Conductive slurry, electric heating fabric and preparation method and application thereof

Abstract

The invention relates to the technical field of electric heating elements, particularly discloses conductive paste, and further discloses electric heating fabric based on the conductive paste and a preparation method and application of the electric heating fabric. The conductive paste provided by the invention is prepared from the following raw materials in percentage by mass: 4%-28% of conductive functional particles, 3%-25% of a polymer matrix, 40%-90% of a solvent, 0.1%-5% of a dispersing agent, 0.1%-5% of a flatting agent and 0.1%-5% of a defoaming agent. The conductive paste prepared by the invention has excellent high-temperature resistance, good process adaptability, stable resistance characteristic and excellent compatibility and interface bonding strength with a composite material matrix, and provides a key material support for subsequent preparation of electric heating functional structure integrated composite materials such as high-performance electric heating fabrics and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric heating elements, in particular to a conductive paste, and also relates to an electric heating fabric based on the conductive paste, a preparation method therefor and an application thereof. BACKGROUND

[0002] With the wide application of composite materials in the fields of high-end equipment manufacturing such as aviation, aerospace and wind power, the realization of structural and functional integration has become a key approach to improving the performance and added value of composite materials. Among them, the integration of electric heating deicing function and load-bearing structure is of great significance to improve the operation safety and reliability of aircraft, wind turbines and other equipment in low-temperature and high-humidity environments.

[0003] Civil aircraft, transport aircraft, helicopters and wind turbine blades and other equipment are prone to surface icing in low-temperature environments, which seriously affects the operation safety and efficiency. For example, wind turbine icing can lead to a decrease in power generation efficiency or even blade fracture, and aircraft wing icing can cause lift loss. Although composite materials have been widely used in wing leading edges, wind turbine blades and other components, traditional deicing technologies such as mechanical deicing, thermal deicing and metal wire electric heating are difficult to adapt to composite structures, and new electric heating materials and structural technologies that can be integrated with composite materials and realize functional structural integration are urgently needed.

[0004] Currently, composite materials are usually cured at high temperature and high pressure using equipment such as autoclaves, and to realize the integration of electric heating function and structure, the electric heating material and the composite material need to be co-cured at high temperature and high pressure, which requires the electric heating material to have good high-temperature resistance and its physical and chemical properties not to change significantly during the co-curing process. However, most existing electric heating materials have insufficient high-temperature resistance, and are prone to decomposition, resistance mutation or interface failure during the co-curing process, affecting the function and mechanical properties of the component. In addition, common electric heating elements such as metal heating wires and carbon-based films have poor compatibility with the resin matrix of composite materials, which can hinder the flow of resin during the co-curing process, resulting in defects such as porosity and delamination in the component, and restricting the quality of integrated molding. At the same time, current technologies are difficult to achieve a coating with uniform resistance and controllable thickness on a flexible fabric, and have weak adaptability, resulting in local overheating or heating blind spots in the electric heating fabric, which not only affects the deicing effect of large areas, but also causes energy waste and increases the operating cost of the equipment. Therefore, it is urgent to develop a new type of conductive paste and a corresponding preparation method for electric heating fabric to solve the problems of 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

[0005] The application provides a conductive paste which has good compatibility with a composite material, can effectively participate in a cross-linking and curing process of a composite material matrix, and significantly improves the interfacial bonding strength between a conductive heating layer and the composite material.

[0006] To achieve the above-mentioned application purposes, the application adopts the following technical solutions: In a first aspect, the application provides a conductive paste containing the following preparation raw materials in terms of mass percentage: conductive functional particles 4%-28%, polymer matrix 3%-25%, solvent 40%-90%, dispersant 0.1%-5%, leveling agent 0.1%-5%, and defoaming agent 0.1%-5%; the conductive functional particles include modified graphene, modified carbon nanotube, conductive carbon black, and silver nano powder, and the mass ratio of the modified graphene, the modified carbon nanotube, the conductive carbon black, and the silver nano powder is (6-12):(2-6):(1-4):(0-3).

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

[0008] Further, the modified carbon nanotube is prepared by treating carbon nanotube with polymer nanoparticles.

[0009] Compared with the prior art, the application adopts polymer nanoparticles to non-covalently modify graphene / carbon nanotube, which not only effectively prevents the agglomeration of nanomaterials, improves the dispersion stability of the nanomaterials in the system, but also increases the cross-linking density of the coated film layer, reduces the pores and defects of the film layer; secondly, the application compounding different dimensional conductive materials by scientific proportioning, constructs a three-dimensional conductive network combined with "point-line-surface", greatly improves the conductive efficiency and resistance distribution uniformity, effectively avoids local overheating, and guarantees the heating uniformity; meanwhile, the application selects modified bismaleimide resin and other high-temperature-resistant polymers as the matrix, guarantees the structural stability and film-forming performance of the paste system in a high-temperature environment, and finally makes the prepared conductive paste exhibit excellent high-temperature resistance, good process adaptability, stable resistance characteristics, and excellent compatibility and interfacial bonding strength with the composite material matrix, which provides key material support for subsequent preparation of high-performance electric heating fabric and other electric heating functional structure integrated composite materials.

[0010] Further preferably, the preparation process of the modified graphene / modified carbon nanotube is as follows: The graphene or carbon nanotube 1-20 parts by weight, 5-40 parts by weight of polymer nanoparticles are mixed, and the grinding dispersion is carried out in a ball mill at a speed of 300-800 r / min, to obtain the modified graphene / modified carbon nanotube; wherein the mass ratio of powder (i.e. graphene or carbon nanotube and polymer nanoparticles) to grinding ball is 1: (2-4). The preparation process makes the polymer nanoparticles uniformly coated on the surface of graphene or carbon nanotube through π-π interaction by mechanical grinding, which not only avoids the damage to the intrinsic structure of carbon materials by traditional chemical modification, but also effectively improves the dispersibility and interfacial bonding force of carbon materials in organic matrix.

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

[0012] In some preferred embodiments, the carbon nanotubes have a median length of 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 further preferably 1-200 μm.

[0013] In some preferred embodiments, the graphene comprises single-layer graphene and / or multi-layer graphene.

[0014] In some preferred embodiments, the graphene has an average flake diameter of 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 further preferably 1-100 μm.

[0015] Further, the polymer nanoparticles are selected from at least one of polyaniline, polypyrrole, polyphenylenevinylene and polyo-phenylenediamine.

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

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

[0018] The modified bismaleimide resin of the present application effectively improves the flexibility, processability and interface compatibility with the composite material while maintaining the inherent heat resistance of the bismaleimide resin by introducing a flexible segment of o-diallyl bisphenol A into the molecular chain. Using the modified bismaleimide resin as the polymer matrix not only provides stable support for the conductive functional particles and promotes the formation of a dense film layer, but also improves the heat resistance of the paste system, allowing it to withstand high temperatures of 400℃ for a long period of time. At the same time, the active groups contained in the modified bismaleimide resin enhance the chemical bonding and physical anchoring with the composite matrix, ensuring good infiltration and interface integrity of the resin during the co-curing process, and helping the paste to maintain appropriate processing rheological properties and film-forming properties, ultimately providing stable mechanical and electrical performance support for the conductive heating layer.

[0019] Further preferably, the temperature of the copolymerization modification process in the preparation of the modified bismaleimide resin is 100-140℃.

[0020] Further, the solvent includes divalent acid ester, N-methyl pyrrolidone and diethylene glycol ethyl ether acetate, and the mass ratio of the divalent acid ester, N-methyl pyrrolidone and diethylene glycol ethyl ether acetate is (0-3):(1-3):(1-3).

[0021] N-methyl pyrrolidone as a strong polar solvent can effectively dissolve the polymer matrix (such as polyimide resin), ensuring the stability of the system; diethylene glycol ethyl ether acetate has good leveling property and moderate evaporation rate, which helps to form a smooth and defect-free film layer; divalent acid ester can delay the surface drying time, promote the paste to flow smoothly and inhibit the generation of bubbles. By compounding the three in a specific ratio as a solvent, the present application realizes precise control of the viscosity, evaporation gradient and film-forming property of the paste, which not only ensures the uniform dispersion of conductive particles, but also 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 obtaining a dense, uniform and firmly bonded conductive functional layer.

[0022] The present application does not have special requirements for the type of dispersant in the conductive paste. Illustratively, the dispersant includes but is not limited to one or more of a high molecular dispersant, an anionic surfactant or a non-ionic surfactant. The high molecular dispersant can be selected from BYK-110, BYK-163, EFKA-4010, EFKA-4050, polyvinyl pyrrolidone, etc.; the anionic surfactant can be selected from sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium stearate, etc.; the non-ionic surfactant can be selected from fatty acid polyoxyethylene ester, sorbitan fatty acid ester, alkyl phenol polyoxyethylene ether, etc.

[0023] The present application does not have special requirements for the type of leveling agent in the conductive paste. Illustratively, the leveling agent includes but is not limited to one or more of silicone leveling agent, acrylate leveling agent or fluorocarbon compound leveling agent. The silicone leveling agent can be selected from polydimethylsiloxane, polyether modified polydimethylsiloxane, alkyl modified polydimethylsiloxane and the like; the acrylate leveling agent can be selected from acrylate copolymer, fluorine modified acrylate copolymer and the like; the fluorocarbon compound leveling agent can be selected from perfluoroalkyl ether, fluorine modified polyolefin and the like.

[0024] The present application does not have special requirements for the type of defoaming agent in the conductive paste. Illustratively, the defoaming agent includes but is not limited to one or more of silicone defoaming agent, polyether modified silicone defoaming agent or non-silicon defoaming agent. The silicone defoaming agent can be selected from polydimethylsiloxane emulsion, silicone paste, silicone oil compound and the like; the polyether modified silicone defoaming agent can be selected from polyether modified polydimethylsiloxane; the non-silicon defoaming agent can be selected from polyether (such as polyoxyethylene polyoxypropylene glycerol ether), fatty acid ester, mineral oil and the like.

[0025] In a second aspect, the present application provides a preparation method of the above-mentioned conductive paste, comprising the following steps: The conductive functional particles, the polymer matrix, the solvent, the dispersing agent, the leveling agent and the defoaming agent are mixed and treated by ball milling to a fineness of ≤10 μm to obtain the conductive paste.

[0026] Further preferably, the preparation method of the conductive paste comprises the following steps: (1) uniformly mixing the polymer matrix, the solvent, the dispersing agent, the leveling agent and the defoaming agent to obtain a matrix dispersion liquid; (2) mixing the conductive functional particles with the matrix dispersion liquid obtained in step (1) to obtain a conductive paste dispersion liquid; wherein the specific ratio of each component can be adjusted according to the actual coating process, the type of fiber fabric and the performance requirements of the electrical heating fabric sheet resistance; (3) grinding and dispersing the conductive paste dispersion liquid obtained in step (2) by a ball mill, the rotation speed of the ball mill is controlled at 200-900 r / min, and the grinding is performed to a paste fineness of not more than 10 μm to obtain the conductive paste; wherein the mass ratio of the conductive paste dispersion liquid to the grinding ball is 1: (2-4), and the grinding ball is a zirconium oxide grinding ball with a diameter of 1-5 mm.

[0027] In a third aspect, the present application provides an electrical heating fabric, comprising a fiber fabric base layer and a conductive heating layer arranged 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 application.

[0028] In some preferred embodiments, the fibrous fabric base layer comprises a fibrous non-woven fabric or a fibrous woven fabric; and the present application does not have special requirements for the organization form of the fibrous fabric base layer. Illustratively, the fibrous fabric base layer can be a fibrous unidirectional fabric, a plain woven fabric, a twill woven fabric or a satin woven fabric.

[0029] Further, the fibrous fabric base layer is woven by inorganic fibers and / or organic fibers, and the present application does not have special requirements for the specific types of the inorganic fibers and the organic fibers. Illustratively, the inorganic fibers include one or more of glass fibers, ceramic fibers, alumina fibers or quartz fibers. Illustratively, the organic fibers include one or more of polyester fibers, polyimide fibers, poly-p-phenylene-benzimidazole fibers or aramid fibers.

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

[0031] In some preferred embodiments, the thickness of the electrically 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, etc.

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

[0033] In a fourth aspect, the present application provides a preparation method of the above-mentioned electrically heated fabric, comprising the following steps: applying the conductive paste to one side or both sides of the fibrous fabric base layer, drying at 200-400 °C for 10-60 min to form an electrically conductive heating layer, thereby obtaining the electrically heated fabric.

[0034] In some preferred embodiments, the coating method comprises any one or a combination of at least two of blade coating, spray coating, flow coating, dip coating or roll coating.

[0035] In a fifth aspect, the present application provides the use of the above-mentioned electrically heated fabric in the preparation of an electrically heated functional structure integrated composite material.

[0036] Further, the preparation method of the electrically heated functional structure integrated composite material comprises the following steps: (1) Design the size, shape and position of the electrode according to the actual application requirements, coat the conductive silver glue on the corresponding area of the electric heating fabric, and paste the copper conductive adhesive tape, then dry at 120℃ for 20-40min to obtain the electric heating fabric with electrode; (2) In the process of laying and pasting the prepreg, the electric heating fabric with electrode is laid on the sub-surface layer and placed in a hot press tank for co-curing treatment under the conditions of 200-400℃ and 0.3-1.8MPa to obtain the electric heating functional structure integrated composite material.

[0037] It should be noted that when the electric heating fabric is provided with a conductive heating layer only on one side of the fiber fabric base layer, the laying direction can be determined according to the specific application requirements, and the conductive heating layer can face the surface layer or the base layer, which can meet the use requirements. The interface design and heating efficiency requirements can be flexibly selected during actual laying.

[0038] In the present application, the prepreg refers to an intermediate material prepared by impregnating a reinforcing fiber (such as glass fiber, carbon fiber, quartz fiber, etc.) into a thermosetting or thermoplastic resin matrix and then processing it under certain conditions. The material can be softened, melted and cured under heating and pressing conditions, and finally forms 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 in the prepreg includes unidirectional fiber, plain woven cloth, twill woven cloth, satin woven cloth or non-woven 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 the resin system thereof should have good co-curing compatibility with the conductive paste and the electric heating fabric.

[0039] In summary, the present application has the following advantages: (1) The present application uses modified graphene, modified carbon nanotubes, conductive carbon black and silver nano powder as conductive functional particles, and combines with a high-temperature resistant polymer matrix to significantly improve the high-temperature resistance of the electric heating fabric. The conductive paste system has good compatibility with the composite material, can effectively participate in the crosslinking and curing process of the composite material matrix, form a firm chemical bond and physical anchoring with the active components and the composite material matrix resin, significantly improve the interfacial bonding strength between the conductive heating layer and the composite material, realize durable and stable bonding, and is conducive to realizing the electric heating functional structure integrated composite material with stable performance. While effectively playing the electric heating deicing function, it does not affect the overall service performance of the composite material.

[0040] (2) The electric heating fabric provided by the application has a suitable inter-wire bundle pore structure, so that the resin can flow smoothly and pass through during the curing process, and the influence of the co-curing process on the physical and chemical properties of the electric heating functional layer can be effectively reduced, so that the resistance change rate of the electric heating fabric in the finally obtained electric heating functional structure integrated composite material is not more than ±8% before and after co-curing, and excellent electrical stability is shown.

[0041] (3) The surface resistance (square resistance) of the electric heating fabric provided by the application can be effectively controlled in a wide range of 10-10000 Ω / sq, which can adapt to the demand of different application scenarios for heating power, and at the same time, the electric heating fabric has excellent heating uniformity, which can avoid local overheating or heating blind area.

[0042] (4) The electric heating fabric provided by the application has good flexibility, and the resistance change rate thereof is not more than ±5% after the bending test, which shows excellent mechanical durability and structural adaptability, and is suitable for integration and application of complex surface structure components.

[0043] (5) The functional structure integrated composite material based on the electric heating fabric shows an electric heating conversion efficiency higher than 90%, and at the same time, has a low anti-icing power density and anti-icing temperature, and the energy saving effect is remarkable, which meets the performance requirements of the aviation, wind power and other fields for high-efficiency and low-energy-consumption anti-icing systems. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings. Figure 1 It is a structural schematic diagram of the electric heating functional structure integrated composite material in the embodiment 1 of the application. Figure 2 It is a structural schematic diagram of the electric heating fabric with electrodes in the embodiment 1 of the application. Figure 3 It is a flow schematic diagram of the resin in the quartz fiber reinforced bismaleimide resin-based prepreg in the embodiment 1 of the application through the inter-wire bundle pores of the electric heating fabric. DETAILED DESCRIPTION

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the technical solutions in the embodiments of the application. Obviously, the embodiments in the following description are some embodiments of the application, and other embodiments can be obtained by those skilled in the art without any creative effort on the basis of these embodiments.

[0046] Unless otherwise indicated, the specific experimental procedures or conditions in the examples are carried out according to the conventional experimental procedures described in the literature. The raw materials or instruments used are conventional products that can be obtained commercially, including but not limited to the raw materials or instruments used in the examples of the present application.

[0047] Information about some of the raw materials involved in the following specific embodiments is shown below: Bismaleimide resin: purchased from Honghu City Bismaleimide New Material Technology Co., Ltd., with the brand name BMI-06; Phenyl silicone resin: purchased from Guangzhou Silok New Material Co., Ltd., with the brand name Silok-6164F; Polyimide resin: purchased from Changzhou Yayan New Material Co., Ltd., with the brand name PI-300; Dispersant: purchased from BYK Company, Germany, with the brand name BYK-2013; Defoaming agent: purchased from Guangzhou Silok New Material Co., Ltd., with the brand name Silok-310F; Leveling agent: purchased from Guangzhou Silok New Material Co., Ltd., with the brand name Silok-4016; Carbon nanotube: purchased from Shenzhen Feimo Technology Co., Ltd., with the brand name XC-101, with a median length of 50 μm; Graphene: purchased from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd., with the brand name XFQ27, with an average flake diameter of 5 μm; Conductive carbon black: purchased from Japan Lion, with the brand name ECP-600JD; Silver nano powder: purchased from Shanghai Pantian Powder Material Co., Ltd., with the brand name PT-AG-50m; The preparation process of the modified bismaleimide resin used in the following specific embodiments is as follows: The bismaleimide resin and the ortho-diallyl bisphenol A are placed in a reaction container in a mass ratio of 1:1, and the temperature of the reaction system is raised to 120°C under continuous stirring for copolymerization modification reaction. After the reaction is completed, it is cooled to room temperature, discharged, and the modified bismaleimide resin is obtained.

[0048] The preparation process of the modified graphene used in the following specific embodiments is as follows: 10 parts by weight of graphene and 20 parts by weight of polyaniline nanoparticles are mixed together and placed in a ball mill tank, zirconium oxide grinding balls are added to the ball mill tank 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 is 1:3, and the grinding and dispersion are carried out in a ball mill at a speed of 500 r / min to obtain the 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 60μm, and the thickness of the conductive heating layer is 2μm.

[0053] This embodiment also provides a method for preparing the above-mentioned electrically heated fabric, including the following steps: The fiber fabric base layer (i.e., quartz fiber fabric) is cleaned with anhydrous ethanol, and a conductive paste is coated on the fiber fabric base layer by screen printing, wherein the viscosity of the paste is 60 Pa·s, the squeegee angle is set to 70°, and the mesh number of the screen is 200 meshes; in the specific operation, the fiber fabric base layer is placed flat under the screen, an appropriate amount of conductive paste is poured above the screen, and the squeegee is used to evenly scrape over, so that the conductive paste is uniformly transferred to the surface of the fabric through the mesh holes to form a printed wet film; then the printed fabric is dried at 200℃ for 30min to obtain the electric heating fabric.

[0054] An electric heating functional structure integrated composite material is prepared by using the electric heating fabric provided in the embodiment, and a schematic diagram of the laying structure of the prepreg and the electric heating fabric in the electric heating functional structure integrated composite material is as shown in Figure 1 The preparation process is as follows: The conductive silver glue is coated on the electric heating fabric, and the copper conductive adhesive tape is pasted to form an electrode structure, and a schematic diagram of the structure is as shown in Figure 2 Then the electric heating fabric with electrodes is prepared by drying at 120℃ for 30min; When laying the quartz fiber reinforced bismaleimide resin-based prepreg (purchased from China Aviation Composite Material Co., Ltd.), the above electric heating fabric with electrodes is laid in the position of the secondary skin layer, and the co-curing treatment is carried out by using the autoclave equipment according to the following curing process: vacuumizing at room temperature to a vacuum degree of 0.09MPa; increasing the temperature to 130℃ at an average rate of 1℃ / min and keeping for 2h; pressurizing to 0.4MPa, continuously increasing the temperature to 150℃, keeping for 1h; increasing the temperature to 200℃ again, keeping for 4h; finally, cooling to below 60℃ under the condition of keeping the pressure, opening the tank to take out, to obtain the electric heating functional structure integrated composite material.

[0055] In the preparation process of the electric heating functional structure integrated composite material, the pores existing between the wire bundles of the electric heating fabric can allow the resin to flow through during the curing process, as shown in the schematic diagram Figure 3 It can effectively reduce the change of the physical and chemical properties during the curing process, and the resistance change rate of the high-temperature resistant electric heating fabric before and after co-curing is not more than ±8%.

[0056] Example 2 The raw material composition and content of the conductive paste provided in the embodiment are shown in Table 1. The conductive functional particles include modified graphene, modified carbon nanotube, conductive carbon black and silver nano powder, and the mass ratio of the modified graphene, modified carbon nanotube, conductive carbon black and silver nano powder is 8:6:1:1. The solvents include divalent acid ester, N-methyl pyrrolidone and diethylene glycol ether acetate, and the mass ratio of the divalent acid ester, N-methyl pyrrolidone and diethylene glycol ether acetate is about 1.5:1.71:1.

[0057] Table 2 The embodiment also provides a preparation method of the conductive paste, comprising the following steps: (1) uniformly mixing a polymer matrix, a solvent, a dispersant, a leveling agent and a defoaming agent to obtain a matrix dispersion liquid; (2) adding the conductive functional particles subjected to pre-drying treatment into the matrix dispersion liquid obtained in step (1) and continuing to stir and mix until the particles are uniformly dispersed to obtain a conductive paste dispersion liquid; (3) transferring the conductive paste dispersion liquid obtained in step (2) into a ball mill, adding zirconium oxide grinding balls with a diameter of 3 mm (the mass ratio of the paste to the grinding balls is 1:4), and performing grinding and dispersion at a rotation speed of 400 r / min until the fineness of the paste reaches 8 μm to obtain the conductive paste.

[0058] The embodiment also provides an electric heating fabric, comprising a fiber fabric base layer and a conductive heating layer arranged on one side surface of the fiber fabric base layer; the conductive heating layer is formed by curing the conductive paste provided by the embodiment. The fiber fabric base layer is made of quartz fibers.

[0059] The embodiment also provides a preparation method of the electric heating fabric, comprising the following steps: cleaning the fiber fabric base layer (i.e. a quartz fiber fabric) with anhydrous ethanol, coating the conductive paste on the fiber fabric base layer by using a dip coating method, wherein the viscosity of the paste is 5 Pa·s, the dip coating time is 20 s, the pulling speed is 0.6 m / min, the environmental temperature is between 25℃, and the air humidity is 60%; then drying the dip-coated fabric at 100℃ for 10 min and at 300℃ for 30 min to obtain the electric heating fabric.

[0060] An electric heating functional structure integrated composite material is prepared by using the electric heating fabric provided by the embodiment, and the preparation process is as follows: coating a conductive silver adhesive on the electric heating fabric and pasting a copper conductive adhesive tape to form an electrode structure, and then drying at 120℃ for 30 min to obtain an electric heating fabric with electrodes; In the process of laying the quartz fiber reinforced polyimide resin matrix prepreg (purchased from China Aviation Composite Material Co., Ltd.), the above electrode-equipped electric heating fabric is laid in the sub-surface layer position, and co-curing treatment is carried out by using a hot press tank device according to the following curing process: vacuumizing at room temperature to a vacuum degree of 0.1 MPa; increasing the temperature to 180℃ at an average rate of 1℃ / min and keeping for 2h; pressurizing to 0.6 MPa, continuing to increase the temperature to 250℃, keeping for 2h; increasing the temperature to 300℃ again, keeping for 4h; finally, cooling to below 60℃ under the condition of keeping the pressure, opening the tank to take out, and obtaining the electric heating functional structure integrated composite material.

[0061] Performance test: The electric heating fabric and the electric heating functional structure integrated composite material provided by the embodiments 1-2 of the present application are subjected to performance test, and the specific test method is as follows: Sheet resistance: the sheet resistance of the electric heating fabric is measured by using a four-probe resistance meter according to YB / T “Determination of sheet resistance of graphene film-four-probe method”, the sheet resistance test result of the embodiment 1 is about 28Ω / sq, and the sheet resistance test result of the embodiment 2 is about 297Ω / sq; Interlaminar shear strength: the electric heating functional structure integrated composite material is prepared into a sample, and then the interlaminar shear strength of the sample is tested according to the method specified in GB / T1450.1-2005 “Interlaminar shear strength test method for fiber reinforced plastics”; Bending resistance change rate: the electric heating fabric is bent 180° for 10 times around a round bar with a diameter of 8mm±0.8mm, and then the resistance change is tested, and the resistance change rate is calculated; Electric heating conversion efficiency: the electric heating fabric film is completely immersed in a container containing m kg of deionized water, and the heating film is kept from contacting the container wall; the initial temperature T0 of the water is measured by using a thermocouple, a voltage of 200V is input to the electric heating fabric for loading and heating, and the current value I passing through the heating film is recorded; after 60min, the water temperature of each part of the container is uniformly stirred, and the temperature of the water is measured by using a thermocouple until the temperature no longer changes, and the heating time t and the water temperature T1 at this time are recorded, and the electric heating conversion efficiency is calculated according to the following formula: In the formula, E is the electric heating conversion efficiency (%), U is the voltage (V), I is the current (A), t is the heating time (s), c is the specific heat capacity of deionized water (4200J·Kg -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 electric heating fabric and the prepreg before and after co-curing to form the electric heating functional structure integrated composite material are respectively measured, and the resistance change rate is calculated; Pull-off strength: the electric heating functional structure integrated composite material is prepared into a sample, and then the pull-off strength of the composite material sample is tested according to the method specified in GB / T 5210-2006 "Paints and varnishes - Pull-off adhesion test"; Anti-icing performance test: the electric heating functional structure integrated composite material is prepared into a sample, and is placed in an ice wind tunnel for anti-icing performance test; under the test conditions that the environmental wind speed is 150 m / s, the environmental temperature is-10℃, the liquid water content is 1.00 g / m 3 , and the average effective diameter of water droplets is 20 μm, the minimum anti-icing power density is tested.

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

[0063] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A conductive paste, characterized in that, 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, and 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).

2. The conductive paste as described in claim 1, characterized in that, The modified graphene is prepared by treating graphene with polymer nanoparticles; and / or The modified carbon nanotubes are prepared by treating carbon nanotubes with polymer nanoparticles.

3. The conductive paste as described in claim 2, characterized in that, The polymer nanoparticles are selected from at least one of polyaniline, polypyrrole, polyphenylene acetylene, and poly(o-phenylenediamine).

4. The conductive paste as described in claim 1, characterized in that, The polymer matrix is ​​selected from at least one of modified bismaleimide resin, polyimide resin, and phenyl silicone resin.

5. The conductive paste as described in claim 4, characterized in that, 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).

6. The conductive paste as described in claim 1, characterized in that, 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 (0-3):(1-3):(1-3).

7. A method for preparing the conductive paste according to any one of claims 1-6, characterized in that, 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.

8. 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 1-6.

9. A method for preparing the electrically heated fabric according to claim 8, characterized 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.

10. The application of the electrically heated fabric according to claim 8 in the preparation of an integrated electrically heated functional structure composite material.

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