Ecological texture comfortable multifunctional elastic composite yarn and manufacturing method thereof

Abstract

The invention provides an ecological texture comfortable type multifunctional elastic composite yarn and a manufacturing method thereof, the ecological texture comfortable type multifunctional elastic composite yarn comprises a core layer, the core layer is an elastic core yarn formed by blending low-viscosity PET and high-shrinkage PET according to the mass ratio of (5-7): (3-5), the intrinsic viscosity of the low-viscosity PET at 25 DEG C is 0.47-0.65 dL / g, and the boiling water shrinkage rate of the high-shrinkage PET is larger than or equal to 20%; the outer side of the core layer is coated with the middle layer, and the middle layer is formed by blending modified bio-based polytrimethylene terephthalate fibers and regenerated polyester fibers according to the mass ratio of (3-5): (5-7); the outer layer wraps the outer side of the middle layer, and the outer layer is formed by blending modified China hemp fibers and lyocell fibers according to the mass ratio of (2-4): (6-8); the synergistic improvement of spandex replacement, ecological environmental protection, comfortable texture and multi-function integration is achieved, meanwhile, the production process is optimized, and energy consumption and pollutant emission are reduced.

Description

Technical Field

[0001] This invention relates to the field of composite yarn technology, and in particular to an eco-friendly, comfortable, multifunctional elastic composite yarn and its manufacturing method. Background Technology

[0002] As the global textile industry transforms and upgrades towards green, functional, and high-end directions, consumer demand for textiles has expanded from simple basic performance characteristics to diversified directions such as eco-friendliness, comfort, and multi-functional integration. Especially in the fields of high-end knitwear, home textiles, and functional clothing, composite yarns that combine elasticity, comfort, eco-friendliness, and multi-functionality have become a research hotspot.

[0003] Currently, most mainstream elastic composite yarns on the market use spandex as the elastic core, which is then combined with other fibers through wrapping or twisting processes. However, this type of yarn suffers from the following common technical bottlenecks: 1. Environmental and performance defects caused by dependence on spandex. The production process of spandex involves a large amount of organic solvents, resulting in poor environmental performance. Furthermore, spandex is prone to aging during use, has poor resistance to chlorine bleaching, and insufficient resilience, leading to fabrics that easily loosen and deform after long-term use. For example, after 50 stretching cycles, the elastic recovery rate of conventional spandex-covered yarn typically decreases by more than 15%, making it difficult to meet the requirements of high-end textiles for durable elasticity.

[0004] 2. Limited functionality, making it difficult to balance comfort and versatility. Existing composite yarns often focus on developing a single function, such as achieving antibacterial properties solely through the addition of antibacterial agents, or achieving elasticity solely through spandex. However, they lack multi-layered structural synergistic design, making it difficult to simultaneously achieve multiple properties such as elasticity, antibacterial properties, UV protection, and skin-friendly breathability. For example, while single hemp fiber has antibacterial properties, it has a rough feel; while single lyocell fiber is soft, it lacks mechanical strength and has no antibacterial function. How to integrate multiple functions without sacrificing comfort and texture remains an industry challenge.

[0005] 3. The production process is not green, and energy consumption and pollution problems are prominent. Traditional elastic composite yarn production processes often employ ring spinning + high-temperature, high-pressure dyeing + oil-based crosslinking finishing, which presents the following problems: The dyeing process is energy-intensive (dyeing temperature ≥130℃) and produces a large amount of COD in wastewater. Oil-based crosslinking finishing agents easily release harmful substances such as formaldehyde, which does not conform to the concept of green environmental protection. The production process makes it difficult to achieve efficient utilization of bio-based and regenerated fibers.

[0006] To address the aforementioned issues, existing technologies have disclosed some improvement solutions. For example, a "bio-based elastic composite yarn" has been disclosed, which uses bio-based polyester fiber combined with spandex. While this improves environmental friendliness to some extent, it still has the following drawbacks: It still relies on spandex to provide elasticity, and has not fundamentally solved the problems of spandex's environmental friendliness and resilience stability; The double-layer structure lacks an intermediate transition layer, resulting in insufficient bonding between the core layer and the outer layer, and poor structural stability. It has limited functionality, achieving only limited environmental friendliness through the inherent properties of bio-based polyester fibers, without integrating multiple functions such as antibacterial, anti-UV, and pearlescent effects. The finishing process still uses the traditional high-temperature and high-pressure dyeing process, and COD emissions are not significantly reduced. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide an eco-friendly, comfortable, multifunctional elastic composite yarn and its manufacturing method. This invention solves the technical problems of insufficient environmental friendliness, imbalance between elasticity and texture, limited functionality, and non-green production processes in existing elastic composite yarns. It achieves a synergistic improvement in elasticity, structural stability, eco-friendly texture, and multifunctionality, while optimizing the production process and reducing energy consumption and pollutant emissions.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides an eco-friendly, comfortable, multifunctional elastic composite yarn, comprising: The core layer is an elastic core yarn formed by blending low-viscosity PET and high-shrinkage PET in a mass ratio of (5-7):(3-5), wherein the intrinsic viscosity of the low-viscosity PET at 25°C is 0.47-0.65 dL / g, and the boiling water shrinkage rate of the high-shrinkage PET is ≥20%. The middle layer covers the outside of the core layer and is formed by blending modified bio-based poly(propylene terephthalate) fiber and recycled polyester fiber in a mass ratio of (3-5):(5-7). The outer layer covers the outside of the middle layer and is formed by blending modified hemp fiber and lyocell fiber in a mass ratio of (2-4):(6-8).

[0009] This invention provides an eco-friendly, comfortable, multifunctional elastic composite yarn and its manufacturing method, which solves the technical problems of insufficient environmental protection, imbalance between elasticity and texture, single functionality, and non-green production process in the prior art. It achieves a synergistic improvement in elasticity, structural stability, eco-friendly texture, and multifunctionality, while optimizing the production process and reducing energy consumption and pollutant emissions.

[0010] In some embodiments, the modified bio-based polypropylene terephthalate fiber is modified with maleic anhydride grafting.

[0011] In some embodiments, the outer layer is provided with 0.8 to 1.2 wt% pearlescent pigment and 0.3 to 0.7 wt% antistatic agent, wherein the pearlescent pigment has a particle size of 1 to 3 μm.

[0012] In some embodiments, the linear density of the core layer is 8.5~12.5 dtex; The linear density of the middle layer is 15.5~19.5 dtex, its coverage rate is ≥95%, and its coverage twist is 350~390 twists / meter; The linear density of the outer layer is 22.5~26.5 dtex, and its wrapping twist is 400~440 twists / meter.

[0013] In some embodiments, the bus density of the composite yarn is 46.5 to 58.5 dtex.

[0014] On the other hand, the present invention provides a method for manufacturing an eco-friendly, comfortable, multifunctional elastic composite yarn, which, in order to obtain the eco-friendly, comfortable, multifunctional elastic composite yarn as described in any of the preceding claims, includes the following steps: S1 Raw Material Pretreatment: Low-viscosity PET, high-shrinkage PET, modified bio-based poly(propylene terephthalate) fiber, recycled polyester fiber, modified hemp fiber, and lyocell fiber are opened and combed respectively. S2 core layer preparation: Low viscosity PET and high shrinkage PET are spun using vortex spinning process at a spinning speed of 380~420m / min; S3 middle layer coating: Modified bio-based polypropylene terephthalate fiber is blended with recycled polyester fiber and then coated on the outside of the core layer using an airflow coating process. S4 outer layer coating: Modified hemp fiber and lyocell fiber are blended, pearlescent pigments and antistatic agents are added, and after being mixed evenly, they are melt-spun and coated on the outer side of the middle layer.

[0015] In some embodiments, the modified hemp fiber is modified by an alkali treatment process, the modifier is a 5% to 9% sodium hydroxide solution by mass, the modification temperature is 55 to 75°C, and the modification time is 30 to 40 minutes.

[0016] In some implementations, the following steps are also included: S5 finishing: The coated composite yarn is subjected to green cross-linking finishing and natural plant oil setting. The finishing temperature is 80~100℃, the finishing time is 30~50min, the setting temperature is 110~130℃, and the setting time is 20~40min. S6 inspection, winding, and packaging.

[0017] In some embodiments, the green crosslinking finishing uses an environmentally friendly waterborne polyurethane crosslinking agent, which is added at an amount of 2.0 to 3.0 wt% of the composite yarn mass.

[0018] In some embodiments, the natural plant oil agent is a soybean-based natural plant oil agent, and its addition amount is 2.5 to 3.5 wt% of the composite yarn.

[0019] This invention provides an eco-friendly, comfortable, multifunctional elastic composite yarn and its manufacturing method, which has the following beneficial effects: 1) This invention provides an eco-friendly, comfortable, multi-functional elastic composite yarn and its manufacturing method, which solves the technical problems of insufficient environmental protection, imbalance between elasticity and texture, single functionality, and non-green production process in the prior art. It achieves a synergistic improvement in elasticity, structural stability, eco-friendly texture and multi-functionality, while optimizing the production process and reducing energy consumption and pollutant emissions.

[0020] 2) This invention provides an eco-friendly, comfortable, multi-functional elastic composite yarn and its manufacturing method. Through a three-layer composite structure design (core layer, middle layer, and outer layer), this invention achieves a synergistic improvement in elasticity, structural stability, eco-friendliness, and multi-functionality. The core synergistic mechanism is as follows: (1) Core-middle layer synergy: the unity of elastic support and structural stability The core layer is made of two components, low-viscosity PET and high-shrinkage PET, vortex spinning. It utilizes the shrinkage difference of the two components to form a three-dimensional crimped structure, achieving excellent elasticity without the addition of spandex, with an elastic recovery rate of ≥88%, replacing traditional spandex.

[0021] However, the three-dimensional crimped structure of a single core layer is prone to relaxation or deformation during repeated stretching, leading to a decrease in elasticity. The middle layer, formed by a blend of modified bio-based poly(propylene terephthalate) fiber and recycled polyester fiber, creates a tightly wrapped "support layer" on the outside of the core layer. The modified bio-based poly(propylene terephthalate) fiber, due to maleic anhydride grafting modification introducing active groups, significantly enhances its interfacial bonding with the core layer, while the recycled polyester fiber provides excellent mechanical support. This middle layer structure has the following synergistic effects: Limiting excessive deformation of the core layer: The middle layer forms a physical constraint on the three-dimensional curled structure of the core layer, preventing irreversible slippage or relaxation during the stretching and rebound process, thereby controlling the elastic recovery rate attenuation to ≤5% (the attenuation rate is as high as 15% when no middle layer is set in Comparative Example 3). Stress transfer and dispersion: The middle layer acts as a stress transfer medium, uniformly transferring the stress on the outer layer to the core layer, avoiding core layer fracture caused by local stress concentration, and significantly improving the overall breaking strength of the yarn (3.8~4.2 cN / dtex in Examples 1-3, and 3.2 cN / dtex in Comparative Example 1 after the middle layer was removed).

[0022] (2) Middle-outer layer synergy: compatibility of functionality and comfort The outer layer is a blend of modified hemp and lyocell fibers, giving the yarn antibacterial, UV-resistant, skin-friendly, and breathable properties. However, hemp fibers are relatively rigid, and using them alone can easily result in a rough feel; while lyocell fibers are soft, they lack sufficient mechanical strength. The middle layer plays a crucial "buffering and bridging" role here: Optimized feel: The middle layer modified bio-based PTT fiber has natural resilience and softness. Its coating layer effectively alleviates the rigid feel of the outer hemp fiber, so that the yarn can maintain its antibacterial function while also having excellent skin-friendliness (the antibacterial rate dropped to 65.3% after the outer layer was removed in Comparative Example 2, which confirmed that the outer layer is the main carrier of functionality). Functional durability: The middle layer tightly binds the outer fibers together (coverage rate ≥95%), preventing the modified hemp fibers from falling off due to friction during use and ensuring the long-lasting stability of antibacterial and anti-UV functions.

[0023] (3) Outer layer-core layer synergy: balance of texture and elasticity The outer layer is coated with pearlescent pigments, giving the yarn a high-end visual effect; however, the addition of inorganic pigments may affect the yarn's mechanical properties and elasticity. The three-dimensional crimped structure of the core layer plays a "buffering" role here. Elastic buffer: The highly elastic structure of the core layer can absorb the brittle stress caused by the addition of pigments to the outer layer, preventing the yarn from breaking when bent or stretched (the breaking strength of Examples 1-3 is stable above 3.8 cN / dtex). Enhanced texture: The natural breathability of the outer hemp fiber and the crimped structure of the core layer work together to form microporous channels inside the yarn, further improving breathability and moisture-wicking performance, achieving a balance between "texture" and "comfort".

[0024] (4) The overall effect of three-layer synergy The three-layer structure is not a simple functional superposition, but rather a synergistic enhancement loop formed through precise matching of material selection, modification treatment, and process parameters: "elastic support (core layer) - structural stability (middle layer) - functional texture (outer layer)". Elasticity: The core layer provides basic elasticity, while the middle layer ensures the durability of elasticity; Mechanical properties: The middle layer disperses stress, and the outer layer protects the core layer, together improving fracture strength and wear resistance; Multifunctionality: The outer layer provides antibacterial, UV protection, and visual appeal, while the middle layer ensures long-lasting functionality; Eco-friendly: Each layer uses bio-based or recycled fibers, combined with green cross-linking finishing process to achieve environmental protection throughout the entire process. Attached Figure Description

[0025] Figure 1 This invention provides a structural schematic diagram of an eco-friendly, comfortable, multifunctional elastic composite yarn. Among them, 1-Eco-textured comfort multi-functional elastic composite yarn; 11-Outer layer; 12-Middle layer; 13-Core layer. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0027] On the one hand, such as Figure 1 As shown, the present invention provides an eco-friendly and comfortable multi-functional elastic composite yarn with a three-layer structure, consisting of a core layer 13, a middle layer 12, and an outer layer 11 from the inside out. The core layer 13 is made of high-elastic bicomponent yarn by vortex spinning. The high-elastic bicomponent yarn is made of low-viscosity PET and high-shrinkage PET blended in a mass ratio of (5~7):(3~5). The low-viscosity PET has an intrinsic viscosity of 0.47~0.65dL / g as measured by GB / T 14190-2017 at 25℃, and the high-shrinkage PET has a boiling water shrinkage rate ≥20%. The linear density of the core layer is 8.5~12.5dtex. The middle layer 12 is made by blending modified bio-based poly(propylene terephthalate) (PTT) fiber and recycled polyester fiber at a mass ratio of (3~5):(5~7), and then coating it on the outside of the core layer 13 by an air-flow coating process. The linear density of the middle layer 12 is 15.5~19.5 dtex. The modified bio-based PTT fiber is modified by maleic anhydride grafting. The modification principle is to introduce active groups through maleic anhydride grafting to improve the compatibility and bonding force between the fiber and other components, thereby improving the structural stability and mechanical properties of the composite yarn.

[0028] The outer layer 11 is made of modified hemp fiber and lyocell fiber in a mass ratio of (2~4): (6~8) After blending, the outer layer 11 is melt-spun and coated on the outside of the middle layer 12. The linear density of the outer layer 11 is 22.5~26.5 dtex. The modified hemp fiber is modified by alkali treatment. The modifier is a 5%~9% sodium hydroxide solution by mass. The modification temperature is 55~75℃ and the modification time is 30~40min. The modification principle is to remove impurities and lignin from the surface of the hemp fiber by alkali treatment, thereby improving the softness, air permeability and antibacterial properties of the fiber. The outer layer 11 is also added with 0.8~1.2wt% pearlescent pigment and 0.3~0.7wt% antistatic agent. The particle size of the pearlescent pigment is 1~3μm. The pearlescent pigment is a textile-grade mica-based pearlescent pigment. The composition is mica titanium oxide. The temperature resistance is ≥200℃ and the compatibility with textile fibers is ≥90%. The specific model can be the commercially available MC103 pearlescent pigment. The composite yarn has a bus density of 46.5~58.5 dtex, a twist of 380~420 twists / meter, a breaking strength of ≥3.8 cN / dtex, an elastic recovery rate of ≥88%, an elastic recovery rate attenuation of ≤5%, an antibacterial rate of ≥90%, an ultraviolet resistance UPF of ≥30, a formaldehyde residue of ≤0.02 mg / kg, and COD emissions are reduced by more than 80% during the production process.

[0029] After blending low-viscosity PET and high-shrinkage PET, a three-dimensional crimp structure is formed by heat setting, with a crimp degree of 15~20 crimps / 25mm and a crimp elastic recovery rate of ≥90% (the test methods for crimp degree and crimp elastic recovery rate follow GB / T6506-2017 "Test Method for Crimping Performance of Chemical Fibers"). It is this three-dimensional crimp structure that enables the composite yarn to achieve excellent elasticity without spandex, with an elastic recovery rate of ≥88%.

[0030] This invention also discloses a method for manufacturing the above-mentioned eco-friendly, comfortable, multifunctional elastic composite yarn, comprising the following steps: S1 Raw Material Pretreatment: High-elastic bicomponent yarn, modified bio-based polypropylene terephthalate fiber, recycled polyester fiber, modified hemp fiber, and lyocell fiber are opened and combed to remove impurities and ensure uniform dispersion of raw materials; among them, modified bio-based polypropylene terephthalate fiber and modified hemp fiber are prepared in advance according to the above modification process. S2 core layer preparation: High-elastic bicomponent yarn is spun using vortex spinning process, with the vortex spinning linear density controlled at 8.5~12.5dtex and the spinning speed at 380~420m / min to obtain core layer yarn; S3 middle layer coating: Modified bio-based polypropylene terephthalate fiber and recycled polyester fiber are blended at a mass ratio of (3~5):(5~7), and the modified bio-based polypropylene terephthalate fiber is coated on the outside of the core layer using an airflow coating process. The coating rate is ≥95%, the linear density of the middle layer is controlled at 15.5~19.5 dtex, and the coating twist is 350~390 twists / meter. S4 outer layer coating: Modified hemp fiber and lyocell fiber are blended at a mass ratio of (2~4):(6~8), and 0.8~1.2wt% of pearlescent pigment and 0.3~0.7wt% of antistatic agent are added. After mixing evenly, the mixture is melt-spun and coated on the outside of the middle layer. The linear density of the outer layer is controlled at 22.5~26.5dtex, and the coating twist is 400~440 twists / meter. S5 Finishing: The coated composite yarn undergoes green crosslinking finishing and natural plant oil setting. The green crosslinking finishing uses an environmentally friendly water-based polyurethane crosslinking agent, added at 2.0~3.0 wt% of the composite yarn mass, using a padding method (liquor ratio 1:20), a finishing temperature of 80~100℃, and a finishing time of 30~50 min. After crosslinking, the yarn is dried with 25℃ cold air until the moisture content is ≤8%. The natural plant oil setting uses a soybean-based natural plant oil agent, added at 2.5~3.5 wt% of the composite yarn mass, using a spraying method to evenly cover the yarn surface. The setting temperature is 110~130℃, and the setting time is 20~40 min. During setting, the yarn tension is controlled at 4~6 cN. After setting, the yarn is naturally cooled to room temperature. The green crosslinking finishing uses an environmentally friendly crosslinking agent, replacing the traditional high-temperature, high-pressure dyeing process, reducing energy consumption and pollutant emissions. The green crosslinking finishing described in this invention refers to a crosslinking finishing process carried out at a low temperature of 80-100℃, using an environmentally friendly water-based polyurethane crosslinking agent instead of a traditional oil-based crosslinking agent. Compared with traditional high-temperature and high-pressure dyeing and oil-based crosslinking finishing processes, this process has no organic solvent volatilization, reduces energy consumption by more than 50%, and reduces COD emissions from wastewater after the finishing process by more than 80% (measured according to GB / T 11914-1989, see the performance testing section for details), demonstrating significant environmental advantages. S6 Testing, Winding, and Packaging: The performance of the finished composite yarn is tested, including linear density, twist, breaking strength, elastic recovery rate, antibacterial rate, UV protection (UPF), formaldehyde residue, and COD emissions. After passing the tests, the yarn is wound and packaged to obtain the finished product. Example 1

[0031] Example 1 provides an eco-friendly, comfortable, multi-functional elastic composite yarn with a three-layer structure consisting of a core layer, a middle layer, and an outer layer from the inside out: Core layer: made of low viscosity PET (viscosity 0.55dL / g) and high shrinkage PET (boiling water shrinkage rate 22%) blended in a mass ratio of 6:4 by vortex spinning, with a linear density of 10.5dtex and a spinning speed of 400m / min; Middle layer: Modified bio-based poly(propylene terephthalate) fiber and recycled polyester fiber are blended at a mass ratio of 4:6, and air-coated onto the outside of the core layer. The modified bio-based poly(propylene terephthalate) fiber is prepared by online blending modification with a maleic anhydride-grafted polyester compatibilizer. Using bio-based poly(propylene terephthalate) fiber (DuPont (CovationBio) Sorona® bio-based PTT fiber) as the matrix, 3% by weight of maleic anhydride-grafted PTT compatibilizer (MAH-g-PTT compatibilizer, ST-1 type MAH grafted polyester compatibilizer from Nanjing Sutai Polymer Technology Co., Ltd.) is added. After online blending, carding, and spinning, modified bio-based poly(propylene terephthalate) fiber is obtained. The recycled polyester fiber has a linear density of 1.2 dtex and a length of 38 mm. The middle layer has a linear density of 17.5 dtex, a wrapping twist of 370 twists / meter, and a wrapping rate of 96%. Outer layer: Hemp fiber was modified at 55°C for 40 minutes using a 7% (w / w) sodium hydroxide solution to obtain modified hemp fiber; the modified hemp fiber had a linear density of 1.5 dtex and a length of 40 mm; the modified hemp fiber was blended with lyocell fiber at a mass ratio of 3:7, with the addition of 1.0 wt% pearlescent pigment and 0.5 wt% antistatic agent, and then melt-spun to coat the outer side of the middle layer. The melt-spun process parameters were: melt temperature 270°C, spinning box temperature... The temperature was 270℃, component pressure was 14MPa, cooling air temperature was 20℃, wind speed was 0.5m / s, draw ratio was 1.4 times, heat setting temperature was 120℃, and winding speed was 320m / min; the outer layer linear density was 24.5dtex, and the covering twist was 420 twists / meter. The pearlescent pigment had a particle size of 2μm and was a textile-grade mica-based pearlescent pigment composed of mica titanium oxide; the lyocell fiber had a linear density of 1.3dtex and a length of 39mm. Post-treatment: Green crosslinking finishing uses an environmentally friendly waterborne polyurethane crosslinking agent (Covestro Imprafix® IO3388 waterborne blocked aliphatic polyisocyanate crosslinking agent), with an addition amount of 2.5 wt% of the composite yarn mass. The padding method (liquor ratio 1:20) is used, and the crosslinking is carried out at 90℃ for 40 min. After crosslinking, the yarn is dried with cold air (temperature 25℃) until the moisture content is ≤8%. Natural plant oil setting uses an epoxidized soybean oil-based textile-specific natural plant oil agent (Shanghai Gerunning GR-260DB), with an addition amount of 3.0 wt% of the composite yarn mass. After being evenly sprayed onto the surface of the composite yarn, it is set at 120℃ for 30 min. During the setting process, the yarn tension is controlled at 5 cN. After setting, the yarn is naturally cooled to room temperature. Example 2

[0032] Example 2 provides an eco-friendly, comfortable, multi-functional elastic composite yarn with a three-layer structure consisting of a core layer, a middle layer, and an outer layer from the inside out: Core layer: made of low viscosity PET (viscosity 0.47dL / g) and high shrinkage PET (boiling water shrinkage rate 20%) blended in a mass ratio of 5:5 by vortex spinning, with a linear density of 8.5dtex and a spinning speed of 390m / min; Middle layer: Modified bio-based poly(propylene terephthalate) fiber and recycled polyester fiber are blended at a mass ratio of 3:7, and air-coated on the outside of the core layer. The modified bio-based poly(propylene terephthalate) fiber is prepared by online blending modification with a maleic anhydride-grafted polyester compatibilizer. Using bio-based poly(propylene terephthalate) fiber (DuPont (CovationBio) Sorona® bio-based PTT fiber) as the matrix, 3% by weight of maleic anhydride-grafted PTT compatibilizer (MAH-g-PTT compatibilizer, ST-1 type MAH grafted polyester compatibilizer from Nanjing Sutai Polymer Technology Co., Ltd.) is added. After online blending, carding, and spinning, modified bio-based poly(propylene terephthalate) fiber is obtained. The recycled polyester fiber has a linear density of 1.2 dtex and a length of 38 mm. The middle layer has a linear density of 15.5 dtex, a wrapping twist of 370 twists / meter, and a wrapping rate of 96%. Outer layer: Hemp fiber was modified at 65°C for 35 minutes using a 7% (w / w) sodium hydroxide solution to obtain modified hemp fiber; the modified hemp fiber had a linear density of 1.5 dtex and a length of 40 mm; the modified hemp fiber was blended with lyocell fiber at a mass ratio of 2:8, with the addition of 0.8 wt% pearlescent pigment and 0.3 wt% antistatic agent, and then melt-spun to coat the outer side of the middle layer. The melt-spun process parameters were: melt temperature 270°C, spinning box temperature... The temperature was 270℃, component pressure was 14MPa, cooling air temperature was 20℃, wind speed was 0.5m / s, draw ratio was 1.4 times, heat setting temperature was 120℃, and winding speed was 320m / min; the outer layer linear density was 22.5dtex, the covering twist was 420 twists / meter, wherein the pearlescent pigment had a particle size of 2μm, the pearlescent pigment was a textile grade mica-based pearlescent pigment, and the composition was mica titanium oxide; the lyocell fiber had a linear density of 1.3dtex and a length of 39mm; Post-treatment: Green crosslinking finishing uses an environmentally friendly waterborne polyurethane crosslinking agent (Covestro Imprafix® IO3388 waterborne blocked aliphatic polyisocyanate crosslinking agent), with an addition amount of 2.0 wt% of the composite yarn mass. The padding method (liquor ratio 1:20) is used, and the crosslinking is carried out at 100℃ for 30 min. After crosslinking, the yarn is dried with cold air (temperature 25℃) until the moisture content is ≤8%. Natural plant oil setting uses an epoxidized soybean oil-based textile-specific natural plant oil agent (Shanghai Gerunning GR-260DB), with an addition amount of 2.5 wt% of the composite yarn mass. After being evenly sprayed onto the surface of the composite yarn, it is set at 110℃ for 20 min. During the setting process, the yarn tension is controlled at 4 cN. After setting, the yarn is naturally cooled to room temperature. Example 3

[0033] Example 3 provides an eco-friendly, comfortable, multi-functional elastic composite yarn with a three-layer structure consisting of a core layer, a middle layer, and an outer layer from the inside out: Core layer: made of low viscosity PET (viscosity 0.65dL / g) and high shrinkage PET (boiling water shrinkage rate 25%) blended in a mass ratio of 7:3 by vortex spinning, with a linear density of 12.5dtex and a spinning speed of 410m / min; Middle layer: Modified bio-based poly(propylene terephthalate) fiber and recycled polyester fiber are blended at a mass ratio of 5:5 and air-coated on the outside of the core layer. The modified bio-based poly(propylene terephthalate) fiber is prepared by online blending modification with a maleic anhydride-grafted polyester compatibilizer. Using bio-based poly(propylene terephthalate) fiber (DuPont (CovationBio) Sorona® bio-based PTT fiber) as the matrix, 3% by weight of maleic anhydride-grafted PTT compatibilizer (MAH-g-PTT compatibilizer, ST-1 type MAH grafted polyester compatibilizer from Nanjing Sutai Polymer Technology Co., Ltd.) is added. After online blending, carding, and spinning, modified bio-based poly(propylene terephthalate) fiber is obtained. The recycled polyester fiber has a linear density of 1.2 dtex and a length of 38 mm. The middle layer has a linear density of 19.5 dtex, a wrapping twist of 370 twists / meter, and a wrapping rate of 96%. Outer layer: Hemp fiber was modified at 75°C for 30 minutes using a 7% (w / w) sodium hydroxide solution to obtain modified hemp fiber; the modified hemp fiber had a linear density of 1.5 dtex and a length of 40 mm; the modified hemp fiber was blended with lyocell fiber at a mass ratio of 4:6, with the addition of 1.2 wt% pearlescent pigment and 0.7 wt% antistatic agent, and then melt-spun to coat the outer side of the middle layer. The melt-spun process parameters were: melt temperature 270°C, spinning box temperature... The temperature was 270℃, component pressure was 14MPa, cooling air temperature was 20℃, wind speed was 0.5m / s, draw ratio was 1.4 times, heat setting temperature was 120℃, and winding speed was 320m / min; the outer layer linear density was 26.5dtex, the covering twist was 420 twists / meter, wherein the pearlescent pigment had a particle size of 2μm, the pearlescent pigment was a textile grade mica-based pearlescent pigment, and the composition was mica titanium oxide; the lyocell fiber had a linear density of 1.3dtex and a length of 39mm; Post-treatment: Green crosslinking finishing uses an environmentally friendly waterborne polyurethane crosslinking agent (Covestro Imprafix® IO3388 waterborne blocked aliphatic polyisocyanate crosslinking agent), with an addition amount of 3.0 wt% of the composite yarn mass. The padding method (liquor ratio 1:20) is used, and the crosslinking is carried out at 80℃ for 50 min. After crosslinking, the yarn is dried with cold air (temperature 25℃) until the moisture content is ≤8%. Natural plant oil setting uses an epoxidized soybean oil-based textile-specific natural plant oil agent (Shanghai Gerunning GR-260DB), with an addition amount of 3.5 wt% of the composite yarn mass. After being evenly sprayed onto the surface of the composite yarn, it is set at a constant temperature of 130℃ for 40 min. During the setting process, the yarn tension is controlled at 6 cN. After setting, the yarn is naturally cooled to room temperature.

[0034] Comparative Example 1 Comparative Example 1 provides an eco-friendly, comfortable, multi-functional elastic composite yarn with a three-layer structure consisting of a core layer and an outer layer from the inside out: Core layer: made of low viscosity PET (viscosity 0.55dL / g) and high shrinkage PET (boiling water shrinkage rate 22%) blended in a mass ratio of 6:4 by vortex spinning, with a linear density of 10.5dtex and a spinning speed of 400m / min; Outer layer: Hemp fiber was modified at 55°C for 40 minutes using a 7% (w / w) sodium hydroxide solution to obtain modified hemp fiber; the modified hemp fiber had a linear density of 1.5 dtex and a length of 40 mm; the modified hemp fiber was blended with lyocell fiber at a mass ratio of 3:7, with the addition of 1.0 wt% pearlescent pigment and 0.5 wt% antistatic agent, and then melt-spun to coat the outer side of the middle layer. The melt-spun process parameters were: melt temperature 270°C, spinning box temperature... The temperature was 270℃, component pressure was 14MPa, cooling air temperature was 20℃, wind speed was 0.5m / s, draw ratio was 1.4 times, heat setting temperature was 120℃, and winding speed was 320m / min; the outer layer linear density was 24.5dtex, and the covering twist was 420 twists / meter. The pearlescent pigment had a particle size of 2μm and was a textile-grade mica-based pearlescent pigment composed of mica titanium oxide; the lyocell fiber had a linear density of 1.3dtex and a length of 39mm. Post-treatment: Green crosslinking finishing uses an environmentally friendly waterborne polyurethane crosslinking agent (Covestro Imprafix® IO3388 waterborne blocked aliphatic polyisocyanate crosslinking agent), with an addition amount of 2.5 wt% of the composite yarn mass. The padding method (liquor ratio 1:20) is used, and the crosslinking is carried out at 90℃ for 40 min. After crosslinking, the yarn is dried with cold air (temperature 25℃) until the moisture content is ≤8%. Natural plant oil setting uses an epoxidized soybean oil-based textile-specific natural plant oil agent (Shanghai Gerunning GR-260DB), with an addition amount of 3.0 wt% of the composite yarn mass. After being evenly sprayed onto the surface of the composite yarn, it is set at 120℃ for 30 min. During the setting process, the yarn tension is controlled at 5 cN. After setting, the yarn is naturally cooled to room temperature.

[0035] Comparative Example 2 The composite yarn provided in Comparative Example 2 has a three-layer structure, consisting of a core layer and a middle layer from the inside out: Core layer: made of low viscosity PET (viscosity 0.55dL / g) and high shrinkage PET (boiling water shrinkage rate 22%) blended in a mass ratio of 6:4 by vortex spinning, with a linear density of 10.5dtex and a spinning speed of 400m / min; Middle layer: Modified bio-based poly(propylene terephthalate) fiber and recycled polyester fiber are blended at a mass ratio of 4:6, and air-coated on the outside of the core layer. The modified bio-based poly(propylene terephthalate) fiber is prepared by online blending modification with maleic anhydride-grafted polyester compatibilizer: using a bio-based poly(propylene terephthalate) fiber matrix (DuPont (CovationBio) Sorona® bio-based PTT fiber) as the matrix, 3% maleic acid is added by weight of the fiber. Modified bio-based polypropylene terephthalate (PPT) fibers were prepared by online blending, carding, spinning, or air-jet coating of anhydride-grafted PTT compatibilizer (MAH-g-PTT compatibilizer, ST-1 type MAH grafted polyester compatibilizer from Nanjing Sutai Polymer Technology Co., Ltd.). The recycled polyester fibers had a linear density of 1.2 dtex and a length of 38 mm; the middle layer had a linear density of 17.5 dtex, a coating twist of 370 twists / meter, and a coating rate of 96%. Post-treatment: Green crosslinking finishing uses an environmentally friendly waterborne polyurethane crosslinking agent (Covestro Imprafix® IO3388 waterborne blocked aliphatic polyisocyanate crosslinking agent), with an addition amount of 2.5 wt% of the composite yarn mass. The padding method (liquor ratio 1:20) is used, and the crosslinking is carried out at 90℃ for 40 min. After crosslinking, the yarn is dried with cold air (temperature 25℃) until the moisture content is ≤8%. Natural plant oil setting uses an epoxidized soybean oil-based textile-specific natural plant oil agent (Shanghai Gerunning GR-260DB), with an addition amount of 3.0 wt% of the composite yarn mass. After being evenly sprayed onto the surface of the composite yarn, it is set at 120℃ for 30 min. During the setting process, the yarn tension is controlled at 5 cN. After setting, the yarn is naturally cooled to room temperature.

[0036] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the core layer uses a single low-viscosity PET and does not contain high-shrinkage PET, while the other parameters are the same as those in Example 1.

[0037] Comparative Example 4 Comparative Example 4 provides a bio-based elastic composite yarn as a control group for performance comparison with the embodiments of the present invention. Raw material preparation Bio-based polyester fiber: conventional textile-grade bio-based PET fiber, linear density 1.4 dtex, length 38 mm; Spandex filament: conventional textile-grade spandex, linear density 11.0 dtex; Conventional polyester fiber: textile-grade virgin polyester fiber, linear density 1.2 dtex, length 38 mm; Conventional dyeing agents and finishing agents: traditional non-environmentally friendly auxiliaries in the textile industry. This bio-based elastic composite yarn has a double-layer structure, consisting of an spandex core layer and a bio-based polyester coating layer from the inside out. The specific preparation steps are as follows: S1 raw material pretreatment: Bio-based polyester fiber and conventional polyester fiber are opened and combed to remove impurities; spandex filament is pre-stretched to a stretch ratio of 1.5 times. S2 Core Layer Preparation: Conventional spandex yarn is used as the core layer, with a linear density controlled at 11.0 dtex. No special spinning process is required; the raw yarn is used directly as the core layer. S3 coating process: Bio-based polyester fiber and conventional polyester fiber are blended at a mass ratio of 6:4 and coated on the outside of the spandex core layer using conventional ring spinning coating process. The coating twist is 360 twists / meter, the coating rate is 92%, and the linear density of the coated yarn is controlled at 42.0 dtex. S4 finishing: The dyeing process is carried out using the traditional high temperature and high pressure dyeing process. The dyeing temperature is 130℃ and the dyeing time is 60min. After dyeing, the conventional finishing agent is used for setting. The conventional finishing agent is hydroxymethyl melamine resin finishing agent (Shandong Zibo Da Ranfang DRF-800). The setting temperature is 140℃ and the setting time is 30min. S5 Inspection, Winding, and Packaging: The finished composite yarn is subjected to performance testing according to the same standards as in the embodiments of this invention. After passing the test, it is wound and packaged to obtain the finished product.

[0038] Performance testing standards and experimental methods The performance testing standards and experimental methods for all embodiments 1-3 and comparative examples 1-4 of this invention are as follows: The linear density (dtex) test follows GB / T 14343-2008 "Test Method for Linear Density of Chemical Fibers". A linear density tester is used for sampling and measurement, and the average value is taken through multiple tests to ensure data accuracy. The breaking strength (cN / dtex) test follows GB / T 14344-2015 "Test Method for Tensile Properties of Chemical Fibers Short Fibers". A fiber tensile testing machine is used, a standard tensile speed is set, the maximum load at which the yarn breaks is tested and the breaking strength is calculated. The elastic recovery rate of the yarn should be tested according to GB / T14344-2015 "Test Method for Tensile Properties of Chemical Fibers Short Fibers". The fiber tensile testing machine should be used, with the tensile speed set at 20 mm / min and the tensile ratio at 10%, and 50 tensile-rebound cycles should be performed. The antibacterial rate (%) test follows GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Shaking method". The yarn sample is in contact with standard strains (Escherichia coli and Staphylococcus aureus) using the shaking method, and the antibacterial rate is calculated. The UV protection UPF test follows GB / T 18830-2009 "Evaluation of UV protection performance of textiles". The transmittance of yarn to UVA and UVB is tested using a UV spectrophotometer, and the UPF value is calculated. Formaldehyde residue (mg / kg) was tested in accordance with GB / T 2912.1-2009 "Textiles - Determination of formaldehyde - Part 1: Free and hydrolyzed formaldehyde (water extraction method)". Formaldehyde in the yarn was extracted by water extraction method, and the formaldehyde concentration was determined by spectrophotometry and the residue was calculated. COD emission reduction rate (%): refers to the percentage reduction in total COD emissions from the entire production process of this invention (S1 raw material pretreatment to S5 finishing) compared to the traditional elastic composite yarn production process in the textile industry (ring spinning + high temperature and high pressure dyeing + oil-based crosslinking finishing) when producing the same mass (1kg) of composite yarn. Testing points: Wastewater samples were taken from the discharge outlets of the four core processes of raw material cleaning, spinning, coating and finishing in both processes. The sample volume for each process was 500 mL. The testing followed GB / T 11914-1989 "Determination of Chemical Oxygen Demand in Water - Dichromate Method". Calculation method: Total COD emissions = COD emission concentration of each process (mg / L) × wastewater discharge of each process (L / kg); COD emission reduction rate = [(Total COD emissions from traditional processes - Total COD emissions from the process of this invention) / Total COD emissions from traditional processes] × 100%; all processes were measured in parallel three times, and the average value was taken. The structural stability (%) test followed FZ / T01058-2012 "Determination of abrasion resistance of yarns in textiles - Martindale method", using a Martindale abrasion tester. The test parameters were: test load 9 kPa, abrasive material standard cotton canvas, and 500 abrasion cycles. The retention rate of the breaking strength of the yarn after abrasion was used as the evaluation index. The structural stability rate = (breaking strength after abrasion / breaking strength before abrasion) × 100%. The number of test samples was ≥10, and the average value was taken.

[0039] The experimental data of the performance tests of Examples 1-3 and Comparative Examples 1-4, which were conducted using the above-mentioned performance testing standards and experimental methods, are shown in Table 1 below: Table 1. Experimental data for performance tests of Examples 1-3 and Comparative Examples 1-4. Table Notes: 1. Structural stability: The test follows FZ / T 01058-2012, which is the retention rate of breaking strength of the yarn after being subjected to a 9kPa load and 500 cycles of friction using the Martindale method; 2. COD emission reduction rate: The total COD emission of the entire production process (raw material pretreatment to finishing) for producing 1 kg of composite yarn is compared. The test follows GB / T11914-1989, and the benchmark is the traditional elastic composite yarn production process in the textile industry (ring spinning + high temperature and high pressure dyeing + oil crosslinking finishing). 3. For the testing standards and methods of other testing items, please refer to the "Performance Testing Standards and Experimental Methods" section of this manual.

[0040] From Table 1, we can observe that the performance of Examples 1-3 meets the indicators defined by the present invention and is superior to Comparative Example 4 (the prior art), indicating that the technical solution of the present invention can effectively achieve synergistic improvement in replacing spandex, being eco-friendly, and integrating multiple functions, and has significant technical advantages. The breaking strength, elastic recovery rate, and structural stability of Comparative Example 1 (without the middle layer) all decreased significantly, indicating that the middle layer can effectively improve the structural stability and mechanical properties of the composite yarn. Comparative Example 2 (without outer layer) showed a significant decrease in antibacterial rate and UV protection UPF, and lacked a pearlescent texture, indicating that the outer layer is key to achieving multifunctionality and eco-friendly texture. The elastic recovery rate and attenuation of Comparative Example 3 (single core layer material) deteriorated significantly, indicating that the ratio design of the two-component core layer is the core to achieving the replacement of spandex. The antibacterial rate in Comparative Example 1 (90.2%) was slightly lower than that in Example 1 (90.8%). This is mainly because the removal of the middle layer reduced the physical bonding between the core and outer layers, resulting in a slight decrease in the contact area between the antibacterial active ingredients of the modified hemp fiber and the bacterial strain. This led to a slight decrease in the antibacterial rate compared to the Example 1, but the value still meets the core indicator of ≥90% specified in this invention. By specifying a middle layer coverage rate of ≥95% in the claims, this invention effectively improves the bonding tightness between the core and outer layers, prevents the loss of contact area for the antibacterial active ingredients, and further ensures the stability of the antibacterial performance. This fully demonstrates the supporting role of the middle layer structure in the overall performance of the composite yarn. The formaldehyde residue in all embodiments was ≤0.02mg / kg, and the COD emission reduction rate was ≥80%, which is significantly better than the prior art, indicating that the green production process of the present invention has significant environmental advantages.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An eco-friendly, comfortable, multi-functional elastic composite yarn, characterized in that, include: The core layer is an elastic core yarn formed by blending low-viscosity PET and high-shrinkage PET in a mass ratio of (5-7):(3-5), wherein the intrinsic viscosity of the low-viscosity PET at 25°C is 0.47-0.65 dL / g, and the boiling water shrinkage rate of the high-shrinkage PET is ≥20%. The middle layer covers the outside of the core layer and is formed by blending modified bio-based poly(propylene terephthalate) fiber and recycled polyester fiber in a mass ratio of (3-5):(5-7). The outer layer covers the outside of the middle layer and is formed by blending modified hemp fiber and lyocell fiber in a mass ratio of (2-4):(6-8).

2. The eco-friendly, comfortable, multi-functional elastic composite yarn according to claim 1, characterized in that, The modified bio-based polypropylene terephthalate fiber is modified by maleic anhydride grafting.

3. The eco-friendly, comfortable, multi-functional elastic composite yarn according to claim 1, characterized in that, The outer layer contains 0.8-1.2 wt% pearlescent pigment and 0.3-0.7 wt% antistatic agent, wherein the pearlescent pigment has a particle size of 1-3 μm.

4. The eco-friendly, comfortable, multi-functional elastic composite yarn according to claim 1, characterized in that, The linear density of the core layer is 8.5~12.5 dtex; The linear density of the middle layer is 15.5~19.5 dtex, its coverage rate is ≥95%, and its coverage twist is 350~390 twists / meter; The linear density of the outer layer is 22.5~26.5 dtex, and its wrapping twist is 400~440 twists / meter.

5. The eco-friendly, comfortable, multi-functional elastic composite yarn according to claim 1, characterized in that, The composite yarn has a bus density of 46.5~58.5 dtex.

6. A method for manufacturing an eco-friendly, comfortable, multi-functional elastic composite yarn, comprising the following steps: S1 Raw Material Pretreatment: Low-viscosity PET, high-shrinkage PET, modified bio-based poly(propylene terephthalate) fiber, recycled polyester fiber, modified hemp fiber, and lyocell fiber are opened and combed respectively. S2 core layer preparation: Low viscosity PET and high shrinkage PET are spun using vortex spinning process at a spinning speed of 380~420m / min; S3 middle layer coating: Modified bio-based polypropylene terephthalate fiber is blended with recycled polyester fiber and then coated on the outside of the core layer using an airflow coating process. S4 outer layer coating: Modified hemp fiber and lyocell fiber are blended, pearlescent pigments and antistatic agents are added, and after being mixed evenly, they are melt-spun and coated on the outer side of the middle layer.

7. The method for manufacturing the eco-friendly, comfortable, multifunctional elastic composite yarn according to claim 6, characterized in that, The modified hemp fiber is modified by alkali treatment, with the modifier being a 5%~9% mass percentage sodium hydroxide solution, the modification temperature being 55~75℃, and the modification time being 30~40min.

8. The method for manufacturing the eco-friendly, comfortable, multifunctional elastic composite yarn according to claim 6, characterized in that, It also includes the following steps: S5 finishing: The coated composite yarn is subjected to green cross-linking finishing and natural plant oil setting. The finishing temperature is 80~100℃, the finishing time is 30~50min, the setting temperature is 110~130℃, and the setting time is 20~40min. S6 inspection, winding, and packaging.

9. The method for manufacturing the eco-friendly, comfortable, multifunctional elastic composite yarn according to claim 8, characterized in that, The green crosslinking finish uses an environmentally friendly water-based polyurethane crosslinking agent, which is added at a rate of 2.0 to 3.0 wt% of the composite yarn mass.

10. The method for manufacturing the eco-friendly, comfortable, multifunctional elastic composite yarn according to claim 8, characterized in that, The natural plant oil agent used for shaping is a soybean-based natural plant oil agent, and its addition amount is 2.5~3.5wt% of the weight of the composite yarn.

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