A process for preparing aqueous solutions of low molecular weight polyacrylic acids with reproducible molecular weight

摘要

Prepn. is claimed of aq. of polyacrylic acids, copolymers of these substances or their corresp. salts using polymerisation catalysts formed by NH4, Na or K salts of persulphuric acid, H2O2 and organic peroxides or by oxidn.-redn. pairs of the preceding substances with Na metalisulphite, Na bisulphite and ascorbic acid, in an aq. medium and open atmos. - The improvement is the gradual and programme addition of the monomers and catalysts to a certain initial amt. of water kept at 5-15 deg.C, the reaction medium being heated for 4-5 hrs., to temps. not lower than 70 deg.C and, after cooling, neutralising the reaction prod. with an alkali hydroxide.