Polyisocyanate penetration project for OEM 3wet integrated system

 
Within OEM 3wet integrated system, the efficiency of Polyisocyanate (PI) penetration from two component PU clear coat (CC) into base coats (BC) was investigated using different hardeners. The PI penetration into BC layers is well known although it could have only been qualitatively estimated before. But within this study, FT-IR measurements of microtome wedge cuts on the different layers led to quantitative values which proved that low viscosity HDI trimers give more intense PI penetration content compared with standard HDI trimer. The use of low viscosity HDI trimers does not only allow VOC reduction but also give better film appearance (lower WaveScan values) and excellent scratch resistance. Other fundamental properties like Flop index (Al pigment orientation in the BC) and weatherability remained same as standard HDI trimer.