Formaldehyde-free protein-containing binders for spunbond products
One-part binder compositions are described that may include a protein and a crosslinking combination. The crosslinking combination may include at least a first crosslinking compound and a second crosslinking compound. The first and second crosslinking compounds are individually crosslinkable with each other and with the protein. Examples of the protein include soy protein. Fiber products and methods of making the fiber products are also described. The fiber products may include organic fibers, inorganic fibers, or both, in a cured thermoset binder based on solutions of the one-part binder compositions.
1. A one-part binder composition comprising an aqueous mixture of:
a protein; and
an aqueous solution comprising a first crosslinking compound and a second crosslinking compound, wherein:
the first and second crosslinking compounds are individually crosslinkable with each other and with the protein,
the first crosslinking compound comprises a solution polymer compound of styrene and maleic anhydride,
the second crosslinking compound comprises a crosslinking agent that comprises a polysaccharide with a dextrose equivalent of 20 or less, and
the aqueous solution does not include an emulsion of the first crosslinking compound or the second crosslinking compound.
2. The one-part binder composition of claim 1 , wherein the polysaccharide is selected from the group consisting of maltodextrin, dextrin, corn syrup, starch, non-reducing sugars, and mixtures thereof.
3. The one-part binder composition of claim 1 , wherein the protein is soy protein.
4. A one-part binder composition comprising an aqueous mixture of:
a protein, and
an aqueous solution comprising a first crosslinking compound and a second crosslinking compound, wherein:
the first and second crosslinking compounds are individually crosslinkable with each other and with the protein, and
the first crosslinking compound comprises a polyvinyl alcohol,
the second crosslinking compound comprises a crosslinking agent that comprises citric acid, and
the aqueous solution does not include an emulsion of the first crosslinking compound or the second crosslinking compound.
5. The one-part binder composition of claim 4 , wherein the first crosslinking compound comprises a solution polymer.
6. The one-part binder composition of claim 4 , wherein the protein comprises a soy protein.
7. A spunbond product comprising:
a cured thermoset binder made from a binder composition comprising an aqueous mixture of:
a protein; and
an aqueous solution comprising a first crosslinking compound and a second crosslinking compound, wherein:
the first and second crosslinking compounds are individually crosslinkable with each other and with the protein,
the aqueous solution does not include an emulsion of the first crosslinking compound or the second crosslinking compound, and either:
the first crosslinking compound comprises a solution polymer compound of styrene and maleic anhydride, and the second crosslinking compound comprises a crosslinking agent that comprises a polysaccharide, or
the first crosslinking compound comprises a polyvinyl alcohol and the second crosslinking compound comprises a crosslinking agent that comprises citric acid.
8. The one-part binder composition of claim 4 , wherein the binder composition comprises a pH adjustment agent.
9. The one-part binder composition of claim 4 , wherein the binder composition has a pH of 8 or more.
10. The one-part binder composition of claim 4 , wherein the binder composition has a pH of 10 or more.
11. The one-part binder composition of claim 4 , wherein the binder composition further comprises an extender.
12. The one-part binder composition of claim 11 , wherein the extender is selected from the group consisting of starch, lignin, and rosin.
13. The one-part binder composition of claim 4 , wherein a weight ratio of (i) the protein and (ii) the first crosslinking compound and the second crosslinking compound is at least 1 to 1 by weight.
14. The one-part binder composition of claim 4 , wherein the binder composition has a viscosity of 10 cps to 1000 cps at room temperature.
15. The spunbond product of claim 7 , wherein the spunbond product has a tear strength 20% to 50% higher than a spunbond product made with standard latex.
16. The spunbond product of claim 7 , wherein the spunbond product has a cross-machine tear strength 20% to 30% greater than a spunbond product made with standard latex.
17. The spunbond product of claim 7 , wherein the spunbond product has a white or off-white color.
18. The spunbond product of claim 7 , wherein the cured thermoset binder represents 0.5 wt. % to 50 wt. % of the spunbond product.
19. The spunbond product of claim 7 , wherein the spunbond product comprises spunbond filaments made from a blend of two or more thermoplastic polymers.
20. The spunbond product of claim 19 , wherein the blend of two or more thermoplastic polymers comprises a polyester and a polyethylene.