Flexible Medical Tubing Having Kink Resistant Properties And Methods And Apparatus To Produce The Same

Abstract

A flexible, kink-resistant medical tube and a method and apparatus for making the same are provided. The tube includes a body having a first end, a second end, an outer surface and an inner surface. The tube includes a lumen defined by the inner surface of the body and extending between the first end and the second end. The tube also includes a helical structure within in the body.

1 . A method for making a flexible, kink-resistant medical tube having a body and a lumen, the method comprising:
 extruding a the flexible tube by flowing liquid polymer through a the flow channel configured to form a tube; and   inducing a helical rotational flow of the liquid polymer material as the liquid polymer material flows through the flow channel;   wherein the helical flow creates a helical structure within the body of the tube, resisting formation of kinks along the body of the tube.   
     
     
         2 . The method of  claim 1  further comprising:
 providing a first liquid polymer material to the; flow channel; 
 providing a second liquid polymer material to the; flow channel; 
 wherein the first liquid polymer material forms the body of the tube; 
 wherein the helical structure comprises at least one helically oriented segment extending longitudinally along the body of the tube, wherein the at least one helically oriented segment is formed of the second liquid polymer material. 
 
     
     
         3 . The method of  claim 2  wherein said providing a second liquid polymer material comprises supplying the second liquid polymer material to the flow channel from at least three distinct locations and further wherein the helical structure comprises at least three helically oriented segments extending longitudinally along the body of the tube, wherein the helically oriented segments are formed of the second liquid polymer material. 
     
     
         4 . The method of  claim 3  wherein the at least three helically oriented segments are evenly spaced around the circumference of the tube and are embedded in the body of the tube adjacent to the outer surface of the tube, and further wherein the first liquid polymer material is a PVC material having a first hardness and the second liquid polymer material is a PVC material having a second hardness, wherein the second hardness is greater than the first hardness. 
     
     
         5 . The method of  claim 1  wherein the helical flow is induced by a helical groove formed in one of the surfaces that defines the flow channel. 
     
     
         6 . The method of  claim 5  wherein the helical groove is a spiral groove formed in a tapered portion of the an inner surface of the flow channel. 
     
     
         7 . The method of  claim 1  wherein helical flow is induced by rotating at least a portion of an outer surface of the flow channel. 
     
     
         8 . The method of  claim 7  wherein the outer surface of the flow channel is a coextrusion bushing and the rotating portion of the outer surface is a bushing insert rotatably coupled to the bushing, wherein the bushing insert rotates relative to the coextrusion bushing to induce helical flow as the liquid polymer flows through the flow channel. 
     
     
         9 . The method of  claim 8  wherein a helical groove is formed in an inner surface of the flow channel, wherein helical flow is induced by both the rotation of the bushing insert and by the helical groove. 
     
     
         10 . The method of  claim 7  wherein the entire outer surface of the flow channel rotates relative to an inner surface of the flow channel to induce the helical flow. 
     
     
         11 . The method of  claim 1  wherein the helical structure comprises helically aligned polymer chains within the body of the tube. 
     
     
         12 . (canceled) 
     
     
         13 . A flexible, kink-resistant medical tube comprising:
 a polymeric body having a first end, a second end, an outer surface and an inner surface;   a lumen defined by the inner surface of the body and extending between the first end and the second end; and   a polymeric helical structure within the body.   
     
     
         14 . The medical tube of  claim 13  wherein the body is made from a first polymer material and the helical structure is made from a second polymer material, wherein the helical structure comprises at least one helically oriented segment made from the second polymer material embedded in the body. 
     
     
         15 . The medical tube of  claim 14  wherein the helical structure comprises at least three helically oriented segments made from the second material embedded in the body, wherein the first polymer material has a first hardness and the second polymer material has a second hardness, wherein the first hardness is less than the second hardness. 
     
     
         16 . The medical tube of  claim 15  wherein the tube is formed by extrusion, wherein the first polymer material is a first PVC material and the second polymer material is a second PVC material, and further wherein the at least three helically oriented segments are evenly spaced around the circumference of the tube and are embedded in the body of the tube adjacent to the outer surface of the tube. 
     
     
         17 . The medical tube of  claim 16  wherein the first polymer material has a Shore A durometer between 60 and 80 and the second polymer material has a Shore A durometer between 80 and 90. 
     
     
         18 . The medical tube of  claim 13  coupled to a medical device. 
     
     
         19 . An extrusion die system for making a flexible, kink-resistant medical tube comprising:
 an extrusion die body defining an internal cavity having an inlet and an outlet;   an extrusion die pin received within the internal cavity of the die body such that a die flow channel is defined between an outer surface of the die pin and an inner surface of the die body, the die flow channel extending between the inlet and the outlet of the die body, the die pin comprising a helical groove formed on the outer surface of the die pin;   a first inlet structure configured to deliver a first plastic material to the inlet of the die body;   a second inlet structure configured to deliver a second plastic material to the inlet of the die body;   wherein the helical groove induces helical rotation of liquid plastic material as it flows through the die flow channel.   
     
     
         20 . The extrusion die system of  claim 19  wherein the extrusion die pin has a longitudinal axis, wherein the diameter of the extrusion die pin decreases from an inlet side of the extrusion die pin to an outlet side of the extrusion die pin, wherein the dimension of the helical groove parallel to the longitudinal axis decreases as the diameter of the extrusion die pin decreases. 
     
     
         21 . The extrusion die system of  claim 19  further comprising:
 an insert rotatably coupled to the extrusion die body such that the insert surrounds the outlet; 
 a gear coupled to the insert; and 
 an actuator coupled to the gear, wherein the actuator is configured to rotate the gear and the insert; 
 wherein rotation of the insert induces helical rotation of liquid plastic material as it flows through the insert.