Universal primer compositions and methods
View Patent ↗A composition for and method for bonding a substrate. In general, applied to a substrate will be a primer composition that includes an adhesion promoter, which is an adduct prepared by the reaction of at least one aromatic polyisocyanate compound, with an active hydrogen containing moiety of an organofunctional silane, and a prepolymer derived from the reaction of at least one aliphatic polyisocyanate and a polyol, and is at least partially reacted with an active hydrogen containing moiety of an organofunctional silane.
1. A primer composition that includes a, b, c, and d as defined below;
a. an adhesion promoter, which is an adduct prepared by the reaction of at least one aromatic polyisocyanate compound, with an active hydrogen containing moiety of an organofunctional silane;
b. a prepolymer derived from the reaction of at least one aliphatic polyisocyanate and a polyol, and is at least partially reacted with an active hydrogen containing moiety of an organofunctional silane;
c. a solvent; and
d. an isocyanate function prepolymer with an isocyanate content greater than about 1%, and being the reaction product of a polyol and an aromatic polyisocyanate wherein the polyol has a functionality of greater than about 2 and a molecular weight (Mn) greater than about 300;
wherein the adhesion promoter is present in a weight ratio of about 1:100 to about 2:1 parts adhesion promoter to aliphatic isocyanate prepolymer.
2. The composition of claim 1 , wherein the at least one aromatic polyisocyanate compound includes a thiophosphate, a phosphate, a thiophosphane moiety or any combination thereof.
3. The composition of claim 1 , wherein i) the at least one aromatic polyisocyanate compound is trifunctional, ii) the at least one aromatic polyisocyanate compound includes tris(isocyanatophenyl)thiophosphate, or both i) and ii).
4. The composition of claim 1 , wherein the organofunctional silane includes two or three methoxy groups, ethoxy groups, or both bound to each of at least one silicon atom.
5. The composition of claim 4 , wherein the organofunctional silane is a mercapto silane, an amino silane, or a combination thereof, and wherein about 1 mole of the polyisocyanate is reacted with about 1 to about 3 moles amino-silane, mercapto-silane, or a combination thereof, provided that the molar ratio of hydrogen active groups to isocyanate groups is less than 1.0.
6. The composition of claim 1 , which further includes diethylmalonate.
7. The composition of claim 6 , which further includes a phosphoric acid, a film forming resin, or both.
8. The composition of claim 7 , wherein i) the adhesion promoter is present in an amount of about 0.5 to about 20% by weight; ii) the prepolymer derived from the reaction of at least one aliphatic polyisocyanate and a polyol is present in an amount of about 10 to about 50% by weight; iii) the aromatic polyisocyanate functional prepolymer with an isocyanate content greater than about 1 will be present in an amount of about 20 to about 70% by weight; the solvent is present in an amount of about 40 to about 80% by wt.; iv) diethylmalonate is present in an amount of about 0.1 to about 0.5% by weight; v) acid is present in an amount of about 0.01 to about 0.05 by weight; or vi) any combination of i) through v).
9. The composition of claim 8 , which further includes at least one film former, a pigment or a catalyst, or a combination thereof.
10. The composition of claim 1 used as a primer with an adhesive on a substrate exhibits 100 percent cohesive failure in an adhesion peel test after aging 7 days at room temperature; further aging for an additional 7 days subject to water immersion; after aging an additional 7 days at 90° C.; after 7 additional days cataplasma cycling; or after 14 additional days cataplasma cycling.
11. A composition according to claim 10 wherein the adhesive is a one or two part urethane composition.
12. An additive for a primer composition comprising i) an adhesion promoter that is a reaction product of an organofunctional silane and an aromatic isocyanate; and
ii) a second reaction product that is an isocyanate functional prepolymer with an isocyanate content greater than about 1% formed by the reaction of a polyol having a functionality of greater than about 2 and a molecular weight (M n ) greater than about 300 and an aromatic isocyanate;
wherein a primer composition containing the additive when used as a primer with an adhesive on a substrate exhibits 100 percent cohesive failure in an adhesion peel test after aging for 7 days at room temperature; and further aging using one or more of the following time periods and conditions; a) 7 days of water immersion; b) 7 days at 90° C.; c) 7 additional of cataplasma cycling; and d) 14 days cataplasma cycling.
13. An additive according, to claim 12 wherein a primer composition containing the additive exhibits
i) a solids content in the range of about 30 to about 50;
ii) an isocyanate content of about 1 to about 7%,
iii) a density of about 0.92 to about 0.95 g/cm 3 ,
iv) a silane content of about 1 to about 5%, or
v) any combination of i) through iv).