Balloon and manufacture thereof

Claim 1

and a radial expansion of less than 10% at 500 psi (3.4 MPa)..]. .[.4. Balloon of claim 3 wherein the polymer is a polyethylene terephthalate homopolyester having an intrinsic viscosity of 0.8 to 1.1..]..[.5. Process for forming a high molecular weight, biaxially oriented, flexible polymeric balloon, the process comprising, at a temperature within the range extending from the second order transition temperature to the first order transition temperature, drawing a polymeric tubing having a finite length (L 1 ) and an internal diameter (ID) which is about one-half the outer diameter (OD) to a length (L 2 ) which is 3 to 6 L 1 , and thereafter expanding the drawn tubing of internal diameter ID 1 and outer diameter OD 1 by expanding means to an internal diameter (ID 2 ) which is 6 to 8 ID and an outer diameter (OD 2 ) which is about 3 to 4 OD, followed by cooling the drawn and expanded tubing to less than its second order transition temperature, said balloon thus formed having a burst pressure of at least 200 psi (1.4 MPa) and a radial expansion beyond nominal inflated diameter of less than 5% at 200 psi (1.4 MPa)..]. .[.6. Process of claim 5 wherein the expanding means is pressurized fluid applied to the inside of the tubing..]. .[.7. Process of claim 6 wherein the pressurized fluid is a pressurized gas..]. .[.8. Process of claim 5 wherein the tubing is formed by extrusion of polyethylene terephthalate homopolyester resin having an intrinsic viscosity of 1.0 to 1.3 and a density of 1.35 to 1.45 and the balloon has a burst pressure of at least 400 psi (2.8 MPa)..]. .[.9. Process of claim 8 wherein the temperature is in the range 84°-99° C..]. .[.10. Process of claim 8 wherein the temperature is in the range 86°-96° C..]. .[.11. Process of claim 8 wherein the tubing drawing temperature is different from the tubing expanding temperature..]. .[.12. Dilatation balloon catheter comprising the balloon of claim 1..].