초록 ▼

Molecularly oriented plastic films have five molecularly oriented layers. A first layer provides a barrier to gaseous transmission through the film and has a composition of 0% to 50% nylon or nylon copolymer, and conversely 50% to 100% ethylene vinyl alcohol. Second and third adhesive layers are adh

Molecularly oriented plastic films have five molecularly oriented layers. A first layer provides a barrier to gaseous transmission through the film and has a composition of 0% to 50% nylon or nylon copolymer, and conversely 50% to 100% ethylene vinyl alcohol. Second and third adhesive layers are adhered to the surfaces of the first layer, and have compositions comprising olefinic polymers, or copolymers, or blends thereof, the compositions having carboxyl modifications therein. Fourth and fifth layers are adhered to the second and third layers on the respective surfaces opposite the first layer. The fourth and fifth layers comprise 40% to 100% ethylene vinyl acetate and 0% to 60% linear low density polyethylene. Also disclosed are processes for making the oriented five layer films.

대표청구항 ▼

1. A method of making a five layer oriented polymeric film, said method comprising the steps of: (a) coextruding a five layer film having a first barrier layer, the composition of said first layer being 10% to 50% nylon or nylon copolymer and 90% to 50% ethylene vinyl alcohol, said first layer hav

1. A method of making a five layer oriented polymeric film, said method comprising the steps of: (a) coextruding a five layer film having a first barrier layer, the composition of said first layer being 10% to 50% nylon or nylon copolymer and 90% to 50% ethylene vinyl alcohol, said first layer having two opposing surfaces; second and third adhesive layers adhered to said surfaces of said first layer, said second and third adhesive layers both comprising olefinic polymers or copolymers having carboxyl modifications thereto; and fourth and fifth layers adhered to said second and third layers on the respective surfaces opposite said first layer, said fourth and fifth layers comprising 40% to 100% ethylene vinyl acetate and 60% to 0% linear low density polyethylene; (b) cooling said five layer film; (c) reheating said five layer film to molecular orientation temperatures; (d) molecularly orienting said five layer film; and (e) cooling said molecularly oriented five layer film; said oriented film being susceptible to being made into a closed and sealed container by means of heat seals formed along terminal edges of adjacent superimposed sheets thereof. 2. A method of making a five layer oriented polymeric film, said method comprising the steps of: (a) coextruding a five layer film having a first barrier layer, the composition of said first layer being 10% to 50% nylon or nylon copolymer and 90% to 50% ethylene vinyl alcohol, said first layer having two opposing surfaces; second and third adhesive layers adhered to said surfaces of said first layer, said second and third adhesive layers both comprising olefinic polymers or copolymers having carboxyl modifications thereto; and fourth and fifth layers adhered to said second and third layers on the respective surfaces opposite said first layer, said fourth and fifth layers comprising 40% to 100% ethylene vinyl acetate and 60% to 0% linear low density polyethylene; (b) cooling said five layer film; (c) reheating said five layer film to molecular orientation temperature; (d) molecularly orienting said five layer film; (e) heat setting said molecularly oriented film; and (f) cooling said molecularly oriented film. 3. A method of making a five layer oriented film as in claim 1 or 2 wherein said film is coextruded in the shape of a tube and is oriented by introducing into said tube a pressurized gas, and drawing said tube between two nips having a differential rate of speed therebetween, such that the pressure of said gas and the drawing of said nips effect the molecular orientation of said film as an expanded tube. 4. A method of making a five layer oriented film as in claim 3 and wherein said fourth and fifth layers comprise a blend of 10% to 60% linear low density polyethylene and 90% to 40% ethylene vinyl acetate. 5. A method of making a five layer oriented film as in claim 3 and wherein said first layer is 40% nylon and 60% ethylene vinyl alcohol. 6. A method of making a five layer oriented film as in claim 3 and wherein the compositions of said second and third layers are chosen from the group consisting of modified low density polyethylene, modified linear low density polyethylene, modified medium density polyethylene, modified ethylene vinyl acetate, and blends of said herein recited polymers and copolymers, the compositions of said fourth and fifth layers comprising blends of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 7. A method of making a five layer oriented film as in claim 3 and wherein said first layer is 30% to 50% nylon and 70% to 50% ethylene vinyl alcohol. 8. A method of making a five layer film as in claim 7 and wherein the compositions of said second and third layers are chosen from the group consisting of modified low density polyethylene, modified linear low density polyethylene, modified medium density polyethylene, modified ethylene vinyl acetate, and blends of said herein recited polymers and copolymers, the compositions of said fourth and fifth layers comprising blends of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 9. A method of making a five layer oriented film as in claim 3 and wherein said first layer consists essentially of ethylene vinyl alcohol. 10. A method of making a five layer film as in claim 9 and wherein the compositions of said second and third layers are chosen from the group consisting of modified low density polyethylene, modified linear low density polyethylene, modified medium density polyethylene, modified ethylene vinyl acetate, and blends of said herein recited polymers and copolymers, the compositions of said fourth and fifth layers comprising blneds of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 11. A method of making a five layer oriented polymeric film as in claim 1 or 2 and wherein said first layer is 30% to 50% nylon and 70% to 50% ethylene vinyl alcohol. 12. A method of making a five layer oriented film as in claim 11 and wherein said fourth and fifth layers comprise a blend of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 13. A method of making a five layer oriented film as in claim 11 and wherein the compositions of said second and third layers are chosen from the group consisiting of modified low density polyethylene, modified linear low density polyethylene, modified medium density polyethylene, modified ethylene vinyl acetate, and blends of said herein recited polymers and copolymers, the compositions of said fourth and fifth layers comprising blends of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 14. A method of making a five layer oriented polymeric film as in claim 1 or 2 and wherein said first layer is 40% nylon and 60% ethylene vinyl alcohol. 15. A method of making a five layer oriented polymeric film as in claim 1 or 2 and wherein said first layer consists essentially of ethylene vinyl alcohol. 16. A method of making a five layer film as in claim 15 and wherein the compositions of said second and third layers are chosen from the group consisting of modified low density polyethylene, modified linear low density polyethylene, modified medium density polyethylene, modified ethylene vinyl acetate and blends of said herein recited polymers and copolymers, the compositions of said fourth and fifth layers comprising blends of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 17. A method of making a five layer oriented film as in claim 1 or 2 and wherein the compositions of said second and third adhesive layers are chosen from the group consisting of modified low density polyethylene, modified linear low density polyethylene, modified medium density polyethylene, modified ethylene vinyl acetate, and blends of said herein recited polymers and copolymers; the compositions of said fourth and fifth layers comprising blends of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 18. A method of fabricating a plastic bag having an opening on one edge thereof; the remainder of the periphery of said bag having been closed by heat seals at terminal edges thereof, said method comprising the steps of: (a) coextruding a five layer film having a first barrier layer, the composition of said first layer being 10% to 50% nylon or nylon copolymer and 90% to 50% ethylene vinyl alcohol, said first layer having two opposing surfaces; second and third adhesive layers adhered to said surfaces of said first layer, said second and third adhesive layers both comprising olefinic polymers or copolymers having carboxyl modifications thereto; and fourth and fifth layers adhered to said second and third layers on the respective surfaces opposite said first layer, said fourth and fifth layers comprising 40% to 100% ethylene vinyl acetate and 60% to 0% linear low density polyethylene; (b) cooling said five layer film; (c) reheating said five layer film to molecular orientation temperature; (d) molecularly orienting said five layer film; (e) cooling said molecularly oriented five layer film; and (f) forming heat seals around the periphery of said bag at terminal edges thereof, but not along said one edge; said bag being susceptible to being closed by means of a heat seal along said opening. 19. A method of fabricating a plastic bag as in claim 18 and including, after step (d), and before step (e), the additional step of heat setting the oriented film by holding it at an elevated temperature of 200° to 250° Fahrenheit for at least 2 seconds. 20. A method of fabricating a plastic bag as in claim 18 or 19 wherein said first layer is 30% to 50% nylon and 70% to 50% ethylene vinyl alcohol. 21. A method of fabricating a plastic bag as in claim 18 or 19 wherein said first layer consists essentially of ethylene vinyl alcohol. 22. A method of fabricating a plastic bag as in claim 20 and wherein said foruth and fifth layers comprise a blend of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate. 23. A method of fabricating a plastic bag as in claim 18 or 19 and wherein the compositions of said second and third adhesive layers are chosen from the group consisting of modified low density polyethylene, modified linear low density polyethylene, modified medium density polyethylene, modified ethylene vinyl acetate, and blends of said herein recited polymers and copolymers; the compositions of said fourth and fifth layers comprising blends of 25% to 40% linear low density polyethylene and 75% to 60% ethylene vinyl acetate.