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

Patent metadata

Field	Value
Publication number	US-10399899-B2
Application number	US-201313835002-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Oct 23, 2012
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

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).

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 pregelatinized partially hydrolyzed starch, wherein the hydrolysis at least partially depolymerizes the starch via acid and/or enzyme modification, wherein the pregelatinized partially hydrolyzed starch has a characteristic of a viscosity from about 35 centipoise to about 425 centipoise when the viscosity is measured while the pregelatinized partially hydrolyzed starch is subjected to conditions according to VMA method;
wherein the pregelatinized partially hydrolyzed starch is in an amount from about 0.5% to about 5% by weight of the stucco;
the slurry requiring an increase in water demand to maintain a slurry fluidity at the same level that it would be without the pregelatinized partially hydrolyzed starch that is less than the increase in water demand required by an otherwise identical slurry containing a starch having a viscosity above 425 centipoise according to the VMA method instead of the pregelatinized partially hydrolyzed starch;
the board having a core hardness of at least about 11 lb, as determined according to ASTM C473-10.

2. The board according to claim 1 , wherein the viscosity characteristic of the pregelatinized partially hydrolyzed starch is from about 35 centipoise to about 200 centipoise according to the VMA method.

3. The board according to claim 1 , wherein the pregelatinized partially hydrolyzed starch is effective to increase a core hardness of the set gypsum core relative to the set gypsum core without the pregelatinized partially hydrolyzed starch.

4. The board according to claim 1 , wherein the pregelatinized partially hydrolyzed starch is acid-modified by sulfuric acid.

5. The board according to claim 1 , wherein the slurry has a water/stucco ratio from about 0.55 to about 0.8.

6. The board according to claim 1 , wherein the board has a density from about 24 pcf to about 35 pcf.

7. The board according to claim 1 , wherein the slurry comprises a second type of starch that is (a) not gelatinized, (b) is a pregelatinized starch having the characteristic of a viscosity below 35 centipoise according to the VMA method, (c) is a pregelatinized starch having the characteristic of viscosity above 425 centipoise according to the VMA method, and/or (d) is not partially hydrolyzed.

8. The board according to claim 7 , wherein the second type of starch comprises alkylated starch.

9. The board according to claim 8 , wherein the second type of starch comprises ethylated starch.

10. The board according to claim 1 , wherein the slurry further comprises at least one foaming agent comprising a major weight portion of unstable component and a minor weight portion of stable component, an amount of foaming agent and a weight ratio of the unstable component to stable component effective to form a void distribution within the set gypsum core.

11. The board according to claim 1 , wherein the slurry further comprises naphthalenesulfonate dispersant.

12. The board according to claim 11 , wherein the naphthalenesulfonate dispersant is in an amount from about 0.1% to about 3% by weight based on weight of the stucco.

13. The board according to claim 1 , wherein the slurry further comprises sodium trimetaphosphate.

14. The board according to claim 13 , wherein the sodium trimetaphosphate is in an amount from about 0.12% to about 0.4% by weight of the stucco.

15. The board according to claim 1 , wherein the pregelatinized partially hydrolyzed starch is a flour that contains starch.

16. The board according to claim 1 , wherein the pregelatinized partially hydrolyzed starch is partially pregelatinized.

17. The board according to claim 1 , wherein, when the board is cast at a thickness of about ½ inch, the board has a nail pull resistance of at least about 65 pounds, as determined according to ASTM standard C473.

18. A slurry comprising water, stucco, and at least one pregelatinized partially hydrolyzed starch, wherein the hydrolysis at least partially depolymerizes the starch via acid and/or enzyme modification, wherein the pregelatinized partially hydrolyzed starch has a characteristic of viscosity from about 35 centipoise to about 425 centipoise when the viscosity is measured while the pregelatinized partially hydrolyzed starch is subjected to conditions according to VMA method;
wherein the pregelatinized partially hydrolyzed starch is in an amount from about 0.5% to about 5% by weight of the stucco;
the slurry requiring an increase in water demand to maintain a slurry fluidity at the same level that it would be without the pregelatinized partially hydrolyzed starch that is less than the increase in water demand required by an otherwise identical slurry containing a starch having a viscosity above 425 centipoise according to the VMA method instead of the pregelatinized partially hydrolyzed starch;
wherein when the slurry is used to make a board, the board has a core hardness of at least about 11 lb, as determined according to ASTM C473-10.

19. A product made from the slurry of claim 18 .

20. An acoustical panel comprising an acoustical component comprising fiber and the slurry of claim 18 .

21. The acoustical panel according to claim 20 , wherein the fiber comprises mineral wool.

22. A method of making board comprising:
(a) mixing at least water, stucco, and at least one pregelatinized partially hydrolyzed starch to form a slurry, wherein the hydrolysis at least partially depolymerizes the starch via acid and/or enzyme modification, wherein the pregelatinized partially hydrolyzed starch has a characteristic of a viscosity from about 35 centipoise to about 425 centipoise when the viscosity is measured according to the VMA method;
wherein the pregelatinized partially hydrolyzed starch is in an amount from about 0.5% to about 5% by weight of the stucco;
the slurry requiring an increase in water demand to maintain a slurry fluidity at the same level that it would be without the pregelatinized partially hydrolyzed starch that is less than the increase in water demand required by an otherwise identical slurry containing a starch having a viscosity above 425 centipoise according to the VMA method instead of the pregelatinized partially hydrolyzed starch;
(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, the board having a core hardness of at least about 11 lb, as determined according to ASTM C473-10.

23. The method of claim 22 , wherein the pregelatinized partially hydrolyzed starch is partially gelatinized when added to the slurry, with additional gelatinization taking place in the drying step (d).

24. The method of claim 22 , wherein the pregelatinized partially hydrolyzed starch becomes fully gelatinized in the drying step (d).

25. The method of claim 22 , wherein the pregelatinized partially hydrolyzed starch is fully gelatinized when added to the slurry.

26. The method of claim 22 , further comprising gelatinizing the pregelatinized partially hydrolyzed starch at or above the pregelatinized partially hydrolyzed starch's gelatinization temperature for at least about 10 minutes prior to adding it to the slurry.

27. A board comprising:
a set gypsum core disposed between two cover sheets, the c

Assignees

• United States Gypsum Co

Inventors

• Sang Yijun
• Song Weixin D

Classifications

• Y10T428/31971

  Of carbohydrate · CPC title

• C04B28/14

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

• C04B2111/0062

  Gypsum-paper board like materials · CPC title

• C04B2103/40

  Surface-active agents, dispersants · CPC title

• C04B2103/10

  Accelerators; Activators · CPC title