EP2857322A1 - Sack and sack manufacturing method - Google Patents

Abstract

A bag (1) with a tubular bag body (1a) is folded at at least one end region of the bag body (1a) into a bottom (1d, 1e). The folded bottom (1d, 1e) is connected to a cover sheet (10, 11) which has at least one tear line (20, 21) defined by cuts, perforations or material weakening.

Description

The invention relates to a bag, in particular box bag or box valve bag, with a tubular bag body, wherein the bag body is folded at least one end portion to a bottom and the folded bottom is connected to a cover sheet, and a method for producing such a bag.

The tubular bag body consists of a tubular material or a flat material joined together at its longitudinal edges.

Bags with folded bottom usually have a box shape or cuboid shape. They offer optimum material surface utilization, good stacking capacity and, due to the cuboid shape, improved volume utilization. In addition to the box shape, there is still the quasi-box shape, which has a rectangular folded bottom on one side and an end closed by an adhesive, welding or sewing seam on the other side.

In order to be able to fill box sacks automatically, valves are made in the manufacture of the bag on a bottom, which consist of either a hose or a sheet material and inserted between the end flaps of the bag body and optionally folded. In this embodiment of box bags one speaks of box valve bags.

Box sacks, box valve bags, or quasi-box sacks usually have a capacity of 10, 25 or 50 kg, for certain applications also up to 1000 kg and are used for the packaging of goods, in particular bulk materials. Box sacks are nowadays commonly made of plastic films or plastic fabrics. Plastic film has no high strength and therefore requires a large material thickness. In addition, it is heat sensitive and not dimensionally stable due to high modulus of elasticity. Plastic fabric of monoaxially stretched plastic tape has a high strength and is dimensionally stable, especially when it is coated. By suitable coating the plastic fabric is also very good printable. Compared to plastic film material consumption is significantly lower when using plastic fabric with the same carrying capacity of the bags. Sacks of fabric made of monoaxially stretched polymer, in particular polyolefin, preferably polypropylene, tapes, which have one or two sides, have proven outstandingly well in practice thermoplastic material, in particular polyolefin may be coated. Such a bag is from the document WO 95/30598 known. The tapes of this fabric are made by stretching polyolefin films 4 to 10 times their original length and cutting the stretched polyolefin film. Alternatively, the film may be cut into strips before drawing and then the strips stretched into ribbons. By the stretching process, the molecular chains are aligned in the ribbon longitudinal direction and have in the direction of stretching about 6- to 10-fold strength over the original state. The ribbon width is usually about 1.5-10 mm, the thickness 20-80 microns. When loaded in the transverse direction, the ribbons splinter, which is why they are woven in round or flat fabric from each other about right-angled warp and weft layers. The fabric then has the same high tensile strength in all directions. Sacks made from such a fabric have been proven for billions of times around the world for the packaging of bulk goods of all kinds for many years.

To achieve dust and moisture proofing and to prevent slippage of tape layers, a coating of melt of preferably the same material as the tapes can be applied and pressed onto the fabric on one or both sides. As an alternative to the melt coating, a lamination of the fabric with plastic film is also provided.

More recently, box sacks made of composite materials have come onto the market, as described in Austrian Utility Model No. 9643. Such a fabric / film composite has a construction of a fabric of monoaxially drawn polymer tapes, in particular polyolefin or polyester tapes, preferably polypropylene or polyethylene terephthalate tapes, an OPP (Oriented Poly Propylene) film and an intermediate connecting layer of thermoplastic or adhesive , The OPP film may be printed on the fabric facing surface. This material structure shows both high strength (through the fabric) and excellent printability (through the OPP film). Since the OPP film is stretched, it also has a very good dimensional stability. Advantageously, BOPP films can also be used, which are so-called Biaxially Oriented Poly Propylene films. To facilitate the connection with other tissues, tissue-film composites or films, it is expedient to provide an OPP film for the fabric-film composite which (at least) has a film seal layer on its surface facing away from the tissue. For the same reason, it is expedient if the fabric of the fabric-film composite on one or both sides with a fabric sealing layer of a thermoplastic Plastic is coated. In order that the tissue is not damaged in the production of the tissue-film composite or in the bonding process of the sack body and cover sheet, at least one of which consists of the tissue-film composite, it is advantageous if the film seal layer and / or the tissue sealing layer has a melting point which is below the crystallite melting point of the tissue band material and the OPP film.

Thus, for example, the following combination possibilities result for the production of a bag: bag body of multilayer film combined with a cover sheet of multilayer film; Bag body of multilayer film combined with a cover sheet of film composite; Bag body of film composite combined with a cover sheet of multilayer film; and bag body of film composite combined with a cover sheet of film composite. Although these embodiments of the bag do not offer the same high strength as the use of a fabric of monoaxially stretched plastic tapes, but this disadvantage can be mitigated by increasing the number of foil layers.

To increase the carrying capacity of the folded bottom, a cover sheet is applied to the folded end tabs of the bag body and connected in a flat manner to the folded bottom. For flat connection of the cover sheet with the bottom fold, for example, a hot air welding method can be used, in which facing coated surfaces of the folded bottom and the cover sheet heated by hot air to plasticization, pressed against each other and then cooled. An alternative bonding method is the surface bonding of the folded bottom and the cover sheet, for example by means of hot melt adhesive.

Basically, bags of the type mentioned above, which were closed with the cover sheets according to the invention, due to the high strength of folded bottom and cover sheet not without further open nondestructive. Since the bonding or welding of the cover sheet with the folded bottom can not be easily solved, such sacks are usually opened by the bag body itself is slashed with a sharp object, but in bags made of a fabric of monoaxially stretched polymer ribbon due to its extremely high strength is difficult to accomplish. After slitting the bag, there is also the problem of poor handling of the opened bag.

The present invention has for its object to find a solution for facilitating the opening of said bags on the folded bottom.

The inventive solution is to provide a bag with a tubular bag body, wherein the bag body is folded at least one end portion to a bottom and the folded bottom is connected to a cover sheet, wherein the cover sheet has at least one defined by cuts, perforations or weakening material tear line , At this tear line, the cover sheet can be torn open without tools. The cuts, perforations or material weakening are preferably produced by means of laser cutting or mechanical punching.

• ein schlauchförmiger Sackkörper bereitgestellt wird;
• ein Boden an zumindest einem offenen Ende des Sackkörpers durch Falten von Endlappen des Sackkörpers gefaltet wird;
• der gefaltete Boden mit einem Deckblatt verbunden wird, insbesondere mittels Heißluftschweißen oder Kleben; und
• im Deckblatt vor seinem Verbinden mit dem gefalteten Boden mittels Schneiden, Perforieren oder Ausbilden einer Materialschwächung zumindest eine Aufreißlinie definiert wird.

The bag according to the invention can be produced in existing or only slightly modified bag confectioning systems by:

• a tubular bag body is provided;
• a bottom is folded at at least one open end of the bag body by folding end flaps of the bag body;
• the folded bottom is connected to a cover sheet, in particular by hot air welding or gluing; and
• is defined in the cover sheet prior to its connection to the folded bottom by means of cutting, perforating or forming a material weakening at least one tear line.

Preferably, the material for the cover sheet is a web material on which the at least one tear-open line is first formed and then the cut-off of the cover sheets in a repeat length is effected by means of cross-sections. The topsheet material may be prefabricated off-line by winding the web material onto a roll after forming the at least one tear line and unwinding from the roll for cutting in the repeat length.

When the bottom is folded such that end flaps of opposing walls of the bag body are folded toward each other, with the end tab of one wall covering the end flaps of the other wall with a cover width, at least one tear line is arranged so as not to overlay the overlapping end flaps. Thus, it is easy for a user to separate after tearing the cover sheet, the overlapping end tabs of the bag body from each other and thus gain access to the bag interior.

If the bottom is folded such that end flaps of opposing walls of the bag body are folded toward each other but the end flaps do not overlap one another, then preferably at least one tear line is arranged to extend between the two end flaps. In this configuration, the user gains access to the interior of the bag by tearing the topsheet along the tear line.

In order to gain access to the interior of the bag over the largest possible area of the bag bottom, it can be provided that the at least one tear line extends over the entire repeat length of the cover sheet.

In some applications, only a small access to the bag interior is desired, or one would like to avoid - with the provision of several tear lines - that a part of the cover sheet is completely torn off. In these cases, it is advantageous if the at least one tear line extends only over part of the repeat length of the cover sheet.

In order to prevent the unintentional tearing of the cover sheet on the tear lines, the at least one tear line can be covered by a releasably adhering to the cover sheet protective tape. Thus, before tearing the cover sheet, the protective tape must first be removed. Subsequently, the tear line can be opened by pulling apart. The protective tape also serves to protect the bag contents from the external environment or to prevent leakage of powdery bag material when the tear line is formed as a perforation or cuts. To be able to grasp the protective tape for peeling easier, it is provided that the protective tape has a free end which does not adhere to the cover sheet. This can be accomplished, for example, by providing a release agent or ensuring that the guard band does not come in contact with an adhesive at the free end.

In particular, for the removal of bulk material, it is advantageous if the cover sheet in the torn-open state not only has a slot-shaped opening, but an opening with a defined width. This can be achieved by providing two tearing lines running parallel to one another in the cover sheet, whereby a strip is torn out of the cover sheet for opening. To be able to grasp these strips torn out more easily, the tear-off lines can be formed at one end as cutting lines. In a preferred embodiment of the bag provided with two tear lines in the cover sheet, the bottom of the bag is folded such that end flaps of opposing walls of the bag body are folded together and the end flap of one wall closes the end flap of the other wall with a cover width Covered, running in half the distance between the two tear lines halving line is offset by half the overlap width to a center line of the bag bottom.

In order to achieve sufficient strength of the cover sheet on the bag according to the invention, it is proposed to produce the cover sheet of a material which is selected from a fabric of plastic tapes, wherein the fabric is optionally coated on at least one side with a plastic layer, or a fabric of plastic tape, the coated on at least one side with an OPP film, or connected to a network structure plastic film. The cover sheet is printable and can therefore serve as a 'display' when unopened.

In order to achieve purity of the cover sheet with the bag body and thereby good recyclability of the whole bag, it is advantageous if the cover sheet is made of the same material as the bag body.

• Fig. 1 zeigt einen erfindungsgemäßen Sack im gefalteten Zustand in Draufsicht.
• Fig. 2 zeigt das erfindungsgemäße Deckblatt in einer perspektivischen Teilansicht von der Stirnseite.
• Fig. 3 zeigt einen Endbereich des erfindungsgemäßen Sackes mit einem aufgebrachten Deckblatt mit Aufreißlinie und Schutzband.
• Fig. 4 zeigt eine Teilansicht eines erfindungsgemäßen Sackes mit einem aufgebrachten Deckblatt mit zwei Aufreißlinien.
• Fig. 5 zeigt einen Ausschnitt des Bodens des Sackes von Fig. 7.
• Fig. 6 zeigt ein bahnförmiges Material zur Herstellung erfindungsgemäßer Deckblätter.

The invention will now be explained in more detail by means of embodiments with reference to the drawings.

• Fig. 1 shows a bag according to the invention in the folded state in plan view.
• Fig. 2 shows the cover sheet according to the invention in a perspective partial view of the front side.
• Fig. 3 shows an end portion of the bag according to the invention with an applied cover sheet with tear line and protective tape.
• Fig. 4 shows a partial view of a bag according to the invention with an applied cover sheet with two tear lines.
• Fig. 5 shows a section of the bottom of the bag of Fig. 7.
• Fig. 6 shows a sheet-like material for the production of cover sheets according to the invention.

Fig. 1 shows a box valve bag 1 according to the invention in the empty, folded state in plan view. The bag 1 comprises a tubular bag body 1a made of one of the above-mentioned woven or composite materials folded at its two end portions into bottoms 1d, 1e by folding end flaps of the front wall 1b and the back wall 1c with the additional formation of triangular corner folds. The folding of these soils is well known to the skilled person and, for example, in the WO 95/30598 described. When the bag is filled, the trays 1d, 1e assume a rectangular configuration.

The folded bottom 1 d at the first end of the bag body 1 a is connected by hot air welding or gluing, for example with hot melt adhesive, with a cover sheet 10, which will be described with reference to FIGS Fig. 2 is explained in more detail. The folded bottom 1 e at the second end of the bag body is provided with a valve sheet 2 and also connected to a cover sheet 11. The cover sheets 10, 11 have a repeat length L and are preferably made of the same material as the bag body 1a. However, any other of the above-mentioned materials may also be used. The cover sheets 10, 11 may be provided with a printable coating or a printed film.

So that the bag 1 can be opened on the folded bottom 1d, the cover sheet 10 is provided with a tear line 20 defined by cuts, perforations or material weakening. Fig. 2 shows in perspective a portion of the folded topsheet 10 having a tear line 20 formed in a central portion. To protect against accidental tearing of the topsheet at the tear line 20 or to prevent leakage of contents when the tear line 20 is formed by perforations, the Tear line 20 covered by a detachable by means of adhesive strips 23, 24 on the cover sheet 10 adhesive protective tape 22. In order for the guard band 22 to be easily peeled off, it has a free end 22a which does not adhere to the topsheet 10, as in FIG Fig. 3 easy to recognize. The tear line 20 extends over the entire repeat length L.

Fig. 4 shows an embodiment of the bag, in which the on the folded bottom 1 d of the bag body 1 a glued or welded cover sheet 10 has two mutually parallel tear lines 20, 21 which define a tear strip in the cover sheet 10 between each other. The tear lines are formed at one end for ease of gripping than cutting lines 20a, 21a. So that the end region of the tear strip located between the cut lines 20a, 21a does not adhere to the bag body, a separating means 25 is provided. The tear lines 20, 21 do not extend over the entire repeat length L.

As in Fig. 5 In a schematic plan view of the folded bottom 1d, end flaps 1f, 1g of opposite walls 1b, 1c of the bag body 1a are folded together, the end flap 1g of one wall 1c covering the end flaps 1f of the other wall 1b with a covering width x , The configuration of folded bottom 1d and cover sheet 10 is such that a halving line h extending half the distance y between the two tear lines 20, 21 is offset by half the overlapping width x to a center line m of the bottom 1d.

Fig. 6 shows the production of cover sheets 10 of a web-shaped material 30. In the web-shaped material 30 by laser perforation and cutting two parallel tear lines 20, 21 are mounted at a distance y from each other, which are formed in end portions as a continuous section lines 20a, 21a. In the region of the cutting lines 20a, 21a, the material 30 is provided with a release agent 25 which prevents it from sticking to the bag body. The thus prepared sheet material 30 is then cut along transverse cutting lines 31 into individual topsheets 10 in the predefined repeat length L, after forming the tear lines 20, 21 and the release means 25, but before cutting individual topsheets 10, the web material 30 wound onto a roll can be, from which it is unwound from the roll in a bag making machine for cutting cover sheets 10 in the repeat length L.

Claims (14)

A bag (1) having a tubular bag body (1a), wherein the bag body (1a) is folded at at least one end portion to a bottom (1d, 1e) and the folded bottom (1d, 1e) is connected to a cover sheet (10, 11) is, characterized in that the cover sheet (10) has at least one defined by cuts, perforations or material weakening tear line (20, 21). Sack according to claim 1, characterized in that the bottom (1d, 1e) is folded so that end tabs (1f, 1g) of opposed walls (1b, 1c) of the bag body (1a) are folded towards each other, wherein the end flap (1g ) of one wall (1c) covers the end flap (1f) of the other wall (1b) with a covering width (x), and at least one tear line (20, 21) does not overlap the covering end flap (1g). A sack according to claim 1, characterized in that the bottom (1d, 1e) is folded so that end flaps (1f, 1g) of opposed walls (1b, 1c) of the bag body (1a) are folded towards each other, the end flaps (1f , 1g) do not overlap each other, and at least one tear line (20, 21) extends between the two end flaps (1f, 1g). Sack according to one of claims 1 to 3, characterized in that extending the at least one tear line (20, 21) over the entire repeat length (L) of the cover sheet (10). Sack according to one of claims 1 to 3, characterized in that the at least one tear line (20, 21) extends over only a part of the repeat length (L) of the cover sheet (10). Sack according to one of the preceding claims, characterized in that the at least one tear line (20, 21) is covered by a releasably adhering to the cover sheet protective tape (22). Sack according to claim 6, characterized in that the protective tape (22) has a free end (22a) which does not adhere to the cover sheet (10). Sack according to one of the preceding claims, characterized in that two mutually parallel tear lines (20, 21) is provided. Sack according to claim 8, characterized in that the tear lines (20, 21) at one of their ends as cut lines (20a, 21a) are formed. Sack according to claim 8 or 9, characterized in that the bottom (1d, 1e) is folded so that end flaps (1f, 1g) of opposite walls (1b, 1c) of the bag body (1a) are folded towards each other, wherein the end flap (1g) of one wall (1c) covering the end flap (1f) of the other wall (1b) with a covering width (x), characterized in that a halving line running at half the distance (y) between the two tear lines (20, 21) (H) is offset by half the overlap width (x) to a center line (m) of the bag bottom. Sack according to one of the preceding claims, characterized in that the cover sheet (10) is made of a material which is selected from a fabric of plastic tape, wherein the fabric is optionally coated on at least one side with a plastic layer, or a fabric of plastic tape, the coated on at least one side with an OPP film, or connected to a network structure plastic film. Sack according to one of the preceding claims, characterized in that the cover sheet (10) is made of the same material as the bag body (1a). Method for producing a bag (1), comprising: Providing a tubular bag body (1a), Folding a bottom (1d, 1e) at at least one open end of the bag body (1a) by folding end flaps (1f, 1g) of the bag body, Bonding the folded bottom (1d, 1e) to a cover sheet (10), in particular by hot air welding or gluing; characterized in that : in the cover sheet (10) before its connection to the folded bottom (1d, 1e) by means of cutting, perforation or formation of a material weakening at least one tear line (20, 21) is defined. A method according to claim 13, characterized in that the material of the cover sheet (10) is a web material (30) on which at least the first tear line (20, 21) is formed and then by means of cross-sections (31) the cutting of the cover sheets (10 ) takes place in a repeat length (L), preferably the web material (30) after the Forming the at least one tear line (20, 21) is wound on a roll and unwound for cutting in the repeat length of the roll.

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