Split hook fastener

Abstract

The present invention provides a method for forming preferably a unitary polymeric hook fastener comprising a flexible backing, and a multiplicity of spaced hook elements projecting from the upper surface of the unitary backing. The hook elements each comprise a stem portion attached at one end to the backing, and a head portion at the end of the stem portion opposite the backing. The head portion projects in different directions for some adjacent hook members which adjacent hook members each have a flat face which flat faces are mutually opposing in face to face relation.

1 . A hook fastener comprising a thermoplastic base layer with integral upstanding hook members having stem portions and head portions at least some of the hook members having at least one flat face and an opposing nonflat face with at least some of the hook members having overhanging portions extending beyond the stem portions.  
     
     
         2 . The hook fastener of  claim 1  wherein the hook members having a flat face are in opposing face to face relation with the flat face of another hook member having a flat face.  
     
     
         3 . The hook fastener of  claim 1  wherein the film backing is oriented in at least one direction.  
     
     
         4 . The hook fastener of  claim 3  wherein the film backing has a thickness of from 25 to 250 μm.  
     
     
         5 . The hook fastener of  claim 3  wherein the film backing has a thickness of from 25 to 150 μm.  
     
     
         6 . The hook fastener of  claim 1  wherein the overhanging portions extend from 0.01 to 0.3 mm.  
     
     
         7 . The hook fastener of  claim 6  wherein the overhanging portions extend from 0.02 to 0.25 mm.  
     
     
         8 . The hook fastener of  claim 6  wherein the overhanging portions extend from 0.02 to 0.2 mm.  
     
     
         9 . The hook fastener of  claim 1  wherein the hook members have a height of from 0.1 to 2 mm.  
     
     
         10 . The hook fastener of  claim 1  wherein the hook members and the hook elements on the backing have a density of from 25 to 500 per square centimeter.  
     
     
         11 . The hook fastener of  claim 1  wherein at least a portion of the hook engaging portion extends at an angle of from 10 to 90° from a flat face of the hook member.  
     
     
         12 . The hook fastener of  claim 1  wherein at least a portion of the hook engaging portion extends at an angle (α) of from 1 to 890 from a flat face of the hook member.  
     
     
         13 . The hook fastener of  claim 1  wherein at least a portion of the hook engaging portion extends at an angle (α) of from 5 to 85° from a flat face of the hook member.  
     
     
         14 . The hook fastener of  claim 1  wherein the hook fastener includes hook elements without flat faces.  
     
     
         15 . The hook fastener of  claim 14  wherein the hook members having flat faces comprise at least 50 percent of the hook structures.  
     
     
         16 . The hook fastener of  claim 15  wherein the hook members having flat faces comprise at least 90 percent of the hook structures.  
     
     
         17 . A method of forming a hook fastener comprising providing a hook fastener strip having a thermoplastic base layer with integral upstanding hook elements having stem portions and head portions with loop engaging overhangs, cutting at least some of the hook elements along the head portion and down to the stem portion substantially to the base layer and orienting the base layer so as to separate the cut hook elements.  
     
     
         18 . The hook fastener of  claim 17  wherein the hook members having a flat face are in opposing face to face relation with the flat face of another hook member having a flat face.  
     
     
         19 . The hook fastener of  claim 17  wherein the film backing is oriented.  
     
     
         20 . The hook fastener of  claim 19  wherein the film backing has a thickness of from 25 to 250 μm.  
     
     
         21 . The hook fastener of  claim 19  wherein the film backing has a thickness of from 50 to 150 μm.  
     
     
         22 . The hook fastener of  claim 17  wherein the overhanging portions extend 0.01 to 0.3 mm.  
     
     
         23 . The hook fastener of  claim 22  wherein the overhanging portions extend 0.02 to 0.25 mm.  
     
     
         24 . The hook fastener of  claim 22  wherein the overhanging portions extend 0.02 to 0.2 mm.  
     
     
         25 . The hook fastener of  claim 17  wherein the hook members have a height of from 0.1 to 2 mm.  
     
     
         26 . The hook fastener of  claim 17  wherein the hook members and hook elements on the backing have a density of from 25 to 500 per square centimeter.  
     
     
         27 . The hook fastener of  claim 17  wherein at least a portion of the hook engaging portion extends at an angle (α) of from 1° to 90° from a flat face of the hook member.  
     
     
         28 . The hook fastener of  claim 17  wherein at least a portion of the hook engaging portion extends at an angle (α) of from 1 to 89° from a flat face of the hook member.  
     
     
         29 . The hook fastener of  claim 17  wherein at least a portion of the hook engaging portion extends at an angle (α) of from 5 to 85° from a flat face of the hook member.  
     
     
         30 . The hook fastener of  claim 17  wherein the hook fastener includes hook elements without flat faces.  
     
     
         31 . The hook fastener of  claim 30  wherein the hook members having flat faces comprise at least 50 percent of the hook structures.  
     
     
         32 . The hook fastener of  claim 31  wherein the hook members having flat faces comprise at least 90 percent of the hook structures.