Thermoplastic vulcanizates and sealing devices made therewith
An article for sealing the contents of a container, the article comprising a member adapted for sealing the container, where the member includes a thermoplastic vulcanizate including a dynamically cured butyl rubber, a thermoplastic polyurethane having a glass transition temperature of less than about 60° C., and a synthetic oil.
1. An article for sealing the contents of a container, the article comprising:
a member adapted for sealing the container, where the member comprises:
a thermoplastic vulcanizate comprising:
(i) a dynamically cured brominated butyl rubber dispersed within a continuous phase consisting essentially of a polyester-based or polyether-based thermoplastic polyurethane having a glass transition temperature of less than 60° C.,
(ii) from about 30 to about 40 parts by weight, per 100 parts by weight butyl rubber, of a synthetic oil selected from the group consisting of polyisobutylene, poly(isobutylene-co-butene), polybutadiene, and poly(butadiene-co-butene), and
(iii) from about 5 to about 30 parts by weight, per 100 parts by weight of rubber, of carbon black, clay, or combination thereof, wherein: the thermoplastic vulcanizate includes:
from about 20 to about 50 percent by weight thermoplastic polyurethane resin based on the weight of the butyl rubber component and thermoplastic polyurethane component combined, and
wherein:
the dynamically vulcanized butyl rubber is cured to an extent that not more than 5 weight percent of the rubber is extractable by cyclohexane at 23° C.,
the thermoplastic vulcanizate is characterized by:
an LCR viscosity of less than 150 Pa@1,200 s −1 ,
an ACR viscosity of less than 4000 poise,
an oxygen permeability of less than 500 cc/m·m·day,
a compression set of less than 30%, and
a coreability characterized by less than 5 cores per 100 punctures, and the thermoplastic vulcanizate includes less than 1% by weight mineral oils, and the thermoplastic vulcanizate is substantially devoid of a compatibilizer.
2. The article of claim 1 , where the member includes a generally cylindrical body.
3. The article of claim 1 , where the member includes at least two distinct layers, where at least one layer includes the thermoplastic vulcanizate.
4. The article of claim 1 , where the member includes a planar sheet.
5. The article of claim 1 , where the thermoplastic vulcanizate includes from about 25 to about 90% by weight butyl rubber based upon the total weight of the butyl rubber and thermoplastic polyurethane combined.
6. The article of claim 5 , where the thermoplastic vulcanizate further comprises from about 10 to about 15 parts by weight functionalized polyolefin per 100 parts by weight butyl rubber.
7. The article of claim 1 , where the thermoplastic vulcanizate is devoid of mineral oils.
8. The article of claim 1 , where the synthetic oil is an oligomer of one or more butene monomers.
9. The article of claim 1 , where the synthetic oil is characterized by a viscosity in excess of about 20 cp as measured by a Brookfield viscometer according to ASTM D-4402 at 38° C.
10. The article of claim 1 , where the butyl rubber includes one or more parabromomethylstyrenyl mer units.
11. The article of claim 1 , where the dynamically cured butyl rubber is dispersed as fine particles within the thermoplastic polyurethane continuous phase.
12. A container in combination with the article of claim 1 , where the article seals the container.