Polybutadiene composition and method for producing same
A polybutadiene composition which enables the achievement of a rubber material that has excellent crack propagation resistance and a method for producing this polybutadiene composition are provided. A polybutadiene composition is produced by a method that comprises a step Y wherein 1,3-butadiene is polymerized in the presence of 1,2-polybutadiene and a lanthanoid catalyst. A polybutadiene composition which contains 1,2-polybutadiene and 1,4-polybutadiene, and which is obtained by polymerizing 1,3-butadiene in the presence of 1,2-polybutadiene and a lanthanoid catalyst.
1. A method for producing a polybutadiene composition comprising 1,2-polybutadiene and 1,4-polybutadiene, the method comprising:
(X) preparing a reaction mixture comprising 1,2-polybutadiene and an organic solvent by a 1,2-polymerization reaction of 1,3-butadiene in the presence of a cobalt-containing catalyst in the organic solvent,
(Y) adding a lanthanoid-containing catalyst to the reaction mixture prepared in (X) comprising 1,2-polybutadiene to polymerize 1,3-butadiene by performing cis-1,4-polymerization of 1,3-butadiene in the presence of 1,2-polybutadiene and a lanthanoid-containing catalyst to produce 1,4-polybutadiene,
wherein the lanthanoid-containing catalyst comprises a lanthanoid compound and an aluminoxane.
2. The method according to claim 1 , further comprising:
terminating a polymerization reaction in (X) by adding an organoaluminum compound to the reaction mixture in (X).
3. The method according to claim 1 , wherein the cobalt-containing catalyst comprises a cobalt compound, a phosphine compound, and an organoaluminum compound.
4. The method according to claim 1 , wherein the 1,2-polybutadiene is 1,2-syndiotactic polybutadiene.
5. The method according to claim 1 , wherein the lanthanoid-containing catalyst further comprises a halogen compound.
6. The method according to claim 1 , wherein in (Y) 1,4-polybutadiene having active ends is produced; and
the method further comprises (Z) reacting the active ends of 1,4-polybutadiene with an alkoxysilane compound.
7. The method according to claim 1 , wherein the polybutadiene composition comprises from 5 to 30 mass % of 1,2-polybutadiene.
8. A crosslinked product produced by crosslinking a rubber composition comprising a polybutadiene composition produced by the method of claim 1 .