JP5172097B2 - Planographic printing plate precursor and method for producing lithographic printing plate precursor - Google Patents

Description

  The present invention relates to a so-called lithographic printing plate precursor capable of direct plate making by scanning with a laser beam based on a digital signal from a computer or the like, and in particular, ink inking property (ink acceptability) during printing. The present invention relates to a lithographic printing plate precursor that gives a lithographic printing plate that is stable and excellent in printing durability, a production method thereof, and a lithographic printing method using the lithographic printing plate precursor.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area, and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Usually, the lithographic printing plate precursor is exposed through an original image such as a lithographic film, and then the portion that becomes the image portion of the image recording layer is left, and the other unnecessary image recording layer is formed with an alkaline developer or organic A lithographic printing plate is obtained by dissolving and removing with a solvent and making a plate by a method in which the surface of the hydrophilic support is exposed to form a non-image area.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing an unnecessary image recording layer with a developer or the like is necessary after exposure. However, such additional wet processing is unnecessary or Simplification is cited as one of the issues. In particular, in recent years, disposal of waste liquids discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and therefore, the demand for solving the above-mentioned problems has become stronger.

On the other hand, as a simple plate making method, an image recording layer that can remove an unnecessary portion of a lithographic printing plate precursor in a normal printing process is used. There has been proposed a method called on-press development in which a lithographic printing plate is obtained by removing the film.
As a specific method of on-press development, for example, a method using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in a dampening water, an ink solvent or an emulsion of a dampening water and an ink, Method of mechanically removing the image recording layer by contact with rollers or blankets of a printing press, cohesion of the image recording layer or adhesion between the image recording layer and the support by penetration of dampening water, ink solvent, etc. And a method of mechanically removing the image-recording layer by contact with rollers or a blanket cylinder.
In the present invention, unless otherwise specified, the “development process step” refers to using a device other than a printing press (usually an automatic developing machine) and bringing a liquid (usually an alkaline developer) into contact therewith. Refers to the process of removing the unexposed portion of the image recording layer of the lithographic printing plate precursor and exposing the surface of the hydrophilic support, and “on-press development” refers to a liquid (usually printing ink) using a printing press. And / or a fountain solution) is a method and a process for removing the unexposed portion of the image recording layer of the lithographic printing plate precursor and exposing the hydrophilic support surface.

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

  As described above, in recent years, simplification, drying, and no processing of plate making operations have become more desirable than ever in terms of both consideration for the global environment and adaptation to digitalization. It is coming.

  As such a lithographic printing plate precursor, for example, a lithographic printing plate precursor in which an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is provided on a hydrophilic support is known ( For example, see Patent Document 1.) The lithographic printing plate precursor is exposed to an infrared laser to form an image by fusing the hydrophobic thermoplastic polymer particles by heat, and is then mounted on a cylinder of a printing machine, fountain solution and / or On-press development is possible by supplying ink.

  However, the method for forming an image by merging the polymer fine particles by simple thermal fusion as described above exhibits good on-press developability, but the image strength is extremely weak and the printing durability is insufficient.

In order to improve the printing durability of such an on-press developable lithographic printing plate precursor, a thermosensitive layer comprising a microcapsule containing a compound having a functional group that reacts with heat on a hydrophilic support is provided. There has been proposed a lithographic printing plate precursor provided with an infrared absorber in a heat-sensitive layer or an adjacent layer (see Patent Document 2 and Patent Document 3).
However, this technique is still insufficient from the viewpoint of practical printing durability.

As another technique for improving printing durability, a lithographic printing plate precursor capable of on-press development, which is provided with a photosensitive layer containing an infrared absorber, a radical polymerization initiator and a polymerizable compound on a support, is known. (See Patent Document 4). Furthermore, Patent Document 5 discloses (a) a water-soluble or water-dispersible polymer, (b) a monomer or oligomer having a photopolymerizable ethylenically unsaturated double bond, and (c) on an aluminum support. ) A lithographic printing plate precursor is described which uses a photosensitive composition containing a photopolymerization initiation system having an absorption maximum in the ultraviolet region and can be developed on-machine after exposure.
The method using a reaction such as a polymerization reaction as described above can improve the image strength because the chemical bond density of the image portion is higher than that of the image portion formed by thermal fusion of polymer fine particles. However, it is still insufficient in terms of both on-press developability, fine line reproducibility and printing durability, and improvements are desired.

In the planographic printing plate precursor using radical polymerization reaction, a protective layer (overcoat layer) is provided on the image recording layer to prevent scratches, block oxygen, and prevent ablation during high-intensity laser exposure. It has been. Conventionally, a layer mainly composed of a water-soluble polymer compound has been used for the protective layer, but on-machine development performance, fine line reproduction performance, printing durability, ink landing performance and on-machine development running performance (continuously The situation is insufficient to satisfy all the suitability of mixing the on-machine development removal product into the fountain solution when repeated on-press development and printing are performed, and further improvement is desired.
Japanese Patent No. 2938397 JP 2001-277740 A JP 2001-277742 A JP 2002-287334 A JP 2000-39711 A

  The present invention is to remedy the drawbacks of the prior art. That is, an object of the present invention is to provide a lithographic printing plate precursor capable of recording an image with a laser beam, having good on-press developability, and having excellent inking properties and printing durability, and a method for producing the same. It is in. Another object of the present invention is to provide a lithographic printing method which has good on-press developability and is excellent in thickness setting and printing durability.

As a result of various studies to solve the above problems, the present inventor has found that the problem can be solved by effectively using an organic cation.
The present invention is as follows.
[1]
An image recording layer containing (A) an actinic ray absorber, (B) a polymerization initiator, and (C) a polymerizable compound on the support, and removable with dampening water and / or ink, and a particle size of 1 μm A lithographic printing plate precursor having the above-described protective layer containing an inorganic layered compound in this order, wherein the inorganic layered compound contains an organic cation.
[2]
An image recording layer containing (A) an actinic ray absorber, (B) a polymerization initiator, and (C) a polymerizable compound and removable with dampening water and / or ink is formed on the support. A method for producing a lithographic printing plate precursor comprising applying an aqueous solution containing an inorganic stratiform compound having a particle size of 1 μm or more and an organic cationic compound on a recording layer to form a protective layer.
The present invention is the invention according to the above [1] or [2], but is described below including other matters for reference.

1. A lithographic printing plate precursor having an image recording layer and a protective layer containing an inorganic stratiform compound in this order on a support, wherein the inorganic stratiform compound contains an organic cation.
2. 2. The lithographic printing plate precursor as described in 1 above, wherein the particle size of the inorganic stratiform compound is 1 μm or more.
3. 3. The lithographic printing plate precursor as described in 1 or 2 above, wherein the image recording layer comprises (A) an actinic ray absorber, (B) a polymerization initiator, and (C) a polymerizable compound.
4). 4. The lithographic printing plate precursor as described in any one of 1 to 3 above, wherein the image recording layer can be removed with dampening water and / or ink.
5. An image recording layer is formed on a support, and a protective layer is formed on the image recording layer by applying an aqueous solution containing an inorganic stratiform compound and an organic cationic compound. Production method.
6). In a lithographic printing plate precursor having an image recording layer capable of forming an image by supplying an oil-based ink and an aqueous component on a support and removing an unexposed portion on a support after exposure, and a protective layer thereon A lithographic printing plate precursor comprising a phosphonium compound represented by the following general formula (I) in the image recording layer and / or protective layer.

In the formula, R _{1 to} R ₄ each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylthio group, a heterocyclic group, or a hydrogen atom. At least two of R _{1 to} R ₄ may be bonded to form a ring. X ⁻ represents an anion.

7). In the general formula (I), the anion represented by X ⁻ is Cl ⁻ , Br ⁻ , or I ⁻ , or an alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aryloxy group 7. The lithographic printing plate precursor as described in 6 above, which is an organic carboxylate anion or organic sulfonate anion having a substituent selected from an alkylthio group and a heterocyclic group.
8). 8. The above 6 or 7, wherein the image recording layer contains (A1) an infrared absorber, (B) a polymerization initiator, (C) a polymerizable compound, and (D) a binder polymer. Lithographic printing plate precursor.
9. 9. The lithographic printing plate precursor as described in any one of 6 to 8, wherein the protective layer contains an inorganic stratiform compound.
10. In the lithographic printing method of printing after removing the unexposed portion of the image recording layer by supplying oil-based ink and fountain solution on a printing machine after exposure, the fountain solution is represented by the above general formula (I). A lithographic printing method comprising a fountain solution containing a phosphonium compound.

  In general, phosphonium compounds have long been known as photosensitive acid generators, for example, in JP-A No. 50-158698. Further, it is known from JP-A-5-112085 to add a phosphonium compound to dampening water so as to function as a protective agent for the image area in the PS plate. However, in these on-press development type plate material systems such as the present invention, while maintaining the penetration of dampening water during on-press development, the removal of the protective layer mainly composed of the hydrophilic resin in the exposed portion and There is no disclosure or suggestion for solving the problem of suppressing re-adsorption.

According to the present invention, there are provided a lithographic printing plate precursor capable of recording an image with a laser beam, having good on-machine developability, and excellent in the walling property and printing durability, and a method for producing the lithographic printing plate precursor. it can.
In addition, according to the present invention, by using a lithographic printing plate precursor capable of image recording by laser and on-press development, it can be satisfactorily developed on-press and has good print image reproducibility while receiving ink during printing. Can provide a lithographic printing method that is stable and has excellent printing durability.

[Lithographic printing plate precursor]
The lithographic printing plate precursor according to the invention has an image recording layer and a protective layer in this order on a support. The above 1. of the present invention . ~ 5. The lithographic printing plate precursor described in (1) is characterized in that the protective layer contains an inorganic layered compound, and the layered compound contains an organic cation (this is referred to as the first embodiment of the present invention). The above 6. ~ 9. The lithographic printing plate precursor described in 1) is characterized in that the image recording layer or the protective layer contains a specific phosphonium compound (this is referred to as the second aspect of the present invention).
Hereinafter, elements and components constituting the lithographic printing plate precursor according to the invention will be described.

(Protective layer)
In the lithographic printing plate precursor according to the present invention, a protective layer is provided on the image recording layer in order to prevent scratches and the like in the image recording layer, to block oxygen, and to prevent ablation during high-intensity laser exposure.
First, the protective layer in the 1st aspect of this invention is demonstrated.
The inorganic layered compound used in the present invention is a particle having a thin flat plate shape and contains an organic cation as a counter ion. Such an inorganic layered compound containing an organic cation may be synthesized and used in advance, or may be subjected to salt exchange between an organic cationic compound and an inorganic layered compound having an inorganic cation as a counter ion in a protective coating solution.

Examples of the inorganic layered compound before counter-ionizing the organic cation include, for example, the following general formula (II) A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂
[However, A is any of Li ⁺ , K ⁺ , Na ⁺ , Ca ⁺² , Mg ⁺² , and B and C are any of Fe (II), Fe (III), Mn, Al, Mg, 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. Synthetic mica includes non-swellable mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 ( Si ₄ O ₁₀ ) F ₂ , Na or Li teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , montmorillonite-based Na or Li hectorite (Na, Li) _1/8 Mg _2/5 Li Examples thereof include swelling mica such as _1/8 (Si ₄ O ₁₀ ) F ₂ . Synthetic 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 charge, and in order to compensate for this, cations such as Li ⁺ , Na ⁺ , Ca ²⁺ and Mg ²⁺ are adsorbed between the layers. These inorganic layered compounds swell with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have this tendency and are useful in the present invention, and swellable synthetic mica is particularly preferably used.

  The inorganic layered compound containing an organic cation of the present invention is a compound in which the cation adsorbed between A or the layer of the above general formula is an organic cation.

The organic cation used in the present invention is a cation of an organic cationic compound (for example, amine salt, quaternary ammonium salt, phosphonium salt, sulfonium salt, etc.).
Specifically, as the amine salt, a primary amine salt (for example, the following formula (1)), a secondary amine salt (for example, the following formula (2)), a tertiary amine salt (for example, the following formula (3)), a modification Examples thereof include amine salts (for example, the following formulas (4) to (6)) and imidazoline type amine salts (for example, the following formula (7)).
Moreover, specifically as a quaternary ammonium salt, the compound shown by following formula (8)-(15), the pyridinium salt shown by following formula (16)-(19), the alkyl shown by following formula (20) Examples thereof include quinolinium salts, imidazolinium salts represented by the following formula (21), and benzimidazolium salts represented by the following formula (22).
Examples of the phosphonium salt include a compound represented by the following formula (23), and examples of the sulfonium salt include a compound represented by the following formula (24).

In the above formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₇ , R ₁₈ , R ₁₉ , R ₂₀ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ , R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ , R ₃₆ , R ₃₇ , R ₃₈ , _{R 39, R 40, R 41} , R 42, R 44, R 45, R 46, R 48, R 49, R 50, R 52, R 53, R 54, R 55, R 57, R 59, R 61 , R ₆₂ , R ₆₃ , R ₆₄ , R ₆₅ , R ₆₆ , R ₆₇ , R ₆₈ , R ₆₉ , R ₇₀ , R ₇₁ , R ₇₂ may each independently have a substituent, Represents a saturated or unsaturated hydrocarbon monovalent group having 1 to 24 carbon atoms which may have an ethyleneoxy group or a propyleneoxy group. These hydrocarbon monovalent groups may be either chain or cyclic. Examples of saturated or unsaturated hydrocarbon monovalent groups include alkyl groups, cycloalkyl groups, alkenyl groups, cycloalkenyl groups, aryl groups, aralkyl groups, phenyl groups, and benzyl groups. Substituents include halogen and hydroxyl groups.

In the above formula, R ₈ , R ₁₂ , R ₁₆ , R ₂₅ , R ₃₀ , R ₃₅ , R ₄₃ , R ₄₇ , R ₅₁ , R ₅₆ , R ₅₈ , R ₆₀ are each independently a single bond or substituted A saturated or unsaturated hydrocarbon divalent group having 1 to 24 carbon atoms which may have a group and may have an ethyleneoxy group or a propyleneoxy group in the molecule. These hydrocarbon divalent groups may be either chain or cyclic. Examples of these hydrocarbon divalent groups include alkylene groups, cycloalkylene groups, alkenylene groups, cycloalkenylene groups, arylene groups, aralkylene groups, and the like. Substituents include halogen and hydroxyl groups. X ⁻ represents an anion.

  In addition, you may use together an inorganic cation in the range which does not impair the effect of this invention.

  In addition, the organic layered compound may be pre-ionized with an organic cation, or the compound containing the organic cation and the inorganic layered compound may be subjected to salt exchange in the protective layer coating solution.

  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.

The average particle diameter of the inorganic layered compound used in the present invention is 1 to 20 μm, preferably 1 to 10 μm, particularly preferably 2 to 5 μm. When the particle diameter is smaller than 1 μm, the permeation of oxygen and moisture is insufficient, and the effects of the present invention cannot be fully exhibited. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

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

  It is preferable that content of the inorganic stratiform compound in a protective layer is 5/1-1/100 by mass ratio with respect to the quantity of the binder used for a protective layer. Even when a plurality of types 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. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxyl groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester modification of vinyl alcohol and various organic acids. Polyvinyl alcohol having various degrees of polymerization having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, etc. at the polymer chain end is also preferably used.

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

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 spread on 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. It is the range of 02-1g.

Next, the protective layer in the 2nd aspect of this invention is demonstrated.
The phosphonium compound that can be included in the protective layer of the second aspect is represented by the following general formula (I). This phosphonium compound has a function of stabilizing the ink receiving property of the image area without deteriorating the on-press developability.

In the formula, each of R _{1 to} R ₄ independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylthio group, an arylthio group, a heterocyclic group, or a hydrogen atom. Represent. At least two of R _{1 to} R ₄ may be bonded to form a ring. X ⁻ represents an anion.
Here, when R _{1 to} R ₄ are an alkyl group, an alkoxy group, or an alkylthio group, the carbon number is usually 1 to 20, and when the R _{1 to} R ₄ are an alkenyl group or an alkynyl group, the carbon number is usually 2 to 15 and a cycloalkyl group. In some cases, the number of carbon atoms is usually 3 to 8, the aryl group is a phenyl group, a naphthyl group, etc., the aryloxy group is a phenoxy group, a naphthyloxy group, etc., the arylthio group is a phenylthio group, etc. Examples of the group include a furyl group and a thienyl group. Examples of the substituent that may be present include, for example, alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, alkoxy groups, alkoxycarbonyl groups, acyl groups, alkylthio groups, aryl groups, aryloxy groups, arylthio groups. Group, sulfino group, sulfo group, phosphino group, phosphoryl group, amino group, nitro group, cyano group, hydroxy group, halogen atom and the like. These substituents may further have a substituent.

Examples of the anion represented by X ⁻ include inorganic acid anions such as Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ and SO ₄ ⁻² , organic carboxylate anions, and organic sulfonate anions. Examples of the organic group of the organic carboxylate anion and organic sulfonate anion include methyl, ethyl, propyl, butyl, phenyl, methoxyphenyl, naphthyl, fluorophenyl, difluorophenyl, pentafluorophenyl, thienyl, pyrrolyl and the like.
X ^- is preferably an anion represented ^{by, Cl -, Br -, I} - an inorganic acid ion or an alkyl group such as an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylthio group And an organic carboxylate anion or an organic sulfonate anion having a substituent selected from a heterocyclic group and the like. These substituents may further have a substituent.
Specific examples of phosphonium compounds suitable for the present invention are shown below.

The amount of the phosphonium compound added to the protective layer is 0.01 to 2 in the solid content of the protective layer.
0 mass% is preferable, 0.05-10 mass% is still more preferable, and 0.1-5 mass% is the most preferable. The addition to the fountain solution is preferably 0.001 to 5% by mass, more preferably 0.005 to 1% by mass, and most preferably 0.01 to 0.1% by mass.

Next, the protective layer in the second embodiment other than the phosphonium compound will be described.
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.

  Examples of the material used for the protective layer include water-soluble polymer compounds that are relatively excellent in crystallinity. Specific examples include water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, and polyacrylic acid. Among these, when polyvinyl alcohol (PVA) is used as a main component, the best results are obtained for basic characteristics such as oxygen barrier properties and development removability. The polyvinyl alcohol may be partially substituted with an ester, ether or acetal as long as it contains an unsubstituted vinyl alcohol unit for providing the oxygen barrier property and water solubility necessary for the protective layer, and a part of the other You may have a copolymerization component.

  As specific examples of polyvinyl alcohol, those having a hydrolysis degree of 71 to 100 mol% and a polymerization degree of 300 to 2400 are preferably mentioned. Specifically, for example, 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, and L-8 are mentioned.

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

The protective layer of the second aspect of the present invention preferably contains an inorganic layered compound described in, for example, JP-A No. 11-38633. Good oxygen barrier properties can be obtained by combining the inorganic layered compound and the binder.
Examples of the inorganic stratiform compound used herein include the inorganic stratiform compound before the counterionization of the organic cation, such as the compound represented by the general formula (II).

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. Therefore, the aspect ratio is 20 or more, preferably 100
Above, 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. Prevent deterioration.

  The amount contained in the protective layer of the inorganic stratiform compound is 5% by mass to 55% by mass with respect to the total solid content of the protective layer. Preferably they are 10 mass%-40 mass%. When the content is less than 5% by mass, there is no effect on the adhesion resistance. Even when a plurality of types of inorganic layered compounds are used in combination, the total amount of these inorganic layered compounds is preferably the above-described mass%.

As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers based on water-soluble polymer compounds Mass% can be added.
The thickness of the protective layer is suitably from 0.05 to 4 μm, particularly preferably from 0.1 to 2.5 μm.

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

On the other hand, various proposals have been made to improve the adhesion between the image recording layer and the protective layer. For example, in JP-A-49-70702, a hydrophilic polymer mainly composed of polyvinyl alcohol is mixed with 20 to 60% by mass of an acrylic emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer, etc. It is described that sufficient adhesion can be obtained by laminating on a recording layer. Any of these known techniques can be used in the present invention. The method for applying the protective layer is described in detail, for example, in US Pat. No. 3,458,311 and JP-B-55-49729.
Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (for example, a water-soluble dye) that is excellent in the transparency of infrared rays used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved.

(Image recording layer)
Next, the image recording layer in the planographic printing plate precursor according to the invention will be described in detail.
The image recording layer of the present invention contains (A) an actinic ray absorber, (B) a polymerization initiator, and (C) a polymerizable compound, and can be removed by printing ink, fountain solution or both. is there.
Hereinafter, each component constituting the image recording layer will be described in detail.

<(A) Actinic ray absorber>
The actinic ray absorber used in the present invention absorbs light emitted from an exposure light source, efficiently generates radicals from a polymerization initiator in photon mode and / or heat mode, and contributes to improving the sensitivity of a lithographic printing plate precursor It is a compound. The actinic ray absorber is preferably an infrared absorber when the lithographic printing plate precursor is imagewise exposed with an infrared laser, and a wavelength of 250 to 420 nm when the lithographic printing plate precursor is exposed imagewise with an ultraviolet laser. Sensitizing dyes that absorb the light are preferred.

(A1) Infrared Absorber The infrared absorber used in the present invention is preferably a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

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

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

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

In formula (i), X ¹ represents a hydrogen atom, a halogen atom, -NPh _2, X ² -L ¹ or a group shown below.

X ² in the general formula (i) represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ is a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or carbon containing a hetero atom. A hydrocarbon group having 1 to 12 atoms is shown. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. Xa ^- the Za described later ^- is defined as for, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom. Ph represents a phenyl group.

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

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

Specific examples of the cyanine dye represented by the general formula (i) that can be suitably used in the present invention include paragraphs [0017] to [0019] of JP-A No. 2001-133969.
] Can be mentioned.
Other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057.
Furthermore, the infrared absorber is preferably water-soluble, but when it is water-insoluble, it can be added by a method such as dispersion or dissolution in a mixed solvent.

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

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

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

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

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

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

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

  Among these infrared absorbers described above, a preferable dye is a cyanine dye represented by the general formula (i).

(A2) Sensitizing dye The sensitizing dye used in the present invention is a compound having absorption at a wavelength of 250 to 420 nm. Specific examples thereof include benzoin, benzoin methyl ether, benzoin ethyl ether, 9-fluorenone, 2- Chloro-9-fluorenone, 2-methyl-9-fluorenone, 9-anthrone, 2-bromo-9-anthrone, 2-ethyl-9-anthrone, 9,10-anthraquinone, 2-ethyl-9,10-anthraquinone, 2-t-butyl-9,10-anthraquinone, 2,6-dichloro-9,10-anthraquinone, xanthone, 2-methylxanthone, 2-methoxyxanthone, thioxanthone, benzyl, dibenzalacetone, p- (dimethylamino) ) Phenylstyryl ketone, p- (dimethylamino) phenyl p- Examples thereof include methyl styryl ketone, benzophenone, p- (dimethylamino) benzophenone (or Michler's ketone), p- (diethylamino) benzophenone, and benzanthrone.

  Furthermore, preferred sensitizing dyes in the present invention include compounds represented by the general formula (ii) described in Japanese Patent Publication No. 51-48516.

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

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

Specific examples of the compound represented by the general formula (ii) are those having a chemical structure combining these Z ² , R ¹⁴ and R ¹⁵ , and many exist as known substances. Therefore, it can be used by appropriately selecting from these known ones. Furthermore, preferred sensitizing dyes in the present invention include merocyanine dyes described in JP-B-5-47095 and ketocoumarin compounds represented by the following general formula (iii).

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

  Further, as the sensitizing dye, a merocyanine dye described in JP-A No. 2000-147763 can also be used. Further, sensitizing dyes disclosed in JP-A No. 2001-100412 are also suitable. Specifically, the following compounds can be mentioned.

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

<(B) Polymerization initiator>
The polymerization initiator that can be used in the present invention is a compound (radical polymerization initiator) that initiates and accelerates the polymerization of a compound having a polymerizable unsaturated group by generating radicals by light, heat, or both. is there. Examples of the polymerization initiator that can be used in the present invention include known thermal polymerization initiators, compounds having a bond with a small bond dissociation energy, and photopolymerization initiators.

  Examples of the polymerization initiator as described above include organic halogen compounds, carbonyl compounds, organic peroxides, azo polymerization initiators, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boron compounds, disulfone compounds, and oximes. Examples thereof include ester compounds, oxime ether compounds, and onium salt compounds.

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

  More preferably, an s-triazine derivative having at least one mono, di, or trihalogen-substituted methyl group bonded to the s-triazine ring, specifically, for example, 2,4,6-tris (monochloromethyl)- s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -s-triazine, 2-methyl-4,6-bis (trichloromethyl)- s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine 2- (3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [ 1- (p-methoxyphenyl) -2,4-butadienyl] -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis (trichloromethyl) -s-triazine, 2- (P-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (pi-propyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- ( p-tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxynaphthyl) -4,6-bis (trichloromethyl) -s-triazine, 2-Fe Ruthio-4,6-bis (trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2- [4- (p-hydroxybenzoylamino) phenyl] -4 , 6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (dibromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine, 2-methyl- Examples include 4,6-bis (tribromomethyl) -s-triazine, 2-methoxy-4,6-bis (tribromomethyl) -s-triazine, and the like.

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

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

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

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

  Examples of the hexaarylbiimidazole compound include the specifications of JP-B-6-29285, US Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. And, specifically, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-bromophenyl) )) 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2 ′ -Bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5,5 '-Tetraphenyl Imidazole, 2,2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5 Examples include 5′-tetraphenylbiimidazole, 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole.

Examples of the organoboron compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188585, JP-A-9-188686, JP-A-9-188710, JP-A 2000-. 131837, Japanese Patent Application Laid-Open No. 2002-107916, Japanese Patent No. 2764769, Japanese Patent Application Laid-Open No. 2002-116539, and Kunz, Martin, “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”, etc. Organoboron salts described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, and organic boron oxosulfonium complexes; No. 175554, JP-A-6-175 Organoboron iodonium complexes described in JP-A No. 553, organoboron phosphonium complexes described in JP-A-9-188710, JP-A 6-348011, JP-A 7-128785, JP-A 7-140589, Examples thereof include organoboron transition metal coordination complexes such as JP-A-7-306527 and JP-A-7-292014.

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

  Examples of the oxime ester compound include J.M. C. S. Perkin II (1979) 1653-1660), J. MoI. C. S. Perkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, compounds described in JP-A 2000-66385, compounds described in JP-A 2000-80068, specifically, And a compound represented by the structural formula:

  Examples of the oxime ether compound include compounds described in JP-A-8-202035 and JP-A-10-237118. Specifically, the compound shown by the following structural formula is mentioned.

Examples of the onium salt compound include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055, 4,069,056, phosphonium salts described in European Patent Nos. 104,143, US Pat. Nos. 339,049, 410,201, JP -150848, JP-A-2-296514, iodonium salts, European Patent Nos. 370,693, 390,214, 233,567, 297,443, and 297 442, U.S. Pat. No. 4,933,377,
161,811, 410,201, 339,049, 4,760,013, 4,734,444, 2,833,827, Germany The sulfonium salts described in the specifications of Patent Nos. 2,904,626, 3,604,580, and 3,604,581, J. Pat. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), and onium salts such as arsonium salts.

  Particularly preferred from the standpoint of reactivity and stability are the oxime ester compounds or onium salts (diazonium salts, iodonium salts or sulfonium salts). In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.

  The onium salt suitably used in the present invention is an onium salt represented by the following general formulas (RI-I) to (RI-III).

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

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

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

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

  The polymerization initiator used in the present invention preferably has a maximum absorption wavelength of 400 nm or less. More preferably, the maximum absorption wavelength is 360 nm or less, and most preferably 300 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the white light safety of the lithographic printing plate precursor is improved.

  These polymerization initiators are added in a proportion of 0.1 to 50% by mass, preferably 0.5 to 30% by mass, particularly preferably 1 to 20% by mass, based on the total solid content constituting the image recording layer. Can do. Within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained. These polymerization initiators may be used alone or in combination of two or more. Moreover, these polymerization initiators may be added to the same layer as other components, or another layer may be provided and added thereto.

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

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

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

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

  Examples of other esters include aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, JP-A-59- Those having an aromatic skeleton described in JP-A No. 5241 and JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used. 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 No. 54-21726.

  Further, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable. Specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinylurethane compound 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 Etc.

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

  Also, 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- Urethane compounds having an ethylene oxide skeleton described in Japanese Patent No. 17654, Japanese Patent Publication No. 62-39417, and Japanese Patent Publication No. 62-39418 are also suitable. Furthermore, addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 are used. Depending on the case, it is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-A-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, 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.

About these polymerizable compounds, the details of usage such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image area, that is, the cured film, those having three or more functionalities are preferable. Further, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
In addition, the compatibility and dispersibility with other components in the image recording layer (for example, binder polymer, polymerization initiator, colorant, etc.), the selection and use method of the polymerizable compound is an important factor, 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 adhesion to a support or a protective layer described later.

  The polymerizable compound is used in the image recording layer in an amount of preferably 5 to 80% by mass, more preferably 25 to 75% by mass. These may be used alone or in combination of two or more. In addition, the usage of the polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. The layer construction and coating method such as undercoating and overcoating can also be carried out.

<(D) Binder polymer>
In the present invention, a binder polymer can be used for improving the film characteristics and on-press developability of the image recording layer. A conventionally well-known thing can be used as a binder polymer without a restriction | limiting, The linear organic 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.

More preferred are (meth) acrylic resins, that is, polymers of (meth) acrylic acid esters. Among these, a copolymer of an alkyl (meth) acrylate and a monomer having a —CH ₂ CH ₂ O— structure in the R portion of —COOR in the (meth) acrylic acid ester is preferable. Although a specific example is shown below, it is not limited to these.

  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 or may be introduced by a polymer reaction.

  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 ethylenically unsaturated bonds in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, at least of the ester or amide residues (R of -COOR or CONHR) Mention may be made of polymers having some ethylenically unsaturated bonds.

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 a carbon number of 1 to 20 represents an alkyl group, an aryl group, 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, and n represents an integer of 1 to 10. X represents a dicyclopentadienyl residue.).

Specific examples of the ester residue include —CH ₂ CH═CH ₂ , —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 OCOC (CH 3) = CH 2, -CH 2 CH 2 OCOCH = CH 2, -CH 2 CH 2 -NHCOO (wherein, X represents a dicyclopentadienyl residue.) -CH ₂ CH = CH ₂ and CH ₂ CH ₂ O-X and the like.
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

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

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

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

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

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

  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. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.

The binder polymer may be a random polymer, a block polymer, a graft polymer, or the like, but is preferably a random polymer.
Such a binder polymer can be synthesized by a conventionally known method. The binder polymer having a crosslinkable group in the side chain can be easily synthesized by radical polymerization or polymer reaction.

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 and more preferably 20 to 80% by mass with respect to the total solid content of the image recording layer. 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.

<(E) Phosphonium compound>
The second aspect of the present invention is characterized in that the image recording layer and / or the protective layer contains a phosphonium compound. The phosphonium compound that can be used in the image recording layer of the second aspect is a compound represented by the aforementioned general formula (I), and specific examples thereof include those described above. This phosphonium compound has a function of stabilizing the ink receiving property of the image area without deteriorating the on-press developability.

  The amount of the phosphonium compound added to the image recording layer of the second aspect is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, based on the solid content of the image recording layer. ˜5% by mass is most preferred. The addition to the fountain solution is preferably 0.001 to 5% by mass, more preferably 0.005 to 1% by mass, and most preferably 0.01 to 0.1% by mass.

<(F) Other components of image recording layer>
In the image recording layer of the present invention, components other than those described above, for example, surfactants, colorants, print-out agents, polymerization inhibitors (thermal polymerization inhibitors), higher fatty acid derivatives, plasticizers, inorganic fine particles, low molecular hydrophilicity A functional compound or the like.

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

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

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

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

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

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

Surfactant can be used individually or in combination of 2 or more types.
The surfactant is preferably contained in the total solid content of the image recording layer in an amount of 0.001 to 10% by mass, and more preferably 0.01 to 5% by mass.

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

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

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

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

  It is preferable to add the dye whose color is changed by an acid or a radical at a ratio of 0.01 to 10% by mass in the total solid content of the image recording layer.

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

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

The image recording layer in the invention may contain a plasticizer in order to improve the 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 is preferably contained in the image recording layer at a ratio of about 30% by mass or less.

The image recording layer in the present invention may contain inorganic fine particles in order to enhance the interfacial adhesion by surface roughening, improve the cured film strength of the image area, and improve the on-press developability of the non-image area.
As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate or a mixture thereof can be preferably mentioned.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 μm to 3 μm. Within the above range, it is possible to form a non-image portion 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.

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

<Formation of image recording layer>
In the present invention, when the above components are contained in the image recording layer, the above components can be contained in fine particles such as microcapsules if necessary. The components to be encapsulated can be included in the fine particles at an arbitrary ratio, and the remainder can be contained outside the fine particles. The on-press developability of the image recording layer is improved by containing fine particles.

  As a method for making the above-mentioned image recording layer constituent components fine, known methods can be applied. For example, as a method for producing fine particles, 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, and 42. Method by interfacial polymerization found in US Pat. No. 4,446, method by precipitation of polymer found in US Pat. Nos. 3,418,250 and 3,660,304, isocyanate polyol wall found in US Pat. No. 3,796,669 A method using a material, a method using an isocyanate wall material found in U.S. Pat. No. 3,914,511, a urea-formaldehyde system found in U.S. Pat. Nos. 4001140, 4087376, and 4089802, or Urea formaldehyde-resorcinol wall formation A method using a material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose as shown in US Pat. No. 4,025,445, and a monomer polymerization as shown in JP-B-36-9163 and 51-9079 In-situ method, British Patent No. 930422, US Pat. No. 3,111,407 spray drying method, British Patent No. 952807, No. 967074, such as electrolytic dispersion cooling method, It is not limited to these.

A preferable fine particle wall used in the present invention has a three-dimensional cross-linking and a property of swelling with a solvent. From this point of view, the fine wall material is preferably polyurea, polyurethane, polyether, polycarbonate, polyamide, and mixtures thereof, and polyurea and polyurethane are particularly preferred. 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 fine particle wall.

  The average particle size of the fine particles 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 in the present invention is formed by preparing and applying a coating solution by dispersing or dissolving necessary constituents in a solvent using any of the above-described embodiments. 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.

Image recording layer coating weight (solids) is preferably from ^{0.3~3.0g / m 2, 0.5~1.5g / m} 2 is more preferable.
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

(Support)
The support used for the lithographic printing plate precursor according to the 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.

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

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

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

The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the 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)
After the surface treatment is applied to the support or after the undercoat layer is formed, a back coat can be provided on the back surface of the support, if necessary.
Examples of the back coat include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organometallic compounds or inorganic metal compounds described in JP-A-6-35174. A coating layer made of a metal oxide obtained in this manner is preferred. Among them, it is inexpensive to use a silicon alkoxy compound such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4. It is preferable in terms of easy availability.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, particularly in the case of an on-press development type lithographic printing plate precursor, an undercoat layer can be provided between the image recording layer and the support, if necessary. Since the undercoat layer easily peels off the image recording layer from the support in the unexposed area, the 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 compound (undercoat compound), specifically, a silane coupling agent having an addition polymerizable ethylenic double bond reactive group described in JP-A-10-282679, Preferable examples include phosphorus compounds having an ethylenic double bond reactive group described in JP-A-2-304441.
As the most preferable undercoat compound, a polymer resin obtained by copolymerizing a monomer having an adsorptive group / a monomer having a hydrophilic group / a monomer having a crosslinkable group may be mentioned.

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 by the following method, for example.
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 on which the test compound is applied is thoroughly washed with a readily soluble / BR> N medium, and the residual amount of the test compound that has not been removed by washing is measured to calculate the adsorption 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 1 mg even after the washing treatment as described above.
/ M ² or more of the remaining compound.

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 are phenolic hydroxyl groups, carboxyl groups, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ — and —COCH _2. Contains COCH ₃ . Among them -OPO ₃ H ₂ and -PO ₃ H ₂ are 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 of the monomer having an adsorptive group 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 preferably each independently 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—, where 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 (II), Z is a functional group adsorbed on 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.

  Examples of typical monomers represented by formula (III) or (IV) are shown below.

  Examples of the hydrophilic group of the undercoat polymer resin that can be used in the present invention include a hydroxy group, a carboxyl group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, a hydroxypropyl group, a polyoxypropyl group, and an amino group. Preferred examples include a group, an aminoethyl group, an aminopropyl group, an ammonium group, an amide group, a carboxymethyl group, a sulfonic acid group, and a phosphoric acid group. Among them, a monomer having a sulfonic acid group exhibiting high hydrophilicity is preferable. Specific examples of the monomer having a sulfonic acid group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, and acrylamide t-butylsulfonic acid. , 2-acrylamido-2-methylpropanesulfonic acid, and (3-acryloyloxypropyl) butylsulfonic acid sodium salt and amine salt. Among them, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferable from the viewpoint of hydrophilic performance and synthetic handling.

  The water-soluble polymer resin for the undercoat layer of the present invention preferably has a crosslinkable group. The crosslinkable group can improve the adhesion with the image area. In order to impart crosslinkability to the polymer resin for the undercoat layer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the side chain of the polymer, or paired with the polar substituent of the polymer resin. It can be introduced by forming a salt structure with a compound having a charged 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.
As the monomer having a crosslinkable group of the polymer resin for undercoat layer, an ester or amide of acrylic acid or methacrylic acid having the crosslinkable group is suitable.

  The content of the crosslinkable group in the polymer resin for the undercoat layer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol per 1 g of the polymer resin. More preferably, it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol. Within this range, both good sensitivity and dirtiness and good storage stability can be obtained.

The polymer resin for the undercoat layer 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 is preferable. More preferably, it is 250,000. The polydispersity (mass average molecular weight / number average molecular weight) is preferably 1.1 to 10.
The polymer resin for the undercoat layer may be any of a random polymer, a block polymer, a graft polymer, etc., but is preferably a random polymer.

The undercoat polymer resin may be used alone or in combination of two or more.
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.

It is a particularly preferable embodiment that the compound having a crosslinkable group further has a support adsorbing group and a hydrophilicity-imparting group in the molecule from the viewpoints of further improvement of adhesiveness, on-press developability and stain resistance. is there. Here, the support adsorptive group is, for example, a metal, metal oxide, hydroxyl group, etc. present on a support subjected to an anodizing treatment or a hydrophilization treatment, and generally an ionic bond, a hydrogen bond, a coordinate bond or It is a group that causes bonds due to intermolecular forces. As the support adsorptive group, an acid group or an onium group is preferable. The acid group is preferably a group having an acid dissociation constant (pKa) of 7 or less, specifically, —COOH, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO _2. -, -SO ₂ NHSO _2- and the like. Particularly preferred among these is -PO ₃ H _2. The onium group is an onium group derived from an atom of Group 5B (Group 15) or Group 6B (Group 16) of the periodic table, more preferably an onium group generated from a nitrogen atom, a phosphorus atom or a sulfur atom. And particularly preferred is an onium group derived from a nitrogen atom. Examples of the hydrophilicity-imparting group include an ethylene oxide group (—OCH ₂ CH ₂ —) and a sulfonic acid group.
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.

[Plate making of lithographic printing plate precursor]
The above-described lithographic printing plate precursor of the present invention is exposed imagewise by exposure through a transparent original having a line image, a halftone dot image or the like, or by laser scanning exposure with digital data. Examples of the exposure light source include a carbon arc, a high-pressure mercury lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, a halogen lamp, an ultraviolet light laser, a visible light laser, and an infrared light laser. A laser is particularly preferable, and examples thereof include a solid-state laser and a semiconductor laser that emit infrared light of 760 to 1200 nm, and a semiconductor laser that emits light of 250 to 420 nm. When a laser is used, it is preferable to perform scanning exposure like an image according to digital data. In order to shorten the exposure time, it is preferable to use a multi-beam laser device.
When an infrared laser is used, the exposure time per pixel is preferably within 20 μs. Moreover, it is preferable that irradiation energy amount is 10-300 mJ / cm < ² >.
When an ultraviolet laser is used, the pixel residence time is preferably as short as possible in order to minimize the competitive reaction with oxygen, and is preferably 1 millisecond or less. More preferably, it is 500 μs or less, and most preferably 100 μs or less. The amount of energy is preferably 0.1 to 10 mJ / cm ² .

The lithographic printing plate precursor according to the present invention is imagewise exposed with a laser beam, and then supplied with oil-based ink and an aqueous component for printing without any development process.
Specifically, after exposing a lithographic printing plate precursor with a laser beam, mounting it on a printing machine without passing through a development processing step, after mounting the lithographic printing plate precursor on a printing machine, on the printing machine Examples include a method of performing exposure with laser light and printing without going through a development processing step.

After exposing the lithographic printing plate precursor imagewise with a laser beam and supplying it with an aqueous component and oil-based ink without passing through a development process such as a wet development process, in the exposed part 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 area, 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 in that area.
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. Here, the water-based component or 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 image recording layer in the unexposed area. It is preferable to supply. As the aqueous component and oil-based ink, a 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.

[Lithographic printing method]
In the lithographic printing method of the present invention, the fountain solution is a fountain solution containing a phosphonium compound represented by the general formula (I). Other steps from image exposure to printing can be performed in the same manner as the plate making of the lithographic printing plate precursor. According to the lithographic printing method using the fountain solution, even when the lithographic printing plate precursor not containing the phosphonium compound is used, the effects of the present invention such as stable ink acceptability during printing can be obtained.

As components other than the phosphonium compound of dampening water used in the lithographic printing method of the present invention, components described in JP-A-5-112085, JP-A-6-183171 and the like can be appropriately used.
For example, (a) hydrophilic polymer compounds having film-forming properties include hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxybutylmethylcellulose, and cellulose derivatives such as glyoxal-modified products of these cellulose derivatives. 20 to 90% of derivatives can be preferably used. Among these derivatives, hydroxypropyl cellulose is particularly preferable. These derivatives may be used alone or in combination of two or more, and the range that can be suitably used is 0.1 to 10% by mass.
Water-soluble polymer compounds other than cellulose derivatives can be used in combination. For example, gum arabic, starch derivatives (eg, dextrin, enzymatically degraded dextrin, hydroxypropylated enzymatically degraded dextrin, carboxymethylated starch, phosphate starch, octenyl succinated starch), alginate, fibrin derivatives (eg, carboxymethylcellulose, carboxy Natural products such as ethyl cellulose and methyl cellulose) and modified products thereof, polyethylene glycol and copolymers thereof, polyvinyl alcohol and derivatives thereof, polyvinyl pyrrolidone, polyacrylamide and copolymers thereof, polyacrylic acid and copolymers thereof, vinyl methyl ether / Maleic anhydride copolymer, vinyl acetate / maleic anhydride copolymer, polystyrene sulfonic acid and a composite of the copolymer. These polymer compounds can be used alone or in combination, and the concentration range of use is preferably in the range of 0.005 to 1% by mass in the fountain solution composition.

  (B) Examples of pH buffering agents include water-soluble organic acids, inorganic acids, or salts thereof. The pH buffering agent is effective in adjusting the pH of the fountain solution or buffering the pH, and appropriate etching or anticorrosion of the lithographic printing plate support. Examples of preferable organic acids include citric acid, ascorbic acid, malic acid, tartaric acid, lactic acid, acetic acid, gluconic acid, hydroxyacetic acid, succinic acid, malonic acid, maleic acid, levulinic acid, phytic acid, and organic phosphonic acid. Examples of inorganic acids include phosphoric acid, nitric acid, and sulfuric acid. Further, alkali metal salts, alkaline earth metal salts or ammonium salts of these organic acids and / or inorganic acids, and organic amine salts are also preferably used. These organic acids, inorganic acids and / or salts thereof may be used alone or in combination. The above combination may be used. Alkali metal hydroxides, phosphoric acid, alkali metal salts, alkali metal carbonates, silicates, and the like can also be used.

(C) As a compound for further improving the wetting of the water supply roller and realizing the stabilization of the water supply, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether , Tripropylene glycol monomethyl ether, tetrapropylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monoethyl ether, tetrapropylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol mono Propyl ether, tripropylene glycol monopropyl ether, tetra Lopylene glycol monopropyl ether, propylene glycol monoisopropyl ether, dipropylene glycol monoisopropyl ether, tripropylene glycol monoisopropyl ether, tetrapropylene glycol monoisopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, Tetrapropylene glycol monobutyl ether, propylene glycol monoisobutyl ether, dipropylene glycol monoisobutyl ether, tripropylene glycol monoisobutyl ether, tetrapropylene glycol monoisobutyl ether, propylene glycol monotertiary butyl ether, dipropylene glycol Monotertiary butyl ether, tripropylene glycol monotertiary butyl ether, tetrapropylene glycol monotertiary butyl ether, polypropylene glycol having a molecular weight of 200 to 1000 and monomethyl ether, monoethyl ether, monopropyl ether and isopropyl ether, monobutyl ether, etc. Can be mentioned. These compounds may be used alone or in combination of two or more. The range which can be used conveniently is 10-70 mass%. In particular, among compounds, a compound having a surface tension of 55 dynes / cm or less in an aqueous solution of 0.1 to 0.5% by mass can be particularly preferably used.
(D) Compounds useful for concentrating dampening water include 3-methoxybutanol, 3-ethoxybutanol, 3-propoxybutanol, 3-methyl-3-methoxybutanol, 3-methyl-3-ethoxybutanol, 3 -Methyl-3-propoxybutanol and the like. These compounds can be suitably used alone or in combination of two or more. The range that can be preferably used is 0.1 to 20% by mass.

  (E) Specific examples of compounds effective in preventing deterioration of the image area of the printing plate due to solvent residues generated by water evaporation include benzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid Benzoic acid, salicylic acid, isophthalylsulfonic acid, gallic acid, phenolsulfonic acid, thiosalicylic acid, 4- (butylphenyl) -2-hydroxybenzenesulfonic acid, 4- (butylphenyl) benzenesulfonic acid, diphenylethersulfonic acid, etc. Can be mentioned. These alkali metal salts (Na, K, Li salts) and ammonium salts can also be used effectively. A suitable use range is 0.01 to 7% by mass. Two or more of these compounds can be used in combination.

  In addition, the salt which exhibits the corrosion prevention effect of the metal used for the corrosion prevention of a printing plate and a printing press is used. Specific examples include sodium nitrate, potassium nitrate, ammonium nitrate, magnesium nitrate, calcium nitrate, beryllium nitrate, aluminum nitrate, zinc nitrate, zirconium nitrate, nickel nitrate, manganese nitrate, chromium nitrate and the like. These salts may be used alone or in combination of two or more.

  Further, a surfactant may be added. For example, anionic surfactants include fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinates, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalenes. Sulfonates, alkylphenoxy polyoxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salts, N-alkyl sulfosuccinic acid monoamide disodium salts, petroleum sulfone complex salts, Sulfated castor oil, sulfated beef tallow oil, fatty acid alkyl ester sulfate esters, alkyl sulfate esters, polyoxyethylene alkyl ether sulfate esters, fatty acid monoglycerides Acid ester salts, polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylphenyl ether phosphates, styrene Examples thereof include partial saponification products of maleic anhydride copolymers, partial saponification products of olefin-maleic anhydride copolymers, naphthalene sulfonate formalin condensates, and the like. Among these, dialkyl sulfosuccinates, alkyl sulfate esters and alkyl naphthalene sulfonates are particularly preferably used.

Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl 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, poly Glycerin fatty acid partial esters, polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid die Noruamido acids, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, and trialkylamine oxides. In addition, fluorine-based surfactants and silicon-based surfactants can also be used. Of these, polyoxyethylene alkylphenyl ethers, polyoxyethylene-polyoxypropylene block polymers and the like are preferably used.

  Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, polyethylene polyamine derivatives, and the like. The content of these surfactants is 10% by mass or less, preferably 0.01 to 3.0% by mass in consideration of foaming.

  Further, ethylene glycol, triethylene glycol, butylene glycol, hexylene glycol, octanediol, diethylene glycol, glycerin, trimethylolpropane, diglycerin and the like are suitably used as the wetting agent. These wetting agents may be used alone or in combination of two or more. In general, the wetting agent is preferably used in an amount of 0.1 to 25% by mass.

  Furthermore, a chelate compound may be added to the fountain solution composition of the present invention. Usually, the fountain solution composition is diluted with tap water or well water. At this time, calcium ions or the like contained in the tap water or well water to be diluted may adversely affect the printing and cause the printed matter to be easily stained. In such a case, a chelate compound can be added to eliminate the above disadvantages. Preferred chelate compounds include, for example, ethylenediaminetetraacetic acid, its potassium salt, its sodium salt; diethylenetriaminepentaacetic acid, its potassium salt, its sodium salt; triethylenetetraminehexaacetic acid, its potassium salt, its sodium salt, hydroxyethylethylenediaminetrimethyl Acetic acid, potassium salt, sodium salt; nitrilotriacetic acid, sodium salt; 1-hydroxyethane-1,1-diphosphonic acid, potassium salt, sodium salt; aminotri (methylenephosphonic acid), potassium salt, sodium Examples thereof include organic phosphonic acids such as salts and phosphonoalkanetricarboxylic acids. Organic amine salts are also effective in place of the sodium or potassium salts of the above chelating agents. These chelating agents are selected so that they are stably present in the fountain solution composition and do not impair the printability.

Further, the fountain solution composition of the present invention contains benzotriazole, 5-methylbenzotriazole, 5-methobenzotriazole, 4-chlorobenzotriazole, 4-bromobenzotriazole, 4-bromo-6-methylbenzo as a rust inhibitor. Examples include triazole and 4-bromo-6-trifluoromethylbenzotriazole. In addition, examples of compounds in which the 1H position of these compounds is substituted with alkali metal salts (K, Na, Li) or NH ₄ , benzimidazoles and derivatives thereof, mercapto compounds and / or thioether compounds include, for example, mercaptoacetic acid, 2 -Mercaptopropionic acid, 3-mercaptopropionic acid, 4-mercaptobutanoic acid, 2,4-dimercaptobutanoic acid, 2-mercaptotetradecanoic acid, 2-mercaptomyristic acid, mercaptosuccinic acid, 2,3-dimercaptosuccinic acid, Cysteine, N-acetylcystine, N- (2-mercaptopropionyl) glycine, N- (2-mercapto-2-methylpropionyl) glycine, N- (3-mercaptopropionyl) glycine, N- (2-mercapto-2- Methylpropionyl) cysty , Penicillamine, N-acetylpenicillamine, glycine / cystine / glutamine condensate, N- (2,3-dimercaptopropionyl) glycine, 2-mercaptonicotinic acid, thiosalicylic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, 3-carboxy-2-
Mercaptopyridine, 2-mercaptobenzothiazole-5-carboxylic acid, 2-mercapto-3-phenylpropanoic acid, 2-mercapto-5-carboxyethylimidazole, 5-mercapto-1- (4-carboxyphenyl) tetrazole, N- (3,5-dicarboxyphenyl) -2-mercaptotetrazole, 2- (1,2-dicarboxyethylthio) -5-mercapto-1,3,4-thiadiazole, 2- (5-mercapto-1,3 , 4-thiadiazolylthio) hexanoic acid, 2-mercaptoethanesulfonic acid, 2,3-dimercapto-1-propanesulfonic acid, 2-mercaptobenzenesulfonic acid, 4-mercaptobenzenesulfonic acid, 3-mercapto-4- (2-sulfophenyl) -1,2,4-triazole, 2-mercaptobe Zothiazole-5-sulfonic acid, 2-mercaptobenzimidazole-6-sulfonic acid, mercaptosuccinimide, 4-mercaptobenzenesulfonamide, 2-mercaptobenzomidazole-5-sulfonamide, 3-mercapto-4- (2- (Methylaminosulfonyl) ethoxy) toluene, 3-mercapto-4- (2- (methylsulfonylamino) ethoxy) toluene, 4-mercapto-N- (p-methylphenylsulfonyl) benzamide, 4-mercaptophenol, 3-mercapto Phenol, 2-mercaptophenol, 3,4-dimercaptotoluene, 2-mercaptohydroquinone, 2-thiouracil, 3-hydroxy-2-mercaptopyridine, 4-hydroxythiophenol, 4-hydroxy-2-mercaptopyrimi 4,6-dihydroxy-2-mercaptopyrimidine, 2,3-dihydroxypropyl mercaptan, 2-mercapto-4-octylphenyl methanesulfonylaminoethyl ether, 2-mercapto-4-octylphenol methaneaminosulfonylbutyl ether, thiodiglycol Acid, thiodiphenol, 6,8-dithiooctanoic acid, 5-methoxy-2-mercaptobenzimidazole, 2-mercaptobenzimidazole-5-sulfonic acid and the like, and alkali metal salts, alkaline earth metal salts of the above compounds, Examples thereof include ammonium salts and organic amine salts. As content of these compounds, the range of 0.0001 mass%-5 mass% is preferable. Moreover, it can also be used individually or in mixture of 2 or more types.

  Furthermore, various coloring agents, antifoaming agents, preservatives and the like can be added to the fountain solution composition of the present invention. For example, food colorants can be preferably used as the colorant. For example, CI No. 19140, 15985 as a yellow dye, CI No. 16185, 45430, 16255, 45380, 45100 as a red dye, CI No. 42640 as a purple dye, CI No. 42090, 73015 as a blue dye, CI No. 42095, and the like. Moreover, as an antifoamer, a silicon antifoamer is preferable. Among them, an emulsified dispersion type and a solubilized type can be used. A preferable addition amount is in the range of 0.001 to 1% by mass.

  Further, as preservatives, phenol or derivatives thereof, formalin, imidazole derivatives, sodium dehydroacetate, 4-isothiazolin-3-one derivatives, benztriazole derivatives, derivatives of amidine or guanidine, quaternary ammonium salts, pyridine, quinoline or guanidine Derivatives, diazine or triazole derivatives, oxazole or oxazine derivatives, and the like.

  The fountain solution composition of the present invention can be obtained by making these components into water, preferably demineralized water, that is, an aqueous solution dissolved in pure water. When using the concentrate, it is economically preferable to dilute it 10 to 100 times with tap water, well water or the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. Examples 5, 12 to 25, and 27 are reference examples.

[Example 1]
(Production of support)
In order to remove rolling oil on the surface of an aluminum plate (material 1050) having a thickness of 0.3 mm, a degreasing treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, and then the hair diameter was 0.3 mm. The aluminum surface was grained using three bundle-planted nylon brushes and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) having a median diameter of 25 μm and washed thoroughly with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .
Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode. The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.
Next, a 0.5% by mass hydrochloric acid aqueous solution (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. and nitric acid electrolysis under the condition of an electric quantity of 50 C / dm ² when the aluminum plate is an anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying. The plate was provided with a direct current anodic oxide coating of 2.5 g / m ² at a current density of 15 A / dm ² using 15% by weight sulfuric acid (containing 0.5% by weight of aluminum ions) as an electrolytic solution, and then washed and dried. The body. 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.

The following undercoat liquid (1) was applied to the support so that the dry coating amount was 10 mg / m ² to prepare a support.

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

(Formation of image recording layer and protective layer)
An image recording layer coating solution (1) having the following composition was bar-coated on the support and then oven dried at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ² . Subsequently, a protective layer coating solution (1) having the following composition was applied onto the image recording layer by bar coating and oven-dried at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.15 g / m ^2. A lithographic printing plate precursor (1) was obtained.

Image recording layer coating solution (1)
-Binder polymer (1) 0.162g
・ Polymerization initiator I-13 0.100g
・ Infrared absorbing dye (1) 0.020 g
Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.385 g
-0.044 g of the following fluorosurfactant (1)
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g
・ Water 2.425g
-Fine particles synthesized as follows (1) 2.640 g

Synthesis of fine particles (1) As oil phase components, trimethylolpropane and xylene diisocyanate adduct (manufactured by Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75 mass% ethyl acetate solution), 10 g, Aronix M-215 (Toho) (Synthetic Co., Ltd.) 6.00 g and Piionin A-41C (Takemoto Yushi Co., Ltd.) 0.12 g were dissolved in ethyl acetate 16.67 g. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 2 hours. The solid content concentration of the fine particle liquid thus obtained was diluted with distilled water so as to be 15% by mass. The average particle size was 0.2 μm.

Protective layer coating solution (1)
-1.5g of the following inorganic particle dispersion (1)
・ Tetramethylammonium tetrafluoroborate salt 0.04g
・ Polyvinyl alcohol 0.06g
(Pura 105 manufactured by Kuraray Co., Ltd., saponification degree 98.5 mol%, polymerization degree 500)
・ Polyvinylpyrrolidone K30 0.01g
(Made by Tokyo Chemical Industry Co., Ltd., molecular weight Mw = 40,000)
・ Vinyl pyrrolidone and vinyl acetate copolymer LUVITEC VA64W
(ICP, copolymerization ratio = 6/4) 0.01 g
・ Surfactant Emarex 710 0.01g
Made by Nippon Emulsion Co., Ltd. ・ Ion-exchanged water 6.0g

Preparation of Inorganic Particle Dispersion (1) 6.4 g of synthetic mica Somasif ME-100 (manufactured by Corp Chemical) is added to 193.6 g of ion-exchanged water, and the average particle size (laser scattering method) is 3 μm using a homogenizer. Dispersed until The aspect ratio of the obtained dispersed inorganic particles was 1000 or more.

[Examples 2 to 4]
Lithographic printing plate precursors (2) to (4) were obtained in the same manner as in Example 1 except that the compounds shown in the table below were used instead of the tetramethylammonium tetrafluoroborate salt used in Example 1.

Example 5
An image recording layer coating solution (2) having the following composition was bar-coated on a support prepared in the same manner as in Example 1, and then oven-dried at 100 ° C. for 60 seconds to obtain a dry coating amount of 1.5 g / m ² . An image recording layer was formed. Subsequently, a protective layer coating solution (2) having the following composition was applied onto the image recording layer by bar coating, followed by oven drying at 120 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.24 g / m ^2. A lithographic printing plate precursor (5) was obtained.

Image recording layer coating solution (2)
-Binder polymer (1) 0.162g
・ Polymerization initiator I-13 0.150g
・ Polymerization initiator S-1 0.100 g
・ Infrared absorbing dye (2) 0.030 g
Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.385 g
・ Fluorosurfactant (1) 0.044g
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g
・ Water 2.425g
・ Fine particles (1) 2.640 g

Protective layer coating solution (2)
-The following inorganic particle dispersion (2) 3.0 g
・ Tetramethylammonium tetrafluoroborate salt 0.08g
・ Polyvinyl alcohol PVA105 0.08g
(Kuraray Co., Ltd., fighting degree 98.5 mol%, polymerization degree 500)
・ Polyvinylpyrrolidone K30 0.01g
(Made by Tokyo Chemical Industry Co., Ltd., molecular weight Mw = 40,000)
・ Vinyl pyrrolidone and vinyl acetate copolymer LUVITEC VA64W
(ICP, copolymerization ratio = 6/4) 0.01 g
・ Surfactant Emarex 710 0.01g
Made by Nippon Emulsion Co., Ltd. ・ Ion-exchanged water 6.0 g

Preparation of Inorganic Particle Dispersion (2) 6.4 g of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co.) is added to 193.6 g of ion-exchanged water, and the average particle size (laser scattering method) is 0. 0 using a homogenizer. Disperse until 5 μm. The aspect ratio of the obtained dispersed inorganic particles was 1000 or more.

Example 6
In the same manner as in Example 5, except that an inorganic particle dispersion having an average particle diameter of 1.5 μm was used instead of the inorganic particle dispersion having an average particle diameter of 0.5 μm used in Example 5, a planographic printing plate precursor ( 6) was obtained.

Example 7
A lithographic printing plate precursor (7) was obtained in the same manner as in Example 5 except that the inorganic particle dispersion (1) was used instead of the inorganic particle dispersion (2) used in Example 5.

Example 8
An image recording layer coating solution (3) having the following composition was bar-coated on a support prepared in the same manner as in Example 1, and then oven-dried at 140 ° C. for 60 seconds to obtain a dry coating amount of 0.8 g / m ² . An image recording layer was formed. Subsequently, a protective layer coating solution (3) having the following composition is bar-coated on the image recording layer and oven-dried at 140 ° C. for 60 seconds to form a protective layer having a dry coating amount of 0.3 g / m ^2. A lithographic printing plate precursor (8) was obtained.

Image recording layer coating solution (3)
-Binder polymer (1) 0.162g
・ Polymerization initiator S-14 0.100 g
・ Infrared absorbing dye (2) 0.030 g
Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.385 g
・ Fluorosurfactant (1) 0.044g
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g
・ Water 2.425g
・ Fine particles (1) 2.640 g

Protective layer coating solution (3)
・ 3.0 g of the above inorganic particle dispersion (1)
・ The following compound (1) 0.08 g
・ Polyvinyl alcohol PVA105 0.10g
(Kuraray Co., Ltd., fighting degree 98.5 mol%, polymerization degree 500)
・ Polyvinylpyrrolidone K30 0.02g
(Made by Tokyo Chemical Industry Co., Ltd., molecular weight Mw = 40,000)
・ Vinyl pyrrolidone and vinyl acetate copolymer LUVITEC VA64W
(ICP, copolymerization ratio = 6/4) 0.03 g
・ Surfactant Emarex 710 0.02g
Made by Nippon Emulsion Co., Ltd. ・ Ion-exchanged water 6.0 g

[Examples 9 to 11]
Lithographic printing plate precursors (9) to (11) were obtained in the same manner as in Example 8, except that the compounds shown in the table below were used instead of the compound (1) used in Example 8.

[Comparative Example 1]
A lithographic printing plate precursor was prepared in the same manner as in Example 1 except that the protective layer was not formed, and a comparative lithographic printing plate precursor (1) was obtained.

[Comparative Example 2]
A lithographic printing plate precursor was prepared in the same manner as in Example 5 except that the protective layer was not formed to obtain a comparative lithographic printing plate precursor (2).

[Comparative Example 3]
A lithographic printing plate precursor was prepared in the same manner as in Example 5 except that the tetramethylammonium tetrafluoroborate salt was not added to obtain a lithographic printing plate precursor (3) for comparison.

[Evaluation of lithographic printing plate precursor (1)]
The lithographic printing plate precursor obtained as described above was measured and evaluated for on-press developability, ink landing property and printing durability as follows.

<On-press developability>
The resulting lithographic printing plate precursor was exposed with a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser under the conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2400 dpi. The obtained exposed original plate was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without developing. Using fountain solution (Tokyo Ink Co., Ltd. CDS803 diluted 50-fold with tap water) and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) After supplying the ink, printing was started at a printing speed of 6000 sheets per hour.
When the on-press development of the unexposed part of the image recording layer was completed on the printing press and the number of printing papers required until the ink was not transferred to the printing paper was measured as on-press developability, Even when the planographic printing plate precursor was used, a printed matter having no stain on the non-image area was obtained within 100 sheets.

<Ink fillability>
After printing starts, ink gradually adheres to the image area of the lithographic printing plate, and as a result, the ink density on the paper gradually increases. The number of printed sheets when the ink density reached the standard printed matter density was measured as the ink fillability.

<Print durability>
If the printing is further continued after ink deposition, the image recording layer gradually wears. Since the wear of the image recording layer has progressed and the ink receptivity has decreased, the ink density on the printing paper begins to decrease. Printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing. The results are shown in the table below.

  As is clear from the above results, the lithographic printing plate precursor of the comparative example having no protective layer or having a protective layer using an inorganic stratiform compound not containing an organic cation is inferior in printing durability or inking property. On the other hand, the lithographic printing plate precursors of Examples 1 to 11 having a protective layer containing an inorganic stratified compound containing an organic cation according to the present invention have good on-press developability, and good printing durability and inking. Have sex.

[Examples 12 to 18]
(Production of support)
A support having an undercoat layer was prepared in the same manner as in Example 1 except that the dry coating amount of the undercoat layer was changed to 6 mg / m ² in the preparation of the support described in Example 1.

(Formation of image recording layer)
An image recording layer coating solution (4) having the following composition was bar-coated on the support and then oven dried at 100 ° C. for 60 seconds to form an image recording layer having a dry coating amount of 1.0 g / m ² . The image recording layer coating solution (4) was obtained by mixing and stirring the following photosensitive solution (1) and fine particle solution (2) immediately before coating.

Photosensitive solution (1)
-Binder polymer (1) 0.162g
・ The following polymerization initiator (1) 0.160 g
・ The following polymerization initiator (2) 0.180 g
・ The following infrared absorber (3) 0.020 g
Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.385 g
・ Fluorosurfactant (1) 0.044g
・ Methyl ethyl ketone 1.091g
-1-methoxy-2-propanol 8.210 g
-Phosphonium compounds described in Table 4 (A) Amounts described in Table 4

Fine particle liquid (2)
-Fine particles (2) synthesized as follows: 2.640 g
・ Water 2.425g

Synthesis of fine particles (2) As an oil phase component, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N, 75 mass% ethyl acetate solution) 10 g, Aronix SR-399 (Toho) (Synthesis Co., Ltd.) 6.00 g and Piionin A-41C (Takemoto Yushi Co., Ltd.) 0.12 g were dissolved in ethyl acetate 16.67 g. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 2 hours. The solid content concentration of the fine particle liquid thus obtained was diluted with distilled water so as to be 15% by mass. The average particle size was 0.2 μm.

(Formation of protective layer)
The following protective layer coating solution (4) was bar coated on the image recording layer, followed by oven drying at 125 ° C. for 75 seconds to form a protective layer having a dry coating amount of 0.15 g / m ² to form a lithographic printing plate precursor Got.

Protective layer coating solution (4)
・ Polyvinyl alcohol (PVA105 manufactured by Kuraray Co., Ltd.)
Degree of saponification 98.5 mol%, degree of polymerization 500) 6% by weight aqueous solution 2.24 g
・ Polyvinylpyrrolidone (K30) 0.0053g
-1% by weight aqueous solution of surfactant (Emalex 710 manufactured by Kao Corporation)
2.15g
Scale-like synthetic mica (MECO3L manufactured by UNICOO, average particle diameter of 1 to 5 μm)
3.4% by weight aqueous dispersion 3.75g
・ Distilled water 10.60g

[Examples 18 to 25]
An image recording layer coating solution (5) having the following composition was bar-coated on a support having the same undercoat layer used in Example 12, and then oven-dried at 100 ° C. for 60 seconds to obtain a dry coating amount of 1 An image recording layer of .3 g / m ² was formed. Further, a protective layer was provided in the same manner as in Example 12 to obtain a lithographic printing plate precursor.
The image recording layer coating solution (5) was obtained by mixing and stirring the following photosensitive solution (2) and the fine particle solution (2) immediately before coating.

Photosensitive solution (2)
-Binder polymer (1) 0.162g
・ The following polymerization initiator (3) 0.180 g
・ Infrared absorber (2) 0.038g
Polymerizable compound, Aronix M-215 (manufactured by Toa Gosei Co., Ltd.) 0.385 g
・ Fluorosurfactant (1) 0.044g
・ Methyl ethyl ketone 1.091g
-1-methoxy-2-propanol 8.210 g
-Phosphonium compounds listed in Table 4 (A) Amounts listed in Table 1

[Comparative Example 4]
A comparative lithographic printing plate precursor was obtained in the same manner as in Example 12 except that the phosphonium compound of the photosensitive solution (1) was not added.

[Comparative Example 5]
A comparative lithographic printing plate precursor was obtained in the same manner as in Example 18 except that the phosphonium compound of the photosensitive solution (2) was not added.

[Evaluation of lithographic printing plate precursor (2)]
The on-press developability, printing sensitivity and printing durability of the lithographic printing plate precursor obtained as described above were measured and evaluated as follows. The results of printing durability are shown in Table 4.

<On-press developability>
The obtained lithographic printing plate precursor was exposed with a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser under the conditions of an output of 9.6 W, an outer drum rotating speed of 150 rpm, and a resolution of 2400 dpi. The exposed original plate was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg. Use fountain solution [Ecolity 2 (Effect manufactured by Fuji Photo Film Co., Ltd.) / Water = 2/98 (volume ratio)] and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) After supplying dampening water and ink, 100 sheets were printed at a printing speed of 6000 sheets per hour. The number of print sheets required until the on-press development on the printing press of the unexposed portion of the image recording layer was completed and no ink was transferred to the print paper was measured as on-press developability.

<Print sensitivity>
With the above Trendsetter 3244VX, the output was changed to 3.2 W, 4.5 W, 6.4 W, and 9.6 W, and a 10 μm thin line was exposed under the conditions of the outer surface drum rotation speed 150 rpm and resolution 2400 dpi. The exposed original plate was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg. Using dampening water [IF102 (Fuji Photo Film Co., Ltd. etchant) / water = 3/97 (volume ratio)] and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) After supplying dampening water and ink, 100 sheets were printed at a printing speed of 6000 sheets per hour. The exposure amount that could be reproduced without interruption of a 10 μm fine line on the printed matter was measured as sensitivity.

<Print durability>
After the on-press developability was evaluated, printing was further continued. As the number of printed sheets increased, the ink density on the printing paper decreased. The printing durability was evaluated by the number of printed sheets when the ink density (reflection density) was reduced by 0.1 from the start of printing.

Example 26
The following protective layer coating solution (5) was bar-coated on the same image recording layer as in Comparative Example 5, and then oven-dried at 125 ° C. for 75 seconds to form a protective layer having a dry coating amount of 0.15 g / m ^2. This was formed to obtain a lithographic printing plate precursor.

Protective layer coating solution (5)
・ Polyvinyl alcohol (PVA105 manufactured by Kuraray Co., Ltd.)
Degree of saponification 98.5 mol%, degree of polymerization 500) 6% by weight aqueous solution 2.24 g
・ Polyvinylpyrrolidone (K30) 0.0053g
-1% by weight aqueous solution of surfactant (Emalex 710 manufactured by Kao Corporation)
2.15g
Scale-like synthetic mica (MECO3L manufactured by UNICOO, average particle diameter of 1 to 5 μm)
3.4% by weight aqueous dispersion 3.75g
・ Phosphonium compound (A-1) 0.20g
・ Distilled water 10.60g
Evaluation similar to Example 12 was implemented about the obtained printing plate precursor. The results are shown in Table 5.

  As apparent from Tables 4 and 5, according to the planographic printing plate precursor of the present invention, the on-press developability is maintained as compared with the case of using the conventional planographic printing plate precursor (Comparative Examples 4 to 5). It can be seen that the printing durability (ink acceptability) is extremely excellent.

[Example 27 and Comparative Example 6]
In the evaluation of Comparative Example 5, the same procedure as in Comparative Example 5 was performed except that the dampening water was changed to a solution obtained by diluting the α solution shown in Table 6 below with 3% (volume ratio). The same procedure as in Comparative Example 5 was repeated except that the dampening water was changed to a solution obtained by diluting the β solution shown in Table 6 below to 3% (volume ratio). did. The results are shown in Table 7.

  As is apparent from Table 7, according to the lithographic printing method of the present invention using a fountain solution containing a phosphonium compound, on-press developability as compared with a method using a normal fountain solution (Comparative Example 6). It can be seen that the printing durability (ink acceptability) is extremely excellent while maintaining the above.

Claims (2)

An image recording layer containing (A) an actinic ray absorber, (B) a polymerization initiator, and (C) a polymerizable compound, which can be removed by dampening water and / or ink, and a particle size of 1 μm. A lithographic printing plate precursor having the above-described protective layer containing an inorganic layered compound in this order, wherein the inorganic layered compound contains an organic cation. An image recording layer containing (A) an actinic ray absorber, (B) a polymerization initiator, and (C) a polymerizable compound, which can be removed by dampening water and / or ink, is formed on the support. A method for producing a lithographic printing plate precursor comprising applying an aqueous solution containing an inorganic stratiform compound having a particle size of 1 μm or more and an organic cationic compound on a recording layer to form a protective layer.