An ultrathin flexible electronic conductor material and its preparation method

Abstract

This application relates to the field of flexible electronics technology, specifically to an ultrathin flexible electronic conductor material and its preparation method. The preparation method of the ultrathin flexible electronic conductor material is as follows: (1) adding conductive filler, dispersant and binder to deionized water, ultrasonically dispersing to obtain a conductive slurry, coating the conductive slurry on the surface of a flexible substrate layer, and drying and curing to obtain a flexible substrate layer with a conductive functional layer; (2) preparing a polyethylene terephthalate solution, coating the polyethylene terephthalate solution on the surface of the conductive functional layer, and curing to obtain the ultrathin flexible electronic conductor material. This ultrathin flexible electronic conductor material has low sheet resistance, high conductivity stability, excellent bending resistance and solvent resistance, and significantly improved tensile strength and elongation at break, exhibiting excellent mechanical properties, making it suitable for long-term reliable application of flexible electronic devices.

Description

Technical Field

[0001] This application relates to the field of flexible electronics technology, and more specifically, to an ultrathin flexible electronic conductor material and its preparation method. Background Technology

[0002] With the rapid development of flexible electronics technology, fields such as foldable displays, smart wearable devices, flexible sensors, and medical bioelectronics have experienced explosive growth. This has placed stringent requirements on core electronic conductor materials, demanding ultra-thinness, high flexibility, high conductivity, and good stability. Currently, traditional conductor materials are unable to simultaneously meet these comprehensive performance requirements, which has become a key bottleneck restricting the upgrading of flexible electronic devices towards lightweight, miniaturized, and wearable designs.

[0003] Currently, the conductor materials widely used in flexible electronics mainly include indium tin oxide (ITO) films, metal nanowire films, conductive polymers, and carbon-based materials. While ITO films possess excellent optoelectronic properties, they are brittle and lack flexibility, easily cracking and failing under bending and folding deformations. Furthermore, the scarcity of indium resources leads to high costs, and the high-temperature fabrication process has poor compatibility with flexible substrates, making it difficult to meet the demands of ultra-thin flexible devices. Metal nanowire films (such as silver nanowires) improve flexibility, but suffer from weak interfacial bonding, easy oxidation, high surface roughness, and high contact resistance, leading to performance degradation over long-term use. Their complex fabrication process also hinders large-area uniform coating and mass production. Conductive polymer materials offer excellent flexibility but have low conductivity and poor environmental stability, failing to meet high conductivity requirements. Carbon-based materials (such as graphene and carbon nanotubes) combine flexibility and conductivity, but the high cost of producing high-quality films and the difficulty in large-scale production, along with the need to improve their compatibility with flexible substrates, make them less suitable for high-conductivity applications.

[0004] Therefore, developing a flexible electronic conductor material that combines ultra-thin structure, high flexibility, high conductivity, good environmental stability, simple preparation process, controllable cost, and suitability for large-scale production, in order to solve the performance and process bottlenecks of existing materials and adapt to the diversified application needs of flexible electronic devices, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the technical problems mentioned in the background section, this application provides an ultrathin flexible electronic conductor material and its preparation method.

[0006] This application provides a method for preparing an ultrathin flexible electronic conductor material, employing the following technical solution:

[0007] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0008] Step (1): Add conductive filler, dispersant and binder to deionized water, disperse by ultrasonication to obtain conductive slurry, coat the conductive slurry on the surface of flexible substrate, dry and cure to form conductive functional layer, and obtain flexible substrate with conductive functional layer.

[0009] Step (2): Polyethylene terephthalate and hexafluoroisopropanol are mixed and stirred evenly at a temperature of 60-80℃ to obtain a polyethylene terephthalate solution; the polyethylene terephthalate solution is coated on the surface of the conductive functional layer and cured to form a protective layer, thus obtaining an ultra-thin flexible electronic conductor material with a protective layer.

[0010] Preferably, in step (1), the mass ratio of the conductive filler, dispersant, binder and deionized water is 60-85: 5-15: 10-25: 200-300.

[0011] Preferably, in step (1), the conductive filler is selected from one or more of silver nanowires, graphene, and reduced graphene oxide; the dispersant is selected from one or more of sodium dodecylbenzenesulfonate, polyethylene glycol, and polyvinylpyrrolidone; and the binder is selected from one or more of waterborne polyurethane, polyimide, and epoxy resin.

[0012] Preferably, in step (2), the curing process specifically involves pre-curing at 100-110℃ for 1.5-2.5 hours, followed by heating to 120-130℃ for 2-3 hours of constant temperature curing.

[0013] Preferably, in step (1), the method for preparing the flexible substrate layer includes the following steps:

[0014] Step 1: Under the protection of an inert gas at a temperature of 25-30℃, add the diamine monomer to N,N-dimethylacetamide and stir until homogeneous. Then add the dianhydride monomer in 5 batches, stirring for 15-20 minutes after each batch is added. After all the monomers are added, continue stirring for 2-3 hours to obtain the prepolymer.

[0015] Step 2: Add polyethersulfone, polyetheretherketone and silane-modified nano silica to the prepolymer, disperse by ultrasonication, add triethylamine and hydroquinone, heat to 40-45℃, stir at constant temperature for 1-3 hours to obtain flexible base liquid.

[0016] Step 3: The flexible base liquid is cast onto a glass substrate using a casting machine. The cast film, along with the glass substrate, is placed in an oven for gradient heating imidization. After cooling to room temperature, the film is peeled off from the glass substrate to obtain the flexible base layer.

[0017] Preferably, in step 1, the mass ratio of N,N-dimethylacetamide, diamine monomer, and dianhydride monomer is 100-120:8-15:10-20.

[0018] Preferably, in step 1, the diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 10-12:5-8; and the dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0019] Preferably, in step 2, the mass ratio of the prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5-12:3-8:2-5:1-3:0.5-1.

[0020] Preferably, in step 3, the specific heating program for the gradient heating imidization is as follows: after holding at 80-90℃ for 1-2 hours, the temperature is increased to 150-160℃ at a heating rate of 3-5℃ / min, held for 1-2 hours, then increased to 250-280℃ at a heating rate of 3-5℃ / min, held for 1-2 hours, and finally increased to 300-320℃ at a heating rate of 1-2℃ / min, held for 30-40 minutes.

[0021] An ultrathin flexible electronic conductor material is prepared by the above-described preparation method.

[0022] Preferably, the thickness of the flexible substrate layer is 5-12 μm; the thickness of the conductive functional layer is 200-500 nm; and the thickness of the protective layer is 2-5 μm.

[0023] In summary, this application has the following beneficial effects:

[0024] This application optimizes the fabrication process parameters of the flexible substrate, precisely controls the raw material ratio and component selection, and enables the prepared ultrathin flexible electronic conductor material to possess excellent flexibility, conductivity and stability. It solves the technical problems of insufficient flexibility, easy breakage and unstable conductivity of traditional flexible conductor materials, and is suitable for the application needs of ultrathin flexible electronic devices.

[0025] This application utilizes a specific ratio of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone to form a diamine monomer during the preparation of a flexible substrate. This monomer is then polymerized with 3,3',4,4'-benzophenone tetracarboxylic dianhydride, resulting in a prepolymer with excellent film-forming properties and flexibility. Compared to flexible substrates prepared from a single diamine monomer, this effectively improves the bending resistance and mechanical strength of the conductor material, avoiding the problems of easy cracking and detachment of the substrate.

[0026] This application combines the advantages of each component by adding polyethersulfone, polyetheretherketone, and silane-modified nano-silica to a flexible base liquid. Polyethersulfone and polyetheretherketone can synergistically improve the toughness and high temperature resistance of the base layer, while silane-modified nano-silica can enhance the wear resistance and stability of the base layer. This results in a flexible base layer that combines excellent flexibility, high temperature resistance, and mechanical properties, making it suitable for different application scenarios.

[0027] This application optimizes the curing process of the flexible substrate by gradually increasing the curing temperature and controlling the holding time through a gradient heating method. This allows the solvent in the flexible substrate liquid to fully evaporate, resulting in tighter cross-linking of molecular chains. Consequently, the flexible substrate exhibits better dimensional stability and is less prone to shrinkage and deformation. At the same time, it improves the mechanical properties and chemical resistance of the flexible substrate, ensuring the long-term stable use of the entire conductor material. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments.

[0029] This application provides a method for preparing an ultrathin flexible electronic conductor material, comprising the following preparation steps:

[0030] Step (1): Add conductive filler, dispersant and binder to deionized water, disperse by ultrasonication to obtain conductive slurry, coat the conductive slurry on the surface of flexible substrate, dry and cure to form conductive functional layer, and obtain flexible substrate with conductive functional layer.

[0031] Step (2): Polyethylene terephthalate and hexafluoroisopropanol are mixed and stirred evenly at a temperature of 60-80℃ to obtain a polyethylene terephthalate solution; the polyethylene terephthalate solution is coated on the surface of the conductive functional layer and cured to form a protective layer, thus obtaining an ultra-thin flexible electronic conductor material with a protective layer.

[0032] In step (1), the mass ratio of the conductive filler, dispersant, binder and deionized water is 60-85: 5-15: 10-25: 200-300.

[0033] In step (1), the conductive filler is selected from one or more of silver nanowires, graphene, and reduced graphene oxide; the dispersant is selected from one or more of sodium dodecylbenzenesulfonate, polyethylene glycol, and polyvinylpyrrolidone; and the binder is selected from one or more of waterborne polyurethane, polyimide, and epoxy resin.

[0034] In step (2), the curing process specifically involves pre-curing at 100-110℃ for 1.5-2.5 hours, followed by heating to 120-130℃ for 2-3 hours of constant temperature curing.

[0035] In step (1), the method for preparing the flexible substrate layer includes the following steps:

[0036] Step 1: Under the protection of an inert gas at a temperature of 25-30℃, add the diamine monomer to N,N-dimethylacetamide and stir until homogeneous. Then add the dianhydride monomer in 5 batches, stirring for 15-20 minutes after each batch is added. After all the monomers are added, continue stirring for 2-3 hours to obtain the prepolymer.

[0037] Step 2: Add polyethersulfone, polyetheretherketone and silane-modified nano silica to the prepolymer, disperse by ultrasonication, add triethylamine and hydroquinone, heat to 40-45℃, stir at constant temperature for 1-3 hours to obtain flexible base liquid.

[0038] Step 3: The flexible base liquid is cast onto a glass substrate using a casting machine. The cast film, along with the glass substrate, is placed in an oven for gradient heating imidization. After cooling to room temperature, the film is peeled off from the glass substrate to obtain the flexible base layer.

[0039] In step 1, the mass ratio of N,N-dimethylacetamide, diamine monomer, and dianhydride monomer is 100-120:8-15:10-20.

[0040] In step 1, the diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 10-12:5-8; the dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0041] Preferably, in step 2, the mass ratio of the prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5-12:3-8:2-5:1-3:0.5-1.

[0042] In step 3, the specific heating program for the gradient heating imidization is as follows: after holding at 80-90℃ for 1-2 hours, the temperature is increased to 150-160℃ at a heating rate of 3-5℃ / min, and held for 1-2 hours; then the temperature is increased to 250-280℃ at a heating rate of 3-5℃ / min, and held for 1-2 hours; finally, the temperature is increased to 300-320℃ at a heating rate of 1-2℃ / min, and held for 30-40 minutes.

[0043] An ultrathin flexible electronic conductor material is prepared by the above-described preparation method.

[0044] The thickness of the flexible substrate layer is 5-12 μm; the thickness of the conductive functional layer is 200-500 nm; and the thickness of the protective layer is 2-5 μm.

[0045] The polyethylene terephthalate (brand name: RE5329) used in the examples and comparative examples of this application was purchased from Dongguan Xinshengli Plastic New Material Technology Co., Ltd.; 1,3-bis(4'-aminophenoxy)benzene was purchased from Wuhan Kanos Technology Co., Ltd.; 4,4'-bis(4-aminophenoxy)benzophenone was purchased from Wuhan Haorong Biotechnology Co., Ltd.; 3,3',4,4'-benzophenone tetracarboxylic dianhydride was purchased from Wuhan Lingfan Technology Co., Ltd.; polyethersulfone was purchased from Shanghai Liangrun International Trade Co., Ltd.; polyetheretherketone was purchased from Changzhou Wanhui New Material Technology Co., Ltd.; silane-modified nano-silica (particle size: 15nm) was purchased from Hangzhou Jiuli Biomaterials Co., Ltd.; graphene was purchased from Jinan Yuanhai Chemical Co., Ltd.; and waterborne polyurethane was purchased from Shanghai Bolino New Material Technology Co., Ltd.

[0046] Examples 1-3 provide an ultrathin flexible electronic conductor material and its preparation method.

[0047] Example 1

[0048] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0049] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 30 min with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 0.5 m / min and dried at 60 °C for 8 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 60:5:10:200. The thickness of the flexible substrate was 5 μm and the thickness of the conductive functional layer was 200 nm.

[0050] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:5. The mixture is stirred at 60°C for 20 minutes at a stirring speed of 300 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 1 m / min. The layer is pre-cured at 100°C for 1.5 h, and then heated to 120°C for 2 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 2 μm.

[0051] The method for preparing the flexible substrate layer includes the following steps:

[0052] Step 1: Under nitrogen protection at 25℃, add diamine monomer to N,N-dimethylacetamide and stir at 200 rpm for 30 min. After stirring evenly, add dianhydride monomer in 5 batches, each batch being 20% ​​of the total mass of dianhydride monomer. Stir for 15 min after each batch is added. After all the monomers are added, continue stirring for 2 h to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer and dianhydride monomer is 100:8:10. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 10:5. The dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0053] Step 2: Add polyethersulfone, polyetheretherketone, and silane-modified nano-silica to the prepolymer. After ultrasonic dispersion for 20 min at an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz, add triethylamine and hydroquinone. Heat to 40 °C and stir at a constant temperature of 300 rpm for 1 h to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5:3:2:1:0.5.

[0054] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 40°C and a casting rate of 0.5 m / min. Place the cast film along with the glass substrate into an oven and heat it at 80°C for 1 hour. Then, heat it to 150°C at a rate of 3°C / min and heat it for 1 hour. Next, heat it to 250°C at a rate of 3°C / min and heat it for 1 hour. Finally, heat it to 300°C at a rate of 1°C / min and heat it for 30 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0055] Example 2

[0056] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0057] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 45 min with an ultrasonic power of 250 W and an ultrasonic frequency of 50 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 1 m / min and dried at 70 °C for 9 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 75:10:18:250. The thickness of the flexible substrate was 8 μm and the thickness of the conductive functional layer was 350 nm.

[0058] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:8. The mixture is stirred at 70°C for 25 minutes at a stirring speed of 400 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 2 m / min. The layer is pre-cured at 110°C for 2 hours and then heated to 125°C for 2.5 hours to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 3.5 μm.

[0059] The method for preparing the flexible substrate layer includes the following steps:

[0060] Step 1: Under nitrogen protection at 28℃, add diamine monomer to N,N-dimethylacetamide and stir at 300 rpm for 35 min. After stirring evenly, add dianhydride monomer in 5 batches, each batch being 20% ​​of the total mass of dianhydride monomer. Stir for 18 min after each batch is added. After all the monomers are added, continue stirring for 2.5 h to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer and dianhydride monomer is 110:12:15. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 11:7. The dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0061] Step 2: Add polyethersulfone, polyetheretherketone, and silane-modified nano-silica to the prepolymer. After ultrasonic dispersion at a power of 250W and a frequency of 50kHz for 30 minutes, add triethylamine and hydroquinone. Heat to 42℃ and stir at a stirring speed of 400rpm for 2 hours to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:8:5:4:2:0.8.

[0062] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 45°C and a casting rate of 1.5 m / min. Place the cast film along with the glass substrate into an oven and hold it at 85°C for 1.5 h. Then, raise the temperature to 155°C at a rate of 4°C / min and hold it for 1.5 h. Next, raise the temperature to 265°C at a rate of 4°C / min and hold it for 1.5 h. Finally, raise the temperature to 310°C at a rate of 1.5°C / min and hold it for 35 min. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0063] Example 3

[0064] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0065] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 60 min with an ultrasonic power of 300 W and an ultrasonic frequency of 60 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of a flexible substrate at a coating rate of 2 m / min and dried at 80 °C for 10 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 85:15:25:300. The thickness of the flexible substrate was 12 μm and the thickness of the conductive functional layer was 500 nm.

[0066] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:10. The mixture is stirred at 80°C for 30 minutes at a stirring speed of 500 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 3 m / min. The layer is pre-cured at 120°C for 2.5 h, and then heated to 130°C for 3 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 5 μm.

[0067] The method for preparing the flexible substrate layer includes the following steps:

[0068] Step 1: Under nitrogen protection at 30℃, add diamine monomer to N,N-dimethylacetamide and stir at 400 rpm for 40 min. After stirring evenly, add dianhydride monomer in 5 batches, each batch being 20% ​​of the total mass of dianhydride monomer. Stir for 20 min after each batch is added. After all the monomers are added, continue stirring for 3 h to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer and dianhydride monomer is 120:15:20. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 12:8. The dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0069] Step 2: Add polyethersulfone, polyetheretherketone, and silane-modified nano-silica to the prepolymer. After ultrasonic dispersion at 300W and 60kHz for 40 minutes, add triethylamine and hydroquinone. Heat to 45℃ and stir at 500rpm for 3 hours to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:12:8:5:3:1.

[0070] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 50°C and a casting rate of 3 m / min. Place the cast film along with the glass substrate into an oven and heat it at 90°C for 2 hours. Then, heat it to 160°C at a rate of 5°C / min and heat it for 2 hours. Next, heat it to 280°C at a rate of 5°C / min and heat it for 2 hours. Finally, heat it to 320°C at a rate of 2°C / min and heat it for 40 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0071] Comparative Example 1

[0072] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0073] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 30 min with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 0.5 m / min and dried at 60 °C for 8 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 60:5:10:200. The thickness of the flexible substrate was 5 μm and the thickness of the conductive functional layer was 200 nm.

[0074] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:5. The mixture is stirred at 60°C for 20 minutes at a stirring speed of 300 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 1 m / min. The layer is pre-cured at 100°C for 1.5 h, and then heated to 120°C for 2 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 2 μm.

[0075] The method for preparing the flexible substrate layer includes the following steps:

[0076] Step 1: At a temperature of 25℃ and under nitrogen protection, add the diamine monomer to N,N-dimethylacetamide and stir at 200 rpm for 30 minutes. After stirring evenly, add the dianhydride monomer in 5 batches, with each batch being 20% ​​of the total mass of the dianhydride monomer. Stir for 15 minutes after each batch is added. After all the monomers are added, continue stirring for 2 hours to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer, and dianhydride monomer is 100:8:10. The diamine monomer is 4,4'-bis(4-aminophenoxy)benzophenone, and the dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0077] Step 2: Add polyethersulfone, polyetheretherketone, and silane-modified nano-silica to the prepolymer. After ultrasonic dispersion for 20 min at an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz, add triethylamine and hydroquinone. Heat to 40 °C and stir at a constant temperature of 300 rpm for 1 h to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5:3:2:1:0.5.

[0078] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 40°C and a casting rate of 0.5 m / min. Place the cast film along with the glass substrate into an oven and heat it at 80°C for 1 hour. Then, heat it to 150°C at a rate of 3°C / min and heat it for 1 hour. Next, heat it to 250°C at a rate of 3°C / min and heat it for 1 hour. Finally, heat it to 300°C at a rate of 1°C / min and heat it for 30 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0079] Comparative Example 2

[0080] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0081] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 30 min with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 0.5 m / min and dried at 60 °C for 8 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 60:5:10:200. The thickness of the flexible substrate was 5 μm and the thickness of the conductive functional layer was 200 nm.

[0082] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:5. The mixture is stirred at 60°C for 20 minutes at a stirring speed of 300 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 1 m / min. The layer is pre-cured at 100°C for 1.5 h, and then heated to 120°C for 2 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 2 μm.

[0083] The method for preparing the flexible substrate layer includes the following steps:

[0084] Step 1: At a temperature of 25℃ and under nitrogen protection, add the diamine monomer to N,N-dimethylacetamide and stir at a speed of 200 rpm for 30 minutes. After stirring evenly, add the dianhydride monomer in 5 batches, with each batch being 20% ​​of the total mass of the dianhydride monomer. Stir for 15 minutes after each batch is added. After all the monomers are added, continue stirring for 2 hours to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer, and dianhydride monomer is 100:8:10. The diamine monomer is 1,3-bis(4'-aminophenoxy)benzene, and the dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0085] Step 2: Add polyethersulfone, polyetheretherketone, and silane-modified nano-silica to the prepolymer. After ultrasonic dispersion for 20 min at an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz, add triethylamine and hydroquinone. Heat to 40 °C and stir at a constant temperature of 300 rpm for 1 h to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5:3:2:1:0.5.

[0086] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 40°C and a casting rate of 0.5 m / min. Place the cast film along with the glass substrate into an oven and heat it at 80°C for 1 hour. Then, heat it to 150°C at a rate of 3°C / min and heat it for 1 hour. Next, heat it to 250°C at a rate of 3°C / min and heat it for 1 hour. Finally, heat it to 300°C at a rate of 1°C / min and heat it for 30 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0087] Comparative Example 3

[0088] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0089] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 30 min with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 0.5 m / min and dried at 60 °C for 8 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 60:5:10:200. The thickness of the flexible substrate was 5 μm and the thickness of the conductive functional layer was 200 nm.

[0090] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:5. The mixture is stirred at 60°C for 20 minutes at a stirring speed of 300 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 1 m / min. The layer is pre-cured at 100°C for 1.5 h, and then heated to 120°C for 2 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 2 μm.

[0091] The method for preparing the flexible substrate layer includes the following steps:

[0092] Step 1: Under nitrogen protection at 25℃, add diamine monomer to N,N-dimethylacetamide and stir at 200 rpm for 30 min. After stirring evenly, add dianhydride monomer in 5 batches, each batch being 20% ​​of the total mass of dianhydride monomer. Stir for 15 min after each batch is added. After all the monomers are added, continue stirring for 2 h to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer and dianhydride monomer is 100:8:10. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 5:10. The dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0093] Step 2: Add polyethersulfone, polyetheretherketone, and silane-modified nano-silica to the prepolymer. After ultrasonic dispersion for 20 min at an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz, add triethylamine and hydroquinone. Heat to 40 °C and stir at a constant temperature of 300 rpm for 1 h to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5:3:2:1:0.5.

[0094] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 40°C and a casting rate of 0.5 m / min. Place the cast film along with the glass substrate into an oven and heat it at 80°C for 1 hour. Then, heat it to 150°C at a rate of 3°C / min and heat it for 1 hour. Next, heat it to 250°C at a rate of 3°C / min and heat it for 1 hour. Finally, heat it to 300°C at a rate of 1°C / min and heat it for 30 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0095] Comparative Example 4

[0096] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0097] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 30 min with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 0.5 m / min and dried at 60 °C for 8 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 60:5:10:200. The thickness of the flexible substrate was 5 μm and the thickness of the conductive functional layer was 200 nm.

[0098] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:5. The mixture is stirred at 60°C for 20 minutes at a stirring speed of 300 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 1 m / min. The layer is pre-cured at 100°C for 1.5 h, and then heated to 120°C for 2 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 2 μm.

[0099] The method for preparing the flexible substrate layer includes the following steps:

[0100] Step 1: Under nitrogen protection at 25℃, add diamine monomer to N,N-dimethylacetamide and stir at 200 rpm for 30 min. After stirring evenly, add dianhydride monomer in 5 batches, each batch being 20% ​​of the total mass of dianhydride monomer. Stir for 15 min after each batch is added. After all the monomers are added, continue stirring for 2 h to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer and dianhydride monomer is 100:8:10. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 10:5. The dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0101] Step 2: Add polyetheretherketone and silane-modified nano-silica to the prepolymer, and ultrasonically disperse for 20 min at an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz. Then add triethylamine and hydroquinone, heat to 40 °C, and stir at a constant temperature of 300 rpm for 1 h to obtain a flexible base liquid. The mass ratio of prepolymer, polyetheretherketone, silane-modified nano-silica, triethylamine and hydroquinone is 100:8:2:1:0.5.

[0102] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 40°C and a casting rate of 0.5 m / min. Place the cast film along with the glass substrate into an oven and heat it at 80°C for 1 hour. Then, heat it to 150°C at a rate of 3°C / min and heat it for 1 hour. Next, heat it to 250°C at a rate of 3°C / min and heat it for 1 hour. Finally, heat it to 300°C at a rate of 1°C / min and heat it for 30 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0103] Comparative Example 5

[0104] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0105] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 30 min with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 0.5 m / min and dried at 60 °C for 8 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 60:5:10:200. The thickness of the flexible substrate was 5 μm and the thickness of the conductive functional layer was 200 nm.

[0106] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:5. The mixture is stirred at 60°C for 20 minutes at a stirring speed of 300 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 1 m / min. The layer is pre-cured at 100°C for 1.5 h, and then heated to 120°C for 2 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 2 μm.

[0107] The method for preparing the flexible substrate layer includes the following steps:

[0108] Step 1: Under nitrogen protection at 25℃, add diamine monomer to N,N-dimethylacetamide and stir at 200 rpm for 30 min. After stirring evenly, add dianhydride monomer in 5 batches, each batch being 20% ​​of the total mass of dianhydride monomer. Stir for 15 min after each batch is added. After all the monomers are added, continue stirring for 2 h to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer and dianhydride monomer is 100:8:10. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 10:5. The dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0109] Step 2: Add polyethersulfone and silane-modified nano-silica to the prepolymer, and ultrasonically disperse it for 20 minutes at an ultrasonic power of 200W and an ultrasonic frequency of 40kHz. Then add triethylamine and hydroquinone, heat to 40℃, and stir at a stirring speed of 300rpm for 1 hour to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, silane-modified nano-silica, triethylamine and hydroquinone is 100:8:2:1:0.5.

[0110] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 40°C and a casting rate of 0.5 m / min. Place the cast film along with the glass substrate into an oven and heat it at 80°C for 1 hour. Then, heat it to 150°C at a rate of 3°C / min and heat it for 1 hour. Next, heat it to 250°C at a rate of 3°C / min and heat it for 1 hour. Finally, heat it to 300°C at a rate of 1°C / min and heat it for 30 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0111] Comparative Example 6

[0112] A method for preparing an ultrathin flexible electronic conductor material includes the following preparation steps:

[0113] (1) Graphene, sodium dodecylbenzenesulfonate and waterborne polyurethane were added to deionized water and ultrasonically dispersed for 30 min with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to obtain a conductive slurry. The conductive slurry was coated on the surface of the flexible substrate at a coating rate of 0.5 m / min and dried at 60 °C for 8 h to form a conductive functional layer. A flexible substrate with a conductive functional layer was obtained. The mass ratio of graphene, sodium dodecylbenzenesulfonate, waterborne polyurethane and deionized water was 60:5:10:200. The thickness of the flexible substrate was 5 μm and the thickness of the conductive functional layer was 200 nm.

[0114] (2) Polyethylene terephthalate and hexafluoroisopropanol are mixed at a mass ratio of 1:5. The mixture is stirred at 60°C for 20 minutes at a stirring speed of 300 rpm until homogeneous, to obtain a polyethylene terephthalate solution. The polyethylene terephthalate solution is coated onto the surface of the conductive functional layer at a coating rate of 1 m / min. The layer is pre-cured at 100°C for 1.5 h, and then heated to 120°C for 2 h to form a protective layer, to obtain an ultra-thin flexible electronic conductor material with a protective layer, wherein the thickness of the protective layer is 2 μm.

[0115] The method for preparing the flexible substrate layer includes the following steps:

[0116] Step 1: Under nitrogen protection at 25℃, add diamine monomer to N,N-dimethylacetamide and stir at 200 rpm for 30 min. After stirring evenly, add dianhydride monomer in 5 batches, each batch being 20% ​​of the total mass of dianhydride monomer. Stir for 15 min after each batch is added. After all the monomers are added, continue stirring for 2 h to obtain the prepolymer. The mass ratio of N,N-dimethylacetamide, diamine monomer and dianhydride monomer is 100:8:10. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 10:5. The dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride.

[0117] Step 2: Add polyethersulfone, polyetheretherketone, and silane-modified nano-silica to the prepolymer. After ultrasonic dispersion for 20 min at an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz, add triethylamine and hydroquinone. Heat to 40 °C and stir at a constant temperature of 300 rpm for 1 h to obtain a flexible base liquid. The mass ratio of prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5:3:2:1:0.5.

[0118] Step 3: Cast the flexible substrate liquid onto the glass substrate using a casting machine at a temperature of 40°C and a casting rate of 0.5 m / min. Place the cast film along with the glass substrate into an oven and heat it at 80°C for 1 hour. Then, heat it to 150°C at a rate of 3°C / min and heat it for 1 hour. Next, heat it to 250°C at a rate of 3°C / min and heat it for 1 hour. Finally, heat it to 300°C at a rate of 3°C / min and heat it for 30 minutes. After cooling to room temperature, peel the film off the glass substrate to obtain the flexible substrate layer.

[0119] Performance testing

[0120] The performance of the ultrathin flexible electronic conductor materials prepared in Examples 1-3 and Comparative Examples 1-6 of this application was tested. The specific test contents are as follows:

[0121] Sheet resistance: The test was conducted according to the national standard YB / T 6166-2024 "Determination of sheet resistance of graphene film by four-probe method". The sample size was 50mm×50mm. The sample was pretreated for 24h at 23±2℃ and 50% RH. The spacing between the four probes was 1.0 mm, and the test current was 10μA.

[0122] Bending resistance: The ultra-thin flexible electronic conductor materials prepared in Examples 1-3 and Comparative Examples 1-6 were cut into strips of 50mm×10mm. Referring to the international standard IPC-TM-650 2.4.3 "Flexibility fatigue test of flexible circuit boards", the resistivity change rate was measured after 10,000 cycles of bending at a bending frequency of 30 times / min and a bending radius of 2mm.

[0123] Tensile strength and elongation at break: The test was conducted in accordance with the national standard GB / T 1040.1-2018 "Determination of tensile properties of plastics - Part 1: General". The sample size was 50 mm × 10 mm, and the tensile speed was 5 mm / min.

[0124] Solvent resistance to wiping: Referring to the national standard GB / T 23989-2009 "Determination of solvent resistance to wiping of coatings", industrial grade acetone was used as the test solvent. A lint-free gauze was used to wipe with a wiping pressure of 5N, a wiping frequency of 60 times / min (one pass for two passes), and 500 wipings were performed. The change rate of resistivity before and after wiping was measured.

[0125] The specific test results are shown in Table 1.

[0126] Table 1 Performance parameters of the ultrathin flexible electronic conductor materials prepared in Examples 1-3 and Comparative Examples 1-6

[0127] As shown in Table 1, the ultrathin flexible electronic conductor material prepared in this application has low sheet resistance, high conductivity stability, and low resistivity change rate after 10,000 bends and 500 acetone wipes, exhibiting both excellent bending resistance and solvent resistance. At the same time, the tensile strength and elongation at break are significantly improved, demonstrating excellent mechanical properties, making it suitable for long-term reliable application in flexible electronic devices.

[0128] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing an ultrathin flexible electronic conductor material, characterized in that, The preparation steps include the following: Step (1): Add conductive filler, dispersant and binder to deionized water, disperse by ultrasonication to obtain conductive slurry, coat the conductive slurry on the surface of flexible substrate, dry and cure to form conductive functional layer, and obtain flexible substrate with conductive functional layer. Step (2): Polyethylene terephthalate and hexafluoroisopropanol are mixed and stirred evenly at a temperature of 60-80℃ to obtain a polyethylene terephthalate solution; the polyethylene terephthalate solution is coated on the surface of the conductive functional layer and cured to form a protective layer, thus obtaining an ultra-thin flexible electronic conductor material with a protective layer. The method for preparing the flexible substrate layer includes the following steps: Step 1: Under the protection of an inert gas at a temperature of 25-30℃, add the diamine monomer to N,N-dimethylacetamide and stir until homogeneous. Then add the dianhydride monomer in 5 batches, stirring for 15-20 minutes after each batch is added. After all the monomers are added, continue stirring for 2-3 hours to obtain the prepolymer. Step 2: Add polyethersulfone, polyetheretherketone and silane-modified nano silica to the prepolymer, disperse by ultrasonication, add triethylamine and hydroquinone, heat to 40-45℃, stir at constant temperature for 1-3 hours to obtain flexible base liquid; Step 3: The flexible base liquid is cast onto a glass substrate using a casting machine. The cast film and the glass substrate are placed in an oven for gradient heating imidization. After cooling to room temperature, the film is peeled off from the glass substrate to obtain a flexible base layer. The diamine monomer is composed of 1,3-bis(4'-aminophenoxy)benzene and 4,4'-bis(4-aminophenoxy)benzophenone in a mass ratio of 10-12:5-8; the dianhydride monomer is 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

2. The method for preparing the ultrathin flexible electronic conductor material according to claim 1, characterized in that, In step (1), the mass ratio of the conductive filler, dispersant, binder and deionized water is 60-85: 5-15: 10-25: 200-300.

3. The method for preparing the ultrathin flexible electronic conductor material according to claim 1, characterized in that, In step (1), the conductive filler is selected from one or more of silver nanowires, graphene, and reduced graphene oxide; the dispersant is selected from one or more of sodium dodecylbenzenesulfonate, polyethylene glycol, and polyvinylpyrrolidone; and the binder is selected from one or more of waterborne polyurethane, polyimide, and epoxy resin.

4. The method for preparing the ultrathin flexible electronic conductor material according to claim 1, characterized in that, In step (2), the curing process specifically involves pre-curing at 100-110℃ for 1.5-2.5 hours, followed by heating to 120-130℃ for 2-3 hours of constant temperature curing.

5. The method for preparing the ultrathin flexible electronic conductor material according to claim 1, characterized in that, In step 1, the mass ratio of N,N-dimethylacetamide, diamine monomer, and dianhydride monomer is 100-120:8-15:10-20.

6. The method for preparing the ultrathin flexible electronic conductor material according to claim 1, characterized in that, In step 2, the mass ratio of the prepolymer, polyethersulfone, polyetheretherketone, silane-modified nano-silica, triethylamine, and hydroquinone is 100:5-12:3-8:2-5:1-3:0.5-1.

7. The method for preparing the ultrathin flexible electronic conductor material according to claim 1, characterized in that, In step 3, the specific heating program for the gradient heating imidization is as follows: after holding at 80-90℃ for 1-2 hours, the temperature is increased to 150-160℃ at a heating rate of 3-5℃ / min, and held for 1-2 hours; then the temperature is increased to 250-280℃ at a heating rate of 3-5℃ / min, and held for 1-2 hours; finally, the temperature is increased to 300-320℃ at a heating rate of 1-2℃ / min, and held for 30-40 minutes.

8. An ultrathin flexible electronic conductor material, characterized in that, The ultrathin flexible electronic conductor material is prepared by the preparation method according to any one of claims 1-7; The thickness of the flexible substrate layer is 5-12 μm; the thickness of the conductive functional layer is 200-500 nm; and the thickness of the protective layer is 2-5 μm.

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