An ANF / MXene electromagnetic shielding paper, its preparation method and application

Abstract

This invention belongs to the field of electromagnetic shielding materials technology, and discloses an ANF / MXene electromagnetic shielding paper, its preparation method, and its application. The method includes: pre-screening Ti3AlC2 powder; wherein the transverse particle size of the pre-treated Ti3AlC2 is greater than 20-25 μm; preparing an MXene aqueous dispersion using lithium fluoride, hydrochloric acid solution, and the pre-screened Ti3AlC2; using dimethyl sulfoxide for solvent replacement to obtain an MXene / DMSO dispersion; mixing the MXene / DMSO dispersion with the ANF / DMSO dispersion to obtain an ANF / MXene sol, and coating it onto a substrate using an adjustable doctor blade, followed by soaking and drying to obtain the ANF / MXene electromagnetic shielding paper. The material of this invention has a highly ordered layered structure and a uniform and dense internal structure, exhibiting excellent electromagnetic shielding effectiveness and mechanical strength.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding materials technology, and specifically relates to an ANF / MXene electromagnetic shielding paper, its preparation method, and its application. Background Technology

[0002] With the development and widespread application of electronic devices, their electromagnetic environment has become more complex, and the interference between electronic devices is becoming more and more serious. Electromagnetic shielding materials can block the propagation path of electromagnetic waves, and high-performance electromagnetic shielding materials have become crucial for resisting electromagnetic wave pollution in electronic devices.

[0003] Currently, commonly used electromagnetic shielding materials include metallic materials or conductive polymer composite materials composed of a polymer matrix and conductive fillers and their hybrids. Among them, metallic materials are limited in their widespread application in new electronic devices due to their high density, susceptibility to corrosion, and difficulty in processing. In contrast, conductive polymer composite materials have the advantages of being lightweight, easy to process, and corrosion resistant, and have been extensively studied and used in lightweight electromagnetic interference shielding materials.

[0004] Aramid nanofibers (ANFs) are lightweight, flexible, heat-resistant, and chemically resistant, making them suitable for applications in military, security, and composite material reinforcement. They can also be used as matrix materials for flexible composites. However, ANFs have high insulation properties, limiting their application in lightweight electronic devices. MXenes, on the other hand, are a newly emerging two-dimensional (2D) transition material composed of transition metal carbides / nitrides. They possess unique metal-like high conductivity and a layered structure, along with excellent corrosion resistance, and are widely used in electromagnetic shielding, supercapacitors, and gas sensors. Therefore, constructing composite materials by interacting MXenes with ANFs is expected to both enhance their electromagnetic shielding effectiveness and improve their mechanical properties.

[0005] Currently, when constructing composite materials using the interaction between MXene and ANF, the non-uniform size of the MXene nanosheets prepared by traditional methods prevents them from forming a dense stack, and the irregular size easily leads to a large interfacial resistance, which limits the improvement of the conductivity of the composite material and causes serious damage to the mechanical strength of the composite material at high addition levels. Summary of the Invention

[0006] In view of the technical problems existing in the prior art, the present invention provides an ANF / MXene electromagnetic shielding paper, its preparation method and application, to solve the technical problem that the existing MXene has limited effect on improving the conductivity of composite materials and causes serious damage to the mechanical strength of composite materials when added in high amounts.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a method for preparing ANF / MXene electromagnetic shielding paper, comprising the following steps:

[0009] The original Ti3AlC2 powder was pre-screened to obtain pre-screened Ti3AlC2; wherein the transverse size of the pre-screened Ti3AlC2 particles was greater than 20-25 μm.

[0010] MXene aqueous dispersion was prepared using lithium fluoride, hydrochloric acid solution, and the pre-screened Ti3AlC2.

[0011] Solvent replacement of MXene aqueous dispersion with dimethyl sulfoxide was used to obtain MXene / DMSO dispersion;

[0012] The MXene / DMSO dispersion was mixed with the ANF / DMSO dispersion to obtain ANF / MXene sol;

[0013] The ANF / MXene sol was applied to the substrate using an adjustable scraper, and then soaked and dried to obtain ANF / MXene electromagnetic shielding paper.

[0014] Furthermore, the process of pre-screening the original Ti3AlC2 powder to obtain pre-screened Ti3AlC2 is as follows:

[0015] The original Ti3AlC2 powder was dispersed in deionized water, allowed to stand, and then separated to obtain the largest phase particles. The dispersion, standing, and separation operations were repeated three times to obtain the pre-screened Ti3AlC2.

[0016] Furthermore, the concentration of the MXene / DMSO dispersion is 1-2 wt%, and the concentration of the ANF / DMSO dispersion is 1-2 wt%.

[0017] Furthermore, the mass fraction of MXene in the ANF / MXene sol is 20-80 wt%.

[0018] Furthermore, in the process of applying the ANF / MXene sol onto the substrate using an adjustable squeegee, the height of the adjustable squeegee from the substrate is 0.2-0.3 mm, and the squeegee speed is 8-10 mm / s.

[0019] Furthermore, during the soaking treatment, the water is soaked in deionized water for 12-14 hours.

[0020] Furthermore, the drying process is carried out under vacuum conditions at a temperature of 90-110℃.

[0021] The present invention also provides an ANF / MXene electromagnetic shielding paper, which is prepared using the aforementioned method for preparing ANF / MXene electromagnetic shielding paper.

[0022] Furthermore, the thickness of the ANF / MXene electromagnetic shielding paper is 0.014-0.016 mm; the conductivity of the ANF / MXene electromagnetic shielding paper is 87.3-59232.3 S / m, the electromagnetic shielding effectiveness is 16.2-56.4 dB, and the tensile strength is 66.3-205.4 MPa.

[0023] The present invention also provides an application of ANF / MXene electromagnetic shielding paper, which is used as an electromagnetic shielding material in electronic devices.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention provides an ANF / MXene electromagnetic shielding paper and its preparation method. By pre-screening the original Ti3AlC2 powder, uniform large-sized MXene nanosheets with a lateral particle size greater than 20-25 μm and high conductivity are obtained, thereby reducing the interfacial resistance caused by irregular size and thus endowing the composite material with excellent conductivity. Secondly, blade coating is used as an effective strategy to construct a tightly stacked and highly aligned nanolayer structure, enabling the production of large-area, large-size ANF / MXene electromagnetic shielding paper, which is beneficial for large-scale industrial production. Simultaneously, the network framework structure and abundant hydrogen bond interactions between ANF and MXene nanosheets are utilized to achieve… While retaining the excellent mechanical properties of aramid nanofibers, their electromagnetic shielding performance can be effectively improved, solving the problem of incompatibility between mechanical properties and functionality. The ANF / MXene electromagnetic shielding paper of this invention has a highly ordered layered structure and a uniform and dense internal structure. ANF fibers adhere to the MXene nanosheets, forming a stable "brick-and-mortar" structure, exhibiting good electromagnetic shielding effectiveness and mechanical strength. Its comprehensive performance is excellent and it can be applied in the field of electromagnetic shielding. The ANF / MXene electromagnetic shielding paper has an electrical conductivity of 87.3-59232.3 S / m, an electromagnetic shielding effectiveness of 16.2-56.4 dB, and a tensile strength of 66.3-205.4 MPa. Attached Figure Description

[0026] Figure 1 SEM images of MXene slices before pre-screening;

[0027] Figure 2 This is a SEM image of the pre-screened MXene slices from Example 1;

[0028] Figure 3 The image shown is a cross-sectional SEM image of the ANF / MXene electromagnetic shielding paper prepared in the example. Detailed Implementation

[0029] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0030] This invention provides a method for preparing ANF / MXene electromagnetic shielding paper, comprising the following steps:

[0031] Step 1: Pre-screen the original Ti3AlC2 powder to obtain pre-screened Ti3AlC2. Specifically, disperse the original Ti3AlC2 powder in deionized water to obtain a dispersion. After the dispersion is allowed to stand for 80-127 seconds, remove the upper suspension to separate the largest phase particles. Repeat the dispersion, standing, and separation operations three times to obtain the pre-screened Ti3AlC2. The liquid level of the deionized water in the dispersion is 10 cm, and the transverse size of the pre-treated Ti3AlC2 particles is greater than 20-25 μm.

[0032] Step 2: Add lithium fluoride to hydrochloric acid solution and stir continuously until completely dissolved to obtain lithium fluoride / hydrochloric acid system; add the pre-screened Ti3AlC2 from Step 1 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath for stirring reaction to obtain reactants; wash the reactants until the pH is 6-7 to obtain MXene aqueous dispersion; wherein the oil bath temperature is 35-40℃ and the reaction time is 36-48h.

[0033] Step 3: Solvent displacement of the MXene aqueous dispersion using dimethyl sulfoxide to obtain an MXene / DMSO dispersion; specifically, the MXene aqueous dispersion is centrifuged to obtain a precipitate; the precipitate is dispersed in DMSO, centrifuged again, and the precipitate is obtained again. This process is repeated at least three times to obtain a solvent-displaced precipitate; then, the solvent-displaced precipitate is redissolved in DMSO and ultrasonically treated to obtain an MXene / DMSO dispersion; wherein the concentration of the MXene / DMSO dispersion is 1-2 wt%.

[0034] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 1-2 wt%.

[0035] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 20-80 wt%.

[0036] Step 6: Apply the ANF / MXene sol to the substrate using an adjustable scraper. Immerse the substrate coated with ANF / MXene sol in deionized water for 12-14 hours to obtain a smooth black gel. The substrate is a glass plate. The height of the adjustable scraper from the substrate is 0.2-0.3 mm, and the scraping speed is 8-10 mm / s.

[0037] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.014-0.016 mm; wherein the drying temperature is 90-110℃.

[0038] Preparation principle:

[0039] The preparation method of the ANF / MXene electromagnetic shielding paper described in this invention utilizes the network framework structure and abundant hydrogen bond interactions between ANF and MXene nanosheets to effectively improve their electromagnetic shielding performance while retaining the excellent mechanical properties of aramid nanofibers. Specifically, by pre-screening the original Ti3AlC2 powder, uniform large-sized MXene nanosheets with a lateral particle size greater than 20-25 μm and high conductivity are obtained, thereby reducing the interfacial resistance caused by irregular size and thus endowing the composite material with excellent conductivity. It should be noted that, due to the conventional MXene... The uneven size of the MXene nanosheets prevents them from forming a dense stack, and the irregular size easily leads to a large interfacial resistance, limiting their ability to improve the conductivity of the composite material. Pre-screening yields uniform large-sized MXene nanosheets with high conductivity, reducing the interfacial resistance caused by the irregular size and thus endowing the composite paper with excellent conductivity. Secondly, blade coating is used as an effective strategy to construct a tightly stacked and highly aligned nanolayer structure. Compared with the traditional vacuum filtration method, blade coating can obtain large-area, large-sized ANF / MXene electromagnetic shielding paper, which is conducive to large-scale industrial production.

[0040] The ANF / MXene electromagnetic shielding paper of this invention has a uniform and dense internal structure, exhibiting high strength and high electromagnetic shielding effectiveness, and can be applied in the field of electromagnetic shielding; wherein, the ANF / MXene electromagnetic shielding paper has an electrical conductivity of 87.3-59232.3 S / m, an electromagnetic shielding effectiveness of 16.2-56.4 dB, and a tensile strength of 66.3-205.4 MPa.

[0041] Example 1

[0042] This embodiment 1 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0043] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 127s, remove the upper suspension to separate the largest phase particles larger than 20μm. Repeat the dispersion, standing and separation operations three times to obtain the pre-screened Ti3AlC2.

[0044] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 35°C for stirring and reaction for 36h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0045] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 20 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and repeat the process at least three times to obtain a solvent-replaced precipitate; then, redissolve the solvent-replaced precipitate in DMSO and sonicate it for 40 min to obtain an MXene / DMSO dispersion with a concentration of 1 wt%.

[0046] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 1 wt%.

[0047] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 20 wt%.

[0048] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 12 hours to obtain a smooth black gel. The adjustable scraper is 0.2 mm above the glass plate, and the scraping speed is 8 mm / s.

[0049] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.014 mm; wherein the drying temperature is 90℃.

[0050] Performance testing:

[0051] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 1 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 87.3 S / m, the electromagnetic shielding effectiveness was 16.2 dB, and the tensile strength was 205.4 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0052] As attached Figure 1-2 As shown, attached Figure 1 The image shows SEM images of MXene sections before screening, with appendix. Figure 2 The image provided is a SEM image of the pre-screened MXene slices from Example 1; compared with the attached image... Figure 1-2 As can be seen, compared with the MXene flakes before pre-screening, the MXene flakes after pre-screening have significantly increased lateral size and are more uniform in size.

[0053] As attached Figure 3 As shown, attached Figure 3 The attached image shows a cross-sectional SEM image of the ANF / MXene electromagnetic shielding paper prepared in Example 1; from the attached image... Figure 3 As can be seen, the ANF / MXene electromagnetic shielding paper has a highly ordered layered structure, and the fibers adhere to the MXene nanosheets to form a stable "brick-and-mortar" structure, which effectively improves the mechanical strength of the composite material.

[0054] Example 2

[0055] This embodiment 2 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0056] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 81s, remove the upper suspension to separate the largest phase particles larger than 25μm. Repeat the dispersion, standing and separation operation three times to obtain the pre-screened Ti3AlC2.

[0057] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 40℃ for stirring and reaction for 48h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0058] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 50 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and obtain a new precipitate. Repeat this process at least three times to obtain a solvent-replaced precipitate; then, redissolve the solvent-replaced precipitate in DMSO and sonicate it for 50 min to obtain an MXene / DMSO dispersion with a concentration of 2 wt%.

[0059] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 2wt%.

[0060] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 20 wt%.

[0061] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 14 hours to obtain a smooth black gel. The adjustable scraper is 0.25 mm above the glass plate, and the scraping speed is 8 mm / s.

[0062] Step 7: Under vacuum conditions, the black gel is dried to obtain an ANF / MXene electromagnetic shielding paper with a thickness of 0.015 mm; wherein the drying temperature is 90℃.

[0063] Performance testing:

[0064] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 2 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 97.3 S / m, the electromagnetic shielding effectiveness was 17.5 dB, and the tensile strength was 219.5 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0065] Example 3

[0066] This embodiment 3 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0067] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 127s, remove the upper suspension to separate the largest phase particles larger than 20μm. Repeat the dispersion, standing and separation operations three times to obtain the pre-screened Ti3AlC2.

[0068] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 35°C for stirring and reaction for 36h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0069] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 50 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and repeat the process at least three times to obtain a solvent-replaced precipitate; then, redissolve the solvent-replaced precipitate in DMSO and sonicate it for 30 min to obtain a 2 wt% MXene / DMSO dispersion.

[0070] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 2wt%.

[0071] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 40 wt%.

[0072] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 14 hours to obtain a smooth black gel. The adjustable scraper is 0.25 mm above the glass plate, and the scraping speed is 8 mm / s.

[0073] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.015 mm; wherein the drying temperature is 100℃.

[0074] Performance testing:

[0075] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 3 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 437.3 S / m, the electromagnetic shielding effectiveness was 32.2 dB, and the tensile strength was 215.4 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0076] Example 4

[0077] This embodiment 4 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0078] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 127s, remove the upper suspension to separate the largest phase particles larger than 25μm. Repeat the dispersion, standing and separation operations three times to obtain the pre-screened Ti3AlC2.

[0079] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 40℃ for stirring and reaction for 48h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0080] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 40 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and repeat the process at least three times to obtain a solvent-replaced precipitate; then, redissolve the solvent-replaced precipitate in DMSO and sonicate it for 30 min to obtain a 2 wt% MXene / DMSO dispersion.

[0081] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 2wt%.

[0082] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 40 wt%.

[0083] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 14 hours to obtain a smooth black gel. The adjustable scraper is 0.3 mm above the glass plate, and the scraping speed is 8 mm / s.

[0084] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.016 mm; wherein the drying temperature is 100℃.

[0085] Performance testing:

[0086] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 4 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 447.5 S / m, the electromagnetic shielding effectiveness was 35.2 dB, and the tensile strength was 219.8 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0087] Example 5

[0088] This embodiment 5 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0089] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 81s, remove the upper suspension to separate the largest phase particles larger than 25μm. Repeat the dispersion, standing and separation operation three times to obtain the pre-screened Ti3AlC2.

[0090] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 40℃ for stirring and reaction for 48h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0091] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 20 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and repeat the process at least three times to obtain a solvent-replaced precipitate; then, redissolve the solvent-replaced precipitate in DMSO and sonicate it for 50 min to obtain a 2 wt% MXene / DMSO dispersion.

[0092] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 2wt%.

[0093] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 60 wt%.

[0094] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 12 hours to obtain a smooth black gel. The adjustable scraper is 0.25 mm above the glass plate, and the scraping speed is 8 mm / s.

[0095] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.015 mm; wherein the drying temperature is 110℃.

[0096] Performance testing:

[0097] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 5 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 9345.3 S / m, the electromagnetic shielding effectiveness was 49.2 dB, and the tensile strength was 57.4 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0098] Example 6

[0099] This embodiment 6 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0100] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 81s, remove the upper suspension to separate the largest phase particles larger than 20μm. Repeat the dispersion, standing and separation operations three times to obtain the pre-screened Ti3AlC2.

[0101] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 35°C for stirring and reaction for 36h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0102] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 20 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and repeat the process at least three times to obtain a solvent-replaced precipitate; then, redissolve the solvent-replaced precipitate in DMSO and sonicate it for 30 min to obtain an MXene / DMSO dispersion with a concentration of 1 wt%.

[0103] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 1 wt%.

[0104] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 60 wt%.

[0105] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 12 hours to obtain a smooth black gel. The adjustable scraper is 0.3 mm above the glass plate, and the scraping speed is 10 mm / s.

[0106] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.016 mm; wherein the drying temperature is 110℃.

[0107] Performance testing:

[0108] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 6 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 9232.3 S / m, the electromagnetic shielding effectiveness was 47.4 dB, and the tensile strength was 55.4 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0109] Example 7

[0110] This embodiment 7 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0111] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 81s, remove the upper suspension to separate the largest phase particles larger than 25μm. Repeat the dispersion, standing and separation operation three times to obtain the pre-screened Ti3AlC2.

[0112] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 40℃ for stirring and reaction for 48h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0113] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 30 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and repeat the process at least three times to obtain a solvent-displaced precipitate; then, redissolve the solvent-displaced precipitate in DMSO and sonicate it for 40 min to obtain an MXene / DMSO dispersion with a concentration of 2 wt%.

[0114] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 2wt%.

[0115] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 80 wt%.

[0116] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 12 hours to obtain a smooth black gel. The adjustable scraper is 0.25 mm above the glass plate, and the scraping speed is 10 mm / s.

[0117] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.015 mm; wherein the drying temperature is 110℃.

[0118] Performance testing:

[0119] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 7 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 59232.3 S / m, the electromagnetic shielding effectiveness was 56.4 dB, and the tensile strength was 69.4 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0120] Example 8

[0121] This embodiment 8 provides a method for preparing ANF / MXene electromagnetic shielding paper, including the following steps:

[0122] Step 1: Disperse the original Ti3AlC2 powder in 50mL of deionized water, ensuring that the liquid level of the deionized water is 10cm, to obtain a dispersion; after the dispersion has been allowed to stand for 127s, remove the upper suspension to separate the largest phase particles larger than 20μm. Repeat the dispersion, standing and separation operations three times to obtain the pre-screened Ti3AlC2.

[0123] Step 2: Add 4.8g of lithium fluoride to 45mL of 9mol / L hydrochloric acid solution and stir continuously until completely dissolved to obtain a lithium fluoride / hydrochloric acid system; add 3g of pre-screened Ti3AlC2 to the lithium fluoride / hydrochloric acid system and transfer it to an oil bath at 35°C for stirring and reaction for 36h to obtain the reactant; wash the reactant until the pH is 6-7 to obtain MXene aqueous dispersion.

[0124] Step 3: Centrifuge the MXene aqueous dispersion at 8000 rpm for 50 min to obtain a precipitate; disperse the precipitate in DMSO, centrifuge to separate it, and repeat the process at least three times to obtain a solvent-replaced precipitate; then, redissolve the solvent-replaced precipitate in DMSO and sonicate it for 30 min to obtain a 2 wt% MXene / DMSO dispersion.

[0125] Step 4: Mix chopped para-aramid fibers (PPTA), potassium hydroxide (KOH), deionized water, and dimethyl sulfoxide (DMSO) solvent, and stir continuously to carry out the reaction until the solution turns reddish-brown and viscous, thus obtaining an ANF / DMSO dispersion; wherein the concentration of the ANF / DMSO dispersion is 2wt%.

[0126] Step 5: Mix the ANF / DMSO dispersion with the MXene / DMSO dispersion to obtain a uniform black ANF / MXene sol; wherein the mass fraction of MXene in the ANF / MXene sol is 80 wt%.

[0127] Step 6: Apply the ANF / MXene sol to a glass plate using an adjustable scraper. Immerse the glass plate coated with ANF / MXene sol in deionized water for 12 hours to obtain a smooth black gel. The adjustable scraper is 0.3 mm above the glass plate, and the scraping speed is 10 mm / s.

[0128] Step 7: Under vacuum conditions, the black gel is dried to obtain ANF / MXene electromagnetic shielding paper with a thickness of 0.016 mm; wherein the drying temperature is 110℃.

[0129] Performance testing:

[0130] The performance of the ANF / MXene electromagnetic shielding paper prepared in Example 8 was tested. The test results were as follows: the conductivity of the ANF / MXene electromagnetic shielding paper was 56892.3 S / m, the electromagnetic shielding effectiveness was 53.3 dB, and the tensile strength was 66.3 MPa. Therefore, the ANF / MXene electromagnetic shielding paper has good electromagnetic shielding effectiveness and mechanical strength, and its comprehensive performance is excellent.

[0131] In this invention, flexible aramid nanofibers with excellent mechanical properties are used as the matrix and combined with highly conductive, uniform, large-sized MXene. A doctor blade coating process is used to prepare large-area ANF / MXene electromagnetic shielding paper with excellent electromagnetic shielding performance and mechanical properties. Compared with the conventional vacuum filtration method, large-area ANF / MXene electromagnetic shielding paper can be obtained, which helps to realize large-scale preparation and reduce production costs.

[0132] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for preparing ANF / MXene electromagnetic shielding paper, characterized in that, Includes the following steps: The original Ti3AlC2 powder was pre-screened to obtain pre-screened Ti3AlC2; wherein the transverse size of the pre-screened Ti3AlC2 particles was greater than 20-25 μm. MXene aqueous dispersion was prepared using lithium fluoride, hydrochloric acid solution, and the pre-screened Ti3AlC2. Solvent replacement of MXene aqueous dispersion with dimethyl sulfoxide was used to obtain MXene / DMSO dispersion; The MXene / DMSO dispersion was mixed with the ANF / DMSO dispersion to obtain ANF / MXene sol; The ANF / MXene sol was coated onto the substrate using an adjustable scraper, and then soaked and dried to obtain ANF / MXene electromagnetic shielding paper. The process of pre-screening the original Ti3AlC2 powder to obtain pre-screened Ti3AlC2 is as follows: The original Ti3AlC2 powder was dispersed in deionized water, allowed to stand, and then separated to obtain the largest phase particles. The dispersion, standing, and separation operations were repeated three times to obtain the pre-screened Ti3AlC2. The process for preparing MXene aqueous dispersion using lithium fluoride, hydrochloric acid solution, and the pre-screened Ti3AlC2 is as follows: Lithium fluoride was added to a hydrochloric acid solution and stirred until completely dissolved to obtain a lithium fluoride / hydrochloric acid system. Pre-screened Ti3AlC2 was added to the lithium fluoride / hydrochloric acid system and transferred to an oil bath for stirring and reaction to obtain a reactant. The reactant was washed until the pH reached 6-7 to obtain an MXene aqueous dispersion. The oil bath temperature was 35-40℃ and the reaction time was 36-48h.

2. The method for preparing ANF / MXene electromagnetic shielding paper according to claim 1, characterized in that, The concentration of the MXene / DMSO dispersion is 1-2 wt%, and the concentration of the ANF / DMSO dispersion is 1-2 wt%.

3. The method for preparing an ANF / MXene electromagnetic shielding paper according to claim 1, characterized in that, The mass fraction of MXene in the ANF / MXene sol is 20-80 wt%.

4. The method for preparing ANF / MXene electromagnetic shielding paper according to claim 1, characterized in that, The process of applying the ANF / MXene sol onto the substrate using an adjustable squeegee, wherein the adjustable squeegee is 0.2-0.3 mm above the substrate and the squeegee speed is 8-10 mm / s.

5. The method for preparing an ANF / MXene electromagnetic shielding paper according to claim 1, characterized in that, During the soaking treatment, the water is soaked in deionized water for 12-14 hours.

6. The method for preparing an ANF / MXene electromagnetic shielding paper according to claim 1, characterized in that, During the drying process, drying is carried out under vacuum conditions at a temperature of 90-110℃.

7. An ANF / MXene electromagnetic shielding paper, characterized in that, It is prepared using the preparation method of ANF / MXene electromagnetic shielding paper as described in any one of claims 1-6.

8. The ANF / MXene electromagnetic shielding paper according to claim 7, characterized in that, The thickness of the ANF / MXene electromagnetic shielding paper is 0.014-0.016 mm; the conductivity of the ANF / MXene electromagnetic shielding paper is 87.3-59232.3 S / m, the electromagnetic shielding effectiveness is 16.2-56.4 dB, and the tensile strength is 66.3-205.4 MPa.

9. The application of the ANF / MXene electromagnetic shielding paper as described in any one of claims 7-8, characterized in that, The application of the ANF / MXene electromagnetic shielding paper as an electromagnetic shielding material in electronic devices.

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