Fasteners and methods of making fasteners

Abstract

A method of forming a fastener is provided, including (a) forming, from a thermoformable material, a preform product having a sheet-form base and an array of preform stems integrally molded with and extending from the base to corresponding terminal ends; (b) heating the terminal ends of the stems to a predetermined softening temperature, while maintaining the sheet-form base and a lower portion of each stem at a temperature lower than the softening temperature; and (c) contacting the terminal ends with a contact surface that is at a predetermined forming temperature, lower than the softening temperature, to deform the terminal ends to form heads therefrom that overhang the sheet-form base. Fasteners and other methods of forming them are also provided.

What is claimed is:  
     
         1 . A method of forming a fastener, comprising: 
 (a) forming, from a thermoformable material, a preform product having a sheet-form base and an array of preform stems integrally molded with and extending from the base to corresponding terminal ends;    (b) heating the terminal ends of the stems to a predetermined softening temperature, while maintaining the sheet-form base and a lower portion of each stem at a temperature lower than the softening temperature; and    (c) contacting the terminal ends with a contact surface that is at a predetermined forming temperature, to deform the terminal ends to form heads therefrom that overhang the sheet-form base.    
     
     
         2 . The method of  claim 1  wherein said forming temperature is sufficiently low that said thermoformable material does not adhere to the contact surface.  
     
     
         3 . The method of  claim 1  wherein said forming temperature is lower than the softening temperature of the thermoformable material.  
     
     
         4 . The method of  claim 1  wherein said contact surface comprises the cylindrical surface of a roll.  
     
     
         5 . The method of  claim 1  wherein said contact surface is cooled to maintain said forming temperature during step (c).  
     
     
         6 . The method of  claim 1  wherein, in step (c), the heads that are formed are substantially disc-shaped.  
     
     
         7 . The method of  claim 6  wherein the thickness of each disc-shaped head is from about 5 to 15% of the equivalent diameter of the disc.  
     
     
         8 . The method of  claim 1  wherein, in step (c), the heads that are formed are substantially mushroom-shaped.  
     
     
         9 . The method of  claim 8  wherein said head has a substantially dome-shaped surface overhanging said base.  
     
     
         10 . The method of  claim 1  wherein step (a) comprises molding said stems in molding cavities in a mold roll.  
     
     
         11 . The method of  claim 1  wherein, in step (b), the region extends from the terminal end towards the base a distance equal to from about 15 to 25% of the total distance from the terminal end to the base.  
     
     
         12 . The method of  claim 1  or  5  wherein said contact surface has a surface finish selected from the group consisting of dimpled, smooth, textured, and combinations thereof.  
     
     
         13 . The method of  claim 12  wherein said surface finish comprises dimples and said contact surface includes a density of dimples per unit area of the contact surface that is greater than or equal to the density of stems per unit area of the base.  
     
     
         14 . The method of  claim 13  wherein, during step (c), said dimples are in at least partial registration with said stems.  
     
     
         15 . A method of forming a fastener, comprising: 
 (a) forming a plurality of stems, extending from a common base to a terminal end, from a thermoformable material;    (b) heating a region of the stems adjacent the terminal ends to a predetermined softening temperature, to soften the material in the region, while maintaining the remaining portion of the stems at a temperature lower than the softening temperature; and    (c) contacting the terminal ends with a contact surface to form heads at the terminal end of said stems, at least a portion of the contact surface having a sufficiently rough texture to impart a loop-engaging surface roughness to at least a portion of said heads.    
     
     
         16 . The method of  claim 15  wherein said contact surface comprises the cylindrical surface of a roll.  
     
     
         17 . The method of  claim 15  wherein said contact surface has a sandpaper-like texture.  
     
     
         18 . The method of  claim 15  wherein said contact surface has a rugosity of about 10 to 200 microns.  
     
     
         19 . The method of  claim 17  or  18  wherein said contact surface defines a plurality of dimples.  
     
     
         20 . The method of  claim 19  wherein said contact surface includes a density of dimples per unit area of the contact surface that is greater than or equal to the density of stems per unit area of the base.  
     
     
         21 . The method of  claim 15  wherein the surface roughness imparted to the heads is sufficient to increase the peel strength of the fastener by from about 10 to 100%.  
     
     
         22 . A fastener element comprising: 
 an elongated stem extending and molded integrally with a substantially planar base; and    a head disposed at a terminal end of the stem, at least a portion of said head having a rough surface having a sandpaper-like surface texture.    
     
     
         23 . The fastener element of  claim 22  wherein said rough surface has a surface roughness of from about 10 to 200 microns.  
     
     
         24 . The fastener element of  claim 22  wherein said rough surface has sufficient surface roughness to increase the peel strength of the fastener by from about 10 to 100%.  
     
     
         25 . The fastener element of  claim 22  wherein said head is substantially disc-shaped.  
     
     
         26 . The fastener element of  claim 22  wherein said head is substantially mushroom-shaped.  
     
     
         27 . The fastener element of  claim 26  wherein said head includes a substantially planar surface-overhanging said base.  
     
     
         28 . A fastener element comprising: 
 an elongated stem extending and molded integrally with a substantially planar base; and    a head disposed at a terminal end of the stem, said. head being substantially disc-shaped and having a thickness equal to from about 5 to 15% of the equivalent diameter of the disc.    
     
     
         29 . The fastener element of  claim 28  wherein said head includes a domed portion.  
     
     
         30 . The fastener element of  claim 28  wherein said head is wavy, pyramidal or mushroom-shaped.  
     
     
         31 . The fastener element of  claim 28  wherein said head includes a sandpaper-like surface.  
     
     
         32 . An attachment strip for attaching a mesh screen to a surface, comprising: 
 (a) a substantially planar base;    (b) a plurality of elongated stems extending from said base; and    (c) a plurality of heads, each head being disposed at a terminal end of one of said stems, at least a portion of said heads having a rough surface having a sandpaper-like surface texture.    
     
     
         33 . An attachment strip for attaching a mesh screen to a surface, comprising: 
 (a) a substantially planar base;    (b) a plurality of elongated stems extending from said base; and    (c) a plurality of heads, each head being disposed at a terminal end of one of said stems, and each head being substantially disc-shaped and having a thickness equal to from about 5 to 15% of the equivalent diameter of the disc.