Medical Catheter Tubes and Process for Production Thereof

Abstract

A medical catheter tube containing a tetrafluoroethylene polymer, which has a wall thickness of 0.1 mm or below and exhibits a tensile strength (S1) at 1.0 mm displacement of 5.0 N/mm or above; and a process for the production of medical catheter tubes, characterized by molding a composition both a tetrafluoroethylene polymer and a lubricant having high affinity for the polymer by paste extrusion. The invention provides thin-wall medical catheter tubes excellent in elongation resistance, kink resistance and internal cavity lubricity.

1 . A medical catheter tube containing a tetrafluoroethylene polymer, characterized by having a wall thickness of 0.1 mm or less and a tensile strength (S1) as determined at a displacement of 1.0 mm of 5.0 N/mm 2  or more. 
   
   
       2 . The medical catheter tube according to  claim 1 , wherein the melting point peak is 320° C. or higher. 
   
   
       3 . A medical catheter tube containing a tetrafluoroethylene polymer, characterized by having a wall thickness of 0.1 mm or less and a birefringence (Δn1) of 2.5×10 −3  or more. 
   
   
       4 . The medical catheter tube according to  claim 3 , wherein the tensile strength (S1), as determined at displacement of 11.0 mm, is 5.0N/mm 2  or more. 
   
   
       5 . The medical catheter tube according to  claim 1 , wherein the tensile strength (S1) as determined at a displacement of 1.0 mm and the birefringence (Δn1) of the medical catheter tube satisfy the following relationship:
     S 1≧1700.0 ×Δn 1+3.0   
   
   
       6 . A medical catheter tube improved in tensile strength, characterized in that the medical catheter tube contains a tetrafluoroethylene polymer; the polymer particles contained in the tetrafluoroethylene polymer are oriented in the axial direction of the catheter tube while the tetrafluoroethylene polymer is paste extrusion molded in the presence of a lubricant higher in compatibility with the tetrafluoroethylene polymer; and the distance among the polymer particles is shortened as the lubricant in the catheter tube is evaporated during drying. 
   
   
       7 . The medical catheter tube according to aims  claim 1 , wherein the tetrafluoroethylene polymer is oriented in the longitudinal direction. 
   
   
       8 . A method of producing the medical catheter tube according to  claim 1 , characterized by molding a composition containing the tetrafluoroethylene polymer and a lubricant higher in compatibility with the polymer by paste extrusion. 
   
   
       9 . The production method according to  claim 8 , wherein the tetrafluoroethylene polymer powder is a tetrafluoroethylene polymer powder prepared by emulsion polymerization method. 
   
   
       10 . The production method according to  claim 8 , wherein the lubricant is a lubricant containing a fluorine-containing chemical. 
   
   
       11 . The production method according to  claim 8 , wherein the boiling point of the lubricant is 100° C. or higher. 
   
   
       12 . The production method according to  claim 8 , wherein the difference (T1−T2) between the interfacial tension (T1) of the tetrafluoroethylene polymer and the interfacial tension (T2) of the lubricant is less than 3.6 dyne/cm. 
   
   
       13 . The production method according to  claim 8 , further including a drying step of heating at a temperature of the lubricant's boiling point or more. 
   
   
       14 . The production method according to  claim 13 , further including a sintering step of heating at a temperature of the tetrafluoroethylene polymer's melting point or more after the drying step. 
   
   
       15 . A method of producing a medical catheter tube containing a tetrafluoroethylene polymer, characterized by including:
 (a) an extrusion molding step of obtaining a molded tube by paste-extrusion molding the tetrafluoroethylene polymer in the presence of a lubricant higher in compatibility with the tetrafluoroethylene polymer for orientation of polymer particles contained in the tetrafluoroethylene polymer in the axial direction of the catheter tube;   (b) a drying step of drying the molded tube at a temperature of the lubricant's boiling point or more, for removal of at least part of the lubricant contained in the molded tube and shortening of the distance among the particles contained in the tetrafluoroethylene polymer; and   (c) a sintering step of sintering the molded tube after the drying step at a temperature of the tetrafluoroethylene polymer's melting point or more for fusion of the particles contained in the tetrafluoroethylene polymer with each other.