Mixing of molten plastic and gas

Abstract

Abstract GAS IS INJECTED INTO A FLOWING STREAM OF MOLTEN PLASTIC TO PROVIDE A MIXTURE CONTAINING AN AMOUNT OF GAS WHICH AT AMBIENT CONDITIONS WOULD CONSTITUTE ABOUT 10% TO ABOUT 98% OF THE VOLUME OF THE MIXTURE. A RELATIVELY THIN, LARGE DIAMETER ANNULAR STREAM OF MOLTEN PLASTIC ADVANCES THROUGH THE MIXING ZONE, THE GAS BEING INJECTED INTO THE MIXTURE THROUGH AT LEAST ONE OF THE GENERALLY CYLINDRICAL WALLS OF THE MIXING ZONE. OF PARTICULAR IMPORTANCE, THE GAS IS INJECTED THROUGH A POROUS WALL HAVING MORE THAN A THOUSAND OPENINGS PPER SQUARE CENTIMETER, SUCH AS AN ULTRA-FINE SINTERED GLASS FIBRE TYPE OF GAS DIFFUSION MEMBER. EACH OF THE WALLS OF THE MIXING ZONE IS DESIRABLY TAPERED, SO THAT THE THICKNESS OF THE MOLTEN CELLULAR PLASTIC EFFUENT IS GREATER THAN THE THICKNESS OF THE ENTERING STREAM. THE MIXTURE ADVANCES THROUGH A LENGTH OF MIXING ZONE WHICH IS FROM ABOUT TEN TO ABOT ONE HUNDRED TIME THE MARGINAL INCREASE IN THICKNESS OF THE STREAM. THE EFFUENT FROM THE MIXING ZONE FLOWS THROUGH A HEATED STABILIZATION ZONE WHICH IS SEVERAL TIMES LONGER THAN THE MIXING ZONE. THE STABILIZED MIXTURE CAN THEN BE RESHAPED FOR FLOWING INTO STREAMS UTILIZING THE MIXTURE OF MOLTEN PLASTIC AND GAS.

Inventors

• 👤 W Greenberg

Bibliographic Details