EP0264950A2 - Thermoplastic bag and method and apparatus for the continuous production of this bag from a tubular sheet material - Google Patents

Abstract

In the method, a tear-resistant closure tape (7) is continuously connected with adhesive force, to at least one side of a tubular web in the longitudinal extension along a side edge of the tubular web intended for forming the bag opening. At least one side of the tubular web, extending on the inside parallel and immediately next to the closure tape, applied with adhesive force, is constructed with a perforation line (8). Then the tubular web is welded repeatedly transversely and/or continuously longitudinally and, optionally, the welds are separated or the web is cut off next to the welds, by which means bags (10) are obtained which have a side weld and/or bottom weld, are fitted with a tear-off closure tape along the bag opening (12) and the bags can be stacked, if appropriate being folded into packs of bags, and packaged to form display packagings. <IMAGE>

Description

The invention relates to a sack made of thermoplastic film, the front and back of which are formed from a flat tubular film. The invention further relates to a method and devices for producing sacks, in particular garbage sacks made of thermoplastic film tubes, the extruded blown film tubes being flattened to form tubular webs, possibly cut open in the longitudinal extension of the tubular web by at least one longitudinal cut, then the tubular web in cross-section and / or continuously welded lengthways and optionally the weld seams are separated or cut off next to the weld seams, whereby bags with side seams and / or bottom seams are obtained. After being folded, the sacks can be stacked in sack packs and packed into display packs.

Plants for the continuous production of pack sacks made of thermoplastic are known in a wide variety of designs, for example to those in DE-PS 24 57 039, DE-PS 62 36 321, DE-PS 21 04 082, DE-PS 34 21 680, DE -AS 27 55 860 and 27 43 494 and DE-OS 28 10 204 as well DE-PS 26 30 341 devices described.

In all these sacks or bags made of plastic films that can be produced with the known methods and devices, it is perceived as disadvantageous in use that they do not have any closure means belonging to the bag for closing after filling, but must first be obtained. Furthermore, in particular in the case of large-format pack sacks, the task arises of packaging them in a small format that is as manageable as possible in display packaging, which can accordingly be offered for retail sale. It is known to reduce the size of the individual sacks by folding them and then to stack them on top of one another in the desired numbers as sack packs to form display packs. In this case, an orderly individual removal of the folded sacks from the display packs is no longer possible after prolonged use, since the folded sacks slip in the display packaging or the individual removal is impeded by undesired entrainment of additional sacks. Sack chains in a rolled-up form with perforated dividing lines or sack chains folded in accordion fashion are also known for bulk buyers.

A bag is already known from DE-OS 22 49 584, in which the edge is perforated along the open end during manufacture, so that a tear-off tensile strip is formed from the bag material. However, this tearable tensile strip does not have sufficient tear strength in the case of thin pouch films, which ensure that the filled pouch is properly tied.

The invention has for its object to improve pack sacks made of plastic films l for handling when they are used, in particular to provide a suitable closure means, which enables the filled sack to be closed effortlessly at any place and at any time, and to provide an economical, environmentally friendly manufacturing process. Furthermore there is the task to assemble large-format sacks, such as garbage sacks, in handy display packs, which, in the case of small formats, obtained by folding the parts, nevertheless allow the individual sacks to be removed individually and prevent the sacks remaining in the display packaging from slipping.

This object is achieved according to the invention in a sack made of plastic film in that a tear-resistant closure tape parallel to the upper edge of the sack opening and extending across the width of the sack is firmly connected to at least one of the sides of the sack and in the area between the upper edge of the sack opening and the a perforated line is formed parallel to the closure band with the closure band connected to the sack, along which the closure band can be torn off.

The fastening tape required for closing or tying a filled sack or bag is thus fastened to the sack and is torn off the sack along the perforation line at the required time. It is now irrelevant at which location and at what time the sack is to be closed, the fastening tape required for binding is always within reach and of sufficient length. According to the innovation, a fastening tape is not only a tape, but also a cord, thread or the like.

For sacks or bags which have a flap projecting on one side of the sack opening over the width of the sack in the extension of one side of the sack, according to a further proposal of the invention, the fastening tape is connected to the flap in a manner that runs parallel to the upper edge of the sack opening and in the area between the perforated line parallel to the upper edge of the bag opening along the top edge of the bag opening and the fastening tape fixed to the flap, along which the fastening tape can be torn off. To tie the sack is then at the appropriate time with the flap torn fastener tape available.

The invention allows various possibilities of attaching the fastener tape to the projecting flap of the sack. It is particularly preferred to fasten the fastener tape by welding it into an envelope formed by folding the flap over. However, it is also possible to weld the fastener tape directly onto the flap. Adhesive connections can also be used as adhesive connections for the closure tape with the sack or the flap. For example, tapes coated with hot-melt adhesive can be connected to the plastic film of the sack or flap using pressure and heat. The flap with closure tape to be torn off along the perforation line is then used to close the sack. It is also conceivable to strip the flap from the fastener tape, i.e. to release the fastener tape from the envelope if the connection allows.

According to a further variant, the closure tape is inserted and welded between the two sides of the sack along the upper edge thereof and the perforation is provided in both sides of the sack and the sack opening is formed along the perforation.

Such an attachment of the sealing tape, preferably by welding, is particularly advantageous for very thin plastic films used for the production of the bags, in particular less than 20 μm thick.

An advantageous method for producing the bags with a tear-off sealing tape suggests that before the production of the weld seams a tear-resistant sealing tape which can be welded continuously to the plastic film of the bag in the longitudinal direction along a side edge of the tubular web intended for forming the bag opening with at least one tubular web side is particularly adherent Welding, is connected and at least one side of the tube sheet with a perforation line is formed parallel to the inner side of the sealing tape, along which the sealing tape can be torn off the tube sheet.

According to the invention, a closure tape is not only to be understood as a tape or ribbon, but also a cord, thread or the like, which is suitable for binding.

The preferred connection of the fastener tape to the tubular web is produced by welding, the fastener tape consisting of a suitable plastic that can be welded to the tubular web and is either welded onto the tubular web or preferably welded in, namely over the entire surface.

In a preferred advantageous embodiment of the invention, the procedure is as described in claim 6. Here bags are produced which have a flap projecting on one side of the sack opening across the width of the sack in the extension of one side of the sack, with which the fastening tape is connected to the flap so that it runs parallel to the upper edge of the sack opening, in particular welded and in the area between the flap Top edge of the bag opening and the fastening tape fastened to the flap, the perforated line is formed parallel to the upper edge of the bag opening and the fastening tape, along which the fastening tape can then be torn off.

According to the invention, the fastening tape can be attached in different ways to the projecting flap of the sack or the tube sheet. In a preferred advantageous embodiment, the fastener tape is continuously applied to the flap and hemmed in by flipping over the flap edge and continuously welded to the flap over the entire surface.

A further possibility of producing sacks with a tear-off closure band is proposed according to the invention in accordance with the features of claim 9. This procedure is particularly advantageous for tubular webs, the width of which corresponds to a bag length - or for which, in the case of a tubular web width corresponding to two bag lengths, a separating weld seam forming a bag bottom weld seam is made in the center in the longitudinal direction in addition to side weld seams - and in which the closed side edges of the flat tubular web are not cut open. Instead of such a longitudinal cut, only the longitudinal perforation at the desired distance from the edge - corresponding to the sealing tape width to be welded - is carried out continuously through both sides of the tubular web and the flap or envelope into which the sealing tape is to be inserted and connected is only opened at the time of the Opening of the fastener tape opened. According to this very advantageous proposal of the invention, the previous cutting and possible slipping of the tube web sides as well as the opening and later folding over of the edge strip of the tube web are saved. After tearing open a perforation, in particular the overhead hose web side, the later sack opening is formed at the same time and the perforation line in the lower hose web side remains for tearing off the fastener tape, which is caused by the tearing of a perforation line formed envelope of the lower side of the tube sheet can be inserted.

However, it is also possible to insert and weld the sealing tape along a cut side edge of the tubular web between the two tubular web sides and to weld the perforated line next to the welded-in sealing tape internally, i.e. on the tubular track side, to be formed continuously through both tubular track sides. This procedure for attaching the fastener tape is particularly advantageous for very thin plastic films used for the manufacture of the pack sacks, in particular less than 20 μm thick. It is also possible to weld the sealing tape onto one side of the superimposed tubular web sides, the sealing tape welding to the adjacent tubular web side and the two tubular web sides. The continuous perforation makes it possible to create the later bag opening by tearing off the fastener tape along the perforated line.

For the invention, a fastener tape made of ribbons made in particular of stretched polyolefins such as HDPE or polypropylene is preferably used. The sealing tape is applied continuously and extends over the entire sack width in the finished sack, and is flush on both sides with the sack width, ie the side edges or seams. The fastener tape can advantageously have a width of approximately 3 mm to 6 mm and a thickness of approximately 10 to 50 μm. Other dimensions are also possible. The height of the flap of the tubular web protruding during production, which is caused by the offset of the longitudinal cuts, should be approximately 10 to 40 mm. The flap is preferably turned over by almost half of its protrusion for welding in the fastener tape.

The invention can be used with particular advantage for the production of garbage bags, garment bags, etc. for the household, which have formats of about 500 to 900 mm in width and about 700 to 1200 mm in length; however, smaller bag formats can also be produced using the method according to the invention.

The bag shapes suitable for the invention can be different, but preference is given to packing bags without side gussets, but with side weld seams or side parting seam seams and with or without bottom fold. Such pack sacks have the highest possible level of safety thanks to folded edges instead of a weld seam on the bottom of the sack. With appropriate film tube routing and the production of appropriate weld seams, however, pack sacks with bottom weld seam and with or without side gussets can also be equipped with a tear-off closure tape in the area of the subsequent bag opening.

Monoplastic or mixed films made of polyolefins, such as LDPE, HDPE, and / or LLDPE or e.g. Co-extruded multilayer films from such or other suitable thermoplastic plastics in question. Thermoplastic materials that can be welded particularly well can be used with advantage. Depending on the field of application and plastic, the film thicknesses are selected from 10 µm to approximately 50 µm.

The sacks produced according to the invention with welded-on and welded-on and tear-off sealing straps directly at the sack opening are to be transferred for the individual use by the end user in suitable handy display packaging in suitable quantities, for example 6 to 30 sacks per packaging, in the continuous production of the sacks . In addition to the economical production method, it is also a concern of the invention to design the display packaging for the end user in such a way that simple and safe removal of individual bags from the display packaging is made possible, in particular also in the case of large-format bags which do not Clutter in the packaging that is not yet needed.

To solve this problem, it is proposed in a further development of the method for producing bags with welded-on sealing tapes that the bags equipped with the sealing tape, if necessary after single or double U-folding of the individual bags in their longitudinal extent with a closed side or Fold edge in the transport direction at the front, are stacked one above the other in a predetermined number to form a flat bag pack and the bag pack is folded into a stack in a W-like shape, with either the outer folding leg of the W stack, on the edge of which the closure straps of the bags run, longer than the other, in particular, the same long folding leg is formed and forms an edge strip projecting on one side over the W stack and the W stack is introduced into a display packaging or one of the folds of the W stack is formed by two folding legs which are longer than the other folding legs and thus forms the above plucked hem.

The process according to the invention enables large-format sacks to be continuously folded not only into small formats, but also to create a pack of a plurality of sacks in a pack or stack, which enables simple and safe removal of an individual sack from the display packaging. This simple, safe removal is done by accessing the protrusion the edge strip of the sack inside the W fold of the stack. The sacks that are not required remain in the orderly position in the W-shape in the display packaging and are not disturbed by the removal of the sack inside the W-fold. The bags made of plastic films can be easily converted into the folded shape of the W stack due to their suppleness, although it is surprising that the bags can be removed safely and in an orderly manner, since they tend to stick together due to electrostatic charging and also have no inherent strength and thus also tend to slip strongly.

According to the method according to the invention, the individual flat sacks can be folded continuously at least once in order to reduce at least one of their dimensions, namely length or width, and are then collected in this folded flat form on top of one another to form sacks of a predetermined number of sacks. The individual sacks can be folded together, for example, to half a sack width or length or by double folding to a third sack width or length or to a quarter sack width or length. In this way it becomes possible, for example with a sack width of 800 mm, to reduce this to 200 mm with a double fold and with a length of 1000 mm by a W-fold with 6 legs, which takes place transversely to the previous individual fold, this to 200 mm To shorten. The display packaging then has a dimension that only insignificantly exceeds the format of the W stack of approximately 200 × 200 mm, the height or thickness of the packaging being based on the number of bags unfolded in the stack and, for example, 10 packed bags aforementioned size is in the millimeter range.

When the bags are folded individually, it can be advantageous to prevent side seams from sticking together during manufacture, to fold the side edges with weld seams to a small offset of the edges. Here, the fold line is offset from the center line of the bag approximately according to a width of the weld seam of the weld seams running parallel to the fold line. This enables the bags to be laid correctly and W stacks to be formed for the subsequent display packaging and prevents welding.

For the formation of the W stack, an even number of folding legs is preferably formed, in particular 6 folding legs. The number of folding legs depends on the length of the sacks to be unfolded and the desired format. The number of bags contained in a W stack also plays a role. For household packs, i.e. Small packs for the individual removal of bags, as required, are usually provided in a stack of about 5 to 30 bags.

The stack is preferably folded with the folding height of the folding legs remaining the same except for one protruding folding leg. The overhang of the edge strip of the protruding folding leg should be approximately 15 to 30 mm in order to ensure that the sack can be gripped and gripped correctly for individual removal.

Bags or boxes or folding boxes made of plastic films or paper or cardboard or the like can be provided as display packaging, into which the W stacks of bags are filled. The display packaging can be sealed with a flap, which is either designed with a tear-off perforation for the production of the removal opening or with a flap, which is provided as an envelope with a self-adhesive layer, or can be simply welded closed or with a tear-off tape that creates a removal slot when torn off. The display packaging can also have a hanging tab to make it easily accessible to place hanging strips.

The W-shaped unfolding of the sacks into a stack has the further advantage that the sack areas with the welded-in sealing tapes, which represent a material accumulation compared to the other sack parts, are laid in the protruding edge strips of the W stack and thus space compensation in the display packaging , ie a uniform use of space is made possible and the bulging over the remaining flat sack parts is avoided.

In order to carry out the method according to the invention for producing pack sacks, in particular garbage bags made of plastic films with a weldable tear-off sealing tape, conventional systems contain an extruder with a film blow head for producing the tubular film from thermoplastic plastic, a lay-flat device for the tubular film to the tubular web, and possibly a longitudinal cutting device for the tubular web, a storage device for the tubular web, a film removal device for the tubular web stored in the storage, a welding device for producing welds or separating welds in the transverse and / or longitudinal direction of the tubular web for producing bags with side seams and / or bottom seams, and possibly folding devices for the longitudinal folding of the individual sacks, a sack depositing device and packaging device as well as means of transport connecting the individual stations. Such systems are known and can optionally also be equipped with a printing machine for single-sided or double-sided single-color or multi-color printing of the tubular web, which is preferably arranged to act on the tubular web after the film removal device and before the welding of the separating seams. Also devices for insertion Bottom folds can be provided in a known manner at a suitable point in the production process.

For the production of bags with tear-off sealing tapes, a generic system according to the invention is equipped with a feeding device and connecting device for the sealing tape arranged between the film take-off device and the downstream welding device, and a perforation device according to the features of claim 11. The system designed according to the invention enables the continuous production of sacks with a tear-off closure band, which extends over the sack width and is formed next to the sack opening.

In order to prevent the fastener tape from running and to apply this as precisely as possible in the desired position on the tubular web side along the edge, it is proposed in a further development of the device according to the invention that the feed device has a feed funnel for the fastener tape and a fold-over guide plate for turning over the underlying tubular web side edge over the placed one Has closure tape. This achieves the formation of a straight fastener tape with a uniform connection area. To establish the connection, in particular a welded connection, a welding device, in particular a rotating welding device acting in the longitudinal direction, for example a welding wheel for welding the sealing tape to the adjacent tube web sides, is provided immediately after the folding device. Immediately following the rotating welding device, the perforation device for forming the linear perforation extending in the longitudinal direction is provided directly next to the weld seam for the fastener tape. This perforation line can be produced, for example, with a perforation wheel.

An advantageous embodiment of a system according to the invention for carrying out the method according to claim 10 can be gathered from the characterizing features of claim 12.

The tear-open device for a tubular web side along the one perforation line is preferably integral with a feed, e.g. a feed finger for the fastener tape is formed. The distance of the perforation line from the folded edge of the flat tube results in the width of the flap or the envelope into which the closure tape is preferably inserted. A perforation device downstream of the welding device is not required.

After the fastening tape has been applied and the tear-off perforation has been produced, the tube web thus prepared is assembled by means of welding or separating welding devices known per se in the desired dimensions by means of transverse weld seams or transverse and longitudinal weld seams. The sacks with sealing tapes thus produced are then continuously collected into sack packs and, depending on the area of application, folded into smaller formats and packaged into display packs for the household or the like. To achieve a particularly advantageous small-format display packaging of several bags in one package, which at the same time allows a simple and orderly individual removal of the bags, the generic system for producing pack bags is equipped according to the invention with a W-folding device according to the features of claim 13, which folds the whole Bag packing and orderly insertion and packing in display packaging enables.

Further advantageous individual features of the method according to the invention and the system for carrying out the method and for producing pack sacks, in particular garbage bags, with welded-in tear-off sealing tape and possibly display packaging with stacks of pack sacks folded in a W shape are explained by way of example with reference to the drawing.

• Figur 1, 3, 5 eine schematische Darstellung einer Anlage zum Herstellen von Säcken
• Figur 2, 4, 6 eine schematische Darstellung der Sackent­stehung mit einer Anlage gemäß den Figuren 1, 3, 5
• Figur 7 und 8 zwei Ansichten zur Erläuterung des Schnitt­vorganges gemäß Figur 2d
• Figur 9 und 10 zusätzliche Teilansichten zu der Verschluß­bandaufbringung gemäß Figur 4 h1 und h2
• Figur 11 schematische Darstellung einer Faltenein­legevorrichtung
• Figur 12 eine schematische Darstellung für eine W -Falteinrichtung
• Figur 13 eine schematische Darstellung eines Greifers für den W -Stapel
• Figur 14 eine Teilansicht eines Müllsackes
• Figur 15 Teilansicht einer Verschlußbandeinlegung
• Figur 16 und 17 Ansichten verschiedener Säcke
• Figur 18 bis 21 Ansichten verschiedener Varianten gefalteter W-Stapel von Säcken
• Figur 22 Ansicht einer Displayverpackung

Show it

• Figure 1, 3, 5 is a schematic representation of a plant for the production of bags
• Figure 2, 4, 6 is a schematic representation of the sack formation with a system according to Figures 1, 3, 5
• 7 and 8 show two views to explain the cutting process according to FIG. 2d
• Figures 9 and 10 additional partial views of the fastener tape application according to Figure 4 h1 and h2
• Figure 11 is a schematic representation of a fold insertion device
• Figure 12 is a schematic representation of a W-folding device
• Figure 13 is a schematic representation of a gripper for the W stack
• Figure 14 is a partial view of a garbage bag
• Figure 15 partial view of a fastener tape insert
• Figures 16 and 17 views of different sacks
• Figure 18 to 21 views of different variants of folded W-stack of bags
• Figure 22 View of a display packaging

Continuous sack production begins according to FIG. 1 with the extrusion of a tube according to FIG. 2a by means of the extruder I, which is inflated with the film blowing head II to form the film tube 1 according to FIG. 2b. Here, monofilms can be produced from only one thermoplastic, such as LDPE, HDPE, LLDPE, or mixed foils from blends of the aforementioned plastics, or multi-layer tubular foils, so-called coextrusion foils, as a combination of the aforementioned plastics or other suitable thermoplastic plastics. The film tube is subsequently laid flat to form the web 1 according to FIG. 2c by means of flat laying devices III known per se. For the dimensions, ie the diameter of the film tube 1, it should be noted that the film diameter should correspond to the simple, preferably twice the bag length. Then it is possible to manufacture the desired bags continuously by means of cross-seam separating welds at intervals of the desired bag width. With a desired garbage bag format of, for example, 700 mm wide and 1100 mm long, the width of the tubular web according to FIG. 2c is 1100 mm or double 2200 mm. In the case of twice the width of the tubular web in relation to the length of the sack, the tubular web is to be divided into two half-tubes 1a, 1b according to FIG. 2d before winding or folding for storage by means of a longitudinal cut and then each half-tube is wound up on a roll 4 or placed in a container 5. The winding-up Va or storage devices Vb are then to be provided twice in each case.

If the sacks are to be equipped with a sealing tape protruding along an edge on one side of the sack, the longitudinal cutting device IV is for dividing the tubular web into two half-tubes with offset separating knives for producing separating cuts in the upper and lower sides of the tubular web which are offset in parallel by the offset a 2 as can be seen from FIGS. 2d, 7 and 8. The mutually offset longitudinal cuts 2 produce an edge strip projecting on one side along a side edge in the running direction or transport direction of the half-tubes, also referred to as a flap 11. For continuous further processing, it is advantageous if the subsequent storage of the half-tubes takes place in such a way that the flap side of the half-tube on the same side, e.g. the left side in the running direction, and the projecting flap side is arranged below. The offset a of the separating cuts 2 from the center line 3 should be approximately 10 to 40 mm. The longitudinal folding edge 15 of the tubular web or half tube forms e.g. the bottom edge of the bottom of the sacks to be made from them.

In the event that a narrow film tube is blown, the flattened web width of which corresponds to only one garbage bag length, the separating cut in the longitudinal extension would preferably be offset by half the desired flap width next to the side edge, so that a protruding flap along one side edge of the cut-open tube web for that later adhesive connection is created with the fastener tape. The half-tubes are then either wound, as shown in FIG. 2e _a , on 2 identical roll winder 4, which are, however, arranged in mirror image to one another, or are placed in a Z-fold in containers 5, as shown in FIG. 2e _b . In all cases, care must be taken to ensure that the side of the tubular web, which has the projecting flap 11 along the side edge, is closed at the bottom in the film running direction comes lying down. The film is then removed from the memory by means of known film removal devices VI in the reverse direction, as shown in FIGS. 2e _a , e _b with dashed arrows. The film take-off device VI can be equipped with a roll take-off unit for a continuous take-off of the tubular webs, a dancer roll unit for controlling the continuous take-off speed and a web guiding system for straight web entry into the subsequent stations. The system stations I to VI, as described above, are known in detail, as can also be seen, for example, from the publications cited at the beginning.

If the sacks to be produced are to be printed, a printing press, for example a flexographic printing press of known design for single-sided or double-sided single-color or multi-color printing, as printing station VII, as shown in FIG. 3, can be arranged directly after the take-off station for the tubular webs. With or without printing 6, the tube webs 1, 1 a drawn off from the unwinding station VI according to FIG. 3 and FIG. 4 f 1 and f 2 are fed to the stations VIII to X for feeding and connecting the fastener tape and producing the tear-off perforation. For example, rolls with the fastener tape 7 on one Drainage point provided and pulled from here and placed on a flap on the flap 11 and flap 11 folded along a folding sheet guide over the closure tape 7 and immediately afterwards with the flap - top and bottom - firmly connected, in particular welded, as shown schematically in Figure 4h₁ shown. For an orderly feeding of the closure tape 7 the feed hopper and the folding sheet guide should be arranged close to each other in order to bring the fastener tape as close as possible along the edge of the cover. In order to avoid a course of the closure band and the flap envelope, the flap is welded to the closure band immediately after the flap, preferably using a rotary welding process in which the flap envelope is mechanically compressed at the same time, for example by means of a welding wheel that works in the direction of film travel. When the tubular web is at a standstill, the welding wheel lifts automatically, so that the tubular web does not burn out. A corresponding control can be provided. Furthermore, a second fastener tape drainage point with a supply roll can be provided, on which the subsequent roll is placed and the beginning of the fastener tape is connected to the end of the rolls that are still in the unwinding process, welded together in order to ensure continuous production or shutdown of the system when the roll of the machine runs out Furthermore, a control system can be provided for the feeding of the fastener tape, which automatically shuts down the system in the event of a tear or when the roll runs out without a subsequent roll.
Immediately after the welding device IX for the fastening tape 7 and the flap flap, the production of the longitudinal perforation 8 follows by means of a perforation device X, for example a perforation wheel. The system of producing a longitudinal separation perforation, for example by means of a perforation wheel on a rotating ring of a ball or roller bearing, is known per se.

When equipping a half-tube with a sealing tape along the open side edge 12 of the half-tube 1a, as shown in FIG. 4h 1, care must be taken that the perforation in the longitudinal direction takes place immediately after the welding, in order to position the tear-off perforation line 8 exactly on the lower side of the hose where the sealing tape is attached Envelope 11 should be slightly less than half of the flap width overall, so that between the open edge 12 of the half-tube in the longitudinal extension and the welded-in sealing tape 7 there remains a narrow strip of the lower side of the tubular web for the attachment of the perforation 8.

FIG. 9 shows the closure band welded into the flap envelope 11 again in detail, the weld 9 connects the closure band flat with the adjacent flap sides.

It is also possible to equip sacks with a closure band 7, which extends over the entire sack width, in which no flap protrudes in the region of the sack opening, in which the tubular web 1 is cut along a side edge 12, as can be seen in FIG. 4f 2. In this variant, the fastener tape 7, as shown in Figure 4h₂ and 10, inserted between the bottom and top of the tube sheet in the area of the open edge 12, for example by means of a feed funnel and firmly connected by means of a rotating longitudinal welding device in particular and then the longitudinal perforation 8 in parallel directly in addition to the weld seam for the sweatband on the side facing the tube sheet.

FIG. 15 shows the introduction of the fastener tape 7, which has been pulled off from an unwinding device (not shown in any more detail), into a flap envelope 11, which is only produced at the time of introduction. The flattened tube sheet 1 is not cut open immediately, but is first provided with a perforation 2a extending through both tube sheet sides along a distance from the closed folded edge corresponding to the desired width of the flap envelope 11. When the fastener tape 7 is fed between the two hose web sides, the upper hose web side is simultaneously separated by the feed device (VIIIa) along the one perforation line 2a, so that the cutting edge 2 and the flap 11 folded over are formed. The closure inserted into the flap 11 already folded over band 7 is then welded in. The perforation line 8 in the lower hose web side then enables the closure tape with flap flap to be torn off later along the opening formed by cutting open the perforation line 2a in the upper hose web side, ie later bag opening.

Subsequently, the tubular webs 1a, 1 equipped with the sealing tape 7 along a side edge are fed to a seam welding machine which, depending on the design of the tubular webs, produces cross-weld seams or separating weld seams and, if appropriate, longitudinal weld seams, at the desired bag dimensions at appropriate intervals. If half-tubes 1a, as shown in FIG. 4h₁, which have a folding edge which later forms the bottom of the bag on the side opposite the closure band, are produced in the subsequent welding station XI by cross-welding separating weld seams which form the later side edges 13 of the simultaneously assembled bags Form 10 according to Figure 4j. The same can be done, for example, with a tubular track according to FIG. 4h₂.

Such seam welding machines, as they can be used in the welding station XI, are known and include, for example, a roll take-off unit for a continuous web take-off, a roll vibrator for controlling the continuous take-off speed, a drive unit, a print repeat control with a photo cell probe, a deflecting roll unit and a hot wedge separating welding device with a pair of terminal strips. With the separation welding device, the sealing tape is also cut through flush with the bag width.

16 and 17 show sacks in the embodiment according to the invention.

Figures 16 and 17 each show a sack 10 made of thermoplastic film, e.g. a monofilm made of LDPE. The front 1a and the back 1b of the sack are formed by a flat film tube or half tube, the folded edge of which forms the sack bottom 15, the side edges are closed by weld seams or separating weld seams 13. At the sack opening 12, the film web on the back 1b in the form of the flap 11 extends on one side over the entire sack width. The flap is preferably folded to less than half of its protruding length in the direction of the bag opening, with the closure tape 7 inserted into the flap envelope 11a and through the flap envelope running parallel to the bag opening with the flap underside and with the fastening tape 7 connecting weld 9, is welded. The perforated dividing line 8 is formed between the flap envelope or the weld seam area 9 and the bag opening 12, so that the sealing tape, which is preferably welded directly at or next to the bag opening, can be torn off along the perforation 8 if necessary. The fastener tape 7 preferably closes flush with the bag width, i.e. the flap width.

In the case of the sack 10 according to FIG. 17, the sealing tape 7 made of polyethylene is inserted parallel to the upper edge of the front and rear sides 1a, 1b between the sides 1a, 1b and is adhesively connected to the adjacent areas of the sack sides 1a, 1b, e.g. through the weld 9.

At the same time, the perforation 8, which passes through both sides of the bag 1a, 1b, is provided at a distance from the upper edge such that the entire welded-in closure tape 7 with welded area 9 can be separated along the line of perforations and thus the bag 10 is opened at the same time. The perforation line also marks the sack opening.

If the sack 10 is to be used according to FIG. 17, the band 7 is torn off along the perforation 8 and, after the sack has been filled, the sack opening can be tied with the torn band 7.

The individual sacks 10 produced in this way are now continuously assembled and packaged, as shown in the continued system parts according to FIGS. 5 and 6 and an exemplary embodiment. In the case of large bags, for example household garbage bags, the format is reduced in a known manner by folding, for which purpose transverse folding stations XII and XIII are provided.

A possible double folding device XII, XIII for a single longitudinal bag folding is shown schematically by way of example in FIG. 11. The first folding of the bag 10 in a U-shape according to FIG. 6k takes place with the bag 10 resting flat on a transport device, according to FIG. 11, immediately after the bag has left the separating weld device XI. And the terminal strips of the welding device open. In order to adjust the folding slot position on the longitudinal center line of the sack, the entire folding station XII and XIII is adapted to be displaceable to match the different sack widths at a corresponding distance from the welding station XI. For example, the adjustment range for bag widths between 450 and 900 mm is 225 to 450 mm. Due to the stationary design of the entire folding device, it is achieved that in the first folding for the sack no conveyor belts are required, which have to transport the full sack width during one work cycle, for example at 700 mm width and 90 cycles per minute, so that the barrel - And the transport speed of the conveyor belts required for the subsequent side folding for the double-folded sack can already be adapted to half the sack width.

When setting the first fold to the folded position, see arrow A for the air nozzle folding wedge, a slight offset, approx. 5 to 10 mm away from the actual sack center line, must be taken into account in order to ensure a corresponding offset of the side weld seams 13 along the side edges of the sack 10 when To achieve folding. The rear, ie the last welded side seam should protrude beyond the front weld seam in order to prevent the hot weld seams from sticking together during continuous production, see also FIG. 6k. The subsequent second folding is carried out while the sack is not moving, the function of the air nozzle folding wedge B being controlled for the second folding, for example by means of a photocell or light barrier for registering the incoming sack 10 1. The bag is then folded again in a U-shape to the width of the bag quarter as it passes through the second folding section, as shown in FIG. 6L. After passing through the second folding station XIII, the double-folded sack 10₂ with its total of 8 layers compressed as a result of the passage through the conveyor belt unit 21 reaches a width of approximately 175 to 180 mm with an extensive sack width of 700 mm on the storage rake or storage rack 30 and is stacked into the flat sack pack 20, see FIG. 6 m. As a result of the closed folding edge 14 of the sacks emerging from the conveyor belt unit 21 at the front after the two folding processes, no air can penetrate between the open folding edges lying one above the other and this provides an overall guarantee for a safe and clean sack storage and sack stacking. Such bag stacking devices XIV with clipboard rake are known and enable continuous bag stacking without an interruption in the empty cycle. The temporarily stored sack packs, for example a bag of ten (containing 10 individually folded sacks) are then taken over by a gripper transport unit and transported to the subsequent W folding device XV. The task of the W folding device is to fold the sacks of bags across to those already made Fold single folds or across the length of the bag to a smaller format. It is important here that the bags are not folded individually, but that the bags are folded together. A schematic representation of the W folding device is additionally shown in FIG. The W folding device contains a storage rack, on which the bag pack 20 taken over by the double folding device is placed, a vertical folding unit with at least two, preferably three movable, for example pneumatically actuated folding wedges 21, a deflection and guide finger unit with at least three, preferably four movable, for example pneumatically controlled guide fingers 22 and a smoothing device with two smoothing brushes for venting the folded bags.

The storage rack, not shown, assigned to the W folding device is centered with the arrangement of the folding wedges and guide fingers. After the placement of the bag pack 20, the fingers 22, which are in the rest position during the placement process, are pushed forward similarly to the function of a clipboard calculation above the bag pack and at the same time lowered onto the bag packs in order to clamp them slightly. In the storage rack in this position, rotating rollers, for example, are arranged as a counter support. At the same time, a gripper (not shown in detail above the folding area) descends from above and sits on the vertical fold arranged in the middle position in order to clamp the sack pack so that it cannot slip during the subsequent W folding. Smoothing brushes can now be lowered to the right and left of the gripper on the sack packs in order to smooth them while they are being drawn into the folding device and to remove the air from the sacks. The middle folding wedge 21 is pushed vertically upwards and thus executes the first folding process, the gripper, which clamps the sack packs, goes up with it. Subsequently, the folding wedges are pushed up on the left and right at the same time and thus perform the second and third folding, for example with the same folding height leads to a 1/6 product length pack in a W fold, ie with a bag length from 1100 mm to approx. 183 mm. The stroke of the folding wedges is also adjusted according to this length.

Figure 12 shows schematically the position of the W-folding device after folding. The direction of movement of the folding wedges 21 is shown by the arrows. In order to obtain a protruding edge strip for the W-shaped folded stack 200 for easy removal of the sacks, the fold lines calculated in the middle of the sack are defined such that a protruding edge strip of approx. 15 to 20 mm in the area of the sack opening remains, which serves as a starting line for the plucking of the individual sack. This protruding edge strip of the bag pack, designated by 201, also includes the sealing tapes welded in along the bag openings.

Since the W fold, as described above, originates from this slightly offset center of the fold line and the fold wedges 21, center as well as left and right, are set to the same butt height, this system always ensures a constant fold height distribution, i.e. A W-shaped fold with legs of the same length is guaranteed, except for the edge of the leg protruding on one side.

The W folding device can also be designed in such a way that sack pack folding can be carried out over a quarter of a sack length, only one of the outer folding wedges being switched off after the sack pack being positioned on the storage rack in a correspondingly offset manner, and the gripper being designed with a corresponding clamping strip for clamping the sack pack. Basically, the stroke of the folding wedges 21 can be adjusted according to different bag lengths and the desired folding height of the W '.

After the operating folding wedges 21 according to FIG. 12 have reached their upper, ie their end position, the finished folded W stack 200 is taken over by another gripper in order to transport the ready to pack stack of W bags from the W folding device to the packing station and in suitable display packaging fill in. In its design, this gripper is matched to the shape of the folding wedges in accordance with a gripping system, that is, it is designed like a comb. Immediately after the gripper has been gripped and the W stack has been clamped, the folding wedges 21 are retracted into their starting position, ie downward, and the guide finger unit is in the starting position, thus clearing the storage rack for the next bag pack for W folding. The gripper now transports the W stack to the packing station next to the W folding device. The gripper can be part of an automatic transfer station, for example, which is equipped with two swivel arms, each with a gripper. After the folding process has ended, the grippers then take over the stack of sacks folded in an alternating rhythm. The gripper can preferably be formed in two parts, as shown in FIG. 13, with an upper rigid part 311 which takes over the W stack from the W folding device and extended outer clamping fingers 312 which are adapted to the length of the bag stack this is also recorded in full length. These extended clamping finger parts 312 are folded outwards and upwards during the stack transfer and only close in the direction of the arrow after the complete W stack has been freed from the W folding device. The actual clamping hand 311 is to be adjusted in the width of the respective sack stack width and thus the width of the display packaging, while the outer clamping fingers should grasp the sack stack up to the edge or slightly beyond the edge due to their length, so that the clean and trouble-free insertion of the Ensure W stacks in the display packaging. After the sack stack has become free from the folding device, the extended clamping fingers are pressed firmly around the W stack during the transfer by the gripper to the packing station, in order to do this to make it as flat as possible while squeezing out the air. The display packing station XVI can be designed, for example, as a wicket bag filling unit, the bags prefabricated as a display pack being hung in packs of 200 to 250 pieces in a bag pack holder, which is equipped, for example, as a double unit with a storage bag pack holder and in automatic changing operation works to maintain the continuous production operation of the plant. Such filling units are generally known. At the packing position, the bag pack receptacle is equipped with a blow nozzle that inflates the display bag at the top in the area of the flap opening and keeps it open for filling. The gripper brings the stack of W bags into the bag to be filled and tears it out of the hanging hole tear-off perforation by pushing the bag bottom forward. At the same time, the filled bag is taken over by the gripper of a second robot station, the finger surfaces of which are in turn adapted to the design of the first gripper device already described and overlap one another. The gripping device belonging to the display bag packing station pulls the completely filled bag into a closing welding station after being gripped, the other gripper withdrawing after releasing the clamping action and being ready to take over the next W stack. When the filled display bag is pulled back, it is pulled by the gripper under a smoothing brush, the air escaping from the bag and the bag opening being pulled smooth for closing. After passing the smoothing brush, the gripping device interrupts the removal of the bag, whereby the opening edge lies in the area of the welding station, which is equipped with a clamping and separation welding system and the bag is still tightly closed underneath the gripper by means of a welded seam.

After the welding process has been completed and the bag clamping in the area of the welding device has been released, the wicket hanging edge remaining above the weld seam is suctioned off with the rising welding head. At the same time, the fully filled and closed display bag is further removed from the gripping device and placed in a collecting container which, after filling, is transported to the central packaging plant, where the display bags are packed in shipping boxes.

FIG. 6p shows such a display bag 40 with a hanging tab and eyelets, which contains a stack of sacks folded in a W-shape, for example 10 garbage bags with a length of 1100 mm and a width of 700 mm and a bag size of 230 × 280 mm (without a hanging tab ).

FIGS. 18 to 21 show further variants of folded W stacks of bags.

FIG. 18 schematically shows a W-fold stack 200 with 4 folding legs 251-254 of the W-fold in a somewhat pulled-apart form. Three sacks 1 are schematically provided in the stack 200, but usually there are 10 or more, which are usually already individually folded. The stack 200 according to FIG. 18 is folded symmetrically, the two middle folding legs 252, 253 being longer than the two outer folding legs 251, 254, so that the fold 250 formed by them in the W is above the folded stack 200, ie in this case, over the two outer folding legs 251, 254 with the folded edge forming the plucked hem, protrudes. The height H of the protrusion of the fold 250, see FIG. 21, should be such that it can be accessed with the fingers can easily pull out the sack lying on top of the protruding fold in the direction of arrow A. The protrusion H, which forms the plucked hem, is approximately 15 to 30 mm.

The bags 10 are folded in so many different ways that they obtain the desired handy dimensions for the display packaging 40, that is to say widths _{S S of} the stack of approximately 10 to 30 cm and lengths L _{S of} the stack of approximately 10 to 30 cm. If the bags have a sealing tape 7 welded to the flap projecting on one side over the bag opening, which can be torn off along the perforated line 8 formed parallel thereto, are to be packed together as a folded W stack, it is advantageous to give this flap area a short sealing tape 7 to form outer folding legs of the stack 200. The accumulation of material through the fastener tape finds enough space here for accommodation due to the shorter remaining folding legs.

FIG. 19 shows a W-fold stack 200 with 6 folding legs 251-256, in which one of the folds 250 on the inside is formed with folding legs 252, 253 which are longer than the other folding legs. These fold legs are at the desired height H of the protrusion of the fold 250 over the stack, i.e. the plucked hem is longer. The stack 200 contains, for example, 20 sacks 10 which have already been individually folded by folding them twice, and which are folded together like a W, as shown in FIGS. 18 to 21. In the embodiment according to FIG. 20, one of the outer folds 250 of a W stack 200 with 4 folding legs 251-254 is formed above the other folds.

The W-shaped stack 200 unfolded according to FIG. 18 to 21 is each placed in a display packaging 40. See FIG. 22, so that the plucking hem of the protruding fold 250 is easily accessible through the removal opening 401 and an orderly removal of the sack located at the top in Arrow direction is possible.

FIG. 14 shows a partial view of a garbage bag 10 that can be produced according to the invention in the position ready for filling with a sealing tape 7 that can be torn off along the perforation 8 from the bag 10 at the bag opening 12.

The folding device according to the invention with a take-over gripper station for a display packaging device can also be used for sacks or bags made of plastic films without a welded-on sealing tape, which may even have carrying straps, in order to advantageously reduce the size by folding them up and to subsequently order them individually to enable the bags from the display packaging.

Claims (13)

1. Sack made of thermoplastic film, the front and back of which are formed from a flat film tube, characterized in that a tear-resistant sealing tape (7) made of a plastic that can be welded to the plastic film, in particular based on polyolefins, parallel to the upper edge of the bag opening and over the The width of the sack is firmly connected to at least one of the sides (1a, 1b) of the sack (10), in particular by welding, and is perforated in the area between the upper edge of the sack opening (12) and the closure band (7) connected to the sack Line (8) is formed parallel to the fastener tape (7), along which the fastener tape (7) can be torn off. 2. Sack according to claim 1
characterized in that in the case of a flap projecting on one side of the sack opening over the width of the sack in the extension of one side of the sack, the closure band (7) is firmly connected to the flap (11) parallel to the upper edge of the sack opening (12) and in In the area between the upper edge of the bag opening and the sealing tape fixed to the flap, the perforated line (8) is formed parallel to the upper edge of the bag opening, along which the sealing tape (7) can be torn off. 3. Sack according to claim 2,
characterized in that the fastener tape is welded into an envelope formed by folding over part of the flap (11). 4. Sack according to claim 1,
characterized in that the closure band (7) is inserted and welded between the two sack sides along the upper edge thereof, that the perforated line (8) is provided in both sack sides (1a, 1b) and the sack opening (12) along the perforated line (8) is trainable. 5. A process for the continuous production of bags, in particular garbage bags made of film tubes made of thermoplastic material, the extruded blown film tubes being laid flat to form tubular webs, optionally cut open in the longitudinal extension of the tubular web by at least one longitudinal cut, then the tubular web is welded crosswise and / or continuously longitudinally and optionally the weld seams are separated or cut off next to the weld seams, whereby sacks with side seams and / or bond seams are obtained and the sacks are, if necessary, stacked in sack packs and packaged into display packs, characterized in that before the weld seams are produced a continuous Tear-resistant closure tape (7), in particular made of a plastic that can be welded to the tubular web, extends in the longitudinal direction along at least one side of the tubular web (1) intended for forming the bag opening est, in particular by welding, and at least one hose web side with a perforation line (8) along which the fastener band can be torn off is formed parallel to the inner side of the fastener tape. 6. The method according to claim 5,
characterized in that the upper side of the tubular web is provided with a longitudinal section (2) offset parallel to the lower side of the tubular web by a few centimeters and the flat side is cut open along one side edge Tubular sheet (1) or semi-tubular sheet (1a, 1b) with the underlying tubular sheet side forms a protruding flap (11) on one side in accordance with the offset and the fastening tape is firmly connected to the flap and the perforation line (8) on the flap (11) between applied Closure tape and the side edge of the overhead tube sheet side is formed. 7. The method according to claim 6,
characterized in that the fastener tape is continuously applied to the flap and hemmed by turning over the flap edge and is continuously welded to the flap over the entire surface. 8. The method according to claim 5,
characterized in that the sealing tape is inserted and welded along a cut side edge of the tubular web between the two tubular web sides and the perforated line (8) next to the welded-in sealing tape (7) is formed on the inside through both tubular web pages. 9. The method according to claim 5,
characterized in that before applying the fastener tape (7) along one of the closed side edges of the flattened tubular web, instead of a separating cut, both sides of the tubular web are provided with a perforation line (8, 2a) and the fastener tape (7) into which by cutting one The flap (11) formed along the perforated line (2a) is inserted and connected to the flap by welding. 10. The method according to any one of claims 5 to 9,
characterized in that the bags equipped with the closure tape, if necessary after single or double U-folding of the individual bags in their longitudinal extent with a closed side or folded edge in The transport direction is stacked in a transverse direction at the front in a predetermined number to form a flat bag pack and the bag pack is folded into a stack in a W-like form, with either the outer folding leg of the W stack, on the edge of which the closure straps of the bags run, longer than the others folding legs are in particular of equal length, or one of the folds of the W stack is formed by two folding legs that are longer than the other folding legs, each protruding from one side above the W stack and forming a plucked hem, and the W stack is introduced into a display packaging . 11. Plant for the production of bags, in particular garbage bags, from film tubes made of thermoplastic material according to one of claims 6 to 10, containing in the production sequence an extruder with a film die head for producing the tubular film, a flat laying device for the tubular film to the tubular web, and possibly a longitudinal cutting device for the tube sheet, a storage device for the tube sheet, a film removal device for the tube sheet stored in the memory, a welding device for producing welded seams or separating welds in the transverse and / or longitudinal direction of the tube sheet for producing bags with side seams and / or bottom seams, possibly folding devices for the longitudinal folding of single bags, a bag depositing device and packaging device as well as the individual stations with a connecting means of transport, characterized in that between the film removal device (VI) and the downstream welding device (XI) for the side n- and / or bottom seams, a feed device (VIII) for placing a closure tape (7) that can be pulled off an unwinding device onto the tubular web lying on a continuously moving transport pad in longitudinal extension along a side of the tubular web with a feed funnel for the closure tape and a folding guide plate for Turning over the underlying edge of the tubular web over the attached sealing tape as well as a continuously operating connecting device (IX), in particular a rotating longitudinal welding device for welding the sealing tape to the tubular web, and a continuous longitudinal extension of the tubular web on at least one film side of the tubular web next to that by means of the connecting device (IX) producible connection of the fastening tape acting perforation device (X) is arranged to produce a linear perforation. 12. Plant for the production of stuff sacks, in particular garbage bags, from film tubes made of thermoplastic material according to claim 10, containing in the production sequence an extruder with a film die head for producing the tubular film, a lay-flat device for the tubular film to the tubular web, and possibly a longitudinal cutting device for the tubular web, one Storage device for the tubular web, a film pull-off device for the tubular web stored in the memory, a welding device for producing weld seams or separating weld seams in the transverse and / or longitudinal direction of the tubular web for producing bags with side seam and / or bottom seam, folding devices for the individual bag Longitudinal folding, a bag storage device and packaging device as well as means of transport connecting the individual stations, characterized in that the longitudinal cutting device (IV) acts as a perforation device for producing a linear perforation in parallel el is formed into a closed side edge of the tubular web and between the film take-off device (VI) and the downstream welding device (XI) for the side seams, a feed device (VIII) acting on the perforation of the upper side of the tubular web for inserting a fastener tape that can be pulled off a unwinder opened by tearing a line of perforations Flap is arranged in the longitudinal extension of the continuously transported tubular web, which is directly followed by a continuously operating connecting device (IX) for adherent connection of the fastener tape with the tubular web acting on it along the flap. 13. Plant according to one of claims 11 or 12,
characterized in that the sack storage device (XIV) is followed by a W-folding device (XV) which has a storage rack for the flat-lying sack packs and folding wedges arranged vertically through these, below the storage rack, at least 2, preferably at least 3 folding wedges, and horizontally above the storage rack and vertically movable guide fingers arranged at a gap with the folding wedges, contains at least 3, preferably at least 4, and a horizontally and vertically movable gripper which can be inserted between the folding wedges and is insertable between the folding wedges according to the shape of the shape of the folding wedges according to the engagement system W stack is arranged above the storage rack.

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