Bulked polytetrafluoroethylene conductive sealing film

Abstract

The present application provides a kind of expanded polytetrafluoroethylene conductive sealing film, including expanded polytetrafluoroethylene film and carbon fiber conductive layer, and the expanded polytetrafluoroethylene film has porosity;Carbon fiber conductive layer and expanded polytetrafluoroethylene film are compounded together by rolling, and carbon fiber conductive layer includes mutually connected surface layer and filling part, surface layer is arranged on the surface of at least one side of expanded polytetrafluoroethylene film, and filling part is filled in the porosity of expanded polytetrafluoroethylene film;The composition of carbon fiber conductive layer includes carbon-based fiber material, conductive powder and binder, and carbon-based fiber material is carbon fiber and / or carbon whisker.The expanded polytetrafluoroethylene conductive sealing film provided by the present application not only has the advantages of light weight, high and low temperature resistance, good sealing performance, etc., but also has good conductivity, and the bonding force between carbon fiber conductive layer and expanded polytetrafluoroethylene film is strong, and carbon fiber conductive layer is not easy to fall off.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to an expanded polytetrafluoroethylene conductive sealing film. Background Technology

[0002] Expanded PTFE is made from polytetrafluoroethylene resin through special processing methods such as stretching. It has a network structure formed by interconnected microfibers, creating numerous tiny pores between these fibers. Expanded PTFE exhibits excellent chemical resistance, abrasion resistance, and extremely strong high / low temperature resistance. Furthermore, due to its numerous pores, it can be used in applications requiring high-temperature sealing and where weight is a constraint.

[0003] Because expanded polytetrafluoroethylene (ePTFE) has characteristics such as small pore size, high porosity, uniform pore size distribution, high strength, and low relative density, it can be used in some air-permeable but water-impermeable applications. For example, by combining ePTFE with conductive materials, ePTFE conductive materials can be obtained. These materials possess the advantages of ePTFE, such as air permeability, water impermeability, lightweight, resistance to high and low temperatures, and good sealing properties, while also exhibiting good conductivity.

[0004] However, current expanded PTFE conductive materials generally involve coating the surface of expanded PTFE with a conductive material (see patents such as CN107446156A for details), followed by drying to form a conductive layer on the PTFE surface. However, because the conductive layer is only located on the surface of the expanded PTFE, and because expanded PTFE itself has relatively low surface energy, it is difficult to composite with other materials (mainly because fluorine atoms in expanded PTFE are highly polar; when fluorine atoms combine with other elements, they almost completely lose electrons, forming a stable octet structure; therefore, it is difficult for other groups to generate van der Waals forces with them). This results in the conductive layer of this structure easily detaching from the surface of the expanded PTFE, thus affecting its normal use. Summary of the Invention

[0005] The purpose of this invention is to provide an expanded polytetrafluoroethylene conductive sealing film, which not only has the advantages of being lightweight, resistant to high and low temperatures, and having good sealing performance, but also has good conductivity. Moreover, the bonding force between the carbon fiber conductive layer and the expanded polytetrafluoroethylene film is strong, and the carbon fiber conductive layer is not easy to fall off.

[0006] This invention provides an expanded polytetrafluoroethylene (ePTFE) conductive sealing film, comprising an ePTFE film and a carbon fiber conductive layer, wherein the ePTFE film has pores; the carbon fiber conductive layer and the ePTFE film are bonded together by roll forming, the carbon fiber conductive layer comprising an interconnected surface layer and a filling portion, the surface layer being disposed on at least one side of the surface of the ePTFE film, and the filling portion filling the pores of the ePTFE film; the carbon fiber conductive layer comprises carbon-based fiber material, conductive powder, and binder, wherein the carbon-based fiber material is carbon fiber and / or carbon whiskers.

[0007] In one possible implementation, the surface layer is disposed on one side of the expanded polytetrafluoroethylene film; or, the surface layer is disposed on opposite sides of the expanded polytetrafluoroethylene film, and the opposite sides of the surface layer are connected by the filler portion.

[0008] In one feasible approach, the carbon fiber conductive layer has a porous structure.

[0009] In one possible implementation, the expanded polytetrafluoroethylene film undergoes a low-temperature plasma surface treatment before being bonded to the carbon fiber conductive layer to enhance the bonding strength between the expanded polytetrafluoroethylene film and the carbon fiber conductive layer.

[0010] In one feasible embodiment, the thickness of the surface layer is 15 μm to 1 mm, and the thickness of the expanded polytetrafluoroethylene film is 0.05 mm to 3 mm.

[0011] In one feasible manner, the conductive powder is one or more of graphite powder, carbon black powder, copper powder, silver powder, aluminum powder, silver-coated copper powder, and silver-coated aluminum powder.

[0012] In one feasible embodiment, the carbon-based fiber material, the conductive powder, and the binder are respectively in the following weight proportions: 35-50 parts of carbon-based fiber material, 35-45 parts of conductive powder, and 2-8 parts of binder; the carbon-based fiber material has a mesh size of 50-100 mesh.

[0013] In one feasible manner, the method for preparing the expanded polytetrafluoroethylene conductive sealing film includes the following steps:

[0014] S10: Take 35-50 parts of carbon-based fiber material, 35-45 parts of conductive powder and 2-8 parts of binder, mix and ball mill for a period of time to obtain the first composite material;

[0015] S20: Take 45-85 parts of the first composite material and 5-20 parts of solvent, put them into a mixer and stir them into a ball to obtain the second composite material; then put the second composite material into a rolling mill and mix it evenly.

[0016] S30: The second composite material is rolled and laminated with the expanded polytetrafluoroethylene film, so that the second composite material covers the surface of the expanded polytetrafluoroethylene film and fills the pores of the expanded polytetrafluoroethylene film to obtain the third composite material.

[0017] S40: The third composite material is dried to obtain the expanded polytetrafluoroethylene conductive sealing film; wherein, the second composite material is formed into the carbon fiber conductive layer after drying.

[0018] In one feasible embodiment, in step S20 above, the solvent is ethanol and / or propanol; and 5-25 parts of water are also added to the second composite material.

[0019] In step S40 above, drying the third composite material specifically includes: placing the third composite material at -18°C to -25°C for freeze-drying for 3-5 hours to evaporate the water and solvent in the second composite material, thereby forming a porous structure for the carbon fiber conductive layer.

[0020] In one possible implementation, in step S30 above, before rolling the second composite material with the expanded polytetrafluoroethylene film, the expanded polytetrafluoroethylene film is subjected to a low-temperature plasma surface treatment to enhance the bonding force between the expanded polytetrafluoroethylene film and the second composite material.

[0021] The expanded polytetrafluoroethylene (ePTFE) conductive sealing film provided by this invention is composed of a carbon fiber conductive layer and an ePTFE film. It not only possesses the advantages of ePTFE, such as its lightweight, high and low temperature resistance, and good sealing performance, but also exhibits excellent conductivity. Furthermore, because the carbon fiber conductive layer and the ePTFE film are bonded together through roll forming, during the rolling process, a portion of the carbon fiber conductive layer (i.e., the surface layer) bonds to the surface of the ePTFE film, while the other portion (i.e., the filling portion) fills the pores of the ePTFE film. This increases the bonding area between the carbon fiber conductive layer and the ePTFE film, greatly enhancing the bonding force between them. This makes it difficult for the carbon fiber conductive layer to separate from the ePTFE film, ensuring the structural stability and reliability of the ePTFE conductive sealing film.

[0022] Meanwhile, the carbon fiber conductive layer is composed of carbon-based fiber materials, conductive powder, and binder. The carbon-based fiber materials are carbon fibers and / or carbon whiskers. That is, the carbon fiber conductive layer uses carbon fibers and / or carbon whiskers with good conductivity and high structural strength as the matrix. The conductive powder can further enhance the conductivity of the carbon fiber conductive layer. The binder can bond the carbon-based fiber materials, conductive powder, and expanded polytetrafluoroethylene together, so that the carbon fiber conductive layer has good conductivity, structural strength, and toughness. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the expanded polytetrafluoroethylene conductive sealing film in an embodiment of the present invention.

[0024] Figure 2 for Figure 1 A cross-sectional schematic diagram.

[0025] Figure 3 for Figure 2 A schematic diagram of the cross-section of a medium-expanded polytetrafluoroethylene film.

[0026] Figure 4 This is a three-dimensional structural diagram of an expanded polytetrafluoroethylene conductive sealing film according to another embodiment of the present invention.

[0027] Figure 5 for Figure 4 A cross-sectional schematic diagram.

[0028] Figure 6 This is a cross-sectional schematic diagram of an expanded polytetrafluoroethylene conductive sealing film in another embodiment of the present invention. Detailed Implementation

[0029] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0030] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0031] The directional terms such as "up," "down," "left," "right," "front," "back," "top," and "bottom" (if present) used in the specification and claims of this invention are defined by the position of the structures in the drawings and the relative positions of the structures, and are only for the clarity and convenience of expressing the technical solution. It should be understood that the use of directional terms should not limit the scope of protection claimed by this invention.

[0032] like Figures 1 to 3As shown, the expanded polytetrafluoroethylene (ePTFE) conductive sealing film provided in this embodiment of the invention includes an ePTFE film 1 and a carbon fiber conductive layer 2. The ePTFE film 1 has pores 10 (the pores 10 are formed between the fibers in the ePTFE film 1; the pores 10 in the ePTFE film 1 can be made by special processing methods such as stretching polytetrafluoroethylene resin). The carbon fiber conductive layer 2 and the ePTFE film 1 are bonded together by roll forming. The carbon fiber conductive layer 2 includes an interconnected surface layer 21 and a filling portion 22. The surface layer 21 is disposed on the surface of at least one side of the ePTFE film 1, and the filling portion 22 fills the pores 10 of the ePTFE film 1. That is, both the surface layer 21 and the filling portion 22 of the carbon fiber conductive layer 2 are bonded together with the ePTFE film 1. The carbon fiber conductive layer 2 is composed of carbon-based fiber material, conductive powder, and binder. The carbon-based fiber material is carbon fiber and / or carbon whiskers.

[0033] The expanded polytetrafluoroethylene conductive sealing film provided in this embodiment is composed of a carbon fiber conductive layer 2 and an expanded polytetrafluoroethylene film 1. It not only has the advantages of expanded polytetrafluoroethylene such as being lightweight, resistant to high and low temperatures, and having good sealing properties, but also has good conductivity. Meanwhile, since the carbon fiber conductive layer 2 and the expanded polytetrafluoroethylene film 1 are bonded together by roll forming, during the roll forming process, a portion of the carbon fiber conductive layer 2 (i.e., the surface layer 21) is bonded to the surface of the expanded polytetrafluoroethylene film 1, while the other portion (i.e., the filling portion 22) is filled into the pores 10 of the expanded polytetrafluoroethylene film 1. This increases the bonding area between the carbon fiber conductive layer 2 and the expanded polytetrafluoroethylene film 1, greatly enhancing the bonding force between them. (Moreover, the filling portion 22 filling the pores 10 of the expanded polytetrafluoroethylene film 1 not only increases the bonding area between the carbon fiber conductive layer 2 and the expanded polytetrafluoroethylene film 1, i.e., increases the van der Waals force between them, but also gives them a mechanical bonding force, i.e., similar to the filling portion 22 being stuck in the pores 10, forming an interlocking structure, thereby greatly increasing the bonding force between them.) This makes it difficult for the carbon fiber conductive layer 2 to separate and fall off from the expanded polytetrafluoroethylene film 1, ensuring the structural stability and reliability of the expanded polytetrafluoroethylene conductive sealing film.

[0034] Meanwhile, the carbon fiber conductive layer 2 is composed of carbon-based fiber material, conductive powder, and binder. The carbon-based fiber material is carbon fiber and / or carbon whiskers. That is, the carbon fiber conductive layer 2 uses carbon fiber and / or carbon whiskers with good conductivity and high structural strength as the matrix (while graphene, carbon black, etc. do not have fiber structure, so their structural strength is relatively weak, and the structural strength and toughness of the conductive layer made from them are also relatively weak). The conductive powder can further enhance the conductivity of the carbon fiber conductive layer 2. The binder can bond the carbon-based fiber material, conductive powder, and expanded polytetrafluoroethylene together (that is, the binder can bond the components in the carbon fiber conductive layer 2 together, and can also bond the carbon fiber conductive layer 2 to the expanded polytetrafluoroethylene film 1), so that the carbon fiber conductive layer 2 has good conductivity, structural strength, and toughness (the carbon fiber conductive layer 2 will not crack during bending and use).

[0035] In one embodiment, all pores 10 of the expanded polytetrafluoroethylene film 1 are filled with a carbon fiber conductive layer 2, or only some pores 10 may be filled with the carbon fiber conductive layer 2. The filling depth of the filling portion 22 in the pores 10 can be determined according to actual needs (specifically, according to the roller pressure).

[0036] In one implementation, the carbon fiber conductive layer 2 has a porous structure, which makes the expanded polytetrafluoroethylene conductive sealing film also have a porous structure, thereby ensuring that the expanded polytetrafluoroethylene conductive sealing film has a certain degree of air permeability.

[0037] Specifically, since the filling portion 22 of the carbon fiber conductive layer 2 fills the pores 10 of the expanded polytetrafluoroethylene film 1, that is, the carbon fiber conductive layer 2 blocks the micropores of the expanded polytetrafluoroethylene film 1, it will affect the air permeability of the expanded polytetrafluoroethylene film 1. Therefore, in this embodiment, the carbon fiber conductive layer 2 is set as a porous structure, thereby ensuring that the expanded polytetrafluoroethylene conductive sealing film has a certain degree of air permeability. Of course, in other embodiments, when the expanded polytetrafluoroethylene conductive sealing film does not need to have air permeability, the carbon fiber conductive layer 2 can also be a dense non-porous structure.

[0038] In one embodiment, the raw materials for preparing the carbon fiber conductive layer 2 also include solvents and / or water, and the solvent can be an organic solvent such as ethanol and / or propanol. During manufacturing, the carbon fiber conductive layer 2 is formed by mixing carbon-based fiber materials, conductive powder, binder, solvent and / or water, and then laminating it with an expanded polytetrafluoroethylene film 1 via roll forming, followed by freeze-drying. Because there are pores between the fibers in the carbon fiber conductive layer 2, during freeze-drying, the solvent and / or water evaporate (when only an aqueous solvent is used), forming a porous structure in the carbon fiber conductive layer 2. Simultaneously, the low-temperature freeze-drying prevents oxidation of the carbon fiber conductive layer 2. Of course, in other embodiments, when the expanded polytetrafluoroethylene conductive sealing film does not require air permeability, other drying methods can be used for the carbon fiber conductive layer 2 to avoid forming a porous structure or to reduce the number of pores formed in the carbon fiber conductive layer 2.

[0039] Specifically, freeze-drying, also known as sublimation drying, is a drying method that involves freezing water-containing materials below their freezing point, causing the water to transform into ice, and then removing the ice by converting it into vapor under a high vacuum. Freeze-drying utilizes the principle of ice crystal sublimation. Under a high vacuum environment, the water in the frozen material is directly sublimated from solid ice into vapor without the melting of the ice. Therefore, during the freeze-drying process, due to the evaporation of solvents and / or water, a porous structure is formed in the carbon fiber conductive layer 2.

[0040] As one implementation method, the expanded polytetrafluoroethylene film 1 undergoes low-temperature plasma surface treatment before being bonded to the carbon fiber conductive layer 2 to enhance the polarity of the surface of the expanded polytetrafluoroethylene film 1, thereby enhancing the bonding force between the expanded polytetrafluoroethylene film 1 and the carbon fiber conductive layer 2.

[0041] like Figure 1 and Figure 2 As shown, in one embodiment, along the thickness direction T of the expanded polytetrafluoroethylene conductive sealing film, the surface layer 21 of the carbon fiber conductive layer 2 is disposed on the surface of one side of the expanded polytetrafluoroethylene film 1, so that the expanded polytetrafluoroethylene conductive sealing film forms a structure in which one side is conductive and the other side is non-conductive.

[0042] like Figure 4 and Figure 5As shown, in another embodiment, along the thickness direction T of the expanded polytetrafluoroethylene conductive sealing film, the surface layer 21 of the carbon fiber conductive layer 2 is disposed on the surfaces of opposite sides of the expanded polytetrafluoroethylene film 1. The filling portion 22 penetrates the pores 10 of the expanded polytetrafluoroethylene film 1, and the surface layers 21 on opposite sides are connected by the filling portion 22 (that is, the two ends of the filling portion 22 are respectively connected to the surface layers 21 on opposite sides), so that the surface layers 21 on opposite sides can be electrically and mechanically connected to each other, so that the expanded polytetrafluoroethylene conductive sealing film forms a structure that is conductive on both sides and open on both sides, further improving the conductivity of the expanded polytetrafluoroethylene conductive sealing film and the bonding force between the carbon fiber conductive layer 2 and the expanded polytetrafluoroethylene film 1.

[0043] Of course, such as Figure 6 As shown, in other embodiments, depending on the required function, the filling part 22 can also be a disconnected structure; along the thickness direction T of the expanded polytetrafluoroethylene conductive sealing film, the filling part 22 includes a first part (not labeled) and a second part (not labeled). The first part is connected to one side of the surface layer 21, and the second part is connected to the other side of the surface layer 21. The first part and the second part are spaced apart from each other (i.e., they are not connected together). That is, the surface layers 21 on opposite sides are not electrically connected, so that the expanded polytetrafluoroethylene conductive sealing film forms a structure that is conductive on both sides and non-conductive on both sides (the surface layers 21 on both sides can be connected to different circuits to achieve different functional requirements).

[0044] In one embodiment, the thickness of the surface layer 21 is 15 μm to 1 mm, and the thickness of the expanded polytetrafluoroethylene film 1 is 0.05 mm to 3 mm, so that the expanded polytetrafluoroethylene conductive sealing film has good structural strength and conductivity.

[0045] In one embodiment, the expanded polytetrafluoroethylene film 1 has a porosity of 50% to 80%, and the average pore size of the pores 10 is 1 μm to 10 μm.

[0046] In one embodiment, the conductive powder is one or more of graphite powder, carbon black powder, copper powder, silver powder, aluminum powder, silver-coated copper powder, and silver-coated aluminum powder. The binder is CMC (carboxymethyl cellulose).

[0047] In one embodiment, the weight parts of carbon-based fiber material, conductive powder, and binder are as follows: 35-50 parts of carbon-based fiber material, 35-45 parts of conductive powder, and 2-8 parts of binder; the mesh size of the carbon-based fiber material is 50-100 mesh.

[0048] As one implementation method, the preparation method of expanded polytetrafluoroethylene conductive sealing film includes the following steps:

[0049] S10: Take 35-50 parts of carbon-based fiber material, 35-45 parts of conductive powder and 2-8 parts of binder, mix and ball mill for a period of time (e.g., 1-3 hours) to obtain the first composite material;

[0050] S20: Take 45-85 parts of the first composite material and 5-20 parts of solvent, put them into a mixer and stir them into a ball to obtain the second composite material; then put the second composite material into a roller press and mix it evenly (during mixing, the rolling speed of the roller press can be controlled at 5r / min to 8r / min, and after rolling 2 to 3 times, take it out to further mix the second composite material evenly and improve the strength and toughness of the second composite material).

[0051] S30: The second composite material is rolled together with the expanded polytetrafluoroethylene (ePTFE) film 1, so that the second composite material covers the surface of the ePTFE film 1 and fills the pores 10 of the ePTFE film 1, to obtain the third composite material (specifically, during the roll forming process, the gap between the rollers in the roll forming equipment can be adjusted according to the required thickness, and then the second composite material and the ePTFE film 1 are fed into the roller gap for roll forming, controlling the roller speed to be 3r / min~10r / min; this roll forming process is at room temperature. During the roll forming process, after the second composite material is subjected to the squeezing force of the roller, part of it adheres to the surface of the ePTFE film 1, and the other part fills the pores 10 of the ePTFE film 1); after the roll forming is completed, the third composite material is peeled off from the roller;

[0052] S40: The third composite material is dried to obtain an expanded polytetrafluoroethylene conductive sealing film; wherein, the second composite material is formed into a carbon fiber conductive layer 2 after drying.

[0053] In one embodiment, in step S20 above, the solvent is ethanol and / or propanol; 5-25 parts of water are also added to the second composite material; (the purpose of adding water is, on the one hand, to adjust the viscosity of the second composite material, and on the other hand, because water and solvent molecules are of different sizes, they can form pores of different sizes in the carbon fiber conductive layer 2 after evaporation).

[0054] In step S40 above, drying the third composite material specifically includes: placing the third composite material at -18°C to -25°C for freeze-drying for 3-5 hours to evaporate the water and solvent in the second composite material, thereby forming the carbon fiber conductive layer 2 into a porous structure.

[0055] Of course, in other embodiments, if the expanded polytetrafluoroethylene conductive sealing film is not required to be breathable, other drying methods can be used on the carbon fiber conductive layer 2 to avoid forming a porous structure in the carbon fiber conductive layer 2, or to reduce the number of pores formed in the carbon fiber conductive layer 2.

[0056] As one implementation method, in step S30 above, before rolling the second composite material with the expanded polytetrafluoroethylene film 1, the expanded polytetrafluoroethylene film 1 is subjected to low-temperature plasma surface treatment to enhance the bonding force between the expanded polytetrafluoroethylene film 1 and the second composite material. The specific steps of the low-temperature plasma surface treatment are as follows: the expanded polytetrafluoroethylene film 1 is placed in the plasma treatment chamber of a low-temperature plasma machine; the plasma treatment chamber is evacuated, and the vacuum degree is adjusted to 6–10 Pa; then, a gas (argon, oxygen, nitrogen, etc.) is introduced into the plasma treatment chamber for plasmaization; when the vacuum degree is adjusted to 65–85 Pa, the frequency is controlled at 10–25 MHz, and the treatment time is 25–60 seconds.

[0057] In one embodiment, when the surface layer 21 of the carbon fiber conductive layer 2 is disposed on the surface of one side of the expanded polytetrafluoroethylene film 1, it can be rolled only once (of course, it can also be rolled multiple times); when the surface layer 21 of the carbon fiber conductive layer 2 is disposed on the surfaces of opposite sides of the expanded polytetrafluoroethylene film 1, the surface layers 21 on both sides can be formed by one rolling, or the surface layers 21 on both sides can be formed by two rolling processes (of course, it can also be rolled more times).

[0058] The expanded polytetrafluoroethylene conductive sealing film provided in this embodiment of the invention is composed of a carbon fiber conductive layer 2 and an expanded polytetrafluoroethylene film 1. It not only has the advantages of expanded polytetrafluoroethylene such as being lightweight, resistant to high and low temperatures, and having good sealing properties, but also has good conductivity. Meanwhile, since the carbon fiber conductive layer 2 and the expanded polytetrafluoroethylene film 1 are bonded together by roll forming, during the roll forming process, a portion of the carbon fiber conductive layer 2 (i.e., the surface layer 21) is bonded to the surface of the expanded polytetrafluoroethylene film 1, while the other portion (i.e., the filling portion 22) is filled into the pores 10 of the expanded polytetrafluoroethylene film 1. This increases the bonding area between the carbon fiber conductive layer 2 and the expanded polytetrafluoroethylene film 1, greatly enhancing the bonding force between them. (Moreover, the filling portion 22 filling the pores 10 of the expanded polytetrafluoroethylene film 1 not only increases the bonding area between the carbon fiber conductive layer 2 and the expanded polytetrafluoroethylene film 1, i.e., increases the van der Waals force between them, but also gives them a mechanical bonding force, i.e., similar to the filling portion 22 being stuck in the pores 10, forming an interlocking structure, thereby greatly increasing the bonding force between them.) This makes it difficult for the carbon fiber conductive layer 2 to separate and fall off from the expanded polytetrafluoroethylene film 1, ensuring the structural stability and reliability of the expanded polytetrafluoroethylene conductive sealing film.

[0059] Meanwhile, the carbon fiber conductive layer 2 is composed of carbon-based fiber material, conductive powder, and binder. The carbon-based fiber material is carbon fiber and / or carbon whiskers, meaning that the carbon fiber conductive layer 2 uses carbon fiber and / or carbon whiskers with good conductivity and high structural strength as the matrix. The conductive powder further enhances the conductivity of the carbon fiber conductive layer 2, and the binder can bond the carbon-based fiber material, conductive powder, and expanded polytetrafluoroethylene (e.g., the binder can bond the components in the carbon fiber conductive layer 2 together, and also bond the carbon fiber conductive layer 2 to the expanded polytetrafluoroethylene film 1), giving the carbon fiber conductive layer 2 good conductivity, structural strength, and toughness. The carbon fiber conductive layer 2 uses carbon-based fiber material as a support. After being agglomerated with the binder and conductive powder, it is rolled and laminated with the expanded polytetrafluoroethylene film 1, and then dried to obtain an integrated composite conductive material. The manufacturing method is simple and can be mass-produced. This expanded polytetrafluoroethylene conductive sealing film can be used as a sealing sleeve requiring electrical connection (e.g., in aircraft cabin doors where electrical connection is required).

[0060] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An expanded polytetrafluoroethylene conductive sealing film, characterized in that, The material includes an expanded polytetrafluoroethylene (ePTFE) film and a carbon fiber conductive layer. The ePTFE film has pores. The carbon fiber conductive layer and the ePTFE film are bonded together by roll forming. The carbon fiber conductive layer includes interconnected surface layers and filler portions. The surface layers are disposed on opposite sides of the ePTFE film, and the filler portions fill the pores of the ePTFE film. The opposite surface layers are connected to each other through the filler portions. The carbon fiber conductive layer has a porous structure. The preparation method of the expanded polytetrafluoroethylene conductive sealing film includes the following steps: S10: By weight, take 35-50 parts of carbon-based fiber material, 35-45 parts of conductive powder and 2-8 parts of binder, mix and ball mill for a period of time to obtain the first composite material; the carbon-based fiber material is carbon fiber and / or carbon whiskers. S20: By weight, take 45-85 parts of the first composite material, 5-20 parts of solvent and 5-25 parts of water, put them into a mixer and stir them into a ball to obtain the second composite material; then put the second composite material into a roller press and mix it evenly; wherein, the solvent is ethanol and / or propanol; S30: The second composite material is rolled and laminated with the expanded polytetrafluoroethylene film, so that the second composite material covers the surface of the expanded polytetrafluoroethylene film and fills the pores of the expanded polytetrafluoroethylene film to obtain the third composite material. S40: The third composite material is dried to obtain the expanded polytetrafluoroethylene conductive sealing film; wherein, the second composite material is formed into the carbon fiber conductive layer after drying; The drying of the third composite material specifically includes: placing the third composite material at -18°C to -25°C for freeze-drying for 3-5 hours to evaporate the water and solvent in the second composite material, thereby forming a porous structure in the carbon fiber conductive layer.

2. The expanded polytetrafluoroethylene conductive sealing film as described in claim 1, characterized in that, The thickness of the surface layer is 15μm to 1mm, and the thickness of the expanded polytetrafluoroethylene film is 0.05mm to 3mm.

3. The expanded polytetrafluoroethylene conductive sealing film as described in claim 1, characterized in that, The conductive powder is one or more of the following: graphite powder, carbon black powder, copper powder, silver powder, aluminum powder, silver-coated copper powder, and silver-coated aluminum powder.

4. The expanded polytetrafluoroethylene conductive sealing film as described in claim 1, characterized in that, The carbon-based fiber material has a mesh size of 50-100 mesh.

5. The expanded polytetrafluoroethylene conductive sealing film as described in claim 1, characterized in that, In step S30 above, before rolling the second composite material with the expanded polytetrafluoroethylene film, the expanded polytetrafluoroethylene film is subjected to low-temperature plasma surface treatment to enhance the bonding force between the expanded polytetrafluoroethylene film and the second composite material.

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