A kind of long chain branched high cis polyisoprene and preparation method thereof

Abstract

The invention relates to long-chain branched high-cis-polyisoprene and a preparation method thereof, and in particular relates to long-chain branched high-cis-polyisoprene with a high branching factor and a preparation method thereof, wherein long-chain branched high-cis-polyisoprene with a high branching factor is prepared via a reaction carried out between linear high-cis-polyisoprene and a bifunctional or polyfunctional organic compound in the presence of a free radical initiator. According to the preparation method, long-chain branched high-cis-polyisoprene with a branching factor of 0.40 to 0.99 is prepared. Thus, the molecular chain degradability of long-chain branched high-cis-polyisoprene is greatly improved; the strain crystallization ability and tensile strength of long-chain branched high-cis-polyisoprene are obviously enhanced; and the heat stability, elongation at break, tearing strength, hardness, wet-skid resistance and other performance indexes of long-chain branched high-cis-polyisoprene are even superior to those of natural rubber.

Description

Technical field: [0001] The invention relates to a long-chain branched high-cis-polyisoprene and a preparation method thereof, specifically, to a polyisoprene with a cis-1,4 structure content greater than or equal to 90% and a weight-average molecular weight of 30×10 4 ~400×10 4 , a long-chain branched high-cis polyisoprene with a branching factor of 0.40 to 0.99, and preparing the long-chain branched polyisoprene by reacting a linear high-cis polyisoprene with a difunctional or multifunctional organic compound A method for high cis polyisoprene. Background technique: [0002] Natural rubber is mainly composed of polyisoprene, and the cis content accounts for more than 98%. Natural rubber has good molecular structure regularity, good cold resistance, can crystallize under stretching, and has self-reinforcing effect. Therefore, natural rubber has high strength and is an ideal rubber species in tire tread rubber. With the rapid development of the automobile industry, natura...

AI Technical Summary

Problems solved by technology

Star-branched polyisoprene is prepared by anionic polymerization of isoprene to prepare polyisoprene active chains and then conducts coupling reaction with hyperbranched multifunctional terminators, but the coupling efficiency is lower than 64%. The formula content is even lower than 75%, see Synthetic Rubber Industry.2010,33:183~186

These short-chain branched polyisoprene or star-shaped hyperbranched polyisoprene cannot solve the problems of current high-cis isoprene rubber due to their relatively low cis content, relatively short branched chains, and relatively low molecular weight. For example, the presence of short chain branches may also reduce the strain crystallization properties of macromolecular chains

[0005] US2005 / 0261453A1 and US7319126B2 disclose a method for preparing three-arm or four-arm star-branched high-cis polyisoprene by using rare earth catalyst coordination polymerization and coupling agent termination method, using rare earth metal phosphonate, alkane The catalyst composed of aluminum base or alkylaluminum hydride, alkylaluminum halide and conjugated diene catalyzes the polymerization of isoprene at -55°C to 55°C to obtain a linear polyisoprene chain, and then adds a coupling agent halogenated Metal salts (commonly TiCl 4 , SnCl 4 or PCl 3 ) or halogenated organometallic salts (RnM’X 4-n , R is an aliphatic, alicyclic or aromatic group, M' is a IV or V metal, X is a halogen, n is 1 to 3) react to obtain a star-shaped three-arm or four-arm polyisoprene, wherein The cis-1,4 structure content is greater than 97%, and the weight average molecular weight is 28×10 4 ~148×10 4 , but the coupling efficiency is lower than 60%, the link between the coupling agent residue and the polymer chain is weak, and may be broken during the vulcanization process, see Elastomer, 1997, 7:34~37; 2001, 11:6~8