WO2003094270A2

WO2003094270A2 - Bipolar plate for fuel cell stacks and method for the production thereof

Info

Publication number: WO2003094270A2
Application number: PCT/EP2003/004563
Authority: WO
Inventors: Michael Götz
Original assignee: Proton Motor Fuel Cell Gmbh
Priority date: 2002-04-30
Filing date: 2003-04-30
Publication date: 2003-11-13
Also published as: WO2003094270A3; EP1532705A2; DE10219384A1; AU2003232240A1

Abstract

Disclosed is a bipolar plate for fuel cell stacks (2), which is characterized by the fact that said bipolar plate comprises a fiber-reinforcing structure (26), a plastic matrix (40), and an additive (42) in the plastic matrix in order to create electrical conductivity.

Description

Bipolar plate for fuel cell stacks and process for their manufacture

The invention relates to a bipolar plate for fuel cell stacks.

As is known, fuel cell stacks contain a stacked sequence of fuel cells (the axis of the stack being in particular vertical or horizontal), two adjacent fuel cells being separated from one another by a bipolar plate. On one side, each bipolar plate belongs to an anode side of a subsequent fuel cell, while the other side of the bipolar plate belongs to the cathode side of the other subsequent fuel cell. Since all fuel cells or at least some of the fuel cells of the fuel cell stack are electrically connected in series, an electric current flows across the thickness of each bipolar plate during operation of the fuel cell stack. Low electrical resistance of the material of the bipolar plate is a desirable property because greater electrical resistance is synonymous with heating the bipolar plate and thus generating losses. - Since in most cases there is essentially the same pressure on the anode side of a first subsequent fuel cell and on the cathode side of a second subsequent fuel cell, or a not very different pressure, the forces coming from the pressure difference on the bipolar plate are in most cases not great , On the other hand, in most cases, fuel cell stacks are clamped together by tie rods; Since the components of the individual fuel cells are normally not perfectly equally thick over the surface of the fuel cell, the forces coming from the clamping of the fuel cell stack on the bipolar plates are generally not evenly distributed over the surface of a bipolar plate under consideration. As a result, bipolar plates of fuel cell stacks are exposed to not insignificant mechanical loads. - At each end of the burning There is an end plate in the cell stack, which should not be called a bipolar plate when considering the meaning of the word. The end plates are often made of the same material as the bipolar plates inside the fuel cell stack; however, the end plates are sometimes made with a greater material thickness.

Bipolar plates for fuel cell stacks are known, which consist of plastic with an additive for creating electrical conductivity. In concrete terms, the use of thermoplastic and an addition of carbon distributed in the plastic (in the form of powdery particles and / or in the form of short carbon fibers) are known. Since the proportion of the additive has to be high for low electrical resistance, today's bipolar plates are normally well over a millimeter thick so that sufficient mechanical strength is ensured; a thickness of several millimeters is not uncommon. The electrical resistance of a bipolar plate increases in proportion to its thickness.

The invention is based on the technical problem of making a bipolar plate available in a construction which, with the same strength, leads to a reduced thickness of the bipolar plate. With the same specific electrical resistance, the electrical resistance is reduced by reducing the thickness of the bipolar plate. In addition, the dimension of the fuel cell stack decreases measured in the direction of the axis of the stack. The weight of the fuel cell stack is correspondingly reduced.

According to the invention, the stated technical problem is solved in that the bipolar plate

- a fiber reinforcement structure;

- a plastic matrix;

- and has an additive in the plastic matrix to create electrical conductivity. The fiber reinforcement structure provided according to the invention increases the mechanical strength of the bipolar plate so considerably - if the plastic and the guide additive are left unchanged compared with the prior art - that they achieve the same load-bearing capacity as in the prior art - Can be made significantly thinner than before.

As explained in more detail in the second paragraph of the description, the bipolar plate according to the invention can be a bipolar plate which, with its large sides, directly adjoins adjacent fuel cells. It is expressly emphasized that, alternatively, the bipolar plate according to the invention can also be suitable and intended such that it directly adjoins an anode side or a cathode side of a fuel cell with a first large side, but adjoins another bipolar plate with its second large side, which then in turn adjacent to a cathode side or an anode side of another fuel cell. In this case, a pair of bipolar plates has replaced a single bipolar plate between two adjacent fuel cells. An exemplary embodiment to be described further below will explain this in more detail. Such pairs of bipolar plates can be used particularly advantageously if the space between the two bipolar plates is used to allow gaseous or liquid cooling fluid to flow through them.

The fiber reinforcement structure is preferably a flat fiber reinforcement structure. "Flat" does not mean that the fiber reinforcement structure lies exactly in one plane. Rather, it should be expressed that the thickness of the fiber reinforcement structure is relatively small compared to the surface area when the fiber reinforcement structure is viewed from above.

The fiber reinforcement structure preferably has carbon fibers, particularly preferably it consists of carbon fibers. In addition to their high strength, carbon fibers have the important advantage of electrical conductivity for the bipolar plate. However, other fibers can also be used, in particular glass fibers and polyamide fibers. If you keep in mind that the fiber Reinforcement structure embedded in an electrically conductive plastic matrix and normally occupies a not very large volume portion of the bipolar plate, it is clear that electrically non-conductive fibers 105 are also useful.

Preferred forms of formation of the fiber reinforcement structure are oriented fiber layers (in which, for example, fibers lie somewhat parallel to one another; one can work well with two layers of fiber layers that cross one another), non-woven, also as needle-punched nonwoven, fabric, knitted fabric. Practically all types of fiber reinforcement structures customary in the field of fiber reinforcement of plastics can be used in the invention.

The plastic matrix preferably has a thermoset, particularly preferably an epoxy resin or a phenolic resin. In particular, relatively slow-curing thermosets can be processed particularly well with a fiber reinforcement structure. However, it is emphasized that other plastics, in particular thermoplastics, can also be used.

120 The conductive additive preferably has graphite particles, preferably flake graphite powder. Such particles introduce a high electrical conductivity into the plastic matrix.

The conductive additive preferably has ground carbon fibers.

125 Particularly suitable, ground carbon fibers are in a length range from 100 to 900 micrometers, particularly preferably 200 to 500 μm. It is very particularly preferred to use both flake graphite powder and additionally ground carbon fibers as additives. The relatively short carbon fibers bring a certain strength-increasing in the plastic matrix

130 effect on. However, they are not subsumed under the term fiber reinforcement structure in the context of the invention. A fiber reinforcement structure is preferably understood to mean a structure in which the fibers have at least a certain mutual cohesion. 135 The amount of the conductive additive is preferably 70 to 90 percent by mass of the total amount of plastic and additive. The introduction of such a large amount of additive is recommended to ensure a high electrical conductivity of the bipolar plate.

140 Thermosets are available that have a flowable consistency before hardening. The additive can be mixed into such thermosets. In the case of thermoplastics, it is possible to mix ground plastic particles in the solid state with the powdery additive. To facilitate the introduction of a large amount of the additive into liquid plastic

145 and in order to facilitate the further processing of the mixed material formed therefrom when brought together with the fiber reinforcement structure, it is preferred to add a, preferably volatile, solvent. Typical suitable solvents are isopropanol and acetone.

150 The bipolar plate preferably has a recessed flow channel arrangement on one side or on both sides and webs in between (“flowfield”). The flow channel arrangement can serve in particular to supply reactants, preferably hydrogen on the anode side of the respective fuel cell and air on the cathode side of the respective fuel cell. Which he-

155 bipolar plate according to the invention is particularly preferably used in fuel cell stacks whose fuel cells have a polymer electrolyte membrane ("PEM") and are operated with hydrogen and air as reactants.

160 The bipolar plate is preferably free of fiber reinforcement structure in the area of the webs of the flowfield, i.e. the fiber reinforcement structure is located in the massive "back" of the bipolar plate, which is located on one side of the flow channel arrangement or in the middle between two flow channel arrangements.

165

Bipolar plates according to the invention preferably have a back thickness of 0.4 to 0.6 mm (whereas known bipolar plates generally have a back thickness of more than 1 mm); if the bipolar plate has no flow has channel arrangement, the thickness of the back corresponds to the thickness of the bipolar plate. If there is a flow channel arrangement and webs in between, the thickness or height of the webs is 0.5 to 0.7 mm. No change is achieved here compared to the known bipolar plates, because one does not want to reduce the flow cross sections of the flow channels. In the case of bipolar plates with a flow field on one side, the total thickness is therefore preferably from 0.9 to 1.3 mm.

Another object of the invention is an arrangement of two bipolar plates, characterized in that it has a first bipolar plate with a flow channel arrangement on one side and a second bipolar plate with a 180 flow channel arrangement on both sides. The two bipolar plates of the pair are preferably designed as disclosed above for a single bipolar plate.

Another object of the invention is a method for producing a bi-polar plate for fuel cell stacks, characterized in that plastic and an additive which serves to create electrical conductivity are mixed to form a mixed material; that a fiber reinforcement structure is provided on one or both sides with the mixed material that is in a flowable state; and that the mixed material and the fiber reinforcement structure are formed in a press mold into a molded part for the bipolar plate.

The molded part removed from the press mold can already be the finished bipolar plate. Alternatively, further processing can be carried out after removal from the press mold, for example mechanical processing in the areas where tie rods are used to clamp the cell stack together. Apart from this or other post-processing, the method according to the invention leads to the bipolar 200 plate according to the invention. The method is preferably carried out more specifically in such a way that a molded part for a bipolar plate, as has been described so far, is produced. The features disclosed above as preferred features of the bipolar plate are also preferred features of the method according to the invention.

205 The fiber reinforcement structure is preferably impregnated with a further mixing material which is in a flowable state and has plastic and an additive which creates electrical conductivity, before it is provided with the aforementioned mixing material. In this way, a pre-impregnated fiber reinforcement structure is produced that is easier with the

210 first-mentioned mixed material, which forms the hardened plastic matrix, can be provided. It is good to apply the additional mixing material for impregnation in a relatively thin state in order to optimally wet the fiber reinforcement structure.

215 The plastic of the further mixed material preferably has a thermoset, particularly preferably consists of a thermoset, epoxy resin or phenolic resin being particularly preferred. However, other plastics than thermosets are also possible, e.g. Thermoplastics. It is particularly favorable if the plastic of the other mixed material is the same as the plastic.

220 material of the first-mentioned mixed material.

The addition of the further mixing material preferably has graphite particles, particularly preferably flake graphite powder. The addition of ground graphite fibers mentioned above for the first-mentioned mixed material is also possible with the other mixed material, but is not particularly preferred. Without the addition of ground graphite fibers, the additional mixed material embeds the fiber reinforcement structure more optimally.

When the impregnation 230 is carried out, the further mixed material preferably contains solvents, isopropanol and acetone being mentioned as particularly suitable. The same applies to the first-mentioned mixed material if the fiber reinforcement structure is provided with it. In the case of the further mixed material, it is more likely that even stronger thin liquid will be sought in the impregnation than in the first-mentioned mixed material.

235 The fiber reinforcement structure is preferably provided with the first-mentioned mixing material after the solvent has at least largely evaporated from the further mixing material. In this way, the further mixing material remains better in place if the fiber reinforcement structure is provided with the first mixing material.

The fiber reinforcement structure and the first-mentioned mixed material are preferably brought together in the press mold. If the fiber reinforcement structure is provided on one side with the first-mentioned mixed material

245, the fiber reinforcement structure - if necessary impregnated with the other mixed material - can be placed first in the open mold and then covered with a layer of the first-mentioned mixed material. If the fiber reinforcement structure is to be provided on both sides with the first-mentioned mixing material, one can in particular

250 first insert a layer of the first-mentioned mixed material into the open mold, then place the - optionally impregnated - fiber reinforcement structure and finally apply another layer of the first-mentioned mixed material. Alternatively, it is preferred that the fiber reinforcement structure, optionally impregnated, be unilateral outside the press mold

255 or on both sides with a layer of the first-mentioned mixed material and only then insert the whole into the mold. The latter preferably only occurs when the solvent preferably contained in the first-mentioned mixed material has evaporated at least to a considerable extent. If you put the first-mentioned mixed material in the mold

260, it is best to leave the mold open for a while to facilitate the evaporation of at least a substantial part of the preferred solvent before the mold is closed. The solvent is evaporated from the first-mentioned mixed material preferably at room temperature under reduced pressure (vacuum chamber).

265 mer); but you can also work at elevated temperatures; you can also work without negative pressure. Analogous, preferred process features apply to the evaporation of the preferably provided solvent of the further mixed material. In general, however, the evaporation of the solvent from the other mixed material is much easier because the other 270 mixed material is applied in a small amount or thin layer to impregnate the fiber reinforcement structure.

The fiber reinforcement structure is preferably impregnated with the further mixing material in a production step which lies before the fiber reinforcement structure is inserted into the press mold. However, it is also possible to impregnate the fiber reinforcement structure in the state already inserted into the press mold.

The pressure is preferably applied to the filled mold after the solvent from the first-mentioned mixed material has largely evaporated. Any remaining pores in the plastic can be closed by means of the pressure on the filled mold.

The mold is preferably heated to harden the plastic of the first-mentioned mixed material, if appropriate also to harden the plastic of the further mixed material. Heating to a suitable curing temperature for the plastic accelerates curing and leads to the best final strength of the bipolar plate.

290 If one speaks above of a bipolar plate provided with a flow channel arrangement or of a fiber reinforcement structure provided on one side with a first mixed material, it can be a matter of producing end plates for the fuel cell stack; But it can also be about bipolar plates, which are due to the specific structure of the fuel cell stack

295 have a flowfield on only one side; Finally, it can be a question of bipolar plates which are used in pairs with a bipolar plate provided with flow field on both sides. 300 The invention and preferred embodiments of the invention are explained in more detail below using an exemplary embodiment. It shows:

1 shows a detail of a fuel cell stack, in a section parallel to the axis of the stack;

305

Fig. 2 shows a bipolar plate from the fuel cell stack of Fig. 1, on an enlarged scale and a section according to II-II in Fig. 1, i.e. parallel to the axis of the stack, but with a position of the cutting plane perpendicular to the cutting plane of FIG. 1;

310

Figure 3 shows an empty mold in a sectional view.

4 shows a pair of bipolar plates in a representation analogous to FIG. 2.

315 A section of a fuel cell stack 2 is shown in FIG. 1. Specifically, one can see a complete fuel cell 4, formed from a central polymer electrolyte membrane 6, above an anode-side gas diffusion electrode 8, including a cathode-side gas diffusion electrode 10, above the gas diffusion electrode 8 of a bipolar plate 12 (which is, as it were, half of the

320 considered fuel cell 4), and below the gas diffusion electrode 10 of an identical bipolar plate 12 (which can be assigned with its upper half of the fuel cell 4 under consideration). The axis of the fuel cell stack 2 is designated 14 and shown as a broken line. In plan view of the flat side of the not shown, above

325 ren end plate of the stack 2, the stack has a square or rectangular shape. Tension anchors are indicated schematically by the dash-dotted lines 16, which are provided in the four corner regions of the stack 2 and clamp the entire stack together. Specifically, one has to imagine about ten to fifty fuel cells 4 in the stack 2. The stacking axis 14 can in particular

330 in particular run vertically (then FIG. 1 is a vertical section with a horizontal viewing direction) or can run horizontally (then FIG. 1 is a horizontal section with a viewing direction from top to bottom). The flow channel arrangements 18a and 18k can be concretely conceived together as a 335 channel. A possible alternative is a number of channels running in parallel, which is fed through a distribution channel running transversely thereto and ends at the end in a transverse collection channel.

340 The polymer electrolyte membrane 6 is provided on each flat side with a noble metal catalyst, which is not shown. The gas diffusion electrodes 8 and 10 can consist of an electrically conductive, gas-permeable fleece. The bipolar plates each have a flow channel arrangement 18 in their upper flat side as well as in their lower flat side

345 is indicated schematically as an arrangement of channel-like depressions 20 with webs 22 in between. Hydrogen is supplied to the fuel cell through the flow channel arrangement 18a adjacent to the anode-side gas diffusion electrode 8 (arrow H ₂ ). The fuel cell 4 becomes air through the flow channel arrangement 18k adjacent to the cathode-side gas diffusion electrode 10

350 fed (arrow "air"). Air which is not consumed in the reaction in the fuel cell 4, and also contains water formed by the chemical reaction in the fuel cell 4, leaves the fuel cell 4 under consideration according to the arrow "Air 4- H ₂ O". The above description naturally applies to all fuel cells 4 of the stack 2.

355 |

2 illustrates how a preferred bipolar plate 12 according to the invention is constructed.

The bipolar plate 12 shown has a total thickness 24. Approximately in the central 360 region of the total thickness 24 there is a fiber reinforcement structure 26, shown here as a fabric made of threads which in turn consist of carbon fibers.

A section of the flow channel arrangement 18a can be seen at the bottom in FIG. 2. A section of the 365 flow channel arrangement 18k lying behind the plane of the drawing is indicated in a broken line at the top in FIG. 2. Apart from the fiber reinforcement structure 26, the material of the bipolar plate 12 is a hardened epoxy resin, which 80% by mass (the total mass of Ep- oxide resin and additive, without the solvent) of an electrical conductivity-imparting additive, which in turn consists predominantly of flake graphite powder and the rest of ground carbon fibers with a fiber length of about 350 microns.

FIG. 3 shows a mold 30 on a scale like FIG. 2. The mold 30 has a lower, higher mold part 32 and an upper mold part 375 34, which can be removed.

The production of the bipolar plate 12 from FIG. 2 preferably proceeds as follows:

380 Outside the mold 30, the fiber reinforcement structure 26 is first provided with an impregnation. The "further material mixture" used for impregnation consists of not yet hardened epoxy resin, solvent and about 80% by mass (based on the total mass of epoxy resin and additive, without the solvent) flake graphite powder. By means of the

385 the "further material mixture" is adjusted so thin that it e.g. can be used by brushing or spraying to conveniently impregnate the fiber reinforcement structure 26.

Alternatively, you can work without the impregnation.

390

After the solvent of the impregnation has at least largely evaporated, the fiber reinforcement structure 26 is placed on a support, e.g. a film, placed, and a layer of a "first-mentioned material mixture" is applied to the free top. You let some of the solution

395 degassing and then turns the fiber reinforcement structure 26 coated on one side to another base, e.g. Foil. Now the other large side of the fiber reinforcement structure 26 is provided with a layer of the "first-mentioned material mixture". The resulting structure is then allowed to gas out thoroughly, preferably with the help of heat

400 and / or negative pressure. This structure is then used in the lower molded part 32 shown in FIG. 3. The upper molding 34 is placed. It will Pressure is applied to compress the mold parts 32 and 34 and the closed mold 30 is placed in an oven. At the elevated temperature in the furnace, the thermoset hardens both the "first-mentioned material mixture" 405 and the "further material mixture". The mold 30 is then removed from the oven and opened. The shaping therein is removed, mechanically processed and then represents the bipolar plate 12.

Alternatively, one can first introduce a lower layer of the "first-mentioned material mixture" into the lower molded part 32, then put on the fiber reinforcement structure 26, and then apply an upper layer of the "first-mentioned material mixture".

2 shows a bipolar plate 12 with a flow channel arrangement 18 415 on both sides. The total thickness 24 is, for example, 1.7 mm, the thickness or height of the flow channel arrangement 18 or the webs 20 being, for example, 0.6 mm on each side, so that for the thickness 52 of the “back” between the flow channel arrangements 18 0, 5 mm remain. This is considerably thinner than with conventional bipolar plates.

420

It is pointed out that in the case of a bipolar plate 12 provided with a flow channel arrangement 18 on one side, the layer thickness of the “first-mentioned material mixture” on the side of the fiber reinforcement structure 26 facing away from the flow channel arrangement 18 is as small as possible, that is to say considerably 425 smaller than in the case of a bipolar plate 18 provided on both sides with a flow channel arrangement 18 12th

A suitable epoxy resin is an epoxy resin from Rhenatech, Kempen, offered under the designations 5100 and 5600 (resin and hardener). On

430 suitable product for the ground carbon fibers is Sigrafil C10 M 350EPY from SGL Carbon, Meitingen. In this product, the carbon fibers have a diameter of approximately 8 μm and a length in the region of 350 μm. When purchased, the carbon fibers are sized with very little epoxy resin and therefore work particularly well with organic solvents. On

A suitable product for the flake graphite powder is MA 399 SC from the company NGS natural graphite, Leinburg. In this product, at least 80% of the graphite particles have a size that is smaller than a sphere 45 µm in diameter.

440 Figure 4 shows what a pair of bipolar plates 12a and 12b look like. One bipolar plate 12a is provided on both sides with a flow channel arrangement 18, like the bipolar plate 12 shown in FIG. 2. The other bipolar plate 12b is only provided with a flow channel arrangement 18 on one side. Bipolar plate 12b is smooth (i.e., not flow channel assembly 18)

445 provided) side against the first bipolar plate 12a. The space between the bipolar plates 12a and 12b can serve as a channeled flow space 54 for the passage of gaseous or liquid cooling fluid, in particular a mixture of water and conventional antifreeze.

450

Claims

455PATENTANSPRÜCHE

1. Bipolar plate for fuel cell stack (2), 460 characterized in that it

- Fiber reinforcement structure (26);

- a plastic matrix (40);

- And an additive (42) in the plastic matrix to create electrical conductivity

465.

2. Bipolar plate according to claim 1, characterized in that a flat fiber reinforcement structure (26) is provided.

470

3. Bipolar plate according to claim 1 or 2, characterized in that the fiber reinforcement structure (26) comprises carbon fibers.

475 4. Bipolar plate according to one of claims 1 to 3, characterized in that the fiber reinforcement structure (26) has a directional fiber layer or a fleece or a fabric or a knitted fabric.

480 5. Bipolar plate according to one of claims 1 to 4, characterized in that the plastic matrix (40) has a thermoset, preferably an epoxy resin or a phenolic resin.

6. Bipolar plate according to one of claims 1 to 4, 485 characterized in that the plastic matrix (40) has a thermoplastic.

7. Bipolar plate according to one of claims 1 to 6, characterized in that the additive (42) has graphite particles, preferably flake graphite powder.

490

8. Bipolar plate according to one of claims 1 to 7, characterized in that the additive (42) has ground carbon fibers.

495 9. Bipolar plate according to one of claims 1 to 8, characterized in that the amount of additive (42) is 70 to 90 percent by mass of the total amount of plastic and additive.

10. bipolar plate according to one of claims 1 to 9,

500 characterized in that they recessed on one or both sides

Flow channel arrangement (18) and webs (22) between them.

1 1. Bipolar plate according to claim 10, characterized in that it is free of Fa 505 server strengthening structure (26) in the region of the webs (22).

12. Arrangement of two bipolar plates, characterized in that they have a first bipolar plate (12) according to claim 10 or 11 with one-sided flow channel arrangement (18) and a 510 second bipolar plate (12) according to claim 10 or 11 with bilateral

Flow channel arrangement (18).

515

13. A method for producing a bipolar plate (12) for fuel cell stacks (2),

520 characterized in that plastic (40) and an additive (42), which serves to create electrical conductivity, are mixed to form a mixed material; that a fiber reinforcement structure (26) is provided on one or both sides with the mixed material which is in a flowable state

525 will; and that the mixed material and the fiber reinforcement structure (26) are formed in a press mold (30) into a molded part for the bipolar plate (12).

14. The method according to claim 13,

530 characterized in that a molded part for a bipolar plate (12) according to one of claims 2 to 11 is produced.

15. The method according to claim 13 or 14, characterized in that the fiber reinforcement structure (26), before it is 535 provided with said mixing material, with another

Mixing material is impregnated, which is in a flowable state and has plastic and an electrical conductivity additive.

540 16. The method according to claim 15, characterized in that the plastic of the further mixing material comprises a thermoset, preferably an epoxy resin or a phenolic resin.

545 17. The method according to claim 15, characterized in that the plastic of the further mixed material has a thermoplastic.

18. The method according to claim 15 or 16, characterized in that the plastic of the further mixing material 550 is equal to the plastic of the first-mentioned mixing material.

19. The method according to any one of claims 15 to 18, characterized in that the addition of the further mixing material comprises graphite particles, preferably flake graphite powder.

555

20. The method according to any one of claims 15 to 19, characterized in that the further mixed material, when the impregnation is carried out, contains solvents.

560 21. The method according to any one of claims 13 to 20, characterized in that the first-mentioned mixing material, when the fiber reinforcement structure (26) is provided with it, contains solvents.

565 22. The method according to claim 20 or 21, characterized in that the fiber reinforcement structure (26) is provided with the first-mentioned mixing material after the solvent has at least largely evaporated from the additional mixing material.

23. The method according to any one of claims 13 to 22, characterized in that the fiber reinforcement structure (26) and the first-mentioned mixed material are brought together in the press mold (30).

575

24. The method according to any one of claims 15 to 23, characterized in that the fiber reinforcement structure (26) is impregnated with the 580 further mixing material in a manufacturing step which is before the fiber reinforcement structure (26) is inserted into the press mold (30).

25. The method according to any one of claims 13 to 22 or claim 24,

585 characterized in that the fiber reinforcement structure (26) and the first-mentioned mixed material are brought together in one production step, which lies before the fiber reinforcement structure (26) is inserted into the press mold (30).

590 26. The method according to any one of claims 21 to 25, characterized in that the pressure is applied to the filled mold (30) after the solvent has at least largely evaporated from the first-mentioned mixed material.

595 27. The method according to any one of claims 13 to 26, characterized in that the press mold (30) is heated to harden the plastic (40) of the first-mentioned mixed material, optionally also to harden the plastic of the further mixed material.