DE102013000038A1 - Bag for transporting filling material from manufacturer to user, has plastic wall that is partially double-layered with two adjacent layers, where layers are lifted from each other in area of perforations due to overpressure - Google Patents

Abstract

The bag has an outer wall, which is closed from a flat material into a tubular shape by a longitudinal seam, where the outer wall comprises a plastic wall (1) and a paper wall (8), and a bottom is folded at one end of the outer wall. The plastic wall is partially double-layered with two adjacent layers. The two layers have mutually displaced venting perforations and are fixed to each other such that the layers are lifted from each other in the area of perforations due to overpressure.

Description

The invention relates to a bag having a jacket wall which is closed from a flat material to a tubular shape by means of at least one longitudinal seam and having a plastic wall and at least one paper wall, and having at least one bottom which is folded at one end of the jacket wall.

Such bags are known in numerous embodiments. You can have such a stable jacket wall that they can be filled with a product with high weight. For example, bags are common, which are filled with a pourable filling material with a mass of, for example, 5 to 50 kg to transport the contents of the manufacturer to the user.

For cost reasons and for reasons of environmental compatibility, the jacket wall of such bags is formed with stable papers, especially with kraft paper. It is readily possible to form bags with a filling weight of the type mentioned with a single-layer or multi-layer jacket wall made of kraft paper in sufficient stability. However, if the contents are sensitive to moisture, it makes sense to form the jacket wall with at least one closed plastic wall, which is an effective barrier against moisture penetration. In such bags, however, results in particular - if they are designed as valve sacks and are filled via a filler neck of a filling machine - that is enclosed with the contents in the bag interior air, which leads to a bloated sack shape and prevents compacting of the contents inside the bag. Numerous attempts have therefore been made to allow venting of such a bag during filling and after filling.

Out EP 0 867 379 A1 a perforated bag is known in which the perforation extends through all the layers of the bag wall. Although this ensures sufficient air permeability, the protection against moisture is no longer completely guaranteed.

By EP 1 813 545 B1 It is also known to form a bag with multiple layers of paper and provide a plastic liner. The plastic intermediate layer is not hermetically sealed, since the formation of the tubular jacket wall is effected by a longitudinal adhesive seam of the outer paper layer. This longitudinal adhesive seam is formed but interrupted, so that an air outlet is guaranteed for venting of the bag. A disadvantage of this solution, in turn, that the conclusion against exposure to moisture is not complete, so that in particular a long-term exposure to moisture can have adverse effects on the contents.

The present invention is therefore based on the problem to bring about a safe moisture removal in a bag of the type mentioned above while allowing venting during and after filling.

This problem is solved according to the present invention in a bag of the type mentioned in that the plastic wall is at least partially formed with two layers lying two layers, that the two layers each have staggered ventilation perforations and are fixed to each other so that the layers in the area the perforation due to an acting overpressure can stand out from each other.

The present invention is based on the fact that two plastic layers abut each other so that they are closed due to the staggered vent perforation at atmospheric pressure, so that at rest an air or gas exchange between the bag interior and bag exterior is not possible because the plastic layer hermetically encloses the interior. Due to an overpressure, in particular in the interior of the bag, the two plastic layers can separate from each other so that air can escape from the bag via the path of the venting perforations of the lower layer, the space between the two plastic layers and finally the venting perforation of the upper layer. A possibly inflated when filling sack can thus be vented by pressing against the bag wall, which leads to an overpressure in the bag interior, so that a compacting of the contents during filling, but also a subsequent compacting of the contents is possible. The case released from the contents air volume can be removed via the two juxtaposed layers of plastic by the plastic layers are brought by the pressure to lift each other.

Adjacent plastic layers regularly lead to an airtight seal. This effect can be further enhanced by selecting as the material of the plastic layers those materials which bring about a certain surface adhesion. Examples of these are films of low-density polyethylene, of polyvinyl alcohol or the like. Other plastic film materials allow the desired adhesion forces at least after a conventional surface treatment.

In order to facilitate a venting of the entire bag interior, it is preferred that the perforations extend strip-shaped over a length of the bag running perpendicular to the bottom. In this way, venting is possible over the entire length of the bag.

Of course, it is still possible to form such a venting arrangement of superimposed plastic layers not only once, but several times, for example twice, over the circumference of the bag.

In a preferred and easy to manufacture embodiment of the invention, the perforations of the two layers in the width direction are arranged side by side, in particular when the perforations strip-shaped in the longitudinal direction - that is perpendicular to the width direction - extend.

The perforation holes are preferably small and numerous and, for example, have a diameter between 0.2 and 5 mm, preferably between 0.5 and 2 mm, as circular perforation holes. Of course, other forms of perforation holes are possible, such as rectangular or polygonal holes, oval holes o. The like. Of importance is not the shape of the holes, but derer free flow cross-section

In a simple embodiment of the invention, the plastic wall has an applied plastic strip as a second layer. The plastic wall is self-contained and hermetically sealed, but provided with introduced in a suitable form perforation holes. These perforation holes are closed by the applied plastic strip, but in turn has perforation holes, which are not aligned with the perforation holes of the plastic wall, but arranged offset. The second layer may be glued or welded onto the plastic wall at the edges of the plastic strip. Since the plastic layers abutting offer an airtight seal, but it is sufficient to keep them otherwise pressed against each other at the edges of the plastic strip, for example by a seam, by riveting o. Ä.

It is essential for the invention that the two plastic layers can stand out from each other due to their connection by an overpressure to make a vent path free. This is achieved, for example, by the fact that when the two plastic layers are joined to one another, a stretching bias of at least one of the plastic layers is avoided so that they can be lifted from the other plastic layer due to their flexibility or elasticity.

In a variant of the present invention, the formation of the second layer as a separate part can be avoided in that the two layers are formed overlapping ends of the plastic wall, which are fixed to each other on both sides of the perforations. For a given size, it is therefore possible to produce the plastic wall with a corresponding peripheral oversize and to provide in a suitable form with the perforation holes, so that they come to lie next to each other, for example, and in any case are not aligned.

For the present invention it is preferred that the plastic wall is not an outer wall of the bag, but is covered by a paper wall to the outside. The plastic wall can then be an inner wall or an intermediate wall of the jacket wall. In this way, the possibly more sensitive to external influences plastic assembly for venting is covered by a protective paper layer, wherein the paper layer may preferably have a vent slot. Since the paper layer is permeable to gas, the vent slot can be dispensed with if no rapid venting is required.

The invention will be explained in more detail below with reference to an embodiment shown in the drawing. Show it:

1 a schematic plan view of a plastic wall with a second plastic layer to form a venting arrangement;

2 a schematic cross section through a according to 1 constructed bag;

3 a schematic perspective, partially broken away view of the bag according to 2 ,

1 schematically shows a plastic wall 1 with a perforation extending over a longitudinal direction L of a bag 2 having. The perforation consists in the illustrated embodiment of three juxtaposed perforation holes, which are arranged one behind the other in the longitudinal direction L. On the plastic wall 1 is a plastic strip 7 applied, in which this at its longitudinal edges with glued or welded seams 4 hermetic with the plastic wall 1 is sealed. The plastic strip 7 has a second perforation 3 on, in the same way as the perforation 2 the plastic wall 1 trained, but laterally offset. In the illustrated embodiment, the perforation of Kunsttoffwandung 1 in a width direction B, one half of the width of the plastic strip 7 one, while the perforation 3 of the plastic strip 7 on the other half of the plastic strip 7 is arranged.

2 schematically illustrates a cross section through a jacket wall of a bag, which consists of the plastic wall closed to a hose 1 and a surrounding outside, closed to a hose paper wall 8th consists. The paper wall 8th is gas-permeable due to the material, while the plastic wall 1 Gasundruchlässig is. 2 clarifies that the tubular plastic wall 1 is formed from a flat film which seams over a longitudinal welding or gluing 6 closed to the hose. In the same way is the outer paper wall 8th also made of a flat material and by a longitudinal adhesive seam 5 closed to a tube shape.

It need not be further explained here how the sealing of the bag takes place in the area of the at least one floor. From the tubular jacket wall in a known technique bottoms are formed by folding, for example, a crossbase, a block or block bottom, folded bottoms (ends) of flat bags, etc. For the present invention, it is preferred that the bag has a bottom at both ends and can be filled via a valve opening, so is a valve bag.

In the in 2 illustrated embodiment is the plastic strip 7 on the tubular plastic wall 1 applied inside. The function arises in the same way, however, even if the plastic strip 7 outside, ie between plastic wall 1 and paper wall 8th on the plastic wall 1 is attached.

3 illustrates in a perspective view of the structure of a bag formed from a tubular material. The plastic wall 1 is about the glue or weld 6 Hermetically sealed, so gas and moisture impermeable. She is on the suture 6 opposite side with the perforation 2 provided on one half of the width of the plastic strip 7 extends in the longitudinal direction L and from an unperforated part of the plastic strip 7 is covered to the interior of the jacket wall. The plastic strip 7 indicates the perforation on its other half 3 radially outward through an unperforated area of the plastic wall 1 is covered. As the plastic strip 7 over fastening seams 4 on the inside of the plastic wall 1 connected to this is that an overpressure in the interior of the bag to a lifting of the plastic wall 1 from the plastic strip 7 leads, results in this case, a vent path through the perforation 3 of the plastic strip 7 , the space between the plastic strip 7 and the plastic wall 1 for a lateral gas transport and finally through the perforation 2 the plastic wall 1 outward.

As 3 can be seen, is the jacket wall by an outer paper wall 8th completes, so the plastic wall 1 represents an inner wall or an intermediate wall. An intermediate wall is present when on the inside of the plastic wall 1 another paper layer is formed tubular.

It will be readily apparent that the exemplary arrangement of the perforations 2 and 3 is not mandatory for the venting function according to the invention. It just depends on the holes of the perforations 2 and 3 not aligned with each other and by the juxtaposition of the plastic layers 1 and 7 are closed reliably at rest. It is easily possible, the perforation holes of the two perforations 2 and 3 to arrange in interlaced patterns, so as to realize small ventilation paths. The length of the selected ventilation paths depends on the material, the thickness and the adhesion of the plastic layers 1 . 7 and must be chosen so that not even at low pressure the gas-tight closure by the two plastic layers 1 . 7 is opened.

In a variant, the Kunstoffwandung 1 form the vent strip itself by the Kunstsoffwandung 1 is dimensioned so that beyond the adhesive or weld 6 an overlapping strip is created and the two perforations 2 . 3 be introduced in this area. The strip itself must then at its free end also with the plastic wall 1 be hermetically connected to ensure the sealing function. The operation of this embodiment is identical to that of the 1 to 3 described mode of action.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0867379 A1 [0004]
• EP 1813545 B1 [0005]

Claims (8)

Sack with a jacket wall, which consists of a flat material to form a tube by means of at least one longitudinal seam ( 5 . 6 ) is closed and a plastic wall ( 1 ) and at least one paper wall ( 8th ), and having at least one bottom, which is folded at one end of the jacket wall, characterized in that the plastic wall ( 1 ) at least partially in two layers with two adjoining layers ( 1 . 7 ) is formed such that the two layers ( 1 . 7 ) each staggered ventilation perforations ( 2 . 3 ) and are fixed to each other so that the layers in the region of the perforations ( 2 . 3 ) can stand out due to an overpressure. Sack according to claim 1, characterized in that the plastic layers ( 1 . 7 ) have a two-dimensional adhesion to each other. Sack according to claim 1 or 2, characterized in that the perforations ( 2 . 3 ) extend in a strip over a perpendicular to the bottom extending length (L) of the bag. Sack according to one of claims 1 to 3, characterized in that the perforations ( 2 . 3 ) of the two layers ( 1 . 7 ) are arranged side by side in the width direction (B). Sack according to one of claims 1 to 4, characterized in that the plastic wall ( 1 ) an applied plastic strip ( 7 ) as the second layer 4. Sack according to claim 5, characterized in that the second layer on the plastic wall ( 1 ) at the edges ( 4 ) of the plastic strip ( 7 ) is glued or welded. Sack according to one of claims 1 to 4, characterized in that the two layers by overlapping ends of the plastic wall ( 1 ) formed on both sides of the perforations ( 2 . 3 ) are fixed to each other. Sack according to one of claims 1 to 7, characterized in that the plastic wall ( 1 ) by at least one paper wall ( 8th ) is covered to the outside.

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