The invention relates to a light-tight and biologically safe package for food products, especially for liquid, pasty, powdery or granular food products, the preparation thereof and the use thereof.

Background of the Invention

The packaging and storing, shipping and distribution of light-sensitive liquid or pasty food products is a problem that has not yet been solved to general satisfaction. Especially if the food product in question is to be stored/shipped in a biologically safe way, conventional packaging materials, such as polymeric plastic compounds and light-tight support materials coated with such plastic compounds, are not suitable. This is because these plastic compounds cannot be prevented from releasing significant amounts of monomer compounds, plasticizers etc. into the packaged food product and thereby adversely affecting the quality of the food product. Although the use of biologically safe polymers, such as waxes or beeswax, for the impregnation of papers has long been known (see, e.g., US 3,533,208 and 2,378,521 and GB 302,367), the packaging materials/waxed papers obtained thereby do not exhibit sufficient stability or water impermeability to be suitable for the long term packaging of liquid or pasty food products.

Also, the use of tinted glasses is not optimal for weight and cost reasons.

Thus, the object was to provide a packaging by means of which light-sensitive liquid or pasty food products can be packaged in a biologically sound and safe way so that the constituents of the respective food products are not degraded or damaged by the influence of light and thus can be stored in a biologically sound and safe way.

Summary of the invention

It has now been found that a cardboard container coated with a sufficient amount of beeswax represents a suitable stable, opaque and biologically safe packaging. Thus, the invention relates to (1) a light-tight and biologically safe packaging container for food products, consisting of cardboard spray-coated with at least 0.15 g/cm ² of organic beeswax on the inside thereof;

(2) a process for preparing a packaging container according to (1), comprising

(a) preheating the cardboard blank at 60 to 70 °C; and

(b) spray-coating the inside of the heated cardboard blank with the organic beeswax at a spray-chamber temperature of 60 to 70 °C; and

(3) the use of the packaging container according to (1) for the storage of food products.

Brief Description of the Figures

Figures 1 and 2 show specific Examples of the cardboard container according to the invention by longitudinal sectional view, and Figure 3 shows the section according to III in Figures 1 and 2.

Detailed Description of the Invention

The packaging container according to embodiment (1) of the invention (hereinafter also briefly referred to as "cardboard packaging") may be round, edged or have any other shape and consists of (previously recycled) paper that yields a stable solid board if stacked one on top of the other in several layers depending on the desired thickness of the package. The wall thickness of the solid board may be from 0.5 to 3.0 mm, preferably from 0.8 to 1.5 mm. The inner layer of this package, i.e., the layer facing the interior space of the packaging container, is preferably a test liner paper, and this inner layer is soaked and coated with organic beeswax, so that the medium to be stored comes into contact only with naturally occurring, biologically safe wax. Also, the lid and bottom of this packaging are coated in the same way.

The cardboard package is preferably a box, especially a reclosable box in which the inner side of the lid is also coated with organic beeswax. In a reclosable box, the upper edge of the box body has a bead-like thickened portion, and the lid has a groove-like recess for accommodating the bead of the box body.

The packages are shockproof, stackable, from the outside to the inside and from the inside to the outside, liquid-impermeable. The packaging container according to the invention preferably has an average inside coating of organic beeswax of from 0.015 to 0.060 g/cm ² , preferably from 0.020 to 0.040 g/cm ² . It is to be taken into account that local variations of the coating amount may absolutely occur due to the geometry of the container and the application method (e.g. by spraying), the liquid-impermeability of the container is, however, guaranteed.

The organic beeswax applied may be a pure compound or a mixture of several organic beeswaxes, but it necessarily consists exclusively of biologically sound organic beeswaxes and is free of any chemical additives, polymer compounds, solvents, detergents and the like. However, unchanged natural beeswax of a batch is particularly preferred.

The container according to the invention (including its lid, if any) may also be coated on the outside, wherein the outside coating material may be identical with or different from that of the inside coating. Further or alternatively, the container (including its lid) may be printed on the outside.

The container according to the invention is suitable, in particular, for the storage, transport, packing of light-sensitive food products of liquid, pasty, powdery or granular consistency, and is preferably suitable for packing honey or syrups.

The container according to the invention is shockproof, impact-resistant and stackable, in both unfilled and filled conditions.

The process according to embodiment (2) of the invention may further comprise one or more of the following steps:

(c) cooling the coated packaging container;

(d) coating the packaging container on the outside thereof (including the lid and bottom); and

(e) printing the packaging container (including the lid and bottom).

If there is a lid, it may also be processed in a separate coating and printing process as set forth above.

In the following, two embodiments of the invention are illustrated by means of the Figures:

The packaging container 1 according to a first embodiment, as shown in Figures 1 and 3, is a cylindrical box with a lid 4 closing one front side and a bottom 3 closing the other front side. In order to attach the lid 4 to the box, its edge 9 closing the front side is outwardly beaded to form an annular bead. On its peripheral edge, the lid 4 is provided with a circumferential groove-like recess 10, which is designed to accommodate the bead. By engaging the lid 4 onto the beaded edge 9 of the box 1, the lid 4 can be releasably connected with the box 1.

The opposing front side of the box 1 is provided with an inwardly beaded edge 8 having a circumferential groove for a collar 12 of the bottom 3, which is correspondingly circumferential. The bottom 3 is connected with the box 1 by engaging the collar 12 into the groove of the beaded box edge 8.

The cylindrical wall 2, the bottom 3 and the lid 4 of the box 1 are formed from the layer structure as shown in Figure 3. An outer cardboard layer 11 and an inner cardboard layer 5 form a layered cardboard with a wall thickness within a range of from 0.8 to 1.5 mm. On its outside, the outer cardboard layer 11 is provided with a thin coating 7, e.g., of beeswax. The inside of the inner cardboard 5 is provided with an organic wax coating 6, preferably within a range of from 0.02 to 0.04 g/cm ² .

The second embodiment of the packaging container 1' is shown in Figs. 2 and 3. The second embodiment differs from the first embodiment by the lid 4' and the edge 9' of the container 1'. The edge 9' closing the front side of the box 1' according to the second embodiment is not beaded. The lid 4' of the second embodiment differs from the lid 4 according to the first embodiment does not have any circumferential recess, but is rather employed with an inner cylindrical side wall 14, the outer diameter of which corresponds to the inner diameter of the cylindrical wall 2 of the box 1'. The lid 4' also comprises an outer cylindrical side wall 13, the diameter of which corresponds to the diameter of the cylindrical box side wall 2 and which covers an upper part of the inner cylindrical side wall 14 of the lid 4'. Thus, the lower portion of the inner cylindrical side wall 14 fits into the cylindrical wall 2 of the box 1' such that the lid 4' can be releasably connected with the box 1' by contacting engagement of the inner cylindrical wall 14 of the lid 4' within the cylindrical wall 2 of the box 1'. When connected with the box 1', the outer cylindrical side wall 13 of the lid 4' contacts the upper edge 9 of the box side wall 2 and thus forms a smooth outer cylindrical surface of the box without any projection or recess between the lid 4' and the box 1'.

The outer cylindrical side wall 13 of the lid 4' contains the circumferential groovelike recess similar to recess 10 of lid 4 according to the first embodiment. This recess is designed to accommodate the inner cylindrical side wall 14 and an upper circular disk 15 closing the top of the lid 4'. The lower edge of inner cylindrical side wall 14 contains a corresponding recess which is designed to accommodate a lower cylindrical disk 16 closing the lower portion of the lid.

The invention is further illustrated by means of the following Examples.

Examples

Example 1 : Preparation of the coated cardboard box

A standardized round cardboard sleeve with an inner diameter of 80 mm and wall thicknesses of from 0.6 to 2.0 mm and a length of 100 mm was provided with a bottom (beaded) on one side thereof. After several tests with thicker walls and also with thinner walls, it was found that a wall thickness of 1.0 mm or 1.2 mm was optimally suitable for processing.

In a first experiment, wax was heated to slightly above its melting point and applied to the inside of a cardboard box using a paintbrush. Of course, a uniform coating could not be achieved by using a paintbrush, because the wax cooled down more quickly in some spots and less quickly in others.

The wax could be applied much more uniformly by spraying on a preheated cardboard box. Thus, a cardboard box, which had previously been freed from dust, was preheated in a heating chamber and then transferred into the actual coating room. The liquid organic wax was filled into a spraying device, which had also been heated, and sprayed into the interior of the cardboard box within the chamber heated at 60 °C to 70 °C. The thus sprayed-on wax now soaks the inner paper layer of the box and covers it by a thin film of organic wax. Boxes containing different proportions of organic beeswax were prepared, which were coated on average with 4, 6, 8 and 10 g of beeswax. After the boxes had cooled and the organic beeswax had cured, the boxes can be loaded in the same way as before the spraying process, i.e., the "organic box" is shockproof, impact-resistant and stackable.

Example 2 : Use test of the cardboard box

The boxes were filled with honey to test the effectiveness of the interior coating. It was found that an amount of wax of 6 g on average is required for one box (with a diameter of 80 mm and a height of 100 mm) in order to seal the container from the inside in such a way that no liquid will leak out in 20 days. This corresponds to an average coating density of 0.02 g/cm ² of organic beeswax. The filled boxes are also shockproof and impact-resistant and stackable.