Aqueous binder compositions
An aqueous binder composition is disclosed that comprises at least one long-chain polyol having at least two hydroxyl groups and a number average molecular weight of at least 2,000 Daltons; a primary cross-linking agent comprising at least two carboxylic acid groups; and a secondary cross-linking agent comprising a short-chain polyol having at least two hydroxyl groups and a number average molecular weight less than 2,000 Daltons.
1. An aqueous binder composition comprising:
at least one long-chain polyol having at least two hydroxyl groups and a number average molecular weight of at least 2,000 Daltons;
at least 63 wt. % of a cross-linking agent comprising at least two carboxylic acid groups, based on the total solids content of the aqueous binder composition; and
a short-chain polyol having at least two hydroxyl groups and a number average molecular weight less than 2,000 Daltons; and
a catalyst,
wherein said binder composition has a pH after cure between 5 and 9 and achieves a b* color value, using L*a*b* coordinates, of less than 45.
2. The aqueous binder composition of claim 1 , wherein said cross-linking agent is a polymeric polycarboxylic acid.
3. The aqueous binder composition of claim 1 , wherein said cross-linking agent is present in the binder composition in an amount from 65 wt. % to 85 wt. %, based on the total solids content of the aqueous binder composition.
4. The aqueous binder composition of claim 1 , wherein said cross-linking agent is present in the binder composition in an amount from 70 wt. % to 80 wt. %, based on the total solids content of the aqueous binder composition.
5. The aqueous binder composition of claim 1 , wherein said long-chain polyol is selected from the group consisting of polyvinyl alcohol and polyvinyl acetate.
6. The aqueous binder composition of claim 1 , wherein said long-chain polyol is present in the binder composition in an amount from 5 wt. % to 30 wt. %, based on the total solids content of the aqueous binder composition.
7. The aqueous binder composition of claim 1 , wherein said short-chain polyol comprises one or more of a sugar alcohol, 2,2-bis(methylol)propionic acid, tri(methylol)propane, and a short-chain alkanolamine.
8. The aqueous binder composition of claim 7 , wherein said short-chain polyol comprises a sugar alcohol selected from the group consisting of glycerol, erythritol, arabitol, xylitol, sorbitol, maltitol, mannitol, iditol, isomaltitol, lactitol, cellobitol, palatinitol, maltotritol, syrups thereof, and mixtures thereof.
9. The aqueous binder composition of claim 1 , wherein said short-chain polyol is present in the binder composition in an amount from 3 wt. % to 30 wt. %, based on the total solids content of the aqueous binder composition.
10. An insulation product comprising:
a plurality of randomly oriented fibers; and
an aqueous binder composition at least partially coating said fibers, said binder composition comprising:
at least one long-chain polyol having at least two hydroxyl groups and a number average molecular weight of at least 2,000 Daltons;
at least 63 wt. % of a cross-linking agent comprising at least two carboxylic acid groups, based on the total solids content of the aqueous binder composition; and
a short-chain polyol having at least two hydroxyl groups and a number average molecular weight less than 2,000 Daltons; and
a catalyst,
wherein said binder composition has a pH after cure between 5 and 9 and achieves a b* color value, using L*a*b* coordinates, of less than 45.
11. The insulation product of claim 10 , wherein the fibers comprise one or more of mineral fibers, natural fibers, and synthetic fibers.
12. The insulation product of claim 10 , wherein the fibers comprise glass fibers, mineral wool fibers, or a mixture thereof.
13. The insulation product of claim 10 , wherein when said insulation product after cure has a thickness of 1 inch and a density of 6 lbs/ft 3 , said insulation product has a flexural elastic modulus of at least 40 psi.
14. The insulation product of claim 10 , wherein when said insulation product after cure has a thickness of 1 inch and a density of 6 lbs/ft 3 , said insulation product has a compressive strength at 10% deformation of at least 200 lbs/ft 2 .
15. The insulation product of claim 10 , wherein a ratio of molar equivalents of carboxylic acid groups to hydroxyl groups in the binder composition is from 1/0.05 to 1.0/5.0.
16. A method for controlling color in insulation products formed using a formaldehyde-free binder composition, the method comprising:
preparing a formaldehyde-free binder composition comprising:
at least one long-chain polyol having at least two hydroxyl groups and a number average molecular weight of at least 2,000 Daltons;
at least 63 wt. % of a cross-linking agent comprising at least two carboxylic acid groups, based on the total solids content of the aqueous binder composition; and
a short-chain polyol having at least two hydroxyl groups and a number average molecular weight less than 2,000 Daltons; and
a catalyst, and
curing said binder composition to achieve a b* color value, using L*a*b* coordinates, of less than 45 and a cured binder pH of between 5 and 9.
17. The method of claim 16 , wherein said cross-linking agent is a polymeric polycarboxylic acid.
18. The method of claim 16 , wherein a ratio of molar equivalents of carboxylic acid groups to hydroxyl groups is from 1/0.05 to 1.0/5.0.
19. The method of claim 16 , wherein said long-chain polyol is selected from the group consisting of polyvinyl alcohol and polyvinyl acetate.
20. The method of claim 16 , wherein said long-chain polyol is present in the binder composition in an amount from 5 wt. % to 30 wt. %, based on the total solids content of the aqueous binder composition.
21. The method of claim 16 , wherein said short-chain polyol comprises one or more of a sugar alcohol, 2,2-bis(methylol)propionic acid, tri(methylol)propane, and a short-chain alkanolamine.
22. The method of claim 16 , wherein said short-chain polyol is present in the binder composition in an amount from 3 wt. % to 30 wt. %, based on the total solids content of the aqueous binder composition.
23. The method of claim 16 , wherein said binder composition includes a ratio of long-chain polyol to short-chain polyol is from 0.1/0.9 to 0.9/0.1.
24. The method of claim 16 , wherein prior to curing, the pH of the binder composition is adjusted by 0.25 to 1.5 pH units.
25. The method of claim 24 , wherein said pH is adjusted by the addition of one or more of a non-volatile base and alkaline water.
26. The method of claim 16 , wherein said binder composition achieves a b* color value, using L*a*b* coordinates, of less than 40.
27. The method of claim 16 , wherein said binder composition has an un-cured pH of 2 to 5.
28. The method of claim 16 , wherein said binder composition has a cured pH of between 6.0 and 8.0.
29. The method of claim 16 , wherein when said insulation product after cure has a thickness of 1 inch and a density of 6 lbs/ft 3 , said insulation product has a flexural elastic modulus of at least 40 psi.
30. The method of claim 16 , wherein when said insulation product after cure has a thickness of 1 inch and a density of 6 lbs/ft 3 , said insulation product has a compressive strength at 10% deformation of at least 200 lbs/ft 2 .
31. The method of claim 16 , wherein when said insulation product after cure has a thickness of 1 inch and a density of 6 lbs/ft 3 , said insulation product has a bond strength at break of at least 7.5 lbs/ft 2 /LOI.