A preparation method of shielding cotton and electromagnetic shielding darkroom

Abstract

The invention discloses a preparation method of shielding cotton and an electromagnetic shielding darkroom. The pretreated polyurethane sponge is immersed in a Ti3C2 nanosheet dispersion liquid by an impregnation method to obtain a conductive sponge with electromagnetic shielding effect. After being dried in a freeze vacuum dryer, it is used as a radiation protection layer to make an electromagnetic shielding darkroom to achieve radiation protection applications. The conductive sponge shielding darkroom prepared by the invention is simple in method, lower in cost, lighter in weight, and can control its space size, and has the characteristics of being portable and mobile. It can be used in information protection, data security, anti-electromagnetic shielding and other occasions to prevent communication eavesdropping and information theft, avoid malicious positioning and tracking, and can also reduce external electromagnetic interference to ensure the normal operation of electronic and electrical equipment in the darkroom. It has a high value of promotion and utilization.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic shielding, and mainly relates to a preparation method of shielding cotton and an electromagnetic shielding darkroom, and applies Ti3C2 nanosheets to radiation shielding. Background Art

[0002] In recent years, with the increasing number of electronic devices, the privacy and information security of mobile terminal devices have become very important. However, many devices in daily life radiate electromagnetic waves, such as mobile phones, computers, Bluetooth headsets, wireless radios and televisions. The electromagnetic waves they generate will not only interfere with the normal operation of electronic components and affect the operation of equipment, but also lead to data loss, leakage of commercial secrets, and threats to personal privacy and health. At the same time, the testing and use of some precision instruments need to avoid interference from electromagnetic waves emitted by other devices, and need to be stored in a specific safe space. Therefore, it is very necessary to absorb electromagnetic waves when needed to reduce the impact of electromagnetic waves on the surrounding environment.

[0003] At present, most commercial electromagnetic shielding materials are metal materials such as iron and silver, which have excellent performance due to their advantages such as high electrical conductivity and high magnetic permeability. Due to the different impedances between metal and air, electromagnetic waves will be reflected, and at the same time, electromagnetic waves will be attenuated during the transmission inside the metal. However, when metal is used as a shielding material, it has disadvantages such as large mass, fixed shape, complex installation structure, and high cost requirements, and its use scenarios are limited to a certain extent. Compared with metal materials, titanium carbide, as a new type of material, not only has the conductive properties of metal, but also has a two-dimensional layered stacking structure, light weight and rich surface functional groups. It can be used as a conductive material to fill the interior and surface of different porous materials. It has the advantages of strong adhesion, not easy to fall off, and resistance to bending, and is suitable for a variety of electromagnetic shielding occasions.

[0004] CN113133299A, an adjustable multi-stage shielding method for improving electromagnetic shielding effectiveness, prepares flexible self-supporting Ti3C2 films of different qualities by filtering Ti3C2 colloidal solutions of different volumes, and then accumulates the film materials to enhance the shielding effect and facilitate use as a shielding material. However, such film materials are inconvenient to prepare or process. It is necessary to find a method that can both give full play to the shielding effect of Ti3C2 materials and facilitate preparation and use. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing shielding cotton, and prepares an electromagnetic shielding darkroom using the shielding cotton.

[0006] A method for preparing shielding cotton comprises the following steps: using a Ti3C2 nanosheet dispersion liquid, dipping a flexible porous material into the dispersion liquid to allow it to undergo physical adsorption, and then taking the flexible porous material out and drying it to obtain the shielding cotton.

[0007] Preferably, the flexible porous material is selected from polyurethane sponge, cork, and fiber cloth.

[0008] Preferably, the mass fraction of Ti3C2 in the porous material is 15ω%~60ω%.

[0009] Preferably, the porous material is pretreated before immersion by ultrasonication in a mixed solution of water:ethanol=1:1 for 30 min, and then placed in an oven at 60°C for drying for 2 hours.

[0010] Preferably, the Ti3C2 nanosheet dispersion has a content of 15 mg / mL.

[0011] Preferably, the immersion includes repeated extrusion to uniformly disperse the Ti3C2 nanosheets inside and on the surface of the porous material.

[0012] Preferably, the drying is performed by vacuum drying in a freeze dryer for 72 h.

[0013] Preferably, the immersing and drying operations are repeated several times.

[0014] Preferably, the method for preparing the Ti3C2 nanosheet dispersion is as follows:

[0015] (1) LiF and 9 M HCl were mixed and stirred until LiF was completely dissolved, and Ti3AlC2 with the same mass as LiF was slowly added. The mixture was placed in a reactor and reacted at 50-70 °C for 24 h.

[0016] (2) The product was centrifuged at 3500 rpm for 5 min, washed with deionized water until pH>6, and dried under vacuum;

[0017] (3) The product obtained in step 2 was dried and dispersed in deionized water at a concentration of 15 mg / mL, and ultrasonicated at a frequency of 600 W for 1 h;

[0018] (4) The dispersion after ultrasound was centrifuged at 3500 rpm for 1 h, and the upper suspension was the ultrathin Ti3C2 nanosheet dispersion.

[0019] The present invention also provides an electromagnetic shielding darkroom, wherein the shielding cotton prepared according to the above method is cut into the shape of an unfolded diagram of a box, and the conductive sponge is covered and fixed inside the box, and openings are reserved on the box and the shielding cotton.

[0020] Beneficial effects of the present invention: The present invention has the following advantages: (1) The raw material of the present invention adopts a non-metallic nano-Ti3C2 material with light weight, conductivity and excellent adhesion effect; (2) The lining of the sponge elastomer shielding darkroom of the present invention is prepared by impregnation technology, and the thickness of the sponge can be adjusted or different concentrations of Ti3C2 dispersion can be used to achieve different shielding effects; (3) The sponge-based shielding darkroom used in the present invention is prepared by orderly folding and gluing technology, which can be customized to be folded into a desired shape and is suitable for more occasions; (4) Compared with the electromagnetic shielding darkroom made of metal, the sponge-based shielding darkroom of the present invention only contains a single layer of shielding film, which has a simpler structure, lower cost, lighter weight, foldable and easy to carry; (5) The sponge-based shielding bag of the present invention can shield a variety of signals, including Bluetooth, wireless network, 5G, etc.; (6) The polyurethane conductive sponge electromagnetic shielding darkroom of the present invention can adopt a variety of flexible substrates, including but not limited to nylon, fiber, cloth, etc.; (7) The sponge elastomer shielding darkroom of the present invention can be prepared at room temperature and has -15 o C-90 o C wide temperature operating range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional view of an actual electromagnetic shielding chamber.

[0022] Figure 2 This is a cross-sectional diagram of the electromagnetic shielding chamber.

[0023] Figure 3 The test results of electromagnetic shielding lined polyurethane sponge were immersed in 15 mg / mL dispersion for 3 times in X-band.

[0024] Figure 4 The total electromagnetic shielding performance data of 60PPI sponge after different dipping times. Note: The horizontal axis P X M Y It means: P X is the number of times the polyurethane sponge (P) is impregnated, M Y Then Y is the mass fraction of titanium carbide (M) in the conductive sponge.

[0025] Among them: 1 is the conductive sponge lining the electromagnetic shielding darkroom; 2 is the carton part; 3 is the external decoration of the carton.

[0026] Specific implementation steps:

[0027] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings.

[0028] Example 1

[0029] Pretreatment of polyurethane sponge. Cut the large area of ​​sponge with a thickness of 0.5 cm into the unfolded shape of the carton. Figure 1 The polyurethane sponge was shaped into the same shape, and ultrasonicated in a mixed solution of water: ethanol = 1:1 for 30 min, and then placed in an oven at 60°C for 2 hours to obtain a clean polyurethane sponge.

[0030] Preparation of polyurethane conductive sponge. The pretreated sponge was immersed in 250 mL of 15 mg / mL titanium carbide nanosheet dispersion, and squeezed repeatedly to make the nanosheets evenly dispersed inside and on the surface of the sponge carrier, and then placed in a freeze dryer for vacuum drying for 72 hours. After drying, a polyurethane sponge soaked with titanium carbide was obtained.

[0031] Example 2

[0032] A design of electromagnetic shielding darkroom structure, see Figure 1 , Figure 2 The conductive sponge prepared in the embodiment is glued to the inside of the unfolded surface of the carton, and then folded, the inner and outer layers are folded together into the original shape of the carton, the intersections of the surfaces are sealed with glue, and one side is reserved on the upper part for placing electronic equipment, and a simple electromagnetic shielding darkroom can be designed.

[0033] Example 3

[0034] The total shielding effectiveness tested at different immersion times is shown in the table below. Figure 3 Six experimental groups were set up. The first group of sponges was soaked once in titanium carbide dispersion and freeze-dried to obtain sample 1, numbered P1M. 10.08 , where P1 represents the polyurethane conductive sponge formed by one soaking, M 10.08 It represents the mass fraction of titanium carbide in the sample. By analogy, five other groups of experiments were set up. By setting different times of infiltration, it was found that the conductive sponge infiltrated three times had the best shielding performance.

[0035] Example 4

[0036] The test results of the conductive sponge formed by immersing the sponge in titanium carbide dispersion three times in the X-band are shown in Figure 4 The total shielding effectiveness of the conductive sponge with a volume of 22.84×10.18×5 mm in the X-band was tested by the band method and reached 85 dB, of which the absorption loss was 80 dB and the reflection loss was 5 dB, proving that the main function of the conductive sponge on electromagnetic waves is absorption, which reduces the damage caused by the secondary reflection of electromagnetic waves.

[0037] Example 5

[0038] A design of electromagnetic shielding darkroom structure, see Figure 1, Figure 2 , including an inner shielding layer, that is, a conductive sponge 3 impregnated with titanium carbide, a carton plywood layer in the middle, and an outer decorative layer 4. The shielding layer is made of a polyurethane conductive material evenly coated with a Ti3C2 dispersion, selected from sponges, fiber cloth, nylon cloth, cork, etc. The Ti3C2 dispersion is physically adsorbed on the inside and surface of the sponge carrier by an impregnation method, and is used as an inner lining after drying. The outer decorative layer uses ordinary paper-based materials. The outer layer and the middle layer, as well as the inner layer and the middle layer, are connected by glue. The three layers are folded together into the original shape of a small carton, leaving the inside empty, and the edge joints are glued with glue. An opening for loading electronic equipment is reserved, and the opening is bent to seal the darkroom. Glue is used to bond, and an electromagnetic shielding darkroom can be prepared.

[0039] Example 6

[0040] An application demonstration of an electromagnetic shielding darkroom. When the mobile phone is working normally, the electromagnetic wave darkroom is placed at the edge of the mobile phone, and the electromagnetic wave value detected is 1.26 μT. The normally working mobile phone is placed in the designed electromagnetic shielding darkroom, and the detection instrument detects the electromagnetic wave value again at the same position. At this time, the electromagnetic intensity is reduced to 0.12 μT.

[0041] Example 7

[0042] An application demonstration of an electromagnetic shielding darkroom. When the Bluetooth headset is working normally, the electromagnetic wave detector is placed at a distance from the edge of the headset, and the detected electromagnetic wave value is 0.17 μT. When the electronic watch is working normally, the electromagnetic wave detector is placed at a distance from the edge of the watch, and the detected electromagnetic wave value is 0.10 μT. The normally working Bluetooth headset and watch are placed in the designed electromagnetic shielding darkroom respectively, and the detection instrument detects the electromagnetic wave value again at the same position. At this time, the electromagnetic intensity is weakened to 0.00 μT.

[0043] The above examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

Claims

1. A method for preparing shielding cotton, characterized in that: A Ti3C2 nanosheet dispersion is used, and a flexible porous material is immersed in the dispersion by an impregnation method to perform physical adsorption. After being taken out, the flexible porous material is dried to obtain shielding cotton. The mass fraction of Ti3C2 in the flexible porous material is 15 ω% ~ 60 ω%, and the flexible porous, the Ti3C2 nanosheet dispersion content is 15 mg / mL. The material is pretreated before immersion, ultrasonicated in a mixed solution of water: ethanol = 1: 1 for 30 minutes, and then placed in an oven at 60 ° C for 2 hours. The drying is vacuum drying in a freeze dryer for 72 hours. The immersion and drying operations are repeated three times.

2. The method for preparing the shielding cotton according to claim 1, characterized in that: The flexible porous material is selected from polyurethane sponge, cork and fiber cloth.

3. The method for preparing shielding cotton according to claim 1, characterized in that: The immersion includes repeated extrusion to uniformly disperse the Ti3C2 nanosheets inside and on the surface of the flexible porous material.

4. The method for preparing shielding cotton according to claim 1, characterized in that: The preparation method of the Ti3C2 nanosheet dispersion is as follows: (1) LiF and 9 M HCl were mixed and stirred until LiF was completely dissolved, and Ti3AlC2 with the same mass as LiF was slowly added. The mixture was placed in a reactor and reacted at 50-70 °C for 24 h. (2) The product was centrifuged at 3500 rpm for 5 min, washed with deionized water until pH>6, and dried under vacuum; (3) The product obtained in step 2 was dried and dispersed in deionized water at a concentration of 10 mg / mL, and ultrasonicated at a frequency of 600 W for 1 h; (4) The dispersion after ultrasound was centrifuged at 3500 rpm for 1 h, and the upper suspension was the ultrathin Ti3C2 nanosheet dispersion.

5. An electromagnetic shielding darkroom, characterized in that: The shielding cotton prepared according to any one of claims 1 to 4 is cut into the shape of an unfolded diagram of a box, and the conductive sponge is covered and fixed inside the box, with openings and closings reserved on the box and the shielding cotton.

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