A CNT conductive heating film, a preparation method and application thereof

Abstract

The present application relates to a kind of CNT conductive heating film and its preparation method and application, belong to conductive heating film technical field.The present application is creatively first using ethylenediamine to the surface modification of amino of graphitized carbon nanotube that is pretreated with hydrochloric acid, to obtain component A, then with 1,2,7,8-diepoxyoctane as crosslinking agent, based on the bonding of epoxy group and amino, crosslinking carboxymethyl chitosan containing amino is coated to the surface of component A, form first coating, then add aniline as modifier, based on in-situ polymerization, build second coating, then obtain modified graphitized carbon nanotube, make it with organic resin polymer and other raw materials according to conventional preparation method can be prepared a kind of CNT conductive heating film, well solve the agglomeration of graphitized carbon nanotube, dispersibility problem, heating performance is excellent, very suitable for application in warm product.

Description

Technical Field

[0001] The present invention belongs to the technical field of conductive heating films, and specifically relates to a CNT conductive heating film and a preparation method and application thereof. Background Art

[0002] Conductive heating film is a type of thin film material that can generate heat when electricity is applied. It is widely used in various fields due to its many advantages such as high heating efficiency and good safety. Among them, the heating performance of the conductive heating film depends to a large extent on the inorganic filler added to it, and carbon nanotubes, namely CNTs, are a one-dimensional quantum material with a special structure. Due to its excellent electrical properties, the inorganic fillers added to the conductive heating film are often mainly carbon nanotubes. However, these conductive heating films with added carbon nanotubes still have certain disadvantages that limit their actual application effects. This is because the heating performance of ordinary carbon nanotubes still has a lot of room for improvement. Although many existing technologies will choose graphitized carbon nanotubes to replace ordinary carbon nanotubes to obtain better heating performance, graphitized carbon nanotubes are essentially inorganic particles, the agglomeration phenomenon is very obvious, and the dispersion is not good, and ultimately it is difficult to play the desired effect. Summary of the Invention

[0003] In response to the problems existing in the prior art, the purpose of the present invention is to provide a CNT conductive heating film and its preparation method and application. The present invention creatively uses ethylenediamine to first perform amino surface modification on the graphitized carbon nanotubes pretreated with hydrochloric acid to obtain component A, and then uses 1,2,7,8-diepoxyoctane as a cross-linking agent. Based on the bonding effect between the epoxy group and the amino group, the amino-containing carboxymethyl chitosan is cross-linked and coated on the surface of component A to form a first coating layer. Then, aniline is added as a modifier, and a second coating layer is constructed based on in situ polymerization to obtain modified graphitized carbon nanotubes. A CNT conductive heating film can be prepared by combining it with raw materials such as organic resin polymers according to conventional preparation methods, which effectively solves the problems of agglomeration and dispersion of graphitized carbon nanotubes, has excellent heating performance, and is very suitable for application in thermal insulation products.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for preparing a CNT conductive heating film, the method comprising the following steps:

[0006] (1) melt-mixing a first thermoplastic polyurethane elastomer and modified graphitized carbon nanotubes in a mass ratio of 80-85:15-20, coating, and naturally cooling to room temperature to obtain a film layer;

[0007] (2) mixing the second thermoplastic polyurethane elastomer, the insulating agent and N,N-dimethylformamide in a mass ratio of 10:0.2-0.3:80-100 at 60-80℃ under ultrasonic stirring for 6-12h to obtain a film solution;

[0008] (3) coating the film solution on one side of the film layer and drying to complete the preparation.

[0009] As a preferred technical solution of the present application, the modified graphitized carbon nanotube in step (1) is prepared by the following steps:

[0010] Step A: adding 1-1.2 parts by weight of pretreated graphitized carbon nanotube and 8-10 parts by weight of ethylenediamine to 40-50 parts by weight of N,N-dimethylformamide, then mixing at 55-60℃ under ultrasonic stirring for 40-48h, filtering, washing with deionized water, and finally vacuum drying at 40-80℃ until constant weight to obtain component A;

[0011] Step B: adding 1-1.5 parts by weight of component A to 50-70 parts by weight of deionized water, then mixing at room temperature under ultrasonic stirring for 15-30min to obtain component B;

[0012] Step C: adding 0.5-1 parts by weight of carboxymethyl chitosan to 35-40 parts by weight of deionized water, then mixing at 30-40℃ under ultrasonic stirring for 10-15min to obtain component C;

[0013] Step D: adding component C and 0.2-0.3 parts by weight of 1,2,7,8-diepoxyoctane to component B under stirring at 70-80℃, continuing to stir at constant temperature for 6-8h after complete addition, filtering, washing with deionized water, and finally vacuum drying at 40-80℃ until constant weight to obtain component D;

[0014] Step E: adjusting the pH of 60-80 parts by weight of ethanol aqueous solution to 3-3.5 with hydrochloric acid aqueous solution, then adding component D and 0.2-0.3 parts by weight of aniline, followed by adding 8-10 parts by weight of 10% ammonium persulfate aqueous solution under ultrasonic stirring at ice bath, continuing to stir at constant temperature for 4-6h after complete addition, standing for 4-6h, filtering, washing with deionized water, and finally vacuum drying at 40-80℃ until constant weight to complete the preparation.

[0015] Further, the pretreated graphitized carbon nanotube in step A is prepared by the following steps:

[0016] Add 0.8-1 parts by weight of graphitized carbon nanotubes to 60-80 parts by weight of 37% hydrochloric acid aqueous solution, then mix under ultrasonic stirring at room temperature for 1-2 hours at a power of 300-500 W, filter, wash the residue with deionized water, and finally dry under vacuum at 40-80°C until constant weight, to complete the preparation.

[0017] Further, the power of the ultrasonic stirring in step A is 300-500 W.

[0018] Further, the power of the ultrasonic stirring in step B is 300-500 W.

[0019] Further, the power of the ultrasonic stirring in step C is 300-500 W.

[0020] Further, the dropping rate of component C in step D is controlled at 2-3 seconds per drop.

[0021] Further, the dropping rate of 1,2,7,8-diepoxyoctane in step D is controlled at 5 seconds per drop.

[0022] Further, the mass fraction of the hydrochloric acid aqueous solution in step E is 37%.

[0023] Further, the mass fraction of the ethanol aqueous solution in step E is 80-90%.

[0024] Further, the power of the ultrasonic stirring in step E is 300-500 W.

[0025] Further, the dropping rate in step E is controlled at 3-5 seconds per drop.

[0026] As a preferred technical solution of the present application, the melt mixing in step (1) refers to mixing under stirring at 190-200°C for 10-15 minutes.

[0027] As a preferred technical solution of the present application, the insulating agent in step (2) is nanosilica.

[0028] As a preferred technical solution of the present application, the power of the ultrasonic stirring in step (2) is 300-500 W.

[0029] As a preferred technical solution of the present application, the drying in step (3) refers to drying under vacuum at 85-90°C for 1 hour.

[0030] A CNT conductive heating film prepared by the preparation method.

[0031] Application of a CNT conductive heating film, which is applied to a warm-keeping product.

[0032] The present application has the following advantages:

[0033] (1) The present invention creatively uses ethylenediamine to modify the surface of graphitized carbon nanotubes that have been pretreated with hydrochloric acid with amino groups, thereby obtaining component A. Then, 1,2,7,8-diepoxyoctane is used as a cross-linking agent, and based on the bonding effect between the epoxy group and the amino group, the amino-containing carboxymethyl chitosan is cross-linked and coated on the surface of component A to form a first coating layer. Then, aniline is added as a modifier, and based on in situ polymerization, a second coating layer is constructed to obtain modified graphitized carbon nanotubes. A CNT conductive heating film can be prepared by combining it with raw materials such as organic resin polymers according to conventional preparation methods, which effectively solves the problems of agglomeration and dispersion of graphitized carbon nanotubes, has excellent heating performance, and is very suitable for application in thermal insulation products.

[0034] (2) The present invention creatively coats graphitized carbon nanotubes with organic polymers twice, namely, surface crosslinking of carboxymethyl chitosan and in-situ polymerization of aniline, thereby forming a three-layer composite structure of graphitized carbon nanotubes / carboxymethyl chitosan / polyaniline, and obtaining a modified graphitized carbon nanotube, which gives the obtained CNT conductive heating film excellent heating performance and effectively solves the problems of agglomeration and dispersion of graphitized carbon nanotubes in the organic resin polymer matrix. On the one hand, the crosslinking of carboxymethyl chitosan affects the electron cloud distribution on the surface of the graphitized carbon nanotubes, thereby enhancing the carbon element activity of the graphitized carbon nanotubes, increasing the resistance, and obtaining a better heating effect. On the other hand, aniline is converted into polyaniline after in-situ polymerization, which has strong conductive properties and can promote the establishment of a good conductive network between each modified graphitized carbon nanotube, thereby improving the overall heating efficiency. At the same time, after coating the graphitized carbon nanotubes as an organic polymer, it can improve the interface compatibility, reduce the occurrence of agglomeration, and promote the uniform dispersion of the modified graphitized carbon nanotubes.

[0035] (3) The present invention creatively coats graphitized carbon nanotubes twice to prepare a modified graphitized carbon nanotube. During the coating process, although carboxymethyl chitosan is also an organic polymer and can play a role in improving interfacial compatibility, it cannot achieve a good technical effect when used as the "outermost layer". The possible reason is that it will hinder the continuity of the conductive path and it is difficult to achieve efficient heat generation. Only when used as the "middle layer" can the three play an excellent synergistic effect. DETAILED DESCRIPTION

[0036] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0037] The graphitized carbon nanotubes in all the examples and comparative examples of the present application are purchased from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd., and the number is XFM46; the carboxymethyl chitosan is purchased from Jinan Xinzhiyuan Biological Technology Co., Ltd.; the first thermoplastic polyurethane elastomer is purchased from Bayer (Germany), and the model is 95A; the second thermoplastic polyurethane elastomer is purchased from Wanhua Chemical Group Co., Ltd., and the model is WHT-1185EC; the nano-silicon dioxide is purchased from Shanghai Xiangtian Nanometer Material Co., Ltd., and the model is XT-SiO2-02; the thickness of the CNT conductive heating film is 100 μm; and the thickness of the film layer is 70 μm.

[0038] Example 1

[0039] A preparation method of a CNT conductive heating film, the preparation method comprising the following steps:

[0040] (1) melt-mixing the first thermoplastic polyurethane elastomer and the modified graphitized carbon nanotubes at a mass ratio of 80:15, coating, and naturally cooling to room temperature to obtain a film layer;

[0041] (2) mixing the second thermoplastic polyurethane elastomer, the insulating agent and N,N-dimethylformamide at a mass ratio of 10:0.2:80 in an ultrasonic bath at 60°C for 6h to obtain a film solution;

[0042] (3) coating the film solution on one side of the film layer, and drying to complete the preparation.

[0043] The modified graphitized carbon nanotubes in step (1) are prepared by the following steps:

[0044] Step A: adding 1 part by weight of pretreated graphitized carbon nanotubes and 8 parts by weight of ethylenediamine into 40 parts by weight of N,N-dimethylformamide, and then mixing in an ultrasonic bath at 55°C for 40h, suction filtering, washing the filter residue with deionized water, and finally vacuum drying at 40°C until constant weight to obtain component A;

[0045] Step B: adding 1 part by weight of component A into 50 parts by weight of deionized water, and then mixing in an ultrasonic bath at room temperature for 15min to obtain component B;

[0046] Step C: adding 0.5 parts by weight of carboxymethyl chitosan into 35 parts by weight of deionized water, and then mixing in an ultrasonic bath at 30°C for 10min to obtain component C;

[0047] Step D: adding component C and 0.2 parts by weight of 1,2,7,8-diepoxyoctane into component B dropwise while stirring at 70°C, continuing to stir at constant temperature for 6h after the dropwise addition is completed, suction filtering, washing the filter residue with deionized water, and finally vacuum drying at 40°C until constant weight to obtain component D;

[0048] Step E: 60 parts by weight of ethanol aqueous solution is adjusted to pH 3 with hydrochloric acid aqueous solution, then the component D and 0.2 parts by weight of aniline are added, followed by dropwise addition of 8 parts by weight of 10% ammonium persulfate aqueous solution under ice bath and ultrasonic stirring, and after the dropwise addition is completed, constant temperature stirring is continued for 4 h, and then the mixture is left to stand for 4 h, filtered, washed with deionized water, and finally dried under vacuum at 40°C until the weight is constant.

[0049] The pretreated graphitized carbon nanotubes in Step A are prepared by the following steps:

[0050] 0.8 parts by weight of graphitized carbon nanotubes are added to 60 parts by weight of 37% hydrochloric acid aqueous solution, and then mixed by stirring under ultrasonic waves at room temperature and a power of 300 W for 1 h, filtered, washed with deionized water, and finally dried under vacuum at 40°C until the weight is constant.

[0051] The power of the ultrasonic waves in Step A is 300 W.

[0052] The power of the ultrasonic waves in Step B is 300 W.

[0053] The power of the ultrasonic waves in Step C is 300 W.

[0054] The dropwise addition rate of the component C in Step D is controlled at 2 s / drop.

[0055] The dropwise addition rate of 1,2,7,8-diepoxyoctane in Step D is controlled at 5 s / drop.

[0056] The mass fraction of the hydrochloric acid aqueous solution in Step E is 37%.

[0057] The mass fraction of the ethanol aqueous solution in Step E is 80%.

[0058] The power of the ultrasonic waves in Step E is 300 W.

[0059] The dropwise addition rate in Step E is controlled at 3 s / drop.

[0060] The melt mixing in Step (1) refers to mixing by stirring at 190°C for 10 min.

[0061] The insulating agent in Step (2) is nanosilica.

[0062] The power of the ultrasonic waves in Step (2) is 300 W.

[0063] The drying in Step (3) refers to drying under vacuum at 85°C for 1 h.

[0064] A CNT conductive heating film prepared by the preparation method described above.

[0065] Use of a CNT conductive heating film in a thermal product.

[0066] Example 2

[0067] A preparation method of a CNT conductive heating film, comprising the following steps:

[0068] (1) melt-mixing a first thermoplastic polyurethane elastomer and modified graphitized carbon nanotubes at a mass ratio of 85:20, coating, and naturally cooling to room temperature to obtain a film layer;

[0069] (2) mixing a second thermoplastic polyurethane elastomer, an insulating agent, and N,N-dimethylformamide at a mass ratio of 10:0.3:100 at 80°C in an ultrasonic stirrer for 12h to obtain a film solution;

[0070] (3) coating the film solution on one side of the film layer and drying to complete the preparation.

[0071] The modified graphitized carbon nanotubes in step (1) are prepared by the following steps:

[0072] Step A: adding 1.2 parts by weight of pretreated graphitized carbon nanotubes and 10 parts by weight of ethylenediamine to 50 parts by weight of N,N-dimethylformamide, then mixing at 60°C in an ultrasonic stirrer for 48h, filtering, washing the filter residue with deionized water, and finally drying at 80°C under vacuum until the weight is constant to obtain component A;

[0073] Step B: adding 1.5 parts by weight of component A to 70 parts by weight of deionized water, then mixing at room temperature in an ultrasonic stirrer for 30min to obtain component B;

[0074] Step C: adding 1 part by weight of carboxymethyl chitosan to 40 parts by weight of deionized water, then mixing at 40°C in an ultrasonic stirrer for 15min to obtain component C;

[0075] Step D: adding component C and 0.3 parts by weight of 1,2,7,8-diepoxyoctane to component B at 80°C while stirring, continuing to stir at constant temperature for 8h after the addition is completed, filtering, washing the filter residue with deionized water, and finally drying at 80°C under vacuum until the weight is constant to obtain component D;

[0076] Step E: 80 parts by weight of an ethanol aqueous solution is adjusted to a pH of 3.5 using an aqueous hydrochloric acid solution, then the component D and 0.3 parts by weight of aniline are added, then 10 parts by weight of a 10% mass fraction ammonium persulfate aqueous solution is added dropwise in an ice bath under ultrasonic stirring, after the dropwise addition is completed, constant temperature stirring is continued for 6 hours of mixing, standing for 6 hours, suction filtration, taking the filter residue, washing with deionized water, and finally vacuum drying at 80°C until a constant weight is obtained.

[0077] The pretreated graphitized carbon nanotubes of Step A are prepared by the following steps:

[0078] 1 part by weight of graphitized carbon nanotubes is added to 80 parts by weight of a 37% mass fraction aqueous hydrochloric acid solution, then mixed under stirring at room temperature for 2 hours under ultrasonic stirring at a power of 500W, suction filtration, taking the filter residue, washing with deionized water, and finally vacuum drying at 80°C until a constant weight is obtained.

[0079] The power of the ultrasonic stirring of Step A is 500W.

[0080] The power of the ultrasonic stirring of Step B is 500W.

[0081] The power of the ultrasonic stirring of Step C is 500W.

[0082] The dropwise addition rate of the component C of Step D is controlled at 3s / drop.

[0083] The dropwise addition rate of the 1,2,7,8-diepoxyoctane of Step D is controlled at 5s / drop.

[0084] The mass fraction of the aqueous hydrochloric acid solution of Step E is 37%.

[0085] The mass fraction of the ethanol aqueous solution of Step E is 90%.

[0086] The power of the ultrasonic stirring of Step E is 500W.

[0087] The dropwise addition rate of Step E is controlled at 5s / drop.

[0088] The melt mixing of Step (1) refers to mixing under stirring at 200°C for 15min.

[0089] The insulating agent of Step (2) is nanosilica.

[0090] The power of the ultrasonic stirring of Step (2) is 500W.

[0091] The drying of Step (3) refers to vacuum drying at 90°C for 1h.

[0092] A CNT conductive heating film prepared by the preparation method described above.

[0093] Use of a CNT conductive heating film in a thermal product.

[0094] Example 3

[0095] A preparation method of a CNT conductive heating film, comprising the following steps:

[0096] (1) melt-mixing a first thermoplastic polyurethane elastomer and modified graphitized carbon nanotubes at a mass ratio of 83:18, coating, and naturally cooling to room temperature to obtain a film layer;

[0097] (2) mixing a second thermoplastic polyurethane elastomer, an insulating agent, and N,N-dimethylformamide at a mass ratio of 10:0.25:90 at 70°C in an ultrasonic bath for 8h to obtain a film solution;

[0098] (3) coating the film solution on one side of the film layer and drying to complete the preparation.

[0099] The modified graphitized carbon nanotubes in step (1) are prepared by the following steps:

[0100] Step A: adding 1.1 parts by weight of pretreated graphitized carbon nanotubes and 9 parts by weight of ethylenediamine to 45 parts by weight of N,N-dimethylformamide, then mixing at 58°C in an ultrasonic bath for 45h, filtering, washing the filter residue with deionized water, and finally drying at 60°C under vacuum until the weight is constant to obtain component A;

[0101] Step B: adding 1.3 parts by weight of component A to 60 parts by weight of deionized water, then mixing at room temperature in an ultrasonic bath for 20min to obtain component B;

[0102] Step C: adding 0.8 parts by weight of carboxymethyl chitosan to 38 parts by weight of deionized water, then mixing at 35°C in an ultrasonic bath for 13min to obtain component C;

[0103] Step D: adding component C and 0.25 parts by weight of 1,2,7,8-diepoxyoctane to component B while stirring at 75°C, continuing to stir at constant temperature for 7h after the addition is completed, filtering, washing the filter residue with deionized water, and finally drying at 60°C under vacuum until the weight is constant to obtain component D;

[0104] Step E: 70 parts by weight of an ethanol aqueous solution is adjusted to a pH of 3.3 using an aqueous hydrochloric acid solution, then the component D and 0.25 parts by weight of aniline are added, then 9 parts by weight of a 10% mass fraction ammonium persulfate aqueous solution is added dropwise in an ice bath under ultrasonic stirring, after the dropwise addition is completed, constant temperature stirring is continued for 5 h, the mixture is allowed to stand for 5 h, then the residue is filtered, washed with deionized water, and finally dried under vacuum at 60°C until the weight is constant.

[0105] The pretreated graphitized carbon nanotubes of Step A are prepared by the following steps:

[0106] 0.9 parts by weight of graphitized carbon nanotubes are added to 70 parts by weight of a 37% mass fraction aqueous hydrochloric acid solution, then the mixture is stirred under ultrasonic stirring at room temperature at a power of 400W for 1.5 h, then the residue is filtered, washed with deionized water, and finally dried under vacuum at 70°C until the weight is constant.

[0107] The power of the ultrasonic stirring of Step A is 400W.

[0108] The power of the ultrasonic stirring of Step B is 400W.

[0109] The power of the ultrasonic stirring of Step C is 400W.

[0110] The dropwise addition rate of the component C of Step D is controlled at 2.5 s / drop.

[0111] The dropwise addition rate of the 1,2,7,8-diepoxyoctane of Step D is controlled at 5 s / drop.

[0112] The mass fraction of the aqueous hydrochloric acid solution of Step E is 37%.

[0113] The mass fraction of the ethanol aqueous solution of Step E is 85%.

[0114] The power of the ultrasonic stirring of Step E is 400W.

[0115] The dropwise addition rate of Step E is controlled at 4 s / drop.

[0116] The melt mixing of Step (1) refers to mixing under stirring at 195°C for 13 min.

[0117] The insulating agent of Step (2) is nanosilica.

[0118] The power of the ultrasonic stirring of Step (2) is 400W.

[0119] The drying of Step (3) refers to drying under vacuum at 88°C for 1 h.

[0120] A CNT conductive heating film prepared by the preparation method described above.

[0121] Use of a CNT conductive heating film in a thermal product.

[0122] Comparative Example 1

[0123] On the basis of Example 3, step E is not performed, and the rest remains unchanged.

[0124] Comparative Example 2

[0125] On the basis of Example 3, steps B, C, D and E are not performed, and the rest remains unchanged.

[0126] Comparative Example 3

[0127] On the basis of Example 3, step B is not performed, step D is changed to adjusting the pH of 70 parts by weight of an ethanol aqueous solution (mass fraction 85%) to 3.3 using an aqueous hydrochloric acid solution (mass fraction 37%), then adding 1.3 parts by weight of component A and 0.25 parts by weight of aniline, then adding 9 parts by weight of a 10% ammonium persulfate aqueous solution under ultrasonic treatment (power 400 W) in an ice bath while stirring (the rate of dropwise addition is controlled at 4 s / drop), continuing to stir at constant temperature for 5 h after all the dropwise addition is completed, standing for 5 h, suction filtration, taking the filter residue, washing with deionized water, and finally vacuum drying at 60°C until the weight is constant to obtain component D; step E is changed to adding component D to 60 parts by weight of deionized water, then stirring for 20 min at room temperature under ultrasonic treatment (power 400 W) to obtain component E, then adding component C and 0.25 parts by weight of 1,2,7,8-diepoxyoctane to component E while stirring at 75°C (the rate of dropwise addition of component C is controlled at 2.5 s / drop, and the rate of dropwise addition of 1,2,7,8-diepoxyoctane is controlled at 5 s / drop), continuing to stir at constant temperature for 7 h after all the dropwise addition is completed, suction filtration, taking the filter residue, washing with deionized water, and finally vacuum drying at 60°C until the weight is constant, i.e., the preparation is completed; and the rest remains unchanged.

[0128] Comparative Example 4

[0129] On the basis of Example 3, steps C, D and E are not performed, and step B is changed to adjusting the pH of 70 parts by weight of an ethanol aqueous solution (mass fraction 85%) to 3.3 using an aqueous hydrochloric acid solution (mass fraction 37%), then adding 1.3 parts by weight of component A and 0.25 parts by weight of aniline, then adding 9 parts by weight of a 10% ammonium persulfate aqueous solution under ultrasonic treatment (power 400 W) in an ice bath while stirring (the rate of dropwise addition is controlled at 4 s / drop), continuing to stir at constant temperature for 5 h after all the dropwise addition is completed, standing for 5 h, suction filtration, taking the filter residue, washing with deionized water, and finally vacuum drying at 60°C until the weight is constant, i.e., the preparation is completed; and the rest remains unchanged.

[0130] Test Example 1

[0131] Heat generation performance test:

[0132] The CNT conductive heating film prepared in Example 3 and Comparative Examples 1-4 was respectively pasted with a conductive copper tape, and then each was powered for 80s at 36V (at room temperature) to record the temperature after power-on (rounded to the nearest integer).

[0133] Table 1. Heat generation performance test results

[0134] Temperature / °C Example 3 66 Comparative Example 1 52 Comparative Example 2 48 Comparative Example 3 57 Comparative Example 4 59

[0135] Comparing Example 3 and Comparative Examples 1-4, it can be seen that:

[0136] The difference between Comparative Example 1 and Example 3 is that the modified graphitized carbon nanotube is a graphitized carbon nanotube / carboxymethyl chitosan composite structure.

[0137] The difference between Comparative Example 2 and Example 3 is that the modified graphitized carbon nanotube does not form a composite structure.

[0138] The difference between Comparative Example 3 and Example 3 is that the modified graphitized carbon nanotube is a graphitized carbon nanotube / polystyrene / carboxymethyl chitosan composite structure.

[0139] The difference between Comparative Example 4 and Example 3 is that the modified graphitized carbon nanotube is a graphitized carbon nanotube / polystyrene composite structure.

[0140] From Test Example 1, comparing Example 3 and Comparative Examples 1-4, it can be seen that the CNT conductive heating film prepared in the present application has excellent heat generation performance.

[0141] The above description is only a preferred embodiment of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above disclosed technical content to make equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, equivalent change and modification of the above embodiments according to the technical essence of the present application, all still belong to the scope of the technical solution of the present application.

Claims

1. A method for preparing a CNT conductive heating film, characterized in that: The preparation method comprises the following steps: (1) melt-mixing a first thermoplastic polyurethane elastomer and modified graphitized carbon nanotubes in a mass ratio of 80-85:15-20, coating, and naturally cooling to room temperature to obtain a film layer; (2) mixing the second thermoplastic polyurethane elastomer, the insulating agent, and N,N-dimethylformamide in a mass ratio of 10:0.2-0.3:80-100 at 60-80° C. under ultrasonic stirring for 6-12 h to obtain a membrane solution; (3) applying the membrane liquid to one side of the membrane layer and drying it, thereby completing the preparation; The modified graphitized carbon nanotubes in step (1) are prepared by the following steps: Step A: adding 1-1.2 parts by weight of pretreated graphitized carbon nanotubes and 8-10 parts by weight of ethylenediamine to 40-50 parts by weight of N,N-dimethylformamide, stirring and mixing under ultrasound at 55-60° C. for 40-48 hours, filtering, taking the filter residue, washing with deionized water, and finally vacuum drying at 40-80° C. until constant weight, to obtain component A; Step B: adding 1-1.5 parts by weight of component A to 50-70 parts by weight of deionized water, and then stirring and mixing under ultrasound at room temperature for 15-30 minutes to obtain component B; Step C: adding 0.5-1 parts by weight of carboxymethyl chitosan to 35-40 parts by weight of deionized water, and then stirring and mixing under ultrasonication at 30-40° C. for 10-15 minutes to obtain component C; Step D: Add component C and 0.2-0.3 parts by weight of 1,2,7,8-diepoxyoctane dropwise to component B at 70-80° C. while stirring. After all the addition is complete, continue stirring at a constant temperature for 6-8 hours, filter, collect the filter residue, wash with deionized water, and finally vacuum dry at 40-80° C. until constant weight is obtained to obtain component D; Step E: Adjust the pH of 60-80 parts by weight of an ethanol aqueous solution to 3-3.5 using an aqueous hydrochloric acid solution, then add the component D and 0.2-0.3 parts by weight of aniline, and then dropwise add 8-10 parts by weight of a 10% ammonium persulfate aqueous solution while stirring under ultrasound in an ice bath. After all the addition is complete, continue stirring at a constant temperature for 4-6 hours, let stand for 4-6 hours, filter, collect the filter residue, wash with deionized water, and finally vacuum dry at 40-80°C until constant weight. The preparation is completed.

2. The method for preparing a CNT conductive heating film according to claim 1, wherein: The pretreated graphitized carbon nanotubes in step A are prepared by the following steps: 0.8-1 parts by weight of graphitized carbon nanotubes are added to 60-80 parts by weight of a 37% hydrochloric acid aqueous solution, and then stirred for 1-2 hours in an ultrasonic bath with a power of 300-500 W at room temperature. The mixture is filtered, the filter residue is collected, and washed with deionized water. Finally, the mixture is vacuum dried at 40-80° C. until constant weight is achieved. The preparation is completed.

3. The method for preparing a CNT conductive heating film according to claim 1, wherein: The mass fraction of the hydrochloric acid aqueous solution in step E is 37%.

4. The method for preparing a CNT conductive heating film according to claim 1, wherein: The mass fraction of the ethanol aqueous solution in step E is 80-90%.

5. The method for preparing a CNT conductive heating film according to claim 1, wherein: The melt mixing in step (1) refers to stirring and mixing at 190-200°C for 10-15 minutes.

6. The method for preparing a CNT conductive heating film according to claim 1, wherein: The insulating agent in step (2) is nano-silicon dioxide.

7. The method for preparing a CNT conductive heating film according to claim 1, wherein: The drying in step (3) refers to vacuum drying at 85-90°C for 1 hour.

8. A CNT conductive heating film prepared by the preparation method according to any one of claims 1 to 7.

9. An application of a CNT conductive heating film prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The CNT conductive heating film is used in thermal insulation products.