Printed packaging laminate, method for manufacturing of the packaging laminate and packaging container
A laminated packaging material for food packaging, comprises a core layer of paper or paperboard, which on a first side intended to be directed towards the outside of a packaging container, has, in the following order, a dry pre-coating for receiving a printed décor of an aqueous, pigment-based, ink-jet printing ink, a pigment-based ink-jet printed ink décor layer and further laminated onto the printed décor layer, a protective outermost layer of a thermoplastic polymer. Also disclosed is a method for manufacturing of the packaging laminate and to a packaging container that is made from the laminated packaging material as well as to a pre-coating composition for use in the laminated packaging material and in the manufacturing thereof.
1. A laminated packaging material for food packaging, comprising a substrate layer, which on the substrate surface of its first side, intended to be directed towards the outside of a packaging container made from the packaging material, has applied to it, in the following order, a pre-coating for receiving a printed décor layer of an aqueous pigment-based ink-jet printing ink, a pigment-based ink-jet printed décor layer and further laminated onto the printed décor layer, an outermost layer of a thermoplastic polymer, the pre-coating composition comprising:
an aqueous soluble multivalent cation salt and a polymer binder in which the applied salt concentration at the substrate surface is from 0.02 g/m 2 to 0.05 g/m 2 dry coating weight, and the weight ratio of the multivalent cation salt to the polymer binder is 1:10 to 2:5 calculated on solid matter;
the pre-coating composition is applied onto the substrate surface at from 0.1 g/m 2 to 0.5 g/m 2 total dry coating weight; and
the multivalent cation salt is CaCl 2 .
2. Laminated packaging material according to claim 1 , wherein the polymer binder is a hydrophilic polymer.
3. Laminated packaging material according to claim 1 , wherein the weight ratio of the multivalent cation salt to the polymer binder is 1:5 to 2:5 calculated on solid matter.
4. Laminated packaging material according to claim 1 , wherein the pre-coating composition is applied onto the substrate surface at from 0.1 g/m 2 to 0.3 g/m 2 .
5. Laminated packaging material according to claim 1 , wherein the polymer binder is a polymer selected from the group consisting of polyvinyl alcohol (PVOH) or modified polyvinylalcohol, water dispersible ethylene vinyl alcohol (EVOH), polysaccharides, including cellulose, cellulose derivatives, CMC, starch and starch derivatives, acrylic-based (co-)polymers and combinations of two or more thereof.
6. Laminated packaging material according to claim 1 , wherein the polymer binder is crosslinked.
7. Laminated packaging material according to claim 1 , wherein the substrate is a paper or paperboard constituting a core layer of the laminated packaging material.
8. Laminated packaging material according to claim 1 , wherein the substrate layer is further laminated to an innermost layer of a thermoplastic polymer on its second side, which is intended to be directed towards the inside of a packaging container.
9. Laminated packaging material according to claim 8 , further comprising a gas barrier layer between the substrate layer and the innermost layer.
10. Laminated packaging material according to claim 1 , wherein the polymer binder comprises a cross-linked aceto-acetylated polyvinyl alcohol.
11. Laminated packaging material according to claim 1 , wherein the polymer binder comprises a polyvinyl alcohol having a saponification degree of from 79% to 99.99%.
12. Laminated packaging material according to claim 1 , wherein the polymer binder is cross-linked with a dialdehyde compound, preferably glyoxal.
13. Laminated packaging material according to claim 1 , wherein the polymer binder is cross-linked with glyoxal.
14. Laminated packaging material according to claim 1 , wherein the ink-jet ink is an aqueous pigment-based ink.
15. A laminated packaging material for food packaging, comprising a substrate layer, which on the substrate surface of its first side, intended to be directed towards the outside of a packaging container made from the packaging material, has applied to it, in the following order, a pre-coating for receiving a printed décor layer of an aqueous pigment-based ink-jet printing ink, a pigment-based ink-jet printed décor layer and further laminated onto the printed décor layer, an outermost layer of a thermoplastic polymer, the pre-coating composition comprising:
an aqueous soluble multivalent cation salt and a polymer binder in which the applied salt concentration at the substrate surface is from 0.02 g/m 2 to 0.05 g/m 2 dry coating weight, and the weight ratio of the multivalent cation salt to the polymer binder is 1:10 to 2:5 calculated on solid matter;
the pre-coating composition is applied onto the substrate surface at from 0.1 g/m 2 to 0.5 g/m 2 total dry coating weight;
the multivalent cation salt is calcium, magnesium or aluminium salt with a chloride or acetate counter ion; and
the concentration of the multivalent cation salt is at a calcium ion equivalent to from 0.02 g/m 2 to 0.1 g/m 2 of calcium chloride.
16. Method of manufacturing a laminated packaging material comprising:
continuously applying a pre-coating composition onto a substrate surface of a moving substrate to produce a pre-coated substrate web, the pre-coating composition being comprised of an aqueous soluble multivalent cation salt and a polymer binder in which the applied salt concentration at the substrate surface is from 0.02 g/m 2 to 0.05 g/m 2 dry coating weight, and the weight ratio of the multivalent cation salt to the polymer binder is 1:10 to 2:5 calculated on solid matter;
transporting the pre-coated substrate web through a drying station to at least partially dry the applied pre-coating composition by evaporating off water;
printing an aqueous pigment-based ink-jet décor layer onto the pre-coated substrate surface after transporting the pre-coated substrate web through the drying station to produce a pre-coated and printed substrate web;
transporting the pre-coated and printed substrate web through a drying station to evaporate off water from the printed décor layer; and
applying a layer of a thermoplastic polymer onto the pre-coated and printed substrate web after transporting the pre-coated and printed substrate web through the drying station.
17. Method according to claim 16 , wherein the polymer binder is a hydrophilic polymer.
18. Method according to claim 16 , wherein the weight ratio of the multivalent cation salt to the polymer binder is 1:5 to 2:5 calculated on solid matter.
19. Method according to claim 16 , wherein the pre-coating composition is applied onto the substrate surface at from 0.1 g/m 2 to 0.3 g/m 2 .
20. Method according to claim 16 , wherein the polymer binder is a polymer selected from the group consisting of polyvinyl alcohol (PVOH) or modified polyvinylalcohol, water dispersible ethylene vinyl alcohol (EVOH), polysaccharides, including cellulose, cellulose derivatives, CMC, starch and starch derivatives, acrylic-based (co-)polymers and combinations of two or more thereof.