JP2006248143A - Printing plate material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing plate material capable of being developed on a machine and having excellent plate wear and high sensitivity. <P>SOLUTION: In the printing plate material having a thermosensitive image forming layer on the substrate having a hydrophilic surface, the thermosensitive image forming layer includes (A) a water-insoluble blocked isocyanate compound and (B) a water-soluble crosslinking compound, (B) the water-soluble crosslinking compound is a compound having (b1) a guanidine compound or (b2) a compound having a hydroxy group, and further having an epoxy group, a carbonyl group, or an acetoacetyl group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing plate material, and more particularly to a printing plate material capable of image formation by a computer-to-plate (CTP) method.

  At present, in the field of printing, printing by the CTP method has been performed with the digitization of print image data. However, this printing is inexpensive and easy to handle and is equivalent to a conventional so-called PS plate. Therefore, there is a demand for a printing plate material for a CTP system having the following printability.

  In particular, it has a direct imaging (hereinafter referred to as DI) performance that does not require development processing with a special agent in recent years, and can be applied to a printing machine having this function, and has the same usability as the PS plate. There is a need for a general-purpose processless plate.

  An infrared laser recording system having a wavelength of near infrared to infrared is mainly used for image formation of a thermal processless plate. Thermal processless plates capable of image formation by this method are roughly classified into an ablation type and a heat fusion image layer on-machine development type.

  Examples of the ablation type include those described in JP-A-8-507727, JP-A-6-186750, JP-A-6-199064, JP-A-7-314934, JP-A-10-58636, and JP-A-10-244773. Can be mentioned.

  In these, for example, a hydrophilic layer and a lipophilic layer are laminated on a base material with either layer as a surface layer. If the surface layer is a hydrophilic layer, it is possible to form an image portion by exposing it like an image, ablating the hydrophilic layer and removing it like an image to expose the lipophilic layer. However, since contamination inside the exposure apparatus due to the ablated surface layer scattered matter becomes a problem, the exposure apparatus may require a special suction device, and the versatility of the exposure apparatus is low.

  On the other hand, development of a printing plate material that can form an image without causing ablation and does not require a development process or a wiping process using a special developer is also underway. For example, as disclosed in Japanese Patent No. 2938397 and Japanese Patent No. 2938397, dampening water or ink is used on a printing press using a thermoplastic fine particle and a binder of a water-soluble polymer compound in a thermal image forming layer. And a CTP printing plate material that can be developed.

  However, such thermoplastic fine particles may show a slight heat-fusibility even in a relatively low temperature range of about 50 to 60 ° C., and thermoplastic fine particles are used as the main material of the image forming material. In some cases, the on-press developability may deteriorate when stored at a temperature of 50 to 60 ° C., and the storage stability is not satisfactory.

  On the other hand, a blocked isocyanate compound is known as a material capable of forming an image by heat. Blocked isocyanate is a compound obtained by chemically blocking an isocyanate group of an isocyanate compound with a specific material, and does not show reactivity at a specific temperature (generally around 100 ° C.) or lower.

  This block dissociates at a specific temperature or higher, and the isocyanate group is regenerated and becomes reactive. Since there is a clear threshold value for the dissociation temperature of the block that exhibits reactivity, a relatively good storage stability is exhibited in a temperature range below this dissociation temperature.

  As an application example to a printing plate material, for example, a blocked isocyanate compound is contained in the image forming layer, and a material having a functional group that reacts with an isocyanate group is contained in the image forming layer or a layer adjacent to the image forming layer. Then, only the heated image-forming layer is reacted (cross-linked with isocyanate), and this reaction is used to produce a difference between ink inking property and dampening water acceptability to form a printing plate. An example is given.

  As a specific example, for example, a recording layer containing a blocked isocyanate and a polymer having active hydrogen capable of reacting with isocyanate is provided on the surface of a substrate having a hydrophilic surface, and at least any of the substrate and the recording layer is provided. On the other hand, a lithographic printing original plate characterized by containing a photothermal conversion substance has been proposed (see, for example, Patent Document 1).

  As another example, a functional group in a three-dimensionally cross-linked hydrophilic binder polymer reacts with a specific blocked isocyanate dispersed in the hydrophilic binder resin in a size of 0.3 μm or less, thereby causing a heated printing portion. An image forming method for hydrophobizing the surface has been proposed (see, for example, Patent Document 2).

  In this example, there is an advantage that development including on-press development is completely unnecessary, but since the hydrophilic layer contains a hydrophobic material called blocked isocyanate, the hydrophilicity is lowered even in the non-heated part, There is a problem in that soiling is likely to occur, the hydrophilic layer is easily hydrophobized by pressure, and even a slight scratch mark is likely to become dirty.

  As an example applied to on-press development CTP, it has a heat-sensitive layer containing hydrophobic polymer particles, a blocked isocyanate compound, a hydrophilic resin having a group capable of reacting with isocyanate, and a photothermal conversion substance on a hydrophilic support. Examples thereof include a printing plate material (see Patent Document 3) and a printing plate material having a thermosensitive layer containing polymer particles having a blocked isocyanate group, a hydrophilic resin, and a photothermal conversion substance on a hydrophilic support (Patent Document 4). reference).

However, although these printing plate materials can be adapted to digital image exposure using laser light or the like, the printing durability may be insufficient and the sensitivity becomes insufficient when trying to increase the printing durability. It was difficult to achieve both sensitivity and printing durability.
JP 62-164049 A JP 2001-310566 A JP 2002-225451 A JP 2002-283758 A

  An object of the present invention is to provide a printing plate material capable of on-press development, having excellent printing durability and high sensitivity.

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

(Claim 1)
In a printing plate material having a thermosensitive image forming layer on a substrate having a hydrophilic surface, the thermosensitive image forming layer contains (A) a water-insoluble blocked isocyanate compound and (B) a water-soluble crosslinkable compound, (B) The printing plate, wherein the water-soluble crosslinkable compound is (b1) a guanidine compound or (b2) a compound having a hydroxyl group and having an epoxy group, a carboxyl group, a carbonyl group or an acetoacetyl group material.

(Claim 2)
The printing plate material according to claim 1, wherein the water-soluble crosslinkable compound (B) has a molecular weight of 120 to 30,000.

(Claim 3)
The printing plate material according to claim 1, wherein the heat-sensitive image forming layer is a layer that can be developed on a printing press.

(Claim 4)
The printing plate material according to any one of claims 1 to 3, wherein the heat-sensitive image forming layer contains (A) 30% by mass to 90% by mass of the water-insoluble blocked isocyanate compound.

(Claim 5)
The printing plate material according to any one of claims 1 to 4, wherein the (A) water-insoluble blocked isocyanate compound is a compound obtained by adding a blocking agent and a low molecular weight polyol to tolylene diisocyanate. .

  Moreover, the more preferable aspect of the structure of this invention is the following.

(6)
The water-soluble crosslinking compound is guanidine carbonate, guanidine nitrate, guanidine phosphate, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, dimethylolbutanoic acid, glyoxal modified starch or acetoacetylated polyvinyl alcohol. The printing plate material according to any one of claims 1 to 5, wherein:

  According to the configuration of the present invention, it is possible to provide a printing plate material that can be developed on-press, has excellent printing durability, and high sensitivity.

  The present invention is described in detail below.

  The present invention relates to a printing plate material having a heat-sensitive image forming layer on a substrate having a hydrophilic surface, wherein the heat-sensitive image forming layer comprises (A) a water-insoluble blocked isocyanate compound and (B) a water-soluble crosslinkable compound. And (B) the water-soluble crosslinkable compound has a molecular weight of (b1) a guanidine compound or (b2) a compound having a hydroxyl group and having an epoxy group, a carboxyl group, a carbonyl group or an acetoacetyl group. To do.

  In particular, the present invention enables on-press development by containing (b1) a guanidine compound or (b2) a compound having a hydroxyl group and having an epoxy group, a carboxyl group, a carbonyl group or an acetoacetyl group in the heat-sensitive image forming layer. It is possible to provide a printing plate material that has excellent printing durability and high sensitivity.

(Water-insoluble blocked isocyanate compound)
The blocked isocyanate compound according to the present invention is a reaction compound of an isocyanate compound and an isocyanate group blocking agent, and has a solubility in water (g number dissolved in 100 g of water at 25 ° C.) of 0.1 or less. .

  As the blocked isocyanate compound, a compound obtained by further reacting a polyol with a reaction compound of an isocyanate compound and a blocking agent is preferable.

(Isocyanate compound)
The isocyanate compound is a compound having an isocyanate group. Examples of the isocyanate compound include aromatic polyisocyanates [diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), polyphenylpolymethylene polyisocyanate (crude MDI), naphthalene diisocyanate (NDI). Etc.]; Aliphatic polyisocyanates [1,6-hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), etc.]; Alicyclic polyisocyanates [isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (hydrogenated MDI) Cyclohexylene diisocyanate, etc.]; aromatic polyisocyanate [xylylene diisocyanate (XDI), tetramethylxylene dii Cyanate (TMXDI), etc.]; these modified products (burette group, isocyanurate group, carbodiimide group, oxazolidine group-containing modified product, etc.); and these polyisocyanates and active hydrogen-containing compounds having a molecular weight of 50 to 5,000. A urethane prepolymer having a terminal isocyanate group may be mentioned.

  Further, polyisocyanate compounds described in JP-A-10-72520 can also be preferably used.

  Of the above, tolylene diisocyanate is particularly preferred because of its fast reactivity.

(Blocking agent)
The blocking agent is a compound having a group that undergoes an addition reaction with an isocyanate group to generate a urethane bond or a urea bond. For example, an alcohol-based blocking agent such as methanol or ethanol, a phenol-based blocking agent such as phenol or cresol, formaldoxime, Oxime blocking agents such as acetaldoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, cyclohexanone oxime, acetoxime, diacetyl monooxime, benzophenone oxime, acid amide blocking agents such as acetanilide, ε-caprolactam, γ-butyrolactam, dimethyl malonate , Active methylene block agents such as methyl acetoacetate, mercaptan block agents such as butyl mercaptan, imide blocks such as succinic acid imide and maleic acid imide Agents, imidazole blocking agents such as imidazole and 2-methylimidazole, urea blocking agents such as urea and thiourea, carbamate blocking agents such as phenyl N-phenylcarbamate, amine blocking agents such as diphenylamine and aniline, Examples thereof include imine blocking agents such as ethyleneimine and polyethyleneimine. Among these, it is particularly preferable to use an oxime blocking agent.

  As the addition amount of the blocking agent, the active hydrogen group in the blocking agent and the active hydrogen group of the polyol described below are combined and contained in an amount of 1.0 to 1.1 equivalents relative to the isocyanate group of the isocyanate compound. It is preferable to make it.

  If it is less than 1.0, unreacted isocyanate groups remain, and if it exceeds 1.1, the blocking agent or the like becomes excessive, which is not preferable.

  The dissociation temperature of the blocking agent is preferably 80 to 200 ° C, more preferably 80 to 160 ° C, and more preferably 80 to 130 ° C.

(Polyol)
As the blocked isocyanate compound according to the present invention, those obtained by further adding a polyol to the adduct of the above blocking agent are preferably used.

  By adding a polyol, the storage stability of the blocked isocyanate compound can be improved. Further, the image strength when the image is formed by heating is improved, and the printing durability is improved.

  Polyols include propylene glycol, triethylene glycol, glycerin, trimethylol methane, trimethylol propane, pentaerythritol, neopentyl glycol, 1,6-hexylene glycol, butanediol, hexamethylene glycol, xylylene glycol, sorbitol, and sucrose. Polyhydric alcohols such as these, polyether polyols obtained by addition polymerization of ethylene oxide or propylene oxide with these polyhydric alcohols or polyamines, or both, polytetramethylene ether polyols, polycarbonate polyols, polycaprolactone polyols In addition, the polyhydric alcohols such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, fumaric acid, maleic acid Polymer polyols obtained by grafting vinyl monomers onto polyester polyols, polybutadiene polyols, acrylic polyols, castor oil, polyether polyols or polyester polyols obtained by reacting with polybasic acids such as acid and azelaic acid And epoxy-modified polyols.

  Among these, propylene glycol, triethylene glycol, glycerin, trimethylol methane, trimethylol propane, pentaerythritol, neopentyl glycol, 1,6-hexylene glycol, butanediol, hexamethylene glycol, xylylene glycol, sorbitol, etc. A polyol having a molecular weight of 50 to 5000 can be preferably used, and a low molecular weight polyol having a molecular weight of 50 to 500 can be particularly preferably used.

  As the addition amount of the polyol, the amount of active hydrogen combined with the polyol and the blocking agent as described above is preferably 1.0 to 1.1 equivalents relative to the isocyanate group of the isocyanate compound. Is preferably in the range of 0.1 to 0.9 equivalents relative to the isocyanate group of the isocyanate compound, and particularly in this range, the storage stability of the blocked isocyanate compound is improved.

(Blocking method)
As a method for blocking the isocyanate compound, for example, the isocyanate compound is heated to about 40 to 120 ° C. under an inert gas atmosphere under anhydrous conditions, and a predetermined amount of the blocking agent is dropped and mixed while stirring. The method of making it react over several hours, continuing stirring is mentioned.

  At this time, any solvent can be used. Moreover, a well-known catalyst, for example, an organometallic compound, a tertiary amine, a metal salt etc. can also be used.

  Examples of the organometallic catalyst include stannous catalysts such as stannous octoate, dibutyltin diacetate, and dibutyltin dilaurate; lead-based catalysts such as lead 2-ethylhexanoate; and tertiary amines such as triethylamine, N, N-dimethylcyclohexylamine, triethylenediamine, N, N′-dimethylpiperazine, diazabicyclo (2,2,2) -octane, etc. are examples of metal salt catalysts such as cobalt naphthenate, calcium naphthenate, and naphthenic acid. Lead lithium oxide etc. are mentioned. The usage-amount of these catalysts is 0.001-2 mass parts normally with respect to 100 mass parts of polyisocyanate compositions, Preferably it is 0.01-1 mass part.

  Since the blocked isocyanate compound of the present invention is also a compound with a polyol, the blocking agent and the polyol are reacted with the isocyanate compound. After the isocyanate compound and the polyol are reacted first, the remaining isocyanate group and the blocking agent are reacted. In addition, after the isocyanate compound and the blocking agent are reacted first, the remaining isocyanate group and the polyol may be reacted.

  As a preferable average molecular weight of the blocked isocyanate compound of the present invention, a weight average molecular weight is preferably 500 to 2,000, and more preferably 600 to 1,000. Within this range, the balance between reactivity and storage stability becomes good.

  The content of the (A) water-insoluble blocked isocyanate compound according to the present invention in the heat-sensitive image forming layer is preferably in the range of 20% by mass to 90% by mass, particularly preferably in the range of 30% by mass to 90% by mass.

((B) Water-soluble crosslinkable compound)
The water-soluble crosslinkable compound according to the present invention is (b1) a guanidine compound or (b2) a compound having a hydroxyl group and having an epoxy group, a carboxyl group, a carbonyl group or an acetoacetyl group.

  The water solubility of the water-soluble crosslinkable compound means that 10 g or more is dissolved in 100 g of water at 25 ° C., and the crosslinkable compound means that which can react with the isocyanate compound according to the present invention.

  As the water-soluble crosslinkable compound according to the present invention, a compound having a molecular weight of 120 to 30,000 is preferable from the viewpoint of on-press development property and printing durability.

  The guanidine compound according to the present invention is a derivative of guanidine, and examples thereof include guanidine carbonate, guanidine phosphate, guanidine sulfamate, and guanidine nitrate.

  Of these, guanidine carbonate, guanidine phosphate, and guanidine nitrate are particularly preferably used.

  Examples of the compound having a hydroxyl group and having an epoxy group include a compound obtained by adding an epoxy group to a polyol compound, and a polyol compound having a plurality of epoxy groups such as glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, and sorbitol polyglycidyl ether. Is preferably used.

  Examples of the compound having a hydroxyl group and a carboxyl group include dimethylolbutanoic acid and dimethylolpropionic acid. Of these, dimethylol butanoic acid is particularly preferably used.

  Examples of the compound having a hydroxyl group and a carbonyl group include compounds obtained by modifying a polyol compound with glyoxal.

  Of these, glyoxal-modified starch is particularly preferably used.

  Examples of the compound having a hydroxyl group and having an acetoacetyl group include a compound obtained by adding an acetoacetyl group to a polyol compound. For example, by a method as described in JP-A-8-259672, one of the hydroxyl groups of a polyol compound is exemplified. It is a compound obtained by acetoacetylating a part.

  Of these, acetoacetylated polyvinyl alcohol and acetoacetylated cellulose are particularly preferably used.

  The water-soluble crosslinkable compound (B) according to the present invention preferably has a molecular weight of 120 to 30000. When the water-soluble crosslinkable compound is a polymer, the molecular weight refers to its weight average molecular weight.

  The water-soluble crosslinkable compound according to the present invention crosslinks with the isocyanate compound of the present invention at high density in the exposed area, and also crosslinks or bonds with a hydrophilic group such as a hydroxyl group on the surface of the hydrophilic layer, thereby exposing the exposed area. Since it has the effect of improving the strength of the image forming layer and the effect of improving the adhesion of the image forming layer to the hydrophilic layer, and has a function of promoting on-machine development in the non-image area, It is estimated that developability can be imparted.

  The content of the (B) water-soluble crosslinkable compound according to the present invention is preferably 10% by mass to 90% by mass, particularly 30% by mass to 60% by mass with respect to (A) the water-insoluble blocked isocyanate compound. preferable.

(Manufacture of water dispersion)
The heat-sensitive image forming layer according to the present invention is preferably formed by coating using an aqueous coating solution containing a dispersion of a blocked isocyanate compound as described above.

  The blocked isocyanate compound obtained as described above can be made into a dispersion by, for example, adding a surfactant and water and mixing and stirring strongly using a homogenizer or the like. An aqueous coating solution for the image forming layer can be prepared.

  Examples of surfactants include anionic surfactants such as sodium dodecylbenzene sulfonate, sodium lauryl sulfate, sodium dodecyl diphenyl ether disulfonate, sodium succinate dialkyl ester sulfonate, polyoxyethylene alkyl ester, polyoxyethylene alkyl aryl, and the like. Nonionic surfactants such as ether, or alkylbetaine type salts such as lauryl betaine and stearyl betaine salts, both amino acid types such as lauryl-β-alanine, lauryl di (aminoethyl) glycine, and octyldi (aminoethyl) glycine Surfactant etc. can be mentioned. These can be used alone or in combination of two or more. Of these, nonionic surfactants are preferred.

  The solid content of the aqueous dispersion of the blocked isocyanate compound is preferably 10 to 80% by mass. As addition amount of surfactant, it is preferable that it is 0.01-20 mass% in solid content of an aqueous dispersion.

  When an organic solvent is used for the blocking reaction of the isocyanate compound, the organic solvent can be removed after forming an aqueous dispersion.

(Water-soluble compounds)
The heat-sensitive image forming layer according to the present invention can contain a water-soluble compound. As the water-soluble compound, any compound can be used as long as it is a compound that can dissolve 0.5 g or more in 100 g of water at 20 ° C.

  A compound that can be dissolved in 2 g or more in 100 g of water at 20 ° C. is preferable for obtaining good on-press developability, and a solid at 20 ° C. is preferable for maintaining the strength of the heat-sensitive image forming layer. Specific examples include the following compounds.

  Oligosaccharides: trehalose, sucrose, maltose, cyclodextrin, etc.

  Water-soluble polymer compounds: polysaccharides (starch, cellulose, polyuronic acid, pullulan, chitosan, or derivatives thereof), polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, polyacrylic acid, Polyacrylate, polyacrylamide, polyvinylpyrrolidone, etc.

(Hydrophilic fine particles)
The heat-sensitive image forming layer according to the present invention can contain hydrophilic fine particles. As the hydrophilic fine particles, those having a hydrophilic surface and a particle size of 2 μm or less can be preferably used in terms of the on-press development acceleration effect.

  Specific examples include the following.

  Hydrophilic resin particles: chitosan particles, alginate particles and the like.

  Hydrophilic material-coated resin particles: Particles obtained by using resin particles as a core and coating them with a hydrophilic material (metal oxide or the like).

  Metal oxide particles: particles of silica, alumina, aluminosilicate, titania, zirconia, etc. It may be porous.

  Metal oxide colloid: Colloidal silica, alumina sol or the like having a particle size of about 3 to 200 nm. Within this range, the on-press developability is better when the particle size is larger. The shape may be any shape such as a spherical shape, a chain shape, a necklace shape, or a feather shape.

  Layered mineral particles: clay minerals such as kaolinite, halloysite, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), vermiculite, mica (mica), chlorite, and hydrotalcite, layered polysilicate (kanemite, macatite) , Eyelite, magadiite, kenyaite, etc.). Among them, it is considered that the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of the layered mineral having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge) and the like. In particular, synthetic fluorine mica is preferable because it can be obtained with a stable quality such as particle diameter. Among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.

  Also used are intercalation compounds of the above-mentioned layered minerals (pillar crystals, etc.), those subjected to ion exchange treatment, and those subjected to surface treatment (silane coupling treatment, compounding treatment with organic binder, etc.) can do.

  As for the size of the layered mineral particles, the average particle diameter (maximum length of the particles) is 2 μm or less in the state of being contained in the layer (including the case of undergoing the swelling process and dispersion peeling process), and the average aspect The ratio (maximum particle length / particle thickness) is preferably 20 or more, more preferably an average particle diameter of 1 μm or less, and an average aspect ratio of 50 or more.

  Among the above, metal oxide colloid is preferable from the viewpoint of improving the strength of the image area formed by heating, and layered clay mineral particles are preferable from the viewpoint that good on-press developability can be obtained with a small amount of addition. .

(Other materials that can be included in the thermal image forming layer)
The heat-sensitive image forming layer according to the present invention can contain a material having a catalytic function that promotes dissociation of the blocking agent of the blocked isocyanate compound and promotes the reaction between the regenerated isocyanate group and another functional group.

  As a material having a catalytic function, for example, an organometallic compound, a tertiary amine, a metal salt, or the like can be used.

  In addition, the thermosensitive image forming layer according to the present invention may further contain microcapsules enclosing hydrophobic thermoplastic particles or a hydrophobic material.

(Base material)
The base material having a hydrophilic surface according to the present invention is a base material having a surface where the thermal image-forming layer is removed at the time of printing and has a surface that can become a water-receptive and non-image part. The base material which processed and provided the hydrophilic layer containing the hydrophilic surface layer which has a hydrophilic surface layer can be used.

  As the base material according to the present invention, a known material used as a substrate for a printing plate can be used as long as the surface shape is within the range specified in the present invention. For example, a metal plate, a plastic film, a polyolefin, etc. And a composite substrate obtained by appropriately laminating the above materials.

  The thickness of the base material 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.

  As a base material which concerns on this invention, the metal plate which hydrophilized the base-material surface is used preferably.

  Examples of the metal plate include iron, stainless steel, and aluminum. In the present invention, aluminum or an aluminum alloy (hereinafter referred to as an aluminum plate) is particularly preferable because of the relationship between specific gravity and rigidity. Those subjected to any of the known roughening treatment, anodic oxidation treatment, and surface hydrophilization treatment (so-called aluminum grained plate) are more preferred.

  The aluminum grained plate may be manufactured by any method as long as the surface shape is in the surface characteristics (Ra, A2) specified by the present invention, but the surface shape specified by the present invention can be obtained. As one of the methods, a method disclosed in JP-A-10-869 can be exemplified. According to the manufacturing method shown here, the value of A2 can be made into the range of 1-10 by selecting suitable electrolytic-roughening conditions.

  Various aluminum alloys can be used as the base material according to the present invention, for example, metals such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium, iron, and aluminum. These alloys are used.

  The aluminum plate used as the 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 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 and desmutted. It is preferable to perform the 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 surface roughening by the brush polishing method is, for example, rotating a rotating brush using brush bristles having a diameter of 0.2 to 0.8 mm, and for example, volcanic ash particles having a particle diameter of 10 to 100 μm on water. While supplying the uniformly dispersed slurry, the brush can be pressed. The roughening by honing polishing is performed by, for example, uniformly dispersing volcanic ash particles having a particle diameter of 10 to 100 μm in water, injecting pressure from a nozzle and injecting them obliquely to the surface of the base material. Can do. Also, for example, abrasive particles having a particle size of 10 to 100 μm are coated on the surface of the substrate so as to exist 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 sheets and applying a pressure to transfer the rough surface pattern of the sheet.

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 base material, 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 neutralize 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 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 anodized coating amount is obtained by, for example, 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 film, It is obtained from mass change measurement before and after dissolution of the coating on the plate.

  The anodized base material may be subjected to a 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.

  Examples of the plastic film used as the substrate include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, cellulose esters, and the like.

  In the present invention, among these plastic films, polyester films such as polyethylene terephthalate (hereinafter sometimes abbreviated as PET) and polyethylene naphthalate (hereinafter sometimes abbreviated as PEN) are preferably used as the base material. The

  Furthermore, it is preferable to use a support obtained by the method described in JP-A No. 10-10676 and having a thermal dimensional change rate of from 0.001% to 0.04% at 120 ° C. for 30 seconds.

  A preferable polyester film is an unstretched polyester film, a uniaxially stretched polyester film, or a biaxially stretched polyester film.

  Of these, a longitudinally stretched polyester film uniaxially stretched in the film extrusion direction (longitudinal direction) is particularly preferred.

(Applying undercoat layer to substrate)
In the polyester film base material, easy adhesion treatment or undercoat layer coating can be performed in order to have various functions.

  Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment.

  As the undercoat layer, a layer containing gelatin or latex is preferably provided on the polyester film support. Among them, the antistatic undercoat layer described in paragraph Nos. 0044 to 0116 of JP-A-7-191433 is preferably used. Further, a conductive layer such as a conductive polymer-containing layer described in paragraph Nos. 0031 to 0073 of JP-A-7-20596 or a metal oxide-containing layer described in paragraph Nos. 0074 to 0081 of JP-A-7-20596 is provided. It is preferable. The conductive layer may be coated on either side as long as it is on the polyester film support, but it is preferably coated on the opposite side of the image forming functional layer with respect to the support. When this conductive layer is provided, the chargeability is improved, the adhesion of dust and the like is reduced, and white spots failure during printing is greatly reduced.

(Hydrophilic layer)
In the present invention, when the above plastic film is used as a substrate, a hydrophilic layer is provided on the substrate to form a substrate having a hydrophilic surface.

  In this case, the hydrophilic layer preferably has a porous structure.

  In order to form a hydrophilic layer having a porous structure, the following materials for forming a hydrophilic matrix are preferably used.

  As a material for forming the hydrophilic matrix, a metal oxide is preferable.

(Metal oxide)
The metal oxide preferably contains fine metal oxide particles, and examples thereof include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The form of the metal oxide fine particles may be spherical, needle-like, feather-like or any other form. The average particle diameter is preferably in the range of 3 to 100 nm, and several kinds of metal oxides having different average particle diameters are used. Fine particles can be used in combination. The surface of the particles may be surface treated.

  The metal oxide fine particles can be used as a binder by utilizing the film forming property. The decrease in hydrophilicity is less than when an organic binder is used, and it is suitable for use in a hydrophilic layer.

(Colloidal silica)
Among these, colloidal silica can be particularly preferably used. Colloidal silica has the advantage of high film-forming properties even under relatively low temperature drying conditions, and can provide good strength. The colloidal silica preferably includes necklace-like colloidal silica, which will be described later, and fine particle colloidal silica having an average particle size of 20 nm or less, and the colloidal silica preferably exhibits alkalinity as a colloidal solution.

  Necklace-shaped colloidal silica is a general term for an aqueous dispersion of spherical silica whose primary particle diameter is of the order of nm, and spherical colloidal silica having a primary particle diameter of 10 to 50 nm bonded to a length of 50 to 400 nm. It means colloidal silica in the form of “pearl necklace”.

  The pearl necklace shape (that is, a pearl necklace shape) means that the image of the state in which the silica particles of colloidal silica are connected and linked has a shape like a pearl necklace.

  In the present invention, porous metal oxide particles having a particle size of less than 1 μm can be contained as a porous material having a hydrophilic layer matrix structure.

(Porous metal oxide particles)
As the porous metal oxide particles, the following porous silica, porous aluminosilicate particles, or zeolite particles can be preferably used.

(Porous silica, porous silica, porous aluminosilicate particles)
The porous silica particles are generally produced by a wet method or a dry method. In the wet method, the gel obtained by neutralizing the aqueous silicate solution can be obtained by drying and pulverizing, or by pulverizing the precipitate deposited by neutralization. In the dry method, silicon tetrachloride is burned together with hydrogen and oxygen to obtain silica. These particles can be controlled in their porosity and particle size by adjusting the production conditions. As the porous silica particles, those obtained from a wet gel are particularly preferable.

  The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764. That is, amorphous composite particles synthesized by hydrolysis using aluminum alkoxide and silicon alkoxide as main components. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. In addition, those produced as composite particles of three or more components by adding an alkoxide of another metal during production can also be used in the present invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.

  The porosity of the particles is preferably 0.5 ml / g or more in terms of pore volume, more preferably 0.8 ml / g or more, and further preferably 1.0 to 2.5 ml / g. preferable. The pore volume is closely related to the water retention of the coating film. The larger the pore volume, the better the water retention, the less likely to get dirty during printing, and the greater the water volume latitude, but more than 2.5 ml / g When it becomes large, the particles themselves become very brittle, so that the durability of the coating film is lowered. Conversely, if the pore volume is less than 0.5 ml / g, the printing performance may be slightly insufficient.

(Measurement method of pore volume)
Here, the pore volume is measured by using Autosorb-1 (manufactured by Cantachrome) and assuming that the voids of the powder are filled with nitrogen by nitrogen adsorption measurement using a constant volume method. Thus, the relative pressure is calculated from the nitrogen adsorption amount at 0.998.

(Zeolite particles)
Zeolite is a crystalline aluminosilicate, and is a porous body having regular three-dimensional network voids having a pore diameter of 0.3 nm to 1 nm.

  Further, the hydrophilic layer matrix structure constituting the hydrophilic layer can contain layered clay mineral particles. Examples of the layered mineral particles include kaolinite, halloysite, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), clay minerals such as vermiculite, mica (mica), chlorite, hydrotalcite, layered polysilicic acid. Examples thereof include salts (kanemite, macatite, ialite, magadiite, kenyaite, etc.). In particular, the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of the layered mineral having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge) and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size. Further, among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.

  Also used are intercalation compounds of the above-mentioned layered minerals (pillar crystals, etc.), those subjected to ion exchange treatment, and those subjected to surface treatment (silane coupling treatment, compounding treatment with organic binder, etc.) can do.

  As the size of the flat lamellar mineral particles, the average particle diameter (maximum length of the particles) is less than 1 μm in the state of being contained in the layer (including the case where the swelling process and the dispersion peeling process have been performed). The aspect ratio is preferably 50 or more. When the particle size is in the above range, the continuity and flexibility in the planar direction, which are the characteristics of the thin layered particles, are imparted to the coating film, and it is difficult for cracks to occur, and a tough coating film can be obtained in a dry state. Moreover, in the coating liquid containing many particulate matters, sedimentation of particulate matter can be suppressed by the thickening effect of the layered clay mineral. When the particle diameter is larger than the above range, the coating film may be non-uniform, and the strength may be locally reduced. On the other hand, when the aspect ratio is not more than the above range, the number of tabular grains with respect to the addition amount is reduced, the viscosity is insufficient, and the effect of suppressing sedimentation of the particulate matter is reduced.

  The content of the layered mineral particles is preferably 0.1 to 30% by mass, and more preferably 1 to 10% by mass based on the entire layer. In particular, swellable synthetic fluorinated mica and smectite are preferable because they are effective even when added in a small amount. The layered mineral particles may be added as a powder to the coating solution, but in order to obtain a good degree of dispersion even with a simple preparation method (no need for a dispersion step such as media dispersion), the layered mineral particles are used alone. It is preferable to prepare the gel swollen in water and add it to the coating solution.

A silicate aqueous solution can also be used as the other additive material in the hydrophilic layer matrix constituting the hydrophilic layer. Alkali metal silicates such as silicate Na, silicate K, and silicate Li are preferred, and the SiO ₂ / M ₂ O ratio is in a range where the pH of the entire coating solution does not exceed 13 when silicate is added. It is preferable to select such that the inorganic particles are not dissolved.

  Further, an inorganic polymer or an organic-inorganic hybrid polymer by a so-called sol-gel method using a metal alkoxide can also be used. The formation of an inorganic polymer or an organic-inorganic hybrid polymer by the sol-gel method is described in, for example, “Application of the sol-gel method” (Sakuo Sakuo / Agne Jofusha) or is described in this document. Known methods described in the cited documents can be used.

  In the present invention, a water-soluble resin may be contained. Examples of water-soluble resins include polysaccharides, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, and conjugated diene polymer latex of methyl methacrylate-butadiene copolymer. Examples thereof include resins such as acrylic polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone. As the water-soluble resin used in the present invention, it is preferable to use a polysaccharide.

  As polysaccharides, starches, celluloses, polyuronic acids, pullulans and the like can be used, but cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, hydroxyethyl cellulose salts are particularly preferable, and sodium salts and ammonium salts of carboxymethyl cellulose are preferable. More preferred. This is because an effect of forming the surface shape of the hydrophilic layer in a preferable state can be obtained by including the polysaccharide in the hydrophilic layer.

  The surface of the hydrophilic layer preferably has a concavo-convex structure with a pitch of 0.1 to 20 μm like the aluminum grain of the PS plate, and this concavo-convex improves water retention and image area retention. Such a concavo-convex structure can be formed by adding an appropriate amount of a filler having an appropriate particle size to the hydrophilic layer matrix. However, the above-mentioned alkaline colloidal silica and the above-mentioned water-soluble solution are added to the hydrophilic layer coating solution. It is preferable that a structure having better printability can be obtained by forming a phase separation when the hydrophilic polysaccharide is applied and dried.

  The shape of the concavo-convex structure (such as pitch and surface roughness) is determined by the type and amount of alkaline colloidal silica, the type and amount of water-soluble polysaccharides, the type and amount of other additives, the solid content concentration of the coating solution, and the wetness. It is possible to appropriately control the film thickness, drying conditions, and the like.

  In the present invention, the water-soluble resin added to the hydrophilic matrix structure part is preferably present in a state where at least a part thereof is water-soluble and can be eluted in water. This is because even if it is a water-soluble material, when it is cross-linked by a cross-linking agent or the like and becomes insoluble in water, its hydrophilicity is lowered and printability may be deteriorated. Further, it may further contain a cationic resin. Examples of the cationic resin include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine or derivatives thereof, tertiary amino groups and quaternary ammonium groups. Examples thereof include acrylic resin and diacrylamine. The cationic resin may be added in the form of fine particles, and examples thereof include a cationic microgel described in JP-A-6-161101.

  In addition, the coating liquid used for coating the hydrophilic layer can contain a water-soluble surfactant for the purpose of improving the coatability, and a Si-based or F-based surfactant can be added. Although it can be used, it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains. The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass of the entire hydrophilic layer (solid content as the coating solution).

  The hydrophilic layer can contain a phosphate. In the present invention, since the hydrophilic layer coating solution is preferably alkaline, the phosphate is preferably added as trisodium phosphate or disodium hydrogen phosphate. By adding phosphate, the effect of improving the mesh opening at the time of printing can be obtained. The addition amount of phosphate is preferably 0.1 to 5% by mass, and more preferably 0.5 to 2% by mass as an effective amount excluding hydrate.

(Thermal image forming layer)
In the heat-sensitive image forming layer according to the present invention, by image-wise heating, the heat-sensitive image forming layer in the heated portion forms an ink-thickness image, and the heat-sensitive image forming layer in the non-heated portion is removed and is hydrophilic. The surface of the layer can be exposed to form an image as a printing plate.

  The removal of the thermal image forming layer is preferably performed on a printing press. That is, an embodiment in which the heat-sensitive image forming layer is a layer that can be developed on a printing press is preferable, and development on a printing press can be achieved by providing an image forming layer mainly composed of a blocked isocyanate compound as described above.

  “Developable on a printing press” means that the image forming layer in the non-image area can be removed by dampening water and / or printing ink in lithographic printing after exposure.

  The heating method includes a method using a heat source and a method using heat generated by light exposure such as a laser, but an image forming method using heat generated by light exposure such as laser is preferable.

  The heat-sensitive image forming layer contains a blocked isocyanate compound, and the heated part is a compound or substrate having a hydroxyl group having reactivity with the isocyanate group by generating an isocyanate group by dissociating the blocking agent of the blocked isocyanate compound. To form an image portion that is ink-inking.

(Photothermal conversion material)
The heat-sensitive image forming layer preferably contains a photothermal conversion material described later.

  By including a photothermal conversion material in the heat-sensitive image forming layer, for example, a printing plate material capable of image formation by an infrared laser can be obtained.

As the photothermal conversion material to be contained in the thermal image forming layer, an infrared absorbing dye is preferable. As the content of the infrared absorbing dye, depending on the degree of coloring of the dye with visible light, it is necessary to consider the trade-off between printing machine contamination during on-press development, but generally as a unit area of the printing plate material , 0.001 g / m ² or more, preferably less than 0.2 g / m ^2, more preferably less than 0.05 g / m ^2. Needless to say, it is preferable to use a pigment that is less colored with visible light.

  Specific examples of infrared absorbing dyes include 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 organic 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-1-280750, JP-A-1-293342, JP-A-2-2074, Kaihei 3-26593, JP-A-3-30991, JP-A-3-34891, JP-A-3-36093, JP-A-3-36094, JP-A-3-36095, JP-A-3-42281, JP-A-3-42281 Examples thereof include compounds described in JP-A-3-97589, JP-A-3-103476, and the like. These can be used alone or in combination of two or more.

  JP-A-11-240270, JP-A-11-265062, JP-A-2000-309174, JP-A-2002-49147, JP-A-2001-162965, JP-A-2002-144750, JP-A-2001-219667. The compounds described in (1) can also be preferably used.

  The heat-sensitive image forming layer according to the present invention is preferably formed by coating from an aqueous coating solution. In this case, the infrared absorbing dye to be contained is preferably water-soluble.

  When using a non-water-soluble infrared-absorbing dye, prepare a solution in which the infrared-absorbing dye is first dissolved in an organic solvent that is compatible with water, such as ethanol, and prepare an aqueous dispersion of the blocked isocyanate compound. It can also be used by adding to the dispersion liquid.

  In this case, the solubility of the infrared-absorbing dye is greatly reduced by changing from an organic solvent to a mixed solvent of water and an organic solvent, so that it precipitates in the dispersion. At this time, it is selected on the surface of the dispersed particles of the blocked isocyanate compound. Therefore, the water-dispersed particles of the blocked isocyanate compound carrying the photothermal conversion material on the surface can be obtained, and efficient image formation becomes possible.

  Moreover, in any step between the above-mentioned blocking of the isocyanate compound and water dispersion, an infrared absorbing dye dissolved in an organic solvent is added, and the organic solvent is removed as necessary after the water dispersion, so that the photothermal conversion material It is also possible to obtain water-dispersed particles of a blocked isocyanate compound having a supported therein.

  The thermal image forming layer may contain a surfactant. A surfactant such as Si-based or F-based can be used, but it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains. The content of this surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the heat-sensitive image forming layer (solid content as the coating solution).

  Further, it may contain an acid (phosphoric acid, acetic acid, etc.) or an alkali (sodium hydroxide, silicate, phosphate, etc.) for pH adjustment.

  The heat-sensitive image forming layer can contain a lubricant. By containing a lubricant, scratches on the heat-sensitive image forming layer (there is a concern that it may become dirty during printing) can be reduced.

  Examples of the lubricant include known waxes. Among them, fatty acid amide, fatty acid Ca, fatty acid Zn and the like having low ink setting properties are preferable.

  Since the heat-sensitive image forming layer is formed by coating with an aqueous coating solution, these lubricants are preferably added to the coating solution as an aqueous dispersion.

  The content of the lubricant is preferably 0.1 to 30% by mass, and more preferably 0.5 to 15% by mass of the thermal image forming layer.

(exposure)
The printing plate material according to the present invention preferably forms an image using laser light.

  Among these, it is particularly preferable to form an image by exposure with a thermal laser.

  For example, scanning exposure using a laser that emits light in the infrared and / or near infrared region, that is, emits light in the wavelength range of 700 to 1500 nm is preferable.

  A gas laser may be used as the laser, but it is particularly preferable to use a semiconductor laser that emits light in the near infrared region.

  As an apparatus suitable for scanning exposure, any apparatus may be used as long as it can form an image on the surface of a printing plate material in accordance with an image signal from a computer using the semiconductor laser.

  In general, (1) a printing plate material held by a flat plate holding mechanism is exposed two-dimensionally using one or a plurality of laser beams to expose the entire surface of the printing plate material. ) The printing plate material held along the cylindrical surface inside the fixed cylindrical holding mechanism is used in the circumferential direction of the cylinder (main scanning direction) using one or more laser beams from inside the cylinder. A method in which the entire surface of the printing plate material is exposed by moving in a direction perpendicular to the circumferential direction (sub-scanning direction) while scanning, and (3) printing held on the surface of a cylindrical drum that rotates about an axis as a rotating body The plate material is printed by moving in the direction perpendicular to the circumferential direction (sub-scanning direction) while scanning in the circumferential direction (main scanning direction) by rotating the drum using one or multiple laser beams from the outside of the cylinder. A method that exposes the entire plate material That. In particular, in an apparatus that performs exposure on a printing apparatus, the exposure method (3) is used.

(printing)
The image-exposed printing plate material can be subjected to general lithographic printing using dampening water and printing ink.

  As a printing method, it is particularly preferable to use a fountain solution that does not contain isopronol as the fountain solution (the content is not more than 0.5% by mass with respect to water).

  That is, in a preferred embodiment, the printing plate material of the present invention is subjected to image exposure with an infrared laser, developed with dampening water or dampening water and printing ink on a printing machine, and printed.

  The printing plate material after image formation is directly attached to the plate cylinder of the printing press, or the image forming is performed after the printing plate material is attached to the plate cylinder of the printing press, and the water supply roller and / or ink supply is performed while rotating the plate cylinder. By bringing the roller into contact with the printing plate material, it is possible to remove the non-image portion of the thermal image forming layer.

  The removal of the non-image area, a so-called on-press development method will be described below.

  The removal of the non-image part (unexposed part) of the heat-sensitive image forming layer on the printing press can be carried out by contacting a watering roller or an ink roller while rotating the plate cylinder, as in the following examples: Alternatively, it can be performed by various other sequences.

  In that case, the water amount may be adjusted by increasing or decreasing the amount of dampening water required for printing, and the water amount adjustment may be divided into multiple stages or steplessly. You may change it to.

  (1) As a sequence for starting printing, a watering roller is brought into contact with the plate cylinder to make one to several dozen rotations, then an ink roller is brought into contact with the plate cylinder to make one to several dozen rotations, and then Start printing.

  (2) As a sequence for starting printing, an ink roller is contacted to rotate the plate cylinder 1 to several tens of turns, then a watering roller is contacted to rotate the plate cylinder 1 to tens of rotations, Start printing.

  (3) As a sequence for starting printing, the watering roller and the ink roller are brought into contact with each other substantially simultaneously to rotate the plate cylinder 1 to several tens of times, and then printing is started.

  The heat-sensitive image forming layer according to the present invention is a layer obtained by applying and drying an aqueous dispersion of a specific blocked isocyanate compound. Therefore, even when stored in a relatively high temperature environment, Upper development is possible, and good image formation can be performed.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” represents “parts by mass” unless otherwise specified.

(Preparation of substrate 1)
An aluminum plate (material 1050, tempered H16) having a thickness of 0.24 mm was immersed in a 1% by mass sodium hydroxide aqueous solution at 50 ° C., dissolved so that the dissolved amount became 2 g / m ² , and washed with water. Then, it was immersed in 5 mass% nitric acid aqueous solution at 25 ° C. for 30 seconds, neutralized, and then washed with water.

Next, this aluminum plate was subjected to an electrolytic surface roughening treatment with an electrolytic solution containing hydrochloric acid 10 g / L and aluminum 0.5 g / L using a sine wave alternating current and a peak current density of 50 A / dm ^2. It was.

The distance between the electrode and the sample surface at this time was 10 mm. Electrolytic surface-roughening treatment is performed by dividing into 10 times, the quantity of electricity used in one treatment (at a positive polarity) was 60C / dm ^2, was treated quantity of electricity 600C / dm ² in total (at a positive polarity). In addition, a rest time of 4 seconds was provided between each surface roughening treatment.

After electrolytic surface roughening, it is immersed in a 1% by weight aqueous sodium hydroxide solution maintained at 50 ° C. and etched so that the amount of dissolution including the smut of the roughened surface becomes ² g / m ² , It was washed with water, then immersed in a 10% sulfuric acid aqueous solution maintained at 25 ° C. for 10 seconds, neutralized, and then washed with water. Next, anodization was performed in a 20% aqueous sulfuric acid solution under a constant voltage condition of 20 V so that the amount of electricity was 150 C / dm ^2, and further washed with water.

  Next, after squeezing the surface water after washing with water, it was immersed in a 0.1% by mass ammonium acetate aqueous solution (adjusted to pH 9 with Na hydroxide) maintained at 90 ° C. for 15 seconds, and further washed with water. The substrate 1 was obtained by immersing in a 0.1% by mass carboxymethylcellulose aqueous solution kept at 90 ° C. for 15 seconds, washing with water and then drying at 80 ° C. for 5 minutes. The surface roughness of the substrate 1 was 0.7 μm in Ra.

[Measurement method of surface roughness]
After depositing platinum rhodium with a thickness of 1.5 nm on the surface of the sample, using a non-contact three-dimensional roughness measuring apparatus manufactured by WYKO: RST plus, a 20-fold condition (measurement of 222.4 μm × 299.4 μm) Range) and processing the measurement data by applying a tilt correction and a media smoothing filter to obtain the Ra value. The measurement was carried out five times for one sample at different measurement locations, and the average was obtained as the Ra value.

(Preparation of base material 2)
An aluminum plate (material 1050, tempered H16) having a thickness of 0.24 mm was immersed in a 1% by mass sodium hydroxide aqueous solution at 50 ° C., dissolved so that the dissolved amount became 2 g / m ² , and washed with water. Thereafter, it was immersed in a 10% by mass nitric acid aqueous solution at 25 ° C. for 30 seconds, neutralized, and then washed with water. Subsequently, it dried at 100 degreeC for 3 minutes, and the base material 2 was obtained.

Example 1
(Preparation of blocked isocyanate compound aqueous dispersion)
Blocked isocyanate of organic solvent system in which trimethylolpropane adduct of tolylene diisocyanate is blocked with methyl ethyl ketoxime (solid content 55% by mass, solvent: mixed solvent of ethyl acetate and MIBK (methyl isobutyl ketone)): 364 parts by mass of toluene : Dissolved in 136 parts by mass.

  Next, 20 parts by mass of polyoxyethylene alkylphenyl ether as a dispersant was added to this solution, and after further adding 330 parts by mass of pure water while stirring, the mixture was vigorously stirred using a homogenizer. The oil phase was dispersed in the aqueous phase.

  Subsequently, the organic solvent was removed under reduced pressure to obtain a blocked isocyanate compound aqueous dispersion having a solid content of 40% by mass.

(Preparation of image forming layer coating solutions (1) to (14))
The raw materials having the respective compositions shown in the following table were sufficiently mixed and stirred and filtered to prepare image forming layer coating solutions (1) to (14) having a solid content of 5% by mass.

  Image forming layer coating solutions (1) to (14) composition (numbers without unit designation in the table represent parts by mass)

(Preparation of printing plate materials 1-14)
The prepared image forming layer coating liquids (1) to (14) were applied to the grained surface of the substrate 1 using a wire bar, and dried at 55 ° C. for 3 minutes.

The dry weight of the image forming layer was set to 0.4 g / m ² . Next, this was subjected to an aging treatment at 55 ° C. for 48 hours to obtain printing plate materials 1 to 14.

Image formation by infrared laser method Each printing plate material was wound around an exposure drum and fixed. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm was used for exposure, and an image was formed with 2400 dpi (dpi represents the number of dots per 2.54 cm) and 175 lines.

The exposed image includes a solid image, a 1 to 99% halftone dot image, and a 2400 dpi line-and-space thin line image. Exposure energy is varied from 100 mJ / cm ² to 50 mJ / cm ² by 400 mJ / cm ^2, and exposing an image of the above in the exposure energy Zorezore.

(Printing method)
Printing machine: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., coated paper, dampening solution: 2% by mass of Astro Mark 3 (manufactured by Nikken Chemical Laboratories), ink (Toyo King High Unity M Red manufactured by Toyo Ink Co., Ltd.) Used to print.

  The exposed printing plate material was directly attached to the plate cylinder, and 500 sheets were printed using the same printing conditions and printing sequence as the PS plate.

[Evaluation of printability]
The number of printed materials obtained from printing was determined to obtain a good image. A good image was defined as having no background stain and the density of the solid image portion exposed at 400 mJ / cm ² being 1.5 or more.

  At this time, if the density of the solid image portion is less than 1.5 even on the 500th printed matter due to poor ink depositability in the image area, the ink solidness is poor. If no image remained, the image formation was defective. The results are shown in Table 3.

[Sensitivity evaluation]
The 500th printed material was observed, and image formation sensitivity was evaluated for each of a solid image, a 3% halftone dot small dot image, and a line-and-space thin line image. The evaluation index was as follows. The results are shown in Table 3.

Solid image: Minimum exposure energy for image formation without blur Small dot image: 3% halftone dot image with no chipping and minimum energy formed with the same size of small dots Thin line image: No fine line breaks, more space As can be seen from Table 3, the printing plate material of the present invention has high sensitivity and excellent printability.

Example 2
Preparation of lower layer coating solution and hydrophilic layer coating solution The materials shown in the table below were sufficiently mixed and stirred and filtered to obtain a lower layer 3 coating solution having a solid content of 20% by mass.

  Coating solution composition for lower layer (solid content 20% by mass) (numerical values without unit description in the table indicate parts by mass)

  Next, the materials excluding the surfactants shown in the table below were mixed and dispersed for 10 minutes at 10,000 rotations using a homogenizer. Next, a surfactant was added thereto, and the mixture was weakly stirred and then filtered to obtain a hydrophilic layer coating solution having a solid content of 30% by mass.

  Coating liquid composition for hydrophilic layer (solid content: 30% by mass) (Numerical values without unit description in the table indicate parts by mass)

Preparation of hydrophilic layer-forming substrate The lower layer coating solution was applied to the substrate 2 using a wire bar and dried at 200 ° C for 30 seconds.

The dry weight of the lower layer was adjusted to 1.5 g / m ² .

Next, a hydrophilic layer coating liquid was applied onto the formed lower surface using a wire bar, and dried at 200 ° C. for 30 seconds to obtain a hydrophilic layer-forming substrate. The dry weight of the hydrophilic layer was adjusted to 3.0 g / m ² .

Preparation of image forming layer coating solutions (15) to (22) Blocked isocyanate aqueous dispersion: WB-700 (manufactured by Mitsui Takeda Chemical Co., Ltd., isocyanate compound: trimethylolpropane adduct of TDI (tolylene diisocyanate), blocking agent: 10.0 parts by mass of an oxime-based, dissociation temperature: 120 ° C., solid content of 44% by mass was diluted with 75.0 parts by mass of pure water while stirring.

  Next, while stirring this, 15.0 parts by mass of a 4% by mass IPA (isopropyl alcohol) solution of a water-insoluble infrared absorbing dye having the following structure is dropped little by little to form a blocked isocyanate compound and the following water-insoluble infrared absorbing dye. An aqueous dispersion (solid content: 5% by mass) was obtained.

  The water-insoluble infrared-absorbing dye having the following structure dissolves in IPA, but does not dissolve in the water / IPA mixed solvent having the above ratio, so that the dye precipitates immediately after the IPA solution is dropped. In that case, since it is thought that a pigment | dye selectively precipitates on the surface of the blocked isocyanate compound which has disperse | distributed, the said water dispersion is the aqueous system of the dispersion | distribution which the blocked isocyanate compound and the water-insoluble infrared rays absorption pigment | dye combined. It is considered to be a dispersion.

  Next, each material of each composition shown in the following table was sufficiently mixed and stirred and filtered to prepare image forming layer coating solutions (15) to (22).

  Composition (15) to (22) composition for image forming layer (numbers without unit designation in the table represent parts by mass)

Preparation of printing plate materials 15 to 22 Image forming layer coating solutions (15) to (22) were respectively applied to the hydrophilic layer surface of the prepared hydrophilic layer forming substrate, and dried at 55 ° C. for 1 minute.

The dry weight of the image forming layer was adjusted to 0.3 g / m ² . Next, this was subjected to an aging treatment at 55 ° C. for 48 hours to obtain printing plate materials 15 to 22.

[Sensitivity evaluation]
Each printing plate material is exposed and printed in the same manner as in Example 1, and the image formation sensitivity of each solid image, 3% halftone dot image, and line-and-space thin line image of each printing plate material is increased. evaluated. The results are shown in Table 7. From this result, each printing plate material appropriate sensitivity is shown in Table 7 as the highest exposure energy among the above three types of image forming sensitivities.

Image formation with appropriate sensitivity by infrared laser method Each printing plate material was wound around an exposure drum and fixed. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm was used for exposure, and an image was formed with 2400 dpi (dpi represents the number of dots per 2.54 cm) and 175 lines.

  The exposed image includes a solid image and a 1 to 99% halftone dot image. The exposure energy was the exposure energy with appropriate sensitivity of each printing plate material shown in Table 7.

(Printing method)
Printing machine: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., high-quality paper (Shiraoi), dampening water: 2% by mass of Astro Mark 3 (manufactured by Nikken Chemical Laboratories), ink (Toyo King High Unity manufactured by Toyo Ink Co., Ltd.) M red) was used for printing.

  The exposed printing plate material was directly attached to the plate cylinder, and up to 30,000 sheets were printed using the same printing conditions and printing sequence as the PS plate.

[Evaluation of printing durability]
The printed matter was sampled every 1000 prints, and the degree of image deterioration between the 3% halftone dot image portion and the solid image portion was confirmed. For the 3% halftone dot image portion, the point at which halftone dot breakage was 30% or more when observed with a loupe was defined as the printing end point, and the number of printed sheets was defined as the number of printed sheets.

  With respect to the solid image portion, the printing end point was determined when the blur was confirmed visually, and the number of printed sheets was defined as the number of printed sheets. The results are shown in Table 8.

  From Tables 7 and 8, it can be seen that the printing plate material of the present invention can form an image with high sensitivity, that is, with low exposure energy, and high printing durability can be obtained even with an image formed with low exposure energy. .

Claims (5)

In a printing plate material having a thermosensitive image forming layer on a substrate having a hydrophilic surface, the thermosensitive image forming layer contains (A) a water-insoluble blocked isocyanate compound and (B) a water-soluble crosslinkable compound, (B) The printing plate, wherein the water-soluble crosslinkable compound is (b1) a guanidine compound or (b2) a compound having a hydroxyl group and having an epoxy group, a carboxyl group, a carbonyl group or an acetoacetyl group material. The printing plate material according to claim 1, wherein the water-soluble crosslinkable compound (B) has a molecular weight of 120 to 30,000. The printing plate material according to claim 1, wherein the heat-sensitive image forming layer is a layer that can be developed on a printing press. The printing plate material according to any one of claims 1 to 3, wherein the heat-sensitive image forming layer contains (A) 30% by mass to 90% by mass of the water-insoluble blocked isocyanate compound. The printing plate material according to any one of claims 1 to 4, wherein the (A) water-insoluble blocked isocyanate compound is a compound obtained by adding a blocking agent and a low molecular weight polyol to tolylene diisocyanate. .