Process for dynamically crosslinked thermoplastic elastomer containing a metal halide antibloom agent
AssigneeMontell North America Inc.
InventorEmmanuel A. Awojulu
Life of this patent
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Abstract
A dynamically crosslinked thermoplastic elastomer composition contains (1) a thermoplastic olefin, (2) an elastomeric copolymer of ethylene and a 3-8 C alpha-olefin, optionally containing a diene, (3) a halide of tin, zinc, or calcium, and (4) an organic peroxide curing agent selected from (a) an aromatic peroxide and (b) a combination of an aromatic and an aliphatic peroxide. Injection molded and extruded articles made from the composition do not exhibit blooming.
Claims5
A process for preventing blooming in molded or extruded articles made from a dynamically crosslinkable thermoplastic elastomer composition containing an aromatic organic peroxide crosslinking agent, the process comprising mixing a dynamically crosslinkable thermoplastic elastomer composition consisting essentially of:
- (1) about 30 parts to about 60 parts by weight of a thermoplastic olefin prepared by sequential polymerization in two or more stages comprising:
- (a) about 20% to about 70% by wt. of a propylene homopolymer having an isotactic index, defined as the xylene insoluble portion, greater than 90, or a crystalline propylene copolymer with ethylene and/or a 4-8 C alpha-olefin having a propylene content greater than 85% by wt. and an isotactic index, defined as the xylene insoluble portion, greater than 85;
- (b) about 30% to about 75% by wt. of an amorphous ethylene-propylene or ethylene-butene-1 polymer, optionally containing about 1% to about 10% by wt. of a diene, which polymer is xylene soluble at room temperature and contains about 30% to about 70% by wt. ethylene, and
- (c) about 3% to about 30% by wt. of a semi-crystalline ethylene-propylene or ethylene-butene-1 copolymer that is xylene insoluble at room temperature and contains greater than 90% by wt. ethylene;
- (2) about 40parts to about 70parts by weight of an elastomeric polymer of ethylene and a 3-8 C alpha-olefin, optionally containing about 1% to about 10% by wt. of a diene, and having an ethylene content of about 30% to about 70% by wt., wherein (1)+(2)=100 parts by weight;
- and
- (3) an organic peroxide crosslinking agent selected from the group consisting of (a) about 0.5 parts to about 4.0 parts per hundred parts of (1)+(2) of an aromatic peroxide, and (b) a combination of about 0.3 parts to about 2.0 parts of an aromatic peroxide and about 0.2 parts to about 1.5 parts of an aliphatic peroxide, per hundred parts of (1)+(2),
- with about 0.4 parts to about 6.0 parts per hundred parts of (1)+(2) of a metal halide antiblooming agent selected from the group consisting of the halides of tin, zinc, and calcium,
- wherein the weight ratio of the metal halide to the aromatic peroxide is at least 0.6.
Dependencies are inferred from the claim text.