Gummiwerk Kraiburg launches high-temperature resistant silicone
The German company Gummiwerk Kraiburg GmbH & Co. KG now offers high temperature vulcanising (HTV) silicone compounds for use in applications up to 300 °C. According to the manufacturer, the hot-air resistance of standard silicones is about 230 °C.
The base polymer used in these compounds already has outstanding heat resistance properties, which were further optimised, said Gummiwerk Kraiburg. This even allows temporary exposure to temperatures as high as 400 °C without permanent damage to the material. Extensive tests in the temperature range between 225 °C and 300 °C show that the strength properties – depending on the temperature – change only marginally after exposure of up to 2,000 h. The new compounds also feature high resistance to superheated steam. This makes it possible to manufacture seals, for example, with resistance to both heat and steam.
The compounds are suitable for extrusion, pressing and injection moulding processes. Addition crosslinking guarantees generally short cycle times during vulcanisation. However, peroxide crosslinking is also possible, for example, in applications requiring longer vulcanisation. Under normal storage conditions the compounds have a shelf life of at least three months, said the company.
The hardness can be adjusted between 55 and 70 Shore A. After an accurate post-curing process the components are suitable for contact with foods in accordance with the regulations of the German Federal Institute for Risk Assessment (Bundesinstitutes für Risikobewertung – BfR) and the US Food and Drug Administration (FDA).
The low temperature flexibility is as low as –50 °C, which is in the normal range for silicone.