Gypsum boards with glass fiber reinforcements having a titanate or zirconate coupling coating

Abstract

A bond is created between a gypsum matrix and titanium or zirconium based coupling coating applied onto a glass fiber during gypsum board cure. The commercially available titanium or zirconium based coupling has a generic formula of the type [RO-}-nTi—[—OXR′Y]4-n or [RO-}-nZr—[—OXR′Y]4-n. These coupling compositions chemically bond to glass fibers by replacing the —OH groups present on the glass fibers in aqueous solutions with Ti—O or Zr—O bonds. In order to bond with calcium ions in hydrated gypsum crystals, the X functionality is selected to be a phosphate or pyrophosphato group. The bond between the glass fiber and the titanium or zirconium based coupling composition is due to the formation of a monolayer, while the bond between the hydrated gypsum crystal and the coupling composition is intermittent due the acicular structure of gypsum crystals. The titanium or zirconium based coupling composition coating on glass fibers bonded to the gypsum matrix results in load transfer between the gypsum matrix and the glass fibers, resulting in improved flexure strength and nail pullout resistance. The Titanate/Zirconate can also be used as a board mechanical properties enhancing agent without addition of glass fiber.

1 . A gypsum board, comprising: 
 a. a gypsum matrix formed from an aqueous gypsum slurry and having a bottom and a top, said gypsum matrix being operable to form hydrated gypsum crystals having calcium ions when said gypsum board is cured;    b. a first facer sheet placed on said bottom of said gypsum matrix;    c. a second facer sheet placed on said top of said gypsum matrix;    d. one or more glass fibers placed within said gypsum matrix, said glass fibers having external surfaces and having OH ions thereon;    e. said glass fibers coated with a coupling composition of the type [RO-}-nTi—[—OXR′Y]4-n] or [RO-}-nZr—[—OXR′Y]4-n], said coupling composition type being operable to form Ti—O or Zr—O bonds when bonding chemically to said glass fibers and having X functionality, said X functionality being a phosphate or pyrophosphate group; and    f. said coupling composition bonding chemically to said glass fibers by replacing said OH ions with said Ti—O or Zr—O bonds, said coupling composition forming a coupling composition coating on said external surfaces of said glass fibers, said X functionality of said coupling composition forming a bond with said calcium ions of said hydrated gypsum crystals during said gypsum board cure,    said coupling composition coating providing increased strength, flexure resistance and nail pull out resistance to said gypsum board.    
   
   
       2 . A gypsum board as recited by  claim 1 , wherein each of said first and said second facer sheets comprises Kraft paper.  
   
   
       3 . A gypsum board as recited by  claim 1 , wherein said gypsum matrix comprises calcium sulphate hemihydrate (CaSO 4 ½H 2 O), calcium sulphate anhydrite (CaSO 4 ), hydraulic setting cement and water.  
   
   
       4 . A gypsum board as recited by  claim 3 , wherein said hydraulic setting cement is selected from the group consisting of Portland cements, sulphate resisting cements, blast furnace cements, pozzolanic cements, and high alumina cements  
   
   
       5 . A gypsum board as recited by  claim 1 , wherein said coupling composition coating has a thickness of a few monolayers on said glass fibers said external surfaces.  
   
   
       6 . A gypsum board as recited by  claim 1 , wherein said coupling composition comprises LICA 12 Titanium IV 2,2 [bis 2-propenolatomethyl]butanolato, tris [dioctyl]phosphate-O.  
   
   
       7 . A gypsum board as recited by  claim 1 , wherein said coupling composition comprises LICA 38 Titanium IV 2,2 [bis 2-propenolatomethyl]butanolato, tris[dioctyl]pyrophosphato-O.  
   
   
       8 . A gypsum board as recited by  claim 1 , wherein said coupling composition comprises LICA 38 ENP Titanium IV 2,2 [bis 2-propenolatomethyl]butanolato, tris[dioctyl]pyrophosphato-O:Ethoxylated nonyl phenony-1:1.  
   
   
       9 . A gypsum board as recited by  claim 1 , wherein said coupling composition comprises LICA 38J Titanium IV [bis-2-propenolato-methyl]-1-butanolato, bis(dioctyl)pyrophosphato-O,{adduct} 3 moles N,N-dimethylamino-alkyl propenoamide.  
   
   
       10 . A gypsum board as recited by  claim 1 , wherein said coupling composition comprises NZ 38 Zirconium IV 2,2[bis-2-propenolato methyl]butanolato, tris(dioctyl)pyrophosphate-O.  
   
   
       11 . A gypsum board as recited by  claim 1 , wherein said coupling composition comprises NZ 38J Zirconium IV 2,2-dimethyl 1,3 propanediolato, bis [dioctyl]pyrophosphato-O [addduct] 2moles N,N-dimethylamino-alkyl proenoamide.  
   
   
       12 . A gypsum board as recited by  claim 1 , wherein said coupling composition in the said aqueous gypsum slurry is 0.01 to 3 weight percent of said glass fibers incorporated in said gypsum matrix.  
   
   
       13 . A gypsum board as recited by  claim 1 , wherein said glass fibers are randomly arranged.  
   
   
       14 . A gypsum board as recited by  claim 1 , wherein said glass fibers are arranged in the form of organized structures such as mats.  
   
   
       15 . A method of coating glass fibers with a titanium or zirconium based coupling composition, comprising: 
 a. dissolving a coupling composition in an aqueous solution;    b. immersing glass fibers within said aqueous solution;    c. agitating said aqueous solution to promote a uniform coating of said glass fibers forming a monolayer of a titanium or zirconium based coupling coating;    d. filtering said aqueous solution to recover said fibers having a titanium or zirconium based coupling coating;    e. forming a mat and/or other organized structure from said glass fibers having a titanium or zirconmium based coupling coating, said mat and/or other organized structure operable for insertion into a gypsum slurry.    f. Coat fiber through roller coating under the bushing    
   
   
       16 . A process for manufacture of gypsum board, comprising the steps of: 
 a. dissolving a coupling composition in an aqueous solution;    b. roller coating of glass fibers with said aqueous solution;    c. uniform coating of said glass fibers with a few monolayer of titanium or zirconium based coupling composition coating.    d. adding coated glass fibers to an aqueous gypsum slurry comprising calcium sulphate hemihydrate with additives including starch, binder, accelerator, retarder, superplasticizer, water resistant agent, foaming agents, biocides etc;    e. casting said gypsum slurry with said glass fibers having said monolayer of said titanium or zirconium based coupling composition coating on a first facer sheet, said gypsum casting having a top and a bottom;    f. applying a second facer sheet placed on said top of said gypsum casting and forming a gypsum board; and    g. drying and curing said gypsum board,    said gypsum board being operative to increase strength, flexure resistance and nail pull out resistance.