Building board and method of forming the building board

Patent metadata

Field	Value
Publication number	US-2017284093-A1
Application number	US-201715476786-A
Country	US
Kind code	A1
Filing date	Mar 31, 2017
Priority date	Apr 1, 2016
Publication date	Oct 5, 2017
Grant date	—

Abstract

A building board including a cementitious layer between two fiber mats. At least one fiber mat forms with a polymer film a fiber mat/polymer film laminate. The cementitious layer of the building board contains a reactive water-insoluble polymer which improves binding of the fiber mat/polymer film laminate to the cementitious layer. The building board has a low water absorption and a high level surface finish.

First claim

1 . A building board comprising:
a cementitious layer between a first fiber mat and a second fiber mat, the first fiber mat and the second fiber mat being at least partially embedded in the cementitious layer, the first fiber mat having a first surface and a second surface opposite the first surface, and the second fiber mat is closer to the first surface than to the second surface; a first adhesive layer directly attached to the second surface of the first fiber mat; and a first polymer film attached to an outer surface of the first adhesive layer, wherein the cementitious layer comprises a reactive water-insoluble polymer adapted for binding the first fiber mat and the second fiber mat to the cementitious layer.

2 . The building board according to claim 1 , wherein the cementitious layer comprises a first cementitious layer, a second cementitious layer, and a core cementitious layer between the first cementitious layer and the second cementitious layer; and wherein the core cementitious layer is essentially free of reactive water-insoluble polymer, and the first cementitious layer and the second cementitious layer include the reactive water-insoluble polymer.

3 . The building board according to claim 1 , further comprising a second adhesive layer and a second polymer film, wherein:
the second fiber mat has a first surface and a second surface opposite the first surface, the first fiber mat being closer to the first surface of the second fiber mat than the second surface of the second fiber mat, the second adhesive layer attached to the second surface of the second fiber mat, and the second polymer film attached to an outer surface of the second adhesive layer.

4 . The building board according to claim 1 , wherein the building board has a water absorption of not greater than 10 wt % based on the total weight of the building board after 2-hour immersion as per ASTM C 473-13.

5 . The building board according to claim 1 , further comprising a coating layer directly attached to an outer surface of the first polymer film, an outer surface of the second polymer film, or both the outer surface first polymer film and the outer surface of the second polymer film.

6 . The building board according to claim 1 , wherein an exterior surface of the building board has an average surface roughness of not greater than 20 microns.

7 . The building board according to claim 1 , wherein the reactive water-insoluble polymer includes an emulsion polymer.

8 . The building board according to claim 1 , wherein the reactive water-insoluble polymer includes a vinyl acetate ethylene copolymer, a styrene acrylic copolymer, an acrylic copolymer, or any combination thereof.

9 . The building board according to claim 7 , wherein the reactive water insoluble polymer is present in an amount of at least 0.5 wt % and not greater than 8 wt % based on the total weight of the first cementitious layer or the second cementitious layer.

10 . The building board according to claim 1 , wherein the cementitious layer includes gypsum, Portland cement, magnesium oxide, magnesium phosphate, or any combination thereof.

11 . The building board according to claim 1 , wherein the first polymer film, the second polymer film, or the first polymer film and the second polymer film is a melt-extruded film having a thickness of at least 5 microns and not greater than 100 microns.

12 . The building board according to claim 1 , wherein the first polymer film, the second polymer film, or the first polymer film and the second polymer film includes a polyethylene, a polypropylene, a polyamide, a polyamide imide, a polyester, a polycarbonate, a polyether, a polyether ketone, a polyether ether ketone, an acryl copolymer, a butadiene copolymer, a styrene copolymer, or any combination thereof.

13 . The building board according to claim 12 , wherein the first polymer film consists essentially of polyethylene terephthalate.

14 . The building board according to claim 2 , wherein a thickness ratio of the first cementitious layer to the cementitious core layer to the second cementitious layer is in a range from 1:1:1 to 1:20:1, such as from 1:2:1 to 1:15:1, or from 1:3:1 to 1:10:1.

15 . A method of manufacturing a building board, comprising:
preparing a laminate comprising a polymer film attached by an adhesive layer to a first fiber mat, the laminate comprising a mat surface and a polymer surface; applying a cementitious slurry onto the mat surface of the laminate; applying a second mat onto the cementitious slurry; and drying the cementitious slurry to form a cementitious layer,
wherein the building board has a water absorption of not greater than 10% by weight after 2-hour immersion as per ASTM C 473-13, and wherein the cementitious slurry comprises a reactive water-insoluble polymer adapted for binding the first mat and the second mat to the cementitious layer.

16 . The method according to claim 15 , wherein applying the cementitious slurry comprises:
applying a first outer cementitious slurry comprising the reactive water-insoluble polymer to form a first cementitious layer; applying a core cementitious slurry being essentially free of the water-insoluble polymer to form a core cementitious layer; and applying a second outer cementitious slurry comprising the reactive water-insoluble polymer to form a second cementitious layer.

17 . The method according to claim 16 , wherein a thickness ratio of the first cementitious layer to the cementitious core layer to the second cementitious outer layer is in a range from 1:1:1 to 1:20:1, such as from 1:2:1 to 1:15:1, or from 1:3:1 to 1:10:1.

18 . The method according to claim 15 , wherein the reactive water-insoluble polymer is a self-crosslinking emulsion polymer.

19 . The method according to claim 15 , wherein the reactive water-insoluble polymer includes a vinyl acetate ethylene copolymer, a styrene acrylic copolymer, an acrylic copolymer, or any combination thereof.

20 . The method according to claim 15 , wherein the cementitious layer includes gypsum, Portland cement, magnesium oxide, magnesium phosphate, or any combination thereof.

Assignees

• Certainteed Gypsum Inc

Inventors

• Lai Choung-Houng
• Boydston Gerald
• Wiltzius Bryan
• Frailey Nathan
• Lemberger Michael J

Classifications

• B32B37/12

  characterised by using adhesives · CPC title

• B32B38/164

  Drying · CPC title

• B32B13/04

  comprising such {water setting} substance as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a glass layer B32B17/06)} · CPC title

• B32B7/12

  using interposed adhesives or interposed materials with bonding properties · CPC title

• B32B13/14

  next to a fibrous or filamentary layer · CPC title