Preparation of stable film forming aqueous polyamide dispersions

Claim 1

THE PROCESS FRO PREPARING A FILM-FORMING AQUEOUS POLYMER DISPERSION COMPRISING: (A) COMPLETELY DISSOLVING 15-25% BY WEIGHT OF (1) A POLYAMIDE OF A DIAMINE AND A DICARBOXYLIC ACID, AND (2) AS A MODIFIER, A PHENOL, AROMATIC ALCOHOL OR AROMATIC GLYCOL WHICH AT LEAST SWELLS SAID POLYAMIDE, OR AN EPOXY COMPOUND HYDROLYZABLE TO SUCH MODIFIER, THE AMOUNT OF SAID MODIFIER OR EPOXY COMPOUND BEING SUCH AS TO PROVIDE 2030% MODIFIER BASED ON THE WEIGHT OF SAID POLYAMIDE AND SAID MODIFIER, IN 75-85% BY WEIGHT OF AN ALIPHATIC ALCOHOL-BASED SOLVENT SYSTEM WHICH IS SUBSTANTIALLY WATER-IMMISCIBLE, (B) EMULSIFYING THE RESULTING SOLUTION IN WATER, THEN (C) ADDING TO AND MILLING TOGETHER WITH THE RESULTING EMULSION AN AQUEOUS SOLUTION CONTAINING ABOUT 10% BY WEIGHT OF A COMPLETELY DISSOLVED POLYVINYL ALCOHOL HAVING A PERCENT HYDROLYSIS OF 78-90%, AND A 4% WATER SOLUTION VISCOSITY OF 20-45 CENTIPOISE AS DETERMINED AT 20*C. Y HOEPPLER FALING BALL METHOD, THE AMOUNT OF SAID AQUEOUS SOLUTION BEING SUFFICIENT TO SUPPLY 5-15% OF SAID POLYVINYL ALCOHOL BASED ON THE TOTAL WEIGHT OF SAID POLYAMIDE AND SAID MODIFIER, AND THEREAFTER, (D) GRADUALLY EVAPORATING AT LEAST 98 WEIGHT PERCENT OF SAID ALCOHOL-BASED SOLVENT SYSTEM FROM THE EMULSION OVER A TIME PERIOD OF 3-8 HOURS.