| 摘要 |
Sponge rubber is made by dissolving a water soluble gas, e.g carbon dioxide under pressure in a latex or like composition which is stabilized against coagulation by the gas at atmospheric and elevated pressure, reducing the pressure, conveniently to, but not below, atmospheric pressure, whereupon the latex expands to form a foam, and subsequently coagulating the foam. Examples of suitable pressure for charging the latex with carbon dioxide are from 24 to 100 lb. per sq. in., pressures of 40-50 lb. per sq. in. being entirely satisfactory. In an example a latex composition containing saponin as a stabilizer against coagulation by carbon dioxide and calcium sulphate as a heat sensitizer, was treated with carbon dioxide at about 60 lb. pressure per sq. in. with stirring for 2 1/2 hours. The latex was drawn from the container through a suitable valve open to the atmosphere, whereby the issuing latex expanded to a foam which was poured into moulds and vulcanized in steam at 3 lb. gauge pressure for one hour. Other gases, e.g. nitrous oxide may be used. |
