Polyurethane polymer materials have the advantages of wear resistance, high temperature resistance, good adhesion, convenient construction, etc., but some polyurethane materials have poor waterproof and heat resistance, and need to be modified by specific methods to achieve the purpose of optimization.
As the name implies, waterborne polyurethane uses water as the dispersion medium. With the improvement of relevant environmental protection laws and regulations, waterborne polyurethane has become the focus of the industry. Waterborne polyurethane has been widely used in coatings, adhesives, fabric finishing agents, coating agents and other fields due to its characteristics of non combustibility, high safety and easy modification.
What are the advantages of waterborne polyurethane coatings compared with solvent based polyurethane coatings?
1. The waterborne polyurethane coating does not contain organic solvents, is odorless and pollution-free, and has the advantages of inconsistency and low cost. When using, it can be diluted directly with water, which is convenient to use and easy to clean.
2.The viscosity of waterborne polyurethane did not change obviously with the relative molecular weight of the polymer. It can prepare high molecular weight waterborne polyurethane at low viscosity, which is very beneficial to improve the adhesive strength of the resin. The viscosity of solvent polymer increases exponentially with the increase of relative molecular weight, and gel is easily produced when the molecular weight is large.
3 The viscosity of waterborne polyurethane is generally lower than that of solvent based polyurethane. The smaller the particle size of waterborne polyurethane, the greater the viscosity. The viscosity of solvent based polyurethane increased significantly with the increase of solid content. The viscosity of solvent polymer can be adjusted by controlling the solid content or solvent content, while the viscosity of waterborne polyurethane needs to be adjusted by thickener.
The waterborne polyurethane has good compatibility with various waterborne resins and can be mixed to improve performance or reduce cost. Attention should be paid to the selection of waterborne resin that matches the charging and acid-base properties of ionic waterborne polyurethane, otherwise condensation may occur. Due to the influence of the compatibility between polymers and the solubility of resin in solvent, solvent based polyurethane can not be used with other resins generally.
