Gypsum board and gypsum slurry formed using a phosphorus containing compound
In general, the present invention is directed to the use of particular phosphorus containing compounds for making a gypsum board. The phosphorus containing compound may be a phosphite or a phosphate having a certain formula. In this regard, the present invention is directed to a slurry for making a gypsum board wherein the slurry includes such phosphorus containing compound. The present invention is also directed to a method of making a gypsum board from the slurry as well as a resulting gypsum board.
1. A slurry for making a gypsum board, the slurry comprising
stucco,
water, and
a phosphorus containing compound comprising a phosphite, a phosphate having the formula P(O) n (X) m wherein n is from 0 to 4, m is from 1 to 6, the sum of n and m is from 3 to 6, and X is halogen, sulfur, or selenium, a salt thereof, or a mixture thereof.
2. The slurry of claim 1 , wherein the phosphorus containing compound comprises a phosphite.
3. The slurry of claim 1 , wherein the phosphorus containing compound comprises a phosphate having the formula P(O) n (X) m wherein n is from 0 to 4, m is from 1 to 6, the sum of n and m is from 3 to 6, and X is halogen, sulfur, or selenium, a salt thereof.
4. The slurry of claim 3 , wherein X includes fluoro.
5. The slurry of claim 3 , wherein n is from 2 to 3.
6. The slurry of claim 3 , wherein m is from 1 to 2.
7. The slurry of claim 1 , wherein the phosphorus containing compound comprises a halophosphate.
8. The slurry of claim 1 , wherein the phosphorus containing compound comprises a monohalophosphate.
9. The slurry of claim 1 , wherein the phosphorus containing compound comprises a salt including an alkali metal, an alkaline earth metal, a transition metal, or a combination thereof.
10. The slurry of claim 1 , wherein the phosphorus containing compound comprises sodium monofluorophosphate.
11. The slurry of claim 1 , wherein the phosphorus containing compound is present in the slurry in an amount of from 0.01 wt. % to 5 wt. % based on the weight of the stucco.
12. The slurry of claim 1 , wherein the weight ratio of the water to the stucco is from 0.1 to 3.
13. The slurry of claim 1 , wherein the slurry further comprises a dispersant.
14. The slurry of claim 13 , wherein the dispersant comprises a sulfonate, a polycarboxylate ether, a polycarboxylate ester, or a mixture thereof.
15. The slurry of claim 1 , wherein the gypsum slurry is characterized by having a set time of 3.5 minutes or less using a ¼ pound Gillmore needle according to ASTM C266.
16. A method for making a gypsum board, the method comprising
depositing the slurry of claim 1 on a first facing material,
providing a second facing material on the slurry, and
allowing the stucco to convert to calcium sulfate dihydrate.
17. A gypsum board made according to the method of claim 16 .