JPS6123665A - High-speed letter press rotary press printing ink having improved frictional resistance - Google Patents

Abstract

PURPOSE:To provide the titled ink which has excellent printability, transferrability and resistance to offsetting and friction and is suitable for use as ink for newsprint, consisting of a mineral oil, a fatty acid and a mineral oil-soluble resin. CONSTITUTION:35-75wt% mineral oil (e.g. machine oil), 5-15wt% fatty acid (e.g. palmitic acid) and 15-35wt% mineral oil-soluble resin (e.g. rosin-modified phenolic resin) are mixed together, and the mixture is heated at 180 deg.C or above to dissolve them homogeneously. The resulting varnish is kneaded with 5- 15wt% pigment (e.g. carbon black) in a roll mill or ball mill. EFFECT:A high-speed letterpress rotary press printing ink which causes neither setoff nor remainder on a guide roller and gives a film having a high strength, can be obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing high-speed letterpress rotary printing ink such as newspaper ink, and more specifically, it relates to printability, ink transferability, set-off resistance and This invention relates to a high-speed letterpress rotary printing ink with excellent abrasion resistance, particularly a printing ink suitable for newspaper ink.

(Prior Art) Broadly speaking, there are two types of newspaper printing methods: high-speed letterpress rotary printing and high-speed lithographic rotary printing. In recent years, an increasing number of companies are converting to the lithographic printing method as a measure to increase the quality of newspaper printed matter, and this method now accounts for about 30% of all rotary presses.

The paper features of this lithographic printing method include sharp characters and beautiful photographic gradation, as well as the fact that the ink on the paper does not stick to hands, that is, the dry ink film has excellent abrasion resistance. This is its biggest advantage.

For this reason, even in the high-speed letterpress rotary printing system, there has been a demand for a newspaper ink that forms a highly abrasion-resistant dry film that does not stain the hands even when the ink on the printed paper comes into contact with the hands.

However, newspaper ink for rotary letterpress printing machines has a
Since the printing ink has a low viscosity of ~10 poise, 70~80% of the printing ink raw material must be mineral oil of 05~10 poise, and even if a few percent of resin phenol is added, it will not form a film. The effect on strength was insufficient.

(Problem to be solved by the invention) The composition of ordinary letterpress newspaper ink is carbon black 10~
12%, complementary colorant 4%, resins 5-8%, mineral oils 81-8%
76%, totaling 100%. Since the drying method of the newspaper printing method depends on the penetrating drying method, mineral oil with good permeability is mainly used as the vehicle for newspaper ink, and non-permeable film-forming components are extremely thin as described above. Only a small amount is used.

For this reason, most of the ink vehicle after printing on paper permeates into the paper, and almost no components necessary for fixing carbon and carbon black to the paper surface remain on the paper. As a result, newspaper printed matter has an extremely weak film strength that easily stains when touched.

Therefore, in order to increase the strength of the film, it is necessary to increase the amount of non-penetrating components that should fix carbon black.

Non-penetrating ingredients include resins and vegetable oils of the drying oil type. In the case of a vehicle using these three, the film strength will be strong, but (1) the viscosity of the ink will be 10 poise or more, so the transferability of the ink will decrease due to poor printability or paper peeling, or , At the stage when the transferred ink film forms a dry film on the paper, a sudden increase in tackiness occurs, and the printed matter rubs on the guide roller or former paper during the process of being transferred to the cutting paper in the folding machine. , troubles such as partial pressure ink on white paper set-off occurred.

Therefore, in order to solve these problems, the present inventors
We believe that even high-solid type phenos have a low viscosity, and after being transferred to paper, they instantaneously solidify and become non-adhesive due to the penetration of the solvent. As a result of various studies on phenos that are compatible with solidification properties, we have arrived at the present invention.

(Means for Solving the Problems) That is, the present invention has succeeded in solving the above problems by using a pheno consisting of mineral oil, a fatty acid, and a resin soluble in mineral oil. As a result, we have completed a rotary letterpress printing ink suitable as a newspaper ink that has no set-off or guide roller residue and has an extremely high film strength.

Examples of the mineral oil used in the present invention include machine oil, spindle oil, and high viscosity mineral oil, which are commonly used as solvents for newspaper ink.

Examples of the fatty acids used in the present invention include myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linoleic acid obtained by hydrolyzing linseed oil, soybean oil, tung oil, safflower oil, coconut oil, and other fats and oils. acid,
Typical examples include higher fatty acids such as arachidic acid.

As the resin soluble in mineral oil used in the present invention, many of those commonly used as lithographic ink and letterpress ink resins are suitable, and such resins include, for example, rosin-modified phenolic resin, maleic acid resin, Examples include petroleum resins and alkyd resins.

K, which produces the printing ink of the present invention, first produces pheno by heating the mineral oil, fatty acid, and resin described above preferably to 180° C. or higher to uniformly dissolve them.

Next, carbon black is usually added as a pigment to this pheno, and if necessary, the above-mentioned mineral oil, resin, and various auxiliaries are also added, and after these are mixed uniformly, a roll mill method, a ball mill method, an attritor method, a sand mill method, etc. It may be kneaded using. After kneading, the ink may be adjusted to the same viscosity and flow rate using the same method as for high-speed letterpress rotary printing ink.

The preferred composition of the ink of the present invention produced by the method described above is 35 to 75% by weight of mineral oil, 5 to 1% of fatty acid.
5% by weight, 15-65% resin soluble in mineral oil,
The pigment content is 5-15% by weight.

(Effects of the Invention) As is clear from the above, the printing ink of the present invention has the following unique effects.

(11) Particularly excellent as a newspaper ink for high-speed rotary letterpress printing.

(2) Forms a highly abrasion-resistant dry film that will not stain your hands even if you touch the surface of the printed paper.

(3) Excellent printability, no deterioration in ink transfer properties due to paper peeling, etc., and no rubbing on guide rollers or former paper during the process of printing paper being cut into paper by a folding machine. Ink does not set off on blank areas.

Hereinafter, the present invention will be specifically explained with reference to Examples. "Parts" in the examples represent "parts by weight."

Example 1 (Varnish A) Rosin modified phenolic resin 44.0 (parts) Soybean oil fatty acid 18.0 Spindle oil
Varnish A having a viscosity (falling ball viscometer) of 1200 voids was produced by mixing the above components at 250° C. according to a conventional method.

Carbon black 1o, o (parts)'1 Miloripur-05 FES A 46.0 Alkyd resin 8.0 (parts) Spindle oil
360 The above ingredients were milled in a ball mill to produce an ink.

This ink had a viscosity (B-type viscometer 6ORPM) of Z9 voids and a glass plate flow rate of 96 in 10 minutes, and exhibited rheological properties equivalent to conventional black ink for newspaper letterpress rotary printing machines. .

When this ink was used to print on newsprint using a plunger type rotary letterpress printing press, normal printing was achieved with no set-off or guide roller residue. The film strength was evaluated using the following method, and as shown below, it was found to be much stronger than conventional products.

O film strength evaluation method: The surface of the printed matter is rubbed with 70 to 9 pieces of high-quality paper at a load of 100 and Ii' 7 cm', and the ink density on the rubbed high-quality paper is measured. The smaller the numerical value, the greater the film strength.Conventional product---0,14 Inventive product---
-0.09 Example 2 (Varnish B) Petroleum resin 54.0 (parts) Linseed oil fatty acid 24.0 Spindle oil
The above components were mixed at 200° C. according to a conventional method to prepare an ink having a viscosity (falling ball viscometer) of 1000 voids.

Carbon black 10.0 (parts) Miloripur-0.5 Varnish B 46.0 Alkyd resin 60 Spindle oil 38.0 The above components were kneaded in a ball mill to produce an ink.

This ink had a viscosity (B-type viscometer 6ORPM) of 7.5 voids and a glass plate flow rate of 90 mm at 10 minutes.

When this ink was used to print on newsprint using a Giless type letterpress rotary printing press, normal printing was achieved with no residue left on the set-off guide roller.

Furthermore, when the film strength was evaluated using the same method as in Example 1, it was found to be 0.085 compared to 0.135 for the conventional product, which was much better than the conventional product.

Claims (1)

[Scope of Claims] 1. A high-speed letterpress rotary printing ink with improved abrasion resistance, characterized by containing mineral oil, a fatty acid, and a resin soluble in mineral oil. 2. The ink according to claim 1, comprising 35-75% mineral oil, 5-15% fatty acid, 15-35% resin soluble in mineral oil, and 5-15% pigment.