JP2007283656A - Original lithographic printing plate, its manufacturing method and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original lithographic printing plate with such advantages that aboard-the-machine developing properties are successful/stable and sensitivity/resistance to plate wear are also successful/stable, and to provide a method for manufacturing the original lithographic printing plate and a printing method. <P>SOLUTION: This original lithographic printing plate comprises an image recording layer containing a polymerizable compound, a radical polymerization initiator and a heat-fusible particle, formed on a support. After applying the image recording layer, the heat-fusible particle is made to fuse before exposure to light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate precursor, a method for producing a lithographic printing plate precursor, and a printing method. More specifically, the lithographic printing plate precursor capable of recording an image based on a digital signal and obtaining a stable printed matter, The present invention relates to a method for producing a lithographic printing plate precursor and a printing method.

  In the conventional printing process, a negative or positive film is produced from an original image, and the image is exposed to a lithographic printing plate material (lithographic printing plate precursor) having a photosensitive layer on an aluminum grain support through the film, and an alkaline development is performed. A lithographic printing plate is produced by developing with a liquid, and this is carried out by a procedure of attaching it to a printing machine and printing.

  In recent years, with the spread of computers, computer-to-plate (CTP) technology that draws original image data directly on a printing plate without using a film is becoming widespread, reducing the time and cost required for film production. Is becoming possible. Also, as a need for printed materials, there is a tendency for a small number of various types of products to print various kinds of high-quality images with the number of printed sheets of about several thousand to 10,000 sheets. For this reason, plate making using heat mode laser recording, which has a short drawing time and high resolution, is becoming the mainstream of CTP.

  Synchronizing with the spread of CTP, the printing environment has become an office, and an lithographic printing plate material that does not require an alkaline developer and does not require any development treatment from the viewpoint of environmental suitability has been desired. It was.

  A method is disclosed in which a lithographic printing plate precursor containing thermoplastic particles dispersed in a hydrophilic binder is attached to a printing machine and developed on the printing machine to produce a lithographic printing plate (for example, Patent Document 1). 2, 3). According to these techniques, it is possible to produce a printing plate without performing alkali development and without requiring a developing machine, and it is possible to provide a lithographic printing plate that does not require development processing in a pseudo manner.

  In addition, it is also described that a lithographic printing plate precursor can use a plastic film as a support in recent years without using a hydrophilic aluminum substrate as a support. Plastic film has lower thermal conductivity than metal, and can be efficiently used for image formation without diffusing heat generated in the heat-sensitive layer by laser exposure during image formation to the support. It also has the advantage of being cheaper than the body. JP-A-9-314794 discloses examples of using a support having a corona-treated surface as a printing plate using these plastic films as a support, and JP-A-11-245530 discloses a plasma treatment. A support is disclosed.

However, the conventional on-press developable lithographic printing plate precursor having a polymerizable compound, radical polymerization initiator, and heat-meltable particles in the image recording layer does not have sufficient on-press developability. In addition, higher sensitivity and higher printing durability were desired, and improvements were desired.
JP-A-9-123387 JP-A-9-123388 JP-A-9-131850

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a stable lithographic printing plate precursor and lithographic printing having good on-machine developability and stability, and good sensitivity and printing durability. An object of the present invention is to provide a method for producing a plate precursor and a printing method.

  The above object of the present invention can be achieved by the following constitution.

  1. It has an image recording layer having a polymerizable compound, a radical polymerization initiator, and heat-meltable particles on a support, and the heat-meltable particles are melted before the exposure after coating the image-recording layer. A lithographic printing plate precursor.

  2. 2. The lithographic printing plate precursor as described in 1, wherein the mass fraction of the heat-fusible particles in the image recording layer is A (mass%), and 0.25 mass% ≦ A <30 mass%.

  3. The lithographic printing plate precursor as described in 1 or 2, wherein the heat-meltable particles are wax.

  4.1. A printing method comprising printing a lithographic printing plate precursor described in 1, 2 or 3 by laser exposure based on image information and performing on-press development processing.

  5. It has an image recording layer having a polymerizable compound, a radical polymerization initiator, and heat-meltable particles on a support, and the heat-meltable particles are melted before the exposure after coating the image-recording layer. A method for producing a lithographic printing plate precursor.

  6). The lithographic printing plate precursor as described in 5 above, wherein A (mass%) is an addition mass fraction of the heat-meltable particles in the image recording layer, and 0.25 mass% ≦ A <30 mass%. Production method.

  7). The method for producing a lithographic printing plate precursor as described in 5 or 6, wherein the heat-meltable particles are wax.

  8. A printing method comprising printing a lithographic printing plate precursor produced by the method for producing a lithographic printing plate precursor as described in 8.5, 6 or 7, by performing laser exposure on the basis of image information and performing on-machine development.

  According to the present invention, it is possible to provide a lithographic printing plate precursor having a good and stable on-press developability and also having a good sensitivity and printing durability, a method for producing a lithographic printing plate precursor, and a printing method. it can.

  Hereinafter, although the best mode for carrying out the present invention will be described, the present invention is not limited to these.

  Hereinafter, the present invention will be described in detail.

  The lithographic printing plate precursor according to the invention has an image recording layer having a polymerizable compound, a radical polymerization initiator, and heat-meltable particles on a support, and after the application of the image recording layer and before exposure, the heat-melting It is characterized by melting the conductive particles.

  The lithographic printing plate precursor according to the invention may satisfy 0.25% by mass ≦ A <30% by mass, where A (% by mass) is the mass fraction added to the heat-fusible particles in the image recording layer. preferable. Furthermore, it is more preferable that 0.5% by mass ≦ A <20% by mass. When A is less than 0.25% by mass, the film strength of the image area is weakened and the printing durability may be deteriorated. On the other hand, if A exceeds 30% by mass, the film strength of the image area is increased, but ink deposition may occur in the non-image area.

  The present invention has been found for the first time to be achieved by satisfying the constitution described in the claims within the above range.

  That is, the present invention has an image recording layer having a polymerizable compound, a radical polymerization initiator and heat-meltable particles on a support, and the heat-meltable particles are melted after the application of the image recording layer and before exposure. This is very important.

  In the present invention, it has been found that by melting the heat-fusible particles after application of the image recording layer, the heat-fusible particles melt and enter the layer, thereby increasing the film strength of the image recording layer itself. Further, it has been found that the ink deposition property during printing is improved, and the on-press development property, printing durability, and sensitivity are improved.

<Heat-melting particles in the image forming layer>
The image forming layer of the lithographic printing plate precursor according to the invention contains the heat-meltable particles according to the invention. The heat-meltable particle heat according to the present invention may be selected from a heat-meltable particle that can be fused by heat and a substance that exhibits lipophilicity by heat.

Examples of heat-meltable particles that can be fused by heat include waxes, acrylic resins, ionomer resins, vinyl acetate resins, vinyl chloride resins, synthetic rubbers, polyurethane resins, polyester resins, fluorine resins, silicone resins, etc. And those obtained from latex or emulsion dispersed in water. Of these, those having a melting point of 70 to 180 ° C. are preferable, and the hydrophilic component of the surface energy is preferably 10 dyn / cm ² or less. As the hot-melt material, waxes, acrylic resins, and synthetic rubbers are particularly preferable.

  Examples of waxes that can be used in the present invention include carnauba wax, beeswax, spermaceti, wax, jojoba oil, lanolin, ozokerite, paraffin wax, montan wax, candelilla wax, ceresin wax, microcrystalline wax, rice wax, and the like. Natural wax, polyethylene wax, Fischer-Tropsch wax, montan wax derivative, paraffin wax derivative, microcrystalline wax derivative, higher fatty acid and the like. In order to facilitate emulsification, these waxes can be oxidized to introduce polar groups such as hydroxyl groups, ester groups, carboxyl groups, aldehyde groups, and peroxide groups.

  The heat-fusible particles may exhibit lipophilicity by heat. As such a substance, a hot-melt material having a melting point of 70 to 180 ° C. can be used. Natural waxes such as candelilla wax, ceresin wax, microcrystalline wax, rice wax, polyethylene wax, Fischer-Tropsch wax, montan wax derivative, paraffin wax derivative, microcrystalline wax derivative, higher fatty acid, etc. Copolymers of one or more of methyl acid, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, styrene, etc., and synthetic rubbers are polybutadiene, polyiso Rene, polychloroprene, styrene-butadiene copolymer, acrylic ester-butadiene copolymer, methacrylic ester-butadiene copolymer, isobutylene-isoprene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer And a styrene-isoprene copolymer. In addition, ionomer resins, vinyl acetate resins, vinyl chloride resins, polyurethane resins, polyester resins, fluorine resins, silicone resins, and the like can be used. These lipophilic agents are preferably used in the form of an aqueous dispersion in terms of ease of coating. As another embodiment, there can be mentioned a thermal cross-linking agent covered with a thermally destructible hydrophilic coating material, and a thermal cross-linking agent in which a functional group is blocked by a protecting group dissociated by heat. These thermal crosslinking agents are described as lipophilic components microencapsulated in JP-A Nos. 7-1849, 7-1850, 9-311443, 10-6468, and 10-111168.

  The heat-meltable particles may be used in combination of several types such as different types and different particle sizes, and there is no particular limitation.

<Melting hot melt particles>
The time for melting the heat-meltable particles in the present invention is before laser exposure based on image information, and the method is not particularly limited, and is heated by a drying zone dryer warm air in the coating process after coating and drying, constant temperature. The method of heating in a tank etc. is mentioned.

  The heating temperature may be higher or lower than the melting point of the hot-melt particles, and may be high temperature short time or low temperature long time, but high temperature short time heating is preferable as workability.

  The melting of heat-meltable particles is defined as a particle that is completely melted and its shape is completely changed, or that it is partially melted and its shape is partially changed.

<Photothermal conversion material>
The lithographic printing plate material of the present invention preferably has a layer containing a photothermal conversion material.

  The layer having the photothermal conversion material is preferably an image forming layer or an adjacent layer thereof, and particularly preferably an image forming layer.

  An infrared absorbing dye or pigment can be used as the photothermal conversion material.

(Infrared absorbing dye)
Examples of infrared absorbing dyes include organic dyes such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, which are general infrared absorbing dyes. Examples thereof include compounds, phthalocyanine-based, naphthalocyanine-based, azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes.

  Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-280750, JP-A-1-293342, JP-A-2-2074, JP-A-3-26593, 3-30991, 3-34891, 3-36093, 3-36094, 3-36095, 3-42281, 3-97589, 3-103476, 7 -43851, 7-102179, JP-A-2001-117201, and the like. These can be used alone or in combination of two or more.

(Pigment)
Examples of the pigment include carbon, graphite, metal, metal oxide and the like.

  As carbon, it is particularly preferable to use furnace black or acetylene black. The particle size (d50) is preferably 100 nm or less, and more preferably 50 nm or less.

  As the graphite, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.

  As the metal, any metal can be used as long as the particle diameter is 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less. The shape may be any shape such as a spherical shape, a piece shape, or a needle shape. Colloidal metal fine particles (Ag, Au, etc.) are particularly preferable.

As the metal oxide, a material that is black in the visible light region or a material that is conductive or that is a semiconductor can be used. Examples of the material exhibiting black color in the visible light region include black iron oxide (Fe ₃ O ₄ ) and black mixed metal oxides containing two or more metals. Specifically, it is a composite metal oxide composed of two or more metals selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb, and Ba. These can be produced by the methods disclosed in JP-A-8-27393, 9-25126, 9-237570, 9-241529, and 10-231441. The composite metal oxide that can be used in the present invention is particularly preferably a Cu-Cr-Mn-based or Cu-Fe-Mn-based composite metal oxide. In the case of a Cu—Cr—Mn system, it is preferable to perform the treatment disclosed in JP-A-8-27393 in order to reduce the elution of hexavalent chromium.

  These composite metal oxides have good photothermal conversion efficiency. These composite metal oxides preferably have an average primary particle size of 1 μm or less, and more preferably have an average primary particle size in the range of 0.01 to 0.5 μm. When the average primary particle diameter is 1 μm or less, the photothermal conversion ability with respect to the addition amount becomes better, and when the average primary particle diameter is within the range of 0.01 to 0.5 μm, the photothermal conversion ability with respect to the addition amount is obtained. Better. However, the photothermal conversion ability with respect to the added amount is greatly affected by the degree of dispersion of the particles, and the better the dispersion, the better. Therefore, before adding these composite metal oxide particles to the coating solution, it is preferable to disperse them by a known method to prepare a dispersion (paste). An average primary particle size of less than 0.01 is not preferable because dispersion becomes difficult. A dispersing agent can be appropriately used for the dispersion. The addition amount of the dispersant is preferably 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass with respect to the composite metal oxide particles. Although the kind of dispersing agent is not specifically limited, it is preferable to use Si type surfactant containing Si element.

Examples of materials that have conductivity or are semiconductors include reduced Sb-doped SnO ₂ (ATO), Sn-added In ₂ O ₃ (ITO), TiO ₂ , and TiO ₂ . Examples thereof include TiO (titanium oxynitride, generally titanium black). Further, it is also possible to use those obtained by coating the core material _{(BaSO 4, TiO 2, 9Al} 2 O 3 · 2B 2 O, K 2 O · nTiO 2 , etc.) in these metal oxides. These particle sizes are 0.5 μm or less, preferably 100 nm or less, and more preferably 50 nm or less.

  A particularly preferable photothermal conversion material is a black complex metal oxide in which the infrared absorbing dye and the metal oxide are composed of two or more metal oxides.

  As addition amount of these photothermal conversion materials, it is 0.1-50 mass% with respect to the layer containing this, 1-30 mass% is preferable, and 3-25 mass% is more preferable.

<Polymerizable compound>
(Compound capable of addition polymerization by radical)
Although it does not specifically limit as a compound which can be addition-polymerized by a radical, For example, an ethylenically unsaturated polymerizable compound etc. are mentioned.

  The ethylenically unsaturated polymerizable compound preferably has a plurality of ethylenically unsaturated groups (bifunctional or more), and more preferably has 3 or more ethylenically unsaturated groups (trifunctional or more). It is preferably tetrafunctional or higher, more preferably pentafunctional or higher, and most preferably hexafunctional or higher.

  The ethylenically unsaturated polymerizable compound is preferably represented by the following general formula (I).

Formula (I)
L ₁ (−CR ₁ = CR ₂ R ₃ ) _m
In the general formula (I), L ₁ is an m-valent linking group, R ₁ , R ₂ and R ₃ are each independently a hydrogen atom, a halogen atom, an alkyl group or an aryl group, and m is It is an integer of 2 or more.

When m is 2, L ₁ is an alkylene group, a substituted alkylene group, an arylene group, a substituted arylene group, a divalent heterocyclic group, —O—, —S—, —NH—, —NR—, —CO—. , —SO—, —SO ₂ — and a combination thereof are preferably a divalent group. R is an alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group. The alkylene group and the alkyl group may have a cyclic structure or a branched structure.

  The number of carbon atoms in the alkylene group and the alkyl group is preferably 1 to 20, more preferably 1 to 15, still more preferably 1 to 10, and most preferably 1 to 8.

  Examples of the substituent of the substituted alkylene group and the substituted alkyl group include a halogen atom, an aryl group, a substituted aryl group and an alkoxy group.

  The arylene group is preferably phenylene, and most preferably p-phenylene. The aryl group is preferably phenyl.

  The divalent heterocyclic group may have a substituent.

  Examples of the substituent of the substituted arylene group, the substituted aryl group and the substituted heterocyclic group include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group and an alkoxy group.

When m is 3 or more, L ₁ represents a trivalent or higher aliphatic group, a trivalent or higher aromatic group, a trivalent or higher heterocyclic group, or an alkylene group, a substituted alkylene group, an arylene group, or a substituted arylene. A group, a divalent heterocyclic group, —O—, —S—, —NH—, —NR—, —N <, —CO—, —SO— or —SO ₂ — is preferable. R is an alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group.

  The trivalent or higher 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, still more preferably 1 to 10, and most preferably 1 to 8.

  The aliphatic group may have a substituent. Examples of the substituent include a halogen atom, an aryl group, a substituted aryl group, and an alkoxy group.

  The aromatic group is preferably a benzene ring residue. The aromatic group may have a substituent. Examples of the substituent include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, and an alkoxy group.

  The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group include a halogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, an alkoxy group, oxo (═O) and thio (═S).

L ₁ may constitute a main chain of a polymer composed of m repeating units.

R ₁ , R ₂ and R ₃ are each independently preferably a hydrogen atom, a halogen atom or an alkyl group, more preferably a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms. More preferably, it is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or methyl, and most preferably a hydrogen atom.

The linking group L _{1 in} the general formula (I) is a urethane bond (—NH—CO—O— or —NR—CO—O—, wherein R is an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group. ), A polymer image having excellent printing durability can be formed. Polymerizable compounds containing a urethane bond are described in JP-A-51-37193, JP-B-2-32293, and JP-A-2001-117217.

The linking group L ₁ of the general formula (I) may be a partial structure having liquid crystallinity. In other words, a liquid crystalline compound having an ethylenically unsaturated group (-CR ₁ = CR ₂ R _{3 in the} general formula (I)) can be used as the polymerizable compound. Liquid crystalline compounds having a polymerizable group are commonly used in the technical field of optical materials, particularly in the production of retardation plates and optical compensation sheets.

  The melting point of the liquid crystalline compound having an ethylenically unsaturated group is preferably 30 to 300 ° C, more preferably 50 to 270 ° C, still more preferably 70 to 240 ° C, and most preferably 90 to 210 ° C.

The ratio of the ethylenically unsaturated group contained in the liquid crystal compound is preferably 5.0 mmol or more, more preferably 7.0 mmol or more, per 1 g of the liquid crystal compound.
The liquid crystal compound is preferably a rod-like liquid crystal compound or a discotic liquid crystal compound. The liquid crystal compound may be a polymer liquid crystal.

  Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferred.

  The rod-like liquid crystal compound includes a metal complex. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystalline compound in a repeating unit can also be used as a rod-shaped liquid crystalline compound. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer.

  For rod-like liquid crystalline compounds, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemical Review Vol. 22 Liquid Crystal Chemistry (1994) edited by the Chemical Society of Japan, and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.

  The rod-like liquid crystalline compound preferably has two ethylenically unsaturated groups at both ends of the rod-like molecular structure.

  A discotic liquid crystal compound is more preferable than a rod-like liquid crystal compound. That is, the liquid crystal compound preferably has many ethylenically unsaturated groups. A discotic liquid crystalline compound (generally capable of introducing four or more ethylenically unsaturated groups) has more ethylene than a rod-like liquid crystalline compound (generally, the number of ethylenically unsaturated groups is two or less). It can have an unsaturated group.

  Examples of the discotic liquid crystalline compound include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), and azacrown and phenylacetylene macrocycles.

  A discotic liquid crystalline compound is a compound having a general molecular structure in which a linear alkyl group, an alkoxy group, or a substituted benzoyloxy group is substituted radially with respect to the mother nucleus at the center of the molecule. , Showing liquid crystallinity.

  Examples of the discotic liquid crystalline compound are described in JP-A-8-50206. The discotic liquid crystalline compound having a polymerizable group is described in JP-A-8-27284.

<Radical polymerization initiator>
(Compound that generates radicals by heat)
The compound that generates radicals by heat used in the image forming layer of the lithographic printing plate precursor according to the invention will be described.

  A compound that generates radicals by heat (hereinafter also referred to as a thermal radical generator) refers to a compound that generates radicals by thermal energy and initiates and accelerates polymerization of a compound having a polymerizable unsaturated group. As the thermal radical generator according to the present invention, a known thermal polymerization initiator or a compound having a bond with a small bond dissociation energy can be selected and used. For example, JP 2002-137562 A, JP 2001 2001 A -343742 and JP-A-2002-148790 include onium salts, triazine compounds having a trihalomethyl group, peroxides, azo polymerization initiators, azide compounds, quinonediazide compounds, metallocene compounds, and the like. However, the onium salts described below are preferred because of their high sensitivity.

  Examples of the onium salt suitably used as the thermal radical generator include a diazonium salt, an iodonium salt, a sulfonium salt, an ammonium salt, a pyridinium salt, and the like, and among them, an iodonium salt, a diazonium salt, a sulfonium salt, and the like are preferable. These onium salts also function as acid generators, but also function as initiators of ionic radical polymerization by another mechanism of action. An onium salt suitably used as a thermal radical generator is an onium salt represented by the following general formulas (II) to (IV), such as JP-A-2002-46361 and JP-A-2002-29162. The carboxylate ions and onium salts described in 1) are more preferred.

In general formula (II), Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms, which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a group having 12 or less carbon atoms. An aryloxy group is mentioned. Z ¹¹⁻ represents a counter ion selected from the group consisting of a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a sulfonate ion, and a carboxylate ion, preferably a perchlorate ion, a hexa Fluorophosphate ions, aryl sulfonate ions and carboxylate ions.

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

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

  In the present invention, onium salts represented by general formula (II) ([OI-1] to [OI-10]) and onium salts represented by general formula (III) ([ON-1]) that can be suitably used. To [ON-5]), and specific examples of the onium salts represented by the general formula (IV) ([OS-1] to [OS-6]) are shown below. The onium salts used in the present invention are: It is not limited to these.

  These onium salts as thermal radical generators are 0.1 to 50% by mass, preferably 0.5 to 30% by mass, particularly preferably 1 to 20%, based on the total solid content of the image forming layer of the lithographic printing plate precursor. It can be added at a rate of mass%. When the addition amount is 0.1% by mass or more, the sensitivity is further improved, and when the addition amount is 50% by mass or less, the non-image area is less likely to be smeared during printing.

  These onium salts as thermal radical generators may be used alone or in combination of two or more.

<binder>
A binder is used in the image forming layer of the lithographic printing plate precursor according to the invention.

  Any conventionally known binder can be used without particular limitation. It may be a hydrophobic polymer or a hydrophilic polymer.

  The main chain of the polymer may be selected from hydrocarbons (polyolefins), polyesters, polyamides, polyimides, polyureas, polyurethanes, polyethers and combinations thereof, with the main chain containing hydrocarbons or polyurethane being preferred. Examples of the polymer composed of the hydrocarbon main chain include poly (meth) acrylic acid, poly (meth) acrylic acid ester, poly (meth) acrylamide, poly (meth) acrylonitrile, polystyrene, polyvinyl acetal, and copolymers thereof.

  Various polymers used in the image forming layer are described in “POLYMER HANDBOOK”, FORTH EDITION, J. Pat. BRANDRUP, E.I. H. IMMERGUT, and E.I. A. Edited by GRULKE, JOHN WILEY & SONS, INC. There is a description.

<Thermal polymerization inhibitor>
In the present invention, in addition to the above basic components, a small amount of thermal polymerization is performed to prevent unnecessary thermal polymerization of a compound having an ethylenically unsaturated double bond that can be polymerized during production or storage of the imageable composition. An inhibitor may be added.

  Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2'-methylenebis (4-methyl-6-t-butylphenol), N-nitrosophenylhydroxyamine primary cerium salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the entire composition. In addition, if necessary, a higher fatty acid derivative such as behenic acid or behenic acid amide is added to prevent polymerization inhibition due to oxygen, and a lithographic printing plate precursor is dried after coating on a support or the like. In this process, it may be unevenly distributed on the surface of the image forming layer. The amount of the higher fatty acid derivative added is preferably about 0.5% by mass to about 10% by mass of the total composition.

<Support>
As the support, a metal plate, a plastic film or paper can be used. Specifically, a surface-treated aluminum plate, a hydrophilic-treated plastic film, or water-resistant treated paper is preferable. More specifically, an anodized aluminum plate, polyethylene terephthalate film provided with a hydrophilic layer, or paper laminated with polyethylene is preferable.

  An anodized aluminum plate is particularly preferred.

  The aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The proportion of the different element is preferably 10% by mass or less. A commercially available aluminum plate for a printing plate may be used.

  The thickness of the aluminum plate is preferably 0.05 to 0.6 mm, more preferably 0.1 to 0.4 mm, and most preferably 0.15 to 0.3 mm.

  It is preferable to perform a roughening treatment on the surface of the aluminum plate. The roughening treatment can be performed by a mechanical method, an electrochemical method, or a chemical method. As a mechanical method, a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be employed. As an electrochemical method, a method of performing alternating current or direct current in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid can be employed. An electrolytic surface roughening method using a mixed acid (described in JP-A-54-63902) can also be used. As a chemical method, a method of dipping an aluminum plate in a saturated aqueous solution of an aluminum salt of a mineral acid (described in JP-A No. 54-31187) is suitable.

  The roughening treatment is preferably performed so that the center line average roughness (Ra) of the surface of the aluminum plate is 0.2 to 1.0 μm.

  The roughened aluminum plate is subjected to an alkali etching treatment as necessary. As the alkali treatment liquid, an aqueous solution of potassium hydroxide or sodium hydroxide is generally used. After the alkali etching treatment, it is preferable to further carry out a neutralization treatment.

The anodizing treatment of the aluminum plate is performed in order to improve the wear resistance of the support. As the electrolyte used for the anodization treatment, 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 as the electrolyte. The treatment conditions for anodization are generally 1 to 80% by weight of electrolyte concentration, 5 to 70 ° C., a current density of 5 to 60 A / dm ² , a voltage of 1 to 100 V, and an electrolysis time of 10 seconds. The range is 5 minutes. The amount of the oxide film formed by the anodizing treatment is preferably 1.0 to 5.0 g / m ² , and more preferably 1.5 to 4.0 g / m ² .

  The oxide film formed by the anodizing treatment can be further subjected to a silicate treatment to form a hydrophilic surface. The treatment using an aqueous solution of an alkali metal silicate (eg, sodium silicate) is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734.

  The concentration of the alkali metal silicate in the aqueous solution is preferably 0.1 to 30% by mass, and more preferably 0.5 to 15% by mass. The pH of the aqueous solution at 25 ° C. is preferably 10 to 13.5. The temperature of the aqueous solution is preferably 5 to 80 ° C, more preferably 10 to 70 ° C, and further preferably 15 to 50 ° C. The treatment time is preferably 0.5 to 120 seconds. As a method for contacting the anodized film and the aqueous solution, spraying by dipping or spraying is preferable.

  The alkali metal serving as the counter ion of the silicate is preferably sodium, potassium or lithium. It is preferable to adjust the pH of the aqueous alkali metal silicate solution using a hydroxide (eg, sodium hydroxide, potassium hydroxide, lithium hydroxide). An alkaline earth metal salt or a Group IVb metal salt may be added to the aqueous solution. The alkaline earth metal salt is preferably water-soluble. Examples of alkaline earth metal salts include nitrates (eg, calcium nitrate, strontium nitrate, magnesium nitrate, barium nitrate), sulfate, hydrochloride, phosphate, acetate, oxalate and borate . Examples of Group IVb metal salts include titanium tetrachloride, titanium trichloride, potassium titanium fluoride, titanium potassium oxalate, titanium sulfate, titanium tetraiodide, and zirconium chloride oxide. Two or more alkaline earth metals or Group IVb metal salts may be used in combination. The addition amount of the alkaline earth metal or the Group IVb metal salt is preferably in the range of 0.01 to 10% by mass, and more preferably in the range of 0.05 to 5.0% by mass.

<Protective layer>
In the present invention, a protective layer may be provided on the image forming layer in order to protect the image forming layer and promote polymerization.

  The binder used for the protective layer can be used without any particular limitation.

  Binder resins include polyurethane, polyester, vinyl chloride resins such as vinyl chloride copolymers, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymers, polyolefin resins such as butadiene-acrylonitrile copolymers, polyvinyl Polyvinyl acetal resin such as butyral, cellulose resin such as nitrocellulose, styrene resin such as styrene-butadiene copolymer, acrylic resin such as polymethyl methacrylate, polyamide, phenol resin, epoxy resin, phenoxy resin, polyvinyl butyral And acetal resins such as polyvinyl acetoacetal and polyvinyl formal, and water-soluble resins such as polyvinyl alcohol and gelatin.

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

<Anchor layer>
In the lithographic printing plate precursor according to the invention, an anchor layer of a compound containing a polymerizable group is preferably provided on the support. When an anchor layer is used, the image recording layer is provided on the anchor layer. The anchor layer enhances the adhesion between the support and the image recording layer in the exposed area, and easily peels from the support of the image recording layer in the unexposed area. improves.

  As the anchor layer, specifically, a silane coupling agent having an addition-polymerizable ethylenic double bond reactive group described in JP-A-10-282679, JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of description are mentioned suitably. In addition, a compound having a polymerizable group such as a methacryl group or an allyl group and a support adsorbing group such as a sulfonic acid group, a phosphoric acid group or a phosphoric acid ester, and preferably a hydrophilic group such as an ethylene oxide group is also included. Is preferred.

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

<Printing method and image exposure>
The exposure light source for forming an image on the lithographic printing plate material of the present invention can be used without particular limitation as long as the light-to-heat conversion material can respond. Among them, in order to obtain a high resolution, an electromagnetic wave whose energy application area can be narrowed down, particularly an ultraviolet ray having a wavelength of 1 nm to 1 mm, a visible ray, and an infrared ray are preferable. As a light source capable of applying such light energy, for example, a laser, Light emitting diodes, xenon flash lamps, halogen lamps, carbon arc lamps, metal halide lamps, tungsten lamps, quartz mercury lamps, high pressure mercury lamps and the like can be mentioned. The energy applied at this time can be selected and used in a timely manner by adjusting the exposure distance, time, and intensity depending on the type of image forming material.

As laser light sources used in the printing method of the present invention, solid lasers such as ruby laser, YAG laser, and glass laser that are generally well known; He—Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser Gas lasers such as He-Cd laser, N ₂ laser, and excimer laser; semiconductor lasers such as InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, and GaSb laser; chemical laser, dye laser, etc. Among these, a laser having a wavelength of 6000 to 1200 nm is preferable in terms of sensitivity because it can convert light energy into heat energy.

<On-machine development>
The printing method of the present invention is characterized in that printing is performed without performing development processing after laser exposure based on image information.

  The on-press development in the present invention has the following contents.

  This is a method of removing the unexposed portion of the image forming layer of the lithographic printing plate material by mounting the exposed lithographic printing plate material on the cylinder of the printing press and supplying dampening water and ink while rotating the cylinder. .

  That is, after the lithographic printing plate material is exposed, it is mounted on a printing machine as it is, and the development process is completed in a normal printing process.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" is used in an Example, unless otherwise indicated, "mass part" is represented.

Example 1
[Support]
An aluminum plate made of material 1S having a thickness of 0.30 mm was used with a No. 8 nylon brush and an aqueous suspension of 800 mesh Pamiston, and its surface was grained and washed thoroughly with water. After etching by immersing in 10% sodium hydroxide at 70 ° C. for 60 seconds, washed with running water, neutralized with 20% HNO ₃ and washed with water. This was subjected to an electrolytic surface roughening treatment in a 1% nitric acid aqueous solution with a anodic electricity quantity of 300 coulomb / dm ² using a sinusoidal alternating current under the condition of VA = 12.7V. When the surface roughness was measured, it was 0.45 μm (Ra indication).

Next, after dipping in a 30% H ₂ SO ₄ aqueous solution and desmutting at 55 ° C. for 2 minutes, a cathode was placed on the grained surface in 33 ° C., 20% H ₂ SO ₄ aqueous solution to obtain a current density. When anodized at 5 A / dm ² for 50 seconds, the thickness was 2.7 g / m ² .

The following surface treatment intermediate layer (1) liquid composition was applied to this so that the Si amount was 2 mg / m ^2, and dried at 100 ° C. for 1 minute to obtain a support.

(Surface treatment intermediate layer (1) liquid composition)
Polyethylene glycol (number average molecular weight of about 1000) 96 parts by mass Methanol 100 parts by mass Water 14 parts by mass Phosphoric acid (85% aqueous solution) 11 parts by mass Tetraethoxysilane 36 parts by mass 3-Methacryloxypropyltrimethoxysilane 50 parts by mass << Lithographic printing Preparation of plate master 2 >>
[Anchor layer]
The following anchor layer coating solution was applied to the support by bar coating and dried to 120 g / m ² and dried at 120 ° C. for 1 minute to provide an anchor layer.

(Anchor layer coating solution)
Phosmer PE (Unichemical Co., Ltd.) 0.12 parts Isopropyl alcohol 99.88 parts [Image forming layer]
On the anchor layer, the following image forming layer coating solution 1 was applied by bar coating to 1.0 g / m ² after drying and dried at 70 ° C. for 1 minute to provide an image forming layer.

(Image forming layer coating solution 1)
Infrared dye ADS830AT (the following structure) 0.1328 parts Binder polymer BM-S (manufactured by Sekisui Chemical Co., Ltd.) 1.7221 parts Polymerizable compound M-315 (manufactured by Toagosei Co., Ltd.) (the following structure) 1.7221 parts Radical polymerization initiator (the following structure) 0.438 parts Opt-Bead 500S (Nissan Chemical Industry Co., Ltd.) 2.92 parts HI-DISPERA-118 (manufactured by Gifu Shellac Manufacturing Co., Ltd., heat melting particles, melting point 80 ° C.) 0 365 parts Methyl ethyl ketone 92.7 parts

[Protective layer]
On the image forming layer, the following protective layer coating solution was applied by bar coating and dried to 1.2 g / m ² and dried at 70 ° C. for 1 minute to provide an anchor layer.

(Protective layer coating solution)
GL-05 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 7.7 parts Pure water 92.3 parts The lithographic printing plate precursor prepared above is placed in a high-temperature bath at 120 ° C. for 1 minute, and heat melting in the image forming layer The lithographic printing plate precursor 1 was prepared by melting the conductive particles.

<< Preparation of lithographic printing plate precursor 2 >>
A lithographic printing plate precursor 2 was produced in the same manner as the lithographic printing plate precursor 1, except that the amount of the compound used in the image forming layer coating solution was changed as described below in the production of the lithographic printing plate precursor 1. .

(Image forming layer coating solution 2)
Infrared dye ADS830AT (supra) 0.073 parts Binder polymer BM-S (Sekisui Chemical Co., Ltd.) 1.7221 parts Polymerizable compound M-315 (Toagosei Co., Ltd.) (supra) 1.7221 parts Radical polymerization Initiator (supra) 0.1328 parts Optobead 500S (Nissan Chemical Industry Co., Ltd.) 2.92 parts HI-DISPERA-118 (Gifu Shellac Manufacturing Co., Ltd., heat-meltable particles, melting point 80 ° C.) 0.73 Methyl ethyl ketone 92.7 parts << Preparation of lithographic printing plate precursor 3 >>
A lithographic printing plate precursor 3 was produced in the same manner as the lithographic printing plate precursor 1, except that the amount of the compound used in the image forming layer coating solution was changed as described below in the production of the lithographic printing plate precursor 1. .

(Image forming layer coating solution 3)
Infrared dye ADS830AT (supra) 0.073 parts Binder polymer BM-S (Sekisui Chemical Co., Ltd.) 1.2045 parts Polymerizable compound M-315 (Toagosei Co., Ltd.) (supra) 1.2045 parts Radical polymerization Initiator (supra) 0.073 parts Optobead 500S (Nissan Chemical Industry Co., Ltd.) 4.38 parts HI-DISPERA-118 (manufactured by Gifu Shellac Manufacturing Co., Ltd., melting point of heat melting particles, 80 ° C.) 0.365 Methyl ethyl ketone 92.7 parts << Preparation of lithographic printing plate precursor 4 >>
A lithographic printing plate precursor 4 was produced in the same manner as the lithographic printing plate precursor 1, except that the amount of the compound used in the image forming layer coating solution was changed as described below in the production of the lithographic printing plate precursor 1. .

(Image forming layer coating solution 4)
Infrared dye ADS830AT (supra) 0.073 parts Binder polymer BM-S (Sekisui Chemical Co., Ltd.) 1.7221 parts Polymerizable compound M-315 (Toagosei Co., Ltd.) (supra). 7221 parts Radical polymerization initiator (supra) 0.1328 parts Snowtex-XS (Nissan Chemical Industry Co., Ltd.) 2.92 parts HI-DISPERA-118 (manufactured by Gifu Shellac Manufacturing Co., Ltd., melting point of hot-melt particles 80 ° C) 0.73 part Methyl ethyl ketone 92.7 parts << Preparation of lithographic printing plate precursor 5 >>
A lithographic printing plate precursor 5 was produced in the same manner as the lithographic printing plate precursor 1, except that the amount of the compound used in the image forming layer coating solution was changed as described below in the production of the lithographic printing plate precursor 1. .

(Image forming layer coating solution 5)
Infrared dye ADS830AT (supra) 0.073 parts Binder polymer BM-S (Sekisui Chemical Co., Ltd.) 1.7221 parts Polymerizable compound M-315 (Toagosei Co., Ltd.) (supra) 1.7221 parts Radical polymerization Initiator (supra) 0.1328 parts Snowtex-XS (Nissan Chemical Industry Co., Ltd.) 2.92 parts HI-DISPERA-514 (Gifu Shellac Manufacturing Co., Ltd., melting point of heat melting particles 115 ° C.) 0.73 parts Methyl ethyl ketone 92.7 parts <Preparation of lithographic printing plate precursor 6>
In the production of the lithographic printing plate precursor 1, the lithographic printing plate precursor 6 was prepared in the same manner as the lithographic printing plate precursor 1, except that the type and amount of the compound used in the coating solution for the image forming layer were changed as described below. Was made.

(Image forming layer coating solution 6)
Infrared dye ADS830AT (supra) 0.073 parts Binder polymer BM-S (Sekisui Chemical Co., Ltd.) 1.7221 parts Polymerizable compound M-315 (Toagosei Co., Ltd.) (supra) 1.7221 parts Radical polymerization Initiator (supra) 0.1328 parts Snowtex-XS (Nissan Chemical Industry Co., Ltd.) 2.92 parts ACRT2215F (Taisei Fine Chemical Co., Ltd., heat-meltable particles, melting point 70 ° C.)
0.73 parts Methyl ethyl ketone 92.7 parts << Preparation of planographic printing plate precursor 7 >>
In the production of the lithographic printing plate precursor 1, the lithographic printing plate precursor 7 was prepared in the same manner as the lithographic printing plate precursor 1, except that the type and amount of the compound used in the coating solution for the image forming layer were changed as described below. Was made.

(Image forming layer coating solution 7)
Infrared dye ADS830AT (supra) 0.1328 parts Binder polymer BM-S (Sekisui Chemical Co., Ltd.) 1.9018 parts Polymerizable compound M-315 (Toagosei Co., Ltd.) (supra) 1.9919 parts Radical polymerization Initiator (supra) 0.438 parts Optobead 500S (Nissan Chemical Industry Co., Ltd.) 2.92 parts HI-DISPERA-118 (Gifu Shellac Manufacturing Co., Ltd., heat melting particles, melting point 80 ° C.) 0.0146 Methyl ethyl ketone 92.7 parts << Preparation of lithographic printing plate precursor 8 >>
In the production of the lithographic printing plate precursor 1, the type and amount of the compound used in the image-forming layer coating solution were changed as described below, and “120 ° C. for 1 minute in a high-temperature bath and in the image-forming layer The lithographic printing plate precursor 8 was prepared in the same manner as the lithographic printing plate precursor 1 except that the above was not performed.

(Image forming layer coating solution 8)
Infrared dye ADS830AT (supra) 0.1328 parts Binder polymer BM-S (Sekisui Chemical Co., Ltd.) 1.9049 parts Polymerizable compound M-315 (Toagosei Co., Ltd.) (supra) 1.9049 parts Radical polymerization Initiator (supra) 0.438 parts Optobead 500S (Nissan Chemical Industry Co., Ltd.) 2.92 parts Methyl ethyl ketone 92.7 parts << Preparation of lithographic printing plate precursor 9 >>
In the preparation of the lithographic printing plate precursor 1, the same procedure as in the lithographic printing plate precursor 1 was carried out except that “there was not put into a high-temperature bath at 120 ° C. for 1 minute to melt the heat-meltable particles in the image forming layer”. Thus, a lithographic printing plate precursor 9 was prepared.

<< Preparation of planographic printing plate precursor 10 >>
In the production of the lithographic printing plate precursor 2, the same procedure as in the lithographic printing plate precursor 2 was carried out except that it was not put into a high-temperature bath at 120 ° C. for 1 minute to melt the heat-meltable particles in the image forming layer. Thus, a lithographic printing plate precursor 10 was prepared.

<< Preparation of planographic printing plate precursor 11 >>
A lithographic printing plate precursor 11 was produced in the same manner as the lithographic printing plate precursor 1, except that the amount of the compound used in the image forming layer coating solution was changed as described below in the production of the lithographic printing plate precursor 1. .

(Image forming layer coating solution 11)
Infrared dye ADS830AT (supra) 0.073 parts Binder polymer BM-S (manufactured by Sekisui Chemical Co., Ltd.) 1.022 parts Polymerizable compound M-315 (manufactured by Toagosei Co., Ltd.) (supra) 1.022 parts Radical polymerization initiator (supra) 0.438 parts Optobead 500S (Nissan Chemical Industry Co., Ltd.) 2.92 parts HI-DISPERA-118 (manufactured by Gifu Shellac Manufacturing Co., Ltd., heat melting particles, melting point 80 ° C.) 1 825 parts Methyl ethyl ketone 92.7 parts << Preparation of lithographic printing plate precursor 12 >>
A lithographic printing plate precursor 12 was produced in the same manner as the lithographic printing plate precursor 1, except that the amount of the compound used in the image forming layer coating solution was changed as described below in the production of the lithographic printing plate precursor 1. .

Infrared dye ADS830AT (supra) 0.073 parts Binder polymer BM-S (manufactured by Sekisui Chemical Co., Ltd.) 1.022 parts Polymerizable compound M-315 (manufactured by Toagosei Co., Ltd.) (supra) 1.022 parts Radical polymerization initiator (supra) 0.438 parts Optobead 500S (Nissan Chemical Industry Co., Ltd.) 2.19 parts HI-DISPERA-118 (manufactured by Gifu Shellac Manufacturing Co., Ltd., heat melting particles, melting point 80 ° C.) 2 555 parts Methyl ethyl ketone 92.7 parts << Evaluation method >>
<Exposure and printing of planographic printing plate precursor>
(Exposure method)
Using the obtained lithographic printing plate precursor, a semiconductor laser light source (light emission wavelength: 830 nm, spot size: 10 μm, resolution is 2000 dpi in both the scanning direction and the sub-scanning direction), a 175-line equivalent 50% dot image and a solid image, Exposure was performed by changing the amount of irradiation energy on the image plane while changing the scanning speed.

  In addition, dpi represents the number of dots per 2.54 cm.

(Printing method)
The exposed lithographic printing plate precursor is attached to a Heidel GTO printing machine without developing, and 45 times water diluted solution of SEU-3 (manufactured by Konica Co., Ltd.) as an etchant and HiEcho (Toyo Ink Co., Ltd.) as an ink. )), And printing was performed using high-quality paper as printing paper.
Printing was performed in an environment of 23 degrees 48%.

<sensitivity>
The exposure energy at which a fine line of 4000 dpi lines and spaces was completely reproduced on the printed matter was determined. The lower the exposure energy, the higher the sensitivity.

<Number of damaged paper (on-press developability)>
The number of damaged paper sheets (on-machine developability) until the finished quality of the printed matter with a halftone dot image of 50% was practically usable and became good was determined by visual observation. A smaller number of sheets is better with less waste paper.

<Press life>
The number of prints on which 50% halftone dots were not reproduced was determined by visual observation. The larger the number, the higher the printing durability and the better.

  The results are shown in Table 1.

  From Table 1, in the case of the present invention, the number of lost paper in the printed halftone image is small and stable, the quality is also stable and excellent on-press developability, and the sensitivity and printing durability are also excellent. It turns out that it is stable.

Claims (8)

It has an image recording layer having a polymerizable compound, a radical polymerization initiator, and heat-meltable particles on a support, and the heat-meltable particles are melted before the exposure after coating the image-recording layer. Planographic printing plate precursor. 2. The lithographic printing plate according to claim 1, wherein 0.25 mass% ≦ A <30 mass%, where A (mass%) is an addition mass fraction of the heat-fusible particles in the image recording layer. Original edition. The lithographic printing plate precursor as claimed in claim 1 or 2, wherein the heat-meltable particles are wax. 4. A printing method comprising printing the lithographic printing plate precursor according to claim 1, 2 or 3 by laser exposure based on image information and performing on-press development processing. It has an image recording layer having a polymerizable compound, a radical polymerization initiator, and heat-meltable particles on a support, and the heat-meltable particles are melted before the exposure after coating the image-recording layer. A method for producing a lithographic printing plate precursor. 6. The lithographic printing plate according to claim 5, wherein 0.25 mass% ≦ A <30 mass%, where A (mass%) is an addition mass fraction of the heat-fusible particles in the image recording layer. Production method of the original plate. The method for producing a lithographic printing plate precursor as claimed in claim 5 or 6, wherein the heat-meltable particles are wax. A printing method comprising: printing a lithographic printing plate precursor produced by the lithographic printing plate precursor production method according to claim 5, 6 or 7 by laser exposure based on image information and performing on-press development processing.