Method and apparatus for applying coatings of molten thermoplastic material over closed pore elastomer foam substrates

Abstract

In order to make weather seals from closed cell elastomer foam material, molten plastic is extruded over a substrate of the foam material. Surface reactions during extrusion are avoided by continuously pulling the substrate through an oven chamber to degas (and remove moisture from) the material at least on its outside to a limiting thickness of the order of 10-30 mil to form a skin or crust. The extrusion of the over-coating is carried out to form a sleeve while the substrate is still hot. Since the skin is a degassed region on the outside of the foam substrate, reactions which may cause blistering and prevent the extrusion of a smooth and firmly adhering skin are avoided. The substrate material is preferably a thermosetting EPDM rubber closed cell foam, and the over coating material is a thermoplastic elastomer (TPE).

1 - 16 . (cancelled).  
     
     
         17 . Apparatus for precuring an outer layer of a body of thermosetting, closed-cell, foam elastomeric material adapted to be a substrate for a foam weather seal, so as to accept a coating of molten plastic without degassing during coating as can prevent application of a smooth, firmly adhering coating to said substrate, said apparatus comprising a chamber having driven pulleys at opposite ends thereof around which a plurality of turns of said substrate are wrapped and extend through said chamber, and means for flowing a stream of hot air through said chamber from at least one side thereof to at least one end thereof to establish temperature operative to precure said outer layer:  
     
     
         18 . The apparatus according to  claim 17 , wherein one of said pulleys receives incoming substrate to said chamber and delivers substrate outgoing from said chamber after being heated therein, and means for tensioning said substrate leaving said one pulley.  
     
     
         19 . The apparatus according to  claim 18 , wherein said tensioning means comprises a weighted vertically movable shuttle around which said outgoing substrate is guided to an extruder.  
     
     
         20 . The apparatus according to  claim 17 , further comprising a manifold, and air blower supplying air to said manifold, said manifold being disposed alongside said chamber, a plurality of heating tubes via which air is supplied to said chamber from said manifold and heated, said chamber being opened at at least one end thereof, and said heating tubes being spaced longitudinally along said chamber.  
     
     
         21 . The apparatus according to  claim 17 , further comprising a motor connected to said pulleys for simultaneously driving said pulleys.