Process for the preparation of clay mineral-containing gels with stabilized structure and reversible water absorption ability

Claim 1

A process for the preparation of clay mineral-containing non-thixotropic gels with stabilized structure and reversible water absorption ability, characterized in that (a) the resistance of medium of an aqueous suspension sample containing a thixotropic, activated, swelling clay mineral of three-layer structure and/or swelling chain silicate is measured, thereafter in a series of tests a water soluble polymer capable of reacting with the clay mineral and/or chain silicate is added to the suspension samples either as such or in an aqueous solution, the resistance of medium of the resulting mixtures is measured, and the clay mineral:polymer:water ratios are determined at which the resistance of medium of the suspension is at least ten times higher than that of the initial, polymer-free suspension, whereby the useful limits are obtained, then (b 1 ) the clay mineral and/or chain silicate is contacted with the polymer in a ratio falling within the useful limits, in the presence of an amount of water within the useful limits, or (b 2 ) the clay mineral and/or chain silicate is contacted with the polymer in a ratio within or outside the useful limits, in the presence of more water than that corresponding to the useful limits, the water content of the resulting flocculate is then decreased mechanically to fall within the useful limits, and, if necessary, the clay mineral:polymer ratio of the mass is adjusted simultaneously within the useful limits by adding further amount(s) of clay mineral or chain silicate and/or polymer to the mass, and, if desired, the resulting gel is partially or totally dried, whereafter, if desired, the partially or totally dried gel is reacted in an aqueous medium with a polymer capable of reacting with the clay mineral or chain silicate under keeping the clay mineral:polymer ratio still within the useful limits.