JP2012162006A - Heat-sensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive lithographic printing plate having superior printing durability and stain resistance without requiring debris treatment.SOLUTION: The heat-sensitive lithographic printing plate includes at least two image forming layers containing a water-soluble polymer compound and thermoplastic resin on a supporting body. The image forming layer farthest from the supporting body contains at least one kind selected from paraffin wax, montanoic ester wax, and zinc stearate.

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 such as a conventional ablation method or an on-machine development method.

  In recent years, various plate making methods of lithographic printing plates using various digital printers have been proposed due to 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 roughly divided from the conventional optical mode type using a visible light laser or the like, and has an advantage that it is not restricted by safety light in handling. In addition, printing plates made by these plate making methods are collectively referred to as processless printing plates because they do not require post-exposure development processing that is normally used in conventional optical mode types.

  However, all of the above processless printing plates transfer and impart a grease-sensitive (that is, ink deposition property that ink is deposited during lithographic printing) to the support surface provided with the water retention layer. Since the printing plate is formed, there are 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, the transfer toner image density is insufficient, or white spots occur in the transferred 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 thin background smudge occurs as a result of irregularly transferring a small amount of toner to the non-image area or rubbing the thermal transfer ink ribbon.

  On the other hand, we propose a processless printing plate that provides an oleophilic image area by providing an image-forming layer containing a thermoplastic resin or a heat-meltable substance on a support and performing thermal printing with a thermal head or infrared laser. Has been.

  As the processless printing plate, a printing plate in which an image portion and a non-image portion are formed by a so-called debris process such as a layer removal process such as a conventional ablation method or an on-machine development method is disclosed in Japanese Patent Application Laid-Open No. 2004-237592 (Patent Document 1). ), JP-A-2004-223984 (Patent Document 2), and JP-A-2005-169642 (Patent Document 3).

  However, in the processless printing plate that requires on-press development described in the above-mentioned patent document, there is a problem that debris is mixed into a dampening liquid or ink or a waste paper is generated during on-press development. In addition to these problems, it is more preferable not to require an on-press development process from the viewpoint of working efficiency, and a completely processless printing plate that does not require debris processing has been desired.

  Examples of processless printing plates that do not require debris processing include, for example, JP-A-58-199153 (Patent Document 4), JP-A-59-174395 (Patent Document 5), JP-A-2009-255498 ( Patent Document 6) describes a heat-sensitive lithographic printing plate in which an oleophilic image portion can be obtained by directly drawing heat on an image forming layer with a thermal head or the like without using a thermal transfer ribbon or the like. JP-A-2000-190649 (Patent Document 7) and JP-A-2000-301847 (Patent Document 8) disclose a thermosensitive lithographic plate in which an oleophilic image portion is obtained by heat drawing with an infrared laser or the like. A printed version is listed. These heat-sensitive lithographic printing plates utilize the phase conversion of the thermoplastic resin or hot-melt material contained in the image forming layer. In ordinary lithographic printing, water is added to the oleophilic image area obtained as described above. And the ink are supplied at the same time, the image part (heated part) accepts colored ink, and the other non-image part (unheated part) is hydrophilic and selectively accepts water. Printing is performed by transferring the received ink onto a printing medium such as paper.

  However, in the thermosensitive lithographic printing plate using the above phase conversion, the heated part of the image forming layer is used as an image part and the non-heated part is used as a non-image part. Therefore, the image forming layer itself has an image part and a non-image part. Also serves as. For this reason, even if it is a heat-sensitive lithographic printing plate that uses the same phase conversion, a printing plate that forms an image portion and a non-image portion by so-called debris processing such as layer removal processing such as a conventional ablation method or on-machine development method. Unlike a heat-sensitive lithographic printing plate that removes the non-heated image forming layer by developing with water or a dampening liquid and exposes the hydrophilic layer that becomes the non-image portion, the non-image portion Also contains thermoplastic resins and hot melt materials. 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 the printing durability and stain resistance in a balanced manner. It was.

  On the other hand, paraffin wax and montanic acid ester wax are conventionally known to be used as hot-melt compounds for obtaining lipophilic images, which are described in, for example, Patent Documents 4 to 7 described above. . Further, it is known that zinc stearate is used as a lubricant for maintaining matching with a thermal head, which is disclosed in, for example, JP-A-07-001849 (Patent Document 9) and JP-A-2000-118160. It is described in the gazette (patent document 10) etc.

Japanese Patent Application Laid-Open No. 2004-237592 JP 2004-223984 A JP 2005-169642 A JP 58-199153 A JP 59-174395 A JP 2009-255498 A JP 2000-190649 A Japanese Patent Laid-Open No. 2000-301846 JP 07-001849 A JP 2000-118160 A

  An object of the present invention is to provide a heat-sensitive lithographic printing plate that does not require debris treatment and has excellent printing durability and stain resistance.

  A heat-sensitive lithographic printing plate having at least two image-forming layers containing a water-soluble polymer compound and a thermoplastic resin on a support, wherein the image-forming layer farthest from the support is paraffin wax or montanic ester wax And a heat-sensitive lithographic printing plate containing at least one selected from zinc stearate.

  According to the present invention, a heat-sensitive lithographic printing plate excellent in printing durability and stain resistance can be provided.

  The heat-sensitive lithographic printing plate of the present invention has an image forming layer containing a thermoplastic resin and a water-soluble polymer compound on a support. When the image-forming layer is heated and drawn with a thermal head or infrared laser, the thermoplastic resin buried in the water-soluble polymer compound melts at the part where heat is applied, and is exposed in a form that partly oozes out to the extreme surface of the layer. It becomes hydrophobic and can accept ink at the time of printing. The thermoplastic resin at the site where heat is not applied remains buried in the water-soluble polymer compound, and maintains the hydrophilicity originally possessed by the image forming layer.

  The heat-sensitive lithographic printing plate of the present invention has at least two image forming layers containing a thermoplastic resin and a water-soluble polymer compound. Hereinafter, the image forming layer on the side closer to the support is referred to as the image forming layer (A), and the image forming layer farthest from the other support is referred to as the image forming layer (B). The heat-sensitive lithographic printing plate of the present invention contains at least one selected from paraffin wax, montanic ester wax and zinc stearate in the image forming layer (B). The present invention is described in detail below.

<Paraffin wax>
Paraffin wax belongs to so-called petroleum wax, and is produced by separating and refining from a distilled oil under reduced pressure in petroleum refining. Petroleum wax is roughly classified into three types according to JISK2235: paraffin wax, microcrystalline wax, and petrolatum. Similarly produced microcrystalline wax is mainly composed of branched hydrocarbons (isoparaffins) and cyclic hydrocarbons (cycloparaffins) having a molecular weight range of 500 to 800, carbon number of about 30 to 60, and side chains in a large main chain. In contrast, paraffin wax has a narrow molecular weight range of 300 to 550, a linear hydrocarbon as a main component, and a carbon number in the range of about 20 to 40. Examples of paraffin wax that can be applied to the present invention include Chukyo Yushi Co., Ltd., Hydrin L-703, etc., Nippon Seiwa Co., Ltd. paraffin wax 115, 120, 125, 130, 135, 140, 145, 150, 155, HNP-3, HNP-5, HNP-9, HNP-10, HNP-11, HNP-12, HNP-12, SP-0165, SP- In the name of AQUACER 498, etc. from Big Chemie Japan Co., Ltd. A commercially available product can be mentioned.

<Montanic acid ester wax>
Industrially, montanic acid ester wax is a product obtained by dehydration condensation reaction of montanic acid and dihydric alcohol such as ethylene glycol or butylene glycol, or trihydric alcohol. Mixtures with these are commercially available. In the present invention, a partially saponified product of montanic acid ester wax can be used in the same manner. Examples of montanic acid ester waxes that can be applied to the present invention include Chukyo Oil Co., Ltd., Hydrin J-537, Clariant Japan Co., Ltd., Rico Wax E, etc., Hoechst Co., Ltd. Hoechst Wax E, etc. The thing marketed by the name of can be mentioned.

<Zinc stearate>
Zinc stearate is a metal soap obtained by reacting an aqueous solution of a water-soluble zinc salt with an aqueous sodium stearate solution of a fatty acid. Examples of zinc stearate that can be applied to the present invention include, from Chukyo Yushi Co., Ltd. Hymicron F-930, Hydrin SZ-8-36, SZ-40, Z-7-30, F-115, etc. Examples include SZ-2000, etc., available from Sakai Chemical Industry Co., Ltd., and MXZ50, etc., available from Shin Nippon Rika Co., Ltd.

  The paraffin wax, montanic acid ester wax, and zinc stearate used in the present invention can be used alone or in combination in the image forming layer (B). Further, there is a preferable range for the total content of paraffin wax, montanic acid ester wax and zinc stearate contained in the image forming layer (B), and the amount of the thermoplastic resin contained in the image forming layer (B) It is preferable that it is 15-75 mass%, More preferably, it is 25-58 mass%. Thereby, printing durability and stain resistance can be made compatible at a higher level.

  When deviating from this range, for example, when the total content of paraffin wax, montanic acid ester wax, and zinc stearate contained in the image forming layer (B) is less than 15% by mass, the effect of improving printing durability is achieved. May become insufficient. In addition, when the total content of paraffin wax, montanic acid ester wax, and zinc stearate contained in the image forming layer (B) exceeds 75% by mass, it is difficult to maintain stain resistance, and the printing plate is easily stained. It may become.

  The image forming layer (A) and the image forming layer (B) of the present invention contain a water-soluble polymer compound. Examples of water-soluble polymer compounds include proteins such as gelatin and gelatin derivatives, or cellulose derivatives, natural compounds such as starch, gum arabic, dextran, and pullulan, and the like, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, styrene maleine, and the like. Examples thereof include synthetic polymer compounds such as acid copolymer salts, styrene / acrylic acid copolymer salts, and acrylamide polymers. These water-soluble polymer compounds may be used alone or in combination of two or more. In the image forming layer (A), it is preferable to use gelatin and polyvinyl alcohol in combination, while the image forming layer (B ) Is preferably gelatin from the viewpoint of stain resistance.

  Moreover, when using a water-soluble polymer compound together as mentioned above, there exists an optimal use ratio for each. As an optimal use ratio, it is preferable to use polyvinyl alcohol in the range of 1 to 10% by mass with respect to the solid content of gelatin in the image forming layer (A). The total amount of the water-soluble polymer compound used in the image forming layer (A) and the image forming layer (B) is preferably 0.5 to 25% by mass with respect to the total solid content of the image forming layer.

  The image forming layer (A) and the image forming layer (B) of the present invention contain a thermoplastic resin. The thermoplastic resin is a solid organic polymer compound made of a chain polymer and exhibiting plasticity by heating, and refers to an aqueous dispersion of the organic polymer compound. Representative examples include 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 Aqueous dispersions such as acrylate / acrylate copolymers and low melting point polyamide resins can also be used. These thermoplastic resins can be used alone or in combination of two or more. In view of the affinity with the printing ink vehicle (binder component), the thermoplastic resin is preferably a synthetic rubber latex, and particularly preferably a styrene-butadiene copolymer and a modified product thereof. A preferable blending amount of the thermoplastic resin is preferably 5 to 30% by mass with respect to the total solid content of the image forming layer.

  In order to easily develop 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 the liquid state during the production process, and hydrophobicity is developed even in the non-image area, which may cause printing stains. When the temperature exceeds 150 ° C., the polymer is hardly melted by heat, and it may be difficult to form a strong image with a relatively small output laser or a small thermal printer.

  The content ratio of the thermoplastic resin to the water-soluble polymer compound (mass of thermoplastic resin / total mass of the water-soluble polymer compound) in the image forming layer (A) of the present invention is 0.1 to 50. Preferably, it is 0.5-3. The content ratio of the thermoplastic resin to the water-soluble polymer compound (the mass of the thermoplastic resin / the total mass of the water-soluble polymer compound) in the image forming layer (B) is preferably 0.01 to 10, and Preferably it is 0.1-3. The content ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) is preferably higher than the content ratio in the image forming layer (B). Furthermore, it is more preferable that the difference between the content ratio in the image forming layer (A) and the content ratio in the image forming layer (B) is 0.5 or more. By adjusting to such a range, a heat-sensitive lithographic printing plate excellent in printing durability and stain resistance can be obtained.

  The image forming layer (A) and the image forming layer (B) of the present invention contain at least one selected from the compounds represented by the following general formulas (1) to (4). It is preferable from the point.

  The compound represented by the general formula (1) will be described below.

In the above formula, X ₁ represents —O— or —CO—O—, and R _{1 to} R ₆ each represents a hydrogen atom, an alkyl group, or an aryl group. n represents an integer of 1 to 10, and the substituents R _{1 to} R ₃ and R _{4 to} R ₆ may be bonded to each other to form an aromatic ring.

Among the compounds represented by the general formula (1), a compound in which X ₁ is —O— is preferable, and R ₁ and R ₆ are particularly a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R _{2 to} R _5. A compound in which is a hydrogen atom and n is an integer of 1 to 4 is particularly preferably used.

Examples of the compound represented by the general formula (1) include the following compounds, but the present invention is not limited thereto.
(1) 1- (1-naphthoxy) -2-phenoxyethane (2) 1- (2-naphthoxy) -4-phenoxybutane (3) 1- (2-isopropylphenoxy) -2- (2-naphthoxy) ethane (4) 1- (4-Methylphenoxy) -3- (2-naphthoxy) propane (5) 1- (2-methylphenoxy) -2- (2-naphthoxy) ethane (6) 1- (3-methylphenoxy ) -2- (2-naphthoxy) ethane (7) 1- (2-naphthoxy) -2-phenoxyethane (8) 1- (2-naphthoxy) -6-phenoxyhexane (9) 1-phenoxy-2- ( 2-phenylphenoxy) ethane (10) 1- (2-methylphenoxy) -2- (4-phenylphenoxy) ethane (11) 1,4-diphenoxybutane (12) 1,4-bis (4-methylphenyl) Noxy) butane (13) 1,2-di (3,4-dimethylphenoxy) ethane (14) 1-phenoxy-3- (4-phenylphenoxy) propane (15) 1- (4-tert-butylphenoxy)- 2-phenoxyethane (16) 1,2-diphenoxyethane (17) 1- (4-methylphenoxy) -2-phenoxyethane (18) 1- (2,3-dimethylphenoxy) -2-phenoxyethane (19 ) 1- (3,4-dimethylphenoxy) -2-phenoxyethane (20) 1- (4-ethylphenoxy) -2-phenoxyethane (21) 1- (4-isopropylphenoxy) -2-phenoxyethane (22 ) 1,2-bis (2-methylphenoxy) ethane (23) 1- (2-methylphenoxy) -2- (4-methylphenoxy) ethane (24) -(4-tert-Butylphenoxy) -2- (2-methylphenoxy) ethane (25) 1,2-bis (3-methylphenoxy) ethane (26) 1- (3-methylphenoxy) -2- (4 -Methylphenoxy) ethane (27) 1- (4-ethylphenoxy) -2- (3-methylphenoxy) ethane (28) 1,2-bis (4-methylphenoxy) ethane (29) 1- (2,3 -Dimethylphenoxy) -2- (4-methylphenoxy) ethane (30) 1- (2,5-dimethylphenoxy) -2- (4-methylphenoxy) ethane (31) phenoxyacetic acid-2-naphthyl (32) 2 Naphthoxyacetic acid-4-methylphenyl (33) 2-naphthoxyacetic acid-3-methylphenyl

  Next, the compound represented by the general formula (2) will be described.

In the above formula, R ₇ represents an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group, or an arylsulfonyl group. The naphthalene ring in the formula may further have a substituent, and examples of preferable substituents include an alkyl group, an aryl group, a halogen group, a hydroxy group, an alkoxy group, an aryloxy group, and an alkyloxycarbonyl group. , Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, sulfamoyl group and the like.

Among the substituents represented by R ₇ in the general formula (2), an alkyl group having 4 to 20 carbon atoms, an aryl group having 4 to 24 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, and 7 to 20 carbon atoms. The arylcarbonyl group is more preferable. In the general formula (2), among the substituents that the naphthalene ring may further have, a halogen group, an alkyl group having 1 to 10 carbon atoms, an alkyloxycarbonyl group having 2 to 20 carbon atoms, or a 7 to 20 carbon atom. An aryloxycarbonyl group and a carbamoyl group having 2 to 25 carbon atoms are more preferable.

Examples of the compound represented by the general formula (2) include the following compounds, but the present invention is not limited thereto.
(1) 1-benzyloxynaphthalene (2) 2-benzyloxynaphthalene (3) 2-p-chlorobenzyloxynaphthalene (4) 2-p-isopropylbenzyloxynaphthalene (5) 2-dodecyloxynaphthalene (6) 2 Decanoyloxynaphthalene (7) 2-Myristoyloxynaphthalene (8) 2-p-tert-butylbenzoyloxynaphthalene (9) 2-Benzoyloxynaphthalene (10) 2-Benzyloxy-3-N- (3-dodecyl Oxypropyl) carbamoylnaphthalene (11) 2-benzyloxy-3-N-octylcarbamoylnaphthalene (12) 2-benzyloxy-3-dodecyloxycarbonylnaphthalene (13) 2-benzyloxy-3-p-tert-butylphenoxy Carbonyl naphthalene

  Next, the compound represented by the general formula (3) will be described.

In the above formula, R ₈ and R ₉ represent a hydrogen atom, a halogen group, an alkyl group having 4 or less carbon atoms, or an alkoxy group. X ₂ represents a simple bond or —O—, and n represents an integer of 1 to 4.

Examples of the compound represented by the general formula (3) include the following compounds, but the present invention is not limited thereto.
(1) Bisbenzyl oxalate (2) Bis (p-methylbenzyl) oxalate
(3) Bisoxalate (p-chlorobenzyl)
(4) Bisoxalate (m-methylbenzyl)
(5) Bisoxalate (p-ethylbenzyl)
(6) Bisoxalate (p-methoxybenzyl)
(7) Bisoxalate (2-phenoxyethyl)
(8) Bis oxalate (2-o-chlorophenoxyethyl)
(9) Bis oxalate (2-p-chlorophenoxyethyl)
(10) Bis-oxalate (2-p-ethylphenoxyethyl)
(11) Bisoxalate (2-m-methoxyphenoxyethyl)
(12) Bisoxalate (2-p-methoxyphenoxyethyl)
(13) Bis-oxalate (4-phenoxybutyl)

  Preferred examples of these exemplary compounds include bisbenzyl oxalate, bis (p-methylbenzyl) oxalate, bis (p-chlorobenzyl) oxalate, bis (m-methylbenzyl) oxalate, and bisoxalate. (P-ethylbenzyl) and bis (p-methoxybenzyl) oxalate.

  The compound represented by the general formula (4) will be described below.

In the above formula, R ₁₀ , R ₁₀ ′, R ₁₁ and R ₁₁ ′ represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonyl group or an aryloxy group. .

Examples of the compound represented by the general formula (4) include the following compounds, but the present invention is not limited thereto.
(1) 1,2-bisphenoxymethylbenzene (2) 1,3-bisphenoxymethylbenzene (3) 1,4-bis (2-methylphenoxymethyl) benzene (4) 1,4-bis (3-methyl Phenoxymethyl) benzene (5) 1,3-bis (4-methylphenoxymethyl) benzene (6) 1,3-bis (2,4-dimethylphenoxymethyl) benzene (7) 1,3-bis (2,6 -Dimethylphenoxymethyl) benzene (8) 1,4-bis (2-chlorophenoxymethyl) benzene (9) 1,2-bis (4-chlorophenoxymethyl) benzene (10) 1,3-bis (4-chloro Phenoxymethyl) benzene (11) 1,2-bis (4-octylphenoxymethyl) benzene (12) 1,3-bis (4-octylphenoxymethyl) benzene 13) 1,3-bis (4-isopropylphenyl phenoxymethyl) benzene (14) 1,4-bis (4-isopropylphenyl phenoxymethyl) benzene

  Preferred examples among these exemplary compounds include 1,2-bisphenoxymethylbenzene, 1,4-bis (2-methylphenoxymethyl) benzene, 1,4-bis (3-methylphenoxymethyl) benzene, 1,4-bis (2-chlorophenoxymethyl) benzene may be mentioned.

  Among the compounds represented by the general formulas (1) to (4), the compounds represented by the general formulas (1), (2) and (4) are preferable in that excellent printing durability can be obtained. The compounds represented by (1) and (2) are preferred, and the most preferred compound is the compound represented by the general formula (1).

  The compounds represented by the above general formulas (1) to (4) are solid substances at room temperature, but are preferably used after being subjected to a fine dispersion treatment in order to increase the reactivity with 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 (A) and the image forming layer (B) of the present invention preferably contain a hardening agent (waterproofing agent) depending on the type of the water-soluble polymer compound. As a hardener, a material that imparts water resistance by accelerating the crosslinking of water-soluble polymer compounds such as melamine resin, epoxy resin, polyisocyanate compound, aldehyde compound, silane compound, chromium alum, divinyl sulfone, etc. Although it is possible, divinyl sulfone is particularly preferably used. The compounding amount of the hardener is preferably 0.01 to 30% by mass with respect to the solid content of the water-soluble polymer compound contained in the entire image forming layer, and more preferably 5 to 30% by mass. % Range.

  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 for 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-di (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'-hydro Cyphenyl) ethyl] benzene, 4,4'-dihydroxydiphenyl sulfide, di (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- (phenoxy Phenolic compounds such as (ciethyl) -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, 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-di Tilamino-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) as a thiazine compound , Benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc .: ( 5) As spiro compounds, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3′-dichloro-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 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 agent, 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, squalium 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.

  In addition, the image-forming layer (A) and the image-forming layer (B) of the present invention may contain antiseptics, surfactants, antifoaming agents, leveling agents, pH adjusting agents, other coating aids, and the like as necessary. Can be added.

The image forming layer of the heat-sensitive lithographic printing plate of the present invention has a dry solid content of 0.5 to 30 g / m ² from the viewpoints of printing durability of image areas, water resistance of non-image areas, and mechanical strength. It is preferable. In the present invention, the image forming layer (A) and the image forming layer (B) are coated by applying the image forming layer (A) on the side close to the support, and then the image forming layer (B). There are a method of sequentially applying and stacking layers, a method of simultaneously applying multiple layers by a slide hopper method, and any method may be used. The image forming layer (A) and the image forming layer (B) are preferably adjacent to each other.

  In the heat-sensitive lithographic printing plate of the present invention, an undercoat layer comprising titanium dioxide, a binder resin, and a hardener is preferably provided between the support and the image forming layer. As a result, there is no change in the plate pressure due to contamination due to plate pressure changes during printing, specifically, slight undulations formed on the blanket roller of the printing press, without degrading image quality and printing durability. It is possible to improve the printing stain that occurs and develops at the extreme tip and the bottom edge of the printing paper surface.

  The titanium dioxide contained in the undercoat layer may be either a rutile type or an anatase type, and the production method is not limited to either the sulfuric acid method or the chlorine method. You may use them individually or in mixture. Furthermore, from the viewpoint of dispersion stability and other functionality, it is possible to selectively use those subjected to various surface treatments. As the surface treatment composition, alumina, silica, zinc oxide, zirconia and the like are common. Examples of commercially available titanium dioxide include SR-1, R-650, R-5N, R-7E, R-3L, A-110, and A-190 from Sakai Chemical Industry Co., Ltd. ) From Taipei R-580, R-930, A-100, A-220, CR-58, Titanium Industry Co., Ltd., Kronos KR-310, KR-380, KA-10, KA -20, etc., commercially available under the names of Titanics JR-301, JR-600A, JR-800, JR-701, etc. from Tyca Corporation, and Taipure R-900, R-931, etc. from DuPont. Can be mentioned.

The average particle diameter of titanium dioxide used for the undercoat layer is preferably smaller than the average dry film thickness of the undercoat layer. Titanium dioxide generally exists in the form of secondary particles, tertiary particles, etc., with some primary particles agglomerated. The average particle diameter of the titanium dioxide is, for example, titanium dioxide in a dispersion medium to which a dispersant such as polycarboxylic acid, fatty acid amine, sulfonic acid amide, ε-caprolactone, hydrostearic acid, polyester amine is added. Is dispersed using a media mill such as a ball mill, a bead mill, a sand grinder, a pressure disperser such as a high pressure homogenizer, an ultra high pressure homogenizer, an ultrasonic disperser, and a thin film swirl disperser. It is preferable to adjust appropriately. A preferable average particle size used in the titanium dioxide layer is preferably 0.1 to 1.5 μm, particularly preferably 0.2 to 1.0 μm. The average particle diameter in the present invention can be measured as a number median diameter using a laser scattering particle size distribution meter (for example, LA920 manufactured by Horiba, Ltd.). On the other hand, the dry solid content of the undercoat layer is preferably in the range of 0.5 to 20 g / m ² .

  The content of titanium dioxide used in the undercoat layer can be set in a wide range, but it is preferably used at 200 to 1000% by mass, more preferably based on the solid content of the binder resin contained in the undercoat layer. It is 400-600 mass%. When the content of titanium dioxide is low, the concealing property may be reduced. When used in excess, the stability of the coating liquid may be reduced, or the bulk density may increase due to irregular aggregation. As a result, the surface roughness may increase and the image quality may deteriorate.

  As the binder resin contained in the undercoat layer, for example, gelatin such as lime-processed gelatin, acid-processed gelatin, and enzyme-processed gelatin, and water-soluble polymers such as polysaccharides, polyvinyl alcohol, and polyvinylpyrrolidone can be used. It is preferable to use it.

  As the hardener contained in the undercoat layer, for example, melamine resin, epoxy resin, polyisocyanate compound, aldehyde compound, silane compound, chromium alum, divinyl sulfone and the like can be suitably used. Sulfones are preferred. The blending amount of the hardener is preferably 1 to 30% by mass, more preferably 2 to 15% by mass, based on the solid content of the binder.

  The support used in the heat-sensitive lithographic printing plate of the present invention is preferably a water-resistant support. As such a support, a water-resistant support such as a plastic film, resin-coated paper, and water-resistant paper can be preferably used. Specifically, polyolefin films such as polyethylene and polypropylene, polyethersulfone, polyester, poly (meth) acrylate, polycarbonate, polyamide, and polyvinyl chloride, and plastic-coated paper with a laminated or coated plastic 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. Since the heat-sensitive lithographic printing plate of the present invention has a heat-sensitive image forming layer, the image forming layer can be directly drawn by heat with a thermal head or a heat block to form an image portion. It is preferable to use a thermal head capable of recording a desired image directly from information. It is also possible to form an image portion by irradiating light containing infrared light of, for example, 760 nm to 1200 nm by blending a photothermal conversion substance in the image forming layer.

When plate making is performed using a thermal head, 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 the following description, “%” and “part” are based on mass unless otherwise specified.

Example 1
On one side of a polyethylene resin-coated paper having a thickness of about 180 μm that has been laminated on both sides, slide an undercoat layer coating solution of the following composition, and an image forming layer a-1 and an image forming layer b-1 coating solution. By the hopper coating method, three layers were simultaneously applied from the support side so that the undercoat layer, the image forming layer a-1, and the image forming layer b-1 (uppermost layer) were in this order. At that time, the wet coating weight, the undercoat layer coating solution 15 g / ^{m 2,} the image forming layer a-1 coating liquid 30 g / ^{m 2,} the image forming layer b-1 coating liquid to 10 g / ^{m 2} Set and went.

<Undercoat layer coating solution>
Gelatin (cow bone, alkali treatment, decalcification treatment) 0.8 part Titanium dioxide slurry: 4.0 parts in terms of SR-1 solid content (manufactured by Sakai Chemical Industry Co., Ltd., primary particle size = 0.3 μm)
Pigment dispersant (acrylic acid copolymerized metal salt) solid conversion 0.02 parts Surfactant (ethylhexyl sulfosuccinate) solid conversion 0.0003 parts Hardener (divinyl sulfone) solid conversion 0.1 parts with water The total amount was 15 parts.

<Image forming layer a-1 coating solution>
Gelatin (cow bone, alkali treatment, decalcification treatment) 0.8 part Polyvinyl alcohol: PVA505 0.07 part (manufactured by Kuraray Co., Ltd.)
Carboxylated SBR: Luck Star 7132C solids conversion 1.3 parts (DIC Corporation, Tg = about 60 ° C.)
Developer mixed slurry solid amount conversion 2.9 parts Color developer solid amount conversion 0.2 parts (3-dibutylamino-6-methyl-7-anilinofluorane)
Surfactant (ethylhexyl sulfosuccinate) converted to solid content 0.002 part Hardener (divinyl sulfone) converted to solid content 0.1 part The total amount was 30 parts with water.

<Image forming layer b-1 coating solution>
Gelatin (cow bone, alkali treatment, decalcification treatment) 0.4 part Carboxylated SBR: Lackster 7132C solid amount conversion 0.3 part (DIC Co., Ltd., Tg = about 60 ° C.)
0.2 parts of color former solid conversion (3-dibutylamino-6-methyl-7-anilinofluorane)
Paraffin wax: Hydrin L-703 solid conversion 0.1 part Surfactant (ethylhexyl sulfosuccinate) solid conversion 0.001 part Hardener (divinyl sulfone) solid conversion 0.05 part 10 parts total with water It was.

  For the preparation of the titanium dioxide slurry used in the undercoat layer coating solution, an acrylic acid copolymerized metal salt was used as a pigment dispersant. The production method can be produced by gradually adding titanium dioxide into water to which a pigment dispersant has been added with constant stirring, and performing high-speed fine dispersion treatment for 30 minutes using a homomixer. The slurry used was prepared just before preparing the coating solution.

Further, the developer mixed slurry used in the image forming layer a-1 coating solution was prepared and manufactured in advance with the following constituent chemicals.
<Constituent chemicals of developer mixed slurry>
Material a: KS-232
(Sanko Co., Ltd., sensitizer, 1,2-bis (3-methylphenoxy) ethane)
Material b: D-8
(Nippon Soda Co., Ltd., developer, 4-hydroxy-4'-isopropoxydiphenyl sulfone)
Material c: Polymeron 1318
(Arakawa Chemical Industries, Ltd., dispersant, 15% aqueous solution of anionic styrenic resin)

  After mixing 1 part of each of material a and material b in water with 0.7 parts of the above material c added under constant stirring, the particle size was reduced to 0 using zirconia beads in a small dyno mill (bead mill). A fine dispersion treatment was performed to .68 μm to obtain a developer mixed slurry. In addition, it prepared so that solid content concentration in the sum total of the material a, the material b, and the material c might be 35%.

  For other chemicals, no special adjustment was made except for water splitting, except that hydrophilic polymers such as gelatin and polyvinyl alcohol were heated and dissolved in water. However, with respect to the developer mixed slurry, care was taken from the stage of preparation and with respect to the color former, so that the temperature did not exceed 45 ° C. throughout the handling.

  After three layers were simultaneously applied at the moisture application amount, the coating film was immediately gelled with cold air of 1 to 3 ° C., and then dried with hot air set at 30 ° C. After drying, a thermosensitive lithographic printing plate of Example 1 was obtained by heating for 7 days using a constant temperature and humidity chamber 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). And an electric capacity of 330 W) to produce a printing plate. Using this printing plate, printability was evaluated by the following method.

<Evaluation of printing durability>
The printing machine uses an offset printing machine HAMADA H234C manufactured by Hamada Printing Machine Co., Ltd., New Champion F Gloss ink H manufactured by DIC Corporation for printing ink, and SLM- manufactured by Mitsubishi Paper Industries Co., Ltd. for dampening liquid. Printing was performed using OD as a 10% diluent, and SLM-OD30 manufactured by Mitsubishi Paper Industries Co., Ltd. as a 25% diluent. The printing durability was evaluated by comparing the printing paper surface at the start and the printing paper surface at the time of printing 5,000 sheets, observing the attenuation rate of 15% halftone dots and 50% halftone dots, and evaluating the following criteria: Was used to determine. The results are shown in Table 1.
◎: Almost no change in both 15% and 50% halftone dots ○: Almost no change in the 50% halftone dots, but slight attenuation can be confirmed in the 15% halftone dots △: Almost no change in the 50% halftone dots Although there is no, attenuation can be confirmed at the 15% halftone dot portion. X: Attenuation can be confirmed at both the 15% and 50% halftone dot portions.

<Evaluation of stain resistance>
The printing machine uses Ryobi Magics Co., Ltd. offset printing machine Ryobi 3200CD, the printing ink is DIC Co., Ltd.'s New Champion F gloss ink S, and the dampening solution is SLM-OD made by Mitsubishi Paper Industries Co., Ltd. Was used as a 2% diluted solution, and the same moisturizing solution was used as an etching solution for printing. As evaluation of stain resistance, the number of sheets on which non-image areas of the printed matter were stained was determined using the following evaluation criteria. The results are shown in Table 1.
◎: More than 3,000 sheets ○: 1,000 to less than 3,000 sheets △: Less than 500 to 1,000 sheets ×: Less than 500 sheets

(Example 2)
In the same manner as in Example 1 except that montanic acid ester wax (manufactured by Chukyo Yushi Co., Ltd., Hydrin J-537) was used instead of the paraffin wax used in the image forming layer b-1 coating liquid of Example 1, A heat-sensitive lithographic printing plate of Example 2 was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 3)
In the same manner as in Example 1 except that zinc stearate (manufactured by Chukyo Yushi Co., Ltd., High Micron F-930) was used instead of the paraffin wax used in the image forming layer b-1 coating liquid of Example 1, A heat-sensitive lithographic printing plate of Example 3 was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

Example 4
Thermal lithographic printing of Example 4 in the same manner as in Example 1 except that the amount of paraffin wax used in the image forming layer b-1 coating liquid of Example 1 was changed from 0.1 part to 0.05 part. Got a version. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 5)
Thermal lithographic printing of Example 5 in the same manner as in Example 1 except that the amount of paraffin wax used in the image forming layer b-1 coating liquid of Example 1 was changed from 0.1 part to 0.15 part. Got a version. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 6)
Thermal lithographic printing of Example 6 in the same manner as in Example 1 except that the amount of paraffin wax used in the coating liquid for image forming layer b-1 in Example 1 was changed from 0.1 part to 0.2 part. Got a version. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 7)
The heat-sensitive type of Example 7 is the same as Example 2 except that the amount of the montanic ester wax used in the image forming layer b-1 coating liquid of Example 2 is changed from 0.1 part to 0.05 part. A lithographic printing plate was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 8)
The heat sensitive type of Example 8 is the same as Example 2 except that the amount of the montanic ester wax used in the image forming layer b-1 coating liquid of Example 2 is changed from 0.1 part to 0.15 part. A lithographic printing plate was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

Example 9
The heat-sensitive type of Example 9 is the same as Example 2 except that the amount of the montanic ester wax used in the image forming layer b-1 coating liquid of Example 2 is changed from 0.1 part to 0.2 part. A lithographic printing plate was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 10)
Heat sensitive planographic plate of Example 10 in the same manner as Example 3 except that the amount of zinc stearate used in the image forming layer b-1 coating solution of Example 3 was changed from 0.1 part to 0.05 part. A printed version was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 11)
Heat-sensitive lithographic plate of Example 11 in the same manner as in Example 3 except that the amount of zinc stearate used in the image-forming layer b-1 coating solution of Example 3 was changed from 0.1 part to 0.15 part. A printed version was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 12)
Thermal lithographic plate of Example 12 in the same manner as in Example 3 except that the amount of zinc stearate used in the image forming layer b-1 coating solution of Example 3 was changed from 0.1 part to 0.2 part. A printed version was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Example 13)
0.05 part of paraffin wax (hydrin L-703) and 0.05 part of montanic ester wax (hydrin) instead of 0.1 part of paraffin wax used in the image forming layer b-1 coating liquid of Example 1 A heat-sensitive lithographic printing plate of Example 13 was obtained in the same manner as in Example 1 except that J-537) was used in combination. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Comparative Example 1)
A heat-sensitive lithographic printing plate of Comparative Example 1 was obtained in the same manner as in Example 1 except that the paraffin wax used in the image forming layer b-1 coating solution of Example 1 was omitted. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Comparative Example 2)
In the same manner as in Example 1, except that the wax was changed to polypropylene wax (manufactured by Big Chemie Japan Co., Ltd., AQUACER 593) instead of the paraffin wax used for the image forming layer b-1 coating liquid of Example 1, Comparative Example 2 A heat-sensitive lithographic printing plate was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Comparative Example 3)
In the same manner as in Example 1, except that the wax was changed to polyethylene wax (manufactured by Big Chemie Japan Co., Ltd., AQUAMAT 263) instead of the paraffin wax used in the image forming layer b-1 coating liquid of Example 1, Comparative Example 3 A heat-sensitive lithographic printing plate was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Comparative Example 4)
In the same manner as in Example 1 except that stearic acid amide (manufactured by Chukyo Yushi Co., Ltd., High Micron L-271) was used instead of the paraffin wax used in the image forming layer b-1 coating liquid of Example 1, A heat-sensitive lithographic printing plate of Comparative Example 4 was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Comparative Example 5)
Comparative Example as in Example 1, except that carnauba wax (manufactured by Chukyo Yushi Co., Ltd., Cellozol K-375) was used instead of the paraffin wax used in the image forming layer b-1 coating liquid of Example 1. No. 5 thermal lithographic printing plate was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Comparative Example 6)
Example 1 is the same as Example 1 except that 0.45 parts of paraffin wax is added to the image forming layer a-1 coating solution of Example 1 except for the paraffin wax used in the image forming layer b-1 coating solution of Example 1. Similarly, a heat-sensitive lithographic printing plate of Comparative Example 6 was obtained. Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

(Comparative Example 7)
An undercoat layer coating solution having the above composition and a single image forming layer c-1 coating solution are 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. Two layers were simultaneously applied from the support side in the order of the undercoat layer and the image forming layer c-1. At that time, the wet coating weight, the undercoat layer coating solution 15 g / ^{m 2,} the image forming layer c-1 coating liquid was performed by setting the 40 g / ^{m 2.} Thus, a heat-sensitive lithographic printing plate of Comparative Example 7 was obtained.

<Image forming layer c-1 coating solution>
Gelatin (cow bone, alkali treatment, decalcification treatment) 1.1 parts Polyvinyl alcohol: 0.1 part of PVA505 (manufactured by Kuraray Co., Ltd.)
Carboxylated SBR: Luck Star 7132C solids conversion 1.4 parts (DIC Corporation, Tg = about 60 ° C.)
Developer mixed slurry solid amount conversion 2.0 parts Color former solid amount conversion 0.2 parts (3-dibutylamino-6-methyl-7-anilinofluorane)
Paraffin wax: Hydrin L-703 solid equivalent 0.46 parts Surfactant (ethylhexyl sulfosuccinate) solid equivalent 0.003 parts Hardener (divinylsulfone) solid equivalent 0.1 parts 40 parts total with water It was.

  Using the obtained heat-sensitive lithographic printing plate, an image was output in the same manner as in Example 1 to produce a printing plate and evaluated. The results are shown in Table 1.

  As can be seen from the results shown in Table 1, it can be seen that the heat-sensitive lithographic printing plate of the present invention is a heat-sensitive lithographic printing plate having excellent printing durability while maintaining sufficiently high stain resistance.

Claims (1)

  A heat-sensitive lithographic printing plate having at least two image-forming layers containing a water-soluble polymer compound and a thermoplastic resin on a support, wherein the image-forming layer farthest from the support is paraffin wax or montanic ester wax And a heat-sensitive lithographic printing plate comprising at least one selected from zinc stearate.