EP3323740B1 - Sealing device and method for sealing packagings - Google Patents

Description

The invention relates to a sealing device for sealing packages of the type specified in the preamble of claim 1 and to a method for sealing packages by means of such a device.

Increasingly, detergents or dishwashing detergents for domestic use are packaged in the form of powders or liquids in water-soluble packaging. The packages consist of water-soluble film and contain a unit dose of the washing or rinsing agent as a product. The filled and sealed packaging unit is placed in the washing machine or dishwasher. Upon contact with water, the film packaging dissolves and releases the contents in the quantity provided.

In the production of such a package, a base film and a cover film are used, wherein the base film or the cover film are formed from a water-soluble film web. Usually, the base film is thermoformed under the action of heat and vacuum in corresponding matrices. The molding process creates depressions in the base film, which are filled with the filling material. Subsequently, a cover sheet is sealed onto the base film. By means of the sealing of both films, the filling material contained in the molds is enclosed. Finally, the sealed packaging units are separated from the coherent film webs so that they can be used individually by the user.

For the sealing of such packages, in addition to the heat sealing method known per se for films, a water seal is also possible. In the water seal, water is applied to the cover sheet by means of a moistening unit, for example a felt roll. The moistened felt roll rolls on the water-soluble film web, whereby its surface is dissolved. The covering film with a loosened surface is then pressed onto the prepared base film by means of a pressing device, the dissolution of the film surface causing a sealing. Arrangement and method of this type are for example from the GB 2 475 538 A known.

A disadvantage of such a water-sealing process is that the amount of water applied is difficult to meter by means of the felt roll. If the water application to the water-soluble film is too great, followed by a too pronounced dissolution of the film and thus an undesirable reduction in the film thickness. As a result, the film or later the individual packages may tear in the further course of production. If, however, the amount of water applied is too small, there will be insufficient dissolution of the film surface, so that the two films do not connect properly. The packaging can consequently be leaking. But even if it is possible to set and maintain a suitable amount of water for the current operations, an adaptation to changing conditions is difficult to achieve. In the applicator roll or felt roll saturation is observed, which leads to a change in the order amount and also to contamination of the roller during the production process. This results in a deterioration of the seal. A regular machine standstill for roll change is inevitable.

In particular, in the case of a production stoppage, over-moistening usually occurs, since the film web is no longer being continued and thus is in constant contact with a constant contact zone with the felt roll. The thereby undesirably high liquid transfer to the film web and the mechanical contact with the felt roll lead to a dissolution and a subsequent tearing of the cover sheet. Even if this can be prevented, prepared, possibly filled but not yet sealed packages can not be finished sealed after a standstill, since the applied liquid dries during standstill. It creates an undesirable rejects. In addition, the unsealed product can pollute the device, so that expensive cleaning work is required.

The same is true for the same US 3,218,776 A , in which instead of a felt roll here a wick for applying water to the water-soluble film is used. From the US 2,116,995 A It is also known to spray a solvent on a cellophane film by means of spray nozzles in order to effect a dissolution of the surface for a seal. Excess solvent is doctored off using a squeegee.

The invention has the object of developing a generic sealing device such that an improved liquid application is achieved on the water-soluble film web.

This object is achieved by a sealing device having the features of claim 1.

The invention is further based on the object of specifying a method for sealing packages, by means of which a better metered moistening of the water-soluble film web can be carried out.

This object is achieved by a method having the features of claim 7.

According to the invention it is provided that the moistening unit of the sealing device as a spraying device for contactless spraying of the liquid on the formed water-soluble film web and positioned at a distance from the water-soluble film web. In the associated method, the water-soluble film web is first fed to the device, wherein a base film and / or a cover film of the packaging is formed from the water-soluble film web. Subsequently, by means of the spraying device, which is positioned at a distance from the water-soluble film web, water-containing liquid is sprayed onto the water-soluble film web. The cover film is guided onto the base film and pressed with this by means of a pressing device in the wetted state with the liquid and sealed.

The invention is based on the basic idea that no mechanical contact of the film with the moistening unit is dispensed with, and that, instead, the water-containing liquid intended for dissolving the film surface is sprayed in contactlessly. The application of the liquid can be adjusted so precisely and repeatably in terms of quantity and areal distribution by means of the spraying device that the desired degree of surface solution is exactly hit, and consequently a uniform sealing takes place along the entire film surface. This can also be reacted in a simple manner to changing boundary conditions, such as batch fluctuations in the film thickness or the like. In the production process. Another advantage is that the moistening unit is not in direct contact with the cover sheet, so that a mechanical impairment is avoided. While in the prior art, the conveying speed of the film determines the rotational speed of the rolling thereon roll of felt and thus very difficult to control or adaptation of the water supply, can be adjusted in the invention, the delivery rate of the sprayer completely independent of the movement of the film. Thus, for example, in an interruption in production, the injection process and thus the moistening of the film can be easily turned off without the cover sheet thinning excessively under an excessively high amount of liquid or even ruptures. Re-commissioning can be done without replacing the slides. This also includes the possibility of being prepared at the previous standstill, but first seal off unsealed packaging units without creating the scrap. The risk of machine pollution is reduced.

According to the invention, the spraying device comprises an electromechanical spraying system with a series of outlet nozzles for non-contact spraying of the liquid onto the water-soluble film web. This may be a bubble jet or piezo print head known, for example, from inkjet printheads. However, it is preferably an electromechanical spray system with solenoid valves, whereby water or water-containing liquids in a suitable amount, speed and distribution over a suitable distance high quality can be applied to the film web. In particular, the electromechanical valves allow the generation and application of sufficiently large drops of water. In the water supply, a suitable high pressure can be applied, which then larger spraying distances can be bridged. The opening times of the valves and the number of spray pulses are adjustable and can be adapted to the film speed. The nozzles are available with suitable diameters and can be selected depending on the application.

Accurate volume control is possible by adjusting the droplet size and timing of drop application as well as the more or less linear trajectory in connection with the synchronization of the web speed. Unlike prior art roll coating systems, the order quantity selected once remains constant, resulting in consistent seal seam strengths. The directed discharge by means of outlet nozzles allows the liquid to reach its destination precisely, without any neighboring areas getting wet. Spray mist and other harmful side effects are reliably avoided. No measures are necessary to prevent water damage such as holes in the film, foil tear, product contamination, machine damage. An otherwise required disposal of excess Water-PVA / PVOH mixture, which would lead to clogging and increased cleaning by curing and caking, is unnecessary according to the invention. This eliminates downtime, which would otherwise be caused by a change of job role, cleaning the water tank or the like.

The use of an electromechanical spray system allows in particular a variety of adjustments to the particular situation. For example, it is not limited to spray the respective film over the entire surface with liquid. Rather, the individual outlet nozzles or solenoid valves can also be individually controlled and actuated individually, which allows the dispensing of the liquid in the form of any defined patterns. For example, it is possible to limit the moistening to certain sealing contours, while the remaining film sections remain dry. As such, the film is protected, while at the same time sensitive fillings are protected from moisture. In the case of machine downtime and restart, the spray head can be swiveled to re-humidify specific areas. In this way, following a machine downtime, a virtually seamless seal can be achieved without powder or other ingredients escaping and causing dirtying the machine. Bad parts can easily be discarded without good parts being affected.

In a preferred embodiment, the sealing device comprises a squeegee having a doctor edge for wiping off the excess liquid from the water-soluble film web. Excess liquid may be removed from the cover sheet by means of the squeegee. The liquid remaining on the cover foil is distributed by means of the doctor blade in such a way that a uniform liquid film is formed on the cover foil, which improves the homogeneity of the foil seal.

Advantageously, a gap having a defined gap width is formed between the doctor edge and the film web. By adjusting the gap width, the thickness of the liquid film remaining on the film web can be set exactly and, if necessary, adjusted without further ado. Due to the fact that the doctor blade edge is not in contact with the film web, almost no mechanical forces arise, which could otherwise lead to damage of the cover film.

In an advantageous development, the squeegee comprises a suction device for sucking off the excess liquid stripped off the squeegee edge. The stripped and then aspirated liquid can for example be fed into a separate collection container or back into the liquid container. Thus, a sufficient removal of the liquid from the cover sheet can be achieved, especially at high production speeds and a high volume of liquid associated therewith.

Advantageously, the injection device is surrounded by a housing, wherein on the housing a spray window for the directed application of the liquid is formed on the water-soluble film web. By means of the spray window, the impact surface of the sprayed liquid can be defined more precisely. The housing also prevents unwanted moistening, for example, the device, attachments and the environment.

Fig. 1

in einer schematischen Seitenansicht eine nicht erfindungsgemäße Versiegelungsvorrichtung zum Versiegeln von Verpackungen mit einer Bürstenwalze als Teil einer Spritzeinrichtung zur Befeuchtung einer wasserlöslichen Folienbahn,

Fig. 2

in einer vergrößerten Detailansicht die Versiegelungsvorrichtung nach Fig. 1 mit Einzelheiten einer Rakel an einer Andrückwalze,

Fig. 3

in einer schematischen Draufsicht die Anordnung nach Fig. 2 mit Einzelheiten zu einem Absaugmechanismus in der Rakel,

Fig. 4

in einer vergrößerten Detailansicht eine erfindungsgemäße Alternative zur Versiegelungsvorrichtung nach Fig. 1 mit einem horizontal auf die obere Deckfolie gerichteten elektromechanischen Sprühsystem, und

Fig. 5

eine Variante der Anordnung nach Fig. 4, bei der das elektromechanische Sprühsystem vertikal auf die untere Basisfolie gerichtet ist.

Embodiments of the invention are described below with reference to the drawings. Show it:

Fig. 1

3 is a schematic side view of a sealing device not according to the invention for sealing packages with a brush roller as part of an injection device for moistening a water-soluble film web;

Fig. 2

in an enlarged detail view of the sealing device according to Fig. 1 with details of a doctor blade on a pressure roller,

Fig. 3

in a schematic plan view of the arrangement Fig. 2 with details of a suction mechanism in the squeegee,

Fig. 4

in an enlarged detail view of an alternative to the sealing device according to the invention Fig. 1 with an electromechanical spray system oriented horizontally on the top cover sheet, and

Fig. 5

a variant of the arrangement according to Fig. 4 in which the electro-mechanical spraying system is directed vertically onto the lower base film.

The Fig. 1 shows a schematic side view of an embodiment of a sealing device 1 according to the invention for sealing packaging 26th

The individual packages 26 comprise a base sheet 22 which is sealed with a cover sheet 5. The base film 22 and also the cover film 5 are each formed from a water-soluble film web 23, which in turn preferably consists of PVOH (polyvinyl alcohol). However, other water-soluble materials for the film web 23 may be useful. It may be provided a single film web 23, which is folded over to form the base film 22 and the cover sheet 5. In the preferred embodiment shown, a separate film webs 23 is provided for the base film 22 and also for the cover film 5. The base film 22 is suitably deep-drawn depressively before sealing, wherein the wells of the cover sheet 5 are filled with a filling material, not shown, for example, a powder or a liquid agent. However, it may also be an embodiment without plastic deformation and depression, for example in the form of a sealed tubular bag packaging be appropriate. Moreover, within the scope of the invention, embodiments are also conceivable in which only the cover film or only the base film is formed from a water-soluble film web 23.

The sealing device 1 is designed for a wet-sealing of the cover film 5 on the base film 22. For this purpose, it comprises a liquid supply for a water-containing liquid 3, at least one moistening unit for wetting the water-soluble film web 23 with the liquid 3 and a pressing device 24 for pressing and sealing the cover film 5 with the base film 22 in the wetted state with the liquid 3. With the moistening unit shown here, the film web 23 of the cover film 5 is moistened. Alternatively or additionally, however, moistening or wetting of the film web 23 of the base film 22 may also be expedient in an analogous manner.

The moistening unit is designed according to the invention as an injection device 4 for contactless spraying of the liquid 3 on the water-soluble film web 23 and positioned at a distance a to the water-soluble film web 23. The spraying device 4 may be formed by one or more spray nozzles or spray nozzles, which the water-soluble film web 23 are directed, and by means of which the water-containing liquid 3 is sprayed onto the film web 23. In the illustrated, preferred embodiment according to Fig. 1 The brushing roller 9 comprises a cylindrical roller body 10, on the circumferential side of which radially protruding bristles 11 are fastened.

The injection device 4 is fed by means of the already mentioned above and described in more detail below liquid supply with the aqueous liquid 3. For this purpose, the brush roller 9 is humidified during operation of the liquid supply. In the embodiment according to Fig. 1 the liquid supply is shown as a liquid container 2 with the water-containing liquid 3 therein, the liquid forming a liquid gel 13. The brush roller 9 is positioned opposite to the liquid container 2 so that the bristles 11 reach below the liquid control gel 13 and consequently submerge in the liquid 3 located in the liquid container 2. By not shown control means is achieved that in operation, the height of the liquid level 13 and thus the immersion depth of the bristles 11 in the liquid 3 remains substantially constant. Alternatively or in addition to the liquid container 2, however, it is also possible for example to provide a water line from which a direct moistening of the brush roller 9 takes place. The hydrous liquid 3 may be simple tap water, water provided with surfactants, or the like. In any case, its water content must be so high that it dissolves on contact the surface of the water-soluble film web 23.

As a result of the rotational movement of the brush roller 9, the liquid 3 taken up by the bristles 11 is thrown off. The amount of liquid thrown off from the brush roller 9 can be made, for example, by adjusting the immersion depth of the bristles 11 into the liquid 3, ie by height adjustment of the brush roller 9 and / or height adjustment of the liquid level 13 and by selecting a suitable speed of the brush roller 9. The film web 23 to be moistened, here by way of example the film web 23 from which the cover sheet 5 is formed, is passed to the brush roller 9 at a distance a so that the centrifuged liquid 3 splashes against the cover sheet 5. The cover film 5 moistened with the liquid 3 and thus dissolved on its surface is brought together with the base film at the pressing device 24 and compressed, the loosened film surface, in conjunction with the applied pressing pressure, sealing the cover film 5 with the base film 22. For the generation of the pressing pressure is in the embodiment according to Fig. 1 the pressing device 24 is designed as a pressure roller 6 rotating about an axis of rotation 12, by means of which the cover film 5 is sealed under pressure onto the underlying base film. However, the pressing device 24 may also comprise, for example, two pressing plates pressing against each other. In addition, it may optionally include an additional heating station so that a combined wet and heat seal takes place.

The optional scraper 15 already mentioned above is arranged on the side of the brush roller 9 facing the film web 23 to be moistened so that it protrudes with its scraper edge 16 between the bristles 11, that is to say into the imaginary wrapping cylinder of the bristles 11. During the rotation of the brush roller 9, the bristles 11 contact the wiping edge 16 of the wiper 15 and are bent back against the direction of rotation of the brush roller 9 at the wiping edge 16. Upon further rotation, the bent-back bristles 11 slide past the wiping edge 16, align themselves under the action of centrifugal force and resilient restoring force, and inject the liquid 3 taken in the direction of cover sheet 5. The resilient recoil of the bristles 11 supports the already existing centrifugal force during the centrifuging of the Liquid 3 and also gives the spun liquid a defined injection direction. By selecting or setting a suitable relative positioning of the scraper 15 to the brush roller 9, in addition to the amount of liquid to be dispensed, in particular the spray direction of the liquid 3 and thus the impact area on the film web 23 can be adjusted.

In Fig. 1 is still recognizable that the spraying device 4 is surrounded by a housing 7, which serves among other things as a splash guard against the environment. In the housing 7, a spray window 8 is formed, which is positioned between the spray device 4 and the film web 23 that a directed spraying of the liquid 4 is supported on a specific target surface of the film web 23 by means of the brush roller 9. Optionally, an adjustment for size and relative position of the spray window 8 may be provided.

In the preferred embodiment shown, the sealing device also comprises a doctor blade 17 with a doctor blade edge 18, wherein the doctor blade edge 18 is positioned immediately adjacent to the film web 23. Based on the direction of passage of the film web 23, the doctor blade edge 18 is subsequently positioned to the impact zone of the sprayed-on liquid 3 and arranged so that the doctor blade edge 18 wipes off the excess liquid 3 from the film web 23. As a result of a suitable design and positioning of the doctor blade 17 and its doctor edge 18, optionally supported by further described below drainage or suction, the stripped from the cover sheet 5 liquid 3 is collected, and can for example in a separate receptacle or back into the liquid container 2 are guided.

Fig. 2 shows in an enlarged detail view of the sealing device after Fig. 1 in the area of the doctor blade 17 and the pressure roller 6. In the preferred embodiment shown, the doctor blade 17 is positioned so that the doctor blade edge 18 is adjacent to the film web 23, where the film web 23 wraps around the pressure roller 6, preferably at the beginning of the wrapping. Although the blade edge 18 directly adjoins the film web 23, but it is not in touching contact with the film web 23. Rather, a gap with a defined gap width b remains between the doctor edge 18 and the facing surface of the film web 23. As a result of the gap width b on the one hand excess liquid 3 from the surface of the film web 23 without contact, so scraped without mechanical stress on the film web 23, while on the other hand predetermined in thickness by the gap width b Liquid film on the surface of the film web 23 remains. Thus, the amount of liquid 3 is precisely predetermined on the surface of the film web 23 and their dissolution effect. The gap width b can be adjusted in particular by suitable positioning means, not shown here, of the doctor blade edge 18 with respect to the peripheral surface of the pressure roller 6.

Fig. 3 shows still in a schematic plan view of the arrangement Fig. 2 with the doctor 17 and the pressure roller 6. From the synopsis of Fig. 2 and 3 results in that in the doctor blade 17 a collecting channel 25 is formed, is collected in the stripped liquid 3. In the bottom of the collecting channel are drain openings 14. Through the drain openings 14, the collected liquid 3 can passively pass. In the preferred embodiment shown, the collecting channel 25 and the discharge openings 14 are part of a suction device 19, by means of which the collected liquid 3 is actively sucked by the doctor 17 and forwarded.

Fig. 4 shows in a perspective detail view of an alternative to the sealing device 1 according to the Fig. 1 to 3 , Instead of the previously described brush roller 9, the spraying device 4 here comprises an electromechanical spraying system 30. The electromechanical spraying system 30 has a number of outlet nozzles 31, this row extending transversely across the cover sheet 5 and shown here only in block form for the sake of simplicity. The outlet nozzles 31 are directed to the later surface of the cover film 5 facing the base film 22, specifically where the cover film 5 wraps around the pressure roller 6. In operation, the aqueous liquid 3 is sprayed by means of the electromechanical spray system 30 and its series of outlet nozzles 31 contactlessly on the cover sheet 5, to which each individual outlet nozzle 31 each forms a droplet stream 33. The droplet jets 33 impinge on the cover film 5 at a sufficiently close distance, so that a closed film of the liquid 3 forms there. Alternatively, however, by targeted control or actuation of the individual outlet nozzles 31, a specific Befeuchtungsmuster be achieved. In any case, the cover film 5 moistened in this way and thus loosened on its surface is rolled under pressure by means of the pressure roller 6 onto flat sealing sections 27 of the base film 22. Since very precisely measured quantities of liquid can be applied, an intimate seal is produced between the cover film 5 and the base film 22 at the sealing portions 27 even after a very short exposure and drying time, as a result of which tightly sealed packages 26 are formed. Although it is not absolutely necessary according to the invention, the pressure roller 6 can additionally be heated in order to accelerate the sealing process.

According to the schematic block diagram according to Fig. 4 Each individual outlet nozzle 31 is associated with one respective lifting magnet valve 32, so that in each case one outlet nozzle 31 and one associated lifting solenoid valve 32 are available for forming all the droplet jets 33. Instead of the solenoid valves 32 but also bubble jet units or piezo units can be used, as they are known in the art of ink jet printers. The solenoid valves 32 are individually controlled or actuated by means of a suitable, not shown in detail control unit, whereby a flat film moistening, but also any Befeuchtungsmuster are possible. Such a moistening pattern could, for example, correspond to the pattern of the sealing portions 27. It is then actually provided there only a loosened film surface for sealing, where the cover sheet 5 strikes the base sheet 27, while the cover sheet 5 remains dry, where it covers the filled into the deep-drawn cavities product filling. By suitable control, a synchronization of the liquid application with the feed rate of the cover sheet 5 and / or the base film 22 is possible.

In the illustration after Fig. 4 Only one unit or a single printhead is shown as an electromechanical spray system 30, wherein the outlet nozzles 31 and the droplet jets 33 generated thereby are aligned horizontally by way of example. to Overvoltage larger film widths, so if the film width is greater than the useful width of a single printhead, an overlapping nesting of several such printheads can be useful. These can then be pivoted relative to each other with respect to their beam direction so that the droplet beams 33 impinge along a common line. In this way, a uniform liquid wetting is possible even with very large film widths. By an active, controlled pivoting of the electromechanical spray system 30 and the impact of the droplet jets 33 can be changed or adjusted, whereby, for example, following a machine downtime targeted re-wetting of the films and thus a complete seal is possible.

A variant of the arrangement and the method according to Fig. 4 is in Fig. 5 shown. Here, the electromechanical spray system 30 is oriented such that the droplet jets 33 do not strike the cover sheet 5 but the base film 22. The outlet nozzles 31 ( Fig. 4 ) are directed vertically downwards. But it can also be an oblique orientation appropriate. To Fig. 5 is such a control of the outlet nozzles 31 and the solenoid valves 32 (FIG. Fig. 4 ) and also such a synchronization with the advance of the base film 22 that only the flat upper sealing sections 27 with liquid 3 (FIG. Fig. 4 ). The intermediate cavities filled with product material are excluded from moisture spray. In particular, with filling materials with low sensitivity to moisture but also a full-surface Flüssigkeitsbesprühung the lower base film 22 may be appropriate, in which case it is tolerated that at this time still exposed product filling is acted upon with a small amount of liquid. In the remaining features and reference numerals, the embodiments agree with the 4 and 5 with each other and with the embodiment of the Fig. 1 to 3 match.

Claims (7)

1. Sealing device for sealing packagings, wherein the packaging comprises a base film (22) and a cover film (5), wherein the base film (22) and/or the cover film (5) is/are formed from a water-soluble film web (23), wherein the device comprises a liquid supply for an aqueous liquid (3), at least one wetting unit for wetting the water-soluble film web (23) with the liquid (3), which wetting unit is positioned at a distance (a) from the water-soluble film web (23), and a pressing-on device (24) for pressing and sealing the cover film (5) to the base film (22) when wetted with the liquid (3),
   characterised in that the wetting unit is designed as a spraying device (4) for the contactless spraying of the liquid (3) onto the water-soluble film web (23), and in that the spraying device (4) comprises an electromechanical spraying system (30) with a row of discharge nozzles (31) for the contactless spraying of the liquid (3) onto the water-soluble film web (23).
2. Sealing device according to claim 1,
   characterised in that the electromechanical spraying system (30) has a row of solenoid valves (32) assigned to the discharge nozzles (31).
3. Sealing device according to claim 1 or 2,
   characterised in that the sealing device (1) comprises a doctor blade (17) with a blade edge (18) for wiping the surplus liquid (3) off the water-soluble film web (23).
4. Sealing device according to claim 3,
   characterised in that a gap with a defined gap width (b) is formed between the blade edge (18) and the water-soluble film web (23).
5. Sealing device according to claim 3 or 4,
   characterised in that the doctor blade (17) comprises an extraction device (19) for extracting the surplus liquid (3) wiped off by the blade edge (18).
6. Sealing device according to any of claims 1 to 5,
   characterised in that the spraying device (4) is surrounded by a housing (7), wherein a spraying window (8) for the directed application of the liquid (3) to the water-soluble film web (23) is formed at the housing (7).
7. Method for sealing packagings by means of a sealing device (1) according to any of claims 1 to 6, comprising the following steps:

   - a water-soluble film web (23) is fed to the sealing device (1), wherein a base film (22) and/or a cover film (5) of a packaging is/are formed from the water-soluble film web (23),

   - a spraying device (4) is positioned at a distance (a) from the water-soluble film web (23),

   - an aqueous liquid (3) is sprayed onto the water-soluble film web (23) by means of the spraying device (4),

   - the cover film (5) is guided onto the base film (22) and pressed and sealed thereto by means of a pressing-on device when wetted with the liquid (3).

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