Heat-activatable adhesive

Abstract

Heat-activatable adhesives comprise a semi-crystalline polymer. The semi-crystalline polymer comprises alkyl (meth)acrylate monomer units having an alkyl group that contains at least about 20 carbon atoms, alkyl (meth)acrylate monomer units having an alkyl group that contains from about 4 to about 12 carbon atoms, and optionally ethylenically-unsaturated non-acidic polar monomer units. Methods for making heat-activatable adhesives and articles therefrom are also included.

1 . A heat-activatable adhesive article comprising: 
 a substrate having a major surface; and    a layer of heat-activatable adhesive comprising a semi-crystalline polymer and supported on at least a portion of the major surface, wherein the semi-crystalline polymer comprises: 
 (a) about 20 to about 70 percent by weight of alkyl (meth)acrylate monomer units having an alkyl group that contains at least about 20 carbon atoms;  
 (b) about 80 to about 30 percent by weight of alkyl (meth)acrylate monomer units having an alkyl group that contains from about 4 to about 12 carbon atoms; and  
 (c) ethylenically-unsaturated non-acidic polar monomer units in an amount of less than about 20 percent by weight, wherein the polymer has an activation temperature of at least about 40 degrees Celsius.  
   
   
   
       2 . The heat-activatable adhesive article of  claim 1 , wherein the polymer is crosslinked.  
   
   
       3 . The heat-activatable adhesive article of  claim 1 , wherein the semi-crystalline polymer comprises about 40 to about 60 percent by weight of alkyl (meth)acrylate monomer units having an alkyl group that contains at least 18 carbon atoms.  
   
   
       4 . The heat-activatable adhesive article of  claim 1 , wherein the semi-crystalline polymer comprises about 60 to about 40 percent by weight of alkyl (meth)acrylate monomer units having an alkyl group that contains from about 4 to about 12 carbon atoms.  
   
   
       5 . The heat-activatable adhesive article of  claim 1 , wherein the ethylenically-unsaturated non-acidic polar monomer units comprise are selected from the group consisting of N-vinyl lactams, acrylamides, and combinations thereof.  
   
   
       6 . The heat-activatable adhesive article of  claim 1 , wherein the semi-crystalline polymer comprises about 30 to about 70 percent by weight of alkyl (meth)acrylate monomer units having an alkyl group that contains at least 22 carbon atoms.  
   
   
       7 . The heat-activatable adhesive article of  claim 1 , wherein the semi-crystalline polymer comprises about 30 to about 70 percent by weight of behenyl acrylate.  
   
   
       8 . The heat-activatable adhesive article of  claim 1 , wherein the semi-crystalline polymer comprises about 60 to about 40 percent by weight of alkyl (meth)acrylate monomer units having an alkyl group that contains from about 4 to about 12 carbon atoms.  
   
   
       9 . The heat-activatable adhesive article of  claim 1 , wherein the semi-crystalline polymer comprises about 55 to about 45 percent by weight of alkyl (meth)acrylate monomer units having an alkyl group that contains from about 4 to about 12 carbon atoms.  
   
   
       10 . The heat-activatable adhesive article of  claim 1 , wherein the ethylenically-unsaturated non-acidic polar monomer units are present in an amount of less than about 10 percent by weight.  
   
   
       11 . The heat-activatable adhesive article of  claim 1 , wherein the ethylenically-unsaturated non-acidic polar monomer units are present in an amount of less than about 5 percent by weight.  
   
   
       12 . The heat-activatable adhesive article of  claim 2 , wherein the semi-crystalline polymer comprises less than about one percent by weight of crosslinking monomer units.  
   
   
       13 . The heat-activatable adhesive of  claim 1 , wherein the activation temperature is at least about 60 degrees Celsius.  
   
   
       14 . The heat-activatable adhesive of  claim 1 , wherein the activation temperature is less than about 100 degrees Celsius.  
   
   
       15 . The heat-activatable adhesive article of  claim 1 , wherein the adhesive has a crystalline content by weight of from about 10 to about 30 percent.  
   
   
       16 . The heat-activatable adhesive article of  claim 1 , wherein the adhesive has a crystalline content by weight of from about 15 to about 25 percent.  
   
   
       17 . The heat-activatable adhesive article of  claim 1 , wherein the substrate is a film.  
   
   
       18 . The heat-activatable adhesive article of  claim 1 , wherein the substrate is selected from the group consisting of a sheet and a strip.  
   
   
       19 . The heat-activatable adhesive article of  claim 1 , wherein the substrate comprises a thermoplastic polymer.  
   
   
       20 . The heat-activatable adhesive article of  claim 1 , wherein the substrate comprises paper having a release coating thereon.