Preparation of rigid polyurethane foams using catalysts prepared from metal nitrates and ethylenediamine/triethylenetetramine

Abstract

The development of catalysts for rigid polyurethane (RPUR) foam were investigated. Metal-amine complexes, [M(X)(en)₂ and M(X)(trien) where M = Cu, Ni, Co, Fe and Zn; X = (NO₃)₂, SO4, (Cl)₂, CO₃; en = ethylenediamine and trien = triethylenetetramine], were synthesized and used as catalysts for preparation of RPUR foam. FTIR, UV-Vis spectroscopy, mass spectrometry, atomic absorption spectroscopy and elemental analysis were used to characterize these catalysts. The reaction times of RPUR foams formation and foam appearance were investigated. The results indicated that Cu(NO₃)₂(en)₂ and Cu(NO₃)2(trien) had good catalytic activity when compare with other metal complexes. The catalytic activity of metal-amine complexes and properties of RPUR foams were investigated and compared to those prepared by commercial catalyst, N,N-dimethylcyclohexylamine (DMCHA). RPUR foams with different densities and compressive strength were prepared by varying the amount of catalysts and water which acted as a blowing agent. The optimum formulation of catalyst content and water content were 1 pbw and 3 pbw, respectively. The compressive strength of RPUR foams varying with the density. The higher compressive strength of foam which catalyzed by Cu(NO₃)2(trien) was due to higher foam density when compared with foam that catalyzed by Cu(NO₃)₂(en)₂.