Formaldehyde-free protein-containing binder compositions
One-part thermosetting binder compositions are described that may include soy protein, a first crosslinking compound, and a second crosslinking compound different from the first crosslinking compound. Upon curing, the first and second crosslinking compounds covalently bond to each other and to the soy protein to form a thermoset binder. Also describe are fiber-containing products that include a plurality of fibers and a formaldehyde-free binder. The formaldehyde-free binder is formed from a one-part, thermosetting binder composition that includes soy protein, a first crosslinking compound, and a second crosslinking compound different from the first crosslinking compound. Upon curing, the first and second crosslinking compounds covalently bond to each other and to the soy protein to form a thermoset binder.
1. A method of making a fiber product, the method comprising:
providing fibers comprising organic fibers or inorganic fibers;
applying a one-part thermoset binder composition to the fibers to form a binder-fiber amalgam, wherein the one-part thermoset binder composition is an aqueous mixture comprising:
a protein; and
an aqueous crosslinking solution comprising:
a first crosslinking compound comprising at least one carboxylic acid group; and
a second crosslinking compound comprising at least one of a hydroxyl group or an amine group,
wherein the aqueous crosslinking solution is not an emulsion;
curing the binder-fiber amalgam to form the fiber product,
wherein the curing converts the thermoset binder composition into a thermoset binder that has the first and second crosslinking compounds covalently bonded to each other and to the protein.
2. The method of claim 1 , wherein the fibers comprise both the organic fibers and the inorganic fibers.
3. The method of claim 1 , wherein the organic fibers are selected from the group consisting of carbon fibers, wood fibers, and organic polymer fibers.
4. The method of claim 1 , wherein the inorganic fibers comprise glass fibers.
5. The method of claim 1 , wherein the fibers are arranged as an insulation batt, a woven mat, a non-woven mat, or spunbond.
6. The method of claim 1 , wherein the protein comprises a vegetable protein.
7. The method of claim 6 , wherein the vegetable protein comprises soy protein.
8. The method of claim 1 , wherein the first crosslinking compound comprises an ethylenically unsaturated carboxylic anhydride.
9. The method of claim 8 , wherein the ethylenically unsaturated carboxylic anhydride comprises a reaction product of styrene and maleic anhydride.
10. The method of claim 1 , wherein the second crosslinking compound is selected from the group consisting of a polyol and an alkanol amine.
11. The method of claim 10 , wherein the polyol is selected from the group consisting of glycerol, ethylene glycol, propylene glycol, diethylene glycol, and triethylene glycol.
12. The method of claim 10 , wherein the alkanol amine is selected from the group consisting of ethanolamine, diethanolamine, and triethanolamine.
13. The method of claim 1 , wherein the one-part binder composition has a shelf life of at least one month.
14. The method of claim 1 , wherein the one-part binder composition has a viscosity of about 1 cps to about 1000 cps at a temperature of 20° C.
15. The method of claim 1 , wherein the one-part binder composition is applied to the fibers by curtain coating or spray coating the one-part binder composition on the fibers.
16. The method of claim 1 , wherein the method further comprises recycling an unused portion of the one-part binder composition.
17. The method of claim 16 , wherein the recycled one-part binder composition is applied to the fibers.
18. The method of claim 1 , wherein the fiber product is a wood-containing product.
19. The method of claim 1 , wherein the fiber product is a fiberglass insulation product.
20. The method of claim 1 , wherein the fiber product is chosen from a printed circuit board, a battery separator, a filter stock, and a reinforcement scrim.