Male Touch Fastener Element

Abstract

A touch fastener has a base and an array of discrete fastener elements each extending from the base and together forming with the base a contiguous mass of resin. Each discrete fastener element includes a stem rising from the base, and a head overhanging the base from a front side of the stem to a distal edge, the front side of the stem, an underside of the head, and an upper surface of the base together forming, in side profile, a generally curved retention space boundary surface such that the boundary surface forms, at its innermost extent, a retention cavity defined between curvature discontinuities spaced from both the base and the distal edge.

1 . A touch fastener comprising:
 a base; and   an array of discrete fastener elements each extending from the base and together forming with the base a contiguous mass of resin;   wherein each of the fastener elements comprises:
 a stem rising from the base; and 
 a head overhanging the base from a front side of the stem to a non-reentrant distal tip, the front side of the stem forming, in side profile, a generally curved retention space boundary surface below the tip; 
   wherein the boundary surface forms, at its innermost extent, a retention cavity defined between curvature discontinuities spaced from both the base and the distal tip.   
     
     
         2 . The touch fastener of  claim 1 , wherein at least one of the curvature discontinuities is an inflection point along the boundary surface. 
     
     
         3 . The touch fastener of  claim 1 , wherein at least one of the curvature discontinuities is a corner. 
     
     
         4 . The touch fastener of  claim 1 , wherein the retention cavity is bounded by a concave cavity wall. 
     
     
         5 . The touch fastener of  claim 4 , wherein the concave cavity wall defines a constant curvature radius. 
     
     
         6 . The touch fastener of  claim 5 , wherein the constant curvature radius is less than 20 percent of an overall height of the fastener element above the upper surface of the base. 
     
     
         7 . The touch fastener of  claim 1 , wherein the retention cavity is bounded by a concave cavity wall defining a curvature radius between about 0.001 and 0.003 inch. 
     
     
         8 . The touch fastener of  claim 1 , wherein each of the fastener elements has at least one flat side. 
     
     
         9 . (canceled) 
     
     
         10 . The touch fastener of  claim 1 , wherein each of the fastener elements comprises two distal, non-reentrant tips. 
     
     
         11 . (canceled) 
     
     
         12 . The touch fastener of  claim 1 , wherein the innermost extent of the boundary surface is disposed at an elevation above the upper surface of the base that is less than half of an overall height of the fastener element above the upper surface of the base. 
     
     
         13 . (canceled) 
     
     
         14 . The touch fastener of  claim 1 , wherein an innermost extent of the boundary surface and a forward-most portion of the distal edge tip form a line extending at between about 20 and 40 degrees to the base. 
     
     
         15 - 43 . (canceled) 
     
     
         44 . The touch fastener of  claim 1 , wherein the generally curved retention space boundary surface extends from the upper surface of the base to an underside surface of the head. 
     
     
         45 . The touch fastener of  claim 1 , wherein the curvature discontinuities between which the retention cavity is defined are both disposed closer to the upper surface of the base than is the distal tip. 
     
     
         46 . The touch fastener of  claim 1 , wherein the stem has a flat side extending generally perpendicular to the base, and wherein the retention space boundary surface defines an edge with the flat side of the stem.