FI84197C - Packaging box for liquids - Google Patents

Description

Liquid packaging board 84197

The present invention relates to a liquid packaging board which, in the course of its manufacture, is mass-glued with conventional adhesives which increase dry strength and possibly also hydrophobicity, such as starch- and ketene-dimer-based adhesives.

Liquid packages are usually coated on both sides with various moisture-resistant coatings.

Increasing the hydrophobicity of the board can be considered as a precaution for the packaging itself. Hydrophobicity may be tested if the coating is possibly damaged, or if the coating remains defective during the manufacture of the package due to the manufacturing method or due to a manufacturing defect, for example in the seam area. Cardboard reinforced in terms of hydrophobicity is likely to fulfill its function adequately even in these exceptional situations, for example in high-speed food packaging.

Instead, the better hydrophobicity of the board may be an advantage in the manufacture of packaging. Manufacturing conditions are humid, and cardboard with low hydrophobicity may change its dimensions due to moisture swelling to such an extent that the susceptibility of machines that manufacture and fill packaging increases.

In order to increase the hydrophobicity of the board, 30 e.g. alkyl ketene dimer - based adhesives (so - called.

AKD adhesives). In the gluing of paperboard, these adhesives are used in amounts of the order of about 0.1 to 0.5%, usually about 0.2% by weight of the fiber. These adhesives also provide the board with good lactic acid resistance, 55 which is particularly important when the board is used in milk packs which, after being packed on the inner surface, have an open seam at the end edge.

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However, aseptically packaged packages have proven to be a problem area in the use of liquid packaging boards. The carton used for these packages must be run through an oxidizing peroxide bath immediately prior to forming and filling the package to provide a bacteria-free package. This packaging technique is used, for example, in the packaging of fruit juices, which should remain packaged for several months.

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In the hydrogen peroxide treatment of the board, the board is passed through a bath with a hydrogen peroxide content of about 35%. To ensure effectiveness, the bath is still kept quite hot, about 80eC.

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On the flat surfaces of the board, this treatment does not cause a problematic wetting and hydrogen peroxide stress, because the board has a coating chosen according to the intended use, for example a plastic coating. Instead of stress, the sensitive areas are the edges of the board, which do not have a coating.

However, even under normal operating conditions, this stress on the edges does not become a problem, as the delay of the board in the bath is short.

25 Downtime is a problem. The packing line may need to be stopped momentarily for a number of reasons. The apparatus has provided for these situations by draining the peroxide solution from the treatment plant, but nevertheless the extra delay has been found to have a swelling effect on the uncoated edges of the board. The peroxide is apparently able to cleave the bonds formed by conventional hydrophobic gluing and water can penetrate the fibrous structure. This results in the cardboard swelling at its edges.

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Cardboard with swollen edges no longer passes through the packaging line without interruption, in which case the web must be cut off and the damaged part must be removed. This causes material-slippage and, above all, a delay due to track interruption and re-export.

A substantial improvement in these peroxide bath problems has been achieved according to the invention by using adhesives based on alkyl succinic anhydride (so-called 10 ASA adhesives) in the manufacture of board in addition to conventional dry and possibly hydrophobic adhesives. The recommended amount of glue to use is about 0.05 to 0.30% of the amount of fiber. In particular, this amount is about 0.05 to 0.10%. The pH used for gluing can range from 4 to 10.

The effects provided by the invention are illustrated in the following examples:

Example 1 20

Liquid packaging board (basis weight 150 g / m2) was made from bleached sulphate pulp with birch / pine in a 60/40 ratio as raw material. It was ground to a SR 21 degree of infiltration and had a pH of 9. In an apparatus simulating a conventional board production line, the following chemicals were added to the pulp in pulp flow order (amounts in% by weight of fiber) 30 a) Wet strength resin (Kymene 709): 0.08% b) ASA glue (Raisafob MF): 0.06 and 0.10% c) AKD glue (Raisafob 940): 0.18% d) Pulp starch (Raisamyl 150): 0.30% 35 No surface sizing was used for the board. The ASA adhesive was dispersed in Raisamyl 150 starch solution (amount not included in the above starch dosage) in a ratio of 1/1 and 4 84197 was raised as a 1% solution.

Three test runs were performed with the variable amount of ASA glue (0, 0.06 and 0.10%). From the results, 5 coated cardboards were measured, the lactic acid resistance and peroxide resistance of the peripheral region of the so-called With the REP test, i.e. the edge absorption test. In this test, a low test result value means low absorption of the substance in question on the board through the edge region. The results were as follows.

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Experiment_1_2_3_ AKD,% 0.18 0.18 0.18 15 ASA,% 0 0.06 0.10

Lactic acid 0.65 0.68 0.65 REP kg / m2 1%, 24 h H 2 O 2 1.5 0.65 0, 55 20 REP kg / m2

35%, 5 min, 80 ° C

Example 2 In this example, a series of experiments similar to Example 1 were performed under somewhat different conditions. The pulp used was unbleached sulphate pulp ground to a permeability of SR 18. The pH of the pulp was 7.

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The following chemicals were added to the pulp: a) Pulp starch (Raisamyl 150): 1.0% 35 b) AKD adhesive (Raisafob 940): 0.27% c) ASA adhesive (Raisafob MF): 0.05 and 0.10%

Claims (3)

5 84197 The results were: Experiment_1_2_3_ AKD,% 0.27 0.27 0.27 ASA,% 0 0.05 0.10 Lactic acid 0.51 0.58 0.58 REP kg / m2 10 1%, 1 h H 2 O 2 1 .20 0.80 0.48 REP kg / m 2 2 35%, 5 min, 80 ° C 15 It can be seen from the results that the peroxide resistance of the board was clearly improved by ASA gluing, without any adverse effect on the lactic acid resistance. Liquid packaging board for use in aseptic packaging, glued with a conventional starch glue to increase the dry strength of the board, and optionally mass glued with a conventional hydrophobic glue to increase hydrophobicity, characterized in that the board is additionally glued with an alkyl succinic anhydride. Liquid packaging board according to Claim 1, characterized in that an adhesive based on alkyl succinic anhydride is used in an amount of 0.05 to 0.30% by weight of the fiber. 35 6 84197 Liquid packaging board according to Claim 2, characterized in that an adhesive based on alkyl succinic anhydride is used in an amount of 0.05 to 0.10% by weight of the fiber. 5 10. alkylbärn- stensyranhydride baserande lim. 2. Vätskeförpackningskartong enligt patentkravet 1, kännetecknad därav, att det päyl alkylbärnsten- syranhdyrid baserande limim a iutän i i 0.05 - 0.30% av fibervikten. 3. Vätskeförpackningskartong enligt patentkravet 2, kännetecknad därav, att det päyl alkylbärnsten- syranhdyrid baserande limim a iutän i 0.05 - 0.10% av fibervikten.