PURPOSE: To obtain a dispersant enhanced in dispersing property, by subjecting a naphthalenesulfonic acid/formalin condensate with a high condensation degree to ultrafiltration to collect a high-molecular fraction.
CONSTITUTION: A condensate of naphthalenesulfonic acid or alkyl group substituted naphthalenesulfonic acid and formalin or a polycondensate of naphthalenesulfonic acid or alkyl group substituted naphthalenesulfonic acid, lignosulfonic acid and formaldehyde having a high condensation degree is fractionated by an ultrafiltration membrane with a fractionation MW of 10,000 or more, pref., 20,000 or more to collect a high-molecular fraction. That is, by the treatment of the ultrafiltration membrane, residual monomer and oligomer low in dispersing capacity and high in air entrainment property are removed and the amount of an inorg. substance such as Glauber's salt not relating to dispersing capacity is reduced while the amount of the effective component in a solid is increased and dispersing property is enhanced. As a result, the addition amount of a dispersant necessary for obtaining the same slump value is reduced.
SUGIWAKI TOSHIHIRO
INADA OSAMU
NAKAMOTO TOMOFUMI
| JPS58124529A | 1983-07-25 |