Abstract: The present invention provides a highly water-pressure-resistant and highly moisture-permeable waterproof sheet comprising a fabric and a wet coagulated polyurethane film thereon, a organophilic clay complex prepared by introducing a quaternary ammonium ion into the interlayers of a expandable phillosilicate being dispersed into the wet coagulated polyurethane film in an amount of 0.5 to 20% by weight based on the solid component of the polyurethane, and the waterproof sheet having a water pressure resistance of at least 5,000 mm and a moisture permeability of at least 8,000 g/m.sup.2.24 hr. The waterproof sheet is prepared by a process comprising dissolving a polyurethane in a solvent containing mainly a nitrogen-containing polar solvent, dispersing a organophilic clay complex which is prepared by introducing a quaternary ammonium ion into the interlayers of a expandable phillosilicate into the polyurethane-containing solution in an amount of 0.

Abstract: There are disclosed an organophilic clay which comprises a hydroxypolyoxyethylenealkyl ammonium ion represented by the following formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 may be the same or different, and each represent a (CH.sub.2 CH.sub.2 O).sub.n H group (where n is 2 or more, preferably 2 to 20), a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, provided that one to three of R.sub.1 to R.sub.4 is/are a (CH.sub.2 CH.sub.2 O).sub.n H group(s) and at least three of R.sub.1 to R.sub.4 are (CH.sub.2 CH.sub.2 O).sub.n H group(s) and alkyl group(s),being introduced in interlayers of an expandable layer silicate, a method for preparing the same and a gellant for a high polar organic solvent.