| 摘要 |
1,257,042. Extruding polyisobutylene. BADISCHE ANILIN- & SODA-FABRIK A.G. 25 April, 1969 [27 April, 1968], No. 21161/69. Heading B5A. [Also in Divisions B1-B2 and C3] A screw extruder comprises a barrel 8 and a screw 7 rotatable in the barrel, the screw 7 comprising a series of alternating threaded and unthreaded sections in zones 1a, 1b, 2a, 2b, 3a, 3b, the distance between the section in zone 1b and the barrel being from 1¢-4 times the distance between the section in zone 2b and the barrel, and the diameter of the section in zone 3b being less than that of the section in zone 2b. The barrel may be provided with heating and cooling zones (not shown) and a degassing zone 5. The screw may be provided with threaded sections in zones 4, 6 before andafter the threaded section in the degassing zone. An extruder head 10 including a die is located at the end of the barrel. Material to be degraded, e.g. high M.W. polyisobutylene, is fed into the barrel from hopper 9. The profile of the unthreaded section in zone 1b may be frusto-conical as shown or cylindrical. |
