GB2492901A - Side fold sack with roll bottom - Google Patents

Abstract

A side fold sack 2 made from polyolefin material comprises an area of a tubular segment (1, figure 1), with a front and a rear wall 5, 6 and side walls of the sack 2, whereby the side walls exhibit side folds (4, figure 1), at least one fold of the tube tubular segment 1 made at 180° about an axis essentially transverse to the side folds (4), a bottom area at an end 8 of the area of the tube segment 1, which exhibits a pack 10 comprising at least two layers of the front and rear walls 5, 6, wherein the at least one fold connects the layers 5, 6, and at least two layers 5, 6 are connected by a heat induced bonding process. A tab 9 may also be connected to the sack.

Description

Side Fold Sack With Roll Bottom

Description

The invention relates to sacks from polyolefin material.

Such types of sacks are known. For instance, DE 101 06 289 Al shows such a sack. Among the disadvantages of the sacks fabricated with this type of simple fabrication procedure belongs that the bottom fold opens up particularly then, when the filled sack is stacked and the fold is exposed directly to mechanical load.

Such mechanical load can include that another heavy, filled sack is dragged by this bottom fold, leading to breaking open of the fold. Therefore, the underlying problem of the invention was to propose a sack, in which the bottom area exhibits greater durability. This problem is solved by the features of claim 1.

Among the other advantages of such a sack belongs, that due to the presence of the bottom cover, the filled sack readily assumes a cuboid or a box-shaped form.

Especially firm are sacks made from polyolefin material. For that purpose, the polyolefin fibres are in general textured and oriented mostly monoaxially that is along their longitudinal axis. These fibres are often entwined into flat sheets, from which, tubes are later produced. However, the fibres can be processed directly to round tubes.

Thus, for instance, it is necessary to follow certain processing steps during the welding of these sacks, in order to not lose the firmness of the oriented material again.

All the same, the heat induced seaming procedure in connection with the processing of the sack according to the invention is especially of advantage. Heat induced seaming means here a method of bonding, which requires supply of heat. That is, even a gluing method, which is carried out with temperature-dependent adhesives also belongs to a heat induced bonding method. The same applies to any other type of processing of the extrudates.

Especially advantageous are however the joint welding methods, in which the polyolefin fabric is bonded. Thereby, attention must be paid, as mentioned, that the firmness of the polyolefin fabric does not get impaired due to monoaxial orientation of the macromolecules in polyolefin bands.

A further advantageous possibility in the processing of this material lies in that, the coating, which is often made on polyolefin band tissues, is welded. The fabric is often coated in order, in particular, to the tissue more tight in the filling of pulverisable material.

The sack according to the invention exhibits a bottom fold, which is made about an axis, which is essentially transversal to the axis of the tubular segment or an area of tubular segment. Such a fold or a rolling is not easy to make. Even this fold or the rolling contributes to the subsequent box-like shape of the filled up sack and is therefore of special advantage. With a double fold, not only the stability, but also its tightness of the bottom area is increased considerably and to a surprisingly remarkable extent. The double fold leads to a still stronger bottom, which also supports the box-like shape of the sack especially in conjunction with the label. During the deposition of the label, care must be taken that at least parts of the bottom fold are covered with the label, so that the fold is supported by the label. Depending on the label, however, it can be adequate, if most of the areas remain unsupported and if the labels, for example, in the form of adhesive bands, cover only some parts of the areas of the fold.

The invention belongs to a sack with said bottom area without the label.

In one aspect of the invention a side fold sack from polyolefin material is provided, which exhibits following features: an area of a tubular segment, with front walls and side walls of the sack, whereby the side walls exhibit side folds, at least one fold of the tube tubular segment made at 180° about the axis, which runs essentially transversally to the side folds, a bottom area at an end of the area of the tube segment, which exhibits a pack comprising at least two layers of the front walls, wherein the at least one fold connects the layers, at least two layers are connected by a heat induced bonding process.

Preferably, the pack comprises three layers, wherein all layers are connected to each othei by a heat induced bonding process. In another aspect of the invention the pack comprises three layers, wherein all layers are connected to each other by a heat induced bonding process.

Each layer exhibits a front wall layer and a rear wall layer.

There may be provided a sack comprising coated woven fabric made from oriented polyolefin material.

For example, the connection between the layers made by a heat inducted bonding process may be a sealing connection or a welding connection. In a further aspect of the invention the pack may exhibit a first, a second and a third layer, wherein the first layer is an extension of the front and rear wall without a fold and the second layer is placed between the first and the third layer. Preferably, all layers comprise the same length, which runs essentially parallel to the side folds. Advantageously, the stability and the tidiness of the bottom area, especially of the bottom area at an end of the area of the tube segment can be increased. This bottom area is build by said pack comprising said layers with the same length L. Jternatively, the second layer may comprise a length L, which runs essentially parallel to the side folds, wherein said length L is less than the length L of said first and the third layer. One advantage of this embodiment is that material inside said pack can be saved.

In a one possible embodiment the length L may be between 5mm «= L «= 50mm preferably between 5 and 20 mm.

Further, the pack may comprise two folds, wherein the first fold may connect the first layer with a third layer and the second fold connects the third layer with the second layer. So, said pack comprises a sandwich structure build up by different layers.

In another aspect of the invention a method for fabrication of a side fold sack is provided, in which a front and a rear wall and side walls of the sack are provided, whereby the side walls exhibit side folds, in which segments of a side fold tube are provided and in which in at least one end area of the segment at least one fold of the tubular segment material is made at 1800 about an axis, which is essentially transversal to the side folds, a bottom area at an end of the area of the tube segment is provided, which exhibits a pack comprising at least two layers of the front walls, wherein the at least one fold connects the layers, and at least two layers are connected by a heat induced bonding process.

Preferably, the heat for the heat induced bonding process may be supplied at least in part by means of air.

In a further aspect the invention relates to a tube segment, which may be made from a tube with staggered cuts and/or straight cuts.

In particular, the pack may be formed by a first and/or second fold and a first layer, a second layer and/or a third layer. The double or the triple fold pack leads to a stronger bottom of a side fold sack.

However, it is preferred that the bonding process is started before the layers are folded together. PJternatively, the bonding process may be started afler the layers are folded together. The material of the tubular segment may exhibit a coating, which is applied to the tubular segment, wherein the coating is fused at least partially via the bonding process. Starting the bonding process before the layer are folded together can comprise the advantage, that the material of the sack can be conserved, that means that the material can be treated with care while the bonding process is running. In a one possible embodiment hot air can be induced onto said layers, wherein the coating on said layers is fused. After this heating step said layers are folded together.

In a one embodiment of the invention at least the part of the coating is bonded by melting by means of heat during the fabrication of said side fold sack.

In a further aspect this invention relates to a machine to operate said method for fabrication of a side fold sack, wherein the preferred features of said side fold sack are described above.

Each layer, especially the first layer and/or second layer and/or the third layer exhibit a front wall layer and a rear wall layer.

For the fabrication of the sacks according to the invention, such tubular segments are suitable, which exhibit straight and/or staggered cuts. Sacks according to the invention with straight cuts are especially simple to fabricate. A preferred area of application of the sacks according to the invention lies in the storage and transport of bulk goods, especially of powder-like goods. In this area of its application, sacks, which also exhibit a box-like form, are common, but which are provided with a folded block bottom. Manufacture of such sacks is very elaborate. Common in this area of application are also cross bottom sacks.

In context of the present publication, the heat induced bonding process is used to mean anything, in which material layers are joined with each other. Explicitly mentioned already were the bonding and gluing processes, as well as joints of plastic parts with extrudates. Various materials can be used, depending on the requirements in regard to the stability of the sack. These materials can be the same as or different from the material of the sack or the material of the tubular segment. In case of particularly high loads, olefin fabrics can be used. Again, here too, the modalities involved in making the joints, or the processing conditions recommendable in the processing of polyolefin fabrics, should be adhered to.

Especially advantageous in the fabrication of the seams is, if the outer layer of the tube or the sack material is joined by melting. The heat necessary for that can thereby be supplied by means of heated air, which is blown on the seams to be jointed.

Further exemplary embodiments of the invention follow from the objective

description and the claims.

The individual figures show: FIG. 1 Perspective view of a tube or a segment of the tube in the fabrication of a sack according to the invention.

FIG. 2 Side view of a segment of the tube, in which an end is rolled inwards.

FIG. 3 Top view of an end of a sack according to the invention.

FIG. 4 Side view of an end of a sack according to the invention.

FIG. 5 Mother embodiment of an end of a sack according to the invention.

FIG. 6 The embodiment according to Figure 5 after a first folding.

FIG. 7 The embodiment according to Figure 5 after a second folding.

FIG. 8 A further embodiment of an end of a sack according to the invention.

FIG. 9 The embodiment according to Figure 8 after a first folding.

FIG. 10 A further embodiment of a sack according to the invention.

FIG. 11 The embodiment according to Figure 10 after a first folding.

FIG. 12 The embodiment according to Figure 10 after a second folding.

FIG. 13 Another ombodiment of a sack according to the invention.

FIG. 14 The embodiment according to Figure 13 after a first folding.

FIG. 15 The embodiment according to Figure 13 after a second folding.

FIG. 16 The embodiment according to Figure 9.

FIG. 17 The embodiment according to Figure 7.

FIG. I shows a perspective view of a tube 1 or a tubular segment, which is suitable for the fabrication of a sack 2 according to the invention, especially for all embodiments according to Figure 2 to Figure 17. In the exemplary embodiment, the tube 1 exhibits a longitudinal seam 3. As a rule, the tubes are in general fabricated with such a lengthwise seam from a flat sheet. 1Aiternatively, the tube I can also be of a round shaped material, so that no lengthwise seams are there.

The tube 1 shown in FIG. 1 exhibits side folds 4, made with depth A (see FIG. 3), between the front waIl 5 and the rear wall 6 of the tube 1.

One step in the fabrication process of the sacks 2 according to the invention is illustrated in FIG. 2. About one axis, which runs transversally to the lengthwise seam 3 and lies in the plane parallel to the waIls 5 and 6 of the tube, the lower end of the tube 8 is folded or rolled. Thereby, the folded end 8 of the tube comes to lie against the front wall of the tube 1 or the sack 2 (as shown) or on the rear wall building a sack 10 (not shown). In each, two layers, which are laid one above the other by folding over or rolling, can be connected through an appropriate bonding process.

After the rolling up or folding of the end 8, a label 9 is connected with the folded end 8, and on the wall, on which the fold or the roll lies. In the example shown in FIGS. 3 and 4, the label 9 is connected with the lower end 8 and with the front wall 5. The label 9 extends over the entire length of the sack 2 or the tube 1. In the shown exemplary embodiment, the width B of the label 9 is somewhat smaller than the depth A of the side folds. if the width of the label 9 is smaller or equal to the depth A and the side edge of the label 9 is arranged near the fold or the axis of the roll, then the label 9 lies exclusively at the bottom area of the sack, if it assumes, for example due to filling, a block-like shape. In that case, the bottom is also very resilient against mechanical loads, even when the sack is filled up. In order to improve the firmness further, it can be so provided, that the rolled up or the folded end 8 extends over half of the width B of the label 9.

In the embodiment according to Figure 5 to Figure 7 the side fold sack 2 comprises a bottom area at an endS of the area of the tube segment 1. The end 8 exhibits a pack 10 corn prising three layers 5, 6. First, two folds 11, 12 are made on the tubular segment 1. Then, a heat induced bonding process is started before the third layer 5c, 6c is folded on the second layer Sb, 6b according to Figure 6.

The material of the tubular segment 1 according to all shown embodiments comprises a coating, which can be fused via said bonding process. After inducing heat onto the second layer Sb, 6b and the third layer Sc, 6c according to Figure 5, the third layer 5c, 6c is folded onto the second layer Sb, 6b. In the next step the bonding process is started again inducing heat onto the first layer 5a, 6a and the second layer Sb, 6b. Again, a coating is fused at the first layer 5a, 6a and the second layer Sb, 6b. At the end the package of the second layer 5b, 6b and the third layer Sc, 6c is folded onto the first layer Sa, 6a according to Figure 7.

According to the embodiment of Figure 8 and Figure 9 the pack 10 is formed only by a first layer Sa, 6a and a second layer Sb, 6b. Before the second layer Sb, 6b is folded onto the first layer Sa, 6a, the bonding process is started, which is described in the embodiment of FigureS to Figure 7.

The embodiment according to Figure lOto Figure 12 is essentially the same to the side fold sack 2 according to Figure 5 to Figure 7. The only difference is that a bonding connection is only between the first layer Sa, 6a and the second layer Sb, 6b.

In the embodiment according to Figure 13 to Figure 15 the side folds sack comprises a sack 10, wherein the second layer Sb, 6b comprises a length L, which runs essentially parallel to the side folds 4, wherein said length L is less than the length L of the first layer Sa, 6a and the third layer Sc, 6c. One of the advantages of this embodiment is that material of the tubular segment 1 can be economised. That means that material costs can be reduced without losing essentially the stability and tidiness of the boftom area of the side fold sack 2. In this embodiment only the first layer 5a, 6a and the second layer Sb, 6b are connected by said heat induced bonding process. PJthough, the second layer Sb, 6b can be connected with the third layer 5c, 6c by said heat induced bonding process, which is explicitly not shown.

The length L of said pack 10, especially of the layers 5, 6 is between 5mm «= L «= 20mm. Depending on the application of said sacks the length L can vary.

According to the embodiment of Figure 5 to Figure 7 respectively Figure 10 to Figure 12 the first layer 5a, 6a, the second layer Sb, 6b and the third layer Sc, 6c comprise the same length L. According to all embodiments the second layer 5b, 6b and the third layer Sc, 6c provide characteristics of a sealing and/or an isolation for the side fold sack.

Figure 16 and Figure 17 show explicitly that each layer 5a, 6a, Sb, 6b, 5c, 6c exhibits of a front wall layer 5 and a rear wall layer 6. That means that the pack 10 of Figure 9 comprises four layers, a front wall layer 5a and a rear wall layer 6a of the first layer 5a, 6b and a front wall layer 5b and a rear wall layer 6b of the second layer Sb, 6b. The pack 10 of Figures 7, 12 and 15 comprises six layers, which are explicitly shown in Figure 17.

According to the embodiments of Figure 5 to Figure 15 the pack 10 can comprise a tab 9 according to Figure 3 and Figure 4. So, the tab 9 can connect the front and rear wall 5, 6 and the pack 10. The bottom area of the fold sack 2 can be increased.

List of reference numerals 1 Tube 2 Sack 3 Longitudinal seam 4 Side fold Front wall, layer 5a First layer, front wall layer Sb Second layer, front wall layer Sc Third layer, front wall layer 6 Rear wall, layer 6a First layer, rear wall layer 6b Second layer, rear wall layer 6c Third layer, rear wall layer 7 kds of the fold or the roll 8 Lower end of the tube 9 Label 10 Pack 11 First fold 12 Second fold A Depth of the side folds B Width of the label 9 L Length

Claims (1)

1. <claim-text>Claims 1. Side fold sack (2) from polyolefin material, which exhibits following features: an area of a tubular segment (1), with a front and a rear wall (5, 6) and side walls of the sack (2), whereby the side walls exhibit side folds (4), at least one fold (11, 12) of the tube tubular segment (1) made at 1800 about the axis, which runs essentially transversally to the side folds (4), a bottom area at an end (8) of the area of the tube segment (1), which exhibits a pack (10) comprising at least two layers (5, 6) of the front and rear wall (5, 6), wherein the at least one fold (11, 12) connects the layers (5, 6), at least two layers (5, 6) are connected by a heat induced bonding process.</claim-text> <claim-text>2. Side fold sack (2) according to claim 1, in which the pack (10) comprises three layers (5, 6), wherein at least two layers (5, 6) are connected by a heat induced bonding process.</claim-text> <claim-text>3. Side fold sack (2) according to claim 1 or 2, in which the pack (10) comprises three layers (5, 6), wherein all layers (5, 6) are connected to each other by a heat induced bonding process.</claim-text> <claim-text>4. Side fold sack (2) according to any of the preceding claims, in which the sack (2) comprises coated woven fabric made from oriented polyolefin material.</claim-text> <claim-text>5. Side fold sack (2) according to any of the preceding claims, in which the connection between the layers (5, 6) made by a heat induced bonding process is a sealing connection or a welding connection.</claim-text> <claim-text>6. Side fold sack (2) according to any of the preceding claims, in which the pack (10) exhibits a first (5a, Ga), a second (5b, Gb) and a third layer (Sc, Gc), wherein the first layer (5a, Ga) is an extension of the front walls (5, 6) without a fold (11, 12) and the second layer (Sb, 6b) is placed between the first(Sa, Ga) and the third layer (Sc, 6c).</claim-text> <claim-text>7. Side fold sack (2) according to claim 6, in which all layers (5, 6) comprise the same length L, which runs essentially parallel to the side folds (4).</claim-text> <claim-text>8. Side fold sack (2) according to claim 6, in which the second layer (5b, 6b) comprises a length L, which runs essentially parallel to the side folds (4), wherein said length L is less than the length L of the first (5a, 6a) and the third layer (Sc, 6c).</claim-text> <claim-text>9. Side fold sack (2) according to any of the preceding claims, in which the pack (10) comprises a tab (9) of width (B), which tab (9) is connected with the front and reai wall (5,6) and the pack (10).</claim-text> <claim-text>10. Side fold sack (2) according to any of the preceding claims, in which the length L is between 5mm 5 L 5 50mm, preferably between 5mm S L 5 20mm.</claim-text> <claim-text>11. Side fold sack (2) according to any of the preceding claims, in which the pack (10) comprises two folds (11, 12), wherein the first fold (II) connects the first layer (5a, 6a) with the third layer (5c, 6c) and the second fold (12) connects the third layer (Sc, 6c) with the second layer (Sb, 6b).</claim-text> <claim-text>12. Side fold sack (2) according to any of the preceding claims, in which the first layer (Sa, 6a) and/or the second layer (Sb, 6b) and/or the third layer (Sc, 6c) exhibits a front wall layer (Sa, Sb, Sc) and a rear wall layer (6a, 6b, 6c).</claim-text> <claim-text>13. Method for fabrication of side fold sack (2), in which a front and a rear wall (5, 6) and side walls of the sack (2) are provided, whereby the side walls exhibit side folds (4), in which segments (1) of a side fold tube are provided and in which in at least one end area (8) of the segment (1) at least one fold (11, 12) of the tubular segment (1) material is made at 180° about an axis, which is essentially transversal to the side folds (4), characterized in that a bottom area at an end (8) of the area of the tube segment (1) is provided, which exhibits a pack (10) comprising at least two layers (5, 6) of the front and rear wall (5, 6), wherein the at least one fold (11, 12) connects the layers (5, 6), and at least two layers (5, 6) are connected by a heat induced bonding process.</claim-text> <claim-text>14. Method according to claim 13, characterized in that the heat for the heat induced bonding process is supplied at least in part by means of air.</claim-text> <claim-text>15. Method according to claim 13 or 14, characterized in that the tube segment (1) is made from a tube with staggered cuts and/or straight cuts.</claim-text> <claim-text>16. Method according to any of the preceding claims, in which the pack (10) is formed by a first (11) and/or a second fold (12) and a first layer (5a, 6a), a second layer (Sb, 6b) and/or a third layer (Sc, 6c).</claim-text> <claim-text>17. Method according to any of the preceding claims, in which the bonding process is started before the layers (5, 6) are folded together.</claim-text> <claim-text>18. Method according to any of the preceding claims, in which the bonding process is started after the layers (5, 6) are folded together.</claim-text> <claim-text>19. Method according to any of the preceding claims, in which the material of the tubular segment (1) exhibits a coating, which is applied to the tubular segment (1), wherein the coating is fused at least partially via the bonding process.</claim-text> <claim-text>20. Method according to claim 19, characterized in that at least a part of the coating is bonded by melting by means of heat.</claim-text> <claim-text>21. Machine to operate a method according to the claims 13 to 20, wherein a side fold sack (2) according to the claims Ito 12 is producible.</claim-text>