PARTICLE STABILIZED FOAM, AND SLURRIES, PRODUCT, AND METHODS RELATED THERETO

• US 20140272376A1
• Filed: 09/18/2013
• Published: 09/18/2014
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Original Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Inventors: DUBEY, Ashish, ALDABAIBEH, Naser, NATESAIYER, Kumar
• Granted Patent: US 9,540,287 B2
• Time in Patent Office: Days
• US Class Current: 428/312.4
• CPC Class Codes: B29D 99/0021 provided with plain or filled structures, e.g. cores, placed between two or more plates or sheets, e.g. in a matrix
• CPC Class Codes: C04B 2103/0094 Agents for altering or buffering the pH; Ingredients characterised by their pH
• CPC Class Codes: C04B 2103/40 Surface-active agents, dispersants
• CPC Class Codes: C04B 24/02 Alcohols; Phenols; Ethers
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 28/14 containing calcium sulfate cements gypsum-paper plates E04C
• CPC Class Codes: C04B 38/10 by using foaming agents C04B38/02 takes precedenceor by using mechanical means, e.g. adding preformed foam
• CPC Class Codes: E04B 1/167 with permanent forms made of particular materials, e.g. layered products
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10T 428/249968 Of hydraulic-setting material

Abstract

Disclosed are cementitious product, as well as cementitious slurry, and method of forming the product. To reduce density in the cementitious product, foam is included in the slurry and in the method of forming the product. The slurry includes cementitious particles, water, and air bubbles such as from compressed air. Instead of using detergent chemistry at the gas/water interface of bubbles, the present invention uses a surface modifying agent for the cementitious particles in the slurry. The modified particles act to produce stable foam in the slurry. As an example mode of introduction, the surface modifier can be added (e.g., as solid or solution) directly into a bulk cementitious slurry that forms the product. As another example, the surface modifier can be added in a separate solution with water, air bubbles, and cementitious particles that serve as additive to the main cementitious slurry, where the separate solution is then added to the main cementitious slurry.

Claims

1. A slurry for forming a product, the slurry comprising:

(a) water;

(b) cementitious particles;

(c) air bubbles with walls formed by the water; and

(d) surface modifying agent effective to modify a surface of at least some of the cementitious particles, such that the modified particles stabilize the air bubbles sufficiently to form air voids in the product.

2. The slurry of claim 1, wherein the slurry has a pH of at least about 7.5.

3. The slurry of claim 1, wherein the slurry is substantially free of detergent surfactant.

4. The slurry of claim 1, wherein the cementitious particles comprise stucco, calcium sulfate dihydrate, Portland cement, fly ash, or combinations thereof.

5. The slurry of claim 1, wherein the cementitious particles are hydrophilic and the surface modifying agent is a hydrophobicity imparting agent for rendering the cementitious particles at least partially hydrophobic.

6. The slurry of claim 1, wherein the surface modifying agent comprises one or more gallate compound of Formula I:

7. The slurry of claim 6, wherein R is characterized as C₁-C₆ alkyl, C₁-C₆ alkenyl, C₁-C₆ alkynyl, C₃-C₈ cycloalkyl, C₃-C₈ cycloalkenyl, C₆-C₈ aryl, wherein the alkyl, alkenyl, and alkynyl groups are branched or unbranched, and optionally substituted with one or more substituents selected from halo, alkoxy, ester, or substituted amide.

8. The slurry of claim 6, wherein R is C₁-C₆ alkyl.

9. The slurry of claim 1, wherein the surface modifying agent is propyl gallate.

10. The slurry of claim 1, wherein the surface modifying agent is present in an amount from about 0.1% to about 7% by weight of the cementitious particles.

11. The slurry of claim 1, further comprising starch in an amount from about 0.1% to about 10% by weight of the cementitious particles.

12. The slurry of claim 1, wherein the cementitious particles comprise heat resistant accelerator and wherein the slurry further comprises starch.

13. A cementitious product comprising:

porous cementitious component formed from a slurry comprising water, cementitious particles, air bubbles with walls formed from the water, and surface modifying agent effective to modify a surface of at least some of the cementitious particles, such that the particles stabilize the air bubbles sufficiently to form air voids in the component.

14. The product of claim 13, wherein the product is gypsum drywall, acoustical tile, floor underlayment, floor capping, mold-resistant board, cement board, or exterior sheathing.

15. A gypsum product comprising:

a set gypsum containing composition formed from a slurry comprising water, stucco particles, air bubbles with walls formed by the water, and surface modifying agent effective to modify a surface of at least some of the stucco particles, such that the particles stabilize the air bubbles sufficiently to form air voids in the product, the set gypsum composition comprising a gypsum crystal matrix.

16. The gypsum product of claim 15, wherein the set gypsum composition is disposed between two cover sheets to form a board, wherein the board has a density of about 35 pcf or less.

17. The gypsum product of claim 15, wherein the slurry further comprises a starch, polyphosphate, dispersant, or combination thereof.

18. A method of making gypsum board comprising:

(a) mixing at least water, air, cementitious particles, and surface modifying agent, such that bubbles of the air surrounded by walls formed from the water are created, and such that the surface modifying agent is effective to modify a surface of at least some of the cementitious particles to stabilize the bubbles sufficiently to form a foamed slurry which can be optionally combined with a second cementitious slurry to form an optional combined foamed slurry;

(b) disposing the foamed slurry or combined slurry between a first cover sheet and a second cover sheet to form a board precursor;

(c) cutting the board precursor into a board; and

(d) drying the board.

19. The method of claim 18, wherein the cementitious particles comprise stucco.

20. The method of claim 18, wherein:

(i) the cementitious particles are heat resistant accelerator,

(ii) the slurry is combined with the second slurry,

(iii) the second slurry comprises stucco, water, and optionally other additives,

and

(iv) the slurry of step (b) is the combined slurry.

21. The method of claim 18, wherein:

the foamed cementitious slurry comprises heat resistant accelerator cementitious particles;

the second cementitious slurry is an aqueous dispersion of calcined gypsum formed in a main mixer chamber;

the second cementitious slurry is discharged from the main mixer chamber into a discharge apparatus; and

the foamed cementitious slurry is introduced into the discharge apparatus.