Process for preparing a polymer using lithium initiator prepared by in

Abstract

A process for preparing a polymer comprises polymerizing a conjugated diene monomer and/or a vinylaromatic hydrocarbon monomer in a hydrocarbon solvent in the presence of or in the absence of a randomizer by using a lithium polymerization initiator which is formed by bringing an organolithium compound and at least one secondary amine compound into contact with each other in the polymerization system in the presence of at least said monomer, wherein the polymerization conversion at the time of contact is less than 5%. The secondary amine is an amine compound having two hydrocarbon groups bonded to N or an imine compound in which an NH group and a saturated or unsaturated cyclic structure group form a cyclic structure. The cyclic structure group comprises a hydrocarbon group as the ring member and may also comprise N or O. The method of production uses the initiator which does not require separate preparation of the initiator, shows excellent reproducibility, allows for the evaluation of accuracy of concentration and realizes high effective initiator concentration. The high molecular weight polymer produced by the method has a narrow molecular weight distribution; is controllable; has a highly reproducible molecular weight and microstructure; exhibits excellent coupling properties based on the living polymerization and provides low hysteresis loss properties.