Flour binder for gypsum board, and related methods, product, and slurries

Patent metadata

Field	Value
Publication number	US-11787739-B2
Application number	US-202017025003-A
Country	US
Kind code	B2
Filing date	Sep 18, 2020
Priority date	Nov 22, 2019
Publication date	Oct 17, 2023
Grant date	Oct 17, 2023

Abstract

Disclosed is an acid-modified flour and a method of making the acid-modified flour. The acid-modified flour is desirably prepared using a dry milling process. A starting flour is combined with a strong acid to form a mixture. The mixture is heated. A neutralizer is added to increase the pH of the mixture. If desired, the mixture can be dried and any agglomerates can be removed. The acid-modified flour can be used as a binder in a slurry for preparing one or more gypsum layers in a gypsum board.

First claim

The invention claimed is:

1. A method of making gypsum board comprising:
(a) forming an acid-modified flour by (i) combining starting flour from a dry milling process and a strong acid that substantially avoids chelating calcium ions to form a mixture, (ii) heating the mixture at a temperature of from about 50° C. to about 100° C., (iii) adding a neutralizer to the mixture to achieve a pH of from about 4.0 to about 7.5, and (iv) drying the mixture, the acid-modified flour having a hot water viscosity of from about 50 BU to about 420 BU, as measured according to the HWVA test;
(b) adding the acid-modified flour to at least water and stucco to form a slurry;
(c) disposing the slurry to form a gypsum board core between a first cover sheet and a second cover sheet to form a wet assembly;
(d) cutting the wet assembly into the gypsum board; and
(e) drying the gypsum board.

2. The method of claim 1 , wherein the mixture is dried after the neutralizer is added.

3. The method of claim 2 , further comprising removing agglomerates from the mixture, the agglomerates having a diameter of at least about 300 μm, wherein the agglomerates are removed before drying the mixture.

4. The method of claim 3 , wherein the gypsum board has a nail pull resistance of at least about 70 pounds-force according to ASTM 473-10, Method B and the gypsum board has a core hardness of at least 11 pounds.

5. The method of claim 2 , further comprising removing agglomerates from the mixture, the agglomerates having a diameter of at least about 300 μm, wherein the agglomerates are removed after drying the mixture.

6. The method of claim 2 , wherein the gypsum board has a nail pull resistance of at least about 70 pounds-force according to ASTM 473-10, Method B and the gypsum board has a core hardness of at least 11 pounds.

7. The method of claim 1 , wherein the gypsum board has a nail pull resistance of at least about 70 pounds-force according to ASTM 473-10, Method B and the gypsum board has a core hardness of at least 11 pounds.

8. The method of making board of claim 1 , wherein the mixture contains from about 97 wt. % to about 99.5 wt. % of the flour, and from about 0.5 wt. % to about 3 wt. % of the acid, wherein the weight percentages are in relation to the total weight of the mixture.

9. The method of claim 1 , wherein the starting flour is corn flour.

10. The method of claim 1 , wherein the neutralizer is sodium carbonate.

11. The method of claim 1 , further comprising removing agglomerates from the mixture, the agglomerates having a diameter of from about 300 μm to about 1000 μm, wherein the agglomerates are removed before drying the mixture.

12. The method of claim 1 , further comprising removing agglomerates from the mixture, the agglomerates having a diameter of from about 300 μm to about 1000 μm, wherein the agglomerates are removed after drying the mixture.

13. The method of claim 1 , further comprising removing agglomerates from the mixture, the agglomerates having a diameter of from about 300 μm to about 1000 μm, wherein:
the agglomerates are removed before or after drying the mixture, and
the gypsum board has a nail pull resistance of at least about 70 pounds-force according to ASTM 473-10, Method B and the gypsum board has a core hardness of at least 11 pounds.

14. A method of making board comprising:
(a) forming an acid-modified flour by (i) combining starting corn flour obtained from a dry milling process and a sulfuric acid to form a mixture, (ii) heating the mixture at a temperature of from about 50° C. to about 100° C., (iii) adding sodium carbonate to the mixture to achieve a pH of from about 4.0 to about 7.5 to form the acid-modified flour, (iv) filtering large agglomerates having a size of at least about 300 μm, and (v) drying the mixture, the acid-modified flour having a hot water viscosity of from about 50 BU to about 420 BU, as measured according to the HWVA test;
(b) adding the acid-modified flour to at least water and stucco to form a slurry;
(c) disposing the slurry to form a board core between a first cover sheet and a second cover sheet to form a wet assembly;
(d) cutting the wet assembly into a board; and
(e) drying the board.

15. The method of making board of claim 14 , wherein the mixture contains from about 97 wt. % to about 99.5 wt. % of the flour, and from about 0.5 wt. % to about 3 wt. % of the acid, wherein the weight percentages are in relation to the total weight of the mixture.

16. The method of claim 15 , wherein the gypsum board has a nail pull resistance of at least about 70 pounds-force according to ASTM 473-10, Method B and the gypsum board has a core hardness of at least 11 pounds.

17. The method of claim 14 , wherein
the mixture is dried after the neutralizer is added, and
the gypsum board has a nail pull resistance of at least about 70 pounds-force according to ASTM 473-10, Method B and the gypsum board has a core hardness of at least 11 pounds.

Assignees

• United States Gypsum Co

Inventors

• Sang Yijun
• Hemphill Mark

Classifications

• C04B20/023

  Chemical treatment · CPC title

• B32B37/15

  with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state · CPC title

• B32B2309/02

  Temperature · CPC title

• E04C2/049

  completely or partially of insulating material, e.g. cellular concrete or foamed plaster · CPC title

• B32B38/0036

  Heat treatment (for heating or cooling of layers during lamination B32B37/06, B32B37/08) · CPC title