| 摘要 |
This invention is based upon the discovery of certain anionic initiator systems can be used to initiate the solution polymerization of conjugated diolefin monomers into rubbery polymers having a low vinyl content. For instance, such initiator systems can be used in the copolymerization of styrene and isoprene to produce low vinyl styrene-isoprene rubber having a random distribution of repeat units that are derived from styrene. These initiator systems are comprised of (a) a lithium initiator and (b) a member selected from the group consisting of (1) a sodium alkoxide, (2) a sodium salt of a sulfonic acid, and (3) a sodium salt of a glycol ether. It is important for the initiator system to be free of polar modifiers, such as Lewis bases. The subject invention more specifically discloses an initiator system which is comprised of (a) a lithium initiator and (b) a member selected from the group consisting of (1) a sodium alkoxide, (2) a sodium salt of a sulfonic acid, and (3) a sodium salt of a glycol ether, wherein said initiator system is void of polar modifiers. The present invention also discloses a process for preparing a rubbery polymer having a low vinyl content which comprises: polymerizing at least one diene monomer with a lithium initiator at a temperature which is within the range of about 5° C. to about 180° C. in the presence of a member selected from the group consisting of (1) a sodium alkoxide, (2) a sodium salt of a sulfonic acid, and (3) a sodium salt of a glycol ether, and wherein the process is conducted in the absence of polar modifiers.
|
