JP2006212833A - Direct printing type lithographic printing original plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct printing type lithographic printing original plate excellent in plate wearability and staining properties. <P>SOLUTION: The direct printing type lithographic printing original plate comprises an undercoating layer including a binder and a pigment, and an image forming layer substantially including no polymeric binder on a support in the order, wherein the image forming layer includes a pigment which be united with the binder in the undercoating layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a direct-drawing lithographic printing plate capable of directly making a printing plate with a thermal printer using a hot-melt transfer recording medium (ink ribbon), and more particularly to a direct-drawing lithographic plate excellent in printing durability and water retention. It relates to a printing plate material.

  With the recent development of computers and peripheral devices, a planographic printing plate making method using various digital printers has been proposed. Such a lithographic printing plate is made by a dry electrophotographic laser printer due to the difference in the image portion forming method (JP-A-6-138719, JP-A-6-250424, JP-A-7- 1847), plate making using an on-demand ink jet printer using hot melt ink (Japanese Patent Laid-Open No. 9-58144), plate making using a thermal printer using a thermal transfer ink ribbon (Japanese Patent Laid-Open No. 63-166590). Issue).

  Unlike the conventional plate-making method of a lithographic printing plate in which a silver halide photosensitive material or a photosensitive resin is applied to a water retention-providing surface, the plate-making method using the above-mentioned various digital printers has no restrictions on safety light in handling, and the image There is an advantage that a lithographic printing plate can be easily and easily made in that no development treatment with an aqueous developer after recording is required.

  These direct-drawing lithographic printing plates have a structure in which a hydrophilic image forming layer is provided on a support such as paper or plastic film, and since the ink of a digital printer is oleophilic, the printing portion Becomes an image-providing image portion, and the non-printed portion becomes a non-image portion by holding the moisturizing liquid, thereby enabling offset printing.

  In a direct-drawing lithographic printing plate using a flexible support such as paper or plastic, such as JP-A-48-9802 and JP-A-57-205196, the hydrophilic non-image portion has a hydrophilic polymer and a hydrophilic inorganic Consists of pigments. The hydrophilic polymer described in these publications is an organic substance, that is, a hydrocarbon derivative, and has a property that a hydrophobic portion is inevitably contained in the molecule. For this reason, anodized aluminum, which is an inorganic substance, is used as the non-image part, and the so-called PS plate that does not use the hydrophilic polymer as the non-image part has different resistance to printing stains, so it cannot be printed under the same conditions. There was a problem that even if it was going to print with the same printing machine as the PS plate, it took troublesome work such as changing dampening water. Furthermore, lithographic printing plates with hydrophilic polymers have the property of having this hydrophobic portion, so if stains occur once with printing during printing, it takes time until the stains on the plate material are recovered. However, there is a problem that the plate has to be replaced if the stain is not recovered.

In order to solve this problem, Japanese Patent Application Laid-Open No. 63-166590 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2001-270261 (Patent Document 2) use inorganic compounds and alkoxysilanes as water-proofing agents for hydrophilic polymers. When water resistance is achieved using a known water-resistant agent such as glyoxal or formalin, the polymer is bonded by linking the hydrophilic group, but the bonded hydrophilic group is destroyed and the site is hydrophobic. Become. These publications exclude the harmful effects. However, it only stops the reduction of hydrophilic groups and does not solve the above-mentioned problem. Further, in the re-published patent WO01-045959 (Patent Document 3), the amount of the binder used as the non-image portion is smaller than that of the pigment. It is not a solution to this problem.
JP 63-166590 A (first page) JP 2001-270261 A (first page) Republished patent WO01-045959 (1 page)

  An object of the present invention is to provide a direct-drawing lithographic printing original plate excellent in printing durability and stain resistance.

  The above object of the present invention is to have an undercoat layer containing a binder and a pigment on the support and an image forming layer containing substantially no polymer binder in this order, and the image forming layer is a binder for the undercoat layer. It was achieved by using a direct-drawing type lithographic printing original plate characterized by containing a pigment capable of binding to.

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

  In the present invention, the undercoat layer and the image forming layer are formed on the support in this order, and the image forming layer forms the outermost layer.

  In the present invention, the image forming layer is mainly composed of a pigment that does not substantially contain a binder. The phrase “substantially free of binder” means that water-soluble molecules having a molecular weight of 10,000 or more are 5% by weight or less, preferably 2% by weight or less in terms of solid content with respect to the pigment. The binder is preferably not contained at all, but it is preferable to use a minimum amount within this range when necessary for modification or dispersion of the pigment.

  In the present invention, the pigment capable of binding to the binder means that a 5% by weight binder polymer aqueous solution and a 10% solid pigment aqueous dispersion are mixed at a ratio of 1: 1 and gelled within 5 minutes. .

As the pigment of the image forming layer used in the present invention, known pigments can be used, but inorganic pigments such as silica, alumina sol, zirconia sol, clay and kaolin are preferable. The particle diameter of the pigment is 10 nm to 10 μm, preferably 10 nm to 1 μm, more preferably 100 nm to 500 nm, and the shape can be spherical, feathered, or any other shape, and it is particularly preferable to use a porous pigment. If the amount of pigment used is too small, the undercoat hydrophilic polymer may appear on the surface and cause printing stains. When the image forming substance such as a hot-melt transfer material is bound to this pigment, the adhesion of the image area is weakened, so that the pigment particles uniformly cover the plate surface with a single layer. Is ideal. This state varies depending on the specific gravity, shape, and surface roughness of the subbing, but a pigment usage of 50 to 300 mg / m ² is preferred. Also, a plurality of types of pigments or the same type of pigments having different particle diameters can be used at the same time.

  The pigment particles of the image forming layer used in the present invention preferably have a zeta potential opposite to the charge of the polymer of the undercoat layer in order to be sufficiently strongly adsorbed by the polymer of the undercoat layer. The zeta potential is a portion that effectively acts on the electrokinetic phenomenon in the potential difference at the interface between the solid and the liquid, and is described in detail in, for example, “Distributed Technology Comprehensive Document Collection” (published by Management Development Center Publishing Department) P90-96. . When a pigment having the same charge as that of the undercoat layer is used, a dispersant having a charge opposite to that of the undercoat layer is used as disclosed in JP-A-2004-276466 in order to have a zeta potential opposite to that of the undercoat layer. It can also be used to make a pigment dispersion and to alter its zeta potential. In this case, when a polymer dispersant is used as the dispersant, as described above, the content of the dispersant must be 5% by weight or less, preferably 2% by weight or less in terms of solid content with respect to the pigment. In the present invention, as a dispersant used for zeta potential modification, the dispersant described in JP-A-2004-276466 can be used when it is transformed into a cation. In the case of conversion to an anion, examples of the dispersant include an anionic polymer such as polyacrylic acid, carboxymethyl cellulose, polystyrene sulfonic acid, polyphosphonic acid, carrageenan, alginic acid, gum arabic, maleic acid and styrene copolymer, maleic acid and Styrene sulfonic acid copolymer, maleic acid and methyl vinyl ether copolymer and the like can be used.

  In addition to the inorganic pigment, the image forming layer used in the present invention may contain a surfactant, a dye for visibility and an organic pigment.

  In the present invention, the binder constituting the undercoat layer may be a water-soluble polymer (hereinafter referred to as an anionic or cationic polymer) having a larger number of ionic groups having one anionic or cationic charge than the opposite charge. Is preferably used. Examples of polymers having an anionic group include polyacrylic acid, carboxymethyl cellulose, polystyrene sulfonic acid, polyphosphonic acid, carrageenan, alginic acid, gum arabic, maleic acid and styrene copolymer, maleic acid and styrene sulfonic acid copolymer, maleic Known acids such as acid and methyl vinyl ether copolymer can be used. When an anionic polymer is used, it is preferable that the zeta potential of the pigment of the image forming layer has a positive charge. Examples of the polymer having a cationic group include polydiallyldimethylammonium chloride, polydiallylamine, polymethyldiallylamine, diallyldimethylammonium chloride and acrylamide copolymer, didiandiamide and diethylenetriamine copolymer, diallyldimethylammonium chloride and sulfur dioxide. Known copolymers such as copolymers, diallylamine and sulfur dioxide copolymers, and chitosan can be used. When a cationic polymer is used, it is preferable that the zeta potential of the pigment of the image forming layer has a negative charge.

  Further, in the present invention, it is particularly preferable to use polyallylamine or a polymer containing allylamine, such as a copolymer of allylamine and diallylamine, a copolymer of allylamine and acrylamide, etc., in the undercoat layer. In this case, for example, a cationic pigment can also be used because allylamine has a very high reactivity and forms a strong bond regardless of the zeta potential of the pigment of the image forming layer.

Water-soluble polymers with these ionic groups or the amount of polymer containing allylamine 0.05 to 3 g / m ² as a solid content coating amount, preferably 0.1-2 g / m ^2. In addition, water-soluble polymers formed by coating, such as polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, methylmethylcellulose, hydroxyethylcellulose, hydroxylpropylmethylcellulose, casein, gelatin, agar, dextrin, starch, water-soluble polyurethane, water-soluble nylon, etc. Can also be used. The total amount of water-soluble polymers used is 0.1 to 5 g / m ² , preferably 0.5 to 3 g / m ² . Among them, the anionic or cationic polymer is preferable from the viewpoint of adhesion to the pigment as the proportion of the total binder amount is large, but the preferable ratio varies depending on the polymer used from the viewpoint of film strength and reactivity with the water resistance agent. It is preferable to occupy 5 to 100% of the whole.

  In the present invention, a known water-resistant agent such as a formalin, glyoxal, glutaraldehyde or the like, N-methylolurea, N- Epoxy compounds such as methylol melamine, N-methylol ethylene urea, polyamine, polyisocyanate compound, silane compound, 2,4-dichloro-6-hydroxy-S-triazine salt, 2,4-dihydroxy-6-chloro-S-triazine A compound having an active halogen such as a salt, divinyl sulfone, divinyl ketone, N, N, N-triacroylhexahydrotriazine, or an active three-membered ethyleneimino group or epoxy group in the molecule. Using various compounds such as compounds, dialdehyde starch as polymer hardener To be water-resistant. Although it is necessary to use a water-proofing agent depending on the polymer to be used, aldehydes and polyepoxy compounds are generally preferable because they form a strong bond. The amount used is preferably 1/30 to 1/2 in weight ratio to the binder.

  In the present invention, the undercoat layer is preferably provided with a pigment so as to have printability so that the surface is uneven. The pigment preferably has a particle size larger than that of the pigment of the image forming layer, and has an average particle size of 0.5 to 15 μm, more preferably 1 to 10 μm. The material of the pigment is not particularly limited, and an inorganic or organic mat material can be used. Examples of the inorganic mat material include silica, clay, barium sulfate, and alumina. Examples of the organic mat material include polymethyl methacrylate, polystyrene, polyurethane, benzoguanamine resin, silicone resin, and cellulose acetate. A plurality of mat materials can also be used.

In the present invention, the surface roughness can be adjusted by using a pigment in the undercoat layer and adjusting the pigment in the image forming layer. As the surface roughness, the arithmetic average roughness Ra according to JIS-B0601 is preferably 0.2 to 2.0 μm, more preferably 0.4 to 1.0 μm. In order to obtain this, the amount of pigment used in the undercoat layer naturally varies depending on the particle size and specific gravity of the pigment, but is 0.05 to 1 g / m ² , preferably 0.2 to 0.8 g / m ^2. Is preferably used.

  In the present invention, the undercoat layer may further contain a surfactant, an antistatic agent, a coloring material such as a dye or a pigment, latex, and an antifoaming agent.

  As the support of the lithographic printing plate of the present invention, any material can be used as long as it can withstand lithographic printing such as paper, a synthetic or semi-synthetic polymer film, a metal plate such as aluminum or iron. The surface of the support may be coated on one or both sides with one or more polymer films or metal thin films. The surface of these supports can be surface-treated in order to improve the adhesion with the coating layer.

  Particularly preferably used supports are paper coated with a polyolefin polymer on both sides or one side, a polyester film, a polyester film whose surface is hydrophilized, an aluminum plate subjected to a surface treatment, and the like. These supports may contain solid fine particles for improving surface properties.

  The plate material for lithographic printing according to the present invention includes an undercoat layer and an image forming layer, as necessary, a conductive layer, an antistatic layer, an anti-curl layer for preventing curling of the support, and a curl acceleration for imparting a desired curl. Layers and the like can be provided.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition,% shows the mass% unless there is a notice.

A matted layer containing silica particles with an average particle size of 5μ is provided on one side of 135 g / m ² double-sided polyethylene-coated paper, the following undercoat layer is applied to the opposite side, and image formation is performed on the undercoat layer after drying. The layer was applied to produce a lithographic printing plate. The undercoating amount was 40 ml / m ^{2 for} the coating solution, and the coating amount of the image forming layer was 8 ml / m ^{2 for the} coating solution.

<Undercoat layer A>
PVA235 (partially saponified PVA, manufactured by Kuraray Co., Ltd.) 2 g / m ²
PAA10C (polyallylamine, manufactured by Nittobo Co., Ltd.) 0.2 g / m ²
SY378 (silica powder, manufactured by Fuji Silysia Chemical Ltd.) 0.4 g / m ²
Glyoxal (40% aqueous solution) 0.5 g / m ²

<Undercoat layer B>
PVA235 1g / m ²
Unisense FPA1001L (diallyldimethylammonium chloride homopolymer, manufactured by Senka Co., Ltd., 47% aqueous solution) 2.1 g / m ²
SY378 (silica powder) 0.4 g / m ²
Glyoxal (40% aqueous solution) 0.5 g / m ²

<Undercoating layer C>
Serogen WS-C (carboxyl methyl cellulose, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 2 g / m ²
SY378 (silica powder) 0.4 g / m ²
Denacol EX311 (epoxy resin, manufactured by Nagase ChemteX Corp.) 0.5 g / m ²

<Image forming layer A>
Aerosil 200 (silica powder, manufactured by Nippon Aerosil Co., Ltd.) 0.12 g / m ²
Swanol AM (betaine surfactant, manufactured by Nippon Surfactant Co., Ltd.)
0.01 g / m ²

<Image forming layer B>
Aerosil 200 0.12 g / m ²
Swanol AM 0.01g / m ²
Charol DC902P (dimethyldiallylammonium chloride homopolymer, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., average molecular weight 9000) 0.0036 g / m ²

<Image forming layer C>
Aerosil 200 0.12 g / m ²
Swanol AM 0.01g / m ²
PVA235 0.012 g / m ²

<Image forming layer D>
Swanol AM 0.01g / m ²
PVA235 0.012 g / m ²

<Image forming layer E>
Snowtex PSM (Colloidal silica, manufactured by Nissan Chemical Industries, 20%)
0.5g / m ²
Swanol AM (betaine surfactant, manufactured by Nippon Surfactant Co., Ltd.)
0.01 g / m ²

<Image forming layer F>
Alumina sol # 200 (alumina sol, manufactured by Nissan Chemical Industries, Ltd., 10%) 1.2 g / m ²
Swanol AM (betaine surfactant, manufactured by Nippon Surfactant Co., Ltd.)
0.01 g / m ²

  A lithographic printing plate was prepared by combining the undercoat layer and the image forming layer as shown in Table 1. In addition, the pigment dispersion liquid (10% in solid content) of the image forming layer and the 5% aqueous binder solution of the undercoat layer are mixed, and the gelled one is described as ◯, and the one not formed as x.

  The produced lithographic printing plate was printed using a RUPO JW05PV (manufactured by Toshiba Corporation, serial type thermal head) word processor, and a printing test was conducted using an H234c (Hamada Printing Machinery Co., Ltd.) offset printing machine. As a printing durability test, ink was printed using New Champion Ink H (Dainippon Ink Chemical Co., Ltd.) and 2% aqueous solution of Toho H liquid (Niken Chemical Co., Ltd.) as a dampening solution. Further, as a stain test, a printing test was performed in the same manner as the printing durability test except that the ink was changed to New Champion Purple S (manufactured by Dainippon Ink & Chemicals, Inc.). As the evaluation method, the printing durability is the number of sheets at which blurring starts to occur, the stain is 2,000 sheets after printing, and the blanket has almost no ink, the blanket is slightly dirty but the printed matter is not stained △, the printed matter is also dirty ×. The results are shown in Table 2.

  From Table 2, a lithographic printing plate using a binder and a binder that can be combined with the pigment used in the image forming layer in the undercoat layer has good printing durability and stain resistance. I understand that. Furthermore, it can be seen that when polyallylamine is used for subbing, it has good printing durability and stain resistance regardless of the zeta potential of the pigment of the image forming layer.

Claims (3)

  A pigment having an undercoat layer containing a binder and a pigment and an image forming layer substantially free of a polymer binder in this order on the support, the image forming layer being capable of binding to the binder of the undercoat layer. Direct drawing type lithographic printing original plate characterized by containing.   2. The direct-drawing lithographic printing plate precursor according to claim 1, wherein a water-soluble polymer having a group having a charge opposite to the zeta potential of the pigment used in the image forming layer is used as a binder for the undercoat layer.   2. The direct-drawing lithographic printing original plate according to claim 1, wherein polyallylamine is contained as a binder for the undercoat layer.