Liquid Silicone Rubber Foams Made with Water as Blowing Agent

Liquid silicone rubber (LSR) is primarily used in injection molding. Foamed molded parts made of LSR are almost nonexistent because the process reliability of LSR foam injection molding is currently not given. It makes sense to have suitable foaming processes for this material as well, because the density of this elastomer is about 1.15 g cm⁻³. With the injection molding process presented herein for foaming LSR, density reductions of up to 40% can be achieved. In this process, up to 3% by weight of water is added to the material. In addition, the hardness of the component changes, it becomes softer. Especially in the case of hardness, the process parameter mold temperature has a decisive influence, as it determines the pore size in the component. Herein, the structural properties of the silicone foam are now discussed as a function of the process parameters and additives for foaming. Thus, with the new process, material can be saved, the haptic properties of components can be changed, and a stable processing method for foamed components made of LSR is found.