Water-based varnish is a liquid with water as the carrier, coated offline with a printing machine inline or varnishing machine, used to increase the gloss, water resistance and abrasion resistance of paper printed materials. Water-based varnish (or dispersion varnish) is colorless, tasteless, no organic volatiles, low cost, wide range of material sources, good gloss, folding resistance, wear resistance and chemical resistance, economic and hygienic, etc. It is widely used in the printing and packaging of various commodities, including food, drugs, playing cards, cigarettes, children’s toys and other special commodities.
1. Water-based varnish performance is more excellent than oil-based varnish characteristics
The biggest characteristic of water-based varnish is that the varnished product water-based varnish has no taste and odor effect on the goods after varnishing the surface film fast, high smoothness, strong abrasion resistance, no yellowing, good elasticity of the varnish film, high gloss, but also has moisture-proof, waterproof, oil-proof, etc., character performance is far more than oil-soluble varnish.
2. Water-based varnish viscosity problem
Water-based varnish reference dilution viscosity is 20%, excessive dilution will reduce the gloss and wear resistance. If you have special requirements for viscosity, you can contact with the varnish manufacturer to provide specific viscosity products.
Water-based varnish factory viscosity in 35-80 seconds (25 ℃, “coated – 4 cups” measurement), the printing factory can be diluted according to actual needs. Dilution method has a greater impact on the comprehensive performance of the varnish.
Water-based varnish used diluent is generally 1:1 alcohol water solution (i.e. alcohol and water mixed at 1:1), when the proportion of alcohol is high, the drying time is faster; when the proportion of water is high, the drying time is slower. Printers should make appropriate adjustments according to the situation of their own printing presses.
3. The problem of water-based varnish brightness.
Water-based varnish used in food, drugs, playing cards, tobacco, children’s toys and other printing packaging, packaging brightness can not meet the requirements, so you can appropriately increase the amount of water-based varnish in the addition of brightener, water-based varnish increased to the system in order to achieve the brightness requirements.
4. During the production, varnish may also encounter
(1) Residual odor is too large
Reason: 1. the light oil is not completely dry; 2. the drying channel is too short, the odor is too late to evaporate; 3. the light oil itself problems
Add water-based wax emulsion in the production process of water-based varnish, which can be used in the paint to improve the water resistance of the paint film and resistance to heat and back stickiness, anti-scratch, and increase the smoothness of the paint film feel.
(2) Bad abrasion resistance
Reason: 1. too much dilution; 2. too little abrasion resistance; 3. poor abrasion resistance of varnish itself
Add high density polyethylene wax emulsion in the production process of water-based varnish to give water-based varnish high abrasion and scuff resistance. And has a high matting effect.
In packaging printing and commercial printing, etc., in recent years has gradually increased many health, environmental protection, labor protection and other requirements and constraints, especially for food packaging printing requirements are more stringent, the only way to meet the requirements of international health standards. Water-soluble varnish is a new type of printing varnish materials developed by developed countries in recent years, and is increasingly valued by people in the printing industry.
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