Pregelatinized starch with mid-range viscosity, and product, slurry and methods related thereto
Disclosed are product (e.g., panels), slurry, and methods relating to a pregelatinized starch having a mid-range viscosity (i.e., from about 20 centipoise to about 700 centipoise), and an extruded pregelatinized starch.
1. A board comprising:
a set gypsum core disposed between two cover sheets, the core formed from a slurry comprising stucco, water, and at least one extruded pregelatinized starch, wherein the extruded pregelatinized starch is formed by modifying and extruding a wet starch having a water content less than about 25% wherein the modifying at least partially hydrolyzes the starch via acid and/or enzyme modification;
the extruded pregelatinized starch having a cold water solubility greater than about 30% when measured at 25° C. and a cold water viscosity of a 10 wt. % slurry of the starch in water when measured at 25° C. and at a shear rate of 100 s −1 for 1 min is from about 120 centipoise to about 300 centipoise;
the extruded pregelatinized starch causing the set gypsum core to have a compressive strength greater than an equivalent set gypsum core made with a starch having a cold water solubility less than about 30% instead of the extruded pregelatinized starch;
the board having a core hardness of at least about 11 lbs, as determined according to ASTM C473-10.
2. The board according to claim 1 , wherein the extruded pregelatinized starch has a cold water solubility from about 30% to about 75%.
3. The board according to claim 1 , wherein the extruded pregelatinized starch has a cold water solubility from about 50% to about 75%.
4. The board according to claim 1 , wherein the extruded pregelatinized starch has a particle size from about 100 microns to about 400 microns.
5. The board according to claim 1 , wherein the extruded pregelatinized starch is in an amount from about 0.1% to about 5% by weight based on the weight of stucco.
6. The board according to claim 1 , wherein the extruded pregelatinized starch is in an amount from about 0.1% to about 3% by weight based on the weight of stucco.
7. The board according to claim 1 , wherein the slurry further comprises sodium trimetaphosphate.
8. The board according to claim 1 , wherein the board has a density from about 24 pcf to about 35 pcf.
9. The board according to claim 4 , wherein the extruded pregelatinized starch is in an amount from about 0.1% to about 5% by weight based on the weight of stucco.
10. The board according to claim 9 , wherein, the slurry further comprises sodium trimetaphosphate.
11. The board according to claim 6 , wherein the extruded pregelatinized starch has a particle size from about 100 microns to about 400 microns.
12. A method of making a board comprising:
(a) mixing at least water, stucco, and at least one extruded pregelatinized starch to form a slurry, wherein the extruded pregelatinized starch is formed by modifying and extruding a wet starch having a water content less than about 25% wherein the modifying at least partially hydrolyzes the starch via acid and/or enzyme modification,
(b) disposing the slurry between a first cover sheet and a second cover sheet to form a wet assembly,
(c) cutting the wet assembly into a board, and
(d) drying the board to form a set gypsum core between the first and second cover sheets;
the extruded pregelatinized starch having a cold water solubility greater than about 30% when measured at 25° C. and a cold water viscosity of a 10 wt. % slurry of the starch in water when measured at 25° C. and at a shear rate of 100 s −1 for 1 min is from about 120 centipoinse to about 300 centipoise;
the extruded pregelatinized starch causing the set gypsum core to have a compressive strength greater than an equivalent set gypsum core made with a starch having a cold water solubility less than about 30% instead of the extruded pregelatinized starch;
the board having a core hardness of at least about 11 lbs, as determined according to ASTM C473-10.
13. The method according to claim 12 , wherein the extruded pregelatinized starch has a cold water solubility from about 30% to about 75%.
14. The method according to claim 12 , wherein the extruded pregelatinized starch has a cold water solubility from about 50% to about 75%.
15. The method according to claim 13 , wherein the extruded pregelatinized starch has a particle size from about 100 microns to about 400 microns.
16. The method according to claim 12 , wherein the extruded pregelatinized starch is in the slurry in an amount from about 0.1% to about 5% by weight based on the weight of stucco.
17. The method according to claim 13 , wherein the extruded pregelatinized starch is in the slurry in an amount from about 0.1% to about 3% by weight based on the weight of stucco.
18. The method according to claim 15 , wherein the slurry further comprises sodium trimetaphosphate.
19. The method according to claim 16 , wherein the slurry further comprises sodium trimetaphosphate.
20. The method according to claim 17 , wherein the board has a density from about 24 pcf to about 35 pcf.