Cashmere composite yarn loaded with aerogel shell layer and preparation method of cashmere composite yarn

Abstract

The invention relates to the technical field of textile composite materials, in particular to cashmere composite yarn loaded with an aerogel shell layer and a preparation method of the cashmere composite yarn. The invention discloses cashmere composite yarn loaded with an aerogel shell layer and a preparation method of the cashmere composite yarn. The cashmere composite yarn is used for preparing aerogel-cashmere composite yarn supported by in-situ microcrystalline gelation and negative pressure microfluidic technologies. The composite yarn takes cashmere staple fiber as a matrix, after being activated by atmospheric pressure oxygen plasma, the cashmere staple fiber is put into an oligosiloxane-quaternary ammonium salt solution, gel in-situ coating is formed on the surface of the cashmere staple fiber, then the cashmere staple fiber is sent into a freezing-vacuum continuous flow control channel to be subjected to instantaneous freezing, vacuum sublimation and rewetting polycondensation, a nano aerogel shell layer is formed on the surface of the fiber, and the composite yarn is obtained. And blending with aerogel modified polyester staple fibers, twisting and shaping to obtain the cashmere composite yarn loaded with the aerogel shell layer. According to the method, the problems of weak interface bonding of aerogel and cashmere, insufficient warm-keeping gain and hard hand feeling are solved, green and efficient production is realized, and a low-input and fast-output high-added-value functional yarn upgrading path is provided for an industrial end.

Description

[0001] This invention relates to the field of textile composite materials technology, specifically to a cashmere composite yarn with an aerogel shell and its preparation method. Background Technology

[0002] Cashmere fibers are renowned for their softness and warmth, but the insulating properties of traditional cashmere products are limited by the material's inherent thermal conductivity. Aerogels, on the other hand, are porous materials with extremely high porosity and ultra-low density, with densities as low as 0.003 g / cm³. 3 With a porosity of 80% to 99% or higher, silica aerogel possesses an extremely low thermal conductivity and excellent thermal insulation properties. However, pure silica aerogel is inherently fragile, with weak internal particle connections and a tendency to generate dust. Combining aerogel materials with fibers is considered an effective way to improve their practicality. The introduction of fibers can enhance the mechanical strength and thermal insulation performance of the aerogel structure, reduce aerogel dust release, and improve the ease of material application.

[0003] In recent years, researchers have proposed the concept of aerogel fibers, which involves preparing aerogels into fibrous forms or combining them with textile fibers to combine the low thermal conductivity of aerogels with the flexibility of fibers. For example, CN120759003A discloses a method for preparing hybrid aerogel fibers, in which sodium hydroxide is added to a cellulose dispersion to adjust the pH to alkaline, viscose and silane coupling agent are added, and ultrasonic stirring is performed to obtain a mixed spinning solution; the mixed spinning solution is extruded through a wet spinning device into a coagulation bath for drawing to obtain wet fibers, which are then freeze-dried to obtain hybrid aerogel fibers; CN120738785A discloses a three-dimensional porous aerogel fiber and its preparation method and application, in which a polyurethane spinning solution is prepared using N,N-dimethylformamide as a solvent, and then the polyurethane spinning solution is wet-spun to obtain wet gel fibers, which are then immersed in an organic solvent for solvent exchange, and dried after solvent exchange to obtain aerogel fibers. However, most existing aerogel fibers suffer from weak mechanical properties and complex preparation processes. For example, pure silicate aerogel fibers are prone to breakage when stretched or bent, making them difficult to use directly as fabric fibers; at the same time, their manufacturing often relies on complex processes such as sol-gel combination supercritical drying or freeze-drying, making continuous production difficult to achieve.

[0004] In summary, how to comprehensively utilize new materials and green processes to innovate a blending process that can improve the mechanical and thermal insulation properties of yarns, enhance blending uniformity and functional expansion capabilities, and meet the requirements of continuous and clean production has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a cashmere composite yarn with an aerogel shell and its preparation method, so as to solve the technical problems in the prior art such as limited mechanical properties of aerogel fibers, poor blending uniformity, insufficient functional expansion, and low level of continuous and green manufacturing.

[0006] The specific technical solution is as follows: A cashmere composite yarn loaded with an aerogel shell and its preparation method are disclosed. The preparation method involves first activating cashmere fibers with plasma, performing sol-gel polycondensation and constructing a nano-aerogel shell in situ, then blending them with aerogel-modified polyester staple fibers in a certain proportion, and finally obtaining the cashmere composite yarn loaded with an aerogel shell through semi-worsted spinning, saturated steam twisting and heat setting.

[0007] Furthermore, the sol-gel polycondensation is carried out by immersing plasma-activated cashmere short fibers in an oligomeric siloxane-quaternary ammonium salt pregel solution, stirring at a uniform speed and heating to complete the sol-gel polycondensation.

[0008] Furthermore, the in-situ construction of the nano-aerogel shell involves immediately freezing cashmere fibers to form a microcrystalline-gel framework after sol-gel polycondensation, followed by vacuum sublimation, and finally rehydration polycondensation to obtain the nano-aerogel shell.

[0009] Furthermore, the instantaneous freezing is the instantaneous freezing of the sol on the fiber surface to form microcrystals at a low temperature of -45°C; the vacuum sublimation is the sublimation of the solvent under reduced pressure immediately after the formation of microcrystals; and the rewetting polycondensation is the process of increasing the single yarn strength of the yarn by adding water vapor.

[0010] Furthermore, the cashmere composite yarn loaded with aerogel shell is prepared by humidifying and heating cashmere fibers with nano-aerogel shells and twisting them into yarn, causing the aerogel-modified polyester staple fibers to partially melt and form bonding nodes to weld the aerogel microsheath onto the cashmere fibers, thus completing the one-step continuous preparation of the cashmere composite yarn loaded with aerogel shell.

[0011] A cashmere composite yarn with an aerogel shell and its preparation method include the following steps: S1: Select clean cashmere short fibers and wash them with oil. Prepare an oligomeric siloxane-quaternary ammonium salt pregel solution. Tetraethoxysilane and methyltriethoxysilane are partially hydrolyzed in hydrochloric acid for 30 minutes to generate a transparent sol containing siloxane oligomers. Then, (3-trimethoxysilylpropyl)dimethyloctadecylammonium chloride is added to adjust the pH to 7.5, resulting in a uniform, low-viscosity pregel solution. The cashmere fiber surface is activated using an atmospheric pressure oxygen plasma surface treatment machine. The active oxygen particles instantly etch and oxidize the cashmere surface, generating -OH and -COOH anchor points. The fiber is then immediately immersed in the pregel sol for impregnation.

[0012] S2: The impregnated cashmere fibers, along with the pre-gel solution, are transferred into a temperature-controlled water bath reactor. The mixture is stirred at low speed at 25°C for 10 minutes to allow the sol to spread evenly on the fiber surface. Then, the temperature is increased to 50°C at 1°C / minute and held for 30 minutes to promote further condensation of the oligomers and form a flexible SiO2 gel layer containing quaternary ammonium groups, thus completing the in-situ sol-gel coating. The fibers are then removed and placed in a hot air circulating oven for pre-drying at 80°C for 5 minutes, followed by curing at 120°C for 10 minutes to obtain cashmere short fibers with an antibacterial gel layer on the surface.

[0013] S3: The cashmere short fibers coated with gel obtained in S2 are evenly laid on a perforated stainless steel mesh belt and then fed into a freeze-vacuum continuous flow control channel. Instant freezing section: The temperature in the front zone of the channel is -45℃. The fibers stay for 25 seconds, and the solution in the pre-gel is rapidly frozen into ice crystals, forming a microcrystalline-gel skeleton. The fibers are then fed into the vacuum sublimation section and stay there for 6 minutes. The ice crystals sublimate directly and are captured by low-temperature cold hydrazine, with a weight loss rate of ≤5%. The fibers then enter the polycondensation-rehydration section, where 50℃ water vapor is introduced through 0.2mm micropores to obtain an aerogel shell. After exiting the channel, the fiber moisture regain is <2%, and there are no visible cracks on the shell and the cashmere surface.

[0014] S4: The aerogel shell-cashmere composite short fiber prepared in S3 is blended with aerogel-modified polyester fiber at a ratio of 3:7. The mixture is then combed into a mixed bundle of 120 fibers per bundle. The bundle is placed in the saturated steam zone of the steam-twisting integrated unit. The fiber moisture content rises rapidly to 18%, and the shell modulus decreases to avoid twisting brittleness. The fiber is then ring spun to obtain single yarns. After steam setting treatment to reduce twist shrinkage, two single yarns are taken and initially twisted in the Z direction and then re-twisted in the S direction to form a double strand, which is the final product, cashmere composite yarn loaded with aerogel shell.

[0015] Furthermore, the activation described in S1 is performed under the following conditions: oxygen flow rate of 18-22 L / min, radio frequency power of 90-110 W, and processing time of 1.5-2.5 minutes.

[0016] Furthermore, the vacuum sublimation section described in S3 has a vacuum level of 100~150 Pa.

[0017] Furthermore, the aerogel shell described in S3 has a density of 0.16~0.20 g / cm³. 3 .

[0018] Furthermore, the aerogel-modified polyester fiber described in S4 is a commercially available 1.67 dtex × 38 mm fiber with a density of 1.03 g·cm³. -3 Thermal conductivity 0.020 W·m -1 ·K -1The SiO2 aerogel content is 2.8 wt%, and it is manufactured according to the masterbatch-melt spinning route disclosed in CN103388193B.

[0019] Furthermore, the cashmere composite yarn with the aerogel shell described in S5 has a yarn thermal resistance of 0.190~0.200m. 2 ·K / W.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) In-situ growth of aerogel network significantly improves the thermal insulation performance of yarn: Aerogel forms a shell directly on the surface of cashmere fibers, and the aerogel is evenly and continuously distributed in the yarn. Each fiber carries a highly porosity aerogel layer, which significantly reduces the overall thermal conductivity of the yarn and improves its thermal insulation performance. Compared with traditional blended yarns, the yarn has a lower thermal conductivity and a longer-lasting thermal insulation effect at the same aerogel content.

[0021] (2) Strong interfacial bonding and excellent mechanical properties: The carboxyl groups introduced by plasma improve the bonding force between the aerogel and the cashmere keratin scales. The nodes formed by the melting of aerogel-modified polyester staple fibers firmly weld the aerogel shell to the fibers and bond each fiber together, forming a three-dimensional interconnected structure. As a result, the yarn strength and abrasion resistance are greatly improved, and it will not break during processing like traditional aerogel fibers. The presence of the aerogel shell actually enhances the fiber's compressive strength and resilience, and the yarn has good flexibility and elasticity.

[0022] (3) Good blending uniformity and stable yarn quality: The present invention adopts the strategy of first growing aerogel in situ and then spinning yarn. Each cashmere fiber is uniformly coated with aerogel, avoiding random aggregation of aerogel phase in the yarn. Compared with pre-made aerogel fiber blending, the aerogel content of each segment of the yarn is consistent, the product performance is uniform, and the problem of uneven blending caused by aerogel fiber breakage in traditional methods is solved.

[0023] (4) Strong functional scalability: Functional additives can be flexibly added during the pregelation solution stage of this invention, so that the final yarn can have other functions in addition to warmth. Since the aerogel network is directly loaded on the fiber surface, these functional components can be firmly embedded in the microporous structure, realizing the preparation of multifunctional integrated yarn.

[0024] (5) Continuous and green process: The entire process, including fiber surface treatment, spraying, microfluidic freeze drying, and twisting, is integrated into a continuous production line. It does not require supercritical drying with high pressure vessels or organic solvents. It mainly uses aqueous solution system and vacuum freezing technology, which has high energy efficiency and is environmentally friendly. The combination of atmospheric pressure plasma and vacuum microfluidics enables the production process to be scaled up sustainably, making it suitable for continuous industrial production. Attached Figure Description

[0025] Figure 1This is a flowchart illustrating a cashmere composite yarn with an aerogel shell and its preparation method according to the present invention.

[0026] Figure 2 This is a structural diagram of the cashmere composite yarn with an aerogel shell prepared according to the present invention.

[0027] Figure 3 This is a comparison chart of the experimental results for thermal resistance, shell density, shell retention rate, single yarn strength, and antibacterial rate in Experiment Example 1. Detailed Implementation

[0028] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0029] The technical solution designed by this invention to solve the existing problems includes the following key points: 1. Interface Coupling Mechanism Traditional physical adsorption-based composite methods generally face problems such as high interfacial energy barriers and insufficient compatibility, leading to easy desquamation and loss of the aerogel phase under repeated wet conditions. This study introduces low-temperature plasma-induced generation of surface polar groups and combines it with sol-gel in-situ polycondensation technology to construct a covalently bonded siloxane transition layer on the surface of cashmere fibers, achieving a three-step coupling of activation, anchoring, and shell formation. This technology significantly increases the chemical bond density between the aerogel phase and the keratin matrix, improving the interfacial shear strength by two orders of magnitude, laying a thermodynamically stable foundation for subsequent washability and durability.

[0030] 2. Construction of nanoporous structures Conventional hot air drying is dominated by capillary tension, leading to easy collapse of pore walls and difficulty in maintaining high porosity at the mesopore scale. This study employs a combination of instantaneous deep cryogenics and vacuum sublimation. Instantaneous deep cryogenics are completed in the freezing chamber at the front of a cryo-vacuum continuous flow control channel. -45℃ refrigerant nozzles are placed at the top of a stainless steel tunnel, with an air velocity of 3–5 m / s. Fibers are laid flat on a perforated stainless steel mesh belt, with the surface and core simultaneously reaching -45℃ to form an ice crystal skeleton <5 nm. Vacuum sublimation occurs in the middle of the same channel, with step-by-step evacuation at 100–150 Pa and a cold trap coil at -10℃, resulting in a weight loss of ≤5%. Rehydration and condensation occur at the rear of the channel, with water vapor introduced through micropores. This process utilizes the phase transition sequence from ice crystal nucleation to growth and sublimation, using solvent crystals as a removable template, successfully constructing a continuous and highly porous nanoporous network on the surface of single fibers. This effectively avoids surface tension-driven pore wall shrinkage, reducing the shell density to 0.16–0.20 g / cm³. 3 .

[0031] 3. Introduce a saturated water vapor field Aerogel shells exhibit an inherent contradiction between high porosity and low fracture toughness, and traditional ring spinning and twisting easily induces the propagation of microcracks at the shell-matrix interface. This study innovatively introduces a saturated water vapor field into the twisting region, which reduces the glass transition temperature of the shell through instantaneous plasticization, causing it to undergo viscoelastic deformation rather than brittle fracture under shear stress. Subsequently, low-temperature shaping locks the twist angle, achieving a synergistic effect of softening, twisting, and curing.

[0032] 4. Integrated antibacterial and structural design Traditional finishing antibacterial agents are prone to migration due to washing, UV exposure, and hydrolysis, posing a risk of environmental accumulation. This study introduces quaternary ammonium cations into a siloxane network via a co-precursor approach, chemically bonding them to the pore walls during sol-gel polymerization to form an integrated antibacterial-structural system. This design ensures the controlled release of antibacterial groups throughout the fiber's lifespan. After 30 washes, the inhibition rate against Staphylococcus aureus and Bacillus coli remained ≥90%, with no detectable free bactericides, achieving a transformation of antibacterial function from surface treatment to bulk integration.

[0033] Example 1 A cashmere composite yarn with an aerogel shell and its preparation method include the following steps: S1: Select 10g of clean cashmere short fibers and wash them with oil. Prepare an oligomeric siloxane-quaternary ammonium salt pregel solution. Add 7.5g of tetraethoxysilane and 2.3g of methyltriethoxysilane to 0.5mL of 0.01mol / L hydrochloric acid and partially hydrolyze for 30 minutes to generate a transparent sol containing siloxane oligomers. Then add 0.25g of (3-trimethoxysilylpropyl)dimethyloctadecylammonium chloride and adjust the pH to 7.5 to obtain 100g of a uniform, low-viscosity pregel solution. Activate the cashmere fiber surface using an atmospheric pressure oxygen plasma surface treatment machine. Discharge with pure oxygen at 20L / min and 100W radio frequency for 2 minutes at atmospheric pressure. The active oxygen particles instantly etch and oxidize the cashmere surface, generating -OH and -COOH anchor points. Immediately transfer the fiber to the pregel sol for impregnation.

[0034] S2: The impregnated cashmere fibers, along with the pre-gel solution, are transferred into a temperature-controlled water bath reactor. The mixture is stirred at low speed at 25°C for 10 minutes to allow the sol to spread evenly on the fiber surface. Then, the temperature is increased to 50°C at 1°C / minute and held for 30 minutes to promote further condensation of the oligomers and form a flexible SiO2 gel layer containing quaternary ammonium groups, thus completing the in-situ sol-gel coating. The fibers are then removed and placed in a hot air circulating oven for pre-drying at 80°C for 5 minutes, followed by curing at 120°C for 10 minutes to obtain cashmere short fibers with an antibacterial gel layer on the surface.

[0035] S3: The cashmere short fibers coated with gel obtained in S2 are evenly laid on a perforated stainless steel mesh belt and then fed into a freeze-vacuum continuous flow control channel. Instant freezing section: The temperature in the front area of ​​the channel is -45℃. The fibers stay for 25 seconds, and the solution in the pre-gel is rapidly frozen into ice crystals, forming a microcrystalline-gel skeleton. It is then sent to the vacuum sublimation section with a vacuum degree of 120Pa. It stays in the vacuum sublimation section for 6 minutes. The ice crystals sublimate directly and are captured by low-temperature cold hydrazine. The weight loss rate is ≤5%. Then it enters the condensation-rehumidification section. 50℃ water vapor is introduced through 0.2mm micropores to maintain the local relative humidity at 55%. The wall temperature is raised to 50℃ and it stays for 4 minutes to obtain an aerogel shell. After exiting the channel, the fiber moisture regain is <2%, and there are no visible cracks on the shell and the cashmere surface.

[0036] S4: Take 10g of the aerogel shell-cashmere composite short fiber prepared in S3 and blend it with 23.3g of aerogel-modified polyester fiber. The blended fiber is made into a mixed bundle of 120 fibers / strip by three-pass combing. The bundle is placed in the saturated steam zone of the steam-twisting integrated unit. The temperature is set at 80℃ and the relative humidity is 100%. The fiber moisture content rises rapidly to 18%, and the shell modulus decreases to avoid twisting brittleness. Then, ring spinning is performed to obtain single yarns. After obtaining single yarns, they are steamed and set at 90℃ and 40% relative humidity for 30 seconds to reduce twist shrinkage. Two single yarns are taken and initially twisted in the Z direction and then re-twisted in the S direction to form a double strand, which is the final product, cashmere composite yarn loaded with aerogel shell.

[0037] Example 2 The preparation method is the same as in Example 1, except that: S1: Replace 2 minutes of 20L / min pure oxygen and 100W radio frequency discharge at atmospheric pressure with 1.5 minutes of 18L / min pure oxygen and 90W radio frequency discharge at atmospheric pressure; S3: Vacuum degree of 120Pa is replaced with vacuum degree of 100Pa; S4: The saturated steam zone of the integrated steam-twisting unit, with a set temperature of 80℃, is replaced with the saturated steam zone of the integrated steam-twisting unit, with a set temperature of 78℃; the yarn setting treatment at 90℃ and 40% relative humidity for 30 seconds is replaced with the yarn setting treatment at 85℃ and 40% relative humidity for 25 seconds. All other steps are the same.

[0038] Example 3 The preparation method is the same as in Example 1, except that: S1: Replace 20L / min pure oxygen and 100W radio frequency discharge at atmospheric pressure for 2 minutes with 22L / min pure oxygen and 110W radio frequency discharge at atmospheric pressure for 2.5 minutes. S3: Vacuum degree of 120Pa is replaced with vacuum degree of 150Pa; S4: The saturated steam zone of the integrated steam-twisting unit, set at 80℃, is replaced with the saturated steam zone of the integrated steam-twisting unit, set at 82℃; the yarn setting process of steaming at 90℃ and 40% relative humidity for 30 seconds is replaced with the yarn setting process of steaming at 95℃ and 40% relative humidity for 35 seconds. All other steps are the same.

[0039] Comparative Example 1 The preparation method is the same as in Example 1, except that: S1: Plasma activation treatment of cashmere fiber surface is omitted.

[0040] All other steps are the same.

[0041] Comparative Example 2 The preparation method is the same as in Example 1, except that: S3: Replace vacuum sublimation with 80℃ hot air drying for two hours.

[0042] All other steps are the same.

[0043] Comparative Example 3 The preparation method is the same as in Example 1, except that: S3: No water vapor is supplied in the rehumidification section, relative humidity <10%, dry heat at 50℃ for 4 minutes.

[0044] All other steps are the same.

[0045] Comparative Example 4 The process involves blending ordinary cashmere fibers with aerogel-modified polyester fibers: Cashmere, aerogel-modified polyester fibers, and wool are sprayed with wool oil and antistatic agent respectively, left to re-moisten for 20 hours, and then mixed in a ratio of 15:42.5:42.5. The mixture is then carded once using a slow-speed carding machine to obtain a uniform blended cotton lap. The lap is then carded into a sliver at low speed using a semi-worsted spinning process, followed by three draws to form a more uniform sliver. This sliver is then spun into yarn using a spinning machine with a twist of 380, maintaining 75% humidity throughout for antistatic purposes. Finally, the yarn is automatically wound at 600 m / min, and electronic yarn clearing removes thick sections, yielding the cashmere blended yarn.

[0046] Experimental Example 1 The cashmere composite yarns with aerogel shells prepared in Examples 1-3 and Comparative Examples 1-4 were measured: (1) Thermal resistance: The cashmere composite yarn with the aerogel shell was washed continuously for 30 cycles according to the 4N program in GB / T 8629-2017 "Textiles - Test Household Washing and Drying Procedures". The thermal resistance was then measured according to GB / T 11048-2018 "Determination of thermal and moisture resistance of textiles under steady-state conditions for physiological comfort (evaporative hot plate method)". The three-layer sample was covered with a 35℃ hot plate. The ambient temperature was 20℃, the relative humidity was 65%, and the wind speed was ≤0.1m·s. -1 After reaching a steady state, the heating power is recorded, and the thermal resistance is calculated using the formula: thermal resistance = effective area of ​​hot plate × temperature difference between hot and cold surfaces / heating power. The result is then averaged three times.

[0047] (2) Shell density: Gently scrape the aerogel shell-cashmere composite short fibers from the same batch after exiting the channel with a clean blade, collect 10 mg of shell powder, vacuum dry at 105℃ for 2 hours, and then measure the true volume according to the helium specific gravity bottle method (GB / T 31382-2015 "Aerogel Density Test Method"). The density is obtained by dividing the mass by the volume. The target range is 0.16~0.20 g·cm³. -3 .

[0048] (3) Shell retention rate: Take out the channel aerogel shell-cashmere composite short fiber and weigh the initial weight m0. Wash it 30 times with water according to the 4N program of GB / T 8629-2017 "Textiles - Household washing and drying procedures for testing". After vacuum drying, scrape off the surface debris and determine the mass fraction of Si using an inductively coupled plasma atomic emission spectrometer. Calculate the retention rate by comparing it with the Si amount corresponding to m0. The target is ≥90%.

[0049] (4) Single yarn strength: The cashmere composite yarn with the aerogel shell was washed continuously for 30 cycles according to the 4N program in GB / T 8629-2017 "Textiles - Household Washing and Drying Procedures for Test Use". The single yarn breaking strength was then measured at a tensile speed of 500 mm / min, with a clamping distance of 500 mm and a pre-tension of 0.5 cN·tex. -1 Take the average of 10 measurements, with a target value ≥ 280 cN.

[0050] (5) Antibacterial rate: The cashmere composite yarn loaded with the aerogel shell was washed continuously for 30 cycles according to the 4N program in GB / T 8629-2017 "Textiles - Test Household Washing and Drying Procedures". The antibacterial rate was determined according to GB / T 20944.3-2008 "Evaluation of Antibacterial Properties of Textiles". 0.75g was cut and inoculated with 1×10 5 CFU·mL -1 Staphylococcus aureus and Klebsiella pneumoniae, 24±1℃, 150 r·min -1 Shake for 18 hours, then count on plates after elution. Antibacterial rate = (number of colonies in blank control - number of colonies in sample) / number of colonies in blank control × 100%. The blank control is 0.75g of yarn sample that has not undergone any antibacterial treatment but has the same material and structure as the sample. The target antibacterial rate is ≥85%.

[0051] Table 1. Comparison of experimental results between Examples 1-3 and Comparative Examples 1-4 Serial Number Testing items <![CDATA[Thermal resistance (m 2 ·K / W)]]> <![CDATA[Shell density (g / cm 3 ).]]> Shell retention rate (%) Single yarn strength (cN) Antibacterial rate (%) 1 Example 1 0.198±0.002 0.18±0.01 92±2 285±15 90±1 2 Example 2 0.190±0.003 0.16±0.01 90±1 280±10 88±2 3 Example 3 0.200±0.002 0.20±0.01 91±1 283±12 89±1 4 Comparative Example 1 0.145±0.005 0.19±0.01 55±4 275±10 89±1 5 Comparative Example 2 0.142±0.003 0.42±0.01 80±3 265±12 86±2 6 Comparative Example 3 0.185±0.003 0.17±0.01 68±5 280±10 60±3 7 Comparative Example 4 0.145±0.002 0 0 290±10 15±2 The experimental results of Examples 1-3 and Comparative Examples 1-4 are shown in Table 1. Figure 3 As shown, the cashmere composite yarn with an aerogel shell prepared in this invention has a thermal resistance of 0.198m. 2 Due to the preservation of nanopores through flash freezing at -45℃ and vacuum sublimation, the shell density reaches 0.18 g / cm³. 3 Plasma anchoring and steam twisting enable the single yarn to reach a strength of 280 cN, and the quaternary ammonium salt co-condensation achieves an antibacterial rate of 90%. The synergistic effect of these technologies achieves four benefits: lightweight, warmth, washability, and antibacterial properties, making it the optimal embodiment.

[0052] Examples 2 and 3 controlled the thermal resistance of the cashmere composite yarn; the thermal resistance of Example 2 was 0.190 μm. 2 • K / W, thermal resistance of Example 3 is 0.200m 2In terms of K / W, all parameters in Example 2 are at the lower limit of Examples 1-3, the interfacial crosslinking density is slightly lower, and the shell layer may slightly lift after water washing and impact; while the thermal resistance of Example 3 is improved, but there is no significant improvement in any of the indicators, which proves that the thermal resistance value of Example 1 is sufficient to fully reflect the reaction, and there is no need to improve the performance of cashmere composite yarn by increasing the thermal resistance.

[0053] Due to the lack of key technologies, the overall performance of Comparative Examples 1-4 was reduced to varying degrees compared to the Examples. Comparative Example 1 omitted plasma activation treatment, resulting in a sharp drop in surface polar groups and insufficient silane anchoring points. The thermal resistance decreased by 25% compared to Example 1, proving that chemical bonding is a necessary requirement for washability and cannot be replaced by physical adsorption. Comparative Example 2 used hot air drying, which caused a linear increase in thermal resistance and excessive skeleton density, resulting in the loss of low thermal conductivity. Comparative Example 3 omitted rewetting and polycondensation. Due to the lack of water vapor drive, quaternary ammonium salts were released, reducing the antibacterial rate to 60%, and the shell was loose and easily worn. Comparative Example 4 was a blend of ordinary cashmere, lacking an aerogel shell. The antibacterial rate was only 15%, and the thermal resistance improvement rate was 0%, proving that the incremental warmth and antibacterial effect came from the aerogel shell, which in turn proved that the shell is the only source of functional gain.

[0054] In summary, this invention constructs a nano-aerogel shell on the surface of cashmere and co-blends it with aerogel-modified polyester staple fibers to form a dual thermal insulation structure of shell-cashmere + aerogel skeleton, overcoming the bottlenecks of traditional aerogel fibers such as weak interface, poor washability, and poor hand feel. The process uses a technology chain of plasma activation-sol-gel-vacuum phase change-steam twisting to achieve chemical anchoring of the shell, intact nanopores, bonding of antibacterial groups, and crack-free twisting, controlling the yarn's thermal resistance within the range of 0.190~0.200m. 2 • K / W, shell retention rate after 30 washes ≥90%, antibacterial rate ≥88%, single yarn strength ≥280cN. Comparative experiments show that deviation from any key parameter leads to simultaneous deterioration of thermal resistance, shell strength, antibacterial properties, and mechanical properties. This invention provides a washable, antibacterial, and lightweight aerogel yarn solution for functional textiles.

Claims

1. A cashmere composite yarn with an aerogel shell and its preparation method, characterized in that, The preparation method requires first activating cashmere fibers with plasma, performing sol-gel polycondensation and constructing a nano-aerogel shell in situ, then blending them with aerogel-modified polyester staple fibers in a certain proportion, and finally obtaining cashmere composite yarn loaded with aerogel shell through semi-worsted spinning, saturated steam twisting and heat setting.

2. The cashmere composite yarn with an aerogel shell as described in claim 1 and its preparation method, characterized in that, The sol-gel polycondensation is carried out by immersing plasma-activated cashmere short fibers in an oligomeric siloxane-quaternary ammonium salt pregel solution, stirring at a uniform speed and heating to complete the sol-gel polycondensation.

3. The cashmere composite yarn with an aerogel shell as described in claim 1 and its preparation method, characterized in that, The in-situ construction of the nano-aerogel shell involves feeding cashmere short fibers that have completed sol-gel condensation into a freeze-vacuum continuous flow control channel for instantaneous freezing to form a microcrystalline-gel framework, followed by vacuum sublimation, and finally rehydration condensation to obtain the nano-aerogel shell.

4. The cashmere composite yarn with an aerogel shell as described in claim 1 and its preparation method, characterized in that, The saturated steam twisting and heat setting process includes first softening the shell layer appropriately in a saturated steam zone, then performing ring twisting, followed by rapid setting in a dry heat channel to relieve internal stress and stabilize the yarn structure, while taking into account both shell layer integrity and yarn hand feel.

5. The cashmere composite yarn with an aerogel shell as described in any one of claims 1 to 4, and its preparation method, characterized in that, Includes the following steps: S1: Wash the cashmere staple fibers; prepare an oligomeric siloxane-quaternary ammonium salt pregel solution by partially hydrolyzing tetraethoxysilane and methyltriethoxysilane in hydrochloric acid to generate a transparent sol containing siloxane oligomers, then adding (3-trimethoxysilylpropyl)dimethyloctadecylammonium chloride and adjusting the pH to 7.5 to obtain a uniform low-viscosity pregel solution; activate the surface of the cashmere fibers using atmospheric pressure oxygen plasma technology, and then immediately immerse them in the pregel sol for impregnation; S2: After the impregnated cashmere fibers are coated in situ with the pregel solution, the fibers are taken out and placed in a hot air circulating oven at 80°C for 5 minutes and then cured at 120°C for 10 minutes to obtain cashmere short fibers with an antibacterial gel layer on the surface. S3: The gel-coated cashmere short fibers are evenly spread on a perforated stainless steel mesh belt and then sent into a freeze-vacuum continuous flow control channel. First, they enter the instant freezing section, where the temperature in the front area of ​​the channel is -45℃. After the fibers stay for 25 seconds, they are sent into the vacuum sublimation section and stay for 6 minutes. Then, they enter the condensation-rehumidification section, where 50℃ water vapor is added through 0.2mm micropores to maintain the local relative humidity at 55%. The wall temperature is raised to 50℃ and the fibers stay for 4 minutes to obtain the aerogel shell. S4: Aerogel shell-cashmere composite staple fiber is blended with aerogel-modified polyester staple fiber and made into a mixed sliver bundle of 120 strands / sliver by three-pass combing. The sliver bundle is placed in the saturated steam zone of the steam-twisting integrated unit and then ring-spun. After obtaining single yarn, it is steam-set to reduce twist shrinkage. Two single yarns are taken and initially twisted in the Z direction and then re-twisted in the S direction to form a double strand, which is the final product, cashmere composite yarn loaded with aerogel shell layer.

6. The cashmere composite yarn with an aerogel shell as described in claim 5 and its preparation method, characterized in that, The atmospheric pressure oxygen plasma technology described in S1 activates the surface of cashmere fibers under the following conditions: oxygen flow rate of 18-22 L / min, radio frequency power of 90-110 W, and processing time of 1.5-2.5 minutes.

7. The cashmere composite yarn with an aerogel shell as described in claim 5 and its preparation method, characterized in that, The vacuum sublimation section described in S3 has a vacuum level of 100~150Pa.

8. The cashmere composite yarn with an aerogel shell as described in claim 5 and its preparation method, characterized in that, The aerogel shell described in S3 has a shell density of 0.16~0.20 g / cm³. 3 .

9. The cashmere composite yarn with an aerogel shell as described in claim 5 and its preparation method, characterized in that, The saturated steam zone in S4 has a temperature of 78~82℃, and the setting process has a temperature of 85~95℃ and a setting time of 25~35 seconds.

10. The cashmere composite yarn with an aerogel shell as described in claim 5 and its preparation method, characterized in that, The cashmere composite yarn with the aerogel shell described in S4 has a thermal resistance of 0.190~0.200m. 2 ·K / W.

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