Sheet-like composite for producing dimensionally stable food product containers with a barrier layer comprising a barrier substrate layer and an inwards-pointing barrier material layer
The present invention relates to a sheet-like composite comprising as layers of a layer sequence in a direction from an outer side of the sheet-like composite to an inner side of the sheet-like composite a) a carrier layer, and b) a barrier layer comprising i) a barrier substrate layer, and ii) a barrier material layer; wherein the barrier material layer has a thickness in a range from 1 nm to 1 μm; wherein the barrier material layer overlies the barrier substrate layer on a layer surface of the barrier substrate layer that faces the inner side. The invention further relates to methods for producing a sheet-like composite, a container precursor and a closed container, and also to the aforesaid method products; to a further container precursor; to a further closed container; and to a use of the sheet-like composite.
1. A sheet-like composite comprising as layers of a layer sequence in a direction from an outer side of the sheet-like composite to an inner side of the sheet-like composite
a) a carrier layer, and
b) a barrier layer comprising
i) a barrier substrate layer, and
ii) a barrier material layer;
wherein the barrier material layer has a thickness in a range from 1 nm to 800 nm;
wherein any barrier material layer having a thickness in a range from 1 nm to 800 nm overlies the barrier substrate layer only on a layer surface of the barrier substrate layer that faces the inner side,
wherein the barrier material layer comprises a barrier material to an extent of at least 60% by weight, based on the weight of the barrier material layer,
wherein the barrier material is an elemental metal; and
wherein the barrier layer has at least one of the following features:
a. an oxygen permeation rate in a range from 0.1 to 40 cm 3 /(m 2 · d · bar); and
b. a water vapour permeation rate in a range from 0.1 to 40 g/(m 2 ·d).
2. The sheet-like composite according to claim 1 , wherein the barrier layer has a thickness in a range from 2 to 35 μm.
3. The sheet-like composite according to claim 1 , wherein the barrier substrate layer adjoins the barrier material layer.
4. The sheet-like composite according to claim 1 , wherein the barrier substrate layer comprises a polymer to an extent of at least 50% by weight, based on the weight of the barrier substrate layer, the polymer being selected from the group consisting of a polycondensate, a polypropylene, a polyvinyl alcohol, or a combination of at least two thereof.
5. The sheet-like composite according to claim 1 , wherein the sheet-like composite contains a linear depression on the outer side.
6. The sheet-like composite according to claim 1 , wherein the barrier layer is characterized by an aluminium content of less than 50% by weight, based on the weight of the barrier layer.
7. The sheet-like composite according to claim 1 , wherein a layer surface of the barrier layer that faces the inner side of the sheet-like composite adjoins a first adhesion promoter layer, the first adhesion promoter layer comprising an acrylic acid copolymer.
8. The sheet-like composite according to claim 1 , wherein a layer surface of the barrier layer that faces the outer side of the sheet-like composite adjoins a further adhesion promoter layer, the further adhesion promoter layer comprising an ethylene-alkyl acrylate copolymer.
9. The sheet-like composite according to claim 1 , wherein the sheet-like composite further comprises an outer polymer layer,
the outer polymer layer
overlying the carrier layer on a side of the carrier layer that faces the outer side of the sheet-like composite, and
comprising an LDPE to an extent of at least 50% by weight, based on the weight of the outer polymer layer.
10. The sheet-like composite according to claim 1 , wherein the sheet-like composite further comprises an inner polymer layer,
the inner polymer layer overlying the barrier layer on a side of the barrier layer that faces the inner side of the sheet-like composite.
11. The sheet-like composite according to claim 1 , wherein the sheet-like composite further comprises an intermediate polymer layer between the carrier layer and the barrier layer,
wherein the intermediate polymer layer comprises an LDPE to an extent of at least 50% by weight, based on the weight of the intermediate polymer layer.
12. The sheet-like composite according to claim 1 , wherein the sheet-like composite further comprises an intermediate polyolefin layer between the carrier layer and the barrier layer.
13. The sheet-like composite according to claim 1 , wherein the barrier substrate layer comprises a biaxially oriented polymer.
14. The sheet-like composite according to claim 1 , wherein the carrier layer contains one selected from the group consisting of cardboard, paper board and paper, or a combination of at least two thereof.
15. A method for producing the sheet-like composite according to claim 1 , the method comprising as method steps
a) providing
i) a sheet-like composite precursor, containing the carrier layer, and
ii) the barrier layer; and
b) overlaying the carrier layer with the barrier layer, thereby obtaining the sheet-like composite;
wherein, during the overlaying in method step b), the barrier material layer is located on a side of the barrier substrate layer that faces away from the carrier layer.
16. The method according to claim 15 , wherein the barrier layer has a thickness in a range from 2 to 35 μm.
17. The method according to claim 15 , wherein the barrier substrate layer adjoins.
18. The method according to claim 15 , wherein the barrier substrate layer comprises a polymer to an extent of at least 50% by weight, based on the weight of the barrier substrate layer, the polymer being selected from the group consisting of a polycondensate, a polypropylene, a polyvinyl alcohol, or a combination of at least two thereof.
19. The method according to claim 15 , wherein the method further comprises a method step
c) contacting a layer surface of the barrier layer that faces away from the carrier layer with a first adhesion promoter composition, thereby obtaining a first adhesion promoter layer,
the first adhesion promoter composition comprising an acrylic acid copolymer.
20. The method according to claim 15 , wherein the method further comprises a method step
d) overlaying the barrier layer on a side of the barrier layer that faces away from the carrier layer with an inner polymer composition, thereby obtaining an inner polymer layer.
21. The method according to claim 15 , wherein the barrier layer is characterized by an aluminium content of less than 50% by weight, based on the weight of the barrier layer.
22. A method, comprising as method steps
A. providing the sheet-like composite according to claim 1 , comprising a first longitudinal edge and a further longitudinal edge;
B. folding the sheet-like composite; and
C. contacting the first longitudinal edge with the further longitudinal edge and joining the first longitudinal edge to the further longitudinal edge, thereby obtaining a longitudinal seam.
23. A method, comprising as method steps
i. providing a container precursor comprising a sheet-like composite according to claim 1 ;
ii. forming a base region of the container precursor by folding the sheet-like composite;
iii. closing the base region;
iv. filling the container precursor with a food product, and
v. closing the container precursor in a head region, thereby obtaining a closed container.