Glass reinforced gypsum board and method of manufacture

• US 20020187296A1
• Filed: 06/04/2002
• Published: 12/12/2002
• Est. Priority Date: 06/06/2001
• Status: Active Grant

• Current Assignee: Bpb Placo (Compagnie De Saint-Gobain)
• Original Assignee: Bpb Placo (Compagnie De Saint-Gobain)
• Inventors: Sanders, Christopher J., Hauber, Robert J., Hennis, Mark E., Fahey, Michael P.
• Granted Patent: US 6,866,492 B2
• Time in Patent Office: Days
• US Class Current: 428/68
• CPC Class Codes: B28B 11/0845 for smoothing
• CPC Class Codes: B28B 19/0092 to webs, sheets or the like, e.g. of paper, cardboard
• CPC Class Codes: B32B 13/02 with fibres or particles being present as additives in the layer
• 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 2607/00 Walls, panels
• CPC Class Codes: E04C 2/043 of plaster E04C2/049 takes precedence
• CPC Class Codes: Y10T 156/1011 Overedge bending or overedge folding
• CPC Class Codes: Y10T 156/1034 Overedge bending of lamina about edges of sheetlike base
• CPC Class Codes: Y10T 156/1043 Subsequent to assembly
• CPC Class Codes: Y10T 428/22 Nonparticulate element embedded or inlaid in substrate and visible
• CPC Class Codes: Y10T 428/23 Sheet including cover or casing
• CPC Class Codes: Y10T 428/232 Encased layer derived from inorganic settable ingredient
• CPC Class Codes: Y10T 428/237 Noninterengaged fibered material encased [e.g., mat, batt, etc.]
• CPC Class Codes: Y10T 428/239 Complete cover or casing

Abstract

A method of manufacture of multilayer gypsum board, and a multilayer gypsum board, having face sheets comprising randomly oriented inorganic or glass fibers completely impregnated with a gypsum slurry penetrating through the random interstices between the inorganic fibers and coating the board surfaces with gypsum slurry. Wet gypsum board passes through a board forming station having upper and lower forming plates, set at an angle relative to each other and being separated by a predetermined dimension substantially equal to the desired thickness of the manufactured gypsum board product. Additives in the gypsum, such as engineered polymers, provide for a better surface for coating. The gypsum board has a first layer of a mixture of set gypsum having an outer surface and the polymeric compound additive entrained therein and impregnated in a thin sheet of randomly aligned inorganic fibers to essentially encase the core gypsum within two facing layers. An edger bar assembly includes bases mounted on pneumatic arms at opposite lateral ends supporting an edger bar extending therebetween, and each base includes an attached flapper edge mechanism having an inboard surface abutting the gypsum board edge to retain unset slurry skimmed off the wet gypsum board surface by the edger bar from overflowing onto the conveyor belt. A microporous fluid bed mounted longitudinally across the board injects a fluid film under pressure by means of micropores into the interface between the bed surface and the top surface of the gypsum board to provide an ultrasmooth board surface.

Claims

1. A method of manufacture of gypsum board having inorganic fiber face sheets, comprising the steps of:

providing a first gypsum slurry having a first consistency;

applying a predetermined amount of said first gypsum slurry onto at least a first continuous sheet, said sheet including randomly aligned, inorganic fibers having random interstices between said fibers;

passing said first continuous inorganic fiber sheet through a gypsum application station, said station including at least one applicator wheel for passing the inorganic fiber sheet therethrough, so as to cause the first gypsum slurry having a first consistency to penetrate through said random interstices between the inorganic fibers and to thereby coat both top and bottom surfaces of said first inorganic fiber sheet with said gypsum slurry having a first consistency;

depositing a second gypsum slurry having a second consistency on said first inorganic fiber sheet and causing said second gypsum slurry to be essentially evenly distributed over an upwardly facing top surface of said first inorganic fiber sheet;

applying a third gypsum slurry having a third consistency to a second of said at least one continuous, inorganic, fiber sheets, said second inorganic fiber sheet having random interstices between the fibers and causing said third gypsum slurry to penetate essentially completely through said random interstices and to thereby coat both top and bottom surfaces of said second inorganic fiber sheet with said third gypsum slurry;

applying said second inorganic fiber sheet onto the second gypsum slurry thereby sheathing said second gypsum slurry within said first and second inorganic fiber sheets to form a wet gypsum board product;

forming said gypsum board product by passing said wet gypsum board through a first board forming station having a lower forming plate and an upper forming plate, said upper forming plate having at least a portion thereof being set at a predetermined angle to said lower forming plate, the separation between said lower forming plate and said portion of said upper forming plate defining a predetermined dimension substantially equal to the desired thickness of the manufactured gypsum board product; and

providing a second board forming station having a lower forming plate and a second upper forming plate, at least a portion of said second upper forming plate having a plurality of micropore conduits connected through a manifold to a source of pressurized water and terminating at the board contact surface of the second upper forming plate in a plurality of microporous apertures, wherein during operation, the microporous apertures provide a film of water over the top surface of the gypsum board product, which in conjunction with the force exerted by the board contact surface of said second upper forming plate on said board surface, produces a very smooth surface thereon.

2. The method of manufacture of gypsum board according to claim 1 wherein said step of providing said first gypsum slurry further comprises providing said first gypsum slurry having a slurry consistency which is substantially denser relative to said second gypsum slurry consistency.

3. The method of manufacture of gypsum board according to claim 1 wherein said step of applying said third gypsum slurry further comprises applying a third gypsum slurry having a third gypsum slurry consistency which is substantially identical to said first gypsum slurry consistency.

4. The method of manufacture of gypsum board according to claim 1, wherein said inorganic fiber of said lower and upper sheets further comprises a glass fiber.

5. The method of manufacture of gypsum board according to claim 1 further comprising passing the wet gypsum board through an edger bar assembly, so as to form the lateral edges of said gypsum board product and to complete the smoothing of the upper surface of said gypsum board product.

6. The method of manufacture of gypsum board according to claim 1 further comprising, after the second board forming step, an acrylic application step including applying an acrylic coating over the gypsum slurry containing said polymer layer on said gypsum board surface before said polymer is cured.

7. The method of manufacture of gypsum board according to claim 6 wherein said acrylic coating is applied by flood coating.

8. The method of manufacture of gypsum board according to claim 1 wherein the film of water applied over the top surface of the gypsum board product further comprises a continuous film.

9. In a gypsum board forming device comprising a supply of continuous sheet of inorganic fiber having random interstices between the fibers comprising said sheet, a gypsum slurry mixer including a gypsum delivery mechanism, at least one gypsum penetration station for penetrating said gypsum slurry into said random interstices between the inorganic fibers, a gypsum core delivery mechanism, a sheet joining mechanism for joining said continuous sheet of inorganic fiber to said core gypsum, and a gypsum conveyor line, having a belt with a surface, for conveying formed gypsum board from the sheet joining mechanism, and a gypsum forming station assembly comprising:

a) two laterally disposed edger shoes at least one laterally disposed edger bar clamping element attached to said edger shoes;

b) at least one laterally extending forming plate, having two ends, extending over a top surface of the formed gypsum board and between said edger bar clamping elements so that the forming plate rides over and smoothes said gypsum board top surface, at least a portion of said upper forming plate having a plurality of micropore conduits connected to a source of pressurized water and terminating at the board contact surface of the upper forming plate in a plurality of microporous apertures,

wherein during operation, the microporous apertures provide a film of water over the top surface of the gypsum board product, which in conjunction with the force exerted by the board contact surface of said upper forming plate on said board surface, produces a very smooth front face surface thereon.

10. A gypsum forming station assembly according to claim 9 wherein said source of pressurized water is connected to said a plurality of micropore conduits through a manifold.

11. A gypsum forming station assembly according to claim 9 wherein said source of pressurized water provides a continuous film of water over the surface of the top surface of the gypsum board product.

12. A gypsum forming station assembly according to claim 9 wherein said pressurized water in said source includes chemical additives.