Aqueous polyurethane coating emulsions

Claim 1

A PROCESS FOR TREATING LEATHER WHICH COMPRISES CONTACTING ONE SIDE OF THE LEATHER WITH AN AQUEOUS EMULSION CONTAINING A POLYURETHANE POLYMER SO AS TO PARTIALLY IMPREGNATE SAID LEATHER WITH FROM ABOUT 1.0 TO 10.0 GRAMS OF SAID POLYURETHANE POLYMER PER SQUARE FOOT OF SAID LEATHER, DRYING SAID IMPREGNATED LEATHER AND CURING SAID POLYURETHANE POLYMER, SAID AQUEOUS EMULSION BEING PREPARED BY EMULSIFYING A FLUID ISOCYANATE-TERMINATED POLYURETHANE POLYMER IN AN AQUEOUS MEDIUM AT TEMPERATURES BETWEEN 20* AND 95*C. WITH AGITATION IN THE PRESENCE OF A WATER-SOLUBLE ORGANIC EMULSIFYING AGENT OF THE TYPE WHICH WILL GIVE AN OIL-INWATER EMULSION; SAID EMULSION BEING APPLIED TO THE LEATHER AT TEMPERATURES BETWEEN 20* AND 70*C. WITHIN 24 HOURS OF ITS PREPARATION; SAID ISOCYANATE-TERMINATED POLYURETHANE POLYMER BEING THE REACTION PRODUCT OF (1) A MOLAR EXCESS OF AN AROMATIC POLYISOCYANATE AND (2) AN ORGANIC POLYOL SELECTED FROM THE GROUP CONSISTING OF AT LEAST ONE HYDROXYL-TERMINATED ORGANIC POLYMER HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 750 AND ABOUT 4000 AND MIXTURES OF SAID ORGANIC POLYMER WITH UP TO ABOUT .20 PERCENT BY WEIGHT OF SAID POLYMER OF AT LEAST ONE ALIPHATIC POLYOL HAVING A MOLECULAR WEIGHT BETWEEN 62 AND ABOUT 350, SAID ALIPHATIC POLYOL BEING SEHYDROXYL GROUPS, WHEREIN N IS AN INTEGER HAVING A VALUE OF AT LEAST 2 WITH N-2 OF SAID HYDROXYL GROUPS BEING CROSSLINKING HYDROXYL GROUPS; THE RELATIVE PROPORTIONS OF SAID AROMATIC POLYISOCYANATE AND SAID ORGANIC POLYOL BEING SELECTED SO THAT THE RATIO OF THE NUMBER OF FREE ISOCYANATE GROUPS TO THE TOAL NUMBER OF HYDROXYL GROUPS HAS A VALUE RANGING BETWEEN ABOUT 1.2 AND ABOUT 2.0F THERE BEING AN AVERAGE OF NO MORE THAN ABOUT ONE CROSS-LINKING HYDROXYL GROUP FOR EACH 1200 MOLECULAR WEIGHT UNITS OF SAID ISOCYANATE-TERMINATED POLYURETHANE POLYMER; SAID ORGANIC POLYMER BEING SELECTED FROM THE GROUP CONSISTING OF POLYALKYLENEETHER GLYCOLS, POLYALKYLENEETHER-ARYLENEETHER, GLYCOLS, POLYALKYLENEETHER-THIOETHER GLYCOLS, POLYALKYLENEARYLENEETHER-THIOETHER GLYCOLS, POLYESTER POLYOLS, FATTY ACID TRIGLYCERIDES HAVING A HYDROXYL NUMBER OF AT LEAST 49, AND REACTION PRODUCTS OF ALKYLENE OXIDES WITH HYDROCARBON TWEEN ABOUT 44 AND ABOUT 250, SAID HYDROCARBON POLYOLS HAVING MOLECULAR WEIGHTS BETWEEN ABOUT 62 AND 350.