A SHEET-LIKE COMPOSITE, ESPECIALLY FOR CONTAINERS, WITH AN ADHESION-PROMOTING LAYER CHARACTERISED BY DIFFERENT C=O GROUP ABSORPTION MAXIMA

Abstract

The invention relates to a sheet-like composite, comprising as layers of a layer sequence: a) an outer polymer layer, b) a carrying layer following the outer polymer layer, c) a barrier layer following the carrying layer, d) an adhesion-promoting layer following the barrier layer, and e) an inner polymer layer following the adhesion-promoting layer; wherein the adhesion-promoting layer comprises an outer surface of the adhesion-promoting layer and an inner surface of the adhesion-promoting layer; wherein the outer surface of the adhesion-promoting layer i) is adjacent to the barrier layer, and ii) is characterised by a first CO group absorption maximum; wherein the inner surface of the adhesion-promoting layer A) is adjacent to the inner polymer layer, B) is characterised by a second CO group absorption maximum, and C) has a first distance to the outer surface of the adhesion-promoting layer; wherein the first CO group absorption maximum is higher than the second CO group absorption maximum. The invention further relates to a process for manufacturing a sheet-like composite; a sheet-like composite, obtainable by the process; a container precursor; a process for producing a container precursor; a container precursor obtainable by the process; a container; a process for producing a container; a container obtainable by the process; a use of the sheet-like composite; and a use of the container.

Claims

1. A sheet-like composite (100), comprising as layers of a layer sequence: a) an outer polymer layer (101), b) a carrying layer (102) following the outer polymer layer (101), c) a barrier layer (104) following the carrying layer (102), d) an adhesion-promoting layer (105) following the barrier layer (104), and e) an inner polymer layer (106) following the adhesion-promoting layer (105); wherein the adhesion-promoting layer (105) comprises an outer surface (107) of the adhesion-promoting layer and an inner surface (108) of the adhesion-promoting layer; wherein the outer surface (107) of the adhesion-promoting layer i) is adjacent to the barrier layer (104), and ii) is characterised by a first CO group absorption maximum; wherein the inner surface (108) of the adhesion-promoting layer A) is adjacent to the inner polymer layer (106), B) is characterised by a second CO group absorption maximum, and C) has a first distance (109) to the outer surface (107) of the adhesion-promoting layer; wherein the first CO group absorption maximum is higher than the second CO group absorption maximum.

2. The sheet-like composite (100) according to claim 1, wherein the adhesion-promoting layer (105) in a first layer level (201) with a second distance (202) from the outer surface (107) of the adhesion-promoting layer has a third CO group absorption maximum; wherein the second distance (202) amounts to 5 to 95% of the first distance (109); wherein the third CO group absorption maximum a) is lower than the first CO group absorption maximum, and b) is higher than the second CO group absorption maximum.

3. The sheet-like composite (100) according to claim 1, wherein the first CO group absorption maximum is in a range from 0.1 to 5.

4. The sheet-like composite (100) according to claim 1, wherein the second CO group absorption maximum is in a range of more than 0 to 1.

5. The sheet-like composite (100) according to claim 2, wherein the third CO group absorption maximum is in a range from 0.015 to 4.5.

6. The sheet-like composite (100) according to claim 2, wherein the second distance (202) amounts to 5 to 20% of the first distance (109), wherein the third CO group absorption maximum is in a range from 0.05 to 4.5.

7. The sheet-like composite (100) according to claim 2, wherein the second distance (202) amounts to 50 to 95% of the first distance (109), wherein the third CO group absorption maximum is in a range from 0.015 to 1.2.

8. The sheet-like composite (100) according to claim 2, wherein the adhesive layer (105) in a further layer plane (301) with a third distance (302) of the adhesion-promoting layer outer surface (107) a fourth CO group absorption maximum has; wherein the third distance (302) is longer than the second distance (202); wherein the fourth CO group absorption maximum a) is lower than the third CO group absorption maximum, and b) is higher than the second CO group absorption maximum.

9. The sheet-like composite (100) according to claim 1, wherein a CO group absorption maximum of the adhesion-promoting layer (105) along a straight line (501) from the outer surface (107) of the adhesion-promoting layer to the inner surface (108) of the adhesion-promoting layer decreases in at least two stages (500).

10. The sheet-like composite (100) according to claim 1, wherein one selected from the group consisting of the first CO group absorption maximum, the second CO group absorption maximum, the third CO group absorption maximum, and the fourth CO group absorption maximum, or a combination of at least two thereof, is an absorption maximum of CO groups, wherein the CO groups comprise functional groups selected from the group consisting of carboxylic acid groups, a salt of the carboxylic acid groups, carboxylic anhydride groups, or a combination of at least two thereof.

11. The sheet-like composite (100) according to claim 1, wherein one selected from the group consisting of the first CO group absorption maximum, the second CO group absorption maximum, the third CO group absorption maximum, and the fourth CO group absorption maximum, or a combination of at least two thereof is an absorption maximum of a functional group, wherein the functional group is a repeating unit based on a monomer selected from the group consisting of acrylic acid, a salt of acrylic acid, methacrylic acid, a salt of methacrylic acid, an acrylic acid ester, maleic acid, and maleic anhydride, or a combination of at least two thereof.

12. The sheet-like composite (100) according to claim 1, wherein the polymer inner layer (106) contains at least 30 wt.-%, respective to the total weight of the inner polymer layer (106) of a polymer produced by means of a metallocene catalyst.

13. The sheet-like composite (100) according to claim 1, wherein the inner polymer layer (106), is a mixture comprising a polymer produced by means of a metallocene catalyst and an additional polymer.

14. The sheet-like composite (100) according to claim 1, wherein the carrying layer (102) contains one material selected from the group consisting of cardboard, paperboard, and paper, or a combination of at least two thereof.

15. The sheet-like composite (100) according to claim 1, wherein the barrier layer (104) comprises one material selected from the group consisting of a plastic, a metal, and a metal oxide, or a combination of at least two thereof.

16. The sheet-like composite (100) according to claim 1, wherein the carrying layer (102) has at least one hole, where the hole is covered with at least the barrier layer (104) and at least the polymer inner layer (106) as hole covering layers.

17. The sheet-like composite (100) according to claim 1, wherein the first distance (109) is more than one layer thickness of the inner polymer layer (106).

18. The sheet-like composite (100) according to claim 1, wherein the sheet-like composite (100) is rolled up into a coil with at least two layers of the sheet-like composite (100).

19. A process (1000), comprising as process steps (1001, 1002, 1003): a) the provision of a composite precursor, comprising as layers of a layer sequence: i) an outer polymer layer (101), ii) a carrying layer (102) following the outer polymer layer (101), and iii) a barrier layer (104) following the carrying layer (102); b) superimposing an adhesion-promoting layer (105) on the barrier layer (104) on a side facing away from the carrying layer (102); c) superimposing an inner polymer layer (106) on the adhesion-promoting layer (105) on a side facing away from the barrier layer (104); wherein the adhesion-promoting layer (105) comprises an outer surface (107) of the adhesion-promoting layer and an inner surface (108) of the adhesion-promoting layer; wherein the outer surface (107) of the adhesion-promoting layer A) is adjacent to the barrier layer (104), and B) is characterised by a first CO group absorption maximum; wherein the inner surface (108) of the adhesion-promoting layer I) is adjacent to the inner polymer layer (106), II) is characterised by a second CO group absorption maximum, and III) has a first distance (109) to the outer surface (107) of the adhesion-promoting layer; wherein the first CO group absorption maximum is higher than the second CO group absorption maximum.

20. The process (1000) according to claim 19, wherein the adhesion-promoting layer (105) in a first layer level (201) with a second distance (202) from the outer surface (107) of the adhesion-promoting has a third CO group absorption maximum; wherein the second distance (202) amounts to 5 to 95% of the first distance (109); wherein the third CO group absorption maximum a) is lower than the first CO group absorption maximum, and b) is higher than the second CO group absorption maximum.

21. The process (1000) according to claim 19, wherein in process step b) (1002) or in process step c) (1003) or in both, superimposing comprises an extrusion.

22. The process (1000) according to claim 21, wherein the extrusion in process step b) (1002) comprises a co-extrusion of at least a first polymer melt, a second polymer melt, and a third polymer melt; wherein prior to process step b) (1002) the first polymer melt is produced from a first plurality of polymer particles, the second polymer melt is produced from a second plurality of polymer particles, and the third polymer melt is produced from a third plurality of polymer particles; wherein a CO group absorption maximum of the first plurality of polymer particles is higher than a CO group absorption maximum of the third plurality of polymer particles; wherein the CO group absorption maximum of the third plurality of polymer particles is higher than a CO group absorption maximum of the second plurality of polymer particles.

23. A sheet-like composite, obtainable by the method (1000) according to claim 19.

24. A container precursor (800) comprising a sheet-like composite (100) according to claim 1, wherein the sheet-like composite (100) comprises at least one fold (801) with at least two adjoining folding surfaces (802, 803), wherein at least one partial section (804) of the at least two folding surfaces (802, 803) is joined by sealing with the respective other partial section (804).

25. A process (1100), comprising as process steps (1101, 1102, 1103): a) providing the sheet-like composite (100) according to claim 1; b) folding the sheet-like composite (100) to form a fold (801) with at least two adjoining folding surfaces (802, 803); and c) joining at least one partial section (804) of the at least two folding surfaces (802, 803) with the other partial section (804) by a sealing.

26. The process (1100) according to claim 25, wherein at least a part of the sheet-like composite (100) has a temperature in a range of 10 to 50 C. during folding.

27. The process (1100) according to claim 25, wherein the sealing is carried out by one selected from the group consisting of irradiation, contact with a hot solid material, inducing a mechanical vibration, and a contact with a hot gas, or a combination of at least two of them.

28. The process (1100) according to claim 25, wherein the sheet-like composite (100) in process step a) (1101) comprises at least one crease and in process step b) (1102) folding is done along the crease.

29. A container precursor, obtainable by the process (1100) according to claim 24.

30. A closed container (900) surrounding an interior space (901), wherein the container (900) comprises the folded sheet-like composite (100) according to claim 1.

31. A process (1200), comprising as process steps (1201, 1202): a) providing the container precursor (800) according to claim 24; and b) closing the container precursor (800) by means a closing tool.

32. The process (1200) according to claim 30, wherein the container precursor (800) is filled before closing with a food product.

33. A container obtainable by the process according to claim 31.

34. A use of the sheet-like composite (100) according to claim 1, for the production of a container.

35. A use of the container (900) according to claim 30 for filling a food product into the container (900).

Description

[0184] The invention is illustrated in more detail below in examples and drawings, whereby the examples and drawings do not imply a limitation of the invention. Shown are:

[0185] FIG. 1 a schematic cross-section through a layer sequence of a sheet-like composite according to the invention;

[0186] FIG. 2 a schematic cross-section through a layer sequence of a further sheet-like composite according to the invention;

[0187] FIG. 3 a schematic cross-section through a layer sequence of a further sheet-like composite according to the invention;

[0188] FIG. 4 Measurement results of CO group absorption maximums of an adhesion-promoting layer according to the invention as a function of the distance between the measuring position to the outer surface of the adhesion-promoting layer;

[0189] FIG. 5a) a schematic step function of the CO group absorption maxima of an adhesion-promoting layer according to the invention from a position on a straight line from the outer surface of the adhesion-promoting layer to the inner surface of the adhesion-promoting layer;

[0190] FIG. 5b) a schematic cross-section through a layer sequence of a sheet-like composite according to the invention with a straight line along which the CO group absorption maxima depicted in FIG. 5a) can be measured;

[0191] FIG. 6 a schematic step function of the CO group absorption maxima of an additional adhesion-promoting layer according to the invention at a distance from the outer surface of the adhesion-promoting layer;

[0192] FIG. 7 ATR-IR spectrums of various polymers;

[0193] FIG. 8 a schematic representation of a container precursor according to the invention;

[0194] FIG. 9 a schematic representation of a container according to the invention;

[0195] FIG. 10 a flow chart of a process for manufacturing a sheet-like composite according to the invention;

[0196] FIG. 11 a flow chart of a process for manufacturing a container precursor according to the invention;

[0197] FIG. 12 a flow chart of a process for manufacturing a container according to the invention; and

[0198] FIG. 13 a flow chart of a further method for manufacturing a container according to the invention.

[0199] FIG. 1 shows a schematic cross-section through a layer sequence of a sheet-like composite 100 according to the invention The sheet-like composite 100 comprises an outer polymer layer 101 as layers of a layer sequence, followed by a carrying layer 102, followed by a polyethylene layer 103, followed by a barrier layer 104, followed by an adhesion-promoting layer 105, followed by an inner polymer layer 106 The adhesion-promoting layer 105 comprises an outer surface of the adhesion-promoting layer 107 and an inner surface of the adhesion-promoting layer 108. The outer surface 107 of the adhesion-promoting layer is adjacent to the barrier layer 104 and is characterised by a first CO group absorption maximum. The inner surface 108 of the adhesion-promoting layer is adjacent to the inner polymer layer 106 and is characterised by a second CO group absorption maximum. Furthermore, the inner surface 108 of the adhesion-promoting layer has a first distance 109 to the outer surface 107 of the adhesion-promoting layer. The first distance 109 amounts to 100 m. The first CO group absorption maximum amounts to 1.7. The second CO group absorption maximum amounts to 0.22. The outer polymer layer 101 is composed to 100 wt.-% respective to the outer polymer layer 101 of an LDPE and features a surface weight of 20 g/m.sup.2. The carrying layer 102 has a surface weight of 210 g/m.sup.2 and consists of the Liquid Packaging Board Stora Enso Natura T duplex from the Stora Enso AG company. The carrying layer 102 is characterised by a double coating, a Scott Bond value of 200 J/m.sup.2 and a residual moisture content of 7.5%. The polyethylene layer 103 is characterised by a surface weight of 22 g/m.sup.2 and consists of an LDPE. Another layer may be located between the polyethylene layer 103 and the barrier layer 104 (not shown), which consists to 100% weight of Novex M21N430 from Ineos Kln GmbH and features a surface weight of 3 g/m.sup.2. The barrier layer 104 has a layer thickness of 6 m and consists of aluminium EN AW 8079 from Hydro Aluminium Deutschland GmbH. The adhesion-promoting layer 105 has a surface weight of 90 g/m.sup.2, a layer thickness of 100 m, and consists of 50 wt.-% each respective to the total weight of the adhesion-promoting layer 105 of Escor 5100 from the Exxon Mobil Corporation and Novex M21N430 from Ineos Kln GmbH. The adhesion-promoting layer 105 was produced via co-extrusion. For this purpose, a polymer melt of Escor 5100 and a polymer melt of Novex M21N430 were created initially. The two polymer melts were brought together and put in contact in a feed block. The contacted polymer melts were extruded together onto the barrier layer 104. Thus, when manufacturing the adhesion-promoting layer 105, it came to a partial mixing of the melting of Escor 5100 and Novex M21N430 in a transition section. Outside of the transition section, the adhesion-promoting layer 105 in a part facing the barrier layer 104 consists mainly of Escor 5100 and in a part facing the inner polymer layer 106 part mainly of Novex M21N430. The inner polymer layer 106 has a surface weight of 22 g/m.sup.2, a layer thickness of 10 m and consists of a PE blend. The PE blend comprises about 80 wt.-% of an mLDPE and 20 wt.-% of an LDPE, respective to the PE blend.

[0200] FIG. 2 shows a schematic cross-section through a layer sequence of a further sheet-like composite 100 according to the invention. The sheet-like composite 100 of FIG. 2 is the sheet-like composite 100 of FIG. 1, but with a different adhesion-promoting layer 105. The adhesion-promoting layer 105 comprises an outer surface of the adhesion-promoting layer 107 and an inner surface of the adhesion-promoting layer 108. The outer surface 107 of the adhesion-promoting layer is adjacent to the barrier layer 104 and is characterised by a first CO group absorption maximum. The inner surface 108 of the adhesion-promoting layer is adjacent to the inner polymer layer 106 and is characterised by a second CO group absorption maximum. Furthermore, the inner surface 108 of the adhesion-promoting layer has a first distance 109 to the outer surface 107 of the adhesion-promoting layer. The first distance 109 amounts to 100 nm. The first CO group absorption maximum amounts to 1.7. The second CO group absorption maximum amounts to 0.22. The adhesion-promoting layer 105 is further characterised in that it features a third level CO group absorption maximum at first layer level 201 with a second distance 202 of 50 m from the outer surface 107 of the adhesion-promoting layer. The third CO group absorption maximum amounts to 0.9. The adhesion-promoting layer 105 has a surface weight of 90 g/m.sup.2 and consists of 33.3 wt.-% each respective to the total weight of the adhesion-promoting layer 105 of Escor 5100 from Exxon Mobil Corporation; Escor 6000 from Exxon Mobil Corporation; and Novex M21N430 from Ineos Kln GmbH. The adhesion-promoting layer 105 was produced by co-extrusion. For this purpose, a polymer melt of Escor 5100 and a polymer melt of Escor 6000 and a polymer melt of Novex M21N430 were created initially. The three polymer melts were brought together and put in contact in a feed block. The contacted polymer melts were extruded together onto the barrier layer 104. Thus, when manufacturing the adhesion-promoting layer 105, it came to a partial mixing of the melting of Escor 5100 and Escor 6000 in a transition area; and the melting of Escor 6000 and Novex M21N430 in another transition area. Outside the transition areas, the adhesion-promoting layer 105 consists mainly of a part facing the barrier layer 104 of Escor 5100; in a central part mainly of Escor 6000; and in a part facing the inner polymer layer 106 mainly of Novex M21N430.

[0201] FIG. 3 shows a schematic cross-section through a layer sequence of a further sheet-like composite 100 according to the invention. The sheet-like composite 100 of FIG. 3 is the sheet-like composite 100 of FIG. 1, but with a different adhesion-promoting layer 105. The adhesion-promoting layer 105 comprises an outer surface of the adhesion-promoting layer 107 and an inner surface of the adhesion-promoting layer 108. The outer surface 107 of the adhesion-promoting layer is adjacent to the barrier layer 104 and is characterised by a first CO group absorption maximum. The inner surface 108 of the adhesion-promoting layer is adjacent to the inner polymer layer 106 and is characterised by a second CO group absorption maximum. Furthermore, the inner surface 108 of the adhesion-promoting layer has a first distance 109 to the outer surface 107 of the adhesion-promoting layer. The first distance 109 amounts to 100 m. The first CO group absorption maximum amounts to 1.9. The second CO group absorption maximum amounts to 0.2. The adhesion-promoting layer 105 is further characterised in that it features a third level CO group absorption maximum at first layer level 201 with a second distance 202 of 25 m from the outer surface 107 of the adhesion-promoting layer. The third CO group absorption maximum amounts to 0.9. The adhesion-promoting layer 105 is further characterised in that it features a fourth CO group absorption maximum in a further layer level 301 with a third distance 302 of 75 m from the outer surface 107 of the adhesion-promoting layer. The fourth CO group absorption maximum amounts to 0.5. The adhesion-promoting layer 105 has a surface weight of 100 g/m.sup.2 and consists of 25 wt.-% each respective to the total weight of the adhesion-promoting layer 105 of Escor 5100 from Exxon Mobil Corporation; of Escor 6000 from Exxon Mobile Corporation; of Novex M23N430 from Ineos Kln GmbH; and of Novex M21N430 from Ineos Kln GmbH. The adhesion-promoting layer 105 was produced by co-extrusion. For this purpose, a polymer melt of each Escor 5100, Escor 6000, Novex M23N430 and Novex M21N430 was first produced. The four polymer melts were brought together and put in contact in a feed block. The contacted polymer melts were extruded together onto the barrier layer 104. Thus, when manufacturing the adhesion-promoting layer 105, it came to a partial mixing of the melting of Escor 5100 and Escor 6000 in a transition area; and the melting of Escor 6000 and Novex M23N430 in a second transition area; and the melting of Novex M23N430 and Novex M21N430 in a third transition area. Outside of the transition areas, the adhesion-promoting layer 105 consists mainly of a part facing the barrier layer 104 of Escor 5100; in a part following the inner part 108 of the adhesion-promoting layer, mainly of Novex M23N430; and in a part facing the inner polymer layer 106, mainly of Novex M21N430.

[0202] FIG. 4 shows measurement results of CO group absorption maximums of an adhesion-promoting layer 105, according to the invention, derived from a distance of the measuring position to the outer surface 107 of the adhesion-promoting layer. The measurement position at distance 0 is located on the outer surface 107 of the adhesion-promoting layer. The measurement position at a distance of 100 nm is on an inner surface 108 of the adhesion-promoting surface. FIG. 4 shows that the CO group absorption maximum of the outer surface 107 of the adhesion-promoting layer to the inner surface 108 of the adhesion-promoting layer becomes lower within the adhesion-promoting layer 105.

[0203] FIG. 5a) shows a schematic step function of CO group absorption maximums of an adhesion-promoting layer 105, according to the invention, from a position on a straight line 501 from the outer surface 107 of the adhesion-promoting layer to the inner surface 108 of the adhesion-promoting layer. The position 0 corresponds to the outer side 107 of the adhesion-promoting layer. The dotted line in FIG. 5a) marks the location corresponding to the inner surface 108 of the adhesion-promoting layer. The step function comprises 3 steps 500 and is monotonically decreasing, but not strictly monotonically decreasing. On the first step 500 (first from the left) is the first CO group absorption maximum. Below the third step 500 (value at the position of the inner surface of the adhesion-promoting layer) is the second CO group absorption maximum. On the second step 500 (second from the left) is the third CO group absorption maximum. On the third step 500 (third from the left) is the fourth CO group absorption maximum. The values shown in FIG. 5a) belong to the adhesion-promoting layer 105 of the sheet-like composite 100 in FIG. 5b).

[0204] FIG. 5b) shows a schematic cross-section through a layer sequence of a sheet-like composite 100 according to the invention with a line 501 along which the CO group absorption maximums shown in FIG. 5a) can be measured. The outer polymer layer 101, the carrying layer 102, the polyethylene layer 103, the barrier layer 104 and the inner polymer layer 106 are similar to those described in FIG. 1. The adhesion-promoting layer 105 is composed of 4 different ethylene-acrylic acid co-polymers (EAA). To produce the adhesion-promoting layer 105, 4 different EAA co-polymer melts were co-extruded. In this case, the acrylic acid content decreases from a first co-polymer melt over a second and third to a fourth co-polymer melt.

[0205] FIG. 6 shows a schematic step function of the CO group absorption maximums of a further adhesion-promoting layer 105 according to the invention of a distance to the outer surface 107 of the adhesion-promoting layer 107. The distance 0 corresponds to the outer surface 107 of the adhesion-promoting layer. The dotted line in FIG. 6 marks the distance corresponding to the inner surface 108 of the adhesion-promoting layer. The step function comprises 4 steps 500 and is monotonically decreasing, but not strictly monotonically decreasing. The adhesion-promoting layer 105 is composed of 5 different ethylene-methacrylic acid co-polymers (EMAA). To produce the adhesion-promoting layer 105, 5 different EAA copolymer melts were coextruded. In this case, the methacrylic acid content decreases from a first co-polymer melt over a second, third, and fourth to a fifth co-polymer melt.

[0206] FIG. 7 shows ATR-IR spectrums of various polymers. For the various co-polymers (with ethylene acrylic acid (EAA) and ethylene methacrylic acid (EMAA) as co-monomers), the acrylic acid or methacrylic acid contents are shown between parentheses. The spectrums shown were measured on the pure co-polymers, not on the adhesion-promoting layer 105, according to the invention. FIG. 7 is merely illustrative of the ATR-infrared spectroscopy. The measurement was performed in a wave number range from 2000 to 1000 cm.sup.1 with a resolution of 4 cm.sup.1. The peaks in the wave number range 1750-1650 cm.sup.1 are generated by the oscillation of CO groups. In addition, FIG. 7 includes another group of peaks in the wave number range from 1400 to 1500 cm.sup.1. These additional peaks correspond to the CH.sub.2 oscillation. The CO group absorption maximum of each spectrum is determined as the ratio of the peak height in the wave number range from 1750 to 1650 cm.sup.1 to the peak height in the wave number range from 1400 to 1500 cm.sup.1. The CO oscillation is thus standardised on the same spectrum as the CH.sub.2 oscillation. This standardised CO oscillation is the dimensionless CO group absorption maximum to be determined. As can be seen, the peak heights differ in the wavelength range from 1750 to 1650 cm.sup.1 between the various co-polymers, while the peak heights in the wavelength range from 1400 to 1500 cm.sup.1 are roughly constant.

[0207] FIG. 8 shows a schematic representation of a container precursor 800 according to the invention. The container precursor 800 comprises the sheet-like composite 100 of FIG. 1. Furthermore, the container precursor 800 comprises a fold 801 with an adjacent first folding surface 802 and a second folding surface 803. The first folding surface 802 and the second folding surface 803 overlap each other and are joined to each other by means of sealing in a sealing section 804. The sealing section 804 represents a longitudinal seam of the container precursor 800. The container precursor 800 in FIG. 8 is shell-shaped.

[0208] FIG. 9 shows a schematic representation of a container 900 according to the invention. The container 900 is closed and encloses an interior space 901, which contains cashew apple juice as the food product. The container 900 comprises the sheet-like composite as a wall, according to FIG. 2.

[0209] FIG. 10 shows a flow chart of process 1000 according to the invention for the production of a sheet-like composite 100. The process 1000 comprises a step a) 1001 providing a composite precursor, comprising as layers a layer sequence:

[0210] an outer polymer layer 101, a carrying layer 102 following the outer polymer layer 101, a polyethylene layer 103 following the carrying layer, a further polymer layer following the polyethylene layer and a barrier layer 104 following the further polymer layer. The outer polymer layer 101 is composed of 100 wt.-% respective to the outer polymer layer 101 of an LDPE and features a surface weight of 20 g/m.sup.2. The carrying layer 102 features a surface weight of 210 g/m.sup.2 and consists of the Liquid Packaging Board Stora Enso Natura T duplex from the company Stora Enso AG. The carrying layer 102 is characterised by a double coating, a Scott Bond value of 200 J/m.sup.2 and a residual moisture content of 7.5%. The polyethylene layer 103 is characterised by a surface weight of 22 g/m.sup.2 and consists of an LDPE. The further polymer layer consists of 100 wt.-% respective to the further polymer layer of Novex M21N430 from Ineos Kln GmbH and features a surface weight of 3 g/m.sup.2. The barrier layer 104 has a layer thickness of 6 m and consists of aluminium EN AW 8079 from Hydro Aluminium Deutschland GmbH. In a process step b) 1002 of the process 1000, the barrier layer 104 is overlaid by an adhesion-promoting layer 105 on a side facing away from the carrying layer 102. This is done by co-extrusion of 3 ethylene-acrylic acid or ethylene-methacrylic acid co-polymers of different acrylic acid or methacrylic acid content. The 3 ethylene-acrylic acid co-polymers are Escor 5100 from Exxon Mobil Corporation; Escor 6000 from Exxon Mobile Corporation; and Novex M21N430 from Ineos Kln GmbH. The application of the adhesion-promoting layer 105 to the barrier layer 104 is made by co-extruding melts of the 3 aforementioned co-polymers. In a process step c) 1003 the adhesion-promoting layer 105 is overlaid by extrusion by an inner polymer layer 106 on a side facing away from the barrier layer 104. The inner polymer layer 106 features a surface weight of 10 g/m.sup.2, a layer thickness of 10 m, and consists of a PE blend. The PE blend comprises 70 wt.-% of an mLDPE and 30% weigh of an LDPE, each respective to the PE blend. Thus, an adhesion-promoting layer 105 is obtained, which comprises an outer surface 107 of the adhesion-promoting layer and an inner surface 108 of the adhesion-promoting layer. The outer surface 107 of the adhesion-promoting layer is adjacent to the barrier layer 104 and is characterised by a first CO group absorption maximum. The inner surface 108 of the adhesion-promoting layer is adjacent to the inner polymer layer 106 and is characterised by a second CO group absorption maximum. Furthermore, the inner surface 108 of the adhesion-promoting layer has a first distance 109 to the outer surface 107 of the adhesion-promoting layer. The first distance 109 amounts to 100 m. The first CO group absorption maximum amounts to 1.7. The second CO group absorption maximum amounts to 0.2. The adhesion-promoting layer 105 is further characterised in that it features a third level CO group absorption maximum at first layer level 201 with a second distance 202 of 50 m from the outer surface 107 of the adhesion-promoting layer. The third CO group absorption maximum amounts to 0.9. The adhesion-promoting layer 105 has a surface weight of 90 g/m.sup.2.

[0211] FIG. 11 shows a flow chart of a process 100 of the invention for manufacturing a container precursor 800. Process 1100 comprises a process step a) 1101: providing a sheet-like composite 100 according to FIG. 1; a process step b) 1102: folding the sheet-like composite 100 to form a fold 801 with at least two adjoining folding surfaces 802 and 803; and a process step c) 1103: joining at least a partial section 804 of the at least two folding surfaces 802, 803 with the other partial section 804 by sealing. In process step c) 1103, the longitudinal seam of the container precursor 800 is formed. The folding in step b) 1102 is carried out as cold-folding and sealing in step c) is carried out by heat-sealing via ultrasound transmitted through a sonotrode.

[0212] FIG. 12 shows a flow chart of a process 1200 according to the invention for producing a container 900 according to FIG. 9. The method 1200 comprises a process step a) 1201: Provision of a container precursor 800. The container precursor 800 comprises the sheet-like composite 100 of FIG. 2. Furthermore, the container precursor 800 comprises a fold 801 with adjoining folding surfaces 802 and 803. The two folding surfaces 802, 803 adjacent at fold 801 overlap in a sealing section 804. In the sealing section 804, there is a sealing connection between the two folding surfaces 802 and 803. The container precursor is tube-shaped. In a process step b) 1202 of the process 1200, the container precursor 800 is closed by means of a closing tool. For this purpose, the container precursor 800 is laterally compressed, fixed and a part of the tube-shaped container precursor 800 is separated in the direction of the tube. This part obtains a bottom section by means of fold forming and sealing or gluing, which is closed. This creates an open container. The open container obtains a top section by means of fold forming and sealing or gluing, which is closed to obtain the closed container 900.

[0213] FIG. 13 shows a flow chart of a further process 1200 for producing a container 900, according to the invention. The process 1200 in FIG. 13 is the process in FIG. 12, wherein the process in FIG. 13 comprises a further process step 1301 between the process steps a) 1201 and b) 1202. In the further process step 1301, a food product, a ham broth, is filled into the container precursor 800. The filling is carried out before the separation of the part of the tube-shaped container precursor 800.

LIST OF REFERENCE NUMBERS

[0214] 100 sheet-like composite according to the invention [0215] 101 outer polymer layer [0216] 102 carrying layer [0217] 103 polyethylene layer [0218] 104 barrier layer [0219] 105 adhesion-promoting layer [0220] 106 inner polymer layer [0221] 107 outer surface of the adhesion-promoting layer [0222] 108 inner surface of the adhesion-promoting layer [0223] 109 first distance [0224] 201 first layer level [0225] 202 second distance [0226] 301 additional layer level [0227] 302 third distance [0228] 500 level [0229] 501 straight line from the outer surface of the adhesion-promoting layer to the inner surface of the adhesion promoting layer [0230] 800 container precursor according to the invention [0231] 801 fold [0232] 802 first folding surface [0233] 803 second folding surface [0234] 804 sealing section [0235] 900 closed container according to the invention [0236] 901 interior space [0237] 1000 process for manufacturing a sheet-like composite according to the invention [0238] 1001 process step a) of the process for manufacturing a sheet-like composite [0239] 1002 process step b) of the process for manufacturing a sheet-like composite [0240] 1003 process step c) of the process for manufacturing a sheet-like composite [0241] 1100 process for manufacturing a container precursor according to the invention [0242] 1101 process step a) of the process for producing a container precursor [0243] 1102 process step b) of the process for producing a container precursor [0244] 1103 process step c) of the process for manufacturing a container precursor [0245] 1200 process for producing a container according to the invention [0246] 1201 process step a) of the process for producing a container [0247] 1202 process step b) of the process for producing a container [0248] 1301 process step for filling with a food product