JPH01133776A - Printing method - Google Patents

Abstract

PURPOSE:To contrive a shorter printing time, higher ink preservability and a lower printing cost, by using an ink not showing tackiness under use conditions of a printed body, adhering the ink to a printing plate under such a temperature condition that the ink is tacky, and transferring the ink onto a body to be printed. CONSTITUTION:At the time of transferring an ink adhered to a printing plate onto a body to be printed, an ink not showing tackiness under use conditions of the printed body is used. The ink is adhered to a printing plate under such a temperature condition that the ink is tacky. Then, the ink adhered to the plate is transferred onto the body to be printed. Where the printed body or the like is to be used at room temperature, the lower limit of the temperature at which the ink is tacky is preferably not more than 50 deg.C. The ink showing such a temperature-dependent tackiness may be, for example, an ink containing a thermoplastic resin and a solvent, or a gel (in a broad sense) comprising a crosslinked substance and a liquid dispersant. The crosslinked substance for the material having a gel state is preferably a natural high molecular weight substance such as guar gum, or a synthetic high molecular weight substance such as polyvinyl alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing method using a printing plate such as letterpress, lithographic, intaglio or stencil.

[Prior Art] Conventionally, printing inks made of drying oils, semi-drying oils, high-boiling solvents, resins, etc. have been used in lithographic offset printing, intaglio printing, and the like.

The drying methods for the ink used in these printing methods include penetrating drying, in which the low-viscosity oil in the ink permeates the paper through capillary action, leaving the ink solids on the paper surface, setting and drying; Oxidative polymerization due to absorption creates a network-structured polymer, causing the ink to lose its fluidity and solidify and dry, or the solvent in the ink.
Evaporative drying, in which solid resin and pigment remain on the printed surface due to water evaporation, is used alone or in combination.

[Problems to be Solved by the Invention] However, when using penetrating drying, it takes several minutes to several hours to dry, especially when printing substrates with non-absorbent surfaces such as aluminum foil, metal plates, and plastic films. However, since set drying by osmosis cannot be used, it requires an extremely long drying time of several hours to more than ten hours.

When using oxidative polymerization drying, the greater the oxidative polymerization drying effect of the ink, the faster the drying and solidification speed of the ink. A reduction in usage speed is required. Further, ink tends to dry and solidify inside an ink tank or the like of a printing machine.

When using evaporative drying, a large amount of space, equipment costs, and energy are required for a thermal drying oven, and if the evaporated solvent pollutes the atmosphere, equipment to treat it is required, which reduces printing costs. There are limits to reduction.゛The present invention was made to solve these problems, and its purpose is to shorten the drying time of the ink even if the surface of the printing medium is non-absorbent, and furthermore, to reduce the printing cost. It is an object of the present invention to provide a printing method in which the ink used has a good shelf life and causes fewer problems in terms of environmental hygiene.

[Means for Solving the Problems] The above-mentioned object of the present invention is to provide a printing method in which ink adhering to a printing plate is transferred to a printing medium, in which the ink does not exhibit tackiness under the conditions in which the printed matter is used. A printing method characterized by using ink and including the steps of applying the ink to the plate under temperature conditions under which the ink exhibits tackiness, and transferring the ink adhered to the plate to the printing medium. It can be achieved.

In the printing method of the present invention, an ink that does not exhibit tackiness under the operating temperature conditions (hereinafter abbreviated as "operating temperature") of printed matter formed by the printing method of the present invention and exhibits tackiness under specific temperature conditions is used. use.

For example, when using an ink that does not exhibit tackiness at room temperature but becomes tacky when heated, heating the ink will slow down the process of adhesion of the ink to the plate and transfer process from the plate to the printing material. can be done. In addition, in the method of the present invention, it is desirable to use an ink that has sufficient adhesion to the printing material after printing. The tackiness and constituent components of such ink will be detailed later.

In the method of the present invention, if printing is carried out while keeping the printing material at the operating temperature in advance, the ink transferred from the plate onto the printing material will not exhibit tackiness. For example, when using an ink that becomes sticky when heated, if you keep the substrate at room temperature and print, the ink will quickly lose its tackiness on the substrate and a special drying method will be used. Good printed matter that is not affected by rubbing or the like can be easily obtained in a short time without using any means or cooling means.

Furthermore, the ink used in the present invention is chemically stable and has a good shelf life, unlike conventional inks that are susceptible to chemical reactions such as oxidative polymerization. Therefore, it is no longer necessary to consider, for example, the time from ink preparation to use for printing, the storage time in an ink tank of a printing machine, etc., depending on the oxidative polymerization rate.

Next, the tackiness of the ink used in the method of the present invention will be explained in detail.

The ink used in the present invention does not show tackiness (non-tackiness)
The state is a state in which the ink is printed with a low level of tackiness that poses no problem in use at the operating temperature, and the degree of low tackiness varies depending on the intended use of the printed matter.

Therefore, the non-adhesiveness of the ink may be appropriately set depending on the intended use. For example, when used at room temperature, it is sufficient that the adhesive exhibits sufficient non-stick properties at around 25°C.

Also, when using ink that becomes sticky when heated,
The temperature at which the ink exhibits adhesion to the plate and the printing material is preferably a temperature that is not too high from the viewpoint of energy efficiency required for heating the ink. For example, when the usage temperature is room temperature, the lower temperature limit at which the ink exhibits tackiness is desirably 80°C or lower, preferably 50°C or lower.

The preferable non-tackiness and tackiness of the ink used in the method of the present invention can be evaluated, for example, by the following method.

(Non-adhesiveness of ink at working temperature) After accurately weighing a piece of aluminum foil of 5cm x 5cm (thickness 0.1mm) on the surface of the ink at working temperature placed in a container, place it gently and leave it at that temperature. The aluminum foil is left in a 60% atmosphere for 1 minute, and then the aluminum foil is gently peeled off from the surface of the fluid ink, and the aluminum foil is quickly and precisely weighed to determine the weight increase of the aluminum foil. It is desirable that the weight increase of the aluminum foil is 10 mg or less, preferably 2 mg or less. It can be evaluated that the ink at that level shows good non-adhesiveness. Note that when the operating temperature is room temperature, the above evaluation method may be performed at a temperature of 25° C., for example.

(Adhesiveness of ink during printing) A method similar to the non-adhesive evaluation method described above was performed using the ink temperature during printing, and the weight increase of the aluminum foil was preferably 20 mg or more, and 50 mg or more. It is preferable. It can be evaluated that an ink with this level of adhesion exhibits good adhesion. Note that when an ink that exhibits tackiness upon heating is used and the operating temperature is room temperature, the above evaluation method at, for example, 50° C. may be performed.

Next, the constituent components of the ink used in the method of the present invention will be explained in detail.

Inks that exhibit temperature-dependent tackiness as described above include, for example, inks containing a thermoplastic resin and a solvent, or gels in a broad sense consisting of a crosslinked structure substance and a liquid dispersion medium. It has relatively low temperatures, so it has good energy efficiency, the liquid component does not easily evaporate, so it has good environmental hygiene and storage stability, and it maintains its adhesion from the plate until it is transferred to the printing material. From the viewpoint of supercooling properties, it is preferable to use a gel in a broad sense consisting of a crosslinked structure material and a liquid dispersion medium.

Examples of crosslinked structural substances for substances having a gel state include guar gum as a natural polymer.

Vegetable sources such as locust bean gum, gum arabic, taragant raginan, pectin, mannan, and starch; microbial sources such as xanthan gum, dextrin, succinoglucan, and curdlan; and animal sources such as gelatin, casein, albumin, and collagen. can be mentioned. Semi-synthetic polymers include cellulose types such as methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose; starch types such as soluble starch, carboxymethyl starch, and methyl starch; alginic acid types such as propylene glycol alginate and alginates; and their geosaccharide types and derivatives. etc. can be mentioned.

Examples of synthetic polymers include vinyl-based polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, carboxyvinyl polymer, and sodium polyacrylate, as well as polyethylene glycol, ethylene oxide, propylene oxide block copolymers, and the like. The above-mentioned materials can be used alone or in an appropriate mixture.

The liquid dispersion medium used in the gel composition together with these polymers is one that does not easily evaporate on printed matter.
Preferable in terms of ink storage stability and environmental hygiene. In terms of evaporation resistance, the vapor pressure at 20°C is 15 mmHg.
or less, preferably lmmHg or less, more preferably 0.
lmmHg or less is used.

Such substances include ethylene glycol, propylene glycol, sorbitol, mannitol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polyhydric alcohols such as glycerin, ethylene glycol monomethyl ether, engineered tylene glycol 1,000 ethyl ether, Examples include glycol ethers such as ethylene glycol motupyl ether, nitrogen-containing compounds such as triethanolamine, formamide dimethylformamide, simethy) resulfoxite, N-methyl-2-pyrrolidone, and 1,3 dimethylimidazolidinone.

As the above-mentioned crosslinked structure material, it is preferable to use a gelatin gel containing 5 to 50% by weight of gelatin, since the temperature at which it exhibits viscosity is relatively low, and it is preferable in terms of printability, supercooling property, etc. In addition, when using the gelatin gel, it is preferable to contain water from the viewpoint of solubility and stability of the ink, and it is preferable to use a mixed solvent of polyhydric alcohol and water as the liquid dispersion medium from the viewpoint of storage stability. But it's preferable.

In addition, the ink used in the method of the present invention contains waxes such as paraffin wax and ester wax, and metal salts of stearic acid such as aluminum stearate, magnesium stearate, and zinc stearate, as adhesion fine-adjusting agents. Metal soaps such as metal salts of fatty acids such as parimitic acid, myristic acid, and lauric acid can be used alone or in an appropriate mixture.

Colorants include inorganic pigments such as titanium oxide, carbon black, and bronze powder used in regular printing inks;
Azo pigments, phthalocyanine pigments.

For dyeing, organic pigments such as lake pigments, and dyes such as acid dyes, basic dyes, oil-soluble dyes, and disperse dyes are used.

By heating the ink described above, conventional letterpress, lithography,
Use printing methods such as intaglio or stencil printing. Various methods can be used to heat the ink, such as heating the ink in advance before adhering it to the plate, keeping the plate at a high temperature and using it as a heat source, or using a combination of these methods. Note that, from the point of view of energy efficiency, it is preferable to partially heat only the contact surface between the plate and the ink, rather than heating all the ink in the ink tank of a normal printing machine.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Ethylene glycol 120 parts by weight (20°C
Water (vapor pressure at 20°C 40 parts by weight 17.5
mmHg) Gelatin 400 parts by weight Trade name
52088, Carbon black manufactured by Nippi Gelatin Industries ■ 6 parts by weight Product name
5TERING R1 Butyl paraoxybenzoate (manufactured by Capot, USA) 1 part by weight (preservative) The above components were mixed while heating to 70°C to prepare an ink.

This ink was coated with a surface area of 25 crrI2 (5 cm x 5 cm) and a thickness of 0.1 in an atmosphere with a temperature of 25°C and a humidity of 60%.
．． mm aluminum foil was gently placed on it, and after leaving it for 1 minute, the aluminum foil was accurately weighed, and the weight increase of the aluminum foil was 1.
It was 0 mg or less.

When the above test was conducted at a temperature of 50°C, the ink adhered to the aluminum foil and the weight increase was 1'70 m.
It was g.

Further, at a temperature of 60°C, the weight increase was 240 mg.

Next, a part of the ink roller on the offset printing machine (Gestit 329FD) was heated to 60°C on the surface with an infrared lamp, and using the above ink heated to 70°C, solid printing was performed with an electrophotographic plate. By doing this, a uniform solid image was obtained on plain paper. The image was a well-fixed image with no show-through.

The ink was left on the printing press at room temperature (23 to 25°C), and printing was carried out 10 days later, and the same peta image as the first one was obtained.

Example 2 Ethylene glycol 1440 parts by weight water
360 parts by weight Butyl paraoxybenzoate 8 parts by weight (preservative) Polyvinyl alcohol 360 parts by weight Nippon Gohsen Kagaku Kogyo ■, trade name Gohsenol GLO3 Carbon black 100 parts by weight (manufactured by Cabot, USA, trade name SR) The above ingredients were heated at 70°C. The ink was created by mixing while heating.

When the above ink was subjected to the same aluminum foil adhesion test as in Example 1, the adhesion amount was 2.
10mg or less at 5℃, 50m at 50℃
It was g.

Further, when solid printing was performed using the above ink in the same manner as in Example 1, good printed matter similar to that in Example 1 was obtained.

Example 3 Reactive dye (manufactured by Nippon Kakami Co., Ltd., trade name Red E-33B) 12 instead of carphone black in Example 1
An ink similar to Example 1 was prepared except that g was used.

When the above ink was subjected to the same aluminum foil adhesion test as in Example 1, the adhesion amount was 2.
10mg or less at 5℃, 230mg at 50℃
It was mg.

Further, when solid printing was performed using the above ink in the same manner as in Example 1, good printed matter similar to that in Example 1 was obtained.

〔Effect of the invention〕

As explained above, according to the printing method of the present invention, since an ink exhibiting temperature-dependent tackiness is used, the printing time is short, the ink has a good shelf life, and there is no need for equipment to treat ink solvents. , printing costs can be reduced.

Claims (1)

[Scope of Claims] 1) A printing method in which ink deposited on a plate is transferred to a printing material, wherein an ink that does not exhibit tackiness under the conditions in which the printed material is used is used as the ink, and the ink is 1. A printing method comprising the steps of: adhering the ink to the printing plate under temperature conditions that exhibit the properties of the ink, and transferring the ink adhering to the printing plate to the printing material. 2) The printing method according to claim 1, wherein the ink exhibits tackiness at a temperature of 50° C. or higher. 3) The printing method according to claim 1 or 2, wherein the ink contains at least a liquid dispersion medium and a crosslinked structure material that holds the liquid dispersion medium. 4) The printing method according to claim 3, wherein the crosslinked structural material is gelatin. 5) The liquid dispersion medium has a vapor pressure of 15 m at 20°C.
The printing method according to claim 3 or 4, wherein the dispersion medium contains 50% by weight or more of a solvent having a temperature of mHg or less. 6) The printing method according to any one of claims 3 to 5, wherein the liquid dispersion medium is a dispersion medium containing a polyhydric alcohol and water. 7) The printing method according to any one of claims 1 to 6, which contains a colorant.