Thermal treatment of irradiated propylene polymer material
AssigneeHimont Incorporated
InventorAnthony J. DeNicola, Jr.
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Abstract
Disclosed is a method of treating a free-radical-containing, optionally room-temperature-aged, irradiated, normally solid high-molecular-weight, semi-crystalline propylene polymer material at about from 40.degree. C. to 110.degree. C. for at least about 10 minutes before being exposed to the higher temperatures that deactivate the residual free radicals therein. Treatment of the polymer at the intermediate temperature causes recombination, and better utilization, of free radicals with the production of more long-chain branching. A two-stage fluid bed process, with a first stage at the intermediate temperature for radical recombination and a second radical-deactivation stage at a higher temperature, is preferred.
Claims12
In a method of making high-molecular-weight, long-chain branched propylene polymer material from linear semi-crystalline normally solid propylene polymer material in an environment in which an active-oxygen concentration of less than about 15% by volume is maintained, which method includes the steps of irradiating said linear polymer material with high-energy ionizing radiation and thermally deactivating residual free radicals in the irradiated polymer material, the improvement comprising heating the irradiated polymer material at a temperature in the range of about from 40.degree. C. to 110.degree. C. for at least about 10 minutes prior to deactivating residual free radicals.
A method of treating irradiated propylene polymer material comprising, in an environment in which an active-oxygen concentration of less than about 15% by volume is maintained, heating a free-radical-containing irradiated semi-crystalline propylene polymer material in a first stage at a temperature T.sub.1 in the range of about from 40.degree. C. to 110.degree. C. for at least about 10 minutes, and in a second stage at a temperature T.sub.2 of at least about 120.degree. C. for a time sufficient to allow deactivation of substantially all residual free radicals.
Dependencies are inferred from the claim text.