JPH021389A - Thermal recording type planographic original plate material - Google Patents

Abstract

PURPOSE:To enhance thermal sensitivity and lipophilicity of a printing area and markedly improve printing quality by providing a specified intermediate layer between a support and a thermal recording layer. CONSTITUTION:An intermediate layer comprising a hollow plastic filler, a heat-fusible substance and a binder is provided between a support and a thermal recording layer to obtain a desired thermal recording type planographic original plate material. When thermal printing on the plate material is conducted by a thermal printer, the heat-fusible substance and the binder in the printed area are melted, so that the printed area on the plate surface becomes highly lipophylic and capable receiving an ink. On the other hand, non-printed areas (non-image areas) are covered by a hydrophilic inorganic pigment, so that a desensitizing treatment after the formation of images enables the resultant plate to be used for printing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a heat-sensitive recording type lithographic printing original plate, and more specifically, the present invention relates to an improvement of a heat-sensitive recording type lithographic printing original plate, which does not require a light source and processing such as development and fixation.
The present invention relates to a thermal recording type lithographic printing original plate that can be easily recorded using a thermal printing device.

[Prior art]

Methods for preparing a lithographic printing original plate include (1) a method of applying inkjet onto a support having a hydrophilic surface (Japanese Patent Application Laid-open Nos. 51-84303 and 1982-6215);

JP-A-56-113-456) (2) A method of plate making by wire tod method or thermal transfer using a support having a hydrophilic surface (JP-A-58-193-154, JP-A-59-7)
6260) (3) Those using an organic photoconductor (JP-A No. 60-239762) (4) Those using a dispersion system of phthalocyanine and zinc oxide (JP-A No. 60-24010)
No. 60) (5) Plate making by discharge destruction (Unexamined Japanese Patent Publication No. 1973)
No. 4-6602, JP-A No. 50-59113, JP-A No. 6
0-194467) (6) A method of removing a hydrophilic layer and a hydrophobic layer with a laser beam (Japanese Patent Application Laid-Open No. 113307-1982) and a method of plate making in heat mode (Japanese Patent Application Laid-open No. 158405-1982)
No.) etc. are known.

However, all of these methods involve various problems and are not industrially satisfactory. for example,
Methods (1) and (2) require the use of special inks and transfer ribbons, and methods (3) and (4) require a cleaning process to make them hydrophilic. In order to utilize the process, a developing (toner) step is also required, which has the drawbacks of high plate-making cost and low sensitivity. Furthermore, the method (5) that uses discharge breakdown causes significant wear on the electrode needles and cannot be considered an industrially advantageous manufacturing method, and the method (6) requires larger equipment and is not suitable for office printing. Not suitable.

By the way, recently, a method using a thermal printing device such as a thermal head has been proposed as a method to overcome the drawbacks of these conventional methods of manufacturing lithographic printing original plates (Japanese Patent Laid-Open No. 58-1
No. 99153, JP-A-59-174395).

These methods are used to prepare a material with a melting point of 60 to 180 on a water-resistant support.
Using a lithographic printing original plate provided with a heat-sensitive recording layer containing a wax, a hydrophilic binder such as polyvinyl alcohol or acetoacetylated polyvinyl alcohol, and a pigment with a particle size of 0.1 to 10 °C, the surface of the heat-sensitive recording layer is thermally heated. An offset printing plate is manufactured by thermal printing with a head, and has the advantage that an offset printing plate can be obtained with a simple device without requiring a light source or developing and fixing as in the past.

However, since this method uses a lithographic printing original plate containing a hydrophilic resin such as polyvinyl alcohol or acetoacetylated boribidyl alcohol in the thermal printing layer, sticking occurs during thermal printing and It is not possible to impart sufficient lipophilicity to the thermal printing layer (recording layer), which causes problems such as low image density and uneven images in printed matter printed with these offset printing plates. However, there was a drawback that clear printed images could not be obtained.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording type lithographic printing original plate that has excellent image density, provides a clear printed image without image unevenness, and has no background smear, and does not cause sticking to a thermal head. .

〔composition〕

According to the present invention, in a heat-sensitive recording type lithographic printing original plate in which a heat-sensitive recording layer mainly composed of an inorganic pigment, a binder, and a heat-melting substance is provided on a support, there is a gap between the support and the heat-sensitive recording layer. Provided is a heat-sensitive recording type lithographic printing original plate, characterized in that an intermediate layer comprising a hollow plastic filler, a heat-melting substance, and a binder is provided.

Since the heat-sensitive recording type lithographic printing original plate of the present invention is provided with the above-mentioned specific intermediate layer between the support and the heat-sensitive recording layer, it provides a good printed image without sticking to the thermal head during thermal printing. Further, when printing using a lithographic printing plate obtained from this product, it is possible to obtain printed matter having excellent image density and resolution, and having a clear printed image without background smearing.

The present invention will be explained in more detail below.

In the present invention, as the hollow plastic filler contained in the intermediate layer, a filler having a thermoplastic resin shell and containing a low boiling point solvent inside is used.

The thermoplastic resin that forms the shell of the plastic microparticles may be polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, polyacrylonitrile, polybutadiene, or a copolymer thereof, such as vinylidene chloride-acrylonitrile. Examples include copolymers. Also, the low boiling point solvent contained within the shell (
As the foaming agent, propane, butane, isobutane, etc. are generally used.

Examples of the plastic filler used in the present invention include ADCA, AlB111, and D manufactured by Nippon Ferrite Co., Ltd.
PT, 0BSH, TSI+ and F-30 manufactured by Matsumoto Yushi Co., Ltd.
Examples include F-50.

As the heat-melting substance, those that melt at 50°C to 200°C are preferably used, and such heat-melting substances include:
For example, carnauba wax, auriculie wax, microcrystalline wax, paraffin wax, ceresin wax, montan wax, candelilla wax, shellac wax, wax wax, beeswax, real wax, low molecular weight polyethylene, fatty acids such as stearic acid, polyethylene glycol Examples include waxes such as stearate.

As the binder, any conventionally known binder may be used, and water-soluble polymer resins and water-dispersible polymer resins are preferably used. In this case, water-soluble polymer resins include, for example, polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, and acrylic acid amide/acrylic acid. Acid ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, Examples include gelatin and casein.

In order to cause a reaction such as a condensation or crosslinking reaction with the resin to make it hydrated, a water-resistant agent such as formaldehyde, glyoxal, chromium alum, melamine, melamine-formaldehyde resin, polyamide resin, polyamide-epichlorohydrin resin, etc. is used. It can also be used.

Examples of water-dispersed resins include unsaturated carboxylic acid resins such as acrylic acid and methacrylic acid, vinyl chloride resins,
SBR, methyl methacrylate-butadiene copolymer, alkyd resin, phenolic resin.

Examples include epoxy resins and ethylene ionomer resins.

The weight ratio of the binder and the hollow plastic filler contained in this intermediate layer is preferably 179 to 9/1, preferably 1/2.

If the usage ratio is less than 179, adhesiveness will decrease and printing durability will deteriorate, and if it exceeds 9/1, thermal sensitivity will decrease and image quality will deteriorate, which is not preferable.

The amount of the heat-fusible substance added is 0.5 to 10% by weight, preferably 3 to 8% by weight, based on the total weight of the intermediate layer. If it is less than 0.5% by weight, the printing density will be insufficient, and if it exceeds 10% by weight, scumming will occur in the printed matter, which is not preferable.

The amount of the intermediate layer attached to the support varies depending on the type of plastic filler, binder, and heat-fusible substance used, but is usually 1 to 15 g/m, preferably 8 to 12 g/m in terms of dry weight.

Inorganic pigments used in the thermal recording J- of the present invention include clay, silica, zinc oxide, titanium oxide, aluminum oxide, calcium carbonate, barium carbonate, barium sulfate, etc. From this point of view, it is preferable to use zinc oxide.

In addition, the binder preferably has a softening point or melting point of 150°C or less by the ring and ball method, and specific examples of such binders include polystyrene, styrene-acrylic ester copolymer, and polyester. -Styrenic resins such as t-butylstyrene, low melting point polyamide resins, polyacrylic esters, acrylic ester/acrylic ester copolymers, polyester resins, ethylene-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymers, Polymer, vinylidene chloride resin, butyral resin, acetal resin,
Examples include polyvinyltoluene, but in order to impart particularly excellent lipophilicity to the plate surface, polystyrene, styrene/acrylic ester copolymer, polyacrylic ester, acrylic ester/acrylic ester copolymer, and It is preferable to use a low melting point polyamide resin.

In the present invention, the binders may be used alone or in combination of two or more.

Further, the heat-melting substance is preferably melted at 50 to 200°C, and examples thereof include carnauba wax, auriculie wax, microcrystalline wax, paraffin wax, ceresin wax, montan wax,
Examples include waxes such as candelilla wax, shellac wax, wax wax, single beeswax, low-volume polyethylene, fatty acids such as stearic acid, and polyethylene glycol stearate.

The appropriate weight ratio of the inorganic pigment and binder used in the present invention is 271 to 10/1, preferably 3/1 to 7/1.

If the usage ratio is less than 271, the hydrophilicity will be insufficient and the background of the printed matter will be easily smudged, and if it exceeds 10/1, the lipophilicity of the printing plate will not be sufficient when thermal printing is performed, resulting in a decrease in image density and image unevenness. This is not desirable because it causes

Further, the amount of the heat-fusible substance used in the present invention is 0.5 to 5% by weight, preferably 1 to 3% by weight based on the total solid content. If it is less than 0.5% by weight, the printing density will be insufficient,
Moreover, if it exceeds 5% by weight, it is not preferable because it causes background stains on printed matter.

Examples of the support used in the present invention include paper, paper moist-strengthened with melamine-formaldehyde resin, urea-formaldehyde resin, etc., synthetic resin film such as polyethylene terephthalate, and metal-deposited paper coated with aluminum or the like. Can be mentioned.

Furthermore, in the present invention, in addition to the above-mentioned essential components, it is also possible to add a dispersion aid for the coating liquid, if necessary. Examples of such dispersion aids include naphthenic acid metal salts, fatty acids and their metal salts, cationic surfactants, nonionic surfactants, anionic surfactants, etc.
The amount added is usually 10% by weight or less based on the solid content of the coating liquid.

The lithographic printing original plate of the present invention can be produced by the following methods, but is not limited to these methods.

First, the above-described plastic filler, binder, and heat-fusible substance are applied to a support, and the coated surface is heated to form an intermediate layer.

Next, a mixture containing an inorganic pigment, a binder, a heat-melting substance, and, if necessary, the above-mentioned dispersion aid is mixed with a heat-sensitive A recording layer coating solution may be prepared, and then coated onto the intermediate layer by a conventionally known method such as a wire bar or roll coater, dried, and calendered if necessary. There are no particular restrictions on the amount of the heat-sensitive recording layer coating liquid applied to the intermediate layer, but it is preferably within the range of 5 g/rn' to 25 g/m.

When the lithographic printing original plate obtained according to the present invention is thermally printed using a thermal printing device such as a thermal printer or a thermal facsimile, the thermally printed area melts the heat-melting substance and the binder, so that the printing plate has excellent adhesive properties. It becomes oily and becomes ink receptive.

On the other hand, the non-printing area (non-image area) is coated with a hydrophilic inorganic pigment, and becomes printable by being desensitized after image formation.

〔effect〕

The heat-sensitive recording type lithographic printing original plate of the present invention has the above-mentioned structure, and has an intermediate layer between the support and the heat-sensitive recording layer, which is composed of a hollow plastic filler, a heat-melting substance, and a binder. In addition to improving thermal sensitivity, the degree of lipophilicity of the printed area also increases, so printing quality can be greatly improved.

[Examples and comparative examples]

Hereinafter, the present invention will be explained in more detail with reference to Examples. All of the sections listed below are based on weight.

Example 1 30 parts of foamable plastic filler (Microsphere F-30, Matsumoto Yushisha jJIJ), 2 parts of polyvinyl alcohol (Kuraray Bobal 117) and S[3R(
Polylac-750, concentration 48%, manufactured by Mitsui Toatsu Chemical Co., Ltd.)
1 part of paraffin wax emulsion (Cellosol 428, concentration 50%, manufactured by Nakatsume Yushi Co., Ltd.) to a coating weight of 3 to 5 g/ra, and heated at 120°C. It was dried for 2 minutes to form an intermediate layer.

Next, a heat-sensitive recording layer coating solution having the following composition was applied onto this intermediate layer using a wire bar so that the coating amount after drying was Log/m, dried at 100°C for 1 minute, and then supercalendered. A lithographic printing original plate of the present invention was obtained.

[Thermosensitive recording layer coating liquid]

Acrylic resin (LR-1551, manufactured by Mitsubishi Rayon Co., Ltd., 4
Zinc oxide and zinc oxide (ZEX #2000 manufactured by Sakai Chemical Co., Ltd.) were added with 2.5% of the total solid content of stearic acid at a weight ratio of 1:4, and diluted with 1 to 1 to 1 toluene to make a 40% liquid.

When the thermal recording type lithographic printing original plate obtained in Example 1 is subjected to thermal printing using a thermal printing device such as a thermal printer or a thermal facsimile, the thermally printed portion melts the heat-melting substance and the binder, so that the plate surface This results in excellent lipophilicity and ink receptivity. On the other hand, the non-printing area (non-image area) is coated with a hydrophilic inorganic pigment, and becomes printable by being desensitized after image formation.

Next, after etching this lithographic printing plate using a normal etching process, printing was performed using a Ricoh auto printer AP1600. More than 1000 prints with images were obtained.

Example 2 A lithographic printing material of the present invention was prepared in the same manner as in Example 1 except that SBR as the intermediate layer forming component was replaced with an acrylic resin (AM-200, concentration 40%, manufactured by Showa Kobunshi Co., Ltd.). I got the original version.

Example 3 The procedure was the same as in Example 1, except that the polyvinyl alcohol as the intermediate layer forming component was replaced with polyvinyl alcohol/glyoxal (Daicel GY-60) = 7/3, and the amount of SBR used was 4 parts. A lithographic printing original plate of the present invention was obtained.

Example 4 The same procedure as in Example 1 was carried out except that in Example 1, Cellosol 428, which is a heat-melting substance as an intermediate layer forming component, was replaced with a polyethylene wax emulsion (Cellosol 774, concentration 34%, manufactured by Nakatsume Yushi Co., Ltd.). A lithographic printing original plate of the present invention was obtained.

Next, when the heat-sensitive recording type lithographic printing original plates obtained in Examples 2 to 4 are thermally printed using a thermal printing device such as a thermal printer or a thermal facsimile, the thermally printed areas are free of heat-fusible substances and binders. Because it melts, it has excellent lipophilic properties on the plate surface, making it receptive to ink. On the other hand, the non-printing area (non-image area) is coated with a hydrophilic inorganic pigment, and becomes printable by being desensitized after image formation.

Next, ■Ricoh auto printer AP-37
When I performed etching printing with 00, the ink receptivity was good from the beginning of printing, and the printed matter was too clear with no background smearing.
I got more than one.

Comparative Example In Example 1, Cellosol-428, which is a heat-melting substance as an intermediate layer forming component, was omitted to obtain a comparative lithographic printing original plate.

When this product was printed using a thermal head in the same manner as in Example 1, a lot of sticking noises were produced. Oil sensitization treatment after printing (
When offset printing was performed after etching, the ink adhesion in the image area was hot and ink transfer was poor, resulting in blurring of the image.

Patent applicant Rico Co., Ltd.

Claims (1)

[Claims] (1) In a heat-sensitive recording type lithographic printing original plate in which a heat-sensitive recording layer mainly composed of an inorganic pigment, a binder, and a heat-melting substance is provided on a support, there is a hollow space between the support and the heat-sensitive recording layer. A heat-sensitive recording type lithographic printing original plate characterized by having an intermediate layer comprising a plastic filler, a heat-melting substance, and a binder.