Patent ID: 7128862

Claim:
A method of forming a biaxially oriented multi-layer tube of a medical device, comprising steps of: providing a first polymer and a second polymer to an extruder, co-extruding an inner layer comprising the first polymer and an outer layer comprising the second polymer through a counter-rotating die comprising an inner die rotating in a first direction and an outer die rotating in a second direction opposite that of the first direction, thereby forming a multi-layer tube; rotating the multi-layer tube in a direction equal to the first direction while the multi-layer tube is in a semi-molten state; and cooling the semi-molten multi-layer tube to form a biaxially oriented multi-layer tube; wherein the inner layer of the resulting biaxially oriented multi-layer tube has a biaxial helical orientation on a molecular scale and the outer layer of the resulting biaxially oriented multi-layer tube has an opposing biaxial helical orientation on a molecular scale.