About Novel Silicone Resin Insulating Compounds for Impregnation, Press Forming and Pressure Gelation

Abstract:
Impregnation, lamination and coating are the main application technologies of currently available silicone-resins. Electrical motors, mainly for traction applications, as well as mica-laminates represent the main markets for silicone resin in the field of electrical insulation. Silicone resin compounds for molded parts are not commercially offered in quantities relevant to the market. Driven by the expected outstanding resistance to heat stress and UV-radiation, a novel, solventfree, low viscous silicone resin binder was synthesized. This was then used to develop mechanically reinforced compounds for press forming and pressure gelation applications. The paper deals with the chemical composition and the resulting properties of cured silicone resin compounds. Selected results of the extensive work that was done to evaluate suitable reinforcing fillers as well as first experiences with respect to the processability are presented. Optimization of both, tensile and flexural strength, was achieved by compounding the binder with a special combination of fiber- and particle-shaped fillers. The material shows outstanding thermal stability in comparison to other resinous materials available in the market. The glass transition temperature was measured to be 225 °C, the thermal class is 220 (R).