This technology is available from Temarex Corporation.
Title:PROCESS TO IMPROVE CHEMICAL AND OXIDATIVE STABILITY OF HYDROGENATED POLYMERS
Inventor(s):H.J. Harwood, S. Jolly
Disclosure 227 U.S. Patent 5,597,875
This invention provides a method to obtain thermoplastic elastomers (e.g. Kraton G, a registered trademark of Shell) with increased softening points, good chemical resistance, and improved thermal and chemical stability.
The presence of residual unsaturation in the center blocks is undesirable, because the unsaturation causes the polymers to have limited thermal stability and poor resistance to atmospheric oxygen and ozone.In addition, the polymers are susceptible to halogens and strongly acidic materials.Polymers containing unsaturated monomer units are often hydrogenated to obtain materials that have improved thermal and chemical stability.
Current hydrogenation of unsaturated units in polymers leaves as much as one (1) percent residual unsaturation, as the reaction cannot be conducted completely.This presence of such residual unsaturation adversely affects properties and creates difficulties when attempts are made to modify TPE by nitration or arylsulfonylation.
This invention uses a post-hydrogenation process to remove or significantly lower the amount of residual unsaturation in hydrogenated polymers and copolymers and thereby enhance the chemical resistance of the polymers.
This invention is applicable to hydrogenated polymers derived from butadiene, chloroprene, cyclic polyolefins, hydrogenated products formed by acyclic diene metathesis (ADMET) polymerization, hydrogenated copolymers and terpolymers of vinyl monomers, including acrylates and methacrylates.Additionally, copolymers which contain at least one hydrogenated diene would also be applicable to this invention, e.g., hydrogenated diene-nitrile copolymers such as for example, hydrogenated butadiene-acrylonitrile copolymers.
This invention is also applicable to copolymers which may have statistical, alternating, block, graft, star, or radial block architectures.
This technology is ideally suitable for sterilizable medical plastic devices, seals, gaskets, shoe soles, adhesives, wire coatings, etc. where improved chemical and oxidative stability are required.