Dow Corning Corporation

Bryan Thomas

Thomas Easton

Julie Joseph

A method for the preparation of a hydrophobic clay by contacting an aqueous suspension of the clay with an organosilane of formula R.sup.1.sub.a SiX.sub.4-a or an organosiloxane comprising units of formula R.sup.2.sub.n SiO.sub.(4-n)/2 in the presence of an acid and a water-miscible solvent. The resulting clay suspension is then contacted with a water-immiscible solvent to effect separation of the hydrophobed clay from the suspension.

Method for preparing hydrophobic clay

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.

Gypsum mixture containing hydrophobic additive and method for

A method for preparing an aqueous gypsum mixture having hydrophobic additive substantially uniformly dispersed therein, which method comprises admixing in water gypsum, a silane of the general formula (RO).sub.3 SiR' or the general formula (RO).sub.2 SiRR' and non-emulsified polysiloxane of the general formula; ##STR1## wherein each R is the same or different and represents a hydrocarbon group having from one to eight carbon atoms, R' represents a lower alkyl group which is optionally substituted by an amino, amino-loweralkylene-amino or dialkylenetriamine group, and a has an average value of between 20 and 200. The silane is preferably N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and the polysiloxane preferably trimethyl end-blocked linear methylhydrogen polysiloxane. The method may further include adding surfactant. Also disclosed is a gypsum product which includes gypsum mixture prepared according to the above method.

Method for hydrophobing gypsum

The specification describes and claims a method for the de-emulsification of emulsions of water and crude oil which comprises treating the emulsion with an organosiloxane, a siloxane unit having a quaternary ammonium group R'N.sup.+ (R.sup.2).sub.3 X.sup.- linked to its silicon atom, R' represents a divalent hydrocarbon group linking the silicon and nitrogen atoms, each R.sup.2 represents an alkyl group having up to 20 carbon atoms or a polyoxyalkylene chain having 3 to 50 oxyalkylene groups, and X.sup.- represents a halogen ion. Examples of organosiloxanes given include those composed exclusively of the said units, and copolymers composed of these siloxane units and siloxane units according to the general formula R.sub.b (SiO.sub.4-b)/2 in which each R is a substituted or unsubstituted hydrocarbon group of up to 10 carbon atoms, and b has the value 0. 1, 2 or 3, for example those according to the average general formula

De-emulsification of oils

A method of de-hazing distillate fuel is disclosed which comprises adding to the fuel a solution of a halide salt dissolved in an alcohol, and an alcohol soluble organosiloxane. The halide salt may be the chloride of magnesium, cadmium, copper, nickel or the tetra methyl ammonium group, for example the salt may have the formula MgCl.sub.2.6H.sub.2 O or (CH.sub.3).sub.4 NCl. The organosiloxane may be a cyclic, linear or branched material and may have e.g. a minor amount of siloxane units having the general formula ##EQU1## and a minor amount of siloxane units having the general formula ##EQU2## in which each R represents a substituted or unsubstituted hydrocarbon group of up to ten carbon atoms, a has the value 0, 1, 2, or 3, b has the value 0, 1 or 2, c has the value 1 or 2, and each Z represents a group linked to the silicon atom and comprising a functional organic group. Each group Z may be a group selected from the polyoxyalkylene group R'(OCH.sub.2 CH.sub.2).sub.p (OCH.sub.2 CH.CH.sub.3).sub.r OR', the amine group R'NHQ, the quaternary ammonium salt R'NR.sub.3.sup.2 X, the carboxylate group R'CO.sub.2 M, the sulphonate group R'SO.sub.3 M, or the hydroxyl group, in which R' represents a group which provides a link to the silicon atom through an oxygen or a carbon atom, p has a value in the range 1 to 100, r has a value in the range 0 to 50, the sum of p and q is in the range 2 to 100, R' represents a hydrogen atom, an alkyl group or an acyl group, Q represents a hydrogen atom or a group R'NHQ, each R.sup.2 represents an alkyl group, X represents a halide ion and each group M represents a cation.

Removal of water haze from distillate fuel

The specification discloses a method of de-hazing distillate fuel which comprises adding to the fuel an organosiloxane having at least one quaternary ammonium substituted siloxane unit having the general formula

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Barry, United Kingdom

Bryan Thomas