MATERIAL OF SILICONE RUBBER COMPOSITION FOR STRUCTURAL GLAZING SEALANT

摘要

PURPOSE:To get high strength, high elongation and sufficient durability even in warm and humid ageing test by using colloidal calcium carbonate as sealing agent, which has a specified BET specific surface area and mean grain diameter. CONSTITUTION:A silicon rubber composition for structural glazing sealant consists of 100wt.% of polyorganosiloxane, whose molecular chain is closed at its end with silanol radical and has viscosity of 500 to 10,000cSt at 25 deg.C; 0.1 to 20wt.% of alkoxysilane and/or its partial hydrolysis condensate shown in a formula I, where R1 and R2 repress monovalent hydrocarbon radicals respectively, and (a) an integer among 0, 1 and 2; 10 to 200wt.% of colloidal calcium carbonate having BET specific surface area of 16.0 to 25.0m2/g and mean grain diameter of 0.05 to 0.20mum and treated on its surface by fatty acid; and 0.01 to 5weight% of hardening promoter. This composition has high strength, high elongation in hardened state and does not deteriorate even after long-term storage in warm water and warm moisture.