# US 11,702,373 B2 · Gypsum wallboard with enhanced fire resistance, and related coatings and methods

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- Number: US 11,702,373 B2
- Document ID: US11702373B2
- Status: Granted
- Kind: B2
- Application number: 16/804,936
- Filed: 2020-02-28
- Published: 2020-12-17
- Granted: 2023-07-18
- Earliest claimed: 2019-06-17
- Assignees: United States Gypsum Company
- Applicants: United States Gypsum Company
- Inventors: Qinghua Li; Naser Aldabaibeh; Mark Hemphill; Trevor Rische; Suman Sinha Ray
- Web page: https://patentgrep.com/patent/US11702373B2

## CPC

- C04B 41/5024: {Silicates (C04B41/5022 takes precedence; silico-fluorides C04B41/5018)}
- B28B 11/04: for coating {or applying engobing layers}(glazing, engobing C04B)
- B28B 11/14: for dividing shaped articles by cutting
- B28B 11/243: {Setting, e.g. drying, dehydrating or firing ceramic articles (B28B11/242 takes precedence)}
- B28B 19/0092: {to webs, sheets or the like, e.g. of paper, cardboard}
- B32B 13/08: of paper or cardboard
- C04B 28/14: containing calcium sulfate cements {(gypsum-paper plates E04C)}
- C04B 28/26: Silicates of the alkali metals
- C04B 30/00: Compositions for artificial stone, not containing binders
- C04B 41/009: {characterised by the material treated}
- C04B 41/4535: {applied as a solution, emulsion, dispersion or suspension}
- C04B 41/5089: {Silica sols, alkyl, ammonium or alkali metal silicate cements}
- C04B 41/68: Silicic acid; Silicates
- C09D 1/02: alkali metal silicates
- C09D 5/18: Fireproof paints {including high temperature resistant paints}
- E04B 1/942: {slab-shaped}
- E04C 2/043: {of plaster (E04C2/049 takes precedence)}
- B32B 2255/12: on paper layer
- B32B 2255/20: Inorganic coating
- B32B 2419/00: Buildings or parts thereof
- C04B 18/08: Flue dust {, i.e. fly ash}
- C04B 2111/00094: {Sag-resistant materials}
- C04B 2111/00482: {Coating or impregnation materials}
- C04B 2111/0062: {Gypsum-paper board like materials}
- C04B 2111/00629: {the covering sheets being made of material other than paper}
- C04B 2111/28: Fire resistance, i.e. materials resistant to accidental fires or high temperatures
- C04B 2111/34: Non-shrinking or non-cracking materials
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- B28B: SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER (foundry moulding B22C; working stone or stone-like material B28D; shaping of substances in a plastic state, in general B29C; making layered products not composed wholly of these substances B32B)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- E04B: GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS (border constructions of opening in walls, floors or ceilings E06B1/00; {electromagnetic shielding H05K9/0001})
- E04C: STRUCTURAL ELEMENTS; BUILDING MATERIALS (for bridges E01D; specially designed for insulation or other protection E04B; elements used as building aids E04G; for mining E21; for tunnels E21D; structural elements with broader range of application than for building engineering F16, particularly F16S)

## Abstract

Disclosed are an organic binder-based coating; a composite gypsum board containing face and back cover sheets, an outside surface of the back cover sheet bearing the coating; and a method of preparing composite board where the back cover sheet contains the coating on its outer surface. The coating is formed from a composition comprising an alkaline silicate, a solid filler, and optionally, a borate. An enhancing layer can also be applied to the back cover sheet.

## Claims

### Claim 1

A gypsum board comprising:
a gypsum layer disposed between a face and back cover sheet, the gypsum layer comprising set gypsum;
a coating disposed on an outer surface of the back cover sheet, the coating formed from a composition comprising an alkaline silicate, a solid filler, and optionally a borate;
an enhancing layer disposed, directly or indirectly, on the outer surface of the back cover sheet, the enhancing layer formed from a composition comprising a mild acidic material in aqueous solution and a second solid filler additive, the mild acid material containing calcium chloride, aluminum sulfate, phosphoric acid, aluminum chloride, magnesium chloride, acetic acid, or any combination thereof and the second solid filler additive containing mica, clay, wollastonite, magnesite, perlite, talc, bentonite, limestone, gypsum, zinc oxide, zinc sulfate, hollow beads, zeolites, fly ash, bottom ash, coal ash, steel slag, iron slag, limestone slag, or any combination thereof, wherein the coating and the enhancing layer are in either order relative to the gypsum layer;
the gypsum board having a High Temperature Shrinkage (S) of about 10% or less in the z direction when heated to about 1560° F. (850° C.), according to ASTM C1795-15 when the board is tested at a thickness of ⅝ (0.625) inch.

### Claim 2 (depends on 1)

The gypsum board of claim 1, wherein the alkaline silicate is a sodium silicate, a potassium silicate, a lithium silicate, or any combination thereof.

### Claim 3 (depends on 1)

The gypsum board of claim 1, wherein the alkaline silicate is a sodium silicate.

### Claim 4 (depends on 1)

The gypsum board of claim 1, wherein the solid filler is mica, clay, wollastonite, magnesite, perlite, talc, bentonite, limestone, gypsum, zinc oxide, zinc sulfate, hollow beads, zeolites, fly ash, bottom ash, coal ash, steel slag, iron slag, limestone slag, or any combination thereof.

### Claim 5 (depends on 1)

The gypsum board of claim 1, wherein the borate is present and is sodium metaborate, sodium tetraborate, potassium tetraborate, potassium pentaborate, ammonium pentaborate, borax decahydrate, boric oxide, or any combination thereof.

### Claim 6 (depends on 1)

The gypsum board of claim 1, wherein the gypsum layer is formed from a slurry comprising high expansion particles in an amount of up to about 10% by weight of stucco, said particles having a volume expansion of about 300% or more of their original volume after being heated for about one hour at about 1560° F. (850° C.).

### Claim 7 (depends on 6)

The gypsum board of claim 6, the slurry further comprising expandable graphite.

### Claim 8 (depends on 1)

The gypsum board of claim 1, the board having a High Temperature Shrinkage (S) of about 10% or less in the x-y directions (width-length) when heated to about 1560° F. (850° C.) according to ASTM C1795-15 when the board is tested at a thickness of ⅝ (0.625) inch.

### Claim 9 (depends on 1)

The gypsum board of claim 1, the board having a Thermal Insulation Index (TI) of about 20 minutes or greater according to ASTM C1795-15 when the board is tested at a thickness of ⅝ (0.625) inch.

### Claim 10 (depends on 1)

The gypsum board of claim 1, where, when the board is cast at a nominal thickness of ⅝-inch, an assembly is constructed in accordance with any one of UL Design Numbers U305, U419 or U423, the assembly having a first side with a single layer of gypsum boards and a second side with a single layer of gypsum boards, and surfaces of gypsum boards on the first side of the assembly are heated in accordance with the time-temperature curve of ASTM E119-09a, while surfaces of gypsum boards on the second side of the assembly are provided with temperature sensors pursuant to ASTM E119-09a, the gypsum boards inhibit the transmission of heat through the assembly such that: a maximum single value of the temperature sensors is less than about 325° F. plus ambient temperature after about 60 minutes; or an average value of the temperature sensors is less than about 250° F. plus ambient temperature after about 60 minutes.

### Claim 11

A gypsum board comprising:
a gypsum layer disposed between a face and back cover sheet, the gypsum layer comprising set gypsum;
a coating disposed on an outer surface of the back cover sheet, the coating formed from a composition comprising an alkaline silicate, a solid filler, and optionally a borate;
the gypsum board having a High Temperature Shrinkage (S) of about 10% or less in the x-y directions (width-length) when heated to about 1560° F. (850° C.) according to ASTM C1795-15 when the board is tested at a thickness of ⅝ (0.625) inch.

### Claim 12 (depends on 11)

The board of claim 11, wherein:
the alkaline silicate is a sodium silicate;
the solid filler is mica, clay, wollastonite, magnesite, perlite, talc, bentonite, limestone, gypsum, zinc oxide, zinc sulfate, hollow beads, zeolites, fly ash, bottom ash, coal ash, steel slag, iron slag, limestone slag, or any combination thereof; and
the borate is present and is sodium metaborate, sodium tetraborate, potassium tetraborate, potassium pentaborate, ammonium pentaborate, borax decahydrate, boric oxide, or any combination thereof.

### Claim 13 (depends on 12)

The board of claim 12, wherein the board has at least one of the following when the board is tested at a thickness of ⅝ (0.625) inch:
a High Temperature Shrinkage (S) of about 10% or less in the z direction when heated to about 1560° F. (850° C.), according to ASTM C1795-15;
a Thermal Insulation Index (TI) of about 20 minutes or greater according to ASTM C1795-15; and/or
where, when the board is cast at a nominal thickness of ⅝-inch, an assembly is constructed in accordance with any one of UL Design Numbers U305, U419 or U423, the assembly having a first side with a single layer of gypsum boards and a second side with a single layer of gypsum boards, and surfaces of gypsum boards on the first side of the assembly are heated in accordance with the time-temperature curve of ASTM E119-09a, while surfaces of gypsum boards on the second side of the assembly are provided with temperature sensors pursuant to ASTM E119-09a, the gypsum boards inhibit the transmission of heat through the assembly such that: a maximum single value of the temperature sensors is less than about 325° F. plus ambient temperature after about 60 minutes; or an average value of the temperature sensors is less than about 250° F. plus ambient temperature after about 60 minutes.

### Claim 14

A method of making gypsum board comprising:
(a) mixing at least water and stucco to form a slurry;
(b) disposing the slurry between a face cover sheet and a back cover sheet to form a board precursor;
(c) cutting the board precursor into a board;
(d) drying the board; and
(e) applying a coating composition on an outer surface of the back cover sheet, the coating composition comprising an alkaline silicate, a solid filler, and optionally a borate;
(f) applying an enhancing layer directly or indirectly on the outer surface of the back cover sheet, the enhancing layer formed from a composition comprising a mild acidic material in aqueous solution and a second solid filler additive, the mild acid material containing calcium chloride, aluminum sulfate, phosphoric acid, aluminum chloride, magnesium chloride, acetic acid, or any combination thereof; and the second solid filler additive containing mica, clay, wollastonite, magnesite, perlite, talc, bentonite, limestone, gypsum, zinc oxide, zinc sulfate, hollow beads, zeolites, fly ash, bottom ash, coal ash, steel slag, iron slag, limestone slag, or any combination thereof, wherein the coating and the enhancing layer are in either order relative to the gypsum layer;
wherein the gypsum board has at least one of the following when the board is tested at a thickness of ⅝ (0.625) inch:
a High Temperature Shrinkage (S) of about 10% or less in the z direction when heated to about 1560° F. (850° C.), according to ASTM C1795-15;
a High Temperature Shrinkage (S) of about 10% or less in the x-y directions (width-length) when heated to about 1560° F. (850° C.) according to ASTM C1795-15;
a Thermal Insulation Index (TI) of about 20 minutes or greater according to ASTM C1795-15;
a High Temperature Thickness Expansion in the z direction of at least about 0.1% when thickness is evaluated according to the analogous techniques and methodology of ASTM C1795-15; and/or
where, when the board is cast at a nominal thickness of ⅝-inch, an assembly is constructed in accordance with any one of UL Design Numbers U305, U419 or U423, the assembly having a first side with a single layer of gypsum boards and a second side with a single layer of gypsum boards, and surfaces of gypsum boards on the first side of the assembly are heated in accordance with the time-temperature curve of ASTM E119-09a, while surfaces of gypsum boards on the second side of the assembly are provided with temperature sensors pursuant to ASTM E119-09a, the gypsum boards inhibit the transmission of heat through the assembly such that: a maximum single value of the temperature sensors is less than about 325° F. plus ambient temperature after about 60 minutes; or an average value of the temperature sensors is less than about 250° F. plus ambient temperature after about 60 minutes.

### Claim 15 (depends on 14)

The method of claim 14, wherein the alkaline silicate is a sodium silicate.

### Claim 16 (depends on 14)

The method of claim 14, wherein the solid filler is mica, clay, wollastonite, magnesite, perlite, talc, bentonite, limestone, gypsum, zinc oxide, zinc sulfate, hollow beads, zeolites, fly ash, bottom ash, coal ash, steel slag, iron slag, limestone slag, or any combination thereof.

### Claim 17 (depends on 14)

The method of claim 14, wherein the borate is present and is sodium metaborate, sodium tetraborate, potassium tetraborate, potassium pentaborate, ammonium pentaborate, borax decahydrate, boric oxide, or any combination thereof.

### Claim 18 (depends on 14)

The method of claim 14, wherein the coating is applied after the board is dried.