EP3749514B1 - Method and apparatus for joining paper material - Google Patents

Description

State of the art

The present invention relates to a method and a device for joining paper material, in particular paper, cardboard or cardboard or the like, wherein the joining process can be carried out without additional auxiliary materials, in particular free of plastic and / or adhesive.

From the EP 0 340 334 A2 a device is known which joins paper products by means of ultrasound. The paper used here is thermoplastic Coating on. This thermoplastic coating is melted on during the joining process. After cooling and hardening, the joining areas of the paper layers are then connected to one another. Furthermore, from the DE 10 2013 225 745 A1 an ultrasonic joining method for joining paper material is known in which ultrasonic friction welding is carried out. These known methods have basically proven themselves, but there is an urgent need, in particular due to stricter environmental regulations, that packaging, for example, be made entirely from paper material that is recyclable and no other additional ingredients, in particular plastics or adhesives or the like, which can result in environmental pollution , contains.

DE 10 2013 225737 describes a method for producing a packaging from paper material with the following steps: Forming a packaging from a blank of paper material, wherein the paper material overlaps at at least one joint. Positioning the at least one joint between a sonotrode and an anvil, applying a joining force to the joint (21) in a joining force direction, and setting the sonotrode in ultrasonic vibration for ultrasonic welding of the paper material at the joint, the paper material being moistened before the packaging is formed will. JP 2007 126249 A describes a corrugated sheet manufacturing apparatus employing a conventional ultrasonic joining process, along with one of the three Alternatives: moistening the joining areas, a thermoplastic film as joining material and roughening the joining areas.

Disclosure of the invention

The method according to the invention for joining paper materials with the features of claim 1 has the advantage that, for example, untreated paper material can be used to produce packaging. This is achieved according to the invention in that the method for joining paper material, which has a first and second joining area, comprises the following steps: roughening the first and / or second joining area, moistening the first and / or second joining area and joining the first and second Joining area between a sonotrode and an anvil of an ultrasonic unit by means of ultrasonic friction welding, a direction of vibration of the sonotrode not being parallel to a joining force direction of a joining force. In this case, the first and second joining areas can be provided on a single paper material, or one joining area in each case is provided on a separate paper material. The roughening of the joint area ensures that a three-dimensional enlargement of the joint surface is achieved on the joint surface. The additional provision of water on the joining surface enables a hydrogen bridge to be bonded during the joining process. The joining process is carried out by means of pressure and ultrasound. The clever idea of roughening the paper surface increases the strength of the connection created. When roughening, individual paper fibers are released from the paper composite and brought to the surface of the joint area. This increases the roughness of the joining surface.

The method according to the invention can be carried out in various ways.

In a first step, the joining area of the paper material is preferably roughened and then the roughened joining area is moistened with water or another liquid. The second joining area remains untreated. The joining process can then be carried out.

Alternatively, the first joining area is roughened and the second joining area is moistened. The roughened joint area and the second moistened joint area are then joined together.

According to a further alternative, the first joining area of the paper material is moistened and then the moistened first joining area is roughened. The second joining area can remain untreated or alternatively be roughened or alternatively only moistened or further alternatively both roughened and moistened.

Due to the heat introduced during the ultrasonic friction welding, the water applied by the moistening evaporates and a stable connection between the two paper materials can be achieved.

The invention is particularly preferably carried out only on the first joining area, further preferably first roughening and then moistening. As a result, the second joining area can be left untreated and a joining process can then be carried out.

By carrying out the roughening before the joining step, a significantly improved connection between the two joining areas of the paper materials is achieved. The step of roughening is preferably carried out by machine, so that a constant roughening of the joining area is always achieved.
The subclaims show preferred developments of the invention.

A particularly good ultrasonic friction welding process is preferably ensured if a vibration direction of the sonotrode is perpendicular or essentially perpendicular to the direction of the joining force. This ensures a high input of energy into the joining area, so that the joining time can be significantly shortened.

The process is preferably carried out continuously. This can, for example, create a closed seam, which is used in particular in packaging or the like, are generated. The continuous execution of the process also ensures a linear joint connection in the joint areas. Alternatively, the method is carried out discontinuously if, for example, no closed joint is to be established.

Particularly good joining results are obtained if the roughening of the first joining area and / or the second joining area is carried out in such a way that a roughness in a range of ± 20 μm, in particular ± 10 μm, around a center plane of the paper material is achieved. As a result, an essentially constant roughening of the surface of the joining area can be achieved, which leads to excellent joining results.

A width of the roughened joining area is also preferably equal to a width of the moistened joining area. The joining process is more preferably carried out completely without additives, in particular thermoplastics or adhesives or the like. In particular, the paper materials to be joined are free of plastic and adhesive. Furthermore, the paper materials do not have any plastic coating or the like.

A particularly compact device for carrying out the method is achieved if the step of roughening is also carried out by means of ultrasound. Here you can then two ultrasonic units are arranged one after the other, the first ultrasonic unit for roughening at least one joining area and the second ultrasonic unit then for carrying out the joining step.

The roughening is preferably carried out continuously or alternatively discontinuously. If the roughening is to be carried out by means of ultrasound, a sonotrode of an ultrasonic unit is preferably designed in such a way that the sonotrode has a flat sonotrode surface directed towards the paper material. As a result, excellent roughening can be obtained in a predetermined band area.

• eine Aufrauvorrichtung zum Aufrauen wenigstens eines Fügebereichs eines Papiermaterials,
• eine Befeuchtungsvorrichtung zum Befeuchten wenigstens eines Fügebereichs des Papiermaterials und
• eine Ultraschall-Reibschweißvorrichtung mit einer Sonotrode zur Erzeugung einer UltraschallSchwingung und einem Amboss zur Erzeugung einer Fügekraft, wobei die Fügekraft in eine andere, unparallele Richtung gerichtet ist, als eine Richtung der Ultraschall-Schwingungen der Sonotrode.

The present invention also relates to a device for joining paper materials

• a roughening device for roughening at least one joining area of a paper material,
• a moistening device for moistening at least one joining area of the paper material and
• an ultrasonic friction welding device with a sonotrode for generating an ultrasonic oscillation and an anvil for generating a joining force, the joining force being directed in a different, non-parallel direction than a direction of the ultrasonic oscillations of the sonotrode.

Thus, the ultrasonic friction welding device ensures that a vibration direction of the sonotrode and a joining force direction of the joining force are not parallel and thus an increased heat input is achieved by the ultrasonic friction welding process.

The anvil is preferably a roller or roller. In this way, a different direction between the joining force or the roughening force and the direction of vibration can be achieved in a simple manner.

The roughening device is more preferably an ultrasonic generator. A separate ultrasound generator is preferably used here.

According to a further preferred embodiment of the invention, the roughening device ensures a roughness which is in a bandwidth of ± 20 μm, preferably ± 10 μm.

The present invention also relates to a paper packaging which is produced by the method according to the invention. When the joining area of the paper packaging was roughened, individual paper fibers were detached from a paper bundle of the paper packaging and brought to the surface of the joining area.

The paper packaging is particularly preferably a food packaging. Since the paper packaging is plastic-free and free of other foreign matter the paper packaging is completely recyclable.

• Figur 1 eine schematische Darstellung einer Vorrichtung zum Fügen gemäß einem ersten Ausführungsbeispiel der Erfindung,
• Figur 2 eine schematische Darstellung einer Aufrauvorrichtung des ersten Ausführungsbeispiels,
• Figur 3 ein Diagramm, welches schematisch die Rauheit des aufgerauten Fügebereichs des ersten Ausführungsbeispiels darstellt,
• Figur 4 eine schematische Ansicht einer Ultraschall-Schweißvorrichtung gemäß dem ersten Ausführungsbeispiel,
• Figur 5 eine schematische Darstellung des Verfahrens zum Fügen gemäß dem ersten Ausführungsbeispiel,
• Figur 6 eine schematische Darstellung eines Verfahrens zum Fügen gemäß einem zweiten Ausführungsbeispiel,
• Figur 7 eine schematische Darstellung eines Verfahrens zum Fügen gemäß einem dritten Ausführungsbeispiel,
• Figur 8 eine schematische Darstellung eines Verfahrens zum Fügen gemäß einem vierten Ausführungsbeispiel,
• Figur 9 eine schematische Darstellung eines Verfahrens zum Fügen gemäß einem fünften Ausführungsbeispiel, und
• Figur 10 eine schematische Darstellung eines Verfahren zum Fügen gemäß einem sechsten Ausführungsbeispiel.

Preferred embodiments of the invention:
Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing is:

• Figure 1 a schematic representation of a device for joining according to a first embodiment of the invention,
• Figure 2 a schematic representation of a roughening device of the first embodiment,
• Figure 3 a diagram which schematically shows the roughness of the roughened joining area of the first embodiment,
• Figure 4 a schematic view of an ultrasonic welding device according to the first embodiment,
• Figure 5 a schematic representation of the method for joining according to the first embodiment,
• Figure 6 a schematic representation of a method for joining according to a second embodiment,
• Figure 7 a schematic representation of a method for joining according to a third embodiment,
• Figure 8 a schematic representation of a method for joining according to a fourth embodiment,
• Figure 9 a schematic representation of a method for joining according to a fifth embodiment, and
• Figure 10 a schematic representation of a method for joining according to a sixth embodiment.

Preferred embodiments of the invention

In the following, with reference to the Figures 1 to 5 an apparatus 1 and a method for joining paper material according to a first exemplary embodiment of the invention are described in detail.

Figure 1 shows schematically the structure of the device 1 for joining paper material. How out Figure 1 As can be seen, the device 1 comprises a roughening device 4, a moistening device 5 and an ultrasonic friction welding device 6.

In this exemplary embodiment, a first paper material 2 and a second paper material 3 are to be joined to one another at a joining area, in particular an edge area of the paper materials. The paper materials can, for example, be pulled off a roll as continuous goods. The paper materials are plastic-free and adhesive-free and have no coating whatsoever.

A first joining area 20 is provided on the first paper material 2. A second joining area 30 is provided on the second paper material 3. This is shown schematically in the illustration of the method according to the invention according to the first exemplary embodiment in FIG Figure 5 shown.

In the first exemplary embodiment, only the first joining area 20 is treated with a plurality of method steps, whereas the second joining area 30 remains without treatment. I. E. the second joining area 30 corresponds to the surface of the flat paper material.

As from the Figures 1 and 5 As can be seen, the first paper material 2 is pulled off the roll and fed to the roughening device 4. Here, the first joining area 20 is roughened.

In this exemplary embodiment, the roughening device 4 is an ultrasonic roughening device, which is shown in detail in FIG Figure 2 is shown. The roughening device 4 comprises a flat sonotrode 70, which is made to vibrate by means of a double converter 71. Furthermore, the roughening device 4 comprises a flat anvil 73. The flat sonotrode 70 has a horizontal oscillation direction A. The anvil 63 provides a joining force in a joining force direction B which is perpendicular to the sonotrode oscillation A. For better Clarity is in Figure 2 the first paper material 2, which is roughened at the first joining area 20, is not shown.

Figure 3 shows a diagram which shows the roughness of the first joining area 20 after the roughening process. Here it becomes clear that the ultrasonic roughening has a roughening with a height profile of approx. 20 µm, which has point elevations and depressions between +10 µm and -10 µm. The diagram shows the roughness R over the run length L of the first paper material 2.

When roughening by means of the roughening device 4, the roughness of the surface of the first joining area 20 can be influenced in a targeted manner via the oscillation duration and the oscillation amplitude. The longer the period of oscillation, the more the surface of the first joining area 20 is changed and roughened. If the amplitude of the vibration of the sonotrode is reduced, the bonded joint becomes less peelable.
A contact surface of the sonotrode 70 with the first paper material 2 is preferably somewhat roughened, for example by means of glass bead blasting, so that better results are obtained during the roughening process.

Figure 4 shows the ultrasonic friction-welded connection 6, with an anvil 63 in the form of a roller being provided. An oscillation direction A of the sonotrode 70 is perpendicular to a joining force direction B of the roller-shaped anvil 63. This can generate a great deal of heat so that the joining process can be carried out using ultrasonic friction welding. It should be noted that the in Figure 4 The device shown can also be used as a variant of a roughening device.

How out Figure 1 and 5 It can also be seen that the first joining area 20 is moistened by means of the moistening device 5 before the actual joining process. The preferred medium for moistening is water. Since the first joining area 20 was roughened by the roughening device 4 before it was moistened, the result is a three-dimensional enlargement of the joining surface, which, in the presence of water, enables an improved hydrogen bridge bond during joining compared to a non-roughened surface due to the moistening.

In particular, no additives or plastic coatings of the paper materials 2, 3 or the like are possible due to the roughening process. Untreated paper materials can be used for the joining process. As a result, the method according to the invention can be used universally.

Figure 5 shows again schematically the process sequence of the joining process of the first and second paper material 2, 3. In the first step, the first joining area 20 is roughened by the roughening device 4, so that a roughened first joining area 201 is created. The second joining area 30 remains untreated.

In the next step, the roughened first joining area 201 is moistened by means of the moistening device 5. This creates a roughened, moistened first joining area 202. The second joining area 30 continues to remain untreated.

The two paper materials 2, 3 are then fed to the ultrasonic friction welding device 6 and the connection 11 between the first and second paper material is established by ultrasonic friction welding. The roughening and moistening of the first joining area 20 enables an excellent connection of paper materials. The second joining area 30 did not have to be processed in any way. As a result, this method according to the invention can be carried out particularly cost-effectively.

Figure 6 shows schematically a method for joining paper materials according to a second embodiment of the invention. Identical or functionally identical parts are denoted by the same reference symbols. In contrast to the first exemplary embodiment, in the second exemplary embodiment the second joining area 30 is also processed. How out Figure 6 As can be seen, the first joining area 20 is roughened in a first step by means of the roughening device 4. At the same time, the second joining area 30 is moistened by means of a moistening device 5. The first and second paper material 2, 3 are then fed to the ultrasonic friction welding device 6 and joined to one another. With this structure For example, the first joining area 20 and the second joining area 30 can be treated in parallel, so that a particularly compact joining device 1 is possible.

Figure 7 shows a method according to a third embodiment of the invention. The method for the first joining area 20 of the first paper material 2 according to the third exemplary embodiment corresponds to the first exemplary embodiment, so that in a first step the first joining area 20 is first roughened and then moistened. In contrast to the first
In the third embodiment, however, the second joining area 30 is also dealt with. How out Figure 7 As can be seen, the second joining area 30 is roughened by means of a second roughening device 4 ′, so that a roughened, second joining area 302 is produced. In the last step, the roughened second joining area 302 and the roughened and moistened first joining area 202 are then connected to one another in the ultrasonic friction welding device 6.
Figure 8 shows a method according to a fourth embodiment, in which the first joining area 20 is processed by roughening and moistening as in the first embodiment and the second joining area 30 is first moistened by means of a second moistening device 5 'and then roughened with a second roughening device 4'. Thus, the sequence of roughening and moistening in the first and second joining areas 20, 30 is reversed. In the last step, the two joining areas of the first and second paper material 2, 3 then joined again to form a joined paper material 10 by means of the ultrasonic friction welding device 6. It should be noted here that the order of roughening and moistening, as in Figure 8 shown schematically, can also be reversed.

Figure 9 shows a method according to a fifth embodiment of the invention. In the fifth exemplary embodiment, both the first joining area 20 and the second joining area 30 are processed. How out Figure 9 As can be seen, the first joining area 20 and the second joining area 30 are both moistened in a first step by means of moistening devices 5, 5 'and then roughened in a second step by means of roughening devices 4, 4'. In the last step, the joining process is carried out again by means of the ultrasonic friction welding device 6. The first joining area 20 is thus moistened first, so that a moistened first joining area 203 is created, which is then roughened so that a moistened and roughened first joining area 202 is created. In the same way, the second joining area 30 is first moistened so that a moistened second joining area 301 is created and then roughened so that a moistened and roughened second joining area 303 is created. The two joining areas are then joined again to form a joined paper material 10.
Figure 10 shows a method according to a sixth embodiment of the invention. Here, the first and second joining areas 20, 30 are on a single one Paper material 2 is provided and is joined to form a tubular bag 200 with a longitudinal seam 210. The first joining area 20 is roughened and the second joining area 30 is moistened.

For the production of a tubular bag it should be noted that the in the Figures 6 to 9 The variants described can also only be implemented with a single paper material with first and second joining areas 20, 30.

It should also be noted for all exemplary embodiments that it is possible according to the invention that different variants of the invention can be carried out as long as at least one moistening step and one roughening step on one or both joining areas 20, 30 of the
Paper materials 2, 3 is executed.

Claims (17)

1. Method for joining paper material (2, 3) at a first joining area (20) and a second joining area (30), comprising the steps:

   - moistening the first joining area (20) and/or the second joining area (30) and

   - joining the first and the second joining area (20, 30) between a sonotrode (60) and an anvil (63) of an ultrasonic friction welding device (6) by means of ultrasonic friction welding, wherein a direction of oscillation (8) of the sonotrode (60) is not parallel to a direction of joining force (B) of a joining force of the anvil (63),
   characterized in that the method comprises the step:

   - roughening of the first joining area (20 and/or the second joining area (30).
2. Method as claimed in claim 1, wherein the step of roughening of the first and/or the second joining area is performed before the moistening step.
3. Method as claimed in claim 1, wherein the step of roughening of the first and/or the second joining area is performed after the moistening step.
4. Method as claimed in one of the preceding claims, wherein the direction of oscillation (A) is orthogonal to the direction of joining force (B).
5. Method as claimed in one of the preceding claims, wherein the method is performed continuously so that a joint connection (11) in form of a line is produced on the paper material.
6. Method as claimed in one of the preceding claims, wherein the roughening is performed in such a way that a roughness in a bandwidth of 20 µm, in particular 10 µm between point-shaped raised parts and recesses is reached with a uniform gradient.
7. Method as claimed in one of the preceding claims, wherein a width of the roughened joining area is the same as a width of the moistened joining area.
8. Method as claimed in one of the preceding claims, wherein joining is performed entirely without additional agents, in particular plastics or adhesives.
9. Method as claimed in one of the preceding claims, wherein the paper material to be joined is free of plastics and free of adhesives.
10. Method as claimed in one of the preceding claims, wherein the roughening step is performed by means of ultrasonic sound.
11. Method as claimed in one of the preceding claims, wherein roughening is performed continuously or discontinuously.
12. Device for joining paper material (2, 3) at joining areas (20, 30) of the paper material, comprising

    - a moistening device (5) for moistening the joining area (20, 30) and

    - a supersonic friction welding device (6) comprising a sonotrode (60) for generating a supersonic oscillation and an anvil (63) for generating a joining force, wherein the supersonic oscillation is directed in a first direction (A) which is not parallel to a direction of force (B) of the joining force of the anvil,
    characterized in that

    - the device comprises a roughening device (4) for roughening a joining area (20, 30) of the paper material.
13. Device as claimed in claim 12, wherein the anvil is formed as a roller or drum.
14. Device as claimed in claim 12 or 13, wherein the roughening device (4) is operated by means of supersonic sound.
15. Device as claimed in one of claims 12 to 14, wherein the roughening device (4) generates a roughness in a bandwidth of 20 µm, in particular 10 µm which has a uniform gradient.
16. Device as claimed in one of claims 14 or 15, wherein a sonotrode (60) of the roughening device (4) is in the form of a plane and comprises a roughened surface.
17. Paper packaging having a connection made according to a method as claimed in one of claims 1 to 11, wherein during roughening of the joining area single paper fibers are loosened from a paper binding of the paper packaging and fetched to the surface of the joining area.

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