Production process of nano copper-aluminum alloy shielding tape

Abstract

The invention relates to the technical field of shielding tape preparation, and provides a nano-copper-aluminum alloy shielding tape which comprises a nano-copper-aluminum alloy core layer which is composed of copper, aluminum and a surface modifier, the atomic ratio of the copper to the aluminum is 6: 4-8: 2, and the surface modifier accounts for 0.5%-3% of the total mass of the alloy; the antioxidant coating layer coats the surface of the nano copper-aluminum alloy core layer, is composed of a polydopamine-silicon dioxide composite layer, and is 50-200 nm in thickness; according to the flexible polymer matrix, the nano copper-aluminum alloy core layer is evenly dispersed in the matrix, and the mass ratio of the matrix to the core layer is 95: 5-80: 20. The anti-oxidation coating layer of the nano copper-aluminum alloy shielding tape is formed by compounding polydopamine and silicon dioxide, oxygen and moisture permeation is doubly blocked, the oxidation resistance is improved, the service life is prolonged, thermoplastic polyurethane or silicone rubber is used as a matrix, dual guarantee is achieved with the coating layer, the exposure risk of nano particles is reduced, biocompatibility is considered, and living body and environment safety is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of shielded tape preparation, and specifically to a production process of a nano copper-aluminum alloy shielded tape. Background Art

[0002] In the field of electromagnetic shielding materials, traditional metal shielding materials such as copper tapes and aluminum tapes have certain shielding properties, but have disadvantages such as large weight, easy corrosion, and poor flexibility, making it difficult to meet the development needs of modern electronic devices for being thinner, lighter, and flexible. Nano copper-aluminum alloy has become a highly potential electromagnetic shielding material due to its advantages of good electrical conductivity and light weight.

[0003] However, there are many problems to be solved for nano copper-aluminum alloy. On the one hand, the surface activity of nano particles is high and they are easy to oxidize, resulting in a decrease in electrical conductivity and shielding performance. Moreover, the interaction force between nano particles is strong and they are easy to agglomerate, affecting the dispersion in the matrix and shielding uniformity. Existing surface coating modification technologies, such as graphene and silicone coatings, can improve the antioxidant property and dispersion to a certain extent, but the effect is limited, and the cost is high and the process is complex. On the other hand, when applied in fields with high requirements for biological safety such as biomedicine and wearable devices, nano particles may be released into the environment and organisms, causing potential toxicity hazards. The existing encapsulation technologies have poor biocompatibility and cannot effectively reduce the exposure risk of nano particles. In addition, the traditional production process of nano copper-aluminum alloy shielded tapes has deficiencies in controlling the alloy particle size, coating layer quality, and composite forming, resulting in unstable product performance and difficulty in large-scale industrial production. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention provides a production process of a nano copper-aluminum alloy shielded tape, which solves the problem of insufficient environmental stability of nano copper-aluminum alloy shielded tapes in the existing technology.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A nano copper-aluminum alloy shielded tape includes the following components and structures: Nano copper-aluminum alloy core layer: composed of copper, aluminum, and a surface modifier, the atomic ratio of copper to aluminum is 6:4 - 8:2, and the surface modifier accounts for 0.5% - 3% of the total mass of the alloy; Antioxidant coating layer: coated on the surface of the nano copper-aluminum alloy core layer, composed of a polydopamine-silica composite layer, with a thickness of 50 - 200 nm; Flexible polymer matrix: the nano copper-aluminum alloy core layer is uniformly dispersed in the matrix, and the mass ratio of the matrix to the core layer is 95:5 - 80:20.

[0006] Preferably, the surface modifier is selected from one of silane coupling agent KH-550 or graphene oxide.

[0007] Preferably, the matrix is one of thermoplastic polyurethane or silicone rubber.

[0008] Preferably, the particle size of the nano copper-aluminum alloy core layer is 20-100 nm, and the standard deviation of the particle size distribution ≤ 15 nm; in the polydopamine-silica composite layer, silica is embedded in the polydopamine network in the form of nanoparticles with a particle size of 10-30 nm.

[0009] Preferably, a production process of a nano copper-aluminum alloy shielding tape includes the following steps: S1. Preparation of nano copper-aluminum alloy powder: Weigh copper powder and aluminum powder according to the atomic ratio, add them into a ball milling tank, use argon as the protective atmosphere, the ball-to-material ratio is 10:1, the ball milling speed is 300-500 rpm, and the ball milling time is 10-20 h to obtain nano copper-aluminum pre-alloy powder; Immerse the pre-alloy powder into an ethanol solution containing a surface modifier, ultrasonically disperse it for 30-60 min, and then vacuum dry it at 60-80 °C for 6-12 h to obtain surface-modified nano copper-aluminum alloy powder; S2. Construction of the antioxidant coating layer: Place the powder prepared in step S1 into a dopamine-Tris buffer solution with pH = 8.5, stir and react for 12-24 h to coat polydopamine on the powder surface; Immerse the polydopamine-coated powder into an ethanol-ammonia aqueous solution of TEOS, the TEOS concentration is 0.1-0.5 mol / L, the reaction temperature is 25-40 °C, and the reaction time is 2-6 h to generate silica nanoparticles and embed them into the polydopamine layer; S3. Matrix compounding and forming: Mix the coated nano copper-aluminum alloy powder with the matrix, and melt-blend them at 180-220 °C through a twin-screw extruder, and the extrusion speed is 20-50 rpm to obtain composite masterbatch; Press the composite masterbatch into a shielding tape through a hot press, the hot pressing temperature is 180-200 °C, the pressure is 5-10 MPa, and the pressure holding time is 10-30 min. Finally, cool and shape it to obtain a shielding tape with a thickness of 0.1-0.5 mm.

[0010] Preferably, in S1, the ball milling process adopts a stepped speed increase method, with a low-speed ball milling at 300 rpm for the first 5 h and gradually increasing to 500 rpm in the subsequent 5-15 h.

[0011] Preferably, in S2, the volume ratio of the ethanol-ammonia aqueous solution is ethanol: water: ammonia = 80:15:5, and nitrogen is continuously introduced for protection during the reaction process.

[0012] Preferably, in S3, the length-diameter ratio of the twin-screw extruder is 40:1, and 0.1%-1% of zinc stearate is added as a dispersant during melt blending.

[0013] The present invention provides a production process for a nano copper-aluminum alloy shielding tape. It has the following beneficial effects: 1. The antioxidant coating layer of the nano copper-aluminum alloy shielding tape of the present invention is composed of a polydopamine-silica composite layer. Polydopamine is firmly coated on the surface of the alloy by chemical adsorption to provide a physical barrier. Silica nanoparticles are embedded in the polydopamine network to fill micropores and enhance denseness, double-blocking the penetration of oxygen and moisture, significantly improving the antioxidant performance of the shielding tape and extending its service life. The use of surface modifiers improves the dispersion of nano copper-aluminum alloy in the flexible polymer matrix, making the shielding performance more uniform and stable.

[0014] 2. The present invention uses thermoplastic polyurethane or silicone rubber as the flexible polymer matrix, which has good biocompatibility. The nano copper-aluminum alloy core layer is uniformly dispersed in the matrix, and the matrix tightly wraps the alloy particles to form a physical barrier. The polydopamine-silica composite layer first protects and modifies the surface of the alloy, and the matrix further encapsulates it at the macroscopic level, double-guaranteeing to reduce the exposure risk of nanoparticles, effectively reducing the exposure risk of nanoparticles during production, use, and waste treatment processes, and ensuring the safety of organisms and the environment.

[0015] 3. The present invention optimizes the ratio of ethanol-ammonia aqueous solution to provide a suitable hydrolysis environment, accelerates the formation of silica nanoparticles from TEOS, shortens the reaction time, and by strictly controlling the process steps and parameters, the cost per unit area of the shielding tape prepared by this solution is reduced by more than 30% compared with the traditional magnetron sputtering method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the nano copper-aluminum alloy shielding tape of the present invention; Figure 2 It is a process flow chart of the present invention.

[0017] Among them, 1. Flexible polymer matrix; 2. Nano copper-aluminum alloy core layer; 3. Antioxidant coating layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0019] Please refer to the attached Figure 1-2 , an embodiment of the present invention provides a nano copper-aluminum alloy shielding tape, including the following components and structures: Nano copper-aluminum alloy core layer 2: composed of copper, aluminum and a surface modifier, the atomic ratio of copper to aluminum is 6:4, and the surface modifier accounts for 2% of the total mass of the alloy; Antioxidant coating layer 3: coated on the surface of the nano copper-aluminum alloy core layer 2, composed of a polydopamine-silica composite layer, with a thickness of 100 nm; Flexible polymer matrix 1: The nano copper-aluminum alloy core layer 2 is uniformly dispersed in the matrix, and the mass ratio of the matrix to the core layer is 85:15.

[0020] A production process of a nano copper-aluminum alloy shielding tape includes the following steps: S1. Preparation of the nano copper-aluminum alloy core layer: Weigh copper powder and aluminum powder according to the atomic ratio of copper to aluminum of 6:4, add them to a ball milling tank, use argon as a protective atmosphere, set the ball-to-material ratio to 10:1, and adopt a stepped speed increase method during the ball milling process. For the first 5 hours, low-speed ball milling is carried out at 300 rpm, which can preliminarily mix the copper powder and aluminum powder evenly and avoid excessive particle collision and agglomeration caused by high-speed ball milling. In the next 10 hours, the speed is gradually increased to 500 rpm to further refine and alloy the particles, and finally obtain nano copper-aluminum pre-alloy powder; Immerse the pre-alloy powder in an ethanol solution containing silane coupling agent KH-550, and perform ultrasonic dispersion for 45 minutes. Ultrasonic dispersion can make the silane coupling agent KH-550 fully contact with the pre-alloy powder. Subsequently, vacuum dry at 70°C for 8 hours to obtain surface-modified nano copper-aluminum alloy powder. The amino group in the silane coupling agent KH-550 molecule can form a chemical bond with the metal atoms on the surface of the nano copper-aluminum alloy, and the ethoxy group can react with the groups in the subsequent matrix material after hydrolysis, thereby establishing a bridge between the nano copper-aluminum alloy and the matrix, enhancing the interaction between the two, and being conducive to improving the dispersion of the nano copper-aluminum alloy in the matrix; S2. Construction of the antioxidant coating layer: Place the prepared surface-modified nano copper-aluminum alloy powder in a dopamine-Tris buffer solution with a pH of 8.5, stir and react for 18 hours to coat the powder with polydopamine. Polydopamine has good adhesion and can tightly coat the surface of the nano copper-aluminum alloy powder to form a dense protective film, effectively preventing oxidizing substances such as oxygen from contacting the nano copper-aluminum alloy, thereby inhibiting the occurrence of oxidation reactions; Subsequently, the polydopamine-coated powder was immersed in an ethanol-ammonia aqueous solution with a TEOS concentration of 0.3 mol / L, where the volume ratio of ethanol, water, and ammonia water was 80:15:5. The reaction temperature was controlled at 30 °C, and the reaction time was 4 hours. Nitrogen was continuously introduced during the reaction for protection, which was beneficial for TEOS to hydrolyze to form silicon dioxide nanoparticles and embed in the polydopamine layer. Silicon dioxide itself has stable chemical properties and good antioxidant performance, and can cooperate with polydopamine to jointly improve the antioxidant ability of the nano copper-aluminum alloy; S3. Matrix compounding and molding: Thermoplastic polyurethane was selected as the matrix. The coated nano copper-aluminum alloy powder and the matrix were mixed at a mass ratio of 85:15, and melt-blended at 200 °C through a twin-screw extruder with a length-diameter ratio of 40:1. The extrusion speed was 30 rpm. 0.5% zinc stearate was added as a dispersant during melt-blending. Zinc stearate can reduce the friction and surface tension between materials and further improve the dispersion of the powder in the matrix; After obtaining the composite masterbatch, it was pressed into a shielding tape by a hot press. The hot pressing temperature was 190 °C, the pressure was 8 MPa, and the pressure holding time was 20 minutes. Finally, it was cooled and shaped to obtain a shielding tape with a thickness of 0.3 mm. Example

[0021] This example provides a nano copper-aluminum alloy shielding tape, including the following components and structures: Nano copper-aluminum alloy core layer 2: Composed of copper, aluminum, and a surface modifier, the atomic ratio of copper to aluminum is 7:3, and the surface modifier accounts for 2% of the total mass of the alloy; Antioxidant coating layer 3: Coated on the surface of the nano copper-aluminum alloy core layer 2, composed of a polydopamine-silicon dioxide composite layer, with a thickness of 150 nm; Flexible polymer matrix 1: The nano copper-aluminum alloy core layer 2 is uniformly dispersed in the matrix, and the mass ratio of the matrix to the core layer is 90:10.

[0022] A production process of a nano copper-aluminum alloy shielding tape includes the following steps: S1. Preparation of the nano copper-aluminum alloy core layer: Weigh copper powder and aluminum powder so that the atomic ratio of copper to aluminum is 7:3, add them to a ball milling tank, and under argon protection, with a ball-to-material ratio of 10:1. First, ball mill at a low speed of 300 rpm for 5 hours, and then gradually increase to 500 rpm and continue ball milling for 12 hours to obtain nano copper-aluminum pre-alloy powder; Put the pre-alloyed powder into an ethanol solution containing graphene oxide, and ultrasonically disperse it for 50 minutes. Then, vacuum dry it at 75 °C for 10 hours to obtain surface-modified nano copper-aluminum alloy powder. Graphene oxide has a large specific surface area and abundant functional groups, which can adsorb on the surface of the nano copper-aluminum alloy, increase the steric hindrance between particles, reduce the agglomeration between particles, and improve the dispersibility; S2. Construction of antioxidant coating layer: Put the surface-modified nano copper-aluminum alloy powder into a dopamine-Tris buffer solution with a pH of 8.5, and stir and react for 20 hours to coat the surface of the powder with polydopamine; Then immerse it in an ethanol-ammonia aqueous solution (ethanol: water: ammonia = 80:15:5) with a TEOS concentration of 0.4 mol / L, and react at 35 °C for 5 hours. During the reaction, continuously pass nitrogen for protection. The composite layer formed by polydopamine and silica nanoparticles can effectively improve the antioxidant performance of the nano copper-aluminum alloy.

[0023] S3. Matrix composite and molding: Using silicone rubber as the matrix, mix the coated nano copper-aluminum alloy powder and the matrix at a mass ratio of 90:10, and melt-blend them at 210 °C through a twin-screw extruder with a length-diameter ratio of 40:1. The extrusion speed is 40 rpm, and 0.8% zinc stearate is added as a dispersant. Then, through a hot press molding machine, keep the pressure at 9 MPa at 195 °C for 25 minutes, and cool and shape to obtain a shielding tape with a thickness of 0.4 mm. Example

[0024] This example provides a nano copper-aluminum alloy shielding tape, including the following components and structures: Nano copper-aluminum alloy core layer 2: Composed of copper, aluminum and a surface modifier, the atomic ratio of copper to aluminum is 8:2, and the surface modifier accounts for 2% of the total mass of the alloy; Antioxidant coating layer 3: Coated on the surface of the nano copper-aluminum alloy core layer 2, composed of a polydopamine-silica composite layer, with a thickness of 150 nm; Flexible polymer matrix 1: The nano copper-aluminum alloy core layer 2 is uniformly dispersed in the matrix, and the mass ratio of the matrix to the core layer is 95:5.

[0025] A production process of a nano copper-aluminum alloy shielding tape includes the following steps: S1. Preparation of nano copper-aluminum alloy core layer: Weigh copper powder and aluminum powder according to the atomic ratio of copper to aluminum of 8:2 and add them to the ball mill tank. Protect with argon, the ball-to-material ratio is 10:1. During ball milling, first ball mill at a low speed of 300 rpm for 5 hours, and then gradually increase to 500 rpm in the next 15 hours to obtain nano copper-aluminum pre-alloyed powder; The pre-alloyed powder was immersed in an ethanol solution containing silane coupling agent KH-550, ultrasonically dispersed for 30 minutes, and vacuum dried at 60 °C for 12 hours to obtain surface-modified nano copper-aluminum alloy powder. The silane coupling agent KH-550 improved the bonding force between the nano copper-aluminum alloy and the matrix and enhanced the dispersibility; S2. Construction of antioxidant coating layer: The powder was placed in a dopamine-Tris buffer solution with pH = 8.5 and stirred for reaction for 12 hours to be coated with polydopamine; Then it was immersed in an ethanol-ammonia aqueous solution (ethanol: water: ammonia = 80:15:5) with TEOS concentration of 0.1 mol / L and reacted at 25 °C for 6 hours under nitrogen protection. The polydopamine-silica composite layer provided antioxidant protection for the nano copper-aluminum alloy; S3. Matrix composite and molding: Using thermoplastic polyurethane as the matrix, the coated nano copper-aluminum alloy powder and the matrix were mixed at a mass ratio of 95:5, melt-blended at 180 °C through a twin-screw extruder with a length-diameter ratio of 40:1, the extrusion speed was 20 rpm, and 0.1% zinc stearate was added as a dispersant. It was hot-pressed and molded at 180 °C and a pressure of 5 MPa for 30 minutes of pressure holding, and then cooled and shaped to obtain a shielding tape with a thickness of 0.1 mm.

[0026] Comparative example: To compare the performance advantages of the nano copper-aluminum alloy shielding tape of the present invention, the following comparative example was designed to prepare an ordinary nano copper-aluminum alloy shielding tape without surface modification and antioxidant coating treatment, specifically as follows: Nano copper-aluminum alloy core layer: Copper powder and aluminum powder were weighed according to the atomic ratio of copper to aluminum of 6:4, added to a ball milling tank, with argon as the protective atmosphere, the ball-to-material ratio of 10:1, the ball milling speed of 400 rpm, and the ball milling time of 15 h to obtain nano copper-aluminum pre-alloyed powder, which was directly used as the nano copper-aluminum alloy core layer. Flexible polymer matrix: Thermoplastic polyurethane was selected as the matrix, the nano copper-aluminum alloy core layer and the matrix were mixed at a mass ratio of 85:15, melt-blended at 200 °C through a twin-screw extruder, the extrusion speed was 30 rpm, and no zinc stearate dispersant was added. After obtaining the composite masterbatch, it was hot-pressed into a shielding tape by a hot press molding machine, the hot pressing temperature was 190 °C, the pressure was 8 MPa, and the pressure holding time was 20 minutes. Finally, it was cooled and shaped to obtain a shielding tape with a thickness of 0.3 mm.

[0027] The performance test results of the shielding tapes prepared in the above examples and comparative examples are shown in the following table: In summary, the nano copper-aluminum alloy shielding tape of the present invention exhibits obvious advantages in aspects such as antioxidant performance, control of the risk of nanoparticle release, shielding performance, and mechanical properties, and has higher practical value and application prospects.

[0028] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A nano copper-aluminum alloy shielding tape, characterized in that, It includes the following components and structures: Nano copper-aluminum alloy core layer (2): It is composed of copper, aluminum and a surface modifier. The atomic ratio of copper to aluminum is 6:4 - 8:2, and the surface modifier accounts for 0.5% - 3% of the total mass of the alloy; Antioxidant coating layer (3): Coated on the surface of the nano copper-aluminum alloy core layer (2), composed of a polydopamine-silica composite layer, with a thickness of 50 - 200 nm; Flexible polymer matrix (1): The nano copper-aluminum alloy core layer (2) is uniformly dispersed in the matrix, and the mass ratio of the matrix to the core layer is 95:5 - 80:

20.

2. The nano copper-aluminum alloy shielding tape according to claim 1, characterized in that, The surface modifier is selected from one of silane coupling agent KH-550 or graphene oxide.

3. The nano copper-aluminum alloy shielding tape according to claim 1, characterized in that The matrix is one of thermoplastic polyurethane or silicone rubber.

4. A nano copper-aluminum alloy shielding tape according to claim 1, characterized in that, The particle size of the nano copper-aluminum alloy core layer is 20 - 100 nm, and the standard deviation of the particle size distribution ≤ 15 nm; in the polydopamine-silica composite layer, silica is embedded in the polydopamine network in the form of nanoparticles, with a particle size of 10 - 30 nm.

5. A production process of a nano copper-aluminum alloy shielding tape, using a nano copper-aluminum alloy shielding tape as described in any one of claims 1-4, characterized in that, It includes the following steps: S1. Preparation of nano copper-aluminum alloy powder: Weigh copper powder and aluminum powder according to the atomic ratio, add them into a ball milling tank, use argon as the protective atmosphere, the ball-to-powder ratio is 10:1, the ball milling speed is 300 - 500 rpm, and the ball milling time is 10 - 20 h to obtain nano copper-aluminum pre-alloy powder; Immerse the pre-alloy powder into an ethanol solution containing a surface modifier, ultrasonically disperse it for 30 - 60 min, and then vacuum dry it at 60 - 80°C for 6 - 12 h to obtain surface-modified nano copper-aluminum alloy powder; S2. Construction of the antioxidant coating layer: Place the powder prepared in step S1 into a dopamine-Tris buffer solution with pH = 8.5, stir and react for 12 - 24 h to coat the powder surface with polydopamine; Immerse the polydopamine-coated powder into an ethanol-ammonia aqueous solution of TEOS, with the TEOS concentration of 0.1 - 0.5 mol / L, the reaction temperature of 25 - 40°C, and the reaction time of 2 - 6 h to generate silica nanoparticles and embed them into the polydopamine layer; S3. Matrix compounding and molding: Mix the coated nano copper-aluminum alloy powder with the matrix, and melt-blend them through a twin-screw extruder at 180 - 220°C, with an extrusion speed of 20 - 50 rpm to obtain composite masterbatch; Press the composite masterbatch into a shielding tape through a hot press molding machine, with a hot press temperature of 180 - 200°C, a pressure of 5 - 10 MPa, and a holding pressure time of 10 - 30 min, and finally cool and shape it to obtain a shielding tape with a thickness of 0.1 - 0.5 mm.

6. The production process of a nano copper-aluminum alloy shielding tape according to claim 5, characterized in that, In step S1, the ball milling process adopts a stepped speed increase method. The first 5 h is ball milled at a low speed of 300 rpm, and the speed is gradually increased to 500 rpm in the subsequent 5 - 15 h.

7. The production process of a nano copper-aluminum alloy shielding tape according to claim 5, characterized in that, In step S2, the volume ratio of the ethanol-ammonia aqueous solution is ethanol:water:ammonia = 80:15:5, and nitrogen is continuously introduced for protection during the reaction process.

8. The production process of a nano copper-aluminum alloy shielding tape according to claim 5, characterized in that, In step S3, the length-diameter ratio of the twin-screw extruder is 40:1, and 0.1% - 1% of zinc stearate is added as a dispersant during melt-blending.

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