Composition and process for manufacturing PBT catheter balloons
First Claim
1. A method of forming a balloon for a medical device, comprising:
- a) providing a length of tubing comprising at least one layer of PBT or PBT block copolymer;
b) after step a), longitudinally stressing the length of tubing at a temperature where necking occurs so as to neck down at least a portion of the tubing length, while subjecting the tubing to a first internal pressure above ambient pressure; and
c) after step b), radially expanding a necked down portion of the tubing at a temperature between 85°
C. and 200°
under a second internal pressure.
1 Assignment
0 Petitions
Accused Products
Abstract
A processing technique and a composition which allow compositions of PBT polymers or copolymers to be formed into blow molded articles, especially medical balloons such as dilatation or stent placement balloons, from extruded tubular parisons. The process includes a longitudinal stretch step run at a temperature below the Tg of the polymeric material and a radial expansion step run at a temperature above the Tg of the polymeric material. During the longitudinal stretch step, the tubing is subjected to high internal pressure. In the composition a small amount of boric acid is added to the polybutylene terephthalate in a melt blend to give a formulation which has reduced crystallinity after extrusion and which can more readily fashioned into high strength blow molded articles than PBT by itself. Articles, which may be formed using the invention include medical device balloon articles in which the polymer consists essentially of PBT optionally blended with boric acid.
8 Citations
29 Claims
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1. A method of forming a balloon for a medical device, comprising:
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a) providing a length of tubing comprising at least one layer of PBT or PBT block copolymer;
b) after step a), longitudinally stressing the length of tubing at a temperature where necking occurs so as to neck down at least a portion of the tubing length, while subjecting the tubing to a first internal pressure above ambient pressure; and
c) after step b), radially expanding a necked down portion of the tubing at a temperature between 85°
C. and 200°
under a second internal pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A process for forming an article from a composition consisting essentially of a polymer material having a high content of butylene terephthalate, the process comprising:
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extruding a hollow parison of the composition;
stressing the extruded hollow parison at a temperature at or below the Tg of the polymer while subjecting the parison to internal pressure under conditions which produce a propagating necking of at least a portion of the extruded parison; and
then radially expanding the necked portion of the parison under pressure at a temperature above the Tg of the polymer material to form the article. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A process for forming an article from poly(butylene terephthalate) optionally mixed with up to 5% by weight of boric acid, the process comprising:
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extruding a hollow parison of the composition; and
without axially stretching the extruded parison,radially expanding the extruded parison under pressure at a temperature above the Tg of the polymer material to form the article.
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20. A process for forming an article from a composition consisting essentially of a polymer material having a high crystallization rate, the process comprising:
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extruding a hollow parison of the composition;
stressing the extruded hollow parison at a temperature at or below the Tg of the polymer while subjecting the parison to internal pressure under conditions which produce a propagating necking of at least a portion of the extruded parison; and
thenradially expanding the necked portion of the parison under pressure at a temperature above the Tg of the polymer material to form the article. - View Dependent Claims (21, 22)
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- 23. A composition prepared by melt mixing a high butylene terephthalate content polymer material with 0.01-5.0% by weight of said composition boric acid.
Specification