ANF / MXene-PMIA electromagnetic shielding composite paper and preparation method and application thereof

Abstract

The invention belongs to the field of electromagnetic shielding materials, and particularly relates to ANF / MXene-PMIA electromagnetic shielding composite paper and a preparation method and application thereof. Mixing the ANF / DMSO dispersion liquid and the MXene / DMSO dispersion liquid, and carrying out ultrasonic treatment to obtain a mixed dispersion liquid; based on a directional blade coating technology, uniformly blade-coating the surface of meta-aramid paper with the mixed dispersion liquid, and carrying out standing treatment to obtain ANF / MXene-PMIA composite gel; carrying out proton exchange treatment, so as to obtain ANF / MXene-PMIA composite gel after proton exchange; and drying in vacuum to obtain the ANF / MXene-PMIA electromagnetic shielding composite paper. The ANF / MXene-PMIA electromagnetic shielding composite paper prepared by the invention has excellent electrical conductivity and mechanical properties, shows a good electromagnetic shielding function, and can be applied to electronic equipment as an electromagnetic shielding material.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic shielding materials, and in particular relates to an ANF / MXene-PMIA electromagnetic shielding composite paper and a preparation method and application thereof. Background Art

[0002] Meta-aramid (PMIA) paper is widely used in aerospace, rail transit and other fields due to its excellent electrical insulation properties, high strength and chemical corrosion resistance. However, with the large-scale popularization of high-speed communications and the Internet of Everything technology, the electromagnetic environment faced by trains, aircraft and other stealth equipment is becoming increasingly complex. Therefore, the development of meta-aramid paper with electromagnetic shielding properties is of great significance to the operation of equipment.

[0003] Currently, the existing technology usually introduces highly conductive fillers into meta-aramid paper based on a simple blending method to give it electromagnetic shielding properties. Due to the intrinsic insulation properties of meta-aramid paper, its high electromagnetic shielding effectiveness can only be achieved by relying on the content of highly conductive fillers. A large amount of simple blending fillers will greatly damage the mechanical strength and flexibility of meta-aramid paper, and will also cause serious waste of resources. Summary of the Invention

[0004] In response to the technical problems existing in the prior art, the present invention provides an ANF / MXene-PMIA electromagnetic shielding composite paper and its preparation method and application, so as to solve the technical problem in the prior art that when highly conductive fillers are introduced into meta-aramid paper based on a simple blending method, the mechanical strength and flexibility of the meta-aramid paper will be greatly damaged, and serious waste of resources will be caused.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides a method for preparing ANF / MXene-PMIA electromagnetic shielding composite paper, comprising: Using wet papermaking process, meta-aramid paper is obtained; The ANF / DMSO dispersion and the MXene / DMSO dispersion were mixed and ultrasonically treated to obtain a mixed dispersion; Based on the directional blade coating technology, the mixed dispersion was evenly coated on the surface of the meta-aramid paper and allowed to stand to obtain the ANF / MXene-PMIA composite gel. Performing proton exchange treatment on the ANF / MXene-PMIA composite gel to obtain a proton-exchanged ANF / MXene-PMIA composite gel; The proton-exchanged ANF / MXene-PMIA composite gel was vacuum dried to obtain ANF / MXene-PMIA electromagnetic shielding composite paper.

[0006] Furthermore, the process of obtaining meta-aramid paper by wet papermaking process includes: The meta-aramid short fibers are cleaned with a sodium dodecylbenzenesulfonate solution and dried to obtain cleaned meta-aramid short fibers; The meta-aramid fibrid is deflaked, and after adding the cleaned meta-aramid short fibers and polyethylene oxide, the fibers are deflaked again to obtain pulp; The pulp is formed, cold pressed and dried to obtain meta-aramid paper.

[0007] Furthermore, the mass fraction of the meta-aramid fibrids is 50 wt.%-80 wt.%, and the mass fraction of the meta-aramid chopped fibers after washing is 20 wt.%-50 wt.%.

[0008] Furthermore, the preparation process of the ANF / DMSO dispersion includes: Potassium hydroxide, water, para-aramid short fibers and dimethyl sulfoxide were mixed and stirred in a water bath to obtain an ANF / DMSO dispersion.

[0009] Furthermore, the ANF / DMSO dispersion and the MXene / DMSO dispersion were mixed and ultrasonically treated to obtain a mixed dispersion, and the absolute dry weight ratio of ANF and MXene was (1-5): (5-9).

[0010] Furthermore, the ANF / DMSO dispersion and the MXene / DMSO dispersion are mixed and ultrasonically treated to obtain a mixed dispersion. The ultrasonic power is 150-300 W and the ultrasonic time is 5-30 min.

[0011] Furthermore, based on the directional scraping technology, the mixed dispersion was evenly scraped onto the surface of the meta-aramid paper and allowed to stand for treatment. In the process of obtaining the ANF / MXene-PMIA composite gel, the height of the scraper was adjusted to obtain ANF / MXene-PMIA composite gels of different thicknesses; wherein, the height of the scraper was 200-800 μm.

[0012] Furthermore, the proton-exchanged ANF / MXene-PMIA composite gel is vacuum dried to obtain the ANF / MXene-PMIA electromagnetic shielding composite paper. The vacuum drying temperature is 60-120° C. and the drying time is 10-120 min.

[0013] The present invention also provides an ANF / MXene-PMIA electromagnetic shielding composite paper, which is prepared using the preparation method of the ANF / MXene-PMIA electromagnetic shielding composite paper.

[0014] The present invention also provides an application of an ANF / MXene-PMIA electromagnetic shielding composite paper, and the application of the ANF / MXene-PMIA electromagnetic shielding composite paper as an electromagnetic shielding material in electronic equipment.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The preparation method of the ANF / MXene-PMIA electromagnetic shielding composite paper provided by the present invention is based on the transition metal carbide Ti3C2T x By combining the high conductivity of MXene and the easy film-forming properties of aramid nanofibers, a lightweight and flexible ANF / MXene-PMIA electromagnetic shielding composite paper was prepared using PMIA paper as a substrate through directional blade coating technology. The ANF / MXene-PMIA electromagnetic shielding composite paper has both excellent conductivity and mechanical properties, and exhibits good electromagnetic shielding function. It can be used as an electromagnetic shielding material in electronic devices, and has potential significance in practical applications such as smart electronic devices and communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a PMIA side photo of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1; Figure 2 This is a side photo of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1; Figure 3 This is a diagram showing the flexibility of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions, and beneficial effects solved by this application more clearly understood, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application; it is obvious that the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of this application.

[0019] The present invention provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Prepare meta-aramid (PMIA) paper using a wet papermaking process. Specifically, the process of preparing PMIA paper includes: PMIA chopped fibers were placed in a 1.2×10 -3 mol / L sodium dodecylbenzene sulfonate (LAS) solution and washed at 60°C for 30 minutes; then, dried in an oven to obtain washed PMIA chopped fibers; the meta-aramid fibrils are placed in a standard fiber disintegrator and deflaked at 12000-20000 r / min; then, the washed PMIA chopped fibers and polyethylene oxide (PEO) are added and deflaked again at 8000-20000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid fibrils is 50wt.%-80wt.%, and the mass fraction of the washed meta-aramid chopped fibers is 20wt.%-50wt.%; then, the pulp is poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web is cold pressed by a press for 1-5 minutes, and then placed in a dryer for drying at 90-120°C for 10-20 minutes to obtain PMIA paper.

[0020] Step 2: Prepare an ANF / DMSO dispersion using a chemical splitting method. Specifically, potassium hydroxide is dissolved in deionized water, para-aramid (PPTA) chopped fibers are added, and then dimethyl sulfoxide (DMSO) is added. The mixture is mechanically stirred in a water bath until it turns dark red, thereby obtaining an ANF / DMSO dispersion.

[0021] Step 3: Mix lithium fluoride, hydrochloric acid solution and Ti3AlC2, carry out etching reaction, and obtain a mixed solution after reaction; wash the mixed solution after reaction until it is neutral; then, perform water bath ultrasonic treatment and centrifuge to obtain a MXene / H2O dispersion; use DMSO to replace the solvent of the MXene / H2O dispersion to obtain a MXene / DMSO dispersion.

[0022] Step 4: According to the absolute dry weight ratio of ANF to MXene (1-5): (5-9), the ANF / DMSO dispersion and the MXene / DMSO dispersion are mixed and ultrasonically treated to obtain a mixed dispersion; wherein the ultrasonic power is 150-300 W and the ultrasonic time is 5-30 min.

[0023] Step 5: Based on the directional scraping technology, the mixed dispersion is evenly scraped on the surface of the meta-aramid paper, and allowed to stand for 1-7 minutes to obtain the ANF / MXene-PMIA composite gel; wherein, the ANF / MXene-PMIA composite gel is obtained by adjusting the height of the scraper; preferably, the height of the scraper is 200-800 μm.

[0024] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 4-12 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0025] Step 7: vacuum-dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 60-120° C. for 10-120 min to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0026] Preparation principle: The preparation method of the ANF / MXene-PMIA electromagnetic shielding composite paper described in the present invention comprises mixing an ANF / DMSO dispersion and a MXene / DMSO dispersion, and uniformly coating the mixture on the surface of the PMIA paper using a directional scraping technique to introduce MXene into the surface of the PMIA paper, thereby forming a double-layer structure of ANF / MXene and PMIA paper. By constructing the double-layer structure, the composite paper can achieve high electromagnetic shielding performance while retaining its good mechanical properties. Secondly, based on the directional scraping technique, the MXene nanosheets and the ANF can be given good orientation, which is beneficial to reducing the interface resistance between the MXene nanosheets and promoting the PMIA paper to be more resistant to electromagnetic field. An efficient conductive network is formed on the surface; at the same time, the highly oriented ANF gives the composite paper excellent tensile strength and toughness; in addition, the use of DMSO as a coating solvent is conducive to its surface etching of the aramid fiber, thereby promoting the formation of a good interface bonding between ANF, MXene and PMIA paper; in addition, through directional coating technology, a double-layer structure of ANF / MXene and PMIA paper is constructed, and ANF and MXene are used to construct a "brick-mud" structure in the ANF / MXene layer, which can prevent the MXene nanosheets from falling off on the one hand, and avoid the MXene layer from oxidative failure due to contact with air on the other hand, which is beneficial to the long-term stability of electromagnetic shielding performance.

[0027] In the present invention, PMIA paper is used as the substrate, based on the transition metal carbide Ti3C2T xThe high conductivity of (MXene) and the easy film-forming properties of aramid nanofibers are used to prepare a lightweight and flexible ANF / MXene-PMIA electromagnetic shielding composite paper through directional blade coating technology; the prepared ANF / MXene-PMIA electromagnetic shielding composite paper has excellent conductivity and mechanical properties, and exhibits good electromagnetic shielding function. It can be used as an electromagnetic shielding material in electronic devices, and has potential significance in practical applications such as smart electronic devices and communications.

[0028] Example 1 This embodiment 1 provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Place PMIA chopped fibers on a 1.2×10 -3 mol / L LAS solution, washed at 60 ° C for 30 minutes; then, dried in an oven to obtain cleaned PMIA short fibers; the meta-aramid precipitated fibers were placed in a standard fiber disintegrator and deflaked at 15000 r / min; then, the cleaned PMIA short fibers and PEO were added and deflaked again at 20000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid precipitated fibers was 70wt.%, and the mass fraction of the cleaned meta-aramid short fibers was 30wt.%; then, the pulp was poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web was cold pressed for 3 minutes using a press, and then placed in a dryer for drying at 120 ° C for 10 minutes to obtain PMIA paper; wherein the basis weight of PMIA paper is 70g / m 2 .

[0029] Step 2: Dissolve 11.25 g of KOH in 21.25 mL of deionized water, add 7.5 g of PPTA chopped fibers; then add 460.0 g of DMSO and mechanically stir in a water bath at 40 ° C for 48 h until it turns dark red to obtain an ANF / DMSO dispersion with a concentration of 1.5 wt.%.

[0030] Step 3. Add 4.8 g of lithium fluoride (LiF) to 60 mL of 9 mol / L hydrochloric acid solution and stir thoroughly until completely dissolved to obtain a fluorine-containing solution; add 3 g of MAX precursor (Ti3AlC2) to the fluorine-containing solution and stir and etch at 35 ° C for 24 hours to obtain a mixed solution after the reaction; wash the mixed solution after the reaction with deionized water until neutral and ultrasonically treat it in a water bath at 200 W for 120 minutes; then, centrifuge at 3500 rpm for 60 minutes to obtain a supernatant, that is, a MXene / H2O dispersion; replace the water in the MXene / H2O dispersion with DMSO to obtain a MXene / DMSO dispersion with a mass percentage of 2%.

[0031] Step 4: Mix the ANF / DMSO dispersion and the MXene / DMSO dispersion in a ratio of 2:8 based on the absolute dry weight of ANF and MXene; then, ultrasonicate at 300 W for 10 min to obtain a mixed dispersion.

[0032] Step 5: Adjust the height of the scraper to 800 μm, and use the scraper to evenly spread the mixed dispersion on the surface of the PMIA paper. Let it stand for 2 minutes to obtain the ANF / MXene-PMIA composite gel.

[0033] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 12 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0034] Step 7: vacuum dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 60° C. for 120 min to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0035] Performance Monitoring: The performance of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in this Example 1 was tested, and the test results were as follows: the thickness of the ANF / MXene-PMIA electromagnetic shielding composite paper was 71 μm, the electrical conductivity was 2519.3 S / cm, the electromagnetic shielding effectiveness was 48.6 dB, and the tensile strength was 131.6 MPa; it can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1 can exhibit excellent electromagnetic shielding performance and mechanical properties.

[0036] As attached Figure 1 As shown, attached Figure 1 The PMIA side photo of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1 is given in the attached figure. Figure 1 It can be seen from the figure that the surface of the coated ANF / MXene layer is smooth, and MXene and ANF are evenly distributed.

[0037] As attached Figure 2 As shown, attached Figure 2 The ANF / MXene side photo of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1 is given in the attached figure. Figure 2It can be seen that the surface of PMIA paper is flat and smooth, and is light yellow. Under the action of DMSO etching, some MXene nanosheets and ANF penetrate into the interior of PMIA paper; therefore, a small amount of black MXene nanosheets can be observed on one side of PMIA; this shows that in the ANF / MXene-PMIA electromagnetic shielding composite paper, the ANF / MXene mixture can form a good interface bonding with PMIA.

[0038] As attached Figure 3 As shown, attached Figure 3 The flexibility display effect diagram of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1 is given in the attached figure. Figure 3 It can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 1 is thin, soft, and can be curled arbitrarily; the reason is that due to the good film-forming properties of ANF and MXene, and the close bonding with PMIA, the ANF / MXene-PMIA electromagnetic shielding composite paper still maintains good mechanical properties.

[0039] Example 2 This embodiment 2 provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Place PMIA chopped fibers on a 1.2×10 -3 mol / L LAS solution, washed at 60 ° C for 30 minutes; then, dried in an oven to obtain cleaned PMIA short fibers; the meta-aramid precipitated fibers were placed in a standard fiber disintegrator and deflaked at 12000 r / min; then, the cleaned PMIA short fibers and PEO were added and deflaked again at 8000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid precipitated fibers was 50wt.%, and the mass fraction of the cleaned meta-aramid short fibers was 50wt.%; then, the pulp was poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web was cold pressed by a press for 5 minutes, and then placed in a dryer for drying at 90 ° C for 20 minutes to obtain PMIA paper; wherein the basis weight of PMIA paper is 70g / m 2 .

[0040] Step 2: Dissolve 11.25 g of KOH in 21.25 mL of deionized water, add 7.5 g of PPTA chopped fibers; then add 460.0 g of DMSO and mechanically stir in a water bath at 40 ° C for 48 h until it turns dark red to obtain an ANF / DMSO dispersion with a concentration of 1.5 wt.%.

[0041] Step 3. Add 4.8 g of LiF to 60 mL of 9 mol / L hydrochloric acid solution and stir thoroughly until completely dissolved to obtain a fluorine-containing solution; add 3 g of MAX precursor (Ti3AlC2) to the fluorine-containing solution and stir and etch at 35 ° C for 48 hours to obtain a mixed solution after the reaction; wash the mixed solution after the reaction with deionized water until neutral and ultrasonically treat it in a water bath at 150 W for 150 minutes; then, centrifuge at 5000 rpm for 30 minutes to obtain a supernatant, that is, a MXene / H2O dispersion; replace the water in the MXene / H2O dispersion with DMSO to obtain a MXene / DMSO dispersion with a mass percentage of 2%.

[0042] Step 4: Mix the ANF / DMSO dispersion and the MXene / DMSO dispersion in a ratio of 1:9 based on the absolute dry weight of ANF and MXene; then, ultrasonicate at 150 W for 5 min to obtain a mixed dispersion.

[0043] Step 5: Adjust the height of the scraper to 600 μm, and use the scraper to evenly spread the mixed dispersion on the surface of the PMIA paper. Let it stand for 7 minutes to obtain the ANF / MXene-PMIA composite gel.

[0044] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 4 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0045] Step 7: vacuum dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 90° C. for 60 min to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0046] Performance Monitoring: The performance of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 2 was tested, and the test results were as follows: the thickness of the ANF / MXene-PMIA electromagnetic shielding composite paper was 60 μm, the electrical conductivity was 2276.8 S / cm, the electromagnetic shielding effectiveness was 41.7 dB, and the tensile strength was 117.4 MPa; it can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 2 can exhibit excellent electromagnetic shielding performance and mechanical properties.

[0047] Example 3 This embodiment 3 provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Place PMIA chopped fibers on a 1.2×10 -3mol / L LAS solution, washed at 60 ° C for 30 minutes; then, dried in an oven to obtain cleaned PMIA short fibers; the meta-aramid precipitated fibers were placed in a standard fiber disintegrator and deflaked at 20000 r / min; then, the cleaned PMIA short fibers and PEO were added and deflaked again at 15000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid precipitated fibers was 80wt.%, and the mass fraction of the cleaned meta-aramid short fibers was 20wt.%; then, the pulp was poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web was cold pressed by a press for 3 minutes, and then placed in a dryer for drying at 100 ° C for 18 minutes to obtain PMIA paper; wherein the basis weight of PMIA paper is 70g / m 2 .

[0048] Step 2: Dissolve 11.25 g of KOH in 21.25 mL of deionized water, add 7.5 g of PPTA chopped fibers; then add 460.0 g of DMSO and mechanically stir in a water bath at 40 ° C for 48 h until it turns dark red to obtain an ANF / DMSO dispersion with a concentration of 1.5 wt.%.

[0049] Step 3. Add 4.8 g of LiF to 60 mL of 9 mol / L hydrochloric acid solution and stir thoroughly until completely dissolved to obtain a fluorine-containing solution; add 3 g of MAX precursor (Ti3AlC2) to the fluorine-containing solution and stir and etch at 35 ° C for 12 hours to obtain a mixed solution after the reaction; wash the mixed solution after the reaction with deionized water until neutral and ultrasonically treat it in a water bath at 90W for 30 minutes; then, centrifuge at 4500 rpm for 45 minutes to obtain a supernatant, that is, a MXene / H2O dispersion; use DMSO to replace the water in the MXene / H2O dispersion to obtain a MXene / DMSO dispersion with a mass percentage of 2%.

[0050] Step 4: Mix the ANF / DMSO dispersion and the MXene / DMSO dispersion in a ratio of 5:5 based on the absolute dry weight of ANF and MXene; then, ultrasonicate at 250 W for 30 min to obtain a mixed dispersion.

[0051] Step 5: Adjust the height of the scraper to 450 μm, and use the scraper to evenly spread the mixed dispersion on the surface of the PMIA paper. Let it stand for 1 minute to obtain the ANF / MXene-PMIA composite gel.

[0052] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 8 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0053] Step 7: vacuum dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 120° C. for 10 minutes to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0054] Performance Monitoring: The performance of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 3 was tested, and the test results were as follows: the thickness of the ANF / MXene-PMIA electromagnetic shielding composite paper was 47 μm, the electrical conductivity was 1815.1 S / cm, the electromagnetic shielding effectiveness was 36.6 dB, and the tensile strength was 97.5 MPa; it can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 3 can exhibit excellent electromagnetic shielding performance and mechanical properties.

[0055] Example 4 This embodiment 4 provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Place PMIA chopped fibers on a 1.2×10 -3 mol / L LAS solution, washed at 60 ° C for 30 minutes; then, dried in an oven to obtain cleaned PMIA short fibers; the meta-aramid precipitated fibers were placed in a standard fiber disintegrator and deflaked at 18000 r / min; then, the cleaned PMIA short fibers and PEO were added and deflaked again at 10000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid precipitated fibers was 60wt.%, and the mass fraction of the cleaned meta-aramid short fibers was 40wt.%; then, the pulp was poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web was cold pressed for 2 minutes using a press, and then placed in a dryer for drying at 110 ° C for 15 minutes to obtain PMIA paper; wherein the basis weight of PMIA paper is 70g / m 2 .

[0056] Step 2: Dissolve 11.25 g of KOH in 21.25 mL of deionized water, add 7.5 g of PPTA chopped fibers; then add 460.0 g of DMSO and mechanically stir in a water bath at 40 ° C for 48 h until it turns dark red to obtain an ANF / DMSO dispersion with a concentration of 1.5 wt.%.

[0057] Step 3. Add 4.8 g of LiF to 60 mL of 9 mol / L hydrochloric acid solution and stir thoroughly until completely dissolved to obtain a fluorine-containing solution; add 3 g of MAX precursor (Ti3AlC2) to the fluorine-containing solution and stir and etch at 35 ° C for 36 hours to obtain a mixed solution after the reaction; wash the mixed solution after the reaction with deionized water until neutral and ultrasonically treat it in a water bath at 180W for 90 minutes; then, centrifuge at 3000 rpm for 90 minutes to obtain a supernatant, that is, a MXene / H2O dispersion; use DMSO to replace the water in the MXene / H2O dispersion to obtain a MXene / DMSO dispersion with a mass percentage of 2%.

[0058] Step 4: Mix the ANF / DMSO dispersion and the MXene / DMSO dispersion in a ratio of 2:8 based on the absolute dry weight of ANF and MXene; then, ultrasonicate at 200 W for 25 min to obtain a mixed dispersion.

[0059] Step 5: Adjust the height of the scraper to 200 μm, and use the scraper to evenly spread the mixed dispersion on the surface of the PMIA paper. Let it stand for 5 minutes to obtain the ANF / MXene-PMIA composite gel.

[0060] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 10 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0061] Step 7: vacuum dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 80° C. for 90 minutes to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0062] Performance Monitoring: The performance of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in this Example 4 was tested, and the test results were as follows: the thickness of the ANF / MXene-PMIA electromagnetic shielding composite paper was 32 μm, the electrical conductivity was 1440.9 S / cm, the electromagnetic shielding effectiveness was 30.2 dB, and the tensile strength was 74.9 MPa; it can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 4 can exhibit excellent electromagnetic shielding performance and mechanical properties.

[0063] Example 5 This embodiment 5 provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Place PMIA chopped fibers on a 1.2×10 -3mol / L LAS solution, washed at 60 ° C for 30 minutes; then, dried in an oven to obtain cleaned PMIA short fibers; the meta-aramid precipitated fibers were placed in a standard fiber disintegrator and deflaked at 12000 r / min; then, the cleaned PMIA short fibers and PEO were added and deflaked again at 12000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid precipitated fibers was 50wt.%, and the mass fraction of the cleaned meta-aramid short fibers was 50wt.%; then, the pulp was poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web was cold pressed by a press for 4 minutes, and then placed in a dryer for drying at 100 ° C for 20 minutes to obtain PMIA paper; wherein the basis weight of PMIA paper is 70g / m 2 .

[0064] Step 2: Dissolve 11.25 g of KOH in 21.25 mL of deionized water, add 7.5 g of PPTA chopped fibers; then add 460.0 g of DMSO and mechanically stir in a water bath at 40 ° C for 48 h until it turns dark red to obtain an ANF / DMSO dispersion with a concentration of 1.5 wt.%.

[0065] Step 3. Add 4.8 g of LiF to 60 mL of 9 mol / L hydrochloric acid solution and stir thoroughly until completely dissolved to obtain a fluorine-containing solution; add 3 g of MAX precursor (Ti3AlC2) to the fluorine-containing solution and stir and etch at 35 ° C for 30 hours to obtain a mixed solution after the reaction; wash the mixed solution after the reaction with deionized water until neutral and ultrasonically treat it in a water bath at 120W for 60 minutes; then, centrifuge at 4000 rpm for 60 minutes to obtain a supernatant, that is, a MXene / H2O dispersion; replace the water in the MXene / H2O dispersion with DMSO to obtain a MXene / DMSO dispersion with a mass percentage of 2%.

[0066] Step 4: Mix the ANF / DMSO dispersion and the MXene / DMSO dispersion in a ratio of 3:7 based on the absolute dry weight of ANF and MXene; then, ultrasonicate at 300 W for 18 min to obtain a mixed dispersion.

[0067] Step 5: Adjust the height of the scraper to 300 μm, and use the scraper to evenly spread the mixed dispersion on the surface of the PMIA paper. Let it stand for 3 minutes to obtain the ANF / MXene-PMIA composite gel.

[0068] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 6 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0069] Step 7: vacuum dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 105° C. for 30 minutes to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0070] Performance Monitoring: The performance of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 5 was tested, and the test results were as follows: the thickness of the ANF / MXene-PMIA electromagnetic shielding composite paper was 39 μm, the electrical conductivity was 1612.3 S / cm, the electromagnetic shielding effectiveness was 32.8 dB, and the tensile strength was 67.1 MPa; it can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 5 can exhibit excellent electromagnetic shielding performance and mechanical properties.

[0071] Example 6 This Example 6 provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Place PMIA chopped fibers on a 1.2×10 -3 mol / L LAS solution, washed at 60 ° C for 30 minutes; then, dried in an oven to obtain cleaned PMIA short fibers; the meta-aramid precipitated fibers were placed in a standard fiber disintegrator and deflaked at 20000 r / min; then, the cleaned PMIA short fibers and PEO were added and deflaked again at 20000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid precipitated fibers was 60wt.%, and the mass fraction of the cleaned meta-aramid short fibers was 40wt.%; then, the pulp was poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web was cold pressed by a press for 5 minutes, and then placed in a dryer for drying at 120 ° C for 18 minutes to obtain PMIA paper; wherein the basis weight of PMIA paper is 70g / m 2 .

[0072] Step 2: Dissolve 11.25 g of KOH in 21.25 mL of deionized water, add 7.5 g of PPTA chopped fibers; then add 460.0 g of DMSO and mechanically stir in a water bath at 40 ° C for 48 h until it turns dark red to obtain an ANF / DMSO dispersion with a concentration of 1.5 wt.%.

[0073] Step 3. Add 4.8 g of LiF to 60 mL of 9 mol / L hydrochloric acid solution and stir thoroughly until completely dissolved to obtain a fluorine-containing solution; add 3 g of MAX precursor (Ti3AlC2) to the fluorine-containing solution and stir and etch at 35 ° C for 24 hours to obtain a mixed solution after the reaction; wash the mixed solution after the reaction with deionized water until neutral and ultrasonically treat it in a water bath at 180W for 90 minutes; then, centrifuge at 4000 rpm for 90 minutes to obtain a supernatant, that is, a MXene / H2O dispersion; replace the water in the MXene / H2O dispersion with DMSO to obtain a MXene / DMSO dispersion with a mass percentage of 2%.

[0074] Step 4: Mix the ANF / DMSO dispersion and the MXene / DMSO dispersion in a ratio of 4:6 based on the absolute dry weight of ANF and MXene; then, ultrasonicate at 250 W for 10 min to obtain a mixed dispersion.

[0075] Step 5: Adjust the height of the scraper to 600 μm, and use the scraper to evenly spread the mixed dispersion on the surface of the PMIA paper. Let it stand for 7 minutes to obtain the ANF / MXene-PMIA composite gel.

[0076] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 12 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0077] Step 7: vacuum dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 60° C. for 120 min to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0078] Performance Monitoring: The performance of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 6 was tested, and the test results were as follows: the thickness of the ANF / MXene-PMIA electromagnetic shielding composite paper was 60 μm, the electrical conductivity was 2276.8 S / cm, the electromagnetic shielding effectiveness was 41.7 dB, and the tensile strength was 117.4 MPa; it can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 6 can exhibit excellent electromagnetic shielding performance and mechanical properties.

[0079] Example 7 This embodiment 7 provides a method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper, comprising the following steps: Step 1: Place PMIA chopped fibers on a 1.2×10-3 mol / L LAS solution, washed at 60 ° C for 30 minutes; then, dried in an oven to obtain cleaned PMIA short fibers; the meta-aramid precipitated fibers were placed in a standard fiber disintegrator and deflaked at 15000 r / min; then, the cleaned PMIA short fibers and PEO were added and deflaked again at 12000 r / min to obtain pulp; wherein the mass fraction of the meta-aramid precipitated fibers was 80wt.%, and the mass fraction of the cleaned meta-aramid short fibers was 20wt.%; then, the pulp was poured into a paper sheet former for dehydration and forming to obtain a wet paper web; the wet paper web was cold pressed by a press for 5 minutes, and then placed in a dryer for drying at 110 ° C for 10 minutes to obtain PMIA paper; wherein the basis weight of PMIA paper is 70g / m 2 .

[0080] Step 2: Dissolve 11.25 g of KOH in 21.25 mL of deionized water, add 7.5 g of PPTA chopped fibers; then add 460.0 g of DMSO and mechanically stir in a water bath at 40 ° C for 48 h until it turns dark red to obtain an ANF / DMSO dispersion with a concentration of 1.5 wt.%.

[0081] Step 3. Add 4.8 g of LiF to 60 mL of 9 mol / L hydrochloric acid solution and stir thoroughly until completely dissolved to obtain a fluorine-containing solution; add 3 g of MAX precursor (Ti3AlC2) to the fluorine-containing solution and stir and etch at 35 ° C for 24 hours to obtain a mixed solution after the reaction; wash the mixed solution after the reaction with deionized water until neutral and ultrasonically treat it in a water bath at 150W for 60 minutes; then, centrifuge at 4500 rpm for 60 minutes to obtain a supernatant, that is, a MXene / H2O dispersion; replace the water in the MXene / H2O dispersion with DMSO to obtain a MXene / DMSO dispersion with a mass percentage of 2%.

[0082] Step 4: Mix the ANF / DMSO dispersion and the MXene / DMSO dispersion in a ratio of 3:7 based on the absolute dry weight of ANF and MXene; then, ultrasonicate at 150 W for 30 min to obtain a mixed dispersion.

[0083] Step 5: Adjust the height of the scraper to 450 μm, and use the scraper to evenly spread the mixed dispersion on the surface of the PMIA paper. Let it stand for 3 minutes to obtain the ANF / MXene-PMIA composite gel.

[0084] Step 6: Place the ANF / MXene-PMIA composite gel in deionized water for proton exchange treatment for 8 hours to obtain the proton-exchanged ANF / MXene-PMIA composite gel.

[0085] Step 7: vacuum dry the proton-exchanged ANF / MXene-PMIA composite gel at a vacuum drying temperature of 105° C. for 60 min to obtain an ANF / MXene-PMIA electromagnetic shielding composite paper.

[0086] Performance Monitoring: The performance of the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in this Example 7 was tested, and the test results were as follows: the thickness of the ANF / MXene-PMIA electromagnetic shielding composite paper was 47 μm, the electrical conductivity was 1815.3 S / cm, the electromagnetic shielding effectiveness was 36.6 dB, and the tensile strength was 97.5 MPa; it can be seen that the ANF / MXene-PMIA electromagnetic shielding composite paper prepared in Example 7 can exhibit excellent electromagnetic shielding performance and mechanical properties.

[0087] The preparation method of the ANF / MXene-PMIA electromagnetic shielding composite paper described in the present invention is based on the principles of directional scraping and solvent etching, and a mixture of ANF / DMSO dispersion and MXene / DMSO dispersion is uniformly scraped on the surface of PMIA paper to construct a double-layer structure of ANF / MXene and PMIA paper, so as to facilitate the formation of an efficient conductive network on the surface of PMIA paper, and at the same time make the PMIA paper have excellent tensile strength and toughness; wherein, by introducing DMSO as a scraping solvent and utilizing the principle of solvent etching, a good interface bonding is effectively promoted between ANF\MXene and PMIA paper; in addition, with PMIA paper independently as a substrate, ANF / MXene is introduced into the surface of PMIA paper by directional scraping technology, providing the composite paper with high electromagnetic shielding performance, so that the composite paper has excellent mechanical properties, electromagnetic shielding performance and environmental stability, and has broad application prospects in aerospace, communications, intelligent manufacturing and other fields.

[0088] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention.

Claims

1. A method for preparing ANF / MXene-PMIA electromagnetic shielding composite paper, characterized in that: include: Using wet papermaking process, meta-aramid paper is obtained; The ANF / DMSO dispersion and the MXene / DMSO dispersion were mixed and ultrasonically treated to obtain a mixed dispersion; Based on the directional blade coating technology, the mixed dispersion was evenly coated on the surface of the meta-aramid paper and allowed to stand to obtain the ANF / MXene-PMIA composite gel. Performing proton exchange treatment on the ANF / MXene-PMIA composite gel to obtain a proton-exchanged ANF / MXene-PMIA composite gel; The proton-exchanged ANF / MXene-PMIA composite gel was vacuum dried to obtain ANF / MXene-PMIA electromagnetic shielding composite paper.

2. The method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 1, characterized in that: The process of obtaining meta-aramid paper using the wet papermaking process includes: The meta-aramid short fibers are cleaned with a sodium dodecylbenzenesulfonate solution and dried to obtain cleaned meta-aramid short fibers; The meta-aramid fibrid is deflaked, and after adding the cleaned meta-aramid short fibers and polyethylene oxide, the fibers are deflaked again to obtain pulp; The pulp is formed, cold pressed and dried to obtain meta-aramid paper.

3. The method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 2, characterized in that: The mass fraction of the meta-aramid fibrids is 50wt.%-80wt.%, and the mass fraction of the meta-aramid chopped fibers after washing is 20wt.%-50wt.%.

4. The method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 1, characterized in that: The preparation process of ANF / DMSO dispersion includes: Potassium hydroxide, water, para-aramid short fibers and dimethyl sulfoxide were mixed and stirred in a water bath to obtain an ANF / DMSO dispersion.

5. The method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 1, characterized in that: In the process of mixing and ultrasonically treating the ANF / DMSO dispersion and the MXene / DMSO dispersion to obtain the mixed dispersion, the absolute dry weight ratio of ANF and MXene is (1-5): (5-9).

6. The method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 1, characterized in that: The ANF / DMSO dispersion and the MXene / DMSO dispersion are mixed and ultrasonically treated to obtain a mixed dispersion. The ultrasonic power is 150-300 W and the ultrasonic time is 5-30 min.

7. The method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 1, characterized in that: Based on the directional scraping technology, the mixed dispersion is evenly scraped onto the surface of the meta-aramid paper and left to stand for treatment. In the process of obtaining the ANF / MXene-PMIA composite gel, the height of the scraper is adjusted to obtain ANF / MXene-PMIA composite gels of different thicknesses; wherein, the height of the scraper is 200-800μm.

8. The method for preparing an ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 1, characterized in that: The proton-exchanged ANF / MXene-PMIA composite gel is vacuum dried to obtain the ANF / MXene-PMIA electromagnetic shielding composite paper. The vacuum drying temperature is 60-120° C. and the drying time is 10-120 min.

9. An ANF / MXene-PMIA electromagnetic shielding composite paper, characterized in that: The ANF / MXene-PMIA electromagnetic shielding composite paper is prepared using the preparation method of claim 1.

10. The use of the ANF / MXene-PMIA electromagnetic shielding composite paper according to claim 9, characterized in that: The ANF / MXene-PMIA electromagnetic shielding composite paper is used as an electromagnetic shielding material in electronic devices.

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