Flex-crack resistant and thermally resistant aseptic bulk bags for flexible packaging
This invention relates to inner-plies for bulk-bags that surprisingly offer not only high thermal resistance, but also high flex-crack resistance. This invention also relates to such bulk-bags made for packaging of flowable materials, aseptic or otherwise, and the process for improving their flex-crack and thermal resistance. Preferably, the packaging is aseptic. More specifically, the inner-ply of the invention comprises a resin blend comprising the Exceed® XP resin; an LDPE resin or an ethylene—α-olefin copolymer (EAO copolymer); or a blend of said LDPE resin and said EAO copolymer, with flex-crack resistance improved in both machine direction and transverse direction, in conjunction with an improved thermal resistance. Thus, in addition to possessing good flex-crack resistance, the bulk-bags can withstand steam sterilization and/or aseptic packaging conditions.
1. A flex-crack resistant, and thermally resistant bag for aseptic packaging of flowable materials, wherein said bag comprises at least one ply, wherein said at least one ply comprises a film made from a resin blend comprising:
(a) at least 60% of a resin comprising an ethylene-hexene-1 copolymer and an ethylene-α-olefin copolymer blend having a density range from 0.914 to 0.918 g/cm 3 and a melt index range of 0.20 to 1.0 dg/min; and
(b) one of the following three components:
(i) from 0-40% of LDPE;
(ii) from 0-40% of EAO copolymer; and
(iii) from 0-40% of a blend of LDPE and said EAO copolymer;
wherein said resin blend comprises an overall density of at least 0.915 g/cm 3 ; and
wherein said bag has flex-crack resistance such that said film develops less than 10 pinholes per 300 cm 2 in 8,100 cycles in both machine direction and transverse direction in a Gelbo Flex Test as measured according to ASTM F392, wherein the HDPE peak-melting endotherm as percentage of the total melting endotherm, in a DSC measurement, of the resin blend is in the range of from about 40 to about 60.
2. The bag according to claim 1 , comprising at least two plies, wherein one of the at least two plies comprises an outer, or skin layer, comprising a film made from a resin blend comprising:
(a) at least 60% of a resin comprising an ethylene-hexene-1 copolymer and an ethylene-α-olefin copolymer blend having a density range from 0.914 to 0.918 g/cm 3 and a melt index range of 0.20 to 1.0 dg/min; and
(b) one of the following three components:
(i) from 0-40% of LDPE;
(ii) from 0-40% of EAO copolymer; and
(iii) from 0-40% of a blend of LDPE and said EAO copolymer;
wherein said resin blend comprises an overall density of at least 0.915 g/cm 3 ; and
wherein said bag has flex-crack resistance such that said film develops less than 10 pinholes per 300 cm 2 in 8,100 cycles in both machine direction and transverse direction in a Gelbo Flex Test as measured according to ASTM F392, wherein the HDPE peak-melting endotherm as percentage of the total melting endotherm, in a DSC measurement, of the resin blend is in the range of from about 40 to about 60.
3. The bag according to claim 1 , wherein the EAO copolymer content is up to 40%.
4. The bag according to claim 1 , wherein the size of said bag ranges from 2 gallons to 20 gallons.
5. The bag according to claim 1 , wherein said at least one ply has a thickness in the range of 20 μm to 140 μm thickness.
6. The bag according to claim 1 , comprising flowable material.
7. The bag according to claim 1 , wherein said bag is a steam-sterilization bag for aseptic processes, an ESL, hot-fill, or pasteurization bag.
8. The bag according to claim 1 , wherein the HDPE peak-melting endotherm as percentage of the total melting endotherm, in a DSC measurement, of the resin blend is in the range of from about 50 to about 60.
9. The bag according to claim 1 , wherein said film develops less than 5 pinholes per 300 cm 2 in 8,100 cycles in both machine direction and transverse direction in a Gelbo Flex Test as measured according to ASTM F392.
10. The bag according to claim 9 , wherein the LDPE content is in the range of from about 5% to about 20%.
11. The bag according to claim 10 , wherein the LDPE content is in the range of from about 10% to about 15%.
12. The bag according to claim 10 , wherein said EAO copolymer is a butene-LLDPE resin, in a density range of from about 0.818-0.922 g/cm 3 .
13. The bag according to claim 1 , wherein the bag further comprises a structure having from 3-7 layers, and wherein at least one of the layers comprises a barrier layer.
14. The bag according to claim 13 , wherein the barrier layer comprises PET or met-PET.
15. A process for making a bag, comprising:
(I) providing at least one ply, wherein said at least one ply comprises a film made from a resin blend comprising:
(a) at least 60% of a resin comprising an ethylene-hexene-1 copolymer and an ethylene-α-olefin copolymer blend having a density range from 0.914 to 0.918 g/cm 3 and a melt index range of 0.20 to 1.0 dg/min; and
(b) one of the following three components:
(i) from 0-40% of LDPE;
(ii) from 0-40% of EAO copolymer; and
(iii) from 0-40% of a blend of LDPE and said EAO copolymer;
wherein said resin blend comprises an overall density of at least 0.915 g/cm 3 ; and
wherein said bag has flex-crack resistance such that said film develops less than 10 pinholes per 300 cm 2 in 8,100 cycles in both machine direction and transverse direction in a Gelbo Flex Test as measured according to ASTM F392, wherein the HDPE peak-melting endotherm as percentage of the total melting endotherm, in a DSC measurement, of the resin blend is in the range of from about 40 to about 60.
16. The process according to claim 15 , comprising:
(I) providing at least two plies, wherein one of the at least two plies comprises an outer, or skin layer, comprising a film made from a resin blend comprising:
(a) at least 60% of a resin comprising an ethylene-hexene-1 copolymer and an ethylene-α-olefin copolymer blend having a density range from 0.914 to 0.918 g/cm 3 and a melt index range of 0.20 to 1.0 dg/min; and
(b) one of the following three components:
(i) from 0-40% of LDPE;
(ii) from 0-40% of EAO copolymer; and
(iii) from 0-40% of a blend of LDPE and said EAO copolymer;
wherein said resin blend comprises an overall density of at least 0.915 g/cm 3 ; and
wherein said bag has flex-crack resistance such that said film develops less than 10 pinholes per 300 cm 2 in 8,100 cycles in both machine direction and transverse direction in a Gelbo Flex Test as measured according to ASTM F392, wherein the HDPE peak-melting endotherm as percentage of the total melting endotherm, in a DSC measurement, of the resin blend is in the range of from about 40 to about 60.
17. The process according to claim 15 , wherein the EAO copolymer content is up to 40%.
18. The process according to claim 15 , wherein the size of said bag ranges from from 2 gallons to 20 gallons.
19. The process according to claim 15 , wherein said at least one ply has a thickness in the range of 20 μm to 140 μm thickness.
20. The process according to claim 15 , comprising flowable material.
21. The process according to claim 15 , wherein said bag is a steam-sterilization bag for aseptic processes, an ESL, a hot-fill, or a pasteurization bag.
22. The process according to claim 15 , wherein the HDPE peak-melting endotherm as percentage of the total melting endotherm, in a DSC measurement, of the resin blend is in the range of from about 50 to about 60.
23. The process according to claim 15 , wherein said film develops less than 5 pinholes per 300 cm 2 in 8,100 cycles in both machine direction and transverse direction in a Gelbo Flex Test as measured according to ASTM F392.
24. The process according to claim 23 , wherein the LDPE content is in the range of from about 5% to about 20%.
25. The process according to claim 24 , wherein the LDPE content is in the range of from about 10% to about 15%.
26. The process according to claim 24 , wherein said EAO copolymer is a butene-LLDPE resin, in a density range of from about 0.818-0.922 g/cm 3 .
27. The process according to claim 15 , wherein the bag further comprises a structure having from 3-7 layers, and wherein at least one of the layers comprises a barrier layer.
28. The process according to claim 27 , wherein the barrier layer comprises PET or met-PET.