Preparation method of all-aqueous electrochromic synthetic leather

Abstract

The application discloses a preparation method of a full-water-based electrochromic synthetic leather, and comprises the following steps: pretreating a water-based base; coating a water-based conductive slurry on the surface of the water-based base to form a water-based conductive layer through pre-baking and curing; coating a water-based electrochromic slurry to form a water-based electrochromic layer; coating a water-based gel electrolyte slurry to form a water-based gel electrolyte layer; hot-pressing and compounding a counter electrode and the water-based gel electrolyte layer to form a multilayer sandwich structure; packaging the edges of the multilayer sandwich structure by using a water-based sealing glue, and then coating a water-based transparent scratch-resistant polyurethane protective layer on the surface of the counter electrode, so as to obtain the full-water-based electrochromic synthetic leather. The complete preparation process of the synthetic leather is constructed through six steps, and zero VOC emission is realized. The electrochromic technology is combined with the synthetic leather material, the prepared electrochromic synthetic leather not only retains the soft, wear-resistant and easy-to-cut features of the synthetic leather itself, but also is endowed with the electrically controllable color switching function, and the personalized needs of one-key color changing can be realized.

Description

Technical Field

[0001] This invention relates to the field of synthetic leather technology, specifically to a method for preparing all-water-based electrochromic synthetic leather. Background Technology

[0002] Synthetic leather, as an ideal substitute for natural leather, has been widely used in automotive interiors, footwear, apparel, and bags. Electrochromic technology is an intelligent technology that utilizes the reversible changes in the optical properties (color, transparency) of materials under the influence of an external electric field. Its core principle is that electrochromic materials undergo an oxidation-reduction reaction under electric field excitation, leading to changes in the material's electronic structure and thus achieving reversible color switching. This process boasts advantages such as low power consumption, rapid response, and stable switching, and has already achieved initial applications in areas such as intelligent building windows, automotive anti-glare rearview mirrors, and aircraft windows. With the upgrading of consumption, functionalization and intelligence have become the core development trends of the synthetic leather industry. Electrochromic synthetic leather, due to its ability to achieve personalized functions such as one-click color changing and intelligent dimming, has broad application prospects in high-end automotive interiors and smart wearables. However, integrating electrochromic functionality into the manufacturing process of synthetic leather presents the following technical challenges: Firstly, interlayer bonding is difficult. Synthetic leather substrate is a flexible polymer material with low surface energy, resulting in poor adhesion between it and the functional coatings. Existing processes struggle to achieve a strong bond between the functional layers while maintaining flexibility, making it prone to delamination and open circuit failure after bending, leading to a short product lifespan.

[0003] Secondly, it is difficult to balance environmental protection and performance. Traditional preparation processes often rely on organic solvent systems to ensure the density and adhesion of the coating film, but this leads to environmental problems such as excessive VOC emissions and solvent residue. Simply replacing it with a water-based system results in insufficient film density, susceptibility of the coating to external moisture erosion, and poor stability of the electrochromic layer. As a result, a mature and reliable all-water-based process solution has yet to be developed.

[0004] Third, the process is complex and the stability is poor. The electrolyte layer mostly uses liquid materials, which makes encapsulation difficult. The leakage problem has not been effectively solved for a long time, which seriously affects the reliability of the device and the feasibility of mass production. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides a method for preparing fully water-based electrochromic synthetic leather. The method employs a six-step process to construct a complete preparation flow for fully water-based electrochromic synthetic leather, using water as the dispersion medium throughout the process to achieve zero VOC emissions. By combining electrochromic technology with synthetic leather materials, the resulting electrochromic synthetic leather retains the inherent softness, wear resistance, and ease of cutting of synthetic leather, while also providing an electrically controllable color-changing function, enabling personalized color changes with a single click.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a fully water-based electrochromic synthetic leather, comprising the following steps: Step 1: Degreasing and dust removal treatment of the water-based substrate, followed by corona treatment or plasma treatment; Step 2: Coating the pretreated water-based conductive slurry onto the surface of the water-based substrate, followed by pre-baking and curing to form a water-based conductive layer; Step 3: Coating the surface of the water-based electrochromic slurry onto the surface of the water-based conductive layer, followed by drying to form a water-based electrochromic layer; Step 4: Coating the surface of the water-based electrochromic gel slurry onto the surface of the water-based electrochromic layer, followed by drying to form a water-based gel electrolyte layer; Step 5: Hot-pressing the counter electrode with the water-based gel electrolyte layer to form a multilayer sandwich structure; Step 6: Encapsulating the edges of the multilayer sandwich structure with water-based sealant, then coating the surface of the counter electrode with a water-based transparent scratch-resistant polyurethane protective layer, followed by drying to obtain the fully water-based electrochromic synthetic leather.

[0007] Furthermore, in step two, the aqueous conductive layer slurry comprises, by mass parts: 10-30 parts of aqueous carbon nanotube dispersion or aqueous graphene dispersion, 60-80 parts of aqueous polyurethane emulsion, 10-20 parts of deionized water, and 0.2-0.5 parts of aqueous leveling agent; the coating is performed by scraping, roller coating, or gravure coating; the pre-baking temperature is 80-90℃ for 3-5 minutes, the curing temperature is 110-130℃ for 3-5 minutes; and the sheet resistivity of the aqueous conductive layer is 15-45 Ω / sq.

[0008] Furthermore, in step three, the aqueous electrochromic layer slurry comprises, by mass parts: 15-25 parts of one or more of the following: water-soluble polyaniline dispersion, aqueous polythiophene dispersion, or aqueous polypyrrole dispersion; 60-75 parts of aqueous polyurethane emulsion; 10-20 parts of deionized water; and 0.5-1 parts of aqueous crosslinking agent; the wet film thickness after coating is 18-22 μm, the drying temperature is 70-80℃, and the drying time is 5-10 min; the aqueous crosslinking agent is an aqueous isocyanate crosslinking agent or an aqueous epoxy crosslinking agent.

[0009] Furthermore, in step four, the aqueous gel electrolyte slurry comprises, by mass parts: 50-60 parts of an 8-12% concentration PVA aqueous solution, 5-10 parts of a lithium salt aqueous solution, 20-30 parts of an aqueous acrylic emulsion, and 10-15 parts of deionized water; the wet film thickness after coating is 35-40 μm, the drying temperature is 60-70℃, and the drying time is 5-8 min; the lithium salt aqueous solution is a LiCl aqueous solution or a LiTFSI aqueous solution with a concentration of 5-10%.

[0010] Furthermore, in step five, the hot-pressing composite temperature is 70-90℃, the pressure is 0.2-0.5MPa, and the time is 3-5min; the thickness of the counter electrode is 15-25μm.

[0011] Furthermore, in step six, the wet film thickness of the water-based transparent scratch-resistant polyurethane protective layer is 20-30 μm, the drying temperature is 80-100℃, and the time is 5-8 min; the thickness of the water-based edge encapsulation is 1.0-1.3 mm.

[0012] Furthermore, the water-based substrate is water-based polyurethane synthetic leather or water-based microfiber leather, and the thickness of the water-based substrate is 1.0±0.1mm.

[0013] Furthermore, the performance indicators of the all-water-based electrochromic synthetic leather are as follows: working voltage 1.5-3V, color change response time 1-3s, cycle life ≥5000 times, no cracking or peeling after 10000 bends with R=5mm, adhesion level 0 in cross-cut adhesion test, and zero VOC emissions.

[0014] The method for preparing all-water-based electrochromic synthetic leather of the present invention has the following beneficial effects: 1. First, a complete synthetic leather manufacturing process was constructed through six steps: substrate pretreatment, conductive layer preparation, electrochromic layer preparation, gel electrolyte layer preparation, electrode lamination, edge encapsulation, and surface protection. Water was used as the dispersion medium throughout the process, avoiding the use of organic solvents and achieving zero VOC emissions. Second, by combining electrochromic technology with synthetic leather materials, the resulting electrochromic synthetic leather retains the inherent properties of synthetic leather, such as softness, wear resistance, and ease of cutting, while also providing electrically controllable color switching functionality, enabling personalized needs such as one-click color changing and intelligent dimming. Finally, the layers are tightly bonded together through layered coating and hot-press lamination, ensuring the structural integrity of the synthetic leather product and the reliability of the electrochromic function.

[0015] 2. The all-water-based electrochromic synthetic leather utilizes all-water-based materials and a multi-layered structure. From the base, conductive layer, electrochromic layer, gel electrolyte layer to the encapsulation and protective layer, all components are water-based, with no added or emitted organic solvents. VOC emissions are zero, and there are no odors or heavy metal residues, complying with national environmental policies and global green development concepts. The synthetic leather product comprises a six-layer structure: base, conductive layer, electrochromic layer, gel electrolyte layer, counter electrode, and scratch-resistant protective layer. Each layer has a clearly defined function and compatible materials: the conductive layer provides a uniform electric field; the electrochromic layer undergoes an oxidation-reduction reaction under electric field excitation to achieve color change; the gel electrolyte layer provides ion transport channels, forming a closed loop with the counter electrode; and the encapsulation and scratch-resistant protective layer ensure stability. The synergistic effect of each layer achieves highly efficient and reliable electrochromic performance. Synthetic leather products can be driven by low voltage (1.5-3V), with a color change response time of 1-3 seconds, a cycle life of ≥5000 cycles, and no significant color decay. A good balance is achieved between response speed and cycle life, meeting practical application requirements. Simultaneously, synthetic leather products possess flexibility, environmental friendliness, and electronically controlled color change properties, making them widely applicable in footwear, bags, clothing, automotive interiors, smart wearables, military camouflage, and many other fields. They meet market demands for intelligent and environmentally friendly products and have broad market application prospects. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the all-water-based electrochromic synthetic leather of the present invention.

[0017] Figure reference numerals: 1. Aqueous substrate; 2. Aqueous conductive layer; 3. Aqueous electrochromic layer; 4. Aqueous gel electrolyte layer; 5. Counter electrode; 6. Aqueous edge encapsulation layer; 7. Aqueous transparent scratch-resistant protective layer. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0019] Please see the appendix Figure 1This embodiment provides a fully water-based electrochromic synthetic leather, comprising, from bottom to top: a water-based substrate 1; a water-based conductive layer 2 disposed on the water-based substrate 1; a water-based electrochromic layer 3 disposed on the water-based conductive layer 2; a water-based gel electrolyte layer 4 disposed on the water-based electrochromic layer 3; a counter electrode 5 disposed on the water-based gel electrolyte layer 4; a water-based edge encapsulation layer 6, wherein the water-based substrate 1, water-based conductive layer 2, water-based electrochromic layer 3, water-based gel electrolyte layer 4, and counter electrode 5 form a multi-layer sandwich structure, and the water-based edge encapsulation layer 6 encapsulates both sides of the multi-layer sandwich structure; and a water-based transparent scratch-resistant protective layer 7 disposed on the surface of the counter electrode 5; wherein the water-based conductive layer 2, water-based electrochromic layer 3, water-based gel electrolyte layer 4, counter electrode 5, water-based edge encapsulation layer 6, and water-based transparent scratch-resistant protective layer 7 are all fully water-based materials and do not contain organic solvents.

[0020] In this embodiment, the all-water-based electrochromic synthetic leather, from base 1 to layers, and then to encapsulation and protection, relies on the support of the previous layer, and their functions are mutually matched. The distribution logic of each layer is as follows: Water-based base 1: The base carrier of the entire synthetic leather, at the bottom, supporting all the upper layers; Aqueous conductive layer 2: Directly coated on aqueous substrate 1, providing a uniform conductive path for the upper electrochromic layer 3. If it is moved to another location, electrochromic driving cannot be achieved. Electrochromic layer 3: As the core color-changing layer, it must be above the conductive layer 2 (to receive the voltage signal from the conductive layer 2) and below the aqueous gel electrolyte layer 4 (to achieve ion exchange in contact with the electrolyte layer). If the position is misaligned, it will not be able to change color. Aqueous gel electrolyte layer 4: It needs to be sandwiched between electrochromic layer 3 and counter electrode 5 to provide ion transport channels and is the medium for electrochromic reaction. If it is replaced, ions cannot be inserted or extracted normally, and the color-changing function will fail. Counter electrode 5: To form a closed circuit with conductive layer 2, it must be on top of aqueous gel electrolyte layer 4; otherwise, a circuit cannot be formed and the electrochromic reaction cannot be driven. Water-based edge sealing layer 6: Used to seal edges and prevent moisture or ion loss; it needs to be installed at the edges of multi-layer sandwich structures. Water-based transparent scratch-resistant protective layer 7: Must be on top, used for scratch resistance, weather resistance, and waterproofing.

[0021] The synthetic leather of this invention is constructed by using an aqueous base 1, an aqueous conductive layer 2, an aqueous electrochromic layer 3, an aqueous gel electrolyte layer 4, a counter electrode 5, an aqueous transparent scratch-resistant protective layer 7, and all layers being made of aqueous materials. This results in a complete structure and functionally matched all-aqueous electrochromic synthetic leather. The structural distribution ensures that the aqueous conductive layer 2 provides a voltage signal to the aqueous electrochromic layer 3, the aqueous gel electrolyte layer 4 provides an ion transport channel, and the counter electrode 5 forms a closed circuit with the conductive layer 2. The synergistic effect of each layer achieves the electrochromic function, while the all-aqueous materials ensure environmental friendliness.

[0022] The aqueous substrate 1 has a basis weight of 400-600 g / m³. 2 The water-soluble microfiber has a width of ≥146cm and a thickness of 1.0±0.1mm. The water-soluble microfiber ensures that the water-based substrate 1 possesses suitable mechanical strength and flexibility to support the upper layers, while also exhibiting good compatibility with the water-based coating, meeting the performance requirements of substrate 1 for applications such as footwear, bags, and automotive interiors.

[0023] Preferably, the water-based microfiber leather (water-soluble microfiber) uses nylon nonwoven fabric from Ningbo Hengqide Chemical Fiber Technology Co., Ltd., which is composed of 60% nylon and 40% W polyurethane, with the following physical properties:

[0024] The sheet resistivity of the aqueous conductive layer 2 is 15-45 Ω / sq; too low a sheet resistivity will increase costs, while too high a sheet resistivity will affect driving efficiency. This range has been verified by examples to enable low-voltage (1.5-3V) rapid driving. The aqueous conductive layer 2 is composed of an aqueous carbon nanotube dispersion or an aqueous graphene dispersion and an aqueous polyurethane emulsion, exhibiting uniform conductivity and good flexibility. The wet film thickness of the aqueous conductive layer 2 is 25-35 μm.

[0025] The wet film thickness of the aqueous electrochromic layer 3 is 18-22 μm, and it is composed of one or more of water-soluble polyaniline, water-based polythiophene, or water-based polypyrrole, combined with an aqueous polyurethane emulsion and an aqueous crosslinking agent. The introduction of the aqueous crosslinking agent enhances the bonding strength between the aqueous electrochromic layer 3 and the aqueous conductive layer 2, ensuring the durability and stability of the aqueous electrochromic layer 3. Preferably, the aqueous crosslinking agent is an aqueous isocyanate crosslinking agent or an aqueous epoxy crosslinking agent.

[0026] The aqueous gel electrolyte layer 4 has a wet film thickness of 35-40 μm and is composed of PVA, lithium salt, and aqueous acrylic emulsion, forming a semi-solid ion transport medium. Preferably, the lithium salt is LiCl or LiTFSI. The gel system of the aqueous gel electrolyte layer 4 combines good ionic conductivity and mechanical stability, solving the problem of easy leakage of liquid electrolytes, while ensuring efficient ion transport between the aqueous electrochromic layer 3 and the counter electrode 5, achieving a fast response of 1-3 seconds.

[0027] The counter electrode 5 is an aqueous conductive cloth or aqueous conductive film with a thickness of 15-25 μm, providing a flexible and conductive counter electrode layer that forms a closed circuit with the aqueous conductive layer 2. The counter electrode 5, made of aqueous material, is tightly bonded to the gel electrolyte layer 4 through hot-pressing, ensuring the stability of the circuit and the flexibility of the synthetic leather.

[0028] Edge sealing is crucial for the stability of flexible electrochromic synthetic leather. The water-based edge sealing layer 6, with a thickness of 1.0-1.3 mm, is located at the edge of the multi-layered sandwich structure. This layer effectively seals the inner layers, preventing moisture intrusion and electrolyte ion loss, thus extending the lifespan of the synthetic leather product. The water-based transparent scratch-resistant protective layer 7 has a wet film thickness of 20-30 μm and a hardness ≥2H after drying. It provides surface abrasion resistance, weather resistance, and waterproof protection, preventing the electrochromic layer 3 from being easily corroded by external factors, while maintaining the transparency and flexibility of the synthetic leather product.

[0029] The fully water-based electrochromic synthetic leather operates at a voltage of 1.5-3V, with a color-changing response time of 1-3s, a cycle life of ≥5000 cycles, and can withstand 10,000 bends with a radius of 5mm without cracking or peeling. Its adhesion in a cross-cut adhesion test is rated at level 0, and its VOC emissions are zero. It requires only a 1.5-3V low-voltage DC power supply to drive the color change and can be directly adapted to button batteries, lithium batteries, or a 12V automotive power system (via a step-down module), meeting the low power consumption and high safety requirements of applications such as automotive interiors and smart wearables.

[0030] The all-water-based electrochromic synthetic leather of this invention can be applied to footwear, bags, clothing, automotive interiors, smart wearables, or military camouflage. Example 2

[0031] This example provides a method for preparing all-water-based electrochromic synthetic leather, including the following steps: Step 1: Degrease and remove dust from water-based substrate 1, then perform corona treatment or plasma treatment; Step 2: Apply the water-based conductive paste to the surface of the pretreated water-based substrate 1, and then pre-bake and cure it to form the water-based conductive layer 2; Step 3: Coat the surface of the water-based electrochromic paste onto the surface of the water-based conductive layer 2, and dry it to form the water-based electrochromic layer 3; Step 4: Coat the surface of the aqueous gel electrolyte slurry onto the aqueous electrochromic layer 3, and dry it to form the aqueous gel electrolyte layer 4; Step 5: The counter electrode and the aqueous gel electrolyte layer 4 are hot-pressed together to form a multi-layer sandwich structure; Step 6: Use water-based sealant to seal the edges of the multi-layer sandwich structure, then coat the surface of the counter electrode 5 with a water-based transparent scratch-resistant polyurethane protective layer 7, and dry it to obtain a fully water-based electrochromic synthetic leather.

[0032] The preparation method of this embodiment first involves six steps: substrate pretreatment, conductive layer preparation, electrochromic layer preparation, gel electrolyte layer preparation, electrode lamination, edge encapsulation, and surface protection. This forms a complete synthetic leather preparation process, using water as the dispersion medium throughout to avoid the use of organic solvents and achieve zero VOC emissions. Secondly, by combining electrochromic technology with synthetic leather materials, the resulting electrochromic synthetic leather retains the inherent properties of synthetic leather, such as softness, wear resistance, and ease of cutting, while also providing electrically controllable color switching functionality, enabling personalized needs such as one-click color changing and intelligent dimming. Finally, the layers are tightly bonded together through layered coating and hot-press lamination, ensuring the structural integrity of the synthetic leather product and the reliability of the electrochromic function. This invention's preparation method is simple, environmentally friendly, and controllable. The resulting all-water-based electrochromic synthetic leather can be widely used in footwear, bags, clothing, automotive interiors, smart wearables, military camouflage, and other fields, demonstrating significant industrial practical value.

[0033] In step two, the aqueous conductive slurry comprises, by weight, 10-30 parts of aqueous carbon nanotube dispersion or aqueous graphene dispersion (10% solid content), 60-80 parts of aqueous polyurethane emulsion (30% solid content), 10-20 parts of deionized water, and 0.2-0.5 parts of aqueous leveling agent (BYK-306). The coating is applied by scraping, roller coating, or gravure coating. The pre-baking temperature is 80-90℃ for 3-5 minutes, and the curing temperature is 110-130℃ for 3-5 minutes, achieving good adhesion between the conductive layer 2 and the substrate 1. The sheet resistivity of the aqueous conductive layer 2 is 15-45 Ω / sq, providing a stable and uniform conductive path for the electrochromic layer 3. Simultaneously, the use of an aqueous system avoids the VOC emission problems associated with traditional oil-based conductive layers.

[0034] In step three, the aqueous electrochromic slurry comprises, by mass parts: 15-25 parts (solid content 15%) of one or more of water-soluble polyaniline dispersion, aqueous polythiophene dispersion, or aqueous polypyrrole dispersion; 60-75 parts of aqueous polyurethane emulsion; 10-20 parts of deionized water; and 0.5-1 parts of aqueous crosslinking agent. After coating, the wet film thickness is 18-22 μm, the drying temperature is 70-80℃, and the drying time is 5-10 min, forming a crack-free and dense aqueous electrochromic layer 3, which can achieve an adhesion grade of 0 and no abnormalities after 10,000 bends.

[0035] Preferably, the aqueous crosslinking agent is an aqueous isocyanate crosslinking agent or an aqueous epoxy crosslinking agent. The introduction of the aqueous crosslinking agent significantly improves the bonding strength between the electrochromic layer 3 and the conductive layer 2.

[0036] In step four, the aqueous gel electrolyte slurry comprises, by mass parts: 50-60 parts of an 8-12% concentration PVA aqueous solution (PVA molecular weight 1700), 5-10 parts of a lithium salt aqueous solution, 20-30 parts of an aqueous acrylic emulsion, and 10-15 parts of deionized water; after coating, the wet film thickness is 35-40 μm, the drying temperature is 60-70℃, and the time is 5-8 min, forming a semi-solid gel electrolyte. The gel electrolyte can prevent leakage and ensure the long-term stable operation of synthetic leather, while the response time is maintained at 1-3 s, solving the problems of easy leakage, corrosion, and poor stability of traditional liquid electrolytes.

[0037] Preferably, the lithium salt aqueous solution is a LiCl aqueous solution or a LiTFSI aqueous solution with a concentration of 5-10%.

[0038] In step five, the hot-pressing composite temperature is 70-90℃, the pressure is 0.2-0.5MPa, and the time is 3-5min; this achieves a tight bond between the counter electrode 5 and the gel electrolyte layer 4, forming a stable sandwich structure. This process is mild, suitable for flexible substrates, avoids damage to the aqueous layer caused by high temperature and high pressure, and ensures that the counter electrode 5 and the conductive layer 2 form a closed circuit, driving the electrochromic reaction to proceed normally. Preferably, the thickness of the counter electrode 5 is 15-25μm.

[0039] In step six, the wet film thickness of the water-based transparent scratch-resistant polyurethane protective layer 7 is 20-30 μm, the solid content of the polyurethane is 25%, the drying temperature is 80-100℃, and the drying time is 5-8 min. The transparent scratch-resistant polyurethane protective layer 7 provides surface protection, preventing the water-based system from being corroded by the outside world, while maintaining the flexibility of the product. The thickness of the water-based edge seal is 1.0-1.3 mm. The water-based edge seal can prevent water vapor intrusion and ion loss.

[0040] The water-based substrate 1 is water-based polyurethane synthetic leather or water-based microfiber leather, with a thickness of 1.0±0.1mm, ensuring good compatibility between the substrate 1 and each water-based layer. The compatibility of the all-water-based material system results in excellent adhesion between the coatings. Through the pretreatment of the substrate 1 and the reasonable selection of the substrate 1 material, adhesion level 0 and no abnormalities after 10,000 bends are achieved.

[0041] The performance indicators of the all-water-based electrochromic synthetic leather are as follows: working voltage 1.5-3V, color change response time 1-3s, cycle life ≥5000 times, no cracking or peeling after 10000 bends with R=5mm, adhesion level 0 in cross-cut adhesion test, and zero VOC emissions.

[0042] The beneficial effects of the all-water-based electrochromic synthetic leather of the present invention will be explained below through several experimental and control groups.

[0043] Experimental group 1 This experimental group provides a fully water-based electrochromic synthetic leather, comprising, from bottom to top: a water-based substrate, a water-based conductive layer, a water-based electrochromic layer, a water-based gel electrolyte layer, a counter electrode, a water-based transparent scratch-resistant protective layer, and a water-based edge encapsulation layer encapsulated on both sides of the multi-layered sandwich structure. The preparation method of this fully water-based electrochromic synthetic leather includes the following steps: Step 1: Take water-based polyurethane synthetic leather as the base, first remove surface oil with degreaser, then wipe it with a lint-free cloth to remove dust, and use corona treatment to improve the surface energy of the base. The treatment power is 300W and the treatment time is 30s. Set aside. Step 2: Take 15 parts by weight of aqueous carbon nanotube dispersion (10% solid content), 70 parts by weight of aqueous polyurethane emulsion (30% solid content), 14 parts by weight of deionized water, and 0.3 parts by weight of aqueous leveling agent. Put them into a mixing tank and stir evenly at 300 r / min. After vacuum degassing for 15 min, apply the mixture to the surface of the pretreated aqueous polyurethane synthetic leather by scraping. The wet film thickness is 30 μm. First, pre-bake at 85℃ for 4 min, and then cure at 120℃ for 4 min. The sheet resistance of the conductive layer is measured to be 25 Ω / sq. Step 3: Take 20 parts by weight of water-soluble polyaniline dispersion (15% solid content), 65 parts of water-based polyurethane emulsion, 14 parts of deionized water, and 0.7 parts of water-based isocyanate crosslinking agent, stir evenly, and coat the surface of the water-based conductive layer by roller coating. The wet film thickness is 20 μm. Dry at 75°C for 8 min to form an electrochromic layer. Step 4: Take 55 parts by weight of 10% PVA aqueous solution (molecular weight 1700), 8 parts by weight of 5% LiCl aqueous solution, 25 parts by weight of aqueous acrylic emulsion, and 12 parts by weight of deionized water. Stir until transparent and homogeneous to form an aqueous gel electrolyte. Coat the electrolyte evenly on the surface of the electrochromic layer using a gravure coating method. The wet film thickness is 40 μm. Dry at 65℃ for 6 min. Step 5: Composite counter electrode: The aqueous conductive cloth and the aqueous gel electrolyte layer are hot-pressed together at a temperature of 80℃, a pressure of 0.3MPa, and a time of 4min to form a sandwich structure. Step 6: Water-based encapsulation and surface protection: The edges of the sandwich structure are sealed with water-based sealant with a sealing width of 1 mm. Then, a water-based transparent scratch-resistant polyurethane protective layer (25% solid content) is coated on the electrode surface with a wet film thickness of 25 μm. The film is dried at 90°C for 6 min to obtain water-soluble water-based electrochromic synthetic leather. Step 7: Cut the synthetic leather into 5cm × 5cm samples. Lead wires from the water-based conductive layer and the counter electrode using conductive tape. Connect the wires to a DC regulated power supply and set the voltage to 2.0V. After power is applied, the electrochromic layer undergoes a redox reaction under the electric field, changing its color from the original light green to dark blue (due to polyaniline). The original color is restored after the power is disconnected or a reverse voltage is applied. Testing showed a coloring response time of 1.8s, a fading response time of 1.5s, and no significant decay in color-changing performance after 5000 cycles.

[0044] Experimental group 2 This experimental group provides a fully water-based electrochromic synthetic leather, comprising, from bottom to top: a water-based substrate, a water-based conductive layer, a water-based electrochromic layer, a water-based gel electrolyte layer, a counter electrode, a water-based transparent scratch-resistant protective layer, and a water-based edge encapsulation layer encapsulated on both sides of the multi-layered sandwich structure. The preparation method of this fully water-based electrochromic synthetic leather includes the following steps: Step 1: Take water-based microfiber leather as the base, first use degreaser to remove surface oil stains, then wipe it with a lint-free cloth to remove dust, and use plasma treatment to improve the surface energy of the base. The treatment power is 400W and the treatment time is 25s. Set aside. Step 2: Take 25 parts by weight of waterborne graphene dispersion (10% solid content), 65 parts by weight of waterborne polyurethane emulsion (30% solid content), 10 parts by weight of deionized water, and 0.5 parts by weight of waterborne leveling agent. Put them into a mixing tank and stir evenly at 300 r / min. After vacuum degassing for 20 min, apply the mixture to the surface of the pretreated waterborne microfiber leather using a gravure coating method. The wet film thickness is 25 μm. First, pre-bake at 85℃ for 5 min, and then cure at 110℃ for 5 min. The sheet resistance of the conductive layer is measured to be 15 Ω / sq. Step 3: Take 22 parts by weight of aqueous polythiophene dispersion (15% solid content), 60 parts of aqueous polyurethane emulsion, 17 parts of deionized water, and 1 part of aqueous epoxy crosslinking agent. After stirring evenly, coat the aqueous conductive layer with a wet film thickness of 18 μm. Dry at 70°C for 10 min to form an electrochromic layer. Step 4: Take 50 parts by weight of 10% PVA aqueous solution (molecular weight 1700), 10 parts by weight of 8% LiTFSI aqueous solution, 20 parts by weight of aqueous acrylic emulsion, and 10 parts by weight of deionized water. Stir until transparent and homogeneous to form an aqueous gel electrolyte. Coat the electrolyte evenly on the surface of the electrochromic layer using a coating method. The wet film thickness is 35 μm. Dry at 60℃ for 8 min. Step 5: Hot-press the aqueous conductive film and the aqueous gel electrolyte layer together at a temperature of 70°C, a pressure of 0.5 MPa, and a time of 3 min to form a sandwich structure. Step 6: Water-based encapsulation and surface protection: The edges of the sandwich structure are sealed with water-based sealant with a sealing width of 1 mm. Then, a water-based transparent scratch-resistant polyurethane protective layer (25% solid content) is coated on the electrode surface with a wet film thickness of 20 μm. The film is dried at 80°C for 8 min to obtain water-soluble water-based electrochromic synthetic leather. Step 7: Cut the synthetic leather into 5cm × 5cm samples, and extend wires from the water-based conductive layer and the counter electrode using conductive tape. Connect the wires to a DC regulated power supply and set the voltage to 1.5V. After power is applied, the electrochromic layer undergoes a redox reaction under the electric field, changing its color from the original light green to blue (due to polythiophene); after disconnecting the power supply or applying a reverse voltage, the original color is restored. Testing showed a coloring response time of 1.5s, a fading response time of 1.2s, and no significant decay in color-changing performance after 6000 cycles.

[0045] Experimental group 3 This experimental group provides a fully water-based electrochromic synthetic leather, comprising, from bottom to top: a water-based substrate, a water-based conductive layer, a water-based electrochromic layer, a water-based gel electrolyte layer, a counter electrode, a water-based transparent scratch-resistant protective layer, and a water-based edge encapsulation layer encapsulated on both sides of the multi-layered sandwich structure. The preparation method of this fully water-based electrochromic synthetic leather includes the following steps: Step 1: Take water-based polyurethane synthetic leather as the base, first remove surface oil with degreaser, then wipe it with a lint-free cloth to remove dust, and use corona treatment to improve the surface energy of the base. The treatment power is 350W and the treatment time is 35s. Set aside. Step 2: Take 10 parts by weight of aqueous carbon nanotube dispersion (10% solid content), 80 parts by weight of aqueous polyurethane emulsion (30% solid content), 20 parts by weight of deionized water, and 0.2 parts by weight of aqueous leveling agent. Put them into a mixing tank and stir evenly at 300 r / min. After vacuum degassing for 15 min, apply the mixture to the surface of the pretreated aqueous polyurethane synthetic leather using a roller coating method. The wet film thickness is 35 μm. First, pre-bake at 89℃ for 3 min, and then cure at 130℃ for 3 min. The sheet resistance of the conductive layer is measured to be 45 Ω / sq. Step 3: Take 15 parts by weight of aqueous polypyrrole dispersion (15% solid content), 75 parts of aqueous polyurethane emulsion, 10 parts of deionized water, and 0.5 parts of aqueous isocyanate crosslinking agent. After stirring evenly, coat the aqueous conductive layer with a wet film thickness of 22 μm. Dry at 80℃ for 5 min to form an electrochromic layer. Step 4: Take 60 parts by weight of 10% PVA aqueous solution (molecular weight 1700), 5 parts by weight of 10% LiCl aqueous solution, 30 parts by weight of aqueous acrylic emulsion, and 15 parts by weight of deionized water. Stir until transparent and homogeneous to form an aqueous gel electrolyte. Coat the electrolyte evenly on the surface of the electrochromic layer using a coating method. The wet film thickness is 38 μm. Dry at 67℃ for 7 min. Step 5: Composite counter electrode: The aqueous conductive cloth and the aqueous gel electrolyte layer are hot-pressed together at a temperature of 90℃, a pressure of 0.2MPa, and a time of 5min to form a sandwich structure. Step 6: Water-based encapsulation and surface protection: The edges of the sandwich structure are sealed with water-based sealant with a sealing width of 1 mm. Then, a water-based transparent scratch-resistant polyurethane protective layer (25% solid content) is coated on the electrode surface with a wet film thickness of 30 μm. The film is dried at 100℃ for 5 min to obtain water-soluble water-based electrochromic synthetic leather. Step 7: Cut the synthetic leather into 5cm × 5cm samples, and extend wires from the water-based conductive layer and the counter electrode using conductive tape. Connect the wires to a DC regulated power supply and set the voltage to 3.0V. After power is applied, the electrochromic layer undergoes a redox reaction under the electric field, changing its color from the original light gray to dark blue (due to polypyrrole); after disconnecting the power supply or applying a reverse voltage, the original color is restored. Testing showed a coloring response time of 2.8s, a fading response time of 2.5s, and no significant decay in color-changing performance after 5500 cycles.

[0046] Comparison Group 1 This comparative group provides an electrochromic synthetic leather, comprising, from bottom to top: a substrate, a conductive layer, an electrochromic layer, a gel electrolyte layer, a counter electrode, a transparent scratch-resistant protective layer, and an edge encapsulation layer encapsulated on both sides of the multilayer sandwich structure. The preparation method of this electrochromic synthetic leather includes the following steps: Step 1: Take water-based polyurethane synthetic leather as the base, first remove surface oil with degreaser, then wipe it with a lint-free cloth to remove dust, and use corona treatment to improve the surface energy of the base. The treatment power is 300W and the treatment time is 30s. Set aside. Step 2: Take 15 parts by weight of oily carbon nanotube dispersion (10% solid content), 70 parts of oily polyurethane emulsion (30% solid content), 14 parts of deionized water, and 0.3 parts of water-based leveling agent, put them into a mixing tank, stir evenly at 300 r / min, vacuum degas for 15 min, and coat it onto the surface of pretreated water-based polyurethane synthetic leather by scraping. The wet film thickness is 30 μm. First, pre-bake at 85℃ for 4 min, and then cure at 120℃ for 4 min. The sheet resistance of the conductive layer is measured to be 25 Ω / sq. Step 3: Take 20 parts by weight of water-soluble polyaniline dispersion (15% solid content), 65 parts of water-based polyurethane emulsion, 14 parts of deionized water, and 0.7 parts of water-based isocyanate crosslinking agent, stir evenly, and coat the surface of the water-based conductive layer by roller coating. The wet film thickness is 20 μm. Dry at 75°C for 8 min to form an electrochromic layer. Step 4: Take 55 parts by weight of 10% PVA aqueous solution (molecular weight 1700), 8 parts by weight of 5% LiCl aqueous solution, 25 parts by weight of aqueous acrylic emulsion, and 12 parts by weight of deionized water. Stir until transparent and homogeneous to form an aqueous gel electrolyte. Coat the electrolyte evenly on the surface of the electrochromic layer using a gravure coating method. The wet film thickness is 40 μm. Dry at 65℃ for 6 min. Step 5: Composite counter electrode: The aqueous conductive cloth and the aqueous gel electrolyte layer are hot-pressed together at a temperature of 80℃, a pressure of 0.3MPa, and a time of 4min to form a sandwich structure. Step 6: Water-based encapsulation and surface protection: The edges of the sandwich structure are sealed with water-based sealant with a sealing width of 1 mm. Then, a water-based transparent scratch-resistant polyurethane protective layer (25% solid content) is coated on the surface of the electrode with a wet film thickness of 25 μm. The material is then dried at 90°C for 6 min to obtain synthetic leather. Step 7: Cut the synthetic leather into 5cm × 5cm samples, and lead wires from the conductive layer and the counter electrode respectively using conductive tape. Connect the wires to a DC regulated power supply and set the voltage to 3.5V. After power is applied, the electrochromic layer changes color, but the response speed is slow, with a coloring response time of 4.2s and a fading response time of 3.9s; after 2800 cycles, a significant color difference decay occurs. A noticeable organic solvent odor is present during the preparation process.

[0047] Comparison Group 2 This comparative group provides a fully water-based electrochromic synthetic leather, comprising, from bottom to top: a water-based substrate, a water-based conductive layer, a water-based electrochromic layer, a water-based gel electrolyte layer, a counter electrode, a water-based transparent scratch-resistant protective layer, and a water-based edge encapsulation layer encapsulated on both sides of the multi-layer sandwich structure. The preparation method of this fully water-based electrochromic synthetic leather includes the following steps: Step 1: Take water-based polyurethane synthetic leather as the base, first use an oil remover to remove surface oil stains, then wipe it with a lint-free cloth to remove dust, and set aside. Step 2: Take 15 parts by weight of aqueous carbon nanotube dispersion (10% solid content), 70 parts by weight of aqueous polyurethane emulsion (30% solid content), 14 parts by weight of deionized water, and 0.3 parts by weight of aqueous leveling agent. Put them into a mixing tank and stir evenly at 300 r / min. After vacuum degassing for 15 min, apply the mixture to the surface of aqueous polyurethane synthetic leather by scraping. The wet film thickness is 30 μm. Pre-bake at 85℃ for 4 min and then cure at 120℃ for 4 min. The sheet resistance of the conductive layer is measured to be 25 Ω / sq. Step 3: Take 20 parts by weight of water-soluble polyaniline dispersion (15% solid content), 65 parts of water-based polyurethane emulsion, 14 parts of deionized water, and 0.7 parts of water-based isocyanate crosslinking agent, stir evenly, and coat the surface of the water-based conductive layer by roller coating. The wet film thickness is 20 μm. Dry at 75°C for 8 min to form an electrochromic layer. Step 4: Take 55 parts by weight of 10% PVA aqueous solution (molecular weight 1700), 8 parts by weight of 5% LiCl aqueous solution, 25 parts by weight of aqueous acrylic emulsion, and 12 parts by weight of deionized water. Stir until transparent and homogeneous to form an aqueous gel electrolyte. Coat the electrolyte evenly on the surface of the electrochromic layer using a gravure coating method. The wet film thickness is 40 μm. Dry at 65℃ for 6 min. Step 5: Composite counter electrode: The aqueous conductive cloth and the aqueous gel electrolyte layer are hot-pressed together at a temperature of 80℃, a pressure of 0.3MPa, and a time of 4min to form a sandwich structure. Step 6: Water-based encapsulation and surface protection: The edges of the sandwich structure are sealed with water-based sealant with a sealing width of 1 mm. Then, a water-based transparent scratch-resistant polyurethane protective layer (25% solid content) is coated on the electrode surface with a wet film thickness of 25 μm. After drying at 90°C for 6 min, a water-soluble water-based electrochromic synthetic leather is obtained. The adhesion between the layers of this synthetic leather and the substrate is poor. Step 7: Cut the synthetic leather into 5cm × 5cm samples, and extend wires from the water-based conductive layer and the counter electrode using conductive tape. Connect the wires to a DC regulated power supply and set the voltage to 2.1V. After power is applied, the electrochromic layer changes color, but the adhesion between the functional layers and the substrate is poor. Cracking and delamination occur after 3500 bends; the cycle life is only 3200 cycles before performance failure.

[0048] Comparison Group 3 This comparative group provides a fully water-based electrochromic synthetic leather, comprising, from bottom to top: a water-based substrate, a water-based conductive layer, a water-based electrochromic layer, a water-based gel electrolyte layer, a counter electrode, a water-based transparent scratch-resistant protective layer, and a water-based edge encapsulation layer encapsulated on both sides of the multi-layer sandwich structure. The preparation method of this fully water-based electrochromic synthetic leather includes the following steps: Step 1: Take water-based polyurethane synthetic leather as the base, first remove surface oil with degreaser, then wipe it with a lint-free cloth to remove dust, and use corona treatment to improve the surface energy of the base. The treatment power is 300W and the treatment time is 30s. Set aside. Step 2: Take 15 parts by weight of aqueous carbon nanotube dispersion (10% solid content), 70 parts by weight of aqueous polyurethane emulsion (30% solid content), 14 parts by weight of deionized water, and 0.3 parts by weight of aqueous leveling agent. Put them into a mixing tank and stir evenly at 300 r / min. After vacuum degassing for 15 min, apply the mixture to the surface of the pretreated aqueous polyurethane synthetic leather by scraping. The wet film thickness is 30 μm. First, pre-bake at 85℃ for 4 min, and then cure at 120℃ for 4 min. The sheet resistance of the conductive layer is measured to be 25 Ω / sq. Step 3: Take 20 parts by weight of water-soluble polyaniline dispersion (15% solid content), 65 parts of water-based polyurethane emulsion, and 14 parts of deionized water, stir evenly, and coat the water-based conductive layer surface by roller coating. The wet film thickness is 20 μm. Dry at 75°C for 8 min to form an electrochromic layer. Step 4: Take 55 parts by weight of 10% PVA aqueous solution (molecular weight 1700), 8 parts by weight of 5% LiCl aqueous solution, 25 parts by weight of aqueous acrylic emulsion, and 12 parts by weight of deionized water. Stir until transparent and homogeneous to form an aqueous gel electrolyte. Coat the electrolyte evenly on the surface of the electrochromic layer using a gravure coating method. The wet film thickness is 40 μm. Dry at 65℃ for 6 min. Step 5: Composite counter electrode: The aqueous conductive cloth and the aqueous gel electrolyte layer are hot-pressed together at a temperature of 80℃, a pressure of 0.3MPa, and a time of 4min to form a sandwich structure. Step 6: Seal the edges of the sandwich structure with water-based sealant with a sealing width of 1 mm, then coat the surface of the electrode with a water-based transparent scratch-resistant polyurethane protective layer (25% solid content) with a wet film thickness of 25 μm, and dry at 90℃ for 6 min to obtain water-soluble water-based electrochromic synthetic leather. Step 7: Cut the synthetic leather into 5cm × 5cm samples, and lead wires from the water-based conductive layer and the counter electrode respectively using conductive tape. Connect the wires to a DC regulated power supply and set the voltage to 2.0V. After power is applied, the electrochromic layer changes color, but it is prone to cracking. The coloring response time is 2.5s, the fading response time is 2.2s, and the color difference significantly decreases after 3800 cycles; cracks and delamination appear after 4000 bends.

[0049] Comparison Group 4 This comparative group provides a fully water-based electrochromic synthetic leather, comprising, from bottom to top: a water-based substrate, a water-based conductive layer, a water-based electrochromic layer, a water-based gel electrolyte layer, a counter electrode, a water-based transparent scratch-resistant protective layer, and a water-based edge encapsulation layer encapsulated on both sides of the multi-layer sandwich structure. The preparation method of this fully water-based electrochromic synthetic leather includes the following steps: Step 1: Take water-based polyurethane synthetic leather as the base, first remove surface oil with degreaser, then wipe it with a lint-free cloth to remove dust, and use corona treatment to improve the surface energy of the base. The treatment power is 300W and the treatment time is 30s. Set aside. Step 2: Take 15 parts by weight of aqueous carbon nanotube dispersion (10% solid content), 70 parts by weight of aqueous polyurethane emulsion (30% solid content), 14 parts by weight of deionized water, and 0.3 parts by weight of aqueous leveling agent. Put them into a mixing tank and stir evenly at 300 r / min. After vacuum degassing for 15 min, apply the mixture to the surface of the pretreated aqueous polyurethane synthetic leather by scraping. The wet film thickness is 30 μm. First, pre-bake at 85℃ for 4 min, and then cure at 120℃ for 4 min. The sheet resistance of the conductive layer is measured to be 25 Ω / sq. Step 3: Take 20 parts by weight of water-soluble polyaniline dispersion (15% solid content), 65 parts of water-based polyurethane emulsion, 14 parts of deionized water, and 0.7 parts of water-based isocyanate crosslinking agent, stir evenly, and coat the surface of the water-based conductive layer by roller coating. The wet film thickness is 20 μm. Dry at 75°C for 8 min to form an electrochromic layer. Step 4: Take 88 parts by weight of 5% LiCl aqueous solution and 12 parts by weight of deionized water, stir until transparent and homogeneous to form an aqueous gel electrolyte, and uniformly coat it on the surface of the electrochromic layer using a gravure coating method. The wet film thickness is 40 μm, and dry it at 65℃ for 6 min. Step 5: Composite counter electrode: The aqueous conductive cloth and the aqueous gel electrolyte layer are hot-pressed together at a temperature of 80℃, a pressure of 0.3MPa, and a time of 4min to form a sandwich structure. Step 6: Seal the edges of the sandwich structure with water-based sealant with a sealing width of 1 mm, then coat the surface of the electrode with a water-based transparent scratch-resistant polyurethane protective layer (25% solid content) with a wet film thickness of 25 μm, and dry at 90℃ for 6 min to obtain water-soluble water-based electrochromic synthetic leather. Step 7: Cut the synthetic leather into 5cm × 5cm samples, and lead wires from the water-based conductive layer and the counter electrode respectively using conductive tape. Connect the wires to a DC regulated power supply and set the voltage to 2.0V. After power is applied, the electrochromic layer changes color, but the electrolyte is prone to leakage, and leakage still occurs after encapsulation. The coloring response time is 3.8s, and the fading response time is 3.5s; the cycle life is only 2500 cycles, which is severely degraded; during bending resistance, electrolyte overflow occurs, causing a short circuit.

[0050] The synthesis of experimental groups 1-3 and control groups 1-4 was tested. The sheet resistivity of the conductive layer was measured using the four-probe method. The operating voltage was measured using a DC regulated power supply. The coloring response time and fading response time were measured using a spectrophotometer. Cycle life was tested using ±2V voltage cycling. Bending resistance was tested by repeated bending at R=5mm. Adhesion was tested using the cross-cut adhesion test (GB / T 9286-1998). VOC emissions were tested according to GB / T 27630-2011 standard. Hydrolysis resistance was tested at 60℃ / 90%RH for 72 hours.

[0051] Table 1. Performance parameters of synthetic leather in each experimental and control group.

[0052] According to Table 1: 1. As verified by experimental groups 1-3, the all-water-based electrochromic synthetic leather prepared by this invention can achieve low-voltage driving with a working voltage of 1.5-3V, rapid color change with a coloring and fading response time of 1-3s, a cycle life of ≥5000 times, no cracking or delamination after 10000 bends with R=5mm, adhesion of grade 0 in cross-cut adhesion test, zero VOC emissions, and excellent hydrolysis resistance (no abnormalities after 72h in a 60℃ / 90%RH environment).

[0053] 2. Compared with Group 1 (using an oily conductive bottom layer), the VOC emission was as high as 82mg / m³, the adhesion dropped to level 3, the delamination occurred after 2000 bends, the working voltage increased to 3.5V, the response time was extended to 4.2s, the cycle life was only 2800 cycles, and the hydrolysis resistance was poor (blistering after 48h). This shows that the all-water-based material system of this invention has significant advantages in terms of environmental protection, physical properties, and electrochromic properties.

[0054] 3. In contrast group 2 (without substrate pretreatment), the adhesion dropped to level 2, and cracking and delamination occurred after 3,500 bending cycles. The cycle life was only 3,200 cycles before failure, indicating that substrate pretreatment has a promoting effect on improving the bonding strength between each functional layer and the substrate.

[0055] 4. In contrast, the electrochromic layer of group 3 (without water-based crosslinking agent) was prone to cracking, with an adhesion grade of 1. Cracks and delamination occurred after 4,000 bends. The color difference significantly decreased after 3,800 cycles, and the response time was slightly prolonged. This indicates that the introduction of water-based crosslinking agent can significantly improve the density and interlayer bonding strength of the electrochromic layer, ensuring product durability.

[0056] 5. Compared with Group 4 (using liquid electrolyte), the electrolyte was prone to leakage, and leakage still occurred after encapsulation. The coloring and fading response time was extended to 3.8s / 3.5s, and the cycle life was severely reduced to only 2500 cycles. During the bending process, leakage and short circuit occurred. This shows that the use of gel electrolyte in this invention can effectively solve the problems of leakage, corrosion and poor stability of liquid electrolyte, and improve the long-term stability of the product.

[0057] In summary, the synthetic leather of this invention achieves comprehensive improvements in environmental friendliness, stability, and mass production through material and structural improvements and optimized preparation methods, and has application value.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing all-water-based electrochromic synthetic leather, characterized in that: Includes the following steps: Step 1: Degrease and remove dust from the water-based substrate, then perform corona treatment or plasma treatment; Step 2: Apply the water-based conductive paste to the pretreated surface of the water-based substrate, and then pre-bake and cure it to form a water-based conductive layer; Step 3: Coat the surface of the water-based conductive layer with the water-based electrochromic paste, and dry it to form a water-based electrochromic layer; Step 4: Coat the surface of the aqueous electrochromic layer with the aqueous gel electrolyte slurry, and dry it to form the aqueous gel electrolyte layer; Step 5: The counter electrode and the aqueous gel electrolyte layer are hot-pressed together to form a multilayer sandwich structure; Step 6: Seal the edges of the multi-layer sandwich structure with water-based sealant, then coat the electrode surface with a water-based transparent scratch-resistant polyurethane protective layer, and dry to obtain fully water-based electrochromic synthetic leather.

2. The method for preparing all-water-based electrochromic synthetic leather according to claim 1, characterized in that: In step two, the aqueous conductive layer slurry comprises, by weight, 10-30 parts of aqueous carbon nanotube dispersion or aqueous graphene dispersion, 60-80 parts of aqueous polyurethane emulsion, 10-20 parts of deionized water, and 0.2-0.5 parts of aqueous leveling agent; the coating is performed by scraping, roller coating, or gravure coating; the pre-baking temperature is 80-90℃ for 3-5 minutes, and the curing temperature is 110-130℃ for 3-5 minutes; the sheet resistivity of the aqueous conductive layer is 15-45 Ω / sq.

3. The method for preparing all-water-based electrochromic synthetic leather according to claim 1, characterized in that: In step three, the aqueous electrochromic layer slurry comprises, by mass parts: 15-25 parts of one or more of the following: water-soluble polyaniline dispersion, aqueous polythiophene dispersion, or aqueous polypyrrole dispersion; 60-75 parts of aqueous polyurethane emulsion; 10-20 parts of deionized water; and 0.5-1 parts of aqueous crosslinking agent. The wet film thickness after coating is 18-22 μm, the drying temperature is 70-80℃, and the drying time is 5-10 min. The aqueous crosslinking agent is an aqueous isocyanate crosslinking agent or an aqueous epoxy crosslinking agent.

4. The method for preparing all-water-based electrochromic synthetic leather according to claim 1, characterized in that: In step four, the aqueous gel electrolyte slurry comprises, by mass parts: 50-60 parts of an 8-12% concentration PVA aqueous solution, 5-10 parts of a lithium salt aqueous solution, 20-30 parts of an aqueous acrylic emulsion, and 10-15 parts of deionized water; the wet film thickness after coating is 35-40 μm, the drying temperature is 60-70℃, and the drying time is 5-8 min; the lithium salt aqueous solution is a LiCl aqueous solution or a LiTFSI aqueous solution with a concentration of 5-10%.

5. The method for preparing all-water-based electrochromic synthetic leather according to claim 1, characterized in that: In step five, the hot-pressing composite temperature is 70-90℃, the pressure is 0.2-0.5MPa, and the time is 3-5min; the thickness of the counter electrode is 15-25μm.

6. The method for preparing all-water-based electrochromic synthetic leather according to claim 1, characterized in that: In step six, the wet film thickness of the water-based transparent scratch-resistant polyurethane protective layer is 20-30 μm, the drying temperature is 80-100℃, and the time is 5-8 min; the thickness of the water-based edge encapsulation is 1.0-1.3 mm.

7. The method for preparing all-water-based electrochromic synthetic leather according to claim 1, characterized in that: The water-based substrate is water-based polyurethane synthetic leather or water-based microfiber leather, and the thickness of the water-based substrate is 1.0±0.1mm.

8. The method for preparing all-water-based electrochromic synthetic leather according to claim 1, characterized in that: The performance indicators of the all-water-based electrochromic synthetic leather are as follows: working voltage 1.5-3V, color change response time 1-3s, cycle life ≥5000 times, no cracking or peeling after 10000 bends with R=5mm, adhesion level 0 in cross-cut adhesion test, and zero VOC emissions.

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