GAS-ASSISTED REACTION INJECTION MOULDING (G-RIM) OF POLYURETHANES - NEW DEVELOPMENTS

For some time the development of the Gas-assisted-Reaction Injection Molding (G-RIM) technique, which is expected to combine the process- specific benefits of the gas injection technique and the outstanding material potential of polyurethanes (PU), has been the subject of ongoing research activities at IKV. In this paper further investigations into the moulding process are presented, with the aim of evaluating the feasibility of the G-RIM process for industrial use. Therefore two PU formulations with reaction kinetics similar to those encountered in practice are used. One of these is a minimally crosslinking, segmenting PU elastomer (compact), while the other investigation is focused on the process behaviour of a compact casting PU system that undergoes pronounced crosslinking. It was seen that segmenting, flexible polyurethanes with their lower crosslinking density, and the resultant pronounced or less pronounced thermoplastic phase that results from this during curing, have a greater processing window than is the case for systems that undergo pronounced crosslinking. Moreover it is shown in first trials that even moulding of complex shaped parts - a media duct for example - is possible.