Process for manufacturing polybutylene terephthalate (PBT) catheter balloons
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.
C A A A Y C Y
C08K A61L A61M A61M Y10T C08L Y10T
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Jianhua Lixiao
Chen Wang