Abstract: The invention is related to a novel compound represented by NdHA4 wherein A is a carboxylate, and to a diene polymerization catalyst using the novel compound. NdHA4 has monomeric structure and does not contain water, bases and salts. NdHA4 is mixed with a halogen compound and an organic metal compound to prepare a catalyst system. The catalyst system in the polymerization of 1,3-butadiene (BD) or isoprene produces high cis polydiene with a high activity (100 g BD/4.0×10−5 mole Nd) and without gel formation. The polydiene thus obtained is useful for tires and golf balls and as a polystyrene modifier.

Abstract: This invention relates to a process for preparation of high 1,4-cis polybutadiene and more particularly, to the process for preparing polybutadiene by polymerizing 1,3-butadiene monomer in the presence of a catalyst prepared by aging a mixture of a neodymium salt compound, a nickel salt compound, an organoaluminium compound and a borontrifluoride complex compound in the presence or absence of a conjugated diene compound. With much remarked catalytic activity, polybutadiene with a very high 1,4-cis content can be prepared in a high yield using a small amount of catalyst.

Abstract: A method for preparing polybutadiene having controlled molecular weight and high 1,4-cis content over 95% in the presence of a diethylzinc compound as a cocatalyst (i.e., alkylating agent) and molecular-weight-controlling agent, in which the molecular weight of the polybutadiene is controlled by variating the added amount of the diethylzinc compound without deterioration of 1,4-cis content nor polymerization yield, thus guaranteeing the optimum processability and physical properties of polymer according to the use purpose.

Abstract: Disclosed is a process of controlling the degree of branch of high 1,4-cis polybutadiene without any alternation in the 1,4-cis content and the polymerization yield, in which a dialkylzinc compound represented by the following formula I is added in a controlled amount as an agent for controlling the degree of branch of high 1,4-cis polybutadiene, thus guaranteeing the optimum processability and physical properties of polymer according to the use purpose.

Abstract: This invention relates to a process for preparing polybutadiene with high 1,4-cis content (over 97%) and high conversion (over 90%) in such a manner that 1,3-butadiene is polymerized using an aging catalyst, which has high homogeneity due to its excellent solubility in non-polar solvents, resulting in producing polybutadiene having low gel content and low solution viscosity. The aging catalyst is a mixture of a neodymium compound, an organoaluminum compound and a borontrifluoride complex, which is represented by the formula I or the formula II, in the presence or absence of a small portion of conjugated diene compound:Formula I is represented byBF.sub.3 OR.sub.1 R.sub.2wherein R.sub.1 and R.sub.2 can be the same or different, and are independent substituents, respectively which are alkyl, cycloalkyl, allyl, aryl or arylalkyl groups containing from 1 to 10 carbon atoms; andFormula II is represented by ##STR1## wherein R.sub.3 is an alkyl group containing from 2 to 10 carbon atoms.

Abstract: This invention relates to a process for controlling the molecular weight distribution of high 1,4-cis polybutadiene and more particularly, to a process of easily controlling the molecular weight distribution of polybutadiene which is concerned directly with the physical properties such as processability, in such a manner that preparation of high 1,4-cis polybutadiene is made available via polymerization of 1,3-butadiene in the presence of Ziegler-Natta catalyst, adding carboxylic acid represented by following formula I for the controlling of the molecular weight distribution of polybutadiene based on the contents of carboxylic acid, may be easily controlled, without any alternation in the 1,4-cis contents. ##STR1## Wherein R is selected from the group consisting of alkyl, cycloalkyl and arylalkyl groups substituted or unsubstituted with at least one or more halogen atoms, or alkyl, cycloalkyl and arylalkyl groups with at least one or more double bonds containing from 5 to 20 carbon atoms.