| 摘要 |
PURPOSE:To obtain a dispersant enhanced in dispersing capacity, by fractionating a naphthalenesulfonic acid/formalin condensate with a high condensation degree by using an ultrafiltration membrane to collect a low-molecular fraction. CONSTITUTION:Either one of (a) a naphthalenesulfonic acid/formalin condensate and (b) a condensate of alkyl substituted nephthalenic acid or an aromatic compound based thereon and formalin both of which have a high condensation degree of a mixture of two kinds or more is fractionated by using an ultrafiltration membrane with a fractionation MW of 30,000 or more, pref., 20,000 or more to collect a low-molecular fraction with a MW of 30,000 or less. That is, because the amount of the unreacted monomer and dinuclear - trinuclear substances in the solid component of the naphthalenesulfonic acid/formalin condensate are reduced, an effective component increases and dispersing capacity is enhanced. Furthermore, as compared with a conventional naphthalenesulfonic acid/formalin condensate starting from crude naphthalene, because anti-staining property is improved and an inexpensive stock material can be used, the improvement in a stock material is enabled.
|
