Compositions and methods for making instant-set aqueous coatings
The present invention provides two-component instant-set aqueous coating compositions that provide coating films having good film quality despite a rapid film build and set. The compositions comprise, as Component I, a film-forming aqueous anionically stabilized polymer composition, such as an elastomeric acrylic or vinyl polymer, and one or more surfactants; and, as Component II, a polycation tolerant mixture of polycation, an aqueous polymer composition, such as a film-forming acrylic emulsion polymer, and a nonionic or ethoxylated anionic surfactant having an average of 7 or more or, preferably, 9 or more ethylene oxide groups per molecule. Component I can be an elastomeric roof coating composition. The compositions can be co-sprayed to form coatings, e.g. roof coatings.
1 . A two-component instant-set aqueous coating composition comprising:
A. a Component I comprising:
a film-forming aqueous anionically stabilized polymer composition of a polymer having two or more acid functional groups; and,
one or more surfactants in a total amount of from 0.04 to 3 wt. %, based on the total weight of Component I; and,
B. a polycation tolerant Component II, separate from Component I, comprising:
an aqueous polymer composition in the amount of from 25 to 99.2 wt. %, based on the total weight of component II, wherein the aqueous polymer composition comprises an acrylic polymer or a styrene acrylic polymer; and,
from 0.8 to 20 wt. %, based on the total weight of Component II, of a polycation that sets an anionically stabilized polymer, wherein the composition of Component II is stabilized with a nonionic surfactant, a polyethoxylated anionic surfactant having an average of from 7 to 100 ethylene oxide groups per molecule, or a mixture of two or more thereof, and,
further wherein, the total amount of the surfactant in Component II ranges from 0.5 to 6.5 wt. %, based on the total weight of the aqueous polymer composition.
2 . The two-component instant-set aqueous coating composition as claimed in claim 1 , wherein in Component I, the amount of the film-forming aqueous anionically stabilized polymer composition in Component I ranges from 25 to 70 wt. %.
3 . The two-component instant-set aqueous coating composition as claimed in claim 1 , wherein the weight ratio of Component I to Component II ranges from 50:1 to 1:1.
4 . The two-component instant-set aqueous coating composition as claimed in claim 1 , wherein in Component I, the film-forming aqueous anionically stabilized polymer composition is an aqueous emulsion polymer comprising, in copolymerized form, (i) one or more acid group-containing monomers or salts thereof in the amount of from 0.4 to 3 wt. %, based on the total weight of monomers used to make the aqueous emulsion polymer; and, further wherein, the film-forming aqueous anionically stabilized polymer composition in Component I has a measured glass transition temperature (measured Tg) of from −50 to 30° C., wherein the measured Tg is determined by differential scanning calorimetry (DSC) in accordance with ASTM E-1356-08 (2014) and the given homopolymer or copolymer was dried for 24 hours and was then conditioned for at least 12 hours at 60° C. prior to the DSC, and then cooled to a temperature of −70° C. before scanning from −70° C. to 130° C. with a ramp rate of 10° C./minute, and reporting the measured Tg as the inflection point of the curve of heat flow vs. temperature or the maximum value on the plot of its derivative.
5 . The two-component instant-set aqueous coating composition as claimed in claim 1 , wherein the film-forming aqueous anionically stabilized polymer composition of Component I is an elastomeric polymer having a measured Tg of 15° C. or less and is an emulsion polymer of the (i) one or more acid group-containing monomers or salts thereof, (ii) one or more soft monomers which would if polymerized to yield a homopolymer having a weight average molecular weight of 50,000 or greater form such a homopolymer with a measured Tg (DSC) of −20 to −150° C.; and, (iii) one or more vinyl or acrylic comonomers.
6 . The two-component instant-set aqueous coating composition as claimed in claim 1 , wherein Component I further contains one or more inorganic pigments, fillers or extenders.
7 . The two-component instant-set aqueous coating composition as claimed in claim 1 , wherein the aqueous polymer composition in the polycation tolerant Component II comprises a film-forming aqueous polymer composition wherein the polymer has a measured Tg of from −50 to 60° C., wherein the measured Tg is determined by differential scanning calorimetry (DSC) in accordance with ASTM E-1356-08 (2014) and the given homopolymer or copolymer was dried for 24 hours and was then conditioned for at least 12 hours at 60° C., and then cooled to a temperature of −70° C. before scanning from −70° C. to 130° C. with a ramp rate of 10°/minute, and reporting the measured Tg as the inflection point of the curve of heat flow vs. temperature or the maximum value on the plot of its derivative.
8 . The two-component instant-set aqueous coating composition as claimed in claim 7 , wherein the aqueous polymer composition in the polycation tolerant Component II comprises an aqueous emulsion polymer of (ii) one or more soft monomers which would if polymerized to yield a homopolymer having a weight average molecular weight of 50,000 or greater form such a homopolymer with a measured Tg (DSC) of −20 to −150° C.; and (iii) one or more vinyl or acrylic comonomers.
9 . The two-component instant-set aqueous coating composition as claimed in claim 1 , wherein the polycation in the Component II comprises a polycationic polymer or a multivalent metal salt.
10 . The two-component instant-set aqueous coating composition as claimed in claim 9 , wherein the polycation in Component II is chosen from a polyfunctional polyamine, a divalent metal chloride or a trivalent metal chloride.
11 . A method of making an instant-set coating from the two-component aqueous coating composition of claim 1 comprising:
separately applying streams of each of Component I and Component II to a substrate so as to mix the streams of Components I and II with one another in the air or so as to mix the streams of Component I and Component II at the surface of the substrate as the two-component composition is applied.