| 摘要 |
1279250 Silica xerogel UNILEVER Ltd 22 Oct 1969 [28 Oct 1968] 51110/68 Heading C1A [Also in Division C6] A silica xerogel having a surface area of between 700 and 1200 square metres per gram, a pore volume at least 0À7 c.c./g. and a mean pore diameter from 25 to 80 Š based on a wide distribution of pore sizes and of average particle size less than 20 microns, at least 10% by weight of the particles being smaller than 10 or 5 microns, is used for the reduction of haze in beer. The xerogels may be prepared, as a continuous process, by reacting together under high shear an alkali metal silicate and sulphuric acid. The silica produced is washed with sulphuric acid to yield a hydrogel, and the hydrogel is dried and comminuted to give the xerogel. Several washing techniques are disclosed. The hydrogel may be spray-dried or dried in a rotary or oven drier, and hammer milled or air micronized. |
