DE102024202007A1 - Method for producing a seal and/or adhesive structure on a substrate - Google Patents

Abstract

The invention relates to a method for producing a seal (1) and/or adhesive structure on a substrate (2), in particular on a layer or ply of an electrochemical cell, by means of stencil printing, comprising the steps:
a) placing the substrate (2) on a printing table (10),
b) bringing the substrate (2) into contact with a one-part stencil (3) or at least one stencil part (3.1, 3.2, 3.3) of a multi-part stencil (3),
c) fixing the position of the template (3) or of the at least one template part (3.1, 3.2, 3.3) with respect to the substrate (2),
d) filling at least one recess (4) of the single-part or multi-part stencil (3) with a sealant and/or adhesive (6) in a doctor blade process and
e) releasing the sealant and/or adhesive (6) from the at least one recess (4).
According to the invention, the fixing of the position of the template (3) or of the at least one template part (3.1, 3.2, 3.3) with respect to the substrate (2) in step c) is effected by means of a magnetic or suction force which draws the template (3) or the at least one template part (3.1, 3.2, 3.3) in the direction of the substrate (2).

Description

The invention relates to a method for producing a seal and/or an adhesive structure on a substrate, in particular on a layer or ply of an electrochemical cell, for example a fuel cell, electrolysis cell, or battery cell. The layer or ply can be, in particular, a monopolar or bipolar plate, a separator plate, and/or a membrane-electrode assembly. Furthermore, the method can be used to produce a seal and/or adhesive structure on many other substrates, such as a housing part.

State of the art

Electrochemical cells, such as fuel cells, electrolysis cells, or battery cells, have a multi-layered structure. This structure requires intermediate seals to separate the media supplied to a cell during operation. To form the seals, a sealant and/or adhesive is applied to a layer or ply of the cell. Dispensing or printing processes are particularly used for this purpose.

1. 1. Applizieren eines Dicht- und/oder Klebstoffs auf einer auf dem zu bedruckenden Substrat aufliegenden Schablone,
2. 2. Befüllen mindestens einer Ausnehmung der Schablone mit dem Dicht- und/oder Klebstoff in einem Rakelprozess,
3. 3. Auslösen des Dicht- und/oder Klebstoffs aus der mindestens einen Ausnehmung durch Trennen von Substrat und Schablone.

The mass production of electrochemical cells requires high processing speed, meaning short cycle times, as well as high process stability. Stencil printing, in particular, meets these requirements. The stencil printing process is essentially divided into the following three subprocesses:

1. 1. Applying a sealant and/or adhesive to a stencil placed on the substrate to be printed,
2. 2. Filling at least one recess of the stencil with the sealant and/or adhesive in a squeegee process,
3. 3. Releasing the sealant and/or adhesive from the at least one recess by separating the substrate and the stencil.

The stencil height determines the layer height of the applied structure, with typical layer heights ranging from 100 µm to 300 µm. However, for seals in electrochemical cells, layer heights of up to 1500 µm are required to allow for tolerance compensation and greater freedom in the design of the applied structure. Depending on the specific sealing concept, the structures to be applied can be large and/or complex.

In order to achieve the layer heights required for electrochemical cell seals during stencil printing, higher stencils must be used. However, this increases the risk of air bubbles forming during the squeegee process, which prevent the complete filling of at least one stencil recess and thus lead to defects in the printed structure. The larger the volume of the at least one recess to be filled with sealant and/or adhesive, the greater the risk of bubble formation. If the at least one recess is spanned by at least one web to stabilize the stencil, the risk of bubble formation increases further. This is exemplified in the 1a) and 1b) shown. 1 shows a stencil 3 resting on a substrate 2 with a recess 4, which is bridged by webs 5. To fill the recess 4 with a sealant and/or adhesive 6, a squeegee 7 is drawn over the stencil 3 in a predetermined squeegee direction (see arrow). 1b) As shown, an air bubble 8 can form in front of a web 5 in the squeegee direction.

However, bubble formation can occur not only when filling the at least one stencil recess with the sealant and/or adhesive, but also when the sealant and/or adhesive is released. This applies in particular if the stencil recess is spanned by webs. Because - as exemplified in the 2a) to 2e) As shown, sealant and/or adhesive 6 can adhere to the underside of the webs 5 and, when released, form threads 9. The threads 9 are pulled or stretched until they tear or detach from the underside of the web. When the threads 9 collapse, air bubbles 8 can then form.

Webs are particularly needed when the structure to be printed, and thus at least one recess of the stencil, has a closed contour. In this case, the stencil has at least two parts, namely at least one outer and one inner part. Such a multi-part stencil is exemplified in the 3 It has an outer part 3.1 and two inner parts 3.2, 3.3. Parts 3.1, 3.2, and 3.3 are connected to each other via webs 5.

Since webs can negatively influence the quality of the printed structure, the present invention is concerned with the object of providing a method for producing a seal and/or an adhesive structure by means of stencil printing, which enables the use of a stencil without webs, in particular when the structure to be produced is a seal with an endless contour.

To achieve this object, the method having the features of claim 1 is proposed. Advantageous further developments of the invention can be found in the subclaims.

Disclosure of the invention

1. a) Auflegen des Substrats auf einen Drucktisch,
2. b) Inkontaktbringen des Substrats mit einer einteiligen Schablone oder mindestens einem Schablonenteil einer mehrteiligen Schablone,
3. c) Fixieren der Position der Schablone oder des mindestens einen Schablonenteils in Bezug auf das Substrat,
4. d) Befüllen mindestens einer Ausnehmung der ein- oder mehrteiligen Schablone mit einem Dicht- und/oder Klebstoff in einem Rakelprozess sowie
5. e) Auslösen des Dicht- und/oder Klebstoffs aus der mindestens einen Ausnehmung.

A method for producing a seal and/or an adhesive structure on a substrate, in particular on a layer or sheet of an electrochemical cell, by means of stencil printing is proposed. The method comprises the following steps:

1. a) Placing the substrate on a printing table,
2. b) bringing the substrate into contact with a single-part stencil or at least one stencil part of a multi-part stencil,
3. c) fixing the position of the template or at least one template part with respect to the substrate,
4. d) filling at least one recess of the single- or multi-part stencil with a sealant and/or adhesive in a squeegee process and
5. e) releasing the sealant and/or adhesive from the at least one recess.

According to the invention, the fixing of the position of the stencil or of the at least one stencil part with respect to the substrate in step c) is effected by means of a magnetic or suction force which draws the stencil or of the at least one stencil part in the direction of the substrate.

The process enables the use of a single- or multi-part stencil that eliminates the need for webs spanning at least one recess to stabilize and/or connect the multiple stencil parts. Eliminating the webs, in turn, minimizes the risk of bubble formation during the squeegeeing process and during the release of the sealant and/or adhesive. The process thus increases process reliability and thus the quality of the printed seal and/or adhesive structure.

Particularly when using a multi-part stencil, further advantages can be achieved with the proposed method. For example, a frame-forming outer stencil part can be used, which is conventionally positioned with respect to the substrate and fixed in this position. The frame-forming outer stencil part then specifies the position for at least one additional inner stencil part, simplifying its positioning. The position of the at least one additional inner stencil part is then achieved by means of magnetic or suction force and thus independently of the frame-forming outer stencil part. This has the advantage that the separation processes for releasing the sealant and/or adhesive can be staggered in time and/or carried out at different speeds. In this way, the profile of the printed seal or adhesive structure can be specifically influenced. For example, a lip structure can be formed. This is because a higher separation speed for a given rheology of the sealant and/or adhesive produces longer threads, which in turn lead to the formation of a lip structure. The height of the lip structure can be influenced in particular by the rheology of the sealant and/or adhesive.

A further advantage of using a multi-part stencil is that the individual stencil parts are easier to clean. If cleaning is performed with a cleaning roller, the roller can be moved more quickly over the underside of each stencil part. At the same time, an improved cleaning result is achieved. Due to the improved cleaning result, the cleaning frequency can be reduced. This, in turn, enables short cycle times in the production of printed seals and/or adhesive structures. When using a multi-part stencil, individual stencil parts can also be exchanged or replaced with new or previously cleaned stencil parts, further reducing process times.

According to a preferred embodiment of the invention, the magnetic force is generated by the printing table, which is designed as a magnetic chuck or comprises a magnetic chuck. The magnetic chuck generates a magnetic field whose magnetic force attracts the stencil or at least one stencil part to the substrate, thus holding it in position.

The use of a magnetic force to fix the position of the stencil or the at least one stencil part relative to the substrate requires the stencil or the at least one stencil part to be magnetizable. The stencil or the at least one stencil part is therefore preferably made of a magnetizable material, for example, a magnetizable metal sheet.

If suction is used in step c), this is preferably also generated with the help of the printing table. This is designed as a vacuum plate or includes a vacuum plate. With the help of the vacuum plate, a vacuum is created between the substrate and the stencil or stencil part, so that the latter or this is sucked in and held in position. The substrate to be printed preferably has at least one opening through which air can be sucked in, thus creating a vacuum between the substrate and the stencil or stencil part. If the substrate to be printed is a layer or ply of an electrochemical cell, at least one media port formed in this layer or ply can be used as an opening.

The use of a vacuum plate or vacuum system has the advantage that such systems are generally lightweight and require little space. A suitably designed printing table thus exhibits low inertia, which enables rapid approach and thus bringing the substrate into contact with the stencil or at least one stencil part. Furthermore, the stencil or at least one stencil part does not necessarily have to be made of a magnetizable material, thus allowing greater material flexibility.

Bringing the substrate into contact with the stencil or the at least one stencil part in step b) is preferably effected by moving the printing table, including the substrate arranged thereon. The procedure for releasing the printing and/or adhesive in step e) can be analogous. This means that the printing table is moved to separate the substrate from the stencil or the at least one stencil part. Alternatively or additionally, the stencil or the at least one stencil part can be moved relative to the substrate.

Preferably, before the sealant and/or adhesive is released in step e), the magnetic or suction force used in step c) to fix the position of the stencil or at least one stencil part is switched off. This is because switching off the magnetic or suction force enables the separation of the substrate and the stencil or stencil part.

Furthermore, before the magnetic or suction force is switched off, the stencil or the at least one stencil part is preferably held in position by means of at least one gripper. Subsequently, with the magnetic or suction force switched off, the substrate can be separated from the stencil or the at least one stencil part in order to release the sealant and/or adhesive. When the sealant and/or adhesive is released, the at least one gripper prevents smearing due to movement of the stencil or the at least one stencil part, which could impair the quality of the printed seal and/or adhesive structure. Various gripping systems can be used, in particular mechanical, pneumatic, magnetic, and/or adhesive gripping systems.

As already mentioned, the multi-part design of the stencil enables staggered separation of the substrate and the individual stencil parts, as well as different separation speeds. According to a further preferred embodiment of the invention, when the sealant and/or adhesive is released in step e), the position of at least one stencil part relative to the substrate continues to be fixed by means of the magnetic or suction force. This means that the magnetic or suction force is not deactivated. Thus, when the sealant and/or adhesive is released, at least one stencil part initially remains on the substrate and thus in contact with the sealant and/or adhesive applied thereto by stencil printing.

Staggered separation and different separation speeds enable the targeted formation of sealing lips. As already mentioned, higher separation speeds promote thread formation and thus the formation of locally raised sealing profiles, i.e., the formation of sealing lips. The height of the sealing lip can be influenced by the rheology of the sealant and/or adhesive. The height of the sealing lip can also be influenced by the time offset. This is because the more time a sealing lip has to level out, the lower its height. Sealing lips produced earlier therefore generally have a lower height.

Alternatively or additionally, it is proposed that, after the doctor blade process in step d), a device for profiling the seal and/or adhesive structure, in particular for forming at least one sealing lip, is pressed into the seal and/or adhesive at least in part. The device can be, for example, an insert wire or a stamp. The formation of a sealing lip is particularly advantageous in those areas of the seal where leaks frequently occur, such as intersections and corners.

The squeegee process in step d) can be carried out using a standard squeegee system. Alternatively, closed squeegee head systems or rollers can be used. To reduce squeegee wear, it is proposed that at least one recess of the single- or multi-part stencil be bordered by rounded or chamfered edges. This means that sharp edges in contact with the squeegee are avoided.

Since sealant and/or adhesive residues may remain on the stencil or at least one stencil part when the sealant and/or adhesive is released from the at least one recess in the stencil, it is proposed that the stencil or at least one stencil part be cleaned after the sealant and/or adhesive has been released, for example using a cleaning roller. Since the stencil does not have any webs recessed from the underside of the stencil, cleaning is simplified with a cleaning roller. Alternatively, cleaning can be carried out in a bath, in particular an ultrasonic bath. This is particularly true if the stencil is made up of several parts, so that the parts to be cleaned are smaller. Cleaning in a bath is therefore particularly suitable for the smaller, internal stencil parts. A further advantage of using a multi-part stencil is that the parts to be cleaned can be replaced with new or previously cleaned parts, and cleaning can take place parallel to the printing process. This means that cleaning has no impact on the cycle time.

The degree of contamination of the stencil can be reduced if measures are taken to facilitate the release of the sealant and/or adhesive in step e). In a further development of the invention, it is therefore proposed that the stencil or the at least one stencil part is overmolded in regions, preferably in at least one edge region, with a material that reduces the adhesion of the sealant and/or adhesive to the stencil or to the stencil part. A polymer, for example polytetrafluoroethylene (PTFE), polypropylene (PP) and/or polyethylene (PE), is preferably used as the adhesion-reducing material. The overmolded edge region is preferably an edge that delimits the at least one recess in the stencil.

Further measures to reduce the degree of contamination and thus the cleaning effort may include adjusting the rheology of the sealant and/or adhesive and/or the process parameters. Whether corresponding measures are necessary can be determined if—according to another preferred embodiment of the invention—after the sealant and/or adhesive has been released in step e), the stencil or at least one stencil part is weighed and the weight is compared with the weight before stencil printing. In this way, process instabilities or fluctuations can be identified and the necessary adjustments can be made.

Furthermore, the stencil or the at least one stencil part preferably has a venting channel on the surface facing the substrate, which venting channel is connected to the at least one recess. The venting channel allows the air present in the recess to escape during the squeegee process in step d), so that the recess can be completely filled with the sealant and/or adhesive. The venting channel thus reduces the risk of bubble formation. To enable effective venting of the recess, the venting channel preferably has a minimum depth of 0.01 mm. In addition to being connected to the at least one recess in the stencil, the venting channel is also connected to the environment. This connection can be established, for example, via a media port, provided that the substrate to be printed is a layer or ply of an electrochemical cell.

According to a further preferred embodiment of the invention, the stencil or the at least one stencil part has a geometry on the surface facing the substrate which, in step b), is brought into contact with a surface of the substrate and/or into engagement with an oppositely designed geometry of the substrate. In this way, the stencil can be particularly easily positioned and aligned with respect to the substrate. This applies in particular if self-centering can be achieved via the geometry. Furthermore, a mechanical holding function is achieved in this way, which acts in particular in the stencil plane and prevents the stencil from slipping during the squeegee process in step d).

Furthermore, the sealant and/or adhesive is preferably applied to a monopolar or bipolar plate, a separator plate, and/or a membrane-electrode assembly of the electrochemical cell by means of stencil printing. The seal and/or adhesive structure produced from the sealant and/or adhesive then serves to separate the media within the electrochemical cell and/or seals it from the outside.

• 1 a) und b) jeweils einen Längsschnitt durch ein Substrat mit aufliegender Schablone während des Befüllens einer Ausnehmung mit einem Dicht- und/oder Klebstoff in einem Rakelprozess,
• 2 a) bis e) jeweils einen Längsschnitt durch das Substrat und die Schablone der 1 während des Auslösens des Dicht- und/oder Klebstoffs aus der Ausnehmung,
• 3 eine Draufsicht auf eine Schablone mit einer die Schablone in mehrere Schablonenteile trennenden Ausnehmung, die zur Verbindung der mehreren Schablonenteile von Stegen überspannt ist,
• 4 a) und b) erste Schritte zur Durchführung eines erfindungsgemäßen Verfahrens, wobei a) eine perspektivische Darstellung eines Drucktisches mit einem aufliegenden, zu bedruckenden Substrat und b) die Anordnung der 4a) zuzüglich zweier auf dem Substrat aufliegender Schablonenteile einer mehrteiligen Schablone zeigen,
• 5 die Anordnung der 4b) zuzüglich eines rahmenbildenden außenliegenden weiteren Schablonenteils,
• 6 a) bis f) jeweils einen vergrößerten Ausschnitt des in der 5 dargestellten Schablonenteils a) vor dem Inkontaktbringen mit dem zu bedruckendem Substrat, b) nach dem Inkontaktbringen mit dem zu bedruckenden Substrat, c) nach einem Rakelprozess zum Befüllen einer Ausnehmung der Schablone mit einem Dicht- und/oder Klebstoff, d) nach Aktivierung von Greifern, mittels welcher die innenliegenden Schablonenteile in Position gehalten werden, e) nach dem Auslösen des Dicht- und/oder Klebstoffs und f) das Substrat mit aufgedruckter Dichtung,
• 7 a) bis c) jeweils einen Querschnitt durch eine mittels Schablonendrucks hergestellten Dichtung auf einem Substrat und
• 8 eine perspektivische Darstellung eines bereichsweise umspritzten Schablonenteils einer mehrteiligen Schablone.

The invention and its advantages are explained in more detail below with reference to the accompanying drawings. These show:

• 1 a) and b) each a longitudinal section through a substrate with a stencil placed on it during the filling of a recess with a sealant and/or adhesive in a doctor blade process,
• 2 a) to e) a longitudinal section through the substrate and the template of the 1 mean during the release of the sealant and/or adhesive from the recess,
• 3 a plan view of a stencil with a recess separating the stencil into several stencil parts, which is spanned by webs to connect the several stencil parts,
• 4 a) and b) first steps for carrying out a method according to the invention, wherein a) a perspective view of a printing table with a substrate to be printed on it and b) the arrangement of the 4a) plus two stencil parts of a multi-part stencil resting on the substrate,
• 5 the arrangement of the 4b) plus an additional outer frame-forming stencil part,
• 6 a) to f) an enlarged section of the 5 shown stencil part a) before bringing into contact with the substrate to be printed, b) after bringing into contact with the substrate to be printed, c) after a squeegee process for filling a recess of the stencil with a sealant and/or adhesive, d) after activation of grippers by means of which the inner stencil parts are held in position, e) after triggering the sealant and/or adhesive and f) the substrate with printed seal,
• 7 a) to c) each show a cross-section through a seal produced by stencil printing on a substrate and
• 8 a perspective view of a partially overmolded stencil part of a multi-part stencil.

Detailed description of the drawings

Regarding the 1a), 1b), 2a) to 2e) and 3 To avoid repetition, reference is made to the introduction to the description for the explanation of the underlying problem. A preferred embodiment of a method according to the invention is described below with reference to the additional figures.

The 4a) , a printing table 10 can be seen, on which a substrate 2 to be printed is arranged. The substrate 2 to be printed can in particular be a layer or layer of an electrochemical cell, for example a monopolar or bipolar plate or a membrane electrode assembly. The representation of the substrate 2 is greatly simplified. With the aid of a method according to the invention, a seal 1 is to be produced on the substrate 2 by means of stencil printing. A multi-part stencil 3 is used, which in the present case comprises a frame-forming outer stencil part 3.1 and two further inner stencil parts 3.2, 3.3 (see 5 ). As exemplified in the 4b) As shown, the two inner stencil parts 3.2, 3.3 are first positioned on the substrate 2 such that they are arranged at a predetermined distance from one another. The two stencil parts 3.2, 3.3 are then fixed in this position. Fixing is achieved by magnetic force, with the magnetic force generated by the printing table 10, which is designed for this purpose as a magnetic clamping plate. The two stencil parts 3.2, 3.3 are also made of a magnetizable material, for example, a metal sheet. All that remains now is to bring the frame-forming outer stencil part 3.1 into contact with the substrate 2.

As in the 5 As shown, the frame-forming outer template part 3.1 has a frame 13 for stabilization and a recess 4. The recess 4 is dimensioned such that the two inner template parts 3.2, 3.3 arranged on the substrate 2 can be accommodated therein and between the template parts 3.1, 3.2, 3.3 the recess 4 remains free in the width of the seal 1 to be produced (see 6a) and 6b) After bringing the frame-forming, outer stencil part 3.1 into contact with the substrate 2, the remaining part of the recess 4 can be filled with a sealant and/or adhesive 6 in a doctor blade process. The magnetic force generated by the printing table 10 prevents the two inner stencil parts 3.2, 3.3 from slipping. This is because, unlike in the 3 As shown, the template 3 has no webs 5 for connecting its template parts 3.1, 3.2, 3.3.

The 6c ) shows the stencil 3 after the squeegee process, i.e., the recess 4 is already filled with the sealant and/or adhesive 6. In a further step, the sealant and/or adhesive 6 must now be released by separating the substrate 2 and stencil 3, for example, by lowering the printing table 10 relative to the stencil 3. To ensure the separation of the substrate 2 and the inner stencil parts 3.2, 3.3, not only is the magnetic force switched off beforehand, but a gripping system with grippers 11 is also activated, with the aid of which the stencil parts 3.2, 3.3 are held in position while the printing table 10 is lowered (see 6d )). The 6e) shows the template 3 after the sealing and/or adhesive 6 has been released. The 6f) The substrate 2 with the printed seal 1 must be removed. This may still need to cure. The curing This may require further measures, such as exposing the seal to a source of light, heat, and/or moisture. A dark reaction after exposure may also be required.

A further method according to the invention provides for the use of a printing table 10 designed as a vacuum plate. In this case, the position of the inner stencil parts 3.2, 3.3 is not fixed by magnetic force, but by suction force. This requires that a vacuum can be created via the vacuum plate not only between the printing table 10 and the substrate 2, but also between the substrate 2 and the stencil parts 3.2, 3.3. The substrate 2 must therefore have at least one opening. Since the layers or plies of an electrochemical cell generally have a plurality of openings for forming media ports, these can be used to create the vacuum, so that no further opening needs to be provided. Furthermore, the method according to the invention can be carried out using a printing table 10 designed as a vacuum plate, analogously to the method previously described with reference to the 4a) , 4b) , 5 and 6a) to 6f). The design of the printing table 10 as a vacuum plate has the advantage that, due to the lower weight of the vacuum plate compared to the magnetic clamping plate, the printing table 10 exhibits better dynamics, which has a positive effect on process times, especially in mass production.

Regardless of whether magnetic force or suction force is used to fix the position of the inner template parts 3.2, 3.3, further modifications of the method according to the invention are possible. For example, the separation of the substrate 2 from the individual template parts 3.1, 3.2, 3.3 can be staggered in time, so that individual parts, for example the inner template parts 3.2, 3.3, remain in contact with the substrate 2 and the sealant and/or adhesive 6 applied thereto for a longer period. The staggered separation enables different separation speeds and thus the formation of sealing lips 12. Corresponding sealing profiles are shown, for example, in the 7a) and 7b) shown. 7a) shows a sealing profile with two edge-side sealing lips 12 of equal height. This profile is created, for example, between the two template parts 3.2, 3.3, when the substrate 2 is delayed but simultaneously separated from the two template parts 3.2, 3.3. 7b) shows a sealing profile with two edge-side sealing lips 12 of different heights. This profile is created between two template parts 3.1, 3.2, 3.3, from which the substrate 2 is separated at different times. Height differences can be achieved - alternatively or additionally - by using different separation speeds during the separation process.

The 7c ) a further sealing profile can be seen which, in addition to the two edge sealing lips 12, has a third sealing lip 12 arranged centrally between them. In order to produce such a sealing profile, an additional device is required which is brought into contact with the sealing and/or adhesive 6 after the doctor blade process and then removed again. The device can be a wire loop or a stamp, for example. The device can consist of several individual parts and, if necessary, can only be brought into contact with the sealing and/or adhesive 6 in sections, so that the special sealing contour is only formed in certain areas of the seal 1, for example in intersection and/or corner areas which are particularly susceptible to leaks. The further sealing lip 12 in these areas helps to prevent leaks. The height of the further sealing lip 12 can in turn be adjusted via the separation time and/or the separation speed.

In order to achieve different separation times when separating the substrate 2 from the template parts 3.1, 3.2, 3.3, in a further modification of the 4a) , 4b) , 5 and 6a) to 6f), the magnetic or suction force remains activated when the sealant and/or adhesive 6 is triggered in order to keep the inner stencil parts 3.2, 3.3 in contact with the sealant and/or adhesive 6. In this case, the separation process is limited to separating the substrate 2 from the frame-forming, outer stencil part 3.1. If the substrate 2 is then to be separated from the inner stencil parts 3.2, 3.3, the gripping system is first activated and then the magnetic or suction force is switched off. The grippers 11 of the gripping system hold the stencil parts 3.2, 3.3 in position, while the printing table 10 is further lowered to separate the substrate 2.

After each printing process, the stencil parts 3.1, 3.2, 3.3 can be cleaned before being used again. This ensures that no sealant and/or adhesive residues remain on the stencil parts 3.1, 3.2, 3.3. The multi-part design of the stencil 3 has the advantage that individual stencil parts, for example the inner stencil parts 3.2, 3.3, can be kept in multiple copies and exchanged before the next printing process. The cleaning of the stencil parts 3.2, 3.3 that have already been used can then be carried out at a later time. This allows cycle times in the production of seals 1 using scrapers to be reduced. ion pressure can be shortened, which reduces costs.

The 8 A special embodiment of a template part 3.2, 3.3 of a multi-part template 3 can be seen. The template part 3.2, 3.3 is overmolded all the way around with a polymer material, so that an overmold 14 is formed, which reduces the adhesion of the sealant and/or adhesive 6 to the template part 3.2, 3.3.

The implementation of the method according to the invention is not dependent on the stencil 3 being constructed in multiple parts. This means that a single-part stencil 3 can also be used. In this case, however, the advantages achievable when using a multi-part stencil 3, such as different separation times and/or separation speeds when separating the substrate 2 from the stencil 3 or the at least one stencil part 3.1, 3.2, 3.3, are lost. When using a single-part stencil 3, the magnetic or suction force generated by the printing table 10 can be used in particular to secure the position of the stencil 3 on the substrate 2 during the squeegee process.

Claims (15)

Method for producing a seal (1) and/or adhesive structure on a substrate (2), in particular on a layer or ply of an electrochemical cell, by means of stencil printing, comprising the steps: a) placing the substrate (2) on a printing table (10), b) bringing the substrate (2) into contact with a one-part stencil (3) or at least one stencil part (3.1, 3.2, 3.3) of a multi-part stencil (3), c) fixing the position of the stencil (3) or of the at least one stencil part (3.1, 3.2, 3.3) in relation to the substrate (2), d) filling at least one recess (4) of the one-part or multi-part stencil (3) with a sealant and/or adhesive (6) in a doctor blade process and e) releasing the sealant and/or adhesive (6) from the at least one recess (4), characterized in that the fixing of the position of the stencil (3) or of the at least one stencil part (3.1, 3.2, 3.3) with respect to the substrate (2) in step c) is effected by means of a magnetic or suction force which draws the stencil (3) or the at least one stencil part (3.1, 3.2, 3.3) in the direction of the substrate (2). Procedure according to Claim 1 , characterized in that the magnetic force is generated by means of the printing table (10), which for this purpose is designed as a magnetic clamping plate or comprises a magnetic clamping plate. Procedure according to Claim 1 or 2 , characterized in that the template (3) or the at least one template part (3.1, 3.2, 3.3) is made of a magnetizable material. Procedure according to Claim 1 , characterized in that the suction force is generated by means of the printing table (10), which for this purpose is designed as a vacuum plate or comprises a vacuum plate. Method according to one of the preceding claims, characterized in that before the sealing and/or adhesive (6) is released in step e), the magnetic or suction force used in step c) to fix the position of the template (3) or of the at least one template part (3.1, 3.2, 3.3) is switched off. Procedure according to Claim 5 , characterized in that before the magnetic or suction force is switched off, the template (3) or the at least one template part (3.1, 3.2, 3.3) is held in position by means of at least one gripper (11). Method according to one of claims 1 to 4, characterized in that when the sealing and/or adhesive (6) is released in step e), the position of at least one template part (3.2, 3.3) with respect to the substrate (2) is further fixed by means of the magnetic or suction force. Method according to one of the preceding claims, characterized in that after the doctor blade process in step d), a device for profiling the seal (1) and/or adhesive structure, in particular for forming at least one sealing lip (12), is pressed at least partially into the sealant and/or adhesive (6). Method according to one of the preceding claims, characterized in that the at least one recess (4) of the single-part or multi-part template (3) is delimited by rounded or chamfered edges. Method according to one of the preceding claims, characterized in that the stencil (3) or the at least one stencil part (3.1, 3.2, 3.3) is cleaned after the release of the sealant and/or adhesive (6), for example with the aid of a cleaning roller or in a bath, in particular an ultrasonic bath. Method according to one of the preceding claims, characterized in that the template (3) or the at least one template part (3.1, 3.2, 3.3) is overmolded in regions, preferably in at least one edge region, with a material that reduces the adhesion of the sealant and/or adhesive (6) to the template (3) or to the template part (3.1, 3.2, 3.3), wherein preferably a polymer, for example polytetrafluoroethylene, polypropylene and/or polyethylene, is used as the material that reduces the adhesion. Method according to one of the preceding claims, characterized in that after the release of the sealant and/or adhesive (6) in step e), the stencil (3) or the at least one stencil part (3.1, 3.2, 3.3) is weighed and the weight is compared with the weight before the stencil printing. Method according to one of the preceding claims, characterized in that the template (3) or the at least one template part (3.1, 3.2, 3.3) has, on the surface facing the substrate (2), a ventilation channel which is connected to the at least one recess (4) and which preferably has a minimum depth of 0.01 mm. Method according to one of the preceding claims, characterized in that the template (3) or the at least one template part (3.1, 3.2, 3.3) has a geometry on the surface facing the substrate (2) which, in step b), is brought into contact with a surface of the substrate (2) and/or into engagement with an oppositely designed geometry of the substrate (2). Method according to one of the preceding claims, characterized in that the sealing and/or adhesive (6) is applied by means of stencil printing to a mono- or bipolar plate, a separator plate and/or a membrane-electrode arrangement of the electrochemical cell.