| 摘要 |
<p>1,136,016. Silica sols. MONSANTO CHEMICALS Ltd. 28 March, 1967 [21 April, 1966], No. 17567/66. Heading C1A. [Also in Division C7] A sol contains from 1 to 30% by weight of the total composition of collidal silica in a dispersion medium comprising a monohydric alcohol having from 1 to 3 carbon atoms per molecule, up to 10% by weight of the alcohol of water and from 0À1 to 10% by weight of the total composition of hydrochloric acid (expressed as 100% HC1) or from 0À1 to 15% by weight of the total composition of sulphuric acid (expressed as 100% H 2 SO 4 ). The novel colloidal dispersions of silica that are of most value in practice contain from 4 to 30% by weight of silica, and not more than 5% by weight of HC1 or H 2 SO 4 , and preferably from 0À25 to 5% by weight of the alcohol of water Compositions described in examples 1 to 9 are claimed per se. The silica sols are produced by passing an electric current through a liquid medium comprising the above composition using a silicon anode in contact with the liquid medium. The alcohol is preferably ethanol or methanol and the anode is substantially pure silicon or ferrosilicon containing from 60 to 99% by weight of silicon. The process is most conveniently carried out under reflux at the normal boiling point of the liquid medium, and preferably includes a preliminary period of "anode activation" during which an electric current is passed through the liquid medium with the electrode that is to serve as the anode in the production of the silica sol as the cathode.</p> |
