Environment-Friendly Packaging Paper for Food

Abstract

Discloses is a packaging paper for food having a grammage between 20 g/m.sup.2 and 40 g/m.sup.2, and having a filler content of less than 20 wt. % relative to the weight of the uncoated paper. On at least one side the packaging paper has a coating that contains a vegetable oil encapsulated in a polymer, and also talc and a binder. Both sides of the finished packaging paper have a Cobb 60 value of 14 g/m.sup.2 to 22 g/m.sup.2.

Claims

1. Packaging paper for food with a basis weight between 20 g/m.sup.2 and 40 g/m.sup.2, and with a filler content of less than 20% by weight with respect to the weight of the uncoated paper, wherein the packaging paper has a coating on at least one side, which comprises a vegetable oil encapsulated in a polymer, talc and a binder, and wherein both sides of the finished packaging paper have a Cobb 60 value of 14 g/m.sup.2 to 22 g/m.sup.2.

2. Packaging paper for food according to claim 1, in which said basis weight is at least 25 g/m.sup.2.

3. Packaging paper for food according to claim 1, in which said basis weight is at most 35 g/m.sup.2.

4. Packaging paper for food according to claim 1, in which said Cobb 60 value is at least 16 g/m.sup.2 and/or at most 20 g/m.sup.2.

5. Packaging paper for food according to claim 1, in which the polymer contains a maleimide group and is formed by a copolymer of styrene and maleic anhydride derivatives.

6. Packaging paper for food according to claim 1, wherein the thickness is at least 23 μm, and wherein the thickness is at most 50 μm.

7. Packaging paper for food according to claim 1, in which the Bendtsen air permeability is at most 20 ml/min and in which the Bendtsen air permeability is at least 3 ml/min.

8. Packaging paper for food according to claim 1, which has, in at least one direction, a permeability for water vapor in accordance with ISO 2528:1995 of at least 200 g/(m.sup.2×24 h) and of at most 800 g/(m.sup.2×24 h).

9. Packaging paper for food according to claim 8, wherein the direction corresponds to a transport of water vapor from one side which faces the food when the food is packaged to the outside of the packaging.

10. Packaging paper for food according to claim 1, wherein the opacity in accordance with ISO 2471:2008 is at least 60% and at most 90%.

11. Packaging paper for food according to claim 1, in which the whiteness in accordance with ISO 2470-1:2009 of the side facing away from the food during use or of a side to be printed is at least 80% and at most 90%.

12. Packaging paper for food according to claim 1, which has a tensile strength of at least 1 kN/m and a tensile strength of at most 5 kN/m.

13. Packaging paper for food according to claim 1, in which the base paper has a pulp content of at least 90% by weight, with respect to the mass of the base paper, whereby the content does not exceed 95% by weight with respect to the mass of the base paper.

14. Packaging paper for food according to claim 13, in which the pulp is a wood pulp which is formed by long fiber pulp from spruce wood, pine wood or larch wood, short fiber pulp from beech wood, birch wood or eucalyptus wood, or a mixture thereof, wherein the wood pulp is formed by a mixture of long fiber pulp and short fiber pulp in a mass ratio of 2:1 to 1:2.

15. Packaging paper for food according to claim 13, in which the pulp is unbleached.

16. Packaging paper for food according to claim 13, in which the pulp is formed by pure pulp (“virgin pulp”).

17. Packaging paper for food according to claim 13, in which the Schopper-Riegler degree of refining of the pulp is at least 50°, and at most 80°.

18. Packaging paper for food according to claim 1, in which the base paper contains a filler, the content of which is less than 10% by weight with respect to the weight of the base paper.

19. Packaging paper for food according to claim 1, in which the filler comprises talc, kaolin, titanium dioxide or a mixture thereof.

20. (canceled)

21. Packaging paper for food according to claim 1, in which the coating makes up a proportion of the basis weight of the packaging paper which is at least 0.5 g/m.sup.2, and at most 8 g/m.sup.2.

22. Packaging paper for food according to claim 1, in which both sides of the base paper are coated with said coating, or in which only that side is coated with said coating, which is intended to face the packaged food during use.

23. Packaging paper for food according to claim 22, in which only the felt side of the base paper is coated with said coating.

24. Packaging paper for food according to claim 22, in which only the wire side of the paper is coated with said coating and the felt side of the paper is printed.

25. Packaging paper for food according to claim 1, in which the base paper is coated with said coating on only one side and the other side is coated with starch.

26. Packaging paper for food according to claim 25, in which the amount of starch is at least 0.5 g/m.sup.2, and at most 4 g/m.sup.2.

27. Packaging paper for food according to claim 1, in which said vegetable oil at least partially contains sunflower oil, soybean oil, palm oil or rapeseed oil.

28. Packaging paper for food according to claim 1, in which the sum of vegetable oils in the coating material is at least 20% of the mass of the coating material and at most 60% of the mass of the coating material.

29. Packaging paper for food according to claim 1, in which the binder for the coating material contains a starch, a starch derivative, a cellulose derivative, polyvinyl alcohol or polystyrene acrylate.

30. Packaging paper for food according to claim 29, in which the binder contains a mixture of starch, polyvinyl alcohol and polystyrene acrylate, wherein the proportion of polystyrene acrylate exceeds that of the starch and the polyvinyl alcohol.

31. Packaging paper for food according to claim 29, in which the sum of all binders in the coating material makes up at least 15% and at most 75%, of the mass of the coating material.

32. Packaging paper for food according to claim 1, in which the coating material further contains a filler which comprises a mixture of talc, titanium dioxide and kaolin, wherein the proportion of talc exceeds that of titanium dioxide and kaolin.

33. (canceled)

34. Packaging paper for food according to claim 1, in which the proportion of talc comprises at least 5% by weight and at most 25% by weight with respect to the mass of coating material.

35. Packaging paper for food according to claim 32, in which the sum of the fillers in the coating material is at least 10% by weight and at most 50% by weight with respect to the mass of the coating material.

36. Packaging paper for food according to claim 1, in which the coating material contains less than 2% by weight of wax with respect to the weight of the coating material.

37. Packaging paper for food according to claim 1, in which the coating material consists of at least 70% by weight of materials of biological origin.

38. Use of a packaging paper according to claim 1 for packaging hot or cold fast food.

39. Packaging paper for food according to claim 7, in which the Bendtsen air permeability is at most 15 ml/min and at least 7 ml/min.)

40. Packaging paper for food according to claim 27, in which said vegetable oil contains a mixture of sunflower oil and soybean oil in a mass ratio of about 1:1.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0098] The advantages of the invention will be demonstrated by an exemplary packaging paper for food according to the invention.

[0099] The base paper for the packaging paper according to the invention was produced from the following components.

[0100] As long fiber pulp 48% by weight was used consisting of a mixture of pulps from spruce wood, pine wood and larch wood, and as short fiber pulp 44% by weight consisting of a mixture of pulps from birch wood and eucalyptus wood was used, so that the proportion of pulp in the base paper was 92% by weight. Only titanium dioxide was used as the filler, in a proportion of 7.5% by weight. The rest was attributable to other substances and process aids, in particular a small amount of an alkyl-ketene dimer in the bulk to achieve the desired degree of sizing.

[0101] All values above given as a % by weight refer to the base paper without coating.

[0102] Before the paper production, the pulp was refined to a Schopper-Riegler degree of refining of 60° to 70°, measured in accordance with ISO 5267.

[0103] The base paper was produced on a Fourdrinier paper machine using processes known from the prior art. In the film press of the paper machine, the coating solution was applied to the felt side of the base paper and a starch solution was applied to the wire side, and the paper was then dried to a moisture content of 5% by weight with respect to the weight of the finished packaging paper.

[0104] The coating solution consisted of 36% by weight of water and 64% by weight of coating material, each with respect to the weight of the coating solution.

[0105] The coating material itself contained about 18% sunflower oil, 18% soybean oil, encapsulated in a copolymer of styrene and maleic anhydride derivatives, as well as 7% polyvinyl alcohol, 5% starch and 14% polystyrene acrylate. The fillers were 20% talc, 2.5% titanium dioxide and 9% kaolin. Furthermore, the coating material contained 2% of waxes and about 4.5% of process aids such as dispersing agents. Thus, the coating solution contained more than 70% of materials of biological origin.

[0106] All values are with respect to the mass of the coating material.

[0107] The basis weight of the finished packaging paper (29.5 g/m.sup.2) and of the uncoated base paper (25 g/m.sup.2) were determined in accordance with ISO 536, and by difference from the basis weight, the applied amount of the coatings was 4.5 g/m.sup.2, wherein it is known from experience that the amount of starch applied to the wire side is about 1 g/m.sup.2. Thus, the amount of coating material applied to the felt side was about 3.5 g/m.sup.2.

[0108] The water absorption was determined by the Cobb 60 value in accordance with ISO 535 for both sides of the packaging paper. For the side coated according to the invention, a value of 17 g/m.sup.2 was found, while for the side coated with starch the value was 18 g/m.sup.2.

[0109] The thickness of the packaging paper was measured on a single sheet in accordance with ISO 534 and a value of 31 μm was obtained.

[0110] The Bendtsen air permeability of the packaging paper was measured in accordance with ISO 5636-3 and a value of 9 ml/min was obtained.

[0111] The permeability for water vapor was measured in accordance with ISO 2528:1995 in the direction from the side coated according to the invention to the side coated with starch and a value of about 500 g/(m.sup.2×24 h) was obtained.

[0112] The opacity of the packaging paper was measured in accordance with ISO 2471:2008 and a value of 65% was obtained.

[0113] The whiteness of the packaging paper was measured on the wire side in accordance with ISO 2470-1:2009 and a value of 83% was obtained.

[0114] The tensile strength of the packaging paper was measured in accordance with ISO 1924-2 and a value of 2.0 kN/m was obtained.

[0115] Finally the biodegradability was measured in accordance with EN 13432 “Requirements for packaging recoverable through composting and biodegradation—Test scheme and evaluation criteria for the final acceptance of packaging”. In this test the packaging is stored in a defined compost and a sample is taken at regular intervals. For this sample in the proportion as a % by weight is determined which is retained by a sieve with a mesh size of 2 mm. The packaging fulfills the requirements of the standard if less than 10% by weight of the sample mass is retained in the sieve after 12 weeks.

[0116] For the packaging paper according to the invention it was shown, that even after two weeks less than 0.1% by weight of the sample mass was retained in a sieve with a mesh size of 2 mm, so that it has an excellent biodegradability.

[0117] In order to test the resistance against the penetration of grease, oil and water in an experiment, various foodstuffs were wrapped in the packaging paper according to the invention and in a paper coated with polyethylene. After a defined time period, stains and discoloration of the packaging paper according to the invention were subjectively compared with those on the paper coated with polyethylene. It was shown that over a period of a few minutes up to half an hour, both papers provided an approximately similarly effective barrier against the penetration of grease, oil and water. Over longer periods of time, typically of more than an hour, the paper coated with polyethylene was superior with respect to its barrier effect. The packaging paper according to the invention is therefore preferred for packaging food intended for quick consumption, preferably for food in the area of fast food and most particularly preferred for hamburgers, cheeseburgers or sandwiches.

[0118] The paper according to the invention thus at least in the short term forms a good barrier against the penetration of grease, oil and water and has an excellent biodegradability and can thus combine these two contradicting requirements very well.