Preparation method and application of conductive fiber material with negative tensile resistance response

Abstract

The present invention discloses a method for preparing a conductive fiber material with a negative tensile resistance response and its application. The preparation method comprises the following steps: S1: melt-spinning polyester to obtain polyester filaments; S2: drawing, false-twisting, and heat-setting the polyester filaments to form a polyester tensile-deformed mesh yarn; S3: immersing the polyester tensile-deformed mesh yarn in a Tris buffer solution, adding dopamine to polymerize it to form a polydopamine layer; S4: immersing the polyester mesh yarn with the polydopamine layer in a solution containing silver ions, so that the silver ions chelate with the amino and phenolic hydroxyl groups in the polydopamine; S5: reducing the silver ions on the fiber surface to silver nanoparticles through an in-situ reduction reaction, and utilizing the adsorption effect of polydopamine to uniformly load the silver nanoparticles on the surface of the polyester mesh yarn. The conductive fiber produced by the method of the present invention has a negative tensile resistance response and is suitable for use in smart wearable textile devices, medical monitoring equipment, and textile materials requiring both conductive and antibacterial properties.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive fibers, in particular to a method for preparing a conductive fiber material with a negative resistance response when stretched. Background Art

[0002] Wearable devices, due to their lightweight, flexible, and comfortable features, have shown great potential in a variety of fields, including healthcare sensors, soft robotics, and smart clothing. The rapid development of wearable devices in recent years has significantly boosted research into functional fiber materials. Conductive fibers, a key material for wearable devices, have garnered widespread attention due to their ability to sense and respond to external stimuli, such as stretch, pressure, and temperature.

[0003] Existing conductive fibers face many challenges in their application, especially the problem of increased resistance and bacterial growth during the stretching process. The increase in resistance directly leads to a decrease in conductivity, which affects the real-time data transmission and function execution of wearable devices, causing signal instability and increased energy consumption, and shortening battery life. In addition, over time, fluctuations in resistance may cause material fatigue and reduce the durability of the device. At the same time, conductive fibers are prone to breeding bacteria due to their close contact with the skin, which may cause health risks such as skin infections and allergic reactions. In addition, bacterial metabolites will form a dirt layer on the surface of the fiber, further affecting the conductivity and mechanical properties, and reducing the service life. Over a long period of time, bacterial growth may also cause odor and irritation, affecting the user experience. Therefore, the development of a conductive fiber that can maintain low resistance and has antibacterial properties during the stretching process is crucial to improving the overall performance, safety and user experience of wearable devices. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a conductive fiber material with a negative resistance response upon stretching and its application, so as to solve the problems in the prior art.

[0005] In a first aspect, the present invention provides a method for preparing a conductive fiber material having a negative resistance response upon stretching, comprising the following steps:

[0006] S1: melt spinning polyester to obtain polyester filaments;

[0007] S2: The polyester filaments are drawn, false-twisted and heat-set to form polyester stretched and deformed mesh yarns;

[0008] S3: The polyester stretched mesh is immersed in a Tris buffer solution, and dopamine is added to polymerize it to form a polydopamine layer;

[0009] S4: The polyester mesh with the polydopamine layer is immersed in a silver nitrate solution, and the silver ions chelate with the amino and phenolic hydroxyl groups in the polydopamine;

[0010] S5: The silver ions on the fiber surface are reduced to silver nanoparticles through an in situ reduction reaction, and the silver nanoparticles are evenly loaded on the surface of the polyester mesh yarn by the adsorption effect of polydopamine.

[0011] The method for preparing a conductive fiber material with a negative resistance response when stretched as described above, wherein, preferably, in step S2, the polyester filament drawing speed is 300-500 m / min, the drawing ratio is 1.5-2.5 times, the false twist speed is 800-1200 rpm, the twist range is 50-70 twists / m, the heat setting temperature is 160-180°C, and the setting time is 30-60 seconds.

[0012] In the method for preparing a conductive fiber material with a negative resistance response to stretching as described above, preferably, the pH value of the tris buffer in step S3 is 8.5-9.0, the reaction temperature of immersing the polyester stretched deformed mesh yarn in the tris buffer solution is 30-45°C, and the reaction time is 6-12 hours.

[0013] In the above-mentioned method for preparing a conductive fiber material with a negative resistance response when stretched, preferably, the concentration of the silver nitrate in step S4 is 0.05-0.10 mol / L.

[0014] As described above, a method for preparing a conductive fiber material with a negative resistance response under stretching, wherein preferably, the reducing agent of the in-situ reduction reaction is a glucose solution, the concentration of the glucose solution is 0.2-0.4 mol / L, the reaction temperature of the in-situ reduction reaction is 30-40°C, and the reaction time is 20-40 minutes.

[0015] In a second aspect, the present invention provides an application of a conductive fiber material with a negative resistance response to stretching, and the conductive fiber material with a negative resistance response to stretching prepared by the aforementioned method for preparing the conductive fiber material with a negative resistance response to stretching is used in strain sensing and antibacterial textiles.

[0016] Compared to the prior art, the conductive fiber prepared by the method of the present invention is based on stretched polyester mesh yarn. Polydopamine is grown on the polyester mesh yarn through a tris solution, and its excellent adhesion is utilized to form a uniform coating on the fiber surface. Silver nanoparticles are then plated on the fiber surface through a reduction reaction-adsorption synergistic effect, imparting excellent conductivity and antibacterial properties to the fiber. The conductive fiber of the present invention exhibits a negative resistance response when stretched, meaning that when the fiber is stretched, its resistance decreases with increasing stretching. This phenomenon is due to the unique structure of the polyester mesh yarn. During stretching, the fluffy structure shrinks, increasing the contact area between fibers and strengthening the connectivity of the conductive network, thereby reducing overall resistance. Furthermore, the silver particles plated on the fiber surface impart antibacterial properties to the fiber, effectively inhibiting bacterial growth and ensuring that the conductive fiber maintains good performance and safety over long-term use.

[0017] The preparation method of the present invention is simple and the process flow is easy to industrialize. The conductive fiber produced not only has a negative resistance response but also has antibacterial properties. It is suitable for smart wearable textile devices, medical monitoring equipment, and textile materials that require both conductive and antibacterial properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a physical picture of a conductive fiber material with a negative resistance response when stretched, produced by the present invention;

[0019] Figure 2 This is a scanning electron microscope image of a conductive fiber material with a negative resistance response when stretched, obtained by the present invention;

[0020] Figure 3 This is a resistance effect diagram of a conductive fiber material with a negative resistance response when stretched, prepared by the present invention;

[0021] Figure 4 This is a diagram showing the antibacterial effect of a conductive fiber material with a negative resistance response when stretched, prepared by the present invention;

[0022] Figure 5 This is a diagram showing the resistance change of a conductive fiber material with a negative tensile resistance response obtained by the present invention under stress loading and unloading conditions.

[0023] Figure 6 This is a graph showing the resistance change rate of a conductive fiber material with a negative resistance response to stretching produced by the present invention under different strain conditions;

[0024] Figure 7 This is a graph showing the resistance change rate of a conductive fiber material with a negative resistance response when stretched, obtained by the present invention, under different frequency conditions;

[0025] Figure 8This is a graph showing the resistance change rate of a conductive fiber material with a negative resistance response when stretched, produced by the present invention, on a model's arm. DETAILED DESCRIPTION

[0026] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0027] The present invention provides a method for preparing a conductive fiber material with a negative resistance response during stretching, which comprises the following steps:

[0028] S1: Preparation of polyester mesh yarn

[0029] The polyester pre-oriented yarn is prepared by melt spinning process and has high initial strength and good stretchability.

[0030] S2: The pre-oriented yarn is drawn, false-twisted, and heat-set to form a polyester stretched and deformed mesh yarn.

[0031] The draft ratio was set at 1.8x and the draft speed was 400 m / min. This draft ratio ensured that the fiber possessed appropriate tensile strength and elastic recovery. This drafting condition formed a stable, lattice-like, fluffy structure, providing the foundation for the subsequent negative tensile resistance effect.

[0032] The false twisting speed is set at 1000 rpm and the twist is 60 twists / meter. This speed and twist ensure that the fiber has moderate curl and bulk while maintaining good mechanical properties. The optimization of the false twisting process helps the conductive fiber produce a uniform stress distribution during the strain process, enabling it to stably exhibit negative resistance response characteristics.

[0033] The false-twisted fibers were heat-set at 170°C for 45 seconds. The heat-setting process eliminates residual stress within the fibers and stabilizes their curl structure.

[0034] S3: Dopamine polymerization

[0035] Dopamine was added to tris buffer and polyester mesh was soaked in the solution.

[0036] The pH value of the dopamine-tris solution is controlled at 8.5, the reaction temperature is 40°C, and the soaking time is 8 hours, so that dopamine can be evenly deposited on the surface of the mesh wire to form a stable polydopamine coating.

[0037] After the polymerization is completed, the fiber surface is washed with deionized water to remove unreacted dopamine. After washing, the fiber is dried at 50°C.

[0038] S4: Silver particle deposition process

[0039] An ammoniacal silver nitrate solution is prepared with a concentration of 0.08 mol / L. The fiber is immersed in the reaction solution, and the silver ions chelate with the amino and phenolic hydroxyl groups in the polydopamine.

[0040] S5: Silver ions on the fiber surface are reduced to silver nanoparticles through an in-situ reduction reaction. Polydopamine is then used for adsorption to uniformly load the silver nanoparticles onto the polyester mesh surface. A 0.3 mol / L glucose solution is used as the reducing agent for the in-situ reduction reaction.

[0041] The reaction temperature is 35°C and the reaction time is 30 minutes. During this process, silver ions are deposited to form silver particles under the reduction effect of glucose, and are fixed on the fiber surface through the chelation and adhesion of the polydopamine layer. Figure 1 As shown, a conductive fiber material with a negative resistance response upon stretching is obtained.

[0042] 1. Use electron microscope to detect the stretched negative resistance response conductive fiber material provided in Example 1. Figure 2 As shown in the figure, silver ions (Ag+) are in situ reduced to silver particles on the fiber surface, which are evenly distributed to form a conductive layer. This conductive layer significantly improves the conductivity of the fiber. Figure 3 As shown in the figure, by measuring the resistivity during stretching to assess its conductivity, the fiber's resistance decreases continuously during stretching. This is mainly because the polyester mesh is composed of multiple layers of interwoven curved fiber bundles. This structure provides a large amount of voids, allowing the fiber to stretch while maintaining its conductivity during stretching. This fluffy structure ensures excellent elasticity and flexibility while maintaining conductivity. As stretching progresses, the fibers gradually align themselves in an orderly manner. During this process, the contact between the conductive particles increases, forming new conductive paths.

[0043] Second, the conductive fiber material in Example 1 was subjected to antibacterial experiments. Figure 4 As shown, the prepared fiber was placed in a culture medium containing Staphylococcus aureus, and a decrease in the number of colonies was observed after 24 hours. The experimental results show that the silver particles on the fiber surface have a significant antibacterial effect and effectively inhibit the growth of bacteria.

[0044] 3. A motion monitoring test was performed on the strain sensor assembled using the stretched negative resistance responsive conductive fiber material obtained in Example 1. Figure 5The figure below shows the relative resistance change of the tensile negative resistance responsive conductive fiber material under stress loading and unloading. As the strain increases, the relative resistance change of the fiber continues to decrease. The fiber strain sensor exhibits negligible electrical hysteresis during the loading and unloading cycles. The above results confirm that the tensile negative resistance responsive conductive fiber material has good monotonicity in the relationship between relative resistance change and tensile strain in the absence of other interference factors, and has good signal accuracy and reliability. The resistance change of the fiber was tested within the strain range of 0-40%. Figure 6 As shown in the figure, as the strain increases, the resistance of the fiber gradually decreases, showing a typical strain-induced negative resistance response characteristic. This phenomenon is attributed to the change in the fiber arrangement, which leads to an increase in the number of conductive contact points and thus a decrease in resistance. Figure 7 The change curve of relative resistance under 40% strain at different frequencies (0.02Hz-0.10Hz) is shown. The results show that within this frequency range, the fiber exhibits a negative strain resistance response, which makes it have good application prospects in wearable devices. In addition, Figure 8 As shown in the figure, the sensor is attached to the surface of the arm and experiences tensile strain during bending. As can be seen from the relative resistance change curve, the sensor can quickly identify the bending posture of the index finger and convert it into a stable resistance change signal.

[0045] Therefore, a conductive fiber material with a negative resistance response under stretching has excellent sensing performance and reliable antibacterial properties as a wearable sensor, which has great prospects in the field of smart wearable textiles such as personal health monitoring.

[0046] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the scope of implementation of the present invention is not limited to what is shown in the drawings. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which do not exceed the spirit covered by the description and drawings, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a conductive fiber material with a negative tensile resistance response, characterized in that: The following steps are involved: S1: melt spinning polyester to obtain polyester filaments; S2: The polyester filaments are drawn, false-twisted and heat-set to form polyester stretched and deformed mesh yarns; S3: The polyester stretched mesh is immersed in a Tris buffer solution, and dopamine is added to polymerize it to form a polydopamine layer; S4: The polyester mesh with the polydopamine layer is immersed in a silver nitrate solution, and the silver ions chelate with the amino and phenolic hydroxyl groups in the polydopamine; S5: Silver ions on the fiber surface are reduced to silver nanoparticles through an in-situ reduction reaction. Polydopamine is then used to adsorb the silver nanoparticles, which are uniformly loaded onto the surface of the polyester mesh. The mesh is composed of multiple layers of interwoven curved fiber bundles, providing a large number of gaps. In step S2, the polyester filament drawing speed is 300-500 m / min, the drawing ratio is 1.5-2.5 times, the false twist speed is 800-1200 rpm, the twist range is 50-70 twists / m, the heat setting temperature is 160-180°C, and the setting time is 30-60 seconds.

2. The method for preparing a conductive fiber material with a negative resistance response under tension according to claim 1, wherein: The pH value of the tris buffer in step S3 is 8.5-9.0, the reaction temperature of the polyester stretched deformed mesh yarn immersed in the tris buffer solution is 30-45° C., and the reaction time is 6-12 hours.

3. The method for preparing a conductive fiber material with a negative resistance response under tension according to claim 1, wherein: The concentration of silver nitrate in step S4 is 0.05-0.10 mol / L.

4. The method for preparing a conductive fiber material with a negative resistance response under tension according to claim 1, wherein: The reducing agent of the in situ reduction reaction is a glucose solution, the concentration of the glucose solution is 0.2-0.4 mol / L, the reaction temperature of the in situ reduction reaction is 30-40°C, and the reaction time is 20-40 minutes.

5. An application of a conductive fiber material with a negative resistance response under tension, characterized in that: Application of the conductive fiber material with a negative tensile resistance response prepared by the method for preparing the conductive fiber material with a negative tensile resistance response according to any one of claims 1 to 4 in strain sensing and antibacterial textiles.

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