Gasket composition for crown caps
AssigneeW.R. Grace & Co.-Conn.
InventorSteven Andrew Carl White
Life of this patent
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Abstract
A gasket for a crown cap to be used on a carbonated beverage, especially a twist-off crown or for a bottle which is to be pasteurized, is formed of a thermoplastic material, which is preferably free of polyvinyl chloride, and which contains a hydrogenated copolymer of styrene and a conjugated diene, or a functionalized derivative thereof. The material is resistant to heat, and provides a gasket with advantageous sealing properties.
Claims13
A container of a carbonated beverage closed with a crown cap having a gasket formed of a thermoplastic material characterised in that the thermoplastic material consists essentially of from 1 to 50% by weight of a hydrogenated copolymer of styrene and a conjugated diene or a functionalised derivative selected from the group consisting of styrene-ethylene-butylene-styrene copolymers and styrene-ethylene-propylene-styrene copolymers, said copolymers being operative for incorporating and retaining oil in said gasket thermoplastic material;
- an oil in an amount such that the ratio of said hydrogenated copolymer to oil is 1:
- to at least 0.5;
- and from 85 to 10% of a rubbery polymer selected from the group consisted of hydrogenated copolymers, polystyrenes, ethylene copolymers with vinylacetate or acrylates, butyl rubber, polybutadiene, styrene butadiene rubber, carboxylated styrene butadiene rubber, polyisoprene, styrene-isoprene-styrene copolymer, ethylene/propylene rubber and styrene butadiene styrene block copolymers;
- whereby the presence of said styrene-ethylene-butylene-styrene copolymers or said styrene-ethylene-propylene-styrene copolymers improves the venting pressure of said container closed with said crown cap and gasket when compared to a gasket comprising said rubbery polymer alone without said styrene-ethylene-butylene-styrene copolymers or said styrene-ethylene-propylene-styrene copolymers.
A carbonated beverage container closed with a crown cap having a gasket comprising:
- a metal crown cap closed on a container containing a carbonated beverage, said crown cap having a gasket comprising a thermoplastic material substantially free of chlorinated olefin-based polymer, said gasket being operative to resist leakage of gas even when subjected to internal pressures within said closed container of at least 5 bar;
- said thermoplastic material comprising an olefin polymer in an amount of 15 to 90% by weight of polymer in the gasket and selected from the group consisting of a polyethylene, polypropylene, an ethylene propylene copolymer, and an ethylene vinyl acetate copolymer;
- said thermoplastic material further comprising a rubbery polymer in the amount of 85-15% by weight of polymer in the gasket, said rubbery polymer being selected from the group consisting of an ethylene propylene rubber, a styrene-isoprene-styrene copolymer, a styrene-butadiene-styrene copolymer, and a butyl rubber;
- and
- said gasket further comprising a hydrogenated styrene-diene copolymer, in an amount of 1-50% by weight of polymer in said gasket, said hydrogenated copolymer being selected from the group consisting of a styrene-ethylene-butylene-styrene copolymer and a styrene-ethylene-propylene-styrene copolymer;
- said hydrogenated styrene-diene copolymer being operative in combination with said thermoplastic material, to increase the average leakage pressure and the minimum leakage pressure exhibited by the gasket, in comparison to a gasket containing said thermoplastic material but without said hydrogenated styrene-diene copolymer.
A carbonated beverage container closed with a lid or cap having a sealant composition comprising:
- a thermoplastic material comprising at least one of (1) an olefin material selected from the group consisting of a polyethylene, a propylene, an ethylene propylene copolymer, and an ethylene vinyl acetate copolymer;
- or (2) a rubbery polymer selected from the group consisting of ethylene propylene rubber, a styrene-isoprene-styrene copolymer, a styrene-butadiene-styrene copolymer, and a butyl rubber;
- and
- a hydrogenated styrene-diene copolymer selected from the group consisting of a styrene-ethylene-butylene-styrene copolymer and a styrene-ethylene-propylene-styrene copolymer, said hydrogenated styrene-diene copolymer being operative in combination with said thermoplastic material to increase the average leakage pressure and the minimum leakage pressure exhibited by the gasket in comparison to a gasket containing said thermoplastic material but without said hydrogenated styrene-diene copolymer.
Dependencies are inferred from the claim text.