Heat-sealable composite polymeric film
View Patent ↗A sealed container containing a foodstuff or beverage has a lid that includes a heat-sealable, composite film that includes a polymeric substrate layer having a first and second surface, a primer layer that includes PVdC disposed on the first surface, and a heat-sealable polymeric layer extrusion coated on the primer layer. The heat-sealable polymeric layer is 12 μm thick or less and includes a copolymer having repeating monomeric units of ethylene and at least a second type of repeating monomeric unit having the formula [—CH 2 C(R 1 )(X)—] wherein: X is selected from —COOR 2 and —OC(O)CH 3 ; R 1 =H or methyl; and R 2 is H, C 1-10 alkyl or a counterion M.
1. A sealed container containing a foodstuff or beverage, said container comprising a lid comprising a heat-sealable, peelable composite film comprising a polyester substrate layer having a first and second surface, a primer layer comprising a polymeric material and disposed on and in direct contact with the first surface of the polyester substrate layer, and a heat-sealable polymeric layer extrusion coated on the primer layer, wherein
(i) the polymeric material of the primer layer comprises poly(vinylidene chloride) (PVdC);
(ii) the thickness of the primer layer is in the range of 0.01 to 0.2 μm;
(iii) the polymeric material of the heat-sealable polymeric layer consists of a copolymer comprising repeating monomeric units of ethylene [—CH 2 CH 2 —] and at least a second type of repeating monomeric unit derived from acrylic acid, methacrylic acid and vinyl acetate having the formula [—CH 2 C(R 1 )(X)—] wherein:
X is selected from the group consisting of —COOR 2 and —OC(O)CH 3 ;
R 1 =H or methyl; and
R 2 is selected from the group consisting of H, C 1-10 alkyl and a counterion M; and
wherein the heat-sealable polymeric layer contains only a single type of said copolymer;
(iv) the thickness of the heat-sealable layer is 12 μm or less; and
(v) the water vapour transmission rate of the heat-sealable, peelable composite film is in a range of 1g/100 inches 2 /day to 10g/100 inches 2 /day.
2. The sealed container according to claim 1 wherein the Second type of repeating monomeric unit is of the formula [—CH 2 C(R 1 )(OC(O)CH 3 )—].
3. The sealed container according to claim 2 wherein the content of the second type of repeating monomeric units in the copolymer is in the range of 2% to 40% w/w.
4. The sealed container according to claim 2 wherein R 1 =H.
5. The sealed container according to claim 2 wherein the copolymer of the heat-sealable polymeric layer comprises repeating monomeric units of ethylene [—CH 2 CH 2 —] and said second type of repeating monomeric unit, and further comprises one or more further type(s) of repeating monomeric unit [—CH 2 C(R 1 )(X)—] which is/are different from the second type of repeating monomeric unit.
6. The sealed container according to claim 5 wherein the copolymer of the heat-sealable polymeric layer comprises third and fourth types of repeating monomeric unit of formula [—CH 2 C(R 1 )(X)—].
7. The sealed container according to claim 5 wherein the total amount of said one or more further type(s) of repeating monomeric unit [—CH 2 C(R 1 )(X)—] in the heat-sealable polymeric layer is in the range of 0.1% to 30% w/w.
8. The sealed container according to claim 2 wherein the copolymer of the heat-sealable polymeric layer further comprises one or more type(s) of repeating units of formula [—CH 2 C(R 1 )(COOR 2 )—] wherein R 2 is selected from the group consisting of H and M, in addition to the monomeric units of ethylene and the second type of repeating monomeric unit.
9. The sealed container according to claim 1 wherein the second type of repeating monomeric unit is of the formula [—CH 2 C(R 1 )(COOR 2 )—].
10. The sealed container according to claim 9 wherein R 2 is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl and hexyl.
11. The sealed container according to claim 9 wherein R 1 =H.
12. The sealed container according to claim 9 wherein the content of said second type of repeating monomeric unit is in the range of 2% to 30% w/w.
13. The sealed container according to claim 9 wherein the copolymer of the heat-sealable polymeric layer further comprises one or more type(s) of repeating units of formula [—CH 2 C(R 1 )(COOR 2 )—] wherein R 2 is selected from the group consisting of H and M, in addition to the monomeric units of ethylene and the second type of repeating monomeric unit.
14. The sealed container according to claim 1 wherein the second type of repeating monomeric unit is of the formula [—CH 2 C(R 1 )(COOH)—].
15. The sealed container according to claim 14 wherein the content of said second type of repeating monomeric unit is in the range of 2% to 30% w/w.
16. The sealed container according to claim 1 wherein the second type of repeating monomeric unit is of the formula [—CH 2 C(R 1 )(COOM)—].
17. The sealed container according to claim 16 wherein M is selected from the group consisting of Na, Li, K, Rb, Cs, Zn, Be, Mg, Ca, Sr, Ba and Cd.
18. The sealed container according to claim 16 wherein M is selected from the group consisting of Na and Zn.
19. The sealed container according to claim 16 wherein the copolymer of the heat-sealable polymeric layer further comprises one or more type(s) of repeating units of formula [—CH 2 C(R 1 )(COOH)—], in addition to the monomeric units of ethylene and the second type of repeating monomeric unit.
20. The sealed container according to claim 19 wherein the copolymer of the heat-sealable polymeric layer further comprises repeating units of formula [—CH 2 C(R 1 )(OC(O)CH 3 )—] or repeating units of formula [—CH 2 C(R 1 )(COOR 2 )—], wherein R 2 is selected from C 1-10 alkyl, in addition to the monomeric units of ethylene and the second type of repeating monomeric unit.
21. The sealed container according to claim 16 wherein R 1 =H.
22. The sealed container according to claim 16 wherein the content of said second type of repeating monomeric unit is in the range of 2% to 30% w/w.
23. The sealed container according to claim 1 wherein the polyester substrate layer has a thickness of from 5 to 350μm.
24. The sealed container according to claim 1 wherein the polyester substrate layer has a thickness of 25μm or less.
25. A method of forming the sealed container of claim 1 , said method comprising the step of providing the heat-sealable, peelable composite film and heat-sealing the heat-sealable composite film to the container.
26. A sealed container containing a foodstuff or beverage, said container comprising a lid comprising a heat-sealable, peelable composite film comprising a polyester substrate layer and a heat-sealable polymeric layer, with a PVdC primer layer disposed between and in direct contact with both the polyester substrate layer and the heat-sealable polymer layer, said PVdC primer layer having a thickness in the range from 0.01 to 0.2μm, wherein:
(i) the polymeric material of the heat-sealable polymeric layer consists of a copolymer comprising repeating monomeric units of ethylene [—CH 2 CH 2 —] and one or more types of repeating monomeric units having the formula [—CH 2 C(R 1 )(X)—] wherein:
X is selected from the group consisting of —COOR 2 and —OC(O)CH 3 ;
R 1 =H or methyl; and
R 2 is selected from the group consisting of H, C 1-10 alkyl and a counterion M; and
wherein the heat-sealable polymeric layer contains only a single type of said copolymer;
(ii) the thickness of the heat-sealable polymeric layer is 12 μm or less; and
(iii) the water vapour transmission rate of the heat-sealable, peelable composite film is in a range of 1g/100 inches 2 /day to 10g/100 inches 2 /day.