Hot pressing structure utilizing continuous isostatic pressing and preparation method of CCM

Abstract

The invention relates to the technical field of fuel cell preparation, in particular to a hot-pressing structure utilizing continuous isostatic pressing and a preparation method of a CCM, the hot-pressing structure comprises a first conveying roller, a second conveying roller and a third conveying roller which are sequentially arranged from top to bottom, and the hot-pressing structure is characterized by further comprising a base, the base is provided with a feeding roller and a discharging roller which are arranged along the conveying direction of the proton membrane, the feeding roller and the discharging roller are coated with a metal belt, the metal belt is internally provided with pressing plates, and the pressing plates are arranged on the upper side and the lower side of the proton membrane. According to the invention, the processing quality of the CCM can be improved while the production efficiency of the CCM is maintained.

Description

Technical Field

[0001] This invention relates to the technical field of fuel cell fabrication, and in particular to a method for fabricating a hot-pressed structure and CCM using continuous isostatic pressing. Background Technology

[0002] Catalyst Coated Membrane (CCM) transfer is a process that involves transferring a catalyst layer (CL) pre-prepared on a release membrane (carrier membrane) completely to both sides of a proton exchange membrane (PEM) using a hot-pressing process, forming a sandwich-structured core component (CCM). Its core objective is to avoid the problems associated with directly coating catalyst slurry onto the fragile and easily swollen PEM (such as membrane deformation, catalyst permeation, and solvent damage to the membrane). Essentially, its working principle utilizes thermodynamics and interface science principles, employing precisely controlled temperature, pressure, and time to achieve an efficient, complete, and damage-free transfer of the catalyst layer from the easily coated and processed temporary carrier (release membrane) to the final substrate (proton exchange membrane). This technology is one of the core processes for manufacturing high-performance, long-life fuel cell CCMs.

[0003] Currently, the most common transfer equipment used for preparing CCMs are flatbed hot presses and roller transfer machines. Specifically, in a flatbed hot press, transfer film A, proton exchange membrane, and transfer film B are pre-placed between upper and lower pressure plates in a top-to-bottom order. The pressure plates are then closed, and the transfer films A, B, and CCMs are heated and pressurized to complete the transfer. Roller transfer machines have multiple sets of conveyor rollers arranged in a top-to-bottom order for transfer film A, B, and CCMs. These rollers continuously transport the films, and during transport, heating rollers are used to apply pressure and heat for the transfer process.

[0004] However, in practical use, flatbed hot presses require the insertion of transfer film A, proton exchange membrane, and transfer film B each time a transfer is performed. After the transfer is completed, the CCM is removed, and then transfer film A, proton exchange membrane, and transfer film B are reinserted, resulting in low production efficiency. Although roller transfer machines can perform continuous transfers, the contact between the heated roller and transfer films A and B is close to line contact, with a very small contact area, making it difficult to control the uniform pressure distribution. Summary of the Invention

[0005] In order to maintain CCM production efficiency while improving CCM processing quality, this invention provides a hot-pressed structure utilizing continuous isostatic pressing and a method for preparing CCM.

[0006] This invention provides a hot-pressed structure utilizing continuous isostatic pressing, employing the following technical solution: A hot pressing structure utilizing continuous isostatic pressure includes a first conveying roller, a second conveying roller, and a third conveying roller arranged sequentially from top to bottom, and a base. The base is provided with an infeed roller and an outlet roller arranged along the proton exchange membrane conveying direction. The infeed roller and the outlet roller are covered with a metal strip, and a pressure plate is provided inside the ring formed by the metal strip. The pressure plate is located on the upper and lower sides of the proton exchange membrane.

[0007] In one specific implementation, the pressure plate has an isostatic pressure cavity, and the metal strip passes through the isostatic pressure cavity to close the opening of the isostatic pressure cavity.

[0008] In one specific implementation, both the feed roller and the discharge roller are hollow.

[0009] In one specific implementation, multiple sets of pressure plates are arranged along the proton exchange membrane transport direction.

[0010] In one specific implementation, a heat insulation layer is provided between adjacent groups of pressure plates.

[0011] In one specific implementation, the metal strip is an alloy material strip capable of withstanding a tension of 10 to 20 tons.

[0012] This invention also provides a method for preparing CCM, which adopts the following technical solution: A method for preparing a CCM, used in conjunction with the aforementioned hot-pressed structure utilizing continuous isostatic pressing, further includes the following steps: Transporting transfer membranes and proton exchange membranes; According to the preparation requirements, the transfer film and proton exchange membrane are preheated or cooled by a metal strip; The pressure plate heats and presses the transfer film and proton exchange membrane to perform the transfer process; After the transfer is completed, rewind the CCM and release film.

[0013] In summary, the present invention has the following beneficial effects: 1. The pressure plate can uniformly heat and pressurize the conveyed transfer film and proton exchange membrane to ensure the processing quality of CCM. The first, second and third conveying rollers realize the automatic conveying of the transfer film and proton exchange membrane, maintain the preparation efficiency of CCM, and achieve good processing quality of CCM while maintaining the processing efficiency of CCM.

[0014] 2. The feed roller and discharge roller heat or cool the metal strip, which can preheat and cool the transfer film and proton exchange membrane, thus improving the processing quality of CCM. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of a hot-pressed structure utilizing continuous isostatic pressure.

[0016] Explanation of reference numerals in the attached drawings: 1. First conveying roller; 2. Second conveying roller; 3. Third conveying roller; 4. Base; 5. First feed roller; 6. First discharge roller; 7. First metal strip; 8. Upper pressure plate; 9. Second feed roller; 10. Second discharge roller; 11. Second metal strip; 12. Lower pressure plate. Detailed Implementation

[0017] The following combination Figure 1 The present invention will be described in further detail below.

[0018] The hot pressing structure utilizing continuous isostatic pressing includes a first conveying roller 1, a second conveying roller 2, and a third conveying roller 3 arranged sequentially from top to bottom. The first conveying roller 1 conveys the transfer film A, the second conveying roller 2 conveys the proton exchange membrane, and the third conveying roller 3 conveys the transfer film B.

[0019] It also includes a base 4, on which inlet rollers and outlet rollers are arranged along the proton exchange membrane conveying direction, between the first conveying roller 1. The inlet rollers and outlet rollers are covered with a metal strip, specifically a steel strip in this embodiment, but in some other embodiments it can be an alloy material strip capable of withstanding 10-20 tons of tension. A pressure plate for the transfer operation is installed inside the ring formed by the metal strip.

[0020] For ease of description, the feed rollers and discharge rollers on the upper and lower sides of the proton exchange membrane are distinguished by the first feed roller 5, the first discharge roller 6, the second feed roller 9, and the second discharge roller 10. The first feed roller 5 and the first discharge roller 6 are located above the proton exchange membrane. The first metal strip 7 is on the first feed roller 5, and the second metal strip 11 is on the second feed roller 9. The upper pressure plate 8 is located between the first feed roller 5 and the first discharge roller 6, and the lower pressure plate 12 is located between the second feed roller 9 and the second discharge roller 10.

[0021] An upper static pressure chamber is formed on the upper pressure plate 8, with the opening of the upper static pressure chamber facing the lower pressure plate 12. A first metal strip 7 passes through the opening of the upper static pressure chamber. A lower static pressure chamber is formed on the lower pressure plate 12, with the opening of the lower static pressure chamber facing the upper pressure plate 8. A second metal strip 11 passes through the opening of the lower static pressure chamber.

[0022] During the transfer process, a heat-conducting medium is introduced into the upper and lower isostatic pressure chambers through the side walls of the upper pressure plate 8 and the lower pressure plate 12. The first metal strip 7 seals the upper isostatic pressure chamber, and the second metal strip 11 seals the lower isostatic pressure chamber. Due to the surface tension of the heat-conducting medium, even with minute gaps between the first metal strip 7 and the upper pressure plate 8, and between the second metal strip 11 and the lower pressure plate 12, the heat-conducting medium cannot leak. The heat-conducting medium uniformly heats the first metal strip 7 and the second metal strip 11, thereby uniformly heating the transfer film A through the first metal strip 7 and the transfer film B through the second metal strip 11, further achieving uniform heating of the transfer film A, the proton exchange membrane, and the transfer film B during the transfer process. Simultaneously, since pressure is also applied to the first metal strip 7 and the second metal strip 11 through the heat-conducting medium, the upper pressure plate 8, and the lower pressure plate 12, uniform heating and pressurization during the transfer process are achieved, minimizing edge effects.

[0023] The edge effect occurs in flatbed hot presses. Because the press plates are heated by electric heating rods, the heat gradually decreases as the radiation range of the heating rods decreases. As a result, the temperature and pressure at the edge of the press plate are lower than those at the center. In severe cases, the temperature difference between the edge and the center of the press plate may be as high as 3°C.

[0024] Furthermore, since the pressure between the upper pressure plate 8 and the lower pressure plate 12 is adjustable, compared to a roller transfer machine, by stopping the conveying of transfer film A, the proton exchange membrane, and transfer film B, the pressure holding time between the upper pressure plate 8 and the lower pressure plate 12 can be extended, thereby ensuring the migration rate of transfer film A and transfer film B on the proton exchange membrane and the bonding strength after transfer. While retaining the continuous conveying of the roller transfer machine, it also enables long-term pressure holding in a hot press. Moreover, the upper pressure plate 8 and the lower pressure plate 12 have a larger heating and pressure holding area compared to the heating rollers of the roller transfer machine, further ensuring the migration rate of transfer film A and transfer film B on the proton exchange membrane and the bonding strength after transfer.

[0025] It is understandable that the holding time of transfer film A, proton exchange membrane and transfer film B between the upper pressure plate 8 and the lower pressure plate 12 is determined according to the manufacturing requirements of CCM. When the holding time of CCM is short and the required pressure is low, the continuous conveying of transfer film A, proton exchange membrane and transfer film B can be achieved by extending the length of the upper pressure plate 8 and the lower pressure plate 12 in the proton exchange membrane conveying direction, so as to carry out continuous production of CCM.

[0026] It should be noted that in this invention, multiple sets of upper pressure plates 8 and lower pressure plates 12 can be arranged along the proton exchange membrane transport direction. A heat insulation layer is provided between adjacent sets of upper pressure plates 8 and lower pressure plates 12 to reduce heat transfer between adjacent upper pressure plates 8 and adjacent lower pressure plates 12. The heat insulation layer can be a metal plate or a heat insulation material plate. By setting multiple sets of upper pressure plates 8 and lower pressure plates 12, a temperature gradient change is achieved during the transfer process. For example, if five sets of upper pressure plates 8 and lower pressure plates 12 are arranged along the proton exchange membrane transport direction, the temperature of the first two sets of upper pressure plates 8 and lower pressure plates 12 gradually increases at 80°C and 100°C, reaching a peak of 160°C with the third set of upper pressure plates 8 and lower pressure plates 12. Afterward, the temperature of the fourth and fifth sets of upper pressure plates 8 and lower pressure plates 12 gradually decreases at 100°C and 80°C. By changing the temperature gradient, the shrinkage rate of transfer membrane A, proton exchange membrane and transfer membrane B can be effectively reduced, so that the prepared CCM is warp-free. This can improve the migration rate of transfer membrane A and transfer membrane B on the proton exchange membrane and the binding strength after transfer, thereby improving the quality of CCM.

[0027] The feed roller and discharge roller can also be hollow, and a heat-conducting medium can be introduced into the feed roller and discharge roller to heat or cool them, thereby heating or cooling the metal strip and preheating or cooling the transfer film A and transfer film B before transfer printing, thus improving the transfer effect.

[0028] This invention also discloses a method for preparing a CCM, which employs the above-mentioned hot pressing structure utilizing continuous isostatic pressing, and is configured such that heating is required during the transfer process, and further includes the following steps: S1, the first conveying roller 1 conveys the transfer film A, the second conveying roller 2 conveys the proton exchange membrane, and the third conveying roller 3 conveys the transfer film B.

[0029] S2, a heat-conducting medium is introduced into the feed roller and discharge roller to preheat the metal strip. During the rolling of the metal strip, the transfer film A, proton exchange film, and transfer film B are uniformly preheated. A heat-conducting medium is introduced into the pressure plate to heat the pressure plate and apply pressure to the metal strip.

[0030] S3, when the transfer film A, proton exchange membrane and transfer film B enter between the pressure plates, the pressure plates move closer together to squeeze the transfer film A, proton exchange membrane and transfer film B, and transfer pressure and heat are transferred to the transfer film A, proton exchange membrane and transfer film B through the metal strip to perform transfer and obtain CCM.

[0031] S4, after the transfer is completed, the second conveyor roller 2 winds up the CCM, and the first conveyor roller 1 and the second conveyor roller 2 wind up the remaining release film of the transfer film A and the transfer film B respectively.

[0032] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A hot pressing structure utilizing continuous isostatic pressing, comprising a first conveying roller (1), a second conveying roller (2), and a third conveying roller (3) arranged sequentially from top to bottom, characterized in that: It also includes a base (4), on which feed rollers and discharge rollers are arranged along the proton exchange membrane conveying direction. The feed rollers and discharge rollers are covered with metal strips, and a pressure plate is provided in the ring formed by the metal strips. The pressure plate is located on the upper and lower sides of the proton exchange membrane.

2. The hot-pressed structure utilizing continuous isostatic pressing according to claim 1, characterized in that: An isostatic pressure cavity is provided on the pressure plate, and the metal strip passes through the isostatic pressure cavity to close the opening of the isostatic pressure cavity.

3. The hot-pressed structure utilizing continuous isostatic pressing according to claim 1, characterized in that: Both the feed roller and the discharge roller are hollow.

4. The hot-pressed structure utilizing continuous isostatic pressing according to claim 1, characterized in that: Multiple sets of pressure plates are arranged along the proton exchange membrane transport direction.

5. The hot-pressed structure utilizing continuous isostatic pressing according to claim 4, characterized in that: A heat insulation layer is provided between the pressure plates of adjacent groups.

6. The hot-pressed structure utilizing continuous isostatic pressing according to claim 1, characterized in that: The metal strip is an alloy material strip capable of withstanding a tension of 10 to 20 tons.

7. A method for preparing CCM, characterized in that: When used in conjunction with the hot-pressed structure utilizing continuous isostatic pressing as described in any one of claims 1-6, the method further includes the following steps: For the transport of transfer membranes and proton exchange membranes; According to the preparation requirements, the transfer film and proton exchange membrane are preheated or cooled by a metal strip; The pressure plate heats and presses the transfer film and proton exchange membrane to perform the transfer process; After the transfer is completed, rewind the CCM and release film.

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