Photo-curing of thermoplastic coatings

Abstract

The present invention relates to a method for the preparation of a medical device element by means of extrusion or injection moulding and to medical devices comprising such extruded or injection moulded medical device elements. The medical device elements (e.g. tubes, wires, lines, stents, catheters, guides, endodontic instruments, needles, trocars for e.g. laparoscopic surgery, laparoscopic accessories, surgical instruments, guide wires) are characterized by a prefabricated shaped article or a thermoplastic substrate polymer having thereon a layer of a covalently cross-linked coating composition of a thermoplastic matrix polymer and a hydrophilic polymer. The method involves a coating composition comprising a thermoplastic matrix polymer, a hydrophilic polymer, and one or more photo-initiator(s), e.g. covalently linked to molecules of the thermoplastic matrix polymer and/or to molecules of the hydrophilic polymer. The coating composition is irradiated with UV or visible light so as to covalently cross-link said coating composition.

What is claimed: 
     
         1 . A method for the preparation of a medical device element, the method comprising the steps of:
 (i) providing a prefabricated shaped article or a thermoplastic substrate polymer;   (ii) providing a coating composition comprising a thermoplastic matrix polymer, a hydrophilic polymer, optionally a third polymer, and one or more photo-initiator(s) covalently bound to one or more of the thermoplastic matrix polymer, the hydrophilic polymer, or the optional third polymer;   (iii) extruding, injection molding or powder coating the coating composition onto a surface of the prefabricated shaped article or the substrate polymer, to provide a surface treated prefabricated shaped article or a surface treated thermoplastic substrate polymer; and   (iv) irradiating the surface treated prefabricated shaped article or surface treated thermoplastic substrate polymer with UV or visible light, wherein covalent crosslinks are formed among the polymers of the coating composition.   
     
     
         2 . The method according to  claim 1 , wherein the one or more photo-initiator(s) is at least two different photo-initiators. 
     
     
         3 . The method according to  claim 1 , wherein said one or more photo-initiators are covalently linked to molecules of the thermoplastic matrix polymer and/or to molecules of the hydrophilic polymer. 
     
     
         4 . The method according to  claim 1 , wherein the one or more photo-initiator moieties are covalently linked to a polymer selected from the group consisting of polyurethanes, polyethylene glycols, poly(lactic acid)s, collagen, nylons, vinyl polymers, and polysaccharides. 
     
     
         5 . The method according to  claim 1 , wherein a plurality of photo-initiator moieties are covalently linked to a scaffold. 
     
     
         6 . The method according to  claim 1 , wherein the coating composition does not comprise (meth)acrylic monomers. 
     
     
         7 . The method according to  claim 1 , wherein the thermoplastic matrix polymer is selected from the group consisting of hydrophilic polyurethane polymers and amphiphilic block-copolymers. 
     
     
         8 . The method according to  claim 1 , wherein the hydrophilic polymer is a poly(ethylene oxide). 
     
     
         9 . The method according to  claim 1 , wherein the coating composition does not comprise any photopolymerizable group(s). 
     
     
         10 . The method according to  claim 1 , wherein upon irradiating the coating composition with UV or visible light, the covalently bound photo-initiator(s) generate free radicals to covalently cross-link one or more of the polymers of the coating composition via hydrogen or electron abstraction from one or more of the polymers. 
     
     
         11 . The method according to  claim 1 , wherein the covalent cross-linking between one or more of the polymers of the coating composition is not by polymerizing photopolymerizable groups.