REACTION INJECTION MOLDING OF POLYUREAS AND URETHANE BASED IPN.

Reaction injection molding (RIM) started with polyurethanes (PU). The materials used for RIM production are mainly urethane elastomers. Urethanes with catalyst are fairly reactive at 40 to 50 degree C, the temperature at which they typically are mixed by impingement. Another approach of PU modification is done by introducing a second reaction system into the urethane reaction to make up the deficiencies of the existing material. This approach is essentially an application of interpenetrating polymer networks (IPNs) to the RIM process. The second reaction system may also modify the processing characteristics of the resin, such as reaction rate, maximum exotherm and resin viscosity. There have been several commercially available urethane based IPN compounds introduced in recent years (4,5). This work discusses the mixing and curing characteristics of a polyurea system and a PU/polyester IPN system in the RIM process.