Gypsum-containing product, and composition, and method for producing a gypsum-containing product

Abstract

The invention provides a set gypsum-containing product having increased resistance to permanent deformation and a method for preparing it comprising forming a mixture of a calcium sulfate material, water, and an appropriate amount of one or more enhancing materials chosen from condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units. The mixture is then maintained under conditions sufficient for the calcium sulfate material to form a set gypsum material.

What is claimed is:  
     
         1 . A method for producing a set gypsum-containing product having increased resistance to permanent deformation, comprising: 
 forming a mixture of a calcium sulfate material, water, and one or more enhancing materials chosen from the group-consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and    maintaining the mixture under conditions sufficient for the calcium sulfate material to form a set gypsum material,    the enhancing material or materials having been included in the mixture in an amount such that the set gypsum formed has greater resistance to permanent deformation than it would have if the enhancing material had not been included in the mixture.    
     
     
         2 . The method of  claim 1 , wherein the concentration of the enhancing material in the mixture is from about 0.004 to about 2.0 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         3 . The method of  claim 1 , wherein the concentration of the enhancing material in the mixture is from about 0.04 to about 0.16 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         4 . The method of  claim 1 , wherein the concentration of the enhancing material in the mixture is about 0.08 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         5 . The method of  claim 1 , wherein the enhancing material comprises one or more of the following acids or salts, or the anionic portions thereof: sodium trimetaphosphate, sodium hexametaphosphate having 6-27 repeating phosphate units, tetrapotassium pyrophosphate, trisodium dipotassium tripolyphosphate, sodium tripolyphosphate, tetrasodium pyrophosphate, aluminum trimetaphosphate, sodium acid pyrophosphate, ammonium polyphosphate having 1000-3000 repeating phosphate units, or polyphosphoric acid having 2 or more repeating phosphoric acid units.  
     
     
         6 . The method of  claim 1 , wherein the mixture further comprises a pregelatinized starch.  
     
     
         7 . The method of  claim 1 , wherein the calcium sulfate material comprises one or more of: calcium sulfate anhydrite; calcium sulfate hemihydrate; calcium sulfate dihydrate; or ions of calcium and sulfate.  
     
     
         8 . The method of  claim 1 , wherein the calcium sulfate material comprises calcium sulfate hemihydrate.  
     
     
         9 . The method of  claim 8 , wherein the enhancing material comprises one or more of the following salts, or the anionic portions thereof: sodium trimetaphosphate, sodium hexametaphosphate having 6-27 repeating phosphate units, and ammonium polyphosphate having 1000-3000 repeating phosphate units.  
     
     
         10 . The method of  claim 1 , wherein the calcium sulfate material comprises calcium sulfate dihydrate.  
     
     
         11 . The method of  claim 10 , wherein, in addition to having greater resistance to permanent deformation, the set gypsum formed also has greater strength than it would have if the enhancing material had not been included in the mixture.  
     
     
         12 . The method of  claim 1 , wherein the mixture further comprises at least 0.015 weight percent (based on the weight of calcium sulfate material in the mixture) of chloride ions or salts thereof.  
     
     
         13 . The method of  claim 1 , wherein the mixture comprises 0.02-1.5 weight percent (based on the weight of calcium sulfate material in the mixture) of chloride ions or salts thereof.  
     
     
         14 . A set gypsum-containing product prepared by the method of  claim 10 .  
     
     
         15 . A set gypsum-containing product prepared by the method of  claim 12 .  
     
     
         16 . A gypsum board having increased sag resistance, comprising a core of material sandwiched between cover sheets, wherein the core comprises set gypsum, and the board has been prepared by a method comprising: 
 forming or depositing a mixture between the cover sheets, wherein the mixture comprises a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and    maintaining the mixture under conditions sufficient for the calcium sulfate material to form a set gypsum material,    the enhancing material or materials having been included in the mixture in an amount such that the gypsum board formed has greater sag resistance than it would have if the enhancing material had not been included in the mixture.    
     
     
         17 . The gypsum board of  claim 16 , wherein the concentration of the enhancing material in the mixture is from about 0.004 to about 2.0 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         18 . The gypsum board of  claim 16 , wherein the concentration of the enhancing material in the mixture is from about 0.04 to about 0.16 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         19 . The gypsum board of  claim 16 , wherein the concentration of the enhancing material in the mixture is about 0.08 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         20 . The gypsum board of  claim 16 , wherein the enhancing material comprises one or more of the following acids or salts, or the anionic portions thereof: sodium trimetaphosphate, sodium hexametaphosphate having 6-27 repeating phosphate units, tetrapotassium pyrophosphate, trisodium dipotassium tripolyphosphate, sodium tripolyphosphate, tetrasodium pyrophosphate, aluminum trimetaphosphate, sodium acid pyrophosphate, ammonium polyphosphate having 1000-3000 repeating phosphate units, or polyphosphoric acid having 2 or more repeating phosphoric acid units.  
     
     
         21 . The gypsum board of  claim 16 , wherein the calcium sulfate material comprises one or more of: calcium sulfate anhydrite; calcium sulfate hemihydrate; calcium sulfate dihydrate; or ions of calcium and sulfate.  
     
     
         22 . The gypsum board of  claim 16 , wherein the calcium sulfate material comprises calcium sulfate hemihydrate.  
     
     
         23 . The gypsum board of  claim 22 , wherein the enhancing material comprises one or more of the following salts, or the anionic portions thereof: sodium trimetaphosphate, sodium hexametaphosphate having 6-27 repeating phosphate units, and ammonium polyphosphate having 1000-3000 repeating phosphate units.  
     
     
         24 . The gypsum board of  claim 16 , wherein the calcium sulfate material comprises calcium sulfate dihydrate.  
     
     
         25 . The gypsum board of  claim 16 , wherein, in addition to having greater sag resistance, the gypsum board also has greater strength than it would have if the enhancing material had not been included in the mixture.  
     
     
         26 . The gypsum board of  claim 16 , wherein the mixture further comprises at least 0.015 weight percent (based on the weight of calcium sulfate material in the mixture) of chloride ions or salts thereof.  
     
     
         27 . The gypsum board of  claim 16 , wherein the mixture comprises 0.02-1.5 weight percent (based on the weight of calcium sulfate material in the mixture) of chloride ions or salts thereof.  
     
     
         28 . The gypsum board of  claim 26 , wherein the mixture further comprises a pregelatinized starch.  
     
     
         29 . The gypsum board of  claim 16 , wherein the mixture further comprises a pregelatinized starch.  
     
     
         30 . The gypsum board of  claim 29 , wherein the concentration of the pregelatinized starch in the mixture is from about 0.08 to about 0.5 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         31 . The gypsum board of  claim 29 , wherein the concentration of the pregelatinized starch in the mixture is from about 0.16 to about 0.4 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         32 . The gypsum board of  claim 29 , wherein the concentration of the pregelatinized starch in the mixture is about 0.3 percent by weight, based on the weight of the calcium sulfate material.  
     
     
         33 . The gypsum board of  claim 16 , wherein: the core has voids uniformly distributed therein; and the mixture further comprises an aqueous foam.  
     
     
         34 . The gypsum board of  claim 33 , wherein the aqueous foam has been formed from a foaming agent, or a blend of foaming agents, having the formula  
       CH 3 (CH 2 ) X CH 2 (OCH 2 CH 2 ) Y OSO 3 ⊖M⊕ 
       wherein X is a number from 2 to 20, Y is a number from 0 to 10 and is 0 in at least 50 weight percent of the foaming agent or blend of foaming agents, and M is a cation.  
     
     
         35 . The gypsum board of  claim 34 , wherein Y is 0 in from 86 to 99 weight percent of the foaming agent or blend of foaming agents.  
     
     
         36 . The gypsum board of  claim 16 , wherein the mixture further comprises a pregelatinized starch and an aqueous foam.  
     
     
         37 . A composite board comprising set gypsum and a reinforcing material, the board having been prepared by a method comprising: 
 forming or depositing a mixture on a surface, wherein the mixture comprises the reinforcing material, a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and    maintaining the mixture under conditions sufficient for the calcium sulfate material to form a set gypsum material,    the enhancing material or materials having been included in the mixture in an amount such that the set gypsum formed has greater resistance to permanent deformation than it would have if the enhancing material had not been included in the mixture.    
     
     
         38 . A composite board comprising set gypsum and host particles, at least a portion of the set gypsum being positioned in and about accessible voids in the host particles, the board having been prepared by a method comprising: 
 forming or depositing a mixture on a surface, wherein the mixture comprises: the host particles; calcium sulfate hemihydrate, at least a portion of which is in the form of crystals in and about the voids of the host particles; water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and    maintaining the mixture under conditions sufficient for the calcium sulfate hemihydrate to form set gypsum, whereby the portion of the set gypsum in and about the accessible voids in the host particles forms by in situ hydration of the calcium sulfate hemihydrate crystals in and about the voids of the host particles,    the enhancing material or materials having been included in the mixture in an amount such that the set gypsum formed has greater resistance to permanent deformation than it would have if the enhancing material had not been included in the mixture.    
     
     
         39 . A set gypsum-containing product employed to finish a joint between edges of gypsum boards, the product having been prepared by a method comprising: 
 inserting into the joint a mixture comprising a binder, a thickener, a non-leveling agent, a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and    maintaining the mixture under conditions sufficient for the calcium sulfate material to form a set gypsum material,    the enhancing material or materials having been included in the mixture in an amount such that the set gypsum formed has greater resistance to permanent deformation than it would have if the enhancing material had not been included in the mixture.    
     
     
         40 . A set gypsum-containing acoustical tile prepared by a method comprising: 
 forming or depositing in a tray a mixture comprising a gelatinized starch, a mineral wool, a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and    maintaining the mixture under conditions sufficient for the calcium sulfate material to form a set gypsum material,    the enhancing material or materials having been included in the mixture in an amount such that the set gypsum formed has greater resistance to permanent deformation than it would have if the enhancing material had not been included in the mixture.    
     
     
         41 . A set gypsum-containing acoustical tile prepared by a method comprising: 
 forming or depositing in a tray a mixture comprising a gelatinized starch, expanded perlite particles, a fiber reinforcing agent, a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and    maintaining the mixture under conditions sufficient for the calcium sulfate material to form a set gypsum material,    the enhancing material or materials having been included in the mixture in an amount such that the set gypsum formed has greater resistance to permanent deformation than it would have if the enhancing material had not been included in the mixture.    
     
     
         42 . A set gypsum-containing machinable product prepared by a method comprising: forming a mixture comprising a starch, particles of a water-redispersble polymer, a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units, and 
 maintaining the mixture under conditions sufficient for the calcium sulfate material to form a set gypsum material,    the enhancing material or materials having been included in the mixture in an amount such that the set gypsum formed has greater resistance to permanent deformation than it would have if the enhancing material had not been included in the mixture.    
     
     
         43 . A composition, useful for producing a gypsum board, comprising a mixture of: a calcium sulfate material, water, a pregelatinized starch and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units.  
     
     
         44 . A composition, useful for producing a gypsum board, comprising a mixture of: a calcium sulfate material, water, an aqueous foam, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units.  
     
     
         45 . The composition of  claim 44 , wherein the mixture further comprises a pregelatinized starch.  
     
     
         46 . A composition useful, when mixed with water, for producing a composite board comprising set gypsum and host particles, at least a portion of the set gypsum being positioned in and about accessible voids in the host particles, wherein the composition comprises a mixture of: the host particles having the accessible voids therein; calcium sulfate hemihydrate, at least a portion of which is in the form of crystals in and about the voids of the host particles; and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units.  
     
     
         47 . A composition useful, when mixed with water, for producing a machinable set gypsum-containing product, comprising a mixture of: a starch, particles of a water-redispersble polymer, calcium sulfate hemihydrate, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units  
     
     
         48 . A composition useful, when mixed with water, for finishing joints between edges of gypsum boards, comprising a mixture of: a binder, a thickener, a non-leveling agent, calcium sulfate hemihydrate, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units  
     
     
         49 . A composition, useful for producing an acoustical tile, comprising a mixture of: a gelatinized starch, a mineral wool, a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units.  
     
     
         50 . A composition, useful for producing an acoustical tile, comprising a mixture of: a gelatinized starch, expanded perlite particles, a fiber reinforcing agent, a calcium sulfate material, water, and one or more enhancing materials chosen from the group consisting of: condensed phosphoric acids, each of which comprises 2 or more phosphoric acid units; and salts or ions of condensed phosphates, each of which comprises 2 or more phosphate units.  
     
     
         51 . A method for producing a set gypsum-containing product having increased strength, rigidity, and dimensional stability, comprising: forming a mixture of calcined gypsum, water, and trimetaphosphate ion, and maintaining the mixture under conditions sufficient for the calcined gypsum to convert to set gypsum.