Process of treating polyvinyl alcohol fibers

Claim 1

A METHOD FOR IMPROVING THE WATER INSENSITIVITY OF POLYVINYL ALCOHOL FIBERS HAVING ALCOHOLIC HYDROXYL GROUPS ON ONE HALF OF THE CABONS OF THE POLYMERIC CHAIN, SAID PROCESS COMPRISING HEATING IN RELAXED CONDITION AN ORIENTED FIBER OF SAID POLYMER TO A TEMPERATURE OF FROM 180*C. TO 225*C., ALLOWING THE FIBER TO SHRINK DURING SAID HEATING, CONTINUING SAID HEATING UNTIL THE FIBER SHRINKS FROM 8% TO 60% OF ITS ORIENTED LENGTH, SWELLING THE SHRUNKEN FIBER BY CONTACTING IT, WHILE PREVENTING SHRINKAGE BEYOND 60% OF THE ORIGINAL ORIENTED LENGTH, WITH INERT LIQUID AQUEOUS MEDIUM CONTAINING AT LEAST 5% WATER AND SELECTED FROM THE CLASS CONSISTING OF WATER AND AQUEOUS ALCOHOL UNTIL THE FIBER, IS SUBSTANTIALLY SATURATED, AND INSOLUBILIZING THE FIBER, WHILE PREVENTING SHRINKAGE BEYOND SAID 60%, BY IMPREGNATING WITH AN ALDEHYDE, IN SOLUTION, AT A TEMPERATURE OF 0-150*C. IN THE PRESENCE OF AN ACID CATALYST.

Claim 2

A METHOD FOR IMPROVING THE WATER INSENSITIVITY OF POLYVINYL ALCOHOL FIBERS HAVING ALCOHOLIC HYDROXYL GROUPS ON ONE HALF OF THE CABONS OF THE POLYMERIC CHAIN, SAID PROCESS COMPRISING HEATING IN RELAXED CONDITION AN ORIENTED FIBER OF SAID POLYMER TO A TEMPERATURE OF FROM 180*C. TO 225*C., ALLOWING THE FIBER TO SHRINK DURING SAID HEATING, CONTINUING SAID HEATING UNTIL THE FIBER SHRINKS FROM 8% TO 60% OF ITS ORIENTED LENGTH, SWELLING THE SHRUNKEN FIBER BY CONTACTING IT, WHILE PREVENTING SHRINKAGE BEYOND 60% OF THE ORIGINAL ORIENTED LENGTH, WITH INERT LIQUID AQUEOUS MEDIUM CONTAINING AT LEAST 5% WATER AND SELECTED FROM THE CLASS CONSISTING OF WATER AND AQUEOUS ALCOHOL UNTIL THE FIBER, IS SUBSTANTIALLY SATURATED, AND INSOLUBILIZING THE FIBER, WHILE PREVENTING SHRINKAGE BEYOND SAID 60%, BY IMPREGNATING WITH AN ALDEHYDE, IN SOLUTION, AT A TEMPERATURE OF 0-150*C. IN THE PRESENCE OF AN ACID CATALYST.