Patent ID: 7056971

Claim:
A plasticized sealant against diffusion of oxygen, the sealant consisting essentially of a thermoplastic elastomer free of tackiness selected from the group consisting of (a) an at least partially hydrogenated polyblock copolymer of a vinylaromatic compound and a conjugated diene, so as to include a block of a mono(lower)olefin, the olefin having from 2 to 4 carbon atoms, and, (b) a thermoplastic vulcanizate, wherein (a) is block copolymer having vinylaromatic end-blocks and a mid-block selected from the group consisting of polyisoprene, polybutadiene, and hydrogenated copolymers thereof, (a) having uniformly distributed therewithin, from 5 to 150 phr, based on 100 parts by weight of (a), of a polymer of an olefin having from 2 to 4 carbon atoms, the polymer having a melt index in the range from 0.2 to 200 gm/10 min at 230° C. and 2.16 Kg load, combined with from zero to an equivalent amount by weight of a mono(lower)olefinic rubber having Mn greater than 200,000, and (a) and (b) having blended therein from 20 to 180 phr of a liquid polyisobutene oil plasticizer, based on 100 parts by weight of (a) and (b), having a number average molecular weight (“Mn”) in the range from 200 to 6000, fluidizable under melt-blending conditions of (a) and (b), the polyisobutene selected from the group consisting of (i) a homopolymer of polvisobutylene and (ii) a copolymer of isobutene and butene, butene repeating units being present in a minor molar proportion, the amount of polyisobutene oil to provide the plasticized sealant with a hardness in the range from Shore A 40 to 80 and an oxygen-permeability less than 20,000 cc. (2.54 μm)/m 2 .day.atm at 23° C. and, a compatible amount, from 1 to about 20 phr of a detackifier per 100 parts by weight of (a), (a) having Mn in the range from about 40,000 to 1,100,000 and (b) having a Shore A hardness in the range from 30 to 100, tensile strength at 100% elongation in the range from about 0.5 to 10 MPa and specific gravity in the range from 0.9 to 0.99.