Method and device for connecting pieces made of woven plastic-strip fabric, sacks manufactured therefrom, devices for manufacturing and closing sacks, and sets consisting of pieces made of woven plastic-strip fabric and connection devices

Abstract

The method for connecting pieces made of woven plastic-strip fabric comprises providing a first woven plastic-strip fabric (3) the strips of which contain a first thermoplastic polymer, wherein on a first surface (3a) of the first woven plastic-strip fabric (3) discrete particles (7), which contain a third thermoplastic polymer, are fixed, and providing a second woven plastic-strip fabric (14) the strips of which contain a second thermoplastic polymer, wherein the second woven plastic-strip fabric (14) is provided, on a surface, with a weldable coating (15), which contains a fourth thermoplastic polymer. The discrete particles (7) and the weldable coating (15) are heated above the softening point of the third and the fourth thermoplastic polymer. The discrete particles (7) are brought into contact with the weldable coating (15), and the first and the second woven plastic-strip fabrics (3, 14) are then pressed against one another, as a result of which the discrete particles (7) of the first woven plastic-strip fabric (3) and the weldable coating (15) of the second woven plastic-strip fabric (14) are connected to one another.

Description

[0001] Method and device for joining pieces of plastic tape fabric, bags made therewith, devices for producing and closing bags, and sets of pieces of plastic tape fabric and joining devices

[0002] The invention relates to a method and a device for joining pieces of plastic ribbon fabric, to bags produced therewith, and to devices for producing and closing bags.

[0003] The invention further relates to sets of pieces of first and second plastic ribbon fabrics and at least one device for connecting the first and second plastic ribbon fabrics.

[0004] In the packaging industry, the task of joining pieces of plastic tape fabric together often arises, for example, in the manufacture and sealing of plastic tape fabric bags. The term "piece," as used herein, also includes the synonymous terms "part, section, element." In particular, pieces of plastic tape fabric include bag bodies, top sheets, valve sheets, and bag sealing tapes, as well as packaging.

[0005] Document US 5885679A1 provides a joining structure for a waterproof fabric consisting of a base fabric with a soft (elastomeric) resin film adhered thereto. The joining structure is formed in a welt seam, into which a hot-melt adhesive layer is inserted as part of the intermediate layers of the structure.

[0006] Document US 4190010 A1 describes a method for forming a seam that joins two edges of a piece of fabric coated on one side with a waterproof, radio-frequency weldable plastic material, creating a waterproof seam. In the method, the two edges are positioned with the coated sides facing outward. A binding strip is placed over the coated sides, with the side of the binding strip in contact with the coated sides itself coated with a radio-frequency activated material. A radio-frequency field is applied to the seam to weld adjacent coated surfaces of the binding strip and the fabric together. US 2019 / 0032286 A1 presents a fully recyclable artificial turf that solves the problem of joining the existing artificial turf.

[0007] DE 4240285 A1 describes a device for concealing a pot or household sponge.

[0008] Due to their high strength and moisture resistance, sacks made of plastic tape fabric, particularly polyolefin or polyester tape fabric, have established themselves as a versatile packaging material. Typically, the starting material for such sacks is a tubular fabric, particularly a tubular circular fabric, or a flat fabric joined to form a tube, with at least one open end of the tubular fabric being sealed.

[0009] For the transport of loose material, such as powdery or granular material, so-called box bags made of plastic tape fabric are usually used. These bags are closed on both sides by a bag bottom formed by folding the open ends of the tubular bag body. To increase the strength of the bag bottom, a cover sheet made of plastic tape fabric can be applied to the bottom. For filling box bags closed on both sides, valves formed by valve blades have proven effective, as this ensures that the valve closes automatically after the bag is filled. The valve blade is inserted into the bag bottom when the bag bottom is folded and connected to it. Box-shaped bags closed on both sides with a valve - also called box-valve bags - and their production are known, for example, from patent EP 0 758 992 B1.

[0010] Another type of bag for packaging loose material is the pillow-shaped bag. The open ends of the tubular plastic tape fabric forming the bag body are closed by sewing and / or by attaching a sealing tape. The sealing tape is bent over into a U- or V-shape along its length, extends across the open edge of the tubular bag body, has a sealing layer on the surface facing the plastic tape fabric, and is fully bonded to the plastic tape fabric of the bag body by welding the sealing layer. Closing the open ends by sewing results in partial weakening of the fabric in the area of ​​the seam. In addition, sewing causes the bag to leak at the seams, allowing the filling material, particularly if it is powdery, to escape from the bag interior.Therefore, to reinforce the bag in the area of ​​the seam to seal against leakage of the filling material, a sealing tape (also called sealing tape) is used which - as described above - is bent over its length in a U- or V-shape, extends across the edge of the tubular bag body and over the seam, has a sealing layer on its surface facing the plastic ribbon fabric of the bag body and is fully connected to the plastic ribbon fabric of the bag body by welding the sealing layer.

[0011] Mixed forms of box bags and pillow bags are also known, in which the lower end of the tubular plastic ribbon fabric is formed into a bag bottom, and the upper end is closed after the bag has been filled, as in a pillow bag, by sewing and / or sealing using a sealing tape.

[0012] Furthermore, pillow bags can be provided with side folds.

[0013] Flat plastic ribbon fabric made from stretched plastic ribbons exhibits superior strength across its surface, resulting from the stretching of the plastic ribbons and the resulting alignment of the molecular chains within the plastic ribbons. However, directly welding pieces of this plastic ribbon fabric together is difficult and results in a loss of alignment of the molecular chains within the plastic ribbons. For this reason, the surfaces facing each other when joining the pieces of plastic ribbon fabric are fully weldable coatings. These coatings are softened by heat during the bonding process. The pieces of plastic ribbon fabric are then pressed against each other, intimately bonding the softened, weldable coatings and, after cooling, creating a strong bond between the pieces of plastic ribbon fabric.

[0014] The disadvantage of this procedure, however, is that a separate coating process must be carried out for each of the facing surfaces of the pieces of plastic tape fabric to be joined to produce the weldable coatings. Another serious disadvantage is the high material consumption required to produce the weldable coatings. To reduce this material consumption, attempts have already been made to apply a weldable coating to only one surface of the plastic tape fabric to be joined. However, this resulted in reduced strength of the joint produced in this way, which is due to the fact that plastic tape fabric does not have a flat surface and has gaps between the woven plastic tapes.In addition, such a joining process usually affects the alignment of the molecular chains in the plastic ribbons because the plastic ribbons partially melt during the joining process.

[0015] There is therefore still a need for a method for joining pieces of plastic ribbon fabric which can eliminate a coating process, achieve a reduction in the material required to produce weldable coatings, do not impair the alignment of the molecular chains in the stretched plastic ribbons, and yet still provide sufficient strength for joining the pieces of the plastic ribbon fabric.

[0016] The present invention solves the problems mentioned by a method for joining pieces of plastic tape fabric having the features of claim 1 and by providing bags made of plastic tape fabric in which pieces of plastic tape fabric forming the bag are joined together by the joining method according to the invention.

[0017] The invention for joining pieces of plastic ribbon fabric comprises providing a first plastic ribbon fabric, the ribbons of which contain a first thermoplastic polymer, wherein discrete particles containing a third thermoplastic polymer are fixed to a first surface of the first plastic ribbon fabric, providing a second plastic ribbon fabric, the ribbons of which contain a second thermoplastic polymer, wherein the second plastic ribbon fabric is provided on one of its two opposite surfaces with a weldable coating containing a fourth thermoplastic polymer, heating the discrete particles of the first plastic ribbon fabric and the weldable coating of the second plastic ribbon fabric above the softening temperature of the third and fourth thermoplastic polymers,bringing the discrete particles of the first plastic ribbon fabric into contact with the weldable coating of the second plastic ribbon fabric, pressing the first and second plastic ribbon fabrics against each other, thereby bonding the discrete particles of the first plastic ribbon fabric and the weldable coating of the second plastic ribbon fabric, and optionally cooling the bonded pieces of the first and second plastic ribbon fabric.

[0018] The device according to the invention comprises a first supply unit for supplying the first plastic ribbon fabric, which is preferably designed as a roller, and a second supply unit for supplying the second plastic ribbon fabric, which is preferably designed as a conveyor device, in particular as a conveyor belt or conveyor cylinder.

[0019] Furthermore, the device has a heating unit, which preferably comprises an air pump for generating an air flow, a heating device for heating the air flow, and an air nozzle through which the heated air flow can be directed into a gap between the first plastic ribbon fabric and the second plastic ribbon fabric.

[0020] By means of the method and device according to the invention, the first and second plastic ribbon fabrics are connected to one another by a plurality of discrete connection points made of particles containing the third thermoplastic polymer. The connection points are distributed as evenly as possible and extend essentially over the entire connecting surface between the first and second plastic ribbon fabrics, thus creating the overall effect of a "full-surface" connection with homogeneous bonding properties while significantly reducing material consumption. The connection points do not impair the alignment of the molecular chains in the stretched plastic ribbons and provide sufficient strength for the connection between the pieces of plastic ribbon fabric.

[0021] In a preferred embodiment of the invention, the first plastic ribbon fabric is provided on a second surface, which is opposite the first surface, with an optionally printed plastic coating or a laminated plastic film.

[0022] It has proven useful if the first and / or second thermoplastic polymer is selected from PP, HDPE or PET. The first and second thermoplastic polymers can be selected from the same material or from different materials. It should be mentioned that the ribbons of the plastic ribbon fabric can also contain additives for special properties, such as color or UV protection, or - in the case of PET - to reduce the tendency to splice. The third and / or fourth thermoplastic polymer is preferably selected from: PET, PP, PE, or a co- or terpolymer which contains two or three of the following monomers: ethylene, propylene, vinyl acetate, alkyl acrylate, maleic anhydride, alpha olefin. The third and fourth thermoplastic polymers can be selected from the same material or from different materials.

[0023] In a further preferred embodiment of the invention, the second plastic ribbon fabric is provided on its surface opposite the weldable coating with an optionally printed coating or a laminated plastic film.

[0024] In one preferred embodiment of the invention, particularly for the production of bag bodies, the first and second plastic ribbon fabrics form longitudinal sections of a flat, web-like substrate, wherein the flat, web-like substrate is shaped into a tube such that the discrete particles of the first plastic ribbon fabric are brought into contact with the weldable coating of the second plastic ribbon fabric. The substrate expediently has a base layer made of a plastic ribbon fabric, wherein in this embodiment the first and second plastic ribbon fabrics together form the base layer made of the plastic ribbon fabric. The discrete particles of the first plastic ribbon fabric are arranged in an edge section of the flat, web-like substrate.

[0025] In a further preferred embodiment, the particles containing the third thermoplastic polymer have an average particle size of less than or equal to 1000 pm.

[0026] Low material consumption with sufficient bond strength is achieved when the particles have a surface weight between 1 g and 20 g per m 2 , preferably between 3 g and 5 g per m 2 , are applied to the first plastic tape fabric. This basis weight range is far below the basis weights of conventional joints using full-surface weldable coatings. The joint strength can be adjusted by selecting an appropriate basis weight within the specified range.

[0027] In one embodiment of the invention, it is provided that the particles are applied to the first plastic ribbon fabric by providing a release surface, providing and arranging a plurality of the discrete particles on the release surface, wherein the release surface has a temperature that is above a softening temperature of the third thermoplastic polymer, heating the particles arranged on the release surface above the softening temperature of the third thermoplastic polymer, bringing the first surface of the first plastic ribbon fabric into contact with the release surface and the softened particles arranged thereon, so that the particles adhere to the first surface of the first plastic ribbon fabric, subsequently removing the first surface of the first plastic ribbon fabric with the particles adhering thereto from the release surface,and optionally cooling the particles adhering to the first surface of the first plastic ribbon fabric below the softening temperature of the third thermoplastic polymer.

[0028] Document EP 3 463 805 B1 describes slip-resistant, flexible materials and methods for their production and use. In these methods, individual thermoplastic particles heated to a tacky state are applied to the surface of a thermoplastic, flexible carrier that can be used as a slip-resistant, flexible packaging material. This document discloses process steps that are also used in the above-described embodiment of the invention.

[0029] The method according to the invention for joining pieces of plastic ribbon fabric is ideally suited for the production of bags.

[0030] In one embodiment, a sack is provided with a sack body, wherein a bottom is formed at at least one end of the sack body by folding the ends of the sack body, and the bottom is connected to at least one cover sheet. The sack body and the cover sheet are connected to one another according to the method according to the invention, wherein the cover sheet forms the first plastic ribbon fabric and the sack body forms the second plastic ribbon fabric, or wherein the cover sheet forms the second plastic ribbon fabric and the sack body forms the first plastic ribbon fabric. The first embodiment represents the normal case; the second embodiment is preferable when the sack body is to be made non-slip by the application of the discrete particles.

[0031] One embodiment of the invention comprises a set with

[0032] - pieces of a first plastic ribbon fabric, the ribbons of which contain a first thermoplastic polymer, wherein discrete particles containing a third thermoplastic polymer are fixed to a first surface of the first plastic ribbon fabric;

[0033] - pieces of a second plastic ribbon fabric, the ribbons of which contain a second thermoplastic polymer, the second plastic ribbon fabric being provided on one of its two opposite surfaces with a weldable coating containing a fourth thermoplastic polymer; and

[0034] - a device for connecting pieces of the first plastic ribbon fabric to pieces of the second plastic ribbon fabric.

[0035] The device comprises a first supply unit for supplying the first plastic ribbon fabric, a second supply unit for supplying the second plastic ribbon fabric, and a heating unit, wherein the first supply unit and the second supply unit are configured to supply the first plastic ribbon fabric and the second plastic ribbon fabric such that the first surface of the first plastic ribbon fabric and the weldable coating of the second plastic ribbon fabric face each other, wherein the heating unit is configured to heat the discrete particles of the first plastic ribbon fabric and the weldable coating of the second plastic ribbon fabric above the softening temperature of the third and fourth thermoplastic polymers.

[0036] The first and second delivery units are configured to bring the heated discrete particles of the first plastic ribbon fabric and the heated weldable coating of the second plastic ribbon fabric into contact with each other and to press the first and second plastic ribbon fabric against each other so that the discrete particles of the first plastic ribbon fabric and the weldable coating of the second plastic ribbon fabric bond together.

[0037] In the set, the first supply unit can be designed as a roller and the second supply unit can be designed as a conveyor device, preferably as a conveyor belt or conveyor cylinder.

[0038] In a preferred embodiment of the set, the heating unit comprises an air pump for generating an air flow, a heating device for heating the air flow, and an air nozzle through which the heated air flow can be directed into a gap between the first plastic ribbon fabric and the second plastic ribbon fabric. In a further embodiment, a bag is provided with a bag body, wherein a bottom is formed at at least one end of the bag body by folding the ends of the bag body, and the bottom is provided with a valve leaf. The bag body and the valve leaf are connected to one another according to the method according to the invention, wherein the valve leaf forms the first plastic ribbon fabric and the bag body forms the second plastic ribbon fabric, or wherein the valve leaf forms the second plastic ribbon fabric and the bag body forms the first plastic ribbon fabric.The first embodiment represents the normal case; the second embodiment is preferable if the bag body is to be made non-slip by applying the discrete particles.

[0039] In yet another embodiment, a sack is provided with a sack body with or without side gussets and with an open end, wherein the open end is closed by a sealing tape and optionally sewn. The sack body and the sealing tape are joined together according to the method of the invention, wherein the sealing tape forms the first plastic tape fabric and the sack body forms the second plastic tape fabric, or wherein the sealing tape forms the second plastic tape fabric and the sack body forms the first plastic tape fabric. The former embodiment represents the normal case; the latter embodiment is preferable when the sack body is to be made non-slip by the application of the discrete particles.

[0040] An embodiment of the set according to the invention, in which the pieces of the first plastic ribbon fabric form sealing bands and the pieces of the second plastic ribbon fabric form tubular bag bodies equipped with or without side folds, or in which the pieces of the second plastic ribbon fabric form the sealing bands and the pieces of the first plastic ribbon fabric form the tubular bag bodies, further comprises

[0041] - a conveyor device for transporting the bag bodies lying flat in the transverse direction, and

[0042] - a connecting unit arranged on the conveyor device in the region of the open ends of the bag bodies, wherein the connecting unit has a device for feeding the sealing tape and is designed to arrange the sealing tape in a U-shaped or V-shaped manner, encompassing the open end of each bag body, wherein the connecting unit has the connecting device for connecting the sealing tape to the bag body by applying heat and pressure. The invention is explained in more detail below with reference to the drawings and non-limiting exemplary embodiments.

[0043] Fig. 1 shows schematically an apparatus for producing a flexible web-shaped substrate material for use in the method according to the invention.

[0044] Fig. 2 shows a substrate material made of a plastic ribbon fabric with a plurality of discrete polymer particles on its surface and a plastic coating on its other surface for use in the method according to the invention.

[0045] Fig. 3 shows a device for carrying out the connection method according to the invention.

[0046] Fig. 4 shows a substrate with a plastic ribbon fabric that can be connected to a tube.

[0047] Fig. 5a, 5b, 5c show a bag according to the invention.

[0048] Fig. 6 shows a device for producing the bag of Fig. 5a, 5b, 5c.

[0049] Fig. 7 shows a device for producing or closing another bag according to the invention.

[0050] First, the production of a substrate material 2 shown in cross-section in Fig. 2 is explained with reference to the schematic representation in Fig. 1, which has a first plastic ribbon fabric 3 as the carrier material, the ribbons of which are made of stretched plastic and contain a first thermoplastic polymer, wherein discrete particles 7 containing a third thermoplastic polymer are fixed to a first surface 3a of the first plastic ribbon fabric 3. On a second surface 3b of the first plastic ribbon fabric 3, which lies opposite the first surface 3a, the first plastic ribbon fabric 3 is provided with a plastic coating 4, which is applied to the second surface 3b, for example, using a slot die 11 and can then be printed. In this example, the first thermoplastic polymer is selected from PP, HDPE or PET.The third thermoplastic polymer is selected from PET, PP, PE, or a co- or terpolymer containing two or three of the following monomers: ethylene, propylene, vinyl acetate, alkyl acrylate, maleic anhydride, alpha-olefin.

[0051] Fig. 1 schematically shows a device 1 for producing the flexible web-shaped substrate material 2. The web-shaped first plastic ribbon fabric 3 is fed to this device 1 from a roll on which it is wound by means of a driven pair of rollers 5 and reaches a release surface 6 of the device 1. The release surface 6 is designed as a heated endless conveyor belt circulating around rollers, which is preferably equipped with a surface made of polytetrafluoroethylene (PTFE), known under the brand name "Teflon", or a material with similar properties to PTFE. PTFE has high chemical and thermal resistance, a low coefficient of friction, and is anti-adhesive. Discrete particles 7 containing the third thermoplastic polymer are applied from a container 8, for example by means of a spreader roller, in a large number and in as even a distribution as possible onto the release surface 6.The heated release surface 6 has a temperature that lies above a softening temperature of the third thermoplastic polymer. The particles 7 heat up on the release surface above the softening temperature of the third thermoplastic polymer and, in the softened state, adhere sufficiently to the release surface 6 so that they do not fall off the release surface 6 even during their transport on the rotating release surface 6. The first plastic ribbon fabric 3 and the release surface 6 pass through a pair of rollers 9 so that the particles 7 on the release surface 6 face the first surface 3a of the first plastic ribbon fabric 3. The pair of rollers 9 presses the particles 7 against the first surface 3a of the first plastic ribbon fabric 3, whereby the softened particles 7 adhere to the first surface 3a of the first plastic ribbon fabric 3.Subsequently, the first surface 3a of the first plastic ribbon fabric 3, with the particles 7 transferred thereto, moves away from the release surface 6, which is thus ready for the renewed application of particles 7. The first surface 3a of the first plastic ribbon fabric 3 is now cooled until the particles 7 have a temperature below the softening temperature of the third polymer. In this exemplary embodiment, cooling is carried out actively by means of a cooling device 10. Depending on the ambient temperature, transport speed, and transport length of the first plastic ribbon fabric 3, passive cooling, e.g., by ambient air, can also be provided, in which the particles 7 are allowed to cool on the first plastic ribbon fabric 3.

[0052] As an alternative to applying the printable plastic coating 4 to the second surface 3b of the plastic ribbon fabric 3, a plastic ribbon fabric 3 which is already provided on the second surface 3b with the plastic coating 4 or a laminated plastic film can be provided as a roll material.

[0053] The process of bonding the substrate material 2 to a second plastic ribbon fabric 14, which is provided with a weldable coating 15 over its entire surface on one of its surfaces, is explained using the device 20 schematically shown in Fig. 3. The second plastic ribbon fabric 14 is woven from stretched plastic ribbons containing a second thermoplastic polymer. The weldable coating 15 contains a fourth thermoplastic polymer. In this example, the second thermoplastic polymer is selected from PP, HDPE, or PET. The fourth thermoplastic polymer is selected from PET, PP, PE, or a co- or terpolymer containing two or three of the following monomers: ethylene, propylene, vinyl acetate, alkyl acrylate, maleic anhydride, alpha-olefin. The weldable coating 15 can be applied to the second plastic ribbon fabric 14, for example, using slot dies.

[0054] With reference to the device 20 shown in Fig. 3, the second plastic ribbon fabric 14 is fed onto a first supply unit designed as a conveyor device 22, such that the second plastic ribbon fabric rests against the conveyor device 22 and its weldable coating 15 is exposed, facing away from the conveyor device 22. The second plastic ribbon fabric 14 can be a flat material or a tubular material and, for example, form a sack body. If the second plastic ribbon fabric 14 is a tubular material, it can optionally be provided with side folds. The substrate material 2 is fed via a second supply unit, which is designed as a roller 21, in such a way that the particles 7 of the first plastic ribbon fabric 3 face the weldable coating 15 of the second plastic ribbon fabric 14 and the optional plastic coating 4 rests against the surface of the roller 21.The first plastic ribbon fabric 3 or the substrate material 2 produced therefrom can, for example, form a cover sheet for a bag bottom, a valve sheet for a bag, or a sealing tape or sealing band for a bag. The conveyor device 22 and the roller 21 are spaced so closely apart that the substrate material 2 and the second plastic ribbon fabric 14 with the weldable coating 15 are pressed against one another. If the conveyor device 22 is designed as a conveyor belt, a counter-roller can be arranged on the side of the conveyor belt facing away from the roller 21 to generate the necessary pressing pressure, supporting the conveyor belt. The weldable coating 15 and the particles 7 are heated above their softening temperature by a heating unit. For this purpose, an air pump 23 is provided, the air flow generated by the pump being heated by a heating device 24.The heated air stream is then directed through an air nozzle 25 into the gap between the substrate material 2 and the second plastic ribbon fabric 14. The heated air stream softens the particles 7 of the first plastic ribbon fabric 3 and the weldable coating 15 of the second plastic ribbon fabric 14. When the particles 7 are brought into contact with the weldable coating 15 and pressed against each other, the discrete particles 7 and the flat weldable coating 15 bond together to form a high-strength joint. Optionally, after pressing against each other, the joined pieces of the first and second plastic ribbon fabrics 3, 14 are cooled.

[0055] Fig. 4 shows the joining of a flat, web-shaped substrate 16 to form a tube. Opposing longitudinal sections of the substrate 16 are formed by the first plastic ribbon fabric 3 and the second plastic ribbon fabric 14. Strictly speaking, the substrate 16 has a plastic ribbon fabric that forms both the first plastic ribbon fabric 3 and the second plastic ribbon fabric 14. One surface of the substrate 16 is provided with the discrete particles 7. The surface of the substrate 16 opposite the surface with the particles 7 has the weldable layer 15. The particles 7 are exposed on one longitudinal section of the substrate 16. The remaining area is provided with a plastic fleece 17 that is bonded to the particles 7.The substrate 16 is formed into a tube such that the discrete particles 7 are brought into contact with the weldable coating 15, heated above the softening temperature and pressed against each other so that a strong bond is formed.

[0056] Figures 5a, 5b, and 5c show a sack 30 according to the invention in side view, front view, and in a cross-section through its closed upper end. The sack 30 has a sack body 31 with side gussets 32 and an upper end, wherein the upper end is closed by a sealing tape 33 and sewn by an optional seam 34. The sealing tape 33 is formed by a substrate material 2 comprising the first plastic tape fabric 3, the discrete particles 7 applied thereto, and a plastic coating 4, as also shown in Fig. 2. The sack body 31 is formed by the second plastic tape fabric 14 with the weldable coating 15. The sack body 31 and the sealing tape 33 are connected to one another by means of the connection method explained above.

[0057] Fig. 6 schematically shows the device for closing the open end of the bag 30 with side gussets 32. The tubular bag bodies 31 are conveyed lying flat in the transverse direction on a conveyor device 35. A connecting unit 36 ​​is arranged at the open ends of the bag bodies 31. This connecting unit 36 ​​has a device for feeding the sealing tape 33. In the connecting unit 36, the sealing tape 33 is arranged in a U-shape or V-shape around the open end of each bag body 31 and is welded to the weldable coating 15 of the bag body 31 by applying heat and pressure, for which purpose a connecting device 20 according to Fig. 3 is provided.

[0058] Fig. 7 shows schematically sacks 40 according to the invention designed as box valve sacks and their production. Each sack 40 has a sack body 41, at the ends of which bottoms 42, 43 are formed by folding the sack body 41. The bottom 42 is connected to a cover sheet 44 and to a valve sheet 47. The bottom 43 is connected, for example, to two cover sheets 45, 46. The cover sheets 44, 45, 46 and the valve sheet 47 are formed from a substrate material 2 made of the first plastic ribbon fabric 3, the discrete particles 7 applied thereto and a plastic coating 4, as shown in Fig. 2. The sack body 41 is formed from the second plastic ribbon fabric 14 with the weldable coating 15, as shown in Fig. 2. The connection of the substrate material 2, from which the cover sheets 44, 45, 46 andThe joining of the first plastic ribbon fabric 3, which may consist of the valve sheet 47, with the weldable coating 15 of the second plastic ribbon fabric 14 of the bag body 41 can be carried out using the device 20 shown in Fig. 3. Individual units of the device for producing the bag 40 are shown schematically in Fig. 7 and will now be explained. In an alternative embodiment not shown in the drawing, in which the bag bodies 41 are to be made non-slip by applying the discrete particles 7, the first plastic ribbon fabric 3 forms the bag body 41, and the second plastic ribbon fabric 14 forms the cover sheets 44, 45, 46 and the valve sheet 47.

[0059] The flat-lying tubular bag bodies 41 are transported transversely from bottom to top in the drawing on a conveyor device (not shown).

[0060] Unit A shows the folding of bottoms 42, 43 at the open ends of the tubular bag body 41 by pulling the open ends apart and folding over portions of the bag body 41 to form flaps. The bag body 41 can be made of a circularly woven tube or a flat fabric whose longitudinal ends are joined together, as shown in Fig. 4.

[0061] Unit B shows the insertion of a valve leaf 47 into the base 42 and the connection of the valve leaf 47 to the second plastic ribbon fabric 14 or its weldable coating 15 of the bag body 41 according to the connection method according to the invention.

[0062] Unit C shows the application of a first cover sheet 45 into a first region of the bag bottom 43 and the connection of the first cover sheet 45 to the second plastic ribbon fabric 14 or its weldable coating 15 of the bag body 41 according to the connection method according to the invention.

[0063] Unit D shows the application of a second cover sheet 46 to a second region of the bag bottom 43 and the bonding of the second cover sheet 46 to the second plastic ribbon fabric 14 or its weldable coating 15 of the bag body 41 according to the bonding method according to the invention. The density of the particles 7 on the first plastic ribbon fabric 3 of the second cover sheet 46 can be selected to be lower than the density of the particles 7 on the first plastic ribbon fabric 3 of the first cover sheet 45, so that the second cover sheet 46 can be removed from the bag bottom 43 to open the bag 40.

[0064] Unit E shows the application of a third cover sheet 44 to the bag bottom 42 and the connection of the third cover sheet 44 to the second plastic ribbon fabric 14 or its weldable coating 15 of the bag body 41 according to the connection method according to the invention.

Claims

Claims:

1. A method for joining pieces of plastic ribbon fabric, comprising providing a first plastic ribbon fabric (3), the ribbons of which contain a first thermoplastic polymer, wherein discrete particles (7) containing a third thermoplastic polymer are fixed to a first surface (3a) of the first plastic ribbon fabric (3), providing a second plastic ribbon fabric (14), the ribbons of which contain a second thermoplastic polymer, wherein the second plastic ribbon fabric (14) is provided on one of its two opposite surfaces with a weldable coating (15) containing a fourth thermoplastic polymer, heating the discrete particles (7) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) above the softening temperature of the third and fourth thermoplastic polymers,bringing the discrete particles (7) of the first plastic ribbon fabric (3) into contact with the weldable coating (15) of the second plastic ribbon fabric (14), pressing the first and second plastic ribbon fabrics (3, 14) against each other, whereby the discrete particles (7) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) bond together, and optionally cooling the bonded pieces of the first and second plastic ribbon fabrics (3, 14).

2. Method according to claim 1, characterized in that the first plastic ribbon fabric (3) is provided on a second surface (3b) opposite the first surface (3a) with an optionally printed plastic coating (4) or a laminated plastic film.

3. Process according to claim 1 or 2, characterized in that the first and / or the second thermoplastic polymer is selected from PP, HDPE or PET.

4. Process according to one of the preceding claims, characterized in that the third and / or fourth thermoplastic polymer is selected from: PET, PP, PE, or a co- or terpolymer containing two or three of the following monomers: ethylene, propylene, vinyl acetate, alkyl acrylate, maleic anhydride, alpha-olefin.

5. Method according to one of the preceding claims, characterized in that the second plastic ribbon fabric (14) is provided on its surface opposite the weldable coating (15) with an optionally printed coating or a laminated plastic film.

6. Method according to one of the preceding claims, characterized in that the first and the second plastic ribbon fabric (3, 14) form longitudinal sections of a flat web-shaped substrate (16), wherein the flat web-shaped substrate (16) is shaped into a tube such that the discrete particles (7) of the first plastic ribbon fabric (3) are brought into contact with the weldable coating (15) of the second plastic ribbon fabric (14).

7. Method according to one of the preceding claims, characterized in that the particles (7) containing the third thermoplastic polymer have an average particle size of less than or equal to 1000 pm.

8. Method according to one of the preceding claims, characterized in that the particles (7) have a surface weight between 1 g and 20 g per m 2 , preferably between 3 g and 5 g per m 2 , are applied to the first plastic ribbon fabric (3).

9. Method according to one of the preceding claims, characterized in that the particles (7) are applied to the first plastic ribbon fabric (3) by: providing a release surface (6), providing and arranging a plurality of the discrete particles (7) on the release surface (6), wherein the release surface (6) has a temperature that is above a softening temperature of the third thermoplastic polymer, heating the particles (7) arranged on the release surface (6) above the softening temperature of the third thermoplastic polymer, bringing the first surface (3a) of the first plastic ribbon fabric (3) into contact with the release surface (6) and the softened particles (7) arranged thereon, so that the particles (7) adhere to the first surface (3a) of the first plastic ribbon fabric (3), then removing the first surface (3a) of the first plastic ribbon fabric (3) with the particles (7) adhering thereto from the release surface (6),and optionally cooling the particles (7) adhering to the first surface (3a) of the first plastic ribbon fabric (3) below the softening temperature of the third thermoplastic polymer.

10. A sack (40) with a sack body (41), wherein a bottom (42, 43) is formed at at least one end of the sack body (41) by folding the ends of the sack body (41), and the bottom is connected to at least one cover sheet (44, 45, 46), characterized in that the sack body (41) and the cover sheet (44, 45, 46) are connected to one another according to the method according to one of claims 1 to 9, wherein the cover sheet (44, 45, 46) forms the first plastic ribbon fabric (3) and the sack body (41) forms the second plastic ribbon fabric (14), or the cover sheet (44, 45, 46) forms the second plastic ribbon fabric (14) and the sack body (41) forms the first plastic ribbon fabric (3).

11. A sack (40) comprising a sack body (41), wherein a bottom (42) is formed at at least one end of the sack body (41) by folding the ends of the sack body (41), and the bottom is connected to a valve sheet (47), characterized in that the sack body (41) and the valve sheet (47) are connected to one another according to the method according to one of claims 1 to 9, wherein the valve sheet (47) forms the first plastic ribbon fabric (3) and the sack body (41) forms the second plastic ribbon fabric (14), or the valve sheet (47) forms the second plastic ribbon fabric (14) and the sack body (41) forms the first plastic ribbon fabric (3).

12. Sack (30) with a sack body (31) with or without side gussets (32) and with an open end, wherein the open end is closed by a sealing tape (33) and optionally sewn (34), characterized in that the sack body (31) and the sealing tape (33) are connected to one another according to the method according to one of claims 1 to 9, wherein the sealing tape (33) forms the first plastic tape fabric (3) and the sack body (31) forms the second plastic tape fabric (14), or wherein the sealing tape (33) forms the second plastic tape fabric (14) and the sack body (31) forms the first plastic tape fabric (3).

13. Device (20) for joining pieces of a first plastic ribbon fabric (3), the ribbons of which contain a first thermoplastic polymer, wherein discrete particles (7) containing a third thermoplastic polymer are fixed to a first surface (3a) of the first plastic ribbon fabric (3), and a second plastic ribbon fabric (14), the ribbons of which contain a second thermoplastic polymer, wherein the second plastic ribbon fabric (14) is provided on one of its two opposite surfaces with a weldable coating (15) containing a fourth thermoplastic polymer, characterized in that the device (20) comprises a first supply unit for supplying the first plastic ribbon fabric (3), a second supply unit for supplying the second plastic ribbon fabric (14), and a heating unit (23, 24, 25), wherein the first supply unit and the second supply unit are configured to supply the first plastic ribbon fabric (3) and the second plastic ribbon fabric (14) such that the first surface (3a) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) face each other, wherein the heating unit (23, 24, 25) is configured to heat the discrete particles (7) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) above the softening temperature of the third and fourth thermoplastic polymers,and wherein the first and second provision units are configured to bring the heated discrete particles (7) of the first plastic ribbon fabric (3) and the heated weldable coating (15) of the second plastic ribbon fabric (14) into contact with each other and to press the first and second plastic ribbon fabrics (3, 14) against each other so that the discrete particles (7) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) bond together.

14. Device (20) according to claim 13, characterized in that the first supply unit is designed as a roller (21) and the second supply unit is designed as a conveyor device (22), preferably as a conveyor belt or conveyor cylinder.

15. Device (20) according to claim 13 or 14, characterized in that the heating unit (23, 24, 25) comprises an air pump (23) for generating an air flow, a heating device (24) for heating the air flow, and an air nozzle (25) through which the heated air flow can be directed into a gap between the first plastic ribbon fabric (3) and the second plastic ribbon fabric (14).

16. Apparatus for producing box-valve bags (40), comprising a unit (A) for folding bottoms (42, 43) at the open ends of a tubular bag body (41); a unit (B) for inserting a valve sheet (47) into the bottom (42) and connecting the valve sheet (47) to the bag body (41); a unit (C) for applying a first cover sheet (45) to a first region of the bag bottom (43) and connecting the first cover sheet (45) to the bag body (41); optionally a unit (D) for applying a second cover sheet (46) to a second region of the bag bottom (43) and connecting the second cover sheet (46) to the bag body (41); optionally a unit (E) for applying a third cover sheet (44) to the bag bottom (42) and connecting the third cover sheet (44) to the bag body (41); and a conveyor device for conveying the bag bodies to said units (AE), characterized in that the unit (B) for inserting a valve sheet and / or the unit (C) for applying a first cover sheet and / or optionally the unit (D) for applying a second cover sheet and / or the unit (E) for applying a third cover sheet is / are equipped with a connecting device (20) according to one of claims 13 to 15.

17. A device for closing the open end of sacks (30), preferably equipped with side gussets (32), each having a tubular sack body (31), comprising a conveyor device (35) for conveying the sack bodies (31) lying flat in the transverse direction, a connecting unit (36) which is arranged on the conveyor device (35) in the region of the open ends of the sack bodies (31), wherein the connecting unit (36) has a device for feeding a sealing band (33) and is designed to arrange the sealing band in an egg-shaped or V-shaped manner enclosing the open end of each sack body (31), characterized in that the connecting unit (36) has at least one connecting device (20) according to one of claims 13 to 15 in order to connect the sealing band (33) to the sack body (31) by applying heat and pressure.

18. Set, comprehensive - pieces of a first plastic ribbon fabric (3), the ribbons of which contain a first thermoplastic polymer, wherein discrete particles (7) containing a third thermoplastic polymer are fixed on a first surface (3a) of the first plastic ribbon fabric (3); - pieces of a second plastic ribbon fabric (14), the ribbons of which contain a second thermoplastic polymer, the second plastic ribbon fabric (14) being provided on one of its two opposite surfaces with a weldable coating (15) containing a fourth thermoplastic polymer; and - a device (20) for connecting pieces of the first plastic ribbon fabric (3) to pieces of the second plastic ribbon fabric (14), characterized in that the device (20) has a first supply unit for supplying the first plastic ribbon fabric (3), a second supply unit for supplying the second plastic ribbon fabric (14) and a heating unit (23, 24, 25), wherein the first supply unit and the second supply unit are configured to supply the first plastic ribbon fabric (3) and the second plastic ribbon fabric (14) such that the first surface (3a) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) face each other, wherein the heating unit (23, 24,25) is configured to heat the discrete particles (7) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) above the softening temperature of the third and fourth thermoplastic polymers, and wherein the first and second provision units are configured to bring the heated discrete particles (7) of the first plastic ribbon fabric (3) and the heated weldable coating (15) of the second plastic ribbon fabric (14) into contact with one another and to press the first and second plastic ribbon fabrics (3, 14) against one another so that the discrete particles (7) of the first plastic ribbon fabric (3) and the weldable coating (15) of the second plastic ribbon fabric (14) bond to one another.

19. Set according to claim 18, characterized in that the first supply unit is designed as a roller (21) and the second supply unit is designed as a conveyor device (22), preferably as a conveyor belt or conveyor cylinder.

20. Set according to claim 18 or 19, characterized in that the heating unit (23, 24, 25) comprises an air pump (23) for generating an air flow, a heating device (24) for heating the air flow, and an air nozzle (25) through which the heated air flow can be directed into a gap between the first plastic ribbon fabric (3) and the second plastic ribbon fabric (14).

21. Set according to one of claims 18 to 20, wherein the pieces of the first plastic ribbon fabric (3) form cover sheets (44, 45, 46) and the pieces of the second plastic ribbon fabric (14) form tubular bag bodies (41), or wherein the Pieces of the second plastic ribbon fabric (14) form the cover sheets (44, 45, 46) and the pieces of the first plastic ribbon fabric (3) form the tubular bag bodies (41), further comprising a unit (A) for folding bottoms (42, 43) at the open ends of the tubular bag body (41); a unit (B) for inserting a valve sheet (47) into the bottom (42) and connecting the valve sheet (47) to the bag body (41); a unit (C) for applying a first cover sheet (45) to a first region of the bag bottom (43) and connecting the first cover sheet (45) to the bag body (41); optionally, a unit (D) for applying a second cover sheet (46) to a second region of the bag bottom (43) and connecting the second cover sheet (46) to the bag body (41); optionally, a unit (E) for applying a third cover sheet (44) to the bag bottom (42) and connecting the third cover sheet (44) to the bag body (41); and a conveyor device for conveying the bag bodies to said units (AE), wherein the unit (B) for inserting a valve sheet and / or the unit (C) for applying a first cover sheet and / or optionally the unit (D) for applying a second cover sheet and / or the unit (E) for applying a third cover sheet is / are equipped with the connecting device (20).

22. Set according to claim 21, wherein the first plastic ribbon fabric (3) forms the valve leaf (47) when the second plastic ribbon fabric (14) forms the bag body (41), or wherein the second plastic ribbon fabric (14) forms the valve leaf (47) when the first plastic ribbon fabric (3) forms the bag body (41) 23. Set according to one of claims 18 to 20, wherein the pieces of the first plastic ribbon fabric (3) form sealing strips (33) and the pieces of the second plastic ribbon fabric (14) form tubular bag bodies (31) equipped with or without side folds (32), or wherein the pieces of the second plastic ribbon fabric (14) form the sealing strips (33) and the pieces of the first plastic ribbon fabric (3) form the tubular bag bodies (31), further comprising: a conveyor device (35) for conveying the bag bodies (31) lying flat in the transverse direction, a connecting unit (36) which is arranged on the conveyor device (35) in the region of the open ends of the bag bodies (31), wherein the connecting unit (36) comprises a device for Feeding of the sealing tape (33) and being designed to arrange the sealing tape (33) in a U-shape or V-shape enclosing the open end of each bag body (31), wherein the connecting unit (36) has the connecting device (20) for connecting the sealing tape (33) to the bag body (31) by applying heat and pressure.

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