Carbon nanotube conductive ink, electric heating film based on the conductive ink

Abstract

The application relates to the technical field of film materials, and particularly discloses a carbon nano conductive ink and an electric heating film prepared based on the carbon nano conductive ink. The preparation raw material of the carbon nano conductive ink comprises conductive functional particles, and the conductive functional particles comprise modified graphene and modified carbon nano tubes. The electric heating film can meet the requirements of compatibility with composite materials in the fields of fan blades, high-speed trains, airplanes and the like, and can also meet the urgent needs of high-performance anti-icing technology in the fields of fan blades, high-speed trains, airplanes and the like as a novel anti-icing material with high electric heating conversion efficiency and low anti-icing temperature.

Description

Technical Field

[0001] This invention relates to the field of membrane materials technology, and in particular to a carbon nanotube conductive ink, and also to an electric heating film prepared based on the carbon nanotube conductive ink. Background Technology

[0002] Ice buildup on the surfaces of wind turbine blades, high-speed trains, and aircraft poses significant safety hazards, making high-performance anti-icing and de-icing technologies crucial for ensuring their safe operation. However, traditional anti-icing and de-icing technologies such as mechanical de-icing, thermal anti-icing, and liquid anti-icing have many drawbacks. Mechanical de-icing suffers from high noise levels and structural fatigue; thermal anti-icing is complex and unsuitable for composite materials; and liquid anti-icing causes environmental pollution. Compared to these traditional technologies, electric heating anti-icing and de-icing technology offers advantages such as simple structure, high maintainability and reliability, low energy consumption, and environmental friendliness, leading to its increasingly widespread application.

[0003] Traditional electric heating anti-icing technology typically uses metal resistance wires as heating elements. However, metal heating elements have poor flexibility, making them prone to breakage during use, ultimately leading to system malfunction and inoperability. Furthermore, the wire-type heating of metal elements results in high temperatures in the heated areas and low temperatures in the unheated areas, requiring even higher temperatures to achieve the desired anti-icing effect. However, with the increasing use of composite materials in fields such as wind turbine blades, high-speed trains, and aircraft, composite materials have poorer high-temperature resistance and lower thermal conductivity compared to metals. The excessively high temperatures in the heated areas of metal heating elements and their poor compatibility with composite materials can severely impact the service performance of composite materials.

[0004] Therefore, there is an urgent need to develop new anti-icing and de-icing materials and technologies that are compatible with composite materials, have high electrothermal conversion efficiency, and low anti-icing temperature. Summary of the Invention

[0005] The main technical problem solved by this invention is to provide a carbon nanotube conductive ink, and also to provide an electric heating film based on the carbon nanotube conductive ink.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0007] In a first aspect, the present invention provides a carbon nanotube conductive ink, wherein the raw materials for preparing the carbon nanotube conductive ink include conductive functional particles, wherein the conductive functional particles include modified graphene and modified carbon nanotubes. Wherein, the modified graphene is graphene modified by a first polymer nanoparticle, and the modified carbon nanotube is carbon nanotube modified by a second polymer nanoparticle; the first polymer nanoparticle and the second polymer nanoparticle are both selected from at least one of polyaniline, polypyrrole, sulfonated polyphenylene acetylene, and 3-hexyl-substituted polythiophene; the first polymer nanoparticle and the second polymer nanoparticle may be the same or different.

[0008] In one embodiment of the present invention, the preparation process of the modified carbon nanotubes includes: mixing 1-20 parts by weight of carbon nanotubes and 1-40 parts by weight of a second polymer nanoparticle, followed by ball milling and dispersion to obtain modified carbon nanotubes. This preparation process uses mechanical grinding to uniformly coat the polymer nanoparticles onto the surface of the carbon nanotubes through π-π interactions. This method avoids the destruction of the intrinsic structure of carbon nanotubes caused by traditional chemical modification and effectively improves the dispersibility and interfacial bonding of carbon nanotubes in conductive inks.

[0009] Preferably, the ball milling dispersion is carried out in a ball mill at a rotation speed of 100-600 r / min, and the material-to-ball ratio is 1:(1-4).

[0010] Preferably, the carbon nanotubes are selected from single-walled carbon nanotubes and / or double-walled carbon nanotubes, and the median length of the carbon nanotubes is 1-200 μm.

[0011] In one embodiment of the present invention, the modified graphene preparation process includes: mixing 1-15 parts by weight of graphene and 1-30 parts by weight of a first polymer nanoparticle, followed by ball milling and dispersion to obtain modified graphene. This preparation process uses mechanical grinding to uniformly coat the polymer nanoparticles onto the graphene surface through π-π interactions. This method can effectively reduce the agglomeration of graphene in conductive inks and effectively improve the dispersibility and interfacial bonding of graphene in conductive inks.

[0012] Preferably, the ball milling dispersion is carried out in a ball mill at a rotation speed of 100-600 r / min, and the material-to-ball ratio is 1:(1-4).

[0013] Preferably, the graphene is selected from single-layer graphene and / or multi-layer graphene, with an average sheet diameter of 1-100 μm.

[0014] In one embodiment of the present invention, the mass ratio of the modified carbon nanotubes to the modified graphene is (2-8):(5-11).

[0015] As one embodiment of the present invention, the conductive functional particles further include conductive graphite, and the mass ratio of the conductive graphite to the modified graphene is (0.1-2):(5-11).

[0016] As one embodiment of the present invention, the conductive functional particles further include conductive carbon black, and the mass ratio of the conductive carbon black to the modified graphene is (1-5):(5-11).

[0017] In one embodiment of the present invention, the conductive functional particles account for 2%-30% of the mass of the raw materials for preparing the carbon nanotube conductive ink. Preferably, the conductive functional particles account for 5%-20% of the mass of the raw materials for preparing the carbon nanotube conductive ink; more preferably, the conductive functional particles account for 6%-16% of the mass of the raw materials for preparing the carbon nanotube conductive ink.

[0018] As one embodiment of the present invention, the raw materials for preparing the carbon nanotube conductive ink also include binders, solvents, additives, and auxiliary fillers.

[0019] In a preferred embodiment of the present invention, the binder accounts for 4%-30% of the mass of the raw materials for preparing the carbon nanotube conductive ink. More preferably, the binder accounts for 4%-15% of the mass of the raw materials for preparing the carbon nanotube conductive ink.

[0020] In a preferred embodiment of the present invention, the solvent accounts for 40%-93% by mass of the raw materials for preparing the carbon nanotube conductive ink. More preferably, the solvent accounts for 60%-90% by mass of the raw materials for preparing the carbon nanotube conductive ink.

[0021] In a preferred embodiment of the present invention, the additive accounts for 0.2%-5% by mass of the raw materials for preparing the carbon nanotube conductive ink. More preferably, the additive accounts for 1%-5% by mass of the raw materials for preparing the carbon nanotube conductive ink.

[0022] In a preferred embodiment of the present invention, the auxiliary filler accounts for 0.1%-5% of the mass percentage of the raw materials for preparing the carbon nanotube conductive ink. More preferably, the auxiliary filler accounts for 0.2%-2% of the mass percentage of the raw materials for preparing the carbon nanotube conductive ink.

[0023] As one embodiment of the present invention, the adhesive is selected from at least one of polyurethane, phenolic resin, epoxy resin, silicone resin, polyester resin, ternary vinyl acetate resin, bismaleimide resin, polyimide resin, and o-diallyl bisphenol A.

[0024] As one embodiment of the present invention, the solvent is selected from at least one of divalent esters, N,N-dimethylformamide, N-methylpyrrolidone, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, propylene glycol monomethyl ether, and ethylene glycol.

[0025] In one embodiment of the present invention, the additive is selected from at least one of dispersants, leveling agents, defoamers, plasticizers, and thickeners.

[0026] In one embodiment of the present invention, the auxiliary filler is selected from at least one of hollow glass microspheres, hexagonal boron nitride, nano silicon nitride, nano aluminum nitride, and nano silicon carbide.

[0027] Secondly, the present invention provides a method for preparing carbon nanotube conductive ink, comprising the following steps: S1: Conductive functional particles are prepared by mixing modified graphene, modified carbon nanotubes, conductive graphite, and conductive carbon black. S2: Mix the binder, solvent, additives, and auxiliary fillers to obtain a carrier dispersion; S3: Mix the conductive functional particles and the carrier dispersion, disperse them using a ball mill or grinding mill, and grind them to a fineness of ≤10μm to obtain carbon nanotube conductive ink.

[0028] In a preferred embodiment of the present invention, in step S3, when using a ball mill for dispersion, the ball mill operates at a speed of 300... Grinding and dispersing were carried out at a speed of 800 rad / min until the fineness was reduced to below 10 μm; the grinding balls were zirconia grinding balls with a diameter of 1-10 mm and the material-to-ball ratio was 1:(2-4).

[0029] In a preferred embodiment of the present invention, in step S3, when using a grinding mill for dispersion, a precision three-roll mill is used with a rotation speed ratio of 1:3:9, a rotation speed of 100-500 rpm, and a roller spacing of 3-5 μm for grinding and dispersion until the fineness is reduced to below 10 μm.

[0030] Thirdly, the present invention provides an application of carbon nanotube conductive ink in the preparation of an electric heating film, which can be used as an electric heating coating material for the electric heating film.

[0031] Fourthly, the present invention provides an electric heating film, including an electric heating coating, wherein the raw materials for preparing the electric heating coating include the carbon nanotube conductive ink described in the present invention.

[0032] In one embodiment of the present invention, the electroheating coating is applied to any one of the following substrates: fiber fabric, polymer film and sheet, and fiber-reinforced resin matrix composite material sheet; the electroheating coating is applied by any one of the following methods: screen printing, gravure printing, flexographic printing, inkjet printing, scraping, spraying, spin coating, dip coating, and bar coating.

[0033] In a preferred embodiment of the present invention, the fiber fabric is woven from one or more of the following: glass fiber, ceramic fiber, alumina fiber, quartz glass fiber, polyester fiber, polyimide fiber, poly(p-benzimidazole) fiber, and aramid fiber.

[0034] In a preferred embodiment of the present invention, the polymer film and sheet are selected from PET (polyterephthalate) film or sheet, PI (polyimide) film or sheet, PTFE (polytetrafluoroethylene) film or sheet, PVDF (polyvinylidene fluoride) film or sheet, PPS (polyphenylene sulfide) film or sheet, PEEK (polyether ether ketone) film or sheet, PEI (polyetherimide) film or sheet, PC (polycarbonate) film or sheet, and EVA (ethylene-vinyl acetate) film or sheet.

[0035] As a preferred embodiment of the present invention, the fiber-reinforced resin-based composite material sheet is selected from quartz fiber-reinforced composite materials, glass fiber-reinforced composite materials, carbon fiber-reinforced composite materials, aramid fiber-reinforced composite materials, etc., wherein the matrix resin of the composite material is selected from epoxy resin, bismaleimide resin, polyimide resin, cyanate ester resin, etc.

[0036] This invention provides a carbon nanotube conductive ink, wherein the conductive functional particles include modified graphene and modified carbon nanotubes. The graphene and carbon nanotubes are respectively non-covalently modified with polymer nanoparticles, effectively preventing the aggregation of nanomaterials and improving their dispersion stability in the conductive ink system. Further fabrication of an electrothermal film using this conductive ink containing modified graphene and modified carbon nanotubes showed a significant increase in the crosslinking density of the coated film and a reduction in film porosity and defects.

[0037] The carbon nanotube conductive ink provided by this invention further includes conductive graphite and / or conductive carbon black as conductive functional particles. By scientifically compounding several conductive materials of different dimensions—modified graphene, modified carbon nanotubes, conductive graphite, and / or conductive carbon black—a three-dimensional conductive network combining "points, lines, and surfaces" is constructed. This significantly improves the conductivity and resistance distribution uniformity of the conductive ink, ensuring uniform heating and effectively avoiding localized overheating. The electric heating film prepared using this conductive ink has advantages such as high electrothermal conversion efficiency, rapid heating rate, almost no thermal inertia, long corrosion resistance and lifespan, far-infrared radiation heating (high heat transfer efficiency), good heating uniformity, and low anti-icing temperature. In this invention, by adjusting the amount of each raw material used in the conductive ink preparation, the sheet resistance of the resulting electric heating film can be arbitrarily controlled within a wide range of 10-10000 Ω / sq.

[0038] The carbon nanotube conductive ink provided by this invention is suitable for a variety of coating processes, has a wide range of applicable substrates, and has low preparation cost.

[0039] The electric heating film provided by this invention can meet the requirements of good compatibility with composite materials in fields such as wind turbine blades, high-speed trains, and aircraft. As a new type of anti-icing and de-icing material with high electrothermal conversion efficiency and low anti-icing temperature, it can also meet the urgent needs of high-performance anti-icing and de-icing technology in fields such as wind turbine blades, high-speed trains, and aircraft.

[0040] The electrothermal film based on carbon nanotube conductive ink provided by this invention has the following beneficial effects: (1) Carbon nanomaterials such as modified graphene, modified carbon nanotubes, conductive carbon black and / or conductive graphite are used as raw materials for the preparation of conductive ink. Carbon nanomaterials have good electrical and thermal conductivity, high electrothermal conversion efficiency, and are easier to disperse through appropriate modification treatment, which is conducive to improving the stability and uniformity of conductive ink, and at the same time improves the storage time of conductive ink.

[0041] (2) The electrothermal conversion efficiency of the prepared electric heating film is higher than 90%, and it has a low anti-icing temperature and anti-icing power density.

[0042] (3) The electric heating film of the present invention has good compatibility with the composite material and can be integrated with the composite material to achieve integrated structure and function. While realizing the electric heating anti-icing function, it does not affect the service performance of the composite material. Attached Figure Description

[0043] Figure 1 This is a photograph of the electric heating film obtained in Embodiment 1 of the present invention; Figure 2 This is a scanning electron microscope image of the electroheating film prepared in Example 3 of the present invention; Figure 3 Here is a SEM image of the electric heating film prepared in Example 4 of this invention; Figure 4 This is an AFM image of the electric heating film prepared in Example 4 of the present invention. Detailed Implementation

[0044] The technical solution of the present invention will be described in detail below through specific embodiments. These embodiments are intended to further illustrate the content of the present invention, but are not intended to limit the scope of protection of the claims of the present invention.

[0045] Unless otherwise specified, the reagents or raw materials used in the following examples and comparative examples are all commercially available products that can be purchased.

[0046] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional experimental methods.

[0047] The following is information on the source of some of the raw materials involved: Carbon nanotubes: purchased from Shenzhen Feimo Technology Co., Ltd. Graphene: Purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd. Conductive carbon black: purchased from Lion Corporation of Japan, brand name ECP-600JD; Conductive graphite: purchased from Qingdao Yanhai Carbon Materials Co., Ltd., grade YKS-3; Polyaniline: Purchased from Guangdong Yuanfeng Chemical Technology Co., Ltd., with a purity of 99% and in a conductive state; Polypyrrole: purchased from Sigma-Aldrich, grade 577030; 3-Hexyl-substituted polythiophene: purchased from Hubei Biaoyue Biotechnology Development Co., Ltd.; Medium-temperature epoxy AC319 resin: purchased from AVIC Composite Materials Co., Ltd., grade AC319; High-temperature epoxy 1316 resin: purchased from AVIC Composite Materials Co., Ltd., grade 1316; 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; Phenolic resin: purchased from Jinan Shengquan Group, brand name CR-115; Ternary chloroacetic acid resin: purchased from Shexian Xinfeng Chemical Co., Ltd., brand name MVAH; Dispersant: Polyvinylpyrrolidone was used, purchased from Guangdong Yuemei Chemical Co., Ltd., brand name K90; 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.

[0048] Example 1 This embodiment provides a carbon nanotube conductive ink, which is prepared from the following raw materials: conductive functional particles, binder, solvent, additives, and auxiliary fillers. The conductive functional particles are made of modified graphene, modified carbon nanotubes, and conductive carbon black. The specific mass percentage composition of this carbon nanotube conductive ink is shown in Table 1.

[0049] Table 1 The method for preparing carbon nanotube conductive ink provided in this embodiment includes the following steps: S1: Conductive functional particles are prepared by mixing modified graphene, modified carbon nanotubes, and conductive carbon black. The modified carbon nanotubes were prepared by mixing 1 part by weight of carbon nanotubes and 2 parts by weight of polyaniline nanoparticles, and then grinding and dispersing them in a ball mill at a speed of 200 r / min with a material-to-ball ratio of 1:3 to obtain modified carbon nanotubes. The carbon nanotubes used were multi-walled carbon nanotubes with a median length of 20 μm. The modified graphene preparation process is as follows: 1 part by weight of graphene and 1 part by weight of polypyrrole nanoparticles are mixed and ground and dispersed in a ball mill at a speed of 300 r / min, with a material-to-ball ratio of 1:2, to obtain modified graphene; the graphene used is multilayer graphene with an average sheet diameter of 10 μm. S2: Mix the binder, solvent, additives, and auxiliary fillers to obtain a carrier dispersion; S3: The conductive functional particles and carrier dispersion are mixed and dispersed using a grinding mill. A precision three-roll mill is used at a rotation speed ratio of 1:3:9, a rotation speed of 300 rpm, and a roller spacing of 4 μm to grind and disperse the particles until the fineness is 6.0 μm, thus obtaining carbon nanotube conductive ink. The viscosity of this carbon nanotube conductive ink is 100 Pa·s.

[0050] An electric heating film was further prepared using the carbon nanotube conductive ink provided in this embodiment. The substrate of the electric heating film was quartz glass fiber fabric, and the film was prepared by screen printing. The specific screen printing process was as follows: the viscosity of the carbon nanotube conductive ink was 100 Pa·s, the squeegee hardness was 75 degrees, the squeegee angle was 75°, and a 200-mesh polyester screen was used. The specific operation was as follows: the quartz glass fiber fabric was placed under the screen, then the carbon nanotube conductive ink was poured onto the top of the screen and scraped evenly with a squeegee. The carbon nanotube conductive ink formed a printed wet film on the surface of the quartz glass fiber fabric through the mesh. After drying at 130°C for 60 minutes, the electric heating film was obtained. A photograph of the prepared electric heating film is shown below. Figure 1 As shown, from Figure 1 It can be seen that the electric heating film has high printing precision and clear lines.

[0051] Example 2 This embodiment provides a carbon nanotube conductive ink, which is prepared from the following raw materials: conductive functional particles, binder, solvent, additives, and auxiliary fillers. The conductive functional particles are made of modified graphene, modified carbon nanotubes, and conductive graphite. The specific mass percentage composition of this carbon nanotube conductive ink is shown in Table 2.

[0052] Table 2 The method for preparing carbon nanotube conductive ink provided in this embodiment includes the following steps: S1: Conductive functional particles are prepared by mixing modified graphene, modified carbon nanotubes and conductive graphite. The modified carbon nanotubes were prepared by mixing 2 parts by weight of carbon nanotubes and 1 part by weight of sulfonated polyphenylene acetylene nanoparticles, and then grinding and dispersing them in a ball mill at a speed of 300 r / min with a material-to-ball ratio of 1:2 to obtain modified carbon nanotubes. The carbon nanotubes used were multi-walled carbon nanotubes with a median length of 15 μm. The modified graphene preparation process is as follows: 1 part by weight of graphene and 2 parts by weight of 3-hexyl-substituted polythiophene nanoparticles are mixed and ground and dispersed in a ball mill at a speed of 100 r / min, with a material-to-ball ratio of 1:4, to obtain modified graphene; the graphene used is multilayer graphene with an average sheet diameter of 5 μm. S2: Mix the binder, solvent, additives, and auxiliary fillers to obtain a carrier dispersion; S3: The conductive functional particles and carrier dispersion were mixed and dispersed using a ball mill at a speed of 600 rad / min. Zirconia grinding balls with a diameter of 3 mm were used, with a particle-to-ball ratio of 1:4. The mixture was ground to a fineness of 5.0 μm to obtain carbon nanotube conductive ink. The viscosity of this carbon nanotube conductive ink was 100 mPa·s.

[0053] An electric heating film was further prepared using the carbon nanotube conductive ink provided in this embodiment. The substrate of the electric heating film was a glass fiber reinforced bismaleimide resin-based composite material plate. The electric heating film was prepared by spraying. The specific process was as follows: the viscosity of the carbon nanotube conductive ink was 100 mPa·s; an air spray gun was used; the spray gun pressure was 2.0 MPa; the spray gun moving speed was 0.5 m / s; the spray gun was 20 cm away from the substrate surface; the ambient temperature was controlled between 15-30℃; the air humidity was controlled between 40-70%; and after spraying, the film was dried at 160℃ for 40 min to obtain the electric heating film.

[0054] Example 3 This embodiment provides a carbon nanotube conductive ink, the raw materials for which are: conductive functional particles, binder, solvent, additives, and auxiliary fillers. The conductive functional particles are made of modified graphene, modified carbon nanotubes, conductive carbon black, and conductive graphite. The specific mass percentage composition of this carbon nanotube conductive ink is shown in Table 3.

[0055] Table 3 The method for preparing carbon nanotube conductive ink provided in this embodiment includes the following steps: S1: Conductive functional particles are prepared by mixing modified graphene, modified carbon nanotubes, conductive graphite, and conductive carbon black. The modified carbon nanotubes are prepared by mixing 1 part by weight of carbon nanotubes and 1 part by weight of polyaniline nanoparticles, and grinding and dispersing them in a ball mill at a speed of 200 r / min with a material-to-ball ratio of 1:3 to obtain modified carbon nanotubes. The carbon nanotubes used are single-walled carbon nanotubes with a median length of 10 μm. The modified graphene preparation process is as follows: 1 part by weight of graphene and 1 part by weight of polyaniline nanoparticles are mixed and ground and dispersed in a ball mill at a speed of 200 r / min, with a material-to-ball ratio of 1:3, to obtain modified graphene; the graphene used is multilayer graphene with an average sheet diameter of 8 μm. S2: Mix the binder, solvent, additives, and auxiliary fillers to obtain a carrier dispersion; S3: The conductive functional particles and carrier dispersion were mixed and dispersed using a ball mill at a speed of 500 rad / min. Zirconia grinding balls with a diameter of 2 mm were used, with a particle-to-ball ratio of 1:3. The mixture was ground to a fineness of 4 μm to obtain carbon nanotube conductive ink. The viscosity of this carbon nanotube conductive ink was 600 mPa·s.

[0056] An electric heating film was further prepared using the carbon nanotube conductive ink provided in this embodiment. The substrate of the electric heating film was quartz glass fiber fabric, and the film was prepared by dip-coating. Specifically, the carbon nanotube conductive ink had a viscosity of 600 mPa·s, a dip-coating time of 30 seconds, a pulling speed of 0.5 m / min, an ambient temperature controlled between 15-30℃, and an air humidity controlled between 40-70%. The dip-coated quartz glass fiber fabric was first pre-dried at 100℃ to reduce the solvent content and fluidity of the film layer, and then dried at 200℃ for 30 min to obtain the electric heating film. A scanning electron microscope image of the electric heating film is shown below. Figure 2 As shown, from Figure 2 As can be seen, the surface of the fiber fabric bundle is covered with an electric heating film. The electric heating film layer is very thin, and this preparation method can prepare a lightweight electric heating film.

[0057] Example 4 This embodiment provides a carbon nanotube conductive ink, which is prepared from the following raw materials: conductive functional particles, binder, solvent, additives, and auxiliary fillers. The conductive functional particles are made of modified graphene, modified carbon nanotubes, and conductive carbon black. The specific mass percentage composition of this carbon nanotube conductive ink is shown in Table 4.

[0058] Table 4 The method for preparing carbon nanotube conductive ink provided in this embodiment includes the following steps: S1: Conductive functional particles are prepared by mixing modified graphene, modified carbon nanotubes, and conductive carbon black. The modified carbon nanotubes were prepared by mixing 2 parts by weight of carbon nanotubes and 1 part by weight of polyaniline nanoparticles, and then grinding and dispersing them in a ball mill at a speed of 200 r / min with a material-to-ball ratio of 1:2 to obtain modified carbon nanotubes. The carbon nanotubes used were multi-walled carbon nanotubes with a median length of 30 μm. The modified graphene preparation process is as follows: 2 parts by weight of graphene and 1 part by weight of polyaniline nanoparticles are mixed and ground and dispersed in a ball mill at a speed of 200 r / min, with a material-to-ball ratio of 1:2, to obtain modified graphene; the graphene used is multilayer graphene with an average sheet diameter of 15 μm. S2: Mix the binder, solvent, additives, and auxiliary fillers to obtain a carrier dispersion; S3: The conductive functional particles and carrier dispersion were mixed and dispersed using a ball mill at a speed of 400 rad / min. Zirconia grinding balls with a diameter of 3 mm were used, with a particle-to-ball ratio of 1:3. The mixture was ground to a fineness of 5 μm to obtain carbon nanotube conductive ink. The viscosity of this carbon nanotube conductive ink was 800 mPa·s.

[0059] An electric heating film was further prepared using the carbon nanotube conductive ink provided in this embodiment. The substrate of the electric heating film was a PC (polycarbonate) sheet, and the film was prepared by spin coating. Specifically, the carbon nanotube conductive ink viscosity was 800 mPa·s, the spin coating speed was 1000 rpm, the spin coating time was 60 seconds, the ambient temperature was controlled between 15-30℃, the air humidity was controlled between 40-70%, and the film was dried at 120℃ for 15 min after spin coating to obtain the electric heating film. SEM images of this electric heating film are shown below. Figure 3 As shown, see AFM image. Figure 4 As shown in the figure, the surface of the electric heating film is uniform and flat, without obvious undulations, and the surface roughness is also low (Ra=0.72).

[0060] Comparative Example 1 This comparative example provides a carbon nanotube conductive ink, the only difference between its raw materials and those of Example 1 is that the conductive functional particles are made of graphene, carbon nanotubes and conductive carbon black, and the graphene and carbon nanotubes are not modified; the amount of each raw material is the same as that of Example 1, and the specific mass percentage composition is shown in Table 5.

[0061] Table 5 The method for preparing carbon nanotube conductive ink provided in this comparative example includes the following steps: S1: Graphene, carbon nanotubes and conductive carbon black are mixed to obtain conductive functional particles; S2: Mix the binder, solvent, additives, and auxiliary fillers to obtain a carrier dispersion; S3: The conductive functional particles and carrier dispersion are mixed and dispersed using a grinding mill. A precision three-roll mill is used at a speed ratio of 1:3:9, a rotation speed of 300 rpm, and a roller spacing of 4 μm to grind and disperse the particles until the fineness reaches 6.0 μm, thus obtaining carbon nanotube conductive ink. The viscosity of this carbon nanotube conductive ink is 102 Pa·s.

[0062] An electric heating film was further prepared using the carbon nanotube conductive ink provided in this comparative example. The substrate of the electric heating film was quartz glass fiber fabric, and the film was prepared by screen printing. The specific screen printing process was as follows: the viscosity of the carbon nanotube conductive ink was 102 Pa·s, the hardness of the squeegee was 75 degrees, the squeegee angle was 75°, and a 200-mesh polyester screen was used. The specific operation was as follows: the quartz glass fiber fabric was placed under the screen, then the carbon nanotube conductive ink was poured onto the top of the screen and scraped evenly with the squeegee. The carbon nanotube conductive ink formed a printed wet film on the surface of the quartz glass fiber fabric through the mesh, and then dried at 130°C for 60 minutes to obtain the electric heating film.

[0063] Performance testing The performance of the carbon nanotube conductive inks provided in Examples 1-4 and Comparative Example 1, and the electric heating films prepared using the carbon nanotube conductive inks, were tested. The specific test methods are as follows: Sheet resistance: According to YB / T "Determination of sheet resistance of graphene film by four-probe method", the sheet resistance of the electric heating film is measured by a four-probe resistance meter and the coefficient of variation is calculated. The sheet resistance coefficient of variation is used to characterize the sheet resistance uniformity. The smaller the value, the more uniform the electric heating film. Bending resistance change rate: The resistance change is measured and the resistance change rate is calculated after bending the electric heating film 180° around a round rod with a diameter of 8mm±0.8mm 10 times. Electrothermal conversion efficiency: The electric heating film was completely immersed in a container containing m kg of deionized water, ensuring no contact between the heating film and the container wall. The initial water temperature T0 was measured using a thermocouple. A voltage of 200V was applied to the electric heating film for heating, and the current I passing through the heating film was recorded. After 60 minutes, the water was thoroughly stirred to ensure uniform temperature throughout the container, and the water temperature was measured using a thermocouple until the temperature stopped changing. The heating time t and water temperature T1 at this point were recorded. The electrothermal conversion efficiency was calculated using the following formula: (1); In equation (1), 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). Heating rate and the difference between the highest and lowest temperatures: After placing the electric heating film in an environmental chamber at 23°C for 30 minutes, a voltage was applied to the workpiece to achieve a power density of 0.7 W / cm² for the electric heating film. 2 Thermocouples were used to measure the temperature, with six temperature measurement points set up. The difference between the highest and lowest temperatures was taken as the difference between the highest and lowest temperatures. The time required for the average temperature to rise from the ambient temperature to 80% of the steady-state temperature was taken as the heating time. The heating rate can be calculated using the following formula: (2); In equation (2), T is the heating rate (°C / s), Tmax is the average temperature of the steady state (°C), T0 is the ambient temperature (°C), and t is the heating time (s).

[0064] Interlaminar shear strength: The electrically heated film and the composite material were co-cured to prepare a sample, and then the interlaminar shear strength of the sample was tested according to the method specified in GB / T1450.1-2005 "Test Method for Interlaminar Shear Strength of Fiber Reinforced Plastics". Anti-icing performance test: Samples were prepared by co-curing the electric heating film and the composite material, and then 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.

[0065] The test data for the electric heating films provided in Example 1 and Comparative Example 1 are shown in Table 6 below: Table 6 The viscosity of the carbon nanotube conductive ink provided in Example 1 is 100 Pa·s, while the viscosity of the carbon nanotube conductive ink provided in Comparative Example 1 is 102 Pa·s. Compared to Example 1, Comparative Example 1 uses unmodified graphene and unmodified carbon nanotubes as conductive fillers, while other components, proportions, and preparation methods are completely consistent with Example 1. Viscosity test results show that the viscosity of the carbon nanotube conductive ink in Example 1, which uses modified graphene and modified carbon nanotubes, is basically the same as that in Comparative Example 1, indicating that the use of modified graphene and modified carbon nanotubes does not have a significant impact on the viscosity of the carbon nanotube conductive ink.

[0066] The sheet resistance test result of the electric heating film in Example 1 was 11.8 Ω / sq, which was higher than that of the electric heating film in Comparative Example 1 (9.8 Ω / sq), indicating that the modification of graphene and carbon nanotubes would slightly reduce the conductivity of graphene and carbon nanotubes.

[0067] The sheet resistance variation coefficient of the electroheating film in Example 1 was 2.8%, which was significantly lower than that of the electroheating film in Comparative Example 1 (6.5%). This indicates that the modification of graphene and carbon nanotubes can significantly improve the dispersibility of graphene and carbon nanotubes in conductive ink, thereby significantly improving the uniformity of the electroheating film.

[0068] The test result of the bending resistance change rate of the electric heating film in Example 1 was 0.4%, which was lower than the bending resistance change rate of 0.7% of the electric heating film in Comparative Example 1. This indicates that the modification of graphene and carbon nanotubes will improve the stability of the conductive structure in the electric heating film, and the internal conductive pathways are not easily broken or displaced.

[0069] The electrothermal conversion efficiency test result of the electric heating film in Example 1 was 91.2%, which was higher than that of the electric heating film in Comparative Example 1 (88.5%). This indicates that the modification of graphene and carbon nanotubes can slightly improve the electrothermal conversion efficiency, thereby slightly reducing the minimum anti-icing power density.

[0070] The test result of the difference between the highest and lowest temperatures of the electric heating film in Example 1 was 4℃, which was significantly lower than the difference between the highest and lowest temperatures of the electric heating film in Comparative Example 1 (10℃). This indicates that the modification of graphene and carbon nanotubes can greatly improve the uniformity of the electric heating film, thereby significantly improving the electric heating uniformity of the electric heating film.

[0071] The test data for the electric heating films provided in Examples 2-4 are shown in Table 7 below: Table 7 As can be seen from the data in Table 7, the electric heating film provided by the present invention has advantages such as good heating uniformity, fast heating rate, high electrothermal conversion efficiency, high stability of conductive structure, good compatibility with composite materials, and low anti-icing power density. It can meet the requirements of aviation, aerospace, wind power and other fields for high heating uniformity and high performance electric heating film.

[0072] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A carbon nanotube conductive ink, characterized in that, The raw materials for preparing carbon nanotube conductive ink include conductive functional particles, which include modified graphene and modified carbon nanotubes; wherein the modified graphene is graphene modified by a first polymer nanoparticle, and the modified carbon nanotube is carbon nanotube modified by a second polymer nanoparticle; the first polymer nanoparticle and the second polymer nanoparticle are both selected from at least one of polyaniline, polypyrrole, sulfonated polyphenyleneacetylene, and 3-hexyl-substituted polythiophene; the first polymer nanoparticle and the second polymer nanoparticle may be the same or different.

2. The carbon nanotube conductive ink according to claim 1, characterized in that, The mass ratio of the modified carbon nanotubes to the modified graphene is (2-8):(5-11).

3. The carbon nanotube conductive ink according to claim 1 or 2, characterized in that, The conductive functional particles further include conductive graphite, wherein the mass ratio of the conductive graphite to the modified graphene is (0.1-2):(5-11); and / or, The conductive functional particles also include conductive carbon black, and the mass ratio of the conductive carbon black to the modified graphene is (1-5):(5-11).

4. The carbon nanotube conductive ink according to claim 1, characterized in that, The conductive functional particles account for 2%-30% of the mass of the raw materials used in the preparation of the carbon nanotube conductive ink.

5. The carbon nanotube conductive ink according to claim 4, characterized in that, The raw materials for preparing the carbon nanotube conductive ink also include binders, solvents, additives, and auxiliary fillers; wherein, the binder accounts for 4%-30% of the mass of the raw materials for preparing the carbon nanotube conductive ink; the solvent accounts for 40%-93% of the mass of the raw materials for preparing the carbon nanotube conductive ink; the additives account for 0.2%-5% of the mass of the raw materials for preparing the carbon nanotube conductive ink; and the auxiliary fillers account for 0.1%-5% of the mass of the raw materials for preparing the carbon nanotube conductive ink.

6. The carbon nanotube conductive ink according to claim 5, characterized in that, The adhesive is selected from at least one of polyurethane, phenolic resin, epoxy resin, silicone resin, polyester resin, ternary vinyl acetate resin, bismaleimide resin, polyimide resin, and o-diallyl bisphenol A; and / or, The solvent is selected from at least one of divalent esters, N,N-dimethylformamide, N-methylpyrrolidone, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, propylene glycol monomethyl ether, and ethylene glycol; and / or, The additive is selected from at least one of dispersants, leveling agents, defoamers, plasticizers, and thickeners; and / or, The auxiliary filler is selected from at least one of hollow glass microspheres, hexagonal boron nitride, nano silicon nitride, nano aluminum nitride, and nano silicon carbide.

7. A method for preparing carbon nanotube conductive ink according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Conductive functional particles are prepared by mixing modified graphene, modified carbon nanotubes, conductive graphite, and conductive carbon black. S2: Mix the binder, solvent, additives, and auxiliary fillers to obtain a carrier dispersion; S3: Mix the conductive functional particles and the carrier dispersion, disperse them using a ball mill or grinding mill, and grind them to a fineness of ≤10μm to obtain carbon nanotube conductive ink.

8. The application of the carbon nanotube conductive ink according to any one of claims 1-6 in the preparation of an electric heating film.

9. An electric heating film, characterized in that, The invention includes an electrothermal coating, wherein the raw materials for preparing the electrothermal coating include the carbon nanotube conductive ink as described in any one of claims 1-6.

10. The electric heating film according to claim 9, characterized in that, The electroheating coating is applied to any one of the following substrates: fiber fabric, polymer film and sheet, and fiber-reinforced resin-based composite material sheet. The electroheating coating is applied using any one of the following methods: screen printing, gravure printing, flexographic printing, inkjet printing, scraping, spraying, spin coating, dip coating, and bar coating.

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