METHOD OF GRINDING ALKALI METAL BORATE GLASSES

摘要

1493739 Grinding glass DOW CHEMICAL CO 22 Dec 1975 [23 Dec 1974] 52357/75 Heading ClM Particles of a glass consisting of 90-98% by weight B 2 O 3 and 2-10% Na 2 O and/or K 2 O, the particles being of effective diameter at least 2 microns, are ground to a powder, at least some of which is of particles of diameter less than 1 micron, while contacting the particles with at least one aliphatic acyclic amine having up to 42 carbon atoms, at least one chain comprising 12 or more carbon atoms, at a temperature such that the vapour pressure of the amine is at least 1 mm. Hg but below both the transition temperature of the glass and the alteration temperature (defined) of the amine. The grinding may be at 50-300‹ C. for 7-10 days. 0À5-2À5%, based on the weight of glass, of amine may be used. The amine is preferably of formula where RSP1/SP is C 15-20 alkyl or alkenyl and RSP2/SP and RSP3/SP are each H, alkyl or alkenyl, the amine containing 15-24 carbon atoms (e.g. hexadecyl amine or dimethyl octadecyl amine). The amine may be used with a diluent, e.g. toluene, decalin, decane, xylene, kerosene, cumene, carbon tetrachloride, perfluorodecane or a tetrafluoroethylene telomer. A unitary glass body may be formed by: (i) mixing 40-60 parts by weight of the ground borate glass powder with 60-40 parts of a glass miscible with the borate glass on fusing, the said glass being of particle size (approx.) 45-75 Á, and adding 7-14 parts of non-aqueous liquid vehicle per 100 parts of glass mixture to form an extrudable paste; (ii) shaping the paste; (iii) heating to remove the vehicle; and (iv) fusing the remaining glasses. The miscible glass may have the same composition as the borate glass. The liquid vehicle may be cumene, toluene, xylene, cyclohexanone, nitrobenzene and dodecane. The unitary body may be a tube-sheet for a battery cell.