Analysis on the application of waterborne polyurethane (WPU) in coatings

Waterborne polyurethane is used in water based wood coatings, which is expected to obtain excellent film hardness, heat resistance and dielectric properties, and good film-forming properties. The higher the degree of microphase separation of aqueous polyurethane,the greater the difference of softening temperature, the better the film formation and heat resistance, but for wood coatings, film hardness and resistance to media is also an important measure of the performance of the index. In order to improve the dielectric resistance and the hardness of the coating, it is necessary to increase the crosslinking density and increase the proportion of the rigid segments in the molecular segments, it certainly will reduce the flexibility and relative molecular mass of the waterborne polyurethane molecules. These are not conducive to the micro phase separation, the mixing degree increased,unfavorable to the film.

The research route is of high hardness, low molecular weight (less than 1000) polyester polyurethane preparation to obtain a high degree of crosslinking, heat resistance, chemical resistance and film hardness.  At the same time, with good flexibility, high molecular weight (more than 2000) linear polyester preparation or low branching polyurethane, to improve the degree of microphase separation, the coating has excellent film-forming properties, reduce film-forming agent dosage, improve the film hardness rise velocity. And through these 2 kinds of polyurethane copolymerization to obtain comprehensive performance.

For more information about water based polyurethane wood coating, please feel free to contact sales@sinogracechem.com