Device and method for printing substrates with sealing and / or adhesive

Abstract

The invention relates to a device for printing a substrate (1) with a sealing and / or adhesive (2), comprising a template (3) having an upper side (3.1) and an underside (3.2) and at least one recess (4) extending from the upper side (3.1) to the underside (3.2) for receiving the sealing and / or adhesive (2), at least one channel (5) connected with the notch (4) is integrated in the template (3). The invention also relates to a method for printing a substrate (1) with a sealing and / or adhesive (2) using a device according to the invention.

Description

Technical Field

[0001] The invention relates to a device and a method for printing a substrate with a seal and / or an adhesive. The substrate can be, in particular, a layer or a layer of an electrochemical cell, for example a monopolar plate, a bipolar plate, a separator plate and / or a membrane electrode assembly. Printing the substrate with a seal and / or an adhesive is used in particular to form at least one seal of an electrochemical cell. Background Art

[0002] Electrochemical cells, such as fuel cells, electrolytic cells or accumulators, have a multi-layer or multi-part structure. This structure requires a seal located in the middle in order to separate the supplied media from one another during the operation of the cell. To form the seal, a seal and / or adhesive is applied to the layers or strata of the cell. In particular, dispensing or printing methods are used here.

[0003] The large-scale production of electrochemical cells requires high processing speeds, i.e. short cycle times, as well as high process stability. Stencil printing meets these requirements in particular. The printing process in stencil printing is basically divided into the following three sub-processes:

[0004] 1. Applying the seal and / or adhesive to the template that has been previously placed on the substrate to be printed,

[0005] 2. Filling one or more template slots with sealant and / or adhesive during the coating process,

[0006] 3. The seal and / or adhesive is released from the template notches by separating the template from the substrate.

[0007] The template thickness determines the layer height of the applied structure, with the layer height usually being in the range of 300 μm to 500 μm. However, for seals of electrochemical cells, layer heights of up to 1500 μm are required in order to compensate for tolerances and to be as free as possible in the design of the structure to be applied. This is because, depending on the respective sealing concept, the structure to be applied can be large and / or complex.

[0008] Therefore, in order to achieve the required layer height for the seals for electrochemical cells during stencil printing, thicker stencils must be used. However, this increases the risk of bubbles being introduced during the doctor blade process in order to fill the stencil slots with the applied seal and / or adhesive, which subsequently lead to defects. This is because as the thickness of the stencil increases, the volume of the stencil slots to be filled with the seal and / or adhesive also increases.

[0009] The problem is based on the following Figure 1a )and Figure 1b), which shows a template 3 with a slot 4 placed on a substrate 1, which needs to be filled with a sealant and / or adhesive 2. To this end, a scraper 12 is scraped on the upper side 3.1 of the template 3. The end facing the slot 4 cannot squeeze out all the air from the slot 4, so that bubbles 13 are formed in the slot 4, which prevent the slot 4 from being completely filled. In this case, the printed pattern has gaps or defects. The risk of containing bubbles 13 increases with the thickness d of the template 3. Summary of the invention

[0010] The object of the present invention is to reduce the risk of bubbles and thus defects when printing substrates with sealants and / or adhesives.

[0011] To achieve this object, a device is proposed having the features of claim 1 and a method having the features of claim 9. Advantageous developments of the invention can be gathered from the dependent claims.

[0012] The proposed device for printing a substrate with a seal and / or adhesive comprises a template having an upper side and a lower side and at least one notch extending from the upper side to the lower side for receiving the seal and / or adhesive. At least one channel connected to the notch is integrated in the template.

[0013] At least one channel integrated into the template enables venting of the slot when filling with a seal and / or adhesive, so that the risk of air bubbles being trapped in the slot is reduced. Venting via the channel thus helps to avoid defects in the printed pattern, which is particularly meaningful when the printing process is used to form a seal.

[0014] Since the risk of bubble formation is minimized, the template thickness can be increased, so that layer heights significantly exceeding 300 μm, for example 1500 μm, as required for seals of electrochemical cells, can be achieved.

[0015] The location, shape and / or size of the at least one channel may depend on a variety of factors.

[0016] The position is primarily predetermined by the scraper direction, i.e. the scraping direction of the scraper, and by the shape of the structure to be applied, in particular the sealing structure. For example, the structure can be a closed shape with end and / or corner areas that are difficult to fill. At least one channel is preferably arranged in such an end and / or corner area, specifically in a manner that is located next to and / or behind the slot in the scraper direction. Ideally, the channel is adjacent to the area of ​​the slot that is filled with a seal and / or adhesive last. If the channel is large enough so that the channel itself can be filled with a seal and / or adhesive, the channel is preferably arranged to be filled with a seal and / or adhesive last. In this case, the channel serves as a kind of overflow, which first receives the air squeezed out of the slot and then receives excess seal and / or adhesive.

[0017] The shape and / or size of the passage are ideally matched to the rheological properties, in particular the viscosity of the seal and / or adhesive. In addition, it is decisive for the shape and / or size of the passage whether the passage is only used for exhaust or should also have an overflow function.

[0018] The number of channels can also vary and depends in particular on the complexity of the structure to be printed. Because the more complex the structure, the more complex the shape of the at least one notch in the template, so that the template may be difficult to vent in several areas. A channel can be arranged in each of these areas. When arranging the channels, it is necessary to pay attention to the direction of the scraper.

[0019] The scraper direction does not have to be predetermined, but can also be generated by the position of the at least one channel. This results in greater freedom in the arrangement of the at least one channel. When printing the substrate, the scraper direction can be selected so that when the scraper is scraped, the groove in the area of ​​the channel is finally filled with sealing and / or adhesive.

[0020] According to a preferred embodiment of the invention, at least one channel extends from the upper side of the template to the lower side and is enlarged in the region of the notch, preferably in the end and / or corner region of the notch. Since the channel is guided from the upper side to the lower side similar to the notch, it can be formed in the template together with the notch in one working step, for example by cutting or punching. In this case, the template can be manufactured simply and cost-effectively. The enlargement of the notch by the channel can be used not only for venting, but also, if necessary, for accommodating excess sealing and / or adhesive, so that the channel forms a kind of overflow.

[0021] In order to expand the notch of the template, the channel can be configured as a projection of the notch. When the channel is arranged in the end and / or corner region of the notch, the projection can extend the notch beyond the end and / or corner region. In this case, the extension is preferably carried out in the scraper direction.

[0022] According to a preferred embodiment of the invention, at least one channel extends from the upper side of the template to the limiting wall of the slot. That is, the channel opens into the slot or extends from the slot to the upper side of the template. For this purpose, the channel has an inclined or angled trend at least in sections. The inclined trend can be realized relatively easily, for example by a simple inclined hole. In the case of an angled trend, the channel preferably consists of a plurality of sections, wherein at least one section can also be implemented as a hole. The hole can then be guided vertically through the template.

[0023] Since the bore can be realized relatively simply and cost-effectively, it is further proposed that at least one channel is embodied at least in sections as a bore formed in the template.

[0024] If at least one channel consists of a plurality of sections, these sections can have different cross sections. That is, the cross section of at least one channel can vary over its entire length. This is particularly advantageous if the channel has an angled course or consists of at least two sections oriented at an angle to one another.

[0025] According to a preferred embodiment of the invention, at least one step extending to the notch is introduced, in particular milled, on the underside of the template, from which at least one channel, preferably as a hole, extends to the upper side of the template. Due to the at least one step, the channel or hole can be guided vertically through the template, since the necessary connection of the channel to the notch to be vented can be produced by a further channel section extending transversely to the channel or hole, which is delimited by the step of the template extending to the notch.

[0026] As an extended measure, it is proposed to introduce, in particular mill, at least one further step extending to the notch on the underside of the template, wherein in the region of the further step a sheet is inserted, preferably welded or bonded into the template, which sheet together with the first step at least partially delimits the channel. Since the sheet is inserted only in the region of the further step, a cavity remains between the sheet and the first step, which cavity is open toward the notch but is closed by the sheet toward the underside of the template. The connection of the channel to the notch is produced by this cavity, or the cavity itself forms a section of the channel.

[0027] The sheet inserted into the template can be made of metal or plastic, for example. By welding or bonding of the sheet, even after multiple printing and cleaning cycles, the sheet also remains reliably in the template.

[0028] Advantageously, the sheet ends flush with the underside of the template. This also ensures that the template is in surface contact with the substrate during printing. In addition, it is prevented that the seal and / or adhesive gets under the template during printing and the printed structure acquires unclear contours.

[0029] The template of the device according to the invention can have one or more channels for venting at least one slot. If the template has more than one channel, these channels can be designed identically or differently. That is, the different embodiments of the channels described above can be implemented in different combinations in one template. For example, the template can have at least one channel leading from the upper side to the lower side and at least one further channel leading from the limiting wall of the slot to the upper side of the template.

[0030] As a further development of the invention, it is proposed that the device has a scraper for scraping the seal and / or adhesive on the upper side of the template. During scraping, at least one notch of the template is filled with the seal and / or adhesive by means of the scraper. The scraper is preferably wider than the at least one notch, so that the notch can be filled with the seal and / or adhesive in just one scraping process.

[0031] Furthermore, a method for printing a substrate with a seal and / or adhesive using the device according to the invention is proposed. The method comprises the following steps:

[0032] - placing the template on the substrate so that the underside of the template is in contact with the substrate surface,

[0033] - applying a sealant and / or adhesive to the upper side of the formwork,

[0034] At least one slot of the template is filled with a sealant and / or adhesive by means of a scraper which scrapes on the top side of the template in the direction of the at least one channel, wherein air present in the slot is forced out of the slot through the at least one channel.

[0035] The position of the at least one channel determines the scraper direction, i.e. the direction of movement of the scraper. The direction of movement is selected such that the air present in the slot is displaced in the direction of the at least one channel by the seal and / or adhesive pressed into the slot during scraping by the scraper. Thus, the remaining air can escape through the at least one channel, so that the slot is completely filled with the seal and / or adhesive. In this way, air bubbles and thus defects in the printed structure can be avoided.

[0036] Preferably, when filling at least one notch of the template with sealing and / or adhesive, the area of ​​the notch adjacent to the channel or the channel itself is filled last. The channel thus remains open until the end in order to ensure the necessary venting of the notch. If the channel itself can also receive sealing and / or adhesive due to its shape and / or size, the channel simultaneously forms a kind of overflow for excess sealing and / or adhesive. However, unlike the notch, the channel does not have to be completely filled with sealing and / or adhesive, since it is not part of the structure that is actually applied.

[0037] The scraper is preferably placed at the end of the template furthest from the at least one channel for venting the notch. The scraper then scrapes over the notch first and over the channel last when scraping. This does not exclude the presence of additional channels for venting the notch which are not located behind the notch in the scraper direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. These drawings show:

[0039] Figure 1a) and 1b) In each case a longitudinal section of a conventional device for printing a substrate is shown during scraping with a doctor blade.

[0040] Figure 2a) shows a bottom view of a first device according to the invention for printing a substrate with a seal and / or adhesive; Figure 2b ) shows a longitudinal section of the device.

[0041] Figure 3a ) shows a bottom view of a second device according to the invention for printing a substrate with a seal and / or adhesive; Figure 3b ) shows a longitudinal section of the device.

[0042] Figures 4a) to 4h) The three dimensional views of the templates of the third device according to the invention are respectively shown during their gradual introduction into the channel.

[0043] Figure 5 : A top view of a fourth template of a device according to the present invention.

[0044] Figure 6 : With the help of Figure 5 Figure 2. Top view of a template-fabricated substrate with printed structures.

[0045] Figure 7 : Top view of a substrate with printed structures produced with the aid of a modified template.

[0046] Figure 8 : Figure 6 or Figure 7 Enlarged detail in the corner area of ​​the seal. DETAILED DESCRIPTION

[0047] At the beginning of the manual, Figure 1a )and Figure 1b ) describes the problem of bubble formation during stencil printing, so Figure 1a )and Figure 1b ) Refer to the beginning of the manual.

[0048] According to Figure 2 to Figure 8 Preferred embodiments of the device according to the invention for printing a substrate with a seal and / or adhesive are described in more detail.

[0049] The substrate 1 can be in particular a layer or a sublayer of an electrochemical cell, for example a bipolar plate or a membrane electrode assembly. By printing the substrate 1 with the sealing and / or adhesive 2, in particular a seal 17 of an electrochemical cell can be formed.

[0050] Figure 2a )and Figure 2b) shows a first preferred embodiment of a device for printing a substrate 1 with a sealant and / or adhesive 2. The device comprises a template 3 and a scraper 12. To print the substrate 1, the template 3 is first placed so that the lower side 3.2 of the template 3 is in surface contact with the substrate 1. The sealant and / or adhesive 2 is then applied to the upper side 3.1 of the template 3 and scraped with the help of the scraper 12. The scraper 12 pushes the sealant and / or adhesive 2 into at least one notch 4 formed in the template 3. Since the notch 4 extends from the upper side 3.1 of the template 3 to the lower side 3.2, the thickness d of the template 3 determines the layer thickness of the applied sealant and / or adhesive 2 and thus the height of the subsequent structure or seal 17.

[0051] The greater the thickness d of the template 3, the greater the risk of bubbles forming during scraping (see Figure 1b ).exist Figure 2a )and Figure 2b ) has a channel 5 connected to the slot 4 to avoid air bubbles 13, which is used to vent the slot 4 when scraping with a scraper 12. For this purpose, the channel 5 is arranged behind the slot 4 in the scraper direction 14 (see arrow). In the present case, the channel 5 is designed as an obliquely extending hole 8, which extends from the limiting wall 7 of the slot 4 to the upper side 3.1 of the template 3. The diameter of the channel 5 is set large enough so that air can flow through it without hindrance.

[0052] exist Figure 3a )and Figure 3b ) shows another preferred embodiment of the device according to the invention. The device also comprises a template 3 and a slot 4 formed in the template 3, the template having an upper side 3.1 and a lower side 3.2, the slot extending from the upper side 3.1 to the lower side 3.2 of the template 3. In order to vent the slot 4, a channel 5 is formed in the template 3 behind the slot 4 in the scraper direction 14, which channel does not extend obliquely but at an angle. Therefore, the channel 5 has a plurality of sections, which are introduced in a plurality of working steps when manufacturing the template 3. These working steps are in Figure 4a) to Figure 4h) It is shown as an example in FIG.

[0053] Figure 4a ) shows a bottom view of a template 3 with a notch 4 but without a channel 5. In order to form the channel 5, a step 10 is first introduced on the underside 3.2 of the template 3, which extends to the notch 4 (see Figure 4b Another step 9 is formed within the step 10 (see Figure 4c ), which also extends to the notch 4 so that it is surrounded on three sides by the step 10. The step 9 is designed to be rounded at its end facing away from the notch 4. A hole 8 is then introduced in the region of the rounded end (see Figure 4d), which extends from the step 9 to the upper side 3.1 of the template 3. In order to close the channel 5 on the substrate side, a sheet 11 is inserted, preferably welded or bonded into the template 3 (see Figure 4e ), specifically in such a way that the sheet 11 ends flush with the underside 3.2 of the template 3 (see Figure 4f Since both steps 9, 10 extend to the notch 4, the channel 5 projects at one end into the limiting wall 7 (see Figure 4g ), and at the other end projects out from the upper side 3.1 of the template 3 (see Figure 4h ).

[0054] from Figure 5 Another preferred embodiment of the device according to the invention can be seen. Only a top view of the template 3 of the device is shown. The template 3 has a notch 4 for forming a surrounding seal 17 on the bipolar plate (see Figure 6 ), so that the bipolar plate constitutes the substrate 1 to be printed. Figure 6 The bipolar plate shown in FIG. 1 has a plurality of ports 16 for guiding different media through. Seals 17 are used for media separation.

[0055] Since the seal 17 is circumferential, the notch 4 divides the template 3 into an inner part and an outer part, which are connected by a web 15 (see Figure 5 ). The thickness of the web 15 is less than the thickness d of the template 3 , so that in the region of the web 15 the substrate 1 can also be printed with the seal and / or adhesive 2 .

[0056] exist Figure 5 The template 3 shown in the figure has a channel 5 in the end and / or corner area 6 of the slot 4, which expands or prolongs the slot 4 in the scraper direction 14. The channel 5 extends from the upper side 3.1 of the template 3 to the lower side 3.2, just like the slot 4. When scraping the seal and / or adhesive 2 with the help of the scraper 12, the scraper finally scrapes through the channel 5, so that the air present in the slot 4 is completely removed and the slot 4 is completely filled with the seal and / or adhesive 2. Excess seal and / or adhesive 2 is scraped into the channel 5, so that the channel 5 can also be completely or partially filled with seal and / or adhesive 2. Therefore, the seal 17 produced in this way can have a protrusion 18, which is formed by the excess seal and / or adhesive 2 (see Figure 6 and Figure 8 ). The protrusion 18 does not have a sealing function. In addition, the sealing function of the sealing member 17 is not affected by the protrusion 18.

[0057] exist Figure 7, a modified seal 17 is shown. Here, the seal has a total of three projections 18, because a template 3 with a plurality of channels 5 (not shown) is used to produce the seal 17. The position of the projections 18 corresponds to the position of the channels 5 for exhaust. Therefore, a second channel 5 is provided in the other corner and / or end region 6 of the slot 4. The third channel 5 is arranged laterally in the slot 4, so that the third projection 18 is located laterally. If the scraper 12 scrapes across the template 3 when scraping from right to left, air can also escape from the slot 4 through the channels 5 arranged laterally.

Claims

1. A device for printing a substrate (1) with a sealant and / or adhesive (2), the device comprising a template (3), the template having an upper side (3.1) and a lower side (3.2) and at least one notch (4) extending from the upper side (3.1) to the lower side (3.2), the notch being used to receive the sealant and / or adhesive (2), wherein: At least one channel (5) connected to the slot (4) is integrated into the template (3).

2. The device according to claim 1, It is characterized in that The at least one channel (5) extends from the upper side (3.1) to the lower side (3.2) of the template (3), and the slot (4) widens regionally, preferably in the end and / or corner regions (6) of the slot (4).

3. The device according to claim 1 or 2, It is characterized in that The at least one channel (5) extends from the upper side (3.1) of the template (3) to the delimiting wall (7) of the groove (4) and has an inclined or angled course at least in sections.

4. The device according to any one of the preceding claims, It is characterized in that The at least one channel (5) is embodied at least in sections as a hole (8) formed in the template (3).

5. The device according to any one of the preceding claims, It is characterized in that At least one step (9) extending to the groove (4) is introduced, in particular milled, on the underside (3.2) of the template (3), and the at least one channel (5), preferably as a hole (8), extends from the step to the upper side (3.1) of the template (3).

6. The device according to claim 5, It is characterized in that At least one further step (10) extending to the groove (4) is introduced, in particular milled, on the underside (3.2) of the template (3), wherein in the region of the further step (10) a sheet (11) is inserted, preferably welded or adhesively bonded, into the template (3), which sheet together with the first step (9) at least partially delimits the channel (5).

7. The device according to claim 6, It is characterized in that The sheet (11) ends flush with the underside (3.2) of the template (3).

8. The device according to any one of the preceding claims, It is characterized in that The device has a scraper (12) for scraping the seal and / or adhesive (2) on the upper side (3.1) of the template (3).

9. A method for printing a substrate (1) with a sealant and / or adhesive (2) using a device according to any one of the preceding claims, comprising the following steps: - placing the template (3) onto the substrate (1) so that the lower side (3.2) of the template (3) is in surface contact with the substrate (1), - applying the seal and / or adhesive (2) to the upper side (3.1) of the formwork (3), - filling at least one slot (4) of the template (3) with the sealant and / or adhesive (2) with the aid of a scraper (12), which scrapes on the upper side (3.1) of the template (3) in the direction of the at least one channel (5), wherein the air present in the slot (4) is squeezed out of the slot (4) through the at least one channel (5).

10. The method according to claim 9, It is characterized in that When filling the at least one recess (4) of the template (3) with the sealant and / or adhesive (2), the region (13) of the recess (4) directly adjacent to the channel (5) or the channel (5) itself is filled last.

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