Amine-Manganese Complex as an Efficient Catalyst for Polyurethane Syntheses

Abstract

The polyurethane industry has progressed rapidly, and reactions of polyols and isocyanates are wellknown technological processes. The chemical structure of polyurethane is diverse, and as physical properties are discovered, the wide use of polyurethane is spreading accordingly. But there exists a problem: discoloration by air and light. In general, aliphatic isocyanate is used to resolve this problem. However, the reaction rate of aliphatic isocyanates on preparations of polyurethane is very slow compared with aromatic isocyanates. Therefore, tertiary amines1–5 and tin compounds,6–10 having excellent catalytic activity, are used mainly as catalysts for polyurethane formation. In particular, dibutyltin dilaurate (DBTDL) has been used. However, tin is toxic to human beings. Accordingly, a new catalyst or catalytic system is necessary to replace this catalyst. Recently, late transition metal complexes such as metal-β-diketone complexes (Mt(acac)n) are being researched with great interest.11–13 For example, Fe(acac)3 and Cu(acac)2 complexes are used for the reaction between hexamethylene diisocyante (HDI) and alcohols.14, 15 Although there is sufficiently the catalytic activity for only Mt(acac)n complexes, the increase of the catalytic activity is expected by the cocatalyst. The co-catalyst plays important roles in many reactions. On urethane formation reaction, triphenyl bismuth (TPB)-hexafluoroacetylacetonato (f6acac) catalytic system shows high catalytic activity and the existence of the co-catalyst such as f6acac is important to the reaction.16 In the present paper, the activities of Mt(acac)n and tertiary amine-Mt(acac)n catalyst as new group catalytic system are described. The data clearly show that instead of DBTDL, the tertiary amine-Mt(acac)n can be used for catalyst of the reaction between HDI and alcohol. EXPERIMENTAL