Study On The Application Of Waterborne Two Component Polyurethane Construction Coating

Acrylic emulsion based construction coatings (commonly known as emulsion paint) has been widely used for exterior, interior wall coating, for its excellent weather resistance, alkali resistance and scrub resistance. However, acrylic resin has thermoplastic characteristics. As a result, the obtained coating's solvent resistance and abrasion resistance cannot meet the high end requirements, such as walls and floor, which limit its applications. After years of development, water borne two component polyurethane (WB 2K PU) coating has become a hot research field in coatings, which was prepared through the combination of high-performance of solvent borne polyurethane (SB 2K PU) and low VOC of water borne coatings. This paper will focus on developing high-performance WB 2K PU coatings by using commercial polyols and hydrophilic modified polyisocyanates.Firstly, the formulations of WB 2K PU coating were studied. Then, the dispersibility of two types of hydrophilic modified polyisocyanate was tested and the effects on the performance of water borne two component polyurethane were invetigated; the film performance of WB 2K PU was analyzed on NCO/OH values, which showed that the NCO/OH = 1.5 ~ 1.8 was optimized. Both PH value and viscosity were analyzed in mixed WB 2K PU, which illustrated the best PH ratio range was around 7.5~8.0; the effects of hydroxyl values on the film properties were investigated. The influence of components on bubbles free film thickness was tested. Moreover, retention ration of the active matter used in anti-mold agent and artificial weathering resistance were studied. The results proved that 2K WB PU had excellent durability. Infrared spectroscopy (IR) of WB 2K PU film was carried out, which shows excessive isocyanate would react with water, the basic chemical reactions lasted for 7 days.