A polyurethane composite, a pressure sensor and a preparation method and application thereof

Abstract

The application discloses a polyurethane composite material, a pressure sensor and a preparation method and application thereof, and relates to the technical field of pressure sensors.The polyurethane composite material comprises a polyurethane electrostatic spinning film layer, a first polyurethane porous film layer arranged on the upper surface of the polyurethane electrostatic spinning film layer, and a second polyurethane porous film layer arranged on the upper surface of the first polyurethane porous film layer; and the pore diameter and pore density of the first polyurethane porous film layer are greater than or smaller than the pore diameter and pore density of the second polyurethane porous film layer.In the polyurethane composite material, the polyurethane electrostatic spinning film layer has higher sensitivity and good elasticity, can quickly respond to slight pressure changes, and the first polyurethane porous film layer and the second polyurethane porous film layer can be deformed greatly under stress, thereby combining with the polyurethane electrostatic spinning film and making the conductive network in the polyurethane composite material system more abundant.

Description

Technical Field

[0001] This invention relates to the field of pressure sensor technology, and in particular to a polyurethane composite material, a pressure sensor, its preparation method, and its application. Background Technology

[0002] Porous conductive polymer composites (CPCs) are a class of materials with special structures and properties, often used in the manufacture of pressure sensors due to their excellent flexibility and high sensitivity. Pressure sensors are devices that convert changes in external pressure into electrical signals, and are widely used in industrial control, medical equipment, and intelligent electronic devices.

[0003] Constructing three-dimensional (3D) porous structures within CPCs has become a research hotspot in recent years. This structure not only effectively reduces the percolation threshold of conductive fillers and improves sensor sensitivity, but also significantly reduces material weight and enhances its compressibility. The design of 3D porous structures allows CPCs to better adapt to complex environmental changes and pressure applications, thereby expanding their practicality and stability in various applications.

[0004] Traditional pressure sensors often suffer from drawbacks such as slow response time, insufficient sensitivity, and poor adaptability to environmental changes. By adjusting the microstructure of the conductive layer in CPCs, the sensor's sensitivity and response speed can be significantly improved, enabling it to capture pressure changes more quickly and accurately. Furthermore, the hierarchical microstructure design effectively reduces the response hysteresis of flexible pressure sensors, further enhancing their reliability and stability in practical applications.

[0005] Flexible resistive sensors (CPCs) are a common application, using conductive layers (CPCs) to convert the pressure signal into a resistance signal. By precisely controlling the structure and materials of the conductive layer, the sensitivity of the resistive sensor can be accurately adjusted to meet the accuracy and response speed requirements of different applications. This highly adjustable characteristic gives CPCs a significant advantage in developing customized pressure sensors.

[0006] With the increasing demand for sensor technology, existing technologies have used a mixture of PU foam and graphene oxide to prepare a CPCs material that can be used for compression flexible strain sensing. This resistive flexible sensor features low density, excellent compressibility, and high sensitivity. However, the CPCs material has significant internal energy dissipation, leading to a lag in the sensor's signal response. Furthermore, sensors made from existing CPCs materials generally suffer from drawbacks such as high cost and complex fabrication processes.

[0007] Therefore, there is an urgent need to develop a new type of CPCs material and pressure sensor to solve the shortcomings of sensors such as signal response lag, high cost, and complex preparation process. Summary of the Invention

[0008] The purpose of this invention is to develop a novel CPCs material and pressure sensor to overcome the shortcomings of sensors such as slow signal response, high cost, and complex manufacturing process.

[0009] The first aspect of the present invention is:

[0010] A polyurethane composite material is provided.

[0011] The second aspect of the present invention is:

[0012] A method for preparing a polyurethane composite material is provided.

[0013] The third aspect of the present invention is:

[0014] Application of the polyurethane composite material.

[0015] The present invention also proposes a pressure sensor.

[0016] Specifically, the technical solution adopted according to the first aspect of the present invention is as follows:

[0017] A polyurethane composite material, the polyurethane composite material comprising:

[0018] Polyurethane electrospun film layer;

[0019] A first polyurethane porous membrane layer is disposed on the upper surface of the polyurethane electrospun membrane layer;

[0020] The second polyurethane porous membrane layer is disposed on the upper surface of the first polyurethane porous membrane layer;

[0021] The pore size and pore density of the first polyurethane porous membrane are greater than or less than the pore size and pore density of the second polyurethane porous membrane.

[0022] According to embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0023] In the polyurethane composite material of the present invention, the polyurethane electrospun film layer has higher sensitivity and better elasticity, and can respond quickly to small pressure changes. The first polyurethane porous film layer and the second polyurethane porous film layer can undergo large deformation under stress. Combined with the polyurethane electrospun film, the conductive network in the polyurethane composite material system is richer, and the response to external stimuli of different degrees is more sensitive and wider. That is, the polyurethane electrospun film layer, the first polyurethane porous film layer and the second polyurethane porous film layer can work together to achieve high sensitivity and wide response.

[0024] In the polyurethane composite material of the present invention, the pore size and pore density of the first polyurethane porous membrane layer are greater than or less than the pore size and pore density of the second polyurethane porous membrane layer, thereby making the pore size and pore density of the polyurethane composite material of the present invention have a gradient. In the polyurethane composite material, if the pore size increases stepwise from the inside to the outside, the signal can be amplified in an infinitely large manner. If the pore size decreases stepwise, the signal will be weakened.

[0025] According to one embodiment of the present invention, the raw materials of the first polyurethane porous membrane layer and the second polyurethane porous membrane layer include the following components:

[0026] Polyurethane resin;

[0027] Conductive filler;

[0028] Sacrificial materials;

[0029] Curing agent.

[0030] According to one embodiment of the present invention, the raw materials of the first polyurethane porous membrane layer and the second polyurethane porous membrane layer comprise the following components in parts by weight:

[0031] Polyurethane resin, 12-15 parts;

[0032] Conductive filler, 1-10 parts;

[0033] Sacrificial materials, 42-45 pieces;

[0034] Hardener, 2-3 parts.

[0035] According to one embodiment of the present invention, the pore size in the first polyurethane porous membrane layer and the second polyurethane porous membrane layer is 158μm-324μm.

[0036] According to one embodiment of the present invention, the pore density of the first polyurethane porous membrane layer and the second polyurethane porous membrane layer is 14.30 pores / cm². 3 -312.15 pieces / cm 3 .

[0037] According to one embodiment of the present invention, the polyurethane composite material of the present invention is a "sandwich" structure composite material, wherein the innermost layer is a polyurethane electrospun film layer, and the outer two layers are a first polyurethane porous film layer and a second polyurethane porous film layer.

[0038] According to one embodiment of the present invention, the pore size and pore density of the first polyurethane porous membrane layer and the second polyurethane porous membrane layer can be gradient-controlled according to different effects, so as to realize stepless control of the sensitivity and response range of the sensor.

[0039] This invention can adjust the pore structure of materials by controlling the preparation process of the first and second polyurethane porous membranes. Specifically, the pore size can be adjusted by adjusting the particle size of the sacrificial material, and the pore density can be adjusted by adjusting the amount of sacrificial material.

[0040] According to one embodiment of the present invention, the polyurethane composite material of the present invention has at least the following effects: (1) When subjected to a small pressure, the polyurethane electrospun film layer can respond quickly to small pressure changes, and the pressure effect can be slightly amplified by the first polyurethane porous film layer and the second polyurethane porous film layer, so as to better monitor pressure changes; (2) When subjected to a large pressure, the polyurethane porous film can undergo relatively large deformation, which can absorb external impacts and vibrations, thereby enhancing the durability and reliability of the sensor.

[0041] According to one embodiment of the present invention, when the polyurethane composite material of the present invention is used as a functional clothing material, the innermost polyurethane electrospun film layer is close to the skin layer because the polyurethane electrospun film layer has higher sensitivity and good elasticity, and can respond quickly to small pressure changes. Compared with the polyurethane porous film layer, it is more suitable to be close to the skin.

[0042] Specifically, the technical solution adopted according to the second aspect of the present invention is as follows:

[0043] A method for preparing the polyurethane composite material includes the following steps:

[0044] S1 mixes polyurethane resin and conductive filler in a solvent to obtain a spinning solution, which is then electrospun to obtain a polyurethane electrospun film.

[0045] S2 mixes polyurethane resin, conductive filler, sacrificial material and curing agent in solvent to obtain a mixed solution, and then sequentially performs leveling film formation and sacrificial material removal treatment to obtain a first polyurethane porous membrane;

[0046] S3 mixes polyurethane resin, conductive filler, sacrificial material and curing agent in solvent to obtain a mixed solution, and then sequentially performs leveling film formation and sacrificial material removal treatment to obtain a second polyurethane porous membrane;

[0047] S4 The polyurethane electrospun membrane, the first polyurethane porous membrane and the second polyurethane porous membrane are stacked sequentially and immersed in a solution containing conductive filler in a vacuum environment, and then removed to obtain the polyurethane composite material.

[0048] According to embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0049] This invention allows for the adjustment of the pore structure of the material by controlling the preparation process of the first and second polyurethane porous membranes. Secondly, the addition of conductive fillers significantly improves the electronic conductivity of the composite material. This excellent electronic conductivity enables the composite material to respond quickly and effectively to changes in electronic signals or potential caused by changes in the external environment. Furthermore, the polyurethane electrospun membrane prepared by electrospinning technology is characterized by its fineness and large surface area, which enhances the material's contact with the external environment, thereby improving the sensor's ability to detect environmental changes. Finally, in step S4, immersing the composite material in a vacuum environment ensures that the conductive filler is uniformly penetrated throughout the entire material structure, thus guaranteeing the stability and consistency of the internal conductivity of the composite material.

[0050] According to one embodiment of the present invention, in step S1, the mass percentage of polyurethane resin in the spinning solution is 15-20%.

[0051] According to one embodiment of the present invention, in step S1, the parameters of the electrospinning include: a sample injection rate of 1.0-1.2 ml / h, a collection rate of 100-120 rpm / min, and a humidity of 85-90%.

[0052] According to one embodiment of the present invention, step S2 further includes the following step: after the mixed solution is subjected to leveling and film-forming treatment to obtain a film material, the film material is first subjected to stretching and curing treatment before the sacrificial material is removed.

[0053] According to one embodiment of the present invention, in step S2, it is necessary to stir thoroughly during the dissolution of polyurethane resin to ensure that the polyurethane resin can be completely dissolved. This is because if the viscosity of the mixture is too viscous, it will lead to an increase in the modulus of the membrane and a decrease in sensitivity; if the viscosity of the mixture is too thin, it will lead to high liquid fluidity, making the membrane easy to tear and difficult to form.

[0054] Another aspect of the present invention provides a pressure sensor comprising a polyurethane composite material as described in the first aspect embodiment above. Since this application utilizes all the technical solutions described above using the polyurethane composite material, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0055] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0056] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0057] Figure 1 This is a flowchart of the preparation of polyurethane composite material in Example 1. Detailed Implementation

[0058] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0059] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the embodiments, and are only for the purpose of facilitating the description of this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0060] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0061] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0062] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of the present invention.

[0063] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0064] Example 1

[0065] A polyurethane composite material, comprising:

[0066] Polyurethane electrospun film layer;

[0067] A first polyurethane porous membrane layer is disposed on the upper surface of the aforementioned polyurethane electrospun membrane layer.

[0068] The second polyurethane porous membrane layer is disposed on the upper surface of the first polyurethane porous membrane layer.

[0069] The interlayer spacing between the polyurethane electrospun film layer and the first polyurethane porous film layer is 500 μm;

[0070] The interlayer spacing between the first polyurethane porous membrane layer and the second polyurethane porous membrane layer is 900 μm;

[0071] The first polyurethane porous membrane layer has a pore size of 202 μm and a pore density of 135.11 pores / cm³. 3 ;

[0072] The second polyurethane porous membrane has a pore size of 240 μm and a pore density of 96.97 pores / cm³. 3 .

[0073] The process for preparing the above-mentioned polyurethane composite material is shown in the flowchart below. Figure 1 As shown, specifically, it includes the following steps:

[0074] S1 mixed polyurethane resin and 1.2g carbon nanotubes in N,N-dimethylacetamide to obtain a spinning solution with a polyurethane resin mass percentage of 15%. The solution was electrospun to obtain a polyurethane electrospun membrane. The electrospinning parameters were: sample injection rate of 1.0ml / h, collection rate of 100rpm / min, voltage of 27kV, humidity of 90%, and temperature of room temperature.

[0075] S2 mixes 12g of polyurethane resin, 1.2g of carbon nanotubes, 42g of salt and 2.4g of curing agent HK-825 in N,N-dimethylformamide to obtain a mixed solution. A 10*10cm polytetrafluoroethylene plate is used as a template, and the mixed solution is evenly spread on the top of the plate. After vertical static placement and micro-wind-assisted leveling, a membrane material is obtained. The membrane material is pre-stretched to 5% using a stretching support, and then cured in a forced-air oven at 80℃ for 2 hours to obtain a pre-stretched membrane material. The pre-stretched membrane material is immersed in 80℃ circulating water for about 4 hours until no salt particles are precipitated in the washing liquid, thus obtaining the first polyurethane porous membrane.

[0076] S3 mixes 12g of polyurethane resin, 1.2g of carbon nanotubes, 42g of salt, and 2.4g of curing agent HK-825 in N,N-dimethylformamide to obtain a mixed solution. A 10*10cm polytetrafluoroethylene plate is used as a template, and the mixed solution is evenly spread on the top of the plate. After vertical static placement and micro-wind-assisted leveling, a membrane material is obtained. The membrane material is pre-stretched using a stretching support and then cured in a forced-air oven at 80℃ for 2 hours to obtain a pre-stretched membrane material. The pre-stretched membrane material is then immersed in 80℃ circulating water for about 4 hours until no salt particles precipitate out of the washing liquid, thus obtaining the second polyurethane porous membrane.

[0077] S4 The above-mentioned polyurethane electrospun membrane, the above-mentioned first polyurethane porous membrane and the above-mentioned second polyurethane porous membrane are stacked sequentially and immersed in a carbon nanotube-containing solution in a vacuum environment, and then removed to obtain the above-mentioned polyurethane composite material; wherein, the preparation step of the carbon nanotube-containing solution is as follows: using 10 mg / mL sodium dodecylbenzenesulfonate as a surfactant, carbon nanotubes are added to it, and ultrasonic dispersion is performed at a low temperature of 10°C to obtain a carbon nanotube-containing solution with a carbon nanotube concentration of 1 mg / mL.

[0078] Example 2

[0079] The difference between Example 2 and Example 1 is that in step S4 of Example 2, the concentration of carbon nanotubes in the carbon nanotube-containing solution is 0.01 mg / mL.

[0080] Example 3

[0081] The difference between Example 3 and Example 1 is that in step S4 of Example 2, the concentration of carbon nanotubes in the carbon nanotube-containing solution is 0.1 mg / mL.

[0082] Example 4

[0083] The difference between Example 4 and Example 3 is that in Example 4, the carbon nanotube solution is replaced with a graphene oxide solution.

[0084] Comparative Example 1

[0085] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 is a polyurethane material, which only has a polyurethane electrospun film layer.

[0086] Comparative Example 2

[0087] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 is a polyurethane material, which has only a first polyurethane porous membrane layer.

[0088] Performance testing:

[0089] The polyurethane materials prepared in Example 1 and Comparative Examples 1-2 were subjected to performance tests, and the test results are shown in Table 1.

[0090] Among them, tensile strain and relative resistance change were tested using a flexible electronic tester.

[0091] The flexible electronics test parameters are set as follows: clamping at both ends for 1cm, measuring length for 2cm, stretching length for 5mm, stretching rate for 1mm / s, and stretching times for 10 times.

[0092] The sensitivity of a porous polyurethane pressure sensor is expressed using the strain coefficient (GF) of a strain-type flexible sensor, defined as the ratio of the relative resistance change (R - R0 / R0) to the tensile strain (L - L0) / L0.

[0093]

[0094] R0 — Resistance value (Ω) of the porous polyurethane pressure sensor in its initial state;

[0095] R—Real-time resistance value (Ω) of the porous polyurethane pressure sensor under tensile deformation;

[0096] L0 — Length of the porous polyurethane pressure sensor in its initial state (mm);

[0097] L – The real-time length (mm) of the porous polyurethane pressure sensor under tensile deformation.

[0098] Table 1

[0099]

[0100] Comparative Example 2, lacking the structure of the polyurethane electrospun film layer, the first polyurethane porous film layer, and the second polyurethane porous film layer of the present invention, exhibits a lower sensitivity specification factor at 0-15% strain. Comparative Example 1, containing only a polyurethane electrospun film layer and lacking a polyurethane porous film layer, has a higher sensitivity specification factor for its polyurethane material compared to Example 1. However, the response range of the polyurethane material in Comparative Example 1 is worse than that in Example 1. This is because Example 1 also contains the first and second polyurethane porous film layers, which can undergo large deformations under stress. Combined with the polyurethane electrospun film, this results in a richer conductive network within the polyurethane composite material system, leading to a more sensitive and wider-range response to different levels of external stimuli. In other words, the polyurethane electrospun film layer, the first polyurethane porous film layer, and the second polyurethane porous film layer can synergistically achieve high sensitivity and a wide response range.

[0101] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A polyurethane composite material, characterized in that: The polyurethane composite material includes: Polyurethane electrospun film layer; A first polyurethane porous membrane layer is disposed on the upper surface of the polyurethane electrospun membrane layer; The second polyurethane porous membrane layer is disposed on the upper surface of the first polyurethane porous membrane layer; The pore size and pore density of the first polyurethane porous membrane are greater than or less than the pore size and pore density of the second polyurethane porous membrane. The raw materials for the first and second polyurethane porous membrane layers comprise the following components in parts by weight: Polyurethane resin, 12-15 parts; Conductive filler, 1-10 parts; Sacrificial materials, 42-45 pieces; Hardener, 2-3 parts; The pore size in the first polyurethane porous membrane layer and the second polyurethane porous membrane layer is 158μm-324μm; The pore density of the first and second polyurethane porous membrane layers is 14.30 pores / cm². 3 -312.15 pieces / cm 3 ; The polyurethane composite material is immersed in a solution containing conductive filler in a vacuum environment, and the conductive filler penetrates into the entire structure of the polyurethane composite material.

2. A method for preparing a polyurethane composite material as described in claim 1, characterized in that: Includes the following steps: S1: Mix polyurethane resin and conductive filler in a solvent to obtain a spinning solution, and then electrospin to obtain the polyurethane electrospun film layer. S2: Mix polyurethane resin, conductive filler, sacrificial material and curing agent in a solvent to obtain a mixed solution, and then successively perform leveling film formation and sacrificial material removal treatment to obtain the first polyurethane porous film layer; S3: Mix polyurethane resin, conductive filler, sacrificial material and curing agent in solvent to obtain mixed solution, and then successively perform leveling film formation and sacrificial material removal treatment to obtain the second polyurethane porous film layer; S4: The polyurethane electrospun film layer, the first polyurethane porous film layer and the second polyurethane porous film layer are stacked sequentially, and then immersed in a solution containing conductive filler in a vacuum environment. After removal, the polyurethane composite material is obtained.

3. The method according to claim 2, characterized in that: In step S1, the mass percentage of polyurethane resin in the spinning solution is 15-20%.

4. The method according to claim 2, characterized in that: In step S1, the parameters of the electrospinning include: a sample injection rate of 1.0-1.2 ml / h, a collection rate of 100-120 rpm, and a humidity of 85-90%.

5. The method according to claim 2, characterized in that: Step S2 also includes the following steps: after the mixed solution is leveled and film-forming to obtain a film material, the film material is first stretched and cured before the sacrificial material is removed.

6. A pressure sensor, characterized in that: Including the polyurethane composite material as described in claim 1.

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