2008 Volume 20 Issue 1 Pages 36-40
Silicone rubber is widely used as tubes in beverage circuit because of its merit of high heat-resistance and food hygiene. The organic peroxide cured silicon rubber has been used for this purpose, however, it has being replaced by the platinum cured rubber in recent years. The vulcanization promoted by organic peroxides inevitably generates debris. The remained debris is necessary to be removed by postcure treatment of 225 oC, 24hrs, which is rather harsh condition for silicone rubber. The vulcanization by platinum catalysts generates no such debris, and hence has been recognized as a promising method to ensure the quality of beverages. However, the relationship between physical properties, in particular, heat resistance capacity and postcure condition was not examined. The present report compares the silicone rubbers prepared by peroxide and platinum vulcanization, with employing various postcure conditions, in physical properties of tensile strength, ultimate elongation, and hardness before and after the themal aging process. Advantage of the platinum cured rubber was evident under the postcure conditions that were settled to ensure their tasteless nature. Moreover, thermal deterioration of the platinum cured rubber was remarkably suppressed using a heat resistance reagent containing several kinds of rare earth metals.
