JP2007136938A - Lithographic printing plate material, method for preparing lithographic printing plate and method for processing lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate material having on-machine developing properties, good sensitivity, good scuff resistance, and good handling properties. <P>SOLUTION: In the lithographic printing plate material having an image forming layer comprising a hot-melt particle, at least one compound selected from a polymerizable monomer with an unsaturated ethylene group and a polymerizable prepolymer, and a polymerization initiator on a hydrophilic substrate, the polymerization starting temperature T1 with at least one compound selected from the polymerizable monomer with the unsaturated ethylene group and the polymerizable prepolymer, and the polymerization initiator is higher than the melting point T2 of the hot-melt particle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate material and a method for producing a lithographic printing plate using the lithographic printing plate material.

  In recent years, in synchronization with the spread of computers, CTP technology that directly inputs images to the PS plate using a semiconductor laser via a computer based on digital image data is also used in printing plate technology in terms of process simplification and cost. Has attracted attention. In addition, the progress of so-called processless CTP technology, which does not require processing with a developing solution, is progressing as environmental problems and office space are reduced.

  Among these technologies, for practical use in recent years, a heat-sensitive layer containing hot-melt particles dispersed with a hydrophilic resin was laminated on a hydrophilic support for printing, as the technology was highly complete. And lithographic printing plate materials. In this technology, the heat-sensitive layer is imagewise exposed with a semiconductor laser, etc., and the heat-meltable particles in the laser-irradiated part are melted and fixed by adhering to the hydrophilic support, and the part not irradiated with laser is printed. It is a so-called on-press development type lithographic printing plate material that is developed by being removed by an ink roller, a dampening water roller or a blanket. (For example, see Patent Documents 1 and 2) According to these techniques, the on-press developability and image strength (printing durability) are affected by the hydrophilic resin content, and the on-press developability and image strength It was difficult to achieve high balance.

  A lithographic printing plate material is disclosed in which an organic base or an inorganic salt is contained in a heat-sensitive layer containing heat-meltable particles in order to ensure on-press developability. (For example, refer to Patent Documents 3 and 4) According to these, since the organic base and inorganic salt remaining in the image portion coating film by exposure are excluded from the coating film during printing, the strength of the image portion is maintained. Although the deterioration of the printing durability is reduced, it is insufficient for maintaining the image strength. Moreover, an organic base and an inorganic salt inhibit the fusion | melting of a heat-meltable particle, and a sensitivity will fall.

  As described above, in order to ensure developability on a printing press, when measures are taken to ensure developability, it was difficult to maintain and improve printing durability.

Further, in order to improve printing durability, a lithographic printing plate material in which a heat-sensitive layer containing heat-fusible particles dispersed by a hydrophilic resin is laminated on a printing hydrophilic support, which is crosslinked to the heat-sensitive layer Examples containing the agent are described. (For example, see Patent Document 5) According to this example, it is possible to improve the image strength while ensuring developability on a printing press, but the effect is not sufficient. Moreover, the fall of the sensitivity was seen depending on the kind of hardening | curing agent.
Japanese Patent No. 293888397 Japanese Patent No. 293897 Special table 2004-522625 gazette Japanese translation of PCT publication No. 2004-522991 JP-A-10-128945

  The present invention has been made in view of the above circumstances, and an object of the present invention is a lithographic printing plate material having on-machine developability, good sensitivity and scratch resistance, good handleability, and lithographic printing using the same It is to provide a method for producing a plate.

  The above object of the present invention is achieved by the following configurations.

  1. A lithographic printing plate material having an image forming layer containing at least one compound selected from a heat-meltable particle, a polymerizable monomer having an unsaturated ethylene group and a polymerizable prepolymer on a hydrophilic support, and a polymerization initiator The polymerization start temperature T1 by at least one compound selected from the polymerizable monomer having an unsaturated ethylene group and the polymerizable prepolymer and a polymerization initiator is higher than the melting point T2 of the hot-melt particles. Lithographic printing plate material to do.

  2. The difference between the polymerization start temperature T1 by the at least one compound selected from the monomer having an unsaturated ethylene group and the polymerizable prepolymer and the polymerization initiator and the melting point T2 of the hot-melt particles is 10 to 50 ° C. or less. 2. The lithographic printing plate material as described in 1 above.

  3. 3. The lithographic printing plate material as described in 1 or 2 above, wherein at least one compound selected from a polymerizable monomer having an unsaturated ethylene group and a polymerizable prepolymer is water-soluble.

  4). 4. The lithographic printing plate material as described in any one of 1 to 3 above, wherein the content of the heat-fusible particles in the image forming layer is 60% by mass or less.

  5. The lithographic printing plate material according to any one of 1 to 4 above, a temperature higher than a polymerization initiation temperature T1 by at least one compound selected from a monomer having an unsaturated ethylene group and a polymerizable prepolymer and a polymerization initiator. A method for producing a lithographic printing plate, characterized by drawing with

  6). The lithographic printing plate material image-drawn by the method of preparing a lithographic printing plate as described in 5 above is mounted on a cylinder of a printing machine, and then developed while supplying dampening water and printing ink. Plate processing method.

  The lithographic printing plate material according to the present invention and the method for producing a lithographic printing plate using the lithographic printing plate material have excellent on-machine developability, good sensitivity and scratch resistance, good handleability and excellent effects.

  Hereinafter, embodiments of the present invention will be described.

  The lithographic printing plate material of the present invention comprises an image forming layer containing, on a hydrophilic support, at least one compound selected from hot melt particles, a polymerizable monomer having an unsaturated ethylene group, and a prepolymer, and a polymerization initiator. have.

Polymerizable monomer / prepolymer having an unsaturated ethylene group The photopolymerizable compound used in the present invention contains at least a monomer / prepolymer having an ethylenically unsaturated bond that can be polymerized with active light.

Examples of the photopolymerizable monomer / prepolymer include monofunctional acrylic acid esters such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and derivatives thereof, or acrylates thereof such as methacrylate, itaconate, crotonate, Compound substituted for maleate, etc., polyethylene glycol diacrylate, pentaerythritol diacrylate, bisphenol A diacrylate, bifunctional acrylic acid ester such as diacrylate of ε-caprolactone adduct of neopentyl glycol hydroxypivalate and its derivatives or their derivatives Compounds in which acrylate is replaced with methacrylate, itaconate, crotonate, maleate, etc., or trimethylolpropane tri (meth) a Examples include polyfunctional acrylic esters such as relates, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pyrogallol triacrylate and derivatives thereof, or compounds in which these acrylates are replaced with methacrylate, itaconate, crotonate, maleate, etc. . As the resin having an ethylenically unsaturated bond, a so-called prepolymer in which acrylic acid or methacrylic acid is introduced into an oligomer having an appropriate molecular weight to impart polymerizability can be suitably used. Other preferable photopolymerizable compounds include compounds described in JP-A Nos. 61-6649 and 62-173295, compounds described in JP-A-2005-41206 (0085) to (0097), “11290 “Chemical Products”, Chemical Industry Daily, p. Compounds described in 286 to 294, “UV / EB Curing Handbook (raw material)”, Kobunshi Publishing Co., Ltd., p. The compounds described in 11 to 65 can be preferably used in the present invention.
The above polymerizable monomer / prepolymer has hydrophilic properties such as carboxyl group, sulfonic acid group, phosphoric acid, amino group or salts thereof, hydroxyl group, amide group and ether group in order to facilitate developability on a printing press. It is more preferable to modify the functional group having the property to make it water-soluble.

Polymerization initiator The polymerization initiating material of the present invention generates radicals by light and / or heat, and initiates the curing reaction of the aforementioned photopolymerization compound. In the present invention, a photopolymerization initiating material or a thermal polymerization initiating material is used. In the present invention, since a photothermal conversion agent is used in combination, a thermal polymerization initiating material that decomposes by heat to generate radicals is preferably used.

  As a polymerization initiation material of the present invention, an onium salt, a triazine compound having a halogen atom (such as triazine derivatives described in JP-B-59-1281, 61-9621, and JP-A-60-60104), an iron arene complex And bisimidazoles (such as 2,4,5-triarylimidazole dimers described in JP-A Nos. 55-127550 and 60-202437) are preferably used.

  Examples of the onium salt include an iodonium salt, a sulfonium salt, a phossonium salt, a stannonium salt, an oxazolium salt, and the like, preferably represented by the following general formula (I), (II), (III), or (IV) A compound.

In the general formula (I), (II), (III) or (IV), R _{1 to} R ₄ and R _{10 to} R ₁₃ each represents an alkyl group, an aryl group or an aralkyl group, and R _{1 to} R ₄ and R _{10 to} R ₁₃ may be bonded to each other to form a ring. R ₅ , R ₆ and R ₇ each represents an alkyl group or an aryl group, and R _{5 to} R ₇ may be bonded to each other to form a ring. R8 and R9 each represents an aryl group, and X ⁻ represents a counter anion.

  First, the phosphonium salt compound represented by the general formula (I) (hereinafter referred to as the phosphonium salt of the present invention) will be described in detail.

Specific examples of the substituent represented by R _{1 to} R ₄ are as follows.

  Alkyl groups include straight-chain and branched alkyl groups such as methyl, ethyl, butyl, i-butyl, hexyl, octyl, stearyl groups and the like. From the viewpoint of color density, an alkyl group having 1 to 10 carbon atoms is preferable, and a butyl group is particularly preferable. These alkyl groups may be bonded to each other to form a ring, and the cycloalkyl group is preferably a 5- to 7-membered ring (for example, cyclopentyl, cyclohexyl group, etc.).

  Examples of the aryl group include phenyl and naphthyl groups, and examples of the aralkyl group include benzyl and phenethyl groups.

  These groups may be further substituted, and as a substituent, a halogen atom, a cyano group, a nitro group, an alkyl group, an aryl group, a hydroxyl group, an amino group (including an alkyl-substituted amino group), an alkoxy group, a carbamoyl group, -COOR group and -OCOR group (R is an organic group such as an alkyl group and an aryl group).

The counter anion represented by X ⁻ is not particularly limited as long as it is a monovalent anion, but is preferably a halogen ion, and chlorine and bromine anions are more desirable in terms of color density. Specific examples of the counter anion include bromide, chloride, iodide, fluoride, perchlorate, benzoate, thiocyanate, acetate, trifluoroacetate, hexafluorophosphate, nitrate, salicinate and the like.

  Next, the sulfonium salt compound represented by the general formula (II) (hereinafter referred to as the sulfonium salt of the present invention) will be described in detail.

Specific examples of the substituent represented by R _{5 to} R ₇ are as follows.
Alkyl groups include linear and branched alkyl groups, and include methyl, ethyl, butyl, i-butyl, hexyl, octyl, stearyl groups and the like. From the viewpoint of color density, an alkyl group having 1 to 10 carbon atoms is preferable, and a butyl group is particularly preferable. These alkyl groups may be bonded to each other to form a ring, and the cycloalkyl group is preferably a 5- to 7-membered ring (for example, cyclopentyl, cyclohexyl group, etc.).

  Examples of the aryl group include phenyl and naphthyl.

Examples of the ring formed by combining R _{5 to} R ₇ together with S ⁺ include a benzothiathiopyrylium ring.

  These groups may be further substituted, and examples of the substituent include the same groups as those described in the general formula (I).

X ^- counter anion represented by, X of the general Formulas (I) ^- is synonymous.
Furthermore, the iodonium salt compound represented by the general formula (III) (hereinafter referred to as the iodonium salt of the present invention) will be described in detail.

Examples of the aryl group represented by R ₈ and R ₉ include phenyl and naphthyl groups. These groups may be further substituted, and examples of the substituent include the groups described in the general formula (I). The same group is mentioned.

X ^- counter anion represented by, X of the general Formulas (I) ^- is synonymous.

  Next, the ammonium salt compound represented by the general formula (IV) (hereinafter referred to as the ammonium salt of the present invention) will be described in detail.

Specific examples of the substituent represented by R _{10 to} R ₁₃ are as follows.
Alkyl groups include straight-chain and branched alkyl groups such as methyl, ethyl, butyl, i-butyl, hexyl, octyl, stearyl and the like. From the viewpoint of color density, an alkyl group having 1 to 10 carbon atoms is preferable, and a butyl group is particularly preferable. These alkyl groups may be bonded to each other to form a ring, and the cycloalkyl group is preferably a 5- to 7-membered ring (for example, cyclopentyl, cyclohexyl group, etc.).

Examples of the aryl group include phenyl and naphthyl groups, and examples of the aralkyl group include benzyl and phenethyl groups.
These groups may be further substituted, and as a substituent, a halogen atom, cyano group, nitro group, alkyl group, aryl group, hydroxyl group, amino group (including alkyl-substituted amino group), alkoxy group, carbamoyl group , -COOR group, and -OCOR (wherein R represents an organic group such as an alkyl group or an aryl group).

  Examples of onium salts that can be used in the present invention are listed below, but the present invention is not limited thereto.

  Other preferable onium salts include various oniums described in JP-B-55-39162, JP-A-59-14023, and “Macromolecules”, Vol. 10, page 1307 (1977). Compounds.

The addition amount of the onium salt of the present invention is preferably 0.2 to 5 g per 1 m ^{2 of} the image forming material, although it varies depending on the kind of onium salt and the usage form.
Examples of the iron arene complex include the following structures.

In the formula, R ₁ represents an alkyl group, an aryl group or an alkoxy group.
Preferably it is compound (1) -1.

Compound (1) -1
Moreover, it is preferable to use the thing of the following structure as a bisimidazole compound.

  Of these polymerization starting materials, onium salts are particularly preferred.

  These polymerization initiating materials can be used in combination with other radical generators for the purpose of further improving the sensitivity. Examples of radical generators that can be used in combination are described in JP-A Nos. 59-1504 and 61-243807. Organic peroxides described in JP-B Nos. 43-23684, 44-6413, 44-6413, 47-1604 and U.S. Pat. No. 3,567,453, U.S. Pat. , 848,328, 2,852,379 and 2,940,853, JP-B 36-22062, 37-13109, 38-18015, and 45- Ortho-quinonediazides described in 9610, azo compounds described in JP-A-59-142205, JP-A-1-54440, European Patent 109, 51, 126,712, Journal of Imaging Science (J. Imag. Sci.), Volume 30, page 174 (1986), other metal arene complexes, (Oxo) sulfonium organoboron complexes described in JP-A Nos. 4-56831 and 4-89535, titanocenes described in JP-A No. 61-151197, “Coordination Chemistry Review”, Vol. 84, 85-277 (1988) and transition metal complexes containing transition metals such as ruthenium described in JP-A-2-182701, carbon tetrabromide described in JP-A-3-209477, JP-A 59- And the organic halogen compounds described in No. 107344.

  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 lithographic printing plate precursor can be handled under white light.

  In the present invention, the polymerization start temperature T1 by the polymerizable monomer and / or prepolymer or polymerization initiator having an unsaturated ethylene group is preferably 80 ° C. or higher and 200 ° C. or lower. If it is less than 80 ° C., the polymerization reaction proceeds during storage, and the developability on the printing press tends to deteriorate. Moreover, when it exceeds 200 degreeC, the fall of a laser exposure sensitivity and deterioration of image durability will be seen.

  The polymerization initiation temperature can be variously selected depending on the selected polymerizable monomer, prepolymer and polymerization initiator combination, but the approximate polymerization initiation temperature can be adjusted by the decomposition temperature of the polymerization initiator.

  The melting temperature can be determined from the peak of the endothermic temperature by using a differential thermal balance (TG-DTA) analyzer ThermoPlus2 (manufactured by Rigaku Denki Kogyo) for a mixture of a polymerizable monomer and / or a prepolymer and a polymerization initiator.

Heat-meltable particle In the present invention, the heat-meltable particle refers to a heat-meltable substance or a particulate material of a thermoplastic resin. As the hot-melt material, the waxes include carnauba wax, beeswax, whale wax, wood wax, jojoba oil, lanolin, ozokerite, paraffin wax, montan wax, candelin wax, ceresin wax, microcrystalline wax, rice wax. And natural waxes such as polyethylene wax, FT wax, Fischer-Tropsch wax, montan wax derivative, paraffin wax derivative, microcrystalline wax derivative, higher fatty acid and the like.

  In addition, as thermoplastic resins, synthesis of diene polymers such as polypropylene, polybutadiene, polyisoprene and ethylene-butadiene copolymers, styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers, acrylonitrile-butadiene copolymers, etc. Examples include (meth) acrylic acid ester copolymers, polystyrene, polyvinyl chloride, polyesters, polyurethanes, etc., which contain rubbers, methyl methacrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile and the like as constituent components.

  Among these, carnauba wax and (meth) acrylic acid ester-styrene copolymers have thermal responsiveness (low melt viscosity when heated) and hardness at room temperature, and have laser exposure sensitivity, resolution and image durability. Are better.

  A known method can be used as a method for making a heat-meltable substance or a thermoplastic resin into fine particles. Examples of chemical methods include emulsion polymerization, suspension polymerization, solution polymerization, and gas phase polymerization. As a physical method, a method in which a heat-meltable substance or a thermoplastic resin is heated and melted and stirred strongly in a solvent together with a surfactant, a pH adjuster, or the like can be used.

  The average particle diameter of the heat-fusible particles is preferably 0.02 to 2 μm, more preferably 0.05 to 0.8 μm. If it is smaller than this range, water developability and developability using dampening water and / or printing ink on the printing press deteriorate, and if it exceeds this range, laser exposure sensitivity and image durability deteriorate. It can be seen.

  In the present invention, the melting point T2 of the heat-meltable particles is preferably 80 ° C. or higher and 150 ° C. or lower. When the temperature is lower than 80 ° C., the fusion of the heat-meltable fine particles gradually proceeds during storage, and the developability on the printing press tends to deteriorate. On the other hand, when the temperature exceeds 150 ° C., the laser exposure sensitivity is lowered and the image durability is deteriorated.

  The melting point can be determined from the peak of the endothermic temperature by using a differential thermal balance (TG-DTA) analyzer ThermoPlus2 (manufactured by Rigaku Denki Kogyo Co., Ltd.) for the dried thermomeltable fine particles.

  In the present invention, the content of the heat-meltable particles in the image forming layer is preferably 60% by mass or less. If it exceeds 60% by mass, the fusion of the heat-meltable particles proceeds due to the pressure, and the developability on the printing press tends to be deteriorated or background stains tend to occur.

  The relationship between the polymerization start temperature T1 due to the polymerizable monomer and / or prepolymer and polymerization initiator and the melting point T2 of the thermally fusible particles is that the polymerization start temperature T1 due to the polymerizable monomer and / or prepolymer and polymerization initiator is hot meltable. It is preferable that the melting point T2 of the particles is higher. This relationship is necessary for the efficient fusion of the heat-meltable particles and the polymerization reaction of the polymerizable composition comprising the polymerizable monomer and / or prepolymer and the polymerization initiator. If it is out of this relationship, the fusion of the heat-meltable particles is hindered by the polymerization of the polysynthetic composition, and sufficient image strength cannot be obtained.

  Furthermore, the difference between T1 and T2 is preferably 10 to 50 ° C. Within this range, the efficiency of the fusion of the heat-meltable particles and the polymerization reaction by the polymerizable composition is further improved, and the printing durability is greatly improved.

Photothermal Conversion Material The image forming layer of the present invention preferably contains a converted photothermal conversion material that absorbs electromagnetic waves and generates heat. Examples of the photothermal conversion agent include infrared absorbing dyes, pigments, metals, and metal oxides.

  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.

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

  As carbon, furnace black or acetylene black is particularly preferable. 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 of the aforementioned metals. The metal oxide is a black complex metal oxide composed of two or more kinds of metal oxides. 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 are colored with respect to the amount added, that is, 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 addition amount is greatly affected by the degree of dispersion of the particles, and the better the dispersion, the better.

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 embodiment of the photothermal conversion material is that the infrared absorbing dye and the metal oxide are black complex metal oxides composed of two or more metal oxides.

  The content of these photothermal conversion agents in the image forming layer is preferably 1 to 20% by mass.

Water-soluble resin The image forming layer of the present invention may contain a water-soluble resin for imparting film properties and controlling developability on a printing press. Water-soluble resins that can be used in the present invention include water-soluble (co) polymers such as synthetic homo- or copolymers such as polyvinyl alcohol, poly (meth) acrylic acid, poly (meth) acrylamide, and polyhydroxyethyl (meth) acrylate. , Polyvinyl methyl ether, or natural binders such as gelatin, polysaccharides such as dextran, pullulan, cellulose, gum arabic, arginic acid, polyethylene glycol, polyethylene oxide and the like can be used. The preferred content is 0 to 40% by mass.

Next, the hydrophilic support used in the present invention will be described.

  As the hydrophilic support that can be used in the present invention, an aluminum substrate made of aluminum or an aluminum alloy (hereinafter also referred to as aluminum) is used because of the relationship between specific gravity and rigidity. Various aluminum alloys can be used. For example, an alloy of a metal such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium, iron, and aluminum is used. The thickness of the aluminum substrate is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.

  The aluminum substrate used in the present invention is more preferably one that has been subjected to any of the known roughening treatment, anodizing treatment, or surface hydrophilization treatment, that is, aluminum grain. The aluminum grain may be produced by any method, but one of the production methods for obtaining the surface shape defined in the present invention is the method disclosed in JP-A-10-869. Can do.

  The aluminum substrate according to the present invention is preferably subjected to a degreasing treatment in order to remove the rolling oil on the surface prior to roughening (graining treatment). As the degreasing treatment, a degreasing treatment using a solvent such as trichlene or thinner, an emulsion degreasing treatment using an emulsion such as kesilon or triethanol, or the like is used. In addition, an alkaline aqueous solution such as caustic soda can be used for the degreasing treatment. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, dirt and oxide film that cannot be removed only by the degreasing treatment can be removed. When an alkaline aqueous solution such as caustic soda is used for the degreasing treatment, smut is generated on the surface of the aluminum base material. In this case, it is immersed in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid thereof. It is preferable to perform a desmut treatment.

Examples of the roughening method include a mechanical method and a method of etching by electrolysis. The mechanical roughening method used is not particularly limited, but a brush polishing method and a honing polishing method are preferable. The roughening by the brush polishing method is, for example, by rotating a rotating brush using brush bristles having a diameter of 0.2 to 0.8 mm, and watering, for example, volcanic ash particles having a particle size of 10 to 100 μm on the surface of the aluminum substrate. While supplying the slurry dispersed uniformly, the brush can be pressed. The roughening by honing polishing is performed by, for example, uniformly dispersing volcanic ash particles having a particle size of 10 to 100 μm in water, injecting the pressure from a nozzle and injecting it obliquely to the surface of the aluminum base material. be able to. Also, for example, abrasive particles having a particle diameter of 10 to 100 μm are present on the surface of the aluminum substrate at a density of 2.5 × 10 ³ to 10 × 10 ³ particles / cm ² at intervals of 100 to 200 μm. Roughening can also be performed by laminating the coated sheets and transferring the rough surface pattern of the sheet by applying pressure.

After roughening by the above-mentioned mechanical roughening method, it is preferable to immerse in an aqueous solution of acid or alkali in order to remove the abrasive that has digged into the surface of the aluminum substrate, formed aluminum scraps and the like. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an aqueous alkali solution such as sodium hydroxide. The dissolution amount of aluminum in the support surface, 0.5 to 5 g / m ² is preferred. After the immersion treatment with an alkaline aqueous solution, it is preferable to carry out a neutralization treatment by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

The electrochemical surface roughening method is not particularly limited, but a method of electrochemical surface roughening in an acidic electrolyte is preferable. As the acidic electrolytic solution, an acidic electrolytic solution usually used in an electrochemical surface roughening method can be used, but a hydrochloric acid-based or nitric acid-based electrolytic solution is preferably used. As the electrochemical surface roughening method, for example, methods described in Japanese Patent Publication No. 48-28123, British Patent No. 896,563 and Japanese Patent Laid-Open No. 53-67507 can be used. This roughening method can be generally performed by applying a voltage in the range of 1 to 50 volts, but is preferably selected from the range of 10 to 30 volts. Current density may be in the range of 10 to 200 A / dm ^2, preferably selected from the range of 50 to 150 A / dm ^2. The quantity of electricity, may be in the range of 5000 C / dm ^2, preferably selected from the range of 100~2000c / dm ^2. The temperature at which the roughening method is performed can be in the range of 10 to 50 ° C, but is preferably selected from the range of 15 to 45 ° C.

When electrochemical surface roughening is performed using a nitric acid-based electrolyte as the electrolyte, it can be generally performed by applying a voltage in the range of 1 to 50 volts, but is selected from the range of 10 to 30 volts. Is preferred. Current density may be in the range of 10 to 200 A / dm ^2, preferably selected from the range of 20 to 100 A / dm ^2. The quantity of electricity, may be in the range of 5000 C / dm ^2, preferably selected from the range of 100~2000c / dm ^2. The temperature at which the electrochemical roughening method is performed can be in the range of 10 to 50 ° C, but is preferably selected from the range of 15 to 45 ° C. The concentration of nitric acid in the electrolytic solution is preferably 0.1 to 5% by mass. If necessary, nitrates, chlorides, amines, aldehydes, phosphoric acid, chromic acid, boric acid, acetic acid, oxalic acid, and the like can be added to the electrolytic solution.

When a hydrochloric acid-based electrolyte is used as the electrolyte, it can be generally applied by applying a voltage in the range of 1 to 50 volts, but is preferably selected from the range of 2 to 30 volts. Current density may be in the range of 10 to 200 A / dm ^2, preferably selected from the range of 50 to 150 A / dm ^2. The quantity of electricity, may be in the range of ^{100~5000c / dm 2, 100~2000c / dm} 2, and more preferably selected from the range of 200~1000c / dm ^2. The temperature at which the electrochemical roughening method is performed can be in the range of 10 to 50 ° C, but is preferably selected from the range of 15 to 45 ° C. The concentration of hydrochloric acid in the electrolytic solution is preferably 0.1 to 5% by mass.

After the surface is roughened by the electrochemical surface roughening method, it is preferably immersed in an acid or alkali aqueous solution in order to remove aluminum scraps on the surface. Examples of the acid include sulfuric acid, persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid, hydrochloric acid, and the like. Examples of the base include sodium hydroxide and potassium hydroxide. Among these, it is preferable to use an alkaline aqueous solution. The dissolution amount of aluminum in the support surface, 0.5 to 5 g / m ² is preferred. In addition, it is preferable that after the immersion treatment with an alkaline aqueous solution, neutralization treatment is performed by immersion in an acid such as phosphoric acid, nitric acid, sulfuric acid, chromic acid or a mixed acid thereof.

  The mechanical surface roughening method and the electrochemical surface roughening method may each be used alone for roughing, or the mechanical surface roughening method followed by the electrochemical surface roughening method. You may roughen.

Following the roughening treatment, anodizing treatment is preferably performed. There is no restriction | limiting in particular in the method of the anodizing process which can be used in this invention, A well-known method can be used. By performing the anodizing treatment, an oxide film is formed on the aluminum substrate. For the anodizing treatment, a method of electrolyzing an aqueous solution containing sulfuric acid and / or phosphoric acid at a concentration of 10 to 50% as an electrolytic solution at a current density of 1 to 10 A / dm ² is preferably used. A method of electrolysis at a high current density in sulfuric acid described in Japanese Patent No. 1,412,768, a method of electrolysis using phosphoric acid described in US Pat. No. 3,511,661, chromium Examples thereof include a method using a solution containing one or more acids, oxalic acid, malonic acid and the like. The formed anodic oxidation coating amount is suitably 1 to 50 mg / dm ² , preferably 10 to 40 mg / dm ² . The amount of anodic oxidation coating is, for example, by immersing an aluminum plate in a chromic phosphate solution (85% phosphoric acid solution: 35 ml, prepared by dissolving 20 g of chromium (IV) oxide in 1 L of water) to dissolve the oxide layer, It is obtained from mass change measurement before and after dissolution of the coating on the plate.

  The anodized aluminum base material may be subjected to sealing treatment as necessary. These sealing treatments can be performed using known methods such as hot water treatment, boiling water treatment, water vapor treatment, sodium silicate treatment, dichromate aqueous solution treatment, nitrite treatment, and ammonium acetate treatment.

  Further, after these treatments, as a hydrophilization treatment, a water-soluble resin such as polyvinylphosphonic acid, a polymer or copolymer having a sulfonic acid group in the side chain, polyacrylic acid, a water-soluble metal salt ( For example, zinc borate) or a primer coated with a yellow dye, an amine salt or the like is also suitable.

  Further, a sol-gel treated substrate in which a functional group capable of causing an addition reaction by a radical as disclosed in JP-A No. 5-304358 is covalently used.

Application of Image Forming Layer In the present invention, the image forming layer is usually formed by dissolving the above components in a solvent and applying the solution on the hydrophilic layer. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like. However, it is not limited to this. These solvents are used alone or in combination. The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass. The coating, the coating amount of the hydrophilic layer obtained after drying (solid content) may be varied depending on the use, in the range of ^{0.1g / m 2 ~10g / m 2} , preferably 0.5 g / m ² ~ The range is 5 g / m ² . If the amount is too small, the printing durability is lowered. Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

Plate Making Method The planographic printing plate of the present invention can be exposed using a laser light source. Available laser light sources include semiconductor lasers, LEDs, helium neon lasers, YAG lasers, carbon dioxide lasers, and the like.

  The laser-exposed lithographic printing plate material is directly attached to a cylinder of a printing machine. The lithographic printing plate material is supplied with dampening water and printing ink via a roller of the printing press, and is developed by peeling off the image forming layer portion not irradiated with laser with dampening water / printing ink. .

  Hereinafter, the present invention will be specifically described with reference to examples, but the embodiments of the present invention are not limited thereto.

Preparation of planographic printing plate material 1 <Hydrophilic support>
A 0.24 mm aluminum plate was submerged in an aqueous solution containing 5 g / l sodium hydroxide at 50 ° C. and degreased by rinsing with deionized water. It is then electrochemically polished in an aqueous solution containing 4 g / l hydrochloric acid, 4 g / l boric acid and 5 g / l aluminum ions using alternating current at a temperature of 35 ° C. and a current density of 1200 A / m ^2. A surface topology with an average centerline roughness of 0.5 μm was formed. After rinsing with deionized water, the aluminum plate was then etched using an aqueous solution containing 300 g / l sulfuric acid at 60 ° C. for 180 seconds and rinsed with deionized water at 25 ° C. for 30 seconds. Subsequently, it was subjected to anodization in an aqueous solution containing 200 g / l sulfuric acid at a temperature of 45 ° C., a voltage of about 10 V and a current density of 150 A / m ² for about 300 seconds, and 3.00 g / m ² of Al ₂ O. ₃ anodized film, then rinsed with deionized water, post-treated with a solution containing 20 g / l sodium bicarbonate for 30 seconds at 40 ° C., followed by deionized water at 20 ° C. Rinse for 120 seconds and dry. The polished and anodized aluminum plate is then submerged in an aqueous solution containing 5% w / w citric acid for 60 seconds, adjusted to pH 7 using an aqueous solution of 2 mol / L sodium hydroxide for 60 seconds, and deionized. It was rinsed with water and dried at 25 ° C. to obtain a hydrophilic support for printing having a grain shape.

Application of Image Forming Layer The following composition was dispersed with a paint shaker for 1 hour to obtain an aqueous polymerization composition A.

<Polymerization composition A>
Polymerization initiator: 4-dichloro-6-hydroxy-s-triazine 5 parts by mass Water-soluble monomer (NK ester AM-90G; manufactured by Shin-Nakamura Chemical Co., Ltd.) 10 parts by mass Silicone surfactant (FZ-2161; Nippon Unicar Co., Ltd.) ) 0.1 part by mass Pure water 34.9 parts by mass

  An image forming layer coating solution having the following composition was prepared, applied on the hydrophilic support described above, and dried at 55 ° C. for 3 minutes. The applied image forming layer had a weight of 0.63 g.

<Image forming layer coating solution A>
Styrene-acrylonitrile copolymer emulsion (particle diameter 60 nm, melting point 102 ° C., solid content 20%) 6.88 parts by mass Polyacrylic acid resin (Glascore E15, solid content 15%; manufactured by Chiba Specialty Chemicals) 1.68 parts by mass Infrared ray Absorbing dye (ADS830WS; manufactured by Nippon Sebel Helgner) 1% aqueous solution 25 parts by mass Polymerizable composition A (solid content 30%) 2.08 parts by mass Pure water 14.38 parts by mass Polymerization composition A and heat melting The emulsion of styrene-acrylonitrile copolymer, which is a conductive particle, was cast on a film and dried, and then the dried product was analyzed using a differential thermal balance (TG-DTA) analyzer ThermoPlus 2 (manufactured by Rigaku Denki Kogyo). The measurement was performed at a temperature increase rate of 1 ° C./min. The polymerization initiation temperature T1 of the polysynthetic composition A was 158 ° C., and the melting point T2 of the styrene-acrylonitrile copolymer was 102 ° C.

  Next, an overcoat layer coating solution having the following composition was applied on the image forming layer using a wire bar # 5 and dried at 55 ° C. for 3 minutes. As a result, a lithographic printing plate material in which an image forming layer and an overcoat layer were laminated on a hydrophilic support was obtained.

<Overcoat layer coating solution>
Polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) 10 parts by mass Pure water 95 parts by mass Production of planographic printing plate material 2 Polymerizable composition A as the polymerizable composition and image forming layer coating liquid B as the image forming layer coating liquid Was used to produce a lithographic printing plate material 2 in the same manner as in the lithographic printing plate material 1.

<Image forming layer coating solution B>
Polymethyl methacrylate emulsion (particle diameter 60 nm, melting point 110 ° C., solid content 20%) 6.88 parts by mass Polyacrylic acid resin (Glascole E15, solid content 15%; manufactured by Chiba Specialty Chemicals) 1.68 parts by mass Infrared absorbing dye 1% aqueous solution of ADS830WS (manufactured by Nippon Sebel Helgner) 25 parts by weight Polymerizable composition A (solid content 30) 2.08 parts by weight Pure water 14.38 parts by weight The polymerization start temperature T1 of the polymerized composition A is The melting point of polymethyl methacrylate which is 158 ° C. and heat-meltable particles was 110 ° C.

Preparation of lithographic printing plate material 3 A lithographic printing plate material is produced in the same manner as the lithographic printing plate material 1 using the polymerizable composition B as the polymerizable composition and the image forming layer coating solution C as the image forming layer coating solution. 3 was obtained.

<Polymerization composition B>
Polymerization initiator (Compound 10) 5 parts by mass Water-soluble monomer (NK ester AM-90G; manufactured by Shin-Nakamura Chemical Co., Ltd.) 10 parts by mass Silicone surfactant (FZ-2161; Nippon Unicar Co., Ltd.) 0.1 part by mass Pure water 34.9 parts by mass <Image forming layer C>
Styrene-butyl acrylate-polymethyl methacrylate copolymer emulsion (particle diameter 60 nm, melting point 87 ° C., solid content 20%) 6.88 parts by mass Polyacrylic acid resin (Glascore E15, solid content 15%; manufactured by Chiba Specialty Chemicals) 1.68 parts by mass Infrared absorbing pigment (ADS830WS; manufactured by Nippon Sebel Helgner) 1% aqueous solution 25 parts by mass Polymerizable composition B (solid content 30%) 2.08 parts by mass Pure water 14.38 parts by mass Polymerization The polymerization initiation temperature T1 of the composition B was 96 ° C., and the melting point of polymethyl methacrylate, which is a heat-meltable particle, was 87 ° C.

Preparation of lithographic printing plate material 4 A lithographic printing plate material is produced in the same manner as the lithographic printing plate material 1 using the polymerizable composition B as the polymerizable composition and the image forming layer coating solution D as the image forming layer coating solution. 4 was obtained.

<Image forming layer coating solution D>
Styrene-acrylonitrile copolymer emulsion (particle diameter 60 nm, melting point 102 ° C., solid content 20%) 6.88 parts by mass Polyacrylic acid resin (Glascore E15, solid content 15%; manufactured by Chiba Specialty Chemicals) 1.68 parts by mass Infrared ray Absorbing dye (ADS830WS; manufactured by Nippon Sebel Helgner) 1% aqueous solution 25 parts by weight Polymerizable composition B (solid content 30%) 2.08 parts by weight Pure water 14.38 parts by weight Initiation of polymerization of polymerization composition B The temperature T1 was 96 ° C., and the melting point of the styrene-acrylonitrile copolymer which is a heat-meltable particle was 102 ° C.

Preparation of lithographic printing plate material 5 A lithographic printing plate material is produced in the same manner as the lithographic printing plate material 1 using the polymerizable composition B as the polymerizable composition and the image forming layer coating solution D as the image forming layer coating solution. 5 was obtained.

<Image forming layer coating solution D>
Styrene-butyl acrylate-polymethyl methacrylate copolymer emulsion (particle size 60 nm, melting point 87 ° C., solid content 20%) 6.88 parts by mass Polyacrylic acid resin (Glascore E15, solid content 15%; manufactured by Chiba Specialty Chemicals) 1.68 parts by mass Infrared absorbing dye (ADS830WS; manufactured by Nippon Sebel Helgner) 1% aqueous solution 25 parts by mass Polymerizable composition A (solid content 30%) 2.08 parts by mass Pure water 14.38 parts by mass Polymerization The polymerization initiation temperature T1 of the composition A was 158 ° C., and the melting point of the styrene-butyl acrylate-polymethyl methacrylate copolymer as the heat-meltable particles was 87 ° C.

Preparation of lithographic printing plate material 6 A lithographic printing plate material 6 was obtained by the same method except that the image forming layer coating liquid D was used as the image forming layer coating liquid.

<Image forming layer D>
Polymethyl methacrylate emulsion (particle size 60 nm, melting point 110 ° C., solid content 20%) 9.83 parts by mass Polyacrylic acid resin (Glascole E15, solid content 15%; manufactured by Chiba Specialty Chemicals) 0.83 parts by mass Infrared absorbing dye 1% aqueous solution of ADS830WS (manufactured by Nippon Sebel Helgner) 25 parts by weight Polymerizable composition A (solid content 30%) 0.83 parts by weight Pure water 13.96 parts by weight Polymerization start temperature T1 for polymerization composition A Was 158 ° C., and the melting point of polymethyl methacrylate, which is a heat-meltable particle, was 110 ° C.

Preparation of lithographic printing plate material 7 A lithographic printing plate material 7 was obtained by the same method except that the image forming layer coating liquid E was used as the image forming layer coating liquid.

<Image forming layer E>
Styrene-butyl acrylate-polymethyl methacrylate copolymer emulsion (particle diameter 60 nm, melting point 90 ° C., solid content 20%) 9.83 parts by mass Polyacrylic acid resin (Glascore E15, solid content 15%; manufactured by Chiba Specialty Chemicals) 0.83 parts by mass A 1% aqueous solution of infrared absorbing dye (ADS830WS; manufactured by Nippon Sebel Helgner) 25 parts by mass Polymerizable composition A (solid content 30%) 0.83 parts by mass Pure water 13.96 parts by mass Polymerization The polymerization initiation temperature T1 of the composition A was 158 ° C., and the melting point of the styrene-butyl acrylate-polymethyl methacrylate copolymer as the heat-meltable particles was 87 ° C.

<Preparation and printing of planographic printing plates>
The obtained lithographic printing plate materials 1 to 5 were subjected to a plate setter equipped with a semiconductor laser, with an emission wavelength of 830 nm laser beam {beam diameter 10 μm (1 / e ² ), output 300 mW}, and the plate surface energy intensity of 400 mJ / cm. to 25 mJ / cm ² every ² to 100 mJ / cm ^2, were exposed images containing 1% halftone dot image.

  When the temperature of the laser irradiation part on the surface of the planographic printing plate material was measured with a non-contact infrared thermometer, it was confirmed to be 220 ° C.

  For evaluation of scratch resistance, a portion of the lithographic printing plate having no image (a portion not irradiated with a laser beam) was scratched with a nail.

  The lithographic printing plate material is attached to the cylinder of the Lithrone 20 Kikushiki offset printing machine without developing, and is used as a 2% aqueous solution of Astro Mark 3 (manufactured by Nikken Chemical Research Co., Ltd.) in dampening water as a printing ink. Printing was performed using High Unity Red (manufactured by Toyo Ink Manufacturing Co., Ltd.).

<Evaluation>
The amount of energy reproduced by the 1% halftone image on the obtained printed material was defined as the sensitivity of the lithographic printing plate. In addition, the number of printed sheets until the 1% image reproduced with the amount of energy deteriorated was defined as the number of printed sheets.

  As evaluation of scratch resistance, the case where the scratched part of the nail did not become dirty was confirmed as ◯, and the case where it became dirty was evaluated as X.

  It can be seen that good sensitivity and printing durability can be obtained by setting the melting point T1 of the heat-fusible particles and the polymerization start temperature T2 of the polysynthetic composition within the range of the present invention. Moreover, it turns out that scratch resistance is favorable in content of a heat-meltable particle | grain being 60% or less.

Claims (6)

A lithographic printing plate material having an image forming layer containing at least one compound selected from a heat-meltable particle, a polymerizable monomer having an unsaturated ethylene group and a polymerizable prepolymer on a hydrophilic support, and a polymerization initiator The polymerization start temperature T1 by at least one compound selected from the polymerizable monomer having an unsaturated ethylene group and the polymerizable prepolymer and a polymerization initiator is higher than the melting point T2 of the hot-melt particles. Lithographic printing plate material to do. The difference between the polymerization start temperature T1 by the at least one compound selected from the monomer having an unsaturated ethylene group and the polymerizable prepolymer and the polymerization initiator and the melting point T2 of the hot-melt particles is 10 to 50 ° C. or less. The lithographic printing plate material according to claim 1, wherein the lithographic printing plate material is a lithographic printing plate material. The lithographic printing plate material according to claim 1 or 2, wherein at least one compound selected from a polymerizable monomer having an unsaturated ethylene group and a polymerizable prepolymer is water-soluble. The lithographic printing plate material according to any one of claims 1 to 3, wherein the content of the heat-fusible particles in the image forming layer is 60% by mass or less. The lithographic printing plate material according to any one of claims 1 to 4, wherein the polymerization start temperature T1 is higher than at least one compound selected from a monomer having an unsaturated ethylene group and a polymerizable prepolymer and a polymerization initiator. A method for preparing a lithographic printing plate, characterized by drawing at a temperature. A planographic printing plate material on which an image is drawn by the method of preparing a planographic printing plate according to claim 5 is attached to a cylinder of a printing machine, and then developed while supplying dampening water and printing ink. Processing method for printing plates.