Process for producing crystalline 1,2-polybutadiene
1,3-Butadiene is polymerized in a hydrocarbon solvent using a catalyst system containing (A) a cobalt salt, (B1) a phosphine compound having one branched aliphatic group of 3 or more carbon atoms or one alicyclic group of 5 or more carbon atoms and two aromatic groups, and (C) an organic aluminum compound, or a catalyst system containing (A) a cobalt salt, (B) (B1) a phosphine compound having one branched aliphatic group of 3 or more carbon atoms or one alicyclic group of 5 or more carbon atoms and two aromatic groups and/or (B2) a triarylphosphine compound having three aromatic groups, (C) an organic aluminum compound and (D) an active halogen-containing compound, thereby obtaining crystalline 1,2-polybutadiene.
1. A process for producing crystalline 1,2-polybutadiene, comprising polymerizing 1,3-butadiene in a hydrocarbon solvent with a catalyst system comprising (A) a cobalt salt, (B1) a phosphine compound having one branched aliphatic group of 3 or more carbon atoms or one alicyclic group of 5 or more carbon atoms and two aromatic groups, and (C) an organic aluminum compound.
2. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein the catalyst system comprises a phosphine complex of a cobalt salt obtained by mixing component (A) and component (B1), and component (C).
3. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein component (A) is at least one selected from the group consisting of cobalt chloride, cobalt bromide, cobalt octylate, cobalt versatate and cobalt naphthenate.
4. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein component (B1) is diphenylcyclohexylphosphine.
5. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein the use ratio of component (B1) to mol of component (A) is from 1 to 5 mol.
6. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein the amount of component (C) is within the range of 500 to 4,000 by the molar ratio of 1,3-butadiene and the aluminum atom in component (C) (1,3-butadiene/Al).
7. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein the hydrocarbon solvent is selected from the group consisting of cyclohexane methylene chloride and mixtures thereof.
8. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein the polymerization temperature is from −20° C. to +120° C.
9. The process for producing crystalline 1,2-polybutadiene according to claim 1 , wherein the crystallinity of the resulting 1,2-polybutadiene is from 5 to 40%.