A method for preparing organo - silica aerogels

摘要

An oleaginous liquid, for example a hydrocarbon lubricating oil, may be thickened by dispersing in it from 0.2% to 1.5% for example of an organo-silica aerogel comprising a silicon polymer having siloxy groups and containing from 0.4% to 1.2% by weight carbon, 0.9 to 1.5% by weight hydrogen, and having an SiO2 to carbon atom ratio of from 10:1 to 50:1 and an SiO2 to hydrogen atom ratio of from 0.77:1 to 2:1, the average particle size being in the range of from 1.0 to 2.5 microns. Examples relate to an SAE No. 10 motor oil containing 0.5% aerogel and an SAE No. 20 motor oil containing 0.3% aerogel.ALSO:An amorphous organo-silica aerogel comprises a silica polymer having siloxy groups and containing carbon and hydrogen atoms chemically bound to a portion of the siloxy groups in the aerogel, the aerogel having an SiO2 to carbon atom ratio of from 10 : 1 to 50 : 1 and a SiO2 to hydrogen atom ratio of from 0.77 : 1 to 2 : 1. The aerogels may have total surface area of from 100 to 400 square metres per gram, external surface area of from 1.75 to 1.95 square metres per gram, and average particle size of from 1.0 to 2.5 microns. The starting materials are organo-silica aerogels prepared by known methods from silica hydro-organo sols having a pH of from 1-8 to 4.5 and containing from 8 to 20 mols. per mol. of SiO2 of a neutral, water-miscible organic liquid, for example an alcohol or ketone. A first group of aerogels according to the invention are prepared by heating the starting aerogels at a temperature in the range 90 DEG to 375 DEG C., preferably in an atmosphere of superheated steam. A second group of aerogels according to the invention are prepared either from aerogels of the first group or from the starting materials by heating at a temperature in the range of 350 DEG to 750 DEG C., preferably in air at atmospheric or superatmospheric pressure.ALSO:0.2 to 5.0% by weight (based on the composition) of an organo-silica aerogel may be used to thicken liquids comprising solutions or suspensions of nitrocellulose, cellulose acetate, chlorinated rubber, polyvinylacetate, polyvinylchloride, polyacrylic esters, cellulose butyrate, cellulose propionate; plastisols comprising halogenated vinyl or vinylidene resins; polymerizable liquids comprising unsaturated alkyd resins, esters of monohydric alcohols and polycarboxylic acids, alkyl esters of acrylic or methacrylic acids alone or with vinyl monomers. The aerogel has an SiO2 to carbon atom ratio of from 10: 1 to 50: 1 and an SiO2 to hydrogen atom ratio of from 0.77: 1 to 2: 1, and is prepared by the method described in Division C1. Examples relate to compositions comprising one of polyvinyl chloride, nitrocellulose, cellulose acetate with the aerogel, ethyl acetate and castor oil, the nitrocellulose and cellulose acetate compositions including ethanol and ethanol/toluol respectively; polyvinyl chloride, dioctyl phthalate, lead phosphite and the aerogel; an unsaturated polyester resin prepared from phthalic anhydride, maleic anhydride and propylene glycol, with the aerogel; glyceryl tris-cyclohexyl maleate, dioctyl phthalate and one or more of tertiary butyl perbenzoate, vinyl acetate-chloride copolymer, decarboxylated castor oil, butyl methacrylate, and the aerogel.