Polyethylenimine adhesive

Claim 1

AN ADHESIVE COMPOSITION SUITABLE FOR STRONGLY BONDING A PLASTIC FILM ONTO A SUBSTRATE WHICH COMPRISES, A SUBSTANTIALLY NON-GELLING WATER SOLUTION OF POLYETHYLENIMINE AND A WATER-SOLUBLE LOWER ALDEHYDE IN AN AMOUNT RANGING BY WEIGHT FROM ABOUT 1% TO 15% POLYETHYLENIMINE AND ABOUT 0.2% TO 5% ALDEHYDE, SAID SOLUTION ALSO CONTAINING ABOUT 0.015% TO 6% BY WEIGHT OF A WATER-SOLUBLE ALIPHATIC CARBOXYLIC ACID CONTAINING UP TO 6 CARBON ATOMS, SAID AMOUNT BEING BASED ON THE CARBONYL RADICAL OF SAID ACID, THE AMOUNT OF SAID ACID BEING EFFECTIVE WHEN ADDED DURING THE THE FORMULATION OF SAID COMPOSITION BEFORE THE ADDITION OF SAID LOWER ALDEHYDE TO INHIBIT GEL FORMATION OF SAID ADHESIVE COMPOSITION DUE TO THE SUBSEQUENT ADDITION OF SAID ALDEHYDE, THE AMOUNT OF ACID EMPLOYED INCREASING WITH INCREASED AMOUNTS OF POLYETHYLEIMINE OVER SAID RENGES, SAID COMPOSITION ALSO CONTAINING BY WEIGHT 0.01% TO 1% OF THICKENER SELECTED FROM THE GROUP CONSISTING OF HYDROXYETHYLCELLULOSE, POLYVINYL ALCOHOL AMD METHYL CELLULOSE, ABOUT 0.03% TO 2% OF CURING AGENT SELECTED FROM THE GROUP CONSISTING OF MELAMINE-FORMALDEHYDE AND UREAFORMALDEHYDE AND ABOUT 0.005% TO 0.1% OF A DEFOAMING AGENT.

Claim 7

A method of inhibiting the gelation of a water solution of polyethylenimine and an aldehyde which comprises, first forming a solution of about 1% to 15% by weight of polyethylenimine in water, acidifying said solution with a water-soluble aliphatic carboxylic acid containing up to 6 carbon atoms in an amount ranging by weight from about 0.015% to 6% of the carboxyl radical effective to inhibit gelation of said solution when a gelation-forming amount of about 0.2% to 5% by weight of a lower aldehyde is subsequently added to said polyethylenimine solution, and following the addition of said carboxylic acid then adding said aldehyde to said acidified solution in an amount which would normally cause gelation to occur, the amount of acid employed increasing with increased amounts of polyethylenimine over said ranges.

Claim 8

A method of inhibiting the gelation of a water solution of polyethylenimine and an aldehyde which comprises, first forming a solution of about 1% to 15% by weight of polyethylenimine in water, acidifying said solution with a water-soluble aliphatic carboxylic acid containing up to 6 carbon atoms in an amount ranging by weight from about 0.015% to 6% of the carboxyl radical effective to inhibit gelation of said solution when a gelation-forming amount of about 0.2% to 5% by weight of a lower aldehyde is subsequently added to said polyethylenimine solution, and following the addition of said carboxylic acid then adding said aldehyde to said acidified solution in an amount which would normally cause gelation to occur, the amount of acid employed increasing with increased amounts of polyethylenimine over said ranges.