JP2010167593A - Method for printing with heat-sensitive lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for printing with a heat-sensitive lithographic printing plate which is almost free from plate smudge without image decolorization which occurs when a printing matrix treatment is applied to an imaging layer, and also, without impeding the smooth spread of ink during starting the printing of an image part. <P>SOLUTION: The heat-sensitive lithographic printing plate with the imaging layer containing at least, a thermoplastic resin, a water-soluble polymer compound, a developer and a coupler, formed on a water-resistant support, is heated or irradiated with light to the image pattern. Consequently, an image part is formed, and before the start of printing, the printing matrix treatment containing the following chemical compounds (i) and (ii) is applied to the printing matrix and a printing is made; (i) inorganic fine particle and (ii) a polyol compound with a boiling point of not less than 180°C and the number of carbon atoms of not more than 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a processless printing plate, and relates to a printing method for a heat-sensitive lithographic printing plate that does not require a development treatment with an alkali developer.

  With the recent development of computers and peripheral devices, a planographic printing plate making method using various digital printers has been proposed. As a plate making method of such a lithographic printing plate, for example, plate making with a dry electrophotographic laser printer as described in JP-A-6-138719 and JP-A-6-250424, JP-A-9-58144 is disclosed. Making a plate using an on-demand ink jet printer using a hot-melt ink as described in Japanese Patent Publication No. JP-A 63-166590, or making a plate using a thermal printer using a thermal transfer ink ribbon described in Japanese Patent Laid-Open No. 63-166590 Things are known.

  The plate making method using the above various digital printers is different from the conventionally known plate making method of a lithographic printing plate having a silver halide emulsion layer, or the plate making method of a lithographic printing plate in which a photosensitive resin is applied to a water retaining surface. There is an advantage that a lithographic printing plate can be easily and easily made from the viewpoint that there is no restriction of upper safety light and that no development treatment with an alkaline developer is required after image recording. The printing plates used for these plate making methods are collectively referred to as processless printing plates.

  However, all of the above processless printing plates form a printing plate by transferring a grease-sensitive (that is, lithographic printing ink inking property) recorded image to the surface of a support provided with a water retention layer. Therefore, 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, there are problems such as insufficient transfer toner image density and whiteout transfer image.
2) The transfer image is not sufficiently fixed, and the printing durability is insufficient. In particular, there are problems such as omission of part of small point characters and small dots of a halftone dot image.
3) There is a problem that a small amount of toner is irregularly transferred to the non-image area or the thermal transfer ink ribbon is rubbed, resulting in generation of thin print stains as a whole.

  In order to solve the above problem, there has been proposed a heat-sensitive lithographic printing plate capable of directly forming an image with a thermal head or the like without using a thermal transfer ribbon or the like, for example, Japanese Patent Application Laid-Open No. 58-199153 (Patent Document 1) or Japanese Patent Application Laid-Open No. 59. Direct heat-sensitive which can form an image part by bringing a water-soluble polymer compound and a heat-meltable substance described in JP-A-174395 (Patent Document 2) and the like into an image forming layer, and contacting a thermal head or the like. An image of a photothermal conversion substance and a heat-meltable particle or thermoplastic polymer described in a type planographic printing plate, for example, JP-A-2000-190649 (Patent Document 3), JP-A-2000-301847 (Patent Document 4), etc. Heat-sensitive lithographic printing plates and the like that are contained in the forming layer and can form an image portion by irradiation with an infrared laser are known. In forming the non-image portion of these heat-sensitive lithographic printing plates, there are a type in which the non-image portion is removed with an aqueous liquid such as dampening water and a type in which the non-image portion is not removed.

  However, such heat-sensitive lithographic printing plates generally have a difference in hydrophilicity / lipophilicity between the non-image area and the image area, so that it is difficult to obtain a clear printed image and the printing durability is insufficient. Or has a problem of being easily soiled (stained by printing).

  As a heat-sensitive lithographic printing plate from which a clear image having a high image density can be obtained, for example, inorganic pigments, thermoplastic resins and hot-melt materials as described in JP-A-63-64747 (Patent Document 5) are used. A heat-sensitive lithographic printing plate having an image forming layer is known. Further, the thermosensitive lithographic printing plate described in Patent Document 3 and Patent Document 4 described above contains heat-melting fine particles that exhibit lipophilicity in order to improve the balance between the lipophilicity of the image area and the hydrophilicity of the non-image area. A method of coating with a substance having a specific thermal conductivity and a device for hydrophobizing hydrophilic groups of a hydrophilic polymer using a chelate reaction by heat are disclosed. However, in both cases, it is difficult to control the reaction, and the difference in hydrophilicity / lipophilicity between the non-image area and the image area is not sufficient, so that it is difficult to obtain a clear printed image, printing durability is insufficient, There was a problem that it was easy to do.

  As a method for imparting the hydrophilicity of the non-image portion of the planographic printing plate to the problem of printing stains, a plate surface treatment solution disclosed in JP-A-5-289341, a plate surface treatment solution disclosed in JP-A-7-56349, and JP-A-9 No. 2777736, a fixing agent disclosed in Japanese Patent Publication No. 45-29001, a neutralizing liquid disclosed in Japanese Patent Publication No. 61-28987, and a plate surface treatment liquid containing inorganic fine particles such as a desensitizing liquid. It has been. However, when such a plate surface treatment liquid is applied to the plate surface, once the plate surface treatment liquid is applied and dried once, the inorganic fine particles adhere as a hydrophilic film on the image area, and the oil sensitivity of the image area There is a problem that gets worse. In particular, when applying the plate surface treatment liquid to the plate surface using an etching converter (plate surface processing apparatus), the plate surface treatment liquid is squeezed using two rolls, so it is easy to dry and the plate surface is dried before being applied to the printing press. However, there is a problem that the oil sensitivity of the image portion is likely to deteriorate.

  In order to solve this problem, it is generally considered that drying is prevented by containing a wetting agent. For example, Japanese Patent Publication No. 56-41992 (Patent Document 6) discloses a medium containing colloidal fine particles and a hygroscopic polyol. Japanese liquor is described. However, the wetting agent used in Patent Document 6 includes those that erase the color of the color former for enhancing the visibility of the image in the thermal lithographic printing plate. If the color of the color former is erased, the color of the image disappears on the plate surface and cannot be identified.

JP 58-199153 A JP 59-174395 A JP 2000-190649 A Japanese Patent Laid-Open No. 2000-301846 JP-A 63-64747 Japanese Examined Patent Publication No. 56-41992

  An object of the present invention is to improve printing stains without causing the image to be decolored when a plate surface treatment liquid is applied to the image forming layer, and without hindering ink loading when the image portion is printed. Another object of the present invention is to provide a method for printing a heat-sensitive lithographic printing plate.

The above object of the present invention is to heat or light-irradiate a lithographic printing plate having an image forming layer containing at least a thermoplastic resin, a water-soluble polymer compound, a developer and a color former on a water-resistant support. However, in a printing method of a heat-sensitive lithographic printing plate in which an image portion is formed by photothermal conversion, printing is performed after applying a plate surface treatment liquid containing the following compounds (i) and (ii) before starting printing. It can be achieved by a printing method of a heat-sensitive lithographic printing plate.
(I) Inorganic fine particles (ii) A polyol compound having a boiling point of 180 ° C. or more and 4 or less carbon atoms

  According to the present invention, when the plate surface treatment liquid is applied to the image forming layer, the image is not decolored, and the printing stain is improved without hindering ink loading when the image portion is printed. It is possible to provide a method for printing a heat-sensitive lithographic printing plate.

  The heat-sensitive lithographic printing plate according to the present invention has an image forming layer containing at least a thermoplastic resin, a water-soluble polymer compound, a developer, and a color former on a water-resistant support. The image of such a heat-sensitive lithographic printing plate maintains hydrophilicity when heat is not applied (non-image area), but when heat is applied, the heat-melting fine particles contained in the portion are mutually soluble and water-soluble. The polymer compound is also melted, and the heated portion is converted into hydrophobicity as a whole. Accordingly, since the portion to which heat is applied is converted into hydrophobicity, it becomes possible to receive ink at the time of printing. However, even in non-image areas where heat is not applied, hydrophobic heat-melting fine particles are present, and the hydrophilicity of the entire layer is poor. For this reason, it is possible to suppress the occurrence of printing stains by previously including a plate surface treatment liquid containing inorganic fine particles having high water retention in the hydrophilic layer before the start of printing. However, after pre-applying a plate surface treatment liquid containing inorganic fine particles, once dried, a hydrophilic film is formed on the image area, and the oil sensitivity (ink-carrying property) of the image area is inhibited and printing is adversely affected. There is a risk of inviting. Therefore, it is necessary to contain a wetting agent so that the inorganic fine particles are not dried. However, a commonly used wetting agent erases the color of the color former contained in the image forming layer. Therefore, as a result of intensive studies, the present inventors have determined that a non-image area can be obtained by using a plate surface treatment liquid containing inorganic fine particles and a polyol compound having a boiling point of 180 ° C. or more and having 4 or less carbon atoms without impairing the oil sensitivity of the image area. The present inventors have found a printing method that is hydrophilic and does not erase the color of the color former of the heat-sensitive lithographic printing plate.

  The plate surface treatment liquid used in the present invention will be described. The inorganic fine particles contained in the plate surface treatment liquid used in the present invention preferably have a particle diameter of 0.1 μm or less, which is easily dispersed and stable in water. Examples of such inorganic fine particles include fine particles of silica, alumina, zirconia, titania, and the like, but silica fine particles and alumina fine particles are particularly preferable in preventing printing stains. Among them, colloidal silica is most preferable. For example, from Nissan Chemical Industries, Snowtex XS, Snowtex XL, Snowtex YL, Snowtex ZL, Snowtex MP-2040, Snowtex C, etc. It is commercially available as a dispersion of various inorganic fine particles from Nissan Chemical Industries, Ltd. under the trade names such as alumina sol 100 and alumina sol 520.

  When the concentration of the inorganic fine particles is high, if the plate surface treatment liquid is applied and then dried once, the oil sensitivity of the image area is inhibited, and the printing paper is damaged. Since the application effect is difficult to obtain, printing stains in the non-image area and clogging in the dot shadow area occur, resulting in an increase in waste paper. Therefore, the plate surface treatment liquid used in the present invention preferably contains 0.1 to 10% by mass of inorganic fine particles (as oxides). More preferably, it is the range of 0.1-3 mass%.

  Examples of the polyol compound having a boiling point of 180 ° C. or higher and 4 or less carbon atoms contained in the plate surface treatment liquid used in the present invention include glycerin (boiling point 290 ° C.), ethylene glycol (boiling point 197.85 ° C.), trimethylene glycol (boiling point). 214 ° C.), propylene glycol (188 ° C.), 1,3-butylene glycol (boiling point 207.5 ° C.) and the like. When the boiling point is less than 180 ° C., when the plate surface treatment liquid is applied and then dried once, the oil sensitivity of the image area is hindered, and the amount of paper loss at the time of printing increases. Further, when the number of carbon atoms is 5 or more, the image is decolored.

  When the content of the polyol compound having a boiling point of 180 ° C. or more and having 4 or less carbon atoms is too high, it is difficult to obtain the effect of imparting hydrophilicity. As a result, waste paper may increase. On the other hand, if the concentration is low, when the plate surface treatment liquid is applied and then dried once, the oil sensitivity of the image area may be hindered, resulting in a large amount of paper loss during printing. Accordingly, the plate surface treatment liquid used in the present invention preferably contains a polyol compound having a boiling point of 1 to 30% by mass and having a boiling point of 180 ° C. or more and 4 or less carbon atoms. More preferably, it is the range of 3-15 mass%.

  The plate surface treatment liquid used in the present invention contains water as a main component and the above-described inorganic fine particles and a polyol compound having a boiling point of 180 ° C. or more and a carbon number of 4 or less. A surfactant for adjusting the tension, a hydrophilic composition that promotes desensitization of the non-image area, a pH buffer, a preservative, a colorant, an antiseptic, a rust inhibitor, and the like may be included. Specific examples of these inclusions include anionic, cationic, betaine, or nonionic surfactants as surfactants, and gum arabic, carboxymethylcellulose, sodium alginate, polyvinylpyrrolidone, polyvinylimidazole, polyvinyl as hydrophilic compositions. Examples thereof include organic substances such as methyl ether and maleic anhydride copolymer, carboxymethyl starch, ammonium alginate, alginate oxydide cellulose, and methyl cellulose. Examples of the pH buffering agent include sulfates such as sodium sulfate and ammonium sulfate, phosphoric acid, nitric acid, nitrous acid, tannic acid, and salts thereof. Other complex components include weak organic acids (citric acid, succinic acid, tartaric acid, adipic acid, ascorbic acid, propionic acid, etc.), polyacrylic acid, ammonium dichromate, chromium alum, propylene glycol alginate, amino Examples thereof include polycarboxylic acid salts (such as sodium ethylenediaminetetraacetate), polymers as described in JP-A No. 64-38292, chelating agents such as iminodiacetic acid and ethylenediaminetetraacetic acid.

  In the printing method of the present invention, the above-mentioned plate surface treatment liquid is applied to the plate surface before starting printing, and as this method, a method of impregnating the surface treatment solution with absorbent cotton or the like and performing hand etching, a certain amount of plate surface treatment A method of applying the liquid with a bar coater, a method of using an etching converter that immerses the excess plate surface treatment liquid with a roll pair by immersing it in a liquid bath storing the plate surface treatment liquid, and the like can be applied. The timing for applying the plate surface treatment liquid is preferably from when the printing plate is mounted (printed) on the printing machine until printing is started, or immediately before printing.

  Next, the heat-sensitive lithographic printing plate according to the present invention will be described in detail. As a method for forming an image portion of such a heat-sensitive lithographic printing plate, a direct heat-sensitive type in which the image forming layer is heated in an image-like manner by directly contacting means such as a thermal head, or a photothermal conversion agent is further added to the image forming layer. And a photothermal conversion type in which heating is performed by exposing in an image-like manner. In addition, as a method for forming the non-image area, a water retention layer containing inorganic fine particles typified by colloidal silica and the image forming layer are provided in this order on a water-resistant support. Wet development that removes the unheated part (non-image part) of the image forming layer by developing with a developer containing substantially no alkali component after the image is formed by the forming method, or by developing on a printing press. Examples thereof include a dry type that uses an unheated portion (non-image portion) after image formation without providing a water retention layer as a portion that imparts water retention as it is. Among them, the direct heat-sensitive image forming type is preferable in that an image portion having high energy transmission efficiency and excellent oleophilicity and printing durability is obtained, and is a dry type in that waste liquid is not generated in development processing. It is preferable.

  The heat-sensitive lithographic printing plate according to the present invention has an image forming layer containing at least a thermoplastic resin, a water-soluble polymer compound, a developer and a color former on a water-resistant support. Of course, this layer alone may be a single layer, and the adhesiveness with a heat-sensitive color developing layer for obtaining visibility as a lower layer, a layer for improving hydrophilicity including hydrophilic inorganic fine particles, and a support described later. You may coat the layer for improving, etc.

  As the water-soluble polymer compound that the image forming layer of the heat-sensitive lithographic printing plate according to the present invention has, it can be effectively used as long as it retains water during printing and has a binder element that can exist as a layer. it can. Specific examples include the following.

  Natural products include starch and derivatives thereof, seaweed mannan, agar, and algae such as sodium alginate, mannan, pectin, tragacanth gum, karaya gum, xanthine gum, guarbin gum, locust bin gum, gum arabic, etc. Homopolysaccharides such as glucan, xanthan gum and levan, microbial mucilage such as heteropolysaccharide such as succinoglucan, pullulan, curdlan and xanthan gum, glue, gelatin, casein and collagen and other proteins, chitin and derivatives thereof, etc. Is mentioned.

  Semi-natural products (semi-synthetic products) include celluloses such as hydroxyethyl cellulose, methyl cellulose and carboxymethyl cellulose, modified gums such as carboxymethyl guar gum, and baked starches such as dextrin, oxidized starches, and esterified starches. Modified starches and the like.

  Synthetic products include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, partially acetalized polyvinyl alcohol, modified polyvinyl alcohols such as allyl-modified polyvinyl alcohol, polyvinyl methyl ether, polyvinyl ethyl ether, Modified polyvinyl ethers such as polyvinyl isobutyl ether, polyacrylic acid salts, polyacrylic acid ester partial saponified products, polymethacrylic acid salts, polyacrylic acid derivatives such as polyacrylic acid and polymethacrylic acid derivatives, polyethylene glycol, polyethylene oxide, Polyvinylpyrrolidone, vinylpyrrolidone / vinyl acetate copolymer, carboxyvinyl polymer, styrene / maleic acid copolymer , Styrene / crotonic acid copolymer, include water-soluble polymers exemplified in P1~P24 described in JP 2006-247937.

  These water-soluble polymer compounds may be used alone or in combination of two or more. Particularly, gelatin and polyvinyl alcohol rich in film formation and modified products thereof are preferably selected for maintaining the hydrophilicity of the non-image area. The blending amount is preferably 0.5 to 30% by mass, more preferably 3 to 25% by mass with respect to the total solid content of the image forming layer. If the amount is less than 0.5% by mass, the hydrophilicity of the non-image area may not be obtained, and printing may be easily smudged. If the amount exceeds 30% by mass, the thermal sensitivity is lowered, and the oil sensitivity of the image part is lowered. In some cases, sufficient printing durability cannot be obtained. Among these hydrophilic resins, gelatin, modified or unmodified polyvinyl alcohol, and cellulose derivatives can be advantageously used. In particular, the use of gelatin is preferable because of its excellent balance between water retention and strength.

  As the gelatin used for the image forming layer according to the present invention, any gelatin made from animal collagen can be used, but gelatin made from collagen obtained from pig skin, cow skin, and cow bone is preferred. The type of gelatin is not particularly limited, but in addition to lime-processed gelatin and acid-processed gelatin, JP-B-38-4854, JP-B-39-5514, JP-B-40-12237, and JP-B-42-26345. No. 2,525,753, U.S. Pat.No. 2,594,293, U.S. Pat.No. 2,614,928, U.S. Pat.No. 2,763,639, U.S. Pat.No. 3,118,766. No. 3, U.S. Pat. No. 3,132,945, U.S. Pat. No. 3,186,846, U.S. Pat. No. 3,312,553, British Patent No. 1,033,189, etc. A derivative etc. are mentioned, These can be used 1 type or in combination of 2 or more types.

  In order to improve the water resistance and mechanical strength of the non-image area, the image forming layer preferably contains a curing agent (waterproofing agent) according to the type of the water-soluble polymer compound. As the curing agent, melamine resin, epoxy resin, polyisocyanate compound, aldehyde compound, silane compound, chromium alum, divinyl sulfone, and the like that can impart water resistance by promoting the crosslinking of the resin can be used. In some cases, for example, inorganic compounds such as chromium alum, formalins, glyoxal, malealdehyde, aldehydes such as glutaraldehyde, N-methylol compounds such as urea and ethyleneurea, mucochloric acid, 2,3-dihydroxy-1, Aldehyde-related compounds such as 4-dioxane, 2,4-dichloro-6-hydroxy-s-triazine salts and compounds having active halogen such as 2,4-dihydroxy-6-chloro-s-triazine salts, divinyl Sulfone, divinyl ketone and N, N, N-tria One or two of various compounds such as liloyl hexahydrotriazine, compounds having two or more active three-membered ethyleneimino groups and epoxy groups in the molecule, and dialdehyde starch as a polymer hardener It is preferable to use more than one species. In the case of polyvinyl alcohol, it is preferable to use aldehydes such as formalin, glyoxal, malealdehyde, and glutaraldehyde. Particularly preferably, in the case of gelatin, divinyl sulfone is glyoxal in the case of polyvinyl alcohol.

  The blending amount of the curing agent is preferably 1 to 30% by mass, more preferably 2 to 15% by mass, based on the solid content of the water-soluble polymer compound, from the viewpoint of avoiding fluctuations in characteristics over time when stored. It is preferable that

  The thermoplastic resin contained in the image forming layer according to the present invention will be described. The thermoplastic resin according to the present invention is a solid organic polymer compound made of a chain polymer and exhibiting plasticity upon 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, acrylic Aqueous dispersions such as acid ester / acrylic acid ester 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 in particular, a styrene-butadiene copolymer and a modified product thereof are desirable. A preferable blending amount is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass with respect to the total solid content of the image forming layer. Moreover, in order to make the melting and fusing effect due to heat easy to develop, 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 oleophilicity is exhibited also in the non-image area, which may cause printing background 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 thermoplastic resin is finely divided and is solid or dispersed in water. Examples include polymer latex that can be dispersed in an aqueous solvent. Examples of the dispersed state include those in which fine particles of a water-insoluble hydrophobic polymer are dispersed, or polymer molecules that form molecular states or micelles. In any case, it can be suitably used. These average particle diameters are preferably 1 to 50000 nm, more preferably 5 to 1000 nm. The particle size distribution of the polymer latex is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution. By heating, they are melted or fused together to change from the fine particle form and integrate.

These thermoplastic resins can be used as a mixture of two or more as required, or may be a plurality of layers. A resin that self-crosslinks when heated is particularly preferred. The amount of the thermoplastic resin contained in the image forming layer of the heat-sensitive lithographic printing plate according to the present invention is optimized depending on the balance with the hydrophilic resin used and the desired sensitivity. It may be in the range of m ² , preferably 0.1 to 5 g / m ² . More preferably from 0.5 to 2 g / ^{m 2.}

  The balance between the water-soluble polymer compound and the thermoplastic resin in the image forming layer according to the present invention may be in the range of 1:10 to 2: 1 by mass ratio. In detail, it is preferable to optimize the balance between ink transportability and water retention in a printing test depending on the material used.

  The color former (electron-donating dye precursor) contained in the image forming layer according to the present invention will be described. The color former is used for ensuring the visibility of the image portion of the heat-sensitive lithographic printing plate. As a specific example, (a) a triarylmethane compound, 3,3′-bis (p-dimethylamino) is used. Phenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3′-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethyl) Indol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole- 3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylin) -3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindole-3) -Yl) -5-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide, etc .: (b) 4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl leucooramine, N-2,4,5-trichlorophenyl leucooramine and the like: (c) Rhodamine B-anilinolactam as a xanthene compound , Rhodamine Bp-nitroanilinolactam, rhodamine Bp-chloroanilinolactam, 3-diethylamino- -Dibenzylaminofluorane, 3-diethylamino-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-ani Linofluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane Etc .: (d) as thiazine compounds, benzoylleucomethylene blue, p-nitrate Lobenzoyl leucomethylene blue and the like: (e) 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. Two or more of these may be used in combination.

The amount of the color former contained in the image forming layer according to the present invention is optimized depending on the balance with the water-soluble polymer compound used and the desired sensitivity, but in the range of 0.01 to 10 g / m ² . It may be sufficient, Preferably it is 0.1-1 g / m < ² >.

  The image forming layer according to the present invention contains a color developer such as a phenol derivative or an aromatic carboxylic acid derivative in order to develop a color developer in a portion to which heat is applied. 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 amount of the developer contained in the image forming layer of the heat-sensitive lithographic printing plate according to the present invention is optimized depending on the balance with the water-soluble polymer compound used and the desired sensitivity. I may be in the range of 10 g / ^{m 2,} preferably from 0.5 to 5 g / ^{m 2.}

  The image forming layer according to the present invention may further contain a photothermal conversion substance in addition to the thermoplastic resin, the water-soluble polymer compound, the developer and the color former. By including a photothermal conversion substance, writing with active light such as an infrared laser as well as a thermal head is possible. As 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 using a semiconductor laser that emits near infrared light as the light source, Near-infrared light absorbers having an absorption band are preferable, for example, organic compounds such as carbon black, cyanine dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, And metal compounds such as 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 according to the present invention preferably contains at least one selected from compounds represented by the following general formulas (1) to (4). By containing these compounds, when the surface of the image forming layer is applied with heat, the melting start temperature of the thermoplastic resin is lowered, and an image part having excellent oleophilicity on the plate surface is obtained with less energy, and a clear printed image is obtained. Sufficient printing durability can be obtained. Further, when the image forming layer is the outermost layer, sticking can be improved at the same time.

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

In the above formula, X ¹¹ represents —O— or —CO—O—, and R ^{11 to} R ¹⁶ each represents a hydrogen atom, an alkyl group, or an aryl group. n shows the integer of 1-10. The substituents R ^{11 to} R ¹³ and R ^{14 to} R ¹⁶ 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 ¹¹ is —O— is preferable, and R ¹¹ and R ¹⁶ are particularly a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ^{12 to} R ^15. A compound in which is a hydrogen atom and n is an integer of 1 to 4 is particularly preferably used. A preferable compounding amount is 30 to 130% by mass, more preferably 50 to 100% by mass with respect to the thermoplastic resin. This compound may be used alone or in combination of two or more.

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 ¹⁷ 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 ¹⁷ 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 a 7 to 20 carbon atom. An arylcarbonyl group is more preferred. 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. A preferable compounding amount is 30 to 130% by mass, more preferably 50 to 100% by mass with respect to the thermoplastic resin. This compound may be used alone or in combination of two or more.

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 ¹⁸ and R ¹⁹ represent a hydrogen atom, a halogen group, an alkyl group having 4 or less carbon atoms, or an alkoxy group. X ¹² 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) Dibenzyl oxalate (2) Di (p-methylbenzyl) oxalate
(3) Oxalate di (p-chlorobenzyl)
(4) Oxalic acid di (m-methylbenzyl)
(5) Dioxalate (p-ethylbenzyl)
(6) Dioxalate (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 dibenzyl oxalate, di (p-methylbenzyl) oxalate, di (p-chlorobenzyl) oxalate, di (m-methylbenzyl) oxalate, and dioxalate. (P-ethylbenzyl) and di (p-methoxybenzyl) oxalate. A preferable compounding amount is 30 to 130% by mass, more preferably 50 to 100% by mass with respect to the thermoplastic resin. This compound may be used alone or in combination of two or more.

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

In the above formula, R ²⁰ , R ^{20 ′} , R ²¹ and R ^{21 ′} 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-diphenoxymethylbenzene (2) 1,3-diphenoxymethylbenzene (3) 1,4-di (2-methylphenoxymethyl) benzene (4) 1,4-di (3-methyl Phenoxymethyl) benzene (5) 1,3-di (4-methylphenoxymethyl) benzene (6) 1,3-di (2,4-dimethylphenoxymethyl) benzene (7) 1,3-di (2,6 -Dimethylphenoxymethyl) benzene (8) 1,4-di (2-chlorophenoxymethyl) benzene (9) 1,2-di (4-chlorophenoxymethyl) benzene (10) 1,3-di (4-chloro Phenoxymethyl) benzene (11) 1,2-di (4-octylphenoxymethyl) benzene (12) 1,3-di (4-octylphenoxymethyl) benzene (13) 1,3-di (4- Isopropyl phenyl phenoxymethyl) benzene (14) 1,4-di (4-isopropylphenyl phenoxymethyl) benzene

  Among these exemplified compounds, preferred specific examples include 1,2-diphenoxymethylbenzene, 1,4-di (2-methylphenoxymethyl) benzene, 1,4-di (3-methylphenoxymethyl) benzene, 1,4-di (2-chlorophenoxymethyl) benzene is mentioned. A preferable compounding amount is 30 to 130% by mass, more preferably 50 to 100% by mass with respect to the thermoplastic resin. This compound may be used alone or in combination of two or more.

  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). These may be used alone or in combination.

  The compounds represented by the above general formulas (1) to (4) are substances that are solid at room temperature, but are preferably used after being subjected to 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, a sand mill, or the like, which is a wet dispersion method generally used at the time of coating production, can be used. In the bead mill, ceramic beads such as zirconia, titania and alumina, metal beads such as chrome and steel, and glass beads 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.

  For the purpose of preventing the sticking phenomenon, a heat-meltable substance may be used in the layer constituting the surface on the image drawing side of the heat-sensitive lithographic printing plate according to the present invention. As the hot-melt material, an organic compound having a melting point of 50 to 150 ° C. is preferable. For example, waxes such as carnauba wax, microcrystalline wax, paraffin wax, polyethylene wax, lauric acid, stearic acid, oleic acid, palmitic acid, behen. Acids, fatty acids such as montanic acid, and esters and amides thereof can be used.

  The heat-sensitive lithographic printing plate according to the present invention may be provided with an undercoat layer in order to improve the adhesion between the image forming layer and the support as described above. The layer constituting the image drawing side surface of the heat-sensitive lithographic printing plate according to the present invention may contain an inorganic substance such as titanium dioxide, silicon dioxide, aluminum oxide or the like for the purpose of preventing printing stains. The ratio to be contained is appropriately determined in a desired range depending on various conditions such as printing ink, dampening water, printing speed, and printing pressure used for printing.

  The heat-sensitive lithographic printing plate according to the present invention is provided with a function of improving conductivity and antistatic property as necessary, an anti-curl layer for preventing curling as a printing plate, and a curl promoting layer for imparting desired curling. Etc. can be provided in plural.

  In the layer constituting the heat-sensitive lithographic printing plate according to the present invention, two or more anionic, cationic, betaine or nonionic surfactants may be used in combination as a coating aid, a matting agent, Thickeners and antistatic agents can also be used.

  As the water-resistant support, for example, a plastic film, resin-coated paper, water-resistant paper or the like can be used. Specifically, polyolefins such as polyethylene and polypropylene, polyethersulfone, polyester, poly (meth) acrylate, polycarbonate, polyamide, and polyvinyl chloride plastic film, resin-coated paper with these plastics laminated or coated on the surface, melamine Paper that has been water-resistant by a wet paper strength agent such as formaldehyde resin, urea formaldehyde resin, or epoxidized polyamide resin can be used.

  The thickness of the support is preferably about 100 to 300 μm from the viewpoint of the recording suitability of the thermosensitive plate making apparatus and the lithographic printing press suitability. In addition, the surface of these supports can be subjected to a surface treatment for improving adhesion with a layer coated as an upper layer, or can be subjected to a dyeing treatment for improving visibility. The preferred support in the present invention is resin-coated paper or polyethylene terephthalate.

  The surface of such a water-resistant support may be subjected to treatments such as plasma treatment, corona discharge treatment, deep ultraviolet irradiation treatment, and subbing treatment in order to enhance adhesion with the image forming layer. The subbing layer provided on the water-resistant support by the subbing treatment is composed of an acetal resin such as polyvinyl butyral, a polyester resin having a hydroxyl group at the end of the molecular chain, (meth) acrylic acid / (meth) acrylic acid ester A resin selected from a polymer, a vinylidene chloride / vinyl chloride copolymer, and the like can be contained. The thickness of the undercoat layer is usually about 0.1 to 10 μm in dry film thickness.

  The layer constituting the heat-sensitive lithographic printing plate according to the present invention is produced by coating and drying a coating liquid prepared by mixing each material and dissolving or dispersing in an appropriate solvent on a support by a known coating method. To do. The preferred solvent is water, but in order to prevent the image forming layer (and the intermediate layer) from being thermally denatured by the heat during drying, the drying treatment is preferably performed in an atmosphere of 50 ° C. or lower for about 30 seconds to 10 minutes. .

  Hereinafter, the present invention will be described in detail with reference to examples. In the description, “parts” and “%” are based on mass unless otherwise indicated.

Example 1
A double-sided polyethylene-coated paper (RC paper) with a thickness of 150 μm is corona discharge processed, and then coated with an outermost layer (image forming layer) coating liquid having the following formulation, and a thermal planographic plate having an outermost layer with a dry film thickness of 3 μm A printing plate was prepared.

<Outermost layer coating solution>
Water-soluble polymer compound: gelatin (12% aqueous solution) 80 parts (Nippi IK3000)
-Fine particles of thermoplastic resin; carboxy-modified styrene-butadiene copolymer (solid content 45%)
(DIC Co., Ltd., Luck Star 7132-C) 30 parts, 1,2-bis (3-methylphenoxy) ethane (Sanko Co., Ltd. KS-232) dispersion (30% dispersion) 30 parts, developer; 4-hydroxy-4-isopropoxydiphenyl sulfone (Nippon Soda Co., Ltd. D-8) dispersion (30% aqueous dispersion) 30 parts, color former; 3-dibutylamino-6-methyl-7-anilinofluorane (Yamamoto Kasei Co., Ltd. ODB2) Dispersion (30% aqueous dispersion) 9 parts, Hardener; 1.2 parts divinyl sulfone

The heat-sensitive lithographic printing plate prepared by the above method is used in a test printing mode (printing speed 2 inches / second, applied energy 18.6 mJ / second) of a direct thermal printer (Toshiba TEC barcode printer B-433 line type thermal head 300 dpi). mm ² ). Images were recorded.

  Next, the following plate surface treatment liquid (the solvent used is shown in Table 1) is prepared, and for each printing plate, each plate surface treatment solution is included in absorbent cotton so that the entire plate surface is uniform. Was granted. In Table 1, No. 1 and no. The plate surface treatment solution of No. 2 was obtained by removing Snowtex C from the following plate surface treatment solution.

<Plate processing solution>
-Pure water: 870 parts-pH buffering agent: 10 parts of monobasic hydrogen phosphate dihydrate-Solvent (shown in Table 1): 40 parts-Snowtex C (Nissan Chemical Industry Co., Ltd. colloidal silica dispersion (oxidation) As a 20% dispersion, particle size 10-20 nm)): 80 parts

  Each printing plate to which the plate surface treatment solution was applied was left for one day and night, and the decolored state of the image was evaluated. In addition, each printing plate left for one day and night is subjected to an offset printing press (RYOBI 3200CCD: Ryobi Imagics Co., Ltd.), ink; New Champion F-Gloss ink S: DIC Co., dampening solution; SLM-OD: 5000 sheets were printed using a 10% dilution of Mitsubishi Paper Industries Co., Ltd., printing performance was evaluated, and the results are summarized in Table 1.

The evaluation of the decolored state of the image and the printing performance was performed according to the following criteria, and the results are summarized in Table 1.
-Image erasing state: ○ (good) if the image is at a level that does not change at all, △ if the image density and the non-image part are clearly distinguishable, although the image density is slightly reduced, the image is erased If the image is colored and the image and the non-image portion cannot be distinguished, the mark is x (defect).
-Printing performance:
<Ink ride>
From the start of printing, the number of printed sheets discharged from the printing press reaches an appropriate image density. If the number of printed sheets reaching the appropriate image density is 0 to 10th, ○ (good), 11 to 50th sheet If it was △, it was rated as x (defect) if it was 51st or more.
<Print stain>
Regarding the number of printed materials discharged from the printing press immediately after the start of printing, the paper is a good paper: 0 (good) if it is 0-10, △ if it is 11-50, × if it is 51st or more (Defect).
<Print durability>
Print 5000 sheets and observe the image part in the printed matter. If the density is not lowered, it is ◯ (good), if the density is slightly lowered or partially missing, Δ (somewhat Good). In the case of a level that is clearly deteriorated, x (defect) was assigned.

(Example 2)
In place of Snowtex C of Example 1, a plate surface treatment solution was prepared in the same manner except that alumina sol 100 (Nissan Chemical Industry Co., Ltd. alumina dispersion (20% dispersion as oxide, particle size 10 to 20 nm)) was used. When manufactured and evaluated for the color erasing state and printing performance of the image in the same manner as in Example 1, almost the same results as in Table 1 were obtained except that the print stain was slightly inferior.

  As is apparent from the above results, according to the printing method of the present invention, when the plate surface treatment liquid is applied to the plate surface, the image is not decolored, and there is a problem in ink loading when the image portion is printed. Without giving, the printing stain is improved.

Claims (1)

A heat-sensitive lithographic printing plate having an image-forming layer containing at least a thermoplastic resin, a water-soluble polymer compound, a developer and a color former on a water-resistant support is image-wise heated or irradiated with light. A printing method of a heat-sensitive lithographic printing plate, comprising printing after applying a plate surface treatment liquid containing the following compounds (i) and (ii) before starting printing.
(I) Inorganic fine particles (ii) A polyol compound having a boiling point of 180 ° C. or more and 4 or less carbon atoms