Hase-thickened composition
View Patent ↗The present invention relates to a water-containing coating composition thickened with a hydrophobically modified alkali soluble emulsion, wherein the composition is neutralized by a combination of an alkali metal hydroxide or ammonium hydroxide and a low VOC alkanolamine.
1. A water-containing coating composition comprising a) a binder; b) a neutralized hydrophobically modified alkali soluble emulsion having pendant COO − groups; c) alkali metal cations; and d) an alkanolamine or a salt thereof; wherein the alkanolamine is characterized by having: 1 to 2 nitrogen atoms; 2 to 4 hydroxyl groups; an equivalent molecular weight per nitrogen atom in the range of 90 to 180 Daltons; a boiling point of greater 250 ° C. at 760 Torr pressure; and a pK a in the range of 8.8 to 9.9; wherein the molar concentration of alkanolamine or salt thereof is 10 to 70 mole percent based on the molar concentration of COO − groups in the composition; the mole ratio of alkanolamine to alkali metal cations is in the range 0.10 to 0.70; and the pH of the coating formulation is in the range of 7 to 10.
2. The composition of claim 1 which further includes a pigment.
3. The composition of claim 2 wherein the alkanolamine is 2-amino-2-ethylpropane-1,3-diol; butyldiethanolamine; 2-(dimethylamino)-2-(hydroxymethyl)propane-1,3-diol;2,2′-((2-hydroxypropane-1,3-diyl)bis(azanediyl))bis(2-methylpropan-1-ol);2-((2-amino-2-methylpropyl)amino)-2-(hydroxymethyl)propane-1,3-diol; or 2-(((1-aminocyclohexyl)methyl)amino)-2-(hydroxymethyl)propane-1,3-diol; or a combination thereof.
4. The composition of claim 3 wherein the concentration of alkanolamine is from 15 to 50 mole percent based on the molar concentration of COO − groups in the composition; and the molar concentration of alkali metal cations is from 50 to 90 mole percent based on the molar concentration of COO − groups in the composition.
5. The composition of claim 4 wherein the alkanolamine is 2-(dimethylamino)-2-(hydroxymethyl)propane-1,3-diol.
6. The composition of claim 4 wherein the alkanolamine is butyldiethanolamine.
7. The composition of claim 4 wherein the alkanolamine is 2-amino-2-ethylpropane -1,3-diol.
8. The composition of claim 1 wherein the pH is in the range of 7.5 to 9.5.
9. The composition of claim 1 wherein the molecular weight of the alkanolamine is 90 to 160 Daltons.
10. The composition of claim 1 which further comprises polymer-encapsulated or partially encapsulated opacifying pigment particles.