Preparation method of knittable flexible piezoelectric ceramic composite fiber

Abstract

The invention relates to the field of intelligent wearable materials, and discloses a preparation method of a knittable flexible piezoelectric ceramic composite fiber. The preparation method comprises the following steps: S1, preparing a water-soluble material a and a water-soluble material b into a high-viscosity spinning solution; s2, adding lead-free piezoelectric ceramic powder into the high-viscosity fiber solution to obtain a high-viscosity mixed spinning solution; s3, dropwise adding a cross-linking agent, and stirring to obtain a nascent fiber spinning solution; s4, performing wet spinning to obtain primary piezoelectric ceramic composite fibers; s5, water washing, degumming and desalting, water immersion cleaning and drying are conducted, and the flexible piezoelectric ceramic composite fiber capable of being woven is obtained. According to the method, the flexible piezoelectric ceramic composite fiber with high flexibility, high softness and good piezoelectric property can be obtained, and the flexible piezoelectric ceramic composite fiber has extremely high self-adaptability and curved surface fitting property, can be freely bent and woven, and can be flexibly combined with various textile materials to prepare intelligent wearable products; and a stable electromechanical transformation effect is provided in an application process.

Description

Technical Field

[0001] The present invention relates to the field of intelligent wearable materials, and particularly to a preparation method of a woven flexible piezoelectric ceramic composite fiber. Background Art

[0002] As a new type of micro-intelligent technology product, intelligent wearable devices are developing rapidly and are widely used in fields such as communication, military, medical, and electromagnetic shielding. With the wide and complex use environment, the rigid structure batteries commonly used to provide power for wearable devices are difficult to meet the requirements of sustainable, highly adaptable, flexible and lightweight use, severely restricting the development of intelligent wearables and related fields. Therefore, it is of great development significance to study a new type of energy supply system.

[0003] Piezoelectric ceramics have advantages such as fast response speed and high sensitivity, and are ideal materials for converting mechanical energy into electrical energy. However, they have defects such as high brittleness and poor bendability, and cannot be applied to curved surface structures. Among the currently common polymer piezoelectric materials, such as polyvinylidene fluoride and its copolymers, although they meet the requirements of high flexibility and wearing comfort in the wearable field, they have problems such as high preparation requirements, low electromechanical conversion efficiency, and high costs. Therefore, the current mainstream solution is to combine piezoelectric ceramic particles with piezoelectric polymers, and use processes such as hot pressing or stretching to make the mixture into fibers or films, thereby enhancing their flexibility, and thus preparing materials with good piezoelectric properties and mechanical flexibility. Summary of the Invention

[0004] The present invention provides a preparation method of a woven flexible piezoelectric ceramic composite fiber. By combining lead-free piezoelectric ceramic particles with a water-soluble polymer material, a high-flow gel is formed through a coordination polymerization reaction with a weak acid cross-linking agent, and then wet spinning is used to prepare fibers. Through process adjustment and post-treatment, a flexible piezoelectric ceramic composite fiber material with high flexibility, high softness, and good piezoelectric properties can be obtained. This composite fiber material has extremely high self-adaptability and surface fittingness, can be bent arbitrarily and woven, can be flexibly combined with various textile materials to prepare lightweight, sensitive, and highly responsive intelligent wearable products, and provides a stable electromechanical conversion effect during application.

[0005] The specific technical solution of the present invention is as follows:

[0006] A preparation method of a woven flexible piezoelectric ceramic composite fiber, comprising the following steps:

[0007] S1. Dissolve water-soluble material a and water-soluble material b in water to prepare a high-viscosity spinning solution.

[0008] S2. Add the lead-free piezoelectric ceramic powder to the high-viscosity spinning solution and disperse it evenly to obtain a high-viscosity mixed spinning solution.

[0009] S3. Drop the weak acid cross-linking agent solution into the high-viscosity mixed spinning solution and stir until it becomes a highly fluid gel-like state to obtain a primary fiber spinning solution.

[0010] S4. Perform wet spinning on the primary fiber spinning solution and receive it with an alkaline solution as a coagulation bath to obtain primary piezoelectric ceramic composite fibers.

[0011] S5. Debond and desalt the primary piezoelectric ceramic composite fibers in sequence, wash them with water, and dry them to obtain braidable flexible piezoelectric ceramic composite fibers.

[0012] In the present invention, a water-soluble material is used as a flexible carrier and blended with lead-free piezoelectric ceramic powder. After forming a highly fluid gel through a coordination polymerization reaction with a weak acid cross-linking agent, wet spinning is used to prepare fibers. Through process adjustment and post-treatment, flexible piezoelectric ceramic composite fiber materials with high flexibility, high softness, and good piezoelectric properties can be obtained. This composite fiber material has extremely high self-adaptability and surface fitting properties, can be bent arbitrarily and woven, can be flexibly combined with various textile materials to prepare lightweight, sensitive, and highly responsive smart wearable products, and provides a stable electromechanical conversion effect during application.

[0013] Preferably, in S1, the water-soluble material a is selected from one or more of glycerol, 1,4-butanediol, polyethylene glycol, neopentyl glycol, 1,6-hexanediol, pentaerythritol, polyvinyl alcohol, and dipropylene glycol; the water-soluble material b is selected from one or more of polybutadiene resin, epoxy resin, acrylic resin, phenolic resin, alkyd resin, amino resin, polyurethane resin, and silicone resin.

[0014] In the present invention, two water-soluble materials with different properties are selected as the main components of the spinning solution. Among them, the main function of the water-soluble material a is to endow the high-viscosity spinning solution with high-strength viscous characteristics and promote the combination between lead-free piezoelectric ceramic powder particles through intermolecular forces; the function of the water-soluble material b is to toughen and strengthen the piezoelectric ceramic composite fibers and provide a necessary mechanical support structure for the fiber spinning and forming process. Compared with a spinning solution containing only one water-soluble material, this composite solution can not only effectively regulate the interfacial compatibility between the inorganic lead-free piezoelectric ceramic powder and the organic resin matrix, but also significantly improve the flexible characteristics and braidable processing performance of the final composite fiber product.

[0015] Most preferably, in S1, the best combination of water-soluble material a + water-soluble material b is: polyethylene glycol with a molecular weight of 120,000 + polyurethane resin; glycerol + polyurethane resin or polyvinyl alcohol with a molecular weight of 20,000 + silicone resin.

[0016] Preferably, in S1, the mass ratio of the water-soluble material a to the water-soluble material b is 8 to 20:1.

[0017] Preferably, in S1, in the high-viscosity spinning solution, the total mass concentration of the water-soluble material a and the water-soluble material b is 8 to 26 wt%.

[0018] The present invention finds that the ratio of the water-soluble material a to the water-soluble material b is crucial for the performance of the final product. When the ratio of the water-soluble material a to the water-soluble material b in the spinning solution system is too high, that is, the content of the water-soluble material b providing flexibility is too low, the flexible piezoelectric ceramic composite fiber loses its weavable characteristics; while when the ratio of the water-soluble material a to the water-soluble material b in the spinning solution system is too low, that is, the content of the water-soluble material a providing adhesive strength is too low, a stable gel system cannot be formed, and the fiber cannot be continuously extruded in the subsequent wet spinning process.

[0019] Preferably, in S2, the preferred particle size range of the lead-free piezoelectric ceramic powder is 0.05 to 0.8 mm.

[0020] The present invention finds that the particle size of the lead-free piezoelectric ceramic powder has a significant impact on the piezoelectric effect and flexibility of the final product. If the particle size of the lead-free piezoelectric ceramic powder is too low, the dispersibility of the ceramic powder in the flexible carrier is too high, the crystal structure aggregation degree of the ceramic crystal becomes low and the electromechanical conversion efficiency is reduced, and the piezoelectric effect of the prepared flexible piezoelectric ceramic composite fiber is poor; while if the particle size of the lead-free piezoelectric ceramic powder is too high, the interfacial bonding force between the large-diameter powder particles and the matrix is weak, which will cause peeling or delamination, further weakening the overall performance of the fiber, and the prepared flexible piezoelectric ceramic composite fiber loses the continuity and weavable characteristics provided by the flexible carrier.

[0021] Preferably, in S2, the addition amount of the lead-free piezoelectric ceramic powder is 0.2 to 15% of the mass of the high-viscosity spinning solution.

[0022] The present invention finds that the addition amount of the lead-free piezoelectric ceramic powder has a significant impact on the performance of the final product. If the addition amount is too low, the piezoelectric effect of the flexible piezoelectric ceramic composite fiber will be poor due to insufficient proportion of the piezoelectric phase; while if the addition amount is too high, the flexibility will be lost due to the weak interfacial bonding force between the piezoelectric phase and the flexible carrier, and the reduced fluidity of the high spinning solution further hinders the fiber forming process.

[0023] Preferably, in S2, the lead-free piezoelectric ceramic powder is selected from one or more of strontium barium niobate (BSN)-based lead-free piezoelectric ceramics, barium sodium niobate (BNN)-based lead-free piezoelectric ceramics, potassium sodium niobate (KNN)-based lead-free piezoelectric ceramics, bismuth sodium titanate (BNT)-based lead-free piezoelectric ceramics, and barium titanate (BT)-based lead-free piezoelectric ceramics.

[0024] Preferably, in S3, the addition amount of the weak acid crosslinking agent is 0.02-0.5% of the total mass of the water-soluble material a and the water-soluble material b in S1.

[0025] Preferably, in S3, the weak acid crosslinking agent is selected from one or more of carbonic acid, acetic acid, nitrous acid, boric acid, hypochlorous acid, hydrofluoric acid, picric acid, and citric acid.

[0026] Preferably, in S4, the wet spinning specifically includes: evacuating and degassing the primary fiber spinning solution, extruding it into a NaOH / ethanol coagulation bath at a temperature of 30-80°C through a steel needle at an extrusion speed of 0.1-15 mL / min at room temperature, and the receiving speed of the rotating disk receiver is 30-120 r / min.

[0027] Preferably, in S5, the temperature of degumming and desalting is 180-220°C.

[0028] Preferably, in S5, the fiber diameter of the braidable flexible piezoelectric ceramic composite fiber is 0.1-0.7 mm.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] (1) By combining lead-free piezoelectric ceramic particles with water-soluble polymer materials, the present invention uses a coordination polymerization reaction with a weak acid crosslinking agent to form a highly fluid gel and then uses wet spinning to prepare fibers. Through process adjustment and post-treatment, a flexible piezoelectric ceramic composite fiber material with high flexibility, high softness, and good piezoelectric properties can be obtained. This composite fiber material has extremely high self-adaptability and surface fittingness, can be bent arbitrarily and woven, can be flexibly combined with various textile materials to prepare lightweight, sensitive, and highly responsive smart wearable products, and provides a stable electromechanical conversion effect during application.

[0031] (2) All raw materials used in the present invention are non-toxic to the human body and the production environment. The fibers are prepared by a green and environmentally friendly wet spinning process. The process is simple and the cost is low, greatly reducing the post-treatment cost caused by hot processing and the solvent method. Description of the Drawings

[0032] Figure 1 It is a bow tie woven from the braidable flexible piezoelectric ceramic composite primary fiber and the fiber after high-temperature treatment in Example 1 (the upper right corner inset).

[0033] Figure 2 It is the test result of the piezoelectric constant after polarization treatment of the braidable flexible piezoelectric ceramic composite fiber described in Example 1;

[0034] Figure 3 It is a photo of the extremely brittle fiber material prepared in Comparative Example 2. Detailed implementation mode

[0035] The present invention will be further described below in conjunction with embodiments.

[0036] Embodiment 1

[0037] S1. Prepare the primary fiber spinning solution:

[0038] S1.1. Dissolve polyethylene glycol with a molecular weight of 1.2 million and a polyurethane resin emulsion with a solid content of 40% in ultrapure water at a mass ratio of 16:5 (i.e., the mass ratio of polyethylene glycol to polyurethane is 8:1), and use a magnetic stirrer to rapidly stir to prepare a high-viscosity spinning solution with a mass concentration of 12 wt%.

[0039] S1.2. Add lead-free piezoelectric ceramic powder: Add lead-free barium strontium titanate piezoelectric ceramic powder with a particle size of 0.2 mm to the obtained high-viscosity spinning solution, and the addition amount is 0.2% of the mass of the high-viscosity spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained.

[0040] S1.3. Add a cross-linking agent: Drop a citric acid solution with a mass of 1% of the total mass of polyethylene glycol and polyurethane resin into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution.

[0041] S2. Prepare fibers: Use wet spinning to prepare fibers. First, evacuate and defoam the spinning solution. At ambient temperature, extrude through a steel needle (16G) with an inner diameter of 1.041 mm at an extrusion speed of 5 mL / min into a NaOH / ethanol coagulation bath. The temperature of the coagulation bath is 50°C, and the receiving speed of the rotating disk receiver is 30 r / min.

[0042] S3. Post-treatment: Debond and desalt the obtained primary piezoelectric ceramic composite fibers at 200°C, wash them with ultrapure water, and dry them at room temperature to obtain braidable flexible piezoelectric ceramic composite fibers with a diameter of 0.37 mm.

[0043] The physical diagram of the primary piezoelectric ceramic composite fibers in S2 of this embodiment is as Figure 1 shown, and the morphology of the bowtie woven from the braidable flexible piezoelectric ceramic composite fibers obtained in S3 is as Figure 1 shown in the upper right inset in

[0044] Embodiment 2

[0045] S1. Prepare the primary fiber spinning solution:

[0046] S1.1. Dissolve glycerol and a polyurethane resin emulsion with a solids content of 80% in ultrapure water at a mass ratio of 44:5 (i.e., the mass ratio of glycerol to polyurethane is 11:1), and use a magnetic stirrer to rapidly stir to prepare a high-viscosity spinning solution with a mass concentration of 10 wt%.

[0047] S1.2. Add lead-free piezoelectric ceramic powder: Add lead-free sodium potassium niobate piezoelectric ceramic powder with a particle size of 0.2 mm to the obtained high-viscosity spinning solution, and the addition amount is 5% of the mass of the high-viscosity spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained.

[0048] S1.3. Add a cross-linking agent: Drop a picric acid solution with a mass of 0.3% of the total mass of glycerol and polyurethane resin into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution.

[0049] S2. Prepare fibers: Use wet spinning to prepare fibers. First, evacuate and degas the spinning solution. At ambient temperature, extrude it into a NaOH / ethanol coagulation bath through a steel needle (16G) with an inner diameter of 1.041 mm at an extrusion speed of 3 mL / min. The temperature of the coagulation bath is 70 °C, and the receiving speed of the rotating disk receiver is 50 r / min.

[0050] S3. Post-treatment: Subject the obtained as-spun piezoelectric ceramic composite fibers to degumming and desalting at 200 °C, wash them with ultrapure water, and dry them at room temperature to obtain braidable flexible piezoelectric ceramic composite fibers with a diameter of 0.63 mm.

[0051] Example 3

[0052] S1. Prepare the as-spun fiber spinning solution:

[0053] S1.1. Dissolve polyvinyl alcohol with a molecular weight of 20,000 and an organosilicon resin emulsion 9608 with a solids content of 40% in ultrapure water at a mass ratio of 24:5 (i.e., the mass ratio of polyvinyl alcohol to polyurethane is 12:1), and use a magnetic stirrer to rapidly stir to prepare a high-viscosity spinning solution with a mass concentration of 8 wt%.

[0054] S1.2. Add lead-free piezoelectric ceramic powder: Add lead-free sodium barium niobate piezoelectric ceramic powder with a particle size of 0.2 mm to the obtained high-viscosity spinning solution, and the addition amount is 9% of the mass of the obtained high-viscosity spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained.

[0055] S1.3. Add a cross-linking agent: Drop an acetic acid solution with a mass of 0.5% of the total mass of polyvinyl alcohol and organosilicon resin into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution.

[0056] S2. Preparation of fibers: The fibers are prepared by wet spinning. First, the spinning solution is evacuated and degassed. At ambient temperature, it is extruded through a steel needle (16G) with an inner diameter of 1.041 mm into a NaOH / ethanol coagulation bath at an extrusion rate of 2 mL / min. The temperature of the coagulation bath is 50 °C, and the receiving speed of the rotating disk receiver is 15 r / min;

[0057] S3. Post-treatment: The as-prepared primary piezoelectric ceramic composite fibers are degummed and desalted at 200 °C, washed with ultrapure water, and dried at room temperature to obtain braidable flexible piezoelectric ceramic composite fibers with a diameter of 0.29 mm.

[0058] Comparative Example 1 (only different from Example 3 in that the ratio of water-soluble materials a / b is too low)

[0059] S1. Preparation of the primary fiber spinning solution:

[0060] S1.1. Polyvinyl alcohol with a molecular weight of 20,000 and silicone resin emulsion 9608 with a solids content of 40% are dissolved in ultrapure water at a mass ratio of 12:5 (i.e., the mass ratio of polyvinyl alcohol to silicone resin is 6:1), and a high-viscosity spinning solution with a mass concentration of 8 wt% is prepared by rapid stirring using a magnetic stirrer;

[0061] S1.2. Addition of lead-free piezoelectric ceramic powder: Lead-free sodium barium niobate piezoelectric ceramic powder with a particle size of 0.2 mm is added to the obtained high-viscosity spinning solution in an amount of 9% of the mass of the obtained high-viscosity spinning solution, and a high-viscosity mixed spinning solution is obtained after ultrasonic treatment;

[0062] S1.3. Addition of cross-linking agent: An acetic acid solution with a content of 0.5% of the total mass of the solids of polyvinyl alcohol and silicone resin is added dropwise to the obtained high-viscosity mixed spinning solution, and it is continuously stirred at a low speed using a magnetic stirring device to obtain the required spinning solution;

[0063] S2. Preparation of fibers: The fibers are prepared by wet spinning. First, the spinning solution is evacuated and degassed. At ambient temperature, it is extruded through a steel needle (16G) with an inner diameter of 1.041 mm into a NaOH / ethanol coagulation bath at an extrusion rate of 2 mL / min. The temperature of the coagulation bath is 50 °C, and the receiving speed of the rotating disk receiver is 15 r / min; Since the spinning solution prepared in this comparative example cannot be further spun and formed due to the too low ratio of water-soluble a and water-soluble material b.

[0064] Comparative Example 2 (only different from Example 3 in that the ratio of polymer a / b is too high)

[0065] S1. Preparation of the primary fiber spinning solution:

[0066] S1.1. Dissolve polyvinyl alcohol with a molecular weight of 2w and silicone resin emulsion 9608 with a solids content of 40% in ultrapure water at a mass ratio of 10:1 (i.e., the mass ratio of polyvinyl alcohol to silicone resin is 25:1), and use a magnetic stirrer to rapidly stir to prepare a high-viscosity spinning solution with a mass concentration of 8 wt%.

[0067] S1.2. Add lead-free piezoelectric ceramic powder: Add lead-free sodium barium niobate piezoelectric ceramic powder with a particle size of 0.2 mm to the obtained high-viscosity spinning solution, and the addition amount is 9% of the mass of the obtained high-viscosity spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained.

[0068] S1.3. Add cross-linking agent: Drop acetic acid solution with a mass of 0.5% of the total mass of polyvinyl alcohol and silicone resin into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution.

[0069] S2. Prepare fibers: Use wet spinning to prepare fibers. First, evacuate and defoam the spinning solution. At ambient temperature, extrude it into a NaOH / ethanol coagulation bath through a steel needle (16G) with an inner diameter of 1.041 mm at an extrusion speed of 2 mL / min. The temperature of the coagulation bath is 50 °C, and the receiving speed of the rotating disk receiver is 15 r / min; Since the spinning solution prepared in this comparative example has too low ratios of water-soluble a and water-soluble material b, further spinning and forming cannot be carried out.

[0070] Comparative Example 3 (The difference between Comparative Example 3 and Example 3 is that it does not contain water-soluble material b)

[0071] S1. Prepare the primary fiber spinning solution:

[0072] S1.1. Dissolve polyvinyl alcohol with a molecular weight of 2w in ultrapure water, and use a magnetic stirrer to rapidly stir to prepare a high-viscosity spinning solution with a mass concentration of 8 wt%.

[0073] S1.2. Add lead-free piezoelectric ceramic powder: Add lead-free sodium barium niobate piezoelectric ceramic powder with a particle size of 0.2 mm to the obtained high-viscosity spinning solution, and the addition amount is 9% of the mass of the obtained spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained.

[0074] S1.3. Add cross-linking agent: Drop acetic acid solution with a mass of 0.5% of the mass of polyvinyl alcohol into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution.

[0075] S2. Fiber Preparation: The fiber is prepared by wet spinning. First, the spinning solution is evacuated to remove air bubbles. At ambient temperature, it is extruded through a steel needle (16G) with an inner diameter of 1.041 mm into a NaOH / ethanol coagulation bath at an extrusion rate of 2 mL / min. The temperature of the coagulation bath is 50 °C, and the receiving speed of the rotating disk receiver is 15 r / min;

[0076] S3. Post-treatment: The fibers prepared in this comparative example are not flexible and are extremely easy to break as Figure 3 shown, and the post-treatment process cannot be carried out.

[0077] Comparative Example 4 (The difference between Comparative Example 4 and Example 3 is that the particle size of the lead-free ceramic powder is too large)

[0078] S1. Preparation of Primary Fiber Spinning Solution:

[0079] S1.1. Dissolve polyvinyl alcohol with a molecular weight of 20,000 and the silicone resin emulsion 9608 with a solids content of 40% in ultrapure water at a mass ratio of 24:5 (i.e., the mass ratio of polyvinyl alcohol to silicone resin is 12:1), and use a magnetic stirrer to quickly stir to prepare a high-viscosity spinning solution with a mass concentration of 8 wt%;

[0080] S1.2. Add lead-free piezoelectric ceramic powder: Add lead-free sodium barium niobate piezoelectric ceramic powder with a particle size of 1.0 mm to the obtained high-viscosity spinning solution, and the addition amount is 9% of the mass of the obtained high-viscosity spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained;

[0081] S1.3. Add cross-linking agent: Drop acetic acid solution with a content of 0.5% of the total mass of polyvinyl alcohol and silicone resin into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution;

[0082] S2. Fiber Preparation: The fiber is prepared by wet spinning. First, the spinning solution is evacuated to remove air bubbles. At ambient temperature, it is extruded through a steel needle (16G) with an inner diameter of 1.041 mm into a NaOH / ethanol coagulation bath at an extrusion rate of 2 mL / min. The temperature of the coagulation bath is 50 °C, and the receiving speed of the rotating disk receiver is 15 r / min; Due to the too large particle size of the lead-free ceramic powder in this comparative example, continuous spinning cannot be carried out.

[0083] Comparative Example 5 (The difference between Comparative Example 5 and Example 3 is that the particle size of the lead-free ceramic powder is too small)

[0084] S1. Preparation of Primary Fiber Spinning Solution:

[0085] S1.1. Dissolve polyvinyl alcohol with a molecular weight of 2w and silicone resin emulsion 9608 with a solids content of 40% in ultrapure water at a mass ratio of 24:5 (i.e., the mass ratio of polyvinyl alcohol to silicone resin is 12:1), and use a magnetic stirrer to rapidly stir to prepare a high-viscosity spinning solution with a mass concentration of 8 wt%.

[0086] S1.2. Add lead-free piezoelectric ceramic powder: In the obtained high-viscosity spinning solution, add lead-free sodium barium niobate piezoelectric ceramic nanof powder with a particle size of 600 nm to 10 μm prepared by a jet mill, and the addition amount is 9% of the mass of the obtained spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained.

[0087] S1.3. Add cross-linking agent: Drop acetic acid solution with 0.5% of the total mass of polyvinyl alcohol and silicone resin into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution.

[0088] S2. Prepare fibers: Use wet spinning to prepare fibers. First, evacuate and defoam the spinning solution. At ambient temperature, extrude it into a NaOH / ethanol coagulation bath through a steel needle (16G) with an inner diameter of 1.041 mm at an extrusion speed of 2 mL / min. The temperature of the coagulation bath is 50 °C, and the receiving speed of the rotating disk receiver is 15 r / min.

[0089] S3. Post-treatment: Debond and desalt the obtained as-spun piezoelectric ceramic composite fibers at 200 °C, wash them with ultrapure water and dry them at room temperature to obtain a braidable flexible piezoelectric ceramic composite fiber with a diameter of 0.29 mm.

[0090] Comparative Example 6 (The difference between Comparative Example 6 and Example 3 is that the content of lead-free piezoelectric ceramic powder is too high)

[0091] S1. Prepare as-spun fiber spinning solution:

[0092] S1.1. Dissolve polyvinyl alcohol with a molecular weight of 2w and silicone resin emulsion 9608 with a solids content of 40% in ultrapure water at a mass ratio of 24:5 (i.e., the mass ratio of polyvinyl alcohol to silicone resin content is 12:1), and use a magnetic stirrer to rapidly stir to prepare a high-viscosity spinning solution with a mass concentration of 8 wt%.

[0093] S1.2. Add lead-free piezoelectric ceramic powder: In the obtained high-viscosity spinning solution, add lead-free sodium barium niobate piezoelectric ceramic nanof powder with a particle size of 0.2 mm, and the addition amount is 20% of the mass of the obtained spinning solution. After ultrasonic treatment, a high-viscosity mixed spinning solution is obtained.

[0094] S1.3. Add crosslinking agent: Drop acetic acid solution with a mass of 0.5% of the total mass of polyvinyl alcohol and silicone resin into the obtained high-viscosity mixed spinning solution, and continuously stir at a low speed with a magnetic stirring device to obtain the required spinning solution;

[0095] S2. Prepare fibers: Use wet spinning to prepare fibers. First, evacuate and defoam the spinning solution. At ambient temperature, extrude it into a NaOH / ethanol coagulation bath through a steel needle (16G) with an inner diameter of 1.041 mm at an extrusion speed of 2 mL / min. The temperature of the coagulation bath is 50 °C, and the receiving speed of the rotating disk receiver is 15 r / min; Since the content of lead-free piezoelectric ceramic powder in the spinning solution prepared in this comparative example is too high, continuous spinning cannot be carried out.

[0096] Performance testing

[0097] Conduct tensile property testing and piezoelectric property testing on the fibers obtained in the above-mentioned examples and comparative examples. The tensile property testing refers to the conditions and methods specified in GB / T 14344-2022, and the piezoelectric constant testing results are obtained through the conditions and methods specified in GB3389.4-82. The results are shown in Table 1.

[0098] Table 1 Tensile property testing and piezoelectric property testing results of the braidable flexible piezoelectric ceramic composite fibers in each case

[0099]

[0100] Note: (“—” Due to the inability to obtain continuous fiber samples in Comparative Examples 1, 2, 3, 4, and 6, the test data are missing; in Comparative Example 5, no piezoelectric test data are obtained because the ceramic piezoelectric phase does not aggregate.)

[0101] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a braidable flexible piezoelectric ceramic composite fiber, characterized in that include: S1, dissolving water-soluble material a and water-soluble material b in water to obtain a high-viscosity spinning solution; The water-soluble material a is selected from one or more of glycerol, 1,4-butanediol, polyethylene glycol, neopentyl glycol, 1,6-hexanediol, pentaerythritol, polyvinyl alcohol and dipropylene glycol; The water-soluble material b is selected from one or more of polybutadiene resin, epoxy resin, acrylic resin, phenolic resin, alkyd resin, amino resin, polyurethane resin and silicone resin; S2, adding the lead-free piezoelectric ceramic powder to the high-viscosity spinning solution and dispersing it evenly to obtain a high-viscosity mixed spinning solution; S3, adding a weak acid crosslinking agent dropwise to the high-viscosity mixed spinning solution, stirring until it becomes a high-flow gel, to obtain a primary fiber spinning solution; S4, wet spinning the nascent fiber spinning solution, using an alkaline solution as a coagulation bath to obtain nascent piezoelectric ceramic composite fibers; S5. Degumming and desalting the nascent piezoelectric ceramic composite fibers in sequence, washing with water, and drying the fibers to obtain braidable flexible piezoelectric ceramic composite fibers.

2. The preparation method according to claim 1, characterized in that In S1, the mass ratio of the water-soluble material a to the water-soluble material b is 8 to 20:

1.

3. The preparation method according to claim 1, characterized in that: In S1, in the high-viscosity spinning solution, the total mass concentration of the water-soluble material a and the water-soluble material b is 8 to 26 wt%.

4. The preparation method according to claim 1, characterized in that: In S2, The particle size of the lead-free piezoelectric ceramic powder is 0.05 to 0.8 mm; The added amount of the lead-free piezoelectric ceramic powder is 0.2-15% of the mass of the high-viscosity spinning solution.

5. The preparation method according to claim 1 or 4, characterized in that: In S2, the lead-free piezoelectric ceramic powder is selected from one or more of strontium barium niobate-based lead-free piezoelectric ceramics, barium sodium niobate-based lead-free piezoelectric ceramics, potassium sodium niobate-based lead-free piezoelectric ceramics, bismuth sodium titanate-based lead-free piezoelectric ceramics and barium titanate-based lead-free piezoelectric ceramics.

6. The preparation method according to claim 1, characterized in that: In S3, the added amount of the weak acid cross-linking agent is 0.02-0.5% of the total mass of the water-soluble material a and the water-soluble material b in S1.

7. The preparation method according to claim 1 or 6, characterized in that: In S3, the weak acid cross-linking agent is selected from one or more of carbonic acid, acetic acid, nitrous acid, boric acid, hypochlorous acid, hydrofluoric acid, lime acid and citric acid.

8. The preparation method according to claim 1, characterized in that: In S4, the wet spinning specifically includes: vacuum degassing the nascent fiber spinning solution, extruding it into a NaOH / ethanol coagulation bath through a steel needle at an extrusion speed of 0.1 to 15 mL / min at room temperature, the coagulation bath temperature is 30 to 80°C, and the receiving speed of the rotating disc receiver is 30 to 120 r / min.

9. The preparation method according to claim 1, characterized in that: In S5, the temperature of the degumming and desalting is 180-220°C.

10. The preparation method according to claim 1 or 9, characterized in that: In S5, the fiber diameter of the braidable flexible piezoelectric ceramic composite fiber is 0.1-0.7 mm.

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