JPS60995A - Coating agent for preventing offsetting of printing ink - Google Patents

Abstract

PURPOSE:To provide the titled inexpensive coating agent having excellent workability, imparting excellent printing quality such as gloss and excellent in anti- offsetting property and anti-wear property, constituted of a specific composition consisting of CMC-Na, alcohols (derivatives), esters and water. CONSTITUTION:1-5pts.wt. of (A) Na-salt of CMC [pref., the viscosity of an aqueous solution is 10-100cps (60 RPM) at 25 deg.C], 3-10pts.wt. of (B) alcohols (e.g., isopropyl alcohol or cellosolve) or derivatives thereof, 3-10pts.wt. of (C) esters (e.g., ethyl acetate) and the remainder of (D) water are compounded to obtain an objective coating agent. EFFECT:Quick-drying property is imparted and a uniform thin film is formed while high speed printing is enabled. Because of a non-powder system, no environmental pollution is generated and there is no adverse affect to the human body.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating agent for preventing printing ink set-off, which has excellent workable film uniformity and is inexpensive.

The present invention relates to a coating agent for printing ink.

Printing inks such as offset sheetfed ink, offset rotary ink, and letterpress ink generally contain drying oil, drying oil, etc. as a vehicle.
Contains resin, mineral oil, etc., and when the printing ink dries, some of the drying oil, mineral oil, and solvent penetrate into the paper, causing the resin dispersed in the drying oil, mineral oil, and solvent to gel on the paper. Furthermore, unsaturated fatty acid esters in the drying oil are gradually oxidized by oxygen in the air, resulting in oxidative polymerization (drying). For this reason, the printing ink requires a long time to dry, and especially when stacked on printing paper, the printing ink is not sufficiently dried, resulting in problems such as set-off and adhesion of the printing paper (prodskink) due to the weight of the printing paper. This caused trouble and became a major obstacle to the regionalization of printing.

Previously, methods such as drainboard removal, spraying powders such as starch, heating and drying of printed matter, irradiation with ultraviolet and infrared radiation, and application of water-based varnish have been adopted as countermeasures, but these methods have not been effective. Their method has the following problems. The 9 method of removing drainboards, in which the drainboard is completely inserted between two sheets of paper to prevent ink from transferring to the paper below due to the paper's own weight, requires a great deal of labor and has the disadvantage that the smoothness of the printing surface is affected. be. -Does the spray method pollute the working environment, reduce the gloss of printed matter, and reduce abrasion resistance? In rotary offset printing, printed matter is forcibly heated and dried, but a huge amount of energy is required to heat and cool the printed matter, which poses a problem in terms of energy conservation. Since the ultraviolet irradiation method (No. 11, published in Japanese Patent Publication Nos. 55-108479, 72237-1980, and 152-306-1983) requires a special UV-curable ink, it is difficult to use conventional ink. 2~
There are problems with practicality, such as the fact that the price is three times higher and an expensive ultraviolet irradiation device is required. The infrared irradiation method (Patent Publication No. 55-55217/1983) was aimed at producing non-powder, but currently it is not possible to dry the printed surface in a short time, and the amount of powder sprayed is reduced compared to the conventional method. I can only expect results. In addition, methods such as microwave irradiation, laser beam irradiation, and particle beam irradiation have many problems in terms of ink cost, equipment cost, and energy consumption, and are not practical. Water-based varnishes for preventing set-off have been proposed. The set-off prevention water-based varnish (Japanese Patent Publication No. 50-54975, Japanese Patent Publication No. 53-18055) is made by applying the varnish to the printed surface to completely cover the printed surface after printing with the printing ink completely bent. The purpose is to prevent set-off, and one or more of acrylic esters and methacrylic esters.

Vinyl monomers such as styrene, acrylonitrile and acrylamide;
This water-based varnish is dissolved or dispersed in water or alcohol in the presence of one or more emulsifiers, but the water-based varnish has the following disadvantages: (1) The varnish is expensive and cannot be used as a spray method. In order to exhibit transfer prevention performance, the price must be 5 to 10 times that of spray powder.

(2) Drying properties are insufficient, and only a slight set-off prevention effect can be obtained.

(3) In terms of printing quality and cost, it is necessary to apply the coating as thinly as possible, but if it is applied to a thickness of 1 μm or less, the coating will break and become powdery, making it impossible to form a uniform coating. Such conventional methods could not sufficiently prevent set-off of printing ink, and therefore could not meet the demands of the era of high-speed printing.

The present invention has been proposed to eliminate the above-mentioned drawbacks and consists of carboxymethylcellulose salts (
The present invention relates to a coating agent for preventing set-off of printing ink, which comprises 1 to 5 parts by weight of CMC (hereinafter abbreviated as CMC), 6 to 10 parts by weight of an alcohol or its derivative, 3 to 10 parts by weight of an ester, and the balance being water.

The present invention will be explained in more detail below. The CMO used in the present invention has an aqueous solution viscosity of 10 to 10 Q.
It is of Cp8. (25℃, 60RPM) 10
If it is less than 100 cps, the viscosity of the coating agent will be low and the coating thickness will be extremely thin. ! + and both cannot exhibit a sufficient set-off prevention effect.

As the alcohol, monohydric alcohols such as isopropyl alcohol, methanol, and ethanol, polyhydric alcohols such as cellosolve and calpitol, or derivatives thereof (for example, butyl cellosolve) are used. Alcohol (1) Lowers the surface tension of the coating agent and improves the wettability between the ink and the coating agent. (2) Improves the adhesion of the coating agent to printing rollers such as rubber rollers and chrome-plated rollers. The amount of alcohol added is 3 to 10 parts. If it is less than 3 parts, it will not exhibit the above effect sufficiently, and if it is more than 10 parts, there will be safety and sheath problems.Esters include ethyl acetate and methyl acetate.

Acetate esters such as butyl acetate are used. Esters (1) impair the compatibility between the ink and the coating agent, making it easier to form a film of the coating agent on the ink (2) By uniformly dispersing CMOf, the collective viscosity N (so-called It has the effect of preventing OMO (mamako) and improving the solubility of OMO in water.

The amount of ester added is 3 to 10 parts, and if it is less than 63 parts, the above effect will not be sufficiently exhibited, and if it is more than 10 parts, there will be safety and hygiene problems.

When the coating agent of the present invention is applied as detailed above,
Compared to the conventional method, it has the following advantages and is advantageous in terms of technology.

(1) It dries quickly, forms a thin, uniform film, and is highly effective in preventing set-off.

(2) Cheaper than conventional water-based varnish, approximately 170
(3) Since set-off and blocking, which are obstacles to high-speed printing, can be suppressed, high-speed printing is possible, and printing efficiency and print quality can be improved.

(4) Since it is a non-powder type, it can eliminate the problems of conventional powder scattering, such as environmental pollution and adverse effects on the human body.

(5) As drying means does not require a large amount of energy such as heating or irradiation with radiation, costs can be reduced.

Example 0M0f was added to 5 parts of ethyl acetate and 5 parts of Improvil alcohol so that the final concentration of OMO was 0.5, 1, 5, and 5.10 parts, and the mixture was uniformly dispersed using a stirrer.

This liquid was added to water (residue) and dissolved in OMO'i water while vigorously stirring with a stirrer to create an aqueous coating agent. Next, offset ink A (yellow) and offset ink B ( 20mt/1o each in the order of crimson), offset ink O (t,) and offset ink D (t^)
Using a printing suitability/testing machine, overprint with a coating amount of oi, and apply the above coating agent f 10 m9/1 on top of this.
The coating amount was 0.006n''.

The coating method using a coater in the following examples is schematically shown in FIG. The coating agent is then applied to the printed paper via several other rolls. Workability and film uniformity for this sample.

Table 1 shows the results of various tests on printing quality, drying properties, set-off prevention properties, and abrasion resistance.
It can be seen that the most excellent properties are exhibited when the amount is 1 to 5 parts.

Each of the above tests was performed using the following methods.

Workability: Workability during application was visually judged. Film uniformity: Same as above. Print quality: Gloss, N color condition, etc. were visually judged.
c.

Judgment was made by the dry two-finger touch method and the evaporation rate (weight loss) measurement method.

O-side 1 determined by set-off prevention and double blocking tester *Abrasion resistance: determined by Gakushin type abrasion tester.

Table 1 Practical films 2 to 10 Various esters and alcohols were added to 5 parts of 0MC and 85 parts of water according to the formulation shown in Table 2 to prepare a coating agent, and coated on the printing ink in the same manner as in Example 1. Table 3
All tests shown below were performed. It can be seen that all coating agents give good results.

Table 2 Examples 11-20 Ethyl acetate and inpropyl alcohol at 1, 3,
A coating agent was prepared by mixing and dissolving CMC and water in a total amount of 5,10.20 parts, and was applied onto the printing ink in the same manner as in Example 1.

The test results are shown in Table 4. 5-10 parts of ethyl acetate, 3-10 parts of inpropyl alcohol! It turned out to be favorable.

Table 4 As mentioned above in the examples, it is clear that the coating agent of the present invention is excellent in workability, print quality (gloss, etc.), set-off prevention property, abrasion resistance, etc., and is superior to printing ink. It can be used as a coating agent for preventing set-off.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a caulk for applying the coating agent used in Examples 21 to 29 of the present invention. Sub-agent 1η Hl Meikoku agent Ryo Hagiwara -

Claims (1)

[Claims] A coating agent for preventing set-off of printing ink, comprising 1 to 5 M parts of a sodium salt of carboxymethyl cellulose, 3 to 10 parts of an alcohol or its rust conductor, 6 to 10 parts of an ester, and the balance being water.