JPS59192596A - Antioffset coating material for printing ink - Google Patents

Abstract

PURPOSE:To prevent offset of a printing ink from occuring, by providing a coating mateial consisting of specified quantities of cellulose nitrate having a specified degree of nitrification, an ester and an alcohol or a derivative thereof, and the remainder of water. CONSTITUTION:The coating material consists of 5-25wt% of cellulose nitrate having a degree of nitrification of 10.7-12.2, 10-30wt% of an ester, 10-30wt% of an alcohol or a derivative thereof and the remainder of water. The quantity of cellulose nitrate needs to be 5-25wt% from the viewpoint of offsetting preventing performance. The ester has a function of dissolving cellulose nitrate, it may be an acetate such as ethyl acetate, methyl acetate or butyl acetate, and the quantity thereof needs to be 10-30wt%. The quantity of the alcohol needs to be 10-30wt%. The coating material is quickly dried to form a thin uniform film, which can prevent the offset.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating agent for preventing offset of printing ink 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.
It contains resin, mineral oil, etc., and when the printing ink dries, some of the drying oil, mineral oil, and solvent penetrate into the paper, so the resin dispersed in the drying oil, mineral oil, and solvent forms a 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).
Take the process. For this reason, the printing ink requires a long time to dry, and especially when printing paper is stacked, the printing ink does not dry sufficiently, causing set-off and adhesion of the printing paper (prodskink) due to the weight of the printing paper. This was a major hindrance to speeding up printing.

Conventionally, methods such as drainboard removal, spraying of powder such as starch, heating and drying of printed matter, irradiation with radiation such as ultraviolet rays and infrared rays, and application of water-based varnish have been adopted as countermeasures. There are the following problems. The slat removal method, in which a slat is inserted between two pieces of paper to prevent the 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. .

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 forced to dry by heating, but heating and cooling the printed matter requires a huge amount of energy.
There is a problem in terms of energy conservation. Ultraviolet irradiation method (% Kaisho 5
5-108479, JP-A-54-72237, and JP-A-52-152306) require a special ultraviolet curable ink, which is 2 to 3 times more expensive than regular ink. Also, there are problems in practicality, such as requiring an expensive ultraviolet irradiation device. The infrared irradiation method (Japanese Unexamined Patent Publication No. 53-55217) was aimed at non-powder, but currently it is not possible to dry the printed surface in a short time, and the effect is only that the amount of powder sprayed is reduced compared to the conventional method. I can only hope. Furthermore, methods such as microwave irradiation, laser beam irradiation, and electron beam irradiation have many problems in terms of ink cost, equipment cost, and energy consumption, and are therefore impractical.

A water-based varnish for preventing set-off has been proposed as a solution to these drawbacks. The water-based varnish for preventing set-off (Japanese Patent Publication No. 50-14975, Japanese Patent Publication No. 55-41916, Japanese Patent Publication No. 55-41917゜Japanese Patent Publication No. 53-18055) is printed using printing ink, and then the varnish is applied to the printed surface. The purpose is to prevent set-off by coating the printed surface with one or more of acrylic esters and methacrylic esters.

Vinyl monomers such as styrene, acrylonitrile and acrylamide;
Although it is dissolved or dispersed in water or alcohol in the presence of one or more emulsifiers, the aqueous varnish has the following drawbacks.

(1) Varnish is expensive, and in order to achieve the same anti-set-off performance as the spray method, it must cost 5 to 10 times as much as spray powder.

[2] The drying properties are not sufficient, and only a slight effect of preventing set-off can be obtained.

(3) In view of printing quality and cost, it is necessary to apply the coating as thinly as possible, but if the coating is applied to a thickness of 1 μm or less, the coating will break or become grainy, making it impossible to form a uniform coating.

As described above, the 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 has a nitrification degree of 107 to 12.2 and a cellulose nitrate of 5 to 2.
S wt, esters 10~! The present invention relates to a coating agent for preventing set-off of printing ink, consisting of 10 vrt%, 10 to 30 wt% of an alcohol or its derivative, and the balance water.

The present invention will be explained in more detail below.

The cellulose nitrate used in the present invention has a degree of nitrification (nitrogen content % in cellulose nitrate) of 10.7 to 12.2. If the nitrification degree is less than 10.7, the film strength is weak.
When the nitrification degree is 12.2 or more, the blast furnace property increases and the material becomes explosive. The amount of cellulose nitrate added is 5 to 2 for anti-set-off performance.
s wt% is required, preferably 10-20 wt%
It is.

The esters used in the present invention have the ability to dissolve cellulose nitrate, and are ethyl acetate.

Examples include acetate esters such as methyl acetate and butyl acetate. The amount of addition is required to be 10 to 50 wt. 10vr
If it is less than t%, the dissolution of cellulose nitrate is sufficient.
Wttl) or higher, the viscosity and contact angle increase, resulting in poor workability and difficulty in forming a thin film.

The alcohols used in the present invention include monohydric alcohols such as isopropyl alcohol, methanol and ethanol, polyhydric alcohols, and derivatives of polyhydric alcohols such as cellosolve and calpitol. Alcohols are co-solvents for cellulose nitrate, and when used in combination with esters, they have the effect of increasing the solubility of cellulose nitrate. The amount of alcohol added is 10-30
vyt chi is necessary Δ. If it is less than 10 wt%, the drying properties are poor, and if it is more than 30 vrt%, there are safety and hygiene problems.

The coating agent of the present invention described in detail above exhibits an effect of preventing set-off when applied to the surface of printed matter, etc., and has the following advantages compared to the conventional method for preventing set-off, and is industrially useful. be.

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

(2) It is less expensive than conventional water-based varnishes, and costs about 10% less than conventional water-based varnishes.

(3) Since it is possible to suppress set-off and blocking, which have been problems during high-speed printing, 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 negative 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.

Example 1 ゛　　　The final concentration of nitric acid 7-.- is 1.5.1゜.

Ethyl acetate 10 vt1%, isopropyl alcohol 20 vt% to give 20, 25, 30 at%
and water (residue) and stirred and dissolved using a stirrer to prepare an aqueous coating agent.

Next, commercially available offset ink A (yellow), offset ink B (red), offset ink C (indigo) and offset ink D (J6') were applied to coated paper in the order of 20η each.
Printing was performed in overprinting using a printing suitability tester at a coating weight of /100-. Apply the above coating agent on top of this at 10cm/1o.
It was applied in a coating amount of od. This sample was tested for set-off prevention, drying properties, abrasion resistance, workability, printing quality, and film uniformity, and the results are shown in Table 1.

JP-A-59-192596 (4) 0 As is clear from Table 1, the concentration of cellulose nitrate is 5 to 2.
It can be seen that the most excellent properties are exhibited at a concentration of 5 wt, especially 10 to 20 wt.

Examples 2 to 10 Various esters and alcohols shown in Table 2 were mixed with 10 wt% of cellulose nitrate and 6 oz of water in the formulation shown in Table 3.
In addition to wt%, a coating agent was prepared and coated on top of a commercially available offset ink printed in the same manner as in Example 1, and the same test as in Example 1 was conducted, and the results are shown in Table 3.

As is clear from Table 3, it can be seen that all coating agents showed good results.

Examples 11-20 Ethyl acetate, isopropyl alcohol each 5.10,
A coating agent was prepared by mixing and dissolving cellulose nitrate and water to a concentration of 20, 30, and 40 vt, and coated on top of a commercially available offset ink printed in the same manner as in Example 1. The test results are shown in Table 4.

As is clear from Table 4, ethyl acetate 10-30vt%
It turns out that 10 to 30 wt% of isopropyl alcohol is preferable.

Examples 21 to 29 A commercially available offset ink was printed on coated paper using an offset printing machine in the same manner as in Example 1, and after printing, a coating agent shown in Table 5 was applied to a coater of 1.0 using the coater built into the printing machine.
Table 5 shows the results of tests for anti-set-off properties and abrasion resistance by coating with a coating amount of 100% f/m''.

As is clear from Table 5, it can be seen that it has sufficient set-off prevention performance.

The method of application using a coater is schematically shown in Part 1, where 1 is the coater and 2 is the coating agent.

3 is paper, 4 is a paper discharge section, and the coating agent is applied to the printed paper via several q-rules and another several rolls.

As described above in the examples, it is clear that the coating agent of the present invention (d) is excellent in workability, print quality (gloss, etc.), set-off prevention property, abrasion resistance, etc. It can be used as a coating agent to prevent transfer.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a coater for applying a coating agent used in Examples 21 to 29 of the present invention. Sub-Agents 1) Meifuku Agent Ryo Hagiwara - Figure 1

Claims (1)

[Claims] Cellulose nitrate 5-2 S with nitrification degree 107-12.2
A coating agent for preventing set-off of printing ink, comprising 10 to 3 wt% of esters, 10 to 3 wt% of alcohols or derivatives thereof, and the balance being water.