Low-voc aqueous coating compositions with excellent freeze-thaw stability

Abstract

The present invention is an aqueous coating composition having excellent freeze-thaw stability and a low-VOC content. The aqueous coating composition of the invention includes at least one latex polymer derived from at least one monomer and at least one polymerizable alkoxylated surfactant, at least one pigment, and water. In accordance with the invention, less than 3.0% by weight of anti-freeze agents based on the total weight of the aqueous coating composition are used in the composition. The present invention also includes a method of preparing an aqueous coating composition such as a latex paint including the above components.

1 . A aqueous coating composition, comprising: 
 (a) at least one latex polymer derived from at least one monomer and at least one polymerizable alkoxylated surfactant having the structure:      R 1 —R 2      wherein R 1  is an allyl group selected from the group consisting of CH3-CH═CH— and CH2=CH—CH2-, and R2 is a radical comprising at least two carbon atoms and at least one oxyethylene or oxypropylene unit;    (b) at least one pigment;    (c) water; and    (d) less than 3.0% by weight based on the total weight of the aqueous coating composition of anti-freeze agents.    
   
   
       2 . The composition according to  claim 1 , comprising less than 1.0% by weight based on the total weight of the aqueous coating composition of anti-freeze agents.  
   
   
       3 . The composition according to  claim 1 , being substantially free of anti-freeze agents.  
   
   
       4 . The composition according to  claim 1 , wherein R 2  is —C 6 H 3 (R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —O—CH 2 —CH(CH 2 —O—C 6 H 4 —R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH(CH 3 )) n —R 4 , —(O—CH 2 —CH 2 ) m —(O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m —(O—CH 2 —CH 2 ) n —R 4 ; R 3  is an alkyl group; R 4  is hydroxy or a polar group such as sulfonate (—SO 3 M), sulfate (—SO 4 M), phosphonate (—PO 3 M) or phosphate (—PO 4 M); M is H + , Na + , NH 4   + , K +  or Li +  with the provision that R 4  cannot be (—SO 4 M) or (—PO 4 M) if R 2  is (O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m —(O—CH 2 —CH 2 ) n —R 4 ; preferably R 4  is hydroxy or (—PO 4 M), n is from about 5 to about 100; and m is from 0 to about 100.  
   
   
       5 . The composition according to  claim 4 , wherein R 3  is C 7 -C 13  alkyl.  
   
   
       6 . The composition according to  claim 4 , wherein R 3  is C 9 H 19 .  
   
   
       7 . The composition according to  claim 4 , wherein n is from about 5 to about 40.  
   
   
       8 . The composition according to  claim 1 , wherein the at least one pigment includes at least one pigment selected from the group consisting of TiO 2 , clay, CaCO 3 , aluminum oxide, silicon dioxide, magnesium oxide, talc (magnesium silicate), barytes (barium sulfate), zinc oxide, zinc sulfite, sodium oxide, potassium oxide and mixtures thereof.  
   
   
       9 . The composition according to  claim 1 , wherein the at least one pigment includes TiO 2 , calcium carbonate or clay.  
   
   
       10 . The composition according to  claim 1 , wherein the inorganic pigment includes TiO 2 .  
   
   
       11 . The composition according to  claim 1 , wherein the at least one latex polymer is selected from the group consisting of pure acrylics, styrene acrylics, vinyl acrylics and acrylated ethylene vinyl acetate copolymers.  
   
   
       12 . The composition according to  claim 1 , wherein the at least one latex polymer includes a pure acrylic.  
   
   
       13 . The composition according to  claim 12 , wherein the at least one latex polymer is derived from at least one acrylic monomer selected from the group consisting of acrylic acid, acrylic acid esters, methacrylic acid, and methacrylic acid esters.  
   
   
       14 . The composition according to  claim 13 , wherein the at least one latex polymer is further derived from one or more monomers selected from the group consisting of styrene, α-methyl styrene, vinyl chloride, acrylonitrile, methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl esters of branched tertiary monocarboxylic acids, itaconic acid, crotonic acid, maleic acid, fumaric acid, ethylene, and C4-C8 conjugated dienes.  
   
   
       15 . The composition according to  claim 1 , further comprising one or more additives selected from the group consisting of dispersants, surfactants, rheology modifiers, defoamers, thickeners, biocides, mildewcides, colorants, waxes, perfumes and co-solvents.  
   
   
       16 . A latex paint composition, comprising: 
 (a) at least one latex polymer derived from at least one monomer and at least one polymerizable alkoxylated surfactant having the structure:      R 1 —R 2      wherein R 1  is an allyl group selected from the group consisting of CH 3 —CH═CH— and CH 2 ═CH—CH 2 —; R 2  is —C 6 H 3 (R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —O—CH 2 —CH(CH 2 —O—C 6 H 4 —R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH(CH 3 )) n —R 4 , —(O—CH 2 —CH 2 ) m —(O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m —(O—CH 2 —CH 2 ) n —R 4 ; R 3  is an alkyl group; R 4  is hydroxy or a polar group such as sulfonate (—SO 3 M), sulfate (—SO 4 M), phosphonate (—PO 3 M) or phosphate (—PO 4 M); M is H + , Na + , NH 4   + , K +  or Li +  with the provision that R 4  cannot be (—SO 4 M) or (—PO 4 M) if R 2  is (O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m - 13  (O—CH 2 —CH 2 ) n —R 4 ; preferably R 4  is hydroxy or (—PO 4 M), n is from about 5 to about 100; and m is from 0 to about 100.    (b) at least one latex polymer derived from at least one acrylic monomer selected from the group consisting of acrylic acid, acrylic acid esters, methacrylic acid, and methacrylic acid esters;    (c) at least one pigment;    (d) water; and    (e) less than 3.0% by weight based on the total weight of the aqueous coating composition of anti-freeze agents.    
   
   
       17 . The paint composition according to  claim 16 , wherein R 3  is C 7 -C 13  alkyl.  
   
   
       18 . The paint composition according to  claim 16 , wherein the latex polymer is a pure acrylic latex polymer.  
   
   
       19 . The paint composition according to  claim 18 , wherein the latex polymer is a butyl acrylate/methyl methacrylate copolymer.  
   
   
       20 . A method of preparing a aqueous coating composition, comprising the step of: mixing (1) at least one latex polymer derived from at least one monomer and at least one polymerizable alkoxylated surfactant having the structure:  
       R 1 —R 2    
     wherein R 1  is an allyl group selected from the group consisting of CH 3 —CH═CH— and CH 2 ═CH—CH 2 —, and R 2  is a radical comprising at least two carbon atoms and at least one oxyethylene or oxypropylene unit; and (2) at least one pigment; wherein the aqueous coating composition includes less than 3.0% by weight based on the total weight of the aqueous coating composition of anti-freeze agents.  
   
   
       21 . The method according to  claim 20 , wherein R 2  is —C 6 H 3 (R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —O—CH 2 —CH(CH 2 —O—C 6 H 4 —R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH(CH 3 )) n —R 4 , —(O—CH 2 —CH 2 ) m —(O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m —(O—CH 2 —CH 2 ) n —R 4 ; R 3  is an alkyl group; R 4  is hydroxy or a polar group such as sulfonate (—SO 3 M), sulfate (—SO 4 M), phosphonate (—PO 3 M) or phosphate (—PO 4 M); M is H + , Na + , NH 4   + , K +  or Li +  with the provision that R 4  cannot be (—SO 4 M) or (—PO 4 M) if R 2  is (O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m —(O—CH 2 —CH 2 ) n —R 4 ; preferably R 4  is hydroxy or (—PO 4 M), n is from about 5 to about 100; and m is from 0 to about 100.  
   
   
       22 . The method according to  claim 21 , wherein R 3  is C 7 -C 13  alkyl.  
   
   
       23 . The method according to  claim 21 , wherein R 3  is C 9 H 19 .  
   
   
       24 . The method according to  claim 21 , wherein n is from about 5 to about 40.  
   
   
       25 . The method according to  claim 20 , wherein the pigment is at least one pigment selected from the group consisting of TiO 2 , clay, CaCO 3 , aluminum oxide, silicon dioxide, magnesium oxide, talc (magnesium silicate), barytes (barium sulfate), zinc oxide, zinc sulfite, sodium oxide, potassium oxide and mixtures thereof.  
   
   
       26 . The method according to  claim 20 , wherein the pigment includes TiO 2 , calcium carbonate or clay.  
   
   
       27 . The method according to  claim 20 , wherein the pigment includes TiO 2 .  
   
   
       28 . The method according to  claim 20 , wherein said mixing step comprises mixing at least one latex polymer selected from the group consisting of pure acrylics, styrene acrylics, vinyl acrylics and acrylated ethylene vinyl acetate copolymers.  
   
   
       29 . The method according to  claim 20 , wherein the at least one latex polymer includes a pure acrylic.  
   
   
       30 . The method according to  claim 20 , wherein the at least one latex polymer is derived from at least one acrylic monomer selected from the group consisting of acrylic acid, acrylic acid esters, methacrylic acid, and methacrylic acid esters.  
   
   
       31 . The method according to  claim 30 , wherein the at least one latex polymer is further derived from one or more monomers selected from the group consisting of styrene, α-methyl styrene, vinyl chloride, acrylonitrile, methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl esters of branched tertiary monocarboxylic acids, itaconic acid, crotonic acid, maleic acid, fumaric acid, ethylene, and C4-C8 conjugated dienes.  
   
   
       32 . The method according to  claim 20 , wherein said mixing step comprises further mixing at least one additive selected from the group consisting of dispersants, surfactants, rheology modifiers, defoamers, thickeners, biocides, mildewcides, colorants, waxes, perfumes and co-solvents.  
   
   
       33 . The method according to  claim 20 , further comprising the step of preparing the polymer latex binder using emulsion polymerization by feeding the at least one monomer to a reactor in the presence of at least one initiator and the at least one polymerizable surfactant and polymerizing the monomers to produce the latex binder, wherein said mixing step comprises mixing the at least one pigment with the resulting latex binder to produce the aqueous coating composition.  
   
   
       34 . The method according to  claim 33 , wherein said step of preparing the polymer latex binder comprises: 
 preparing an initiator solution comprising the initiator;    preparing a monomer pre-emulsion comprising the at least one monomer    and the at least one polymerizable surfactant;    adding the initiator solution to a reactor; and    adding the monomer pre-emulsion to the reactor.    
   
   
       35 . The method according to  claim 33 , wherein said preparing step comprises feeding monomers to a reactor comprising at least one acrylic monomer selected from the group consisting of acrylic acid, acrylic acid esters, methacrylic acid, and methacrylic acid esters.  
   
   
       36 . The method according to  claim 35 , wherein said preparing step comprises feeding monomers to a reactor further comprising one or more monomers selected from the group consisting of styrene, α-methyl styrene, vinyl chloride, acrylonitrile, methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl esters of branched tertiary monocarboxylic acids, itaconic acid, crotonic acid, maleic acid, fumaric acid, ethylene, and C4-C8 conjugated dienes.  
   
   
       37 . In a method for reducing the VOC content of an aqueous coating composition comprising a polymer latex, a pigment and water, without substantially reducing the freeze-thaw stability of the aqueous coating composition, the improvement comprising preparing the latex polymer used in the aqueous coating composition from at least one monomer and at least one polymerizable alkoxylated surfactant, the at least one polymerizable alkoxylated surfactant having the structure:  
       R 1 —R 2    
     wherein R 1  is an allyl group selected from the group consisting of CH 3 —CH═CH— and CH 2 ═CH—CH 2 —, and R 2  is a radical comprising at least two carbon atoms and at least one oxyethylene or oxypropylene unit.  
   
   
       38 . The method according to  claim 37 , wherein R 2  is —C 6 H 3 (R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —O—CH 2 —CH(CH 2 —O—C 6 H 4 —R 3 )—(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH 2 ) n —R 4 , —(O—CH 2 —CH(CH 3 )) n —R 4 , —(O—CH 2 —CH 2 ) m —(O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m —(O—CH 2 —CH 2 ) n —R 4 R 3  is an alkyl group; R 4  is hydroxy or a polar group such as sulfonate (—SO 3 M), sulfate (—SO 4 M), phosphonate (—PO 3 M) or phosphate (—PO 4 M); M is H + , Na + , NH 4   + , K +  or Li +  with the provision that R 4  cannot be (—SO 4 M) or (—PO 4 M) if R 2  is (O—CH 2 —CH(CH 3 )) n —R 4  or —(O—CH 2 —CH(CH 3 )) m —(O—CH 2 —CH 2 ) n —R 4 ; preferably R 4  is hydroxy or (—PO 4 M), n is from about 5 to about 100; and m is from 0 to about 100.