| abstract |
WHEN CURED AT ELEVATED TEMPERATURE, SUCH ELASTOMERIC COMPOSITIONS GIVE SILICONE SPONGE RUBBERS HAVING HIGH TENSILE STRENGTH AND AN INTERNAL STRUCTURE OF CONTINUOUS FOAM. THE CURED PRODUCTS CONTAIN NO RESIDUE OF THE CURING AGENT. THUS THEY POSSESS EXCELLENT COMPRESSION SET, RESILIENT ELASTICITY, RESISTANCE TO HEAT, COLD, AND STEAM, ELECTRICAL PROPERTIES AND FLAME RETARDANT PROPERTY. THEY ARE THEREFORE USEFUL AS INSULATING MATERIALS, SOFT PACKING MATERIALS, GASKET CUSHION MATERIALS, TOILET SPONGE PUFFS AND SPONGE FILTERS. (A) FROM 80 TO 99 PARTS BY WEIGHT OF A DIORGANOPOLYSILOXANE GUM HAVING A VISCOSITY OF AT LEAST 1,000,000 CS. AT 25* C., AND CONTAINING FROM 0.025 TO 0.25 MOLE PERCENT OF VINYL-GROUP CONTAINING SILOXANE UNITS IN ITS MOLECULE; (B) FROM 1 TO 20 PARTS BY WEIGHT OF A DIORGANOPOLYSILOXANE HAVING A VISCOSITY OF AT LEAST 10 CS. AT 25* C., AND CONTAINING AT LEAST 10 TIMES AS MANY MOLE PERCENT OF VINYL-GROUP CONTAINING SILOXANE UNITS IN ITS MOLECULE AS IS CONTAINED IN ONE MOLECULE OF COMPONENT (A); (C) AN ORGANOHYDROGEN POLYSILOXANE IN AN AMOUNT SUCH THAT ITS SI-H LINKAGES ARE FROM 50 TO 200 MOLE PERCENT OF THE TOTAL AMOUNT OF VINYL GROUPS CONTAINED IN THE ABOVE-GIVEN COMPONENTS (A) AND (B), AND CONTAINING AT LEAST THREE SI-H LINKAGES IN ITS MOLECULE; (D) FROM 20 TO 100 PARTS BY WEIGHT OF A SILICA FILLER HAVING A SURFACE AREA OF AT LEAST 150 M.2/G; (E) FROM 1 TO 10 PARTS BY WEIGHT OF A BLOWING AGENT; AND (F) A CATALYTIC AMOUNT OF A PLATINUM COMPOUND. THE SILICONE ELASTOMERIC COMPOSITIONS COMPRISE: |