Use of pre-coated mat for preparing gypsum board

• US 20050202742A1
• Filed: 03/12/2004
• Published: 09/15/2005
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: Georgia-Pacific Gypsum LLC
• Original Assignee: Georgia-Pacific Gypsum LLC
• Inventors: Smith, Russell, Randall, Brian
• Granted Patent: US 7,745,357 B2
• Time in Patent Office: Days
• US Class Current: 442/256
• CPC Class Codes: B28B 19/0092 to webs, sheets or the like, e.g. of paper, cardboard
• CPC Class Codes: B28B 23/0006 the reinforcement consisting of aligned, non-metal reinforcing elements
• CPC Class Codes: B32B 13/14 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 17/02 in the form of fibres or filaments
• CPC Class Codes: B32B 2260/021 Fibrous or filamentary layer layers of natural mineral fibres or particles being impregnated in a plastic substance B32B19/02
• CPC Class Codes: B32B 2260/044 Water-setting substance, e.g. concrete, plaster
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2419/00 Buildings or parts thereof walls, panels B32B2607/00
• CPC Class Codes: C03C 25/1095 to obtain coated fabrics
• CPC Class Codes: D06N 2205/023 Emulsion, aqueous dispersion, latex
• CPC Class Codes: D06N 2209/142 Hydrophobic
• CPC Class Codes: D06N 2209/1678 Resistive to light or to UV
• CPC Class Codes: D06N 3/0022 Glass fibres
• CPC Class Codes: D06N 3/0063 Inorganic compounding ingredients, e.g. metals, carbon fibres, Na2CO3, metal layers; Post-treatment with inorganic compounds
• CPC Class Codes: D06N 3/042 Acrylic polymers D06N3/045 takes precedence
• CPC Class Codes: E04C 2/043 of plaster E04C2/049 takes precedence
• CPC Class Codes: Y10T 428/24992 Density or compression of components
• CPC Class Codes: Y10T 428/249921 Web or sheet containing structurally defined element or component
• CPC Class Codes: Y10T 428/249932 Fiber embedded in a layer derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 442/2008 : Fabric composed of a fiber or strand which is of specific structural definition
• CPC Class Codes: Y10T 442/2066 : Different coatings or impregnations on opposite faces of the fabric
• CPC Class Codes: Y10T 442/2992 : Coated or impregnated glass fiber fabric
• CPC Class Codes: Y10T 442/361 : At least one layer is derived from water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 442/3797 : Coating or impregnation is derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 442/623 : Microfiber is glass
• CPC Class Codes: Y10T 442/645 : Parallel strand or fiber material is inorganic [e.g., rock wool, mineral wool, etc.]
• CPC Class Codes: Y10T 442/665 : Including a layer derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 442/699 : Including particulate material other than strand or fiber material

Abstract

A gypsum board which comprises a set gypsum core sandwiched between and faced with fibrous mats, wherein a free surface of one of said mats is pre-coated with a combination of a mineral pigment, optionally an inorganic adhesive binder and an organic binder, preferably a hydrophobic, UV resistant polymer latex adhesive binder applied to said surface as an aqueous coating composition, said aqueous coating composition upon drying and setting providing a pre-coated mat satisfying certain morphology requirements.

Claims

1. A fiber mat faced gypsum board made by

(1) contacting a gypsum slurry for forming a set gypsum core with

(2) a non-coated side of a pre-coated fiber mat, wherein the fiber mat has a thickness of between 0.02 and 0.045 inch and has a coating on a side opposite the non-coated side, said coating comprising a combination of (i) a mineral pigment, (ii) an organic binder and optionally (iii) an inorganic binder, the coating extending from a surface of said side opposite into said fiber mat a distance between about 30 and 50 percent of said thickness and having a microporosity which allows air to flow through and water to evaporate through said pre-coated mat from the gypsum core during preparation of the board,

(3) wherein the contacting causes said gypsum slurry to penetrate into the non-coated side and through interstices of the fiber mat to fill said interstices with gypsum and form a bond between said gypsum and said coating, and

(4) allowing the gypsum slurry to harden to form said set gypsum core, wherein the set gypsum core in a region near the bond has at least 17 percent combined water.

2. The board of claim 1 wherein the organic binder is a hydrophobic, UV resistant polymer latex.

3. The board of claim 2 wherein said mat contains glass fibers nominally about 10 to 16 microns in diameter.

4. The board of claim 3 in which said mat, in the absence of said coating, has a basis weight of 1 to 3 pounds per 100 square feet.

5. The board of claim 1 having a gypsum core density of 40 to 55 pounds per cubic foot.

6. The board of claim 1 wherein the coating weighs about 30 to 100 pounds per 1000 square feet of mat.

7. The board of claim 6 wherein the mineral pigment comprises from about 75 to 99 weight percent of the coating, the inorganic binder comprises from about 0 to 20 weight percent of the coating and the organic binder comprises from about 1 to 17 weight percent of the coating.

8. The board of claim 7 wherein the organic binder is a hydrophobic, UV resistant polymer latex.

9. The board of claim 8 wherein the mineral pigment comprises from about 83 to 95 weight percent of the coating, the inorganic binder comprises from about 0 to 10 weight percent of the coating and the hydrophobic, UV resistant polymer latex binder comprises from about 1 to 12 weight percent of the coating.

10. The board of claim 9 wherein said coating was applied to a surface of the fiber mat as an aqueous coating composition and dried to form said pre-coated mat.

11. The board of claim 10 wherein said aqueous coating composition includes about 0.1 to about 5 wt. % of one or more additives selected from the group consisting of a thickener, dispersant, colorant, defoaming agent and preservator.

12. The board of claim 11 in which said fiber mat, in the absence of said coating, has a basis weight of 1 to 3 pounds per 100 square feet.

13. The board of claim 10 wherein the amount of said water-resistant additive is at least about 0.2 wt. %.

14. The board of claim 13 wherein the amount of said water-resistant additive is about 0.3 to about 10 wt. %.

15. The board of claim 14 wherein said additive is selected from the group consisting of a wax emulsion, a wax-asphalt emulsion, poly(vinyl alcohol), a polysiloxane, a siliconate and mixtures thereof.

16. The board of claim 8 wherein the hydrophobic, UV resistant polymer latex adhesive binder consists essentially of a (meth)acrylic or (meth)acrylate polymer or a (meth)acrylic or (meth)acrylate copolymer.

17. The board of claim 16 wherein said one of the fibrous mats consists essentially of glass fibers and the other fibrous mat consists essentially of a blend of glass fibers and synthetic fibers.

18. The gypsum board of claim 2 wherein the mineral pigment comprises from about 75 to 99 weight percent of the coating, the inorganic adhesive binder comprises from about 0 to 20 weight percent of the coating and the hydrophobic, UV resistant polymer latex adhesive binder comprises from about 1 to 17 weight percent of the coating.

19. The gypsum board of claim 18 wherein the mineral pigment comprises from about 83 to 95 weight percent of the coating, the inorganic adhesive binder comprises from about 0 to 10 weight percent of the coating and the hydrophobic, UV resistant polymer latex adhesive binder comprises from about 1 to 12 weight percent of the coating.

20. The gypsum board of claim 18, or 19 wherein the hydrophobic, UV resistant polymer latex adhesive binder of said combination consists essentially of a (meth)acrylic or (meth)acrylate polymer or a (meth)acrylic or (meth)acrylate copolymer.