Continuous formation of cationically modified polyacrylamide aq. soln. - by inverting water-oil emulsion of polyacrylamide into aq. phase in which it reacts with sec. amine and formaldehyde

摘要

A dil. aq. soln. of a cationically modified polyacrylamide is prepd. from a W/O emulsion (I) of finely divided water soluble acrylamide polymer by (A) forming a continuous process stream contg. (a) 1-15 wt. % of a water-soluble alkyl sec. amine contg. 2-4C, (b) 0.5-40 wt. % of HCHO introduced as a 1-40 wt. % aq. soln., the amt. being equimolar to the sec. amine, (c) 1.4-9 wt. % of the emulsion (I), (d) 0.1-2 wt. % of a water-soluble hydrophilic surfactant capable of inverting the emulsion (I), and (e) water; (B) subjecting the process stream to turbulent in-line mixing whereby the emulsion (I) is inverted and reaction between the HCHO, the sec. amine and the polymer is effected; and (C) recovering continuously a 1.0-15% aq. soln. of the modified polymer. (I) comprises (i) 30-95 wt. % of a polymer-contg. aq. phase, (ii) 5-70 wt. % of a hydrophobic liq. oil phase and (iii) 0.1-21 wt. % based on the emulsion of a W/O emulsifying agent. The aq. phase contains 20-50 wt. % of finely divided acrylamide polymer, based on the aq. phase. The process does not require the step of first preparing a premix, and makes use of a high polymer content, yet very stable W/O emulsion. The soln. is storage stable for several weeks. The soln. is useful in the area of paper retention and the dewatering of industrial and municipal wastes.