Post-curable pressure-sensitive adhesive

Abstract

The present disclosure is directed to a curable precursor of a pressure sensitive adhesive comprising: a) a (co)polymeric material comprising the reaction product of a (co)polymerizable material comprising a (meth)acrylate ester monomer; and optionally, a co-monomer having an ethylenically unsaturated group and which is different from the (meth)acrylate ester monomer; b) a polyfunctional aziridine curing agent; and c) an acid generating agent. The present disclosure is also directed to a method of manufacturing such pressure sensitive adhesives and uses thereof.

1 . A curable precursor of a pressure sensitive adhesive comprising:
 a) a (co)polymeric material comprising the reaction product of a (co)polymerizable material comprising a (meth)acrylate ester monomer; and optionally, a co-monomer having an ethylenically unsaturated group, the co-monomer being a non-acid functional polar monomer;   b) a polyfunctional aziridine curing agent comprising at least two aziridine functional groups; and   c) an acid generating agent selected from the group consisting of thermal acid generating agents, photo acid generating agents, and any combinations or mixtures thereof; and wherein the photo acid generating agent is selected from the group consisting of ionic salts of organometallic complexes, iodonium or sulfonium salts and any combinations or mixtures thereof.   
     
     
         2 . A curable precursor according to  claim 1 , wherein the polyfunctional aziridine curing agent comprises two or three aziridine functional groups. 
     
     
         3 . A curable precursor according to  claim 1 , wherein the polyfunctional aziridine curing agent has the following formula: 
       
         
           
           
               
               
           
         
         wherein 
         R 1  is a (hetero)hydrocarbyl group; 
         R 2  is an H, C 1 -C 12  alkyl group, or C 6 -C 12  aromatic group; 
         x is 0, 1 or 2; and 
         y is at least 1. 
       
     
     
         4 . A curable precursor according to  claim 1 , wherein the polyfunctional aziridine curing agent has the following formula: 
       
         
           
           
               
               
           
         
         wherein 
         R 4  is a (hetero)hydrocarbyl group having a valency of y; 
         R 5  and R 6  are independently (hetero)hydrocarbyl groups; 
         R 2  is an H, C 1 -C 12  alkyl group, or C 6 -C 12  aromatic group; 
         y is at least 1; 
         x is 0, 1 or 2; and 
         each of a and b are independently 0 to 6. 
       
     
     
         5 . (canceled) 
     
     
         6 . A curable precursor according to  claim 1 , wherein the acid generating agent is a thermal acid generating agent selected from the group consisting of quarternary blocked superacids, amine blocked superacids, and any combinations or mixtures thereof. 
     
     
         7 . (canceled) 
     
     
         8 . A curable precursor according to  claim 1 , wherein the non-acid functional polar monomer has a nitrogen-containing group or a salt thereof. 
     
     
         9 . A curable precursor according to  claim 8 , wherein the nitrogen-containing group is selected from secondary amido groups and tertiary amido groups. 
     
     
         10 . A curable precursor according to  claim 1 , wherein the optional co-monomer having an ethylenically unsaturated group is N-vinyl caprolactam. 
     
     
         11 . A curable precursor according to  claim 1 , wherein the (co)polymeric material comprising the reaction product of a (co)polymerizable material comprising a (meth)acrylate ester monomer, is free of acid functional monomers. 
     
     
         12 . A curable precursor according to  claim 1 , comprising:
 a) 100 parts by weight of a (co)polymeric material comprising the reaction product of a (co)polymerizable material comprising a (meth)acrylate ester monomer; and optionally, a co-monomer having an ethylenically unsaturated group, the co-monomer being a non-acid functional polar monomer;   b) from 0.1 to 30 parts by weight of a polyfunctional aziridine curing agent comprising at least two aziridine functional groups;   c) from 0.01 to 10 parts by weight of an acid generating agent selected from the group consisting of thermal acid generating agents, photo acid generating agents, and any combinations or mixtures thereof; and wherein the photo acid generating agent is selected from the group consisting of ionic salts of organometallic complexes, iodonium or sulfonium salts and any combinations or mixtures thereof; and   d) optionally, from 1 to 20 parts by weight of a filler material, preferably hollow glass microspheres.   
     
     
         13 . A cured pressure sensitive adhesive obtainable by curing the curable precursor according to  claim 1 , wherein the curing step is performed by allowing acid to be released into the curable precursor of a pressure sensitive adhesive. 
     
     
         14 . A cured pressure sensitive adhesive according to  claim 13 , wherein the curing step is performed by subjecting the curable precursor of a pressure sensitive adhesive to a triggering energy sufficient to allow the acid generating agent to release acid into the curable precursor of a pressure sensitive adhesive, and wherein the triggering energy is thermal energy or actinic radiation. 
     
     
         15 . A method of applying a pressure sensitive adhesive to a substrate, comprising the steps of:
 a) providing a curable precursor of a pressure sensitive adhesive comprising:
 i. a (co)polymeric material comprising the reaction product of a (co)polymerizable material comprising a (meth)acrylate ester monomer; and optionally, a co-monomer having an ethylenically unsaturated group, the co-monomer being a non-acid functional polar monomer; 
 ii. a polyfunctional aziridine curing agent comprising at least two aziridine functional groups; and 
 iii. optionally, an acid generating agent selected from the group consisting of thermal acid generating agents, photo acid generating agents, and any combinations or mixtures thereof; and wherein the photo acid generating agent is selected from the group consisting of ionic salts of organometallic complexes, iodonium or sulfonium salts and any combinations or mixtures thereof; 
   b) applying the curable precursor of a pressure sensitive adhesive to at least part of the surface of the substrate; and   c) curing the curable precursor of a pressure sensitive adhesive by allowing acid to be released into it.   
     
     
         16 . A method of applying a pressure sensitive adhesive to a substrate, comprising the steps of:
 a) providing a curable precursor of a pressure sensitive adhesive comprising:
 i. a (co)polymeric material comprising the reaction product of a (co)polymerizable material comprising a (meth)acrylate ester monomer; and optionally, a co-monomer having an ethylenically unsaturated group, the co-monomer being a non-acid functional polar monomer and which is different from the (meth)acrylate ester monomer; 
 ii. a polyfunctional aziridine curing agent comprising at least two aziridine functional groups; and 
 iii. optionally, an acid generating agent selected from the group consisting of thermal acid generating agents, photo acid generating agents, and any combinations or mixtures thereof; and wherein the photo acid generating agent is selected from the group consisting of ionic salts of organometallic complexes, iodonium or sulfonium salts and any combinations or mixtures thereof; 
   b) partially curing the curable precursor of a pressure sensitive adhesive by allowing acid to be released into it;   c) applying the partially cured pressure sensitive adhesive to at least part of the surface of the substrate; and   d) allowing the partially cured pressure sensitive adhesive to fully cure onto the substrate.   
     
     
         17 . A method according to  claim 16 , whereby the curing step is performed by subjecting the curable precursor of a pressure sensitive adhesive to a triggering energy sufficient to allow the acid generating agent to release acid into the curable precursor of a pressure sensitive adhesive, and wherein the triggering energy is thermal energy or actinic radiation. 
     
     
         18 . A method according to  claim 16 , whereby the curing step is performed by contacting the curable precursor of a pressure sensitive adhesive with a source of acid. 
     
     
         19 . (canceled) 
     
     
         20 . (canceled)