Polymer electrolyte filter aids

摘要

The polymers containing acid amide groups are dissolved in formaldehyde (or formaldehyde producing compound) aqueous solution, and a water-soluble salt of H2SO3 added so that the pH of the mixture is 9-13, and the temperature is 40-70 degrees C, 20-50% of the acid amide groups are converted to sulphomethyl groups and up to 15% to methylol groups. The product is condensed at higher temperatures by reaction of the methylol groups. The electrolytes may be used as filter aids, especially for the filtration of slimy OH precipitates, or as suspension stabilisers.