Water-resistant additives for gypsum wood fiber products
View Patent ↗Emulsions are provided which are useful in imparting water-resistance to gypsum wood fiber products. In one embodiment, the emulsions comprise a wax or a combination of waxes, an alkyl phenol, at least one surfactant, Polynaphthalenesulfonic acid, and an alkali metal hydroxide. In another embodiment, the emulsions comprise a wax or a combination of waxes, an alkyl phenol, at least one surfactant, polynaphthalenesulfonic acid, an alkali metal hydroxide, and a complexed starch.
1. An emulsion comprising:
at least one wax;
a C 24 -C 36 polymerized methylene coupled alkyl phenol;
at least one surfactant;
polynaphthalenesulfonic acid;
an alkali metal hydroxide; and
water.
2. The emulsion of claim 1 wherein the alkali metal hydroxide is selected from the group consisting of sodium hydroxide and potassium hydroxide.
3. The emulsion of claim 1 wherein the C 24 -C 36 polymerized methylene coupled alkyl phenol is present in an amount from about 0.5 to about 10 wt. %, based on total weight of the emulsion.
4. The emulsion of claim 1 wherein the surfactant is selected from the group consisting of a sorbitan ester, a polyoxyethylene sorbitan ester, and combinations thereof.
5. The emulsion of claim 4 wherein the sorbitan ester is sorbitan monostearate.
6. The emulsion of claim 5 wherein the sorbitan monostearate is present in an amount from about 0.5 to about 5 wt. %, based on the total weight of the emulsion.
7. The emulsion of claim 4 wherein the polyoxyethylene sorbitan ester is polyoxyethylene sorbitan monostearate.
8. The emulsion of claim 7 wherein the polyoxyethylene sorbitan monostearate is present in an amount from about 0.5 to about 5 wt. %, based on the total weight of the emulsion.
9. The emulsion of claim 1 wherein the surfactant is a combination of sorbitan monostearate and polyoxyethylene sorbitan monostearate.
10. The emulsion of claim 9 wherein the combination of sorbitan monostearate and polyoxyethylene sorbitan monostearate is present in an amount from about 0.5 to about 5 wt. %, based on the total weight of the emulsion.
11. The emulsion of claim 1 wherein the emulsion comprises a first wax having a melting point of at least 120° F., and a second wax that is a saponifiable wax.
12. The emulsion of claim 11 wherein the first wax is present in an amount from about 30 to about 45 wt. % and the second wax is present in an amount from about 3 to about 5 wt. %, based on the total weight of the emulsion.
13. The emulsion of claim 1 wherein the polynaphthalenesulfonic acid is present in an amount from about 0.25 to about 5 wt. %, based on the total weight of the emulsion.
14. The emulsion of claim 1 further comprising a starch.
15. The emulsion of claim 14 wherein the starch is a complexed starch comprising a starch and a complexing agent selected from the group consisting of a borate compound and a molybdenum compound.
16. The emulsion of claim 15 wherein the starch is selected from the group consisting of unmodified starch, acid-modified starch, hydroxyethylated starch, oxidized starch, and cationic starch.
17. The emulsion of claim 16 wherein the starch is acid-modified starch.
18. The emulsion of claim 15 wherein the ratio of the complexing agent to the starch on a weight per weight basis is from about 1:4 to about 1:20.
19. An emulsion comprising:
a first wax having a melting point of at least 120° F. in an amount of about 30 wt. % to about 45 wt. % by weight, based on the total weight of the emulsion;
a saponifiable wax in an amount from about 3 to about 5 wt. %, based on the total weight of the emulsion;
a combination of surfactants in an amount from about of about 0.5 to about 5 wt. %, based on the total weight of the emulsion
a C 24 -C 36 polymerized methylene coupled alkyl phenol in an amount from about 0.5 to about 10 wt. %, based on the total weight of the emulsion;
a polynaphthalenesulfonic acid in an amount from about 0.25% to about 5 wt. %, based on the total weight of the emulsion;
water in an amount from about 45 to about 65 wt. %, based on the total weight of the emulsion; and
an alkali metal hydroxide in an amount from about 0.5% to about 3 wt. %, based on the total weight of the emulsion.
20. The emulsion of claim 19 further comprising a complexed starch, the complexed starch comprising a starch and a complexing agent selected from the group consisting of a borate compound and a molybdenum compound.
21. A method for making a gypsum wood fiber article, comprising the steps of:
(a) mixing a slurry containing from about 5 wt. % to about 50 wt. % of a wood fiber, from about 5 wt. % to about 50 wt. % of gypsum, from about 1 wt. % to about 3 wt. % of the emulsion of claim 20 , based on the total weight of the slurry and water;
(b) distributing the slurry onto a vacuum wire for formation of a mat;
(c) partially drying the mat of step (b);
(d) compressing the mat of step (c) through a series of vacuum belt rolls; and
(e) drying the compressed mat of step (d) in an oven.
22. The method of claim 21 wherein the emulsion comprises:
a first wax having a melting point of at least 120° F. in an amount of about 30 to about 45 wt. %, based on the total weight of the emulsion;
a saponifiable wax in an amount from about 3 to about 5 wt. %, based on the total weight of the emulsion;
a combination of surfactants in an amount from about 0.5 to about 5%, based on the total weight of the emulsion;
an alkyl phenol in an amount from about of about 5% to about 10% wt. %, based on the total weight of the emulsion;
a polynaphthalenesulfonic acid in an amount from about 0.25% to about 5% wt. %, based on the total weight of the emulsion;
water in an amount of from about 45 to about 65 wt. %, based on the total weight of the emulsion; and
an alkali metal hydroxide in an amount from about 0.5% to about 3 wt. %, based on the total weight of the emulsion.
23. The method of claim 22 wherein the emulsion further comprises a complexed starch, the complexed starch comprising a starch and a complexing agent selected from the group consisting of a borate compound and a molybdenum compound.