Noise reduction shielding film, preparation method and application thereof

Abstract

The invention discloses a noise reduction shielding film and a preparation method and application thereof, the noise reduction shielding film sequentially comprises a bottom film, a silicon carbide coating and a printing layer from bottom to top, and silicon carbide in the bottom film and / or the silicon carbide coating is subjected to plasma strengthening treatment. According to the method, the bottom film and / or the silicon carbide are / is treated through the plasma, and through plasma treatment, an additional combination effect can be introduced on the surface of the coating and the bottom film through the impact effect of plasma high-energy particles, so that the combination property of the bottom film and the silicon carbide coating is higher, and the stability of the noise reduction shielding layer is improved; meanwhile, compared with common silicon carbide, the silicon carbide treated by the plasma has the advantage that the electromagnetic shielding and dispersity are obviously improved. The noise reduction shielding film is good in performance and wide in application range, can be used in electromagnetic shielding equipment and can also be applied to labels through the printing layer.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic shielding films, and in particular to a noise reduction shielding film, a preparation method and application thereof. Background Art

[0002] Due to the development of science and technology and the guidance of human needs, electronic devices are developing towards smaller, lighter and more reliable directions, which requires portable electronic devices to have higher power and faster operating speed. However, when electronic devices are running at high power and high speed, they will radiate a large amount of high-frequency electromagnetic waves, thus generating electromagnetic interference. These electromagnetic waves may not only hinder the effective operation of neighboring devices, but more seriously may also pollute the ecological environment and endanger the health of organisms.

[0003] Electromagnetic shielding is one of the effective means to suppress electromagnetic interference. Attaching a film layer with electromagnetic shielding properties on the surface of electronic equipment helps to suppress electromagnetic disturbance. In order to meet the needs of electromagnetic shielding, it is necessary to improve traditional shielding materials. Among traditional shielding materials, silicon carbide has very high chemical stability. At any reasonable temperature, there is almost no diffusion of impurities inside the material. Some studies have been conducted on materials with better electromagnetic shielding prepared based on silicon carbide. For example, CN115928043A discloses a graphene / silicon carbide composite material, a preparation method thereof, and its application in electromagnetic shielding equipment. The graphene / silicon carbide composite material is prepared by laser chemical vapor deposition equipment with at least one of hexamethyldisilane, methyltrichlorosilane, silicon chloride, methane, propane and hydrogen. The material has good electromagnetic shielding performance, but the preparation conditions are relatively harsh and the equipment is relatively sophisticated, which limits industrial production. CN116926785A discloses a method for preparing a flexible silicon carbide nanofiber membrane for electromagnetic wave absorption. By means of an electrostatic spinning method, titanium acetylacetonate, yttrium acetylacetonate, and zirconium acetylacetonate are regulated as reinforcing agents to prepare a nanofiber membrane for electromagnetic wave absorption. This method can prepare a flexible shielding membrane that can be used in a variety of scenarios, but the efficiency of electrostatic spinning is not high, and reinforcing agents are not common and account for a large proportion.

[0004] In view of the problems of complex steps and expensive equipment in the current preparation of silicon carbide shielding materials, a corresponding solution needs to be provided. Summary of the invention

[0005] In order to overcome the problems existing in the prior art, the present invention provides a noise reduction shielding film, which includes a base film, a silicon carbide coating and a printing layer from bottom to top, and the silicon carbide in the base film and / or the silicon carbide coating is subjected to plasma strengthening treatment.

[0006] Furthermore, the parameters of the plasma enhanced treatment include treating for 1 to 10 minutes at a voltage peak of 10 to 20 kV using dielectric barrier discharge in a gas range of 300 to 500 mL / min of oxygen and / or argon.

[0007] Plasma strengthening treatment is to use the high energy activity of plasma to chemically react and physically deposit on the surface of the material, thereby changing the chemical properties and physical structure of the material surface to achieve the purpose of strengthening treatment. The specific steps of plasma strengthening treatment include three stages: gas discharge, plasma generation and surface treatment. First, the gas is injected into the reaction chamber of the plasma treatment machine, and the gas molecules are excited by the high-frequency electric field to ionize them into plasma. Then, under the action of the high-frequency electric field, the active substances in the plasma are activated and have the ability to chemically react and physically deposit on the surface of the material. Finally, the chemical reaction and physical effect of plasma are used to clean, activate, coat and other treatments on the surface of the material. Plasma strengthening treatment has many advantages, including lowering the processing temperature, accelerating the processing speed, improving the processing quality, enhancing the strengthening effect and reducing the processing cost.

[0008] The inventive concept of the present invention is to use plasma to treat the base film and / or silicon carbide. After the plasma treatment, the impact of high-energy plasma particles can introduce additional bonding effects between the coating and the base film surface, so that the bonding between the base film and the silicon carbide coating is stronger, and the stability of the noise reduction shielding layer is improved. At the same time, compared with ordinary silicon carbide, the electromagnetic shielding and dispersibility of silicon carbide after plasma treatment are significantly improved, so that better electromagnetic shielding performance can be achieved by adding a smaller concentration.

[0009] Furthermore, the silicon carbide coating is obtained by mixing silicon carbide or plasma-treated silicon carbide, polyvinyl pyrrolidone, and a solvent in a mass ratio of 2-5:0.05-0.1:40-60 to obtain a slurry, which is then coated on a base film and dried.

[0010] Furthermore, the particle size of the silicon carbide or plasma-treated silicon carbide is 0.05 to 2 μm.

[0011] Furthermore, the thickness of the silicon carbide coating is 0.2 to 0.5 mm;

[0012] The silicon carbide is also treated with silane;

[0013] The plasma strengthened silicon carbide is subjected to silane treatment before the plasma strengthened silicon carbide is subjected to silane treatment.

[0014] Silane treatment is a commonly used surface modification method for inorganic materials. In the present invention, there is no need to strictly limit the conditions for silane treatment. Specifically, the silanization process includes mixing a silane coupling agent, silicon carbide, and a solvent, and then collecting the insoluble matter, washing, and drying. The type of silane coupling agent does not need to be strictly limited, and it can be at least one of KH550, KH560, KH580, etc.; the amount of silane coupling agent used is preferably 0.02 to 0.5 times the mass of silicon carbide; the solvent can be at least one of water, ethanol, acetone, etc.

[0015] Further, the molecular weight of the polyvinyl pyrrolidone is 8000-200000;

[0016] The solvent includes at least one of ethyl acetate, butyl acetate and isopropyl acetate.

[0017] Nylon (PA), also known as polyamide, is a general term for thermoplastic resins containing repeated amide groups -[NHCO]- in the main chain of the molecule. Nylon has the advantages of being non-toxic, light, and having excellent mechanical strength, wear resistance, and good corrosion resistance.

[0018] Furthermore, the base film is nylon with a thickness of 0.05 to 0.3 mm.

[0019] Polyethylene terephthalate (PET) is made by ester exchange of dimethyl terephthalate with ethylene glycol or esterification of terephthalic acid with ethylene glycol to synthesize dihydroxyethyl terephthalate, and then polycondensation reaction. PET has the characteristics of high transparency, good gloss, excellent mechanical properties, high and low temperature resistance, chemical resistance, etc., and also has good thermal transfer properties.

[0020] Furthermore, the printing layer is polyethylene terephthalate with a thickness of 0.02 to 0.1 mm.

[0021] The present invention also provides a method for preparing a noise reduction shielding film, comprising:

[0022] Preparing silicon carbide slurry;

[0023] The silicon carbide slurry is coated on the base film and then dried to form a silicon carbide coating;

[0024] preparing a printed layer on the silicon carbide coating;

[0025] The silicon carbide in the base film and / or the silicon carbide coating is subjected to plasma strengthening treatment.

[0026] The present invention also provides application of the noise reduction and shielding film in electromagnetic shielding equipment.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention treats the base film and / or silicon carbide by plasma. After the plasma treatment, the impact of high-energy plasma particles can introduce additional bonding between the coating and the base film surface, making the base film more bonded to the silicon carbide coating, improving the stability of the noise reduction shielding layer, and at the same time, the electromagnetic shielding and dispersibility of the silicon carbide after plasma treatment are significantly improved compared to ordinary silicon carbide. The noise reduction shielding film of the present invention has good performance and a wide range of applications. It can be used in electromagnetic shielding equipment and can also be applied to labels through a printing layer. DETAILED DESCRIPTION

[0029] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0030] Some of the raw materials used in the embodiments of the present invention are described as follows:

[0031] PA film, model 006, thickness 0.1 mm, purchased from Shanghai Baixin New Material Technology Co., Ltd.;

[0032] Silicon carbide, black, average particle size 0.5μm, customized by Lianyungang Jiabei Silicon Carbide Co., Ltd.

[0033] Polyvinyl pyrrolidone, model K25, molecular weight 30000, purchased from Wuhan Lvjing Fenghua Biotechnology Co., Ltd.;

[0034] PET film, model X30, black, thickness 0.05 mm, purchased from Toray, Japan;

[0035] Other raw materials not mentioned are common raw materials in the art. The above content is only to help illustrate the present invention and should not be construed as a strict limitation of the present invention. Those skilled in the art can directly purchase or prepare the same / similar raw materials from the market. These contents will not be repeated in the examples.

[0036] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] A method for preparing a noise reduction shielding film, the steps are as follows:

[0039] S1, 30 g of silicon carbide, 0.8 g of polyvinyl pyrrolidone, and 500 g of isopropyl acetate were stirred and mixed at 1000 rpm for 30 min to obtain silicon carbide slurry;

[0040] S2, the silicon carbide slurry is loaded into a slot coater, and is evenly brushed on the surface of the plasma enhanced PA film through slot coating, and is fully dried in a 4-section oven at a temperature of 150°C to obtain a silicon carbide coating with a thickness of 0.2 mm;

[0041] S3. Laminating the black PET film on the surface of the silicon carbide coating by a laminating machine to obtain a noise reduction and shielding film.

[0042] Among them, the preparation method of plasma-enhanced PA film is to place the PA film in a contact plasma discharge instrument, in a gas atmosphere of oxygen and argon with a volume ratio of 1:2 at 350mL / min, use dielectric barrier discharge, and treat it for 5 minutes at a voltage peak of 20kV to obtain a plasma-enhanced PA film.

[0043] Example 2

[0044] A method for preparing a noise reduction shielding film, the steps are as follows:

[0045] S1, 30 g of silane-treated silicon carbide, 0.8 g of polyvinyl pyrrolidone, and 500 g of isopropyl acetate were stirred and mixed at 1000 rpm for 30 min to obtain silicon carbide slurry;

[0046] S2, the silicon carbide slurry is loaded into a slot coater, and is evenly brushed on the surface of the plasma enhanced PA film through slot coating, and is fully dried in a 4-section oven at a temperature of 150°C to obtain a silicon carbide coating with a thickness of 0.2 mm;

[0047] S3. Laminating the black PET film on the surface of the silicon carbide coating by a laminating machine to obtain a noise reduction and shielding film.

[0048] The preparation method of the plasma enhanced PA film is the same as that in Example 1.

[0049] The preparation method of silane-treated silicon carbide is as follows: 20g silicon carbide, 8g KH580, and 100g water are stirred at 400rpm for 2.5h, then the insoluble matter is collected by filtration, washed three times with water and anhydrous ethanol respectively, and then placed in a constant temperature oven at 120°C for 8h to obtain silane-treated silicon carbide.

[0050] Example 3

[0051] A method for preparing a noise reduction shielding film, the steps are as follows:

[0052] S1, 30 g of modified silicon carbide, 0.8 g of polyvinyl pyrrolidone, and 500 g of isopropyl acetate were stirred and mixed at 1000 rpm for 30 min to obtain silicon carbide slurry;

[0053] S2, the silicon carbide slurry is loaded into a slot coater, and is evenly brushed on the surface of the plasma enhanced PA film through slot coating, and is fully dried in a 4-section oven at a temperature of 150°C to obtain a silicon carbide coating with a thickness of 0.2 mm;

[0054] S3. Laminating the black PET film on the surface of the silicon carbide coating by a laminating machine to obtain a noise reduction and shielding film.

[0055] The preparation method of the plasma enhanced PA film is the same as that in Example 1.

[0056] The preparation method of modified silicon carbide is as follows: placing silicon carbide in a contact plasma discharge instrument, in a gas atmosphere of oxygen and argon with a volume ratio of 1:2 at 350 mL / min, using dielectric barrier discharge, and treating for 5 minutes at a voltage peak of 25 kV to obtain modified silicon carbide.

[0057] Example 4

[0058] A method for preparing a noise reduction shielding film, the steps are as follows:

[0059] S1, 30 g of modified silicon carbide, 0.8 g of polyvinyl pyrrolidone, and 500 g of isopropyl acetate were stirred and mixed at 1000 rpm for 30 min to obtain silicon carbide slurry;

[0060] S2, the silicon carbide slurry is loaded into a slot coater, and is evenly brushed on the surface of the plasma enhanced PA film through slot coating, and is fully dried in a 4-section oven at a temperature of 150°C to obtain a silicon carbide coating with a thickness of 0.2 mm;

[0061] S3. Laminating the black PET film on the surface of the silicon carbide coating by a laminating machine to obtain a noise reduction and shielding film.

[0062] The preparation method of modified silicon carbide is as follows: placing silane-treated silicon carbide in a contact plasma discharge instrument, using dielectric barrier discharge in a gas atmosphere of oxygen and argon with a volume ratio of 1:2 at 350 mL / min, and treating for 5 minutes at a voltage peak of 25 kV to obtain modified silicon carbide.

[0063] The preparation method of the plasma enhanced PA film is the same as that of Example 1; the preparation method of the silane treated silicon carbide is the same as that of Example 2.

[0064] Comparative Example 1

[0065] A method for preparing a noise reduction shielding film, the steps are as follows:

[0066] S1, 30 g of silicon carbide, 0.8 g of polyvinyl pyrrolidone, and 500 g of isopropyl acetate were stirred and mixed at 1000 rpm for 30 min to obtain silicon carbide slurry;

[0067] S2, the silicon carbide slurry is loaded into a slot coater, and is evenly brushed on the surface of the PA film through slot coating, and is fully dried in a 4-section oven at a temperature of 150°C to obtain a silicon carbide coating with a thickness of 0.2 mm;

[0068] S3. Laminating the black PET film on the surface of the silicon carbide coating by a laminating machine to obtain a noise reduction and shielding film.

[0069] Comparative Example 2

[0070] A method for preparing a noise reduction shielding film, the steps are as follows:

[0071] S1, 30 g of silane-treated silicon carbide, 0.8 g of polyvinyl pyrrolidone, and 500 g of isopropyl acetate were stirred and mixed at 1000 rpm for 30 min to obtain silicon carbide slurry;

[0072] S2, the silicon carbide slurry is loaded into a slot coater, and is evenly brushed on the surface of the PA film through slot coating, and is fully dried in a 4-section oven at a temperature of 150°C to obtain a silicon carbide coating with a thickness of 0.2 mm;

[0073] S3. Laminating the black PET film on the surface of the silicon carbide coating by a laminating machine to obtain a noise reduction and shielding film.

[0074] The preparation method of silane-treated silicon carbide is the same as that in Example 2.

[0075] Comparative Example 3

[0076] A method for preparing a noise reduction shielding film, the steps are as follows:

[0077] S1, 50 g of silicon carbide, 0.8 g of polyvinyl pyrrolidone, and 500 g of isopropyl acetate were stirred and mixed at 1000 rpm for 30 min to obtain silicon carbide slurry;

[0078] S2, the silicon carbide slurry is loaded into a slot coater, and is evenly brushed on the surface of the PA film through slot coating, and is fully dried in a 4-section oven at a temperature of 150°C to obtain a silicon carbide coating with a thickness of 0.2 mm;

[0079] S3. Laminating the black PET film on the surface of the silicon carbide coating by a laminating machine to obtain a noise reduction and shielding film.

[0080] Test Case

[0081] Referring to GB / T 1720-2020 "Paint Film Circle Test", the adhesion of the PA base film and the silicon carbide coating of the noise reduction and shielding film (not covered with PET film) of the embodiment and the comparative example was tested using a paint film circle tester, and the results are shown in Table 1. Among them, the adhesion level is divided into seven levels, represented by numbers 1 to 7, and the smaller the number, the stronger the adhesion.

[0082] Table 1 Coating adhesion results

[0083]

[0084]

[0085] From the test results in Table 1, it can be seen that the adhesion of Comparative Example 3 with a higher silicon carbide content is the worst, and the adhesion of the silicon carbide coating directly constructed with silicon carbide and polyvinyl pyrrolidone to the PA film is poor. At the same time, the silicon carbide is treated with silane, which cannot effectively enhance the adhesion performance of silicon carbide and PA film. The adhesion of the PA film and silicon carbide coating of the embodiment is significantly stronger than that of the comparative example. This is because the PA film and / or silicon carbide material are subjected to plasma strengthening treatment, and the impact of the high-energy particles of the plasma can introduce additional bonding effects on the surface of the coating and the base film, making the base film and the silicon carbide coating more bonded. At the same time, the dispersion performance of silicon carbide in the slurry is better, which suppresses the unevenness of the coating. Compared with Examples 1 to 3, Example 4 has a higher adhesion level, which shows that only by subjecting both the PA film and the silane-treated silicon carbide to plasma treatment can the adhesion between the base film and the silicon carbide coating be further improved.

[0086] The X-band is a type of electromagnetic wave with a shorter wavelength and a higher frequency. It is between microwaves and infrared rays, with a frequency range of about 8GHz to 12GHz and a wavelength range of about 25mm to 37.5mm. The shielding efficiency values ​​of the silicon carbide coatings in the embodiments and comparative examples using shielding materials were tested using a vector network analyzer. The specific sample size was 22.86mm×10.06mm×2mm, and the shielding material was mixed with molten paraffin and then loaded into a mold for curing. The results of the shielding efficiency values ​​are shown in Table 2.

[0087] Table 2 Reflection loss results

[0088]

[0089]

[0090] From the test results in Table 2, it can be seen that the use of silane to treat silicon carbide does not significantly improve the X-band electromagnetic waves, while the shielding performance of silicon carbide treated with plasma is significantly enhanced. The silanization treatment and plasma treatment have a good promoting effect, which makes the plasma-modified silane-treated silicon carbide have the strongest X-band electromagnetic wave shielding performance.

[0091] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A noise reduction shielding film, comprising, from bottom to top, a base film, a silicon carbide coating and a printing layer, characterized in that: The silicon carbide in the base film and / or the silicon carbide coating is subjected to plasma strengthening treatment.

2. The noise reduction shielding film according to claim 1, characterized in that: The parameters of the plasma strengthening treatment include treating for 1 to 10 minutes at a voltage peak of 15 to 25 kV using dielectric barrier discharge in a gas range of 300 to 500 mL / min of oxygen and / or argon.

3. The noise reduction shielding film according to claim 1, characterized in that: The silicon carbide coating is obtained by mixing silicon carbide or plasma-strengthened silicon carbide, polyvinyl pyrrolidone and a solvent in a mass ratio of 2-5:0.05-0.1:40-60 to obtain a slurry, which is then coated on a base film and dried.

4. The noise reduction shielding film according to claim 3, characterized in that: The particle size of the silicon carbide or plasma-enhanced silicon carbide is 0.05 to 2 μm; The silicon carbide is also treated with silane; The plasma strengthened silicon carbide is subjected to silane treatment before the plasma strengthened silicon carbide is subjected to silane treatment.

5. The noise reduction shielding film according to claim 3, characterized in that: The thickness of the silicon carbide coating is 0.2-0.5 mm.

6. The noise reduction shielding film according to claim 3, characterized in that: The molecular weight of the polyvinyl pyrrolidone is 8000-200000; The solvent includes at least one of ethyl acetate, butyl acetate and isopropyl acetate.

7. The noise reduction shielding film according to claim 1, characterized in that: The base film is made of nylon with a thickness of 0.05 to 0.3 mm.

8. The noise reduction shielding film according to claim 1, characterized in that: The printing layer is polyethylene terephthalate with a thickness of 0.02 to 0.1 mm.

9. A method for preparing a noise reduction shielding film, characterized in that: include, Preparing silicon carbide slurry; The silicon carbide slurry is coated on the base film and then dried to form a silicon carbide coating; preparing a printed layer on the silicon carbide coating; The silicon carbide in the base film and / or the silicon carbide coating is subjected to plasma strengthening treatment.

10. Use of the noise reduction shielding film according to any one of claims 1 to 8 in electromagnetic shielding equipment.

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