A Review of New Environmentally-Friendly Packaging Printing Varnish (3)

Good film-forming properties, glossiness of coating coating; fast drying of crust; only need a little dusting or no dusting; has very good friction resistance; water resistance, heat resistance, aging resistance, odorless; not yellowing It does not change color; coating coating has high elasticity; coating oil has good slidability; can be washed and water soluble; heat sealing temperature can reach 200°C. It is biodegradable after being discarded, and is an ideal coating oil.
The abrasion resistance of a dispersion-type water-based coating is measured with 50 pressures per square centimeter and can generally reach 150 wipes per minute. Brightness generally can reach 50-70 brightness units, high-grade high gloss paint can exceed 80, sometimes even more than UV bright oil, reaching 90. The drying process of dispersion-type water-based coating varnish is 30% through evaporation, 70% is absorbed by the material and the drying is rapid, and can be completed in a few seconds. When the varnish still contains 20-30% of moisture, it can be filmed, so it does not need to use any drying method. However, if infrared or hot air drying methods are used, the drying speed can be increased. The finished product temperature should not be higher than 30°C and should be stacked at 20-60°C.

The disadvantages are: when using thin paper (approx. 90 g/m2), paper deformation may occur. If light manipulation is performed on both sides, the paper must reach a limited thickness of approximately 135 g/m2 (depending on the material of the paper. Quality); Alkali-resistant inks must be used; it is not easy to remove the dried coating.

3. UV (UV Curing) Varnish

UV (UV Curing) Varnish is a new type of glazing coating that emerged in the late 1980s. The glazing coating is applied on the printing surface, and the internal structure of the coating undergoes a cross-linking reaction by instantaneous irradiation of ultraviolet light, and the coating is immediately generated. Solid and glossy film layer. This kind of photocuring varnish has no solvent volatilization, fast curing speed, high production efficiency, and all weather resistance properties such as gloss and abrasion resistance are superior, and the glazing effect on coated paper and high-grade coating is even Over film effect. The use of high-grade high-quality prints in the use of more and more, in some areas even more than water-based Varnish.

4. Radiation curing varnish with UV

(UV) curing coating and electron beam (EB) coating coating are two types. All of them are low-molecular-weight, high-solid coatings. The hardened film of the glazing film is formed by ultraviolet irradiation or electron beam collision and the drying energy is low. Throughout the curing process, this type of varnish has minimal radioactivity and hardly pollutes the air. Its cured film has a high hardness due to the large degree of cross-linking, and its lightness is also very good.

The solid content in the light coating of the purple needle thread almost accounts for 100%, which consists of a variety of small plastic particles (acrylates) with high activity, photo-initiator, various additives, and reactive diluents. Ultraviolet glazing technology uses short-wavelength excitation of UV light to dry coating coatings. The drying process is a chemical reaction process. In the course of this chemical reaction, atomic groups are generated by the action of photoinitiators and ultraviolet rays, resulting in the incorporation of flavonic acid salts with each other. This process is also called radical chain polymerization.

The advantages of UV coating are: high glossiness of the coating; durability of the coating; fast drying; no powder spraying; high abrasion resistance; no solvent; also suitable for non-absorbent printing materials such as plastics or metal plates.

The disadvantages of UV varnish are: high coating cost, high energy consumption, flammability, health and operational safety, limited product recovery, and inability to post-dry if radiation is insufficient.