Sizing fibrous materials with modified urea-formaldehyde resin

Claim 1

A METHOD OF MAKING PAPER HAVING SUBSTANTIAL WET STRENGTH BY REASON OF A CONTENT OF 0.15% OF A CURED AREA-FORMALDEHYDE RESIN IMPREGNATED UNIFORMLY THEREIN WHICH COMPRISES PREPARING A WATER SUSPENSION OF PAPER MAKING FIBERS, ADDING TO SAID SUSPENSION AN AQUEOUS SOLUTION OF A PARTIALLY POLYMERIZED HYDROPHILIC UREAFORMALDEHYDE-SULFITE RESIN COLLOID, PRECIPITATING SAID RESIN OR SAID FIBERS IN AMOUNTS OF 0.1-5% BY WEIGHT THEREOF, FORMING THE RESIN-CONTAINING FIBERS INTO A WATERLAID PRODUCT, AND HEATING THE WET, WATERLAID FIBER PRODUCT SO FORMED TO CURE THE UREA-FORMALDEHYDE-SULFITE RESIN IN SITU IN THE FELTED FIBERS WHILE SIMULTANEOUSLY DRYING THE SAME, THE SAID SIMULTANEOUS CURING OF THE RESIN AND DRYING OF THE FELTED FIBERS BEING EFFECTED BY SUBJECTING THE WET, WATERLAID PRODUCT TO A TEMPERATURE BETWEEN 180* AND 300* F. FOR NOT MORE THAN FIVE MINUTES, THE TIME AND TEMPERATURE OF SUCH HEATING BEING SUFFICIENT TO CURE THE RESIN TO A WATER-INSOLUBLE CONDITION CAPABLE OF IMPARTING IMPROVED WET STRENGTH TO THE FELTED FIBER PRODUCT AND TO PRODUCE A DRY, WATERLAID FIBER PRODUCT CONTAINING FELTED FIBERS BONDED TOGETHER BY THE SOCURED RESIN.

Claim 2

A METHOD OF MAKING PAPER HAVING SUBSTANTIAL WET STRENGTH BY REASON OF A CONTENT OF 0.15% OF A CURED AREA-FORMALDEHYDE RESIN IMPREGNATED UNIFORMLY THEREIN WHICH COMPRISES PREPARING A WATER SUSPENSION OF PAPER MAKING FIBERS, ADDING TO SAID SUSPENSION AN AQUEOUS SOLUTION OF A PARTIALLY POLYMERIZED HYDROPHILIC UREAFORMALDEHYDE-SULFITE RESIN COLLOID, PRECIPITATING SAID RESIN OR SAID FIBERS IN AMOUNTS OF 0.1-5% BY WEIGHT THEREOF, FORMING THE RESIN-CONTAINING FIBERS INTO A WATERLAID PRODUCT, AND HEATING THE WET, WATERLAID FIBER PRODUCT SO FORMED TO CURE THE UREA-FORMALDEHYDE-SULFITE RESIN IN SITU IN THE FELTED FIBERS WHILE SIMULTANEOUSLY DRYING THE SAME, THE SAID SIMULTANEOUS CURING OF THE RESIN AND DRYING OF THE FELTED FIBERS BEING EFFECTED BY SUBJECTING THE WET, WATERLAID PRODUCT TO A TEMPERATURE BETWEEN 180* AND 300* F. FOR NOT MORE THAN FIVE MINUTES, THE TIME AND TEMPERATURE OF SUCH HEATING BEING SUFFICIENT TO CURE THE RESIN TO A WATER-INSOLUBLE CONDITION CAPABLE OF IMPARTING IMPROVED WET STRENGTH TO THE FELTED FIBER PRODUCT AND TO PRODUCE A DRY, WATERLAID FIBER PRODUCT CONTAINING FELTED FIBERS BONDED TOGETHER BY THE SOCURED RESIN.