Composite gypsum board and methods related thereto

Patent metadata

Field	Value
Publication number	US-2016375655-A1
Application number	US-201615186176-A
Country	US
Kind code	A1
Filing date	Jun 17, 2016
Priority date	Jun 24, 2015
Publication date	Dec 29, 2016
Grant date	—

Abstract

Disclosed is a composite gypsum board comprising a board core and a concentrated layer of substantial thickness (e.g., at least about 0.02 inches). The concentrated layer includes a higher weight percentage of an enhancing additive than the board core. The board core has a thickness greater than the thickness of the concentrated layer and forms the bulk of the board volume. The concentrated layer has a higher density (e.g., at least about 1.1 times greater) than the density of the board core. Also disclosed is a method of preparing a composite gypsum board.

First claim

1 . A composite gypsum board comprising:
(a) a board core comprising set gypsum formed from at least water, stucco, and optionally, an enhancing additive, the core having a dry density and dry thickness, the core defining first and second core faces in opposing relation; and (b) a concentrated layer formed from at least water, stucco, and the enhancing additive, the concentrated layer disposed in bonding relation to the first core face, the concentrated layer having a dry density of at least about 1.1 times higher than the dry density of the board core; wherein:
(i) when the enhancing additive is present in forming the core, the enhancing additive is included in a higher concentration in forming the concentrated layer than in forming the board core, and
(ii) the board core dry thickness is greater than a dry thickness of the concentrated layer.

2 . The composite gypsum board of claim 1 , wherein:
the concentrated layer defines first and second concentrated layer faces, the board further comprises a top cover sheet, the first concentrated layer face facing the top cover sheet, and the second concentrated layer face faces the first core face.

3 . The composite gypsum board of claim 1 , wherein the board further comprises a bottom cover sheet, the second core face facing the bottom cover sheet.

4 . The composite gypsum board of claim 3 , wherein the top and/or bottom cover sheet has a thickness of at least about 0.014 inches (about 0.036 cm).

5 . The composite gypsum board of claim 3 , wherein the top and/or bottom cover sheet is formed from paper and has a paper basis weight from about 38 lbs/MSF (about 185 g/m 2 ) to about 58 lbs/MSF (about 283 g/m 2 ).

6 . The composite gypsum board of claim 3 , wherein the top and/or bottom cover sheet has a density from about 38 pcf (about 610 kg/m 3 ) to about 42 pcf (about 670 kg/m 3 ).

7 . The composite gypsum board of claim 1 , wherein the dry density of the concentrated layer is from about 36 pcf (about 580 kg/m 3 ) to about 45 pcf (about 720 kg/m 3 ).

8 . The composite gypsum board of claim 1 , wherein the dry thickness of the concentrated layer is from about 0.035 inches (about 0.09 cm) to about 0.05 inches (about 0.13 cm).

9 . The composite gypsum board of claim 1 , wherein the dry density of the board core is from about 24 pcf (about 380 kg/m 3 ) to about 40 pcf (about 640 kg/m 3 ).

10 . The composite gypsum board of claim 1 , wherein the dry thickness of the board core is from about 9 times to about 14 times thicker than the thickness of the concentrated layer.

11 . The composite gypsum board of claim 1 , wherein the enhancing additive comprises starch.

12 . The composite gypsum board of claim 11 , wherein the starch includes hydroxyethylated or hydroxypropylated starch, or a combination thereof.

13 . The composite gypsum board of claim 1 , wherein the starch includes pregelatinized starch.

14 . The composite gypsum board of claim 13 , the pregelatinized starch having a viscosity of from about 20 centipoise to about 700 centipoise when the viscosity is measured while the starch is subjected to conditions according to the VMA method.

15 . The composite gypsum board of claim 14 , the pregelatinized starch having a viscosity of from about 30 centipoise to about 200 centipoise according to the VMA method.

16 . The composite gypsum board of claim 13 , wherein the starch is included in forming the concentrated layer in an amount of from about 5% to about 40% by weight of the stucco and is included in forming the board core in an amount of from about 0% to about 4% by weight of the stucco.

17 . The composite gypsum board of claim 1 , wherein the enhancing additive comprises polyvinyl alcohol and/or boric acid.

18 . The composite gypsum board of claim 17 , wherein the enhancing additive includes polyvinyl alcohol and the polyvinyl alcohol is present in the concentrated layer in an amount from about 1% to about 5% by weight of the stucco, and is present in the board core in an amount from about 0% to about 1% by weight of the stucco.

19 . The composite gypsum board of claim 17 , wherein the enhancing additive includes boric acid, and the boric acid is present in the concentrated layer in an amount of from about 0.1% to about 1% by weight of the stucco, and is present in the board core in an amount from about 0% to about 0.1% by weight of the stucco.

20 . The composite gypsum board of claim 1 , wherein the enhancing additive comprises nano-cellulose, micro-cellulose, or any combination thereof.

21 . The composite gypsum board of claim 20 , wherein the nano-cellulose, micro-cellulose, or any combination thereof is present in the concentrated layer in an amount from about 0.05% to about 1% by weight of the stucco, and is present in the in the board core in an amount from about 0% to about 0.01% by weight of the stucco.

22 . The composite gypsum board of claim 1 , wherein the enhancing additive comprises gypsum-cement.

23 . The composite gypsum board of claim 22 , wherein the gypsum-cement is included in forming the concentrated layer in an amount of from about 5% to about 30% by weight of the stucco, and is included in forming the board core in an amount of from about 0% to about 10% by weight of the stucco.

24 . The composite gypsum board of claim 1 , wherein the core and/or the concentrated layer is further formed from a polyphosphate.

25 . The composite gypsum board of claim 24 , wherein the polyphosphate is sodium trimetaphosphate, potassium trimetaphosphate, ammonium trimetaphosphate, lithium trimetaphosphate or any combination thereof.

26 . The composite gypsum board of claim 25 , wherein the polyphosphate is included in forming the concentrated layer in an amount of from about 0.2% to about 0.4% by weight of the stucco, and is included in forming the board core in an amount of from about 0% to about 0.2% by weight of the stucco.

27 . The composite gypsum board of claim 1 , wherein the core and/or the concentrated layer is further formed from a dispersant.

28 . The composite gypsum board of claim 27 , wherein the dispersant is a naphthalenesulfonate, polycarboxylate, lignosulfonate, sulfonated lignin, or any combination thereof.

29 . The composite gypsum board of claim 27 , wherein the dispersant is included in forming the concentrated layer in an amount from about 0.1% to about 0.2% by weight of the stucco, and is included in forming the board core in an amount of from about 0% to about 0.4% by weight of the stucco.

30 . The composite gypsum board of claim 1 , wherein the board has a nail pull resistance according to ASTM C473-10, Method B of at least about 68 lbs of force.

31 . The composite gypsum board of claim 1 , wherein the concentrated layer has an average core hardness that is at least about 4 times greater than the average core hardness of the board core, wherein the average core hardness is measured according to ASTM C-473-10.

32 . The composite gypsum board of claim 1 , wherein the water and stucco for forming the board core are in a water-stucco ratio of from about 0.3 to about 0.7.

33 . The composite gypsum board of any claim 1 , wherein the water and stucco for forming the concentrated layer are in a water-stucco ratio of from about 0.7 to about 2.0.

Assignees

• United States Gypsum Co

Inventors

• Li Alfred C
• Song Weixin D
• Sang Yijun
• Diefenbacher Gregg G
• Vilinska Annamaria
• Christ Brian J
• Jones Fredrick T
• Todd Bradley W

Classifications

• B32B13/14

  next to a fibrous or filamentary layer · CPC title

• C04B2111/0062

  Gypsum-paper board like materials · CPC title

• C04B28/14

  containing calcium sulfate cements {(gypsum-paper plates E04C)} · CPC title

• B32B2264/02

  Synthetic macromolecular particles · CPC title

• B32B2307/50

  having particular mechanical properties · CPC title