Light weight gypsum board

Patent metadata

Field	Value
Publication number	US-11338548-B2
Application number	US-201916518241-A
Country	US
Kind code	B2
Filing date	Jul 22, 2019
Priority date	Jun 9, 2005
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

This invention provides gypsum wallboards with a unique microstructure where the walls between voids are enhanced in thickness and strength to substantially improve the strength and handling properties of the wallboards. A method of making lightweight gypsum wallboards is also provided.

First claim

What is claimed is:

1. A light weight gypsum board comprising:
a set gypsum core disposed between two cover sheets;
the set gypsum core formed from a slurry comprising water, stucco, foam, pregelatinized starch, and naphthalenesulfonate dispersant;
the set gypsum core comprising a gypsum crystal matrix having walls defining and separating air voids within the gypsum crystal matrix, wherein the walls define:
(i) air voids with a size greater than about 100 microns in diameter,
(ii) air voids with a size from about 50 microns to about 100 microns in diameter, and
(iii) air voids with a size less than about 50 microns in diameter;

the majority of air voids, based on number of air voids, having a diameter of about 100 microns or less;
the average thickness of the walls between the air voids being about 30 microns to about 200 microns;
the average wall thickness and air voids measured using three-dimensional imaging acquired by X-ray CT-scanning analysis (XMT);
the gypsum crystal matrix formed such that the set gypsum core has an average core hardness of at least about 11 pounds as determined in accordance with ASTM C-473; and
and the board having a density of from about 24 pcf to about 33 pcf.

2. The light weight gypsum board of claim 1 , wherein the walls have an average thickness from about 70 microns to about 120 microns.

3. The light weight gypsum board of claim 1 , wherein the walls have an average thickness from about 30 microns to about 50 microns.

4. The light weight gypsum board of claim 3 , wherein the air voids with a size greater than about 100 microns in diameter comprise at least about 20% of the total void volume of the set gypsum core.

5. The light weight gypsum board of claim 3 , wherein the board has a density of from about 24 pcf to about 32 pcf.

6. The light weight gypsum board of claim 3 , wherein the board has a density of from about 24 pcf to about 31 pcf.

7. The light weight gypsum board of claim 3 , wherein at least a portion of the walls includes reinforced densified wall surfaces.

8. The light weight gypsum board of claim 3 , wherein the pregelatinized starch is in an amount from about 0.5% to about 10% by weight based on the weight of the stucco.

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

10. The light weight gypsum board of claim 8 , wherein the naphthalenesulfonate dispersant is in an amount from about 0.1% to about 3% by weight based on the weight of the stucco.

11. The light weight gypsum board of claim 10 , wherein the slurry further comprises sodium trimetaphosphate in an amount from about 0.1% to about 0.4% by weight based on the weight of the stucco.

12. A light weight gypsum board comprising:
a set gypsum core disposed between two cover sheets;
the set gypsum core formed from a slurry comprising water, stucco, foam, pregelatinized starch, and naphthalenesulfonate dispersant;
the set gypsum core comprising a gypsum crystal matrix having walls defining and separating air voids within the gypsum crystal matrix, wherein the walls define:
(i) air voids with a size greater than about 100 microns in diameter,
(ii) air voids with a size from about 50 microns to about 100 microns in diameter, and
(iii) air voids with a size less than about 50 microns in diameter;

the air void size having greatest frequency is a diameter of about 100 microns or less;
the average thickness of the walls between the air voids being about 30 microns to about 200 microns;
the average wall thickness and air voids measured using three-dimensional imaging acquired by X-ray CT-scanning analysis (XMT);
the gypsum crystal matrix formed such that the set gypsum core has an average core hardness of at least about 11 pounds as determined in accordance with ASTM C-473; and
and the board having a density of from about 24 pcf to about 33 pcf.

13. The light weight gypsum board of claim 12 , wherein the walls have an average thickness from about 70 microns to about 120 microns.

14. The light weight gypsum board of claim 12 , wherein the walls have an average thickness from about 30 microns to about 50 microns.

15. The light weight gypsum board of claim 14 , wherein the air voids with a size greater than about 100 microns in diameter comprise at least about 20% of the total void volume of the set gypsum core.

16. The light weight gypsum board of claim 14 , wherein the board has a density of from about 24 pcf to about 32 pcf.

17. The light weight gypsum board of claim 14 , wherein the board has a density of from about 24 pcf to about 31 pcf.

18. The light weight gypsum board of claim 14 , wherein at least a portion of the walls includes reinforced densified wall surfaces.

19. The light weight gypsum board of claim 14 , wherein the pregelatinized starch is in an amount from about 0.5% to about 10% by weight based on the weight of the stucco.

20. The light weight gypsum board of claim 14 , wherein the naphthalenesulfonate dispersant is in an amount from about 0.1% to about 3% by weight based on the weight of the stucco.

21. The light weight gypsum board of claim 19 , wherein the naphthalenesulfonate dispersant is in an amount from about 0.1% to about 3% by weight based on the weight of the stucco.

22. The light weight gypsum board of claim 21 , wherein the slurry further comprises sodium trimetaphosphate in an amount from about 0.1% to about 0.4% by weight based on the weight of the stucco.

23. A light weight gypsum board comprising:
a set gypsum core disposed between two cover sheets;
the set gypsum core formed from a slurry comprising water, stucco, foam, pregelatinized starch, and naphthalenesulfonate dispersant;
the set gypsum core comprising a gypsum crystal matrix having walls defining and separating air voids within the gypsum crystal matrix, wherein the walls define:
(i) air voids with a size greater than about 100 microns in diameter,
(ii) air voids with a size from about 50 microns to about 100 microns in diameter, and
(iii) air voids with a size less than about 50 microns in diameter;

the average air void size being less than about 100 microns in diameter;
the average thickness of the walls between the air voids being about 30 microns to about 200 microns;
the average wall thickness and air voids measured using three-dimensional imaging acquired by X-ray CT-scanning analysis (XMT);
the gypsum crystal matrix formed such that the set gypsum core has an average core hardness of at least about 11 pounds as determined in accordance with ASTM C-473; and
and the board having a density of from about 24 pcf to about 33 pcf.

24. The light weight gypsum board of claim 23 , wherein the walls have an average thickness from about 70 microns to about 120 microns.

25. The light weight gypsum board of claim 23 , wherein the walls have an average thickness from about 30 microns to about 50 microns.

26. The light weight gypsum board of claim 25 , wherein the air voids with a size greater than about 100 microns in diameter comprise at least about 20% of the total void volume of the set gypsum core.

27. The light weight gypsum board of claim 25 , wherein the board has a density of from about 24 pcf to about 32 pcf.

28. The light weight gypsum board of claim 25 , wherein the board has a density of from a

Assignees

• United States Gypsum Co

Inventors

• Yu Qiang
• Song Weixin D

Classifications

• C04B2111/0062

  Gypsum-paper board like materials · CPC title

• B32B29/00

  Layered products comprising {a layer of} paper or cardboard · CPC title

• B32B13/08 Primary

  of paper or cardboard · CPC title

• Y10T428/249968

  Of hydraulic-setting material · CPC title

• C04B2111/40

  Porous or lightweight materials · CPC title