Improvements in and relating to vulcanizing processes and apparatus for the manufacture of high pressure expanded vulcanized rubber and like substances

摘要

162,176. Marshall, C. L. April 15, 1920. Porous or spongy india-rubber, etc.; vulcanizing-chambers; plastic compositions containing india-rubber and resins, waxes, &c. - In the manufacture of porous expanded india-rubber by vulcanization in an inert gas under high pressure, a wax or resinous substance, such as ceresin is added to the ingredients to minimize the diffusion of gas from the spongy mass. The wax or resin may be omitted from the outer layer, which then gradually loses its gas and forms a resilient skin which prevents excessive expansion of the interior mass. The ingredients are placed in a shell 1 surrounded by an outer vessel 8, which is provided with a heating-jacket 15. Compressed gas is admitted to the vessel 8, and when a certain pressure is attained adjustable automatic valves in the passages 6 admit the gas to the inner shell. Heat is then applied, and temperature and pressure are gradually increased to the maximum values of about 305‹ F. and 75 atmospheres. When vulcanization is complete, the temperature is first somewhat reduced and then the vessel 8 is rapidly exhausted. The automatic valves at 6 retain a pressure of about 100 lb. in the shell 1, which is allowed to remain until the product has cooled and is then released. A mixture of rubber and balata may be substituted for pure rubber if desired, but the proportion of rubber should not be less than onethird.