There are many types of varnishes, but commonly used varnishes can be roughly classified into three categories: oily varnishes, waterborne varnishes, and UV varnishes. According to the actual application trend of polishing oil and the improvement of environmental protection requirements, the use of oily coating will be reduced. The application space of waterborne coating and UV coating is very broad. The following mainly introduces the waterborne coating and UV. Varnish.

(A) Waterborne Varnish

Water base oil (English called WATERBASE DVARNISH, also known as DISPEERSE DVARNISH), mainly composed of water-soluble resin and water-dispersed resin, water-based polish oil is non-toxic and tasteless, eliminating harm to the human body and Environmental pollution, with fast drying speed, good film transparency, stable performance, wide adaptability of equipment, good abrasion resistance and smoothness on the light-coated surface, wide applicability after printing, good heat sealing performance, safe and reliable use, and storage Convenient transportation and other characteristics, more and more food, medicine, tobacco carton packaging and printing companies pay attention. When UV waterborne varnish is used, the following typical problems should be noted:

(1) How to ensure that the underlying ink can be sufficiently dried after coating the aqueous coating oil, first of all ensure the air permeability of the aqueous coating oil so that the wet ink layer can contact the air and dry the oxidized conjunctiva; otherwise, it can also be improved The hot air temperature makes this problem solved.

(2) The gloss of the waterborne varnish coating is lower than that of the UV varnish. In practice, a small amount of high-boiling solvent can be added to the aqueous varnish to moisturize the emulsion particles to promote the formation of a smooth coating film. Improve the surface smoothness of the coating, and ultimately achieve the purpose of improving the gloss of the waterborne coating.

(B) UV Varnish

UV glazing is a method of curing a glazing coating using UV (abbreviation of Ultraviole, ie, ultraviolet ray) irradiation. It has the characteristics of rapid solidification of coatings and low temperature curing inks that are not easily discolored, which helps to solve many problems in gloss processing of paper prints. Therefore, it has been widely used in the gloss processing of paper containers, trademarks, books, covers, and packaging boxes. application.

UV Varnish is almost solvent-free and emits very little organic volatiles, thus reducing air pollution. UV Varnish does not contain solvents and does not require heat for curing. The energy required for curing is relatively small. In addition, UV varnish has strong affinity for ink and strong adhesion; UV varnish has high active component, less volatilization, and relative saving in dosage; UV varnish has more abrasion resistance, chemical resistance and resistance to the surface of the printed product after curing. Chemical, good stability, able to scrub with water and ethanol; UV glazing products are not easy to adhere, can be stacked after curing, is conducive to post-processing operations.

When using UV varnish, pay attention to the following typical problems:

1UV coating is not suitable for operation on permeable paper. Because the low-molecular materials in the UV coating easily penetrate into the paper, causing the paper to become dark or even saturated. At present, most UV coatings are applied on printed paper with aluminum plating.