Water-soluble, high-temperature-resistant carbon nanotube resistance stabilizer, preparation method and application

Abstract

The application belongs to the technical field of preparation of structure and function integrated composite materials, and specifically discloses a water-soluble carbon nanotube resistance stabilizer, a preparation method and application. The carbon nanotube resistance stabilizer provided by the application has good water solubility and is environmentally friendly. The resistance stabilizer is used for pre-treating carbon nanomaterials, so that the high-temperature resistance of the materials can be improved, and the materials can match the co-curing conditions of high-temperature curing resin prepreg. Moreover, the cured stabilizer is insoluble in resin and water, has high high-temperature deformation resistance, and can maintain the stability of resistance. Meanwhile, the carbon nanotube film or coating after curing and bonding has high mechanical strength and good interface bonding with the resin matrix. The carbon nanotube resistance stabilizer provided by the application is suitable for preparing a conductive film layer co-cured with resin materials, and has good application prospect and high economic value.

Description

Technical Field

[0001] This invention belongs to the field of structural-functional integrated composite material preparation technology, specifically relating to a water-soluble carbon nanotube resistance stabilizer, its preparation method, and its application. Background Technology

[0002] Carbon nanotubes and other carbon nanomaterials have good electrical conductivity, a density much lower than that of metals, and a relatively high specific strength. In addition, carbon nanotubes also have a high aspect ratio, ranging from 100 to 10,000. When used as a conductive modifier, they also have a low percolation threshold, which can achieve high conductivity with low addition amounts. Therefore, they have attracted great attention from the academic and industrial communities.

[0003] Currently, carbon nanotubes have been widely used in conductive films, conductive polymers, and battery electrodes. However, the conductivity of carbon nanotubes distributed within materials is significantly affected by the spacing between them and the filler material. Conductive binders are necessary to effectively reduce the impact of external liquid flow and swelling on the spacing between carbon nanotubes, thereby maintaining resistance stability. Existing conductive binders generally use materials such as polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), polyacrylamide (PAMA), and polyvinylpyrrolidone (PVP). However, PVDF is an oil-soluble polymer, which can cause environmental pollution, while CMC and PPV have low heat distortion temperatures, making resistance stability even more difficult to control when combined with resins at high temperatures. Therefore, there is an urgent need to develop a water-soluble, high-temperature-resistant carbon nanotube resistance stabilizer. Summary of the Invention

[0004] The main technical problem addressed by this invention is that when carbon nanotube films are co-cured with resin prepregs at high temperatures, displacement easily occurs between the carbon nanotubes, leading to unstable and uncontrollable electrical resistance. To address this, this invention provides a novel water-soluble, high-temperature resistant carbon nanotube resistance stabilizer and its preparation method. This stabilizer primarily acts as a conductive binder for the carbon nanotubes in the co-cured carbon nanotube film, ensuring good resistance to heat deformation when the carbon nanotube film is laminated with high-viscosity resin at high molding temperatures, thereby maintaining the electrical resistance stability of the carbon nanotube film.

[0005] In addition, the present invention also provides an application of carbon nanotube resistance stabilizers.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, the raw materials for which are prepared include copolymers and tertiary amines;

[0008] The copolymer is formed by copolymerization of monomers A, B, and C.

[0009] The monomer A is selected from one or both of acrylic acid and methacrylic acid;

[0010] The monomer B is selected from one or both of acrylonitrile and methacrylonitrile;

[0011] The monomer C is selected from one or both of acrylamide and methacrylamide;

[0012] In molar quantities, monomer A: monomer B: monomer C = 40-60: 40-60: 0-4;

[0013] In molar quantities, monomer A: tertiary amine = 1: 0.2-2.

[0014] In a preferred embodiment of the present invention, the molar ratio of monomer A: monomer B: monomer C is 50-60: 40-50: 0-3.

[0015] In a preferred embodiment of the present invention, the tertiary amine is selected from one or more of pyridine, triethylamine, triethanolamine, dimethylethanolamine, dimethylisopropanolamine, and diethanolmonoisopropanolamine.

[0016] Specifically, when the tertiary amine is selected from one or both of pyridine and triethylamine, the molar ratio of monomer A to tertiary amine is 1:0.6-1.2.

[0017] Specifically, when the tertiary amine is selected from one or more of triethanolamine, dimethylethanolamine, dimethylisopropanolamine, and diethanolmonoisopropanolamine, the molar ratio of monomer A to tertiary amine is 1:0.2-1.2.

[0018] A method for preparing a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer includes the following steps:

[0019] The copolymer powder was mixed with a tertiary amine in water to obtain a carbon nanotube resistance stabilizer.

[0020] In a preferred embodiment of the present invention, the copolymer is prepared by polymerizing monomers A, B, and C under the action of an initiator to obtain the copolymer.

[0021] Specifically, the initiator is selected from one or more of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ADVN), benzoyl peroxide (BPO), etc.

[0022] Specifically, the polymerization reaction temperature is 40-60℃ and the time is 40-100h.

[0023] Applications of a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, including but not limited to any of the following:

[0024] (1) Used as a treatment agent for (modified) carbon nanotube films or coatings;

[0025] (2) Used as a co-dispersion modifier for carbon nanotube slurry.

[0026] In a preferred embodiment of the present invention, when the carbon nanotube resistance stabilizer is used as a treatment agent for (modified) carbon nanotube films or carbon nanotube coatings, the application includes:

[0027] Carbon nanotube resistance stabilizers (mixed with water or diluted with water) are prepared into an aqueous treatment solution;

[0028] The (modified) carbon nanotube film or carbon nanotube coating is immersed in an aqueous treatment solution, removed and dried, and then subjected to thermal imidization treatment (i.e., cyclization reaction and / or dehydration reaction) to obtain a carbon nanomaterial with stable electrical resistance.

[0029] Specifically, the mass percentage concentration of carbon nanotube resistance stabilizer in the aqueous treatment solution is 1%-16%.

[0030] Specifically, the temperature of the thermal imidization treatment is 160-240℃, and the time is 1-6h.

[0031] In a preferred embodiment of the present invention, when the carbon nanotube resistance stabilizer is used as a co-dispersion modifier for carbon nanotube slurry, the application includes:

[0032] Carbon nanotubes (mixed with water) are used to prepare an aqueous carbon nanotube slurry;

[0033] A co-dispersion is prepared by adding a carbon nanotube resistance stabilizer or an aqueous treatment solution containing a carbon nanotube resistance stabilizer to an aqueous carbon nanotube slurry. The carbon nanotube coating formed by the co-dispersion is then subjected to thermal imidization treatment (i.e., cyclization reaction and / or dehydration reaction) to obtain a resistance-stable carbon nanomaterial.

[0034] Specifically, the amount of carbon nanotube resistance stabilizer in the co-dispersion liquid is 30%-280% of the mass of carbon nanotubes.

[0035] Specifically, the temperature of the thermal imidization treatment is 160-240℃, and the time is 1-6h.

[0036] As a preferred embodiment of the present invention, the application further includes: co-curing resistively stable carbon nanomaterials with high-temperature curing resin prepregs under a molding process to obtain a resin composite material.

[0037] Specifically, the high-temperature curing resin prepreg is selected from one or more of epoxy resin prepreg, bismaleimide resin prepreg, etc.

[0038] The beneficial effects of this invention are:

[0039] The carbon nanotube resistance stabilizer provided by this invention exhibits good water solubility and is environmentally friendly. Pretreatment of carbon nanomaterials with this stabilizer improves their high-temperature resistance, allowing them to match the co-curing conditions of high-temperature curing resin prepregs. Furthermore, the cured stabilizer is insoluble in resin and water, possesses high resistance to high-temperature deformation, and can maintain stable resistance. Simultaneously, the cured and bonded carbon nanotube film or coating exhibits high mechanical strength and good interfacial bonding with the resin matrix. Therefore, the carbon nanotube resistance stabilizer provided by this invention is particularly suitable for preparing conductive films co-cured with resin materials. Detailed Implementation

[0040] 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.

[0041] Unless otherwise specified, the raw materials, reagents, equipment, etc. used in the following examples and comparative examples are all commercially available products.

[0042] Solution Description

[0043] This invention provides a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, its preparation method, and its applications. This resistance stabilizer is heat-resistant and has good water solubility; after curing, it is insoluble in resin and water and exhibits high resistance to high-temperature deformation. Furthermore, carbon nanotube films or coatings bonded with this resistance stabilizer have high mechanical strength and good interfacial bonding with the resin matrix, making it particularly suitable for conductive films co-cured with composite materials.

[0044] Current state of the technology and the significant advantages of this invention compared to the prior art:

[0045] (1) In the prior art, ionic polymers such as PVDF, which is soluble in NMP, and sodium carboxymethyl cellulose, which is soluble in water, are often used as conductive binders. The former is prone to causing environmental pollution and is expensive, while the latter has poor water resistance. The carbon nanotube resistance stabilizer (i.e., conductive binder) prepared in this invention is an ionic polymer with good water solubility. It has good mixing stability when mixed with water-dispersed carbon nanotube slurry. It can be converted into nonionic polymethylimide at high temperature and has good water resistance. Compared with the prior art, the conductive bonding effect is significantly better.

[0046] (2) In the prior art, water-soluble binders such as sodium carboxymethyl cellulose, polyacrylamide, polyacrylate, and polyvinyl alcohol have low temperature resistance, are prone to decomposition at high temperatures, and are prone to heat deformation, making them difficult to match with the hot pressing process of high-temperature resistant composite materials at 150°C and above. However, the poly(meth)acrylimide converted from the resistance stabilizer of the present invention has a heat distortion temperature of 200°C and above, which can match the co-curing process of high-temperature epoxy resin prepreg system and bismaleimide resin prepreg system.

[0047] (3) In addition, the water-soluble resistance stabilizer prepared by the present invention has a relatively excessive amount of carboxyl groups, which can form a good interface bond with the resin composite material after curing.

[0048] In order to achieve the purpose of the invention, the following design and technical improvements have been creatively made:

[0049] (1) In order to make the water-soluble resistance stabilizer meet the requirements of water solubility before bonding and high water resistance after bonding, unlike the existing carbon nanotube adhesive materials, this invention innovatively designs a resistance stabilizer with a special composition and structure. That is, it uses the quaternary ammonium salt of the copolymer of acrylic acid or methacrylic acid, acrylonitrile or methacrylonitrile as the precursor (as shown in Formula I below, wherein the copolymer is obtained by copolymerization of methacrylic acid, methacrylonitrile, and acrylamide initiated by an initiator, and the tertiary amine is triethylamine) to achieve water solubility, and uses poly(meth)acrylimide as the final product to achieve high water resistance, thereby distinguishing it from the existing conductive adhesive system and achieving the unity of environmental protection and high water resistance.

[0050]

[0051] (2) To achieve high heat resistance of the material, especially to meet the co-curing requirements of high-temperature resistant epoxy resin and bismaleimide resin (curing temperatures of 180℃ and 200℃ respectively), the monomers and their molar amounts need to be controlled as follows: acrylic acid (AA) or methacrylic acid (MAA) 40-60 parts, acrylonitrile (AN) or methacrylonitrile (MAN) 40-60 parts, acrylamide (AM) or methacrylamide (MAM) 0-4 parts. When this range is exceeded, the glass transition temperature of the copolymer thermal imidization product is lower than 200℃, and the resistance fluctuation during the resin material molding process becomes significantly larger, as shown in Table 1 below. The table shows the resistance change rate before and after co-curing of a typical carbon nanotube conductive film coated with quartz fiber fabric reinforced epoxy resin prepreg QW120 / 1316. The surface resistance of the carbon nanotube film used is 500Ω / sq, and the curing temperature of the resin prepreg is 180℃. When the resistance stabilizer T g Below the curing temperature, the resistivity change rate of the carbon nanotube film increases significantly and is difficult to control.

[0052] Table 1. Resistance change rate of carbon nanotube films co-cured with QW120 / 1316 before and after curing.

[0053]

[0054] (3) In order to achieve the water solubility of the material, when the tertiary amine is selected as pyridine, triethylamine, triethanolamine, dimethylethanolamine, dimethylisopropanolamine, or diethanolmonoisopropanolamine, its amount needs to be controlled to be 0.2-1.2 of the number of moles of acrylic acid or methacrylic acid units. Its solubility is shown in Table 2 below.

[0055] Table 2. Solubility of copolymer quaternary ammonium salts in water

[0056]

[0057] (4) Experiments have shown that carbon nanomaterials treated with a homogeneous solution (i.e., an aqueous treatment solution containing a resistance stabilizer) exhibit better resistance stability. This invention has specifically optimized the raw materials and their dosage. When the solution is an emulsion, the resistance change rate is more prone to fluctuations, making it difficult to control, and the batch-to-batch stability is poor. Based on the solubility test structure in Table 2, it can be seen that when the tertiary amine is pyridine or triethylamine, the preferred dosage is 0.6-1.2 times the molar number of acrylic acid or methacrylic acid units; when the tertiary amine is triethanolamine, dimethylethanolamine, dimethylisopropanolamine, or diethanolmonoisopropanolamine, the preferred dosage is 0.4-1.2 times the molar number of acrylic acid or methacrylic acid units.

[0058] (5) To address the need for co-curing with high-temperature resistant epoxy resin or bismaleimide resin prepregs, this invention investigated the influence of copolymer monomer composition on the interlaminar shear strength of co-cured composite materials, as shown in Table 3 below. Using QW120 / 1316 as the research system, the monomer composition of the copolymer, further optimized through experimental results, was (in molar parts): 50-60 parts acrylic acid or methacrylic acid, 40-50 parts acrylonitrile or methacrylonitrile, and 0-3 parts acrylamide or methacrylamide. This treatment resulted in better interfacial bonding between the carbon nanotube film or coating and the resin composite material.

[0059] Table 3. Resistance change rate of carbon nanotube films co-cured with QW120 / 1316 before and after curing.

[0060]

[0061] (6) Application of resistance stabilizers

[0062] 6a) The aqueous carbon nanotube resistance stabilizer provided by this invention is generally dissolved in water, and then the carbon nanotube membrane is treated with this water-soluble resistance stabilizer. However, the mass percentage concentration of the resistance stabilizer in the aqueous treatment solution needs to be controlled between 1% and 16%. When the concentration is below 1%, the resistance of the carbon nanotube membrane after co-curing with the resin prepreg will change abruptly, with the resistance change rate significantly increasing from approximately 85%-95% to 140%-200%. When the concentration is above 16%, the resistance after treatment will increase significantly, especially for carbon nanotube membranes with high resistance, where the resistance after treatment may even exceed 100%. Therefore, it is necessary to control the mass percentage concentration of the resistance stabilizer in the aqueous treatment solution.

[0063] 6b) The aqueous carbon nanotube resistance stabilizer provided by this invention can also be dissolved in aqueous carbon nanotube slurry and used together with carbon nanotubes. However, the amount of the resistance stabilizer should be 30%-280% of the mass of the carbon nanotubes. When it is less than 30%, the resistance stability deteriorates, and the resistance change rate after co-curing the carbon nanotube film and resin prepreg increases to 150%-300%. When the amount is higher than 280%, the resistance of the carbon nanotubes will increase significantly, and the amount of carbon nanotube slurry needed to prepare a carbon nanotube film with the same resistance will increase by more than three times. Therefore, when the resistance stabilizer is used in conjunction with the carbon nanotube slurry, its content relative to the carbon nanotubes needs to be controlled.

[0064] Example 1

[0065] This embodiment provides a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, the raw materials for which include copolymers and tertiary amines;

[0066] The copolymer is formed by copolymerization of monomers A, B, and C.

[0067] The monomer A is methacrylic acid;

[0068] The monomer B is methacrylonitrile;

[0069] The monomer C is acrylamide;

[0070] The tertiary amine is triethylamine;

[0071] In molar quantities, monomer A: monomer B: monomer C = 40:40:2;

[0072] In molar quantities, monomer A: tertiary amine = 1:1.

[0073] This embodiment provides a method for preparing and applying a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, including the following steps:

[0074] (1-1) Take 86.1 g (1 mol) of methacrylic acid, 67.1 g (1 mol) of methacrylonitrile, 0.05 mol of acrylamide, and 0.78 g of azobisisobutyronitrile (AIBN) as initiator. Mix the above four substances, stir and dissolve them evenly, then place them in a flask, seal it, and react it in a 40°C water bath for 72 h to obtain a nearly colorless transparent solid copolymer.

[0075] (1-2) Take out the copolymer obtained in (1-1) above, crush it into powder, and sieve it through a 50-mesh sieve to obtain a white powder; take 1700g of water and 101.2g (1mol) of triethylamine, mix them evenly, and then add the white powder to the above mixed liquid, stir to dissolve, and obtain the treatment solution of water-based carbon nanotube resistance stabilizer PAMNM100-100;

[0076] (1-3) Take a piece of barkey paper with a surface resistance R1 of 75Ω, immerse it in the above treatment solution, then take it out and heat it to 160℃ for 5 hours to allow the resistance stabilizer to be fully imidized.

[0077] (1-4) The treated bacillus paper is co-laid with quartz fiber fabric-reinforced epoxy resin prepreg QW120 / 1316, and the layup sequence is [0|90]. 20 The treated bacillus paper was placed in the middle layer and then cured using the QW120 / 1316 molding process at a curing pressure of 0.6 MPa. After curing, it was cooled to below 60°C to obtain the composite material board. The resistance R2 of the co-cured bacillus paper was measured.

[0078] Simultaneously, untreated buckypaper is co-laid with quartz fiber fabric-reinforced epoxy resin prepreg QW120 / 1316, with the layup sequence being [0|90]. 20 Untreated bacillus paper was placed in the middle layer and then cured using the QW120 / 1316 molding process at a curing pressure of 0.6 MPa. After curing, it was cooled to below 60°C to obtain the composite material board. The resistance R3 of the co-cured bacillus paper was measured.

[0079] Experimental method: While detecting the resistance of the co-cured bacillus paper, the interlaminar shear strength of the composite material board was tested by processing samples separately.

[0080] Experimental Results: The copolymer powder obtained in (1-1) dissolved well in the mixed solvent of water and triethylamine in (1-2), forming a homogeneous and transparent solution. After treatment, the R2 / R1 ratio of the bacillus paper was 0.96, while the R3 / R1 ratio was 1.58, indicating that the resistance stabilizer significantly improved the resistance stability of the bacillus paper. As for the interlaminar shear strength of the composite board, the treated composite board had a strength of 83 MPa, while the untreated composite board had a strength of 85 MPa, both slightly lower than the 91.5 MPa of conventional QW120 / 1316.

[0081] In other embodiments of the present invention, the triethylamine used in (1-2) can be replaced with pyridine, or triethanolamine, dimethylisopropanolamine, etc., and the amount used is 1 mol, which basically does not affect the properties and performance of the material.

[0082] Example 2

[0083] This embodiment provides a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, its preparation method, and its application, including the following steps:

[0084] (2-1) Take 94.7g (1.1mol) of methacrylic acid, 67.1g (1mol) of methacrylonitrile, 2.1g (0.03mol) of acrylamide, and 0.82g of azobisisobutyronitrile (AIBN) as initiator. Mix the above four substances, stir and dissolve them evenly, then place them in a flask, seal it, and react it in a 40℃ water bath for 72h to obtain a nearly colorless transparent solid copolymer.

[0085] (2-2) Take out the copolymer obtained in (2-1) above, crush it into powder, and sieve it through a 50-mesh sieve to obtain a white powder; take 4000g of water and 47.5g (0.66mol) of pyridine, mix them evenly, and then add the white powder to the above mixed liquid, stir to dissolve, and obtain the treatment solution of water-based carbon nanotube resistance stabilizer PAMNM110-066;

[0086] (2-3) Disperse carbon nanotubes in water to form a homogeneous solution with a concentration of 1.6 wt%. Then coat the solution onto aramid fabric to obtain a carbon nanotube conductive film attached to the aramid fabric with a surface resistance R1 of 500 Ω. Immerse the film in the above treatment solution, then remove it and heat it to 180°C for 3 hours to allow the resistance stabilizer to be fully imidized.

[0087] (2-4) The carbon nanotube conductive film attached to the aramid fabric is co-laid with quartz fiber fabric reinforced epoxy resin prepreg QW120 / 1316, and the layup sequence is [0|90]. 20A carbon nanotube conductive film was placed in the intermediate layer and then cured using the QW120 / 1316 molding process at a curing pressure of 0.6 MPa. After curing, the film was cooled to below 60°C to obtain a composite material plate. The resistance R2 of the co-cured carbon nanotube film was measured.

[0088] Simultaneously, an untreated carbon nanotube conductive film attached to the aramid fabric is co-laid with a quartz fiber fabric-reinforced epoxy resin prepreg QW120 / 1316, with the layup sequence being [0|90]. 20 An untreated carbon nanotube conductive film was placed in the intermediate layer and then cured using a QW120 / 1316 molding process at a curing pressure of 0.6 MPa. After curing, the film was cooled to below 60°C to obtain a composite material plate. The resistance R3 of the co-cured carbon nanotube film was measured.

[0089] Experimental method: While detecting the resistance of the co-cured carbon nanotube film, the interlaminar shear strength of the composite material plate was tested by processing samples separately.

[0090] Experimental Results: The copolymer powder obtained in (2-1) dissolved well in the mixed solvent of water and pyridine in (2-2), forming a homogeneous and transparent solution. After treatment, the R2 / R1 ratio of the carbon nanotube conductive film was 0.94, while the R3 / R1 ratio was 6.94, indicating that the resistance stabilizer significantly improved the resistance stability of the carbon nanotube conductive film. As for the interlaminar shear strength of the composite plate, the treated composite plate had a strength of 87 MPa, while the untreated composite plate had a strength of 75 MPa, indicating that the resistance stabilizer with more carboxyl groups can also improve the interlaminar adhesion.

[0091] Example 3

[0092] This embodiment provides a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, its preparation method, and its application, including the following steps:

[0093] (3-1) Take 99g (1.15mol) of methacrylic acid, 53.1g (1mol) of acrylonitrile, 0.01mol of acrylamide, 0.78g of initiator azobisisobutyronitrile (ADVN), and 250g of acetone. Mix the above five substances, stir and dissolve them evenly, then place them in a flask, seal it, and react it in a 50℃ water bath for 96h to obtain a nearly colorless and transparent viscous solution.

[0094] (3-2) Add 0.575 mol of triethanolamine to the viscous solution obtained in (3-1) above, stir, and a white solid precipitate is obtained. Remove acetone by heating and dry in a vacuum oven to obtain a white solid. Then, pulverize the white solid and pass it through a 20-mesh sieve to obtain a white powder, which is the water-based carbon nanotube resistance stabilizer PAANM115-050.

[0095] (3-3) Carbon nanotubes were dispersed in water to form a dispersion with a concentration of 2.0 wt%. The resistance stabilizer obtained in (3-2) was added to the dispersion under ultrasonic treatment to prepare four co-dispersions with concentrations of 0.6 wt%, 1.0 wt%, 2.0 wt%, and 3.0 wt%. The co-dispersions were brushed onto glass cloth, and the resistance was controlled to be 300 Ω. The coated glass cloth was then heated to 180 °C in an oven and kept for 3 hours to allow the resistance stabilizer to be fully imidized.

[0096] (3-4) The glass cloth treated with different concentrations of co-dispersion liquid and the attached carbon nanotube membrane are co-laid with quartz fiber fabric reinforced epoxy resin prepreg QW120 / 1316, and the layup sequence is [0|90]. 20 A glass cloth-carbon nanotube film is placed in the middle layer and then cured under the molding process of QW120 / 1316 with a curing pressure of 0.6MPa. After curing, it is cooled to below 60℃ to obtain a composite material board.

[0097] Experimental methods: The resistance R2 of the co-cured carbon nanotube film was measured, and the interlaminar shear strength of the composite material plate was tested by processing the samples separately.

[0098] Experimental results: The co-dispersion obtained in (3-3) above has good stability and can be stored for a long time. After treatment, the resistance change rate of the conductive film obtained with different concentrations of resistance stabilizer and the interlaminar shear strength of the composite material plate are shown in Table 4 below.

[0099] Table 4. Resistance change rate of conductive film and interlaminar shear strength of composite material plate

[0100] resistance stabilizer concentration 0.6wt% 1.0wt% 2.0wt% 3.0wt% <![CDATA[R2 / R1]]> 1.15 1.01 0.95 0.94 Interlaminar shear strength (MPa) 81.5 82.1 84.3 85.2

[0101] In other embodiments of the present invention, the triethanolamine used in (3-2) can be replaced with dimethylisopropanolamine, diethanol monoisopropanolamine, etc., and the amount used is 0.575 mol, which basically does not affect the properties and performance of the material.

[0102] Example 4

[0103] This embodiment provides a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, its preparation method, and its application, including the following steps:

[0104] (4-1) Take 77.5g (0.9mol) of methacrylic acid, 58.4g (1.1mol) of acrylonitrile, 2.84g (0.04mol) of acrylamide, and 1.39g of azobisisobutyronitrile (AIBN) as initiator. Mix the above four substances, stir and dissolve them evenly, then place them in a flask, seal it, and react it in a 40℃ water bath for 96h to obtain a nearly colorless transparent solid copolymer.

[0105] (4-2) Take out the copolymer obtained in (4-1) above, crush it into powder, and sieve it through a 50-mesh sieve to obtain a white powder; take 5000g of water and 114g (0.7mol) of diethanol monoisopropanolamine, mix them evenly, and then add the white powder to the above mixed liquid, stir to dissolve, and obtain the treatment solution of water-based carbon nanotube resistance stabilizer PANM082-070 (mass percentage concentration of 2.64wt%).

[0106] (4-3) Take a piece of barkey paper with a surface resistance R1 of 75Ω, immerse it in the above treatment solution, then take it out, heat it to 240℃ and keep it for 1 hour to fully imidize the resistance stabilizer, and then vacuum remove any possible residual tertiary amine.

[0107] (4-4) The treated buckypaper is co-laid with quartz fiber fabric-reinforced epoxy resin prepreg QW120 / 1316, and the layup sequence is [0|90]. 20 The treated bacillus paper is placed in the middle layer and then cured under the QW120 / 1316 molding process with a curing pressure of 0.6MPa. After curing, it is cooled to below 60℃ to obtain the composite material board.

[0108] Experimental methods: The resistance R2 of the co-cured bacillus paper was measured, and the interlaminar shear strength of the composite material plate was tested after processing the sample.

[0109] Experimental results: The copolymer powder obtained in (4-1) dissolved well in the mixed solvent of water and diethanolamine in (4-2), forming a homogeneous and transparent solution. After treatment, the R2 / R1 ratio of the bacillus paper was 0.97, indicating that the resistance stabilizer significantly improved the resistance curing stability of the bacillus paper. As for the interlaminar shear strength of the composite board, the treated composite board had a strength of 79.5 MPa.

[0110] In other embodiments of the present invention, the diethanol monoisopropanolamine used in (4-2) can be replaced with triethanolamine, dimethylisopropanolamine, etc., and the amount used is 0.7 mol, which basically does not affect the properties and performance of the material.

[0111] Example 5

[0112] This embodiment provides a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, its preparation method, and its application, including the following steps:

[0113] (5-1) Take 103.3g (1.2mol) of methacrylic acid, 59g (0.88mol) of methacrylonitrile, 4.26g (0.06mol) of acrylamide, 0.42g of initiator azobisisoheptanenitrile (ADVN) and 0.42g of benzoyl peroxide (BPO) (total 0.84g), and 250g of acetone. Mix the above five substances, stir and dissolve them evenly, then place them in a flask, seal it, and react it in a 50℃ water bath for 96h to obtain a nearly colorless and transparent viscous solution.

[0114] (5-2) Add 80.2 g (0.9 mol) of dimethylethanolamine to the viscous solution obtained in (5-1) above, stir, and a white solid precipitate is obtained. Filter and heat to remove acetone, and dry in a vacuum oven to obtain a white solid. Then, pulverize the white solid and pass it through a 20-mesh sieve to obtain a white powder, which is the water-based carbon nanotube resistance stabilizer PAANM136-075.

[0115] (5-3) Carbon nanotubes were dispersed in water to form a dispersion with a concentration of 1.5 wt%. The above-mentioned resistance stabilizer was added to the dispersion under ultrasonic treatment to prepare two co-dispersions with concentrations of 1.5 wt% and 3.0 wt%. The above co-dispersions were brushed onto glass cloth, and the resistance was controlled to be 300 Ω. The coated glass cloth was then heated to 200 ℃ in an oven and kept for 3 hours to allow the resistance stabilizer to be fully imidized.

[0116] (5-4) The glass cloth and attached carbon nanotube membrane treated with co-dispersion solutions of different concentrations were co-laid with quartz fiber fabric reinforced bismaleimide resin prepreg QW280 / 5429, and the layup sequence was [0|90]. 20 A glass cloth-carbon nanotube film is placed in the middle layer and then cured using the QW280 / 5429 molding process. The curing pressure is 0.6MPa and the curing temperature is 200℃. After curing, the film is cooled to below 60℃ to obtain a composite material board.

[0117] Experimental methods: The resistance R2 of the co-cured carbon nanotube film was measured, and the interlaminar shear strength of the composite material plate was tested by processing the samples separately.

[0118] Experimental Results: The R2 / R1 ratios of the obtained composite plates corresponding to the two co-dispersions were 1.15 and 1.01, respectively, while the resistivity change rate of the carbon nanotube film without the added resistance stabilizer was 2.81, indicating that the resistance stabilizer significantly improved the curing resistance stability of the carbon nanotube film. As for the interlaminar shear strength of the composite plates, the values ​​for the two co-dispersions were 85.4 MPa and 89.2 MPa, respectively, while the value for the composite plate without the added resistance stabilizer was 85.1 MPa.

[0119] 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. The application of a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, characterized in that: When carbon nanotube resistance stabilizers are used as treatment agents for carbon nanotube films or carbon nanotube coatings, the applications include: Carbon nanotube resistance stabilizer was formulated into an aqueous treatment solution; The carbon nanotube film or carbon nanotube coating is immersed in an aqueous treatment solution, taken out and dried, and then subjected to thermal imidization treatment to obtain a carbon nanomaterial with stable resistance. The mass percentage concentration of carbon nanotube resistance stabilizer in the aqueous treatment solution is 1%-16%. The thermal imidization treatment is performed at a temperature of 160-240℃ for 1-6 hours. The raw materials for preparing the carbon nanotube resistance stabilizer include copolymers and tertiary amines; The copolymer is formed by copolymerization of monomers A, B, and C. The monomer A is selected from one or both of acrylic acid and methacrylic acid; The monomer B is selected from one or both of acrylonitrile and methacrylonitrile; The monomer C is selected from one or both of acrylamide and methacrylamide; In molar quantities, monomer A: monomer B: monomer C = 40-60: 40-60: 0-4; In molar amounts, monomer A: tertiary amine = 1: 0.2-2; The tertiary amine is selected from one or more of pyridine, triethylamine, triethanolamine, dimethylethanolamine, dimethylisopropanolamine, and diethanolmonoisopropanolamine.

2. The application of a water-soluble, high-temperature resistant carbon nanotube resistance stabilizer, characterized in that: When carbon nanotube resistance stabilizers are used as co-dispersion modifiers for carbon nanotube slurries, the applications include: Carbon nanotubes are prepared into an aqueous carbon nanotube slurry; A co-dispersion is prepared by adding a carbon nanotube resistance stabilizer or an aqueous treatment solution containing a carbon nanotube resistance stabilizer to an aqueous carbon nanotube slurry. The carbon nanotube coating formed by the co-dispersion is then subjected to thermal imidization treatment to obtain a resistance-stable carbon nanomaterial. The amount of carbon nanotube resistance stabilizer in the co-dispersion is 30%-280% of the mass of carbon nanotubes; The thermal imidization treatment is performed at a temperature of 160-240℃ for 1-6 hours. The raw materials for preparing the carbon nanotube resistance stabilizer include copolymers and tertiary amines; The copolymer is formed by copolymerization of monomers A, B, and C. The monomer A is selected from one or both of acrylic acid and methacrylic acid; The monomer B is selected from one or both of acrylonitrile and methacrylonitrile; The monomer C is selected from one or both of acrylamide and methacrylamide; In molar quantities, monomer A: monomer B: monomer C = 40-60: 40-60: 0-4; In molar amounts, monomer A: tertiary amine = 1: 0.2-2; The tertiary amine is selected from one or more of pyridine, triethylamine, triethanolamine, dimethylethanolamine, dimethylisopropanolamine, and diethanolmonoisopropanolamine.

3. The application according to claim 2, characterized in that: The application also includes: co-curing resistively stable carbon nanomaterials with high-temperature curing resin prepregs under a molding process to obtain resin composite materials.

4. The application according to claim 3, characterized in that: The high-temperature curing resin prepreg is selected from one or two of epoxy resin prepreg and bismaleimide resin prepreg.

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