| 摘要 |
Polybutadiene in which at least 80% of the units are present in a cis-1,4 addition structure are made by polymerizing butadiene in the presence of a catalyst system obtained by bringing together (A) a nickel or cobalt compound not containing a halogen directly attached to the metal atom, (B) a tin or gallium chloride, and (C) a lithium alkyl, aryl, or aralkyl, the lithium component (C) only being contacted with the other components of the catalyst system when in the presence of butadiene. Compound (A) may be Ni acetylacetonate, or octoate, or naphthenate, or benzoate, or acetoacetate, or di-isopropylsalicylate, or the corresponding cobalt compounds. Compound (B) may be SnCl4 or GaCl3. The lithium organometallics may be n-butyl, ethyl, phenyl, octyl, sec-butyl, or iso-butyl. The polymerization is preferably effected in a hydrocarbon solvent, and 1-20 parts per million of H2O may be present. The butadiene and solvent may be purified before adding the catalyst components with a portion of (C) just sufficient to remove impurities. The polymers are recovered by pouring the reaction solution into methanol or ethanol. An antioxidant such as 2,6-di-tert.-butyl (p-cresol) may be present.
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