Continuous process for the preparation of a cationically modified acrylamide polymer

Claim 1

A method for the preparation of a dilute aqueous solution of a cationically modified polyacrylamide from a water-in-oil emulsion of a finely divided water soluble acrylamide polymer which comprises the steps of: A. forming a continuous process stream, said process stream containing water; B. adding to the continuous process stream at a first point a water soluble lower alkyl secondary amine containing 2-4 carbon atoms so as to prepare an aqueous process stream containing 1.0- 15.0% by weight of the secondary amine; C. adding to the continuous process stream at a second point downstream from said first point a water soluble surfactant so as to provide a concentration of the surfactant of from 0.1 to 2.0% by weight in the process stream, said surfactant being characterized as having the ability to invert a water-in-oil emulsion of a water soluble acrylamide polymer; D. adding to the continuous process stream at a third point downstream from said second point an aqueous solution of formaldehyde in a concentration sufficient to provide a mole ratio of formaldehyde to secondary amine within said process stream of from 1.1:0.9 to 0.9:1.1; E. adding to the continuous process stream at a fourth point downstream from said third point a quantity of a water-in-oil emulsion of a finely divided water soluble acrylamide polymer containing from 20- 50% polymer by weight in a quantity sufficient to give a mole ratio of amide functionality on said acrylamide polymer to formaldehyde of from 0.9:1 to 1.0:0.9; F. mixing continuously the process stream at a fifth point downstream from said fourth point, at a temperature of from 15°-50° C. so as to cause inversion of the water-in-oil emulsion of a finely divided acrylamide polymer and effect the reaction of the secondary amine, formaldehyde and acrylamide with each other; and then G. recovering continuously at a sixth point downstream from said fifth point a 3- 15% aqueous solution of a cationically modified acrylamide polymer.

Claim 2

A method for the preparation of a dilute aqueous solution of a cationically modified polyacrylamide from a water-in-oil emulsion of a finely divided water soluble acrylamide polymer which comprises the steps of: A. forming a continuous process stream, said process stream containing water; B. adding to the continuous process stream at a first point a water soluble lower alkyl secondary amine containing 2-4 carbon atoms so as to prepare an aqueous process stream containing 1.0- 15.0% by weight of the secondary amine; C. adding to the continuous process stream at a second point downstream from said first point a water soluble surfactant so as to provide a concentration of the surfactant of from 0.1 to 2.0% by weight in the process stream, said surfactant being characterized as having the ability to invert a water-in-oil emulsion of a water soluble acrylamide polymer; D. adding to the continuous process stream at a third point downstream from said second point an aqueous solution of formaldehyde in a concentration sufficient to provide a mole ratio of formaldehyde to secondary amine within said process stream of from 1.1:0.9 to 0.9:1.1; E. adding to the continuous process stream at a fourth point downstream from said third point a quantity of a water-in-oil emulsion of a finely divided water soluble acrylamide polymer containing from 20- 50% polymer by weight in a quantity sufficient to give a mole ratio of amide functionality on said acrylamide polymer to formaldehyde of from 0.9:1 to 1.0:0.9; F. mixing continuously the process stream at a fifth point downstream from said fourth point, at a temperature of from 15°-50° C. so as to cause inversion of the water-in-oil emulsion of a finely divided acrylamide polymer and effect the reaction of the secondary amine, formaldehyde and acrylamide with each other; and then G. recovering continuously at a sixth point downstream from said fifth point a 3- 15% aqueous solution of a cationically modified acrylamide polymer.