| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to form a balloon to a helical shape at the time of balloon dilation and to exactly position and fix the balloon by making the thickness of the balloon after molding nonuniform in a circumferential direction and setting the maximum thickness of the balloon at a specific range of a minimum thickness at the time of molding of a hollow tube by blow molding to the balloon. SOLUTION: Polyurethane is used as the material of the helical balloon and a tube of, for example, 0.23 mm diameter/0.40 mm diameter in an inside diameter/outside diameter is extrusion molded from the material. At this time, the thickness of the balloon after the molding is made nonuniform in the circumferential direction by deliberately offsetting the centering of the die and inner pin of an extruder and the balloon is so formed that 'the maximum value of the thickness'/'the minimum value of the thickness' of the balloon is confined within a range of 1.3 to 8 times. The tube is biaxially stretched by blow molding in such a manner that the outside diameter of the balloon after the molding attains 1.00 mm diameter, by which the balloon is formed. As a result, the shape at the time of the balloon dilation is made helical. The exact positioning and fixing of the balloon are thus made possible. |
