Electrolytic cell composite sealing material and preparation method

Abstract

The present application relates to the technical fields of electrolytic cell sealing material, and particularly relates to a kind of electrolytic cell composite sealing material and preparation method.It includes anti-seepage layer, composite matrix layer and interface transition layer;The anti-seepage layer is microporous polytetrafluoroethylene layer, and the microporous polytetrafluoroethylene layer has through-hole structure;The interface transition layer is fluorine-containing siloxane network layer;The composite matrix layer includes elastomer phase, sheet-shaped insulating heat-conducting filler and layered ion capture filler, the surface of sheet-shaped insulating heat-conducting filler has fluorosilane treatment layer, and the surface of layered ion capture filler has fluorine-containing organosilane treatment layer;The present application forms mechanical embedding by in-situ construction and infiltration of fluorine-containing siloxane network interface transition layer of through-hole between microporous polytetrafluoroethylene anti-seepage layer and composite matrix layer, sets the thickness direction gradient distribution of layered ion capture filler on the near-interface side of composite matrix layer, improves interface barrier and stability to inhibit electrolyte along interface migration leakage.

Description

Technical Field

[0001] This invention relates to the field of electrolytic cell sealing materials, and in particular to a composite sealing material for electrolytic cells and its preparation method. Background Technology

[0002] When an electrolyzer operates in an alkaline or saline electrolyte environment, the sealing components need to effectively block the electrolyte and maintain a stable seal under conditions such as assembly tightening, temperature changes, and media immersion. In addition to the media resistance of the body material, the bonding stability of the interfaces between the structural layers (such as the barrier layer and the elastomer support layer) of the sealing components also affects the risk of leakage during long-term use.

[0003] In the prior art, there are proposed solutions for reinforced composite materials that combine porous or expanded polytetrafluoroethylene (PTFE) structures with elastomer materials. For example, US20030211264A1 discloses an ePTFE-reinforced elastomer composite material, in which at least a portion of the composite material is made "substantially non-permeable" by impregnating the elastomer emulsion into the pores of the ePTFE, and can be used to form media-resistant elastomer composite articles (e.g., pump tubes). Furthermore, in the lamination bonding of fluoropolymer substrates and silicone rubber, there are also solutions that improve the bonding strength by surface activation and the introduction of silane coupling agents. For example, EP2074188A1 discloses plasma treatment of a plastic or PTFE / fluoropolymer substrate to activate surface functional groups, followed by coating the surface with a liquid silicone rubber composition containing a silane coupling agent and curing to obtain a laminated film structure and improve interlayer bonding strength.

[0004] In addition, from the perspective of material systems, US6447918B1 also discloses an interpenetrating polymer network layer structure containing PTFE and cured polysiloxane elastomer to obtain specific surface layer properties.

[0005] However, for sealing conditions involving long-term immersion in electrolyte and under load in electrolytic cells, the aforementioned approaches, while involving technologies such as "porous PTFE and elastomer composites," "surface activation + silane-promoted bonding," and "PTFE / siloxane network systems," may still present problems in certain situations. When the interfacial bonding between the impermeable layer and the composite matrix layer is not stable enough, micro-defects at the interface may evolve into migration channels extending along the interlayer interface under long-term media action, thereby increasing the risk of electrolyte penetration along the interface and leading to seal failure. US20030211264A1 focuses on achieving low permeability characteristics of composite materials through impregnation filling, but it does not explicitly disclose the construction of a controlled interface transition structure within the porous PTFE through-holes for the electrolytic cell sealing interface. Although EP2074188A1 discloses coating with silane-containing liquid silicone rubber after plasma treatment to improve lamination bonding, its focus is on improving the bonding strength of the laminated film structure, and it does not provide a specific structured interface solution for suppressing interface migration channels under electrolytic cell conditions.

[0006] Therefore, a major technical problem that needs to be solved by existing technologies is: how to enhance the interfacial bonding and interfacial barrier stability between the polytetrafluoroethylene (PTFE) anti-seepage layer and the elastomer composite matrix layer under the long-term action of the electrolyte in the electrolytic cell, so as to suppress the leakage risk caused by the migration of electrolyte / ions along the interface. Summary of the Invention

[0007] To overcome the above-mentioned technical defects, the present invention aims to provide a composite sealing material for electrolytic cells and a preparation method thereof. The present invention forms a mechanical embedding by constructing an in-situ fluorinated siloxane network interface transition layer with through-holes between the microporous polytetrafluoroethylene anti-seepage layer and the composite matrix layer, and by infiltrating the through-holes. At the same time, a layered ion-capturing filler is set with a thickness gradient distribution near the interface of the composite matrix layer, thereby improving the interface barrier and stability to suppress electrolyte migration and leakage along the interface.

[0008] This invention discloses a composite sealing material for an electrolytic cell, comprising an impermeable layer, a composite matrix layer, and an interface transition layer disposed between the impermeable layer and the composite matrix layer;

[0009] The impermeable layer is a microporous polytetrafluoroethylene layer, which has a through-pore structure.

[0010] The interface transition layer is a fluorinated siloxane network layer, which is formed by the hydrolysis and condensation of fluorinated alkyltrialkoxysilane and epoxytrialkoxysilane. The fluorinated siloxane network layer penetrates into the through-pores of the microporous polytetrafluoroethylene layer to form a mechanically embedded structure.

[0011] The composite matrix layer includes an elastomer phase, sheet-like insulating and thermally conductive filler, and layered ion-trapping filler. The surface of the sheet-like insulating and thermally conductive filler has a fluorosilane treatment layer, and the surface of the layered ion-trapping filler has a fluorinated organosilane treatment layer.

[0012] Among them, the layered ion trapping filler is distributed in a thickness gradient in the composite matrix layer, and in the thickness range of 0 to 0.30 mm with the surface of the composite matrix layer near the interface transition layer as the starting point, the mass fraction of the layered ion trapping filler is higher than the mass fraction in the other thickness range of the composite matrix layer.

[0013] Preferably, the average pore size of the microporous polytetrafluoroethylene layer is 0.05 to 5 micrometers, and the penetration depth of the fluorinated siloxane network layer into the microporous polytetrafluoroethylene layer is 5 to 120 micrometers.

[0014] Preferably, the fluorinated siloxane network layer further comprises silicon-carbon bonds formed by the addition reaction of vinylsilane and silanolsilane, and both vinylsilane and silanolsilane form an interpenetrating structure with the condensation product of epoxytrialkoxysilane.

[0015] Preferably, the elastomer phase is a two-phase structure formed by dynamic vulcanization, the two-phase structure including an ethylene propylene rubber phase and a fluorosilicone rubber phase, wherein the ethylene propylene rubber phase is a continuous phase, the fluorosilicone rubber phase is a dispersed phase, and the volume fraction of the fluorosilicone rubber phase is 10% to 45%.

[0016] Preferably, the layered ion-capturing packing is a compound of layered double hydroxide and fluorinated anion exchange resin, and the layered double hydroxide and fluorinated anion exchange resin exist in the form of composite particles within a thickness range of 0 to 0.30 mm.

[0017] Preferably, the sheet-like insulating and thermally conductive filler is sheet-like boron nitride, and the sheet-like boron nitride is oriented within the composite matrix layer, with the angle between the normal of the sheet-like boron nitride and the thickness direction of the electrolytic cell composite sealing material being 0 to 30 degrees.

[0018] Preferably, the composite matrix layer further includes a reactive ion-pair crosslinking system, which includes a quaternary ammonium salt grouped polymer and a sulfonate grouped polymer, and the reactive ion-pair crosslinking system and the peroxide crosslinking system together constitute a composite crosslinking structure.

[0019] Preferably, the composite sealing material of the electrolytic cell is a frame-type sealing gasket, which is integrally formed with a flange sealing rib along the circumference. The flange sealing rib is formed by the composite matrix layer, and the anti-seepage layer continuously covers the top and inner surfaces of the flange sealing rib.

[0020] In view of this, a second objective of the present invention is to provide a method for preparing the electrolytic cell composite sealing material as described above, comprising:

[0021] S1, a microporous polytetrafluoroethylene layer is provided as a seepage barrier, and the seepage barrier is subjected to plasma surface activation to form an activated surface;

[0022] S2, prepare a fluorinated siloxane network precursor sol, the fluorinated siloxane network precursor sol contains fluorinated alkyl trimekoxysilane and epoxy trimekoxysilane.

[0023] S3, apply the fluorinated siloxane network precursor sol to the activated surface and perform hydrolysis and condensation to form an interface transition layer in situ on the surface of the impermeable layer, and during the formation process, the interface transition layer penetrates into the through pores of the impermeable layer.

[0024] S4, Prepare a composite matrix layer compound, wherein the composite matrix layer compound comprises at least an elastomer phase, a sheet-like insulating and thermally conductive filler with a fluorosilane treatment layer on the surface, and a layered ion-trapping filler with a fluorine-containing organosilane treatment layer on the surface.

[0025] S5, prepare an enriched film near the interface transition layer and a matrix film away from the interface transition layer, wherein the mass fraction of the layered ion-capturing filler in the enriched film is higher than the mass fraction of the layered ion-capturing filler in the matrix film; stack the enriched film and the matrix film to form a composite matrix layer preform with a thickness gradient distribution, and stack the composite matrix layer preform with an impermeable layer having an interface transition layer.

[0026] S6. The composite material is pressurized and heated to form a composite matrix layer and cross-linked and cured to obtain an electrolytic cell composite sealing material.

[0027] Preferably, the plasma surface activation in step S1 includes processing conditions of 100-800 watts power and 5-180 seconds processing time, and the working gas of the plasma includes a mixture of argon and oxygen.

[0028] Preferably, the fluorinated siloxane network precursor sol in step S2 further comprises vinyl silane and silane, and the addition reaction of vinyl and silane occurs simultaneously during the hydrolysis-condensation process in step S3.

[0029] Preferably, in step S3, after the fluorinated siloxane network precursor sol is applied, a negative pressure is applied to the impermeable layer so that the interface transition layer enters the through-pores of the impermeable layer during the formation process and reaches a penetration depth of 5 to 120 micrometers.

[0030] Preferably, the enrichment film and the substrate film in step S5 are formed by partitioned laying, which includes laying the enrichment film on the side close to the interface transition layer and laying the substrate film on the side away from the interface transition layer.

[0031] Preferably, in step S4, the sheet-like insulating thermally conductive filler is oriented, including calendering and shearing orientation, and the calendered film is cooled and shaped before crosslinking and curing in step S6 to maintain the orientation distribution.

[0032] Preferably, the pressurized heating molding in step S6 simultaneously completes the integral molding of the flange sealing rib of the frame-type sealing gasket, and during the molding process, the anti-seepage layer continuously covers the top and inner surfaces of the flange sealing rib.

[0033] Compared with existing technologies, the above technical solution has the following advantages:

[0034] 1. This invention achieves a stable interfacial bond between the geomembrane and the composite matrix layer by constructing an interfacial transition layer in situ on the surface of the microporous polytetrafluoroethylene geomembrane and allowing it to penetrate into the through-holes to form an embedded structure, thereby reducing the risk of interfacial delamination and peeling.

[0035] 2. This invention creates a gradient partition between the enrichment film and the substrate film in the thickness direction of the composite matrix layer, allowing the layered ion-capturing filler to be directionally enriched near the interface, thus satisfying the sealing contact requirements while inhibiting the migration of electrolyte and ions in the thickness direction.

[0036] 3. This invention improves the overall thermal conductivity and insulation synergy of the composite matrix layer in both the thickness direction and the in-plane direction by calendering and shearing the sheet-like insulating and thermally conductive filler for orientation and cooling and shaping before crosslinking and curing, thereby forming a controlled orientation distribution.

[0037] 4. This invention introduces vinylsilane and silane hydrosilane into the sol system and allows them to undergo simultaneous addition reactions during hydrolysis and condensation, making the interfacial transition layer network structure more compact and continuous, thereby improving the structural stability and resistance to media action of the interfacial transition layer.

[0038] 5. This invention uses negative pressure to assist the interface transition layer to enter the through-hole of the impermeable layer during the formation process and controllably reach a preset penetration depth, thereby improving the consistency and repeatability of the embedded structure within the pore and enhancing batch stability.

[0039] 6. This invention achieves integral molding of the flange sealing rib of the frame-type sealing gasket during the pressurized heating molding process, and controls the seepage-proof layer to continuously cover the top and inner surfaces of the sealing rib, so that a continuous seepage-proof path is formed in the key sealing parts, reducing the risk of local leakage.

[0040] 7. This invention improves the interfacial compatibility and dispersion stability between the filler and the elastomer phase by treating the surface of the ion-capturing filler with fluorinated organosilane and the surface of the sheet-like insulating and thermally conductive filler with fluorosilane, which is beneficial to maintaining the structural uniformity and mechanical stability of the composite matrix layer.

[0041] 8. This invention achieves a comprehensive balance of material sealing performance, ion barrier capability, and insulation and thermal conductivity by synergistically compounding elastomeric phase, sheet-like insulating and thermally conductive filler, and layered ion-capturing filler, and by combining it with zoned material laying and orientation shaping processes. It is suitable for the long-term service requirements of sealing parts of electrolytic cells. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the thickness gradient distribution of the layered ion-capturing packing material.

[0043] Figure 2 This is a schematic flowchart of a method for preparing a composite sealing material for an electrolytic cell according to the present invention;

[0044] Figure 3 This is a schematic diagram showing the cumulative leakage amount as a function of immersion time.

[0045] Figure 4 This is a schematic diagram showing the change of potassium ion migration index with soaking time.

[0046] Figure 5 This is a schematic diagram of the interface and composite matrix layer microstructure. Detailed Implementation

[0047] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0048] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0049] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0050] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0051] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0052] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0053] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0054] This embodiment provides a composite sealing material for an electrolytic cell, including an impermeable layer, a composite matrix layer, and an interface transition layer disposed between the impermeable layer and the composite matrix layer. The impermeable layer is a microporous polytetrafluoroethylene (PTFE) layer with a through-pore structure. The interface transition layer is a fluorinated siloxane network layer, which is formed by the hydrolytic condensation of fluorinated alkyltrialkoxysilane and epoxytrialkoxysilane, and the fluorinated siloxane network layer penetrates into the through-pores of the microporous PTFE layer to form a mechanically embedded structure. The composite matrix layer includes an elastomeric phase, a sheet-like insulating and thermally conductive filler, and a layered ion-trapping filler. The surface of the sheet-like insulating and thermally conductive filler has a fluorosilane treatment layer, and the surface of the layered ion-trapping filler has a fluorinated organosilane treatment layer. The layered ion-trapping filler is distributed in a thickness gradient in the composite matrix layer, and within a thickness range of 0 to 0.30 mm (measured from the surface of the composite matrix layer near the interface transition layer), the mass fraction of the layered ion-trapping filler is higher than the mass fraction within the remaining thickness range of the composite matrix layer.

[0055] For ease of understanding and description, this embodiment will provide a detailed description of an electrolytic cell composite sealing material through the following Examples 1 to 3, as follows.

[0056] Example 1 (Lower value):

[0057] This embodiment provides a composite sealing material for an electrolytic cell, the structure of which is as follows: Figure 1As shown, the structure includes, from top to bottom, a microporous polytetrafluoroethylene (PTFE) layer, a fluorinated siloxane network layer, and a composite matrix layer. The fluorinated siloxane network layer is disposed between the microporous PTFE layer and the composite matrix layer, and it penetrates into the through-pores of the microporous PTFE layer to form a mechanically embedded structure. The composite matrix layer contains sheet-like insulating and thermally conductive fillers and layered ion-trapping fillers, with the layered ion-trapping fillers exhibiting a gradient distribution along the thickness direction of the composite matrix layer. A schematic diagram of the gradient distribution can be found in [reference needed]. Figure 1 The sheet-like insulating and thermally conductive filler is oriented within the composite matrix layer.

[0058] Raw materials and pretreatment:

[0059] The microporous PTFE layer is made of expanded PTFE (ePTFE) film with an average pore size of 0.05 micrometers (lower end value) and a film thickness of 100 micrometers. The film has a through-pore structure. To reduce the influence of surface impurities on the network formation of the interface transition layer, the microporous PTFE layer is first wiped twice with anhydrous ethanol, then wiped once with deionized water, and dried under 60°C hot air circulation for 30 minutes before use.

[0060] The sheet-like insulating and thermally conductive filler is selected as sheet-like boron nitride, with a median particle size of 10 micrometers and a sheet diameter-to-thickness ratio greater than 10. To form a fluorosilane-treated layer, sheet-like boron nitride is added to a solution with a volume ratio of 95 / 5 ethanol / deionized water. A fluorosilane coupling agent (fluorinated alkyltriethoxysilane can be selected) is added to make its mass fraction 1%. The pH of the solution is adjusted to 4.5-5.5 and stirred for 30 minutes to complete the hydrolysis pretreatment. Then, the sheet-like boron nitride is added to the above solution and ultrasonically dispersed for 20 minutes, followed by mechanical stirring for 2 hours. After filtration, it is dried at 110℃ for 2 hours to obtain sheet-like boron nitride with a fluorosilane-treated layer on the surface.

[0061] The layered ion-capturing packing material is a composite of layered double hydroxide and fluorinated anion exchange resin. The layered double hydroxide is selected from magnesium-aluminum type layered double hydroxide powder, and the fluorinated anion exchange resin is a microsphere resin containing quaternary ammonium salt exchange groups and a fluorinated polymer backbone. The layered double hydroxide powder and the fluorinated anion exchange resin are mixed at a mass ratio of 60 / 40, and a small amount of ethanol is added to form a wet agglomerate. Composite particles are formed by low-shear granulation, with the particle size controlled between 50 and 200 micrometers. To form a fluorinated organosilane treatment layer, the composite particles are added to an ethanol solution along with a fluorinated organosilane coupling agent (optionally a fluorinated alkyl silane) to a mass fraction of 0.5%. After stirring for 1 hour, the mixture is filtered and dried at 80°C for 4 hours to obtain composite particles with a fluorinated organosilane treatment layer on the surface.

[0062] The elastomer phase adopts a dynamically vulcanized biphase structure composed of ethylene propylene rubber and fluorosilicone rubber, wherein ethylene propylene rubber is the continuous phase and fluorosilicone rubber is the dispersed phase; in this embodiment, the lower end value is used, and the volume fraction of the fluorosilicone rubber phase is 10%. The reactive ion-pair crosslinking system uses quaternary ammonium salt grouped polymers and sulfonate grouped polymers; the peroxide crosslinking system uses a combination of peroxide crosslinking agent and co-crosslinking agent.

[0063] Plasma surface activation of microporous polytetrafluoroethylene layers:

[0064] The microporous PTFE layer was placed in a plasma treatment device using an argon-oxygen mixture as the working gas, with argon comprising 90% of the volume and oxygen 10% by volume, and a total gas flow rate of 200 standard milliliters per minute. The treatment power was set to 100 watts and the treatment time to 5 seconds, thus creating an activated surface on one side of the microporous PTFE layer. After treatment, the layer was allowed to stand in a clean environment for no more than 10 minutes before proceeding to the next step to reduce interfacial differences caused by the decay of the activated surface.

[0065] Preparation and in-situ network formation of fluorinated siloxane network precursor sol:

[0066] Anhydrous ethanol was used as the solvent, and deionized water was added to control the volume ratio of ethanol to deionized water at 90 / 10. Fluoroalkyltrialkoxysilane and epoxytrialkoxysilane were added under stirring to achieve a molar ratio of 1 / 1, and a small amount of glacial acetic acid was added to adjust the pH of the system to approximately 5 to promote the controllable hydrolysis-condensation. Stirring was continued for 30 minutes to complete the hydrolysis-prepolymerization. Subsequently, vinylsilane and silanol silane were added to achieve an equivalent ratio of vinyl to silanol silane of 1 / 1, and a diluted platinum-based addition catalyst was added to control the platinum content at the level of 10 ppm, so that the addition reaction would occur synergistically with the condensation process in the subsequent curing stage without premature gelation.

[0067] The aforementioned fluorinated siloxane network precursor sol was applied to the activated surface of a microporous polytetrafluoroethylene (PTFE) layer using a blade coating method, with the wet film thickness controlled at approximately 20 micrometers. The applied microporous PTFE layer was then placed in a negative pressure chamber, and a negative pressure of 0.02 MPa was applied and maintained for 10 seconds to encourage the precursor sol to penetrate the through-pore structure. The negative pressure was then released, and the layer was left at room temperature for 10 minutes to complete initial condensation. Finally, it was heated at 80°C for 30 minutes to complete gelation and curing, resulting in a fluorinated siloxane network layer covering the surface of the microporous PTFE layer and penetrating the through-pores. To meet the lower limit requirements, this embodiment controlled the penetration depth of the fluorinated siloxane network layer into the through-pores to 5 micrometers by controlling the negative pressure amplitude and holding time. The penetration depth was confirmed by measuring the depth of the interface transition layer entering the pores through frozen sectioning of the sample under a scanning electron microscope.

[0068] Preparation of composite matrix layer compound, formation of two-phase structure and introduction of composite crosslinking system:

[0069] The composite matrix layer compounding employs a two-stage mixing method to reduce uneven dispersion caused by early reactions in the crosslinking system. In the first stage of mixing, ethylene propylene rubber is fed into an internal mixer and plasticized for 2 minutes at a rotor speed of 40 rpm and a chamber temperature of 60°C. Then, fluorosilicone rubber is added and mixing continues for 3 minutes to form the initial blend system. Subsequently, fluorosilane-treated flake boron nitride is added and mixing continues for 5 minutes, controlling the sheet temperature to not exceed 90°C. In the second stage of mixing, the rubber compound obtained in the first stage is returned to the internal mixer. At a rotor speed of 30 rpm, layered ion-trapping filler composite particles with a fluorinated organosilane-treated surface, quaternary ammonium salt-based polymers, and sulfonate-based polymers are added sequentially. After mixing for 4 minutes, the peroxide crosslinking system is added and mixed for 2 minutes, controlling the sheet temperature to not exceed 80°C, to obtain the composite matrix layer compound.

[0070] To form a biphase structure through dynamic vulcanization, the ethylene propylene rubber phase preferentially forms a continuous backbone during the subsequent molding and curing stage, while the fluorosilicone rubber phase exists as a dispersed phase, with the volume fraction of the fluorosilicone rubber phase controlled at 10%. To form a reactive ion-pair crosslinking system, the quaternary ammonium salt grouped polymer and the sulfonate grouped polymer are uniformly dispersed during the mixing process and form an ion-pair interaction network during the curing stage. Simultaneously, the peroxide crosslinking system forms a chemical crosslinking network, thereby constituting a composite crosslinking structure.

[0071] Construction of gradient distribution in layered ion-trapping packing (implementation of lower-end values):

[0072] This embodiment uses the lower end of the gradient enrichment thickness. To maintain the gradient characteristics while achieving the minimum thickness, this embodiment adopts the "interface-side surface enrichment" method: layered ion-capturing filler composite particles are rapidly mixed with a small amount of composite matrix compound on a two-roll mill to form an extremely thin enriched surface film. This enriched surface film is then applied to the surface of the composite matrix compound near the interface transition layer. The actual thickness of this enriched surface film is controlled to be no greater than 0.01 mm, so that it can be recorded as 0 mm under conventional cross-sectional measurement resolution, while still meeting the gradient distribution requirement that "the mass fraction near the interface transition layer is higher than the rest of the thickness range". A macroscopic illustration of the gradient distribution can be found in [reference needed]. Figure 1 .

[0073] The orientation distribution of plate-like boron nitride is formed (lower value orientation angle):

[0074] The composite matrix compound is calendered and sheared for orientation on a calender. The calender roll temperature is controlled at 50–60°C, the roll gap is set to 2.0 mm, and the calendering is performed in three passes. By controlling the calendering shear strength, the orientation angle of the lamellar boron nitride is controlled to 30°, that is, the angle between the normal of the lamellar boron nitride sheet and the thickness direction of the composite sealing material in the electrolytic cell is 30°. After calendering, the film is cooled and shaped to maintain the orientation distribution.

[0075] The stacked molding process is integrated with the frame-type sealing gasket.

[0076] A microporous polytetrafluoroethylene (PTFE) layer with a fluorinated siloxane network layer is laminated with a composite matrix film, ensuring contact between the fluorinated siloxane network layer and the composite matrix layer. During lamination, the enriched surface film on the interface side is positioned closer to the fluorinated siloxane network layer. The laminate is then placed into a frame-type sealing gasket mold for compression molding at 160°C, 3MPa, and a holding time of 5 minutes, while simultaneously forming an integral flange sealing rib. To ensure continuous coverage of the top and inner surfaces of the flange sealing rib by the microporous PTFE layer, it is pre-extended and laid to the top and inner walls of the sealing rib forming cavity during molding, allowing it to conform to the shape and cure together with the interface transition layer and the composite matrix layer during molding, thereby obtaining… Figure 1 The covering structure shown.

[0077] Comparative Examples and Comparative Tests (Exemplary Recorded Values):

[0078] For comparison, the comparative example was configured with a structure of "direct lamination and curing of a microporous polytetrafluoroethylene layer and an elastomer composite matrix layer," wherein a mechanically embedded structure without a fluorinated siloxane network layer entering the through-pores was not formed, and the layered ion-trapping filler in the composite matrix layer was uniformly dispersed without a gradient distribution. The test employed simulated electrolytic cell clamping conditions: the sample was mounted in a fixture and a fixed clamping stress was applied, followed by immersion in a 30% potassium hydroxide solution at 80°C for 168 hours. The interfacial peel strength, leakage, and potassium ion concentration in the outer collection solution were tested, as well as the compression set after immersion. Exemplary recorded values ​​are shown in Table 1-1.

[0079] Comparison Test Records (Example 1; Exemplary Record Values) Table 1-1

[0080]

[0081] Example 2 (intermediate value):

[0082] This embodiment provides a composite sealing material for an electrolytic cell, the structure of which is still as described above. Figure 1 As shown, see the gradient distribution diagram. Figure 1The difference from Example 1 is that this example takes intermediate values ​​for the key range parameters to achieve a more balanced in-hole embedding region, gradient enrichment region and orientation structure.

[0083] Raw materials and pretreatment:

[0084] The microporous PTFE layer is made of expanded PTFE film with an average pore size of 2.5 micrometers (intermediate value) and a film thickness of 100 micrometers. The cleaning and drying process for the microporous PTFE layer is the same as in Example 1.

[0085] The sheet boron nitride is still used and a fluorosilane treatment layer is formed. The treatment solution and hydrolysis pretreatment method are the same as in Example 1. However, in order to improve the dispersion stability of the intermediate value system, the mass fraction of the fluorosilane coupling agent is adjusted to 0.8%. The drying conditions after treatment are 110°C and 2 hours.

[0086] The layered ion capture packing still uses layered double hydroxides and fluorinated anion exchange resins to form composite particles and form a fluorinated organosilicon treatment layer; in order to facilitate the formation of a stable gradient, the particle size of the composite particles is controlled in the range of 80 to 250 micrometers to enhance the distinguishability between the enrichment layer and the matrix layer.

[0087] The elastomer phase adopts a dynamically vulcanized biphase structure composed of ethylene propylene rubber and fluorosilicone rubber. In this embodiment, an intermediate value is taken, with the volume fraction of the fluorosilicone rubber phase being 27.5%. The selection of reactive ion-pair crosslinking system and peroxide crosslinking system is consistent with that in Example 1.

[0088] Plasma surface activation (intermediate value):

[0089] The microporous polytetrafluoroethylene layer is placed in a plasma treatment device, using a mixture of argon and oxygen gas with an argon gas integral of 90% and an oxygen volume fraction of 10%, and a total flow rate of 200 standard milliliters per minute; the treatment power is 450 watts and the treatment time is 90 seconds, forming an activated surface and proceeding to the next step within 10 minutes.

[0090] Formation of fluorinated siloxane network precursor sol and embedded zone within pores (intermediate penetration depth):

[0091] The composition and preparation order of the precursor sol were consistent with those in Example 1. The molar ratio of fluorinated alkyltrialkoxysilane to epoxytrialkoxysilane was maintained at 1 / 1, and hydrolysis prepolymerization was carried out for 30 minutes using an ethanol / water volume ratio of 90 / 10 and a pH of approximately 5. The equivalent ratio of vinylsilane to silanol was maintained at 1 / 1, and the platinum addition catalyst was controlled at the level of 10 ppm. The coating method was still blade coating, and the wet film thickness was controlled at approximately 25 micrometers.

[0092] After application, negative pressure was applied to assist penetration, with a negative pressure amplitude of 0.05 MPa maintained for 40 seconds, to promote the entry of the precursor sol into the through-holes and form a more continuous embedded zone within the pores. Subsequently, the mixture was left at room temperature for 10 minutes to complete initial condensation, and then heated at 80°C for 45 minutes to complete gelation and curing. By controlling the negative pressure parameters and heat treatment time, the penetration depth of the fluorosiloxane network layer into the through-holes was controlled to 62.5 micrometers (intermediate value), and the measurement method was consistent with that in Example 1.

[0093] Preparation of composite matrix layer compound, biphase structure and composite crosslinking structure:

[0094] The composite matrix layer compounding still employs a two-stage compounding process. In the first stage, ethylene propylene rubber (EPR) and fluorosilicone rubber are blended, controlling the fluorosilicone rubber phase volume fraction to 27.5%, and flake-shaped boron nitride treated with fluorosilane is added. The sheeting temperature of the first stage is controlled to not exceed 95°C. In the second stage, layered ion-trapping filler composite particles with a fluorinated organosilane-treated surface are added, along with quaternary ammonium salt-based polymers and sulfonate-based polymers to form a reactive ion-pair crosslinking system. Finally, a peroxide crosslinking system is added, controlling the sheeting temperature to not exceed 85°C, resulting in the composite matrix layer compound. During the curing stage, a composite crosslinking structure is formed, consisting of both an ion-pair interaction network and a chemical crosslinking network.

[0095] Gradient enrichment region construction (intermediate value thickness):

[0096] In this embodiment, the intermediate gradient enrichment thickness is set at 0.15 mm. To form a stable and measurable gradient enrichment region, this embodiment employs a "rich film / matrix film overlay" method: a compound containing a high mass fraction of layered ion-capturing filler composite particles is calendered into an enrichment film, and a compound containing a low mass fraction of layered ion-capturing filler composite particles is calendered into a matrix film. The enrichment film thickness is controlled at 0.15 mm, and the matrix film thickness is set according to the final thickness requirement. During overlay, the enrichment film is laid on the side closest to the fluorosiloxane network layer, and the matrix film is laid on the side away from the fluorosiloxane network layer, so that the layered ion-capturing filler forms a gradient distribution in the thickness direction of the composite matrix layer. See the diagram for an illustration. Figure 1 It should be noted that, in Figure 1 The left side is the side closest to the interface transition layer. Figure 1 The right side of the image represents the transition layer away from the interface. Figure 1 The value in the middle represents the mass fraction (gradient enrichment) of the layered ion-capturing packing material.

[0097] Plate-like boron nitride orientation (intermediate orientation angle):

[0098] The laminated composite matrix film is calendered and sheared for orientation on a calendering machine at a roll temperature of 50–60°C and a roll gap of 1.8 mm for 5 passes. The shearing intensity is controlled by the number of calendering passes and the roll gap to keep the sheet boron nitride orientation angle at 15°. After calendering, the film is cooled and shaped to maintain the orientation.

[0099] The stacked molding process is integrated with the frame-type sealing gasket.

[0100] A microporous polytetrafluoroethylene (PTFE) layer with a fluorinated siloxane network layer and pre-formed in-pore embedded regions is laminated with a composite matrix layer, positioning the enriched film closer to the fluorinated siloxane network layer. The laminate is then placed in a frame-type sealing gasket mold and molded for curing at 180°C, 7 MPa, and a holding time of 12 minutes, while simultaneously molding the flange sealing rib. During molding, the microporous PTFE layer is pre-laid onto the top surface and inner wall of the sealing rib molding cavity, ensuring continuous coverage of the top and inner surfaces of the flange sealing rib during molding and conformal curing to the shape, resulting in... Figure 1 The structure shown.

[0101] Comparison test (example recorded values):

[0102] The setup for the comparative example was the same as that for Example 1. The test conditions were the same: 80°C, 30% KOH, 168 hours, and fixed clamping stress. Exemplary recorded values ​​are shown in Table 2-1.

[0103] Comparison Test Records (Example 2; Exemplary Record Values) Table 2-1

[0104]

[0105] Example 3 (Upper Value):

[0106] This embodiment provides a composite sealing material for an electrolytic cell. Unlike embodiments 1 and 2, this embodiment uses the upper end of the key range parameters to obtain a larger in-pore embedding area, a more pronounced gradient enrichment area, and a stronger orientation structure.

[0107] Raw materials and pretreatment:

[0108] The microporous polytetrafluoroethylene layer is made of expanded polytetrafluoroethylene film with an average pore size of 5 micrometers (top value) and a film thickness of 100 micrometers. It is cleaned with ethanol / deionized water and dried at 60°C as described above.

[0109] The sheet boron nitride is still used and a fluorosilane treatment layer is formed. In order to enhance the compatibility between the filler and the elastomer phase in the high-porosity system, the mass fraction of the fluorosilane coupling agent is adjusted to 1.0%, and the drying conditions after treatment are set to 110°C and 3 hours to ensure the stability of the surface treatment layer.

[0110] The layered ion capture filler still uses a compound of layered double hydroxide and fluorinated anion exchange resin to form composite particles, and then treats them with fluorinated organosilicon to form a surface treatment layer; in order to improve the construction stability of the enrichment layer, the particle size of the composite particles is controlled in the range of 100 to 300 micrometers.

[0111] The elastomer phase employs a dynamically vulcanized biphase structure composed of ethylene propylene rubber and fluorosilicone rubber. In this embodiment, the upper value is used, with the fluorosilicone rubber phase having a volume fraction of 45%, wherein the ethylene propylene rubber phase is the continuous phase and the fluorosilicone rubber phase is the dispersed phase. The material selection for the reactive ion-pair crosslinking system and the peroxide crosslinking system is consistent with the aforementioned.

[0112] Plasma surface activation (upper end value):

[0113] The microporous polytetrafluoroethylene layer was subjected to plasma surface activation treatment using a mixture of argon and oxygen (90% argon, 10% oxygen, total flow rate of 200 standard milliliters per minute). The treatment power was 800 watts and the treatment time was 180 seconds. The activated surface was formed and immediately entered the sol-gel coating process.

[0114] In-situ formation of fluorinated siloxane network layer and formation of embedded regions within pores (top value: penetration depth):

[0115] The precursor sol was prepared using an ethanol / water volume ratio of 90 / 10, a pH of approximately 5, a fluoroalkyltrialkoxysilane to epoxytrialkoxysilane molar ratio of 1 / 1, and hydrolysis prepolymerization for 30 minutes; the vinylsilane to silanol equivalent ratio was 1 / 1, and the platinum addition catalyst was controlled at the 10 ppm level. To accommodate larger pore sizes and achieve deeper penetration, the wet film thickness of the blade coating was controlled to approximately 30 micrometers in this embodiment.

[0116] After application, negative pressure assisted penetration was applied at a pressure of 0.08 MPa for 60 seconds to ensure the precursor sol fully penetrated the pores. Subsequently, the mixture was left at room temperature for 10 minutes and then heated at 80°C for 60 minutes to complete gelation and curing. This controlled the penetration depth of the fluorosiloxane network layer into the pores to 120 micrometers (top value), forming a continuous mechanically embedded zone within the pores. The penetration depth was confirmed by section microscopy / scanning electron microscopy.

[0117] Preparation of composite matrix layer compound, two-phase structure and composite crosslinking structure (top value ratio):

[0118] The composite matrix layer compounding process employs a two-stage mixing method. In the first stage, ethylene propylene rubber is plasticized and then blended with fluorosilicone rubber to achieve a fluorosilicone rubber phase volume fraction of 45%, along with flake boron nitride treated with fluorosilane; the sheeting temperature is controlled to not exceed 100°C. In the second stage, layered ion-trapping filler composite particles with a fluorinated organosilane-treated surface are added, along with quaternary ammonium salt-based polymers and sulfonate-based polymers to form a reactive ion-pair crosslinking system. Finally, a peroxide crosslinking system is added, and the sheeting temperature is controlled to not exceed 90°C, yielding the composite matrix layer compound. During the curing stage, a composite crosslinking structure is formed, consisting of both an ion-pair interaction network and a chemical crosslinking network.

[0119] Gradient enrichment region construction (upper value thickness):

[0120] In this embodiment, the gradient enrichment thickness at the upper end is set to 0.30 mm. The gradient is constructed using an enrichment film / matrix film overlay method: the compound of high-content layered ion-capturing filler composite particles is calendered into an enrichment film with a thickness of 0.30 mm; the compound of low-content layered ion-capturing filler composite particles is calendered into a matrix film and overlaid with the enrichment film; during overlay, the enrichment film is laid closer to the fluorosiloxane network layer, and the matrix film is laid further away from the fluorosiloxane network layer, creating a clear gradient distribution in the thickness direction of the composite matrix layer. (See diagram). Figure 1 .

[0121] Orientation of sheet-like boron nitride (orientation angle at the top):

[0122] The laminated composite matrix film is calendered and sheared for orientation at a roll temperature of 50–60°C and a roll gap of 1.5 mm, with 8 calendering passes. The orientation angle of the boron nitride flakes is controlled to 0° through stronger shearing, meaning that the boron nitride flakes tend to align more parallel to the in-plane direction of the material. After calendering, the film is cooled and shaped to maintain the orientation distribution.

[0123] The stacked molding process is integrated with the frame-type sealing gasket (molding parameters at the top):

[0124] A microporous polytetrafluoroethylene (PTFE) layer with a fluorinated siloxane network layer forming an embedded region is laminated with a composite matrix layer, with the enriched film positioned closer to the fluorinated siloxane network layer. The laminate is then placed into a frame-type sealing gasket mold and molded for curing at 200°C, 10 MPa, and for 20 minutes, while simultaneously molding a flange sealing rib. During molding, the microporous PTFE layer is extended and pre-laid onto the top surface and inner wall of the sealing rib molding cavity, ensuring continuous coverage of the top and inner surfaces of the flange sealing rib during molding and conforming to its shape for curing.

[0125] Comparison test (example recorded values):

[0126] The comparative example was set up in the same way as described above, with the same test conditions: 80°C, 30% KOH, 168 hours, and fixed clamping stress. Exemplary recorded values ​​are shown in Table 3-1.

[0127] Comparison Test Records (Example 3; Exemplary Record Values) Table 3-1

[0128]

[0129] This embodiment also provides a method for preparing an electrolytic cell composite sealing material, comprising: S1, providing a microporous polytetrafluoroethylene layer as a seepage barrier layer, and subjecting the seepage barrier layer to plasma surface activation to form an activated surface; S2, preparing a fluorinated siloxane network precursor sol, wherein the fluorinated siloxane network precursor sol comprises a fluorinated alkyltrialkoxysilane and an epoxytrialkoxysilane; S3, applying the fluorinated siloxane network precursor sol to the activated surface and performing hydrolysis and condensation to form an interface transition layer in situ on the surface of the seepage barrier layer, and during the formation process, allowing the interface transition layer to penetrate into the through-pores of the seepage barrier layer; S4, preparing a composite matrix layer compound, wherein the composite matrix layer compound comprises at least an elastomer phase and a surface layer. The process involves: S5, preparing an enriched film near the interface transition layer and a base film away from the interface transition layer, wherein the mass fraction of the layered ion-trapping filler in the enriched film is higher than that in the base film; stacking the enriched film and the base film to form a composite base layer preform with a thickness gradient distribution, and stacking the composite base layer preform with the anti-seepage layer having the interface transition layer; S6, pressurizing and heating the stacked body to form a composite base layer that is cross-linked and cured to obtain the electrolytic cell composite sealing material.

[0130] For ease of description and explanation, this embodiment will describe in detail the preparation method of an electrolytic cell composite sealing material through Examples 4-6, and the prepared electrolytic cell composite sealing material is as follows: Figure 5 As shown, the details are as follows.

[0131] It should be noted that the penetration depth (unit: micrometer) will be explained in this embodiment to clarify its definition.

[0132] The penetration depth is defined as the maximum continuous penetration distance of the interface transition layer into the through hole along the axial direction of the through hole on the cross section in the thickness direction of the impermeable layer, and this maximum continuous penetration distance is taken as the penetration depth.

[0133] It should be noted that the measurement method will be explained in this embodiment to clarify its definition.

[0134] Measurement method: The thickness direction profile of the sample is obtained by cryosectioning or ion beam cutting, and the observation method is optical microscope or scanning electron microscope; no less than 5 through holes on the same sample are selected for measurement and the maximum value is recorded.

[0135] It should be noted that the orientation angle and orientation distribution criteria will be explained in this embodiment to clarify their definitions.

[0136] The orientation angle is defined as the angle between the normal of the sheet-like insulating and thermally conductive filler sheet and the thickness direction of the material on a cross-section along the thickness direction of the composite matrix layer.

[0137] Criterion: Randomly sample no less than 50 sheet-like insulating and thermally conductive filler particles from the cross-sectional microscopic image, statistically analyze their orientation angle distribution, and record the proportion of orientation angles entering a preset interval; when this proportion reaches a preset threshold, it is determined that an orientation distribution has been formed.

[0138] Process window for simultaneous addition reactions:

[0139] After adding vinyl silane and silane to the fluorinated siloxane network precursor sol, the platinum-based addition catalyst is set to 5-20 ppm (calculated as platinum); the curing temperature is set to 70-120℃ and the curing time is set to 20-90 minutes, so that the addition reaction of vinyl and silane and the hydrolysis condensation are carried out simultaneously in the curing stage.

[0140] Zoned material laying boundary:

[0141] The enriched film is located in the surface region near the interface transition layer, and the thickness of the enriched film is 0.01–0.30 mm; the matrix film constitutes the remaining thickness region; the mass fraction of the layered ion-capturing filler in the enriched film is higher than that in the matrix film, so as to form a gradient distribution in the thickness direction.

[0142] The positioning action of the sealing rib covering the mold:

[0143] During mold assembly, a positioning reference for the anti-seepage layer is set in the mold cavity, and the extended edge of the anti-seepage layer is pre-laid to the top surface and inner wall of the flange sealing rib forming cavity. Before mold closing, the extended edge of the anti-seepage layer is pre-positioned by pressing to prevent misalignment during mold closing, so that the anti-seepage layer continuously covers the top surface and inner surface of the flange sealing rib during the forming process.

[0144] It should be noted that some commonalities will be explained here:

[0145] Raw materials:

[0146] Impermeable layer: Microporous polytetrafluoroethylene layer (through-pore structure film), 100 micrometers thick;

[0147] Fluorinated siloxane network precursor sol raw materials: fluorinated alkyltrialkoxysilane, epoxytrialkoxysilane, vinylsilane, silanol, anhydrous ethanol, deionized water, glacial acetic acid, platinum addition catalyst;

[0148] Composite matrix layer compound raw materials: ethylene propylene rubber, fluorosilicone rubber; sheet-like boron nitride with a fluorosilane treatment layer on the surface; layered ion trapping filler (composite particle form) with a fluorinated organosilane treatment layer on the surface; quaternary ammonium salt grouped polymer, sulfonate grouped polymer; peroxide crosslinking system (crosslinking agent and co-crosslinking agent).

[0149] equipment:

[0150] Low-temperature plasma treatment equipment, negative pressure chamber, internal mixer / open mill, twin-roll calender, flat vulcanizing machine, frame-type sealing gasket mold (including flange sealing rib forming cavity).

[0151] Overview of key range value coverage (upper value / middle value / lower value):

[0152] Key range value coverage comparison table 1

[0153]

[0154] Table 1 illustrates that the three specific embodiments selected the lower, middle, and upper limits of the process parameter range, thus covering the value range of plasma surface activation conditions and interface transition layer penetration depth. Reading the table, it can be seen that: Embodiment 4 uses the lowest power / shortest time and corresponds to the lowest penetration depth; Embodiment 5 uses intermediate process conditions and corresponds to an intermediate penetration depth; and Embodiment 6 uses the highest power / longest time and corresponds to the highest penetration depth. This table illustrates the feasibility of each endpoint within the parameter range.

[0155] Example 4 (Lower value: 100 watts / 5 seconds; Penetration depth 5 micrometers):

[0156] The preparation process in this embodiment is as follows: Figure 2 As shown, it includes steps S1 to S6.

[0157] Step S1:

[0158] A microporous polytetrafluoroethylene (PTFE) layer is provided as an impermeable layer. The microporous PTFE layer is a thin film with a through-pore structure and a thickness of 100 micrometers. In this embodiment, a microporous PTFE layer with an average pore size of 0.05 micrometers is selected. The impermeable layer is wiped twice with anhydrous ethanol, then wiped once with deionized water, and dried under hot air circulation at 60°C for 30 minutes.

[0159] The dried impermeable layer is placed into a low-temperature plasma treatment chamber. The plasma working gas is a mixture of argon and oxygen, with argon comprising 90% of the volume and oxygen comprising 10% of the volume, and a total flow rate of 200 standard milliliters per minute. The treatment power is set to 100 watts and the treatment time to 5 seconds, so that an activated surface is formed on one side of the impermeable layer. After the treatment is completed, the layer is left to stand in a clean environment for no more than 10 minutes before proceeding to step S3.

[0160] Step S2:

[0161] Add anhydrous ethanol and deionized water to a container, making the volume ratio of ethanol to deionized water 90 / 10; add fluorinated alkyltrialkoxysilane and epoxytrialkoxysilane, making the molar ratio of the two 1 / 1; add glacial acetic acid to adjust the pH of the system to about 5 and stir for 30 minutes to complete the hydrolysis prepolymerization.

[0162] Vinylsilane and silane-hydrosilane were added to make the vinyl to silane equivalent ratio 1 / 1; a platinum addition catalyst was added to make the platinum content 10 ppm; stirring was continued for 10 minutes to obtain a fluorinated siloxane network precursor sol.

[0163] Step S3:

[0164] Fluorinated siloxane network precursor sol was coated onto the activated surface with a wet film thickness of 20 micrometers. Immediately after coating, the surface was placed in a negative pressure chamber, and a negative pressure of 0.02 MPa was applied and maintained for 10 seconds, allowing the interface transition layer to enter the through-pores of the impermeable layer during the formation process. After the negative pressure was released, the surface was left to stand at room temperature for 10 minutes, and then heated at 80°C for 30 minutes to complete the hydrolysis condensation and curing. During the curing stage, the addition reaction of vinyl groups and silane groups occurred simultaneously, thereby forming an interface transition layer in situ on the surface of the impermeable layer and penetrating into the through-pores to form an embedded structure within the pores.

[0165] Penetration depth is measured according to the "maximum continuous penetration distance" caliber: at least 5 through holes are selected for the same sample for measurement and the maximum value is recorded.

[0166] Step S4:

[0167] The composite matrix layer compound was prepared by a two-stage mixing process. The first stage involved adding 90 parts of ethylene propylene rubber to an internal mixer at a chamber temperature of 60°C and a rotor speed of 40 rpm for 2 minutes; then adding 10 parts of fluorosilicone rubber and continuing mixing for 3 minutes to form the elastomer phase; finally, adding 20 parts of flake boron nitride with a fluorosilane-treated surface and mixing for 5 minutes, controlling the sheet temperature to not exceed 90°C.

[0168] Second stage of mixing: Return to the internal mixer, add layered ion-trapping filler (composite particles) with a fluorinated organosilanes treated on the surface, and add 2 parts of quaternary ammonium salt grouped polymer and 2 parts of sulfonate grouped polymer and mix for 4 minutes; add 2 parts of peroxide crosslinking system and mix for 2 minutes, and control the sheeting temperature to not exceed 80℃ to obtain composite matrix layer compound.

[0169] Step S5:

[0170] Enrichment films and substrate films were prepared separately, with the mass fraction of layered ion-capturing filler in the enrichment film being higher than that in the substrate film. In this embodiment, the enrichment film contained 18 parts of layered ion-capturing filler, the substrate film contained 6 parts of layered ion-capturing filler, and the remaining components were the same as in step S4.

[0171] The enriched formulation rubber compound is calendered into an enriched film with a thickness controlled to no more than 0.01 mm, which serves as the surface layer area near the interface transition layer; the matrix formulation rubber compound is calendered into a matrix film to form the remaining thickness area.

[0172] The enriched film is laid on the side close to the interface transition layer, and the matrix film is laid on the side away from the interface transition layer. They are then stacked to form a composite matrix layer preform with a thickness gradient distribution. The composite matrix layer preform is then stacked with the impermeable layer with the interface transition layer, with the interface transition layer facing the enriched film side and bonded together.

[0173] Step S6:

[0174] Before cross-linking and curing, the sheet-like insulating thermally conductive filler is oriented. The orientation process includes calendering and shearing orientation: roll temperature 50-60℃, roll gap 2.0 mm, calendering 3 times; after calendering, it is cooled to below 40℃ for cooling and shaping to maintain the orientation distribution, and no less than 50 particles are sampled according to the definition of orientation angle to form a statistical record.

[0175] The composite material is installed into a frame-type sealing gasket mold. During mold installation, the edge of the anti-seepage layer is pre-laid to the top surface and inner wall of the flange sealing rib forming cavity according to the mold cavity positioning reference, and the edge is pre-positioned before mold closing. The composite matrix layer is cross-linked, cured and shaped by molding at a molding temperature of 160℃, a pressure of 3MPa and a holding pressure of 5 minutes. At the same time, the flange sealing rib is integrally formed, and the anti-seepage layer continuously covers the top surface and inner surface of the flange sealing rib to obtain the electrolytic cell composite sealing material.

[0176] Example 5 (Intermediate values: 450 watts / 90 seconds; penetration depth 62.5 micrometers):

[0177] Step S1:

[0178] A microporous polytetrafluoroethylene layer with a thickness of 100 micrometers is provided as an impermeable layer. In this embodiment, a microporous polytetrafluoroethylene layer with an average pore size of 2.5 micrometers is selected. The cleaning and drying method is the same as in Example 4.

[0179] The plasma working gas is a mixture of argon and oxygen (90% argon, 10% oxygen, total flow rate 200 standard milliliters per minute); the processing power is set to 450 watts and the processing time is 90 seconds to form an activated surface; after processing, the surface is left to stand for no more than 10 minutes before proceeding to step S3.

[0180] Step S2:

[0181] Ethanol / water volume ratio 90 / 10; fluorinated alkyltrialkoxysilane to epoxytrialkoxysilane molar ratio 1 / 1; prepolymerize by hydrolysis at pH 5 for 30 minutes; add vinylsilane and silanolsilane to make the equivalent ratio 1 / 1; add platinum-based addition catalyst to make the platinum content 10 ppm; stir for 10 minutes to obtain fluorinated siloxane network precursor sol.

[0182] Step S3:

[0183] Apply a wet film thickness of 25 micrometers; after application, apply a negative pressure of 0.05 MPa and maintain it for 40 seconds; after releasing the negative pressure, let it stand at room temperature for 10 minutes, then place it at 80℃ and heat for 45 minutes to complete hydrolysis, condensation, and curing, and simultaneously undergo an addition reaction; measure no less than 5 through holes according to the penetration depth measurement diameter and record the maximum value, so that the penetration depth reaches 62.5 micrometers.

[0184] Step S4:

[0185] First stage of mixing: 72.5 parts of ethylene propylene rubber and 27.5 parts of fluorosilicone rubber, chamber temperature 60℃, rotation speed 40 rpm, plasticize for 2 minutes and then mix for 3 minutes; add 30 parts of flake boron nitride and mix for 5 minutes, with the sheeting temperature not exceeding 95℃.

[0186] Second stage of mixing: Add layered ion-capturing filler (composite particles) and 3 parts of quaternary ammonium salt grouped polymer and 3 parts of sulfonate grouped polymer and mix for 4 minutes; add 2 parts of peroxide crosslinking system and mix for 2 minutes. The sheeting temperature does not exceed 85℃ to obtain composite matrix layer compound.

[0187] Step S5:

[0188] 18 parts of enriched film layered ion capture filler and 6 parts of matrix film layered ion capture filler are used, and the remaining components are the same as in step S4. The enriched formulation is calendered into an enriched film with a thickness of 0.15 mm as the surface area near the interface transition layer. The matrix film constitutes the remaining thickness area. The materials are laid in sections and stacked to form a gradient preform and stacked with the impermeable layer with the interface transition layer. The interface transition layer faces the enriched film side and is bonded together.

[0189] Step S6:

[0190] Calendering and shearing orientation: roll temperature 50-60℃, roll gap 1.8 mm, calendering 5 passes; cooling and shaping, and sampling and statistically recording no less than 50 particles according to the orientation angle definition.

[0191] During molding, the edge of the seepage-proof layer is pre-laid to the top surface and inner wall of the sealing rib forming cavity according to the positioning reference and the edge is pressed and pre-positioned; the molding temperature is 180℃, the pressure is 7MPa, and the pressure is held for 12 minutes to cure and form the sealing rib, thus completing the integral molding of the sealing rib and making the seepage-proof layer continuously cover the top surface and inner side of the sealing rib.

[0192] Example 6 (Top value: 800 watts / 180 seconds; Penetration depth 120 micrometers):

[0193] Step S1:

[0194] A microporous polytetrafluoroethylene layer with a thickness of 100 micrometers is provided as an impermeable layer. In this embodiment, a microporous polytetrafluoroethylene layer with an average pore size of 5 micrometers is selected. The cleaning and drying method is the same as in Example 4.

[0195] The plasma working gas is a mixture of argon and oxygen (90% argon, 10% oxygen, total flow rate 200 standard milliliters per minute); the processing power is set to 800 watts and the processing time is set to 180 seconds to form an activated surface; after processing, the process immediately proceeds to step S3.

[0196] Step S2:

[0197] Ethanol / water volume ratio 90 / 10; fluorinated alkyltrialkoxysilane to epoxytrialkoxysilane molar ratio 1 / 1; prepolymerize by hydrolysis at pH 5 for 30 minutes; add vinylsilane and silanolsilane to make the equivalent ratio 1 / 1; add platinum-based addition catalyst to make the platinum content 10 ppm; stir for 10 minutes to obtain fluorinated siloxane network precursor sol.

[0198] Step S3:

[0199] Apply a wet film with a thickness of 30 micrometers; after application, apply a negative pressure of 0.08 MPa and maintain it for 60 seconds; after releasing the negative pressure, let it stand at room temperature for 10 minutes, then place it at 80℃ and heat for 60 minutes to complete the hydrolysis condensation curing and simultaneously undergo an addition reaction; measure no less than 5 through holes according to the penetration depth measurement diameter and record the maximum value, so that the penetration depth reaches 120 micrometers.

[0200] Step S4:

[0201] First stage of mixing: 55 parts of ethylene propylene rubber and 45 parts of fluorosilicone rubber, chamber temperature 60℃, rotation speed 40 rpm, plasticize for 2 minutes and then mix for 3 minutes; add 35 parts of flake boron nitride and mix for 5 minutes, with the sheeting temperature not exceeding 100℃.

[0202] Second stage of mixing: Add layered ion-capturing filler (composite particles) and 3 parts of quaternary ammonium salt grouped polymer and 3 parts of sulfonate grouped polymer and mix for 4 minutes; add 2 parts of peroxide crosslinking system and mix for 2 minutes. The sheeting temperature does not exceed 90℃ to obtain composite matrix layer compound.

[0203] Step S5:

[0204] 18 parts of enriched film layered ion capture filler and 6 parts of matrix film layered ion capture filler are used, and the remaining components are the same as in step S4. The enriched formulation is calendered into an enriched film with a thickness of 0.30 mm as the surface area near the interface transition layer. The matrix film constitutes the remaining thickness area. The materials are laid in sections and stacked to form a gradient preform and stacked with the impermeable layer with the interface transition layer. The interface transition layer faces the enriched film side and is bonded together.

[0205] Step S6:

[0206] Calendering and shearing orientation: roll temperature 50-60℃, roll gap 1.5 mm, calendering 8 passes; cooling and shaping, and sampling and statistically recording no less than 50 particles according to the orientation angle definition.

[0207] During molding, the edge of the seepage-proof layer is pre-laid to the top surface and inner wall of the sealing rib forming cavity according to the positioning reference and the edge is pressed and pre-positioned; the molding temperature is 200℃, the pressure is 10MPa, and the pressure is held for 20 minutes to cure and form the sealing rib, thus completing the integral molding of the sealing rib and making the seepage-proof layer continuously cover the top surface and inner side of the sealing rib.

[0208] Comparative Examples (Overall Comparison):

[0209] No plasma surface activation is performed, no fluorinated siloxane network precursor sol is prepared, no interface transition layer or pore embedded structure is formed; the enriched film and the matrix film are not distinguished in the composite matrix layer, no thickness gradient structure is formed, and no calendering shearing orientation and cooling shaping are performed; during molding, no anti-seepage layer extension pre-laying and edge pre-positioning control are implemented, and molding is performed according to the conventional laying method.

[0210] Comparative Example A (only lacking the negative pressure inlet):

[0211] Prepared according to the conditions of Example 5, but without applying negative pressure in step S3, while the remaining application and curing conditions remain unchanged.

[0212] Comparative Example B (only lacking gradient structure):

[0213] Prepared according to the conditions of Example 5, but in step S5, enrichment film and base film are not prepared, and partitioned layering is not performed. Instead, layered ion capture filler is uniformly distributed in the same film.

[0214] Comparative Example C (only orientation and shaping are missing):

[0215] Prepared according to the conditions of Example 5, but without calendering, shearing orientation, and cooling and shaping before crosslinking and curing.

[0216] Comparative Example D (only lacking sealing rib covering mold control):

[0217] Prepared according to the conditions of Example 5, but during molding, the impermeable layer is not extended and pre-laid to the top surface and inner wall of the sealing rib forming cavity, nor is edge pressing and pre-positioning performed.

[0218] Process Record Checklist P-1

[0219]

[0220] Table P-1 lists the key process parameters that should be recorded during the preparation process, including plasma treatment, sol preparation, coating and curing, negative pressure assistance, mixing, calendering and orientation, cooling and shaping, zoned layering and stacking, and molding and curing. The purpose of this table is to standardize the key points of the "feasible" process records, facilitating reproducibility and batch consistency management.

[0221] Comparison table and results data:

[0222] Comparison of process parameters and key features:

[0223] Comparison of process parameters (Comparison of Examples 1-3, Overall Comparison, and Detailed Comparison of Examples) Table 2

[0224]

[0225] Table 2 compares the differences in key process steps among different samples, including plasma activation conditions, negative pressure entry conditions, enrichment film thickness settings, whether orientation and cooling shaping were performed, and whether sealing rib coverage control was implemented. The purpose of this table is to record "what each sample did / did not do" in a checklist format, providing a correspondence for subsequent structural observation records (Tables 4 and T-1) and performance data (Tables 5-1, 5-2, and 5-3), facilitating the tracing of structural and performance differences from process variations.

[0226] Key Feature Missing Comparison (Example 2 and Comparisons A to D) Table C-1

[0227]

[0228] Table C-1 is used to clearly identify which key process feature is missing in each of the comparison samples A to D, thereby breaking down the overall scheme into comparable combinations of factors:

[0229] Comparison A: Missing negative pressure inlet port;

[0230] Comparison B: Lacks gradient structure;

[0231] Comparison C: Missing orientation and cooling / setting;

[0232] Comparison D: Missing sealing rib coverage control.

[0233] The purpose of this table is to provide a clear indication of "single-factor missing" in the comparative design, making it easier to compare and analyze in the results table.

[0234] Process quality control results:

[0235] Comparison Table 4 of Process Quality Control

[0236]

[0237] Table 4 records process / structure consistency indicators related to structure formation during the preparation process. The main meanings are as follows:

[0238] Activated surface presence: used to characterize whether plasma surface activation has occurred (examples are represented by contact angle, but surface energy can also be used in practice).

[0239] Penetration depth: Used to quantify the extent to which the interface transition layer penetrates the through-hole, measured according to the "maximum continuous penetration distance" caliber.

[0240] Interface transition layer continuity: Used to confirm whether the interface transition layer continuously covers the surface of the impermeable layer.

[0241] Gradient layer thickness / difference between enriched and distant sides: used to confirm whether a gradient structure in the thickness direction has formed and whether there is a difference in the degree of enrichment.

[0242] Orientation distribution retention: Used to confirm whether the calendering shear orientation and cooling shaping can still be maintained after curing.

[0243] Sealing reinforcement coverage integrity: Used to confirm whether the waterproof layer achieves continuous coverage of the top and inner surfaces in the sealing reinforcement area.

[0244] The purpose of this table is to solidify the "process-structure" link into record items, serving as support for feasibility and consistency documentation.

[0245] Penetration depth and orientation statistics:

[0246] Table T-1 Statistical Record of Penetration Depth and Orientation

[0247]

[0248] Table T-1 lists the two types of indicators that "require statistical definition" in the form of raw records:

[0249] 1) Multi-pore measurement record of penetration depth: The penetration depth of the same sample is measured in multiple through-holes and the maximum value is recorded to reflect the consistency between the measurement aperture and the sample structure.

[0250] 2) Orientation Angle Statistical Results: The sampling quantity and the proportion of orientation angles entering the preset interval are given to reflect the statistical results of the formation and maintenance of orientation distribution.

[0251] The purpose of this table is to provide a "traceable measurement basis" to avoid providing only a single value without a statistical source.

[0252] Leakage and potassium ion migration over time (see curves) Figure 3 and Figure 4 ):

[0253] Table 5-1 Cumulative Leakage (mL)

[0254]

[0255] Table 5-1 is used to record the cumulative leakage of the sample at different time points under the set immersion conditions and fixed clamping conditions, and is used to plot the data. Figure 3 The table shows the "cumulative leakage - time" curve. Key points for reading the table are: the cumulative leakage of different samples at the same time point can be directly compared; the cumulative leakage of the same sample at different time points can be used to observe the growth trend over time. This table is used to illustrate the change in sealing performance with immersion time.

[0256] Table 5-2 Potassium ion concentration (mg / L) of the outer collection solution

[0257]

[0258] Table 5-2 records the potassium ion concentration of the outer collected solution at different time points under set soaking conditions, and is used to plot... Figure 4 The table shows a "potassium ion mass concentration-time" curve. Key points for reading the table are: the change in potassium ion mass concentration over time reflects trends related to ion migration / osmosis; concentrations of different samples at the same time point can be directly compared. This table is used to illustrate the temporal evolution of ion migration-related indicators.

[0259] Other indicators:

[0260] Other recommended indicators are recorded in Table 5-3.

[0261]

[0262] Table 5-3 is used to supplement the recording of several optional indicators besides leakage amount and potassium ion mass concentration, including interfacial peel strength, compression set, and volume resistivity, which can be recorded before and after immersion. The purpose of this table is to provide supplementary observations from dimensions such as interfacial bonding, elasticity retention, and electrical properties, forming a more complete combination of evaluation dimensions, which facilitates multi-indicator comparison with control samples.

[0263] It should be noted that the cumulative leakage data at each time point in Table 5-1 can be obtained by connecting the data in chronological order. Figure 3 The cumulative leakage-time curve shown is obtained by connecting the potassium ion mass concentration data at each time point in Table 5-2 in chronological order. Figure 4 The curve is in the form of "potassium ion mass concentration - time". Figure 3 and Figure 4 Used to illustrate the curve representation, specific point data are based on Tables 5-1 and 5-2.

[0264] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An electrolytic cell composite sealing material, characterized by, It includes a waterproof layer, a composite matrix layer, and an interface transition layer disposed between the waterproof layer and the composite matrix layer; The impermeable layer is a microporous polytetrafluoroethylene layer, which has a through-pore structure. The interface transition layer is a fluorinated siloxane network layer, which is formed by the hydrolysis and condensation of fluorinated alkyltrialkoxysilane and epoxytrialkoxysilane, and the fluorinated siloxane network layer penetrates into the through-pores of the microporous polytetrafluoroethylene layer to form a mechanically embedded structure. The composite matrix layer includes an elastomeric phase, sheet-like insulating and thermally conductive filler, and layered ion-trapping filler. The surface of the sheet-like insulating and thermally conductive filler has a fluorosilane treatment layer, and the surface of the layered ion-trapping filler has a fluorinated organosilane treatment layer. The layered ion-capturing filler is distributed in a thickness gradient in the composite matrix layer, and the mass fraction of the layered ion-capturing filler is higher than the mass fraction in the remaining thickness range of the composite matrix layer within a thickness range of 0 to 0.30 mm, taking the surface of the composite matrix layer near the interface transition layer as the starting point.

2. The composite seal material for electrolytic cells according to claim 1, characterized in that, The average pore size of the microporous polytetrafluoroethylene layer is 0.05 to 5 micrometers, and the penetration depth of the fluorinated siloxane network layer into the microporous polytetrafluoroethylene layer is 5 to 120 micrometers.

3. The electrolytic cell composite sealing material of claim 1, wherein, The elastomer phase is a two-phase structure formed by dynamic vulcanization. The two-phase structure includes an ethylene propylene rubber phase and a fluorosilicone rubber phase, wherein the ethylene propylene rubber phase is a continuous phase, the fluorosilicone rubber phase is a dispersed phase, and the volume fraction of the fluorosilicone rubber phase is 10% to 45%.

4. The electrolytic cell composite sealing material of claim 1, wherein, The layered ion-capturing packing is a compound of layered double hydroxide and fluorinated anion exchange resin, and the layered double hydroxide and the fluorinated anion exchange resin exist in the form of composite particles within the thickness range of 0 to 0.30 mm.

5. The electrolytic cell composite sealing material of claim 1, wherein, The sheet-like insulating and thermally conductive filler is sheet-like boron nitride, and the sheet-like boron nitride is oriented within the composite matrix layer. The angle between the normal of the sheet-like boron nitride and the thickness direction of the electrolytic cell composite sealing material is 0 to 30 degrees.

6. The electrolytic cell composite sealing material of claim 1, wherein, The composite matrix layer further includes a reactive ion-pair crosslinking system, which includes a quaternary ammonium salt grouped polymer and a sulfonate grouped polymer, and the reactive ion-pair crosslinking system and the peroxide crosslinking system together constitute a composite crosslinking structure.

7. The electrolyzer composite sealing material of claim 1, wherein, The composite sealing material of the electrolytic cell is a frame-type sealing gasket. The frame-type sealing gasket is integrally formed with a flange sealing rib along the circumference. The flange sealing rib is formed by the composite matrix layer, and the anti-seepage layer continuously covers the top and inner surfaces of the flange sealing rib.

8. A method of producing a composite sealing material for an electrolytic cell as claimed in any one of claims 1 to 7, characterized in that, include: S1, a microporous polytetrafluoroethylene layer is provided as a seepage barrier layer, and the seepage barrier layer is subjected to plasma surface activation to form an activated surface; S2, prepare a fluorinated siloxane network precursor sol, wherein the fluorinated siloxane network precursor sol comprises fluorinated alkyltrialkoxysilane and epoxytrialkoxysilane. S3, the fluorinated siloxane network precursor sol is applied to the activated surface and hydrolyzed and condensed to form an interface transition layer in situ on the surface of the impermeable layer, and the interface transition layer penetrates into the through pores of the impermeable layer during the formation process. S4, prepare a composite matrix layer compound, wherein the composite matrix layer compound comprises at least an elastomer phase, a sheet-like insulating and thermally conductive filler with a fluorosilane treatment layer on the surface, and a layered ion-trapping filler with a fluorinated organosilane treatment layer on the surface. S5, prepare an enriched film near the interface transition layer and a matrix film away from the interface transition layer, wherein the mass fraction of the layered ion-capturing filler in the enriched film is higher than the mass fraction of the layered ion-capturing filler in the matrix film; stack the enriched film and the matrix film to form a composite matrix layer preform with a thickness gradient distribution, and stack the composite matrix layer preform with the impermeable layer having the interface transition layer; S6, the composite body is pressurized and heated to form a composite matrix layer and crosslinked and cured to obtain the electrolytic cell composite sealing material.

9. The production method according to claim 8, characterized by, The plasma surface activation in step S1 includes processing conditions of 100-800 watts power and 5-180 seconds processing time, and the working gas of the plasma includes a mixture of argon and oxygen.

10. The preparation method according to claim 8, characterized in that, The fluorinated siloxane network precursor sol in step S2 further comprises vinyl silane and silane, and in step S3, the addition reaction of vinyl and silane occurs simultaneously during the hydrolysis-condensation process.

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