| 摘要 |
<p>1,212,386. Conjugated diene-vinyl aromatic copolymers. MICHELIN & CIE (Compagnie Generale des Establissements Michelin). 19 Feb., 1968 [20 Feb., 1967], No. 8011/68. Heading C3P. Stereoblock copolymers in which one of the blocks has a statistical distribution of monomer units are obtained by copolymerizing a conjugated diene and a vinyl aromatic compound in solution in a hydrocarbon and using a catalyst comprising an organo-lithium compound in two stages, in the former optionally using an aprotic polar compound, and in the latter essentially using 0À5 to 2 moles of hexamethylphosphorotriamide per mole of organo-lithium compound. Specified aprotic polar compounds are hexamethylphosphoramide (used in amounts of less than 0À5 mole per mole of organolithium compound), dioxan tetrahydrofuran, other ethers, and a tertiary amine. The polymers have a higher 1,2- or 3,4-content in the statistical block. The process results in a polymer without terminal polyvinyl aromatic block(s). Further conjugated diene may be added between the two stages. Butadiene and styrene are the specified monomers.</p> |
