Development of All Water-Blown Polyisocyanurate Foam System for Metal-Faced Continuous Sandwich Panels

Abstract

Metal-faced sandwich panels have been extensively used as exterior walls in the building industry. Experience and testing have demonstrated that HCFC-141b blown polyisocyanurate (PIR) foams provide acceptable fire performance when incorporated into these types of panel systems. Nowadays, the requirement for the development of all water-blown PIR foam system is getting higher, because HCFC-141b is to be phased out and a waterblown system is environmental-friendly, safe and economical. However, in general, all water-blown PIR foam systems have some problems such as poor flowability, foam friability and poor adhesion strength to metal and paper. Moreover, the poor storage stability of polyol premix of PIR systems due to hydrolysis is a serious issue, since polyester polyol modified PIR foams are generally used to reduce combustability. As for storage stability, the effect of various polyester components and catalysts for PIR foam preparation were examined with respect to the increase of acid value and the change of reaction profile. Through these tests, it was found that the specific combination of polyester components and selected catalysts led to good storage stability of polyol premix. Furthermore, to improve foam properties, a new polyisocyanate was developed. Finally, we developed new all water-blown PIR foam systems which showed similar storage stability to current HCFC-141bsystems: high flowability, less-void appearance, good dimensional stability, good adhesion strength and excellent incombustibility. In this paper, the relationship between each component of PIR foam and various properties will be discussed.