Low VOC aqueous compositions of phosphorus acid functional polymers and polyurethanes
The present invention provides compositions that enable excellent hardness in coating applications, the compositions containing one or more copolymer having as copolymerized units one or more acrylic monomer with a phosphorus acid-functional group, a polymeric side chain containing multi-acid functional groups, a salt thereof, or a combination thereof, one or more polyurethane dispersion made from a high molecular weight polyol, and one or more coalescent having a normal boiling point of 190° C. or higher. The compositions may be ambient curable.
1. An aqueous composition that achieves in use an early hardness development comprising:
a. one or more copolymer having from 0.1% to 20 wt. %, based on the weight of the copolymer, of a copolymerized or functionalized acrylic or vinyl monomer having one or more acid functional group chosen from a phosphorus acid-functional group, a polymeric side chain containing multi-acid functional groups, a salt thereof, and a combination thereof,
wherein the copolymer has a glass transition temperature of 20° C. or higher;
b. one or more polyurethane dispersion containing at least 40 wt.%, based on the weight of polyurethane solids, of:
i. a first polyol having a molecular weight of at least 1,000, wherein the first polyol is a polyether polyol, or
ii. a second polyol chosen from a polyester, a polycaprolactam, a polycarbonate and a combination thereof, wherein the second polyol has a molecular weight of at least 2,000, or
iii. a combination of one or more first polyol and one or more second polyol; and
c. from 2.0 wt.% to 40.0 wt.%, based on the weight of copolymer solids of one or more coalescent having a normal boiling point of 190° C. or higher, the coalescent chosen from diacid esters, phosphate esters, isobutyrate esters, fatty ethers, alkoxylates of fatty acids, addition (co)polymer coalescents, or mixtures thereof,
wherein the weight ratio of the copolymer solids to the polyurethane dispersion solids is from 25/75 to 90/10.
2. The aqueous composition according to claim 1 , wherein the copolymerized or functionalized acrylic or vinyl monomer has one or more phosphorus acid-functional group chosen from (di)hydrogen phosphate, phosphonate, phosphinate, a salt thereof, or a mixture thereof.
3. The aqueous composition according to claim 1 , wherein the copolymer further comprises, as polymerized units, one or more ionic ethylenically unsaturated monomer chosen from an ethylenically unsaturated carboxylic acid monomer.
4. The aqueous composition according to claim 1 , wherein the copolymer further comprises, as polymerized units, one or more autooxidizable group chosen from an acetoacetoxy group.
5. An aqueous composition as claimed in claim 1 , wherein the copolymer further comprises one or more functional monomer chosen from a hydroxy-functional monomer, an amino-functional monomer, an epoxy-functional monomer, a keto-functional monomer, an isocyanate-functional monomers, or a mixture thereof.
6. The aqueous composition according to claim 1 , wherein the one or more coalescent is chosen from isobutyrate esters.
7. An aqueous composition comprising as claimed in claim 1 , wherein the amount of the coalescent ranges 5.0 to 40.0 wt.% wt.%, based on the weight of copolymer solids.
8. An aqueous composition according to claim 1 , further comprising one or more external crosslinker.