Method of making an improved balloon cuff tracheostomy tube
View Patent ↗There is provided a method of making a balloon having a differential thickness. The method uses a raw tube composed of a thermoplastic polymer which is placed in an asymmetrical mold. The tube is preheated in the mold to a temperature sufficient to soften the material of the tube and inflated with a gas to generally uniformly stretch the material of the tube while allowing the tube to retract lengthwise, thus forming a balloon. The resulting completed balloon has a differential wall thickness wherein the upper region has a thickness of from about 15 to about 30 micrometers and the lower region has a thickness of from about 5 to about 15 micrometers.
1. A method for making a balloon having differential wall thickness comprising the steps of:
placing a raw tube having a lumen in an asymmetrical mold, said mold having an opening on each end through which the tube protrudes;
holding said tube tightly on each end of said mold;
preheating said mold and tube to a temperature between 50 and 120 ° C.;
stretching said tube about 50 to 200 percent over a time period of between 5 and 60 seconds with pressure applied internally with air, nitrogen or another inert gas at about 0.5 bar, while the temperature is maintained;
pressurizing said tube with pressure applied internally with air, nitrogen or another inert gas at a pressure between about 0.5 and 2 bar while allowing said tube to retract lengthwise by 10 to 50 percent over a time period of between 5 and 15 seconds, to form a balloon;
heating the tube while still in the mold with its ends held tightly, to a temperature of 130-165 ° C. for a time of about 30-90 seconds and at a pressure to keep the balloon inflated;
cooling said balloon at about 20-50 ° C.;
collapsing said balloon so that it may be withdrawn without damage;
removing said balloon from said mold;
wherein the completed balloon has differential wall thicknesses, consisting of a continuous upper region having a thickness of from 15 to about 30 micrometers and consisting of a continuous lower region having a thickness of from about 5 to 15 micrometers.
2. The method of claim 1 wherein said raw tube comprises a thermoplastic polymer, said tube having an asymmetric wall thickness.
3. The method of claim 2 wherein said thermoplastic polymer is selected from the group consisting of thermoplastic polyurethane polymers, thermoplastic polyolefin elastomers, thermoplastic polyolefin block copolymers, SBS di-block elastomers, SEBS tri-block elastomers, polyvinyl chloride, low density polyethylene, polyethylene terephthalate and blends and mixtures thereof.