, epoxy equivalent: 600 to 700), Epicoat 1004 (about) manufactured by Japan Epoxy Resin Co., Ltd. 1060, epoxy equivalent 875-975), Epicoat 1007 (molecular weight about 2900, epoxy equivalent 2000), Epicoat 1009 (molecular weight about 3750, epoxy equivalent 3000), Epicoat 1010 (molecular weight about 5500, epoxy equivalent 4000), Epicoat 1100L (epoxy equivalent) 4000), Epicoat YX31575 (epoxy equivalent 1200), Sumitomo Chemical Co., Ltd. Sumiepoxy ESCN-195XHN, ESCN-195XL, ESCN-195XF, and the like.

  Suitable isocyanate compounds for the present invention include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, xylylene diisocyanate, naphthalene diisocyanate, cyclohexanephenylene diisocyanate, isophorone diisocyanate, Examples include hexamethylene diisocyanate, cyclohexyl diisocyanate, and compounds obtained by blocking these with alcohol or amine.

  Suitable amine compounds for the present invention include ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, propylenediamine, polyethyleneimine and the like.

  Examples of the compound having a hydroxyl group suitable for the present invention include a compound having a terminal methylol group, a polyhydric alcohol such as pentaerythritol, and bisphenol / polyphenols.

  Examples of the compound having a carboxyl group suitable for the present invention include aromatic polyvalent carboxylic acids such as pyromellitic acid, trimellitic acid and phthalic acid, and aliphatic polyvalent carboxylic acids such as adipic acid. Suitable acid anhydrides for the present invention include pyromellitic acid anhydride and benzophenone tetracarboxylic acid anhydride.

  The microencapsulation of the compound having a heat-reactive group can be performed by a known method described in the explanation of the polymerization image recording layer.

<Other image recording layer components>
The image recording layer can contain a hydrophilic resin for improving the on-press developability and the film strength of the image recording layer itself. As hydrophilic resin, what has hydrophilic groups, such as a hydroxyl group, an amino group, a carboxyl group, a phosphoric acid group, a sulfonic acid group, an amide group, is preferable, for example. Further, the hydrophilic resin preferably has a group that reacts with the heat-reactive group because it reacts with the heat-reactive group of the hydrophobizing precursor and crosslinks to increase the image strength. . For example, when the hydrophobizing precursor has a vinyloxy group or an epoxy group, the hydrophilic resin preferably has a hydroxyl group, a carboxyl group, a phosphoric acid group, a sulfonic acid group, or the like. Among these, a hydrophilic resin having a hydroxyl group or a carboxyl group is preferable.

  Specific examples of the hydrophilic resin include the polymers described as the hydrophilic binder polymer in the binder polymer. The amount of hydrophilic resin added to the image recording layer is preferably 20% by mass or less, and more preferably 10% by mass or less.

  Further, the hydrophilic resin may be used after being cross-linked to such an extent that an unexposed portion can be developed on-press on a printing press. Cross-linking agents include glyoxal, aldehydes such as melamine formaldehyde resin, urea formaldehyde resin, methylol compounds such as N-methylol urea, N-methylol melamine, and methylolated polyamide resin, divinyl sulfone and bis (β-hydroxyethylsulfonic acid) Active vinyl compounds such as, epoxy compounds such as epichlorohydrin and polyethylene glycol diglycidyl ether, polyamides, polyamines, epichlorohydrin adducts, polyamide epichlorohydrin resins, ester compounds such as monochloroacetic acid esters and thioglycolic acid esters, Polycarboxylic acids such as polyacrylic acid and methyl vinyl ether / maleic acid copolymer, inorganic such as boric acid, titanyl sulfate, Cu, Al, Sn, V, Cr salts Crosslinking agents, such as modified polyamide polyimide resin. In addition, a crosslinking catalyst such as ammonium chloride, a silane coupling agent, a titanate coupling agent, or the like can be used in combination.

  The image recording layer may contain a reaction accelerator that initiates or accelerates the reaction of the thermally reactive group. As the reaction accelerator, the above polymerization initiators can be mentioned as suitable ones.

  Two or more kinds of the reaction accelerators can be used in combination. Further, the reaction accelerator may be added directly to the image recording layer coating solution or may be added in the form of polymer fine particles. The content of the reaction accelerator in the image recording layer is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, based on the total solid content of the image recording layer. Within this range, good reaction initiation or acceleration effect can be obtained without impairing on-press developability.

  In order to further improve the printing durability, a polyfunctional monomer can be added to the image recording layer matrix of the hydrophobized precursor system image recording layer. As this polyfunctional monomer, those exemplified as the polymerizable compound can be used. Among them, preferable monomers include trimethylolpropane triacrylate, pentaerythritol triacrylate, and the like.

  In addition, in the image recording layer of the hydrophobized precursor system, the surfactant, the colorant, the polymerization inhibitor, the higher fatty acid derivative, the plasticizer, the inorganic material described in <Other image recording layer components> of the polymerization image recording layer. Additives such as fine particles and low molecular weight hydrophilic compounds can be contained as required.

<Formation of image recording layer of hydrophobized precursor system>
As in the case of the radical polymerization type image recording layer, the hydrophobized precursor system image recording layer is prepared by dispersing or dissolving the necessary components in a solvent, and coating and drying on a support. It is formed.

The image recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the use, but is generally preferably 0.5 to 5.0 g / m ² .

When the image recording layer of the hydrophobized precursor system is used, a lithographic printing plate precursor capable of on-press development can be easily produced.
On the other hand, the lithographic printing plate precursor of the present invention is not treated (no development) by making the image recording layer of the hydrophobized precursor system a “hydrophilic layer having a crosslinked structure” having sufficient printing durability even when unexposed. It can be applied to the lithographic printing plate precursor of the mold.

  The hydrophilic layer having such a crosslinked structure preferably includes at least one of a hydrophilic resin formed with a crosslinked structure and an inorganic hydrophilic binder resin formed by sol-gel conversion. It is. Of these, the hydrophilic resin will be described first. By adding this hydrophilic resin, there is an advantage that the affinity with the hydrophilic component in the emulsion ink is improved and the film strength of the image recording layer itself is improved. As the hydrophilic resin, those having a hydrophilic group such as hydroxyl, carboxyl, hydroxyethyl, hydroxypropyl, amino, aminoethyl, aminopropyl, carboxymethyl and the like are preferable.

  Specific examples of the hydrophilic resin include the polymers described as the hydrophilic binder polymer in the binder polymer. By using these binder polymers after crosslinking, a hydrophilic layer having a crosslinked structure can be obtained. As the cross-linking agent used for forming the cross-linked structure, those described above are used.

  Further, as a preferred embodiment of the non-processing (non-development) type image recording layer, there can be mentioned those containing an inorganic hydrophilic binder resin formed by sol-gel conversion. A preferred sol-gel conversion binder resin is that a bonding group coming out of a polyvalent element forms a network structure, that is, a three-dimensional cross-linked structure via an oxygen atom, and at the same time, the polyvalent metal is an unbonded hydroxyl group. And a polymer having a resinous structure in which these are mixed, and is in a sol state at a stage where there are many alkoxy groups and hydroxyl groups, and has a network shape as dehydration condensation proceeds. The resin structure becomes strong. Examples of the polyvalent bonding element of the compound having a hydroxyl group or an alkoxy group that performs sol-gel conversion include aluminum, silicon, titanium, and zirconium, and any of these can be used in the present invention. Among these, a sol-gel conversion system using silicon is more preferable, and a system including a silane compound having at least one silanol group capable of sol-gel conversion is particularly preferable. Hereinafter, a sol-gel conversion system using silicon will be described. However, a sol-gel conversion system using aluminum, titanium, and zirconium can be implemented by replacing silicon described below with each element.

  The sol-gel conversion binder resin is preferably a resin having a siloxane bond and a silanol group, and the image recording layer of the present invention includes a coating solution that is a sol system containing at least one compound having a silanol group. Used, it is contained by a process in which condensation of silanol groups proceeds and gels in the process of coating and drying to form a structure of a siloxane skeleton.

  In addition, the image recording layer containing a sol-gel conversion binder resin is used in combination with the hydrophilic resin and the crosslinking agent for the purpose of improving physical properties such as film strength and film flexibility and improving coating properties. It is also possible to do.

The siloxane resin forming the gel structure is represented by the following general formula (I), and the silane compound having at least one silanol group is represented by the following general formula (II). In addition, the material system added to the image recording layer does not necessarily need to be a silane compound of the general formula (II) alone, and is generally an oligomer in which a silane compound is partially condensed or a silane compound and an oligomer of the general formula (II). There may be a mixture of.

The siloxane resin of general formula (I) is formed by sol-gel conversion from a dispersion containing at least one silane compound represented by general formula (II). Here, at least one of R ^{01 to} R ⁰³ in the general formula (I) represents a hydroxyl group, and the other represents an organic residue selected from the symbols R ⁰ and Y in the general formula (II).

Formula (II): (R ⁰ ) _n Si (Y) _4-n

Here, R ⁰ represents a hydroxyl group, a hydrocarbon group or a heterocyclic group. Y represents a hydrogen atom, a halogen atom, —OR ¹ , —OCOR ² , or N (R ³ ) (R ⁴ ). R ¹ and R ² each represent a hydrocarbon group, and R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group or a hydrogen atom. n represents 0, 1, 2 or 3.

The hydrocarbon group or heterocyclic group of R ⁰ is, for example, a linear or branched alkyl group having 1 to 12 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, Pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, etc .; these groups include halogen atoms (chlorine atom, fluorine atom, bromine atom), hydroxyl group, thiol Group, carboxyl group, sulfo group, cyano group, epoxy group, -OR 'group (R' is methyl group, ethyl group, propyl group, butyl group, heptyl group, hexyl group, octyl group, decyl group, propenyl group, Butenyl group, hexenyl group, octenyl group, 2-hydroxyethyl group, 3-chloropropyl group, 2-cyanoethyl group, N, N-dimethylaminoethyl group, 2-butyl group Lomoethyl group, 2- (2-methoxyethyl) oxyethyl group, 2-methoxycarbonylethyl group, 3-carboxyethyl group, 3-carboxypropyl group, benzyl group, etc.), -OCOR '' group (R '' represents Represents the same content as R ′), —COOR ″ group, —COR ″ group, —N (R ′ ″) (R ″ ′) group (R ′ ″ represents a hydrogen atom or R ′ represents the same content as R ′ and may be the same or different from each other), —NHCONHR ″ group, —NHCOOR ″ group, —Si (R ″) ₃ group, —CONHR ″ group and the like.
A plurality of these substituents may be substituted in the alkyl group. A linear or branched alkenyl group having 2 to 12 carbon atoms which may be substituted (for example, vinyl, propenyl, butenyl, pentenyl, hexenyl, octenyl, decenyl, dodecenyl, etc .; Examples of the group substituted by the above group include those having the same contents as the group substituted by the alkyl group), an aralkyl group having 7 to 14 carbon atoms which may be substituted (for example, benzyl group, phenethyl group, 3-phenylpropyl group, naphthylmethyl group, 2-naphthylethyl group and the like; examples of the group substituted by these include those having the same content as the group substituted by the alkyl group, May be substituted), an alicyclic group having 5 to 10 carbon atoms which may be substituted (for example, cyclopentyl group, cyclohexyl group, 2-cyclohexylethyl group, norbornyl group). A group, an adamantyl group, etc .; examples of the group substituted by these include those having the same contents as the group substituted by the alkyl group, and may be substituted plurally), substitution of 6 to 12 carbon atoms An aryl group that may be substituted (for example, a phenyl group or a naphthyl group, and examples of the substituent include those having the same content as the group that is substituted with the alkyl group, and a plurality of substituents may be substituted), or Heterocyclic group which may be condensed, containing at least one atom selected from nitrogen atom, oxygen atom and sulfur atom (for example, pyran ring, furan ring, thiophene ring, morpholine ring, pyrrole ring, thiazole ring, oxazole) Ring, pyridine ring, piperidine ring, pyrrolidone ring, benzothiazole ring, benzoxazole ring, quinoline ring, tetrahydrofuran ring, etc. There. The substituent group includes those groups having the same content which is substituted in the alkyl group, also represents a good), it is substituted plural.

As the substituent of the —OR ¹ group, —OCOR ² group or N (R ³ ) (R ⁴ ) group of Y in the general formula (II), for example, the following substituents are represented. In the —OR ¹ group, R ¹ is an optionally substituted aliphatic group having 1 to 10 carbon atoms [eg, methyl group, ethyl group, propyl group, butyl group, heptyl group, hexyl group, pentyl group, octyl group, Nonyl group, decyl group, propenyl group, butenyl group, heptenyl group, hexenyl group, octenyl group, decenyl group, 2-hydroxyethyl group, 2-hydroxypropyl group, 2-methoxyethyl group, 2- (2-methoxyethyl) Oxyethyl group, 2- (N, N-dimethylamino) ethyl group, 2-methoxypropyl group, 2-cyanoethyl group, 3-methyloxypropyl group, 2-chloroethyl group, cyclohexyl group, cyclopentyl group, cyclooctyl group, chloro Cyclohexyl, methoxycyclohexyl, benzyl, phenethyl, dimethoxybenzyl, methyl A rubenzyl group, a bromobenzyl group, and the like.

In the —OCOR ² group, R ² is an aliphatic group having the same contents as R ¹ or an aromatic group having 6 to 12 carbon atoms which may be substituted (the aromatic group is the same as that exemplified for the aryl group of R above) Are included). In the —N (R ³ ) (R ⁴ ) group, R ³ and R ⁴ may be the same as or different from each other, and each is a hydrogen atom or an aliphatic group having 1 to 10 carbon atoms which may be substituted (for example, And those having the same contents as R ¹ of the —OR ¹ group. More preferably, the total number of carbon atoms of R ³ and R ⁴ is 16 or less. Specific examples of the silane compound represented by the general formula (II) include the following, but are not limited thereto.

  Tetrachlorosilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetra n-propylsilane, methyltrichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrichlorosilane, ethyltrimethoxysilane, ethyltriethoxysilane , N-propyltrichlorosilane, n-propyltrimethoxysilane, n-hexyltrimethoxysilane, n-decyltrimethoxysilane, phenyltrichlorosilane, phenyltrimethoxysilane, dimethoxyditriethoxysilane, dimethyldichlorosilane, dimethyldimethoxysilane , Diphenyldimethoxysilane, phenylmethyldimethoxysilane, triethoxyhydrosilane, trimethoxyhydrosilane, vinyltrichlorosilane, Nyltrimethoxysilane, trifluoropropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylpropyl Methoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, β- (3,4- (Epoxycyclohexyl) ethyltrimethoxysilane and the like.

In the image recording layer, together with the silane compound of the general formula (II), a metal compound capable of forming a film by bonding to a resin at the time of sol-gel conversion such as Ti, Zn, Sn, Zr, and Al can be used in combination. . Examples of the metal compound used include Ti (OR ″) ₄ , TiCl ₄ , Zn (OR ″) ₂ , Zn (CH ₃ COCHCOCH ₃ ) ₂ , Sn (OR ″) ₄ , Sn (CH ₃ COCHCOCH ₃ ) ₄ , Sn (OCOR ″) ₄ , SnCl ₄ , Zr (OR ″) ₄ , Zr (CH ₃ COCHCOCH ₃ ) ₄ , (NH ₄ ) ₂ ZrO (CO ₃ ) ₂ , Al (OR ″) ₃ , Al (CH ₃ COCHCOCH ₃ ) _{3 and the} like. Here, R ″ represents a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or the like.

  Further, in order to accelerate the hydrolysis and polycondensation reaction of the compound represented by the general formula (II) and the metal compound used in combination, it is preferable to use an acidic catalyst or a basic catalyst in combination. As the catalyst, an acid or a basic compound is used as it is or in a state in which it is dissolved in a solvent such as water or alcohol (hereinafter referred to as an acidic catalyst and a basic catalyst, respectively). The concentration at that time is not particularly limited, but when the concentration is high, the hydrolysis and polycondensation rates tend to increase. However, when a basic catalyst having a high concentration is used, a precipitate may be generated in the sol solution. Therefore, the concentration of the basic catalyst is preferably 1 N (concentration in aqueous solution) or less.

  Specific examples of the acidic catalyst include hydrohalic acid such as hydrochloric acid, nitric acid, sulfuric acid, sulfurous acid, hydrogen sulfide, perchloric acid, hydrogen peroxide, carbonic acid, carboxylic acid such as formic acid and acetic acid, and sulfonic acid such as benzenesulfonic acid. Is mentioned. Specific examples of the basic catalyst include, but are not limited to, an ammoniacal base such as aqueous ammonia and amines such as ethylamine and aniline.

  The image recording layer using the sol-gel method described above is particularly preferable as the configuration of the image recording layer according to the present invention. For further details of the above sol-gel method, see Sakuo Sakuo, “Science of Sol-Gel Method” (published by Agne Jofusha Co., Ltd., 1988), Satoshi Hirashima “Functional Thin Film Preparation by Latest Sol-Gel Method” Technology ", published by the General Technology Center (1992).

  The amount of the hydrophilic resin added to the image recording layer having a crosslinked structure is preferably 5 to 70% by mass, more preferably 5 to 50% by mass based on the solid content of the image recording layer.

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

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

In the present invention, among the inorganic layered compounds, fluorine-based swellable mica, which is a synthetic inorganic layered compound, is particularly useful. That is, this swellable synthetic mica and swellable viscosity minerals such as montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, Atomic substitution is significantly greater than other viscous minerals. As a result, the lattice layer is deficient in positive charges, and cations such as Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers in order to compensate for this. The cations present between these layers are called exchangeable cations and exchange with various cations. In particular, when the cation between the layers is Li ⁺ or Na ⁺ , the bond between the layered crystal lattices is weak because the ionic radius is small, and the layer swells greatly with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have a strong tendency and are useful in the present invention, and swellable synthetic mica is particularly preferably used.

  As the shape of the inorganic layered compound used in the present invention, from the viewpoint of diffusion control, the smaller the thickness, the better. The plane size is as long as it does not hinder the smoothness of the coated surface or the transmittance of actinic rays. Larger is better. Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

  As for the particle diameter of the inorganic stratiform compound used in the present invention, the average major axis is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

  When the inorganic layered compound particles having such a large aspect ratio are contained in the protective layer, the coating film strength is improved, and the permeation of oxygen and moisture can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the image forming property of the lithographic printing plate precursor is not deteriorated due to changes in humidity, and the storage stability is excellent.

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

  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 in an on-press development process 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.

In the protective layer, a binder is preferably used together with the inorganic layered compound.
The binder is not particularly limited as long as it has a good dispersibility of the inorganic layered compound and can form a uniform film in close contact with the image recording layer, and any of water-soluble polymers and water-insoluble polymers can be used. It can be appropriately selected and used. Specifically, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, partially saponified product of polyvinyl acetate, ethylene-vinyl alcohol copolymer, water-soluble cellulose derivative, gelatin, starch Examples thereof include water-soluble polymers such as derivatives and gum arabic, and polymers such as polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, and cellophane. These may be used in combination of two or more as required.

  Of these, water-soluble polymers are preferable from the viewpoint of easy removal of the protective layer remaining in the non-image area and handling properties during film formation, and water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid. Acrylic resin, gelatin, gum arabic, and the like are preferable. Among them, polyvinyl alcohol, polyvinyl pyrrolidone, gelatin can be applied from the viewpoint of being able to be applied using water as a solvent and easily removed by dampening water during printing. More preferred are gum arabic and the like.

The polyvinyl alcohol that can be used in the protective layer according to the present invention may be partially substituted with an ester, an ether, and an acetal as long as it contains a substantial amount of an unsubstituted vinyl alcohol unit having the necessary water solubility. Similarly, a part may contain other copolymerization components. Specific examples of polyvinyl alcohol include those having a hydrolysis degree of 71 to 100 mol% and a polymerization degree of 300 to 2400.
Specifically, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA124H, PVA-CS, PVA-CST, PVA-HC, PVA manufactured by Kuraray Co., Ltd. -203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420 , PVA-613, L-8 and the like. Examples of the copolymer include 88-100 mol% hydrolyzed polyvinyl acetate chloroacetate or propionate, polyvinyl formal, polyvinyl acetal, and copolymers thereof.

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

  Known additives such as a surfactant for improving the coating property and a water-soluble plasticizer for improving the physical properties of the film can be added to the protective layer coating solution. Examples of the water-soluble plasticizer include propionamide, cyclohexanediol, glycerin, sorbitol and the like. A water-soluble (meth) acrylic polymer can also be added. Furthermore, a known additive for improving the adhesion with the image recording layer and the temporal stability of the coating solution may be added to the coating solution.

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

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

[Support]
The support used for the lithographic printing plate precursor used in the present invention is not particularly limited as long as it is a dimensionally stable plate. 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. dm 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.

  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, 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, it is preferable to provide an antistatic layer on the hydrophilic layer side or the opposite side or both sides of the support body. 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 with 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.

[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 an organic polymer compound described in JP-A-5-45885, an organometallic compound or an inorganic metal compound described in JP-A-6-35174. A coating layer made of a metal oxide obtained in this way 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.

[Undercoat layer]
In the lithographic printing plate precursor used in the present invention, an undercoat layer can be provided between the image recording layer and the support, if necessary. In particular, in the case of an on-press development type lithographic printing plate precursor, the undercoat layer tends to peel off from the support of the image recording layer in the unexposed area, so that on-press developability is improved. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat insulating layer, so that heat generated by exposure does not diffuse to the support and can be used efficiently, so that high sensitivity can be achieved. There are advantages.
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. Preferred examples include phosphorus compounds having an ethylenic double bond reactive group described in the publication.
The most preferable undercoat layer includes a polymer resin obtained by copolymerization of a monomer having an adsorbing group / a monomer having a hydrophilic group / a monomer having a crosslinkable group.

An essential component of the polymer undercoat is an adsorptive group on the surface of the hydrophilic support. The presence or absence of adsorptivity on the surface of the hydrophilic support can be determined, for example, by the following method.
A coating night is prepared by dissolving the test compound in a readily soluble solvent, and the coating night is coated and dried on the support so that the coating amount after drying is 30 mg / m ² . Next, the support coated with the test compound is sufficiently washed with a readily soluble solvent, and then the residual amount of the test compound that has not been removed by washing is measured to calculate the adsorbed amount of the support. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, liquid chromatography measurement and the like. The compound having the support adsorptivity is a compound that remains at 0.5 mg / m ² or more even after the washing treatment as described above.

The adsorptive group on the surface of the hydrophilic support is a substance (for example, metal, metal oxide) or a functional group (for example, hydroxyl group) existing on the surface of the hydrophilic support and a chemical bond (for example, ionic bond, hydrogen bond). , Coordination bond, bond by intermolecular force). The adsorptive group is preferably an acid group or a cationic group.
The acid group preferably has an acid dissociation constant (pKa) of 7 or less. Examples of acid groups include phenolic hydroxyl groups, carboxyl groups, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ —, and —COCH ₂ COCH ₃ . A phosphoric acid group (—OPO ₃ H ₂ , —PO ₃ H ₂ ) is particularly preferred. These acid groups may be metal salts.
The cationic group is preferably an onium group. Examples of the onium group include an ammonium group, a phosphonium group, an arsonium group, a stibonium group, an oxonium group, a sulfonium group, a selenonium group, a stannonium group, and an iodonium group. An ammonium group, a phosphonium group and a sulfonium group are preferred, an ammonium group and a phosphonium group are more preferred, and an ammonium group is most preferred.

Particularly preferred examples include compounds represented by the following formula (III) or (IV).

In the formula (III), R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms. R ¹ , R ² and R ³ are each independently preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferred is a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom.
In the formula (III), X is an oxygen atom (—O—) or imino (—NH—).
X is more preferably an oxygen atom. In the formula (III), L is a divalent linking group. L is a divalent aliphatic group (alkylene group, substituted alkylene group, alkenylene group, substituted alkenylene group, alkynylene group, substituted alkynylene group), divalent aromatic group (arylene group, substituted arylene group) or divalent Or an oxygen atom (—O—), a sulfur atom (—S—), an imino (—NH—), a substituted imino (—NR—, R is an aliphatic group, an aromatic group Or a combination with a heterocyclic group) or carbonyl (—CO—).

  The aliphatic group may have a cyclic structure or a branched structure. The number of carbon atoms in the aliphatic group is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10. The aliphatic group is preferably a saturated aliphatic group rather than an unsaturated aliphatic group. The aliphatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aromatic group, and a heterocyclic group.

The number of carbon atoms in the aromatic group is preferably 6 to 20, more preferably 6 to 15, and most preferably 6 to 10. The aromatic group may have a substituent. Examples of the substituent include a halogen atom, a hydroxyl group, an aliphatic group, an aromatic group, and a heterocyclic group.
The heterocyclic group preferably has a 5-membered or 6-membered ring as the heterocycle. The heterocycle may be condensed with another heterocycle, aliphatic ring or aromatic ring. The heterocyclic group may have a substituent. Examples of substituents include halogen atoms, hydroxyl groups, oxo groups (═O), thioxo groups (═S), imino groups (═NH), substituted imino groups (═N—R, R is an aliphatic group, aromatic Group or heterocyclic group), aliphatic group, aromatic group and heterocyclic group.
L is preferably a divalent linking group containing a plurality of polyoxyalkylene structures. The polyoxyalkylene structure is more preferably a polyoxyethylene structure. In other words, L preferably contains — (OCH ₂ CH ₂ ) _n — (n is an integer of 2 or more).

In the formula (III), Z is a functional group that adsorbs to the surface of the hydrophilic support. Y is a carbon atom or a nitrogen atom. When Y is a nitrogen atom and L is connected to Y to form a quaternary pyridinium group, Z is not essential because it exhibits adsorptivity itself.
The adsorptive functional group is as described above.
R ¹ , Y, L and Z in the formula (IV) have the same meanings as in the formula (III).
Examples of typical compounds represented by formula (III) or (IV) are shown below.

  Preferred hydrophilic groups for the polymer undercoat that can be used in the present invention include those having a sulfonic acid group exhibiting high hydrophilicity. Specifically, methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, acrylamide t-butylsulfonic acid, 2-acrylamido-2-methyl Examples thereof include propanesulfonic acid, sodium salt of (3-acryloyloxypropyl) butylsulfonic acid, and amine salt. Among them, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferable because of hydrophilic performance and ease of handling in synthesis.

The undercoat polymer resin used in the present invention preferably has crosslinkability in order to improve adhesion to the image area. In order to impart crosslinkability to the polymer resin for the undercoat, a crosslinkable functional group such as an ethylenically unsaturated bond is introduced into the side chain of the polymer or has a counter charge with the polar substituent of the polymer resin. It can be introduced by forming a salt structure with a compound having a substituent and an ethylenically unsaturated bond.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid where the ester or amide residue (R of -COOR or -CONHR) is Mention may be made of polymers having an ethylenically unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{bond, - (CH 2) n CR} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ₁ ═CR ₂ R ₃ and — (CH ₂ CH ₂ O) ₂ —X (wherein R _{1 to} R ₃ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, 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 O—Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ OCO—CH═CH _2. Is mentioned.

  The content of the crosslinkable group in the polymer resin for undercoat (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.01 to 10.0 mmol, more preferably 1 g per 1 g of the polymer resin. Is 0.1 to 7.0 mmol, most preferably 0.2 to 5.5 mmol. Within this range, both good sensitivity and dirtiness and good storage stability can be obtained.

The undercoat polymer resin preferably has a mass average molecular weight of 5000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1000 or more, preferably 2000 to 250,000. It is more preferable that The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The undercoat polymer resin may be a random polymer, a block polymer, a graft polymer, or the like, but is preferably a random polymer.

  As the copolymerization substituent for the polymer undercoat that can be used in the present invention, conventionally known copolymerization substituents can be used without limitation. Examples of hydrophilic copolymerization substituents include hydroxy groups, carboxyl groups, carboxylate groups, Hydrophilicity such as hydroxyethyl group, polyoxyethyl group, hydroxypropyl group, polyoxypropyl group, amino group, aminoethyl group, aminopropyl group, ammonium group, amide group, carboxymethyl group, sulfonic acid group, phosphoric acid group Those having a group are preferred.

  Specific examples include 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, hydroxyethyl acrylate Homopolymers and copolymers, homopolymers and copolymers of hydroxypropyl methacrylate, homopolymers and copolymers of hydroxypropyl acrylate, homopolymers and copolymers of hydroxybutyl methacrylate, homopolymers and copolymers of hydroxybutyl acrylate, polyethylene glycols, hydroxypropylene polymers, Polyvinyl alcohols, hydrolysis degree is 60 mol% or more, preferably 8 Hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, homopolymers and copolymers of acrylamide, homopolymers and polymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide, polyvinyl pyrrolidone, alcohol soluble nylon 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin polyether.

The undercoat polymer resin may be used alone or in combination of two or more. Two or more compounds having a functional group that adsorbs to the surface of the hydrophilic support may be used in combination.
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.

[Lithographic printing method]
In the method for making a lithographic printing plate from the lithographic printing plate precursor according to the present invention, the lithographic printing plate precursor is imagewise exposed with an infrared laser. Although the infrared laser used is not specifically limited, The solid laser and semiconductor laser which radiate | emit infrared rays with a wavelength of 760-1200 nm are mentioned suitably. The output of the infrared laser is preferably 100 mW or more. In order to shorten the exposure time, it is preferable to use a multi-beam laser device.
The exposure time per pixel is preferably within 20 μsec. Moreover, it is preferable that irradiation energy amount is 10-300 mJ / cm < ² >.

After the lithographic printing plate precursor is imagewise exposed with an infrared laser, oil-based ink and an aqueous component are supplied and printed without any development process.
Specifically, after exposing the lithographic printing plate precursor with an infrared laser, it is mounted on a printing machine without passing through a development process, or after printing the lithographic printing plate precursor on the printing machine, And a method of printing with exposure with an infrared laser.

After the lithographic printing plate precursor is imagewise exposed with an infrared laser, the aqueous component and the oil-based ink are supplied and printed without going through a development processing step such as a wet development processing step. In this case, in the exposed portion of the image recording layer, the image recording layer cured by exposure forms an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed portion, the uncured image recording layer is dissolved or dispersed and removed by the supplied aqueous component and / or oil-based ink, and a hydrophilic surface is exposed at the portion. As a result, the aqueous component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the image recording layer in the exposed area, and printing is started.
In the case of an untreated lithographic printing plate precursor, the unexposed area is a hydrophilic surface, and the exposed area is converted to an oleophilic surface. Therefore, when an aqueous component and / or oil-based ink is supplied, the unexposed area is water-soluble. The component adheres, and the oil-based ink selectively adheres to the exposed portion, and printing can be performed as it is.
Here, an aqueous component or oil-based ink may be supplied first to the plate surface, but in an on-press development type lithographic printing plate precursor, the aqueous component is contaminated by the image recording layer in the unexposed area. It is preferable to supply the oil-based ink first from the viewpoint of preventing the ink. As the aqueous component and oil-based ink, fountain solution and printing ink for ordinary lithographic printing are used.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

(Create support)
In order to remove rolling oil on the surface of an aluminum plate (material 1050) having a thickness of 0.3 mm, a degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution. 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 nitric acid solution (containing 0.5% by mass aluminum ions), and the liquid temperature was 50 ° C. The AC power supply waveform is electrochemical roughening treatment using a trapezoidal rectangular wave AC with a time TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave AC. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Furthermore, (including 0.5 mass% of aluminum ion) 0.5% by weight aqueous hydrochloric acid solution, at a liquid temperature of 50 ° C. of the electrolytic solution, an aluminum plate electric quantity 50C / dm ² at the anode conditions, and nitric acid electrolysis An electrochemical surface roughening treatment was performed in the same manner, followed by washing with water by spraying. The plate was provided with a DC 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 electrolytic solution, then washed with water and dried. The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm. Furthermore, the following undercoat liquid (1) was applied so that the dry coating amount was 6 mg / m ² to obtain a support.

Undercoat liquid (1)
Undercoat compound (1) 0.017 g
Methanol 9.00g
1.00 g of water

1. Preparation of lithographic printing plate precursor An image recording layer coating solution (mixture of a photosensitive solution and a microcapsule solution) having the following composition was bar-coated on the support, and then oven-dried at 100 ° C. for 60 seconds to obtain a dry coating amount of 1 An image recording layer of 0.0 g / m ² was formed. Further thereon, a protective layer coating solution having the following composition was coated with a bar and then oven-dried at 125 ° C. for 75 seconds to form a protective layer to obtain lithographic printing plate precursors (1) and (2) for the present invention. It was.
Further, only the addition amount of the scale-like synthetic mica in the protective layer coating solution was set to 0 from the configuration of the original plate (1) and replaced with the same amount of distilled water to obtain an original plate (3) for a comparative example.
The image recording layer coating solution was obtained by mixing the following photosensitive solution and the following microcapsule solution immediately before coating and stirring.

Photosensitizer original plate (1) original plate (2)
Binder polymer (1) 0.15 g 0.15 g
Iodonium salt; OI-3 described in the text 0.16 g 0.16 g
Infrared absorber (1); IR-8 described in the text 0.03 g −
Infrared absorber (2); IR-4-0.03 g described in the text
Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.35 g 0.35 g
Fluorosurfactant (1) 0.04g 0.04g
Methyl ethyl ketone 1.0g 1.0g
1-methoxy-2-propanol 7.82 g 7.82 g

Microcapsule liquid Microcapsule dispersion (A) synthesized as follows 2.397 g
2.202 g of water
Synthesis of Microcapsule Dispersion (A) Trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75 mass% ethyl acetate solution) 10.0 g as an oil phase component, polymerization Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) and 0.12 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) 0.16 g as ethyl acetate were dissolved in 16.67 g of ethyl acetate.
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 12,000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 2 hours. The microcapsule liquid thus obtained was diluted with distilled water so that the solid content concentration was 15% by mass to obtain a microcapsule dispersion (A). The average particle size was 0.23 μm.

Protective layer coating solution Polyvinyl alcohol (PVA105 manufactured by Kuraray Co., Ltd., 2.24 g)
Saponification degree 98.5 mol%, polymerization degree 500, 6 mass% aqueous solution)
Vinyl acetate / vinyl pyrrolidone copolymer 0.0073 g
(BASF-made rubiscol VA64W, 50 mass% aqueous solution)
Polyvinylpyrrolidone (30K, Wako Pure Chemical Industries, Ltd.) 0.0053g
Surfactant 2.15g
(Emalex 710, 1 mass% aqueous solution manufactured by Kao Corporation)
Scale-like synthetic mica 3.75g
(MEB3L manufactured by UNICOO Co., Ltd., average particle size of 1 to 5 μmΦ,
3.4 mass% aqueous dispersion)
Distilled water 10.60g

2. Preparation of plate surface cleaning agent As Examples 1 to 9 and Comparative Examples 1 to 7, the plate surface cleaning agent used for cleaning the plate obtained from various original plates has the composition described in Tables 1 and 2 below (unit: parts by mass). Created according to. “Parts” and “%” represent parts by mass and mass%, respectively, unless otherwise specified.
As an aqueous phase, in 450 parts by mass of pure water, a water-soluble soybean polysaccharide (Fuji Oil Co., Ltd., product name: Soya Five-S-LN: analysis value galactose 43.6%, arabinose 22.5%, galacturonic acid 2 .2%, residual protein 4.7%) or cellogen 5A (carboxymethylcellulose, manufactured by Daiichi Kogyo Kagaku Co., Ltd.) is dissolved in the amount shown in the table, and the acid component is added in the amount shown in the table, with stirring. After dissolution, 20 parts by mass of magnesium nitrate and 5 parts by mass of sodium hydrogen sulfate were added, and 5 parts by weight of 1,2-benzisothiazolin-3-one as a preservative and 40 parts by weight of glycerin as a wetting agent were mixed. The pH was adjusted to 3.0 with sodium hydroxide or citric acid, and water was added thereto to prepare an aqueous phase so that the total amount was 650 parts by weight. Meanwhile, 20 parts by weight of PELEX OT-P (sodium dialkylsulfosuccinate manufactured by Kao Corporation) as an emulsifier and 10 parts by weight of Pionein D-212 (castor oil ether manufactured by Takemoto Yushi Co., Ltd.) Part, 5 parts by weight of Nonion OP-80 (Sorbitan monooleate manufactured by Nippon Oil & Fats Co., Ltd.) was dissolved, and an oil phase was prepared to be 350 parts in total.
Next, the aqueous phase prepared as described above was stirred and heated and adjusted to 35 ° C., and the oil phase was slowly added dropwise to prepare a dispersion, and a milky white emulsion type plate cleaning agent was prepared through a homogenizer.

3. Exposure and Printing The above lithographic printing plate precursors (1) to (3) were exposed using a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser under the conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2400 dpi. After the exposure, using a sapphire needle (having a radius of 0.1 mm at the tip) with a scratch tester (manufactured by Shinto Kagaku Co., Ltd.) on the non-image area of the printing plate at intervals of 20 g in the range of 20 g to 100 g. A scratch was applied under load.
Thereafter, the obtained printing plate was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without developing. After supplying fountain solution and ink using 2% aqueous solution of fountain solution ECOLITY-2 (Fuji Photo Film Co., Ltd.) and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) Printing was performed at a printing speed of 6,000 sheets per hour.
At this time, the number of printing sheets (on-press developability) required until the ink was not transferred to the unexposed portion (non-image portion) of the image recording layer was evaluated.

Further, printing was continued, and it was confirmed that the scratched part was stained on the printed material after 100 sheets were printed. Thereafter, 50 cc of the prepared plate surface cleaning agent was applied to the waste cloth, and the entire surface of the plate was wiped. Then, the plate surface cleaning agent was wiped off with a waste cloth wetted with water. Thereafter, printing for another 100 sheets was continued.
The scratch removal property by the above-mentioned plate surface cleaning agent was evaluated on the printed matter. The degree of contamination was expressed as a load at which scratches could not be seen on the printed material. It is judged that the larger the load value is, the higher the scratch and dirt removal property is.
As the number of printed sheets is further increased, the image recording layer gradually wears and the ink acceptability is lowered, so that the ink density on the printing paper is lowered. Printing durability was evaluated based on the number of printed sheets when the ink density (reflection density) in the solid image area was reduced by 0.1 from the start of printing. The ink density was measured with a Macbeth reflection density meter (manufactured by Gretag Macbeth).
The printing durability is judged to be better when the number of printed sheets is larger.
These results are shown in Tables 1 and 2 together with combinations of the planographic printing plate precursor and the plate surface cleaning agent.

  From the results shown in Table 1 and Table 2, according to the plate surface processing method of the present invention, the performance of removing scratches on the plate surface is high, the image area can be maintained in a good state, and the printing durability is improved. Can be seen to improve.

Claims (6)

  A plate surface treating method for treating a plate surface of a lithographic printing plate with a plate surface cleaning agent, wherein the lithographic printing plate comprises an image recording layer containing an infrared absorber on a support, and a protective layer containing an inorganic layered compound Is a lithographic printing plate obtained by forming an image of a lithographic printing plate precursor having this order, and the plate surface cleaning agent is an emulsion type plate surface cleaning agent containing a film-forming polysaccharide extracted from soybeans. A printing method for a planographic printing plate.   The plate surface treatment method according to claim 1, wherein the infrared absorber is a cyanine dye.   The image forming method includes at least a step of image-exposing the lithographic printing plate precursor using an infrared laser, and a state in which the lithographic printing plate precursor subjected to image exposure is attached to a printing machine and attached to a cylinder of the printing machine. The plate surface processing method according to claim 1, further comprising a step of making a planographic printing plate by removing an unexposed portion of the image recording layer.   The plate surface treatment method according to claim 1, wherein the plate surface cleaning agent further contains an aliphatic hydrocarbon solvent.   The plate surface according to any one of claims 1 to 4, wherein the plate surface cleaning agent further contains at least one compound selected from the group consisting of phosphoric acid, polymerized phosphoric acid, an alkali metal salt thereof, and an organic phosphonic acid. Processing method. The plate surface treating method according to any one of claims 1 to 5, which is used for a lithographic printing plate precursor, wherein the infrared absorber is represented by the general formula (D1).

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. R ¹ and R ² may be bonded to each other to form a ring structure. Ar ¹ and Ar ² each independently represent an optionally substituted aromatic hydrocarbon group Y ¹ and Y ² each independently represent a sulfur atom or a dialkylmethylene having 12 or less carbon atoms R ³ and R ⁴ each independently represents a hydrocarbon group having 20 or less carbon atoms, which may have a substituent, R ⁵ , R ⁶ , R ⁷ and R ⁸ are each Independently represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms, R ⁹ and R ¹⁰ each independently represents an aromatic hydrocarbon group having 6 to 10 carbon atoms which may have a substituent; .R ⁹ and R ¹⁰ represents an alkyl group or a hydrogen atom, 1 to 8 carbon atoms May be bonded together to form a ring structure In this case, the nitrogen atom in the ring structure, an oxygen atom and a heteroatom selected from the group consisting of sulfur atoms which may optionally contain one or more .X. ^- Represents a counter anion, provided that X ⁻ is not necessary when any of R ^{1 to} R ⁸ is substituted with a sulfo group.)