Waterborne Flexographic Printing Inks

In the past 10 years, flexographic printing has developed rapidly, and it is increasingly becoming the first choice for environmentally friendly green printing processes at home and abroad. According to information, there are 6,000 flexographic printing companies in the United States with the most advanced flexographic printing in the world. In 2002, flexographic total output value reached 85 billion US dollars, accounting for 74% in the field of packaging and printing, and accounting for 23% of the entire US printing industry. % is the second largest printing method after offset printing.

The core driving force for the rapid development of flexographic printing is not only the continuous improvement of flexographic technology and equipment, but also the widespread use of green printed materials that meet the requirements of environmental protection, and in particular the universal use of aqueous printing inks and UV printing inks. Here is an introduction to the characteristics and types of these two environmentally friendly inks.

First, flexo ink

Water-based (or water-based) inks are water-based inks. Water-based inks are environmentally friendly inks that are non-toxic, non-polluting and have no residual odor. They are the only non-toxic inks approved by the US Food and Drug Association in all printing inks. Especially suitable for food, beverages, medicines, tobacco and alcohol, children's single toys and daily necessities packaging and other contact with the human body and other sanitary conditions require strict packaging printed matter.

The ink can be diluted arbitrarily with water or ethanol. It can be cleaned with tap water. It is particularly convenient to use, but when printed on the substrate and thoroughly dried, it is insoluble in water and has water resistance.

In recent years, with the advancement of water-based ink binders, pigments, and processing technologies, the quality of water-based inks has been greatly improved, and it has been able to adapt to more sophisticated and sophisticated products. The types of water-based printing inks have become more and more applicable. More and more extensive, it can not only be printed on coated paper, offset paper, whiteboard paper, but also on aluminum foil, gold and silver cardboard, synthetic paper and plastic coated paper, plastic film, self-adhesive paper, corrugated boxes Printed on various printing carriers.
At present, the main varieties of flexo ink are:

(1) High-precision ink: It is suitable for high-grade flexo and gravure printing of paper color fine products, with good printability, high definition, colorful, firm attachment, stable storage and so on.

(2) Polyolefin ink: It is suitable for the printing of PE, PVC, PET, BOPP and other materials with corona treatment on the surface. It is firmly attached, and it is resistant to water, abrasion, and freezing. Its printability is good.

(3) Aluminum foil ink: adapt to aluminum foil, vacuum aluminum-plated paper and gold and silver cardboard printing, strong adhesion, strong water resistance, good printability.

(4) Carton ink: It is suitable for advanced color carton printing, with firm adherence, water resistance and abrasion resistance, and it can be wiped without discoloration. It can be soaked in water for a long time without discoloration.

(5) Water-based gold and silver ink: Suitable for high-grade trademark packaging printing, using imported raw materials processed by anti-oxidation treatment, strong metallic luster, good printing adaptability, supporting the supply of special diluents and additives for various gold and silver inks And color ink.

(6) Clear Ink: Made of dyes or dyes, pigments and mixed color materials, suitable for vacuum aluminum, aluminum foil, silver cardboard, laser paper and other materials printing, can get the effect of similar hot iron, strong metal, color Bright and firm.

(7) Decorative Wallpaper Ink: Applicable wallpaper and other architectural decoration materials and furniture decoration materials, printing, drying fast, no pollution, no residual odor, water resistant, good printability.

(8) Pearlescent ink: adapts to various high-grade trademark printings, with gorgeous color and elegance, strong texture, and firm attachment. In addition to silver and white, there are a variety of colors and rainbow drying pearl ink.

(9) Fluorescent ink: It can adapt to the printing of special trade marks, has certain anti-counterfeiting functions, and is firm in attachment: it has strong water resistance and good printability.

(10) Heat-resisting ink: It is suitable for heat-resistance printing at 180°C～200°C. It can be used for pre-printing in color carton, fast drying, anti-water abrasion resistance, and firm adhesion.

(11) Cork Paper Ink: Suitable for all kinds of environmentally friendly tipping paper printing, non-toxic, odorless, dull, fast drying, strong water resistance, printed paper does not curl.

(12) Waterborne Varnish: Suitable for flexo, gravure and offset on-line glazing, but also can be used for ordinary machine polishing, non-toxic, odorless, fast drying, good gloss, slip wear resistance, adhere firmly, except In addition to the waterborne varnish used on paper, there are aqueous coatings for polyolefin films.

(13) Ink Additives: Common water-based ink additives include ink stabilizers, ink blockers (slow drying agents), ink thinners, ink PH adjusters, ink defoamers, and ink cleaners.

The use of the ink additive can improve the printability of the water-based ink and ensure the smooth progress of the printing process.

Second, flexo UV ink

UV ink is a new type of environmentally friendly ink that uses a certain wavelength of ultraviolet light to undergo a transient photochemical reaction to make a liquid solid. UV inks for flexographic printing are generally relatively thin, with a viscosity range of about 260 CP to 2000 CP (CP is the viscosity unit, translated as centipoise, editor's note), which is much less than the viscosity of offset UV inks.

UV radiation curing products (including UV inks) are praised as “green industry new technologies for the 21st century” for their high efficiency, energy saving, solvent-free emission, environmental pollution, and excellent product performance. Their safety has been recognized by the US Environmental Protection Agency. . According to information, the flexographic printing UV ink used by the United States in 2000 has reached 3,500 tons.

UV ink is not only a solvent-free security ink, but also has many excellent characteristics, such as not easy paste version, high dot definition, bright and bright ink, excellent chemical resistance, dosage and so on. The promotion and application of UV inks will not only be conducive to environmental protection, but will also benefit the improvement of the quality of flexo printing products and promote the further development of flexo printing technology.

The main varieties of flexo UV inks are:

(1) UV paper ink: fast drying and curing, not easy to paste, high definition, bright colors, no light wear, good chemical stability, suitable for printing of color fine products.

(2) UV polyolefin ink: printing on PE, PVC, PET, BOPP plastic film and synthetic paper, etc. that are suitable for surface corona treatment, fast drying, firm adhesion, water resistance, abrasion resistance, and good printability.
(3) UV pearl ink: to adapt to advanced packaging and printing, with pearl luster and metallic luster, gorgeous texture, strong adhesion, good printability, UV pearl ink in addition to silver and white, there are a variety of colors and rainbow interference type and other varieties.

(4) UV transparent ink: made of dyes, dyes, and pigments mixed colors, strong transparency, bright color, strong adhesion, suitable for vacuum aluminum, aluminum foil, silver cardboard, laser paper and other materials printing, you can get similar hot Electrochemical aluminum effect.

(5) UV Varnish: mainly paper UV Varnish, polyolefin film UV Varnish, matt UV Varnish, UV Varnish that can be hot Aluminium, and many other varieties, because of its fast speed, Water-resistant and wear-resistant, it can be glazing on line or stand alone.

(6) UV Auxiliaries: Mainly include living thinners for UV inks, UV curing accelerators, and UV material cleaners. The use of UV additives facilitates easy operation and improves printability.

Source: Painter