Universal primer compositions and methods

1. A method for bonding a first substrate to a second substrate, comprising the steps of:

a. applying to one or both of the substrates a primer composition that includes i, ii, iii, and iv as defined below

i. 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;

ii. 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;

iii. optionally, a solvent;

iv. an isocyanate functional 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 (M n ) greater than about 300; and

b. applying an adhesive to at least one of the substrates; and

c. assembling the two substrates.

2. The method 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 method 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 method of claim 1 , wherein the organofunctional silane of the adhesion promoter includes two or three methoxy groups, ethoxy groups, or a combination of both groups bound to each of at least one silicon atom.

5. The method of claim 4 , wherein the organofunctional silane of the adhesion promoter 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 method of claim 1 , wherein the primer composition further includes diethylmalonate.

7. The method of claim 6 , wherein the primer composition further includes a phosphoric acid, a film forming resin, or both.

8. The method of claim 7 , wherein i) the adduct 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% is 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; and v) acid is present in an amount of about 0.01 to about 0.05% by weight.

9. The method of claim 8 , wherein the primer composition includes at least one film former, a pigment, a catalyst, or a combination thereof.

10. The method of claim 1 wherein about 1 mole of the polyisocyanate is reacted with about 1 to about 3 moles amino-silane, mercapto-silane, or a combination thereof to prepare the adhesion promoter.

11. The method of claim 1 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.

12. The method of claim 1 wherein the prepolymer derived from the reaction of at least one aliphatic polyisocyanate and a polyol has a free isocyanate content.

13. An assembly comprising:

a. a first substrate and a second substrate;

b. a primer composition that is applied to one or both of the first and second substrates, the primer composition as used in claim 1 ;

c. an adhesive that is applied to at least one of the substrates for adhering the substrates.

14. The assembly of claim 13 , wherein the first and second substrates are selected from glass, enamel, cured polyurethane, glass encapsulation materials, e-coat, galvanic zinc coats, aluminum, steels, paint, plastics, hard coated organic glazing, or any combination thereof.

15. A method for bonding a first substrate to a second substrate, comprising the steps of:

a. applying to one or both of the substrates a primer composition that includes i, ii, iii, and iv as defined below

i. 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, wherein about 1 mole of the polyisocyanate is reacted with about 2.3 to about 3 moles amino-silane, mercapto-silane, or a combination thereof to prepare the adhesion promoter;

ii. 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;

iii. optionally, a solvent;

iv. an isocyanate functional prepolymer with an isocyanate content greater than about 1%, and being the reaction product of a polyol and an aromatic polyisocyanate; and

b. applying an adhesive to at least one of the substrates and

c. assembling the two substrates.

16. The method of claim 15 wherein about 1 mole of the polyisocyanate is reacted with about 2.3 moles amino-silane, mercapto-silane, or a combination thereof to prepare the adhesion promoter.

17. A method for bonding a first substrate to a second substrate, comprising the steps of:

a. applying to one or both of the substrates a primer composition that includes i, ii, iii, and iv as defined below

i. 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—wherein the adhesion promoter is present in an amount of about 2 to about 7 percent by weight;

ii. a prepolymer derived from the reaction of at least one aliphatic polyisocyanate and a polyol, which is at least partially reacted with an active hydrogen containing moiety of an organofunctional silane, wherein the prepolymer is present in an amount of about 50 to about 65 percent by weight;

iii. optionally, a solvent;

iv. an isocyanate functional prepolymer with an isocyanate content greater than about 1 percent, and being the reaction product of a polyol and an aromatic polyisocyanate, wherein the isocyanate functional prepolymer is present in an amount of about 30 to about 40 percent by weight;

v. a stabilizer present in an amount of about 0.1 to about 0.5 percent by weight; and

vi. an acid present in an amount of about 0.01 to about 0.05 percent by weight; based on the weight of the composition;

b. applying an adhesive to at least one of the substrates and

c. assembling the two substrates.

18. The method of claim 17 wherein the adhesion promoter is present in an amount of about 4 to about 6 percent by weight;

the prepolymer derived from the reaction of at least one aliphatic polyisocyanate and a polyol is present in an amount of about 55 to about 60 percent by weight;

the isocyanate functional prepolymer with an isocyanate content greater than about 1 percent is present in an amount of about 33 to about 38 percent by weight;

the stabilizer is present in an amount of about 0.1 to about 0.5 percent by weight; and

the acid is present in an amount of about 0.01 to about 0.05 percent by weight;

based on the weight of the composition.