GB512875A - Improvements relating to glass fibres - Google Patents

Abstract

512,875. Glass manufacture; glass wool. CHANCE BROS. & CO., Ltd. (Maatschappij Tot Beheer en Exploitatie Van Octrooien N.V.). March 25, 1938, No. 9141. [Class 56] Fibres are made from a glass composed of silica, boric oxide, monobasic and dibasic oxides, the boric oxide content being at least 5 per cent. by weight and the monobasic oxide content being less than 12 per cent. The remaining constituents are present in sufficient quantity to give the glass a coefficient of linear expansion of at least 40 x 10<-7>. A suitable batch is composed of 2,000 parts by weight of sand, 180 parts of felspar, 500 parts of burned dolomite, 725 parts of rasorite (or equivalent borax), and 275 parts of soda ash. This produces a glass containing 63.73 per cent. of Si O2, 14.91 per cent. of Ca O and MgO, 9.97 per cent. of B2O3, 9.99 per cent. of Na2O, and 1.40 per cent. of other oxides. Other batches, and the composition of the resulting glasses, are given in the Specification. The B2O3 content is preferably at least 10 per cent. although it may vary from 5 to 25 per cent. The dibasic oxides may include lime, magnesia, barium oxide, zinc oxide, and iron oxide. Alumina may be added in any desirable amounts. The purpose of the invention is to produce fibres which are stable in use and are without any deleterions effect on surrounding substances, such as aluminium. A method of determining chemically the suitability of glass for the purpose of the invention is given in the description. Specification 428,720 is referred to.