Modified colloidal silicia as performance enhancer of acrylic elastomeric cool roof coatings

 
The use of silane modified colloidal silica in waterborne coatings is well established. Our new study shows enhancement of the over-all performance for acrylic elastomeric coatings. We found an exceptional increase in dirt pick-up resistance for fully formulated coatings for both fresh and aged films; 1000 h in UV chamber. Addition of modified colloidal silica did not affect the total solar reflectance negatively nor caused any coating degradation. Tested formulations met the requirements of ASTM D-6083 for elastomeric coatings. Furthermore, cool roof coatings should not only be highly reflective and stay clean but also be flexible, tough, having good adhesion to withstand the harsh conditions of sun exposure. We unexpectedly found strong improvement in mechanical properties like Young's modulus, strength and adhesion without sacrificing coating flexibility. Surprisingly, in-can stability also improved, especially at high temperature storage of 50°C. A dosage of 8-10 % colloidal silica product appeared to be optimal.