Gypsum mixture containing hydrophobic additive and method for hydrophobing gysum
AssigneeDow Corning Corporation
InventorBryan Thomas
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Abstract
A gypsum mixture is disclosed which has hydrophobic additive substantially uniformly dispersed therein and which comprises gypsum, a first silane of the general formula (RO).sub.3 SiR or of the general formula (RO).sub.2 SiR.sub.2, and a second silane of the general formula (RO).sub.3 SiR' or of the general formula (RO).sub.2 SiRR', wherein each R is the same or different and represents a lower alkyl group, and R' represents a lower alkyl group which is substituted by a substituent selected from an amino, amino-lower alkyl-amino or dialkylenetriamine group. Preferably, the first silane is methyltrimethoxysilane and the second silane is N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. Also disclosed is a method for preparing said gypsum mixture.
Claims16
A gypsum mixture having hydrophobic additive substantially uniformly dispersed therein, said hydrophobic additive consisting essentially of a first silane selected from the group consisting of silanes of the general formula (RO).sub.3 SiR and of the general formula (RO).sub.2 SiR.sub.2, and a second silane selected from the group consisting of silanes of the general formula (RO).sub.3 SiR' and of the general formula (RO).sub.2 SiRR', wherein each R independently represents a lower alkyl group and R' represents a lower alkyl group which is substituted by a substituent selected from the group consisting of amino, amino-lower alkyl amino and dialkylenetriamine groups.
A method for preparing an aqueous gypsum mixture having hydrophobic additive substantially uniformly dispersed therein, which method comprises mixing in water, gypsum, a hydrophobic additive consisting essentially of a first silane selected from the group consisting of silanes of the general formula (RO).sub.3 SiR and of the general formula (RO).sub.2 SiR.sub.2, and a second silane selected from the group consisting of silanes of the general formula (RO).sub.3 SiR' and of the general formula (RO).sub.2 SiRR', wherein each R independently represents a lower alkyl group, and R' represents a lower alkyl group which is substituted by a substituent selected from the group consisting of an amino, amino-lower alkyl-amino and dialkylenetriamine group.
Dependencies are inferred from the claim text.