Foldable paper bag

Abstract

The invention relates to a paper bag (100) whose configuration in the folded state can be described by a front panel and a back panel which are connected to one another along their longitudinal edges and a bottom transverse edge, wherein edge strips (RS) running along the longitudinal edge and adjacent to a central strip (MS) are folded into the interior of the paper bag. By gluing the edge strips (RS) and central strip (MS) in the corner region of the fold, the paper bag (100) assumes an advantageous (e.g., cuboid) configuration when unfolded.

Description

[0001] The invention relates to a foldable paper bag which can be converted from a flat folded state into a three-dimensional unfolded state.

[0002] Paper bags of the type mentioned above are known in various designs. For numerous applications (e.g., shopping bags, compost bags, or the like), paper bags with a so-called block-bottom fold have proven advantageous. By appropriately arranging the fold lines, such paper bags are essentially cuboid-shaped with a rectangular bottom when unfolded.

[0003] Against this background, it was an object of the present invention to provide a foldable paper bag which can be produced easily and preferably in flexible sizes and which, when unfolded, has a configuration which is comfortable for use.

[0004] This object is achieved by a foldable paper bag according to claim 1. Advantageous embodiments are contained in the subclaims.

[0005] As explained above, the foldable paper bag according to the invention has a folded state in which it is essentially flat with the material webs lying flat on top of one another. From this folded state, it can be converted into an unfolded state in which it has a three-dimensional configuration and provides a fillable internal volume.

[0006] The paper bag can be defined by the fact that it has the following components and configuration when folded: - A first panel with two opposite transverse edges and two opposite longitudinal edges, with (at least) one edge strip running along one of the longitudinal edges and with an adjacent central strip, the edge strip being folded over 180° (when the paper bag is folded). For the sake of clarity, this first panel is referred to below as the "front panel" without loss of generality. - A second panel, hereinafter referred to without limitation as the "back panel," which is arranged substantially congruent with the front panel and is connected to it along the longitudinal edges and along one of the transverse edges. The latter transverse edge is hereinafter referred to as the "bottom transverse edge," and typically forms the bottom of the paper bag.

[0007] The paper bag is further characterized in that the edge strip is connected to the central strip in a corner area located on the bottom transverse edge.

[0008] As their name “panel” already suggests, the front panel and the back panel are two flat pieces of material, whereby the designation “front” and “back” is essentially arbitrary.

[0009] As its name suggests, a paper bag is typically made of paper and / or cardboard. For the purposes of this application, however, the term "paper bag" is intended to be understood only as a characteristic of a typical bag design and does not necessarily imply any limitation regarding the material. Accordingly, the "paper bag" can optionally also be made of plastic (PE, PP, etc.), textile, or the like.

[0010] The front panel and / or the back panel typically have a square shape formed by the two long edges and the transverse edges between them. This means that the long and transverse edges are generally straight and meet at sharp corners. However, deviations from this basic shape are optional, for example, with non-straight edges and / or rounded corners.

[0011] The backsheet and frontsheet can be joined along the two longitudinal edges in various ways, for example by gluing. In particular, the connection can also be one-piece along at least one longitudinal edge; this means that the frontsheet and backsheet are made from the same piece of material and the longitudinal edge is simply formed by folding this piece of material. In a typical production process for a paper bag, for example, a tubular body with a longitudinal seam is formed from a wide mother sheet. By flattening the tube, a longitudinal edge with an integral connection of the front and back is then formed, while the other longitudinal edge optionally (depending on the position of the fold) coincides with the longitudinal seam or also has an integral connection of the front and back.

[0012] The connection between the front panel and the back panel along the bottom transverse edge can also be a single piece. Preferably, however, the connection is made by adhesive bonding, whereby the front panel and the back panel can additionally be folded over 180° along the transverse edge (when the paper bag is folded) and placed on top of each other.

[0013] The described foldable paper bag is relatively easy to manufacture, as its basic configuration corresponds to that of a so-called bag with a gusseted bottom. Unlike a bag with a gusseted bottom, however, the connection between the edge strip and the center strip in the corner area creates advantageous behavior of the paper bag when unfolded. In particular, this allows the resulting internal volume to assume a specific configuration, for example, a cuboid shape similar to a bag with a block-bottom fold.

[0014] The connection between the edge strip and the center strip in the corner area goes beyond the existing connection between the edge strip and the center strip at their contact line (as parts of the same front panel). Typically, this additional connection is located (among other things) inside the corner area, is preferably linear or flat, and particularly preferably extends over the entire surface of the corner area. This connection in the corner area can be created in various ways. It is preferably done by gluing, for example with a suitable paper glue. This can be easily applied to the corresponding surfaces during the manufacturing process, which are then folded onto one another to form a connection.

[0015] The shape of the corner region is preferably substantially triangular, corresponding to a corner separated from a rectangle by a straight connecting line between two adjacent sides.

[0016] As already mentioned, the geometry of the front panel and back panel can basically be arbitrary. Preferably, however, the longitudinal edges of the front panel (or corresponding longitudinal edges of the back panel) and / or the transverse edges of the front panel (or corresponding transverse edges of the back panel) are parallel to one another (when the paper bag is folded). If only the longitudinal edges or only the transverse edges are parallel to one another, the corresponding panel has the shape of a trapezoid. If both the longitudinal edges and the transverse edges are parallel to one another, the result is a parallelogram. It is particularly preferred if the parallelogram contains only right angles, i.e., is a rectangle.

[0017] In general, the paper bag could have only a single corner region where the edge strip and the center strip are connected. Preferably, however, there are two, three, or four corner regions where there is a connection between an edge strip and the center strip.

[0018] In a preferred embodiment of the paper bag, the backing panel (when the paper bag is folded) can be configured and arranged essentially as a mirror image of the fronting panel. This means that the backing panel also has a center strip and (at least) one folded edge strip, with the edge strips of the fronting panel and backing panel being connected to one another along their longitudinal edges. In this case, there are (at least) two corner regions (between the edge strip and center strip of the fronting panel, and between the edge strip and center strip of the backing panel), of which at least one (or several or all) can have a connection between the superimposed materials.

[0019] According to a further embodiment of the paper bag, which is preferably present in addition to the mirror symmetry described above, the front panel (in the folded state of the paper bag) is essentially mirror-inverted with respect to a longitudinal axis running through the center strip. This means that the front panel has a second edge strip, which also borders the center strip and is folded over by 180°. If, in this embodiment, the rear panel is simultaneously configured as a mirror image of the front panel as described above, there are thus four edge strips and correspondingly four corner regions in which a connection between the superimposed materials can be present. This is the case in a preferred embodiment of the paper bag.

[0020] In a preferred embodiment, the connection between the front panel and the back panel along the bottom transverse edge is achieved by (when the paper bag is folded) the (superimposed) front panel and back panel being folded over by 180° at the bottom transverse edge. This creates a positive connection between the front panel and back panel, which seals the bottom of the paper bag. To prevent this positive connection from simply opening again, a permanent connection between the materials is preferably also provided, for example, by gluing the folded material layers together.

[0021] According to a further embodiment, an adhesive strip (present in addition to the front panel and back panel) can connect the front panel and back panel along the bottom transverse edge. This type of bottom closure can optionally be combined with the above-described folding of the front panel and back panel to achieve a particularly stable and durable bottom design.

[0022] To assist in unfolding the paper bag into a desired configuration, appropriately pre-prepared crease lines can be provided. In particular, a pre-prepared crease line can run parallel to the bottom transverse edge through the front panel and the back panel. This is referred to below as the "first crease line." When the paper bag is unfolded, the transition between the front or side panels of the paper bag and its bottom runs along this first crease line.

[0023] Additionally or alternatively, a pre-prepared crease line can be provided, running along the corner area of the edge strip. This is referred to below as the "second crease line." When the paper bag is unfolded, sections of the edge strip are typically folded along the second crease line so that they lie on top of each other. The second crease line generally serves primarily to accommodate paper material that is superfluous when the paper bag is unfolded.

[0024] In a paper bag which contains both the first crease line defined above and the second crease line, these two crease lines preferably meet at one point.

[0025] The invention is explained in more detail below with the aid of the attached figures. Herein: Fig. 1 a first (theoretical) manufacturing step of a paper bag in which the front panel and the back panel form a flattened tube; Fig. 2 the second manufacturing step, in which edge strips of the front side web and the back side web are folded inwards; Fig. 3 the third manufacturing step, in which corner areas are glued to a bottom-side transverse edge; Fig. 4 a perspective view of a finished paper bag in an almost fully unfolded state; Fig. 5 the paper bag from Fig. 4 in the fully unfolded state; Fig. Figure 6 shows schematically a first step in the manufacture of a paper bag, according to which two handles are glued to a paper web unwound from a parent roll; Fig. 7 the subsequent manufacturing step in which adhesive is applied to the paper web for the subsequent formation of connected corner areas; Fig. 8 the subsequent manufacturing step in which the paper web is cut to length, rolled into a tube and joined along a longitudinal seam; Fig. 9 the subsequent manufacturing step in which the tubular shape is folded inwards along longitudinal edges and folded over along the bottom transverse edge; Fig. 10 the subsequent manufacturing step in which crease lines are introduced near the bottom; Fig. 11 the final manufacturing step, in which an adhesive strip is glued over the folded base.

[0026] The Fig. Figures 1 to 3 schematically illustrate successive steps for producing a paper bag according to the invention. These steps primarily serve to illustrate the configuration of the paper bag and do not necessarily correspond to a process used in practice. The figures show, on the left, a top view of the resulting paper bag, in the middle, a front view of the resulting paper bag, and on the right, a perspective view of the resulting paper bag.

[0027] According to Fig. 1, the (theoretical) production begins with a square front panel VB and an equally sized square back panel RB lying congruently on top of each other, with the two panels connected along their longitudinal edges LK. As can be seen particularly from the middle view, this configuration essentially corresponds topologically to a flattened tube that is open at the two transverse edges QK. The right transverse edge QK in the figure is referred to below as the "bottom-side transverse edge."

[0028] Furthermore, Fig. 1 it can be seen that the front panel VB (and also the back panel RB) conceptually consists of a wide central strip MS and two edge strips RS adjoining it “above” and “below” parallel to the longitudinal edges LK.

[0029] In Fig. In the next step indicated in Figure 2, the two edge strips RS of the front panel VB and the two edge strips of the back panel RB were each folded inward by 180°, forming a fold facing the inside of the tube. The effective front surfaces of the resulting paper bag are thus formed by the center strips MS, and its side surfaces by the edge strips RS.

[0030] In the next step according to Fig. 3, the edge strips RS are connected to the corresponding adjacent central strips MS in triangular corner areas E at the bottom transverse edge QK, for example by gluing.

[0031] In principle, only one of the four corner areas E could have such a bond (or connection in general). However, preferably, all four corner areas are bonded equally. The adhesive used can be hot melt or a dispersion (cold glue), for example.

[0032] In a final step (not shown), the front panel and the back panel are joined together along the bottom transverse edge (e.g., by a glued seam, by folding and gluing, by an adhesive strip, or the like). The configuration obtained in this way corresponds to the desired configuration of the paper bag to be produced, even if individual production steps or their sequence may typically be different in practice.

[0033] In the Fig. 4 and Fig. Figure 5 shows a paper bag 100 defined in this way in a nearly fully unfolded or fully unfolded state. The designations introduced above reveal the front surfaces of the paper bag 100 in the form of the central strips MS, as well as the laterally adjacent, inward-facing fold of the edge strips RS (of the front panel and back panel). Furthermore, it can be seen that a handle H is glued to each of the central strips MS on the opening side of the paper bag 100.

[0034] The bottom of the paper bag 100 is closed by a US fold of the front panel over the back panel and the bonding of the overlapping material layers. Furthermore, an adhesive strip KS (e.g., made of paper) is bonded over the US fold to provide additional security.

[0035] Furthermore, a first crease line KL1 running parallel to the transverse edge of the base through the center strip MS and edge strip RS of the front side web and the back side web can be seen, which defines the transition between the side or front surfaces and the base surface when the paper bag 100 is unfolded.

[0036] The described paper bag 100 has the advantage, on the one hand, that it can be produced with a similar ease to a bag with a gusseted bottom, namely by folding a tube while folding the opposite side surfaces inward, and then folding and gluing the bottom. However, the additional gluing of corner areas in this process ensures that the configurations in the unfolded state are defined and are assumed almost automatically when the paper bag is filled, with the unfolded paper bag preferably assuming a cuboid configuration similar to a paper bag with a block-bottom fold.

[0037] In the Fig. 6 to 11 schematically show successive steps of a practical industrial manufacturing process of the described paper bag.

[0038] Fig. 6 shows a first manufacturing step, according to which a wide paper web is unwound from a parent roll and then two handles (handles) H and an associated cover sheet (not shown) are glued on.

[0039] Fig. Figure 7 shows the subsequent manufacturing step, in which adhesive K (e.g. hot melt or cold glue) is applied to the paper web with nozzles for the subsequent formation of the base and connected corner areas.

[0040] Fig. Figure 8 shows the subsequent manufacturing step, in which the paper web is cut to repeat and then rolled into a tube and joined (glued) along a longitudinal seam.

[0041] Fig. Figure 9 shows the subsequent manufacturing step, in which the tube is folded inward along the longitudinal edges LK and the bottom is sealed. This is achieved, for example, by a 180° fold US along the bottom transverse edge and bonding the previously applied adhesive.

[0042] Fig. Figure 10 shows the subsequent manufacturing step, in which first crease lines KL1 are introduced parallel to the base transverse edge through the front and side surfaces. These lines will later form the transition between the front and side surfaces on the one hand and the base on the other. Furthermore, second crease lines KL2 are introduced, which run along the glued corner areas and, when unfolded, serve to accommodate excess paper material (base-forming fold).

[0043] Fig.11 shows the final manufacturing step, in which an adhesive strip KS (base sheet) is glued over the folded base.

[0044] In summary, a paper bag is produced whose configuration in the folded state can be described by a front panel and a back panel, which are connected to one another along their longitudinal edges and a bottom transverse edge, with edge strips running along the longitudinal edge and adjacent to a center strip being folded into the interior of the paper bag. By gluing the edge strips and center strip in the bottom corner area of the fold, the paper bag assumes an advantageous (e.g., cuboid) configuration when unfolded.

Claims

[1] A foldable paper bag (100) which, when folded, has: - a front panel (VB) with two opposite transverse edges (QK) and longitudinal edges (LK), an edge strip (RS) running along a longitudinal edge (LK) and an adjacent central strip (MS), the edge strip (RS) being folded over by 180°; - a rear side panel (RB) which is arranged substantially congruent with the front side panel (VB) and is connected to the latter along the longitudinal edges (LK) and a bottom-side transverse edge (QK); wherein the edge strip (RS) is connected to the central strip (MS) in a corner region (E) located on the bottom-side transverse edge (QK). [2] Paper bag (100) according to claim 1, characterized by that the edge strip (RS) in the corner area (E) is glued to the central strip (MS). [3] Paper bag (100) according to at least one of the preceding claims, characterized bythat the longitudinal edges (LK) and / or the transverse edges (QK) are parallel to each other. [4] Paper bag (100) according to at least one of the preceding claims, characterized by that the rear side web (RB) is designed and arranged essentially in a mirror image of the front side web (VB). [5] Paper bag (100) according to at least one of the preceding claims, characterized by that the front side panel (VB) is essentially a mirror image of a longitudinal axis running through the central strip (MS). [6] Paper bag (100) according to at least one of the preceding claims, characterized by that the front panel (VB) and the back panel (RB) are folded over along the bottom transverse edge (QK). [7] Paper bag (100) according to at least one of the preceding claims, characterized bythat an adhesive strip (KS) connects the front panel (VB) and the back panel (RB) at the bottom transverse edge (QK). [8] Paper bag (100) according to at least one of the preceding claims, characterized by that a prepared first crease line (KL1) runs parallel to the bottom transverse edge (QK) through the front side panel (VB) and the back side panel (RB). [9] Paper bag (100) according to at least one of the preceding claims, characterized by that a prepared second fold line (KL2) runs through the edge strip (RS) along the corner area (E). [10] Paper bag (100) according to claims 8 and 9, characterized by that the first bend line (KL1) and the second bend line (KL2) meet at one point.

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