Thermoplastic elastomers exhibiting superior barrier properties
View Patent ↗A blend of styrene-isobutylene-styrene based thermoplastic elastomer and organoclay-filled polyamide is disclosed which has good processability and more effective barrier properties for oxygen than the blend using amorphous or crystalline polyamide without organoclay.
1. A thermoplastic elastomer compound comprising:
(a) from about 70 to about 85 weight percent of styrene-isobutylene-styrene thermoplastic elastomer; and
(b) from about 15 to about 30 weight percent of polyamide including organoclay dispersed in the polyamide;
wherein the compound has flexibility and oxygen barrier properties such that:
(A) when the compound comprises about 85 weight percent of styrene-isobutylene-styrene thermoplastic elastomer and about 15 weight percent of polyamide including organoclay dispersed in the polyamide, the compound has:
(i) Shore A hardness (ASTM D2240, 10 seconds delay) of 68;
(ii) Percent Elongation (ASTM D412, Die C) of 292; and
(iii) Oxygen Transmission Rate (ASTM D3985 cc·mil/m 2 ·day) of 570; and
(B) when the compound comprises about 70 weight percent of styrene-isobutylene-styrene thermoplastic elastomer and about 30 weight percent of polyamide including organoclay dispersed in the polyamide, the compound has:
(i) Shore A hardness (ASTM D2240, 10 seconds delay) of 89;
(ii) Percent Elongation (ASTM D412, Die C) of 83; and
(iii) Oxygen Transmission Rate (ASTM D3985 cc·mil/m 2 ·day) of 55.
2. The compound of claim 1 further comprising plasticizer oil.
3. The compound of claim 1 further comprising filler.
4. The compound of claim 1 further comprising at least one additive selected from the group consisting of adhesion promoters; biocides; anti-fogging agents; anti-static agents; bonding agents; blowing agents; foaming agents; dispersants; fillers; extenders; fire retardants; flame retardants; smoke suppressants; impact modifiers; initiators; lubricants; micas; pigments; colorants; dyes; oils; plasticizers; processing aids; release agents; silanes; titanates; zirconates; slip agents; anti-blocking agents; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.
5. The compound of claim 1 , wherein the organoclay is exfoliated within the polyamide, and wherein the polyamide comprises from about 1 to about 8 weight percent of the organoclay.
6. A method of using the compound of claim 1 , the method comprising the step of molding the compound into an article that has more than about 280% improvement in reduced oxygen transmission relative to a compound which has the same styrene-isobutylene-styrene thermoplastic elastomer and polyamide but no organoclay.
7. The method of claim 6 , wherein the article is in a form of a seal or a closure.
8. The method of claim 6 , wherein the article is in a form selected from the group consisting of a food or drink container seal, a printer cartridge seal, and a medical container seal.
9. A molded article formed from a thermoplastic elastomer compound comprising:
(a) from about 70 to about 85 weight percent of styrene-isobutylene-styrene thermoplastic elastomer; and
(b) from about 15 to about 30 weight percent of polyamide including organoclay dispersed in the polyamide;
wherein the molded article has flexibility and oxygen barrier properties such that:
(A) when the compound comprises about 85 weight percent of styrene-isobutylene-styrene thermoplastic elastomer and about 15 weight percent of polyamide including organoclay dispersed in the polyamide, the molded article has:
(i) Shore A hardness (ASTM D2240, 10 seconds delay) of 68;
(ii) Percent Elongation (ASTM D412, Die C) of 292; and
(iii) Oxygen Transmission Rate (ASTM D3985 cc·mil/m 2 ·day) of 570; and
(B) when the compound comprises about 70 weight percent of styrene-isobutylene-styrene thermoplastic elastomer and about 30 weight percent of polyamide including organoclay dispersed in the polyamide, the molded article has:
(i) Shore A hardness (ASTM D2240, 10 seconds delay) of 89;
(ii) Percent Elongation (ASTM D412, Die C) of 83; and
(iii) Oxygen Transmission Rate (ASTM D3985 cc·mil/m 2 ·day) of 55.
10. The molded article of claim 9 , wherein the compound further comprises plasticizer oil.
11. The molded article of claim 9 , wherein the compound further comprises filler.
12. The molded article of claim 9 , wherein the compound further comprises at least one additive selected from the group consisting of adhesion promoters; biocides; anti-fogging agents; anti-static agents; bonding agents; blowing agents; foaming agents; dispersants; fillers; extenders; fire retardants; flame retardants; smoke suppressants; impact modifiers; initiators; lubricants; micas; pigments; colorants; dyes; oils; plasticizers; processing aids; release agents; silanes; titanates; zirconates; slip agents; anti-blocking agents; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.
13. The molded article of claim 9 , wherein the organoclay is exfoliated within the polyamide, and wherein the polyamide comprises from about 1 to about 8 weight percent of the organoclay.
14. The molded article of claim 9 , wherein the molded article is in a form of a seal or a closure.
15. The molded article of claim 9 , wherein the molded article is in a form selected from the group consisting of a food or drink container seal, a printer cartridge seal, and a medical container seal.