Reagents for heat activated polymer crosslinking
View Patent ↗The present invention is directed to nitrile-oxide precursor compounds, and their preparation and use as an irreversible cross-linking agent in polymers having appropriate functionality, i.e., alkenes, alkynes nitriles, and isocyanates. The present invention is also directed to the use of nitrile oxide compound in filled or unfilled applications such as pressure sensitive adhesives, reactive hot melts, polyurethane dispersions, thermosetting adhesives, thermoplastic adhesives or coatings.
1. A compound having the formula
where
R is an unsubstituted or a substituted C 1-17 alkyl, alkoxy, cycloalkyl, or aromatic group, with the proviso that such group cannot be derived from p-phenylene diisocyanate;
n is 2-10; and
R 1 is a branched or unbranched C 1-5 alkyl group.
2. The compound of claim 1 where R is substituted with alkyl, sulfate, sulfonate, alkoxy, CN, NO 2 or an aromatic group.
3. The compound of claim 1 where R is a biphenyl group, fused rings or repeating aromatic groups.
4. The compound of claim 1 where R is C 3-17 alkyl.
5. A process for crosslinking a polymer composition comprising adding the compound of claim 1 to a solution of a polymer comprises one or more pendant or terminal functional groups selected from the group consisting of alkenes, alkynes, nitriles and isocyanates and heating the mixture to form a nitrile oxide in situ and a crosslinked polymer.
6. A urethane composition which is stable to temperatures below 120° C. comprising the compound of claim 1 .
7. A pressure sensitive adhesive, reactive hot melt adhesive, polyurethane dispersion, thermosetting adhesive, thermoplastic adhesive or coating comprising the compound of claim 1 .
8. A polyurethane reactive hot melt adhesive comprising a compound of claim 1 .
9. A compound selected from the group consisting of:
10. A process for the generation of a nitrile oxide precursor compound comprising the steps of
a) generating a potassium enolate of ethyl nitroacetate in situ;
b) isolating said enolate; and
C) adding to said isolated enolate an isocyanate, diisocyanate or polyisocyanate material in a polar aprotic solvent.
11. The process of claim 10 wherein the polar aprotic solvent is selected from the group consisting of diglyme, monoglyme, glyme, tetrahydrofuran, dimethylformamide and dimethylsulfoxide.