Multilayer film for packaging fluid products
View Patent ↗Co-extruded multilayer packaging films suitable for packaging fluid products, showing a very good balance of mechanical, chemical and, optionally, barrier properties, good sealability, heat resistance and unexpectedly improved optical properties, a process for their manufacturing, pouches and packages obtained from them, are disclosed. These films comprise a core layer (D) comprising a polyamide; two tie layers (C), directly adhered to the opposite surfaces of the core layer; at least one intermediate layer (B), directly adhered to the opposite surface of a tie layer (C), comprising high density polyethylene; and two outer layers (A) comprising an ethylene/alpha olefin copolymer.
1. A co-extruded multilayer film for packaging fluid products comprising:
a) a core layer (D) comprising a polyamide;
b) two tie layers (C), directly adhered to the opposite surfaces of the core layer;
c) two intermediate layers (B), directly adhered to the opposite surfaces of the tie layers (C), comprising high density polyethylene; and
d) two outer layers (A) comprising an ethylene/alpha olefin copolymer.
2. The film of claim 1 , wherein the film is characterized by at least one of
a) a haze measured according to ASTM D1003 not higher than 20%,
b) a gloss measured according to ASTM D4257 higher than 90, and
c) a clarity measured according to ASTM D1003 higher than 85%.
3. The film of claim 1 wherein the core layer (D) consists of
a) a single polyamide layer, or
b) three layer sequence consisting of polyamide/barrier/polyamide.
4. The film of claim 1 in which said polyamide is selected from the group consisting of nylon 6, nylon 11, nylon 12, nylon 66, nylon 69, nylon 610, nylon 612, nylon 6/66, amorphous nylon and mixtures thereof.
5. The film of claim 1 , wherein said high density polyethylene is characterized by at least one of
a) a density from about 0.94 to 0.98 g/cm 3 , and
b) a MFR from about 8 to 0.4 g/10 min.
6. The film of claim 1 in which the outer layers (A) comprise admixtures of linear low density polyethylene and low density polyethylene.
7. The film of claim 1 characterized by the following composition:
a) outer layers (A) comprising a total of from 5% to 40% by weight of the overall film weight;
b) polyamide within the core layer (D) comprising a total of from 5 to 30% by weight of the overall film weight;
c) high density polyethylene within the two intermediate layers (B) comprising a total of from 10 to 60% by weight of the overall film weight; and
d) tie layers comprising a total of from 5 to 40% by weight of the overall film weight.
8. The film of claim 1 in which one or more of the layers is cross-linked.
9. A pre-made open pouch made from the film of claim 1 .
10. A package comprising a flowable product and a pouch containing the flowable product, the pouch being made from the film of claim 1 .
11. A process for manufacturing a film comprising the steps of:
a) co-extruding a tubular film comprising a core layer (D) comprising a polyamide, two tie layers (C), directly adhered to the opposite surfaces of the core layer, two intermediate layers (B), directly adhered to the opposite surfaces of the tie layer (C), comprising high density polyethylene, and two outer layers (A) comprising an ethylene/alpha olefin copolymer, through a round die; and
b) quenching said tubular film at a temperature from 5 to 40° C.
12. The process of claim 11 in which said quenching is performed at a temperature from 10 to 30° C.
13. The process of claim 11 further comprising a cross-linking step.