CEMENTITIOUS ARTICLE AND METHOD FOR PREPARING THE SAME

• US 20100247937A1
• Filed: 03/31/2009
• Published: 09/30/2010
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Original Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Inventors: SHAKE, Michael P., LIU, Qingxia, YU, Qiang
• Granted Patent: US 8,329,308 B2
• Time in Patent Office: Days
• US Class Current: 428/500
• CPC Class Codes: C04B 14/42 Glass
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 2103/12 Set accelerators
• CPC Class Codes: C04B 2103/22 Set retarders
• CPC Class Codes: C04B 2103/408 Dispersants
• CPC Class Codes: C04B 2103/67 Biocides
• CPC Class Codes: C04B 2111/00482 Coating or impregnation materials
• CPC Class Codes: C04B 2111/0062 Gypsum-paper board like materials
• CPC Class Codes: C04B 2111/00672 Pointing or jointing materials
• CPC Class Codes: C04B 2111/60 Flooring materials
• CPC Class Codes: C04B 22/0013 Boron compounds
• CPC Class Codes: C04B 22/16 containing phosphorus in the anion, e.g. phosphates
• CPC Class Codes: C04B 24/2623 Polyvinylalcohols; Polyvinylacetates
• CPC Class Codes: C04B 24/38 Polysaccharides or derivatives thereof C04B24/243 takes precedence
• CPC Class Codes: C04B 24/42 Organo-silicon compounds
• CPC Class Codes: C04B 28/14 containing calcium sulfate cements gypsum-paper plates E04C
• CPC Class Codes: C04B 38/106 by adding preformed foams
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

A cementitious article and a method of making a cementitious article are disclosed. The cementitious article comprises a cementitious component that comprises a polyvinyl acetate type polymer, a monobasic phosphate, and optionally boric acid. Cementitious articles, such as board, are prepared such that the polyvinyl acetate type polymer, the monobasic phosphate, and optionally boric acid can be present in the cementitious core, and/or in dense layers if present. The concentration of the polyvinyl acetate type polymer, monobasic phosphate, and optionally boric acid in the cementitious article can increase from a central region A to peripheral regions B and C, respectively. In some embodiments, the polyvinyl acetate type polymer is a polyvinyl alcohol and the monobasic phosphate is monoammonium phosphate.

Claims

1. A method of preparing a cementitious article comprising:

(a) preparing a cementitious slurry, the cementitious slurry comprising cementitious material, a polyvinyl acetate type polymer, a monobasic phosphate, optionally boric acid, and water; and

(b) allowing the slurry to set.

2. The method of claim 1, further comprising depositing the cementitious slurry onto an advancing sheet of facer material.

3. The method of claim 2, wherein the facer material comprises glass fiber, polymer fiber, mineral fiber, organic fiber, or a combination thereof.

4. The method of claim 1, wherein the cementitious material comprises calcined gypsum.

5. The method of claim 1, wherein the polyvinyl acetate type polymer is selected from the group consisting of polyvinyl acetate, polyvinyl alcohol, polyvinyl alcohol copolymer, polyvinyl acetate copolymer, or a combination thereof, and wherein the monobasic phosphate is selected from the group consisting of monoammonium phosphate, monopotassium phosphate, monosodium phosphate, monolithium phosphate, or a combination thereof.

6. The method of claim 1, wherein the polyvinyl acetate type polymer is polyvinyl alcohol, and wherein the monobasic phosphate is monoammonium phosphate.

7. The method of claim 1, wherein the cementitious slurry forms a core of the article.

8. The method of claim 1, wherein the cementitious slurry forms a dense layer of the article.

9. The method of claim 8, further comprising depositing a cementitious slurry layer over the dense layer, wherein the cementitious slurry layer over the dense layer forms a core of the article and optionally comprises one or more of a polyvinyl acetate type polymer, boric acid, and a monobasic phosphate.

10. The method of claim 1, wherein the cementitious slurry forms at least one outer layer of the article.

11. The method of claim 1, wherein the cementitious slurry further comprises silicone based material and/or polyphosphate.

12. The method of claim 1, wherein the cementitious slurry comprises:

(a) cementitious material present in an amount of at least about 50% by weight of the cementitious slurry;

(b) polyvinyl acetate type polymer present in an amount of from about 0.1% to about 2% by weight of the cementitious slurry;

(c) boric acid present in an amount of from about 0.1% to about 1% by weight of the cementitious slurry; and

(d) monobasic phosphate present in an amount of from about 0.1% to about 1% by weight of the cementitious slurry.

13. The method of claim 12, wherein the facer material comprises glass fiber, polymer fiber, mineral fiber, organic fiber, or a combination thereof.

14. A cementitious article comprising a polyvinyl acetate type polymer a monobasic phosphate, and optionally boric acid, prepared according to the method of claim 1.

15. A cementitious article comprising:

(a) a cementitious component comprising a cementitious material, a polyvinyl acetate type polymer, a monobasic phosphate, and optionally boric acid; and

(b) a first surface of the component, a second surface of the component, and a central region of the component, overlapping a central axis, halfway between the first surface and the second surface;

wherein the total concentration of the polyvinyl acetate type polymer, monobasic phosphate, and optionally boric acid, in one or both regions in the component adjacent the first and second surfaces, respectively, is greater than the total concentration of the polyvinyl acetate type polymer, monobasic phosphate, and boric acid in the central region of the component.

16. The cementitious article of claim 15, further comprising at least one facer layer for supporting the component, the facer layer comprising glass fiber, polymer fiber, mineral fiber, organic fiber, or a combination thereof.

17. The cementitious article of claim 16, further comprising at least one dense layer optionally comprising a polyvinyl acetate type polymer, a monobasic phosphate, and optionally boric acid, wherein the dense layer(s) is disposed between the component and the at least one facer layer.

18. A cementitious article comprising:

a cementitious component comprising a cementitious material, a polyvinyl acetate type polymer, and a monobasic phosphate, and optionally boric acid.

19. The cementitious article of claim 18, wherein the cementitious material comprises calcined gypsum.

20. The cementitious article of claim 18, further comprising at least one facer layer for supporting the component, the facer layer comprising glass fiber, polymer fiber, mineral fiber, organic fiber, or a combination thereof.

21. The cementitious article of claim 20, further comprising at least one dense layer optionally comprising one or more of a polyvinyl acetate type polymer, a monobasic phosphate, and boric acid, wherein the dense layer(s) is disposed between the component and at least one facer layer.

22. The cementitious article of claim 18, wherein the polyvinyl acetate type polymer is selected from the group consisting of polyvinyl acetate, polyvinyl alcohol, polyvinyl alcohol copolymer, polyvinyl acetate copolymer, and combinations thereof, and wherein the monobasic phosphate is selected from the group consisting of monoammonium phosphate, monopotassium phosphate, monosodium phosphate, monolithium phosphate, and combinations thereof.

23. The cementitious article of claim 22, wherein the monobasic phosphate is monoammonium phosphate, and wherein the polyvinyl acetate type polymer is polyvinyl alcohol.

24. The cementitious article of claim 18, wherein the polyvinyl acetate type polymer, monobasic phosphate and optional boric acid are added to the component during setting of the cementitious material or in a post-set treatment.