Flexible conductive porous elastomer with pressure sensing function as well as preparation method and application of flexible conductive porous elastomer

Abstract

The invention provides a flexible conductive porous elastomer with a pressure sensing function as well as a preparation method and application of the flexible conductive porous elastomer, and relates to the technical field of functional sensing materials. The preparation method comprises the following steps: carrying out first mixing on an elastomer rubber material, a conductive filler and an auxiliary agent to obtain a first mixed material; performing second mixing on the first mixing material, a first template agent (water-soluble inorganic salt) and a second template agent (water-soluble polymer) to obtain a second mixing material; carrying out hot-pressing vulcanization on the second mixed material to obtain a molded part; and carrying out water washing and pore forming on the molded part, and then drying to obtain the flexible conductive porous elastomer with the pressure sensing function. The prepared flexible conductive porous elastomer with the pressure sensing function has the advantages of high sensitivity, wide detection range, good rebound resilience and high stability, so that the increasing requirements of different fields on flexible pressure sensors are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional sensing materials, in particular to a flexible conductive pressure sensing functional porous elastomer and a preparation method and application thereof. BACKGROUND

[0002] As an electronic device that can convert mechanical information into electrical signals, flexible pressure sensors have shown great application potential in many fields such as wearable electronic devices, health and sports monitoring, intelligent human-computer interaction and artificial intelligence. For example, in wearable devices, it can monitor physiological signals of the human body such as pulse, respiration, etc.; in the field of intelligent human-computer interaction, it can achieve more natural and accurate human-computer interaction experience.

[0003] Traditional methods introduce micro-pyramids, micro-columns, micro-hemispheres and interlocking microstructures into the pressure-sensitive layer of the sensor to improve sensitivity, but these microstructures are easily saturated under low pressure load, resulting in small pressure detection range, complex preparation process, high cost and difficulty in mass production. Later, conductive aerogel pressure sensing materials were developed. Although the aerogel structure constructed by conductive materials has the advantages of ultra-low density, high porosity, excellent electrical conductivity and good thermal stability, it has important value in porous electrodes, electromagnetic shielding, adsorption and other fields, but its inherent mechanical rigidity and brittleness limit its sensitivity and compression strain range, and the network structure is easily damaged irreversibly during compression, resulting in plastic deformation and irreversible change in electrical conductivity, which limits its application in the field of flexible pressure sensing.

[0004] With the rapid development of wearable electronics and portable intelligent systems, it is necessary to prepare a pressure sensing functional material with high sensitivity, wide detection range, good resilience and high stability. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a flexible conductive pressure sensing functional porous elastomer and a preparation method and application thereof. The flexible conductive pressure sensing functional porous elastomer prepared by the present application has high sensitivity, wide detection range, good resilience and high stability.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions: The present application provides a preparation method of a flexible conductive pressure sensing functional porous elastomer, comprising the following steps: mixing an elastomer compound, a conductive filler and an additive to obtain a first mixed material; the additive comprises a vulcanizing agent; mixing the first mixed material with a first template agent and a second template agent to obtain a second mixed material; the first template agent is a water-soluble inorganic salt, and the second template agent is a water-soluble polymer; The second mixed material is hot-pressed and vulcanized to obtain a molded part; The molded part is washed with water to form pores, and then dried to obtain the flexible conductive pressure sensing functional porous elastomer.

[0007] Preferably, the elastomer compound comprises one or more of polyurethane, styrene-based thermoplastic elastomer and rubber.

[0008] Preferably, the conductive filler comprises one or more of silver powder, silver-coated copper powder, conductive carbon black, carbon nanotube, graphene and nickel-coated carbon fiber.

[0009] Preferably, the water-soluble inorganic salt comprises one or more of sodium chloride, sodium sulfate and sodium carbonate; the water-soluble polymer comprises one or more of polyethylene glycol, polyethylene oxide and polyvinyl alcohol, and the weight average molecular weight of the water-soluble polymer is 8000-100000.

[0010] Preferably, the elastomer compound is 100 parts, the conductive filler is 100-800 parts, the first template agent is 50-800 parts, the second template agent is 10-300 parts, and the auxiliary agent is 1-100 parts by mass fraction.

[0011] Preferably, the temperature of the first mixing and the second mixing is independently 50-200℃, and the time is independently 20-40min.

[0012] Preferably, the temperature of the hot-pressing and vulcanization is 170℃, the pressure is 10MPa, and the time is 10min.

[0013] The present application provides a flexible conductive pressure sensing functional porous elastomer prepared by the preparation method, comprising a porous elastomer matrix and a conductive filler, the porous elastomer has an interconnected open structure, and the conductive filler is compounded in the interior of the porous elastomer matrix and the surface of the open structure.

[0014] The present application provides an application of the flexible conductive pressure sensing functional porous elastomer in an intelligent wearable device.

[0015] Preferably, the intelligent wearable device comprises intelligent shoe materials.

[0016] The present application provides a preparation method of a flexible conductive pressure sensing functional porous elastomer, which uses an elastomer compound as a matrix material and adopts a physical foaming method of a double-template method to construct a porous elastomer material. High conductive filler loading can give high conductivity to the material, but it will cause the modulus of the material to be high, making the material brittle and hard, and unable to realize the compression strain response caused by deformation; and high content of fillers will cause the material to be difficult to process, uneven mixing, and difficult to shape. The present application introduces two kinds of templates, among which the second template, i.e. water-soluble polymer, is in a molten state during processing (mixing process), which can temporarily increase the polymer ratio during the melting process to improve the loading capacity of the filler, and can be water-soluble in the subsequent water washing process; After water washing, the conductive fillers are uniformly distributed on the surface of the open structure and in the elastomer matrix to construct a perfect conductive network. This method makes the material have high conductivity while considering good flexibility. The present application realizes high compression strain through the construction of the open structure connected by the double template agent, and the directional distribution of the conductive filler and the compression strain caused by the compression deformation result in the sensing sensitivity of the compression strain. The present application can adjust the Young's modulus (hardness) of the material by selecting the type of elastomer compound, adjust the resistance range of the material by adjusting the type and amount of conductive filler, and adjust the foaming ratio of the material by adjusting the amount of template agent, so that the conductive porous elastomer material can produce resistance change response to pressure in the range of 0.05kg / cm 2 ~120kg / cm 2 , and obtain a wide detection range. The porous elastomer provided by the present application has good aging resistance (80℃ high temperature aging test for 600h in the examples), and due to the stability of the conductive filler and the good resilience of the porous elastomer, the porous elastomer has stability of conductive performance and sensing performance.

[0017] The present application provides a flexible conductive pressure sensing functional porous elastomer prepared by the preparation method described in the above technical scheme. The flexible conductive pressure sensing functional porous elastomer provided by the present application has high sensitivity, wide detection range, good resilience and high stability. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 and Figure 2 is a process flow chart for preparing the flexible conductive pressure sensing functional porous elastomer of the present application; Figure 3 is a scanning electron microscope image (left) of the flexible conductive pressure sensing functional porous elastomer prepared in Example 2, and the distribution of silver element and carbon element in the material and between the pore structures (right) at this position; Figure 4 is the resistivity test and test results of the flexible conductive pressure sensing functional porous elastomer, Figure 4 (a) is a material surface resistivity test photo, and (b) is a material overall conductivity statistical chart; Figure 5 Pressure sensing function test process and results of flexible conductive pressure sensing function porous elastomer prepared for Example 4, Figure 5 (a) is fixed weight porous elastomer compression, (b) is the rebound after the porous elastomer is released, and (c) is the relative resistance change curve during compression-release; Figure 6 Cyclic compression test results of flexible conductive pressure sensing function porous elastomer prepared for Example 5 before and after 600h oven high temperature aging at 80℃; Figure 7 Cyclic compression resistance test results of flexible conductive pressure sensing function porous elastomer prepared for Example 5; Figure 8 The hardness of the porous elastomer material obtained after adjusting the elastomer base material ratio, foaming ratio, and type and ratio of fillers; Figure 9 Sensing of the flexible conductive pressure sensing function porous elastomer material to the foot landing posture and the perception signal (△R / R0 refers to the relative resistance change) of the foot arch state, Figure 9 In the figure, a is a human running schematic diagram; b is the change of the resistance signal generated by the material of the foot arch when the rear foot lands on the ground during running; c is the change of the resistance signal generated by the material when the foot sole lands during running; d is the change of the resistance signal generated by the material when the front foot sole lands during running; e is (i) rear landing, (ii) full landing, and (iii) front landing posture; f is the rear view, side view, and bottom view of the normal foot arch form; g is the resistance change generated by the material when the normal arch rises and collapses; h is the calf posture corresponding to the normal foot arch posture and the leg shape change caused by foot arch collapse; Figure 10 Structure schematic diagram of intelligent shoe material, Figure 10 In the figure, 1 and 3 are packaging materials, 2 is a shoe pad, and 4 is a sensor unit prepared from a flexible conductive pressure sensing function porous elastomer. DETAILED DESCRIPTION

[0019] The present application provides a preparation method of a flexible conductive pressure sensing function porous elastomer, comprising the following steps: The elastomer compound, conductive filler, and auxiliary agent are first mixed to obtain a first mixed material; the auxiliary agent includes a vulcanizing agent; The first mixed material, a first template agent, and a second template agent are second mixed to obtain a second mixed material; the first template agent is a water-soluble inorganic salt, and the second template agent is a water-soluble polymer; The second mixed material is hot-pressed and vulcanized to obtain a molded part; The shaped piece is washed with water to form pores, and then dried to obtain the flexible conductive pressure sensing functional porous elastomer.

[0020] Figure 1 and Figure 2 A process flow chart for preparing the flexible conductive pressure sensing functional porous elastomer according to the embodiments of the present application is shown in FIG. 1. The embodiments of the present application will be described in detail below with reference to FIG. 1. Figure 1 and Figure 2

[0021] In the present application, the raw materials involved are all commercially available products well known in the art, unless otherwise specified.

[0022] In the present application, the elastomer compound, the conductive filler and the auxiliary agent are first mixed to obtain a first mixed material.

[0023] In the present application, the elastomer compound preferably comprises one or more of polyurethane, styrene-based thermoplastic elastomer (TPS) and rubber; the polyurethane can be mixing type polyurethane (MPU) and / or thermoplastic polyurethane (TPU), the styrene-based thermoplastic elastomer can be SEBS (styrene-ethylene-butylene-styrene block copolymer), and the rubber can be silicone rubber, natural rubber or synthetic rubber. In the present application, the conductive filler preferably comprises one or more of silver powder, silver-coated copper powder, conductive carbon black, carbon nanotube (CNT), graphene and nickel-coated carbon fiber, and the conductive carbon black can be Ketjen black (such as Ketjen Black EC300J, 600JD). The conductive filler can adopt various morphologies of the above fillers, such as spherical silver powder and / or flaky silver powder. In the present application, the auxiliary agent comprises a vulcanizing agent, and the present application does not have any particular requirement for the vulcanizing agent, which can be any vulcanizing agent well known to those skilled in the art, such as peroxide or crosslinking agent. In the present application, the auxiliary agent can further comprise an antioxidant, and the present application does not have any particular requirement for the antioxidant, which can be any antioxidant well known to those skilled in the art.

[0024] In the present application, the elastomer compound is preferably pre-mixed, and the conductive filler and the auxiliary agent are sequentially added to the pre-mixed elastomer compound to perform the first mixing.

[0025] ​In the present application, the pre-mixing method is preferably internal mixing, two-roll mixing, extrusion or kneading, and the pre-mixing temperature is preferably 50-200℃. When the elastomer compound is a styrene-based thermoplastic elastomer, the pre-mixing method is preferably internal mixing, and the pre-mixing temperature is preferably 100℃, and the pre-mixing time is preferably 30min. When the elastomer compound is polyurethane or rubber, the pre-mixing method is preferably two-roll mixing, and the pre-mixing temperature of polyurethane is preferably 60℃, and the pre-mixing temperature of rubber is preferably 25℃ (room temperature); in the two-roll mixing, the speed difference of the two rolls is preferably set to be 2rpm or more, and the rolling times of the compound are preferably 6-8 times.

[0026] In the present application, the first mixing temperature is preferably 50-200℃, more preferably the same as the pre-mixing temperature; the first mixing time is preferably 20-40min, and the first mixing time is calculated from the completion of the addition of the additives.

[0027] For different types of elastomer compounds or different types of conductive fillers, the formula should be appropriately adjusted according to the density of the material, the suitable processing temperature of the material, the suitable processing method, etc. to obtain the expected performance. For example, the density of polyurethane is higher than that of silicone rubber and styrene-based thermoplastic elastomer (such as SEBS), so the mass ratio should be increased in the actual processing process, and the processing temperature also needs to be adjusted: polyurethane is 60℃, rubber is room temperature, and styrene-based thermoplastic elastomer is 100℃.

[0028] After obtaining the first mixing material, the first mixing material is mixed with the first template agent and the second template agent to obtain a second mixing material.

[0029] In the present application, the water-soluble inorganic salt preferably includes one or more of sodium chloride, sodium sulfate and sodium carbonate; the water-soluble polymer preferably includes one or more of polyethylene glycol (PEG), polyethylene oxide and polyvinyl alcohol, and the weight average molecular weight of the water-soluble polymer is preferably 8000-100000.

[0030] In the present application, the mass fraction of the elastomer compound is preferably 100 parts, the mass fraction of the conductive filler is preferably 100-800 parts, the mass fraction of the first template agent is preferably 50-800 parts, the mass fraction of the second template agent is preferably 10-300 parts, and the mass fraction of the auxiliary agent is preferably 1-100 parts. In the present application, the mass fraction of the conductive filler can be 150, 200, 250, 260, 300, 330, 360, 380, 400, 420, 500, 600, 700 or 800 parts, the mass fraction of the first template agent can be 100, 200, 300, 400, 500, 600, 700 or 800 parts, the mass fraction of the second template agent can be 15, 20, 50, 100, 200 or 300 parts, and the mass fraction of the auxiliary agent can be 2, 10, 20 or 50 parts.

[0031] In the present application, the temperature of the second mixing is preferably 50-200℃, and the time is preferably 20-40 min; the temperature of the first mixing and the second mixing is preferably the same.

[0032] The present application adopts the above mixing sequence, which can fully mix the conductive filler and the elastomer compound (the mixing time of the conductive filler is the longest), and ensure uniform dispersion.

[0033] After obtaining the second mixed material, the present application performs hot press vulcanization on the second mixed material to obtain a molded part (containing the template agent).

[0034] In the present application, the temperature of the hot press vulcanization is preferably 170℃, the pressure is preferably 10 MPa, and the time is preferably 10 min. In the present application, the specific operation of the hot press vulcanization is preferably as follows: the second mixed material is placed in a mold frame, and then placed in a press to perform hot press (or mold press) vulcanization at the temperature and pressure; after the hot press vulcanization, cold press shaping is performed.

[0035] After obtaining the molded part, the present application performs water washing to form pores on the molded part, and then performs drying to obtain the flexible and conductive pressure sensing functional porous elastomer.

[0036] The present application preferably soaks the molded part in water to perform water washing to form pores, and the soaking time is preferably 24 h. In the soaking process, the water solubility of the first template agent and the second template agent is eliminated, and a porous elastomer is formed.

[0037] High content of conductive filler loading can give the material high electrical conductivity, but will cause the material modulus to be high, making the material brittle and hard, unable to realize the compression strain response caused by deformation; and high content of filler will cause the material to be difficult to process, mixing is uneven, and it is difficult to form. The present application introduces two kinds of templates, among which the second template, i.e. water-soluble polymer, is in a molten state during processing (heat is also generated during the mixing process), and the viscosity is significantly lower than that of the polymer (i.e. elastomer compound) melt. During processing and mixing, a part of the conductive filler will be mixed in the second template melt, increasing the loading capacity of the filler. During the subsequent water washing process, the second template will dissolve and precipitate in water, forming cavities in the material. However, the conductive filler will not be precipitated and will remain on the surface of the pore structure. The directional migration of the conductive filler to the surface of the open pore structure, as well as the uniform distribution of the conductive filler in the elastomer matrix, constructs a perfect conductive network. The present application uses water-soluble inorganic salt template as a pore-forming agent, and water-soluble polymer template as a temporary compatibilizer and second template pore-forming agent. The present application solves the contradiction between high electrical conductivity and material flexibility by using a double template physical foaming method. This method can also achieve open-cell foaming under high filler loading, which cannot be achieved by conventional physical and chemical foaming processes.

[0038] In the present application, the temperature of drying is preferably 60℃, and the drying is preferably carried out in an oven.

[0039] The preparation method provided by the present application can prepare a flexible conductive pressure sensing functional porous elastomer with high sensitivity, high stability, wide detection range, good resilience and customizable properties, thereby meeting the growing demand for flexible pressure sensors in different fields, while reducing production costs and realizing mass production. In addition, the preparation method provided by the present application is universal for elastomer materials and can be applied to various types of conductive fillers and general / high-performance elastomers / rubbers.

[0040] The present application provides a flexible conductive pressure sensing functional porous elastomer prepared by the preparation method described in the above technical solution, which comprises a porous elastomer matrix and a conductive filler. The porous elastomer has an interconnected open-cell structure, and the conductive filler is compounded in the interior of the porous elastomer matrix and on the surface of the open-cell structure.

[0041] In the present application, the directional migration of the conductive filler to the surface of the open-cell structure, as well as the uniform distribution of the conductive filler in the elastomer matrix and the construction of a perfect conductive network, make the porous elastomer material have high electrical conductivity while considering the flexibility of the material, and have excellent pressure sensing effect. Moreover, the pressure sensing functional porous elastomer provided by the present application is a vulcanized rubber material, which can withstand high temperature process treatment, such as a processing temperature of 140℃ for shoe materials.

[0042] The application provides application of the flexible conductive pressure sensing functional porous elastomer in an intelligent wearable device.

[0043] In the application, the intelligent wearable device preferably comprises intelligent shoe materials, for example, the flexible conductive pressure sensing functional porous elastomer is made into a sensor unit and is embedded on components such as a shoe pad, a vamp and a sole, so that the pressure distribution of the sole can be accurately reflected by combining a circuit design and a signal processing system.

[0044] In order to further illustrate the application, the flexible conductive pressure sensing functional porous elastomer provided by the application, a preparation method and application thereof are described in detail below with reference to examples, but they should not be understood as limiting the protection scope of the application.

[0045] Example 1 Preparation of the flexible conductive pressure sensing functional porous elastomer (a flowchart is shown in Figure 1 The following is a specific description: 15 g of a styrene thermoplastic elastomer (SEBS) is added to a 100℃ internal mixer and is mixed for 30 min, 20 g of high-conductivity carbon black (Ketjen Black EC300J) and 20 g of carbon nanotubes (CNT) are added in batches, and after uniform mixing (20 min), 1.5 g of a vulcanizing agent (bis-dipentyl) is added and is mixed for 20 min, then 60 g of a template agent (NaCl) and 3 g of polyethylene glycol (PEG, weight average molecular weight 20000) are added and are uniformly mixed (0.5 h), to obtain a raw material. A certain amount of the raw material is placed in a mold frame, and then is placed in a 170℃ press at a pressure of 10 MPa and is molded for 10 min, then is cold-pressed and is shaped, the obtained sample is placed in water for desalination for 24 h, is washed with water, and is dried in an oven at 60℃ to obtain a final product. A thin sheet-shaped sample with a final thickness of 0.4 mm or less is obtained, and then is subjected to the next step of molding processing.

[0046] Example 2 Preparation of the flexible conductive pressure sensing functional porous elastomer (a flowchart is shown in Figure 1 The following is a specific description: Put 20 g of mixed polyurethane (MPU) on a 60 °C double roller for 30 min, the double roller speed is 9 rpm and 11 rpm respectively, roll the rubber 6-8 times, add spherical silver powder and flaky silver powder 25 g each, mix evenly (10-12 times, about 1 h) after adding vulcanizing agent double two five 2 g, mix evenly (0.5 h) after adding template agent NaCl (100 g) and polyethylene glycol (PEG, weight average molecular weight 20000) 3 g, to obtain the raw material. Put a certain mass of raw material in the mold frame, then put it in the 170 °C press under the pressure of 10 MPa for 10 min, then cold-pressing shaping, put the obtained sample in water for 24 h, then wash with water and dry in the oven at 60 °C to obtain the final product. Obtain the final thickness of the sheet-shaped sample below 0.4 mm, then proceed to the next step of forming processing.

[0047] Example 3 Preparation of flexible conductive pressure sensing functional porous elastomer (flow as shown in Figure 1 The specific steps are as follows: Put 15 g of mixed silicone rubber on a double roller for room temperature mixing, the double roller speed is 9 rpm and 11 rpm respectively, roll the rubber 6-8 times, add silver-coated copper powder 40 g, mix evenly (10-12 times, about 1 h) after adding vulcanizing agent double two five 1.5 g, mix evenly (0.5 h) after adding template agent NaCl 60 g and polyethylene glycol (PEG, weight average molecular weight 20000) 3 g, to obtain the raw material. Put a certain mass of raw material in the mold frame, then put it in the 170 °C press under the pressure of 10 MPa for 10 min, then cold-pressing shaping, put the obtained sample in water for 24 h, then wash with water and dry in the oven at 60 °C to obtain the final product. Obtain the final thickness of the sheet-shaped sample below 0.4 mm, then proceed to the next step of forming processing.

[0048] Example 4 Replace the conductive filler in Example 1 with spherical silver powder and flaky silver powder 27 g each, 28.5 g each, 30 g each, and 31.5 g each respectively, and the rest is the same as Example 1.

[0049] Example 5 Replace the conductive filler in Example 1 with spherical silver powder and flaky silver powder 25 g each, and the rest is the same as Example 1.

[0050] The raw material formula and vulcanization process conditions of the flexible conductive pressure sensing functional porous elastomer prepared in the example are listed in Table 1.

[0051] Table 1 Raw material formula and vulcanization process conditions in the example

[0052] The flexible conductive pressure sensing functional porous elastomer prepared in the examples was structurally characterized and performance tested, as follows: (I) Structural characterization Figure 3 The cross-sectional scanning electron microscope image of the flexible conductive pressure sensing functional porous elastomer prepared in Example 2 (left) and the distribution of silver and carbon elements in the material and between the pore structures at this position (right). Through the cooperation of the two-component silver powder (spherical silver powder and flaky silver powder) conductive filler and the directional migration of the filler to the surface of the open pore structure during the processing, as well as the uniform distribution of the conductive filler in the elastomer matrix and the construction of a perfect conductive network, the material has high electrical conductivity while considering flexibility.

[0053] (II) Electrical conductivity of the conductive elastomer material Figure 4 The resistivity test of the flexible conductive pressure sensing functional porous elastomer prepared in Example 4 and the test results are as follows: Figure 4 Figure (a) is a photograph of the surface resistivity test of the material, and figure (b) is a statistical diagram of the overall electrical conductivity of the material. In figure (b), the horizontal coordinates 3.6, 3.8, 4, and 4.2 are the mass ratios of the filler and the polymer matrix. MPU-A represents the sample obtained by adding only conductive filler without foaming treatment in Example 2 (i.e., omitting the addition of NaCl, polyethylene glycol, and water washing to form pores in Example 2).

[0054] The electrical conductivity of the material designed in this example can reach 1.34 x 10 7 S / m, and the electrical conductivity of the material with high flexibility can reach 4.37 x 10 6 S / m. The high flexibility is achieved by using an elastomer matrix and the directional distribution of the filler at the pore edge rather than in the matrix. The electrical conductivity of the material can be adjusted from low to high, and by replacing the appropriate filler, a larger adjustment range can be obtained according to the actual use scenario. For example, under high pressure load (60 kg / cm 2 ), a high multiple of filler is needed to provide high pressure resistance and a more perfect single-point network to prevent excessive damage under high pressure. Under lower load (e.g., 6 kg / cm 2 ), the pressure of the material is small and does not require a large amount of filler to provide support, while a higher sensitivity is required, which can reduce the amount of filler, reduce the density of the conductive filler network, and reduce the overall hardness of the material, thereby increasing the degree of deformation under the same pressure, thereby intensifying the reconstruction of the conductive network under force.

[0055] (III) Flexible conductive pressure sensing function The flexible conductive pressure sensing functional porous elastomer prepared in Example 4 (30 g of spherical silver powder and 30 g of flaky silver powder) was tested for pressure sensing function: The resistance of the material has a rapid increase after a certain weight of weight is placed on the surface of the material, and returns to the original level after it is removed, as shown in Figure 5 . Figure 5 The pressure sensing function (or compression sensing function) test process and results of the flexible conductive pressure sensing functional porous elastomer prepared in Example 4, Figure 5 (a) is the compression of the porous elastomer with a fixed weight (1 kg), (b) is the rebound after the release of the porous elastomer, and (c) is the relative change curve of the resistance during compression and release, wherein ΔR / R0 in (c) refers to the relative resistance change rate, and the change rate is about 2.31%.

[0056] Pressure distribution range and application: By adjusting the Young's modulus (hardness) of the material, the resistance range of the material, and the combination of the conductive filler, the conductive elastomer material can produce resistance change response to pressure in the range of 0.05 kg / cm 2 ~120kg / cm 2 .

[0057] (Four) Durability and aging resistance of the material Figure 6 The cyclic compression test results of the flexible conductive pressure sensing functional porous elastomer prepared in Example 5 before and after high-temperature aging in an 80°C oven for 600 hours.

[0058] The porous elastomer material is tested by cyclic compression before and after high-temperature aging in an 80°C oven, and the performance after aging test does not deteriorate obviously, proving that the material has good aging resistance.

[0059] Durability range: normal use under compression ratio 0~85% compression environment, and maintaining elasticity and conductivity under-50°C~120°C environment.

[0060] (Five) Durability of electrical properties under continuous compression Figure 7 The cyclic compression resistance test results of the flexible conductive pressure sensing functional porous elastomer prepared in Example 5.

[0061] The porous elastomer material is placed in the middle of the compression clamp of the universal material compressor, with a speed of 50 mm / min and a compression stroke of 50% of the material thickness, and is subjected to reciprocating cyclic compression and measured by a digital source table. The resistance change trend and change ratio remain stable after 3000 compressions, proving the stability of the material's conductivity and sensing performance.

[0062] (Six) Softness of the flexible conductive material Figure 8After adjusting the proportion of elastomer base material, the proportion of foaming, and the type and proportion of filler, the hardness of the obtained porous elastomer material is in the range of 17-100 degrees (Shore A hardness). Figure 8 The raw material compositions of the materials corresponding to the abscissa are shown in Table 2. The preparation methods of the materials in Table 2 are the same as those in Example 1, except that the preparation method of the material "silicone rubber + conductive filler" is the same as that in Example 3.

[0063] Table 2 Figure 8 Raw material compositions of the materials corresponding to the abscissa

[0064] Note: SPF-SEBS-A4.0 in Table 2 corresponds to "4.0 times" in the abscissa, Figure 8 SPF-SEBS-A3.8 corresponds to "3.8 times" in the abscissa, Figure 8 SPF-SEBS-A3.6 corresponds to "3.6 times" in the abscissa. Figure 8 SPF-SEBS-A3.4 corresponds to "3.4 times" in the abscissa.

[0065] (Seven) Intelligent function of the material - intelligent flexible pressure sensing on the sole (1) Flexible conductive transmission: placing the flexible conductive pressure sensing functional porous elastomer prepared in the example at the arch of the foot, the instep, and the heel can monitor the state distribution of the arch collapse and the force distribution on the sole. Placing the conductive porous elastomer at the forefoot and the heel can monitor the landing posture according to the resistance change curve.

[0066] (2) Figure 9 The flexible conductive pressure sensing functional porous elastomer material senses the landing posture on the sole and perceives the signal of the arch state (△R / R0 refers to the relative resistance change). Figure 9 A comprehensive intelligent arch sensor is shown, which is used for static and dynamic combination of arch movement posture and movement correction, Figure 9 , a is a human running schematic diagram; b is the change of the resistance signal generated by the material of the arch when the rear foot lands on the ground during running; c is the change of the resistance signal generated by the material when the foot lands on the ground during running; d is the change of the resistance signal generated by the material when the forefoot lands on the ground during running; e is the (i) rear bottom, (ii) full bottom, and (iii) front bottom landing posture; f is the rear view, side view, and bottom view of the normal arch form; g is the resistance change generated by the material when the normal arch is raised and collapsed; h is the calf posture corresponding to the normal arch posture and the leg shape change caused by arch collapse.

[0067] (3) Pressure distribution: as shown in Figure 10 , the sensor unit 4 prepared by the flexible conductive pressure sensing functional porous elastomer is embedded in the insoleFigure 10 The sensor array is encapsulated by encapsulating material (such as silicone rubber material, etc.) on the surface of the middle 2), upper, sole and other components, Figure 10 The prepared sensor array is encapsulated by encapsulating material (such as silicone rubber material, etc.) on the surface of the middle 1 and 3), and the sensor array combined with circuit design and signal processing system can accurately reflect the pressure distribution of the foot bottom.

[0068] The above only describes the preferred embodiments of the present application, and does not limit the present application in any form. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A method for preparing a flexible conductive pressure sensing functional porous elastomer, characterized by, The method comprises the following steps: firstly mixing an elastomer compound, a conductive filler and an additive to obtain a first mixed material; the additive comprises a vulcanizing agent; secondly mixing the first mixed material, a first template agent and a second template agent to obtain a second mixed material; the first template agent is a water-soluble inorganic salt, and the second template agent is a water-soluble polymer; hot-press vulcanizing the second mixed material to obtain a molded piece; washing the molded piece to form pores, and then drying to obtain the flexible conductive pressure-sensing functional porous elastomer.

2. The production method according to claim 1, characterized by, The elastomer compound comprises one or more of polyurethane, styrene-based thermoplastic elastomer and rubber.

3. The preparation method according to claim 1, characterized in that, The conductive filler comprises one or more of silver powder, silver-coated copper powder, conductive carbon black, carbon nanotube, graphene and nickel-coated carbon fiber.

4. The method of claim 1, wherein, The water-soluble inorganic salt comprises one or more of sodium chloride, sodium sulfate and sodium carbonate; the water-soluble polymer comprises one or more of polyethylene glycol, polyethylene oxide and polyvinyl alcohol, and the weight average molecular weight of the water-soluble polymer is 8000-100000.

5. The method according to any one of claims 1 to 4, wherein the compound of formula (I) is prepared by the process of claim 4. The elastomer compound is 100 parts, the conductive filler is 100-800 parts, the first template agent is 50-800 parts, the second template agent is 10-300 parts, and the additive is 1-100 parts, all in terms of mass fraction.

6. The method of claim 1, wherein, The temperature of the first mixing and the second mixing is independently 50-200℃, and the time is independently 20-40 min.

7. The preparation method according to claim 1, characterized in that, The temperature of the hot-press vulcanization is 170℃, the pressure is 10 MPa, and the time is 10 min.

8. The flexible conductive pressure-sensing functional porous elastomer prepared by the method of any one of claims 1-7, comprising a porous elastomer matrix and a conductive filler, the porous elastomer has an open-pore structure, and the conductive filler is compounded in the interior of the porous elastomer matrix and on the surface of the open-pore structure.

9. The flexible conductive pressure-sensing functional porous elastomer of claim 8 in the application of a smart wearable device.

10. Use according to claim 9, characterized in that, The smart wearable device comprises smart shoe material.

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