Gradient double-phase-change-domain blended spinning seamless temperature-adjusting fabric and preparation method thereof

Abstract

The invention relates to the technical field of intelligent temperature-adjusting textiles, and discloses a gradient double-phase-change-domain blended spinning seamless temperature-adjusting fabric and a preparation method of the gradient double-phase-change-domain blended spinning seamless temperature-adjusting fabric. The temperature adjusting fabric is integrally formed by composite fibers through a seamless weaving technology, and the composite fibers internally comprise a first phase change domain and a second phase change domain which are distributed in a gradient mode in the radial direction. The phase-change temperature of the first phase-change material is 28-32, the phase-change temperature of the second phase-change material is 65-70, the temperature difference between the first phase-change material and the second phase-change material is larger than 30, and the first phase-change material and the second phase-change material correspond to human body resting state and high-temperature processing stability requirements respectively; the phase-change material is blended with a polymer matrix through hydrophobic modification treatment and is stably embedded into fibers, and the surface of the fabric is free of a coating or a microcapsule. The preparation method comprises the following steps: premixing the phase-change material and the polymer matrix, extruding and granulating by using double screws, carrying out double-component melt spinning, stretching and shaping the fibers, and carrying out seamless weaving and forming. The obtained fabric is stable in thermal response wide range, washable, wear-resistant and good in comfort, the heat capacity per unit area reaches 18-25, and the retention rate of the phase change material is larger than 95% after 50 times of standard washing.

Description

Technical Field

[0001] This invention belongs to the field of textile materials and intelligent functional fabrics technology. Specifically, it relates to a gradient two-phase change domain blended spinning seamless temperature-regulating fabric and its preparation method. Background Technology

[0002] With the increasing sophistication of individual thermal and humidity management needs, intelligent temperature-regulating textiles, as an important branch of functional materials, are showing broad application prospects in fields such as sports protection, medical rehabilitation, and special workwear. Introducing phase change materials (PCMs) into fiber or fabric structures, utilizing their solid-liquid phase transition at specific temperatures to absorb or release latent heat, is one of the mainstream technical approaches to achieving dynamic thermal regulation of the human body's microenvironment.

[0003] Currently, existing technical solutions mainly employ surface coating or printing processes to physically attach phase change microcapsules to the fabric surface. For example, patent application CN102534982A discloses a "seamless manufacturing method for intelligent air-conditioned clothing," which attempts to combine phase change heat storage materials with computerized flat knitting seamless knitting technology to achieve temperature regulation by mixing phase change materials into the yarn or performing post-treatment on the fabric surface.

[0004] The aforementioned existing technical solutions have the following main drawbacks: 1. Phase change materials are mainly attached to the fiber surface through physical adsorption or mechanical encapsulation. Under repeated friction, sweat soaking or washing during the wearing process, they are prone to falling off or leaking, resulting in insufficient durability of the product's temperature regulation function.

[0005] 2. Due to limitations in coating or printing processes, phase change materials can only be distributed in localized areas of the fabric, failing to achieve a uniform thermal response across the entire area. Furthermore, constrained by the inherent physical properties of single-phase change materials, their phase change temperature range is typically narrow, generally less than 10°C. It is difficult to match the human body's transition from rest to strenuous exercise. Up to 42 The dynamic range of body temperature changes is insufficient to meet the wide-range temperature regulation requirements in complex environments.

[0006] 3. In order to achieve the temperature regulation function, existing technologies often require the use of multi-layer composite structures or chemical finishing on the fabric surface. This non-integrated structural design not only introduces rigid adhesives or seams, but also destroys the continuous structure between fibers, reducing the softness, elasticity and drape of the fabric, making it difficult to meet the comfort and high extensibility requirements for close-fitting wear.

[0007] While some existing technologies attempt to embed phase change materials (PCMs) into fibers through blend spinning to improve durability, these methods typically use only a single PCM, resulting in a narrow phase change temperature range, usually less than 10°C. It is difficult to cover the human body from a surface temperature of 32 degrees Celsius. In a resting state, the body surface temperature can reach 40 degrees Celsius. The above describes the wide-range temperature changes under intense motion conditions. Furthermore, single-phase change materials, in textile processing, such as heat setting at temperatures typically around 120°C... It is prone to phase change when the temperature is higher than its phase change temperature, which leads to increased material fluidity or even leakage, affecting processing stability and product quality.

[0008] Currently, there is no existing technology that integrates two phase change materials with different phase change temperatures within a single fiber and achieves wide-range thermal regulation through gradient distribution. Therefore, it is necessary to develop a novel temperature-regulating fabric and its preparation method that can simultaneously integrate multiple phase change domains within the fiber, balance low-temperature thermal response and processing stability, and maintain the integrated comfort of the fabric. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the present invention innovatively proposes a gradient two-phase variable domain temperature-regulating fabric and its preparation method.

[0010] The inventive point of this invention is: (1) Two different phase change materials with different phase change temperatures are integrated in a single fiber to form a gradient dual phase change domain structure; (2) The first phase change material (28-32℃) provides resting phase change temperature regulation, while the second phase change material (65-70℃) takes into account both dynamic sensible heat buffering and processing stability; (3) Achieve precise spatial distribution control of the two-phase variable domain through bicomponent spinning technology; (4) Stable encapsulation of phase change materials is achieved through hydrophobic modification and blending technology, with a washability retention rate of >95%.

[0011] In this invention, "gradient distribution" refers to the spatially separated but interface-fused distribution state of the first and second phase change domains on the fiber cross section. A 2-5 micrometer transition region is formed between the two phase change domains through molecular diffusion. In this transition region, the molecular chains of the two polymer matrices diffuse into each other, realizing the physical connection between the core layer and the skin layer.

[0012] In the temperature-regulating fabric, the phase change material is stably embedded in the fiber in a gradient distribution form, forming a composite structure with two different phase change temperature domains. The phase change material is uniformly dispersed in the fiber matrix without macroscopic aggregation. The fiber surface is continuous and intact, without coating or microcapsule attachment traces. The fabric as a whole presents a single homogeneous structure, without seams, composite layers, or local functional areas, maintaining the same softness, elasticity, and close-fitting comfort as conventional knitted fabrics.

[0013] The fabric maintains stable thermal response properties even after repeated washing, friction, and contact with sweat. Its thermoregulation capability covers the range of human body temperature changes from resting to strenuous exercise, and there is no loss of phase change material or functional degradation during long-term use. The phase change temperature of the first phase change material is 28°C. Up to 32 When the human body is at rest, it absorbs or releases latent heat through solid-liquid phase change, buffering fluctuations in body surface temperature; the phase change temperature of the second phase change material is at 65°C. Up to 70 Although it does not undergo a phase change during human movement, as a high-melting-point alkane, it has a high specific heat capacity at this temperature, which can delay the loss of heat to the environment and work together with the first phase change material to achieve a wide-range thermal buffer. At the same time, the high phase change temperature of the second phase change material ensures that it remains stable during textile processing and will not undergo premature phase change or fail due to processing temperature.

[0014] This preparation method involves compounding two phase change materials with different phase change temperatures with a polymer matrix through a blending spinning process. During the spinning process, the spatial distribution of these materials in the fiber cross section is controlled to form a gradient phase change domain structure from the inside out or from the core to the skin. The fabric is then directly formed into a single piece of temperature-regulating fabric using a seamless weaving device.

[0015] The technical solution of the present invention to solve the aforementioned fabric technical problem is to provide a gradient dual-phase change domain temperature regulating fabric, wherein the fabric is integrally formed by composite fibers through a seamless weaving process; the interior of the composite fibers contains a first phase change domain and a second phase change domain, and the first phase change domain and the second phase change domain are distributed in a gradient along the fiber radial direction, that is, the two phase change domains are spatially separated but interface-fused on the fiber cross section. The first phase change domain is composed of a blend of a first phase change material and a first polymer matrix, and the second phase change domain is composed of a blend of a second phase change material and a second polymer matrix; The first and second phase change materials are different organic solid-liquid phase change materials. Their surfaces are hydrophobically modified, preferably using a siloxane coupling agent to ensure good interfacial compatibility with the polymer matrix. The phase change temperature of the first phase change material is 28°C. Up to 32 Corresponding to the body surface temperature at rest, the phase transition temperature of the second phase change material is 65°C. Up to 70 The phase transition temperature difference between the two phase change materials is greater than 30°C. ; The first phase change material has a mass fraction of 15 wt% to 25 wt% in the first phase change domain, and the first polymer matrix has a mass fraction of 75 wt% to 85 wt%, with the sum of their mass fractions being 100%; the second phase change material has a mass fraction of 15 wt% to 25 wt% in the second phase change domain, and the second polymer matrix has a mass fraction of 75 wt% to 85 wt%, with the sum of their mass fractions being 100%. The first phase change material absorbs or releases latent heat through solid-liquid phase change when the human body is at rest, thus buffering temperature fluctuations on the body surface. The second phase change material, while not undergoing phase change during human movement, utilizes its high specific heat capacity to delay heat loss, working in conjunction with the first phase change material to achieve wide-range thermal buffering. Simultaneously, its high phase change temperature ensures stability during processing. The two phase change materials, through gradient distribution, achieve a continuous thermal response from rest to movement. The polymer matrix provides mechanical support and prevents the phase change materials from agglomerating or leaching through good compatibility. The first polymer matrix and the second polymer matrix are the same or well-compatible thermoplastic polymers; The cross-sectional structure of the composite fiber is a core-sheath type. The first phase change domain and the second phase change domain occupy different regions of the fiber cross-section. The two are connected by a molecular diffusion interface. That is, there is no obvious physical boundary between the two phase change domains. Instead, the physical connection is achieved by the mutual diffusion of polymer molecular chains between the two domains to form a transition region. There is no obvious phase separation boundary. That is, when the fiber cross-section is observed with an electron microscope, there is no obvious interface boundary between the two phase change domains, and the structure is continuous. The seamless temperature-regulating fabric is fully knitted using a computerized flat knitting machine or circular knitting machine. That is, the needle bed movement is controlled by a computer to knit a complete fabric including the body, armhole, and neckline in one go, without cutting or sewing. The fabric structure is single-sided plain knit, double-sided rib, or jacquard, without seamless stitching, adhesive layers, or functional patches. The functional consistency error of the entire fabric is less than 5%.

[0016] The technical solutions provided in this application embodiment have at least the following technical effects or advantages: 1. Because this application uses two phase change materials to be blended with the polymer matrix before spinning, and uses bicomponent melt spinning technology to permanently encapsulate them in the internal structure of a single fiber, the phase change materials are physically isolated from the external environment, thus solving the problem of phase change materials falling off and being lost due to friction and washing. After 50 standard washes, the retention rate of phase change materials is greater than 95%, which improves the functional durability and service life of the product.

[0017] 2. Because this application uses two phase change materials with different phase change temperatures, and through a precisely designed spinning assembly, forms a preset and controllable gradient or parallel distribution within the fiber cross-section, it achieves uniform thermal response within the fabric plane and expands the effective temperature range from less than 10°C in traditional methods. Expanded to cover the human body from resting to active states, 32-42 The technical effects over a wide range; the first phase change material in 28-32 Latent heat regulation is provided through solid-liquid phase change. Although the second phase change material does not undergo phase change within this temperature range, its high specific heat capacity can reach 40°C. The left and right sides provide sensible heat buffers, collaboratively solving the limitations of "thermal saturation" or "cold saturation" in materials with a single phase change point, and achieving adaptive adjustment to complex and dynamic thermal environments; the heat capacity per unit area reaches 18-25. .

[0018] 3. Because this application employs a technique that integrates the temperature-regulating function into the fiber body and uses this functional fiber to form a single piece of fabric through a seamless weaving process, it eliminates rigid nodes caused by adhesives, seams, or composite layers, thus preserving the original high elasticity, soft hand feel, and excellent drape of the fabric substrate; the fabric's tensile strength is ≥280. With an elongation at break of ≥45%, it meets the requirements for comfort and high ductility needed for close-fitting wear.

[0019] 4. Since the functional integration is completed in the fiber forming stage of the preparation process of this application, there is no need to rely on subsequent coating or printing finishing processes that may use organic solvents and adhesives. This avoids the emission of volatile organic compounds (VOCs) and chemical residues at the source of production, which is in line with the green and sustainable advanced manufacturing concept, simplifies the production process, and reduces the overall cost.

[0020] 5. Since the phase change temperature of the second phase change material selected in this application is higher than that of textile processing temperature, it ensures that the phase change material will not undergo premature phase change or fail during processing, thus maintaining the stability and consistency of product quality. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the cross-sectional structure of the composite fiber according to an embodiment of the present invention, illustrating the gradient distribution of the first phase change domain and the second phase change domain along the radial direction of the fiber. Specifically: 1 represents the core layer, composed of a blend of a first phase change material and a first polymer matrix (PET) to form the first phase change domain, with the first phase change material having a mass fraction of 15wt% to 25wt%; 2 represents the transition layer, an interface region formed between the core layer and the sheath layer through molecular diffusion, where the molecular chains of the two polymer matrices diffuse into each other, achieving a physical connection between the core layer and the sheath layer; 3 represents the sheath layer, composed of a blend of a second phase change material and a second polymer matrix (PET) to form the second phase change domain, with the second phase change material having a mass fraction of 15wt% to 25wt%. This core-sheath composite structure is integrally formed through a bicomponent spinning process, with the core layer accounting for 40% to 60% of the fiber cross-sectional area and the sheath layer accounting for 40% to 60% of the fiber cross-sectional area. Figure 1 The structure shown corresponds to the core-sheath type composite fiber cross section of Examples 1-3. Figure 1 This is for illustrative purposes only and is not drawn to scale.

[0022] Figure 2 This is a schematic diagram of the process flow of the preparation method of the present invention, which schematically shows the complete process flow from raw material premixing, hydrophobic modification, twin-screw extrusion granulation, two-component melt spinning, fiber cooling, stretching and shaping to seamless weaving. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0024] The phase change material used in this invention is a n-alkane solid-liquid phase change material. Octadectoane and hexadecane are nonpolar alkanes, while the polymer matrix (PET) is a polar polyester. The large difference in interfacial tension between the two leads to poor compatibility when directly blended, easily resulting in phase separation or aggregation during melt spinning. By using a siloxane coupling agent, such as γ-aminopropyltriethoxysilane, surface hydrophobic modification treatment can introduce weakly polar groups compatible with PET onto the surface of the phase change material, reducing interfacial tension, improving the dispersion stability of the phase change material in the polymer matrix, preventing aggregation or exudation during spinning, and preventing loss of the phase change material due to washing and perspiration during fabric use.

[0025] Example 1 This embodiment prepares a gradient two-phase variable domain blended seamless temperature-regulating fabric. The fabric uses a formulation of 20wt% n-octadecane and 20wt% n-hexadecane, with a core-sheath flow rate ratio of 1:1.2 and a double-sided rib weave.

[0026] (a) Raw material specifications The first phase change material is n-octadecane, chemical formula C1. 18 H 38 The first phase change material, CAS number 593-45-3, has a purity ≥99% and a phase change temperature of 28.5℃; the second phase change material is n-hexadecane, chemical formula C2. 36 H 74 The CAS number is 630-06-8, the purity is ≥99%, and the phase transition temperature is 67.3℃. The first polymer matrix and the second polymer matrix are both fiber-grade polyethylene terephthalate (PET), with an intrinsic viscosity of 0.64 dL / g, a melting point of 255-260℃, a glass transition temperature of 75℃, and a melt index of 25 g / 10 min under a load of 2.16 kg at 285℃.

[0027] (II) Preparation method This invention also provides a method for preparing the aforementioned gradient two-phase variable domain blended seamless temperature-regulating fabric, the preparation method of which is as follows: S1: Hydrophobic modification and premixing of phase change materials First, n-octadecane with a purity ≥99% undergoes hydrophobic modification treatment: at 60... γ-aminopropyltriethoxysilane was added at 2% of the mass of n-octadecane, and the mixture was stirred for 2 hours to obtain modified n-octadecane; modified n-hexadecane was prepared by the same method.

[0028] Then, modified n-octadecane and fiber-grade PET chips with an intrinsic viscosity of 0.64 dL / g were added to a first high-speed mixer at a mass ratio of 20:80 and mixed at 800 r / min for 15 min under nitrogen protection to obtain a first premix. At the same time, modified n-hexadecane and PET chips of the same specification were added to a second high-speed mixer at a mass ratio of 20:80 and mixed under the same conditions to obtain a second premix. S2: Twin-screw extrusion granulation The first premix is ​​fed into the first twin-screw extruder, and after five-zone temperature-controlled melt blending, it is extruded and granulated to obtain the first composite masterbatch; the second premix is ​​fed into the second twin-screw extruder, and after the same process, the second composite masterbatch is obtained. The twin-screw extruder has a screw length-to-diameter ratio of 40:1, and the temperature zones are set as follows: Zone 1 240°C. Zone 255 Zone 3, 265 270 in Zone 4 275 in Zone 5 Die head temperature 270 The die head temperature is 5 degrees lower than the screw zone 5 temperature. To reduce the risk of thermal degradation of the melt at the outlet while maintaining sufficient fluidity to avoid pressure fluctuations, the screw speed is 300 r / min, the feed rate is 50 kg / h, the vacuum devouring port pressure is no more than 5 kPa, and the material residence time in the extruder is 2-3 min.

[0029] This temperature gradient design ensures that PET melts gradually while the phase change material remains below its decomposition temperature, with n-octadecane >150°C. hexadecane > 200 Under these conditions, it is fully dispersed in the melt to avoid thermal degradation; S3: Drying of composite masterbatch The first composite masterbatch and the second composite masterbatch were respectively subjected to 60 The fiber is dried in a vacuum drying oven with a vacuum degree of no more than 100 Pa for 8 hours to reduce the moisture content to no more than 50 ppm, so as to avoid the moisture from vaporizing and forming bubbles during the subsequent melt spinning process, which would affect the fiber quality; then it is fed into two independent hoppers of the bicomponent spinning system. S4: Bicomponent melt spinning The bicomponent spinning system includes two single-screw extrusion units, one composite spinning assembly, and a shared spinning tunnel; The first composite masterbatch passes sequentially through five temperature-controlled zones in the first single-screw extrusion unit: Zone 1, preheating zone 245°C. 255 in the second melting zone 265, three-zone homogenization zone 275, front section of the fourth measurement zone 285, the latter part of the fifth measurement zone The screw speed is 60 r / min, the extrusion pressure is 15-20 MPa, and a stable first melt flow is formed; The second composite masterbatch undergoes the same temperature control process in the second single-screw extrusion unit to form a second melt flow; S5: Composite spinning assembly forming The first melt flow and the second melt flow enter the core layer flow channel and the skin layer flow channel of the composite spinning assembly, respectively. The composite spinning assembly is equipped with a conical distribution plate and a concentric annular confluence cavity. By adjusting the speed of the two metering pumps, the ratio of the two melt flow rates is made to 1:1.2, so that the skin layer covers the core layer and is extruded through the Φ0.3 mm irregular spinneret to form the nascent composite fiber. S6: Cooling, stretching, and shaping The nascent composite fibers undergo asymmetric cooling via a side-blowing cooling device at a temperature of 22°C. With a wind speed of 0.5 m / s and a wind direction forming a 60° angle with the fiber axis, this asymmetric cooling method allows the outer layer to crystallize rapidly due to direct exposure to the cooling airflow, while the core layer cools slowly due to being enclosed by the outer layer. This results in a gradient crystallization structure with high crystallinity in the outer layer and relatively low crystallinity in the core layer. This structure enhances the mechanical strength of the outer layer to resist external friction while preserving the proportion of amorphous regions in the core layer, which is beneficial for the crystallization of n-octadecane at 32°C. The surrounding area efficiently absorbs and releases heat.

[0030] Subsequently, the fibers pass through the following stages: - Reverse the oiling roller; - First guide roller; - The second guide roller achieves a spinneret draw ratio of 1.4; - Hot stretching roller assembly: This temperature is between the glass transition temperature and the cold crystallization peak temperature of PET. Stretching at this temperature can enable the PET molecular chain segments to have sufficient mobility to achieve orientation, while avoiding excessive crystallization that could lead to micro-fracture of the phase change material. At the same time, it is beneficial to induce the phase change material to oriented under tensile stress, reduce local thermal resistance differences, and improve the consistency of thermal response. - Heat setting roller assembly: This temperature is close to the cold crystallization temperature of PET, which can stabilize the spatial distribution of the two-phase transformation domains while releasing internal stress, and prevent phase transformation domain migration during subsequent weaving or use; The total stretch ratio during spinning is 2.5, with a spinneret stretch ratio of 1.4 and a post-stretch ratio of 1.8. The winding shrinkage rate is 94%. This parameter combination can balance fiber orientation and the integrity of the phase change material, avoiding the breakage of the phase change domain due to excessive stretching. S7: Seamless weaving The 840 D / 96 f composite fiber tow obtained from winding is directly fed into a fully-fledged computerized flat knitting machine. The machine uses an E24 needle bed, and the yarn tension is controlled at 12. The knitting density is 32 rows / cm in the horizontal direction and 42 rows / cm in the vertical direction. The needle bed movement is controlled by a computer program. The knitting structure is double-sided rib. It is knitted in one piece to form a seamless vest structure, including the body, armholes and neckline, without the need for cutting and sewing. S8: Relaxation treatment Molded fabric at 80 The fabric is relaxed in a hot air circulating oven for 10 minutes to eliminate residual stress in the weaving process. After cooling, the gradient two-phase variable domain temperature-regulating fabric is obtained.

[0031] (III) Product Performance Electron microscopy revealed that the core layer accounted for 45% of the fiber cross-sectional area, while the sheath layer accounted for 55%, consistent with the design objective. There was no clear physical boundary between the two phase transition domains; instead, a 2-5 micrometer transition region was formed through the mutual diffusion of polymer molecular chains between the two domains, resulting in a continuous structure.

[0032] The fabric exhibits a single, homogeneous structure, with no seams, no coatings, and no traces of microcapsule attachment. The fabric surface is continuous and intact, with a functional consistency error of less than 5%.

[0033] Testing revealed that the fabric exhibited a bimodal thermal response within the 32-42℃ range. The enthalpy of phase transition for n-octadecane was 21.1 J / g in the 28-32℃ range, and for n-hexadecane it was 21.4 J / g in the 65-70℃ range, for a total enthalpy of phase transition of 42.5 J / g. The heat capacity per unit area was 22.3 J / (cm²). 2 • K); Differential scanning calorimetry (DSC) was used to test the fabric under a nitrogen atmosphere at a heating rate of 10℃ / min. Endothermic peaks appeared at 32℃ and 67℃, corresponding to the phase transitions of n-octadecane and n-hexadecane, respectively. After 50 standard washes at 40℃ according to AATCC 135 standard, the phase transition enthalpy of the fabric was determined by DSC to be 40.8 J / g, with a phase transition enthalpy retention rate of 96%. The breaking strength was 312 cN, and the breaking elongation was 48%, meeting the softness and elasticity requirements for close-fitting wear.

[0034] Example 2: Optimizing the dynamic thermal response In this embodiment, the ratio of 15wt% of the first phase change material and 25wt% of the second phase change material is used, the core-sheath flow rate ratio is 1:1.5, and the rest of the process is the same as in Embodiment 1; the weaving structure is single-sided plain knit.

[0035] The fabric's heat capacity per unit area was measured to be 24.1 J / (cm²). 2 • K); Differential scanning calorimetry (DSC) was used to test the sample under a nitrogen atmosphere at a heating rate of 10 °C / min. Endothermic peaks appeared at 32 °C and 67 °C, with enthalpies of 18.5 J / g and 26.2 J / g, respectively, and a total phase transition enthalpy of 44.7 J / g. After 50 standard washes at 40 °C according to AATCC 135 standard, the enthalpy was 42.5 J / g, with a retention rate of 95%. The tensile strength was 298 cN, and the elongation at break was 46%. Electron microscopy showed that the core layer accounted for 40% of the cross-sectional area, and the skin layer accounted for 60%.

[0036] This formulation enhances the sensible heat buffering capacity under motion conditions by increasing the content of the second phase change material.

[0037] Example 3: Optimization of Resting-State Thermal Response In this embodiment, the ratio of 25wt% of the first phase change material and 15wt% of the second phase change material is used, the core-sheath flow rate ratio is 1:1.0, and the rest of the process is the same as in Embodiment 1; the weaving structure is a jacquard structure.

[0038] The fabric's heat capacity per unit area was measured to be 23.5 J / (cm²). 2 The sample was tested using differential scanning calorimetry (DSC) at a heating rate of 10 °C / min under a nitrogen atmosphere. Endothermic peaks appeared at 32 °C and 67 °C, with enthalpies of 24.8 J / g and 17.1 J / g, respectively, and a total phase transition enthalpy of 41.9 J / g. After 50 standard washes at 40 °C according to AATCC 135 standard, the enthalpy was 40.6 J / g, with a retention rate of 97%. The tensile strength was 305 cN, and the elongation at break was 47%. Electron microscopy showed that the core layer accounted for 50% of the cross-sectional area, and the skin layer accounted for 50%.

[0039] This formula enhances the phase change temperature regulation capability under resting conditions by increasing the content of the first phase change material.

[0040] Example 1, using a 20wt% formulation, exhibited an enthalpy of 42.5 J / g for phase change, demonstrating optimal overall performance. Example 2, using a 15wt% formulation, achieved an enthalpy of 44.7 J / g for phase change, meeting the mechanical performance requirements. Example 3, using a 25wt% formulation, achieved an enthalpy of 41.9 J / g for phase change and a tensile strength of 305 cN, exhibiting good mechanical properties. These examples fully validated the rationality of the 15-25wt% range. Experimental verification showed that when the phase change material content was below 15wt%, the enthalpy of phase change was too low (<30 J / g), resulting in insignificant temperature regulation; when the phase change material content was above 25wt%, the fiber mechanical properties decreased, with a tensile strength <250 cN, failing to meet the usage requirements.

[0041] Comparative Example 1 verifies the limitations of single-phase change materials. Except for the different phase change material formulation, the polymer matrix (PET), hydrophobic modification treatment, spinning process parameters, and weaving process are the same as in Example 1.

[0042] The fabric was made using a single-component fiber containing only n-octadecane, with the remaining processes the same as in Example 1. The resulting fabric only exhibited a thermal response at 28-32°C, with no temperature regulation capability above 40°C. Furthermore, because the phase change material did not form a double-layer coating structure and was directly exposed on the fiber surface, significant phase change material leaching occurred after washing, resulting in an enthalpy retention rate of only 82%. This indicates that a single phase change domain cannot cover a wide temperature range and has poor durability.

[0043] Comparative Example 2 verifies the limitations of a single high-temperature phase change material. Except for the different phase change material formulation, all other conditions were the same as in Example 1.

[0044] The fabric used was a single-component fiber containing only n-hexadecane. The resulting fabric showed no phase change heat response in the 32-42°C range. Although it had a certain sensible heat buffering capacity, its temperature regulation effect was far inferior to that of Example 1. The enthalpy retention rate after washing was 85%, which was slightly better than that of Comparative Example 1 but still lower than that of Example 1.

[0045] Comparative Example 3 verifies the problem of blended phase change materials. Except for the different phase change material formulation, all other conditions were the same as in Example 1.

[0046] Two phase change materials were blended in the same PET matrix and spun into single-component fibers. Although covering a wide temperature range, the two phase change materials interfered with each other in the same matrix, resulting in decreased crystallinity. Furthermore, phase separation easily occurred during spinning and stretching, leading to uneven micro-region sizes of the phase change materials. Some micro-regions broke during stretching and were significantly lost after washing, resulting in an enthalpy retention rate of only 70%, far lower than the 96% in Example 1. This comparative example illustrates the advantages of a gradient separation structure over a blended structure.

[0047] Comparative Example 4 verifies the advantages of the core-sheath type over the parallel type. Except for the fiber cross-sectional structure, all other conditions were the same as in Example 1.

[0048] The same phase change material ratio as in Example 1 was used, but the fiber cross-sectional structure was a side-by-side type, meaning the first and second phase change domains were distributed side-by-side along the fiber axis. Because both phase change domains in the side-by-side structure are partially exposed on the fiber surface, they are more susceptible to mechanical friction and moisture erosion during washing, leading to phase change material loss and an enthalpy retention rate of only 88%, lower than the 96% of the core-sheath type structure. This comparative example illustrates the protective effect of the sheath layer on the core layer in the core-sheath type structure.

[0049] Application Examples The temperature-regulating fabric described in this invention is particularly suitable for scenarios that require transitions between resting and active states, such as high-intensity interval training (HIIT) apparel.

[0050] In practical applications, when the wearer is at rest and the body surface temperature is close to 32°C, the n-octadecane in the core layer undergoes a solid-liquid phase transition, absorbing excess heat and preventing the body surface temperature from rising further, thus providing a comfortable thermal environment. When the wearer enters a high-intensity exercise phase and the body surface temperature rises to around 40°C, the n-octadecane has completed its phase transition and entered the liquid state, and its sensible heat capacity continues to play a role. At the same time, although the n-hexadecane in the cortex has not reached its 67.3°C phase transition point, as a high-melting-point alkane, it still has a high specific heat capacity (2.2 J / g·K) at 40°C. Furthermore, the cortex structure forms a dense network due to gradient crystallization, which can delay the loss of heat to the environment, working together with the core layer to achieve a wide-range thermal buffer.

[0051] Actual wear tests showed that this fabric can effectively reduce body surface temperature fluctuations by 2-3°C during HIIT training, improving wearing comfort compared to ordinary knitted fabrics.

[0052] Comparison Table of Implementation Examples The table below shows the formulation and performance comparison data of the embodiments and comparative examples of the present invention.

[0053] Note: Except for the phase change material formulation, fiber cross-sectional structure, and core-sheath flow rate ratio, all examples and comparative examples are identical in terms of polymer matrix (PET), hydrophobic modification treatment, spinning process parameters, and weaving process.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gradient two-phase variable domain blended seamless temperature-regulating fabric, characterized in that: The temperature-regulating fabric is formed from composite fibers using a seamless weaving process. The composite fiber contains a first phase transformation domain and a second phase transformation domain, which are distributed in a gradient along the radial direction of the fiber. The first phase change domain is composed of a blend of a first phase change material and a first polymer matrix; The second phase change domain is composed of a blend of a second phase change material and a second polymer matrix; The first phase change material and the second phase change material are different organic solid-liquid phase change materials, which have undergone hydrophobic modification treatment; The first polymer matrix and the second polymer matrix are the same or well-compatible thermoplastic polymers; The first phase change material and the second phase change material have different phase change temperatures, with a phase change temperature difference greater than 30°C. ; The composite fiber has a core-sheath cross-sectional structure, with the first phase change domain located in the core layer and the second phase change domain located in the sheath layer.

2. The temperature-regulating fabric according to claim 1, characterized in that: The phase transition temperature of the first phase change material is 28°C. Up to 32 The phase transition temperature of the second phase change material is 65°C. Up to 70 .

3. The temperature-regulating fabric according to claim 1, characterized in that: The first phase change material is a n-alkanes with 17 to 19 carbon atoms, and the second phase change material is a n-alkanes with 34 to 38 carbon atoms. Both are treated with a siloxane coupling agent to modify their surfaces hydrophobically.

4. The temperature-regulating fabric according to claim 3, characterized in that: The first phase change material is n-octadecane, and the second phase change material is n-hexadecane.

5. The temperature-regulating fabric according to claim 1, characterized in that: Both the first polymer matrix and the second polymer matrix are polyethylene terephthalate, with intrinsic viscosity ranging from 0.60 dL / g to 0.70 dL / g.

6. The temperature-regulating fabric according to claim 1, characterized in that: The first phase change material has a mass fraction of 15 wt% to 25 wt% in the first phase change domain, with the balance being the first polymer matrix; the second phase change material has a mass fraction of 15 wt% to 25 wt% in the second phase change domain, with the balance being the second polymer matrix.

7. The temperature-regulating fabric according to claim 1, characterized in that: The core layer accounts for 40% to 60% of the fiber cross-sectional area, with the remainder being the sheath layer.

8. The temperature-regulating fabric according to claim 7, characterized in that: The first phase transition domain and the second phase transition domain are physically connected through a molecular diffusion interface, with no obvious phase separation boundary.

9. A method for preparing a gradient two-phase variable domain blended seamless temperature-regulating fabric, characterized in that... Includes the following steps: S1. The first phase change material and the second phase change material are respectively treated with hydrophobic modification of siloxane coupling agent at 50°C to 70°C for 1 to 3 hours. Then, the first phase change material and the first polymer matrix, and the second phase change material and the second polymer matrix are respectively premixed at a mass ratio of 15:85 to 25:75 to obtain the first premix and the second premix. S2. The first premixed material is processed by a twin-screw extruder at 240°C. Up to 280 The first composite masterbatch is obtained by melt blending, devolatilization, homogenization and extrusion granulation at a certain temperature; the second premix is ​​processed by the same process to obtain the second composite masterbatch. S3. Dry the first composite masterbatch and the second composite masterbatch respectively until the moisture content is not greater than 100 ppm; S4. Melt the first composite masterbatch and the second composite masterbatch to form a first melt flow and a second melt flow, respectively; S5. The first melt flow and the second melt flow are passed through a composite spinning assembly to form nascent composite fibers; S6. The nascent composite fibers are cooled, oiled, stretched, and heat-set to obtain composite fiber bundles. S7. The composite fiber bundle is formed into a fabric through a seamless weaving process.

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