Removable, water-whitening resistant pressure sensitive adhesives

Abstract

Removable pressure sensitive adhesive compositions having enhanced resistance to water-whitening comprising a crosslinked aqueous emulsion polymer are disclosed. The crosslinked aqueous emulsion polymer comprises (a) at least one hydrophobic monomer; (b) greater than 1 wt. % of at least one hydrophilic monomer; (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group; (d) optionally at least one partially hydrophilic monomer; and (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant; wherein the crosslinked aqueous emulsion polymer is crosslinked with an effective amount of at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of the crosslinked aqueous emulsion polymer is less than about 400

1 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) greater than 1 wt. % of at least one hydrophilic monomer;    (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    further comprising a non-polymerizable surfactant.    
   
   
       2 . The composition of  claim 1  wherein said non-polymerizable surfactant is an ionic surfactant.  
   
   
       3 . The composition of  claim 1  wherein said monomer (d) is selected from methyl acrylate, methyl methacrylate, ethyl acrylate, or mixtures thereof.  
   
   
       4 . The composition of  claim 3  wherein said monomer (d) is selected from methyl acrylate, ethyl acrylate, or mixtures thereof.  
   
   
       5 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) greater than 1 wt. % of at least one hydrophilic monomer;    (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    wherein said polymerizable surfactant has a hydrophilic portion selected from a sulfonate allyl amine moiety, a sulfate allyl amine moiety, or a phosphate allyl amine moiety, and a hydrophobic portion selected from —R, or a group having the formula RO—(CH 2 CH 2 O) n —; wherein R is an alkyl group or an alkyl-substituted phenyl group wherein the alkyl group has 1 to 20 carbon atoms, and n is an integer from 2 to 100; and    wherein n is an integer from 2 to 15.    
   
   
       6 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) greater than 1 wt. % of at least one hydrophilic monomer;    (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    wherein said polymerizable surfactant is an allyl amine salt of an alkyl ether sulfate having the formula                          wherein R 2  is an alkyl group having 1 to 20 carbon atoms, n is an integer from 2 to 100, and X +  is selected from  + NH 3 ,  +NH   2 R 4 , or  + NHR 4 R 5 , wherein R 4  and R 5  are independently selected from C 1 -C 4  alkyl or hydroxyalkyl groups.    
   
   
       7 . The composition of  claim 6  wherein n is an integer from 2 to 15.  
   
   
       8 . The composition of  claim 7  wherein said polymerizable surfactant is an allyl amine salt of laureth sulfate.  
   
   
       9 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) greater than 1 wt. % of at least one hydrophilic monomer;    (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    wherein said polymerizable surfactant is an allyl amine salt of a phosphate ester having the formula                          wherein R 3  is an alkyl or alkyl-substituted phenyl group wherein the alkyl group has 1 to 20 carbon atoms, n is an integer from 2 to 100, and X +  is selected from  + NH 3 ,  + NH 2 R 4 , or  + NHR 4 R 5 , wherein R 4  and R 5  are independently selected from C 1 -C 4  alkyl or hydroxyalkyl groups.    
   
   
       10 . The composition of  claim 9  wherein n is an integer from 2 to 15.  
   
   
       11 . The composition of  claim 10  wherein said polymerizable surfactant is an allyl amine salt of nonylphenol ethoxylate (9 moles EO) phosphate ester.  
   
   
       12 . The composition of  claim 1  wherein said polymerizable surfactant is an allyl amine salt of a sulfate having the formula  
       R 6 —SO 3   −+ X—CH 2 —CH═CH 2    wherein R 6  is an alkyl group having 6 to 20 carbon atoms, and X +  is selected from  + NH 3 ,  + NH 2 R 4 , or  + NHR 4 R 5 , wherein R 4  and R 5  are independently selected from C 1 -C 4  alkyl or hydroxyalkyl groups.    
   
   
       13 . The composition of  claim 12  wherein R 6  is an alkyl group having 10 to 18 carbon atoms.  
   
   
       14 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) greater than 1 wt. % of at least one hydrophilic monomer;    (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    wherein said polymerizable surfactant is a substituted phenyl compound having the formula                          wherein R 7  is an alkyl, alkenyl or aralkyl group containing 6 to 18 carbon atoms; R 8  is a hydrogen atom or an alkyl, alkenyl or aralkyl group containing 6 to 18 carbon atoms; R 9  is a hydrogen atom or a propenyl group; A is an unsubstituted or substituted alkylene group containing 2 to 4 carbon atoms; n is an integer of 1 to about 200; and M is an alkali metal, an ammonium ion, or an alkanolamine residue.    
   
   
       15 . The composition of  claim 14  wherein said polymerizable surfactant is a substituted phenyl compound having the formula  
     
       
         
         
             
             
         
       
     
   
   
       16 . The composition of  claim 15  wherein R 7  is alkyl, A is ethylene, and M is alkali metal or ammonium.  
   
   
       17 . The composition of  claim 16  wherein R 7  is nonyl, n is about 10 to about 30, and M is ammonium.  
   
   
       18 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) greater than 1 wt. % of at least one hydrophilic monomer;    (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    wherein said polymerizable surfactant is a polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salt having the formula:                          wherein R 10  is an alkyl group containing 8 to 30 carbon atoms; R 11  is hydrogen or methyl; A is an unsubstituted or substituted alkylene group having 2 to 4 carbon atoms; n is 0 or an integer of 1 to about 200; and M is an alkali metal, an ammonium ion, or an alkanolamine residue.    
   
   
       19 . The composition of  claim 18  wherein said polymerizable surfactant is a polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salt having the formula:  
     
       
         
         
             
             
         
       
       wherein R 10  is an alkyl group containing 8 to 14 carbon atoms; and n is an integer of 1 to about 200.  
     
   
   
       20 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) greater than 1 wt. % of at least one hydrophilic monomer;    (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    further comprising a non-polymerizable surfactant.    
   
   
       21 . The composition of  claim 20  wherein said non-polymerizable surfactant is an ionic surfactant.  
   
   
       22 . The composition of  claim 21  wherein said ionic surfactant is an anionic surfactant selected from alkyl.aryl sulfonates, alkyl sulfates, sulfates of ethoxylated alcohols, sulfates and sulfonates of ethoxylated alkylphenols, sulfosuccinates, diphenyl sulfonates, or mixtures thereof.  
   
   
       23 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) about 70 to about 90 wt. % of at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) about 2 to about 10 wt. % of at least one hydrophilic monomer;    (c) greater than 3 to about 20 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group;    (d) 0 to about 45 wt. % of at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and    (e) about 0.1 to about 5 wt. % of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-l-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof;    wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) and the wt. % of polymerizable surfactant (e) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm;    further comprising a non-polymerizable surfactant.    
   
   
       24 . The composition of  claim 23  wherein said non-polymerizable surfactant is an ionic surfactant.  
   
   
       25 . The composition of  claim 24  wherein said ionic surfactant is an anionic surfactant selected from alkyl aryl sulfonates, alkyl sulfates, sulfates of ethoxylated alcohols, sulfates and sulfonates of ethoxylated alkylphenols, sulfosuccinates, diphenyl sulfonates, or mixtures thereof.  
   
   
       26 . A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: 
 (a) about 70 to about 90 wt. % of at least one hydrophobic monomer selected from butyl acrylate, 2-ethylhexyl acrylate, mixtures of butyl acrylate and 2-ethylhexyl acrylate, or a mixture of styrene and at least one of butyl acrylate and 2-ethylhexyl acrylate, wherein when styrene is present, said styrene is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture;    (b) about 2 to about 10 wt. % of at least one hydrophilic monomer selected from acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, or mixtures thereof;    (c) about 3.5 to about 20 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group selected from diacetone acrylamide, diacetone acrylate, acrolein, or mixtures thereof;    (d) 0 to about 25 wt. % of at least one partially hydrophilic monomer selected from methyl acrylate, ethyl acrylate, or mixtures thererof;    (e) about 0.1 to about 5 wt. % of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof; and    (f) about 0.1 to about 2 wt. % of at least one non-polymerizable ionic surfactant;    wherein said crosslinked aqueous emulsion polymer is crosslinked with an effective amount of at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d), the wt. % of polymerizable surfactant (e), and the wt. % of the non-polymerizable surfactant (f) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm.    
   
   
       27 . The composition of  claim 26  wherein said polyhydrazide is selected from dihydrazides, trihydrazides, tetrahydrazides, bis-semicarbizides, aromatic polycarboxylic polyhydrazides, or mixtures thereof.  
   
   
       28 . The composition of  claim 27  wherein said polyhydrazide is selected from dihydrazides represented by the formula  
     
       
         
         
             
             
         
       
       wherein R 10  is selected from a linear or branched divalent alkylene group having 0 to about 10 carbon atoms, preferably 2 to 10 carbon atoms, a divalent alicyclic group having 4 to about 8 carbon atoms, a divalent aromatic ring, or  
       
         
           
           
               
               
           
         
       
       wherein the rings are alicyclic or aromatic and X is selected from —O—, —S—, —SO 2 —, or —C(O)—; bis-semicarbizides represented by the formula  
       
         
           
           
               
               
           
         
       
       wherein R 9  is a divalent straight-chain or branched alkylene group having 2 to about 7 carbon atoms or a divalent carbocyclic group having 6 to 8 carbon atoms; trihydrazides represented by the formula  
       
         
           
           
               
               
           
         
       
       wherein R 5 -R 8  are independently selected from H or OH, p is an integer from 0 to 3, and q is an integer from 2 to 8, provided p+q≦8 and p<q; or mixtures thereof.  
     
   
   
       29 . The composition of  claim 28  wherein said polyhydrazide is selected from oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide,-carbonic acid dihydrazide, phthalic acid dihydrazide, terephthalic acid dihydrazide, isophthalic acid dihydrazide, 1,2,4-butanetricarbohydrazide, 1,1,4-butanetricarbohydrazide, 1,2,5-pentanetricarbohydrazide, 1,3,6-hexane-tricarbohydrazide, 1,3,7-heptanetricarbohydrazide, 1-hydroxy-1,2,4-butanetricarbohydrazide, or mixtures thereof.  
   
   
       30 . The composition of  claim 27  wherein said polyhydrazide is an aliphatic dicarboxylic acid dihydrazide.  
   
   
       31 . The composition of  claim 30  wherein said polyhydrazide is adipic acid dihydrazide.