Rapid cure thermosets from 5- and 6- membered cyclic enamine compounds made from dialdehydes
The present invention provides thermosetting aqueous binder compositions of one or more cyclic enamine, including bis-enamines and di- or higher functional enamines, optionally containing a water soluble or dispersible or dispersible primary amine compound. The binders are at least substantially formaldehyde free, need no polycarboxylic or polycarboxylate component, and yet provide excellent hot wet tensile strength when cured for as little time as a minute or less in use.
1. A thermosetting aqueous binder composition comprising one or more cyclic enamine compound and/or oligomer thereof and ammonia or ammonium hydroxide.
2. The binder composition as claimed in claim 1 , wherein the cyclic enamine or oligomer comprises a bis-enamine or its oligomer.
3. The binder composition as claimed in claim 2 , wherein the bis-enamine or oligomer is 1,4-dihydropyridine or oligo(1,4-dihydropyridine).
4. The binder composition as claimed in claim 1 , further comprising one or more water soluble or dispersible non-volatile amine.
5. The binder composition as claimed in claim 4 , comprising the cyclic enamine compound and water soluble or dispersible non-volatile amine in a molar ratio of cyclic enamine groups to amine groups of 0.1:1 to 15:1.
6. The binder composition as claimed in claim 4 , wherein the water soluble or dispersible non-volatile amine is a primary amine chosen from aliphatic hydroxy amines having one or more primary amine groups, aromatic amines having one or more primary amine groups, amine functional polymers, proteins, gelatins, amino acids, amino-saccharides, polypeptides, urea, mixtures of the primary amine and polyols, and mixtures of the primary amine and carbohydrates.
7. The binder composition as claimed in claim 6 , wherein the water soluble or dispersible non-volatile amine is a poly(primary amine) having two or more primary amine groups.
8. The binder composition as claimed in claim 1 , optionally, further comprising one or more polyol, carbohydrate, or sugar alcohol.
9. The binder composition as claimed in claim 1 , wherein the one or more cyclic enamine compound or oligomer thereof is generated from a di-aldehyde in an excess of ammonia, ammonium hydroxide or a salt of ammonia.
10. A method of making the binder composition as claimed in claim 1 comprising adding one or more di-aldehyde or aldehyde oligomer having two or more aldehyde groups into an excess of ammonia or ammonium hydroxide in a molar ratio of ammonia groups to aldehyde groups of 1.5:1 or more.