A grading double-face extrusion device for hydrogen production by alkaline electrolysis of water composite diaphragm phase inversion

Abstract

The utility model discloses a kind of hydrogen production of alkaline electrolytic water composite diaphragm phase inversion's hierarchical double-sided extrusion device, including pure water solidification tank and the first extrusion roller group and second extrusion roller group in its inside. Two groups of extrusion roller are including upper and lower extrusion roller oppositely arranged, and first extrusion gap is greater than second extrusion gap. The device carries out hierarchical double-sided extrusion in wet membrane phase inversion dynamic process simultaneously, preliminary compaction in front stage, and depth is rolled in rear stage. The hierarchical extrusion breaks passive film formation limit, can actively control coating microstructure, so that surface layer is dense and gas is separated, inner layer is porous and ion is guided;Simultaneously, slurry is forced to be physically embedded in support net fiber gap and form mechanical anchoring, greatly improve interface bonding force, effectively prevent coating from falling off in coagulation bath, and highly adapt composite diaphragm continuous production.

Description

Technical Field

[0001] This utility model relates to the field of alkaline water electrolysis hydrogen production technology, specifically to a staged double-sided extrusion device for phase conversion of a composite membrane in alkaline water electrolysis hydrogen production. Background Technology

[0002] The composite membrane for alkaline water electrolysis to produce hydrogen mainly consists of a polymer support network (such as PPS woven mesh) and a functional coating applied to it. The performance of this composite membrane largely depends on the microstructure of the coating. Ideally, the coating should have a dense surface layer to prevent hydrogen / oxygen cross-permeation, while having a loose and porous internal structure to facilitate ion transport.

[0003] Phase inversion method (NIPS) is one of the core technologies for preparing such composite membrane functional coatings: after coating the polymer solution onto the surface of the support mesh, the wet membrane is immersed in a coagulation bath, and the polymer is precipitated and solidified through the exchange of solvent and non-solvent, forming a coating with a porous structure.

[0004] However, existing technologies have the following shortcomings in the processing and phase transformation stages of composite membranes: (1) Lack of active mechanical control in the phase transformation stage: Existing composite membrane processing devices (such as the patent with publication number CN119036725A) usually adopt the method of directly entering the gas phase separation and liquid phase separation mechanism after coating. In the liquid phase separation (coagulation bath) stage, the wet membrane is only passively immersed in the coagulation bath by the guide roller. No extrusion or rolling structure is set up throughout the process, which makes it impossible to actively intervene and control the formation of coating pore structure during the phase transformation process, thus limiting the further improvement of membrane microstructure and physicochemical properties.

[0005] (2) The pressure application and phase transformation are carried out in steps, making it impossible to simultaneously solidify and anchor the coating: Existing preparation methods (such as the patent with publication number CN116377508A) propose applying pressure to the support mesh after impregnation with the casting solution before phase transformation to improve the coating adhesion and smoothness. However, the pressure application and phase transformation in this scheme are carried out in steps by static pressure application (such as applying pressure for 3-10 minutes before entering the coagulation bath), which cannot simultaneously compact and solidify the coating during the dynamic process of wet curing. At the same time, due to the low surface energy and strong chemical inertness of PPS fibers, static pressure application only before phase transformation makes it difficult for the slurry to be fully physically embedded in the fiber gaps during dynamic curing. The wet film still has the hidden danger of coating peeling and insufficient interfacial adhesion in the subsequent coagulation bath.

[0006] Therefore, developing a continuous production device that can achieve dynamic synchronous extrusion, actively control the coating structure, and enhance interfacial adhesion during the phase transformation stage has significant practical value. Utility Model Content

[0007] To address the aforementioned shortcomings in the existing technology, the purpose of this utility model is to provide a staged double-sided extrusion device for phase inversion of a composite diaphragm in alkaline water electrolysis for hydrogen production, aiming to solve the following technical problems: (1) Solve the problem that existing devices lack mechanical extrusion structures and cannot actively control the formation of pore structures during the phase transformation solidification bath stage; (2) Solve the problem that the existing technology involves pressure application and phase transformation in separate steps, resulting in the wet film lacking compaction and shaping during dynamic curing in the coagulation bath, and the coating and substrate having poor interfacial bonding and easy peeling.

[0008] To achieve the aforementioned objectives, the technical solution adopted by this utility model is as follows: A staged double-sided extrusion apparatus for alkaline water electrolysis hydrogen production using a composite membrane phase inversion is provided, comprising: a pure water coagulation tank containing a coagulation bath; and further comprising: The first extrusion roller group is disposed in the pure water coagulation tank, including a first upper extrusion roller and a first lower extrusion roller disposed opposite to each other, and a first extrusion gap is formed between the first upper extrusion roller and the first lower extrusion roller for the composite diaphragm to pass through. The second extrusion roller group is located inside the pure water coagulation tank and behind the first extrusion roller group. It includes a second upper extrusion roller and a second lower extrusion roller arranged opposite each other, and a second extrusion gap is formed between the second upper extrusion roller and the second lower extrusion roller for the composite diaphragm to pass through. Wherein, the first extrusion gap is larger than the second extrusion gap, so as to perform graded double-sided extrusion during the phase transformation dynamic process of the composite membrane.

[0009] Preferably, the first upper extrusion roller and / or the first lower extrusion roller, the second upper extrusion roller and / or the second lower extrusion roller are connected to a gap adjustment mechanism, which is used to independently adjust the size of the first extrusion gap and the second extrusion gap.

[0010] Preferably, the roller surfaces of the first upper extrusion roller, the first lower extrusion roller, the second upper extrusion roller, and the second lower extrusion roller are all covered with an elastic buffer layer.

[0011] Preferably, the range of the first extrusion gap is 0.4mm-0.6mm, and the range of the second extrusion gap is 0.2mm-0.35mm.

[0012] Preferably, the first extrusion gap is 0.5 mm, and the second extrusion gap is 0.3 mm.

[0013] Preferably, the first extrusion roller group and the second extrusion roller group are each connected to an independent drive motor, and the roller surface linear velocity of the first extrusion roller group is synchronized with the roller surface linear velocity of the second extrusion roller group.

[0014] Preferably, the pure water coagulation tank is further provided with a water inlet guide roller, which is located in front of the first extrusion roller group and / or behind the second extrusion roller group, for guiding the composite diaphragm's conveyor path in the coagulation bath.

[0015] Preferably, it also includes an unwinding mechanism, a coating mechanism, and a rewinding mechanism; The unwinding mechanism is used to transport the polymer support mesh substrate; the coating mechanism is used to coat the substrate surface with casting liquid slurry on both sides to form a wet film; the wet film is introduced into the pure water coagulation tank, and after passing through the first extrusion roller group and the second extrusion roller group in sequence for phase transformation and graded extrusion and shaping, it is continuously wound up by the winding mechanism.

[0016] The beneficial effects of this utility model are as follows: (1) Extrusion and phase transformation are carried out simultaneously to achieve active dynamic control of microstructure: The first and second extrusion roller groups are directly integrated and arranged inside the pure water coagulation box. Mechanical extrusion is carried out simultaneously during the dynamic process of solvent-non-solvent exchange (phase transformation) of the wet film, breaking the limitation of traditional passive film formation and realizing active, real-time and dynamic intervention in the formation of coating pore structure.

[0017] (2) Gradual dynamic pressure is adopted to balance density and porosity: This device adopts a graded extrusion structure with the roller gap size decreasing step by step along the direction of the diaphragm belt (e.g., 0.5 mm upstream roller gap and 0.3 mm downstream roller gap), and gradient dynamic pressure is completed during the wet film phase transformation and solidification process. When the wet film first enters the coagulation bath stage, the casting liquid has high fluidity. The upstream large roller gap only slightly levels and pre-presses the wet film, without damaging the porous skeleton that is forming inside the diaphragm. When the diaphragm moves to the downstream small roller gap station, the casting liquid on the surface of the diaphragm has undergone partial solvent-non-solvent exchange and the viscosity has increased significantly. At this time, the upper and lower extrusion rollers directly compact the surface of the diaphragm to form a dense water-proof and gas-proof layer, while the phase separation process of the inner layer of the diaphragm near the support mesh is delayed, and the internal porous ion transport channels are not damaged by the extrusion. This gradient pressure makes the surface of the coating denser by direct extrusion (achieving gas isolation), while the inner layer retains porous channels under the phase transformation (ensuring ion conduction), overcoming the contradiction that static single-stage pressure cannot balance density and porosity.

[0018] (3) Dynamic compaction promotes mechanical anchoring and effectively prevents coating detachment: This device performs dynamic double-sided graded extrusion in a wet environment of the coagulation bath, forcing the not-yet-fully-cured slurry to fully impregnate and physically embed into the fiber gaps of the PPS woven mesh under pressure, forming a strong mechanical interlocking structure. This effectively changes the weak bonding state of static pressure before phase transformation, greatly improves the anchoring bond between the coating and the substrate, and effectively prevents the coating from detaching during subsequent coagulation. At the same time, process integration simplifies the production line and is highly adaptable to continuous production lines. Attached Figure Description

[0019] Figure 1 This is a first-angle schematic diagram of the structure of the double-sided extrusion device of this utility model; Explanation of reference numerals in the attached drawings: 1-Coating mechanism; 2-Composite diaphragm; 3-Unwinding mechanism; 4-Water inlet guide roller; 5-First extrusion roller group; 6-Second extrusion roller group; 7-Rewinding guide roller; 8-Rewinding mechanism; 9-Pure water coagulation box.

[0020] Figure 2 This is a second-angle schematic diagram of the structure of the double-sided extrusion device of this utility model; Figure 3 This is a third-angle schematic diagram of the structure of the double-sided extrusion device of this utility model. Detailed Implementation

[0021] The specific embodiments of this utility model are described below to enable those skilled in the art to understand this utility model. However, it should be understood that this utility model is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of this utility model as defined and determined by the appended claims, these changes are obvious. All utility model creations utilizing the concept of this utility model are within the scope of protection.

[0022] Reference Figure 1 This embodiment provides a staged double-sided extrusion device for phase conversion of a composite membrane in alkaline water electrolysis for hydrogen production. The device mainly includes an unwinding mechanism 3, a coating mechanism 1, a pure water coagulation tank 9, and a winding mechanism 8.

[0023] The pure water coagulation tank 9 contains a coagulation bath. Inside the pure water coagulation tank 9, along the conveying direction of the composite diaphragm 2, a first extrusion roller group 5 and a second extrusion roller group 6 are arranged sequentially. Specifically, the first extrusion roller group 5 includes a first upper extrusion roller and a first lower extrusion roller arranged opposite each other, forming a first extrusion gap between them for the composite diaphragm 2 to pass through. The second extrusion roller group 6 is located behind the first extrusion roller group 5 and includes a second upper extrusion roller and a second lower extrusion roller arranged opposite each other, forming a second extrusion gap between them for the composite diaphragm 2 to pass through. The first extrusion gap is larger than the second extrusion gap to perform staged double-sided extrusion during the phase transformation dynamic process of the composite diaphragm 2.

[0024] In a preferred embodiment, the first extrusion gap can be set to 0.5 mm, and the second extrusion gap can be set to 0.3 mm. This preferred size was determined based on multiple control experiments in NIPS phase inversion film fabrication: suitable for conventional 80~120 μm coated wet films and standard belt speeds of 1.2~2 m / min. The effective working range of the first extrusion roller group is limited to 0.4~0.6 mm, and the effective working range of the second extrusion roller group is limited to 0.2~0.35 mm. If the first extrusion gap is <0.4 mm, the pre-compression load is too high, which will directly collapse the nascent porous skeleton inside the wet film, significantly reducing the ion conduction performance of the membrane. If the first extrusion gap is >0.6 mm, the pre-compaction effect is insufficient, the slurry cannot be fully embedded into the fiber gaps of the PPS support mesh, and the coating interface anchorage strength is insufficient, making it prone to detachment. If the second extrusion gap is less than 0.2 mm, excessive surface extrusion will completely block the ion transport channels, causing a surge in membrane resistance. If the second extrusion gap is greater than 0.35 mm, the surface densification is insufficient, leading to increased hydrogen and oxygen permeation across the membrane and substandard gas barrier performance. Only within the aforementioned gradient range can the coating interface bonding strength, surface gas barrier effect, and inner layer ion conductivity be simultaneously considered. Any size outside this range cannot balance these three core performance characteristics, making it difficult to achieve the same finished product effect.

[0025] To adapt to wet films with different coating thicknesses, match differentiated gradient compaction requirements, and ensure stable extrusion effects and equipment versatility under various working conditions, the first upper extrusion roller and / or the first lower extrusion roller, and the second upper extrusion roller and / or the second lower extrusion roller are all equipped with independent gap adjustment mechanisms. The two sets of roller gaps do not interfere with each other, and the size of the first extrusion gap and the second extrusion gap can be adjusted independently. The gap adjustment mechanism includes two preferred drive forms: a screw and nut pair mechanism can achieve micron-level precise fine adjustment of the roller gap, suitable for small-batch, high-precision diaphragm trial production; and a cylinder drive mechanism with fast adjustment speed and strong load-bearing capacity, suitable for high-speed continuous mass production lines. The two can be selected and used together according to production needs. At the same time, the wet film is in an incompletely cured state with extremely low coating strength. Direct extrusion by rigid metal rollers can easily scratch and crush the surface cast film coating. Therefore, the roller surfaces of the first upper extrusion roller, the first lower extrusion roller, the second upper extrusion roller, and the second lower extrusion roller are all covered with an elastic buffer layer. The buffer layer relies on its own deformation to evenly distribute the extrusion load, avoiding localized stress concentration that could damage the wet film. Three optional materials are available, each suitable for different scenarios: silicone is resistant to water bath corrosion and has a smooth surface that prevents material adhesion; polyurethane has a moderate elastic modulus and a long wear life; and nitrile rubber is resistant to swelling and suitable for long-term operation in solvent-containing coagulation baths. The elastic buffer layer can be made of silicone, polyurethane, or nitrile rubber.

[0026] In terms of power transmission, if there is a difference in the linear speed of the front and rear roller groups, it will pull and stretch the soft wet film in the bath, causing wrinkles, uneven thickness, or even tearing and scrapping of the film surface. Therefore, the first extrusion roller group 5 and the second extrusion roller group 6 are both equipped with independent servo drive motors. The two sets of motors share the same main control signal and perform real-time closed-loop speed regulation, so that the roller surface linear speed of the first extrusion roller group 5 and the roller surface linear speed of the second extrusion roller group 6 are strictly synchronized throughout the process, eliminating belt stretching defects and ensuring uniform and stable diaphragm size.

[0027] In addition, the conveyor belt angle is prone to deviation when the wet film enters the coagulation bath from the coating station. Direct entry into the roller group will cause film surface creases and one-sided force bias. Therefore, the pure water coagulation tank 9 is also equipped with a water inlet guide roller 4. The water inlet guide roller 4 is located on the upstream side of the first extrusion roller group 5 along the diaphragm conveyor belt direction. It limits and guides the wet film that has just been immersed in the coagulation bath, smoothly adjusts the conveyor belt angle, and smoothly guides the composite diaphragm 2 straight into the roller gap extrusion area to avoid diaphragm deviation and wrinkles.

[0028] In the actual workflow, the unwinding mechanism 3 is used to uniformly transport the polymer support mesh substrate; when the substrate passes through the coating mechanism 1, a casting liquid slurry is coated on both sides of the substrate surface to form a wet film; subsequently, the wet film is introduced into the pure water coagulation tank 9, and while undergoing a phase inversion reaction, it passes through the first extrusion roller group 5 and the second extrusion roller group 6 in sequence for graded extrusion and shaping; finally, the shaped composite diaphragm 2 is reversed and exported by the winding guide roller 7, and continuously wound up by the winding mechanism 8.

[0029] The specific workflow is as follows: First, the PPS woven mesh is pre-wound onto the unwinding mechanism 3, which then pulls the PPS woven mesh forward at a uniform speed. When the PPS woven mesh passes through the coating mechanism 1, the coating mechanism 1 extrudes slurry and coats it on both sides of the PPS woven mesh surface, forming a composite membrane 2 with a wet coating.

[0030] Subsequently, the coated composite membrane 2 is introduced into the pure water coagulation tank 9 containing pure water (coagulation bath liquid) through the water inlet guide roller 4. Inside the pure water coagulation tank 9, the composite membrane 2 undergoes a phase inversion (NIPS) coagulation reaction, that is, the solvent and non-solvent (water) are replaced, and the polymer is precipitated and solidified.

[0031] Unlike the passive immersion technology of the prior art, in the dynamic process of phase transformation, the composite diaphragm 2 passes sequentially through the first extrusion roller group 5 and the second extrusion roller group 6 within the pure water coagulation tank 9. The spacing (first extrusion gap) of the first extrusion roller group 5 is set to 0.5 mm for initial dynamic compaction; subsequently, it passes through the second extrusion roller group 6, with a spacing (second extrusion gap) set to 0.3 mm for further deep compaction. Through two-stage gradient extrusion, the coating is simultaneously compacted and shaped during the wet curing process of the diaphragm.

[0032] During the extrusion process, the wet slurry is dynamically forced into the fiber gaps of the PPS woven mesh, forming a strong mechanical anchor. At the same time, as the gaps gradually decrease, the surface of the coating is compacted and densified, while the interior retains a porous structure under phase transformation, thus forming an ideal asymmetric structure with a dense, air-barrier surface and a porous, ion-conducting interior.

[0033] Finally, the finished diaphragm, after phase inversion and shaping through graded double-sided extrusion, is reversed by the winding and turning roller 7, leaves the pure water coagulation box 9, and is continuously wound by the winding mechanism 8, completing the production line preparation of the entire composite diaphragm.

[0034] Comparative Example To verify the technical effectiveness of this utility model device, the following comparative tests were conducted: Sample A (this utility model): Using the above-mentioned device, with a first gap of 0.5mm and a second gap of 0.3mm, dynamic graded extrusion is carried out simultaneously in a coagulation bath (pure water).

[0035] Comparative Example B (Static Pre-compression Method): After coating, the coating is first statically compressed by the pressure roller for 3 minutes, and then enters the coagulation bath (without dynamic extrusion).

[0036] Comparative Example C (no extrusion method): After coating, the material is directly placed into the coagulation bath and guided only by guide rollers (conventional process).

[0037] In this comparative experiment, all irrelevant variables were uniformly controlled: 120 g / m³ was selected. 2 The three groups of samples were prepared under identical conditions: PPS woven support mesh, casting liquid solid content of 22%, wet film thickness of 100 μm, constant temperature of pure water coagulation bath at 25℃, and stable diaphragm conveyor speed of 1.5 m / min. The only difference between the three groups was the extrusion process; all other preparation conditions were identical. The measured performance data are as follows: Data shows that: Sample A (dynamic graded extrusion of this invention): peel strength 0.72 MPa, bubble point pressure 0.68 bar, ionic conductivity 11.6 mS / cm; Comparative Example B (static pre-compression method): peel strength 0.51 MPa, bubble point pressure 0.47 bar, ionic conductivity 11.2 mS / cm; Comparative Example C (no extrusion method): peel strength 0.36 MPa, bubble point pressure 0.32 bar, ionic conductivity 11.8 mS / cm.

[0038] The results show that, compared with the static pre-compression process, the peel strength of sample A, processed using the dynamic graded extrusion method of this invention, is increased by 41.2%, the gas barrier pressure at the bubble point is increased by 44.7%, and the ionic conductivity decreases only slightly by 3.6%. Compared with the conventional process without extrusion, the peel strength of sample C is directly increased by 100%, the gas barrier pressure is increased by 112.5%, and the ionic conductivity decreases by only 1.7%. This demonstrates that this device can simultaneously and significantly improve the interfacial adhesion between the coating and the substrate, and the gas barrier capability of the membrane, without almost sacrificing the ion conduction performance of the membrane, thus overcoming the contradiction that traditional processes cannot balance peel strength, gas barrier performance, and electrical conductivity.

[0039] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

Claims

1. A graded double-sided extrusion device for phase inversion of a composite separator for hydrogen production from alkaline electrolysis of water, comprising: A pure water coagulation tank (9), wherein the pure water coagulation tank (9) contains a coagulation bath liquid; characterized in that it further includes: The first extrusion roller group (5) is set in the pure water coagulation tank (9) and includes a first upper extrusion roller and a first lower extrusion roller arranged opposite to each other. A first extrusion gap is formed between the first upper extrusion roller and the first lower extrusion roller for the composite diaphragm (2) to pass through. The second extrusion roller group (6) is located inside the pure water coagulation tank (9) and behind the first extrusion roller group (5). It includes a second upper extrusion roller and a second lower extrusion roller arranged opposite to each other. A second extrusion gap is formed between the second upper extrusion roller and the second lower extrusion roller for the composite diaphragm (2) to pass through. The first extrusion gap is larger than the second extrusion gap, and is used for staged double-sided extrusion during the phase transformation process of the composite membrane.

2. The stepped double-sided extrusion apparatus according to claim 1, characterized in that, The first upper extrusion roller and / or the first lower extrusion roller, the second upper extrusion roller and / or the second lower extrusion roller are connected to a gap adjustment mechanism, which is used to independently adjust the size of the first extrusion gap and the second extrusion gap.

3. The apparatus of claim 1, wherein, The surfaces of the first upper extrusion roller, the first lower extrusion roller, the second upper extrusion roller, and the second lower extrusion roller are all covered with an elastic buffer layer.

4. The apparatus of claim 1, wherein, The first extrusion gap ranges from 0.4mm to 0.6mm, and the second extrusion gap ranges from 0.2mm to 0.35mm.

5. The stepped double-sided extrusion apparatus according to claim 4, wherein The first extrusion gap is 0.5 mm, and the second extrusion gap is 0.3 mm.

6. The staged double-belt press apparatus of claim 1, wherein, The first extrusion roller group (5) and the second extrusion roller group (6) are each connected to an independent drive motor, and the roller surface linear velocity of the first extrusion roller group (5) is synchronized with the roller surface linear velocity of the second extrusion roller group (6).

7. The apparatus of claim 1, wherein, The pure water coagulation tank (9) is also equipped with a water inlet guide roller (4), which is located in front of the first extrusion roller group (5) and is used to guide the composite diaphragm (2) in the coagulation bath.

8. A cascade double facer apparatus according to any one of claims 1 to 7, characterised in that, It also includes an unwinding mechanism (3), a coating mechanism (1), and a rewinding mechanism (8); The output end of the unwinding mechanism (3) corresponds to the coating mechanism (1), the output end of the coating mechanism (1) is connected to the pure water coagulation tank (9), and the output end of the pure water coagulation tank (9) is provided with the winding mechanism (8).

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