Canadian Patents & Development Ltd.

Marinos Xanthos

Raymond T Woodhams

Molding compounds in various forms for molding into high performance composites, are prepared from reinforcing mica platelets, preferably of high aspect ratio, and thermosetting unsaturated polyester resins. The unsaturated polyester solid and a solid vinylic monomer are blended, finely divided (e.g. to about -200 mesh), and the platelets are uniformly coated with these fine particles by dry blending. A compaction with partial coalescence of the fine resin particles in situ is carried out to densify and aggregate the coated platelets and shape the mixture. The resulting molding powders, bulk or sheet molding compounds are readily molded into the high performance composites, the platelets being substantially protected from degradation by the distributed resin.

Preparing mica-reinforced composites

Chrysotile asbestos is chemically opened into the individual fibrils by soluble vinylic polymer polyelectrolytes containing carboxylic acid groups in aqueous media. Polyacrylic acids, polymethacrylic acids, maleic anhydride polymers and water-soluble copolymers thereof are preferred polyelectrolytes and form stable colloidal dispersions. The polyelectrolytes are neutralized to alkaline pH with inorganic or organic bases, but preferably with basic vinylic monomers when complete encapsulation is desired. By a further aspect of the invention the polyelectrolyte-coated fibrils in aqueous dispersion are encapsulated by copolymerization with (a) a basic vinylic comonomer (used for pH control) such as dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate or a vinylpyridine; and (b) a non-basic vinylic comonomer such as styrene, divinylbenzene, vinyl chloride or fluoride, vinyl acetate, methyl methacrylate, ethyl acrylate, acrylonitrile, and methacrylonitrile. The encapsulated fibrils are advantageous for forming reinforced composites including laminates and foamed or cellular products.

Growing community of inventors

Toronto, Canada

Marinos Xanthos