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1. WO2004054796 - STRUCTURE DE FILM SCELLABLE ET DEPELLICULABLE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

WHAT IS CLAIMED IS:

1. An oriented sealable and peelable film, comprising:
(a) a first outer layer comprising a thermoplastic polymer;
(b) a core layer comprising a peelable blend comprising (i) from 20-80 wt% of a polyethylene and (ii) from 80-20 wt% of a polyolefin incompatible with polyethylene (i) of core layer (b); and
(c) a sealable second outer layer comprising a thermoplastic polymer, wherein sealable second outer layer (c) is positioned such that core layer (b) is between first outer layer (a) and sealable second outer layer (c).

2. The film of claim 1, further comprising:
an intermediate layer comprising a propylene homopolymer, wherein the intermediate layer is positioned such that core layer (b) is between first outer layer (a) and the intermediate layer.

3. The film according to any of the preceding claims, wherein the polyethylene (i) of core layer (b) is selected from the group consisting of linear ethylene homopolymer, linear ethylene-α-olefin copolymer, single-site metallocene-catalyzed ethylene homopolymer, single-site metallocene-catalyzed ethylene-α-olefin copolymer, ethylene-α-olefin block copolymer, ethylene-propylene impact copolymer, and blends thereof.

4. The film of claim 3, wherein the α-olefin of the linear ethylene-α-olefin copolymer and the α-olefin of the single-site metallocene-catalyzed ethylene-α-olefin copolymer are independently selected from the group consisting of C4-C12 α-olefϊns.

5. The film according to any of the preceding claims, wherein the polyethylene (i) of core layer (b) is ethylene-hexene copolymer.

6. The film according to any of the preceding claims, wherein the polyethylene (i) of core layer (b) is ethylene-octene copolymer.

7. The film according to any of the preceding claims, wherein the polyolefin (ii) incompatible with the polyethylene (i) of core layer (b) is propylene homopolymer.

8. The film according to any of the preceding claims, wherein the thermoplastic polymer of the sealable second outer layer is selected from the group consisting of ethylene-propylene random copolymer, ethylene-propylene-butene-1 terpolymer, propylene-butene copolymer, low density polyethylene (LDPE), linear ethylene-α-olefm copolymer, single-site metallocene-catalyzed ethylene-α-olefin copolymer, ethylene-methacrylic acid copolymer, ethylene-vinyl acetate copolymer, ionomer, and blends thereof.

9. The film according to any of the preceding claims, wherein the thermoplastic polymer of first outer layer (a) is a propylene homopolymer or a propylene copolymer.

10. The film according to any of the preceding claims, wherein core layer (b) comprises a peelable blend comprising (i) from 20-40 wt% of a polyethylene selected from the group consisting of high density polyethylene (HDPE), ethylene-butene copolymer, ethylene-pentene copolymer, ethylene-hexene copolymer, ethylene-heptene copolymer, ethylene-octene copolymer, single-site metallocene-catalyzed ethylene homopolymer, single-site metallocene-catalyzed ethylene-hexene copolymer, single-site metallocene-catalyzed ethylene-octene copolymer, single-site metallocene-catalyzed plastomer, ethylene-α-olefm block copolymer, ethylene-propylene impact copolymer, and blends thereof and (ii) from 80-60 wt% of propylene homopolymer.

11. The film according to any of the preceding claims, wherein core layer (b) is from 7.5 to 70 μm thick and intermediate layer (c) is from 1 to 3 μm thick.

12. The film according to any of the preceding claims, wherein one or both of an outer surface of first outer layer (a) and an outer surface of second outer layer (d) is surface-treated by a treatment selected from the group consisting of corona discharge treatment, flame treatment, and plasma treatment.

13. The film according to any of the preceding claims, wherein an outer surface of first outer layer (a) has applied thereon a coating selected from the group consisting of ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMA), alkyl acrylate copolymer, acrylonitrile, polyvinylidene chloride (PVdC), polyvinyl alcohol (PVOH), and urethane copolymer.

14. The film according to any of the preceding claims, wherein a metal layer is coated on an outer surface of first outer layer (a) by vacuum metallization.

15. The film according to any of the preceding claims, wherein the film has a ratio of plateau crimp seal strength to peak crimp seal strength of greater than 60% and less than 100%.

16. The film according to any of the preceding claims, wherein core layer (b) further comprises from 1 wt% to 5 wt% of an ethylene-α-olefin elastomer.

17. The film according to any of the preceding claims, wherein the peelable blend of the core layer comprises:

(i) from 10-35 wt% of ethylene-α-olefin elastomer, and (ii) from 90-65 wt% of propylene homopolymer.

18. The film of claim 1 , prepared by a method comprising the steps of:
(a) coextruding melts corresponding to the thermoplastic polymer of first outer layer (a), the peelable blend of core layer (b), and the thermoplastic polymer of sealable second outer layer (c);
(b) quenching the melts to form a coextruded sheet; and
(c) biaxially orienting the coextruded sheet to form a sealable and peelable film.