Conductive paste, electrically heated fabric and method of making and use thereof

Abstract

The present application relates to the technical field of electric heating element, and specifically discloses a conductive paste, and further discloses an electric heating fabric based on the conductive paste, a preparation method and application thereof.The conductive paste comprises the following raw materials in percentage by mass: conductive functional particles 4-28%, polymer matrix 3-25%, solvent 40-90%, dispersing agent 0.1-5%, leveling agent 0.1-5%, and defoaming agent 0.1-5%.The conductive paste prepared by the present application has excellent high-temperature resistance, good process adaptability, stable resistance characteristics, and excellent compatibility and interface bonding strength with the composite matrix, thereby providing key material support for subsequent preparation of high-performance electric heating fabric and other electric heating functional structure integrated composites.

Description

Technical Field

[0001] This invention relates to the field of electric heating element technology, and more particularly to a conductive paste, as well as to an electric heating fabric based on the conductive paste, its preparation method, and its application. Background Technology

[0002] With the widespread application of composite materials in high-end equipment manufacturing fields such as aviation, aerospace, and wind power, achieving structural-functional integration has become a key approach to improving the performance and added value of composite materials. In particular, integrating electric heating anti-icing and de-icing functions with load-bearing structures is of great significance for improving the operational safety and reliability of equipment such as aircraft and wind turbines in low-temperature and high-humidity environments.

[0003] Civil aircraft, transport planes, helicopters, and wind turbine blades are prone to surface icing in low-temperature environments, severely impacting operational safety and efficiency. For example, wind turbine icing can lead to decreased power generation efficiency and even blade breakage, while aircraft wing icing can cause lift loss. Although composite materials are widely used in components such as wing leading edges and wind turbine blades, traditional de-icing technologies such as mechanical de-icing, thermal anti-icing, and wire electric heating are difficult to adapt to composite material structures. There is an urgent need to develop new electric heating materials and structural technologies that can be integrated with composite materials to achieve functional-structural integration.

[0004] Currently, composite materials are typically cured under high temperature and pressure using equipment such as autoclaves. To achieve integrated electrothermal functionality, the electrothermal material and the composite material need to be co-cured under high temperature and pressure. This requires the electrothermal material to have excellent high-temperature resistance, ensuring that its physicochemical properties do not change significantly during the high-temperature and high-pressure co-curing process. However, most existing electrothermal materials lack sufficient high-temperature resistance, easily decomposing, experiencing sudden changes in resistance, or undergoing interface failure during co-curing, affecting the component's function and mechanical properties. Furthermore, common electrothermal elements such as metal heating wires and carbon-based films have poor compatibility with the composite resin matrix, easily hindering resin flow during co-curing and leading to defects such as porosity and delamination within the component, thus restricting the quality of integrated molding. Simultaneously, current technology struggles to achieve uniform resistance and controllable thickness coatings on flexible fabrics, resulting in poor coating adaptability and localized overheating or heating blind spots in the electrothermal fabric. This not only affects large-area anti-icing and de-icing effects but also wastes energy and increases equipment operating costs. Therefore, there is an urgent need to develop a new type of conductive paste and a corresponding method for preparing electrically heated fabrics to solve problems such as high temperature resistance, process adaptability and resin compatibility, so as to meet the co-curing requirements of composite materials and promote the development of structural and functional integrated composite materials. Summary of the Invention

[0005] This invention provides a conductive paste that exhibits good compatibility with composite materials, effectively participating in the cross-linking and curing process of the composite matrix and significantly improving the interfacial bonding strength between the conductive heating layer and the composite material. Simultaneously, this invention also provides an electrically heated fabric, its preparation method, and its applications.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a conductive paste comprising, by mass percentage, the following raw materials: 4%-28% conductive functional particles, 3%-25% polymer matrix, 40%-90% solvent, 0.1%-5% dispersant, 0.1%-5% leveling agent, and 0.1%-5% defoamer; wherein the conductive functional particles include modified graphene, modified carbon nanotubes, conductive carbon black, and silver nanopowder, and the mass ratio of the modified graphene, modified carbon nanotubes, conductive carbon black, and silver nanopowder is (6-12):(2-6):(1-4):(0-3).

[0007] Furthermore, the modified graphene is prepared by treating graphene with polymer nanoparticles.

[0008] Furthermore, the modified carbon nanotubes are prepared by treating carbon nanotubes with polymer nanoparticles.

[0009] Compared to existing technologies, this invention employs polymer nanoparticles to non-covalently modify graphene / carbon nanotubes. This not only effectively prevents the aggregation of nanomaterials and improves their dispersion stability in the system, but also increases the crosslinking density of the coated film, reducing pores and defects. Secondly, this invention uses a scientific ratio to compound conductive materials of different dimensions, constructing a three-dimensional conductive network combining "points, lines, and surfaces," significantly improving conductivity and resistance distribution uniformity, effectively avoiding local overheating, and ensuring heating uniformity. Simultaneously, this invention selects high-temperature resistant polymers such as modified bismaleimide resin as the matrix, ensuring the structural stability and film-forming properties of the slurry system under high-temperature conditions. Ultimately, the resulting conductive slurry exhibits excellent high-temperature resistance, good process adaptability, stable resistance characteristics, and excellent compatibility and interfacial bonding strength with the composite matrix, providing key material support for the subsequent preparation of high-performance electrically heated fabrics and other integrated electrically heated functional composite materials.

[0010] More preferably, the preparation process of the modified graphene / modified carbon nanotubes is as follows: 1-20 parts by weight of graphene or 1-10 parts by weight of carbon nanotubes and 5-40 parts by weight of polymer nanoparticles are mixed and dispersed in a ball mill at a speed of 300-800 r / min to obtain the modified graphene / modified carbon nanotubes; wherein the mass ratio of powder (i.e., graphene or carbon nanotubes and polymer nanoparticles) to grinding balls is 1:(2-4). This preparation process uses mechanical grinding to uniformly coat the polymer nanoparticles onto the surface of graphene or carbon nanotubes through π-π interactions, which avoids the destruction of the intrinsic structure of carbon materials by traditional chemical modification and effectively improves the dispersibility and interfacial bonding of carbon materials in organic matrices.

[0011] In some preferred embodiments, the carbon nanotubes include single-walled carbon nanotubes and / or double-walled carbon nanotubes.

[0012] In some preferred embodiments, the median length of the carbon nanotubes is 0.1-1000 μm, such as 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 400 μm, 600 μm, 800 μm or 1000 μm, and more preferably 1-200 μm.

[0013] In some preferred embodiments, the graphene comprises monolayer graphene and / or multilayer graphene.

[0014] In some preferred embodiments, the average sheet diameter of the graphene is independently 0.1-2000 μm, such as 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 500 μm, 1000 μm, 1500 μm or 2000 μm, and more preferably 1-100 μm.

[0015] Furthermore, the polymer nanoparticles are selected from at least one of polyaniline, polypyrrole, polyphenylene acetylene, and poly(o-phenylenediamine).

[0016] Furthermore, the polymer matrix is ​​selected from at least one of modified bismaleimide resin, polyimide resin, and phenyl silicone resin.

[0017] Furthermore, the modified bismaleimide resin is prepared by copolymerization modification of bismaleimide resin and o-diallyl bisphenol A; the mass ratio of the bismaleimide resin to o-diallyl bisphenol A is 1:(0.8-1.2).

[0018] The preferred modified bismaleimide resin of this invention, by introducing flexible segments of o-diallylbisphenol A into the molecular chain, effectively improves its flexibility, processability, and interfacial compatibility with composite materials while maintaining the inherent heat resistance of bismaleimide resin. Using modified bismaleimide resin as the polymer matrix not only provides stable support for conductive functional particles and promotes the formation of a dense film, but also improves the heat resistance of the slurry system, enabling it to withstand high temperatures of 400°C for extended periods. Simultaneously, the active groups contained in the modified bismaleimide resin enhance the chemical bonding and physical anchoring effect with the composite matrix, ensuring good wetting and interfacial integrity of the resin during co-curing, and helping the slurry maintain suitable processing rheology and film-forming properties, ultimately providing stable mechanical and electrical performance support for the conductive heating layer.

[0019] More preferably, the temperature of the copolymerization modification treatment during the preparation of the modified bismaleimide resin is 100-140℃.

[0020] Furthermore, the solvent includes a divalent ester, N-methylpyrrolidone, and diethylene glycol ethyl ether acetate, wherein the mass ratio of the divalent ester, N-methylpyrrolidone, and diethylene glycol ethyl ether acetate is (0-3):(1-3):(1-3).

[0021] N-methylpyrrolidone, as a highly polar solvent, effectively dissolves polymer matrices (such as polyimide resins), ensuring the system's uniformity and stability. Diethylene glycol ethyl ether acetate possesses excellent leveling properties and a moderate evaporation rate, contributing to the formation of a smooth, defect-free film. Divalent esters delay surface drying time, promote thorough slurry leveling, and suppress bubble formation. This invention, by using a specific ratio of these three components as a solvent, achieves precise control over slurry viscosity, evaporation gradient, and film-forming properties. This ensures uniform dispersion of conductive particles, is suitable for various coating processes such as screen printing and spraying, and provides conditions for the smooth removal of organic matter during subsequent high-temperature drying, ultimately resulting in a dense, uniform, and firmly bonded conductive functional layer.

[0022] This invention does not impose any special requirements on the type of dispersant in the conductive paste. Exemplarily, the dispersant includes, but is not limited to, one or more of polymeric dispersants, anionic surfactants, or nonionic surfactants. The polymeric dispersant may be selected from BYK-110, BYK-163, EFKA-4010, EFKA-4050, polyvinylpyrrolidone, etc.; the anionic surfactant may be selected from sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium stearate, etc.; and the nonionic surfactant may be selected from fatty acid polyoxyethylene esters, sorbitan fatty acid esters, alkylphenol polyoxyethylene ethers, etc.

[0023] This invention does not impose any special requirements on the type of leveling agent in the conductive paste. Exemplarily, the leveling agent includes, but is not limited to, one or more of silicone-based leveling agents, acrylate-based leveling agents, or fluorocarbon-based leveling agents. The silicone-based leveling agent may be selected from polydimethylsiloxane, polyether-modified polydimethylsiloxane, alkyl-modified polydimethylsiloxane, etc.; the acrylate-based leveling agent may be selected from acrylate copolymers, fluorinated acrylate copolymers, etc.; and the fluorocarbon-based leveling agent may be selected from perfluoroalkyl ethers, fluorinated polyolefins, etc.

[0024] This invention does not impose any special requirements on the type of defoamer in the conductive paste. Exemplarily, the defoamer includes, but is not limited to, one or more of silicone defoamers, polyether-modified silicone defoamers, or non-silicone defoamers. The silicone defoamer may be selected from polydimethylsiloxane emulsions, silicone pastes, silicone oil complexes, etc.; the polyether-modified silicone defoamer may be selected from polyether-modified polydimethylsiloxane; the non-silicone defoamer may be selected from polyethers (such as polyoxyethylene polyoxypropylene glycerol ether), fatty acid esters, mineral oils, etc.

[0025] Secondly, the present invention provides a method for preparing the above-mentioned conductive paste, comprising the following steps: The conductive functional particles, polymer matrix, solvent, dispersant, leveling agent and defoamer are mixed and ball-milled to a fineness of ≤10μm to obtain the conductive slurry.

[0026] More preferably, the method for preparing the conductive paste includes the following steps: (1) The polymer matrix, solvent, dispersant, leveling agent and defoamer are mixed evenly to obtain a matrix dispersion; (2) The conductive functional particles are mixed with the matrix dispersion obtained in step (1) to obtain a conductive slurry dispersion; wherein, the specific proportion of each component can be adjusted according to the actual coating process, fiber fabric type and the performance requirements of sheet resistance of the electrically heated fabric. (3) The conductive slurry dispersion obtained in step (2) is ground and dispersed using a ball mill. The ball mill speed is controlled at 200-900 r / min. The slurry fineness is ground until it does not exceed 10 μm to obtain the conductive slurry. The mass ratio of the conductive slurry dispersion to the grinding balls is 1:(2-4). The grinding balls are zirconia grinding balls with a diameter of 1-5 mm.

[0027] Thirdly, the present invention provides an electrically heated fabric, comprising a fiber fabric base layer and a conductive heating layer disposed on at least one side of the fiber fabric base layer; the conductive heating layer is formed by curing the conductive paste provided by the present invention.

[0028] In some preferred embodiments, the fiber fabric base layer comprises a nonwoven fiber fabric or a woven fiber fabric; and the present invention does not have special requirements on the weave of the fiber fabric base layer. Exemplarily, the fiber fabric base layer can be a unidirectional fiber fabric, a plain weave fabric, a twill weave fabric, or a satin weave fabric.

[0029] Furthermore, the fiber fabric base layer is woven from inorganic fibers and / or organic fibers, and the present invention does not have any particular requirements on the specific types of inorganic and organic fibers. Exemplarily, the inorganic fibers include one or more of glass fibers, ceramic fibers, alumina fibers, or quartz fibers. Exemplarily, the organic fibers include one or more of polyester fibers, polyimide fibers, poly(p-benzimidazole) fibers, or aramid fibers.

[0030] Furthermore, the sheet resistance of the electrically heated fabric is 10-10000Ω / sq, such as 10Ω / sq, 20Ω / sq, 50Ω / sq, 100Ω / sq, 500Ω / sq, 1000Ω / sq, 2000Ω / sq, 5000Ω / sq, 8000Ω / sq, or 10000Ω / sq.

[0031] In some preferred embodiments, the thickness of the conductive heating layer is 1-20 μm, such as 0.5 μm, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm or 20 μm.

[0032] In some preferred embodiments, the thickness of the fiber fabric base layer is 40-200 μm, such as 40 μm, 45 μm, 50 μm, 80 μm, 100 μm, 150 μm or 200 μm.

[0033] Fourthly, the present invention provides a method for preparing the above-mentioned electrically heated fabric, comprising the following steps: The conductive paste is coated onto one or both sides of the fiber fabric substrate and dried at 200-400℃ for 10-60 minutes to form a conductive heating layer, thereby obtaining the electrically heated fabric.

[0034] In some preferred embodiments, the coating method includes any one or a combination of at least two of the following: blade coating, spray coating, casting, dip coating, or roller coating.

[0035] Fifthly, the present invention provides the application of the above-mentioned electrically heated fabric in the preparation of an integrated composite material with an electrically heated functional structure.

[0036] Furthermore, the preparation method of the electrically heated functional structure integrated composite material includes the following steps: (1) Design the size, shape and position of the electrode according to the actual application requirements, coat the corresponding area of ​​the electric heating fabric with conductive silver paste, and stick copper conductive tape, and then dry it at 120℃ for 20-40 min to obtain the electric heating fabric with electrode. (2) During the process of laying the prepreg, the above-mentioned electric heating fabric with electrodes is laid on the sub-surface and placed in an autoclave. It is then co-cured at 200-400℃ and 0.3-1.8MPa to obtain the integrated composite material with electric heating functional structure.

[0037] It should be noted that when the electrically heated fabric has a conductive heating layer on only one side of the fiber fabric base layer, its laying direction can be determined according to the specific application requirements. The conductive heating layer facing the surface or the base layer facing the surface can both meet the application requirements. In actual laying, it can be flexibly selected according to the interface design and heating efficiency requirements.

[0038] In this invention, the prepreg refers to an intermediate material made by impregnating reinforcing fibers (such as glass fiber, carbon fiber, quartz fiber, etc.) with a thermosetting or thermoplastic resin matrix and then subjecting it to certain treatments. This material can soften, melt, and undergo a curing reaction under heating and pressure conditions, ultimately forming a composite material product. In some preferred embodiments, the prepreg includes, but is not limited to, epoxy resin-based prepreg, bismaleimide resin-based prepreg, polyimide resin-based prepreg, phenolic resin-based prepreg, cyanate ester resin-based prepreg, benzoxazine resin-based prepreg, etc. The reinforcing fiber structure in the prepreg includes unidirectional fibers, plain weave fabric, twill weave fabric, satin weave fabric, or nonwoven fabric, etc. The selection of the prepreg can be made according to the mechanical properties, temperature resistance level, and process compatibility requirements of the final composite material, and its resin system should have good co-curing compatibility with the conductive paste and electrically heated fabric of this invention.

[0039] In summary, the present invention has the following beneficial effects: (1) This invention significantly improves the high-temperature resistance of electrically heated fabrics by using conductive functional particles such as modified graphene, modified carbon nanotubes, conductive carbon black, and silver nanoparticles, combined with a high-temperature resistant polymer matrix. The conductive slurry system has good compatibility with the composite material and can effectively participate in the cross-linking and curing process of the composite matrix. With the help of the active components, it forms a strong chemical bond and physical anchor with the composite matrix resin, which significantly improves the interfacial bonding strength between the conductive heating layer and the composite material, achieving a durable and stable bond. This is conducive to realizing an integrated composite material with stable electric heating functional structure, which can effectively play the function of electric heating and de-icing without affecting the overall service performance of the composite material.

[0040] (2) The electric heating fabric provided by the present invention has a suitable inter-wire pore structure, which allows the resin to flow smoothly during the curing process. This can effectively reduce the influence of the co-curing process on the physicochemical properties of the electric heating functional layer. In the final integrated composite material of electric heating functional structure, the resistance change rate of the electric heating fabric does not exceed ±8% before and after co-curing, showing excellent electrical stability.

[0041] (3) The surface resistance (sheet resistance) of the electrically heated fabric provided by the present invention can be effectively adjusted in a wide range of 10-10000 Ω / sq to meet the heating power requirements of different application scenarios, while having excellent heating uniformity and avoiding local overheating or heating blind spots.

[0042] (4) The electric heating fabric provided by the present invention has good flexibility. After bending test, its resistance change rate does not exceed ±5%, showing excellent mechanical durability and structural adaptability, and is suitable for the integration and application of complex surface structural parts.

[0043] (5) Based on the functional structure integrated composite material of the electric heating fabric, it exhibits an electrothermal conversion efficiency of over 90%, while having a low anti-icing power density and anti-icing temperature, resulting in significant energy-saving effect and meeting the performance requirements of high-efficiency, low-energy anti-icing and de-icing systems in aviation, wind power and other fields. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the integrated composite material with electric heating function structure in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of the electrically heated fabric with electrodes in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram showing the flow of resin in the quartz fiber reinforced bismaleimide resin-based prepreg through the pores between the strands of the electrically heated fabric in Embodiment 1 of the present invention. Detailed Implementation

[0045] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments will be briefly introduced below. Obviously, the embodiments described below are some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these embodiments without creative effort.

[0046] Where specific experimental steps or conditions are not specified in the embodiments, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. All raw materials or instruments used are commercially available conventional products, including but not limited to those used in the embodiments of this application.

[0047] Information on some of the raw materials involved in the following specific implementation methods is shown below: Bismaleimide resin: purchased from Honghu Shuangma New Material Technology Co., Ltd., brand name BMI-06; Phenyl silicone resin: purchased from Guangzhou Silok New Material Co., Ltd., brand name Silok-6164F; Polyimide resin: purchased from Changzhou Ya'an New Materials Co., Ltd., grade PI-300; Dispersant: Purchased from BYK GmbH, Germany, brand name BYK-2013; Defoamer: Purchased from Guangzhou Silok New Material Co., Ltd., brand name Silok-310F; Leveling agent: purchased from Guangzhou Silok New Material Co., Ltd., brand name Silok-4016; Carbon nanotubes: purchased from Shenzhen Feimo Technology Co., Ltd., grade XC-101, median length 50μm; Graphene: Purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., grade XFQ27, with an average sheet diameter of 5μm; Conductive carbon black: purchased from Lion Corporation of Japan, brand name ECP-600JD; Silver nanoparticles: purchased from Shanghai Pantian Powder Materials Co., Ltd., grade PT-AG-50m; The preparation process of the modified bismaleimide resin used in the following specific embodiments is as follows: Bismaleimide resin and o-diallylbisphenol A were placed in a reaction vessel at a mass ratio of 1:1. Under continuous stirring, the temperature of the reaction system was raised to 120°C to carry out a copolymerization modification reaction. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain modified bismaleimide resin.

[0048] The preparation process of the modified graphene used in the following specific embodiments is as follows: Ten parts by weight of graphene and 20 parts by weight of polyaniline nanoparticles were mixed and placed together in a ball mill jar. Zirconia grinding balls were added to the ball mill jar to ensure that the total mass ratio of the powder (i.e., the mixture of graphene / carbon nanotubes and polymer nanoparticles) to the grinding balls was 1:3. The mixture was ground and dispersed in a ball mill at a speed of 500 r / min to obtain modified graphene.

[0049] The preparation process of the modified carbon nanotubes used in the following specific embodiments is as follows: Five parts by weight of carbon nanotubes and 20 parts by weight of polyaniline nanoparticles were mixed and placed together in a ball mill jar. Zirconia grinding balls were added to the ball mill jar to ensure that the total mass ratio of the powder (i.e., the mixture of graphene / carbon nanotubes and polymer nanoparticles) to the grinding balls was 1:3. The mixture was ground and dispersed in a ball mill at a speed of 500 r / min to obtain modified carbon nanotubes.

[0050] Example 1 This embodiment provides a conductive paste, the composition and content of which are shown in Table 1 below. The conductive functional particles include modified graphene, modified carbon nanotubes, and conductive carbon black, with a mass ratio of 7:5:2. The solvents include divalent ester, N-methylpyrrolidone, and diethylene glycol ethyl ether acetate, with a mass ratio of approximately 3:2:2.

[0051] Table 1 This embodiment also provides a method for preparing the above-mentioned conductive paste, including the following steps: (1) Mix the polymer matrix, solvent, dispersant, leveling agent and defoamer evenly to obtain a matrix dispersion; (2) Add the pre-dried conductive functional particles to the matrix dispersion obtained in step (1) and continue to stir and mix until the particles are evenly dispersed to obtain a conductive slurry dispersion. (3) Transfer the conductive slurry dispersion obtained in step (2) to a ball mill, add zirconia grinding balls with a diameter of 3 mm (mass ratio of slurry to grinding balls is 1:3), and grind and disperse at a speed of 600 r / min until the fineness of the slurry reaches 9 μm to obtain conductive slurry.

[0052] This embodiment also provides an electrically heated fabric, including a fiber fabric base layer and a conductive heating layer disposed on one side surface of the fiber fabric base layer; the conductive heating layer is formed by curing the conductive paste provided in this embodiment; wherein, the fiber fabric base layer is woven from quartz fibers; The thickness of the fiber fabric base layer is 60 μm, and the thickness of the conductive heating layer is 2 μm.

[0053] This embodiment also provides a method for preparing the above-mentioned electrically heated fabric, including the following steps: The fibrous fabric substrate (i.e., quartz fiber fabric) was cleaned with anhydrous ethanol. Conductive paste was then coated onto the fibrous fabric substrate using screen printing. The paste viscosity was 60 Pa·s, the squeegee angle was set to 70°, and the screen mesh count was 200 mesh. In the specific operation, the fibrous fabric substrate was placed flat under the screen, an appropriate amount of conductive paste was poured over the screen, and the squeegee was used to scrape it at a uniform speed, so that the conductive paste was evenly transferred to the fabric surface through the mesh to form a printed wet film. The printed fabric was then dried at 200°C for 30 minutes to obtain the electrically heated fabric.

[0054] An integrated composite material with an electric heating functional structure was prepared using the electric heating fabric provided in this embodiment. A schematic diagram of the layup structure of the prepreg and the electric heating fabric in the integrated composite material is shown below. Figure 1 As shown, the preparation process is as follows: Conductive silver paste is coated onto the electrically heated fabric, and copper conductive tape is attached to form an electrode structure, as shown in the schematic diagram. Figure 2 As shown; then dried at 120°C for 30 min to obtain an electrically heated fabric with electrodes; When laying the quartz fiber reinforced bismaleimide resin-based prepreg (purchased from AVIC Composite Materials Co., Ltd.), the above-mentioned electrically heated fabric with electrodes was laid on the sub-surface position, and co-cured using an autoclave according to the following curing process: vacuum was drawn to a vacuum degree of 0.09 MPa at room temperature; the temperature was increased to 130°C at an average rate of 1°C / min and held for 2 hours; the pressure was increased to 0.4 MPa, and the temperature was further increased to 150°C and held for 1 hour; the temperature was increased again to 200°C and held for 4 hours; finally, the temperature was cooled to below 60°C while maintaining pressure, and the autoclave was opened to obtain the integrated composite material with electrically heated functional structure.

[0055] In the preparation process of the electrically heated functional structure integrated composite material, during the co-curing treatment, the pores between the wire bundles of the electrically heated fabric allow the resin to flow through during the curing process, as shown in the schematic diagram. Figure 3 As shown, the curing process can effectively reduce the changes in its physicochemical properties, and the resistance change rate of the high-temperature resistant electrically heated fabric before and after co-curing does not exceed ±8%.

[0056] Example 2 This embodiment provides a conductive paste, the composition and content of which are shown in Table 1 below. The conductive functional particles include modified graphene, modified carbon nanotubes, conductive carbon black, and silver nanoparticles, with a mass ratio of 8:6:1:1. The solvents include divalent ester, N-methylpyrrolidone, and diethylene glycol ethyl ether acetate, with a mass ratio of approximately 1.5:1.71:1.

[0057] Table 2 This embodiment also provides a method for preparing the above-mentioned conductive paste, including the following steps: (1) Mix the polymer matrix, solvent, dispersant, leveling agent and defoamer evenly to obtain a matrix dispersion; (2) Add the pre-dried conductive functional particles to the matrix dispersion obtained in step (1) and continue to stir and mix until the particles are evenly dispersed to obtain a conductive slurry dispersion. (3) Transfer the conductive slurry dispersion obtained in step (2) to a ball mill, add zirconia grinding balls with a diameter of 3 mm (mass ratio of slurry to grinding balls is 1:4), and grind and disperse at a speed of 400 r / min until the fineness of the slurry reaches 8 μm to obtain conductive slurry.

[0058] This embodiment also provides an electrically heated fabric, including a fiber fabric base layer and a conductive heating layer disposed on one side surface of the fiber fabric base layer; the conductive heating layer is formed by curing the conductive paste provided in this embodiment. The fiber fabric base layer is woven from quartz fibers.

[0059] This embodiment also provides a method for preparing the above-mentioned electrically heated fabric, including the following steps: The substrate layer of the fiber fabric (i.e., quartz fiber fabric) was cleaned with anhydrous ethanol. The conductive slurry was then coated onto the substrate layer of the fiber fabric using an dip-coating method. The slurry viscosity was 5 Pa·s, the dip-coating time was 20 s, the lifting speed was 0.6 m / min, the ambient temperature was between 25℃ and the air humidity was 60%. Subsequently, the coated fabric was dried at 100℃ for 10 min and then dried at 300℃ for 30 min to obtain the electrically heated fabric.

[0060] An integrated composite material with an electric heating functional structure was prepared using the electric heating fabric provided in this embodiment. The preparation process is as follows: Conductive silver paste was coated onto the electrically heated fabric, and copper conductive tape was attached to form an electrode structure. The fabric was then dried at 120°C for 30 minutes to obtain an electrically heated fabric with electrodes. When laying the quartz fiber reinforced polyimide resin-based prepreg (purchased from AVIC Composite Materials Co., Ltd.), the above-mentioned electrically heated fabric with electrodes was laid on the sub-surface position, and co-cured using an autoclave according to the following curing process: vacuuming to a vacuum degree of 0.1 MPa at room temperature; heating to 180°C at an average rate of 1°C / min and holding for 2 hours; pressurizing to 0.6 MPa, continuing to heat to 250°C and holding for 2 hours; heating again to 300°C and holding for 4 hours; finally cooling to below 60°C while maintaining pressure, opening the can and removing the product to obtain the integrated composite material with electrically heated functional structure.

[0061] Performance testing: The performance of the electrically heated fabric and the integrated composite material with electrically heated functional structure provided in Examples 1-2 of this invention was tested. The specific test methods are as follows: Sheet resistance: The sheet resistance of the electrically heated fabric was measured using a four-probe resistance meter according to YB / T "Determination of Sheet Resistance of Graphene Film by Four-Probe Method". The sheet resistance test result of Example 1 was about 28Ω / sq, and the sheet resistance test result of Example 2 was about 297Ω / sq. Interlaminar shear strength: The electrically heated functional structure integrated composite material was prepared into a sample, and then the interlaminar shear strength of the sample was tested according to the method specified in GB / T1450.1-2005 "Fiber Reinforced Plastics Interlaminar Shear Strength Test Method"; Bending resistance change rate: The resistance change is measured and the resistance change rate is calculated after the electrically heated fabric is bent 180° 10 times around a round rod with a diameter of 8mm±0.8mm. Electrothermal conversion efficiency: The electrically heated fabric membrane was completely immersed in a container containing m kg of deionized water, ensuring the heating membrane was not in contact with the container wall. The initial water temperature T0 was measured using a thermocouple. A voltage of 200V was applied to the electrically heated fabric membrane for heating, and the current value I passing through the heating membrane was recorded. After 60 minutes, the water was thoroughly stirred to ensure uniform water temperature throughout the container, and the water temperature was measured using a thermocouple until the temperature no longer changed. The heating time t and water temperature T1 at this point were recorded. The electrothermal conversion efficiency was calculated using the following formula: In the formula, E is the electrothermal conversion efficiency (%), U is the voltage (V), I is the current (A), t is the heating time (s), and c is the specific heat capacity of deionized water (4200 J·kg⁻¹). -1 ·K -1 T1 is the final temperature of the water (K), T0 is the initial temperature of the water (K), and m is the mass of the water (kg). Resistance change rate before and after co-curing: The resistance values ​​of the electrically heated fabric and the prepreg were measured before and after co-curing during the preparation of the electrically heated functional structure integrated composite material, and the resistance change rate was calculated. Tensile strength: The electrically heated functional structure integrated composite material was prepared into a sample, and then the tensile strength of the composite material sample was tested according to the method specified in GB / T 5210-2006 "Test for pull adhesion of paints and varnishes"; Anti-icing performance test: Samples of the integrated composite material with electric heating functional structure were prepared and placed in an ice wind tunnel for anti-icing performance testing; the ambient wind speed was 150 m / s, the ambient temperature was -10℃, and the liquid water content was 1.00 g / m³. 3 The minimum anti-icing power density was tested under the experimental conditions of an average effective diameter of water droplets of 20 μm.

[0062] Table 3 As can be seen from the data in Table 3, the integrated composite material of electric heating fabric and electric heating functional structure provided by the present invention has good high temperature resistance, electrothermal efficiency, interfacial bonding strength, mechanical flexibility and process stability, which fully meets the requirements of aviation, aerospace, wind power and other fields for high performance and high reliability integrated composite materials of electric heating functional structure.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrically conductive paste, characterized by, The preparation materials, by weight percentage, include: 4%-28% conductive functional particles, 3%-25% polymer matrix, 40%-90% solvent, 0.1%-5% dispersant, 0.1%-5% leveling agent, and 0.1%-5% defoamer; The conductive functional particles include modified graphene, modified carbon nanotubes, conductive carbon black, and silver nanoparticles, wherein the mass ratio of the modified graphene, modified carbon nanotubes, conductive carbon black, and silver nanoparticles is (6-12):(2-6):(1-4):(0-3); the modified graphene is prepared by treating graphene with polymer nanoparticles; the modified carbon nanotubes are prepared by treating carbon nanotubes with polymer nanoparticles; the polymer nanoparticles are selected from at least one of polyaniline, polypyrrole, polyphenylene acetylene, and poly(o-phenylenediamine). The solvent includes divalent ester, N-methylpyrrolidone, and diethylene glycol ethyl ether acetate, wherein the mass ratio of the divalent ester, N-methylpyrrolidone, and diethylene glycol ethyl ether acetate is 3:2:2 or 1.5:1.71:

1. The polymer matrix is ​​selected from at least one of modified bismaleimide resin, polyimide resin, and phenyl silicone resin.

2. The conductive paste of claim 1, wherein, The modified bismaleimide resin was prepared by copolymerization modification of bismaleimide resin and o-diallyl bisphenol A; The mass ratio of the bismaleimide resin to o-diallyl bisphenol A is 1:(0.8-1.2).

3. A method of preparing the electroconductive paste according to any one of claims 1 to 2, characterized by, Includes the following steps: The conductive functional particles, polymer matrix, solvent, dispersant, leveling agent and defoamer are mixed and ball-milled to a fineness of ≤10μm to obtain the conductive slurry.

4. An electrically heated fabric, characterized in that, It includes a fiber fabric base layer and a conductive heating layer disposed on at least one side of the fiber fabric base layer; the conductive heating layer is formed by curing the conductive paste according to any one of claims 1-2.

5. A method of making an electrically heating fabric as claimed in claim 4, characterised in that, Includes the following steps: The conductive paste is coated onto one or both sides of the fiber fabric substrate layer and dried at 200-400℃ for 10-60 minutes to form a conductive heating layer, thereby obtaining the electrically heated fabric.

6. The application of the electroheating fabric according to claim 4 in the preparation of an integrated electroheating functional structure composite material.

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