Cementitious article and method for preparing the same

• US 8,329,308 B2
• Filed: 03/31/2009
• Issued: 12/11/2012
• 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: Liu, Qingxia, Shake, Michael P., Yu, Qiang
• Primary Examiner(s): Ahmed, Sheeba
• Application Number:
  US12/415,931
• Publication Number:
  US 20100247937A1
• Time in Patent Office: 1,351 Days
• Field of Search: None
• 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, wherein the cementitious slurry comprises;

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

(ii) polyvinyl acetate or polyvinyl alcohol polymer or copolymer present in an amount of from about 0.1% to about 2% by weight of the cementitious slurry;

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

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

(b) depositing the cementitious slurry onto an advancing sheet of facer material; and

(c) allowing the slurry to set.

2. The method of claim 1, wherein the facer material comprises glass fiber, polymer fiber, mineral fiber, organic fiber, or a combination thereof.

3. A cementitious article comprising:

(a) a cementitious component that (i) comprises a cementitious material, a polyvinyl acetate or polyvinyl alcohol polymer or copolymer, a monobasic phosphate, and optionally boric acid;

(ii) is formed from a slurry that comprises a cementitious material, a polyvinyl acetate or polyvinyl alcohol polymer or copolymer, a monobasic phosphate, and optionally boric acid;

or both (i) and (ii); 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 or polyvinyl alcohol polymer or copolymer, 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 or polyvinyl alcohol polymer or copolymer, monobasic phosphate, and boric acid in the central region of the component; and

(c) at least one facer layer for supporting the component.

4. The cementitious article of claim 3, the facer layer comprising glass fiber, polymer fiber, mineral fiber, organic fiber, or a combination thereof.

5. The cementitious article of claim 4, further comprising at least one dense layer optionally comprising a polyvinyl acetate or polyvinyl alcohol polymer or copolymer, a monobasic phosphate, and optionally boric acid, wherein the dense layer is disposed between the component and the at least one facer layer.

6. A method of preparing a cementitious article comprising:

(a) preparing a cementitious slurry, the cementitious slurry comprising cementitious material, a polyvinyl acetate or polyvinyl alcohol polymer or copolymer, a monobasic phosphate, about 0.1-0.5 wt. % boric acid, and water; and

(b) allowing the slurry to set.

7. The method of claim 6, further comprising depositing the cementitious slurry on a facer layer for supporting the component, the facer layer comprising glass fiber, polymer fiber, mineral fiber, organic fiber, or a combination thereof.

8. A cementitious article comprising a cementitious component, wherein the cementitous component (i) comprises a cementitious material, a polyvinyl acetate or polyvinyl alcohol polymer or copolymer, a monobasic phosphate, and about 0.1-0.5 wt. % boric acid;

(ii) is formed from a slurry that comprises a cementitious material, a polyvinyl acetate or polyvinyl alcohol polymer or copolymer, about 0.1-1 wt. % of a monobasic phosphate, and about 0.1-0.5 wt. % boric acid;

or both (i) and (ii).