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EP-4735402-A1 - ALKALI METAL POLYBORATE SILICATE COATING FOR ACOUSTICAL PANEL AND GYPSUM BOARD

EP4735402A1EP 4735402 A1EP4735402 A1EP 4735402A1EP-4735402-A1

Abstract

A coating composition for improving the sag resistance of a gypsum panel or a fibrous panel, the composition including 25 to 100 wt. % alkali metal polyborate silicate inorganic binder, based on the total weight of the dry coating. The inorganic binder includes alkali metal polyborate silicate resulting from combining alkali metal polyborate and alkali metal silicate. Further provided are fibrous panels having a backing side and an opposing facing side including a coating of the inorganic binder, and methods of preparing same. Further provided are gypsum panels having a backing side and an opposing facing side including a coating of the inorganic binder, and methods of preparing same.

Inventors

  • GUO, DONG
  • LI, QINGHUA

Assignees

  • USG Interiors, LLC

Dates

Publication Date
20260506
Application Date
20240614

Claims (10)

  1. 1. A coated building panel comprising a building panel selected from a fibrous panel or a gypsum wallboard, the building panel comprising a backing side and an opposing facing side and having a cured coating layer disposed on at least one side of the building panel; the fibrous panel comprising the backing side and the opposing facing side; the gypsum wallboard having a gypsum core and the backing side comprising a back fibrous cover sheet and the opposed facing side comprising a front fibrous cover sheet, wherein the gypsum core is between the front fibrous cover sheet and the back fibrous cover sheet; the cured coating layer comprising about 25 to 100 wt. %, preferably 30-100 wt. %, more preferably 30-80 wt. %, alkali metal polyborate silicate inorganic binder, based on the total dry weight of the cured coating.
  2. 2. The coated building panel of claim 1, further comprising an intermediate coating layer comprising 25 -100 wt % on a dry basis alkali metal silicate directly disposed on the at least one side of the building panel having the cured coating layer to be between the panel and the cured coating layer.
  3. 3. The coated building panel of claim 1, wherein the cured coating layer is directly disposed on the at least one side of the building panel having the cured coating layer.
  4. 4. The coated building panel of claim 1, wherein the alkali metal polyborate silicate inorganic binder of the cured coating composition comprises a mixture of alkali metal polyborate and alkali metal silicate, wherein the alkali metal polyborate is 5 to 50%, typically 10 to 50 wt.%, more typically 10-30 wt.%, of the total of the alkali metal polyborate and the alkali metal silicate.
  5. 5. The coated building panel of claim 1, wherein the alkali metal polyborate silicate binder results from a mixture of an alkali metal polyborate and an alkali metal silicate dissolved in water.
  6. 6. The coated building panel of any of claims 1, 4 or 5, wherein the alkali metal polyborate comprises a reaction product of a boric acid compound and an alkali metal borate in water, wherein the inorganic binder is less than 5 wt.% borate other than said polyborate and less than 5 wt.% boric acid.
  7. 7. The coated building panel of claim 5, wherein the mixture of the alkali metal polyborate and the alkali metal silicate dissolved in water is transparent.
  8. 8. The coated building panel of any of claims 1, 4 or 5, wherein the alkali metal silicate is selected from the group consisting of sodium silicate, potassium silicate, lithium silicate and combinations thereof.
  9. 9. The coated building panel of claim 1, wherein the inorganic binder comprises sodium silicate and the alkali metal polyborate, wherein the alkali metal polyborate comprises a final reaction product of a boric acid compound and sodium tetraborate.
  10. 10. A method of making the coated building panel of any of claims 1 to 9, comprising: providing the building panel comprising a backing side and an opposing facing side, and depositing a first coating layer of an aqueous coating composition comprising an inorganic alkali metal polyborate silicate binder dissolved in water on at least one side of the building panel selected from the backing side and the opposing facing side, the inorganic alkali metal polyborate silicate binder comprising a mixture of an inorganic alkali metal polyborate and an inorganic alkali metal silicate, curing the coating layer of the aqueous coating composition comprising the inorganic alkali metal polyborate silicate binder to form a cured coating layer comprising the inorganic alkali metal polyborate silicate binder; the cured coating layer comprising about 25 to 100 wt. %, preferably 30-100 wt. %, more preferably 30-80 wt. %, alkali metal polyborate silicate inorganic binder, based on the total dry weight of the cured coating.

Description

ALKALI METAL POLYBORATE SILICATE COATING FOR ACOUSTICAL PANEL AND GYPSUM BOARD FIELD OF THE INVENTION [0001] The disclosure relates generally to a building panel, such as a fibrous panel (acoustical panel) or a gypsum board, coated with a coating composition comprising a cured binder comprising alkali metal polyborate silicate, and methods of making same. More particularly, the alkali metal polyborate silicate results from curing a mixture of an inorganic alkali metal polyborate and an inorganic alkali metal silicate dissolved in water. Typically the mixture of the inorganic alkali metal polyborate and the inorganic alkali metal silicate dissolved in water is a transparent solution. Optionally the alkali metal polyborate silicate binder is applied to the building panel as suspension of inert filler particles suspended in the aqueous solution of alkali metal polyborate and alkali metal silicate. BACKGROUND OF THE INVENTION [0002] Acoustical panels (or tiles) are specially designed systems that are intended to improve acoustics by absorbing sound and/or reducing sound transmission in an indoor space, such as a room, hallway, conference hall, or the like. Although there are numerous types of acoustical panels, a common variety of acoustical panel is generally composed of mineral wool fibers, fillers, colorants and a binder, as disclosed, for example, in U.S. Pat. No. 1,769,519. These materials, in addition to a variety of others, can be employed to provide acoustical panels with desirable acoustical properties and other properties, such as color and appearance. [0003] In order to prepare acoustical panels, fibers, fillers, bulking agents, binders, water, surfactants and other additives are typically combined to form a slurry and processed. Cellulosic fibers are typically in the form of recycled newsprint. The bulking agent is typically expanded perlite. Fillers may include clay, calcium carbonate or calcium sulfate. Binders may include starch, latex and reconstituted paper products linked together to create a binding system that facilitates locking all ingredients into a desired structural matrix. [0004] Organic binders, such as starch, are often the primary binder component providing structural adhesion for the panel. Starch is a preferred organic binder because, among other reasons, it is relatively inexpensive. For example, panels containing newsprint, mineral wool and perlite can be bound together economically with the aid of starch. Starch imparts both strength and durability to the panel structure, but is susceptible to problems caused by moisture. Moisture can cause the panel to soften and sag, which is unsightly in a ceiling and can lead to the weakening of the panel. [0005] One method used to counter problems caused by moisture in panels is to provide a method of coating a fibrous panel comprising providing a fibrous panel comprising a backing side and an opposing facing side, and depositing a first coating layer on at least one side of the fibrous panel, the first coating layer comprising an inorganic binder, wherein the inorganic binder is present in an amount between about 10 and 100 wt. %, based on the total weight of the dry first coating layer, the inorganic binder comprises a borate salt and a metal silicate selected from the group consisting of an alkali metal silicate, an alkaline earth metal silicate, and combinations thereof, and the inorganic binder is water soluble as disclosed in published patent application no. US 2019/0382589 Al to Li et al. [0006] US 2019/0382589 Al to Li et al. also provides a curable coating composition for improving the sag resistance of a fibrous panel, the curable coating composition comprising about 10 to 100 wt. % inorganic binder, based on the total weight of a dry coating formed therefrom, wherein the inorganic binder comprises a borate salt and a metal silicate selected from the group consisting of an alkali metal silicate, an alkaline earth metal silicate and combinations thereof, and the inorganic binder is water soluble. A disadvantage of US 2019/0382589 Al to Li et al. is that if the borate salt concentration is raised too much then the composition is not transparent at room temperature (about 20°C) due to precipitation of the boron-continuing compound. [0007] Products made of gypsum (calcium sulfate dihydrate; CaSO4»2H2 O) are generally manufactured by combining stucco, also known as calcined gypsum (calcium sulfate hemihydrate; CaSCh’UPLO), with water and other ingredients as desired (such as foaming agent and other additives). Gypsum can be naturally found or synthetically developed and then calcined to make the stucco. The stucco, water, and other additives are normally combined in a mixer, at a “wet end” of a manufacturing line. The resulting slurry is set into a desired shape of a product, such as gypsum board (sometimes called “drywall”). It is the rehydration reaction of the slurry with water that forms set gypsum. Board is sometimes referred t