| 摘要 |
1276821 Rubber powders DUNLOP HOLDINGS Ltd 1 Jan 1970 [8 Jan 1969] 56/70 Headings C3E C3P and C3Q A spray of an aqueous dispersion or solution of a rubbery polymer is dried and the resulting powdered particles are immediately cooled to a temperature below the glass-transition temperature of the rubbery polymer. The dispersion or solution may be spray-dried, the powdered particles being collected in a cooled chamber e.g. one containing liquid nitrogen. Alternatively, the dispersion or solution is sprayed directly into a cooled chamber and the resulting powder is freeze dried. The powders produced are stored in (solid) CO 2 -ethanol baths. In examples, natural rubber and styrene-butadiene rubber latices are powdered, vulcanizing agents and, in some cases, carbon black being incorporated in the latex before drying or mixed with the rubber powder at - 72‹ C. |
