JPS61148097A - Direct drawing type offset printing plate blank - Google Patents

Abstract

PURPOSE:To prevent contamination in printing from occurring, by a method wherein a coating liquid for forming an image-receiving layer is applied to a water-resistant base, and a solution of a specified metallic compound is applied thereto to provide an overcoat layer. CONSTITUTION:The coating liquid for forming the image-receiving layer containing an inorganic pigment such as kaolin and silica, a water-soluble binder and a water-resisting agent or the like is applied to the water-resistant base, followed by drying to provide the image-receiving layer in a thickness of 3-20mum. Thereafter, a solution containing a compound comprising Be, Mg, Zn or the like as a metallic compound capable of forming a hydrophilic and water-insoluble precipitate on reaction with a hydrophilic nature imparting liquid comprising a hexacyanometallic acid salt and ammonium phosphate is applied to the image-receiving layer to provide the overcoat layer. Accordingly, the image-receiving layer can be obtained which is not liable to generate contamination in printing due to rubbing of a thermal transfer ink layer against the peripheral areas of printed parts by a thermal printing head in the process of plate making by a thermal transfer printer.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a direct-printing type offset printing original plate, which can be made using a thermal transfer printer such as a Japanese word processor or suno and does not cause printing stains. , relates to a direct printing type offset printing original plate having good printing durability.

Offset printing plates currently used in the light printing field include (1) direct printing type plates with an image-receiving layer on a water-resistant support, and (2) a photoconductive layer on a water-resistant support. (3) A silver salt photographic type in which a silver halide emulsion layer is provided on a water-resistant support. Among these, the above printing plate (1) can be handwritten with lipophilic ink on the image-receiving layer, printed with a printer, or plate-made directly with a PPC copying machine, so other (2) above, There are some advantages compared to the original printing plate (3).

Recently, with the advancement of OA and the high performance of Japanese word processors (document creation, editing proofreading, printing mechanism), it is now possible to directly make a plate from the printer by inputting the manuscript into the Japanese word processor using the master plate of (1) in the office. There is an increasing trend towards offset printing. Printer printing methods include wire tod, shuttle, type, laser, thermal transfer, etc., but 1" book 1i1! ! Word processing sensors often use a serial wire tod or serial thermal transfer method.

(B) Prior art The conventional direct printing type offset printing original plate was
581, JP-A-48-9802, JP-A-57-205
198 # Many products have been released, and generally, a hydrophilic and water-resistant image-receiving layer is created by coating an image-receiving layer coating liquid consisting of an inorganic pigment, a water-soluble binder, a water-resistant agent, etc. on a water-resistant support. was used. When this printing plate is made into plates by a thermal transfer printer, that is, when the thermal printer head prints characters or figures line by line on the printing plate surface via a thermal transfer ink ribbon, the thermal ink ribbon also rubs the periphery of the printed area at the same time. There was a drawback that stains were easily generated on the outside of the printing part, and when this was printed, the stained areas clearly became printed stains. Even if you desensitize the plate surface with a commercially available hydrophilic liquid for fax masters,
The thermal transfer ribbon ink around the printing area cannot be removed,
It was not possible to reduce printing stains. Therefore, attempts have been made to add zinc oxide to the image-receiving layer of a direct drawing type offset printing original plate to strengthen the desensitizing effect of the hydrophilic liquid and eliminate stains. However, even with this method, printing stains could not be completely eliminated.

(C) Object of the Invention The object of the present invention is 1. During plate making using a thermal transfer printer such as a Japanese word processor, a print plate having an image-receiving layer that is less likely to cause printing stains caused by thermal transfer ink being rubbed around the printing area by a thermal printer head. The purpose of the present invention is to provide a patterned offset printing original plate.

Another object of the present invention is to prevent staining of the image receiving layer from thermal transfer ink around the printed area by the thermal printer head.
To provide a direct printing type offset printing original plate which can be easily removed with a hydrophilic liquid and can produce clear printed matter without stains from the initial stage of printing.

Furthermore, another object of the present invention is to provide a direct printing type offset printing original plate having good rigidity resistance.

(0) Structure of the Invention The direct-printing type offset printing original plate of the present invention is produced by coating an image-receiving layer coating solution containing an S-machine pigment, a water-soluble binder, and a water-resistant agent on a water-resistant support, and then applying a hexacyanometallic acid An overcoat layer is provided by applying a solution made by dissolving a metal compound that reacts with a wood-loving solution consisting of salt and/or ammonium phosphate to form a hydrophilic and water-insoluble precipitate. It is characterized by

Hexacyanometallates such as hexacyanocobalt (
II), (III) s, a metal that forms a hydrophilic and water-insoluble precipitate by reacting with a hydrophilic solution consisting of an alkali metal salt such as ferrocyanic acid or ferricyanic acid or/and ammonium phosphate. Compounds include Be, Mg, Zn, Hg, In, Cu,
Ag, AI, T1. Th, Sn, Pb, B
i, Zr, Co, Cr, Cd, Ni, Fe, M
Examples include compounds containing either Zn or Ga(7), but Zn compounds, which have a strong reaction with the above-mentioned lignification solution, are particularly preferred in the present invention.

Also, some of the alkali metals and alkaline earth metals (Ca,
Compounds Sr and Eta) cannot be used in the present invention because they do not form water-insoluble precipitates even when they react with the wood-loving solution.

The above-mentioned metal compound may be dissolved in water or a water-soluble organic solvent such as alcohol such as methanol or ethanol, and applied to the fabric.Also, colloidal silica or other synthetic material may be used to improve the adhesion of the metal compound to the image-receiving layer. Silica may be added to form an overcoat layer coating solution.

As the inorganic pigment for the image-receiving layer, kaolin alone or a mixture of kaolin and other inorganic pigments can be used, but a mixture of kaolin and synthetic silica is particularly preferred. Kaolin is generally used for paper coating. Things can be used. The chemical composition of kaolin is aluminum silicate, and it has the shape of fine hexagonal plates. Synthetic silica used in combination includes:
Although there are synthetic silicon compounds mainly composed of silicic acid such as white carbon, silica sol, colloidal silica, silica gel, and synthetic molecular sheep, several amorphous synthetic silicas are preferred in the present invention.

Water-soluble binders for the image-receiving layer include starch or starch derivatives, cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, casein, vinyl acetate-crotonic acid copolymer, polyammonium acrylate, and especially acetic acid. Completely saponified products of vinyl-maleic anhydride copolymer, completely saponified products of vinyl acetate-versatic acid copolymer, completely saponified products of vinyl acetate-acrylamide copolymer, vinyl acetate and ethylenic monomers containing silicon in the molecule. Modified polyvinyl alcohol such as a completely saponified product of a copolymer with a saturated monomer, 7cetoacetylated product of completely saponified polyvinyl alcohol (acetoacetylated polyvinyl alcohol), and the like are preferred.

Furthermore, aldehydes, amines, melamine-formalin resin, urea-formalin resin, hydrazides, water-resistant agents such as persulfate, or antifoaming agents may be added to the image-receiving layer.

As mentioned above, the original plate of the present invention has a configuration in which an image-receiving layer and an overcoat layer are provided on a water-resistant support, and the water-resistant support used here is melamine. formalin resin, urea formalin resin,
Examples include high-quality paper moist-strengthened using polyamide epichlorohydrin resin, resin coated paper, plastic film, and the like.

To make the direct printing type offset printing original plate according to the present invention,
Inorganic pigments made of kaolin, silica, etc.

An image-receiving layer coating solution containing a water-soluble binder, a water-resistant agent, etc. is coated on a water-resistant support and dried to form an image-receiving layer with a thickness of about 3 to 20 IL, and then a solution containing the metal compound dissolved therein is formed. may be applied to form an overcoat layer.

In this case, a water-resistant intermediate layer may be provided between the support and the image-receiving layer to further improve printing durability, and a back coat layer may be added to prevent curling on the back side of the support. may be provided.

As the intermediate layer (1 to 20 tons thick), acrylic resin, SBR
, MBR, NBR1, emulsion type resins such as vinyl acetate-dethylene copolymer, or solvent-soluble resins such as epoxy resins, polyvinyl butyral, polyvinyl acetate, polyvinyl chloride, etc. may be used alone or in combination of two or more. Also, a suitable amount of pigment may be added to this intermediate layer.

The back coat layer (thickness 1 to 204 mm) may be starch or starch derivatives, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, polyvinyl alcohol, casein, vinyl acetate-crotonic acid copolymer, and water-soluble resins such as ammonium polyacrylate. , or emulsion type resins such as acrylic resins, SBR, and MBR1 vinyl acetate-ethylene copolymers may be used alone or in combination of two or more. A suitable amount of pigment may also be added to this backcoat layer.

(E) Examples The present invention will be explained in more detail by way of examples.

Example 1 An intermediate layer coating solution having the following composition was coated on the surface of a support (100 g/rn' wet reinforced paper) and dried to form an intermediate layer of about 15 g/m''.

[Intermediate layer coating liquid]

Carboxyl-modified SBR latex (solid content 50%) 120 parts 10% aqueous solution of oxidized starch IOO parts 5 parts of gicrite
200 parts of 0% aqueous dispersion (sericite content 35%)
Inorganic pigment, manufactured by Zeeklite Chemical ■) 12 parts of 80% aqueous solution of melamine resin (product name: Sumirezu Resin-613, manufactured by Jumin Chemical ■) 1.2 parts of 35% aqueous solution of curing catalyst (product name: Accelerator AC: X-P) (manufactured by Sumitomo Chemical Co., Ltd.) Next, on the back side of this support, a coating solution for a Yatsuku coat layer having the following composition was applied and dried to form a back coat layer of about 15 g/ln' to obtain a water-resistant support.

[Back coat layer coating liquid]

SBR latex 10 parts (solid content 50%) 50 parts of a 10% aqueous solution of polyvinyl alcohol (trade name: Tararebovar 117, manufactured by Kuraray ■) 50% aqueous dispersion of kaolin 100 parts Melamine resin 8
0% aqueous solution 2 parts 10% ammonium chloride
Aqueous solution 2 parts water
50 parts Next, an image-receiving layer coating solution having the following composition was applied thereon and dried to form an image-receiving layer of about 8 g/rn'.

[Image-receiving layer coating liquid]

100 parts of a 50% dispersion of kaolin (trade name Ultra White-90, manufactured by Engelhard) 250 parts of a 20% dispersion of synthetic silica (trade name Thyroid 308, manufactured by Fuji Davison Chemical) 200 parts of a 10% aqueous solution of polyvinyl alcohol (Product name: Kuraray Bobal 117, manufactured by Kuraray ■) 80% aqueous solution of melamine resin 2.5 parts (Product name: Sumirezu Resin-613, manufactured by Sumitomo Chemical ■) 10% aqueous solution of ammonium chloride 2 parts water
Further, 60 parts of this was coated with an overcoat layer coating solution having the following composition and dried to form an overcoat layer of about 0.5 g/rn'.

[Overcoat layer coating liquid]

Zinc chloride 1 part water
99 copies When this direct printing type offset printing original plate was made into a printing plate using a Canon Japanese word processor Canode 45s (manufactured by Canon ■) thermal transfer printer, there was little transfer of thermal transfer ink around the printed area. When printed using an automatic offset printing machine (Gestera Toner 333, manufactured by Gestella Toner), the stains around the printed area were completely removed by the hydrophilic liquid mainly composed of potassium ferrocyanide and ammonium phosphate during the etching process, and from the beginning of printing. More than 500 clear prints were obtained.

Comparative Example 1 A direct-printing offset printing original plate was obtained in the same manner as in Example 1 except that the overcoat layer of Example 1 was not applied. When this original plate was plate-made using the thermal transfer printer of Example 1, a considerable amount of thermal transfer ink was observed to be transferred around the printed area. Further, when printing was performed using an offset printing machine, even the hydrophilizing liquid could not remove stains sufficiently, and only printed matter with considerable printing stains around the printed area was obtained.

Example 2 A straight horizontal offset printing original plate was obtained in the same manner as in Example 1, except that the overcoat layer coating liquid in Example 1 was replaced with the following coating liquid. When this master plate was made using a thermal transfer dot printer, there was very little transfer of thermal transfer ink around the printed area.

When this was printed using an automatic offset printing machine,
The hydrophilic liquid completely removed stains around the print area, and more than 500 clear prints were obtained from the beginning of printing.

[Overcoat layer coating liquid]

Zinc chloride 1 part Colloidal silica (solid content 20%) 20 parts Water
79 parts Example 3 A direct-printing offset printing original plate was obtained in the same manner as in Example 1 except that zinc chloride in the overcoat layer coating solution in Example 1 was replaced with the same amount of zinc acetate. When this master plate was made using a thermal transfer printer using a Japanese word processor NECNWP-13N (manufactured by NEC ■), there was very little transfer of thermal transfer ink around the printing area.When this was printed using an automatic offset printing machine, The stains around the printing area were completely removed by the chemical solution, and more than 500 clear prints without any printing stains were obtained from the beginning.

CF) Effects of the Invention As is clear from the examples, the direct printing type offset printing original plate of the present invention has no printing stains around the printed area from the initial printing stage even when plate-making is performed using a thermal transfer printer, and the printing durability of the printed area is high. Because of its good quality, it is of great value as a direct printing type offset printing original plate for plate making using a thermal transfer printer.

Claims (1)

[Scope of Claims] 1. After coating an image-receiving layer coating solution containing an inorganic pigment, a water-soluble binder, and a water-resistant agent on a water-resistant support, a layer of hexacyanometallate or/and ammonium phosphate is applied thereon. 1. A direct-printing type offset printing original plate, characterized in that a solution made by dissolving a metal compound that reacts with a hydrophilic liquid to form a hydrophilic and water-insoluble precipitate is coated. 2 Claim 1 in which the metal compound is a zinc compound
Direct printing type offset printing original plate described in Section 2.