Stable water-in-oil emulsions of cationically modified quaternized polyacrylamide and their method of preparation

An improved process for the stabilization of water-in-oil emulsions of cationically modified acrylamide polymers of the type prepared by reacting an acrylamide polymer with formaldehyde and a secondary amine containing 2-8 carbon atoms followed by quaternization with an alkylating agent, said water-in-oil emulsion comprising:

• A. 5-60% by weight finely divided cationically modified acrylamide polymer;
• B. 5-75% hydrophobic oil;
• C. 20-90% by weight water;
• and
• D. 0.1-21% by weight oil-in-water emulsifying agent;
• the improved process comprising:
• A. Preparing an aqueous solution of a water soluble phosphorous containing compound having a P-H bond, said solution having a pH of from 1.5-4.5;
• B. Adding the aqueous solution of step A to the water-in-oil emulsion with agitation in a quantity to simultaneously:
• 1. provide to the water-in-oil emulsion from 1.6-25% of the phosphorous containing compound based on the weight of the cationically modified acrylamide polymer present in the water-in-oil emulsion;
• and
• 2. adjust the pH of said water-in-oil emulsion to from 3.5-5.0;
• and then, in the absence of heating,
• C. Recovering a stabilized water-in-oil emulsion of the cationically modified acrylamide polymer, said water-in-oil emulsion being readily invertible when added to water in the presence of a hydrophilic surfactant, the polymer contained in the water-in-oil emulsion being stabilized against cross linking.