JPS60120762A - Surface coating agent - Google Patents

Abstract

PURPOSE:To provide a surface coating agent which is quick-drying, gives a thin, uniform film and has an offset-inhibiting effect, consisting of Na salt of CMC, an alcohol, an ester, a surfactant and water. CONSTITUTION:3-10pts.wt. Na salt of CMC (an aq. soln. contg. 3-10pts.wt. said Na salt having a viscosity of 1-5P at 25 deg.C and 60rpm) is added to a liquid mixture of 3-10pts.wt. alcohol (e.g. isopropyl alcohol) and 3-10pts.wt. ester (e.g. ethyl acetate) and the mixture is stirred to disperse the Na salt uniformly in the soln. The dispersion is added to water to dissolve the Na salt of CMC. 0.2- 1.0pt.wt. surfactant (e.g. polyoxyethylene alkylaryl ether) is added thereto and the mixture is adjusted so that the whole of the resulting compsn. provides 100pts.wt. EFFECT:Problems of offsetting and the sticking of printing paper in high-speed printing can be eliminated and hence the printing effect and printing quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to surface coating agents, particularly coating agents for printing inks.

Oil-based printing inks such as offset sheet-fed ink, offset rotary ink, and letterpress ink generally contain drying oil, resin, mineral oil, etc. as a vehicle, and drying of the oil-based printing ink involves a portion of the drying oil and mineral oil solvent being contained in the paper. In order to penetrate into the paper, the resin dispersed in the drying oil, mineral oil, and solvent gels and sets on the paper), and the unsaturated fatty acid ester in the drying oil is gradually oxidized by oxygen in the air. It takes a polymerization (drying) process. For this reason, the oil-based printing ink requires a long time to dry, and especially when printing paper is stacked, the oil-based printing ink is not sufficiently dried, causing set-off and adhesion of the printing paper due to the weight of the printing paper. This caused problems such as blocking, and was a major obstacle to speeding up printing.

Conventional countermeasures have been to remove drainboards, spray powders such as starch, heat dry printed materials, and irradiate them with radiation such as ultraviolet and infrared rays. There is a problem. The drainboard removal method, in which a drainboard is inserted between two pieces 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 printed surface is lost. be. On the other hand, the spray method has the problems of contaminating the working environment, reducing the gloss of printed matter, and reducing abrasion resistance. In rotary offset printing, printed matter is forcibly heated;
Cooling requires a huge amount of energy, so in order to save energy,
There's a problem. Ultraviolet irradiation method (JP-A-55-108479
No., Japanese Patent Application Publication No. 1972-'72237, Japanese Patent Application Publication No. 52-15
2306) requires a special ultraviolet curable ink, which has problems in practicality, such as being 2 to 3 times more expensive than ordinary inks and requiring an expensive ultraviolet irradiation device. Infrared irradiation method (Japanese Patent Application Laid-Open No. 55-552
Publication No. 17) was aimed at non-powder, but currently it is not possible to dry the printed surface in a short time.
The only effect that can be expected is that the amount of powder sprayed will be reduced compared to conventional methods. Also, microwave irradiation method, laser light irradiation method,
Methods such as electron beam irradiation also have many problems in terms of ink cost, equipment cost, and energy consumption, and are not practical.

Water-based varnish for preventing set-off has been proposed as a solution to these drawbacks (Japanese Patent Publication No. 50-34975, Japanese Patent Publication No. 55-41916, Japanese Patent Publication No. 55-41917,
(Japanese Unexamined Patent Publication No. 18055/1983). The purpose of the set-off prevention water-based varnish is to prevent set-off by coating the printed surface with the varnish after printing with printing ink. be.

Specifically, at least one of acrylic esters and methacrylic esters, vinyl monomers such as styrene, acrylonitrile, and acrylamide, and organic carboxylic acids such as unsaturated carboxylic acids, acrylic acid, and methacrylic acid are combined with alkali, organic Although the aqueous varnish is dissolved or dispersed in water or alcohol in the presence of at least one of an amine and an emulsifier, the aqueous varnish has the following drawbacks.

(1) Varnish is expensive, and in order to exhibit set-off prevention performance equivalent to that of the spray method, the price must be 5 to 10 times that of the spray method.

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

(3) In terms of printing quality and cost, it is necessary to apply the coating as thinly as possible, but if the coating is applied thinly, the coating may break or become granular, making it difficult to form a uniform coating.

As described above, the conventional methods were unable to sufficiently prevent printing ink set-off, and were therefore unable to meet the demands of the era of high-speed printing.

The present inventors previously disclosed in Japanese Patent Application No. 58-109255, 100 parts by weight of the total, 1 to 5 parts by weight of sodium salt of carboxymethyl cellulose (hereinafter abbreviated as CMC), 6 to 10 parts by weight of alcohol, and ester. Class 6 to 1
We have proposed a coating agent for preventing printing ink set-off, which consists of 0 parts by weight and the balance of water. This coating agent for preventing set-off is slightly lacking in compatibility with printing ink.
When coated on printing ink, there was no problem on a laboratory scale, but in actual printing machines, there were some cases where the coating agent was repelled by the ink and formed into water droplets, and in those areas, the coating agent was coated on top of the ink. Since a film of the agent was not formed, the anti-bleeding performance was also insufficient.

The present invention has been proposed to solve the above-mentioned problems.

That is, the present invention comprises 100 parts by weight of the total, 3 to 10 parts by weight of sodium salt of carboxymethyl cellulose,
Alcohols 3 to 10 parts by weight, esters 6 to 10 parts by weight
The present invention relates to a surface coating agent characterized in that the present invention comprises 0.2 to 1.0 parts by weight of a surfactant and the remainder water.

The OMO used in the present invention has a viscosity of 1 to 5 voids in an aqueous solution of 3 to 10 parts by weight (25°C, 6ORP
M). If it is less than 1 void, the viscosity of the coating agent (surface reversing agent) is low, so the film thickness during application will be extremely thin, and if it is more than 5 voids, a dilute solution will be required for the coating operation, both of which are insufficient. The anti-set-off effect cannot be achieved.

The alcohols used in the present invention include monohydric alcohols such as inglovir alcohol, methanol, and ethanol, polyhydric alcohols such as cellosolve, calpitol, and derivatives thereof. Alcohols (1) lower the surface tension of the coating agent and improve the wettability between the ink and the coating agent, and (2) improve the adhesion of the coating agent to printing rollers such as rubber rollers and chrome-plated rollers. It has the effect of improving things. The amount of alcohol added is from 1 to 10 parts by weight of the coating agent.
0 parts by weight is suitable. If it is less than 5 parts by weight, the above-mentioned effect will not be sufficiently exhibited, and if it is more than 10 parts by weight, there will be safety and hygiene problems.

As the esters used in the present invention, acetic esters such as ethyl acetate, methyl acetate, and butyl acetate are used. Esters have the following functions: (1) improve the compatibility between the ink and the coating agent, making it easier to form a film of the coating agent on the ink, and (2) improve υ, O by uniformly dispersing OMC.
Prevents collective adhesion of MO particles (so-called mamako),
It has the effect of improving the solubility of CMe in water.

Additive edibility of esters, coating agent 100 parts by weight #) 3
to 10 parts by weight is suitable. If the amount is less than 6 parts by weight, the above effects will not be sufficiently exhibited, and if it is more than 10 parts by weight, there will be problems in terms of safety and hygiene.

Further, as the surfactant, polyoxyethylene alkyl allyl ether, polyoxyethylene alkyl ether, sorbitan fatty acid ester, polyoxyethylene alkyl ether sulfate salt, dialkyl sulfosuccinate, etc. are used. The amount of surfactant added varies depending on the type, but it is generally 0.00 parts by weight per 100 parts by weight of the coating agent.
．． A range of 2 to 1.0 parts by weight is preferable. If it is less than 0.1 part by weight, the wettability between the coating agent and the ink will not be improved sufficiently;
If the amount is more than 1 part by weight, there are problems in terms of cost, foaming, strength of the formed film, etc.

The coating agent of the present invention is prepared, for example, as follows. CMO is added to the mixture of alcohol and ester and stirred to uniformly disperse OMO. Next, this liquid was poured into the water being stirred, and after dissolving the CMC in the water,
Add surfactant.

As detailed above, when the coating agent of the present invention is applied, it has the following advantages compared to conventional coating agents, and is extremely useful industrially.

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

(2) It is cheaper than conventional water-based varnishes and costs about 100 yen.

(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 is possible to solve the conventional problems such as environmental pollution due to powder scattering and adverse effects on the human body.

(5) Since a large amount of energy such as heating or radiation irradiation is not required as a drying means, costs can be reduced.

(6) It has good on-machine stability and does not easily stick on the printing press, so it has excellent operability and maintainability, and is easy for operators to use.

It goes without saying that the coating agent of the present invention can form a sakaki membrane not only on the surface of printed matter but also on the back surface of spears on wood, paper, glass, ceramics, and metals. Nor.

Examples of the present invention are shown below. During implementation flJ, “part”
are all parts by weight.

Example 1 The final concentration of cMc in the coating agent was 10
0 parts by weight each 1.2.3.5.7.10°12
．． 15 parts of OMO was added to 6 parts of ingropyl alcohol and 115 parts of ethyl acetate, and the OMO was uniformly dispersed using a stirrer. This dispersion was added to stirring water and stirred vigorously to dissolve CMC in water. In this solution, 0 dialkylsulfoconophosphoric acid is added as surface activity 1.
．． An aqueous coating agent was prepared by adding 1 to 2.0 parts.

Next, offset ink A (yellow), offset ink B (red), offset ink C (indigo), and offset ink D (black) were applied to coated paper in the order of 201 g/100-
It was printed using a printing suitability tester using overprinting with a coating amount of . On top of this, the above-mentioned coating agent was applied at a rate of 10 mg/100-20%, and the anti-bleeding properties, drying properties, workability, seal quality, and wettability with ink (film-forming properties) were tested. The results are shown in Table 1. As is clear from Table 1, 0
The best properties were shown when M0 was 3 to 10 parts and the surfactant was 0.2 to 1.0 parts.

Examples 2 to 8 Seven types of surfactants were mixed with CM 0 according to the formulation shown in Table 2.
A coating agent was prepared by adding 5 parts of Inglobil alcohol (Ko-PA), and 6 parts of ethyl acetate, and it was applied on coated paper coated with printing ink in the same manner as in Example 1, and the test was carried out in the same manner. I did it. The results are shown in Table 3. As is clear from the results in Table 5, all coating agents had good ink wettability and other properties.

As described above in the examples, the coating agent of the present invention has excellent ink wettability (film-forming properties), workability, print quality (gloss, etc.), set-off prevention property, abrasion resistance, etc. It is clear that it is used as a coating agent to prevent printing ink from running off.

Note that the test methods shown in Tables 1 to 3 are as follows.

Workability: Workability during application was visually judged.

Print quality: Gloss, coloring, etc. were visually judged.

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

Judgment was made using a Niblocking tester to prevent set-off.

Abrasion resistance: 1, determined by a Gakushin type abrasion tester Table 2 Table 3

Claims (1)

[Claims] 100 parts by weight in total, 3 to 10 parts by weight of sodium salt of carboxymethyl cellulose, 6 to 1 part by weight of alcohol
0 parts by weight, 3 to 10 parts by weight of esters, surfactant o
, 2 to 1. A surface wave & agent characterized in that the amount of Oi and the remainder are water.