JP2008230208A - On-machine developable original plate of lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-machine developing type original plate of a lithographic printing plate which enables image recording by laser exposure and excels in on-machine developability and plate wear resistance even after an elapse of time after manufacture. <P>SOLUTION: The original plate of the lithographic printing plate has on a substrate an image forming layer which comprises (A) an infrared absorbent, (B) a polymerization initiator, (C) a polymerizable compound, (D) particles of a polymer comprising acrylonitrile as a polymerization constituent and (E) a surfactant. The content of the surfactant is 0.01-1.00 mass% and the image forming layer can be removed by printing ink and/or dampening water. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  Conventionally, the production of a lithographic printing plate has been performed by a system that exposes a lithographic printing plate precursor through a lith film that is an intermediate material. However, with the rapid progress of digitization in the printing field in recent years, the process for producing a lithographic printing plate is changing to a CTP system that directly inputs digital data that has been input to a computer and edited. Furthermore, with the aim of further streamlining processes, development-free lithographic printing plate precursors that can be printed as they are without being developed after exposure have been developed.

  One method of eliminating the processing step is to attach an exposed lithographic printing plate precursor to the plate cylinder of a printing press, and supply dampening water and ink while rotating the plate cylinder to remove unnecessary image forming layers. There is a method called on-press development to remove. That is, the lithographic printing plate precursor is exposed to light and mounted on a printing machine as it is, and the development process is completed in a normal printing process. Such a lithographic printing plate precursor suitable for on-press development has an image forming layer soluble in dampening water or an ink solvent, and is suitable for development on a printing press placed in a bright room. It is necessary to have good light room handling.

  For example, Patent Document 1 describes a lithographic printing plate precursor in which a photosensitive layer in which fine particles of a thermoplastic hydrophobic polymer are dispersed in a hydrophilic binder polymer is provided on a hydrophilic support. In Patent Document 1, a lithographic printing plate precursor is laser-exposed, and thermoplastic hydrophobic polymer particles in a photosensitive layer are coalesced by heat to form an image. It is described that an unexposed portion can be removed (on-press development) with water and / or ink. This lithographic printing plate precursor is also suitable for bright room handling because the photosensitive region is an infrared region.

  Patent Documents 2 to 6 also describe that a printing plate is prepared by on-press development after coalescence of thermoplastic fine particles by heat.

  Patent Document 7 discloses a lithographic printing plate precursor having a heat-sensitive layer containing at least one of thermoplastic polymer fine particles, polymer fine particles having a heat-reactive group, and microcapsules encapsulating a compound having a heat-reactive group. In addition, it is described that the on-press developability is good, the sensitivity is high, and the printing resistance is high.

  Further, Patent Document 8 discloses that printing resistance is improved by an on-press development type heat-sensitive lithographic printing plate precursor having a microcapsule containing a compound having a vinyloxy group, a hydrophilic resin, and an image forming layer containing an acid precursor. Is obtained.

  Further, Patent Document 9 discloses that printing resistance is excellent due to an on-press development type heat-sensitive lithographic printing plate precursor having a microcapsule encapsulating an epoxy group-containing compound, a hydrophilic resin, and an acid precursor. Is obtained.

  Further, in Patent Document 10, it is preferable to use an on-press development type heat-sensitive lithographic printing plate precursor having an image forming layer containing a microcapsule enclosing a compound having a radical polymerizable group, a hydrophilic resin and a heat-sensitive polymerization initiator. It is described that high printing resistance can be obtained.

  In Patent Document 11, fine particles of lipophilic polymer are dispersed in a hydrophilic polymer matrix as a photosensitive layer, and light is converted into heat by light irradiation by a light absorber present in the photosensitive layer. A lithographic printing plate precursor is described in which development is performed by utilizing the fact that the hydrophilicity of the photosensitive layer is lost and the hydrophilicity of the photosensitive layer is lost due to foaming or heat fusing of the oleophilic polymer by the applied heat. ing.

Japanese Patent No. 2938397 JP-A-9-127683 JP-A-9-123387 JP-A-9-123388 JP-A-9-131850 WO99 / 10186 pamphlet JP 2001-293971 A JP 2002-29162 A JP 2002-46361 A JP 2002-137562 A JP 2004-299264 A

  From the practical point of view, the conventional lithographic printing plate precursors still have insufficient on-press developability and printing durability. In particular, the on-press developability was insufficient when the lithographic printing plate precursor was produced and passed over time. Accordingly, an object of the present invention is to provide an on-press development type lithographic printing plate precursor capable of image recording by laser exposure and having excellent on-press developability and printing durability when time passes after production.

The present invention is as follows.
1. The support contains (A) an infrared absorber, (B) a polymerization initiator, (C) a polymerizable compound, (D) polymer particles containing acrylonitrile as a polymerization component, and (E) a surfactant. A lithographic printing plate having an image forming layer, wherein (E) the surfactant content is 0.01 to 1.00% by mass, and the image forming layer can be removed by printing ink and / or fountain solution Original edition.
2. 2. The lithographic printing plate precursor as described in 1 above, wherein the content of the surfactant in the image forming layer is 0.05 to 0.30% by mass.
3. 3. The lithographic printing plate precursor as described in 1 or 2 above, wherein the surfactant is a surfactant containing a fluorine atom.

In the present invention, the above-mentioned problems can be solved by limiting the amount of the surfactant as the image forming layer component and using (D) polymer particles containing acrylonitrile as a polymerization component. Although this mechanism of action is not necessarily clear, it is estimated as follows.
The on-press development type printing plate of the prior art contains a large amount of low molecular weight components such as a polymerizable compound in order to impart on-press developability to remove the image forming layer in the unexposed area with printing ink and / or fountain solution. It was designed. As a result, the film strength of the image forming layer is lowered and development on the machine becomes possible. However, at the same time, mass transfer in the image forming layer during storage over time is promoted, so that the surfactant is localized in a form in which hydrophobic groups are oriented on the surface of the image forming layer, and the surface becomes hydrophobic. This has been found to be a major factor in reducing the wettability of dampening water with respect to the surface of the image forming layer and degrading on-press developability.
The present invention was obtained as a result of research based on the analysis results. The surface hydrophobization over time was reduced by limiting the amount of the surfactant, and the on-press developability was obtained by using (D) acrylonitrile as a polymerization component. It is presumed that good on-press developability and printing durability have become possible even after lapse of time.

  According to the present invention, it is possible to provide an on-press development type lithographic printing plate precursor capable of image recording by laser exposure and having excellent on-press developability and printing durability when time passes after production.

(Image forming layer)
The lithographic printing plate precursor of the present invention comprises, on a support, (A) an infrared absorber, (B) a polymerization initiator, (C) a polymerizable compound, (D) polymer particles containing acrylonitrile as a polymerization component, and ( E) an image forming layer containing a surfactant, and (E) the surfactant content is 0.01 to 1.00% by mass, and the image forming layer is dampened with printing ink and / or dampening. It can be removed with water. In terms of plate making, the lithographic printing plate precursor of the present invention is a negative type on-press development type lithographic printing plate precursor that is polymerized and cured by infrared laser irradiation.
Hereinafter, the image forming layer of the present invention will be described in detail.

<Surfactant>
In the present invention, the image forming layer contains a surfactant in order to promote the on-press developability at the start of printing, particularly in a printing plate stored for a long period of time, and to improve the coated surface state. Conventionally, it was thought that on-press developability was improved by increasing the solid content of the surfactant relative to the solid content of the image forming layer. It was. The present invention is characterized in that the content of the surfactant in the image forming layer is 0.01 to 1.00% by mass. The content of the surfactant is more preferably 0.05 to 0.30% by mass, and most preferably 0.05 to 0.20% by mass.
Surfactant is hydrophobicized on the surface of the image forming layer due to the orientation of the surfactant during long-term storage, and deteriorates on-press developability. However, when the content exceeds 1.00% by mass, the tendency is remarkable. It is not preferable. On the other hand, when the content is less than 0.01% by mass, the surface tension of the coating solution becomes too high, and the uniformity of the image forming layer film is lowered to an unacceptable level.

  Examples of the surfactant used include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.

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

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

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

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

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

  More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. This type of surfactant can particularly remarkably reduce the surface tension of a coating solution used for coating an image forming layer on a substrate. This is because the perfluoro group has a small intermolecular interaction and a large ability to lower the surface tension. In particular, a fluorosurfactant is most preferably used to reduce the surface tension of a coating solution containing a polar solvent having a high dielectric constant, particularly water.

  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.

<Polymer particles containing acrylonitrile as a polymerization component>
The image forming layer of the present invention contains polymer particles containing acrylonitrile as a polymerization component as an essential component. By containing the polymer particles, it is possible to improve the on-press developability without hydrophobizing the surface of the image forming layer over time.
Hydrophilic polymers such as acrylonitrile can improve on-press developability, but at the same time tend to increase the water content of the image forming layer. In such a state, the flexibility of the image forming layer is increased, and mass transfer in the image forming layer is facilitated, so that there is a problem that the surface of the image forming layer is easily hydrophobized.
By making acrylonitrile into particles, hydrophilicity can be localized on the particle surface, so that on-machine developability at the beginning of production can be improved without causing deterioration of on-machine developability during storage over time. . In addition, compared to the case where it is simply added to the image forming layer, the film strength of the image forming layer does not change significantly as a cross-linked or high molecular weight material, and the influence on on-press developability can be reduced. This is also advantageous.
In addition, since acrylonitrile is highly polar, it is known that it has high resistance to UV curable inks containing a large amount of polymerizable compounds, and printing durability when UV ink is used can be imparted.

  The polymer containing acrylonitrile as a polymerization component for forming the particles is preferably a polymer containing acrylonitrile at 30 mol% or more. The acrylonitrile content is more preferably 50 to 90 mol%, most preferably 60 to 80 mol%.

  The component other than acrylonitrile of the polymer is not particularly limited as long as it is a monomer copolymerizable with acrylonitrile, but a monomer having an oxyalkylene chain in the side chain is preferred. As the oxyalkylene chain, polyoxyethylene units and polyoxyethylene / polyoxypropylene units are particularly preferred. Examples of such monomers include polyethylene glycol monomethacrylate, polyoxyethylene / polyoxypropylene monomethacrylate, methoxypolyethylene glycol acrylate, methoxypolyethylene glycol methacrylate, polyethylene glycol acrylate, and polyethylene glycol methacrylate. Of these, polyethylene glycol monomethacrylate is preferred. The number of repeating oxyalkylene units of the polyoxyalkylene is preferably 2 to 120.

  As for content in the copolymer of the monomer which has an oxyalkylene chain, 2-30 mol% is preferable, More preferably, it is 5-20 mol%.

  If necessary, the copolymer containing acrylonitrile of the present invention can be further copolymerized with other monomers. Examples of other monomers include the following.

Styrene monomers such as styrene and α-methylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl methacrylate, tridecyl methacrylate, n-stearyl methacrylate, Cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, t-butyl Methacrylate include methacrylic acid type monomers such as. These acrylic acid bodies are mentioned similarly.
Of these, styrene, methyl methacrylate, and ethyl methacrylate are preferable.

  The mass average molecular weight of the polymer containing acrylonitrile as a polymerization component is preferably 10,000 to 200,000, more preferably 50,000 to 150,000, and still more preferably 50,000 to 100,000.

Although the specific example of the polymer which uses acrylonitrile as a polymerization component below is shown by the monomer component which comprises, this invention is not limited to these.
Polyethylene glycol monomethacrylate / styrene / acrylonitrile = 10/20/70 (mass average molecular weight 80,000), polyethylene glycol monomethacrylate / methyl methacrylate / acrylonitrile = 10/20/70 (mass average molecular weight 80,000), polyethylene glycol monomethacrylate / Examples include methyl methacrylate = 60/40 (mass average molecular weight 60,000), polyethylene glycol monomethacrylate / acrylonitrile = 30/70 (mass average molecular weight 60,000), and the like.

  The above-mentioned method of granulating a polymer containing acrylonitrile as a polymerization component includes a method of forming particles in a polymerization process such as dispersion polymerization, emulsion polymerization, and interfacial polymerization, or a dispersing device such as a homogenizer in a dispersion medium for a binder resin solution. A known method such as a method of removing a solvent that dissolves the binder resin and dissolves the binder resin can be used without limitation.

  A preferable particle diameter is 1 nm to 10 μm, more preferably 10 nm to 1 μm, and still more preferably 10 nm to 500 nm.

  The addition amount of polymer particles containing acrylonitrile as a polymerization component to the image forming layer is preferably 5 to 80%, more preferably 10 to 50%, and still more preferably 10 to 30%.

<Infrared absorber>
The image forming layer of the present invention contains an infrared absorbing agent in order to improve the image forming property with a laser that emits infrared rays of 760 to 1200 nm. The infrared absorber has a function of converting the absorbed infrared ray into heat and a function of being excited by the infrared ray and transferring electrons / energy to a polymerization initiator (radical generator) described later. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

  Examples of the pigment used in the present invention include commercially available pigments, Color Index Handbook, “Latest Pigment Handbook, Japan Pigment Technology Association, 1977”, “Latest Pigment Applied Technology” (CMC Publishing, 1986), “Printing Ink”. The pigments described in “Technology” (CMC Publishing, 1984) and the like can be used. Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, and other polymer-bonded pigments. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used.

  Among these, carbon black is preferably used as a material that efficiently absorbs light in the near infrared to infrared region and is economically excellent. As such carbon black, grafted carbon black having various functional groups and good dispersibility is commercially available. For example, “Carbon Black Handbook 3rd Edition” (edited by Carbon Black Association, 1995) Pp. 167, “Characteristics of Carbon Black and Optimum Formulation and Utilization Technology” (Technical Information Association, 1997), page 111, and the like can be mentioned, all of which are preferably used in the present invention.

These pigments may be used without being surface-treated, or may be used after being subjected to a known surface treatment. Known surface treatment methods include methods of surface coating with resins and waxes, methods of attaching surfactants, methods of bonding reactive substances such as silane coupling agents, epoxy compounds, and polyisocyanates to the pigment surface. It is done. These surface treatment methods are described in "Characteristics and Applications of Metal Soap" (Sachi Shobo), "Latest Pigment Application Technology" (CMC Publishing, 1986), "Printing Ink Technology" (CMC Publishing, 1984). ing.
The particle size of the pigment used in the present invention is preferably in the range of 0.01 to 15 micrometers, and more preferably in the range of 0.01 to 5 micrometers.

As the dye used in the present invention, known and commonly used dyes can be used. For example, “Dye Handbook” (edited by the Society of Synthetic Organic Chemistry, published in 1970), “Color Material Engineering Handbook” (edited by Color Material Association, Asakura Shoten) 1989), “Technology and Market of Industrial Dye” (CMC, published in 1983), “Chemical Handbook Applied Chemistry” (The Chemical Society of Japan, Maruzen Shoten, published in 1986). . More specifically, azo dyes, metal chain salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, indigo dyes, quinoline dyes, nitro dyes, xanthene dyes And dyes such as thiazine dyes, azine dyes, and oxazine dyes.
Examples of dyes that efficiently absorb near infrared rays or infrared rays include, for example, cyanine dyes, methine dyes, naphthoquinone dyes, squarylium dyes, arylbenzo (thio) pyridinium salts, trimethine thiapyrylium salts, pyrylium compounds, pentamethinethio Examples include pyrylium salts and infrared absorbing dyes.

  Among these, as the infrared absorbing agent, a near-infrared absorbing cationic dye represented by the following formula is preferable because the polymerization initiator described later efficiently exhibits a polymerization function.

(In the formula, D ⁺ represents a cationic dye having absorption in the near infrared region, and A ⁻ represents an anion.)

  Examples of cationic dyes having absorption in the near infrared region include cyanine dyes, triarylmethane dyes, aminium dyes, and diimmonium dyes having absorption in the near infrared region. Specific examples of the cationic dye having absorption in the near infrared region include the following.

Examples of anions include halogen anions, ClO ₄ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₆ H ₅ SO ₃ ⁻ , and CH ₃ C ₆ H _4. Examples thereof include SO ₃ ⁻ , HOC ₆ H ₄ SO ₃ ⁻ , ClC ₆ H ₄ SO ₃ ⁻ , and a boron anion represented by the following formula (1). As the boron anion, triphenyl n-butylboron anion and trinaphthyl n-butylboron anion are preferable.

(Wherein R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently an alkyl group, aryl group, alkaryl group, allyl group, aralkyl group, alkenyl group, alkynyl group, alicyclic group, or saturated. Alternatively, it represents an unsaturated heterocyclic group, and at least one of R ⁹ , R ¹⁰ , R ¹¹ and R ¹² is an alkyl group having 1 to 8 carbon atoms.)

Among these, as the cationic dye having absorption in the near infrared region, those represented by the following formula (2) are preferable. Since these dyes have a maximum absorption wavelength of 817 to 822 nm, the obtained lithographic printing plate precursor is suitable for an exposure machine equipped with an existing near infrared semiconductor laser, and has a molar extinction coefficient of 1 × 10 ⁵ or more. Therefore, the sensitivity of the obtained lithographic printing plate precursor becomes good.

(In the formula, X is N (C ₂ H ₅ ) ₂ or N (CH ₃ ) ₂ , Y is N (C ₂ H ₅ ) ₂ , H, or OCH ₃ , and Z ⁻ is the following formula: Any of the anions represented by

  The infrared absorber is used by selecting at least one suitable pigment or dye capable of absorbing a specific wavelength of the light source described later from the above pigments or dyes and adding the selected pigment or dye to the image forming layer.

When a pigment is used as the infrared absorber, the content of the pigment is preferably in the range of 0.5 to 15% by mass, particularly preferably in the range of 1 to 10% by mass with respect to the total solid content of the image forming layer. If the pigment content is less than 0.5% by mass, infrared absorption is insufficient, and if the pigment content exceeds 15% by mass, the amount of heat generated tends to be excessive, which is not preferable.
When a dye is used as the infrared absorber, the content of the dye is preferably in the range of 0.5 to 15% by mass, particularly preferably in the range of 1 to 10% by mass, based on the total solid content of the image forming layer. When the dye content is less than 0.5% by mass, the infrared absorption is insufficient, and when the dye content exceeds 15% by mass, the infrared absorption substantially reaches saturation and the effect of addition is improved. It is not preferable because it tends to be absent.

<Polymerization initiator>
As the polymerization initiator used in the present invention, various photopolymerization initiators known in patent literature, non-patent literature, etc., or a combination system of two or more photopolymerization initiators (photopolymerization), depending on the wavelength of the light source used. The starting system) can be appropriately selected and used. In the present invention, a system using a photopolymerization initiator used alone or two or more photopolymerization initiators is collectively referred to simply as “polymerization initiator”.

As the polymerization initiator, organic boron compounds, onium salts, and triazine compounds are suitable. These polymerization initiators may be used alone or in combination of two or more.
An organoboron compound expresses the function as a polymerization initiator by using together with the above-mentioned infrared absorber. As the organic boron compound, an ammonium salt of a quaternary boron anion represented by the following formula (3) is preferable.

(Wherein R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently an alkyl group, aryl group, alkaryl group, allyl group, aralkyl group, alkenyl group, alkynyl group, alicyclic group, or saturated. Or an unsaturated heterocyclic group, wherein at least one of R ⁹ , R ¹⁰ , R ¹¹ and R ¹² is an alkyl group having 1 to 8 carbon atoms, and R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents a hydrogen atom, an alkyl group, an aryl group, an allyl group, an alkaryl group, an aralkyl group, an alkenyl group, an alkynyl group, an alicyclic group, or a saturated or unsaturated heterocyclic group. )

  Among these, tetra n-butylammonium triphenyl boron, tetra n-butylammonium trinaphthyl boron, tetra n-butylammonium tri (pt-butylphenyl) boron, and tetramethylammonium can be efficiently exhibited. n-butyltriphenylboron, tetramethylammonium n-butyltrinaphthylboron, tetramethylammonium n-octyltriphenylboron, tetramethylammonium n-octyltrinaphthylboron, tetraethylammonium n-butyltriphenylboron, tetraethylammonium n- Butyl trinaphthyl boron, trimethyl hydrogen ammonium n-butyl triphenyl boron, triethyl hydrogen ammonium n-butyl triphenyl ester Containing tetra hydrogensulfate ammonium n- butyl triphenyl borate, tetramethylammonium n- butylboron, etc. tetraethylammonium n- butylboron can be preferably used.

The above-mentioned organoboron compound is used in combination with the above-described infrared absorber (for example, D ⁺ A ⁻ ) to generate radicals (R ·) as shown in the following formula (4) by irradiation with infrared rays, and initiate polymerization. The function as an agent can be expressed (in the formula, Ph represents a phenyl group, R represents an alkyl group having 1 to 8 carbon atoms, and X ⁺ represents an ammonium ion).

  The content of the organoboron compound is preferably in the range of 0.1 to 15% by mass, particularly preferably in the range of 0.5 to 7% by mass, based on the solid content of the image forming layer. When the content of the organic boron compound is less than 0.1% by mass, the polymerization reaction is insufficient, the curing is insufficient, the image portion of the obtained negative lithographic printing plate precursor becomes weak, and the content of the organic boron compound is low. When it exceeds 15% by mass, the polymerization reaction does not occur efficiently. Moreover, you may use together 2 or more types of (B) organoboron compounds as needed.

The onium salt is a salt composed of a cation having one or more onium ion atoms in the molecule and an anion. Examples of the onium ion atom in the onium salt include S ⁺ in sulfonium, I ⁺ in iodonium, N ⁺ in ammonium, and P ⁺ atom in phosphonium. Among these, preferable onium ion atoms include S ⁺ and I ⁺ . Examples of the structure of the onium salt include triphenylsulfonium and derivatives in which an alkyl group or an aryl group is introduced into the benzene ring of the compound, and derivatives in which an alkyl group or an aryl group is introduced into the benzene ring of the compound.

As anions of onium salts, halogen anions, ClO ₄ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₆ H ₅ SO ₃ ⁻ , CH ₃ C Examples thereof include ₆ H ₄ SO ₃ ⁻ , HOC ₆ H ₄ SO ₃ ⁻ , ClC ₆ H ₄ SO ₃ ⁻ , and a boron anion represented by the above formula (1).

As the onium salt, a combination of an onium salt having S ⁺ in the molecule and an onium salt having I ⁺ in the molecule is preferable from the viewpoint of sensitivity and storage stability. Moreover, as an onium salt, the polyvalent onium salt which has a 2 or more onium ion atom in 1 molecule from the point of a sensitivity and storage stability is also preferable. Here, two or more onium ion atoms in the cation are linked by a covalent bond. Among polyvalent onium salts, those having two or more kinds of onium ion atoms in one molecule are preferable, and those having S ⁺ and I ⁺ in one molecule are more preferable. In particular, as the polyvalent onium salt, those represented by the following formulas (5) and (6) are preferable.

The content of the onium salt is preferably in the range of 0.1 to 15% by mass, particularly preferably in the range of 0.5 to 7% by mass, based on the solid content of the image forming layer. If the content of the onium salt is less than 0.1% by mass, the polymerization reaction may be insufficient, and the sensitivity and printing durability of the obtained negative lithographic printing plate precursor may be insufficient. When it exceeds 15% by mass, the developability of the obtained negative type lithographic printing plate precursor becomes poor.
Moreover, you may use 2 or more types of onium salts together as needed. Further, a polyvalent onium salt and a monovalent onium salt may be used in combination.

  The triazine-based compound is a known polymerization initiator used for radical polymerization, and for example, bis (trihalomethyl) -s-triazine can be suitably used as the polymerization initiator. The amount of the triazine compound is usually very small. In addition, when the amount is inappropriate, undesirable results such as blocking of effective light and crystallization in the image forming layer after coating to cause reprecipitation are produced. The content of the triazine compound is preferably used in the range of 0.1 to 15% by mass with respect to the solid content of the image forming layer. Particularly good results are obtained at 0.5 to 7% by mass.

  Moreover, you may add arbitrary promoters, such as mercapto compounds, such as 3-mercaptotriazole, and an amine compound, to a polymerization initiator.

<Polymerizable compound>
The polymerizable compound 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 terminal ethylenically unsaturated bond, preferably two or more. For example, monomers, prepolymers, ie, dimers, trimers and oligomers, or a mixture thereof and a copolymer thereof. Examples of monomers and copolymers thereof include esters of unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.) and aliphatic polyhydric alcohol compounds, unsaturated Examples include amides of carboxylic acids and aliphatic polyvalent amine compounds.

  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 pentaacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, Examples include polyester acrylate oligomers.

  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, dipentaerythritol pentamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p (3-methacryloxy-2-hydroxypropoxy) phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

  Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate. Furthermore, the mixture of the above-mentioned ester monomer can also be mention | raise | lifted.

  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.

  Other examples include polyisocyanate compounds having two or more isocyanate groups in one molecule such as hexamethylene diisocyanate, esters of the above unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds, or the following general Examples thereof include a vinylurethane compound containing two or more polymerizable vinyl groups in one molecule to which a vinyl monomer containing a hydroxyl group represented by the formula (A) or (B) is added.

(Wherein Q ¹ and Q ² independently represent H or CH ₃ , Q ³ represents —CH ₂ OH. A and c are each independently an integer of 1 to 3, and b is 0 or It is an integer from 1 to 2, provided that a + b + c = 4)

  Further, urethane acrylates such as those described in JP-A-51-37193, JP-A-48-64183, JP-B-49-43191, JP-B-52-30490 are described. Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid can be used. Furthermore, the Japan Adhesion Association Vol. 20, no. 7, pages 300 to 308 (1984), those introduced as photocurable monomers and oligomers can also be used.

  Specifically, NK oligo U-4HA, U-4H, U-6HA, U-108A, U-1084A, U-200AX, U-122A, U-340A, U-324A, UA-100 (above, new Nakamura Chemical Co., Ltd.), UA-306H, AI-600, UA-101T, UA-101I, UA-306T, UA-306I (above, manufactured by Kyoeisha Yushi), Art Resin UN-9200A, UN-3320HA, UN-3320HB , UN-3320HC, SH-380G, SH-500, SH-9832 (manufactured by Negami Kogyo Co., Ltd.) and the like.

  The amount of these polymerizable compounds used is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, based on all components of the image forming layer.

In the present invention, the polymerizable compound can be used as a dispersion (microcapsule or microgel) contained in polymer particles.
By using a dispersion, the stickiness on the surface of the image forming layer can be reduced, the problems of adhesion of interleaf paper and fingerprint stains can be improved, and the handleability can be improved. Furthermore, since the physical strength of the image forming layer can be lowered, the on-press developability can be kept good.

As a method for microencapsulating or microgelling the polymerizable compound, known methods can be applied. Here, the microcapsule refers to a core-shell type particle containing a polymerizable compound as a core, and the microgel refers to a particle in which no clear phase separation structure is observed.
For example, microcapsules can be produced by using a method using coacervation as shown in U.S. Pat. Nos. 2,800,457 and 2,800,498, U.S. Pat. Nos. 3,287,154, 38-19574, and 42-446. Method by combined method, method by precipitation of polymer as shown in US Pat. Nos. 3,418,250 and 3,660,304, method using isocyanate polyol wall material as shown in US Pat. No. 3,796,669, method using isocyanate wall material as shown in US Pat. No. 3,914,511 US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802, a method using a urea-formaldehyde-based or urea-formaldehyde-resorcinol-based wall forming material, A method using a wall material such as a mualdehyde resin or hydroxycellulose, an in situ method by monomer polymerization as seen in JP-B-36-9163 and 51-9079, a spray-drying method as seen in British Patent 930422, US Pat. No. 3,111,407 And the like, but not limited to the electrolytic dispersion cooling method found in British Patent Nos. 952807 and 967074.

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. A compound having a thermally reactive group may be introduced into the microcapsule wall.

  The average particle size 1 of the microcapsules is preferably 0.01 to 3.0 μm, more preferably 0.05 to 2.0 μm, and particularly preferably 0.10 to 1.0 μm. Within this range, good resolution and stability over time can be obtained.

  Such microcapsules may or may not be combined with each other by heat. In short, among the microcapsule inclusions, those that ooze out from the capsule surface or outside the microcapsule at the time of application, or those that have entered the microcapsule wall may cause a chemical reaction by heat. You may react with the added hydrophilic resin or the added low molecular weight compound. Alternatively, two or more types of microcapsules may be reacted with each other by providing functional groups that can thermally react with different functional groups. Therefore, it is preferable for image formation that the microcapsules are fused and united by heat, but it is not essential.

  The amount of the microcapsule or microgel added to the image forming layer is preferably 50% by mass or more, and more preferably 70 to 98% by mass in terms of solid content in the case of any fine particles. Within this range, a good image can be formed and good printing durability can be obtained.

  When the microcapsules are contained in the image forming layer of the present invention, a solvent capable of dissolving the inclusion and swelling the wall material can be added to the microcapsule dispersion medium. By such a solvent, diffusion of the encapsulated compound having a thermally reactive group to the outside of the microcapsule is promoted. Such a solvent depends on the microcapsule dispersion medium, the material of the microcapsule wall, the wall thickness, and the inclusion, but can be easily selected from many commercially available solvents. For example, in the case of a water-dispersible microcapsule comprising a crosslinked polyurea or polyurethane wall, alcohols, ethers, acetals, esters, ketones, polyhydric alcohols, amides, amines, fatty acids and the like are preferable.

  Specific compounds include methanol, ethanol, tertiary butanol, n-propanol, tetrahydrofuran, methyl lactate, ethyl lactate, methyl ethyl ketone, propylene glycol monomethyl ether, ethylene glycol diethyl ether, ethylene glycol monomethyl ether, γ-butyl lactone, N, N -Examples include, but are not limited to, dimethylformamide, N, N-dimethylacetamide and the like. Two or more of these solvents may be used. A solvent that does not dissolve in the microcapsule dispersion but dissolves when the solvent is mixed can also be used.

  The addition amount of such a solvent is determined by the combination of materials, but usually 5 to 95% by mass of the coating solution is effective, and a preferable range is 10 to 90% by mass, and a more preferable range is 15 to It is 85 mass%.

<Binder polymer>
A conventionally well-known thing can be used for a binder polymer without a restriction | limiting, The polymer which has film property is preferable. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, methacrylic resins, polystyrene resins, novolac phenolic resins, polyester resins, and synthetic rubbers. And natural rubber.

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

Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, where the ester or amide residue (R of -COOR or CONHR) is 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 represents 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.

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

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

  Further, from the viewpoint of on-press developability of the unexposed portion of the image forming layer, 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, and ammonium. Suitable examples include those having a hydrophilic group such as a group, an amide group, a carboxymethyl group, a sulfonic acid group, and a phosphoric acid group.

  Specific examples include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, hydroxypropylcellulose, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and Salts thereof, polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropyl methacrylate, homopolymers and copolymers of hydroxypropyl acrylate, hydroxy Homopolymers and copolymers of butyl methacrylate, homopolymers of hydroxybutyl acrylate and Copolymers, 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 polymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide, polyvinylpyrrolidone, alcohol soluble nylon, poly of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin Examples include ether.

  As other suitable binders described above, a copolymer of the acrylonitrile and a monomer having a polyalkylene chain in the side chain may be used in a non-particulate form.

  The binder polymer preferably has a mass average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more, preferably 2000 to 250,000. More preferred.

  These binder polymers can be contained in an arbitrary amount in the image forming layer. However, when the amount exceeds 90% by mass, it does not give favorable results in terms of image strength formed using the layer. Therefore, it is preferably 1 to 50% by mass, more preferably 5 to 30% by mass.

  The use ratio of the polymerizable compound and the binder polymer is preferably 1/9 to 9/1 by mass ratio, more preferably 2/8 to 8/2, most preferably 3 /. 7-7 / 3.

<Other additives>
In the image forming layer of the present invention, it is further desirable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the polymerizable compound during formation or storage of the image forming layer. Preferred thermal polymerization inhibitors 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-nitrosophenylhydroxylamine cerium salt, N-nitrosophenylhydroxylamine aluminum salt, and the like. The addition amount of this type of thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass of the total components of the image forming layer.

  If necessary, 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 surface of the photopolymerizable image forming layer during the drying process after coating. It may be unevenly distributed. The addition amount of the higher fatty acid derivative is preferably 0.5 to 10% by mass of the total components of the image forming layer.

  A colorant may be added for the purpose of coloring the image forming layer. Examples of the colorant include phthalocyanine pigments (CI Pigment Blue 15: 3, 15: 4, 15: 6, etc.), azo pigments, pigments such as carbon black and titanium oxide, ethyl violet, crystal violet, There are azo dyes, anthraquinone dyes, and cyanine dyes. The addition amount of the dye and the pigment is preferably about 0.5% by mass to about 5% by mass of the total components of the image forming layer.

Furthermore, an additive such as an inorganic filler or a plasticizer such as dioctyl phthalate, dimethyl phthalate, or tricresyl phosphate may be added to improve the physical properties of the cured film obtained from the image forming layer. As the inorganic filler, silica particles are preferable, and modified silica particles whose surface characteristics are modified are particularly preferable. Silica particles are those commonly used in the technical field and contain silicon dioxide (SiO ₂ ) as a main component. The particle size of the silica particles is usually 1 nm to 1000 nm, preferably 1 nm to 500 nm, more preferably 1 nm to 100 nm. Silica particles are commercially available. For example, Snowtex OL (particle size 45 nm silica 20% by mass colloidal aqueous solution) and MEK-ST (particle size 10-20 nm silica 30% by mass colloidal methyl ethyl ketone solution manufactured by Nissan Chemical Industries, Ltd.) ) Nippon Aerosil Co., Ltd. product AEROSIL130 (particle diameter 16 nm silica), Mizusawa Chemical Co., Ltd. product Mizukasil P-527U (particle diameter 60 nm silica), etc. are mentioned.
Silica particles include forms such as fumed silica, precipitated silica, and colloidal silica. Among these, the use of colloidal silica is preferable.

The silica particles are preferably used as modified silica particles by modifying their surfaces with an organic compound having at least one ethylenically unsaturated group, at least one hydrophilic site and at least one silyloxy group. Reactivity with an ethylenically unsaturated group and a polymerizable compound is imparted, and a silyloxy group imparts binding properties with silica particles. The ethylenically unsaturated group and the silyloxy group are preferably located at both ends of the molecular chain of the organic compound. In this case, the hydrophilic portion exists between the ethylenically unsaturated group and the silyloxy group. The hydrophilic portion is not particularly limited, but is preferably a polyoxyalkylene chain, and may be any of a polyethylene chain, a polypropylene chain, or a polyethylene-polyoxypropylene chain. Is preferred.
Specifically, the organic compound preferably has the following formula.

_{CH 2 = CH-COO- (CH} 2 CH 2 O) m - (CH 2 CH (CH 3) O) n -CO-X- (CH 2) o - (CHY) p - (CH 2) q -Si (OR) ₃

[Wherein, R is an alkyl group of _C 1 -C _6, preferably methyl or ethyl, X _{is, -CH 2 -, - O -} , - S-, and selected from -NZ- a divalent organic group (Z represents an alkyl group of H or _C 1 -C _6), preferably H, Y _is an alkyl group or a halogen atom C 1 -C _6, preferably Is a methyl group or a fluorine atom,
m is an integer from 0 to 100, preferably an integer from 1 to 50;
n is an integer of 0 to 100, preferably an integer of 0 to 20,
However, m + n is 1 or more,
o is an integer of 0 to 10, preferably an integer of 1 to 10,
p is an integer of 0 to 5, preferably an integer of 0 to 2,
q is an integer of 0 to 10, preferably an integer of 1 to 10,
However, o + q is 1 or more, preferably 2 or more.]

When the organic compound of the above formula is reacted with silica particles, the silyloxy group (—Si (OR) ₃ ) reacts with a hydroxyl group on the silica surface to form a covalent bond, so that the surface of the silica particle is modified. The ethylenically unsaturated group bonded to the silica surface becomes a reaction site with the polymerizable compound.

The surface modification of the silica particles with the organic compound can be performed by a method commonly used in the technical field such as bringing both into contact with each other for a predetermined time. The modification rate on the surface of the silica particles is usually in the range of 50 to 99%, preferably 80 to 99%. The modification rate on the surface of the silica particles can be controlled by adjusting the mass ratio between the silica particles and the organic compound.
Since the organic compound has at least one ethylenically unsaturated group, the image forming layer containing the silica particles modified with the organic compound and the polymerizable compound is further improved in adhesion to the underlayer. Therefore, a lithographic printing plate precursor provided with the image forming layer on a support through an underlayer is exposed to the support and the image formed even if the polymerizable compound in the image forming layer is crosslinked by the exposure and the image forming layer contracts. Good integrity with the layer can be maintained.

  The image forming layer in the lithographic printing plate precursor according to the present invention is obtained by dissolving the photosensitive composition containing the polymerizable compound in various organic solvents and coating it on a hydrophilic underlayer such as a polyvinylphosphonic acid treatment. Can do.

  Solvents that can be used here include acetone, methyl ethyl ketone, cyclohexane, ethyl acetate, ethylene dichloride, tetrahydrofuran, dimethyl ether, diethyl ether, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, Propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 3-methoxypropanol, methoxymethoxyethanol, di Tylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, Examples include methyl lactate, ethyl lactate, methanol, ethanol, propanol, butanol, and water. These solvents can be used alone or in combination. In addition, 1-50 mass% is suitable for solid content concentration in a coating solution.

The coverage of the image-forming layer of the lithographic printing plate precursor of the present invention is in the range of 0.1 to 10 g / ^{m 2} in weight after coating and drying are suitable, more preferably be 0.3 to 5 g / ^{m 2} , more preferably from 0.5 to 3 g / ^{m 2.}

[Protective layer]
In the lithographic printing plate precursor according to the invention, a protective layer can be provided on the image forming layer. The protective layer prevents exposure of low molecular weight compounds such as oxygen and basic substances present in the air that inhibit the polymerization reaction in the image forming layer to the image forming layer and facilitates exposure conditions in the air. . The properties desired for such a protective layer are low permeability of low-molecular compounds such as oxygen, furthermore, good transparency of irradiation light used for exposure, and excellent adhesion with the image forming layer, And it can be easily removed during development.

  Examples of the material for the protective layer include water-soluble polymer compounds having relatively excellent crystallinity. Specific examples include polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, and polyacrylic acid. is there. Of these, the use of polyvinyl alcohol as the main component gives the best results for basic properties such as oxygen barrier properties and development removability. The polyvinyl alcohol used for the protective layer may be partially substituted with an ester, an ether and an acetal as long as it contains an unsubstituted vinyl alcohol unit for having the necessary oxygen barrier properties and water solubility. Similarly, some of them may have other copolymer components.

  Specific examples of polyvinyl alcohol (PVA) include those that are hydrolyzed by 71 to 100 mol% and have a molecular weight in the range of 300 to 2400. Specifically, Kuraray Co., Ltd. PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA- 420, PVA-613, PVA-L8 and the like.

  The components of the protective layer (selection of PVA type, use of additives, etc.), coating amount, etc. are selected in consideration of fogging, adhesion, and scratch resistance in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of the PVA used (the higher the content of unsubstituted vinyl alcohol units in the protective layer), the thicker the film thickness, the higher the oxygen barrier property, which is advantageous in terms of sensitivity. . However, if the oxygen barrier property is extremely increased, problems such as unnecessary polymerization reaction during production and storage, and unnecessary fogging and image line weighting during exposure occur. In addition, adhesion to the image area and scratch resistance are extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on an oleophilic image forming layer, film peeling due to insufficient adhesion tends to occur, and the peeled portion causes defects such as poor film hardening due to inhibition of oxygen polymerization. As a method for improving the adhesion between the two layers, there is mainly a method in which 20 to 60% by mass of an acrylic emulsion or a water-insoluble vinylpyrrolidone-vinyl acetate copolymer is mixed in a hydrophilic polymer composed of polyvinyl alcohol. It is done.

[Support]
As the support for the lithographic printing plate precursor according to the invention, any material can be used as long as the surface is hydrophilic. However, a dimensionally stable plate-like material is preferable, for example, paper, plastic (for example, polyethylene, polypropylene, Paper laminated with polystyrene, etc., and also metals such as aluminum (including aluminum alloys), zinc, copper, etc. or alloys thereof (eg silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, Nickel alloy) plate, and further, for example, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose butyrate acetate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc. Plastic fill The above described metal or alloys laminated or deposited paper or plastic films. Of these supports, the aluminum plate is particularly preferred because it is dimensionally remarkably stable and inexpensive. Further, a composite sheet in which an aluminum sheet is bonded on a polyethylene terephthalate film as described in Japanese Patent Publication No. 48-18327 is also preferable. Usually, the thickness is about 0.05 mm to 1 mm.

  In the case of a support having a surface of metal, particularly aluminum, surface treatment such as graining treatment described later, immersion treatment in an aqueous solution of sodium silicate, potassium fluoride zirconate, phosphate, etc., or anodization treatment may be performed. It is preferable that it is made.

<Graining process>
Examples of the graining method include mechanical graining, chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. Furthermore, electrochemical graining method that electrochemically grains in hydrochloric acid or nitric acid electrolyte solution, and wire brush grain method that scratches aluminum surface with metal wire, and ball grain method that graines aluminum surface with polishing ball and abrasive. Further, a mechanical graining method such as a brush grain method in which the surface is grained with a nylon brush and an abrasive can be used, and the above graining methods can be used alone or in combination. Among them, the method of making the surface roughness usefully used in the present invention is an electrochemical method of graining chemically in hydrochloric acid or nitric acid electrolyte, and a suitable current density is in the range of 100 to 400 C / dm ² . It is. More specifically, electrolysis is performed in an electrolytic solution containing 0.1 to 50% by mass of hydrochloric acid or nitric acid at a temperature of 20 to 100 ° C., a time of 1 second to 30 minutes, and a current density of 100 to 400 C / dm ^2. It is preferable.

The grained aluminum support is chemically etched with acid or alkali. When an acid is used as an etching agent, it takes time to destroy the fine structure, which is disadvantageous when the present invention is applied industrially, but it can be improved by using an alkali as the etching agent. Examples of suitable alkali agents include caustic soda, sodium carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide and the like. Preferred ranges of concentration and temperature are 1 to 50% by mass, respectively. The conditions are 20 to 100 ° C. and the amount of aluminum dissolved is preferably 5 to 20 g / m ³ .

  After etching, pickling is performed to remove dirt (smut) remaining on the surface. Examples of the acid used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid. In particular, as a method for removing smut after the electrochemical surface roughening treatment, contact with 15 to 65 mass% sulfuric acid at a temperature of 50 to 90 ° C. as described in JP-A-53-12739 is preferable. And the alkali etching method described in Japanese Patent Publication No. 48-28123. In addition, the surface roughness (Ra) of the aluminum support preferable in the present invention is 0.3 to 0.7 μm.

<Anodizing treatment>
The aluminum support treated as described above is preferably further subjected to an anodizing treatment. The anodizing treatment can be performed by a method conventionally performed in the technical field. Specifically, sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc., or a combination of two or more of these, and when direct current or alternating current is applied to aluminum in an aqueous solution or non-aqueous solution, aluminum is supported. An anodized film can be formed on the body surface. The conditions of the anodizing treatment cannot be determined unconditionally because they vary depending on the electrolytic solution used. In general, the concentration of the electrolytic solution is 1 to 80% by mass, the liquid temperature is 5 to 70 ° C., and the current density is 0. The range of 5 to 60 amperes / dm ² , voltage of 1 to 100 V, and electrolysis time of 10 to 100 seconds is appropriate.
Among these anodizing treatments, a method of anodizing at a high current density in sulfuric acid, particularly described in British Patent 1,412,768, and US Pat. No. 3,511,661. A method of anodizing phosphoric acid described in the specification as an electrolytic bath is preferable.
In the present invention, the anodized film is preferably from ^{1~10g / m 2, 1g / m} 2 less than the plate to easily enter the wound to be, requires significant power production exceeds 10 g / ^{m 2} It is economically disadvantageous. Preferably, it is 1.5-7 g / m < ² >, More preferably, it is 2-5 g / m < ² >.

  Furthermore, in the present invention, the support may be subjected to a sealing treatment after the graining treatment and the anodic oxidation. Such sealing treatment is performed by immersing the substrate in a hot aqueous solution containing hot water and an inorganic salt or an organic salt, a steam bath, or the like.

  Further, in the present invention, the support is preferably subjected to a treatment with an alkali metal silicate after the graining treatment and anodizing. Thereby, the adhesiveness between a base layer and a support body further improves. The treatment with an alkali metal silicate as used herein refers to immersing the support in an alkali metal silicate aqueous solution for a predetermined time. In the treatment with the alkali metal silicate aqueous solution, the preferable treatment time is 1 second to 2 minutes, the temperature of the preferred alkali metal silicate aqueous solution is 40 to 90 ° C., and the preferred concentration of the alkali metal silicate aqueous solution is 1 g / l to 50 g / l. Examples of the alkali metal silicate include sodium silicate, potassium silicate, and lithium silicate.

[Plate making]
The above-described planographic printing plate precursor of the present invention is preferably imagewise exposed with a laser. Although the 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 μs. Moreover, it is preferable that irradiation energy amount is 10-300 mJ / cm < ² >.

  In the present invention, the removal of the unexposed image forming layer of the lithographic printing plate precursor can be carried out on a printing machine, but can also be carried out using a developing machine. Examples of the aqueous component used for the removal include liquids in which various compounds are dissolved or dispersed in water. As various compounds dissolved or dispersed in water, polar solvents such as alcohols, surfactants, organic acids and salts thereof, inorganic acids and salts thereof are preferably used from the viewpoint of on-press developability.

Examples of the alcohol include methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol, ethylene glycol monomethyl ether, 2-ethoxyethanol, diethylene glycol monoethyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, propylene glycol, Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono n-propyl ether, propylene glycol mono n-butyl ether, dipropylene glycol monomethyl ether, octanediol, polyethylene glycol monomethyl ether, polypropylene glycol, tetraethylene glycol, glyce Emissions, and the like.
Of these, isopropanol, benzyl alcohol, propylene glycol monomethyl ether, propylene glycol mono n-butyl ether, octanediol, and glycerin are particularly preferably used.

  As a ratio of the alcohol contained in the said aqueous component, 0.01-10 mass% is preferable, 0.1-5 mass% is more preferable, 0.5-3 mass% is especially preferable. Within this range, the on-press developability can be favorably promoted without causing damage to the exposed portion of the image forming layer.

  When an aqueous solution containing the surfactant is used as the aqueous component, generation of bubbles between the blanket cleaning member and the blanket surface, generation of bubbles in a tank containing the aqueous component, the blanket From the viewpoint of avoiding various problems due to foaming such as load on the pump due to mixing of foam into the liquid feed pump for supplying the aqueous component to the cleaning member, among the aqueous components, Less is preferred.

  The surfactant is not particularly limited, and examples thereof include nonionic surfactants and anionic surfactants.

Examples of the nonionic surfactant include polyethylene glycol type higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, higher alkylamine ethylene oxide adduct, Fatty acid amide ethylene oxide adduct, oil and fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, dimethylsiloxane-ethylene oxide block copolymer, dimethylsiloxane- (propylene oxide-ethylene oxide) block copolymer, etc., and polyhydric alcohol type glycerol Fatty acid ester, pentaerythritol fatty acid ester, sorbitol and sorbitan fatty acid ester , Fatty acid esters of sucrose, alkyl ethers of polyhydric alcohols, fatty acid amides of alkanolamines. These nonionic surfactants may be used alone or in combination of two or more.

  The nonionic surfactant has an HLB (Hydrophile-Lipophile Balance) value of preferably 6 to 15 from the viewpoint of improving the stable solubility or turbidity in water and the on-press developability. More preferably, it is ~ 13, and it is especially preferable that it is 6-11.

  Examples of the anionic surfactant include fatty acid salts, abietic acid salts, hydroxyalkanesulfonic acid salts, alkanesulfonic acid salts, dialkylsulfosuccinic acid salts, linear alkylbenzenesulfonic acid salts, branched alkylbenzenesulfonic acid salts, alkylnaphthalenesulfonic acid Salts, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium, N-alkyl sulfosuccinic acid monoamide disodium salts, petroleum sulfonates, sulfated castor Oil, sulfated beef tallow oil, fatty acid alkyl ester sulfate ester salt, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, fatty acid monoglyceride sulfate Ester 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.

More specifically, for example, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium stearate, potassium oleate, sodium dioctylsulfosuccinate, polyoxy Examples include sodium ethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sodium dialkylsulfosuccinate, sodium stearate, sodium oleate, sodium tert-octylphenoxyethoxypolyethoxyethyl sulfate, and the like. .
Of these, dialkylsulfosuccinates, alkylsulfate esters and alkylnaphthalenesulfonates are particularly preferably used.

  The ratio of the surfactant contained in the aqueous component is preferably 0.01 to 0.20% by mass, more preferably 0.02 to 0.18% by mass, and 0.04 to 0.15% by mass. Particularly preferred. Within this range, the on-press developability can be favorably promoted without causing deterioration of the stability of the aqueous component and problems due to foaming.

  For the purpose of further foam suppression, a known antifoaming agent can be added to the aqueous component. Especially as said antifoamer, a silicone type antifoamer is preferable. Further, in the aqueous component, an alkali agent (for example, sodium carbonate, diethanolamine, sodium hydroxide, etc.) and a preservative (for example, benzoic acid and its derivatives, sodium dehydroacetate, 3-isothiazolone compound, 2-bromo-2--2-hydroxy-2-hydroxy-2-hydroxy-2-hydroxy-2-amino-2-phenyl ester) Nitro-1,3-propanediol, 2-pyridinethiol-1-oxide sodium salt, etc.) can also be added.

  Examples of the water-soluble polymer compound used in the aqueous component of the present invention include soybean polysaccharide, modified starch, gum arabic, dextrin, fibrin derivatives (eg, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.) and modified products thereof, pullulan. , Polyvinyl alcohol and its derivatives, polyvinyl pyrrolidone, polyacrylamide and acrylamide copolymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, styrene / maleic anhydride copolymer, etc. It is done.

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

  As the modified starch, known ones can be used. Starch such as corn, potato, tapioca, rice, wheat is decomposed with acid or enzyme in the range of 5 to 30 glucose residues per molecule, and further in alkali. It can be made by a method of adding oxypropylene or the like.

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

  Various existing fountain solutions may be used as the aqueous component containing the various additives as described above.

  The amount of the aqueous component supplied to the lithographic printing plate precursor is preferably 0.1 to 5 μm on the lithographic printing plate precursor although it depends on the type of the aqueous component. More preferably, it is 0.5-3 micrometers.

The temperature of the aqueous component as described above can be used at any temperature, but is preferably 10 to 50 ° C.
The pH of the aqueous component as described above is preferably 2.0 to 10.0, more preferably 3.0 to 9.0, and most preferably 3.5 to 8.5.

  In the lithographic printing method of the present invention, as described above, the lithographic printing plate precursor of the present invention can be imagewise exposed with a laser and then subjected to development treatment to print. It is preferable to print by supplying the oil-based ink and the aqueous component without going through the development processing step. Specifically, after exposing the lithographic printing plate precursor with an infrared laser, mounting it on a printing machine without passing through the development process, printing the lithographic printing plate precursor on the printing machine, Examples include a method of printing with an infrared laser and printing without going through a development process.

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

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

[Examples 1 to 7 and Comparative Examples 1 and 2]
1. Preparation of lithographic printing plate precursor The components listed in Table 1 or 2 below were added to each of the substrates that had been subjected to polyvinyl phosphonic acid treatment on an aluminum substrate that had been electrolytically roughened and anodized with phosphonic acid, in a solvent (n-propanol / water / 2). -A solution dissolved in butanone = 76/20/4 (mass ratio) so as to have a solid content concentration of 12% was applied using a wire bar so that the dry coating amount became 1.5 g / m ² , and 100 ° C. For 90 seconds.

* 1: A polymerizable compound obtained by reacting DESMODUR N100 (aliphatic polyisocyanate resin containing hexamethylene diisocyanate: manufactured by Bayer) with hydroxyethyl acrylate and pentaerythritol triacrylate. 2-Butanone 80 mass% solution * 2: Polyethylene glycol methyl ether methacrylate / styrene / acrylonitryl = 10/20/70 copolymer 21 mass% n-propanol / water = 80/20 mixed solvent dispersion * 3: Trimethylolpropane tetraacrylate (Sartomer)
* 4: 2% by mass aqueous solution * 5: 75% by mass solution of iodonium (4-methoxyphenyl [4- (2-methylpropyl) phenyl] hexafluorophosphoric acid) in propylene carbonate (manufactured by Ciba Specialty Chemicals)
* 6: Mercapto-3-triazole-1H, 2, 4 available from PCAS (France)
* 7: 25% by mass solution of modified dimethylpolysiloxane copolymer in xylene / methoxypropylacetic acid solution (by BYK Chemie)

2. Evaluation of lithographic printing plate precursor (1) Uniformity of image forming layer coating After the lithographic printing plate precursor was produced, the surface of the lithographic printing plate precursor was visually observed. The results are shown in Table 2.

(2) Wettability of the image forming layer surface to dampening water The wettability of the image forming layer surface to the dampening water can be evaluated by an aerial water droplet contact angle using dampening water. The contact angle measurement of the water droplets on the image forming layer of the obtained lithographic printing plate was carried out by the following method.
DropMaster 500 (manufactured by Kyowa Interface Science Co., Ltd.) as the measuring device, and 3% by volume aqueous solution of ECOLITY-2 (manufactured by FUJIFILM Corporation) was used as the dampening water to be dripped. The value of the contact angle after another 10 seconds was used as an index. Moreover, the measurement was performed 3 times and the average value was adopted. The results are shown in Table 2.

(3) On-machine developability Exposure was performed under the conditions of an output of 17 W, an external drum rotational speed of 133 rpm (exposure amount of 300 mJ / cm ² ), and a resolution of 2400 dpi using a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser.
The exposed exposed original plate was attached to a cylinder of a Sprint 25 printing machine manufactured by Komori Corporation without developing. Using 3% by volume aqueous solution of ECOLYTY-2 fountain solution (Fuji Film Co., Ltd.) and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.), After feeding, printing was performed at a printing speed of 8000 sheets per hour, and the number of printed sheets required to obtain a good printed matter was evaluated as on-press developability. The results are shown in Table 2.

(4) Printing durability If printing is continued as it is after development on the machine, the image forming layer in the image area is worn and the ink acceptability is lowered, so that the ink density (reflection density) on the printing paper is lowered. Printing durability was evaluated based on the number of printed sheets when the ink density was reduced by 0.1 from the start of printing. The results are shown in Table 2.

  As can be seen from these results, the lithographic printing plate precursor according to the present invention can obtain good printing durability and on-press developability even after aging after production without impairing the uniformity of the image forming layer film. I understand that I can do it.

Claims (3)

  The support contains (A) an infrared absorber, (B) a polymerization initiator, (C) a polymerizable compound, (D) polymer particles containing acrylonitrile as a polymerization component, and (E) a surfactant. A lithographic printing plate having an image forming layer, wherein (E) the surfactant content is 0.01 to 1.00% by mass, and the image forming layer can be removed by printing ink and / or fountain solution Original edition.   The lithographic printing plate precursor according to claim 1, wherein the content of the surfactant in the image forming layer is 0.05 to 0.30% by mass.   The lithographic printing plate precursor as claimed in claim 1 or 2, wherein the surfactant is a surfactant containing a fluorine atom.