Touch fastener element loop retention

Abstract

A male touch fastener component having a sheet-form base and an array of molded fastener elements having stems and heads having lower surfaces forming an arched crook for retaining loops. The crooks have particularly high crook angles, such that a maximum side angle measured about the crook from a line normal to the forward edge of the stem at an elevation from the base corresponding to a lowermost extent of the tip, to a normal to the lower head surface, is greater than about 180 degrees.

1 . A touch fastener component having a sheet-form base and an array of fastener elements, each fastener element comprising: 
 a stem extending outwardly from and integrally with the sheet-form base, and    a head extending from a distal end of the stem to a tip to overhang a forward edge of the stem, the head having a lower surface forming an arched crook for retaining loops;    wherein the crook defines an under crook angle, measured about the crook in side view from a line normal to the forward edge of the stem at an elevation from the base corresponding to a lowermost extent of the tip, to a normal to the lower head surface, that is greater than about 180 degrees.    
   
   
       2 . The touch fastener component of  claim 1  wherein each fastener element has multiple heads extending in different directions and forming separate crooks.  
   
   
       3 . The touch fastener component of  claim 2  wherein each fastener element has two heads extending in essentially opposite directions.  
   
   
       4 . The touch fastener component of  claim 3  wherein each fastener element defines an upper well between the two oppositely-directed heads, the well extending down to a height, measured perpendicularly from the base, of at least about 70 percent of the overall height of one of the two oppositely-directed heads.  
   
   
       5 . The touch fastener component of  claim 3  wherein each fastener element has an overall length between opposite extents of the oppositely-directed heads, measured parallel to the base, of at least 1.8 times the overall height of the fastener element.  
   
   
       6 . The touch fastener component of  claim 1  wherein a ratio of an overall height of the crook, measured perpendicular to the sheet-form base from a lowermost extent of the tip to an uppermost extent of the crook, to an entrance height measured perpendicular to the sheet-form base below a lowermost extent of the tip, is greater than 0.6.  
   
   
       7 . The touch fastener component of  claim 1  wherein the head has an overall thickness, measured parallel to the base and perpendicular to a plane of the crook, that is greater than an entrance height measured perpendicular to the sheet-form base below a lowermost extent of the tip.  
   
   
       8 . The touch fastener component of  claim 1  wherein the head and stem form a unitary molded structure.  
   
   
       9 . The touch fastener component of  claim 1  wherein the head has a surface of resin cooled against a mold surface.  
   
   
       10 . The touch fastener component of  claim 1  wherein the stem has opposing surfaces defined by severed resin.  
   
   
       11 . The touch fastener component of  claim 1  wherein the stem and head have side surfaces lying in parallel planes.  
   
   
       12 . The touch fastener component of  claim 1  wherein the forward edge of the stem extends at an inclination angle of between about 20 and 30 degrees with respect to a normal to the base.  
   
   
       13 . The touch fastener component of  claim 12  wherein the inclination angle is about 23 degrees.  
   
   
       14 . The touch fastener component of  claim 1  wherein each fastener element has an overall height of between about 10 and 50 millimeters.  
   
   
       15 . The touch fastener component of  claim 14  wherein each fastener element has an overall height of between about 20 and 30 millimeters.  
   
   
       16 . The touch fastener component of  claim 1  wherein each fastener element head has an overall height of between about 10 and 20 millimeters.  
   
   
       17 . The touch fastener component of  claim 1  wherein each fastener element crook defines an overall crook height, measured perpendicular to the sheet-form base from a lowermost extent of the tip to an uppermost extent of the crook, of at least 6.0 millimeters.  
   
   
       18 . The touch fastener component of  claim 1  further comprising a backing material laminated to a side of the base opposite the fastener elements.  
   
   
       19 . The touch fastener component of  claim 1  wherein the fastener elements are arranged in a density of at least 350 fastener elements per square inch of the base.  
   
   
       20 . The touch fastener component of  claim 1  wherein the fastener elements together cover at least 20 percent of an overall surface area of the base from which the fastener elements extend.  
   
   
       21 . The touch fastener component of  claim 1  wherein the under crook angle is at least about 190 degrees.  
   
   
       22 . The touch fastener component of  claim 21  wherein the under crook angle is about 200 degrees.  
   
   
       23 . A method of forming a touch fastener component having a sheet-form base and an array of fastener elements, the method comprising: 
 introducing molten resin to a peripheral surface of a rotating mold roll defining an array of inwardly-extending cavities each including 
 a stem region extending inwardly from the peripheral surface, and  
 a head region extending laterally from a distal end of the stem region to a blind tip, the head region bounded by an outer surface forming a crook inward of a forward edge of the stem region,  
 the crook defining an under crook angle, measured about the crook in side view from a line normal to the forward edge of the stem region at a mold roll radius to the tip, to a normal to the crook-forming outer surface, that is greater than about 180 degrees;  
   applying sufficient pressure to force the resin into the cavities to mold an array of fastener elements, while forming a sheet of the resin on the peripheral surface of the mold roll;    cooling the resin in the cavities; and then    stripping the sheet of resin from the surface of the mold roll, thereby pulling heads of the fastener elements formed in the head regions of the cavities through the stem regions of the cavities to remove the fastener elements from the cavities.