Method for simultaneously applying at least two polymer functional materials to a substrate

Abstract

The invention relates to a method for simultaneously applying at least two polymer materials (12, 14) to a substrate (10), which either remains in a stationary position (16) or moves in a feed direction (66). The following method steps are carried out: A first polymer functional material (12) is applied by means of at least one application element (22, 26, 60, 62) to at least first application surfaces (28, 30) of the substrate. The second polymer functional material (14) is then applied by means of at least one application element (24, 60, 62) to a third application surface (32) which is enclosed by or adjoins the at least two application surfaces (28, 30). The invention also relates to the use of the method for applying at least two polymer functional materials (12, 14) to monopolar or bipolar plates by screen or stencil printing.

Description

[0001] Description

[0002] title

[0003] Method for the simultaneous application of at least two polymer functional materials to a substrate

[0004] Technical area

[0005] The invention relates to a method for the simultaneous application of at least two polymer functional materials to a substrate that either remains in a stationary position or moves in a feed direction. Furthermore, the invention relates to the use of the method for applying at least two polymer functional materials by screen or stencil printing to monopolar or bipolar plates, as well as to the use of at least two polymer functional materials by application rollers to monopolar or bipolar plates.

[0006] State of the art

[0007] To achieve sufficient electrical efficiency in fuel cells, which are becoming increasingly important in the context of electromobility, individual fuel cells are stacked on top of one another. The resulting stack is also referred to as a stack. Following common manufacturing processes, an adhesive seal is screen-printed onto a bipolar plate to construct the stack. A coating material is applied to the flow field of the active side of the bipolar plate, for example, using a rolling process. The disadvantages of these processes are that the application of two functional polymer materials to a substrate is carried out using two processes: screen printing and rolling, which requires at least two process steps. If curing processes for two materials must be taken into account, additional process steps are required.The application of two functional polymer materials to a substrate using the above process requires a long cycle time, so rapid production of a stack or stack is generally not possible. High production costs arise because two additional processes must be used.

[0008] The following disadvantages can also arise with standard screen or stencil printing: The print quality of the material printed using screen or stencil printing depends on numerous influencing factors, such as the printing speed (forward and backward speed), the separation speed, the rheological properties of the material being applied, the properties of the filler material with regard to particle size and particle distribution, the squeegee material, the squeegee angle, the stencil material, and the stencil grid structures, to name just a few. As soon as one of the parameters listed as examples varies, the print quality can be significantly affected. This, however, leads to significant fluctuations in production quality. Overall, this process can be classified as unstable.

[0009] It should also be emphasized that standard screen and / or stencil printing typically only allows one material to be printed on a substrate. It is not possible to apply two materials to a substrate simultaneously.

[0010] Disclosure of the invention

[0011] Following the solution according to the invention, a method is proposed for the simultaneous application of at least two polymer functional materials to a substrate, which either remains in a stationary position or moves in a feed direction, wherein at least the following method steps are carried out: a) applying the first polymer functional material by means of at least one application element to at least first application surfaces of the substrate, b) applying the second polymer functional material by means of at least one further application element to a central application surface enclosed by or adjacent to the at least first application surfaces. The solution proposed according to the invention thus allows two polymer functional materials to be applied simultaneously, which significantly shortens the required cycle times.

[0012] In an advantageous development of the method proposed according to the invention, an adhesive sealant is applied as the first polymer functional material according to method step a).

[0013] In a further advantageous development of the method proposed according to the invention, an electrically conductive adhesive is applied as a second polymer functional material according to method step b).

[0014] Finally, in a further advantageous embodiment of the method proposed according to the invention, according to method step a), first application surfaces are traversed by a first and third application element in a first or a second feed direction.

[0015] Furthermore, following the method proposed according to the invention, a third application surface is passed over by a second application element according to method step b).

[0016] In the method proposed by the invention, all application elements move above a screen or stencil. According to a second aspect of the method proposed by the invention, process steps a) and b) are carried out by a first application roller on a first active side of the substrate.

[0017] Further following the method proposed according to the invention, the method steps a) and b) are carried out by a first and a second application roller on a first side and a second side of the substrate.

[0018] In an advantageous development of the method proposed according to the invention, the first polymer functional material and the second polymer functional material are removed from a material container in which the first polymer functional material and the second polymer functional material are separated from each other by a spatial separation. This ensures that different areas of the roller shells of the first and second application rollers are wetted with only one of the first and second polymer functional materials each.

[0019] In the method proposed according to the invention, the first polymer functional material and the second polymer functional material are further removed from the material container, in which the first polymer functional material and the second polymer functional material are separated from each other by a spatial separation.

[0020] In a further advantageous embodiment of the method proposed according to the invention, the first polymer functional material and the second polymer functional material are each conveyed to the first application roller and / or the second application roller by means of an intermediate roller. This allows a uniform application thickness to be achieved due to splitting processes in the roller gaps between the intermediate roller and the respective first and second application rollers.

[0021] Advantageously, the method proposed according to the invention can be used to apply a first adhesive contour or a second adhesive contour to the first side of the substrate, in particular in the case of the coating for producing a multipolar plate.

[0022] Furthermore, as an alternative to the preceding procedure, in the method proposed according to the invention, a first adhesive contour and / or a second adhesive contour can be applied to the first active side and the second active side of the substrate in the case of producing a bipolar plate.

[0023] In the case of the production of a monopolar plate, said first adhesive contour or said second adhesive contour can be produced on the first active side of the substrate, in which case a cooling side is created on the back of the active side of the substrate.

[0024] Furthermore, the invention relates to the use of the above-described method for applying at least two polymer functional materials by screen or stencil printing to produce monopolar or bipolar plates. Furthermore, the method proposed according to the invention can be used to produce monopolar or bipolar plates, wherein the at least two polymer functional materials are applied to the substrate via application rollers.

[0025] Advantages of the invention

[0026] According to a first aspect of the present invention, the method proposed according to the invention enables the simultaneous application of two polymer functional materials to different locations on a substrate by screen and stencil printing using at least two doctor blade-shaped application elements, which considerably shortens the cycle times for production or coating of the substrate. In particular, different layer thicknesses of the two polymer functional materials to be applied by screen and stencil printing can be achieved by adjusting the stencil thickness.

[0027] By means of screen and stencil printing, adhesive sealing material can be applied to the edge of the active side of a monopolar plate, for example, to seal the monopolar plate. By applying the electrically conductive adhesive to the webs of the flow field, fixing, bonding or electrical contacting of gas diffusion layers on the MEA can be achieved.

[0028] According to the second aspect of the solution proposed by the invention, a rolling process can be used to rapidly apply the coating to relatively large application areas on the substrate, whether on a first active side or a second active side, by using said first and second application rollers with an intermediate roller interposed. A very rapid and simultaneous application of two different substances—in this case, the first polymer functional material and the polymer functional material—to different zones of the substrate simultaneously on both sides can be achieved. This allows, for example, significant cycle time reductions for the assembly of stacks in the case of the production of monopolar plates and bipolar plates for fuel cell stacks.Only one process and one process step are used instead of several processes and multiple process steps, resulting in an overall reduction in production costs and an increase in cycle times. Compared to screen and stencil printing, the use of application rollers is characterized by the fact that the application via rotating roller shells depends on relatively few process parameters, thus achieving a stable application process.

[0029] The method proposed by the invention enables continuous stack production without interrupted production steps, thus enabling high-volume production. Furthermore, the method proposed by the invention enables a significant reduction in production costs, as only one system is required for two processes. Furthermore, very high product quality and reproducibility can be achieved, while the scrap rate can be drastically reduced.

[0030] Short description of the drawings

[0031] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0032] They show:

[0033] Figure 1 shows a simultaneous application of two polymer functional materials to different locations of a substrate, in particular a bipolar plate, by two doctor blade-shaped application elements in screen and stencil printing

[0034] Figure 2 shows the simultaneous application of two polymer functional materials to different areas of a substrate by three doctor blade-shaped application elements using screen and stencil printing,

[0035] Figures 3.1 , 3.2 different design variants of roller structures of application rollers,

[0036] Figure 4 shows a side view of application units having application rollers for applying polymer functional materials to an active and a cooling side of a substrate, Figure 5 shows a variant of application units with application rollers for applying polymer functional materials to two active sides,

[0037] Figure 6 is a side view of the application units according to Figure 5,

[0038] Figures 7.1 , 7.2 Adhesive contours that are applied, for example, to a monopolar plate and a bipolar plate and

[0039] Figures 8.1 , 8.2 Top views of the material vessel in which the first and the second polymer functional material are stored spatially separated from each other.

[0040] Embodiments of the invention

[0041] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0042] Figure 1 shows a simultaneous application of two polymer functional materials to different locations of a substrate, in particular a bipolar plate, by two doctor blade-shaped application elements in screen and stencil printing according to a first aspect of the present invention.

[0043] Figure 1 shows that a substrate 10, which is, for example, a base material for a bipolar plate or a monopolar plate to be produced, is covered on its first side 18 by a screen or a stencil 44. The screen or stencil 44 comprises different application areas. As shown in Figure 1, the substrate 10 is in a stationary position 16. The first side 18 of the substrate 10 is covered by said screen or stencil 44. This comprises at least two parts, wherein a first part lies above a flow field 42, in particular a monopolar plate or a bipolar plate as substrate 10, and a further part extends around it and defines transverse and longitudinal edge regions.According to the illustration in Figure 1, a first polymer functional material 12 is applied by a first doctor blade-shaped application element 22, for example, in a first feed direction 36. This can be done in an analogous manner at the opposite edge of the screen or stencil 44.

[0044] With respect to the screen 44 or the template 44, first application surfaces 28 run in the transverse direction and second application surfaces 30 run in the longitudinal direction with respect to a third application surface 32 defined by the flow field 42, which runs essentially centrally.

[0045] Figures 1 and 2 show that the simultaneous application of both polymer functional materials 12, 14 to different application surfaces 28, 30, 32 can be carried out both according to Figure 1 with a first doctor blade-shaped application element 22 and a second doctor blade-shaped application element 24 above the flow field 42, and according to Figure 2, a simultaneous application of the two polymer functional materials 12, 14 to different application surfaces 28, 30, 32 can be carried out with three doctor blade-shaped application elements 22, 24, 26. In the case of the embodiments of the method proposed according to the invention shown in Figures 1 and 2, different layer thicknesses of the two polymer functional materials 12, 14 used can be set by adjusting the respective areas on the screen 44 or the stencil 44.

[0046] According to the embodiment shown in Figure 1, the two doctor blade-shaped application elements 22, 24 can be moved simultaneously along their own designated path without disruption by means of a corresponding control system. This also applies to the second doctor blade-shaped application element 24.

[0047] The two polymer functional materials 12, 14 applied via the doctor-shaped application elements 22, 24, 26 according to Figures 1 and 2 can be an adhesive sealing material in the case of the first polymer functional material 12 and an electrically conductive adhesive in the case of the second polymer functional material 14. This adhesive is applied in particular above the flow field 42 of the substrate 10, for example, a bipolar plate, by means of the second application element 24. A second aspect of the solution proposed according to the invention is examined in more detail in Figures 3.1 and 3.2.

[0048] The illustrations in Figures 3.1 and 3.2 show differently structured roller shells 58 of application rollers 60, 62 (not shown in detail here) (see illustration in Figure 4). According to the variant shown in Figure 3.1, the third application surface 32 runs along the shell surface 58 of the roller structure shown there. This surface is bordered at the edges by both application surfaces 30.

[0049] Figure 3.2 shows a modification of the roller structure according to Figure 3.1 such that, in this embodiment of the roller structure of the roller shell 58, the substantially centrally extending application surface 32 is delimited at both edges by second application surfaces 30. In the embodiment shown in Figure 3.2, the centrally extending third application surface 32 is interrupted at a first application surface 28, which extends transversely on the roller shell 58.

[0050] With the roller shells 58 configured in Figures 3.1 and 3.2, according to the embodiment variant in Figure 3.1, two sides, ie the two application surfaces 30 in the longitudinal direction can be coated with a first polymer functional material 12, preferably an adhesive sealant, and the third application surface 32, which extends continuously in the middle, can be coated with a second polymer functional material 14, a conductive adhesive.

[0051] In the embodiment according to Figure 3.2, the third application surface 32 can be coated all around the edge with the first polymer functional material 12, in particular an adhesive sealant, and within the centrally running third application surface 32 with the second polymer functional material 14 in the form of a conductive adhesive, which, however, in contrast to the embodiment according to Figure 3.1, does not run continuously.

[0052] Figure 4 shows a side view of a schematically illustrated application unit.

[0053] In contrast to the first aspect of the present invention, according to which the substrate 10 remains in the stationary position 16, the substrate 10 is conveyed in a feed direction 66. In the variant according to Figure 4, for example, a monopolar plate is produced from the substrate 10, which has a first active side 52 and a cooling side 56. The cooling side 56 and the first active side 52 of the substrate 10 are coated continuously or discontinuously by a first applicator roller 60 and a second applicator roller 62, respectively. The roller shells 58 of the first applicator roller 60 and the second applicator roller 62 can have roller structures according to Figures 3.1 and 3.2. Each of the two applicator rollers 60, 62 is in linear contact with an intermediate roller 64. The intermediate roller 64, in turn, dips at an immersion or conveying side 78 into a material container 72, which is designed, for example, in the shape of a trough 76.The first polymer functional material 12 and the second polymer functional material 14 are located in the trough-shaped material container 72, separated from each other by a spatial separation 74. The first polymer functional material 12 is preferably an adhesive sealant, and the second polymer functional material 14 is preferably an electrically conductive adhesive. Due to the spatial separation 74 within the material container 72, said polymer functional materials 12, 14 do not mix with each other, but rather remain separate from each other.

[0054] The intermediate roller 64, which dips into the material container 72 at the dipping side 78, transfers the first polymer functional material 12 and the second polymer functional material 14 in film form to the roller shells 58 structured according to Figures 3.1 and 3.2. Due to the partial wetting of the roller shells 58, said polymer functional materials 12, 14 can be transferred to the first active side 52 of the substrate 10 conveyed in the feed direction 66.

[0055] In the case of producing a monopolar plate from the substrate 10, the cooling side 56 remains uncoated, while the first active side 52 is coated with the first polymer functional material 12 or the second polymer functional material 14 according to the roller structure according to Figures 3.1 and 3.2.

[0056] Figure 5 shows that, in the case of producing a bipolar plate from the substrate 10 conveyed in the feed direction 66, both the first active side 52 and the second active side 54 are coated via the first application roller 60 and the second application roller 62. In this case, the first polymer functional material 12 and the second polymer functional material 14 are applied to the first active side 52 and the second active side 54 of the substrate 10 on both the front and back sides of the substrate 10 conveyed in the feed direction 66, in accordance with the roller structures of the roller shell 58, as shown in Figures 3.1 and 3.2. Analogous to the illustration in Figure 4, the first polymer functional material 12 and the second polymer functional material 14 are separated from one another in the material container 72 by a spatial separation 74, so that mixing of said polymer functional materials 12, 14 is prevented.

[0057] Analogous to the illustration in Figure 4, for example, the intermediate rollers 64, which dip into the material containers 72 on the dipping or conveying side 78, can rotate in a first direction of rotation 68, corresponding to a clockwise direction, or in a second direction of rotation 70, corresponding to a counterclockwise direction. The same applies to the first and second application rollers 60, 62, which can rotate in both the first direction of rotation 68 (clockwise) and the second direction of rotation 70 (counterclockwise).

[0058] Figure 6 shows a side view of the application units shown schematically in Figures 4 and 5.

[0059] From the illustration in Figure 6, it can be seen that the substrate 10 is coated in its edge regions with the said first polymer functional material 12 and in its central region with the second polymer functional material 14. Due to the spatial separation 74 of the polymer functional materials 12, 14 in the material container 72 and the correspondingly structured roller shells 58 of the intermediate roller 64, for example, the second application roller 62 according to Figure 6, the said coating pattern is created on the substrate 10, which is conveyed in the feed direction 66.

[0060] Figures 7.1 and 7.2 show different adhesive contours 80, 82.

[0061] While the first adhesive contour 80 shown in Figure 7.1 is coated in the edge regions opposite one another with the first polymer functional material 12, preferably an adhesive sealant, the central region lying between these within the first adhesive contour 80 is provided in strip form with the second polymer functional material 14, an electrically conductive adhesive.

[0062] The first adhesive contour 80 shown in Figure 7.1 is manufactured, for example, with a roller structure as can be seen in Figure 3.1, ie with a continuous third application surface 32 which runs centrally and lies between the second application surfaces 30 shown in Figure 3.1, which extend in the longitudinal direction.

[0063] In contrast, Figure 7.2 shows the second adhesive contour 82, which, in contrast to the first adhesive contour 80 shown in Figure 7.1, has a central region surrounded on all sides by regions with the first polymer functional material 12 in the form of an adhesive sealant, and which is manufactured using the roller structure according to Figure 3.2. In this roller structure according to Figure 3.2, the roller shell 58 is constructed such that the central region 32 does not extend continuously, but is interrupted by the first transverse application surfaces 28.

[0064] Figures 8.1 and 8.2 show schematically a plan view of the upper side, ie the immersion or conveying side 78 of the material containers 72 formed in trough shape 76. This shows spatial separations 74 in each case, so that in the material containers 72 the first polymer functional material remains separated from the second polymer functional material 14.

[0065] Figure 8.2 also shows that the material container 72, which is designed in the form of a trough 76, has a width 84 which is smaller than its length 86.

[0066] The invention further relates to the use of the method for applying at least two polymer functional materials 12, 14 by screen or stencil printing using a screen 44 or a stencil 44 for producing monopolar or bipolar plates from a substrate 10 in a stationary position 16. Furthermore, the invention relates to the use of the method for applying at least two polymer functional materials 12, 14 for producing monopolar or bipolar plates from a substrate 10 transported in the feed direction 66. The invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, a large number of modifications are possible within the scope specified by the claims, which are within the scope of expert action.

Claims

Claims 1 . Method for the simultaneous application of at least two polymer functional materials (12, 14) to a substrate (10), which either remains in a stationary position (16) or moves in a feed direction (66), with at least the following method steps: a) applying the first polymer functional material (12) by means of at least one application element (22, 26, 60, 62) to at least first application surfaces (28, 30) of the substrate (10), b) applying the second polymer functional material (14) by means of at least one application element (24, 60, 62) to an application surface (32) enclosed by the at least one first application surface (28, 30) or adjacent thereto.

2. Method according to claim 1, characterized in that according to method step a) a sealing adhesive is applied as the first polymer functional material (12).

3. Method according to claim 1, characterized in that according to method step b) an electrically conductive adhesive is applied as the second polymer functional material (14).

4. Method according to claims 1 to 3, characterized in that according to method step a) at least first application surfaces (28, 30) are moved over in a first or in a second feed direction (36, 38) by a first and third application element (22, 26).

5. Method according to claims 1 to 4, characterized in that according to method step b) a third application surface (32) is traversed by a second application element (24).

6. Method according to claims 1 to 5, characterized in that the application elements (22, 24, 26) are moved above a screen or a stencil (44).

7. Method according to claims 1 to 3, characterized in that the method steps a) and b) are carried out by a first application roller (60) on a first active side (52) of the substrate (10).

8. Method according to claims 1 to 3 and 7, characterized in that the method steps a) and b) are carried out by first and second application rollers (60, 62) on a first side and a second side (52, 54) of the substrate (10).

9. Method according to claims 1 to 3, 7 and 8, characterized in that the first polymer functional material (12) and the second polymer functional material (14) are removed from a material container (72) in which the first polymer functional material (12) and the second polymer functional material (14) are separated from one another by a spatial separation (74).

10. Method according to claims 1 to 3 and 7 to 9, characterized in that the first polymer functional material (12) and the second polymer functional material (14) are conveyed to the first application roller (60) and / or the second application roller (62) by means of an intermediate roller (64).

11. Method according to claims 1 to 3 and 7 to 10, characterized in that a first adhesive contour (80) or a second adhesive contour (82) is applied to the first active side (52) of the substrate (10) (MPP).

12. Method according to claims 1 to 3 and 7 to 10, characterized in that a first adhesive contour (80) and / or a second adhesive contour (82) are applied to the first active side (52) and the second active side (54) of the substrate (10) (BPP).

13. Use of the method according to claims 1 to 6 for applying at least two polymer functional materials (12, 14) by Screen or stencil printing for the production of monopolar or bipolar plates.

14. Use of the method according to claims 1 to 3 and 7 to 12 for applying at least two polymer functional materials (12, 14) for the production of monopolar plates or bipolar plates.

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