Formaldehyde-free binder compositions and methods of making the binders
Formaldehyde-free binder compositions are described that include an aldehyde or ketone, an organic anhydride, an alkanol amine, and a nitrogen-containing salt of an inorganic acid. The binder compositions may be applied to fibers, such as glass fibers, to make formaldehyde-free, fiber-reinforced composites. Methods of making fiber-reinforced composites are also described, where such methods may include mixing an alkanol amine with an organic anhydride to make a first mixture, and adding a reducing sugar to the first mixture to make a second mixture. A nitrogen-containing salt may be added to the second mixture to make a binder composition, which may be applied to fibers to form a binder-fiber amalgam. The amalgam may be heated to cure the binder composition and form the fiber-reinforced composite.
1. A formaldehyde-free binder composition comprising:
an aldehyde or ketone;
a reaction product of a monomeric organic anhydride and an alkanol amine; and
a nitrogen-containing salt of an inorganic acid, wherein:
the reaction product reacts with the nitrogen-containing salt of the inorganic acid when the binder composition is cured, and
the composition has a pH of between 2 and 4.5.
2. The formaldehyde-free binder composition of claim 1 , wherein the aldehyde or ketone is a reducing sugar.
3. The formaldehyde-free binder composition of claim 2 , wherein the reducing sugar is dextrose.
4. The formaldehyde-free binder composition of claim 1 , wherein the monomeric organic anhydride is chosen from maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, perhydrophthalic anhydride, itaconic anhydride, and succinic anhydride.
5. The formaldehyde-free binder composition of claim 1 , wherein the monomeric organic anhydride is maleic anhydride.
6. The formaldehyde-free binder composition of claim 1 , wherein the alkanol amine has the structure:
wherein R 1 , R 2 , and R 3 are independently chosen from, a hydrogen, a C 1-10 alkyl group, an aromatic group, and a C 1-10 hydroxy alkyl group, and wherein at least one of R 1 , R 2 , and R 3 is a hydroxyl alkyl group.
7. The formaldehyde-free binder composition of claim 1 , wherein the alkanol amine is chosen from monoethanol amine, diethanol amine, and triethanol amine.
8. The formaldehyde-free binder composition of claim 1 , wherein the nitrogen-containing salt is an unsubstituted ammonium salt.
9. The formaldehyde-free binder composition of claim 1 , wherein the nitrogen-containing salt is a substituted ammonium salt, and the substituted ammonium salt is an ammonium salt that has a hydrogen atom replaced by an organic moiety.
10. The formaldehyde-free binder composition of claim 1 , wherein the nitrogen-containing salt is a substituted ammonium salt having a polyammonium ion, and the substituted ammonium salt is an ammonium salt that has a hydrogen atom replaced by an organic moiety.
11. The formaldehyde-free binder composition of claim 10 , wherein the polyammonium ion is chosen from ethylene diammonium ion, 1,3-propanediammonium ion, 1,4-butanediammonium ion, 1,5-pendanediammonium ion, 1,6-hexanediammonium ion, α,α′-diaminoxylene ion, diethylenetriammonium ion, triethylenetetraammonium ion, tetraethylenepentammonium ion, and diamino benzene ion.
12. The formaldehyde-free binder composition of claim 1 , wherein inorganic acid is phosphoric acid.
13. The formaldehyde-free binder composition of claim 1 , wherein the nitrogen-containing salt of an inorganic acid is chosen from ethylene diammonium phosphate and hexamethylene diammonium phosphate.
14. The formaldehyde-free binder composition of claim 1 , wherein the binder composition comprises one or more additional compounds chosen from adhesion promoters, oxygen scavengers, moisture repellants, solvents, emulsifiers, pigments, fillers, anti-migration aids, coalescent aids, wetting agents, biocides, plasticizers, organosilanes, anti-foaming agents, colorants, waxes, suspending agents, anti-oxidants, and crosslinking catalysts.
15. The formaldehyde-free binder composition of claim 1 , wherein a molar ratio of the alkanol amine to the aldehyde or ketone is about 1:6.
16. The formaldehyde-free binder composition of claim 1 , wherein the composition has a pH of between 3 and 4.2.
17. The formaldehyde-free binder composition of claim 1 , wherein the binder composition comprises an organic acid.
18. The formaldehyde-free binder composition of claim 17 , wherein the organic acid comprises citric acid.
19. The formaldehyde-free binder composition of claim 1 , wherein the aldehyde or ketone comprises a multifunctional aldehyde.
20. The formaldehyde-free binder composition of claim 19 , wherein the multifunctional aldehyde comprises glyoxal.
21. The formaldehyde-free binder composition of claim 1 , wherein the binder composition further comprises a urea compound.
22. The formaldehyde-free binder composition of claim 1 , wherein the binder composition comprises a reaction product of a urea compound and the aldehyde or ketone.
23. The formaldehyde-free binder composition of claim 22 , wherein the aldehyde or ketone comprises glyoxal.
24. The formaldehyde-free binder composition of claim 1 , wherein the aldehyde or ketone comprises fructose.
25. The formaldehyde-free binder composition of claim 1 , wherein the binder composition is an aqueous solution.
26. A binder composition comprising:
a reducing sugar;
a reaction product of maleic anhydride and an ethanol amine; and
a nitrogen-containing salt of phosphoric acid, wherein:
the reaction product reacts with the nitrogen-containing salt of phosphoric acid when the binder composition is cured, and
the binder composition has a pH of between 2 and 4.5.
27. A binder composition comprising:
an aldehyde or ketone;
a reaction product of a monomeric organic anhydride and an alkanol amine;
a nitrogen-containing salt of an inorganic acid, and
a urea compound, wherein:
the reaction product reacts with the nitrogen-containing salt of the inorganic acid when the binder composition is cured,
the urea compound forms an additional reaction product with the aldehyde or ketone; and
the binder composition has a pH of between 2 and 4.5.
28. The binder composition of claim 27 , wherein the aldehyde or ketone comprises glyoxal.