GB790049A - Improvements in cation-exchange resins - Google Patents

Abstract

Cation-exchange resins consist of cross-linked phenol-aldehyde resins containing alkylene sulphonic groups and acetic acid groups. They are prepared by reacting mono-, di- or trichloracetic acid with a cross-linked phenolaldehyde resin containing phenolic hydroxy groups and alkylene sulphonic groups under alkaline conditions. The alkaline conditions are preferably produced by caustic alkali in excess. Other bases such as sodium carbonate, ammonia and pyridine may be used. Both the chloracetic acid and the sulphonic groups are preferably neutralized before the reaction, the latter groups being neutralized with metallic cations. The cross-linked resins may be prepared by condensing a phenol alkylene sulphonic acid, phenol and an aldehyde such as formaldehyde or a polymer thereof. Instead of a phenol alkylene sulphonic acid, the acids of catechol, hydroquinone or a cresol may be used; and hydroquinone, catechol, resorcinol, pyrogallol, tannins or m-hydroxy phenoxy acetic acid may be used instead of the phenol. Alternatively, the cross-linked resins may be made by condensing a phenol with formaldehyde and sodium bisulphite in aqueous solution. The resin is preferably ground to the desired size before treatment. The examples describe the preparation of ion-exchangers from monochloracetic and resins prepared from (1) phenol, formaldehyde and sodium bisulphite, (2) resorcinol methylene sulphonic acid, cross-linked with phenol; (3) phenol methylene sulphonic acid, cross-linked with quebrancho tannin; and (4) resorcinol methylene sulphonic acid, cross-linked with m-hydroxyphenoxyacetic acid and phenol. Specifications 588,380, [Group IV], and 613,139 are referred to.