Styrene-Butadiene Block Copolymers For Tubing Applications

摘要

Conjugated diene monovinylarene block copolymers having superior kink resistance properties are disclosed. These copolymers can be used to produce tubing and other end-use articles, and can be a replacement for flexible PVC.

主权项

1. A process to produce a kink-resistant conjugated diene monovinylarene block copolymer comprising from about 35 phm to about 70 phm monovinylarene monomer, the process comprising sequentially contacting under polymerization conditions:
(i) a first initiator charge and a first charge of the monovinylarene monomer; (ii) a second initiator charge and a second charge of the monovinylarene monomer; (iii) a first dual charge of the monovinylarene monomer and the conjugated diene monomer, wherein the monovinylarene monomer content of the first dual charge is from about 30 wt. % to about 80 wt. %; (iv) optionally, a second dual charge of the monovinylarene monomer and the conjugated diene monomer, wherein the monovinylarene monomer content of the second dual charge is from about 30 wt. % to about 80 wt. %; (v) a final charge of the monovinylarene monomer and the conjugated diene monomer or the conjugated diene monomer, wherein the conjugated diene monomer content of the final charge is at least about 70 wt. %; and (vi) a coupling agent; wherein the first charge and the second charge comprise a total of from about 10 phm to about 45 phm of the monovinylarene monomer; and wherein a kink resistance of tubing produced from the copolymer and tested in accordance with DIN EN 13868 is less than or equal to about 32 mm.