A layered light weight temperature regulating fabric and method of making the same

Abstract

The present application relates to the field of fabric, provide a kind of layered light temperature-adjusting fabric and preparation method thereof, solve the problem that existing temperature-adjusting fabric cannot consider light and fluffy heat storage, wear resistance, wind resistance and skin-friendly comfort, and phase change microcapsule is not loaded uniformly or not high in load;Including from outside to inside sequentially stacked outer layer, middle layer and inner layer;The outer layer is windproof wear-resistant layer, which is made of dense high-count high-density fabric by shuttle weaving process;The middle layer is three-dimensional fluffy heat storage layer, which is formed by fluffy fluff by electrospinning technology using elastic polyurethane spinning solution and nano-cellulose reinforced phase dispersion solution;The inner layer is skin-friendly temperature-adjusting layer, which is formed by soft knitted fabric woven by weft knitting machine using blended yarn formed by blending viscose fiber coated with phase change microcapsule and cotton fiber;The phase change microcapsule includes core material and wall material, the core material is n-octadecane, and the wall material is urea-formaldehyde resin.

Description

Technical Field

[0001] This invention relates to the field of fabrics, and more particularly to a layered lightweight temperature-regulating fabric and its preparation method. Background Technology

[0002] During the cold season, people's demands for lightweight, warm, and comfortable clothing are constantly increasing, and various fabrics with heat-insulating or temperature-regulating functions have emerged on the market. Existing temperature-regulating fabrics are mostly single-functional layers or simple composite structures, but these fabrics generally suffer from the following problems in practical applications: In the current one-step room-temperature impregnation method, the loading of phase change microcapsules is low and unevenly distributed; direct high-temperature loading easily damages the microcapsule wall material, leading to leakage of the phase change core material; to improve heat insulation, material density or thickness is often increased, sacrificing the fabric's lightweight and softness.

[0003] Chinese Patent Publication No. CN110539536B discloses a lightweight silica aerogel composite thermal insulation fabric and its preparation method. The fabric includes a surface abrasion-resistant protective fabric layer, a middle thermal insulation layer, and an inner comfortable fabric layer. The abrasion-resistant protective fabric layer is made of nylon, the thermal insulation layer is made of silica aerogel / viscose fiber composite material, and the comfortable fabric layer is made of acrylic fiber. By combining techniques such as selecting viscose fibers of specific sizes and modifying the silica aerogel / viscose fiber composite material with carboxyl-containing silane coupling agents, the washability and shrinkage resistance of the composite material are effectively improved, further ensuring the lightweight and thermal insulation effect of the composite fabric. However, this thermal insulation fabric first bonds the surface abrasion-resistant protective fabric layer and the middle thermal insulation layer together with an adhesive, and then bonds the middle thermal insulation layer and the inner comfortable fabric layer together with an adhesive. However, large areas of adhesive can easily clog the pores of the middle layer, reducing air permeability and the bulky heat storage capacity; furthermore, this fabric lacks dynamic temperature regulation capabilities.

[0004] Chinese Patent Publication No. CN114801420A discloses a method for preparing a constant-temperature thermal composite fabric, including the following steps: S1: applying adhesive to the fabric; S2: bonding the base fabric layer; S3: electrostatic adsorption; S4: coating an antibacterial layer; S5: coating a waterproof layer; S6: coating a radiation-proof layer; S7: rolling up the fabric. This invention enables the composite fabric to integrate multiple functions, effectively improving the overall environmental adaptability of the composite fabric. Simultaneously, by utilizing electrostatic adsorption, the entire preparation process is free of lint, ensuring the quality of the fabric. However, the thermal insulation layer of this fabric is obtained by weaving and sewing together the prepared heat-absorbing layer, filling layer, and water-permeable layer. The process is complex and relies on fiber layer stacking to achieve heat storage, resulting in a relatively high thickness that sacrifices the fabric's lightness and softness. Furthermore, the multiple processes using adhesive application followed by bonding reduce the fabric's breathability and fluffiness. Summary of the Invention

[0005] Therefore, in view of the above problems, the present invention provides a layered lightweight temperature-regulating fabric and its preparation method, which solves the problems that existing temperature-regulating fabrics cannot simultaneously achieve lightweight and fluffy temperature storage, wear resistance and windproofness and skin-friendly comfort, as well as uneven or low loading of phase change microcapsules.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A layered lightweight temperature-regulating fabric includes an outer layer, a middle layer, and an inner layer stacked sequentially from the outside to the inside. The outer layer is a windproof and abrasion-resistant layer, which is a dense, high-count, high-density fabric made of polyester filaments through a weaving process. The middle layer is a three-dimensional, fluffy temperature-retaining layer, which is a fluffy sheet formed by electrospinning elastic polyurethane spinning solution and nanocellulose reinforcing phase dispersion liquid. The inner layer is a skin-friendly temperature-regulating layer, which is a soft knitted fabric woven by a weft knitting machine from a blended yarn formed by viscose fiber coated with phase change microcapsules and cotton fiber.

[0008] The elastic polyurethane spinning solution comprises the following raw materials in parts by weight: 80-90 parts of hydroxyl-terminated polyurethane prepolymer, 10-20 parts of epoxy-terminated polyetheramine, 5-10 parts of polyethylene glycol, and 400-450 parts of mixed solvent; the nanocellulose-reinforced phase dispersion comprises the following raw materials in parts by weight: 2-5 parts of bleached hardwood pulp, 0.1-0.25 parts of sodium citrate, 0.5-1 part of polyethylene oxide, and 95-100 parts of deionized water; the phase change microcapsules comprise a core material and a wall material, wherein the core material is n-octadecane and the wall material is urea-formaldehyde resin.

[0009] Hydroxyl-terminated polyurethane (PU) prepolymer serves as the soft segment matrix, providing the fiber with elasticity, flexibility, and resilience in the intermediate layer. The hydroxyl groups provide active sites for subsequent crosslinking reactions. Epoxy-terminated polyetheramine acts as the hard segment crosslinking agent, with the epoxy groups undergoing ring-opening addition reactions with the hydroxyl groups on the surface of the nanocellulose reinforcing phase (CNF), simultaneously enhancing the fiber's mechanical strength and heat resistance. Polyethylene glycol (PEG) not only acts as a phase change heat storage segment, undergoing a solid-liquid phase change during temperature changes to absorb or release latent heat, thus endowing the fiber with dynamic temperature regulation capabilities, but also exhibits good compatibility with PU. The addition of PEG ensures that the hydroxyl-terminated polyurethane prepolymer is uniformly dispersed in the matrix. In the elastic polyurethane spinning solution, the hydroxyl-terminated polyurethane prepolymer provides skeletal elasticity, PEG embeds into the PU segments to form phase change heat storage functionality, and the epoxy-terminated polyetheramine forms chemical bonds with CNF during subsequent UV crosslinking, improving network stability.

[0010] CNF was extracted from bleached hardwood pulp as a reinforcing phase; sodium citrate was added as a dispersant to inhibit CNF agglomeration through charge shielding and steric hindrance; polyethylene oxide was added as a high-molecular-weight spinning aid to improve the viscoelasticity and fiber-forming properties of the CNF dispersion and prevent the formation of beads or broken fibers during electrospinning; the CNF surface is rich in hydroxyl groups, which can form hydrogen bonds and chemical crosslinks with the epoxy groups of PU to construct an interpenetrating network of PU fibers and CNF reinforcing fibers.

[0011] Furthermore, the mass ratio of viscose fiber to cotton fiber in the blended yarn is 7:3.

[0012] Furthermore, the mixed solvent is a mixed solution of N,N-dimethylacetamide and N-methylpyrrolidone, wherein the volume ratio of N,N-dimethylacetamide to N-methylpyrrolidone is 3-5:1.

[0013] Furthermore, the preparation process of the elastic polyurethane spinning solution is as follows: hydroxyl-terminated polyurethane prepolymer and epoxy-terminated polyetheramine are dissolved in a mixed solvent according to the weight parts, polyethylene glycol is added, and the mixture is sheared and stirred at a speed of 10000r / min-15000r / min for 30min-45min at room temperature to ensure that all components are fully dissolved and mixed evenly, thereby obtaining the elastic polyurethane spinning solution.

[0014] Furthermore, the preparation process of the nanocellulose-reinforced phase dispersion is as follows: cellulose nanofibers are extracted from bleached hardwood pulp using sulfuric acid hydrolysis to obtain a cellulose nanofiber suspension. Deionized water is added to the cellulose nanofiber suspension, and after stirring evenly, sodium citrate and polyethylene oxide are added as dispersants. The mixture is then subjected to ultrasonic treatment and static defoaming to obtain the nanocellulose-reinforced phase dispersion.

[0015] The method for preparing the layered lightweight temperature-regulating fabric described above includes the following steps:

[0016] S1. Preparation of outer layer: The outer layer is obtained by using polyester filaments to make a dense high-count high-density fabric with a warp density of 100-140 threads / 10cm and a weft density of 80-120 threads / 10cm through a weaving process.

[0017] S2. Preparation of the intermediate layer: The intermediate layer is prepared in a multi-nozzle electrospinning device, which includes a first nozzle and a second nozzle. Elastic polyurethane spinning solution is injected into the first nozzle, and nanocellulose reinforcing phase dispersion is injected into the second nozzle. The multi-nozzle electrospinning device is started to spin synchronously. A high-voltage electrostatic field is used to cause the elastic polyurethane spinning solution sprayed from the first nozzle to form continuous polyurethane fibers, and the nanocellulose reinforcing phase dispersion sprayed from the second nozzle to form nanocellulose reinforcing fibers. The two types of fibers are deposited on a receiving roller to form a composite fiber web in which continuous polyurethane fibers and nanocellulose reinforcing fibers are initially interpenetrated. The composite fiber web is then placed in an ultraviolet curing chamber to achieve in-situ chemical cross-linking between the fibers. Finally, the composite fiber web undergoes supercritical carbon dioxide foaming treatment to obtain the intermediate layer.

[0018] S3. Preparation of inner layer: Viscose fiber coated with phase change microcapsules is blended with cotton fiber into yarn, and then knitted into soft knitted fabric using a weft knitting machine to obtain the inner skin-friendly temperature-regulating layer.

[0019] S4. The outer layer, middle layer, and inner layer are positioned and bonded together using dotted hot melt adhesive or stitching, and then heat-set to obtain a layered lightweight temperature-regulating fabric.

[0020] In the UV curing chamber, in-situ chemical cross-linking between fibers is achieved. The epoxy groups in PU undergo ring-opening addition reactions with the hydroxyl groups on the CNF surface to form covalent bonds. Hydrogen bond networks are formed between PU segments and between PU and CNF. After supercritical carbon dioxide foaming treatment, supercritical CO2 penetrates into the fiber interior and inter-fiber pores, playing a role in plasticization and expansion. When the pressure is released, CO2 rapidly vaporizes and escapes, forming micron-sized pores inside and between the fibers. A large amount of still air is locked in the pores, significantly reducing thermal conductivity and improving thermal insulation. The elasticity of PU ensures that the pore structure rebounds after compression, maintaining its fluffiness. The CNF reinforcing phase maintains structural stability and is not prone to collapse during long-term use.

[0021] Winter temperatures fluctuate greatly, often ranging from 0℃ to 10℃ or even lower outdoors, while indoor or enclosed spaces (such as vehicle compartments or heated indoor environments) can reach 18℃ to 25℃ or higher. Human skin temperature, whether at rest or in motion, is generally 33℃ to 38℃. The layered, lightweight, temperature-regulating fabric prepared using this technology exhibits significant adaptability and advantages in winter applications. The inner layer of the fabric uses viscose fiber coated with n-octadecane phase-change microcapsules. Octadecane has a melting point of approximately 28℃ to 30℃ and a high latent heat (approximately 20 KJ / Kg), allowing for a solid-liquid phase transition when the ambient or body surface temperature crosses this range.

[0022] When moving from cold to hot (such as from a cold outdoor environment to a warm indoor environment or when body temperature rises during exercise), microcapsules absorb and store excess heat, slowing down the rise in body surface temperature, reducing stuffiness and sweating, and avoiding damp and cold discomfort.

[0023] When transitioning from heat to cold (such as stopping activity or returning to a cold environment), the microcapsules release stored heat, slowing the drop in body surface temperature and improving thermal comfort and cold protection.

[0024] Since the temperature regulation effect of phase change microcapsules is mainly reflected in the buffering of temperature fluctuations, their heat preservation effect is limited when the temperature is continuously low (<20℃) and the temperature difference is insufficient to trigger a phase change. Therefore, this invention combines them with a three-dimensional, fluffy heat storage intermediate layer. This intermediate layer is formed by electrospinning, in-situ crosslinking, and supercritical foaming of elastic polyurethane and nanocellulose reinforcement phase to create a high-porosity structure that can lock in a large amount of still air, significantly reduce heat conduction, and achieve long-term static heat preservation. The outer layer of dense, high-count polyester woven fabric effectively blocks the intrusion of cold wind and improves wind resistance and abrasion resistance.

[0025] Furthermore, the preparation process of the viscose fiber coated with phase change microcapsules is as follows:

[0026] I. Wet fibers with a moisture content of 40%-50% are obtained by wet spinning and pre-stretching of viscose fiber dope solution;

[0027] II. Immerse the wet fiber in anhydrous ethanol at a mass ratio of 1:10-12, let it stand at 25°C for 20-30 minutes, change the liquid every 5 minutes, and obtain ethanol gel fiber after water replacement.

[0028] III. Disperse the phase change microcapsules and nanocellulose whiskers in anhydrous ethanol at a mass ratio of 4-5:1 to prepare a microcapsule suspension with a solid content of 10%-15%, and sonicate for 30 minutes.

[0029] IV. The ethanol gel fiber obtained in step II is passed through a dual-temperature zone at a speed of 0.5 m / min and placed in a loading bath in the microcapsule suspension. The dual-temperature zone includes a first temperature zone and a second temperature zone. The temperature of the first temperature zone is 25°C, and the temperature of the second temperature zone is 45°C. The microcapsule loading in the first temperature zone is 5%-10%, and the microcapsule loading in the second temperature zone is 25%-35%.

[0030] V. After the ethanol gel fiber treated in the loading bath is wrapped with filter paper, it is dried at 80℃ for 15min-20min to remove residual ethanol and obtain viscose fiber coated with phase change microcapsules.

[0031] Among them, viscose fiber dope is obtained by spinning through alkalized cellulose xanthate solution. Wet spinning involves extruding the dope into an acidic coagulation bath, where cellulose is regenerated and nascent fibers are formed. Pre-stretching involves applying mechanical stretching to the fiber while it is still in a plastic state, causing the fiber macromolecular chains to orient along the axial direction, thereby improving the fiber strength and modulus. At this time, the wet fiber structure is relatively open, with a large number of micropores and capillaries inside, which facilitates rapid penetration and gelation when ethanol replaces water in the subsequent process.

[0032] Taking advantage of the fact that ethanol is miscible with water and can form hydrogen bonds with the polar groups inside viscose fibers, water in the fiber pores and capillaries is gradually replaced with ethanol to form ethanol gel fibers. Multiple liquid changes are made to completely remove water and prevent phase separation or aggregation of water with the subsequent microcapsule suspension. The ethanol gel fiber maintains a certain degree of flexibility and structural integrity, but the internal hydrogen bond network is partially occupied by ethanol molecules, which is conducive to the more uniform diffusion of microcapsules into the fiber pores in the loading bath.

[0033] The CNC nanofiber whiskers possess a high aspect ratio and abundant hydroxyl groups, enabling them to form a stable three-dimensional network in ethanol. This network acts as an anti-agglomeration framework, preventing microcapsules from settling or adhering to each other in the suspension. The first temperature zone is 25°C. At this low temperature, the microcapsule surface viscosity is high, and adsorption is mainly on the fiber surface, resulting in a low loading capacity. This ensures that the microcapsules form an initial anchor on the fiber surface, avoiding direct impact from high temperatures that could cause the capsule wall to rupture. The second temperature zone is 45°C, close to the liquefaction initiation temperature of the phase change material (e.g., octadecane melting point 28°C-30°C). The microcapsule surface softens slightly, and the ethanol viscosity decreases, making it easier for the microcapsules to enter and be captured within the fiber pores. At this point, the loading capacity increases, achieving dual encapsulation of the phase change microcapsules on both the surface and inside the viscose fiber. The segmented loading in the two temperature zones avoids capsule wall damage or fiber structure destruction caused by a single high-temperature, high-load loading.

[0034] By adopting the aforementioned technical solution, the beneficial effects of the present invention are as follows:

[0035] (1) The layered lightweight temperature-regulating fabric prepared by this technical solution has a multi-layer composite structure. The outer layer is a dense, high-count, high-density polyester filament woven fabric, which effectively blocks the intrusion of external cold wind and improves windproof and wear-resistant properties. The middle layer is a three-dimensional, fluffy temperature-storing layer, which forms a high-porosity, high-elasticity temperature-storing air layer, which can significantly reduce heat conduction and achieve long-term heat preservation. The inner layer is a skin-friendly temperature-regulating layer, and the phase change microcapsules can absorb or release heat when the external temperature changes. This multi-layer composite structure can simultaneously achieve windproof, temperature-storing, dynamic temperature regulation, and skin-friendly comfort in cold or temperature difference environments. The overall fabric is lightweight, soft, easy to fold and store, and convenient for use in various scenarios such as outdoor, sports, and protection.

[0036] (2) The n-octadecane phase change microcapsules were coated on the surface and internal pores of viscose fiber. The high permeability of the ethanol gel fiber was combined with the dual-temperature segmented loading method, which allowed the microcapsules to penetrate deep into the fiber and be evenly distributed on the surface. The loading amount was significantly higher than that of the one-step room temperature impregnation method.

[0037] (3) Use dotted hot melt adhesive or stitch positioning method to composite the outer layer, middle layer and inner layer, which avoids the full coverage adhesive layer blocking the pores of the middle layer and ensures that the layers are not easy to peel off. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the layered lightweight temperature-regulating fabric in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram illustrating the formation of fluffy flocculent material in an embodiment of the present invention;

[0040] The labels in the diagram are as follows: 1-outer layer, 2-middle layer, 3-inner layer, 21-first nozzle, 22-second nozzle, 201-polyurethane fiber, 202-nanocellulose reinforcing fiber. Detailed Implementation

[0041] Example 1

[0042] refer to Figure 1 A layered lightweight temperature-regulating fabric includes an outer layer 1, a middle layer 2, and an inner layer 3 stacked sequentially from the outside to the inside. The outer layer 1 is a windproof and abrasion-resistant layer, which is a dense, high-count, high-density fabric made of polyester filaments through a weaving process. The middle layer 2 is a three-dimensional, fluffy temperature-retaining layer, which is a fluffy sheet formed by electrospinning elastic polyurethane spinning solution and nanocellulose reinforcing phase dispersion solution. The inner layer 3 is a skin-friendly temperature-regulating layer, which is a soft knitted fabric woven by a weft knitting machine from a blended yarn formed by blending viscose fiber coated with phase change microcapsules and cotton fiber.

[0043] The polyester filament is a cross-section polyester filament with a single filament linear density of 55 dtex, a warp density of 120 threads / 10cm, a weft density of 100 threads / 10cm, and a woven weight of 180g / m. 2 Dense, high-count, high-density fabric;

[0044] The elastic polyurethane spinning solution comprises the following raw materials in parts by weight: 85 parts hydroxyl-terminated polyurethane prepolymer, 12 parts epoxy-terminated polyetheramine, 8 parts polyethylene glycol, and 420 parts mixed solvent; the nanocellulose-reinforced phase dispersion comprises the following raw materials in parts by weight: 3 parts bleached hardwood pulp, 0.15 parts sodium citrate, 0.8 parts polyethylene oxide, and 96 parts deionized water; the phase change microcapsules comprise a core material and a wall material, wherein the core material is n-octadecane and the wall material is urea-formaldehyde resin.

[0045] The polyethylene glycol has a molecular weight of 1500; the mass ratio of viscose fiber to cotton fiber in the blended yarn is 7:3; the mixed solvent is a mixed solution of N,N-dimethylacetamide and N-methylpyrrolidone, and the volume ratio of N,N-dimethylacetamide and N-methylpyrrolidone is 3:1.

[0046] The preparation process of the elastic polyurethane spinning solution is as follows: hydroxyl-terminated polyurethane prepolymer and epoxy-terminated polyetheramine are dissolved in a mixed solvent according to the weight parts, polyethylene glycol is added, and the mixture is sheared and stirred at a speed of 12000 r / min for 30 min at room temperature to ensure that all components are fully dissolved and mixed evenly to obtain the elastic polyurethane spinning solution.

[0047] The preparation process of the nanocellulose-reinforced phase dispersion is as follows: cellulose nanofibers are extracted from bleached hardwood pulp by sulfuric acid hydrolysis to obtain a cellulose nanofiber suspension. Deionized water is added to the cellulose nanofiber suspension, and after stirring evenly, sodium citrate and polyethylene oxide are added as dispersants. The mixture is then subjected to ultrasonic treatment and static defoaming to obtain the nanocellulose-reinforced phase dispersion.

[0048] refer to Figure 2 The preparation method of the layered lightweight temperature-regulating fabric described above includes the following steps:

[0049] S1. Preparation of outer layer: The outer layer is obtained by using polyester filaments to make a dense high-count high-density fabric with a warp density of 120 threads / 10cm and a weft density of 100 threads / 10cm through a weaving process.

[0050] S2. Preparation of the intermediate layer: The intermediate layer 2 is prepared in a multi-nozzle electrospinning device, which includes a first nozzle 21 and a second nozzle 22. Elastic polyurethane spinning solution is injected into the first nozzle 21, and nanocellulose reinforcing phase dispersion is injected into the second nozzle 22. The multi-nozzle electrospinning device is started to spin synchronously. A high-voltage electrostatic field is used to cause the elastic polyurethane spinning solution sprayed from the first nozzle 21 to form continuous polyurethane fibers 201, and the nanocellulose reinforcing phase dispersion sprayed from the second nozzle 22 to form nanocellulose reinforcing fibers 202. The two types of fibers are deposited on a receiving roller to form a composite fiber web in which continuous polyurethane fibers and nanocellulose reinforcing fibers initially interpenetrate. The composite fiber web is then placed in an ultraviolet curing chamber to achieve in-situ chemical cross-linking between the fibers. Finally, the composite fiber web undergoes supercritical carbon dioxide foaming treatment to obtain the intermediate layer 2.

[0051] S3. Preparation of inner layer: Viscose fiber coated with phase change microcapsules is blended with cotton fiber into yarn, and then knitted into soft knitted fabric using a weft knitting machine to obtain the inner skin-friendly temperature-regulating layer.

[0052] S4. The outer layer, middle layer and inner layer are positioned and laminated with dotted hot melt adhesive and then heat-set to obtain a layered lightweight temperature-regulating fabric.

[0053] The propulsion speed of the first nozzle is 1.0 mL / h; the propulsion speed of the second nozzle is 0.3 mL / h; the voltage of the high-voltage electrostatic field is set to 16 kV, the receiving distance is 18 cm, and the drum rotation speed is 80 r / min;

[0054] The conditions for in-situ chemical crosslinking are: wavelength 365 nm, light intensity 5 mW / cm². 2 10 minutes;

[0055] The supercritical carbon dioxide foaming treatment was performed with a pressure of 12 MPa, a temperature of 45°C, and a time of 40 min.

[0056] The preparation process of the viscose fiber coated with phase change microcapsules is as follows:

[0057] I. Wet fibers with a moisture content of 40% are obtained by wet spinning and pre-stretching of viscose fiber dope solution;

[0058] II. Immerse the wet fiber in anhydrous ethanol at a mass ratio of 1:10, let it stand at 25°C for 30 minutes, change the liquid every 5 minutes, and obtain ethanol gel fiber after water replacement.

[0059] III. Disperse the phase change microcapsules and nanocellulose whiskers CNC in anhydrous ethanol at a mass ratio of 4:1 to prepare a microcapsule suspension with a solid content of 10%, and sonicate for 30 minutes.

[0060] IV. The ethanol gel fiber obtained in step II is passed through a dual-temperature zone at a speed of 0.5 m / min and placed in a loading bath in the microcapsule suspension. The dual-temperature zone includes a first temperature zone and a second temperature zone. The temperature of the first temperature zone is 25°C, and the temperature of the second temperature zone is 45°C. The microcapsule loading in the first temperature zone is 5%, and the microcapsule loading in the second temperature zone is 25%.

[0061] V. After the ethanol gel fiber treated with the loading bath is wrapped with filter paper, it is dried at 80°C for 15 min to remove residual ethanol and obtain viscose fiber coated with phase change microcapsules.

[0062] The preparation process of the phase change microcapsules is as follows:

[0063] a. Take n-octadecane as the phase change core material, heat it in a 60°C water bath until it is completely melted, and form a homogeneous liquid for later use;

[0064] b. Add urea and formaldehyde to a reaction vessel at a molar ratio of 1:1.5, and stir at 60°C for 30 minutes to obtain a transparent urea-formaldehyde prepolymer solution.

[0065] c. Adjust the pH of the urea-formaldehyde prepolymer solution to 7.5. In a high-speed shear emulsifier, slowly add the homogeneous liquid to the preheated urea-formaldehyde prepolymer solution and shear emulsify at 5000 r / min for 5 minutes to form a stable O / W type emulsion, wherein the n-octadecane droplets are the core material and the urea-formaldehyde prepolymer is the wall material precursor. Continue stirring and reacting at 60°C for 2 hours to allow the urea-formaldehyde prepolymer to undergo a condensation reaction on the surface of the oil droplets, gradually forming a continuous urea-formaldehyde resin wall film that encapsulates the n-octadecane droplets, thus obtaining the primary product of phase change microcapsules.

[0066] d. Heat the reaction system to 80℃ and continue to keep it warm for 2 hours to further cross-link and cure the urea-formaldehyde resin wall film. After the reaction is completed, cool the product to room temperature, separate the solid microcapsules by centrifugation, wash them repeatedly with deionized water 3 times, place the washed microcapsules in a vacuum drying oven, and dry them for 12 hours at 50℃ and a vacuum degree of 0.08MPa to obtain phase change microcapsules.

[0067] Example 2

[0068] The difference from Comparative Example 1 is that the propulsion speed of the first nozzle is 0.9 mL / h; the propulsion speed of the second nozzle is 0.35 mL / h; the receiving distance is 15 cm, increasing the fiber interlacing density. Other technical solutions are the same as in Example 1.

[0069] Example 3

[0070] The difference from Comparative Example 1 is:

[0071] In the preparation process of the viscose fiber coated with phase change microcapsules: in step IV, the loading amount in the dual-temperature zone loading bath is maintained at 5% in the first temperature zone and the loading amount in the second temperature zone is increased to 35%. Other technical solutions are the same as in Example 1.

[0072] Comparative Example 1

[0073] The difference from Comparative Example 1 is that the intermediate layer uses ordinary polyester staple fiber wadding. Other technical solutions are the same as in Example 1.

[0074] The intermediate and inner layers prepared in Examples 1 to 3 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 1.

[0075] Table 1

[0076]

[0077] Thermal conductivity: Tested using a TPS2500S thermal constant analyzer.

[0078] Phase transition enthalpy: Tested using differential scanning calorimetry.

[0079] Looseness: Calculated by bulk density, as shown in equation (1):

[0080] (1)

[0081] In the formula, M is the weight of the fluffy lint in mg, and V is the volume of the fluffy lint in cm³. 3 .

[0082] Moisture permeability: The moisture permeability of the fluffy wadding was measured using the positive cup method according to GB / T 12704.

[0083] As can be seen from the test results in Table 1, the intermediate layer fluffy wadding prepared by this technical solution has a lower thermal conductivity than the ordinary polyester short fiber wadding in Comparative Example 1, indicating that the fluffy structure effectively reduces heat conduction and has better thermal insulation performance.

[0084] In Example 3, the loading of the inner phase change microcapsules was increased by segmented loading in a dual-temperature zone, and the phase change enthalpy was 31.2 J / g, which was higher than that of other samples, indicating that its temperature regulation capability was stronger.

[0085] The lower the bulk density, the fluffier the intermediate layer wadding, the more still air it can trap, reducing the total thermal conductivity of the wadding and thus facilitating heat dissipation and improving insulation performance. The intermediate layer wadding prepared by this technical solution has a lower bulk density than the ordinary polyester short fiber wadding in Comparative Example 1, indicating that the intermediate layer of this invention is lighter, fluffier, has more pores, and a thicker heat-storing air layer.

[0086] The moisture permeability of Examples 1 to 3 is lower than that of Comparative Example 1. This is because the fluffy structure of the middle layer of the present invention locks in the air while moderately reducing the direct permeability rate of water vapor, thus taking into account both heat preservation and moisture management.

[0087] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art will understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A layered lightweight temperature-regulating fabric, characterized in that: It includes an outer layer, a middle layer, and an inner layer stacked sequentially from the outside to the inside; the outer layer is a windproof and wear-resistant layer, which is a dense, high-count, high-density fabric made of polyester filaments through a weaving process; the middle layer is a three-dimensional, fluffy, and heat-retaining layer, which is a fluffy sheet formed by electrospinning elastic polyurethane spinning solution and nano-cellulose reinforcing phase dispersion liquid; the inner layer is a skin-friendly and temperature-regulating layer, which is a soft knitted fabric woven by a weft knitting machine from blended yarns formed by blending cotton fibers and viscose fibers coated with phase change microcapsules. The raw materials for preparing the elastic polyurethane spinning solution include: 80-90 parts of hydroxyl-terminated polyurethane prepolymer, 10-20 parts of epoxy-terminated polyetheramine, 5-10 parts of polyethylene glycol, and 400-450 parts of mixed solvent; the raw materials for preparing the nanocellulose-reinforced phase dispersion include: 2-5 parts of bleached hardwood pulp, 0.1-0.25 parts of sodium citrate, 0.5-1 part of polyethylene oxide, and 95-100 parts of deionized water; the phase change microcapsules include a core material and a wall material, wherein the core material is n-octadecane and the wall material is urea-formaldehyde resin.

2. The layered lightweight temperature-regulating fabric according to claim 1, characterized in that: The mass ratio of viscose fiber to cotton fiber in the blended yarn is 7:

3.

3. The layered lightweight temperature-regulating fabric according to claim 1, characterized in that: The mixed solvent is a mixed solution of N,N-dimethylacetamide and N-methylpyrrolidone, wherein the volume ratio of N,N-dimethylacetamide to N-methylpyrrolidone is 3-5:

1.

4. The layered lightweight temperature-regulating fabric according to claim 1, characterized in that, The preparation process of the elastic polyurethane spinning solution is as follows: hydroxyl-terminated polyurethane prepolymer and epoxy-terminated polyetheramine are dissolved in a mixed solvent according to the weight parts, polyethylene glycol is added, and the mixture is sheared and stirred at a speed of 10000r / min-15000r / min for 30min-45min at room temperature to ensure that all components are fully dissolved and mixed evenly, thereby obtaining the elastic polyurethane spinning solution.

5. The layered lightweight temperature-regulating fabric according to claim 1, characterized in that, The preparation process of the nanocellulose-reinforced phase dispersion is as follows: cellulose nanofibers are extracted from bleached hardwood pulp by sulfuric acid hydrolysis to obtain a cellulose nanofiber suspension. Deionized water is added to the cellulose nanofiber suspension, and after stirring evenly, sodium citrate and polyethylene oxide are added as dispersants. The mixture is then subjected to ultrasonic treatment and static defoaming to obtain the nanocellulose-reinforced phase dispersion.

6. The method for preparing the layered lightweight temperature-regulating fabric according to claim 1, characterized in that, Includes the following steps: S1. Preparation of outer layer: The outer layer is obtained by using polyester filaments to make a dense high-count high-density fabric with a warp density of 100-140 threads / 10cm and a weft density of 80-120 threads / 10cm through a weaving process. S2. Preparation of the intermediate layer: The intermediate layer is prepared in a multi-nozzle electrospinning device, which includes a first nozzle and a second nozzle. Elastic polyurethane spinning solution is injected into the first nozzle, and nanocellulose reinforcing phase dispersion is injected into the second nozzle. The multi-nozzle electrospinning device is started to spin synchronously. A high-voltage electrostatic field is used to cause the elastic polyurethane spinning solution sprayed from the first nozzle to form continuous polyurethane fibers, and the nanocellulose reinforcing phase dispersion sprayed from the second nozzle to form nanocellulose reinforcing fibers. The two types of fibers are deposited on a receiving roller to form a composite fiber web in which continuous polyurethane fibers and nanocellulose reinforcing fibers are initially interpenetrated. The composite fiber web is then placed in an ultraviolet curing chamber to achieve in-situ chemical cross-linking between the fibers. Finally, the composite fiber web undergoes supercritical carbon dioxide foaming treatment to obtain the intermediate layer. S3. Preparation of inner layer: Cotton fiber is blended with viscose fiber coated with phase change microcapsules to form yarn, and then knitted into soft knitted fabric using a weft knitting machine to obtain the inner skin-friendly temperature-regulating layer. S4. The outer layer, middle layer, and inner layer are positioned and bonded together using dotted hot melt adhesive or stitching, and then heat-set to obtain a layered lightweight temperature-regulating fabric.

7. The method for preparing the layered lightweight temperature-regulating fabric according to claim 6, characterized in that, The preparation process of the viscose fiber coated with phase change microcapsules is as follows: I. Wet fibers with a moisture content of 40%-50% are obtained by wet spinning and pre-stretching of viscose fiber dope solution; II. Immerse the wet fiber in anhydrous ethanol at a mass ratio of 1:10-12, let it stand at 25°C for 20-30 minutes, change the liquid every 5 minutes, and obtain ethanol gel fiber after water replacement. III. Disperse the phase change microcapsules and nanocellulose whiskers in anhydrous ethanol at a mass ratio of 4-5:1 to prepare a microcapsule suspension with a solid content of 10%-15%, and sonicate for 30 minutes. IV. The ethanol gel fiber obtained in step II is passed through a dual-temperature zone at a speed of 0.5 m / min and placed in a loading bath in the microcapsule suspension. The dual-temperature zone includes a first temperature zone and a second temperature zone. The temperature of the first temperature zone is 25°C, and the temperature of the second temperature zone is 45°C. The microcapsule loading in the first temperature zone is 5%-10%, and the microcapsule loading in the second temperature zone is 25%-35%. V. After the ethanol gel fiber treated in the loading bath is wrapped with filter paper, it is dried at 80℃ for 15min-20min to remove residual ethanol and obtain viscose fiber coated with phase change microcapsules.

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