Process for laminating regenerated cellulose films

Claim 1

A PROCESS FOR LAMINATING REGENERATED CELLULOSE FILM WHICH COMPRISES IMPREGNATING AT LEAST TWO SEPARTED SHEETS OF REGENERATED CELLULOSE FILM, IN THE WET GEL STATE, WITH AN ACID-FREE AQUEOUS SOLUTION OF AN ACID-CATALYZABLE THERMOSETTING RESIN THAT IS PARTIALLY POLYMERIZED, WATER SOLUBLE AND CAN BE FURTHER POLYMERIZED TO A WATER INSOLUBLE FORM, OF SUFFICIENT CONCENTRATION TO LEAVE 0.15-2%, BASED ON THE DRY WEIGHT OF SAID SHEETS, ON THE SHEETS; THEREAFTER, APPLYING TO ONE OF THE IMPREGNATED SURFACES OF AT LEAST ONE OF SAID SHEETS OF REGENERATED CELLULOSE FILM AN AQUEOUS SOLUTION CONSISTING ESSENTAILLY OF A WATER SOLUBLE ORGANIC ACID HAVING AN IONIZATION CONSTANT OF 1.0X10**-6 TO 1.0X10**-2, THE AQUEOUS SOLUTION BEING APPLIED IN AN AMOUNT TO LEAVE 0.1-1% OF SAID ORGANIC ACID ONTHE SHEETS,BASED ON THE DRY WEIGHT OF SAID SHEETS; PRESSING THE ACID CONTAINING SURFACE AGAINST A SURFACE OF ANOTHER SHEET OF IMPREGANATED REGENERATED CELLULOSE FILM; AND HEATING SAID SHEETS FOR A TIME AND AT A TEMPERATURE SUFFICIENT TO FURTHER POLYMERIZE SAID ACID-CATALYZABLE THERMOSETTING RESIN, TO DRY THE SHEETS, AND TO FORM A LAMINATE.