Formaldehyde-dicyandiamide resins and the treatment of leather therewith

Claim 1

THE WATER INSOLUBLE REACTION PRODUCT OF A WATER SOLUBLE RESINOUS CONDENSATION PRODUCT OF FORMALDEHYDE AND DICYANDIAMIDE WITH AN ANIONIC WATER SOLUBLE COMPOUND SELECTED FROM THE GROUP CONSISTING OF ORGANIC SULFONIC ACIDS AND THEIR SALTS AND ESTERS, THE SAID RESINOUS CONDENSATION PRODUCT BEING THE PRODUCT OF FORMING A MIXTURE OF DICYANDIAMIDE AND AN AQUEOUS SOLUTION OF FORMALDEHYDE IN THE PROPORTION OF 3.6 TO 5 MOLS OF FORMALDEHYDE TO 1 MOL OF THE DICYANDIAMIDE, HEATING THE MIXTURE AT A PH ABOVE 7, MAINTAINING THE TOTAL FREE AND REACTED FORMALDEHYDE DURING THE HEATING STEP IN THE PROPORTION OF 3.6 TO 5 MOLS, CONTINUING THE HEATING UNTIL THE CONDENSATION PRODUCT FORMED BECOMES INSOLUBLE IN WATER ON EXTREME DILUTION AND THEN LATER BECOMES SOLUBLE ON SUCH DILUTION, AND THEN DISCONTINUING THE HEATING WHEN THE WATER SOLUBLE STAGE IS REACHED.