Metal acetylacetonate as a radical initiator and catalyst for polyurethane in dual-curing reaction at low temperature

Abstract

The goal of our research has been to realize dual-curing reaction which is accompanied with radical reaction and urethane reaction at low temperature using a metal acetylacetonate (Mt(acac)x) such as Mn(acac)3, Mn(acac)2, Co(acac)3, Co(acac)2 and Zn(acac)2. To understand radical reaction relationship depending on what kind of metals, Mt(acac)x as a radical initiator is defined by DSC analysis in n-butyl acrylate and EPR spectroscopy. The role of finding TPeak in DSC and g` factor in EPR exhibit Mt(acac)x can generate radical effectively. In order to verify effect of Mt(acac)x in urethane reaction on HFUMO 4039-0 without acryl group and PL-350, real-time storage modulus (G’) was measured by rheometer for curing at 140 °C and checked the initiation temperature (Tinit) and storage modulus (G’). Finally, to evaluate the catalyst the effect of Mt(acac)x as a radical and urethane reaction, rheometer and nanoindenation were constructed with HFUMO 4039-60 with acryl group and PL 350 based on films cured at 140 °C, 120 °C and 100 °C. Considering the initiation temperature (Tinit) and storage modulus (G’) on rheometer and HIT value on nanoindenation, Mn(acac)3 is the best catalyst among tested Mt(acac)x and surface property also maintained despite 100 °C even low curing temperature.