Viscosity modified formaldehyde-free binder compositions
Viscosity-modified carbohydrate binder compositions are described. The binder compositions may include a carbohydrate, a nitrogen-containing compound, and a thickening agent. The binder compositions may have a Brookfield viscosity of 7 to 50 centipoise at 20° C. The thickening agents may include modified celluloses such as hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC), and polysaccharides such as xanthan gum, guar gum, and starches.
1. A carbohydrate binder composition comprising a reducing sugar, a nitrogen-containing compound, and a thickening agent, wherein:
the nitrogen-containing compound is a reaction product of urea (H 2 N—CO—NH 2 ) and glyoxal,
the binder composition has a Brookfield viscosity of 7 to 50 centipoise at 20° C. as measured with a Brookfield viscometer using spindle 18 at 60 rpm,
the binder composition is formaldehyde-free and forms a polymerization product, and
the thickening agent has a concentration of 0.03 wt. % to 0.3 wt. % of the binder composition.
2. The carbohydrate binder composition of claim 1 , wherein the reducing sugar is chosen from dextrose, fructose, allose, galactose, xylose, ribose, maltose, cellobiose, and lactose.
3. The carbohydrate binder composition of claim 1 , wherein the reaction product comprises 4,5-dihydroxyimidazolidin-2-one.
4. The carbohydrate binder composition of claim 1 , wherein the binder composition further comprises a reaction product of an organic anhydride and an alkanol amine.
5. The carbohydrate binder composition of claim 1 , wherein the thickening agent comprises a modified cellulose.
6. The carbohydrate binder composition of claim 5 , wherein the modified cellulose is chosen from carboxymethyl cellulose (CMC), and hydroxyethyl cellulose (HEC).
7. The carbohydrate binder composition of claim 1 , wherein the thickening agent comprises a polysaccharide.
8. The carbohydrate binder composition of claim 7 , wherein the polysaccharide is chosen from xanthan gum, guar gum, and starch.
9. The carbohydrate binder composition of claim 1 , wherein the thickening agent comprises acrylic acid.
10. The carbohydrate binder composition of claim 1 , wherein:
the reducing sugar comprises dextrose;
the nitrogen-containing compound is 4,5-dihydroxyimidazolidin-2-one; and
the thickening agent comprises hydroxyethyl cellulose, wherein the hydroxyethyl cellulose has a concentration of 0.05 wt. % to 0.3 wt. % of the binder composition.
11. The carbohydrate binder composition of claim 1 , wherein:
the reducing sugar comprises dextrose;
the nitrogen-containing compound is 4,5-dihydroxyimidazolidin-2-one; and
the thickening agent comprises xanthan gum, wherein the xanthan gum has a concentration of 0.03 wt. % to 0.2 wt. % of the binder composition.
12. A blended carbohydrate binder composition comprising a reducing sugar, a nitrogen-containing compound, and a second binder composition, wherein:
the nitrogen-containing compound is a reaction product of urea (H 2 N—CO—NH 2 ) and glyoxal,
the blended carbohydrate binder composition has a Brookfield viscosity of 7 to 50 centipoise at 20° C. as measured with a Brookfield viscometer using spindle 18 at 60 rpm,
the second binder composition is formaldehyde-free and forms a polymerization product, and
the blended carbohydrate binder composition comprises a thickening agent at a concentration from 0.03 wt. % to 0.3 wt. % of the blended carbohydrate binder composition.
13. The blended carbohydrate binder composition of claim 12 , wherein the second binder composition is selected from the group consisting of a latex binder composition and a solution polymer binder composition.
14. The carbohydrate binder composition of claim 1 , wherein the binder composition is an aqueous solution.
15. The blended carbohydrate binder composition of claim 12 , wherein the second binder composition is a solution polymer binder composition.
16. The carbohydrate binder composition of claim 1 , wherein the molar ratio of the nitrogen-containing compound to the reducing sugar is in a range from 1:4 to 1:10.