EP2792609A1 - Packaging container for bulk materials - Google Patents

Abstract

In a packaging container (1) for bulk materials, in particular a bag or bag, made of a flexible plastic film (2) with a venting device, a particularly simple design and production is to be achieved. This takes place in that the flexible plastic film (2) is formed in two layers, at least in a partial area that the inner layer of the plastic film (2) inner vents (11), that the outer layer of the plastic film outer vents (10) and that inner vents (11) and the outer vents (10) are spaced from each other.

Description

The invention relates to a packaging container for bulk materials, in particular a bag or bag, made of a flexible plastic film with a venting device, wherein the flexible plastic film is formed in two layers at least in a partial area and the inner layer of the plastic film has inner vents, the outer layer of the plastic film outside Having vents and the inner vents and the outer vents are spaced from each other.

Such packaging containers are used to accommodate in particular pourable or pourable products such. As food, fertilizers, granules or building materials. Such pourable contents are produced in various industries, but required for further processing in a manufacturing process elsewhere. With the help of the packaging containers, the filling or bulk goods can be transported, stored temporarily or placed on the market in the case of an end product received therein. Such packaging containers were formerly or are in some areas also made of paper bags. When stacking such paper containers contained in the paper containers air can escape regularly. However, many substances have to be protected from moisture or, for other reasons, better sealing or better hygienic treatment is required than is possible with paper. Therefore, packaging containers made of plastic films have become widely accepted.

During the filling process of such packages, in addition to the contents, a corresponding proportion of air also reaches the interior of the packaging. In particular, when palletizing or stacking such packaging can therefore create an overpressure, through which the packaging is damaged or ruptures. It must therefore be ensured sufficient ventilation.

A packaging container of the type mentioned is from the DE 1 809 578 A known. Here, a bag or bag is described, which consists of at least two film layers, each individual film layer is provided with perforations, these perforations are laterally offset from each other in the finished bag. The film layers lie loosely in the region of the perforations. In this arrangement of the perforations one foil layer covers the perforations of the other. As a result, the ingress of water, for example rain water, in the bag as well as the leakage of the bulk material enclosed in the bag is largely prevented, while the outside air or enclosed by the pneumatic filling process inside the bag air between the loosely superimposed film webs of the perforations of the inner film layer the perforations of the outer and vice versa can get.

The EP 1 607 339 B1 describes for this purpose a ventable bag, which is double-layered in a strip in which the film are glued to form the bag or a circumferential tube. In this double-layered area of the packaging wall, a venting device formed by perforations and partially closing transverse seams is provided.

A similar packaging is in the DE 10 2006 017 229 B4 described. There is a wall portion also formed of an inner layer and at least one outer layer, between these layers at least one conduit member for the air-permeable surface pieces passing air flow is arranged.

From the US 2012/0196060 A1 a packaging is known which has a one-way pressure relief valve, wherein between two foil layers an air channel is formed, which forms a pressure relief valve.

The invention has for its object to provide a packaging container of the type mentioned, which has a producible with very little effort venting. Furthermore, the invention has for its object to provide a method for producing such a packaging container.

The solution of this object is achieved with the features of claim 1. The method of solving the problem with the features of claim 14. Advantageous embodiments of the invention are specified in the dependent claims.

In a packaging container for bulk materials, in particular a bag or bag, made of a flexible plastic film with a venting device in which the flexible plastic film is formed in two layers at least in some areas, the inner layer of the plastic film has inner vents, the outer layer of the plastic film has outer vents and the inner and outer vents spaced from each other, is essential to the invention provided that the two layers that form the two-ply plastic films, such area and at least over the inner vents and the outer vents are releasably connected to each other so that the two layers only at solve a resulting inside the packaging container pressure from each other. This creates a valve. The packaging container is closed and moisture can not penetrate. Only when an overpressure occurs, for example when stacking such packaging containers, the two layers of the two-ply plastic film from each other and thus allow a controlled release of air from the packaging container without this would burst. This creates a particularly simple venting device.

The plastic film itself is double-layered. Two layers of a plastic film are not superimposed in the bag geometry, which would result in a thickened area in the bag which also adversely affects the windability. The two layers form the plastic film itself and together have a thickness and strength required for the mechanical requirements. Although it is conceivable to equip each individual layer with a sufficient thickness and strength for the stability of the packaging container, but this would lead to avoidable additional costs. Therefore, only the two-ply plastic film preferably satisfies the mechanical requirements for the stability of the packaging container. The layers of the plastic film are preferably the same thickness or the same thickness. In some embodiments, however, it may also be preferred that one of the plastic films make up 60% or 70% of the total thickness and the other plastic film make up only 30% or 40% of the total strength. In the case of different thicknesses of the plastic film, it is preferred if the thicker layer of the plastic film is arranged on the outside of the packaging container. The venting device is formed within the two-ply plastic film itself. The inner vents in the inner layer of the plastic film are spaced from the outer vents in the outer layer of the plastic film so that some air passage through the two bonded layers of the plastic film would be necessary. Thereby the penetration of air but also e.g. prevented from moisture. A leakage of air takes place only during the venting process, if by pressing together a certain pressure from the inside of the inner vents is present. For this purpose, the connection of the two layers of the plastic film is releasably equipped. This releasable connection is preferably designed as an adhesive bond.

It is conceivable that in packaging containers composed of several partial surfaces, either only the upper side or only the lower side of the bag or top and bottom or only the gussets of the bag are formed from a two-ply plastic film. This especially if due to the manufacturing technology, the gussets are inserted separately.

However, it is particularly preferred to produce the packaging container in its entirety from a two-ply plastic film. As a result, the production can be done very easily.

The inner layer and the outer layer of the plastic film are preferably formed without tools adhering to each other. Such an adhesive connection is adhesive and tool free. Such a mutually adhering compound that is tool-free, can also be referred to as a dry connection, as this particular is also free of liquid. This can be achieved by bringing the layers of the films together at an elevated temperature, but below the welding temperature of the films to be joined together. The films are therefore preferably in a temperature range between 30 ° C and 100 ° C, in particular between 30 ° C and 90 ° C, more preferably between 30 ° C and 80 ° C, even better between 30 ° C and 70 ° C and in particular between 40 C ° and 60 C ° have been joined together flat. Preferably, the adhesive force of the sheet layers connected together in a sample withdrawal test with a clamping length of 25 mm, a sample width of 15 mm and a parallel sample length of 100 mm 0.1 Newton / 15 mm to 0.8 Newton / 15 mm, in particular 2 Newton / 15 mm to 8 Newton / 15 mm and more preferably 3 Newton / 15 mm to 7 Newton / 15 mm. The measurement is carried out according to DIN 53 357 "Testing of plastic sheets and films in the separation test of the layers". 15 mm wide strips are removed by means of strip cutter. This is usually done in the transverse and in the longitudinal direction of the film travel direction. The samples are separated manually and the strips are clamped in a tensile testing machine and tested (speed 100 mm / min, peel angle for flexible films 90 °). In some embodiments, an adhesive or Adhesive or other aid can be used, which advantageously supports the adhesion of the two layers to each other. The adhesion of the two layers is dimensioned such that they adhere to each other, when pressure occurs or during the venting and the air entering through the inner vents diverges so that an air passage from the inner vents to the outer vents is possible. One speaks of a "peeling" of the two layers from each other. Although a release material can be used for the successive layers, but is not necessarily required. The adhering layers are preferably made at least on the mutually facing sides of thermoplastics, preferably polyethylene and its copolymers. Also conceivable are thermoplastic elastomers and acrylates or even polyurethanes, as well as other materials which promote adhesion. The individual layers are preferably composed of 2 or 3 layers. However, embodiments are also conceivable in which the individual layers of the film consist of 4, 5, 7, 9 or even more layers. It is also conceivable another design of the surface connection of the two layers. The connection of the two layers is designed so that in a venting process, the connection between the inner layer of the plastic film and the outer layer is broken at least in the area between the inner vents and the outer vents, so that a vent from the inner vents to the outer vents between the inner layer and the outer layer of the plastic film is possible. The connection is preferably such that the two layers of the two-ply surface-connected plastic film only come apart at a minimum opening pressure in the packaging container of 50 hPa (hectopascal). In a preferred embodiment, this release takes place only at a minimum opening pressure in the packaging container of 100 hPa. Particularly preferably, the film may also be connected to one another in such a way that the two layers only separate from one another at a minimum internal pressure of at least 250 hPa. Typically, this minimum opening pressure is achieved by press belts, which generate a corresponding pressure. This minimum opening pressure must be increased compared to the ambient pressure of typically 1013 hPa.

The inner vents and the outer vents are preferably evenly distributed over the entire area in which more packaging container is formed from a two-ply plastic film. Preferably, therefore, when forming an entire wall as a two-ply plastic film, a uniform distribution of the inner and outer vent openings is provided via at least one wall. In a packaging container which is formed entirely from a two-ply plastic film, in a preferred embodiment, at least one wall is provided completely uniformly with ventilation openings and in another preferred embodiment, the entire packaging container is uniformly provided with ventilation openings.

In a preferred embodiment of the invention, the inner vents and the outer vents each by at least three millimeters, preferably by at least 5 millimeters and in a configuration in which an even higher pressure must be present to allow the air line to the outside, are the outer vents and the inner vents each spaced at least 10 or even 20 millimeters apart. The distance distribution is relatively uniform. This means that the upper limit of the distances is usually two, three or five millimeters larger than the minimum distance. Thus, there is preferably a distribution of either five to nine millimeters of separation between the inner and outer vents or, for example, between 10 and 14 millimeters or between 20 and 25 millimeters. The distances can be up to 450 mm.

In another preferred embodiment of the invention, the packaging container has gussets and the inner and the outer Vents are arranged in the gussets. This is possible both in the embodiment in which only the plastic film used in the gussets is formed in two layers, as well as in the embodiment in which the plastic film of the entire packaging container is formed in two layers. The gusset can be divided into two halves on each side. Preferably, the inner vents of the inner layer on one side and the outer vents of the outer layer on the adjacent region of the gusset one side of the bag are arranged. Preferably, in a typically directional and predetermined position of the bag, the orientation is such that the outer vents are placed in the lower gusset while the inner vents are placed in the upper gusset. This would have to migrate from the outside entering moisture, which is obviously difficult. The attachment of the vents in the gussets preferred because it also the vent by pressing a punch from the top is much easier, since the air can then escape freely to the sides. In principle, the vent openings can also be arranged on the top or the bottom. The arrangement of the vents is freely selectable within the scope of the invention.

The vents themselves may be formed in a variety of forms. Preferably, the vent openings are slit-shaped. Furthermore, a plurality of vents are preferably provided in a row one above the other. The arrangement of slot-shaped vents has, in particular, the manufacturing advantage that they are relatively simple, in contrast to e.g. to punched, can be introduced on a continuous film web. The vents are formed in another preferred embodiment as perforations.

In a preferred embodiment of the invention, the packaging container has at least one strip-shaped region in which the plastic film overlaps one another and the venting device is arranged outside this strip-shaped region. For the production of a plastic film is typically connected in a tubular manner. For this purpose, the two ends are folded together and glued or welded in an overlap area. In this area, the venting device is typically arranged in the prior art. For this purpose, this area must be made comparatively wide. With the invention, the venting device is arranged outside of this strip-shaped region. The strip-shaped region, in which the plastic film overlaps one another on top of one another, can therefore be made comparatively narrow and can also be placed at any desired location, so that the printed image and the entire appearance of the packaging container are as little influenced as possible. It is also preferred that the strip-shaped area is glued only with a seam. If a channel for a venting device is formed in the strip-shaped region, then at least two spaced apart adhesive strips, bonds or weldings are necessary, whereby a higher use of corresponding longitudinal web material is necessary.

In a method for producing the above-mentioned packaging container, it is essential to the invention that ventilation openings are introduced in a first plastic film section, ventilation openings are introduced in a second plastic film section, and that the first plastic film section and the second plastic film section are brought together to form a two-ply plastic film after introduction of the vent openings wherein the two plastic film sections adhere to each other and from the thus formed plastic film, the above-mentioned packaging container is formed.

In this case, the first plastic film section and the second plastic film section may be separate webs or may be a continuous web which is folded or stacked after the introduction of the vent openings. It is essential, however, that the Vent openings of the first plastic film section are not congruent to the vents of the second plastic film section.

Preferably, the folding of the plastic film sections takes place at temperatures above 30 ° C, preferably at temperatures between 30 ° C and 100 ° C, in particular between 40 ° C and 60 ° C. Also, temperatures between 30 ° C and 90 ° C, 30 ° C and 80 ° C and 30 ° C and 70 ° C may be preferred. At these temperatures no welding of the films takes place, but adhesion is achieved. This applies in particular to polyethylene and preferably also to LDPE, ie low-density polyethylene films. These are preferably used here. As a result, adhesion of the double-layered plastic film thus formed is achieved. Upon application of pressure, the layers are released and there is a peeling of the two-ply plastic film, so that the venting takes place.

The invention will be further explained with reference to a preferred embodiment shown in the schematic drawing.

1 with a packaging container is referred to, which is designed here as a gusseted bag, which has a filling material enveloping the plastic film 2. The packaging container has a front wall 3 formed with the plastic film 2, a rear wall 4, and two lateral walls 5 and 6 in the form of side folds. In the front wall 3 of the packaging container 1, an overlap region 7 is shown, in which production technology typically the ends of a film web are superimposed and connected. In this, the vent area has typically been arranged in the prior art. In the packaging container 1 according to the invention, the vent openings can be arranged at any desired location outside the connection region 7. The connecting region 7 can be made arbitrarily narrow in the illustrated embodiment. All that needs to be done is that a connection between the film webs is made. The Inclusion of the vent area in this overlap area 7 is not necessary. The upper layer is denoted by 20 in this connection region. If the packaging container as a whole consists of a two-ply plastic film, then this is in the overlap region 7 a total of four layers, because two layers are adhesively bonded to each other surface. The overlap area may have widths of 20 mm to 30 mm. This is sufficient for a secure connection of the plastic film. With a design of the overlap area with a vent widths of 80 mm to 140 mm were common in the prior art. These two flat adhering layers form a plastic film. The two superposed end portions of the respective two-layered plastic film are connected to each other in the overlapping region 7 by gluing or welding. The venting device is here formed by slot-shaped vent openings 10, which are arranged in the lower side fold 8 of the side wall 5 and are arranged exclusively in the outer layer of the two-ply plastic film 2. The associated inner vents 11, which are also formed slit-like, are arranged exclusively in the inner layer of the two-ply plastic film 2 and actually not visible in the figure, since they are hidden by the outer layer, but drawn here for clarity. These are arranged here in the upper side fold 9 of the side wall 5. The moisture penetrating from the outside would therefore have to reach vertically upwards from the outer ventilation openings 10 in the case of a usually horizontally mounted packaging container 1 to the inner ventilation openings 11. This provides effective moisture protection. At the same time the venting is possible. Preferably, similar vents are additionally arranged in the second side wall 6. The packaging container 1 is closed at the top with an upper transverse seam 18 and at the bottom with a lower transverse seam 19. Since the vents can be introduced in a continuous form in the plastic film 2, any length configuration of the packaging container 1 is possible without having to special Configurations of a possible chamber-like venting device would have to be considered.

All the features mentioned in the preceding description and in the claims can be combined in any selection with the features of the independent claim. The disclosure of the invention is thus not limited to the described or claimed combinations of features, but all meaningful combinations of features within the scope of the invention are to be regarded as disclosed.

Claims (15)

Packaging container for bulk goods, in particular sack or bag, of a flexible plastic film (2) with a venting device,
wherein the flexible plastic film (2) is formed in two layers, at least in a partial area, and the inner layer of the plastic film has inner ventilation openings (11),
the outer layer of the plastic film has outer vents (10) and the inner vents (11) and the outer vents (10) are spaced from each other,
characterized,
that the two layers forming the two-ply plastic film (2), area at least over the inner vent holes (11) and the external vent openings (10) are away so connected detachably to one another, that the two layers only when an emerging in the interior of the packaging container Release overpressure from one another. Packaging container according to claim 1, characterized in that at least one wall of the packaging container (1) from the two-ply plastic film (2) is formed. Packaging container according to claim 1, characterized in that the packaging container (1) is formed completely from a two-ply plastic film (2). Packaging container according to one of the preceding claims, characterized in that the inner vents (11) and the outer vents (10) distributed uniformly over the entire area are in which the packaging container from the two-ply plastic film (2) is formed. Packaging container according to one of the preceding claims, characterized in that the two layers of the two-layer surface-connected plastic film (2) only at a minimum opening pressure in the packaging container of at least 50 hPa separate from each other. Packaging container according to one of the preceding claims, characterized in that the inner vent openings (11) and the outer vent openings (10) are each spaced at least three millimeters apart. Packaging container according to one of the preceding claims, characterized in that the inner layer of the plastic film and the outer layer of the plastic film are formed without tools adhering to each other. Packaging container according to one of the preceding claims, characterized in that the two layers of the plastic film (2) is formed at least on the mutually facing sides of polyethylene or its copolymers. Packaging container according to one of the preceding claims, characterized in that the packaging container (1) has side folds and that the inner vent openings (11) and the outer vent openings (10) are arranged in a side fold (5). Packaging container according to one of the preceding claims, characterized in that the vent openings (10,11) are slot-shaped and that in a row behind one another a plurality of slot-shaped ventilation openings are provided. Packaging container according to one of the preceding claims, characterized in that the packaging container (1) has at least one strip-shaped region (7) in which the plastic film overlaps one another and in that the ventilation openings (10, 11) are arranged outside this strip-shaped region (7). Packaging container according to one of the preceding claims, characterized in that the packaging container (1) has at least one strip-shaped region (7) in which the plastic film overlaps one another and the overlapping superimposed plastic films are connected to each other with only one adhesive seam. Packaging container according to one of the preceding claims, characterized in that the connection of the two layers of the two-ply plastic film (2) is designed so that the compound dissolves in a venting operation, so that a vent from the inner vent openings (11) to the outer vents (10) takes place between the two layers of the two-ply plastic film. A method for producing a packaging container according to any one of the preceding claims in which
are introduced into a first plastic film section vents,
be introduced into a second plastic film section vents,
the first plastic film portion and the second plastic film portion are brought together after the introduction of the vents to form a flexible plastic film, and
is formed from the thus produced plastic film of the packaging container. A method according to claim 14, characterized in that the merging of the first plastic film section and the second Plastic film section at temperatures between 30 ° C and 100 ° C, in particular between 40 ° C and 60 ° C.

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