GB304207A - Improvements in or relating to the manufacture of artificial rubber - Google Patents

Abstract

304,207. Carpmael, A., (I. G. farbenindustrie Akt.-Ges.). Jan. 15, 1929. [A Specification was laid open to inspection under Sect. 91 of the Acts, Jan. 17, 1929]. Caoutchouc, synthetic.-The coagulation of a synthetic latex is effected by cooling to below 0‹ C., and after thawing the coagulum is separated from the aqueous emulsifying and polymerizing agent. If the latex contains any unpolymerized diolefine, the separation of the coagulum from the aqueous liquid is interfered with in which case the diolefine is removed, for instance by heating, or reduced pressure or by passing through a current of indifferent gas or by rolling the coagulum. In the examples (1) isoprene is emulsified with sodium oleate solution and heated to 60‹ C. for 4 days, after which a latex is formed by adding water, and is then cooled to 150‹ C. for 1¢ hours, the coagulum being easily separated after thawing. (2) isoprene is emulsified with sodium oleate and heated to 60‹ C. for 2 days, the stiff cream being cooled to 20‹ C. for several hours and then thawed; (3) isoprene is emulsified with sodium oleate solution and heated at 35‹ C for 12 hours and the stiff cream is cooled at -2C‹ C. ; the oleate cannot be separated by washing, and the mass is rolled at a moderate temperature, the oleate being separable after the unchanged isoprene has been evaporated; (4) isoprene-sodium oleate emulsion is heated to 60‹ C. for 4 days and cooled to -20‹ C. part of the oleate can be washed out, and, on warming to drive off the isoprene, the rest of the oleate can be removed : (5) isoprene is emulsified with sodium desoxycholate solution, heated to 60‹ C. for 2 days, and cooled to -20‹ C., the unchanged isoprene being then driven off by steam; the emulsifying agent is then washed out. The isoprene expelled can be recovered by condensation.