Method of increasing the tensile strength of a dilatation balloon

A method of making a thin wall dilatation balloon having a high percentage of the maximum tensile strength of the balloon material, the method comprising the steps of:

• heating a thin wall, tubular parison of a biaxially orientable semi-crystalline polymer to achieve a radially decreasing temperature gradient across the sidewall of the parison going from the inner to the outer surfaces of the parison, the outer surface being heated to a temperature no less than the orientation temperature of the polymer, and the parison having a wall thickness of no greater than about 25 mils;
• axially drawing and circumferentially expanding the parison while subject to said temperature gradient, said circumferential expansion being achieved by sealing one end of the parison and injecting a heated fluid to expand the parison;
• and
• wherein the temperature gradient is selected to compensate for differing degrees of stretch across the sidewall and produce the thin wall dilatation balloon having a substantially uniform and relatively high degree of orientation across the sidewall and thus a high average tensile strength.

A method of making a thin wall dilatation balloon from a tubular parison, wherein although the parison is expanded at substantially different inner and outer diameter stretch ratios, the resulting expanded article has a high percentage of the maximum tensile strength of the parison material, the method comprising the steps of:

• heating a thin wall, tubular parison of a biaxially orientable polymer by flowing a heated fluid through the interior of the parison to achieve a radially decreasing temperature gradient across the sidewall of the parison going from the inner to the outer surfaces of the parison, the outer surface being heated to a temperature no less than the orientation temperature of the polymer and the parison having a wall thickness of no greater than about 25 mils;
• axially drawing and circumferentially expanding the parison while subject to said temperature gradient, said circumferential expansion being achieved by sealing one end of the parison and injecting a heated fluid to expand the parison, and wherein the inner and outer diameter stretch ratios differ by at least about 25%;
• and
• wherein the temperature gradient across the sidewall is selected to compensate for the differing degrees of stretch across the sidewall and produce the thin wall dilation balloon having a substantially uniform and relatively high degree of orientation across the sidewall and thus a high average tensile strength.

A method of making a thin wall dilatation balloon having a high percentage of the maximum tensile strength of the balloon material, the method comprising the steps of:

• heating a thin wall, tubular parison of a biaxially orientable, semi-crystalline polymer to achieve a radially decreasing temperature gradient across the sidewall of the parison going from the inner to the outer surfaces of the parison, the outer surface being heated to a temperature no less than the orientation temperature of the polymer and the parison having a wall thickness of no greater than about 25 mils;
• axially drawing and circumferentially expanding the parison while subject to said temperature gradient, said circumferential expansion being achieved by sealing one end of the parison and injecting a heated fluid to expand the parison, and
• wherein the temperature gradient is selected to compensate for differing degrees of stretch across the sidewall to produce the thin wall dilatation balloon having a substantially unmiform and relatively high degree of orientation across the sidewall and thus a high average tensile strength, and
• heat setting the drawn and circumferentially expanded parison by elevating the temperature of the formed balloon and maintaining the temperature for a period of time sufficient for heat setting the balloon and ensuring the dimensional stability of the balloon.