Slide fasteners

Abstract

A slide fastener has a coating of waterproof plastics material formed by extrusion onto the closed fastener. The slide fastener comprises two woven elongate stringers, each having a series of spaced locking members which interlock when the fastener is closed, and coating which encloses the fastener and includes a longitudinally slit projection formed on each side of the locking members. The fastener has improved waterproofing as the fastener is fully enclosed by the plastics material when it is closed, and the plastics material moulds itself round both sides of the locking members. To be accompanied, when published, by FIG. 1 of the drawings.

1 . A slide fastener having two woven elongate stringers, each of said woven elongate stringers having a series of spaced locking members, therein said series of spaced locking members interlock when said fastener is closed, said fastener having a coating of waterproof plastics material, said coating being formed by extrusion onto said fastener when said fastener is closed, said coating enclosing said fastener and said coating including a longitudinally slit projection formed on each side of said locking members.  
     
     
         2 . A slide fastener according to  claim 1 , wherein each of said longitudinally slit projections has two edges on opposite sides of said longitudinal slit in said projection and at least one of said edges of one of said longitudinally slit projections is biassed towards the other edge of said projection.  
     
     
         3 . A slide fastener according to  claim 1  wherein said coating is applied by pulling said fastener through a cross-head extrusion die when said fastener is closed.  
     
     
         4 . A slide fastener according to  claim 3 , wherein each of said slits in said projections is formed by putting said fastener through a slitting tool.  
     
     
         5 . A slide fastener according to  claim 2 , wherein each of said slits in said projections is formed by putting said fastener through a slitting tool and at least one edge of one of said projections is heated locally and subsequently subjected to pressure to produce said biassing.  
     
     
         6 . A method of making a waterproof slide fastener, comprising the steps of: 
 taking a slide fastener having two woven elongate stringers, each of said stringers having a series of spaced locking members, said series of locking members interlocking when said fastener is closed and said series of spaced locking members having an upper side and a lower side;    feeding said fastener when said fastener is closed through an extruder for plastics material;    extruding a coating of waterproof plastics material onto said fastener to enclose said fastener and to provide a projection said upper side and said lower side of said locking members;    allowing said coating to cool; and    slitting each of said projections longitudinally to provide each of said projections with a slit and two edges adjacent said slit, said edges being on opposite sides of said slit.    
     
     
         7 . A method according to  claim 6  wherein said step of slitting each of said projections is performed by passing said coated fastener through a slitting tool.  
     
     
         8 . A method according to  claim 6  wherein said method includes the further step of heating at least one of said edges of at least one of said projections adjacent said slit of said projection, and applying pressure to said edge that has been heated to bias said edge towards said slit.  
     
     
         9 . A method according to  claim 8 , wherein said pressure is applied to said edge that has been heated by a roller.