Preparation method of flexible light-weight flame-retardant electromagnetic shielding cloth
By depositing nickel and copper layers on polymer cloth and adding flame retardants, a flexible and lightweight flame-retardant electromagnetic shielding cloth is prepared, which solves the problems of insufficient flexibility and flame retardancy of existing materials and achieves improved efficient electromagnetic shielding and fire protection performance.
Patent Information
- Application Number
- CN202510787780.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-09-12
AI Technical Summary
Existing electromagnetic shielding materials have poor flexibility and are heavy, making them difficult to process into shapes that meet actual application requirements. They also have insufficient flame retardancy and pose a fire safety hazard.
A nickel layer is deposited on a polymer cloth substrate using chemical nickel plating and electrolytic nickel plating processes, and a copper layer is formed by combining chemical copper plating and electrolytic copper plating. The copper layer is then mixed with a flame retardant to prepare a flexible and lightweight flame-retardant electromagnetic shielding cloth.
The prepared electromagnetic shielding cloth has excellent flexibility, lightness and B1 grade flame retardancy, and can effectively shield electromagnetic waves and provide protection in fire environments.
Smart Images
Figure CN120625366A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electromagnetic shielding, and in particular to a method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth. Background Art
[0002] With the rapid development of modern electronic technology, electromagnetic waves are increasingly used in military, industrial, and daily life. However, electromagnetic radiation also brings many hazards. For example, in the military field, with the widespread use of individual intelligent equipment, the electronic devices carried by soldiers have become potential sources of electromagnetic radiation. This radiation may not only cause damage to the soldiers' own health, but also expose combat positions and provide guidance information to the enemy, seriously affecting combat safety and effectiveness. In the civilian field, long-term exposure to electromagnetic radiation environments may also cause various health problems in the human body, such as nervous system disorders, cardiovascular diseases, and reproductive system abnormalities. Therefore, the development of effective electromagnetic radiation protection materials is of extremely important practical significance.
[0003] Current electronic shielding materials all have limitations. Metals, such as copper and aluminum, offer excellent electromagnetic shielding properties, based on the ability of free electrons within metals to reflect and absorb electromagnetic waves. However, metals have significant drawbacks. First, the high density of metals results in heavy metal-based electromagnetic shielding materials, a serious problem for protective equipment that needs to be worn or carried for extended periods, significantly impacting user comfort and flexibility. Second, metals lack flexibility and are difficult to process into ergonomic shapes, significantly limiting their practical applications. Conductive polymers, on the other hand, are a class of polymers with a certain degree of conductivity, such as polyaniline and polypyrrole. These materials offer excellent flexibility and processability, meeting certain flexibility requirements. However, compared to metals, their electromagnetic shielding properties are relatively weak, failing to provide sufficient shielding effectiveness and making them difficult to meet in some applications requiring high electromagnetic shielding requirements.
[0004] Composite materials have been developed to combine the advantages of metals and conductive polymers. These composite materials typically combine metal fibers or particles with a polymer matrix. While these materials offer some improvements in flexibility and electromagnetic shielding performance, they still present some challenges. For example, composite materials are still relatively heavy and often lack flame retardancy. In some specialized environments, such as fire-prone areas, lacking flame retardancy in electromagnetic shielding materials can lead to more serious safety incidents.
[0005] However, in modern society, both military equipment and civilian products place higher demands on material flexibility and lightweighting. For electromagnetic shielding materials, flexibility allows them to better adapt to different usage scenarios, such as wearable protective clothing and shielding covers for electronic devices; lightweighting improves user comfort and portability, reducing the burden of material weight. Furthermore, considering the various environments in which electromagnetic shielding materials may be used, flame retardancy becomes an important consideration. Especially in locations with high fire safety requirements, such as military bases, electronics factories, and public places, electromagnetic shielding materials with flame retardant properties can effectively prevent the spread of fire in the event of a fire, protecting the safety of personnel and equipment. Existing electromagnetic shielding materials cannot simultaneously meet the requirements of flexibility, lightweightness, and flame retardancy. Therefore, the development of a new type of flexible, lightweight, flame-retardant electromagnetic shielding fabric is of great practical significance and market demand. Summary of the Invention
[0006] The problem addressed by this invention is that current electromagnetic shielding materials, due to their inherent physical properties, are difficult to process into shapes that meet practical application requirements, resulting in poor flexibility and heavy weight. This impacts user comfort and portability, making them unsuitable for prolonged wear or carrying. Furthermore, existing electromagnetic shielding composite materials often exhibit poor flame retardancy, posing a safety hazard in fire-prone environments.
[0007] The present invention discloses a method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth, comprising the following steps:
[0008] (1) Colloidal palladium: Prepare palladium chloride (PdCl2) and stannous chloride (SnCl2) in a volume ratio of 1:1. Add a small amount of hydrochloric acid (HCl) solution at a temperature of 40-45°C and stir to form a colloidal solution. Place the pretreated polymer raw material cloth into the colloidal solution to allow a layer of colloidal palladium particles to be adsorbed on the surface of the substrate.
[0009] (2) Acid depolymerization: Add an appropriate amount of NaOH or H2SO4 solution to react and complex with the Sn²⁺ hydrolyzed gel layer adsorbed around the palladium particles to generate easily precipitated tin salts, exposing the palladium atoms and removing the protective micelles outside the colloidal palladium particles adsorbed on the surface during the activation treatment.
[0010] (3) Electroless nickel plating: Prepare an electroless nickel plating solution containing nickel sulfate (NiSO4), sodium citrate (Na3Cit), sodium hypophosphite (NaH2PO2), and ammonium chloride (NH4Cl) in a volume ratio of 1:1:1. Add ammonia (NH3H2O) to adjust the pH to 8.5-9.5. Place the acid-debonded raw cloth into the electroless nickel plating solution and store at 38°C.
[0011] (4) Chemical copper plating: The rolled raw cloth (nickel cloth in this case) is placed in a chemical copper plating solution. The copper ions undergo a reduction reaction on the surface of the nickel cloth and are deposited on the surface of the nickel cloth to form a copper layer.
[0012] (5) Electroplating copper: Prepare an electroplating copper solution with copper sulfate (CuSO4) as the main salt, and add sulfuric acid (H2SO4) to increase conductivity and improve coating crystallization, and add Cl - As an activator and brightener, opener, carrier, mover and wetting agent are added as brightener to improve the appearance of electroplating and enhance the performance of electroplating. Nickel cloth after chemical copper plating is used as cathode and phosphorus copper is used as anode. They are placed in the electroplating copper solution at 25℃. Under the action of the electric field, the copper ions in the plating solution are further deposited on the surface of the copper cloth to achieve a thicker copper layer and achieve ideal conductive properties.
[0013] (6) Nickel electroplating: Prepare a nickel electroplating solution with nickel sulfate (NiSO4) as the main salt, nickel chloride (NiCl2) as the anode activator, boric acid (H3BO3) as the buffer and appropriate additives. Place the copper-plated fabric as the cathode and nickel as the anode in the nickel electroplating solution with a pH of 3.5-4.5 at a temperature of 55±2℃ and a cathode current density of 2-10A / dm 2 Under the action of the electric field, nickel ions are deposited on the surface of the cloth to form a nickel layer, which serves as a protective layer to prevent the copper layer from oxidizing, and finally an electromagnetic shielding cloth is obtained.
[0014] (7) Proportioning ingredients: Accurately weigh various materials such as 20%-25% flame retardant, 65%-70% polymer material, 5%-10% functional additives, hot melt adhesive, etc. according to the formula. Place the materials into a mixing device and mix and stir at 30°C.
[0015] (8) Sizing: Use the roller to disperse the molten material to make the ingredients more uniform. Then use a scraper with an accuracy of 0.2 mm to scrape the ingredients onto the electromagnetic shielding cloth. Make sure the scraper scraping speed is uniform to ensure uniform sizing. After the scraping is completed, the fabric is rolled and packaged.
[0016] The flame retardant in step (7) is one or a combination of halogen flame retardants (including organic chlorides and organic bromides), phosphorus flame retardants (including inorganic phosphorus flame retardants such as red phosphorus and organic phosphorus flame retardants such as phosphates), nitrogen flame retardants and inorganic flame retardants (including antimony trioxide, magnesium hydroxide, aluminum hydroxide, etc.).
[0017] The polymer material used in step (7) is one or more composites of Oxford cloth, cotton cloth, nylon, cordura, polyester, non-woven fabric, modified rubber, polyurethane resin, stretch fabric, leather, flexible textiles, polyester film or a fiber composite of a radiation shielding composition, including PEEK resin that does not use lead.
[0018] The functional additives used in step (7) include one or more of a thickener, a plasticizer, an antistatic additive, an antibacterial additive, a leveling agent, and a light stabilizer.
[0019] The flexible, lightweight, flame-retardant electromagnetic shielding fabric produced by the method of the present invention can be used to protect housings or enclosures for electronic components or avionics equipment in high-temperature environments in aerospace equipment. This effectively addresses electromagnetic compatibility issues while improving aircraft fire resistance and ensuring flight safety. In the military sector, this flame-retardant electromagnetic shielding fabric can be used to manufacture military tents, protective clothing, and other items. It not only meets the electromagnetic shielding requirements of military equipment, preventing detection by enemy electromagnetic detection equipment, but also provides flame-retardant protection on the battlefield, reducing the risk of damage to military equipment and casualties caused by fire. The fabric not only shields all electromagnetic waves, exhibiting excellent shielding performance, but also boasts flame retardancy reaching Class B1. This flame retardancy effectively enhances the shielding fabric's fire resistance and greatly increases its safety. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 The present invention provides a production process for a flexible and lightweight flame-retardant electromagnetic shielding cloth.
[0021] Figure 2 This is a flame retardant performance test report of a flexible and lightweight flame retardant electromagnetic shielding cloth of the present invention.
[0022] Figure 3 This is the production flow chart for producing electromagnetic shielding cloth. DETAILED DESCRIPTION
[0023] Example 1
[0024] A method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth comprises the following steps:
[0025] (1) Colloidal palladium: Prepare palladium chloride (PdCl2) and stannous chloride (SnCl2) in a volume ratio of 1:1. Add a small amount of hydrochloric acid (HCl) solution at a temperature of 40-45°C and stir to form a colloidal solution. Place the pretreated polymer raw material cloth into the colloidal solution to allow a layer of colloidal palladium particles to be adsorbed on the surface of the substrate.
[0026] (2) Acid depolymerization: Add an appropriate amount of NaOH or H2SO4 solution to react and complex with the Sn²⁺ hydrolyzed gel layer adsorbed around the palladium particles to generate easily precipitated tin salts, exposing the palladium atoms and removing the protective micelles outside the colloidal palladium particles adsorbed on the surface during the activation treatment.
[0027] (3) Electroless nickel plating: Prepare an electroless nickel plating solution containing nickel sulfate (NiSO4), sodium citrate (Na3Cit), sodium hypophosphite (NaH2PO2), and ammonium chloride (NH4Cl) in a volume ratio of 1:1:1. Add ammonia (NH3H2O) to adjust the pH to 8.5-9.5. Place the acid-debonded raw cloth into the electroless nickel plating solution and store at 38°C.
[0028] (4) Chemical copper plating: The rolled raw cloth (nickel cloth in this case) is placed in a chemical copper plating solution. The copper ions undergo a reduction reaction on the surface of the nickel cloth and are deposited on the surface of the nickel cloth to form a copper layer.
[0029] (5) Electroplating copper: Prepare an electroplating copper solution with copper sulfate (CuSO4) as the main salt, and add sulfuric acid (H2SO4) to increase conductivity and improve coating crystallization, and add Cl - As an activator and brightener, opener, carrier, mover and wetting agent are added as brightener to improve the appearance of electroplating and enhance the performance of electroplating. Nickel cloth after chemical copper plating is used as cathode and phosphorus copper is used as anode. They are placed in the electroplating copper solution at 25℃. Under the action of the electric field, the copper ions in the plating solution are further deposited on the surface of the copper cloth to achieve a thicker copper layer and achieve ideal conductive properties.
[0030] (6) Nickel electroplating: Prepare a nickel electroplating solution with nickel sulfate (NiSO4) as the main salt, nickel chloride (NiCl2) as the anode activator, boric acid (H3BO3) as the buffer and appropriate additives. Place the copper-plated fabric as the cathode and nickel as the anode in the nickel electroplating solution with a pH of 3.5-4.5 at a temperature of 55±2℃ and a cathode current density of 2-10A / dm 2 Under the action of the electric field, nickel ions are deposited on the surface of the cloth to form a nickel layer, which serves as a protective layer to prevent the copper layer from oxidizing, and finally an electromagnetic shielding cloth is obtained.
[0031] (7) Proportioning ingredients: Accurately weigh 70% of polyurethane resin, 7% of zinc borate, and 23% of antimony trioxide, and place the weighed materials into a mixing device. Place the weighed materials into a mixing device and mix and stir at 30°C.
[0032] (8) Sizing: Use the roller to disperse the molten material to make the ingredients more uniform. Then use a scraper with an accuracy of 0.2 mm to scrape the ingredients onto the electromagnetic shielding cloth. Make sure the scraper scraping speed is uniform to ensure uniform sizing. After the scraping is completed, the fabric is rolled and packaged.
[0033] This embodiment provides a method for preparing a flexible, lightweight, flame-retardant electromagnetic shielding fabric. After obtaining a flexible, lightweight, and highly shielding electromagnetic shielding fabric, a mixture consisting of 70% polyurethane resin, 5% zinc borate, and 25% antimony trioxide is prepared. This mixture is melt-mixed and then knife-coated onto the prepared electromagnetic shielding fabric to produce an electromagnetic shielding fabric that meets the B1 flame retardancy standard. This embodiment ultimately produces an electromagnetic shielding fabric that is both flexible and lightweight, has excellent fully segmented shielding properties, and exhibits excellent flame retardancy.
[0034] Example 2
[0035] The difference between this embodiment and specific example 1 is that the flame retardant ratio in step (7) is a mixture of 68% polyurethane resin, 10% zinc borate and 22% antimony trioxide by mass.
[0036] Example 3
[0037] The difference between this embodiment and specific embodiment 1 or 2 is that the flame retardant ratio in step (7) is a mixture of 65% polyurethane resin, 10% zinc borate and 25% antimony trioxide by mass.
[0038] Example 4
[0039] The difference between this embodiment and specific examples 1, 2 or 3 is that the flame retardant ratio in step (7) is a mixture of 60% polyurethane resin, 5% zinc borate and 35% antimony trioxide by mass.
[0040] Example 5
[0041] The difference between this embodiment and specific examples 1, 2, 3 or 4 is that the flame retardant ratio in step (7) is a mixture of 80% polyurethane resin, 10% zinc borate and 10% antimony trioxide by mass.
[0042] Through the above preparation, it was found that the flexible and lightweight flame-retardant electromagnetic shielding cloth prepared by the flame retardant ratio in Example 1, Example 2 and Example 3, i.e., 65%-70% by mass of polyurethane resin, 5%-10% of zinc borate and 20%-25% of antimony trioxide, had the best flame retardant performance and could meet the B1 flame retardant standard.
Claims
1. A method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth, characterized by the following steps: (1) Colloidal palladium: palladium chloride (PdCl2) and stannous chloride (SnCl2) are prepared in a volume ratio of 1:1, and hydrochloric acid (HCl) solution is added at a temperature of 40-45°C and stirred to form a colloidal solution. The pretreated polymer raw material cloth is placed in the colloidal solution to allow a layer of colloidal palladium particles to be adsorbed on the surface of the substrate; (2) Acid debonding: Add NaOH or H2SO4 solution to make it react with Sn adsorbed around the palladium particles. 2+ The hydrolyzed gel layer reacts and complexes to generate tin salts that are easily precipitated, exposing palladium atoms and removing the protective micelles outside the colloidal palladium particles adsorbed on the surface during activation treatment; (3) Chemical nickel plating: Prepare a chemical nickel plating solution containing nickel sulfate (NiSO4), sodium citrate (Na3Cit), sodium hypophosphite (NaH2PO2), and ammonium chloride (NH4Cl) in a volume ratio of 1:1:
1. Add ammonia (NH3H2O) to adjust the pH to 8.5-9.
5. Place the acid-debonded raw cloth into the chemical nickel plating solution and store at 38°C. (4) Chemical copper plating: The rolled raw cloth is placed in a chemical copper plating solution. The copper ions undergo a reduction reaction on the surface of the nickel cloth and are deposited on the surface of the nickel cloth to form a copper layer. (5) Electroplating copper: Prepare an electroplating copper solution with copper sulfate (CuSO4) as the main salt, and add sulfuric acid (H2SO4) to increase conductivity and improve coating crystallization, and add Cl - As activator and brightener, opener, carrier, mover and wetting agent are added as brightener to improve the appearance of electroplating and enhance the performance of electroplating. Nickel cloth after chemical copper plating is used as cathode and phosphorus copper is used as anode. They are placed in electroplating copper solution at 25℃. Under the action of electric field, copper ions in the plating solution are further deposited on the surface of copper cloth to achieve thicker copper layer and ideal conductive performance. (6) Nickel electroplating: Prepare a nickel electroplating solution with nickel sulfate (NiSO4) as the main salt, nickel chloride (NiCl2) as the anode activator, boric acid (H3BO3) as the buffer and appropriate additives. Place the copper-plated fabric as the cathode and nickel as the anode in the nickel electroplating solution with a pH of 3.5-4.5 at a temperature of 55±2℃ and a cathode current density of 2-10A / dm 2 Under the action of the electric field, nickel ions are deposited on the surface of the cloth to form a nickel layer, which serves as a protective layer to prevent the copper layer from oxidizing, and finally an electromagnetic shielding cloth is obtained; (7) Ingredients: Place the materials into a mixing device with a mass fraction of 20%-25% flame retardant, 65%-70% polymer material, 5%-10% functional additive, and hot melt adhesive, and mix and stir at 30°C; (8) Sizing: Use the roller to disperse the molten material to make the ingredients more uniform. Then use a scraper with an accuracy of 0.2 mm to scrape the ingredients onto the electromagnetic shielding cloth. Make sure the scraping speed of the scraper is uniform to ensure uniform sizing. After the scraping is completed, the fabric is rolled up and packaged.
2. The method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth according to claim 1, characterized in that: The flame retardant is one or a combination of halogen flame retardants (including organic chlorides and organic bromides), phosphorus flame retardants (including inorganic phosphorus flame retardants such as red phosphorus and organic phosphorus flame retardants such as phosphates), nitrogen flame retardants and inorganic flame retardants (including zinc borate, antimony trioxide, magnesium hydroxide, aluminum hydroxide, etc.).
3. The method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth according to claim 1, characterized in that: The polymer material used is Oxford cloth, cotton cloth, nylon, Cordura, polyester, non-woven fabric, modified rubber, polyurethane resin, stretch fabric, leather, flexible textiles, polyester film or fiber composite of radiation shielding composition, etc., including one or more composites of PEEK resin that does not use lead.
4. The method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth according to claim 1, characterized in that: The functional additives used include one or more of a thickener, a plasticizer, an antistatic additive, an antibacterial additive, a leveling agent and a light stabilizer.
5. The method for preparing a flexible and lightweight flame-retardant electromagnetic shielding cloth according to claim 1, characterized in that: The preparation process of electromagnetic shielding cloth and flame retardant coating is a whole.