Binder compositions and associated methods
Disclosed are formaldehyde-free, thermally-curable, alkaline, aqueous binder compositions, curable to formaldehyde-free, water-insoluble thermoset polyester resins, and uses thereof as binders for non-woven fibers and fiber materials.
1. A method of making a formaldehyde-free binder comprising
drying a substantially unreacted aqueous solution comprising (a) a polycarboxylic acid component selected from the group consisting of a dicarboxylic acid, tricarboxylic acid, tetracarboxylic acid, pentacarboxylic acid, anhydride or salt derivatives thereof, and combinations thereof, (b) a polymeric polyhydroxyl component, (c) a catalyst, and (d) a base to form a dried mixture, and
curing the dried mixture to form the formaldehyde-free binder as a water-insoluble thermoset polyester resin,
wherein the aqueous solution includes sufficient base to have an alkaline pH, and
wherein the catalyst is selected from the group consisting of ammonium para-toluene sulfonate, ammonium naphthalene disulfonate, ammonium sulfate, ammonium chloride, sulfuric acid, lactic acid, lead acetate, sodium acetate, calcium acetate, zinc acetate, organotin compounds, titanium esters, antimony trioxide, germanium salts, sodium hypophosphite, sodium phosphite, methane sulfonic acid and para-toluene sulfonic acid, and mixtures thereof.
2. The method of claim 1 , wherein the aqueous solution further comprises a silicon-containing compound.
3. The method of claim 2 , wherein the silicon-containing compound is a silylether or an alkylsilyl ether.
4. The method of claim 2 , wherein the silicon-containing compound is gamma-aminopropyltriethoxy silane.
5. The method of claim 1 , wherein the polycarboxylic acid component is citric acid.
6. The method of claim 1 , wherein the catalyst is sodium hypophosphite.
7. The method of claim 1 , wherein the base is selected from the group consisting of ammonia, sodium carbonate, sodium hydroxide, and potassium hydroxide.
8. The method of claim 2 , wherein the base is selected from the group consisting of ammonia, sodium carbonate, sodium hydroxide, and potassium hydroxide.
9. The method of claim 2 , wherein the aqueous solution comprises (a) an ammonium salt of a dicarboxylic acid and (b) partially hydrolyzed polyvinyl acetate, wherein the pH of the solution is in the range from about 7 to about 10.
10. The method of claim 9 , wherein the dicarboxylic acid is maleic acid.
11. The method of claim 9 , wherein the partially hydrolyzed polyvinyl acetate is an 87-89% partially hydrolyzed polyvinyl acetate.
12. The method of claim 9 , wherein the ratio of the number of molar equivalents of carboxylic acid salt groups on the dicarboxylic acid to the number of molar equivalents of hydroxyl groups on the partially hydrolyzed polyvinyl acetate is in the range from about 0.6:1 to about 1.2:1.
13. The method of claim 9 , wherein the catalyst is sodium hypophosphite.
14. The method of claim 9 , wherein the catalyst is a sulfuric acid or a sulfonic acid, or a salt or derivative thereof.
15. The method of claim 9 , wherein the silicon-containing compound is an amino substituted silicon-containing compound.
16. The method of claim 9 , wherein the silicon-containing compound is a silylether.
17. The method of claim 9 , wherein the said silicon-containing compound is selected from gamma-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and mixtures thereof.
18. The method of claim 9 , wherein the base is selected from the group consisting of ammonia, sodium carbonate, sodium hydroxide, and potassium hydroxide.
19. The method of claim 18 , wherein the base is sodium hydroxide.