Varnish, also known as OPV (over print varnish), is a liquid that is coated on the surface of printed materials to increase gloss, abrasion resistance, water resistance and chemical resistance. Varnish includes water-based varnish, oil-based varnish, UV varnish, alcohol-soluble varnish and other varieties.
Polyethylene wax is the most commonly used abrasion resistance additive in the ink industry, and also has properties such as improved handfeel, anti-stick, anti-stick stain, and water resistance. In water-based varnish, polyethylene wax mainly appears in four ways, such as water-based micronized wax, dispersion, microdispersion and wax emulsion.
The main advantage of water based wax is that they do not contain emulsifiers and add less. Their main disadvantage is that the dispersion in aqueous systems requires high technical conditions and the ease of application is poor.
The advantages of wax emulsions and wax dispersions are ease of use, many product specifications, and a wide range of options. The disadvantage is that the matching relationship with the aqueous resin system must be fully considered, and the shelf life of wax emulsions and wax dispersions and the high and low temperature resistance of storage and transportation must be taken into account.
Application of aqueous wax emulsions in aqueous varnishes
The influence of wax on the abrasion resistance and gloss of varnish is very much related to the particle size of wax additives. Wax dispersions with larger particle size have better abrasion resistance, but the matting is also very obvious. The wax emulsion with smaller particle size has good gloss, and the abrasion resistance under the same amount of addition will be poor. The microdispersion of wax is a better balance, which ensures better abrasion resistance without affecting the gloss of water-based varnish.
In order to adapt to the development of water-based gravure printing, some of wax additives products have been optimized for ethanol resistance to meet the customer’s need for fast drying of the coating.
Different particle sizes of wax additives in the water-based ink performance varies greatly, should be selected according to different needs or compounding, different wax additives ethanol resistance performance also varies greatly, the use of the process should also pay attention to the water-based gravure ink manufacturers can also consider not applying water-based flexo board commonly used varieties of wax additives, you can choose to work with wax additives manufacturers, together with the exploration of new systems in the most suitable additives specifications.
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