Abstract A process and apparatus for laminating an oriented, surfaceconditioned, thermoplastic film to a wet cellulose film by (a) heating and steam-sparging the thermoplastic film; (b) impregnating the wet cellulose film with an anchoring agent when the cellulose film contains about 180 to 350 % moisture; (c) drying the cellulose film to a moisture content of about 10 to 40 weight per cent; (d) laminating the surface-conditioned, steamsparged side of the thermoplastic film to the impregnated side of the cellulose film when the cellulose film has a moisture content of about 10 to 40 weight per cent conveniently carried out by simultaneously passing the two films through a set of heated nip rolls; then (e) drying the laminated film structure until the cellulose film contains about 3 to 8 weight per cent moisture where the weight per cent moisture is based on the weight of the moisture-free cellulose content thereof. This laminated film structure can be coated with a vinylidene chloride type coating making it particularly useful in packaging dry foodstuffs, such as cereals and snacks.
The process of claim 1 wherein the thermoplastic film is heated to a temperature of about 50* to 60* C. before it is steam sparged.
Claim 2
Dependent Claim
31 words
The process of claim 1 wherein steam sparging of the thermoplastic film takes place about 4 to 6 inches away from the nip prior to the thermoplastic film entering the nip.
Claim 3
Dependent Claim
40 words
The process of claim 1 wherein the impregnated anchoring agent is a polyalkylenimine having from 2 to 8 carbon atoms and present in the amount of about 0.05 to 2 weight percent of the total weight of the cellulose film.
Claim 4
Dependent Claim
11 words
The process of claim 1 wherein the thermoplastic film is polyethylene.
Claim 5
Dependent Claim
11 words
The process of claim 1 wherein the thermoplastic film is polypropylene.
Claim 6
Dependent Claim
12 words
The process of claim 1 wherein the thermoplastic film is polyethylene terephthalate.
Claim 7
Dependent Claim
45 words
The process of claim 1 wherein the nip roll contacted by the cellulose has a metal surface and is heated to a temperature of about 90* to 220* C. and the nip roll contacting the thermoplastic film is not heated and has an elastomeric cover.
Claim 8
Dependent Claim
11 words
The process of claim 6 wherein both nip rolls are heated.
Claim 9
Independent Claim
216 words
An apparatus for laminating an oriented, surface-conditioned and steam-sparged, thermoplastic film to an impregnated, wet, cellulose film comprising: a. means for advancing a moisture-laden, gel-regenerated, cellulose film; b. means for impregnating the cellulose film with an anchoring agent when tHe cellulose film has been dried to a moisture content of about 180 to 350 weight per cent; c. means for partially drying the cellulose film to a moisture content of about 10 to 15 weight per cent; d. means for advancing an oriented, surface-conditioned, thermoplastic film; e. means for steam-sparging the thermoplastic film; f. means for laminating the steam-sparged thermoplastic film to the cellulose film having a moisture content of about 15 to 40 weight per cent by simultaneously passing the thermoplastic film and the cellulose film through nip rolls with an impregnated side of the cellulose film contacting the surface-conditioned, steam-sparged side of the oriented thermoplastic film wherein the temperature of at least one nip roll is about 90* to 230* C. and the pressure in the nip is at least about 50 pounds per linear inch; and g. means for drying the laminated film structure until the cellulose film contains about 3 to 8 weight per cent moisture, where all percentages of moisture are based on the weight of the moisture-free cellulose content thereof.
Claim 10
Dependent Claim
26 words
The apparatus of claim 10 including means for heating the thermoplastic film to a temperature of about 50* to 60* C. before it is steam sparged.
Claim 11
Dependent Claim
22 words
The apparatus of claim 10 wherein one nip roll has a metal surface and the other nip roll has an elastomeric surface.