1.Paper-based coating resins have been switched from natural water-based resins such as celluloses to synthetic resin emulsions such as carboxystyrene butadiene emulsions, polyvinyl acetate emulsions, and acrylic emulsions, among which acrylic emulsions have more excellent properties.However, the above resins are still difficult to meet the higher requirements for the development of coated paper.
Water-based polyurethane can be used as a binder resin in paper coating agents to increase paper printing strength.Water-based polyurethane aqueous dispersions are also used to coat special papers to make them resistant to hydrocarbon solvents. For example, it is used on smooth lead paper in the food packaging industry in an amount of 8-10g / ㎡, and has sufficient oil resistance. Abrasion-resistant, bending-resistant and folding-resistant, high-gloss elastic transparent film. This coating film has good water resistance and resistance to aromatic and ester hydrocarbon solvents.Due to their good performance at low temperatures, they can be used in cryogenic packaging.
2.Waterborne polyurethane is also suitable for decorative coatings due to its high gloss, elasticity and good compatibility with pigments.It is used as a coating on the outer surface of packaging paper bags and cartons, not only for decoration, but also to increase strength and improve packaging quality.Wallpapers with water-based polyurethane as the topcoat are waterproof and stain resistant and can be washed with water. Compounding water-based polyurethane with other water-based resins can make paper have good performance.The paper coating contains a large amount of filler. Generally, calcium carbonate, porcelain clay, dispersant, and water are ground into a ball mill tank to a suitable fineness.Add this material and water-retaining agent, defoaming agent, whitening agent, and water-based polyurethane emulsion to the high-speed dispersing machine to disperse uniformly to obtain water-based polyurethane paper coating.