Highly uniform, porous element prodn. - from aq. dispersion of binder-coated, crushable fibres

摘要

Porous element is made by (a) forming a homogeneous dispersion of crushable brittle fibres of dia. 0.001-10 mu in an aq. medium; (b) raising the pH to >=7; (c) adding a colloidal soln. of an inorganic bonding agent; (d) lowering the pH to ppte. bonding agent onto the fibres; (e) forming a mat of interlaced fibres by deposition from the dispersion; (f) compressing the mat to break at least some fibres and form a mat of uniform density; and (g) drying. Prefd. fibres are alumina fibres of dia. 1-5 mu. Bonding agents is pref. an alumina (boehmite) sol added in an amt. to provide 15-35% solids on fibre w/w. As filters or as liq., gas or vapour dispensers, partic. in aerating units for e.g. sewage treatment; in gas-cooling devices in synthetic fibre prodn; as wick elements in chromatography. Elements have high degree of porosity uniformity.