Flexible electric heating material, preparation method and application thereof

Abstract

The application relates to a flexible electric heating material and a preparation method and application thereof, and belongs to the technical field of electric heating materials.The preparation method comprises the following steps: S1, vacuum plasma treatment is carried out on a fiber fabric to obtain an activated fiber fabric; S2, an organic silicon compound is grafted on the surface of the activated fiber fabric to obtain a first modified fiber fabric; S3, the first modified fiber fabric is placed in a mixed solution containing an initiator and a polymerization monomer to carry out a polymerization reaction and grow a polymer brush, so that a second modified fiber fabric is obtained; S4, the second modified fiber fabric is placed in an (NH4)2PdCl4 solution to carry out ion exchange, so that a third modified fiber fabric is obtained; and S5, the third modified fiber fabric is placed in a chemical plating solution to deposit a metal layer, so that the flexible electric heating material is obtained.The flexible electric heating material prepared by the application has high strength and adjustable heating efficiency, and can maintain excellent mechanical properties and heating performance in a complex environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric heating materials, in particular to a flexible electric heating material and a preparation method and application thereof. BACKGROUND

[0002] In the field of aerospace, shape memory polymer composites are widely used in driving devices of deployable structures. The traditional driving method is to adhere an electric heating film to the surface and drive deployment by remote heating. However, the surface-adhered electric heating film is prone to adhesion failure due to high temperature during use, especially in extreme environments, resulting in debonding phenomenon, which leads to unstable operation of the driving device, and even possible failure. This poses a major challenge to the reliability and safety of aerospace equipment.

[0003] With the development of intelligent technology, electric heating materials have been widely used in many fields, especially flexible electric heating films, which have attracted much attention due to their lightness, flexibility, and good folding resistance. However, the existing flexible electric heating film technology has many shortcomings, such as poor film layer adhesion, low electric heating conversion efficiency, uneven distribution of heating materials, etc. This is mainly due to the insufficient adhesion of conductive paste on the substrate, and the conductive particles are coated in the resin, which reduces the electric-thermal conversion efficiency and easily causes local overheating. In addition, the electric heating film often has uneven heating, even power attenuation and open circuit during bending and use, which seriously affects its service life and reliability. SUMMARY

[0004] In view of one or more technical problems in the prior art, the present application provides a flexible electric heating material and a preparation method and application thereof. The flexible electric heating material prepared by the present application has high strength and adjustable heating efficiency, and the fiber fabric and the metal layer (heating layer) are tightly combined, which has excellent mechanical properties and reliability, and can maintain excellent mechanical properties and heating properties in complex environments.

[0005] In a first aspect, the present application provides a preparation method of a flexible electric heating material, which comprises the following steps:

[0006] S1. subjecting a fiber fabric to vacuum plasma treatment to obtain an activated fiber fabric;

[0007] S2. grafting an organosilicon compound on the surface of the activated fiber fabric to obtain a first modified fiber fabric; the organosilicon compound is a silane coupling agent containing a carbon-carbon double bond;

[0008] S3. placing the first modified fiber fabric in a mixed solution containing an initiator and a polymerization monomer to perform a polymerization reaction and grow a polymer brush to obtain a second modified fiber fabric; the polymerization monomer is a quaternary ammonium salt containing a carbon-carbon double bond;

[0009] S4. placing the second modified fiber fabric into (NH4)2PdCl4 solution to perform ion exchange, to obtain a third modified fiber fabric;

[0010] S5. placing the third modified fiber fabric into a chemical plating solution to perform metal layer deposition, to obtain a flexible electric heating material.

[0011] Preferably, the fibers in the fiber fabric are one or more of carbon fiber, glass fiber, Kevlar fiber, polyester fiber;

[0012] The silane coupling agent containing carbon-carbon double bond is 3-(trimethoxysilyl)propyl methacrylate;

[0013] The quaternary ammonium salt containing carbon-carbon double bond is methacryloyloxyethyl trimethyl ammonium chloride; and / or

[0014] The initiator is one or more of peroxide initiator, azo initiator.

[0015] Preferably, the time of the vacuum plasma treatment is not less than 30 min.

[0016] Preferably, the surface of the activated fiber fabric is grafted with an organosilicon compound, which comprises:

[0017] placing the activated fiber fabric into an organosilicon compound solution and reacting for 1-2 h; the organosilicon compound solution is obtained by mixing an organosilicon compound and a solvent; the organosilicon compound accounts for 2-6 vol% of the organosilicon compound solution.

[0018] Preferably, the polymerized monomers account for 15-25 vol% of the mixed solution; and / or

[0019] The temperature of the polymerization reaction is 75-85℃, and the time is 1-2 h.

[0020] Preferably, the concentration of the (NH4)2PdCl4 solution is 3-7 mM; and / or

[0021] The time of the ion exchange is 20-40 min.

[0022] Preferably, the chemical plating solution comprises a metal salt, a reducing agent, a pH adjuster, a complexing agent, a buffer and water; the metal salt is at least one of copper salt, nickel salt.

[0023] Preferably, the temperature of the metal layer deposition is 25-95℃; and / or

[0024] The rate of the metal layer deposition is 2.5-5 μm / h.

[0025] The application provides a flexible electric heating material in a second aspect, which is prepared by the preparation method in the first aspect.

[0026] The application provides an application of the flexible electric heating material in the second aspect, which is used for driving an unfolding device.

[0027] Compared with the prior art, the application has at least the following beneficial effects:

[0028] The application firstly uses vacuum plasma treatment to clean the surface of the fiber fabric and generate active groups of hydroxyl on the surface of the fiber fabric, so that the activity of the fiber fabric is enhanced; then the organic silicon compound containing carbon-carbon double bonds is grafted on the surface of the fiber fabric, and polymer brushes are generated on the surface of the fiber fabric through polymerization reaction of the quaternary ammonium salt containing carbon-carbon double bonds under the action of the initiator; then [PdCl4]2- is introduced into the surface of the fiber fabric through ion exchange reaction; finally, [PdCl4]2- is reduced to Pd as a reaction site for subsequent metal layer deposition process in the process of electroless plating, so as to promote the deposition of the metal layer on the surface of the fiber fabric, form a conductive path, and endow the fiber fabric with a heating function, so that the flexible electric heating material with an integrated structure is finally obtained. The flexible electric heating material prepared by the application has high strength, adjustable heating efficiency, and excellent mechanical properties and reliability, and can maintain excellent mechanical properties and heating properties in a complex environment.

[0029] The flexible electric heating material provided by the application can be accurately cut into a heating circuit through die cutting technology, and can be integrally formed with a shape memory material to obtain a shape memory composite material with high strength, good interface bonding and adjustable heating efficiency, so that stable and reliable shape memory composite material driving function can be realized in a complex environment, the strict requirements of the aerospace field on the shape memory composite material driving device can be met, and the problem of overheating and debonding of the traditional surface adhesion type heating film is solved. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0031] Figure 1 is a preparation flowchart of the flexible electric heating material provided by the application;

[0032] Figure 2is an electrical resistance test diagram of the flexible electric heating material before and after being compounded with the shape memory material provided in Embodiment 4 of the present application;

[0033] Figure 3 is an unfolded diagram of the shape memory material composite obtained after the flexible electric heating material provided in Embodiment 4 of the present application is compounded with the shape memory material. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0035] The present application provides, in a first aspect, a preparation method of a flexible electric heating material, the preparation method comprising the following steps:

[0036] S1. performing vacuum plasma treatment on a fiber fabric to obtain an activated fiber fabric;

[0037] S2. grafting an organosilicon compound on the surface of the activated fiber fabric to obtain a first modified fiber fabric; the organosilicon compound is a silane coupling agent containing a carbon-carbon double bond;

[0038] S3. placing the first modified fiber fabric in a mixed solution containing an initiator and a polymerization monomer to perform a polymerization reaction and grow a polymer brush, thereby obtaining a second modified fiber fabric; the polymerization monomer is a quaternary ammonium salt containing a carbon-carbon double bond;

[0039] S4. placing the second modified fiber fabric in a (NH4)2PdCl4 solution to perform ion exchange, thereby obtaining a third modified fiber fabric;

[0040] S5. placing the third modified fiber fabric in a chemical plating solution to deposit a metal layer, thereby obtaining a flexible electric heating material.

[0041] The application firstly adopts vacuum plasma treatment to clean the surface of the fiber fabric and generate active groups of hydroxyl on the surface of the fiber fabric, thereby enhancing the activity of the fiber fabric; then grafts an organic silicon compound containing a carbon-carbon double bond on the surface of the fiber fabric, and under the action of an initiator, carries out a polymerization reaction with a quaternary ammonium salt containing a carbon-carbon double bond to generate a polymer brush on the surface of the fiber fabric; then introduces [PdCl4]2- into the surface of the fiber fabric through an ion exchange reaction; finally, in the process of electroless plating, [PdCl4]2- is first reduced to Pd to provide a reaction site for the subsequent metal layer deposition process, thereby promoting the deposition of the metal layer on the surface of the fiber fabric to form a conductive path, and endowing the fiber fabric with a heating function, so that a flexible electric heating material with an integrated structure is finally obtained. The flexible electric heating material prepared by the application has high strength and adjustable heating efficiency, the fiber fabric and the metal layer (heating layer) are tightly combined, has excellent mechanical properties and reliability, and can maintain excellent mechanical properties and heating properties in a complex environment.

[0042] According to some preferred embodiments, the fibers in the fiber fabric are one or more of carbon fibers, glass fibers, Kevlar fibers, and polyester fibers.

[0043] According to some preferred embodiments, the silane coupling agent containing a carbon-carbon double bond is 3-(trimethoxysilyl)propyl methacrylate.

[0044] According to some preferred embodiments, the quaternary ammonium salt containing a carbon-carbon double bond is methacryloyloxyethyl trimethyl ammonium chloride.

[0045] It should be noted that the application takes 3-(trimethoxysilyl)propyl methacrylate and methacryloyloxyethyl trimethyl ammonium chloride as examples for the purpose of describing the technical solutions of the application, but not for limitation, and other silane coupling agents containing a carbon-carbon double bond and quaternary ammonium salts containing a carbon-carbon double bond are also applicable to the technical solutions of the application.

[0046] According to some preferred embodiments, the initiator is one or more of a peroxide initiator and an azo initiator; the peroxide initiator is preferably one or more of potassium persulfate, ammonium persulfate, and hydrogen peroxide; and the azo initiator is preferably azobisisobutyronitrile.

[0047] According to some preferred embodiments, the time of the vacuum plasma treatment is not less than 30 min.

[0048] According to some preferred embodiments, grafting the organic silicon compound on the activated surface of the fiber fabric comprises:

[0049] reacting the activated fiber fabric in a solution of a silicone compound for 1-2 hours, wherein the solution of the silicone compound is obtained by mixing the silicone compound and a solvent, and the silicone compound accounts for 2-6 vol% of the solution of the silicone compound;

[0050] According to some preferred embodiments, the solvent is obtained by mixing 95 vol% of ethanol, 1 vol% of acetic acid and 4 vol% of water.

[0051] According to some preferred embodiments, the polymerized monomers account for 15-25 vol% of the mixed solution; and / or

[0052] The polymerization reaction is performed at a temperature of 75-85°C for 1-2 hours.

[0053] According to some preferred embodiments, the (NH4)2PdCl4 solution has a concentration of 3-7 mM; and / or

[0054] The ion exchange is performed for 20-40 minutes.

[0055] According to some preferred embodiments, the electroless plating solution comprises a metal salt, a reducing agent, a pH adjuster, a complexing agent, a buffer and water, and the metal salt is at least one of a copper salt and a nickel salt.

[0056] In some more preferred embodiments of the present application, the third modified fiber fabric is placed in an electroless plating solution to deposit a metal layer, which comprises: first placing the third modified fiber fabric in a copper electroless plating solution to deposit a copper plating layer; and then placing the third modified fiber fabric with the deposited copper plating layer in a nickel electroless plating solution to deposit a nickel plating layer. The copper layer has good electrical conductivity, and the nickel layer has good thermal conductivity, so that the prepared electric heating material has both excellent electrical conductivity and thermal conductivity, and the nickel layer can effectively prevent the copper layer from being oxidized during heating.

[0057] According to some preferred embodiments, when the copper plating layer is deposited, the copper electroless plating solution used comprises a copper salt, a reducing agent, a complexing agent, a buffer and a pH adjuster, and the copper layer is deposited at a temperature of 25-30°C.

[0058] The copper salt is one or more of CuSO4·5H2O, CuCl2·2H2O and Cu(NO3)2·3H2O, and preferably CuSO4·5H2O, and has a concentration of 10-15 g / L; and is used to provide Cu 2+ to deposit a metal copper layer.

[0059] The reducing agent is HCHO (formaldehyde), NaBH4 (sodium borohydride) or NaH2PO2 (sodium hypophosphite), and preferably HCHO, and has a concentration of 3-5 mL / L; and is used to reduce copper ions to metal copper.

[0060] The complexing agent is EDTA-2Na (ethylenediaminetetraacetic acid disodium), sodium citrate or amino acetic acid (glycine), preferably EDTA-2Na, with a concentration of 30-40 g / L; used to stabilize the copper ions and prevent uneven deposition.

[0061] The buffering agent is Na2CO3 (sodium carbonate), with a concentration of 3-5 g / L; used to adjust the stability of the solution and control the reaction rate.

[0062] The pH regulator is NaOH (sodium hydroxide), KOH (potassium hydroxide) or NH4OH (ammonia), preferably NaOH, with a concentration of 10-15 g / L; used to adjust the pH of the solution to 12-13 to ensure that the deposition reaction is carried out under alkaline conditions.

[0063] According to some preferred embodiments, when depositing a nickel plating layer, the nickel electroless plating solution used includes a nickel salt, a reducing agent, a complexing agent, a buffering agent and a pH regulator; the deposition temperature of the nickel layer is 85-95°C

[0064] The nickel salt is one or more of NiSO4·6H2O (nickel sulfate hexahydrate), NiCl2·6H2O (nickel chloride hexahydrate) and Ni(NO3)2·6H2O (nickel nitrate hexahydrate), preferably NiSO4·6H2O, with a concentration of 20-30 g / L; used to provide Ni 2+ to deposit a metal nickel layer.

[0065] The reducing agent is one or more of NaH2PO2·H2O (sodium hypophosphite), NaBH4 (sodium borohydride) and H2PO3 - -(dihydrogen phosphate), preferably NaH2PO2·H2O, with a concentration of 10-20 g / L; used to reduce nickel ions to metal nickel.

[0066] The complexing agent is one or more of C4H6O6 (tartaric acid), citric acid and EDTA, preferably C4H6O6, with a concentration of 5-10 g / L; used to stabilize nickel ions and prevent uneven deposition.

[0067] The buffering agent is one or more of CH3COONa (sodium acetate), sodium citrate and K2CO3 (potassium carbonate), preferably CH3COONa, with a concentration of 15-20 g / L; used to adjust the acid-base balance of the solution and ensure uniform plating.

[0068] The pH regulator is ammonia; used to adjust the pH to 4.5-5.0 to ensure that the deposition reaction is carried out under suitable acidic conditions.

[0069] According to some preferred embodiments, the temperature at which the metal layer is deposited is 25-95°C; and / or

[0070] The rate of deposition of the metal layer is 2.5-5 μm / h.

[0071] The present application provides, in a second aspect, a flexible electric heating material prepared by the method of the first aspect.

[0072] The present application provides, in a third aspect, an application of the flexible electric heating material of the second aspect, which is compounded with a shape memory polymer to obtain a shape memory composite material, and is used to drive an unfolding device.

[0073] The flexible electric heating material provided by the present application can be accurately cut into a heating circuit by a die cutting technology, and can be integrally formed with a shape memory material to obtain a shape memory composite material with high strength, good interface bonding and adjustable heating efficiency, and can realize stable and reliable shape memory composite material driving function in a complex environment, and can meet the stringent requirements of the aerospace field on the shape memory composite material driving device, and solve the problem of overheating and debonding of the traditional surface adhesion type heating film.

[0074] The preparation of the shape memory composite material comprises: (1) forming a heating circuit on the flexible electric heating material by a die cutting process; and (2) compounding the die cut flexible electric heating material with a shape memory material to obtain a shape memory composite material. The die cut flexible electric heating material is compounded with the shape memory material by an integrated forming mode, so that the flexible electric heating material and the shape memory material have good mechanical synergy, and high strength and reliability are ensured during use. It should be noted that the flexible electric heating material and the shape memory material of the present application can be integrally formed by using the process of preparing a composite material from conventional fiber fabric and resin, for example, vacuum assisted forming.

[0075] The obtained integrated shape memory composite material is applied to a driving unfolding device, when the flexible electric heating material is powered and heated, the shape memory composite material and structure are deformed by heating, and the driving device can be unfolded. This integrated design solves the problems of poor adhesion, overheating and debonding of the traditional heating film, and improves the reliability and stability of the device.

[0076] In order to more clearly illustrate the technical solutions and advantages of the present application, the present application will be further described below in conjunction with examples. The source of each reagent used in the examples and comparative examples of the present application is not specifically limited, and can be directly purchased or synthesized by oneself.

[0077] Example 1

[0078] S1. Put the carbon fiber fabric into a vacuum plasma chamber and treat for 30 minutes to obtain an activated carbon fiber fabric;

[0079] S2. The activated carbon fiber fabric is reacted in a room temperature organic silicon compound solution for 1 hour to obtain a first modified carbon fiber fabric; wherein the organic silicon compound solution is obtained by dissolving 3-(trimethoxysilyl) propyl methacrylate in a solvent, wherein the 3-(trimethoxysilyl) propyl methacrylate accounts for 4 vol% of the organic silicon compound solution, and the solvent is obtained by mixing 95 vol% of ethanol, 1 vol% of acetic acid and 4 vol% of deionized water;

[0080] S3. The first modified carbon fiber fabric is washed with deionized water and then immersed in a solution containing potassium persulfate and methacryloyloxyethyl trimethyl ammonium chloride (20 vol%) and polymerized at 80℃ for 1 hour to obtain a second modified carbon fiber fabric;

[0081] S4. The second modified carbon fiber fabric is immersed in a (NH4)2PdCl4 solution with a concentration of 5 mM for 30 minutes to perform an ion exchange reaction to obtain a third modified carbon fiber fabric.

[0082] S5. The third modified carbon fiber fabric is placed in a chemical deposition tank containing a copper electroless plating solution to deposit a copper layer at 25℃ for 1 hour; and then the material after the copper layer is deposited is placed in a chemical deposition tank containing a nickel electroless plating solution to deposit a nickel layer at 85℃ for 2.3 hours to obtain a flexible electric heating material; wherein the concentration of CuSO4·5H2O in the copper electroless plating solution is 10 g / L, the concentration of HCHO is 3 mL / L, the concentration of EDTA-2Na is 30 g / L, the concentration of Na2CO3 (sodium carbonate) is 3 g / L, and the pH is adjusted to 12 by using a NaOH solution; the concentration of NiSO4·6H2O in the nickel electroless plating solution is 20 g / L, the concentration of NaH2PO2·H2O is 10 g / L, the concentration of CH3COONa is 15 g / L, the concentration of C4H6O6 (tartaric acid) is 5 g / L, and the pH is adjusted to 4.5 by using ammonia.

[0083] Embodiments 2-5 of the present application are basically the same as Embodiment 1, and the differences are shown in Table 1.

[0084] Table 1. Comparison of parameters in the preparation process of Embodiments 1-5 of the present application

[0085]

[0086] As can be seen from Table 1, the thickness of the plating layer is controlled by adjusting the electroplating time, the resistivity of the flexible electric heating material is controlled, and the heating effect is controlled to meet different use requirements.

[0087] The flexible electric heating material prepared in Embodiment 4 is compounded with a shape memory material by a vacuum assisted forming method to obtain a shape memory composite material. Figure 2It can be seen that the resistance of the flexible electric heating material before compounding and the shape memory composite material after compounding is unchanged, which shows that the resistance of the flexible electric heating material is stable, and the introduction of the shape memory material does not affect the resistance of the flexible electric heating material. Figure 3 It can be seen that when the flexible electric heating material is powered and heated, the shape memory composite material can be completely unfolded in 14s, which can meet the use requirements of the shape memory composite material driving device in the field of aerospace.

[0088] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. Use of a flexible electrically heatable material, characterized in that The flexible electric heating material is integrally formed with a shape memory polymer to obtain a shape memory composite material for driving an unfolding device. The preparation method of the flexible electric heating material comprises the following steps: S1. The fiber fabric is subjected to vacuum plasma treatment to obtain an activated fiber fabric; the fibers in the fiber fabric are one or more of carbon fibers, Kevlar fibers, and polyester fibers; S2. An organic silicon compound is grafted on the surface of the activated fiber fabric to obtain a first modified fiber fabric; the organic silicon compound is a silane coupling agent containing a carbon-carbon double bond; S3. The first modified fiber fabric is placed in a mixed solution containing an initiator and a polymerization monomer to perform a polymerization reaction and grow a polymer brush to obtain a second modified fiber fabric; The polymerization monomer is a quaternary ammonium salt containing a carbon-carbon double bond; S4. The second modified fiber fabric is placed in a (NH4)2PdCl4 solution to perform ion exchange to obtain a third modified fiber fabric; S5. The third modified fiber fabric is placed in a chemical plating solution containing a copper salt to perform metal layer deposition; and then it is placed in a chemical plating solution containing a nickel salt to perform metal layer deposition to obtain a flexible electric heating material; the chemical plating solution contains a metal salt, a reducing agent, a pH adjuster, a complexing agent, a buffer, and water; the metal salt is a copper salt and a nickel salt; the temperature of the metal layer deposition is 25-95°C; and the rate of the metal layer deposition is 2.5-5 µm / h.

2. The use according to claim 1, wherein The silane coupling agent containing a carbon-carbon double bond is 3-(trimethoxysilyl)propyl methacrylate; The quaternary ammonium salt containing a carbon-carbon double bond is methacryloyloxyethyltrimethylammonium chloride.

3. The use according to claim 1, wherein The initiator is one or more of a peroxide initiator and an azo initiator.

4. Use according to claim 1, characterized in that, The time of the vacuum plasma treatment is not less than 30 min.

5. The use according to claim 1, characterized in that, Grafting the organic silicon compound on the surface of the activated fiber fabric comprises: The activated fiber fabric is placed in an organic silicon compound solution and reacts for 1-2 h; the organic silicon compound solution is obtained by mixing an organic silicon compound and a solvent; and the organic silicon compound accounts for 2-6 vol% of the organic silicon compound solution.

6. The use according to claim 1, characterized in that, The polymerization monomer accounts for 15-25 vol% of the mixed solution.

7. The use according to claim 1, wherein The temperature of the polymerization reaction is 75-85°C, and the time is 1-2 h.

8. The use according to claim 1, characterized in that, The concentration of the (NH4)2PdCl4 solution is 3-7 mM.

9. The use according to claim 1, characterized in that, The time of the ion exchange is 20-40 min.

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