JPH0517871B2 - - Google Patents

Description

[Detailed Description of the Invention] (A) Field of Industrial Application The present invention relates to a direct-printing type lithographic printing original plate, and more specifically, to a plate-making plate that can be directly made using an oil-based ink, a typewriter, a wire dot printer, a thermal transfer printer, a PPC copying machine, etc. Concerning a possible direct plate printing plate.

Currently, the planographic printing original plates used in the light printing field include (1) direct printing type with an image-receiving layer provided on a water-resistant support, and (2) photoconductive printing plates on a water-resistant support. and (3) a silver salt photographic type in which a silver halide emulsion layer is provided on a water-resistant support. Above all, the original printing plate mentioned in (1) above is made by handwriting with oil-based ink on the image-receiving layer or
Since plate making can be done directly with a PPC copier,
It has advantages compared to the other printing master plates mentioned in (2) and (3) above.

Recently, with the spread of office automation equipment, particularly word processors, there has been a demand for a direct plate lithographic printing original plate that can be used for direct plate making and printing. When making plates using a word processor, impact printing printers such as type type or wire dots are often used, and oil-soluble dyes,
Printing is performed directly on the original plate for direct drawing type lithographic printing via a cloth ink ribbon impregnated with printer ink made of mineral oil or the like. The printer ink transferred by printing is fixed on the image-receiving layer and exhibits lipophilic properties, forming an image area during printing. In order to obtain clear printed matter, it is important that the image-receiving layer of the direct-drawing lithographic printing original plate has good fixing properties for the transferred printer ink.

(B) Prior art Conventional direct plate printing plates generally consist of an inorganic pigment such as kaolin clay or zinc oxide, a hydrophilic binder such as polyvinyl alcohol, starch, or carboxymethyl cellulose, and melamine formaldehyde on a water-resistant support. Those provided with an image-receiving layer containing a crosslinking agent such as a resin were used.

This image-receiving layer is required to have hydrophilicity, water resistance, and in addition, fixability to oil-based inks and the like. However, hydrophilicity and water resistance have a contradictory relationship with each other; increasing the water resistance will result in a lack of hydrophilicity, making it more likely to stain, and conversely, increasing the hydrophilicity will result in a lack of water resistance, making the image-receiving layer more likely to come off. Become. Therefore, in order to obtain an image-receiving layer having both hydrophilicity and water resistance, for example, in JP-A-57-1791, a mixture of carboxymethyl cellulose and polyamide epichlorohydrin resin was used, or in JP-A-59-135190, a mixture of carboxymethyl cellulose and polyglycidyl was used. It has been proposed to use mixtures with ether compounds as hydrophilic binders. But in this case,
Although it exhibits good fixing properties for oil-based inks and toners from PPC copiers, it has very poor fixing properties for impact printing type printer inks used in word processors, and plate making using this method does not produce clear printed matter. The downside is that you can't get anything at all. In other words, the conventional direct drawing type lithographic printing original plate having both hydrophilicity and water resistance does not have good printer ink fixing properties.

(C) Purpose of the invention The purpose of the present invention is to have both water resistance and hydrophilicity,
The object of the present invention is to provide a direct drawing type lithographic printing original plate having an image-receiving layer that has good fixing properties for oil-based inks and toners of PPC copiers, and also has excellent fixing properties for word processor printer inks. .

(D) Structure of the Invention The lithographic printing original plate of the present invention comprises a mixed pigment of synthetic silica fine powder with a particle size of 20 μm or less and colloidal silica with a particle size of 50 μm or less as an inorganic pigment on a water-resistant support. and an image-receiving layer containing polyvinyl alcohol as a main component as a hydrophilic binder.

The synthetic silica fine powder used in the image-receiving layer is
Conventionally, it has been used as a material with a high degree of hydrophilicity, but when polyvinyl alcohol is used as a hydrophilic binder, there is a problem that sufficient water resistance cannot be obtained and printing cannot be performed. Therefore, JP-A-59
In No.-211052, water resistance was obtained by adding a large amount of modified polyamide resin to polyvinyl alcohol, but the fixability for printer ink was still insufficient. On the other hand, colloidal silica has sometimes been used in place of synthetic fine silica powder, but this has had the problem of improving water resistance but decreasing hydrophilicity. Therefore, in JP-A-60-58895, myo-inositol hexaphosphoric acid and a water-soluble polyvalent metal salt were added to improve the hydrophilicity, but the fixability for printer ink was still insufficient.

As a result of intensive research focused on improving the fixability of printer ink, the inventors of the present invention have found that by using three components, synthetic silica fine powder, colloidal silica, and polyvinyl alcohol, as the main components of the image-receiving layer, sufficient hydrophilicity can be achieved. Provides durability and water resistance,
It has been found that a direct-drawing lithographic printing original plate can be obtained which has excellent fixing properties for PPC toners and oil-based inks as well as excellent fixing properties for printer inks.

Synthetic silica fine powder is a synthetic silica gel obtained by gelling silicic acid, and depending on its formation conditions, it grows from a few microns to 10 microns, and after that, this primary particle becomes extremely porous, which is three-dimensionally connected by chemical bonds. It is silica gel. The synthetic silica fine powder used in the present invention has a size of 20 μm or less with controlled porosity and internal surface area, but there are no particular limitations on the pore diameter or pore volume. In any case, these synthetic silica fine powders are easily available as commercial products.

On the other hand, colloidal silica is generally called silica sol, and is composed of negatively charged spherical silica particles with a particle size of 1 to 100 mμ dispersed in water to form a colloid. Its manufacturing method and physical properties are significantly different from those of the synthetic silica fine powder described above. In the present invention, in addition to the hydrophilic property of colloidal silica itself, colloidal silica particles have the property of firmly adhering to the fine irregularities on the surface of the surrounding material when water evaporates, and the particles also form siloxane bonds with each other. These properties of colloidal silica have made it possible to greatly improve the water resistance of polyvinyl alcohol, which conventionally has been difficult to obtain good water resistance with just a crosslinking agent. The colloidal silica used in the present invention preferably has a particle size of 50 mμ or less. 50
If it is more than mμ, the bond between the colloid particles is weak and sufficient water resistance cannot be obtained, and therefore it is not suitable for the present invention.

Furthermore, if necessary, kaolin clay, titanium oxide, barium sulfate, etc. can be used as inorganic pigments in the image-receiving layer.
Pigments such as aluminum oxide, calcium carbonate, and zinc oxide can be used, but the purpose of the present invention cannot be achieved unless the proportion of the mixed pigment of synthetic silica fine powder and colloidal silica in the inorganic pigment is 30% or more. do not have. If it is less than 30%, the hydrophilicity of the image-receiving layer decreases and background smudges are likely to occur, and the fixability for printer ink is also insufficient. The mixing ratio of synthetic silica fine powder and colloidal silica is 20:
A range of 80-80:20 is good, preferably 40:60-
It is 60:40.

Polyvinyl alcohol is obtained by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, and for the present invention, completely saponified polyvinyl alcohol with a degree of saponification of 90% or more is preferable. Furthermore, a completely saponified product of vinyl acetate-crotonic acid copolymer,
Completely saponified product of vinyl acetate-maleic anhydride copolymer, completely saponified product of vinyl acetate-versatonic acid copolymer, completely saponified product of vinyl acetate-acrylamide copolymer, ethylenic product containing vinyl acetate and silicon in the molecule Modified polyvinyl alcohols such as completely saponified copolymers with unsaturated monomers and acetoacetylated products of completely saponified polyvinyl alcohols can also be used. The amount of polyvinyl alcohol added to the inorganic pigment is 3 to 30 parts per 100 parts of the inorganic pigment; if it exceeds 30 parts, printer ink fixing properties will decrease, and if it is less than 3 parts, the water resistance of the image receiving layer will deteriorate. decreases. Preferably 5
~20 copies.

Further, water-resistant agents such as aldehydes, amines, melamine formaldehyde resins, urea formaldehyde resins, hydrazides, persulfates, or antifoaming agents may be added to the image-receiving layer.

The direct drawing type lithographic printing original plate of the present invention has a structure in which an image-receiving layer is provided on a water-resistant support as described above, and the water-resistant support used here is melamine formaldehyde. High-quality paper that is wet-strengthened using resin, urea formaldehyde resin, polyamide epichlorohydrin resin, etc.
Examples include resin coated paper and plastic film.

In order to make the direct drawing type lithographic printing original plate of the present invention,
A mixed pigment of synthetic silica fine powder with a particle size of 20μ or less as an inorganic pigment and colloidal silica with a particle size of 50μ or less as an inorganic pigment, and an image-receiving layer coating liquid whose main component is polyvinyl alcohol as a hydrophilic binder. It is sufficient to form an image-receiving layer having a coating weight of about 2 to 30 g/m ² by coating it on a support and drying it at 80 to 150°C.

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

The intermediate layer (adhering amount 1 to 20 g/m ² ) may be an emulsion type resin such as acrylic resin, SBR, MBR, NBR, vinyl acetate-ethylene copolymer, or epoxy resin, polyvinyl butyral resin, vinyl acetate resin, or vinyl chloride. Solvent-soluble resins such as resins may be used alone or in combination of two or more. A suitable amount of pigment may also be added to this intermediate layer.

The back coat layer (coating amount: 1 to 20 g/m ² ) may be made of starch or starch derivatives, cellulose derivatives such as carboxymethyl cellulose or hydroxyethyl cellulose, water-soluble materials such as polyvinyl alcohol, casein, vinyl acetate-crotonic acid copolymer, or ammonium polyacrylate. or emulsion type resins such as acrylic resins, SBR, MBR, vinyl acetate-ethylene copolymers, etc. may be used alone or in combination of two or more. Appropriate amounts of pigments may also be added to this backcoat layer.

(E) Examples The present invention will be explained in more detail with examples.

Example 1 An intermediate layer coating solution having the following composition was coated on the surface of a support (100 g/m ² wet reinforced paper) and dried at about 130° C. to form an intermediate layer weighing about 15 g/m ² .

[Intermediate layer coating liquid]

Carboxyl-modified SBR latex (solid content 50%) 120 parts 10% aqueous solution of oxidized starch 100 parts 50% aqueous dispersion of Zeeklite (inorganic pigment manufactured by Zeeklite Chemical Co., Ltd.) 200 parts 80% aqueous solution of melamine formaldehyde resin (Sumitomo) Kagaku Co., Ltd.) 35% aqueous solution of 12 parts curing catalyst (product name: Accelerator)
ACX-P, manufactured by Sumitomo Chemical Co., Ltd.) 2 parts Next, a back coat layer coating solution having the following composition was applied to the back side of this support, and dried at about 130°C to form a back coat layer of about 15 g/ ^m2 . This was subjected to calender treatment to obtain a water-resistant support.

[Back coat layer coating liquid]

SBR latex (solid content 50%) 10 parts 10% aqueous solution of polyvinyl alcohol (product name Poval 117, manufactured by Kuraray Co., Ltd.) 50 parts 50% aqueous dispersion of kaolin 100 parts 80% aqueous solution of melamine formaldehyde resin
2 parts 10% aqueous solution of ammonium chloride 2 parts Water 50 parts Furthermore, an image-receiving layer coating solution having the following composition was coated thereon and dried at about 130° C. to form an image-receiving layer having a weight of about 8 g/m ² .

[Image-receiving layer coating liquid]

Synthetic silica fine powder (trade name Thyroid 308, particle size 7μ, manufactured by Fuji Davison Chemical Co., Ltd.) 40 parts Colloidal silica 20% aqueous dispersion (trade name Snotex C, particle size 10-20μμ, manufactured by Nissan Chemical Co., Ltd.) )
200 parts 50% aqueous dispersion of kaolin clay 40 parts 10% aqueous solution of polyvinyl alcohol (trade name Poval 117, manufactured by Kuraray Co., Ltd.) 120 parts 80% aqueous solution of melamine formaldehyde resin
1.5 parts 10% aqueous solution of ammonium chloride 1.2 parts water 50 parts This original plate for direct drawing type planographic printing was manufactured by Mitsubishi Japanese Word Processor Office Ace 200 (manufactured by Mitsubishi Electric Corporation).
A printing plate was created by directly printing and plate making using a dot printer. This was printed on a lithographic printing machine (Gestettner).
339 (manufactured by Gestettner), more than 500 clear prints with no background smudges were obtained from the beginning. Further, the above original plate was made into a printing plate using a PPC copying machine U-Bix2500MR (manufactured by Konishiroku Co., Ltd.). When this was printed using the above-mentioned printing machine, more than 500 clear prints with no background smudges were obtained from the beginning.

Comparative Example 1 A direct plate lithographic printing original plate was obtained in the same manner as in Example 1 except that the image-receiving layer coating liquid in Example 1 was replaced with the following composition. When this original plate was made into plates using the dot printer of Example 1 and printed using a lithographic printing machine,
The fixation of printer ink was poor and clear printed matter could not be obtained.

[Image-receiving layer coating liquid]

Synthetic silica fine powder (trade name Thyroid 308, particle size 7μ, manufactured by Fuji Davison Chemical Co., Ltd.) 80 parts 50% aqueous dispersion of kaolin clay 40 parts 10% aqueous solution of polyvinyl alcohol (trade name Poval 117, manufactured by Kuraray Co., Ltd.) 30% aqueous solution of 120 parts modified polyamide resin (trade name Epinox P-9007Y, manufactured by Deitz Hercules Co., Ltd.)
50 parts 10% aqueous solution of ammonium chloride 1.2 parts Water 340 parts Comparative Example 2 A direct plate lithographic printing original plate was obtained in the same manner as in Example 1 except that the image-receiving layer coating liquid in Example 1 was replaced with the following composition. When this original plate was made into plates using the dot printer of Example 1 and printed using a lithographic printing machine,
The fixation of the printer ink was poor, and the resulting prints were less clear than the initial ones.

[Image-receiving layer coating liquid]

Colloidal silica 20% aqueous dispersion (trade name Snowtex C, particle size 10-20mμ, manufactured by Nissan Chemical Co., Ltd.)
400 parts 50% aqueous dispersion of kaolin clay 40 parts 10% aqueous solution of polyvinyl alcohol (product name Poval 117, manufactured by Kuraray Co., Ltd.) 500 parts 40% aqueous solution of glyoxal 30 parts 50% aqueous solution of myonositol hexaphosphoric acid 40 parts Cobalt sulfate 2 parts Comparative Example 3 A direct plate lithographic printing original plate was obtained in the same manner as in Example 1 except that the image-receiving layer coating liquid in Example 1 was replaced with the following composition. When this original plate was made into a plate using the dot printer of Example 1 and printed using a lithographic printing machine, the printer ink had poor fixability and only prints that were unclear from the initial stage were obtained.

[Image-receiving layer coating liquid] Synthetic silica fine powder (trade name Thyroid 308, particle size 7μ, manufactured by Fuji Davison Chemical Co., Ltd.) 40 parts Colloidal silica 20% aqueous dispersion (trade name Snotex C, particle size 10-20μ) , manufactured by Nissan Chemical Co., Ltd.)
200 parts 50% aqueous dispersion of kaolin clay 40 parts 10% aqueous solution of carboxymethyl cellulose 150 parts Polyglycidyl ether (trade name: Denacol)
EX920 (manufactured by Nagase Kasei Co., Ltd.) 20 parts water 225 parts Example 2 A direct plate lithographic printing original plate was obtained in the same manner as in Example 1 except that the image-receiving layer coating liquid in Example 1 was replaced with the following composition. When this original plate was made into plates using the dot printer of Example 1 and printed using a lithographic printing machine,
From the beginning, more than 500 clear prints with no background smudges were obtained. Further, when the plate was made using the PPC copying machine of Example 1 and printed using a printing machine, more than 500 clear prints with no background smear were obtained from the beginning.

[Image-receiving layer coating liquid] Synthetic silica fine powder (trade name: Thyroid 978, particle size: 4μ, manufactured by Fuji Davison Chemical Co., Ltd.) 30 parts colloidal silica 20% aqueous dispersion (trade name: Cataloid SI-500, particle size: 7) ~9mμ, manufactured by Catalysts Kasei Co., Ltd.)
150 parts 50% aqueous dispersion of kaolin clay 80 parts 10% aqueous solution of polyvinyl alcohol (trade name Gohsenol N300, manufactured by Nippon Gosei Kagaku Co., Ltd.) 100 parts 80% aqueous solution of melamine formaldehyde resin
1.25 parts 10% aqueous solution of ammonium chloride 1 part water 50 parts (F) Effects of the invention As is clear from the examples, the direct drawing type lithographic printing original plate of the present invention can be used with a word processor printer, a PPC copying machine, etc. Through plate making, it became possible to obtain clear prints without background smudges from the beginning. This greatly contributed to the spread of light printing in offices, and it can be said that the effects of the invention are extremely large.

Claims (1)

[Scope of Claims] 1. A direct-drawing lithographic printing original plate in which an image-receiving layer containing an inorganic pigment and a hydrophilic binder as main components is provided on a water-resistant support, wherein the inorganic pigment has a particle size of
A direct drawing type lithographic printing original plate characterized by using a mixed pigment of synthetic silica fine powder of 20μ or less and colloidal silica with a particle size of 50μ or less, and polyvinyl alcohol as a hydrophilic binder. 2. The direct drawing type lithographic printing original plate according to claim 1, wherein the proportion of the mixed pigment of synthetic silica fine powder and colloidal silica in the inorganic pigment is 30% or more. 3. The original plate for direct drawing type lithographic printing according to claim 1, wherein the mixing ratio of synthetic silica fine powder and colloidal silica is in the range of 20:80 to 80:20.