Coating Composition with Rheology Modifier
A coating composition including a rheology modifier is described. The rheology modifier is a water-soluble polyurethane made by the condensation of a poly(alkylene glycol), a polyisocyanate and a compound including a polyalkoxylated chain and a hydrophobic end group. The composition demonstrates Leneta sag resistance of greater than about 14 and a Leneta flow and leveling of at least about 9, and a Stormer viscosity of less than about 120 Krebs units.
1 . A coating composition, comprising:
a water-soluble polyurethane rheology modifier formed by condensation of
(a) at least one compound of formula (I):
R—(OE) m —OH (I)
wherein:
R is one or more aromatic moieties having between 2 and 5 phenyl rings;
OE is a polyethoxylated chain; and
m is an number between about 6 and about 12;
(b) at least one poly(alkylene glycol); and
(c) at least one polyisocyanate,
wherein the coating composition has a Leneta sag resistance of greater than about 14 and a Leneta flow and leveling of greater than about 9, and a Stormer viscosity of less than about 120 Krebs units.
2 . The coating composition of claim 1 , wherein R is one or more aromatic moieties including a tristyryl phenyl group.
3 . The coating composition of claim 1 , wherein the one or more aromatic moieties include between about 25 and 40 carbon atoms.
4 . The coating composition of claim 1 , wherein at least one aromatic moiety of the group R has the structure of a compound of formula (III):
5 . The coating composition of claim 1 , wherein m is a number between 8 and 10.
6 . The coating composition of claim 1 , wherein the composition has a Leneta sag resistance of at least 16 and a Leneta flow and leveling of at least 10.
7 . The coating composition of claim 1 , wherein the composition has Stormer viscosity of about 90 to 120 KU.
8 . A method to improve the sag and leveling of an aqueous coating composition, comprising:
providing an aqueous coating composition; and
adding the water-soluble polyurethane rheology modifier of formula (I) or (II) to the composition to provide a coating composition having a Leneta sag resistance of at least about 14 and a Leneta flow and leveling of at least 9.
9 . The method of claim 8 , wherein the coating composition is an aqueous TiO 2 -containing latex paint system.
10 . The composition of claim 1 , wherein the poly(alkylene glycol) is poly(ethylene glycol) with molecular weight (Mw) of about 2,000 g/mol to about 20,000 g/mol.
11 . A coating composition, comprising:
a water-soluble polyurethane rheology modifier formed by condensation of
(a) at least one compound of formula (II):
wherein:
[(EO) m —(PO) n —(BO) p ] is a polyalkoxylated chain including alkoxylated units chosen from among ethoxylated units EO, propoxylated units PO, and butoxylated units BO,
m, n and p are each independently either zero, or a whole number between 2 and 250, wherein the sum of m, n and p is between 2 and 250;
(b) at least one poly(alkylene glycol); and
(c) at least one polyisocyanate,
wherein the coating composition has a Leneta sag resistance of greater than about 14 and a Leneta flow and leveling of greater than about 9, and a Stormer viscosity of less than about 120 Krebs units.
12 . The coating composition of claim 11 , wherein the polyalkoxylate is selected from compounds with alkoxylated units in blocked form, alternating form, random form, and mixtures thereof.
13 . The coating composition of claim 11 , wherein the sum of m, n, and p is a number between 2 and 20.
14 . The coating composition of claim 11 , wherein the composition has a Leneta sag resistance of at least 16 and a Leneta flow and leveling of at least 9.
15 . The coating composition of claim 11 , wherein the composition has Stormer viscosity of about 90 to 120 KU.