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US 7,935,740 B2Granted
Process for producing high melt strength polypropylene
AssigneeBasell Poliolefine Italia S.r.l.
InventorsVu A. Dang, Dinshong Dong, Theodore Dziemianowicz
Life of this patent
Estimating the term…
Abstract
The present subject matter relates to processes for irradiating visbroken propylene polymer compositions or extrudates of propylene polymer compositions containing a propylene polymer having a low polydispersity index and a non-phenolic stabilizer.
Claims17
A process comprising:
- irradiating an extrudate comprising a propylene polymer composition with about 1 to about 20 Megarad of radiation to form an irradiated extrudate;
- the propylene polymer composition being irradiated in a reduced oxygen environment, wherein active oxygen is in an established and maintained concentration of less than about 15% by volume, with respect to a total volume of the reduced oxygen environment;
- maintaining the irradiated extrudate in the reduced oxygen environment for a period of time sufficient for a significant amount of long chain branches to form within the irradiated extrudate;
- and
- treating the irradiated extrudate while the irradiated extrudate is in the reduced oxygen environment to substantially deactivate free radicals present in the irradiated extrudate,
- wherein the propylene polymer composition comprises:
- (A) a propylene polymer having a polydispersity index between 2.1 and 3.4;
- and
- (B) 0.001 to 1 pph of a non-phenolic stabilizer selected from hindered amines, hydroxylamines, nitrones, amine oxides, benzofuranones, organic phosphites, phosphonites or mixtures thereof, based on the weight of the propylene polymer.
6 more elements
A process comprising:
- treating a propylene polymer composition with an organic peroxide to form a visbroken product having a polydispersity index between 2.1 and 3.4, the propylene polymer composition comprising:
- (A) a propylene polymer;
- and optionally
- (B) 0.001 to 1 pph of a non-phenolic stabilizer selected from hindered amines, hydroxylamines, nitrones, amine oxides, benzofuranones, organic phosphites, phosphonites or mixtures thereof, based on the weight of the propylene polymer;
- irradiating the visbroken product with about 1 to about 20 Megarad of radiation to form an irradiated, visbroken product;
- the visbroken product being irradiated in a reduced oxygen environment, wherein active oxygen is in an established and maintained concentration of less than about 15% by volume, with respect to a total volume of the reduced oxygen environment;
- maintaining the irradiated, visbroken product in the reduced oxygen environment for a period of time sufficient for a significant amount of long chain branches to form within the irradiated, visbroken product;
- and
- treating the irradiated, visbroken product while the irradiated, visbroken product is in the reduced oxygen environment to substantially deactivate free radicals present in the irradiated, visbroken product.
6 more elements
Dependencies are inferred from the claim text.