JP2622971B2 - Ink composition for flexographic printing - Google Patents

Description

The present invention relates to an ink composition for letterpress printing, and to improve the stability of the ink on a printing machine while maintaining a practically effective drying speed. A printing ink composition intended to significantly improve, thereby reducing the ink loss due to color change and the washing wastewater of a machine, thereby reducing equipment and labor required for wastewater treatment and contributing to environmental purification. It is an invention concerning.

(B) Prior Art Although the printing ink composition according to the present invention can be adapted to printing on all kinds of paper, a cardboard printing ink having problems in work efficiency and other problems will be described below.

That is, the printing ink is required to satisfy not only light resistance, water resistance, and friction resistance, but also have a high drying speed and a high working efficiency, that is, an improvement in printing efficiency.

Conventionally, flexographic printing of corrugated cardboard uses water-based ink, so the ink dries quickly and has the advantage that it can be directly connected to secondary processing such as box making and punching after printing. On the other hand, water-based ink uses a small amount of ink. When printing is carried out by using, there is a defect that the stability on the machine is lacking and the viscosity changes greatly.

In recent years, in particular, since there are many small-volume productions of various types, the number of color changes in printing has increased, and ink that has adhered to or remains on ink rolls, circulation pipes, ink pumps, ink tanks, etc. in printing presses during the color change. As a result, a large amount of wastewater is generated during the cleaning of the ink, and the wastewater treatment requires enormous costs.

(C) Problems to be Solved by the Invention As described above, conventional printing by water-based ink, such as flexographic printing, has the above-mentioned drawbacks. Easy to evaporate,
There were major drawbacks, such as thickening of the ink, making printing impossible, the need for a large amount of water for cleaning the equipment, and an increase in ink loss.

The present invention eliminates the above-mentioned drawbacks of the conventional water-based ink, such as lack of stability on a printing press, frequent occurrence of ink loss, and an increase in costs due to installation of wastewater facilities, and enables extremely efficient printing of cardboard and the like. In order to provide a new ink composition for use in a new printing mechanism,
As a result of intensive studies, the present invention has been completed.

(D) Means for Solving the Problems The feature of the present invention is to provide a printing machine for liquid ink which shields both ends of an anilox roll and a rubber roll and does not have an ink circulation device, that is, supplies while being shielded. When mixing inks for use in printing presses that can print with only the inks used and can minimize ink consumption and washing wastewater, glycol (95-50%) and water are used as solvents for resins, pigments, additives, etc. (5 to 50%).

That is, a pigment, an antifoaming agent, a wax, and the like are kneaded with a solid styrene-modified maleic resin, a styrene-modified acrylic resin, an acrylic resin, and the like with the solvent in the above-described ratio.

As the glycol, ethylene glycol, diethylene glycol, and propylene glycol are mainly used. A water-based ink has been conventionally used for conventional so-called flexographic printing. However, an ink which uses glycol as a main solvent and contains a large amount of water, such as 5 to 50%, as in the present invention, is not used at all. Printing ink according to the inventor's invention for use in other printing mechanisms having different uses and effects (Japanese Patent Publication No.
No. 62-14190) has a similar composition, but there is no such example yet. It is used in the new printing mechanism, such as maintaining low viscosity by the synergistic action of these glycols, water and resins. The excellent effects of the printing ink composition according to the present invention can be obtained.

(E) Action The printing ink composition according to the present invention comprises a solid styrene-modified acrylic resin, an acrylic resin, a styrene-modified maleic resin, or the like as a main component of a vehicle. By using 5 to 50% of water, the synergistic action of the solid resin, glycol and water prevents thickening of the vehicle and maintains the stability of the ink despite the accelerated drying speed of the ink. It is characterized by the fact that

(F) Example Hereinafter, the configuration of the present invention will be specifically described with reference to examples of the present invention.

Example-1 High Loss X-1216S (1) 10 Joncryl 67 (2) 20 diethylene glycol 64 diethanolamine 6 100 parts The above mixture was dissolved at 160 ° C. in a reaction vessel to prepare Varnish A.

Hyros X-1216S 30 diethylene glycol 64 diethanolamine 6 100 parts The above mixture was dissolved at 170 ° C. to prepare Varnish B.

Using this varnish B, a base ink A was produced on a three-roll mill with the following composition.

Fastogen Green S ... (3) 30 Varnish B 70 100 parts Using Varnish A and Base Ink A, adding water thereto, and using a dissolver stirrer to prepare Ink A according to the following formulation.

Base Ink A 40 Varnish A 20 Ethylene glycol 17 Chemipearl W400 ... (4) 3 Water 20 100 parts The viscosity of Ink A was 300 centivoise and 20 ° C.

(1) Styrene-modified maleic resin manufactured by Seiko Chemical Co., Ltd. (2) Styrene-modified acrylic acid resin manufactured by Johnson Wax Co., Ltd. (3) Shanin green pigment manufactured by Dainippon Ink and Chemicals, Inc. (4) Wax dispersion (solid content 40%) Mitsui Petrochemical Co., Ltd. Using this ink A, Isowa Iron Works, FPS80 flexographic printing machine (as shown below and in the drawing, shielding both ends of an anix roll and a rubber roll and experimenting without using a circulation device at all) It was used for a corrugated cardboard sheet (using 200 g of jute liner) under the conditions of room temperature of 29 ° C and humidity of 82%. The ink film dried in 12 seconds, and both the physical properties of the ink film and printability were good.

Example-2 Joncryl 550 (5) 30 diethylene glycol 64 diethanolamine 6 100 parts The above mixture was dissolved at 160 ° C. in a reaction vessel to prepare Varnish C.

Using the varnish B produced in Example 1, a base ink B was produced using a dyno mill disperser according to the following formulation.

Lionol Blue FG-7300 (6) 30 Varnish B 20 Diethylene glycol 40 Water 10 KM-70 (7) 0.4 100.4 parts Using varnish A and base ink B, add water to the mixture, and use a dissolver stirrer to ink. B was produced.

Base ink B 40 Varnish A 24 Ethylene glycol 17 Chemipearl W-400 3 Water 16 KM-70 0.4 100.4 parts Ink B had a viscosity of 200 centiboise and 20 ° C. However, (5) Styrene-modified acrylic resin manufactured by Johnson Wax Co., Ltd. (6) Shanin blue pigment manufactured by Toyo Ink Co., Ltd. (7) Silicon defoamer
Α-type flexographic printing machine manufactured by Shinko Kikai Co., Ltd. using Ink B manufactured by Shin-Etsu Chemical Co., Ltd. (As shown below and shown in the drawing, both ends of the anilox roll and rubber roll are shielded, and the experiment is performed without using any circulation device.) As a result of printing on a corrugated cardboard sheet (using 200 g of Oyster Pearl), drying was performed in 40 seconds despite the low temperature of room temperature of 4 ° C and low humidity of 58%, and the physical properties of the ink film and printability were good.

In each of the above embodiments, as shown in the drawing, the both ends of the anilox roll and the rubber roll were shielded and the circulation device was not used, that is, the printing was performed with a small amount of ink by a completely new printing mechanism. The printing increased the viscosity of the ink and made printing impossible. However, the inks A and B according to the present invention were able to obtain stable printability without increasing the viscosity even after printing was continued for one hour.

(G) Effects of the Invention The disadvantage of the conventional flexographic ink in the novel printing mechanism, namely, when printing with a small amount of ink, the viscosity change on the printing press is large, the machine is stopped in a short time, and the ink viscosity is adjusted and the plate is adjusted. Work is inefficient, such as the need to remove the ink above. Further, the cleaning property is poor and a large amount of cleaning liquid is required, and a large amount of generated cleaning waste liquid requires many processing steps and costs.

Since the ink of the present invention maintains the balance between the hygroscopicity of glycol and the evaporation of water, the change in viscosity is extremely small in the novel printing mechanism, and stable printing can be performed for a long time even with a small amount of ink. Furthermore, since it has excellent cleaning properties, it can be cleaned with a very small amount of cleaning liquid, and there is an effect that wastewater treatment equipment is unnecessary or treatment steps are omitted, which contributes to cost reduction and work rationalization. In addition, the purpose of the ink of the present invention in a novel printing mechanism is to enable extremely good printing of the gloss and rub resistance of the ink, and to further improve the drying speed (10 to 40 seconds) without any problem in work. Can be achieved.

[Brief description of the drawings]

The drawings show an example of a roll of a printing mechanism using the printing ink composition according to the present invention, wherein (a) is a longitudinal sectional view taken along the line AA, (b) is a plan view, and (c) is a structure of the printing press. The AA longitudinal cross-sectional view is shown. In the figure, 1 ... Rubber roll 2 ... Anilox roll 3 ... Shield plate 4 ... Ink (supplied between 3 and 3 ') 5 ... Plate cylinder 6 ... Plate 7 ... Press cylinder 8 ... Base paper

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeru Komatsu 3-6-23 Ume no Sato, Tondabayashi City, Osaka Prefecture (72) Inventor Akinori Fukui 92-5 Otanicho, Kashihara City, Nara Prefecture (56) References JP-A 49-49 76606 (JP, A) JP-B 62-14190 (JP, B2)

Claims (1)

(57) [Claims] 1. An ink used in a liquid ink printing machine which has both ends of an anilox roll and a rubber roll shielded to prevent ink loss and which is not provided with an ink circulation device. % Glycol and 5
A printing ink composition characterized by using up to 50% of water.