THERMOOXIDATIVE STABILIZATION OF POLYOLEFINS WITH AN OXO-PIPERAZINYL-TRIAZINE AND A PHOSPHOROUS ACID ESTER

摘要

Only two symmetrical stabilizers in a polyolefin or copolymer thereof, provide thermooxidative ("TO") or antioxidative ("AO") stability. One is an arylphosphite or arylfluorophosphite; the other is a monomolecular tri-substituted triazine in which each of three chlorine atoms on a trihalo-s-triazine is substituted with a piperazinone in which the N atom in the 4-position is alkylated. Only a trace amount of phosphite, at least 0.01 phr but less than 0.1 phr, is used so that the ratio of the piperazinone-substituted stabilizer to ester is greater than 1; additional phosphite has no noticeable effect. The trace amount of phosphite has a surprising booster effect, giving the stabilized composition excellent TO stability. Articles thermoformed from the stabilized polyolefin or copolymer thereof may be used under the hood or the dash of a vehicle, and, in containers for packaging goods, all of which articles are subject to TO degradation even if they are not subject to ultraviolet light degradation.