A three-layer covered yarn and its preparation method

Abstract

This application provides a three-layer covered yarn and its preparation method. The three-layer covered yarn consists of an inner layer, a middle layer, and an outer layer; wherein, the inner layer material is composed of hollow fibers with a hollowness ratio of 20-50%; the middle layer material is composed of conductive fibers, wherein the conductive fibers are fibers with a conductive component coated on their surface; the conductive component is a mixture of NTC thermistor material and conductive silver paste; the outer layer material is composed of irregularly shaped cross-section fibers. The three-layer covered yarn combines high-efficiency conductivity, active moisture absorption and perspiration wicking, and high-precision body temperature sensing functions, and can be used as a core functional material for smart wearable textiles. The preparation method of the three-layer covered yarn can adopt a dynamic thermal management process to achieve a simplified production process and efficient integration between functional layers.

Description

Technical Field

[0001] This invention belongs to the field of textile materials, specifically relating to a three-layer covered yarn and its preparation method, and more particularly to a three-layer covered yarn and its preparation method that combines high-efficiency conductivity, active moisture absorption and perspiration wicking and high-precision body temperature sensing functions. Background Technology

[0002] With the rapid development of smart wearable technology, smart wearable textiles are evolving from single-function to multi-functional integration. However, in achieving multi-functional integration, many technical bottlenecks still need to be overcome. Ideal smart wearable textiles not only need to possess multiple functions such as conductivity, sensing, and moisture and heat management, but also must take into account both good wearing comfort and long-term durability.

[0003] Currently, traditional yarns generally suffer from the problem of mutual constraints between different properties in terms of functional integration. For example, to impart conductivity to yarns, dense metal coatings or carbon-based materials are often used as conductive layers. However, these dense structures often hinder the yarn's moisture absorption and breathability, leading to heat and moisture buildup and affecting wearing comfort. On the other hand, traditional moisture-wicking fibers (such as polypropylene and aramid) are mostly insulating materials, making it difficult to simultaneously achieve conductivity and moisture management functions. Existing multifunctional yarns mostly adopt blended or simple core-sheath structures, which generally suffer from problems such as mutual interference between functional components, rapid performance degradation, insufficient durability, and limited sensing accuracy. Therefore, how to efficiently integrate multiple functions into a single yarn and effectively coordinate the compatibility and synergy between these functions has become a key challenge that urgently needs to be solved in this technical field.

[0004] Therefore, it is necessary to develop a new type of multifunctional yarn. Summary of the Invention

[0005] This application aims to provide a three-layer covered yarn and its preparation method, which can be applied to the field of smart wearable textiles and can achieve multiple functions such as high-efficiency conductivity, active moisture absorption and perspiration wicking, and high-precision body temperature sensing.

[0006] To achieve the above objectives, this application provides the following technical solution: A three-layer covered yarn consists of an inner layer, a middle layer, and an outer layer; wherein the inner layer material is composed of hollow fibers, the middle layer material is composed of conductive fibers, and the outer layer material is composed of irregularly shaped cross-section fibers.

[0007] In some specific implementations, the hollow fiber is a synthetic fiber with a hollow structure; the synthetic fiber is preferably polyester or nylon.

[0008] In some specific implementations, the hollow fiber has a hollowness ratio of 20-50%, preferably 30-40%.

[0009] In some specific implementations, the linear density of the inner layer material is 50-300D, preferably 75-150D.

[0010] In some specific implementations, the number of monofilaments in the inner layer material is 24-288F, preferably 48-96F.

[0011] In some specific implementations, the inner layer material has a specification of 75D / 48F.

[0012] In some specific implementations, the inner layer material accounts for 20-50% of the total weight of the three-layer covering yarn, preferably 30-40%.

[0013] In some specific implementations, the conductive fiber is a synthetic fiber with a surface coated with a conductive component; the synthetic fiber is preferably polyester or nylon.

[0014] In some specific implementations, the conductive component is a mixture of NTC thermistor material and conductive silver paste.

[0015] In some specific implementations, the NTC thermistor material is a manganese-nickel-cobalt composite metal oxide (Mn-Ni-Co-O).

[0016] In some specific implementations, the NTC thermistor material is Mn. (3-x-y) Ni x Co y O4, where 0.1≤x≤1.5, 0≤y≤1.2, and 0.2≤x+y≤2.0, preferably 0.4≤x+y≤0.8.

[0017] In some specific implementations, the B value of the NTC thermistor material at 25 / 50°C is 3700K to 4600K.

[0018] In some specific implementations, the NTC thermistor material is Mn. 2.4 Ni 0.3 Co 0.3 O4, Mn 2.2 Ni 0.4 Co 0.4 O4 or Mn2Ni 0.5 Co 0.5 O4.

[0019] In some specific implementations, the weight ratio of the NTC thermistor material to the conductive silver paste is 1:2 to 2:1.

[0020] In some specific implementations, the conductive component accounts for 10-30% of the total weight of the intermediate layer material.

[0021] In some specific implementations, the linear density of the intermediate layer material is 20-100D, preferably 30-50D.

[0022] In some specific implementations, the number of monofilaments in the intermediate layer material is 24-288F, preferably 24-48F.

[0023] In some specific implementations, the intermediate layer material has a specification of 30D / 24F.

[0024] In some specific implementations, the intermediate layer material accounts for 10-40% of the total weight of the three-layer covering yarn, preferably 20-30%.

[0025] In some specific implementations, the irregularly shaped cross-section fiber is a synthetic fiber with an irregular cross-section; the synthetic fiber is preferably polyester or nylon.

[0026] In some specific implementations, the irregular cross-section is selected from any one of the following: elliptical, trilobal, tetralobal, triangular, quadrilateral, star-shaped, Y-shaped, cross-shaped, and groove-shaped cross-sections, preferably a cross-shaped or Y-shaped cross-section.

[0027] In some specific implementations, the linear density of the outer layer material is 20-150D, preferably 50-100D.

[0028] In some specific implementations, the number of monofilaments in the outer layer material is 24-288F, preferably 36-72F.

[0029] In some specific implementations, the outer layer material has a specification of 50D / 36F.

[0030] In some specific implementations, the outer layer material accounts for 20-50% of the total weight of the three-layer covering yarn, preferably 30-40%.

[0031] In some specific implementations, the intermediate layer material has opposite twist directions to the outer layer material.

[0032] One embodiment of this application is as follows: Any of the aforementioned methods for preparing the three-layer covered yarn is selected from any of the following: Scenario 1, the method for preparing the three-layer covered yarn includes the following steps: S1. The inner layer material is covered with the middle layer material to obtain the first yarn; S2. The outer layer material is used to cover the first yarn to obtain the second yarn; S3. Heat the second yarn to obtain the three-layer covered yarn; Scenario 2, the method for preparing the three-layer covered yarn includes the following steps: S1. The inner layer material is covered with the middle layer material to obtain the first yarn; S2. Heat the first yarn to obtain the third yarn; S3. The outer layer material is used to cover the third yarn to obtain the three-layer covered yarn; In any of the aforementioned cases, the twist direction of the intermediate layer material is opposite to that of the outer layer material.

[0033] In some specific implementations, the twist of the intermediate layer material is 200-1000 twists / meter, preferably 500-600 twists / meter.

[0034] In some specific implementations, the twist of the outer layer material is 200-1000 twists / meter, preferably 300-400 twists / meter.

[0035] In some specific implementations, the twist direction of the intermediate layer material is Z-twist, and the twist direction of the outer layer material is S-twist.

[0036] In some specific implementations, the twist direction of the intermediate layer material is S-twist, and the twist direction of the outer layer material is Z-twist.

[0037] In some specific implementations, the inner layer material is not self-twisted, or is self-twisted before or during coating; the twist of the self-twisting is not higher than 100 twists / meter, and preferably is not self-twisted.

[0038] In some specific implementations, the intermediate layer material is not self-twisted, or is self-twisted before or during coating; the twist of the self-twisting is not higher than 100 twists / meter, and preferably is not self-twisted.

[0039] In some specific implementations, the outer layer material is not self-twisted, or is self-twisted before or during coating; the twist of the self-twisting is no higher than 100 twists / meter, and preferably it is not self-twisted.

[0040] In some specific implementations, the heat treatment is carried out in a biphenyl heating pipe.

[0041] In some specific implementations, the biphenyl heating pipe has an operating length of 2-3 meters.

[0042] In some specific implementations, the heat treatment is carried out at 160-190°C.

[0043] In some specific implementations, the heat treatment is carried out at 170-180°C.

[0044] In some specific implementations, the heating treatment lasts for 3-15 seconds, preferably 5-8 seconds.

[0045] In some specific implementation schemes, the outer layer material undergoes hydrophilic treatment before use.

[0046] In some specific implementations, the hydrophilic finishing is performed using a polyether-modified polysiloxane hydrophilic finishing agent, applied by impregnation.

[0047] In some specific implementations, the intermediate layer material undergoes tension balancing treatment before use.

[0048] In some specific implementations, the tension balancing process is performed on the guide roller, which rotates at a speed of 300-500 meters per minute, and the tension is controlled at 0.1-0.3 cN / dtex.

[0049] The technical solution provided in this application has the following beneficial effects: (1) The three-layer covered yarn provided in this application has an optimized sandwich-like layered functional structure, which effectively avoids conflicts between functions while achieving synergistic enhancement of functions. In the three-layer structure, the inner layer is made of hollow fiber material, which not only provides heat preservation but also quickly conducts heat from the skin to the middle layer and facilitates the expulsion of hot and humid gases and sweat. The middle layer is made of conductive fiber material, which constitutes the core body temperature sensing element and the main conductive path. The outer layer is made of irregular cross-section fiber material, whose unique cross-section structure gives a significant capillary effect, which can quickly guide the sweat and hot and humid gases discharged from the inner layer to the fabric surface and accelerate evaporation, thereby significantly improving wearing comfort. At the same time, the outer layer material plays a physical isolation and protection role for the middle layer, effectively reducing friction and wear and performance degradation of the middle layer during wear, and improving the overall durability and long-term functional stability of the yarn.

[0050] (2) The middle layer of the three-layer covering yarn provided in this application can be a composite coating of negative temperature coefficient (NTC) thermistor material and conductive silver paste. Its resistance value changes with temperature and exhibits high sensitivity and linear response characteristics, thereby enabling faster and more accurate body temperature monitoring.

[0051] (3) The preparation method provided in this application can form a mechanically mutually restrictive double helix structure by coating the middle layer and the outer layer materials with opposite twist directions. This can not only effectively offset the residual torque introduced during twisting and avoid yarn self-rotation and structural loosening, but also generate significant radial compression and strain locking effects during yarn stretching, thereby inhibiting relative slippage between fibers, improving overall structural stability, and helping to maintain the continuity of conductive path and the stability of electrothermal performance under large strain conditions.

[0052] (4) The preparation method provided in this application can be achieved using a coating machine with an integrated online heat treatment device, completing the structural forming and functional activation steps on the same equipment. The dynamic thermal management process provided in this application significantly simplifies the preparation process of the three-layer coated yarn, achieving efficient bonding of each functional layer. The preparation method can utilize the short-time high-temperature treatment of the biphenyl heating pipe to cause the conductive coating of the middle layer to melt and level and firmly bond with the inner layer, while maintaining the integrity of the physical properties of each fiber layer, thereby forming a stable and continuous functional network.

[0053] (5) The three-layer covered yarn provided in this application has multiple functions such as high-efficiency conductivity, active moisture absorption and perspiration and high-precision body temperature sensing, which provides a high-performance core material basis for smart wearable textiles and has good market application prospects. Invention Details Terminology Explanation All patents and other publications cited herein are incorporated herein in their entirety. In the event of any conflict between any description of terminology herein and any document incorporated herein by reference, this document shall prevail.

[0054] Numerical ranges can be represented by a hyphen "-" or a tilde "~". Unless otherwise stated, the range should be understood to encompass both the endpoint values ​​and any values ​​in between. There are no particular restrictions on the type of numeric values ​​within the range, including but not limited to integers, decimals, fractions, percentages, etc., unless explicitly excluded by the context or a particular numeric type is technically unavailable. The type of numeric values ​​within the range is not limited by the specific representation of the endpoints.

[0055] The terms “including,” “containing,” and similar expressions have a non-restrictive meaning.

[0056] "Optional" is used to indicate that a certain feature (including but not limited to components, steps, parameters or structures) may be present in some embodiments, but may not appear in other embodiments, thereby providing technical flexibility for different implementations without departing from the core concept of the present invention.

[0057] A “combination” of the enumeration items refers to any two or more of the enumeration items that coexist or are used together, including but not limited to any two-item combination, any three-item combination, any more items, and any combination of all the enumeration items, unless the context explicitly excludes it or a particular combination is technically impossible.

[0058] The use of ordinal terms such as “first” and “second” to distinguish elements with the same name (e.g., first yarn, second yarn) does not necessarily indicate that any element has any priority, order, or hierarchy relative to another required element, but is merely used as a marker.

[0059] The use of labels such as a), b), i), ii), 1), 2), S1, S2, etc. to number the steps of a method is only for the convenience of description and reading, and does not mean that the corresponding steps must be performed in the order of the numbers, unless the text explicitly states or the information in the text can be clearly inferred that there is a logical or temporal relationship between specific steps.

[0060] When the content or amount of each raw material or component is provided in the form of "%", unless otherwise specified, it is assumed to be a mass percentage (wt%).

[0061] "Fiber" refers to long, spinnable materials used in yarns, fabrics, and related textiles, including but not limited to natural fibers, regenerated fibers, and synthetic fibers. Exemplary natural fibers include cotton, wool, and silk. Exemplary regenerated fibers include viscose, lyocell, and acetate fibers. "Synthetic fiber" refers to fibers whose main component is one or more artificially synthesized polymers. Exemplary synthetic fibers include polyester, polyamide, polyurethane, polyolefin, polyacrylonitrile, and polyaramid fibers. Fiber materials may consist of one or more monofilaments of one or more different types. The specifications of fiber materials are typically expressed as a combination of "linear density / number of monofilaments." "Linear density" refers to the mass of a unit length of fiber material, measured in denier (D), defined as the mass (in grams) of 9000 meters of fiber material. For example, 9000 meters of 75D fiber material has a mass of approximately 75 grams. "Number of monofilaments" refers to the number of monofilaments in the fiber material, typically indicated by "F." For example, 36F fiber material consists of 36 monofilaments.

[0062] "Polyester fiber" refers to a synthetic fiber with one or more polyesters as the main component, optionally also containing one or more other polymers and / or functional auxiliaries and / or common impurities (e.g., residues of reactants or reagents). The polyester content in the polyester fiber exceeds 50% (mass fraction), preferably not less than 85%. Exemplary polyesters include polyethylene terephthalate (PET), polypropylene terephthalate (PTT), polybutylene terephthalate (PBT), polycyclohexanedimethyl terephthalate (PCT), polylactic acid (PLA), etc. Polyester fibers can be blended with other types of fibers. In this application, "polyester" refers to a fiber material composed of 85%-100% polyester fibers (especially PET fibers) and 0-15% other types of fibers.

[0063] "Polyamide fiber" refers to a synthetic fiber with one or more polyamides as the main component, and optionally also containing one or more other polymers and / or functional auxiliaries and / or common impurities (e.g., residues of reactants or reagents). The polyamide content in the polyamide fiber is more than 50% (mass fraction), preferably not less than 85%. Polyamides (PAs) can be obtained through three methods: Method 1, by polycondensation of diamines (such as ethylenediamine, butanediamine, pentanediamine, hexamethylenediamine, decanediamine, trimethylhexanediamine, isophoronediamine, m-phenylenediamine, terephthalic acid, etc.) with diacids (such as oxalic acid, succinic acid, adipic acid, sebacic acid, dodecanoic acid, terephthalic acid, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, etc.); Method 2, by ring-opening polymerization of lactams (such as caprolactam, laurolactam, etc.); Method 3, by polycondensation of amino acids (such as 6-aminohexanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, etc.). Polyamides obtained through Method 1 can be represented by "PAxy", where x and y represent the number of carbon atoms in the diamine and diacid residues, respectively. Polyamides obtained through Method 2 or 3 can be represented by "PAx", where x represents the number of carbon atoms in the lactam or amino acid residue. Exemplary polyamides include polycaprolactam (PA6), polyhexamethylene adipamide (PA66), polyundecanoamide (PA11), and polydodecanoamide (PA12). Polyamide fibers can be blended with other types of fibers. In this application, "nylon" refers to a fiber material composed of 85%-100% polyamide fibers and 0-15% other types of fibers.

[0064] Hollow fiber refers to fibrous materials with interconnected cavities within their cross-section. The volume fraction of hollow fiber can be expressed as the "hollow ratio," which can be controlled through the spinning process and is generally designed to be approximately 20-70%. A higher hollow ratio means more stagnant air per unit length of fiber. Stagnant air has extremely low thermal conductivity, resulting in better heat insulation. High thermal conductivity fiber materials (such as polyester and nylon) can also be made into hollow structures, enabling them to retain heat while allowing for rapid longitudinal heat conduction.

[0065] "Conductive fiber" refers to fiber materials with conductive properties. Their conductivity typically originates from the conductive pathways formed by conductive components (such as metals, carbon materials, and conductive polymers) in the fiber matrix or surface modifications. Conductive fibers include, but are not limited to, metal fibers, carbon-based conductive fibers, conductive polymer fibers, and modified fibers that acquire conductivity through techniques such as plating, coating, and doping. They can be used to achieve functions such as static dissipation, electromagnetic shielding, electrothermal conversion, signal transmission, and sensing.

[0066] A negative temperature coefficient (NTC) thermistor is a resistive material whose resistance decreases significantly with increasing temperature. NTC thermistor materials are typically composed of two or more transition metal oxides (such as oxides of manganese, nickel, cobalt, and iron), exhibiting a predictable resistance-temperature response relationship during temperature changes. This allows them to be used for temperature measurement, control, compensation, and surge current suppression. The B-value (also known as the B constant) of an NTC thermistor material characterizes its sensitivity to temperature changes. It is usually calculated by measuring the resistance at two different temperature points (e.g., 25°C and 50°C) and applying an exponential function. Generally, all other things being equal, a larger B-value indicates greater sensitivity to temperature changes, and a steeper resistance-temperature characteristic.

[0067] "Conductive silver paste" refers to a silver-based conductive paste in a coatable / printable state, in which silver powder (including silver microparticles, silver nanoparticles, or silver flakes, etc.) is dispersed and suspended in a carrier system as the main conductive functional phase. Conductive silver paste usually also includes components such as binders, additives, and solvents, which enable the silver powder to be evenly distributed on the fiber surface and form a conductive coating after drying or curing.

[0068] "Irregular cross-section fiber" refers to fiber materials with irregular cross-sections (i.e., non-circular cross-sections). These irregular cross-sections include, but are not limited to, elliptical, multi-lobed (e.g., trilobal, tetralobal), polygonal (e.g., triangular, quadrilateral, star-shaped), Y-shaped, cross-shaped, and grooved shapes. These shapes enable the fiber to possess unique properties different from traditional circular cross-section fibers, such as special luster, higher specific surface area, excellent moisture-wicking ability, improved fluffiness and feel, and different mechanical properties.

[0069] "Twist" refers to the process of rotating fibers or filaments along a longitudinal axis to form a helical arrangement. "Twist direction" is usually marked as "S-twist" or "Z-twist," indicating that the direction of the fiber or filament relative to the longitudinal axis is aligned with the diagonal direction of the letter "S" or "Z," respectively. "Twist degree" indicates the number of spiral turns per unit length.

[0070] "Hydrophilic finishing" refers to the hydrophilic modification treatment of the surface of fibers, yarns, or fabrics through physical or chemical methods. Hydrophilic finishing can use hydrophilic compounds as finishing agents, forming a hydrophilic film on the surface of fibers, yarns, or fabrics through methods such as impregnation, coating, or spraying. Exemplary hydrophilic finishing agents include, but are not limited to, hydrophilic polysiloxanes, polyether-modified polymers, and acrylic hydrophilic resins. Hydrophilic finishing can also employ physical surface activation treatments, such as oxidizing or introducing hydrophilic groups onto the surface of fibers, yarns, or fabrics through plasma radiation, ozone, or ultraviolet light. Hydrophilic finishing can also employ coating curing methods, such as applying a hydrophilic coating material to the surface of fibers, yarns, or fabrics and then curing it to obtain a hydrophilic functional layer. Hydrophilic finishing can also be achieved by grafting hydrophilic groups or polymers onto the surface of fibers, yarns, or fabrics. Fibers, yarns, or fabrics treated with hydrophilic finishing typically have a lower water contact angle and a higher moisture absorption rate, which is beneficial for sweat management and wearing comfort.

[0071] "Tension balancing treatment" refers to a pretreatment process that applies controllable tension adjustment to fibrous materials, causing their internal residual stress and initial tension distribution to tend towards uniformity and stability. Tension balancing treatment typically utilizes tension control devices, fixed-length relaxation devices, or tension-sensor-based feedback adjustment systems to apply appropriate tensile tension to the material and then relax it to a preset tension level under controlled conditions. Tension balancing treatment helps reduce problems such as deformation, twisting, and strength fluctuations caused by uneven tension during subsequent processing.

[0072] "Smart wearable textiles" refer to textile materials and products capable of sensing, responding to, or interacting with the environment or human body status during wear. Smart wearable textiles typically include fibers, yarns, fabrics, and finished garments. They can integrate functions to collect information (e.g., temperature, motion, physiological signals) and transmit, process, or provide feedback on this information to support intelligent functions (e.g., intelligent sensing, status monitoring, or environmental response). The functional forms of smart wearable textiles can be passive (sensing only), active (sensing and responding), or interactive (including data transmission and processing functions), and they can be applied to scenarios such as health monitoring, motion feedback, and environmental adaptation. Specific Implementation The raw materials used in this application can be purchased or synthesized in-house. The following specific embodiments are used to further describe the implementation of the present invention and do not limit the scope of the invention.

[0074] Example 1 The inner layer material is a high thermal conductivity polyester filament with a hollow rate of 20% (75D / 48F, PET content ≥98%), which accounts for 40% of the weight of the three-layer covering yarn. The middle layer material is a nylon filament (30D / 24F, PA6 content ≥98%) coated with a mixture of NTC thermosensitive material (Mn-Ni-Co-O series) and conductive silver paste (weight ratio 1.5:1, coating accounts for 30% of the total weight of the middle layer material), which accounts for 30% of the weight of the three-layer covering yarn. The outer layer material is a Y-shaped nylon moisture-wicking fiber (50D / 36F), which accounts for 30% of the weight of the three-layer covering yarn.

[0075] The intermediate and outer layer materials are pretreated separately. The outer layer's irregularly shaped cross-section fibers are treated with a polyether-modified polysiloxane hydrophilic finishing agent via impregnation to enhance surface hydrophilicity and moisture wicking rate. The intermediate layer sensing yarn undergoes tension balancing treatment, with the guide roller speed controlled at 300-500 m / min and the tension stabilized at 0.1-0.3 cN / dtex. The inner, intermediate, and outer layer materials are then fed into a hollow spindle twisting machine, with the intermediate layer twist set at 550 twists / m (Z-twist) and the outer layer twist at 350 twists / m (S-twist) for wrapping. The opposite twist directions counteract residual yarn torque, increasing structural compactness and forming a stable helical winding reverse-wrapping structure. The formed yarn immediately enters the biphenyl heating pipe and is treated at 175°C for 5 seconds to allow the conductive coating in the middle layer to fully melt and flow and tightly bond with the inner fiber, thus completing the functional activation and structural shaping. Finally, a mechanically stable and functionally synergistic three-layer covered yarn is obtained and wound into a bobbin under constant tension.

[0076] Example 2 Following the preparation method of Example 1, the inner layer material is a high thermal conductivity nylon filament (75D / 48F, PA6 content ≥98%) with a hollow ratio of 30%, accounting for 35% of the total yarn weight; the middle layer material is a polyester filament (30D / 24F, PET content ≥98%) coated with a mixture of NTC thermistor (Mn-Ni-Co-O) and conductive silver paste (weight ratio 1.5:1, coating accounts for 20% of the total weight of the middle layer material), accounting for 25% of the total yarn weight; the outer layer material is a Y-shaped cross-section nylon filament (50D / 36F), accounting for 40% of the total yarn weight. The twist of the middle layer is 550 twists / meter (Z twist), and the twist of the outer layer is 350 twists / meter (S twist). Bisphenyl heating is performed at 180°C for 6 seconds. The remaining conditions and steps are the same as in Example 1, resulting in a three-layer covered yarn.

[0077] Example 3 Following the preparation method of Example 1, the inner layer material is a high thermal conductivity hollow polyester filament (100D / 72F, PET≥98%) with a hollow rate of 35%, accounting for 35% of the total weight of the three-layer covered yarn; the middle layer material is a nylon filament (40D / 36F, PA6 content≥98%) coated with a mixture of NTC thermistor material (Mn-Ni-Co-O series) and conductive silver paste (weight ratio 1:2, coating accounts for 20% of the total weight of the middle layer material), accounting for 25% of the total weight of the three-layer covered yarn; the outer layer material is a cross-shaped nylon fiber (60D / 48F), accounting for 40% of the total weight of the three-layer covered yarn. The twist of the middle layer is 550 twists / meter (Z twist), and the twist of the outer layer is 350 twists / meter (S twist). Biphenyl heating is performed at 170°C for 7 seconds. The remaining conditions and steps are the same as in Example 1, resulting in the three-layer covered yarn.

[0078] Example 4 Following the preparation method of Example 1, the inner layer material is a high thermal conductivity hollow nylon filament (75D / 48F, PA6≥98%) with a hollow rate of 50%, accounting for 30% of the total weight of the three-layer covered yarn; the middle material is a polyester filament (30D / 24F, PET≥98%) coated with a mixture of NTC thermistor material (Mn-Ni-Co-O series) and conductive silver paste (weight ratio 2:1, coating accounts for 25% of the total weight of the middle layer material), accounting for 30% of the total weight of the three-layer covered yarn; the outer layer material is a Y-shaped cross-section polyester moisture-wicking fiber (50D / 36F), accounting for 40% of the total weight of the three-layer covered yarn. The twist of the middle layer is 580 twists / meter (S twist), and the twist of the outer layer is 380 twists / meter (Z twist). Biphenyl heating is performed at 180°C for 5 seconds. The remaining conditions and steps are the same as in Example 1, resulting in the three-layer covered yarn.

[0079] Comparative Example 1 Referring to the preparation method of Example 1, the inner layer material was replaced with ordinary solid polyester filament (75D / 48F) of the same specification and material, while the other conditions and steps remained unchanged, and a three-layer covered yarn without hollow inner layer structure was prepared to compare the effect of hollow structure on heat preservation, moisture absorption and moisture wicking performance.

[0080] Comparative Example 2 Referring to the preparation method of Example 1, the intermediate conductive coating was adjusted, the NTC thermistor material component was removed, and only the surface of the nylon filament (30D / 24F) was coated with a pure conductive silver paste coating. The coating mass ratio was kept the same as in Example 1, and the other conditions and steps remained unchanged. A three-layer covered yarn without body temperature sensing function was prepared to compare the effect of NTC thermistor material on temperature sensing accuracy and response characteristics.

[0081] Comparative Example 3 Referring to the preparation method of Example 1, the twist direction of the middle layer and the outer layer is uniformly set as Z twist, the twist of the middle layer and the outer layer is consistent with that of Example 1, and the other conditions and steps remain unchanged, so as to obtain a three-layer covered yarn with the same twist direction, which is used to compare the effect of the reverse twist structure on the yarn mechanical stability, resistance retention rate and durability.

[0082] Example 5 In this embodiment, the performance of the three-layer covered yarn prepared in the aforementioned embodiments and comparative examples is tested using the following methods.

[0083] Conductivity: According to GB / T 14342-2015 "Test Method for Specific Resistivity of Short Chemical Fibers", the volume resistivity of the yarn is tested to characterize the continuity of the conductive path.

[0084] Body temperature sensing performance: Using a self-made constant temperature measurement and control platform, the resistance-temperature linear correlation coefficient and response time were tested within the human body temperature range of 30-40℃ to characterize the temperature sensing accuracy.

[0085] Moisture wicking performance: According to GB / T 21655.1-2008 "Evaluation of moisture absorption and quick-drying properties of textiles - Part 1: Single combination test method", the drip diffusion time and vertical wicking height are tested to characterize the moisture wicking rate.

[0086] Structural stability: According to GB / T 3923.1-2013 "Textiles - Tensile properties of fabrics - Part 1: Determination of breaking strength and elongation at break", the resistance change rate under 10% constant elongation was tested to characterize the functional stability under large strain.

[0087] Thermal insulation performance: According to GB / T 11048-2018 "Determination of thermal resistance and moisture resistance of textiles under steady-state conditions for physiological comfort", the Clo value is tested to characterize the thermal insulation ability.

[0088] Table 1. Performance test results of three-layer covered yarn

[0089] The three-layer covered yarn disclosed in this application achieves a synergistic integration of efficient conductivity, high-precision body temperature sensing, active moisture absorption and wicking, and good heat retention through a three-layer structure design consisting of an inner hollow fiber layer, a middle NTC conductive sensing fiber, and an outer irregular cross-section moisture-wicking fiber. The middle and outer layers are covered with opposite twist directions, combined with online biphenyl dynamic heat treatment, which makes the yarn structure stable, the interlayer bonding strong, and it resistant to tension and wear. This solves the technical problems of traditional smart yarns, such as the mutual restriction between conductivity and moisture absorption, low sensing accuracy, easy loosening of structure, and easy functional decay.

[0090] This application has described the basic concepts. Obviously, for those skilled in the art, the above detailed disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0091] Meanwhile, this application uses specific terms to describe its embodiments. For example, "an embodiment," "one embodiment," "some embodiments," and / or "some implementations" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this application do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0092] It should be noted that the above embodiments are only used to illustrate the principles and effects of the present invention, and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make various adjustments and changes to the material ratios and process parameters (such as rotational speed, temperature, and length-to-diameter ratio) in the above embodiments without departing from the concept and scope of the present invention. Such adjustments and changes all fall within the scope of protection of the present invention.

[0093] Similarly, it should be noted that, in order to simplify the description of this application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of this application sometimes combines multiple features into one embodiment or description thereof. However, this disclosure method does not imply that the subject matter of this application requires more features than those mentioned in the claims.

[0094] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other modifications may also fall within the scope of this application. Therefore, alternative configurations of the embodiments of this application are considered as examples and not limitations, and are regarded as consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly described and illustrated in this application.

Claims

1. A three-layer covered yarn consisting of an inner layer, an intermediate layer and an outer layer; wherein, The inner layer material is composed of hollow fibers with a hollowness ratio of 20-50%; the middle layer material is composed of conductive fibers, which are fibers coated with a conductive component; the conductive component is a mixture of NTC thermistor material and conductive silver paste; the outer layer material is irregularly shaped cross-section fiber.

2. The three-layer cover yarn according to claim 1, characterized in that The linear density of the inner layer material is 50-300D, preferably 75-150D; The number of monofilaments in the inner layer material is 24-288F, preferably 48-96F; Preferably, the inner layer material has a specification of 75D / 48F.

3. The three-layer cover yarn of claim 1, wherein The inner layer material accounts for 20-50% of the total weight of the three-layer covered yarn, preferably 30-40%.

4. The three-layer cover yarn of claim 1, wherein The linear density of the intermediate layer material is 20-100D, preferably 30-50D; The number of monofilaments in the intermediate layer material is 24-288F, preferably 24-48F; Preferably, the intermediate layer material has a specification of 30D / 24F.

5. The three-layer cover yarn of claim 1, wherein The intermediate layer material accounts for 10-40% of the total weight of the three-layer covered yarn, preferably 20-30%; Preferably, the mixture of the NTC thermistor material and the conductive silver paste accounts for 10-30% of the total weight of the intermediate layer material; Preferably, the weight ratio of the NTC thermistor material to the conductive silver paste is 1:2 to 2:

1.

6. The three-layer cover yarn of claim 1, wherein The irregular cross-section fiber is a synthetic fiber with an irregular cross-section, and the synthetic fiber is preferably polyester or nylon; Preferably, the irregular cross-section is selected from any one of the following: elliptical, trilobal, tetralobal, triangular, quadrilateral, star-shaped, Y-shaped, cross-shaped, and groove-shaped cross-sections.

7. The three-layer cover yarn of claim 1, wherein The linear density of the outer layer material is 20-150D, preferably 50-100D; The number of monofilaments in the outer layer material is 24-288F, preferably 36-72F; Preferably, the outer layer material has a specification of 50D / 36F.

8. The three-layer cover yarn of claim 1, wherein The outer layer material accounts for 20-50% of the total weight of the three-layer covering yarn, preferably 30-40%.

9. A process for the production of the three-layer covering yarn according to claim 1, characterized in that, Includes steps in any of the following scenarios: Scenario 1, S1: The inner layer material is covered with an intermediate layer material to obtain the first yarn; S2. The first yarn is covered with an outer layer material to obtain a second yarn; S3. Heat the second yarn to obtain the three-layer covered yarn; Scenario 2, S1: The inner layer material is covered with an intermediate layer material to obtain the first yarn; S2. Heat the first yarn to obtain the third yarn; S3. The third yarn is covered with an outer layer material to obtain the three-layer covered yarn.

10. The three-layer cover yarn according to claim 9, characterized in that The twist of the intermediate layer material and the outer layer material are each independently 200-1000 twists / meter, and their twist directions are opposite. Preferably, the twist of the intermediate layer material is 500-600 twists / meter; Preferably, the twist of the outer layer material is 300-400 twists / meter.

11. The three-layer cover yarn of claim 9, wherein The heat treatment is carried out in a biphenyl heating pipe; The heat treatment is preferably carried out at 160-190°C; The heating treatment time is preferably 3-15 seconds, more preferably 5-8 seconds.

Images