Polyester fabric full-band electromagnetic shielding material and preparation method thereof

Abstract

The application relates to the technical field of electromagnetic shielding, and discloses a preparation method of a polyester fabric full-frequency electromagnetic shielding material, which comprises the following steps: S1, pretreatment: taking the polyester fabric, placing the polyester fabric in a soaping liquid, and heating soaping; S2, alkali treatment: placing the polyester fabric after soaping in a mixed liquid of a cationic surfactant and alkali, heating soaking; S3, modification treatment: placing the polyester fabric in a modification liquid, soaking, drying, and heating treatment again; S4, activation treatment: placing the modified polyester fabric in an ionic palladium solution, adjusting pH, soaking, cleaning, and then placing the polyester fabric in a reducing agent for reaction; S5, surface metal plating: sequentially carrying out copper plating and soft magnetic alloy plating treatment on the surface of the activated polyester fabric; and S6, processing and forming, so as to obtain the polyester fabric full-frequency electromagnetic shielding material. The application utilizes the excellent electric conduction and magnetic conduction performance of the polyester fabric, and prepares the electromagnetic shielding material which has good electromagnetic shielding effect, good material mechanical performance and large size.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic shielding, in particular to a polyester fabric full-band electromagnetic shielding material and a preparation method thereof. BACKGROUND

[0002] Electromagnetic interference (EMI) and electromagnetic compatibility (EMC) problems caused by electromagnetic waves can interfere with electronic instruments, equipment systems, and even affect their normal work, and electromagnetic wave pollution can also endanger human health. With the development and application of electromagnetic pulse and related technologies, electromagnetic pulse weapons have become a new type of weapon for precise and direct attack on the aforementioned key instruments and equipment systems. Electromagnetic pulses can cause temporary or permanent damage to related systems, seriously threatening information security and human health.

[0003] In view of the above electromagnetic pollution, electromagnetic shielding is usually used to handle it, which uses shielding materials to reflect, absorb and guide electromagnetic energy flow, and blocks or attenuates the propagation of electromagnetic signals and energy inside and outside a specific area. According to its principle, it can be divided into electric field shielding, magnetic field shielding (including low frequency magnetic field and high frequency magnetic field) and electromagnetic field shielding. The commonly used electromagnetic shielding refers to electromagnetic field shielding.

[0004] Therefore, it is of great practical significance to prepare electromagnetic shielding materials with wide electromagnetic field frequency spectrum range and good shielding effect. Due to its excellent electromagnetic shielding performance, permalloy is used in electromagnetic shielding and electromagnetic compatibility scenes of aerospace and advanced weapons and equipment. However, permalloy cannot be directly coated on the surface of the equipment or system that needs to be implemented electromagnetic protection, but needs to be made into protective materials for specific application. However, due to the poor processing performance of permalloy, it is difficult to prepare large-size protective material products, and the rigidity is too high, which limits its application in flexible environment.

[0005] For example, the patent with publication number CN114525028A provides a kind of adjustable polymer-based porous electromagnetic shielding material and preparation method, first EG / Fe3O4 Composite material is prepared;Deionized water, triethanolamine, foam stabilizer and polyether polyol are sequentially added to EG / Fe3O4 Composite material and mixed uniformly, then stannous octoate is added and dispersed uniformly, then toluene diisocyanate is added and stirred, then poured into a mold and applied pressure, and finally the mold is dried to obtain a polymer-based porous electromagnetic shielding material. Although this method can prepare flexible electromagnetic shielding materials, the final molding of the material depends highly on the mold, and the size and shape are limited by the mold, so it is not possible to prepare flexible shielding materials with super large size or arbitrary processing shape.

[0006] For example, the patent with publication number CN114561805A provides a flexible substrate of carbon felt or hydrophilic carbon cloth, the size of the flexible substrate is related to the shieldable frequency spectrum, but the applicable frequency spectrum does not completely cover the commonly used frequency band, especially the low frequency band, and the size is relatively single; in addition, the material preparation needs to be subjected to thermal shock treatment at 1100-1300 DEG C, which has high energy consumption and complex process, and is not suitable for large-scale industrial production.

[0007] Therefore, the existing flexible electromagnetic shielding materials mainly have the following problems: (1) the flexibility and processability of the material are difficult to balance. Using the existing materials to prepare electromagnetic shielding products, either the process is difficult, or a specific mold is needed, or the shielding performance is poor. (2) The flexibility and shielding performance of the material are difficult to balance. The shielding effect of permalloy is good, but the flexibility is poor; the polymer or carbon-based material as a substrate meets the flexibility requirement, but cannot achieve full-band shielding. (3) The size of the finished product is single, and in complex application scenarios, the structure of the product that can be used is limited. Although the existing technology can prepare flexible electromagnetic shielding finished products, it is often difficult to meet the demand for secondary processing according to the application scenario or the demand for ultra-large size flexible material.

[0008] In summary, although the related technical means of flexible electromagnetic shielding materials have been proposed, their feasibility in practical scenarios is poor, and the performance of the material in all aspects is difficult to balance or balance. SUMMARY

[0009] The present application aims to solve the technical problems of:

[0010] Although the related technical means of flexible electromagnetic shielding materials have been proposed, their feasibility in practical scenarios is poor. Specifically, using existing flexible electromagnetic shielding materials to prepare related products has the problems of difficult process, need for special mold, or poor electromagnetic shielding performance; if permalloy is used, although the shielding effect is good, the flexibility is poor; if a polymer or carbon-based material is used, the basic flexibility requirement can be met, but full-band electromagnetic shielding cannot be achieved; in addition, the existing flexible electromagnetic shielding materials have single product size, and it is difficult to meet the demand for secondary processing.

[0011] The technical scheme adopted by the present application is:

[0012] The present application provides a preparation method of a polyester fabric full-band electromagnetic shielding material, comprising the following steps:

[0013] S1 pretreatment: take the polyester fabric, place it in a soaping liquid, heat soaping, and wash;

[0014] S2 alkali treatment: place the soaped polyester fabric in a mixture of cationic surfactant and alkali, and heat soak;

[0015] S3 modification treatment: The polyester fabric is then placed in the modification solution, soaked, dried, and then heated to 150-160℃ for heat treatment to obtain the modified polyester fabric.

[0016] S4 Activation Treatment: The modified polyester fabric is placed in an ionic palladium solution, the pH value is adjusted to alkaline, and the fabric is soaked and washed to obtain the activated polyester fabric.

[0017] S5 surface metallization: Copper plating and soft magnetic alloy plating are performed on the surface of activated polyester fabric to obtain metallized polyester fabric.

[0018] S6 processes metallized polyester fabric into shape to obtain a full-frequency electromagnetic shielding material made of polyester fabric.

[0019] Preferably, in step S1, the soaping solution includes sodium dodecyl sulfate and sodium hydroxide solution.

[0020] Preferably, in step S1, the soap boiling temperature is controlled at 90-100℃.

[0021] Preferably, in step S2, during the heating and soaking process, the heating temperature is controlled at 60-80℃ and the soaking time is 20-60 minutes.

[0022] Preferably, in step S3, the soaking time is controlled to be 8-20 minutes.

[0023] Preferably, in step S4, the ionic palladium solution includes PdCl2, a stabilizer, NH4Cl, and ethylenediamine, and Pd... 2+ The concentration is 0.05-0.5 g / L.

[0024] Preferably, in step S4, after washing, the fabric is placed in a dimethylaminoborane solution for a reduction reaction to obtain activated polyester fabric.

[0025] Preferably, in step S5, the thickness of the copper plating layer is controlled to be 0.001-0.08 mm, and the thickness of the soft magnetic alloy plating layer is controlled to be 0.001-0.05 mm.

[0026] The polyester fabric full-frequency electromagnetic shielding material prepared by the above preparation method can be used for electromagnetic shielding and electromagnetic compatibility under various environmental conditions.

[0027] The beneficial effects of the present application are reflected in:

[0028] The full-band electromagnetic shielding material of polyester fabric prepared by the technical means of this invention utilizes its excellent electrical and magnetic conductivity properties. The magnetic loss is composed of eddy current loss and hysteresis loss. Under the action of an external alternating electromagnetic field, the free electrons in the metal on the surface of the polyester fiber and the soft magnetic alloy film oscillate and generate oscillating current, which then converts the energy of the electromagnetic wave into heat energy and is thus dissipated. It can achieve an electromagnetic shielding effectiveness of up to 30-120dB in the 14KHz-40GHz frequency band.

[0029] The polyester fabric full-band electromagnetic shielding material of the present invention can be further produced into various shielding fabrics such as clothing through textile processing and other means. The material has good flexibility and is easy to secondary process. It can be widely used in many fields such as electronic equipment, military, modern weaponry, electric vehicles, and mobile communications. Attached Figure Description

[0030] Figure 1 The VSM magnetic susceptibility test curve for the sample in the test example;

[0031] Figure 2 The VSM coercivity test curve is shown for the sample in the test example. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0033] This invention provides a method for preparing a full-band electromagnetic shielding material made of polyester fabric, comprising the following steps:

[0034] (1) Pretreatment: Place the polyester fabric in the soaping solution, heat to 90-100℃, soap for 20-60 minutes, and then clean with ultrasonic waves.

[0035] The soaping solution includes 2 g / L sodium dodecyl sulfate and 2 g / L sodium hydroxide solution.

[0036] (2) Alkali treatment: Take 20-50 g / L sodium hydroxide solution and cationic surfactant, mix them, place the pretreated polyester fabric in it, control the temperature at 60-80℃, soak for 20-60 min, the alkali content can be reduced by 10-25% in this process;

[0037] Cationic surfactants such as trimethylammonium bromide containing 12-16 alkyl groups can be selected.

[0038] (3) Modification treatment: The polyester fabric is placed in the modification solution and soaked at room temperature for 8-20 minutes, then dried at 100-120℃, and then heated to 150-160℃ for 3-5 minutes to obtain the modified polyester fabric.

[0039] The modified liquid includes a modifier with a volume fraction of 1-5% and a penetrant with a volume fraction of 0.5-1%, with the remainder being water; the modifier is a mixture of nano-silver particles and mixed rare earth elements, and the penetrant is penetrant OP10.

[0040] During the modification process, the modifying liquid can react with the active groups on the surface of polyester fabric and form covalent bonds with metal, thereby greatly improving the bonding effectiveness between the metal and the polyester fabric.

[0041] (4) Activation treatment: The modified polyester fabric is placed in an ionic palladium solution, the pH value is adjusted to 10-11, and it is soaked at 30-50℃ for 10-60 min; after taking it out, it is ultrasonically cleaned, and then placed in a 0.5-2 g / L dimethylaminoborane solution for a reduction reaction for 10-30 min to obtain activated polyester fabric.

[0042] The palladium ion solution includes 0.05-0.5 g / L of PdCl2, 1-2 g / L of stabilizer (benzotriazole), 0.5 g / L of NH4Cl, and 0.5 g / L of ethylenediamine.

[0043] (5) Surface metallization: The activated polyester fabric is successively plated with copper with a thickness of 0.001-0.08 mm and soft magnetic alloy with a thickness of 0.001-0.05 mm to obtain metallized polyester fabric; among which, the soft magnetic alloy can be a nickel-based soft magnetic alloy.

[0044] Those skilled in the art can choose from methods such as vacuum plating, cold spraying, electroless plating, or electroplating to plate metals, depending on the specific circumstances. Taking electroless plating as an example, the operation for plating copper or soft magnetic alloys is as follows:

[0045] Place the activated polyester fabric or the copper-plated polyester fabric in the chemical plating solution and react at 20-100℃ for 10-60 minutes, with continuous shaking and stirring during the reaction.

[0046] The electroless copper plating solution includes: 10-18 g / L CuSO4·5H2O, 20-30 g / L EDTA-2Na, 5-20 mg / L stabilizer (using pyridine and thioimidazole compounds), 0.1-0.5 g / L PEG-6000, 5 g / L NaAc, and 8-18 ml / L formaldehyde. During copper plating, the pH of the electroless plating solution needs to be adjusted to 11.5-13, and the solution should be mixed thoroughly at a temperature of 40-60℃ for a reaction time of 20-80 minutes.

[0047] The electroless plating solution for nickel-based soft magnetic alloys includes: 7-15 g / L NiSO4·5H2O, 2-7 g / L Fe(NH4)2(SO4)2·6H2O, 1-5 g / L cobalt sulfate, 30-35 g / L potassium sodium tartrate, 10 g / L HBO3, 10-30 mg / L stabilizer (using pyridine and thioimidazole compounds as stabilizers), 0.1-0.5 g / L PEG-6000, and 1-5 g / L NaBH4. When plating the soft magnetic alloy, the pH of the electroless plating solution needs to be adjusted to 8.5-10, and the solution should be mixed thoroughly at a temperature of 55-70℃ for a reaction time of 20-80 minutes.

[0048] Based on polyester fabric substrate, metallized polyester fiber filaments are obtained through double-layer metallization technology, which have stronger electrical and magnetic conductivity and stronger metal adhesion. Compared with common silver-plated copper wire, the weight is reduced by 70-80%, and it has the advantages of light weight, high flexibility and high electromagnetic shielding performance.

[0049] (6) Processing and shaping: Metallized polyester fabrics coated with double-layer metal are processed into electromagnetic shielding materials of the required shape and size by cutting, bonding with conductive adhesive, welding and other methods.

[0050] The full-band electromagnetic shielding material of polyester fabric prepared by the technical means of this invention utilizes its excellent electrical and magnetic conductivity properties. The magnetic loss is composed of eddy current loss and hysteresis loss. Under the action of an external alternating electromagnetic field, the free electrons in the metal on the surface of the polyester fiber and the soft magnetic alloy film oscillate and generate oscillating current, which then converts the energy of the electromagnetic wave into heat energy and is thus dissipated. It can achieve an electromagnetic shielding effectiveness of up to 30-120dB in the 14KHz-40GHz frequency band.

[0051] The polyester fabric full-frequency electromagnetic shielding material of this invention can be applied to camouflage materials.

[0052] Those skilled in the art can mix polyester fabric full-band electromagnetic shielding material with other polyester materials to make camouflage nets, etc., according to actual needs. This can significantly improve the problem of poor low-frequency absorption performance of existing camouflage nets, achieve a higher degree of radar wave stealth effect, and also have the advantages of flame retardancy, durability, rainproof, and ease of use.

[0053] The polyester fabric full-band electromagnetic shielding material and its preparation method provided by the present invention can be further produced into various shielding fabrics such as clothing through textile processing and other means. The material has good flexibility and is easy to secondary process. It can be applied in many fields such as electronic equipment and electric vehicles. It has the advantages of good electromagnetic shielding effect, good material mechanical properties, and large size.

[0054] <Example>

[0055] Example 1

[0056] (1) Pretreatment: Place the polyester fabric in a mixture of equal volumes of 2 g / L sodium dodecyl sulfate and 2 g / L sodium hydroxide solution, heat to 95°C, soap for 40 min, and ultrasonically clean.

[0057] (2) Alkali treatment: Take 20 g / L sodium hydroxide solution and dodecyltrimethylammonium bromide, mix them, place the pretreated polyester fabric in the mixture, control the temperature at 70℃, and soak for 40 min.

[0058] (3) Modification treatment: The polyester fabric is placed in the modification solution and soaked at room temperature for 15 minutes, then dried at 110℃, and then heated to 155℃ for 3-5 minutes to obtain the modified polyester fabric.

[0059] The modified liquid includes a 3% by volume modifier (a mixture of nano-silver particles and mixed rare earth elements) and a 0.8% by volume penetrant, with the remainder being water.

[0060] (4) Activation treatment: The modified polyester fabric was placed in an ionic palladium solution, the pH was adjusted to 10.5, and it was soaked at 40℃ for 30 min. After taking it out, it was ultrasonically cleaned and then placed in a 1.5 g / L dimethylaminoborane solution for a reduction reaction for 20 min to obtain activated polyester fabric.

[0061] The palladium ion solution includes 0.25 g / L of PdCl2, 1.5 g / L of stabilizer, 0.5 g / L of NH4Cl, and 0.5 g / L of ethylenediamine.

[0062] (5) Surface metallization: 0.05 mm thick copper and 0.025 mm thick nickel-based soft magnetic alloy are successively plated on activated polyester fabric to obtain metallized polyester fabric.

[0063] (6) Processing and shaping: Metallized polyester fabrics coated with double-layer metal are processed into electromagnetic shielding materials of the required shape and size by cutting, bonding with conductive adhesive, welding and other methods.

[0064] Example 2

[0065] (1) Pretreatment: Place the polyester fabric in a mixture of equal volumes of 2 g / L sodium dodecyl sulfate and 2 g / L sodium hydroxide solution, heat to 95°C, soap for 60 min, and ultrasonically clean.

[0066] (2) Alkali treatment: Take 20 g / L sodium hydroxide solution and dodecyltrimethylammonium bromide, mix them, place the pretreated polyester fabric in the mixture, control the temperature at 60℃, and soak for 60 min.

[0067] (3) Modification treatment: The polyester fabric is placed in the modification solution and soaked at room temperature for 20 minutes. Then it is dried at 100℃ and then heated to 150℃ for 3-5 minutes to obtain the modified polyester fabric.

[0068] The modified liquid includes a modifier (a mixture of nano-silver particles and mixed rare earth elements) with a volume fraction of 1% and a penetrant with a volume fraction of 0.5%, with the remainder being water.

[0069] (4) Activation treatment: The modified polyester fabric was placed in an ionic palladium solution, the pH was adjusted to 10.5, and it was soaked at 30°C for 60 min. After taking it out, it was ultrasonically cleaned and then placed in a 0.5 g / L dimethylaminoborane solution for a reduction reaction for 30 min to obtain activated polyester fabric.

[0070] The palladium ion solution includes 0.05 g / L PdCl2, 1 g / L stabilizer, 0.5 g / L NH4Cl, and 0.5 g / L ethylenediamine.

[0071] (5) Surface metallization: 0.001 mm thick copper and 0.001 mm thick nickel-based soft magnetic alloy are successively plated on activated polyester fabric to obtain metallized polyester fabric.

[0072] (6) Processing and shaping: Metallized polyester fabrics coated with double-layer metal are processed into electromagnetic shielding materials of the required shape and size by cutting, bonding with conductive adhesive, welding and other methods.

[0073] Example 3

[0074] (1) Pretreatment: Place the polyester fabric in a mixture of equal volumes of 2 g / L sodium dodecyl sulfate and 2 g / L sodium hydroxide solution, heat to 100°C, soap for 20 min, and ultrasonically clean.

[0075] (2) Alkali treatment: Take 50 g / L sodium hydroxide solution and dodecyltrimethylammonium bromide, mix them, place the pretreated polyester fabric in the mixture, control the temperature at 80℃, and soak for 20 min.

[0076] (3) Modification treatment: The polyester fabric is placed in the modification solution and soaked at room temperature for 8 minutes. Then it is dried at 120℃ and then heated to 160℃ for 3 minutes to obtain the modified polyester fabric.

[0077] The modified liquid includes a 5% by volume modifier (a mixture of nano-silver particles and mixed rare earth elements) and a 1% by volume penetrant, with the remainder being water.

[0078] (4) Activation treatment: The modified polyester fabric is placed in an ionic palladium solution, the pH value is adjusted to 10.5, and it is soaked at 50℃ for 10 min; after taking it out, it is ultrasonically cleaned, and then placed in a 2 g / L dimethylaminoborane solution for reduction reaction for 10 min to obtain activated polyester fabric.

[0079] The palladium ion solution includes 0.5 g / L PdCl2, 2 g / L stabilizer, 0.5 g / L NH4Cl, and 0.5 g / L ethylenediamine.

[0080] (5) Surface metallization: 0.08 mm thick copper and 0.05 mm thick nickel-based soft magnetic alloy are successively plated on activated polyester fabric to obtain metallized polyester fabric.

[0081] (6) Processing and shaping: Metallized polyester fabrics coated with double-layer metal are processed into electromagnetic shielding materials of the required shape and size by cutting, bonding with conductive adhesive, welding and other methods.

[0082] Comparative Example 1

[0083] Polyester fabric is first ultrasonically cleaned, and then copper and nickel-based soft magnetic alloys are successively plated on its surface to obtain a polyester electromagnetic shielding material with a double layer of metal.

[0084] Test Example

[0085] Samples: Example 1, Comparative Example 1

[0086] The above samples, labeled A1 and A2 respectively, were used. The magnetic susceptibility and coercivity of the sample materials were measured using a vibrating sample magnetometer (VSM). The test results are as follows: Figures 1 to 2 As shown, Figure 1 The VSM susceptibility test curve for the sample (magnetic susceptibility unit: Dm / Dh) Figure 2 The figure shows the VSM coercivity test curve of the sample (coercivity unit: emu / g). As can be seen from the figure, the electromagnetic shielding material prepared by the technical means of this invention has significantly stronger magnetic permeability under the condition of comparable coercivity.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a full-band electromagnetic shielding material made of polyester fabric, characterized in that, Includes the following steps: S1 Pretreatment: Take polyester fabric, place it in soap boiling solution, heat and soap boiling, then wash; S2 Alkali Treatment: Place the soaped polyester fabric in a mixture of cationic surfactant and alkali, heat to 60-80℃, and soak for 20-60 minutes. S3 Modification Treatment: The polyester fabric is then placed in the modification solution, soaked for 8-20 minutes, dried, and then heated to 150-160℃ for heat treatment to obtain the modified polyester fabric. S4 Activation Treatment: The modified polyester fabric is placed in an ionic palladium solution, which includes PdCl2, a stabilizer, NH4Cl, and ethylenediamine, and Pd... 2+ The concentration of the active ingredient was 0.05-0.5 g / L, and the pH was adjusted to alkaline. The product was then soaked, washed, and then placed in a dimethylaminoborane solution for a reduction reaction to obtain activated polyester fabric. S5 Surface metallization: Copper plating and soft magnetic alloy plating are performed sequentially on the surface of activated polyester fabric. The thickness of the copper plating layer is controlled to be 0.001-0.08mm and the thickness of the soft magnetic alloy plating layer is controlled to be 0.001-0.05mm, so as to obtain metallized polyester fabric. S6 processes metallized polyester fabric into shape to obtain a full-band electromagnetic shielding material made of polyester fabric.

2. The method for preparing the full-band electromagnetic shielding material of polyester fabric according to claim 1, characterized in that, In step S1, the soaping solution includes sodium dodecyl sulfate and sodium hydroxide solution.

3. The method for preparing the full-band electromagnetic shielding material of polyester fabric according to claim 2, characterized in that, In step S1, the soap boiling temperature is controlled at 90-100℃.

4. The method for preparing the full-frequency electromagnetic shielding material of polyester fabric according to claim 1, characterized in that, In step S2, the cationic surfactant is selected from trimethylammonium bromide containing 12-16 alkyl groups.

5. A polyester fabric full-frequency electromagnetic shielding material prepared by the preparation method according to any one of claims 1 to 4.

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