Shear thickening liquid packaging yarn with core-shell structure, preparation method of shear thickening liquid packaging yarn and composite fabric
By encapsulating the yarn with shear thickening liquid through a core-shell structure and combining the shear thickening liquid with polyurethane using coaxial wet spinning technology, continuous fibers are formed. This solves the problem of STF composite fabrics easily absorbing moisture in the air, achieving high performance and improved impact resistance and comfort.
Patent Information
- Application Number
- CN202510675885.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-11-21
AI Technical Summary
Existing STF composite fabrics are prone to absorbing moisture from the air during use, which leads to weight gain and a decrease in dispersed phase concentration, weakening shear thickening properties. Furthermore, long-term exposure to air can cause silica particles to precipitate, affecting performance stability and comfort, thus limiting their application in impact protection equipment.
The yarn encapsulated with shear thickening liquid using a core-shell structure is formed by using coaxial wet spinning technology to create a continuous fiber with shear thickening liquid as the core layer and polyurethane as the shell layer. This effectively isolates moisture and air, preventing the shear thickening liquid from being exposed. The preparation method involves using polyethylene glycol and silica-based STF as the core layer fluid and polyurethane solution as the shell layer fluid, which are simultaneously extruded through a coaxial needle and cured in a coagulation bath.
It achieves continuous and stable encapsulation of shear thickening fluid, improves the impact resistance and comfort of composite fabrics, enhances protective performance, avoids performance degradation, and improves the durability and service life of fabrics.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of impact protection materials technology, and in particular to a shear thickening liquid encapsulated yarn with a core-shell structure, its preparation method, and composite fabric. Background Technology
[0002] Shear thickening fluid (STF) is a typical non-Newtonian fluid. Due to its ability to rapidly increase viscosity under specific shear forces, it has the potential to be used in the manufacture of impact protection equipment such as liquid body armor and sports protective gear.
[0003] There are two methods for producing STF composite fabrics: impregnation and filling. Both methods directly coat the fabric surface with STF. In practical use, the STF dispersion system easily absorbs moisture from the air, leading to weight gain and a decrease in dispersed phase concentration, thus significantly affecting shear thickening performance. Furthermore, because STF is a high-viscosity, highly hygroscopic liquid, and the fabric surface is sticky, long-term exposure to air causes silica particles to precipitate, weakening the shear thickening effect. Existing fabrics still suffer from instability, poor comfort, and difficulty in storage. The encapsulation and rational utilization of STF remain challenges limiting the application of STF composite materials. Therefore, finding a more effective method for combining STF with fabrics is key to the industrial application of STF.
[0004] Current research attempts to address these issues. One approach involves encapsulating and sealing the entire fabric within a polyethylene film, while another focuses on encapsulating the STF liquid using various methods. For instance, Chinese patent application CN2024108217617 discloses installing a shear-thickening fluid within a cushioning bag to enhance protective performance; Chinese patent application CN2024101192017 discloses encapsulating the shear-thickening fluid as a hydrogel. Although these methods minimize the negative impacts of the external environment, the resulting composite fabrics still suffer from instability, poor comfort, and difficulty in preservation. The encapsulation and rational utilization of STF remain key challenges limiting the application of STF composite materials. Summary of the Invention
[0005] To address the aforementioned problems, the inventors propose a shear thickening liquid encapsulated yarn with a core-shell structure. The yarn uses shear thickening liquid as the core layer and polyurethane as the shell layer, and is manufactured via coaxial wet spinning. The shell layer effectively isolates moisture and air, preventing the shear thickening liquid from absorbing moisture and shedding, thus preventing performance degradation. This results in a continuously stable moisture-proof yarn. Embedding this yarn within a three-dimensional fabric structure endows the resulting composite fabric with excellent impact resistance and comfort, thereby completing this invention.
[0006] On one hand, the purpose of this invention is to provide a shear thickening liquid encapsulated yarn with a core-shell structure, using shear thickening liquid as the core layer and polyurethane as the shell layer, with the core layer sealed through the shell layer.
[0007] In this invention, there are no particular limitations on the shear thickening fluid used to form the core layer. Commonly used shear thickening fluids in the art can be used, such as silica (SiO2) STF, nanocomposite material-based STF (e.g., carbon nanotube-doped silica STF, aramid nanofiber-doped silica STF), and polymer microsphere-based STF based on the type of dispersed phase; polyethylene glycol (PEG)-based STF, ionic liquid-based STF, and oil-based STF based on the type of dispersion medium; and temperature-sensitive STF, magnetically responsive STF, and bio-based STF based on functional improvements, etc., which will not be elaborated here.
[0008] In a preferred embodiment of the present invention, as a shear thickening fluid for forming the core layer, a silica (SiO2) STF or a nanocomposite material-based STF (including carbon nanotube MWCNT-doped silica STF and aramid nanofiber ANF-doped silica STF) based on polyethylene glycol (PEG) as the dispersion medium is preferably used.
[0009] In a preferred embodiment of the invention, the material used to form the shell layer is preferably a solution system obtained by dissolving polyurethane (TPU) in a solvent that is soluble in polyurethane and miscible with water. The solvent is preferably selected from at least one of amides, furans, esters, alcohols, aldehydes, ethers, or ketones, more preferably from at least one of N,N-dimethylformamide (DMF), tetrahydrofuran (THF), and acetone, and most preferably N,N-dimethylformamide (DMF).
[0010] In a preferred embodiment of the present invention, the shear-thickening liquid-encapsulated yarn with a core-shell structure is prepared by coaxial wet spinning, using shear-thickening liquid as the core fluid and polyurethane solution as the shell fluid.
[0011] On the other hand, the purpose of this invention is to provide a method for preparing a shear-thickening liquid-encapsulated yarn with a core-shell structure, using a shear-thickening liquid as the core fluid and a polyurethane solution as the shell fluid, and obtaining it by coaxial wet spinning.
[0012] Coaxial wet spinning is a spinning process that involves simultaneously extruding two different fluids (core and shell materials) through a coaxial needle and solidifying them into fibers in a coagulation bath.
[0013] In this invention, coaxial wet spinning refers to a continuous spinning process in which the core and shell fluids are extruded simultaneously through a coaxial needle.
[0014] In a preferred embodiment of the present invention, such as Figure 1 As shown, the coaxial needle consists of two channels, an inner and an outer layer. The inner channel is for the core material fluid, and the outer channel is for the shell material fluid. As an injection system, it uses dual injection pumps to independently control the flow rates of the core and shell layers.
[0015] As the coagulation bath medium, water is preferred; it is miscible with the shell solvent and can induce the solidification of the shell polymer.
[0016] In a preferred embodiment of the present invention, after the shell solution (such as TPU / DMF) is extruded, the DMF solvent rapidly diffuses into the coagulation bath, causing the TPU to precipitate and solidify to form an elastic shell. The core fluid (such as STF) is encapsulated by the shell, avoiding direct contact with the coagulation bath, thus achieving continuous encapsulation of the liquid core and preventing the core shear thickener from absorbing moisture and deteriorating due to exposure. Moreover, the interfacial chemical bonding between the TPU shell and the STF core differs from simple physical encapsulation, effectively promoting sealing stability and helping to improve the impact resistance of the composite fabric.
[0017] Continuous fibers with a core-shell structure are formed by coaxial wet spinning. The polyurethane shell completely encapsulates the shear thickening fluid of the core layer, thereby preventing the shear thickening fluid of the core layer from being exposed to air.
[0018] In a further preferred embodiment, a dynamic sealing method is adopted, that is, the injection is started and stopped in stages to avoid leakage at the fiber ends, and the polyurethane shell layer achieves good sealing of the fiber ends of the core layer shear thickening liquid.
[0019] Specifically, the shell fluid is injected first, followed by the core fluid to seal the starting end of the fiber. Once the fiber has been produced to the required length, the injection of the core fluid is stopped first, followed by the injection of the shell fluid to seal the other end of the fiber.
[0020] In a preferred embodiment of the method for preparing shear thickening fluid-encapsulated yarn with a core-shell structure according to the present invention, as the core fluid, STF with polyethylene glycol (PEG) as the dispersion medium and silica (SiO2) as the dispersed phase is used, wherein the concentration of silica is 40-80 wt%, more preferably 50%-70 wt%; or, a third phase, such as carbon nanotubes or nano-aramid fibers, may be doped into the dispersion, wherein the concentration of the doped third phase is preferably no more than 5 wt%, more preferably 0.03%-3 wt%.
[0021] In a preferred embodiment of the method for preparing shear-thickening liquid-encapsulated yarn with a core-shell structure according to the present invention, a TPU / DMF solution with a concentration of 15-50 wt%, more preferably 20%-40 wt%, is used as the shell fluid.
[0022] In a preferred embodiment of the method for preparing shear-thickening liquid-encapsulated yarn with a core-shell structure according to the present invention, the shell fluid injection rate is 160-210 μL / min, more preferably 180-200 μL / min; the core fluid injection rate is 50-150 μL / min, more preferably 60-140 μL / min; and the coagulation bath temperature does not exceed 60°C, more preferably 30°C-50°C.
[0023] In a preferred embodiment of the method for preparing shear-thickening liquid-encapsulated yarn with a core-shell structure according to the present invention, the two ends of the fiber are sealed by stepwise injection.
[0024] The resulting shear-thickened liquid-encapsulated yarn with a core-shell structure is cured and then dried. For example, it is soaked in water for 24 hours to fully cure the outer TPU layer, while reducing the time error between the earlier and later extruded fibers and their contact with water. Then it is dried in an oven at 40°C for 1 hour.
[0025] In another aspect, the present invention aims to provide a composite fabric using a shear thickening liquid encapsulating yarn with a core-shell structure, wherein the encapsulating yarn is located in the middle layer of the fabric and the outer fabric structure provides rigidity for the encapsulating yarn.
[0026] In a preferred embodiment of the present invention, a shear thickening liquid encapsulated yarn with a core-shell structure is used as a weft yarn and interwoven with high-performance fiber yarns such as para-aramid PPTA, ultra-high molecular weight polyethylene UHMWPE, or carbon fiber CF. It can be woven (warp and weft interweaving), knitted (weft knitting or warp knitting), etc., to form a composite fabric, which has excellent impact resistance, puncture resistance and comfort.
[0027] In a preferred embodiment, to protect the TPU / STF encapsulation yarn, the encapsulation yarn is wrapped inside the fabric through a fabric structure design. Specifically, this can be achieved using three-dimensional woven structures such as corner interlocking, orthogonal, or spaced weft knitting or warp knitting structures such as warp-inserted, weft-inserted, or spaced weft knitting. Figure 3 As shown. Attached Figure Description
[0028] Figure 1 A schematic diagram of a coaxial wet spinning apparatus according to a preferred embodiment of the present invention is shown;
[0029] Figure 2 This shows an STF / TPU composite yarn;
[0030] Figure 3 This illustrates a three-dimensional woven fabric structure according to a preferred embodiment of the present invention;
[0031] Figure 4 This invention illustrates a preferred embodiment of the M-STF / TPU / PPTA composite fabric laminate structure.
[0032] Figure 5 The results of the dynamic impact test in Example 1 are shown, where (a) is the time-stress curve, (b) is the displacement-force curve, and (c) is the time-energy curve.
[0033] Figure 6 The deformation of the fabric after impact is shown in Test Example 1, where (a) is an M-STF / TPU / PPTA composite and (b) is a PPTA fabric. Detailed Implementation
[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent. While various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.
[0035] Example 1: Preparation of Encapsulated Yarn
[0036] Nano-silica (SiO2) was prepared as the dispersion phase, PEG200 as the dispersion medium, and STF with a SiO2 content of 70% was added. MWCNT with a mass fraction of 0.03% was added and ultrasonically dispersed for 30 min to serve as the core layer fluid.
[0037] A TPU / DMF solution with a mass ratio of 3:7 was prepared as the shell fluid, and after degassing, it was loaded into an injection pump.
[0038] Set the shell velocity to 200 μL / min, the core velocity to 100 μL / min, and the coagulation bath temperature to 40℃, and use step-by-step injection to achieve fiber end sealing;
[0039] After soaking the fibers in deionized water for 24 hours, they are dried at 40°C to obtain continuous encapsulation yarn M-STF / TPU, such as... Figure 2 As shown.
[0040] The prepared encapsulated yarn retains ≥90% density after being washed 50 times according to the standard washing procedure.
[0041] Example 2: Preparation of Encapsulated Yarn
[0042] Nano-silica (SiO2) was prepared as the dispersion phase, PEG200 as the dispersion medium, and STF with a SiO2 content of 50% was added. MWCNT with a mass fraction of 1% was added and ultrasonically dispersed for 30 min to serve as the core layer fluid.
[0043] A TPU / DMF solution with a mass ratio of 3:7 was prepared as the shell fluid, and after degassing, it was loaded into an injection pump.
[0044] Set the shell velocity to 180 μL / min, the core velocity to 80 μL / min, and the coagulation bath temperature to 40℃, and use step-by-step injection to achieve fiber end sealing.
[0045] The fibers are soaked in deionized water for 24 hours and then dried at 40°C to obtain continuous yarn.
[0046] The prepared encapsulated yarn retains ≥90% density after being washed 50 times according to the standard washing procedure.
[0047] Example 3: Preparation of Encapsulated Yarn
[0048] A STF with 60% SiO2 content was prepared as a core fluid by ultrasonic dispersion for 30 min using nano-silica (SiO2) as the dispersion phase, PEG200 as the dispersion medium, and SiO2 content as 60%.
[0049] A TPU / DMF solution with a mass ratio of 2.5:7.5 was prepared as the shell fluid, and after degassing, it was loaded into an injection pump.
[0050] Set the shell velocity to 180 μL / min, the core velocity to 120 μL / min, and the coagulation bath temperature to 40℃, and use step-by-step injection to achieve fiber end sealing.
[0051] The fibers were soaked in deionized water for 24 hours and then dried at 40°C to obtain continuous encapsulated yarn M-STF / TPU.
[0052] The prepared encapsulated yarn retains ≥90% density after being washed 50 times according to the standard washing procedure.
[0053] Example 4: Preparation of Composite Fabrics
[0054] Weaving Figure 4 The composite fabric with the five-layer corner interlocking structure shown is replaced by the encapsulation yarn M-STF / TPU obtained in Example 1. Figure 4 The weft yarns in the middle layer of the structure are woven, while the other weft and warp yarns are made of 1000D para-aramid PPTA yarn.
[0055] Comparative Example 1
[0056] Weaving Figure 4 The composite fabric shown has a five-layer interlocking structure and is made entirely of 1000D para-aramid PPTA yarn.
[0057] Test Example 1: Dynamic Puncture and Low-Voltage Impact Test
[0058] Dynamic puncture and low-speed impact tests were conducted on the M-STF / TPU / PPTA composite fabric obtained in Example 4 and the pure PPTA fabric in Comparative Example 1 using an INSTRON 9440 drop hammer impact testing machine.
[0059] The parameters of the drop hammer impactor were set to an energy gradient of 30 J and a counterweight of 239 g (16 mm diameter) for the hemispherical punch. The drop hammer impact testing machine and tools were used to photograph and analyze the puncture edges of the laminated fabrics after dynamic puncture tests to investigate the effect of STF on the puncture resistance of aramid fibers. Differences in puncture resistance between fabrics could be assessed by comparing the degree of fiber breakage and the elongation of the fabric.
[0060] The fabric structural parameters and impact energy are shown in the table below:
[0061] sample number of floors Thickness (mm) <![CDATA[Areal density (g / m 2 )]]> Impact energy (J) M-STF / TPU / PPTA (Example 4) 5 7.78 15873 30J PPTA (Comparative Example 1) 10 7.88 14089 30J
[0062] Figure 5 The time-stress curves (a), time-energy curves (b), and displacement-force curves (c) of the M-STF / TPU / PPTA composite fabric and pure PPTA fabric samples are shown.
[0063] in, Figure 5 (a) shows that both fabrics exhibit “closed” curves, indicating that both fabrics can effectively disperse and absorb impact energy, providing protection.
[0064] Contact force and displacement response are considered important characteristics of a material's response to impact loads. The table above shows that the peak maximum force of the M-STF / TPU / PPTA composite fabric is 19.51% higher than that of the pure PPTA fabric, indicating that the shear thickening effect of M-STF in the M-STF / TPU / PPTA composite fabric plays a positive role in improving the impact resistance of the composite fabric.
[0065] from Figure 5 (b) It can be seen that the force-displacement curves of the two types are significantly different. PPTA fabric has a displacement of more than 20 mm when the force value is very low, and the slope is low, indicating that the deformation during the impact is large, the impact load is small, and the stiffness is small. It mainly dissipates energy through fabric deformation. On the other hand, the force-displacement curve of M-STF / TPU / PPTA composite fabric has a larger slope. As shown in the table above, the maximum displacement is reduced by 23.18%, showing its excellent stiffness characteristics. The high stiffness is mainly due to the high viscosity of M-STF and the TPU tube with a higher modulus than PPTA fiber, thereby enhancing the modulus of M-STF / TPU / PPTA composite fabric.
[0066] This results in a unique shear thickening effect upon impact energy activation, enabling faster energy absorption and dissipation. This indicates that, at the same impact energy, the M-STF / TPU / PPTA composite fabric exhibits superior impact resistance. Figure 5 (a) and Figure 5(c) It can be seen that the STF / TPU / PPTA composite fabric has a faster energy absorption capacity because of the presence of STF in the M-STF / TPU / PPTA composite fabric.
[0067] The dynamic impact performance results are shown in the table below:
[0068]
[0069] Figure 6 The image shows the fabric morphology after dynamic impact, from... Figure 6 It can be seen that both fabrics exhibit depressions and bulges on their front (attack side) and back (back side). When the test sphere contacts the fabric surface, the fabric surface undergoes a near-circular deformation, resulting in circular bulges. As the test displacement increases, the impact force on the fabric gradually increases, and the bulges become more pronounced. The back bulge of the M-STF / TPU / PPTA fabric (1.1cm) is smaller than that of the PPTA fabric (1.3cm), and the fabric surface deformation is also smaller, 0.8 times that of the PPTA fabric. This may be due to the increased stiffness of the M-STF / TPU / PPTA composite fabric, with the STF buffer in the middle layer absorbing more energy, thus reducing the energy absorption during fabric deformation.
[0070] The present invention has been described in detail above with reference to specific embodiments and / or exemplary examples, as well as the accompanying drawings. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
Claims
1. A shear-thickening liquid encapsulated yarn with a core-shell structure, wherein the shear-thickening liquid is used as the core layer and polyurethane is used as the shell layer, and the core layer is sealed through the shell layer.
2. The shear-thickening liquid encapsulated yarn with a core-shell structure as described in claim 1, wherein, As a shear thickening fluid (STF) for forming the core layer, an STF based on polyethylene glycol (PEG) as the dispersion medium and nano-silica (SiO2) as the dispersed phase, or an STF based on nanocomposite materials as the dispersed phase (the dispersed phase also includes carbon nanotubes (MWCNT), aramid nanofibers (ANF), etc.) is used.
3. The shear-thickening liquid encapsulating yarn with a core-shell structure as described in claim 1, wherein, As the material used to form the shell, a solution system obtained by dissolving polyurethane (TPU) in a solvent that is soluble in polyurethane and miscible with water is used, wherein the solvent is selected from at least one of amides, furans, esters, alcohols, aldehydes, ethers or ketones; the solvent is preferably at least one of N,N-dimethylformamide (DMF), tetrahydrofuran (THF), and acetone.
4. The shear-thickening liquid encapsulated yarn with a core-shell structure as described in claim 1, wherein, The shear-thickening fluid-encapsulated yarn with a core-shell structure is produced by coaxial wet spinning, using shear-thickening fluid as the core fluid and polyurethane solution as the shell fluid.
5. A method for preparing shear-thickening fluid-encapsulated yarn with a core-shell structure, wherein the shear-thickening fluid is used as the core fluid and the polyurethane solution is used as the shell fluid, and the yarn is prepared by coaxial wet spinning.
6. The preparation method according to claim 5, wherein, As a coaxial needle, it consists of two channels, an inner and an outer layer. The inner layer is connected to the core material fluid, and the outer layer is connected to the shell material fluid. As an injection system, dual injection pumps are used to independently control the flow rates of the core fluid and the shell fluid. As the coagulation bath medium, a medium that is miscible with the shell solvent and can induce the solidification of the shell polymer is used. At least one of water, ethanol, NaCl solution, and surfactant is selected, with water being preferred.
7. The preparation method according to claim 5, wherein, A dynamic sealing method is adopted, that is, the injection is started and stopped in stages to avoid leakage at the fiber ends. The polyurethane shell layer achieves a good seal at the fiber ends of the core layer shear thickening liquid.
8. The preparation method according to claim 5, wherein, As the core fluid, polyethylene glycol (PEG) is used as the dispersion medium, and the dispersed phase is silica (SiO2)-based STF, wherein the concentration of silica in the dispersed phase is 40-80 wt%, more preferably 50%-70 wt%; or, a third phase, such as carbon nanotubes or nano-aramid fibers, may be doped into the dispersion, and the concentration of the doped third phase is preferably no more than 5 wt%, more preferably 0.03%-3 wt%. As the shell fluid, a TPU / DMF solution with a concentration of 15-50 wt%, more preferably 20%-40 wt%, is used.
9. The preparation method according to claim 5, wherein, The injection rate of the shell fluid is 160-210 μL / min, more preferably 180-200 μL / min; the injection rate of the core fluid is 50-150 μL / min, more preferably 60-140 μL / min; and the coagulation bath temperature is 15℃-60℃, more preferably 30℃-50℃.
10. A composite fabric using shear thickening liquid encapsulation yarn with a core-shell structure, wherein the encapsulation yarn is located in the middle layer of the fabric, and the outer layer of fabric provides rigid support for the encapsulation yarn.