| 摘要 |
A polybutadiene having 1, 4-cis-enchainment which is sulphur-vulcanizable to produce a product which at 20 DEG C. is amorphous when unstretched and shows crystallinity under X-ray examination when stretched and has a stresselongation diagram of a shape similar to that of a vulcanized natural rubber is made by polymerizing butadiene in the presence of a catalyst made by contacting a compound of titanium wherein the titanium is in its maximum valency state and has each of its valencies satisfied by chlorine atoms or three of its valencies satisfied by chlorine atoms and the remaining valency satisfied by an alkoxy group, with an alkyl metallic compound of aluminium, zinc or beryllium, the p said alkyl metallic compound and said compound of titanium being used in a molar ratio of 1 : 1 to 2,5 : 1 and subjecting the polymerization product to solvent fractionation followed by further extraction or dissolution and reprecipitation. In the examples, butadiene is polymerized in the presence of a catalyst made from titanium tetrachloride, and triethyl aluminium, triisobutyl aluminium, trihexyl aluminium or diethyl zinc, the products being extracted successively with acetone, methyl ethyl ketone and diethyl ether, the product being dissolved in diethyl ether, the resultant solution being cooled to precipitate the polymer which is redissolved in ether at room temperature, the solution being cooled to 40 DEG C. and the precipitate separated by decantation, the operation being repeated three or four times to produce a polymer having a 1, 4-cis content of 80%-85%. The polymer obtained being sulphur vulcanized in the presence of zinc oxide, stearic acid and 2, 21-methylene-bis (4-methyl-6-t-butyl phenol). Specification 834,554 is referred to.
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