Bag for bulk material

Abstract

Sack (10) for bulk goods made of paper and / or other planar material, with at least one bottom (20) formed in a cross or block bottom fold manner, wherein the bottom fold has two side flaps (25, 26) which are folded to form the bottom around side fold lines extending in the longitudinal direction of the bottom, wherein the side flaps form an overlap when folded, wherein the width of the overlap is a maximum of 10 millimeters, preferably a maximum of 6 millimeters and further preferably a maximum of 4 millimeters.

Description

[0001] The invention relates to a bag for bulk materials such as cement, granules or other powdered or fine-grained building materials, chemicals or foodstuffs with at least one cross or block bottom.

[0002] Such bags are typically made of a flat or web-like material, preferably paper and / or plastic. They are used primarily for the packaging and distribution of powdered or fine-grained bulk materials. Common sizes are 5 kg, 10 kg, and 25 kg.

[0003] To produce such sacks, single- or multi-layer webs of flat material, e.g., paper and / or film webs, are formed into a continuous tube in a so-called tubing machine in a conventional manner and separated into tube pieces of suitable length, from which the sack is ultimately formed, e.g., by means of a cross or block bottom fold. Towards the end of the sack production process, the bottom fold is usually secured with a suitable adhesive. For this purpose, the side flaps of the bottom fold are often folded closed one after the other and glued together at a relatively wide overlap.

[0004] On the one hand, so-called open cross-bottom or block-bottom bags are known. These have a cross-bottom or block-bottom as a standing base and are open at the top for filling the bag. They are only closed after filling, e.g., by sewing and / or gluing. Also known are so-called valve bags, with two opposing cross-bottom or block-bottoms, one of which is designed as a standing base and the other as an opposing valve base. A valve tube is inserted into the bottom of the bag to fill it. This tube is then sealed after filling, e.g., by welding.

[0005] Figure 1This shows the insertion of a cross-bottom according to the state of the art. In the previously known cross-bottom or block-bottom folding, the side flaps are typically folded closed one after the other. When folded, the two side flaps usually have a relatively wide overlap, in which area an adhesive is used to secure the bottom fold.

[0006] A sufficiently wide overlap is required for the mutual bonding of the side flaps. In previously known bags, the width of the overlap can range up to 2.5 - 5 centimeters. This requires sufficiently wide side flaps, which involves corresponding material expenditure. Since these types of bags are produced and sold in large quantities, even small material savings can lead to significant cost advantages. Also previously known are bags in which a gap remains between the closed side flaps so that the closed side flaps do not overlap. However, with such bags, sufficient protection of the contents in the base area is often not guaranteed, especially in multi-layer bags with a film or barrier layer. In addition, the bag base is less stable in the area of ​​the gap.

[0007] Patent GB 716,000 describes a valve sack with a stapled bottom and a narrow overlap, saving material and strengthening the valves, making them less susceptible to accidental opening. Laid-open patent DE 10 2010 026 241 A1 describes a sack with a sack wall designed to open in a humid environment, wherein, in a preferred embodiment, the bottom flaps placed on top of one another to form the bottom fold overlap only slightly. Patent US 5,823,685 describes the closure of a sack for bulk material with folded side flaps that overlap by more than 0.2 inch (5.08 mm). Laid-open patent DE 10 2017 004 268 A1 describes a multi-layer valve sack in which a valve is inserted in the corner fold area of ​​a cross-bottom fold, as well as an inner bar.Patent application EP 3 246 265 A1 describes a valve sack in which a valve flap is inserted in the corner fold of a valve base. The valve flap is held in place by a vent flap located in the opposite corner fold. Utility model DE 20 2018 102 878 U1 discloses a multi-layer cross-bottom or block-bottom sack with an inner bar inserted into the base fold.

[0008] Against this background, it is the object of the present invention to propose a bag in which material can be saved in the base area, while ensuring good protection of the contents and sufficient strength also in the base area.

[0009] According to the invention, the object is achieved by a bag having the features of claim 1. Advantageous embodiments are the subject of the subclaims.

[0010] The bags according to the invention are made of a single- or multi-layer web-like material, in particular paper and / or other flat material, and have at least one bottom formed in a cross-fold or block-fold manner. The corner folds of the bottom fold are located at both ends of the bottom's longitudinal axis, and the side flaps of the bottom fold run essentially parallel to the bottom's longitudinal axis. These side flaps are folded closed around the side fold lines of the bottom fold when the bottom is folded in. The folded side flaps have an overlap. According to the invention, the width of the overlap is a maximum of 10 millimeters, preferably a maximum of 6 millimeters, and more preferably a maximum of 4 millimeters.

[0011] With these overlap widths, the width of the overlap is reduced significantly below the amount normally required for mutual gluing of the side flaps on standard bag manufacturing machines. By reducing the overlap width compared to previously known bags, significant material savings are achieved, which also increases the environmental friendliness of the bags, particularly when these material layers include plastic or other less environmentally friendly materials. The length of the tubular piece from which the bag is made can be significantly reduced, with the same filling volume of the bag, compared to previously known bags with a glued overlap. At the same time, the presence of a narrow overlap still ensures sufficient protection of the contents because a gap between the closed side flaps is avoided. Preferably, the side flaps are not glued to one another in the area of ​​their overlap.The bottom fold can be fixed in any way other than by gluing the overlap of the side flaps, e.g. by gluing a cover sheet.

[0012] Advantageously, the overlap of the side flaps is at least 1 millimeter, preferably at least 2 millimeters, more preferably at least 4 millimeters, and even more preferably at least 6 millimeters. This minimum overlap width better ensures good protection of the contents and good strength of the bag bottom.

[0013] According to the invention, the base of the sack is designed as a valve base into which a valve for filling the sack is incorporated. Advantageously, the valve is designed as a valve tube which is inserted in the area of ​​a corner fold of the base fold. According to the invention, the inner end of the valve tube only reaches as far as the inner edge of the corner fold or just before the inner edge of the corner fold. Due to the smaller overlap of the side flaps and the reduced length of the tube piece from which the sack is formed, the corner folds also require less material. In particular, the corner folds have a smaller width in the direction of the longitudinal axis of the base, i.e. the corner folds extend less far from the ends of the longitudinal axis of the base towards the center of the base. In valve sacks, this width of the corner fold typically has to be overcome by the valve tube so that the filling material can be introduced into the sack as easily as possible.Due to the narrower corner folds, the path traveled by the valve tube in the bags according to the invention is shorter, thus saving valve material. The valve tube is often made of a comparatively expensive material, e.g., a thermal material, to enable the valve to be welded after the bag has been filled. The shortening of the valve tube according to the invention is therefore associated with significant material and cost savings. Accordingly, the base design according to the invention is particularly advantageous for a valve base. Advantageously, the shortening of the valve tube is configured such that the inner end of the valve tube is shortened relative to the inner edge of the corner fold, with this shortening preferably being 3 mm, more preferably 6 mm, and even more preferably 1 cm.

[0014] A valve can be inserted into the still-open base fold as a prefabricated, closed valve tube. Alternatively, it is also possible to insert a so-called valve leaf into the still-open base fold to form the valve, so that the valve leaf is formed into a tube by closing the side flaps. With this design, material savings are also possible because the valve leaf can be made narrower across the base's longitudinal axis.

[0015] In an advantageous embodiment, the bag has two opposing bottoms, designed according to the invention. The side wall of the bag extends between these two bottoms. The inventive design of both bottoms, with a slight overlap of the side flaps, allows for material savings in both bottoms. Particularly advantageously, one of the two bottoms is designed as a valve bottom and the other as a stand-up bottom.

[0016] In another preferred embodiment, the bag is designed as an open cross-bottom or block-bottom bag which is filled via an opening opposite the bottom.

[0017] The bag according to the invention can be designed as a single-layer bag. In a preferred embodiment, the bag is designed as a multi-layer bag, with the material layers preferably consisting of paper and / or coated paper and / or plastic. In multi-layer bags, the material savings in the bottom formation are particularly advantageous.

[0018] In a further preferred embodiment, the bag is constructed in three layers, with the innermost and outermost material layers being made of paper or coated paper, and the intermediate material layer being made of plastic. This allows for particularly good product protection throughout the entire bag, including the base area, while simultaneously ensuring the bag's high strength.

[0019] Advantageously, the bag is made of compostable and / or recyclable materials, in particular paper and / or coated paper.

[0020] In another preferred embodiment, at least one of the bottoms is provided with an inner bar and / or a cover sheet. An inner bar is glued into the still open bottom fold in a known manner. The closed side flaps of the bottom fold are glued over with a cover sheet. The inner bar and / or the cover sheet can increase the protection of the contents in the bottom area and / or fix the bottom fold. In bags with two bottoms, the inner bar and / or cover sheet can be present on one or both bottoms. In the case of bottoms with an inner bar, an opening aid, preferably a tear-off thread, can also be provided in one bottom, preferably in the standing base.

[0021] In a preferred embodiment, the inner bar and / or the cover sheet can be made of paper, particularly plain and / or less durable paper, since the overlap of the side flaps ensures good protection of the contents. In another preferred embodiment, the inner bar and / or the cover sheet are made of a PE-coated paper and / or a film. This allows for even better protection of the contents.

[0022] Another advantageous design is the omission of an inner bar and the gluing of a cover sheet essentially over the entire base, whereby the base fold can be well fixed and the contents can be well protected.

[0023] In another preferred embodiment, the tubular piece from which the bag is formed has a smooth cut at at least one, preferably both, end, in which the cutting line perpendicular to the tubular direction has a continuous course at the ends of the tubular piece. Such a smooth cut allows for a corresponding material savings in the corner folds of the bottom fold, in addition to the side flaps, in a simple manufacturing process.

[0024] Embodiments of the invention are explained in more detail with reference to the following figures. Figure 7a , 7b , 8c and 8b shown. The remaining figures do not depict valve arrangements according to the invention. In detail: Fig. 1: A bag with an unfolded cross bottom according to the state of the art Fig. 2: The open cross bottom of a sack Fig. 3:The open cross bottom of a bag with inner bar Fig. 4: Adding the cross bottom of a sack Fig. 5: The added cross bottom of a sack Fig. 6: The added cross base, covered with a cover sheet Fig. 7: The open cross bottom of a non-inventive bag with valve Fig. 7a: The open cross bottom of a bag according to the invention with a valve tube that reaches to the inner edge of the corner fold Fig. 7b: The open cross bottom of a bag according to the invention with a valve tube that does not reach the inner edge of the corner fold Fig. 8: The open cross bottom of a non-inventive bag with inserted valve label Fig. 8a: The open cross bottom of a bag according to the invention with an inserted valve label that reaches to the inner edge of the corner fold Fig. 8b:The open cross bottom of a bag according to the invention with an inserted valve label that does not reach the inner edge of the corner fold Fig. 9: A paper web section for the production of a sack according to the invention

[0025] Figure 1 shows a sack 1 with a folded-out cross-shaped bottom 3 according to the prior art. To close the bottom, the front side flap 8 is first folded in, followed by the rear side flap 7, and the two side flaps are glued together in their overlapping area with the adhesive strip 9. Conventional sack manufacturing machines require a comparatively wide overlap to apply an adhesive strip in a practical manner.

[0026] Figure 2shows a sack 10 with an open cross-shaped bottom 20. The bottom 20 is divided into two halves by the longitudinal axis 21 of the bottom. Characteristic of the cross-shaped bottom fold are the corner tucks 22 and 23 as well as the side flaps 25 and 26, which are folded around the side fold lines 28 and 29 to close the bottom 20. The side wall 16 of the sack extends downwards from the bottom 20.

[0027] In Figure 3 An inner bar 40 is inserted into the open cross-shaped base 20. The inner bar 40 covers the inner edges of the folded corner folds 22 and 23 and extends from the longitudinal axis 21 of the base to beyond the side fold lines 28 and 29. The inner bar is advantageously glued to the inner edges of the corner folds and the side flaps with a frame adhesive. This ensures good protection of the contents.

[0028] Figure 4shows the closing of the side flaps 25 and 26 of the cross bottom 20 of a bag 10. An inner bar 40 is inserted into the bottom 20. First, the front side flap 26 is closed and then the rear side flap 25 is folded onto it.

[0029] Figure 5shows the folded cross bottom 20 of a sack 10. When folded, the side flaps 25 and 26 only overlap to a small extent. The width of the overlap of the side flaps results from the distance between the edge 35 of the rear side flap 25 and the edge 36 of the front side flap 26. Since the front side flap 26 is folded in first, its edge 36 is covered by the rear side flap 25 which is folded in afterwards. Therefore, the edge 36 of the front side flap 26 is shown in dashed lines, and the uncovered edge 35 of the rear side flap 25 is shown as a solid line. According to the invention, the distance between the edges 35 and 36 or the width of the overlap of the side flaps 25 and 26 is a maximum of 10 millimeters. The overlap is preferably a maximum of 4 millimeters and more advantageously a maximum of 2 millimeters.

[0030] Due to the smaller side flap overlap, the bag can be designed with less material. Due to the small width of the overlap, an adhesive strip cannot be applied properly using the machines commonly used in bag production. Therefore, the invention provides for securing the bottom fold in a different way than by mutually gluing the side flaps together in the overlapping area. For example, the bottom fold can be secured by gluing a cover sheet. This is Figure 6 illustrated. There, the added cross base 20 is covered with a cover sheet 45, which fixes the base fold.

[0031] Figure 7shows a variant of a bag 10 not according to the invention with a still open cross-shaped bottom 20, into which a valve 50 in the form of a prefabricated valve tube is inserted. Due to the narrower design of the side flaps 25 and 26, the corner folds 22 and 23 are also narrower in the longitudinal direction of the bottom. As a result, the valve tube 50 only has to travel a shorter distance to smoothly introduce the contents into the bag. This also allows the valve 50 to be manufactured with less material. Figure 7a shows a variant according to the invention in which the valve tube 50 extends to the inner edge 24 of the corner 22. As a result, somewhat more valve material can be saved in this variant than in the variant according to Figure 7 , in which the valve hose protrudes beyond the inner edge 24 of the corner fold 22. Figure 7bshows a further variant according to the invention, in which the valve tube 50 is shortened at its inner end 54 relative to the inner edge 24 of the corner fold 22. This shortening is preferably 3 mm, more preferably 6 mm and even more preferably 1 cm. Due to the design according to Figure 7b even more valve material can be saved.

[0032] Figure 8 shows a variant of a bag 10 not according to the invention with a still open cross-shaped bottom 20, into which a valve sheet 52 is inserted to form a valve. By closing the side flaps 25 and 26, the valve sheet 52 is formed into a valve tube. In the variant according to Figure 8 the inner edge 56 of the valve label extends slightly further to the center of the bottom of the case than the inner edge of the corner notch 22. Figure 8ashows a variant according to the invention with a valve leaf 52, in which the valve leaf with its inner edge 56 extends to the inner edge 24 of the corner fold 22, so that the valve leaf 52 and the corner fold 22 are flush with one another at the edges 24 and 56. Figure 8b shows a further variant according to the invention, in which the valve tab 52 with its inner edge 56 does not extend to the inner edge 24 of the corner fold 22, so that the valve tube 52 is shortened at its inner end 54 relative to the inner edge 24 of the corner fold 22. Particularly advantageously, the shortening is 3 mm, further advantageously 6 mm, and even more advantageously 1 cm. This allows even more valve material to be saved in this embodiment.

[0033] Figure 9shows a paper web section 12 for producing a sack according to the invention on a continuous paper roll 11. The fold lines of the cross-bottom fold are indicated by dashed lines. The rectangular fields 16 form the side wall 16 of the sack. The paper web sections 12 are cut along the cutting lines 13 and 14 to form individual tube pieces. The cutting lines 13 and 14 accordingly represent the cutting lines of the tube pieces perpendicular to the tube direction. Figure 9 shows cutting lines 13 and 14 formed by a smooth cut, which run continuously perpendicular to the hose direction. With a reduced hose length, a smooth cut can save material both in the area of ​​the side flaps and in the area of ​​the corner folds.

Claims

1. Bag (10) for bulk material of paper and / or other sheet material, with at least one bottom formed in a cross or block bottom folding manner, wherein the bottom fold comprises two side flaps (25, 26) which are folded about side fold lines (28, 29) extending in the longitudinal direction of the bottom for bottom formation, wherein the side flaps form an overlap in the closed state, wherein the width of the overlap is at most 10 millimeters, wherein the bottom is formed as a valve bottom in which a valve (50, 52) for filling the bag is incorporated, wherein the valve (50, 52) is inserted in the region of a corner turn-in (22, 23) of the bottom fold, characterized in that an inner end (54, 56) of the valve extends up to the inner edge (24) of the corner turn-in or is shortened relative to the inner edge (24) of the corner turn-in.

2. Bag according to claim 1, characterized in that the width of the overlap is a maximum of 10 millimeters, preferably a maximum of 6 millimeters and further preferably a maximum of 4 millimeters.

3. Bag according to claim 1 or 2, characterized in that the width of the overlap is at least 1 millimeter, preferably at least 2 millimeters and further preferably at least 4 millimeters.

4. Bag according to any of the preceding claims, characterized in that the shortening is 3 mm, preferably 6 mm and still further preferably 1 cm.

5. Bag according to any of the preceding claims, characterized in that the valve is formed as a valve tube (50) and / or as a valve patch (52).

6. Bag according to any one of the preceding claims, comprising two opposite bottoms formed according to claim 1 or 2, between which the side wall (16) of the bag extends.

7. Bag according to claim 1 or 2, characterized in that the bag is designed as an open cross-bottom or block-bottom bag.

8. Bag according to one of the preceding claims, characterized in that the bag is designed as a multilayer bag, wherein the material layers preferably consist of paper and / or coated paper and / or plastic.

9. Bag according to any one of the preceding claims, characterized in that the bag is formed of three layers, wherein the innermost and the outermost material layer are formed of paper and intermediate material layer is formed of plastic film.

10. Bag according to any of the preceding claims, characterized in that the bag is formed of compostable and / or recyclable materials, in particular paper and / or coated paper.

11. Bag according to any one of the preceding claims, characterized in that at least one of the bottoms is provided with an inner latch (40) and / or a cover sheet (45).

12. Bag according to the preceding claim, characterized in that the inner latch comprises uncoated paper, PE-coated paper and / or film.

13. Bag according to one of the preceding claims, characterized in that the bag is formed from a piece of tubing which has a smooth cut at at least one, preferably both ends (13, 14).

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