Mouldings with multiple hardness zones - produced by injecting into mould differently catalysed filled polyurethane(s) at short intervals from different mixing heads

摘要

Mouldings, and polyurethane RIM mouldings in particular, are produced with zones of different properties, and with differing hardness in particular, using a mould with two or more mixing heads i.e. with two or more metering devices and injecting from them at intervals of 0.1 to 1.5 seconds. Preferred polymers are amine-crosslinked polyurethanes with the same glass-fibre content but different amine contents. ADVANTAGE - The method produces mouldings with little or no visible weld lines between the different zones.