A polyurethane / carbon black / Cu composite conductive fiber and its preparation method and application

Abstract

The present invention relates to the technical field of functional fiber preparation, and particularly relates to a polyurethane / carbon black / Cu composite conductive fiber, a preparation method thereof and an application. The preparation method of the polyurethane / carbon black / Cu composite conductive fiber comprises: mixing flaky copper powder with a conductive fiber spinning solution of polyurethane and carbon black to obtain a polyurethane / carbon black / Cu composite conductive fiber spinning solution; wherein, the flaky copper powder accounts for 2.5% to 20% of the mass of the polyurethane / carbon black / Cu composite conductive fiber spinning solution; and subjecting the polyurethane / carbon black / Cu composite conductive fiber spinning solution to wet spinning to obtain the polyurethane / carbon black / Cu composite conductive fiber. The preparation method of the present invention not only successfully reduces the viscosity of the TPU / CB / Cu composite conductive fiber spinning solution, solves the problems of spinneret needle blockage and complex spinning operation, but also significantly improves the conductive performance of the TPU / CB / Cu composite conductive fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of functional fiber preparation, and particularly relates to a polyurethane / carbon black / Cu composite conductive fiber, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, with the rapid progress of technology and the continuous improvement of people's living standards, consumers' demands have quietly shifted from traditional durability, fashion, and convenience to intelligent textiles that integrate self-power generation, electromagnetic protection, motion tracking, and wearable electrothermal health care functions. Driven by this trend, wearable flexible strain sensors have become a research hotspot in the fields of sports health monitoring, virtual reality experience, and human motion capture due to their unique ability to accurately convert the subtle deformation of fibers or yarns into electrical signals and instantaneously collect and analyze data through Bluetooth technology, attracting the attention and exploration of many scholars.

[0003] Currently, the wet spinning technology exhibits advantages such as simple process, excellent production efficiency, and significant cost-effectiveness in the preparation of carbon black-based conductive fibers. However, in order to endow the conductive fibers with more excellent electrical conductivity, it is usually necessary to mix a higher concentration of conductive fillers into the elastic matrix. Although this method is effective, it is also accompanied by a series of challenges: the excessive addition of conductive materials significantly increases the viscosity of the spinning solution, which not only easily causes the problem of clogging of the spinning needles, but also exacerbates the complexity of the spinning operation and energy consumption. More importantly, the sharp increase in the viscosity of the spinning solution seriously hinders the uniform mixing of the spinning solution and the uniform dispersion of conductive particles in the pre-spinning treatment stage. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a polyurethane / carbon black / Cu composite conductive fiber, a preparation method thereof, and an application thereof. The present invention adds flaky copper powder to the conductive fiber spinning solution of polyurethane and carbon black to obtain a polyurethane / carbon black / Cu composite conductive fiber spinning solution, and uses the wet spinning technology to prepare a polyurethane / carbon black / Cu composite conductive fiber. The preparation method of the present invention not only successfully reduces the viscosity of the polyurethane / carbon black / Cu composite conductive fiber spinning solution, solves the problems of spinning needle clogging and complex spinning operation, but also significantly improves the electrical conductivity of the polyurethane / carbon black / Cu composite conductive fiber.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The first object of the present invention is to provide a preparation method of a polyurethane / carbon black / Cu composite conductive fiber, comprising the following steps:

[0007] The flaky copper powder is mixed with the conductive fiber spinning solution of polyurethane and carbon black to obtain a polyurethane / carbon black / Cu composite conductive fiber spinning solution; wherein, the flaky copper powder accounts for 2.5% - 20% of the mass of the polyurethane / carbon black / Cu composite conductive fiber spinning solution; when the content of the flaky copper powder is lower than 2.5%, the viscosity of the polyurethane / carbon black / Cu composite conductive fiber spinning solution is high, and the spinning resistance of the polyurethane / carbon black / Cu composite conductive fiber spinning solution is large; when the content of the flaky copper powder is higher than 20%, the viscosity reduction effect of the flaky copper powder on the conductive fiber spinning solution of polyurethane and carbon black almost disappears, resulting in the easy breakage of the polyurethane / carbon black / Cu composite conductive fiber.

[0008] The polyurethane / carbon black / Cu composite conductive fiber spinning solution is spun by wet spinning to obtain a polyurethane / carbon black / Cu composite conductive fiber; wherein, the addition of the flaky copper powder converts the sliding friction between particles in the conductive fiber spinning solution of polyurethane and carbon black into rolling friction, reduces the viscosity of the conductive fiber spinning solution of polyurethane and carbon black, and at the same time connects the carbon black in the conductive fiber spinning solution of polyurethane and carbon black, enhancing the establishment of the electron transport channel.

[0009] Preferably, the polyurethane / carbon black conductive fiber spinning solution is prepared by the following method:

[0010] The polyurethane is dissolved in a solvent to prepare a polyurethane spinning solution with a mass fraction of 15%; the 15% polyurethane spinning solution is mixed with carbon black to obtain a polyurethane / carbon black conductive fiber spinning solution.

[0011] Preferably, in the polyurethane / carbon black conductive fiber spinning solution, the mass of the carbon black accounts for 5% - 40% of the mass of the polyurethane in the 15% polyurethane spinning solution.

[0012] Preferably, in the preparation of the polyurethane / carbon black / Cu composite conductive fiber spinning solution, the mixing method is ultrasonic; and the mixing conditions are: ultrasonic for 8h - 20h at 40°C - 60°C.

[0013] Preferably, the operation of wet spinning is: the polyurethane / carbon black / Cu composite conductive fiber spinning solution is subjected to wet drawing treatment to obtain a polyurethane / carbon black / Cu composite conductive fiber; and the conditions of the wet drawing treatment are: drawing is carried out under the condition that the extrusion rate is 40 mL / min - 120 mL / min, and the draw ratio is 1.2 - 2.0.

[0014] Preferably, after the polyurethane / carbon black / Cu composite conductive fiber spinning solution is subjected to wet drawing treatment, it is also necessary to soak in water for 1h - 8h to allow the solvent to fully diffuse; then it is dried at 40°C - 60°C for 12h - 36h to remove the residual solvent in the polyurethane / carbon black / Cu composite conductive fiber.

[0015] Preferably, in the preparation of the polyurethane / carbon black conductive fiber spinning solution, the conditions for the mixing treatment are: stirring at 40 °C to 60 °C for 10 h to 36 h.

[0016] Preferably, the solvent is selected from one or two of N,N-dimethylformamide and dimethyl sulfoxide.

[0017] The second object of the present invention is to provide a polyurethane / carbon black / Cu composite conductive fiber prepared by the above preparation method.

[0018] The third object of the present invention is to provide the application of the above polyurethane / carbon black / Cu composite conductive fiber in the preparation of fabrics.

[0019] Preferably, the application method is: combining two polyurethane / carbon black / Cu composite conductive fibers into one weft yarn, using 20 / 2 polyester sewing thread as the warp yarn, and interweaving them to form a plain fabric.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The present invention provides a preparation method of a polyurethane / carbon black / Cu composite conductive fiber. The polyurethane / carbon black / Cu composite conductive fiber is named TPU / CB / Cu composite conductive fiber, the conductive fiber spinning solution of polyurethane and carbon black is named polyurethane / carbon black conductive fiber spinning solution, and the polyurethane / carbon black conductive fiber is named TPU / CB conductive fiber; ultrasonic mixing is carried out on flaky copper powder and the TPU / CB conductive fiber spinning solution to obtain a TPU / CB / Cu composite conductive fiber spinning solution with uniform dispersion and no agglomeration precipitation; the flaky copper powder accounts for 2.5% to 20% of the mass of the polyurethane / carbon black / Cu composite conductive fiber spinning solution; wet spinning is carried out on the TPU / CB / Cu composite conductive fiber spinning solution to obtain a TPU / CB / Cu composite conductive fiber with uniform size, highly uniform dispersion of carbon black, and stable structure; among them, the introduction of flaky copper powder not only significantly reduces the viscosity of the TPU / CB / Cu composite conductive fiber spinning solution, but also establishes more conductive network paths inside the TPU / CB / Cu composite conductive fiber, greatly improving the elasticity and conductivity of the TPU / CB / Cu composite conductive fiber. The preparation method of the present invention not only successfully reduces the viscosity of the TPU / CB / Cu composite conductive fiber spinning solution, solves the problems of spinneret needle blockage and complex spinning operation, but also significantly improves the conductive performance of the TPU / CB / Cu composite conductive fiber.

[0022] 2. The present invention provides a TPU / CB / Cu composite conductive fiber, which has excellent electrical conductivity. Due to the synergistic effect between carbon black and flaky copper powder, a denser conductive path is established inside the TPU / CB / Cu composite conductive fiber, resulting in a relatively high electrical conductivity of 56.4 S / m, which is significantly better than many reported carbon black-based flexible and stretchable conductive fibers. In addition, the TPU / CB / Cu composite conductive fiber has good mechanical properties and strength, far exceeding similar products on the current market. During the stretching process, new conductive connections can be established between the carbon black and flaky copper powder inside the TPU / CB / Cu composite conductive fiber, ensuring that the TPU / CB / Cu composite conductive fiber can still maintain good electrical conductivity in the deformed state. At the same time, since the carbon black and flaky copper powder are tightly bound by the fiber network, the shedding of the carbon black and flaky copper powder is effectively prevented, thereby endowing the TPU / CB / Cu composite conductive fiber with excellent durability and stability.

[0023] 3. The present invention also applies the TPU / CB / Cu composite conductive fiber to the preparation of an interwoven plain fabric. The TPU / CB / Cu composite conductive fiber can be used as a wearable sensor to monitor human movement changes in real time, and the prepared interwoven plain fabric is used as a health electric heater, which has the advantages of mild temperature rise and protecting the human body from being scalded. Description of the Drawings

[0024] Figure 1 In the figure, a is the shear viscosity of the prepared TPU / CB conductive fiber spinning solution varying with the shear rate, and b is the optical diagram of the prepared TPU / CB conductive fiber spinning solution.

[0025] Figure 2 In the figure, a is the viscosity-shear rate curve of the prepared TPU / CB / Cu composite conductive fiber spinning solution; b is the viscosity comparison diagram of the prepared TPU / CB / Cu composite conductive fiber spinning solution at a shear rate of 0.1 rad / s.

[0026] Figure 3 This is the wet spinning process flow chart of the TPU / CB / Cu composite conductive fiber of the present invention.

[0027] Figure 4 In the figure, a is the electron microscope image of carbon black, b is the electron microscope image of flaky copper powder, c is the electron microscope image of the TPU / CB / Cu composite conductive fiber of Example 1, d is the distribution diagram of C element, and e is the distribution diagram of Cu element.

[0028] Figure 5Ultra-depth-of-field optical images of the TPU / CB conductive fibers with different carbon black contents prepared for this invention and the TPU / CB / Cu composite conductive fibers of Examples 1 to 6. Among them, a is 15% PU, b is 5% CB, c is 10% CB, d is 20% CB, e is 30% CB, f is 35% CB, g is 40% CB, h is 2.5% Cu, i is 5% Cu, j is 7.5% Cu, k is 15% Cu, l is 20% Cu.

[0029] Figure 6 Longitudinal ultra-depth-of-field optical image and bent and knotted ultra-depth-of-field optical image of the TPU / CB / Cu composite conductive fiber of Example 4 of this invention. Among them, a is the longitudinal ultra-depth-of-field optical image of the TPU / CB / Cu composite conductive fiber of Example 4, b is the bent and knotted ultra-depth-of-field optical image of the TPU / CB / Cu composite conductive fiber of Example 4, c is the physical optical image of the TPU / CB / Cu composite conductive fiber of Example 4 wound on a roller, d is the optical image and ultra-depth-of-field partial enlarged image of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber of Example 4.

[0030] Figure 7 Among them, a is the tensile stress-strain curve graph of the TPU / CB conductive fiber prepared for this invention, b is the resistance-tensile strain curve of the TPU / CB conductive fiber prepared for this invention, c is the conductivity graph of the TPU / CB conductive fiber prepared for this invention, d is the tensile stress-strain curve graph of the TPU / CB / Cu composite conductive fibers of Examples 1 to 6, e is the resistance-tensile strain curve of the TPU / CB / Cu composite conductive fibers of Examples 1 to 6, f is the conductivity graph of the TPU / CB / Cu composite conductive fibers of Examples 1 to 6.

[0031] Figure 8 Among them, a is the schematic diagram of the distribution of internal conductive particles during the drawing of the TPU / CB conductive fiber prepared for this invention, b is the schematic diagram of the distribution of internal conductive particles before and after drawing of the TPU / CB / Cu composite conductive fibers of Examples 1 to 6.

[0032] Figure 9 Graph of the rate of change of resistance when the TPU / CB conductive fiber prepared for this invention and the TPU / CB / Cu composite conductive fibers of Examples 1 to 6 are stretched at the same stretching rate and with a fixed deformation of 10%. Among them, a is 30% CB, b is 35% CB, c is 40% CB, d is 2.5% Cu, e is 5% Cu, f is 7.5% Cu, h is 15% Cu, i is 20% Cu.

[0033] Figure 10It is a test result graph of the electrical fatigue stability performance of the TPU / CB / Cu composite conductive fiber in Example 4. a is a graph of the resistance change performance of the TPU / CB / Cu composite conductive fiber in Example 4 at different stretching speeds. b is a graph of the resistance change performance of the TPU / CB / Cu composite conductive fiber in Example 4 under different stretching deformations. c is a graph of the resistance change of the TPU / CB / Cu composite conductive fiber in Example 4 in different bending states. d is a graph of the resistance change after cyclic washing and drying of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4. e is a graph of the performance of the strain sensor made of the TPU / CB / Cu composite conductive fiber in Example 4 under cyclic tensile loading and unloading > 10,000 times.

[0034] Figure 11 It is a schematic diagram of the strain sensor made of the TPU / CB / Cu composite conductive fiber in Example 4 attached to different parts for detecting human movement.

[0035] Figure 12 It is a graph of the electrothermal performance of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4. Among them, a is a comparison graph of the air permeability of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4 with different ordinary fabrics. b is a comparison graph of the moisture permeability of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4 with different ordinary fabrics. c is an optical graph of the water contact angle of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4 at different times.

[0036] Figure 13 It is a graph of the surface temperature change curve of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4 under different voltages.

[0037] Figure 14 It is a graph of the relationship between the surface temperature and the applied voltage of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4.

[0038] Figure 15 It is an infrared thermal imaging graph of the surface temperature change of the plain woven fabric made of the TPU / CB / Cu composite conductive fiber in Example 4 under different voltages. Detailed implementation manners

[0039] Next, the technical solutions of the present invention will be clearly and completely described in combination with the data in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0040] In the prior art, in order to endow conductive fibers with more excellent electrical conductivity, it is usually necessary to mix a higher concentration of conductive fillers into the elastic matrix. However, the excessive addition of conductive materials significantly increases the viscosity of the spinning solution, which not only easily causes the problem of clogging of the spinning needle, but also exacerbates the complexity and energy consumption of the spinning operation. More importantly, the sharp increase in the viscosity of the spinning solution seriously hinders the uniform mixing of the spinning solution and the uniform dispersion of conductive particles in the pre-spinning treatment stage.

[0041] Aiming at the problems existing in the prior art, the present invention provides a method for preparing a polyurethane / carbon black / Cu composite conductive fiber, comprising the following steps: mixing flaky copper powder with a conductive fiber spinning solution of polyurethane and carbon black to obtain a polyurethane / carbon black / Cu composite conductive fiber spinning solution; wherein, the flaky copper powder accounts for 2.5% to 20% of the mass of the polyurethane / carbon black / Cu composite conductive fiber spinning solution; subjecting the polyurethane / carbon black / Cu composite conductive fiber spinning solution to wet spinning to obtain a polyurethane / carbon black / Cu composite conductive fiber; wherein, the addition of flaky copper powder changes the sliding friction between particles in the conductive fiber spinning solution of polyurethane and carbon black into rolling friction, reduces the viscosity of the conductive fiber spinning solution of polyurethane and carbon black, and at the same time connects the independently distributed carbon black in the conductive fiber spinning solution of polyurethane and carbon black, enhancing the establishment of an electron transport channel.

[0042] Among them, the introduction of flaky copper powder not only significantly reduces the viscosity of the TPU / CB / Cu composite conductive fiber spinning solution, but also establishes more conductive network paths inside the TPU / CB / Cu composite conductive fiber, greatly enhancing the elasticity and conductivity of the TPU / CB / Cu composite conductive fiber. The preparation method of the present invention not only successfully reduces the viscosity of the TPU / CB / Cu composite conductive fiber spinning solution, solves the problems of spinning needle clogging and complex spinning operation, but also significantly improves the conductive performance of the TPU / CB / Cu composite conductive fiber.

[0043] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0044] Select polyurethane / carbon black - 35%, TPU / CB - 35% and prepare according to the following steps:

[0045] First, add N,N-dimethylformamide and polyurethane to a reagent bottle, heat and stir at 60°C for 2 h to completely and uniformly dissolve it, and prepare a polyurethane spinning solution with a mass fraction of 15%.

[0046] Then, weigh 15% polyurethane spinning solution by mass fraction, and add carbon black equivalent to 35% of the mass of TPU particles to the 15% polyurethane spinning solution by mass fraction. Heat and stir at 50 °C for 24 h to uniformly disperse the carbon black in the 15% polyurethane spinning solution by mass fraction, obtaining a TPU / CB conductive fiber spinning solution, denoted as polyurethane / carbon black - 35%.

[0047] Name the polyurethane / carbon black - 35% as CB - 35% conductive fiber spinning solution, prepare a TPU / CB / Cu composite conductive fiber spinning solution using the CB - 35% conductive fiber spinning solution as the substrate, and screen the addition amount of flaky copper powder. Among them, the wet spinning process flow chart of the TPU / CB / Cu composite conductive fiber is as Figure 3 shown.

[0048] Example 1

[0049] The preparation of a TPU / CB / Cu composite conductive fiber includes the following steps:

[0050] S1. Add 2.5% flaky copper powder to the CB - 35% conductive fiber spinning solution, heat and stir at 50 °C for 12 h, then sonicate for 2 h, and then put the reagent bottle back into the 50 °C magnetic stirring water bath to heat and stir for 12 h to uniformly disperse the flaky copper powder in the TPU / CB conductive fiber spinning solution, obtaining a TPU / CB / Cu - 2.5% composite conductive fiber spinning solution.

[0051] S2. Preparation of the TPU / CB / Cu composite conductive fiber:

[0052] Use a 10 mL syringe to suck up the TPU / CB / Cu - 2.5% spinning solution, adjust the extrusion rate to 80 mL / min with a 22G needle, inject the TPU / CB / Cu - 2.5% spinning solution into the deionized water coagulation bath for wet drawing and then collect it through a collecting roller. After soaking in deionized water for 8 h, dry it at 60 °C for 24 h to obtain the TPU / CB / Cu - 2.5% composite conductive fiber, denoted as 2.5% Cu.

[0053] Example 2

[0054] A preparation method of a TPU / CB / Cu composite conductive fiber is the same as the preparation steps of Example 1, except that the addition amount of flaky copper powder in S1 is 5%, obtaining a TPU / CB / Cu - 5% composite conductive fiber, denoted as 5% Cu.

[0055] Example 3

[0056] A preparation method of TPU / CB / Cu composite conductive fiber is the same as the preparation steps of Example 1, except that the addition amount of flaky copper powder in S1 is 7.5%, and the TPU / CB / Cu-7.5% composite conductive fiber is obtained, denoted as 7.5% Cu.

[0057] Example 4

[0058] A preparation method of TPU / CB / Cu composite conductive fiber is the same as the preparation steps of Example 1, except that the addition amount of flaky copper powder in S1 is 10%, and the TPU / CB / Cu-10% composite conductive fiber is obtained, denoted as 10% Cu.

[0059] Example 5

[0060] A preparation method of TPU / CB / Cu composite conductive fiber is the same as the preparation steps of Example 1, except that the addition amount of flaky copper powder in S1 is 15%, and the TPU / CB / Cu-15% composite conductive fiber is obtained, denoted as 15% Cu.

[0061] Example 6

[0062] A preparation method of TPU / CB / Cu composite conductive fiber is the same as the preparation steps of Example 1, except that the addition amount of flaky copper powder in S1 is 20%, and the TPU / CB / Cu-20% composite conductive fiber is obtained, denoted as 20% Cu.

[0063] In order to investigate the influence of the addition amount of carbon black on the spinning solution of TPU / CB conductive fiber, the addition amount of carbon black was screened, as shown in the following technical solutions:

[0064] First, add N,N-dimethylformamide and polyurethane into a reagent bottle, heat and stir at 60 °C for 2 h to completely and uniformly dissolve them, and prepare a polyurethane spinning solution with a mass fraction of 15%.

[0065] Then, weigh the polyurethane spinning solution with a mass fraction of 15%, and add carbon black equivalent to 5%, 10%, 20%, 30%, 35%, 40% of the mass of polyurethane into the polyurethane spinning solution with a mass fraction of 15% respectively, heat and stir at 50 °C for 24 h to uniformly disperse the carbon black in the polyurethane spinning solution with a mass fraction of 15%, and obtain a polyurethane / carbon black conductive fiber spinning solution, that is, TPU / CB conductive fiber, denoted as PU15%, CB-5%, CB-10%, CB-20%, CB-30%, CB-35%, CB-40% respectively.

[0066] Example 7

[0067] The preparation of a TPU / CB / Cu composite conductive fiber spin is the same as the preparation steps of Example 1, except that the CB-35% conductive fiber spinning solution in step S1 is replaced with a CB-30% conductive fiber spinning solution to obtain the TPU / CB / Cu composite conductive fiber.

[0068] Example 8

[0069] The preparation of a TPU / CB / Cu composite conductive fiber spin is the same as the preparation steps of Example 1, except that the CB-35% conductive fiber spinning solution in step S1 is replaced with a CB-20% conductive fiber spinning solution to obtain the TPU / CB / Cu composite conductive fiber.

[0070] Example 9

[0071] The preparation of a TPU / CB / Cu composite conductive fiber spin is the same as the preparation steps of Example 1, except that the CB-35% conductive fiber spinning solution in step S1 is replaced with a CB-10% conductive fiber spinning solution to obtain the TPU / CB / Cu composite conductive fiber.

[0072] Example 10

[0073] The preparation of a TPU / CB / Cu composite conductive fiber spin is the same as the preparation steps of Example 1, except that the CB-35% conductive fiber spinning solution in step S1 is replaced with a CB-5% conductive fiber spinning solution to obtain the TPU / CB / Cu composite conductive fiber.

[0074] Example 11

[0075] The preparation of a TPU / CB / Cu composite conductive fiber spin is the same as the preparation steps of Example 1, except that the CB-35% conductive fiber spinning solution in step S1 is replaced with a CB-40% conductive fiber spinning solution to obtain the TPU / CB / Cu composite conductive fiber. After testing, the breaking strength of the TPU / CB / Cu composite conductive fiber prepared in Example 11 is 4.9 MPa, the elongation at break is 70.3%, and the conductivity is 142.3 S / m. The mechanical properties of the TPU / CB / Cu composite conductive fiber prepared in Example 11 are slightly decreased compared with those prepared in Example 1. Therefore, in Examples 1-6 of the present invention, the CB-35% conductive fiber spinning solution is selected as the base to prepare the TPU / CB / Cu composite conductive fiber spinning solution.

[0076] Observation Figure 1It can be obtained from a in [reference] that the viscosity of the TPU / CB conductive fiber spinning solution increases rapidly with the increase of the carbon black content. For the PU15% without carbon black addition, the shear viscosity at 1 rad / s is 2.2 Pa·s respectively. When the carbon black addition amount reaches 40%, that is, CB-40%, the viscosity of the TPU / CB conductive fiber spinning solution rises sharply, reaching 1640 Pa·s. Observation Figure 1 It can be obtained from b in [reference] that the CB-40% conductive fiber spinning solution hardly has fluidity. At the same time, combining Figure 1 It can be obtained from a and b in [reference] that the viscosity of the TPU / CB conductive fiber spinning solution decreases with the increase of the shear rate, showing obvious shear thinning characteristics.

[0077] Observation Figure 2 It can be obtained from a in [reference] that the shear viscosity of the TPU / CB / Cu composite conductive fiber spinning solution gradually decreases with the increase of the shear rate, showing obvious shear thinning phenomenon; Observation Figure 2 It can be obtained from b in [reference] that at the shear rate of 0.1 rad / s, the addition of flake copper powder significantly decreases the viscosity of the TPU / CB / Cu composite conductive fiber spinning solution. Compared with the TPU / CB conductive fiber spinning solution without flake copper powder addition, that is, 35% CB, the initial viscosity of the TPU / CB / Cu composite conductive fiber spinning solution with flake copper powder addition decreases from 1800 Pa·s to about 1200 Pa·s, a decrease of 33.33%. This is because the addition of flake copper powder destroys the hard friction between carbon blacks, converts the sliding friction between carbon black and flake copper powder into rolling friction, and reduces the viscous resistance of the TPU / CB / Cu composite conductive fiber spinning solution under shear conditions.

[0078] Observation Figure 4 It can be obtained from a and b in [reference] that the carbon black has high uniformity, the size of the flake copper powder is between 4 μm and 46 μm, and the thickness size is between 0.22 μm and 2.27 μm; Observation Figure 4 It can be obtained from d and e in [reference] that the carbon black is evenly distributed inside the TPU / CB / Cu composite conductive fiber, and the distribution of Cu element is also relatively uniform.

[0079] Observation Figure 5 It can be obtained from a, b, c, d, e, f, g, h, i, j, k and l in [reference] that as the carbon black CB content in the TPU / CB / Cu composite conductive fiber gradually increases, the internal structure of the TPU / CB / Cu composite conductive fiber becomes more compact, and the cross-section of the TPU / CB / Cu composite conductive fiber changes from having obvious pores and cavities to a dense solid structure.

[0080] Observation Figure 6From a and b, it can be seen that the surface of the TPU / CB / Cu composite conductive fiber is smooth, flat, uniform in thickness and soft. The wound roll of the TPU / CB / Cu composite conductive fiber produced in large quantities is shown as Figure 6 in c. At present, the production rate in the laboratory can reach 10.613 m / min. Observation Figure 6 from d shows that using the TPU / CB / Cu composite conductive fiber as the weft yarn and the commercially available polyester yarn as the warp yarn, a flat conductive plain fabric is woven by a loom, and the fabric has good electrical conductivity.

[0081] Observation Figure 7 from a shows that as the carbon black content increases, the breaking strength of the TPU / CB conductive fiber first decreases from 36.7 MPa to 4.9 MPa, then increases to 15.9 MPa, and then decreases to 10.5 MPa. The elongation at break gradually decreases from 377.1% to 70.3% as the carbon black content increases. In order to enable the TPU / CB / Cu composite conductive fiber to reach the maximum elongation of 100% of the human joint while obtaining a highly conductive fiber, it is further determined that the carbon black content of the TPU / CB conductive fiber spinning solution is 35%. Generally, the breaking strength of the TPU / CB conductive fiber decreases with the increase of carbon black. This is because the addition of carbon black destroys the hydrogen bonds formed between the polyurethane segments, weakening the intermolecular force between the segments, thus causing a significant decrease in the breaking strength of the TPU / CB conductive fiber. As the carbon black content increases, the breaking strength of the TPU / CB conductive fiber gradually increases. This is because carbon black plays a role in physical cross-linking in the TPU / CB conductive fiber network. The increase in the addition of carbon black makes the physical entanglement points gradually increase, significantly improving the tensile ability of the TPU / CB conductive fiber.

[0082] Figure 7 In b, the resistance change rate-time images of 5%, 10%, and 20% do not appear because the addition amount is too small. After the wet drawing step in the spinning process, the distance between carbon blacks is enlarged, so that under the combined action of the electric field and thermal vibration, electrons cannot pass through the polyurethane interface to form a conductive path, resulting in the resistance exceeding the range and unable to measure the resistance change.

[0083] Observation Figure 7 from c shows that the conductivity of the TPU / CB conductive fiber shows an exponential growth as the carbon black content continuously increases. Observation Figure 7It can be obtained from f in [reference] that the conductivity of the TPU / CB / Cu composite conductive fiber increases with the increase in the addition amount of flaky copper powder. Compared with the conductivity of 29.3 S / m of the TPU / CB conductive fiber, the conductivity of Cu10% is 56.4 S / m, and its conductivity has nearly doubled, indicating that the addition of a small amount of flaky copper powder is beneficial to the significant increase in the conductivity of the TPU / CB / Cu composite conductive fiber. This is because the addition of flaky copper powder increases the conductive paths inside the TPU / CB / Cu composite conductive fiber, establishing connections between the carbon blacks that were originally independently distributed in the matrix of the TPU / CB / Cu composite conductive fiber, enabling electrons to achieve long-range transport and enhancing the conductivity. The conductivity of the obtained TPU / CB / Cu composite conductive fiber cannot reach as high as that of metal fibers. This is because there are a large number of conductive interfaces between carbon black and polyurethane, and electrons need to overcome the obstacles at this interface to achieve transmission, resulting in the fact that the obtained TPU / CB / Cu composite conductive fiber does not achieve a conductivity comparable to that of metal fibers. Considering the conductivity and mechanical properties of the TPU / CB / Cu composite conductive fiber, as well as the rheological properties of the spinning solution of the TPU / CB / Cu composite conductive fiber, it is found that Cu10% has the best comprehensive performance. It can not only have a high conductivity, but also the flaky copper powder has an obvious viscosity-reducing effect on the spinning solution of the TPU / CB / Cu composite conductive fiber. The spinning of the TPU / CB / Cu composite conductive fiber spinning solution is less difficult, with low energy consumption, and the obtained Cu10% has relatively good tensile fracture properties, which can meet the usage requirements of smart wearable devices.

[0084] Observation Figure 7 It can be obtained from d in [reference] that as the content of flaky copper powder increases, the fracture strength of the TPU / CB / Cu composite conductive fiber slightly decreases from 15.87 MPa to 12.3 MPa but there is no obvious change, while the fracture elongation rate of the TPU / CB / Cu composite conductive fiber gradually decreases from 121.86% to 74.6%. Here, the reason why the fracture strength of the TPU / CB / Cu composite conductive fiber does not show an obvious decrease is that the size of the added flaky copper powder is significantly larger than the size of the polyurethane molecular chain, and the content of flaky copper powder is low, resulting in a weak influence on the intermolecular interaction. The fracture elongation rate of the TPU / CB / Cu composite conductive fiber depends on the ability of the internal chain entanglement orientation of the TPU / CB / Cu composite conductive fiber. Due to the addition of flaky copper powder, it plays an anchoring role inside the TPU / CB / Cu composite conductive fiber, making it difficult for the stretched and oriented polyurethane molecules to return to the previous coiled and entangled state during spinning, resulting in a decrease in the fracture elongation rate of the TPU / CB / Cu composite conductive fiber. Therefore, when the addition amount of flaky copper powder decreases, the mechanical properties of the TPU / CB / Cu composite conductive fiber will decrease.

[0085] Compared with Figure 7 the TPU / CB / Cu composite conductive fiber in e of [reference],Figure 7 The resistance change rate of the TPU / CB conductive fiber of b in Figure 7 is only half of that of the e in Figure 7 and the TPU / CB / Cu composite conductive fiber of f in

[0086] Observe Figure 8 a in Figure 7 and b in Figure 7 Combined with b in Figure 7 and e in

[0087] Analysis shows that the resistance of the TPU / CB conductive fiber changes significantly with the increase of tensile strain. This change spans an order of magnitude, indicating that after the TPU / CB conductive fiber is stretched, the distance between the internal conductive particles increases significantly, resulting in a sharp increase in resistance. In contrast, although the resistance of the TPU / CB / Cu composite conductive fiber also changes with the increase of tensile strain, this change is relatively small, and the resistance value always remains within the same order of magnitude. This is mainly because the addition of flaky copper powder establishes connections in the matrix of the TPU / CB / Cu composite conductive fiber, connecting the originally independently distributed carbon blacks in series. Due to the relatively large size of the flaky copper powder, even after being stretched, it can still maintain the conductive path, thus slowing down the trend of the resistance increasing sharply with the increase of tensile strain. Figure 9 Observing a, b, c, d, e, f, g, h, and i in

[0088] it can be obtained that under the same stretching rate of fixed deformation, the resistance change law of the TPU / CB / Cu composite conductive fiber is consistent, and the TPU / CB / Cu composite conductive fiber exhibits stable performance. Figure 10 Observing a in

[0089] it can be obtained that with the increase of the stretching rate, the resistance change rate is relatively stable and the graph hardly changes. Thus, it can be concluded that the TPU / CB / Cu composite conductive fiber of the present invention has relatively stable performance, and its resistance change is not affected by the stretching rate, which is helpful for later applications in motion detection and electroheating. Figure 10 Observing b in Figure 10 it can be obtained that as the tensile deformation ranges from 1% to 40%, the resistance change rate ranges from 2.8% to 70.5%, and the resistance change rates in five cycles for each deformation are consistent, further indicating the stability of the TPU / CB / Cu composite conductive fiber. Observing c in Figure 10For d in [the above], the resistance hardly changed after more than ten cycles of washing and drying, indicating that the plain woven fabric prepared from the TPU / CB / Cu composite conductive fiber of Example 4 has excellent wash resistance. From Figure 10 As can be seen from e in [the above], 10% Cu showed high stability after 10,000 cycles, indicating that 10% Cu in Example 4 has excellent durability and reliability. Note that there is a small peak during each stretching reciprocation, which is caused by the rebound hysteresis of the TPU / CB / Cu composite conductive fiber with a high copper powder addition during the stretching process. This phenomenon is due to the pinning effect of the nanocarbon material restricting the movement recovery of the TPU segments.

[0090] Considering the mechanical tensile properties and electrical sensitivity of Cu10%, the plain woven fabric prepared from the TPU / CB / Cu composite conductive fiber of Example 4 can be applied to motion monitoring in the field of wearable electronics.

[0091] To monitor the motion monitoring performance of the TPU / CB / Cu composite conductive fiber, 10% Cu was fixed at four joint positions of laboratory volunteers and connected to a digital bridge. During the movement of the volunteers, the change in resistance was used to monitor the movement changes of human joints.

[0092] Observe Figure 11 It can be concluded that 10% Cu can be used as a resistance sensor to detect human motion behaviors, including the movement and bending of fingers, wrists, elbows, and knees. The movements of these parts can be easily detected by the TPU / CB / Cu composite conductive fiber, and the data values in multiple repeated motion detections are unified and stable, indicating that the TPU / CB / Cu composite conductive fiber has high accuracy and stability.

[0093] Air permeability reflects the ability of a fabric to exchange air with the surrounding atmospheric environment and plays an important role in maintaining and managing the thermal and moisture balance of the human body surface microenvironment. Fabrics with poor air permeability are prone to generating heat on the contact surface, making the wearer feel stuffy and leading to a decrease in human comfort. Observe Figure 12 As can be seen from a in [the above], the air permeability of the plain woven fabric prepared from the TPU / CB / Cu composite conductive fiber of Example 4 is 299.42 mm / s. Compared with spandex fabric (865.94 mm / s), polyester fabric (269.67 mm / s), denim fabric (114.58 mm / s), and cotton fabric (82.707 mm / s), the value is between them and is better than ordinary polyester, denim, and cotton fabrics, indicating that the plain woven fabric prepared from the TPU / CB / Cu composite conductive fiber of Example 4 has good air permeability.

[0094] Observe Figure 12The moisture permeability of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 was 2624.96 g / m 2 ·24 h, between that of spandex fabric (2706.15 g / m 2 ·24 h), polyester fabric (2875.86 g / m 2 ·24 h), denim fabric (2425.27 g / m 2 ·24 h), and cotton fabric (2406.83 g / m 2 ·24 h). This indicates that the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber has good moisture permeability. In addition, since both the TPU / CB / Cu composite conductive fiber and polyester are hydrophobic materials, the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 has hydrophobicity.

[0095] Observation Figure 12 in c shows that the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 is hydrophobic within 60 s, but due to the interwoven polyester sewing thread, water droplets can penetrate into the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 within 90 s.

[0096] To test the heating performance of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber, in the present invention, conductive copper sheets were pasted at both ends of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber to connect to a DC voltage source, and an infrared thermal imaging camera was used to monitor the temperature change of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in real time.

[0097] Through the electroheating test by applying different DC voltages (10 - 30 V), combined with Figure 13 and Figure 14It is concluded that under a DC voltage of 10V to 30V, the maximum temperature of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber gradually increases from 23°C (10V) to 38°C (30V). Its temperature increases with the increase of the applied DC voltage, and the processes of temperature rise and fall are both slow incremental and decremental processes. Therefore, during the use of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 for electric heating, it will not cause scalding due to a sudden rise in temperature, and has the characteristics of gentle heating and slow cooling. Experimental studies have shown that when the heating temperature of the electric heating element is higher than 60°C, it will cause the human body to feel stinging pain and even scald the skin in a very short time. If its heating temperature is only in the medium temperature range of 44°C to 60°C, the human skin will not have a relatively obvious perception in a short time, but after continuous contact with the heat source for a long time, it will cause progressive damage to the superficial dermis to the deep dermis and various tissue layers of the human skin. This kind of low-temperature scalding of the skin is irreversible. Therefore, scholars researching the heating temperature of electric heating components should pay more attention.

[0098] Figure 15 It is an infrared thermal imaging diagram of the surface temperature change of the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 under different voltages. It can be seen from the figure that as the heating voltage gradually increases, the stable maximum temperature that the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 for electric heating can reach gradually increases, and reaches 38°C at 30V.

[0099] For the interwoven plain fabric prepared from the TPU / CB / Cu composite conductive fiber in Example 4 of the present invention, the maximum temperature during electric heating within the safe voltage range of the human body is 38°C, which can achieve the function of an electric heating health care fabric on the premise of ensuring the safety of the human body voltage, and at the same time ensure that no scalding or low-temperature scalding of the human body occurs.

[0100] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and its equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A preparation method of a polyurethane / carbon black / Cu composite conductive fiber, characterized in that, It includes the following steps: Mix the flaky copper powder with the conductive fiber spinning solution of polyurethane and carbon black to obtain a polyurethane / carbon black / Cu composite conductive fiber spinning solution; wherein, the flaky copper powder accounts for 2.5% - 20% of the mass of the polyurethane / carbon black / Cu composite conductive fiber spinning solution; Use wet spinning for the polyurethane / carbon black / Cu composite conductive fiber spinning solution to obtain polyurethane / carbon black / Cu composite conductive fibers; Among them, the addition of flaky copper powder changes the sliding friction between particles in the conductive fiber spinning solution of polyurethane and carbon black into rolling friction, reduces the viscosity of the conductive fiber spinning solution of polyurethane and carbon black, and at the same time connects the independently distributed carbon black in the conductive fiber spinning solution of polyurethane and carbon black; The polyurethane / carbon black conductive fiber spinning solution is prepared according to the following method: Dissolve polyurethane in a solvent to prepare a polyurethane spinning solution with a mass fraction of 15%; Mix the 15% polyurethane spinning solution with carbon black to obtain a polyurethane / carbon black conductive fiber spinning solution; In the polyurethane / carbon black conductive fiber spinning solution, the mass of the carbon black accounts for 5% - 40% of the mass of the polyurethane in the 15% polyurethane spinning solution.

2. The preparation method of a polyurethane / carbon black / Cu composite conductive fiber according to claim 1, wherein The way of the mixing treatment is ultrasonic; and the conditions of the mixing treatment are: ultrasonic for 8h - 20h at 40°C - 60°C.

3. The preparation method of a polyurethane / carbon black / Cu composite conductive fiber according to claim 1, characterized in that, The operation of the wet spinning is: perform wet drawing treatment on the polyurethane / carbon black / Cu composite conductive fiber spinning solution to obtain polyurethane / carbon black / Cu composite conductive fibers; the conditions of the wet drawing treatment are: perform drawing under the condition that the extrusion rate is 40 mL / min - 120 mL / min, and the draw ratio is 1.2 - 2.

0.

4. The preparation method of a polyurethane / carbon black / Cu composite conductive fiber according to claim 1, characterized in that, The conditions of the mixing treatment are: stir for 10h - 36h at 40°C - 60°C.

5. The preparation method of a polyurethane / carbon black / Cu composite conductive fiber according to claim 1, characterized in that, The solvent is selected from one or two of N,N-dimethylformamide and dimethyl sulfoxide.

6. A polyurethane / carbon black / Cu composite conductive fiber obtained by the preparation method of the polyurethane / carbon black / Cu composite conductive fiber according to any one of claims 1 - 5.

7. An application of the polyurethane / carbon black / Cu composite conductive fiber according to claim 6 in the preparation of fabrics.

8. Use of the polyurethane / carbon black / Cu composite conductive fiber according to claim 6 in the preparation of a fabric, characterized in that, The application method is: Combine two polyurethane / carbon black / Cu composite conductive fibers into one weft yarn, and use 20 / 2 polyester sewing thread as the warp yarn, and interweave them to form a plain fabric.

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