Block copolymer elastomer catheter balloons
View Patent ↗Balloons for medical devices, particularly balloon angioplasty catheters, are made from particular block copolymer thermoplastic elastomers in which the block copolymer is made up of hard segments of a polyester or polyamide and soft segments of polyether; the polyester hard segments are polyesters of an aromatic dicarboxylic acid and a C 2 -C 4 diol; the polyamide hard segments are polyamides of C 6 or higher carboxylic acids and C 6 or higher organic diamines or of C 6 or higher aliphatic ω-amino-α-acids, and the polyether soft segments are polyethers of C 2 -C 10 , diols; the block copolymer has a low flexural modulus, namely less than 150,000 psi; the block copolymer has a hardness, Shore D scale, of greater than 60; and the percentage by weight of the block polymer attributable to the hard segments is between about 50% and about 95%. The polymers provide high strength, thin wall, compliant and semi-compliant balloons, which leads to a low profile catheter. The low profile catheters have very good initial crossing, good trackability, good recrossing after first inflation.
1. A medical device comprising a balloon, the balloon formed from a block copolymer thermoplastic elastomer polymer, the polymer being characterized by a flexural modulus of 150,000 psi or less and a Shore D hardness of at least 60, the balloon having a single wall thickness of less than 0.001 inches and a wall strength in excess of 15,000 psi.
2. A medical device as in claim 1 wherein the wall strength of the balloon is in excess of 20,000 psi.
3. A medical device as in claim 1 wherein the polymer is further characterized by an ultimate elongation of 300% or higher.
4. A medical device as in claim 1 wherein the balloon has a nominal diameter of 1.5-10 mm.
5. A medical device as in claim 1 further comprising a catheter having a distal end, said balloon being mounted on the catheter near said distal end.
6. A medical device as in claim 1 wherein the block copolymer is further characterized by a ultimate tensile strength of at least 6,000 psi.
7. A medical device as in claim 1 wherein the polymer has a Shore D hardness of at least 63.
8. A medical device as in claim 1 wherein the block copolymer has a Shore D hardness in the range of 65-75 and a flexural modulus in the range of 50,000-120,000 psi.
9. A medical device as in claim 8 wherein the block copolymer is represented by the formula:
in which PA is a polyamide segment of molecular weight in the range of 500-8,000; PE is a polyether segment of molecular weight in the range of 500-2,500 and the repeating number n is between 5 and 10.
10. A medical device as in claim 9 wherein the block copolymer segment, PA, is an aliphatic polyamide of one or more C 10 -C 12 aliphatic acids and one or more C 10 -C 12 aliphatic diamines or of a C 10 -C 12 aliphatic ω-amino-α-acid.
11. A medical device as in claim 9 wherein the polyamide segment, PA, is selected from the group consisting of nylon 12, nylon 11, nylon 9, nylon 6, nylon 6/12, nylon 6/11, nylon 6/9 and nylon 6/6.
12. A medical device as in claim 9 wherein the polyamide segment, PA, is nylon 12 of a molecular weight of 3,000-5,000, and the polyether segment, PE, is poly(tetramethylene ether) of molecular weight between 500 and 1250.
13. A medical device as in claim 9 wherein the polyamide segments, PA, comprise between 80 and 90% by weight of the polyamide/polyether polyester.
14. A medical device as in claim 9 wherein said polyether segment, is selected from the group consisting of poly(tetramethylene ether), poly(pentamethylene ether) and poly(hexamethylene ether).
15. A medical device as in claim 1 wherein the polymer is a polyether-block-amide copolymer comprising at least two polyamide hard segments and at least two polyether soft segments.
16. A medical device as in claim 15 wherein the polyamide hard segments are polyamides of C 6 or higher carboxylic acids and C 6 or higher organic diamines or of C 6 or higher aliphatic ω-amino-α-acids, and the polyether soft segments are polyethers of C 2 -C 10 diols.
17. A medical device as in claim 16 wherein the percentage by weight of the block copolymer attributable to the hard segments is between about 50% and about 95%.
18. A medical device as in claim 1 wherein the polymer is a polyester-block-ether copolymer comprising at least two polyester hard segments and at least two polyether soft segments.
19. A medical device as in claim 18 wherein the polyester hard segments are polyesters of an aromatic dicarboxylic acid and a C 2 -C 4 diol and the polyether soft segments are polyethers of C 2 -C 10 diols.
20. A medical device as in claim 19 wherein the percentage by weight of the block copolymer attributable to the hard segments is between about 50% and about 95%.
21. A medical device as in claim 18 wherein said polyester segments are polyesters of an acid selected from the group consisting of ortho-, meta- or para- phthalic acid, napthalenedicarboxylic acid and meta-terphenyl-4,4′-dicarboxylic acids and a diol selected from the group consisting of ethylene glycol, 1,3-propane diol and 1,4-butane diol.
22. A medical device as in claim 18 wherein the block copolymer is poly(butylene terephthalate-block-poly(tetramethylene oxide).