Pregelatinized starch with mid-range viscosity, and product, slurry and methods related thereto

Patent metadata

Field	Value
Publication number	US-9540810-B2
Application number	US-201314044582-A
Country	US
Kind code	B2
Filing date	Oct 2, 2013
Priority date	Oct 23, 2012
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

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.

First claim

The invention claimed is:

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.

Assignees

• United States Gypsum Co

Inventors

• Sang Yijun
• Lee Chris C
• Chan Cesar
• Song Weixin David

Classifications

• C08B30/14

  Cold water dispersible or pregelatinised starch · CPC title

• E04C2/043 Primary

  of plaster (E04C2/049 takes precedence) · CPC title

• C08L3/02

  Starch; Degradation products thereof, e.g. dextrin · CPC title

• C04B28/14 Primary

  containing calcium sulfate cements {(gypsum-paper plates E04C)} · CPC title

• C09J103/08

  Ethers · CPC title