Preparation of rigid polyurethane foam catalyzed by Cu-amine and Mn-amine complexes

The complexes of metal-amine [M(en)₂ and M(trien)] and metal-amine-salicylate [M(en)₂Sal₂ and M(trien)Sal₂], where M = Cu and Mn, were synthesized. The metal complexes were used as the catalysts in the preparation of rigid polyurethane foams. The reaction times, physical and mechanical properties of the prepared foams were investigated and compared to the foam prepared by commercial catalyst (N,N-dimethylcyclohexylamine, DMCHA). FTIR, UV-vis spectroscopy, elemental analysis and X-ray diffraction were used to characterize the catalysts. ATR-IR technique was used to determine isocyanate (NCO) conversion and polyisocyanurate:polyurethane (PIR:PUR) ratio in the polyurethane foam. The foaming reaction is an exothermic reaction. The maximum polymerization temperature is in the range of 100-136 °C. During foam preparation, the cream time, gel time, tack free time and rise time were investigated. The results showed that the apparent density of prepared foams was in the range 39.0-50.0 kg/m³. Cu(en)₂ and Cu(trien) catalysts showed better catalytic activity than DMCHA catalyst. Furthermore, the compressive strengths of rigid polyurethane foams catalyzed by Cu(en)₂, Cu(trien) and Cu(trien)Sal₂ were better than that of DMCHA. At NCO index of 100, their compressive strength values were 257.0, 237.7 and 255.2 kPa, respectively. While at NCO index of 150, their compressive strength values were 370.6, 338.5 and 357.3 kPa, respectively.