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1. WO2020109403 - ENHANCED PVOH-BASED BARRIER LAYER COMPOSITION, BARRIER LAYER AND METHODS FOR ITS MANUFACTURE

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[ EN ]

Claims

1. A packaging material comprising a fibre based substrate and a gas barrier layer based on a polyvinyl alcohol (PVOH), wherein said gas barrier layer comprises an interpolymer complex forming agent (IPCFA), which IPCFA is a water-soluble polymer exhibiting functional groups capable of forming hydrogen bonds with -OFI groups of the PVOFI, characterized in that said PVOFI has a weight average molecular weight (Mw) measured according to ASTM D4001 - 13 in the range of 80 kg/mol to 135 kg/mol, the proportion of said IPCFA to PVOFI in said gas barrier layer is in the range of 0.5 to 7.0 % (w/w) and said packaging material has an oxygen permeability (OP) below 14 ml pm/m2 day atm, which OP is obtained by

multiplying the oxygen transmission rate (OTR) of the packaging material measured according to ASTM F1927-7 at a relative humidity (RFI) of 80% and 23 °C by the thickness of the gas barrier layer.

2. The packaging material according to claim 1 , wherein said IPCFA has a weight average molecular weight (Mw) in the interval of 10 kg/mol to 1500 kg/mol, such as 25 kg/mol to 1500 kg/mol or 10 kg/mol to 1000 kg/mol, preferably in the interval of 30 kg/mol to 700 kg/mol, more preferably in the interval of 50 kg/mol to 500 kg/mol and most preferably in the interval of 100 kg/mol to 700 kg/mol, such as 200 kg/mol to 700 kg/mol.

3. The packaging material according to claim 1 or 2, wherein said IPCFA is chosen from polyacrylic acid, polyvinyl pyrrolidone, and non-ionic polyacrylamide.

4. The packaging material according to any one of the preceding claims, wherein the proportion of said IPCFA to PVOFI in the coating composition is in the interval of 0.5 to 6 % (w/w), such as 1 to 5 % (w/w), such as 1 to 4 % (w/w).

5. The packaging material according to any one of the preceding claims, wherein said fibre based substrate is a paper or paper board comprising at least one fibre based layer.

6. The packaging material according to any one of the preceding claims, wherein said packaging material has an oxygen transmission rate (OTR) in the interval 0.1 to 3 ml/m2 day atm, measured according to ASTM F1927 - 07and at a relative humidity (RFI) of 50 % and 23 °C.

7. The packaging material according to any one of the preceding claims, wherein said packaging material has an oxygen transmission rate (OTR) in the interval of 0.5 to 3 ml/m2 day atm, measured according to ASTM F1927 - 07and at a relative humidity (RH) of 80 % and 23 °C.

8. A method for the production of a packaging material according to anyone of claims 1 -7, wherein a coating composition comprising said PVOH and said IPCFA dissolved in a first solvent is provided, and said coating composition is applied onto said substrate to form said PVOFI-based gas barrier layer.

9. The method according to claim 8, wherein the formation of said PVOFI-based gas barrier layer comprises drying the applied coating composition at a temperature below the boiling point of said first solvent.

10. The method according to claim 8 or 9, wherein the formation of said PVOFI-based gas barrier layer comprises drying the applied coating composition and heating the dried coating composition.

11. The method according to any one of claims 8-10, wherein said PVOFI-based layer, after it has been dried and optionally heated, is crosslinked by

contacting it with a crosslinking agent to achieve crosslinking of the polymers.