JP2015077692A - Heat-sensitive-type planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive-type planographic printing plate improved in stain recovery while keeping plate durability.SOLUTION: A heat-sensitive-type planographic printing plate has an image-forming layer containing thermoplastic resin, thermofusion substance and water-soluble polymer compounds on a support, and uses a heated part of the image-forming layer as an image area and a non-heated part of the image-forming layer as a non-image area. The image-forming layer contains a silane coupling agent.

Description

  The present invention relates to a heat-sensitive lithographic printing plate using an image-forming layer that undergoes phase conversion by heat, and relates to a heat-sensitive lithographic printing plate that does not require layer removal processing in a conventional ablation method or on-machine development method.

  In recent years, various plate making methods of planographic printing plates using various digital printers have been proposed with the development of computers and peripheral devices. For example, Japanese Patent Application Laid-Open Nos. 6-138719 and 6-250424 disclose plate making using a dry electrophotographic laser printer, and Japanese Patent Application Laid-Open No. 9-58144 includes on-demand using hot-melt ink. A plate making by an ink jet printer, and a plate making by a thermal printer using a thermal transfer ink ribbon are known from JP-A 63-166590.

  The plate making method using the printer as described above is largely divided from the conventional optical mode type using a visible light laser or the like, and is not subject to safety light restrictions in handling, and thus has a great advantage in this respect. . In addition, printing plates made by these plate making methods are collectively referred to as processless printing plates because they do not require any post-exposure development processing that is normally used in conventional optical mode types.

  However, each of the above processless printing plates forms a printing plate by transferring and imparting a grease-sensitive (that is, lithographic printing ink deposition property) recorded image to the surface of a support provided with a water retention layer. Because of this method, there were the following problems.

1) Since a layer for forming an image is hydrophilic, adhesion of toner, ink or the like is not sufficient. For example, a transfer toner image density is insufficient, or white spots are generated in a transfer image.
2) A problem that the transfer image is not sufficiently fixed, the printing durability is lowered, and in particular, a part of a small point character or a halftone image in a highlight portion is lost.
3) A problem that a small background is generated due to irregular transfer of a small amount of toner to the non-image area or rubbing of the thermal transfer ink ribbon.

  On the other hand, a thermal lithographic printing plate or the like in which an image forming layer containing a thermoplastic resin or a heat-meltable substance is provided on a support, and an oleophilic image portion is obtained by thermal printing with a thermal head or an infrared laser Has also been proposed.

  For example, Japanese Patent Application Laid-Open No. 58-199153 (Patent Document 1) or Japanese Patent Application Laid-Open No. 59-174395 (Patent Document 2) directly draws heat on an image forming layer with a thermal head or the like without using a thermal transfer ribbon or the like. A heat-sensitive lithographic printing plate from which an oleophilic image area can be obtained is described. In JP 2000-190649 A (Patent Document 3) and JP 2000-301846 A (Patent Document 4), thermal lithographic printing in which an oleophilic image portion is obtained by direct heat drawing with an infrared laser or the like. A version is also listed. Each of these is a phase change type printing plate, and the part that was originally hydrophilic causes phase change and changes to hydrophobic (lipophilic). In normal lithographic printing, both water and ink are simultaneously supplied to the oleophilic image area obtained as described above, the image area accepts colored ink, and the other non-image areas are hydrophilic. Accept water selectively and not accept ink. Printing is performed by transferring the ink received on the image portion onto a printing medium such as paper.

  However, the above-described heat-sensitive lithographic printing plate using phase conversion uses the heated portion of the image forming layer as the image portion and the non-heated portion of the image forming layer as the non-image portion. And also serves as a non-image part. For this reason, even with the same heat-sensitive lithographic printing plate, a printing plate that forms an image portion and a non-image portion by so-called debris processing such as a conventional ablation method or on-machine development method (for example, developing with water or a dampening solution) Unlike heat-sensitive lithographic printing plates, which remove the non-heated image-forming layer by processing and expose the hydrophilic layer provided between the image-forming layer and the support) Contains plastic resin and hot-melt material. That is, since the debris treatment is not performed at all, the coated film is used for printing as it is regardless of whether it is a heating part or a non-heating part. For this reason, increasing the oil sensitivity (lipophilicity) of the heated part has the contradictory tendency of sacrificing hydrophilicity on the other hand, and it is extremely difficult to improve printing durability and stain resistance in a balanced manner. Met.

  In order to improve the problems as described above, in JP-A-11-95417 (Patent Document 5), printing durability and water retention can be achieved by using a crosslinked hydrophilic resin such as polyvinyl alcohol or carboxymethyl cellulose in the image forming layer. However, the level of oleophilicity in the image area is low and the difference between lipophilicity / hydrophilicity is not sufficient. . JP-A-2000-75471 (Patent Document 6) uses a thermoplastic resin, a wax dispersion, a water repellent or the like as a hydrophobic substance, and uses gelatin, polyvinyl alcohol or the like as a hydrophilic substance. However, the difference in lipophilicity / hydrophilicity was not sufficient. Further, JP-A No. 2001-96710 (Patent Document 7) discloses a lithographic printing plate on which an image is formed by heat-meltable particles in which a hydrophilic material is physically coated and fixed. JP-A No. 2010-234724 (Patent Document 8) discloses a heat-sensitive lithographic printing plate having an image forming layer containing a specific thermoplastic resin and a water-soluble polymer compound. However, the balance between printing durability and stain resistance is further improved. In particular, there has been a demand for an improvement in so-called stain recovery, in which when the soil is soiled, an excessive amount of dampening water is applied to recover the soil normally.

  On the other hand, in order to improve the adhesion between the heat-sensitive layer of the waterless lithographic printing plate and the silicone rubber layer, a silane coupling agent layer is provided on the heat-sensitive layer in Japanese Patent Application Laid-Open No. 09-086063 (Patent Document 9). Have been described. Japanese Patent Application Laid-Open No. 2005-231232 discloses that a printing layer can be improved by providing a hydrophilic layer containing a silane coupling agent on an aluminum support and using a heat-sensitive image forming layer on the hydrophilic layer. Patent Document 10). Further, on the support, a particle that absorbs radiation represented by metal particles and starts the self-heating reaction and the particles are covered, and the functional group that changes from hydrophobic to hydrophilic by the self-heating reaction (for example, A heat-sensitive lithographic printing plate containing a binder obtained by reacting a compound having a sulfonic acid ester group or an alkoxyalkyl ester group) with a silane coupling agent can achieve both sensitivity and stain resistance. It is described in JP-A-11-268439 (Patent Document 11).

JP 58-199153 A JP 59-174395 A JP 2000-190649 A Japanese Patent Laid-Open No. 2000-301846 JP-A-11-95417 JP 2000-75471 A JP 2001-96710 A JP 2010-234724 A JP 09-086063 A JP 2005-231232 A JP-A-11-268439

  An object of the present invention is to provide a heat-sensitive lithographic printing plate having improved stain recovery properties while maintaining printing durability.

  The object of the present invention is to have an image forming layer containing a thermoplastic resin, a heat-meltable substance and a water-soluble polymer compound on a support, and the heated portion of the image forming layer is used as an image portion and the image forming layer. This is achieved by a heat-sensitive lithographic printing plate using the non-heated portion as a non-image portion, wherein the image-forming layer contains a silane coupling agent.

  According to the present invention, it is possible to provide a heat-sensitive lithographic printing plate having improved stain recovery while maintaining printing durability.

  The heat-sensitive lithographic printing plate of the present invention has an image forming layer containing a thermoplastic resin, a heat-meltable substance, and a water-soluble polymer compound. When the image-forming layer is heated and drawn with a thermal head or infrared laser, the part to which heat is applied is hydrophobic because the thermoplastic resin buried in the water-soluble polymer compound and the hot-melt material melt and ooze out to the extreme surface of the layer It becomes possible to accept ink at the time of printing. In the portion where heat is not applied, the thermoplastic resin and the heat-meltable substance remain buried in the water-soluble polymer compound, and the hydrophilicity inherent in the image forming layer is maintained. Then, lithographic printing can be performed by utilizing the difference between the hydrophobicity and the hydrophilicity.

  The silane coupling agent contained in the image forming layer of the heat-sensitive lithographic printing plate of the present invention is preferably an alkoxysilane compound having a reactive functional group, such as vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane. Alkoxysilane compounds having a vinyl group, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxy Alkoxysilane compounds containing an epoxy group such as propyltriethoxysilane, alkoxysilane compounds having a styryl group such as p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimeth Alkoxysilane compounds having a methacryloxy group such as silane, 3-methacryloxypropylmethyldiethoxysilane and 3-methacryloxypropyltriethoxysilane, alkoxysilane compounds having an acryloxy group such as 3-acryloxypropyltrimethoxysilane, N- 2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3 -Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N- (vinyl N-diyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride and other alkoxysilane compounds having an amino group, 3-ureidopropyltriethoxysilane and other alkoxysilane compounds having a ureido group, 3-chloropropyltri Alkoxysilane compounds having a chloropropyl group such as methoxysilane, alkoxysilane compounds having a mercapto group such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane, sulfides such as bis (triethoxysilylpropyl) tetrasulfide Alkoxy silane compounds having a group, alkoxy silane compounds having an isocyanate group such as 3-isocyanatopropyltriethoxy silane, and imidazole groups such as imidazole silane Examples thereof include a alkoxysilane compound, and among these, an alkoxysilane compound containing an epoxy group and an alkoxysilane compound containing an amino group are particularly preferable.

  The content of the silane coupling agent in the image forming layer is preferably 0.03 to 3% by mass with respect to the total solid content of the image forming layer. More preferably, it is 0.3-1.5 mass%. Moreover, a silane coupling agent may be used independently and may be used in combination of 2 or more type.

  The image forming layer of the present invention contains a water-soluble polymer compound. Examples of the water-soluble polymer compound include cellulose derivatives such as hydroxyethyl cellulose and carboxymethyl cellulose, starch and derivatives thereof, polysaccharides such as glycogen, agarose, pectin, dextran, and pullulan, gelatin, casein, sodium alginate, polyvinyl alcohol, polyvinyl Examples include pyrrolidone, styrene / maleic acid copolymer salt, and styrene / acrylic acid copolymer salt. These water-soluble polymer compounds can be used alone or in combination of two or more, but gelatin can be particularly preferably used. The content of the water-soluble polymer compound in the image forming layer is preferably 5 to 55% by mass with respect to the total solid content of the image forming layer.

  In the present invention, the thermoplastic resin contained in the image forming layer is a solid water-insoluble organic polymer compound that is made of a chain polymer and exhibits plasticity upon heating, and is a water-based coating liquid as a coating liquid for the image forming layer. In the case of using an aqueous dispersion, an aqueous dispersion (emulsion, latex) is preferable. Typical examples are synthetic rubber latex including modified products such as styrene butadiene copolymer, acrylonitrile butadiene copolymer, methyl methacrylate butadiene copolymer, styrene acrylonitrile butadiene copolymer, styrene methyl methacrylate butadiene copolymer. Styrene maleic anhydride copolymer, methyl vinyl ether maleic anhydride copolymer, polyacrylic acid copolymer, polystyrene, styrene / acrylic acid ester copolymer, polyacrylic acid ester, polymethacrylic acid ester, acrylic acid ester An aqueous dispersion such as a / methacrylic acid ester copolymer and a low melting point polyamide resin can also be used. These thermoplastic resins can be used alone or in combination of two or more. Synthetic rubber latex is preferably used as the thermoplastic resin because of its affinity with the printing ink vehicle (binder component). Such synthetic rubber latex is preferably of a type that self-crosslinks by heat from the viewpoint of printing durability. The self-crosslinking type means that it is possible to form a three-dimensional network by heat without the presence of a crosslinking agent. When producing such a synthetic rubber latex, a carboxyl group, a hydroxyl group, or a methylol is used as a copolymerization component. It can be obtained by the presence of a reactive functional group such as an amide group, an epoxy group, a carbonyl group, or an amino group. Moreover, as a reactive functional group, a carboxyl group, a hydroxyl group, and an amino group are preferable, and especially the synthetic rubber latex which has a carboxyl group as a reactive functional group is preferable. As a result, the image area is self-crosslinked to obtain good printing durability, and at the same time, the non-image area that is not heated is preferable because excellent water retention is obtained. A particularly preferred synthetic rubber latex is a carboxy-modified styrene butadiene copolymer. The preferable content of the thermoplastic resin is preferably 5 to 50% by mass, more preferably 20 to 45% by mass, based on the total solid content of the image forming layer.

  Moreover, in order to make it easy to express the effect of melting and fusing by heat, it is preferable to use a thermoplastic resin having a glass transition temperature of 50 to 150 ° C, more preferably 55 to 120 ° C. If the glass transition temperature is less than 50 ° C., a phase change occurs in a liquid state during the production process, and the oleophilicity may develop in the non-image area, which may cause printing smudges. When the temperature exceeds 150 ° C., the thermoplastic resin hardly melts, and it may be difficult to form a strong image with a relatively small output laser or a small thermal printer.

  Examples of the heat-meltable substance contained in the image forming layer in the present invention include, for example, waxes such as carnauba wax, microcrystalline wax, paraffin wax, polyethylene wax, lauric acid, stearic acid, oleic acid, palmitic acid, behenic acid, In addition to metal salts of higher fatty acids such as montanic acid, esters and amides, naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl, 4-allyloxybiphenyl, m-terphenyl, Polyether compounds such as 2-bis (3-methylphenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, dioxalate (P-Chlorobenzyl) S Carbonate or oxalate diester derivatives such as Le, and the like. These can be used alone or in admixture of two or more, and a hot-melt material having a melting point of 50 to 150 ° C. is preferably used. If the melting point is less than 50 ° C., it will melt during the production process, which may cause soiling of the printed matter. On the other hand, when it exceeds 150 ° C., it is difficult to melt by applying heat from a thermal head or the like, and the lipophilicity may be poor. The preferable content of the heat-meltable substance in the image forming layer is preferably 1 to 50% by mass, more preferably 5 to 30% by mass with respect to the total solid content of the image forming layer.

  Of the above hot-melt materials, compounds other than waxes, fatty acids and esters thereof, and amides are preferably used after being subjected to a fine dispersion treatment in order to increase reactivity by heat. As a fine dispersion treatment method, a bead mill such as a roll mill, a colloid mill, a ball mill, an attritor or a sand mill, which is a wet dispersion method generally used at the time of producing a paint, can be used. In the bead mill, ceramic beads such as zirconia, titania and alumina, metal beads such as chrome and steel, glass beads and the like can be used. The dispersed particle diameter is preferably from 0.1 to 1.2 μm in median diameter, particularly preferably from 0.3 to 0.8 μm. The median diameter is the particle diameter (cumulative average diameter) at which the cumulative curve becomes 50% when the total curve of one population of particles is 100%, and the particle size distribution is evaluated. As one of the parameters to be measured, it can be measured using a laser diffraction / scattering particle size distribution measuring apparatus LA920 (manufactured by Horiba, Ltd.) or the like.

  The image forming layer of the heat-sensitive lithographic printing plate of the present invention preferably contains a crosslinking agent in order to improve the film strength, adhesive strength, etc. of the image forming layer. As examples of the crosslinking agent, melamine resin, epoxy resin, polyisocyanate compound, aldehyde compound, chromium alum, divinyl sulfone, and the like can be suitably used. A particularly preferred crosslinking agent is divinyl sulfone. In addition, the necessary water resistance and mechanical strength can be obtained, and from the viewpoint of avoiding characteristic fluctuations over time when stored, the amount of the crosslinking agent is based on the solid content of the water-soluble polymer compound contained in the image forming layer. The content is preferably 1 to 30% by mass, and more preferably 2 to 20% by mass.

  In the heat-sensitive lithographic printing plate of the present invention, a developer or a color former (electron donating property) such as a phenol derivative or an aromatic carboxylic acid derivative used in general heat-sensitive recording paper and pressure-sensitive recording paper for ensuring visibility. Dye precursor).

  Specific examples of the developer include 4-cumylphenol, hydroquinone monobenzyl ether, 4,4'-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4'- Dihydroxydiphenyl-2,2-butane, 4,4′-dihydroxydiphenylmethane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) heptane, bis (4 -Hydroxyphenylthioethoxy) methane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α -Methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4′-hydride) Xylphenyl) ethyl] benzene, 4,4'-dihydroxydiphenyl sulfide, bis (4-hydroxy-3-methylphenyl) sulfine, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone 2,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-4'-benzyloxyphenylsulfone, 4-hydroxy-3 ', 4'-tetramethylenebiphenylsulfone, 3,4-dihydroxyphenyl-p-tolylsulfone, 4,4'-dihydroxybenzophenone, benzyl 4-hydroxybenzoate, N, N'-di-m-chlorophenylthiourea, N- (Fe Phenolic compounds such as (noxyethyl) -4-hydroxyphenylsulfonamide, zinc 4- [3- (p-tolylsulfonyl) propyloxy] salicylate, 4- [2- (p-methoxyphenoxy) ethyloxy] zinc salicylate, 5- [P- (2-p-methoxyphenoxyethoxy) cumyl] zinc salts of aromatic carboxylic acids such as zinc salicylate and zinc p-chlorobenzoate, and organic acidic substances such as antipyrine complexes of zinc thiocyanate The

  Specific examples of the color former (electron-donating dye precursor) include (1) 3,3′-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (Crystal Violet lactone), 3,3′-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p -Dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis ( 1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethyla Nophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3- p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like: (2) 4,4′-bis-dimethylaminobenzhydrin benzyl ether as a diphenylmethane compound, N-halophenyl leucooramine, N-2,4,5-trichlorophenyl leucooramine, etc .: (3) As xanthene compounds, rhodamine B-anilinolactam, rhodamine Bp-nitroanilinolactam, rhodamine B -P-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3- Ethylamino-7-octylaminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-ethyl- Tolylamino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, etc .: (4) thiazine compounds As benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue (5) As spiro compounds, 3-methyl-spiro-dinaphthopyrans, 3-ethyl-spiro-dinaphthopyrans, 3,3'-dichloro-spiro-dinaphthopyrans, 3-benzyl-spiro-dinaphthopyrans, 3-methylnaphtho- ( 3-methoxy-benzo) -spiropyran, 3-propyl-spiro-dibenzopyran and the like. These may be used alone or in combination of two or more.

  Furthermore, in the present invention, a photothermal conversion substance can be blended in the image forming layer. By using a photothermal conversion substance, writing with active light such as an infrared laser as well as a thermal head is possible. As an example of the photothermal conversion substance, a material that efficiently absorbs light and converts it into heat is preferable. Depending on the light source used, for example, when a semiconductor laser emitting near infrared light is used as the light source, Near-infrared light absorbers having an absorption band outside are preferable, for example, organic materials such as carbon black, cyanine dyes, polymethine dyes, azurenium dyes, squarylium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes Examples thereof include metal compounds such as compounds, phthalocyanine-based, azo-based, and thioamide-based organometallic complexes, iron powder, graphite powder, iron oxide powder, lead oxide, silver oxide, chromium oxide, iron sulfide, and chromium sulfide.

  The image forming layer of the heat-sensitive lithographic printing plate of the present invention can contain inorganic pigments such as silicon dioxide, titanium dioxide, aluminum hydroxide, calcium carbonate, zinc oxide, and barium sulfate. good. In particular, better printability may be obtained by using zinc oxide or barium sulfate, and the total amount of inorganic pigment used should be 0.1 to 5% by mass relative to the total solid content of the image forming layer. Is preferred.

  In addition, preservatives, surfactants, antifoaming agents, leveling agents, pH adjusting agents, other coating aids, and the like can be added to the image forming layer of the present invention as necessary.

  The image forming layer of the present invention can be divided not only into a single layer but also into a multilayer structure. In that case, the ratio of the mass of the thermoplastic resin to the mass of the water-soluble polymer compound in the image forming layer close to the support is preferably higher than the ratio of the outermost image forming layer. The silane coupling agent can be added either alone or both of the image forming layer close to the support and the outermost image forming layer.

The image forming layer of the heat-sensitive lithographic printing plate of the present invention has an overall dry solid content of ² to 12 g / m ² from the viewpoints of printing durability of image areas, water resistance of non-image areas and mechanical strength. It is preferable that it exists in. As a coating method in the case where the image forming layer is a multilayer, there are a method of applying and stacking sequentially, a method of simultaneous multi-layer coating by a slide hopper method, etc., but either method may be used.

  As the support of the heat-sensitive lithographic printing plate of the present invention, a water-resistant support is used, but a water-resistant support such as a plastic film, resin-coated paper, and water-resistant paper can be preferably used. Specifically, plastic films such as polyolefins such as polyethylene and polypropylene, polyethersulfone, polyester, poly (meth) acrylate, polycarbonate, polyamide, and polyvinyl chloride, and resin-coated paper with these plastics laminated or coated on the surface, melamine Paper that has been made water resistant by a wet paper strength agent such as formaldehyde resin, urea formaldehyde resin, or epoxidized polyamide resin can be suitably used.

Next, a plate making method using the above-described heat-sensitive lithographic printing plate of the present invention will be described. The heat-sensitive lithographic printing plate of the present invention can be suitably used when making a plate using a thermal head. As such an apparatus, a line printer using a thick film or thin film line head, a serial printer using a thin film serial head, or the like can be used. The recording energy density is preferably 10 to 100 mJ / mm ² , and the head image recording density is preferably 300 dpi or more in order to obtain a relatively high quality output image.

  EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited by this description. In addition, unless otherwise indicated,% and a part in the following description show mass ratio.

(Preparation of heat-sensitive lithographic printing plates of Examples 1 to 7 and Comparative Example 1)
The following image-forming layer coating solution is applied to one side of a polyethylene resin-coated paper having a thickness of about 180 μm and laminated on both sides by a slide hopper coating method at a moisture application amount of 40 g / m ² and dried to form an image-forming layer. The heat-sensitive lithographic printing plates of Examples 1 to 7 and Comparative Example 1 were obtained.
<Image forming layer coating solution>
Gelatin 1.0 part Polyvinyl alcohol: PVA505 0.1 part (manufactured by Kuraray Co., Ltd., saponification degree 73.5 mol%, polymerization degree 500)
Carboxylated SBR: Luck Star 7132C (solid content conversion) 2.5 parts (DIC Corporation, Tg = about 60 ° C.)
Color developing agent mixed slurry 7.5 parts Surfactant (0.5% solution) 0.5 part Divinyl sulfone hardener (5% solution) 3.0 parts Silane coupling agent (addition compounds and number of parts are listed in Table 1) )
The total amount was 40 parts with water.

In Table 1, additive compounds S-1, S-2, S-3, S-4, and S-5 are the following compounds, and the number of added parts is parts by mass.
S-1: 3-glycidoxypropyltrimethoxysilane S-2: 3-glycidoxypropyltriethoxysilane S-3: 3-glycidoxypropylmethyldiethoxysilane S-4: 3-aminopropyltrimethoxy Silane S-5: 3-aminopropyltriethoxysilane

The color former mixed slurry used for the image forming layer coating solution was prepared in advance by the following preparation method.
<Preparation of color former mixed slurry>
Material a (hot meltable substance): 1,2-bis (3-methylphenoxy) ethane (manufactured by Sanko Co., Ltd .: KS-232)
Material b: 4-hydroxy-4'-isopropoxy diphenyl sulfone (Nippon Soda Co., Ltd. product: D-8)
Material c: 3-dibutylamino-6-methyl-7-anilinofluorane (manufactured by Yamamoto Kasei Co., Ltd .: ODB2)

  The above materials a, b, and c are individually finely dispersed in a small dyno mill (bead mill) to 0.7 μm using zirconia beads to prepare dispersions each having a solid content concentration of about 30%. Dispersion a, Dispersion b, and Dispersion c. A color former mixed slurry was prepared by mixing 3 parts of dispersions a and b with 1 part of dispersion c at room temperature.

  After coating with the above moisture application amount, the coating film was immediately gelled with cold air at 3 ° C., and then dried with hot air at 30 ° C. After drying, the thermosensitive lithographic printing plates of Examples 1 to 7 and Comparative Example 1 were obtained by heating for 7 days using a thermo-hygrostat adjusted to a temperature of 40 ° C./humidity of 40%.

The thermal lithographic printing plate produced as described above was subjected to image output (recording energy density 70 to 100 mJ / mm ² ) using a thermal digital printer for CTP (Thermal Digiplater TDP-459: 1200 dpi / 120 lpi manufactured by Mitsubishi Paper Industries). , Electric capacity 330W), and a printing plate was prepared. Using this printing plate, printability was evaluated by the following method.

<Evaluation of printing durability>
RYOBI MAGICS Co., Ltd. offset printing machine RYOBI3200CCD is used for the printing machine, DIC Corporation's New Champion F gloss ink H is used for the ink, and SLM-OD 10 made by Mitsubishi Paper Industries Co., Ltd. is used for the dampening liquid. Printing was performed with the plate mounted with a 50 μm-thick PET film sandwiched between the plate and the plate cylinder. Printing was started by performing an etching process using a 25% diluted solution of SLM-OD30 manufactured by Mitsubishi Paper Industries Co., Ltd. immediately before the start of printing. In the evaluation of printing durability, the number of prints that could not be printed due to a missing image was determined using the following evaluation criteria. The results are shown in Table 2.
<Evaluation criteria for printing durability>
○: More than 2,000 sheets △: Less than 2,000 sheets

<Soil recovery evaluation>
RYOBI MAGICS Co., Ltd. offset printing machine RYOBI3200CCD is used for printing, DIC Corporation's New Champion S Gloss ink is used for ink, and SLM-OD made by Mitsubishi Paper Industries Co., Ltd. is used for dampening liquid. Printing was started using the same dampening solution as an etching solution. As the stain recovery evaluation, 1000 sheets were printed, the printing machine was stopped for 10 minutes, and the number of sheets until the ink could be removed from the non-image area on the printed paper after restarting was evaluated. The results are shown in Table 2.
<Soil recovery evaluation>
◎: 30 sheets or less ○: 31 sheets or more and less than 50 sheets △: 50 sheets or more

(Preparation of heat-sensitive lithographic printing plates of Examples 8 to 17 and Comparative Example 2)
Applying the coating liquid of the following image forming layer (a) and image forming layer (b) to one side of a polyethylene resin-coated paper with a thickness of about 180 μm with both sides laminated by slide hopper coating method. So that the image forming layer (a) is 30 g / m ² and the image forming layer (b) is 10 g / m ² so that the image forming layer (a) and the image forming layer (b) are formed from the support side. The layers were simultaneously applied and dried to obtain heat-sensitive lithographic printing plates of Examples 8 to 17 and Comparative Example 2.
<Image forming layer (a) coating solution>
Gelatin 0.7 parts (Kuraray Co., Ltd., saponification degree 73.5 mol%, polymerization degree 500)
Carboxylated SBR: Luck Star 7132C (solid content conversion) 1.35 parts (manufactured by DIC Corporation, Tg = about 60 ° C.)
Color developing agent mixed slurry 7.0 parts Surfactant (0.5% solution) 0.4 parts Divinylsulfone hardener (5% solution) 2.0 parts Silane coupling agent (addition compounds and number of parts are listed in Table 3) )
The total amount was 30 parts with water.

<Image forming layer (b) coating solution>
Gelatin 0.3 part Carboxylated SBR: Luckstar 7132C (converted to solid amount) 0.27 part (manufactured by DIC Corporation, Tg = about 60 ° C.)
Coloring agent mixed slurry 0.3 part Divinylsulfone hardener (5% solution) 0.5 part Surfactant (0.5% solution) 0.2 part Paraffin wax: Hydrin L-703 (solid amount conversion) 0. 03 parts Divinylsulfone hardener (5% solution) 0.8 parts Silane coupling agent (addition compound and number of parts are listed in Table 3)
The total amount was 10 parts with water.

  In Table 3, additive compounds S-1, S-2, S-3, S-4, and S-5 are as described above, and the number of added parts is parts by mass.

  The color former mixed slurry used for the image forming layer (a) coating liquid and the image forming layer (b) coating liquid was prepared in the same manner as the previous color mixed slurry.

  After two layers were simultaneously applied at the moisture application amount, the coating film was immediately gelled with cold air at 3 ° C., and then dried with hot air at 30 ° C. After drying, the thermosensitive lithographic printing plates of Examples 8 to 17 and Comparative Example 2 were obtained by heating for 7 days using a thermo-hygrostat adjusted to a temperature of 40 ° C./humidity of 40%.

The thermal lithographic printing plate produced as described above was subjected to image output (recording energy density 70 to 100 mJ / mm ² ) using a thermal digital printer for CTP (Thermal Digiplater TDP-459: 1200 dpi / 120 lpi manufactured by Mitsubishi Paper Industries). , Electric capacity 330W), and a printing plate was prepared. Using this printing plate, printability was evaluated by the following method.

<Evaluation of printing durability>
Printing was performed and evaluated in the same manner as the previous printing durability evaluation. The results are shown in Table 4.

<Soil recovery evaluation>
Printing and evaluation were performed in the same manner as in the previous stain recovery evaluation. The results are shown in Table 4.

  As can be seen from the results shown in Tables 2 and 4, it can be seen that the present invention provides a heat-sensitive lithographic printing plate with improved stain recovery while maintaining printing durability.

Claims (1)

  An image forming layer containing a thermoplastic resin, a heat-meltable substance and a water-soluble polymer compound is provided on a support, and the heated portion of the image forming layer is an image portion and the non-heated portion of the image forming layer is a non-image A heat-sensitive lithographic printing plate used as a part, wherein the image forming layer contains a silane coupling agent.