Aqueous polymer dispersion

Abstract

The present invention provides an aqueous polymer dispersion and an aqueous coating composition comprising such aqueous polymer dispersion and providing coatings with improved early water blister resistance as well as satisfactory water streaking resistance and good durability properties.

What is claimed is: 
     
         1 . An aqueous polymer dispersion comprising a polymer, wherein the polymer comprises, based on the weight of the polymer,
 (a) from 0.55% to 5% by weight of structural units of a polymerizable surfactant having the structure of formula (I),   
       
         
           
           
               
               
           
         
         wherein R 1  is a phenyl group or a phenyl substituted alkyl group; m1 is 1, 2, 3 or 4; R 2  is an alkyl or a substituted alkyl; m2 is 0 or 1; R 3  is hydrogen or a C 1 -C 20  alkyl group; R 4  is hydrogen or a C 1 -C 20  alkyl group; A represents an alkylene group or a substituted alkylene group, having 2 to 4 carbon atoms; n is an integer in the range of from 1 to 100; and X represents hydrogen or an anionic hydrophilic group selected from —(CH 2 ) a —SO 3 M, —(CH 2 ) b —COOM, —PO 3 M 2 , —P(Z)O 2 M, or —CO—CH 2 —CH(SO 3 M)—COOM, wherein a and b are each independently an integer of from 0 to 4, Z represents a residual obtained by removing X from the general formula (I), and each M represents hydrogen, an alkali metal atom, an alkaline earth metal atom, an ammonium residue, or an alkanolamine residue; 
         (b) from 0.15% to 2% by weight of structural units of an ethylenically unsaturated monomer carrying at least one alkoxysilane functionality; and 
         (c) from 5% to 40% by weight of structural units of a styrene monomer. 
       
     
     
         2 . The aqueous polymer dispersion of  claim 1 , wherein the polymerizable surfactant has the structure of formula (I), wherein R 1  is 
       
         
           
           
               
               
           
         
       
       and m 1  is 1, 2, or 3. 
     
     
         3 . The aqueous polymer dispersion of  claim 1 , wherein A represents an ethylene group and n is an integer in the range of from 5 to 20. 
     
     
         4 . The aqueous polymer dispersion of  claim 1 , wherein the polymer comprises, based on the weight of the polymer, from 0.6% to 3% by weight of structural units of the polymerizable surfactant. 
     
     
         5 . The aqueous polymer dispersion of  claim 1 , wherein the polymer comprises, based on the weight of the polymer, from 0.2% to 0.5% by weight of structural units of the ethylenically unsaturated monomer carrying at least one alkoxysilane functionality. 
     
     
         6 . The aqueous polymer dispersion of  claim 1 , wherein the ethylenically unsaturated monomer carrying at least one alkoxysilane functionality is selected from the group consisting of (meth)acryloxyethyltrimethoxysilane, (meth)acryloxypropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane. 
     
     
         7 . The aqueous polymer dispersion of  claim 1 , wherein the polymer has a glass transition temperature of from 0 to 50° C. 
     
     
         8 . The aqueous polymer dispersion of  claim 1 , wherein the polymer comprises, based on the weight of the polymer, from 15% to 30% by weight of structural units of the styrene monomer.) 
     
     
         9 . The aqueous polymer dispersion of  claim 1 , wherein the styrene monomer is styrene. 
     
     
         10 . An aqueous coating composition comprising aqueous polymer dispersion of  claim 1 . 
     
     
         11 . The aqueous coating composition of  claim 10 , further comprising one or more pigments and/or extenders with a pigment volume concentration of from 15% to 65%.