Method for making splittable catheter

DETAILED DESCRIPTION OF THE DRAWINGS In FIG.
1, a cross sectional view has been taken as would be seen from the plane normal to axis AA of FIG.
3.
More specifically, the catheter 10 includes a body portion 11 and a stripe material portion 12 each of which combine to form the uniform circular thickness in the cross sectional view.
The body portion is made by co-extrusion with the stripe material portion 12 in a combining extrusion die block.
The body portion 11 is in the preferred embodiment Vialon.
RTM.
polyurethane, a product of Deseret Medical, Inc.
, Sandy, Utah, but other polyurethanes and polymers normally used for catheters will work.
The stripe material portion 12 may be any olefinic material such as and only by way of example, the polyethylene made by El Paso Chemical.
These materials are co-extruded through a specially-designed die which lays the two together and forms a surface therebetween, i.
e.
surface 11a and the body portion 11 and surface 12a on the stripe material portion 12.
The process conditions for the co-extrusion including melting polyurethane polymer of the body in the temperature range of 190.
degree.
to 210.
degree.
C.
and the olefinic polyethylene polymer of the stripe portion 12 at a temperature of about 180.
degree.
to 200.
degree.
C.
and then co-extruding the two together to form simultaneously a catheter body wall thickness of approximately 0.
007 to 0.
011 inches for a 13 to 14 gauge catheter tube with a residual thinned portion B extending from the inside wall of 11b of the catheter 11 in FIGS.
1 and 2 of approximately 0.
003 to 0.
006 inches.
It has been found that the residual thinned portion B is easily split and permits convenient removal of the placement catheter 10 from any guidewire or long-line catheter placed therethrough, notwithstanding the tear strength of Vialon.
RTM.
polyurethane.
The specific Vialon.
RTM.
polyurethane polymer for the preferred embodiment has the following physical characteristics: tensile strength of 6000 psi, 25% modulus 2,000.
+-.
200 psi, Shore D hardness 65